| /* |
| * Copyright (C) 2017 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 android.security.keystore.recovery; |
| |
| import android.annotation.NonNull; |
| import android.annotation.Nullable; |
| import android.annotation.RequiresPermission; |
| import android.annotation.SystemApi; |
| import android.app.PendingIntent; |
| import android.content.Context; |
| import android.content.pm.PackageManager.NameNotFoundException; |
| import android.os.RemoteException; |
| import android.os.ServiceManager; |
| import android.os.ServiceSpecificException; |
| |
| import com.android.internal.widget.ILockSettings; |
| |
| import java.security.cert.CertificateException; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.Map; |
| |
| /** |
| * An assistant for generating {@link javax.crypto.SecretKey} instances that can be recovered by |
| * other Android devices belonging to the user. The exported keychain is protected by the user's |
| * lock screen. |
| * |
| * <p>The RecoveryController must be paired with a recovery agent. The recovery agent is responsible |
| * for transporting the keychain to remote trusted hardware. This hardware must prevent brute force |
| * attempts against the user's lock screen by limiting the number of allowed guesses (to, e.g., 10). |
| * After that number of incorrect guesses, the trusted hardware no longer allows access to the |
| * key chain. |
| * |
| * <p>For now only the recovery agent itself is able to create keys, so it is expected that the |
| * recovery agent is itself the system app. |
| * |
| * <p>A recovery agent requires the privileged permission |
| * {@code android.Manifest.permission#RECOVER_KEYSTORE}. |
| * |
| * @hide |
| */ |
| @SystemApi |
| public class RecoveryController { |
| private static final String TAG = "RecoveryController"; |
| |
| /** Key has been successfully synced. */ |
| public static final int RECOVERY_STATUS_SYNCED = 0; |
| /** Waiting for recovery agent to sync the key. */ |
| public static final int RECOVERY_STATUS_SYNC_IN_PROGRESS = 1; |
| /** Recovery account is not available. */ |
| public static final int RECOVERY_STATUS_MISSING_ACCOUNT = 2; |
| /** Key cannot be synced. */ |
| public static final int RECOVERY_STATUS_PERMANENT_FAILURE = 3; |
| |
| /** |
| * Failed because no snapshot is yet pending to be synced for the user. |
| * |
| * @hide |
| */ |
| public static final int ERROR_NO_SNAPSHOT_PENDING = 21; |
| |
| /** |
| * Failed due to an error internal to the recovery service. This is unexpected and indicates |
| * either a problem with the logic in the service, or a problem with a dependency of the |
| * service (such as AndroidKeyStore). |
| * |
| * @hide |
| */ |
| public static final int ERROR_SERVICE_INTERNAL_ERROR = 22; |
| |
| /** |
| * Failed because the user does not have a lock screen set. |
| * |
| * @hide |
| */ |
| public static final int ERROR_INSECURE_USER = 23; |
| |
| /** |
| * Error thrown when attempting to use a recovery session that has since been closed. |
| * |
| * @hide |
| */ |
| public static final int ERROR_SESSION_EXPIRED = 24; |
| |
| /** |
| * Failed because the provided certificate was not a valid X509 certificate. |
| * |
| * @hide |
| */ |
| public static final int ERROR_BAD_CERTIFICATE_FORMAT = 25; |
| |
| /** |
| * Error thrown if decryption failed. This might be because the tag is wrong, the key is wrong, |
| * the data has become corrupted, the data has been tampered with, etc. |
| * |
| * @hide |
| */ |
| public static final int ERROR_DECRYPTION_FAILED = 26; |
| |
| |
| private final ILockSettings mBinder; |
| |
| private RecoveryController(ILockSettings binder) { |
| mBinder = binder; |
| } |
| |
| /** |
| * Internal method used by {@code RecoverySession}. |
| * |
| * @hide |
| */ |
| ILockSettings getBinder() { |
| return mBinder; |
| } |
| |
| /** |
| * Gets a new instance of the class. |
| */ |
| public static RecoveryController getInstance(Context context) { |
| ILockSettings lockSettings = |
| ILockSettings.Stub.asInterface(ServiceManager.getService("lock_settings")); |
| return new RecoveryController(lockSettings); |
| } |
| |
| /** |
| * Initializes key recovery service for the calling application. RecoveryController |
| * randomly chooses one of the keys from the list and keeps it to use for future key export |
| * operations. Collection of all keys in the list must be signed by the provided {@code |
| * rootCertificateAlias}, which must also be present in the list of root certificates |
| * preinstalled on the device. The random selection allows RecoveryController to select |
| * which of a set of remote recovery service devices will be used. |
| * |
| * <p>In addition, RecoveryController enforces a delay of three months between |
