core/java/android/webkit/WebViewLibraryLoader.java - platform/frameworks/base.git - Git at Google

 /*
  * Copyright (C) 2017 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.webkit;

 import android.annotation.NonNull;
 import android.app.ActivityManagerInternal;
 import android.app.ActivityThread;
 import android.app.LoadedApk;
 import android.content.Context;
 import android.content.pm.PackageInfo;
 import android.os.Build;
 import android.os.Process;
 import android.os.RemoteException;
 import android.util.Log;

 import com.android.internal.annotations.VisibleForTesting;
 import com.android.server.LocalServices;

 import dalvik.system.VMRuntime;

 import java.util.Arrays;

 /**
  * @hide
  */
 @VisibleForTesting
 public class WebViewLibraryLoader {
     private static final String LOGTAG = WebViewLibraryLoader.class.getSimpleName();

     private static final String CHROMIUM_WEBVIEW_NATIVE_RELRO_32 =
             "/data/misc/shared_relro/libwebviewchromium32.relro";
     private static final String CHROMIUM_WEBVIEW_NATIVE_RELRO_64 =
             "/data/misc/shared_relro/libwebviewchromium64.relro";

     private static final boolean DEBUG = false;

     private static boolean sAddressSpaceReserved = false;

     /**
      * Private class for running the actual relro creation in an unprivileged child process.
      * RelroFileCreator is a static class (without access to the outer class) to avoid accidentally
      * using any static members from the outer class. Those members will in reality differ between
      * the child process in which RelroFileCreator operates, and the app process in which the static
      * members of this class are used.
      */
     private static class RelroFileCreator {
         // Called in an unprivileged child process to create the relro file.
         public static void main(String[] args) {
             boolean result = false;
             boolean is64Bit = VMRuntime.getRuntime().is64Bit();
             try {
                 if (args.length != 2 || args[0] == null || args[1] == null) {
                     Log.e(LOGTAG, "Invalid RelroFileCreator args: " + Arrays.toString(args));
                     return;
                 }
                 String packageName = args[0];
                 String libraryFileName = args[1];
                 Log.v(LOGTAG, "RelroFileCreator (64bit = " + is64Bit + "), package: "
                         + packageName + " library: " + libraryFileName);
                 if (!sAddressSpaceReserved) {
                     Log.e(LOGTAG, "can't create relro file; address space not reserved");
                     return;
                 }
                 LoadedApk apk = ActivityThread.currentActivityThread().getPackageInfo(
                         packageName,
                         null,
                         Context.CONTEXT_INCLUDE_CODE | Context.CONTEXT_IGNORE_SECURITY);
                 result = nativeCreateRelroFile(libraryFileName,
                                                is64Bit ? CHROMIUM_WEBVIEW_NATIVE_RELRO_64 :
                                                          CHROMIUM_WEBVIEW_NATIVE_RELRO_32,
                                                apk.getClassLoader());
                 if (result && DEBUG) Log.v(LOGTAG, "created relro file");
             } finally {
                 // We must do our best to always notify the update service, even if something fails.
                 try {
                     WebViewFactory.getUpdateServiceUnchecked().notifyRelroCreationCompleted();
                 } catch (RemoteException e) {
                     Log.e(LOGTAG, "error notifying update service", e);
                 }

                 if (!result) Log.e(LOGTAG, "failed to create relro file");

                 // Must explicitly exit or else this process will just sit around after we return.
                 System.exit(0);
             }
         }
     }

     /**
      * Create a single relro file by invoking an isolated process that to do the actual work.
      */
     static void createRelroFile(final boolean is64Bit, @NonNull String packageName,
             @NonNull String libraryFileName) {
         final String abi =
                 is64Bit ? Build.SUPPORTED_64_BIT_ABIS[0] : Build.SUPPORTED_32_BIT_ABIS[0];

         // crashHandler is invoked by the ActivityManagerService when the isolated process crashes.
         Runnable crashHandler = new Runnable() {
             @Override
             public void run() {
                 try {
                     Log.e(LOGTAG, "relro file creator for " + abi + " crashed. Proceeding without");
                     WebViewFactory.getUpdateService().notifyRelroCreationCompleted();
                 } catch (RemoteException e) {
                     Log.e(LOGTAG, "Cannot reach WebViewUpdateService. " + e.getMessage());
                 }
             }
         };

         try {
             boolean success = LocalServices.getService(ActivityManagerInternal.class)
                     .startIsolatedProcess(
                             RelroFileCreator.class.getName(),
                             new String[] { packageName, libraryFileName },
                             "WebViewLoader-" + abi, abi, Process.SHARED_RELRO_UID, crashHandler);
             if (!success) throw new Exception("Failed to start the relro file creator process");
         } catch (Throwable t) {
             // Log and discard errors as we must not crash the system server.
             Log.e(LOGTAG, "error starting relro file creator for abi " + abi, t);
             crashHandler.run();
         }
     }

