keystore/keymaster_enforcement.cpp - platform/system/security - Gitiles

 /*
  * Copyright (C) 2014 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.
  */

 #define LOG_TAG "keystore"

 #include "keymaster_enforcement.h"

 #include <assert.h>
 #include <inttypes.h>
 #include <limits.h>
 #include <string.h>

 #include <openssl/evp.h>

 #include <hardware/hw_auth_token.h>
 #include <log/log.h>

 #include <list>

 #include <keystore/keystore_hidl_support.h>

 namespace keystore {

 bool is_public_key_algorithm(const AuthorizationSet& auth_set) {
     auto algorithm = auth_set.GetTagValue(TAG_ALGORITHM);
     return algorithm.isOk() &&
            (algorithm.value() == Algorithm::RSA || algorithm.value() == Algorithm::EC);
 }

 static ErrorCode authorized_purpose(const KeyPurpose purpose, const AuthorizationSet& auth_set) {
     switch (purpose) {
     case KeyPurpose::VERIFY:
     case KeyPurpose::ENCRYPT:
     case KeyPurpose::SIGN:
     case KeyPurpose::DECRYPT:
         if (auth_set.Contains(TAG_PURPOSE, purpose)) return ErrorCode::OK;
         return ErrorCode::INCOMPATIBLE_PURPOSE;

     default:
         return ErrorCode::UNSUPPORTED_PURPOSE;
     }
 }

 inline bool is_origination_purpose(KeyPurpose purpose) {
     return purpose == KeyPurpose::ENCRYPT || purpose == KeyPurpose::SIGN;
 }

 inline bool is_usage_purpose(KeyPurpose purpose) {
     return purpose == KeyPurpose::DECRYPT || purpose == KeyPurpose::VERIFY;
 }

 KeymasterEnforcement::KeymasterEnforcement(uint32_t max_access_time_map_size,
                                            uint32_t max_access_count_map_size)
     : access_time_map_(max_access_time_map_size), access_count_map_(max_access_count_map_size) {}

 KeymasterEnforcement::~KeymasterEnforcement() {
 }

 ErrorCode KeymasterEnforcement::AuthorizeOperation(const KeyPurpose purpose, const km_id_t keyid,
                                                    const AuthorizationSet& auth_set,
                                                    const AuthorizationSet& operation_params,
                                                    const HardwareAuthToken& auth_token,
                                                    uint64_t op_handle, bool is_begin_operation) {
     if (is_public_key_algorithm(auth_set)) {
         switch (purpose) {
         case KeyPurpose::ENCRYPT:
         case KeyPurpose::VERIFY:
             /* Public key operations are always authorized. */
             return ErrorCode::OK;

         case KeyPurpose::DECRYPT:
         case KeyPurpose::SIGN:
             break;

         case KeyPurpose::WRAP_KEY:
             return ErrorCode::INCOMPATIBLE_PURPOSE;
         };
     };

     if (is_begin_operation)
         return AuthorizeBegin(purpose, keyid, auth_set, operation_params, auth_token);
     else
         return AuthorizeUpdateOrFinish(auth_set, auth_token, op_handle);
 }

 // For update and finish the only thing to check is user authentication, and then only if it's not
 // timeout-based.
 ErrorCode KeymasterEnforcement::AuthorizeUpdateOrFinish(const AuthorizationSet& auth_set,
                                                         const HardwareAuthToken& auth_token,
                                                         uint64_t op_handle) {
     int auth_type_index = -1;
     for (size_t pos = 0; pos < auth_set.size(); ++pos) {
         switch (auth_set[pos].tag) {
         case Tag::NO_AUTH_REQUIRED:
         case Tag::AUTH_TIMEOUT:
             // If no auth is required or if auth is timeout-based, we have nothing to check.
             return ErrorCode::OK;

         case Tag::USER_AUTH_TYPE:
             auth_type_index = pos;
             break;

         default:
             break;
         }
     }

     // Note that at this point we should be able to assume that authentication is required, because
     // authentication is required if KM_TAG_NO_AUTH_REQUIRED is absent.  However, there are legacy
     // keys which have no authentication-related tags, so we assume that absence is equivalent to
     // presence of KM_TAG_NO_AUTH_REQUIRED.
     //
     // So, if we found KM_TAG_USER_AUTH_TYPE or if we find KM_TAG_USER_SECURE_ID then authentication
     // is required.  If we find neither, then we assume authentication is not required and return
     // success.
     bool authentication_required = (auth_type_index != -1);
     for (auto& param : auth_set) {
         auto user_secure_id = authorizationValue(TAG_USER_SECURE_ID, param);
         if (user_secure_id.isOk()) {
             authentication_required = true;
             int auth_timeout_index = -1;
             if (auth_token.mac.size() &&
                 AuthTokenMatches(auth_set, auth_token, user_secure_id.value(), auth_type_index,
                                  auth_timeout_index, op_handle, false /* is_begin_operation */))
                 return ErrorCode::OK;
         }
     }

     if (authentication_required) return ErrorCode::KEY_USER_NOT_AUTHENTICATED;

     return ErrorCode::OK;
 }

 ErrorCode KeymasterEnforcement::AuthorizeBegin(const KeyPurpose purpose, const km_id_t keyid,
                                                const AuthorizationSet& auth_set,
                                                const AuthorizationSet& operation_params,
                                                NullOr<const HardwareAuthToken&> auth_token) {
     // Find some entries that may be needed to handle KM_TAG_USER_SECURE_ID
     int auth_timeout_index = -1;
     int auth_type_index = -1;
     int no_auth_required_index = -1;
     for (size_t pos = 0; pos < auth_set.size(); ++pos) {
         switch (auth_set[pos].tag) {
         case Tag::AUTH_TIMEOUT:
             auth_timeout_index = pos;
             break;
         case Tag::USER_AUTH_TYPE:
             auth_type_index = pos;
             break;
         case Tag::NO_AUTH_REQUIRED:
             no_auth_required_index = pos;
             break;
         default:
             break;
         }
     }

