| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Alexei Starovoitov | 21531 | 20.33% | 167 | 14.21% |
| Andrii Nakryiko | 14261 | 13.46% | 114 | 9.70% |
| Kumar Kartikeya Dwivedi | 11062 | 10.44% | 77 | 6.55% |
| Yonghong Song | 7327 | 6.92% | 75 | 6.38% |
| Eduard Zingerman | 6322 | 5.97% | 41 | 3.49% |
| John Fastabend | 6219 | 5.87% | 17 | 1.45% |
| Daniel Borkmann | 5652 | 5.34% | 131 | 11.15% |
| Martin KaFai Lau | 5479 | 5.17% | 49 | 4.17% |
| Dave Marchevsky | 2975 | 2.81% | 28 | 2.38% |
| Jakub Kiciński | 2663 | 2.51% | 34 | 2.89% |
| Joanne Koong | 2523 | 2.38% | 21 | 1.79% |
| Edward Cree | 2331 | 2.20% | 9 | 0.77% |
| Lorenz Bauer | 1217 | 1.15% | 19 | 1.62% |
| Andrei Matei | 1208 | 1.14% | 9 | 0.77% |
| Jiong Wang | 1083 | 1.02% | 16 | 1.36% |
| Jiri Olsa | 1064 | 1.00% | 13 | 1.11% |
| Hao Luo | 972 | 0.92% | 12 | 1.02% |
| Benjamin Tissoires | 836 | 0.79% | 11 | 0.94% |
| Joe Stringer | 637 | 0.60% | 7 | 0.60% |
| David Vernet | 596 | 0.56% | 15 | 1.28% |
| Andrey Ignatov | 580 | 0.55% | 11 | 0.94% |
| Toke Höiland-Jörgensen | 565 | 0.53% | 12 | 1.02% |
| Song Liu | 499 | 0.47% | 5 | 0.43% |
| Ilya Leoshkevich | 474 | 0.45% | 10 | 0.85% |
| Maciej Fijalkowski | 345 | 0.33% | 4 | 0.34% |
| Maxim Mikityanskiy | 326 | 0.31% | 9 | 0.77% |
| Shung-Hsi Yu | 302 | 0.29% | 6 | 0.51% |
| Kui-Feng Lee | 294 | 0.28% | 11 | 0.94% |
| David S. Miller | 294 | 0.28% | 9 | 0.77% |
| Xu Kuohai | 286 | 0.27% | 3 | 0.26% |
| Puranjay Mohan | 283 | 0.27% | 5 | 0.43% |
| Chuyi Zhou | 275 | 0.26% | 4 | 0.34% |
| Wedson Almeida Filho | 244 | 0.23% | 1 | 0.09% |
| Dmitrii Banshchikov | 241 | 0.23% | 5 | 0.43% |
| Stanislav Fomichev | 234 | 0.22% | 7 | 0.60% |
| Florent Revest | 220 | 0.21% | 5 | 0.43% |
| Josef Bacik | 194 | 0.18% | 3 | 0.26% |
| KP Singh | 185 | 0.17% | 12 | 1.02% |
| Menglong Dong | 176 | 0.17% | 1 | 0.09% |
| Hou Tao | 172 | 0.16% | 5 | 0.43% |
| Brendan Jackman | 167 | 0.16% | 7 | 0.60% |
| Philo Lu | 163 | 0.15% | 3 | 0.26% |
| Christy Lee | 148 | 0.14% | 3 | 0.26% |
| Matt Mullins | 145 | 0.14% | 1 | 0.09% |
| Gianluca Borello | 144 | 0.14% | 5 | 0.43% |
| Harishankar Vishwanathan | 140 | 0.13% | 2 | 0.17% |
| Petar Penkov | 128 | 0.12% | 1 | 0.09% |
| Juntong Deng | 118 | 0.11% | 1 | 0.09% |
| Yafang Shao | 117 | 0.11% | 5 | 0.43% |
| Jann Horn | 115 | 0.11% | 5 | 0.43% |
| Cupertino Miranda | 109 | 0.10% | 2 | 0.17% |
| Roman Gushchin | 103 | 0.10% | 7 | 0.60% |
| Jakub Sitnicki | 100 | 0.09% | 4 | 0.34% |
| Thomas Graf | 100 | 0.09% | 3 | 0.26% |
| Kees Cook | 90 | 0.08% | 6 | 0.51% |
| Daniel Rosenberg | 85 | 0.08% | 2 | 0.17% |
| Feng Zhou | 84 | 0.08% | 1 | 0.09% |
| Viktor Malik | 83 | 0.08% | 2 | 0.17% |
| Quentin Monnet | 80 | 0.08% | 4 | 0.34% |
| Hao Sun | 80 | 0.08% | 4 | 0.34% |
| Björn Töpel | 72 | 0.07% | 3 | 0.26% |
| Anton Protopopov | 67 | 0.06% | 2 | 0.17% |
| Lawrence Brakmo | 66 | 0.06% | 2 | 0.17% |
| Mauricio Vasquez B | 65 | 0.06% | 2 | 0.17% |
| He Fengqing | 62 | 0.06% | 1 | 0.09% |
| Matt Bobrowski | 59 | 0.06% | 2 | 0.17% |
| Brenden Blanco | 56 | 0.05% | 2 | 0.17% |
| Jonathan Lemon | 52 | 0.05% | 1 | 0.09% |
| Xia Kaixu | 50 | 0.05% | 2 | 0.17% |
| Roberto Sassu | 47 | 0.04% | 2 | 0.17% |
| Alan Maguire | 41 | 0.04% | 1 | 0.09% |
| Udip Pant | 40 | 0.04% | 1 | 0.09% |
| Piotr Krysiuk | 39 | 0.04% | 2 | 0.17% |
| Artem Savkov | 39 | 0.04% | 1 | 0.09% |
| Dmitrii Dolgov | 37 | 0.03% | 1 | 0.09% |
| Krister Johansen | 32 | 0.03% | 1 | 0.09% |
| Jesper Dangaard Brouer | 29 | 0.03% | 4 | 0.34% |
| Vadim Fedorenko | 29 | 0.03% | 2 | 0.17% |
| Namhyung Kim | 28 | 0.03% | 1 | 0.09% |
| Yinjun Zhang | 28 | 0.03% | 1 | 0.09% |
| Daniel Xu | 27 | 0.03% | 2 | 0.17% |
| Leon Huayra | 27 | 0.03% | 2 | 0.17% |
| Sandipan Das | 26 | 0.02% | 2 | 0.17% |
| Rabin Vincent | 25 | 0.02% | 1 | 0.09% |
| Andrea Righi | 25 | 0.02% | 1 | 0.09% |
| Paul Chaignon | 25 | 0.02% | 3 | 0.26% |
| Johannes Berg | 24 | 0.02% | 2 | 0.17% |
| Daan De Meyer | 24 | 0.02% | 1 | 0.09% |
| Tao Lyu | 24 | 0.02% | 2 | 0.17% |
| Arnd Bergmann | 19 | 0.02% | 2 | 0.17% |
| Craig Gallek | 18 | 0.02% | 1 | 0.09% |
| Christophe Leroy | 17 | 0.02% | 1 | 0.09% |
| Bixuan Cui | 16 | 0.02% | 1 | 0.09% |
| Wang Yufen | 14 | 0.01% | 1 | 0.09% |
| Luis Gerhorst | 14 | 0.01% | 2 | 0.17% |
| Arthur Fabre | 14 | 0.01% | 1 | 0.09% |
| Florian Westphal | 12 | 0.01% | 1 | 0.09% |
| Maciej Żenczykowski | 11 | 0.01% | 1 | 0.09% |
| Randy Dunlap | 11 | 0.01% | 2 | 0.17% |
| Matthieu Baerts | 9 | 0.01% | 1 | 0.09% |
| Gustavo A. R. Silva | 8 | 0.01% | 3 | 0.26% |
| Rafael Passos | 8 | 0.01% | 2 | 0.17% |
| Dimitar Kanaliev | 8 | 0.01% | 1 | 0.09% |
| JP Kobryn | 7 | 0.01% | 1 | 0.09% |
| Daniel T. Lee | 7 | 0.01% | 1 | 0.09% |
| Eelco Chaudron | 7 | 0.01% | 1 | 0.09% |
| Sargun Dhillon | 7 | 0.01% | 1 | 0.09% |
| Nikolay Aleksandrov | 6 | 0.01% | 1 | 0.09% |
| Eric Dumazet | 6 | 0.01% | 2 | 0.17% |
| Chenbo Feng | 6 | 0.01% | 1 | 0.09% |
| Aditi Ghag | 6 | 0.01% | 1 | 0.09% |
| Brian Vazquez | 6 | 0.01% | 2 | 0.17% |
| Hari Bathini | 5 | 0.00% | 1 | 0.09% |
| Al Viro | 5 | 0.00% | 1 | 0.09% |
| Peter Oskolkov | 5 | 0.00% | 1 | 0.09% |
| Alexey Dobriyan | 5 | 0.00% | 1 | 0.09% |
| Zhen Lei | 4 | 0.00% | 1 | 0.09% |
| Ingo Molnar | 4 | 0.00% | 1 | 0.09% |
| Vlastimil Babka | 4 | 0.00% | 2 | 0.17% |
| Geliang Tang | 4 | 0.00% | 1 | 0.09% |
| Sean Young | 4 | 0.00% | 1 | 0.09% |
| Akinobu Mita | 3 | 0.00% | 1 | 0.09% |
| Kefeng Wang | 3 | 0.00% | 1 | 0.09% |
| Mathieu Xhonneux | 3 | 0.00% | 1 | 0.09% |
| Christoph Hellwig | 3 | 0.00% | 1 | 0.09% |
| Gilad Reti | 3 | 0.00% | 1 | 0.09% |
| Colin Ian King | 2 | 0.00% | 2 | 0.17% |
| Rik Van Riel | 2 | 0.00% | 1 | 0.09% |
| Tony Ambardar | 2 | 0.00% | 1 | 0.09% |
| Thomas Gleixner | 2 | 0.00% | 1 | 0.09% |
| Dan Carpenter | 2 | 0.00% | 1 | 0.09% |
| Tobias Klauser | 2 | 0.00% | 1 | 0.09% |
| Krzesimir Nowak | 1 | 0.00% | 1 | 0.09% |
| Yuntao Wang | 1 | 0.00% | 1 | 0.09% |
| Matteo Croce | 1 | 0.00% | 1 | 0.09% |
| Jason A. Donenfeld | 1 | 0.00% | 1 | 0.09% |
| Alex Gartrell | 1 | 0.00% | 1 | 0.09% |
| Mykyta Yatsenko | 1 | 0.00% | 1 | 0.09% |
| Simon Horman | 1 | 0.00% | 1 | 0.09% |
| Will Deacon | 1 | 0.00% | 1 | 0.09% |
| Matthew Wilcox | 1 | 0.00% | 1 | 0.09% |
| Simon Wang | 1 | 0.00% | 1 | 0.09% |
| Prashant Bhole | 1 | 0.00% | 1 | 0.09% |
| Total | 105926 | 1175 |
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// SPDX-License-Identifier: GPL-2.0-only /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com * Copyright (c) 2016 Facebook * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io */ #include <uapi/linux/btf.h> #include <linux/bpf-cgroup.h> #include <linux/kernel.h> #include <linux/types.h> #include <linux/slab.h> #include <linux/bpf.h> #include <linux/btf.h> #include <linux/bpf_verifier.h> #include <linux/filter.h> #include <net/netlink.h> #include <linux/file.h> #include <linux/vmalloc.h> #include <linux/stringify.h> #include <linux/bsearch.h> #include <linux/sort.h> #include <linux/perf_event.h> #include <linux/ctype.h> #include <linux/error-injection.h> #include <linux/bpf_lsm.h> #include <linux/btf_ids.h> #include <linux/poison.h> #include <linux/module.h> #include <linux/cpumask.h> #include <linux/bpf_mem_alloc.h> #include <net/xdp.h> #include <linux/trace_events.h> #include <linux/kallsyms.h> #include "disasm.h" static const struct bpf_verifier_ops * const bpf_verifier_ops[] = { #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \ [_id] = & _name ## _verifier_ops, #define BPF_MAP_TYPE(_id, _ops) #define BPF_LINK_TYPE(_id, _name) #include <linux/bpf_types.h> #undef BPF_PROG_TYPE #undef BPF_MAP_TYPE #undef BPF_LINK_TYPE }; struct bpf_mem_alloc bpf_global_percpu_ma; static bool bpf_global_percpu_ma_set; /* bpf_check() is a static code analyzer that walks eBPF program * instruction by instruction and updates register/stack state. * All paths of conditional branches are analyzed until 'bpf_exit' insn. * * The first pass is depth-first-search to check that the program is a DAG. * It rejects the following programs: * - larger than BPF_MAXINSNS insns * - if loop is present (detected via back-edge) * - unreachable insns exist (shouldn't be a forest. program = one function) * - out of bounds or malformed jumps * The second pass is all possible path descent from the 1st insn. * Since it's analyzing all paths through the program, the length of the * analysis is limited to 64k insn, which may be hit even if total number of * insn is less then 4K, but there are too many branches that change stack/regs. * Number of 'branches to be analyzed' is limited to 1k * * On entry to each instruction, each register has a type, and the instruction * changes the types of the registers depending on instruction semantics. * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is * copied to R1. * * All registers are 64-bit. * R0 - return register * R1-R5 argument passing registers * R6-R9 callee saved registers * R10 - frame pointer read-only * * At the start of BPF program the register R1 contains a pointer to bpf_context * and has type PTR_TO_CTX. * * Verifier tracks arithmetic operations on pointers in case: * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), * 1st insn copies R10 (which has FRAME_PTR) type into R1 * and 2nd arithmetic instruction is pattern matched to recognize * that it wants to construct a pointer to some element within stack. * So after 2nd insn, the register R1 has type PTR_TO_STACK * (and -20 constant is saved for further stack bounds checking). * Meaning that this reg is a pointer to stack plus known immediate constant. * * Most of the time the registers have SCALAR_VALUE type, which * means the register has some value, but it's not a valid pointer. * (like pointer plus pointer becomes SCALAR_VALUE type) * * When verifier sees load or store instructions the type of base register * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are * four pointer types recognized by check_mem_access() function. * * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' * and the range of [ptr, ptr + map's value_size) is accessible. * * registers used to pass values to function calls are checked against * function argument constraints. * * ARG_PTR_TO_MAP_KEY is one of such argument constraints. * It means that the register type passed to this function must be * PTR_TO_STACK and it will be used inside the function as * 'pointer to map element key' * * For example the argument constraints for bpf_map_lookup_elem(): * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, * .arg1_type = ARG_CONST_MAP_PTR, * .arg2_type = ARG_PTR_TO_MAP_KEY, * * ret_type says that this function returns 'pointer to map elem value or null' * function expects 1st argument to be a const pointer to 'struct bpf_map' and * 2nd argument should be a pointer to stack, which will be used inside * the helper function as a pointer to map element key. * * On the kernel side the helper function looks like: * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) * { * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; * void *key = (void *) (unsigned long) r2; * void *value; * * here kernel can access 'key' and 'map' pointers safely, knowing that * [key, key + map->key_size) bytes are valid and were initialized on * the stack of eBPF program. * } * * Corresponding eBPF program may look like: * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), * here verifier looks at prototype of map_lookup_elem() and sees: * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, * Now verifier knows that this map has key of R1->map_ptr->key_size bytes * * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, * Now verifier checks that [R2, R2 + map's key_size) are within stack limits * and were initialized prior to this call. * If it's ok, then verifier allows this BPF_CALL insn and looks at * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function * returns either pointer to map value or NULL. * * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' * insn, the register holding that pointer in the true branch changes state to * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false * branch. See check_cond_jmp_op(). * * After the call R0 is set to return type of the function and registers R1-R5 * are set to NOT_INIT to indicate that they are no longer readable. * * The following reference types represent a potential reference to a kernel * resource which, after first being allocated, must be checked and freed by * the BPF program: * - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET * * When the verifier sees a helper call return a reference type, it allocates a * pointer id for the reference and stores it in the current function state. * Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into * PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type * passes through a NULL-check conditional. For the branch wherein the state is * changed to CONST_IMM, the verifier releases the reference. * * For each helper function that allocates a reference, such as * bpf_sk_lookup_tcp(), there is a corresponding release function, such as * bpf_sk_release(). When a reference type passes into the release function, * the verifier also releases the reference. If any unchecked or unreleased * reference remains at the end of the program, the verifier rejects it. */ /* verifier_state + insn_idx are pushed to stack when branch is encountered */ struct bpf_verifier_stack_elem { /* verifier state is 'st' * before processing instruction 'insn_idx' * and after processing instruction 'prev_insn_idx' */ struct bpf_verifier_state st; int insn_idx; int prev_insn_idx; struct bpf_verifier_stack_elem *next; /* length of verifier log at the time this state was pushed on stack */ u32 log_pos; }; #define BPF_COMPLEXITY_LIMIT_JMP_SEQ 8192 #define BPF_COMPLEXITY_LIMIT_STATES 64 #define BPF_MAP_KEY_POISON (1ULL << 63) #define BPF_MAP_KEY_SEEN (1ULL << 62) #define BPF_GLOBAL_PERCPU_MA_MAX_SIZE 512 #define BPF_PRIV_STACK_MIN_SIZE 64 static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx); static int release_reference(struct bpf_verifier_env *env, int ref_obj_id); static void invalidate_non_owning_refs(struct bpf_verifier_env *env); static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env); static int ref_set_non_owning(struct bpf_verifier_env *env, struct bpf_reg_state *reg); static void specialize_kfunc(struct bpf_verifier_env *env, u32 func_id, u16 offset, unsigned long *addr); static bool is_trusted_reg(const struct bpf_reg_state *reg); static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux) { return aux->map_ptr_state.poison; } static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux) { return aux->map_ptr_state.unpriv; } static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux, struct bpf_map *map, bool unpriv, bool poison) { unpriv |= bpf_map_ptr_unpriv(aux); aux->map_ptr_state.unpriv = unpriv; aux->map_ptr_state.poison = poison; aux->map_ptr_state.map_ptr = map; } static bool bpf_map_key_poisoned(const struct bpf_insn_aux_data *aux) { return aux->map_key_state & BPF_MAP_KEY_POISON; } static bool bpf_map_key_unseen(const struct bpf_insn_aux_data *aux) { return !(aux->map_key_state & BPF_MAP_KEY_SEEN); } static u64 bpf_map_key_immediate(const struct bpf_insn_aux_data *aux) { return aux->map_key_state & ~(BPF_MAP_KEY_SEEN | BPF_MAP_KEY_POISON); } static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state) { bool poisoned = bpf_map_key_poisoned(aux); aux->map_key_state = state | BPF_MAP_KEY_SEEN | (poisoned ? BPF_MAP_KEY_POISON : 0ULL); } static bool bpf_helper_call(const struct bpf_insn *insn) { return insn->code == (BPF_JMP | BPF_CALL) && insn->src_reg == 0; } static bool bpf_pseudo_call(const struct bpf_insn *insn) { return insn->code == (BPF_JMP | BPF_CALL) && insn->src_reg == BPF_PSEUDO_CALL; } static bool bpf_pseudo_kfunc_call(const struct bpf_insn *insn) { return insn->code == (BPF_JMP | BPF_CALL) && insn->src_reg == BPF_PSEUDO_KFUNC_CALL; } struct bpf_call_arg_meta { struct bpf_map *map_ptr; bool raw_mode; bool pkt_access; u8 release_regno; int regno; int access_size; int mem_size; u64 msize_max_value; int ref_obj_id; int dynptr_id; int map_uid; int func_id; struct btf *btf; u32 btf_id; struct btf *ret_btf; u32 ret_btf_id; u32 subprogno; struct btf_field *kptr_field; }; struct bpf_kfunc_call_arg_meta { /* In parameters */ struct btf *btf; u32 func_id; u32 kfunc_flags; const struct btf_type *func_proto; const char *func_name; /* Out parameters */ u32 ref_obj_id; u8 release_regno; bool r0_rdonly; u32 ret_btf_id; u64 r0_size; u32 subprogno; struct { u64 value; bool found; } arg_constant; /* arg_{btf,btf_id,owning_ref} are used by kfunc-specific handling, * generally to pass info about user-defined local kptr types to later * verification logic * bpf_obj_drop/bpf_percpu_obj_drop * Record the local kptr type to be drop'd * bpf_refcount_acquire (via KF_ARG_PTR_TO_REFCOUNTED_KPTR arg type) * Record the local kptr type to be refcount_incr'd and use * arg_owning_ref to determine whether refcount_acquire should be * fallible */ struct btf *arg_btf; u32 arg_btf_id; bool arg_owning_ref; struct { struct btf_field *field; } arg_list_head; struct { struct btf_field *field; } arg_rbtree_root; struct { enum bpf_dynptr_type type; u32 id; u32 ref_obj_id; } initialized_dynptr; struct { u8 spi; u8 frameno; } iter; struct { struct bpf_map *ptr; int uid; } map; u64 mem_size; }; struct btf *btf_vmlinux; static const char *btf_type_name(const struct btf *btf, u32 id) { return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off); } static DEFINE_MUTEX(bpf_verifier_lock); static DEFINE_MUTEX(bpf_percpu_ma_lock); __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...) { struct bpf_verifier_env *env = private_data; va_list args; if (!bpf_verifier_log_needed(&env->log)) return; va_start(args, fmt); bpf_verifier_vlog(&env->log, fmt, args); va_end(args); } static void verbose_invalid_scalar(struct bpf_verifier_env *env, struct bpf_reg_state *reg, struct bpf_retval_range range, const char *ctx, const char *reg_name) { bool unknown = true; verbose(env, "%s the register %s has", ctx, reg_name); if (reg->smin_value > S64_MIN) { verbose(env, " smin=%lld", reg->smin_value); unknown = false; } if (reg->smax_value < S64_MAX) { verbose(env, " smax=%lld", reg->smax_value); unknown = false; } if (unknown) verbose(env, " unknown scalar value"); verbose(env, " should have been in [%d, %d]\n", range.minval, range.maxval); } static bool reg_not_null(const struct bpf_reg_state *reg) { enum bpf_reg_type type; type = reg->type; if (type_may_be_null(type)) return false; type = base_type(type); return type == PTR_TO_SOCKET || type == PTR_TO_TCP_SOCK || type == PTR_TO_MAP_VALUE || type == PTR_TO_MAP_KEY || type == PTR_TO_SOCK_COMMON || (type == PTR_TO_BTF_ID && is_trusted_reg(reg)) || type == PTR_TO_MEM; } static struct btf_record *reg_btf_record(const struct bpf_reg_state *reg) { struct btf_record *rec = NULL; struct btf_struct_meta *meta; if (reg->type == PTR_TO_MAP_VALUE) { rec = reg->map_ptr->record; } else if (type_is_ptr_alloc_obj(reg->type)) { meta = btf_find_struct_meta(reg->btf, reg->btf_id); if (meta) rec = meta->record; } return rec; } static bool subprog_is_global(const struct bpf_verifier_env *env, int subprog) { struct bpf_func_info_aux *aux = env->prog->aux->func_info_aux; return aux && aux[subprog].linkage == BTF_FUNC_GLOBAL; } static const char *subprog_name(const struct bpf_verifier_env *env, int subprog) { struct bpf_func_info *info; if (!env->prog->aux->func_info) return ""; info = &env->prog->aux->func_info[subprog]; return btf_type_name(env->prog->aux->btf, info->type_id); } static void mark_subprog_exc_cb(struct bpf_verifier_env *env, int subprog) { struct bpf_subprog_info *info = subprog_info(env, subprog); info->is_cb = true; info->is_async_cb = true; info->is_exception_cb = true; } static bool subprog_is_exc_cb(struct bpf_verifier_env *env, int subprog) { return subprog_info(env, subprog)->is_exception_cb; } static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg) { return btf_record_has_field(reg_btf_record(reg), BPF_SPIN_LOCK); } static bool type_is_rdonly_mem(u32 type) { return type & MEM_RDONLY; } static bool is_acquire_function(enum bpf_func_id func_id, const struct bpf_map *map) { enum bpf_map_type map_type = map ? map->map_type : BPF_MAP_TYPE_UNSPEC; if (func_id == BPF_FUNC_sk_lookup_tcp || func_id == BPF_FUNC_sk_lookup_udp || func_id == BPF_FUNC_skc_lookup_tcp || func_id == BPF_FUNC_ringbuf_reserve || func_id == BPF_FUNC_kptr_xchg) return true; if (func_id == BPF_FUNC_map_lookup_elem && (map_type == BPF_MAP_TYPE_SOCKMAP || map_type == BPF_MAP_TYPE_SOCKHASH)) return true; return false; } static bool is_ptr_cast_function(enum bpf_func_id func_id) { return func_id == BPF_FUNC_tcp_sock || func_id == BPF_FUNC_sk_fullsock || func_id == BPF_FUNC_skc_to_tcp_sock || func_id == BPF_FUNC_skc_to_tcp6_sock || func_id == BPF_FUNC_skc_to_udp6_sock || func_id == BPF_FUNC_skc_to_mptcp_sock || func_id == BPF_FUNC_skc_to_tcp_timewait_sock || func_id == BPF_FUNC_skc_to_tcp_request_sock; } static bool is_dynptr_ref_function(enum bpf_func_id func_id) { return func_id == BPF_FUNC_dynptr_data; } static bool is_sync_callback_calling_kfunc(u32 btf_id); static bool is_async_callback_calling_kfunc(u32 btf_id); static bool is_callback_calling_kfunc(u32 btf_id); static bool is_bpf_throw_kfunc(struct bpf_insn *insn); static bool is_bpf_wq_set_callback_impl_kfunc(u32 btf_id); static bool is_sync_callback_calling_function(enum bpf_func_id func_id) { return func_id == BPF_FUNC_for_each_map_elem || func_id == BPF_FUNC_find_vma || func_id == BPF_FUNC_loop || func_id == BPF_FUNC_user_ringbuf_drain; } static bool is_async_callback_calling_function(enum bpf_func_id func_id) { return func_id == BPF_FUNC_timer_set_callback; } static bool is_callback_calling_function(enum bpf_func_id func_id) { return is_sync_callback_calling_function(func_id) || is_async_callback_calling_function(func_id); } static bool is_sync_callback_calling_insn(struct bpf_insn *insn) { return (bpf_helper_call(insn) && is_sync_callback_calling_function(insn->imm)) || (bpf_pseudo_kfunc_call(insn) && is_sync_callback_calling_kfunc(insn->imm)); } static bool is_async_callback_calling_insn(struct bpf_insn *insn) { return (bpf_helper_call(insn) && is_async_callback_calling_function(insn->imm)) || (bpf_pseudo_kfunc_call(insn) && is_async_callback_calling_kfunc(insn->imm)); } static bool is_may_goto_insn(struct bpf_insn *insn) { return insn->code == (BPF_JMP | BPF_JCOND) && insn->src_reg == BPF_MAY_GOTO; } static bool is_may_goto_insn_at(struct bpf_verifier_env *env, int insn_idx) { return is_may_goto_insn(&env->prog->insnsi[insn_idx]); } static bool is_storage_get_function(enum bpf_func_id func_id) { return func_id == BPF_FUNC_sk_storage_get || func_id == BPF_FUNC_inode_storage_get || func_id == BPF_FUNC_task_storage_get || func_id == BPF_FUNC_cgrp_storage_get; } static bool helper_multiple_ref_obj_use(enum bpf_func_id func_id, const struct bpf_map *map) { int ref_obj_uses = 0; if (is_ptr_cast_function(func_id)) ref_obj_uses++; if (is_acquire_function(func_id, map)) ref_obj_uses++; if (is_dynptr_ref_function(func_id)) ref_obj_uses++; return ref_obj_uses > 1; } static bool is_cmpxchg_insn(const struct bpf_insn *insn) { return BPF_CLASS(insn->code) == BPF_STX && BPF_MODE(insn->code) == BPF_ATOMIC && insn->imm == BPF_CMPXCHG; } static int __get_spi(s32 off) { return (-off - 1) / BPF_REG_SIZE; } static struct bpf_func_state *func(struct bpf_verifier_env *env, const struct bpf_reg_state *reg) { struct bpf_verifier_state *cur = env->cur_state; return cur->frame[reg->frameno]; } static bool is_spi_bounds_valid(struct bpf_func_state *state, int spi, int nr_slots) { int allocated_slots = state->allocated_stack / BPF_REG_SIZE; /* We need to check that slots between [spi - nr_slots + 1, spi] are * within [0, allocated_stack). * * Please note that the spi grows downwards. For example, a dynptr * takes the size of two stack slots; the first slot will be at * spi and the second slot will be at spi - 1. */ return spi - nr_slots + 1 >= 0 && spi < allocated_slots; } static int stack_slot_obj_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg, const char *obj_kind, int nr_slots) { int off, spi; if (!tnum_is_const(reg->var_off)) { verbose(env, "%s has to be at a constant offset\n", obj_kind); return -EINVAL; } off = reg->off + reg->var_off.value; if (off % BPF_REG_SIZE) { verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off); return -EINVAL; } spi = __get_spi(off); if (spi + 1 < nr_slots) { verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off); return -EINVAL; } if (!is_spi_bounds_valid(func(env, reg), spi, nr_slots)) return -ERANGE; return spi; } static int dynptr_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { return stack_slot_obj_get_spi(env, reg, "dynptr", BPF_DYNPTR_NR_SLOTS); } static int iter_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int nr_slots) { return stack_slot_obj_get_spi(env, reg, "iter", nr_slots); } static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type) { switch (arg_type & DYNPTR_TYPE_FLAG_MASK) { case DYNPTR_TYPE_LOCAL: return BPF_DYNPTR_TYPE_LOCAL; case DYNPTR_TYPE_RINGBUF: return BPF_DYNPTR_TYPE_RINGBUF; case DYNPTR_TYPE_SKB: return BPF_DYNPTR_TYPE_SKB; case DYNPTR_TYPE_XDP: return BPF_DYNPTR_TYPE_XDP; default: return BPF_DYNPTR_TYPE_INVALID; } } static enum bpf_type_flag get_dynptr_type_flag(enum bpf_dynptr_type type) { switch (type) { case BPF_DYNPTR_TYPE_LOCAL: return DYNPTR_TYPE_LOCAL; case BPF_DYNPTR_TYPE_RINGBUF: return DYNPTR_TYPE_RINGBUF; case BPF_DYNPTR_TYPE_SKB: return DYNPTR_TYPE_SKB; case BPF_DYNPTR_TYPE_XDP: return DYNPTR_TYPE_XDP; default: return 0; } } static bool dynptr_type_refcounted(enum bpf_dynptr_type type) { return type == BPF_DYNPTR_TYPE_RINGBUF; } static void __mark_dynptr_reg(struct bpf_reg_state *reg, enum bpf_dynptr_type type, bool first_slot, int dynptr_id); static void __mark_reg_not_init(const struct bpf_verifier_env *env, struct bpf_reg_state *reg); static void mark_dynptr_stack_regs(struct bpf_verifier_env *env, struct bpf_reg_state *sreg1, struct bpf_reg_state *sreg2, enum bpf_dynptr_type type) { int id = ++env->id_gen; __mark_dynptr_reg(sreg1, type, true, id); __mark_dynptr_reg(sreg2, type, false, id); } static void mark_dynptr_cb_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, enum bpf_dynptr_type type) { __mark_dynptr_reg(reg, type, true, ++env->id_gen); } static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env, struct bpf_func_state *state, int spi); static int mark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg, enum bpf_arg_type arg_type, int insn_idx, int clone_ref_obj_id) { struct bpf_func_state *state = func(env, reg); enum bpf_dynptr_type type; int spi, i, err; spi = dynptr_get_spi(env, reg); if (spi < 0) return spi; /* We cannot assume both spi and spi - 1 belong to the same dynptr, * hence we need to call destroy_if_dynptr_stack_slot twice for both, * to ensure that for the following example: * [d1][d1][d2][d2] * spi 3 2 1 0 * So marking spi = 2 should lead to destruction of both d1 and d2. In * case they do belong to same dynptr, second call won't see slot_type * as STACK_DYNPTR and will simply skip destruction. */ err = destroy_if_dynptr_stack_slot(env, state, spi); if (err) return err; err = destroy_if_dynptr_stack_slot(env, state, spi - 1); if (err) return err; for (i = 0; i < BPF_REG_SIZE; i++) { state->stack[spi].slot_type[i] = STACK_DYNPTR; state->stack[spi - 1].slot_type[i] = STACK_DYNPTR; } type = arg_to_dynptr_type(arg_type); if (type == BPF_DYNPTR_TYPE_INVALID) return -EINVAL; mark_dynptr_stack_regs(env, &state->stack[spi].spilled_ptr, &state->stack[spi - 1].spilled_ptr, type); if (dynptr_type_refcounted(type)) { /* The id is used to track proper releasing */ int id; if (clone_ref_obj_id) id = clone_ref_obj_id; else id = acquire_reference_state(env, insn_idx); if (id < 0) return id; state->stack[spi].spilled_ptr.ref_obj_id = id; state->stack[spi - 1].spilled_ptr.ref_obj_id = id; } state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN; return 0; } static void invalidate_dynptr(struct bpf_verifier_env *env, struct bpf_func_state *state, int spi) { int i; for (i = 0; i < BPF_REG_SIZE; i++) { state->stack[spi].slot_type[i] = STACK_INVALID; state->stack[spi - 1].slot_type[i] = STACK_INVALID; } __mark_reg_not_init(env, &state->stack[spi].spilled_ptr); __mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr); /* Why do we need to set REG_LIVE_WRITTEN for STACK_INVALID slot? * * While we don't allow reading STACK_INVALID, it is still possible to * do <8 byte writes marking some but not all slots as STACK_MISC. Then, * helpers or insns can do partial read of that part without failing, * but check_stack_range_initialized, check_stack_read_var_off, and * check_stack_read_fixed_off will do mark_reg_read for all 8-bytes of * the slot conservatively. Hence we need to prevent those liveness * marking walks. * * This was not a problem before because STACK_INVALID is only set by * default (where the default reg state has its reg->parent as NULL), or * in clean_live_states after REG_LIVE_DONE (at which point * mark_reg_read won't walk reg->parent chain), but not randomly during * verifier state exploration (like we did above). Hence, for our case * parentage chain will still be live (i.e. reg->parent may be * non-NULL), while earlier reg->parent was NULL, so we need * REG_LIVE_WRITTEN to screen off read marker propagation when it is * done later on reads or by mark_dynptr_read as well to unnecessary * mark registers in verifier state. */ state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN; } static int unmark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { struct bpf_func_state *state = func(env, reg); int spi, ref_obj_id, i; spi = dynptr_get_spi(env, reg); if (spi < 0) return spi; if (!dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) { invalidate_dynptr(env, state, spi); return 0; } ref_obj_id = state->stack[spi].spilled_ptr.ref_obj_id; /* If the dynptr has a ref_obj_id, then we need to invalidate * two things: * * 1) Any dynptrs with a matching ref_obj_id (clones) * 2) Any slices derived from this dynptr. */ /* Invalidate any slices associated with this dynptr */ WARN_ON_ONCE(release_reference(env, ref_obj_id)); /* Invalidate any dynptr clones */ for (i = 1; i < state->allocated_stack / BPF_REG_SIZE; i++) { if (state->stack[i].spilled_ptr.ref_obj_id != ref_obj_id) continue; /* it should always be the case that if the ref obj id * matches then the stack slot also belongs to a * dynptr */ if (state->stack[i].slot_type[0] != STACK_DYNPTR) { verbose(env, "verifier internal error: misconfigured ref_obj_id\n"); return -EFAULT; } if (state->stack[i].spilled_ptr.dynptr.first_slot) invalidate_dynptr(env, state, i); } return 0; } static void __mark_reg_unknown(const struct bpf_verifier_env *env, struct bpf_reg_state *reg); static void mark_reg_invalid(const struct bpf_verifier_env *env, struct bpf_reg_state *reg) { if (!env->allow_ptr_leaks) __mark_reg_not_init(env, reg); else __mark_reg_unknown(env, reg); } static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env, struct bpf_func_state *state, int spi) { struct bpf_func_state *fstate; struct bpf_reg_state *dreg; int i, dynptr_id; /* We always ensure that STACK_DYNPTR is never set partially, * hence just checking for slot_type[0] is enough. This is * different for STACK_SPILL, where it may be only set for * 1 byte, so code has to use is_spilled_reg. */ if (state->stack[spi].slot_type[0] != STACK_DYNPTR) return 0; /* Reposition spi to first slot */ if (!state->stack[spi].spilled_ptr.dynptr.first_slot) spi = spi + 1; if (dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) { verbose(env, "cannot overwrite referenced dynptr\n"); return -EINVAL; } mark_stack_slot_scratched(env, spi); mark_stack_slot_scratched(env, spi - 1); /* Writing partially to one dynptr stack slot destroys both. */ for (i = 0; i < BPF_REG_SIZE; i++) { state->stack[spi].slot_type[i] = STACK_INVALID; state->stack[spi - 1].slot_type[i] = STACK_INVALID; } dynptr_id = state->stack[spi].spilled_ptr.id; /* Invalidate any slices associated with this dynptr */ bpf_for_each_reg_in_vstate(env->cur_state, fstate, dreg, ({ /* Dynptr slices are only PTR_TO_MEM_OR_NULL and PTR_TO_MEM */ if (dreg->type != (PTR_TO_MEM | PTR_MAYBE_NULL) && dreg->type != PTR_TO_MEM) continue; if (dreg->dynptr_id == dynptr_id) mark_reg_invalid(env, dreg); })); /* Do not release reference state, we are destroying dynptr on stack, * not using some helper to release it. Just reset register. */ __mark_reg_not_init(env, &state->stack[spi].spilled_ptr); __mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr); /* Same reason as unmark_stack_slots_dynptr above */ state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN; return 0; } static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { int spi; if (reg->type == CONST_PTR_TO_DYNPTR) return false; spi = dynptr_get_spi(env, reg); /* -ERANGE (i.e. spi not falling into allocated stack slots) isn't an * error because this just means the stack state hasn't been updated yet. * We will do check_mem_access to check and update stack bounds later. */ if (spi < 0 && spi != -ERANGE) return false; /* We don't need to check if the stack slots are marked by previous * dynptr initializations because we allow overwriting existing unreferenced * STACK_DYNPTR slots, see mark_stack_slots_dynptr which calls * destroy_if_dynptr_stack_slot to ensure dynptr objects at the slots we are * touching are completely destructed before we reinitialize them for a new * one. For referenced ones, destroy_if_dynptr_stack_slot returns an error early * instead of delaying it until the end where the user will get "Unreleased * reference" error. */ return true; } static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { struct bpf_func_state *state = func(env, reg); int i, spi; /* This already represents first slot of initialized bpf_dynptr. * * CONST_PTR_TO_DYNPTR already has fixed and var_off as 0 due to * check_func_arg_reg_off's logic, so we don't need to check its * offset and alignment. */ if (reg->type == CONST_PTR_TO_DYNPTR) return true; spi = dynptr_get_spi(env, reg); if (spi < 0) return false; if (!state->stack[spi].spilled_ptr.dynptr.first_slot) return false; for (i = 0; i < BPF_REG_SIZE; i++) { if (state->stack[spi].slot_type[i] != STACK_DYNPTR || state->stack[spi - 1].slot_type[i] != STACK_DYNPTR) return false; } return true; } static bool is_dynptr_type_expected(struct bpf_verifier_env *env, struct bpf_reg_state *reg, enum bpf_arg_type arg_type) { struct bpf_func_state *state = func(env, reg); enum bpf_dynptr_type dynptr_type; int spi; /* ARG_PTR_TO_DYNPTR takes any type of dynptr */ if (arg_type == ARG_PTR_TO_DYNPTR) return true; dynptr_type = arg_to_dynptr_type(arg_type); if (reg->type == CONST_PTR_TO_DYNPTR) { return reg->dynptr.type == dynptr_type; } else { spi = dynptr_get_spi(env, reg); if (spi < 0) return false; return state->stack[spi].spilled_ptr.dynptr.type == dynptr_type; } } static void __mark_reg_known_zero(struct bpf_reg_state *reg); static bool in_rcu_cs(struct bpf_verifier_env *env); static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta); static int mark_stack_slots_iter(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta, struct bpf_reg_state *reg, int insn_idx, struct btf *btf, u32 btf_id, int nr_slots) { struct bpf_func_state *state = func(env, reg); int spi, i, j, id; spi = iter_get_spi(env, reg, nr_slots); if (spi < 0) return spi; id = acquire_reference_state(env, insn_idx); if (id < 0) return id; for (i = 0; i < nr_slots; i++) { struct bpf_stack_state *slot = &state->stack[spi - i]; struct bpf_reg_state *st = &slot->spilled_ptr; __mark_reg_known_zero(st); st->type = PTR_TO_STACK; /* we don't have dedicated reg type */ if (is_kfunc_rcu_protected(meta)) { if (in_rcu_cs(env)) st->type |= MEM_RCU; else st->type |= PTR_UNTRUSTED; } st->live |= REG_LIVE_WRITTEN; st->ref_obj_id = i == 0 ? id : 0; st->iter.btf = btf; st->iter.btf_id = btf_id; st->iter.state = BPF_ITER_STATE_ACTIVE; st->iter.depth = 0; for (j = 0; j < BPF_REG_SIZE; j++) slot->slot_type[j] = STACK_ITER; mark_stack_slot_scratched(env, spi - i); } return 0; } static int unmark_stack_slots_iter(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int nr_slots) { struct bpf_func_state *state = func(env, reg); int spi, i, j; spi = iter_get_spi(env, reg, nr_slots); if (spi < 0) return spi; for (i = 0; i < nr_slots; i++) { struct bpf_stack_state *slot = &state->stack[spi - i]; struct bpf_reg_state *st = &slot->spilled_ptr; if (i == 0) WARN_ON_ONCE(release_reference(env, st->ref_obj_id)); __mark_reg_not_init(env, st); /* see unmark_stack_slots_dynptr() for why we need to set REG_LIVE_WRITTEN */ st->live |= REG_LIVE_WRITTEN; for (j = 0; j < BPF_REG_SIZE; j++) slot->slot_type[j] = STACK_INVALID; mark_stack_slot_scratched(env, spi - i); } return 0; } static bool is_iter_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int nr_slots) { struct bpf_func_state *state = func(env, reg); int spi, i, j; /* For -ERANGE (i.e. spi not falling into allocated stack slots), we * will do check_mem_access to check and update stack bounds later, so * return true for that case. */ spi = iter_get_spi(env, reg, nr_slots); if (spi == -ERANGE) return true; if (spi < 0) return false; for (i = 0; i < nr_slots; i++) { struct bpf_stack_state *slot = &state->stack[spi - i]; for (j = 0; j < BPF_REG_SIZE; j++) if (slot->slot_type[j] == STACK_ITER) return false; } return true; } static int is_iter_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg, struct btf *btf, u32 btf_id, int nr_slots) { struct bpf_func_state *state = func(env, reg); int spi, i, j; spi = iter_get_spi(env, reg, nr_slots); if (spi < 0) return -EINVAL; for (i = 0; i < nr_slots; i++) { struct bpf_stack_state *slot = &state->stack[spi - i]; struct bpf_reg_state *st = &slot->spilled_ptr; if (st->type & PTR_UNTRUSTED) return -EPROTO; /* only main (first) slot has ref_obj_id set */ if (i == 0 && !st->ref_obj_id) return -EINVAL; if (i != 0 && st->ref_obj_id) return -EINVAL; if (st->iter.btf != btf || st->iter.btf_id != btf_id) return -EINVAL; for (j = 0; j < BPF_REG_SIZE; j++) if (slot->slot_type[j] != STACK_ITER) return -EINVAL; } return 0; } /* Check if given stack slot is "special": * - spilled register state (STACK_SPILL); * - dynptr state (STACK_DYNPTR); * - iter state (STACK_ITER). */ static bool is_stack_slot_special(const struct bpf_stack_state *stack) { enum bpf_stack_slot_type type = stack->slot_type[BPF_REG_SIZE - 1]; switch (type) { case STACK_SPILL: case STACK_DYNPTR: case STACK_ITER: return true; case STACK_INVALID: case STACK_MISC: case STACK_ZERO: return false; default: WARN_ONCE(1, "unknown stack slot type %d\n", type); return true; } } /* The reg state of a pointer or a bounded scalar was saved when * it was spilled to the stack. */ static bool is_spilled_reg(const struct bpf_stack_state *stack) { return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL; } static bool is_spilled_scalar_reg(const struct bpf_stack_state *stack) { return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL && stack->spilled_ptr.type == SCALAR_VALUE; } static bool is_spilled_scalar_reg64(const struct bpf_stack_state *stack) { return stack->slot_type[0] == STACK_SPILL && stack->spilled_ptr.type == SCALAR_VALUE; } /* Mark stack slot as STACK_MISC, unless it is already STACK_INVALID, in which * case they are equivalent, or it's STACK_ZERO, in which case we preserve * more precise STACK_ZERO. * Regardless of allow_ptr_leaks setting (i.e., privileged or unprivileged * mode), we won't promote STACK_INVALID to STACK_MISC. In privileged case it is * unnecessary as both are considered equivalent when loading data and pruning, * in case of unprivileged mode it will be incorrect to allow reads of invalid * slots. */ static void mark_stack_slot_misc(struct bpf_verifier_env *env, u8 *stype) { if (*stype == STACK_ZERO) return; if (*stype == STACK_INVALID) return; *stype = STACK_MISC; } static void scrub_spilled_slot(u8 *stype) { if (*stype != STACK_INVALID) *stype = STACK_MISC; } /* copy array src of length n * size bytes to dst. dst is reallocated if it's too * small to hold src. This is different from krealloc since we don't want to preserve * the contents of dst. * * Leaves dst untouched if src is NULL or length is zero. Returns NULL if memory could * not be allocated. */ static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t flags) { size_t alloc_bytes; void *orig = dst; size_t bytes; if (ZERO_OR_NULL_PTR(src)) goto out; if (unlikely(check_mul_overflow(n, size, &bytes))) return NULL; alloc_bytes = max(ksize(orig), kmalloc_size_roundup(bytes)); dst = krealloc(orig, alloc_bytes, flags); if (!dst) { kfree(orig); return NULL; } memcpy(dst, src, bytes); out: return dst ? dst : ZERO_SIZE_PTR; } /* resize an array from old_n items to new_n items. the array is reallocated if it's too * small to hold new_n items. new items are zeroed out if the array grows. * * Contrary to krealloc_array, does not free arr if new_n is zero. */ static void *realloc_array(void *arr, size_t old_n, size_t new_n, size_t size) { size_t alloc_size; void *new_arr; if (!new_n || old_n == new_n) goto out; alloc_size = kmalloc_size_roundup(size_mul(new_n, size)); new_arr = krealloc(arr, alloc_size, GFP_KERNEL); if (!new_arr) { kfree(arr); return NULL; } arr = new_arr; if (new_n > old_n) memset(arr + old_n * size, 0, (new_n - old_n) * size); out: return arr ? arr : ZERO_SIZE_PTR; } static int copy_reference_state(struct bpf_func_state *dst, const struct bpf_func_state *src) { dst->refs = copy_array(dst->refs, src->refs, src->acquired_refs, sizeof(struct bpf_reference_state), GFP_KERNEL); if (!dst->refs) return -ENOMEM; dst->active_locks = src->active_locks; dst->acquired_refs = src->acquired_refs; return 0; } static int copy_stack_state(struct bpf_func_state *dst, const struct bpf_func_state *src) { size_t n = src->allocated_stack / BPF_REG_SIZE; dst->stack = copy_array(dst->stack, src->stack, n, sizeof(struct bpf_stack_state), GFP_KERNEL); if (!dst->stack) return -ENOMEM; dst->allocated_stack = src->allocated_stack; return 0; } static int resize_reference_state(struct bpf_func_state *state, size_t n) { state->refs = realloc_array(state->refs, state->acquired_refs, n, sizeof(struct bpf_reference_state)); if (!state->refs) return -ENOMEM; state->acquired_refs = n; return 0; } /* Possibly update state->allocated_stack to be at least size bytes. Also * possibly update the function's high-water mark in its bpf_subprog_info. */ static int grow_stack_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int size) { size_t old_n = state->allocated_stack / BPF_REG_SIZE, n; /* The stack size is always a multiple of BPF_REG_SIZE. */ size = round_up(size, BPF_REG_SIZE); n = size / BPF_REG_SIZE; if (old_n >= n) return 0; state->stack = realloc_array(state->stack, old_n, n, sizeof(struct bpf_stack_state)); if (!state->stack) return -ENOMEM; state->allocated_stack = size; /* update known max for given subprogram */ if (env->subprog_info[state->subprogno].stack_depth < size) env->subprog_info[state->subprogno].stack_depth = size; return 0; } /* Acquire a pointer id from the env and update the state->refs to include * this new pointer reference. * On success, returns a valid pointer id to associate with the register * On failure, returns a negative errno. */ static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx) { struct bpf_func_state *state = cur_func(env); int new_ofs = state->acquired_refs; int id, err; err = resize_reference_state(state, state->acquired_refs + 1); if (err) return err; id = ++env->id_gen; state->refs[new_ofs].type = REF_TYPE_PTR; state->refs[new_ofs].id = id; state->refs[new_ofs].insn_idx = insn_idx; return id; } static int acquire_lock_state(struct bpf_verifier_env *env, int insn_idx, enum ref_state_type type, int id, void *ptr) { struct bpf_func_state *state = cur_func(env); int new_ofs = state->acquired_refs; int err; err = resize_reference_state(state, state->acquired_refs + 1); if (err) return err; state->refs[new_ofs].type = type; state->refs[new_ofs].id = id; state->refs[new_ofs].insn_idx = insn_idx; state->refs[new_ofs].ptr = ptr; state->active_locks++; return 0; } /* release function corresponding to acquire_reference_state(). Idempotent. */ static int release_reference_state(struct bpf_func_state *state, int ptr_id) { int i, last_idx; last_idx = state->acquired_refs - 1; for (i = 0; i < state->acquired_refs; i++) { if (state->refs[i].type != REF_TYPE_PTR) continue; if (state->refs[i].id == ptr_id) { if (last_idx && i != last_idx) memcpy(&state->refs[i], &state->refs[last_idx], sizeof(*state->refs)); memset(&state->refs[last_idx], 0, sizeof(*state->refs)); state->acquired_refs--; return 0; } } return -EINVAL; } static int release_lock_state(struct bpf_func_state *state, int type, int id, void *ptr) { int i, last_idx; last_idx = state->acquired_refs - 1; for (i = 0; i < state->acquired_refs; i++) { if (state->refs[i].type != type) continue; if (state->refs[i].id == id && state->refs[i].ptr == ptr) { if (last_idx && i != last_idx) memcpy(&state->refs[i], &state->refs[last_idx], sizeof(*state->refs)); memset(&state->refs[last_idx], 0, sizeof(*state->refs)); state->acquired_refs--; state->active_locks--; return 0; } } return -EINVAL; } static struct bpf_reference_state *find_lock_state(struct bpf_verifier_env *env, enum ref_state_type type, int id, void *ptr) { struct bpf_func_state *state = cur_func(env); int i; for (i = 0; i < state->acquired_refs; i++) { struct bpf_reference_state *s = &state->refs[i]; if (s->type == REF_TYPE_PTR || s->type != type) continue; if (s->id == id && s->ptr == ptr) return s; } return NULL; } static void free_func_state(struct bpf_func_state *state) { if (!state) return; kfree(state->refs); kfree(state->stack); kfree(state); } static void free_verifier_state(struct bpf_verifier_state *state, bool free_self) { int i; for (i = 0; i <= state->curframe; i++) { free_func_state(state->frame[i]); state->frame[i] = NULL; } if (free_self) kfree(state); } /* copy verifier state from src to dst growing dst stack space * when necessary to accommodate larger src stack */ static int copy_func_state(struct bpf_func_state *dst, const struct bpf_func_state *src) { int err; memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs)); err = copy_reference_state(dst, src); if (err) return err; return copy_stack_state(dst, src); } static int copy_verifier_state(struct bpf_verifier_state *dst_state, const struct bpf_verifier_state *src) { struct bpf_func_state *dst; int i, err; /* if dst has more stack frames then src frame, free them, this is also * necessary in case of exceptional exits using bpf_throw. */ for (i = src->curframe + 1; i <= dst_state->curframe; i++) { free_func_state(dst_state->frame[i]); dst_state->frame[i] = NULL; } dst_state->speculative = src->speculative; dst_state->active_rcu_lock = src->active_rcu_lock; dst_state->active_preempt_lock = src->active_preempt_lock; dst_state->in_sleepable = src->in_sleepable; dst_state->curframe = src->curframe; dst_state->branches = src->branches; dst_state->parent = src->parent; dst_state->first_insn_idx = src->first_insn_idx; dst_state->last_insn_idx = src->last_insn_idx; dst_state->insn_hist_start = src->insn_hist_start; dst_state->insn_hist_end = src->insn_hist_end; dst_state->dfs_depth = src->dfs_depth; dst_state->callback_unroll_depth = src->callback_unroll_depth; dst_state->used_as_loop_entry = src->used_as_loop_entry; dst_state->may_goto_depth = src->may_goto_depth; for (i = 0; i <= src->curframe; i++) { dst = dst_state->frame[i]; if (!dst) { dst = kzalloc(sizeof(*dst), GFP_KERNEL); if (!dst) return -ENOMEM; dst_state->frame[i] = dst; } err = copy_func_state(dst, src->frame[i]); if (err) return err; } return 0; } static u32 state_htab_size(struct bpf_verifier_env *env) { return env->prog->len; } static struct bpf_verifier_state_list **explored_state(struct bpf_verifier_env *env, int idx) { struct bpf_verifier_state *cur = env->cur_state; struct bpf_func_state *state = cur->frame[cur->curframe]; return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)]; } static bool same_callsites(struct bpf_verifier_state *a, struct bpf_verifier_state *b) { int fr; if (a->curframe != b->curframe) return false; for (fr = a->curframe; fr >= 0; fr--) if (a->frame[fr]->callsite != b->frame[fr]->callsite) return false; return true; } /* Open coded iterators allow back-edges in the state graph in order to * check unbounded loops that iterators. * * In is_state_visited() it is necessary to know if explored states are * part of some loops in order to decide whether non-exact states * comparison could be used: * - non-exact states comparison establishes sub-state relation and uses * read and precision marks to do so, these marks are propagated from * children states and thus are not guaranteed to be final in a loop; * - exact states comparison just checks if current and explored states * are identical (and thus form a back-edge). * * Paper "A New Algorithm for Identifying Loops in Decompilation" * by Tao Wei, Jian Mao, Wei Zou and Yu Chen [1] presents a convenient * algorithm for loop structure detection and gives an overview of * relevant terminology. It also has helpful illustrations. * * [1] https://api.semanticscholar.org/CorpusID:15784067 * * We use a similar algorithm but because loop nested structure is * irrelevant for verifier ours is significantly simpler and resembles * strongly connected components algorithm from Sedgewick's textbook. * * Define topmost loop entry as a first node of the loop traversed in a * depth first search starting from initial state. The goal of the loop * tracking algorithm is to associate topmost loop entries with states * derived from these entries. * * For each step in the DFS states traversal algorithm needs to identify * the following situations: * * initial initial initial * | | | * V V V * ... ... .---------> hdr * | | | | * V V | V * cur .-> succ | .------... * | | | | | | * V | V | V V * succ '-- cur | ... ... * | | | * | V V * | succ <- cur * | | * | V * | ... * | | * '----' * * (A) successor state of cur (B) successor state of cur or it's entry * not yet traversed are in current DFS path, thus cur and succ * are members of the same outermost loop * * initial initial * | | * V V * ... ... * | | * V V * .------... .------... * | | | | * V V V V * .-> hdr ... ... ... * | | | | | * | V V V V * | succ <- cur succ <- cur * | | | * | V V * | ... ... * | | | * '----' exit * * (C) successor state of cur is a part of some loop but this loop * does not include cur or successor state is not in a loop at all. * * Algorithm could be described as the following python code: * * traversed = set() # Set of traversed nodes * entries = {} # Mapping from node to loop entry * depths = {} # Depth level assigned to graph node * path = set() # Current DFS path * * # Find outermost loop entry known for n * def get_loop_entry(n): * h = entries.get(n, None) * while h in entries and entries[h] != h: * h = entries[h] * return h * * # Update n's loop entry if h's outermost entry comes * # before n's outermost entry in current DFS path. * def update_loop_entry(n, h): * n1 = get_loop_entry(n) or n * h1 = get_loop_entry(h) or h * if h1 in path and depths[h1] <= depths[n1]: * entries[n] = h1 * * def dfs(n, depth): * traversed.add(n) * path.add(n) * depths[n] = depth * for succ in G.successors(n): * if succ not in traversed: * # Case A: explore succ and update cur's loop entry * # only if succ's entry is in current DFS path. * dfs(succ, depth + 1) * h = get_loop_entry(succ) * update_loop_entry(n, h) * else: * # Case B or C depending on `h1 in path` check in update_loop_entry(). * update_loop_entry(n, succ) * path.remove(n) * * To adapt this algorithm for use with verifier: * - use st->branch == 0 as a signal that DFS of succ had been finished * and cur's loop entry has to be updated (case A), handle this in * update_branch_counts(); * - use st->branch > 0 as a signal that st is in the current DFS path; * - handle cases B and C in is_state_visited(); * - update topmost loop entry for intermediate states in get_loop_entry(). */ static struct bpf_verifier_state *get_loop_entry(struct bpf_verifier_state *st) { struct bpf_verifier_state *topmost = st->loop_entry, *old; while (topmost && topmost->loop_entry && topmost != topmost->loop_entry) topmost = topmost->loop_entry; /* Update loop entries for intermediate states to avoid this * traversal in future get_loop_entry() calls. */ while (st && st->loop_entry != topmost) { old = st->loop_entry; st->loop_entry = topmost; st = old; } return topmost; } static void update_loop_entry(struct bpf_verifier_state *cur, struct bpf_verifier_state *hdr) { struct bpf_verifier_state *cur1, *hdr1; cur1 = get_loop_entry(cur) ?: cur; hdr1 = get_loop_entry(hdr) ?: hdr; /* The head1->branches check decides between cases B and C in * comment for get_loop_entry(). If hdr1->branches == 0 then * head's topmost loop entry is not in current DFS path, * hence 'cur' and 'hdr' are not in the same loop and there is * no need to update cur->loop_entry. */ if (hdr1->branches && hdr1->dfs_depth <= cur1->dfs_depth) { cur->loop_entry = hdr; hdr->used_as_loop_entry = true; } } static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st) { while (st) { u32 br = --st->branches; /* br == 0 signals that DFS exploration for 'st' is finished, * thus it is necessary to update parent's loop entry if it * turned out that st is a part of some loop. * This is a part of 'case A' in get_loop_entry() comment. */ if (br == 0 && st->parent && st->loop_entry) update_loop_entry(st->parent, st->loop_entry); /* WARN_ON(br > 1) technically makes sense here, * but see comment in push_stack(), hence: */ WARN_ONCE((int)br < 0, "BUG update_branch_counts:branches_to_explore=%d\n", br); if (br) break; st = st->parent; } } static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx, int *insn_idx, bool pop_log) { struct bpf_verifier_state *cur = env->cur_state; struct bpf_verifier_stack_elem *elem, *head = env->head; int err; if (env->head == NULL) return -ENOENT; if (cur) { err = copy_verifier_state(cur, &head->st); if (err) return err; } if (pop_log) bpf_vlog_reset(&env->log, head->log_pos); if (insn_idx) *insn_idx = head->insn_idx; if (prev_insn_idx) *prev_insn_idx = head->prev_insn_idx; elem = head->next; free_verifier_state(&head->st, false); kfree(head); env->head = elem; env->stack_size--; return 0; } static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx, bool speculative) { struct bpf_verifier_state *cur = env->cur_state; struct bpf_verifier_stack_elem *elem; int err; elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); if (!elem) goto err; elem->insn_idx = insn_idx; elem->prev_insn_idx = prev_insn_idx; elem->next = env->head; elem->log_pos = env->log.end_pos; env->head = elem; env->stack_size++; err = copy_verifier_state(&elem->st, cur); if (err) goto err; elem->st.speculative |= speculative; if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) { verbose(env, "The sequence of %d jumps is too complex.\n", env->stack_size); goto err; } if (elem->st.parent) { ++elem->st.parent->branches; /* WARN_ON(branches > 2) technically makes sense here, * but * 1. speculative states will bump 'branches' for non-branch * instructions * 2. is_state_visited() heuristics may decide not to create * a new state for a sequence of branches and all such current * and cloned states will be pointing to a single parent state * which might have large 'branches' count. */ } return &elem->st; err: free_verifier_state(env->cur_state, true); env->cur_state = NULL; /* pop all elements and return */ while (!pop_stack(env, NULL, NULL, false)); return NULL; } #define CALLER_SAVED_REGS 6 static const int caller_saved[CALLER_SAVED_REGS] = { BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 }; /* This helper doesn't clear reg->id */ static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm) { reg->var_off = tnum_const(imm); reg->smin_value = (s64)imm; reg->smax_value = (s64)imm; reg->umin_value = imm; reg->umax_value = imm; reg->s32_min_value = (s32)imm; reg->s32_max_value = (s32)imm; reg->u32_min_value = (u32)imm; reg->u32_max_value = (u32)imm; } /* Mark the unknown part of a register (variable offset or scalar value) as * known to have the value @imm. */ static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm) { /* Clear off and union(map_ptr, range) */ memset(((u8 *)reg) + sizeof(reg->type), 0, offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type)); reg->id = 0; reg->ref_obj_id = 0; ___mark_reg_known(reg, imm); } static void __mark_reg32_known(struct bpf_reg_state *reg, u64 imm) { reg->var_off = tnum_const_subreg(reg->var_off, imm); reg->s32_min_value = (s32)imm; reg->s32_max_value = (s32)imm; reg->u32_min_value = (u32)imm; reg->u32_max_value = (u32)imm; } /* Mark the 'variable offset' part of a register as zero. This should be * used only on registers holding a pointer type. */ static void __mark_reg_known_zero(struct bpf_reg_state *reg) { __mark_reg_known(reg, 0); } static void __mark_reg_const_zero(const struct bpf_verifier_env *env, struct bpf_reg_state *reg) { __mark_reg_known(reg, 0); reg->type = SCALAR_VALUE; /* all scalars are assumed imprecise initially (unless unprivileged, * in which case everything is forced to be precise) */ reg->precise = !env->bpf_capable; } static void mark_reg_known_zero(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno) { if (WARN_ON(regno >= MAX_BPF_REG)) { verbose(env, "mark_reg_known_zero(regs, %u)\n", regno); /* Something bad happened, let's kill all regs */ for (regno = 0; regno < MAX_BPF_REG; regno++) __mark_reg_not_init(env, regs + regno); return; } __mark_reg_known_zero(regs + regno); } static void __mark_dynptr_reg(struct bpf_reg_state *reg, enum bpf_dynptr_type type, bool first_slot, int dynptr_id) { /* reg->type has no meaning for STACK_DYNPTR, but when we set reg for * callback arguments, it does need to be CONST_PTR_TO_DYNPTR, so simply * set it unconditionally as it is ignored for STACK_DYNPTR anyway. */ __mark_reg_known_zero(reg); reg->type = CONST_PTR_TO_DYNPTR; /* Give each dynptr a unique id to uniquely associate slices to it. */ reg->id = dynptr_id; reg->dynptr.type = type; reg->dynptr.first_slot = first_slot; } static void mark_ptr_not_null_reg(struct bpf_reg_state *reg) { if (base_type(reg->type) == PTR_TO_MAP_VALUE) { const struct bpf_map *map = reg->map_ptr; if (map->inner_map_meta) { reg->type = CONST_PTR_TO_MAP; reg->map_ptr = map->inner_map_meta; /* transfer reg's id which is unique for every map_lookup_elem * as UID of the inner map. */ if (btf_record_has_field(map->inner_map_meta->record, BPF_TIMER)) reg->map_uid = reg->id; if (btf_record_has_field(map->inner_map_meta->record, BPF_WORKQUEUE)) reg->map_uid = reg->id; } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) { reg->type = PTR_TO_XDP_SOCK; } else if (map->map_type == BPF_MAP_TYPE_SOCKMAP || map->map_type == BPF_MAP_TYPE_SOCKHASH) { reg->type = PTR_TO_SOCKET; } else { reg->type = PTR_TO_MAP_VALUE; } return; } reg->type &= ~PTR_MAYBE_NULL; } static void mark_reg_graph_node(struct bpf_reg_state *regs, u32 regno, struct btf_field_graph_root *ds_head) { __mark_reg_known_zero(®s[regno]); regs[regno].type = PTR_TO_BTF_ID | MEM_ALLOC; regs[regno].btf = ds_head->btf; regs[regno].btf_id = ds_head->value_btf_id; regs[regno].off = ds_head->node_offset; } static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg) { return type_is_pkt_pointer(reg->type); } static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg) { return reg_is_pkt_pointer(reg) || reg->type == PTR_TO_PACKET_END; } static bool reg_is_dynptr_slice_pkt(const struct bpf_reg_state *reg) { return base_type(reg->type) == PTR_TO_MEM && (reg->type & DYNPTR_TYPE_SKB || reg->type & DYNPTR_TYPE_XDP); } /* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */ static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg, enum bpf_reg_type which) { /* The register can already have a range from prior markings. * This is fine as long as it hasn't been advanced from its * origin. */ return reg->type == which && reg->id == 0 && reg->off == 0 && tnum_equals_const(reg->var_off, 0); } /* Reset the min/max bounds of a register */ static void __mark_reg_unbounded(struct bpf_reg_state *reg) { reg->smin_value = S64_MIN; reg->smax_value = S64_MAX; reg->umin_value = 0; reg->umax_value = U64_MAX; reg->s32_min_value = S32_MIN; reg->s32_max_value = S32_MAX; reg->u32_min_value = 0; reg->u32_max_value = U32_MAX; } static void __mark_reg64_unbounded(struct bpf_reg_state *reg) { reg->smin_value = S64_MIN; reg->smax_value = S64_MAX; reg->umin_value = 0; reg->umax_value = U64_MAX; } static void __mark_reg32_unbounded(struct bpf_reg_state *reg) { reg->s32_min_value = S32_MIN; reg->s32_max_value = S32_MAX; reg->u32_min_value = 0; reg->u32_max_value = U32_MAX; } static void __update_reg32_bounds(struct bpf_reg_state *reg) { struct tnum var32_off = tnum_subreg(reg->var_off); /* min signed is max(sign bit) | min(other bits) */ reg->s32_min_value = max_t(s32, reg->s32_min_value, var32_off.value | (var32_off.mask & S32_MIN)); /* max signed is min(sign bit) | max(other bits) */ reg->s32_max_value = min_t(s32, reg->s32_max_value, var32_off.value | (var32_off.mask & S32_MAX)); reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value); reg->u32_max_value = min(reg->u32_max_value, (u32)(var32_off.value | var32_off.mask)); } static void __update_reg64_bounds(struct bpf_reg_state *reg) { /* min signed is max(sign bit) | min(other bits) */ reg->smin_value = max_t(s64, reg->smin_value, reg->var_off.value | (reg->var_off.mask & S64_MIN)); /* max signed is min(sign bit) | max(other bits) */ reg->smax_value = min_t(s64, reg->smax_value, reg->var_off.value | (reg->var_off.mask & S64_MAX)); reg->umin_value = max(reg->umin_value, reg->var_off.value); reg->umax_value = min(reg->umax_value, reg->var_off.value | reg->var_off.mask); } static void __update_reg_bounds(struct bpf_reg_state *reg) { __update_reg32_bounds(reg); __update_reg64_bounds(reg); } /* Uses signed min/max values to inform unsigned, and vice-versa */ static void __reg32_deduce_bounds(struct bpf_reg_state *reg) { /* If upper 32 bits of u64/s64 range don't change, we can use lower 32 * bits to improve our u32/s32 boundaries. * * E.g., the case where we have upper 32 bits as zero ([10, 20] in * u64) is pretty trivial, it's obvious that in u32 we'll also have * [10, 20] range. But this property holds for any 64-bit range as * long as upper 32 bits in that entire range of values stay the same. * * E.g., u64 range [0x10000000A, 0x10000000F] ([4294967306, 4294967311] * in decimal) has the same upper 32 bits throughout all the values in * that range. As such, lower 32 bits form a valid [0xA, 0xF] ([10, 15]) * range. * * Note also, that [0xA, 0xF] is a valid range both in u32 and in s32, * following the rules outlined below about u64/s64 correspondence * (which equally applies to u32 vs s32 correspondence). In general it * depends on actual hexadecimal values of 32-bit range. They can form * only valid u32, or only valid s32 ranges in some cases. * * So we use all these insights to derive bounds for subregisters here. */ if ((reg->umin_value >> 32) == (reg->umax_value >> 32)) { /* u64 to u32 casting preserves validity of low 32 bits as * a range, if upper 32 bits are the same */ reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->umin_value); reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->umax_value); if ((s32)reg->umin_value <= (s32)reg->umax_value) { reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value); reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value); } } if ((reg->smin_value >> 32) == (reg->smax_value >> 32)) { /* low 32 bits should form a proper u32 range */ if ((u32)reg->smin_value <= (u32)reg->smax_value) { reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->smin_value); reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->smax_value); } /* low 32 bits should form a proper s32 range */ if ((s32)reg->smin_value <= (s32)reg->smax_value) { reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value); reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value); } } /* Special case where upper bits form a small sequence of two * sequential numbers (in 32-bit unsigned space, so 0xffffffff to * 0x00000000 is also valid), while lower bits form a proper s32 range * going from negative numbers to positive numbers. E.g., let's say we * have s64 range [-1, 1] ([0xffffffffffffffff, 0x0000000000000001]). * Possible s64 values are {-1, 0, 1} ({0xffffffffffffffff, * 0x0000000000000000, 0x00000000000001}). Ignoring upper 32 bits, * we still get a valid s32 range [-1, 1] ([0xffffffff, 0x00000001]). * Note that it doesn't have to be 0xffffffff going to 0x00000000 in * upper 32 bits. As a random example, s64 range * [0xfffffff0fffffff0; 0xfffffff100000010], forms a valid s32 range * [-16, 16] ([0xfffffff0; 0x00000010]) in its 32 bit subregister. */ if ((u32)(reg->umin_value >> 32) + 1 == (u32)(reg->umax_value >> 32) && (s32)reg->umin_value < 0 && (s32)reg->umax_value >= 0) { reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value); reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value); } if ((u32)(reg->smin_value >> 32) + 1 == (u32)(reg->smax_value >> 32) && (s32)reg->smin_value < 0 && (s32)reg->smax_value >= 0) { reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value); reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value); } /* if u32 range forms a valid s32 range (due to matching sign bit), * try to learn from that */ if ((s32)reg->u32_min_value <= (s32)reg->u32_max_value) { reg->s32_min_value = max_t(s32, reg->s32_min_value, reg->u32_min_value); reg->s32_max_value = min_t(s32, reg->s32_max_value, reg->u32_max_value); } /* If we cannot cross the sign boundary, then signed and unsigned bounds * are the same, so combine. This works even in the negative case, e.g. * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff. */ if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) { reg->u32_min_value = max_t(u32, reg->s32_min_value, reg->u32_min_value); reg->u32_max_value = min_t(u32, reg->s32_max_value, reg->u32_max_value); } } static void __reg64_deduce_bounds(struct bpf_reg_state *reg) { /* If u64 range forms a valid s64 range (due to matching sign bit), * try to learn from that. Let's do a bit of ASCII art to see when * this is happening. Let's take u64 range first: * * 0 0x7fffffffffffffff 0x8000000000000000 U64_MAX * |-------------------------------|--------------------------------| * * Valid u64 range is formed when umin and umax are anywhere in the * range [0, U64_MAX], and umin <= umax. u64 case is simple and * straightforward. Let's see how s64 range maps onto the same range * of values, annotated below the line for comparison: * * 0 0x7fffffffffffffff 0x8000000000000000 U64_MAX * |-------------------------------|--------------------------------| * 0 S64_MAX S64_MIN -1 * * So s64 values basically start in the middle and they are logically * contiguous to the right of it, wrapping around from -1 to 0, and * then finishing as S64_MAX (0x7fffffffffffffff) right before * S64_MIN. We can try drawing the continuity of u64 vs s64 values * more visually as mapped to sign-agnostic range of hex values. * * u64 start u64 end * _______________________________________________________________ * / \ * 0 0x7fffffffffffffff 0x8000000000000000 U64_MAX * |-------------------------------|--------------------------------| * 0 S64_MAX S64_MIN -1 * / \ * >------------------------------ -------------------------------> * s64 continues... s64 end s64 start s64 "midpoint" * * What this means is that, in general, we can't always derive * something new about u64 from any random s64 range, and vice versa. * * But we can do that in two particular cases. One is when entire * u64/s64 range is *entirely* contained within left half of the above * diagram or when it is *entirely* contained in the right half. I.e.: * * |-------------------------------|--------------------------------| * ^ ^ ^ ^ * A B C D * * [A, B] and [C, D] are contained entirely in their respective halves * and form valid contiguous ranges as both u64 and s64 values. [A, B] * will be non-negative both as u64 and s64 (and in fact it will be * identical ranges no matter the signedness). [C, D] treated as s64 * will be a range of negative values, while in u64 it will be * non-negative range of values larger than 0x8000000000000000. * * Now, any other range here can't be represented in both u64 and s64 * simultaneously. E.g., [A, C], [A, D], [B, C], [B, D] are valid * contiguous u64 ranges, but they are discontinuous in s64. [B, C] * in s64 would be properly presented as [S64_MIN, C] and [B, S64_MAX], * for example. Similarly, valid s64 range [D, A] (going from negative * to positive values), would be two separate [D, U64_MAX] and [0, A] * ranges as u64. Currently reg_state can't represent two segments per * numeric domain, so in such situations we can only derive maximal * possible range ([0, U64_MAX] for u64, and [S64_MIN, S64_MAX] for s64). * * So we use these facts to derive umin/umax from smin/smax and vice * versa only if they stay within the same "half". This is equivalent * to checking sign bit: lower half will have sign bit as zero, upper * half have sign bit 1. Below in code we simplify this by just * casting umin/umax as smin/smax and checking if they form valid * range, and vice versa. Those are equivalent checks. */ if ((s64)reg->umin_value <= (s64)reg->umax_value) { reg->smin_value = max_t(s64, reg->smin_value, reg->umin_value); reg->smax_value = min_t(s64, reg->smax_value, reg->umax_value); } /* If we cannot cross the sign boundary, then signed and unsigned bounds * are the same, so combine. This works even in the negative case, e.g. * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff. */ if ((u64)reg->smin_value <= (u64)reg->smax_value) { reg->umin_value = max_t(u64, reg->smin_value, reg->umin_value); reg->umax_value = min_t(u64, reg->smax_value, reg->umax_value); } } static void __reg_deduce_mixed_bounds(struct bpf_reg_state *reg) { /* Try to tighten 64-bit bounds from 32-bit knowledge, using 32-bit * values on both sides of 64-bit range in hope to have tighter range. * E.g., if r1 is [0x1'00000000, 0x3'80000000], and we learn from * 32-bit signed > 0 operation that s32 bounds are now [1; 0x7fffffff]. * With this, we can substitute 1 as low 32-bits of _low_ 64-bit bound * (0x100000000 -> 0x100000001) and 0x7fffffff as low 32-bits of * _high_ 64-bit bound (0x380000000 -> 0x37fffffff) and arrive at a * better overall bounds for r1 as [0x1'000000001; 0x3'7fffffff]. * We just need to make sure that derived bounds we are intersecting * with are well-formed ranges in respective s64 or u64 domain, just * like we do with similar kinds of 32-to-64 or 64-to-32 adjustments. */ __u64 new_umin, new_umax; __s64 new_smin, new_smax; /* u32 -> u64 tightening, it's always well-formed */ new_umin = (reg->umin_value & ~0xffffffffULL) | reg->u32_min_value; new_umax = (reg->umax_value & ~0xffffffffULL) | reg->u32_max_value; reg->umin_value = max_t(u64, reg->umin_value, new_umin); reg->umax_value = min_t(u64, reg->umax_value, new_umax); /* u32 -> s64 tightening, u32 range embedded into s64 preserves range validity */ new_smin = (reg->smin_value & ~0xffffffffULL) | reg->u32_min_value; new_smax = (reg->smax_value & ~0xffffffffULL) | reg->u32_max_value; reg->smin_value = max_t(s64, reg->smin_value, new_smin); reg->smax_value = min_t(s64, reg->smax_value, new_smax); /* if s32 can be treated as valid u32 range, we can use it as well */ if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) { /* s32 -> u64 tightening */ new_umin = (reg->umin_value & ~0xffffffffULL) | (u32)reg->s32_min_value; new_umax = (reg->umax_value & ~0xffffffffULL) | (u32)reg->s32_max_value; reg->umin_value = max_t(u64, reg->umin_value, new_umin); reg->umax_value = min_t(u64, reg->umax_value, new_umax); /* s32 -> s64 tightening */ new_smin = (reg->smin_value & ~0xffffffffULL) | (u32)reg->s32_min_value; new_smax = (reg->smax_value & ~0xffffffffULL) | (u32)reg->s32_max_value; reg->smin_value = max_t(s64, reg->smin_value, new_smin); reg->smax_value = min_t(s64, reg->smax_value, new_smax); } /* Here we would like to handle a special case after sign extending load, * when upper bits for a 64-bit range are all 1s or all 0s. * * Upper bits are all 1s when register is in a range: * [0xffff_ffff_0000_0000, 0xffff_ffff_ffff_ffff] * Upper bits are all 0s when register is in a range: * [0x0000_0000_0000_0000, 0x0000_0000_ffff_ffff] * Together this forms are continuous range: * [0xffff_ffff_0000_0000, 0x0000_0000_ffff_ffff] * * Now, suppose that register range is in fact tighter: * [0xffff_ffff_8000_0000, 0x0000_0000_ffff_ffff] (R) * Also suppose that it's 32-bit range is positive, * meaning that lower 32-bits of the full 64-bit register * are in the range: * [0x0000_0000, 0x7fff_ffff] (W) * * If this happens, then any value in a range: * [0xffff_ffff_0000_0000, 0xffff_ffff_7fff_ffff] * is smaller than a lowest bound of the range (R): * 0xffff_ffff_8000_0000 * which means that upper bits of the full 64-bit register * can't be all 1s, when lower bits are in range (W). * * Note that: * - 0xffff_ffff_8000_0000 == (s64)S32_MIN * - 0x0000_0000_7fff_ffff == (s64)S32_MAX * These relations are used in the conditions below. */ if (reg->s32_min_value >= 0 && reg->smin_value >= S32_MIN && reg->smax_value <= S32_MAX) { reg->smin_value = reg->s32_min_value; reg->smax_value = reg->s32_max_value; reg->umin_value = reg->s32_min_value; reg->umax_value = reg->s32_max_value; reg->var_off = tnum_intersect(reg->var_off, tnum_range(reg->smin_value, reg->smax_value)); } } static void __reg_deduce_bounds(struct bpf_reg_state *reg) { __reg32_deduce_bounds(reg); __reg64_deduce_bounds(reg); __reg_deduce_mixed_bounds(reg); } /* Attempts to improve var_off based on unsigned min/max information */ static void __reg_bound_offset(struct bpf_reg_state *reg) { struct tnum var64_off = tnum_intersect(reg->var_off, tnum_range(reg->umin_value, reg->umax_value)); struct tnum var32_off = tnum_intersect(tnum_subreg(var64_off), tnum_range(reg->u32_min_value, reg->u32_max_value)); reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off); } static void reg_bounds_sync(struct bpf_reg_state *reg) { /* We might have learned new bounds from the var_off. */ __update_reg_bounds(reg); /* We might have learned something about the sign bit. */ __reg_deduce_bounds(reg); __reg_deduce_bounds(reg); /* We might have learned some bits from the bounds. */ __reg_bound_offset(reg); /* Intersecting with the old var_off might have improved our bounds * slightly, e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), * then new var_off is (0; 0x7f...fc) which improves our umax. */ __update_reg_bounds(reg); } static int reg_bounds_sanity_check(struct bpf_verifier_env *env, struct bpf_reg_state *reg, const char *ctx) { const char *msg; if (reg->umin_value > reg->umax_value || reg->smin_value > reg->smax_value || reg->u32_min_value > reg->u32_max_value || reg->s32_min_value > reg->s32_max_value) { msg = "range bounds violation"; goto out; } if (tnum_is_const(reg->var_off)) { u64 uval = reg->var_off.value; s64 sval = (s64)uval; if (reg->umin_value != uval || reg->umax_value != uval || reg->smin_value != sval || reg->smax_value != sval) { msg = "const tnum out of sync with range bounds"; goto out; } } if (tnum_subreg_is_const(reg->var_off)) { u32 uval32 = tnum_subreg(reg->var_off).value; s32 sval32 = (s32)uval32; if (reg->u32_min_value != uval32 || reg->u32_max_value != uval32 || reg->s32_min_value != sval32 || reg->s32_max_value != sval32) { msg = "const subreg tnum out of sync with range bounds"; goto out; } } return 0; out: verbose(env, "REG INVARIANTS VIOLATION (%s): %s u64=[%#llx, %#llx] " "s64=[%#llx, %#llx] u32=[%#x, %#x] s32=[%#x, %#x] var_off=(%#llx, %#llx)\n", ctx, msg, reg->umin_value, reg->umax_value, reg->smin_value, reg->smax_value, reg->u32_min_value, reg->u32_max_value, reg->s32_min_value, reg->s32_max_value, reg->var_off.value, reg->var_off.mask); if (env->test_reg_invariants) return -EFAULT; __mark_reg_unbounded(reg); return 0; } static bool __reg32_bound_s64(s32 a) { return a >= 0 && a <= S32_MAX; } static void __reg_assign_32_into_64(struct bpf_reg_state *reg) { reg->umin_value = reg->u32_min_value; reg->umax_value = reg->u32_max_value; /* Attempt to pull 32-bit signed bounds into 64-bit bounds but must * be positive otherwise set to worse case bounds and refine later * from tnum. */ if (__reg32_bound_s64(reg->s32_min_value) && __reg32_bound_s64(reg->s32_max_value)) { reg->smin_value = reg->s32_min_value; reg->smax_value = reg->s32_max_value; } else { reg->smin_value = 0; reg->smax_value = U32_MAX; } } /* Mark a register as having a completely unknown (scalar) value. */ static void __mark_reg_unknown_imprecise(struct bpf_reg_state *reg) { /* * Clear type, off, and union(map_ptr, range) and * padding between 'type' and union */ memset(reg, 0, offsetof(struct bpf_reg_state, var_off)); reg->type = SCALAR_VALUE; reg->id = 0; reg->ref_obj_id = 0; reg->var_off = tnum_unknown; reg->frameno = 0; reg->precise = false; __mark_reg_unbounded(reg); } /* Mark a register as having a completely unknown (scalar) value, * initialize .precise as true when not bpf capable. */ static void __mark_reg_unknown(const struct bpf_verifier_env *env, struct bpf_reg_state *reg) { __mark_reg_unknown_imprecise(reg); reg->precise = !env->bpf_capable; } static void mark_reg_unknown(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno) { if (WARN_ON(regno >= MAX_BPF_REG)) { verbose(env, "mark_reg_unknown(regs, %u)\n", regno); /* Something bad happened, let's kill all regs except FP */ for (regno = 0; regno < BPF_REG_FP; regno++) __mark_reg_not_init(env, regs + regno); return; } __mark_reg_unknown(env, regs + regno); } static int __mark_reg_s32_range(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno, s32 s32_min, s32 s32_max) { struct bpf_reg_state *reg = regs + regno; reg->s32_min_value = max_t(s32, reg->s32_min_value, s32_min); reg->s32_max_value = min_t(s32, reg->s32_max_value, s32_max); reg->smin_value = max_t(s64, reg->smin_value, s32_min); reg->smax_value = min_t(s64, reg->smax_value, s32_max); reg_bounds_sync(reg); return reg_bounds_sanity_check(env, reg, "s32_range"); } static void __mark_reg_not_init(const struct bpf_verifier_env *env, struct bpf_reg_state *reg) { __mark_reg_unknown(env, reg); reg->type = NOT_INIT; } static void mark_reg_not_init(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno) { if (WARN_ON(regno >= MAX_BPF_REG)) { verbose(env, "mark_reg_not_init(regs, %u)\n", regno); /* Something bad happened, let's kill all regs except FP */ for (regno = 0; regno < BPF_REG_FP; regno++) __mark_reg_not_init(env, regs + regno); return; } __mark_reg_not_init(env, regs + regno); } static void mark_btf_ld_reg(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno, enum bpf_reg_type reg_type, struct btf *btf, u32 btf_id, enum bpf_type_flag flag) { if (reg_type == SCALAR_VALUE) { mark_reg_unknown(env, regs, regno); return; } mark_reg_known_zero(env, regs, regno); regs[regno].type = PTR_TO_BTF_ID | flag; regs[regno].btf = btf; regs[regno].btf_id = btf_id; if (type_may_be_null(flag)) regs[regno].id = ++env->id_gen; } #define DEF_NOT_SUBREG (0) static void init_reg_state(struct bpf_verifier_env *env, struct bpf_func_state *state) { struct bpf_reg_state *regs = state->regs; int i; for (i = 0; i < MAX_BPF_REG; i++) { mark_reg_not_init(env, regs, i); regs[i].live = REG_LIVE_NONE; regs[i].parent = NULL; regs[i].subreg_def = DEF_NOT_SUBREG; } /* frame pointer */ regs[BPF_REG_FP].type = PTR_TO_STACK; mark_reg_known_zero(env, regs, BPF_REG_FP); regs[BPF_REG_FP].frameno = state->frameno; } static struct bpf_retval_range retval_range(s32 minval, s32 maxval) { return (struct bpf_retval_range){ minval, maxval }; } #define BPF_MAIN_FUNC (-1) static void init_func_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int callsite, int frameno, int subprogno) { state->callsite = callsite; state->frameno = frameno; state->subprogno = subprogno; state->callback_ret_range = retval_range(0, 0); init_reg_state(env, state); mark_verifier_state_scratched(env); } /* Similar to push_stack(), but for async callbacks */ static struct bpf_verifier_state *push_async_cb(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx, int subprog, bool is_sleepable) { struct bpf_verifier_stack_elem *elem; struct bpf_func_state *frame; elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); if (!elem) goto err; elem->insn_idx = insn_idx; elem->prev_insn_idx = prev_insn_idx; elem->next = env->head; elem->log_pos = env->log.end_pos; env->head = elem; env->stack_size++; if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) { verbose(env, "The sequence of %d jumps is too complex for async cb.