| /* |
| * Copyright (C) 2014 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 com.android.server; |
| |
| import android.Manifest; |
| import android.app.ActivityManager; |
| import android.content.Context; |
| import android.content.pm.PackageManager; |
| import android.os.Binder; |
| import android.os.IBinder; |
| import android.os.RemoteException; |
| import android.os.SystemProperties; |
| import android.os.UserHandle; |
| import android.os.UserManager; |
| import android.provider.Settings; |
| import android.service.persistentdata.IPersistentDataBlockService; |
| import android.service.persistentdata.PersistentDataBlockManager; |
| import android.util.Slog; |
| |
| import com.android.internal.R; |
| |
| import libcore.io.IoUtils; |
| |
| import java.io.DataInputStream; |
| import java.io.DataOutputStream; |
| import java.io.File; |
| import java.io.FileInputStream; |
| import java.io.FileNotFoundException; |
| import java.io.FileOutputStream; |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| import java.nio.channels.FileChannel; |
| import java.security.MessageDigest; |
| import java.security.NoSuchAlgorithmException; |
| import java.util.Arrays; |
| |
| /** |
| * Service for reading and writing blocks to a persistent partition. |
| * This data will live across factory resets not initiated via the Settings UI. |
| * When a device is factory reset through Settings this data is wiped. |
| * |
| * Allows writing one block at a time. Namely, each time |
| * {@link android.service.persistentdata.IPersistentDataBlockService}.write(byte[] data) |
| * is called, it will overwite the data that was previously written on the block. |
| * |
| * Clients can query the size of the currently written block via |
| * {@link android.service.persistentdata.IPersistentDataBlockService}.getTotalDataSize(). |
| * |
| * Clients can any number of bytes from the currently written block up to its total size by invoking |
| * {@link android.service.persistentdata.IPersistentDataBlockService}.read(byte[] data) |
| */ |
| public class PersistentDataBlockService extends SystemService { |
| private static final String TAG = PersistentDataBlockService.class.getSimpleName(); |
| |
| private static final String PERSISTENT_DATA_BLOCK_PROP = "ro.frp.pst"; |
| private static final int HEADER_SIZE = 8; |
| // Magic number to mark block device as adhering to the format consumed by this service |
| private static final int PARTITION_TYPE_MARKER = 0x19901873; |
| // Limit to 100k as blocks larger than this might cause strain on Binder. |
| private static final int MAX_DATA_BLOCK_SIZE = 1024 * 100; |
| public static final int DIGEST_SIZE_BYTES = 32; |
| private static final String OEM_UNLOCK_PROP = "sys.oem_unlock_allowed"; |
| private static final String FLASH_LOCK_PROP = "ro.boot.flash.locked"; |
| private static final String FLASH_LOCK_LOCKED = "1"; |
| private static final String FLASH_LOCK_UNLOCKED = "0"; |
| |
| private final Context mContext; |
| private final String mDataBlockFile; |
| private final Object mLock = new Object(); |
| |
| private int mAllowedUid = -1; |
| private long mBlockDeviceSize; |
| |
| public PersistentDataBlockService(Context context) { |
| super(context); |
| mContext = context; |
| mDataBlockFile = SystemProperties.get(PERSISTENT_DATA_BLOCK_PROP); |
| mBlockDeviceSize = -1; // Load lazily |
| mAllowedUid = getAllowedUid(UserHandle.USER_SYSTEM); |
| } |
| |
| private int getAllowedUid(int userHandle) { |
| String allowedPackage = mContext.getResources() |
| .getString(R.string.config_persistentDataPackageName); |
| PackageManager pm = mContext.getPackageManager(); |
| int allowedUid = -1; |
| try { |
| allowedUid = pm.getPackageUidAsUser(allowedPackage, |
| PackageManager.MATCH_SYSTEM_ONLY, userHandle); |
| } catch (PackageManager.NameNotFoundException e) { |
| // not expected |
| Slog.e(TAG, "not able to find package " + allowedPackage, e); |
| } |
