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 <unistd.h>
8#include <bpf/bpf.h>
9#include <bpf/libbpf.h>
10#include "cgroup_helpers.h"
11
12#define CGROUP_PATH		"/my-cgroup"
13
14int main(int argc, char **argv)
15{
16	pid_t remote_pid, local_pid = getpid();
17	int cg2 = -1, idx = 0, rc = 1;
18	struct bpf_link *link = NULL;
19	struct bpf_program *prog;
20	struct bpf_object *obj;
21	char filename[256];
22	int map_fd[2];
23
24	snprintf(filename, sizeof(filename), "%s.bpf.o", argv[0]);
25	obj = bpf_object__open_file(filename, NULL);
26	if (libbpf_get_error(obj)) {
27		fprintf(stderr, "ERROR: opening BPF object file failed\n");
28		return 0;
29	}
30
31	prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
32	if (!prog) {
33		printf("finding a prog in obj file failed\n");
34		goto cleanup;
35	}
36
37	/* load BPF program */
38	if (bpf_object__load(obj)) {
39		fprintf(stderr, "ERROR: loading BPF object file failed\n");
40		goto cleanup;
41	}
42
43	map_fd[0] = bpf_object__find_map_fd_by_name(obj, "cgroup_map");
44	map_fd[1] = bpf_object__find_map_fd_by_name(obj, "perf_map");
45	if (map_fd[0] < 0 || map_fd[1] < 0) {
46		fprintf(stderr, "ERROR: finding a map in obj file failed\n");
47		goto cleanup;
48	}
49
50	link = bpf_program__attach(prog);
51	if (libbpf_get_error(link)) {
52		fprintf(stderr, "ERROR: bpf_program__attach failed\n");
53		link = NULL;
54		goto cleanup;
55	}
56
57	if (setup_cgroup_environment())
58		goto err;
59
60	cg2 = create_and_get_cgroup(CGROUP_PATH);
61
62	if (cg2 < 0)
63		goto err;
64
65	if (bpf_map_update_elem(map_fd[0], &idx, &cg2, BPF_ANY)) {
66		log_err("Adding target cgroup to map");
67		goto err;
68	}
69
70	if (join_cgroup(CGROUP_PATH))
71		goto err;
72
73	/*
74	 * The installed helper program catched the sync call, and should
75	 * write it to the map.
76	 */
77
78	sync();
79	bpf_map_lookup_elem(map_fd[1], &idx, &remote_pid);
80
81	if (local_pid != remote_pid) {
82		fprintf(stderr,
83			"BPF Helper didn't write correct PID to map, but: %d\n",
84			remote_pid);
85		goto err;
86	}
87
88	/* Verify the negative scenario; leave the cgroup */
89	if (join_cgroup("/"))
90		goto err;
91
92	remote_pid = 0;
93	bpf_map_update_elem(map_fd[1], &idx, &remote_pid, BPF_ANY);
94
95	sync();
96	bpf_map_lookup_elem(map_fd[1], &idx, &remote_pid);
97
98	if (local_pid == remote_pid) {
99		fprintf(stderr, "BPF cgroup negative test did not work\n");
100		goto err;
101	}
102
103	rc = 0;
104
105err:
106	if (cg2 != -1)
107		close(cg2);
108
109	cleanup_cgroup_environment();
110
111cleanup:
112	bpf_link__destroy(link);
113	bpf_object__close(obj);
114	return rc;
115}
116