Add zygote native fork loop (69d44b0b) · Commits · e / os / android_frameworks_base

core/java/android/os/ZygoteProcess.java

+1 −1

Original line number	Diff line number	Diff line
		@@ -426,7 +426,7 @@ public class ZygoteProcess {
		// avoid writing a partial response to the zygote.
		for (String arg : args) {
		// Making two indexOf calls here is faster than running a manually fused loop due
		// to the fact that indexOf is a optimized intrinsic.
		// to the fact that indexOf is an optimized intrinsic.
		if (arg.indexOf('\n') >= 0) {
		throw new ZygoteStartFailedEx("Embedded newlines not allowed");
		} else if (arg.indexOf('\r') >= 0) {

core/java/com/android/internal/os/Zygote.java

+194 −166

Original line number	Diff line number	Diff line
		@@ -18,8 +18,8 @@ package com.android.internal.os;

		import static android.system.OsConstants.O_CLOEXEC;

		import static com.android.internal.os.ZygoteConnectionConstants.MAX_ZYGOTE_ARGC;

		import android.annotation.NonNull;
		import android.annotation.Nullable;
		import android.content.pm.ApplicationInfo;
		import android.net.Credentials;
		import android.net.LocalServerSocket;
		@@ -36,17 +36,16 @@ import android.util.Log;

		import com.android.internal.net.NetworkUtilsInternal;

		import dalvik.annotation.optimization.CriticalNative;
		import dalvik.annotation.optimization.FastNative;
		import dalvik.system.ZygoteHooks;

		import libcore.io.IoUtils;

		import java.io.BufferedReader;
		import java.io.ByteArrayOutputStream;
		import java.io.DataOutputStream;
		import java.io.FileDescriptor;
		import java.io.IOException;
		import java.io.InputStreamReader;

		/** @hide */
		public final class Zygote {
		@@ -236,6 +235,8 @@ public final class Zygote {
		*/
		public static final String CHILD_ZYGOTE_UID_RANGE_END = "--uid-range-end=";

		private static final String TAG = "Zygote";

		/** Prefix prepended to socket names created by init */
		private static final String ANDROID_SOCKET_PREFIX = "ANDROID_SOCKET_";

		@@ -406,6 +407,10 @@ public final class Zygote {
		// Note that this event ends at the end of handleChildProc.
		Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "PostFork");

		if (gids != null && gids.length > 0) {
		NetworkUtilsInternal.setAllowNetworkingForProcess(containsInetGid(gids));
		}

		// Set the Java Language thread priority to the default value for new apps.
		Thread.currentThread().setPriority(Thread.NORM_PRIORITY);

		@@ -578,114 +583,163 @@ public final class Zygote {
		private static native int nativeGetUsapPoolEventFD();

		/**
		* Fork a new unspecialized app process from the zygote
		* Fork a new unspecialized app process from the zygote. Adds the Usap to the native
		* Usap table.
		*
		* @param usapPoolSocket The server socket the USAP will call accept on
		* @param sessionSocketRawFDs Anonymous session sockets that are currently open
		* @param isPriorityFork Value controlling the process priority level until accept is called
		* @return In the Zygote process this function will always return null; in unspecialized app
		* processes this function will return a Runnable object representing the new
		* application that is passed up from usapMain.
		* @param sessionSocketRawFDs Anonymous session sockets that are currently open.
		* These are closed in the child.
		* @param isPriorityFork Raise the initial process priority level because this is on the
		* critical path for application startup.
		* @return In the child process, this returns a Runnable that waits for specialization
		* info to start an app process. In the sygote/parent process this returns null.
		*/
		static Runnable forkUsap(LocalServerSocket usapPoolSocket,
		static @Nullable Runnable forkUsap(LocalServerSocket usapPoolSocket,
		int[] sessionSocketRawFDs,
		boolean isPriorityFork) {
		FileDescriptor[] pipeFDs;
		FileDescriptor readFD;
		FileDescriptor writeFD;

		try {
		pipeFDs = Os.pipe2(O_CLOEXEC);
		FileDescriptor[] pipeFDs = Os.pipe2(O_CLOEXEC);
		readFD = pipeFDs[0];
		writeFD = pipeFDs[1];
		} catch (ErrnoException errnoEx) {
		throw new IllegalStateException("Unable to create USAP pipe.", errnoEx);
		}

		int pid =
		nativeForkUsap(pipeFDs[0].getInt$(), pipeFDs[1].getInt$(),
		sessionSocketRawFDs, isPriorityFork);

