| /* |
| * 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; |
| |
| import android.annotation.NonNull; |
| import android.annotation.Nullable; |
| import android.app.PendingIntent; |
| import android.content.pm.PackageManager.NameNotFoundException; |
| import android.os.RemoteException; |
| import android.os.ServiceManager; |
| import android.os.ServiceSpecificException; |
| import android.util.Log; |
| |
| import com.android.internal.widget.ILockSettings; |
| |
| 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 |
| */ |
| 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; |
| } |
| |
| /** |
| * Gets a new instance of the class. |
| */ |
| public static RecoveryController getInstance() { |
| 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 BadCertificateFormatException if the {@code signedPublicKeyList} is in a bad format. |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| public void initRecoveryService( |
| @NonNull String rootCertificateAlias, @NonNull byte[] signedPublicKeyList) |
| throws BadCertificateFormatException, InternalRecoveryServiceException { |
| try { |
| mBinder.initRecoveryService(rootCertificateAlias, signedPublicKeyList); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| if (e.errorCode == ERROR_BAD_CERTIFICATE_FORMAT) { |
| throw new BadCertificateFormatException(e.getMessage()); |
| } |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Returns data necessary to store all recoverable keys for given account. Key material is |
| * encrypted with user secret and recovery public key. |
| * |
| * @param account specific to Recovery agent. |
| * @return Data necessary to recover keystore. |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| public @NonNull KeychainSnapshot getRecoveryData(@NonNull byte[] account) |
| throws InternalRecoveryServiceException { |
| try { |
| return mBinder.getRecoveryData(account); |
| } 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. |
| */ |
| public void setSnapshotCreatedPendingIntent(@Nullable PendingIntent intent) |
| throws InternalRecoveryServiceException { |
| try { |
| mBinder.setSnapshotCreatedPendingIntent(intent); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Returns a map from recovery agent accounts to corresponding KeyStore recovery snapshot |
| * version. Version zero is used, if no snapshots were created for the account. |
| * |
| * @return Map from recovery agent accounts to snapshot versions. |
| * @see KeychainSnapshot#getSnapshotVersion |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| public @NonNull Map<byte[], Integer> getRecoverySnapshotVersions() |
| throws InternalRecoveryServiceException { |
| try { |
| // IPC doesn't support generic Maps. |
| @SuppressWarnings("unchecked") |
| Map<byte[], Integer> result = |
| (Map<byte[], Integer>) mBinder.getRecoverySnapshotVersions(); |
| return result; |
| } 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. |
| */ |
| public void setServerParams(byte[] serverParams) throws InternalRecoveryServiceException { |
| try { |
| mBinder.setServerParams(serverParams); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Updates recovery status for given keys. 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 keys' statuses are to be updated. |
| * @param aliases List of application-specific key aliases. If the array is empty, updates the |
| * status for all existing recoverable keys. |
| * @param status Status specific to recovery agent. |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| public void setRecoveryStatus( |
| @NonNull String packageName, @Nullable String[] aliases, int status) |
| throws NameNotFoundException, InternalRecoveryServiceException { |
| try { |
| mBinder.setRecoveryStatus(packageName, aliases, status); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Returns a {@code Map} from Application's KeyStore key aliases to their recovery status. |
| * 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> |
| * |
| * @return {@code Map} from KeyStore alias to recovery status. |
| * @see #setRecoveryStatus |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| public Map<String, Integer> getRecoveryStatus() throws InternalRecoveryServiceException { |
| try { |
| // IPC doesn't support generic Maps. |
| @SuppressWarnings("unchecked") |
| Map<String, Integer> result = |
| (Map<String, Integer>) mBinder.getRecoveryStatus(/*packageName=*/ null); |
| return result; |
| } 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); |
| } |
| } |
| |
| /** |
| * Initializes recovery session and returns a blob with proof of recovery secrets possession. |
