1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2017 Facebook
3  */
4 
5 #include <stdio.h>
6 #include <stdlib.h>
7 #include <string.h>
8 #include <errno.h>
9 #include <assert.h>
10 #include <sys/time.h>
11 
12 #include <linux/bpf.h>
13 #include <bpf/bpf.h>
14 #include <bpf/libbpf.h>
15 
16 #include "cgroup_helpers.h"
17 #include "testing_helpers.h"
18 
19 #define DEV_CGROUP_PROG "./dev_cgroup.o"
20 
21 #define TEST_CGROUP "/test-bpf-based-device-cgroup/"
22 
23 int main(int argc, char **argv)
24 {
25 	struct bpf_object *obj;
26 	int error = EXIT_FAILURE;
27 	int prog_fd, cgroup_fd;
28 	__u32 prog_cnt;
29 
30 	/* Use libbpf 1.0 API mode */
31 	libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
32 
33 	if (bpf_prog_test_load(DEV_CGROUP_PROG, BPF_PROG_TYPE_CGROUP_DEVICE,
34 			  &obj, &prog_fd)) {
35 		printf("Failed to load DEV_CGROUP program\n");
36 		goto out;
37 	}
38 
39 	cgroup_fd = cgroup_setup_and_join(TEST_CGROUP);
40 	if (cgroup_fd < 0) {
41 		printf("Failed to create test cgroup\n");
42 		goto out;
43 	}
44 
45 	/* Attach bpf program */
46 	if (bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_DEVICE, 0)) {
47 		printf("Failed to attach DEV_CGROUP program");
48 		goto err;
49 	}
50 
51 	if (bpf_prog_query(cgroup_fd, BPF_CGROUP_DEVICE, 0, NULL, NULL,
52 			   &prog_cnt)) {
53 		printf("Failed to query attached programs");
54 		goto err;
55 	}
56 
57 	/* All operations with /dev/zero and and /dev/urandom are allowed,
58 	 * everything else is forbidden.
59 	 */
60 	assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
61 	assert(system("mknod /tmp/test_dev_cgroup_null c 1 3"));
62 	assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
63 
64 	/* /dev/zero is whitelisted */
65 	assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
66 	assert(system("mknod /tmp/test_dev_cgroup_zero c 1 5") == 0);
67 	assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
68 
69 	assert(system("dd if=/dev/urandom of=/dev/zero count=64") == 0);
70 
71 	/* src is allowed, target is forbidden */
72 	assert(system("dd if=/dev/urandom of=/dev/full count=64"));
73 
74 	/* src is forbidden, target is allowed */
75 	assert(system("dd if=/dev/random of=/dev/zero count=64"));
76 
77 	error = 0;
78 	printf("test_dev_cgroup:PASS\n");
79 
80 err:
81 	cleanup_cgroup_environment();
82 
83 out:
84 	return error;
85 }
86