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Application restrictions proxy code
Bug: 26111675 Change-Id: I4355c43178f9567ece9c83f195777c649359b4e4
1 parent ddbef0a commit 7080ac7

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‎app/src/main/AndroidManifest.xml‎

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android:resource="@xml/filepaths" />
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</provider>
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<service android:name=".profilepolicy.apprestrictions.AppRestrictionsProxy">
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<intent-filter>
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<action android:name="com.android.vending.dpc.APPLICATION_RESTRICTIONS_PROXY" />
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</intent-filter>
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</service>
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</application>
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</manifest>

‎app/src/main/java/com/afwsamples/testdpc/profilepolicy/apprestrictions/AppRestrictionsProxy.java‎

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/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.afwsamples.testdpc.profilepolicy.apprestrictions;
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import android.app.Service;
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import android.app.admin.DevicePolicyManager;
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import android.content.ComponentName;
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import android.content.Intent;
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import android.os.Bundle;
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import android.os.IBinder;
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import android.os.Messenger;
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import com.afwsamples.testdpc.DeviceAdminReceiver;
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/**
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* Before N, only the DPC has permission to set application restrictions via
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* {@link DevicePolicyManager#setApplicationRestrictions(ComponentName, String, Bundle)}.
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*
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* To enable the another package to manage the application restrictions, a bound service is used to
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* pass them to {@link AppRestrictionsProxy}.
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*
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* From N onwards, a given package can be granted permission to manage application restrictions,
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* which removes the need for the proxy code.
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*/
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public class AppRestrictionsProxy extends Service {
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private final Messenger mMessenger = new Messenger(new AppRestrictionsProxyHandler(this,
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DeviceAdminReceiver.getComponentName(this)));
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@Override
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public IBinder onBind(Intent intent) {
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return mMessenger.getBinder();
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}
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}

‎app/src/main/java/com/afwsamples/testdpc/profilepolicy/apprestrictions/AppRestrictionsProxyHandler.java‎