     /**
      * Perform preparations needed to allow loading WebView from an application. This method should
      * be called whenever we change WebView provider.
      * @return the number of relro processes started.
      */
     static int prepareNativeLibraries(@NonNull PackageInfo webViewPackageInfo) {
         // TODO(torne): new way of calculating VM size
         // updateWebViewZygoteVmSize(nativeLib32bit, nativeLib64bit);
         String libraryFileName = WebViewFactory.getWebViewLibrary(
                 webViewPackageInfo.applicationInfo);
         if (libraryFileName == null) {
             // Can't do anything with no filename, don't spawn any processes.
             return 0;
         }
         return createRelros(webViewPackageInfo.packageName, libraryFileName);
     }

     /**
      * @return the number of relro processes started.
      */
     private static int createRelros(@NonNull String packageName, @NonNull String libraryFileName) {
         if (DEBUG) Log.v(LOGTAG, "creating relro files");
         int numRelros = 0;

         if (Build.SUPPORTED_32_BIT_ABIS.length > 0) {
             if (DEBUG) Log.v(LOGTAG, "Create 32 bit relro");
             createRelroFile(false /* is64Bit */, packageName, libraryFileName);
             numRelros++;
         }

         if (Build.SUPPORTED_64_BIT_ABIS.length > 0) {
             if (DEBUG) Log.v(LOGTAG, "Create 64 bit relro");
             createRelroFile(true /* is64Bit */, packageName, libraryFileName);
             numRelros++;
         }
         return numRelros;
     }

     /**
      * Reserve space for the native library to be loaded into.
      */
     static void reserveAddressSpaceInZygote() {
         System.loadLibrary("webviewchromium_loader");
         long addressSpaceToReserve;
         if (VMRuntime.getRuntime().is64Bit()) {
             // On 64-bit address space is really cheap and we can reserve 1GB which is plenty.
             addressSpaceToReserve = 1 * 1024 * 1024 * 1024;
         } else if (VMRuntime.getRuntime().vmInstructionSet().equals("arm")) {
             // On 32-bit the address space is fairly scarce, hence we should keep it to a realistic
             // number that permits some future growth but doesn't hog space. For ARM we use 130MB
             // which is roughly what was calculated on older OS versions. The size has been
             // growing gradually, but a few efforts have offset it back to the size close to the
             // original.
             addressSpaceToReserve = 130 * 1024 * 1024;
         } else {
             // The number below was obtained for a binary used for x86 emulators, allowing some
             // natural growth.
             addressSpaceToReserve = 190 * 1024 * 1024;
         }

         sAddressSpaceReserved = nativeReserveAddressSpace(addressSpaceToReserve);

         if (sAddressSpaceReserved) {
             if (DEBUG) {
                 Log.v(LOGTAG, "address space reserved: " + addressSpaceToReserve + " bytes");
             }
         } else {
             Log.e(LOGTAG, "reserving " + addressSpaceToReserve + " bytes of address space failed");
         }
     }

     /**
      * Load WebView's native library into the current process.
      *
      * <p class="note"><b>Note:</b> Assumes that we have waited for relro creation.
      *
      * @param clazzLoader class loader used to find the linker namespace to load the library into.
      * @param libraryFileName the filename of the library to load.
      */
     public static int loadNativeLibrary(ClassLoader clazzLoader, String libraryFileName) {
         if (!sAddressSpaceReserved) {
             Log.e(LOGTAG, "can't load with relro file; address space not reserved");
             return WebViewFactory.LIBLOAD_ADDRESS_SPACE_NOT_RESERVED;
         }

         String relroPath = VMRuntime.getRuntime().is64Bit() ? CHROMIUM_WEBVIEW_NATIVE_RELRO_64 :
                                                               CHROMIUM_WEBVIEW_NATIVE_RELRO_32;
         int result = nativeLoadWithRelroFile(libraryFileName, relroPath, clazzLoader);
         if (result != WebViewFactory.LIBLOAD_SUCCESS) {
             Log.w(LOGTAG, "failed to load with relro file, proceeding without");
         } else if (DEBUG) {
             Log.v(LOGTAG, "loaded with relro file");
         }
         return result;
     }

     static native boolean nativeReserveAddressSpace(long addressSpaceToReserve);
     static native boolean nativeCreateRelroFile(String lib, String relro, ClassLoader clazzLoader);
     static native int nativeLoadWithRelroFile(String lib, String relro, ClassLoader clazzLoader);
 }
	/*
	* Copyright (C) 2017 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.webkit;

	import android.annotation.NonNull;
	import android.app.ActivityManagerInternal;
	import android.app.ActivityThread;
	import android.app.LoadedApk;
	import android.content.Context;
	import android.content.pm.PackageInfo;
	import android.os.Build;
	import android.os.Process;
	import android.os.RemoteException;
	import android.util.Log;

	import com.android.internal.annotations.VisibleForTesting;
	import com.android.server.LocalServices;

	import dalvik.system.VMRuntime;

	import java.util.Arrays;

