Introduce Invincible Mode: Self recover service

jni/daemon/bootstages.c

@@ -399,7 +399,45 @@ static void simple_mount(const char *path) {
  * Miscellaneous *
  *****************/
 
-static void mount_mirrors() {
+// A one time setup
+void daemon_init() {
+	LOGI("* Creating /sbin overlay");
+	DIR *dir;
+	struct dirent *entry;
+	int root, sbin;
+	char target[PATH_MAX], linkpath[PATH_MAX];
+	// Setup links under /sbin
+	xmount(NULL, "/", NULL, MS_REMOUNT, NULL);
+	xmkdir("/root", 0755);
+	xchmod("/root", 0755);
+	root = xopen("/root", O_RDONLY | O_CLOEXEC);
+	sbin = xopen("/sbin", O_RDONLY | O_CLOEXEC);
+	dir = fdopendir(sbin);
+	while((entry = readdir(dir))) {
+		if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) continue;
+		linkat(sbin, entry->d_name, root, entry->d_name, 0);
+		if (strcmp(entry->d_name, "magisk") == 0)
+			unlinkat(sbin, entry->d_name, 0);
+	}
+	close(sbin);
+	mount("tmpfs", "/sbin", "tmpfs", 0, NULL);
+	sbin = xopen("/sbin", O_RDONLY | O_CLOEXEC);
+	fchmod(sbin, 0755);
+	fsetfilecon(sbin, "u:object_r:rootfs:s0");
+	dir = fdopendir(root);
+	while((entry = readdir(dir))) {
+		if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) continue;
+		snprintf(target, sizeof(target), "/root/%s", entry->d_name);
+		snprintf(linkpath, sizeof(linkpath), "/sbin/%s", entry->d_name);
+		symlink(target, linkpath);
+	}
+	for (int i = 0; applet[i]; ++i) {
+		snprintf(linkpath, sizeof(linkpath), "/sbin/%s", applet[i]);
+		symlink("/root/magisk", linkpath);
+	}
+	xmkdir("/magisk", 0755);
+	xmount(NULL, "/", NULL, MS_REMOUNT | MS_RDONLY, NULL);
+
 	LOGI("* Mounting mirrors");
 	struct vector mounts;
 	vec_init(&mounts);
@@ -451,9 +489,8 @@ static void mount_mirrors() {
 	}
 	mkdir_p(MIRRDIR "/bin", 0755);
 	bind_mount(DATABIN, MIRRDIR "/bin");
-}
 
-static void link_busybox() {
+	LOGI("* Setting up internal busybox");
 	mkdir_p(BBPATH, 0755);
 	exec_command_sync(MIRRDIR "/bin/busybox", "--install", "-s", BBPATH, NULL);
 	symlink(MIRRDIR "/bin/busybox", BBPATH "/busybox");
@@ -595,9 +632,8 @@ void post_fs_data(int client) {
 		exec_command_sync("sh", "-c", "mv /data/magisk/stock_boot* /data", NULL);
 	}
 
-	// Link busybox
+	// Initialize
-	mount_mirrors();
+	daemon_init();
-	link_busybox();
 
 	// Merge images
 	if (merge_img("/data/magisk_merge.img", MAINIMG)) {

jni/daemon/daemon.c

@@ -114,25 +114,7 @@ static void *large_sepol_patch(void *args) {
 	return NULL;
 }
 
-void start_daemon(int client) {
+void start_daemon() {
-	// Launch the daemon, create new session, set proper context
-	if (getuid() != UID_ROOT || getgid() != UID_ROOT) {
-		fprintf(stderr, "Starting daemon requires root: %s\n", strerror(errno));
-		PLOGE("start daemon");
-	}
-
-	switch (fork()) {
-	case -1:
-		PLOGE("fork");
-	case 0:
-		break;
-	default:
-		return;
-	}
-
-	// First close the client, it's useless for us
-	close(client);
-	xsetsid();
 	setcon("u:r:su:s0");
 	umask(0);
 	int fd = xopen("/dev/null", O_RDWR | O_CLOEXEC);
@@ -166,13 +148,6 @@ void start_daemon(int client) {
 	// Unlock all blocks for rw
 	unlock_blocks();
 