     ErrorCode error = authorized_purpose(purpose, auth_set);
     if (error != ErrorCode::OK) return error;

     // If successful, and if key has a min time between ops, this will be set to the time limit
     uint32_t min_ops_timeout = UINT32_MAX;

     bool update_access_count = false;
     bool caller_nonce_authorized_by_key = false;
     bool authentication_required = false;
     bool auth_token_matched = false;
     bool unlocked_device_required = false;
     int32_t user_id = -1;

     for (auto& param : auth_set) {

         // KM_TAG_PADDING_OLD and KM_TAG_DIGEST_OLD aren't actually members of the enum, so we can't
         // switch on them.  There's nothing to validate for them, though, so just ignore them.
         if (int32_t(param.tag) == KM_TAG_PADDING_OLD || int32_t(param.tag) == KM_TAG_DIGEST_OLD)
             continue;

         switch (param.tag) {

         case Tag::ACTIVE_DATETIME: {
             auto date = authorizationValue(TAG_ACTIVE_DATETIME, param);
             if (date.isOk() && !activation_date_valid(date.value()))
                 return ErrorCode::KEY_NOT_YET_VALID;
             break;
         }
         case Tag::ORIGINATION_EXPIRE_DATETIME: {
             auto date = authorizationValue(TAG_ORIGINATION_EXPIRE_DATETIME, param);
             if (is_origination_purpose(purpose) && date.isOk() &&
                 expiration_date_passed(date.value()))
                 return ErrorCode::KEY_EXPIRED;
             break;
         }
         case Tag::USAGE_EXPIRE_DATETIME: {
             auto date = authorizationValue(TAG_USAGE_EXPIRE_DATETIME, param);
             if (is_usage_purpose(purpose) && date.isOk() && expiration_date_passed(date.value()))
                 return ErrorCode::KEY_EXPIRED;
             break;
         }
         case Tag::MIN_SECONDS_BETWEEN_OPS: {
             auto min_ops_timeout = authorizationValue(TAG_MIN_SECONDS_BETWEEN_OPS, param);
             if (min_ops_timeout.isOk() && !MinTimeBetweenOpsPassed(min_ops_timeout.value(), keyid))
                 return ErrorCode::KEY_RATE_LIMIT_EXCEEDED;
             break;
         }
         case Tag::MAX_USES_PER_BOOT: {
             auto max_users = authorizationValue(TAG_MAX_USES_PER_BOOT, param);
             update_access_count = true;
             if (max_users.isOk() && !MaxUsesPerBootNotExceeded(keyid, max_users.value()))
                 return ErrorCode::KEY_MAX_OPS_EXCEEDED;
             break;
         }
         case Tag::USER_SECURE_ID:
             if (no_auth_required_index != -1) {
                 // Key has both KM_TAG_USER_SECURE_ID and KM_TAG_NO_AUTH_REQUIRED
                 return ErrorCode::INVALID_KEY_BLOB;
             }

             if (auth_timeout_index != -1) {
                 auto secure_id = authorizationValue(TAG_USER_SECURE_ID, param);
                 authentication_required = true;
                 if (secure_id.isOk() && auth_token.isOk() &&
                     AuthTokenMatches(auth_set, auth_token.value(), secure_id.value(),
                                      auth_type_index, auth_timeout_index, 0 /* op_handle */,
                                      true /* is_begin_operation */))
                     auth_token_matched = true;
             }
             break;

         case Tag::USER_ID:
             user_id = authorizationValue(TAG_USER_ID, param).value();
             break;

         case Tag::CALLER_NONCE:
             caller_nonce_authorized_by_key = true;
             break;

         case Tag::UNLOCKED_DEVICE_REQUIRED:
             unlocked_device_required = true;
             break;

         /* Tags should never be in key auths. */
         case Tag::INVALID:
         case Tag::ROOT_OF_TRUST:
         case Tag::APPLICATION_DATA:
         case Tag::ATTESTATION_CHALLENGE:
         case Tag::ATTESTATION_APPLICATION_ID:
         case Tag::ATTESTATION_ID_BRAND:
         case Tag::ATTESTATION_ID_DEVICE:
         case Tag::ATTESTATION_ID_PRODUCT:
         case Tag::ATTESTATION_ID_SERIAL:
         case Tag::ATTESTATION_ID_IMEI:
         case Tag::ATTESTATION_ID_MEID:
         case Tag::ATTESTATION_ID_MANUFACTURER:
         case Tag::ATTESTATION_ID_MODEL:
             return ErrorCode::INVALID_KEY_BLOB;

         /* Tags used for cryptographic parameters in keygen.  Nothing to enforce. */
         case Tag::PURPOSE:
         case Tag::ALGORITHM:
         case Tag::KEY_SIZE:
         case Tag::BLOCK_MODE:
         case Tag::DIGEST:
         case Tag::MAC_LENGTH:
         case Tag::PADDING:
         case Tag::NONCE:
         case Tag::MIN_MAC_LENGTH:
         case Tag::EC_CURVE:

