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Move the key slot array to the slot management module

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Move the key slot array and its initialization and wiping to the slot
management module.

Also move the lowest-level key slot access function psa_get_key_slot
and the auxiliary function for slot allocation
psa_internal_allocate_key_slot to the slot management module.
This commit is contained in:
Gilles Peskine 2018-12-10 16:29:04 +01:00
parent 408319be3a
commit 66fb126e87
4 changed files with 105 additions and 71 deletions
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76
library/psa_crypto.c
View file

@ -130,10 +130,8 @@ typedef struct
void (* entropy_free )( mbedtls_entropy_context *ctx );
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
psa_key_slot_t key_slots[PSA_KEY_SLOT_COUNT];
unsigned initialized : 1;
unsigned rng_state : 2;
unsigned key_slots_initialized : 1;
} psa_global_data_t;
static psa_global_data_t global_data;
@ -715,31 +713,6 @@ exit:
}
#endif /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */
/* 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. */
static psa_status_t psa_get_key_slot( psa_key_handle_t handle,
psa_key_slot_t **p_slot )
{
psa_key_slot_t *slot = NULL;
GUARD_MODULE_INITIALIZED;
/* 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 );
}
/* Retrieve an empty key slot (slot with no key data, but possibly
* with some metadata such as a policy). */
static psa_status_t psa_get_empty_key_slot( psa_key_handle_t handle,
@ -834,7 +807,7 @@ static psa_status_t psa_remove_key_data_from_memory( psa_key_slot_t *slot )
/** Completely wipe a slot in memory, including its policy.
* Persistent storage is not affected. */
static psa_status_t psa_wipe_key_slot( psa_key_slot_t *slot )
psa_status_t psa_wipe_key_slot( psa_key_slot_t *slot )
{
psa_status_t status = psa_remove_key_data_from_memory( slot );
/* At this point, key material and other type-specific content has
@ -844,20 +817,6 @@ static psa_status_t psa_wipe_key_slot( psa_key_slot_t *slot )
return( status );
}
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 );
}
psa_status_t psa_internal_make_key_persistent( psa_key_handle_t handle,
psa_key_id_t id )
{
@ -4473,15 +4432,7 @@ psa_status_t mbedtls_psa_crypto_configure_entropy_sources(
void mbedtls_psa_crypto_free( void )
{
if( global_data.key_slots_initialized )
{
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 );
}
}
psa_wipe_all_key_slots( );
if( global_data.rng_state != RNG_NOT_INITIALIZED )
{
mbedtls_ctr_drbg_free( &global_data.ctr_drbg );
@ -4495,7 +4446,7 @@ void mbedtls_psa_crypto_free( void )
psa_status_t psa_crypto_init( void )
{
int ret;
psa_status_t status;
const unsigned char drbg_seed[] = "PSA";
/* Double initialization is explicitly allowed. */
@ -4513,25 +4464,26 @@ psa_status_t psa_crypto_init( void )
global_data.entropy_init( &global_data.entropy );
mbedtls_ctr_drbg_init( &global_data.ctr_drbg );
global_data.rng_state = RNG_INITIALIZED;
ret = mbedtls_ctr_drbg_seed( &global_data.ctr_drbg,
mbedtls_entropy_func,
&global_data.entropy,
drbg_seed, sizeof( drbg_seed ) - 1 );
if( ret != 0 )
status = mbedtls_to_psa_error(
mbedtls_ctr_drbg_seed( &global_data.ctr_drbg,
mbedtls_entropy_func,
&global_data.entropy,
drbg_seed, sizeof( drbg_seed ) - 1 ) );
if( status != PSA_SUCCESS )
goto exit;
global_data.rng_state = RNG_SEEDED;
/* Initialize the key slots. Zero-initialization has made all key
* slots empty, so there is nothing to do. */
global_data.key_slots_initialized = 1;
status = psa_initialize_key_slots( );
if( status != PSA_SUCCESS )
goto exit;
/* All done. */
global_data.initialized = 1;
exit:
if( ret != 0 )
if( status != PSA_SUCCESS )
mbedtls_psa_crypto_free( );
return( mbedtls_to_psa_error( ret ) );
return( status );
}
#endif /* MBEDTLS_PSA_CRYPTO_C */

4
library/psa_crypto_core.h
View file

@ -59,4 +59,8 @@ typedef struct
} data;
} psa_key_slot_t;
/** Completely wipe a slot in memory, including its policy.
* Persistent storage is not affected. */
psa_status_t psa_wipe_key_slot( psa_key_slot_t *slot );
#endif /* PSA_CRYPTO_CORE_H */

76
library/psa_crypto_slot_management.c
View file

@ -29,6 +29,7 @@
#include "psa/crypto.h"
#include "psa_crypto_core.h"
#include "psa_crypto_slot_management.h"
#include "psa_crypto_storage.h"
@ -43,6 +44,81 @@
#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;
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.
*
* \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 );
}
psa_status_t psa_allocate_key( psa_key_type_t type,
size_t max_bits,
psa_key_handle_t *handle )

20
library/psa_crypto_slot_management.h
View file

@ -26,19 +26,21 @@
* The value is a compile-time constant for now, for simplicity. */
#define PSA_KEY_SLOT_COUNT 32
/** Access a key slot at the given handle. */
psa_status_t psa_get_key_slot( psa_key_handle_t handle,
psa_key_slot_t **p_slot );
/** Initialize the key slot structures. */
psa_status_t psa_initialize_key_slots( void );
/** Delete all data from key slots in memory. This does not affect persistent
* storage. */
void psa_wipe_all_key_slots( void );
/** \defgroup core_slot_management Internal functions exposed by the core
* @{
*/
/** Find a free key slot and mark it as in use.
*
* \param[out] handle On success, a slot number that is not in use.
*
* \retval #PSA_SUCCESS
* \retval #PSA_ERROR_INSUFFICIENT_MEMORY
*/
psa_status_t psa_internal_allocate_key_slot( psa_key_handle_t *handle );
/** Wipe an a key slot and mark it as available.
*
* This does not affect persistent storage.