-	// Setup links under /sbin
-	xmount(NULL, "/", NULL, MS_REMOUNT, NULL);
-	create_links(NULL, "/sbin");
-	xchmod("/sbin", 0755);
-	xmkdir("/magisk", 0755);
-	xmount(NULL, "/", NULL, MS_REMOUNT | MS_RDONLY, NULL);
-
 	// Loop forever to listen for requests
 	while(1) {
 		int *client = xmalloc(sizeof(int));
@@ -189,11 +164,26 @@ int connect_daemon() {
 	struct sockaddr_un sun;
 	int fd = setup_socket(&sun);
 	if (connect(fd, (struct sockaddr*) &sun, sizeof(sun))) {
-		/* If we cannot access the daemon, we start the daemon
+		// If we cannot access the daemon, we start a daemon in the child process if possible
-		 * since there is no clear entry point when the daemon should be started
+
-		 */
+		if (getuid() != UID_ROOT || getgid() != UID_ROOT) {
-		LOGD("client: connect fail, try launching new daemon process\n");
+			fprintf(stderr, "Starting daemon requires root: %s\n", strerror(errno));
-		start_daemon(fd);
+			PLOGE("start daemon");
+		}
+
+		switch (fork()) {
+		case -1:
+			PLOGE("fork");
+		case 0:
+			LOGD("client: connect fail, try launching new daemon process\n");
+			close(fd);
+			xsetsid();
+			start_daemon();
+			break;
+		default:
+			break;
+		}
+
 		do {
 			// Wait for 10ms
 			usleep(10);

jni/daemon/magisk.c

@@ -54,11 +54,11 @@ static void usage() {
 		"   --resizeimg IMG SIZE      resize ext4 image. SIZE is interpreted in MB\n"
 		"   --mountimg IMG PATH       mount IMG to PATH and prints the loop device\n"
 		"   --umountimg PATH LOOP     unmount PATH and delete LOOP device\n"
-		"   --[boot stage]            start boot stage service\n"
+		"   --[init service]          start init service\n"
 		"   --unlock-blocks           set BLKROSET flag to OFF for all block devices\n"
 		"\n"
-		"Supported boot stages:\n"
+		"Supported init services:\n"
-		"   post-fs, post-fs-data, service\n"
+		"   daemon post-fs, post-fs-data, service\n"
 		"\n"
 		"Supported applets:\n"
 	, argv0, argv0);
@@ -146,6 +146,9 @@ int main(int argc, char *argv[]) {
 		} else if (strcmp(argv[1], "--unlock-blocks") == 0) {
 			unlock_blocks();
 			return 0;
+		} else if (strcmp(argv[1], "--daemon") == 0) {
+			// Start daemon, this process won't return
+			start_daemon();
 		} else if (strcmp(argv[1], "--post-fs") == 0) {
 			int fd = connect_daemon();
 			write_int(fd, POST_FS);

jni/include/daemon.h

@@ -38,7 +38,7 @@ typedef enum {
 
 // daemon.c
 
-void start_daemon(int client);
+void start_daemon();
 int connect_daemon();
 
 // socket_trans.c

jni/magiskhide/hide_utils.c

@@ -69,42 +69,6 @@ void clean_magisk_props() {
 	getprop_all(rm_magisk_prop);
 }
 
-void relink_sbin() {
-	struct stat st;
-	if (stat("/sbin_orig", &st) == -1 && errno == ENOENT) {
-		// Re-link all binaries and bind mount
-		DIR *dir;
-		struct dirent *entry;
-		char from[PATH_MAX], to[PATH_MAX];
-
-		LOGI("hide_utils: Re-linking /sbin\n");
-
-		xmount(NULL, "/", NULL, MS_REMOUNT, NULL);
-		xrename("/sbin", "/sbin_orig");
-		xmkdir("/sbin", 0755);
-		xchmod("/sbin", 0755);
-		xmount(NULL, "/", NULL, MS_REMOUNT | MS_RDONLY, NULL);
-		xmkdir("/dev/sbin_bind", 0755);
-		xchmod("/dev/sbin_bind", 0755);
-		dir = xopendir("/sbin_orig");
-
-		while ((entry = xreaddir(dir))) {
-			if (strcmp(entry->d_name, "..") == 0)
-				continue;
-			snprintf(from, sizeof(from), "/sbin_orig/%s", entry->d_name);
-			if (entry->d_type == DT_LNK)
-				xreadlink(from, from, sizeof(from));
-			snprintf(to, sizeof(to), "/dev/sbin_bind/%s", entry->d_name);
-			symlink(from, to);
-			lsetfilecon(to, "u:object_r:rootfs:s0");
-		}
-
-		closedir(dir);
-
-		xmount("/dev/sbin_bind", "/sbin", NULL, MS_BIND, NULL);
-	}
-}
-
 int add_list(char *proc) {
 	if (!hideEnabled) {
 		free(proc);

jni/magiskhide/magiskhide.h

@@ -12,7 +12,6 @@ void proc_monitor();
 // Utility functions
 void manage_selinux();
 void hide_sensitive_props();
-void relink_sbin();
 void clean_magisk_props();
 