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/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.afwsamples.testdpc.profilepolicy.apprestrictions;
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import android.app.admin.DevicePolicyManager;
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import android.content.ComponentName;
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import android.content.Context;
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import android.content.pm.PackageInfo;
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import android.content.pm.PackageManager;
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import android.content.pm.PackageManager.NameNotFoundException;
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import android.content.pm.Signature;
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import android.os.Bundle;
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import android.os.Handler;
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import android.os.Message;
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import android.os.RemoteException;
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import android.preference.PreferenceManager;
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import android.util.Log;
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import java.util.ArrayList;
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import java.util.HashSet;
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import java.util.List;
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import java.util.Set;
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/**
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* Handles the message passed from another package to set the application restrictions.
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*
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* The package name must be provided, along with the application restrictions bundle to set.
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* To clear the application restrictions, an empty bundle should be passed.
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*/
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public class AppRestrictionsProxyHandler extends Handler {
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private static final String TAG = "AppRestrictionsProxy";
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private static final int MSG_SET_APPLICATION_RESTRICTIONS = 1;
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private static final int MSG_CAN_SET_APPLICATION_RESTRICTIONS = 2;
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private static final int MSG_GET_APPLICATION_RESTRICTIONS = 3;
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private static final String APPLICATION_RESTRICTIONS_MANAGING_PACKAGE_SIGNATURES_KEY =
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"application_restrictions_managing_package_signatures";
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private static final String APPLICATION_RESTRICTIONS_MANAGING_PACKAGE_KEY =
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"application_restrictions_managing_package";
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public static final String KEY_APPLICATION_RESTRICTIONS = "applicationRestrictions";
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public static final String KEY_PACKAGE_NAME = "packageName";
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public static final String KEY_CAN_SET_APPLICATION_RESTRICTIONS
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= "canSetApplicationRestrictions";
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private final Context mContext;
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private final ComponentName mAdmin;
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public AppRestrictionsProxyHandler(Context context, ComponentName admin) {
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mContext = context;
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mAdmin = admin;
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}
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@Override
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public void handleMessage(Message msg) {
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switch (msg.what) {
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case MSG_SET_APPLICATION_RESTRICTIONS: {
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ensureCallerSignature(msg.sendingUid);
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String packageName = msg.getData().getString(KEY_PACKAGE_NAME);
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Bundle appRestrictions = msg.getData().getBundle(KEY_APPLICATION_RESTRICTIONS);
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setApplicationRestrictions(packageName, appRestrictions);
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break;
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}
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case MSG_CAN_SET_APPLICATION_RESTRICTIONS: {
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String callingPackage = mContext.getPackageManager().getNameForUid(msg.sendingUid);
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String managingPackage = getApplicationRestrictionsManagingPackage();
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Bundle responseBundle = new Bundle();
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responseBundle.putBoolean(KEY_CAN_SET_APPLICATION_RESTRICTIONS,
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callingPackage != null && callingPackage.equals(managingPackage));
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Message response = Message.obtain();
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response.setData(responseBundle);
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try {
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msg.replyTo.send(response);
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} catch (RemoteException e) {
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Log.e(TAG, "Unable to respond to canSetApplicationRestrictions.", e);
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}
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break;
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}
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case MSG_GET_APPLICATION_RESTRICTIONS: {
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ensureCallerSignature(msg.sendingUid);
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String packageName = msg.getData().getString(KEY_PACKAGE_NAME);
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Bundle appRestrictions = getApplicationRestrictions(packageName);
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Bundle responseBundle = new Bundle();
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responseBundle.putBundle(KEY_APPLICATION_RESTRICTIONS, appRestrictions);
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Message response = Message.obtain();
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response.setData(responseBundle);
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try {
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msg.replyTo.send(response);
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} catch (RemoteException e) {
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Log.e(TAG, "Unable to respond to getApplicationRestrictions.", e);
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}
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break;
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}
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default:
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throw new IllegalArgumentException("Unknown 'what': " + msg.what);
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}
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}
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/**
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* Called by a profile owner or device owner to grant permission to a package to manage
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* application restrictions for the calling user via the {@link AppRestrictionsProxy}.
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*
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* This permission is persistent until it is later cleared by calling this method with a
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* {@code null} value.
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*
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* The supplied application restriction managing package must be installed when calling this
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* API, otherwise an {@link IllegalArgumentException} will be thrown.
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*/
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public void setApplicationRestrictionsManagingPackage(String packageName) {
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if (packageName == null) {
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PreferenceManager.getDefaultSharedPreferences(mContext).edit()
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.putStringSet(APPLICATION_RESTRICTIONS_MANAGING_PACKAGE_SIGNATURES_KEY, null);
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PreferenceManager.getDefaultSharedPreferences(mContext).edit()
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.putString(APPLICATION_RESTRICTIONS_MANAGING_PACKAGE_KEY, null);
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return;
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}
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Signature[] signatures;
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try {
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PackageManager packageManager = mContext.getPackageManager();
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PackageInfo packageInfo =
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packageManager.getPackageInfo(packageName, PackageManager.GET_SIGNATURES);
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if (packageInfo == null) {
