/*
* PSA crypto layer on top of Mbed TLS crypto
*/
/* Copyright (C) 2018, ARM Limited, All Rights Reserved
* 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.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_PSA_CRYPTO_C)
#include "psa_crypto_service_integration.h"
#include "psa/crypto.h"
#include "psa_crypto_core.h"
#include "psa_crypto_slot_management.h"
#include "psa_crypto_storage.h"
#include <stdlib.h>
#include <string.h>
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif
#define ARRAY_LENGTH( array ) ( sizeof( array ) / sizeof( *( array ) ) )
typedef struct
{
psa_key_slot_t key_slots[PSA_KEY_SLOT_COUNT];
unsigned key_slots_initialized : 1;
} psa_global_data_t;
static psa_global_data_t global_data;
/* Access a key slot at the given handle. The handle of a key slot is
* the index of the slot in the global slot array, plus one so that handles
* start at 1 and not 0. */
psa_status_t psa_get_key_slot( psa_key_handle_t handle,
psa_key_slot_t **p_slot )
{
psa_key_slot_t *slot = NULL;
if( ! global_data.key_slots_initialized )
return( PSA_ERROR_BAD_STATE );
/* 0 is not a valid handle under any circumstance. This
* implementation provides slots number 1 to N where N is the
* number of available slots. */
if( handle == 0 || handle > ARRAY_LENGTH( global_data.key_slots ) )
return( PSA_ERROR_INVALID_HANDLE );
slot = &global_data.key_slots[handle - 1];
/* If the slot hasn't been allocated, the handle is invalid. */
if( ! slot->allocated )
return( PSA_ERROR_INVALID_HANDLE );
*p_slot = slot;
return( PSA_SUCCESS );
}
psa_status_t psa_initialize_key_slots( void )
{
/* Nothing to do: program startup and psa_wipe_all_key_slots() both
* guarantee that the key slots are initialized to all-zero, which
* means that all the key slots are in a valid, empty state. */
global_data.key_slots_initialized = 1;
return( PSA_SUCCESS );
}
void psa_wipe_all_key_slots( void )
{
psa_key_handle_t key;
for( key = 1; key <= PSA_KEY_SLOT_COUNT; key++ )
{
psa_key_slot_t *slot = &global_data.key_slots[key - 1];
(void) psa_wipe_key_slot( slot );
}
global_data.key_slots_initialized = 0;
}
/** Find a free key slot and mark it as in use.
*
* \param[out] handle On success, a slot number that is not in use. This
* value can be used as a handle to the slot.
*
* \retval #PSA_SUCCESS
* \retval #PSA_ERROR_INSUFFICIENT_MEMORY
*/
static psa_status_t psa_internal_allocate_key_slot( psa_key_handle_t *handle )
{
for( *handle = PSA_KEY_SLOT_COUNT; *handle != 0; --( *handle ) )
{
psa_key_slot_t *slot = &global_data.key_slots[*handle - 1];
if( ! slot->allocated )
{
slot->allocated = 1;
return( PSA_SUCCESS );
}
}
return( PSA_ERROR_INSUFFICIENT_MEMORY );
}
/** Wipe a key slot and mark it as available.
*
* This does not affect persistent storage.
*
* \param handle The handle to the key slot to release.
*
* \retval #PSA_SUCCESS
* \retval #PSA_ERROR_INVALID_ARGUMENT
* \retval #PSA_ERROR_TAMPERING_DETECTED
*/
static psa_status_t psa_internal_release_key_slot( psa_key_handle_t handle )
{
psa_key_slot_t *slot;
psa_status_t status;
status = psa_get_key_slot( handle, &slot );
if( status != PSA_SUCCESS )
return( status );
return( psa_wipe_key_slot( slot ) );
}
psa_status_t psa_allocate_key( psa_key_handle_t *handle )
{
*handle = 0;
return( psa_internal_allocate_key_slot( handle ) );
}
#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
static psa_status_t psa_load_persistent_key_into_slot( psa_key_slot_t *p_slot )
{
psa_status_t status = PSA_SUCCESS;
uint8_t *key_data = NULL;
size_t key_data_length = 0;
status = psa_load_persistent_key( p_slot->persistent_storage_id,
&( p_slot )->type,
&( p_slot )->policy, &key_data,
&key_data_length );
if( status != PSA_SUCCESS )
goto exit;
status = psa_import_key_into_slot( p_slot,
key_data, key_data_length );
exit:
psa_free_persistent_key_data( key_data, key_data_length );
return( status );
}
/** Check whether a key identifier is acceptable.
