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/*
* Copyright (C) 2015 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.tools.lint.checks;
import static com.android.SdkConstants.ANDROID_URI;
import static com.android.SdkConstants.ATTR_NAME;
import static com.android.SdkConstants.ATTR_PERMISSION;
import static com.android.SdkConstants.CLASS_BROADCASTRECEIVER;
import static com.android.SdkConstants.CLASS_CONTEXT;
import static com.android.SdkConstants.CLASS_INTENT;
import static com.android.SdkConstants.TAG_INTENT_FILTER;
import static com.android.SdkConstants.TAG_RECEIVER;
import com.android.annotations.NonNull;
import com.android.annotations.Nullable;
import com.android.annotations.VisibleForTesting;
import com.android.tools.lint.client.api.JavaParser.ResolvedClass;
import com.android.tools.lint.client.api.JavaParser.ResolvedMethod;
import com.android.tools.lint.client.api.JavaParser.ResolvedNode;
import com.android.tools.lint.client.api.JavaParser.ResolvedVariable;
import com.android.tools.lint.detector.api.Category;
import com.android.tools.lint.detector.api.Detector;
import com.android.tools.lint.detector.api.Detector.JavaScanner;
import com.android.tools.lint.detector.api.Detector.XmlScanner;
import com.android.tools.lint.detector.api.Implementation;
import com.android.tools.lint.detector.api.Issue;
import com.android.tools.lint.detector.api.JavaContext;
import com.android.tools.lint.detector.api.LintUtils;
import com.android.tools.lint.detector.api.Location;
import com.android.tools.lint.detector.api.Scope;
import com.android.tools.lint.detector.api.Severity;
import com.android.tools.lint.detector.api.XmlContext;
import com.google.common.collect.Sets;
import org.w3c.dom.Element;
import java.util.Collection;
import java.util.Collections;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import lombok.ast.ClassDeclaration;
import lombok.ast.ForwardingAstVisitor;
import lombok.ast.MethodDeclaration;
import lombok.ast.MethodInvocation;
import lombok.ast.Node;
import lombok.ast.VariableReference;
public class UnsafeBroadcastReceiverDetector extends Detector
implements JavaScanner, XmlScanner {
/* Description of check implementations:
*
* UnsafeProtectedBroadcastReceiver check
*
* If a receiver is declared in the application manifest that has an intent-filter
* with an action string that matches a protected-broadcast action string,
* then if that receiver has an onReceive method, ensure that the method calls
* getAction at least once.
*
* With this check alone, false positives will occur if the onReceive method
* passes the received intent to another method that calls getAction.
* We look for any calls to aload_2 within the method bytecode, which could
* indicate loading the inputted intent onto the stack to use in a call
* to another method. In those cases, still report the issue, but
* report in the description that the finding may be a false positive.
* An alternative implementation option would be to omit reporting the issue
* at all when a call to aload_2 exists.
*
* UnprotectedSMSBroadcastReceiver check
*
* If a receiver is declared in AndroidManifest that has an intent-filter
* with action string SMS_DELIVER or SMS_RECEIVED, ensure that the
* receiver requires callers to have the BROADCAST_SMS permission.
*
* It is possible that the receiver may check the sender's permission by
* calling checkCallingPermission, which could cause a false positive.
* However, application developers should still be encouraged to declare
* the permission requirement in the manifest where it can be easily
* audited.
*
* Future work: Add checks for other action strings that should require
* particular permissions be checked, such as
* android.provider.Telephony.WAP_PUSH_DELIVER
*
* Note that neither of these checks address receivers dynamically created at runtime,
* only ones that are declared in the application manifest.
