| /* |
| * PSA crypto support for secure element drivers |
| */ |
| /* |
| * 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_SE_C) |
| |
| #include <assert.h> |
| #include <stdint.h> |
| #include <string.h> |
| |
| #include "psa/crypto_se_driver.h" |
| |
| #include "psa_crypto_se.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" |
| |
| |
| |
| /****************************************************************/ |
| /* Driver lookup */ |
| /****************************************************************/ |
| |
| /* This structure is identical to psa_drv_se_context_t declared in |
| * `crypto_se_driver.h`, except that some parts are writable here |
| * (non-const, or pointer to non-const). */ |
| typedef struct |
| { |
| void *persistent_data; |
| size_t persistent_data_size; |
| uintptr_t transient_data; |
| } psa_drv_se_internal_context_t; |
| |
| struct psa_se_drv_table_entry_s |
| { |
| psa_key_location_t location; |
| const psa_drv_se_t *methods; |
| union |
| { |
| psa_drv_se_internal_context_t internal; |
| psa_drv_se_context_t context; |
| } u; |
| }; |
| |
| static psa_se_drv_table_entry_t driver_table[PSA_MAX_SE_DRIVERS]; |
| |
| psa_se_drv_table_entry_t *psa_get_se_driver_entry( |
| psa_key_lifetime_t lifetime ) |
| { |
| size_t i; |
| psa_key_location_t location = PSA_KEY_LIFETIME_GET_LOCATION( lifetime ); |
| /* In the driver table, location=0 means an entry that isn't used. |
| * No driver has a location of 0 because it's a reserved value |
| * (which designates transparent keys). Make sure we never return |
| * a driver entry for location 0. */ |
| if( location == 0 ) |
| return( NULL ); |
| for( i = 0; i < PSA_MAX_SE_DRIVERS; i++ ) |
| { |
| if( driver_table[i].location == location ) |
| return( &driver_table[i] ); |
| } |
| return( NULL ); |
| } |
| |
| const psa_drv_se_t *psa_get_se_driver_methods( |
| const psa_se_drv_table_entry_t *driver ) |
| { |
| return( driver->methods ); |
| } |
| |
| psa_drv_se_context_t *psa_get_se_driver_context( |
| psa_se_drv_table_entry_t *driver ) |
| { |
| return( &driver->u.context ); |
| } |
| |
| int psa_get_se_driver( psa_key_lifetime_t lifetime, |
| const psa_drv_se_t **p_methods, |
| psa_drv_se_context_t **p_drv_context) |
| { |
| psa_se_drv_table_entry_t *driver = psa_get_se_driver_entry( lifetime ); |
| if( p_methods != NULL ) |
| *p_methods = ( driver ? driver->methods : NULL ); |
| if( p_drv_context != NULL ) |
| *p_drv_context = ( driver ? &driver->u.context : NULL ); |
| return( driver != NULL ); |
| } |
| |
| |
| |
| /****************************************************************/ |
| /* Persistent data management */ |
| /****************************************************************/ |
| |
| static psa_status_t psa_get_se_driver_its_file_uid( |
| const psa_se_drv_table_entry_t *driver, |
| psa_storage_uid_t *uid ) |
| { |
| if( driver->location > PSA_MAX_SE_LOCATION ) |
| return( PSA_ERROR_NOT_SUPPORTED ); |
| |
| #if SIZE_MAX > UINT32_MAX |
| /* ITS file sizes are limited to 32 bits. */ |
| if( driver->u.internal.persistent_data_size > UINT32_MAX ) |
| return( PSA_ERROR_NOT_SUPPORTED ); |
| #endif |
| |
| /* See the documentation of PSA_CRYPTO_SE_DRIVER_ITS_UID_BASE. */ |
| *uid = PSA_CRYPTO_SE_DRIVER_ITS_UID_BASE + driver->location; |
| return( PSA_SUCCESS ); |
| } |
| |
| psa_status_t psa_load_se_persistent_data( |
| const psa_se_drv_table_entry_t *driver ) |
| { |
| psa_status_t status; |
| psa_storage_uid_t uid; |
| size_t length; |
| |
| status = psa_get_se_driver_its_file_uid( driver, &uid ); |
| if( status != PSA_SUCCESS ) |
| return( status ); |
| |
| /* Read the amount of persistent data that the driver requests. |
| * If the data in storage is larger, it is truncated. If the data |
| * in storage is smaller, silently keep what is already at the end |
| * of the output buffer. */ |
| /* psa_get_se_driver_its_file_uid ensures that the size_t |
