Allow to de-activate log watchlog (#20)

Requested by #14, a switch is added to the release version.
Patch of msvamp rejected in original repository
mywalk added ui interface

Co-authored-by: mywalk <66966897+mywalkb@users.noreply.github.com>

app/src/main/java/org/lsposed/manager/ConfigManager.java

@@ -178,6 +178,25 @@ public class ConfigManager {
         }
     }
 
+    public static boolean isLogWatchdogEnabled() {
+        try {
+            return LSPManagerServiceHolder.getService().isLogWatchdogEnabled();
+        } catch (RemoteException e) {
+            Log.e(App.TAG, Log.getStackTraceString(e));
+            return false;
+        }
+    }
+
+    public static boolean setLogWatchdog(boolean enabled) {
+        try {
+            LSPManagerServiceHolder.getService().setLogWatchdog(enabled);
+            return true;
+        } catch (RemoteException e) {
+            Log.e(App.TAG, Log.getStackTraceString(e));
+            return false;
+        }
+    }
+
     public static ParcelFileDescriptor getLog(boolean verbose) {
         try {
             return verbose ? LSPManagerServiceHolder.getService().getVerboseLog() : LSPManagerServiceHolder.getService().getModulesLog();

app/src/main/java/org/lsposed/manager/ui/fragment/SettingsFragment.java

@@ -160,6 +160,13 @@ public class SettingsFragment extends BaseFragment {
                 prefVerboseLogs.setOnPreferenceChangeListener((preference, newValue) -> ConfigManager.setVerboseLogEnabled(!(boolean) newValue));
             }
 
+            MaterialSwitchPreference prefEnableLog = findPreference("enable_log_watchdog");
+            if (prefEnableLog != null) {
+                prefEnableLog.setEnabled(!BuildConfig.DEBUG && installed);
+                prefEnableLog.setChecked(!installed || ConfigManager.isLogWatchdogEnabled());
+                prefEnableLog.setOnPreferenceChangeListener((preference, newValue) -> ConfigManager.setLogWatchdog((boolean) newValue));
+            }
+
             MaterialSwitchPreference prefDexObfuscate = findPreference("enable_dex_obfuscate");
             if (prefDexObfuscate != null) {
                 prefDexObfuscate.setEnabled(installed);

app/src/main/res/values/strings.xml

@@ -175,6 +175,8 @@
     <string name="settings_group_framework">Framework</string>
     <string name="settings_disable_verbose_log">Disable verbose logs</string>
     <string name="settings_disable_verbose_log_summary">Report issues request to include verbose logs</string>
+    <string name="settings_enable_log_watchdog">Enable log watchdog</string>
+    <string name="settings_enable_log_watchdog_summary">Log watchdog of LSPosed modifies system properties, which could be exploited to detect LSPosed</string>
     <string name="pure_black_dark_theme">Black dark theme</string>
     <string name="pure_black_dark_theme_summary">Use the pure black theme if dark theme is enabled</string>
     <string name="settings_group_theme">Theme</string>

app/src/main/res/xml/prefs.xml

@@ -91,6 +91,14 @@
             android:summary="@string/settings_disable_verbose_log_summary"
             android:title="@string/settings_disable_verbose_log" />
 
+        <rikka.material.preference.MaterialSwitchPreference
+            android:defaultValue="true"
+            android:icon="@drawable/ic_outline_assignment_24"
+            android:key="enable_log_watchdog"
+            android:persistent="false"
+            android:summary="@string/settings_enable_log_watchdog_summary"
+            android:title="@string/settings_enable_log_watchdog" />
+
         <rikka.material.preference.MaterialSwitchPreference
             android:defaultValue="true"
             android:icon="@drawable/ic_outline_shield_24"

daemon/src/main/java/org/lsposed/lspd/service/ConfigManager.java

@@ -99,6 +99,7 @@ public class ConfigManager {
     private final SQLiteDatabase db = openDb();
 
     private boolean verboseLog = true;
+    private boolean logWatchdog = true;
     private boolean dexObfuscate = true;
     private boolean enableStatusNotification = true;
     private Path miscPath = null;
@@ -270,6 +271,9 @@ public class ConfigManager {
         Object bool = config.get("enable_verbose_log");
         verboseLog = bool == null || (boolean) bool;
 
+        bool = config.get("enable_log_watchdog");
+        logWatchdog = bool == null || (boolean) bool;
+
         bool = config.get("enable_dex_obfuscate");
         dexObfuscate = bool == null || (boolean) bool;
 
@@ -1048,6 +1052,21 @@ public class ConfigManager {
         return BuildConfig.DEBUG || verboseLog;
     }
 