| * consecutive initialization attempts, to limit the ability of an attacker to often switch |
| * remote recovery devices and significantly increase number of recovery attempts. |
| * |
| * @param rootCertificateAlias alias of a root certificate preinstalled on the device |
| * @param signedPublicKeyList binary blob a list of X509 certificates and signature |
| * @throws CertificateException if the {@code signedPublicKeyList} is in a bad format. |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) |
| public void initRecoveryService( |
| @NonNull String rootCertificateAlias, @NonNull byte[] signedPublicKeyList) |
| throws CertificateException, InternalRecoveryServiceException { |
| try { |
| mBinder.initRecoveryService(rootCertificateAlias, signedPublicKeyList); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| if (e.errorCode == ERROR_BAD_CERTIFICATE_FORMAT) { |
| throw new CertificateException(e.getMessage()); |
| } |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Returns data necessary to store all recoverable keys. Key material is |
| * encrypted with user secret and recovery public key. |
| * |
| * @return Data necessary to recover keystore. |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) |
| public @NonNull KeyChainSnapshot getRecoveryData() |
| throws InternalRecoveryServiceException { |
| try { |
| return mBinder.getRecoveryData(/*account=*/ new byte[]{}); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| if (e.errorCode == ERROR_NO_SNAPSHOT_PENDING) { |
| return null; |
| } |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Sets a listener which notifies recovery agent that new recovery snapshot is available. {@link |
| * #getRecoveryData} can be used to get the snapshot. Note that every recovery agent can have at |
| * most one registered listener at any time. |
| * |
| * @param intent triggered when new snapshot is available. Unregisters listener if the value is |
| * {@code null}. |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) |
| public void setSnapshotCreatedPendingIntent(@Nullable PendingIntent intent) |
| throws InternalRecoveryServiceException { |
| try { |
| mBinder.setSnapshotCreatedPendingIntent(intent); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Server parameters used to generate new recovery key blobs. This value will be included in |
| * {@code KeyChainSnapshot.getEncryptedRecoveryKeyBlob()}. The same value must be included |
| * in vaultParams {@link #startRecoverySession} |
| * |
| * @param serverParams included in recovery key blob. |
| * @see #getRecoveryData |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) |
| public void setServerParams(byte[] serverParams) throws InternalRecoveryServiceException { |
| try { |
| mBinder.setServerParams(serverParams); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Gets aliases of recoverable keys for the application. |
| * |
| * @param packageName which recoverable keys' aliases will be returned. |
| * |
| * @return {@code List} of all aliases. |
| */ |
| public List<String> getAliases(@Nullable String packageName) |
| throws InternalRecoveryServiceException { |
| try { |
| // TODO: update aidl |
| Map<String, Integer> allStatuses = mBinder.getRecoveryStatus(packageName); |
| return new ArrayList<>(allStatuses.keySet()); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Updates recovery status for given key. It is used to notify keystore that key was |
| * successfully stored on the server or there were an error. Application can check this value |
| * using {@code getRecoveyStatus}. |
| * |
| * @param packageName Application whose recoverable key's status are to be updated. |
| * @param alias Application-specific key alias. |
| * @param status Status specific to recovery agent. |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) |
| public void setRecoveryStatus( |
| @NonNull String packageName, String alias, int status) |
| throws NameNotFoundException, InternalRecoveryServiceException { |
| try { |
| // TODO: update aidl |
| String[] aliases = alias == null ? null : new String[]{alias}; |
| mBinder.setRecoveryStatus(packageName, aliases, status); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Returns recovery status for Application's KeyStore key. |
| * Negative status values are reserved for recovery agent specific codes. List of common codes: |
| * |
| * <ul> |
| * <li>{@link #RECOVERY_STATUS_SYNCED} |
| * <li>{@link #RECOVERY_STATUS_SYNC_IN_PROGRESS} |
| * <li>{@link #RECOVERY_STATUS_MISSING_ACCOUNT} |
| * <li>{@link #RECOVERY_STATUS_PERMANENT_FAILURE} |
| * </ul> |
| * |
| * @param packageName Application whose recoverable key status is returned. |
| * @param alias Application-specific key alias. |
| * @return Recovery status. |
