| /* |
| * 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.net.watchlist; |
| |
| import android.annotation.Nullable; |
| import android.content.ContentResolver; |
| import android.content.Context; |
| import android.content.pm.ApplicationInfo; |
| import android.content.pm.PackageManager; |
| import android.content.pm.PackageManager.NameNotFoundException; |
| import android.os.Bundle; |
| import android.os.DropBoxManager; |
| import android.os.Handler; |
| import android.os.Looper; |
| import android.os.Message; |
| import android.os.UserHandle; |
| import android.provider.Settings; |
| import android.text.TextUtils; |
| import android.util.Slog; |
| |
| import com.android.internal.annotations.GuardedBy; |
| import com.android.internal.annotations.VisibleForTesting; |
| import com.android.internal.util.ArrayUtils; |
| import com.android.internal.util.HexDump; |
| |
| import java.io.File; |
| import java.io.IOException; |
| import java.security.NoSuchAlgorithmException; |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.TimeUnit; |
| |
| /** |
| * A Handler class for network watchlist logging on a background thread. |
| */ |
| class WatchlistLoggingHandler extends Handler { |
| |
| private static final String TAG = WatchlistLoggingHandler.class.getSimpleName(); |
| private static final boolean DEBUG = NetworkWatchlistService.DEBUG; |
| |
| @VisibleForTesting |
| static final int LOG_WATCHLIST_EVENT_MSG = 1; |
| @VisibleForTesting |
| static final int REPORT_RECORDS_IF_NECESSARY_MSG = 2; |
| |
| private static final long ONE_DAY_MS = TimeUnit.DAYS.toMillis(1); |
| private static final String DROPBOX_TAG = "network_watchlist_report"; |
| |
| private final Context mContext; |
| private final @Nullable DropBoxManager mDropBoxManager; |
| private final ContentResolver mResolver; |
| private final PackageManager mPm; |
| private final WatchlistReportDbHelper mDbHelper; |
| private final WatchlistConfig mConfig; |
| private final WatchlistSettings mSettings; |
| // A cache for uid and apk digest mapping. |
| // As uid won't be reused until reboot, it's safe to assume uid is unique per signature and app. |
| // TODO: Use more efficient data structure. |
| private final ConcurrentHashMap<Integer, byte[]> mCachedUidDigestMap = |
| new ConcurrentHashMap<>(); |
| |
| private interface WatchlistEventKeys { |
| String HOST = "host"; |
| String IP_ADDRESSES = "ipAddresses"; |
| String UID = "uid"; |
| String TIMESTAMP = "timestamp"; |
| } |
| |
| WatchlistLoggingHandler(Context context, Looper looper) { |
| super(looper); |
| mContext = context; |
| mPm = mContext.getPackageManager(); |
| mResolver = mContext.getContentResolver(); |
| mDbHelper = WatchlistReportDbHelper.getInstance(context); |
| mConfig = WatchlistConfig.getInstance(); |
| mSettings = WatchlistSettings.getInstance(); |
| mDropBoxManager = mContext.getSystemService(DropBoxManager.class); |
| } |
| |
| @Override |
| public void handleMessage(Message msg) { |
| switch (msg.what) { |
| case LOG_WATCHLIST_EVENT_MSG: { |
| final Bundle data = msg.getData(); |
| handleNetworkEvent( |
| data.getString(WatchlistEventKeys.HOST), |
| data.getStringArray(WatchlistEventKeys.IP_ADDRESSES), |
| data.getInt(WatchlistEventKeys.UID), |
| data.getLong(WatchlistEventKeys.TIMESTAMP) |
| ); |
| break; |
| } |
| case REPORT_RECORDS_IF_NECESSARY_MSG: |
| tryAggregateRecords(); |
| break; |
| default: { |
| Slog.d(TAG, "WatchlistLoggingHandler received an unknown of message."); |
| break; |
| } |
| } |
| } |
| |
| /** |
| * Return if a given package has testOnly is true. |
| */ |
| private boolean isPackageTestOnly(int uid) { |
| final ApplicationInfo ai; |
| try { |
| final String[] packageNames = mPm.getPackagesForUid(uid); |
| if (packageNames == null || packageNames.length == 0) { |
| Slog.e(TAG, "Couldn't find package: " + packageNames); |
| return false; |
| } |