*/
public static final Issue ACTION_STRING = Issue.create(
"UnsafeProtectedBroadcastReceiver",
"Unsafe Protected BroadcastReceiver",
"BroadcastReceivers that declare an intent-filter for a protected-broadcast action " +
"string must check that the received intent's action string matches the expected " +
"value, otherwise it is possible for malicious actors to spoof intents.",
Category.SECURITY,
6,
Severity.WARNING,
new Implementation(UnsafeBroadcastReceiverDetector.class,
EnumSet.of(Scope.MANIFEST, Scope.JAVA_FILE)));
public static final Issue BROADCAST_SMS = Issue.create(
"UnprotectedSMSBroadcastReceiver",
"Unprotected SMS BroadcastReceiver",
"BroadcastReceivers that declare an intent-filter for SMS_DELIVER or " +
"SMS_RECEIVED must ensure that the caller has the BROADCAST_SMS permission, " +
"otherwise it is possible for malicious actors to spoof intents.",
Category.SECURITY,
6,
Severity.WARNING,
new Implementation(UnsafeBroadcastReceiverDetector.class,
Scope.MANIFEST_SCOPE));
/* List of protected broadcast strings. This list must be sorted alphabetically.
* Protected broadcast strings are defined by entries in the
* manifest of system-level components or applications.
* The below list is copied from frameworks/base/core/res/AndroidManifest.xml
* and packages/services/Telephony/AndroidManifest.xml .
* It should be periodically updated. This list will likely not be complete, since
* protected-broadcast entries can be defined elsewhere, but should address
* most situations.
*/
@VisibleForTesting
static final String[] PROTECTED_BROADCASTS = new String[] {
"android.app.action.DEVICE_OWNER_CHANGED",
"android.app.action.ENTER_CAR_MODE",
"android.app.action.ENTER_DESK_MODE",
"android.app.action.EXIT_CAR_MODE",
"android.app.action.EXIT_DESK_MODE",
"android.app.action.NEXT_ALARM_CLOCK_CHANGED",
"android.app.action.SYSTEM_UPDATE_POLICY_CHANGED",
"android.appwidget.action.APPWIDGET_DELETED",
"android.appwidget.action.APPWIDGET_DISABLED",
"android.appwidget.action.APPWIDGET_ENABLED",
"android.appwidget.action.APPWIDGET_HOST_RESTORED",
"android.appwidget.action.APPWIDGET_RESTORED",
"android.appwidget.action.APPWIDGET_UPDATE_OPTIONS",
"android.backup.intent.CLEAR",
"android.backup.intent.INIT",
"android.backup.intent.RUN",
"android.bluetooth.a2dp-sink.profile.action.AUDIO_CONFIG_CHANGED",
"android.bluetooth.a2dp-sink.profile.action.CONNECTION_STATE_CHANGED",
"android.bluetooth.a2dp-sink.profile.action.PLAYING_STATE_CHANGED",
"android.bluetooth.a2dp.profile.action.CONNECTION_STATE_CHANGED",
"android.bluetooth.a2dp.profile.action.PLAYING_STATE_CHANGED",
"android.bluetooth.adapter.action.CONNECTION_STATE_CHANGED",
"android.bluetooth.adapter.action.DISCOVERY_FINISHED",
"android.bluetooth.adapter.action.DISCOVERY_STARTED",
"android.bluetooth.adapter.action.LOCAL_NAME_CHANGED",
"android.bluetooth.adapter.action.SCAN_MODE_CHANGED",
"android.bluetooth.adapter.action.STATE_CHANGED",
"android.bluetooth.avrcp-controller.profile.action.CONNECTION_STATE_CHANGED",
"android.bluetooth.device.action.ACL_CONNECTED",
"android.bluetooth.device.action.ACL_DISCONNECTED",
"android.bluetooth.device.action.ACL_DISCONNECT_REQUESTED",
"android.bluetooth.device.action.ALIAS_CHANGED",
"android.bluetooth.device.action.BOND_STATE_CHANGED",