         /* Tags not used for operations. */
         case Tag::BLOB_USAGE_REQUIREMENTS:

         /* Algorithm specific parameters not used for access control. */
         case Tag::RSA_PUBLIC_EXPONENT:

         /* Informational tags. */
         case Tag::CREATION_DATETIME:
         case Tag::ORIGIN:
         case Tag::ROLLBACK_RESISTANCE:

         /* Tags handled when KM_TAG_USER_SECURE_ID is handled */
         case Tag::NO_AUTH_REQUIRED:
         case Tag::USER_AUTH_TYPE:
         case Tag::AUTH_TIMEOUT:

         /* Tag to provide data to operations. */
         case Tag::ASSOCIATED_DATA:

         /* Tags that are implicitly verified by secure side */
         case Tag::APPLICATION_ID:
         case Tag::BOOT_PATCHLEVEL:
         case Tag::OS_PATCHLEVEL:
         case Tag::OS_VERSION:
         case Tag::TRUSTED_USER_PRESENCE_REQUIRED:
         case Tag::VENDOR_PATCHLEVEL:

         /* TODO(swillden): Handle these */
         case Tag::INCLUDE_UNIQUE_ID:
         case Tag::UNIQUE_ID:
         case Tag::RESET_SINCE_ID_ROTATION:
         case Tag::ALLOW_WHILE_ON_BODY:
         case Tag::HARDWARE_TYPE:
         case Tag::TRUSTED_CONFIRMATION_REQUIRED:
         case Tag::CONFIRMATION_TOKEN:
             break;

         case Tag::BOOTLOADER_ONLY:
             return ErrorCode::INVALID_KEY_BLOB;
         }
     }

     if (unlocked_device_required && is_device_locked(user_id)) {
         switch (purpose) {
         case KeyPurpose::ENCRYPT:
         case KeyPurpose::VERIFY:
             /* These are okay */
             break;
         case KeyPurpose::DECRYPT:
         case KeyPurpose::SIGN:
         case KeyPurpose::WRAP_KEY:
             return ErrorCode::DEVICE_LOCKED;
         };
     }

     if (authentication_required && !auth_token_matched) {
         ALOGE("Auth required but no matching auth token found");
         return ErrorCode::KEY_USER_NOT_AUTHENTICATED;
     }

     if (!caller_nonce_authorized_by_key && is_origination_purpose(purpose) &&
         operation_params.Contains(Tag::NONCE))
         return ErrorCode::CALLER_NONCE_PROHIBITED;

     if (min_ops_timeout != UINT32_MAX) {
         if (!access_time_map_.UpdateKeyAccessTime(keyid, get_current_time(), min_ops_timeout)) {
             ALOGE("Rate-limited keys table full.  Entries will time out.");
             return ErrorCode::TOO_MANY_OPERATIONS;
         }
     }

     if (update_access_count) {
         if (!access_count_map_.IncrementKeyAccessCount(keyid)) {
             ALOGE("Usage count-limited keys table full, until reboot.");
             return ErrorCode::TOO_MANY_OPERATIONS;
         }
     }

     return ErrorCode::OK;
 }

 class EvpMdCtx {
   public:
     EvpMdCtx() { EVP_MD_CTX_init(&ctx_); }
     ~EvpMdCtx() { EVP_MD_CTX_cleanup(&ctx_); }

     EVP_MD_CTX* get() { return &ctx_; }

   private:
     EVP_MD_CTX ctx_;
 };

 /* static */
 std::optional<km_id_t> KeymasterEnforcement::CreateKeyId(const hidl_vec<uint8_t>& key_blob) {
     EvpMdCtx ctx;
     km_id_t keyid;

     uint8_t hash[EVP_MAX_MD_SIZE];
     unsigned int hash_len;
     if (EVP_DigestInit_ex(ctx.get(), EVP_sha256(), nullptr /* ENGINE */) &&
         EVP_DigestUpdate(ctx.get(), &key_blob[0], key_blob.size()) &&
         EVP_DigestFinal_ex(ctx.get(), hash, &hash_len)) {
         assert(hash_len >= sizeof(keyid));
         memcpy(&keyid, hash, sizeof(keyid));
         return keyid;
     }

     return {};
 }

 bool KeymasterEnforcement::MinTimeBetweenOpsPassed(uint32_t min_time_between, const km_id_t keyid) {
     uint32_t last_access_time;
     if (!access_time_map_.LastKeyAccessTime(keyid, &last_access_time)) return true;
     return min_time_between <= static_cast<int64_t>(get_current_time()) - last_access_time;
 }

 bool KeymasterEnforcement::MaxUsesPerBootNotExceeded(const km_id_t keyid, uint32_t max_uses) {
     uint32_t key_access_count;
     if (!access_count_map_.KeyAccessCount(keyid, &key_access_count)) return true;
     return key_access_count < max_uses;
 }

 template <typename IntType, uint32_t byteOrder> struct choose_hton;

 template <typename IntType> struct choose_hton<IntType, __ORDER_LITTLE_ENDIAN__> {
     inline static IntType hton(const IntType& value) {
         IntType result = 0;
         const unsigned char* inbytes = reinterpret_cast<const unsigned char*>(&value);
         unsigned char* outbytes = reinterpret_cast<unsigned char*>(&result);
         for (int i = sizeof(IntType) - 1; i >= 0; --i) {
             *(outbytes++) = inbytes[i];
         }
         return result;
     }
 };