\n", env->stack_size); goto err; } /* Unlike push_stack() do not copy_verifier_state(). * The caller state doesn't matter. * This is async callback. It starts in a fresh stack. * Initialize it similar to do_check_common(). * But we do need to make sure to not clobber insn_hist, so we keep * chaining insn_hist_start/insn_hist_end indices as for a normal * child state. */ elem->st.branches = 1; elem->st.in_sleepable = is_sleepable; elem->st.insn_hist_start = env->cur_state->insn_hist_end; elem->st.insn_hist_end = elem->st.insn_hist_start; frame = kzalloc(sizeof(*frame), GFP_KERNEL); if (!frame) goto err; init_func_state(env, frame, BPF_MAIN_FUNC /* callsite */, 0 /* frameno within this callchain */, subprog /* subprog number within this prog */); elem->st.frame[0] = frame; return &elem->st; err: free_verifier_state(env->cur_state, true); env->cur_state = NULL; /* pop all elements and return */ while (!pop_stack(env, NULL, NULL, false)); return NULL; } enum reg_arg_type { SRC_OP, /* register is used as source operand */ DST_OP, /* register is used as destination operand */ DST_OP_NO_MARK /* same as above, check only, don't mark */ }; static int cmp_subprogs(const void *a, const void *b) { return ((struct bpf_subprog_info *)a)->start - ((struct bpf_subprog_info *)b)->start; } /* Find subprogram that contains instruction at 'off' */ static struct bpf_subprog_info *find_containing_subprog(struct bpf_verifier_env *env, int off) { struct bpf_subprog_info *vals = env->subprog_info; int l, r, m; if (off >= env->prog->len || off < 0 || env->subprog_cnt == 0) return NULL; l = 0; r = env->subprog_cnt - 1; while (l < r) { m = l + (r - l + 1) / 2; if (vals[m].start <= off) l = m; else r = m - 1; } return &vals[l]; } /* Find subprogram that starts exactly at 'off' */ static int find_subprog(struct bpf_verifier_env *env, int off) { struct bpf_subprog_info *p; p = find_containing_subprog(env, off); if (!p || p->start != off) return -ENOENT; return p - env->subprog_info; } static int add_subprog(struct bpf_verifier_env *env, int off) { int insn_cnt = env->prog->len; int ret; if (off >= insn_cnt || off < 0) { verbose(env, "call to invalid destination\n"); return -EINVAL; } ret = find_subprog(env, off); if (ret >= 0) return ret; if (env->subprog_cnt >= BPF_MAX_SUBPROGS) { verbose(env, "too many subprograms\n"); return -E2BIG; } /* determine subprog starts. The end is one before the next starts */ env->subprog_info[env->subprog_cnt++].start = off; sort(env->subprog_info, env->subprog_cnt, sizeof(env->subprog_info[0]), cmp_subprogs, NULL); return env->subprog_cnt - 1; } static int bpf_find_exception_callback_insn_off(struct bpf_verifier_env *env) { struct bpf_prog_aux *aux = env->prog->aux; struct btf *btf = aux->btf; const struct btf_type *t; u32 main_btf_id, id; const char *name; int ret, i; /* Non-zero func_info_cnt implies valid btf */ if (!aux->func_info_cnt) return 0; main_btf_id = aux->func_info[0].type_id; t = btf_type_by_id(btf, main_btf_id); if (!t) { verbose(env, "invalid btf id for main subprog in func_info\n"); return -EINVAL; } name = btf_find_decl_tag_value(btf, t, -1, "exception_callback:"); if (IS_ERR(name)) { ret = PTR_ERR(name); /* If there is no tag present, there is no exception callback */ if (ret == -ENOENT) ret = 0; else if (ret == -EEXIST) verbose(env, "multiple exception callback tags for main subprog\n"); return ret; } ret = btf_find_by_name_kind(btf, name, BTF_KIND_FUNC); if (ret < 0) { verbose(env, "exception callback '%s' could not be found in BTF\n", name); return ret; } id = ret; t = btf_type_by_id(btf, id); if (btf_func_linkage(t) != BTF_FUNC_GLOBAL) { verbose(env, "exception callback '%s' must have global linkage\n", name); return -EINVAL; } ret = 0; for (i = 0; i < aux->func_info_cnt; i++) { if (aux->func_info[i].type_id != id) continue; ret = aux->func_info[i].insn_off; /* Further func_info and subprog checks will also happen * later, so assume this is the right insn_off for now. */ if (!ret) { verbose(env, "invalid exception callback insn_off in func_info: 0\n"); ret = -EINVAL; } } if (!ret) { verbose(env, "exception callback type id not found in func_info\n"); ret = -EINVAL; } return ret; } #define MAX_KFUNC_DESCS 256 #define MAX_KFUNC_BTFS 256 struct bpf_kfunc_desc { struct btf_func_model func_model; u32 func_id; s32 imm; u16 offset; unsigned long addr; }; struct bpf_kfunc_btf { struct btf *btf; struct module *module; u16 offset; }; struct bpf_kfunc_desc_tab { /* Sorted by func_id (BTF ID) and offset (fd_array offset) during * verification. JITs do lookups by bpf_insn, where func_id may not be * available, therefore at the end of verification do_misc_fixups() * sorts this by imm and offset. */ struct bpf_kfunc_desc descs[MAX_KFUNC_DESCS]; u32 nr_descs; }; struct bpf_kfunc_btf_tab { struct bpf_kfunc_btf descs[MAX_KFUNC_BTFS]; u32 nr_descs; }; static int kfunc_desc_cmp_by_id_off(const void *a, const void *b) { const struct bpf_kfunc_desc *d0 = a; const struct bpf_kfunc_desc *d1 = b; /* func_id is not greater than BTF_MAX_TYPE */ return d0->func_id - d1->func_id ?: d0->offset - d1->offset; } static int kfunc_btf_cmp_by_off(const void *a, const void *b) { const struct bpf_kfunc_btf *d0 = a; const struct bpf_kfunc_btf *d1 = b; return d0->offset - d1->offset; } static const struct bpf_kfunc_desc * find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset) { struct bpf_kfunc_desc desc = { .func_id = func_id, .offset = offset, }; struct bpf_kfunc_desc_tab *tab; tab = prog->aux->kfunc_tab; return bsearch(&desc, tab->descs, tab->nr_descs, sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off); } int bpf_get_kfunc_addr(const struct bpf_prog *prog, u32 func_id, u16 btf_fd_idx, u8 **func_addr) { const struct bpf_kfunc_desc *desc; desc = find_kfunc_desc(prog, func_id, btf_fd_idx); if (!desc) return -EFAULT; *func_addr = (u8 *)desc->addr; return 0; } static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env, s16 offset) { struct bpf_kfunc_btf kf_btf = { .offset = offset }; struct bpf_kfunc_btf_tab *tab; struct bpf_kfunc_btf *b; struct module *mod; struct btf *btf; int btf_fd; tab = env->prog->aux->kfunc_btf_tab; b = bsearch(&kf_btf, tab->descs, tab->nr_descs, sizeof(tab->descs[0]), kfunc_btf_cmp_by_off); if (!b) { if (tab->nr_descs == MAX_KFUNC_BTFS) { verbose(env, "too many different module BTFs\n"); return ERR_PTR(-E2BIG); } if (bpfptr_is_null(env->fd_array)) { verbose(env, "kfunc offset > 0 without fd_array is invalid\n"); return ERR_PTR(-EPROTO); } if (copy_from_bpfptr_offset(&btf_fd, env->fd_array, offset * sizeof(btf_fd), sizeof(btf_fd))) return ERR_PTR(-EFAULT); btf = btf_get_by_fd(btf_fd); if (IS_ERR(btf)) { verbose(env, "invalid module BTF fd specified\n"); return btf; } if (!btf_is_module(btf)) { verbose(env, "BTF fd for kfunc is not a module BTF\n"); btf_put(btf); return ERR_PTR(-EINVAL); } mod = btf_try_get_module(btf); if (!mod) { btf_put(btf); return ERR_PTR(-ENXIO); } b = &tab->descs[tab->nr_descs++]; b->btf = btf; b->module = mod; b->offset = offset; /* sort() reorders entries by value, so b may no longer point * to the right entry after this */ sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]), kfunc_btf_cmp_by_off, NULL); } else { btf = b->btf; } return btf; } void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab) { if (!tab) return; while (tab->nr_descs--) { module_put(tab->descs[tab->nr_descs].module); btf_put(tab->descs[tab->nr_descs].btf); } kfree(tab); } static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env, s16 offset) { if (offset) { if (offset < 0) { /* In the future, this can be allowed to increase limit * of fd index into fd_array, interpreted as u16. */ verbose(env, "negative offset disallowed for kernel module function call\n"); return ERR_PTR(-EINVAL); } return __find_kfunc_desc_btf(env, offset); } return btf_vmlinux ?: ERR_PTR(-ENOENT); } static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset) { const struct btf_type *func, *func_proto; struct bpf_kfunc_btf_tab *btf_tab; struct bpf_kfunc_desc_tab *tab; struct bpf_prog_aux *prog_aux; struct bpf_kfunc_desc *desc; const char *func_name; struct btf *desc_btf; unsigned long call_imm; unsigned long addr; int err; prog_aux = env->prog->aux; tab = prog_aux->kfunc_tab; btf_tab = prog_aux->kfunc_btf_tab; if (!tab) { if (!btf_vmlinux) { verbose(env, "calling kernel function is not supported without CONFIG_DEBUG_INFO_BTF\n"); return -ENOTSUPP; } if (!env->prog->jit_requested) { verbose(env, "JIT is required for calling kernel function\n"); return -ENOTSUPP; } if (!bpf_jit_supports_kfunc_call()) { verbose(env, "JIT does not support calling kernel function\n"); return -ENOTSUPP; } if (!env->prog->gpl_compatible) { verbose(env, "cannot call kernel function from non-GPL compatible program\n"); return -EINVAL; } tab = kzalloc(sizeof(*tab), GFP_KERNEL); if (!tab) return -ENOMEM; prog_aux->kfunc_tab = tab; } /* func_id == 0 is always invalid, but instead of returning an error, be * conservative and wait until the code elimination pass before returning * error, so that invalid calls that get pruned out can be in BPF programs * loaded from userspace. It is also required that offset be untouched * for such calls. */ if (!func_id && !offset) return 0; if (!btf_tab && offset) { btf_tab = kzalloc(sizeof(*btf_tab), GFP_KERNEL); if (!btf_tab) return -ENOMEM; prog_aux->kfunc_btf_tab = btf_tab; } desc_btf = find_kfunc_desc_btf(env, offset); if (IS_ERR(desc_btf)) { verbose(env, "failed to find BTF for kernel function\n"); return PTR_ERR(desc_btf); } if (find_kfunc_desc(env->prog, func_id, offset)) return 0; if (tab->nr_descs == MAX_KFUNC_DESCS) { verbose(env, "too many different kernel function calls\n"); return -E2BIG; } func = btf_type_by_id(desc_btf, func_id); if (!func || !btf_type_is_func(func)) { verbose(env, "kernel btf_id %u is not a function\n", func_id); return -EINVAL; } func_proto = btf_type_by_id(desc_btf, func->type); if (!func_proto || !btf_type_is_func_proto(func_proto)) { verbose(env, "kernel function btf_id %u does not have a valid func_proto\n", func_id); return -EINVAL; } func_name = btf_name_by_offset(desc_btf, func->name_off); addr = kallsyms_lookup_name(func_name); if (!addr) { verbose(env, "cannot find address for kernel function %s\n", func_name); return -EINVAL; } specialize_kfunc(env, func_id, offset, &addr); if (bpf_jit_supports_far_kfunc_call()) { call_imm = func_id; } else { call_imm = BPF_CALL_IMM(addr); /* Check whether the relative offset overflows desc->imm */ if ((unsigned long)(s32)call_imm != call_imm) { verbose(env, "address of kernel function %s is out of range\n", func_name); return -EINVAL; } } if (bpf_dev_bound_kfunc_id(func_id)) { err = bpf_dev_bound_kfunc_check(&env->log, prog_aux); if (err) return err; } desc = &tab->descs[tab->nr_descs++]; desc->func_id = func_id; desc->imm = call_imm; desc->offset = offset; desc->addr = addr; err = btf_distill_func_proto(&env->log, desc_btf, func_proto, func_name, &desc->func_model); if (!err) sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off, NULL); return err; } static int kfunc_desc_cmp_by_imm_off(const void *a, const void *b) { const struct bpf_kfunc_desc *d0 = a; const struct bpf_kfunc_desc *d1 = b; if (d0->imm != d1->imm) return d0->imm < d1->imm ? -1 : 1; if (d0->offset != d1->offset) return d0->offset < d1->offset ? -1 : 1; return 0; } static void sort_kfunc_descs_by_imm_off(struct bpf_prog *prog) { struct bpf_kfunc_desc_tab *tab; tab = prog->aux->kfunc_tab; if (!tab) return; sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]), kfunc_desc_cmp_by_imm_off, NULL); } bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog) { return !!prog->aux->kfunc_tab; } const struct btf_func_model * bpf_jit_find_kfunc_model(const struct bpf_prog *prog, const struct bpf_insn *insn) { const struct bpf_kfunc_desc desc = { .imm = insn->imm, .offset = insn->off, }; const struct bpf_kfunc_desc *res; struct bpf_kfunc_desc_tab *tab; tab = prog->aux->kfunc_tab; res = bsearch(&desc, tab->descs, tab->nr_descs, sizeof(tab->descs[0]), kfunc_desc_cmp_by_imm_off); return res ? &res->func_model : NULL; } static int add_subprog_and_kfunc(struct bpf_verifier_env *env) { struct bpf_subprog_info *subprog = env->subprog_info; int i, ret, insn_cnt = env->prog->len, ex_cb_insn; struct bpf_insn *insn = env->prog->insnsi; /* Add entry function. */ ret = add_subprog(env, 0); if (ret) return ret; for (i = 0; i < insn_cnt; i++, insn++) { if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn) && !bpf_pseudo_kfunc_call(insn)) continue; if (!env->bpf_capable) { verbose(env, "loading/calling other bpf or kernel functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n"); return -EPERM; } if (bpf_pseudo_func(insn) || bpf_pseudo_call(insn)) ret = add_subprog(env, i + insn->imm + 1); else ret = add_kfunc_call(env, insn->imm, insn->off); if (ret < 0) return ret; } ret = bpf_find_exception_callback_insn_off(env); if (ret < 0) return ret; ex_cb_insn = ret; /* If ex_cb_insn > 0, this means that the main program has a subprog * marked using BTF decl tag to serve as the exception callback. */ if (ex_cb_insn) { ret = add_subprog(env, ex_cb_insn); if (ret < 0) return ret; for (i = 1; i < env->subprog_cnt; i++) { if (env->subprog_info[i].start != ex_cb_insn) continue; env->exception_callback_subprog = i; mark_subprog_exc_cb(env, i); break; } } /* Add a fake 'exit' subprog which could simplify subprog iteration * logic. 'subprog_cnt' should not be increased. */ subprog[env->subprog_cnt].start = insn_cnt; if (env->log.level & BPF_LOG_LEVEL2) for (i = 0; i < env->subprog_cnt; i++) verbose(env, "func#%d @%d\n", i, subprog[i].start); return 0; } static int check_subprogs(struct bpf_verifier_env *env) { int i, subprog_start, subprog_end, off, cur_subprog = 0; struct bpf_subprog_info *subprog = env->subprog_info; struct bpf_insn *insn = env->prog->insnsi; int insn_cnt = env->prog->len; /* now check that all jumps are within the same subprog */ subprog_start = subprog[cur_subprog].start; subprog_end = subprog[cur_subprog + 1].start; for (i = 0; i < insn_cnt; i++) { u8 code = insn[i].code; if (code == (BPF_JMP | BPF_CALL) && insn[i].src_reg == 0 && insn[i].imm == BPF_FUNC_tail_call) { subprog[cur_subprog].has_tail_call = true; subprog[cur_subprog].tail_call_reachable = true; } if (BPF_CLASS(code) == BPF_LD && (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND)) subprog[cur_subprog].has_ld_abs = true; if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32) goto next; if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL) goto next; if (code == (BPF_JMP32 | BPF_JA)) off = i + insn[i].imm + 1; else off = i + insn[i].off + 1; if (off < subprog_start || off >= subprog_end) { verbose(env, "jump out of range from insn %d to %d\n", i, off); return -EINVAL; } next: if (i == subprog_end - 1) { /* to avoid fall-through from one subprog into another * the last insn of the subprog should be either exit * or unconditional jump back or bpf_throw call */ if (code != (BPF_JMP | BPF_EXIT) && code != (BPF_JMP32 | BPF_JA) && code != (BPF_JMP | BPF_JA)) { verbose(env, "last insn is not an exit or jmp\n"); return -EINVAL; } subprog_start = subprog_end; cur_subprog++; if (cur_subprog < env->subprog_cnt) subprog_end = subprog[cur_subprog + 1].start; } } return 0; } /* Parentage chain of this register (or stack slot) should take care of all * issues like callee-saved registers, stack slot allocation time, etc. */ static int mark_reg_read(struct bpf_verifier_env *env, const struct bpf_reg_state *state, struct bpf_reg_state *parent, u8 flag) { bool writes = parent == state->parent; /* Observe write marks */ int cnt = 0; while (parent) { /* if read wasn't screened by an earlier write ... */ if (writes && state->live & REG_LIVE_WRITTEN) break; if (parent->live & REG_LIVE_DONE) { verbose(env, "verifier BUG type %s var_off %lld off %d\n", reg_type_str(env, parent->type), parent->var_off.value, parent->off); return -EFAULT; } /* The first condition is more likely to be true than the * second, checked it first. */ if ((parent->live & REG_LIVE_READ) == flag || parent->live & REG_LIVE_READ64) /* The parentage chain never changes and * this parent was already marked as LIVE_READ. * There is no need to keep walking the chain again and * keep re-marking all parents as LIVE_READ. * This case happens when the same register is read * multiple times without writes into it in-between. * Also, if parent has the stronger REG_LIVE_READ64 set, * then no need to set the weak REG_LIVE_READ32. */ break; /* ... then we depend on parent's value */ parent->live |= flag; /* REG_LIVE_READ64 overrides REG_LIVE_READ32. */ if (flag == REG_LIVE_READ64) parent->live &= ~REG_LIVE_READ32; state = parent; parent = state->parent; writes = true; cnt++; } if (env->longest_mark_read_walk < cnt) env->longest_mark_read_walk = cnt; return 0; } static int mark_dynptr_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { struct bpf_func_state *state = func(env, reg); int spi, ret; /* For CONST_PTR_TO_DYNPTR, it must have already been done by * check_reg_arg in check_helper_call and mark_btf_func_reg_size in * check_kfunc_call. */ if (reg->type == CONST_PTR_TO_DYNPTR) return 0; spi = dynptr_get_spi(env, reg); if (spi < 0) return spi; /* Caller ensures dynptr is valid and initialized, which means spi is in * bounds and spi is the first dynptr slot. Simply mark stack slot as * read. */ ret = mark_reg_read(env, &state->stack[spi].spilled_ptr, state->stack[spi].spilled_ptr.parent, REG_LIVE_READ64); if (ret) return ret; return mark_reg_read(env, &state->stack[spi - 1].spilled_ptr, state->stack[spi - 1].spilled_ptr.parent, REG_LIVE_READ64); } static int mark_iter_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int spi, int nr_slots) { struct bpf_func_state *state = func(env, reg); int err, i; for (i = 0; i < nr_slots; i++) { struct bpf_reg_state *st = &state->stack[spi - i].spilled_ptr; err = mark_reg_read(env, st, st->parent, REG_LIVE_READ64); if (err) return err; mark_stack_slot_scratched(env, spi - i); } return 0; } /* This function is supposed to be used by the following 32-bit optimization * code only. It returns TRUE if the source or destination register operates * on 64-bit, otherwise return FALSE. */ static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn, u32 regno, struct bpf_reg_state *reg, enum reg_arg_type t) { u8 code, class, op; code = insn->code; class = BPF_CLASS(code); op = BPF_OP(code); if (class == BPF_JMP) { /* BPF_EXIT for "main" will reach here. Return TRUE * conservatively. */ if (op == BPF_EXIT) return true; if (op == BPF_CALL) { /* BPF to BPF call will reach here because of marking * caller saved clobber with DST_OP_NO_MARK for which we * don't care the register def because they are anyway * marked as NOT_INIT already. */ if (insn->src_reg == BPF_PSEUDO_CALL) return false; /* Helper call will reach here because of arg type * check, conservatively return TRUE. */ if (t == SRC_OP) return true; return false; } } if (class == BPF_ALU64 && op == BPF_END && (insn->imm == 16 || insn->imm == 32)) return false; if (class == BPF_ALU64 || class == BPF_JMP || (class == BPF_ALU && op == BPF_END && insn->imm == 64)) return true; if (class == BPF_ALU || class == BPF_JMP32) return false; if (class == BPF_LDX) { if (t != SRC_OP) return BPF_SIZE(code) == BPF_DW || BPF_MODE(code) == BPF_MEMSX; /* LDX source must be ptr. */ return true; } if (class == BPF_STX) { /* BPF_STX (including atomic variants) has multiple source * operands, one of which is a ptr. Check whether the caller is * asking about it. */ if (t == SRC_OP && reg->type != SCALAR_VALUE) return true; return BPF_SIZE(code) == BPF_DW; } if (class == BPF_LD) { u8 mode = BPF_MODE(code); /* LD_IMM64 */ if (mode == BPF_IMM) return true; /* Both LD_IND and LD_ABS return 32-bit data. */ if (t != SRC_OP) return false; /* Implicit ctx ptr. */ if (regno == BPF_REG_6) return true; /* Explicit source could be any width. */ return true; } if (class == BPF_ST) /* The only source register for BPF_ST is a ptr. */ return true; /* Conservatively return true at default. */ return true; } /* Return the regno defined by the insn, or -1. */ static int insn_def_regno(const struct bpf_insn *insn) { switch (BPF_CLASS(insn->code)) { case BPF_JMP: case BPF_JMP32: case BPF_ST: return -1; case BPF_STX: if ((BPF_MODE(insn->code) == BPF_ATOMIC || BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) && (insn->imm & BPF_FETCH)) { if (insn->imm == BPF_CMPXCHG) return BPF_REG_0; else return insn->src_reg; } else { return -1; } default: return insn->dst_reg; } } /* Return TRUE if INSN has defined any 32-bit value explicitly. */ static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn) { int dst_reg = insn_def_regno(insn); if (dst_reg == -1) return false; return !is_reg64(env, insn, dst_reg, NULL, DST_OP); } static void mark_insn_zext(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { s32 def_idx = reg->subreg_def; if (def_idx == DEF_NOT_SUBREG) return; env->insn_aux_data[def_idx - 1].zext_dst = true; /* The dst will be zero extended, so won't be sub-register anymore. */ reg->subreg_def = DEF_NOT_SUBREG; } static int __check_reg_arg(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno, enum reg_arg_type t) { struct bpf_insn *insn = env->prog->insnsi + env->insn_idx; struct bpf_reg_state *reg; bool rw64; if (regno >= MAX_BPF_REG) { verbose(env, "R%d is invalid\n", regno); return -EINVAL; } mark_reg_scratched(env, regno); reg = ®s[regno]; rw64 = is_reg64(env, insn, regno, reg, t); if (t == SRC_OP) { /* check whether register used as source operand can be read */ if (reg->type == NOT_INIT) { verbose(env, "R%d !read_ok\n", regno); return -EACCES; } /* We don't need to worry about FP liveness because it's read-only */ if (regno == BPF_REG_FP) return 0; if (rw64) mark_insn_zext(env, reg); return mark_reg_read(env, reg, reg->parent, rw64 ? REG_LIVE_READ64 : REG_LIVE_READ32); } else { /* check whether register used as dest operand can be written to */ if (regno == BPF_REG_FP) { verbose(env, "frame pointer is read only\n"); return -EACCES; } reg->live |= REG_LIVE_WRITTEN; reg->subreg_def = rw64 ? DEF_NOT_SUBREG : env->insn_idx + 1; if (t == DST_OP) mark_reg_unknown(env, regs, regno); } return 0; } static int check_reg_arg(struct bpf_verifier_env *env, u32 regno, enum reg_arg_type t) { struct bpf_verifier_state *vstate = env->cur_state; struct bpf_func_state *state = vstate->frame[vstate->curframe]; return __check_reg_arg(env, state->regs, regno, t); } static int insn_stack_access_flags(int frameno, int spi) { return INSN_F_STACK_ACCESS | (spi << INSN_F_SPI_SHIFT) | frameno; } static int insn_stack_access_spi(int insn_flags) { return (insn_flags >> INSN_F_SPI_SHIFT) & INSN_F_SPI_MASK; } static int insn_stack_access_frameno(int insn_flags) { return insn_flags & INSN_F_FRAMENO_MASK; } static void mark_jmp_point(struct bpf_verifier_env *env, int idx) { env->insn_aux_data[idx].jmp_point = true; } static bool is_jmp_point(struct bpf_verifier_env *env, int insn_idx) { return env->insn_aux_data[insn_idx].jmp_point; } #define LR_FRAMENO_BITS 3 #define LR_SPI_BITS 6 #define LR_ENTRY_BITS (LR_SPI_BITS + LR_FRAMENO_BITS + 1) #define LR_SIZE_BITS 4 #define LR_FRAMENO_MASK ((1ull << LR_FRAMENO_BITS) - 1) #define LR_SPI_MASK ((1ull << LR_SPI_BITS) - 1) #define LR_SIZE_MASK ((1ull << LR_SIZE_BITS) - 1) #define LR_SPI_OFF LR_FRAMENO_BITS #define LR_IS_REG_OFF (LR_SPI_BITS + LR_FRAMENO_BITS) #define LINKED_REGS_MAX 6 struct linked_reg { u8 frameno; union { u8 spi; u8 regno; }; bool is_reg; }; struct linked_regs { int cnt; struct linked_reg entries[LINKED_REGS_MAX]; }; static struct linked_reg *linked_regs_push(struct linked_regs *s) { if (s->cnt < LINKED_REGS_MAX) return &s->entries[s->cnt++]; return NULL; } /* Use u64 as a vector of 6 10-bit values, use first 4-bits to track * number of elements currently in stack. * Pack one history entry for linked registers as 10 bits in the following format: * - 3-bits frameno * - 6-bits spi_or_reg * - 1-bit is_reg */ static u64 linked_regs_pack(struct linked_regs *s) { u64 val = 0; int i; for (i = 0; i < s->cnt; ++i) { struct linked_reg *e = &s->entries[i]; u64 tmp = 0; tmp |= e->frameno; tmp |= e->spi << LR_SPI_OFF; tmp |= (e->is_reg ? 1 : 0) << LR_IS_REG_OFF; val <<= LR_ENTRY_BITS; val |= tmp; } val <<= LR_SIZE_BITS; val |= s->cnt; return val; } static void linked_regs_unpack(u64 val, struct linked_regs *s) { int i; s->cnt = val & LR_SIZE_MASK; val >>= LR_SIZE_BITS; for (i = 0; i < s->cnt; ++i) { struct linked_reg *e = &s->entries[i]; e->frameno = val & LR_FRAMENO_MASK; e->spi = (val >> LR_SPI_OFF) & LR_SPI_MASK; e->is_reg = (val >> LR_IS_REG_OFF) & 0x1; val >>= LR_ENTRY_BITS; } } /* for any branch, call, exit record the history of jmps in the given state */ static int push_insn_history(struct bpf_verifier_env *env, struct bpf_verifier_state *cur, int insn_flags, u64 linked_regs) { struct bpf_insn_hist_entry *p; size_t alloc_size; /* combine instruction flags if we already recorded this instruction */ if (env->cur_hist_ent) { /* atomic instructions push insn_flags twice, for READ and * WRITE sides, but they should agree on stack slot */ WARN_ONCE((env->cur_hist_ent->flags & insn_flags) && (env->cur_hist_ent->flags & insn_flags) != insn_flags, "verifier insn history bug: insn_idx %d cur flags %x new flags %x\n", env->insn_idx, env->cur_hist_ent->flags, insn_flags); env->cur_hist_ent->flags |= insn_flags; WARN_ONCE(env->cur_hist_ent->linked_regs != 0, "verifier insn history bug: insn_idx %d linked_regs != 0: %#llx\n", env->insn_idx, env->cur_hist_ent->linked_regs); env->cur_hist_ent->linked_regs = linked_regs; return 0; } if (cur->insn_hist_end + 1 > env->insn_hist_cap) { alloc_size = size_mul(cur->insn_hist_end + 1, sizeof(*p)); p = kvrealloc(env->insn_hist, alloc_size, GFP_USER); if (!p) return -ENOMEM; env->insn_hist = p; env->insn_hist_cap = alloc_size / sizeof(*p); } p = &env->insn_hist[cur->insn_hist_end]; p->idx = env->insn_idx; p->prev_idx = env->prev_insn_idx; p->flags = insn_flags; p->linked_regs = linked_regs; cur->insn_hist_end++; env->cur_hist_ent = p; return 0; } static struct bpf_insn_hist_entry *get_insn_hist_entry(struct bpf_verifier_env *env, u32 hist_start, u32 hist_end, int insn_idx) { if (hist_end > hist_start && env->insn_hist[hist_end - 1].idx == insn_idx) return &env->insn_hist[hist_end - 1]; return NULL; } /* Backtrack one insn at a time. If idx is not at the top of recorded * history then previous instruction came from straight line execution. * Return -ENOENT if we exhausted all instructions within given state. * * It's legal to have a bit of a looping with the same starting and ending * insn index within the same state, e.g.: 3->4->5->3, so just because current * instruction index is the same as state's first_idx doesn't mean we are * done. If there is still some jump history left, we should keep going. We * need to take into account that we might have a jump history between given * state's parent and itself, due to checkpointing. In this case, we'll have * history entry recording a jump from last instruction of parent state and * first instruction of given state. */ static int get_prev_insn_idx(const struct bpf_verifier_env *env, struct bpf_verifier_state *st, int insn_idx, u32 hist_start, u32 *hist_endp) { u32 hist_end = *hist_endp; u32 cnt = hist_end - hist_start; if (insn_idx == st->first_insn_idx) { if (cnt == 0) return -ENOENT; if (cnt == 1 && env->insn_hist[hist_start].idx == insn_idx) return -ENOENT; } if (cnt && env->insn_hist[hist_end - 1].idx == insn_idx) { (*hist_endp)--; return env->insn_hist[hist_end - 1].prev_idx; } else { return insn_idx - 1; } } static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn) { const struct btf_type *func; struct btf *desc_btf; if (insn->src_reg != BPF_PSEUDO_KFUNC_CALL) return NULL; desc_btf = find_kfunc_desc_btf(data, insn->off); if (IS_ERR(desc_btf)) return "<error>"; func = btf_type_by_id(desc_btf, insn->imm); return btf_name_by_offset(desc_btf, func->name_off); } static inline void bt_init(struct backtrack_state *bt, u32 frame) { bt->frame = frame; } static inline void bt_reset(struct backtrack_state *bt) { struct bpf_verifier_env *env = bt->env; memset(bt, 0, sizeof(*bt)); bt->env = env; } static inline u32 bt_empty(struct backtrack_state *bt) { u64 mask = 0; int i; for (i = 0; i <= bt->frame; i++) mask |= bt->reg_masks[i] | bt->stack_masks[i]; return mask == 0; } static inline int bt_subprog_enter(struct backtrack_state *bt) { if (bt->frame == MAX_CALL_FRAMES - 1) { verbose(bt->env, "BUG subprog enter from frame %d\n", bt->frame); WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } bt->frame++; return 0; } static inline int bt_subprog_exit(struct backtrack_state *bt) { if (bt->frame == 0) { verbose(bt->env, "BUG subprog exit from frame 0\n"); WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } bt->frame--; return 0; } static inline void bt_set_frame_reg(struct backtrack_state *bt, u32 frame, u32 reg) { bt->reg_masks[frame] |= 1 << reg; } static inline void bt_clear_frame_reg(struct backtrack_state *bt, u32 frame, u32 reg) { bt->reg_masks[frame] &= ~(1 << reg); } static inline void bt_set_reg(struct backtrack_state *bt, u32 reg) { bt_set_frame_reg(bt, bt->frame, reg); } static inline void bt_clear_reg(struct backtrack_state *bt, u32 reg) { bt_clear_frame_reg(bt, bt->frame, reg); } static inline void bt_set_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot) { bt->stack_masks[frame] |= 1ull << slot; } static inline void bt_clear_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot) { bt->stack_masks[frame] &= ~(1ull << slot); } static inline u32 bt_frame_reg_mask(struct backtrack_state *bt, u32 frame) { return bt->reg_masks[frame]; } static inline u32 bt_reg_mask(struct backtrack_state *bt) { return bt->reg_masks[bt->frame]; } static inline u64 bt_frame_stack_mask(struct backtrack_state *bt, u32 frame) { return bt->stack_masks[frame]; } static inline u64 bt_stack_mask(struct backtrack_state *bt) { return bt->stack_masks[bt->frame]; } static inline bool bt_is_reg_set(struct backtrack_state *bt, u32 reg) { return bt->reg_masks[bt->frame] & (1 << reg); } static inline bool bt_is_frame_reg_set(struct backtrack_state *bt, u32 frame, u32 reg) { return bt->reg_masks[frame] & (1 << reg); } static inline bool bt_is_frame_slot_set(struct backtrack_state *bt, u32 frame, u32 slot) { return bt->stack_masks[frame] & (1ull << slot); } /* format registers bitmask, e.g., "r0,r2,r4" for 0x15 mask */ static void fmt_reg_mask(char *buf, ssize_t buf_sz, u32 reg_mask) { DECLARE_BITMAP(mask, 64); bool first = true; int i, n; buf[0] = '\0'; bitmap_from_u64(mask, reg_mask); for_each_set_bit(i, mask, 32) { n = snprintf(buf, buf_sz, "%sr%d", first ? "" : ",", i); first = false; buf += n; buf_sz -= n; if (buf_sz < 0) break; } } /* format stack slots bitmask, e.g., "-8,-24,-40" for 0x15 mask */ static void fmt_stack_mask(char *buf, ssize_t buf_sz, u64 stack_mask) { DECLARE_BITMAP(mask, 64); bool first = true; int i, n; buf[0] = '\0'; bitmap_from_u64(mask, stack_mask); for_each_set_bit(i, mask, 64) { n = snprintf(buf, buf_sz, "%s%d", first ? "" : ",", -(i + 1) * 8); first = false; buf += n; buf_sz -= n; if (buf_sz < 0) break; } } /* If any register R in hist->linked_regs is marked as precise in bt, * do bt_set_frame_{reg,slot}(bt, R) for all registers in hist->linked_regs. */ static void bt_sync_linked_regs(struct backtrack_state *bt, struct bpf_insn_hist_entry *hist) { struct linked_regs linked_regs; bool some_precise = false; int i; if (!hist || hist->linked_regs == 0) return; linked_regs_unpack(hist->linked_regs, &linked_regs); for (i = 0; i < linked_regs.cnt; ++i) { struct linked_reg *e = &linked_regs.entries[i]; if ((e->is_reg && bt_is_frame_reg_set(bt, e->frameno, e->regno)) || (!e->is_reg && bt_is_frame_slot_set(bt, e->frameno, e->spi))) { some_precise = true; break; } } if (!some_precise) return; for (i = 0; i < linked_regs.cnt; ++i) { struct linked_reg *e = &linked_regs.entries[i]; if (e->is_reg) bt_set_frame_reg(bt, e->frameno, e->regno); else bt_set_frame_slot(bt, e->frameno, e->spi); } } static bool calls_callback(struct bpf_verifier_env *env, int insn_idx); /* For given verifier state backtrack_insn() is called from the last insn to * the first insn. Its purpose is to compute a bitmask of registers and * stack slots that needs precision in the parent verifier state. * * @idx is an index of the instruction we are currently processing; * @subseq_idx is an index of the subsequent instruction that: * - *would be* executed next, if jump history is viewed in forward order; * - *was* processed previously during backtracking. */ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx, struct bpf_insn_hist_entry *hist, struct backtrack_state *bt) { const struct bpf_insn_cbs cbs = { .cb_call = disasm_kfunc_name, .cb_print = verbose, .private_data = env, }; struct bpf_insn *insn = env->prog->insnsi + idx; u8 class = BPF_CLASS(insn->code); u8 opcode = BPF_OP(insn->code); u8 mode = BPF_MODE(insn->code); u32 dreg = insn->dst_reg; u32 sreg = insn->src_reg; u32 spi, i, fr; if (insn->code == 0) return 0; if (env->log.level & BPF_LOG_LEVEL2) { fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_reg_mask(bt)); verbose(env, "mark_precise: frame%d: regs=%s ", bt->frame, env->tmp_str_buf); fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_stack_mask(bt)); verbose(env, "stack=%s before ", env->tmp_str_buf); verbose(env, "%d: ", idx); print_bpf_insn(&cbs, insn, env->allow_ptr_leaks); } /* If there is a history record that some registers gained range at this insn, * propagate precision marks to those registers, so that bt_is_reg_set() * accounts for these registers. */ bt_sync_linked_regs(bt, hist); if (class == BPF_ALU || class == BPF_ALU64) { if (!bt_is_reg_set(bt, dreg)) return 0; if (opcode == BPF_END || opcode == BPF_NEG) { /* sreg is reserved and unused * dreg still need precision before this insn */ return 0; } else if (opcode == BPF_MOV) { if (BPF_SRC(insn->code) == BPF_X) { /* dreg = sreg or dreg = (s8, s16, s32)sreg * dreg needs precision after this insn * sreg needs precision before this insn */ bt_clear_reg(bt, dreg); if (sreg != BPF_REG_FP) bt_set_reg(bt, sreg); } else { /* dreg = K * dreg needs precision after this insn. * Corresponding register is already marked * as precise=true in this verifier state. * No further markings in parent are necessary */ bt_clear_reg(bt, dreg); } } else { if (BPF_SRC(insn->code) == BPF_X) { /* dreg += sreg * both dreg and sreg need precision * before this insn */ if (sreg != BPF_REG_FP) bt_set_reg(bt, sreg); } /* else dreg += K * dreg still needs precision before this insn */ } } else if (class == BPF_LDX) { if (!bt_is_reg_set(bt, dreg)) return 0; bt_clear_reg(bt, dreg); /* scalars can only be spilled into stack w/o losing precision. * Load from any other memory can be zero extended. * The desire to keep that precision is already indicated * by 'precise' mark in corresponding register of this state. * No further tracking necessary. */ if (!hist || !(hist->flags & INSN_F_STACK_ACCESS)) return 0; /* dreg = *(u64 *)[fp - off] was a fill from the stack. * that [fp - off] slot contains scalar that needs to be * tracked with precision */ spi = insn_stack_access_spi(hist->flags); fr = insn_stack_access_frameno(hist->flags); bt_set_frame_slot(bt, fr, spi); } else if (class == BPF_STX || class == BPF_ST) { if (bt_is_reg_set(bt, dreg)) /* stx & st shouldn't be using _scalar_ dst_reg * to access memory. It means backtracking * encountered a case of pointer subtraction. */ return -ENOTSUPP; /* scalars can only be spilled into stack */ if (!hist || !(hist->flags & INSN_F_STACK_ACCESS)) return 0; spi = insn_stack_access_spi(hist->flags); fr = insn_stack_access_frameno(hist->flags); if (!bt_is_frame_slot_set(bt, fr, spi)) return 0; bt_clear_frame_slot(bt, fr, spi); if (class == BPF_STX) bt_set_reg(bt, sreg); } else if (class == BPF_JMP || class == BPF_JMP32) { if (bpf_pseudo_call(insn)) { int subprog_insn_idx, subprog; subprog_insn_idx = idx + insn->imm + 1; subprog = find_subprog(env, subprog_insn_idx); if (subprog < 0) return -EFAULT; if (subprog_is_global(env, subprog)) { /* check that jump history doesn't have any * extra instructions from subprog; the next * instruction after call to global subprog * should be literally next instruction in * caller program */ WARN_ONCE(idx + 1 != subseq_idx, "verifier backtracking bug"); /* r1-r5 are invalidated after subprog call, * so for global func call it shouldn't be set * anymore */ if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) { verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } /* global subprog always sets R0 */ bt_clear_reg(bt, BPF_REG_0); return 0; } else { /* static subprog call instruction, which * means that we are exiting current subprog, * so only r1-r5 could be still requested as * precise, r0 and r6-r10 or any stack slot in * the current frame should be zero by now */ if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) { verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } /* we are now tracking register spills correctly, * so any instance of leftover slots is a bug */ if (bt_stack_mask(bt) != 0) { verbose(env, "BUG stack slots %llx\n", bt_stack_mask(bt)); WARN_ONCE(1, "verifier backtracking bug (subprog leftover stack slots)"); return -EFAULT; } /* propagate r1-r5 to the caller */ for (i = BPF_REG_1; i <= BPF_REG_5; i++) { if (bt_is_reg_set(bt, i)) { bt_clear_reg(bt, i); bt_set_frame_reg(bt, bt->frame - 1, i); } } if (bt_subprog_exit(bt)) return -EFAULT; return 0; } } else if (is_sync_callback_calling_insn(insn) && idx != subseq_idx - 1) { /* exit from callback subprog to callback-calling helper or * kfunc call. Use idx/subseq_idx check to discern it from * straight line code backtracking. * Unlike the subprog call handling above, we shouldn't * propagate precision of r1-r5 (if any requested), as they are * not actually arguments passed directly to callback subprogs */ if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) { verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } if (bt_stack_mask(bt) != 0) { verbose(env, "BUG stack slots %llx\n", bt_stack_mask(bt)); WARN_ONCE(1, "verifier backtracking bug (callback leftover stack slots)"); return -EFAULT; } /* clear r1-r5 in callback subprog's mask */ for (i = BPF_REG_1; i <= BPF_REG_5; i++) bt_clear_reg(bt, i); if (bt_subprog_exit(bt)) return -EFAULT; return 0; } else if (opcode == BPF_CALL) { /* kfunc with imm==0 is invalid and fixup_kfunc_call will * catch this error later. Make backtracking conservative * with ENOTSUPP. */ if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL && insn->imm == 0) return -ENOTSUPP; /* regular helper call sets R0 */ bt_clear_reg(bt, BPF_REG_0); if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) { /* if backtracing was looking for registers R1-R5 * they should have been found already. */ verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } } else if (opcode == BPF_EXIT) { bool r0_precise; /* Backtracking to a nested function call, 'idx' is a part of * the inner frame 'subseq_idx' is a part of the outer frame. * In case of a regular function call, instructions giving * precision to registers R1-R5 should have been found already. * In case of a callback, it is ok to have R1-R5 marked for * backtracking, as these registers are set by the function * invoking callback. */ if (subseq_idx >= 0 && calls_callback(env, subseq_idx)) for (i = BPF_REG_1; i <= BPF_REG_5; i++) bt_clear_reg(bt, i); if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) { verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } /* BPF_EXIT in subprog or callback always returns * right after the call instruction, so by checking * whether the instruction at subseq_idx-1 is subprog * call or not we can distinguish actual exit from * *subprog* from exit from *callback*. In the former * case, we need to propagate r0 precision, if * necessary. In the former we never do that. */ r0_precise = subseq_idx - 1 >= 0 && bpf_pseudo_call(&env->prog->insnsi[subseq_idx - 1]) && bt_is_reg_set(bt, BPF_REG_0); bt_clear_reg(bt, BPF_REG_0); if (bt_subprog_enter(bt)) return -EFAULT; if (r0_precise) bt_set_reg(bt, BPF_REG_0); /* r6-r9 and stack slots will stay set in caller frame * bitmasks until we return back from callee(s) */ return 0; } else if (BPF_SRC(insn->code) == BPF_X) { if (!bt_is_reg_set(bt, dreg) && !bt_is_reg_set(bt, sreg)) return 0; /* dreg <cond> sreg * Both dreg and sreg need precision before * this insn. If only sreg was marked precise * before it would be equally necessary to * propagate it to dreg. */ bt_set_reg(bt, dreg); bt_set_reg(bt, sreg); } else if (BPF_SRC(insn->code) == BPF_K) { /* dreg <cond> K * Only dreg still needs precision before * this insn, so for the K-based conditional * there is nothing new to be marked. */ } } else if (class == BPF_LD) { if (!bt_is_reg_set(bt, dreg)) return 0; bt_clear_reg(bt, dreg); /* It's ld_imm64 or ld_abs or ld_ind. * For ld_imm64 no further tracking of precision * into parent is necessary */ if (mode == BPF_IND || mode == BPF_ABS) /* to be analyzed */ return -ENOTSUPP; } /* Propagate precision marks to linked registers, to account for * registers marked as precise in this function. */ bt_sync_linked_regs(bt, hist); return 0; } /* the scalar precision tracking algorithm: * . at the start all registers have precise=false. * . scalar ranges are tracked as normal through alu and jmp insns. * . once precise value of the scalar register is used in: * . ptr + scalar alu * . if (scalar cond K|scalar) * . helper_call(.., scalar, ...) where ARG_CONST is expected * backtrack through the verifier states and mark all registers and * stack slots with spilled constants that these scalar regisers * should be precise. * . during state pruning two registers (or spilled stack slots) * are equivalent if both are not precise. * * Note the verifier cannot simply walk register parentage chain, * since many different registers and stack slots could have been * used to compute single precise scalar. * * The approach of starting with precise=true for all registers and then * backtrack to mark a register as not precise when the verifier detects * that program doesn't care about specific value (e.g., when helper * takes register as ARG_ANYTHING parameter) is not safe. * * It's ok to walk single parentage chain of the verifier states. * It's possible that this backtracking will go all the way till 1st insn. * All other branches will be explored for needing precision later. * * The backtracking needs to deal with cases like: * R8=map_value(id=0,off=0,ks=4,vs=1952,imm=0) R9_w=map_value(id=0,off=40,ks=4,vs=1952,imm=0) * r9 -= r8 * r5 = r9 * if r5 > 0x79f goto pc+7 * R5_w=inv(id=0,umax_value=1951,var_off=(0x0; 0x7ff)) * r5 += 1 * ... * call bpf_perf_event_output#25 * where .arg5_type = ARG_CONST_SIZE_OR_ZERO * * and this case: * r6 = 1 * call foo // uses callee's r6 inside to compute r0 * r0 += r6 * if r0 == 0 goto * * to track above reg_mask/stack_mask needs to be independent for each frame. * * Also if parent's curframe > frame where backtracking started, * the verifier need to mark registers in both frames, otherwise callees * may incorrectly prune callers. This is similar to * commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences") * * For now backtracking falls back into conservative marking. */ static void mark_all_scalars_precise(struct bpf_verifier_env *env, struct bpf_verifier_state *st) { struct bpf_func_state *func; struct bpf_reg_state *reg; int i, j; if (env->log.level & BPF_LOG_LEVEL2) { verbose(env, "mark_precise: frame%d: falling back to forcing all scalars precise\n", st->curframe); } /* big hammer: mark all scalars precise in this path. * pop_stack may still get !precise scalars. * We also skip current state and go straight to first parent state, * because precision markings in current non-checkpointed state are * not needed. See why in the comment in __mark_chain_precision below. */ for (st = st->parent; st; st = st->parent) { for (i = 0; i <= st->curframe; i++) { func = st->frame[i]; for (j = 0; j < BPF_REG_FP; j++) { reg = &func->regs[j]; if (reg->type != SCALAR_VALUE || reg->precise) continue; reg->precise = true; if (env->log.level & BPF_LOG_LEVEL2) { verbose(env, "force_precise: frame%d: forcing r%d to be precise\n", i, j); } } for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) { if (!is_spilled_reg(&func->stack[j])) continue; reg = &func->stack[j].spilled_ptr; if (reg->type != SCALAR_VALUE || reg->precise) continue; reg->precise = true; if (env->log.level & BPF_LOG_LEVEL2) { verbose(env, "force_precise: frame%d: forcing fp%d to be precise\n", i, -(j + 1) * 8); } } } } } static void mark_all_scalars_imprecise(struct bpf_verifier_env *env, struct bpf_verifier_state *st) { struct bpf_func_state *func; struct bpf_reg_state *reg; int i, j; for (i = 0; i <= st->curframe; i++) { func = st->frame[i]; for (j = 0; j < BPF_REG_FP; j++) { reg = &func->regs[j]; if (reg->type != SCALAR_VALUE) continue; reg->precise = false; } for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) { if (!is_spilled_reg(&func->stack[j])) continue; reg = &func->stack[j].spilled_ptr; if (reg->type != SCALAR_VALUE) continue; reg->precise = false; } } } /* * __mark_chain_precision() backtracks BPF program instruction sequence and * chain of verifier states making sure that register *regno* (if regno >= 0) * and/or stack slot *spi* (if spi >= 0) are marked as precisely tracked * SCALARS, as well as any other registers and slots that contribute to * a tracked state of given registers/stack slots, depending on specific BPF * assembly instructions (see backtrack_insns() for exact instruction handling * logic). This backtracking relies on recorded insn_hist and is able to * traverse entire chain of parent states. This process ends only when all the * necessary registers/slots and their transitive dependencies are marked as * precise. * * One important and subtle aspect is that precise marks *do not matter* in * the currently verified state (current state). It is important to understand * why this is the case. * * First, note that current state is the state that is not yet "checkpointed", * i.e., it is not yet put into env->explored_states, and it has no children * states as well. It's ephemeral, and can end up either a) being discarded if * compatible explored state is found at some point or BPF_EXIT instruction is * reached or b) checkpointed and put into env->explored_states, branching out * into one or more children states. * * In the former case, precise markings in current state are completely * ignored by state comparison code (see regsafe() for details). Only * checkpointed ("old") state precise markings are important, and if old * state's register/slot is precise, regsafe() assumes current state's * register/slot as precise and checks value ranges exactly and precisely. If * states turn out to be compatible, current state's necessary precise * markings and any required parent states' precise markings are enforced * after the fact with propagate_precision() logic, after the fact. But it's * important to realize that in this case, even after marking current state * registers/slots as precise, we immediately discard current state. So what * actually matters is any of the precise markings propagated into current * state's parent states, which are always checkpointed (due to b) case above). * As such, for scenario a) it doesn't matter if current state has precise * markings set or not. * * Now, for the scenario b), checkpointing and forking into child(ren) * state(s). Note that before current state gets to checkpointing step, any * processed instruction always assumes precise SCALAR register/slot * knowledge: if precise value or range is useful to prune jump branch, BPF * verifier takes this opportunity enthusiastically. Similarly, when * register's value is used to calculate offset or memory address, exact * knowledge of SCALAR range is assumed, checked, and enforced. So, similar to * what we mentioned above about state comparison ignoring precise markings * during state comparison, BPF verifier ignores and also assumes precise * markings *at will* during instruction verification process. But as verifier * assumes precision, it also propagates any precision dependencies across * parent states, which are not yet finalized, so can be further restricted * based on new knowledge gained from restrictions enforced by their children * states. This is so that once those parent states are finalized, i.e., when * they have no more active children state, state comparison logic in * is_state_visited() would enforce strict and precise SCALAR ranges, if * required for correctness. * * To build a bit more intuition, note also that once a state is checkpointed, * the path we took to get to that state is not important. This is crucial * property for state pruning. When state is checkpointed and finalized at * some instruction index, it can be correctly and safely used to "short * circuit" any *compatible* state that reaches exactly the same instruction * index. I.e., if we jumped to that instruction from a completely different * code path than original finalized state was derived from, it doesn't * matter, current state can be discarded because from that instruction * forward having a compatible state will ensure we will safely reach the * exit. States describe preconditions for further exploration, but completely * forget the history of how we got here. * * This also means that even if we needed precise SCALAR range to get to * finalized state, but from that point forward *that same* SCALAR register is * never used in a precise context (i.e., it's precise value is not needed for * correctness), it's correct and safe to mark such register as "imprecise" * (i.e., precise marking set to false). This is what we rely on when we do * not set precise marking in current state. If no child state requires * precision for any given SCALAR register, it's safe to dictate that it can * be imprecise. If any child state does require this register to be precise, * we'll mark it precise later retroactively during precise markings * propagation from child state to parent states. * * Skipping precise marking setting in current state is a mild version of * relying on the above observation. But we can utilize this property even * more aggressively by proactively forgetting any precise marking in the * current state (which we inherited from the parent state), right before we * checkpoint it and branch off into new child state. This is done by * mark_all_scalars_imprecise() to hopefully get more permissive and generic * finalized states which help in short circuiting more future states. */ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno) { struct backtrack_state *bt = &env->bt; struct bpf_verifier_state *st = env->cur_state; int first_idx = st->first_insn_idx; int last_idx = env->insn_idx; int subseq_idx = -1; struct bpf_func_state *func; struct bpf_reg_state *reg; bool skip_first = true; int i, fr, err; if (!env->bpf_capable) return 0; /* set frame number from which we are starting to backtrack */ bt_init(bt, env->cur_state->curframe); /* Do sanity checks against current state of register and/or stack * slot, but don't set precise flag in current state, as precision * tracking in the current state is unnecessary. */ func = st->frame[bt->frame]; if (regno >= 0) { reg = &func->regs[regno]; if (reg->type != SCALAR_VALUE) { WARN_ONCE(1, "backtracing misuse"); return -EFAULT; } bt_set_reg(bt, regno); } if (bt_empty(bt)) return 0; for (;;) { DECLARE_BITMAP(mask, 64); u32 hist_start = st->insn_hist_start; u32 hist_end = st->insn_hist_end; struct bpf_insn_hist_entry *hist; if (env->log.level & BPF_LOG_LEVEL2) { verbose(env, "mark_precise: frame%d: last_idx %d first_idx %d subseq_idx %d \n", bt->frame, last_idx, first_idx, subseq_idx); } if (last_idx < 0) { /* we are at the entry into subprog, which * is expected for global funcs, but only if * requested precise registers are R1-R5 * (which are global func's input arguments) */ if (st->curframe == 0 && st->frame[0]->subprogno > 0 && st->frame[0]->callsite == BPF_MAIN_FUNC && bt_stack_mask(bt) == 0 && (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) == 0) { bitmap_from_u64(mask, bt_reg_mask(bt)); for_each_set_bit(i, mask, 32) { reg = &st->frame[0]->regs[i]; bt_clear_reg(bt, i); if (reg->type == SCALAR_VALUE) reg->precise = true; } return 0; } verbose(env, "BUG backtracking func entry subprog %d reg_mask %x stack_mask %llx\n", st->frame[0]->subprogno, bt_reg_mask(bt), bt_stack_mask(bt)); WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } for (i = last_idx;;) { if (skip_first) { err = 0; skip_first = false; } else { hist = get_insn_hist_entry(env, hist_start, hist_end, i); err = backtrack_insn(env, i, subseq_idx, hist, bt); } if (err == -ENOTSUPP) { mark_all_scalars_precise(env, env->cur_state); bt_reset(bt); return 0; } else if (err) { return err; } if (bt_empty(bt)) /* Found assignment(s) into tracked register in this state. * Since this state is already marked, just return. * Nothing to be tracked further in the parent state. */ return 0; subseq_idx = i; i = get_prev_insn_idx(env, st, i, hist_start, &hist_end); if (i == -ENOENT) break; if (i >= env->prog->len) { /* This can happen if backtracking reached insn 0 * and there are still reg_mask or stack_mask * to backtrack. * It means the backtracking missed the spot where * particular register was initialized with a constant. */ verbose(env, "BUG backtracking idx %d\n", i); WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } } st = st->parent; if (!st) break; for (fr = bt->frame; fr >= 0; fr--) { func = st->frame[fr]; bitmap_from_u64(mask, bt_frame_reg_mask(bt, fr)); for_each_set_bit(i, mask, 32) { reg = &func->regs[i]; if (reg->type != SCALAR_VALUE) { bt_clear_frame_reg(bt, fr, i); continue; } if (reg->precise) bt_clear_frame_reg(bt, fr, i); else reg->precise = true; } bitmap_from_u64(mask, bt_frame_stack_mask(bt, fr)); for_each_set_bit(i, mask, 64) { if (i >= func->allocated_stack / BPF_REG_SIZE) { verbose(env, "BUG backtracking (stack slot %d, total slots %d)\n", i, func->allocated_stack / BPF_REG_SIZE); WARN_ONCE(1, "verifier backtracking bug (stack slot out of bounds)"); return -EFAULT; } if (!is_spilled_scalar_reg(&func->stack[i])) { bt_clear_frame_slot(bt, fr, i); continue; } reg = &func->stack[i].spilled_ptr; if (reg->precise) bt_clear_frame_slot(bt, fr, i); else reg->precise = true; } if (env->log.level & BPF_LOG_LEVEL2) { fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_frame_reg_mask(bt, fr)); verbose(env, "mark_precise: frame%d: parent state regs=%s ", fr, env->tmp_str_buf); fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_frame_stack_mask(bt, fr)); verbose(env, "stack=%s: ", env->tmp_str_buf); print_verifier_state(env, func, true); } } if (bt_empty(bt)) return 0; subseq_idx = first_idx; last_idx = st->last_insn_idx; first_idx = st->first_insn_idx; } /* if we still have requested precise regs or slots, we missed * something (e.g., stack access through non-r10 register), so * fallback to marking all precise */ if (!bt_empty(bt)) { mark_all_scalars_precise(env, env->cur_state); bt_reset(bt); } return 0; } int mark_chain_precision(struct bpf_verifier_env *env, int regno) { return __mark_chain_precision(env, regno); } /* mark_chain_precision_batch() assumes that env->bt is set in the caller to * desired reg and stack masks across all relevant frames */ static int mark_chain_precision_batch(struct bpf_verifier_env *env) { return __mark_chain_precision(env, -1); } static bool is_spillable_regtype(enum bpf_reg_type type) { switch (base_type(type)) { case PTR_TO_MAP_VALUE: case PTR_TO_STACK: case PTR_TO_CTX: case PTR_TO_PACKET: case PTR_TO_PACKET_META: case PTR_TO_PACKET_END: case PTR_TO_FLOW_KEYS: case CONST_PTR_TO_MAP: case PTR_TO_SOCKET: case PTR_TO_SOCK_COMMON: case PTR_TO_TCP_SOCK: case PTR_TO_XDP_SOCK: case PTR_TO_BTF_ID: case PTR_TO_BUF: case PTR_TO_MEM: case PTR_TO_FUNC: case PTR_TO_MAP_KEY: case PTR_TO_ARENA: return true; default: return false; } } /* Does this register contain a constant zero? */ static bool register_is_null(struct bpf_reg_state *reg) { return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0); } /* check if register is a constant scalar value */ static bool is_reg_const(struct bpf_reg_state *reg, bool subreg32) { return reg->type == SCALAR_VALUE && tnum_is_const(subreg32 ? tnum_subreg(reg->var_off) : reg->var_off); } /* assuming is_reg_const() is true, return constant value of a register */ static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32) { return subreg32 ? tnum_subreg(reg->var_off).value : reg->var_off.value; } static bool __is_pointer_value(bool allow_ptr_leaks, const struct bpf_reg_state *reg) { if (allow_ptr_leaks) return false; return reg->type != SCALAR_VALUE; } static void assign_scalar_id_before_mov(struct bpf_verifier_env *env, struct bpf_reg_state *src_reg) { if (src_reg->type != SCALAR_VALUE) return; if (src_reg->id & BPF_ADD_CONST) { /* * The verifier is processing rX = rY insn and * rY->id has special linked register already. * Cleared it, since multiple rX += const are not supported. */ src_reg->id = 0; src_reg->off = 0; } if (!src_reg->id && !tnum_is_const(src_reg->var_off)) /* Ensure that src_reg has a valid ID that will be copied to * dst_reg and then will be used by sync_linked_regs() to * propagate min/max range. */ src_reg->id = ++env->id_gen; } /* Copy src state preserving dst->parent and dst->live fields */ static void copy_register_state(struct bpf_reg_state *dst, const struct bpf_reg_state *src) { struct bpf_reg_state *parent = dst->parent; enum bpf_reg_liveness live = dst->live; *dst = *src; dst->parent = parent; dst->live = live; } static void save_register_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int spi, struct bpf_reg_state *reg, int size) { int i; copy_register_state(&state->stack[spi].spilled_ptr, reg); if (size == BPF_REG_SIZE) state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; for (i = BPF_REG_SIZE; i > BPF_REG_SIZE - size; i--) state->stack[spi].slot_type[i - 1] = STACK_SPILL; /* size < 8 bytes spill */ for (; i; i--) mark_stack_slot_misc(env, &state->stack[spi].slot_type[i - 1]); } static bool is_bpf_st_mem(struct bpf_insn *insn) { return BPF_CLASS(insn->code) == BPF_ST && BPF_MODE(insn->code) == BPF_MEM; } static int get_reg_width(struct bpf_reg_state *reg) { return fls64(reg->umax_value); } /* See comment for mark_fastcall_pattern_for_call() */ static void check_fastcall_stack_contract(struct bpf_verifier_env *env, struct bpf_func_state *state, int insn_idx, int off) { struct bpf_subprog_info *subprog = &env->subprog_info[state->subprogno]; struct bpf_insn_aux_data *aux = env->insn_aux_data; int i; if (subprog->fastcall_stack_off <= off || aux[insn_idx].fastcall_pattern) return; /* access to the region [max_stack_depth .. fastcall_stack_off) * from something that is not a part of the fastcall pattern, * disable fastcall rewrites for current subprogram by setting * fastcall_stack_off to a value smaller than any possible offset. */ subprog->fastcall_stack_off = S16_MIN; /* reset fastcall aux flags within subprogram, * happens at most once per subprogram */ for (i = subprog->start; i < (subprog + 1)->start; ++i) { aux[i].fastcall_spills_num = 0; aux[i].fastcall_pattern = 0; } } /* check_stack_{read,write}_fixed_off functions track spill/fill of registers, * stack boundary and alignment are checked in check_mem_access() */ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, /* stack frame we're writing to */ struct bpf_func_state *state, int off, int size, int value_regno, int insn_idx) { struct bpf_func_state *cur; /* state of the current function */ int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err; struct bpf_insn *insn = &env->prog->insnsi[insn_idx]; struct bpf_reg_state *reg = NULL; int insn_flags = insn_stack_access_flags(state->frameno, spi); /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, * so it's aligned access and [off, off + size) are within stack limits */ if (!env->allow_ptr_leaks && is_spilled_reg(&state->stack[spi]) && !is_spilled_scalar_reg(&state->stack[spi]) && size != BPF_REG_SIZE) { verbose(env, "attempt to corrupt spilled pointer on stack\n"); return -EACCES; } cur = env->cur_state->frame[env->cur_state->curframe]; if (value_regno >= 0) reg = &cur->regs[value_regno]; if (!env->bypass_spec_v4) { bool sanitize = reg && is_spillable_regtype(reg->type); for (i = 0; i < size; i++) { u8 type = state->stack[spi].slot_type[i]; if (type != STACK_MISC && type != STACK_ZERO) { sanitize = true; break; } } if (sanitize) env->insn_aux_data[insn_idx].sanitize_stack_spill = true; } err = destroy_if_dynptr_stack_slot(env, state, spi); if (err) return err; check_fastcall_stack_contract(env, state, insn_idx, off); mark_stack_slot_scratched(env, spi); if (reg && !(off % BPF_REG_SIZE) && reg->type == SCALAR_VALUE && env->bpf_capable) { bool reg_value_fits; reg_value_fits = get_reg_width(reg) <= BITS_PER_BYTE * size; /* Make sure that reg had an ID to build a relation on spill. */ if (reg_value_fits) assign_scalar_id_before_mov(env, reg); save_register_state(env, state, spi, reg, size); /* Break the relation on a narrowing spill. */ if (!reg_value_fits) state->stack[spi].spilled_ptr.id = 0; } else if (!reg && !(off % BPF_REG_SIZE) && is_bpf_st_mem(insn) && env->bpf_capable) { struct bpf_reg_state *tmp_reg = &env->fake_reg[0]; memset(tmp_reg, 0, sizeof(*tmp_reg)); __mark_reg_known(tmp_reg, insn->imm); tmp_reg->type = SCALAR_VALUE; save_register_state(env, state, spi, tmp_reg, size); } else if (reg && is_spillable_regtype(reg->type)) { /* register containing pointer is being spilled into stack */ if (size != BPF_REG_SIZE) { verbose_linfo(env, insn_idx, "; "); verbose(env, "invalid size of register spill\n"); return -EACCES; } if (state != cur && reg->type == PTR_TO_STACK) { verbose(env, "cannot spill pointers to stack into stack frame of the caller\n"); return -EINVAL; } save_register_state(env, state, spi, reg, size); } else { u8 type = STACK_MISC; /* regular write of data into stack destroys any spilled ptr */ state->stack[spi].spilled_ptr.type = NOT_INIT; /* Mark slots as STACK_MISC if they belonged to spilled ptr/dynptr/iter. */ if (is_stack_slot_special(&state->stack[spi])) for (i = 0; i < BPF_REG_SIZE; i++) scrub_spilled_slot(&state->stack[spi].slot_type[i]); /* only mark the slot as written if all 8 bytes were written * otherwise read propagation may incorrectly stop too soon * when stack slots are partially written. * This heuristic means that read propagation will be * conservative, since it will add reg_live_read marks * to stack slots all the way to first state when programs * writes+reads less than 8 bytes */ if (size == BPF_REG_SIZE) state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; /* when we zero initialize stack slots mark them as such */ if ((reg && register_is_null(reg)) || (!reg && is_bpf_st_mem(insn) && insn->imm == 0)) { /* STACK_ZERO case happened because register spill * wasn't properly aligned at the stack slot boundary, * so it's not a register spill anymore; force * originating register to be precise to make * STACK_ZERO correct for subsequent states */ err = mark_chain_precision(env, value_regno); if (err) return err; type = STACK_ZERO; } /* Mark slots affected by this stack write. */ for (i = 0; i < size; i++) state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] = type; insn_flags = 0; /* not a register spill */ } if (insn_flags) return push_insn_history(env, env->cur_state, insn_flags, 0); return 0; } /* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is * known to contain a variable offset. * This function checks whether the write is permitted and conservatively * tracks the effects of the write, considering that each stack slot in the * dynamic range is potentially written to. * * 'off' includes 'regno->off'. * 'value_regno' can be -1, meaning that an unknown value is being written to * the stack. * * Spilled pointers in range are not marked as written because we don't know * what's going to be actually written. This means that read propagation for * future reads cannot be terminated by this write. * * For privileged programs, uninitialized stack slots are considered * initialized by this write (even though we don't know exactly what offsets * are going to be written to). The idea is that we don't want the verifier to * reject future reads that access slots written to through variable offsets. */ static int check_stack_write_var_off(struct bpf_verifier_env *env, /* func where register points to */ struct bpf_func_state *state, int ptr_regno, int off, int size, int value_regno, int insn_idx) { struct bpf_func_state *cur; /* state of the current function */ int min_off, max_off; int i, err; struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL; struct bpf_insn *insn = &env->prog->insnsi[insn_idx]; bool writing_zero = false; /* set if the fact that we're writing a zero is used to let any * stack slots remain STACK_ZERO */ bool zero_used = false; cur = env->cur_state->frame[env->cur_state->curframe]; ptr_reg = &cur->regs[ptr_regno]; min_off = ptr_reg->smin_value + off; max_off = ptr_reg->smax_value + off + size; if (value_regno >= 0) value_reg = &cur->regs[value_regno]; if ((value_reg && register_is_null(value_reg)) || (!value_reg && is_bpf_st_mem(insn) && insn->imm == 0)) writing_zero = true; for (i = min_off; i < max_off; i++) { int spi; spi = __get_spi(i); err = destroy_if_dynptr_stack_slot(env, state, spi); if (err) return err; } check_fastcall_stack_contract(env, state, insn_idx, min_off); /* Variable offset writes destroy any spilled pointers in range. */ for (i = min_off; i < max_off; i++) { u8 new_type, *stype; int slot, spi; slot = -i - 1; spi = slot / BPF_REG_SIZE; stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE]; mark_stack_slot_scratched(env, spi); if (!env->allow_ptr_leaks && *stype != STACK_MISC && *stype != STACK_ZERO) { /* Reject the write if range we may write to has not * been initialized beforehand. If we didn't reject * here, the ptr status would be erased below (even * though not all slots are actually overwritten), * possibly opening the door to leaks. * * We do however catch STACK_INVALID case below, and * only allow reading possibly uninitialized memory * later for CAP_PERFMON, as the write may not happen to * that slot. */ verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d", insn_idx, i); return -EINVAL; } /* If writing_zero and the spi slot contains a spill of value 0, * maintain the spill type. */ if (writing_zero && *stype == STACK_SPILL && is_spilled_scalar_reg(&state->stack[spi])) { struct bpf_reg_state *spill_reg = &state->stack[spi].spilled_ptr; if (tnum_is_const(spill_reg->var_off) && spill_reg->var_off.value == 0) { zero_used = true; continue; } } /* Erase all other spilled pointers. */ state->stack[spi].spilled_ptr.type = NOT_INIT; /* Update the slot type. */ new_type = STACK_MISC; if (writing_zero && *stype == STACK_ZERO) { new_type = STACK_ZERO; zero_used = true; } /* If the slot is STACK_INVALID, we check whether it's OK to * pretend that it will be initialized by this write. The slot * might not actually be written to, and so if we mark it as * initialized future reads might leak uninitialized memory. * For privileged programs, we will accept such reads to slots * that may or may not be written because, if we're reject * them, the error would be too confusing. */ if (*stype == STACK_INVALID && !env->allow_uninit_stack) { verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d", insn_idx, i); return -EINVAL; } *stype = new_type; } if (zero_used) { /* backtracking doesn't work for STACK_ZERO yet. */ err = mark_chain_precision(env, value_regno); if (err) return err; } return 0; } /* When register 'dst_regno' is assigned some values from stack[min_off, * max_off), we set the register's type according to the types of the * respective stack slots. If all the stack values are known to be zeros, then * so is the destination reg. Otherwise, the register is considered to be * SCALAR. This function does not deal with register filling; the caller must * ensure that all spilled registers in the stack range have been marked as * read. */ static void mark_reg_stack_read(struct bpf_verifier_env *env, /* func where src register points to */ struct bpf_func_state *ptr_state, int min_off, int max_off, int dst_regno) { struct bpf_verifier_state *vstate = env->cur_state; struct bpf_func_state *state = vstate->frame[vstate->curframe]; int i, slot, spi; u8 *stype; int zeros = 0; for (i = min_off; i < max_off; i++) { slot = -i - 1; spi = slot / BPF_REG_SIZE; mark_stack_slot_scratched(env, spi); stype = ptr_state->stack[spi].slot_type; if (stype[slot % BPF_REG_SIZE] != STACK_ZERO) break; zeros++; } if (zeros == max_off - min_off) { /* Any access_size read into register is zero extended, * so the whole register == const_zero. */ __mark_reg_const_zero(env, &state->regs[dst_regno]); } else { /* have read misc data from the stack */ mark_reg_unknown(env, state->regs, dst_regno); } state->regs[dst_regno].live |= REG_LIVE_WRITTEN; } /* Read the stack at 'off' and put the results into the register indicated by * 'dst_regno'. It handles reg filling if the addressed stack slot is a * spilled reg. * * 'dst_regno' can be -1, meaning that the read value is not going to a * register. * * The access is assumed to be within the current stack bounds. */ static int check_stack_read_fixed_off(struct bpf_verifier_env *env, /* func where src register points to */ struct bpf_func_state *reg_state, int off, int size, int dst_regno) { struct bpf_verifier_state *vstate = env->cur_state; struct bpf_func_state *state = vstate->frame[vstate->curframe]; int i, slot = -off - 1, spi = slot / BPF_REG_SIZE; struct bpf_reg_state *reg; u8 *stype, type; int insn_flags = insn_stack_access_flags(reg_state->frameno, spi); stype = reg_state->stack[spi].slot_type; reg = ®_state->stack[spi].spilled_ptr; mark_stack_slot_scratched(env, spi); check_fastcall_stack_contract(env, state, env->insn_idx, off); if (is_spilled_reg(®_state->stack[spi])) { u8 spill_size = 1; for (i = BPF_REG_SIZE - 1; i > 0 && stype[i - 1] == STACK_SPILL; i--) spill_size++; if (size != BPF_REG_SIZE || spill_size != BPF_REG_SIZE) { if (reg->type != SCALAR_VALUE) { verbose_linfo(env, env->insn_idx, "; "); verbose(env, "invalid size of register fill\n"); return -EACCES; } mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); if (dst_regno < 0) return 0; if (size <= spill_size && bpf_stack_narrow_access_ok(off, size, spill_size)) { /* The earlier check_reg_arg() has decided the * subreg_def for this insn. Save it first. */ s32 subreg_def = state->regs[dst_regno].subreg_def; copy_register_state(&state->regs[dst_regno], reg); state->regs[dst_regno].subreg_def = subreg_def; /* Break the relation on a narrowing fill. * coerce_reg_to_size will adjust the boundaries. */ if (get_reg_width(reg) > size * BITS_PER_BYTE) state->regs[dst_regno].id = 0; } else { int spill_cnt = 0, zero_cnt = 0; for (i = 0; i < size; i++) { type = stype[(slot - i) % BPF_REG_SIZE]; if (type == STACK_SPILL) { spill_cnt++; continue; } if (type == STACK_MISC) continue; if (type == STACK_ZERO) { zero_cnt++; continue; } if (type == STACK_INVALID && env->allow_uninit_stack) continue; verbose(env, "invalid read from stack off %d+%d size %d\n", off, i, size); return -EACCES; } if (spill_cnt == size && tnum_is_const(reg->var_off) && reg->var_off.value == 0) { __mark_reg_const_zero(env, &state->regs[dst_regno]); /* this IS register fill, so keep insn_flags */ } else if (zero_cnt == size) { /* similarly to mark_reg_stack_read(), preserve zeroes */ __mark_reg_const_zero(env, &state->regs[dst_regno]); insn_flags = 0; /* not restoring original register state */ } else { mark_reg_unknown(env, state->regs, dst_regno); insn_flags = 0; /* not restoring original register state */ } } state->regs[dst_regno].live |= REG_LIVE_WRITTEN; } else if (dst_regno >= 0) { /* restore register state from stack */ copy_register_state(&state->regs[dst_regno], reg); /* mark reg as written since spilled pointer state likely * has its liveness marks cleared by is_state_visited() * which resets stack/reg liveness for state transitions */ state->regs[dst_regno].live |= REG_LIVE_WRITTEN; } else if (__is_pointer_value(env->allow_ptr_leaks, reg)) { /* If dst_regno==-1, the caller is asking us whether * it is acceptable to use this value as a SCALAR_VALUE * (e.g. for XADD). * We must not allow unprivileged callers to do that * with spilled pointers. */ verbose(env, "leaking pointer from stack off %d\n", off); return -EACCES; } mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); } else { for (i = 0; i < size; i++) { type = stype[(slot - i) % BPF_REG_SIZE]; if (type == STACK_MISC) continue; if (type == STACK_ZERO) continue; if (type == STACK_INVALID && env->allow_uninit_stack) continue; verbose(env, "invalid read from stack off %d+%d size %d\n", off, i, size); return -EACCES; } mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); if (dst_regno >= 0) mark_reg_stack_read(env, reg_state, off, off + size, dst_regno); insn_flags = 0; /* we are not restoring spilled register */ } if (insn_flags) return push_insn_history(env, env->cur_state, insn_flags, 0); return 0; } enum bpf_access_src { ACCESS_DIRECT = 1, /* the access is performed by an instruction */ ACCESS_HELPER = 2, /* the access is performed by a helper */ }; static int check_stack_range_initialized(struct bpf_verifier_env *env, int regno, int off, int access_size, bool zero_size_allowed, enum bpf_access_src type, struct bpf_call_arg_meta *meta); static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno) { return cur_regs(env) + regno; } /* Read the stack at 'ptr_regno + off' and put the result into the register * 'dst_regno'. * 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'), * but not its variable offset. * 'size' is assumed to be <= reg size and the access is assumed to be aligned. * * As opposed to check_stack_read_fixed_off, this function doesn't deal with * filling registers (i.e. reads of spilled register cannot be detected when * the offset is not fixed). We conservatively mark 'dst_regno' as containing * SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable * offset; for a fixed offset check_stack_read_fixed_off should be used * instead. */ static int check_stack_read_var_off(struct bpf_verifier_env *env, int ptr_regno, int off, int size, int dst_regno) { /* The state of the source register. */ struct bpf_reg_state *reg = reg_state(env, ptr_regno); struct bpf_func_state *ptr_state = func(env, reg); int err; int min_off, max_off; /* Note that we pass a NULL meta, so raw access will not be permitted. */ err = check_stack_range_initialized(env, ptr_regno, off, size, false, ACCESS_DIRECT, NULL); if (err) return err; min_off = reg->smin_value + off; max_off = reg->smax_value + off; mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno); check_fastcall_stack_contract(env, ptr_state, env->insn_idx, min_off); return 0; } /* check_stack_read dispatches to check_stack_read_fixed_off or * check_stack_read_var_off. * * The caller must ensure that the offset falls within the allocated stack * bounds. * * 'dst_regno' is a register which will receive the value from the stack. It * can be -1, meaning that the read value is not going to a register. */ static int check_stack_read(struct bpf_verifier_env *env, int ptr_regno, int off, int size, int dst_regno) { struct bpf_reg_state *reg = reg_state(env, ptr_regno); struct bpf_func_state *state = func(env, reg); int err; /* Some accesses are only permitted with a static offset. */ bool var_off = !tnum_is_const(reg->var_off); /* The offset is required to be static when reads don't go to a * register, in order to not leak pointers (see * check_stack_read_fixed_off). */ if (dst_regno < 0 && var_off) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n", tn_buf, off, size); return -EACCES; } /* Variable offset is prohibited for unprivileged mode for simplicity * since it requires corresponding support in Spectre masking for stack * ALU. See also retrieve_ptr_limit(). The check in * check_stack_access_for_ptr_arithmetic() called by * adjust_ptr_min_max_vals() prevents users from creating stack pointers * with variable offsets, therefore no check is required here. Further, * just checking it here would be insufficient as speculative stack * writes could still lead to unsafe speculative behaviour. */ if (!var_off) { off += reg->var_off.value; err = check_stack_read_fixed_off(env, state, off, size, dst_regno); } else { /* Variable offset stack reads need more conservative handling * than fixed offset ones. Note that dst_regno >= 0 on this * branch. */ err = check_stack_read_var_off(env, ptr_regno, off, size, dst_regno); } return err; } /* check_stack_write dispatches to check_stack_write_fixed_off or * check_stack_write_var_off. * * 'ptr_regno' is the register used as a pointer into the stack. * 'off' includes 'ptr_regno->off', but not its variable offset (if any). * 'value_regno' is the register whose value we're writing to the stack. It can * be -1, meaning that we're not writing from a register. * * The caller must ensure that the offset falls within the maximum stack size. */ static int check_stack_write(struct bpf_verifier_env *env, int ptr_regno, int off, int size, int value_regno, int insn_idx) { struct bpf_reg_state *reg = reg_state(env, ptr_regno); struct bpf_func_state *state = func(env, reg); int err; if (tnum_is_const(reg->var_off)) { off += reg->var_off.value; err = check_stack_write_fixed_off(env, state, off, size, value_regno, insn_idx); } else { /* Variable offset stack reads need more conservative handling * than fixed offset ones. */ err = check_stack_write_var_off(env, state, ptr_regno, off, size, value_regno, insn_idx); } return err; } static int check_map_access_type(struct bpf_verifier_env *env, u32 regno, int off, int size, enum bpf_access_type type) { struct bpf_reg_state *regs = cur_regs(env); struct bpf_map *map = regs[regno].map_ptr; u32 cap = bpf_map_flags_to_cap(map); if (type == BPF_WRITE && !(cap & BPF_MAP_CAN_WRITE)) { verbose(env, "write into map forbidden, value_size=%d off=%d size=%d\n", map->value_size, off, size); return -EACCES; } if (type == BPF_READ && !