	/**
	* @hide
	*/
	@VisibleForTesting
	public class WebViewLibraryLoader {
	private static final String LOGTAG = WebViewLibraryLoader.class.getSimpleName();

	private static final String CHROMIUM_WEBVIEW_NATIVE_RELRO_32 =
	"/data/misc/shared_relro/libwebviewchromium32.relro";
	private static final String CHROMIUM_WEBVIEW_NATIVE_RELRO_64 =
	"/data/misc/shared_relro/libwebviewchromium64.relro";

	private static final boolean DEBUG = false;

	private static boolean sAddressSpaceReserved = false;

	/**
	* Private class for running the actual relro creation in an unprivileged child process.
	* RelroFileCreator is a static class (without access to the outer class) to avoid accidentally
	* using any static members from the outer class. Those members will in reality differ between
	* the child process in which RelroFileCreator operates, and the app process in which the static
	* members of this class are used.
	*/
	private static class RelroFileCreator {
	// Called in an unprivileged child process to create the relro file.
	public static void main(String[] args) {
	boolean result = false;
	boolean is64Bit = VMRuntime.getRuntime().is64Bit();
	try {
	if (args.length != 2 \|\| args[0] == null \|\| args[1] == null) {
	Log.e(LOGTAG, "Invalid RelroFileCreator args: " + Arrays.toString(args));
	return;
	}
	String packageName = args[0];
	String libraryFileName = args[1];
	Log.v(LOGTAG, "RelroFileCreator (64bit = " + is64Bit + "), package: "
	+ packageName + " library: " + libraryFileName);
	if (!sAddressSpaceReserved) {
	Log.e(LOGTAG, "can't create relro file; address space not reserved");
	return;
	}
	LoadedApk apk = ActivityThread.currentActivityThread().getPackageInfo(
	packageName,
	null,
	Context.CONTEXT_INCLUDE_CODE \| Context.CONTEXT_IGNORE_SECURITY);
	result = nativeCreateRelroFile(libraryFileName,
	is64Bit ? CHROMIUM_WEBVIEW_NATIVE_RELRO_64 :
	CHROMIUM_WEBVIEW_NATIVE_RELRO_32,
	apk.getClassLoader());
	if (result && DEBUG) Log.v(LOGTAG, "created relro file");
	} finally {
	// We must do our best to always notify the update service, even if something fails.
	try {
	WebViewFactory.getUpdateServiceUnchecked().notifyRelroCreationCompleted();
	} catch (RemoteException e) {
	Log.e(LOGTAG, "error notifying update service", e);
	}

	if (!result) Log.e(LOGTAG, "failed to create relro file");

	// Must explicitly exit or else this process will just sit around after we return.
	System.exit(0);
	}
	}
	}

	/**
	* Create a single relro file by invoking an isolated process that to do the actual work.
	*/
	static void createRelroFile(final boolean is64Bit, @NonNull String packageName,
	@NonNull String libraryFileName) {
	final String abi =
	is64Bit ? Build.SUPPORTED_64_BIT_ABIS[0] : Build.SUPPORTED_32_BIT_ABIS[0];

	// crashHandler is invoked by the ActivityManagerService when the isolated process crashes.
	Runnable crashHandler = new Runnable() {
	@Override
	public void run() {
	try {
	Log.e(LOGTAG, "relro file creator for " + abi + " crashed. Proceeding without");
	WebViewFactory.getUpdateService().notifyRelroCreationCompleted();
	} catch (RemoteException e) {
	Log.e(LOGTAG, "Cannot reach WebViewUpdateService. " + e.getMessage());
	}
	}
	};

	try {
	boolean success = LocalServices.getService(ActivityManagerInternal.class)
	.startIsolatedProcess(
	RelroFileCreator.class.getName(),
	new String[] { packageName, libraryFileName },
	"WebViewLoader-" + abi, abi, Process.SHARED_RELRO_UID, crashHandler);
	if (!success) throw new Exception("Failed to start the relro file creator process");
	} catch (Throwable t) {
	// Log and discard errors as we must not crash the system server.
	Log.e(LOGTAG, "error starting relro file creator for abi " + abi, t);
	crashHandler.run();
	}
	}

