| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.server; |
| |
| import android.content.ContentResolver; |
| import android.content.Context; |
| import android.content.pm.UserInfo; |
| import android.os.Build; |
| import android.os.FileUtils; |
| import android.os.RecoverySystem; |
| import android.os.SystemClock; |
| import android.os.SystemProperties; |
| import android.os.UserHandle; |
| import android.os.UserManager; |
| import android.provider.Settings; |
| import android.text.format.DateUtils; |
| import android.util.ExceptionUtils; |
| import android.util.MathUtils; |
| import android.util.Slog; |
| import android.util.SparseArray; |
| |
| import com.android.internal.util.ArrayUtils; |
| |
| import java.io.File; |
| |
| /** |
| * Utilities to help rescue the system from crash loops. Callers are expected to |
| * report boot events and persistent app crashes, and if they happen frequently |
| * enough this class will slowly escalate through several rescue operations |
| * before finally rebooting and prompting the user if they want to wipe data as |
| * a last resort. |
| * |
| * @hide |
| */ |
| public class RescueParty { |
| private static final String TAG = "RescueParty"; |
| |
| private static final String PROP_DISABLE_RESCUE = "persist.sys.disable_rescue"; |
| private static final String PROP_RESCUE_LEVEL = "sys.rescue_level"; |
| private static final String PROP_RESCUE_BOOT_COUNT = "sys.rescue_boot_count"; |
| private static final String PROP_RESCUE_BOOT_START = "sys.rescue_boot_start"; |
| |
| private static final int LEVEL_NONE = 0; |
| private static final int LEVEL_RESET_SETTINGS_UNTRUSTED_DEFAULTS = 1; |
| private static final int LEVEL_RESET_SETTINGS_UNTRUSTED_CHANGES = 2; |
| private static final int LEVEL_RESET_SETTINGS_TRUSTED_DEFAULTS = 3; |
| private static final int LEVEL_FACTORY_RESET = 4; |
| |
| /** Threshold for boot loops */ |
| private static final Threshold sBoot = new BootThreshold(); |
| /** Threshold for app crash loops */ |
| private static SparseArray<Threshold> sApps = new SparseArray<>(); |
| |
| private static boolean isDisabled() { |
| // We're disabled on all engineering devices |
| if (Build.IS_ENG) { |
| Slog.v(TAG, "Disabled because of eng build"); |
| return true; |
| } |
| |
| // We're disabled on userdebug devices connected over USB, since that's |
| // a decent signal that someone is actively trying to debug the device, |
| // or that it's in a lab environment. |
| if (Build.IS_USERDEBUG && isUsbActive()) { |
| Slog.v(TAG, "Disabled because of active USB connection"); |
| return true; |
| } |
| |
| // One last-ditch check |
| if (SystemProperties.getBoolean(PROP_DISABLE_RESCUE, false)) { |
| Slog.v(TAG, "Disabled because of manual property"); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| /** |
| * Take note of a boot event. If we notice too many of these events |
| * happening in rapid succession, we'll send out a rescue party. |
| */ |
| public static void noteBoot(Context context) { |
| if (isDisabled()) return; |
| if (sBoot.incrementAndTest()) { |
| sBoot.reset(); |
| incrementRescueLevel(sBoot.uid); |
| executeRescueLevel(context); |
| } |
| } |
| |
| /** |
| * Take note of a persistent app crash. If we notice too many of these |
| * events happening in rapid succession, we'll send out a rescue party. |
| */ |
| public static void notePersistentAppCrash(Context context, int uid) { |
| if (isDisabled()) return; |
| Threshold t = sApps.get(uid); |
| if (t == null) { |
| t = new AppThreshold(uid); |
| sApps.put(uid, t); |
| } |
| if (t.incrementAndTest()) { |
| t.reset(); |
| incrementRescueLevel(t.uid); |
| executeRescueLevel(context); |
| } |
| } |
| |
| /** |
| * Check if we're currently attempting to reboot for a factory reset. |
