1 files changed, 139 insertions, 0 deletions
diff --git a/packages/BackupEncryption/src/com/android/server/backup/encryption/tasks/EncryptedKvRestoreTask.java b/packages/BackupEncryption/src/com/android/server/backup/encryption/tasks/EncryptedKvRestoreTask.java
new file mode 100644
index 000000000000..12b44590ebe6
--- /dev/null
+++ b/packages/BackupEncryption/src/com/android/server/backup/encryption/tasks/EncryptedKvRestoreTask.java
@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.backup.encryption.tasks;
+
+import static com.android.internal.util.Preconditions.checkArgument;
+
+import android.app.backup.BackupDataOutput;
+import android.content.Context;
+import android.os.ParcelFileDescriptor;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.server.backup.encryption.FullRestoreDownloader;
+import com.android.server.backup.encryption.chunking.ChunkHasher;
+import com.android.server.backup.encryption.keys.RecoverableKeyStoreSecondaryKeyManager;
+import com.android.server.backup.encryption.keys.RestoreKeyFetcher;
+import com.android.server.backup.encryption.kv.DecryptedChunkKvOutput;
+import com.android.server.backup.encryption.protos.nano.KeyValuePairProto;
+import com.android.server.backup.encryption.protos.nano.WrappedKeyProto;
+
+import java.io.File;
+import java.io.IOException;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.KeyException;
+import java.security.NoSuchAlgorithmException;
+
+import javax.crypto.BadPaddingException;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.SecretKey;
+import javax.crypto.ShortBufferException;
+
+/**
+ * Performs a key value restore by downloading the backup set, decrypting it and writing it to the
+ * file provided by backup manager.
+ */
+public class EncryptedKvRestoreTask {
+    private static final String ENCRYPTED_FILE_NAME = "encrypted_kv";
+
+    private final File mTemporaryFolder;
+    private final ChunkHasher mChunkHasher;
+    private final FullRestoreToFileTask mFullRestoreToFileTask;
+    private final BackupFileDecryptorTask mBackupFileDecryptorTask;
+
+    /** Constructs new instances of the task. */
+    public static class EncryptedKvRestoreTaskFactory {
+        /**
+         * Constructs a new instance.
+         *
+         * <p>Fetches the appropriate secondary key and uses this to unwrap the tertiary key. Stores
+         * temporary files in {@link Context#getFilesDir()}.
+         */
+        public EncryptedKvRestoreTask newInstance(
+                Context context,
+                RecoverableKeyStoreSecondaryKeyManager
+                                .RecoverableKeyStoreSecondaryKeyManagerProvider
+                        recoverableSecondaryKeyManagerProvider,
+                FullRestoreDownloader fullRestoreDownloader,
+                String secondaryKeyAlias,
+                WrappedKeyProto.WrappedKey wrappedTertiaryKey)
+                throws EncryptedRestoreException, NoSuchAlgorithmException, NoSuchPaddingException,
+                        KeyException, InvalidAlgorithmParameterException {
+            SecretKey tertiaryKey =
+                    RestoreKeyFetcher.unwrapTertiaryKey(
+                            recoverableSecondaryKeyManagerProvider,
+                            secondaryKeyAlias,
+                            wrappedTertiaryKey);
+
+            return new EncryptedKvRestoreTask(
+                    context.getFilesDir(),
+                    new ChunkHasher(tertiaryKey),
+                    new FullRestoreToFileTask(fullRestoreDownloader),
+                    new BackupFileDecryptorTask(tertiaryKey));
+        }
+    }
+
+    @VisibleForTesting
+    EncryptedKvRestoreTask(
+            File temporaryFolder,
+            ChunkHasher chunkHasher,
+            FullRestoreToFileTask fullRestoreToFileTask,
+            BackupFileDecryptorTask backupFileDecryptorTask) {
+        checkArgument(
+                temporaryFolder.isDirectory(), "Temporary folder must be an existing directory");
+
+        mTemporaryFolder = temporaryFolder;
+        mChunkHasher = chunkHasher;
+        mFullRestoreToFileTask = fullRestoreToFileTask;
+        mBackupFileDecryptorTask = backupFileDecryptorTask;
+    }
+
+    /**
+     * Runs the restore, writing the pairs in lexicographical order to the given file descriptor.
+     *
+     * <p>This will block for the duration of the restore.
+     *
+     * @throws EncryptedRestoreException if there is a problem decrypting or verifying the backup
+     */
+    public void getRestoreData(ParcelFileDescriptor output)
+            throws IOException, EncryptedRestoreException, BadPaddingException,
+                    InvalidAlgorithmParameterException, NoSuchAlgorithmException,
+                    IllegalBlockSizeException, ShortBufferException, InvalidKeyException {
+        File encryptedFile = new File(mTemporaryFolder, ENCRYPTED_FILE_NAME);
+        try {
+            downloadDecryptAndWriteBackup(encryptedFile, output);
+        } finally {
+            encryptedFile.delete();
+        }
+    }
+
+    private void downloadDecryptAndWriteBackup(File encryptedFile, ParcelFileDescriptor output)
+            throws EncryptedRestoreException, IOException, BadPaddingException, InvalidKeyException,
+                    NoSuchAlgorithmException, IllegalBlockSizeException, ShortBufferException,
+                    InvalidAlgorithmParameterException {
+        mFullRestoreToFileTask.restoreToFile(encryptedFile);
+        DecryptedChunkKvOutput decryptedChunkKvOutput = new DecryptedChunkKvOutput(mChunkHasher);
+        mBackupFileDecryptorTask.decryptFile(encryptedFile, decryptedChunkKvOutput);
+
+        BackupDataOutput backupDataOutput = new BackupDataOutput(output.getFileDescriptor());
+        for (KeyValuePairProto.KeyValuePair pair : decryptedChunkKvOutput.getPairs()) {
+            backupDataOutput.writeEntityHeader(pair.key, pair.value.length);
+            backupDataOutput.writeEntityData(pair.value, pair.value.length);
+        }
+    }
+}