LXR linux/samples/bpf/test_current_task_under_cgroup

   1/* Copyright (c) 2016 Sargun Dhillon <sargun@sargun.me>
   2 *
   3 * This program is free software; you can redistribute it and/or
   4 * modify it under the terms of version 2 of the GNU General Public
   5 * License as published by the Free Software Foundation.
   6 */
   7
   8#include <linux/ptrace.h>
   9#include <uapi/linux/bpf.h>
  10#include <linux/version.h>
  11#include <bpf/bpf_helpers.h>
  12#include <uapi/linux/utsname.h>
  13
  14struct bpf_map_def SEC("maps") cgroup_map = {
  15        .type                   = BPF_MAP_TYPE_CGROUP_ARRAY,
  16        .key_size               = sizeof(u32),
  17        .value_size             = sizeof(u32),
  18        .max_entries    = 1,
  19};
  20
  21struct bpf_map_def SEC("maps") perf_map = {
  22        .type                   = BPF_MAP_TYPE_ARRAY,
  23        .key_size               = sizeof(u32),
  24        .value_size             = sizeof(u64),
  25        .max_entries    = 1,
  26};
  27
  28/* Writes the last PID that called sync to a map at index 0 */
  29SEC("kprobe/sys_sync")
  30int bpf_prog1(struct pt_regs *ctx)
  31{
  32        u64 pid = bpf_get_current_pid_tgid();
  33        int idx = 0;
  34
  35        if (!bpf_current_task_under_cgroup(&cgroup_map, 0))
  36                return 0;
  37
  38        bpf_map_update_elem(&perf_map, &idx, &pid, BPF_ANY);
  39        return 0;
  40}
  41
  42char _license[] SEC("license") = "GPL";
  43u32 _version SEC("version") = LINUX_VERSION_CODE;
  44