| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Andrew Lutomirski | 1240 | 85.64% | 24 | 48.98% |
| Rik Van Riel | 30 | 2.07% | 1 | 2.04% |
| Dominik Brodowski | 24 | 1.66% | 2 | 4.08% |
| Thomas Gleixner | 23 | 1.59% | 3 | 6.12% |
| Dan J Williams | 21 | 1.45% | 1 | 2.04% |
| Kees Cook | 21 | 1.45% | 1 | 2.04% |
| Linus Torvalds | 19 | 1.31% | 2 | 4.08% |
| Sudeep Holla | 13 | 0.90% | 1 | 2.04% |
| Miroslav Benes | 11 | 0.76% | 1 | 2.04% |
| Brian Gerst | 10 | 0.69% | 1 | 2.04% |
| Mathieu Desnoyers | 10 | 0.69% | 1 | 2.04% |
| Thomas Garnier | 6 | 0.41% | 1 | 2.04% |
| Josh Poimboeuf | 4 | 0.28% | 1 | 2.04% |
| Ingo Molnar | 4 | 0.28% | 2 | 4.08% |
| Benjamin Thiel | 3 | 0.21% | 1 | 2.04% |
| Paolo Bonzini | 3 | 0.21% | 2 | 4.08% |
| Borislav Petkov | 2 | 0.14% | 1 | 2.04% |
| Will Deacon | 2 | 0.14% | 1 | 2.04% |
| Mark Rutland | 1 | 0.07% | 1 | 2.04% |
| Frédéric Weisbecker | 1 | 0.07% | 1 | 2.04% |
| Total | 1448 | 49 |
// SPDX-License-Identifier: GPL-2.0-only /* * common.c - C code for kernel entry and exit * Copyright (c) 2015 Andrew Lutomirski * * Based on asm and ptrace code by many authors. The code here originated * in ptrace.c and signal.c. */ #include <linux/kernel.h> #include <linux/sched.h> #include <linux/sched/task_stack.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/errno.h> #include <linux/ptrace.h> #include <linux/tracehook.h> #include <linux/audit.h> #include <linux/seccomp.h> #include <linux/signal.h> #include <linux/export.h> #include <linux/context_tracking.h> #include <linux/user-return-notifier.h> #include <linux/nospec.h> #include <linux/uprobes.h> #include <linux/livepatch.h> #include <linux/syscalls.h> #include <linux/uaccess.h> #include <asm/desc.h> #include <asm/traps.h> #include <asm/vdso.h> #include <asm/cpufeature.h> #include <asm/fpu/api.h> #include <asm/nospec-branch.h> #include <asm/io_bitmap.h> #include <asm/syscall.h> #define CREATE_TRACE_POINTS #include <trace/events/syscalls.h> #ifdef CONFIG_CONTEXT_TRACKING /* Called on entry from user mode with IRQs off. */ __visible inline void enter_from_user_mode(void) { CT_WARN_ON(ct_state() != CONTEXT_USER); user_exit_irqoff(); } #else static inline void enter_from_user_mode(void) {} #endif static void do_audit_syscall_entry(struct pt_regs *regs, u32 arch) { #ifdef CONFIG_X86_64 if (arch == AUDIT_ARCH_X86_64) { audit_syscall_entry(regs->orig_ax, regs->di, regs->si, regs->dx, regs->r10); } else #endif { audit_syscall_entry(regs->orig_ax, regs->bx, regs->cx, regs->dx, regs->si); } } /* * Returns the syscall nr to run (which should match regs->orig_ax) or -1 * to skip the syscall. */ static long syscall_trace_enter(struct pt_regs *regs) { u32 arch = in_ia32_syscall() ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64; struct thread_info *ti = current_thread_info(); unsigned long ret = 0; u32 work; if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) BUG_ON(regs != task_pt_regs(current)); work = READ_ONCE(ti->flags); if (work & (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU)) { ret = tracehook_report_syscall_entry(regs); if (ret || (work & _TIF_SYSCALL_EMU)) return -1L; } #ifdef CONFIG_SECCOMP /* * Do seccomp after ptrace, to catch any tracer changes. */ if (work & _TIF_SECCOMP) { struct seccomp_data sd; sd.arch = arch; sd.nr = regs->orig_ax; sd.instruction_pointer = regs->ip; #ifdef CONFIG_X86_64 if (arch == AUDIT_ARCH_X86_64) { sd.args[0] = regs->di; sd.args[1] = regs->si; sd.args[2] = regs->dx; sd.args[3] = regs->r10; sd.args[4] = regs->r8; sd.args[5] = regs->r9; } else #endif { sd.args[0] = regs->bx; sd.args[1] = regs->cx; sd.args[2] = regs->dx; sd.args[3] = regs->si; sd.args[4] = regs->di; sd.args[5] = regs->bp; } ret = __secure_computing(&sd); if (ret == -1) return ret; } #endif if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT))) trace_sys_enter(regs, regs->orig_ax); do_audit_syscall_entry(regs, arch); return ret ?: regs->orig_ax; } #define EXIT_TO_USERMODE_LOOP_FLAGS \ (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ _TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY | _TIF_PATCH_PENDING) static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags) { /* * In order to return to user mode, we need to have IRQs off with * none of EXIT_TO_USERMODE_LOOP_FLAGS set. Several of these flags * can be set at any time on preemptible kernels if we have IRQs on, * so we need to loop. Disabling preemption wouldn't help: doing the * work to clear some of the flags can sleep. */ while (true) { /* We have work to do. */ local_irq_enable(); if (cached_flags & _TIF_NEED_RESCHED) schedule(); if (cached_flags & _TIF_UPROBE) uprobe_notify_resume(regs); if (cached_flags & _TIF_PATCH_PENDING) klp_update_patch_state(current); /* deal with pending signal delivery */ if (cached_flags & _TIF_SIGPENDING) do_signal(regs); if (cached_flags & _TIF_NOTIFY_RESUME) { clear_thread_flag(TIF_NOTIFY_RESUME); tracehook_notify_resume(regs); rseq_handle_notify_resume(NULL, regs); } if (cached_flags & _TIF_USER_RETURN_NOTIFY) fire_user_return_notifiers(); /* Disable IRQs and retry */ local_irq_disable(); cached_flags = READ_ONCE(current_thread_info()->flags); if (!(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS)) break; } } /* Called with IRQs disabled. */ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs) { struct thread_info *ti = current_thread_info(); u32 cached_flags; addr_limit_user_check(); lockdep_assert_irqs_disabled(); lockdep_sys_exit(); cached_flags = READ_ONCE(ti->flags); if (unlikely(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS)) exit_to_usermode_loop(regs, cached_flags); /* Reload ti->flags; we may have rescheduled above. */ cached_flags = READ_ONCE(ti->flags); if (unlikely(cached_flags & _TIF_IO_BITMAP)) tss_update_io_bitmap(); fpregs_assert_state_consistent(); if (unlikely(cached_flags & _TIF_NEED_FPU_LOAD)) switch_fpu_return(); #ifdef CONFIG_COMPAT /* * Compat syscalls set TS_COMPAT. Make sure we clear it before * returning to user mode. We need to clear it *after* signal * handling, because syscall restart has a fixup for compat * syscalls. The fixup is exercised by the ptrace_syscall_32 * selftest. * * We also need to clear TS_REGS_POKED_I386: the 32-bit tracer * special case only applies after poking regs and before the * very next return to user mode. */ ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED); #endif user_enter_irqoff(); mds_user_clear_cpu_buffers(); } #define SYSCALL_EXIT_WORK_FLAGS \ (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT) static void syscall_slow_exit_work(struct pt_regs *regs, u32 cached_flags) { bool step; audit_syscall_exit(regs); if (cached_flags & _TIF_SYSCALL_TRACEPOINT) trace_sys_exit(regs, regs->ax); /* * If TIF_SYSCALL_EMU is set, we only get here because of * TIF_SINGLESTEP (i.e. this is PTRACE_SYSEMU_SINGLESTEP). * We already reported this syscall instruction in * syscall_trace_enter(). */ step = unlikely( (cached_flags & (_TIF_SINGLESTEP | _TIF_SYSCALL_EMU)) == _TIF_SINGLESTEP); if (step || cached_flags & _TIF_SYSCALL_TRACE) tracehook_report_syscall_exit(regs, step); } /* * Called with IRQs on and fully valid regs. Returns with IRQs off in a * state such that we can immediately switch to user mode. */ __visible inline void syscall_return_slowpath(struct pt_regs *regs) { struct thread_info *ti = current_thread_info(); u32 cached_flags = READ_ONCE(ti->flags); CT_WARN_ON(ct_state() != CONTEXT_KERNEL); if (IS_ENABLED(CONFIG_PROVE_LOCKING) && WARN(irqs_disabled(), "syscall %ld left IRQs disabled", regs->orig_ax)) local_irq_enable(); rseq_syscall(regs); /* * First do one-time work. If these work items are enabled, we * want to run them exactly once per syscall exit with IRQs on. */ if (unlikely(cached_flags & SYSCALL_EXIT_WORK_FLAGS)) syscall_slow_exit_work(regs, cached_flags); local_irq_disable(); prepare_exit_to_usermode(regs); } #ifdef CONFIG_X86_64 __visible void do_syscall_64(unsigned long nr, struct pt_regs *regs) { struct