mbedtls/library/psa_crypto_slot_management.c
Gilles Peskine b46bef2f76 Store the key size in the slot in memory
There is now a field for the key size in the key slot in memory. Use
it.

This makes psa_get_key_attributes() marginally faster at the expense
of memory that is available anyway in the current memory layout (16
bits for the size, 16 bits for flags). That's not the goal, though:
the goal is to simplify the code, in particular to make it more
uniform between transparent keys (whose size can be recomputed) and
keys in secure elements (whose size cannot be recomputed).

For keys in a secure element, the bit size is now saved by serializing
the type psa_key_bits_t (which is an alias for uint16_t) rather than
size_t.
2019-07-31 14:16:50 +02:00

302 lines
9 KiB
C

/*
* 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"
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
#include "psa_crypto_se.h"
#endif
#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( ! psa_key_slot_get_flags( slot, PSA_KEY_SLOT_FLAG_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;
}
psa_status_t psa_internal_allocate_key_slot( psa_key_handle_t *handle,
psa_key_slot_t **p_slot )
{
if( ! global_data.key_slots_initialized )
return( PSA_ERROR_BAD_STATE );
for( *handle = PSA_KEY_SLOT_COUNT; *handle != 0; --( *handle ) )
{
*p_slot = &global_data.key_slots[*handle - 1];
if( ! psa_key_slot_get_flags( *p_slot, PSA_KEY_SLOT_FLAG_ALLOCATED ) )
{
psa_key_slot_set_bits_in_flags( *p_slot,
PSA_KEY_SLOT_FLAG_ALLOCATED );
return( PSA_SUCCESS );
}
}
*p_slot = NULL;
return( PSA_ERROR_INSUFFICIENT_MEMORY );
}
#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
static psa_status_t psa_load_persistent_key_into_slot( psa_key_slot_t *slot )
{
psa_status_t status = PSA_SUCCESS;
uint8_t *key_data = NULL;
size_t key_data_length = 0;
status = psa_load_persistent_key( &slot->attr,
&key_data, &key_data_length );
if( status != PSA_SUCCESS )
goto exit;
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
if( psa_key_lifetime_is_external( slot->attr.lifetime ) )
{
psa_se_key_data_storage_t *data;
if( key_data_length != sizeof( *data ) )
{
status = PSA_ERROR_STORAGE_FAILURE;
goto exit;
}
data = (psa_se_key_data_storage_t *) key_data;
memcpy( &slot->data.se.slot_number, &data->slot_number,
sizeof( slot->data.se.slot_number ) );
memcpy( &slot->attr.bits, &data->bits,
sizeof( slot->attr.bits ) );
}
else
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
{
status = psa_import_key_into_slot( 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.
* \param vendor_ok Nonzero to allow key ids in the vendor range.
* 0 to allow only key ids in the application range.
*
* \return 1 if \p file_id is acceptable, otherwise 0.
*/
static int psa_is_key_id_valid( psa_key_file_id_t file_id,
int vendor_ok )
{
psa_app_key_id_t key_id = PSA_KEY_FILE_GET_KEY_ID( file_id );
if( PSA_KEY_ID_USER_MIN <= key_id && key_id <= PSA_KEY_ID_USER_MAX )
return( 1 );
else if( vendor_ok &&
PSA_KEY_ID_VENDOR_MIN <= key_id &&
key_id <= PSA_KEY_ID_VENDOR_MAX )
return( 1 );
else
return( 0 );
}
#endif /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */
psa_status_t psa_validate_persistent_key_parameters(
psa_key_lifetime_t lifetime,
psa_key_file_id_t id,
psa_se_drv_table_entry_t **p_drv,
int creating )
{
if( p_drv != NULL )
*p_drv = NULL;
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
if( psa_key_lifetime_is_external( lifetime ) )
{
*p_drv = psa_get_se_driver_entry( lifetime );
if( *p_drv == NULL )
return( PSA_ERROR_INVALID_ARGUMENT );
}
else
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
if( lifetime != PSA_KEY_LIFETIME_PERSISTENT )
return( PSA_ERROR_INVALID_ARGUMENT );
#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
if( ! psa_is_key_id_valid( id, ! creating ) )
return( PSA_ERROR_INVALID_ARGUMENT );
return( PSA_SUCCESS );
#else /* MBEDTLS_PSA_CRYPTO_STORAGE_C */
(void) id;
(void) creating;
return( PSA_ERROR_NOT_SUPPORTED );
#endif /* !MBEDTLS_PSA_CRYPTO_STORAGE_C */
}
psa_status_t psa_open_key( psa_key_file_id_t id, psa_key_handle_t *handle )
{
#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
psa_status_t status;
psa_key_slot_t *slot;
*handle = 0;
status = psa_validate_persistent_key_parameters(
PSA_KEY_LIFETIME_PERSISTENT, id, NULL, 0 );
if( status != PSA_SUCCESS )
return( status );
status = psa_internal_allocate_key_slot( handle, &slot );
if( status != PSA_SUCCESS )
return( status );
slot->attr.lifetime = PSA_KEY_LIFETIME_PERSISTENT;
slot->attr.id = id;
status = psa_load_persistent_key_into_slot( slot );
if( status != PSA_SUCCESS )
{
psa_wipe_key_slot( slot );
*handle = 0;
}
return( status );
#else /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */
(void) id;
*handle = 0;
return( PSA_ERROR_NOT_SUPPORTED );
#endif /* !defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */
}
psa_status_t psa_close_key( psa_key_handle_t handle )
{
psa_status_t status;
psa_key_slot_t *slot;
status = psa_get_key_slot( handle, &slot );
if( status != PSA_SUCCESS )
return( status );
return( psa_wipe_key_slot( slot ) );
}
void mbedtls_psa_get_stats( mbedtls_psa_stats_t *stats )
{
psa_key_handle_t key;
memset( stats, 0, sizeof( *stats ) );
for( key = 1; key <= PSA_KEY_SLOT_COUNT; key++ )
{
psa_key_slot_t *slot = &global_data.key_slots[key - 1];
if( slot->attr.type == PSA_KEY_TYPE_NONE )
{
if( psa_key_slot_get_flags( slot, PSA_KEY_SLOT_FLAG_ALLOCATED ) )
++stats->half_filled_slots;
else
++stats->empty_slots;
continue;
}
if( slot->attr.lifetime == PSA_KEY_LIFETIME_VOLATILE )
++stats->volatile_slots;
else if( slot->attr.lifetime == PSA_KEY_LIFETIME_PERSISTENT )
{
++stats->persistent_slots;
if( slot->attr.id > stats->max_open_internal_key_id )
stats->max_open_internal_key_id = slot->attr.id;
}
else
{
++stats->external_slots;
if( slot->attr.id > stats->max_open_external_key_id )
stats->max_open_external_key_id = slot->attr.id;
}
}
}
#endif /* MBEDTLS_PSA_CRYPTO_C */