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