| ai = mPm.getApplicationInfo(packageNames[0],0); |
| } catch (NameNotFoundException e) { |
| // Should not happen. |
| return false; |
| } |
| return (ai.flags & ApplicationInfo.FLAG_TEST_ONLY) != 0; |
| } |
| |
| /** |
| * Report network watchlist records if we collected enough data. |
| */ |
| public void reportWatchlistIfNecessary() { |
| final Message msg = obtainMessage(REPORT_RECORDS_IF_NECESSARY_MSG); |
| sendMessage(msg); |
| } |
| |
| /** |
| * Insert network traffic event to watchlist async queue processor. |
| */ |
| public void asyncNetworkEvent(String host, String[] ipAddresses, int uid) { |
| final Message msg = obtainMessage(LOG_WATCHLIST_EVENT_MSG); |
| final Bundle bundle = new Bundle(); |
| bundle.putString(WatchlistEventKeys.HOST, host); |
| bundle.putStringArray(WatchlistEventKeys.IP_ADDRESSES, ipAddresses); |
| bundle.putInt(WatchlistEventKeys.UID, uid); |
| bundle.putLong(WatchlistEventKeys.TIMESTAMP, System.currentTimeMillis()); |
| msg.setData(bundle); |
| sendMessage(msg); |
| } |
| |
| private void handleNetworkEvent(String hostname, String[] ipAddresses, |
| int uid, long timestamp) { |
| if (DEBUG) { |
| Slog.i(TAG, "handleNetworkEvent with host: " + hostname + ", uid: " + uid); |
| } |
| final String cncDomain = searchAllSubDomainsInWatchlist(hostname); |
| if (cncDomain != null) { |
| insertRecord(uid, cncDomain, timestamp); |
| } else { |
| final String cncIp = searchIpInWatchlist(ipAddresses); |
| if (cncIp != null) { |
| insertRecord(uid, cncIp, timestamp); |
| } |
| } |
| } |
| |
| private boolean insertRecord(int uid, String cncHost, long timestamp) { |
| if (!mConfig.isConfigSecure() && !isPackageTestOnly(uid)) { |
| // Skip package if config is not secure and package is not TestOnly app. |
| return true; |
| } |
| final byte[] digest = getDigestFromUid(uid); |
| final boolean result = mDbHelper.insertNewRecord(digest, cncHost, timestamp); |
| tryAggregateRecords(); |
| return result; |
| } |
| |
| private boolean shouldReportNetworkWatchlist() { |
| final long lastReportTime = Settings.Global.getLong(mResolver, |
| Settings.Global.NETWORK_WATCHLIST_LAST_REPORT_TIME, 0L); |
| final long currentTimestamp = System.currentTimeMillis(); |
| if (currentTimestamp < lastReportTime) { |
| Slog.i(TAG, "Last report time is larger than current time, reset report"); |
| mDbHelper.cleanup(); |
| return false; |
| } |
| return currentTimestamp >= lastReportTime + ONE_DAY_MS; |
| } |
| |
| private void tryAggregateRecords() { |
| // Check if it's necessary to generate watchlist report now. |
| if (!shouldReportNetworkWatchlist()) { |
| Slog.i(TAG, "No need to aggregate record yet."); |
| return; |
| } |
| Slog.i(TAG, "Start aggregating watchlist records."); |
| if (mDropBoxManager != null && mDropBoxManager.isTagEnabled(DROPBOX_TAG)) { |
| Settings.Global.putLong(mResolver, |
| Settings.Global.NETWORK_WATCHLIST_LAST_REPORT_TIME, |
| System.currentTimeMillis()); |
| final WatchlistReportDbHelper.AggregatedResult aggregatedResult = |
| mDbHelper.getAggregatedRecords(); |
| if (aggregatedResult == null) { |
| Slog.i(TAG, "Cannot get result from database"); |
| return; |
| } |
| // Get all digests for watchlist report, it should include all installed |
| // application digests and previously recorded app digests. |
| final List<String> digestsForReport = getAllDigestsForReport(aggregatedResult); |
| final byte[] secretKey = mSettings.getPrivacySecretKey(); |
| final byte[] encodedResult = ReportEncoder.encodeWatchlistReport(mConfig, |
| secretKey, digestsForReport, aggregatedResult); |
| if (encodedResult != null) { |
| addEncodedReportToDropBox(encodedResult); |
| } |
| } |
| mDbHelper.cleanup(); |
| } |
| |
| /** |
| * Get all digests for watchlist report. |
| * It should include: |
| * (1) All installed app digests. We need this because we need to ensure after DP we don't know |
