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;
 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}