| /* |
| * Copyright (C) 2013 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.firewall; |
| |
| import android.app.AppGlobals; |
| import android.content.ComponentName; |
| import android.content.Intent; |
| import android.content.IntentFilter; |
| import android.content.pm.ActivityInfo; |
| import android.content.pm.ApplicationInfo; |
| import android.content.pm.IPackageManager; |
| import android.content.pm.PackageManager; |
| import android.os.Environment; |
| import android.os.FileObserver; |
| import android.os.Handler; |
| import android.os.Message; |
| import android.os.RemoteException; |
| import android.util.Slog; |
| import android.util.Xml; |
| import com.android.internal.util.XmlUtils; |
| import com.android.server.EventLogTags; |
| import com.android.server.IntentResolver; |
| import org.xmlpull.v1.XmlPullParser; |
| import org.xmlpull.v1.XmlPullParserException; |
| |
| import java.io.File; |
| import java.io.FileInputStream; |
| import java.io.FileNotFoundException; |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.List; |
| |
| public class IntentFirewall { |
| private static final String TAG = "IntentFirewall"; |
| |
| // e.g. /data/system/ifw/ifw.xml or /data/secure/system/ifw/ifw.xml |
| private static final File RULES_FILE = |
| new File(Environment.getSystemSecureDirectory(), "ifw/ifw.xml"); |
| |
| private static final int LOG_PACKAGES_MAX_LENGTH = 150; |
| private static final int LOG_PACKAGES_SUFFICIENT_LENGTH = 125; |
| |
| private static final String TAG_RULES = "rules"; |
| private static final String TAG_ACTIVITY = "activity"; |
| private static final String TAG_SERVICE = "service"; |
| private static final String TAG_BROADCAST = "broadcast"; |
| |
| private static final int TYPE_ACTIVITY = 0; |
| private static final int TYPE_BROADCAST = 1; |
| private static final int TYPE_SERVICE = 2; |
| |
| private static final HashMap<String, FilterFactory> factoryMap; |
| |
| private final AMSInterface mAms; |
| |
| private final RuleObserver mObserver; |
| |
| private FirewallIntentResolver mActivityResolver = new FirewallIntentResolver(); |
| private FirewallIntentResolver mBroadcastResolver = new FirewallIntentResolver(); |
| private FirewallIntentResolver mServiceResolver = new FirewallIntentResolver(); |
| |
| static { |
| FilterFactory[] factories = new FilterFactory[] { |
| AndFilter.FACTORY, |
| OrFilter.FACTORY, |
| NotFilter.FACTORY, |
| |
| StringFilter.ACTION, |
| StringFilter.COMPONENT, |
| StringFilter.COMPONENT_NAME, |
| StringFilter.COMPONENT_PACKAGE, |
| StringFilter.DATA, |
| StringFilter.HOST, |
| StringFilter.MIME_TYPE, |
| StringFilter.PATH, |
| StringFilter.SSP, |
| |
| CategoryFilter.FACTORY, |
| SenderFilter.FACTORY, |
| SenderPermissionFilter.FACTORY, |
| PortFilter.FACTORY |
| }; |
| |
| // load factor ~= .75 |
| factoryMap = new HashMap<String, FilterFactory>(factories.length * 4 / 3); |
| for (int i=0; i<factories.length; i++) { |
| FilterFactory factory = factories[i]; |
| factoryMap.put(factory.getTagName(), factory); |
| } |
| } |
| |
| public IntentFirewall(AMSInterface ams) { |
| mAms = ams; |
| File rulesFile = getRulesFile(); |
| rulesFile.getParentFile().mkdirs(); |
| |
| readRules(rulesFile); |
| |
| mObserver = new RuleObserver(rulesFile); |
| mObserver.startWatching(); |
| } |
| |
| /** |
| * This is called from ActivityManager to check if a start activity intent should be allowed. |
| * It is assumed the caller is already holding the global ActivityManagerService lock. |
| */ |
| public boolean checkStartActivity(Intent intent, ApplicationInfo callerApp, int callerUid, |
| int callerPid, String resolvedType, ActivityInfo resolvedActivity) { |
| List<Rule> matchingRules = mActivityResolver.queryIntent(intent, resolvedType, false, 0); |
| boolean log = false; |
| boolean block = false; |
| |
| for (int i=0; i< matchingRules.size(); i++) { |
| Rule rule = matchingRules.get(i); |
| if (rule.matches(this, intent, callerApp, callerUid, callerPid, resolvedType, |
| resolvedActivity.applicationInfo)) { |