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throw new IllegalArgumentException("Package info could not be retrieved for " +
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"package " + packageName + ".");
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}
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signatures = packageInfo.signatures;
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if (signatures == null) {
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throw new IllegalArgumentException("Package info did not contain signatures " +
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"for package " + packageName + ".");
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}
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} catch (NameNotFoundException e) {
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throw new IllegalArgumentException("Cannot set " + packageName + " as application " +
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"restriction managing package as it is not installed.", e);
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}
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Set<String> signatureSet = new HashSet<>();
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for (Signature signature : signatures) {
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signatureSet.add(signature.toCharsString());
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}
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PreferenceManager.getDefaultSharedPreferences(mContext).edit()
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.putStringSet(APPLICATION_RESTRICTIONS_MANAGING_PACKAGE_SIGNATURES_KEY,
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signatureSet);
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PreferenceManager.getDefaultSharedPreferences(mContext).edit()
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.putString(APPLICATION_RESTRICTIONS_MANAGING_PACKAGE_KEY, packageName);
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}
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/**
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* Called by a profile owner or device owner to retrieve the application restrictions managing
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* package for the current user, or {@code null} if none is set.
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*/
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public String getApplicationRestrictionsManagingPackage(){
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return PreferenceManager.getDefaultSharedPreferences(mContext)
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.getString(APPLICATION_RESTRICTIONS_MANAGING_PACKAGE_KEY, null);
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}
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private void setApplicationRestrictions(String packageName, Bundle appRestrictions){
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if (packageName == null) {
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throw new IllegalArgumentException("packageName cannot be null.");
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}
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if (appRestrictions == null) {
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throw new IllegalArgumentException("applicationRestrictions bundle " +
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"cannot be null.");
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}
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Log.d(TAG, "Setting application restrictions for package " + packageName);
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DevicePolicyManager devicePolicyManager = (DevicePolicyManager)
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mContext.getSystemService(Context.DEVICE_POLICY_SERVICE);
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devicePolicyManager.setApplicationRestrictions(mAdmin, packageName,
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appRestrictions);
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}
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private Bundle getApplicationRestrictions(String packageName){
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if (packageName == null) {
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throw new IllegalArgumentException("packageName cannot be null.");
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}
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DevicePolicyManager devicePolicyManager = (DevicePolicyManager)
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mContext.getSystemService(Context.DEVICE_POLICY_SERVICE);
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return devicePolicyManager.getApplicationRestrictions(mAdmin, packageName);
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}
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/**
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* Checks that the message sent through the bound service was sent by the same package as
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* declared in {@link #setApplicationRestrictionsManagingPackage(String)}, and
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* that its signature has not changed since it was set.
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*
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* @param callerUid the UID of the caller
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*
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* @throws SecurityException if the DPC hasn't given permission to the caller to manage
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* application restrictions, or if the calling package's signature has changed since it was
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* set.
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*/
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private void ensureCallerSignature(int callerUid) {
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String appRestrictionsManagingPackage = getApplicationRestrictionsManagingPackage();
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if (appRestrictionsManagingPackage == null) {
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throw new SecurityException("Caller is not app restrictions managing package");
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}
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PackageManager packageManager = mContext.getPackageManager();
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String callingPackageName = packageManager.getNameForUid(callerUid);
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if (!appRestrictionsManagingPackage.equals(callingPackageName)) {
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throw new SecurityException("Caller is not app restrictions managing package");
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}
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Set<String> storedSignatures = PreferenceManager.getDefaultSharedPreferences(mContext)
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.getStringSet(APPLICATION_RESTRICTIONS_MANAGING_PACKAGE_SIGNATURES_KEY, null);
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if (storedSignatures == null) {
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throw new IllegalStateException(
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"App restrictions managing package signatures have not been stored.");
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}
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Signature[] callingPackageSignatures;
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try {
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PackageInfo packageInfo = packageManager
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.getPackageInfo(callingPackageName, PackageManager.GET_SIGNATURES);
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if (packageInfo == null) {
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throw new IllegalArgumentException("Package info could not be retrieved for " +
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"package " + callingPackageName + ".");
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}
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callingPackageSignatures = packageInfo.signatures;
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if (callingPackageSignatures == null) {
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throw new IllegalArgumentException("Package info did not contain signatures " +
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"for package " + callingPackageName + ".");
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}
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} catch (NameNotFoundException e) {
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throw new SecurityException(e);
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}
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List<Signature> expectedSignatures = new ArrayList<>(storedSignatures.size());
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for (String signatureString : storedSignatures) {
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expectedSignatures.add(new Signature(signatureString));
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}
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for (Signature callingSignature : callingPackageSignatures) {
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for (Signature expectedSignature : expectedSignatures) {
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if (expectedSignature.equals(callingSignature)) {
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return;
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}
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}
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}
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throw new SecurityException("Calling package signature doesn't match");
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}
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}

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