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Initial support for application Zygote.

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When an application has requested isolated services to be spawned
from an app zygote, we need to spawn the app zygote itself, and then
ask it to fork an isolated service.

The application zygote currently only creates the class loader, and
doesn't do much else. We keep track of the isolated services that
use the app zygote, and when the last isolated service goes away,
we stop the app zygote itself (after a timeout).

The app zygote itself runs with the app's UID and under the app
seccomp filter. That last one is too restricted, so this currently
only works with SELinux disabled.

Future CLs will add an application callback for preloading.

Test: start multiple isolated services with useAppZygote="true",
      verify app_zygote starts, services start as a child of
      app_zygote. Stopping all services stops app_zygote as well.

Bug: 111434506

Change-Id: I10ee1d4bd148c9298974d434fbc5e5eccbec16cb
This commit is contained in:
Martijn Coenen
2018-11-05 11:45:26 +01:00
parent caa6519f68
commit 7e6fa6727c
11 changed files with 496 additions and 50 deletions
Download Patch File Download Diff File Expand all files Collapse all files

116
core/java/android/os/AppZygote.java Normal file
View File

@@ -0,0 +1,116 @@
/*
* Copyright (C) 2018 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.os;
import android.content.pm.ApplicationInfo;
import android.util.Log;
import com.android.internal.annotations.GuardedBy;
/**
* AppZygote is responsible for interfacing with an application-specific zygote.
*
* Application zygotes can pre-load app-specific code and data, and this interface can
* be used to spawn isolated services from such an application zygote.
*
* Note that we'll have only one instance of this per application / uid combination.
*
* @hide
*/
public class AppZygote {
private static final String LOG_TAG = "AppZygote";
private final Object mLock = new Object();
/**
* Instance that maintains the socket connection to the zygote. This is {@code null} if the
* zygote is not running or is not connected.
*/
@GuardedBy("mLock")
private ChildZygoteProcess mZygote;
private final ApplicationInfo mAppInfo;
public AppZygote(ApplicationInfo appInfo) {
mAppInfo = appInfo;
}
/**
* Returns the zygote process associated with this app zygote.
* Creates the process if it's not already running.
*/
public ChildZygoteProcess getProcess() {
synchronized (mLock) {
if (mZygote != null) return mZygote;
connectToZygoteIfNeededLocked();
return mZygote;
}
}
/**
* Stops the Zygote and kills the zygote process.
*/
public void stopZygote() {
synchronized (mLock) {
stopZygoteLocked();
}
}
public ApplicationInfo getAppInfo() {
return mAppInfo;
}
@GuardedBy("mLock")
private void stopZygoteLocked() {
if (mZygote != null) {
// Close the connection and kill the zygote process. This will not cause
// child processes to be killed by itself.
mZygote.close();
Process.killProcess(mZygote.getPid());
mZygote = null;
}
}
@GuardedBy("mLock")
private void connectToZygoteIfNeededLocked() {
String abi = mAppInfo.primaryCpuAbi != null ? mAppInfo.primaryCpuAbi :
Build.SUPPORTED_ABIS[0];
try {
mZygote = Process.zygoteProcess.startChildZygote(
"com.android.internal.os.AppZygoteInit",
mAppInfo.processName + "_zygote",
mAppInfo.uid,
mAppInfo.uid,
null, // gids
0, // runtimeFlags
"app_zygote", // seInfo
abi, // abi
abi, // acceptedAbiList
null); // instructionSet
ZygoteProcess.waitForConnectionToZygote(mZygote.getPrimarySocketAddress());
// preload application code in the zygote
Log.i(LOG_TAG, "Starting application preload.");
mZygote.preloadApp(mAppInfo, abi);
Log.i(LOG_TAG, "Application preload done.");
} catch (Exception e) {
Log.e(LOG_TAG, "Error connecting to app zygote", e);
stopZygoteLocked();
}
}
}