 // List managements

jni/magiskhide/proc_monitor.c

@@ -90,7 +90,6 @@ static void hide_daemon(int pid) {
 	struct vector mount_list;
 
 	manage_selinux();
-	relink_sbin();
 	clean_magisk_props();
 
 	if (switch_mnt_ns(pid))

jni/utils/img.c

@@ -51,20 +51,13 @@ static char *loopsetup(const char *img) {
 int create_img(const char *img, int size) {
 	unlink(img);
 	LOGI("Create %s with size %dM\n", img, size);
-	// Create a temp file with the file contexts
+	int ret;
-	char file_contexts[] = "/magisk(/.*)? u:object_r:system_file:s0\n";
-	// If not root, attempt to create in current diretory
-	char *filename = getuid() == UID_ROOT ? "/dev/file_contexts_image" : "file_contexts_image";
-	int ret, fd = xopen(filename, O_WRONLY | O_CREAT | O_TRUNC, 0644);
-	xwrite(fd, file_contexts, sizeof(file_contexts));
-	close(fd);
 
 	char buffer[16];
 	snprintf(buffer, sizeof(buffer), "%dM", size);
-	ret = exec_command_sync("make_ext4fs", "-l", buffer, "-a", "/magisk", "-S", filename, img, NULL);
+	ret = exec_command_sync("make_ext4fs", "-l", buffer, img, NULL);
 	if (ret < 0)
 		return 1;
-	unlink(filename);
 	return ret;
 }
 

jni/utils/misc.c

@@ -167,32 +167,25 @@ void ps_filter_proc_name(const char *pattern, void (*func)(int)) {
 	ps(proc_name_filter);
 }
 
-#define DEV_BLOCK "/dev/block"
-
 void unlock_blocks() {
-	char path[PATH_MAX];
 	DIR *dir;
 	struct dirent *entry;
-	int fd, OFF = 0;
+	int fd, dev, OFF = 0;
 
-	if (!(dir = xopendir(DEV_BLOCK)))
+	if ((dev = xopen("/dev/block", O_RDONLY | O_CLOEXEC)) < 0)
 		return;
+	dir = fdopendir(dev);
 
 	while((entry = readdir(dir))) {
-		if (entry->d_type == DT_BLK &&
+		if (entry->d_type == DT_BLK) {
-			strstr(entry->d_name, "ram") == NULL &&
+			if ((fd = openat(dev, entry->d_name, O_RDONLY)) < 0)
-			strstr(entry->d_name, "loop") == NULL) {
-			snprintf(path, sizeof(path), "%s/%s", DEV_BLOCK, entry->d_name);
-			if ((fd = xopen(path, O_RDONLY)) < 0)
 				continue;
-
 			if (ioctl(fd, BLKROSET, &OFF) == -1)
-				PLOGE("unlock %s", path);
+				PLOGE("unlock %s", entry->d_name);
 			close(fd);
 		}
 	}
-
+	close(dev);
-	closedir(dir);
 }
 
 void setup_sighandlers(void (*handler)(int)) {

scripts/init.magisk.rc

@@ -2,20 +2,24 @@
 
 on post-fs
     start logd
+    start magisk_daemon
+    wait /dev/.magisk.unblock 1
     start magisk_pfs
-    wait /dev/.magisk.unblock 20
+    wait /dev/.magisk.unblock 5
 
 on post-fs-data
     rm /dev/.magisk.unblock
     load_persist_props
     start magisk_pfsd
-    wait /dev/.magisk.unblock 60
+    wait /dev/.magisk.unblock 10
-
-on property:magisk.restart_pfsd=1
-    trigger post-fs-data
 
 # Services
 
+# Self recoverable service
+service magisk_daemon /sbin/magisk --daemon
+    user root
+    seclabel u:r:su:s0
+
 # launch post-fs script
 service magisk_pfs /sbin/magisk --post-fs
     user root