No runtime exceptions during normal use of AndroidKeyStore crypto.

This changes the implementation of AndroidKeyStore-backed Cipher and
Mac to avoid throwing runtime exceptions during normal use. Runtime
exceptions will now be thrown only due to truly exceptional and
unrecoverable errors (e.g., keystore unreachable, or crypto primitive
not initialized).

This also changes the implementation of Cipher to cache any errors
encountered in Cipher.update until Cipher.doFinal which then throws
them as checked exceptions.

Bug: 20525947
Change-Id: I3c4ad57fe70abfbb817a79402f722a0208660727

1 files changed, 50 insertions, 10 deletions

diff --git a/keystore/java/android/security/KeyStoreCipherSpi.java b/keystore/java/android/security/KeyStoreCipherSpi.java
index 1f8d8ec4ff43..3b13e83520bb 100644
--- a/keystore/java/android/security/KeyStoreCipherSpi.java
+++ b/keystore/java/android/security/KeyStoreCipherSpi.java
@@ -136,6 +136,14 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
     private Long mOperationHandle;
     private KeyStoreCryptoOperationChunkedStreamer mMainDataStreamer;
 
+    /**
+     * Encountered exception which could not be immediately thrown because it was encountered inside
+     * a method that does not throw checked exception. This exception will be thrown from
+     * {@code engineDoFinal}. Once such an exception is encountered, {@code engineUpdate} and
+     * {@code engineDoFinal} start ignoring input data.
+     */
+    private Exception mCachedException;
+
     protected KeyStoreCipherSpi(
             int keymasterAlgorithm,
             int keymasterBlockMode,
@@ -158,7 +166,11 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
         try {
             init(opmode, key, random);
             initAlgorithmSpecificParameters();
-            ensureKeystoreOperationInitialized();
+            try {
+                ensureKeystoreOperationInitialized();
+            } catch (InvalidAlgorithmParameterException e) {
+                throw new InvalidKeyException(e);
+            }
             success = true;
         } finally {
             if (!success) {
@@ -236,6 +248,7 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
         mOperationToken = null;
         mOperationHandle = null;
         mMainDataStreamer = null;
+        mCachedException = null;
     }
 
     private void resetWhilePreservingInitState() {
@@ -247,12 +260,17 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
         mOperationHandle = null;
         mMainDataStreamer = null;
         mAdditionalEntropyForBegin = null;
+        mCachedException = null;
     }
 
-    private void ensureKeystoreOperationInitialized() {
+    private void ensureKeystoreOperationInitialized() throws InvalidKeyException,
+            InvalidAlgorithmParameterException {
         if (mMainDataStreamer != null) {
             return;
         }
+        if (mCachedException != null) {
+            return;
+        }
         if (mKey == null) {
             throw new IllegalStateException("Not initialized");
         }
@@ -281,11 +299,15 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
         if (opResult == null) {
             throw new KeyStoreConnectException();
         } else if (opResult.resultCode != KeyStore.NO_ERROR) {
-            throw KeyStore.getCryptoOperationException(opResult.resultCode);
+            switch (opResult.resultCode) {
+                case KeymasterDefs.KM_ERROR_INVALID_NONCE:
+                    throw new InvalidAlgorithmParameterException("Invalid IV");
+            }
+            throw KeyStore.getInvalidKeyException(opResult.resultCode);
         }
 
         if (opResult.token == null) {
-            throw new CryptoOperationException("Keystore returned null operation token");
+            throw new IllegalStateException("Keystore returned null operation token");
         }
         mOperationToken = opResult.token;
         mOperationHandle = opResult.operationHandle;
@@ -299,7 +321,15 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
 
     @Override
     protected byte[] engineUpdate(byte[] input, int inputOffset, int inputLen) {
-        ensureKeystoreOperationInitialized();
+        if (mCachedException != null) {
+            return null;
+        }
+        try {
+            ensureKeystoreOperationInitialized();
+        } catch (InvalidKeyException | InvalidAlgorithmParameterException e) {
+            mCachedException = e;
+            return null;
+        }
 
         if (inputLen == 0) {
             return null;
@@ -309,7 +339,8 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
         try {
             output = mMainDataStreamer.update(input, inputOffset, inputLen);
         } catch (KeyStoreException e) {
-            throw KeyStore.getCryptoOperationException(e);
+            mCachedException = e;
+            return null;
         }
 
         if (output.length == 0) {
@@ -338,7 +369,16 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
     @Override
     protected byte[] engineDoFinal(byte[] input, int inputOffset, int inputLen)
             throws IllegalBlockSizeException, BadPaddingException {
-        ensureKeystoreOperationInitialized();
+        if (mCachedException != null) {
+            throw (IllegalBlockSizeException)
+                    new IllegalBlockSizeException().initCause(mCachedException);
+        }
+
+        try {
+            ensureKeystoreOperationInitialized();
+        } catch (InvalidKeyException | InvalidAlgorithmParameterException e) {
+            throw (IllegalBlockSizeException) new IllegalBlockSizeException().initCause(e);
+        }
 
         byte[] output;
         try {
@@ -352,7 +392,7 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
                 case KeymasterDefs.KM_ERROR_VERIFICATION_FAILED:
                     throw new AEADBadTagException();
                 default:
-                    throw KeyStore.getCryptoOperationException(e);
+                    throw (IllegalBlockSizeException) new IllegalBlockSizeException().initCause(e);
             }
         }
 
@@ -613,11 +653,11 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
             if (mIv == null) {
                 mIv = returnedIv;
             } else if ((returnedIv != null) && (!Arrays.equals(returnedIv, mIv))) {
-                throw new CryptoOperationException("IV in use differs from provided IV");
+                throw new IllegalStateException("IV in use differs from provided IV");
             }
         } else {
             if (returnedIv != null) {
-                throw new CryptoOperationException(
+                throw new IllegalStateException(
                         "IV in use despite IV not being used by this transformation");
             }
         }