 template <typename IntType> struct choose_hton<IntType, __ORDER_BIG_ENDIAN__> {
     inline static IntType hton(const IntType& value) { return value; }
 };

 template <typename IntType> inline IntType hton(const IntType& value) {
     return choose_hton<IntType, __BYTE_ORDER__>::hton(value);
 }

 template <typename IntType> inline IntType ntoh(const IntType& value) {
     // same operation and hton
     return choose_hton<IntType, __BYTE_ORDER__>::hton(value);
 }

 bool KeymasterEnforcement::AuthTokenMatches(const AuthorizationSet& auth_set,
                                             const HardwareAuthToken& auth_token,
                                             const uint64_t user_secure_id,
                                             const int auth_type_index, const int auth_timeout_index,
                                             const uint64_t op_handle,
                                             bool is_begin_operation) const {
     assert(auth_type_index < static_cast<int>(auth_set.size()));
     assert(auth_timeout_index < static_cast<int>(auth_set.size()));

     if (!ValidateTokenSignature(auth_token)) {
         ALOGE("Auth token signature invalid");
         return false;
     }

     if (auth_timeout_index == -1 && op_handle && op_handle != auth_token.challenge) {
         ALOGE("Auth token has the challenge %" PRIu64 ", need %" PRIu64, auth_token.challenge,
               op_handle);
         return false;
     }

     if (user_secure_id != auth_token.userId && user_secure_id != auth_token.authenticatorId) {
         ALOGI("Auth token SIDs %" PRIu64 " and %" PRIu64 " do not match key SID %" PRIu64,
               auth_token.userId, auth_token.authenticatorId, user_secure_id);
         return false;
     }

     if (auth_type_index < 0 || auth_type_index > static_cast<int>(auth_set.size())) {
         ALOGE("Auth required but no auth type found");
         return false;
     }

     assert(auth_set[auth_type_index].tag == TAG_USER_AUTH_TYPE);
     auto key_auth_type_mask = authorizationValue(TAG_USER_AUTH_TYPE, auth_set[auth_type_index]);
     if (!key_auth_type_mask.isOk()) return false;

     if ((uint32_t(key_auth_type_mask.value()) & auth_token.authenticatorType) == 0) {
         ALOGE("Key requires match of auth type mask 0%uo, but token contained 0%uo",
               key_auth_type_mask.value(), auth_token.authenticatorType);
         return false;
     }

     if (auth_timeout_index != -1 && is_begin_operation) {
         assert(auth_set[auth_timeout_index].tag == TAG_AUTH_TIMEOUT);
         auto auth_token_timeout =
             authorizationValue(TAG_AUTH_TIMEOUT, auth_set[auth_timeout_index]);
         if (!auth_token_timeout.isOk()) return false;

         if (auth_token_timed_out(auth_token, auth_token_timeout.value())) {
             ALOGE("Auth token has timed out");
             return false;
         }
     }

     // Survived the whole gauntlet.  We have authentage!
     return true;
 }

 bool AccessTimeMap::LastKeyAccessTime(km_id_t keyid, uint32_t* last_access_time) const {
     std::lock_guard<std::mutex> lock(list_lock_);
     for (auto& entry : last_access_list_)
         if (entry.keyid == keyid) {
             *last_access_time = entry.access_time;
             return true;
         }
     return false;
 }

 bool AccessTimeMap::UpdateKeyAccessTime(km_id_t keyid, uint32_t current_time, uint32_t timeout) {
     std::lock_guard<std::mutex> lock(list_lock_);
     for (auto iter = last_access_list_.begin(); iter != last_access_list_.end();) {
         if (iter->keyid == keyid) {
             iter->access_time = current_time;
             return true;
         }

         // Expire entry if possible.
         assert(current_time >= iter->access_time);
         if (current_time - iter->access_time >= iter->timeout)
             iter = last_access_list_.erase(iter);
         else
             ++iter;
     }

     if (last_access_list_.size() >= max_size_) return false;

     AccessTime new_entry;
     new_entry.keyid = keyid;
     new_entry.access_time = current_time;
     new_entry.timeout = timeout;
     last_access_list_.push_front(new_entry);
     return true;
 }

 bool AccessCountMap::KeyAccessCount(km_id_t keyid, uint32_t* count) const {
     std::lock_guard<std::mutex> lock(list_lock_);
     for (auto& entry : access_count_list_)
         if (entry.keyid == keyid) {
             *count = entry.access_count;
             return true;
         }
     return false;
 }

 bool AccessCountMap::IncrementKeyAccessCount(km_id_t keyid) {
     std::lock_guard<std::mutex> lock(list_lock_);
     for (auto& entry : access_count_list_)
         if (entry.keyid == keyid) {
             // Note that the 'if' below will always be true because KM_TAG_MAX_USES_PER_BOOT is a
             // uint32_t, and as soon as entry.access_count reaches the specified maximum value
             // operation requests will be rejected and access_count won't be incremented any more.
             // And, besides, UINT64_MAX is huge.  But we ensure that it doesn't wrap anyway, out of
             // an abundance of caution.
             if (entry.access_count < UINT64_MAX) ++entry.access_count;
             return true;
         }

     if (access_count_list_.size() >= max_size_) return false;

