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