/* * Copyright (C) 2015 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; import android.annotation.IntDef; import android.annotation.Nullable; import android.annotation.TestApi; import android.security.keymaster.KeymasterDefs; import android.system.keystore2.ResponseCode; import android.util.Log; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.util.HashMap; import java.util.Map; /** * Exception containing information about the failure at the Keystore / KeyMint layer while * generating or using a key. * * The public error codes indicate the cause of the error and the methods indicate whether * it's a system/key issue and whether re-trying the operation (with the same key or a new key) * is likely to succeed. */ public class KeyStoreException extends Exception { private static final String TAG = "KeyStoreException"; /** * This error code is for mapping errors that the caller will not know about. If the caller is * targeting an API level earlier than the one the error was introduced in, then the error will * be mapped to this one. * In API level 33 no errors map to this error. */ public static final int ERROR_OTHER = 1; /** * Indicating the key could not be used because the user needs to authenticate first. * See * {@link android.security.keystore.KeyGenParameterSpec.Builder#setUserAuthenticationRequired(boolean)}. */ public static final int ERROR_USER_AUTHENTICATION_REQUIRED = 2; /** * Indicating that {@code load()} has not been called on the Keystore instance, or an attempt * has been made to generate an authorization bound key while the user has not set a lock * screen knowledge factor (LSKF). Instruct the user to set an LSKF and retry. */ public static final int ERROR_KEYSTORE_UNINITIALIZED = 3; /** * An internal system error - refer to {@link #isTransientFailure()} to determine whether * re-trying the operation is likely to yield different results. */ public static final int ERROR_INTERNAL_SYSTEM_ERROR = 4; /** * The caller has requested key parameters or operation which are only available to system * or privileged apps. */ public static final int ERROR_PERMISSION_DENIED = 5; /** * The key the operation refers to doesn't exist. */ public static final int ERROR_KEY_DOES_NOT_EXIST = 6; /** * The key is corrupted and could not be recovered. */ public static final int ERROR_KEY_CORRUPTED = 7; /** * The error related to inclusion of device identifiers in the attestation record. */ public static final int ERROR_ID_ATTESTATION_FAILURE = 8; /** * The attestation challenge specified is too large. */ public static final int ERROR_ATTESTATION_CHALLENGE_TOO_LARGE = 9; /** * General error in the KeyMint layer. */ public static final int ERROR_KEYMINT_FAILURE = 10; /** * Failure in the Keystore layer. */ public static final int ERROR_KEYSTORE_FAILURE = 11; /** * The feature the caller is trying to use is not implemented by the underlying * KeyMint implementation. * This could happen when an unsupported algorithm is requested, or when trying to import * a key in a format other than raw or PKCS#8. */ public static final int ERROR_UNIMPLEMENTED = 12; /** * The feature the caller is trying to use is not compatible with the parameters used to * generate the key. For example, trying to use a key generated for a different signature * algorithm, or a digest not specified during key creation. * Another case is the attempt to generate a symmetric AES key and requesting key attestation. */ public static final int ERROR_INCORRECT_USAGE = 13; /** * The key is not currently valid: Either at has expired or it will be valid for use in the * future. */ public static final int ERROR_KEY_NOT_TEMPORALLY_VALID = 14; /** * The crypto object the caller has been using held a reference to a KeyMint operation that * has been evacuated (likely due to other concurrent operations taking place). * The caller should re-create the crypto object and try again. */ public static final int ERROR_KEY_OPERATION_EXPIRED = 15; /** * There are no keys available for attestation. * This error is returned only on devices that rely solely on remotely-provisioned keys (see * Remote Key Provisioning). * *
On such a device, if the caller requests key generation and includes an attestation * challenge (indicating key attestation is required), the error will be returned in one of * the following cases: *
This error is a transient one if the pool of remotely-provisioned keys has been * exhausted. However, if the device is not registered with the server, or the key * provisioning server refuses key issuance, this is a permanent error.