| * The method generates symmetric key for a session, which trusted remote device can use to |
| * return recovery key. |
| * |
| * @param verifierPublicKey Encoded {@code java.security.cert.X509Certificate} with Public key |
| * used to create the recovery blob on the source device. |
| * Keystore will verify the certificate using root of trust. |
| * @param vaultParams Must match the parameters in the corresponding field in the recovery blob. |
| * Used to limit number of guesses. |
| * @param vaultChallenge Data passed from server for this recovery session and used to prevent |
| * replay attacks |
| * @param secrets Secrets provided by user, the method only uses type and secret fields. |
| * @return The recovery claim. Claim provides a b binary blob with recovery claim. It is |
| * encrypted with verifierPublicKey and contains a proof of user secrets, session symmetric |
| * key and parameters necessary to identify the counter with the number of failed recovery |
| * attempts. |
| * @throws BadCertificateFormatException if the {@code verifierPublicKey} is in an incorrect |
| * format. |
| * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery |
| * service. |
| */ |
| @NonNull public RecoveryClaim startRecoverySession( |
| @NonNull byte[] verifierPublicKey, |
| @NonNull byte[] vaultParams, |
| @NonNull byte[] vaultChallenge, |
| @NonNull List<KeychainProtectionParams> secrets) |
| throws BadCertificateFormatException, InternalRecoveryServiceException { |
| try { |
| RecoverySession recoverySession = RecoverySession.newInstance(this); |
| byte[] recoveryClaim = |
| mBinder.startRecoverySession( |
| recoverySession.getSessionId(), |
| verifierPublicKey, |
| vaultParams, |
| vaultChallenge, |
| secrets); |
| return new RecoveryClaim(recoverySession, recoveryClaim); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| if (e.errorCode == ERROR_BAD_CERTIFICATE_FORMAT) { |
| throw new BadCertificateFormatException(e.getMessage()); |
| } |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Imports keys. |
| * |
| * @param session Related recovery session, as originally created by invoking |
| * {@link #startRecoverySession(byte[], byte[], byte[], List)}. |
| * @param recoveryKeyBlob Recovery blob encrypted by symmetric key generated for this session. |
| * @param applicationKeys Application keys. Key material can be decrypted using recoveryKeyBlob |
| * and session. KeyStore only uses package names from the application info in {@link |
| * WrappedApplicationKey}. Caller is responsibility to perform certificates check. |
| * @return Map from alias to raw key material. |
| * @throws SessionExpiredException if {@code session} has since been closed. |
| * @throws DecryptionFailedException if unable to decrypt the snapshot. |
| * @throws InternalRecoveryServiceException if an error occurs internal to the recovery service. |
| */ |
| public Map<String, byte[]> recoverKeys( |
| @NonNull RecoverySession session, |
| @NonNull byte[] recoveryKeyBlob, |
| @NonNull List<WrappedApplicationKey> applicationKeys) |
| throws SessionExpiredException, DecryptionFailedException, |
| InternalRecoveryServiceException { |
| try { |
| return (Map<String, byte[]>) mBinder.recoverKeys( |
| session.getSessionId(), recoveryKeyBlob, applicationKeys); |
| } catch (RemoteException e) { |
| throw e.rethrowFromSystemServer(); |
| } catch (ServiceSpecificException e) { |
| if (e.errorCode == ERROR_DECRYPTION_FAILED) { |
| throw new DecryptionFailedException(e.getMessage()); |
| } |
| if (e.errorCode == ERROR_SESSION_EXPIRED) { |
| throw new SessionExpiredException(e.getMessage()); |
| } |
| throw wrapUnexpectedServiceSpecificException(e); |
| } |
| } |
| |
| /** |
| * Deletes all data associated with {@code session}. Should not be invoked directly but via |
| * {@link RecoverySession#close()}. |
| * |
| * @hide |
| */ |
| void closeSession(RecoverySession session) { |
| try { |
| mBinder.closeSession(session.getSessionId()); |
| } catch (RemoteException | ServiceSpecificException e) { |
| Log.e(TAG, "Unexpected error trying to close session", e); |
| } |
| } |
| |
| /** |
| * Generates a key called {@code alias} and loads it into the recoverable key store. Returns the |
| * raw material of the key. |
| * |
| * @param alias The key alias. |
| * @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) |
| throws InternalRecoveryServiceException, LockScreenRequiredException { |
| try { |
| 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); |
| } |
| } |
| |
| private 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); |
| } |
| } |