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generate key ext: skip driver invocation with non-default method

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In the driver wrapper for psa_generate_key() and psa_generate_key_ext():

* Invoke the built-in code if using a non-default method, even if there
  might be an accelerator. This is ok because we only support non-default
  methods for RSA and we don't support driver-only RSA, therefore a
  non-default method will always have built-in code behind it.
* Return NOT_SUPPORTED if trying to use a non-default method with an opaque
  driver.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2024-02-14 23:07:33 +01:00
parent c81393b2ed
commit 69f11c8dfb
3 changed files with 29 additions and 5 deletions
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2
library/psa_crypto.c
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@ -6025,7 +6025,7 @@ exit:
static const psa_key_generation_method_t default_method = PSA_KEY_GENERATION_METHOD_INIT;
static int psa_key_generation_method_is_default(
int psa_key_generation_method_is_default(
const psa_key_generation_method_t *method,
size_t method_data_length)
{

12
library/psa_crypto_core.h
View file

@ -396,6 +396,18 @@ psa_status_t psa_export_public_key_internal(
const uint8_t *key_buffer, size_t key_buffer_size,
uint8_t *data, size_t data_size, size_t *data_length);
/** Whether a key generation method is the default.
*
* Calls to a key generation driver with a non-default method
* require a driver supporting custom methods.
*
* \param[in] method The key generation method to check.
* \param method_data_length Size of `method.data` in bytes.
*/
int psa_key_generation_method_is_default(
const psa_key_generation_method_t *method,
size_t method_data_length);
/**
* \brief Generate a key.
*

20
scripts/data_files/driver_templates/psa_crypto_driver_wrappers.h.jinja
View file

@ -738,8 +738,18 @@ static inline psa_status_t psa_driver_wrapper_generate_key(
psa_key_location_t location =
PSA_KEY_LIFETIME_GET_LOCATION(attributes->core.lifetime);
/* TODO: if method is non-default, we need a driver that supports
* passing a method. */
#if defined(PSA_WANT_KEY_TYPE_RSA_KEY_PAIR_GENERATE)
int is_default_method =
psa_key_generation_method_is_default(method, method_data_length);
if( location != PSA_KEY_LOCATION_LOCAL_STORAGE && !is_default_method )
{
/* We don't support passing a custom method to drivers yet. */
return PSA_ERROR_NOT_SUPPORTED;
}
#else
int is_default_method = 1;
(void) is_default_method;
#endif
/* Try dynamically-registered SE interface first */
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
@ -766,8 +776,10 @@ static inline psa_status_t psa_driver_wrapper_generate_key(
{
case PSA_KEY_LOCATION_LOCAL_STORAGE:
#if defined(PSA_CRYPTO_ACCELERATOR_DRIVER_PRESENT)
/* Transparent drivers are limited to generating asymmetric keys */
if( PSA_KEY_TYPE_IS_ASYMMETRIC( attributes->core.type ) )
/* Transparent drivers are limited to generating asymmetric keys. */
/* We don't support passing a custom method to drivers yet. */
if( PSA_KEY_TYPE_IS_ASYMMETRIC( attributes->core.type ) &&
is_default_method )
{
/* Cycle through all known transparent accelerators */
#if defined(PSA_CRYPTO_DRIVER_TEST)