android.os.ZygoteProcess Maven / Gradle / Ivy
Show all versions of android-all Show documentation
/*
* Copyright (C) 2016 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.net.LocalSocket;
import android.net.LocalSocketAddress;
import android.util.Log;
import android.util.Slog;
import com.android.internal.annotations.GuardedBy;
import com.android.internal.os.Zygote;
import com.android.internal.util.Preconditions;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.UUID;
/*package*/ class ZygoteStartFailedEx extends Exception {
ZygoteStartFailedEx(String s) {
super(s);
}
ZygoteStartFailedEx(Throwable cause) {
super(cause);
}
ZygoteStartFailedEx(String s, Throwable cause) {
super(s, cause);
}
}
/**
* Maintains communication state with the zygote processes. This class is responsible
* for the sockets opened to the zygotes and for starting processes on behalf of the
* {@link android.os.Process} class.
*
* {@hide}
*/
public class ZygoteProcess {
private static final String LOG_TAG = "ZygoteProcess";
/**
* The name of the socket used to communicate with the primary zygote.
*/
private final LocalSocketAddress mSocket;
/**
* The name of the secondary (alternate ABI) zygote socket.
*/
private final LocalSocketAddress mSecondarySocket;
public ZygoteProcess(String primarySocket, String secondarySocket) {
this(new LocalSocketAddress(primarySocket, LocalSocketAddress.Namespace.RESERVED),
new LocalSocketAddress(secondarySocket, LocalSocketAddress.Namespace.RESERVED));
}
public ZygoteProcess(LocalSocketAddress primarySocket, LocalSocketAddress secondarySocket) {
mSocket = primarySocket;
mSecondarySocket = secondarySocket;
}
public LocalSocketAddress getPrimarySocketAddress() {
return mSocket;
}
/**
* State for communicating with the zygote process.
*/
public static class ZygoteState {
final LocalSocket socket;
final DataInputStream inputStream;
final BufferedWriter writer;
final List abiList;
boolean mClosed;
private ZygoteState(LocalSocket socket, DataInputStream inputStream,
BufferedWriter writer, List abiList) {
this.socket = socket;
this.inputStream = inputStream;
this.writer = writer;
this.abiList = abiList;
}
public static ZygoteState connect(LocalSocketAddress address) throws IOException {
DataInputStream zygoteInputStream = null;
BufferedWriter zygoteWriter = null;
final LocalSocket zygoteSocket = new LocalSocket();
try {
zygoteSocket.connect(address);
zygoteInputStream = new DataInputStream(zygoteSocket.getInputStream());
zygoteWriter = new BufferedWriter(new OutputStreamWriter(
zygoteSocket.getOutputStream()), 256);
} catch (IOException ex) {
try {
zygoteSocket.close();
} catch (IOException ignore) {
}
throw ex;
}
String abiListString = getAbiList(zygoteWriter, zygoteInputStream);
Log.i("Zygote", "Process: zygote socket " + address.getNamespace() + "/"
+ address.getName() + " opened, supported ABIS: " + abiListString);
return new ZygoteState(zygoteSocket, zygoteInputStream, zygoteWriter,
Arrays.asList(abiListString.split(",")));
}
boolean matches(String abi) {
return abiList.contains(abi);
}
public void close() {
try {
socket.close();
} catch (IOException ex) {
Log.e(LOG_TAG,"I/O exception on routine close", ex);
}
mClosed = true;
}
boolean isClosed() {
return mClosed;
}
}
/**
* Lock object to protect access to the two ZygoteStates below. This lock must be
* acquired while communicating over the ZygoteState's socket, to prevent
* interleaved access.
*/
private final Object mLock = new Object();
/**
* List of exemptions to the API blacklist. These are prefix matches on the runtime format
* symbol signature. Any matching symbol is treated by the runtime as being on the light grey
* list.
*/
private List mApiBlacklistExemptions = Collections.emptyList();
/**
* Proportion of hidden API accesses that should be logged to the event log; 0 - 0x10000.
*/
private int mHiddenApiAccessLogSampleRate;
/**
* The state of the connection to the primary zygote.
*/
private ZygoteState primaryZygoteState;
/**
* The state of the connection to the secondary zygote.
*/
private ZygoteState secondaryZygoteState;
/**
* Start a new process.
