/* * PSA persistent key storage */ /* * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 * * 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. */ #include "common.h" #if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) #include #include #include "psa/crypto.h" #include "psa_crypto_storage.h" #include "mbedtls/platform_util.h" #if defined(MBEDTLS_PSA_ITS_FILE_C) #include "psa_crypto_its.h" #else /* Native ITS implementation */ #include "psa/error.h" #include "psa/internal_trusted_storage.h" #endif #if defined(MBEDTLS_PLATFORM_C) #include "mbedtls/platform.h" #else #include #define mbedtls_calloc calloc #define mbedtls_free free #endif /****************************************************************/ /* Key storage */ /****************************************************************/ /* Determine a file name (ITS file identifier) for the given key identifier. * The file name must be distinct from any file that is used for a purpose * other than storing a key. Currently, the only such file is the random seed * file whose name is PSA_CRYPTO_ITS_RANDOM_SEED_UID and whose value is * 0xFFFFFF52. */ static psa_storage_uid_t psa_its_identifier_of_slot( mbedtls_svc_key_id_t key ) { #if defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER) /* Encode the owner in the upper 32 bits. This means that if * owner values are nonzero (as they are on a PSA platform), * no key file will ever have a value less than 0x100000000, so * the whole range 0..0xffffffff is available for non-key files. */ uint32_t unsigned_owner_id = MBEDTLS_SVC_KEY_ID_GET_OWNER_ID( key ); return( ( (uint64_t) unsigned_owner_id << 32 ) | MBEDTLS_SVC_KEY_ID_GET_KEY_ID( key ) ); #else /* Use the key id directly as a file name. * psa_is_key_id_valid() in psa_crypto_slot_management.c * is responsible for ensuring that key identifiers do not have a * value that is reserved for non-key files. */ return( key ); #endif } /** * \brief Load persistent data for the given key slot number. * * This function reads data from a storage backend and returns the data in a * buffer. * * \param key Persistent identifier of the key to be loaded. This * should be an occupied storage location. * \param[out] data Buffer where the data is to be written. * \param data_size Size of the \c data buffer in bytes. * * \retval #PSA_SUCCESS * \retval #PSA_ERROR_DATA_INVALID * \retval #PSA_ERROR_DATA_CORRUPT * \retval #PSA_ERROR_STORAGE_FAILURE * \retval #PSA_ERROR_DOES_NOT_EXIST */ static psa_status_t psa_crypto_storage_load( const mbedtls_svc_key_id_t key, uint8_t *data, size_t data_size ) { psa_status_t status; psa_storage_uid_t data_identifier = psa_its_identifier_of_slot( key ); struct psa_storage_info_t data_identifier_info; size_t data_length = 0; status = psa_its_get_info( data_identifier, &data_identifier_info ); if( status != PSA_SUCCESS ) return( status ); status = psa_its_get( data_identifier, 0, (uint32_t) data_size, data, &data_length ); if( data_size != data_length ) return( PSA_ERROR_DATA_INVALID ); return( status ); } int psa_is_key_present_in_storage( const mbedtls_svc_key_id_t key ) { psa_status_t ret; psa_storage_uid_t data_identifier = psa_its_identifier_of_slot( key ); struct psa_storage_info_t data_identifier_info; ret = psa_its_get_info( data_identifier, &data_identifier_info ); if( ret == PSA_ERROR_DOES_NOT_EXIST ) return( 0 ); return( 1 ); } /** * \brief Store persistent data for the given key slot number. * * This function stores the given data buffer to a persistent storage. * * \param key Persistent identifier of the key to be stored. This * should be an unoccupied storage location. * \param[in] data Buffer containing the data to be stored. * \param data_length The number of bytes * that make up the data. * * \retval #PSA_SUCCESS * \retval #PSA_ERROR_INSUFFICIENT_STORAGE * \retval #PSA_ERROR_ALREADY_EXISTS * \retval #PSA_ERROR_STORAGE_FAILURE * \retval #PSA_ERROR_DATA_INVALID */ static psa_status_t psa_crypto_storage_store( const mbedtls_svc_key_id_t key, const uint8_t *data, size_t data_length ) { psa_status_t status; psa_storage_uid_t data_identifier = psa_its_identifier_of_slot( key ); struct psa_storage_info_t data_identifier_info; if( psa_is_key_present_in_storage( key ) == 1 ) return( PSA_ERROR_ALREADY_EXISTS ); status = psa_its_set( data_identifier, (uint32_t) data_length, data, 0 ); if( status != PSA_SUCCESS ) { return( PSA_ERROR_DATA_INVALID ); } status = psa_its_get_info( data_identifier, &data_identifier_info ); if( status != PSA_SUCCESS ) { goto exit; } if( data_identifier_info.size != data_length ) { status = PSA_ERROR_DATA_INVALID; goto exit; } exit: if( status != PSA_SUCCESS ) { /* Remove the file in case we managed to create it but something * went wrong. It's ok if the file doesn't exist. If the file exists * but the removal fails, we're already reporting an error so there's * nothing else we can do. */ (void) psa_its_remove( data_identifier ); } return( status ); } psa_status_t psa_destroy_persistent_key( const mbedtls_svc_key_id_t key ) { psa_status_t ret; psa_storage_uid_t data_identifier = psa_its_identifier_of_slot( key ); struct psa_storage_info_t data_identifier_info; ret = psa_its_get_info( data_identifier, &data_identifier_info ); if( ret == PSA_ERROR_DOES_NOT_EXIST ) return( PSA_SUCCESS ); if( psa_its_remove( data_identifier ) != PSA_SUCCESS ) return( PSA_ERROR_DATA_INVALID ); ret = psa_its_get_info( data_identifier, &data_identifier_info ); if( ret != PSA_ERROR_DOES_NOT_EXIST ) return( PSA_ERROR_DATA_INVALID ); return( PSA_SUCCESS ); } /** * \brief Get data length for given key slot number. * * \param key Persistent identifier whose stored data length * is to be obtained. * \param[out] data_length The number of bytes that make up the data. * * \retval #PSA_SUCCESS * \retval #PSA_ERROR_STORAGE_FAILURE * \retval #PSA_ERROR_DOES_NOT_EXIST * \retval #PSA_ERROR_DATA_CORRUPT */ static psa_status_t psa_crypto_storage_get_data_length( const mbedtls_svc_key_id_t key, size_t *data_length ) { psa_status_t status; psa_storage_uid_t data_identifier = psa_its_identifier_of_slot( key ); struct psa_storage_info_t data_identifier_info; status = psa_its_get_info( data_identifier, &data_identifier_info ); if( status != PSA_SUCCESS ) return( status ); *data_length = (size_t) data_identifier_info.size; return( PSA_SUCCESS ); } /** * Persistent key storage magic header. */ #define PSA_KEY_STORAGE_MAGIC_HEADER "PSA\0KEY" #define PSA_KEY_STORAGE_MAGIC_HEADER_LENGTH ( sizeof( PSA_KEY_STORAGE_MAGIC_HEADER ) ) typedef struct { uint8_t magic[PSA_KEY_STORAGE_MAGIC_HEADER_LENGTH]; uint8_t version[4]; uint8_t lifetime[sizeof( psa_key_lifetime_t )]; uint8_t type[2]; uint8_t bits[2]; uint8_t policy[sizeof( psa_key_policy_t )]; uint8_t data_len[4]; uint8_t key_data[]; } psa_persistent_key_storage_format; void psa_format_key_data_for_storage( const uint8_t *data, const size_t data_length, const psa_core_key_attributes_t *attr, uint8_t *storage_data ) { psa_persistent_key_storage_format *storage_format = (psa_persistent_key_storage_format *) storage_data; memcpy( storage_format->magic, PSA_KEY_STORAGE_MAGIC_HEADER, PSA_KEY_STORAGE_MAGIC_HEADER_LENGTH ); MBEDTLS_PUT_UINT32_LE( 0, storage_format->version, 0 ); MBEDTLS_PUT_UINT32_LE( attr->lifetime, storage_format->lifetime, 0 ); MBEDTLS_PUT_UINT16_LE( (uint16_t) attr->type, storage_format->type, 0 ); MBEDTLS_PUT_UINT16_LE( (uint16_t) attr->bits, storage_format->bits, 0 ); MBEDTLS_PUT_UINT32_LE( attr->policy.usage, storage_format->policy, 0 ); MBEDTLS_PUT_UINT32_LE( attr->policy.alg, storage_format->policy, sizeof( uint32_t ) ); MBEDTLS_PUT_UINT32_LE( attr->policy.alg2, storage_format->policy, 2 * sizeof( uint32_t ) ); MBEDTLS_PUT_UINT32_LE( data_length, storage_format->data_len, 0 ); memcpy( storage_format->key_data, data, data_length ); } static psa_status_t check_magic_header( const uint8_t *data ) { if( memcmp( data, PSA_KEY_STORAGE_MAGIC_HEADER, PSA_KEY_STORAGE_MAGIC_HEADER_LENGTH ) != 0 ) return( PSA_ERROR_DATA_INVALID ); return( PSA_SUCCESS ); } psa_status_t psa_parse_key_data_from_storage( const uint8_t *storage_data, size_t storage_data_length, uint8_t **key_data, size_t *key_data_length, psa_core_key_attributes_t *attr ) { psa_status_t status; const psa_persistent_key_storage_format *storage_format = (const psa_persistent_key_storage_format *)storage_data; uint32_t version; if( storage_data_length < sizeof(*storage_format) ) return( PSA_ERROR_DATA_INVALID ); status = check_magic_header( storage_data ); if( status != PSA_SUCCESS ) return( status ); version = MBEDTLS_GET_UINT32_LE( storage_format->version, 0 ); if( version != 0 ) return( PSA_ERROR_DATA_INVALID ); *key_data_length = MBEDTLS_GET_UINT32_LE( storage_format->data_len, 0 ); if( *key_data_length > ( storage_data_length - sizeof(*storage_format) ) || *key_data_length > PSA_CRYPTO_MAX_STORAGE_SIZE ) return( PSA_ERROR_DATA_INVALID ); if( *key_data_length == 0 ) { *key_data = NULL; } else { *key_data = mbedtls_calloc( 1, *key_data_length ); if( *key_data == NULL ) return( PSA_ERROR_INSUFFICIENT_MEMORY ); memcpy( *key_data, storage_format->key_data, *key_data_length ); } attr->lifetime = MBEDTLS_GET_UINT32_LE( storage_format->lifetime, 0 ); attr->type = MBEDTLS_GET_UINT16_LE( storage_format->type, 0 ); attr->bits = MBEDTLS_GET_UINT16_LE( storage_format->bits, 0 ); attr->policy.usage = MBEDTLS_GET_UINT32_LE( storage_format->policy, 0 ); attr->policy.alg = MBEDTLS_GET_UINT32_LE( storage_format->policy, sizeof( uint32_t ) ); attr->policy.alg2 = MBEDTLS_GET_UINT32_LE( storage_format->policy, 2 * sizeof( uint32_t ) ); return( PSA_SUCCESS ); } psa_status_t psa_save_persistent_key( const psa_core_key_attributes_t *attr, const uint8_t *data, const size_t data_length ) { size_t storage_data_length; uint8_t *storage_data; psa_status_t status; /* All keys saved to persistent storage always have a key context */ if( data == NULL || data_length == 0 ) return( PSA_ERROR_INVALID_ARGUMENT ); if( data_length > PSA_CRYPTO_MAX_STORAGE_SIZE ) return( PSA_ERROR_INSUFFICIENT_STORAGE ); storage_data_length = data_length + sizeof( psa_persistent_key_storage_format ); storage_data = mbedtls_calloc( 1, storage_data_length ); if( storage_data == NULL ) return( PSA_ERROR_INSUFFICIENT_MEMORY ); psa_format_key_data_for_storage( data, data_length, attr, storage_data ); status = psa_crypto_storage_store( attr->id, storage_data, storage_data_length ); mbedtls_platform_zeroize( storage_data, storage_data_length ); mbedtls_free( storage_data ); return( status ); } void psa_free_persistent_key_data( uint8_t *key_data, size_t key_data_length ) { if( key_data != NULL ) { mbedtls_platform_zeroize( key_data, key_data_length ); } mbedtls_free( key_data ); } psa_status_t