     AccessCount new_entry;
     new_entry.keyid = keyid;
     new_entry.access_count = 1;
     access_count_list_.push_front(new_entry);
     return true;
 }
 }; /* namespace keystore */
	/*
	* Copyright (C) 2014 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.
	*/

	#define LOG_TAG "keystore"

	#include "keymaster_enforcement.h"

	#include <assert.h>
	#include <inttypes.h>
	#include <limits.h>
	#include <string.h>

	#include <openssl/evp.h>

	#include <hardware/hw_auth_token.h>
	#include <log/log.h>

	#include <list>

	#include <keystore/keystore_hidl_support.h>

	namespace keystore {

	bool is_public_key_algorithm(const AuthorizationSet& auth_set) {
	auto algorithm = auth_set.GetTagValue(TAG_ALGORITHM);
	return algorithm.isOk() &&
	(algorithm.value() == Algorithm::RSA \|\| algorithm.value() == Algorithm::EC);
	}

	static ErrorCode authorized_purpose(const KeyPurpose purpose, const AuthorizationSet& auth_set) {
	switch (purpose) {
	case KeyPurpose::VERIFY:
	case KeyPurpose::ENCRYPT:
	case KeyPurpose::SIGN:
	case KeyPurpose::DECRYPT:
	if (auth_set.Contains(TAG_PURPOSE, purpose)) return ErrorCode::OK;
	return ErrorCode::INCOMPATIBLE_PURPOSE;

	default:
	return ErrorCode::UNSUPPORTED_PURPOSE;
	}
	}

	inline bool is_origination_purpose(KeyPurpose purpose) {
	return purpose == KeyPurpose::ENCRYPT \|\| purpose == KeyPurpose::SIGN;
	}

	inline bool is_usage_purpose(KeyPurpose purpose) {
	return purpose == KeyPurpose::DECRYPT \|\| purpose == KeyPurpose::VERIFY;
	}

	KeymasterEnforcement::KeymasterEnforcement(uint32_t max_access_time_map_size,
	uint32_t max_access_count_map_size)
	: access_time_map_(max_access_time_map_size), access_count_map_(max_access_count_map_size) {}

	KeymasterEnforcement::~KeymasterEnforcement() {
	}

	ErrorCode KeymasterEnforcement::AuthorizeOperation(const KeyPurpose purpose, const km_id_t keyid,
	const AuthorizationSet& auth_set,
	const AuthorizationSet& operation_params,
	const HardwareAuthToken& auth_token,
	uint64_t op_handle, bool is_begin_operation) {
	if (is_public_key_algorithm(auth_set)) {
	switch (purpose) {
	case KeyPurpose::ENCRYPT:
	case KeyPurpose::VERIFY:
	/* Public key operations are always authorized. */
	return ErrorCode::OK;

	case KeyPurpose::DECRYPT:
	case KeyPurpose::SIGN:
	break;

	case KeyPurpose::WRAP_KEY:
	return ErrorCode::INCOMPATIBLE_PURPOSE;
	};
	};

	if (is_begin_operation)
	return AuthorizeBegin(purpose, keyid, auth_set, operation_params, auth_token);
	else
	return AuthorizeUpdateOrFinish(auth_set, auth_token, op_handle);
	}

	// For update and finish the only thing to check is user authentication, and then only if it's not
	// timeout-based.
	ErrorCode KeymasterEnforcement::AuthorizeUpdateOrFinish(const AuthorizationSet& auth_set,
	const HardwareAuthToken& auth_token,
	uint64_t op_handle) {
	int auth_type_index = -1;
	for (size_t pos = 0; pos < auth_set.size(); ++pos) {
	switch (auth_set[pos].tag) {
	case Tag::NO_AUTH_REQUIRED:
	case Tag::AUTH_TIMEOUT:
	// If no auth is required or if auth is timeout-based, we have nothing to check.
	return ErrorCode::OK;

	case Tag::USER_AUTH_TYPE:
	auth_type_index = pos;
	break;

	default:
	break;
	}
	}

	// Note that at this point we should be able to assume that authentication is required, because
	// authentication is required if KM_TAG_NO_AUTH_REQUIRED is absent. However, there are legacy
	// keys which have no authentication-related tags, so we assume that absence is equivalent to
	// presence of KM_TAG_NO_AUTH_REQUIRED.
	//
	// So, if we found KM_TAG_USER_AUTH_TYPE or if we find KM_TAG_USER_SECURE_ID then authentication
	// is required. If we find neither, then we assume authentication is not required and return
	// success.
	bool authentication_required = (auth_type_index != -1);
	for (auto& param : auth_set) {
	auto user_secure_id = authorizationValue(TAG_USER_SECURE_ID, param);
	if (user_secure_id.isOk()) {
	authentication_required = true;
	int auth_timeout_index = -1;
	if (auth_token.mac.size() &&
	AuthTokenMatches(auth_set, auth_token, user_secure_id.value(), auth_type_index,
	auth_timeout_index, op_handle, false /* is_begin_operation */))
	return ErrorCode::OK;
	}
	}

	if (authentication_required) return ErrorCode::KEY_USER_NOT_AUTHENTICATED;

	return ErrorCode::OK;
	}

	ErrorCode KeymasterEnforcement::AuthorizeBegin(const KeyPurpose purpose, const km_id_t keyid,
	const AuthorizationSet& auth_set,
	const AuthorizationSet& operation_params,
	NullOr<const HardwareAuthToken&> auth_token) {
	// Find some entries that may be needed to handle KM_TAG_USER_SECURE_ID
	int auth_timeout_index = -1;
	int auth_type_index = -1;
	int no_auth_required_index = -1;
	for (size_t pos = 0; pos < auth_set.size(); ++pos) {
	switch (auth_set[pos].tag) {
	case Tag::AUTH_TIMEOUT:
	auth_timeout_index = pos;
	break;
	case Tag::USER_AUTH_TYPE:
	auth_type_index = pos;
	break;
	case Tag::NO_AUTH_REQUIRED:
	no_auth_required_index = pos;
	break;
	default:
	break;
	}
	}

