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 seq_file *seq = ctx->meta->seq; 28 struct cgroup *cgrp = ctx->cgroup; 29 long *ptr; 30 31 if (cgrp == NULL) 32 return 0; 33 34 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, 35 BPF_LOCAL_STORAGE_GET_F_CREATE); 36 if (ptr) 37 cgroup_id = cgrp->kn->id; 38 return 0; 39 } 40 41 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") 42 int no_rcu_lock(void *ctx) 43 { 44 struct task_struct *task; 45 struct cgroup *cgrp; 46 long *ptr; 47 48 task = bpf_get_current_task_btf(); 49 if (task->pid != target_pid) 50 return 0; 51 52 /* ptr_to_btf_id semantics. should work. */ 53 cgrp = task->cgroups->dfl_cgrp; 54 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, 55 BPF_LOCAL_STORAGE_GET_F_CREATE); 56 if (ptr) 57 cgroup_id = cgrp->kn->id; 58 return 0; 59 } 60 61 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") 62 int yes_rcu_lock(void *ctx) 63 { 64 struct task_struct *task; 65 struct cgroup *cgrp; 66 long *ptr; 67 68 task = bpf_get_current_task_btf(); 69 if (task->pid != target_pid) 70 return 0; 71 72 bpf_rcu_read_lock(); 73 cgrp = task->cgroups->dfl_cgrp; 74 /* cgrp is untrusted and cannot pass to bpf_cgrp_storage_get() helper. */ 75 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); 76 if (ptr) 77 cgroup_id = cgrp->kn->id; 78 bpf_rcu_read_unlock(); 79 return 0; 80 } 81