"android.bluetooth.device.action.CLASS_CHANGED",
"android.bluetooth.device.action.CONNECTION_ACCESS_CANCEL",
"android.bluetooth.device.action.CONNECTION_ACCESS_REPLY",
"android.bluetooth.device.action.CONNECTION_ACCESS_REQUEST",
"android.bluetooth.device.action.DISAPPEARED",
"android.bluetooth.device.action.FOUND",
"android.bluetooth.device.action.MAS_INSTANCE",
"android.bluetooth.device.action.NAME_CHANGED",
"android.bluetooth.device.action.NAME_FAILED",
"android.bluetooth.device.action.PAIRING_CANCEL",
"android.bluetooth.device.action.PAIRING_REQUEST",
"android.bluetooth.device.action.UUID",
"android.bluetooth.devicepicker.action.DEVICE_SELECTED",
"android.bluetooth.devicepicker.action.LAUNCH",
"android.bluetooth.headset.action.VENDOR_SPECIFIC_HEADSET_EVENT",
"android.bluetooth.headset.profile.action.AUDIO_STATE_CHANGED",
"android.bluetooth.headset.profile.action.CONNECTION_STATE_CHANGED",
"android.bluetooth.headsetclient.profile.action.AG_CALL_CHANGED",
"android.bluetooth.headsetclient.profile.action.AG_EVENT",
"android.bluetooth.headsetclient.profile.action.AUDIO_STATE_CHANGED",
"android.bluetooth.headsetclient.profile.action.CONNECTION_STATE_CHANGED",
"android.bluetooth.headsetclient.profile.action.LAST_VTAG",
"android.bluetooth.headsetclient.profile.action.RESULT",
"android.bluetooth.input.profile.action.CONNECTION_STATE_CHANGED",
"android.bluetooth.input.profile.action.PROTOCOL_MODE_CHANGED",
"android.bluetooth.input.profile.action.VIRTUAL_UNPLUG_STATUS",
"android.bluetooth.pan.profile.action.CONNECTION_STATE_CHANGED",
"android.bluetooth.pbap.intent.action.PBAP_STATE_CHANGED",
"android.btopp.intent.action.CONFIRM",
"android.btopp.intent.action.HIDE",
"android.btopp.intent.action.HIDE_COMPLETE",
"android.btopp.intent.action.INCOMING_FILE_NOTIFICATION",
"android.btopp.intent.action.LIST",
"android.btopp.intent.action.OPEN",
"android.btopp.intent.action.OPEN_INBOUND",
"android.btopp.intent.action.OPEN_OUTBOUND",
"android.btopp.intent.action.RETRY",
"android.btopp.intent.action.USER_CONFIRMATION_TIMEOUT",
"android.hardware.display.action.WIFI_DISPLAY_STATUS_CHANGED",
"android.hardware.usb.action.USB_ACCESSORY_ATTACHED",
"android.hardware.usb.action.USB_ACCESSORY_DETACHED",
"android.hardware.usb.action.USB_DEVICE_ATTACHED",
"android.hardware.usb.action.USB_DEVICE_DETACHED",
"android.hardware.usb.action.USB_PORT_CHANGED",
"android.hardware.usb.action.USB_STATE",
"android.intent.action.ACTION_DEFAULT_DATA_SUBSCRIPTION_CHANGED",
"android.intent.action.ACTION_DEFAULT_SMS_SUBSCRIPTION_CHANGED",
"android.intent.action.ACTION_DEFAULT_SUBSCRIPTION_CHANGED",
"android.intent.action.ACTION_DEFAULT_VOICE_SUBSCRIPTION_CHANGED",
"android.intent.action.ACTION_IDLE_MAINTENANCE_END",
"android.intent.action.ACTION_IDLE_MAINTENANCE_START",
"android.intent.action.ACTION_POWER_CONNECTED",
"android.intent.action.ACTION_POWER_DISCONNECTED",
"android.intent.action.ACTION_SET_RADIO_CAPABILITY_DONE",
"android.intent.action.ACTION_SET_RADIO_CAPABILITY_FAILED",
"android.intent.action.ACTION_SHUTDOWN",
"android.intent.action.ACTION_SUBINFO_CONTENT_CHANGE",
"android.intent.action.ACTION_SUBINFO_RECORD_UPDATED",
"android.intent.action.ADVANCED_SETTINGS",
"android.intent.action.AIRPLANE_MODE",
