Support Safe Mode detection

When detecting device is booting as Safe Mode, disable all modules and
MagiskHide and skip all operations. The only thing that'll be available
in this state is root (Magisk Manager will also be disabled by system).

Since the next normal boot will also have all modules disabled, this can
be used to rescue a device in the case when a rogue module causes
bootloop and no custom recovery is available (or recoveries without
the ability to decrypt data).

build.py

@@ -299,7 +299,7 @@ def build_binary(args):
 
     header('* Building binaries: ' + ' '.join(args.target))
 
-    os.utime(op.join('native', 'jni', 'include', 'flags.h'))
+    # os.utime(op.join('native', 'jni', 'include', 'flags.h'))
 
     # Basic flags
     global base_flags

native/jni/core/bootstages.cpp

@@ -21,6 +21,7 @@ using namespace std;
 
 static bool no_secure_dir = false;
 static bool pfs_done = false;
+static bool safe_mode = false;
 
 /*********
  * Setup *
@@ -224,12 +225,6 @@ static void dump_logs() {
 	pthread_exit(nullptr);
 }
 
-[[noreturn]] static void core_only() {
-	pfs_done = true;
-	auto_start_magiskhide();
-	unblock_boot_process();
-}
-
 void post_fs_data(int client) {
 	// ack
 	write_int(client, 0);
@@ -262,16 +257,21 @@ void post_fs_data(int client) {
 		unblock_boot_process();
 	}
 
+	if (getprop("persist.sys.safemode", true) == "1") {
+		safe_mode = true;
+		// Disable all modules and magiskhide so next boot will be clean
+		foreach_modules("disable");
+		stop_magiskhide();
+	} else {
 		LOGI("* Running post-fs-data.d scripts\n");
 		exec_common_script("post-fs-data");
-
-	// Core only mode
-	if (access(DISABLEFILE, F_OK) == 0)
-		core_only();
-
 		handle_modules();
+		auto_start_magiskhide();
+	}
 
-	core_only();
+	// We still want to do magic mount because root itself might need it
+	magic_mount();
+	unblock_boot_process();
 }
 
 void late_start(int client) {
@@ -290,7 +290,7 @@ void late_start(int client) {
 		reboot();
 	}
 
-	if (!pfs_done)
+	if (!pfs_done || safe_mode)
 		return;
 
 	auto_start_magiskhide();
@@ -298,11 +298,8 @@ void late_start(int client) {
 	LOGI("* Running service.d scripts\n");
 	exec_common_script("service");
 
-	// Core only mode
-	if (access(DISABLEFILE, F_OK) != 0) {
 	LOGI("* Running module service scripts\n");
 	exec_module_script("service", module_list);
-	}
 
 	// All boot stage done, cleanup
 	module_list.clear();
@@ -315,7 +312,7 @@ void boot_complete(int client) {
 	write_int(client, 0);
 	close(client);
 
-	if (!pfs_done)
+	if (!pfs_done || safe_mode)
 		return;
 
 	auto_start_magiskhide();

native/jni/core/daemon.cpp

@@ -96,9 +96,10 @@ static void *request_handler(void *args) {
 		exec_sql(client);
 		break;
 	case REMOVE_MODULES:
-		remove_modules();
+		foreach_modules("remove");
 		write_int(client, 0);
 		close(client);
+		reboot();
 		break;
 	case GET_PATH:
 		write_string(client, MAGISKTMP.data());

native/jni/core/module.cpp

@@ -542,7 +542,7 @@ static void inject_magisk_bins(root_node *system) {
 		delete bin->extract(init_applet[i]);
 }
 
-static void mount_modules() {
+void magic_mount() {
 	node_entry::mirror_dir = MAGISKTMP + "/" MIRRDIR;
 	node_entry::module_mnt = MAGISKTMP + "/" MODULEMNT "/";
 
@@ -683,12 +683,10 @@ void handle_modules() {
 	// Recollect modules (module scripts could remove itself)
 	module_list.clear();
 	collect_modules();
-
-	mount_modules();
 }
 
-void remove_modules() {
-	LOGI("* Remove all modules and reboot\n");
+void foreach_modules(const char *name) {
+	LOGI("* Add %s to all modules\n", name);
 	auto dir = open_dir(MODULEROOT);
 	if (!dir)
 		return;
@@ -700,9 +698,8 @@ void remove_modules() {
 				continue;
 
 			int modfd = xopenat(dfd, entry->d_name, O_RDONLY | O_CLOEXEC);
-			close(xopenat(modfd, "remove", O_RDONLY | O_CREAT | O_CLOEXEC, 0));
+			close(xopenat(modfd, name, O_RDONLY | O_CREAT | O_CLOEXEC, 0));
 			close(modfd);
 		}
 	}
-	reboot();
 }

native/jni/include/daemon.hpp

@@ -40,15 +40,19 @@ void late_start(int client);
 void boot_complete(int client);
 void magiskhide_handler(int client);
 void su_daemon_handler(int client, struct ucred *credential);
-void remove_modules();
+void foreach_modules(const char *name);
 
 // Misc
 int connect_daemon(bool create = false);
-void auto_start_magiskhide();
 void unlock_blocks();
 void handle_modules();
+void magic_mount();
 void reboot();
 
+// MagiskHide
+void auto_start_magiskhide();
+int stop_magiskhide();
+
 // Scripting
 void exec_script(const char *script);
 void exec_common_script(const char *stage);

native/jni/include/magisk.hpp

@@ -7,7 +7,6 @@
 #define JAVA_PACKAGE_NAME "com.topjohnwu.magisk"
 #define LOGFILE         "/cache/magisk.log"
 #define UNBLOCKFILE     "/dev/.magisk_unblock"
-#define DISABLEFILE     "/cache/.disable_magisk"
 #define SECURE_DIR      "/data/adb"
 #define MODULEROOT      SECURE_DIR "/modules"
 #define MODULEUPGRADE   SECURE_DIR "/modules_update"

native/jni/magiskhide/hide_utils.cpp

@@ -10,7 +10,6 @@
 #include <magisk.hpp>
 #include <utils.hpp>
 #include <db.hpp>
-#include <daemon.hpp>
 
 #include "magiskhide.hpp"
 
@@ -267,9 +266,11 @@ void launch_magiskhide(int client) {
 int stop_magiskhide() {
 	LOGI("* Stopping MagiskHide\n");
 
+	if (hide_enabled)
+		pthread_kill(proc_monitor_thread, SIGTERMTHRD);
+
 	hide_enabled = false;
 	set_hide_config();
-	pthread_kill(proc_monitor_thread, SIGTERMTHRD);
 
 	return DAEMON_SUCCESS;
 }