1 /*
2  * Copyright (C) 2018 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.os;
18 
19 import android.content.pm.ApplicationInfo;
20 import android.content.pm.ProcessInfo;
21 import android.util.Log;
22 
23 import com.android.internal.annotations.GuardedBy;
24 import com.android.internal.os.Zygote;
25 
26 import dalvik.system.VMRuntime;
27 
28 /**
29  * AppZygote is responsible for interfacing with an application-specific zygote.
30  *
31  * Application zygotes can pre-load app-specific code and data, and this interface can
32  * be used to spawn isolated services from such an application zygote.
33  *
34  * Note that we'll have only one instance of this per application / uid combination.
35  *
36  * @hide
37  */
38 public class AppZygote {
39     private static final String LOG_TAG = "AppZygote";
40 
41     // UID of the Zygote itself
42     private final int mZygoteUid;
43 
44     // First UID/GID of the range the AppZygote can setuid()/setgid() to
45     private final int mZygoteUidGidMin;
46 
47     // Last UID/GID of the range the AppZygote can setuid()/setgid() to
48     private final int mZygoteUidGidMax;
49 
50     private final Object mLock = new Object();
51 
52     /**
53      * Instance that maintains the socket connection to the zygote. This is {@code null} if the
54      * zygote is not running or is not connected.
55      */
56     @GuardedBy("mLock")
57     private ChildZygoteProcess mZygote;
58 
59     private final ApplicationInfo mAppInfo;
60     private final ProcessInfo mProcessInfo;
61 
AppZygote(ApplicationInfo appInfo, ProcessInfo processInfo, int zygoteUid, int uidGidMin, int uidGidMax)62     public AppZygote(ApplicationInfo appInfo, ProcessInfo processInfo, int zygoteUid, int uidGidMin,
63             int uidGidMax) {
64         mAppInfo = appInfo;
65         mProcessInfo = processInfo;
66         mZygoteUid = zygoteUid;
67         mZygoteUidGidMin = uidGidMin;
68         mZygoteUidGidMax = uidGidMax;
69     }
70 
71     /**
72      * Returns the zygote process associated with this app zygote.
73      * Creates the process if it's not already running.
74      */
getProcess()75     public ChildZygoteProcess getProcess() {
76         synchronized (mLock) {
77             if (mZygote != null) return mZygote;
78 
79             connectToZygoteIfNeededLocked();
80             return mZygote;
81         }
82     }
83 
84     /**
85      * Stops the Zygote and kills the zygote process.
86      */
stopZygote()87     public void stopZygote() {
88         synchronized (mLock) {
89             stopZygoteLocked();
90         }
91     }
92 
getAppInfo()93     public ApplicationInfo getAppInfo() {
94         return mAppInfo;
95     }
96 
97     @GuardedBy("mLock")
stopZygoteLocked()98     private void stopZygoteLocked() {
99         if (mZygote != null) {
100             mZygote.close();
101             // use killProcessGroup() here, so we kill all untracked children as well.
102             Process.killProcessGroup(mZygoteUid, mZygote.getPid());
103             mZygote = null;
104         }
105     }
106 
107     @GuardedBy("mLock")
connectToZygoteIfNeededLocked()108     private void connectToZygoteIfNeededLocked() {
109         String abi = mAppInfo.primaryCpuAbi != null ? mAppInfo.primaryCpuAbi :
110                 Build.SUPPORTED_ABIS[0];
111         try {
112             int runtimeFlags = Zygote.getMemorySafetyRuntimeFlagsForSecondaryZygote(
113                     mAppInfo, mProcessInfo);
114             mZygote = Process.ZYGOTE_PROCESS.startChildZygote(
115                     "com.android.internal.os.AppZygoteInit",
116                     mAppInfo.processName + "_zygote",
117                     mZygoteUid,
118                     mZygoteUid,
119                     null,  // gids
120                     runtimeFlags,
121                     "app_zygote",  // seInfo
122                     abi,  // abi
123                     abi, // acceptedAbiList
124                     VMRuntime.getInstructionSet(abi), // instructionSet
125                     mZygoteUidGidMin,
126                     mZygoteUidGidMax);
127 
128             ZygoteProcess.waitForConnectionToZygote(mZygote.getPrimarySocketAddress());
129             // preload application code in the zygote
130             Log.i(LOG_TAG, "Starting application preload.");
131             mZygote.preloadApp(mAppInfo, abi);
132             Log.i(LOG_TAG, "Application preload done.");
133         } catch (Exception e) {
134             Log.e(LOG_TAG, "Error connecting to app zygote", e);
135             stopZygoteLocked();
136         }
137     }
138 }
139