1// SPDX-License-Identifier: GPL-2.0-only
 2/* Copyright (c) 2016 Sargun Dhillon <sargun@sargun.me>
 3 */
 4
 5#define _GNU_SOURCE
 6#include <stdio.h>
 7#include <linux/bpf.h>
 8#include <unistd.h>
 9#include <bpf/bpf.h>
10#include "bpf_load.h"
11#include "cgroup_helpers.h"
12
13#define CGROUP_PATH		"/my-cgroup"
14
15int main(int argc, char **argv)
16{
17	pid_t remote_pid, local_pid = getpid();
18	int cg2, idx = 0, rc = 0;
19	char filename[256];
20
21	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
22	if (load_bpf_file(filename)) {
23		printf("%s", bpf_log_buf);
24		return 1;
25	}
26
27	if (setup_cgroup_environment())
28		goto err;
29
30	cg2 = create_and_get_cgroup(CGROUP_PATH);
31
32	if (cg2 < 0)
33		goto err;
34
35	if (bpf_map_update_elem(map_fd[0], &idx, &cg2, BPF_ANY)) {
36		log_err("Adding target cgroup to map");
37		goto err;
38	}
39
40	if (join_cgroup(CGROUP_PATH))
41		goto err;
42
43	/*
44	 * The installed helper program catched the sync call, and should
45	 * write it to the map.
46	 */
47
48	sync();
49	bpf_map_lookup_elem(map_fd[1], &idx, &remote_pid);
50
51	if (local_pid != remote_pid) {
52		fprintf(stderr,
53			"BPF Helper didn't write correct PID to map, but: %d\n",
54			remote_pid);
55		goto err;
56	}
57
58	/* Verify the negative scenario; leave the cgroup */
59	if (join_cgroup("/"))
60		goto err;
61
62	remote_pid = 0;
63	bpf_map_update_elem(map_fd[1], &idx, &remote_pid, BPF_ANY);
64
65	sync();
66	bpf_map_lookup_elem(map_fd[1], &idx, &remote_pid);
67
68	if (local_pid == remote_pid) {
69		fprintf(stderr, "BPF cgroup negative test did not work\n");
70		goto err;
71	}
72
73	goto out;
74err:
75	rc = 1;
76
77out:
78	close(cg2);
79	cleanup_cgroup_environment();
80	return rc;
81}