| * persistent_data_size is in range, but compilers don't know that, |
| * so cast to reassure them. */ |
| return( psa_its_get( uid, 0, |
| (uint32_t) driver->u.internal.persistent_data_size, |
| driver->u.internal.persistent_data, |
| &length ) ); |
| } |
| |
| psa_status_t psa_save_se_persistent_data( |
| const psa_se_drv_table_entry_t *driver ) |
| { |
| psa_status_t status; |
| psa_storage_uid_t uid; |
| |
| status = psa_get_se_driver_its_file_uid( driver, &uid ); |
| if( status != PSA_SUCCESS ) |
| return( status ); |
| |
| /* psa_get_se_driver_its_file_uid ensures that the size_t |
| * persistent_data_size is in range, but compilers don't know that, |
| * so cast to reassure them. */ |
| return( psa_its_set( uid, |
| (uint32_t) driver->u.internal.persistent_data_size, |
| driver->u.internal.persistent_data, |
| 0 ) ); |
| } |
| |
| psa_status_t psa_destroy_se_persistent_data( psa_key_location_t location ) |
| { |
| psa_storage_uid_t uid; |
| if( location > PSA_MAX_SE_LOCATION ) |
| return( PSA_ERROR_NOT_SUPPORTED ); |
| uid = PSA_CRYPTO_SE_DRIVER_ITS_UID_BASE + location; |
| return( psa_its_remove( uid ) ); |
| } |
| |
| psa_status_t psa_find_se_slot_for_key( |
| const psa_key_attributes_t *attributes, |
| psa_key_creation_method_t method, |
| psa_se_drv_table_entry_t *driver, |
| psa_key_slot_number_t *slot_number ) |
| { |
| psa_status_t status; |
| psa_key_location_t key_location = |
| PSA_KEY_LIFETIME_GET_LOCATION( psa_get_key_lifetime( attributes ) ); |
| |
| /* If the location is wrong, it's a bug in the library. */ |
| if( driver->location != key_location ) |
| return( PSA_ERROR_CORRUPTION_DETECTED ); |
| |
| /* If the driver doesn't support key creation in any way, give up now. */ |
| if( driver->methods->key_management == NULL ) |
| return( PSA_ERROR_NOT_SUPPORTED ); |
| |
| if( psa_get_key_slot_number( attributes, slot_number ) == PSA_SUCCESS ) |
| { |
| /* The application wants to use a specific slot. Allow it if |
| * the driver supports it. On a system with isolation, |
| * the crypto service must check that the application is |
| * permitted to request this slot. */ |
| psa_drv_se_validate_slot_number_t p_validate_slot_number = |
| driver->methods->key_management->p_validate_slot_number; |
| if( p_validate_slot_number == NULL ) |
| return( PSA_ERROR_NOT_SUPPORTED ); |
| status = p_validate_slot_number( &driver->u.context, |
| driver->u.internal.persistent_data, |
| attributes, method, |
| *slot_number ); |
| } |
| else if( method == PSA_KEY_CREATION_REGISTER ) |
| { |
| /* The application didn't specify a slot number. This doesn't |
| * make sense when registering a slot. */ |
| return( PSA_ERROR_INVALID_ARGUMENT ); |
| } |
| else |
| { |
| /* The application didn't tell us which slot to use. Let the driver |
| * choose. This is the normal case. */ |
| psa_drv_se_allocate_key_t p_allocate = |
| driver->methods->key_management->p_allocate; |
| if( p_allocate == NULL ) |
| return( PSA_ERROR_NOT_SUPPORTED ); |
| status = p_allocate( &driver->u.context, |
| driver->u.internal.persistent_data, |
| attributes, method, |
| slot_number ); |
| } |
| return( status ); |
| } |
| |
| psa_status_t psa_destroy_se_key( psa_se_drv_table_entry_t *driver, |
| psa_key_slot_number_t slot_number ) |
| { |
| psa_status_t status; |
| psa_status_t storage_status; |
| /* Normally a missing method would mean that the action is not |
| * supported. But psa_destroy_key() is not supposed to return |
| * PSA_ERROR_NOT_SUPPORTED: if you can create a key, you should |
| * be able to destroy it. The only use case for a driver that |
| * does not have a way to destroy keys at all is if the keys are |
| * locked in a read-only state: we can use the keys but not |
| * destroy them. Hence, if the driver doesn't support destroying |
| * keys, it's really a lack of permission. */ |
| if( driver->methods->key_management == NULL || |
