Add zygote server notifier

native/jni/core/applets.cpp

@@ -11,13 +11,15 @@
 static int (*applet_main[]) (int, char *[]) =
 		{ magisk_main, su_client_main, resetprop_main, magiskhide_main, nullptr };
 
-__attribute__((noreturn)) static void call_applets(int argc, char *argv[]) {
+[[noreturn]] static void call_applets(int argc, char *argv[]) {
 	// Applets
 	for (int i = 0; applet_names[i]; ++i) {
 		if (strcmp(basename(argv[0]), applet_names[i]) == 0) {
 			exit((*applet_main[i])(argc, argv));
 		}
 	}
+	if (strncmp(basename(argv[0]), "app_process", 11) == 0)
+		exit(app_process_main(argc, argv));
 	fprintf(stderr, "%s: applet not found\n", argv[0]);
 	exit(1);
 }

native/jni/core/bootstages.cpp

@@ -575,11 +575,30 @@ static void dump_logs() {
 	pthread_exit(nullptr);
 }
 
-[[noreturn]] static inline void core_only() {
+[[noreturn]] static void core_only() {
 	auto_start_magiskhide();
+	cp_afc("/sbin/magisk", MAGISKTMP "/app_process");
+	struct stat st;
+	for (const char *app : { "app_process", "app_process32", "app_process64" }) {
+		sprintf(buf, "/system/bin/%s", app);
+		if (lstat(buf, &st) == 0 && S_ISREG(st.st_mode)) {
+			clone_attr(buf, MAGISKTMP "/app_process");
+			bind_mount(MAGISKTMP "/app_process", buf);
+		}
+	}
 	unblock_boot_process();
 }
 
+void zygote_notify(int client, struct ucred *cred) {
+	/* TODO: notify services that need zygote PIDs */
+	char *path = read_string(client);
+	LOGD("%s PID=[%d]\n", path, cred->pid);
+	close(client);
+	usleep(100000);
+	bind_mount(MAGISKTMP "/app_process", path);
+	free(path);
+}
+
 void post_fs_data(int client) {
 	// ack
 	write_int(client, 0);

native/jni/core/daemon.cpp

@@ -88,7 +88,9 @@ static void *request_handler(void *args) {
 		break;
 	case SQLITE_CMD:
 		exec_sql(client);
-		close(client);
+		break;
+	case ZYGOTE_NOTIFY:
+		zygote_notify(client, &credential);
 		break;
 	default:
 		close(client);
@@ -161,13 +163,13 @@ int switch_mnt_ns(int pid) {
 	return ret;
 }
 
-int connect_daemon() {
+int connect_daemon(bool create) {
 	struct sockaddr_un sun;
 	socklen_t len = setup_sockaddr(&sun, MAIN_SOCKET);
 	int fd = xsocket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
 	if (connect(fd, (struct sockaddr*) &sun, len)) {
-		if (getuid() != UID_ROOT || getgid() != UID_ROOT) {
+		if (!create || getuid() != UID_ROOT || getgid() != UID_ROOT) {
-			fprintf(stderr, "No daemon is currently running!\n");
+			LOGE("No daemon is currently running!\n");
 			exit(1);
 		}
 

native/jni/core/db.cpp

@@ -320,4 +320,5 @@ void exec_sql(int client) {
 		return;
 	);
 	write_int(client, 0);
+	close(client);
 }

native/jni/core/magisk.cpp

@@ -1,3 +1,4 @@
+#include <sys/mount.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -81,19 +82,19 @@ int magisk_main(int argc, char *argv[]) {
 		cp_afc(argv[2], argv[3]);
 		return 0;
 	} else if (strcmp(argv[1], "--daemon") == 0) {
-		int fd = connect_daemon();
+		int fd = connect_daemon(true);
 		write_int(fd, DO_NOTHING);
 		return 0;
 	} else if (strcmp(argv[1], "--post-fs-data") == 0) {
-		int fd = connect_daemon();
+		int fd = connect_daemon(true);
 		write_int(fd, POST_FS_DATA);
 		return read_int(fd);
 	} else if (strcmp(argv[1], "--service") == 0) {
-		int fd = connect_daemon();
+		int fd = connect_daemon(true);
 		write_int(fd, LATE_START);
 		return read_int(fd);
 	} else if (strcmp(argv[1], "--boot-complete") == 0) {
-		int fd = connect_daemon();
+		int fd = connect_daemon(true);
 		write_int(fd, BOOT_COMPLETE);
 		return read_int(fd);
 	} else if (strcmp(argv[1], "--sqlite") == 0) {
@@ -111,3 +112,29 @@ int magisk_main(int argc, char *argv[]) {
 #endif
 	usage();
 }
+
+int app_process_main(int argc, char *argv[]) {
+	char path[512];
+	bool zygote = false;
+	for (int i = 0; i < argc; ++i) {
+		if (strcmp(argv[i], "--zygote") == 0) {
+			zygote = true;
+			break;
+		}
+	}
+	if (zygote) {
+		// Notify main daemon
+		sprintf(path, "/system/bin/%s", basename(argv[0]));
+		umount2(path, MNT_DETACH);
+		int fd = connect_daemon();
+		write_int(fd, ZYGOTE_NOTIFY);
+		write_string(fd, path);
+		close(fd);
+	} else {
+		// Redirect to system mirror
+		sprintf(path, MIRRDIR "/system/bin/%s", basename(argv[0]));
+	}
+	argv[0] = path;
+	execve(path, argv, environ);
+	return -1;
+}

native/jni/include/daemon.h

@@ -21,6 +21,7 @@ enum {
 	BOOT_COMPLETE,
 	MAGISKHIDE,
 	SQLITE_CMD,
+	ZYGOTE_NOTIFY,
 };
 
 // Return codes for daemon
@@ -33,7 +34,7 @@ enum {
 
 // daemon.c
 
-int connect_daemon();
+int connect_daemon(bool create = false);
 int switch_mnt_ns(int pid);
 
 // socket.c
@@ -60,6 +61,7 @@ void write_key_token(int fd, const char *key, int tok);
  ***************/
 
 void unlock_blocks();
+void zygote_notify(int client, struct ucred *cred);
 void post_fs_data(int client);
 void late_start(int client);
 void boot_complete(int client);

native/jni/include/magisk.h

@@ -41,8 +41,8 @@
 
 extern int SDK_INT;
 
-#define applet_names ((const char *[]) { "magisk", "su", "resetprop", "magiskhide", nullptr })
+constexpr const char *applet_names[] = { "magisk", "su", "resetprop", "magiskhide", nullptr };
-#define init_applet  ((const char *[]) { "magiskpolicy", "supolicy", nullptr })
+constexpr const char *init_applet[] = { "magiskpolicy", "supolicy", nullptr };
 
 // Multi-call entrypoints
 int magisk_main(int argc, char *argv[]);
@@ -50,5 +50,6 @@ int magiskhide_main(int argc, char *argv[]);
 int magiskpolicy_main(int argc, char *argv[]);
 int su_client_main(int argc, char *argv[]);
 int resetprop_main(int argc, char *argv[]);
+int app_process_main(int argc, char *argv[]);
 
 #endif

native/jni/magiskpolicy/rules.cpp

@@ -78,6 +78,7 @@ void sepol_magisk_rules() {
 	allowSuClient("untrusted_app_25");
 	allowSuClient("untrusted_app_27");
 	allowSuClient("update_engine");
+	allowSuClient("zygote");
 
 	// suRights
 	sepol_allow("servicemanager", SEPOL_PROC_DOMAIN, "dir", "search");