"android.intent.action.ANY_DATA_STATE",
"android.intent.action.APPLICATION_RESTRICTIONS_CHANGED",
"android.intent.action.BATTERY_CHANGED",
"android.intent.action.BATTERY_LOW",
"android.intent.action.BATTERY_OKAY",
"android.intent.action.BOOT_COMPLETED",
"android.intent.action.BUGREPORT_FINISHED",
"android.intent.action.CHARGING",
"android.intent.action.CLEAR_DNS_CACHE",
"android.intent.action.CONFIGURATION_CHANGED",
"android.intent.action.DATE_CHANGED",
"android.intent.action.DEVICE_STORAGE_FULL",
"android.intent.action.DEVICE_STORAGE_LOW",
"android.intent.action.DEVICE_STORAGE_NOT_FULL",
"android.intent.action.DEVICE_STORAGE_OK",
"android.intent.action.DISCHARGING",
"android.intent.action.DOCK_EVENT",
"android.intent.action.DREAMING_STARTED",
"android.intent.action.DREAMING_STOPPED",
"android.intent.action.EXTERNAL_APPLICATIONS_AVAILABLE",
"android.intent.action.EXTERNAL_APPLICATIONS_UNAVAILABLE",
"android.intent.action.HDMI_PLUGGED",
"android.intent.action.HEADSET_PLUG",
"android.intent.action.INTENT_FILTER_NEEDS_VERIFICATION",
"android.intent.action.LOCALE_CHANGED",
"android.intent.action.MASTER_CLEAR_NOTIFICATION",
"android.intent.action.MEDIA_BAD_REMOVAL",
"android.intent.action.MEDIA_CHECKING",
"android.intent.action.MEDIA_EJECT",
"android.intent.action.MEDIA_MOUNTED",
"android.intent.action.MEDIA_NOFS",
"android.intent.action.MEDIA_REMOVED",
"android.intent.action.MEDIA_SHARED",
"android.intent.action.MEDIA_UNMOUNTABLE",
"android.intent.action.MEDIA_UNMOUNTED",
"android.intent.action.MEDIA_UNSHARED",
"android.intent.action.MY_PACKAGE_REPLACED",
"android.intent.action.NEW_OUTGOING_CALL",
"android.intent.action.PACKAGE_ADDED",
"android.intent.action.PACKAGE_CHANGED",
"android.intent.action.PACKAGE_DATA_CLEARED",
"android.intent.action.PACKAGE_FIRST_LAUNCH",
"android.intent.action.PACKAGE_FULLY_REMOVED",
"android.intent.action.PACKAGE_INSTALL",
"android.intent.action.PACKAGE_NEEDS_VERIFICATION",
"android.intent.action.PACKAGE_REMOVED",
"android.intent.action.PACKAGE_REPLACED",
"android.intent.action.PACKAGE_RESTARTED",
"android.intent.action.PACKAGE_VERIFIED",
"android.intent.action.PERMISSION_RESPONSE_RECEIVED",
"android.intent.action.PHONE_STATE",
"android.intent.action.PROXY_CHANGE",
"android.intent.action.QUERY_PACKAGE_RESTART",
"android.intent.action.REBOOT",
"android.intent.action.REQUEST_PERMISSION",
"android.intent.action.SCREEN_OFF",
"android.intent.action.SCREEN_ON",
"android.intent.action.SUB_DEFAULT_CHANGED",
"android.intent.action.THERMAL_EVENT",
"android.intent.action.TIMEZONE_CHANGED",
"android.intent.action.TIME_SET",
"android.intent.action.TIME_TICK",
"android.intent.action.UID_REMOVED",
"android.intent.action.USER_ADDED",
"android.intent.action.USER_BACKGROUND",
"android.intent.action.USER_FOREGROUND",
"android.intent.action.USER_PRESENT",
"android.intent.action.USER_REMOVED",
"android.intent.action.USER_STARTED",
"android.intent.action.USER_STARTING",
"android.intent.action.USER_STOPPED",
"android.intent.action.USER_STOPPING",
"android.intent.action.USER_SWITCHED",
"android.internal.policy.action.BURN_IN_PROTECTION",
"android.location.GPS_ENABLED_CHANGE",
"android.location.GPS_FIX_CHANGE",
"android.location.MODE_CHANGED",
"android.location.PROVIDERS_CHANGED",