psa_load_persistent_key( psa_core_key_attributes_t *attr, uint8_t **data, size_t *data_length ) { psa_status_t status = PSA_SUCCESS; uint8_t *loaded_data; size_t storage_data_length = 0; mbedtls_svc_key_id_t key = attr->id; status = psa_crypto_storage_get_data_length( key, &storage_data_length ); if( status != PSA_SUCCESS ) return( status ); loaded_data = mbedtls_calloc( 1, storage_data_length ); if( loaded_data == NULL ) return( PSA_ERROR_INSUFFICIENT_MEMORY ); status = psa_crypto_storage_load( key, loaded_data, storage_data_length ); if( status != PSA_SUCCESS ) goto exit; status = psa_parse_key_data_from_storage( loaded_data, storage_data_length, data, data_length, attr ); /* All keys saved to persistent storage always have a key context */ if( status == PSA_SUCCESS && ( *data == NULL || *data_length == 0 ) ) status = PSA_ERROR_STORAGE_FAILURE; exit: mbedtls_platform_zeroize( loaded_data, storage_data_length ); mbedtls_free( loaded_data ); return( status ); } /****************************************************************/ /* Transactions */ /****************************************************************/ #if defined(PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS) psa_crypto_transaction_t psa_crypto_transaction; psa_status_t psa_crypto_save_transaction( void ) { struct psa_storage_info_t p_info; psa_status_t status; status = psa_its_get_info( PSA_CRYPTO_ITS_TRANSACTION_UID, &p_info ); if( status == PSA_SUCCESS ) { /* This shouldn't happen: we're trying to start a transaction while * there is still a transaction that hasn't been replayed. */ return( PSA_ERROR_CORRUPTION_DETECTED ); } else if( status != PSA_ERROR_DOES_NOT_EXIST ) return( status ); return( psa_its_set( PSA_CRYPTO_ITS_TRANSACTION_UID, sizeof( psa_crypto_transaction ), &psa_crypto_transaction, 0 ) ); } psa_status_t psa_crypto_load_transaction( void ) { psa_status_t status; size_t length; status = psa_its_get( PSA_CRYPTO_ITS_TRANSACTION_UID, 0, sizeof( psa_crypto_transaction ), &psa_crypto_transaction, &length ); if( status != PSA_SUCCESS ) return( status ); if( length != sizeof( psa_crypto_transaction ) ) return( PSA_ERROR_DATA_INVALID ); return( PSA_SUCCESS ); } psa_status_t psa_crypto_stop_transaction( void ) { psa_status_t status = psa_its_remove( PSA_CRYPTO_ITS_TRANSACTION_UID ); /* Whether or not updating the storage succeeded, the transaction is * finished now. It's too late to go back, so zero out the in-memory * data. */ memset( &psa_crypto_transaction, 0, sizeof( psa_crypto_transaction ) ); return( status ); } #endif /* PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS */ /****************************************************************/ /* Random generator state */ /****************************************************************/ #if defined(MBEDTLS_PSA_INJECT_ENTROPY) psa_status_t mbedtls_psa_storage_inject_entropy( const unsigned char *seed, size_t seed_size ) { psa_status_t status; struct psa_storage_info_t p_info; status = psa_its_get_info( PSA_CRYPTO_ITS_RANDOM_SEED_UID, &p_info ); if( PSA_ERROR_DOES_NOT_EXIST == status ) /* No seed exists */ { status = psa_its_set( PSA_CRYPTO_ITS_RANDOM_SEED_UID, seed_size, seed, 0 ); } else if( PSA_SUCCESS == status ) { /* You should not be here. Seed needs to be injected only once */ status = PSA_ERROR_NOT_PERMITTED; } return( status ); } #endif /* MBEDTLS_PSA_INJECT_ENTROPY */ /****************************************************************/ /* The end */ /****************************************************************/ #endif /* MBEDTLS_PSA_CRYPTO_STORAGE_C */