*/ public static final int ERROR_ATTESTATION_KEYS_UNAVAILABLE = 16; /** * This device requires a software upgrade to use the key provisioning server. The software * is outdated and this error is returned only on devices that rely solely on * remotely-provisioned keys (see Remote Key Provisioning). * * @hide */ public static final int ERROR_DEVICE_REQUIRES_UPGRADE_FOR_ATTESTATION = 17; /** @hide */ @Retention(RetentionPolicy.SOURCE) @IntDef(flag = true, prefix = {"ERROR_"}, value = { ERROR_OTHER, ERROR_USER_AUTHENTICATION_REQUIRED, ERROR_KEYSTORE_UNINITIALIZED, ERROR_INTERNAL_SYSTEM_ERROR, ERROR_PERMISSION_DENIED, ERROR_KEY_DOES_NOT_EXIST, ERROR_KEY_CORRUPTED, ERROR_ID_ATTESTATION_FAILURE, ERROR_ATTESTATION_CHALLENGE_TOO_LARGE, ERROR_KEYMINT_FAILURE, ERROR_KEYSTORE_FAILURE, ERROR_UNIMPLEMENTED, ERROR_INCORRECT_USAGE, ERROR_KEY_NOT_TEMPORALLY_VALID, ERROR_KEY_OPERATION_EXPIRED, ERROR_ATTESTATION_KEYS_UNAVAILABLE, ERROR_DEVICE_REQUIRES_UPGRADE_FOR_ATTESTATION, }) public @interface PublicErrorCode { } /** * Never re-try the operation that led to this error, since it's a permanent error. * * This value is always returned when {@link #isTransientFailure()} is {@code false}. */ public static final int RETRY_NEVER = 1; /** * Re-try the operation that led to this error with an exponential back-off delay. * The first delay should be between 5 to 30 seconds, and each subsequent re-try should double * the delay time. * * This value is returned when {@link #isTransientFailure()} is {@code true}. */ public static final int RETRY_WITH_EXPONENTIAL_BACKOFF = 2; /** * Re-try the operation that led to this error when the device regains connectivity. * Remote provisioning of keys requires reaching the remote server, and the device is * currently unable to due that due to lack of network connectivity. * * This value is returned when {@link #isTransientFailure()} is {@code true}. */ public static final int RETRY_WHEN_CONNECTIVITY_AVAILABLE = 3; /** * Re-try the operation that led to this error when the device has a software update * downloaded and on the next reboot. The Remote provisioning server recognizes * the device, but refuses issuance of attestation keys because it contains a software * version that could potentially be vulnerable and needs an update. Re-trying after the * device has upgraded and rebooted may alleviate the problem. * *This value is returned when {@link #isTransientFailure()} is {@code true}.
*/
public static final int RETRY_AFTER_NEXT_REBOOT = 4;
/** @hide */
@Retention(RetentionPolicy.SOURCE)
@IntDef(flag = true, prefix = {"RETRY_"}, value = {
RETRY_NEVER,
RETRY_WITH_EXPONENTIAL_BACKOFF,
RETRY_WHEN_CONNECTIVITY_AVAILABLE,
RETRY_AFTER_NEXT_REBOOT,
})
public @interface RetryPolicy {
}
// RKP-specific error information.
/**
* Remote provisioning of attestation keys has completed successfully.
* @hide */
public static final int RKP_SUCCESS = 0;
/**
* Remotely-provisioned keys are temporarily unavailable. This could be because of RPC
* error when talking to the remote provisioner or keys are being currently fetched and will
* be available soon.
* @hide */
public static final int RKP_TEMPORARILY_UNAVAILABLE = 1;
/**
* Permanent failure: The RKP server has declined issuance of keys to this device. Either
* because the device is not registered with the server or the server considers the device
* not to be trustworthy.
* @hide */
public static final int RKP_SERVER_REFUSED_ISSUANCE = 2;
/**
* The RKP server is unavailable due to lack of connectivity. The caller should re-try
* when the device has connectivity again.
* @hide */
public static final int RKP_FETCHING_PENDING_CONNECTIVITY = 3;
/**
* The RKP server recognizes the device, but the device may be running vulnerable software,
* and thus refusing issuance of RKP keys to it.
