/**
* Copyright (C) 2014 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 android.service.trust;
import android.Manifest;
import android.annotation.IntDef;
import android.annotation.SdkConstant;
import android.annotation.SystemApi;
import android.app.Service;
import android.app.admin.DevicePolicyManager;
import android.content.ComponentName;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ServiceInfo;
import android.os.Handler;
import android.os.IBinder;
import android.os.PersistableBundle;
import android.os.RemoteException;
import android.util.Log;
import android.util.Slog;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.List;
/**
* A service that notifies the system about whether it believes the environment of the device
* to be trusted.
*
* <p>Trust agents may only be provided by the platform. It is expected that there is only
* one trust agent installed on the platform. In the event there is more than one,
* either trust agent can enable trust.
* </p>
*
* <p>To extend this class, you must declare the service in your manifest file with
* the {@link android.Manifest.permission#BIND_TRUST_AGENT} permission
* and include an intent filter with the {@link #SERVICE_INTERFACE} action. For example:</p>
* <pre>
* <service android:name=".TrustAgent"
* android:label="@string/service_name"
* android:permission="android.permission.BIND_TRUST_AGENT">
* <intent-filter>
* <action android:name="android.service.trust.TrustAgentService" />
* </intent-filter>
* <meta-data android:name="android.service.trust.trustagent"
* android:value="@xml/trust_agent" />
* </service></pre>
*
* <p>The associated meta-data file can specify an activity that is accessible through Settings
* and should allow configuring the trust agent, as defined in
* {@link android.R.styleable#TrustAgent}. For example:</p>
*
* <pre>
* <trust-agent xmlns:android="http://schemas.android.com/apk/res/android"
* android:settingsActivity=".TrustAgentSettings" /></pre>
*
* @hide
*/
@SystemApi
public class TrustAgentService extends Service {
private final String TAG = TrustAgentService.class.getSimpleName() +
"[" + getClass().getSimpleName() + "]";
private static final boolean DEBUG = false;
/**
* The {@link Intent} that must be declared as handled by the service.
*/
@SdkConstant(SdkConstant.SdkConstantType.SERVICE_ACTION)
public static final String SERVICE_INTERFACE
= "android.service.trust.TrustAgentService";
/**
* The name of the {@code meta-data} tag pointing to additional configuration of the trust
* agent.
*/
public static final String TRUST_AGENT_META_DATA = "android.service.trust.trustagent";
/**
* Flag for {@link #grantTrust(CharSequence, long, int)} indicating that trust is being granted
* as the direct result of user action - such as solving a security challenge. The hint is used
* by the system to optimize the experience. Behavior may vary by device and release, so
* one should only set this parameter if it meets the above criteria rather than relying on
* the behavior of any particular device or release.
*/
public static final int FLAG_GRANT_TRUST_INITIATED_BY_USER = 1 << 0;
/**
* Flag for {@link #grantTrust(CharSequence, long, int)} indicating that the agent would like
* to dismiss the keyguard. When using this flag, the {@code TrustAgentService} must ensure
* it is only set in response to a direct user action with the expectation of dismissing the
* keyguard.
*/
public static final int FLAG_GRANT_TRUST_DISMISS_KEYGUARD = 1 << 1;
/** @hide */
@Retention(RetentionPolicy.SOURCE)
@IntDef(flag = true,
value = {
FLAG_GRANT_TRUST_INITIATED_BY_USER,
FLAG_GRANT_TRUST_DISMISS_KEYGUARD,
})
public @interface GrantTrustFlags {}
private static final int MSG_UNLOCK_ATTEMPT = 1;
private static final int MSG_CONFIGURE = 2;
private static final int MSG_TRUST_TIMEOUT = 3;
private static final int MSG_DEVICE_LOCKED = 4;
private static final int MSG_DEVICE_UNLOCKED = 5;
/**
* Class containing raw data for a given configuration request.