	ErrorCode error = authorized_purpose(purpose, auth_set);
	if (error != ErrorCode::OK) return error;

	// If successful, and if key has a min time between ops, this will be set to the time limit
	uint32_t min_ops_timeout = UINT32_MAX;

	bool update_access_count = false;
	bool caller_nonce_authorized_by_key = false;
	bool authentication_required = false;
	bool auth_token_matched = false;
	bool unlocked_device_required = false;
	int32_t user_id = -1;

	for (auto& param : auth_set) {

	// KM_TAG_PADDING_OLD and KM_TAG_DIGEST_OLD aren't actually members of the enum, so we can't
	// switch on them. There's nothing to validate for them, though, so just ignore them.
	if (int32_t(param.tag) == KM_TAG_PADDING_OLD \|\| int32_t(param.tag) == KM_TAG_DIGEST_OLD)
	continue;

	switch (param.tag) {

	case Tag::ACTIVE_DATETIME: {
	auto date = authorizationValue(TAG_ACTIVE_DATETIME, param);
	if (date.isOk() && !activation_date_valid(date.value()))
	return ErrorCode::KEY_NOT_YET_VALID;
	break;
	}
	case Tag::ORIGINATION_EXPIRE_DATETIME: {
	auto date = authorizationValue(TAG_ORIGINATION_EXPIRE_DATETIME, param);
	if (is_origination_purpose(purpose) && date.isOk() &&
	expiration_date_passed(date.value()))
	return ErrorCode::KEY_EXPIRED;
	break;
	}
	case Tag::USAGE_EXPIRE_DATETIME: {
	auto date = authorizationValue(TAG_USAGE_EXPIRE_DATETIME, param);
	if (is_usage_purpose(purpose) && date.isOk() && expiration_date_passed(date.value()))
	return ErrorCode::KEY_EXPIRED;
	break;
	}
	case Tag::MIN_SECONDS_BETWEEN_OPS: {
	auto min_ops_timeout = authorizationValue(TAG_MIN_SECONDS_BETWEEN_OPS, param);
	if (min_ops_timeout.isOk() && !MinTimeBetweenOpsPassed(min_ops_timeout.value(), keyid))
	return ErrorCode::KEY_RATE_LIMIT_EXCEEDED;
	break;
	}
	case Tag::MAX_USES_PER_BOOT: {
	auto max_users = authorizationValue(TAG_MAX_USES_PER_BOOT, param);
	update_access_count = true;
	if (max_users.isOk() && !MaxUsesPerBootNotExceeded(keyid, max_users.value()))
	return ErrorCode::KEY_MAX_OPS_EXCEEDED;
	break;
	}
	case Tag::USER_SECURE_ID:
	if (no_auth_required_index != -1) {
	// Key has both KM_TAG_USER_SECURE_ID and KM_TAG_NO_AUTH_REQUIRED
	return ErrorCode::INVALID_KEY_BLOB;
	}

	if (auth_timeout_index != -1) {
	auto secure_id = authorizationValue(TAG_USER_SECURE_ID, param);
	authentication_required = true;
	if (secure_id.isOk() && auth_token.isOk() &&
	AuthTokenMatches(auth_set, auth_token.value(), secure_id.value(),
	auth_type_index, auth_timeout_index, 0 /* op_handle */,
	true /* is_begin_operation */))
	auth_token_matched = true;
	}
	break;

	case Tag::USER_ID:
	user_id = authorizationValue(TAG_USER_ID, param).value();
	break;

	case Tag::CALLER_NONCE:
	caller_nonce_authorized_by_key = true;
	break;

	case Tag::UNLOCKED_DEVICE_REQUIRED:
	unlocked_device_required = true;
	break;

	/* Tags should never be in key auths. */
	case Tag::INVALID:
	case Tag::ROOT_OF_TRUST:
	case Tag::APPLICATION_DATA:
	case Tag::ATTESTATION_CHALLENGE:
	case Tag::ATTESTATION_APPLICATION_ID:
	case Tag::ATTESTATION_ID_BRAND:
	case Tag::ATTESTATION_ID_DEVICE:
	case Tag::ATTESTATION_ID_PRODUCT:
	case Tag::ATTESTATION_ID_SERIAL:
	case Tag::ATTESTATION_ID_IMEI:
	case Tag::ATTESTATION_ID_MEID:
	case Tag::ATTESTATION_ID_MANUFACTURER:
	case Tag::ATTESTATION_ID_MODEL:
	return ErrorCode::INVALID_KEY_BLOB;

	/* Tags used for cryptographic parameters in keygen. Nothing to enforce. */
	case Tag::PURPOSE:
	case Tag::ALGORITHM:
	case Tag::KEY_SIZE:
	case Tag::BLOCK_MODE:
	case Tag::DIGEST:
	case Tag::MAC_LENGTH:
	case Tag::PADDING:
	case Tag::NONCE:
	case Tag::MIN_MAC_LENGTH:
	case Tag::EC_CURVE:

