Obfuscate socket name to prevent detection

Because why not

native/jni/core/magiskinit.c

@@ -56,6 +56,8 @@
 extern policydb_t *policydb;
 int (*init_applet_main[]) (int, char *[]) = { magiskpolicy_main, magiskpolicy_main, NULL };
 static int keepverity = 0, keepencrypt = 0;
+static char RAND_SOCKET_NAME[sizeof(SOCKET_NAME)];
+static int SOCKET_OFF = -1;
 
 struct cmdline {
 	int skip_initramfs;
@@ -367,6 +369,23 @@ static int dump_magiskrc(const char *path, mode_t mode) {
 	return 0;
 }
 
+static void patch_socket_name(const char *path) {
+	void *buf;
+	size_t size;
+	mmap_rw(path, &buf, &size);
+	if (SOCKET_OFF < 0) {
+		for (int i = 0; i < size; ++i) {
+			if (memcmp(buf + i, SOCKET_NAME, sizeof(SOCKET_NAME)) == 0) {
+				SOCKET_OFF = i;
+				break;
+			}
+		}
+	}
+	gen_rand_str(RAND_SOCKET_NAME, sizeof(SOCKET_NAME));
+	memcpy(buf + SOCKET_OFF, RAND_SOCKET_NAME, sizeof(SOCKET_NAME));
+	munmap(buf, size);
+}
+
 static void magisk_init_daemon() {
 	setsid();
 
@@ -381,6 +400,7 @@ static void magisk_init_daemon() {
 	dup3(null, STDIN_FILENO, O_CLOEXEC);
 	dup3(null, STDOUT_FILENO, O_CLOEXEC);
 	dup3(null, STDERR_FILENO, O_CLOEXEC);
+	if (null > STDERR_FILENO)
 		close(null);
 
 	// Transit our context to su (mimic setcon)
@@ -398,6 +418,7 @@ static void magisk_init_daemon() {
 	while (1) {
 		struct sockaddr_un sun;
 		fd = setup_socket(&sun);
+		memcpy(sun.sun_path + 1, RAND_SOCKET_NAME, sizeof(SOCKET_NAME));
 		while (connect(fd, (struct sockaddr*) &sun, sizeof(sun)))
 			usleep(10000); /* Wait 10 ms after each try */
 
@@ -446,6 +467,7 @@ int main(int argc, char *argv[]) {
 	dump_magisk("/overlay/sbin/magisk", 0755);
 	mkdir("/overlay/root", 0755);
 	link("/init", "/overlay/root/magiskinit");
+	patch_socket_name("/overlay/sbin/magisk");
 
 	struct cmdline cmd;
 	parse_cmdline(&cmd);
@@ -535,6 +557,9 @@ int main(int argc, char *argv[]) {
 		}
 
 		close(overlay);
+		close(STDIN_FILENO);
+		close(STDOUT_FILENO);
+		close(STDERR_FILENO);
 
 		if (fork_dont_care() == 0) {
 			strcpy(argv[0], "magiskinit");

native/jni/core/socket.c

@@ -13,7 +13,8 @@ int setup_socket(struct sockaddr_un *sun) {
 	int fd = xsocket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
 	memset(sun, 0, sizeof(*sun));
 	sun->sun_family = AF_LOCAL;
-    memcpy(sun->sun_path, REQUESTOR_DAEMON_PATH, sizeof(REQUESTOR_DAEMON_PATH) - 1);
+	sun->sun_path[0] = '\0';
+	memcpy(sun->sun_path + 1, SOCKET_NAME, sizeof(SOCKET_NAME));
 	return fd;
 }
 

native/jni/include/magisk.h

@@ -7,7 +7,7 @@
 #include "logging.h"
 
 #define MAGISK_VER_STR  xstr(MAGISK_VERSION) ":MAGISK"
-#define REQUESTOR_DAEMON_PATH     "\0MAGISK"
+#define SOCKET_NAME     "d30138f2310a9fb9c54a3e0c21f58591"
 
 #ifndef ARG_MAX
 #define ARG_MAX 4096

native/jni/include/utils.h

@@ -90,6 +90,7 @@ void get_client_cred(int fd, struct ucred *cred);
 int switch_mnt_ns(int pid);
 int fork_dont_care();
 void wait_till_exists(const char *target);
+void gen_rand_str(char *buf, int len);
 
 // file.c
 

native/jni/utils/misc.c

@@ -17,6 +17,7 @@
 #include <sys/wait.h>
 #include <sys/stat.h>
 #include <sys/inotify.h>
+#include <sys/sysmacros.h>
 
 #include "logging.h"
 #include "utils.h"
@@ -341,3 +342,21 @@ void wait_till_exists(const char *target) {
 	}
 	close(fd);
 }
+
+void gen_rand_str(char *buf, int len) {
+	const char base[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.";
+	int urandom;
+	if (access("/dev/urandom", R_OK) == 0) {
+		urandom = xopen("/dev/urandom", O_RDONLY | O_CLOEXEC);
+	} else {
+		mknod("/urandom", S_IFCHR | 0666, makedev(1, 9));
+		urandom = xopen("/urandom", O_RDONLY | O_CLOEXEC);
+		unlink("/urandom");
+	}
+	xxread(urandom, buf, len - 1);
+	close(urandom);
+	for (int i = 0; i < len - 1; ++i) {
+		buf[i] = base[buf[i] % (sizeof(base) - 1)];
+	}
+	buf[len - 1] = '\0';
+}