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(fmt: "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(fmt: "open failed: %s\n",
56 strerror(errno));
57 if (write(fd, fw, sizeof(fw) -1) != sizeof(fw) -1)
58 die(fmt: "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(fmt: "blocking firmware in parent ns failed\n");
70
71 child = fork();
72 if (child == -1) {
73 die(fmt: "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(fmt: "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(fmt: "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(fmt: "unshare(CLONE_NEWNS) failed: %s\n",
99 strerror(errno));
100 }
101 if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) == -1)
102 die(fmt: "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(fmt: "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(fmt: "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(fmt: "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(fmt: "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(fmt: "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(fmt: "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

source code of linux/tools/testing/selftests/firmware/fw_namespace.c