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Factor the common idiom psa_wipe_key_slot into a function

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Many places in the code called psa_remove_key_data_from_memory (which
preserves metadata for the sake of failues in psa_import_key) followed
by clearing the slot data. Use an auxiliary function for this.
This commit is contained in:
Gilles Peskine 2018-12-03 11:58:46 +01:00
parent a426168cbf
commit f77ed1f20b
1 changed files with 19 additions and 10 deletions
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29
library/psa_crypto.c
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@ -637,6 +637,9 @@ exit:
}
#endif /* defined(MBEDTLS_ECP_C) */
/** Import key data into a slot. `slot->type` must have been set
* previously. This function assumes that the slot does not contain
* any key material yet. On failure, the slot content is unchanged. */
static psa_status_t psa_import_key_into_slot( key_slot_t *slot,
const uint8_t *data,
size_t data_length )
@ -840,6 +843,7 @@ static psa_status_t psa_get_key_from_slot( psa_key_slot_t key,
return( PSA_SUCCESS );
}
/** Wipe key data from a slot. Preserve metadata such as the policy. */
static psa_status_t psa_remove_key_data_from_memory( key_slot_t *slot )
{
if( slot->type == PSA_KEY_TYPE_NONE )
@ -876,6 +880,18 @@ static psa_status_t psa_remove_key_data_from_memory( key_slot_t *slot )
return( PSA_SUCCESS );
}
/** Completely wipe a slot in memory, including its policy.
* Persistent storage is not affected. */
static psa_status_t psa_wipe_key_slot( 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
* been wiped. Clear remaining metadata. We can call memset and not
* zeroize because the metadata is not particularly sensitive. */
memset( slot, 0, sizeof( *slot ) );
return( status );
}
/* A slot is available if nothing has been set in it: default lifetime
* and policy, no key type. */
static int psa_internal_is_slot_available( key_slot_t *slot )
@ -942,7 +958,6 @@ psa_status_t psa_internal_release_key_slot( psa_key_handle_t handle )
{
psa_key_slot_t key;
key_slot_t *slot;
psa_status_t status;
/* Don't call psa_get_key_slot() so as not to trigger its automatic
* loading of persistent key data. */
if( ( handle & PSA_KEY_HANDLE_ALLOCATED_FLAG ) == 0 )
@ -953,9 +968,7 @@ psa_status_t psa_internal_release_key_slot( psa_key_handle_t handle )
slot = &global_data.key_slots[key - 1];
if( ! slot->allocated )
return( PSA_ERROR_INVALID_HANDLE );
status = psa_remove_key_data_from_memory( slot );
memset( slot, 0, sizeof( *slot ) );
return( status );
return( psa_wipe_key_slot( slot ) );
}
psa_status_t psa_import_key( psa_key_slot_t key,
@ -1013,9 +1026,7 @@ psa_status_t psa_destroy_key( psa_key_slot_t key )
psa_destroy_persistent_key( slot->persistent_storage_id );
}
#endif /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */
status = psa_remove_key_data_from_memory( slot );
/* Zeroize the slot to wipe metadata such as policies. */
mbedtls_zeroize( slot, sizeof( *slot ) );
status = psa_wipe_key_slot( slot );
if( status != PSA_SUCCESS )
return( status );
return( storage_status );
@ -4565,9 +4576,7 @@ void mbedtls_psa_crypto_free( void )
for( key = 1; key <= PSA_KEY_SLOT_COUNT; key++ )
{
key_slot_t *slot = &global_data.key_slots[key - 1];
(void) psa_remove_key_data_from_memory( slot );
/* Zeroize the slot to wipe metadata such as policies. */
mbedtls_zeroize( slot, sizeof( *slot ) );
(void) psa_wipe_key_slot( slot );
}
}
if( global_data.rng_state != RNG_NOT_INITIALIZED )