50
core/java/android/os/ZygoteProcess.java
View File

@@ -18,6 +18,7 @@ package android.os;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.content.pm.ApplicationInfo;
import android.net.LocalSocket;
import android.net.LocalSocketAddress;
import android.util.Log;
@@ -34,6 +35,7 @@ import java.io.OutputStreamWriter;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Base64;
import java.util.Collections;
import java.util.List;
import java.util.UUID;
@@ -672,6 +674,36 @@ public class ZygoteProcess {
throw new ZygoteStartFailedEx("Unsupported zygote ABI: " + abi);
}
/**
* Instructs the zygote to pre-load the application code for the given Application.
* Only the app zygote supports this function.
* TODO preloadPackageForAbi() can probably be removed and the callers an use this instead.
*/
public boolean preloadApp(ApplicationInfo appInfo, String abi) throws ZygoteStartFailedEx,
IOException {
synchronized (mLock) {
ZygoteState state = openZygoteSocketIfNeeded(abi);
state.writer.write("2");
state.writer.newLine();
state.writer.write("--preload-app");
state.writer.newLine();
// Zygote args needs to be strings, so in order to pass ApplicationInfo,
// write it to a Parcel, and base64 the raw Parcel bytes to the other side.
Parcel parcel = Parcel.obtain();
appInfo.writeToParcel(parcel, 0 /* flags */);
String encodedParcelData = Base64.getEncoder().encodeToString(parcel.marshall());
parcel.recycle();
state.writer.write(encodedParcelData);
state.writer.newLine();
state.writer.flush();
return (state.inputStream.readInt() == 0);
}
}
/**
* Instructs the zygote to pre-load the classes and native libraries at the given paths
* for the specified abi. Not all zygotes support this function.
@@ -763,6 +795,20 @@ public class ZygoteProcess {
* secondary zygotes that inherit data from the zygote that this object
* communicates with. This returns a new ZygoteProcess representing a connection
* to the newly created zygote. Throws an exception if the zygote cannot be started.
*
* @param processClass The class to use as the child zygote's main entry
* point.
* @param niceName A more readable name to use for the process.
* @param uid The user-id under which the child zygote will run.
* @param gid The group-id under which the child zygote will run.
* @param gids Additional group-ids associated with the child zygote process.
* @param runtimeFlags Additional flags.
* @param seInfo null-ok SELinux information for the child zygote process.
* @param abi non-null the ABI of the child zygote
* @param acceptedAbiList ABIs this child zygote will accept connections for; this
* may be different from <code>abi</code> in case the children
* spawned from this Zygote only communicate using ABI-safe methods.
* @param instructionSet null-ok the instruction set to use.
*/
public ChildZygoteProcess startChildZygote(final String processClass,
final String niceName,
@@ -770,12 +816,14 @@ public class ZygoteProcess {
int runtimeFlags,
String seInfo,
String abi,
String acceptedAbiList,
String instructionSet) {
// Create an unguessable address in the global abstract namespace.
final LocalSocketAddress serverAddress = new LocalSocketAddress(
processClass + "/" + UUID.randomUUID().toString());
final String[] extraArgs = {Zygote.CHILD_ZYGOTE_SOCKET_NAME_ARG + serverAddress.getName()};
final String[] extraArgs = {Zygote.CHILD_ZYGOTE_SOCKET_NAME_ARG + serverAddress.getName(),
Zygote.CHILD_ZYGOTE_ABI_LIST_ARG + acceptedAbiList};
Process.ProcessStartResult result;
try {

1
core/java/android/webkit/WebViewZygote.java
View File

@@ -159,6 +159,7 @@ public class WebViewZygote {
0, // runtimeFlags
"webview_zygote", // seInfo
sPackage.applicationInfo.primaryCpuAbi, // abi
TextUtils.join(",", Build.SUPPORTED_ABIS),
null); // instructionSet
// All the work below is usually done by LoadedApk, but the zygote can't talk to