		int pid = nativeForkApp(readFD.getInt$(), writeFD.getInt$(),
		sessionSocketRawFDs, /argsKnown=/ false, isPriorityFork);
		if (pid == 0) {
		IoUtils.closeQuietly(pipeFDs[0]);
		return usapMain(usapPoolSocket, pipeFDs[1]);
		IoUtils.closeQuietly(readFD);
		return childMain(null, usapPoolSocket, writeFD);
		} else if (pid == -1) {
		// Fork failed.
		return null;
		} else {
		// The read-end of the pipe will be closed by the native code.
		// See removeUsapTableEntry();
		IoUtils.closeQuietly(pipeFDs[1]);
		// readFD will be closed by the native code. See removeUsapTableEntry();
		IoUtils.closeQuietly(writeFD);
		nativeAddUsapTableEntry(pid, readFD.getInt$());
		return null;
		}
		}

		private static native int nativeForkUsap(int readPipeFD,
		private static native int nativeForkApp(int readPipeFD,
		int writePipeFD,
		int[] sessionSocketRawFDs,
		boolean argsKnown,
		boolean isPriorityFork);

		/**
		* This function is used by unspecialized app processes to wait for specialization requests from
		* the system server.
		* Add an entry for a new Usap to the table maintained in native code.
		*/
		@CriticalNative
		private static native void nativeAddUsapTableEntry(int pid, int readPipeFD);

		/**
		* Fork a new app process from the zygote. argBuffer contains a fork command that
		* request neither a child zygote, nor a wrapped process. Continue to accept connections
		* on the specified socket, use those to refill argBuffer, and continue to process
		* sufficiently simple fork requests. We presume that the only open file descriptors
		* requiring special treatment are the session socket embedded in argBuffer, and
		* zygoteSocket.
		* @param argBuffer containing initial command and the connected socket from which to
		* read more
		* @param zygoteSocket socket from which to obtain new connections when current argBuffer
		* one is disconnected
		* @param expectedUId Uid of peer for initial requests. Subsequent requests from a different
		* peer will cause us to return rather than perform the requested fork.
		* @param minUid Minimum Uid enforced for all but first fork request. The caller checks
		* the Uid policy for the initial request.
		* @param firstNiceName name of first created process. Used for error reporting only.
		* @return A Runnable in each child process, null in the parent.
		* If this returns in then argBuffer still contains a command needing to be executed.
		*/
		static @Nullable Runnable forkSimpleApps(@NonNull ZygoteCommandBuffer argBuffer,
		@NonNull FileDescriptor zygoteSocket,
		int expectedUid,
		int minUid,
		@Nullable String firstNiceName) {
		boolean in_child =
		argBuffer.forkRepeatedly(zygoteSocket, expectedUid, minUid, firstNiceName);
		if (in_child) {
		return childMain(argBuffer, /usapPoolSocket=/null, /writePipe=/null);
		} else {
		return null;
		}
		}

		/**
		* Specialize the current process into one described by argBuffer or the command read from
		* usapPoolSocket. Exactly one of those must be null. If we are given an argBuffer, we close
		* it. Used both for a specializing a USAP process, and for process creation without USAPs.
		* In both cases, we specialize the process after first returning to Java code.
		*
		* @param writePipe The write end of the reporting pipe used to communicate with the poll loop
		* of the ZygoteServer.
		* @return A runnable oject representing the new application.
		*/
		private static Runnable usapMain(LocalServerSocket usapPoolSocket,
		private static Runnable childMain(@Nullable ZygoteCommandBuffer argBuffer,
		@Nullable LocalServerSocket usapPoolSocket,
		FileDescriptor writePipe) {
		final int pid = Process.myPid();
		Process.setArgV0(Process.is64Bit() ? "usap64" : "usap32");

		LocalSocket sessionSocket = null;
		DataOutputStream usapOutputStream = null;
		Credentials peerCredentials = null;
		ZygoteArguments args = null;

		// Change the priority to max before calling accept so we can respond to new specialization
		// requests as quickly as possible. This will be reverted to the default priority in the
		// native specialization code.
		// Block SIGTERM so we won't be killed if the Zygote flushes the USAP pool.
		blockSigTerm();

		LocalSocket sessionSocket = null;
		if (argBuffer == null) {
		// Read arguments from usapPoolSocket instead.