| block |= rule.getBlock(); |
| log |= rule.getLog(); |
| |
| // if we've already determined that we should both block and log, there's no need |
| // to continue trying rules |
| if (block && log) { |
| break; |
| } |
| } |
| } |
| |
| if (log) { |
| logIntent(TYPE_ACTIVITY, intent, callerUid, resolvedType); |
| } |
| |
| return !block; |
| } |
| |
| private static void logIntent(int intentType, Intent intent, int callerUid, |
| String resolvedType) { |
| // The component shouldn't be null, but let's double check just to be safe |
| ComponentName cn = intent.getComponent(); |
| String shortComponent = null; |
| if (cn != null) { |
| shortComponent = cn.flattenToShortString(); |
| } |
| |
| String callerPackages = null; |
| int callerPackageCount = 0; |
| IPackageManager pm = AppGlobals.getPackageManager(); |
| if (pm != null) { |
| try { |
| String[] callerPackagesArray = pm.getPackagesForUid(callerUid); |
| if (callerPackagesArray != null) { |
| callerPackageCount = callerPackagesArray.length; |
| callerPackages = joinPackages(callerPackagesArray); |
| } |
| } catch (RemoteException ex) { |
| Slog.e(TAG, "Remote exception while retrieving packages", ex); |
| } |
| } |
| |
| EventLogTags.writeIfwIntentMatched(intentType, shortComponent, callerUid, |
| callerPackageCount, callerPackages, intent.getAction(), resolvedType, |
| intent.getDataString(), intent.getFlags()); |
| } |
| |
| /** |
| * Joins a list of package names such that the resulting string is no more than |
| * LOG_PACKAGES_MAX_LENGTH. |
| * |
| * Only full package names will be added to the result, unless every package is longer than the |
| * limit, in which case one of the packages will be truncated and added. In this case, an |
| * additional '-' character will be added to the end of the string, to denote the truncation. |
| * |
| * If it encounters a package that won't fit in the remaining space, it will continue on to the |
| * next package, unless the total length of the built string so far is greater than |
| * LOG_PACKAGES_SUFFICIENT_LENGTH, in which case it will stop and return what it has. |
| */ |
| private static String joinPackages(String[] packages) { |
| boolean first = true; |
| StringBuilder sb = new StringBuilder(); |
| for (int i=0; i<packages.length; i++) { |
| String pkg = packages[i]; |
| |
| // + 1 length for the comma. This logic technically isn't correct for the first entry, |
| // but it's not critical. |
| if (sb.length() + pkg.length() + 1 < LOG_PACKAGES_MAX_LENGTH) { |
| if (!first) { |
| sb.append(','); |
| } else { |
| first = false; |
| } |
| sb.append(pkg); |
| } else if (sb.length() >= LOG_PACKAGES_SUFFICIENT_LENGTH) { |
| return sb.toString(); |
| } |
| } |
| if (sb.length() == 0 && packages.length > 0) { |
| String pkg = packages[0]; |
| // truncating from the end - the last part of the package name is more likely to be |
| // interesting/unique |
| return pkg.substring(pkg.length() - LOG_PACKAGES_MAX_LENGTH + 1) + '-'; |
| } |
| return null; |
| } |
| |
| public static File getRulesFile() { |
| return RULES_FILE; |
| } |
| |
| /** |
| * Reads rules from the given file and replaces our set of rules with the newly read rules |
| * |
| * All calls to this method from the file observer come through a handler and are inherently |
| * serialized |
| */ |
| private void readRules(File rulesFile) { |
| FirewallIntentResolver[] resolvers = new FirewallIntentResolver[3]; |
| for (int i=0; i<resolvers.length; i++) { |
| resolvers[i] = new FirewallIntentResolver(); |
| } |
| |
| FileInputStream fis; |
| try { |
| fis = new FileInputStream(rulesFile); |
| } catch (FileNotFoundException ex) { |
| // Nope, no rules. Nothing else to do! |
| return; |
| } |
| |
| try { |
| XmlPullParser parser = Xml.newPullParser(); |
| |
| parser.setInput(fis, null); |
| |
| XmlUtils.beginDocument(parser, TAG_RULES); |
| |
| int[] numRules = new int[3]; |
| |
| int outerDepth = parser.getDepth(); |
| while (XmlUtils.nextElementWithin(parser, outerDepth)) { |
| int ruleType = -1; |
