samples/bpf/test_current_task_under_cgroup_kern.c

   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_helpers.h"
  12 #include <uapi/linux/utsname.h>
  13
  14 struct 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
  21 struct 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 */
  29 SEC("kprobe/sys_sync")
  30 int 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
  42 char _license[] SEC("license") = "GPL";
  43 u32 _version SEC("version") = LINUX_VERSION_CODE;