| */ |
| public static boolean isAttemptingFactoryReset() { |
| return SystemProperties.getInt(PROP_RESCUE_LEVEL, LEVEL_NONE) == LEVEL_FACTORY_RESET; |
| } |
| |
| /** |
| * Escalate to the next rescue level. After incrementing the level you'll |
| * probably want to call {@link #executeRescueLevel(Context)}. |
| */ |
| private static void incrementRescueLevel(int triggerUid) { |
| final int level = MathUtils.constrain( |
| SystemProperties.getInt(PROP_RESCUE_LEVEL, LEVEL_NONE) + 1, |
| LEVEL_NONE, LEVEL_FACTORY_RESET); |
| SystemProperties.set(PROP_RESCUE_LEVEL, Integer.toString(level)); |
| |
| EventLogTags.writeRescueLevel(level, triggerUid); |
| Slog.w(TAG, "Incremented rescue level to " + levelToString(level)); |
| } |
| |
| /** |
| * Called when {@code SettingsProvider} has been published, which is a good |
| * opportunity to reset any settings depending on our rescue level. |
| */ |
| public static void onSettingsProviderPublished(Context context) { |
| executeRescueLevel(context); |
| } |
| |
| private static void executeRescueLevel(Context context) { |
| final int level = SystemProperties.getInt(PROP_RESCUE_LEVEL, LEVEL_NONE); |
| if (level == LEVEL_NONE) return; |
| |
| Slog.w(TAG, "Attempting rescue level " + levelToString(level)); |
| try { |
| executeRescueLevelInternal(context, level); |
| EventLogTags.writeRescueSuccess(level); |
| Slog.d(TAG, "Finished rescue level " + levelToString(level)); |
| } catch (Throwable t) { |
| EventLogTags.writeRescueFailure(level, ExceptionUtils.getCompleteMessage(t)); |
| Slog.e(TAG, "Failed rescue level " + levelToString(level), t); |
| } |
| } |
| |
| private static void executeRescueLevelInternal(Context context, int level) throws Exception { |
| switch (level) { |
| case LEVEL_RESET_SETTINGS_UNTRUSTED_DEFAULTS: |
| resetAllSettings(context, Settings.RESET_MODE_UNTRUSTED_DEFAULTS); |
| break; |
| case LEVEL_RESET_SETTINGS_UNTRUSTED_CHANGES: |
| resetAllSettings(context, Settings.RESET_MODE_UNTRUSTED_CHANGES); |
| break; |
| case LEVEL_RESET_SETTINGS_TRUSTED_DEFAULTS: |
| resetAllSettings(context, Settings.RESET_MODE_TRUSTED_DEFAULTS); |
| break; |
| case LEVEL_FACTORY_RESET: |
| RecoverySystem.rebootPromptAndWipeUserData(context, TAG); |
| break; |
| } |
| } |
| |
| private static void resetAllSettings(Context context, int mode) throws Exception { |
| // Try our best to reset all settings possible, and once finished |
| // rethrow any exception that we encountered |
| Exception res = null; |
| final ContentResolver resolver = context.getContentResolver(); |
| try { |
| Settings.Global.resetToDefaultsAsUser(resolver, null, mode, UserHandle.USER_SYSTEM); |
| } catch (Throwable t) { |
| res = new RuntimeException("Failed to reset global settings", t); |
| } |
| for (int userId : getAllUserIds(context)) { |
| try { |
| Settings.Secure.resetToDefaultsAsUser(resolver, null, mode, userId); |
| } catch (Throwable t) { |
| res = new RuntimeException("Failed to reset secure settings for " + userId, t); |
| } |
| } |
| if (res != null) { |
| throw res; |
| } |
| } |
| |
| /** |
| * Threshold that can be triggered if a number of events occur within a |
| * window of time. |
| */ |
| private abstract static class Threshold { |
| public abstract int getCount(); |
| public abstract void setCount(int count); |
| public abstract long getStart(); |
| public abstract void setStart(long start); |
| |
| private final int uid; |
| private final int triggerCount; |
| private final long triggerWindow; |
| |
| public Threshold(int uid, int triggerCount, long triggerWindow) { |
| this.uid = uid; |
| this.triggerCount = triggerCount; |
| this.triggerWindow = triggerWindow; |
| } |
| |
| public void reset() { |
| setCount(0); |
| setStart(0); |
| } |
