1 /*
2  * Copyright (C) 2014 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License
15  */
16 
17 package android.net;
18 
19 import android.Manifest;
20 import android.Manifest.permission;
21 import android.annotation.Nullable;
22 import android.app.AppOpsManager;
23 import android.content.Context;
24 import android.content.Intent;
25 import android.content.pm.ActivityInfo;
26 import android.content.pm.ApplicationInfo;
27 import android.content.pm.PackageManager;
28 import android.content.pm.ResolveInfo;
29 import android.os.UserHandle;
30 import android.provider.Settings;
31 import android.text.TextUtils;
32 import android.util.Log;
33 
34 import java.util.ArrayList;
35 import java.util.Collection;
36 import java.util.List;
37 
38 /**
39  * Internal class for managing the primary network scorer application.
40  *
41  * TODO: Rename this to something more generic.
42  *
43  * @hide
44  */
45 public final class NetworkScorerAppManager {
46     private static final String TAG = "NetworkScorerAppManager";
47 
48     private static final Intent SCORE_INTENT =
49             new Intent(NetworkScoreManager.ACTION_SCORE_NETWORKS);
50 
51     /** This class cannot be instantiated. */
NetworkScorerAppManager()52     private NetworkScorerAppManager() {}
53 
54     public static class NetworkScorerAppData {
55         /** Package name of this scorer app. */
56         public final String mPackageName;
57 
58         /** UID of the scorer app. */
59         public final int mPackageUid;
60 
61         /** Name of this scorer app for display. */
62         public final CharSequence mScorerName;
63 
64         /**
65          * Optional class name of a configuration activity. Null if none is set.
66          *
67          * @see NetworkScoreManager#ACTION_CUSTOM_ENABLE
68          */
69         public final String mConfigurationActivityClassName;
70 
NetworkScorerAppData(String packageName, int packageUid, CharSequence scorerName, @Nullable String configurationActivityClassName)71         public NetworkScorerAppData(String packageName, int packageUid, CharSequence scorerName,
72                 @Nullable String configurationActivityClassName) {
73             mScorerName = scorerName;
74             mPackageName = packageName;
75             mPackageUid = packageUid;
76             mConfigurationActivityClassName = configurationActivityClassName;
77         }
78     }
79 
80     /**
81      * Returns the list of available scorer apps.
82      *
83      * <p>A network scorer is any application which:
84      * <ul>
85      * <li>Declares the {@link android.Manifest.permission#SCORE_NETWORKS} permission.
86      * <li>Includes a receiver for {@link NetworkScoreManager#ACTION_SCORE_NETWORKS} guarded by the
87      *     {@link android.Manifest.permission#BROADCAST_NETWORK_PRIVILEGED} permission.
88      * </ul>
89      *
90      * @return the list of scorers, or the empty list if there are no valid scorers.
91      */
getAllValidScorers(Context context)92     public static Collection<NetworkScorerAppData> getAllValidScorers(Context context) {
93         List<NetworkScorerAppData> scorers = new ArrayList<>();
94 
95         PackageManager pm = context.getPackageManager();
96         // Only apps installed under the primary user of the device can be scorers.
97         List<ResolveInfo> receivers =
98                 pm.queryBroadcastReceivers(SCORE_INTENT, 0 /* flags */, UserHandle.USER_OWNER);
99         for (ResolveInfo receiver : receivers) {
100             // This field is a misnomer, see android.content.pm.ResolveInfo#activityInfo
101             final ActivityInfo receiverInfo = receiver.activityInfo;
102             if (receiverInfo == null) {
103                 // Should never happen with queryBroadcastReceivers, but invalid nonetheless.
104                 continue;
105             }
106             if (!permission.BROADCAST_NETWORK_PRIVILEGED.equals(receiverInfo.permission)) {
107                 // Receiver doesn't require the BROADCAST_NETWORK_PRIVILEGED permission, which means
108                 // anyone could trigger network scoring and flood the framework with score requests.
109                 continue;
110             }
111             if (pm.checkPermission(permission.SCORE_NETWORKS, receiverInfo.packageName) !=
112                     PackageManager.PERMISSION_GRANTED) {
113                 // Application doesn't hold the SCORE_NETWORKS permission, so the user never
114                 // approved it as a network scorer.
115                 continue;
116             }
117 
118             // Optionally, this package may specify a configuration activity.
