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SE keys: ensure that functions that lack support properly error out

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Introduce a new function psa_get_transparent_key which returns
NOT_SUPPORTED if the key is in a secure element. Use this function in
functions that don't support keys in a secure element.

After this commit, all functions that access a key slot directly via
psa_get_key_slot or psa_get_key_from_slot rather than via
psa_get_transparent_key have at least enough support for secure
elements not to crash or otherwise cause undefined behavior. Lesser
bad behavior such as wrong results or resource leakage is still
possible in error cases.
This commit is contained in:
Gilles Peskine 2019-07-24 13:30:31 +02:00
parent 573bbc1b4e
commit 28f8f3068f
1 changed files with 46 additions and 13 deletions
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59
library/psa_crypto.c
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@ -871,6 +871,39 @@ static psa_status_t psa_get_key_from_slot( psa_key_handle_t handle,
return( PSA_SUCCESS );
}
/** Retrieve a slot which must contain a transparent key.
*
* A transparent key is a key for which the key material is directly
* available, as opposed to a key in a secure element.
*
* This is a temporary function until secure element support is
* fully implemented.
*/
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
static psa_status_t psa_get_transparent_key( psa_key_handle_t handle,
psa_key_slot_t **p_slot,
psa_key_usage_t usage,
psa_algorithm_t alg )
{
psa_status_t status = psa_get_key_from_slot( handle, p_slot, usage, alg );
if( status != PSA_SUCCESS )
return( status );
/* Use a simple, cheap test to check whether the key is transparent.
* This check assumes that there are no persistent lifetimes other than
* PSA_KEY_LIFETIME_PERSISTENT. */
if( ( *p_slot )->lifetime > PSA_KEY_LIFETIME_PERSISTENT )
{
*p_slot = NULL;
return( PSA_ERROR_NOT_SUPPORTED );
}
return( PSA_SUCCESS );
}
#else /* MBEDTLS_PSA_CRYPTO_SE_C */
/* With no secure element support, all keys are transparent. */
#define psa_get_transparent_key( handle, p_slot, usage, alg ) \
psa_get_key_from_slot( handle, p_slot, usage, alg )
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
/** Wipe key data from a slot. Preserve metadata such as the policy. */
static psa_status_t psa_remove_key_data_from_memory( psa_key_slot_t *slot )
{
@ -1124,7 +1157,7 @@ psa_status_t psa_get_key_attributes( psa_key_handle_t handle,
psa_reset_key_attributes( attributes );
status = psa_get_key_slot( handle, &slot );
status = psa_get_transparent_key( handle, &slot, 0, 0 );
if( status != PSA_SUCCESS )
return( status );
@ -1704,7 +1737,7 @@ psa_status_t psa_copy_key( psa_key_handle_t source_handle,
psa_key_attributes_t actual_attributes = *specified_attributes;
psa_se_drv_table_entry_t *driver = NULL;
status = psa_get_key_from_slot( source_handle, &source_slot,
status = psa_get_transparent_key( source_handle, &source_slot,
PSA_KEY_USAGE_COPY, 0 );
if( status != PSA_SUCCESS )
goto exit;
@ -2485,7 +2518,7 @@ static psa_status_t psa_mac_setup( psa_mac_operation_t *operation,
if( is_sign )
operation->is_sign = 1;
status = psa_get_key_from_slot( handle, &slot, usage, alg );
status = psa_get_transparent_key( handle, &slot, usage, alg );
if( status != PSA_SUCCESS )
goto exit;
key_bits = psa_get_key_slot_bits( slot );
@ -3064,7 +3097,7 @@ psa_status_t psa_asymmetric_sign( psa_key_handle_t handle,
