// SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ #include "bpf_iter.h" #include <bpf/bpf_helpers.h> #include <bpf/bpf_tracing.h> #include "bpf_misc.h" char _license[] SEC("license") = "GPL"; struct { __uint(type, BPF_MAP_TYPE_CGRP_STORAGE); __uint(map_flags, BPF_F_NO_PREALLOC); __type(key, int); __type(value, long); } map_a SEC(".maps"); __u32 target_pid; __u64 cgroup_id; void bpf_rcu_read_lock(void) __ksym; void bpf_rcu_read_unlock(void) __ksym; SEC("?iter.s/cgroup") int cgroup_iter(struct bpf_iter__cgroup *ctx) { struct cgroup *cgrp = ctx->cgroup; long *ptr; if (cgrp == NULL) return 0; ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); if (ptr) cgroup_id = cgrp->kn->id; return 0; } SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") int no_rcu_lock(void *ctx) { struct task_struct *task; struct cgroup *cgrp; long *ptr; task = bpf_get_current_task_btf(); if (task->pid != target_pid) return 0; /* task->cgroups is untrusted in sleepable prog outside of RCU CS */ cgrp = task->cgroups->dfl_cgrp; ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); if (ptr) cgroup_id = cgrp->kn->id; return 0; } SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") int yes_rcu_lock(void *ctx) { struct task_struct *task; struct cgroup *cgrp; long *ptr; task = bpf_get_current_task_btf(); if (task->pid != target_pid) return 0; bpf_rcu_read_lock(); cgrp = task->cgroups->dfl_cgrp; /* cgrp is trusted under RCU CS */ ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); if (ptr) cgroup_id = cgrp->kn->id; bpf_rcu_read_unlock(); return 0; }