*
* If processes are enabled, a new process is created and the
* static main() function of a processClass is executed there.
* The process will continue running after this function returns.
*
*
If processes are not enabled, a new thread in the caller's
* process is created and main() of processclass called there.
*
*
The niceName parameter, if not an empty string, is a custom name to
* give to the process instead of using processClass. This allows you to
* make easily identifyable processes even if you are using the same base
* processClass to start them.
*
* When invokeWith is not null, the process will be started as a fresh app
* and not a zygote fork. Note that this is only allowed for uid 0 or when
* runtimeFlags contains DEBUG_ENABLE_DEBUGGER.
*
* @param processClass The class to use as the process's main entry
* point.
* @param niceName A more readable name to use for the process.
* @param uid The user-id under which the process will run.
* @param gid The group-id under which the process will run.
* @param gids Additional group-ids associated with the process.
* @param runtimeFlags Additional flags.
* @param targetSdkVersion The target SDK version for the app.
* @param seInfo null-ok SELinux information for the new process.
* @param abi non-null the ABI this app should be started with.
* @param instructionSet null-ok the instruction set to use.
* @param appDataDir null-ok the data directory of the app.
* @param invokeWith null-ok the command to invoke with.
* @param zygoteArgs Additional arguments to supply to the zygote process.
*
* @return An object that describes the result of the attempt to start the process.
* @throws RuntimeException on fatal start failure
*/
public final Process.ProcessStartResult start(final String processClass,
final String niceName,
int uid, int gid, int[] gids,
int runtimeFlags, int mountExternal,
int targetSdkVersion,
String seInfo,
String abi,
String instructionSet,
String appDataDir,
String invokeWith,
String[] zygoteArgs) {
try {
return startViaZygote(processClass, niceName, uid, gid, gids,
runtimeFlags, mountExternal, targetSdkVersion, seInfo,
abi, instructionSet, appDataDir, invokeWith, false /* startChildZygote */,
zygoteArgs);
} catch (ZygoteStartFailedEx ex) {
Log.e(LOG_TAG,
"Starting VM process through Zygote failed");
throw new RuntimeException(
"Starting VM process through Zygote failed", ex);
}
}
/** retry interval for opening a zygote socket */
static final int ZYGOTE_RETRY_MILLIS = 500;
/**
* Queries the zygote for the list of ABIS it supports.
*
* @throws ZygoteStartFailedEx if the query failed.
*/
@GuardedBy("mLock")
private static String getAbiList(BufferedWriter writer, DataInputStream inputStream)
throws IOException {
// Each query starts with the argument count (1 in this case)
writer.write("1");
// ... followed by a new-line.
writer.newLine();
// ... followed by our only argument.
writer.write("--query-abi-list");
writer.newLine();
writer.flush();
// The response is a length prefixed stream of ASCII bytes.
int numBytes = inputStream.readInt();
byte[] bytes = new byte[numBytes];
inputStream.readFully(bytes);
return new String(bytes, StandardCharsets.US_ASCII);
}
/**
* Sends an argument list to the zygote process, which starts a new child
* and returns the child's pid. Please note: the present implementation
* replaces newlines in the argument list with spaces.
*
* @throws ZygoteStartFailedEx if process start failed for any reason
*/
@GuardedBy("mLock")
private static Process.ProcessStartResult zygoteSendArgsAndGetResult(
ZygoteState zygoteState, ArrayList args)
throws ZygoteStartFailedEx {
try {
// Throw early if any of the arguments are malformed. This means we can
// avoid writing a partial response to the zygote.
int sz = args.size();
for (int i = 0; i < sz; i++) {
if (args.get(i).indexOf('\n') >= 0) {
throw new ZygoteStartFailedEx("embedded newlines not allowed");
}
}
/**
* See com.android.internal.os.SystemZygoteInit.readArgumentList()
* Presently the wire format to the zygote process is:
* a) a count of arguments (argc, in essence)
* b) a number of newline-separated argument strings equal to count
*
* After the zygote process reads these it will write the pid of
* the child or -1 on failure, followed by boolean to
* indicate whether a wrapper process was used.
