/* * 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 #include "mbedtls/platform.h" /****************************************************************/ /* 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 \emptydescription * \retval #PSA_ERROR_DATA_INVALID \emptydescription * \retval #PSA_ERROR_DATA_CORRUPT \emptydescription * \retval #PSA_ERROR_STORAGE_FAILURE \emptydescription * \retval #PSA_ERROR_DOES_NOT_EXIST \emptydescription */ 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 \emptydescription * \retval #PSA_ERROR_INSUFFICIENT_STORAGE \emptydescription * \retval #PSA_ERROR_ALREADY_EXISTS \emptydescription * \retval #PSA_ERROR_STORAGE_FAILURE \emptydescription * \retval #PSA_ERROR_DATA_INVALID \emptydescription */ 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 \emptydescription * \retval #PSA_ERROR_STORAGE_FAILURE \emptydescription * \retval #PSA_ERROR_DOES_NOT_EXIST \emptydescription * \retval #PSA_ERROR_DATA_CORRUPT \emptydescription */ 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_zeroize_and_free(storage_data, storage_data_length); return status; } void psa_free_persistent_key_data(uint8_t *key_data, size_t key_data_length) { mbedtls_zeroize_and_free(key_data, key_data_length); } 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_zeroize_and_free(loaded_data, storage_data_length); 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 */