*signature_length = signature_size;
status = psa_get_key_from_slot( handle, &slot, PSA_KEY_USAGE_SIGN, alg );
status = psa_get_transparent_key( handle, &slot, PSA_KEY_USAGE_SIGN, alg );
if( status != PSA_SUCCESS )
goto exit;
if( ! PSA_KEY_TYPE_IS_KEY_PAIR( slot->type ) )
@ -3137,7 +3170,7 @@ psa_status_t psa_asymmetric_verify( psa_key_handle_t handle,
psa_key_slot_t *slot;
psa_status_t status;
status = psa_get_key_from_slot( handle, &slot, PSA_KEY_USAGE_VERIFY, alg );
status = psa_get_transparent_key( handle, &slot, PSA_KEY_USAGE_VERIFY, alg );
if( status != PSA_SUCCESS )
return( status );
@ -3207,7 +3240,7 @@ psa_status_t psa_asymmetric_encrypt( psa_key_handle_t handle,
if( ! PSA_ALG_IS_RSA_OAEP( alg ) && salt_length != 0 )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_get_key_from_slot( handle, &slot, PSA_KEY_USAGE_ENCRYPT, alg );
status = psa_get_transparent_key( handle, &slot, PSA_KEY_USAGE_ENCRYPT, alg );
if( status != PSA_SUCCESS )
return( status );
if( ! ( PSA_KEY_TYPE_IS_PUBLIC_KEY( slot->type ) ||
@ -3287,7 +3320,7 @@ psa_status_t psa_asymmetric_decrypt( psa_key_handle_t handle,
if( ! PSA_ALG_IS_RSA_OAEP( alg ) && salt_length != 0 )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_get_key_from_slot( handle, &slot, PSA_KEY_USAGE_DECRYPT, alg );
status = psa_get_transparent_key( handle, &slot, PSA_KEY_USAGE_DECRYPT, alg );
if( status != PSA_SUCCESS )
return( status );
if( ! PSA_KEY_TYPE_IS_KEY_PAIR( slot->type ) )
@ -3396,7 +3429,7 @@ static psa_status_t psa_cipher_setup( psa_cipher_operation_t *operation,
if( status != PSA_SUCCESS )
return( status );
status = psa_get_key_from_slot( handle, &slot, usage, alg);
status = psa_get_transparent_key( handle, &slot, usage, alg);
if( status != PSA_SUCCESS )
goto exit;
key_bits = psa_get_key_slot_bits( slot );
@ -3733,7 +3766,7 @@ static psa_status_t psa_aead_setup( aead_operation_t *operation,
size_t key_bits;
mbedtls_cipher_id_t cipher_id;
status = psa_get_key_from_slot( handle, &operation->slot, usage, alg );
status = psa_get_transparent_key( handle, &operation->slot, usage, alg );
if( status != PSA_SUCCESS )
return( status );
@ -4908,7 +4941,7 @@ psa_status_t psa_key_derivation( psa_key_derivation_operation_t *operation,
if( ! PSA_ALG_IS_KEY_DERIVATION( alg ) )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_get_key_from_slot( handle, &slot, PSA_KEY_USAGE_DERIVE, alg );
status = psa_get_transparent_key( handle, &slot, PSA_KEY_USAGE_DERIVE, alg );
if( status != PSA_SUCCESS )
return( status );
@ -5282,7 +5315,7 @@ psa_status_t psa_key_derivation_input_key(
{
psa_key_slot_t *slot;
psa_status_t status;
status = psa_get_key_from_slot( handle, &slot,
status = psa_get_transparent_key( handle, &slot,
PSA_KEY_USAGE_DERIVE,
operation->alg );
if( status != PSA_SUCCESS )
@ -5431,7 +5464,7 @@ psa_status_t psa_key_derivation_key_agreement( psa_key_derivation_operation_t *o
psa_status_t status;
if( ! PSA_ALG_IS_KEY_AGREEMENT( operation->alg ) )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_get_key_from_slot( private_key, &slot,
status = psa_get_transparent_key( private_key, &slot,
PSA_KEY_USAGE_DERIVE, operation->alg );
if( status != PSA_SUCCESS )
return( status );
@ -5459,7 +5492,7 @@ psa_status_t psa_raw_key_agreement( psa_algorithm_t alg,
status = PSA_ERROR_INVALID_ARGUMENT;
goto exit;
}
status = psa_get_key_from_slot( private_key, &slot,
status = psa_get_transparent_key( private_key, &slot,
PSA_KEY_USAGE_DERIVE, alg );
if( status != PSA_SUCCESS )
goto exit;