		Process.setArgV0(Process.is64Bit() ? "usap64" : "usap32");

		// Change the priority to max before calling accept so we can respond to new
		// specialization requests as quickly as possible. This will be reverted to the
		// default priority in the native specialization code.
		boostUsapPriority();

		while (true) {
		ZygoteCommandBuffer tmpArgBuffer = null;
		try {
		sessionSocket = usapPoolSocket.accept();

		// Block SIGTERM so we won't be killed if the Zygote flushes the USAP pool.
		blockSigTerm();

		BufferedReader usapReader =
		new BufferedReader(new InputStreamReader(sessionSocket.getInputStream()));
		usapOutputStream =
		new DataOutputStream(sessionSocket.getOutputStream());

		peerCredentials = sessionSocket.getPeerCredentials();

		String[] argStrings = readArgumentList(usapReader);

		if (argStrings != null) {
		args = new ZygoteArguments(argStrings);

		Credentials peerCredentials = sessionSocket.getPeerCredentials();
		tmpArgBuffer = new ZygoteCommandBuffer(sessionSocket);
		args = ZygoteArguments.getInstance(argBuffer);
		applyUidSecurityPolicy(args, peerCredentials);
		// TODO (chriswailes): Should this only be run for debug builds?
		validateUsapCommand(args);
		break;
		} else {
		Log.e("USAP", "Truncated command received.");
		IoUtils.closeQuietly(sessionSocket);

		// Re-enable SIGTERM so the USAP can be flushed from the pool if necessary.
		unblockSigTerm();
		}
		} catch (Exception ex) {
		Log.e("USAP", ex.getMessage());
		IoUtils.closeQuietly(sessionSocket);

		}
		// Re-enable SIGTERM so the USAP can be flushed from the pool if necessary.
		unblockSigTerm();
		IoUtils.closeQuietly(sessionSocket);
		IoUtils.closeQuietly(tmpArgBuffer);
		blockSigTerm();
		}
		} else {
		try {
		args = ZygoteArguments.getInstance(argBuffer);
		} catch (Exception ex) {
		Log.e("AppStartup", ex.getMessage());
		throw new AssertionError("Failed to parse application start command", ex);
		}
		// peerCredentials were checked in parent.
		}
		if (args == null) {
		throw new AssertionError("Empty command line");
		}

		try {
		// SIGTERM is blocked on loop exit. This prevents a USAP that is specializing from
		// being killed during a pool flush.
		// SIGTERM is blocked here. This prevents a USAP that is specializing from being
		// killed during a pool flush.

		setAppProcessName(args, "USAP");

		applyUidSecurityPolicy(args, peerCredentials);
		applyDebuggerSystemProperty(args);

		int[][] rlimits = null;
		@@ -694,6 +748,7 @@ public final class Zygote {
		rlimits = args.mRLimits.toArray(INT_ARRAY_2D);
		}

		if (argBuffer == null) {
		// This must happen before the SELinux policy for this process is
		// changed when specializing.
		try {
		@@ -705,34 +760,36 @@ public final class Zygote {
		+ ioEx.getMessage());
		throw new RuntimeException(ioEx);
		} finally {
		IoUtils.closeQuietly(sessionSocket);

		try {
		// This socket is closed using Os.close due to an issue with the implementation
		// of LocalSocketImp.close(). Because the raw FD is created by init and then
		// loaded from an environment variable (as opposed to being created by the
		// LocalSocketImpl itself) the current implementation will not actually close
		// the underlying FD.
		//
		// See b/130309968 for discussion of this issue.
		Os.close(usapPoolSocket.getFileDescriptor());
		} catch (ErrnoException ex) {
		// Since the raw FD is created by init and then loaded from an environment
		// variable (as opposed to being created by the LocalSocketImpl itself),
		// the LocalSocket/LocalSocketImpl does not own the Os-level socket. See
		// the spec for LocalSocket.createConnectedLocalSocket(FileDescriptor fd).
		// Thus closing the LocalSocket does not suffice. See b/130309968 for more
		// discussion.
		FileDescriptor fd = usapPoolSocket.getFileDescriptor();
		usapPoolSocket.close();
		Os.close(fd);
		} catch (ErrnoException \| IOException ex) {
		Log.e("USAP", "Failed to close USAP pool socket");
		throw new RuntimeException(ex);
		}
		}
		}

		if (writePipe != null) {
		try {
		ByteArrayOutputStream buffer =
		new ByteArrayOutputStream(Zygote.USAP_MANAGEMENT_MESSAGE_BYTES);
		DataOutputStream outputStream = new DataOutputStream(buffer);

		// This is written as a long so that the USAP reporting pipe and USAP pool event FD
		// handlers in ZygoteServer.runSelectLoop can be unified. These two cases should
		// both send/receive 8 bytes.
		// This is written as a long so that the USAP reporting pipe and USAP pool
		// event FD handlers in ZygoteServer.runSelectLoop can be unified. These two
		// cases should both send/receive 8 bytes.
		// TODO: Needs tweaking to handle the non-Usap invoke-with case, which expects
		// a different format.
		outputStream.writeLong(pid);
		outputStream.flush();

