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	struct bpf_link *link = NULL;
 18	struct bpf_program *prog;
 19	int cg2, idx = 0, rc = 1;
 20	struct bpf_object *obj;
 21	char filename[256];
 22	int map_fd[2];
 23
 24	snprintf(filename, sizeof(filename), "%s_kern.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	close(cg2);
107	cleanup_cgroup_environment();
108
109cleanup:
110	bpf_link__destroy(link);
111	bpf_object__close(obj);
112	return rc;
113}