1// SPDX-License-Identifier: GPL-2.0
2/* Test triggering of loading of firmware from different mount
3 * namespaces. Expect firmware to be always loaded from the mount
4 * namespace of PID 1. */
5#define _GNU_SOURCE
6#include <errno.h>
7#include <fcntl.h>
8#include <sched.h>
9#include <stdarg.h>
10#include <stdbool.h>
11#include <stdio.h>
12#include <stdlib.h>
13#include <string.h>
14#include <sys/mount.h>
15#include <sys/stat.h>
16#include <sys/types.h>
17#include <sys/wait.h>
18#include <unistd.h>
19
20#ifndef CLONE_NEWNS
21# define CLONE_NEWNS 0x00020000
22#endif
23
24static char *fw_path = NULL;
25
26static void die(char *fmt, ...)
27{
28	va_list ap;
29
30	va_start(ap, fmt);
31	vfprintf(stderr, fmt, ap);
32	va_end(ap);
33	if (fw_path)
34		unlink(fw_path);
35	umount("/lib/firmware");
36	exit(EXIT_FAILURE);
37}
38
39static void trigger_fw(const char *fw_name, const char *sys_path)
40{
41	int fd;
42
43	fd = open(sys_path, O_WRONLY);
44	if (fd < 0)
45		die("open failed: %s\n",
46		    strerror(errno));
47	if (write(fd, fw_name, strlen(fw_name)) != strlen(fw_name))
48		exit(EXIT_FAILURE);
49	close(fd);
50}
51
52static void setup_fw(const char *fw_path)
53{
54	int fd;
55	const char fw[] = "ABCD0123";
56
57	fd = open(fw_path, O_WRONLY | O_CREAT, 0600);
58	if (fd < 0)
59		die("open failed: %s\n",
60		    strerror(errno));
61	if (write(fd, fw, sizeof(fw) -1) != sizeof(fw) -1)
62		die("write failed: %s\n",
63		    strerror(errno));
64	close(fd);
65}
66
67static bool test_fw_in_ns(const char *fw_name, const char *sys_path, bool block_fw_in_parent_ns)
68{
69	pid_t child;
70
71	if (block_fw_in_parent_ns)
72		if (mount("test", "/lib/firmware", "tmpfs", MS_RDONLY, NULL) == -1)
73			die("blocking firmware in parent ns failed\n");
74
75	child = fork();
76	if (child == -1) {
77		die("fork failed: %s\n",
78			strerror(errno));
79	}
80	if (child != 0) { /* parent */
81		pid_t pid;
82		int status;
83
84		pid = waitpid(child, &status, 0);
85		if (pid == -1) {
86			die("waitpid failed: %s\n",
87				strerror(errno));
88		}
89		if (pid != child) {
90			die("waited for %d got %d\n",
91				child, pid);
92		}
93		if (!WIFEXITED(status)) {
94			die("child did not terminate cleanly\n");
95		}
96		if (block_fw_in_parent_ns)
97			umount("/lib/firmware");
98		return WEXITSTATUS(status) == EXIT_SUCCESS ? true : false;
99	}
100
101	if (unshare(CLONE_NEWNS) != 0) {
102		die("unshare(CLONE_NEWNS) failed: %s\n",
103			strerror(errno));
104	}
105	if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) == -1)
106		die("remount root in child ns failed\n");
107
108	if (!block_fw_in_parent_ns) {
109		if (mount("test", "/lib/firmware", "tmpfs", MS_RDONLY, NULL) == -1)
110			die("blocking firmware in child ns failed\n");
111	} else
112		umount("/lib/firmware");
113
114	trigger_fw(fw_name, sys_path);
115
116	exit(EXIT_SUCCESS);
117}
118
119int main(int argc, char **argv)
120{
121	const char *fw_name = "test-firmware.bin";
122	char *sys_path;
123	if (argc != 2)
124		die("usage: %s sys_path\n", argv[0]);
125
126	/* Mount tmpfs to /lib/firmware so we don't have to assume
127	   that it is writable for us.*/
128	if (mount("test", "/lib/firmware", "tmpfs", 0, NULL) == -1)
129		die("mounting tmpfs to /lib/firmware failed\n");
130
131	sys_path = argv[1];
132	if (asprintf(&fw_path, "/lib/firmware/%s", fw_name) < 0)
133		die("error: failed to build full fw_path\n");
134
135	setup_fw(fw_path);
136
137	setvbuf(stdout, NULL, _IONBF, 0);
138	/* Positive case: firmware in PID1 mount namespace */
139	printf("Testing with firmware in parent namespace (assumed to be same file system as PID1)\n");
140	if (!test_fw_in_ns(fw_name, sys_path, false))
141		die("error: failed to access firmware\n");
142
143	/* Negative case: firmware in child mount namespace, expected to fail */
144	printf("Testing with firmware in child namespace\n");
145	if (test_fw_in_ns(fw_name, sys_path, true))
146		die("error: firmware access did not fail\n");
147
148	unlink(fw_path);
149	free(fw_path);
150	umount("/lib/firmware");
151	exit(EXIT_SUCCESS);
152}
153