Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
3#include <vmlinux.h>
4#include <bpf/bpf_helpers.h>
5#include <bpf/bpf_tracing.h>
6#include "bpf_misc.h"
7
8char _license[] SEC("license") = "GPL";
9
10struct {
11 __uint(type, BPF_MAP_TYPE_CGRP_STORAGE);
12 __uint(map_flags, BPF_F_NO_PREALLOC);
13 __type(key, int);
14 __type(value, long);
15} map_a SEC(".maps");
16
17__s32 target_pid;
18__u64 cgroup_id;
19int target_hid;
20bool is_cgroup1;
21
22struct cgroup *bpf_task_get_cgroup1(struct task_struct *task, int hierarchy_id) __ksym;
23void bpf_cgroup_release(struct cgroup *cgrp) __ksym;
24void bpf_rcu_read_lock(void) __ksym;
25void bpf_rcu_read_unlock(void) __ksym;
26
27SEC("?iter.s/cgroup")
28int cgroup_iter(struct bpf_iter__cgroup *ctx)
29{
30 struct cgroup *cgrp = ctx->cgroup;
31 long *ptr;
32
33 if (cgrp == NULL)
34 return 0;
35
36 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
37 BPF_LOCAL_STORAGE_GET_F_CREATE);
38 if (ptr)
39 cgroup_id = cgrp->kn->id;
40 return 0;
41}
42
43static void __no_rcu_lock(struct cgroup *cgrp)
44{
45 long *ptr;
46
47 /* Note that trace rcu is held in sleepable prog, so we can use
48 * bpf_cgrp_storage_get() in sleepable prog.
49 */
50 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
51 BPF_LOCAL_STORAGE_GET_F_CREATE);
52 if (ptr)
53 cgroup_id = cgrp->kn->id;
54}
55
56SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
57int cgrp1_no_rcu_lock(void *ctx)
58{
59 struct task_struct *task;
60 struct cgroup *cgrp;
61
62 task = bpf_get_current_task_btf();
63 if (task->pid != target_pid)
64 return 0;
65
66 /* bpf_task_get_cgroup1 can work in sleepable prog */
67 cgrp = bpf_task_get_cgroup1(task, target_hid);
68 if (!cgrp)
69 return 0;
70
71 __no_rcu_lock(cgrp);
72 bpf_cgroup_release(cgrp);
73 return 0;
74}
75
76SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
77int no_rcu_lock(void *ctx)
78{
79 struct task_struct *task;
80
81 task = bpf_get_current_task_btf();
82 if (task->pid != target_pid)
83 return 0;
84
85 /* task->cgroups is untrusted in sleepable prog outside of RCU CS */
86 __no_rcu_lock(task->cgroups->dfl_cgrp);
87 return 0;
88}
89
90SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
91int yes_rcu_lock(void *ctx)
92{
93 struct task_struct *task;
94 struct cgroup *cgrp;
95 long *ptr;
96
97 task = bpf_get_current_task_btf();
98 if (task->pid != target_pid)
99 return 0;
100
101 if (is_cgroup1) {
102 bpf_rcu_read_lock();
103 cgrp = bpf_task_get_cgroup1(task, target_hid);
104 if (!cgrp) {
105 bpf_rcu_read_unlock();
106 return 0;
107 }
108
109 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE);
110 if (ptr)
111 cgroup_id = cgrp->kn->id;
112 bpf_cgroup_release(cgrp);
113 bpf_rcu_read_unlock();
114 return 0;
115 }
116
117 bpf_rcu_read_lock();
118 cgrp = task->cgroups->dfl_cgrp;
119 /* cgrp is trusted under RCU CS */
120 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE);
121 if (ptr)
122 cgroup_id = cgrp->kn->id;
123 bpf_rcu_read_unlock();
124 return 0;
125}