1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ 3 4 #include "bpf_iter.h" 5 #include <bpf/bpf_helpers.h> 6 #include <bpf/bpf_tracing.h> 7 #include "bpf_misc.h" 8 9 char _license[] SEC("license") = "GPL"; 10 11 struct { 12 __uint(type, BPF_MAP_TYPE_CGRP_STORAGE); 13 __uint(map_flags, BPF_F_NO_PREALLOC); 14 __type(key, int); 15 __type(value, long); 16 } map_a SEC(".maps"); 17 18 __u32 target_pid; 19 __u64 cgroup_id; 20 21 void bpf_rcu_read_lock(void) __ksym; 22 void bpf_rcu_read_unlock(void) __ksym; 23 24 SEC("?iter.s/cgroup") 25 int cgroup_iter(struct bpf_iter__cgroup *ctx) 26 { 27 struct cgroup *cgrp = ctx->cgroup; 28 long *ptr; 29 30 if (cgrp == NULL) 31 return 0; 32 33 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, 34 BPF_LOCAL_STORAGE_GET_F_CREATE); 35 if (ptr) 36 cgroup_id = cgrp->kn->id; 37 return 0; 38 } 39 40 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") 41 int no_rcu_lock(void *ctx) 42 { 43 struct task_struct *task; 44 struct cgroup *cgrp; 45 long *ptr; 46 47 task = bpf_get_current_task_btf(); 48 if (task->pid != target_pid) 49 return 0; 50 51 /* task->cgroups is untrusted in sleepable prog outside of RCU CS */ 52 cgrp = task->cgroups->dfl_cgrp; 53 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, 54 BPF_LOCAL_STORAGE_GET_F_CREATE); 55 if (ptr) 56 cgroup_id = cgrp->kn->id; 57 return 0; 58 } 59 60 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") 61 int yes_rcu_lock(void *ctx) 62 { 63 struct task_struct *task; 64 struct cgroup *cgrp; 65 long *ptr; 66 67 task = bpf_get_current_task_btf(); 68 if (task->pid != target_pid) 69 return 0; 70 71 bpf_rcu_read_lock(); 72 cgrp = task->cgroups->dfl_cgrp; 73 /* cgrp is trusted under RCU CS */ 74 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); 75 if (ptr) 76 cgroup_id = cgrp->kn->id; 77 bpf_rcu_read_unlock(); 78 return 0; 79 } 80