*
* For backward compatibility, key identifiers that were valid in a
* past released version must remain valid, unless a migration path
* is provided.
*
* \param file_id The key identifier to check.
*
* \return 1 if \p file_id is acceptable, otherwise 0.
*/
static int psa_is_key_id_valid( psa_key_file_id_t file_id )
{
psa_app_key_id_t key_id = PSA_KEY_FILE_GET_KEY_ID( file_id );
/* Reject id=0 because by general library conventions, 0 is an invalid
* value wherever possible. */
if( key_id == 0 )
return( 0 );
/* Reject high values because the file names are reserved for the
* library's internal use. */
if( key_id > PSA_MAX_PERSISTENT_KEY_IDENTIFIER )
return( 0 );
return( 1 );
}
#endif /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */
/** Declare a slot as persistent and load it from storage.
*
* This function may only be called immediately after a successful call
* to psa_internal_allocate_key_slot().
*
* \param handle A handle to a key slot freshly allocated with
* psa_internal_allocate_key_slot().
*
* \retval #PSA_SUCCESS
* The slot content was loaded successfully.
* \retval #PSA_ERROR_DOES_NOT_EXIST
* There is no content for this slot in persistent storage.
* \retval #PSA_ERROR_INVALID_HANDLE
* \retval #PSA_ERROR_INVALID_ARGUMENT
* \p id is not acceptable.
* \retval #PSA_ERROR_INSUFFICIENT_MEMORY
* \retval #PSA_ERROR_STORAGE_FAILURE
*/
static psa_status_t psa_internal_make_key_persistent( psa_key_handle_t handle,
psa_key_file_id_t id )
{
#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
psa_key_slot_t *slot;
psa_status_t status;
if( ! psa_is_key_id_valid( id ) )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_get_key_slot( handle, &slot );
if( status != PSA_SUCCESS )
return( status );
slot->lifetime = PSA_KEY_LIFETIME_PERSISTENT;
slot->persistent_storage_id = id;
status = psa_load_persistent_key_into_slot( slot );
return( status );
#else /* MBEDTLS_PSA_CRYPTO_STORAGE_C */
(void) handle;
(void) id;
return( PSA_ERROR_NOT_SUPPORTED );
#endif /* !MBEDTLS_PSA_CRYPTO_STORAGE_C */
}
static psa_status_t persistent_key_setup( psa_key_lifetime_t lifetime,
psa_key_file_id_t id,
psa_key_handle_t *handle,
psa_status_t wanted_load_status )
{
psa_status_t status;
*handle = 0;
if( lifetime != PSA_KEY_LIFETIME_PERSISTENT )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_internal_allocate_key_slot( handle );
if( status != PSA_SUCCESS )
return( status );
status = psa_internal_make_key_persistent( *handle, id );
if( status != wanted_load_status )
{
psa_internal_release_key_slot( *handle );
*handle = 0;
}
return( status );
}
psa_status_t psa_open_key( psa_key_lifetime_t lifetime,
psa_key_file_id_t id,
psa_key_handle_t *handle )
{
return( persistent_key_setup( lifetime, id, handle, PSA_SUCCESS ) );
}
psa_status_t psa_create_key( psa_key_lifetime_t lifetime,
psa_key_file_id_t id,
psa_key_handle_t *handle )
{
psa_status_t status;
status = persistent_key_setup( lifetime, id, handle,
PSA_ERROR_DOES_NOT_EXIST );
switch( status )
{
case PSA_SUCCESS: return( PSA_ERROR_ALREADY_EXISTS );
case PSA_ERROR_DOES_NOT_EXIST: return( PSA_SUCCESS );
default: return( status );
}
}
psa_status_t psa_close_key( psa_key_handle_t handle )
{
return( psa_internal_release_key_slot( handle ) );
}
#endif /* MBEDTLS_PSA_CRYPTO_C */