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am 29db396e: am 6722598e: Merge "Add a checksum to FRP partition" into lmp-mr1-dev

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* commit '29db396ea91651f2f17e21629f782ce4c19e0f33':
  Add a checksum to FRP partition
This commit is contained in:
Andres Morales
2014-11-19 18:21:19 +00:00
committed by Android Git Automerger
parent b380d7eeee 29db396ea9
commit 39843bfbed
1 changed files with 169 additions and 46 deletions
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215
services/core/java/com/android/server/PersistentDataBlockService.java
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@@ -41,6 +41,9 @@ 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.
@@ -63,22 +66,16 @@ public class PersistentDataBlockService extends SystemService {
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 = 0x1990;
private static final int PARTITION_TYPE_MARKER = 0x19901873;
// Limit to 100k as blocks larger than this might cause strain on Binder.
// TODO(anmorales): Consider splitting up too-large blocks in PersistentDataBlockManager
private static final int MAX_DATA_BLOCK_SIZE = 1024 * 100;
public static final int DIGEST_SIZE_BYTES = 32;
private final Context mContext;
private final String mDataBlockFile;
private final Object mLock = new Object();
private int mAllowedUid = -1;
/*
* Separate lock for OEM unlock related operations as they can happen in parallel with regular
* block operations.
*/
private final Object mOemLock = new Object();
private long mBlockDeviceSize;
public PersistentDataBlockService(Context context) {
@@ -89,7 +86,6 @@ public class PersistentDataBlockService extends SystemService {
mAllowedUid = getAllowedUid(UserHandle.USER_OWNER);
}
private int getAllowedUid(int userHandle) {
String allowedPackage = mContext.getResources()
.getString(R.string.config_persistentDataPackageName);
@@ -106,6 +102,7 @@ public class PersistentDataBlockService extends SystemService {
@Override
public void onStart() {
enforceChecksumValidity();
publishBinderService(Context.PERSISTENT_DATA_BLOCK_SERVICE, mService);
}
@@ -128,6 +125,9 @@ public class PersistentDataBlockService extends SystemService {
}
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) {
@@ -148,6 +148,143 @@ public class PersistentDataBlockService extends SystemService {
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();
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() {
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(false);
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 {
IoUtils.closeQuietly(outputStream);
}
}
private native long nativeGetBlockDeviceSize(String path);
private native int nativeWipe(String path);
@@ -176,19 +313,23 @@ public class PersistentDataBlockService extends SystemService {
headerAndData.putInt(data.length);
headerAndData.put(data);
try {
synchronized (mLock) {
outputStream.write(headerAndData.array());
return data.length;
}
} catch (IOException e) {
Slog.e(TAG, "failed writing to the persistent data block", e);
return -1;
} finally {
synchronized (mLock) {
try {
outputStream.close();
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 closing output stream", 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;
}
}
}
@@ -196,6 +337,9 @@ public class PersistentDataBlockService extends SystemService {
@Override
public byte[] read() {
enforceUid(Binder.getCallingUid());
if (!enforceChecksumValidity()) {
return new byte[0];
}
DataInputStream inputStream;
try {
@@ -256,30 +400,10 @@ public class PersistentDataBlockService extends SystemService {
}
enforceOemUnlockPermission();
enforceIsOwner();
FileOutputStream outputStream;
try {
outputStream = new FileOutputStream(new File(mDataBlockFile));
} catch (FileNotFoundException e) {
Slog.e(TAG, "parition 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();
synchronized (mOemLock) {
channel.write(data);
}
} catch (IOException e) {
Slog.e(TAG, "unable to access persistent partition", e);
} finally {
IoUtils.closeQuietly(outputStream);
synchronized (mLock) {
doSetOemUnlockEnabledLocked(enabled);
computeAndWriteDigestLocked();
}
}
@@ -295,8 +419,8 @@ public class PersistentDataBlockService extends SystemService {
}
try {
inputStream.skip(getBlockDeviceSize() - 1);
synchronized (mOemLock) {
synchronized (mLock) {
inputStream.skip(getBlockDeviceSize() - 1);
return inputStream.readByte() != 0;
}
} catch (IOException e) {
@@ -336,6 +460,5 @@ public class PersistentDataBlockService extends SystemService {
long actualSize = getBlockDeviceSize() - HEADER_SIZE - 1;
return actualSize <= MAX_DATA_BLOCK_SIZE ? actualSize : MAX_DATA_BLOCK_SIZE;
}
};
}