+    public void setLogWatchdog(boolean on) {
+        var logcatService = ServiceManager.getLogcatService();
+        if (on) {
+            logcatService.enableWatchdog();
+        } else {
+            logcatService.disableWatchdog();
+        }
+        updateModulePrefs("lspd", 0, "config", "enable_log_watchdog", on);
+        logWatchdog = on;
+    }
+
+    public boolean isLogWatchdogEnabled() {
+        return logWatchdog;
+    }
+
     public void setDexObfuscate(boolean on) {
         updateModulePrefs("lspd", 0, "config", "enable_dex_obfuscate", on);
     }

daemon/src/main/java/org/lsposed/lspd/service/LSPManagerService.java

@@ -546,4 +546,14 @@ public class LSPManagerService extends ILSPManagerService.Stub {
             return 0;
         }
     }
+
+    @Override
+    public void setLogWatchdog(boolean enabled) {
+        ConfigManager.getInstance().setLogWatchdog(enabled);
+    }
+
+    @Override
+    public boolean isLogWatchdogEnabled() {
+        return ConfigManager.getInstance().isLogWatchdogEnabled();
+    }
 }

daemon/src/main/java/org/lsposed/lspd/service/LogcatService.java

@@ -182,6 +182,14 @@ public class LogcatService implements Runnable {
         Log.i(TAG, "!!stop_verbose!!");
     }
 
+    public void enableWatchdog() {
+        Log.i(TAG, "!!start_watchdog!!");
+    }
+
+    public void disableWatchdog() {
+        Log.i(TAG, "!!stop_watchdog!!");
+    }
+
     public void refresh(boolean isVerboseLog) {
         if (isVerboseLog) {
             Log.i(TAG, "!!refresh_verbose!!");

daemon/src/main/java/org/lsposed/lspd/service/ServiceManager.java

@@ -115,6 +115,15 @@ public class ServiceManager {
         logcatService = new LogcatService();
         logcatService.start();
 
+        // get config before package service is started
+        // otherwise getInstance will trigger module/scope cache
+        var configManager = ConfigManager.getInstance();
+        // --- DO NOT call ConfigManager.getInstance later!!! ---
+
+        // Unblock log watchdog before starting anything else
+        if (configManager.isLogWatchdogEnabled())
+            logcatService.enableWatchdog();
+
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R)
             permissionManagerWorkaround();
 
@@ -133,11 +142,6 @@ public class ServiceManager {
 
         systemServerService.putBinderForSystemServer();
 
-        // get config before package service is started
-        // otherwise getInstance will trigger module/scope cache
-        var configManager = ConfigManager.getInstance();
-        // --- DO NOT call ConfigManager.getInstance later!!! ---
-
         ActivityThread.systemMain();
 
         DdmHandleAppName.setAppName("org.lsposed.daemon", 0);

daemon/src/main/jni/logcat.cpp

@@ -5,6 +5,7 @@
 #include <string>
 #include <android/log.h>
 #include <array>
+#include <atomic>
 #include <cinttypes>
 #include <chrono>
 #include <thread>
@@ -129,6 +130,7 @@ private:
     pid_t my_pid_ = getpid();
 
     bool verbose_ = true;
+    std::atomic<bool> enable_watchdog = std::atomic<bool>(false);
 };
 
 size_t Logcat::PrintLogLine(const AndroidLogEntry &entry, FILE *out) {
@@ -241,6 +243,12 @@ void Logcat::ProcessBuffer(struct log_msg *buf) {
             RefreshFd(false);
         } else if (msg == "!!refresh_verbose!!"sv) {
             RefreshFd(true);
+        } else if (msg == "!!start_watchdog!!"sv) {
+            enable_watchdog = true;
+            enable_watchdog.notify_one();
+        } else if (msg == "!!stop_watchdog!!"sv) {
+            enable_watchdog = false;
+            enable_watchdog.notify_one();
         }
     }
 }
@@ -253,6 +261,7 @@ void Logcat::EnsureLogWatchDog() {
     constexpr static size_t kErr = -1;
     std::thread watch_dog([this] {
         while (true) {
+            enable_watchdog.wait(false);
             auto logd_size = GetByteProp(kLogdSizeProp);
             auto logd_tag = GetStrProp(kLogdTagProp);
             auto logd_main_size = GetByteProp(kLogdMainSizeProp);
@@ -277,8 +286,9 @@ void Logcat::EnsureLogWatchDog() {
                 }, &serial);
             }
             if (!__system_property_wait(pi, serial, &serial, nullptr)) break;
-            if (pi != nullptr) Log("\nResetting log settings\n");
+            if (pi != nullptr) {
-            else std::this_thread::sleep_for(1s);
+                if (enable_watchdog) Log("\nResetting log settings\n");
+            } else std::this_thread::sleep_for(1s);
             // log tag prop was not found; to avoid frequently trigger wait, sleep for a while
         }
     });

services/manager-service/src/main/aidl/org/lsposed/lspd/ILSPManagerService.aidl

@@ -87,4 +87,8 @@ interface ILSPManagerService {
     boolean enableStatusNotification() = 47;
 
     void setEnableStatusNotification(boolean enable) = 48;
+
+    void setLogWatchdog(boolean enable) = 49;
+
+    boolean isLogWatchdogEnabled() = 50;
 }