1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
3
4 #include "vmlinux.h"
5 #include <bpf/bpf_helpers.h>
6 #include <bpf/bpf_tracing.h>
7 #include "bpf_misc.h"
8 #include "bpf_experimental.h"
9
10 char _license[] SEC("license") = "GPL";
11
12 struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
13 void bpf_cgroup_release(struct cgroup *p) __ksym;
14 void bpf_rcu_read_lock(void) __ksym;
15 void bpf_rcu_read_unlock(void) __ksym;
16
17 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
18 __failure __msg("expected an RCU CS when using bpf_iter_task_next")
19 int BPF_PROG(iter_tasks_without_lock)
20 {
21 struct task_struct *pos;
22
23 bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS) {
24
25 }
26 return 0;
27 }
28
29 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
30 __failure __msg("expected an RCU CS when using bpf_iter_css_next")
31 int BPF_PROG(iter_css_without_lock)
32 {
33 u64 cg_id = bpf_get_current_cgroup_id();
34 struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
35 struct cgroup_subsys_state *root_css, *pos;
36
37 if (!cgrp)
38 return 0;
39 root_css = &cgrp->self;
40
41 bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
42
43 }
44 bpf_cgroup_release(cgrp);
45 return 0;
46 }
47
48 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
49 __failure __msg("expected an RCU CS when using bpf_iter_task_next")
50 int BPF_PROG(iter_tasks_lock_and_unlock)
51 {
52 struct task_struct *pos;
53
54 bpf_rcu_read_lock();
55 bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS) {
56 bpf_rcu_read_unlock();
57
58 bpf_rcu_read_lock();
59 }
60 bpf_rcu_read_unlock();
61 return 0;
62 }
63
64 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
65 __failure __msg("expected an RCU CS when using bpf_iter_css_next")
66 int BPF_PROG(iter_css_lock_and_unlock)
67 {
68 u64 cg_id = bpf_get_current_cgroup_id();
69 struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
70 struct cgroup_subsys_state *root_css, *pos;
71
72 if (!cgrp)
73 return 0;
74 root_css = &cgrp->self;
75
76 bpf_rcu_read_lock();
77 bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
78 bpf_rcu_read_unlock();
79
80 bpf_rcu_read_lock();
81 }
82 bpf_rcu_read_unlock();
83 bpf_cgroup_release(cgrp);
84 return 0;
85 }
86
87 SEC("?fentry/" SYS_PREFIX "sys_getpgid")
88 __failure __msg("css_task_iter is only allowed in bpf_lsm, bpf_iter and sleepable progs")
89 int BPF_PROG(iter_css_task_for_each)
90 {
91 u64 cg_id = bpf_get_current_cgroup_id();
92 struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
93 struct cgroup_subsys_state *css;
94 struct task_struct *task;
95
96 if (cgrp == NULL)
97 return 0;
98 css = &cgrp->self;
99
100 bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) {
101
102 }
103 bpf_cgroup_release(cgrp);
104 return 0;
105 }
106
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.