*/
final BufferedWriter writer = zygoteState.writer;
final DataInputStream inputStream = zygoteState.inputStream;
writer.write(Integer.toString(args.size()));
writer.newLine();
for (int i = 0; i < sz; i++) {
String arg = args.get(i);
writer.write(arg);
writer.newLine();
}
writer.flush();
// Should there be a timeout on this?
Process.ProcessStartResult result = new Process.ProcessStartResult();
// Always read the entire result from the input stream to avoid leaving
// bytes in the stream for future process starts to accidentally stumble
// upon.
result.pid = inputStream.readInt();
result.usingWrapper = inputStream.readBoolean();
if (result.pid < 0) {
throw new ZygoteStartFailedEx("fork() failed");
}
return result;
} catch (IOException ex) {
zygoteState.close();
throw new ZygoteStartFailedEx(ex);
}
}
/**
* Starts a new process via the zygote mechanism.
*
* @param processClass Class name whose static main() to run
* @param niceName 'nice' process name to appear in ps
* @param uid a POSIX uid that the new process should setuid() to
* @param gid a POSIX gid that the new process shuold setgid() to
* @param gids null-ok; a list of supplementary group IDs that the
* new process should setgroup() to.
* @param runtimeFlags Additional flags for the runtime.
* @param targetSdkVersion The target SDK version for the app.
* @param seInfo null-ok SELinux information for the new process.
* @param abi the ABI the process should use.
* @param instructionSet null-ok the instruction set to use.
* @param appDataDir null-ok the data directory of the app.
* @param startChildZygote Start a sub-zygote. This creates a new zygote process
* that has its state cloned from this zygote process.
* @param extraArgs Additional arguments to supply to the zygote process.
* @return An object that describes the result of the attempt to start the process.
* @throws ZygoteStartFailedEx if process start failed for any reason
*/
private Process.ProcessStartResult startViaZygote(final String processClass,
final String niceName,
final int uid, final int gid,
final int[] gids,
int runtimeFlags, int mountExternal,
int targetSdkVersion,
String seInfo,
String abi,
String instructionSet,
String appDataDir,
String invokeWith,
boolean startChildZygote,
String[] extraArgs)
throws ZygoteStartFailedEx {
ArrayList argsForZygote = new ArrayList();
// --runtime-args, --setuid=, --setgid=,
// and --setgroups= must go first
argsForZygote.add("--runtime-args");
argsForZygote.add("--setuid=" + uid);
argsForZygote.add("--setgid=" + gid);
argsForZygote.add("--runtime-flags=" + runtimeFlags);
if (mountExternal == Zygote.MOUNT_EXTERNAL_DEFAULT) {
argsForZygote.add("--mount-external-default");
} else if (mountExternal == Zygote.MOUNT_EXTERNAL_READ) {
argsForZygote.add("--mount-external-read");
} else if (mountExternal == Zygote.MOUNT_EXTERNAL_WRITE) {
argsForZygote.add("--mount-external-write");
}
argsForZygote.add("--target-sdk-version=" + targetSdkVersion);
// --setgroups is a comma-separated list
if (gids != null && gids.length > 0) {
StringBuilder sb = new StringBuilder();
sb.append("--setgroups=");
int sz = gids.length;
for (int i = 0; i < sz; i++) {
if (i != 0) {
sb.append(',');
}
sb.append(gids[i]);
}
argsForZygote.add(sb.toString());
}
if (niceName != null) {
argsForZygote.add("--nice-name=" + niceName);
}
if (seInfo != null) {
argsForZygote.add("--seinfo=" + seInfo);
}
if (instructionSet != null) {
argsForZygote.add("--instruction-set=" + instructionSet);
}
if (appDataDir != null) {
argsForZygote.add("--app-data-dir=" + appDataDir);
}
if (invokeWith != null) {
argsForZygote.add("--invoke-with");
argsForZygote.add(invokeWith);
}
if (startChildZygote) {
argsForZygote.add("--start-child-zygote");
}
argsForZygote.add(processClass);
if (extraArgs != null) {
for (String arg : extraArgs) {
argsForZygote.add(arg);
}
}
synchronized(mLock) {
return zygoteSendArgsAndGetResult(openZygoteSocketIfNeeded(abi), argsForZygote);
}
}
/**
* Closes the connections to the zygote, if they exist.
