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 
24 static char *fw_path = NULL;
25 
26 static 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 
39 static 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 
52 static 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 
67 static 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;
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 
119 int 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