1 files changed, 152 insertions, 0 deletions
diff --git a/tools/testing/selftests/firmware/fw_namespace.c b/tools/testing/selftests/firmware/fw_namespace.c
new file mode 100644
index 000000000..4c6f0cd83
--- /dev/null
+++ b/tools/testing/selftests/firmware/fw_namespace.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Test triggering of loading of firmware from different mount
+ * namespaces. Expect firmware to be always loaded from the mount
+ * namespace of PID 1. */
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#ifndef CLONE_NEWNS
+# define CLONE_NEWNS 0x00020000
+#endif
+
+static char *fw_path = NULL;
+
+static void die(char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	if (fw_path)
+		unlink(fw_path);
+	umount("/lib/firmware");
+	exit(EXIT_FAILURE);
+}
+
+static void trigger_fw(const char *fw_name, const char *sys_path)
+{
+	int fd;
+
+	fd = open(sys_path, O_WRONLY);
+	if (fd < 0)
+		die("open failed: %s\n",
+		    strerror(errno));
+	if (write(fd, fw_name, strlen(fw_name)) != strlen(fw_name))
+		exit(EXIT_FAILURE);
+	close(fd);
+}
+
+static void setup_fw(const char *fw_path)
+{
+	int fd;
+	const char fw[] = "ABCD0123";
+
+	fd = open(fw_path, O_WRONLY | O_CREAT, 0600);
+	if (fd < 0)
+		die("open failed: %s\n",
+		    strerror(errno));
+	if (write(fd, fw, sizeof(fw) -1) != sizeof(fw) -1)
+		die("write failed: %s\n",
+		    strerror(errno));
+	close(fd);
+}
+
+static bool test_fw_in_ns(const char *fw_name, const char *sys_path, bool block_fw_in_parent_ns)
+{
+	pid_t child;
+
+	if (block_fw_in_parent_ns)
+		if (mount("test", "/lib/firmware", "tmpfs", MS_RDONLY, NULL) == -1)
+			die("blocking firmware in parent ns failed\n");
+
+	child = fork();
+	if (child == -1) {
+		die("fork failed: %s\n",
+			strerror(errno));
+	}
+	if (child != 0) { /* parent */
+		pid_t pid;
+		int status;
+
+		pid = waitpid(child, &status, 0);
+		if (pid == -1) {
+			die("waitpid failed: %s\n",
+				strerror(errno));
+		}
+		if (pid != child) {
+			die("waited for %d got %d\n",
+				child, pid);
+		}
+		if (!WIFEXITED(status)) {
+			die("child did not terminate cleanly\n");
+		}
+		if (block_fw_in_parent_ns)
+			umount("/lib/firmware");
+		return WEXITSTATUS(status) == EXIT_SUCCESS;
+	}
+
+	if (unshare(CLONE_NEWNS) != 0) {
+		die("unshare(CLONE_NEWNS) failed: %s\n",
+			strerror(errno));
+	}
+	if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) == -1)
+		die("remount root in child ns failed\n");
+
+	if (!block_fw_in_parent_ns) {
+		if (mount("test", "/lib/firmware", "tmpfs", MS_RDONLY, NULL) == -1)
+			die("blocking firmware in child ns failed\n");
+	} else
+		umount("/lib/firmware");
+
+	trigger_fw(fw_name, sys_path);
+
+	exit(EXIT_SUCCESS);
+}
+
+int main(int argc, char **argv)
+{
+	const char *fw_name = "test-firmware.bin";
+	char *sys_path;
+	if (argc != 2)
+		die("usage: %s sys_path\n", argv[0]);
+
+	/* Mount tmpfs to /lib/firmware so we don't have to assume
+	   that it is writable for us.*/
+	if (mount("test", "/lib/firmware", "tmpfs", 0, NULL) == -1)
+		die("mounting tmpfs to /lib/firmware failed\n");
+
+	sys_path = argv[1];
+	if (asprintf(&fw_path, "/lib/firmware/%s", fw_name) < 0)
+		die("error: failed to build full fw_path\n");
+
+	setup_fw(fw_path);
+
+	setvbuf(stdout, NULL, _IONBF, 0);
+	/* Positive case: firmware in PID1 mount namespace */
+	printf("Testing with firmware in parent namespace (assumed to be same file system as PID1)\n");
+	if (!test_fw_in_ns(fw_name, sys_path, false))
+		die("error: failed to access firmware\n");
+
+	/* Negative case: firmware in child mount namespace, expected to fail */
+	printf("Testing with firmware in child namespace\n");
+	if (test_fw_in_ns(fw_name, sys_path, true))
+		die("error: firmware access did not fail\n");
+
+	unlink(fw_path);
+	free(fw_path);
+	umount("/lib/firmware");
+	exit(EXIT_SUCCESS);
+}