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#define _GNU_SOURCE
 9#include <stdio.h>
10#include <linux/bpf.h>
11#include <unistd.h>
12#include "libbpf.h"
13#include "bpf_load.h"
14#include <linux/bpf.h>
15#include "cgroup_helpers.h"
16
17#define CGROUP_PATH		"/my-cgroup"
18
19int main(int argc, char **argv)
20{
21	pid_t remote_pid, local_pid = getpid();
22	int cg2, idx = 0, rc = 0;
23	char filename[256];
24
25	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
26	if (load_bpf_file(filename)) {
27		printf("%s", bpf_log_buf);
28		return 1;
29	}
30
31	if (setup_cgroup_environment())
32		goto err;
33
34	cg2 = create_and_get_cgroup(CGROUP_PATH);
35
36	if (!cg2)
37		goto err;
38
39	if (bpf_map_update_elem(map_fd[0], &idx, &cg2, BPF_ANY)) {
40		log_err("Adding target cgroup to map");
41		goto err;
42	}
43
44	if (join_cgroup(CGROUP_PATH))
45		goto err;
46
47	/*
48	 * The installed helper program catched the sync call, and should
49	 * write it to the map.
50	 */
51
52	sync();
53	bpf_map_lookup_elem(map_fd[1], &idx, &remote_pid);
54
55	if (local_pid != remote_pid) {
56		fprintf(stderr,
57			"BPF Helper didn't write correct PID to map, but: %d\n",
58			remote_pid);
59		goto err;
60	}
61
62	/* Verify the negative scenario; leave the cgroup */
63	if (join_cgroup("/"))
64		goto err;
65
66	remote_pid = 0;
67	bpf_map_update_elem(map_fd[1], &idx, &remote_pid, BPF_ANY);
68
69	sync();
70	bpf_map_lookup_elem(map_fd[1], &idx, &remote_pid);
71
72	if (local_pid == remote_pid) {
73		fprintf(stderr, "BPF cgroup negative test did not work\n");
74		goto err;
75	}
76
77	goto out;
78err:
79	rc = 1;
80
81out:
82	close(cg2);
83	cleanup_cgroup_environment();
84	return rc;
85}