	/* Tags not used for operations. */
	case Tag::BLOB_USAGE_REQUIREMENTS:

	/* Algorithm specific parameters not used for access control. */
	case Tag::RSA_PUBLIC_EXPONENT:

	/* Informational tags. */
	case Tag::CREATION_DATETIME:
	case Tag::ORIGIN:
	case Tag::ROLLBACK_RESISTANCE:

	/* Tags handled when KM_TAG_USER_SECURE_ID is handled */
	case Tag::NO_AUTH_REQUIRED:
	case Tag::USER_AUTH_TYPE:
	case Tag::AUTH_TIMEOUT:

	/* Tag to provide data to operations. */
	case Tag::ASSOCIATED_DATA:

	/* Tags that are implicitly verified by secure side */
	case Tag::APPLICATION_ID:
	case Tag::BOOT_PATCHLEVEL:
	case Tag::OS_PATCHLEVEL:
	case Tag::OS_VERSION:
	case Tag::TRUSTED_USER_PRESENCE_REQUIRED:
	case Tag::VENDOR_PATCHLEVEL:

	/* TODO(swillden): Handle these */
	case Tag::INCLUDE_UNIQUE_ID:
	case Tag::UNIQUE_ID:
	case Tag::RESET_SINCE_ID_ROTATION:
	case Tag::ALLOW_WHILE_ON_BODY:
	case Tag::HARDWARE_TYPE:
	case Tag::TRUSTED_CONFIRMATION_REQUIRED:
	case Tag::CONFIRMATION_TOKEN:
	break;

	case Tag::BOOTLOADER_ONLY:
	return ErrorCode::INVALID_KEY_BLOB;
	}
	}

	if (unlocked_device_required && is_device_locked(user_id)) {
	switch (purpose) {
	case KeyPurpose::ENCRYPT:
	case KeyPurpose::VERIFY:
	/* These are okay */
	break;
	case KeyPurpose::DECRYPT:
	case KeyPurpose::SIGN:
	case KeyPurpose::WRAP_KEY:
	return ErrorCode::DEVICE_LOCKED;
	};
	}

	if (authentication_required && !auth_token_matched) {
	ALOGE("Auth required but no matching auth token found");
	return ErrorCode::KEY_USER_NOT_AUTHENTICATED;
	}

	if (!caller_nonce_authorized_by_key && is_origination_purpose(purpose) &&
	operation_params.Contains(Tag::NONCE))
	return ErrorCode::CALLER_NONCE_PROHIBITED;

	if (min_ops_timeout != UINT32_MAX) {
	if (!access_time_map_.UpdateKeyAccessTime(keyid, get_current_time(), min_ops_timeout)) {
	ALOGE("Rate-limited keys table full. Entries will time out.");
	return ErrorCode::TOO_MANY_OPERATIONS;
	}
	}

	if (update_access_count) {
	if (!access_count_map_.IncrementKeyAccessCount(keyid)) {
	ALOGE("Usage count-limited keys table full, until reboot.");
	return ErrorCode::TOO_MANY_OPERATIONS;
	}
	}

	return ErrorCode::OK;
	}

	class EvpMdCtx {
	public:
	EvpMdCtx() { EVP_MD_CTX_init(&ctx_); }
	~EvpMdCtx() { EVP_MD_CTX_cleanup(&ctx_); }

	EVP_MD_CTX* get() { return &ctx_; }

	private:
	EVP_MD_CTX ctx_;
	};

	/* static */
	std::optional<km_id_t> KeymasterEnforcement::CreateKeyId(const hidl_vec<uint8_t>& key_blob) {
	EvpMdCtx ctx;
	km_id_t keyid;

	uint8_t hash[EVP_MAX_MD_SIZE];
	unsigned int hash_len;
	if (EVP_DigestInit_ex(ctx.get(), EVP_sha256(), nullptr /* ENGINE */) &&
	EVP_DigestUpdate(ctx.get(), &key_blob[0], key_blob.size()) &&
	EVP_DigestFinal_ex(ctx.get(), hash, &hash_len)) {
	assert(hash_len >= sizeof(keyid));
	memcpy(&keyid, hash, sizeof(keyid));
	return keyid;
	}

	return {};
	}

	bool KeymasterEnforcement::MinTimeBetweenOpsPassed(uint32_t min_time_between, const km_id_t keyid) {
	uint32_t last_access_time;
	if (!access_time_map_.LastKeyAccessTime(keyid, &last_access_time)) return true;
	return min_time_between <= static_cast<int64_t>(get_current_time()) - last_access_time;
	}

	bool KeymasterEnforcement::MaxUsesPerBootNotExceeded(const km_id_t keyid, uint32_t max_uses) {
	uint32_t key_access_count;
	if (!access_count_map_.KeyAccessCount(keyid, &key_access_count)) return true;
	return key_access_count < max_uses;
	}

	template <typename IntType, uint32_t byteOrder> struct choose_hton;

	template <typename IntType> struct choose_hton<IntType, __ORDER_LITTLE_ENDIAN__> {
	inline static IntType hton(const IntType& value) {
	IntType result = 0;
	const unsigned char* inbytes = reinterpret_cast<const unsigned char*>(&value);
	unsigned char* outbytes = reinterpret_cast<unsigned char*>(&result);
	for (int i = sizeof(IntType) - 1; i >= 0; --i) {
	*(outbytes++) = inbytes[i];
	}
	return result;
	}
	};