thread_info *ti; enter_from_user_mode(); local_irq_enable(); ti = current_thread_info(); if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY) nr = syscall_trace_enter(regs); if (likely(nr < NR_syscalls)) { nr = array_index_nospec(nr, NR_syscalls); regs->ax = sys_call_table[nr](regs); #ifdef CONFIG_X86_X32_ABI } else if (likely((nr & __X32_SYSCALL_BIT) && (nr & ~__X32_SYSCALL_BIT) < X32_NR_syscalls)) { nr = array_index_nospec(nr & ~__X32_SYSCALL_BIT, X32_NR_syscalls); regs->ax = x32_sys_call_table[nr](regs); #endif } syscall_return_slowpath(regs); } #endif #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) /* * Does a 32-bit syscall. Called with IRQs on in CONTEXT_KERNEL. Does * all entry and exit work and returns with IRQs off. This function is * extremely hot in workloads that use it, and it's usually called from * do_fast_syscall_32, so forcibly inline it to improve performance. */ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs) { struct thread_info *ti = current_thread_info(); unsigned int nr = (unsigned int)regs->orig_ax; #ifdef CONFIG_IA32_EMULATION ti->status |= TS_COMPAT; #endif if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY) { /* * Subtlety here: if ptrace pokes something larger than * 2^32-1 into orig_ax, this truncates it. This may or * may not be necessary, but it matches the old asm * behavior. */ nr = syscall_trace_enter(regs); } if (likely(nr < IA32_NR_syscalls)) { nr = array_index_nospec(nr, IA32_NR_syscalls); regs->ax = ia32_sys_call_table[nr](regs); } syscall_return_slowpath(regs); } /* Handles int $0x80 */ __visible void do_int80_syscall_32(struct pt_regs *regs) { enter_from_user_mode(); local_irq_enable(); do_syscall_32_irqs_on(regs); } /* Returns 0 to return using IRET or 1 to return using SYSEXIT/SYSRETL. */ __visible long do_fast_syscall_32(struct pt_regs *regs) { /* * Called using the internal vDSO SYSENTER/SYSCALL32 calling * convention. Adjust regs so it looks like we entered using int80. */ unsigned long landing_pad = (unsigned long)current->mm->context.vdso + vdso_image_32.sym_int80_landing_pad; /* * SYSENTER loses EIP, and even SYSCALL32 needs us to skip forward * so that 'regs->ip -= 2' lands back on an int $0x80 instruction. * Fix it up. */ regs->ip = landing_pad; enter_from_user_mode(); local_irq_enable(); /* Fetch EBP from where the vDSO stashed it. */ if ( #ifdef CONFIG_X86_64 /* * Micro-optimization: the pointer we're following is explicitly * 32 bits, so it can't be out of range. */ __get_user(*(u32 *)®s->bp, (u32 __user __force *)(unsigned long)(u32)regs->sp) #else get_user(*(u32 *)®s->bp, (u32 __user __force *)(unsigned long)(u32)regs->sp) #endif ) { /* User code screwed up. */ local_irq_disable(); regs->ax = -EFAULT; prepare_exit_to_usermode(regs); return 0; /* Keep it simple: use IRET. */ } /* Now this is just like a normal syscall. */ do_syscall_32_irqs_on(regs); #ifdef CONFIG_X86_64 /* * Opportunistic SYSRETL: if possible, try to return using SYSRETL. * SYSRETL is available on all 64-bit CPUs, so we don't need to * bother with SYSEXIT. * * Unlike 64-bit opportunistic SYSRET, we can't check that CX == IP, * because the ECX fixup above will ensure that this is essentially * never the case. */ return regs->cs == __USER32_CS && regs->ss == __USER_DS && regs->ip == landing_pad && (regs->flags & (X86_EFLAGS_RF | X86_EFLAGS_TF)) == 0; #else /* * Opportunistic SYSEXIT: if possible, try to return using SYSEXIT. * * Unlike 64-bit opportunistic SYSRET, we can't check that CX == IP, * because the ECX fixup above will ensure that this is essentially * never the case. * * We don't allow syscalls at all from VM86 mode, but we still * need to check VM, because we might be returning from sys_vm86. */ return static_cpu_has(X86_FEATURE_SEP) && regs->cs == __USER_CS && regs->ss == __USER_DS && regs->ip == landing_pad && (regs->flags & (X86_EFLAGS_RF | X86_EFLAGS_TF | X86_EFLAGS_VM)) == 0; #endif } #endif SYSCALL_DEFINE0(ni_syscall) { return -ENOSYS; }