| * @see #setRecoveryStatus |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| public int getRecoveryStatus(String packageName, String alias) |
| throws InternalRecoveryServiceException { |
| try { |
| // TODO: update aidl |
| Map<String, Integer> allStatuses = mBinder.getRecoveryStatus(packageName); |
| Integer status = allStatuses.get(alias); |
| if (status == null) { |
| return RecoveryController.RECOVERY_STATUS_PERMANENT_FAILURE; |
| } else { |
| return status; |
| } |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Specifies a set of secret types used for end-to-end keystore encryption. Knowing all of them |
| * is necessary to recover data. |
| * |
| * @param secretTypes {@link KeyChainProtectionParams#TYPE_LOCKSCREEN} or {@link |
| * KeyChainProtectionParams#TYPE_CUSTOM_PASSWORD} |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| public void setRecoverySecretTypes( |
| @NonNull @KeyChainProtectionParams.UserSecretType int[] secretTypes) |
| throws InternalRecoveryServiceException { |
| try { |
| mBinder.setRecoverySecretTypes(secretTypes); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Defines a set of secret types used for end-to-end keystore encryption. Knowing all of them is |
| * necessary to generate KeyChainSnapshot. |
| * |
| * @return list of recovery secret types |
| * @see KeyChainSnapshot |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| public @NonNull @KeyChainProtectionParams.UserSecretType int[] getRecoverySecretTypes() |
| throws InternalRecoveryServiceException { |
| try { |
| return mBinder.getRecoverySecretTypes(); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Returns a list of recovery secret types, necessary to create a pending recovery snapshot. |
| * When user enters a secret of a pending type {@link #recoverySecretAvailable} should be |
| * called. |
| * |
| * @return list of recovery secret types |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| @NonNull |
| public @KeyChainProtectionParams.UserSecretType int[] getPendingRecoverySecretTypes() |
| throws InternalRecoveryServiceException { |
| try { |
| return mBinder.getPendingRecoverySecretTypes(); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Method notifies KeyStore that a user-generated secret is available. This method generates a |
| * symmetric session key which a trusted remote device can use to return a recovery key. Caller |
| * should use {@link KeyChainProtectionParams#clearSecret} to override the secret value in |
| * memory. |
| * |
| * @param recoverySecret user generated secret together with parameters necessary to regenerate |
| * it on a new device. |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| public void recoverySecretAvailable(@NonNull KeyChainProtectionParams recoverySecret) |
| throws InternalRecoveryServiceException { |
| try { |
| mBinder.recoverySecretAvailable(recoverySecret); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Generates a AES256/GCM/NoPADDING key called {@code alias} and loads it into the recoverable |
| * key store. Returns the raw material of the key. |
| * |
| * @param alias The key alias. |
| * @param account The account associated with the key |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| * @throws LockScreenRequiredException if the user has not set a lock screen. This is required |
| * to generate recoverable keys, as the snapshots are encrypted using a key derived from the |
| * lock screen. |
| */ |
| public byte[] generateAndStoreKey(@NonNull String alias, byte[] account) |
| throws InternalRecoveryServiceException, LockScreenRequiredException { |
| try { |
| // TODO: add account |
| return mBinder.generateAndStoreKey(alias); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| if (e.errorCode == ERROR_INSECURE_USER) { |
| throw new LockScreenRequiredException(e.getMessage()); |
| } |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Removes a key called {@code alias} from the recoverable key store. |
| * |
| * @param alias The key alias. |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| public void removeKey(@NonNull String alias) throws InternalRecoveryServiceException { |
| try { |
| mBinder.removeKey(alias); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| InternalRecoveryServiceException wrapUnexpectedServiceSpecificException( |
| ServiceSpecificException e) { |
| if (e.errorCode == ERROR_SERVICE_INTERNAL_ERROR) { |
| return new InternalRecoveryServiceException(e.getMessage()); |
| } |
| |
| // Should never happen. If it does, it's a bug, and we need to update how the method that |
| // called this throws its exceptions. |
| return new InternalRecoveryServiceException("Unexpected error code for method: " |
| + e.errorCode, e); |
| } |
| } |