(cap & BPF_MAP_CAN_READ)) { verbose(env, "read from map forbidden, value_size=%d off=%d size=%d\n", map->value_size, off, size); return -EACCES; } return 0; } /* check read/write into memory region (e.g., map value, ringbuf sample, etc) */ static int __check_mem_access(struct bpf_verifier_env *env, int regno, int off, int size, u32 mem_size, bool zero_size_allowed) { bool size_ok = size > 0 || (size == 0 && zero_size_allowed); struct bpf_reg_state *reg; if (off >= 0 && size_ok && (u64)off + size <= mem_size) return 0; reg = &cur_regs(env)[regno]; switch (reg->type) { case PTR_TO_MAP_KEY: verbose(env, "invalid access to map key, key_size=%d off=%d size=%d\n", mem_size, off, size); break; case PTR_TO_MAP_VALUE: verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n", mem_size, off, size); break; case PTR_TO_PACKET: case PTR_TO_PACKET_META: case PTR_TO_PACKET_END: verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", off, size, regno, reg->id, off, mem_size); break; case PTR_TO_MEM: default: verbose(env, "invalid access to memory, mem_size=%u off=%d size=%d\n", mem_size, off, size); } return -EACCES; } /* check read/write into a memory region with possible variable offset */ static int check_mem_region_access(struct bpf_verifier_env *env, u32 regno, int off, int size, u32 mem_size, bool zero_size_allowed) { struct bpf_verifier_state *vstate = env->cur_state; struct bpf_func_state *state = vstate->frame[vstate->curframe]; struct bpf_reg_state *reg = &state->regs[regno]; int err; /* We may have adjusted the register pointing to memory region, so we * need to try adding each of min_value and max_value to off * to make sure our theoretical access will be safe. * * The minimum value is only important with signed * comparisons where we can't assume the floor of a * value is 0. If we are using signed variables for our * index'es we need to make sure that whatever we use * will have a set floor within our range. */ if (reg->smin_value < 0 && (reg->smin_value == S64_MIN || (off + reg->smin_value != (s64)(s32)(off + reg->smin_value)) || reg->smin_value + off < 0)) { verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", regno); return -EACCES; } err = __check_mem_access(env, regno, reg->smin_value + off, size, mem_size, zero_size_allowed); if (err) { verbose(env, "R%d min value is outside of the allowed memory range\n", regno); return err; } /* If we haven't set a max value then we need to bail since we can't be * sure we won't do bad things. * If reg->umax_value + off could overflow, treat that as unbounded too. */ if (reg->umax_value >= BPF_MAX_VAR_OFF) { verbose(env, "R%d unbounded memory access, make sure to bounds check any such access\n", regno); return -EACCES; } err = __check_mem_access(env, regno, reg->umax_value + off, size, mem_size, zero_size_allowed); if (err) { verbose(env, "R%d max value is outside of the allowed memory range\n", regno); return err; } return 0; } static int __check_ptr_off_reg(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno, bool fixed_off_ok) { /* Access to this pointer-typed register or passing it to a helper * is only allowed in its original, unmodified form. */ if (reg->off < 0) { verbose(env, "negative offset %s ptr R%d off=%d disallowed\n", reg_type_str(env, reg->type), regno, reg->off); return -EACCES; } if (!fixed_off_ok && reg->off) { verbose(env, "dereference of modified %s ptr R%d off=%d disallowed\n", reg_type_str(env, reg->type), regno, reg->off); return -EACCES; } if (!tnum_is_const(reg->var_off) || reg->var_off.value) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); verbose(env, "variable %s access var_off=%s disallowed\n", reg_type_str(env, reg->type), tn_buf); return -EACCES; } return 0; } static int check_ptr_off_reg(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno) { return __check_ptr_off_reg(env, reg, regno, false); } static int map_kptr_match_type(struct bpf_verifier_env *env, struct btf_field *kptr_field, struct bpf_reg_state *reg, u32 regno) { const char *targ_name = btf_type_name(kptr_field->kptr.btf, kptr_field->kptr.btf_id); int perm_flags; const char *reg_name = ""; if (btf_is_kernel(reg->btf)) { perm_flags = PTR_MAYBE_NULL | PTR_TRUSTED | MEM_RCU; /* Only unreferenced case accepts untrusted pointers */ if (kptr_field->type == BPF_KPTR_UNREF) perm_flags |= PTR_UNTRUSTED; } else { perm_flags = PTR_MAYBE_NULL | MEM_ALLOC; if (kptr_field->type == BPF_KPTR_PERCPU) perm_flags |= MEM_PERCPU; } if (base_type(reg->type) != PTR_TO_BTF_ID || (type_flag(reg->type) & ~perm_flags)) goto bad_type; /* We need to verify reg->type and reg->btf, before accessing reg->btf */ reg_name = btf_type_name(reg->btf, reg->btf_id); /* For ref_ptr case, release function check should ensure we get one * referenced PTR_TO_BTF_ID, and that its fixed offset is 0. For the * normal store of unreferenced kptr, we must ensure var_off is zero. * Since ref_ptr cannot be accessed directly by BPF insns, checks for * reg->off and reg->ref_obj_id are not needed here. */ if (__check_ptr_off_reg(env, reg, regno, true)) return -EACCES; /* A full type match is needed, as BTF can be vmlinux, module or prog BTF, and * we also need to take into account the reg->off. * * We want to support cases like: * * struct foo { * struct bar br; * struct baz bz; * }; * * struct foo *v; * v = func(); // PTR_TO_BTF_ID * val->foo = v; // reg->off is zero, btf and btf_id match type * val->bar = &v->br; // reg->off is still zero, but we need to retry with * // first member type of struct after comparison fails * val->baz = &v->bz; // reg->off is non-zero, so struct needs to be walked * // to match type * * In the kptr_ref case, check_func_arg_reg_off already ensures reg->off * is zero. We must also ensure that btf_struct_ids_match does not walk * the struct to match type against first member of struct, i.e. reject * second case from above. Hence, when type is BPF_KPTR_REF, we set * strict mode to true for type match. */ if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off, kptr_field->kptr.btf, kptr_field->kptr.btf_id, kptr_field->type != BPF_KPTR_UNREF)) goto bad_type; return 0; bad_type: verbose(env, "invalid kptr access, R%d type=%s%s ", regno, reg_type_str(env, reg->type), reg_name); verbose(env, "expected=%s%s", reg_type_str(env, PTR_TO_BTF_ID), targ_name); if (kptr_field->type == BPF_KPTR_UNREF) verbose(env, " or %s%s\n", reg_type_str(env, PTR_TO_BTF_ID | PTR_UNTRUSTED), targ_name); else verbose(env, "\n"); return -EINVAL; } static bool in_sleepable(struct bpf_verifier_env *env) { return env->prog->sleepable || (env->cur_state && env->cur_state->in_sleepable); } /* The non-sleepable programs and sleepable programs with explicit bpf_rcu_read_lock() * can dereference RCU protected pointers and result is PTR_TRUSTED. */ static bool in_rcu_cs(struct bpf_verifier_env *env) { return env->cur_state->active_rcu_lock || cur_func(env)->active_locks || !in_sleepable(env); } /* Once GCC supports btf_type_tag the following mechanism will be replaced with tag check */ BTF_SET_START(rcu_protected_types) BTF_ID(struct, prog_test_ref_kfunc) #ifdef CONFIG_CGROUPS BTF_ID(struct, cgroup) #endif #ifdef CONFIG_BPF_JIT BTF_ID(struct, bpf_cpumask) #endif BTF_ID(struct, task_struct) BTF_ID(struct, bpf_crypto_ctx) BTF_SET_END(rcu_protected_types) static bool rcu_protected_object(const struct btf *btf, u32 btf_id) { if (!btf_is_kernel(btf)) return true; return btf_id_set_contains(&rcu_protected_types, btf_id); } static struct btf_record *kptr_pointee_btf_record(struct btf_field *kptr_field) { struct btf_struct_meta *meta; if (btf_is_kernel(kptr_field->kptr.btf)) return NULL; meta = btf_find_struct_meta(kptr_field->kptr.btf, kptr_field->kptr.btf_id); return meta ? meta->record : NULL; } static bool rcu_safe_kptr(const struct btf_field *field) { const struct btf_field_kptr *kptr = &field->kptr; return field->type == BPF_KPTR_PERCPU || (field->type == BPF_KPTR_REF && rcu_protected_object(kptr->btf, kptr->btf_id)); } static u32 btf_ld_kptr_type(struct bpf_verifier_env *env, struct btf_field *kptr_field) { struct btf_record *rec; u32 ret; ret = PTR_MAYBE_NULL; if (rcu_safe_kptr(kptr_field) && in_rcu_cs(env)) { ret |= MEM_RCU; if (kptr_field->type == BPF_KPTR_PERCPU) ret |= MEM_PERCPU; else if (!btf_is_kernel(kptr_field->kptr.btf)) ret |= MEM_ALLOC; rec = kptr_pointee_btf_record(kptr_field); if (rec && btf_record_has_field(rec, BPF_GRAPH_NODE)) ret |= NON_OWN_REF; } else { ret |= PTR_UNTRUSTED; } return ret; } static int mark_uptr_ld_reg(struct bpf_verifier_env *env, u32 regno, struct btf_field *field) { struct bpf_reg_state *reg; const struct btf_type *t; t = btf_type_by_id(field->kptr.btf, field->kptr.btf_id); mark_reg_known_zero(env, cur_regs(env), regno); reg = reg_state(env, regno); reg->type = PTR_TO_MEM | PTR_MAYBE_NULL; reg->mem_size = t->size; reg->id = ++env->id_gen; return 0; } static int check_map_kptr_access(struct bpf_verifier_env *env, u32 regno, int value_regno, int insn_idx, struct btf_field *kptr_field) { struct bpf_insn *insn = &env->prog->insnsi[insn_idx]; int class = BPF_CLASS(insn->code); struct bpf_reg_state *val_reg; /* Things we already checked for in check_map_access and caller: * - Reject cases where variable offset may touch kptr * - size of access (must be BPF_DW) * - tnum_is_const(reg->var_off) * - kptr_field->offset == off + reg->var_off.value */ /* Only BPF_[LDX,STX,ST] | BPF_MEM | BPF_DW is supported */ if (BPF_MODE(insn->code) != BPF_MEM) { verbose(env, "kptr in map can only be accessed using BPF_MEM instruction mode\n"); return -EACCES; } /* We only allow loading referenced kptr, since it will be marked as * untrusted, similar to unreferenced kptr. */ if (class != BPF_LDX && (kptr_field->type == BPF_KPTR_REF || kptr_field->type == BPF_KPTR_PERCPU)) { verbose(env, "store to referenced kptr disallowed\n"); return -EACCES; } if (class != BPF_LDX && kptr_field->type == BPF_UPTR) { verbose(env, "store to uptr disallowed\n"); return -EACCES; } if (class == BPF_LDX) { if (kptr_field->type == BPF_UPTR) return mark_uptr_ld_reg(env, value_regno, kptr_field); /* We can simply mark the value_regno receiving the pointer * value from map as PTR_TO_BTF_ID, with the correct type. */ mark_btf_ld_reg(env, cur_regs(env), value_regno, PTR_TO_BTF_ID, kptr_field->kptr.btf, kptr_field->kptr.btf_id, btf_ld_kptr_type(env, kptr_field)); } else if (class == BPF_STX) { val_reg = reg_state(env, value_regno); if (!register_is_null(val_reg) && map_kptr_match_type(env, kptr_field, val_reg, value_regno)) return -EACCES; } else if (class == BPF_ST) { if (insn->imm) { verbose(env, "BPF_ST imm must be 0 when storing to kptr at off=%u\n", kptr_field->offset); return -EACCES; } } else { verbose(env, "kptr in map can only be accessed using BPF_LDX/BPF_STX/BPF_ST\n"); return -EACCES; } return 0; } /* check read/write into a map element with possible variable offset */ static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off, int size, bool zero_size_allowed, enum bpf_access_src src) { struct bpf_verifier_state *vstate = env->cur_state; struct bpf_func_state *state = vstate->frame[vstate->curframe]; struct bpf_reg_state *reg = &state->regs[regno]; struct bpf_map *map = reg->map_ptr; struct btf_record *rec; int err, i; err = check_mem_region_access(env, regno, off, size, map->value_size, zero_size_allowed); if (err) return err; if (IS_ERR_OR_NULL(map->record)) return 0; rec = map->record; for (i = 0; i < rec->cnt; i++) { struct btf_field *field = &rec->fields[i]; u32 p = field->offset; /* If any part of a field can be touched by load/store, reject * this program. To check that [x1, x2) overlaps with [y1, y2), * it is sufficient to check x1 < y2 && y1 < x2. */ if (reg->smin_value + off < p + field->size && p < reg->umax_value + off + size) { switch (field->type) { case BPF_KPTR_UNREF: case BPF_KPTR_REF: case BPF_KPTR_PERCPU: case BPF_UPTR: if (src != ACCESS_DIRECT) { verbose(env, "%s cannot be accessed indirectly by helper\n", btf_field_type_name(field->type)); return -EACCES; } if (!tnum_is_const(reg->var_off)) { verbose(env, "%s access cannot have variable offset\n", btf_field_type_name(field->type)); return -EACCES; } if (p != off + reg->var_off.value) { verbose(env, "%s access misaligned expected=%u off=%llu\n", btf_field_type_name(field->type), p, off + reg->var_off.value); return -EACCES; } if (size != bpf_size_to_bytes(BPF_DW)) { verbose(env, "%s access size must be BPF_DW\n", btf_field_type_name(field->type)); return -EACCES; } break; default: verbose(env, "%s cannot be accessed directly by load/store\n", btf_field_type_name(field->type)); return -EACCES; } } } return 0; } #define MAX_PACKET_OFF 0xffff static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, const struct bpf_call_arg_meta *meta, enum bpf_access_type t) { enum bpf_prog_type prog_type = resolve_prog_type(env->prog); switch (prog_type) { /* Program types only with direct read access go here! */ case BPF_PROG_TYPE_LWT_IN: case BPF_PROG_TYPE_LWT_OUT: case BPF_PROG_TYPE_LWT_SEG6LOCAL: case BPF_PROG_TYPE_SK_REUSEPORT: case BPF_PROG_TYPE_FLOW_DISSECTOR: case BPF_PROG_TYPE_CGROUP_SKB: if (t == BPF_WRITE) return false; fallthrough; /* Program types with direct read + write access go here! */ case BPF_PROG_TYPE_SCHED_CLS: case BPF_PROG_TYPE_SCHED_ACT: case BPF_PROG_TYPE_XDP: case BPF_PROG_TYPE_LWT_XMIT: case BPF_PROG_TYPE_SK_SKB: case BPF_PROG_TYPE_SK_MSG: if (meta) return meta->pkt_access; env->seen_direct_write = true; return true; case BPF_PROG_TYPE_CGROUP_SOCKOPT: if (t == BPF_WRITE) env->seen_direct_write = true; return true; default: return false; } } static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, int size, bool zero_size_allowed) { struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *reg = ®s[regno]; int err; /* We may have added a variable offset to the packet pointer; but any * reg->range we have comes after that. We are only checking the fixed * offset. */ /* We don't allow negative numbers, because we aren't tracking enough * detail to prove they're safe. */ if (reg->smin_value < 0) { verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", regno); return -EACCES; } err = reg->range < 0 ? -EINVAL : __check_mem_access(env, regno, off, size, reg->range, zero_size_allowed); if (err) { verbose(env, "R%d offset is outside of the packet\n", regno); return err; } /* __check_mem_access has made sure "off + size - 1" is within u16. * reg->umax_value can't be bigger than MAX_PACKET_OFF which is 0xffff, * otherwise find_good_pkt_pointers would have refused to set range info * that __check_mem_access would have rejected this pkt access. * Therefore, "off + reg->umax_value + size - 1" won't overflow u32. */ env->prog->aux->max_pkt_offset = max_t(u32, env->prog->aux->max_pkt_offset, off + reg->umax_value + size - 1); return err; } /* check access to 'struct bpf_context' fields. Supports fixed offsets only */ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, enum bpf_access_type t, enum bpf_reg_type *reg_type, struct btf **btf, u32 *btf_id, bool *is_retval, bool is_ldsx) { struct bpf_insn_access_aux info = { .reg_type = *reg_type, .log = &env->log, .is_retval = false, .is_ldsx = is_ldsx, }; if (env->ops->is_valid_access && env->ops->is_valid_access(off, size, t, env->prog, &info)) { /* A non zero info.ctx_field_size indicates that this field is a * candidate for later verifier transformation to load the whole * field and then apply a mask when accessed with a narrower * access than actual ctx access size. A zero info.ctx_field_size * will only allow for whole field access and rejects any other * type of narrower access. */ *reg_type = info.reg_type; *is_retval = info.is_retval; if (base_type(*reg_type) == PTR_TO_BTF_ID) { *btf = info.btf; *btf_id = info.btf_id; } else { env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; } /* remember the offset of last byte accessed in ctx */ if (env->prog->aux->max_ctx_offset < off + size) env->prog->aux->max_ctx_offset = off + size; return 0; } verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size); return -EACCES; } static int check_flow_keys_access(struct bpf_verifier_env *env, int off, int size) { if (size < 0 || off < 0 || (u64)off + size > sizeof(struct bpf_flow_keys)) { verbose(env, "invalid access to flow keys off=%d size=%d\n", off, size); return -EACCES; } return 0; } static int check_sock_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off, int size, enum bpf_access_type t) { struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *reg = ®s[regno]; struct bpf_insn_access_aux info = {}; bool valid; if (reg->smin_value < 0) { verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", regno); return -EACCES; } switch (reg->type) { case PTR_TO_SOCK_COMMON: valid = bpf_sock_common_is_valid_access(off, size, t, &info); break; case PTR_TO_SOCKET: valid = bpf_sock_is_valid_access(off, size, t, &info); break; case PTR_TO_TCP_SOCK: valid = bpf_tcp_sock_is_valid_access(off, size, t, &info); break; case PTR_TO_XDP_SOCK: valid = bpf_xdp_sock_is_valid_access(off, size, t, &info); break; default: valid = false; } if (valid) { env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; return 0; } verbose(env, "R%d invalid %s access off=%d size=%d\n", regno, reg_type_str(env, reg->type), off, size); return -EACCES; } static bool is_pointer_value(struct bpf_verifier_env *env, int regno) { return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno)); } static bool is_ctx_reg(struct bpf_verifier_env *env, int regno) { const struct bpf_reg_state *reg = reg_state(env, regno); return reg->type == PTR_TO_CTX; } static bool is_sk_reg(struct bpf_verifier_env *env, int regno) { const struct bpf_reg_state *reg = reg_state(env, regno); return type_is_sk_pointer(reg->type); } static bool is_pkt_reg(struct bpf_verifier_env *env, int regno) { const struct bpf_reg_state *reg = reg_state(env, regno); return type_is_pkt_pointer(reg->type); } static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno) { const struct bpf_reg_state *reg = reg_state(env, regno); /* Separate to is_ctx_reg() since we still want to allow BPF_ST here. */ return reg->type == PTR_TO_FLOW_KEYS; } static bool is_arena_reg(struct bpf_verifier_env *env, int regno) { const struct bpf_reg_state *reg = reg_state(env, regno); return reg->type == PTR_TO_ARENA; } static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = { #ifdef CONFIG_NET [PTR_TO_SOCKET] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK], [PTR_TO_SOCK_COMMON] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON], [PTR_TO_TCP_SOCK] = &btf_sock_ids[BTF_SOCK_TYPE_TCP], #endif [CONST_PTR_TO_MAP] = btf_bpf_map_id, }; static bool is_trusted_reg(const struct bpf_reg_state *reg) { /* A referenced register is always trusted. */ if (reg->ref_obj_id) return true; /* Types listed in the reg2btf_ids are always trusted */ if (reg2btf_ids[base_type(reg->type)] && !bpf_type_has_unsafe_modifiers(reg->type)) return true; /* If a register is not referenced, it is trusted if it has the * MEM_ALLOC or PTR_TRUSTED type modifiers, and no others. Some of the * other type modifiers may be safe, but we elect to take an opt-in * approach here as some (e.g. PTR_UNTRUSTED and PTR_MAYBE_NULL) are * not. * * Eventually, we should make PTR_TRUSTED the single source of truth * for whether a register is trusted. */ return type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS && !bpf_type_has_unsafe_modifiers(reg->type); } static bool is_rcu_reg(const struct bpf_reg_state *reg) { return reg->type & MEM_RCU; } static void clear_trusted_flags(enum bpf_type_flag *flag) { *flag &= ~(BPF_REG_TRUSTED_MODIFIERS | MEM_RCU); } static int check_pkt_ptr_alignment(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int off, int size, bool strict) { struct tnum reg_off; int ip_align; /* Byte size accesses are always allowed. */ if (!strict || size == 1) return 0; /* For platforms that do not have a Kconfig enabling * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of * NET_IP_ALIGN is universally set to '2'. And on platforms * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get * to this code only in strict mode where we want to emulate * the NET_IP_ALIGN==2 checking. Therefore use an * unconditional IP align value of '2'. */ ip_align = 2; reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off)); if (!tnum_is_aligned(reg_off, size)) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); verbose(env, "misaligned packet access off %d+%s+%d+%d size %d\n", ip_align, tn_buf, reg->off, off, size); return -EACCES; } return 0; } static int check_generic_ptr_alignment(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, const char *pointer_desc, int off, int size, bool strict) { struct tnum reg_off; /* Byte size accesses are always allowed. */ if (!strict || size == 1) return 0; reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off)); if (!tnum_is_aligned(reg_off, size)) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); verbose(env, "misaligned %saccess off %s+%d+%d size %d\n", pointer_desc, tn_buf, reg->off, off, size); return -EACCES; } return 0; } static int check_ptr_alignment(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int off, int size, bool strict_alignment_once) { bool strict = env->strict_alignment || strict_alignment_once; const char *pointer_desc = ""; switch (reg->type) { case PTR_TO_PACKET: case PTR_TO_PACKET_META: /* Special case, because of NET_IP_ALIGN. Given metadata sits * right in front, treat it the very same way. */ return check_pkt_ptr_alignment(env, reg, off, size, strict); case PTR_TO_FLOW_KEYS: pointer_desc = "flow keys "; break; case PTR_TO_MAP_KEY: pointer_desc = "key "; break; case PTR_TO_MAP_VALUE: pointer_desc = "value "; break; case PTR_TO_CTX: pointer_desc = "context "; break; case PTR_TO_STACK: pointer_desc = "stack "; /* The stack spill tracking logic in check_stack_write_fixed_off() * and check_stack_read_fixed_off() relies on stack accesses being * aligned. */ strict = true; break; case PTR_TO_SOCKET: pointer_desc = "sock "; break; case PTR_TO_SOCK_COMMON: pointer_desc = "sock_common "; break; case PTR_TO_TCP_SOCK: pointer_desc = "tcp_sock "; break; case PTR_TO_XDP_SOCK: pointer_desc = "xdp_sock "; break; case PTR_TO_ARENA: return 0; default: break; } return check_generic_ptr_alignment(env, reg, pointer_desc, off, size, strict); } static enum priv_stack_mode bpf_enable_priv_stack(struct bpf_prog *prog) { if (!bpf_jit_supports_private_stack()) return NO_PRIV_STACK; /* bpf_prog_check_recur() checks all prog types that use bpf trampoline * while kprobe/tp/perf_event/raw_tp don't use trampoline hence checked * explicitly. */ switch (prog->type) { case BPF_PROG_TYPE_KPROBE: case BPF_PROG_TYPE_TRACEPOINT: case BPF_PROG_TYPE_PERF_EVENT: case BPF_PROG_TYPE_RAW_TRACEPOINT: return PRIV_STACK_ADAPTIVE; case BPF_PROG_TYPE_TRACING: case BPF_PROG_TYPE_LSM: case BPF_PROG_TYPE_STRUCT_OPS: if (prog->aux->priv_stack_requested || bpf_prog_check_recur(prog)) return PRIV_STACK_ADAPTIVE; fallthrough; default: break; } return NO_PRIV_STACK; } static int round_up_stack_depth(struct bpf_verifier_env *env, int stack_depth) { if (env->prog->jit_requested) return round_up(stack_depth, 16); /* round up to 32-bytes, since this is granularity * of interpreter stack size */ return round_up(max_t(u32, stack_depth, 1), 32); } /* starting from main bpf function walk all instructions of the function * and recursively walk all callees that given function can call. * Ignore jump and exit insns. * Since recursion is prevented by check_cfg() this algorithm * only needs a local stack of MAX_CALL_FRAMES to remember callsites */ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx, bool priv_stack_supported) { struct bpf_subprog_info *subprog = env->subprog_info; struct bpf_insn *insn = env->prog->insnsi; int depth = 0, frame = 0, i, subprog_end, subprog_depth; bool tail_call_reachable = false; int ret_insn[MAX_CALL_FRAMES]; int ret_prog[MAX_CALL_FRAMES]; int j; i = subprog[idx].start; if (!priv_stack_supported) subprog[idx].priv_stack_mode = NO_PRIV_STACK; process_func: /* protect against potential stack overflow that might happen when * bpf2bpf calls get combined with tailcalls. Limit the caller's stack * depth for such case down to 256 so that the worst case scenario * would result in 8k stack size (32 which is tailcall limit * 256 = * 8k). * * To get the idea what might happen, see an example: * func1 -> sub rsp, 128 * subfunc1 -> sub rsp, 256 * tailcall1 -> add rsp, 256 * func2 -> sub rsp, 192 (total stack size = 128 + 192 = 320) * subfunc2 -> sub rsp, 64 * subfunc22 -> sub rsp, 128 * tailcall2 -> add rsp, 128 * func3 -> sub rsp, 32 (total stack size 128 + 192 + 64 + 32 = 416) * * tailcall will unwind the current stack frame but it will not get rid * of caller's stack as shown on the example above. */ if (idx && subprog[idx].has_tail_call && depth >= 256) { verbose(env, "tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n", depth); return -EACCES; } subprog_depth = round_up_stack_depth(env, subprog[idx].stack_depth); if (priv_stack_supported) { /* Request private stack support only if the subprog stack * depth is no less than BPF_PRIV_STACK_MIN_SIZE. This is to * avoid jit penalty if the stack usage is small. */ if (subprog[idx].priv_stack_mode == PRIV_STACK_UNKNOWN && subprog_depth >= BPF_PRIV_STACK_MIN_SIZE) subprog[idx].priv_stack_mode = PRIV_STACK_ADAPTIVE; } if (subprog[idx].priv_stack_mode == PRIV_STACK_ADAPTIVE) { if (subprog_depth > MAX_BPF_STACK) { verbose(env, "stack size of subprog %d is %d. Too large\n", idx, subprog_depth); return -EACCES; } } else { depth += subprog_depth; if (depth > MAX_BPF_STACK) { verbose(env, "combined stack size of %d calls is %d. Too large\n", frame + 1, depth); return -EACCES; } } continue_func: subprog_end = subprog[idx + 1].start; for (; i < subprog_end; i++) { int next_insn, sidx; if (bpf_pseudo_kfunc_call(insn + i) && !insn[i].off) { bool err = false; if (!is_bpf_throw_kfunc(insn + i)) continue; if (subprog[idx].is_cb) err = true; for (int c = 0; c < frame && !err; c++) { if (subprog[ret_prog[c]].is_cb) { err = true; break; } } if (!err) continue; verbose(env, "bpf_throw kfunc (insn %d) cannot be called from callback subprog %d\n", i, idx); return -EINVAL; } if (!bpf_pseudo_call(insn + i) && !bpf_pseudo_func(insn + i)) continue; /* remember insn and function to return to */ ret_insn[frame] = i + 1; ret_prog[frame] = idx; /* find the callee */ next_insn = i + insn[i].imm + 1; sidx = find_subprog(env, next_insn); if (sidx < 0) { WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", next_insn); return -EFAULT; } if (subprog[sidx].is_async_cb) { if (subprog[sidx].has_tail_call) { verbose(env, "verifier bug. subprog has tail_call and async cb\n"); return -EFAULT; } /* async callbacks don't increase bpf prog stack size unless called directly */ if (!bpf_pseudo_call(insn + i)) continue; if (subprog[sidx].is_exception_cb) { verbose(env, "insn %d cannot call exception cb directly\n", i); return -EINVAL; } } i = next_insn; idx = sidx; if (!priv_stack_supported) subprog[idx].priv_stack_mode = NO_PRIV_STACK; if (subprog[idx].has_tail_call) tail_call_reachable = true; frame++; if (frame >= MAX_CALL_FRAMES) { verbose(env, "the call stack of %d frames is too deep !\n", frame); return -E2BIG; } goto process_func; } /* if tail call got detected across bpf2bpf calls then mark each of the * currently present subprog frames as tail call reachable subprogs; * this info will be utilized by JIT so that we will be preserving the * tail call counter throughout bpf2bpf calls combined with tailcalls */ if (tail_call_reachable) for (j = 0; j < frame; j++) { if (subprog[ret_prog[j]].is_exception_cb) { verbose(env, "cannot tail call within exception cb\n"); return -EINVAL; } subprog[ret_prog[j]].tail_call_reachable = true; } if (subprog[0].tail_call_reachable) env->prog->aux->tail_call_reachable = true; /* end of for() loop means the last insn of the 'subprog' * was reached. Doesn't matter whether it was JA or EXIT */ if (frame == 0) return 0; if (subprog[idx].priv_stack_mode != PRIV_STACK_ADAPTIVE) depth -= round_up_stack_depth(env, subprog[idx].stack_depth); frame--; i = ret_insn[frame]; idx = ret_prog[frame]; goto continue_func; } static int check_max_stack_depth(struct bpf_verifier_env *env) { enum priv_stack_mode priv_stack_mode = PRIV_STACK_UNKNOWN; struct bpf_subprog_info *si = env->subprog_info; bool priv_stack_supported; int ret; for (int i = 0; i < env->subprog_cnt; i++) { if (si[i].has_tail_call) { priv_stack_mode = NO_PRIV_STACK; break; } } if (priv_stack_mode == PRIV_STACK_UNKNOWN) priv_stack_mode = bpf_enable_priv_stack(env->prog); /* All async_cb subprogs use normal kernel stack. If a particular * subprog appears in both main prog and async_cb subtree, that * subprog will use normal kernel stack to avoid potential nesting. * The reverse subprog traversal ensures when main prog subtree is * checked, the subprogs appearing in async_cb subtrees are already * marked as using normal kernel stack, so stack size checking can * be done properly. */ for (int i = env->subprog_cnt - 1; i >= 0; i--) { if (!i || si[i].is_async_cb) { priv_stack_supported = !i && priv_stack_mode == PRIV_STACK_ADAPTIVE; ret = check_max_stack_depth_subprog(env, i, priv_stack_supported); if (ret < 0) return ret; } } for (int i = 0; i < env->subprog_cnt; i++) { if (si[i].priv_stack_mode == PRIV_STACK_ADAPTIVE) { env->prog->aux->jits_use_priv_stack = true; break; } } return 0; } #ifndef CONFIG_BPF_JIT_ALWAYS_ON static int get_callee_stack_depth(struct bpf_verifier_env *env, const struct bpf_insn *insn, int idx) { int start = idx + insn->imm + 1, subprog; subprog = find_subprog(env, start); if (subprog < 0) { WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", start); return -EFAULT; } return env->subprog_info[subprog].stack_depth; } #endif static int __check_buffer_access(struct bpf_verifier_env *env, const char *buf_info, const struct bpf_reg_state *reg, int regno, int off, int size) { if (off < 0) { verbose(env, "R%d invalid %s buffer access: off=%d, size=%d\n", regno, buf_info, off, size); return -EACCES; } if (!tnum_is_const(reg->var_off) || reg->var_off.value) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); verbose(env, "R%d invalid variable buffer offset: off=%d, var_off=%s\n", regno, off, tn_buf); return -EACCES; } return 0; } static int check_tp_buffer_access(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno, int off, int size) { int err; err = __check_buffer_access(env, "tracepoint", reg, regno, off, size); if (err) return err; if (off + size > env->prog->aux->max_tp_access) env->prog->aux->max_tp_access = off + size; return 0; } static int check_buffer_access(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno, int off, int size, bool zero_size_allowed, u32 *max_access) { const char *buf_info = type_is_rdonly_mem(reg->type) ? "rdonly" : "rdwr"; int err; err = __check_buffer_access(env, buf_info, reg, regno, off, size); if (err) return err; if (off + size > *max_access) *max_access = off + size; return 0; } /* BPF architecture zero extends alu32 ops into 64-bit registesr */ static void zext_32_to_64(struct bpf_reg_state *reg) { reg->var_off = tnum_subreg(reg->var_off); __reg_assign_32_into_64(reg); } /* truncate register to smaller size (in bytes) * must be called with size < BPF_REG_SIZE */ static void coerce_reg_to_size(struct bpf_reg_state *reg, int size) { u64 mask; /* clear high bits in bit representation */ reg->var_off = tnum_cast(reg->var_off, size); /* fix arithmetic bounds */ mask = ((u64)1 << (size * 8)) - 1; if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) { reg->umin_value &= mask; reg->umax_value &= mask; } else { reg->umin_value = 0; reg->umax_value = mask; } reg->smin_value = reg->umin_value; reg->smax_value = reg->umax_value; /* If size is smaller than 32bit register the 32bit register * values are also truncated so we push 64-bit bounds into * 32-bit bounds. Above were truncated < 32-bits already. */ if (size < 4) __mark_reg32_unbounded(reg); reg_bounds_sync(reg); } static void set_sext64_default_val(struct bpf_reg_state *reg, int size) { if (size == 1) { reg->smin_value = reg->s32_min_value = S8_MIN; reg->smax_value = reg->s32_max_value = S8_MAX; } else if (size == 2) { reg->smin_value = reg->s32_min_value = S16_MIN; reg->smax_value = reg->s32_max_value = S16_MAX; } else { /* size == 4 */ reg->smin_value = reg->s32_min_value = S32_MIN; reg->smax_value = reg->s32_max_value = S32_MAX; } reg->umin_value = reg->u32_min_value = 0; reg->umax_value = U64_MAX; reg->u32_max_value = U32_MAX; reg->var_off = tnum_unknown; } static void coerce_reg_to_size_sx(struct bpf_reg_state *reg, int size) { s64 init_s64_max, init_s64_min, s64_max, s64_min, u64_cval; u64 top_smax_value, top_smin_value; u64 num_bits = size * 8; if (tnum_is_const(reg->var_off)) { u64_cval = reg->var_off.value; if (size == 1) reg->var_off = tnum_const((s8)u64_cval); else if (size == 2) reg->var_off = tnum_const((s16)u64_cval); else /* size == 4 */ reg->var_off = tnum_const((s32)u64_cval); u64_cval = reg->var_off.value; reg->smax_value = reg->smin_value = u64_cval; reg->umax_value = reg->umin_value = u64_cval; reg->s32_max_value = reg->s32_min_value = u64_cval; reg->u32_max_value = reg->u32_min_value = u64_cval; return; } top_smax_value = ((u64)reg->smax_value >> num_bits) << num_bits; top_smin_value = ((u64)reg->smin_value >> num_bits) << num_bits; if (top_smax_value != top_smin_value) goto out; /* find the s64_min and s64_min after sign extension */ if (size == 1) { init_s64_max = (s8)reg->smax_value; init_s64_min = (s8)reg->smin_value; } else if (size == 2) { init_s64_max = (s16)reg->smax_value; init_s64_min = (s16)reg->smin_value; } else { init_s64_max = (s32)reg->smax_value; init_s64_min = (s32)reg->smin_value; } s64_max = max(init_s64_max, init_s64_min); s64_min = min(init_s64_max, init_s64_min); /* both of s64_max/s64_min positive or negative */ if ((s64_max >= 0) == (s64_min >= 0)) { reg->s32_min_value = reg->smin_value = s64_min; reg->s32_max_value = reg->smax_value = s64_max; reg->u32_min_value = reg->umin_value = s64_min; reg->u32_max_value = reg->umax_value = s64_max; reg->var_off = tnum_range(s64_min, s64_max); return; } out: set_sext64_default_val(reg, size); } static void set_sext32_default_val(struct bpf_reg_state *reg, int size) { if (size == 1) { reg->s32_min_value = S8_MIN; reg->s32_max_value = S8_MAX; } else { /* size == 2 */ reg->s32_min_value = S16_MIN; reg->s32_max_value = S16_MAX; } reg->u32_min_value = 0; reg->u32_max_value = U32_MAX; reg->var_off = tnum_subreg(tnum_unknown); } static void coerce_subreg_to_size_sx(struct bpf_reg_state *reg, int size) { s32 init_s32_max, init_s32_min, s32_max, s32_min, u32_val; u32 top_smax_value, top_smin_value; u32 num_bits = size * 8; if (tnum_is_const(reg->var_off)) { u32_val = reg->var_off.value; if (size == 1) reg->var_off = tnum_const((s8)u32_val); else reg->var_off = tnum_const((s16)u32_val); u32_val = reg->var_off.value; reg->s32_min_value = reg->s32_max_value = u32_val; reg->u32_min_value = reg->u32_max_value = u32_val; return; } top_smax_value = ((u32)reg->s32_max_value >> num_bits) << num_bits; top_smin_value = ((u32)reg->s32_min_value >> num_bits) << num_bits; if (top_smax_value != top_smin_value) goto out; /* find the s32_min and s32_min after sign extension */ if (size == 1) { init_s32_max = (s8)reg->s32_max_value; init_s32_min = (s8)reg->s32_min_value; } else { /* size == 2 */ init_s32_max = (s16)reg->s32_max_value; init_s32_min = (s16)reg->s32_min_value; } s32_max = max(init_s32_max, init_s32_min); s32_min = min(init_s32_max, init_s32_min); if ((s32_min >= 0) == (s32_max >= 0)) { reg->s32_min_value = s32_min; reg->s32_max_value = s32_max; reg->u32_min_value = (u32)s32_min; reg->u32_max_value = (u32)s32_max; reg->var_off = tnum_subreg(tnum_range(s32_min, s32_max)); return; } out: set_sext32_default_val(reg, size); } static bool bpf_map_is_rdonly(const struct bpf_map *map) { /* A map is considered read-only if the following condition are true: * * 1) BPF program side cannot change any of the map content. The * BPF_F_RDONLY_PROG flag is throughout the lifetime of a map * and was set at map creation time. * 2) The map value(s) have been initialized from user space by a * loader and then "frozen", such that no new map update/delete * operations from syscall side are possible for the rest of * the map's lifetime from that point onwards. * 3) Any parallel/pending map update/delete operations from syscall * side have been completed. Only after that point, it's safe to * assume that map value(s) are immutable. */ return (map->map_flags & BPF_F_RDONLY_PROG) && READ_ONCE(map->frozen) && !bpf_map_write_active(map); } static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val, bool is_ldsx) { void *ptr; u64 addr; int err; err = map->ops->map_direct_value_addr(map, &addr, off); if (err) return err; ptr = (void *)(long)addr + off; switch (size) { case sizeof(u8): *val = is_ldsx ? (s64)*(s8 *)ptr : (u64)*(u8 *)ptr; break; case sizeof(u16): *val = is_ldsx ? (s64)*(s16 *)ptr : (u64)*(u16 *)ptr; break; case sizeof(u32): *val = is_ldsx ? (s64)*(s32 *)ptr : (u64)*(u32 *)ptr; break; case sizeof(u64): *val = *(u64 *)ptr; break; default: return -EINVAL; } return 0; } #define BTF_TYPE_SAFE_RCU(__type) __PASTE(__type, __safe_rcu) #define BTF_TYPE_SAFE_RCU_OR_NULL(__type) __PASTE(__type, __safe_rcu_or_null) #define BTF_TYPE_SAFE_TRUSTED(__type) __PASTE(__type, __safe_trusted) #define BTF_TYPE_SAFE_TRUSTED_OR_NULL(__type) __PASTE(__type, __safe_trusted_or_null) /* * Allow list few fields as RCU trusted or full trusted. * This logic doesn't allow mix tagging and will be removed once GCC supports * btf_type_tag. */ /* RCU trusted: these fields are trusted in RCU CS and never NULL */ BTF_TYPE_SAFE_RCU(struct task_struct) { const cpumask_t *cpus_ptr; struct css_set __rcu *cgroups; struct task_struct __rcu *real_parent; struct task_struct *group_leader; }; BTF_TYPE_SAFE_RCU(struct cgroup) { /* cgrp->kn is always accessible as documented in kernel/cgroup/cgroup.c */ struct kernfs_node *kn; }; BTF_TYPE_SAFE_RCU(struct css_set) { struct cgroup *dfl_cgrp; }; /* RCU trusted: these fields are trusted in RCU CS and can be NULL */ BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct) { struct file __rcu *exe_file; }; /* skb->sk, req->sk are not RCU protected, but we mark them as such * because bpf prog accessible sockets are SOCK_RCU_FREE. */ BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff) { struct sock *sk; }; BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock) { struct sock *sk; }; /* full trusted: these fields are trusted even outside of RCU CS and never NULL */ BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta) { struct seq_file *seq; }; BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task) { struct bpf_iter_meta *meta; struct task_struct *task; }; BTF_TYPE_SAFE_TRUSTED(struct linux_binprm) { struct file *file; }; BTF_TYPE_SAFE_TRUSTED(struct file) { struct inode *f_inode; }; BTF_TYPE_SAFE_TRUSTED(struct dentry) { /* no negative dentry-s in places where bpf can see it */ struct inode *d_inode; }; BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket) { struct sock *sk; }; static bool type_is_rcu(struct bpf_verifier_env *env, struct bpf_reg_state *reg, const char *field_name, u32 btf_id) { BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct task_struct)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct cgroup)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct css_set)); return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu"); } static bool type_is_rcu_or_null(struct bpf_verifier_env *env, struct bpf_reg_state *reg, const char *field_name, u32 btf_id) { BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock)); return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu_or_null"); } static bool type_is_trusted(struct bpf_verifier_env *env, struct bpf_reg_state *reg, const char *field_name, u32 btf_id) { BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct linux_binprm)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct file)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct dentry)); return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted"); } static bool type_is_trusted_or_null(struct bpf_verifier_env *env, struct bpf_reg_state *reg, const char *field_name, u32 btf_id) { BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket)); return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted_or_null"); } static int check_ptr_to_btf_access(struct bpf_verifier_env *env, struct bpf_reg_state *regs, int regno, int off, int size, enum bpf_access_type atype, int value_regno) { struct bpf_reg_state *reg = regs + regno; const struct btf_type *t = btf_type_by_id(reg->btf, reg->btf_id); const char *tname = btf_name_by_offset(reg->btf, t->name_off); const char *field_name = NULL; enum bpf_type_flag flag = 0; u32 btf_id = 0; int ret; if (!env->allow_ptr_leaks) { verbose(env, "'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n", tname); return -EPERM; } if (!env->prog->gpl_compatible && btf_is_kernel(reg->btf)) { verbose(env, "Cannot access kernel 'struct %s' from non-GPL compatible program\n", tname); return -EINVAL; } if (off < 0) { verbose(env, "R%d is ptr_%s invalid negative access: off=%d\n", regno, tname, off); return -EACCES; } if (!tnum_is_const(reg->var_off) || reg->var_off.value) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); verbose(env, "R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n", regno, tname, off, tn_buf); return -EACCES; } if (reg->type & MEM_USER) { verbose(env, "R%d is ptr_%s access user memory: off=%d\n", regno, tname, off); return -EACCES; } if (reg->type & MEM_PERCPU) { verbose(env, "R%d is ptr_%s access percpu memory: off=%d\n", regno, tname, off); return -EACCES; } if (env->ops->btf_struct_access && !type_is_alloc(reg->type) && atype == BPF_WRITE) { if (!btf_is_kernel(reg->btf)) { verbose(env, "verifier internal error: reg->btf must be kernel btf\n"); return -EFAULT; } ret = env->ops->btf_struct_access(&env->log, reg, off, size); } else { /* Writes are permitted with default btf_struct_access for * program allocated objects (which always have ref_obj_id > 0), * but not for untrusted PTR_TO_BTF_ID | MEM_ALLOC. */ if (atype != BPF_READ && !type_is_ptr_alloc_obj(reg->type)) { verbose(env, "only read is supported\n"); return -EACCES; } if (type_is_alloc(reg->type) && !type_is_non_owning_ref(reg->type) && !(reg->type & MEM_RCU) && !reg->ref_obj_id) { verbose(env, "verifier internal error: ref_obj_id for allocated object must be non-zero\n"); return -EFAULT; } ret = btf_struct_access(&env->log, reg, off, size, atype, &btf_id, &flag, &field_name); } if (ret < 0) return ret; if (ret != PTR_TO_BTF_ID) { /* just mark; */ } else if (type_flag(reg->type) & PTR_UNTRUSTED) { /* If this is an untrusted pointer, all pointers formed by walking it * also inherit the untrusted flag. */ flag = PTR_UNTRUSTED; } else if (is_trusted_reg(reg) || is_rcu_reg(reg)) { /* By default any pointer obtained from walking a trusted pointer is no * longer trusted, unless the field being accessed has explicitly been * marked as inheriting its parent's state of trust (either full or RCU). * For example: * 'cgroups' pointer is untrusted if task->cgroups dereference * happened in a sleepable program outside of bpf_rcu_read_lock() * section. In a non-sleepable program it's trusted while in RCU CS (aka MEM_RCU). * Note bpf_rcu_read_unlock() converts MEM_RCU pointers to PTR_UNTRUSTED. * * A regular RCU-protected pointer with __rcu tag can also be deemed * trusted if we are in an RCU CS. Such pointer can be NULL. */ if (type_is_trusted(env, reg, field_name, btf_id)) { flag |= PTR_TRUSTED; } else if (type_is_trusted_or_null(env, reg, field_name, btf_id)) { flag |= PTR_TRUSTED | PTR_MAYBE_NULL; } else if (in_rcu_cs(env) && !type_may_be_null(reg->type)) { if (type_is_rcu(env, reg, field_name, btf_id)) { /* ignore __rcu tag and mark it MEM_RCU */ flag |= MEM_RCU; } else if (flag & MEM_RCU || type_is_rcu_or_null(env, reg, field_name, btf_id)) { /* __rcu tagged pointers can be NULL */ flag |= MEM_RCU | PTR_MAYBE_NULL; /* We always trust them */ if (type_is_rcu_or_null(env, reg, field_name, btf_id) && flag & PTR_UNTRUSTED) flag &= ~PTR_UNTRUSTED; } else if (flag & (MEM_PERCPU | MEM_USER)) { /* keep as-is */ } else { /* walking unknown pointers yields old deprecated PTR_TO_BTF_ID */ clear_trusted_flags(&flag); } } else { /* * If not in RCU CS or MEM_RCU pointer can be NULL then * aggressively mark as untrusted otherwise such * pointers will be plain PTR_TO_BTF_ID without flags * and will be allowed to be passed into helpers for * compat reasons. */ flag = PTR_UNTRUSTED; } } else { /* Old compat. Deprecated */ clear_trusted_flags(&flag); } if (atype == BPF_READ && value_regno >= 0) mark_btf_ld_reg(env, regs, value_regno, ret, reg->btf, btf_id, flag); return 0; } static int check_ptr_to_map_access(struct bpf_verifier_env *env, struct bpf_reg_state *regs, int regno, int off, int size, enum bpf_access_type atype, int value_regno) { struct bpf_reg_state *reg = regs + regno; struct bpf_map *map = reg->map_ptr; struct bpf_reg_state map_reg; enum bpf_type_flag flag = 0; const struct btf_type *t; const char *tname; u32 btf_id; int ret; if (!btf_vmlinux) { verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n"); return -ENOTSUPP; } if (!map->ops->map_btf_id || !*map->ops->map_btf_id) { verbose(env, "map_ptr access not supported for map type %d\n", map->map_type); return -ENOTSUPP; } t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id); tname = btf_name_by_offset(btf_vmlinux, t->name_off); if (!env->allow_ptr_leaks) { verbose(env, "'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n", tname); return -EPERM; } if (off < 0) { verbose(env, "R%d is %s invalid negative access: off=%d\n", regno, tname, off); return -EACCES; } if (atype != BPF_READ) { verbose(env, "only read from %s is supported\n", tname); return -EACCES; } /* Simulate access to a PTR_TO_BTF_ID */ memset(&map_reg, 0, sizeof(map_reg)); mark_btf_ld_reg(env, &map_reg, 0, PTR_TO_BTF_ID, btf_vmlinux, *map->ops->map_btf_id, 0); ret = btf_struct_access(&env->log, &map_reg, off, size, atype, &btf_id, &flag, NULL); if (ret < 0) return ret; if (value_regno >= 0) mark_btf_ld_reg(env, regs, value_regno, ret, btf_vmlinux, btf_id, flag); return 0; } /* Check that the stack access at the given offset is within bounds. The * maximum valid offset is -1. * * The minimum valid offset is -MAX_BPF_STACK for writes, and * -state->allocated_stack for reads. */ static int check_stack_slot_within_bounds(struct bpf_verifier_env *env, s64 off, struct bpf_func_state *state, enum bpf_access_type t) { int min_valid_off; if (t == BPF_WRITE || env->allow_uninit_stack) min_valid_off = -MAX_BPF_STACK; else min_valid_off = -state->allocated_stack; if (off < min_valid_off || off > -1) return -EACCES; return 0; } /* Check that the stack access at 'regno + off' falls within the maximum stack * bounds. * * 'off' includes `regno->offset`, but not its dynamic part (if any). */ static int check_stack_access_within_bounds( struct bpf_verifier_env *env, int regno, int off, int access_size, enum bpf_access_src src, enum bpf_access_type type) { struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *reg = regs + regno; struct bpf_func_state *state = func(env, reg); s64 min_off, max_off; int err; char *err_extra; if (src == ACCESS_HELPER) /* We don't know if helpers are reading or writing (or both). */ err_extra = " indirect access to"; else if (type == BPF_READ) err_extra = " read from"; else err_extra = " write to"; if (tnum_is_const(reg->var_off)) { min_off = (s64)reg->var_off.value + off; max_off = min_off + access_size; } else { if (reg->smax_value >= BPF_MAX_VAR_OFF || reg->smin_value <= -BPF_MAX_VAR_OFF) { verbose(env, "invalid unbounded variable-offset%s stack R%d\n", err_extra, regno); return -EACCES; } min_off = reg->smin_value + off; max_off = reg->smax_value + off + access_size; } err = check_stack_slot_within_bounds(env, min_off, state, type); if (!err && max_off > 0) err = -EINVAL; /* out of stack access into non-negative offsets */ if (!err && access_size < 0) /* access_size should not be negative (or overflow an int); others checks * along the way should have prevented such an access. */ err = -EFAULT; /* invalid negative access size; integer overflow? */ if (err) { if (tnum_is_const(reg->var_off)) { verbose(env, "invalid%s stack R%d off=%d size=%d\n", err_extra, regno, off, access_size); } else { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); verbose(env, "invalid variable-offset%s stack R%d var_off=%s off=%d size=%d\n", err_extra, regno, tn_buf, off, access_size); } return err; } /* Note that there is no stack access with offset zero, so the needed stack * size is -min_off, not -min_off+1. */ return grow_stack_state(env, state, -min_off /* size */); } static bool get_func_retval_range(struct bpf_prog *prog, struct bpf_retval_range *range) { if (prog->type == BPF_PROG_TYPE_LSM && prog->expected_attach_type == BPF_LSM_MAC && !bpf_lsm_get_retval_range(prog, range)) { return true; } return false; } /* check whether memory at (regno + off) is accessible for t = (read | write) * if t==write, value_regno is a register which value is stored into memory * if t==read, value_regno is a register which will receive the value from memory * if t==write && value_regno==-1, some unknown value is stored into memory * if t==read && value_regno==-1, don't care what we read from memory */ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off, int bpf_size, enum bpf_access_type t, int value_regno, bool strict_alignment_once, bool is_ldsx) { struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *reg = regs + regno; int size, err = 0; size = bpf_size_to_bytes(bpf_size); if (size < 0) return size; /* alignment checks will add in reg->off themselves */ err = check_ptr_alignment(env, reg, off, size, strict_alignment_once); if (err) return err; /* for access checks, reg->off is just part of off */ off += reg->off; if (reg->type == PTR_TO_MAP_KEY) { if (t == BPF_WRITE) { verbose(env, "write to change key R%d not allowed\n", regno); return -EACCES; } err = check_mem_region_access(env, regno, off, size, reg->map_ptr->key_size, false); if (err) return err; if (value_regno >= 0) mark_reg_unknown(env, regs, value_regno); } else if (reg->type == PTR_TO_MAP_VALUE) { struct btf_field *kptr_field = NULL; if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) { verbose(env, "R%d leaks addr into map\n", value_regno); return -EACCES; } err = check_map_access_type(env, regno, off, size, t); if (err) return err; err = check_map_access(env, regno, off, size, false, ACCESS_DIRECT); if (err) return err; if (tnum_is_const(reg->var_off)) kptr_field = btf_record_find(reg->map_ptr->record, off + reg->var_off.value, BPF_KPTR | BPF_UPTR); if (kptr_field) { err = check_map_kptr_access(env, regno, value_regno, insn_idx, kptr_field); } else if (t == BPF_READ && value_regno >= 0) { struct bpf_map *map = reg->map_ptr; /* if map is read-only, track its contents as scalars */ if (tnum_is_const(reg->var_off) && bpf_map_is_rdonly(map) && map->ops->map_direct_value_addr) { int map_off = off + reg->var_off.value; u64 val = 0; err = bpf_map_direct_read(map, map_off, size, &val, is_ldsx); if (err) return err; regs[value_regno].type = SCALAR_VALUE; __mark_reg_known(®s[value_regno], val); } else { mark_reg_unknown(env, regs, value_regno); } } } else if (base_type(reg->type) == PTR_TO_MEM) { bool rdonly_mem = type_is_rdonly_mem(reg->type); if (type_may_be_null(reg->type)) { verbose(env, "R%d invalid mem access '%s'\n", regno, reg_type_str(env, reg->type)); return -EACCES; } if (t == BPF_WRITE && rdonly_mem) { verbose(env, "R%d cannot write into %s\n", regno, reg_type_str(env, reg->type)); return -EACCES; } if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) { verbose(env, "R%d leaks addr into mem\n", value_regno); return -EACCES; } err = check_mem_region_access(env, regno, off, size, reg->mem_size, false); if (!err && value_regno >= 0 && (t == BPF_READ || rdonly_mem)) mark_reg_unknown(env, regs, value_regno); } else if (reg->type == PTR_TO_CTX) { bool is_retval = false; struct bpf_retval_range range; enum bpf_reg_type reg_type = SCALAR_VALUE; struct btf *btf = NULL; u32 btf_id = 0; if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) { verbose(env, "R%d leaks addr into ctx\n", value_regno); return -EACCES; } err = check_ptr_off_reg(env, reg, regno); if (err < 0) return err; err = check_ctx_access(env, insn_idx, off, size, t, ®_type, &btf, &btf_id, &is_retval, is_ldsx); if (err) verbose_linfo(env, insn_idx, "; "); if (!err && t == BPF_READ && value_regno >= 0) { /* ctx access returns either a scalar, or a * PTR_TO_PACKET[_META,_END]. In the latter * case, we know the offset is zero. */ if (reg_type == SCALAR_VALUE) { if (is_retval && get_func_retval_range(env->prog, &range)) { err = __mark_reg_s32_range(env, regs, value_regno, range.minval, range.maxval); if (err) return err; } else { mark_reg_unknown(env, regs, value_regno); } } else { mark_reg_known_zero(env, regs, value_regno); if (type_may_be_null(reg_type)) regs[value_regno].id = ++env->id_gen; /* A load of ctx field could have different * actual load size with the one encoded in the * insn. When the dst is PTR, it is for sure not * a sub-register. */ regs[value_regno].subreg_def = DEF_NOT_SUBREG; if (base_type(reg_type) == PTR_TO_BTF_ID) { regs[value_regno].btf = btf; regs[value_regno].btf_id = btf_id; } } regs[value_regno].type = reg_type; } } else if (reg->type == PTR_TO_STACK) { /* Basic bounds checks. */ err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t); if (err) return err; if (t == BPF_READ) err = check_stack_read(env, regno, off, size, value_regno); else err = check_stack_write(env, regno, off, size, value_regno, insn_idx); } else if (reg_is_pkt_pointer(reg)) { if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) { verbose(env, "cannot write into packet\n"); return -EACCES; } if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) { verbose(env, "R%d leaks addr into packet\n", value_regno); return -EACCES; } err = check_packet_access(env, regno, off, size, false); if (!err && t == BPF_READ && value_regno >= 0) mark_reg_unknown(env, regs, value_regno); } else if (reg->type == PTR_TO_FLOW_KEYS) { if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) { verbose(env, "R%d leaks addr into flow keys\n", value_regno); return -EACCES; } err = check_flow_keys_access(env, off, size); if (!err && t == BPF_READ && value_regno >= 0) mark_reg_unknown(env, regs, value_regno); } else if (type_is_sk_pointer(reg->type)) { if (t == BPF_WRITE) { verbose(env, "R%d cannot write into %s\n", regno, reg_type_str(env, reg->type)); return -EACCES; } err = check_sock_access(env, insn_idx, regno, off, size, t); if (!err && value_regno >= 0) mark_reg_unknown(env, regs, value_regno); } else if (reg->type == PTR_TO_TP_BUFFER) { err = check_tp_buffer_access(env, reg, regno, off, size); if (!err && t == BPF_READ && value_regno >= 0) mark_reg_unknown(env, regs, value_regno); } else if (base_type(reg->type) == PTR_TO_BTF_ID && !type_may_be_null(reg->type)) { err = check_ptr_to_btf_access(env, regs, regno, off, size, t, value_regno); } else if (reg->type == CONST_PTR_TO_MAP) { err = check_ptr_to_map_access(env, regs, regno, off, size, t, value_regno); } else if (base_type(reg->type) == PTR_TO_BUF) { bool rdonly_mem = type_is_rdonly_mem(reg->type); u32 *max_access; if (rdonly_mem) { if (t == BPF_WRITE) { verbose(env, "R%d cannot write into %s\n", regno, reg_type_str(env, reg->type)); return -EACCES; } max_access = &env->prog->aux->max_rdonly_access; } else { max_access = &env->prog->aux->max_rdwr_access; } err = check_buffer_access(env, reg, regno, off, size, false, max_access); if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ)) mark_reg_unknown(env, regs, value_regno); } else if (reg->type == PTR_TO_ARENA) { if (t == BPF_READ && value_regno >= 0) mark_reg_unknown(env, regs, value_regno); } else { verbose(env, "R%d invalid mem access '%s'\n", regno, reg_type_str(env, reg->type)); return -EACCES; } if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ && regs[value_regno].type == SCALAR_VALUE) { if (!is_ldsx) /* b/h/w load zero-extends, mark upper bits as known 0 */ coerce_reg_to_size(®s[value_regno], size); else coerce_reg_to_size_sx(®s[value_regno], size); } return err; } static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type type, bool allow_trust_mismatch); static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) { int load_reg; int err; switch (insn->imm) { case BPF_ADD: case BPF_ADD | BPF_FETCH: case BPF_AND: case BPF_AND | BPF_FETCH: case BPF_OR: case BPF_OR | BPF_FETCH: case BPF_XOR: case BPF_XOR | BPF_FETCH: case BPF_XCHG: case BPF_CMPXCHG: break; default: verbose(env, "BPF_ATOMIC uses invalid atomic opcode %02x\n", insn->imm); return -EINVAL; } if (BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) { verbose(env, "invalid atomic operand size\n"); return -EINVAL; } /* check src1 operand */ err = check_reg_arg(env, insn->src_reg, SRC_OP); if (err) return err; /* check src2 operand */ err = check_reg_arg(env, insn->dst_reg, SRC_OP); if (err) return err; if (insn->imm == BPF_CMPXCHG) { /* Check comparison of R0 with memory location */ const u32 aux_reg = BPF_REG_0; err = check_reg_arg(env, aux_reg, SRC_OP); if (err) return err; if (is_pointer_value(env, aux_reg)) { verbose(env, "R%d leaks addr into mem\n", aux_reg); return -EACCES; } } if (is_pointer_value(env, insn->src_reg)) { verbose(env, "R%d leaks addr into mem\n", insn->src_reg); return -EACCES; } if (is_ctx_reg(env, insn->dst_reg) || is_pkt_reg(env, insn->dst_reg) || is_flow_key_reg(env, insn->dst_reg) || is_sk_reg(env, insn->dst_reg) || (is_arena_reg(env, insn->dst_reg) && !bpf_jit_supports_insn(insn, true))) { verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n", insn->dst_reg, reg_type_str(env, reg_state(env, insn->dst_reg)->type)); return -EACCES; } if (insn->imm & BPF_FETCH) { if (insn->imm == BPF_CMPXCHG) load_reg = BPF_REG_0; else load_reg = insn->src_reg; /* check and record load of old value */ err = check_reg_arg(env, load_reg, DST_OP); if (err) return err; } else { /* This instruction accesses a memory location but doesn't * actually load it into a register. */ load_reg = -1; } /* Check whether we can read the memory, with second call for fetch * case to simulate the register fill. */ err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_READ, -1, true, false); if (!err && load_reg >= 0) err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_READ, load_reg, true, false); if (err) return err; if (is_arena_reg(env, insn->dst_reg)) { err = save_aux_ptr_type(env, PTR_TO_ARENA, false); if (err) return err; } /* Check whether we can write into the same memory. */ err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_WRITE, -1, true, false); if (err) return err; return 0; } /* When register 'regno' is used to read the stack (either directly or through * a helper function) make sure that it's within stack boundary and, depending * on the access type and privileges, that all elements of the stack are * initialized. * * 'off' includes 'regno->off', but not its dynamic part (if any). * * All registers that have been spilled on the stack in the slots within the * read offsets are marked as read. */ static int check_stack_range_initialized( struct bpf_verifier_env *env, int regno, int off, int access_size, bool zero_size_allowed, enum bpf_access_src type, struct bpf_call_arg_meta *meta) { struct bpf_reg_state *reg = reg_state(env, regno); struct bpf_func_state *state = func(env, reg); int err, min_off, max_off, i, j, slot, spi; char *err_extra = type == ACCESS_HELPER ? " indirect" : ""; enum bpf_access_type bounds_check_type; /* Some accesses can write anything into the stack, others are * read-only. */ bool clobber = false; if (access_size == 0 && !zero_size_allowed) { verbose(env, "invalid zero-sized read\n"); return -EACCES; } if (type == ACCESS_HELPER) { /* The bounds checks for writes are more permissive than for * reads. However, if raw_mode is not set, we'll do extra * checks below. */ bounds_check_type = BPF_WRITE; clobber = true; } else { bounds_check_type = BPF_READ; } err = check_stack_access_within_bounds(env, regno, off, access_size, type, bounds_check_type); if (err) return err; if (tnum_is_const(reg->var_off)) { min_off = max_off = reg->var_off.value + off; } else { /* Variable offset is prohibited for unprivileged mode for * simplicity since it requires corresponding support in * Spectre masking for stack ALU. * See also retrieve_ptr_limit(). */ if (!env->bypass_spec_v1) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n", regno, err_extra, tn_buf); return -EACCES; } /* Only initialized buffer on stack is allowed to be accessed * with variable offset. With uninitialized buffer it's hard to * guarantee that whole memory is marked as initialized on * helper return since specific bounds are unknown what may * cause uninitialized stack leaking. */ if (meta && meta->raw_mode) meta = NULL; min_off = reg->smin_value + off; max_off = reg->smax_value + off; } if (meta && meta->raw_mode) { /* Ensure we won't be overwriting dynptrs when simulating byte * by byte access in check_helper_call using meta.access_size. * This would be a problem if we have a helper in the future * which takes: * * helper(uninit_mem, len, dynptr) * * Now, uninint_mem may overlap with dynptr pointer. Hence, it * may end up writing to dynptr itself when touching memory from * arg 1. This can be relaxed on a case by case basis for known * safe cases, but reject due to the possibilitiy of aliasing by * default. */ for (i = min_off; i < max_off + access_size; i++) { int stack_off = -i - 1; spi = __get_spi(i); /* raw_mode may write past allocated_stack */ if (state->allocated_stack <= stack_off) continue; if (state->stack[spi].slot_type[stack_off % BPF_REG_SIZE] == STACK_DYNPTR) { verbose(env, "potential write to dynptr at off=%d disallowed\n", i); return -EACCES; } } meta->access_size = access_size; meta->regno = regno; return 0; } for (i = min_off; i < max_off + access_size; i++) { u8 *stype; slot = -i - 1; spi = slot / BPF_REG_SIZE; if (state->allocated_stack <= slot) { verbose(env, "verifier bug: allocated_stack too small"); return -EFAULT; } stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE]; if (*stype == STACK_MISC) goto mark; if ((*stype == STACK_ZERO) || (*stype == STACK_INVALID && env->allow_uninit_stack)) { if (clobber) { /* helper can write anything into the stack */ *stype = STACK_MISC; } goto mark; } if (is_spilled_reg(&state->stack[spi]) && (state->stack[spi].spilled_ptr.type == SCALAR_VALUE || env->allow_ptr_leaks)) { if (clobber) { __mark_reg_unknown(env, &state->stack[spi].spilled_ptr); for (j = 0; j < BPF_REG_SIZE; j++) scrub_spilled_slot(&state->stack[spi].slot_type[j]); } goto mark; } if (tnum_is_const(reg->var_off)) { verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n", err_extra, regno, min_off, i - min_off, access_size); } else { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n", err_extra, regno, tn_buf, i - min_off, access_size); } return -EACCES; mark: /* reading any byte out of 8-byte 'spill_slot' will cause * the whole slot to be marked as 'read' */ mark_reg_read(env, &state->stack[spi].spilled_ptr, state->stack[spi].spilled_ptr.parent, REG_LIVE_READ64); /* We do not set REG_LIVE_WRITTEN for stack slot, as we can not * be sure that whether stack slot is written to or not. Hence, * we must still conservatively propagate reads upwards even if * helper may write to the entire memory range. */ } return 0; } static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, int access_size, enum bpf_access_type access_type, bool zero_size_allowed, struct bpf_call_arg_meta *meta) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; u32 *max_access; switch (base_type(reg->type)) { case PTR_TO_PACKET: case PTR_TO_PACKET_META: return check_packet_access(env, regno, reg->off, access_size, zero_size_allowed); case PTR_TO_MAP_KEY: if (access_type == BPF_WRITE) { verbose(env, "R%d cannot write into %s\n", regno, reg_type_str(env, reg->type)); return -EACCES; } return check_mem_region_access(env, regno, reg->off, access_size, reg->map_ptr->key_size, false); case PTR_TO_MAP_VALUE: if (check_map_access_type(env, regno, reg->off, access_size, access_type)) return -EACCES; return check_map_access(env, regno, reg->off, access_size, zero_size_allowed, ACCESS_HELPER); case PTR_TO_MEM: if (type_is_rdonly_mem(reg->type)) { if (access_type == BPF_WRITE) { verbose(env, "R%d cannot write into %s\n", regno, reg_type_str(env, reg->type)); return -EACCES; } } return check_mem_region_access(env, regno, reg->off, access_size, reg->mem_size, zero_size_allowed); case PTR_TO_BUF: if (type_is_rdonly_mem(reg->type)) { if (access_type == BPF_WRITE) { verbose(env, "R%d cannot write into %s\n", regno, reg_type_str(env, reg->type)); return -EACCES; } max_access = &env->prog->aux->max_rdonly_access; } else { max_access = &env->prog->aux->max_rdwr_access; } return check_buffer_access(env, reg, regno, reg->off, access_size, zero_size_allowed, max_access); case PTR_TO_STACK: return check_stack_range_initialized( env, regno, reg->off, access_size, zero_size_allowed, ACCESS_HELPER, meta); case PTR_TO_BTF_ID: return check_ptr_to_btf_access(env, regs, regno, reg->off, access_size, BPF_READ, -1); case PTR_TO_CTX: /* in case the function doesn't know how to access the context, * (because we are in a program of type SYSCALL for example), we * can not statically check its size. * Dynamically check it now. */ if (!env->ops->convert_ctx_access) { int offset = access_size - 1; /* Allow zero-byte read from PTR_TO_CTX */ if (access_size == 0) return zero_size_allowed ? 0 : -EACCES; return check_mem_access(env, env->insn_idx, regno, offset, BPF_B, access_type, -1, false, false); } fallthrough; default: /* scalar_value or invalid ptr */ /* Allow zero-byte read from NULL, regardless of pointer type */ if (zero_size_allowed && access_size == 0 && register_is_null(reg)) return 0; verbose(env, "R%d type=%s ", regno, reg_type_str(env, reg->type)); verbose(env, "expected=%s\n", reg_type_str(env, PTR_TO_STACK)); return -EACCES; } } /* verify arguments to helpers or kfuncs consisting of a pointer and an access * size. * * @regno is the register containing the access size. regno-1 is the register * containing the pointer. */ static int check_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, enum bpf_access_type access_type, bool zero_size_allowed, struct bpf_call_arg_meta *meta) { int err; /* This is used to refine r0 return value bounds for helpers * that enforce this value as an upper bound on return values. * See do_refine_retval_range() for helpers that can refine * the return value. C type of helper is u32 so we pull register * bound from umax_value however, if negative verifier errors * out. Only upper bounds can be learned because retval is an * int type and negative retvals are allowed. */ meta->msize_max_value = reg->umax_value; /* The register is SCALAR_VALUE; the access check happens using * its boundaries. For unprivileged variable accesses, disable * raw mode so that the program is required to initialize all * the memory that the helper could just partially fill up. */ if (!tnum_is_const(reg->var_off)) meta = NULL; if (reg->smin_value < 0) { verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n", regno); return -EACCES; } if (reg->umin_value == 0 && !zero_size_allowed) { verbose(env, "R%d invalid zero-sized read: u64=[%lld,%lld]\n", regno, reg->umin_value, reg->umax_value); return -EACCES; } if (reg->umax_value >= BPF_MAX_VAR_SIZ) { verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", regno); return -EACCES; } err = check_helper_mem_access(env, regno - 1, reg->umax_value, access_type, zero_size_allowed, meta); if (!err) err = mark_chain_precision(env, regno); return err; } static int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, u32 mem_size) { bool may_be_null = type_may_be_null(reg->type); struct bpf_reg_state saved_reg; int err; if (register_is_null(reg)) return 0; /* Assuming that the register contains a value check if the memory * access is safe. Temporarily save and restore the register's state as * the conversion shouldn't be visible to a caller. */ if (may_be_null) { saved_reg = *reg; mark_ptr_not_null_reg(reg); } err = check_helper_mem_access(env, regno, mem_size, BPF_READ, true, NULL); err = err ?: check_helper_mem_access(env, regno, mem_size, BPF_WRITE, true, NULL); if (may_be_null) *reg = saved_reg; return err; } static int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno) { struct bpf_reg_state *mem_reg = &cur_regs(env)[regno - 1]; bool may_be_null = type_may_be_null(mem_reg->type); struct bpf_reg_state saved_reg; struct bpf_call_arg_meta meta; int err; WARN_ON_ONCE(regno < BPF_REG_2 || regno > BPF_REG_5); memset(&meta, 0, sizeof(meta)); if (may_be_null) { saved_reg = *mem_reg; mark_ptr_not_null_reg(mem_reg); } err = check_mem_size_reg(env, reg, regno, BPF_READ, true, &meta); err = err ?: check_mem_size_reg(env, reg, regno, BPF_WRITE, true, &meta); if (may_be_null) *mem_reg = saved_reg; return err; } /* Implementation details: * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL. * bpf_obj_new returns PTR_TO_BTF_ID | MEM_ALLOC | PTR_MAYBE_NULL. * Two bpf_map_lookups (even with the same key) will have different reg->id. * Two separate bpf_obj_new will also have different reg->id. * For traditional PTR_TO_MAP_VALUE or PTR_TO_BTF_ID | MEM_ALLOC, the verifier * clears reg->id after value_or_null->value transition, since the verifier only * cares about the range of access to valid map value pointer and doesn't care * about actual address of the map element. * For maps with 'struct bpf_spin_lock' inside map value the verifier keeps * reg->id > 0 after value_or_null->value transition. By doing so * two bpf_map_lookups will be considered two different pointers that * point to different bpf_spin_locks. Likewise for pointers to allocated objects * returned from bpf_obj_new. * The verifier allows taking only one bpf_spin_lock at a time to avoid * dead-locks. * Since only one bpf_spin_lock is allowed the checks are simpler than * reg_is_refcounted() logic. The verifier needs to remember only * one spin_lock instead of array of acquired_refs. * cur_func(env)->active_locks remembers which map value element or allocated * object got locked and clears it after bpf_spin_unlock. */ static int process_spin_lock(struct bpf_verifier_env *env, int regno, bool is_lock) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; bool is_const = tnum_is_const(reg->var_off); struct bpf_func_state *cur = cur_func(env); u64 val = reg->var_off.value; struct bpf_map *map = NULL; struct btf *btf = NULL; struct btf_record *rec; int err; if (!is_const) { verbose(env, "R%d doesn't have constant offset. bpf_spin_lock has to be at the constant offset\n", regno); return -EINVAL; } if (reg->type == PTR_TO_MAP_VALUE) { map = reg->map_ptr; if (!map->btf) { verbose(env, "map '%s' has to have BTF in order to use bpf_spin_lock\n", map->name); return -EINVAL; } } else { btf = reg->btf; } rec = reg_btf_record(reg); if (!btf_record_has_field(rec, BPF_SPIN_LOCK)) { verbose(env, "%s '%s' has no valid bpf_spin_lock\n", map ? "map" : "local", map ? map->name : "kptr"); return -EINVAL; } if (rec->spin_lock_off != val + reg->off) { verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock' that is at %d\n", val + reg->off, rec->spin_lock_off); return -EINVAL; } if (is_lock) { void *ptr; if (map) ptr = map; else ptr = btf; if (cur->active_locks) { verbose(env, "Locking two bpf_spin_locks are not allowed\n"); return -EINVAL; } err = acquire_lock_state(env, env->insn_idx, REF_TYPE_LOCK, reg->id, ptr); if (err < 0) { verbose(env, "Failed to acquire lock state\n"); return err; } } else { void *ptr; if (map) ptr = map; else ptr = btf; if (!cur->active_locks) { verbose(env, "bpf_spin_unlock without taking a lock\n"); return -EINVAL; } if (release_lock_state(cur_func(env), REF_TYPE_LOCK, reg->id, ptr)) { verbose(env, "bpf_spin_unlock of different lock\n"); return -EINVAL; } invalidate_non_owning_refs(env); } return 0; } static int process_timer_func(struct bpf_verifier_env *env, int regno, struct bpf_call_arg_meta *meta) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; bool is_const = tnum_is_const(reg->var_off); struct bpf_map *map = reg->map_ptr; u64 val = reg->var_off.value; if (!is_const) { verbose(env, "R%d doesn't have constant offset. bpf_timer has to be at the constant offset\n", regno); return -EINVAL; } if (!map->btf) { verbose(env, "map '%s' has to have BTF in order to use bpf_timer\n", map->name); return -EINVAL; } if (!btf_record_has_field(map->record, BPF_TIMER)) { verbose(env, "map '%s' has no valid bpf_timer\n", map->name); return -EINVAL; } if (map->record->timer_off != val + reg->off) { verbose(env, "off %lld doesn't point to 'struct bpf_timer' that is at %d\n", val + reg->off, map->record->timer_off); return -EINVAL; } if (meta->map_ptr) { verbose(env, "verifier bug. Two map pointers in a timer helper\n"); return -EFAULT; } meta->map_uid = reg->map_uid; meta->map_ptr = map; return 0; } static int process_wq_func(struct bpf_verifier_env *env, int regno, struct bpf_kfunc_call_arg_meta *meta) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; struct bpf_map *map = reg->map_ptr; u64 val = reg->var_off.value; if (map->record->wq_off != val + reg->off) { verbose(env, "off %lld doesn't point to 'struct bpf_wq' that is at %d\n", val + reg->off, map->record->wq_off); return -EINVAL; } meta->map.uid = reg->map_uid; meta->map.ptr = map; return 0; } static int process_kptr_func(struct bpf_verifier_env *env, int regno, struct bpf_call_arg_meta *meta) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; struct btf_field *kptr_field; struct bpf_map *map_ptr; struct btf_record *rec; u32 kptr_off; if (type_is_ptr_alloc_obj(reg->type)) { rec = reg_btf_record(reg); } else { /* PTR_TO_MAP_VALUE */ map_ptr = reg->map_ptr; if (!map_ptr->btf) { verbose(env, "map '%s' has to have BTF in order to use bpf_kptr_xchg\n", map_ptr->name); return -EINVAL; } rec = map_ptr->record; meta->map_ptr = map_ptr; } if (!tnum_is_const(reg->var_off)) { verbose(env, "R%d doesn't have constant offset. kptr has to be at the constant offset\n", regno); return -EINVAL; } if (!btf_record_has_field(rec, BPF_KPTR)) { verbose(env, "R%d has no valid kptr\n", regno); return -EINVAL; } kptr_off = reg->off + reg->var_off.value; kptr_field = btf_record_find(rec, kptr_off, BPF_KPTR); if (!kptr_field) { verbose(env, "off=%d doesn't point to kptr\n", kptr_off); return -EACCES; } if (kptr_field->type != BPF_KPTR_REF && kptr_field->type != BPF_KPTR_PERCPU) { verbose(env, "off=%d kptr isn't referenced kptr\n", kptr_off); return -EACCES; } meta->kptr_field = kptr_field; return 0; } /* There are two register types representing a bpf_dynptr, one is PTR_TO_STACK * which points to a stack slot, and the other is CONST_PTR_TO_DYNPTR. * * In both cases we deal with the first 8 bytes, but need to mark the next 8 * bytes as STACK_DYNPTR in case of PTR_TO_STACK. In case of * CONST_PTR_TO_DYNPTR, we are guaranteed to get the beginning of the object. * * Mutability of bpf_dynptr is at two levels, one is at the level of struct * bpf_dynptr itself, i.e. whether the helper is receiving a pointer to struct * bpf_dynptr or pointer to const struct bpf_dynptr. In the former case, it can * mutate the view of the dynptr and also possibly destroy it. In the latter * case, it cannot mutate the bpf_dynptr itself but it can still mutate the * memory that dynptr points to. * * The verifier will keep track both levels of mutation (bpf_dynptr's in * reg->type and the memory's in reg->dynptr.type), but there is no support for * readonly dynptr view yet, hence only the first case is tracked and checked. * * This is consistent with how C applies the const modifier to a struct object, * where the pointer itself inside bpf_dynptr becomes const but not what it * points to. * * Helpers which do not mutate the bpf_dynptr set MEM_RDONLY in their argument * type, and declare it as 'const struct bpf_dynptr *' in their prototype. */ static int process_dynptr_func(struct bpf_verifier_env *env, int regno, int insn_idx, enum bpf_arg_type arg_type, int clone_ref_obj_id) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; int err; if (reg->type != PTR_TO_STACK && reg->type != CONST_PTR_TO_DYNPTR) { verbose(env, "arg#%d expected pointer to stack or const struct bpf_dynptr\n", regno - 1); return -EINVAL; } /* MEM_UNINIT and MEM_RDONLY are exclusive, when applied to an * ARG_PTR_TO_DYNPTR (or ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_*): */ if ((arg_type & (MEM_UNINIT | MEM_RDONLY)) == (MEM_UNINIT | MEM_RDONLY)) { verbose(env, "verifier internal error: misconfigured dynptr helper type flags\n"); return -EFAULT; } /* MEM_UNINIT - Points to memory that is an appropriate candidate for * constructing a mutable bpf_dynptr object. * * Currently, this is only possible with PTR_TO_STACK * pointing to a region of at least 16 bytes which doesn't * contain an existing bpf_dynptr. * * MEM_RDONLY - Points to a initialized bpf_dynptr that will not be * mutated or destroyed. However, the memory it points to * may be mutated. * * None - Points to a initialized dynptr that can be mutated and * destroyed, including mutation of the memory it points * to. */ if (arg_type & MEM_UNINIT) { int i; if (!is_dynptr_reg_valid_uninit(env, reg)) { verbose(env, "Dynptr has to be an uninitialized dynptr\n"); return -EINVAL; } /* we write BPF_DW bits (8 bytes) at a time */ for (i = 0; i < BPF_DYNPTR_SIZE; i += 8) { err = check_mem_access(env, insn_idx, regno, i, BPF_DW, BPF_WRITE, -1, false, false); if (err) return err; } err = mark_stack_slots_dynptr(env, reg, arg_type, insn_idx, clone_ref_obj_id); } else /* MEM_RDONLY and None case from above */ { /* For the reg->type == PTR_TO_STACK case, bpf_dynptr is never const */ if (reg->type == CONST_PTR_TO_DYNPTR && !