	template <typename IntType> struct choose_hton<IntType, __ORDER_BIG_ENDIAN__> {
	inline static IntType hton(const IntType& value) { return value; }
	};

	template <typename IntType> inline IntType hton(const IntType& value) {
	return choose_hton<IntType, __BYTE_ORDER__>::hton(value);
	}

	template <typename IntType> inline IntType ntoh(const IntType& value) {
	// same operation and hton
	return choose_hton<IntType, __BYTE_ORDER__>::hton(value);
	}

	bool KeymasterEnforcement::AuthTokenMatches(const AuthorizationSet& auth_set,
	const HardwareAuthToken& auth_token,
	const uint64_t user_secure_id,
	const int auth_type_index, const int auth_timeout_index,
	const uint64_t op_handle,
	bool is_begin_operation) const {
	assert(auth_type_index < static_cast<int>(auth_set.size()));
	assert(auth_timeout_index < static_cast<int>(auth_set.size()));

	if (!ValidateTokenSignature(auth_token)) {
	ALOGE("Auth token signature invalid");
	return false;
	}

	if (auth_timeout_index == -1 && op_handle && op_handle != auth_token.challenge) {
	ALOGE("Auth token has the challenge %" PRIu64 ", need %" PRIu64, auth_token.challenge,
	op_handle);
	return false;
	}

	if (user_secure_id != auth_token.userId && user_secure_id != auth_token.authenticatorId) {
	ALOGI("Auth token SIDs %" PRIu64 " and %" PRIu64 " do not match key SID %" PRIu64,
	auth_token.userId, auth_token.authenticatorId, user_secure_id);
	return false;
	}

	if (auth_type_index < 0 \|\| auth_type_index > static_cast<int>(auth_set.size())) {
	ALOGE("Auth required but no auth type found");
	return false;
	}

	assert(auth_set[auth_type_index].tag == TAG_USER_AUTH_TYPE);
	auto key_auth_type_mask = authorizationValue(TAG_USER_AUTH_TYPE, auth_set[auth_type_index]);
	if (!key_auth_type_mask.isOk()) return false;

	if ((uint32_t(key_auth_type_mask.value()) & auth_token.authenticatorType) == 0) {
	ALOGE("Key requires match of auth type mask 0%uo, but token contained 0%uo",
	key_auth_type_mask.value(), auth_token.authenticatorType);
	return false;
	}

	if (auth_timeout_index != -1 && is_begin_operation) {
	assert(auth_set[auth_timeout_index].tag == TAG_AUTH_TIMEOUT);
	auto auth_token_timeout =
	authorizationValue(TAG_AUTH_TIMEOUT, auth_set[auth_timeout_index]);
	if (!auth_token_timeout.isOk()) return false;

	if (auth_token_timed_out(auth_token, auth_token_timeout.value())) {
	ALOGE("Auth token has timed out");
	return false;
	}
	}

	// Survived the whole gauntlet. We have authentage!
	return true;
	}

	bool AccessTimeMap::LastKeyAccessTime(km_id_t keyid, uint32_t* last_access_time) const {
	std::lock_guard<std::mutex> lock(list_lock_);
	for (auto& entry : last_access_list_)
	if (entry.keyid == keyid) {
	*last_access_time = entry.access_time;
	return true;
	}
	return false;
	}

	bool AccessTimeMap::UpdateKeyAccessTime(km_id_t keyid, uint32_t current_time, uint32_t timeout) {
	std::lock_guard<std::mutex> lock(list_lock_);
	for (auto iter = last_access_list_.begin(); iter != last_access_list_.end();) {
	if (iter->keyid == keyid) {
	iter->access_time = current_time;
	return true;
	}

	// Expire entry if possible.
	assert(current_time >= iter->access_time);
	if (current_time - iter->access_time >= iter->timeout)
	iter = last_access_list_.erase(iter);
	else
	++iter;
	}

	if (last_access_list_.size() >= max_size_) return false;

	AccessTime new_entry;
	new_entry.keyid = keyid;
	new_entry.access_time = current_time;
	new_entry.timeout = timeout;
	last_access_list_.push_front(new_entry);
	return true;
	}

	bool AccessCountMap::KeyAccessCount(km_id_t keyid, uint32_t* count) const {
	std::lock_guard<std::mutex> lock(list_lock_);
	for (auto& entry : access_count_list_)
	if (entry.keyid == keyid) {
	*count = entry.access_count;
	return true;
	}
	return false;
	}

	bool AccessCountMap::IncrementKeyAccessCount(km_id_t keyid) {
	std::lock_guard<std::mutex> lock(list_lock_);
	for (auto& entry : access_count_list_)
	if (entry.keyid == keyid) {
	// Note that the 'if' below will always be true because KM_TAG_MAX_USES_PER_BOOT is a
	// uint32_t, and as soon as entry.access_count reaches the specified maximum value
	// operation requests will be rejected and access_count won't be incremented any more.
	// And, besides, UINT64_MAX is huge. But we ensure that it doesn't wrap anyway, out of
	// an abundance of caution.
	if (entry.access_count < UINT64_MAX) ++entry.access_count;
	return true;
	}

	if (access_count_list_.size() >= max_size_) return false;

	AccessCount new_entry;
	new_entry.keyid = keyid;
	new_entry.access_count = 1;
	access_count_list_.push_front(new_entry);
	return true;
	}
	}; /* namespace keystore */