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 pid_t target_pid;
13 u64 root_cg_id, leaf_cg_id;
14 u64 first_cg_id, last_cg_id;
15
16 int pre_order_cnt, post_order_cnt, tree_high;
17
18 struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
19 void bpf_cgroup_release(struct cgroup *p) __ksym;
20 void bpf_rcu_read_lock(void) __ksym;
21 void bpf_rcu_read_unlock(void) __ksym;
22
23 SEC("fentry.s/" SYS_PREFIX "sys_getpgid")
24 int iter_css_for_each(const void *ctx)
25 {
26 struct task_struct *cur_task = bpf_get_current_task_btf();
27 struct cgroup_subsys_state *root_css, *leaf_css, *pos;
28 struct cgroup *root_cgrp, *leaf_cgrp, *cur_cgrp;
29
30 if (cur_task->pid != target_pid)
31 return 0;
32
33 root_cgrp = bpf_cgroup_from_id(root_cg_id);
34
35 if (!root_cgrp)
36 return 0;
37
38 leaf_cgrp = bpf_cgroup_from_id(leaf_cg_id);
39
40 if (!leaf_cgrp) {
41 bpf_cgroup_release(root_cgrp);
42 return 0;
43 }
44 root_css = &root_cgrp->self;
45 leaf_css = &leaf_cgrp->self;
46 pre_order_cnt = post_order_cnt = tree_high = 0;
47 first_cg_id = last_cg_id = 0;
48
49 bpf_rcu_read_lock();
50 bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
51 cur_cgrp = pos->cgroup;
52 post_order_cnt++;
53 last_cg_id = cur_cgrp->kn->id;
54 }
55
56 bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_PRE) {
57 cur_cgrp = pos->cgroup;
58 pre_order_cnt++;
59 if (!first_cg_id)
60 first_cg_id = cur_cgrp->kn->id;
61 }
62
63 bpf_for_each(css, pos, leaf_css, BPF_CGROUP_ITER_ANCESTORS_UP)
64 tree_high++;
65
66 bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_ANCESTORS_UP)
67 tree_high--;
68 bpf_rcu_read_unlock();
69 bpf_cgroup_release(root_cgrp);
70 bpf_cgroup_release(leaf_cgrp);
71 return 0;
72 }
73
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