Prevent writing to FRP partition during factory reset. am: a9437bd1ca (133ff4d6) · Commits · e / os / android_frameworks_base

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

+5 −0

Original line number	Diff line number	Diff line
		@@ -54,6 +54,9 @@ public class PersistentDataBlockManager {
		* 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.
		*
		* {@link #wipe} will block any further {@link #write} operation until reboot,
		* in which case -1 will be returned.
		*
		* @param data the data to write
		*/
		public int write(byte[] data) {
		@@ -108,6 +111,8 @@ public class PersistentDataBlockManager {
		/**
		* Zeroes the previously written block in its entirety. Calling this method
		* 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() {
		try {

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

+14 −6

Original line number	Diff line number	Diff line
		@@ -50,15 +50,14 @@ import java.util.Arrays;
		* 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.
		* Allows writing one block at a time. Namely, each time {@link IPersistentDataBlockService#write}
		* is called, it will overwrite 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().
		* {@link IPersistentDataBlockService#getDataBlockSize}
		*
		* 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)
		* Clients can read any number of bytes from the currently written block up to its total size by
		* invoking {@link IPersistentDataBlockService#read}
		*/
		public class PersistentDataBlockService extends SystemService {
		private static final String TAG = PersistentDataBlockService.class.getSimpleName();
		@@ -78,6 +77,7 @@ public class PersistentDataBlockService extends SystemService {

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

		public PersistentDataBlockService(Context context) {
		super(context);
		@@ -349,6 +349,11 @@ public class PersistentDataBlockService extends SystemService {
		headerAndData.put(data);

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

		try {
		byte[] checksum = new byte[DIGEST_SIZE_BYTES];
		outputStream.write(checksum, 0, DIGEST_SIZE_BYTES);
		@@ -423,6 +428,9 @@ public class PersistentDataBlockService extends SystemService {

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