(arg_type & MEM_RDONLY)) { verbose(env, "cannot pass pointer to const bpf_dynptr, the helper mutates it\n"); return -EINVAL; } if (!is_dynptr_reg_valid_init(env, reg)) { verbose(env, "Expected an initialized dynptr as arg #%d\n", regno - 1); return -EINVAL; } /* Fold modifiers (in this case, MEM_RDONLY) when checking expected type */ if (!is_dynptr_type_expected(env, reg, arg_type & ~MEM_RDONLY)) { verbose(env, "Expected a dynptr of type %s as arg #%d\n", dynptr_type_str(arg_to_dynptr_type(arg_type)), regno - 1); return -EINVAL; } err = mark_dynptr_read(env, reg); } return err; } static u32 iter_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int spi) { struct bpf_func_state *state = func(env, reg); return state->stack[spi].spilled_ptr.ref_obj_id; } static bool is_iter_kfunc(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY); } static bool is_iter_new_kfunc(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_ITER_NEW; } static bool is_iter_next_kfunc(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_ITER_NEXT; } static bool is_iter_destroy_kfunc(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_ITER_DESTROY; } static bool is_kfunc_arg_iter(struct bpf_kfunc_call_arg_meta *meta, int arg_idx, const struct btf_param *arg) { /* btf_check_iter_kfuncs() guarantees that first argument of any iter * kfunc is iter state pointer */ if (is_iter_kfunc(meta)) return arg_idx == 0; /* iter passed as an argument to a generic kfunc */ return btf_param_match_suffix(meta->btf, arg, "__iter"); } static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_idx, struct bpf_kfunc_call_arg_meta *meta) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; const struct btf_type *t; int spi, err, i, nr_slots, btf_id; if (reg->type != PTR_TO_STACK) { verbose(env, "arg#%d expected pointer to an iterator on stack\n", regno - 1); return -EINVAL; } /* For iter_{new,next,destroy} functions, btf_check_iter_kfuncs() * ensures struct convention, so we wouldn't need to do any BTF * validation here. But given iter state can be passed as a parameter * to any kfunc, if arg has "__iter" suffix, we need to be a bit more * conservative here. */ btf_id = btf_check_iter_arg(meta->btf, meta->func_proto, regno - 1); if (btf_id < 0) { verbose(env, "expected valid iter pointer as arg #%d\n", regno - 1); return -EINVAL; } t = btf_type_by_id(meta->btf, btf_id); nr_slots = t->size / BPF_REG_SIZE; if (is_iter_new_kfunc(meta)) { /* bpf_iter_<type>_new() expects pointer to uninit iter state */ if (!is_iter_reg_valid_uninit(env, reg, nr_slots)) { verbose(env, "expected uninitialized iter_%s as arg #%d\n", iter_type_str(meta->btf, btf_id), regno - 1); return -EINVAL; } for (i = 0; i < nr_slots * 8; i += BPF_REG_SIZE) { err = check_mem_access(env, insn_idx, regno, i, BPF_DW, BPF_WRITE, -1, false, false); if (err) return err; } err = mark_stack_slots_iter(env, meta, reg, insn_idx, meta->btf, btf_id, nr_slots); if (err) return err; } else { /* iter_next() or iter_destroy(), as well as any kfunc * accepting iter argument, expect initialized iter state */ err = is_iter_reg_valid_init(env, reg, meta->btf, btf_id, nr_slots); switch (err) { case 0: break; case -EINVAL: verbose(env, "expected an initialized iter_%s as arg #%d\n", iter_type_str(meta->btf, btf_id), regno - 1); return err; case -EPROTO: verbose(env, "expected an RCU CS when using %s\n", meta->func_name); return err; default: return err; } spi = iter_get_spi(env, reg, nr_slots); if (spi < 0) return spi; err = mark_iter_read(env, reg, spi, nr_slots); if (err) return err; /* remember meta->iter info for process_iter_next_call() */ meta->iter.spi = spi; meta->iter.frameno = reg->frameno; meta->ref_obj_id = iter_ref_obj_id(env, reg, spi); if (is_iter_destroy_kfunc(meta)) { err = unmark_stack_slots_iter(env, reg, nr_slots); if (err) return err; } } return 0; } /* Look for a previous loop entry at insn_idx: nearest parent state * stopped at insn_idx with callsites matching those in cur->frame. */ static struct bpf_verifier_state *find_prev_entry(struct bpf_verifier_env *env, struct bpf_verifier_state *cur, int insn_idx) { struct bpf_verifier_state_list *sl; struct bpf_verifier_state *st; /* Explored states are pushed in stack order, most recent states come first */ sl = *explored_state(env, insn_idx); for (; sl; sl = sl->next) { /* If st->branches != 0 state is a part of current DFS verification path, * hence cur & st for a loop. */ st = &sl->state; if (st->insn_idx == insn_idx && st->branches && same_callsites(st, cur) && st->dfs_depth < cur->dfs_depth) return st; } return NULL; } static void reset_idmap_scratch(struct bpf_verifier_env *env); static bool regs_exact(const struct bpf_reg_state *rold, const struct bpf_reg_state *rcur, struct bpf_idmap *idmap); static void maybe_widen_reg(struct bpf_verifier_env *env, struct bpf_reg_state *rold, struct bpf_reg_state *rcur, struct bpf_idmap *idmap) { if (rold->type != SCALAR_VALUE) return; if (rold->type != rcur->type) return; if (rold->precise || rcur->precise || regs_exact(rold, rcur, idmap)) return; __mark_reg_unknown(env, rcur); } static int widen_imprecise_scalars(struct bpf_verifier_env *env, struct bpf_verifier_state *old, struct bpf_verifier_state *cur) { struct bpf_func_state *fold, *fcur; int i, fr; reset_idmap_scratch(env); for (fr = old->curframe; fr >= 0; fr--) { fold = old->frame[fr]; fcur = cur->frame[fr]; for (i = 0; i < MAX_BPF_REG; i++) maybe_widen_reg(env, &fold->regs[i], &fcur->regs[i], &env->idmap_scratch); for (i = 0; i < fold->allocated_stack / BPF_REG_SIZE; i++) { if (!is_spilled_reg(&fold->stack[i]) || !is_spilled_reg(&fcur->stack[i])) continue; maybe_widen_reg(env, &fold->stack[i].spilled_ptr, &fcur->stack[i].spilled_ptr, &env->idmap_scratch); } } return 0; } static struct bpf_reg_state *get_iter_from_state(struct bpf_verifier_state *cur_st, struct bpf_kfunc_call_arg_meta *meta) { int iter_frameno = meta->iter.frameno; int iter_spi = meta->iter.spi; return &cur_st->frame[iter_frameno]->stack[iter_spi].spilled_ptr; } /* process_iter_next_call() is called when verifier gets to iterator's next * "method" (e.g., bpf_iter_num_next() for numbers iterator) call. We'll refer * to it as just "iter_next()" in comments below. * * BPF verifier relies on a crucial contract for any iter_next() * implementation: it should *eventually* return NULL, and once that happens * it should keep returning NULL. That is, once iterator exhausts elements to * iterate, it should never reset or spuriously return new elements. * * With the assumption of such contract, process_iter_next_call() simulates * a fork in the verifier state to validate loop logic correctness and safety * without having to simulate infinite amount of iterations. * * In current state, we first assume that iter_next() returned NULL and * iterator state is set to DRAINED (BPF_ITER_STATE_DRAINED). In such * conditions we should not form an infinite loop and should eventually reach * exit. * * Besides that, we also fork current state and enqueue it for later * verification. In a forked state we keep iterator state as ACTIVE * (BPF_ITER_STATE_ACTIVE) and assume non-NULL return from iter_next(). We * also bump iteration depth to prevent erroneous infinite loop detection * later on (see iter_active_depths_differ() comment for details). In this * state we assume that we'll eventually loop back to another iter_next() * calls (it could be in exactly same location or in some other instruction, * it doesn't matter, we don't make any unnecessary assumptions about this, * everything revolves around iterator state in a stack slot, not which * instruction is calling iter_next()). When that happens, we either will come * to iter_next() with equivalent state and can conclude that next iteration * will proceed in exactly the same way as we just verified, so it's safe to * assume that loop converges. If not, we'll go on another iteration * simulation with a different input state, until all possible starting states * are validated or we reach maximum number of instructions limit. * * This way, we will either exhaustively discover all possible input states * that iterator loop can start with and eventually will converge, or we'll * effectively regress into bounded loop simulation logic and either reach * maximum number of instructions if loop is not provably convergent, or there * is some statically known limit on number of iterations (e.g., if there is * an explicit `if n > 100 then break;` statement somewhere in the loop). * * Iteration convergence logic in is_state_visited() relies on exact * states comparison, which ignores read and precision marks. * This is necessary because read and precision marks are not finalized * while in the loop. Exact comparison might preclude convergence for * simple programs like below: * * i = 0; * while(iter_next(&it)) * i++; * * At each iteration step i++ would produce a new distinct state and * eventually instruction processing limit would be reached. * * To avoid such behavior speculatively forget (widen) range for * imprecise scalar registers, if those registers were not precise at the * end of the previous iteration and do not match exactly. * * This is a conservative heuristic that allows to verify wide range of programs, * however it precludes verification of programs that conjure an * imprecise value on the first loop iteration and use it as precise on a second. * For example, the following safe program would fail to verify: * * struct bpf_num_iter it; * int arr[10]; * int i = 0, a = 0; * bpf_iter_num_new(&it, 0, 10); * while (bpf_iter_num_next(&it)) { * if (a == 0) { * a = 1; * i = 7; // Because i changed verifier would forget * // it's range on second loop entry. * } else { * arr[i] = 42; // This would fail to verify. * } * } * bpf_iter_num_destroy(&it); */ static int process_iter_next_call(struct bpf_verifier_env *env, int insn_idx, struct bpf_kfunc_call_arg_meta *meta) { struct bpf_verifier_state *cur_st = env->cur_state, *queued_st, *prev_st; struct bpf_func_state *cur_fr = cur_st->frame[cur_st->curframe], *queued_fr; struct bpf_reg_state *cur_iter, *queued_iter; BTF_TYPE_EMIT(struct bpf_iter); cur_iter = get_iter_from_state(cur_st, meta); if (cur_iter->iter.state != BPF_ITER_STATE_ACTIVE && cur_iter->iter.state != BPF_ITER_STATE_DRAINED) { verbose(env, "verifier internal error: unexpected iterator state %d (%s)\n", cur_iter->iter.state, iter_state_str(cur_iter->iter.state)); return -EFAULT; } if (cur_iter->iter.state == BPF_ITER_STATE_ACTIVE) { /* Because iter_next() call is a checkpoint is_state_visitied() * should guarantee parent state with same call sites and insn_idx. */ if (!cur_st->parent || cur_st->parent->insn_idx != insn_idx || !same_callsites(cur_st->parent, cur_st)) { verbose(env, "bug: bad parent state for iter next call"); return -EFAULT; } /* Note cur_st->parent in the call below, it is necessary to skip * checkpoint created for cur_st by is_state_visited() * right at this instruction. */ prev_st = find_prev_entry(env, cur_st->parent, insn_idx); /* branch out active iter state */ queued_st = push_stack(env, insn_idx + 1, insn_idx, false); if (!queued_st) return -ENOMEM; queued_iter = get_iter_from_state(queued_st, meta); queued_iter->iter.state = BPF_ITER_STATE_ACTIVE; queued_iter->iter.depth++; if (prev_st) widen_imprecise_scalars(env, prev_st, queued_st); queued_fr = queued_st->frame[queued_st->curframe]; mark_ptr_not_null_reg(&queued_fr->regs[BPF_REG_0]); } /* switch to DRAINED state, but keep the depth unchanged */ /* mark current iter state as drained and assume returned NULL */ cur_iter->iter.state = BPF_ITER_STATE_DRAINED; __mark_reg_const_zero(env, &cur_fr->regs[BPF_REG_0]); return 0; } static bool arg_type_is_mem_size(enum bpf_arg_type type) { return type == ARG_CONST_SIZE || type == ARG_CONST_SIZE_OR_ZERO; } static bool arg_type_is_raw_mem(enum bpf_arg_type type) { return base_type(type) == ARG_PTR_TO_MEM && type & MEM_UNINIT; } static bool arg_type_is_release(enum bpf_arg_type type) { return type & OBJ_RELEASE; } static bool arg_type_is_dynptr(enum bpf_arg_type type) { return base_type(type) == ARG_PTR_TO_DYNPTR; } static int resolve_map_arg_type(struct bpf_verifier_env *env, const struct bpf_call_arg_meta *meta, enum bpf_arg_type *arg_type) { if (!meta->map_ptr) { /* kernel subsystem misconfigured verifier */ verbose(env, "invalid map_ptr to access map->type\n"); return -EACCES; } switch (meta->map_ptr->map_type) { case BPF_MAP_TYPE_SOCKMAP: case BPF_MAP_TYPE_SOCKHASH: if (*arg_type == ARG_PTR_TO_MAP_VALUE) { *arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON; } else { verbose(env, "invalid arg_type for sockmap/sockhash\n"); return -EINVAL; } break; case BPF_MAP_TYPE_BLOOM_FILTER: if (meta->func_id == BPF_FUNC_map_peek_elem) *arg_type = ARG_PTR_TO_MAP_VALUE; break; default: break; } return 0; } struct bpf_reg_types { const enum bpf_reg_type types[10]; u32 *btf_id; }; static const struct bpf_reg_types sock_types = { .types = { PTR_TO_SOCK_COMMON, PTR_TO_SOCKET, PTR_TO_TCP_SOCK, PTR_TO_XDP_SOCK, }, }; #ifdef CONFIG_NET static const struct bpf_reg_types btf_id_sock_common_types = { .types = { PTR_TO_SOCK_COMMON, PTR_TO_SOCKET, PTR_TO_TCP_SOCK, PTR_TO_XDP_SOCK, PTR_TO_BTF_ID, PTR_TO_BTF_ID | PTR_TRUSTED, }, .btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON], }; #endif static const struct bpf_reg_types mem_types = { .types = { PTR_TO_STACK, PTR_TO_PACKET, PTR_TO_PACKET_META, PTR_TO_MAP_KEY, PTR_TO_MAP_VALUE, PTR_TO_MEM, PTR_TO_MEM | MEM_RINGBUF, PTR_TO_BUF, PTR_TO_BTF_ID | PTR_TRUSTED, }, }; static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE, PTR_TO_BTF_ID | MEM_ALLOC, } }; static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } }; static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } }; static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } }; static const struct bpf_reg_types ringbuf_mem_types = { .types = { PTR_TO_MEM | MEM_RINGBUF } }; static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } }; static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID, PTR_TO_BTF_ID | PTR_TRUSTED, PTR_TO_BTF_ID | MEM_RCU, }, }; static const struct bpf_reg_types percpu_btf_ptr_types = { .types = { PTR_TO_BTF_ID | MEM_PERCPU, PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU, PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED, } }; static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } }; static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } }; static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } }; static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE } }; static const struct bpf_reg_types kptr_xchg_dest_types = { .types = { PTR_TO_MAP_VALUE, PTR_TO_BTF_ID | MEM_ALLOC } }; static const struct bpf_reg_types dynptr_types = { .types = { PTR_TO_STACK, CONST_PTR_TO_DYNPTR, } }; static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { [ARG_PTR_TO_MAP_KEY] = &mem_types, [ARG_PTR_TO_MAP_VALUE] = &mem_types, [ARG_CONST_SIZE] = &scalar_types, [ARG_CONST_SIZE_OR_ZERO] = &scalar_types, [ARG_CONST_ALLOC_SIZE_OR_ZERO] = &scalar_types, [ARG_CONST_MAP_PTR] = &const_map_ptr_types, [ARG_PTR_TO_CTX] = &context_types, [ARG_PTR_TO_SOCK_COMMON] = &sock_types, #ifdef CONFIG_NET [ARG_PTR_TO_BTF_ID_SOCK_COMMON] = &btf_id_sock_common_types, #endif [ARG_PTR_TO_SOCKET] = &fullsock_types, [ARG_PTR_TO_BTF_ID] = &btf_ptr_types, [ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types, [ARG_PTR_TO_MEM] = &mem_types, [ARG_PTR_TO_RINGBUF_MEM] = &ringbuf_mem_types, [ARG_PTR_TO_PERCPU_BTF_ID] = &percpu_btf_ptr_types, [ARG_PTR_TO_FUNC] = &func_ptr_types, [ARG_PTR_TO_STACK] = &stack_ptr_types, [ARG_PTR_TO_CONST_STR] = &const_str_ptr_types, [ARG_PTR_TO_TIMER] = &timer_types, [ARG_KPTR_XCHG_DEST] = &kptr_xchg_dest_types, [ARG_PTR_TO_DYNPTR] = &dynptr_types, }; static int check_reg_type(struct bpf_verifier_env *env, u32 regno, enum bpf_arg_type arg_type, const u32 *arg_btf_id, struct bpf_call_arg_meta *meta) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; enum bpf_reg_type expected, type = reg->type; const struct bpf_reg_types *compatible; int i, j; compatible = compatible_reg_types[base_type(arg_type)]; if (!compatible) { verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type); return -EFAULT; } /* ARG_PTR_TO_MEM + RDONLY is compatible with PTR_TO_MEM and PTR_TO_MEM + RDONLY, * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM and NOT with PTR_TO_MEM + RDONLY * * Same for MAYBE_NULL: * * ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL, * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL * * ARG_PTR_TO_MEM is compatible with PTR_TO_MEM that is tagged with a dynptr type. * * Therefore we fold these flags depending on the arg_type before comparison. */ if (arg_type & MEM_RDONLY) type &= ~MEM_RDONLY; if (arg_type & PTR_MAYBE_NULL) type &= ~PTR_MAYBE_NULL; if (base_type(arg_type) == ARG_PTR_TO_MEM) type &= ~DYNPTR_TYPE_FLAG_MASK; /* Local kptr types are allowed as the source argument of bpf_kptr_xchg */ if (meta->func_id == BPF_FUNC_kptr_xchg && type_is_alloc(type) && regno == BPF_REG_2) { type &= ~MEM_ALLOC; type &= ~MEM_PERCPU; } for (i = 0; i < ARRAY_SIZE(compatible->types); i++) { expected = compatible->types[i]; if (expected == NOT_INIT) break; if (type == expected) goto found; } verbose(env, "R%d type=%s expected=", regno, reg_type_str(env, reg->type)); for (j = 0; j + 1 < i; j++) verbose(env, "%s, ", reg_type_str(env, compatible->types[j])); verbose(env, "%s\n", reg_type_str(env, compatible->types[j])); return -EACCES; found: if (base_type(reg->type) != PTR_TO_BTF_ID) return 0; if (compatible == &mem_types) { if (!(arg_type & MEM_RDONLY)) { verbose(env, "%s() may write into memory pointed by R%d type=%s\n", func_id_name(meta->func_id), regno, reg_type_str(env, reg->type)); return -EACCES; } return 0; } switch ((int)reg->type) { case PTR_TO_BTF_ID: case PTR_TO_BTF_ID | PTR_TRUSTED: case PTR_TO_BTF_ID | PTR_TRUSTED | PTR_MAYBE_NULL: case PTR_TO_BTF_ID | MEM_RCU: case PTR_TO_BTF_ID | PTR_MAYBE_NULL: case PTR_TO_BTF_ID | PTR_MAYBE_NULL | MEM_RCU: { /* For bpf_sk_release, it needs to match against first member * 'struct sock_common', hence make an exception for it. This * allows bpf_sk_release to work for multiple socket types. */ bool strict_type_match = arg_type_is_release(arg_type) && meta->func_id != BPF_FUNC_sk_release; if (type_may_be_null(reg->type) && (!type_may_be_null(arg_type) || arg_type_is_release(arg_type))) { verbose(env, "Possibly NULL pointer passed to helper arg%d\n", regno); return -EACCES; } if (!arg_btf_id) { if (!compatible->btf_id) { verbose(env, "verifier internal error: missing arg compatible BTF ID\n"); return -EFAULT; } arg_btf_id = compatible->btf_id; } if (meta->func_id == BPF_FUNC_kptr_xchg) { if (map_kptr_match_type(env, meta->kptr_field, reg, regno)) return -EACCES; } else { if (arg_btf_id == BPF_PTR_POISON) { verbose(env, "verifier internal error:"); verbose(env, "R%d has non-overwritten BPF_PTR_POISON type\n", regno); return -EACCES; } if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off, btf_vmlinux, *arg_btf_id, strict_type_match)) { verbose(env, "R%d is of type %s but %s is expected\n", regno, btf_type_name(reg->btf, reg->btf_id), btf_type_name(btf_vmlinux, *arg_btf_id)); return -EACCES; } } break; } case PTR_TO_BTF_ID | MEM_ALLOC: case PTR_TO_BTF_ID | MEM_PERCPU | MEM_ALLOC: if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock && meta->func_id != BPF_FUNC_kptr_xchg) { verbose(env, "verifier internal error: unimplemented handling of MEM_ALLOC\n"); return -EFAULT; } /* Check if local kptr in src arg matches kptr in dst arg */ if (meta->func_id == BPF_FUNC_kptr_xchg && regno == BPF_REG_2) { if (map_kptr_match_type(env, meta->kptr_field, reg, regno)) return -EACCES; } break; case PTR_TO_BTF_ID | MEM_PERCPU: case PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU: case PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED: /* Handled by helper specific checks */ break; default: verbose(env, "verifier internal error: invalid PTR_TO_BTF_ID register for type match\n"); return -EFAULT; } return 0; } static struct btf_field * reg_find_field_offset(const struct bpf_reg_state *reg, s32 off, u32 fields) { struct btf_field *field; struct btf_record *rec; rec = reg_btf_record(reg); if (!rec) return NULL; field = btf_record_find(rec, off, fields); if (!field) return NULL; return field; } static int check_func_arg_reg_off(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno, enum bpf_arg_type arg_type) { u32 type = reg->type; /* When referenced register is passed to release function, its fixed * offset must be 0. * * We will check arg_type_is_release reg has ref_obj_id when storing * meta->release_regno. */ if (arg_type_is_release(arg_type)) { /* ARG_PTR_TO_DYNPTR with OBJ_RELEASE is a bit special, as it * may not directly point to the object being released, but to * dynptr pointing to such object, which might be at some offset * on the stack. In that case, we simply to fallback to the * default handling. */ if (arg_type_is_dynptr(arg_type) && type == PTR_TO_STACK) return 0; /* Doing check_ptr_off_reg check for the offset will catch this * because fixed_off_ok is false, but checking here allows us * to give the user a better error message. */ if (reg->off) { verbose(env, "R%d must have zero offset when passed to release func or trusted arg to kfunc\n", regno); return -EINVAL; } return __check_ptr_off_reg(env, reg, regno, false); } switch (type) { /* Pointer types where both fixed and variable offset is explicitly allowed: */ case PTR_TO_STACK: case PTR_TO_PACKET: case PTR_TO_PACKET_META: case PTR_TO_MAP_KEY: case PTR_TO_MAP_VALUE: case PTR_TO_MEM: case PTR_TO_MEM | MEM_RDONLY: case PTR_TO_MEM | MEM_RINGBUF: case PTR_TO_BUF: case PTR_TO_BUF | MEM_RDONLY: case PTR_TO_ARENA: case SCALAR_VALUE: return 0; /* All the rest must be rejected, except PTR_TO_BTF_ID which allows * fixed offset. */ case PTR_TO_BTF_ID: case PTR_TO_BTF_ID | MEM_ALLOC: case PTR_TO_BTF_ID | PTR_TRUSTED: case PTR_TO_BTF_ID | MEM_RCU: case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF: case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU: /* When referenced PTR_TO_BTF_ID is passed to release function, * its fixed offset must be 0. In the other cases, fixed offset * can be non-zero. This was already checked above. So pass * fixed_off_ok as true to allow fixed offset for all other * cases. var_off always must be 0 for PTR_TO_BTF_ID, hence we * still need to do checks instead of returning. */ return __check_ptr_off_reg(env, reg, regno, true); default: return __check_ptr_off_reg(env, reg, regno, false); } } static struct bpf_reg_state *get_dynptr_arg_reg(struct bpf_verifier_env *env, const struct bpf_func_proto *fn, struct bpf_reg_state *regs) { struct bpf_reg_state *state = NULL; int i; for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) if (arg_type_is_dynptr(fn->arg_type[i])) { if (state) { verbose(env, "verifier internal error: multiple dynptr args\n"); return NULL; } state = ®s[BPF_REG_1 + i]; } if (!state) verbose(env, "verifier internal error: no dynptr arg found\n"); return state; } static int dynptr_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { struct bpf_func_state *state = func(env, reg); int spi; if (reg->type == CONST_PTR_TO_DYNPTR) return reg->id; spi = dynptr_get_spi(env, reg); if (spi < 0) return spi; return state->stack[spi].spilled_ptr.id; } static int dynptr_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { struct bpf_func_state *state = func(env, reg); int spi; if (reg->type == CONST_PTR_TO_DYNPTR) return reg->ref_obj_id; spi = dynptr_get_spi(env, reg); if (spi < 0) return spi; return state->stack[spi].spilled_ptr.ref_obj_id; } static enum bpf_dynptr_type dynptr_get_type(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { struct bpf_func_state *state = func(env, reg); int spi; if (reg->type == CONST_PTR_TO_DYNPTR) return reg->dynptr.type; spi = __get_spi(reg->off); if (spi < 0) { verbose(env, "verifier internal error: invalid spi when querying dynptr type\n"); return BPF_DYNPTR_TYPE_INVALID; } return state->stack[spi].spilled_ptr.dynptr.type; } static int check_reg_const_str(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno) { struct bpf_map *map = reg->map_ptr; int err; int map_off; u64 map_addr; char *str_ptr; if (reg->type != PTR_TO_MAP_VALUE) return -EINVAL; if (!bpf_map_is_rdonly(map)) { verbose(env, "R%d does not point to a readonly map'\n", regno); return -EACCES; } if (!tnum_is_const(reg->var_off)) { verbose(env, "R%d is not a constant address'\n", regno); return -EACCES; } if (!map->ops->map_direct_value_addr) { verbose(env, "no direct value access support for this map type\n"); return -EACCES; } err = check_map_access(env, regno, reg->off, map->value_size - reg->off, false, ACCESS_HELPER); if (err) return err; map_off = reg->off + reg->var_off.value; err = map->ops->map_direct_value_addr(map, &map_addr, map_off); if (err) { verbose(env, "direct value access on string failed\n"); return err; } str_ptr = (char *)(long)(map_addr); if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) { verbose(env, "string is not zero-terminated\n"); return -EINVAL; } return 0; } static int check_func_arg(struct bpf_verifier_env *env, u32 arg, struct bpf_call_arg_meta *meta, const struct bpf_func_proto *fn, int insn_idx) { u32 regno = BPF_REG_1 + arg; struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; enum bpf_arg_type arg_type = fn->arg_type[arg]; enum bpf_reg_type type = reg->type; u32 *arg_btf_id = NULL; int err = 0; if (arg_type == ARG_DONTCARE) return 0; err = check_reg_arg(env, regno, SRC_OP); if (err) return err; if (arg_type == ARG_ANYTHING) { if (is_pointer_value(env, regno)) { verbose(env, "R%d leaks addr into helper function\n", regno); return -EACCES; } return 0; } if (type_is_pkt_pointer(type) && !may_access_direct_pkt_data(env, meta, BPF_READ)) { verbose(env, "helper access to the packet is not allowed\n"); return -EACCES; } if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE) { err = resolve_map_arg_type(env, meta, &arg_type); if (err) return err; } if (register_is_null(reg) && type_may_be_null(arg_type)) /* A NULL register has a SCALAR_VALUE type, so skip * type checking. */ goto skip_type_check; /* arg_btf_id and arg_size are in a union. */ if (base_type(arg_type) == ARG_PTR_TO_BTF_ID || base_type(arg_type) == ARG_PTR_TO_SPIN_LOCK) arg_btf_id = fn->arg_btf_id[arg]; err = check_reg_type(env, regno, arg_type, arg_btf_id, meta); if (err) return err; err = check_func_arg_reg_off(env, reg, regno, arg_type); if (err) return err; skip_type_check: if (arg_type_is_release(arg_type)) { if (arg_type_is_dynptr(arg_type)) { struct bpf_func_state *state = func(env, reg); int spi; /* Only dynptr created on stack can be released, thus * the get_spi and stack state checks for spilled_ptr * should only be done before process_dynptr_func for * PTR_TO_STACK. */ if (reg->type == PTR_TO_STACK) { spi = dynptr_get_spi(env, reg); if (spi < 0 || !state->stack[spi].spilled_ptr.ref_obj_id) { verbose(env, "arg %d is an unacquired reference\n", regno); return -EINVAL; } } else { verbose(env, "cannot release unowned const bpf_dynptr\n"); return -EINVAL; } } else if (!reg->ref_obj_id && !register_is_null(reg)) { verbose(env, "R%d must be referenced when passed to release function\n", regno); return -EINVAL; } if (meta->release_regno) { verbose(env, "verifier internal error: more than one release argument\n"); return -EFAULT; } meta->release_regno = regno; } if (reg->ref_obj_id && base_type(arg_type) != ARG_KPTR_XCHG_DEST) { if (meta->ref_obj_id) { verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n", regno, reg->ref_obj_id, meta->ref_obj_id); return -EFAULT; } meta->ref_obj_id = reg->ref_obj_id; } switch (base_type(arg_type)) { case ARG_CONST_MAP_PTR: /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ if (meta->map_ptr) { /* Use map_uid (which is unique id of inner map) to reject: * inner_map1 = bpf_map_lookup_elem(outer_map, key1) * inner_map2 = bpf_map_lookup_elem(outer_map, key2) * if (inner_map1 && inner_map2) { * timer = bpf_map_lookup_elem(inner_map1); * if (timer) * // mismatch would have been allowed * bpf_timer_init(timer, inner_map2); * } * * Comparing map_ptr is enough to distinguish normal and outer maps. */ if (meta->map_ptr != reg->map_ptr || meta->map_uid != reg->map_uid) { verbose(env, "timer pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n", meta->map_uid, reg->map_uid); return -EINVAL; } } meta->map_ptr = reg->map_ptr; meta->map_uid = reg->map_uid; break; case ARG_PTR_TO_MAP_KEY: /* bpf_map_xxx(..., map_ptr, ..., key) call: * check that [key, key + map->key_size) are within * stack limits and initialized */ if (!meta->map_ptr) { /* in function declaration map_ptr must come before * map_key, so that it's verified and known before * we have to check map_key here. Otherwise it means * that kernel subsystem misconfigured verifier */ verbose(env, "invalid map_ptr to access map->key\n"); return -EACCES; } err = check_helper_mem_access(env, regno, meta->map_ptr->key_size, BPF_READ, false, NULL); break; case ARG_PTR_TO_MAP_VALUE: if (type_may_be_null(arg_type) && register_is_null(reg)) return 0; /* bpf_map_xxx(..., map_ptr, ..., value) call: * check [value, value + map->value_size) validity */ if (!meta->map_ptr) { /* kernel subsystem misconfigured verifier */ verbose(env, "invalid map_ptr to access map->value\n"); return -EACCES; } meta->raw_mode = arg_type & MEM_UNINIT; err = check_helper_mem_access(env, regno, meta->map_ptr->value_size, arg_type & MEM_WRITE ? BPF_WRITE : BPF_READ, false, meta); break; case ARG_PTR_TO_PERCPU_BTF_ID: if (!reg->btf_id) { verbose(env, "Helper has invalid btf_id in R%d\n", regno); return -EACCES; } meta->ret_btf = reg->btf; meta->ret_btf_id = reg->btf_id; break; case ARG_PTR_TO_SPIN_LOCK: if (in_rbtree_lock_required_cb(env)) { verbose(env, "can't spin_{lock,unlock} in rbtree cb\n"); return -EACCES; } if (meta->func_id == BPF_FUNC_spin_lock) { err = process_spin_lock(env, regno, true); if (err) return err; } else if (meta->func_id == BPF_FUNC_spin_unlock) { err = process_spin_lock(env, regno, false); if (err) return err; } else { verbose(env, "verifier internal error\n"); return -EFAULT; } break; case ARG_PTR_TO_TIMER: err = process_timer_func(env, regno, meta); if (err) return err; break; case ARG_PTR_TO_FUNC: meta->subprogno = reg->subprogno; break; case ARG_PTR_TO_MEM: /* The access to this pointer is only checked when we hit the * next is_mem_size argument below. */ meta->raw_mode = arg_type & MEM_UNINIT; if (arg_type & MEM_FIXED_SIZE) { err = check_helper_mem_access(env, regno, fn->arg_size[arg], arg_type & MEM_WRITE ? BPF_WRITE : BPF_READ, false, meta); if (err) return err; if (arg_type & MEM_ALIGNED) err = check_ptr_alignment(env, reg, 0, fn->arg_size[arg], true); } break; case ARG_CONST_SIZE: err = check_mem_size_reg(env, reg, regno, fn->arg_type[arg - 1] & MEM_WRITE ? BPF_WRITE : BPF_READ, false, meta); break; case ARG_CONST_SIZE_OR_ZERO: err = check_mem_size_reg(env, reg, regno, fn->arg_type[arg - 1] & MEM_WRITE ? BPF_WRITE : BPF_READ, true, meta); break; case ARG_PTR_TO_DYNPTR: err = process_dynptr_func(env, regno, insn_idx, arg_type, 0); if (err) return err; break; case ARG_CONST_ALLOC_SIZE_OR_ZERO: if (!tnum_is_const(reg->var_off)) { verbose(env, "R%d is not a known constant'\n", regno); return -EACCES; } meta->mem_size = reg->var_off.value; err = mark_chain_precision(env, regno); if (err) return err; break; case ARG_PTR_TO_CONST_STR: { err = check_reg_const_str(env, reg, regno); if (err) return err; break; } case ARG_KPTR_XCHG_DEST: err = process_kptr_func(env, regno, meta); if (err) return err; break; } return err; } static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id) { enum bpf_attach_type eatype = env->prog->expected_attach_type; enum bpf_prog_type type = resolve_prog_type(env->prog); if (func_id != BPF_FUNC_map_update_elem && func_id != BPF_FUNC_map_delete_elem) return false; /* It's not possible to get access to a locked struct sock in these * contexts, so updating is safe. */ switch (type) { case BPF_PROG_TYPE_TRACING: if (eatype == BPF_TRACE_ITER) return true; break; case BPF_PROG_TYPE_SOCK_OPS: /* map_update allowed only via dedicated helpers with event type checks */ if (func_id == BPF_FUNC_map_delete_elem) return true; break; case BPF_PROG_TYPE_SOCKET_FILTER: case BPF_PROG_TYPE_SCHED_CLS: case BPF_PROG_TYPE_SCHED_ACT: case BPF_PROG_TYPE_XDP: case BPF_PROG_TYPE_SK_REUSEPORT: case BPF_PROG_TYPE_FLOW_DISSECTOR: case BPF_PROG_TYPE_SK_LOOKUP: return true; default: break; } verbose(env, "cannot update sockmap in this context\n"); return false; } static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env) { return env->prog->jit_requested && bpf_jit_supports_subprog_tailcalls(); } static int check_map_func_compatibility(struct bpf_verifier_env *env, struct bpf_map *map, int func_id) { if (!map) return 0; /* We need a two way check, first is from map perspective ... */ switch (map->map_type) { case BPF_MAP_TYPE_PROG_ARRAY: if (func_id != BPF_FUNC_tail_call) goto error; break; case BPF_MAP_TYPE_PERF_EVENT_ARRAY: if (func_id != BPF_FUNC_perf_event_read && func_id != BPF_FUNC_perf_event_output && func_id != BPF_FUNC_skb_output && func_id != BPF_FUNC_perf_event_read_value && func_id != BPF_FUNC_xdp_output) goto error; break; case BPF_MAP_TYPE_RINGBUF: if (func_id != BPF_FUNC_ringbuf_output && func_id != BPF_FUNC_ringbuf_reserve && func_id != BPF_FUNC_ringbuf_query && func_id != BPF_FUNC_ringbuf_reserve_dynptr && func_id != BPF_FUNC_ringbuf_submit_dynptr && func_id != BPF_FUNC_ringbuf_discard_dynptr) goto error; break; case BPF_MAP_TYPE_USER_RINGBUF: if (func_id != BPF_FUNC_user_ringbuf_drain) goto error; break; case BPF_MAP_TYPE_STACK_TRACE: if (func_id != BPF_FUNC_get_stackid) goto error; break; case BPF_MAP_TYPE_CGROUP_ARRAY: if (func_id != BPF_FUNC_skb_under_cgroup && func_id != BPF_FUNC_current_task_under_cgroup) goto error; break; case BPF_MAP_TYPE_CGROUP_STORAGE: case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE: if (func_id != BPF_FUNC_get_local_storage) goto error; break; case BPF_MAP_TYPE_DEVMAP: case BPF_MAP_TYPE_DEVMAP_HASH: if (func_id != BPF_FUNC_redirect_map && func_id != BPF_FUNC_map_lookup_elem) goto error; break; /* Restrict bpf side of cpumap and xskmap, open when use-cases * appear. */ case BPF_MAP_TYPE_CPUMAP: if (func_id != BPF_FUNC_redirect_map) goto error; break; case BPF_MAP_TYPE_XSKMAP: if (func_id != BPF_FUNC_redirect_map && func_id != BPF_FUNC_map_lookup_elem) goto error; break; case BPF_MAP_TYPE_ARRAY_OF_MAPS: case BPF_MAP_TYPE_HASH_OF_MAPS: if (func_id != BPF_FUNC_map_lookup_elem) goto error; break; case BPF_MAP_TYPE_SOCKMAP: if (func_id != BPF_FUNC_sk_redirect_map && func_id != BPF_FUNC_sock_map_update && func_id != BPF_FUNC_msg_redirect_map && func_id != BPF_FUNC_sk_select_reuseport && func_id != BPF_FUNC_map_lookup_elem && !may_update_sockmap(env, func_id)) goto error; break; case BPF_MAP_TYPE_SOCKHASH: if (func_id != BPF_FUNC_sk_redirect_hash && func_id != BPF_FUNC_sock_hash_update && func_id != BPF_FUNC_msg_redirect_hash && func_id != BPF_FUNC_sk_select_reuseport && func_id != BPF_FUNC_map_lookup_elem && !may_update_sockmap(env, func_id)) goto error; break; case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY: if (func_id != BPF_FUNC_sk_select_reuseport) goto error; break; case BPF_MAP_TYPE_QUEUE: case BPF_MAP_TYPE_STACK: if (func_id != BPF_FUNC_map_peek_elem && func_id != BPF_FUNC_map_pop_elem && func_id != BPF_FUNC_map_push_elem) goto error; break; case BPF_MAP_TYPE_SK_STORAGE: if (func_id != BPF_FUNC_sk_storage_get && func_id != BPF_FUNC_sk_storage_delete && func_id != BPF_FUNC_kptr_xchg) goto error; break; case BPF_MAP_TYPE_INODE_STORAGE: if (func_id != BPF_FUNC_inode_storage_get && func_id != BPF_FUNC_inode_storage_delete && func_id != BPF_FUNC_kptr_xchg) goto error; break; case BPF_MAP_TYPE_TASK_STORAGE: if (func_id != BPF_FUNC_task_storage_get && func_id != BPF_FUNC_task_storage_delete && func_id != BPF_FUNC_kptr_xchg) goto error; break; case BPF_MAP_TYPE_CGRP_STORAGE: if (func_id != BPF_FUNC_cgrp_storage_get && func_id != BPF_FUNC_cgrp_storage_delete && func_id != BPF_FUNC_kptr_xchg) goto error; break; case BPF_MAP_TYPE_BLOOM_FILTER: if (func_id != BPF_FUNC_map_peek_elem && func_id != BPF_FUNC_map_push_elem) goto error; break; default: break; } /* ... and second from the function itself. */ switch (func_id) { case BPF_FUNC_tail_call: if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) goto error; if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) { verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n"); return -EINVAL; } break; case BPF_FUNC_perf_event_read: case BPF_FUNC_perf_event_output: case BPF_FUNC_perf_event_read_value: case BPF_FUNC_skb_output: case BPF_FUNC_xdp_output: if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) goto error; break; case BPF_FUNC_ringbuf_output: case BPF_FUNC_ringbuf_reserve: case BPF_FUNC_ringbuf_query: case BPF_FUNC_ringbuf_reserve_dynptr: case BPF_FUNC_ringbuf_submit_dynptr: case BPF_FUNC_ringbuf_discard_dynptr: if (map->map_type != BPF_MAP_TYPE_RINGBUF) goto error; break; case BPF_FUNC_user_ringbuf_drain: if (map->map_type != BPF_MAP_TYPE_USER_RINGBUF) goto error; break; case BPF_FUNC_get_stackid: if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) goto error; break; case BPF_FUNC_current_task_under_cgroup: case BPF_FUNC_skb_under_cgroup: if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) goto error; break; case BPF_FUNC_redirect_map: if (map->map_type != BPF_MAP_TYPE_DEVMAP && map->map_type != BPF_MAP_TYPE_DEVMAP_HASH && map->map_type != BPF_MAP_TYPE_CPUMAP && map->map_type != BPF_MAP_TYPE_XSKMAP) goto error; break; case BPF_FUNC_sk_redirect_map: case BPF_FUNC_msg_redirect_map: case BPF_FUNC_sock_map_update: if (map->map_type != BPF_MAP_TYPE_SOCKMAP) goto error; break; case BPF_FUNC_sk_redirect_hash: case BPF_FUNC_msg_redirect_hash: case BPF_FUNC_sock_hash_update: if (map->map_type != BPF_MAP_TYPE_SOCKHASH) goto error; break; case BPF_FUNC_get_local_storage: if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE && map->map_type != BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) goto error; break; case BPF_FUNC_sk_select_reuseport: if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY && map->map_type != BPF_MAP_TYPE_SOCKMAP && map->map_type != BPF_MAP_TYPE_SOCKHASH) goto error; break; case BPF_FUNC_map_pop_elem: if (map->map_type != BPF_MAP_TYPE_QUEUE && map->map_type != BPF_MAP_TYPE_STACK) goto error; break; case BPF_FUNC_map_peek_elem: case BPF_FUNC_map_push_elem: if (map->map_type != BPF_MAP_TYPE_QUEUE && map->map_type != BPF_MAP_TYPE_STACK && map->map_type != BPF_MAP_TYPE_BLOOM_FILTER) goto error; break; case BPF_FUNC_map_lookup_percpu_elem: if (map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY && map->map_type != BPF_MAP_TYPE_PERCPU_HASH && map->map_type != BPF_MAP_TYPE_LRU_PERCPU_HASH) goto error; break; case BPF_FUNC_sk_storage_get: case BPF_FUNC_sk_storage_delete: if (map->map_type != BPF_MAP_TYPE_SK_STORAGE) goto error; break; case BPF_FUNC_inode_storage_get: case BPF_FUNC_inode_storage_delete: if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE) goto error; break; case BPF_FUNC_task_storage_get: case BPF_FUNC_task_storage_delete: if (map->map_type != BPF_MAP_TYPE_TASK_STORAGE) goto error; break; case BPF_FUNC_cgrp_storage_get: case BPF_FUNC_cgrp_storage_delete: if (map->map_type != BPF_MAP_TYPE_CGRP_STORAGE) goto error; break; default: break; } return 0; error: verbose(env, "cannot pass map_type %d into func %s#%d\n", map->map_type, func_id_name(func_id), func_id); return -EINVAL; } static bool check_raw_mode_ok(const struct bpf_func_proto *fn) { int count = 0; if (arg_type_is_raw_mem(fn->arg1_type)) count++; if (arg_type_is_raw_mem(fn->arg2_type)) count++; if (arg_type_is_raw_mem(fn->arg3_type)) count++; if (arg_type_is_raw_mem(fn->arg4_type)) count++; if (arg_type_is_raw_mem(fn->arg5_type)) count++; /* We only support one arg being in raw mode at the moment, * which is sufficient for the helper functions we have * right now. */ return count <= 1; } static bool check_args_pair_invalid(const struct bpf_func_proto *fn, int arg) { bool is_fixed = fn->arg_type[arg] & MEM_FIXED_SIZE; bool has_size = fn->arg_size[arg] != 0; bool is_next_size = false; if (arg + 1 < ARRAY_SIZE(fn->arg_type)) is_next_size = arg_type_is_mem_size(fn->arg_type[arg + 1]); if (base_type(fn->arg_type[arg]) != ARG_PTR_TO_MEM) return is_next_size; return has_size == is_next_size || is_next_size == is_fixed; } static bool check_arg_pair_ok(const struct bpf_func_proto *fn) { /* bpf_xxx(..., buf, len) call will access 'len' * bytes from memory 'buf'. Both arg types need * to be paired, so make sure there's no buggy * helper function specification. */ if (arg_type_is_mem_size(fn->arg1_type) || check_args_pair_invalid(fn, 0) || check_args_pair_invalid(fn, 1) || check_args_pair_invalid(fn, 2) || check_args_pair_invalid(fn, 3) || check_args_pair_invalid(fn, 4)) return false; return true; } static bool check_btf_id_ok(const struct bpf_func_proto *fn) { int i; for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) { if (base_type(fn->arg_type[i]) == ARG_PTR_TO_BTF_ID) return !!fn->arg_btf_id[i]; if (base_type(fn->arg_type[i]) == ARG_PTR_TO_SPIN_LOCK) return fn->arg_btf_id[i] == BPF_PTR_POISON; if (base_type(fn->arg_type[i]) != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i] && /* arg_btf_id and arg_size are in a union. */ (base_type(fn->arg_type[i]) != ARG_PTR_TO_MEM || !(fn->arg_type[i] & MEM_FIXED_SIZE))) return false; } return true; } static int check_func_proto(const struct bpf_func_proto *fn, int func_id) { return check_raw_mode_ok(fn) && check_arg_pair_ok(fn) && check_btf_id_ok(fn) ? 0 : -EINVAL; } /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END] * are now invalid, so turn them into unknown SCALAR_VALUE. * * This also applies to dynptr slices belonging to skb and xdp dynptrs, * since these slices point to packet data. */ static void clear_all_pkt_pointers(struct bpf_verifier_env *env) { struct bpf_func_state *state; struct bpf_reg_state *reg; bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({ if (reg_is_pkt_pointer_any(reg) || reg_is_dynptr_slice_pkt(reg)) mark_reg_invalid(env, reg); })); } enum { AT_PKT_END = -1, BEYOND_PKT_END = -2, }; static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range_open) { struct bpf_func_state *state = vstate->frame[vstate->curframe]; struct bpf_reg_state *reg = &state->regs[regn]; if (reg->type != PTR_TO_PACKET) /* PTR_TO_PACKET_META is not supported yet */ return; /* The 'reg' is pkt > pkt_end or pkt >= pkt_end. * How far beyond pkt_end it goes is unknown. * if (!range_open) it's the case of pkt >= pkt_end * if (range_open) it's the case of pkt > pkt_end * hence this pointer is at least 1 byte bigger than pkt_end */ if (range_open) reg->range = BEYOND_PKT_END; else reg->range = AT_PKT_END; } /* The pointer with the specified id has released its reference to kernel * resources. Identify all copies of the same pointer and clear the reference. */ static int release_reference(struct bpf_verifier_env *env, int ref_obj_id) { struct bpf_func_state *state; struct bpf_reg_state *reg; int err; err = release_reference_state(cur_func(env), ref_obj_id); if (err) return err; bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({ if (reg->ref_obj_id == ref_obj_id) mark_reg_invalid(env, reg); })); return 0; } static void invalidate_non_owning_refs(struct bpf_verifier_env *env) { struct bpf_func_state *unused; struct bpf_reg_state *reg; bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({ if (type_is_non_owning_ref(reg->type)) mark_reg_invalid(env, reg); })); } static void clear_caller_saved_regs(struct bpf_verifier_env *env, struct bpf_reg_state *regs) { int i; /* after the call registers r0 - r5 were scratched */ for (i = 0; i < CALLER_SAVED_REGS; i++) { mark_reg_not_init(env, regs, caller_saved[i]); __check_reg_arg(env, regs, caller_saved[i], DST_OP_NO_MARK); } } typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env, struct bpf_func_state *caller, struct bpf_func_state *callee, int insn_idx); static int set_callee_state(struct bpf_verifier_env *env, struct bpf_func_state *caller, struct bpf_func_state *callee, int insn_idx); static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int callsite, set_callee_state_fn set_callee_state_cb, struct bpf_verifier_state *state) { struct bpf_func_state *caller, *callee; int err; if (state->curframe + 1 >= MAX_CALL_FRAMES) { verbose(env, "the call stack of %d frames is too deep\n", state->curframe + 2); return -E2BIG; } if (state->frame[state->curframe + 1]) { verbose(env, "verifier bug. Frame %d already allocated\n", state->curframe + 1); return -EFAULT; } caller = state->frame[state->curframe]; callee = kzalloc(sizeof(*callee), GFP_KERNEL); if (!callee) return -ENOMEM; state->frame[state->curframe + 1] = callee; /* callee cannot access r0, r6 - r9 for reading and has to write * into its own stack before reading from it. * callee can read/write into caller's stack */ init_func_state(env, callee, /* remember the callsite, it will be used by bpf_exit */ callsite, state->curframe + 1 /* frameno within this callchain */, subprog /* subprog number within this prog */); /* Transfer references to the callee */ err = copy_reference_state(callee, caller); err = err ?: set_callee_state_cb(env, caller, callee, callsite); if (err) goto err_out; /* only increment it after check_reg_arg() finished */ state->curframe++; return 0; err_out: free_func_state(callee); state->frame[state->curframe + 1] = NULL; return err; } static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog, const struct btf *btf, struct bpf_reg_state *regs) { struct bpf_subprog_info *sub = subprog_info(env, subprog); struct bpf_verifier_log *log = &env->log; u32 i; int ret; ret = btf_prepare_func_args(env, subprog); if (ret) return ret; /* check that BTF function arguments match actual types that the * verifier sees. */ for (i = 0; i < sub->arg_cnt; i++) { u32 regno = i + 1; struct bpf_reg_state *reg = ®s[regno]; struct bpf_subprog_arg_info *arg = &sub->args[i]; if (arg->arg_type == ARG_ANYTHING) { if (reg->type != SCALAR_VALUE) { bpf_log(log, "R%d is not a scalar\n", regno); return -EINVAL; } } else if (arg->arg_type == ARG_PTR_TO_CTX) { ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE); if (ret < 0) return ret; /* If function expects ctx type in BTF check that caller * is passing PTR_TO_CTX. */ if (reg->type != PTR_TO_CTX) { bpf_log(log, "arg#%d expects pointer to ctx\n", i); return -EINVAL; } } else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) { ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE); if (ret < 0) return ret; if (check_mem_reg(env, reg, regno, arg->mem_size)) return -EINVAL; if (!(arg->arg_type & PTR_MAYBE_NULL) && (reg->type & PTR_MAYBE_NULL)) { bpf_log(log, "arg#%d is expected to be non-NULL\n", i); return -EINVAL; } } else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) { /* * Can pass any value and the kernel won't crash, but * only PTR_TO_ARENA or SCALAR make sense. Everything * else is a bug in the bpf program. Point it out to * the user at the verification time instead of * run-time debug nightmare. */ if (reg->type != PTR_TO_ARENA && reg->type != SCALAR_VALUE) { bpf_log(log, "R%d is not a pointer to arena or scalar.\n", regno); return -EINVAL; } } else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) { ret = check_func_arg_reg_off(env, reg, regno, ARG_PTR_TO_DYNPTR); if (ret) return ret; ret = process_dynptr_func(env, regno, -1, arg->arg_type, 0); if (ret) return ret; } else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) { struct bpf_call_arg_meta meta; int err; if (register_is_null(reg) && type_may_be_null(arg->arg_type)) continue; memset(&meta, 0, sizeof(meta)); /* leave func_id as zero */ err = check_reg_type(env, regno, arg->arg_type, &arg->btf_id, &meta); err = err ?: check_func_arg_reg_off(env, reg, regno, arg->arg_type); if (err) return err; } else { bpf_log(log, "verifier bug: unrecognized arg#%d type %d\n", i, arg->arg_type); return -EFAULT; } } return 0; } /* Compare BTF of a function call with given bpf_reg_state. * Returns: * EFAULT - there is a verifier bug. Abort verification. * EINVAL - there is a type mismatch or BTF is not available. * 0 - BTF matches with what bpf_reg_state expects. * Only PTR_TO_CTX and SCALAR_VALUE states are recognized. */ static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, struct bpf_reg_state *regs) { struct bpf_prog *prog = env->prog; struct btf *btf = prog->aux->btf; u32 btf_id; int err; if (!prog->aux->func_info) return -EINVAL; btf_id = prog->aux->func_info[subprog].type_id; if (!btf_id) return -EFAULT; if (prog->aux->func_info_aux[subprog].unreliable) return -EINVAL; err = btf_check_func_arg_match(env, subprog, btf, regs); /* Compiler optimizations can remove arguments from static functions * or mismatched type can be passed into a global function. * In such cases mark the function as unreliable from BTF point of view. */ if (err) prog->aux->func_info_aux[subprog].unreliable = true; return err; } static int push_callback_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int insn_idx, int subprog, set_callee_state_fn set_callee_state_cb) { struct bpf_verifier_state *state = env->cur_state, *callback_state; struct bpf_func_state *caller, *callee; int err; caller = state->frame[state->curframe]; err = btf_check_subprog_call(env, subprog, caller->regs); if (err == -EFAULT) return err; /* set_callee_state is used for direct subprog calls, but we are * interested in validating only BPF helpers that can call subprogs as * callbacks */ env->subprog_info[subprog].is_cb = true; if (bpf_pseudo_kfunc_call(insn) && !is_callback_calling_kfunc(insn->imm)) { verbose(env, "verifier bug: kfunc %s#%d not marked as callback-calling\n", func_id_name(insn->imm), insn->imm); return -EFAULT; } else if (!bpf_pseudo_kfunc_call(insn) && !is_callback_calling_function(insn->imm)) { /* helper */ verbose(env, "verifier bug: helper %s#%d not marked as callback-calling\n", func_id_name(insn->imm), insn->imm); return -EFAULT; } if (is_async_callback_calling_insn(insn)) { struct bpf_verifier_state *async_cb; /* there is no real recursion here. timer and workqueue callbacks are async */ env->subprog_info[subprog].is_async_cb = true; async_cb = push_async_cb(env, env->subprog_info[subprog].start, insn_idx, subprog, is_bpf_wq_set_callback_impl_kfunc(insn->imm)); if (!async_cb) return -EFAULT; callee = async_cb->frame[0]; callee->async_entry_cnt = caller->async_entry_cnt + 1; /* Convert bpf_timer_set_callback() args into timer callback args */ err = set_callee_state_cb(env, caller, callee, insn_idx); if (err) return err; return 0; } /* for callback functions enqueue entry to callback and * proceed with next instruction within current frame. */ callback_state = push_stack(env, env->subprog_info[subprog].start, insn_idx, false); if (!callback_state) return -ENOMEM; err = setup_func_entry(env, subprog, insn_idx, set_callee_state_cb, callback_state); if (err) return err; callback_state->callback_unroll_depth++; callback_state->frame[callback_state->curframe - 1]->callback_depth++; caller->callback_depth = 0; return 0; } static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx) { struct bpf_verifier_state *state = env->cur_state; struct bpf_func_state *caller; int err, subprog, target_insn; target_insn = *insn_idx + insn->imm + 1; subprog = find_subprog(env, target_insn); if (subprog < 0) { verbose(env, "verifier bug. No program starts at insn %d\n", target_insn); return -EFAULT; } caller = state->frame[state->curframe]; err = btf_check_subprog_call(env, subprog, caller->regs); if (err == -EFAULT) return err; if (subprog_is_global(env, subprog)) { const char *sub_name = subprog_name(env, subprog); /* Only global subprogs cannot be called with a lock held. */ if (cur_func(env)->active_locks) { verbose(env, "global function calls are not allowed while holding a lock,\n" "use static function instead\n"); return -EINVAL; } /* Only global subprogs cannot be called with preemption disabled. */ if (env->cur_state->active_preempt_lock) { verbose(env, "global function calls are not allowed with preemption disabled,\n" "use static function instead\n"); return -EINVAL; } if (err) { verbose(env, "Caller passes invalid args into func#%d ('%s')\n", subprog, sub_name); return err; } verbose(env, "Func#%d ('%s') is global and assumed valid.\n", subprog, sub_name); if (env->subprog_info[subprog].changes_pkt_data) clear_all_pkt_pointers(env); /* mark global subprog for verifying after main prog */ subprog_aux(env, subprog)->called = true; clear_caller_saved_regs(env, caller->regs); /* All global functions return a 64-bit SCALAR_VALUE */ mark_reg_unknown(env, caller->regs, BPF_REG_0); caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG; /* continue with next insn after call */ return 0; } /* for regular function entry setup new frame and continue * from that frame. */ err = setup_func_entry(env, subprog, *insn_idx, set_callee_state, state); if (err) return err; clear_caller_saved_regs(env, caller->regs); /* and go analyze first insn of the callee */ *insn_idx = env->subprog_info[subprog].start - 1; if (env->log.level & BPF_LOG_LEVEL) { verbose(env, "caller:\n"); print_verifier_state(env, caller, true); verbose(env, "callee:\n"); print_verifier_state(env, state->frame[state->curframe], true); } return 0; } int map_set_for_each_callback_args(struct bpf_verifier_env *env, struct bpf_func_state *caller, struct bpf_func_state *callee) { /* bpf_for_each_map_elem(struct bpf_map *map, void *callback_fn, * void *callback_ctx, u64 flags); * callback_fn(struct bpf_map *map, void *key, void *value, * void *callback_ctx); */ callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1]; callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY; __mark_reg_known_zero(&callee->regs[BPF_REG_2]); callee->regs[BPF_REG_2].map_ptr = caller->regs[BPF_REG_1].map_ptr; callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE; __mark_reg_known_zero(&callee->regs[BPF_REG_3]); callee->regs[BPF_REG_3].map_ptr = caller->regs[BPF_REG_1].map_ptr; /* pointer to stack or null */ callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3]; /* unused */ __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); return 0; } static int set_callee_state(struct bpf_verifier_env *env, struct bpf_func_state *caller, struct bpf_func_state *callee, int insn_idx) { int i; /* copy r1 - r5 args that callee can access. The copy includes parent * pointers, which connects us up to the liveness chain */ for (i = BPF_REG_1; i <= BPF_REG_5; i++) callee->regs[i] = caller->regs[i]; return 0; } static int set_map_elem_callback_state(struct bpf_verifier_env *env, struct bpf_func_state *caller, struct bpf_func_state *callee, int insn_idx) { struct bpf_insn_aux_data *insn_aux = &env->insn_aux_data[insn_idx]; struct bpf_map *map; int err; /* valid map_ptr and poison value does not matter */ map = insn_aux->map_ptr_state.map_ptr; if (!map->ops->map_set_for_each_callback_args || !map->ops->map_for_each_callback) { verbose(env, "callback function not allowed for map\n"); return -ENOTSUPP; } err = map->ops->map_set_for_each_callback_args(env, caller, callee); if (err) return err; callee->in_callback_fn = true; callee->callback_ret_range = retval_range(0, 1); return 0; } static int set_loop_callback_state(struct bpf_verifier_env *env, struct bpf_func_state *caller, struct bpf_func_state *callee, int insn_idx) { /* bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx, * u64 flags); * callback_fn(u64 index, void *callback_ctx); */ callee->regs[BPF_REG_1].type = SCALAR_VALUE; callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3]; /* unused */ __mark_reg_not_init(env, &callee->regs[BPF_REG_3]); __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; callee->callback_ret_range = retval_range(0, 1); return 0; } static int set_timer_callback_state(struct bpf_verifier_env *env, struct bpf_func_state *caller, struct bpf_func_state *callee, int insn_idx) { struct bpf_map *map_ptr = caller->regs[BPF_REG_1].map_ptr; /* bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn); * callback_fn(struct bpf_map *map, void *key, void *value); */ callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP; __mark_reg_known_zero(&callee->regs[BPF_REG_1]); callee->regs[BPF_REG_1].map_ptr = map_ptr; callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY; __mark_reg_known_zero(&callee->regs[BPF_REG_2]); callee->regs[BPF_REG_2].map_ptr = map_ptr; callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE; __mark_reg_known_zero(&callee->regs[BPF_REG_3]); callee->regs[BPF_REG_3].map_ptr = map_ptr; /* unused */ __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_async_callback_fn = true; callee->callback_ret_range = retval_range(0, 1); return 0; } static int set_find_vma_callback_state(struct bpf_verifier_env *env, struct bpf_func_state *caller, struct bpf_func_state *callee, int insn_idx) { /* bpf_find_vma(struct task_struct *task, u64 addr, * void *callback_fn, void *callback_ctx, u64 flags) * (callback_fn)(struct task_struct *task, * struct vm_area_struct *vma, void *callback_ctx); */ callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1]; callee->regs[BPF_REG_2].type = PTR_TO_BTF_ID; __mark_reg_known_zero(&callee->regs[BPF_REG_2]); callee->regs[BPF_REG_2].btf = btf_vmlinux; callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA]; /* pointer to stack or null */ callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4]; /* unused */ __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; callee->callback_ret_range = retval_range(0, 1); return 0; } static int set_user_ringbuf_callback_state(struct bpf_verifier_env *env, struct bpf_func_state *caller, struct bpf_func_state *callee, int insn_idx) { /* bpf_user_ringbuf_drain(struct bpf_map *map, void *callback_fn, void * callback_ctx, u64 flags); * callback_fn(const struct bpf_dynptr_t* dynptr, void *callback_ctx); */ __mark_reg_not_init(env, &callee->regs[BPF_REG_0]); mark_dynptr_cb_reg(env, &callee->regs[BPF_REG_1], BPF_DYNPTR_TYPE_LOCAL); callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3]; /* unused */ __mark_reg_not_init(env, &callee->regs[BPF_REG_3]); __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; callee->callback_ret_range = retval_range(0, 1); return 0; } static int set_rbtree_add_callback_state(struct bpf_verifier_env *env, struct bpf_func_state *caller, struct bpf_func_state *callee, int insn_idx) { /* void bpf_rbtree_add_impl(struct bpf_rb_root *root, struct bpf_rb_node *node, * bool (less)(struct bpf_rb_node *a, const struct bpf_rb_node *b)); * * 'struct bpf_rb_node *node' arg to bpf_rbtree_add_impl is the same PTR_TO_BTF_ID w/ offset * that 'less' callback args will be receiving. However, 'node' arg was release_reference'd * by this point, so look at 'root' */ struct btf_field *field; field = reg_find_field_offset(&caller->regs[BPF_REG_1], caller->regs[BPF_REG_1].off, BPF_RB_ROOT); if (!field || !field->graph_root.value_btf_id) return -EFAULT; mark_reg_graph_node(callee->regs, BPF_REG_1, &field->graph_root); ref_set_non_owning(env, &callee->regs[BPF_REG_1]); mark_reg_graph_node(callee->regs, BPF_REG_2, &field->graph_root); ref_set_non_owning(env, &callee->regs[BPF_REG_2]); __mark_reg_not_init(env, &callee->regs[BPF_REG_3]); __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; callee->callback_ret_range = retval_range(0, 1); return 0; } static bool is_rbtree_lock_required_kfunc(u32 btf_id); /* Are we currently verifying the callback for a rbtree helper that must * be called with lock held? If so, no need to complain about unreleased * lock */ static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env) { struct bpf_verifier_state *state = env->cur_state; struct bpf_insn *insn = env->prog->insnsi; struct bpf_func_state *callee; int kfunc_btf_id; if (!state->curframe) return false; callee = state->frame[state->curframe]; if (!callee->in_callback_fn) return false; kfunc_btf_id = insn[callee->callsite].imm; return is_rbtree_lock_required_kfunc(kfunc_btf_id); } static bool retval_range_within(struct bpf_retval_range range, const struct bpf_reg_state *reg, bool return_32bit) { if (return_32bit) return range.minval <= reg->s32_min_value && reg->s32_max_value <= range.maxval; else return range.minval <= reg->smin_value && reg->smax_value <= range.maxval; } static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) { struct bpf_verifier_state *state = env->cur_state, *prev_st; struct bpf_func_state *caller, *callee; struct bpf_reg_state *r0; bool in_callback_fn; int err; callee = state->frame[state->curframe]; r0 = &callee->regs[BPF_REG_0]; if (r0->type == PTR_TO_STACK) { /* technically it's ok to return caller's stack pointer * (or caller's caller's pointer) back to the caller, * since these pointers are valid. Only current stack * pointer will be invalid as soon as function exits, * but let's be conservative */ verbose(env, "cannot return stack pointer to the caller\n"); return -EINVAL; } caller = state->frame[state->curframe - 1]; if (callee->in_callback_fn) { if (r0->type != SCALAR_VALUE) { verbose(env, "R0 not a scalar value\n"); return -EACCES; } /* we are going to rely on register's precise value */ err = mark_reg_read(env, r0, r0->parent, REG_LIVE_READ64); err = err ?: mark_chain_precision(env, BPF_REG_0); if (err) return err; /* enforce R0 return value range, and bpf_callback_t returns 64bit */ if (!retval_range_within(callee->callback_ret_range, r0, false)) { verbose_invalid_scalar(env, r0, callee->callback_ret_range, "At callback return", "R0"); return -EINVAL; } if (!calls_callback(env, callee->callsite)) { verbose(env, "BUG: in callback at %d, callsite %d !calls_callback\n", *insn_idx, callee->callsite); return -EFAULT; } } else { /* return to the caller whatever r0 had in the callee */ caller->regs[BPF_REG_0] = *r0; } /* Transfer references to the caller */ err = copy_reference_state(caller, callee); if (err) return err; /* for callbacks like bpf_loop or bpf_for_each_map_elem go back to callsite, * there function call logic would reschedule callback visit. If iteration * converges is_state_visited() would prune that visit eventually. */ in_callback_fn = callee->in_callback_fn; if (in_callback_fn) *insn_idx = callee->callsite; else *insn_idx = callee->callsite + 1; if (env->log.level & BPF_LOG_LEVEL) { verbose(env, "returning from callee:\n"); print_verifier_state(env, callee, true); verbose(env, "to caller at %d:\n", *insn_idx); print_verifier_state(env, caller, true); } /* clear everything in the callee. In case of exceptional exits using * bpf_throw, this will be done by copy_verifier_state for extra frames. */ free_func_state(callee); state->frame[state->curframe--] = NULL; /* for callbacks widen imprecise scalars to make programs like below verify: * * struct ctx { int i; } * void cb(int idx, struct ctx *ctx) { ctx->i++; ... } * ... * struct ctx = { .i = 0; } * bpf_loop(100, cb, &ctx, 0); * * This is similar to what is done in process_iter_next_call() for open * coded iterators. */ prev_st = in_callback_fn ? find_prev_entry(env, state, *insn_idx) : NULL; if (prev_st) { err = widen_imprecise_scalars(env, prev_st, state); if (err) return err; } return 0; } static int do_refine_retval_range(struct bpf_verifier_env *env, struct bpf_reg_state *regs, int ret_type, int func_id, struct bpf_call_arg_meta *meta) { struct bpf_reg_state *ret_reg = ®s[BPF_REG_0]; if (ret_type != RET_INTEGER) return 0; switch (func_id) { case BPF_FUNC_get_stack: case BPF_FUNC_get_task_stack: case BPF_FUNC_probe_read_str: case BPF_FUNC_probe_read_kernel_str: case BPF_FUNC_probe_read_user_str: ret_reg->smax_value = meta->msize_max_value; ret_reg->s32_max_value = meta->msize_max_value; ret_reg->smin_value = -MAX_ERRNO; ret_reg->s32_min_value = -MAX_ERRNO; reg_bounds_sync(ret_reg); break; case BPF_FUNC_get_smp_processor_id: ret_reg->umax_value = nr_cpu_ids - 1; ret_reg->u32_max_value = nr_cpu_ids - 1; ret_reg->smax_value = nr_cpu_ids - 1; ret_reg->s32_max_value = nr_cpu_ids - 1; ret_reg->umin_value = 0; ret_reg->u32_min_value = 0; ret_reg->smin_value = 0; ret_reg->s32_min_value = 0; reg_bounds_sync(ret_reg); break; } return reg_bounds_sanity_check(env, ret_reg, "retval"); } static int record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, int func_id, int insn_idx) { struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx]; struct bpf_map *map = meta->map_ptr; if (func_id != BPF_FUNC_tail_call && func_id != BPF_FUNC_map_lookup_elem && func_id != BPF_FUNC_map_update_elem && func_id != BPF_FUNC_map_delete_elem && func_id != BPF_FUNC_map_push_elem && func_id != BPF_FUNC_map_pop_elem && func_id != BPF_FUNC_map_peek_elem && func_id != BPF_FUNC_for_each_map_elem && func_id != BPF_FUNC_redirect_map && func_id != BPF_FUNC_map_lookup_percpu_elem) return 0; if (map == NULL) { verbose(env, "kernel subsystem misconfigured verifier\n"); return -EINVAL; } /* In case of read-only, some additional restrictions * need to be applied in order to prevent altering the * state of the map from program side. */ if ((map->map_flags & BPF_F_RDONLY_PROG) && (func_id == BPF_FUNC_map_delete_elem || func_id == BPF_FUNC_map_update_elem || func_id == BPF_FUNC_map_push_elem || func_id == BPF_FUNC_map_pop_elem)) { verbose(env, "write into map forbidden\n"); return -EACCES; } if (!aux->map_ptr_state.map_ptr) bpf_map_ptr_store(aux, meta->map_ptr, !meta->map_ptr->bypass_spec_v1, false); else if (aux->map_ptr_state.map_ptr != meta->map_ptr) bpf_map_ptr_store(aux, meta->map_ptr, !meta->map_ptr->bypass_spec_v1, true); return 0; } static int record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, int func_id, int insn_idx) { struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx]; struct bpf_reg_state *regs = cur_regs(env), *reg; struct bpf_map *map = meta->map_ptr; u64 val, max; int err; if (func_id != BPF_FUNC_tail_call) return 0; if (!map || map->map_type != BPF_MAP_TYPE_PROG_ARRAY) { verbose(env, "kernel subsystem misconfigured verifier\n"); return -EINVAL; } reg = ®s[BPF_REG_3]; val = reg->var_off.value; max = map->max_entries; if (!(is_reg_const(reg, false) && val < max)) { bpf_map_key_store(aux, BPF_MAP_KEY_POISON); return 0; } err = mark_chain_precision(env, BPF_REG_3); if (err) return err; if (bpf_map_key_unseen(aux)) bpf_map_key_store(aux, val); else if (!bpf_map_key_poisoned(aux) && bpf_map_key_immediate(aux) != val) bpf_map_key_store(aux, BPF_MAP_KEY_POISON); return 0; } static int check_reference_leak(struct bpf_verifier_env *env, bool exception_exit) { struct bpf_func_state *state = cur_func(env); bool refs_lingering = false; int i; if (!exception_exit && state->frameno) return 0; for (i = 0; i < state->acquired_refs; i++) { if (state->refs[i].type != REF_TYPE_PTR) continue; verbose(env, "Unreleased reference id=%d alloc_insn=%d\n", state->refs[i].id, state->refs[i].insn_idx); refs_lingering = true; } return refs_lingering ? -EINVAL : 0; } static int check_resource_leak(struct bpf_verifier_env *env, bool exception_exit, bool check_lock, const char *prefix) { int err; if (check_lock && cur_func(env)->active_locks) { verbose(env, "%s cannot be used inside bpf_spin_lock-ed region\n", prefix); return -EINVAL; } err = check_reference_leak(env, exception_exit); if (err) { verbose(env, "%s would lead to reference leak\n", prefix); return err; } if (check_lock && env->cur_state->active_rcu_lock) { verbose(env, "%s cannot be used inside bpf_rcu_read_lock-ed region\n", prefix); return -EINVAL; } if (check_lock && env->cur_state->active_preempt_lock) { verbose(env, "%s cannot be used inside bpf_preempt_disable-ed region\n", prefix); return -EINVAL; } return 0; } static int check_bpf_snprintf_call(struct bpf_verifier_env *env, struct bpf_reg_state *regs) { struct bpf_reg_state *fmt_reg = ®s[BPF_REG_3]; struct bpf_reg_state *data_len_reg = ®s[BPF_REG_5]; struct bpf_map *fmt_map = fmt_reg->map_ptr; struct bpf_bprintf_data data = {}; int err, fmt_map_off, num_args; u64 fmt_addr; char *fmt; /* data must be an array of u64 */ if (data_len_reg->var_off.value % 8) return -EINVAL; num_args = data_len_reg->var_off.value / 8; /* fmt being ARG_PTR_TO_CONST_STR guarantees that var_off is const * and map_direct_value_addr is set. */ fmt_map_off = fmt_reg->off + fmt_reg->var_off.value; err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr, fmt_map_off); if (err) { verbose(env, "verifier bug\n"); return -EFAULT; } fmt = (char *)(long)fmt_addr + fmt_map_off; /* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we * can focus on validating the format specifiers. */ err = bpf_bprintf_prepare(fmt, UINT_MAX, NULL, num_args, &data); if (err < 0) verbose(env, "Invalid format string\n"); return err; } static int check_get_func_ip(struct bpf_verifier_env *env) { enum bpf_prog_type type = resolve_prog_type(env->prog); int func_id = BPF_FUNC_get_func_ip; if (type == BPF_PROG_TYPE_TRACING) { if (!bpf_prog_has_trampoline(env->prog)) { verbose(env, "func %s#%d supported only for fentry/fexit/fmod_ret programs\n", func_id_name(func_id), func_id); return -ENOTSUPP; } return 0; } else if (type == BPF_PROG_TYPE_KPROBE) { return 0; } verbose(env, "func %s#%d not supported for program type %d\n", func_id_name(func_id), func_id, type); return -ENOTSUPP; } static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env) { return &env->insn_aux_data[env->insn_idx]; } static bool loop_flag_is_zero(struct bpf_verifier_env *env) { struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *reg = ®s[BPF_REG_4]; bool reg_is_null = register_is_null(reg); if (reg_is_null) mark_chain_precision(env, BPF_REG_4); return reg_is_null; } static void update_loop_inline_state(struct bpf_verifier_env *env, u32 subprogno) { struct bpf_loop_inline_state *state = &cur_aux(env)->loop_inline_state; if (!state->initialized) { state->initialized = 1; state->fit_for_inline = loop_flag_is_zero(env); state->callback_subprogno = subprogno; return; } if (!state->fit_for_inline) return; state->fit_for_inline = (loop_flag_is_zero(env) && state->callback_subprogno == subprogno); } static int get_helper_proto(struct bpf_verifier_env *env, int func_id, const struct bpf_func_proto **ptr) { if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) return -ERANGE; if (!env->ops->get_func_proto) return -EINVAL; *ptr = env->ops->get_func_proto(func_id, env->prog); return *ptr ? 0 : -EINVAL; } static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx_p) { enum bpf_prog_type prog_type = resolve_prog_type(env->prog); bool returns_cpu_specific_alloc_ptr = false; const struct bpf_func_proto *fn = NULL; enum bpf_return_type ret_type; enum bpf_type_flag ret_flag; struct bpf_reg_state *regs; struct bpf_call_arg_meta meta; int insn_idx = *insn_idx_p; bool changes_data; int i, err, func_id; /* find function prototype */ func_id = insn->imm; err = get_helper_proto(env, insn->imm, &fn); if (err == -ERANGE) { verbose(env, "invalid func %s#%d\n", func_id_name(func_id), func_id); return -EINVAL; } if (err) { verbose(env, "program of this type cannot use helper %s#%d\n", func_id_name(func_id), func_id); return err; } /* eBPF programs must be GPL compatible to use GPL-ed functions */ if (!env->prog->gpl_compatible && fn->gpl_only) { verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n"); return -EINVAL; } if (fn->allowed && !fn->allowed(env->prog)) { verbose(env, "helper call is not allowed in probe\n"); return -EINVAL; } if (!in_sleepable(env) && fn->might_sleep) { verbose(env, "helper call might sleep in a non-sleepable prog\n"); return -EINVAL; } /* With LD_ABS/IND some JITs save/restore skb from r1. */ changes_data = bpf_helper_changes_pkt_data(func_id); if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) { verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n", func_id_name(func_id), func_id); return -EINVAL; } memset(&meta, 0, sizeof(meta)); meta.pkt_access = fn->pkt_access; err = check_func_proto(fn, func_id); if (err) { verbose(env, "kernel subsystem misconfigured func %s#%d\n", func_id_name(func_id), func_id); return err; } if (env->cur_state->active_rcu_lock) { if (fn->might_sleep) { verbose(env, "sleepable helper %s#%d in rcu_read_lock region\n", func_id_name(func_id), func_id); return -EINVAL; } if (in_sleepable(env) && is_storage_get_function(func_id)) env->insn_aux_data[insn_idx].storage_get_func_atomic = true; } if (env->cur_state->active_preempt_lock) { if (fn->might_sleep) { verbose(env, "sleepable helper %s#%d in non-preemptible region\n", func_id_name(func_id), func_id); return -EINVAL; } if (in_sleepable(env) && is_storage_get_function(func_id)) env->insn_aux_data[insn_idx].storage_get_func_atomic = true; } meta.func_id = func_id; /* check args */ for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) { err = check_func_arg(env, i, &meta, fn, insn_idx); if (err) return err; } err = record_func_map(env, &meta, func_id, insn_idx); if (err) return err; err = record_func_key(env, &meta, func_id, insn_idx); if (err) return err; /* Mark slots with STACK_MISC in case of raw mode, stack offset * is inferred from register state. */ for (i = 0; i < meta.access_size; i++) { err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1, false, false); if (err) return err; } regs = cur_regs(env); if (meta.release_regno) { err = -EINVAL; /* This can only be set for PTR_TO_STACK, as CONST_PTR_TO_DYNPTR cannot * be released by any dynptr helper. Hence, unmark_stack_slots_dynptr * is safe to do directly. */ if (arg_type_is_dynptr(fn->arg_type[meta.release_regno - BPF_REG_1])) { if (regs[meta.release_regno].type == CONST_PTR_TO_DYNPTR) { verbose(env, "verifier internal error: CONST_PTR_TO_DYNPTR cannot be released\n"); return -EFAULT; } err = unmark_stack_slots_dynptr(env, ®s[meta.release_regno]); } else if (func_id == BPF_FUNC_kptr_xchg && meta.ref_obj_id) { u32 ref_obj_id = meta.ref_obj_id; bool in_rcu = in_rcu_cs(env); struct bpf_func_state *state; struct bpf_reg_state *reg; err = release_reference_state(cur_func(env), ref_obj_id); if (!err) { bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({ if (reg->ref_obj_id == ref_obj_id) { if (in_rcu && (reg->type & MEM_ALLOC) && (reg->type & MEM_PERCPU)) { reg->ref_obj_id = 0; reg->type &= ~MEM_ALLOC; reg->type |= MEM_RCU; } else { mark_reg_invalid(env, reg); } } })); } } else if (meta.ref_obj_id) { err = release_reference(env, meta.ref_obj_id); } else if (register_is_null(®s[meta.release_regno])) { /* meta.ref_obj_id can only be 0 if register that is meant to be * released is NULL, which must be > R0. */ err = 0; } if (err) { verbose(env, "func %s#%d reference has not been acquired before\n", func_id_name(func_id), func_id); return err; } } switch (func_id) { case BPF_FUNC_tail_call: err = check_resource_leak(env, false, true, "tail_call"); if (err) return err; break; case BPF_FUNC_get_local_storage: /* check that flags argument in get_local_storage(map, flags) is 0, * this is required because get_local_storage() can't return an error. */ if (!register_is_null(®s[BPF_REG_2])) { verbose(env, "get_local_storage() doesn't support non-zero flags\n"); return -EINVAL; } break; case BPF_FUNC_for_each_map_elem: err = push_callback_call(env, insn, insn_idx, meta.subprogno, set_map_elem_callback_state); break; case BPF_FUNC_timer_set_callback: err = push_callback_call(env, insn, insn_idx, meta.subprogno, set_timer_callback_state); break; case BPF_FUNC_find_vma: err = push_callback_call(env, insn, insn_idx, meta.subprogno, set_find_vma_callback_state); break; case BPF_FUNC_snprintf: err = check_bpf_snprintf_call(env, regs); break; case BPF_FUNC_loop: update_loop_inline_state(env, meta.subprogno); /* Verifier relies on R1 value to determine if bpf_loop() iteration * is finished, thus mark it precise. */ err = mark_chain_precision(env, BPF_REG_1); if (err) return err; if (cur_func(env)->callback_depth < regs[BPF_REG_1].umax_value) { err = push_callback_call(env, insn, insn_idx, meta.subprogno, set_loop_callback_state); } else { cur_func(env)->callback_depth = 0; if (env->log.level & BPF_LOG_LEVEL2) verbose(env, "frame%d bpf_loop iteration limit reached\n", env->cur_state->curframe); } break; case BPF_FUNC_dynptr_from_mem: if (regs[BPF_REG_1].type != PTR_TO_MAP_VALUE) { verbose(env, "Unsupported reg type %s for bpf_dynptr_from_mem data\n", reg_type_str(env, regs[BPF_REG_1].type)); return -EACCES; } break; case BPF_FUNC_set_retval: if (prog_type == BPF_PROG_TYPE_LSM && env->prog->expected_attach_type == BPF_LSM_CGROUP) { if (!env->prog->aux->attach_func_proto->type) { /* Make sure programs that attach to void * hooks don't try to modify return value. */ verbose(env, "BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n"); return -EINVAL; } } break; case BPF_FUNC_dynptr_data: { struct bpf_reg_state *reg; int id, ref_obj_id; reg = get_dynptr_arg_reg(env, fn, regs); if (!reg) return -EFAULT; if (meta.dynptr_id) { verbose(env, "verifier internal error: meta.dynptr_id already set\n"); return -EFAULT; } if (meta.ref_obj_id) { verbose(env, "verifier internal error: meta.ref_obj_id already set\n"); return -EFAULT; } id = dynptr_id(env, reg); if (id < 0) { verbose(env, "verifier internal error: failed to obtain dynptr id\n"); return id; } ref_obj_id = dynptr_ref_obj_id(env, reg); if (ref_obj_id < 0) { verbose(env, "verifier internal error: failed to obtain dynptr ref_obj_id\n"); return ref_obj_id; } meta.dynptr_id = id; meta.ref_obj_id = ref_obj_id; break; } case BPF_FUNC_dynptr_write: { enum bpf_dynptr_type dynptr_type; struct bpf_reg_state *reg; reg = get_dynptr_arg_reg(env, fn, regs); if (!reg) return -EFAULT; dynptr_type = dynptr_get_type(env, reg); if (dynptr_type == BPF_DYNPTR_TYPE_INVALID) return -EFAULT; if (dynptr_type == BPF_DYNPTR_TYPE_SKB) /* this will trigger clear_all_pkt_pointers(), which will * invalidate all dynptr slices associated with the skb */ changes_data = true; break; } case BPF_FUNC_per_cpu_ptr: case BPF_FUNC_this_cpu_ptr: { struct bpf_reg_state *reg = ®s[BPF_REG_1]; const struct btf_type *type; if (reg->type & MEM_RCU) { type = btf_type_by_id(reg->btf, reg->btf_id); if (!type || !btf_type_is_struct(type)) { verbose(env, "Helper has invalid btf/btf_id in R1\n"); return -EFAULT; } returns_cpu_specific_alloc_ptr = true; env->insn_aux_data[insn_idx].call_with_percpu_alloc_ptr = true; } break; } case BPF_FUNC_user_ringbuf_drain: err = push_callback_call(env, insn, insn_idx, meta.subprogno, set_user_ringbuf_callback_state); break; } if (err) return err; /* reset caller saved regs */ for (i = 0; i < CALLER_SAVED_REGS; i++) { mark_reg_not_init(env, regs, caller_saved[i]); check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); } /* helper call returns 64-bit value. */ regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG; /* update return register (already marked as written above) */ ret_type = fn->ret_type; ret_flag = type_flag(ret_type); switch (base_type(ret_type)) { case RET_INTEGER: /* sets type to SCALAR_VALUE */ mark_reg_unknown(env, regs, BPF_REG_0); break; case RET_VOID: regs[BPF_REG_0].type = NOT_INIT; break; case RET_PTR_TO_MAP_VALUE: /* There is no offset yet applied, variable or fixed */ mark_reg_known_zero(env, regs, BPF_REG_0); /* remember map_ptr, so that check_map_access() * can check 'value_size' boundary of memory access * to map element returned from bpf_map_lookup_elem() */ if (meta.map_ptr == NULL) { verbose(env, "kernel subsystem misconfigured verifier\n"); return -EINVAL; } regs[BPF_REG_0].map_ptr = meta.map_ptr; regs[BPF_REG_0].map_uid = meta.map_uid; regs[BPF_REG_0].type = PTR_TO_MAP_VALUE | ret_flag; if (!type_may_be_null(ret_type) && btf_record_has_field(meta.map_ptr->record, BPF_SPIN_LOCK)) { regs[BPF_REG_0].id = ++env->id_gen; } break; case RET_PTR_TO_SOCKET: mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_SOCKET | ret_flag; break; case RET_PTR_TO_SOCK_COMMON: mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON | ret_flag; break; case RET_PTR_TO_TCP_SOCK: mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_TCP_SOCK | ret_flag; break; case RET_PTR_TO_MEM: mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag; regs[BPF_REG_0].mem_size = meta.mem_size; break; case RET_PTR_TO_MEM_OR_BTF_ID: { const struct btf_type *t; mark_reg_known_zero(env, regs, BPF_REG_0); t = btf_type_skip_modifiers(meta.ret_btf, meta.ret_btf_id, NULL); if (!btf_type_is_struct(t)) { u32 tsize; const struct btf_type *ret; const char *tname; /* resolve the type size of ksym. */ ret = btf_resolve_size(meta.ret_btf, t, &tsize); if (IS_ERR(ret)) { tname = btf_name_by_offset(meta.ret_btf, t->name_off); verbose(env, "unable to resolve the size of type '%s': %ld\n", tname, PTR_ERR(ret)); return -EINVAL; } regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag; regs[BPF_REG_0].mem_size = tsize; } else { if (returns_cpu_specific_alloc_ptr) { regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC | MEM_RCU; } else { /* MEM_RDONLY may be carried from ret_flag, but it * doesn't apply on PTR_TO_BTF_ID. Fold it, otherwise * it will confuse the check of PTR_TO_BTF_ID in * check_mem_access(). */ ret_flag &= ~MEM_RDONLY; regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag; } regs[BPF_REG_0].btf = meta.ret_btf; regs[BPF_REG_0].btf_id = meta.ret_btf_id; } break; } case RET_PTR_TO_BTF_ID: { struct btf *ret_btf; int ret_btf_id; mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag; if (func_id == BPF_FUNC_kptr_xchg) { ret_btf = meta.kptr_field->kptr.btf; ret_btf_id = meta.kptr_field->kptr.btf_id; if (!btf_is_kernel(ret_btf)) { regs[BPF_REG_0].type |= MEM_ALLOC; if (meta.kptr_field->type == BPF_KPTR_PERCPU) regs[BPF_REG_0].type |= MEM_PERCPU; } } else { if (fn->ret_btf_id == BPF_PTR_POISON) { verbose(env, "verifier internal error:"); verbose(env, "func %s has non-overwritten BPF_PTR_POISON return type\n", func_id_name(func_id)); return -EINVAL; } ret_btf = btf_vmlinux; ret_btf_id = *fn->ret_btf_id; } if (ret_btf_id == 0) { verbose(env, "invalid return type %u of func %s#%d\n", base_type(ret_type), func_id_name(func_id), func_id); return -EINVAL; } regs[BPF_REG_0].btf = ret_btf; regs[BPF_REG_0].btf_id = ret_btf_id; break; } default: verbose(env, "unknown return type %u of func %s#%d\n", base_type(ret_type), func_id_name(func_id), func_id); return -EINVAL; } if (type_may_be_null(regs[BPF_REG_0].type)) regs[BPF_REG_0].id = ++env->id_gen; if (helper_multiple_ref_obj_use(func_id, meta.map_ptr)) { verbose(env, "verifier internal error: func %s#%d sets ref_obj_id more than once\n", func_id_name(func_id), func_id); return -EFAULT; } if (is_dynptr_ref_function(func_id)) regs[BPF_REG_0].dynptr_id = meta.dynptr_id; if (is_ptr_cast_function(func_id) || is_dynptr_ref_function(func_id)) { /* For release_reference() */ regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id; } else if (is_acquire_function(func_id, meta.map_ptr)) { int id = acquire_reference_state(env, insn_idx); if (id < 0) return id; /* For mark_ptr_or_null_reg() */ regs[BPF_REG_0].id = id; /* For release_reference() */ regs[BPF_REG_0].ref_obj_id = id; } err = do_refine_retval_range(env, regs, fn->ret_type, func_id, &meta); if (err) return err; err = check_map_func_compatibility(env, meta.map_ptr, func_id); if (err) return err; if ((func_id == BPF_FUNC_get_stack || func_id == BPF_FUNC_get_task_stack) && !env->prog->has_callchain_buf) { const char *err_str; #ifdef CONFIG_PERF_EVENTS err = get_callchain_buffers(sysctl_perf_event_max_stack); err_str = "cannot get callchain buffer for func %s#%d\n"; #else err = -ENOTSUPP; err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n"; #endif if (err) { verbose(env, err_str, func_id_name(func_id), func_id); return err; } env->prog->has_callchain_buf = true; } if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack) env->prog->call_get_stack = true; if (func_id == BPF_FUNC_get_func_ip) { if (check_get_func_ip(env)) return -ENOTSUPP; env->prog->call_get_func_ip = true; } if (changes_data) clear_all_pkt_pointers(env); return 0; } /* mark_btf_func_reg_size() is used when the reg size is determined by * the BTF func_proto's return value size and argument. */ static void mark_btf_func_reg_size(struct bpf_verifier_env *env, u32 regno, size_t reg_size) { struct bpf_reg_state *reg = &cur_regs(env)[regno]; if (regno == BPF_REG_0) { /* Function return value */ reg->live |= REG_LIVE_WRITTEN; reg->subreg_def = reg_size == sizeof(u64) ? DEF_NOT_SUBREG : env->insn_idx + 1; } else { /* Function argument */ if (reg_size == sizeof(u64)) { mark_insn_zext(env, reg); mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); } else { mark_reg_read(env, reg, reg->parent, REG_LIVE_READ32); } } } static bool is_kfunc_acquire(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_ACQUIRE; } static bool is_kfunc_release(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_RELEASE; } static bool is_kfunc_trusted_args(struct bpf_kfunc_call_arg_meta *meta) { return (meta->kfunc_flags & KF_TRUSTED_ARGS) || is_kfunc_release(meta); } static bool is_kfunc_sleepable(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_SLEEPABLE; } static bool is_kfunc_destructive(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_DESTRUCTIVE; } static bool is_kfunc_rcu(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_RCU; } static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_RCU_PROTECTED; } static bool is_kfunc_arg_mem_size(const struct btf *btf, const struct btf_param *arg, const struct bpf_reg_state *reg) { const struct btf_type *t; t = btf_type_skip_modifiers(btf, arg->type, NULL); if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE) return false; return btf_param_match_suffix(btf, arg, "__sz"); } static bool is_kfunc_arg_const_mem_size(const struct btf *btf, const struct btf_param *arg, const struct bpf_reg_state *reg) { const struct btf_type *t; t = btf_type_skip_modifiers(btf, arg->type, NULL); if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE) return false; return btf_param_match_suffix(btf, arg, "__szk"); } static bool is_kfunc_arg_optional(const struct btf *btf, const struct btf_param *arg) { return btf_param_match_suffix(btf, arg, "__opt"); } static bool is_kfunc_arg_constant(const struct btf *btf, const struct btf_param *arg) { return btf_param_match_suffix(btf, arg, "__k"); } static bool is_kfunc_arg_ignore(const struct btf *btf, const struct btf_param *arg) { return btf_param_match_suffix(btf, arg, "__ign"); } static bool is_kfunc_arg_map(const struct btf *btf, const struct btf_param *arg) { return btf_param_match_suffix(btf, arg, "__map"); } static bool is_kfunc_arg_alloc_obj(const struct btf *btf, const struct btf_param *arg) { return btf_param_match_suffix(btf, arg, "__alloc"); } static bool is_kfunc_arg_uninit(const struct btf *btf, const struct btf_param *arg) { return btf_param_match_suffix(btf, arg, "__uninit"); } static bool is_kfunc_arg_refcounted_kptr(const struct btf *btf, const struct btf_param *arg) { return btf_param_match_suffix(btf, arg, "__refcounted_kptr"); } static bool is_kfunc_arg_nullable(const struct btf *btf, const struct btf_param *arg) { return btf_param_match_suffix(btf, arg, "__nullable"); } static bool is_kfunc_arg_const_str(const struct btf *btf, const struct btf_param *arg) { return btf_param_match_suffix(btf, arg, "__str"); } static bool is_kfunc_arg_scalar_with_name(const struct btf *btf, const struct btf_param *arg, const char *name) { int len, target_len = strlen(name); const char *param_name; param_name = btf_name_by_offset(btf, arg->name_off); if (str_is_empty(param_name)) return false; len = strlen(param_name); if (len != target_len) return false; if (strcmp(param_name, name)) return false; return true; } enum { KF_ARG_DYNPTR_ID, KF_ARG_LIST_HEAD_ID, KF_ARG_LIST_NODE_ID, KF_ARG_RB_ROOT_ID, KF_ARG_RB_NODE_ID, KF_ARG_WORKQUEUE_ID, }; BTF_ID_LIST(kf_arg_btf_ids) BTF_ID(struct, bpf_dynptr) BTF_ID(struct, bpf_list_head) BTF_ID(struct, bpf_list_node) BTF_ID(struct, bpf_rb_root) BTF_ID(struct, bpf_rb_node) BTF_ID(struct, bpf_wq) static bool __is_kfunc_ptr_arg_type(const struct btf *btf, const struct btf_param *arg, int type) { const struct btf_type *t; u32 res_id; t = btf_type_skip_modifiers(btf, arg->type, NULL); if (!t) return false; if (!btf_type_is_ptr(t)) return false; t = btf_type_skip_modifiers(btf, t->type, &res_id); if (!t) return false; return btf_types_are_same(btf, res_id, btf_vmlinux, kf_arg_btf_ids[type]); } static bool is_kfunc_arg_dynptr(const struct btf *btf, const struct btf_param *arg) { return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_DYNPTR_ID); } static bool is_kfunc_arg_list_head(const struct btf *btf, const struct btf_param *arg) { return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_HEAD_ID); } static bool is_kfunc_arg_list_node(const struct btf *btf, const struct btf_param *arg) { return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_NODE_ID); } static bool is_kfunc_arg_rbtree_root(const struct btf *btf, const struct btf_param *arg) { return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_ROOT_ID); } static bool is_kfunc_arg_rbtree_node(const struct btf *btf, const struct btf_param *arg) { return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_NODE_ID); } static bool is_kfunc_arg_wq(const struct btf *btf, const struct btf_param *arg) { return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_WORKQUEUE_ID); } static bool is_kfunc_arg_callback(struct bpf_verifier_env *env, const struct btf *btf, const struct btf_param *arg) { const struct btf_type *t; t = btf_type_resolve_func_ptr(btf, arg->type, NULL); if (!t) return false; return true; } /* Returns true if struct is composed of scalars, 4 levels of nesting allowed */ static bool __btf_type_is_scalar_struct(struct bpf_verifier_env *env, const struct btf *btf, const struct btf_type *t, int rec) { const struct btf_type *member_type; const struct btf_member *member; u32 i; if (!btf_type_is_struct(t)) return false; for_each_member(i, t, member) { const struct btf_array *array; member_type = btf_type_skip_modifiers(btf, member->type, NULL); if (btf_type_is_struct(member_type)) { if (rec >= 3) { verbose(env, "max struct nesting depth exceeded\n"); return false; } if (!