*/
private static final class ConfigurationData {
final IBinder token;
final List<PersistableBundle> options;
ConfigurationData(List<PersistableBundle> opts, IBinder t) {
options = opts;
token = t;
}
}
private ITrustAgentServiceCallback mCallback;
private Runnable mPendingGrantTrustTask;
private boolean mManagingTrust;
// Lock used to access mPendingGrantTrustTask and mCallback.
private final Object mLock = new Object();
private Handler mHandler = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case MSG_UNLOCK_ATTEMPT:
onUnlockAttempt(msg.arg1 != 0);
break;
case MSG_CONFIGURE:
ConfigurationData data = (ConfigurationData) msg.obj;
boolean result = onConfigure(data.options);
if (data.token != null) {
try {
synchronized (mLock) {
mCallback.onConfigureCompleted(result, data.token);
}
} catch (RemoteException e) {
onError("calling onSetTrustAgentFeaturesEnabledCompleted()");
}
}
break;
case MSG_TRUST_TIMEOUT:
onTrustTimeout();
break;
case MSG_DEVICE_LOCKED:
onDeviceLocked();
break;
case MSG_DEVICE_UNLOCKED:
onDeviceUnlocked();
break;
}
}
};
@Override
public void onCreate() {
super.onCreate();
ComponentName component = new ComponentName(this, getClass());
try {
ServiceInfo serviceInfo = getPackageManager().getServiceInfo(component, 0 /* flags */);
if (!Manifest.permission.BIND_TRUST_AGENT.equals(serviceInfo.permission)) {
throw new IllegalStateException(component.flattenToShortString()
+ " is not declared with the permission "
+ "\"" + Manifest.permission.BIND_TRUST_AGENT + "\"");
}
} catch (PackageManager.NameNotFoundException e) {
Log.e(TAG, "Can't get ServiceInfo for " + component.toShortString());
}
}
/**
* Called after the user attempts to authenticate in keyguard with their device credentials,
* such as pin, pattern or password.
*
* @param successful true if the user successfully completed the challenge.
*/
public void onUnlockAttempt(boolean successful) {
}
/**
* Called when the timeout provided by the agent expires. Note that this may be called earlier
* than requested by the agent if the trust timeout is adjusted by the system or
* {@link DevicePolicyManager}. The agent is expected to re-evaluate the trust state and only
* call {@link #grantTrust(CharSequence, long, boolean)} if the trust state should be
* continued.
*/
public void onTrustTimeout() {
}
/**
* Called when the device enters a state where a PIN, pattern or
* password must be entered to unlock it.
*/
public void onDeviceLocked() {
}
/**
* Called when the device leaves a state where a PIN, pattern or
* password must be entered to unlock it.
*/
public void onDeviceUnlocked() {
}
private void onError(String msg) {
Slog.v(TAG, "Remote exception while " + msg);
}
/**
* Called when device policy admin wants to enable specific options for agent in response to
* {@link DevicePolicyManager#setKeyguardDisabledFeatures(ComponentName, int)} and
* {@link DevicePolicyManager#setTrustAgentConfiguration(ComponentName, ComponentName,
* PersistableBundle)}.
* <p>Agents that support configuration options should overload this method and return 'true'.
*
* @param options The aggregated list of options or an empty list if no restrictions apply.
* @return true if the {@link TrustAgentService} supports configuration options.
*/
public boolean onConfigure(List<PersistableBundle> options) {
return false;
}
/**
* Call to grant trust on the device.
*
* @param message describes why the device is trusted, e.g. "Trusted by location".
* @param durationMs amount of time in milliseconds to keep the device in a trusted state.
* Trust for this agent will automatically be revoked when the timeout expires unless
* extended by a subsequent call to this function. The timeout is measured from the
* invocation of this function as dictated by {@link SystemClock#elapsedRealtime())}.
* For security reasons, the value should be no larger than necessary.
* The value may be adjusted by the system as necessary to comply with a policy controlled
* by the system or {@link DevicePolicyManager} restrictions. See {@link #onTrustTimeout()}
* for determining when trust expires.
* @param initiatedByUser this is a hint to the system that trust is being granted as the
* direct result of user action - such as solving a security challenge. The hint is used
* by the system to optimize the experience. Behavior may vary by device and release, so
* one should only set this parameter if it meets the above criteria rather than relying on
* the behavior of any particular device or release. Corresponds to
* {@link #FLAG_GRANT_TRUST_INITIATED_BY_USER}.
* @throws IllegalStateException if the agent is not currently managing trust.
*
* @deprecated use {@link #grantTrust(CharSequence, long, int)} instead.