*/
public void close() {
if (primaryZygoteState != null) {
primaryZygoteState.close();
}
if (secondaryZygoteState != null) {
secondaryZygoteState.close();
}
}
/**
* Tries to establish a connection to the zygote that handles a given {@code abi}. Might block
* and retry if the zygote is unresponsive. This method is a no-op if a connection is
* already open.
*/
public void establishZygoteConnectionForAbi(String abi) {
try {
synchronized(mLock) {
openZygoteSocketIfNeeded(abi);
}
} catch (ZygoteStartFailedEx ex) {
throw new RuntimeException("Unable to connect to zygote for abi: " + abi, ex);
}
}
/**
* Push hidden API blacklisting exemptions into the zygote process(es).
*
* The list of exemptions will take affect for all new processes forked from the zygote after
* this call.
*
* @param exemptions List of hidden API exemption prefixes. Any matching members are treated as
* whitelisted/public APIs (i.e. allowed, no logging of usage).
*/
public boolean setApiBlacklistExemptions(List exemptions) {
synchronized (mLock) {
mApiBlacklistExemptions = exemptions;
boolean ok = maybeSetApiBlacklistExemptions(primaryZygoteState, true);
if (ok) {
ok = maybeSetApiBlacklistExemptions(secondaryZygoteState, true);
}
return ok;
}
}
/**
* Set the precentage of detected hidden API accesses that are logged to the event log.
*
* This rate will take affect for all new processes forked from the zygote after this call.
*
* @param rate An integer between 0 and 0x10000 inclusive. 0 means no event logging.
*/
public void setHiddenApiAccessLogSampleRate(int rate) {
synchronized (mLock) {
mHiddenApiAccessLogSampleRate = rate;
maybeSetHiddenApiAccessLogSampleRate(primaryZygoteState);
maybeSetHiddenApiAccessLogSampleRate(secondaryZygoteState);
}
}
@GuardedBy("mLock")
private boolean maybeSetApiBlacklistExemptions(ZygoteState state, boolean sendIfEmpty) {
if (state == null || state.isClosed()) {
Slog.e(LOG_TAG, "Can't set API blacklist exemptions: no zygote connection");
return false;
}
if (!sendIfEmpty && mApiBlacklistExemptions.isEmpty()) {
return true;
}
try {
state.writer.write(Integer.toString(mApiBlacklistExemptions.size() + 1));
state.writer.newLine();
state.writer.write("--set-api-blacklist-exemptions");
state.writer.newLine();
for (int i = 0; i < mApiBlacklistExemptions.size(); ++i) {
state.writer.write(mApiBlacklistExemptions.get(i));
state.writer.newLine();
}
state.writer.flush();
int status = state.inputStream.readInt();
if (status != 0) {
Slog.e(LOG_TAG, "Failed to set API blacklist exemptions; status " + status);
}
return true;
} catch (IOException ioe) {
Slog.e(LOG_TAG, "Failed to set API blacklist exemptions", ioe);
mApiBlacklistExemptions = Collections.emptyList();
return false;
}
}
private void maybeSetHiddenApiAccessLogSampleRate(ZygoteState state) {
if (state == null || state.isClosed()) {
return;
}
if (mHiddenApiAccessLogSampleRate == -1) {
return;
}
try {
state.writer.write(Integer.toString(1));
state.writer.newLine();
state.writer.write("--hidden-api-log-sampling-rate="
+ Integer.toString(mHiddenApiAccessLogSampleRate));
state.writer.newLine();
state.writer.flush();
int status = state.inputStream.readInt();
if (status != 0) {
Slog.e(LOG_TAG, "Failed to set hidden API log sampling rate; status " + status);
}
} catch (IOException ioe) {
Slog.e(LOG_TAG, "Failed to set hidden API log sampling rate", ioe);
}
}
/**
* Tries to open socket to Zygote process if not already open. If
* already open, does nothing. May block and retry. Requires that mLock be held.
