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
14 int 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
105 err:
106 if (cg2 != -1)
107 close(cg2);
108
109 cleanup_cgroup_environment();
110
111 cleanup:
112 bpf_link__destroy(link);
113 bpf_object__close(obj);
114 return rc;
115 }
116
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