*/
@Deprecated
public final void grantTrust(
final CharSequence message, final long durationMs, final boolean initiatedByUser) {
grantTrust(message, durationMs, initiatedByUser ? FLAG_GRANT_TRUST_INITIATED_BY_USER : 0);
}
/**
* Call to grant trust on the device.
*
* @param message describes why the device is trusted, e.g. "Trusted by location".
* @param durationMs amount of time in milliseconds to keep the device in a trusted state.
* Trust for this agent will automatically be revoked when the timeout expires unless
* extended by a subsequent call to this function. The timeout is measured from the
* invocation of this function as dictated by {@link SystemClock#elapsedRealtime())}.
* For security reasons, the value should be no larger than necessary.
* The value may be adjusted by the system as necessary to comply with a policy controlled
* by the system or {@link DevicePolicyManager} restrictions. See {@link #onTrustTimeout()}
* for determining when trust expires.
* @param flags TBDocumented
* @throws IllegalStateException if the agent is not currently managing trust.
*/
public final void grantTrust(
final CharSequence message, final long durationMs, @GrantTrustFlags final int flags) {
synchronized (mLock) {
if (!mManagingTrust) {
throw new IllegalStateException("Cannot grant trust if agent is not managing trust."
+ " Call setManagingTrust(true) first.");
}
if (mCallback != null) {
try {
mCallback.grantTrust(message.toString(), durationMs, flags);
} catch (RemoteException e) {
onError("calling enableTrust()");
}
} else {
// Remember trust has been granted so we can effectively grant it once the service
// is bound.
mPendingGrantTrustTask = new Runnable() {
@Override
public void run() {
grantTrust(message, durationMs, flags);
}
};
}
}
}
/**
* Call to revoke trust on the device.
*/
public final void revokeTrust() {
synchronized (mLock) {
if (mPendingGrantTrustTask != null) {
mPendingGrantTrustTask = null;
}
if (mCallback != null) {
try {
mCallback.revokeTrust();
} catch (RemoteException e) {
onError("calling revokeTrust()");
}
}
}
}
/**
* Call to notify the system if the agent is ready to manage trust.
*
* This property is not persistent across recreating the service and defaults to false.
* Therefore this method is typically called when initializing the agent in {@link #onCreate}.
*
* @param managingTrust indicates if the agent would like to manage trust.
*/
public final void setManagingTrust(boolean managingTrust) {
synchronized (mLock) {
if (mManagingTrust != managingTrust) {
mManagingTrust = managingTrust;
if (mCallback != null) {
try {
mCallback.setManagingTrust(managingTrust);
} catch (RemoteException e) {
onError("calling setManagingTrust()");
}
}
}
}
}
@Override
public final IBinder onBind(Intent intent) {
if (DEBUG) Slog.v(TAG, "onBind() intent = " + intent);
return new TrustAgentServiceWrapper();
}
private final class TrustAgentServiceWrapper extends ITrustAgentService.Stub {
@Override /* Binder API */
public void onUnlockAttempt(boolean successful) {
mHandler.obtainMessage(MSG_UNLOCK_ATTEMPT, successful ? 1 : 0, 0).sendToTarget();
}
@Override /* Binder API */
public void onTrustTimeout() {
mHandler.sendEmptyMessage(MSG_TRUST_TIMEOUT);
}
@Override /* Binder API */
public void onConfigure(List<PersistableBundle> args, IBinder token) {
mHandler.obtainMessage(MSG_CONFIGURE, new ConfigurationData(args, token))
.sendToTarget();
}
@Override
public void onDeviceLocked() throws RemoteException {
mHandler.obtainMessage(MSG_DEVICE_LOCKED).sendToTarget();
}
@Override
public void onDeviceUnlocked() throws RemoteException {
mHandler.obtainMessage(MSG_DEVICE_UNLOCKED).sendToTarget();
}
@Override /* Binder API */
public void setCallback(ITrustAgentServiceCallback callback) {
synchronized (mLock) {
mCallback = callback;
// The managingTrust property is false implicitly on the server-side, so we only
// need to set it here if the agent has decided to manage trust.
if (mManagingTrust) {
try {
mCallback.setManagingTrust(mManagingTrust);
} catch (RemoteException e ) {
onError("calling setManagingTrust()");
}
}
if (mPendingGrantTrustTask != null) {
mPendingGrantTrustTask.run();
mPendingGrantTrustTask = null;
}
}
}
}
}