*/
@GuardedBy("mLock")
private ZygoteState openZygoteSocketIfNeeded(String abi) throws ZygoteStartFailedEx {
Preconditions.checkState(Thread.holdsLock(mLock), "ZygoteProcess lock not held");
if (primaryZygoteState == null || primaryZygoteState.isClosed()) {
try {
primaryZygoteState = ZygoteState.connect(mSocket);
} catch (IOException ioe) {
throw new ZygoteStartFailedEx("Error connecting to primary zygote", ioe);
}
maybeSetApiBlacklistExemptions(primaryZygoteState, false);
maybeSetHiddenApiAccessLogSampleRate(primaryZygoteState);
}
if (primaryZygoteState.matches(abi)) {
return primaryZygoteState;
}
// The primary zygote didn't match. Try the secondary.
if (secondaryZygoteState == null || secondaryZygoteState.isClosed()) {
try {
secondaryZygoteState = ZygoteState.connect(mSecondarySocket);
} catch (IOException ioe) {
throw new ZygoteStartFailedEx("Error connecting to secondary zygote", ioe);
}
maybeSetApiBlacklistExemptions(secondaryZygoteState, false);
maybeSetHiddenApiAccessLogSampleRate(secondaryZygoteState);
}
if (secondaryZygoteState.matches(abi)) {
return secondaryZygoteState;
}
throw new ZygoteStartFailedEx("Unsupported zygote ABI: " + abi);
}
/**
* 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.
*/
public boolean preloadPackageForAbi(String packagePath, String libsPath, String libFileName,
String cacheKey, String abi) throws ZygoteStartFailedEx,
IOException {
synchronized(mLock) {
ZygoteState state = openZygoteSocketIfNeeded(abi);
state.writer.write("5");
state.writer.newLine();
state.writer.write("--preload-package");
state.writer.newLine();
state.writer.write(packagePath);
state.writer.newLine();
state.writer.write(libsPath);
state.writer.newLine();
state.writer.write(libFileName);
state.writer.newLine();
state.writer.write(cacheKey);
state.writer.newLine();
state.writer.flush();
return (state.inputStream.readInt() == 0);
}
}
/**
* Instructs the zygote to preload the default set of classes and resources. Returns
* {@code true} if a preload was performed as a result of this call, and {@code false}
* otherwise. The latter usually means that the zygote eagerly preloaded at startup
* or due to a previous call to {@code preloadDefault}. Note that this call is synchronous.
*/
public boolean preloadDefault(String abi) throws ZygoteStartFailedEx, IOException {
synchronized (mLock) {
ZygoteState state = openZygoteSocketIfNeeded(abi);
// Each query starts with the argument count (1 in this case)
state.writer.write("1");
state.writer.newLine();
state.writer.write("--preload-default");
state.writer.newLine();
state.writer.flush();
return (state.inputStream.readInt() == 0);
}
}
/**
* Try connecting to the Zygote over and over again until we hit a time-out.
* @param socketName The name of the socket to connect to.
*/
public static void waitForConnectionToZygote(String socketName) {
final LocalSocketAddress address =
new LocalSocketAddress(socketName, LocalSocketAddress.Namespace.RESERVED);
waitForConnectionToZygote(address);
}
/**
* Try connecting to the Zygote over and over again until we hit a time-out.
* @param address The name of the socket to connect to.
*/
public static void waitForConnectionToZygote(LocalSocketAddress address) {
for (int n = 20; n >= 0; n--) {
try {
final ZygoteState zs = ZygoteState.connect(address);
zs.close();
return;
} catch (IOException ioe) {
Log.w(LOG_TAG,
"Got error connecting to zygote, retrying. msg= " + ioe.getMessage());
}
try {
Thread.sleep(1000);
} catch (InterruptedException ie) {
}
}
Slog.wtf(LOG_TAG, "Failed to connect to Zygote through socket " + address.getName());
}
/**
* Starts a new zygote process as a child of this zygote. This is used to create
* 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.
*/
public ChildZygoteProcess startChildZygote(final String processClass,
final String niceName,
int uid, int gid, int[] gids,
int runtimeFlags,
String seInfo,
String abi,
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()};
Process.ProcessStartResult result;
try {
result = startViaZygote(processClass, niceName, uid, gid,
gids, runtimeFlags, 0 /* mountExternal */, 0 /* targetSdkVersion */, seInfo,
abi, instructionSet, null /* appDataDir */, null /* invokeWith */,
true /* startChildZygote */, extraArgs);
} catch (ZygoteStartFailedEx ex) {
throw new RuntimeException("Starting child-zygote through Zygote failed", ex);
}
return new ChildZygoteProcess(serverAddress, result.pid);
}
}