__btf_type_is_scalar_struct(env, btf, member_type, rec + 1)) return false; continue; } if (btf_type_is_array(member_type)) { array = btf_array(member_type); if (!array->nelems) return false; member_type = btf_type_skip_modifiers(btf, array->type, NULL); if (!btf_type_is_scalar(member_type)) return false; continue; } if (!btf_type_is_scalar(member_type)) return false; } return true; } enum kfunc_ptr_arg_type { KF_ARG_PTR_TO_CTX, KF_ARG_PTR_TO_ALLOC_BTF_ID, /* Allocated object */ KF_ARG_PTR_TO_REFCOUNTED_KPTR, /* Refcounted local kptr */ KF_ARG_PTR_TO_DYNPTR, KF_ARG_PTR_TO_ITER, KF_ARG_PTR_TO_LIST_HEAD, KF_ARG_PTR_TO_LIST_NODE, KF_ARG_PTR_TO_BTF_ID, /* Also covers reg2btf_ids conversions */ KF_ARG_PTR_TO_MEM, KF_ARG_PTR_TO_MEM_SIZE, /* Size derived from next argument, skip it */ KF_ARG_PTR_TO_CALLBACK, KF_ARG_PTR_TO_RB_ROOT, KF_ARG_PTR_TO_RB_NODE, KF_ARG_PTR_TO_NULL, KF_ARG_PTR_TO_CONST_STR, KF_ARG_PTR_TO_MAP, KF_ARG_PTR_TO_WORKQUEUE, }; enum special_kfunc_type { KF_bpf_obj_new_impl, KF_bpf_obj_drop_impl, KF_bpf_refcount_acquire_impl, KF_bpf_list_push_front_impl, KF_bpf_list_push_back_impl, KF_bpf_list_pop_front, KF_bpf_list_pop_back, KF_bpf_cast_to_kern_ctx, KF_bpf_rdonly_cast, KF_bpf_rcu_read_lock, KF_bpf_rcu_read_unlock, KF_bpf_rbtree_remove, KF_bpf_rbtree_add_impl, KF_bpf_rbtree_first, KF_bpf_dynptr_from_skb, KF_bpf_dynptr_from_xdp, KF_bpf_dynptr_slice, KF_bpf_dynptr_slice_rdwr, KF_bpf_dynptr_clone, KF_bpf_percpu_obj_new_impl, KF_bpf_percpu_obj_drop_impl, KF_bpf_throw, KF_bpf_wq_set_callback_impl, KF_bpf_preempt_disable, KF_bpf_preempt_enable, KF_bpf_iter_css_task_new, KF_bpf_session_cookie, KF_bpf_get_kmem_cache, }; BTF_SET_START(special_kfunc_set) BTF_ID(func, bpf_obj_new_impl) BTF_ID(func, bpf_obj_drop_impl) BTF_ID(func, bpf_refcount_acquire_impl) BTF_ID(func, bpf_list_push_front_impl) BTF_ID(func, bpf_list_push_back_impl) BTF_ID(func, bpf_list_pop_front) BTF_ID(func, bpf_list_pop_back) BTF_ID(func, bpf_cast_to_kern_ctx) BTF_ID(func, bpf_rdonly_cast) BTF_ID(func, bpf_rbtree_remove) BTF_ID(func, bpf_rbtree_add_impl) BTF_ID(func, bpf_rbtree_first) BTF_ID(func, bpf_dynptr_from_skb) BTF_ID(func, bpf_dynptr_from_xdp) BTF_ID(func, bpf_dynptr_slice) BTF_ID(func, bpf_dynptr_slice_rdwr) BTF_ID(func, bpf_dynptr_clone) BTF_ID(func, bpf_percpu_obj_new_impl) BTF_ID(func, bpf_percpu_obj_drop_impl) BTF_ID(func, bpf_throw) BTF_ID(func, bpf_wq_set_callback_impl) #ifdef CONFIG_CGROUPS BTF_ID(func, bpf_iter_css_task_new) #endif BTF_SET_END(special_kfunc_set) BTF_ID_LIST(special_kfunc_list) BTF_ID(func, bpf_obj_new_impl) BTF_ID(func, bpf_obj_drop_impl) BTF_ID(func, bpf_refcount_acquire_impl) BTF_ID(func, bpf_list_push_front_impl) BTF_ID(func, bpf_list_push_back_impl) BTF_ID(func, bpf_list_pop_front) BTF_ID(func, bpf_list_pop_back) BTF_ID(func, bpf_cast_to_kern_ctx) BTF_ID(func, bpf_rdonly_cast) BTF_ID(func, bpf_rcu_read_lock) BTF_ID(func, bpf_rcu_read_unlock) BTF_ID(func, bpf_rbtree_remove) BTF_ID(func, bpf_rbtree_add_impl) BTF_ID(func, bpf_rbtree_first) BTF_ID(func, bpf_dynptr_from_skb) BTF_ID(func, bpf_dynptr_from_xdp) BTF_ID(func, bpf_dynptr_slice) BTF_ID(func, bpf_dynptr_slice_rdwr) BTF_ID(func, bpf_dynptr_clone) BTF_ID(func, bpf_percpu_obj_new_impl) BTF_ID(func, bpf_percpu_obj_drop_impl) BTF_ID(func, bpf_throw) BTF_ID(func, bpf_wq_set_callback_impl) BTF_ID(func, bpf_preempt_disable) BTF_ID(func, bpf_preempt_enable) #ifdef CONFIG_CGROUPS BTF_ID(func, bpf_iter_css_task_new) #else BTF_ID_UNUSED #endif #ifdef CONFIG_BPF_EVENTS BTF_ID(func, bpf_session_cookie) #else BTF_ID_UNUSED #endif BTF_ID(func, bpf_get_kmem_cache) static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta) { if (meta->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl] && meta->arg_owning_ref) { return false; } return meta->kfunc_flags & KF_RET_NULL; } static bool is_kfunc_bpf_rcu_read_lock(struct bpf_kfunc_call_arg_meta *meta) { return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_lock]; } static bool is_kfunc_bpf_rcu_read_unlock(struct bpf_kfunc_call_arg_meta *meta) { return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_unlock]; } static bool is_kfunc_bpf_preempt_disable(struct bpf_kfunc_call_arg_meta *meta) { return meta->func_id == special_kfunc_list[KF_bpf_preempt_disable]; } static bool is_kfunc_bpf_preempt_enable(struct bpf_kfunc_call_arg_meta *meta) { return meta->func_id == special_kfunc_list[KF_bpf_preempt_enable]; } static enum kfunc_ptr_arg_type get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta, const struct btf_type *t, const struct btf_type *ref_t, const char *ref_tname, const struct btf_param *args, int argno, int nargs) { u32 regno = argno + 1; struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *reg = ®s[regno]; bool arg_mem_size = false; if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) return KF_ARG_PTR_TO_CTX; /* In this function, we verify the kfunc's BTF as per the argument type, * leaving the rest of the verification with respect to the register * type to our caller. When a set of conditions hold in the BTF type of * arguments, we resolve it to a known kfunc_ptr_arg_type. */ if (btf_is_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno)) return KF_ARG_PTR_TO_CTX; if (is_kfunc_arg_nullable(meta->btf, &args[argno]) && register_is_null(reg)) return KF_ARG_PTR_TO_NULL; if (is_kfunc_arg_alloc_obj(meta->btf, &args[argno])) return KF_ARG_PTR_TO_ALLOC_BTF_ID; if (is_kfunc_arg_refcounted_kptr(meta->btf, &args[argno])) return KF_ARG_PTR_TO_REFCOUNTED_KPTR; if (is_kfunc_arg_dynptr(meta->btf, &args[argno])) return KF_ARG_PTR_TO_DYNPTR; if (is_kfunc_arg_iter(meta, argno, &args[argno])) return KF_ARG_PTR_TO_ITER; if (is_kfunc_arg_list_head(meta->btf, &args[argno])) return KF_ARG_PTR_TO_LIST_HEAD; if (is_kfunc_arg_list_node(meta->btf, &args[argno])) return KF_ARG_PTR_TO_LIST_NODE; if (is_kfunc_arg_rbtree_root(meta->btf, &args[argno])) return KF_ARG_PTR_TO_RB_ROOT; if (is_kfunc_arg_rbtree_node(meta->btf, &args[argno])) return KF_ARG_PTR_TO_RB_NODE; if (is_kfunc_arg_const_str(meta->btf, &args[argno])) return KF_ARG_PTR_TO_CONST_STR; if (is_kfunc_arg_map(meta->btf, &args[argno])) return KF_ARG_PTR_TO_MAP; if (is_kfunc_arg_wq(meta->btf, &args[argno])) return KF_ARG_PTR_TO_WORKQUEUE; if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) { if (!btf_type_is_struct(ref_t)) { verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n", meta->func_name, argno, btf_type_str(ref_t), ref_tname); return -EINVAL; } return KF_ARG_PTR_TO_BTF_ID; } if (is_kfunc_arg_callback(env, meta->btf, &args[argno])) return KF_ARG_PTR_TO_CALLBACK; if (argno + 1 < nargs && (is_kfunc_arg_mem_size(meta->btf, &args[argno + 1], ®s[regno + 1]) || is_kfunc_arg_const_mem_size(meta->btf, &args[argno + 1], ®s[regno + 1]))) arg_mem_size = true; /* This is the catch all argument type of register types supported by * check_helper_mem_access. However, we only allow when argument type is * pointer to scalar, or struct composed (recursively) of scalars. When * arg_mem_size is true, the pointer can be void *. */ if (!btf_type_is_scalar(ref_t) && !__btf_type_is_scalar_struct(env, meta->btf, ref_t, 0) && (arg_mem_size ? !btf_type_is_void(ref_t) : 1)) { verbose(env, "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n", argno, btf_type_str(ref_t), ref_tname, arg_mem_size ? "void, " : ""); return -EINVAL; } return arg_mem_size ? KF_ARG_PTR_TO_MEM_SIZE : KF_ARG_PTR_TO_MEM; } static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg, const struct btf_type *ref_t, const char *ref_tname, u32 ref_id, struct bpf_kfunc_call_arg_meta *meta, int argno) { const struct btf_type *reg_ref_t; bool strict_type_match = false; const struct btf *reg_btf; const char *reg_ref_tname; bool taking_projection; bool struct_same; u32 reg_ref_id; if (base_type(reg->type) == PTR_TO_BTF_ID) { reg_btf = reg->btf; reg_ref_id = reg->btf_id; } else { reg_btf = btf_vmlinux; reg_ref_id = *reg2btf_ids[base_type(reg->type)]; } /* Enforce strict type matching for calls to kfuncs that are acquiring * or releasing a reference, or are no-cast aliases. We do _not_ * enforce strict matching for plain KF_TRUSTED_ARGS kfuncs by default, * as we want to enable BPF programs to pass types that are bitwise * equivalent without forcing them to explicitly cast with something * like bpf_cast_to_kern_ctx(). * * For example, say we had a type like the following: * * struct bpf_cpumask { * cpumask_t cpumask; * refcount_t usage; * }; * * Note that as specified in <linux/cpumask.h>, cpumask_t is typedef'ed * to a struct cpumask, so it would be safe to pass a struct * bpf_cpumask * to a kfunc expecting a struct cpumask *. * * The philosophy here is similar to how we allow scalars of different * types to be passed to kfuncs as long as the size is the same. The * only difference here is that we're simply allowing * btf_struct_ids_match() to walk the struct at the 0th offset, and * resolve types. */ if ((is_kfunc_release(meta) && reg->ref_obj_id) || btf_type_ids_nocast_alias(&env->log, reg_btf, reg_ref_id, meta->btf, ref_id)) strict_type_match = true; WARN_ON_ONCE(is_kfunc_release(meta) && (reg->off || !tnum_is_const(reg->var_off) || reg->var_off.value)); reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, ®_ref_id); reg_ref_tname = btf_name_by_offset(reg_btf, reg_ref_t->name_off); struct_same = btf_struct_ids_match(&env->log, reg_btf, reg_ref_id, reg->off, meta->btf, ref_id, strict_type_match); /* If kfunc is accepting a projection type (ie. __sk_buff), it cannot * actually use it -- it must cast to the underlying type. So we allow * caller to pass in the underlying type. */ taking_projection = btf_is_projection_of(ref_tname, reg_ref_tname); if (!taking_projection && !struct_same) { verbose(env, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n", meta->func_name, argno, btf_type_str(ref_t), ref_tname, argno + 1, btf_type_str(reg_ref_t), reg_ref_tname); return -EINVAL; } return 0; } static int ref_set_non_owning(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { struct btf_record *rec = reg_btf_record(reg); if (!cur_func(env)->active_locks) { verbose(env, "verifier internal error: ref_set_non_owning w/o active lock\n"); return -EFAULT; } if (type_flag(reg->type) & NON_OWN_REF) { verbose(env, "verifier internal error: NON_OWN_REF already set\n"); return -EFAULT; } reg->type |= NON_OWN_REF; if (rec->refcount_off >= 0) reg->type |= MEM_RCU; return 0; } static int ref_convert_owning_non_owning(struct bpf_verifier_env *env, u32 ref_obj_id) { struct bpf_func_state *state, *unused; struct bpf_reg_state *reg; int i; state = cur_func(env); if (!ref_obj_id) { verbose(env, "verifier internal error: ref_obj_id is zero for " "owning -> non-owning conversion\n"); return -EFAULT; } for (i = 0; i < state->acquired_refs; i++) { if (state->refs[i].id != ref_obj_id) continue; /* Clear ref_obj_id here so release_reference doesn't clobber * the whole reg */ bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({ if (reg->ref_obj_id == ref_obj_id) { reg->ref_obj_id = 0; ref_set_non_owning(env, reg); } })); return 0; } verbose(env, "verifier internal error: ref state missing for ref_obj_id\n"); return -EFAULT; } /* Implementation details: * * Each register points to some region of memory, which we define as an * allocation. Each allocation may embed a bpf_spin_lock which protects any * special BPF objects (bpf_list_head, bpf_rb_root, etc.) part of the same * allocation. The lock and the data it protects are colocated in the same * memory region. * * Hence, everytime a register holds a pointer value pointing to such * allocation, the verifier preserves a unique reg->id for it. * * The verifier remembers the lock 'ptr' and the lock 'id' whenever * bpf_spin_lock is called. * * To enable this, lock state in the verifier captures two values: * active_lock.ptr = Register's type specific pointer * active_lock.id = A unique ID for each register pointer value * * Currently, PTR_TO_MAP_VALUE and PTR_TO_BTF_ID | MEM_ALLOC are the two * supported register types. * * The active_lock.ptr in case of map values is the reg->map_ptr, and in case of * allocated objects is the reg->btf pointer. * * The active_lock.id is non-unique for maps supporting direct_value_addr, as we * can establish the provenance of the map value statically for each distinct * lookup into such maps. They always contain a single map value hence unique * IDs for each pseudo load pessimizes the algorithm and rejects valid programs. * * So, in case of global variables, they use array maps with max_entries = 1, * hence their active_lock.ptr becomes map_ptr and id = 0 (since they all point * into the same map value as max_entries is 1, as described above). * * In case of inner map lookups, the inner map pointer has same map_ptr as the * outer map pointer (in verifier context), but each lookup into an inner map * assigns a fresh reg->id to the lookup, so while lookups into distinct inner * maps from the same outer map share the same map_ptr as active_lock.ptr, they * will get different reg->id assigned to each lookup, hence different * active_lock.id. * * In case of allocated objects, active_lock.ptr is the reg->btf, and the * reg->id is a unique ID preserved after the NULL pointer check on the pointer * returned from bpf_obj_new. Each allocation receives a new reg->id. */ static int check_reg_allocation_locked(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { struct bpf_reference_state *s; void *ptr; u32 id; switch ((int)reg->type) { case PTR_TO_MAP_VALUE: ptr = reg->map_ptr; break; case PTR_TO_BTF_ID | MEM_ALLOC: ptr = reg->btf; break; default: verbose(env, "verifier internal error: unknown reg type for lock check\n"); return -EFAULT; } id = reg->id; if (!cur_func(env)->active_locks) return -EINVAL; s = find_lock_state(env, REF_TYPE_LOCK, id, ptr); if (!s) { verbose(env, "held lock and object are not in the same allocation\n"); return -EINVAL; } return 0; } static bool is_bpf_list_api_kfunc(u32 btf_id) { return btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] || btf_id == special_kfunc_list[KF_bpf_list_push_back_impl] || btf_id == special_kfunc_list[KF_bpf_list_pop_front] || btf_id == special_kfunc_list[KF_bpf_list_pop_back]; } static bool is_bpf_rbtree_api_kfunc(u32 btf_id) { return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl] || btf_id == special_kfunc_list[KF_bpf_rbtree_remove] || btf_id == special_kfunc_list[KF_bpf_rbtree_first]; } static bool is_bpf_graph_api_kfunc(u32 btf_id) { return is_bpf_list_api_kfunc(btf_id) || is_bpf_rbtree_api_kfunc(btf_id) || btf_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]; } static bool is_sync_callback_calling_kfunc(u32 btf_id) { return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl]; } static bool is_async_callback_calling_kfunc(u32 btf_id) { return btf_id == special_kfunc_list[KF_bpf_wq_set_callback_impl]; } static bool is_bpf_throw_kfunc(struct bpf_insn *insn) { return bpf_pseudo_kfunc_call(insn) && insn->off == 0 && insn->imm == special_kfunc_list[KF_bpf_throw]; } static bool is_bpf_wq_set_callback_impl_kfunc(u32 btf_id) { return btf_id == special_kfunc_list[KF_bpf_wq_set_callback_impl]; } static bool is_callback_calling_kfunc(u32 btf_id) { return is_sync_callback_calling_kfunc(btf_id) || is_async_callback_calling_kfunc(btf_id); } static bool is_rbtree_lock_required_kfunc(u32 btf_id) { return is_bpf_rbtree_api_kfunc(btf_id); } static bool check_kfunc_is_graph_root_api(struct bpf_verifier_env *env, enum btf_field_type head_field_type, u32 kfunc_btf_id) { bool ret; switch (head_field_type) { case BPF_LIST_HEAD: ret = is_bpf_list_api_kfunc(kfunc_btf_id); break; case BPF_RB_ROOT: ret = is_bpf_rbtree_api_kfunc(kfunc_btf_id); break; default: verbose(env, "verifier internal error: unexpected graph root argument type %s\n", btf_field_type_name(head_field_type)); return false; } if (!ret) verbose(env, "verifier internal error: %s head arg for unknown kfunc\n", btf_field_type_name(head_field_type)); return ret; } static bool check_kfunc_is_graph_node_api(struct bpf_verifier_env *env, enum btf_field_type node_field_type, u32 kfunc_btf_id) { bool ret; switch (node_field_type) { case BPF_LIST_NODE: ret = (kfunc_btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] || kfunc_btf_id == special_kfunc_list[KF_bpf_list_push_back_impl]); break; case BPF_RB_NODE: ret = (kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_remove] || kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl]); break; default: verbose(env, "verifier internal error: unexpected graph node argument type %s\n", btf_field_type_name(node_field_type)); return false; } if (!ret) verbose(env, "verifier internal error: %s node arg for unknown kfunc\n", btf_field_type_name(node_field_type)); return ret; } static int __process_kf_arg_ptr_to_graph_root(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, struct bpf_kfunc_call_arg_meta *meta, enum btf_field_type head_field_type, struct btf_field **head_field) { const char *head_type_name; struct btf_field *field; struct btf_record *rec; u32 head_off; if (meta->btf != btf_vmlinux) { verbose(env, "verifier internal error: unexpected btf mismatch in kfunc call\n"); return -EFAULT; } if (!check_kfunc_is_graph_root_api(env, head_field_type, meta->func_id)) return -EFAULT; head_type_name = btf_field_type_name(head_field_type); if (!tnum_is_const(reg->var_off)) { verbose(env, "R%d doesn't have constant offset. %s has to be at the constant offset\n", regno, head_type_name); return -EINVAL; } rec = reg_btf_record(reg); head_off = reg->off + reg->var_off.value; field = btf_record_find(rec, head_off, head_field_type); if (!field) { verbose(env, "%s not found at offset=%u\n", head_type_name, head_off); return -EINVAL; } /* All functions require bpf_list_head to be protected using a bpf_spin_lock */ if (check_reg_allocation_locked(env, reg)) { verbose(env, "bpf_spin_lock at off=%d must be held for %s\n", rec->spin_lock_off, head_type_name); return -EINVAL; } if (*head_field) { verbose(env, "verifier internal error: repeating %s arg\n", head_type_name); return -EFAULT; } *head_field = field; return 0; } static int process_kf_arg_ptr_to_list_head(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, struct bpf_kfunc_call_arg_meta *meta) { return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_LIST_HEAD, &meta->arg_list_head.field); } static int process_kf_arg_ptr_to_rbtree_root(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, struct bpf_kfunc_call_arg_meta *meta) { return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_RB_ROOT, &meta->arg_rbtree_root.field); } static int __process_kf_arg_ptr_to_graph_node(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, struct bpf_kfunc_call_arg_meta *meta, enum btf_field_type head_field_type, enum btf_field_type node_field_type, struct btf_field **node_field) { const char *node_type_name; const struct btf_type *et, *t; struct btf_field *field; u32 node_off; if (meta->btf != btf_vmlinux) { verbose(env, "verifier internal error: unexpected btf mismatch in kfunc call\n"); return -EFAULT; } if (!check_kfunc_is_graph_node_api(env, node_field_type, meta->func_id)) return -EFAULT; node_type_name = btf_field_type_name(node_field_type); if (!tnum_is_const(reg->var_off)) { verbose(env, "R%d doesn't have constant offset. %s has to be at the constant offset\n", regno, node_type_name); return -EINVAL; } node_off = reg->off + reg->var_off.value; field = reg_find_field_offset(reg, node_off, node_field_type); if (!field) { verbose(env, "%s not found at offset=%u\n", node_type_name, node_off); return -EINVAL; } field = *node_field; et = btf_type_by_id(field->graph_root.btf, field->graph_root.value_btf_id); t = btf_type_by_id(reg->btf, reg->btf_id); if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, 0, field->graph_root.btf, field->graph_root.value_btf_id, true)) { verbose(env, "operation on %s expects arg#1 %s at offset=%d " "in struct %s, but arg is at offset=%d in struct %s\n", btf_field_type_name(head_field_type), btf_field_type_name(node_field_type), field->graph_root.node_offset, btf_name_by_offset(field->graph_root.btf, et->name_off), node_off, btf_name_by_offset(reg->btf, t->name_off)); return -EINVAL; } meta->arg_btf = reg->btf; meta->arg_btf_id = reg->btf_id; if (node_off != field->graph_root.node_offset) { verbose(env, "arg#1 offset=%d, but expected %s at offset=%d in struct %s\n", node_off, btf_field_type_name(node_field_type), field->graph_root.node_offset, btf_name_by_offset(field->graph_root.btf, et->name_off)); return -EINVAL; } return 0; } static int process_kf_arg_ptr_to_list_node(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, struct bpf_kfunc_call_arg_meta *meta) { return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta, BPF_LIST_HEAD, BPF_LIST_NODE, &meta->arg_list_head.field); } static int process_kf_arg_ptr_to_rbtree_node(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, struct bpf_kfunc_call_arg_meta *meta) { return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta, BPF_RB_ROOT, BPF_RB_NODE, &meta->arg_rbtree_root.field); } /* * css_task iter allowlist is needed to avoid dead locking on css_set_lock. * LSM hooks and iters (both sleepable and non-sleepable) are safe. * Any sleepable progs are also safe since bpf_check_attach_target() enforce * them can only be attached to some specific hook points. */ static bool check_css_task_iter_allowlist(struct bpf_verifier_env *env) { enum bpf_prog_type prog_type = resolve_prog_type(env->prog); switch (prog_type) { case BPF_PROG_TYPE_LSM: return true; case BPF_PROG_TYPE_TRACING: if (env->prog->expected_attach_type == BPF_TRACE_ITER) return true; fallthrough; default: return in_sleepable(env); } } static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta, int insn_idx) { const char *func_name = meta->func_name, *ref_tname; const struct btf *btf = meta->btf; const struct btf_param *args; struct btf_record *rec; u32 i, nargs; int ret; args = (const struct btf_param *)(meta->func_proto + 1); nargs = btf_type_vlen(meta->func_proto); if (nargs > MAX_BPF_FUNC_REG_ARGS) { verbose(env, "Function %s has %d > %d args\n", func_name, nargs, MAX_BPF_FUNC_REG_ARGS); return -EINVAL; } /* Check that BTF function arguments match actual types that the * verifier sees. */ for (i = 0; i < nargs; i++) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[i + 1]; const struct btf_type *t, *ref_t, *resolve_ret; enum bpf_arg_type arg_type = ARG_DONTCARE; u32 regno = i + 1, ref_id, type_size; bool is_ret_buf_sz = false; int kf_arg_type; t = btf_type_skip_modifiers(btf, args[i].type, NULL); if (is_kfunc_arg_ignore(btf, &args[i])) continue; if (btf_type_is_scalar(t)) { if (reg->type != SCALAR_VALUE) { verbose(env, "R%d is not a scalar\n", regno); return -EINVAL; } if (is_kfunc_arg_constant(meta->btf, &args[i])) { if (meta->arg_constant.found) { verbose(env, "verifier internal error: only one constant argument permitted\n"); return -EFAULT; } if (!tnum_is_const(reg->var_off)) { verbose(env, "R%d must be a known constant\n", regno); return -EINVAL; } ret = mark_chain_precision(env, regno); if (ret < 0) return ret; meta->arg_constant.found = true; meta->arg_constant.value = reg->var_off.value; } else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdonly_buf_size")) { meta->r0_rdonly = true; is_ret_buf_sz = true; } else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdwr_buf_size")) { is_ret_buf_sz = true; } if (is_ret_buf_sz) { if (meta->r0_size) { verbose(env, "2 or more rdonly/rdwr_buf_size parameters for kfunc"); return -EINVAL; } if (!tnum_is_const(reg->var_off)) { verbose(env, "R%d is not a const\n", regno); return -EINVAL; } meta->r0_size = reg->var_off.value; ret = mark_chain_precision(env, regno); if (ret) return ret; } continue; } if (!btf_type_is_ptr(t)) { verbose(env, "Unrecognized arg#%d type %s\n", i, btf_type_str(t)); return -EINVAL; } if ((is_kfunc_trusted_args(meta) || is_kfunc_rcu(meta)) && (register_is_null(reg) || type_may_be_null(reg->type)) && !is_kfunc_arg_nullable(meta->btf, &args[i])) { verbose(env, "Possibly NULL pointer passed to trusted arg%d\n", i); return -EACCES; } if (reg->ref_obj_id) { if (is_kfunc_release(meta) && meta->ref_obj_id) { verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n", regno, reg->ref_obj_id, meta->ref_obj_id); return -EFAULT; } meta->ref_obj_id = reg->ref_obj_id; if (is_kfunc_release(meta)) meta->release_regno = regno; } ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id); ref_tname = btf_name_by_offset(btf, ref_t->name_off); kf_arg_type = get_kfunc_ptr_arg_type(env, meta, t, ref_t, ref_tname, args, i, nargs); if (kf_arg_type < 0) return kf_arg_type; switch (kf_arg_type) { case KF_ARG_PTR_TO_NULL: continue; case KF_ARG_PTR_TO_MAP: if (!reg->map_ptr) { verbose(env, "pointer in R%d isn't map pointer\n", regno); return -EINVAL; } if (meta->map.ptr && reg->map_ptr->record->wq_off >= 0) { /* Use map_uid (which is unique id of inner map) to reject: * inner_map1 = bpf_map_lookup_elem(outer_map, key1) * inner_map2 = bpf_map_lookup_elem(outer_map, key2) * if (inner_map1 && inner_map2) { * wq = bpf_map_lookup_elem(inner_map1); * if (wq) * // mismatch would have been allowed * bpf_wq_init(wq, inner_map2); * } * * Comparing map_ptr is enough to distinguish normal and outer maps. */ if (meta->map.ptr != reg->map_ptr || meta->map.uid != reg->map_uid) { verbose(env, "workqueue pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n", meta->map.uid, reg->map_uid); return -EINVAL; } } meta->map.ptr = reg->map_ptr; meta->map.uid = reg->map_uid; fallthrough; case KF_ARG_PTR_TO_ALLOC_BTF_ID: case KF_ARG_PTR_TO_BTF_ID: if (!is_kfunc_trusted_args(meta) && !is_kfunc_rcu(meta)) break; if (!is_trusted_reg(reg)) { if (!is_kfunc_rcu(meta)) { verbose(env, "R%d must be referenced or trusted\n", regno); return -EINVAL; } if (!is_rcu_reg(reg)) { verbose(env, "R%d must be a rcu pointer\n", regno); return -EINVAL; } } fallthrough; case KF_ARG_PTR_TO_CTX: case KF_ARG_PTR_TO_DYNPTR: case KF_ARG_PTR_TO_ITER: case KF_ARG_PTR_TO_LIST_HEAD: case KF_ARG_PTR_TO_LIST_NODE: case KF_ARG_PTR_TO_RB_ROOT: case KF_ARG_PTR_TO_RB_NODE: case KF_ARG_PTR_TO_MEM: case KF_ARG_PTR_TO_MEM_SIZE: case KF_ARG_PTR_TO_CALLBACK: case KF_ARG_PTR_TO_REFCOUNTED_KPTR: case KF_ARG_PTR_TO_CONST_STR: case KF_ARG_PTR_TO_WORKQUEUE: break; default: WARN_ON_ONCE(1); return -EFAULT; } if (is_kfunc_release(meta) && reg->ref_obj_id) arg_type |= OBJ_RELEASE; ret = check_func_arg_reg_off(env, reg, regno, arg_type); if (ret < 0) return ret; switch (kf_arg_type) { case KF_ARG_PTR_TO_CTX: if (reg->type != PTR_TO_CTX) { verbose(env, "arg#%d expected pointer to ctx, but got %s\n", i, reg_type_str(env, reg->type)); return -EINVAL; } if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) { ret = get_kern_ctx_btf_id(&env->log, resolve_prog_type(env->prog)); if (ret < 0) return -EINVAL; meta->ret_btf_id = ret; } break; case KF_ARG_PTR_TO_ALLOC_BTF_ID: if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC)) { if (meta->func_id != special_kfunc_list[KF_bpf_obj_drop_impl]) { verbose(env, "arg#%d expected for bpf_obj_drop_impl()\n", i); return -EINVAL; } } else if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC | MEM_PERCPU)) { if (meta->func_id != special_kfunc_list[KF_bpf_percpu_obj_drop_impl]) { verbose(env, "arg#%d expected for bpf_percpu_obj_drop_impl()\n", i); return -EINVAL; } } else { verbose(env, "arg#%d expected pointer to allocated object\n", i); return -EINVAL; } if (!reg->ref_obj_id) { verbose(env, "allocated object must be referenced\n"); return -EINVAL; } if (meta->btf == btf_vmlinux) { meta->arg_btf = reg->btf; meta->arg_btf_id = reg->btf_id; } break; case KF_ARG_PTR_TO_DYNPTR: { enum bpf_arg_type dynptr_arg_type = ARG_PTR_TO_DYNPTR; int clone_ref_obj_id = 0; if (reg->type == CONST_PTR_TO_DYNPTR) dynptr_arg_type |= MEM_RDONLY; if (is_kfunc_arg_uninit(btf, &args[i])) dynptr_arg_type |= MEM_UNINIT; if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) { dynptr_arg_type |= DYNPTR_TYPE_SKB; } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_xdp]) { dynptr_arg_type |= DYNPTR_TYPE_XDP; } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_clone] && (dynptr_arg_type & MEM_UNINIT)) { enum bpf_dynptr_type parent_type = meta->initialized_dynptr.type; if (parent_type == BPF_DYNPTR_TYPE_INVALID) { verbose(env, "verifier internal error: no dynptr type for parent of clone\n"); return -EFAULT; } dynptr_arg_type |= (unsigned int)get_dynptr_type_flag(parent_type); clone_ref_obj_id = meta->initialized_dynptr.ref_obj_id; if (dynptr_type_refcounted(parent_type) && !clone_ref_obj_id) { verbose(env, "verifier internal error: missing ref obj id for parent of clone\n"); return -EFAULT; } } ret = process_dynptr_func(env, regno, insn_idx, dynptr_arg_type, clone_ref_obj_id); if (ret < 0) return ret; if (!(dynptr_arg_type & MEM_UNINIT)) { int id = dynptr_id(env, reg); if (id < 0) { verbose(env, "verifier internal error: failed to obtain dynptr id\n"); return id; } meta->initialized_dynptr.id = id; meta->initialized_dynptr.type = dynptr_get_type(env, reg); meta->initialized_dynptr.ref_obj_id = dynptr_ref_obj_id(env, reg); } break; } case KF_ARG_PTR_TO_ITER: if (meta->func_id == special_kfunc_list[KF_bpf_iter_css_task_new]) { if (!check_css_task_iter_allowlist(env)) { verbose(env, "css_task_iter is only allowed in bpf_lsm, bpf_iter and sleepable progs\n"); return -EINVAL; } } ret = process_iter_arg(env, regno, insn_idx, meta); if (ret < 0) return ret; break; case KF_ARG_PTR_TO_LIST_HEAD: if (reg->type != PTR_TO_MAP_VALUE && reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) { verbose(env, "arg#%d expected pointer to map value or allocated object\n", i); return -EINVAL; } if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) { verbose(env, "allocated object must be referenced\n"); return -EINVAL; } ret = process_kf_arg_ptr_to_list_head(env, reg, regno, meta); if (ret < 0) return ret; break; case KF_ARG_PTR_TO_RB_ROOT: if (reg->type != PTR_TO_MAP_VALUE && reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) { verbose(env, "arg#%d expected pointer to map value or allocated object\n", i); return -EINVAL; } if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) { verbose(env, "allocated object must be referenced\n"); return -EINVAL; } ret = process_kf_arg_ptr_to_rbtree_root(env, reg, regno, meta); if (ret < 0) return ret; break; case KF_ARG_PTR_TO_LIST_NODE: if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) { verbose(env, "arg#%d expected pointer to allocated object\n", i); return -EINVAL; } if (!reg->ref_obj_id) { verbose(env, "allocated object must be referenced\n"); return -EINVAL; } ret = process_kf_arg_ptr_to_list_node(env, reg, regno, meta); if (ret < 0) return ret; break; case KF_ARG_PTR_TO_RB_NODE: if (meta->func_id == special_kfunc_list[KF_bpf_rbtree_remove]) { if (!type_is_non_owning_ref(reg->type) || reg->ref_obj_id) { verbose(env, "rbtree_remove node input must be non-owning ref\n"); return -EINVAL; } if (in_rbtree_lock_required_cb(env)) { verbose(env, "rbtree_remove not allowed in rbtree cb\n"); return -EINVAL; } } else { if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) { verbose(env, "arg#%d expected pointer to allocated object\n", i); return -EINVAL; } if (!reg->ref_obj_id) { verbose(env, "allocated object must be referenced\n"); return -EINVAL; } } ret = process_kf_arg_ptr_to_rbtree_node(env, reg, regno, meta); if (ret < 0) return ret; break; case KF_ARG_PTR_TO_MAP: /* If argument has '__map' suffix expect 'struct bpf_map *' */ ref_id = *reg2btf_ids[CONST_PTR_TO_MAP]; ref_t = btf_type_by_id(btf_vmlinux, ref_id); ref_tname = btf_name_by_offset(btf, ref_t->name_off); fallthrough; case KF_ARG_PTR_TO_BTF_ID: /* Only base_type is checked, further checks are done here */ if ((base_type(reg->type) != PTR_TO_BTF_ID || (bpf_type_has_unsafe_modifiers(reg->type) && !is_rcu_reg(reg))) && !reg2btf_ids[base_type(reg->type)]) { verbose(env, "arg#%d is %s ", i, reg_type_str(env, reg->type)); verbose(env, "expected %s or socket\n", reg_type_str(env, base_type(reg->type) | (type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS))); return -EINVAL; } ret = process_kf_arg_ptr_to_btf_id(env, reg, ref_t, ref_tname, ref_id, meta, i); if (ret < 0) return ret; break; case KF_ARG_PTR_TO_MEM: resolve_ret = btf_resolve_size(btf, ref_t, &type_size); if (IS_ERR(resolve_ret)) { verbose(env, "arg#%d reference type('%s %s') size cannot be determined: %ld\n", i, btf_type_str(ref_t), ref_tname, PTR_ERR(resolve_ret)); return -EINVAL; } ret = check_mem_reg(env, reg, regno, type_size); if (ret < 0) return ret; break; case KF_ARG_PTR_TO_MEM_SIZE: { struct bpf_reg_state *buff_reg = ®s[regno]; const struct btf_param *buff_arg = &args[i]; struct bpf_reg_state *size_reg = ®s[regno + 1]; const struct btf_param *size_arg = &args[i + 1]; if (!register_is_null(buff_reg) || !is_kfunc_arg_optional(meta->btf, buff_arg)) { ret = check_kfunc_mem_size_reg(env, size_reg, regno + 1); if (ret < 0) { verbose(env, "arg#%d arg#%d memory, len pair leads to invalid memory access\n", i, i + 1); return ret; } } if (is_kfunc_arg_const_mem_size(meta->btf, size_arg, size_reg)) { if (meta->arg_constant.found) { verbose(env, "verifier internal error: only one constant argument permitted\n"); return -EFAULT; } if (!tnum_is_const(size_reg->var_off)) { verbose(env, "R%d must be a known constant\n", regno + 1); return -EINVAL; } meta->arg_constant.found = true; meta->arg_constant.value = size_reg->var_off.value; } /* Skip next '__sz' or '__szk' argument */ i++; break; } case KF_ARG_PTR_TO_CALLBACK: if (reg->type != PTR_TO_FUNC) { verbose(env, "arg%d expected pointer to func\n", i); return -EINVAL; } meta->subprogno = reg->subprogno; break; case KF_ARG_PTR_TO_REFCOUNTED_KPTR: if (!type_is_ptr_alloc_obj(reg->type)) { verbose(env, "arg#%d is neither owning or non-owning ref\n", i); return -EINVAL; } if (!type_is_non_owning_ref(reg->type)) meta->arg_owning_ref = true; rec = reg_btf_record(reg); if (!rec) { verbose(env, "verifier internal error: Couldn't find btf_record\n"); return -EFAULT; } if (rec->refcount_off < 0) { verbose(env, "arg#%d doesn't point to a type with bpf_refcount field\n", i); return -EINVAL; } meta->arg_btf = reg->btf; meta->arg_btf_id = reg->btf_id; break; case KF_ARG_PTR_TO_CONST_STR: if (reg->type != PTR_TO_MAP_VALUE) { verbose(env, "arg#%d doesn't point to a const string\n", i); return -EINVAL; } ret = check_reg_const_str(env, reg, regno); if (ret) return ret; break; case KF_ARG_PTR_TO_WORKQUEUE: if (reg->type != PTR_TO_MAP_VALUE) { verbose(env, "arg#%d doesn't point to a map value\n", i); return -EINVAL; } ret = process_wq_func(env, regno, meta); if (ret < 0) return ret; break; } } if (is_kfunc_release(meta) && !meta->release_regno) { verbose(env, "release kernel function %s expects refcounted PTR_TO_BTF_ID\n", func_name); return -EINVAL; } return 0; } static int fetch_kfunc_meta(struct bpf_verifier_env *env, struct bpf_insn *insn, struct bpf_kfunc_call_arg_meta *meta, const char **kfunc_name) { const struct btf_type *func, *func_proto; u32 func_id, *kfunc_flags; const char *func_name; struct btf *desc_btf; if (kfunc_name) *kfunc_name = NULL; if (!insn->imm) return -EINVAL; desc_btf = find_kfunc_desc_btf(env, insn->off); if (IS_ERR(desc_btf)) return PTR_ERR(desc_btf); func_id = insn->imm; func = btf_type_by_id(desc_btf, func_id); func_name = btf_name_by_offset(desc_btf, func->name_off); if (kfunc_name) *kfunc_name = func_name; func_proto = btf_type_by_id(desc_btf, func->type); kfunc_flags = btf_kfunc_id_set_contains(desc_btf, func_id, env->prog); if (!kfunc_flags) { return -EACCES; } memset(meta, 0, sizeof(*meta)); meta->btf = desc_btf; meta->func_id = func_id; meta->kfunc_flags = *kfunc_flags; meta->func_proto = func_proto; meta->func_name = func_name; return 0; } static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name); static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx_p) { bool sleepable, rcu_lock, rcu_unlock, preempt_disable, preempt_enable; u32 i, nargs, ptr_type_id, release_ref_obj_id; struct bpf_reg_state *regs = cur_regs(env); const char *func_name, *ptr_type_name; const struct btf_type *t, *ptr_type; struct bpf_kfunc_call_arg_meta meta; struct bpf_insn_aux_data *insn_aux; int err, insn_idx = *insn_idx_p; const struct btf_param *args; const struct btf_type *ret_t; struct btf *desc_btf; /* skip for now, but return error when we find this in fixup_kfunc_call */ if (!insn->imm) return 0; err = fetch_kfunc_meta(env, insn, &meta, &func_name); if (err == -EACCES && func_name) verbose(env, "calling kernel function %s is not allowed\n", func_name); if (err) return err; desc_btf = meta.btf; insn_aux = &env->insn_aux_data[insn_idx]; insn_aux->is_iter_next = is_iter_next_kfunc(&meta); if (is_kfunc_destructive(&meta) && !capable(CAP_SYS_BOOT)) { verbose(env, "destructive kfunc calls require CAP_SYS_BOOT capability\n"); return -EACCES; } sleepable = is_kfunc_sleepable(&meta); if (sleepable && !in_sleepable(env)) { verbose(env, "program must be sleepable to call sleepable kfunc %s\n", func_name); return -EACCES; } /* Check the arguments */ err = check_kfunc_args(env, &meta, insn_idx); if (err < 0) return err; if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) { err = push_callback_call(env, insn, insn_idx, meta.subprogno, set_rbtree_add_callback_state); if (err) { verbose(env, "kfunc %s#%d failed callback verification\n", func_name, meta.func_id); return err; } } if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie]) { meta.r0_size = sizeof(u64); meta.r0_rdonly = false; } if (is_bpf_wq_set_callback_impl_kfunc(meta.func_id)) { err = push_callback_call(env, insn, insn_idx, meta.subprogno, set_timer_callback_state); if (err) { verbose(env, "kfunc %s#%d failed callback verification\n", func_name, meta.func_id); return err; } } rcu_lock = is_kfunc_bpf_rcu_read_lock(&meta); rcu_unlock = is_kfunc_bpf_rcu_read_unlock(&meta); preempt_disable = is_kfunc_bpf_preempt_disable(&meta); preempt_enable = is_kfunc_bpf_preempt_enable(&meta); if (env->cur_state->active_rcu_lock) { struct bpf_func_state *state; struct bpf_reg_state *reg; u32 clear_mask = (1 << STACK_SPILL) | (1 << STACK_ITER); if (in_rbtree_lock_required_cb(env) && (rcu_lock || rcu_unlock)) { verbose(env, "Calling bpf_rcu_read_{lock,unlock} in unnecessary rbtree callback\n"); return -EACCES; } if (rcu_lock) { verbose(env, "nested rcu read lock (kernel function %s)\n", func_name); return -EINVAL; } else if (rcu_unlock) { bpf_for_each_reg_in_vstate_mask(env->cur_state, state, reg, clear_mask, ({ if (reg->type & MEM_RCU) { reg->type &= ~(MEM_RCU | PTR_MAYBE_NULL); reg->type |= PTR_UNTRUSTED; } })); env->cur_state->active_rcu_lock = false; } else if (sleepable) { verbose(env, "kernel func %s is sleepable within rcu_read_lock region\n", func_name); return -EACCES; } } else if (rcu_lock) { env->cur_state->active_rcu_lock = true; } else if (rcu_unlock) { verbose(env, "unmatched rcu read unlock (kernel function %s)\n", func_name); return -EINVAL; } if (env->cur_state->active_preempt_lock) { if (preempt_disable) { env->cur_state->active_preempt_lock++; } else if (preempt_enable) { env->cur_state->active_preempt_lock--; } else if (sleepable) { verbose(env, "kernel func %s is sleepable within non-preemptible region\n", func_name); return -EACCES; } } else if (preempt_disable) { env->cur_state->active_preempt_lock++; } else if (preempt_enable) { verbose(env, "unmatched attempt to enable preemption (kernel function %s)\n", func_name); return -EINVAL; } /* In case of release function, we get register number of refcounted * PTR_TO_BTF_ID in bpf_kfunc_arg_meta, do the release now. */ if (meta.release_regno) { err = release_reference(env, regs[meta.release_regno].ref_obj_id); if (err) { verbose(env, "kfunc %s#%d reference has not been acquired before\n", func_name, meta.func_id); return err; } } if (meta.func_id == special_kfunc_list[KF_bpf_list_push_front_impl] || meta.func_id == special_kfunc_list[KF_bpf_list_push_back_impl] || meta.func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) { release_ref_obj_id = regs[BPF_REG_2].ref_obj_id; insn_aux->insert_off = regs[BPF_REG_2].off; insn_aux->kptr_struct_meta = btf_find_struct_meta(meta.arg_btf, meta.arg_btf_id); err = ref_convert_owning_non_owning(env, release_ref_obj_id); if (err) { verbose(env, "kfunc %s#%d conversion of owning ref to non-owning failed\n", func_name, meta.func_id); return err; } err = release_reference(env, release_ref_obj_id); if (err) { verbose(env, "kfunc %s#%d reference has not been acquired before\n", func_name, meta.func_id); return err; } } if (meta.func_id == special_kfunc_list[KF_bpf_throw]) { if (!bpf_jit_supports_exceptions()) { verbose(env, "JIT does not support calling kfunc %s#%d\n", func_name, meta.func_id); return -ENOTSUPP; } env->seen_exception = true; /* In the case of the default callback, the cookie value passed * to bpf_throw becomes the return value of the program. */ if (!env->exception_callback_subprog) { err = check_return_code(env, BPF_REG_1, "R1"); if (err < 0) return err; } } for (i = 0; i < CALLER_SAVED_REGS; i++) mark_reg_not_init(env, regs, caller_saved[i]); /* Check return type */ t = btf_type_skip_modifiers(desc_btf, meta.func_proto->type, NULL); if (is_kfunc_acquire(&meta) && !btf_type_is_struct_ptr(meta.btf, t)) { /* Only exception is bpf_obj_new_impl */ if (meta.btf != btf_vmlinux || (meta.func_id != special_kfunc_list[KF_bpf_obj_new_impl] && meta.func_id != special_kfunc_list[KF_bpf_percpu_obj_new_impl] && meta.func_id != special_kfunc_list[KF_bpf_refcount_acquire_impl])) { verbose(env, "acquire kernel function does not return PTR_TO_BTF_ID\n"); return -EINVAL; } } if (btf_type_is_scalar(t)) { mark_reg_unknown(env, regs, BPF_REG_0); mark_btf_func_reg_size(env, BPF_REG_0, t->size); } else if (btf_type_is_ptr(t)) { ptr_type = btf_type_skip_modifiers(desc_btf, t->type, &ptr_type_id); if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) { if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] || meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { struct btf_struct_meta *struct_meta; struct btf *ret_btf; u32 ret_btf_id; if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] && !bpf_global_ma_set) return -ENOMEM; if (((u64)(u32)meta.arg_constant.value) != meta.arg_constant.value) { verbose(env, "local type ID argument must be in range [0, U32_MAX]\n"); return -EINVAL; } ret_btf = env->prog->aux->btf; ret_btf_id = meta.arg_constant.value; /* This may be NULL due to user not supplying a BTF */ if (!ret_btf) { verbose(env, "bpf_obj_new/bpf_percpu_obj_new requires prog BTF\n"); return -EINVAL; } ret_t = btf_type_by_id(ret_btf, ret_btf_id); if (!ret_t || !__btf_type_is_struct(ret_t)) { verbose(env, "bpf_obj_new/bpf_percpu_obj_new type ID argument must be of a struct\n"); return -EINVAL; } if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { if (ret_t->size > BPF_GLOBAL_PERCPU_MA_MAX_SIZE) { verbose(env, "bpf_percpu_obj_new type size (%d) is greater than %d\n", ret_t->size, BPF_GLOBAL_PERCPU_MA_MAX_SIZE); return -EINVAL; } if (!bpf_global_percpu_ma_set) { mutex_lock(&bpf_percpu_ma_lock); if (!bpf_global_percpu_ma_set) { /* Charge memory allocated with bpf_global_percpu_ma to * root memcg. The obj_cgroup for root memcg is NULL. */ err = bpf_mem_alloc_percpu_init(&bpf_global_percpu_ma, NULL); if (!err) bpf_global_percpu_ma_set = true; } mutex_unlock(&bpf_percpu_ma_lock); if (err) return err; } mutex_lock(&bpf_percpu_ma_lock); err = bpf_mem_alloc_percpu_unit_init(&bpf_global_percpu_ma, ret_t->size); mutex_unlock(&bpf_percpu_ma_lock); if (err) return err; } struct_meta = btf_find_struct_meta(ret_btf, ret_btf_id); if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { if (!__btf_type_is_scalar_struct(env, ret_btf, ret_t, 0)) { verbose(env, "bpf_percpu_obj_new type ID argument must be of a struct of scalars\n"); return -EINVAL; } if (struct_meta) { verbose(env, "bpf_percpu_obj_new type ID argument must not contain special fields\n"); return -EINVAL; } } mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC; regs[BPF_REG_0].btf = ret_btf; regs[BPF_REG_0].btf_id = ret_btf_id; if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) regs[BPF_REG_0].type |= MEM_PERCPU; insn_aux->obj_new_size = ret_t->size; insn_aux->kptr_struct_meta = struct_meta; } else if (meta.func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]) { mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC; regs[BPF_REG_0].btf = meta.arg_btf; regs[BPF_REG_0].btf_id = meta.arg_btf_id; insn_aux->kptr_struct_meta = btf_find_struct_meta(meta.arg_btf, meta.arg_btf_id); } else if (meta.func_id == special_kfunc_list[KF_bpf_list_pop_front] || meta.func_id == special_kfunc_list[KF_bpf_list_pop_back]) { struct btf_field *field = meta.arg_list_head.field; mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root); } else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_remove] || meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) { struct btf_field *field = meta.arg_rbtree_root.field; mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root); } else if (meta.func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) { mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_TRUSTED; regs[BPF_REG_0].btf = desc_btf; regs[BPF_REG_0].btf_id = meta.ret_btf_id; } else if (meta.func_id == special_kfunc_list[KF_bpf_rdonly_cast]) { ret_t = btf_type_by_id(desc_btf, meta.arg_constant.value); if (!ret_t || !btf_type_is_struct(ret_t)) { verbose(env, "kfunc bpf_rdonly_cast type ID argument must be of a struct\n"); return -EINVAL; } mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_UNTRUSTED; regs[BPF_REG_0].btf = desc_btf; regs[BPF_REG_0].btf_id = meta.arg_constant.value; } else if (meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice] || meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice_rdwr]) { enum bpf_type_flag type_flag = get_dynptr_type_flag(meta.initialized_dynptr.type); mark_reg_known_zero(env, regs, BPF_REG_0); if (!meta.arg_constant.found) { verbose(env, "verifier internal error: bpf_dynptr_slice(_rdwr) no constant size\n"); return -EFAULT; } regs[BPF_REG_0].mem_size = meta.arg_constant.value; /* PTR_MAYBE_NULL will be added when is_kfunc_ret_null is checked */ regs[BPF_REG_0].type = PTR_TO_MEM | type_flag; if (meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice]) { regs[BPF_REG_0].type |= MEM_RDONLY; } else { /* this will set env->seen_direct_write to true */ if (!may_access_direct_pkt_data(env, NULL, BPF_WRITE)) { verbose(env, "the prog does not allow writes to packet data\n"); return -EINVAL; } } if (!meta.initialized_dynptr.id) { verbose(env, "verifier internal error: no dynptr id\n"); return -EFAULT; } regs[BPF_REG_0].dynptr_id = meta.initialized_dynptr.id; /* we don't need to set BPF_REG_0's ref obj id * because packet slices are not refcounted (see * dynptr_type_refcounted) */ } else { verbose(env, "kernel function %s unhandled dynamic return type\n", meta.func_name); return -EFAULT; } } else if (btf_type_is_void(ptr_type)) { /* kfunc returning 'void *' is equivalent to returning scalar */ mark_reg_unknown(env, regs, BPF_REG_0); } else if (!__btf_type_is_struct(ptr_type)) { if (!meta.r0_size) { __u32 sz; if (!IS_ERR(btf_resolve_size(desc_btf, ptr_type, &sz))) { meta.r0_size = sz; meta.r0_rdonly = true; } } if (!meta.r0_size) { ptr_type_name = btf_name_by_offset(desc_btf, ptr_type->name_off); verbose(env, "kernel function %s returns pointer type %s %s is not supported\n", func_name, btf_type_str(ptr_type), ptr_type_name); return -EINVAL; } mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_MEM; regs[BPF_REG_0].mem_size = meta.r0_size; if (meta.r0_rdonly) regs[BPF_REG_0].type |= MEM_RDONLY; /* Ensures we don't access the memory after a release_reference() */ if (meta.ref_obj_id) regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id; } else { mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].btf = desc_btf; regs[BPF_REG_0].type = PTR_TO_BTF_ID; regs[BPF_REG_0].btf_id = ptr_type_id; if (meta.func_id == special_kfunc_list[KF_bpf_get_kmem_cache]) regs[BPF_REG_0].type |= PTR_UNTRUSTED; if (is_iter_next_kfunc(&meta)) { struct bpf_reg_state *cur_iter; cur_iter = get_iter_from_state(env->cur_state, &meta); if (cur_iter->type & MEM_RCU) /* KF_RCU_PROTECTED */ regs[BPF_REG_0].type |= MEM_RCU; else regs[BPF_REG_0].type |= PTR_TRUSTED; } } if (is_kfunc_ret_null(&meta)) { regs[BPF_REG_0].type |= PTR_MAYBE_NULL; /* For mark_ptr_or_null_reg, see 93c230e3f5bd6 */ regs[BPF_REG_0].id = ++env->id_gen; } mark_btf_func_reg_size(env, BPF_REG_0, sizeof(void *)); if (is_kfunc_acquire(&meta)) { int id = acquire_reference_state(env, insn_idx); if (id < 0) return id; if (is_kfunc_ret_null(&meta)) regs[BPF_REG_0].id = id; regs[BPF_REG_0].ref_obj_id = id; } else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) { ref_set_non_owning(env, ®s[BPF_REG_0]); } if (reg_may_point_to_spin_lock(®s[BPF_REG_0]) && !regs[BPF_REG_0].id) regs[BPF_REG_0].id = ++env->id_gen; } else if (btf_type_is_void(t)) { if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) { if (meta.func_id == special_kfunc_list[KF_bpf_obj_drop_impl] || meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl]) { insn_aux->kptr_struct_meta = btf_find_struct_meta(meta.arg_btf, meta.arg_btf_id); } } } nargs = btf_type_vlen(meta.func_proto); args = (const struct btf_param *)(meta.func_proto + 1); for (i = 0; i < nargs; i++) { u32 regno = i + 1; t = btf_type_skip_modifiers(desc_btf, args[i].type, NULL); if (btf_type_is_ptr(t)) mark_btf_func_reg_size(env, regno, sizeof(void *)); else /* scalar. ensured by btf_check_kfunc_arg_match() */ mark_btf_func_reg_size(env, regno, t->size); } if (is_iter_next_kfunc(&meta)) { err = process_iter_next_call(env, insn_idx, &meta); if (err) return err; } return 0; } static bool check_reg_sane_offset(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, enum bpf_reg_type type) { bool known = tnum_is_const(reg->var_off); s64 val = reg->var_off.value; s64 smin = reg->smin_value; if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) { verbose(env, "math between %s pointer and %lld is not allowed\n", reg_type_str(env, type), val); return false; } if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) { verbose(env, "%s pointer offset %d is not allowed\n", reg_type_str(env, type), reg->off); return false; } if (smin == S64_MIN) { verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n", reg_type_str(env, type)); return false; } if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) { verbose(env, "value %lld makes %s pointer be out of bounds\n", smin, reg_type_str(env, type)); return false; } return true; } enum { REASON_BOUNDS = -1, REASON_TYPE = -2, REASON_PATHS = -3, REASON_LIMIT = -4, REASON_STACK = -5, }; static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, u32 *alu_limit, bool mask_to_left) { u32 max = 0, ptr_limit = 0; switch (ptr_reg->type) { case PTR_TO_STACK: /* Offset 0 is out-of-bounds, but acceptable start for the * left direction, see BPF_REG_FP. Also, unknown scalar * offset where we would need to deal with min/max bounds is * currently prohibited for unprivileged. */ max = MAX_BPF_STACK + mask_to_left; ptr_limit = -(ptr_reg->var_off.value + ptr_reg->off); break; case PTR_TO_MAP_VALUE: max = ptr_reg->map_ptr->value_size; ptr_limit = (mask_to_left ? ptr_reg->smin_value : ptr_reg->umax_value) + ptr_reg->off; break; default: return REASON_TYPE; } if (ptr_limit >= max) return REASON_LIMIT; *alu_limit = ptr_limit; return 0; } static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env, const struct bpf_insn *insn) { return env->bypass_spec_v1 || BPF_SRC(insn->code) == BPF_K; } static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux, u32 alu_state, u32 alu_limit) { /* If we arrived here from different branches with different * state or limits to sanitize, then this won't work. */ if (aux->alu_state && (aux->alu_state != alu_state || aux->alu_limit != alu_limit)) return REASON_PATHS; /* Corresponding fixup done in do_misc_fixups(). */ aux->alu_state = alu_state; aux->alu_limit = alu_limit; return 0; } static int sanitize_val_alu(struct bpf_verifier_env *env, struct bpf_insn *insn) { struct bpf_insn_aux_data *aux = cur_aux(env); if (can_skip_alu_sanitation(env, insn)) return 0; return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0); } static bool sanitize_needed(u8 opcode) { return opcode == BPF_ADD || opcode == BPF_SUB; } struct bpf_sanitize_info { struct bpf_insn_aux_data aux; bool mask_to_left; }; static struct bpf_verifier_state * sanitize_speculative_path(struct bpf_verifier_env *env, const struct bpf_insn *insn, u32 next_idx, u32 curr_idx) { struct bpf_verifier_state *branch; struct bpf_reg_state *regs; branch = push_stack(env, next_idx, curr_idx, true); if (branch && insn) { regs = branch->frame[branch->curframe]->regs; if (BPF_SRC(insn->code) == BPF_K) { mark_reg_unknown(env, regs, insn->dst_reg); } else if (BPF_SRC(insn->code) == BPF_X) { mark_reg_unknown(env, regs, insn->dst_reg); mark_reg_unknown(env, regs, insn->src_reg); } } return branch; } static int sanitize_ptr_alu(struct bpf_verifier_env *env, struct bpf_insn *insn, const struct bpf_reg_state *ptr_reg, const struct bpf_reg_state *off_reg, struct bpf_reg_state *dst_reg, struct bpf_sanitize_info *info, const bool commit_window) { struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux; struct bpf_verifier_state *vstate = env->cur_state; bool off_is_imm = tnum_is_const(off_reg->var_off); bool off_is_neg = off_reg->smin_value < 0; bool ptr_is_dst_reg = ptr_reg == dst_reg; u8 opcode = BPF_OP(insn->code); u32 alu_state, alu_limit; struct bpf_reg_state tmp; bool ret; int err; if (can_skip_alu_sanitation(env, insn)) return 0; /* We already marked aux for masking from non-speculative * paths, thus we got here in the first place. We only care * to explore bad access from here. */ if (vstate->speculative) goto do_sim; if (!commit_window) { if (!tnum_is_const(off_reg->var_off) && (off_reg->smin_value < 0) != (off_reg->smax_value < 0)) return REASON_BOUNDS; info->mask_to_left = (opcode == BPF_ADD && off_is_neg) || (opcode == BPF_SUB && !off_is_neg); } err = retrieve_ptr_limit(ptr_reg, &alu_limit, info->mask_to_left); if (err < 0) return err; if (commit_window) { /* In commit phase we narrow the masking window based on * the observed pointer move after the simulated operation. */ alu_state = info->aux.alu_state; alu_limit = abs(info->aux.alu_limit - alu_limit); } else { alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0; alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0; alu_state |= ptr_is_dst_reg ? BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST; /* Limit pruning on unknown scalars to enable deep search for * potential masking differences from other program paths. */ if (!off_is_imm) env->explore_alu_limits = true; } err = update_alu_sanitation_state(aux, alu_state, alu_limit); if (err < 0) return err; do_sim: /* If we're in commit phase, we're done here given we already * pushed the truncated dst_reg into the speculative verification * stack. * * Also, when register is a known constant, we rewrite register-based * operation to immediate-based, and thus do not need masking (and as * a consequence, do not need to simulate the zero-truncation either). */ if (commit_window || off_is_imm) return 0; /* Simulate and find potential out-of-bounds access under * speculative execution from truncation as a result of * masking when off was not within expected range. If off * sits in dst, then we temporarily need to move ptr there * to simulate dst (== 0) +/-= ptr. Needed, for example, * for cases where we use K-based arithmetic in one direction * and truncated reg-based in the other in order to explore * bad access. */ if (!ptr_is_dst_reg) { tmp = *dst_reg; copy_register_state(dst_reg, ptr_reg); } ret = sanitize_speculative_path(env, NULL, env->insn_idx + 1, env->insn_idx); if (!ptr_is_dst_reg && ret) *dst_reg = tmp; return !ret ? REASON_STACK : 0; } static void sanitize_mark_insn_seen(struct bpf_verifier_env *env) { struct bpf_verifier_state *vstate = env->cur_state; /* If we simulate paths under speculation, we don't update the * insn as 'seen' such that when we verify unreachable paths in * the non-speculative domain, sanitize_dead_code() can still * rewrite/sanitize them. */ if (!vstate->speculative) env->insn_aux_data[env->insn_idx].seen = env->pass_cnt; } static int sanitize_err(struct bpf_verifier_env *env, const struct bpf_insn *insn, int reason, const struct bpf_reg_state *off_reg, const struct bpf_reg_state *dst_reg) { static const char *err = "pointer arithmetic with it prohibited for !root"; const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub"; u32 dst = insn->dst_reg, src = insn->src_reg; switch (reason) { case REASON_BOUNDS: verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n", off_reg == dst_reg ? dst : src, err); break; case REASON_TYPE: verbose(env, "R%d has pointer with unsupported alu operation, %s\n", off_reg == dst_reg ? src : dst, err); break; case REASON_PATHS: verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n", dst, op, err); break; case REASON_LIMIT: verbose(env, "R%d tried to %s beyond pointer bounds, %s\n", dst, op, err); break; case REASON_STACK: verbose(env, "R%d could not be pushed for speculative verification, %s\n", dst, err); break; default: verbose(env, "verifier internal error: unknown reason (%d)\n", reason); break; } return -EACCES; } /* check that stack access falls within stack limits and that 'reg' doesn't * have a variable offset. * * Variable offset is prohibited for unprivileged mode for simplicity since it * requires corresponding support in Spectre masking for stack ALU. See also * retrieve_ptr_limit(). * * * 'off' includes 'reg->off'. */ static int check_stack_access_for_ptr_arithmetic( struct bpf_verifier_env *env, int regno, const struct bpf_reg_state *reg, int off) { if (!tnum_is_const(reg->var_off)) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n", regno, tn_buf, off); return -EACCES; } if (off >= 0 || off < -MAX_BPF_STACK) { verbose(env, "R%d stack pointer arithmetic goes out of range, " "prohibited for !root; off=%d\n", regno, off); return -EACCES; } return 0; } static int sanitize_check_bounds(struct bpf_verifier_env *env, const struct bpf_insn *insn, const struct bpf_reg_state *dst_reg) { u32 dst = insn->dst_reg; /* For unprivileged we require that resulting offset must be in bounds * in order to be able to sanitize access later on. */ if (env->bypass_spec_v1) return 0; switch (dst_reg->type) { case PTR_TO_STACK: if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg, dst_reg->off + dst_reg->var_off.value)) return -EACCES; break; case PTR_TO_MAP_VALUE: if (check_map_access(env, dst, dst_reg->off, 1, false, ACCESS_HELPER)) { verbose(env, "R%d pointer arithmetic of map value goes out of range, " "prohibited for !root\n", dst); return -EACCES; } break; default: break; } return 0; } /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off. * Caller should also handle BPF_MOV case separately. * If we return -EACCES, caller may want to try again treating pointer as a * scalar. So we only emit a diagnostic if !env->allow_ptr_leaks. */ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, struct bpf_insn *insn, const struct bpf_reg_state *ptr_reg, const struct bpf_reg_state *off_reg) { struct bpf_verifier_state *vstate = env->cur_state; struct bpf_func_state *state = vstate->frame[vstate->curframe]; struct bpf_reg_state *regs = state->regs, *dst_reg; bool known = tnum_is_const(off_reg->var_off); s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value, smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value; u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value, umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value; struct bpf_sanitize_info info = {}; u8 opcode = BPF_OP(insn->code); u32 dst = insn->dst_reg; int ret; dst_reg = ®s[dst]; if ((known && (smin_val != smax_val || umin_val != umax_val)) || smin_val > smax_val || umin_val > umax_val) { /* Taint dst register if offset had invalid bounds derived from * e.g. dead branches. */ __mark_reg_unknown(env, dst_reg); return 0; } if (BPF_CLASS(insn->code) != BPF_ALU64) { /* 32-bit ALU ops on pointers produce (meaningless) scalars */ if (opcode == BPF_SUB && env->allow_ptr_leaks) { __mark_reg_unknown(env, dst_reg); return 0; } verbose(env, "R%d 32-bit pointer arithmetic prohibited\n", dst); return -EACCES; } if (ptr_reg->type & PTR_MAYBE_NULL) { verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n", dst, reg_type_str(env, ptr_reg->type)); return -EACCES; } switch (base_type(ptr_reg->type)) { case PTR_TO_CTX: case PTR_TO_MAP_VALUE: case PTR_TO_MAP_KEY: case PTR_TO_STACK: case PTR_TO_PACKET_META: case PTR_TO_PACKET: case PTR_TO_TP_BUFFER: case PTR_TO_BTF_ID: case PTR_TO_MEM: case PTR_TO_BUF: case PTR_TO_FUNC: case CONST_PTR_TO_DYNPTR: break; case PTR_TO_FLOW_KEYS: if (known) break; fallthrough; case CONST_PTR_TO_MAP: /* smin_val represents the known value */ if (known && smin_val == 0 && opcode == BPF_ADD) break; fallthrough; default: verbose(env, "R%d pointer arithmetic on %s prohibited\n", dst, reg_type_str(env, ptr_reg->type)); return -EACCES; } /* In case of 'scalar += pointer', dst_reg inherits pointer type and id. * The id may be overwritten later if we create a new variable offset. */ dst_reg->type = ptr_reg->type; dst_reg->id = ptr_reg->id; if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) || !check_reg_sane_offset(env, ptr_reg, ptr_reg->type)) return -EINVAL; /* pointer types do not carry 32-bit bounds at the moment. */ __mark_reg32_unbounded(dst_reg); if (sanitize_needed(opcode)) { ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg, &info, false); if (ret < 0) return sanitize_err(env, insn, ret, off_reg, dst_reg); } switch (opcode) { case BPF_ADD: /* We can take a fixed offset as long as it doesn't overflow * the s32 'off' field */ if (known && (ptr_reg->off + smin_val == (s64)(s32)(ptr_reg->off + smin_val))) { /* pointer += K. Accumulate it into fixed offset */ dst_reg->smin_value = smin_ptr; dst_reg->smax_value = smax_ptr; dst_reg->umin_value = umin_ptr; dst_reg->umax_value = umax_ptr; dst_reg->var_off = ptr_reg->var_off; dst_reg->off = ptr_reg->off + smin_val; dst_reg->raw = ptr_reg->raw; break; } /* A new variable offset is created. Note that off_reg->off * == 0, since it's a scalar. * dst_reg gets the pointer type and since some positive * integer value was added to the pointer, give it a new 'id' * if it's a PTR_TO_PACKET. * this creates a new 'base' pointer, off_reg (variable) gets * added into the variable offset, and we copy the fixed offset * from ptr_reg. */ if (check_add_overflow(smin_ptr, smin_val, &dst_reg->smin_value) || check_add_overflow(smax_ptr, smax_val, &dst_reg->smax_value)) { dst_reg->smin_value = S64_MIN; dst_reg->smax_value = S64_MAX; } if (check_add_overflow(umin_ptr, umin_val, &dst_reg->umin_value) || check_add_overflow(umax_ptr, umax_val, &dst_reg->umax_value)) { dst_reg->umin_value = 0; dst_reg->umax_value = U64_MAX; } dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off); dst_reg->off = ptr_reg->off; dst_reg->raw = ptr_reg->raw; if (reg_is_pkt_pointer(ptr_reg)) { dst_reg->id = ++env->id_gen; /* something was added to pkt_ptr, set range to zero */ memset(&dst_reg->raw, 0, sizeof(dst_reg->raw)); } break; case BPF_SUB: if (dst_reg == off_reg) { /* scalar -= pointer. Creates an unknown scalar */ verbose(env, "R%d tried to subtract pointer from scalar\n", dst); return -EACCES; } /* We don't allow subtraction from FP, because (according to * test_verifier.c test "invalid fp arithmetic", JITs might not * be able to deal with it. */ if (ptr_reg->type == PTR_TO_STACK) { verbose(env, "R%d subtraction from stack pointer prohibited\n", dst); return -EACCES; } if (known && (ptr_reg->off - smin_val == (s64)(s32)(ptr_reg->off - smin_val))) { /* pointer -= K. Subtract it from fixed offset */ dst_reg->smin_value = smin_ptr; dst_reg->smax_value = smax_ptr; dst_reg->umin_value = umin_ptr; dst_reg->umax_value = umax_ptr; dst_reg->var_off = ptr_reg->var_off; dst_reg->id = ptr_reg->id; dst_reg->off = ptr_reg->off - smin_val; dst_reg->raw = ptr_reg->raw; break; } /* A new variable offset is created. If the subtrahend is known * nonnegative, then any reg->range we had before is still good. */ if (check_sub_overflow(smin_ptr, smax_val, &dst_reg->smin_value) || check_sub_overflow(smax_ptr, smin_val, &dst_reg->smax_value)) { /* Overflow possible, we know nothing */ dst_reg->smin_value = S64_MIN; dst_reg->smax_value = S64_MAX; } if (umin_ptr < umax_val) { /* Overflow possible, we know nothing */ dst_reg->umin_value = 0; dst_reg->umax_value = U64_MAX; } else { /* Cannot overflow (as long as bounds are consistent) */ dst_reg->umin_value = umin_ptr - umax_val; dst_reg->umax_value = umax_ptr - umin_val; } dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off); dst_reg->off = ptr_reg->off; dst_reg->raw = ptr_reg->raw; if (reg_is_pkt_pointer(ptr_reg)) { dst_reg->id = ++env->id_gen; /* something was added to pkt_ptr, set range to zero */ if (smin_val < 0) memset(&dst_reg->raw, 0, sizeof(dst_reg->raw)); } break; case BPF_AND: case BPF_OR: case BPF_XOR: /* bitwise ops on pointers are troublesome, prohibit. */ verbose(env, "R%d bitwise operator %s on pointer prohibited\n", dst, bpf_alu_string[opcode >> 4]); return -EACCES; default: /* other operators (e.g. MUL,LSH) produce non-pointer results */ verbose(env, "R%d pointer arithmetic with %s operator prohibited\n", dst, bpf_alu_string[opcode >> 4]); return -EACCES; } if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type)) return -EINVAL; reg_bounds_sync(dst_reg); if (sanitize_check_bounds(env, insn, dst_reg) < 0) return -EACCES; if (sanitize_needed(opcode)) { ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg, &info, true); if (ret < 0) return sanitize_err(env, insn, ret, off_reg, dst_reg); } return 0; } static void scalar32_min_max_add(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { s32 *dst_smin = &dst_reg->s32_min_value; s32 *dst_smax = &dst_reg->s32_max_value; u32 *dst_umin = &dst_reg->u32_min_value; u32 *dst_umax = &dst_reg->u32_max_value; if (check_add_overflow(*dst_smin, src_reg->s32_min_value, dst_smin) || check_add_overflow(*dst_smax, src_reg->s32_max_value, dst_smax)) { *dst_smin = S32_MIN; *dst_smax = S32_MAX; } if (check_add_overflow(*dst_umin, src_reg->u32_min_value, dst_umin) || check_add_overflow(*dst_umax, src_reg->u32_max_value, dst_umax)) { *dst_umin = 0; *dst_umax = U32_MAX; } } static void scalar_min_max_add(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { s64 *dst_smin = &dst_reg->smin_value; s64 *dst_smax = &dst_reg->smax_value; u64 *dst_umin = &dst_reg->umin_value; u64 *dst_umax = &dst_reg->umax_value; if (check_add_overflow(*dst_smin, src_reg->smin_value, dst_smin) || check_add_overflow(*dst_smax, src_reg->smax_value, dst_smax)) { *dst_smin = S64_MIN; *dst_smax = S64_MAX; } if (check_add_overflow(*dst_umin, src_reg->umin_value, dst_umin) || check_add_overflow(*dst_umax, src_reg->umax_value, dst_umax)) { *dst_umin = 0; *dst_umax = U64_MAX; } } static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { s32 *dst_smin = &dst_reg->s32_min_value; s32 *dst_smax = &dst_reg->s32_max_value; u32 umin_val = src_reg->u32_min_value; u32 umax_val = src_reg->u32_max_value; if (check_sub_overflow(*dst_smin, src_reg->s32_max_value, dst_smin) || check_sub_overflow(*dst_smax, src_reg->s32_min_value, dst_smax)) { /* Overflow possible, we know nothing */ *dst_smin = S32_MIN; *dst_smax = S32_MAX; } if (dst_reg->u32_min_value < umax_val) { /* Overflow possible, we know nothing */ dst_reg->u32_min_value = 0; dst_reg->u32_max_value = U32_MAX; } else { /* Cannot overflow (as long as bounds are consistent) */ dst_reg->u32_min_value -= umax_val; dst_reg->u32_max_value -= umin_val; } } static void scalar_min_max_sub(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { s64 *dst_smin = &dst_reg->smin_value; s64 *dst_smax = &dst_reg->smax_value; u64 umin_val = src_reg->umin_value; u64 umax_val = src_reg->umax_value; if (check_sub_overflow(*dst_smin, src_reg->smax_value, dst_smin) || check_sub_overflow(*dst_smax, src_reg->smin_value, dst_smax)) { /* Overflow possible, we know nothing */ *dst_smin = S64_MIN; *dst_smax = S64_MAX; } if (dst_reg->umin_value < umax_val) { /* Overflow possible, we know nothing */ dst_reg->umin_value = 0; dst_reg->umax_value = U64_MAX; } else { /* Cannot overflow (as long as bounds are consistent) */ dst_reg->umin_value -= umax_val; dst_reg->umax_value -= umin_val; } } static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { s32 smin_val = src_reg->s32_min_value; u32 umin_val = src_reg->u32_min_value; u32 umax_val = src_reg->u32_max_value; if (smin_val < 0 || dst_reg->s32_min_value < 0) { /* Ain't nobody got time to multiply that sign */ __mark_reg32_unbounded(dst_reg); return; } /* Both values are positive, so we can work with unsigned and * copy the result to signed (unless it exceeds S32_MAX). */ if (umax_val > U16_MAX || dst_reg->u32_max_value > U16_MAX) { /* Potential overflow, we know nothing */ __mark_reg32_unbounded(dst_reg); return; } dst_reg->u32_min_value *= umin_val; dst_reg->u32_max_value *= umax_val; if (dst_reg->u32_max_value > S32_MAX) { /* Overflow possible, we know nothing */ dst_reg->s32_min_value = S32_MIN; dst_reg->s32_max_value = S32_MAX; } else { dst_reg->s32_min_value = dst_reg->u32_min_value; dst_reg->s32_max_value = dst_reg->u32_max_value; } } static void scalar_min_max_mul(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { s64 smin_val = src_reg->smin_value; u64 umin_val = src_reg->umin_value; u64 umax_val = src_reg->umax_value; if (smin_val < 0 || dst_reg->smin_value < 0) { /* Ain't nobody got time to multiply that sign */ __mark_reg64_unbounded(dst_reg); return; } /* Both values are positive, so we can work with unsigned and * copy the result to signed (unless it exceeds S64_MAX). */ if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) { /* Potential overflow, we know nothing */ __mark_reg64_unbounded(dst_reg); return; } dst_reg->umin_value *= umin_val; dst_reg->umax_value *= umax_val; if (dst_reg->umax_value > S64_MAX) { /* Overflow possible, we know nothing */ dst_reg->smin_value = S64_MIN; dst_reg->smax_value = S64_MAX; } else { dst_reg->smin_value = dst_reg->umin_value; dst_reg->smax_value = dst_reg->umax_value; } } static void scalar32_min_max_and(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { bool src_known = tnum_subreg_is_const(src_reg->var_off); bool dst_known = tnum_subreg_is_const(dst_reg->var_off); struct tnum var32_off = tnum_subreg(dst_reg->var_off); u32 umax_val = src_reg->u32_max_value; if (src_known && dst_known) { __mark_reg32_known(dst_reg, var32_off.value); return; } /* We get our minimum from the var_off, since that's inherently * bitwise. Our maximum is the minimum of the operands' maxima. */ dst_reg->u32_min_value = var32_off.value; dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val); /* Safe to set s32 bounds by casting u32 result into s32 when u32 * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded. */ if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) { dst_reg->s32_min_value = dst_reg->u32_min_value; dst_reg->s32_max_value = dst_reg->u32_max_value; } else { dst_reg->s32_min_value = S32_MIN; dst_reg->s32_max_value = S32_MAX; } } static void scalar_min_max_and(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { bool src_known = tnum_is_const(src_reg->var_off); bool dst_known = tnum_is_const(dst_reg->var_off); u64 umax_val = src_reg->umax_value; if (src_known && dst_known) { __mark_reg_known(dst_reg, dst_reg->var_off.value); return; } /* We get our minimum from the var_off, since that's inherently * bitwise. Our maximum is the minimum of the operands' maxima. */ dst_reg->umin_value = dst_reg->var_off.value; dst_reg->umax_value = min(dst_reg->umax_value, umax_val); /* Safe to set s64 bounds by casting u64 result into s64 when u64 * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded. */ if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) { dst_reg->smin_value = dst_reg->umin_value; dst_reg->smax_value = dst_reg->umax_value; } else { dst_reg->smin_value = S64_MIN; dst_reg->smax_value = S64_MAX; } /* We may learn something more from the var_off */ __update_reg_bounds(dst_reg); } static void scalar32_min_max_or(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { bool src_known = tnum_subreg_is_const(src_reg->var_off); bool dst_known = tnum_subreg_is_const(dst_reg->var_off); struct tnum var32_off = tnum_subreg(dst_reg->var_off); u32 umin_val = src_reg->u32_min_value; if (src_known && dst_known) { __mark_reg32_known(dst_reg, var32_off.value); return; } /* We get our maximum from the var_off, and our minimum is the * maximum of the operands' minima */ dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val); dst_reg->u32_max_value = var32_off.value | var32_off.mask; /* Safe to set s32 bounds by casting u32 result into s32 when u32 * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded. */ if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) { dst_reg->s32_min_value = dst_reg->u32_min_value; dst_reg->s32_max_value = dst_reg->u32_max_value; } else { dst_reg->s32_min_value = S32_MIN; dst_reg->s32_max_value = S32_MAX; } } static void scalar_min_max_or(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { bool src_known = tnum_is_const(src_reg->var_off); bool dst_known = tnum_is_const(dst_reg->var_off); u64 umin_val = src_reg->umin_value; if (src_known && dst_known) { __mark_reg_known(dst_reg, dst_reg->var_off.value); return; } /* We get our maximum from the var_off, and our minimum is the * maximum of the operands' minima */ dst_reg->umin_value = max(dst_reg->umin_value, umin_val); dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask; /* Safe to set s64 bounds by casting u64 result into s64 when u64 * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded. */ if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) { dst_reg->smin_value = dst_reg->umin_value; dst_reg->smax_value = dst_reg->umax_value; } else { dst_reg->smin_value = S64_MIN; dst_reg->smax_value = S64_MAX; } /* We may learn something more from the var_off */ __update_reg_bounds(dst_reg); } static void scalar32_min_max_xor(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { bool src_known = tnum_subreg_is_const(src_reg->var_off); bool dst_known = tnum_subreg_is_const(dst_reg->var_off); struct