	/**
	* Perform preparations needed to allow loading WebView from an application. This method should
	* be called whenever we change WebView provider.
	* @return the number of relro processes started.
	*/
	static int prepareNativeLibraries(@NonNull PackageInfo webViewPackageInfo) {
	// TODO(torne): new way of calculating VM size
	// updateWebViewZygoteVmSize(nativeLib32bit, nativeLib64bit);
	String libraryFileName = WebViewFactory.getWebViewLibrary(
	webViewPackageInfo.applicationInfo);
	if (libraryFileName == null) {
	// Can't do anything with no filename, don't spawn any processes.
	return 0;
	}
	return createRelros(webViewPackageInfo.packageName, libraryFileName);
	}

	/**
	* @return the number of relro processes started.
	*/
	private static int createRelros(@NonNull String packageName, @NonNull String libraryFileName) {
	if (DEBUG) Log.v(LOGTAG, "creating relro files");
	int numRelros = 0;

	if (Build.SUPPORTED_32_BIT_ABIS.length > 0) {
	if (DEBUG) Log.v(LOGTAG, "Create 32 bit relro");
	createRelroFile(false /* is64Bit */, packageName, libraryFileName);
	numRelros++;
	}

	if (Build.SUPPORTED_64_BIT_ABIS.length > 0) {
	if (DEBUG) Log.v(LOGTAG, "Create 64 bit relro");
	createRelroFile(true /* is64Bit */, packageName, libraryFileName);
	numRelros++;
	}
	return numRelros;
	}

	/**
	* Reserve space for the native library to be loaded into.
	*/
	static void reserveAddressSpaceInZygote() {
	System.loadLibrary("webviewchromium_loader");
	long addressSpaceToReserve;
	if (VMRuntime.getRuntime().is64Bit()) {
	// On 64-bit address space is really cheap and we can reserve 1GB which is plenty.
	addressSpaceToReserve = 1 * 1024 * 1024 * 1024;
	} else if (VMRuntime.getRuntime().vmInstructionSet().equals("arm")) {
	// On 32-bit the address space is fairly scarce, hence we should keep it to a realistic
	// number that permits some future growth but doesn't hog space. For ARM we use 130MB
	// which is roughly what was calculated on older OS versions. The size has been
	// growing gradually, but a few efforts have offset it back to the size close to the
	// original.
	addressSpaceToReserve = 130 * 1024 * 1024;
	} else {
	// The number below was obtained for a binary used for x86 emulators, allowing some
	// natural growth.
	addressSpaceToReserve = 190 * 1024 * 1024;
	}

	sAddressSpaceReserved = nativeReserveAddressSpace(addressSpaceToReserve);

	if (sAddressSpaceReserved) {
	if (DEBUG) {
	Log.v(LOGTAG, "address space reserved: " + addressSpaceToReserve + " bytes");
	}
	} else {
	Log.e(LOGTAG, "reserving " + addressSpaceToReserve + " bytes of address space failed");
	}
	}

	/**
	* Load WebView's native library into the current process.
	*
	* <p class="note"><b>Note:</b> Assumes that we have waited for relro creation.
	*
	* @param clazzLoader class loader used to find the linker namespace to load the library into.
	* @param libraryFileName the filename of the library to load.
	*/
	public static int loadNativeLibrary(ClassLoader clazzLoader, String libraryFileName) {
	if (!sAddressSpaceReserved) {
	Log.e(LOGTAG, "can't load with relro file; address space not reserved");
	return WebViewFactory.LIBLOAD_ADDRESS_SPACE_NOT_RESERVED;
	}

	String relroPath = VMRuntime.getRuntime().is64Bit() ? CHROMIUM_WEBVIEW_NATIVE_RELRO_64 :
	CHROMIUM_WEBVIEW_NATIVE_RELRO_32;
	int result = nativeLoadWithRelroFile(libraryFileName, relroPath, clazzLoader);
	if (result != WebViewFactory.LIBLOAD_SUCCESS) {
	Log.w(LOGTAG, "failed to load with relro file, proceeding without");
	} else if (DEBUG) {
	Log.v(LOGTAG, "loaded with relro file");
	}
	return result;
	}

	static native boolean nativeReserveAddressSpace(long addressSpaceToReserve);
	static native boolean nativeCreateRelroFile(String lib, String relro, ClassLoader clazzLoader);
	static native int nativeLoadWithRelroFile(String lib, String relro, ClassLoader clazzLoader);
	}