| * if an app is really visited C&C site. |
| * (2) App digests that previously recorded in database. |
| */ |
| private List<String> getAllDigestsForReport(WatchlistReportDbHelper.AggregatedResult record) { |
| // Step 1: Get all installed application digests. |
| final List<ApplicationInfo> apps = mContext.getPackageManager().getInstalledApplications( |
| PackageManager.MATCH_ANY_USER | PackageManager.MATCH_ALL); |
| final HashSet<String> result = new HashSet<>(apps.size() + record.appDigestCNCList.size()); |
| final int size = apps.size(); |
| for (int i = 0; i < size; i++) { |
| byte[] digest = getDigestFromUid(apps.get(i).uid); |
| result.add(HexDump.toHexString(digest)); |
| } |
| // Step 2: Add all digests from records |
| result.addAll(record.appDigestCNCList.keySet()); |
| return new ArrayList<>(result); |
| } |
| |
| private void addEncodedReportToDropBox(byte[] encodedReport) { |
| mDropBoxManager.addData(DROPBOX_TAG, encodedReport, 0); |
| } |
| |
| /** |
| * Get app digest from app uid. |
| * Return null if system cannot get digest from uid. |
| */ |
| @Nullable |
| private byte[] getDigestFromUid(int uid) { |
| return mCachedUidDigestMap.computeIfAbsent(uid, key -> { |
| final String[] packageNames = mPm.getPackagesForUid(key); |
| final int userId = UserHandle.getUserId(uid); |
| if (!ArrayUtils.isEmpty(packageNames)) { |
| for (String packageName : packageNames) { |
| try { |
| final String apkPath = mPm.getPackageInfoAsUser(packageName, |
| PackageManager.MATCH_DIRECT_BOOT_AWARE |
| | PackageManager.MATCH_DIRECT_BOOT_UNAWARE, userId) |
| .applicationInfo.publicSourceDir; |
| if (TextUtils.isEmpty(apkPath)) { |
| Slog.w(TAG, "Cannot find apkPath for " + packageName); |
| continue; |
| } |
| return DigestUtils.getSha256Hash(new File(apkPath)); |
| } catch (NameNotFoundException | NoSuchAlgorithmException | IOException e) { |
| Slog.e(TAG, "Should not happen", e); |
| return null; |
| } |
| } |
| } else { |
| Slog.e(TAG, "Should not happen"); |
| } |
| return null; |
| }); |
| } |
| |
| /** |
| * Search if any ip addresses are in watchlist. |
| * |
| * @param ipAddresses Ip address that you want to search in watchlist. |
| * @return Ip address that exists in watchlist, null if it does not match anything. |
| */ |
| private String searchIpInWatchlist(String[] ipAddresses) { |
| for (String ipAddress : ipAddresses) { |
| if (isIpInWatchlist(ipAddress)) { |
| return ipAddress; |
| } |
| } |
| return null; |
| } |
| |
| /** Search if the ip is in watchlist */ |
| private boolean isIpInWatchlist(String ipAddr) { |
| if (ipAddr == null) { |
| return false; |
| } |
| return mConfig.containsIp(ipAddr); |
| } |
| |
| /** Search if the host is in watchlist */ |
| private boolean isHostInWatchlist(String host) { |
| if (host == null) { |
| return false; |
| } |
| return mConfig.containsDomain(host); |
| } |
| |
| /** |
| * Search if any sub-domain in host is in watchlist. |
| * |
| * @param host Host that we want to search. |
| * @return Domain that exists in watchlist, null if it does not match anything. |
| */ |
| private String searchAllSubDomainsInWatchlist(String host) { |
| if (host == null) { |
| return null; |
| } |
| final String[] subDomains = getAllSubDomains(host); |
| for (String subDomain : subDomains) { |
| if (isHostInWatchlist(subDomain)) { |
| return subDomain; |
| } |
| } |
| return null; |
| } |
| |
| /** Get all sub-domains in a host */ |
| @VisibleForTesting |
| static String[] getAllSubDomains(String host) { |
| if (host == null) { |
| return null; |
| } |
| final ArrayList<String> subDomainList = new ArrayList<>(); |
| subDomainList.add(host); |
| int index = host.indexOf("."); |
| while (index != -1) { |
| host = host.substring(index + 1); |
| if (!TextUtils.isEmpty(host)) { |
| subDomainList.add(host); |
| } |
| index = host.indexOf("."); |
| } |
| return subDomainList.toArray(new String[0]); |
| } |
| } |