*
* @hide
*/
public static final int RKP_FETCHING_PENDING_SOFTWARE_REBOOT = 4;
// Constants for encoding information about the error encountered:
// Whether the error relates to the system state/implementation as a whole, or a specific key.
private static final int IS_SYSTEM_ERROR = 1 << 1;
// Whether the error is permanent.
private static final int IS_TRANSIENT_ERROR = 1 << 2;
// Whether the cause of the error is the user not having authenticated recently.
private static final int REQUIRES_USER_AUTHENTICATION = 1 << 3;
// The internal error code. NOT to be returned directly to callers or made part of the
// public API.
private final int mErrorCode;
// The Remote Key Provisioning status. Applicable if and only if {@link #mErrorCode} is equal
// to {@link ResponseCode.OUT_OF_KEYS}.
private final int mRkpStatus;
private static int initializeRkpStatusForRegularErrors(int errorCode) {
// Check if the system code mistakenly called a constructor of KeyStoreException with
// the OUT_OF_KEYS error code but without RKP status.
if (errorCode == ResponseCode.OUT_OF_KEYS) {
Log.e(TAG, "RKP error code without RKP status");
// Set RKP status to RKP_SERVER_REFUSED_ISSUANCE so that the caller never retries.
return RKP_SERVER_REFUSED_ISSUANCE;
} else {
return RKP_SUCCESS;
}
}
/**
* @hide
*/
public KeyStoreException(int errorCode, @Nullable String message) {
super(message);
mErrorCode = errorCode;
mRkpStatus = initializeRkpStatusForRegularErrors(errorCode);
}
/**
* @hide
*/
public KeyStoreException(int errorCode, @Nullable String message,
@Nullable String keystoreErrorMessage) {
super(message + " (internal Keystore code: " + errorCode + " message: "
+ keystoreErrorMessage + ")");
mErrorCode = errorCode;
mRkpStatus = initializeRkpStatusForRegularErrors(errorCode);
}
/**
* @hide
*/
public KeyStoreException(int errorCode, @Nullable String message, int rkpStatus) {
super(message);
mErrorCode = errorCode;
mRkpStatus = rkpStatus;
if (mErrorCode != ResponseCode.OUT_OF_KEYS) {
Log.e(TAG, "Providing RKP status for error code " + errorCode + " has no effect.");
}
}
/**
* Returns the internal error code. Only for use by the platform.
*
* @hide
*/
@TestApi
public int getErrorCode() {
return mErrorCode;
}
/**
* Returns one of the error codes exported by the class.
*
* @return a public error code
*/
@PublicErrorCode
public int getNumericErrorCode() {
PublicErrorInformation failureInfo = getErrorInformation(mErrorCode);
return failureInfo.errorCode;
}
/**
* Returns true if the failure is a transient failure - that is, performing the same operation
* again at a late time is likely to succeed.
*
* If {@link #isSystemError()} returns true, the transient nature of the failure relates to the
* device, otherwise relates to the key (so a permanent failure with an existing key likely
* requires creating another key to repeat the operation with).
*/
public boolean isTransientFailure() {
PublicErrorInformation failureInfo = getErrorInformation(mErrorCode);
// Special-case handling for RKP failures:
if (mRkpStatus != RKP_SUCCESS && mErrorCode == ResponseCode.OUT_OF_KEYS) {
switch (mRkpStatus) {
case RKP_TEMPORARILY_UNAVAILABLE:
case RKP_FETCHING_PENDING_CONNECTIVITY:
case RKP_FETCHING_PENDING_SOFTWARE_REBOOT:
return true;
case RKP_SERVER_REFUSED_ISSUANCE:
default:
return false;
}
}
return (failureInfo.indicators & IS_TRANSIENT_ERROR) != 0;
}
/**
* Indicates whether the failure is due to the device being locked.
*
* @return true if the key operation failed because the user has to authenticate
* (e.g. by unlocking the device).
*/
public boolean requiresUserAuthentication() {
PublicErrorInformation failureInfo = getErrorInformation(mErrorCode);
return (failureInfo.indicators & REQUIRES_USER_AUTHENTICATION) != 0;
}
/**
* Indicates whether the error related to the Keystore/KeyMint implementation and not
* a specific key.