| return allowedUid; |
| } |
| |
| @Override |
| public void onStart() { |
| enforceChecksumValidity(); |
| formatIfOemUnlockEnabled(); |
| publishBinderService(Context.PERSISTENT_DATA_BLOCK_SERVICE, mService); |
| } |
| |
| private void formatIfOemUnlockEnabled() { |
| boolean enabled = doGetOemUnlockEnabled(); |
| if (enabled) { |
| synchronized (mLock) { |
| formatPartitionLocked(true); |
| } |
| } |
| |
| SystemProperties.set(OEM_UNLOCK_PROP, enabled ? "1" : "0"); |
| } |
| |
| private void enforceOemUnlockPermission() { |
| mContext.enforceCallingOrSelfPermission( |
| Manifest.permission.OEM_UNLOCK_STATE, |
| "Can't access OEM unlock state"); |
| } |
| |
| private void enforceUid(int callingUid) { |
| if (callingUid != mAllowedUid) { |
| throw new SecurityException("uid " + callingUid + " not allowed to access PST"); |
| } |
| } |
| |
| private void enforceIsAdmin() { |
| final int userId = UserHandle.getCallingUserId(); |
| final boolean isAdmin = UserManager.get(mContext).isUserAdmin(userId); |
| if (!isAdmin) { |
| throw new SecurityException( |
| "Only the Admin user is allowed to change OEM unlock state"); |
| } |
| } |
| |
| private void enforceFactoryResetAllowed() { |
| final boolean isOemUnlockRestricted = UserManager.get(mContext) |
| .hasUserRestriction(UserManager.DISALLOW_FACTORY_RESET); |
| if (isOemUnlockRestricted) { |
| throw new SecurityException("OEM unlock is disallowed by DISALLOW_FACTORY_RESET"); |
| } |
| } |
| |
| private int getTotalDataSizeLocked(DataInputStream inputStream) throws IOException { |
| // skip over checksum |
| inputStream.skipBytes(DIGEST_SIZE_BYTES); |
| |
| int totalDataSize; |
| int blockId = inputStream.readInt(); |
| if (blockId == PARTITION_TYPE_MARKER) { |
| totalDataSize = inputStream.readInt(); |
| } else { |
| totalDataSize = 0; |
| } |
| return totalDataSize; |
| } |
| |
| private long getBlockDeviceSize() { |
| synchronized (mLock) { |
| if (mBlockDeviceSize == -1) { |
| mBlockDeviceSize = nativeGetBlockDeviceSize(mDataBlockFile); |
| } |
| } |
| |
| return mBlockDeviceSize; |
| } |
| |
| private boolean enforceChecksumValidity() { |
| byte[] storedDigest = new byte[DIGEST_SIZE_BYTES]; |
| |
| synchronized (mLock) { |
| byte[] digest = computeDigestLocked(storedDigest); |
| if (digest == null || !Arrays.equals(storedDigest, digest)) { |
| Slog.i(TAG, "Formatting FRP partition..."); |
| formatPartitionLocked(false); |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| private boolean computeAndWriteDigestLocked() { |
| byte[] digest = computeDigestLocked(null); |
| if (digest != null) { |
| DataOutputStream outputStream; |
| try { |
| outputStream = new DataOutputStream( |
| new FileOutputStream(new File(mDataBlockFile))); |
| } catch (FileNotFoundException e) { |
| Slog.e(TAG, "partition not available?", e); |
| return false; |
| } |
| |
| try { |
| outputStream.write(digest, 0, DIGEST_SIZE_BYTES); |
| outputStream.flush(); |
| } catch (IOException e) { |
| Slog.e(TAG, "failed to write block checksum", e); |
| return false; |
| } finally { |
| IoUtils.closeQuietly(outputStream); |
| } |
| return true; |
| } else { |
| return false; |
| } |
| } |
| |
| private byte[] computeDigestLocked(byte[] storedDigest) { |
| DataInputStream inputStream; |
| try { |
| inputStream = new DataInputStream(new FileInputStream(new File(mDataBlockFile))); |
| } catch (FileNotFoundException e) { |
| Slog.e(TAG, "partition not available?", e); |
| return null; |
| } |
| |
| MessageDigest md; |
| try { |
| md = MessageDigest.getInstance("SHA-256"); |
| } catch (NoSuchAlgorithmException e) { |
| // won't ever happen -- every implementation is required to support SHA-256 |
| Slog.e(TAG, "SHA-256 not supported?", e); |
| IoUtils.closeQuietly(inputStream); |
| return null; |
| } |
| |
| try { |
| if (storedDigest != null && storedDigest.length == DIGEST_SIZE_BYTES) { |
| inputStream.read(storedDigest); |
| } else { |