| |
| String tagName = parser.getName(); |
| if (tagName.equals(TAG_ACTIVITY)) { |
| ruleType = TYPE_ACTIVITY; |
| } else if (tagName.equals(TAG_BROADCAST)) { |
| ruleType = TYPE_BROADCAST; |
| } else if (tagName.equals(TAG_SERVICE)) { |
| ruleType = TYPE_SERVICE; |
| } |
| |
| if (ruleType != -1) { |
| Rule rule = new Rule(); |
| |
| FirewallIntentResolver resolver = resolvers[ruleType]; |
| |
| // if we get an error while parsing a particular rule, we'll just ignore |
| // that rule and continue on with the next rule |
| try { |
| rule.readFromXml(parser); |
| } catch (XmlPullParserException ex) { |
| Slog.e(TAG, "Error reading intent firewall rule", ex); |
| continue; |
| } |
| |
| numRules[ruleType]++; |
| |
| for (int i=0; i<rule.getIntentFilterCount(); i++) { |
| resolver.addFilter(rule.getIntentFilter(i)); |
| } |
| } |
| } |
| |
| Slog.i(TAG, "Read new rules (A:" + numRules[TYPE_ACTIVITY] + |
| " B:" + numRules[TYPE_BROADCAST] + " S:" + numRules[TYPE_SERVICE] + ")"); |
| |
| synchronized (mAms.getAMSLock()) { |
| mActivityResolver = resolvers[TYPE_ACTIVITY]; |
| mBroadcastResolver = resolvers[TYPE_BROADCAST]; |
| mServiceResolver = resolvers[TYPE_SERVICE]; |
| } |
| } catch (XmlPullParserException ex) { |
| // if there was an error outside of a specific rule, then there are probably |
| // structural problems with the xml file, and we should completely ignore it |
| Slog.e(TAG, "Error reading intent firewall rules", ex); |
| clearRules(); |
| } catch (IOException ex) { |
| Slog.e(TAG, "Error reading intent firewall rules", ex); |
| clearRules(); |
| } finally { |
| try { |
| fis.close(); |
| } catch (IOException ex) { |
| Slog.e(TAG, "Error while closing " + rulesFile, ex); |
| } |
| } |
| } |
| |
| /** |
| * Clears out all of our rules |
| * |
| * All calls to this method from the file observer come through a handler and are inherently |
| * serialized |
| */ |
| private void clearRules() { |
| Slog.i(TAG, "Clearing all rules"); |
| |
| synchronized (mAms.getAMSLock()) { |
| mActivityResolver = new FirewallIntentResolver(); |
| mBroadcastResolver = new FirewallIntentResolver(); |
| mServiceResolver = new FirewallIntentResolver(); |
| } |
| } |
| |
| static Filter parseFilter(XmlPullParser parser) throws IOException, XmlPullParserException { |
| String elementName = parser.getName(); |
| |
| FilterFactory factory = factoryMap.get(elementName); |
| |
| if (factory == null) { |
| throw new XmlPullParserException("Unknown element in filter list: " + elementName); |
| } |
| return factory.newFilter(parser); |
| } |
| |
| private static class Rule extends AndFilter { |
| private static final String TAG_INTENT_FILTER = "intent-filter"; |
| |
| private static final String ATTR_BLOCK = "block"; |
| private static final String ATTR_LOG = "log"; |
| |
| private final ArrayList<FirewallIntentFilter> mIntentFilters = |
| new ArrayList<FirewallIntentFilter>(1); |
| private boolean block; |
| private boolean log; |
| |
| @Override |
| public Rule readFromXml(XmlPullParser parser) throws IOException, XmlPullParserException { |
| block = Boolean.parseBoolean(parser.getAttributeValue(null, ATTR_BLOCK)); |
| log = Boolean.parseBoolean(parser.getAttributeValue(null, ATTR_LOG)); |
| |
| super.readFromXml(parser); |
| return this; |
| } |
| |
| @Override |
| protected void readChild(XmlPullParser parser) throws IOException, XmlPullParserException { |
| if (parser.getName().equals(TAG_INTENT_FILTER)) { |
| FirewallIntentFilter intentFilter = new FirewallIntentFilter(this); |
| intentFilter.readFromXml(parser); |
| mIntentFilters.add(intentFilter); |
| } else { |
| super.readChild(parser); |
| } |
| } |
| |
| public int getIntentFilterCount() { |
| return mIntentFilters.size(); |
| } |
| |
| public FirewallIntentFilter getIntentFilter(int index) { |
| return mIntentFilters.get(index); |
| } |
| |
| public boolean getBlock() { |
| return block; |
| } |
| |
| public boolean getLog() { |
| return log; |
| } |
| } |
| |
| private static class FirewallIntentFilter extends IntentFilter { |