| |
| /** |
| * @return if this threshold has been triggered |
| */ |
| public boolean incrementAndTest() { |
| final long now = SystemClock.elapsedRealtime(); |
| final long window = now - getStart(); |
| if (window > triggerWindow) { |
| setCount(1); |
| setStart(now); |
| return false; |
| } else { |
| int count = getCount() + 1; |
| setCount(count); |
| EventLogTags.writeRescueNote(uid, count, window); |
| Slog.w(TAG, "Noticed " + count + " events for UID " + uid + " in last " |
| + (window / 1000) + " sec"); |
| return (count >= triggerCount); |
| } |
| } |
| } |
| |
| /** |
| * Specialization of {@link Threshold} for monitoring boot events. It stores |
| * counters in system properties for robustness. |
| */ |
| private static class BootThreshold extends Threshold { |
| public BootThreshold() { |
| // We're interested in 5 events in any 300 second period; this |
| // window is super relaxed because booting can take a long time if |
| // forced to dexopt things. |
| super(android.os.Process.ROOT_UID, 5, 300 * DateUtils.SECOND_IN_MILLIS); |
| } |
| |
| @Override |
| public int getCount() { |
| return SystemProperties.getInt(PROP_RESCUE_BOOT_COUNT, 0); |
| } |
| |
| @Override |
| public void setCount(int count) { |
| SystemProperties.set(PROP_RESCUE_BOOT_COUNT, Integer.toString(count)); |
| } |
| |
| @Override |
| public long getStart() { |
| return SystemProperties.getLong(PROP_RESCUE_BOOT_START, 0); |
| } |
| |
| @Override |
| public void setStart(long start) { |
| SystemProperties.set(PROP_RESCUE_BOOT_START, Long.toString(start)); |
| } |
| } |
| |
| /** |
| * Specialization of {@link Threshold} for monitoring app crashes. It stores |
| * counters in memory. |
| */ |
| private static class AppThreshold extends Threshold { |
| private int count; |
| private long start; |
| |
| public AppThreshold(int uid) { |
| // We're interested in 5 events in any 30 second period; apps crash |
| // pretty quickly so we can keep a tight leash on them. |
| super(uid, 5, 30 * DateUtils.SECOND_IN_MILLIS); |
| } |
| |
| @Override public int getCount() { return count; } |
| @Override public void setCount(int count) { this.count = count; } |
| @Override public long getStart() { return start; } |
| @Override public void setStart(long start) { this.start = start; } |
| } |
| |
| private static int[] getAllUserIds(Context context) { |
| int[] userIds = { UserHandle.USER_SYSTEM }; |
| try { |
| final UserManager um = context.getSystemService(UserManager.class); |
| for (UserInfo user : um.getUsers()) { |
| if (user.id != UserHandle.USER_SYSTEM) { |
| userIds = ArrayUtils.appendInt(userIds, user.id); |
| } |
| } |
| } catch (Throwable t) { |
| Slog.w(TAG, "Trouble discovering users", t); |
| } |
| return userIds; |
| } |
| |
| /** |
| * Hacky test to check if the device has an active USB connection, which is |
| * a good proxy for someone doing local development work. |
| */ |
| private static boolean isUsbActive() { |
| try { |
| final String state = FileUtils |
| .readTextFile(new File("/sys/class/android_usb/android0/state"), 128, ""); |
| return "CONFIGURED".equals(state.trim()); |
| } catch (Throwable t) { |
| Slog.w(TAG, "Failed to determine if device was on USB", t); |
| return false; |
| } |
| } |
| |
| private static String levelToString(int level) { |
| switch (level) { |
| case LEVEL_NONE: return "NONE"; |
| case LEVEL_RESET_SETTINGS_UNTRUSTED_DEFAULTS: return "RESET_SETTINGS_UNTRUSTED_DEFAULTS"; |
| case LEVEL_RESET_SETTINGS_UNTRUSTED_CHANGES: return "RESET_SETTINGS_UNTRUSTED_CHANGES"; |
| case LEVEL_RESET_SETTINGS_TRUSTED_DEFAULTS: return "RESET_SETTINGS_TRUSTED_DEFAULTS"; |
| case LEVEL_FACTORY_RESET: return "FACTORY_RESET"; |
| default: return Integer.toString(level); |
| } |
| } |
| } |