*
* @return true if the error is related to the system, not the key in use. System
* errors indicate a feature isn't working, whereas key-related errors are likely
* to succeed with a new key.
*/
public boolean isSystemError() {
PublicErrorInformation failureInfo = getErrorInformation(mErrorCode);
return (failureInfo.indicators & IS_SYSTEM_ERROR) != 0;
}
/**
* Returns the re-try policy for transient failures. Valid only if
* {@link #isTransientFailure()} returns {@code True}.
*/
@RetryPolicy
public int getRetryPolicy() {
PublicErrorInformation failureInfo = getErrorInformation(mErrorCode);
// Special-case handling for RKP failures (To be removed in API 34)
if (mRkpStatus != RKP_SUCCESS) {
switch (mRkpStatus) {
case RKP_TEMPORARILY_UNAVAILABLE:
return RETRY_WITH_EXPONENTIAL_BACKOFF;
case RKP_FETCHING_PENDING_CONNECTIVITY:
return RETRY_WHEN_CONNECTIVITY_AVAILABLE;
case RKP_SERVER_REFUSED_ISSUANCE:
return RETRY_NEVER;
case RKP_FETCHING_PENDING_SOFTWARE_REBOOT:
return RETRY_AFTER_NEXT_REBOOT;
default:
return (failureInfo.indicators & IS_TRANSIENT_ERROR) != 0
? RETRY_WITH_EXPONENTIAL_BACKOFF : RETRY_NEVER;
}
}
switch (mErrorCode) {
case ResponseCode.OUT_OF_KEYS_REQUIRES_SYSTEM_UPGRADE:
return RETRY_AFTER_NEXT_REBOOT;
case ResponseCode.OUT_OF_KEYS_PENDING_INTERNET_CONNECTIVITY:
return RETRY_WHEN_CONNECTIVITY_AVAILABLE;
default:
return (failureInfo.indicators & IS_TRANSIENT_ERROR) != 0
? RETRY_WITH_EXPONENTIAL_BACKOFF : RETRY_NEVER;
}
}
@Override
public String toString() {
String errorCodes = String.format(" (public error code: %d internal Keystore code: %d)",
getNumericErrorCode(), mErrorCode);
return super.toString() + errorCodes;
}
private static PublicErrorInformation getErrorInformation(int internalErrorCode) {
PublicErrorInformation errorInfo = sErrorCodeToFailureInfo.get(internalErrorCode);
if (errorInfo != null) {
return errorInfo;
}
/**
* KeyStore/keymaster exception with positive error codes coming from the KeyStore and
* negative ones from keymaster.
* This is a safety fall-back: All error codes should be present in the map.
*/
if (internalErrorCode > 0) {
return GENERAL_KEYSTORE_ERROR;
} else {
return GENERAL_KEYMINT_ERROR;
}
}
private static final class PublicErrorInformation {
public final int indicators;
public final int errorCode;
PublicErrorInformation(int indicators, @PublicErrorCode int errorCode) {
this.indicators = indicators;
this.errorCode = errorCode;
}
}
private static final PublicErrorInformation GENERAL_KEYMINT_ERROR =
new PublicErrorInformation(0, ERROR_KEYMINT_FAILURE);
private static final PublicErrorInformation GENERAL_KEYSTORE_ERROR =
new PublicErrorInformation(0, ERROR_KEYSTORE_FAILURE);
private static final PublicErrorInformation KEYMINT_UNIMPLEMENTED_ERROR =
new PublicErrorInformation(IS_SYSTEM_ERROR, ERROR_UNIMPLEMENTED);
private static final PublicErrorInformation KEYMINT_RETRYABLE_ERROR =
new PublicErrorInformation(IS_SYSTEM_ERROR | IS_TRANSIENT_ERROR,
ERROR_KEYMINT_FAILURE);
private static final PublicErrorInformation KEYMINT_INCORRECT_USAGE_ERROR =
new PublicErrorInformation(0, ERROR_INCORRECT_USAGE);
private static final PublicErrorInformation KEYMINT_TEMPORAL_VALIDITY_ERROR =
new PublicErrorInformation(0, ERROR_KEY_NOT_TEMPORALLY_VALID);
private static final Map