"android.media.ACTION_SCO_AUDIO_STATE_UPDATED",
"android.media.AUDIO_BECOMING_NOISY",
"android.media.MASTER_MUTE_CHANGED_ACTION",
"android.media.MASTER_VOLUME_CHANGED_ACTION",
"android.media.RINGER_MODE_CHANGED",
"android.media.SCO_AUDIO_STATE_CHANGED",
"android.media.VIBRATE_SETTING_CHANGED",
"android.media.VOLUME_CHANGED_ACTION",
"android.media.action.HDMI_AUDIO_PLUG",
"android.net.ConnectivityService.action.PKT_CNT_SAMPLE_INTERVAL_ELAPSED",
"android.net.conn.BACKGROUND_DATA_SETTING_CHANGED",
"android.net.conn.CAPTIVE_PORTAL",
"android.net.conn.CAPTIVE_PORTAL_TEST_COMPLETED",
"android.net.conn.CONNECTIVITY_CHANGE",
"android.net.conn.CONNECTIVITY_CHANGE_IMMEDIATE",
"android.net.conn.DATA_ACTIVITY_CHANGE",
"android.net.conn.INET_CONDITION_ACTION",
"android.net.conn.NETWORK_CONDITIONS_MEASURED",
"android.net.conn.TETHER_STATE_CHANGED",
"android.net.nsd.STATE_CHANGED",
"android.net.proxy.PAC_REFRESH",
"android.net.scoring.SCORER_CHANGED",
"android.net.scoring.SCORE_NETWORKS",
"android.net.wifi.CONFIGURED_NETWORKS_CHANGE",
"android.net.wifi.LINK_CONFIGURATION_CHANGED",
"android.net.wifi.RSSI_CHANGED",
"android.net.wifi.SCAN_RESULTS",
"android.net.wifi.STATE_CHANGE",
"android.net.wifi.WIFI_AP_STATE_CHANGED",
"android.net.wifi.WIFI_CREDENTIAL_CHANGED",
"android.net.wifi.WIFI_SCAN_AVAILABLE",
"android.net.wifi.WIFI_STATE_CHANGED",
"android.net.wifi.p2p.CONNECTION_STATE_CHANGE",
"android.net.wifi.p2p.DISCOVERY_STATE_CHANGE",
"android.net.wifi.p2p.PEERS_CHANGED",
"android.net.wifi.p2p.PERSISTENT_GROUPS_CHANGED",
"android.net.wifi.p2p.STATE_CHANGED",
"android.net.wifi.p2p.THIS_DEVICE_CHANGED",
"android.net.wifi.supplicant.CONNECTION_CHANGE",
"android.net.wifi.supplicant.STATE_CHANGE",
"android.nfc.action.LLCP_LINK_STATE_CHANGED",
"android.nfc.action.TRANSACTION_DETECTED",
"android.nfc.handover.intent.action.HANDOVER_STARTED",
"android.nfc.handover.intent.action.TRANSFER_DONE",
"android.nfc.handover.intent.action.TRANSFER_PROGRESS",
"android.os.UpdateLock.UPDATE_LOCK_CHANGED",
"android.os.action.DEVICE_IDLE_MODE_CHANGED",
"android.os.action.POWER_SAVE_MODE_CHANGED",
"android.os.action.POWER_SAVE_MODE_CHANGING",
"android.os.action.POWER_SAVE_TEMP_WHITELIST_CHANGED",
"android.os.action.POWER_SAVE_WHITELIST_CHANGED",
"android.os.action.SCREEN_BRIGHTNESS_BOOST_CHANGED",
"android.os.action.SETTING_RESTORED",
"android.telecom.action.DEFAULT_DIALER_CHANGED",
"com.android.bluetooth.pbap.authcancelled",
"com.android.bluetooth.pbap.authchall",
"com.android.bluetooth.pbap.authresponse",
"com.android.bluetooth.pbap.userconfirmtimeout",
"com.android.nfc_extras.action.AID_SELECTED",
"com.android.nfc_extras.action.RF_FIELD_OFF_DETECTED",
"com.android.nfc_extras.action.RF_FIELD_ON_DETECTED",
"com.android.server.WifiManager.action.DELAYED_DRIVER_STOP",
"com.android.server.WifiManager.action.START_PNO",
"com.android.server.WifiManager.action.START_SCAN",
"com.android.server.connectivityservice.CONNECTED_TO_PROVISIONING_NETWORK_ACTION",
};
private static final Set PROTECTED_BROADCAST_SET =
Sets.newHashSet(PROTECTED_BROADCASTS);
private Set mReceiversWithProtectedBroadcastIntentFilter = new HashSet();
public UnsafeBroadcastReceiverDetector() {
}
// ---- Implements XmlScanner ----
@Override
