Prevent writing to FRP partition during factory reset. am: a9437bd1ca am:... (dd7837c5) · Commits · e / os / android_frameworks_base

core/java/android/service/persistentdata/PersistentDataBlockManager.java

+5 −0

Original line number	Original line	Diff line number	Diff line
	@@ -79,6 +79,9 @@ public class PersistentDataBlockManager {
	* Returns the number of bytes written or -1 on error. If the block is too big		* Returns the number of bytes written or -1 on error. If the block is too big
	* to fit on the partition, returns -MAX_BLOCK_SIZE.		* to fit on the partition, returns -MAX_BLOCK_SIZE.
	*		*
			* {@link #wipe} will block any further {@link #write} operation until reboot,
			* in which case -1 will be returned.
			*
	* @param data the data to write		* @param data the data to write
	*/		*/
	public int write(byte[] data) {		public int write(byte[] data) {
	@@ -129,6 +132,8 @@ public class PersistentDataBlockManager {
	/**		/**
	* Zeroes the previously written block in its entirety. Calling this method		* Zeroes the previously written block in its entirety. Calling this method
	* will erase all data written to the persistent data partition.		* will erase all data written to the persistent data partition.
			* It will also prevent any further {@link #write} operation until reboot,
			* in order to prevent a potential race condition. See b/30352311.
	*/		*/
	public void wipe() {		public void wipe() {
	try {		try {

services/core/java/com/android/server/PersistentDataBlockService.java

+14 −6

Original line number	Original line	Diff line number	Diff line
	@@ -53,15 +53,14 @@ import java.util.Arrays;
	* This data will live across factory resets not initiated via the Settings UI.		* 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.		* When a device is factory reset through Settings this data is wiped.
	*		*
	* Allows writing one block at a time. Namely, each time		* Allows writing one block at a time. Namely, each time {@link IPersistentDataBlockService#write}
	* {@link android.service.persistentdata.IPersistentDataBlockService}.write(byte[] data)		* is called, it will overwrite the data that was previously written on the block.
	* 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		* Clients can query the size of the currently written block via
	* {@link android.service.persistentdata.IPersistentDataBlockService}.getTotalDataSize().		* {@link IPersistentDataBlockService#getDataBlockSize}
	*		*
	* Clients can any number of bytes from the currently written block up to its total size by invoking		* Clients can read any number of bytes from the currently written block up to its total size by
	* {@link android.service.persistentdata.IPersistentDataBlockService}.read(byte[] data)		* invoking {@link IPersistentDataBlockService#read}
	*/		*/
	public class PersistentDataBlockService extends SystemService {		public class PersistentDataBlockService extends SystemService {
	private static final String TAG = PersistentDataBlockService.class.getSimpleName();		private static final String TAG = PersistentDataBlockService.class.getSimpleName();
	@@ -84,6 +83,7 @@ public class PersistentDataBlockService extends SystemService {

	private int mAllowedUid = -1;		private int mAllowedUid = -1;
	private long mBlockDeviceSize;		private long mBlockDeviceSize;
			private boolean mIsWritable = true;

	public PersistentDataBlockService(Context context) {		public PersistentDataBlockService(Context context) {
	super(context);		super(context);
	@@ -377,6 +377,11 @@ public class PersistentDataBlockService extends SystemService {
	headerAndData.put(data);		headerAndData.put(data);

	synchronized (mLock) {		synchronized (mLock) {
			if (!mIsWritable) {
			IoUtils.closeQuietly(outputStream);
			return -1;
			}

	try {		try {
	byte[] checksum = new byte[DIGEST_SIZE_BYTES];		byte[] checksum = new byte[DIGEST_SIZE_BYTES];
	outputStream.write(checksum, 0, DIGEST_SIZE_BYTES);		outputStream.write(checksum, 0, DIGEST_SIZE_BYTES);
	@@ -451,6 +456,9 @@ public class PersistentDataBlockService extends SystemService {

	if (ret < 0) {		if (ret < 0) {
	Slog.e(TAG, "failed to wipe persistent partition");		Slog.e(TAG, "failed to wipe persistent partition");
			} else {
			mIsWritable = false;
			Slog.i(TAG, "persistent partition now wiped and unwritable");
	}		}
	}		}
	}		}