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Merge pull request #257 from gilles-peskine-arm/psa-remove_zero_length_keys

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Forbid zero-length keys
This commit is contained in:
Gilles Peskine
2019-09-19 13:07:41 +02:00
committed by GitHub
parent fc95b847af 89cc74f447
commit a291413a1e
6 changed files with 171 additions and 53 deletions
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66
library/psa_crypto.c
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@ -451,13 +451,6 @@ static psa_status_t prepare_raw_data_slot( psa_key_type_t type,
switch( type )
{
case PSA_KEY_TYPE_RAW_DATA:
if( bits == 0 )
{
raw->bytes = 0;
raw->data = NULL;
return( PSA_SUCCESS );
}
break;
#if defined(MBEDTLS_MD_C)
case PSA_KEY_TYPE_HMAC:
#endif
@ -1281,6 +1274,12 @@ static psa_status_t psa_internal_export_key( const psa_key_slot_t *slot,
if( export_public_key && ! PSA_KEY_TYPE_IS_ASYMMETRIC( slot->attr.type ) )
return( PSA_ERROR_INVALID_ARGUMENT );
/* Reject a zero-length output buffer now, since this can never be a
* valid key representation. This way we know that data must be a valid
* pointer and we can do things like memset(data, ..., data_size). */
if( data_size == 0 )
return( PSA_ERROR_BUFFER_TOO_SMALL );
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
if( psa_get_se_driver( slot->attr.lifetime, &drv, &drv_context ) )
{
@ -1302,12 +1301,9 @@ static psa_status_t psa_internal_export_key( const psa_key_slot_t *slot,
{
if( slot->data.raw.bytes > data_size )
return( PSA_ERROR_BUFFER_TOO_SMALL );
if( data_size != 0 )
{
memcpy( data, slot->data.raw.data, slot->data.raw.bytes );
memset( data + slot->data.raw.bytes, 0,
data_size - slot->data.raw.bytes );
}
memcpy( data, slot->data.raw.data, slot->data.raw.bytes );
memset( data + slot->data.raw.bytes, 0,
data_size - slot->data.raw.bytes );
*data_length = slot->data.raw.bytes;
return( PSA_SUCCESS );
}
@ -1366,10 +1362,7 @@ static psa_status_t psa_internal_export_key( const psa_key_slot_t *slot,
}
if( ret < 0 )
{
/* If data_size is 0 then data may be NULL and then the
* call to memset would have undefined behavior. */
if( data_size != 0 )
memset( data, 0, data_size );
memset( data, 0, data_size );
return( mbedtls_to_psa_error( ret ) );
}
/* The mbedtls_pk_xxx functions write to the end of the buffer.
@ -1676,7 +1669,7 @@ static psa_status_t psa_finish_key_creation(
slot->attr.bits );
uint8_t *buffer = mbedtls_calloc( 1, buffer_size );
size_t length = 0;
if( buffer == NULL && buffer_size != 0 )
if( buffer == NULL )
return( PSA_ERROR_INSUFFICIENT_MEMORY );
status = psa_internal_export_key( slot,
buffer, buffer_size, &length,
@ -1685,8 +1678,7 @@ static psa_status_t psa_finish_key_creation(
status = psa_save_persistent_key( &slot->attr,
buffer, length );
if( buffer_size != 0 )
mbedtls_platform_zeroize( buffer, buffer_size );
mbedtls_platform_zeroize( buffer, buffer_size );
mbedtls_free( buffer );
}
}
@ -1826,6 +1818,12 @@ psa_status_t psa_import_key( const psa_key_attributes_t *attributes,
psa_key_slot_t *slot = NULL;
psa_se_drv_table_entry_t *driver = NULL;
/* Reject zero-length symmetric keys (including raw data key objects).
* This also rejects any key which might be encoded as an empty string,
* which is never valid. */
if( data_length == 0 )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_start_key_creation( PSA_KEY_CREATION_IMPORT, attributes,
handle, &slot, &driver );
if( status != PSA_SUCCESS )
@ -1957,7 +1955,7 @@ static psa_status_t psa_copy_key_material( const psa_key_slot_t *source,
buffer_size = PSA_KEY_EXPORT_MAX_SIZE( source->attr.type,
psa_get_key_slot_bits( source ) );
buffer = mbedtls_calloc( 1, buffer_size );
if( buffer == NULL && buffer_size != 0 )
if( buffer == NULL )
return( PSA_ERROR_INSUFFICIENT_MEMORY );
status = psa_internal_export_key( source, buffer, buffer_size, &length, 0 );
if( status != PSA_SUCCESS )
@ -1966,8 +1964,7 @@ static psa_status_t psa_copy_key_material( const psa_key_slot_t *source,
status = psa_import_key_into_slot( target, buffer, length );
exit:
if( buffer_size != 0 )
mbedtls_platform_zeroize( buffer, buffer_size );
mbedtls_platform_zeroize( buffer, buffer_size );
mbedtls_free( buffer );
return( status );
}
@ -3194,8 +3191,8 @@ static psa_status_t psa_rsa_verify( mbedtls_rsa_context *rsa,
if( status != PSA_SUCCESS )
return( status );
if( signature_length < mbedtls_rsa_get_len( rsa ) )
return( PSA_ERROR_BUFFER_TOO_SMALL );
if( signature_length != mbedtls_rsa_get_len( rsa ) )
return( PSA_ERROR_INVALID_SIGNATURE );
#if defined(MBEDTLS_PKCS1_V15)
if( PSA_ALG_IS_RSA_PKCS1V15_SIGN( alg ) )
@ -3350,6 +3347,12 @@ psa_status_t psa_asymmetric_sign( psa_key_handle_t handle,
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
*signature_length = signature_size;
/* Immediately reject a zero-length signature buffer. This guarantees
* that signature must be a valid pointer. (On the other hand, the hash
* buffer can in principle be empty since it doesn't actually have
* to be a hash.) */
if( signature_size == 0 )
return( PSA_ERROR_BUFFER_TOO_SMALL );
status = psa_get_key_from_slot( handle, &slot, PSA_KEY_USAGE_SIGN, alg );
if( status != PSA_SUCCESS )
@ -3425,7 +3428,7 @@ exit:
if( status == PSA_SUCCESS )
memset( signature + *signature_length, '!',
signature_size - *signature_length );
else if( signature_size != 0 )
else
memset( signature, '!', signature_size );
/* If signature_size is 0 then we have nothing to do. We must not call
* memset because signature may be NULL in this case. */
@ -4778,6 +4781,12 @@ psa_status_t psa_key_derivation_output_key( const psa_key_attributes_t *attribut
psa_status_t status;
psa_key_slot_t *slot = NULL;
psa_se_drv_table_entry_t *driver = NULL;
/* Reject any attempt to create a zero-length key so that we don't
* risk tripping up later, e.g. on a malloc(0) that returns NULL. */
if( psa_get_key_bits( attributes ) == 0 )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_start_key_creation( PSA_KEY_CREATION_DERIVE,
attributes, handle, &slot, &driver );
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
@ -5512,6 +5521,11 @@ psa_status_t psa_generate_key( const psa_key_attributes_t *attributes,
psa_key_slot_t *slot = NULL;
psa_se_drv_table_entry_t *driver = NULL;
/* Reject any attempt to create a zero-length key so that we don't
* risk tripping up later, e.g. on a malloc(0) that returns NULL. */
if( psa_get_key_bits( attributes ) == 0 )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_start_key_creation( PSA_KEY_CREATION_GENERATE,
attributes, handle, &slot, &driver );
if( status != PSA_SUCCESS )