| inputStream.skipBytes(DIGEST_SIZE_BYTES); |
| } |
| |
| int read; |
| byte[] data = new byte[1024]; |
| md.update(data, 0, DIGEST_SIZE_BYTES); // include 0 checksum in digest |
| while ((read = inputStream.read(data)) != -1) { |
| md.update(data, 0, read); |
| } |
| } catch (IOException e) { |
| Slog.e(TAG, "failed to read partition", e); |
| return null; |
| } finally { |
| IoUtils.closeQuietly(inputStream); |
| } |
| |
| return md.digest(); |
| } |
| |
| private void formatPartitionLocked(boolean setOemUnlockEnabled) { |
| DataOutputStream outputStream; |
| try { |
| outputStream = new DataOutputStream(new FileOutputStream(new File(mDataBlockFile))); |
| } catch (FileNotFoundException e) { |
| Slog.e(TAG, "partition not available?", e); |
| return; |
| } |
| |
| byte[] data = new byte[DIGEST_SIZE_BYTES]; |
| try { |
| outputStream.write(data, 0, DIGEST_SIZE_BYTES); |
| outputStream.writeInt(PARTITION_TYPE_MARKER); |
| outputStream.writeInt(0); // data size |
| outputStream.flush(); |
| } catch (IOException e) { |
| Slog.e(TAG, "failed to format block", e); |
| return; |
| } finally { |
| IoUtils.closeQuietly(outputStream); |
| } |
| |
| doSetOemUnlockEnabledLocked(setOemUnlockEnabled); |
| computeAndWriteDigestLocked(); |
| } |
| |
| private void doSetOemUnlockEnabledLocked(boolean enabled) { |
| FileOutputStream outputStream; |
| try { |
| outputStream = new FileOutputStream(new File(mDataBlockFile)); |
| } catch (FileNotFoundException e) { |
| Slog.e(TAG, "partition not available", e); |
| return; |
| } |
| |
| try { |
| FileChannel channel = outputStream.getChannel(); |
| |
| channel.position(getBlockDeviceSize() - 1); |
| |
| ByteBuffer data = ByteBuffer.allocate(1); |
| data.put(enabled ? (byte) 1 : (byte) 0); |
| data.flip(); |
| channel.write(data); |
| outputStream.flush(); |
| } catch (IOException e) { |
| Slog.e(TAG, "unable to access persistent partition", e); |
| return; |
| } finally { |
| SystemProperties.set(OEM_UNLOCK_PROP, enabled ? "1" : "0"); |
| IoUtils.closeQuietly(outputStream); |
| } |
| } |
| |
| private boolean doGetOemUnlockEnabled() { |
| DataInputStream inputStream; |
| try { |
| inputStream = new DataInputStream(new FileInputStream(new File(mDataBlockFile))); |
| } catch (FileNotFoundException e) { |
| Slog.e(TAG, "partition not available"); |
| return false; |
| } |
| |
| try { |
| synchronized (mLock) { |
| inputStream.skip(getBlockDeviceSize() - 1); |
| return inputStream.readByte() != 0; |
| } |
| } catch (IOException e) { |
| Slog.e(TAG, "unable to access persistent partition", e); |
| return false; |
| } finally { |
| IoUtils.closeQuietly(inputStream); |
| } |
| } |
| |
| private native long nativeGetBlockDeviceSize(String path); |
| private native int nativeWipe(String path); |
| |
| private final IBinder mService = new IPersistentDataBlockService.Stub() { |
| @Override |
| public int write(byte[] data) throws RemoteException { |
| enforceUid(Binder.getCallingUid()); |
| |
| // Need to ensure we don't write over the last byte |
| long maxBlockSize = getBlockDeviceSize() - HEADER_SIZE - 1; |
| if (data.length > maxBlockSize) { |
| // partition is ~500k so shouldn't be a problem to downcast |
| return (int) -maxBlockSize; |
| } |
| |
| DataOutputStream outputStream; |
| try { |
| outputStream = new DataOutputStream(new FileOutputStream(new File(mDataBlockFile))); |
| } catch (FileNotFoundException e) { |
| Slog.e(TAG, "partition not available?", e); |
| return -1; |
| } |
| |
| ByteBuffer headerAndData = ByteBuffer.allocate(data.length + HEADER_SIZE); |
| headerAndData.putInt(PARTITION_TYPE_MARKER); |
| headerAndData.putInt(data.length); |
| headerAndData.put(data); |
| |
| synchronized (mLock) { |
| try { |
| byte[] checksum = new byte[DIGEST_SIZE_BYTES]; |
| outputStream.write(checksum, 0, DIGEST_SIZE_BYTES); |
| outputStream.write(headerAndData.array()); |
| outputStream.flush(); |
| } catch (IOException e) { |
| Slog.e(TAG, "failed writing to the persistent data block", e); |
