1 /*
2  * Copyright (C) 2019 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 package com.android.compatibility.common.util.mainline;
17 
18 import android.content.pm.PackageInfo;
19 import android.content.pm.PackageManager;
20 import android.util.Log;
21 
22 import java.security.MessageDigest;
23 import java.util.EnumSet;
24 import java.util.HashSet;
25 import java.util.Set;
26 
27 /**
28  * Detects mainline modules.
29  */
30 public class ModuleDetector {
31     private static final String LOG_TAG = "MainlineModuleDetector";
32 
33     private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
34 
35     /**
36      * Return true if a module is play managed.
37      *
38      * Example of skipping a test based on mainline modules:
39      * <pre>
40      *  @Test
41      *  public void testPocCVE_1234_5678() throws Exception {
42      *      if(!ModuleDetector.moduleIsPlayManaged(
43      *          getInstrumentation().getContext().getPackageManager(),
44      *          MainlineModule.MEDIA_SOFTWARE_CODEC)) {
45      *          doStagefrightTest(R.raw.cve_2018_5882);
46      *      }
47      *  }
48      * </pre>
49      */
moduleIsPlayManaged(PackageManager pm, MainlineModule module)50     public static boolean moduleIsPlayManaged(PackageManager pm, MainlineModule module)
51             throws Exception {
52         return getPlayManagedModules(pm).contains(module);
53     }
54 
55 
56     /**
57      * Return all play managed mainline modules.
58      */
getPlayManagedModules(PackageManager pm)59     public static Set<MainlineModule> getPlayManagedModules(PackageManager pm) throws Exception {
60         Set<MainlineModule> playManagedModules = new HashSet<>();
61 
62         Set<String> packages = new HashSet<>();
63         for (PackageInfo info : pm.getInstalledPackages(0)) {
64             packages.add(info.packageName);
65         }
66         for (PackageInfo info : pm.getInstalledPackages(PackageManager.MATCH_APEX)) {
67             packages.add(info.packageName);
68         }
69 
70         for (MainlineModule module : EnumSet.allOf(MainlineModule.class)) {
71             if (module.isPlayUpdated && packages.contains(module.packageName)
72                     && module.certSHA256.equals(getSignatureDigest(pm, module))) {
73                 playManagedModules.add(module);
74             }
75         }
76         return playManagedModules;
77     }
78 
getSignatureDigest(PackageManager pm, MainlineModule module)79     private static String getSignatureDigest(PackageManager pm, MainlineModule module)
80             throws Exception {
81         int flag = PackageManager.GET_SIGNING_CERTIFICATES;
82         if (module.moduleType == ModuleType.APEX) {
83             flag |= PackageManager.MATCH_APEX;
84         }
85 
86         PackageInfo packageInfo = pm.getPackageInfo(module.packageName, flag);
87         MessageDigest messageDigest = MessageDigest.getInstance("SHA256");
88         messageDigest.update(packageInfo.signingInfo.getApkContentsSigners()[0].toByteArray());
89 
90         final byte[] digest = messageDigest.digest();
91         final int digestLength = digest.length;
92         final int charCount = 3 * digestLength - 1;
93 
94         final char[] chars = new char[charCount];
95         for (int i = 0; i < digestLength; i++) {
96             final int byteHex = digest[i] & 0xFF;
97             chars[i * 3] = HEX_ARRAY[byteHex >>> 4];
98             chars[i * 3 + 1] = HEX_ARRAY[byteHex & 0x0F];
99             if (i < digestLength - 1) {
100                 chars[i * 3 + 2] = ':';
101             }
102         }
103 
104         String ret = new String(chars);
105         Log.d(LOG_TAG, "Module: " + module.packageName + " has signature: " + ret);
106         return ret;
107     }
108 }
109