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Fixing the race condition in GenerateRkpKey

Browse Source 
This file was written on the assumption that bindService was
synchronous, which it isn't. This change adds a CountDownLatch to force
the class to wait for the binding to finish.

Bug: 190222116
Test: atest RemoteProvisionerUnitTests
Change-Id: I917a61da612f21f9a0f783bea5d24270d4e1db42
This commit is contained in:
Max Bires 2021-06-05 15:16:47 -07:00
parent ff3d2907e8
commit d05498b9d8
2 changed files with 50 additions and 20 deletions
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68
keystore/java/android/security/GenerateRkpKey.java
View File

@ -22,6 +22,10 @@ import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
/**
* GenerateKey is a helper class to handle interactions between Keystore and the RemoteProvisioner
@ -41,14 +45,25 @@ import android.os.RemoteException;
* @hide
*/
public class GenerateRkpKey {
private static final String TAG = "GenerateRkpKey";
private static final int NOTIFY_EMPTY = 0;
private static final int NOTIFY_KEY_GENERATED = 1;
private static final int TIMEOUT_MS = 1000;
private IGenerateRkpKeyService mBinder;
private Context mContext;
private CountDownLatch mCountDownLatch;
private ServiceConnection mConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName className, IBinder service) {
mBinder = IGenerateRkpKeyService.Stub.asInterface(service);
mCountDownLatch.countDown();
}
@Override public void onBindingDied(ComponentName className) {
mCountDownLatch.countDown();
}
@Override
@ -64,36 +79,51 @@ public class GenerateRkpKey {
mContext = context;
}
/**
* Fulfills the use case of (2) described in the class documentation. Blocks until the
* RemoteProvisioner application can get new attestation keys signed by the server.
*/
public void notifyEmpty(int securityLevel) throws RemoteException {
private void bindAndSendCommand(int command, int securityLevel) throws RemoteException {
Intent intent = new Intent(IGenerateRkpKeyService.class.getName());
ComponentName comp = intent.resolveSystemService(mContext.getPackageManager(), 0);
if (comp == null) {
throw new RemoteException("Could not resolve GenerateRkpKeyService.");
}
intent.setComponent(comp);
if (comp == null || !mContext.bindService(intent, mConnection, Context.BIND_AUTO_CREATE)) {
throw new RemoteException("Failed to bind to GenerateKeyService");
mCountDownLatch = new CountDownLatch(1);
if (!mContext.bindService(intent, mConnection, Context.BIND_AUTO_CREATE)) {
throw new RemoteException("Failed to bind to GenerateRkpKeyService");
}
try {
mCountDownLatch.await(TIMEOUT_MS, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
Log.e(TAG, "Interrupted: ", e);
}
if (mBinder != null) {
mBinder.generateKey(securityLevel);
switch (command) {
case NOTIFY_EMPTY:
mBinder.generateKey(securityLevel);
break;
case NOTIFY_KEY_GENERATED:
mBinder.notifyKeyGenerated(securityLevel);
break;
default:
Log.e(TAG, "Invalid case for command");
}
} else {
Log.e(TAG, "Binder object is null; failed to bind to GenerateRkpKeyService.");
}
mContext.unbindService(mConnection);
}
/**
* FUlfills the use case of (1) described in the class documentation. Non blocking call.
* Fulfills the use case of (2) described in the class documentation. Blocks until the
* RemoteProvisioner application can get new attestation keys signed by the server.
*/
public void notifyEmpty(int securityLevel) throws RemoteException {
bindAndSendCommand(NOTIFY_EMPTY, securityLevel);
}
/**
* Fulfills the use case of (1) described in the class documentation. Non blocking call.
*/
public void notifyKeyGenerated(int securityLevel) throws RemoteException {
Intent intent = new Intent(IGenerateRkpKeyService.class.getName());
ComponentName comp = intent.resolveSystemService(mContext.getPackageManager(), 0);
intent.setComponent(comp);
if (comp == null || !mContext.bindService(intent, mConnection, Context.BIND_AUTO_CREATE)) {
throw new RemoteException("Failed to bind to GenerateKeyService");
}
if (mBinder != null) {
mBinder.notifyKeyGenerated(securityLevel);
}
mContext.unbindService(mConnection);
bindAndSendCommand(NOTIFY_KEY_GENERATED, securityLevel);
}
}

2
keystore/java/android/security/keystore2/AndroidKeyStoreKeyPairGeneratorSpi.java
View File

@ -580,7 +580,7 @@ public abstract class AndroidKeyStoreKeyPairGeneratorSpi extends KeyPairGenerato
} catch (RemoteException e) {
// This is not really an error state, and necessarily does not apply to non RKP
// systems or hybrid systems where RKP is not currently turned on.
Log.d(TAG, "Couldn't connect to the RemoteProvisioner backend.");
Log.d(TAG, "Couldn't connect to the RemoteProvisioner backend.", e);
}
success = true;
return new KeyPair(publicKey, publicKey.getPrivateKey());