generate/derive key ext: pass method_data_length rather than method_length
Instead of passing the size of the whole structure, just pass the data
length and let the implementation worry about adding the size of the
structure. The intent with passing the structure size was to allow
the client code in a client-server implementation to know nothing
about the structure and just copy the bytes to the server. But that was not
really a useful consideration since the application has to know the
structure layout, so it has to be available in the client implementation's
headers. Passing the method data length makes life simpler for everyone by
not having to worry about possible padding at the end of the structure, and
removes a potential error condition
(method_length < sizeof(psa_key_generation_method_t)).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function
index 34baa1b..e946f4e 100644
--- a/tests/suites/test_suite_psa_crypto.function
+++ b/tests/suites/test_suite_psa_crypto.function
@@ -1310,21 +1310,25 @@
#endif /* PSA_WANT_KEY_TYPE_RSA_KEY_PAIR_GENERATE */
static int setup_key_generation_method(psa_key_generation_method_t **method,
- size_t *method_length,
- int64_t flags_arg,
+ size_t *method_data_length,
+ int flags_arg,
const data_t *method_data)
{
- if (flags_arg >= 0) {
- *method_length = sizeof(**method) + method_data->len;
- *method = mbedtls_calloc(1, *method_length);
- TEST_ASSERT(*method != NULL);
- (*method)->flags = (uint32_t) flags_arg;
- memcpy((*method)->data, method_data->x, method_data->len);
- } else if (sizeof(**method) + flags_arg > 0) {
- *method_length = sizeof(**method) + flags_arg;
- *method = mbedtls_calloc(1, *method_length);
- TEST_ASSERT(*method != NULL);
- }
+ *method_data_length = method_data->len;
+ /* If there are N bytes of padding at the end of
+ * psa_key_generation_method_t, then it's enough to allocate
+ * MIN(sizeof(psa_key_generation_method_t),
+ * offsetof(psa_key_generation_method_t, data) + method_data_length).
+ *
+ * For simplicity, here, we allocate up to N more bytes than necessary.
+ * In practice, the current layout of psa_key_generation_method_t
+ * makes padding extremely unlikely, so we don't worry about testing
+ * that the library code doesn't try to access these extra N bytes.
+ */
+ *method = mbedtls_calloc(1, sizeof(**method) + *method_data_length);
+ TEST_ASSERT(*method != NULL);
+ (*method)->flags = (uint32_t) flags_arg;
+ memcpy((*method)->data, method_data->x, method_data->len);
return 1;
exit:
return 0;
@@ -9335,7 +9339,7 @@
data_t *input1,
data_t *input2,
int key_type_arg, int bits_arg,
- int64_t flags_arg, /*negative for truncated method*/
+ int flags_arg,
data_t *method_data,
psa_status_t expected_status,
data_t *expected_export)
@@ -9346,7 +9350,7 @@
const psa_key_type_t key_type = key_type_arg;
const size_t bits = bits_arg;
psa_key_generation_method_t *method = NULL;
- size_t method_length = 0;
+ size_t method_data_length = 0;
psa_key_derivation_operation_t operation = PSA_KEY_DERIVATION_OPERATION_INIT;
const size_t export_buffer_size =
PSA_EXPORT_KEY_OUTPUT_SIZE(key_type, bits);
@@ -9376,13 +9380,13 @@
psa_set_key_algorithm(&derived_attributes, 0);
psa_set_key_type(&derived_attributes, key_type);
psa_set_key_bits(&derived_attributes, bits);
- if (!setup_key_generation_method(&method, &method_length,
+ if (!setup_key_generation_method(&method, &method_data_length,
flags_arg, method_data)) {
goto exit;
}
TEST_EQUAL(psa_key_derivation_output_key_ext(&derived_attributes, &operation,
- method, method_length,
+ method, method_data_length,
&derived_key),
expected_status);
@@ -9924,7 +9928,7 @@
int bits_arg,
int usage_arg,
int alg_arg,
- int64_t flags_arg, /*negative for truncated method*/
+ int flags_arg,
data_t *method_data,
int expected_status_arg)
{
@@ -9936,7 +9940,7 @@
psa_status_t expected_status = expected_status_arg;
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
psa_key_generation_method_t *method = NULL;
- size_t method_length = 0;
+ size_t method_data_length = 0;
psa_key_attributes_t got_attributes = PSA_KEY_ATTRIBUTES_INIT;
PSA_ASSERT(psa_crypto_init());
@@ -9946,14 +9950,14 @@
psa_set_key_type(&attributes, type);
psa_set_key_bits(&attributes, bits);
- if (!setup_key_generation_method(&method, &method_length,
+ if (!setup_key_generation_method(&method, &method_data_length,
flags_arg, method_data)) {
goto exit;
}
/* Generate a key */
psa_status_t status = psa_generate_key_ext(&attributes,
- method, method_length,
+ method, method_data_length,
&key);
TEST_EQUAL(status, expected_status);
@@ -9997,11 +10001,6 @@
psa_key_generation_method_t zero;
memset(&zero, 0, sizeof(zero));
- /* In order for sizeof(psa_key_generation_method_t) to mean
- * empty data, there must not be any padding in the structure:
- * the size of the structure must be the offset of the data field. */
- TEST_EQUAL(sizeof(zero), offsetof(psa_key_generation_method_t, data));
-
TEST_EQUAL(func.flags, 0);
TEST_EQUAL(init.flags, 0);
TEST_EQUAL(zero.flags, 0);