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
die(char * fmt,...)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
trigger_fw(const char * fw_name,const char * sys_path)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
setup_fw(const char * fw_path)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
test_fw_in_ns(const char * fw_name,const char * sys_path,bool block_fw_in_parent_ns)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 ? 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
main(int argc,char ** argv)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 asprintf(&fw_path, "/lib/firmware/%s", fw_name);
133
134 setup_fw(fw_path);
135
136 setvbuf(stdout, NULL, _IONBF, 0);
137 /* Positive case: firmware in PID1 mount namespace */
138 printf("Testing with firmware in parent namespace (assumed to be same file system as PID1)\n");
139 if (!test_fw_in_ns(fw_name, sys_path, false))
140 die("error: failed to access firmware\n");
141
142 /* Negative case: firmware in child mount namespace, expected to fail */
143 printf("Testing with firmware in child namespace\n");
144 if (test_fw_in_ns(fw_name, sys_path, true))
145 die("error: firmware access did not fail\n");
146
147 unlink(fw_path);
148 free(fw_path);
149 umount("/lib/firmware");
150 exit(EXIT_SUCCESS);
151 }
152