tnum var32_off = tnum_subreg(dst_reg->var_off); if (src_known && dst_known) { __mark_reg32_known(dst_reg, var32_off.value); return; } /* We get both minimum and maximum from the var32_off. */ dst_reg->u32_min_value = var32_off.value; dst_reg->u32_max_value = var32_off.value | var32_off.mask; /* Safe to set s32 bounds by casting u32 result into s32 when u32 * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded. */ if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) { dst_reg->s32_min_value = dst_reg->u32_min_value; dst_reg->s32_max_value = dst_reg->u32_max_value; } else { dst_reg->s32_min_value = S32_MIN; dst_reg->s32_max_value = S32_MAX; } } static void scalar_min_max_xor(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { bool src_known = tnum_is_const(src_reg->var_off); bool dst_known = tnum_is_const(dst_reg->var_off); if (src_known && dst_known) { /* dst_reg->var_off.value has been updated earlier */ __mark_reg_known(dst_reg, dst_reg->var_off.value); return; } /* We get both minimum and maximum from the var_off. */ dst_reg->umin_value = dst_reg->var_off.value; dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask; /* Safe to set s64 bounds by casting u64 result into s64 when u64 * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded. */ if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) { dst_reg->smin_value = dst_reg->umin_value; dst_reg->smax_value = dst_reg->umax_value; } else { dst_reg->smin_value = S64_MIN; dst_reg->smax_value = S64_MAX; } __update_reg_bounds(dst_reg); } static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg, u64 umin_val, u64 umax_val) { /* We lose all sign bit information (except what we can pick * up from var_off) */ dst_reg->s32_min_value = S32_MIN; dst_reg->s32_max_value = S32_MAX; /* If we might shift our top bit out, then we know nothing */ if (umax_val > 31 || dst_reg->u32_max_value > 1ULL << (31 - umax_val)) { dst_reg->u32_min_value = 0; dst_reg->u32_max_value = U32_MAX; } else { dst_reg->u32_min_value <<= umin_val; dst_reg->u32_max_value <<= umax_val; } } static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { u32 umax_val = src_reg->u32_max_value; u32 umin_val = src_reg->u32_min_value; /* u32 alu operation will zext upper bits */ struct tnum subreg = tnum_subreg(dst_reg->var_off); __scalar32_min_max_lsh(dst_reg, umin_val, umax_val); dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val)); /* Not required but being careful mark reg64 bounds as unknown so * that we are forced to pick them up from tnum and zext later and * if some path skips this step we are still safe. */ __mark_reg64_unbounded(dst_reg); __update_reg32_bounds(dst_reg); } static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg, u64 umin_val, u64 umax_val) { /* Special case <<32 because it is a common compiler pattern to sign * extend subreg by doing <<32 s>>32. In this case if 32bit bounds are * positive we know this shift will also be positive so we can track * bounds correctly. Otherwise we lose all sign bit information except * what we can pick up from var_off. Perhaps we can generalize this * later to shifts of any length. */ if (umin_val == 32 && umax_val == 32 && dst_reg->s32_max_value >= 0) dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32; else dst_reg->smax_value = S64_MAX; if (umin_val == 32 && umax_val == 32 && dst_reg->s32_min_value >= 0) dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32; else dst_reg->smin_value = S64_MIN; /* If we might shift our top bit out, then we know nothing */ if (dst_reg->umax_value > 1ULL << (63 - umax_val)) { dst_reg->umin_value = 0; dst_reg->umax_value = U64_MAX; } else { dst_reg->umin_value <<= umin_val; dst_reg->umax_value <<= umax_val; } } static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { u64 umax_val = src_reg->umax_value; u64 umin_val = src_reg->umin_value; /* scalar64 calc uses 32bit unshifted bounds so must be called first */ __scalar64_min_max_lsh(dst_reg, umin_val, umax_val); __scalar32_min_max_lsh(dst_reg, umin_val, umax_val); dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val); /* We may learn something more from the var_off */ __update_reg_bounds(dst_reg); } static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { struct tnum subreg = tnum_subreg(dst_reg->var_off); u32 umax_val = src_reg->u32_max_value; u32 umin_val = src_reg->u32_min_value; /* BPF_RSH is an unsigned shift. If the value in dst_reg might * be negative, then either: * 1) src_reg might be zero, so the sign bit of the result is * unknown, so we lose our signed bounds * 2) it's known negative, thus the unsigned bounds capture the * signed bounds * 3) the signed bounds cross zero, so they tell us nothing * about the result * If the value in dst_reg is known nonnegative, then again the * unsigned bounds capture the signed bounds. * Thus, in all cases it suffices to blow away our signed bounds * and rely on inferring new ones from the unsigned bounds and * var_off of the result. */ dst_reg->s32_min_value = S32_MIN; dst_reg->s32_max_value = S32_MAX; dst_reg->var_off = tnum_rshift(subreg, umin_val); dst_reg->u32_min_value >>= umax_val; dst_reg->u32_max_value >>= umin_val; __mark_reg64_unbounded(dst_reg); __update_reg32_bounds(dst_reg); } static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { u64 umax_val = src_reg->umax_value; u64 umin_val = src_reg->umin_value; /* BPF_RSH is an unsigned shift. If the value in dst_reg might * be negative, then either: * 1) src_reg might be zero, so the sign bit of the result is * unknown, so we lose our signed bounds * 2) it's known negative, thus the unsigned bounds capture the * signed bounds * 3) the signed bounds cross zero, so they tell us nothing * about the result * If the value in dst_reg is known nonnegative, then again the * unsigned bounds capture the signed bounds. * Thus, in all cases it suffices to blow away our signed bounds * and rely on inferring new ones from the unsigned bounds and * var_off of the result. */ dst_reg->smin_value = S64_MIN; dst_reg->smax_value = S64_MAX; dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val); dst_reg->umin_value >>= umax_val; dst_reg->umax_value >>= umin_val; /* Its not easy to operate on alu32 bounds here because it depends * on bits being shifted in. Take easy way out and mark unbounded * so we can recalculate later from tnum. */ __mark_reg32_unbounded(dst_reg); __update_reg_bounds(dst_reg); } static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { u64 umin_val = src_reg->u32_min_value; /* Upon reaching here, src_known is true and * umax_val is equal to umin_val. */ dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val); dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val); dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 32); /* blow away the dst_reg umin_value/umax_value and rely on * dst_reg var_off to refine the result. */ dst_reg->u32_min_value = 0; dst_reg->u32_max_value = U32_MAX; __mark_reg64_unbounded(dst_reg); __update_reg32_bounds(dst_reg); } static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg) { u64 umin_val = src_reg->umin_value; /* Upon reaching here, src_known is true and umax_val is equal * to umin_val. */ dst_reg->smin_value >>= umin_val; dst_reg->smax_value >>= umin_val; dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 64); /* blow away the dst_reg umin_value/umax_value and rely on * dst_reg var_off to refine the result. */ dst_reg->umin_value = 0; dst_reg->umax_value = U64_MAX; /* Its not easy to operate on alu32 bounds here because it depends * on bits being shifted in from upper 32-bits. Take easy way out * and mark unbounded so we can recalculate later from tnum. */ __mark_reg32_unbounded(dst_reg); __update_reg_bounds(dst_reg); } static bool is_safe_to_compute_dst_reg_range(struct bpf_insn *insn, const struct bpf_reg_state *src_reg) { bool src_is_const = false; u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32; if (insn_bitness == 32) { if (tnum_subreg_is_const(src_reg->var_off) && src_reg->s32_min_value == src_reg->s32_max_value && src_reg->u32_min_value == src_reg->u32_max_value) src_is_const = true; } else { if (tnum_is_const(src_reg->var_off) && src_reg->smin_value == src_reg->smax_value && src_reg->umin_value == src_reg->umax_value) src_is_const = true; } switch (BPF_OP(insn->code)) { case BPF_ADD: case BPF_SUB: case BPF_AND: case BPF_XOR: case BPF_OR: case BPF_MUL: return true; /* Shift operators range is only computable if shift dimension operand * is a constant. Shifts greater than 31 or 63 are undefined. This * includes shifts by a negative number. */ case BPF_LSH: case BPF_RSH: case BPF_ARSH: return (src_is_const && src_reg->umax_value < insn_bitness); default: return false; } } /* WARNING: This function does calculations on 64-bit values, but the actual * execution may occur on 32-bit values. Therefore, things like bitshifts * need extra checks in the 32-bit case. */ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, struct bpf_insn *insn, struct bpf_reg_state *dst_reg, struct bpf_reg_state src_reg) { u8 opcode = BPF_OP(insn->code); bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64); int ret; if (!is_safe_to_compute_dst_reg_range(insn, &src_reg)) { __mark_reg_unknown(env, dst_reg); return 0; } if (sanitize_needed(opcode)) { ret = sanitize_val_alu(env, insn); if (ret < 0) return sanitize_err(env, insn, ret, NULL, NULL); } /* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops. * There are two classes of instructions: The first class we track both * alu32 and alu64 sign/unsigned bounds independently this provides the * greatest amount of precision when alu operations are mixed with jmp32 * operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD, * and BPF_OR. This is possible because these ops have fairly easy to * understand and calculate behavior in both 32-bit and 64-bit alu ops. * See alu32 verifier tests for examples. The second class of * operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy * with regards to tracking sign/unsigned bounds because the bits may * cross subreg boundaries in the alu64 case. When this happens we mark * the reg unbounded in the subreg bound space and use the resulting * tnum to calculate an approximation of the sign/unsigned bounds. */ switch (opcode) { case BPF_ADD: scalar32_min_max_add(dst_reg, &src_reg); scalar_min_max_add(dst_reg, &src_reg); dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off); break; case BPF_SUB: scalar32_min_max_sub(dst_reg, &src_reg); scalar_min_max_sub(dst_reg, &src_reg); dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off); break; case BPF_MUL: dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off); scalar32_min_max_mul(dst_reg, &src_reg); scalar_min_max_mul(dst_reg, &src_reg); break; case BPF_AND: dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off); scalar32_min_max_and(dst_reg, &src_reg); scalar_min_max_and(dst_reg, &src_reg); break; case BPF_OR: dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off); scalar32_min_max_or(dst_reg, &src_reg); scalar_min_max_or(dst_reg, &src_reg); break; case BPF_XOR: dst_reg->var_off = tnum_xor(dst_reg->var_off, src_reg.var_off); scalar32_min_max_xor(dst_reg, &src_reg); scalar_min_max_xor(dst_reg, &src_reg); break; case BPF_LSH: if (alu32) scalar32_min_max_lsh(dst_reg, &src_reg); else scalar_min_max_lsh(dst_reg, &src_reg); break; case BPF_RSH: if (alu32) scalar32_min_max_rsh(dst_reg, &src_reg); else scalar_min_max_rsh(dst_reg, &src_reg); break; case BPF_ARSH: if (alu32) scalar32_min_max_arsh(dst_reg, &src_reg); else scalar_min_max_arsh(dst_reg, &src_reg); break; default: break; } /* ALU32 ops are zero extended into 64bit register */ if (alu32) zext_32_to_64(dst_reg); reg_bounds_sync(dst_reg); return 0; } /* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max * and var_off. */ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, struct bpf_insn *insn) { struct bpf_verifier_state *vstate = env->cur_state; struct bpf_func_state *state = vstate->frame[vstate->curframe]; struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg; struct bpf_reg_state *ptr_reg = NULL, off_reg = {0}; bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64); u8 opcode = BPF_OP(insn->code); int err; dst_reg = ®s[insn->dst_reg]; src_reg = NULL; if (dst_reg->type == PTR_TO_ARENA) { struct bpf_insn_aux_data *aux = cur_aux(env); if (BPF_CLASS(insn->code) == BPF_ALU64) /* * 32-bit operations zero upper bits automatically. * 64-bit operations need to be converted to 32. */ aux->needs_zext = true; /* Any arithmetic operations are allowed on arena pointers */ return 0; } if (dst_reg->type != SCALAR_VALUE) ptr_reg = dst_reg; if (BPF_SRC(insn->code) == BPF_X) { src_reg = ®s[insn->src_reg]; if (src_reg->type != SCALAR_VALUE) { if (dst_reg->type != SCALAR_VALUE) { /* Combining two pointers by any ALU op yields * an arbitrary scalar. Disallow all math except * pointer subtraction */ if (opcode == BPF_SUB && env->allow_ptr_leaks) { mark_reg_unknown(env, regs, insn->dst_reg); return 0; } verbose(env, "R%d pointer %s pointer prohibited\n", insn->dst_reg, bpf_alu_string[opcode >> 4]); return -EACCES; } else { /* scalar += pointer * This is legal, but we have to reverse our * src/dest handling in computing the range */ err = mark_chain_precision(env, insn->dst_reg); if (err) return err; return adjust_ptr_min_max_vals(env, insn, src_reg, dst_reg); } } else if (ptr_reg) { /* pointer += scalar */ err = mark_chain_precision(env, insn->src_reg); if (err) return err; return adjust_ptr_min_max_vals(env, insn, dst_reg, src_reg); } else if (dst_reg->precise) { /* if dst_reg is precise, src_reg should be precise as well */ err = mark_chain_precision(env, insn->src_reg); if (err) return err; } } else { /* Pretend the src is a reg with a known value, since we only * need to be able to read from this state. */ off_reg.type = SCALAR_VALUE; __mark_reg_known(&off_reg, insn->imm); src_reg = &off_reg; if (ptr_reg) /* pointer += K */ return adjust_ptr_min_max_vals(env, insn, ptr_reg, src_reg); } /* Got here implies adding two SCALAR_VALUEs */ if (WARN_ON_ONCE(ptr_reg)) { print_verifier_state(env, state, true); verbose(env, "verifier internal error: unexpected ptr_reg\n"); return -EINVAL; } if (WARN_ON(!src_reg)) { print_verifier_state(env, state, true); verbose(env, "verifier internal error: no src_reg\n"); return -EINVAL; } err = adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg); if (err) return err; /* * Compilers can generate the code * r1 = r2 * r1 += 0x1 * if r2 < 1000 goto ... * use r1 in memory access * So for 64-bit alu remember constant delta between r2 and r1 and * update r1 after 'if' condition. */ if (env->bpf_capable && BPF_OP(insn->code) == BPF_ADD && !alu32 && dst_reg->id && is_reg_const(src_reg, false)) { u64 val = reg_const_value(src_reg, false); if ((dst_reg->id & BPF_ADD_CONST) || /* prevent overflow in sync_linked_regs() later */ val > (u32)S32_MAX) { /* * If the register already went through rX += val * we cannot accumulate another val into rx->off. */ dst_reg->off = 0; dst_reg->id = 0; } else { dst_reg->id |= BPF_ADD_CONST; dst_reg->off = val; } } else { /* * Make sure ID is cleared otherwise dst_reg min/max could be * incorrectly propagated into other registers by sync_linked_regs() */ dst_reg->id = 0; } return 0; } /* check validity of 32-bit and 64-bit arithmetic operations */ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) { struct bpf_reg_state *regs = cur_regs(env); u8 opcode = BPF_OP(insn->code); int err; if (opcode == BPF_END || opcode == BPF_NEG) { if (opcode == BPF_NEG) { if (BPF_SRC(insn->code) != BPF_K || insn->src_reg != BPF_REG_0 || insn->off != 0 || insn->imm != 0) { verbose(env, "BPF_NEG uses reserved fields\n"); return -EINVAL; } } else { if (insn->src_reg != BPF_REG_0 || insn->off != 0 || (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) || (BPF_CLASS(insn->code) == BPF_ALU64 && BPF_SRC(insn->code) != BPF_TO_LE)) { verbose(env, "BPF_END uses reserved fields\n"); return -EINVAL; } } /* check src operand */ err = check_reg_arg(env, insn->dst_reg, SRC_OP); if (err) return err; if (is_pointer_value(env, insn->dst_reg)) { verbose(env, "R%d pointer arithmetic prohibited\n", insn->dst_reg); return -EACCES; } /* check dest operand */ err = check_reg_arg(env, insn->dst_reg, DST_OP); if (err) return err; } else if (opcode == BPF_MOV) { if (BPF_SRC(insn->code) == BPF_X) { if (BPF_CLASS(insn->code) == BPF_ALU) { if ((insn->off != 0 && insn->off != 8 && insn->off != 16) || insn->imm) { verbose(env, "BPF_MOV uses reserved fields\n"); return -EINVAL; } } else if (insn->off == BPF_ADDR_SPACE_CAST) { if (insn->imm != 1 && insn->imm != 1u << 16) { verbose(env, "addr_space_cast insn can only convert between address space 1 and 0\n"); return -EINVAL; } if (!env->prog->aux->arena) { verbose(env, "addr_space_cast insn can only be used in a program that has an associated arena\n"); return -EINVAL; } } else { if ((insn->off != 0 && insn->off != 8 && insn->off != 16 && insn->off != 32) || insn->imm) { verbose(env, "BPF_MOV uses reserved fields\n"); return -EINVAL; } } /* check src operand */ err = check_reg_arg(env, insn->src_reg, SRC_OP); if (err) return err; } else { if (insn->src_reg != BPF_REG_0 || insn->off != 0) { verbose(env, "BPF_MOV uses reserved fields\n"); return -EINVAL; } } /* check dest operand, mark as required later */ err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); if (err) return err; if (BPF_SRC(insn->code) == BPF_X) { struct bpf_reg_state *src_reg = regs + insn->src_reg; struct bpf_reg_state *dst_reg = regs + insn->dst_reg; if (BPF_CLASS(insn->code) == BPF_ALU64) { if (insn->imm) { /* off == BPF_ADDR_SPACE_CAST */ mark_reg_unknown(env, regs, insn->dst_reg); if (insn->imm == 1) { /* cast from as(1) to as(0) */ dst_reg->type = PTR_TO_ARENA; /* PTR_TO_ARENA is 32-bit */ dst_reg->subreg_def = env->insn_idx + 1; } } else if (insn->off == 0) { /* case: R1 = R2 * copy register state to dest reg */ assign_scalar_id_before_mov(env, src_reg); copy_register_state(dst_reg, src_reg); dst_reg->live |= REG_LIVE_WRITTEN; dst_reg->subreg_def = DEF_NOT_SUBREG; } else { /* case: R1 = (s8, s16 s32)R2 */ if (is_pointer_value(env, insn->src_reg)) { verbose(env, "R%d sign-extension part of pointer\n", insn->src_reg); return -EACCES; } else if (src_reg->type == SCALAR_VALUE) { bool no_sext; no_sext = src_reg->umax_value < (1ULL << (insn->off - 1)); if (no_sext) assign_scalar_id_before_mov(env, src_reg); copy_register_state(dst_reg, src_reg); if (!no_sext) dst_reg->id = 0; coerce_reg_to_size_sx(dst_reg, insn->off >> 3); dst_reg->live |= REG_LIVE_WRITTEN; dst_reg->subreg_def = DEF_NOT_SUBREG; } else { mark_reg_unknown(env, regs, insn->dst_reg); } } } else { /* R1 = (u32) R2 */ if (is_pointer_value(env, insn->src_reg)) { verbose(env, "R%d partial copy of pointer\n", insn->src_reg); return -EACCES; } else if (src_reg->type == SCALAR_VALUE) { if (insn->off == 0) { bool is_src_reg_u32 = get_reg_width(src_reg) <= 32; if (is_src_reg_u32) assign_scalar_id_before_mov(env, src_reg); copy_register_state(dst_reg, src_reg); /* Make sure ID is cleared if src_reg is not in u32 * range otherwise dst_reg min/max could be incorrectly * propagated into src_reg by sync_linked_regs() */ if (!is_src_reg_u32) dst_reg->id = 0; dst_reg->live |= REG_LIVE_WRITTEN; dst_reg->subreg_def = env->insn_idx + 1; } else { /* case: W1 = (s8, s16)W2 */ bool no_sext = src_reg->umax_value < (1ULL << (insn->off - 1)); if (no_sext) assign_scalar_id_before_mov(env, src_reg); copy_register_state(dst_reg, src_reg); if (!no_sext) dst_reg->id = 0; dst_reg->live |= REG_LIVE_WRITTEN; dst_reg->subreg_def = env->insn_idx + 1; coerce_subreg_to_size_sx(dst_reg, insn->off >> 3); } } else { mark_reg_unknown(env, regs, insn->dst_reg); } zext_32_to_64(dst_reg); reg_bounds_sync(dst_reg); } } else { /* case: R = imm * remember the value we stored into this reg */ /* clear any state __mark_reg_known doesn't set */ mark_reg_unknown(env, regs, insn->dst_reg); regs[insn->dst_reg].type = SCALAR_VALUE; if (BPF_CLASS(insn->code) == BPF_ALU64) { __mark_reg_known(regs + insn->dst_reg, insn->imm); } else { __mark_reg_known(regs + insn->dst_reg, (u32)insn->imm); } } } else if (opcode > BPF_END) { verbose(env, "invalid BPF_ALU opcode %x\n", opcode); return -EINVAL; } else { /* all other ALU ops: and, sub, xor, add, ... */ if (BPF_SRC(insn->code) == BPF_X) { if (insn->imm != 0 || insn->off > 1 || (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) { verbose(env, "BPF_ALU uses reserved fields\n"); return -EINVAL; } /* check src1 operand */ err = check_reg_arg(env, insn->src_reg, SRC_OP); if (err) return err; } else { if (insn->src_reg != BPF_REG_0 || insn->off > 1 || (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) { verbose(env, "BPF_ALU uses reserved fields\n"); return -EINVAL; } } /* check src2 operand */ err = check_reg_arg(env, insn->dst_reg, SRC_OP); if (err) return err; if ((opcode == BPF_MOD || opcode == BPF_DIV) && BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { verbose(env, "div by zero\n"); return -EINVAL; } if ((opcode == BPF_LSH || opcode == BPF_RSH || opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; if (insn->imm < 0 || insn->imm >= size) { verbose(env, "invalid shift %d\n", insn->imm); return -EINVAL; } } /* check dest operand */ err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); err = err ?: adjust_reg_min_max_vals(env, insn); if (err) return err; } return reg_bounds_sanity_check(env, ®s[insn->dst_reg], "alu"); } static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, struct bpf_reg_state *dst_reg, enum bpf_reg_type type, bool range_right_open) { struct bpf_func_state *state; struct bpf_reg_state *reg; int new_range; if (dst_reg->off < 0 || (dst_reg->off == 0 && range_right_open)) /* This doesn't give us any range */ return; if (dst_reg->umax_value > MAX_PACKET_OFF || dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF) /* Risk of overflow. For instance, ptr + (1<<63) may be less * than pkt_end, but that's because it's also less than pkt. */ return; new_range = dst_reg->off; if (range_right_open) new_range++; /* Examples for register markings: * * pkt_data in dst register: * * r2 = r3; * r2 += 8; * if (r2 > pkt_end) goto <handle exception> * <access okay> * * r2 = r3; * r2 += 8; * if (r2 < pkt_end) goto <access okay> * <handle exception> * * Where: * r2 == dst_reg, pkt_end == src_reg * r2=pkt(id=n,off=8,r=0) * r3=pkt(id=n,off=0,r=0) * * pkt_data in src register: * * r2 = r3; * r2 += 8; * if (pkt_end >= r2) goto <access okay> * <handle exception> * * r2 = r3; * r2 += 8; * if (pkt_end <= r2) goto <handle exception> * <access okay> * * Where: * pkt_end == dst_reg, r2 == src_reg * r2=pkt(id=n,off=8,r=0) * r3=pkt(id=n,off=0,r=0) * * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8) * and [r3, r3 + 8-1) respectively is safe to access depending on * the check. */ /* If our ids match, then we must have the same max_value. And we * don't care about the other reg's fixed offset, since if it's too big * the range won't allow anything. * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16. */ bpf_for_each_reg_in_vstate(vstate, state, reg, ({ if (reg->type == type && reg->id == dst_reg->id) /* keep the maximum range already checked */ reg->range = max(reg->range, new_range); })); } /* * <reg1> <op> <reg2>, currently assuming reg2 is a constant */ static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode, bool is_jmp32) { struct tnum t1 = is_jmp32 ? tnum_subreg(reg1->var_off) : reg1->var_off; struct tnum t2 = is_jmp32 ? tnum_subreg(reg2->var_off) : reg2->var_off; u64 umin1 = is_jmp32 ? (u64)reg1->u32_min_value : reg1->umin_value; u64 umax1 = is_jmp32 ? (u64)reg1->u32_max_value : reg1->umax_value; s64 smin1 = is_jmp32 ? (s64)reg1->s32_min_value : reg1->smin_value; s64 smax1 = is_jmp32 ? (s64)reg1->s32_max_value : reg1->smax_value; u64 umin2 = is_jmp32 ? (u64)reg2->u32_min_value : reg2->umin_value; u64 umax2 = is_jmp32 ? (u64)reg2->u32_max_value : reg2->umax_value; s64 smin2 = is_jmp32 ? (s64)reg2->s32_min_value : reg2->smin_value; s64 smax2 = is_jmp32 ? (s64)reg2->s32_max_value : reg2->smax_value; switch (opcode) { case BPF_JEQ: /* constants, umin/umax and smin/smax checks would be * redundant in this case because they all should match */ if (tnum_is_const(t1) && tnum_is_const(t2)) return t1.value == t2.value; /* non-overlapping ranges */ if (umin1 > umax2 || umax1 < umin2) return 0; if (smin1 > smax2 || smax1 < smin2) return 0; if (!is_jmp32) { /* if 64-bit ranges are inconclusive, see if we can * utilize 32-bit subrange knowledge to eliminate * branches that can't be taken a priori */ if (reg1->u32_min_value > reg2->u32_max_value || reg1->u32_max_value < reg2->u32_min_value) return 0; if (reg1->s32_min_value > reg2->s32_max_value || reg1->s32_max_value < reg2->s32_min_value) return 0; } break; case BPF_JNE: /* constants, umin/umax and smin/smax checks would be * redundant in this case because they all should match */ if (tnum_is_const(t1) && tnum_is_const(t2)) return t1.value != t2.value; /* non-overlapping ranges */ if (umin1 > umax2 || umax1 < umin2) return 1; if (smin1 > smax2 || smax1 < smin2) return 1; if (!is_jmp32) { /* if 64-bit ranges are inconclusive, see if we can * utilize 32-bit subrange knowledge to eliminate * branches that can't be taken a priori */ if (reg1->u32_min_value > reg2->u32_max_value || reg1->u32_max_value < reg2->u32_min_value) return 1; if (reg1->s32_min_value > reg2->s32_max_value || reg1->s32_max_value < reg2->s32_min_value) return 1; } break; case BPF_JSET: if (!is_reg_const(reg2, is_jmp32)) { swap(reg1, reg2); swap(t1, t2); } if (!is_reg_const(reg2, is_jmp32)) return -1; if ((~t1.mask & t1.value) & t2.value) return 1; if (!((t1.mask | t1.value) & t2.value)) return 0; break; case BPF_JGT: if (umin1 > umax2) return 1; else if (umax1 <= umin2) return 0; break; case BPF_JSGT: if (smin1 > smax2) return 1; else if (smax1 <= smin2) return 0; break; case BPF_JLT: if (umax1 < umin2) return 1; else if (umin1 >= umax2) return 0; break; case BPF_JSLT: if (smax1 < smin2) return 1; else if (smin1 >= smax2) return 0; break; case BPF_JGE: if (umin1 >= umax2) return 1; else if (umax1 < umin2) return 0; break; case BPF_JSGE: if (smin1 >= smax2) return 1; else if (smax1 < smin2) return 0; break; case BPF_JLE: if (umax1 <= umin2) return 1; else if (umin1 > umax2) return 0; break; case BPF_JSLE: if (smax1 <= smin2) return 1; else if (smin1 > smax2) return 0; break; } return -1; } static int flip_opcode(u32 opcode) { /* How can we transform "a <op> b" into "b <op> a"? */ static const u8 opcode_flip[16] = { /* these stay the same */ [BPF_JEQ >> 4] = BPF_JEQ, [BPF_JNE >> 4] = BPF_JNE, [BPF_JSET >> 4] = BPF_JSET, /* these swap "lesser" and "greater" (L and G in the opcodes) */ [BPF_JGE >> 4] = BPF_JLE, [BPF_JGT >> 4] = BPF_JLT, [BPF_JLE >> 4] = BPF_JGE, [BPF_JLT >> 4] = BPF_JGT, [BPF_JSGE >> 4] = BPF_JSLE, [BPF_JSGT >> 4] = BPF_JSLT, [BPF_JSLE >> 4] = BPF_JSGE, [BPF_JSLT >> 4] = BPF_JSGT }; return opcode_flip[opcode >> 4]; } static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg, u8 opcode) { struct bpf_reg_state *pkt; if (src_reg->type == PTR_TO_PACKET_END) { pkt = dst_reg; } else if (dst_reg->type == PTR_TO_PACKET_END) { pkt = src_reg; opcode = flip_opcode(opcode); } else { return -1; } if (pkt->range >= 0) return -1; switch (opcode) { case BPF_JLE: /* pkt <= pkt_end */ fallthrough; case BPF_JGT: /* pkt > pkt_end */ if (pkt->range == BEYOND_PKT_END) /* pkt has at last one extra byte beyond pkt_end */ return opcode == BPF_JGT; break; case BPF_JLT: /* pkt < pkt_end */ fallthrough; case BPF_JGE: /* pkt >= pkt_end */ if (pkt->range == BEYOND_PKT_END || pkt->range == AT_PKT_END) return opcode == BPF_JGE; break; } return -1; } /* compute branch direction of the expression "if (<reg1> opcode <reg2>) goto target;" * and return: * 1 - branch will be taken and "goto target" will be executed * 0 - branch will not be taken and fall-through to next insn * -1 - unknown. Example: "if (reg1 < 5)" is unknown when register value * range [0,10] */ static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode, bool is_jmp32) { if (reg_is_pkt_pointer_any(reg1) && reg_is_pkt_pointer_any(reg2) && !is_jmp32) return is_pkt_ptr_branch_taken(reg1, reg2, opcode); if (__is_pointer_value(false, reg1) || __is_pointer_value(false, reg2)) { u64 val; /* arrange that reg2 is a scalar, and reg1 is a pointer */ if (!is_reg_const(reg2, is_jmp32)) { opcode = flip_opcode(opcode); swap(reg1, reg2); } /* and ensure that reg2 is a constant */ if (!is_reg_const(reg2, is_jmp32)) return -1; if (!reg_not_null(reg1)) return -1; /* If pointer is valid tests against zero will fail so we can * use this to direct branch taken. */ val = reg_const_value(reg2, is_jmp32); if (val != 0) return -1; switch (opcode) { case BPF_JEQ: return 0; case BPF_JNE: return 1; default: return -1; } } /* now deal with two scalars, but not necessarily constants */ return is_scalar_branch_taken(reg1, reg2, opcode, is_jmp32); } /* Opcode that corresponds to a *false* branch condition. * E.g., if r1 < r2, then reverse (false) condition is r1 >= r2 */ static u8 rev_opcode(u8 opcode) { switch (opcode) { case BPF_JEQ: return BPF_JNE; case BPF_JNE: return BPF_JEQ; /* JSET doesn't have it's reverse opcode in BPF, so add * BPF_X flag to denote the reverse of that operation */ case BPF_JSET: return BPF_JSET | BPF_X; case BPF_JSET | BPF_X: return BPF_JSET; case BPF_JGE: return BPF_JLT; case BPF_JGT: return BPF_JLE; case BPF_JLE: return BPF_JGT; case BPF_JLT: return BPF_JGE; case BPF_JSGE: return BPF_JSLT; case BPF_JSGT: return BPF_JSLE; case BPF_JSLE: return BPF_JSGT; case BPF_JSLT: return BPF_JSGE; default: return 0; } } /* Refine range knowledge for <reg1> <op> <reg>2 conditional operation. */ static void regs_refine_cond_op(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode, bool is_jmp32) { struct tnum t; u64 val; /* In case of GE/GT/SGE/JST, reuse LE/LT/SLE/SLT logic from below */ switch (opcode) { case BPF_JGE: case BPF_JGT: case BPF_JSGE: case BPF_JSGT: opcode = flip_opcode(opcode); swap(reg1, reg2); break; default: break; } switch (opcode) { case BPF_JEQ: if (is_jmp32) { reg1->u32_min_value = max(reg1->u32_min_value, reg2->u32_min_value); reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value); reg1->s32_min_value = max(reg1->s32_min_value, reg2->s32_min_value); reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value); reg2->u32_min_value = reg1->u32_min_value; reg2->u32_max_value = reg1->u32_max_value; reg2->s32_min_value = reg1->s32_min_value; reg2->s32_max_value = reg1->s32_max_value; t = tnum_intersect(tnum_subreg(reg1->var_off), tnum_subreg(reg2->var_off)); reg1->var_off = tnum_with_subreg(reg1->var_off, t); reg2->var_off = tnum_with_subreg(reg2->var_off, t); } else { reg1->umin_value = max(reg1->umin_value, reg2->umin_value); reg1->umax_value = min(reg1->umax_value, reg2->umax_value); reg1->smin_value = max(reg1->smin_value, reg2->smin_value); reg1->smax_value = min(reg1->smax_value, reg2->smax_value); reg2->umin_value = reg1->umin_value; reg2->umax_value = reg1->umax_value; reg2->smin_value = reg1->smin_value; reg2->smax_value = reg1->smax_value; reg1->var_off = tnum_intersect(reg1->var_off, reg2->var_off); reg2->var_off = reg1->var_off; } break; case BPF_JNE: if (!is_reg_const(reg2, is_jmp32)) swap(reg1, reg2); if (!is_reg_const(reg2, is_jmp32)) break; /* try to recompute the bound of reg1 if reg2 is a const and * is exactly the edge of reg1. */ val = reg_const_value(reg2, is_jmp32); if (is_jmp32) { /* u32_min_value is not equal to 0xffffffff at this point, * because otherwise u32_max_value is 0xffffffff as well, * in such a case both reg1 and reg2 would be constants, * jump would be predicted and reg_set_min_max() won't * be called. * * Same reasoning works for all {u,s}{min,max}{32,64} cases * below. */ if (reg1->u32_min_value == (u32)val) reg1->u32_min_value++; if (reg1->u32_max_value == (u32)val) reg1->u32_max_value--; if (reg1->s32_min_value == (s32)val) reg1->s32_min_value++; if (reg1->s32_max_value == (s32)val) reg1->s32_max_value--; } else { if (reg1->umin_value == (u64)val) reg1->umin_value++; if (reg1->umax_value == (u64)val) reg1->umax_value--; if (reg1->smin_value == (s64)val) reg1->smin_value++; if (reg1->smax_value == (s64)val) reg1->smax_value--; } break; case BPF_JSET: if (!is_reg_const(reg2, is_jmp32)) swap(reg1, reg2); if (!is_reg_const(reg2, is_jmp32)) break; val = reg_const_value(reg2, is_jmp32); /* BPF_JSET (i.e., TRUE branch, *not* BPF_JSET | BPF_X) * requires single bit to learn something useful. E.g., if we * know that `r1 & 0x3` is true, then which bits (0, 1, or both) * are actually set? We can learn something definite only if * it's a single-bit value to begin with. * * BPF_JSET | BPF_X (i.e., negation of BPF_JSET) doesn't have * this restriction. I.e., !(r1 & 0x3) means neither bit 0 nor * bit 1 is set, which we can readily use in adjustments. */ if (!is_power_of_2(val)) break; if (is_jmp32) { t = tnum_or(tnum_subreg(reg1->var_off), tnum_const(val)); reg1->var_off = tnum_with_subreg(reg1->var_off, t); } else { reg1->var_off = tnum_or(reg1->var_off, tnum_const(val)); } break; case BPF_JSET | BPF_X: /* reverse of BPF_JSET, see rev_opcode() */ if (!is_reg_const(reg2, is_jmp32)) swap(reg1, reg2); if (!is_reg_const(reg2, is_jmp32)) break; val = reg_const_value(reg2, is_jmp32); if (is_jmp32) { t = tnum_and(tnum_subreg(reg1->var_off), tnum_const(~val)); reg1->var_off = tnum_with_subreg(reg1->var_off, t); } else { reg1->var_off = tnum_and(reg1->var_off, tnum_const(~val)); } break; case BPF_JLE: if (is_jmp32) { reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value); reg2->u32_min_value = max(reg1->u32_min_value, reg2->u32_min_value); } else { reg1->umax_value = min(reg1->umax_value, reg2->umax_value); reg2->umin_value = max(reg1->umin_value, reg2->umin_value); } break; case BPF_JLT: if (is_jmp32) { reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value - 1); reg2->u32_min_value = max(reg1->u32_min_value + 1, reg2->u32_min_value); } else { reg1->umax_value = min(reg1->umax_value, reg2->umax_value - 1); reg2->umin_value = max(reg1->umin_value + 1, reg2->umin_value); } break; case BPF_JSLE: if (is_jmp32) { reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value); reg2->s32_min_value = max(reg1->s32_min_value, reg2->s32_min_value); } else { reg1->smax_value = min(reg1->smax_value, reg2->smax_value); reg2->smin_value = max(reg1->smin_value, reg2->smin_value); } break; case BPF_JSLT: if (is_jmp32) { reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value - 1); reg2->s32_min_value = max(reg1->s32_min_value + 1, reg2->s32_min_value); } else { reg1->smax_value = min(reg1->smax_value, reg2->smax_value - 1); reg2->smin_value = max(reg1->smin_value + 1, reg2->smin_value); } break; default: return; } } /* Adjusts the register min/max values in the case that the dst_reg and * src_reg are both SCALAR_VALUE registers (or we are simply doing a BPF_K * check, in which case we have a fake SCALAR_VALUE representing insn->imm). * Technically we can do similar adjustments for pointers to the same object, * but we don't support that right now. */ static int reg_set_min_max(struct bpf_verifier_env *env, struct bpf_reg_state *true_reg1, struct bpf_reg_state *true_reg2, struct bpf_reg_state *false_reg1, struct bpf_reg_state *false_reg2, u8 opcode, bool is_jmp32) { int err; /* If either register is a pointer, we can't learn anything about its * variable offset from the compare (unless they were a pointer into * the same object, but we don't bother with that). */ if (false_reg1->type != SCALAR_VALUE || false_reg2->type != SCALAR_VALUE) return 0; /* fallthrough (FALSE) branch */ regs_refine_cond_op(false_reg1, false_reg2, rev_opcode(opcode), is_jmp32); reg_bounds_sync(false_reg1); reg_bounds_sync(false_reg2); /* jump (TRUE) branch */ regs_refine_cond_op(true_reg1, true_reg2, opcode, is_jmp32); reg_bounds_sync(true_reg1); reg_bounds_sync(true_reg2); err = reg_bounds_sanity_check(env, true_reg1, "true_reg1"); err = err ?: reg_bounds_sanity_check(env, true_reg2, "true_reg2"); err = err ?: reg_bounds_sanity_check(env, false_reg1, "false_reg1"); err = err ?: reg_bounds_sanity_check(env, false_reg2, "false_reg2"); return err; } static void mark_ptr_or_null_reg(struct bpf_func_state *state, struct bpf_reg_state *reg, u32 id, bool is_null) { if (type_may_be_null(reg->type) && reg->id == id && (is_rcu_reg(reg) || !WARN_ON_ONCE(!reg->id))) { /* Old offset (both fixed and variable parts) should have been * known-zero, because we don't allow pointer arithmetic on * pointers that might be NULL. If we see this happening, don't * convert the register. * * But in some cases, some helpers that return local kptrs * advance offset for the returned pointer. In those cases, it * is fine to expect to see reg->off. */ if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || !tnum_equals_const(reg->var_off, 0))) return; if (!(type_is_ptr_alloc_obj(reg->type) || type_is_non_owning_ref(reg->type)) && WARN_ON_ONCE(reg->off)) return; if (is_null) { reg->type = SCALAR_VALUE; /* We don't need id and ref_obj_id from this point * onwards anymore, thus we should better reset it, * so that state pruning has chances to take effect. */ reg->id = 0; reg->ref_obj_id = 0; return; } mark_ptr_not_null_reg(reg); if (!reg_may_point_to_spin_lock(reg)) { /* For not-NULL ptr, reg->ref_obj_id will be reset * in release_reference(). * * reg->id is still used by spin_lock ptr. Other * than spin_lock ptr type, reg->id can be reset. */ reg->id = 0; } } } /* The logic is similar to find_good_pkt_pointers(), both could eventually * be folded together at some point. */ static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno, bool is_null) { struct bpf_func_state *state = vstate->frame[vstate->curframe]; struct bpf_reg_state *regs = state->regs, *reg; u32 ref_obj_id = regs[regno].ref_obj_id; u32 id = regs[regno].id; if (ref_obj_id && ref_obj_id == id && is_null) /* regs[regno] is in the " == NULL" branch. * No one could have freed the reference state before * doing the NULL check. */ WARN_ON_ONCE(release_reference_state(state, id)); bpf_for_each_reg_in_vstate(vstate, state, reg, ({ mark_ptr_or_null_reg(state, reg, id, is_null); })); } static bool try_match_pkt_pointers(const struct bpf_insn *insn, struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg, struct bpf_verifier_state *this_branch, struct bpf_verifier_state *other_branch) { if (BPF_SRC(insn->code) != BPF_X) return false; /* Pointers are always 64-bit. */ if (BPF_CLASS(insn->code) == BPF_JMP32) return false; switch (BPF_OP(insn->code)) { case BPF_JGT: if ((dst_reg->type == PTR_TO_PACKET && src_reg->type == PTR_TO_PACKET_END) || (dst_reg->type == PTR_TO_PACKET_META && reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { /* pkt_data' > pkt_end, pkt_meta' > pkt_data */ find_good_pkt_pointers(this_branch, dst_reg, dst_reg->type, false); mark_pkt_end(other_branch, insn->dst_reg, true); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && src_reg->type == PTR_TO_PACKET_META)) { /* pkt_end > pkt_data', pkt_data > pkt_meta' */ find_good_pkt_pointers(other_branch, src_reg, src_reg->type, true); mark_pkt_end(this_branch, insn->src_reg, false); } else { return false; } break; case BPF_JLT: if ((dst_reg->type == PTR_TO_PACKET && src_reg->type == PTR_TO_PACKET_END) || (dst_reg->type == PTR_TO_PACKET_META && reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { /* pkt_data' < pkt_end, pkt_meta' < pkt_data */ find_good_pkt_pointers(other_branch, dst_reg, dst_reg->type, true); mark_pkt_end(this_branch, insn->dst_reg, false); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && src_reg->type == PTR_TO_PACKET_META)) { /* pkt_end < pkt_data', pkt_data > pkt_meta' */ find_good_pkt_pointers(this_branch, src_reg, src_reg->type, false); mark_pkt_end(other_branch, insn->src_reg, true); } else { return false; } break; case BPF_JGE: if ((dst_reg->type == PTR_TO_PACKET && src_reg->type == PTR_TO_PACKET_END) || (dst_reg->type == PTR_TO_PACKET_META && reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */ find_good_pkt_pointers(this_branch, dst_reg, dst_reg->type, true); mark_pkt_end(other_branch, insn->dst_reg, false); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && src_reg->type == PTR_TO_PACKET_META)) { /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */ find_good_pkt_pointers(other_branch, src_reg, src_reg->type, false); mark_pkt_end(this_branch, insn->src_reg, true); } else { return false; } break; case BPF_JLE: if ((dst_reg->type == PTR_TO_PACKET && src_reg->type == PTR_TO_PACKET_END) || (dst_reg->type == PTR_TO_PACKET_META && reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */ find_good_pkt_pointers(other_branch, dst_reg, dst_reg->type, false); mark_pkt_end(this_branch, insn->dst_reg, true); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && src_reg->type == PTR_TO_PACKET_META)) { /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */ find_good_pkt_pointers(this_branch, src_reg, src_reg->type, true); mark_pkt_end(other_branch, insn->src_reg, false); } else { return false; } break; default: return false; } return true; } static void __collect_linked_regs(struct linked_regs *reg_set, struct bpf_reg_state *reg, u32 id, u32 frameno, u32 spi_or_reg, bool is_reg) { struct linked_reg *e; if (reg->type != SCALAR_VALUE || (reg->id & ~BPF_ADD_CONST) != id) return; e = linked_regs_push(reg_set); if (e) { e->frameno = frameno; e->is_reg = is_reg; e->regno = spi_or_reg; } else { reg->id = 0; } } /* For all R being scalar registers or spilled scalar registers * in verifier state, save R in linked_regs if R->id == id. * If there are too many Rs sharing same id, reset id for leftover Rs. */ static void collect_linked_regs(struct bpf_verifier_state *vstate, u32 id, struct linked_regs *linked_regs) { struct bpf_func_state *func; struct bpf_reg_state *reg; int i, j; id = id & ~BPF_ADD_CONST; for (i = vstate->curframe; i >= 0; i--) { func = vstate->frame[i]; for (j = 0; j < BPF_REG_FP; j++) { reg = &func->regs[j]; __collect_linked_regs(linked_regs, reg, id, i, j, true); } for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) { if (!is_spilled_reg(&func->stack[j])) continue; reg = &func->stack[j].spilled_ptr; __collect_linked_regs(linked_regs, reg, id, i, j, false); } } } /* For all R in linked_regs, copy known_reg range into R * if R->id == known_reg->id. */ static void sync_linked_regs(struct bpf_verifier_state *vstate, struct bpf_reg_state *known_reg, struct linked_regs *linked_regs) { struct bpf_reg_state fake_reg; struct bpf_reg_state *reg; struct linked_reg *e; int i; for (i = 0; i < linked_regs->cnt; ++i) { e = &linked_regs->entries[i]; reg = e->is_reg ? &vstate->frame[e->frameno]->regs[e->regno] : &vstate->frame[e->frameno]->stack[e->spi].spilled_ptr; if (reg->type != SCALAR_VALUE || reg == known_reg) continue; if ((reg->id & ~BPF_ADD_CONST) != (known_reg->id & ~BPF_ADD_CONST)) continue; if ((!(reg->id & BPF_ADD_CONST) && !(known_reg->id & BPF_ADD_CONST)) || reg->off == known_reg->off) { s32 saved_subreg_def = reg->subreg_def; copy_register_state(reg, known_reg); reg->subreg_def = saved_subreg_def; } else { s32 saved_subreg_def = reg->subreg_def; s32 saved_off = reg->off; fake_reg.type = SCALAR_VALUE; __mark_reg_known(&fake_reg, (s32)reg->off - (s32)known_reg->off); /* reg = known_reg; reg += delta */ copy_register_state(reg, known_reg); /* * Must preserve off, id and add_const flag, * otherwise another sync_linked_regs() will be incorrect. */ reg->off = saved_off; reg->subreg_def = saved_subreg_def; scalar32_min_max_add(reg, &fake_reg); scalar_min_max_add(reg, &fake_reg); reg->var_off = tnum_add(reg->var_off, fake_reg.var_off); } } } static int check_cond_jmp_op(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx) { struct bpf_verifier_state *this_branch = env->cur_state; struct bpf_verifier_state *other_branch; struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs; struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL; struct bpf_reg_state *eq_branch_regs; struct linked_regs linked_regs = {}; u8 opcode = BPF_OP(insn->code); bool is_jmp32; int pred = -1; int err; /* Only conditional jumps are expected to reach here. */ if (opcode == BPF_JA || opcode > BPF_JCOND) { verbose(env, "invalid BPF_JMP/JMP32 opcode %x\n", opcode); return -EINVAL; } if (opcode == BPF_JCOND) { struct bpf_verifier_state *cur_st = env->cur_state, *queued_st, *prev_st; int idx = *insn_idx; if (insn->code != (BPF_JMP | BPF_JCOND) || insn->src_reg != BPF_MAY_GOTO || insn->dst_reg || insn->imm || insn->off == 0) { verbose(env, "invalid may_goto off %d imm %d\n", insn->off, insn->imm); return -EINVAL; } prev_st = find_prev_entry(env, cur_st->parent, idx); /* branch out 'fallthrough' insn as a new state to explore */ queued_st = push_stack(env, idx + 1, idx, false); if (!queued_st) return -ENOMEM; queued_st->may_goto_depth++; if (prev_st) widen_imprecise_scalars(env, prev_st, queued_st); *insn_idx += insn->off; return 0; } /* check src2 operand */ err = check_reg_arg(env, insn->dst_reg, SRC_OP); if (err) return err; dst_reg = ®s[insn->dst_reg]; if (BPF_SRC(insn->code) == BPF_X) { if (insn->imm != 0) { verbose(env, "BPF_JMP/JMP32 uses reserved fields\n"); return -EINVAL; } /* check src1 operand */ err = check_reg_arg(env, insn->src_reg, SRC_OP); if (err) return err; src_reg = ®s[insn->src_reg]; if (!(reg_is_pkt_pointer_any(dst_reg) && reg_is_pkt_pointer_any(src_reg)) && is_pointer_value(env, insn->src_reg)) { verbose(env, "R%d pointer comparison prohibited\n", insn->src_reg); return -EACCES; } } else { if (insn->src_reg != BPF_REG_0) { verbose(env, "BPF_JMP/JMP32 uses reserved fields\n"); return -EINVAL; } src_reg = &env->fake_reg[0]; memset(src_reg, 0, sizeof(*src_reg)); src_reg->type = SCALAR_VALUE; __mark_reg_known(src_reg, insn->imm); } is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32; pred = is_branch_taken(dst_reg, src_reg, opcode, is_jmp32); if (pred >= 0) { /* If we get here with a dst_reg pointer type it is because * above is_branch_taken() special cased the 0 comparison. */ if (!__is_pointer_value(false, dst_reg)) err = mark_chain_precision(env, insn->dst_reg); if (BPF_SRC(insn->code) == BPF_X && !err && !__is_pointer_value(false, src_reg)) err = mark_chain_precision(env, insn->src_reg); if (err) return err; } if (pred == 1) { /* Only follow the goto, ignore fall-through. If needed, push * the fall-through branch for simulation under speculative * execution. */ if (!env->bypass_spec_v1 && !sanitize_speculative_path(env, insn, *insn_idx + 1, *insn_idx)) return -EFAULT; if (env->log.level & BPF_LOG_LEVEL) print_insn_state(env, this_branch->frame[this_branch->curframe]); *insn_idx += insn->off; return 0; } else if (pred == 0) { /* Only follow the fall-through branch, since that's where the * program will go. If needed, push the goto branch for * simulation under speculative execution. */ if (!env->bypass_spec_v1 && !sanitize_speculative_path(env, insn, *insn_idx + insn->off + 1, *insn_idx)) return -EFAULT; if (env->log.level & BPF_LOG_LEVEL) print_insn_state(env, this_branch->frame[this_branch->curframe]); return 0; } /* Push scalar registers sharing same ID to jump history, * do this before creating 'other_branch', so that both * 'this_branch' and 'other_branch' share this history * if parent state is created. */ if (BPF_SRC(insn->code) == BPF_X && src_reg->type == SCALAR_VALUE && src_reg->id) collect_linked_regs(this_branch, src_reg->id, &linked_regs); if (dst_reg->type == SCALAR_VALUE && dst_reg->id) collect_linked_regs(this_branch, dst_reg->id, &linked_regs); if (linked_regs.cnt > 1) { err = push_insn_history(env, this_branch, 0, linked_regs_pack(&linked_regs)); if (err) return err; } other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx, false); if (!other_branch) return -EFAULT; other_branch_regs = other_branch->frame[other_branch->curframe]->regs; if (BPF_SRC(insn->code) == BPF_X) { err = reg_set_min_max(env, &other_branch_regs[insn->dst_reg], &other_branch_regs[insn->src_reg], dst_reg, src_reg, opcode, is_jmp32); } else /* BPF_SRC(insn->code) == BPF_K */ { /* reg_set_min_max() can mangle the fake_reg. Make a copy * so that these are two different memory locations. The * src_reg is not used beyond here in context of K. */ memcpy(&env->fake_reg[1], &env->fake_reg[0], sizeof(env->fake_reg[0])); err = reg_set_min_max(env, &other_branch_regs[insn->dst_reg], &env->fake_reg[0], dst_reg, &env->fake_reg[1], opcode, is_jmp32); } if (err) return err; if (BPF_SRC(insn->code) == BPF_X && src_reg->type == SCALAR_VALUE && src_reg->id && !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) { sync_linked_regs(this_branch, src_reg, &linked_regs); sync_linked_regs(other_branch, &other_branch_regs[insn->src_reg], &linked_regs); } if (dst_reg->type == SCALAR_VALUE && dst_reg->id && !WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) { sync_linked_regs(this_branch, dst_reg, &linked_regs); sync_linked_regs(other_branch, &other_branch_regs[insn->dst_reg], &linked_regs); } /* if one pointer register is compared to another pointer * register check if PTR_MAYBE_NULL could be lifted. * E.g. register A - maybe null * register B - not null * for JNE A, B, ... - A is not null in the false branch; * for JEQ A, B, ... - A is not null in the true branch. * * Since PTR_TO_BTF_ID points to a kernel struct that does * not need to be null checked by the BPF program, i.e., * could be null even without PTR_MAYBE_NULL marking, so * only propagate nullness when neither reg is that type. */ if (!is_jmp32 && BPF_SRC(insn->code) == BPF_X && __is_pointer_value(false, src_reg) && __is_pointer_value(false, dst_reg) && type_may_be_null(src_reg->type) != type_may_be_null(dst_reg->type) && base_type(src_reg->type) != PTR_TO_BTF_ID && base_type(dst_reg->type) != PTR_TO_BTF_ID) { eq_branch_regs = NULL; switch (opcode) { case BPF_JEQ: eq_branch_regs = other_branch_regs; break; case BPF_JNE: eq_branch_regs = regs; break; default: /* do nothing */ break; } if (eq_branch_regs) { if (type_may_be_null(src_reg->type)) mark_ptr_not_null_reg(&eq_branch_regs[insn->src_reg]); else mark_ptr_not_null_reg(&eq_branch_regs[insn->dst_reg]); } } /* detect if R == 0 where R is returned from bpf_map_lookup_elem(). * NOTE: these optimizations below are related with pointer comparison * which will never be JMP32. */ if (!is_jmp32 && BPF_SRC(insn->code) == BPF_K && insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && type_may_be_null(dst_reg->type)) { /* Mark all identical registers in each branch as either * safe or unknown depending R == 0 or R != 0 conditional. */ mark_ptr_or_null_regs(this_branch, insn->dst_reg, opcode == BPF_JNE); mark_ptr_or_null_regs(other_branch, insn->dst_reg, opcode == BPF_JEQ); } else if (!try_match_pkt_pointers(insn, dst_reg, ®s[insn->src_reg], this_branch, other_branch) && is_pointer_value(env, insn->dst_reg)) { verbose(env, "R%d pointer comparison prohibited\n", insn->dst_reg); return -EACCES; } if (env->log.level & BPF_LOG_LEVEL) print_insn_state(env, this_branch->frame[this_branch->curframe]); return 0; } /* verify BPF_LD_IMM64 instruction */ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) { struct bpf_insn_aux_data *aux = cur_aux(env); struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *dst_reg; struct bpf_map *map; int err; if (BPF_SIZE(insn->code) != BPF_DW) { verbose(env, "invalid BPF_LD_IMM insn\n"); return -EINVAL; } if (insn->off != 0) { verbose(env, "BPF_LD_IMM64 uses reserved fields\n"); return -EINVAL; } err = check_reg_arg(env, insn->dst_reg, DST_OP); if (err) return err; dst_reg = ®s[insn->dst_reg]; if (insn->src_reg == 0) { u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; dst_reg->type = SCALAR_VALUE; __mark_reg_known(®s[insn->dst_reg], imm); return 0; } /* All special src_reg cases are listed below. From this point onwards * we either succeed and assign a corresponding dst_reg->type after * zeroing the offset, or fail and reject the program. */ mark_reg_known_zero(env, regs, insn->dst_reg); if (insn->src_reg == BPF_PSEUDO_BTF_ID) { dst_reg->type = aux->btf_var.reg_type; switch (base_type(dst_reg->type)) { case PTR_TO_MEM: dst_reg->mem_size = aux->btf_var.mem_size; break; case PTR_TO_BTF_ID: dst_reg->btf = aux->btf_var.btf; dst_reg->btf_id = aux->btf_var.btf_id; break; default: verbose(env, "bpf verifier is misconfigured\n"); return -EFAULT; } return 0; } if (insn->src_reg == BPF_PSEUDO_FUNC) { struct bpf_prog_aux *aux = env->prog->aux; u32 subprogno = find_subprog(env, env->insn_idx + insn->imm + 1); if (!aux->func_info) { verbose(env, "missing btf func_info\n"); return -EINVAL; } if (aux->func_info_aux[subprogno].linkage != BTF_FUNC_STATIC) { verbose(env, "callback function not static\n"); return -EINVAL; } dst_reg->type = PTR_TO_FUNC; dst_reg->subprogno = subprogno; return 0; } map = env->used_maps[aux->map_index]; dst_reg->map_ptr = map; if (insn->src_reg == BPF_PSEUDO_MAP_VALUE || insn->src_reg == BPF_PSEUDO_MAP_IDX_VALUE) { if (map->map_type == BPF_MAP_TYPE_ARENA) { __mark_reg_unknown(env, dst_reg); return 0; } dst_reg->type = PTR_TO_MAP_VALUE; dst_reg->off = aux->map_off; WARN_ON_ONCE(map->max_entries != 1); /* We want reg->id to be same (0) as map_value is not distinct */ } else if (insn->src_reg == BPF_PSEUDO_MAP_FD || insn->src_reg == BPF_PSEUDO_MAP_IDX) { dst_reg->type = CONST_PTR_TO_MAP; } else { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; } return 0; } static bool may_access_skb(enum bpf_prog_type type) { switch (type) { case BPF_PROG_TYPE_SOCKET_FILTER: case BPF_PROG_TYPE_SCHED_CLS: case BPF_PROG_TYPE_SCHED_ACT: return true; default: return false; } } /* verify safety of LD_ABS|LD_IND instructions: * - they can only appear in the programs where ctx == skb * - since they are wrappers of function calls, they scratch R1-R5 registers, * preserve R6-R9, and store return value into R0 * * Implicit input: * ctx == skb == R6 == CTX * * Explicit input: * SRC == any register * IMM == 32-bit immediate * * Output: * R0 - 8/16/32-bit skb data converted to cpu endianness */ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) { struct bpf_reg_state *regs = cur_regs(env); static const int ctx_reg = BPF_REG_6; u8 mode = BPF_MODE(insn->code); int i, err; if (!may_access_skb(resolve_prog_type(env->prog))) { verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); return -EINVAL; } if (!env->ops->gen_ld_abs) { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; } if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || BPF_SIZE(insn->code) == BPF_DW || (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n"); return -EINVAL; } /* check whether implicit source operand (register R6) is readable */ err = check_reg_arg(env, ctx_reg, SRC_OP); if (err) return err; /* Disallow usage of BPF_LD_[ABS|IND] with reference tracking, as * gen_ld_abs() may terminate the program at runtime, leading to * reference leak. */ err = check_resource_leak(env, false, true, "BPF_LD_[ABS|IND]"); if (err) return err; if (regs[ctx_reg].type != PTR_TO_CTX) { verbose(env, "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); return -EINVAL; } if (mode == BPF_IND) { /* check explicit source operand */ err = check_reg_arg(env, insn->src_reg, SRC_OP); if (err) return err; } err = check_ptr_off_reg(env, ®s[ctx_reg], ctx_reg); if (err < 0) return err; /* reset caller saved regs to unreadable */ for (i = 0; i < CALLER_SAVED_REGS; i++) { mark_reg_not_init(env, regs, caller_saved[i]); check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); } /* mark destination R0 register as readable, since it contains * the value fetched from the packet. * Already marked as written above. */ mark_reg_unknown(env, regs, BPF_REG_0); /* ld_abs load up to 32-bit skb data. */ regs[BPF_REG_0].subreg_def = env->insn_idx + 1; return 0; } static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name) { const char *exit_ctx = "At program exit"; struct tnum enforce_attach_type_range = tnum_unknown; const struct bpf_prog *prog = env->prog; struct bpf_reg_state *reg; struct bpf_retval_range range = retval_range(0, 1); enum bpf_prog_type prog_type = resolve_prog_type(env->prog); int err; struct bpf_func_state *frame = env->cur_state->frame[0]; const bool is_subprog = frame->subprogno; bool return_32bit = false; /* LSM and struct_ops func-ptr's return type could be "void" */ if (!is_subprog || frame->in_exception_callback_fn) { switch (prog_type) { case BPF_PROG_TYPE_LSM: if (prog->expected_attach_type == BPF_LSM_CGROUP) /* See below, can be 0 or 0-1 depending on hook. */ break; fallthrough; case BPF_PROG_TYPE_STRUCT_OPS: if (!prog->aux->attach_func_proto->type) return 0; break; default: break; } } /* eBPF calling convention is such that R0 is used * to return the value from eBPF program. * Make sure that it's readable at this time * of bpf_exit, which means that program wrote * something into it earlier */ err = check_reg_arg(env, regno, SRC_OP); if (err) return err; if (is_pointer_value(env, regno)) { verbose(env, "R%d leaks addr as return value\n", regno); return -EACCES; } reg = cur_regs(env) + regno; if (frame->in_async_callback_fn) { /* enforce return zero from async callbacks like timer */ exit_ctx = "At async callback return"; range = retval_range(0, 0); goto enforce_retval; } if (is_subprog && !frame->in_exception_callback_fn) { if (reg->type != SCALAR_VALUE) { verbose(env, "At subprogram exit the register R%d is not a scalar value (%s)\n", regno, reg_type_str(env, reg->type)); return -EINVAL; } return 0; } switch (prog_type) { case BPF_PROG_TYPE_CGROUP_SOCK_ADDR: if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG || env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG || env->prog->expected_attach_type == BPF_CGROUP_UNIX_RECVMSG || env->prog->expected_attach_type == BPF_CGROUP_INET4_GETPEERNAME || env->prog->expected_attach_type == BPF_CGROUP_INET6_GETPEERNAME || env->prog->expected_attach_type == BPF_CGROUP_UNIX_GETPEERNAME || env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME || env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME || env->prog->expected_attach_type == BPF_CGROUP_UNIX_GETSOCKNAME) range = retval_range(1, 1); if (env->prog->expected_attach_type == BPF_CGROUP_INET4_BIND || env->prog->expected_attach_type == BPF_CGROUP_INET6_BIND) range = retval_range(0, 3); break; case BPF_PROG_TYPE_CGROUP_SKB: if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) { range = retval_range(0, 3); enforce_attach_type_range = tnum_range(2, 3); } break; case BPF_PROG_TYPE_CGROUP_SOCK: case BPF_PROG_TYPE_SOCK_OPS: case BPF_PROG_TYPE_CGROUP_DEVICE: case BPF_PROG_TYPE_CGROUP_SYSCTL: case BPF_PROG_TYPE_CGROUP_SOCKOPT: break; case BPF_PROG_TYPE_RAW_TRACEPOINT: if (!env->prog->aux->attach_btf_id) return 0; range = retval_range(0, 0); break; case BPF_PROG_TYPE_TRACING: switch (env->prog->expected_attach_type) { case BPF_TRACE_FENTRY: case BPF_TRACE_FEXIT: range = retval_range(0, 0); break; case BPF_TRACE_RAW_TP: case BPF_MODIFY_RETURN: return 0; case BPF_TRACE_ITER: break; default: return -ENOTSUPP; } break; case BPF_PROG_TYPE_KPROBE: switch (env->prog->expected_attach_type) { case BPF_TRACE_KPROBE_SESSION: case BPF_TRACE_UPROBE_SESSION: range = retval_range(0, 1); break; default: return 0; } break; case BPF_PROG_TYPE_SK_LOOKUP: range = retval_range(SK_DROP, SK_PASS); break; case BPF_PROG_TYPE_LSM: if (env->prog->expected_attach_type != BPF_LSM_CGROUP) { /* no range found, any return value is allowed */ if (!get_func_retval_range(env->prog, &range)) return 0; /* no restricted range, any return value is allowed */ if (range.minval == S32_MIN && range.maxval == S32_MAX) return 0; return_32bit = true; } else if (!env->prog->aux->attach_func_proto->type) { /* Make sure programs that attach to void * hooks don't try to modify return value. */ range = retval_range(1, 1); } break; case BPF_PROG_TYPE_NETFILTER: range = retval_range(NF_DROP, NF_ACCEPT); break; case BPF_PROG_TYPE_EXT: /* freplace program can return anything as its return value * depends on the to-be-replaced kernel func or bpf program. */ default: return 0; } enforce_retval: if (reg->type != SCALAR_VALUE) { verbose(env, "%s the register R%d is not a known value (%s)\n", exit_ctx, regno, reg_type_str(env, reg->type)); return -EINVAL; } err = mark_chain_precision(env, regno); if (err) return err; if (!retval_range_within(range, reg, return_32bit)) { verbose_invalid_scalar(env, reg, range, exit_ctx, reg_name); if (!is_subprog && prog->expected_attach_type == BPF_LSM_CGROUP && prog_type == BPF_PROG_TYPE_LSM && !prog->aux->attach_func_proto->type) verbose(env, "Note, BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n"); return -EINVAL; } if (!tnum_is_unknown(enforce_attach_type_range) && tnum_in(enforce_attach_type_range, reg->var_off)) env->prog->enforce_expected_attach_type = 1; return 0; } static void mark_subprog_changes_pkt_data(struct bpf_verifier_env *env, int off) { struct bpf_subprog_info *subprog; subprog = find_containing_subprog(env, off); subprog->changes_pkt_data = true; } /* 't' is an index of a call-site. * 'w' is a callee entry point. * Eventually this function would be called when env->cfg.insn_state[w] == EXPLORED. * Rely on DFS traversal order and absence of recursive calls to guarantee that * callee's change_pkt_data marks would be correct at that moment. */ static void merge_callee_effects(struct bpf_verifier_env *env, int t, int w) { struct bpf_subprog_info *caller, *callee; caller = find_containing_subprog(env, t); callee = find_containing_subprog(env, w); caller->changes_pkt_data |= callee->changes_pkt_data; } /* non-recursive DFS pseudo code * 1 procedure DFS-iterative(G,v): * 2 label v as discovered * 3 let S be a stack * 4 S.push(v) * 5 while S is not empty * 6 t <- S.peek() * 7 if t is what we're looking for: * 8 return t * 9 for all edges e in G.adjacentEdges(t) do * 10 if edge e is already labelled * 11 continue with the next edge * 12 w <- G.adjacentVertex(t,e) * 13 if vertex w is not discovered and not explored * 14 label e as tree-edge * 15 label w as discovered * 16 S.push(w) * 17 continue at 5 * 18 else if vertex w is discovered * 19 label e as back-edge * 20 else * 21 // vertex w is explored * 22 label e as forward- or cross-edge * 23 label t as explored * 24 S.pop() * * convention: * 0x10 - discovered * 0x11 - discovered and fall-through edge labelled * 0x12 - discovered and fall-through and branch edges labelled * 0x20 - explored */ enum { DISCOVERED = 0x10, EXPLORED = 0x20, FALLTHROUGH = 1, BRANCH = 2, }; static void mark_prune_point(struct bpf_verifier_env *env, int idx) { env->insn_aux_data[idx].prune_point = true; } static bool is_prune_point(struct bpf_verifier_env *env, int insn_idx) { return env->insn_aux_data[insn_idx].prune_point; } static void mark_force_checkpoint(struct bpf_verifier_env *env, int idx) { env->insn_aux_data[idx].force_checkpoint = true; } static bool is_force_checkpoint(struct bpf_verifier_env *env, int insn_idx) { return env->insn_aux_data[insn_idx].force_checkpoint; } static void mark_calls_callback(struct bpf_verifier_env *env, int idx) { env->insn_aux_data[idx].calls_callback = true; } static bool calls_callback(struct bpf_verifier_env *env, int insn_idx) { return env->insn_aux_data[insn_idx].calls_callback; } enum { DONE_EXPLORING = 0, KEEP_EXPLORING = 1, }; /* t, w, e - match pseudo-code above: * t - index of current instruction * w - next instruction * e - edge */ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env) { int *insn_stack = env->cfg.insn_stack; int *insn_state = env->cfg.insn_state; if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) return DONE_EXPLORING; if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) return DONE_EXPLORING; if (w < 0 || w >= env->prog->len) { verbose_linfo(env, t, "%d: ", t); verbose(env, "jump out of range from insn %d to %d\n", t, w); return -EINVAL; } if (e == BRANCH) { /* mark branch target for state pruning */ mark_prune_point(env, w); mark_jmp_point(env, w); } if (insn_state[w] == 0) { /* tree-edge */ insn_state[t] = DISCOVERED | e; insn_state[w] = DISCOVERED; if (env->cfg.cur_stack >= env->prog->len) return -E2BIG; insn_stack[env->cfg.cur_stack++] = w; return KEEP_EXPLORING; } else if ((insn_state[w] & 0xF0) == DISCOVERED) { if (env->bpf_capable) return DONE_EXPLORING; verbose_linfo(env, t, "%d: ", t); verbose_linfo(env, w, "%d: ", w); verbose(env, "back-edge from insn %d to %d\n", t, w); return -EINVAL; } else if (insn_state[w] == EXPLORED) { /* forward- or cross-edge */ insn_state[t] = DISCOVERED | e; } else { verbose(env, "insn state internal bug\n"); return -EFAULT; } return DONE_EXPLORING; } static int visit_func_call_insn(int t, struct bpf_insn *insns, struct bpf_verifier_env *env, bool visit_callee) { int ret, insn_sz; int w; insn_sz = bpf_is_ldimm64(&insns[t]) ? 2 : 1; ret = push_insn(t, t + insn_sz, FALLTHROUGH, env); if (ret) return ret; mark_prune_point(env, t + insn_sz); /* when we exit from subprog, we need to record non-linear history */ mark_jmp_point(env, t + insn_sz); if (visit_callee) { w = t + insns[t].imm + 1; mark_prune_point(env, t); merge_callee_effects(env, t, w); ret = push_insn(t, w, BRANCH, env); } return ret; } /* Bitmask with 1s for all caller saved registers */ #define ALL_CALLER_SAVED_REGS ((1u << CALLER_SAVED_REGS) - 1) /* Return a bitmask specifying which caller saved registers are * clobbered by a call to a helper *as if* this helper follows * bpf_fastcall contract: * - includes R0 if function is non-void; * - includes R1-R5 if corresponding parameter has is described * in the function prototype. */ static u32 helper_fastcall_clobber_mask(const struct bpf_func_proto *fn) { u32 mask; int i; mask = 0; if (fn->ret_type != RET_VOID) mask |= BIT(BPF_REG_0); for (i = 0; i < ARRAY_SIZE(fn->arg_type); ++i) if (fn->arg_type[i] != ARG_DONTCARE) mask |= BIT(BPF_REG_1 + i); return mask; } /* True if do_misc_fixups() replaces calls to helper number 'imm', * replacement patch is presumed to follow bpf_fastcall contract * (see mark_fastcall_pattern_for_call() below). */ static bool verifier_inlines_helper_call(struct bpf_verifier_env *env, s32 imm) { switch (imm) { #ifdef CONFIG_X86_64 case BPF_FUNC_get_smp_processor_id: return env->prog->jit_requested && bpf_jit_supports_percpu_insn(); #endif default: return false; } } /* Same as helper_fastcall_clobber_mask() but for kfuncs, see comment above */ static u32 kfunc_fastcall_clobber_mask(struct bpf_kfunc_call_arg_meta *meta) { u32 vlen, i, mask; vlen = btf_type_vlen(meta->func_proto); mask = 0; if (!btf_type_is_void(btf_type_by_id(meta->btf, meta->func_proto->type))) mask |= BIT(BPF_REG_0); for (i = 0; i < vlen; ++i) mask |= BIT(BPF_REG_1 + i); return mask; } /* Same as verifier_inlines_helper_call() but for kfuncs, see comment above */ static bool is_fastcall_kfunc_call(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_FASTCALL; } /* LLVM define a bpf_fastcall function attribute. * This attribute means that function scratches only some of * the caller saved registers defined by ABI. * For BPF the set of such registers could be defined as follows: * - R0 is scratched only if function is non-void; * - R1-R5 are scratched only if corresponding parameter type is defined * in the function prototype. * * The contract between kernel and clang allows to simultaneously use * such functions and maintain backwards compatibility with old * kernels that don't understand bpf_fastcall calls: * * - for bpf_fastcall calls clang allocates registers as-if relevant r0-r5 * registers are not scratched by the call; * * - as a post-processing step, clang visits each bpf_fastcall call and adds * spill/fill for every live r0-r5; * * - stack offsets used for the spill/fill are allocated as lowest * stack offsets in whole function and are not used for any other * purposes; * * - when kernel loads a program, it looks for such patterns * (bpf_fastcall function surrounded by spills/fills) and checks if * spill/fill stack offsets are used exclusively in fastcall patterns; * * - if so, and if verifier or current JIT inlines the call to the * bpf_fastcall function (e.g. a helper call), kernel removes unnecessary * spill/fill pairs; * * - when old kernel loads a program, presence of spill/fill pairs * keeps BPF program valid, albeit slightly less efficient. * * For example: * * r1 = 1; * r2 = 2; * *(u64 *)(r10 - 8) = r1; r1 = 1; * *(u64 *)(r10 - 16) = r2; r2 = 2; * call %[to_be_inlined] --> call %[to_be_inlined] * r2 = *(u64 *)(r10 - 16); r0 = r1; * r1 = *(u64 *)(r10 - 8); r0 += r2; * r0 = r1; exit; * r0 += r2; * exit; * * The purpose of mark_fastcall_pattern_for_call is to: * - look for such patterns; * - mark spill and fill instructions in env->insn_aux_data[*].fastcall_pattern; * - mark set env->insn_aux_data[*].fastcall_spills_num for call instruction; * - update env->subprog_info[*]->fastcall_stack_off to find an offset * at which bpf_fastcall spill/fill stack slots start; * - update env->subprog_info[*]->keep_fastcall_stack. * * The .fastcall_pattern and .fastcall_stack_off are used by * check_fastcall_stack_contract() to check if every stack access to * fastcall spill/fill stack slot originates from spill/fill * instructions, members of fastcall patterns. * * If such condition holds true for a subprogram, fastcall patterns could * be rewritten by remove_fastcall_spills_fills(). * Otherwise bpf_fastcall patterns are not changed in the subprogram * (code, presumably, generated by an older clang version). * * For example, it is *not* safe to remove spill/fill below: * * r1 = 1; * *(u64 *)(r10 - 8) = r1; r1 = 1; * call %[to_be_inlined] --> call %[to_be_inlined] * r1 = *(u64 *)(r10 - 8); r0 = *(u64 *)(r10 - 8); <---- wrong !!! * r0 = *(u64 *)(r10 - 8); r0 += r1; * r0 += r1; exit; * exit; */ static void mark_fastcall_pattern_for_call(struct bpf_verifier_env *env, struct bpf_subprog_info *subprog, int insn_idx, s16 lowest_off) { struct bpf_insn *insns = env->prog->insnsi, *stx, *ldx; struct bpf_insn *call = &env->prog->insnsi[insn_idx]; const struct bpf_func_proto *fn; u32 clobbered_regs_mask = ALL_CALLER_SAVED_REGS; u32 expected_regs_mask; bool can_be_inlined = false; s16 off; int i; if (bpf_helper_call(call)) { if (get_helper_proto(env, call->imm, &fn) < 0) /* error would be reported later */ return; clobbered_regs_mask = helper_fastcall_clobber_mask(fn); can_be_inlined = fn->allow_fastcall && (verifier_inlines_helper_call(env, call->imm) || bpf_jit_inlines_helper_call(call->imm)); } if (bpf_pseudo_kfunc_call(call)) { struct bpf_kfunc_call_arg_meta meta; int err; err = fetch_kfunc_meta(env, call, &meta, NULL); if (err < 0) /* error would be reported later */ return; clobbered_regs_mask = kfunc_fastcall_clobber_mask(&meta); can_be_inlined = is_fastcall_kfunc_call(&meta); } if (clobbered_regs_mask == ALL_CALLER_SAVED_REGS) return; /* e.g. if helper call clobbers r{0,1}, expect r{2,3,4,5} in the pattern */ expected_regs_mask = ~clobbered_regs_mask & ALL_CALLER_SAVED_REGS; /* match pairs of form: * * *(u64 *)(r10 - Y) = rX (where Y % 8 == 0) * ... * call %[to_be_inlined] * ... * rX = *(u64 *)(r10 - Y) */ for (i = 1, off = lowest_off; i <= ARRAY_SIZE(caller_saved); ++i, off += BPF_REG_SIZE) { if (insn_idx - i < 0 || insn_idx + i >= env->prog->len) break; stx = &insns[insn_idx - i]; ldx = &insns[insn_idx + i]; /* must be a stack spill/fill pair */ if (stx->code != (BPF_STX | BPF_MEM | BPF_DW) || ldx->code != (BPF_LDX | BPF_MEM | BPF_DW) || stx->dst_reg != BPF_REG_10 || ldx->src_reg != BPF_REG_10) break; /* must be a spill/fill for the same reg */ if (stx->src_reg != ldx->dst_reg) break; /* must be one of the previously unseen registers */ if ((BIT(stx->src_reg) & expected_regs_mask) == 0) break; /* must be a spill/fill for the same expected offset, * no need to check offset alignment, BPF_DW stack access * is always 8-byte aligned. */ if (stx->off != off || ldx->off != off) break; expected_regs_mask &= ~BIT(stx->src_reg); env->insn_aux_data[insn_idx - i].fastcall_pattern = 1; env->insn_aux_data[insn_idx + i].fastcall_pattern = 1; } if (i == 1) return; /* Conditionally set 'fastcall_spills_num' to allow forward * compatibility when more helper functions are marked as * bpf_fastcall at compile time than current kernel supports, e.g: * * 1: *(u64 *)(r10 - 8) = r1 * 2: call A ;; assume A is bpf_fastcall for current kernel * 3: r1 = *(u64 *)(r10 - 8) * 4: *(u64 *)(r10 - 8) = r1 * 5: call B ;; assume B is not bpf_fastcall for current kernel * 6: r1 = *(u64 *)(r10 - 8) * * There is no need to block bpf_fastcall rewrite for such program. * Set 'fastcall_pattern' for both calls to keep check_fastcall_stack_contract() happy, * don't set 'fastcall_spills_num' for call B so that remove_fastcall_spills_fills() * does not remove spill/fill pair {4,6}. */ if (can_be_inlined) env->insn_aux_data[insn_idx].fastcall_spills_num = i - 1; else subprog->keep_fastcall_stack = 1; subprog->fastcall_stack_off = min(subprog->fastcall_stack_off, off); } static int mark_fastcall_patterns(struct bpf_verifier_env *env) { struct bpf_subprog_info *subprog = env->subprog_info; struct bpf_insn *insn; s16 lowest_off; int s, i; for (s = 0; s < env->subprog_cnt; ++s, ++subprog) { /* find lowest stack spill offset used in this subprog */ lowest_off = 0; for (i = subprog->start; i < (subprog + 1)->start; ++i) { insn = env->prog->insnsi + i; if (insn->code != (BPF_STX | BPF_MEM | BPF_DW) || insn->dst_reg != BPF_REG_10) continue; lowest_off = min(lowest_off, insn->off); } /* use this offset to find fastcall patterns */ for (i = subprog->start; i < (subprog + 1)->start; ++i) { insn = env->prog->insnsi + i; if (insn->code != (BPF_JMP | BPF_CALL)) continue; mark_fastcall_pattern_for_call(env, subprog, i, lowest_off); } } return 0; } /* Visits the instruction at index t and returns one of the following: * < 0 - an error occurred * DONE_EXPLORING - the instruction was fully explored * KEEP_EXPLORING - there is still work to be done before it is fully explored */ static int visit_insn(int t, struct bpf_verifier_env *env) { struct bpf_insn *insns = env->prog->insnsi, *insn = &insns[t]; int ret, off, insn_sz; if (bpf_pseudo_func(insn)) return visit_func_call_insn(t, insns, env, true); /* All non-branch instructions have a single fall-through edge. */ if (BPF_CLASS(insn->code) != BPF_JMP && BPF_CLASS(insn->code) != BPF_JMP32) { insn_sz = bpf_is_ldimm64(insn) ? 2 : 1; return push_insn(t, t + insn_sz, FALLTHROUGH, env); } switch (BPF_OP(insn->code)) { case BPF_EXIT: return DONE_EXPLORING; case BPF_CALL: if (is_async_callback_calling_insn(insn)) /* Mark this call insn as a prune point to trigger * is_state_visited() check before call itself is * processed by __check_func_call(). Otherwise new * async state will be pushed for further exploration. */ mark_prune_point(env, t); /* For functions that invoke callbacks it is not known how many times * callback would be called. Verifier models callback calling functions * by repeatedly visiting callback bodies and returning to origin call * instruction. * In order to stop such iteration verifier needs to identify when a * state identical some state from a previous iteration is reached. * Check below forces creation of checkpoint before callback calling * instruction to allow search for such identical states. */ if (is_sync_callback_calling_insn(insn)) { mark_calls_callback(env, t); mark_force_checkpoint(env, t); mark_prune_point(env, t); mark_jmp_point(env, t); } if (bpf_helper_call(insn) && bpf_helper_changes_pkt_data(insn->imm)) mark_subprog_changes_pkt_data(env, t); if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { struct bpf_kfunc_call_arg_meta meta; ret = fetch_kfunc_meta(env, insn, &meta, NULL); if (ret == 0 && is_iter_next_kfunc(&meta)) { mark_prune_point(env, t); /* Checking and saving state checkpoints at iter_next() call * is crucial for fast convergence of open-coded iterator loop * logic, so we need to force it. If we don't do that, * is_state_visited() might skip saving a checkpoint, causing * unnecessarily long sequence of not checkpointed * instructions and jumps, leading to exhaustion of jump * history buffer, and potentially other undesired outcomes. * It is expected that with correct open-coded iterators * convergence will happen quickly, so we don't run a risk of * exhausting memory. */ mark_force_checkpoint(env, t); } } return visit_func_call_insn(t, insns, env, insn->src_reg == BPF_PSEUDO_CALL); case BPF_JA: if (BPF_SRC(insn->code) != BPF_K) return -EINVAL; if (BPF_CLASS(insn->code) == BPF_JMP) off = insn->off; else off = insn->imm; /* unconditional jump with single edge */ ret = push_insn(t, t + off + 1, FALLTHROUGH, env); if (ret) return ret; mark_prune_point(env, t + off + 1); mark_jmp_point(env, t + off + 1); return ret; default: /* conditional jump with two edges */ mark_prune_point(env, t); if (is_may_goto_insn(insn)) mark_force_checkpoint(env, t); ret = push_insn(t, t + 1, FALLTHROUGH, env); if (ret) return ret; return push_insn(t, t + insn->off + 1, BRANCH, env); } } /* non-recursive depth-first-search to detect loops in BPF program * loop == back-edge in directed graph */ static int check_cfg(struct bpf_verifier_env *env) { int insn_cnt = env->prog->len; int *insn_stack, *insn_state; int ex_insn_beg, i, ret = 0; bool ex_done = false; insn_state = env->cfg.insn_state = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL); if (!insn_state) return -ENOMEM; insn_stack = env->cfg.insn_stack = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL); if (!insn_stack) { kvfree(insn_state); return -ENOMEM; } insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ insn_stack[0] = 0; /* 0 is the first instruction */ env->cfg.cur_stack = 1; walk_cfg: while (env->cfg.cur_stack > 0) { int t = insn_stack[env->cfg.cur_stack - 1]; ret = visit_insn(t, env); switch (ret) { case DONE_EXPLORING: insn_state[t] = EXPLORED; env->cfg.cur_stack--; break; case KEEP_EXPLORING: break; default: if (ret > 0) { verbose(env, "visit_insn internal bug\n"); ret = -EFAULT; } goto err_free; } } if (env->cfg.cur_stack < 0) { verbose(env, "pop stack internal bug\n"); ret = -EFAULT; goto err_free; } if (env->exception_callback_subprog && !ex_done) { ex_insn_beg = env->subprog_info[env->exception_callback_subprog].start; insn_state[ex_insn_beg] = DISCOVERED; insn_stack[0] = ex_insn_beg; env->cfg.cur_stack = 1; ex_done = true; goto walk_cfg; } for (i = 0; i < insn_cnt; i++) { struct bpf_insn *insn = &env->prog->insnsi[i]; if (insn_state[i] != EXPLORED) { verbose(env, "unreachable insn %d\n", i); ret = -EINVAL; goto err_free; } if (bpf_is_ldimm64(insn)) { if (insn_state[i + 1] != 0) { verbose(env, "jump into the middle of ldimm64 insn %d\n", i); ret = -EINVAL; goto err_free; } i++; /* skip second half of ldimm64 */ } } ret = 0; /* cfg looks good */ env->prog->aux->changes_pkt_data = env->subprog_info[0].changes_pkt_data; err_free: kvfree(insn_state); kvfree(insn_stack); env->cfg.insn_state = env->cfg.insn_stack = NULL; return ret; } static int check_abnormal_return(struct bpf_verifier_env *env) { int i; for (i = 1; i < env->subprog_cnt; i++) { if (env->subprog_info[i].has_ld_abs) { verbose(env, "LD_ABS is not allowed in subprogs without BTF\n"); return -EINVAL; } if (env->subprog_info[i].has_tail_call) { verbose(env, "tail_call is not allowed in subprogs without BTF\n"); return -EINVAL; } } return 0; } /* The minimum supported BTF func info size */ #define MIN_BPF_FUNCINFO_SIZE 8 #define MAX_FUNCINFO_REC_SIZE 252 static int check_btf_func_early(struct bpf_verifier_env *env, const union bpf_attr *attr, bpfptr_t uattr) { u32 krec_size = sizeof(struct bpf_func_info); const struct btf_type *type, *func_proto; u32 i, nfuncs, urec_size, min_size; struct bpf_func_info *krecord; struct bpf_prog *prog; const struct btf *btf; u32 prev_offset = 0; bpfptr_t urecord; int ret = -ENOMEM; nfuncs = attr->func_info_cnt; if (!nfuncs) { if (check_abnormal_return(env)) return -EINVAL; return 0; } urec_size = attr->func_info_rec_size; if (urec_size < MIN_BPF_FUNCINFO_SIZE || urec_size > MAX_FUNCINFO_REC_SIZE || urec_size % sizeof(u32)) { verbose(env, "invalid func info rec size %u\n", urec_size); return -EINVAL; } prog = env->prog; btf = prog->aux->btf; urecord = make_bpfptr(attr->func_info, uattr.is_kernel); min_size = min_t(u32, krec_size, urec_size); krecord = kvcalloc(nfuncs, krec_size, GFP_KERNEL | __GFP_NOWARN); if (!krecord) return -ENOMEM; for (i = 0; i < nfuncs; i++) { ret = bpf_check_uarg_tail_zero(urecord, krec_size, urec_size); if (ret) { if (ret == -E2BIG) { verbose(env, "nonzero tailing record in func info"); /* set the size kernel expects so loader can zero * out the rest of the record. */ if (copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, func_info_rec_size), &min_size, sizeof(min_size))) ret = -EFAULT; } goto err_free; } if (copy_from_bpfptr(&krecord[i], urecord, min_size)) { ret = -EFAULT; goto err_free; } /* check insn_off */ ret = -EINVAL; if (i == 0) { if (krecord[i].insn_off) { verbose(env, "nonzero insn_off %u for the first func info record", krecord[i].insn_off); goto err_free; } } else if (krecord[i].insn_off <= prev_offset) { verbose(env, "same or smaller insn offset (%u) than previous func info record (%u)", krecord[i].insn_off, prev_offset); goto err_free; } /* check type_id */ type = btf_type_by_id(btf, krecord[i].type_id); if (!type || !btf_type_is_func(type)) { verbose(env, "invalid type id %d in func info", krecord[i].type_id); goto err_free; } func_proto = btf_type_by_id(btf, type->type); if (unlikely(!func_proto || !btf_type_is_func_proto(func_proto))) /* btf_func_check() already verified it during BTF load */ goto err_free; prev_offset = krecord[i].insn_off; bpfptr_add(&urecord, urec_size); } prog->aux->func_info = krecord; prog->aux->func_info_cnt = nfuncs; return 0; err_free: kvfree(krecord); return ret; } static int check_btf_func(struct bpf_verifier_env *env, const union bpf_attr *attr, bpfptr_t uattr) { const struct btf_type *type, *func_proto, *ret_type; u32 i, nfuncs, urec_size; struct bpf_func_info *krecord; struct bpf_func_info_aux *info_aux = NULL; struct bpf_prog *prog; const struct btf *btf; bpfptr_t urecord; bool scalar_return; int ret = -ENOMEM; nfuncs = attr->func_info_cnt; if (!nfuncs) { if (check_abnormal_return(env)) return -EINVAL; return 0; } if (nfuncs != env->subprog_cnt) { verbose(env, "number of funcs in func_info doesn't match number of subprogs\n"); return -EINVAL; } urec_size = attr->func_info_rec_size; prog = env->prog; btf = prog->aux->btf; urecord = make_bpfptr(attr->func_info, uattr.is_kernel); krecord = prog->aux->func_info; info_aux = kcalloc(nfuncs, sizeof(*info_aux), GFP_KERNEL | __GFP_NOWARN); if (!info_aux) return -ENOMEM; for (i = 0; i < nfuncs; i++) { /* check insn_off */ ret = -EINVAL; if (env->subprog_info[i].start != krecord[i].insn_off) { verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n"); goto err_free; } /* Already checked type_id */ type = btf_type_by_id(btf, krecord[i].type_id); info_aux[i].linkage = BTF_INFO_VLEN(type->info); /* Already checked func_proto */ func_proto = btf_type_by_id(btf, type->type); ret_type = btf_type_skip_modifiers(btf, func_proto->type, NULL); scalar_return = btf_type_is_small_int(ret_type) || btf_is_any_enum(ret_type); if (i && !scalar_return && env->subprog_info[i].has_ld_abs) { verbose(env, "LD_ABS is only allowed in functions that return 'int'.