119             String configurationActivityClassName = null;
120             Intent intent = new Intent(NetworkScoreManager.ACTION_CUSTOM_ENABLE);
121             intent.setPackage(receiverInfo.packageName);
122             List<ResolveInfo> configActivities = pm.queryIntentActivities(intent, 0 /* flags */);
123             if (!configActivities.isEmpty()) {
124                 ActivityInfo activityInfo = configActivities.get(0).activityInfo;
125                 if (activityInfo != null) {
126                     configurationActivityClassName = activityInfo.name;
127                 }
128             }
129 
130             // NOTE: loadLabel will attempt to load the receiver's label and fall back to the app
131             // label if none is present.
132             scorers.add(new NetworkScorerAppData(receiverInfo.packageName,
133                     receiverInfo.applicationInfo.uid, receiverInfo.loadLabel(pm),
134                     configurationActivityClassName));
135         }
136 
137         return scorers;
138     }
139 
140     /**
141      * Get the application to use for scoring networks.
142      *
143      * @return the scorer app info or null if scoring is disabled (including if no scorer was ever
144      *     selected) or if the previously-set scorer is no longer a valid scorer app (e.g. because
145      *     it was disabled or uninstalled).
146      */
getActiveScorer(Context context)147     public static NetworkScorerAppData getActiveScorer(Context context) {
148         String scorerPackage = Settings.Global.getString(context.getContentResolver(),
149                 Settings.Global.NETWORK_SCORER_APP);
150         return getScorer(context, scorerPackage);
151     }
152 
153     /**
154      * Set the specified package as the default scorer application.
155      *
156      * <p>The caller must have permission to write to {@link android.provider.Settings.Global}.
157      *
158      * @param context the context of the calling application
159      * @param packageName the packageName of the new scorer to use. If null, scoring will be
160      *     disabled. Otherwise, the scorer will only be set if it is a valid scorer application.
161      * @return true if the scorer was changed, or false if the package is not a valid scorer.
162      */
setActiveScorer(Context context, String packageName)163     public static boolean setActiveScorer(Context context, String packageName) {
164         String oldPackageName = Settings.Global.getString(context.getContentResolver(),
165                 Settings.Global.NETWORK_SCORER_APP);
166         if (TextUtils.equals(oldPackageName, packageName)) {
167             // No change.
168             return true;
169         }
170 
171         Log.i(TAG, "Changing network scorer from " + oldPackageName + " to " + packageName);
172 
173         if (packageName == null) {
174             Settings.Global.putString(context.getContentResolver(),
175                     Settings.Global.NETWORK_SCORER_APP, null);
176             return true;
177         } else {
178             // We only make the change if the new package is valid.
179             if (getScorer(context, packageName) != null) {
180                 Settings.Global.putString(context.getContentResolver(),
181                         Settings.Global.NETWORK_SCORER_APP, packageName);
182                 return true;
183             } else {
184                 Log.w(TAG, "Requested network scorer is not valid: " + packageName);
185                 return false;
186             }
187         }
188     }
189 
190     /** Determine whether the application with the given UID is the enabled scorer. */
isCallerActiveScorer(Context context, int callingUid)191     public static boolean isCallerActiveScorer(Context context, int callingUid) {
192         NetworkScorerAppData defaultApp = getActiveScorer(context);
193         if (defaultApp == null) {
194             return false;
195         }
196         if (callingUid != defaultApp.mPackageUid) {
197             return false;
198         }
199         // To be extra safe, ensure the caller holds the SCORE_NETWORKS permission. It always
200         // should, since it couldn't become the active scorer otherwise, but this can't hurt.
201         return context.checkCallingPermission(Manifest.permission.SCORE_NETWORKS) ==
202                 PackageManager.PERMISSION_GRANTED;
203     }
204 
205     /** Returns the {@link NetworkScorerAppData} for the given app, or null if it's not a scorer. */
getScorer(Context context, String packageName)206     public static NetworkScorerAppData getScorer(Context context, String packageName) {
207         if (TextUtils.isEmpty(packageName)) {
208             return null;
209         }
210         Collection<NetworkScorerAppData> applications = getAllValidScorers(context);
211         for (NetworkScorerAppData app : applications) {
212             if (packageName.equals(app.mPackageName)) {
213                 return app;
214             }
215         }
216         return null;
217     }
218 }
219