public Collection getApplicableElements() {
return Collections.singletonList(TAG_RECEIVER);
}
@Override
public void visitElement(@NonNull XmlContext context,
@NonNull Element element) {
String tag = element.getTagName();
if (TAG_RECEIVER.equals(tag)) {
String name = element.getAttributeNS(ANDROID_URI, ATTR_NAME);
String permission = element.getAttributeNS(ANDROID_URI, ATTR_PERMISSION);
// If no permission attribute, then if any exists at the application
// element, it applies
if (permission == null || permission.isEmpty()) {
Element parent = (Element) element.getParentNode();
permission = parent.getAttributeNS(ANDROID_URI, ATTR_PERMISSION);
}
List children = LintUtils.getChildren(element);
for (Element child : children) {
String tagName = child.getTagName();
if (TAG_INTENT_FILTER.equals(tagName)) {
if (name.startsWith(".")) {
name = context.getProject().getPackage() + name;
}
name = name.replace('$', '.');
List children2 = LintUtils.getChildren(child);
for (Element child2 : children2) {
if ("action".equals(child2.getTagName())) {
String actionName = child2.getAttributeNS(
ANDROID_URI, ATTR_NAME);
if (("android.provider.Telephony.SMS_DELIVER".equals(actionName) ||
"android.provider.Telephony.SMS_RECEIVED".
equals(actionName)) &&
!"android.permission.BROADCAST_SMS".equals(permission)) {
context.report(
BROADCAST_SMS,
element,
context.getLocation(element),
"BroadcastReceivers that declare an intent-filter for " +
"SMS_DELIVER or SMS_RECEIVED must ensure that the " +
"caller has the BROADCAST_SMS permission, otherwise it " +
"is possible for malicious actors to spoof intents.");
}
else if (PROTECTED_BROADCAST_SET.contains(actionName)) {
mReceiversWithProtectedBroadcastIntentFilter.add(name);
}
}
}
break;
}
}
}
}
// ---- Implements JavaScanner ----
@Nullable
@Override
public List applicableSuperClasses() {
return mReceiversWithProtectedBroadcastIntentFilter.isEmpty()
? null : Collections.singletonList(CLASS_BROADCASTRECEIVER);
}
@Override
public void checkClass(@NonNull JavaContext context, @Nullable ClassDeclaration node,
@NonNull Node declarationOrAnonymous, @NonNull ResolvedClass cls) {
if (node == null) { // anonymous classes can't be the ones referenced in the manifest
return;
}
String name = cls.getName();
if (!mReceiversWithProtectedBroadcastIntentFilter.contains(name)) {
return;
}
for (Node member : node.astBody().astMembers()) {
if (member instanceof MethodDeclaration) {
MethodDeclaration declaration = (MethodDeclaration)member;
if ("onReceive".equals(declaration.astMethodName().astValue())
&& declaration.astParameters().size() == 2) {
ResolvedNode resolved = context.resolve(declaration);
if (resolved instanceof ResolvedMethod) {
ResolvedMethod method = (ResolvedMethod) resolved;
if (method.getArgumentCount() == 2
&& method.getArgumentType(0).matchesName(CLASS_CONTEXT)
&& method.getArgumentType(1).matchesName(CLASS_INTENT)) {
checkOnReceive(context, declaration, method);
break;
}
}
}
}
}
}
private static void checkOnReceive(@NonNull JavaContext context,
@NonNull MethodDeclaration declaration,
@NonNull ResolvedMethod method) {
// Search for call to getAction but also search for references to aload_2,
// which indicates that the method is making use of the received intent in
// some way.
