/** * \file psa_crypto_storage.h * * \brief PSA cryptography module: Mbed TLS key storage */ /* * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later */ #ifndef PSA_CRYPTO_STORAGE_H #define PSA_CRYPTO_STORAGE_H #ifdef __cplusplus extern "C" { #endif #include "psa/crypto.h" #include "psa/crypto_se_driver.h" #include <stdint.h> #include <string.h> /* Limit the maximum key size in storage. This should have no effect * since the key size is limited in memory. */ #define PSA_CRYPTO_MAX_STORAGE_SIZE … /* Sanity check: a file size must fit in 32 bits. Allow a generous * 64kB of metadata. */ #if PSA_CRYPTO_MAX_STORAGE_SIZE > 0xffff0000 #error "PSA_CRYPTO_MAX_STORAGE_SIZE > 0xffff0000" #endif /** The maximum permitted persistent slot number. * * In Mbed Crypto 0.1.0b: * - Using the file backend, all key ids are ok except 0. * - Using the ITS backend, all key ids are ok except 0xFFFFFF52 * (#PSA_CRYPTO_ITS_RANDOM_SEED_UID) for which the file contains the * device's random seed (if this feature is enabled). * - Only key ids from 1 to #MBEDTLS_PSA_KEY_SLOT_COUNT are actually used. * * Since we need to preserve the random seed, avoid using that key slot. * Reserve a whole range of key slots just in case something else comes up. * * This limitation will probably become moot when we implement client * separation for key storage. */ #define PSA_MAX_PERSISTENT_KEY_IDENTIFIER … /** * \brief Checks if persistent data is stored for the given key slot number * * This function checks if any key data or metadata exists for the key slot in * the persistent storage. * * \param key Persistent identifier to check. * * \retval 0 * No persistent data present for slot number * \retval 1 * Persistent data present for slot number */ int psa_is_key_present_in_storage(const mbedtls_svc_key_id_t key); /** * \brief Format key data and metadata and save to a location for given key * slot. * * This function formats the key data and metadata and saves it to a * persistent storage backend. The storage location corresponding to the * key slot must be empty, otherwise this function will fail. This function * should be called after loading the key into an internal slot to ensure the * persistent key is not saved into a storage location corresponding to an * already occupied non-persistent key, as well as ensuring the key data is * validated. * * Note: This function will only succeed for key buffers which are not * empty. If passed a NULL pointer or zero-length, the function will fail * with #PSA_ERROR_INVALID_ARGUMENT. * * \param[in] attr The attributes of the key to save. * The key identifier field in the attributes * determines the key's location. * \param[in] data Buffer containing the key data. * \param data_length The number of bytes that make up the key data. * * \retval #PSA_SUCCESS \emptydescription * \retval #PSA_ERROR_INVALID_ARGUMENT \emptydescription * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription * \retval #PSA_ERROR_INSUFFICIENT_STORAGE \emptydescription * \retval #PSA_ERROR_STORAGE_FAILURE \emptydescription * \retval #PSA_ERROR_ALREADY_EXISTS \emptydescription * \retval #PSA_ERROR_DATA_INVALID \emptydescription * \retval #PSA_ERROR_DATA_CORRUPT \emptydescription */ psa_status_t psa_save_persistent_key(const psa_key_attributes_t *attr, const uint8_t *data, const size_t data_length); /** * \brief Parses key data and metadata and load persistent key for given * key slot number. * * This function reads from a storage backend, parses the key data and * metadata and writes them to the appropriate output parameters. * * Note: This function allocates a buffer and returns a pointer to it through * the data parameter. On successful return, the pointer is guaranteed to be * valid and the buffer contains at least one byte of data. * psa_free_persistent_key_data() must be called on the data buffer * afterwards to zeroize and free this buffer. * * \param[in,out] attr On input, the key identifier field identifies * the key to load. Other fields are ignored. * On success, the attribute structure contains * the key metadata that was loaded from storage. * \param[out] data Pointer to an allocated key data buffer on return. * \param[out] data_length The number of bytes that make up the key data. * * \retval #PSA_SUCCESS \emptydescription * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription * \retval #PSA_ERROR_DATA_INVALID \emptydescription * \retval #PSA_ERROR_DATA_CORRUPT \emptydescription * \retval #PSA_ERROR_DOES_NOT_EXIST \emptydescription */ psa_status_t psa_load_persistent_key(psa_key_attributes_t *attr, uint8_t **data, size_t *data_length); /** * \brief Remove persistent data for the given key slot number. * * \param key Persistent identifier of the key to remove * from persistent storage. * * \retval #PSA_SUCCESS * The key was successfully removed, * or the key did not exist. * \retval #PSA_ERROR_DATA_INVALID \emptydescription */ psa_status_t psa_destroy_persistent_key(const mbedtls_svc_key_id_t key); /** * \brief Free the temporary buffer allocated by psa_load_persistent_key(). * * This function must be called at some point after psa_load_persistent_key() * to zeroize and free the memory allocated to the buffer in that function. * * \param key_data Buffer for the key data. * \param key_data_length Size of the key data buffer. * */ void psa_free_persistent_key_data(uint8_t *key_data, size_t key_data_length); /** * \brief Formats key data and metadata for persistent storage * * \param[in] data Buffer containing the key data. * \param data_length Length of the key data buffer. * \param[in] attr The core attributes of the key. * \param[out] storage_data Output buffer for the formatted data. * */ void psa_format_key_data_for_storage(const uint8_t *data, const size_t data_length, const psa_key_attributes_t *attr, uint8_t *storage_data); /** * \brief Parses persistent storage data into key data and metadata * * \param[in] storage_data Buffer for the storage data. * \param storage_data_length Length of the storage data buffer * \param[out] key_data On output, pointer to a newly allocated buffer * containing the key data. This must be freed * using psa_free_persistent_key_data() * \param[out] key_data_length Length of the key data buffer * \param[out] attr On success, the attribute structure is filled * with the loaded key metadata. * * \retval #PSA_SUCCESS \emptydescription * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription * \retval #PSA_ERROR_DATA_INVALID \emptydescription */ 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_key_attributes_t *attr); #if defined(MBEDTLS_PSA_CRYPTO_SE_C) /** This symbol is defined if transaction support is required. */ #define PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS … #endif #if defined(PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS) /** The type of transaction that is in progress. */ /* This is an integer type rather than an enum for two reasons: to support * unknown values when loading a transaction file, and to ensure that the * type has a known size. */ typedef uint16_t psa_crypto_transaction_type_t; /** No transaction is in progress. * * This has the value 0, so zero-initialization sets a transaction's type to * this value. */ #define PSA_CRYPTO_TRANSACTION_NONE … /** A key creation transaction. * * This is only used for keys in an external cryptoprocessor (secure element). * Keys in RAM or in internal storage are created atomically in storage * (simple file creation), so they do not need a transaction mechanism. */ #define PSA_CRYPTO_TRANSACTION_CREATE_KEY … /** A key destruction transaction. * * This is only used for keys in an external cryptoprocessor (secure element). * Keys in RAM or in internal storage are destroyed atomically in storage * (simple file deletion), so they do not need a transaction mechanism. */ #define PSA_CRYPTO_TRANSACTION_DESTROY_KEY … /** Transaction data. * * This type is designed to be serialized by writing the memory representation * and reading it back on the same device. * * \note The transaction mechanism is not thread-safe. There can only be one * single active transaction at a time. * The transaction object is #psa_crypto_transaction. * * \note If an API call starts a transaction, it must complete this transaction * before returning to the application. * * The lifetime of a transaction is the following (note that only one * transaction may be active at a time): * * -# Call psa_crypto_prepare_transaction() to initialize the transaction * object in memory and declare the type of transaction that is starting. * -# Fill in the type-specific fields of #psa_crypto_transaction. * -# Call psa_crypto_save_transaction() to start the transaction. This * saves the transaction data to internal storage. * -# Perform the work of the transaction by modifying files, contacting * external entities, or whatever needs doing. Note that the transaction * may be interrupted by a power failure, so you need to have a way * recover from interruptions either by undoing what