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}