\n"); goto err_free; } if (i && !scalar_return && env->subprog_info[i].has_tail_call) { verbose(env, "tail_call is only allowed in functions that return 'int'.\n"); goto err_free; } bpfptr_add(&urecord, urec_size); } prog->aux->func_info_aux = info_aux; return 0; err_free: kfree(info_aux); return ret; } static void adjust_btf_func(struct bpf_verifier_env *env) { struct bpf_prog_aux *aux = env->prog->aux; int i; if (!aux->func_info) return; /* func_info is not available for hidden subprogs */ for (i = 0; i < env->subprog_cnt - env->hidden_subprog_cnt; i++) aux->func_info[i].insn_off = env->subprog_info[i].start; } #define MIN_BPF_LINEINFO_SIZE offsetofend(struct bpf_line_info, line_col) #define MAX_LINEINFO_REC_SIZE MAX_FUNCINFO_REC_SIZE static int check_btf_line(struct bpf_verifier_env *env, const union bpf_attr *attr, bpfptr_t uattr) { u32 i, s, nr_linfo, ncopy, expected_size, rec_size, prev_offset = 0; struct bpf_subprog_info *sub; struct bpf_line_info *linfo; struct bpf_prog *prog; const struct btf *btf; bpfptr_t ulinfo; int err; nr_linfo = attr->line_info_cnt; if (!nr_linfo) return 0; if (nr_linfo > INT_MAX / sizeof(struct bpf_line_info)) return -EINVAL; rec_size = attr->line_info_rec_size; if (rec_size < MIN_BPF_LINEINFO_SIZE || rec_size > MAX_LINEINFO_REC_SIZE || rec_size & (sizeof(u32) - 1)) return -EINVAL; /* Need to zero it in case the userspace may * pass in a smaller bpf_line_info object. */ linfo = kvcalloc(nr_linfo, sizeof(struct bpf_line_info), GFP_KERNEL | __GFP_NOWARN); if (!linfo) return -ENOMEM; prog = env->prog; btf = prog->aux->btf; s = 0; sub = env->subprog_info; ulinfo = make_bpfptr(attr->line_info, uattr.is_kernel); expected_size = sizeof(struct bpf_line_info); ncopy = min_t(u32, expected_size, rec_size); for (i = 0; i < nr_linfo; i++) { err = bpf_check_uarg_tail_zero(ulinfo, expected_size, rec_size); if (err) { if (err == -E2BIG) { verbose(env, "nonzero tailing record in line_info"); if (copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, line_info_rec_size), &expected_size, sizeof(expected_size))) err = -EFAULT; } goto err_free; } if (copy_from_bpfptr(&linfo[i], ulinfo, ncopy)) { err = -EFAULT; goto err_free; } /* * Check insn_off to ensure * 1) strictly increasing AND * 2) bounded by prog->len * * The linfo[0].insn_off == 0 check logically falls into * the later "missing bpf_line_info for func..." case * because the first linfo[0].insn_off must be the * first sub also and the first sub must have * subprog_info[0].start == 0. */ if ((i && linfo[i].insn_off <= prev_offset) || linfo[i].insn_off >= prog->len) { verbose(env, "Invalid line_info[%u].insn_off:%u (prev_offset:%u prog->len:%u)\n", i, linfo[i].insn_off, prev_offset, prog->len); err = -EINVAL; goto err_free; } if (!prog->insnsi[linfo[i].insn_off].code) { verbose(env, "Invalid insn code at line_info[%u].insn_off\n", i); err = -EINVAL; goto err_free; } if (!btf_name_by_offset(btf, linfo[i].line_off) || !btf_name_by_offset(btf, linfo[i].file_name_off)) { verbose(env, "Invalid line_info[%u].line_off or .file_name_off\n", i); err = -EINVAL; goto err_free; } if (s != env->subprog_cnt) { if (linfo[i].insn_off == sub[s].start) { sub[s].linfo_idx = i; s++; } else if (sub[s].start < linfo[i].insn_off) { verbose(env, "missing bpf_line_info for func#%u\n", s); err = -EINVAL; goto err_free; } } prev_offset = linfo[i].insn_off; bpfptr_add(&ulinfo, rec_size); } if (s != env->subprog_cnt) { verbose(env, "missing bpf_line_info for %u funcs starting from func#%u\n", env->subprog_cnt - s, s); err = -EINVAL; goto err_free; } prog->aux->linfo = linfo; prog->aux->nr_linfo = nr_linfo; return 0; err_free: kvfree(linfo); return err; } #define MIN_CORE_RELO_SIZE sizeof(struct bpf_core_relo) #define MAX_CORE_RELO_SIZE MAX_FUNCINFO_REC_SIZE static int check_core_relo(struct bpf_verifier_env *env, const union bpf_attr *attr, bpfptr_t uattr) { u32 i, nr_core_relo, ncopy, expected_size, rec_size; struct bpf_core_relo core_relo = {}; struct bpf_prog *prog = env->prog; const struct btf *btf = prog->aux->btf; struct bpf_core_ctx ctx = { .log = &env->log, .btf = btf, }; bpfptr_t u_core_relo; int err; nr_core_relo = attr->core_relo_cnt; if (!nr_core_relo) return 0; if (nr_core_relo > INT_MAX / sizeof(struct bpf_core_relo)) return -EINVAL; rec_size = attr->core_relo_rec_size; if (rec_size < MIN_CORE_RELO_SIZE || rec_size > MAX_CORE_RELO_SIZE || rec_size % sizeof(u32)) return -EINVAL; u_core_relo = make_bpfptr(attr->core_relos, uattr.is_kernel); expected_size = sizeof(struct bpf_core_relo); ncopy = min_t(u32, expected_size, rec_size); /* Unlike func_info and line_info, copy and apply each CO-RE * relocation record one at a time. */ for (i = 0; i < nr_core_relo; i++) { /* future proofing when sizeof(bpf_core_relo) changes */ err = bpf_check_uarg_tail_zero(u_core_relo, expected_size, rec_size); if (err) { if (err == -E2BIG) { verbose(env, "nonzero tailing record in core_relo"); if (copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, core_relo_rec_size), &expected_size, sizeof(expected_size))) err = -EFAULT; } break; } if (copy_from_bpfptr(&core_relo, u_core_relo, ncopy)) { err = -EFAULT; break; } if (core_relo.insn_off % 8 || core_relo.insn_off / 8 >= prog->len) { verbose(env, "Invalid core_relo[%u].insn_off:%u prog->len:%u\n", i, core_relo.insn_off, prog->len); err = -EINVAL; break; } err = bpf_core_apply(&ctx, &core_relo, i, &prog->insnsi[core_relo.insn_off / 8]); if (err) break; bpfptr_add(&u_core_relo, rec_size); } return err; } static int check_btf_info_early(struct bpf_verifier_env *env, const union bpf_attr *attr, bpfptr_t uattr) { struct btf *btf; int err; if (!attr->func_info_cnt && !attr->line_info_cnt) { if (check_abnormal_return(env)) return -EINVAL; return 0; } btf = btf_get_by_fd(attr->prog_btf_fd); if (IS_ERR(btf)) return PTR_ERR(btf); if (btf_is_kernel(btf)) { btf_put(btf); return -EACCES; } env->prog->aux->btf = btf; err = check_btf_func_early(env, attr, uattr); if (err) return err; return 0; } static int check_btf_info(struct bpf_verifier_env *env, const union bpf_attr *attr, bpfptr_t uattr) { int err; if (!attr->func_info_cnt && !attr->line_info_cnt) { if (check_abnormal_return(env)) return -EINVAL; return 0; } err = check_btf_func(env, attr, uattr); if (err) return err; err = check_btf_line(env, attr, uattr); if (err) return err; err = check_core_relo(env, attr, uattr); if (err) return err; return 0; } /* check %cur's range satisfies %old's */ static bool range_within(const struct bpf_reg_state *old, const struct bpf_reg_state *cur) { return old->umin_value <= cur->umin_value && old->umax_value >= cur->umax_value && old->smin_value <= cur->smin_value && old->smax_value >= cur->smax_value && old->u32_min_value <= cur->u32_min_value && old->u32_max_value >= cur->u32_max_value && old->s32_min_value <= cur->s32_min_value && old->s32_max_value >= cur->s32_max_value; } /* If in the old state two registers had the same id, then they need to have * the same id in the new state as well. But that id could be different from * the old state, so we need to track the mapping from old to new ids. * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent * regs with old id 5 must also have new id 9 for the new state to be safe. But * regs with a different old id could still have new id 9, we don't care about * that. * So we look through our idmap to see if this old id has been seen before. If * so, we require the new id to match; otherwise, we add the id pair to the map. */ static bool check_ids(u32 old_id, u32 cur_id, struct bpf_idmap *idmap) { struct bpf_id_pair *map = idmap->map; unsigned int i; /* either both IDs should be set or both should be zero */ if (!!old_id != !!cur_id) return false; if (old_id == 0) /* cur_id == 0 as well */ return true; for (i = 0; i < BPF_ID_MAP_SIZE; i++) { if (!map[i].old) { /* Reached an empty slot; haven't seen this id before */ map[i].old = old_id; map[i].cur = cur_id; return true; } if (map[i].old == old_id) return map[i].cur == cur_id; if (map[i].cur == cur_id) return false; } /* We ran out of idmap slots, which should be impossible */ WARN_ON_ONCE(1); return false; } /* Similar to check_ids(), but allocate a unique temporary ID * for 'old_id' or 'cur_id' of zero. * This makes pairs like '0 vs unique ID', 'unique ID vs 0' valid. */ static bool check_scalar_ids(u32 old_id, u32 cur_id, struct bpf_idmap *idmap) { old_id = old_id ? old_id : ++idmap->tmp_id_gen; cur_id = cur_id ? cur_id : ++idmap->tmp_id_gen; return check_ids(old_id, cur_id, idmap); } static void clean_func_state(struct bpf_verifier_env *env, struct bpf_func_state *st) { enum bpf_reg_liveness live; int i, j; for (i = 0; i < BPF_REG_FP; i++) { live = st->regs[i].live; /* liveness must not touch this register anymore */ st->regs[i].live |= REG_LIVE_DONE; if (!(live & REG_LIVE_READ)) /* since the register is unused, clear its state * to make further comparison simpler */ __mark_reg_not_init(env, &st->regs[i]); } for (i = 0; i < st->allocated_stack / BPF_REG_SIZE; i++) { live = st->stack[i].spilled_ptr.live; /* liveness must not touch this stack slot anymore */ st->stack[i].spilled_ptr.live |= REG_LIVE_DONE; if (!(live & REG_LIVE_READ)) { __mark_reg_not_init(env, &st->stack[i].spilled_ptr); for (j = 0; j < BPF_REG_SIZE; j++) st->stack[i].slot_type[j] = STACK_INVALID; } } } static void clean_verifier_state(struct bpf_verifier_env *env, struct bpf_verifier_state *st) { int i; if (st->frame[0]->regs[0].live & REG_LIVE_DONE) /* all regs in this state in all frames were already marked */ return; for (i = 0; i <= st->curframe; i++) clean_func_state(env, st->frame[i]); } /* the parentage chains form a tree. * the verifier states are added to state lists at given insn and * pushed into state stack for future exploration. * when the verifier reaches bpf_exit insn some of the verifer states * stored in the state lists have their final liveness state already, * but a lot of states will get revised from liveness point of view when * the verifier explores other branches. * Example: * 1: r0 = 1 * 2: if r1 == 100 goto pc+1 * 3: r0 = 2 * 4: exit * when the verifier reaches exit insn the register r0 in the state list of * insn 2 will be seen as !REG_LIVE_READ. Then the verifier pops the other_branch * of insn 2 and goes exploring further. At the insn 4 it will walk the * parentage chain from insn 4 into insn 2 and will mark r0 as REG_LIVE_READ. * * Since the verifier pushes the branch states as it sees them while exploring * the program the condition of walking the branch instruction for the second * time means that all states below this branch were already explored and * their final liveness marks are already propagated. * Hence when the verifier completes the search of state list in is_state_visited() * we can call this clean_live_states() function to mark all liveness states * as REG_LIVE_DONE to indicate that 'parent' pointers of 'struct bpf_reg_state' * will not be used. * This function also clears the registers and stack for states that !READ * to simplify state merging. * * Important note here that walking the same branch instruction in the callee * doesn't meant that the states are DONE. The verifier has to compare * the callsites */ static void clean_live_states(struct bpf_verifier_env *env, int insn, struct bpf_verifier_state *cur) { struct bpf_verifier_state_list *sl; sl = *explored_state(env, insn); while (sl) { if (sl->state.branches) goto next; if (sl->state.insn_idx != insn || !same_callsites(&sl->state, cur)) goto next; clean_verifier_state(env, &sl->state); next: sl = sl->next; } } static bool regs_exact(const struct bpf_reg_state *rold, const struct bpf_reg_state *rcur, struct bpf_idmap *idmap) { return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && check_ids(rold->id, rcur->id, idmap) && check_ids(rold->ref_obj_id, rcur->ref_obj_id, idmap); } enum exact_level { NOT_EXACT, EXACT, RANGE_WITHIN }; /* Returns true if (rold safe implies rcur safe) */ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, struct bpf_reg_state *rcur, struct bpf_idmap *idmap, enum exact_level exact) { if (exact == EXACT) return regs_exact(rold, rcur, idmap); if (!(rold->live & REG_LIVE_READ) && exact == NOT_EXACT) /* explored state didn't use this */ return true; if (rold->type == NOT_INIT) { if (exact == NOT_EXACT || rcur->type == NOT_INIT) /* explored state can't have used this */ return true; } /* Enforce that register types have to match exactly, including their * modifiers (like PTR_MAYBE_NULL, MEM_RDONLY, etc), as a general * rule. * * One can make a point that using a pointer register as unbounded * SCALAR would be technically acceptable, but this could lead to * pointer leaks because scalars are allowed to leak while pointers * are not. We could make this safe in special cases if root is * calling us, but it's probably not worth the hassle. * * Also, register types that are *not* MAYBE_NULL could technically be * safe to use as their MAYBE_NULL variants (e.g., PTR_TO_MAP_VALUE * is safe to be used as PTR_TO_MAP_VALUE_OR_NULL, provided both point * to the same map). * However, if the old MAYBE_NULL register then got NULL checked, * doing so could have affected others with the same id, and we can't * check for that because we lost the id when we converted to * a non-MAYBE_NULL variant. * So, as a general rule we don't allow mixing MAYBE_NULL and * non-MAYBE_NULL registers as well. */ if (rold->type != rcur->type) return false; switch (base_type(rold->type)) { case SCALAR_VALUE: if (env->explore_alu_limits) { /* explore_alu_limits disables tnum_in() and range_within() * logic and requires everything to be strict */ return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && check_scalar_ids(rold->id, rcur->id, idmap); } if (!rold->precise && exact == NOT_EXACT) return true; if ((rold->id & BPF_ADD_CONST) != (rcur->id & BPF_ADD_CONST)) return false; if ((rold->id & BPF_ADD_CONST) && (rold->off != rcur->off)) return false; /* Why check_ids() for scalar registers? * * Consider the following BPF code: * 1: r6 = ... unbound scalar, ID=a ... * 2: r7 = ... unbound scalar, ID=b ... * 3: if (r6 > r7) goto +1 * 4: r6 = r7 * 5: if (r6 > X) goto ... * 6: ... memory operation using r7 ... * * First verification path is [1-6]: * - at (4) same bpf_reg_state::id (b) would be assigned to r6 and r7; * - at (5) r6 would be marked <= X, sync_linked_regs() would also mark * r7 <= X, because r6 and r7 share same id. * Next verification path is [1-4, 6]. * * Instruction (6) would be reached in two states: * I. r6{.id=b}, r7{.id=b} via path 1-6; * II. r6{.id=a}, r7{.id=b} via path 1-4, 6. * * Use check_ids() to distinguish these states. * --- * Also verify that new value satisfies old value range knowledge. */ return range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off) && check_scalar_ids(rold->id, rcur->id, idmap); case PTR_TO_MAP_KEY: case PTR_TO_MAP_VALUE: case PTR_TO_MEM: case PTR_TO_BUF: case PTR_TO_TP_BUFFER: /* If the new min/max/var_off satisfy the old ones and * everything else matches, we are OK. */ return memcmp(rold, rcur, offsetof(struct bpf_reg_state, var_off)) == 0 && range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off) && check_ids(rold->id, rcur->id, idmap) && check_ids(rold->ref_obj_id, rcur->ref_obj_id, idmap); case PTR_TO_PACKET_META: case PTR_TO_PACKET: /* We must have at least as much range as the old ptr * did, so that any accesses which were safe before are * still safe. This is true even if old range < old off, * since someone could have accessed through (ptr - k), or * even done ptr -= k in a register, to get a safe access. */ if (rold->range > rcur->range) return false; /* If the offsets don't match, we can't trust our alignment; * nor can we be sure that we won't fall out of range. */ if (rold->off != rcur->off) return false; /* id relations must be preserved */ if (!check_ids(rold->id, rcur->id, idmap)) return false; /* new val must satisfy old val knowledge */ return range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off); case PTR_TO_STACK: /* two stack pointers are equal only if they're pointing to * the same stack frame, since fp-8 in foo != fp-8 in bar */ return regs_exact(rold, rcur, idmap) && rold->frameno == rcur->frameno; case PTR_TO_ARENA: return true; default: return regs_exact(rold, rcur, idmap); } } static struct bpf_reg_state unbound_reg; static __init int unbound_reg_init(void) { __mark_reg_unknown_imprecise(&unbound_reg); unbound_reg.live |= REG_LIVE_READ; return 0; } late_initcall(unbound_reg_init); static bool is_stack_all_misc(struct bpf_verifier_env *env, struct bpf_stack_state *stack) { u32 i; for (i = 0; i < ARRAY_SIZE(stack->slot_type); ++i) { if ((stack->slot_type[i] == STACK_MISC) || (stack->slot_type[i] == STACK_INVALID && env->allow_uninit_stack)) continue; return false; } return true; } static struct bpf_reg_state *scalar_reg_for_stack(struct bpf_verifier_env *env, struct bpf_stack_state *stack) { if (is_spilled_scalar_reg64(stack)) return &stack->spilled_ptr; if (is_stack_all_misc(env, stack)) return &unbound_reg; return NULL; } static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old, struct bpf_func_state *cur, struct bpf_idmap *idmap, enum exact_level exact) { int i, spi; /* walk slots of the explored stack and ignore any additional * slots in the current stack, since explored(safe) state * didn't use them */ for (i = 0; i < old->allocated_stack; i++) { struct bpf_reg_state *old_reg, *cur_reg; spi = i / BPF_REG_SIZE; if (exact != NOT_EXACT && (i >= cur->allocated_stack || old->stack[spi].slot_type[i % BPF_REG_SIZE] != cur->stack[spi].slot_type[i % BPF_REG_SIZE])) return false; if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ) && exact == NOT_EXACT) { i += BPF_REG_SIZE - 1; /* explored state didn't use this */ continue; } if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID) continue; if (env->allow_uninit_stack && old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC) continue; /* explored stack has more populated slots than current stack * and these slots were used */ if (i >= cur->allocated_stack) return false; /* 64-bit scalar spill vs all slots MISC and vice versa. * Load from all slots MISC produces unbound scalar. * Construct a fake register for such stack and call * regsafe() to ensure scalar ids are compared. */ old_reg = scalar_reg_for_stack(env, &old->stack[spi]); cur_reg = scalar_reg_for_stack(env, &cur->stack[spi]); if (old_reg && cur_reg) { if (!regsafe(env, old_reg, cur_reg, idmap, exact)) return false; i += BPF_REG_SIZE - 1; continue; } /* if old state was safe with misc data in the stack * it will be safe with zero-initialized stack. * The opposite is not true */ if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC && cur->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_ZERO) continue; if (old->stack[spi].slot_type[i % BPF_REG_SIZE] != cur->stack[spi].slot_type[i % BPF_REG_SIZE]) /* Ex: old explored (safe) state has STACK_SPILL in * this stack slot, but current has STACK_MISC -> * this verifier states are not equivalent, * return false to continue verification of this path */ return false; if (i % BPF_REG_SIZE != BPF_REG_SIZE - 1) continue; /* Both old and cur are having same slot_type */ switch (old->stack[spi].slot_type[BPF_REG_SIZE - 1]) { case STACK_SPILL: /* when explored and current stack slot are both storing * spilled registers, check that stored pointers types * are the same as well. * Ex: explored safe path could have stored * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8} * but current path has stored: * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16} * such verifier states are not equivalent. * return false to continue verification of this path */ if (!regsafe(env, &old->stack[spi].spilled_ptr, &cur->stack[spi].spilled_ptr, idmap, exact)) return false; break; case STACK_DYNPTR: old_reg = &old->stack[spi].spilled_ptr; cur_reg = &cur->stack[spi].spilled_ptr; if (old_reg->dynptr.type != cur_reg->dynptr.type || old_reg->dynptr.first_slot != cur_reg->dynptr.first_slot || !check_ids(old_reg->ref_obj_id, cur_reg->ref_obj_id, idmap)) return false; break; case STACK_ITER: old_reg = &old->stack[spi].spilled_ptr; cur_reg = &cur->stack[spi].spilled_ptr; /* iter.depth is not compared between states as it * doesn't matter for correctness and would otherwise * prevent convergence; we maintain it only to prevent * infinite loop check triggering, see * iter_active_depths_differ() */ if (old_reg->iter.btf != cur_reg->iter.btf || old_reg->iter.btf_id != cur_reg->iter.btf_id || old_reg->iter.state != cur_reg->iter.state || /* ignore {old_reg,cur_reg}->iter.depth, see above */ !check_ids(old_reg->ref_obj_id, cur_reg->ref_obj_id, idmap)) return false; break; case STACK_MISC: case STACK_ZERO: case STACK_INVALID: continue; /* Ensure that new unhandled slot types return false by default */ default: return false; } } return true; } static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur, struct bpf_idmap *idmap) { int i; if (old->acquired_refs != cur->acquired_refs) return false; for (i = 0; i < old->acquired_refs; i++) { if (!check_ids(old->refs[i].id, cur->refs[i].id, idmap) || old->refs[i].type != cur->refs[i].type) return false; switch (old->refs[i].type) { case REF_TYPE_PTR: break; case REF_TYPE_LOCK: if (old->refs[i].ptr != cur->refs[i].ptr) return false; break; default: WARN_ONCE(1, "Unhandled enum type for reference state: %d\n", old->refs[i].type); return false; } } return true; } /* compare two verifier states * * all states stored in state_list are known to be valid, since * verifier reached 'bpf_exit' instruction through them * * this function is called when verifier exploring different branches of * execution popped from the state stack. If it sees an old state that has * more strict register state and more strict stack state then this execution * branch doesn't need to be explored further, since verifier already * concluded that more strict state leads to valid finish. * * Therefore two states are equivalent if register state is more conservative * and explored stack state is more conservative than the current one. * Example: * explored current * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) * * In other words if current stack state (one being explored) has more * valid slots than old one that already passed validation, it means * the verifier can stop exploring and conclude that current state is valid too * * Similarly with registers. If explored state has register type as invalid * whereas register type in current state is meaningful, it means that * the current state will reach 'bpf_exit' instruction safely */ static bool func_states_equal(struct bpf_verifier_env *env, struct bpf_func_state *old, struct bpf_func_state *cur, enum exact_level exact) { int i; if (old->callback_depth > cur->callback_depth) return false; for (i = 0; i < MAX_BPF_REG; i++) if (!regsafe(env, &old->regs[i], &cur->regs[i], &env->idmap_scratch, exact)) return false; if (!stacksafe(env, old, cur, &env->idmap_scratch, exact)) return false; if (!refsafe(old, cur, &env->idmap_scratch)) return false; return true; } static void reset_idmap_scratch(struct bpf_verifier_env *env) { env->idmap_scratch.tmp_id_gen = env->id_gen; memset(&env->idmap_scratch.map, 0, sizeof(env->idmap_scratch.map)); } static bool states_equal(struct bpf_verifier_env *env, struct bpf_verifier_state *old, struct bpf_verifier_state *cur, enum exact_level exact) { int i; if (old->curframe != cur->curframe) return false; reset_idmap_scratch(env); /* Verification state from speculative execution simulation * must never prune a non-speculative execution one. */ if (old->speculative && !cur->speculative) return false; if (old->active_rcu_lock != cur->active_rcu_lock) return false; if (old->active_preempt_lock != cur->active_preempt_lock) return false; if (old->in_sleepable != cur->in_sleepable) return false; /* for states to be equal callsites have to be the same * and all frame states need to be equivalent */ for (i = 0; i <= old->curframe; i++) { if (old->frame[i]->callsite != cur->frame[i]->callsite) return false; if (!func_states_equal(env, old->frame[i], cur->frame[i], exact)) return false; } return true; } /* Return 0 if no propagation happened. Return negative error code if error * happened. Otherwise, return the propagated bit. */ static int propagate_liveness_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, struct bpf_reg_state *parent_reg) { u8 parent_flag = parent_reg->live & REG_LIVE_READ; u8 flag = reg->live & REG_LIVE_READ; int err; /* When comes here, read flags of PARENT_REG or REG could be any of * REG_LIVE_READ64, REG_LIVE_READ32, REG_LIVE_NONE. There is no need * of propagation if PARENT_REG has strongest REG_LIVE_READ64. */ if (parent_flag == REG_LIVE_READ64 || /* Or if there is no read flag from REG. */ !flag || /* Or if the read flag from REG is the same as PARENT_REG. */ parent_flag == flag) return 0; err = mark_reg_read(env, reg, parent_reg, flag); if (err) return err; return flag; } /* A write screens off any subsequent reads; but write marks come from the * straight-line code between a state and its parent. When we arrive at an * equivalent state (jump target or such) we didn't arrive by the straight-line * code, so read marks in the state must propagate to the parent regardless * of the state's write marks. That's what 'parent == state->parent' comparison * in mark_reg_read() is for. */ static int propagate_liveness(struct bpf_verifier_env *env, const struct bpf_verifier_state *vstate, struct bpf_verifier_state *vparent) { struct bpf_reg_state *state_reg, *parent_reg; struct bpf_func_state *state, *parent; int i, frame, err = 0; if (vparent->curframe != vstate->curframe) { WARN(1, "propagate_live: parent frame %d current frame %d\n", vparent->curframe, vstate->curframe); return -EFAULT; } /* Propagate read liveness of registers... */ BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG); for (frame = 0; frame <= vstate->curframe; frame++) { parent = vparent->frame[frame]; state = vstate->frame[frame]; parent_reg = parent->regs; state_reg = state->regs; /* We don't need to worry about FP liveness, it's read-only */ for (i = frame < vstate->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) { err = propagate_liveness_reg(env, &state_reg[i], &parent_reg[i]); if (err < 0) return err; if (err == REG_LIVE_READ64) mark_insn_zext(env, &parent_reg[i]); } /* Propagate stack slots. */ for (i = 0; i < state->allocated_stack / BPF_REG_SIZE && i < parent->allocated_stack / BPF_REG_SIZE; i++) { parent_reg = &parent->stack[i].spilled_ptr; state_reg = &state->stack[i].spilled_ptr; err = propagate_liveness_reg(env, state_reg, parent_reg); if (err < 0) return err; } } return 0; } /* find precise scalars in the previous equivalent state and * propagate them into the current state */ static int propagate_precision(struct bpf_verifier_env *env, const struct bpf_verifier_state *old) { struct bpf_reg_state *state_reg; struct bpf_func_state *state; int i, err = 0, fr; bool first; for (fr = old->curframe; fr >= 0; fr--) { state = old->frame[fr]; state_reg = state->regs; first = true; for (i = 0; i < BPF_REG_FP; i++, state_reg++) { if (state_reg->type != SCALAR_VALUE || !state_reg->precise || !(state_reg->live & REG_LIVE_READ)) continue; if (env->log.level & BPF_LOG_LEVEL2) { if (first) verbose(env, "frame %d: propagating r%d", fr, i); else verbose(env, ",r%d", i); } bt_set_frame_reg(&env->bt, fr, i); first = false; } for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { if (!is_spilled_reg(&state->stack[i])) continue; state_reg = &state->stack[i].spilled_ptr; if (state_reg->type != SCALAR_VALUE || !state_reg->precise || !(state_reg->live & REG_LIVE_READ)) continue; if (env->log.level & BPF_LOG_LEVEL2) { if (first) verbose(env, "frame %d: propagating fp%d", fr, (-i - 1) * BPF_REG_SIZE); else verbose(env, ",fp%d", (-i - 1) * BPF_REG_SIZE); } bt_set_frame_slot(&env->bt, fr, i); first = false; } if (!first) verbose(env, "\n"); } err = mark_chain_precision_batch(env); if (err < 0) return err; return 0; } static bool states_maybe_looping(struct bpf_verifier_state *old, struct bpf_verifier_state *cur) { struct bpf_func_state *fold, *fcur; int i, fr = cur->curframe; if (old->curframe != fr) return false; fold = old->frame[fr]; fcur = cur->frame[fr]; for (i = 0; i < MAX_BPF_REG; i++) if (memcmp(&fold->regs[i], &fcur->regs[i], offsetof(struct bpf_reg_state, parent))) return false; return true; } static bool is_iter_next_insn(struct bpf_verifier_env *env, int insn_idx) { return env->insn_aux_data[insn_idx].is_iter_next; } /* is_state_visited() handles iter_next() (see process_iter_next_call() for * terminology) calls specially: as opposed to bounded BPF loops, it *expects* * states to match, which otherwise would look like an infinite loop. So while * iter_next() calls are taken care of, we still need to be careful and * prevent erroneous and too eager declaration of "ininite loop", when * iterators are involved. * * Here's a situation in pseudo-BPF assembly form: * * 0: again: ; set up iter_next() call args * 1: r1 = &it ; <CHECKPOINT HERE> * 2: call bpf_iter_num_next ; this is iter_next() call * 3: if r0 == 0 goto done * 4: ... something useful here ... * 5: goto again ; another iteration * 6: done: * 7: r1 = &it * 8: call bpf_iter_num_destroy ; clean up iter state * 9: exit * * This is a typical loop. Let's assume that we have a prune point at 1:, * before we get to `call bpf_iter_num_next` (e.g., because of that `goto * again`, assuming other heuristics don't get in a way). * * When we first time come to 1:, let's say we have some state X. We proceed * to 2:, fork states, enqueue ACTIVE, validate NULL case successfully, exit. * Now we come back to validate that forked ACTIVE state. We proceed through * 3-5, come to goto, jump to 1:. Let's assume our state didn't change, so we * are converging. But the problem is that we don't know that yet, as this * convergence has to happen at iter_next() call site only. So if nothing is * done, at 1: verifier will use bounded loop logic and declare infinite * looping (and would be *technically* correct, if not for iterator's * "eventual sticky NULL" contract, see process_iter_next_call()). But we * don't want that. So what we do in process_iter_next_call() when we go on * another ACTIVE iteration, we bump slot->iter.depth, to mark that it's * a different iteration. So when we suspect an infinite loop, we additionally * check if any of the *ACTIVE* iterator states depths differ. If yes, we * pretend we are not looping and wait for next iter_next() call. * * This only applies to ACTIVE state. In DRAINED state we don't expect to * loop, because that would actually mean infinite loop, as DRAINED state is * "sticky", and so we'll keep returning into the same instruction with the * same state (at least in one of possible code paths). * * This approach allows to keep infinite loop heuristic even in the face of * active iterator. E.g., C snippet below is and will be detected as * inifintely looping: * * struct bpf_iter_num it; * int *p, x; * * bpf_iter_num_new(&it, 0, 10); * while ((p = bpf_iter_num_next(&t))) { * x = p; * while (x--) {} // <<-- infinite loop here * } * */ static bool iter_active_depths_differ(struct bpf_verifier_state *old, struct bpf_verifier_state *cur) { struct bpf_reg_state *slot, *cur_slot; struct bpf_func_state *state; int i, fr; for (fr = old->curframe; fr >= 0; fr--) { state = old->frame[fr]; for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { if (state->stack[i].slot_type[0] != STACK_ITER) continue; slot = &state->stack[i].spilled_ptr; if (slot->iter.state != BPF_ITER_STATE_ACTIVE) continue; cur_slot = &cur->frame[fr]->stack[i].spilled_ptr; if (cur_slot->iter.depth != slot->iter.depth) return true; } } return false; } static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) { struct bpf_verifier_state_list *new_sl; struct bpf_verifier_state_list *sl, **pprev; struct bpf_verifier_state *cur = env->cur_state, *new, *loop_entry; int i, j, n, err, states_cnt = 0; bool force_new_state, add_new_state, force_exact; force_new_state = env->test_state_freq || is_force_checkpoint(env, insn_idx) || /* Avoid accumulating infinitely long jmp history */ cur->insn_hist_end - cur->insn_hist_start > 40; /* bpf progs typically have pruning point every 4 instructions * http://vger.kernel.org/bpfconf2019.html#session-1 * Do not add new state for future pruning if the verifier hasn't seen * at least 2 jumps and at least 8 instructions. * This heuristics helps decrease 'total_states' and 'peak_states' metric. * In tests that amounts to up to 50% reduction into total verifier * memory consumption and 20% verifier time speedup. */ add_new_state = force_new_state; if (env->jmps_processed - env->prev_jmps_processed >= 2 && env->insn_processed - env->prev_insn_processed >= 8) add_new_state = true; pprev = explored_state(env, insn_idx); sl = *pprev; clean_live_states(env, insn_idx, cur); while (sl) { states_cnt++; if (sl->state.insn_idx != insn_idx) goto next; if (sl->state.branches) { struct bpf_func_state *frame = sl->state.frame[sl->state.curframe]; if (frame->in_async_callback_fn && frame->async_entry_cnt != cur->frame[cur->curframe]->async_entry_cnt) { /* Different async_entry_cnt means that the verifier is * processing another entry into async callback. * Seeing the same state is not an indication of infinite * loop or infinite recursion. * But finding the same state doesn't mean that it's safe * to stop processing the current state. The previous state * hasn't yet reached bpf_exit, since state.branches > 0. * Checking in_async_callback_fn alone is not enough either. * Since the verifier still needs to catch infinite loops * inside async callbacks. */ goto skip_inf_loop_check; } /* BPF open-coded iterators loop detection is special. * states_maybe_looping() logic is too simplistic in detecting * states that *might* be equivalent, because it doesn't know * about ID remapping, so don't even perform it. * See process_iter_next_call() and iter_active_depths_differ() * for overview of the logic. When current and one of parent * states are detected as equivalent, it's a good thing: we prove * convergence and can stop simulating further iterations. * It's safe to assume that iterator loop will finish, taking into * account iter_next() contract of eventually returning * sticky NULL result. * * Note, that states have to be compared exactly in this case because * read and precision marks might not be finalized inside the loop. * E.g. as in the program below: * * 1. r7 = -16 * 2. r6 = bpf_get_prandom_u32() * 3. while (bpf_iter_num_next(&fp[-8])) { * 4. if (r6 != 42) { * 5. r7 = -32 * 6. r6 = bpf_get_prandom_u32() * 7. continue * 8. } * 9. r0 = r10 * 10. r0 += r7 * 11. r8 = *(u64 *)(r0 + 0) * 12. r6 = bpf_get_prandom_u32() * 13. } * * Here verifier would first visit path 1-3, create a checkpoint at 3 * with r7=-16, continue to 4-7,3. Existing checkpoint at 3 does * not have read or precision mark for r7 yet, thus inexact states * comparison would discard current state with r7=-32 * => unsafe memory access at 11 would not be caught. */ if (is_iter_next_insn(env, insn_idx)) { if (states_equal(env, &sl->state, cur, RANGE_WITHIN)) { struct bpf_func_state *cur_frame; struct bpf_reg_state *iter_state, *iter_reg; int spi; cur_frame = cur->frame[cur->curframe]; /* btf_check_iter_kfuncs() enforces that * iter state pointer is always the first arg */ iter_reg = &cur_frame->regs[BPF_REG_1]; /* current state is valid due to states_equal(), * so we can assume valid iter and reg state, * no need for extra (re-)validations */ spi = __get_spi(iter_reg->off + iter_reg->var_off.value); iter_state = &func(env, iter_reg)->stack[spi].spilled_ptr; if (iter_state->iter.state == BPF_ITER_STATE_ACTIVE) { update_loop_entry(cur, &sl->state); goto hit; } } goto skip_inf_loop_check; } if (is_may_goto_insn_at(env, insn_idx)) { if (sl->state.may_goto_depth != cur->may_goto_depth && states_equal(env, &sl->state, cur, RANGE_WITHIN)) { update_loop_entry(cur, &sl->state); goto hit; } } if (calls_callback(env, insn_idx)) { if (states_equal(env, &sl->state, cur, RANGE_WITHIN)) goto hit; goto skip_inf_loop_check; } /* attempt to detect infinite loop to avoid unnecessary doomed work */ if (states_maybe_looping(&sl->state, cur) && states_equal(env, &sl->state, cur, EXACT) && !iter_active_depths_differ(&sl->state, cur) && sl->state.may_goto_depth == cur->may_goto_depth && sl->state.callback_unroll_depth == cur->callback_unroll_depth) { verbose_linfo(env, insn_idx, "; "); verbose(env, "infinite loop detected at insn %d\n", insn_idx); verbose(env, "cur state:"); print_verifier_state(env, cur->frame[cur->curframe], true); verbose(env, "old state:"); print_verifier_state(env, sl->state.frame[cur->curframe], true); return -EINVAL; } /* if the verifier is processing a loop, avoid adding new state * too often, since different loop iterations have distinct * states and may not help future pruning. * This threshold shouldn't be too low to make sure that * a loop with large bound will be rejected quickly. * The most abusive loop will be: * r1 += 1 * if r1 < 1000000 goto pc-2 * 1M insn_procssed limit / 100 == 10k peak states. * This threshold shouldn't be too high either, since states * at the end of the loop are likely to be useful in pruning. */ skip_inf_loop_check: if (!force_new_state && env->jmps_processed - env->prev_jmps_processed < 20 && env->insn_processed - env->prev_insn_processed < 100) add_new_state = false; goto miss; } /* If sl->state is a part of a loop and this loop's entry is a part of * current verification path then states have to be compared exactly. * 'force_exact' is needed to catch the following case: * * initial Here state 'succ' was processed first, * | it was eventually tracked to produce a * V state identical to 'hdr'. * .---------> hdr All branches from 'succ' had been explored * | | and thus 'succ' has its .branches == 0. * | V * | .------... Suppose states 'cur' and 'succ' correspond * | | | to the same instruction + callsites. * | V V In such case it is necessary to check * | ... ... if 'succ' and 'cur' are states_equal(). * | | | If 'succ' and 'cur' are a part of the * | V V same loop exact flag has to be set. * | succ <- cur To check if that is the case, verify * | | if loop entry of 'succ' is in current * | V DFS path. * | ... * | | * '----' * * Additional details are in the comment before get_loop_entry(). */ loop_entry = get_loop_entry(&sl->state); force_exact = loop_entry && loop_entry->branches > 0; if (states_equal(env, &sl->state, cur, force_exact ? RANGE_WITHIN : NOT_EXACT)) { if (force_exact) update_loop_entry(cur, loop_entry); hit: sl->hit_cnt++; /* reached equivalent register/stack state, * prune the search. * Registers read by the continuation are read by us. * If we have any write marks in env->cur_state, they * will prevent corresponding reads in the continuation * from reaching our parent (an explored_state). Our * own state will get the read marks recorded, but * they'll be immediately forgotten as we're pruning * this state and will pop a new one. */ err = propagate_liveness(env, &sl->state, cur); /* if previous state reached the exit with precision and * current state is equivalent to it (except precision marks) * the precision needs to be propagated back in * the current state. */ if (is_jmp_point(env, env->insn_idx)) err = err ? : push_insn_history(env, cur, 0, 0); err = err ? : propagate_precision(env, &sl->state); if (err) return err; return 1; } miss: /* when new state is not going to be added do not increase miss count. * Otherwise several loop iterations will remove the state * recorded earlier. The goal of these heuristics is to have * states from some iterations of the loop (some in the beginning * and some at the end) to help pruning. */ if (add_new_state) sl->miss_cnt++; /* heuristic to determine whether this state is beneficial * to keep checking from state equivalence point of view. * Higher numbers increase max_states_per_insn and verification time, * but do not meaningfully decrease insn_processed. * 'n' controls how many times state could miss before eviction. * Use bigger 'n' for checkpoints because evicting checkpoint states * too early would hinder iterator convergence. */ n = is_force_checkpoint(env, insn_idx) && sl->state.branches > 0 ? 64 : 3; if (sl->miss_cnt > sl->hit_cnt * n + n) { /* the state is unlikely to be useful. Remove it to * speed up verification */ *pprev = sl->next; if (sl->state.frame[0]->regs[0].live & REG_LIVE_DONE && !sl->state.used_as_loop_entry) { u32 br = sl->state.branches; WARN_ONCE(br, "BUG live_done but branches_to_explore %d\n", br); free_verifier_state(&sl->state, false); kfree(sl); env->peak_states--; } else { /* cannot free this state, since parentage chain may * walk it later. Add it for free_list instead to * be freed at the end of verification */ sl->next = env->free_list; env->free_list = sl; } sl = *pprev; continue; } next: pprev = &sl->next; sl = *pprev; } if (env->max_states_per_insn < states_cnt) env->max_states_per_insn = states_cnt; if (!env->bpf_capable && states_cnt > BPF_COMPLEXITY_LIMIT_STATES) return 0; if (!add_new_state) return 0; /* There were no equivalent states, remember the current one. * Technically the current state is not proven to be safe yet, * but it will either reach outer most bpf_exit (which means it's safe) * or it will be rejected. When there are no loops the verifier won't be * seeing this tuple (frame[0].callsite, frame[1].callsite, .. insn_idx) * again on the way to bpf_exit. * When looping the sl->state.branches will be > 0 and this state * will not be considered for equivalence until branches == 0. */ new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL); if (!new_sl) return -ENOMEM; env->total_states++; env->peak_states++; env->prev_jmps_processed = env->jmps_processed; env->prev_insn_processed = env->insn_processed; /* forget precise markings we inherited, see __mark_chain_precision */ if (env->bpf_capable) mark_all_scalars_imprecise(env, cur); /* add new state to the head of linked list */ new = &new_sl->state; err = copy_verifier_state(new, cur); if (err) { free_verifier_state(new, false); kfree(new_sl); return err; } new->insn_idx = insn_idx; WARN_ONCE(new->branches != 1, "BUG is_state_visited:branches_to_explore=%d insn %d\n", new->branches, insn_idx); cur->parent = new; cur->first_insn_idx = insn_idx; cur->insn_hist_start = cur->insn_hist_end; cur->dfs_depth = new->dfs_depth + 1; new_sl->next = *explored_state(env, insn_idx); *explored_state(env, insn_idx) = new_sl; /* connect new state to parentage chain. Current frame needs all * registers connected. Only r6 - r9 of the callers are alive (pushed * to the stack implicitly by JITs) so in callers' frames connect just * r6 - r9 as an optimization. Callers will have r1 - r5 connected to * the state of the call instruction (with WRITTEN set), and r0 comes * from callee with its full parentage chain, anyway. */ /* clear write marks in current state: the writes we did are not writes * our child did, so they don't screen off its reads from us. * (There are no read marks in current state, because reads always mark * their parent and current state never has children yet. Only * explored_states can get read marks.) */ for (j = 0; j <= cur->curframe; j++) { for (i = j < cur->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) cur->frame[j]->regs[i].parent = &new->frame[j]->regs[i]; for (i = 0; i < BPF_REG_FP; i++) cur->frame[j]->regs[i].live = REG_LIVE_NONE; } /* all stack frames are accessible from callee, clear them all */ for (j = 0; j <= cur->curframe; j++) { struct bpf_func_state *frame = cur->frame[j]; struct bpf_func_state *newframe = new->frame[j]; for (i = 0; i < frame->allocated_stack / BPF_REG_SIZE; i++) { frame->stack[i].spilled_ptr.live = REG_LIVE_NONE; frame->stack[i].spilled_ptr.parent = &newframe->stack[i].spilled_ptr; } } return 0; } /* Return true if it's OK to have the same insn return a different type. */ static bool reg_type_mismatch_ok(enum bpf_reg_type type) { switch (base_type(type)) { case PTR_TO_CTX: case PTR_TO_SOCKET: case PTR_TO_SOCK_COMMON: case PTR_TO_TCP_SOCK: case PTR_TO_XDP_SOCK: case PTR_TO_BTF_ID: case PTR_TO_ARENA: return false; default: return true; } } /* If an instruction was previously used with particular pointer types, then we * need to be careful to avoid cases such as the below, where it may be ok * for one branch accessing the pointer, but not ok for the other branch: * * R1 = sock_ptr * goto X; * ... * R1 = some_other_valid_ptr; * goto X; * ... * R2 = *(u32 *)(R1 + 0); */ static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev) { return src != prev && (!reg_type_mismatch_ok(src) || !reg_type_mismatch_ok(prev)); } static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type type, bool allow_trust_mismatch) { enum bpf_reg_type *prev_type = &env->insn_aux_data[env->insn_idx].ptr_type; if (*prev_type == NOT_INIT) { /* Saw a valid insn * dst_reg = *(u32 *)(src_reg + off) * save type to validate intersecting paths */ *prev_type = type; } else if (reg_type_mismatch(type, *prev_type)) { /* Abuser program is trying to use the same insn * dst_reg = *(u32*) (src_reg + off) * with different pointer types: * src_reg == ctx in one branch and * src_reg == stack|map in some other branch. * Reject it. */ if (allow_trust_mismatch && base_type(type) == PTR_TO_BTF_ID && base_type(*prev_type) == PTR_TO_BTF_ID) { /* * Have to support a use case when one path through * the program yields TRUSTED pointer while another * is UNTRUSTED. Fallback to UNTRUSTED to generate * BPF_PROBE_MEM/BPF_PROBE_MEMSX. */ *prev_type = PTR_TO_BTF_ID | PTR_UNTRUSTED; } else { verbose(env, "same insn cannot be used with different pointers\n"); return -EINVAL; } } return 0; } static int do_check(struct bpf_verifier_env *env) { bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); struct bpf_verifier_state *state = env->cur_state; struct bpf_insn *insns = env->prog->insnsi; struct bpf_reg_state *regs; int insn_cnt = env->prog->len; bool do_print_state = false; int prev_insn_idx = -1; for (;;) { bool exception_exit = false; struct bpf_insn *insn; u8 class; int err; /* reset current history entry on each new instruction */ env->cur_hist_ent = NULL; env->prev_insn_idx = prev_insn_idx; if (env->insn_idx >= insn_cnt) { verbose(env, "invalid insn idx %d insn_cnt %d\n", env->insn_idx, insn_cnt); return -EFAULT; } insn = &insns[env->insn_idx]; class = BPF_CLASS(insn->code); if (++env->insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { verbose(env, "BPF program is too large. Processed %d insn\n", env->insn_processed); return -E2BIG; } state->last_insn_idx = env->prev_insn_idx; if (is_prune_point(env, env->insn_idx)) { err = is_state_visited(env, env->insn_idx); if (err < 0) return err; if (err == 1) { /* found equivalent state, can prune the search */ if (env->log.level & BPF_LOG_LEVEL) { if (do_print_state) verbose(env, "\nfrom %d to %d%s: safe\n", env->prev_insn_idx, env->insn_idx, env->cur_state->speculative ? " (speculative execution)" : ""); else verbose(env, "%d: safe\n", env->insn_idx); } goto process_bpf_exit; } } if (is_jmp_point(env, env->insn_idx)) { err = push_insn_history(env, state, 0, 0); if (err) return err; } if (signal_pending(current)) return -EAGAIN; if (need_resched()) cond_resched(); if (env->log.level & BPF_LOG_LEVEL2 && do_print_state) { verbose(env, "\nfrom %d to %d%s:", env->prev_insn_idx, env->insn_idx, env->cur_state->speculative ? " (speculative execution)" : ""); print_verifier_state(env, state->frame[state->curframe], true); do_print_state = false; } if (env->log.level & BPF_LOG_LEVEL) { const struct bpf_insn_cbs cbs = { .cb_call = disasm_kfunc_name, .cb_print = verbose, .private_data = env, }; if (verifier_state_scratched(env)) print_insn_state(env, state->frame[state->curframe]); verbose_linfo(env, env->insn_idx, "; "); env->prev_log_pos = env->log.end_pos; verbose(env, "%d: ", env->insn_idx); print_bpf_insn(&cbs, insn, env->allow_ptr_leaks); env->prev_insn_print_pos = env->log.end_pos - env->prev_log_pos; env->prev_log_pos = env->log.end_pos; } if (bpf_prog_is_offloaded(env->prog->aux)) { err = bpf_prog_offload_verify_insn(env, env->insn_idx, env->prev_insn_idx); if (err) return err; } regs = cur_regs(env); sanitize_mark_insn_seen(env); prev_insn_idx = env->insn_idx; if (class == BPF_ALU || class == BPF_ALU64) { err = check_alu_op(env, insn); if (err) return err; } else if (class == BPF_LDX) { enum bpf_reg_type src_reg_type; /* check for reserved fields is already done */ /* check src operand */ err = check_reg_arg(env, insn->src_reg, SRC_OP); if (err) return err; err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); if (err) return err; src_reg_type = regs[insn->src_reg].type; /* check that memory (src_reg + off) is readable, * the state of dst_reg will be updated by this func */ err = check_mem_access(env, env->insn_idx, insn->src_reg, insn->off, BPF_SIZE(insn->code), BPF_READ, insn->dst_reg, false, BPF_MODE(insn->code) == BPF_MEMSX); err = err ?: save_aux_ptr_type(env, src_reg_type, true); err = err ?: reg_bounds_sanity_check(env, ®s[insn->dst_reg], "ldx"); if (err) return err; } else if (class == BPF_STX) { enum bpf_reg_type dst_reg_type; if (BPF_MODE(insn->code) == BPF_ATOMIC) { err = check_atomic(env, env->insn_idx, insn); if (err) return err; env->insn_idx++; continue; } if (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0) { verbose(env, "BPF_STX uses reserved fields\n"); return -EINVAL; } /* check src1 operand */ err = check_reg_arg(env, insn->src_reg, SRC_OP); if (err) return err; /* check src2 operand */ err = check_reg_arg(env, insn->dst_reg, SRC_OP); if (err) return err; dst_reg_type = regs[insn->dst_reg].type; /* check that memory (dst_reg + off) is writeable */ err = check_mem_access(env, env->insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_WRITE, insn->src_reg, false, false); if (err) return err; err = save_aux_ptr_type(env, dst_reg_type, false); if (err) return err; } else if (class == BPF_ST) { enum bpf_reg_type dst_reg_type; if (BPF_MODE(insn->code) != BPF_MEM || insn->src_reg != BPF_REG_0) { verbose(env, "BPF_ST uses reserved fields\n"); return -EINVAL; } /* check src operand */ err = check_reg_arg(env, insn->dst_reg, SRC_OP); if (err) return err; dst_reg_type = regs[insn->dst_reg].type; /* check that memory (dst_reg + off) is writeable */ err = check_mem_access(env, env->insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_WRITE, -1, false, false); if (err) return err; err = save_aux_ptr_type(env, dst_reg_type, false); if (err) return err; } else if (class == BPF_JMP || class == BPF_JMP32) { u8 opcode = BPF_OP(insn->code); env->jmps_processed++; if (opcode == BPF_CALL) { if (BPF_SRC(insn->code) != BPF_K || (insn->src_reg != BPF_PSEUDO_KFUNC_CALL && insn->off != 0) || (insn->src_reg != BPF_REG_0 && insn->src_reg != BPF_PSEUDO_CALL && insn->src_reg != BPF_PSEUDO_KFUNC_CALL) || insn->dst_reg != BPF_REG_0 || class == BPF_JMP32) { verbose(env, "BPF_CALL uses reserved fields\n"); return -EINVAL; } if (cur_func(env)->active_locks) { if ((insn->src_reg == BPF_REG_0 && insn->imm != BPF_FUNC_spin_unlock) || (insn->src_reg == BPF_PSEUDO_KFUNC_CALL && (insn->off != 0 || !is_bpf_graph_api_kfunc(insn->imm)))) { verbose(env, "function calls are not allowed while holding a lock\n"); return -EINVAL; } } if (insn->src_reg == BPF_PSEUDO_CALL) { err = check_func_call(env, insn, &env->insn_idx); } else if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { err = check_kfunc_call(env, insn, &env->insn_idx); if (!err && is_bpf_throw_kfunc(insn)) { exception_exit = true; goto process_bpf_exit_full; } } else { err = check_helper_call(env, insn, &env->insn_idx); } if (err) return err; mark_reg_scratched(env, BPF_REG_0); } else if (opcode == BPF_JA) { if (BPF_SRC(insn->code) != BPF_K || insn->src_reg != BPF_REG_0 || insn->dst_reg != BPF_REG_0 || (class == BPF_JMP && insn->imm != 0) || (class == BPF_JMP32 && insn->off != 0)) { verbose(env, "BPF_JA uses reserved fields\n"); return -EINVAL; } if (class == BPF_JMP) env->insn_idx += insn->off + 1; else env->insn_idx += insn->imm + 1; continue; } else if (opcode == BPF_EXIT) { if (BPF_SRC(insn->code) != BPF_K || insn->imm != 0 || insn->src_reg != BPF_REG_0 || insn->dst_reg != BPF_REG_0 || class == BPF_JMP32) { verbose(env, "BPF_EXIT uses reserved fields\n"); return -EINVAL; } process_bpf_exit_full: /* We must do check_reference_leak here before * prepare_func_exit to handle the case when * state->curframe > 0, it may be a callback * function, for which reference_state must * match caller reference state when it exits. */ err = check_resource_leak(env, exception_exit, !env->cur_state->curframe, "BPF_EXIT instruction"); if (err) return err; /* The side effect of the prepare_func_exit * which is being skipped is that it frees * bpf_func_state. Typically, process_bpf_exit * will only be hit with outermost exit. * copy_verifier_state in pop_stack will handle * freeing of any extra bpf_func_state left over * from not processing all nested function * exits. We also skip return code checks as * they are not needed for exceptional exits. */ if (exception_exit) goto process_bpf_exit; if (state->curframe) { /* exit from nested function */ err = prepare_func_exit(env, &env->insn_idx); if (err) return err; do_print_state = true; continue; } err = check_return_code(env, BPF_REG_0, "R0"); if (err) return err; process_bpf_exit: mark_verifier_state_scratched(env); update_branch_counts(env, env->cur_state); err = pop_stack(env, &prev_insn_idx, &env->insn_idx, pop_log); if (err < 0) { if (err != -ENOENT) return err; break; } else { do_print_state = true; continue; } } else { err = check_cond_jmp_op(env, insn, &env->insn_idx); if (err) return err; } } else if (class == BPF_LD) { u8 mode = BPF_MODE(insn->code); if (mode == BPF_ABS || mode == BPF_IND) { err = check_ld_abs(env, insn); if (err) return err; } else if (mode == BPF_IMM) { err = check_ld_imm(env, insn); if (err) return err; env->insn_idx++; sanitize_mark_insn_seen(env); } else { verbose(env, "invalid BPF_LD mode\n"); return -EINVAL; } } else { verbose(env, "unknown insn class %d\n", class); return -EINVAL; } env->insn_idx++; } return 0; } static int find_btf_percpu_datasec(struct btf *btf) { const struct btf_type *t; const char *tname; int i, n; /* * Both vmlinux and module each have their own ".data..percpu" * DATASECs in BTF. So for module's case, we need to skip vmlinux BTF * types to look at only module's own BTF types. */ n = btf_nr_types(btf); if (btf_is_module(btf)) i = btf_nr_types(btf_vmlinux); else i = 1; for(; i < n; i++) { t = btf_type_by_id(btf, i); if (BTF_INFO_KIND(t->info) != BTF_KIND_DATASEC) continue; tname = btf_name_by_offset(btf, t->name_off); if (!strcmp(tname, ".data..percpu")) return i; } return -ENOENT; } /* replace pseudo btf_id with kernel symbol address */ static int check_pseudo_btf_id(struct bpf_verifier_env *env, struct bpf_insn *insn, struct bpf_insn_aux_data *aux) { const struct btf_var_secinfo *vsi; const struct btf_type *datasec; struct btf_mod_pair *btf_mod; const struct btf_type *t; const char *sym_name; bool percpu = false; u32 type, id = insn->imm; struct btf *btf; s32 datasec_id; u64 addr; int i, btf_fd, err; btf_fd = insn[1].imm; if (btf_fd) { btf = btf_get_by_fd(btf_fd); if (IS_ERR(btf)) { verbose(env, "invalid module BTF object FD specified.\n"); return -EINVAL; } } else { if (!btf_vmlinux) { verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n"); return -EINVAL; } btf = btf_vmlinux; btf_get(btf); } t = btf_type_by_id(btf, id); if (!t) { verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id); err = -ENOENT; goto err_put; } if (!btf_type_is_var(t) && !btf_type_is_func(t)) { verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR or KIND_FUNC\n", id); err = -EINVAL; goto err_put; } sym_name = btf_name_by_offset(btf, t->name_off); addr = kallsyms_lookup_name(sym_name); if (!addr) { verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n", sym_name); err = -ENOENT; goto err_put; } insn[0].imm = (u32)addr; insn[1].imm = addr >> 32; if (btf_type_is_func(t)) { aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY; aux->btf_var.mem_size = 0; goto check_btf; } datasec_id = find_btf_percpu_datasec(btf); if (datasec_id > 0) { datasec = btf_type_by_id(btf, datasec_id); for_each_vsi(i, datasec, vsi) { if (vsi->type == id) { percpu = true; break; } } } type = t->type; t = btf_type_skip_modifiers(btf, type, NULL); if (percpu) { aux->btf_var.reg_type = PTR_TO_BTF_ID | MEM_PERCPU; aux->btf_var.btf = btf; aux->btf_var.btf_id = type; } else if (!btf_type_is_struct(t)) { const struct btf_type *ret; const char *tname; u32 tsize; /* resolve the type size of ksym. */ ret = btf_resolve_size(btf, t, &tsize); if (IS_ERR(ret)) { tname = btf_name_by_offset(btf, t->name_off); verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n", tname, PTR_ERR(ret)); err = -EINVAL; goto err_put; } aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY; aux->btf_var.mem_size = tsize; } else { aux->btf_var.reg_type = PTR_TO_BTF_ID; aux->btf_var.btf = btf; aux->btf_var.btf_id = type; } check_btf: /* check whether we recorded this BTF (and maybe module) already */ for (i = 0; i < env->used_btf_cnt; i++) { if (env->used_btfs[i].btf == btf) { btf_put(btf); return 0; } } if (env->used_btf_cnt >= MAX_USED_BTFS) { err = -E2BIG; goto err_put; } btf_mod = &env->used_btfs[env->used_btf_cnt]; btf_mod->btf = btf; btf_mod->module = NULL; /* if we reference variables from kernel module, bump its refcount */ if (btf_is_module(btf)) { btf_mod->module = btf_try_get_module(btf); if (!btf_mod->module) { err = -ENXIO; goto err_put; } } env->used_btf_cnt++; return 0; err_put: btf_put(btf); return err; } static bool is_tracing_prog_type(enum bpf_prog_type type) { switch (type) { case BPF_PROG_TYPE_KPROBE: case BPF_PROG_TYPE_TRACEPOINT: case BPF_PROG_TYPE_PERF_EVENT: case BPF_PROG_TYPE_RAW_TRACEPOINT: case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE: return true; default: return false; } } static int check_map_prog_compatibility(struct bpf_verifier_env *env, struct bpf_map *map, struct bpf_prog *prog) { enum bpf_prog_type prog_type = resolve_prog_type(prog); if (btf_record_has_field(map->record, BPF_LIST_HEAD) || btf_record_has_field(map->record, BPF_RB_ROOT)) { if (is_tracing_prog_type(prog_type)) { verbose(env, "tracing progs cannot use bpf_{list_head,rb_root} yet\n"); return -EINVAL; } } if (btf_record_has_field(map->record, BPF_SPIN_LOCK)) { if (prog_type == BPF_PROG_TYPE_SOCKET_FILTER) { verbose(env, "socket filter progs cannot use bpf_spin_lock yet\n"); return -EINVAL; } if (is_tracing_prog_type(prog_type)) { verbose(env, "tracing progs cannot use bpf_spin_lock yet\n"); return -EINVAL; } } if (btf_record_has_field(map->record, BPF_TIMER)) { if (is_tracing_prog_type(prog_type)) { verbose(env, "tracing progs cannot use bpf_timer yet\n"); return -EINVAL; } } if (btf_record_has_field(map->record, BPF_WORKQUEUE)) { if (is_tracing_prog_type(prog_type)) { verbose(env, "tracing progs cannot use bpf_wq yet\n"); return -EINVAL; } } if ((bpf_prog_is_offloaded(prog->aux) || bpf_map_is_offloaded(map)) && !bpf_offload_prog_map_match(prog, map)) { verbose(env, "offload device mismatch between prog and map\n"); return -EINVAL; } if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) { verbose(env, "bpf_struct_ops map cannot be used in prog\n"); return -EINVAL; } if (prog->sleepable) switch (map->map_type) { case BPF_MAP_TYPE_HASH: case BPF_MAP_TYPE_LRU_HASH: case BPF_MAP_TYPE_ARRAY: case BPF_MAP_TYPE_PERCPU_HASH: case BPF_MAP_TYPE_PERCPU_ARRAY: case BPF_MAP_TYPE_LRU_PERCPU_HASH: case BPF_MAP_TYPE_ARRAY_OF_MAPS: case BPF_MAP_TYPE_HASH_OF_MAPS: case BPF_MAP_TYPE_RINGBUF: case BPF_MAP_TYPE_USER_RINGBUF: case BPF_MAP_TYPE_INODE_STORAGE: case BPF_MAP_TYPE_SK_STORAGE: case BPF_MAP_TYPE_TASK_STORAGE: case BPF_MAP_TYPE_CGRP_STORAGE: case BPF_MAP_TYPE_QUEUE: case BPF_MAP_TYPE_STACK: case BPF_MAP_TYPE_ARENA: break; default: verbose(env, "Sleepable programs can only use array, hash, ringbuf and local storage maps\n"); return -EINVAL; } return 0; } static bool bpf_map_is_cgroup_storage(struct bpf_map *map) { return (map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE || map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE); } /* Add map behind fd to used maps list, if it's not already there, and return * its index. Also set *reused to true if this map was already in the list of * used maps. * Returns <0 on error, or >= 0 index, on success. */ static int add_used_map_from_fd(struct bpf_verifier_env *env, int fd, bool *reused) { CLASS(fd, f)(fd); struct bpf_map *map; int i; map = __bpf_map_get(f); if (IS_ERR(map)) { verbose(env, "fd %d is not pointing to valid bpf_map\n", fd); return PTR_ERR(map); } /* check whether we recorded this map already */ for (i = 0; i < env->used_map_cnt; i++) { if (env->used_maps[i] == map) { *reused = true; return i; } } if (env->used_map_cnt >= MAX_USED_MAPS) { verbose(env, "The total number of maps per program has reached the limit of %u\n", MAX_USED_MAPS); return -E2BIG; } if (env->prog->sleepable) atomic64_inc(&map->sleepable_refcnt); /* hold the map. If the program is rejected by verifier, * the map will be released by release_maps() or it * will be used by the valid program until it's unloaded * and all maps are released in bpf_free_used_maps() */ bpf_map_inc(map); *reused = false; env->used_maps[env->used_map_cnt++] = map; return env->used_map_cnt - 1; } /* find and rewrite pseudo imm in ld_imm64 instructions: * * 1. if it accesses map FD, replace it with actual map pointer. * 2. if it accesses btf_id of a VAR, replace it with pointer to the var. * * NOTE: btf_vmlinux is required for converting pseudo btf_id. */ static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env) { struct bpf_insn *insn = env->prog->insnsi; int insn_cnt = env->prog->len; int i, err; err = bpf_prog_calc_tag(env->prog); if (err) return err; for (i = 0; i < insn_cnt; i++, insn++) { if (BPF_CLASS(insn->code) == BPF_LDX && ((BPF_MODE(insn->code) != BPF_MEM && BPF_MODE(insn->code) != BPF_MEMSX) || insn->imm != 0)) { verbose(env, "BPF_LDX uses reserved fields\n"); return -EINVAL; } if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { struct bpf_insn_aux_data *aux; struct bpf_map *map; int map_idx; u64 addr; u32 fd; bool reused; if (i == insn_cnt - 1 || insn[1].code != 0 || insn[1].dst_reg != 0 || insn[1].src_reg != 0 || insn[1].off != 0) { verbose(env, "invalid bpf_ld_imm64 insn\n"); return -EINVAL; } if (insn[0].src_reg == 0) /* valid generic load 64-bit imm */ goto next_insn; if (insn[0].src_reg == BPF_PSEUDO_BTF_ID) { aux = &env->insn_aux_data[i]; err = check_pseudo_btf_id(env, insn, aux); if (err) return err; goto next_insn; } if (insn[0].src_reg == BPF_PSEUDO_FUNC) { aux = &env->insn_aux_data[i]; aux->ptr_type = PTR_TO_FUNC; goto next_insn; } /* In final convert_pseudo_ld_imm64() step, this is * converted into regular 64-bit imm load insn. */ switch (insn[0].src_reg) { case BPF_PSEUDO_MAP_VALUE: case BPF_PSEUDO_MAP_IDX_VALUE: break; case BPF_PSEUDO_MAP_FD: case BPF_PSEUDO_MAP_IDX: if (insn[1].imm == 0) break; fallthrough; default: verbose(env, "unrecognized bpf_ld_imm64 insn\n"); return -EINVAL; } switch (insn[0].src_reg) { case BPF_PSEUDO_MAP_IDX_VALUE: case BPF_PSEUDO_MAP_IDX: if (bpfptr_is_null(env->fd_array)) { verbose(env, "fd_idx without fd_array is invalid\n"); return -EPROTO; } if (copy_from_bpfptr_offset(&fd, env->fd_array, insn[0].imm * sizeof(fd), sizeof(fd))) return -EFAULT; break; default: fd = insn[0].imm; break; } map_idx = add_used_map_from_fd(env, fd, &reused); if (map_idx < 0) return map_idx; map = env->used_maps[map_idx]; aux = &env->insn_aux_data[i]; aux->map_index = map_idx; err = check_map_prog_compatibility(env, map, env->prog); if (err) return err; if (insn[0].src_reg == BPF_PSEUDO_MAP_FD || insn[0].src_reg == BPF_PSEUDO_MAP_IDX) { addr = (unsigned long)map; } else { u32 off = insn[1].imm; if (off >= BPF_MAX_VAR_OFF) { verbose(env, "direct value offset of %u is not allowed\n", off); return -EINVAL; } if (!map->ops->map_direct_value_addr) { verbose(env, "no direct value access support for this map type\n"); return -EINVAL; } err = map->ops->map_direct_value_addr(map, &addr, off); if (err) { verbose(env, "invalid access to map value pointer, value_size=%u off=%u\n", map->value_size, off); return err; } aux->map_off = off; addr += off; } insn[0].imm = (u32)addr; insn[1].imm = addr >> 32; /* proceed with extra checks only if its newly added used map */ if (reused) goto next_insn; if (bpf_map_is_cgroup_storage(map) && bpf_cgroup_storage_assign(env->prog->aux, map)) { verbose(env, "only one cgroup storage of each type is allowed\n"); return -EBUSY; } if (map->map_type == BPF_MAP_TYPE_ARENA) { if (env->prog->aux->arena) { verbose(env, "Only one arena per program\n"); return -EBUSY; } if (!env->allow_ptr_leaks || !env->bpf_capable) { verbose(env, "CAP_BPF and CAP_PERFMON are required to use arena\n"); return -EPERM; } if (!env->prog->jit_requested) { verbose(env, "JIT is required to use arena\n"); return -EOPNOTSUPP; } if (!bpf_jit_supports_arena()) { verbose(env, "JIT doesn't support arena\n"); return -EOPNOTSUPP; } env->prog->aux->arena = (void *)map; if (!bpf_arena_get_user_vm_start(env->prog->aux->arena)) { verbose(env, "arena's user address must be set via map_extra or mmap()\n"); return -EINVAL; } } next_insn: insn++; i++; continue; } /* Basic sanity check before we invest more work here. */ if (!bpf_opcode_in_insntable(insn->code)) { verbose(env, "unknown opcode %02x\n", insn->code); return -EINVAL; } } /* now all pseudo BPF_LD_IMM64 instructions load valid * 'struct bpf_map *' into a register instead of user map_fd. * These pointers will be used later by verifier to validate map access. */ return 0; } /* drop refcnt of maps used by the rejected program */ static void release_maps(struct bpf_verifier_env *env) { __bpf_free_used_maps(env->prog->aux, env->used_maps, env->used_map_cnt); } /* drop refcnt of maps used by the rejected program */ static void release_btfs(struct bpf_verifier_env *env) { __bpf_free_used_btfs(env->used_btfs, env->used_btf_cnt); } /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) { struct bpf_insn *insn = env->prog->insnsi; int insn_cnt = env->prog->len; int i; for (i = 0; i < insn_cnt; i++, insn++) { if (insn->code != (BPF_LD | BPF_IMM | BPF_DW)) continue; if (insn->src_reg == BPF_PSEUDO_FUNC) continue; insn->src_reg = 0; } } /* single env->prog->insni[off] instruction was replaced with the range * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying * [0, off) and [off, end) to new locations, so the patched range stays zero */ static void adjust_insn_aux_data(struct bpf_verifier_env *env, struct bpf_insn_aux_data *new_data, struct bpf_prog *new_prog, u32 off, u32 cnt) { struct bpf_insn_aux_data *old_data = env->insn_aux_data; struct bpf_insn *insn = new_prog->insnsi; u32 old_seen = old_data[off].seen; u32 prog_len; int i; /* aux info at OFF always needs adjustment, no matter fast path * (cnt == 1) is taken or not. There is no guarantee INSN at OFF is the * original insn at old prog. */ old_data[off].zext_dst = insn_has_def32(env, insn + off + cnt - 1); if (cnt == 1) return; prog_len = new_prog->len; memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off); memcpy(new_data + off + cnt - 1, old_data + off, sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1)); for (i = off; i < off + cnt - 1; i++) { /* Expand insni[off]'s seen count to the patched range. */ new_data[i].seen = old_seen; new_data[i].zext_dst = insn_has_def32(env, insn + i); } env->insn_aux_data = new_data; vfree(old_data); } static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len) { int i; if (len == 1) return; /* NOTE: fake 'exit' subprog should be updated as well. */ for (i = 0; i <= env->subprog_cnt; i++) { if (env->subprog_info[i].start <= off) continue; env->subprog_info[i].start += len - 1; } } static void adjust_poke_descs(struct bpf_prog *prog, u32 off, u32 len) { struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab; int i, sz = prog->aux->size_poke_tab; struct bpf_jit_poke_descriptor *desc; for (i = 0; i < sz; i++) { desc = &tab[i]; if (desc->insn_idx <= off) continue; desc->insn_idx += len - 1; } } static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, const struct bpf_insn *patch, u32 len) { struct bpf_prog *new_prog; struct bpf_insn_aux_data *new_data = NULL; if (len > 1) { new_data = vzalloc(array_size(env->prog->len + len - 1, sizeof(struct bpf_insn_aux_data))); if (!new_data) return NULL; } new_prog = bpf_patch_insn_single(env->prog, off, patch, len); if (IS_ERR(new_prog)) { if (PTR_ERR(new_prog) == -ERANGE) verbose(env, "insn %d cannot be patched due to 16-bit range\n", env->insn_aux_data[off].orig_idx); vfree(new_data); return NULL; } adjust_insn_aux_data(env, new_data, new_prog, off, len); adjust_subprog_starts(env, off, len); adjust_poke_descs(new_prog, off, len); return new_prog; } /* * For all jmp insns in a given 'prog' that point to 'tgt_idx' insn adjust the * jump offset by 'delta'. */ static int adjust_jmp_off(struct bpf_prog *prog, u32 tgt_idx, u32 delta) { struct bpf_insn *insn = prog->insnsi; u32 insn_cnt = prog->len, i; s32 imm; s16 off; for (i = 0; i < insn_cnt; i++, insn++) { u8 code = insn->code; if (tgt_idx <= i && i < tgt_idx + delta) continue; if ((BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32) || BPF_OP(code) == BPF_CALL || BPF_OP(code) == BPF_EXIT) continue; if (insn->code == (BPF_JMP32 | BPF_JA)) { if (i + 1 + insn->imm != tgt_idx) continue; if (check_add_overflow(insn->imm, delta, &imm)) return -ERANGE; insn->imm = imm; } else { if (i + 1 + insn->off != tgt_idx) continue; if (check_add_overflow(insn->off, delta, &off)) return -ERANGE; insn->off = off; } } return 0; } static int adjust_subprog_starts_after_remove(struct bpf_verifier_env *env, u32 off, u32 cnt) { int i, j; /* find first prog starting at or after off (first to remove) */ for (i = 0; i < env->subprog_cnt; i++) if (env->subprog_info[i].start >= off) break; /* find first prog starting at or after off + cnt (first to stay) */ for (j = i; j < env->subprog_cnt; j++) if (env->subprog_info[j].start >= off + cnt) break; /* if j doesn't start exactly at off + cnt, we are just removing * the front of previous prog */ if (env->subprog_info[j].start != off + cnt) j--; if (j > i) { struct bpf_prog_aux *aux = env->prog->aux; int move; /* move fake 'exit' subprog as well */ move = env->subprog_cnt + 1 - j; memmove(env->subprog_info + i, env->subprog_info + j, sizeof(*env->subprog_info) * move); env->subprog_cnt -= j - i; /* remove func_info */ if (aux->func_info) { move = aux->func_info_cnt - j; memmove(aux->func_info + i, aux->func_info + j, sizeof(*aux->func_info) * move); aux->func_info_cnt -= j - i; /* func_info->insn_off is set after all code rewrites, * in adjust_btf_func() - no need to adjust */ } } else { /* convert i from "first prog to remove" to "first to adjust" */ if (env->subprog_info[i].start == off) i++; } /* update fake 'exit' subprog as well */ for (; i <= env->subprog_cnt; i++) env->subprog_info[i].start -= cnt; return 0; } static int bpf_adj_linfo_after_remove(struct bpf_verifier_env *env, u32 off, u32 cnt) { struct bpf_prog *prog = env->prog; u32 i, l_off, l_cnt, nr_linfo; struct bpf_line_info *linfo; nr_linfo = prog->aux->nr_linfo; if (!nr_linfo) return 0; linfo = prog->aux->linfo; /* find first line info to remove, count lines to be removed */ for (i = 0; i < nr_linfo; i++) if (linfo[i].insn_off >= off) break; l_off = i; l_cnt = 0; for (; i < nr_linfo; i++) if (linfo[i].insn_off < off + cnt) l_cnt++; else break; /* First live insn doesn't match first live linfo, it needs to "inherit" * last removed linfo. prog is already modified, so prog->len == off * means no live instructions after (tail of the program was removed). */ if (prog->len != off && l_cnt && (i == nr_linfo || linfo[i].insn_off != off + cnt)) { l_cnt--; linfo[--i].insn_off = off + cnt; } /* remove the line info which refer to the removed instructions */ if (l_cnt) { memmove(linfo + l_off, linfo + i, sizeof(*linfo) * (nr_linfo - i)); prog->aux->nr_linfo -= l_cnt; nr_linfo = prog->aux->nr_linfo; } /* pull all linfo[i].insn_off >= off + cnt in by cnt */ for (i = l_off; i < nr_linfo; i++) linfo[i].insn_off -= cnt; /* fix up all subprogs (incl. 