/**
* \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 (PSA_BITS_TO_BYTES(PSA_MAX_KEY_BITS))
/* 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 PSA_KEY_ID_VENDOR_MAX
/**
* \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 1
#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 ((psa_crypto_transaction_type_t) 0x0000)
/** 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 ((psa_crypto_transaction_type_t) 0x0001)
/** 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 ((psa_crypto_transaction_type_t) 0x0002)
/** 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 ((psa_key_id_t) 0xffffff74)
#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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