		Os.write(writePipe, buffer.toByteArray(), 0, buffer.size());
		} catch (Exception ex) {
		Log.e("USAP",
		@@ -742,6 +799,7 @@ public final class Zygote {
		} finally {
		IoUtils.closeQuietly(writePipe);
		}
		}

		specializeAppProcess(args.mUid, args.mGid, args.mGids,
		args.mRuntimeFlags, rlimits, args.mMountExternal,
		@@ -847,13 +905,29 @@ public final class Zygote {
		return nativeRemoveUsapTableEntry(usapPID);
		}

		@CriticalNative
		private static native boolean nativeRemoveUsapTableEntry(int usapPID);

		/**
		* uid 1000 (Process.SYSTEM_UID) may specify any uid > 1000 in normal
		* Return the minimum child uid that the given peer is allowed to create.
		* uid 1000 (Process.SYSTEM_UID) may specify any uid ≥ 1000 in normal
		* operation. It may also specify any gid and setgroups() list it chooses.
		* In factory test mode, it may specify any UID.
		*
		*/
		static int minChildUid(Credentials peer) {
		if (peer.getUid() == Process.SYSTEM_UID
		&& FactoryTest.getMode() == FactoryTest.FACTORY_TEST_OFF) {
		/* In normal operation, SYSTEM_UID can only specify a restricted
		* set of UIDs. In factory test mode, SYSTEM_UID may specify any uid.
		*/
		return Process.SYSTEM_UID;
		} else {
		return 0;
		}
		}

		/*
		* Adjust uid and gid arguments, ensuring that the security policy is satisfied.
		* @param args non-null; zygote spawner arguments
		* @param peer non-null; peer credentials
		* @throws ZygoteSecurityException Indicates a security issue when applying the UID based
		@@ -862,18 +936,11 @@ public final class Zygote {
		static void applyUidSecurityPolicy(ZygoteArguments args, Credentials peer)
		throws ZygoteSecurityException {

		if (peer.getUid() == Process.SYSTEM_UID) {
		/* In normal operation, SYSTEM_UID can only specify a restricted
		* set of UIDs. In factory test mode, SYSTEM_UID may specify any uid.
		*/
		boolean uidRestricted = FactoryTest.getMode() == FactoryTest.FACTORY_TEST_OFF;

		if (uidRestricted && args.mUidSpecified && (args.mUid < Process.SYSTEM_UID)) {
		if (args.mUidSpecified && (args.mUid < minChildUid(peer))) {
		throw new ZygoteSecurityException(
		"System UID may not launch process with UID < "
		+ Process.SYSTEM_UID);
		}
		}

		// If not otherwise specified, uid and gid are inherited from peer
		if (!args.mUidSpecified) {
		@@ -957,45 +1024,6 @@ public final class Zygote {
		}
		}

		/**
		* Reads an argument list from the provided socket
		* @return Argument list or null if EOF is reached
		* @throws IOException passed straight through
		*/
		static String[] readArgumentList(BufferedReader socketReader) throws IOException {
		int argc;

		try {
		String argc_string = socketReader.readLine();

		if (argc_string == null) {
		// EOF reached.
		return null;
		}
		argc = Integer.parseInt(argc_string);

		} catch (NumberFormatException ex) {
		Log.e("Zygote", "Invalid Zygote wire format: non-int at argc");
		throw new IOException("Invalid wire format");
		}

		// See bug 1092107: large argc can be used for a DOS attack
		if (argc > MAX_ZYGOTE_ARGC) {
		throw new IOException("Max arg count exceeded");
		}

		String[] args = new String[argc];
		for (int arg_index = 0; arg_index < argc; arg_index++) {
		args[arg_index] = socketReader.readLine();
		if (args[arg_index] == null) {
		// We got an unexpected EOF.
		throw new IOException("Truncated request");
		}
		}

		return args;
		}

		/**
		* Creates a managed LocalServerSocket object using a file descriptor
		* created by an init.rc script. The init scripts that specify the

core/java/com/android/internal/os/ZygoteArguments.java

+57 −26

File changed.

Preview size limit exceeded, changes collapsed.

core/java/com/android/internal/os/ZygoteCommandBuffer.java

0 → 100644

+187 −0

File added.

Preview size limit exceeded, changes collapsed.

core/java/com/android/internal/os/ZygoteConnection.java

+181 −148

File changed.

Preview size limit exceeded, changes collapsed.