1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
3
4#include "vmlinux.h"
5#include <errno.h>
6#include <bpf/bpf_helpers.h>
7#include <bpf/bpf_tracing.h>
8#include "bpf_misc.h"
9#include "bpf_experimental.h"
10
11char _license[] SEC("license") = "GPL";
12
13struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
14struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
15void bpf_cgroup_release(struct cgroup *p) __ksym;
16
17pid_t target_pid;
18int css_task_cnt;
19u64 cg_id;
20
21SEC("lsm/file_mprotect")
22int BPF_PROG(iter_css_task_for_each, struct vm_area_struct *vma,
23 unsigned long reqprot, unsigned long prot, int ret)
24{
25 struct task_struct *cur_task = bpf_get_current_task_btf();
26 struct cgroup_subsys_state *css;
27 struct task_struct *task;
28 struct cgroup *cgrp;
29
30 if (cur_task->pid != target_pid)
31 return ret;
32
33 cgrp = bpf_cgroup_from_id(cg_id);
34
35 if (!cgrp)
36 return -EPERM;
37
38 css = &cgrp->self;
39 css_task_cnt = 0;
40
41 bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS)
42 if (task->pid == target_pid)
43 css_task_cnt++;
44
45 bpf_cgroup_release(cgrp);
46
47 return -EPERM;
48}
49
50static inline u64 cgroup_id(struct cgroup *cgrp)
51{
52 return cgrp->kn->id;
53}
54
55SEC("?iter/cgroup")
56int cgroup_id_printer(struct bpf_iter__cgroup *ctx)
57{
58 struct seq_file *seq = ctx->meta->seq;
59 struct cgroup *cgrp = ctx->cgroup;
60 struct cgroup_subsys_state *css;
61 struct task_struct *task;
62
63 /* epilogue */
64 if (cgrp == NULL) {
65 BPF_SEQ_PRINTF(seq, "epilogue\n");
66 return 0;
67 }
68
69 /* prologue */
70 if (ctx->meta->seq_num == 0)
71 BPF_SEQ_PRINTF(seq, "prologue\n");
72
73 BPF_SEQ_PRINTF(seq, "%8llu\n", cgroup_id(cgrp));
74
75 css = &cgrp->self;
76 css_task_cnt = 0;
77 bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) {
78 if (task->pid == target_pid)
79 css_task_cnt++;
80 }
81
82 return 0;
83}
84
85SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
86int BPF_PROG(iter_css_task_for_each_sleep)
87{
88 u64 cgrp_id = bpf_get_current_cgroup_id();
89 struct cgroup *cgrp = bpf_cgroup_from_id(cgrp_id);
90 struct cgroup_subsys_state *css;
91 struct task_struct *task;
92
93 if (cgrp == NULL)
94 return 0;
95 css = &cgrp->self;
96
97 bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) {
98
99 }
100 bpf_cgroup_release(cgrp);
101 return 0;
102}
103

source code of linux/tools/testing/selftests/bpf/progs/iters_css_task.c