| return -1; |
| } finally { |
| IoUtils.closeQuietly(outputStream); |
| } |
| |
| if (computeAndWriteDigestLocked()) { |
| return data.length; |
| } else { |
| return -1; |
| } |
| } |
| } |
| |
| @Override |
| public byte[] read() { |
| enforceUid(Binder.getCallingUid()); |
| if (!enforceChecksumValidity()) { |
| return new byte[0]; |
| } |
| |
| DataInputStream inputStream; |
| try { |
| inputStream = new DataInputStream(new FileInputStream(new File(mDataBlockFile))); |
| } catch (FileNotFoundException e) { |
| Slog.e(TAG, "partition not available?", e); |
| return null; |
| } |
| |
| try { |
| synchronized (mLock) { |
| int totalDataSize = getTotalDataSizeLocked(inputStream); |
| |
| if (totalDataSize == 0) { |
| return new byte[0]; |
| } |
| |
| byte[] data = new byte[totalDataSize]; |
| int read = inputStream.read(data, 0, totalDataSize); |
| if (read < totalDataSize) { |
| // something went wrong, not returning potentially corrupt data |
| Slog.e(TAG, "failed to read entire data block. bytes read: " + |
| read + "/" + totalDataSize); |
| return null; |
| } |
| return data; |
| } |
| } catch (IOException e) { |
| Slog.e(TAG, "failed to read data", e); |
| return null; |
| } finally { |
| try { |
| inputStream.close(); |
| } catch (IOException e) { |
| Slog.e(TAG, "failed to close OutputStream"); |
| } |
| } |
| } |
| |
| @Override |
| public void wipe() { |
| enforceOemUnlockPermission(); |
| |
| synchronized (mLock) { |
| int ret = nativeWipe(mDataBlockFile); |
| |
| if (ret < 0) { |
| Slog.e(TAG, "failed to wipe persistent partition"); |
| } |
| } |
| } |
| |
| @Override |
| public void setOemUnlockEnabled(boolean enabled) throws SecurityException { |
| // do not allow monkey to flip the flag |
| if (ActivityManager.isUserAMonkey()) { |
| return; |
| } |
| |
| enforceOemUnlockPermission(); |
| enforceIsAdmin(); |
| |
| // Do not allow oem unlock modification if it has been disallowed. |
| if (Settings.Global.getInt(getContext().getContentResolver(), |
| Settings.Global.OEM_UNLOCK_DISALLOWED, 0) == 1) { |
| throw new SecurityException("OEM unlock has been disallowed."); |
| } |
| if (enabled) { |
| enforceFactoryResetAllowed(); |
| } |
| synchronized (mLock) { |
| doSetOemUnlockEnabledLocked(enabled); |
| computeAndWriteDigestLocked(); |
| } |
| } |
| |
| @Override |
| public boolean getOemUnlockEnabled() { |
| enforceOemUnlockPermission(); |
| return doGetOemUnlockEnabled(); |
| } |
| |
| @Override |
| public int getFlashLockState() { |
| enforceOemUnlockPermission(); |
| String locked = SystemProperties.get(FLASH_LOCK_PROP); |
| switch (locked) { |
| case FLASH_LOCK_LOCKED: |
| return PersistentDataBlockManager.FLASH_LOCK_LOCKED; |
| case FLASH_LOCK_UNLOCKED: |
| return PersistentDataBlockManager.FLASH_LOCK_UNLOCKED; |
| default: |
| return PersistentDataBlockManager.FLASH_LOCK_UNKNOWN; |
| } |
| } |
| |
| @Override |
| public int getDataBlockSize() { |
| enforcePersistentDataBlockAccess(); |
| |
| DataInputStream inputStream; |
| try { |
| inputStream = new DataInputStream(new FileInputStream(new File(mDataBlockFile))); |
| } catch (FileNotFoundException e) { |
| Slog.e(TAG, "partition not available"); |
| return 0; |
| } |
| |
| try { |
| synchronized (mLock) { |
| return getTotalDataSizeLocked(inputStream); |
| } |
| } catch (IOException e) { |
| Slog.e(TAG, "error reading data block size"); |
| return 0; |
| } finally { |
| IoUtils.closeQuietly(inputStream); |
| } |
| } |
| |
| private void enforcePersistentDataBlockAccess() { |
| if (mContext.checkCallingPermission(Manifest.permission.ACCESS_PDB_STATE) |
| != PackageManager.PERMISSION_GRANTED) { |
| enforceUid(Binder.getCallingUid()); |
| } |
| } |
| |
| @Override |
| public long getMaximumDataBlockSize() { |
| long actualSize = getBlockDeviceSize() - HEADER_SIZE - 1; |
| return actualSize <= MAX_DATA_BLOCK_SIZE ? actualSize : MAX_DATA_BLOCK_SIZE; |
| } |
| }; |
| } |