| private final Rule rule; |
| |
| public FirewallIntentFilter(Rule rule) { |
| this.rule = rule; |
| } |
| } |
| |
| private static class FirewallIntentResolver |
| extends IntentResolver<FirewallIntentFilter, Rule> { |
| @Override |
| protected boolean allowFilterResult(FirewallIntentFilter filter, List<Rule> dest) { |
| return !dest.contains(filter.rule); |
| } |
| |
| @Override |
| protected boolean isPackageForFilter(String packageName, FirewallIntentFilter filter) { |
| return true; |
| } |
| |
| @Override |
| protected FirewallIntentFilter[] newArray(int size) { |
| return new FirewallIntentFilter[size]; |
| } |
| |
| @Override |
| protected Rule newResult(FirewallIntentFilter filter, int match, int userId) { |
| return filter.rule; |
| } |
| |
| @Override |
| protected void sortResults(List<Rule> results) { |
| // there's no need to sort the results |
| return; |
| } |
| } |
| |
| private static final int READ_RULES = 0; |
| private static final int CLEAR_RULES = 1; |
| |
| final Handler mHandler = new Handler() { |
| @Override |
| public void handleMessage(Message msg) { |
| switch (msg.what) { |
| case READ_RULES: |
| readRules(getRulesFile()); |
| break; |
| case CLEAR_RULES: |
| clearRules(); |
| break; |
| } |
| } |
| }; |
| |
| /** |
| * Monitors for the creation/deletion/modification of the rule file |
| */ |
| private class RuleObserver extends FileObserver { |
| // The file name we're monitoring, with no path component |
| private final String mMonitoredFile; |
| |
| private static final int CREATED_FLAGS = FileObserver.CREATE|FileObserver.MOVED_TO| |
| FileObserver.CLOSE_WRITE; |
| private static final int DELETED_FLAGS = FileObserver.DELETE|FileObserver.MOVED_FROM; |
| |
| public RuleObserver(File monitoredFile) { |
| super(monitoredFile.getParentFile().getAbsolutePath(), CREATED_FLAGS|DELETED_FLAGS); |
| mMonitoredFile = monitoredFile.getName(); |
| } |
| |
| @Override |
| public void onEvent(int event, String path) { |
| if (path.equals(mMonitoredFile)) { |
| // we wait 250ms before taking any action on an event, in order to dedup multiple |
| // events. E.g. a delete event followed by a create event followed by a subsequent |
| // write+close event; |
| if ((event & CREATED_FLAGS) != 0) { |
| mHandler.removeMessages(READ_RULES); |
| mHandler.removeMessages(CLEAR_RULES); |
| mHandler.sendEmptyMessageDelayed(READ_RULES, 250); |
| } else if ((event & DELETED_FLAGS) != 0) { |
| mHandler.removeMessages(READ_RULES); |
| mHandler.removeMessages(CLEAR_RULES); |
| mHandler.sendEmptyMessageDelayed(CLEAR_RULES, 250); |
| } |
| } |
| } |
| } |
| |
| /** |
| * This interface contains the methods we need from ActivityManagerService. This allows AMS to |
| * export these methods to us without making them public, and also makes it easier to test this |
| * component. |
| */ |
| public interface AMSInterface { |
| int checkComponentPermission(String permission, int pid, int uid, |
| int owningUid, boolean exported); |
| Object getAMSLock(); |
| } |
| |
| /** |
| * Checks if the caller has access to a component |
| * |
| * @param permission If present, the caller must have this permission |
| * @param pid The pid of the caller |
| * @param uid The uid of the caller |
| * @param owningUid The uid of the application that owns the component |
| * @param exported Whether the component is exported |
| * @return True if the caller can access the described component |
| */ |
| boolean checkComponentPermission(String permission, int pid, int uid, int owningUid, |
| boolean exported) { |
| return mAms.checkComponentPermission(permission, pid, uid, owningUid, exported) == |
| PackageManager.PERMISSION_GRANTED; |
| } |
| |
| boolean signaturesMatch(int uid1, int uid2) { |
| try { |
| IPackageManager pm = AppGlobals.getPackageManager(); |
| return pm.checkUidSignatures(uid1, uid2) == PackageManager.SIGNATURE_MATCH; |
| } catch (RemoteException ex) { |
| Slog.e(TAG, "Remote exception while checking signatures", ex); |
| return false; |
| } |
| } |
| } |