'exit') which start >= off */ for (i = 0; i <= env->subprog_cnt; i++) if (env->subprog_info[i].linfo_idx > l_off) { /* program may have started in the removed region but * may not be fully removed */ if (env->subprog_info[i].linfo_idx >= l_off + l_cnt) env->subprog_info[i].linfo_idx -= l_cnt; else env->subprog_info[i].linfo_idx = l_off; } return 0; } static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt) { struct bpf_insn_aux_data *aux_data = env->insn_aux_data; unsigned int orig_prog_len = env->prog->len; int err; if (bpf_prog_is_offloaded(env->prog->aux)) bpf_prog_offload_remove_insns(env, off, cnt); err = bpf_remove_insns(env->prog, off, cnt); if (err) return err; err = adjust_subprog_starts_after_remove(env, off, cnt); if (err) return err; err = bpf_adj_linfo_after_remove(env, off, cnt); if (err) return err; memmove(aux_data + off, aux_data + off + cnt, sizeof(*aux_data) * (orig_prog_len - off - cnt)); return 0; } /* The verifier does more data flow analysis than llvm and will not * explore branches that are dead at run time. Malicious programs can * have dead code too. Therefore replace all dead at-run-time code * with 'ja -1'. * * Just nops are not optimal, e.g. if they would sit at the end of the * program and through another bug we would manage to jump there, then * we'd execute beyond program memory otherwise. Returning exception * code also wouldn't work since we can have subprogs where the dead * code could be located. */ static void sanitize_dead_code(struct bpf_verifier_env *env) { struct bpf_insn_aux_data *aux_data = env->insn_aux_data; struct bpf_insn trap = BPF_JMP_IMM(BPF_JA, 0, 0, -1); struct bpf_insn *insn = env->prog->insnsi; const int insn_cnt = env->prog->len; int i; for (i = 0; i < insn_cnt; i++) { if (aux_data[i].seen) continue; memcpy(insn + i, &trap, sizeof(trap)); aux_data[i].zext_dst = false; } } static bool insn_is_cond_jump(u8 code) { u8 op; op = BPF_OP(code); if (BPF_CLASS(code) == BPF_JMP32) return op != BPF_JA; if (BPF_CLASS(code) != BPF_JMP) return false; return op != BPF_JA && op != BPF_EXIT && op != BPF_CALL; } static void opt_hard_wire_dead_code_branches(struct bpf_verifier_env *env) { struct bpf_insn_aux_data *aux_data = env->insn_aux_data; struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0); struct bpf_insn *insn = env->prog->insnsi; const int insn_cnt = env->prog->len; int i; for (i = 0; i < insn_cnt; i++, insn++) { if (!insn_is_cond_jump(insn->code)) continue; if (!aux_data[i + 1].seen) ja.off = insn->off; else if (!aux_data[i + 1 + insn->off].seen) ja.off = 0; else continue; if (bpf_prog_is_offloaded(env->prog->aux)) bpf_prog_offload_replace_insn(env, i, &ja); memcpy(insn, &ja, sizeof(ja)); } } static int opt_remove_dead_code(struct bpf_verifier_env *env) { struct bpf_insn_aux_data *aux_data = env->insn_aux_data; int insn_cnt = env->prog->len; int i, err; for (i = 0; i < insn_cnt; i++) { int j; j = 0; while (i + j < insn_cnt && !aux_data[i + j].seen) j++; if (!j) continue; err = verifier_remove_insns(env, i, j); if (err) return err; insn_cnt = env->prog->len; } return 0; } static const struct bpf_insn NOP = BPF_JMP_IMM(BPF_JA, 0, 0, 0); static int opt_remove_nops(struct bpf_verifier_env *env) { const struct bpf_insn ja = NOP; struct bpf_insn *insn = env->prog->insnsi; int insn_cnt = env->prog->len; int i, err; for (i = 0; i < insn_cnt; i++) { if (memcmp(&insn[i], &ja, sizeof(ja))) continue; err = verifier_remove_insns(env, i, 1); if (err) return err; insn_cnt--; i--; } return 0; } static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env, const union bpf_attr *attr) { struct bpf_insn *patch, zext_patch[2], rnd_hi32_patch[4]; struct bpf_insn_aux_data *aux = env->insn_aux_data; int i, patch_len, delta = 0, len = env->prog->len; struct bpf_insn *insns = env->prog->insnsi; struct bpf_prog *new_prog; bool rnd_hi32; rnd_hi32 = attr->prog_flags & BPF_F_TEST_RND_HI32; zext_patch[1] = BPF_ZEXT_REG(0); rnd_hi32_patch[1] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, 0); rnd_hi32_patch[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32); rnd_hi32_patch[3] = BPF_ALU64_REG(BPF_OR, 0, BPF_REG_AX); for (i = 0; i < len; i++) { int adj_idx = i + delta; struct bpf_insn insn; int load_reg; insn = insns[adj_idx]; load_reg = insn_def_regno(&insn); if (!aux[adj_idx].zext_dst) { u8 code, class; u32 imm_rnd; if (!rnd_hi32) continue; code = insn.code; class = BPF_CLASS(code); if (load_reg == -1) continue; /* NOTE: arg "reg" (the fourth one) is only used for * BPF_STX + SRC_OP, so it is safe to pass NULL * here. */ if (is_reg64(env, &insn, load_reg, NULL, DST_OP)) { if (class == BPF_LD && BPF_MODE(code) == BPF_IMM) i++; continue; } /* ctx load could be transformed into wider load. */ if (class == BPF_LDX && aux[adj_idx].ptr_type == PTR_TO_CTX) continue; imm_rnd = get_random_u32(); rnd_hi32_patch[0] = insn; rnd_hi32_patch[1].imm = imm_rnd; rnd_hi32_patch[3].dst_reg = load_reg; patch = rnd_hi32_patch; patch_len = 4; goto apply_patch_buffer; } /* Add in an zero-extend instruction if a) the JIT has requested * it or b) it's a CMPXCHG. * * The latter is because: BPF_CMPXCHG always loads a value into * R0, therefore always zero-extends. However some archs' * equivalent instruction only does this load when the * comparison is successful. This detail of CMPXCHG is * orthogonal to the general zero-extension behaviour of the * CPU, so it's treated independently of bpf_jit_needs_zext. */ if (!bpf_jit_needs_zext() && !is_cmpxchg_insn(&insn)) continue; /* Zero-extension is done by the caller. */ if (bpf_pseudo_kfunc_call(&insn)) continue; if (WARN_ON(load_reg == -1)) { verbose(env, "verifier bug. zext_dst is set, but no reg is defined\n"); return -EFAULT; } zext_patch[0] = insn; zext_patch[1].dst_reg = load_reg; zext_patch[1].src_reg = load_reg; patch = zext_patch; patch_len = 2; apply_patch_buffer: new_prog = bpf_patch_insn_data(env, adj_idx, patch, patch_len); if (!new_prog) return -ENOMEM; env->prog = new_prog; insns = new_prog->insnsi; aux = env->insn_aux_data; delta += patch_len - 1; } return 0; } /* convert load instructions that access fields of a context type into a * sequence of instructions that access fields of the underlying structure: * struct __sk_buff -> struct sk_buff * struct bpf_sock_ops -> struct sock */ static int convert_ctx_accesses(struct bpf_verifier_env *env) { struct bpf_subprog_info *subprogs = env->subprog_info; const struct bpf_verifier_ops *ops = env->ops; int i, cnt, size, ctx_field_size, delta = 0, epilogue_cnt = 0; const int insn_cnt = env->prog->len; struct bpf_insn *epilogue_buf = env->epilogue_buf; struct bpf_insn *insn_buf = env->insn_buf; struct bpf_insn *insn; u32 target_size, size_default, off; struct bpf_prog *new_prog; enum bpf_access_type type; bool is_narrower_load; int epilogue_idx = 0; if (ops->gen_epilogue) { epilogue_cnt = ops->gen_epilogue(epilogue_buf, env->prog, -(subprogs[0].stack_depth + 8)); if (epilogue_cnt >= INSN_BUF_SIZE) { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; } else if (epilogue_cnt) { /* Save the ARG_PTR_TO_CTX for the epilogue to use */ cnt = 0; subprogs[0].stack_depth += 8; insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_FP, BPF_REG_1, -subprogs[0].stack_depth); insn_buf[cnt++] = env->prog->insnsi[0]; new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt); if (!new_prog) return -ENOMEM; env->prog = new_prog; delta += cnt - 1; } } if (ops->gen_prologue || env->seen_direct_write) { if (!ops->gen_prologue) { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; } cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, env->prog); if (cnt >= INSN_BUF_SIZE) { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; } else if (cnt) { new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt); if (!new_prog) return -ENOMEM; env->prog = new_prog; delta += cnt - 1; } } if (delta) WARN_ON(adjust_jmp_off(env->prog, 0, delta)); if (bpf_prog_is_offloaded(env->prog->aux)) return 0; insn = env->prog->insnsi + delta; for (i = 0; i < insn_cnt; i++, insn++) { bpf_convert_ctx_access_t convert_ctx_access; u8 mode; if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || insn->code == (BPF_LDX | BPF_MEM | BPF_H) || insn->code == (BPF_LDX | BPF_MEM | BPF_W) || insn->code == (BPF_LDX | BPF_MEM | BPF_DW) || insn->code == (BPF_LDX | BPF_MEMSX | BPF_B) || insn->code == (BPF_LDX | BPF_MEMSX | BPF_H) || insn->code == (BPF_LDX | BPF_MEMSX | BPF_W)) { type = BPF_READ; } else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || insn->code == (BPF_STX | BPF_MEM | BPF_H) || insn->code == (BPF_STX | BPF_MEM | BPF_W) || insn->code == (BPF_STX | BPF_MEM | BPF_DW) || insn->code == (BPF_ST | BPF_MEM | BPF_B) || insn->code == (BPF_ST | BPF_MEM | BPF_H) || insn->code == (BPF_ST | BPF_MEM | BPF_W) || insn->code == (BPF_ST | BPF_MEM | BPF_DW)) { type = BPF_WRITE; } else if ((insn->code == (BPF_STX | BPF_ATOMIC | BPF_W) || insn->code == (BPF_STX | BPF_ATOMIC | BPF_DW)) && env->insn_aux_data[i + delta].ptr_type == PTR_TO_ARENA) { insn->code = BPF_STX | BPF_PROBE_ATOMIC | BPF_SIZE(insn->code); env->prog->aux->num_exentries++; continue; } else if (insn->code == (BPF_JMP | BPF_EXIT) && epilogue_cnt && i + delta < subprogs[1].start) { /* Generate epilogue for the main prog */ if (epilogue_idx) { /* jump back to the earlier generated epilogue */ insn_buf[0] = BPF_JMP32_A(epilogue_idx - i - delta - 1); cnt = 1; } else { memcpy(insn_buf, epilogue_buf, epilogue_cnt * sizeof(*epilogue_buf)); cnt = epilogue_cnt; /* epilogue_idx cannot be 0. It must have at * least one ctx ptr saving insn before the * epilogue. */ epilogue_idx = i + delta; } goto patch_insn_buf; } else { continue; } if (type == BPF_WRITE && env->insn_aux_data[i + delta].sanitize_stack_spill) { struct bpf_insn patch[] = { *insn, BPF_ST_NOSPEC(), }; cnt = ARRAY_SIZE(patch); new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = new_prog; insn = new_prog->insnsi + i + delta; continue; } switch ((int)env->insn_aux_data[i + delta].ptr_type) { case PTR_TO_CTX: if (!ops->convert_ctx_access) continue; convert_ctx_access = ops->convert_ctx_access; break; case PTR_TO_SOCKET: case PTR_TO_SOCK_COMMON: convert_ctx_access = bpf_sock_convert_ctx_access; break; case PTR_TO_TCP_SOCK: convert_ctx_access = bpf_tcp_sock_convert_ctx_access; break; case PTR_TO_XDP_SOCK: convert_ctx_access = bpf_xdp_sock_convert_ctx_access; break; case PTR_TO_BTF_ID: case PTR_TO_BTF_ID | PTR_UNTRUSTED: /* PTR_TO_BTF_ID | MEM_ALLOC always has a valid lifetime, unlike * PTR_TO_BTF_ID, and an active ref_obj_id, but the same cannot * be said once it is marked PTR_UNTRUSTED, hence we must handle * any faults for loads into such types. BPF_WRITE is disallowed * for this case. */ case PTR_TO_BTF_ID | MEM_ALLOC | PTR_UNTRUSTED: if (type == BPF_READ) { if (BPF_MODE(insn->code) == BPF_MEM) insn->code = BPF_LDX | BPF_PROBE_MEM | BPF_SIZE((insn)->code); else insn->code = BPF_LDX | BPF_PROBE_MEMSX | BPF_SIZE((insn)->code); env->prog->aux->num_exentries++; } continue; case PTR_TO_ARENA: if (BPF_MODE(insn->code) == BPF_MEMSX) { verbose(env, "sign extending loads from arena are not supported yet\n"); return -EOPNOTSUPP; } insn->code = BPF_CLASS(insn->code) | BPF_PROBE_MEM32 | BPF_SIZE(insn->code); env->prog->aux->num_exentries++; continue; default: continue; } ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; size = BPF_LDST_BYTES(insn); mode = BPF_MODE(insn->code); /* If the read access is a narrower load of the field, * convert to a 4/8-byte load, to minimum program type specific * convert_ctx_access changes. If conversion is successful, * we will apply proper mask to the result. */ is_narrower_load = size < ctx_field_size; size_default = bpf_ctx_off_adjust_machine(ctx_field_size); off = insn->off; if (is_narrower_load) { u8 size_code; if (type == BPF_WRITE) { verbose(env, "bpf verifier narrow ctx access misconfigured\n"); return -EINVAL; } size_code = BPF_H; if (ctx_field_size == 4) size_code = BPF_W; else if (ctx_field_size == 8) size_code = BPF_DW; insn->off = off & ~(size_default - 1); insn->code = BPF_LDX | BPF_MEM | size_code; } target_size = 0; cnt = convert_ctx_access(type, insn, insn_buf, env->prog, &target_size); if (cnt == 0 || cnt >= INSN_BUF_SIZE || (ctx_field_size && !target_size)) { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; } if (is_narrower_load && size < target_size) { u8 shift = bpf_ctx_narrow_access_offset( off, size, size_default) * 8; if (shift && cnt + 1 >= INSN_BUF_SIZE) { verbose(env, "bpf verifier narrow ctx load misconfigured\n"); return -EINVAL; } if (ctx_field_size <= 4) { if (shift) insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH, insn->dst_reg, shift); insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, (1 << size * 8) - 1); } else { if (shift) insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH, insn->dst_reg, shift); insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, (1ULL << size * 8) - 1); } } if (mode == BPF_MEMSX) insn_buf[cnt++] = BPF_RAW_INSN(BPF_ALU64 | BPF_MOV | BPF_X, insn->dst_reg, insn->dst_reg, size * 8, 0); patch_insn_buf: new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; /* keep walking new program and skip insns we just inserted */ env->prog = new_prog; insn = new_prog->insnsi + i + delta; } return 0; } static int jit_subprogs(struct bpf_verifier_env *env) { struct bpf_prog *prog = env->prog, **func, *tmp; int i, j, subprog_start, subprog_end = 0, len, subprog; struct bpf_map *map_ptr; struct bpf_insn *insn; void *old_bpf_func; int err, num_exentries; if (env->subprog_cnt <= 1) return 0; for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn)) continue; /* Upon error here we cannot fall back to interpreter but * need a hard reject of the program. Thus -EFAULT is * propagated in any case. */ subprog = find_subprog(env, i + insn->imm + 1); if (subprog < 0) { WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", i + insn->imm + 1); return -EFAULT; } /* temporarily remember subprog id inside insn instead of * aux_data, since next loop will split up all insns into funcs */ insn->off = subprog; /* remember original imm in case JIT fails and fallback * to interpreter will be needed */ env->insn_aux_data[i].call_imm = insn->imm; /* point imm to __bpf_call_base+1 from JITs point of view */ insn->imm = 1; if (bpf_pseudo_func(insn)) { #if defined(MODULES_VADDR) u64 addr = MODULES_VADDR; #else u64 addr = VMALLOC_START; #endif /* jit (e.g. x86_64) may emit fewer instructions * if it learns a u32 imm is the same as a u64 imm. * Set close enough to possible prog address. */ insn[0].imm = (u32)addr; insn[1].imm = addr >> 32; } } err = bpf_prog_alloc_jited_linfo(prog); if (err) goto out_undo_insn; err = -ENOMEM; func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL); if (!func) goto out_undo_insn; for (i = 0; i < env->subprog_cnt; i++) { subprog_start = subprog_end; subprog_end = env->subprog_info[i + 1].start; len = subprog_end - subprog_start; /* bpf_prog_run() doesn't call subprogs directly, * hence main prog stats include the runtime of subprogs. * subprogs don't have IDs and not reachable via prog_get_next_id * func[i]->stats will never be accessed and stays NULL */ func[i] = bpf_prog_alloc_no_stats(bpf_prog_size(len), GFP_USER); if (!func[i]) goto out_free; memcpy(func[i]->insnsi, &prog->insnsi[subprog_start], len * sizeof(struct bpf_insn)); func[i]->type = prog->type; func[i]->len = len; if (bpf_prog_calc_tag(func[i])) goto out_free; func[i]->is_func = 1; func[i]->sleepable = prog->sleepable; func[i]->aux->func_idx = i; /* Below members will be freed only at prog->aux */ func[i]->aux->btf = prog->aux->btf; func[i]->aux->func_info = prog->aux->func_info; func[i]->aux->func_info_cnt = prog->aux->func_info_cnt; func[i]->aux->poke_tab = prog->aux->poke_tab; func[i]->aux->size_poke_tab = prog->aux->size_poke_tab; for (j = 0; j < prog->aux->size_poke_tab; j++) { struct bpf_jit_poke_descriptor *poke; poke = &prog->aux->poke_tab[j]; if (poke->insn_idx < subprog_end && poke->insn_idx >= subprog_start) poke->aux = func[i]->aux; } func[i]->aux->name[0] = 'F'; func[i]->aux->stack_depth = env->subprog_info[i].stack_depth; if (env->subprog_info[i].priv_stack_mode == PRIV_STACK_ADAPTIVE) func[i]->aux->jits_use_priv_stack = true; func[i]->jit_requested = 1; func[i]->blinding_requested = prog->blinding_requested; func[i]->aux->kfunc_tab = prog->aux->kfunc_tab; func[i]->aux->kfunc_btf_tab = prog->aux->kfunc_btf_tab; func[i]->aux->linfo = prog->aux->linfo; func[i]->aux->nr_linfo = prog->aux->nr_linfo; func[i]->aux->jited_linfo = prog->aux->jited_linfo; func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx; func[i]->aux->arena = prog->aux->arena; num_exentries = 0; insn = func[i]->insnsi; for (j = 0; j < func[i]->len; j++, insn++) { if (BPF_CLASS(insn->code) == BPF_LDX && (BPF_MODE(insn->code) == BPF_PROBE_MEM || BPF_MODE(insn->code) == BPF_PROBE_MEM32 || BPF_MODE(insn->code) == BPF_PROBE_MEMSX)) num_exentries++; if ((BPF_CLASS(insn->code) == BPF_STX || BPF_CLASS(insn->code) == BPF_ST) && BPF_MODE(insn->code) == BPF_PROBE_MEM32) num_exentries++; if (BPF_CLASS(insn->code) == BPF_STX && BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) num_exentries++; } func[i]->aux->num_exentries = num_exentries; func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable; func[i]->aux->exception_cb = env->subprog_info[i].is_exception_cb; func[i]->aux->changes_pkt_data = env->subprog_info[i].changes_pkt_data; if (!i) func[i]->aux->exception_boundary = env->seen_exception; func[i] = bpf_int_jit_compile(func[i]); if (!func[i]->jited) { err = -ENOTSUPP; goto out_free; } cond_resched(); } /* at this point all bpf functions were successfully JITed * now populate all bpf_calls with correct addresses and * run last pass of JIT */ for (i = 0; i < env->subprog_cnt; i++) { insn = func[i]->insnsi; for (j = 0; j < func[i]->len; j++, insn++) { if (bpf_pseudo_func(insn)) { subprog = insn->off; insn[0].imm = (u32)(long)func[subprog]->bpf_func; insn[1].imm = ((u64)(long)func[subprog]->bpf_func) >> 32; continue; } if (!bpf_pseudo_call(insn)) continue; subprog = insn->off; insn->imm = BPF_CALL_IMM(func[subprog]->bpf_func); } /* we use the aux data to keep a list of the start addresses * of the JITed images for each function in the program * * for some architectures, such as powerpc64, the imm field * might not be large enough to hold the offset of the start * address of the callee's JITed image from __bpf_call_base * * in such cases, we can lookup the start address of a callee * by using its subprog id, available from the off field of * the call instruction, as an index for this list */ func[i]->aux->func = func; func[i]->aux->func_cnt = env->subprog_cnt - env->hidden_subprog_cnt; func[i]->aux->real_func_cnt = env->subprog_cnt; } for (i = 0; i < env->subprog_cnt; i++) { old_bpf_func = func[i]->bpf_func; tmp = bpf_int_jit_compile(func[i]); if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) { verbose(env, "JIT doesn't support bpf-to-bpf calls\n"); err = -ENOTSUPP; goto out_free; } cond_resched(); } /* finally lock prog and jit images for all functions and * populate kallsysm. Begin at the first subprogram, since * bpf_prog_load will add the kallsyms for the main program. */ for (i = 1; i < env->subprog_cnt; i++) { err = bpf_prog_lock_ro(func[i]); if (err) goto out_free; } for (i = 1; i < env->subprog_cnt; i++) bpf_prog_kallsyms_add(func[i]); /* Last step: make now unused interpreter insns from main * prog consistent for later dump requests, so they can * later look the same as if they were interpreted only. */ for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { if (bpf_pseudo_func(insn)) { insn[0].imm = env->insn_aux_data[i].call_imm; insn[1].imm = insn->off; insn->off = 0; continue; } if (!bpf_pseudo_call(insn)) continue; insn->off = env->insn_aux_data[i].call_imm; subprog = find_subprog(env, i + insn->off + 1); insn->imm = subprog; } prog->jited = 1; prog->bpf_func = func[0]->bpf_func; prog->jited_len = func[0]->jited_len; prog->aux->extable = func[0]->aux->extable; prog->aux->num_exentries = func[0]->aux->num_exentries; prog->aux->func = func; prog->aux->func_cnt = env->subprog_cnt - env->hidden_subprog_cnt; prog->aux->real_func_cnt = env->subprog_cnt; prog->aux->bpf_exception_cb = (void *)func[env->exception_callback_subprog]->bpf_func; prog->aux->exception_boundary = func[0]->aux->exception_boundary; bpf_prog_jit_attempt_done(prog); return 0; out_free: /* We failed JIT'ing, so at this point we need to unregister poke * descriptors from subprogs, so that kernel is not attempting to * patch it anymore as we're freeing the subprog JIT memory. */ for (i = 0; i < prog->aux->size_poke_tab; i++) { map_ptr = prog->aux->poke_tab[i].tail_call.map; map_ptr->ops->map_poke_untrack(map_ptr, prog->aux); } /* At this point we're guaranteed that poke descriptors are not * live anymore. We can just unlink its descriptor table as it's * released with the main prog. */ for (i = 0; i < env->subprog_cnt; i++) { if (!func[i]) continue; func[i]->aux->poke_tab = NULL; bpf_jit_free(func[i]); } kfree(func); out_undo_insn: /* cleanup main prog to be interpreted */ prog->jit_requested = 0; prog->blinding_requested = 0; for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { if (!bpf_pseudo_call(insn)) continue; insn->off = 0; insn->imm = env->insn_aux_data[i].call_imm; } bpf_prog_jit_attempt_done(prog); return err; } static int fixup_call_args(struct bpf_verifier_env *env) { #ifndef CONFIG_BPF_JIT_ALWAYS_ON struct bpf_prog *prog = env->prog; struct bpf_insn *insn = prog->insnsi; bool has_kfunc_call = bpf_prog_has_kfunc_call(prog); int i, depth; #endif int err = 0; if (env->prog->jit_requested && !bpf_prog_is_offloaded(env->prog->aux)) { err = jit_subprogs(env); if (err == 0) return 0; if (err == -EFAULT) return err; } #ifndef CONFIG_BPF_JIT_ALWAYS_ON if (has_kfunc_call) { verbose(env, "calling kernel functions are not allowed in non-JITed programs\n"); return -EINVAL; } if (env->subprog_cnt > 1 && env->prog->aux->tail_call_reachable) { /* When JIT fails the progs with bpf2bpf calls and tail_calls * have to be rejected, since interpreter doesn't support them yet. */ verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n"); return -EINVAL; } for (i = 0; i < prog->len; i++, insn++) { if (bpf_pseudo_func(insn)) { /* When JIT fails the progs with callback calls * have to be rejected, since interpreter doesn't support them yet. */ verbose(env, "callbacks are not allowed in non-JITed programs\n"); return -EINVAL; } if (!bpf_pseudo_call(insn)) continue; depth = get_callee_stack_depth(env, insn, i); if (depth < 0) return depth; bpf_patch_call_args(insn, depth); } err = 0; #endif return err; } /* replace a generic kfunc with a specialized version if necessary */ static void specialize_kfunc(struct bpf_verifier_env *env, u32 func_id, u16 offset, unsigned long *addr) { struct bpf_prog *prog = env->prog; bool seen_direct_write; void *xdp_kfunc; bool is_rdonly; if (bpf_dev_bound_kfunc_id(func_id)) { xdp_kfunc = bpf_dev_bound_resolve_kfunc(prog, func_id); if (xdp_kfunc) { *addr = (unsigned long)xdp_kfunc; return; } /* fallback to default kfunc when not supported by netdev */ } if (offset) return; if (func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) { seen_direct_write = env->seen_direct_write; is_rdonly = !may_access_direct_pkt_data(env, NULL, BPF_WRITE); if (is_rdonly) *addr = (unsigned long)bpf_dynptr_from_skb_rdonly; /* restore env->seen_direct_write to its original value, since * may_access_direct_pkt_data mutates it */ env->seen_direct_write = seen_direct_write; } } static void __fixup_collection_insert_kfunc(struct bpf_insn_aux_data *insn_aux, u16 struct_meta_reg, u16 node_offset_reg, struct bpf_insn *insn, struct bpf_insn *insn_buf, int *cnt) { struct btf_struct_meta *kptr_struct_meta = insn_aux->kptr_struct_meta; struct bpf_insn addr[2] = { BPF_LD_IMM64(struct_meta_reg, (long)kptr_struct_meta) }; insn_buf[0] = addr[0]; insn_buf[1] = addr[1]; insn_buf[2] = BPF_MOV64_IMM(node_offset_reg, insn_aux->insert_off); insn_buf[3] = *insn; *cnt = 4; } static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, struct bpf_insn *insn_buf, int insn_idx, int *cnt) { const struct bpf_kfunc_desc *desc; if (!insn->imm) { verbose(env, "invalid kernel function call not eliminated in verifier pass\n"); return -EINVAL; } *cnt = 0; /* insn->imm has the btf func_id. Replace it with an offset relative to * __bpf_call_base, unless the JIT needs to call functions that are * further than 32 bits away (bpf_jit_supports_far_kfunc_call()). */ desc = find_kfunc_desc(env->prog, insn->imm, insn->off); if (!desc) { verbose(env, "verifier internal error: kernel function descriptor not found for func_id %u\n", insn->imm); return -EFAULT; } if (!bpf_jit_supports_far_kfunc_call()) insn->imm = BPF_CALL_IMM(desc->addr); if (insn->off) return 0; if (desc->func_id == special_kfunc_list[KF_bpf_obj_new_impl] || desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta; struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) }; u64 obj_new_size = env->insn_aux_data[insn_idx].obj_new_size; if (desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl] && kptr_struct_meta) { verbose(env, "verifier internal error: NULL kptr_struct_meta expected at insn_idx %d\n", insn_idx); return -EFAULT; } insn_buf[0] = BPF_MOV64_IMM(BPF_REG_1, obj_new_size); insn_buf[1] = addr[0]; insn_buf[2] = addr[1]; insn_buf[3] = *insn; *cnt = 4; } else if (desc->func_id == special_kfunc_list[KF_bpf_obj_drop_impl] || desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl] || desc->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]) { struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta; struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) }; if (desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl] && kptr_struct_meta) { verbose(env, "verifier internal error: NULL kptr_struct_meta expected at insn_idx %d\n", insn_idx); return -EFAULT; } if (desc->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl] && !kptr_struct_meta) { verbose(env, "verifier internal error: kptr_struct_meta expected at insn_idx %d\n", insn_idx); return -EFAULT; } insn_buf[0] = addr[0]; insn_buf[1] = addr[1]; insn_buf[2] = *insn; *cnt = 3; } else if (desc->func_id == special_kfunc_list[KF_bpf_list_push_back_impl] || desc->func_id == special_kfunc_list[KF_bpf_list_push_front_impl] || desc->func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) { struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta; int struct_meta_reg = BPF_REG_3; int node_offset_reg = BPF_REG_4; /* rbtree_add has extra 'less' arg, so args-to-fixup are in diff regs */ if (desc->func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) { struct_meta_reg = BPF_REG_4; node_offset_reg = BPF_REG_5; } if (!kptr_struct_meta) { verbose(env, "verifier internal error: kptr_struct_meta expected at insn_idx %d\n", insn_idx); return -EFAULT; } __fixup_collection_insert_kfunc(&env->insn_aux_data[insn_idx], struct_meta_reg, node_offset_reg, insn, insn_buf, cnt); } else if (desc->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx] || desc->func_id == special_kfunc_list[KF_bpf_rdonly_cast]) { insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1); *cnt = 1; } else if (is_bpf_wq_set_callback_impl_kfunc(desc->func_id)) { struct bpf_insn ld_addrs[2] = { BPF_LD_IMM64(BPF_REG_4, (long)env->prog->aux) }; insn_buf[0] = ld_addrs[0]; insn_buf[1] = ld_addrs[1]; insn_buf[2] = *insn; *cnt = 3; } return 0; } /* The function requires that first instruction in 'patch' is insnsi[prog->len - 1] */ static int add_hidden_subprog(struct bpf_verifier_env *env, struct bpf_insn *patch, int len) { struct bpf_subprog_info *info = env->subprog_info; int cnt = env->subprog_cnt; struct bpf_prog *prog; /* We only reserve one slot for hidden subprogs in subprog_info. */ if (env->hidden_subprog_cnt) { verbose(env, "verifier internal error: only one hidden subprog supported\n"); return -EFAULT; } /* We're not patching any existing instruction, just appending the new * ones for the hidden subprog. Hence all of the adjustment operations * in bpf_patch_insn_data are no-ops. */ prog = bpf_patch_insn_data(env, env->prog->len - 1, patch, len); if (!prog) return -ENOMEM; env->prog = prog; info[cnt + 1].start = info[cnt].start; info[cnt].start = prog->len - len + 1; env->subprog_cnt++; env->hidden_subprog_cnt++; return 0; } /* Do various post-verification rewrites in a single program pass. * These rewrites simplify JIT and interpreter implementations. */ static int do_misc_fixups(struct bpf_verifier_env *env) { struct bpf_prog *prog = env->prog; enum bpf_attach_type eatype = prog->expected_attach_type; enum bpf_prog_type prog_type = resolve_prog_type(prog); struct bpf_insn *insn = prog->insnsi; const struct bpf_func_proto *fn; const int insn_cnt = prog->len; const struct bpf_map_ops *ops; struct bpf_insn_aux_data *aux; struct bpf_insn *insn_buf = env->insn_buf; struct bpf_prog *new_prog; struct bpf_map *map_ptr; int i, ret, cnt, delta = 0, cur_subprog = 0; struct bpf_subprog_info *subprogs = env->subprog_info; u16 stack_depth = subprogs[cur_subprog].stack_depth; u16 stack_depth_extra = 0; if (env->seen_exception && !env->exception_callback_subprog) { struct bpf_insn patch[] = { env->prog->insnsi[insn_cnt - 1], BPF_MOV64_REG(BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }; ret = add_hidden_subprog(env, patch, ARRAY_SIZE(patch)); if (ret < 0) return ret; prog = env->prog; insn = prog->insnsi; env->exception_callback_subprog = env->subprog_cnt - 1; /* Don't update insn_cnt, as add_hidden_subprog always appends insns */ mark_subprog_exc_cb(env, env->exception_callback_subprog); } for (i = 0; i < insn_cnt;) { if (insn->code == (BPF_ALU64 | BPF_MOV | BPF_X) && insn->imm) { if ((insn->off == BPF_ADDR_SPACE_CAST && insn->imm == 1) || (((struct bpf_map *)env->prog->aux->arena)->map_flags & BPF_F_NO_USER_CONV)) { /* convert to 32-bit mov that clears upper 32-bit */ insn->code = BPF_ALU | BPF_MOV | BPF_X; /* clear off and imm, so it's a normal 'wX = wY' from JIT pov */ insn->off = 0; insn->imm = 0; } /* cast from as(0) to as(1) should be handled by JIT */ goto next_insn; } if (env->insn_aux_data[i + delta].needs_zext) /* Convert BPF_CLASS(insn->code) == BPF_ALU64 to 32-bit ALU */ insn->code = BPF_ALU | BPF_OP(insn->code) | BPF_SRC(insn->code); /* Make sdiv/smod divide-by-minus-one exceptions impossible. */ if ((insn->code == (BPF_ALU64 | BPF_MOD | BPF_K) || insn->code == (BPF_ALU64 | BPF_DIV | BPF_K) || insn->code == (BPF_ALU | BPF_MOD | BPF_K) || insn->code == (BPF_ALU | BPF_DIV | BPF_K)) && insn->off == 1 && insn->imm == -1) { bool is64 = BPF_CLASS(insn->code) == BPF_ALU64; bool isdiv = BPF_OP(insn->code) == BPF_DIV; struct bpf_insn *patchlet; struct bpf_insn chk_and_sdiv[] = { BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) | BPF_NEG | BPF_K, insn->dst_reg, 0, 0, 0), }; struct bpf_insn chk_and_smod[] = { BPF_MOV32_IMM(insn->dst_reg, 0), }; patchlet = isdiv ? chk_and_sdiv : chk_and_smod; cnt = isdiv ? ARRAY_SIZE(chk_and_sdiv) : ARRAY_SIZE(chk_and_smod); new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } /* Make divide-by-zero and divide-by-minus-one exceptions impossible. */ if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) || insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) || insn->code == (BPF_ALU | BPF_MOD | BPF_X) || insn->code == (BPF_ALU | BPF_DIV | BPF_X)) { bool is64 = BPF_CLASS(insn->code) == BPF_ALU64; bool isdiv = BPF_OP(insn->code) == BPF_DIV; bool is_sdiv = isdiv && insn->off == 1; bool is_smod = !isdiv && insn->off == 1; struct bpf_insn *patchlet; struct bpf_insn chk_and_div[] = { /* [R,W]x div 0 -> 0 */ BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | BPF_JNE | BPF_K, insn->src_reg, 0, 2, 0), BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg), BPF_JMP_IMM(BPF_JA, 0, 0, 1), *insn, }; struct bpf_insn chk_and_mod[] = { /* [R,W]x mod 0 -> [R,W]x */ BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | BPF_JEQ | BPF_K, insn->src_reg, 0, 1 + (is64 ? 0 : 1), 0), *insn, BPF_JMP_IMM(BPF_JA, 0, 0, 1), BPF_MOV32_REG(insn->dst_reg, insn->dst_reg), }; struct bpf_insn chk_and_sdiv[] = { /* [R,W]x sdiv 0 -> 0 * LLONG_MIN sdiv -1 -> LLONG_MIN * INT_MIN sdiv -1 -> INT_MIN */ BPF_MOV64_REG(BPF_REG_AX, insn->src_reg), BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) | BPF_ADD | BPF_K, BPF_REG_AX, 0, 0, 1), BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | BPF_JGT | BPF_K, BPF_REG_AX, 0, 4, 1), BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | BPF_JEQ | BPF_K, BPF_REG_AX, 0, 1, 0), BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) | BPF_MOV | BPF_K, insn->dst_reg, 0, 0, 0), /* BPF_NEG(LLONG_MIN) == -LLONG_MIN == LLONG_MIN */ BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) | BPF_NEG | BPF_K, insn->dst_reg, 0, 0, 0), BPF_JMP_IMM(BPF_JA, 0, 0, 1), *insn, }; struct bpf_insn chk_and_smod[] = { /* [R,W]x mod 0 -> [R,W]x */ /* [R,W]x mod -1 -> 0 */ BPF_MOV64_REG(BPF_REG_AX, insn->src_reg), BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) | BPF_ADD | BPF_K, BPF_REG_AX, 0, 0, 1), BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | BPF_JGT | BPF_K, BPF_REG_AX, 0, 3, 1), BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | BPF_JEQ | BPF_K, BPF_REG_AX, 0, 3 + (is64 ? 0 : 1), 1), BPF_MOV32_IMM(insn->dst_reg, 0), BPF_JMP_IMM(BPF_JA, 0, 0, 1), *insn, BPF_JMP_IMM(BPF_JA, 0, 0, 1), BPF_MOV32_REG(insn->dst_reg, insn->dst_reg), }; if (is_sdiv) { patchlet = chk_and_sdiv; cnt = ARRAY_SIZE(chk_and_sdiv); } else if (is_smod) { patchlet = chk_and_smod; cnt = ARRAY_SIZE(chk_and_smod) - (is64 ? 2 : 0); } else { patchlet = isdiv ? chk_and_div : chk_and_mod; cnt = isdiv ? ARRAY_SIZE(chk_and_div) : ARRAY_SIZE(chk_and_mod) - (is64 ? 2 : 0); } new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } /* Make it impossible to de-reference a userspace address */ if (BPF_CLASS(insn->code) == BPF_LDX && (BPF_MODE(insn->code) == BPF_PROBE_MEM || BPF_MODE(insn->code) == BPF_PROBE_MEMSX)) { struct bpf_insn *patch = &insn_buf[0]; u64 uaddress_limit = bpf_arch_uaddress_limit(); if (!uaddress_limit) goto next_insn; *patch++ = BPF_MOV64_REG(BPF_REG_AX, insn->src_reg); if (insn->off) *patch++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_AX, insn->off); *patch++ = BPF_ALU64_IMM(BPF_RSH, BPF_REG_AX, 32); *patch++ = BPF_JMP_IMM(BPF_JLE, BPF_REG_AX, uaddress_limit >> 32, 2); *patch++ = *insn; *patch++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1); *patch++ = BPF_MOV64_IMM(insn->dst_reg, 0); cnt = patch - insn_buf; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } /* Implement LD_ABS and LD_IND with a rewrite, if supported by the program type. */ if (BPF_CLASS(insn->code) == BPF_LD && (BPF_MODE(insn->code) == BPF_ABS || BPF_MODE(insn->code) == BPF_IND)) { cnt = env->ops->gen_ld_abs(insn, insn_buf); if (cnt == 0 || cnt >= INSN_BUF_SIZE) { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; } new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } /* Rewrite pointer arithmetic to mitigate speculation attacks. */ if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) || insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) { const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X; const u8 code_sub = BPF_ALU64 | BPF_SUB | BPF_X; struct bpf_insn *patch = &insn_buf[0]; bool issrc, isneg, isimm; u32 off_reg; aux = &env->insn_aux_data[i + delta]; if (!aux->alu_state || aux->alu_state == BPF_ALU_NON_POINTER) goto next_insn; isneg = aux->alu_state & BPF_ALU_NEG_VALUE; issrc = (aux->alu_state & BPF_ALU_SANITIZE) == BPF_ALU_SANITIZE_SRC; isimm = aux->alu_state & BPF_ALU_IMMEDIATE; off_reg = issrc ? insn->src_reg : insn->dst_reg; if (isimm) { *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit); } else { if (isneg) *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1); *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit); *patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg); *patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg); *patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0); *patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, 63); *patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, off_reg); } if (!issrc) *patch++ = BPF_MOV64_REG(insn->dst_reg, insn->src_reg); insn->src_reg = BPF_REG_AX; if (isneg) insn->code = insn->code == code_add ? code_sub : code_add; *patch++ = *insn; if (issrc && isneg && !isimm) *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1); cnt = patch - insn_buf; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } if (is_may_goto_insn(insn)) { int stack_off = -stack_depth - 8; stack_depth_extra = 8; insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_AX, BPF_REG_10, stack_off); if (insn->off >= 0) insn_buf[1] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_AX, 0, insn->off + 2); else insn_buf[1] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_AX, 0, insn->off - 1); insn_buf[2] = BPF_ALU64_IMM(BPF_SUB, BPF_REG_AX, 1); insn_buf[3] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_AX, stack_off); cnt = 4; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } if (insn->code != (BPF_JMP | BPF_CALL)) goto next_insn; if (insn->src_reg == BPF_PSEUDO_CALL) goto next_insn; if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { ret = fixup_kfunc_call(env, insn, insn_buf, i + delta, &cnt); if (ret) return ret; if (cnt == 0) goto next_insn; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } /* Skip inlining the helper call if the JIT does it. */ if (bpf_jit_inlines_helper_call(insn->imm)) goto next_insn; if (insn->imm == BPF_FUNC_get_route_realm) prog->dst_needed = 1; if (insn->imm == BPF_FUNC_get_prandom_u32) bpf_user_rnd_init_once(); if (insn->imm == BPF_FUNC_override_return) prog->kprobe_override = 1; if (insn->imm == BPF_FUNC_tail_call) { /* If we tail call into other programs, we * cannot make any assumptions since they can * be replaced dynamically during runtime in * the program array. */ prog->cb_access = 1; if (!allow_tail_call_in_subprogs(env)) prog->aux->stack_depth = MAX_BPF_STACK; prog->aux->max_pkt_offset = MAX_PACKET_OFF; /* mark bpf_tail_call as different opcode to avoid * conditional branch in the interpreter for every normal * call and to prevent accidental JITing by JIT compiler * that doesn't support bpf_tail_call yet */ insn->imm = 0; insn->code = BPF_JMP | BPF_TAIL_CALL; aux = &env->insn_aux_data[i + delta]; if (env->bpf_capable && !prog->blinding_requested && prog->jit_requested && !bpf_map_key_poisoned(aux) && !bpf_map_ptr_poisoned(aux) && !bpf_map_ptr_unpriv(aux)) { struct bpf_jit_poke_descriptor desc = { .reason = BPF_POKE_REASON_TAIL_CALL, .tail_call.map = aux->map_ptr_state.map_ptr, .tail_call.key = bpf_map_key_immediate(aux), .insn_idx = i + delta, }; ret = bpf_jit_add_poke_descriptor(prog, &desc); if (ret < 0) { verbose(env, "adding tail call poke descriptor failed\n"); return ret; } insn->imm = ret + 1; goto next_insn; } if (!bpf_map_ptr_unpriv(aux)) goto next_insn; /* instead of changing every JIT dealing with tail_call * emit two extra insns: * if (index >= max_entries) goto out; * index &= array->index_mask; * to avoid out-of-bounds cpu speculation */ if (bpf_map_ptr_poisoned(aux)) { verbose(env, "tail_call abusing map_ptr\n"); return -EINVAL; } map_ptr = aux->map_ptr_state.map_ptr; insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3, map_ptr->max_entries, 2); insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3, container_of(map_ptr, struct bpf_array, map)->index_mask); insn_buf[2] = *insn; cnt = 3; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } if (insn->imm == BPF_FUNC_timer_set_callback) { /* The verifier will process callback_fn as many times as necessary * with different maps and the register states prepared by * set_timer_callback_state will be accurate. * * The following use case is valid: * map1 is shared by prog1, prog2, prog3. * prog1 calls bpf_timer_init for some map1 elements * prog2 calls bpf_timer_set_callback for some map1 elements. * Those that were not bpf_timer_init-ed will return -EINVAL. * prog3 calls bpf_timer_start for some map1 elements. * Those that were not both bpf_timer_init-ed and * bpf_timer_set_callback-ed will return -EINVAL. */ struct bpf_insn ld_addrs[2] = { BPF_LD_IMM64(BPF_REG_3, (long)prog->aux), }; insn_buf[0] = ld_addrs[0]; insn_buf[1] = ld_addrs[1]; insn_buf[2] = *insn; cnt = 3; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto patch_call_imm; } if (is_storage_get_function(insn->imm)) { if (!in_sleepable(env) || env->insn_aux_data[i + delta].storage_get_func_atomic) insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_ATOMIC); else insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_KERNEL); insn_buf[1] = *insn; cnt = 2; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto patch_call_imm; } /* bpf_per_cpu_ptr() and bpf_this_cpu_ptr() */ if (env->insn_aux_data[i + delta].call_with_percpu_alloc_ptr) { /* patch with 'r1 = *(u64 *)(r1 + 0)' since for percpu data, * bpf_mem_alloc() returns a ptr to the percpu data ptr. */ insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 0); insn_buf[1] = *insn; cnt = 2; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto patch_call_imm; } /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup * and other inlining handlers are currently limited to 64 bit * only. */ if (prog->jit_requested && BITS_PER_LONG == 64 && (insn->imm == BPF_FUNC_map_lookup_elem || insn->imm == BPF_FUNC_map_update_elem || insn->imm == BPF_FUNC_map_delete_elem || insn->imm == BPF_FUNC_map_push_elem || insn->imm == BPF_FUNC_map_pop_elem || insn->imm == BPF_FUNC_map_peek_elem || insn->imm == BPF_FUNC_redirect_map || insn->imm == BPF_FUNC_for_each_map_elem || insn->imm == BPF_FUNC_map_lookup_percpu_elem)) { aux = &env->insn_aux_data[i + delta]; if (bpf_map_ptr_poisoned(aux)) goto patch_call_imm; map_ptr = aux->map_ptr_state.map_ptr; ops = map_ptr->ops; if (insn->imm == BPF_FUNC_map_lookup_elem && ops->map_gen_lookup) { cnt = ops->map_gen_lookup(map_ptr, insn_buf); if (cnt == -EOPNOTSUPP) goto patch_map_ops_generic; if (cnt <= 0 || cnt >= INSN_BUF_SIZE) { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; } new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } BUILD_BUG_ON(!__same_type(ops->map_lookup_elem, (void *(*)(struct bpf_map *map, void *key))NULL)); BUILD_BUG_ON(!__same_type(ops->map_delete_elem, (long (*)(struct bpf_map *map, void *key))NULL)); BUILD_BUG_ON(!__same_type(ops->map_update_elem, (long (*)(struct bpf_map *map, void *key, void *value, u64 flags))NULL)); BUILD_BUG_ON(!__same_type(ops->map_push_elem, (long (*)(struct bpf_map *map, void *value, u64 flags))NULL)); BUILD_BUG_ON(!__same_type(ops->map_pop_elem, (long (*)(struct bpf_map *map, void *value))NULL)); BUILD_BUG_ON(!__same_type(ops->map_peek_elem, (long (*)(struct bpf_map *map, void *value))NULL)); BUILD_BUG_ON(!__same_type(ops->map_redirect, (long (*)(struct bpf_map *map, u64 index, u64 flags))NULL)); BUILD_BUG_ON(!__same_type(ops->map_for_each_callback, (long (*)(struct bpf_map *map, bpf_callback_t callback_fn, void *callback_ctx, u64 flags))NULL)); BUILD_BUG_ON(!__same_type(ops->map_lookup_percpu_elem, (void *(*)(struct bpf_map *map, void *key, u32 cpu))NULL)); patch_map_ops_generic: switch (insn->imm) { case BPF_FUNC_map_lookup_elem: insn->imm = BPF_CALL_IMM(ops->map_lookup_elem); goto next_insn; case BPF_FUNC_map_update_elem: insn->imm = BPF_CALL_IMM(ops->map_update_elem); goto next_insn; case BPF_FUNC_map_delete_elem: insn->imm = BPF_CALL_IMM(ops->map_delete_elem); goto next_insn; case BPF_FUNC_map_push_elem: insn->imm = BPF_CALL_IMM(ops->map_push_elem); goto next_insn; case BPF_FUNC_map_pop_elem: insn->imm = BPF_CALL_IMM(ops->map_pop_elem); goto next_insn; case BPF_FUNC_map_peek_elem: insn->imm = BPF_CALL_IMM(ops->map_peek_elem); goto next_insn; case BPF_FUNC_redirect_map: insn->imm = BPF_CALL_IMM(ops->map_redirect); goto next_insn; case BPF_FUNC_for_each_map_elem: insn->imm = BPF_CALL_IMM(ops->map_for_each_callback); goto next_insn; case BPF_FUNC_map_lookup_percpu_elem: insn->imm = BPF_CALL_IMM(ops->map_lookup_percpu_elem); goto next_insn; } goto patch_call_imm; } /* Implement bpf_jiffies64 inline. */ if (prog->jit_requested && BITS_PER_LONG == 64 && insn->imm == BPF_FUNC_jiffies64) { struct bpf_insn ld_jiffies_addr[2] = { BPF_LD_IMM64(BPF_REG_0, (unsigned long)&jiffies), }; insn_buf[0] = ld_jiffies_addr[0]; insn_buf[1] = ld_jiffies_addr[1]; insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0); cnt = 3; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } #if defined(CONFIG_X86_64) && !defined(CONFIG_UML) /* Implement bpf_get_smp_processor_id() inline. */ if (insn->imm == BPF_FUNC_get_smp_processor_id && verifier_inlines_helper_call(env, insn->imm)) { /* BPF_FUNC_get_smp_processor_id inlining is an * optimization, so if pcpu_hot.cpu_number is ever * changed in some incompatible and hard to support * way, it's fine to back out this inlining logic */ #ifdef CONFIG_SMP insn_buf[0] = BPF_MOV32_IMM(BPF_REG_0, (u32)(unsigned long)&pcpu_hot.cpu_number); insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0); insn_buf[2] = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0); cnt = 3; #else insn_buf[0] = BPF_ALU32_REG(BPF_XOR, BPF_REG_0, BPF_REG_0); cnt = 1; #endif new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } #endif /* Implement bpf_get_func_arg inline. */ if (prog_type == BPF_PROG_TYPE_TRACING && insn->imm == BPF_FUNC_get_func_arg) { /* Load nr_args from ctx - 8 */ insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); insn_buf[1] = BPF_JMP32_REG(BPF_JGE, BPF_REG_2, BPF_REG_0, 6); insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_2, 3); insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_1); insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_2, 0); insn_buf[5] = BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0); insn_buf[6] = BPF_MOV64_IMM(BPF_REG_0, 0); insn_buf[7] = BPF_JMP_A(1); insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL); cnt = 9; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } /* Implement bpf_get_func_ret inline. */ if (prog_type == BPF_PROG_TYPE_TRACING && insn->imm == BPF_FUNC_get_func_ret) { if (eatype == BPF_TRACE_FEXIT || eatype == BPF_MODIFY_RETURN) { /* Load nr_args from ctx - 8 */ insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); insn_buf[1] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3); insn_buf[2] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1); insn_buf[3] = BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0); insn_buf[4] = BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_3, 0); insn_buf[5] = BPF_MOV64_IMM(BPF_REG_0, 0); cnt = 6; } else { insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, -EOPNOTSUPP); cnt = 1; } new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } /* Implement get_func_arg_cnt inline. */ if (prog_type == BPF_PROG_TYPE_TRACING && insn->imm == BPF_FUNC_get_func_arg_cnt) { /* Load nr_args from ctx - 8 */ insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1); if (!new_prog) return -ENOMEM; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } /* Implement bpf_get_func_ip inline. */ if (prog_type == BPF_PROG_TYPE_TRACING && insn->imm == BPF_FUNC_get_func_ip) { /* Load IP address from ctx - 16 */ insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -16); new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1); if (!new_prog) return -ENOMEM; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } /* Implement bpf_get_branch_snapshot inline. */ if (IS_ENABLED(CONFIG_PERF_EVENTS) && prog->jit_requested && BITS_PER_LONG == 64 && insn->imm == BPF_FUNC_get_branch_snapshot) { /* We are dealing with the following func protos: * u64 bpf_get_branch_snapshot(void *buf, u32 size, u64 flags); * int perf_snapshot_branch_stack(struct perf_branch_entry *entries, u32 cnt); */ const u32 br_entry_size = sizeof(struct perf_branch_entry); /* struct perf_branch_entry is part of UAPI and is * used as an array element, so extremely unlikely to * ever grow or shrink */ BUILD_BUG_ON(br_entry_size != 24); /* if (unlikely(flags)) return -EINVAL */ insn_buf[0] = BPF_JMP_IMM(BPF_JNE, BPF_REG_3, 0, 7); /* Transform size (bytes) into number of entries (cnt = size / 24). * But to avoid expensive division instruction, we implement * divide-by-3 through multiplication, followed by further * division by 8 through 3-bit right shift. * Refer to book "Hacker's Delight, 2nd ed." by Henry S. Warren, Jr., * p. 227, chapter "Unsigned Division by 3" for details and proofs. * * N / 3 <=> M * N / 2^33, where M = (2^33 + 1) / 3 = 0xaaaaaaab. */ insn_buf[1] = BPF_MOV32_IMM(BPF_REG_0, 0xaaaaaaab); insn_buf[2] = BPF_ALU64_REG(BPF_MUL, BPF_REG_2, BPF_REG_0); insn_buf[3] = BPF_ALU64_IMM(BPF_RSH, BPF_REG_2, 36); /* call perf_snapshot_branch_stack implementation */ insn_buf[4] = BPF_EMIT_CALL(static_call_query(perf_snapshot_branch_stack)); /* if (entry_cnt == 0) return -ENOENT */ insn_buf[5] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4); /* return entry_cnt * sizeof(struct perf_branch_entry) */ insn_buf[6] = BPF_ALU32_IMM(BPF_MUL, BPF_REG_0, br_entry_size); insn_buf[7] = BPF_JMP_A(3); /* return -EINVAL; */ insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL); insn_buf[9] = BPF_JMP_A(1); /* return -ENOENT; */ insn_buf[10] = BPF_MOV64_IMM(BPF_REG_0, -ENOENT); cnt = 11; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } /* Implement bpf_kptr_xchg inline */ if (prog->jit_requested && BITS_PER_LONG == 64 && insn->imm == BPF_FUNC_kptr_xchg && bpf_jit_supports_ptr_xchg()) { insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_2); insn_buf[1] = BPF_ATOMIC_OP(BPF_DW, BPF_XCHG, BPF_REG_1, BPF_REG_0, 0); cnt = 2; new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = prog = new_prog; insn = new_prog->insnsi + i + delta; goto next_insn; } patch_call_imm: fn = env->ops->get_func_proto(insn->imm, env->prog); /* all functions that have prototype and verifier allowed * programs to call them, must be real in-kernel functions */ if (!fn->func) { verbose(env, "kernel subsystem misconfigured func %s#%d\n", func_id_name(insn->imm), insn->imm); return -EFAULT; } insn->imm = fn->func - __bpf_call_base; next_insn: if (subprogs[cur_subprog + 1].start == i + delta + 1) { subprogs[cur_subprog].stack_depth += stack_depth_extra; subprogs[cur_subprog].stack_extra = stack_depth_extra; cur_subprog++; stack_depth = subprogs[cur_subprog].stack_depth; stack_depth_extra = 0; } i++; insn++; } env->prog->aux->stack_depth = subprogs[0].stack_depth; for (i = 0; i < env->subprog_cnt; i++) { int subprog_start = subprogs[i].start; int stack_slots = subprogs[i].stack_extra / 8; if (!stack_slots) continue; if (stack_slots > 1) { verbose(env, "verifier bug: stack_slots supports may_goto only\n"); return -EFAULT; } /* Add ST insn to subprog prologue to init extra stack */ insn_buf[0] = BPF_ST_MEM(BPF_DW, BPF_REG_FP, -subprogs[i].stack_depth, BPF_MAX_LOOPS); /* Copy first actual insn to preserve it */ insn_buf[1] = env->prog->insnsi[subprog_start]; new_prog = bpf_patch_insn_data(env, subprog_start, insn_buf, 2); if (!new_prog) return -ENOMEM; env->prog = prog = new_prog; /* * If may_goto is a first insn of a prog there could be a jmp * insn that points to it, hence adjust all such jmps to point * to insn after BPF_ST that inits may_goto count. * Adjustment will succeed because bpf_patch_insn_data() didn't fail. */ WARN_ON(adjust_jmp_off(env->prog, subprog_start, 1)); } /* Since poke tab is now finalized, publish aux to tracker. */ for (i = 0; i < prog->aux->size_poke_tab; i++) { map_ptr = prog->aux->poke_tab[i].tail_call.map; if (!map_ptr->ops->map_poke_track || !map_ptr->ops->map_poke_untrack || !map_ptr->ops->map_poke_run) { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; } ret = map_ptr->ops->map_poke_track(map_ptr, prog->aux); if (ret < 0) { verbose(env, "tracking tail call prog failed\n"); return ret; } } sort_kfunc_descs_by_imm_off(env->prog); return 0; } static struct bpf_prog *inline_bpf_loop(struct bpf_verifier_env *env, int position, s32 stack_base, u32 callback_subprogno, u32 *total_cnt) { s32 r6_offset = stack_base + 0 * BPF_REG_SIZE; s32 r7_offset = stack_base + 1 * BPF_REG_SIZE; s32 r8_offset = stack_base + 2 * BPF_REG_SIZE; int reg_loop_max = BPF_REG_6; int reg_loop_cnt = BPF_REG_7; int reg_loop_ctx = BPF_REG_8; struct bpf_insn *insn_buf = env->insn_buf; struct bpf_prog *new_prog; u32 callback_start; u32 call_insn_offset; s32 callback_offset; u32 cnt = 0; /* This represents an inlined version of bpf_iter.c:bpf_loop, * be careful to modify this code in sync. */ /* Return error and jump to the end of the patch if * expected number of iterations is too big. */ insn_buf[cnt++] = BPF_JMP_IMM(BPF_JLE, BPF_REG_1, BPF_MAX_LOOPS, 2); insn_buf[cnt++] = BPF_MOV32_IMM(BPF_REG_0, -E2BIG); insn_buf[cnt++] = BPF_JMP_IMM(BPF_JA, 0, 0, 16); /* spill R6, R7, R8 to use these as loop vars */ insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, r6_offset); insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_7, r7_offset); insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_8, r8_offset); /* initialize loop vars */ insn_buf[cnt++] = BPF_MOV64_REG(reg_loop_max, BPF_REG_1); insn_buf[cnt++] = BPF_MOV32_IMM(reg_loop_cnt, 0); insn_buf[cnt++] = BPF_MOV64_REG(reg_loop_ctx, BPF_REG_3); /* loop header, * if reg_loop_cnt >= reg_loop_max skip the loop body */ insn_buf[cnt++] = BPF_JMP_REG(BPF_JGE, reg_loop_cnt, reg_loop_max, 5); /* callback call, * correct callback offset would be set after patching */ insn_buf[cnt++] = BPF_MOV64_REG(BPF_REG_1, reg_loop_cnt); insn_buf[cnt++] = BPF_MOV64_REG(BPF_REG_2, reg_loop_ctx); insn_buf[cnt++] = BPF_CALL_REL(0); /* increment loop counter */ insn_buf[cnt++] = BPF_ALU64_IMM(BPF_ADD, reg_loop_cnt, 1); /* jump to loop header if callback returned 0 */ insn_buf[cnt++] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, -6); /* return value of bpf_loop, * set R0 to the number of iterations */ insn_buf[cnt++] = BPF_MOV64_REG(BPF_REG_0, reg_loop_cnt); /* restore original values of R6, R7, R8 */ insn_buf[cnt++] = BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_10, r6_offset); insn_buf[cnt++] = BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, r7_offset); insn_buf[cnt++] = BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_10, r8_offset); *total_cnt = cnt; new_prog = bpf_patch_insn_data(env, position, insn_buf, cnt); if (!new_prog) return new_prog; /* callback start is known only after patching */ callback_start = env->subprog_info[callback_subprogno].start; /* Note: insn_buf[12] is an offset of BPF_CALL_REL instruction */ call_insn_offset = position + 12; callback_offset = callback_start - call_insn_offset - 1; new_prog->insnsi[call_insn_offset].imm = callback_offset; return new_prog; } static bool is_bpf_loop_call(struct bpf_insn *insn) { return insn->code == (BPF_JMP | BPF_CALL) && insn->src_reg == 0 && insn->imm == BPF_FUNC_loop; } /* For all sub-programs in the program (including main) check * insn_aux_data to see if there are bpf_loop calls that require * inlining. If such calls are found the calls are replaced with a * sequence of instructions produced by `inline_bpf_loop` function and * subprog stack_depth is increased by the size of 3 registers. * This stack space is used to spill values of the R6, R7, R8. These * registers are used to store the loop bound, counter and context * variables. */ static int optimize_bpf_loop(struct bpf_verifier_env *env) { struct bpf_subprog_info *subprogs = env->subprog_info; int i, cur_subprog = 0, cnt, delta = 0; struct bpf_insn *insn = env->prog->insnsi; int insn_cnt = env->prog->len; u16 stack_depth = subprogs[cur_subprog].stack_depth; u16 stack_depth_roundup = round_up(stack_depth, 8) - stack_depth; u16 stack_depth_extra = 0; for (i = 0; i < insn_cnt; i++, insn++) { struct bpf_loop_inline_state *inline_state = &env->insn_aux_data[i + delta].loop_inline_state; if (is_bpf_loop_call(insn) && inline_state->fit_for_inline) { struct bpf_prog *new_prog; stack_depth_extra = BPF_REG_SIZE * 3 + stack_depth_roundup; new_prog = inline_bpf_loop(env, i + delta, -(stack_depth + stack_depth_extra), inline_state->callback_subprogno, &cnt); if (!new_prog) return -ENOMEM; delta += cnt - 1; env->prog = new_prog; insn = new_prog->insnsi + i + delta; } if (subprogs[cur_subprog + 1].start == i + delta + 1) { subprogs[cur_subprog].stack_depth += stack_depth_extra; cur_subprog++; stack_depth = subprogs[cur_subprog].stack_depth; stack_depth_roundup = round_up(stack_depth, 8) - stack_depth; stack_depth_extra = 0; } } env->prog->aux->stack_depth = env->subprog_info[0].stack_depth; return 0; } /* Remove unnecessary spill/fill pairs, members of fastcall pattern, * adjust subprograms stack depth when possible. */ static int remove_fastcall_spills_fills(struct bpf_verifier_env *env) { struct bpf_subprog_info *subprog = env->subprog_info; struct bpf_insn_aux_data *aux = env->insn_aux_data; struct bpf_insn *insn = env->prog->insnsi; int insn_cnt = env->prog->len; u32 spills_num; bool modified = false; int i, j; for (i = 0; i < insn_cnt; i++, insn++) { if (aux[i].fastcall_spills_num > 0) { spills_num = aux[i].fastcall_spills_num; /* NOPs would be removed by opt_remove_nops() */ for (j = 1; j <= spills_num; ++j) { *(insn - j) = NOP; *(insn + j) = NOP; } modified = true; } if ((subprog + 1)->start == i + 1) { if (modified && !subprog->keep_fastcall_stack) subprog->stack_depth = -subprog->fastcall_stack_off; subprog++; modified = false; } } return 0; } static void free_states(struct bpf_verifier_env *env) { struct bpf_verifier_state_list *sl, *sln; int i; sl = env->free_list; while (sl) { sln = sl->next; free_verifier_state(&sl->state, false); kfree(sl); sl = sln; } env->free_list = NULL; if (!env->explored_states) return; for (i = 0; i < state_htab_size(env); i++) { sl = env->explored_states[i]; while (sl) { sln = sl->next; free_verifier_state(&sl->state, false); kfree(sl); sl = sln; } env->explored_states[i] = NULL; } } static int do_check_common(struct bpf_verifier_env *env, int subprog) { bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); struct bpf_subprog_info *sub = subprog_info(env, subprog); struct bpf_verifier_state *state; struct bpf_reg_state *regs; int ret, i; env->prev_linfo = NULL; env->pass_cnt++; state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL); if (!state) return -ENOMEM; state->curframe = 0; state->speculative = false; state->branches = 1; state->frame[0] = kzalloc(sizeof(struct bpf_func_state), GFP_KERNEL); if (!state->frame[0]) { kfree(state); return -ENOMEM; } env->cur_state = state; init_func_state(env, state->frame[0], BPF_MAIN_FUNC /* callsite */, 0 /* frameno */, subprog); state->first_insn_idx = env->subprog_info[subprog].start; state->last_insn_idx = -1; regs = state->frame[state->curframe]->regs; if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) { const char *sub_name = subprog_name(env, subprog); struct bpf_subprog_arg_info *arg; struct bpf_reg_state *reg; verbose(env, "Validating %s() func#%d...\n", sub_name, subprog); ret = btf_prepare_func_args(env, subprog); if (ret) goto out; if (subprog_is_exc_cb(env, subprog)) { state->frame[0]->in_exception_callback_fn = true; /* We have already ensured that the callback returns an integer, just * like all global subprogs. We need to determine it only has a single * scalar argument. */ if (sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_ANYTHING) { verbose(env, "exception cb only supports single integer argument\n"); ret = -EINVAL; goto out; } } for (i = BPF_REG_1; i <= sub->arg_cnt; i++) { arg = &sub->args[i - BPF_REG_1]; reg = ®s[i]; if (arg->arg_type == ARG_PTR_TO_CTX) { reg->type = PTR_TO_CTX; mark_reg_known_zero(env, regs, i); } else if (arg->arg_type == ARG_ANYTHING) { reg->type = SCALAR_VALUE; mark_reg_unknown(env, regs, i); } else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) { /* assume unspecial LOCAL dynptr type */ __mark_dynptr_reg(reg, BPF_DYNPTR_TYPE_LOCAL, true, ++env->id_gen); } else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) { reg->type = PTR_TO_MEM; if (arg->arg_type & PTR_MAYBE_NULL) reg->type |= PTR_MAYBE_NULL; mark_reg_known_zero(env, regs, i); reg->mem_size = arg->mem_size; reg->id = ++env->id_gen; } else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) { reg->type = PTR_TO_BTF_ID; if (arg->arg_type & PTR_MAYBE_NULL) reg->type |= PTR_MAYBE_NULL; if (arg->arg_type & PTR_UNTRUSTED) reg->type |= PTR_UNTRUSTED; if (arg->arg_type & PTR_TRUSTED) reg->type |= PTR_TRUSTED; mark_reg_known_zero(env, regs, i); reg->btf = bpf_get_btf_vmlinux(); /* can't fail at this point */ reg->btf_id = arg->btf_id; reg->id = ++env->id_gen; } else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) { /* caller can pass either PTR_TO_ARENA or SCALAR */ mark_reg_unknown(env, regs, i); } else { WARN_ONCE(1, "BUG: unhandled arg#%d type %d\n", i - BPF_REG_1, arg->arg_type); ret = -EFAULT; goto out; } } } else { /* if main BPF program has associated BTF info, validate that * it's matching expected signature, and otherwise mark BTF * info for main program as unreliable */ if (env->prog->aux->func_info_aux) { ret = btf_prepare_func_args(env, 0); if (ret || sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_PTR_TO_CTX) env->prog->aux->func_info_aux[0].unreliable = true; } /* 1st arg to a function */ regs[BPF_REG_1].type = PTR_TO_CTX; mark_reg_known_zero(env, regs, BPF_REG_1); } ret = do_check(env); out: /* check for NULL is necessary, since cur_state can be freed inside * do_check() under memory pressure. */ if (env->cur_state) { free_verifier_state(env->cur_state, true); env->cur_state = NULL; } while (!pop_stack(env, NULL, NULL, false)); if (!ret && pop_log) bpf_vlog_reset(&env->log, 0); free_states(env); return ret; } /* Lazily verify all global functions based on their BTF, if they are called * from main BPF program or any of subprograms transitively. * BPF global subprogs called from dead code are not validated. * All callable global functions must pass verification. * Otherwise the whole program is rejected. * Consider: * int bar(int); * int foo(int f) * { * return bar(f); * } * int bar(int b) * { * ... * } * foo() will be verified first for R1=any_scalar_value. During verification it * will be assumed that bar() already verified successfully and call to bar() * from foo() will be checked for type match only. Later bar() will be verified * independently to check that it's safe for R1=any_scalar_value. */ static int do_check_subprogs(struct bpf_verifier_env *env) { struct bpf_prog_aux *aux = env->prog->aux; struct bpf_func_info_aux *sub_aux; int i, ret, new_cnt; if (!aux->func_info) return 0; /* exception callback is presumed to be always called */ if (env->exception_callback_subprog) subprog_aux(env, env->exception_callback_subprog)->called = true; again: new_cnt = 0; for (i = 1; i < env->subprog_cnt; i++) { if (!subprog_is_global(env, i)) continue; sub_aux = subprog_aux(env, i); if (!sub_aux->called || sub_aux->verified) continue; env->insn_idx = env->subprog_info[i].start; WARN_ON_ONCE(env->insn_idx == 0); ret = do_check_common(env, i); if (ret) { return ret; } else if (env->log.level & BPF_LOG_LEVEL) { verbose(env, "Func#%d ('%s') is safe for any args that match its prototype\n", i, subprog_name(env, i)); } /* We verified new global subprog, it might have called some * more global subprogs that we haven't verified yet, so we * need to do another pass over subprogs to verify those. */ sub_aux->verified = true; new_cnt++; } /* We can't loop forever as we verify at least one global subprog on * each pass. */ if (new_cnt) goto again; return 0; } static int do_check_main(struct bpf_verifier_env *env) { int ret; env->insn_idx = 0; ret = do_check_common(env, 0); if (!ret) env->prog->aux->stack_depth = env->subprog_info[0].stack_depth; return ret; } static void print_verification_stats(struct bpf_verifier_env *env) { int i; if (env->log.level & BPF_LOG_STATS) { verbose(env, "verification time %lld usec\n", div_u64(env->verification_time, 1000)); verbose(env, "stack depth "); for (i = 0; i < env->subprog_cnt; i++) { u32 depth = env->subprog_info[i].stack_depth; verbose(env, "%d", depth); if (i + 1 < env->subprog_cnt) verbose(env, "+"); } verbose(env, "\n"); } verbose(env, "processed %d insns (limit %d) max_states_per_insn %d " "total_states %d peak_states %d mark_read %d\n", env->insn_processed, BPF_COMPLEXITY_LIMIT_INSNS, env->max_states_per_insn, env->total_states, env->peak_states, env->longest_mark_read_walk); } static int check_struct_ops_btf_id(struct bpf_verifier_env *env) { const struct btf_type *t, *func_proto; const struct bpf_struct_ops_desc *st_ops_desc; const struct bpf_struct_ops *st_ops; const struct btf_member *member; struct bpf_prog *prog = env->prog; u32 btf_id, member_idx; struct btf *btf; const char *mname; int err; if (!prog->gpl_compatible) { verbose(env, "struct ops programs must have a GPL compatible license\n"); return -EINVAL; } if (!prog->aux->attach_btf_id) return -ENOTSUPP; btf = prog->aux->attach_btf; if (btf_is_module(btf)) { /* Make sure st_ops is valid through the lifetime of env */ env->attach_btf_mod = btf_try_get_module(btf); if (!env->attach_btf_mod) { verbose(env, "struct_ops module %s is not found\n", btf_get_name(btf)); return -ENOTSUPP; } } btf_id = prog->aux->attach_btf_id; st_ops_desc = bpf_struct_ops_find(btf, btf_id); if (!st_ops_desc) { verbose(env, "attach_btf_id %u is not a supported struct\n", btf_id); return -ENOTSUPP; } st_ops = st_ops_desc->st_ops; t = st_ops_desc->type; member_idx = prog->expected_attach_type; if (member_idx >= btf_type_vlen(t)) { verbose(env, "attach to invalid member idx %u of struct %s\n", member_idx, st_ops->name); return -EINVAL; } member = &btf_type_member(t)[member_idx]; mname = btf_name_by_offset(btf, member->name_off); func_proto = btf_type_resolve_func_ptr(btf, member->type, NULL); if (!func_proto) { verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n", mname, member_idx, st_ops->name); return -EINVAL; } err = bpf_struct_ops_supported(st_ops, __btf_member_bit_offset(t, member) / 8); if (err) { verbose(env, "attach to unsupported member %s of struct %s\n", mname, st_ops->name); return err; } if (st_ops->check_member) { err = st_ops->check_member(t, member, prog); if (err) { verbose(env, "attach to unsupported member %s of struct %s\n", mname, st_ops->name); return err; } } if (prog->aux->priv_stack_requested && !bpf_jit_supports_private_stack()) { verbose(env, "Private stack not supported by jit\n"); return -EACCES; } /* btf_ctx_access() used this to provide argument type info */ prog->aux->ctx_arg_info = st_ops_desc->arg_info[member_idx].info; prog->aux->ctx_arg_info_size = st_ops_desc->arg_info[member_idx].cnt; prog->aux->attach_func_proto = func_proto; prog->aux->attach_func_name = mname; env->ops = st_ops->verifier_ops; return 0; } #define SECURITY_PREFIX "security_" static int check_attach_modify_return(unsigned long addr, const char *func_name) { if (within_error_injection_list(addr) || !strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1)) return 0; return -EINVAL; } /* list of non-sleepable functions that are otherwise on * ALLOW_ERROR_INJECTION list */ BTF_SET_START(btf_non_sleepable_error_inject) /* Three functions below can be called from sleepable and non-sleepable context. * Assume non-sleepable from bpf safety point of view. */ BTF_ID(func, __filemap_add_folio) #ifdef CONFIG_FAIL_PAGE_ALLOC BTF_ID(func, should_fail_alloc_page) #endif #ifdef CONFIG_FAILSLAB BTF_ID(func, should_failslab) #endif BTF_SET_END(btf_non_sleepable_error_inject) static int check_non_sleepable_error_inject(u32 btf_id) { return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id); } int bpf_check_attach_target(struct bpf_verifier_log *log, const struct bpf_prog *prog, const struct bpf_prog *tgt_prog, u32 btf_id, struct bpf_attach_target_info *tgt_info) { bool prog_extension = prog->type == BPF_PROG_TYPE_EXT; bool prog_tracing = prog->type == BPF_PROG_TYPE_TRACING; char trace_symbol[KSYM_SYMBOL_LEN]; const char prefix[] = "btf_trace_"; struct bpf_raw_event_map *btp; int ret = 0, subprog = -1, i; const struct btf_type *t; bool conservative = true; const char *tname, *fname; struct btf *btf; long addr = 0; struct module *mod = NULL; if (!btf_id) { bpf_log(log, "Tracing programs must provide btf_id\n"); return -EINVAL; } btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf; if (!btf) { bpf_log(log, "FENTRY/FEXIT program can only be attached to another program annotated with BTF\n"); return -EINVAL; } t = btf_type_by_id(btf, btf_id); if (!t) { bpf_log(log, "attach_btf_id %u is invalid\n", btf_id); return -EINVAL; } tname = btf_name_by_offset(btf, t->name_off); if (!tname) { bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id); return -EINVAL; } if (tgt_prog) { struct bpf_prog_aux *aux = tgt_prog->aux; bool tgt_changes_pkt_data; if (bpf_prog_is_dev_bound(prog->aux) && !bpf_prog_dev_bound_match(prog, tgt_prog)) { bpf_log(log, "Target program bound device mismatch"); return -EINVAL; } for (i = 0; i < aux->func_info_cnt; i++) if (aux->func_info[i].type_id == btf_id) { subprog = i; break; } if (subprog == -1) { bpf_log(log, "Subprog %s doesn't exist\n", tname); return -EINVAL; } if (aux->func && aux->func[subprog]->aux->exception_cb) { bpf_log(log, "%s programs cannot attach to exception callback\n", prog_extension ? "Extension" : "FENTRY/FEXIT"); return -EINVAL; } conservative = aux->func_info_aux[subprog].unreliable; if (prog_extension) { if (conservative) { bpf_log(log, "Cannot replace static functions\n"); return -EINVAL; } if (!prog->jit_requested) { bpf_log(log, "Extension programs should be JITed\n"); return -EINVAL; } tgt_changes_pkt_data = aux->func ? aux->func[subprog]->aux->changes_pkt_data : aux->changes_pkt_data; if (prog->aux->changes_pkt_data && !tgt_changes_pkt_data) { bpf_log(log, "Extension program changes packet data, while original does not\n"); return -EINVAL; } } if (!tgt_prog->jited) { bpf_log(log, "Can attach to only JITed progs\n"); return -EINVAL; } if (prog_tracing) { if (aux->attach_tracing_prog) { /* * Target program is an fentry/fexit which is already attached * to another tracing program. More levels of nesting * attachment are not allowed. */ bpf_log(log, "Cannot nest tracing program attach more than once\n"); return -EINVAL; } } else if (tgt_prog->type == prog->type) { /* * To avoid potential call chain cycles, prevent attaching of a * program extension to another extension. It's ok to attach * fentry/fexit to extension program. */ bpf_log(log, "Cannot recursively attach\n"); return -EINVAL; } if (tgt_prog->type == BPF_PROG_TYPE_TRACING && prog_extension && (tgt_prog->expected_attach_type == BPF_TRACE_FENTRY || tgt_prog->expected_attach_type == BPF_TRACE_FEXIT)) { /* Program extensions can extend all program types * except fentry/fexit. The reason is the following. * The fentry/fexit programs are used for performance * analysis, stats and can be attached to any program * type. When extension program is replacing XDP function * it is necessary to allow performance analysis of all * functions. Both original XDP program and its program * extension. Hence attaching fentry/fexit to * BPF_PROG_TYPE_EXT is allowed. If extending of * fentry/fexit was allowed it would be possible to create * long call chain fentry->extension->fentry->extension * beyond reasonable stack size. Hence extending fentry * is not allowed. */ bpf_log(log, "Cannot extend fentry/fexit\n"); return -EINVAL; } } else { if (prog_extension) { bpf_log(log, "Cannot replace kernel functions\n"); return -EINVAL; } } switch (prog->expected_attach_type) { case BPF_TRACE_RAW_TP: if (tgt_prog) { bpf_log(log, "Only FENTRY/FEXIT progs are attachable to another BPF prog\n"); return -EINVAL; } if (!btf_type_is_typedef(t)) { bpf_log(log, "attach_btf_id %u is not a typedef\n", btf_id); return -EINVAL; } if (strncmp(prefix, tname, sizeof(prefix) - 1)) { bpf_log(log, "attach_btf_id %u points to wrong type name %s\n", btf_id, tname); return -EINVAL; } tname += sizeof(prefix) - 1; /* The func_proto of "btf_trace_##tname" is generated from typedef without argument * names. Thus using bpf_raw_event_map to get argument names. */ btp = bpf_get_raw_tracepoint(tname); if (!btp) return -EINVAL; fname = kallsyms_lookup((unsigned long)btp->bpf_func, NULL, NULL, NULL, trace_symbol); bpf_put_raw_tracepoint(btp); if (fname) ret = btf_find_by_name_kind(btf, fname, BTF_KIND_FUNC); if (!fname || ret < 0) { bpf_log(log, "Cannot find btf of tracepoint template, fall back to %s%s.\n", prefix, tname); t = btf_type_by_id(btf, t->type); if (!btf_type_is_ptr(t)) /* should never happen in valid vmlinux build */ return -EINVAL; } else { t = btf_type_by_id(btf, ret); if (!btf_type_is_func(t)) /* should never happen in valid vmlinux build */ return -EINVAL; } t = btf_type_by_id(btf, t->type); if (!btf_type_is_func_proto(t)) /* should never happen in valid vmlinux build */ return -EINVAL; break; case BPF_TRACE_ITER: if (!btf_type_is_func(t)) { bpf_log(log, "attach_btf_id %u is not a function\n", btf_id); return -EINVAL; } t = btf_type_by_id(btf, t->type); if (!btf_type_is_func_proto(t)) return -EINVAL; ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel); if (ret) return ret; break; default: if (!prog_extension) return -EINVAL; fallthrough; case BPF_MODIFY_RETURN: case BPF_LSM_MAC: case BPF_LSM_CGROUP: case BPF_TRACE_FENTRY: case BPF_TRACE_FEXIT: if (!btf_type_is_func(t)) { bpf_log(log, "attach_btf_id %u is not a function\n", btf_id); return -EINVAL; } if (prog_extension && btf_check_type_match(log, prog, btf, t)) return -EINVAL; t = btf_type_by_id(btf, t->type); if (!btf_type_is_func_proto(t)) return -EINVAL; if ((prog->aux->saved_dst_prog_type || prog->aux->saved_dst_attach_type) && (!tgt_prog || prog->aux->saved_dst_prog_type != tgt_prog->type || prog->aux->saved_dst_attach_type != tgt_prog->expected_attach_type)) return -EINVAL; if (tgt_prog && conservative) t = NULL; ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel); if (ret < 0) return ret; if (tgt_prog) { if (subprog == 0) addr = (long) tgt_prog->bpf_func; else addr = (long) tgt_prog->aux->func[subprog]->bpf_func; } else { if (btf_is_module(btf)) { mod = btf_try_get_module(btf); if (mod) addr = find_kallsyms_symbol_value(mod, tname); else addr = 0; } else { addr = kallsyms_lookup_name(tname); } if (!addr) { module_put(mod); bpf_log(log, "The address of function %s cannot be found\n", tname); return -ENOENT; } } if (prog->sleepable) { ret = -EINVAL; switch (prog->type) { case BPF_PROG_TYPE_TRACING: /* fentry/fexit/fmod_ret progs can be sleepable if they are * attached to ALLOW_ERROR_INJECTION and are not in denylist. */ if (!check_non_sleepable_error_inject(btf_id) && within_error_injection_list(addr)) ret = 0; /* fentry/fexit/fmod_ret progs can also be sleepable if they are * in the fmodret id set with the KF_SLEEPABLE flag. */ else { u32 *flags = btf_kfunc_is_modify_return(btf, btf_id, prog); if (flags && (*flags & KF_SLEEPABLE)) ret = 0; } break; case BPF_PROG_TYPE_LSM: /* LSM progs check that they are attached to bpf_lsm_*() funcs. * Only some of them are sleepable. */ if (bpf_lsm_is_sleepable_hook(btf_id)) ret = 0; break; default: break; } if (ret) { module_put(mod); bpf_log(log, "%s is not sleepable\n", tname); return ret; } } else if (prog->expected_attach_type == BPF_MODIFY_RETURN) { if (tgt_prog) { module_put(mod); bpf_log(log, "can't modify return codes of BPF programs\n"); return -EINVAL; } ret = -EINVAL; if (btf_kfunc_is_modify_return(btf, btf_id, prog) || !check_attach_modify_return(addr, tname)) ret = 0; if (ret) { module_put(mod); bpf_log(log, "%s() is not modifiable\n", tname); return ret; } } break; } tgt_info->tgt_addr = addr; tgt_info->tgt_name = tname; tgt_info->tgt_type = t; tgt_info->tgt_mod = mod; return 0; } BTF_SET_START(btf_id_deny) BTF_ID_UNUSED #ifdef CONFIG_SMP BTF_ID(func, migrate_disable) BTF_ID(func, migrate_enable) #endif #if !defined CONFIG_PREEMPT_RCU && !defined CONFIG_TINY_RCU BTF_ID(func, rcu_read_unlock_strict) #endif #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_TRACE_PREEMPT_TOGGLE) BTF_ID(func, preempt_count_add) BTF_ID(func, preempt_count_sub) #endif #ifdef CONFIG_PREEMPT_RCU BTF_ID(func, __rcu_read_lock) BTF_ID(func, __rcu_read_unlock) #endif BTF_SET_END(btf_id_deny) static bool can_be_sleepable(struct bpf_prog *prog) { if (prog->type == BPF_PROG_TYPE_TRACING) { switch (prog->expected_attach_type) { case BPF_TRACE_FENTRY: case BPF_TRACE_FEXIT: case BPF_MODIFY_RETURN: case BPF_TRACE_ITER: return true; default: return false; } } return prog->type == BPF_PROG_TYPE_LSM || prog->type == BPF_PROG_TYPE_KPROBE /* only for uprobes */ || prog->type == BPF_PROG_TYPE_STRUCT_OPS; } static int check_attach_btf_id(struct bpf_verifier_env *env) { struct bpf_prog *prog = env->prog; struct bpf_prog *tgt_prog = prog->aux->dst_prog; struct bpf_attach_target_info tgt_info = {}; u32 btf_id = prog->aux->attach_btf_id; struct bpf_trampoline *tr; int ret; u64 key; if (prog->type == BPF_PROG_TYPE_SYSCALL) { if (prog->sleepable) /* attach_btf_id checked to be zero already */ return 0; verbose(env, "Syscall programs can only be sleepable\n"); return -EINVAL; } if (prog->sleepable && !can_be_sleepable(prog)) { verbose(env, "Only fentry/fexit/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable\n"); return -EINVAL; } if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) return check_struct_ops_btf_id(env); if (prog->type != BPF_PROG_TYPE_TRACING && prog->type != BPF_PROG_TYPE_LSM && prog->type != BPF_PROG_TYPE_EXT) return 0; ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info); if (ret) return ret; if (tgt_prog && prog->type == BPF_PROG_TYPE_EXT) { /* to make freplace equivalent to their targets, they need to * inherit env->ops and expected_attach_type for the rest of the * verification */ env->ops = bpf_verifier_ops[tgt_prog->type]; prog->expected_attach_type = tgt_prog->expected_attach_type; } /* store info about the attachment target that will be used later */ prog->aux->attach_func_proto = tgt_info.tgt_type; prog->aux->attach_func_name = tgt_info.tgt_name; prog->aux->mod = tgt_info.tgt_mod; if (tgt_prog) { prog->aux->saved_dst_prog_type = tgt_prog->type; prog->aux->saved_dst_attach_type = tgt_prog->expected_attach_type; } if (prog->expected_attach_type == BPF_TRACE_RAW_TP) { prog->aux->attach_btf_trace = true; return 0; } else if (prog->expected_attach_type == BPF_TRACE_ITER) { if (!bpf_iter_prog_supported(prog)) return -EINVAL; return 0; } if (prog->type == BPF_PROG_TYPE_LSM) { ret = bpf_lsm_verify_prog(&env->log, prog); if (ret < 0) return ret; } else if (prog->type == BPF_PROG_TYPE_TRACING && btf_id_set_contains(&btf_id_deny, btf_id)) { return -EINVAL; } key = bpf_trampoline_compute_key(tgt_prog, prog->aux->attach_btf, btf_id); tr = bpf_trampoline_get(key, &tgt_info); if (!tr) return -ENOMEM; if (tgt_prog && tgt_prog->aux->tail_call_reachable) tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX; prog->aux->dst_trampoline = tr; return 0; } struct btf *bpf_get_btf_vmlinux(void) { if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) { mutex_lock(&bpf_verifier_lock); if (!btf_vmlinux) btf_vmlinux = btf_parse_vmlinux(); mutex_unlock(&bpf_verifier_lock); } return btf_vmlinux; } int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_size) { u64 start_time = ktime_get_ns(); struct bpf_verifier_env *env; int i, len, ret = -EINVAL, err; u32 log_true_size; bool is_priv; /* no program is valid */ if (ARRAY_SIZE(bpf_verifier_ops) == 0) return -EINVAL; /* 'struct bpf_verifier_env' can be global, but since it's not small, * allocate/free it every time bpf_check() is called */ env = kvzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); if (!env) return -ENOMEM; env->bt.env = env; len = (*prog)->len; env->insn_aux_data = vzalloc(array_size(sizeof(struct bpf_insn_aux_data), len)); ret = -ENOMEM; if (!env->insn_aux_data) goto err_free_env; for (i = 0; i < len; i++) env->insn_aux_data[i].orig_idx = i; env->prog = *prog; env->ops = bpf_verifier_ops[env->prog->type]; env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel); env->allow_ptr_leaks = bpf_allow_ptr_leaks(env->prog->aux->token); env->allow_uninit_stack = bpf_allow_uninit_stack(env->prog->aux->token); env->bypass_spec_v1 = bpf_bypass_spec_v1(env->prog->aux->token); env->bypass_spec_v4 = bpf_bypass_spec_v4(env->prog->aux->token); env->bpf_capable = is_priv = bpf_token_capable(env->prog->aux->token, CAP_BPF); bpf_get_btf_vmlinux(); /* grab the mutex to protect few globals used by verifier */ if (!is_priv) mutex_lock(&bpf_verifier_lock); /* user could have requested verbose verifier output * and supplied buffer to store the verification trace */ ret = bpf_vlog_init(&env->log, attr->log_level, (char __user *) (unsigned long) attr->log_buf, attr->log_size); if (ret) goto err_unlock; mark_verifier_state_clean(env); if (IS_ERR(btf_vmlinux)) { /* Either gcc or pahole or kernel are broken. */ verbose(env, "in-kernel BTF is malformed\n"); ret = PTR_ERR(btf_vmlinux); goto skip_full_check; } env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT); if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) env->strict_alignment = true; if (attr->prog_flags & BPF_F_ANY_ALIGNMENT) env->strict_alignment = false; if (is_priv) env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ; env->test_reg_invariants = attr->prog_flags & BPF_F_TEST_REG_INVARIANTS; env->explored_states = kvcalloc(state_htab_size(env), sizeof(struct bpf_verifier_state_list *), GFP_USER); ret = -ENOMEM; if (!env->explored_states) goto skip_full_check; ret = check_btf_info_early(env, attr, uattr); if (ret < 0) goto skip_full_check; ret = add_subprog_and_kfunc(env); if (ret < 0) goto skip_full_check; ret = check_subprogs(env); if (ret < 0) goto skip_full_check; ret = check_btf_info(env, attr, uattr); if (ret < 0) goto skip_full_check; ret = resolve_pseudo_ldimm64(env); if (ret < 0) goto skip_full_check; if (bpf_prog_is_offloaded(env->prog->aux)) { ret = bpf_prog_offload_verifier_prep(env->prog); if (ret) goto skip_full_check; } ret = check_cfg(env); if (ret < 0) goto skip_full_check; ret = check_attach_btf_id(env); if (ret) goto skip_full_check; ret = mark_fastcall_patterns(env); if (ret < 0) goto skip_full_check; ret = do_check_main(env); ret = ret ?: do_check_subprogs(env); if (ret == 0 && bpf_prog_is_offloaded(env->prog->aux)) ret = bpf_prog_offload_finalize(env); skip_full_check: kvfree(env->explored_states); /* might decrease stack depth, keep it before passes that * allocate additional slots. */ if (ret == 0) ret = remove_fastcall_spills_fills(env); if (ret == 0) ret = check_max_stack_depth(env); /* instruction rewrites happen after this point */ if (ret == 0) ret = optimize_bpf_loop(env); if (is_priv) { if (ret == 0) opt_hard_wire_dead_code_branches(env); if (ret == 0) ret = opt_remove_dead_code(env); if (ret == 0) ret = opt_remove_nops(env); } else { if (ret == 0) sanitize_dead_code(env); } if (ret == 0) /* program is valid, convert *(u32*)(ctx + off) accesses */ ret = convert_ctx_accesses(env); if (ret == 0) ret = do_misc_fixups(env); /* do 32-bit optimization after insn patching has done so those patched * insns could be handled correctly. */ if (ret == 0 && !bpf_prog_is_offloaded(env->prog->aux)) { ret = opt_subreg_zext_lo32_rnd_hi32(env, attr); env->prog->aux->verifier_zext = bpf_jit_needs_zext() ? !ret : false; } if (ret == 0) ret = fixup_call_args(env); env->verification_time = ktime_get_ns() - start_time; print_verification_stats(env); env->prog->aux->verified_insns = env->insn_processed; /* preserve original error even if log finalization is successful */ err = bpf_vlog_finalize(&env->log, &log_true_size); if (err) ret = err; if (uattr_size >= offsetofend(union bpf_attr, log_true_size) && copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, log_true_size), &log_true_size, sizeof(log_true_size))) { ret = -EFAULT; goto err_release_maps; } if (ret) goto err_release_maps; if (env->used_map_cnt) { /* if program passed verifier, update used_maps in bpf_prog_info */ env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, sizeof(env->used_maps[0]), GFP_KERNEL); if (!env->prog->aux->used_maps) { ret = -ENOMEM; goto err_release_maps; } memcpy(env->prog->aux->used_maps, env->used_maps, sizeof(env->used_maps[0]) * env->used_map_cnt); env->prog->aux->used_map_cnt = env->used_map_cnt; } if (env->used_btf_cnt) { /* if program passed verifier, update used_btfs in bpf_prog_aux */ env->prog->aux->used_btfs = kmalloc_array(env->used_btf_cnt, sizeof(env->used_btfs[0]), GFP_KERNEL); if (!env->prog->aux->used_btfs) { ret = -ENOMEM; goto err_release_maps; } memcpy(env->prog->aux->used_btfs, env->used_btfs, sizeof(env->used_btfs[0]) * env->used_btf_cnt); env->prog->aux->used_btf_cnt = env->used_btf_cnt; } if (env->used_map_cnt || env->used_btf_cnt) { /* program is valid. Convert pseudo bpf_ld_imm64 into generic * bpf_ld_imm64 instructions */ convert_pseudo_ld_imm64(env); } adjust_btf_func(env); err_release_maps: if (!env->prog->aux->used_maps) /* if we didn't copy map pointers into bpf_prog_info, release * them now. Otherwise free_used_maps() will release them. */ release_maps(env); if (!env->prog->aux->used_btfs) release_btfs(env); /* extension progs temporarily inherit the attach_type of their targets for verification purposes, so set it back to zero before returning */ if (env->prog->type == BPF_PROG_TYPE_EXT) env->prog->expected_attach_type = 0; *prog = env->prog; module_put(env->attach_btf_mod); err_unlock: if (!is_priv) mutex_unlock(&bpf_verifier_lock); vfree(env->insn_aux_data); kvfree(env->insn_hist); err_free_env: kvfree(env); return ret; }
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