Use component name as targets

Services can name their process name arbitrarily, for instance the service in
com.google.android.gms that is responsible for SafetyNet is named
com.google.android.gms.unstable. There are many apps out in the wild use
dedicated services with special names to detect root, and previously the user
is expected to add all of them to the hide list.

In this commit, we change from targeting process names to component names.
On Android, component names are composed of <pkg>/<cls>. When targeting
component names, we can always know what application spawned the new process.
This means that if the user adds a package name to the hidelist, MagiskHide can
now target ALL possible processes of that specific application.

To abide with this change, the default SafetyNet target is now changed from
com.google.android.gms.unstable (process name) to
com.google.android.gms/.droidguard.DroidGuardService (component name)

native/jni/magiskhide/hide_utils.cpp

@@ -268,7 +268,8 @@ int launch_magiskhide(int client) {
 		goto error;
 
 	// Add SafetyNet by default
-	add_list("com.google.android.gms.unstable");
+	rm_list("com.google.android.gms.unstable");
+	add_list("com.google.android.gms/.droidguard.DroidGuardService");
 
 	// Get thread reference
 	proc_monitor_thread = pthread_self();

native/jni/magiskhide/magiskhide.cpp

@@ -17,14 +17,18 @@ bool hide_enabled = false;
 [[noreturn]] static void usage(char *arg0) {
 	fprintf(stderr,
 		"MagiskHide v" xstr(MAGISK_VERSION) "(" xstr(MAGISK_VER_CODE) ") (by topjohnwu)\n\n"
-		"Usage: %s [--options [arguments...] ]\n\n"
+		"Usage: %s [--option [arguments...] ]\n\n"
 		"Options:\n"
   		"  --status          Return the status of MagiskHide\n"
 		"  --enable          Start magiskhide\n"
 		"  --disable         Stop magiskhide\n"
-		"  --add PROCESS     Add PROCESS to the hide list\n"
-		"  --rm PROCESS      Remove PROCESS from the hide list\n"
+		"  --add TARGET      Add TARGET to the hide list\n"
+		"  --rm TARGET       Remove TARGET from the hide list\n"
 		"  --ls              Print out the current hide list\n"
+		"\n"
+		"TARGET can be either a package name or a specific component name\n"
+		"If TARGET is a package name, all components of the app will be targeted\n"
+		"A component name is composed of <pkg>/<cls>\n"
 		, arg0);
 	exit(1);
 }
@@ -115,10 +119,10 @@ int magiskhide_main(int argc, char *argv[]) {
 		fprintf(stderr, "MagiskHide is enabled\n");
 		break;
 	case HIDE_ITEM_EXIST:
-		fprintf(stderr, "Process [%s] already exists in hide list\n", argv[2]);
+		fprintf(stderr, "[%s] already exists in hide list\n", argv[2]);
 		break;
 	case HIDE_ITEM_NOT_EXIST:
-		fprintf(stderr, "Process [%s] does not exist in hide list\n", argv[2]);
+		fprintf(stderr, "[%s] does not exist in hide list\n", argv[2]);
 		break;
 
 	/* Errors */

native/jni/magiskhide/proc_monitor.cpp

@@ -20,7 +20,6 @@
 #include "daemon.h"
 #include "utils.h"
 #include "magiskhide.h"
-#include "flags.h"
 
 static int sockfd = -1;
 extern char *system_block, *vendor_block, *magiskloop;
@@ -61,7 +60,7 @@ static int parse_ppid(int pid) {
 }
 
 static void hide_daemon(int pid) {
-	LOGD("hide_daemon: start unmount for pid=[%d]\n", pid);
+	LOGD("hide_daemon: handling pid=[%d]\n", pid);
 
 	char buffer[4096];
 	Vector<CharArray> mounts;
@@ -130,32 +129,32 @@ void proc_monitor() {
 	FILE *log_in = fdopen(sockfd, "r");
 	char buf[4096];
 	while (fgets(buf, sizeof(buf), log_in)) {
-		char *ss = strchr(buf, '[') + 1;
-		int pid, ppid, num = 0;
-		char *pos = ss, proc[256];
+		char *log;
+		int pid, ppid;
 		struct stat ns, pns;
 
-		while((pos = strchr(pos, ','))) {
-			*pos = ' ';
-			++num;
-		}
+		if ((log = strchr(buf, '[')) == nullptr)
+			continue;
 
-		if(sscanf(ss, num == 6 ? "%*d %d %*d %*d %256s" : "%*d %d %*d %256s", &pid, proc) != 2)
+		// Extract pid
+		if (sscanf(log, "[%*d,%d", &pid) != 1)
+			continue;
+
+		// Extract last token (component name)
+		const char *tok, *cpnt = "";
+		while ((tok = strtok_r(nullptr, ",[]\n", &log)))
+			cpnt = tok;
+		if (cpnt[0] == '\0')
 			continue;
 
 		// Make sure our target is alive
 		if ((ppid = parse_ppid(pid)) < 0 || read_ns(ppid, &pns))
 			continue;
 
-		// Allow hiding sub-services of applications
-		char *colon = strchr(proc, ':');
-		if (colon)
-			*colon = '\0';
-
 		bool hide = false;
 		pthread_mutex_lock(&list_lock);
 		for (auto &s : hide_list) {
-			if (s == proc) {
+			if (strncmp(cpnt, s, s.size() - 1) == 0) {
 				hide = true;
 				break;
 			}
@@ -172,20 +171,11 @@ void proc_monitor() {
 		if (kill(pid, SIGSTOP) == -1)
 			continue;
 
-		// Restore the colon so we can log the actual process name
-		if (colon)
-			*colon = ':';
-#ifdef MAGISK_DEBUG
-		LOGI("proc_monitor: %s (PID=[%d] ns=%llu)(PPID=[%d] ns=%llu)\n",
-			 proc, pid, ns.st_ino, ppid, pns.st_ino);
-#else
-		LOGI("proc_monitor: %s\n", proc);
-#endif
-
 		/*
 		 * The setns system call do not support multithread processes
 		 * We have to fork a new process, setns, then do the unmounts
 		 */
+		LOGI("proc_monitor: %s PID=[%d] ns=[%llu]\n", cpnt, pid, ns.st_ino);
 		if (fork_dont_care() == 0)
 			hide_daemon(pid);
 	}

native/jni/utils/misc.cpp

@@ -256,9 +256,9 @@ int exec_command(int err, int *fd, void (*cb)(void), const char *argv0, ...) {
 }
 
 char *strdup2(const char *s, size_t *size) {
-	size_t l = strlen(s) + 1;
-	char *buf = new char[l];
-	memcpy(buf, s, l);
-	if (size) *size = l;
+	size_t len = strlen(s) + 1;
+	char *buf = new char[len];
+	memcpy(buf, s, len);
+	if (size) *size = len;
 	return buf;
 }