has been done * so far or by resuming where you left off. * -# If there are intermediate stages in the transaction, update * the fields of #psa_crypto_transaction and call * psa_crypto_save_transaction() again when each stage is reached. * -# When the transaction is over, call psa_crypto_stop_transaction() to * remove the transaction data in storage and in memory. * * If the system crashes while a transaction is in progress, psa_crypto_init() * calls psa_crypto_load_transaction() and takes care of completing or * rewinding the transaction. This is done in psa_crypto_recover_transaction() * in psa_crypto.c. If you add a new type of transaction, be * sure to add code for it in psa_crypto_recover_transaction(). */ typedef union { /* Each element of this union must have the following properties * to facilitate serialization and deserialization: * * - The element is a struct. * - The first field of the struct is `psa_crypto_transaction_type_t type`. * - Elements of the struct are arranged such a way that there is * no padding. */ struct psa_crypto_transaction_unknown_s { psa_crypto_transaction_type_t type; uint16_t unused1; uint32_t unused2; uint64_t unused3; uint64_t unused4; } unknown; /* ::type is #PSA_CRYPTO_TRANSACTION_CREATE_KEY or * #PSA_CRYPTO_TRANSACTION_DESTROY_KEY. */ struct psa_crypto_transaction_key_s { psa_crypto_transaction_type_t type; uint16_t unused1; psa_key_lifetime_t lifetime; psa_key_slot_number_t slot; mbedtls_svc_key_id_t id; } key; } psa_crypto_transaction_t; /** The single active transaction. */ extern psa_crypto_transaction_t psa_crypto_transaction; /** Prepare for a transaction. * * There must not be an ongoing transaction. * * \param type The type of transaction to start. */ static inline void psa_crypto_prepare_transaction( psa_crypto_transaction_type_t type) { psa_crypto_transaction.unknown.type = type; } /** Save the transaction data to storage. * * You may call this function multiple times during a transaction to * atomically update the transaction state. * * \retval #PSA_SUCCESS \emptydescription * \retval #PSA_ERROR_DATA_CORRUPT \emptydescription * \retval #PSA_ERROR_INSUFFICIENT_STORAGE \emptydescription * \retval #PSA_ERROR_STORAGE_FAILURE \emptydescription */ psa_status_t psa_crypto_save_transaction(void); /** Load the transaction data from storage, if any. * * This function is meant to be called from psa_crypto_init() to recover * in case a transaction was interrupted by a system crash. * * \retval #PSA_SUCCESS * The data about the ongoing transaction has been loaded to * #psa_crypto_transaction. * \retval #PSA_ERROR_DOES_NOT_EXIST * There is no ongoing transaction. * \retval #PSA_ERROR_STORAGE_FAILURE \emptydescription * \retval #PSA_ERROR_DATA_INVALID \emptydescription * \retval #PSA_ERROR_DATA_CORRUPT \emptydescription */ psa_status_t psa_crypto_load_transaction(void); /** Indicate that the current transaction is finished. * * Call this function at the very end of transaction processing. * This function does not "commit" or "abort" the transaction: the storage * subsystem has no concept of "commit" and "abort", just saving and * removing the transaction information in storage. * * This function erases the transaction data in storage (if any) and * resets the transaction data in memory. * * \retval #PSA_SUCCESS * There was transaction data in storage. * \retval #PSA_ERROR_DOES_NOT_EXIST * There was no transaction data in storage. * \retval #PSA_ERROR_STORAGE_FAILURE * It was impossible to determine whether there was transaction data * in storage, or the transaction data could not be erased. */ psa_status_t psa_crypto_stop_transaction(void); /** The ITS file identifier for the transaction data. * * 0xffffffNN = special file; 0x74 = 't' for transaction. */ #define PSA_CRYPTO_ITS_TRANSACTION_UID … #endif /* PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS */ #if defined(MBEDTLS_PSA_INJECT_ENTROPY) /** Backend side of mbedtls_psa_inject_entropy(). * * This function stores the supplied data into the entropy seed file. * * \retval #PSA_SUCCESS * Success * \retval #PSA_ERROR_STORAGE_FAILURE \emptydescription * \retval #PSA_ERROR_INSUFFICIENT_STORAGE \emptydescription * \retval #PSA_ERROR_NOT_PERMITTED * The entropy seed file already exists. */ psa_status_t mbedtls_psa_storage_inject_entropy(const unsigned char *seed, size_t seed_size); #endif /* MBEDTLS_PSA_INJECT_ENTROPY */ #ifdef __cplusplus } #endif #endif /* PSA_CRYPTO_STORAGE_H */
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