From 081074ad9d5c02e589f265373c0dfa867c9eeaff Mon Sep 17 00:00:00 2001
From: topjohnwu <topjohnwu@gmail.com>
Date: Fri, 8 Mar 2019 23:53:53 -0500
Subject: [PATCH] Better zygote process detection

---
 native/jni/include/daemon.h            |  1 -
 native/jni/magiskhide/hide_utils.cpp   |  3 +-
 native/jni/magiskhide/magiskhide.h     |  1 -
 native/jni/magiskhide/proc_monitor.cpp | 52 ++++++++++++++++++--------
 4 files changed, 38 insertions(+), 19 deletions(-)

diff --git a/native/jni/include/daemon.h b/native/jni/include/daemon.h
index 77b1a7166..f8edcd5b0 100644
--- a/native/jni/include/daemon.h
+++ b/native/jni/include/daemon.h
@@ -79,7 +79,6 @@ void install_apk(const char *apk);
  **************/
 
 void magiskhide_handler(int client);
-void zygote_notify(int client, struct ucred *cred);
 
 /*************
  * Superuser *
diff --git a/native/jni/magiskhide/hide_utils.cpp b/native/jni/magiskhide/hide_utils.cpp
index 1bab2a6e5..4e9d89e9c 100644
--- a/native/jni/magiskhide/hide_utils.cpp
+++ b/native/jni/magiskhide/hide_utils.cpp
@@ -18,7 +18,7 @@
 
 using namespace std;
 
-pthread_t proc_monitor_thread;
+static pthread_t proc_monitor_thread;
 
 static const char *prop_key[] =
 	{ "ro.boot.vbmeta.device_state", "ro.boot.verifiedbootstate", "ro.boot.flash.locked",
@@ -327,4 +327,3 @@ void auto_start_magiskhide() {
 		});
 	}
 }
-
diff --git a/native/jni/magiskhide/magiskhide.h b/native/jni/magiskhide/magiskhide.h
index eaaa082f0..4cb69ed1e 100644
--- a/native/jni/magiskhide/magiskhide.h
+++ b/native/jni/magiskhide/magiskhide.h
@@ -37,7 +37,6 @@ void clean_magisk_props();
 void crawl_procfs(const std::function<bool (int)> &fn);
 bool proc_name_match(int pid, const char *name);
 
-extern pthread_t proc_monitor_thread;
 extern bool hide_enabled;
 extern pthread_mutex_t monitor_lock;
 extern std::set<std::pair<std::string, std::string>> hide_set;
diff --git a/native/jni/magiskhide/proc_monitor.cpp b/native/jni/magiskhide/proc_monitor.cpp
index f3c9842c6..6b6a55322 100644
--- a/native/jni/magiskhide/proc_monitor.cpp
+++ b/native/jni/magiskhide/proc_monitor.cpp
@@ -63,6 +63,22 @@ static inline void lazy_unmount(const char* mountpoint) {
 		LOGD("hide_daemon: Unmounted (%s)\n", mountpoint);
 }
 
+static int parse_ppid(int pid) {
+	char path[32];
+	int ppid;
+
+	sprintf(path, "/proc/%d/stat", pid);
+	FILE *stat = fopen(path, "re");
+	if (stat == nullptr)
+		return -1;
+
+	/* PID COMM STATE PPID ..... */
+	fscanf(stat, "%*d %*s %*c %d", &ppid);
+	fclose(stat);
+
+	return ppid;
+}
+
 static long xptrace(bool log, int request, pid_t pid, void *addr, void *data) {
 	long ret = ptrace(request, pid, addr, data);
 	if (log && ret == -1)
@@ -115,18 +131,25 @@ static bool parse_packages_xml(string_view s) {
 }
 
 static void check_zygote() {
-	crawl_procfs([](int pid) -> bool {
-		char buf[512];
-		snprintf(buf, sizeof(buf), "/proc/%d/cmdline", pid);
-		FILE *f = fopen(buf, "re");
-		if (f) {
-			fgets(buf, sizeof(buf), f);
-			if (strncmp(buf, "zygote", 6) == 0)
-				new_zygote(pid);
-			fclose(f);
-		}
-		return true;
-	});
+	int min_zyg = 1;
+	if (access("/system/bin/app_process64", R_OK) == 0)
+		min_zyg = 2;
+	for (bool first = true; zygote_map.size() < min_zyg; first = false) {
+		if (!first)
+			usleep(10000);
+		crawl_procfs([](int pid) -> bool {
+			char buf[512];
+			snprintf(buf, sizeof(buf), "/proc/%d/cmdline", pid);
+			FILE *f = fopen(buf, "re");
+			if (f) {
+				fgets(buf, sizeof(buf), f);
+				if (strncmp(buf, "zygote", 6) == 0 && parse_ppid(pid) == 1)
+					new_zygote(pid);
+				fclose(f);
+			}
+			return true;
+		});
+	}
 }
 
 void *update_uid_map(void*) {
@@ -138,7 +161,7 @@ void *update_uid_map(void*) {
 
 /*************************
  * The actual hide daemon
- **************************/
+ *************************/
 
 static void hide_daemon(int pid) {
 	RunFinally fin([=]() -> void {
@@ -208,8 +231,7 @@ static void inotify_event(int) {
 	read(inotify_fd, buf, sizeof(buf));
 	if ((event->mask & IN_CLOSE_WRITE) && strcmp(event->name, "packages.xml") == 0) {
 		LOGD("proc_monitor: /data/system/packages.xml updated\n");
-		check_zygote();
-		update_uid_map();
+		new_daemon_thread(update_uid_map);
 	}
 }