//
// If the onReceive method doesn't call getAction but does make use of
// the received intent, it is possible that it is passing it to another
// method that might be performing the getAction check, so we warn that the
// finding may be a false positive. (An alternative option would be to not
// report a finding at all in this case.)
assert method.getArgumentCount() == 2;
ResolvedVariable parameter = null;
if (declaration.astParameters().size() == 2) {
ResolvedNode resolved = context.resolve(declaration.astParameters().last());
if (resolved instanceof ResolvedVariable) {
parameter = (ResolvedVariable) resolved;
}
}
OnReceiveVisitor visitor = new OnReceiveVisitor(context, parameter);
declaration.accept(visitor);
if (!visitor.getCallsGetAction()) {
String report;
if (!visitor.getUsesIntent()) {
report = "This broadcast receiver declares an intent-filter for a protected " +
"broadcast action string, which can only be sent by the system, " +
"not third-party applications. However, the receiver's onReceive " +
"method does not appear to call getAction to ensure that the " +
"received Intent's action string matches the expected value, " +
"potentially making it possible for another actor to send a " +
"spoofed intent with no action string or a different action " +
"string and cause undesired behavior.";
} else {
// An alternative implementation option is to not report a finding at all in
// this case, if we are worried about false positives causing confusion or
// resulting in developers ignoring other lint warnings.
report = "This broadcast receiver declares an intent-filter for a protected " +
"broadcast action string, which can only be sent by the system, " +
"not third-party applications. However, the receiver's onReceive " +
"method does not appear to call getAction to ensure that the " +
"received Intent's action string matches the expected value, " +
"potentially making it possible for another actor to send a " +
"spoofed intent with no action string or a different action " +
"string and cause undesired behavior. In this case, it is " +
"possible that the onReceive method passed the received Intent " +
"to another method that checked the action string. If so, this " +
"finding can safely be ignored.";
}
Location location = context.getNameLocation(declaration);
context.report(ACTION_STRING, declaration, location, report);
}
}
private static class OnReceiveVisitor extends ForwardingAstVisitor {
@NonNull private final JavaContext mContext;
@Nullable private final ResolvedVariable mParameter;
private boolean mCallsGetAction;
private boolean mUsesIntent;
public OnReceiveVisitor(@NonNull JavaContext context, @Nullable ResolvedVariable parameter) {
mContext = context;
mParameter = parameter;
}
public boolean getCallsGetAction() {
return mCallsGetAction;
}
public boolean getUsesIntent() {
return mUsesIntent;
}
@Override
public boolean visitMethodInvocation(@NonNull MethodInvocation node) {
if (!mCallsGetAction) {
ResolvedNode resolved = mContext.resolve(node);
if (resolved instanceof ResolvedMethod) {
ResolvedMethod method = (ResolvedMethod) resolved;
if (method.getName().equals("getAction") &&
method.getContainingClass().isSubclassOf(CLASS_INTENT, false)) {
mCallsGetAction = true;
}
}
}
return super.visitMethodInvocation(node);
}
@Override
public boolean visitVariableReference(@NonNull VariableReference node) {
if (!mUsesIntent && mParameter != null) {
ResolvedNode resolved = mContext.resolve(node);
if (mParameter.equals(resolved)) {
mUsesIntent = true;
}
}
return super.visitVariableReference(node);
}
}
}