| driver->methods->key_management->p_destroy == NULL ) |
| return( PSA_ERROR_NOT_PERMITTED ); |
| status = driver->methods->key_management->p_destroy( |
| &driver->u.context, |
| driver->u.internal.persistent_data, |
| slot_number ); |
| storage_status = psa_save_se_persistent_data( driver ); |
| return( status == PSA_SUCCESS ? storage_status : status ); |
| } |
| |
| psa_status_t psa_init_all_se_drivers( void ) |
| { |
| size_t i; |
| for( i = 0; i < PSA_MAX_SE_DRIVERS; i++ ) |
| { |
| psa_se_drv_table_entry_t *driver = &driver_table[i]; |
| if( driver->location == 0 ) |
| continue; /* skipping unused entry */ |
| const psa_drv_se_t *methods = psa_get_se_driver_methods( driver ); |
| if( methods->p_init != NULL ) |
| { |
| psa_status_t status = methods->p_init( |
| &driver->u.context, |
| driver->u.internal.persistent_data, |
| driver->location ); |
| if( status != PSA_SUCCESS ) |
| return( status ); |
| status = psa_save_se_persistent_data( driver ); |
| if( status != PSA_SUCCESS ) |
| return( status ); |
| } |
| } |
| return( PSA_SUCCESS ); |
| } |
| |
| |
| |
| /****************************************************************/ |
| /* Driver registration */ |
| /****************************************************************/ |
| |
| psa_status_t psa_register_se_driver( |
| psa_key_location_t location, |
| const psa_drv_se_t *methods) |
| { |
| size_t i; |
| psa_status_t status; |
| |
| if( methods->hal_version != PSA_DRV_SE_HAL_VERSION ) |
| return( PSA_ERROR_NOT_SUPPORTED ); |
| /* Driver table entries are 0-initialized. 0 is not a valid driver |
| * location because it means a transparent key. */ |
| #if defined(static_assert) |
| static_assert( PSA_KEY_LOCATION_LOCAL_STORAGE == 0, |
| "Secure element support requires 0 to mean a local key" ); |
| #endif |
| if( location == PSA_KEY_LOCATION_LOCAL_STORAGE ) |
| return( PSA_ERROR_INVALID_ARGUMENT ); |
| if( location > PSA_MAX_SE_LOCATION ) |
| return( PSA_ERROR_NOT_SUPPORTED ); |
| |
| for( i = 0; i < PSA_MAX_SE_DRIVERS; i++ ) |
| { |
| if( driver_table[i].location == 0 ) |
| break; |
| /* Check that location isn't already in use up to the first free |
| * entry. Since entries are created in order and never deleted, |
| * there can't be a used entry after the first free entry. */ |
| if( driver_table[i].location == location ) |
| return( PSA_ERROR_ALREADY_EXISTS ); |
| } |
| if( i == PSA_MAX_SE_DRIVERS ) |
| return( PSA_ERROR_INSUFFICIENT_MEMORY ); |
| |
| driver_table[i].location = location; |
| driver_table[i].methods = methods; |
| driver_table[i].u.internal.persistent_data_size = |
| methods->persistent_data_size; |
| |
| if( methods->persistent_data_size != 0 ) |
| { |
| driver_table[i].u.internal.persistent_data = |
| mbedtls_calloc( 1, methods->persistent_data_size ); |
| if( driver_table[i].u.internal.persistent_data == NULL ) |
| { |
| status = PSA_ERROR_INSUFFICIENT_MEMORY; |
| goto error; |
| } |
| /* Load the driver's persistent data. On first use, the persistent |
| * data does not exist in storage, and is initialized to |
| * all-bits-zero by the calloc call just above. */ |
| status = psa_load_se_persistent_data( &driver_table[i] ); |
| if( status != PSA_SUCCESS && status != PSA_ERROR_DOES_NOT_EXIST ) |
| goto error; |
| } |
| |
| return( PSA_SUCCESS ); |
| |
| error: |
| memset( &driver_table[i], 0, sizeof( driver_table[i] ) ); |
| return( status ); |
| } |
| |
| void psa_unregister_all_se_drivers( void ) |
| { |
| size_t i; |
| for( i = 0; i < PSA_MAX_SE_DRIVERS; i++ ) |
| { |
| if( driver_table[i].u.internal.persistent_data != NULL ) |
| mbedtls_free( driver_table[i].u.internal.persistent_data ); |
| } |
| memset( driver_table, 0, sizeof( driver_table ) ); |
| } |
| |
| |
| |
| /****************************************************************/ |
| /* The end */ |
| /****************************************************************/ |
| |
| #endif /* MBEDTLS_PSA_CRYPTO_SE_C */ |