Replace mbedtls_psa_random_state( ... ) by MBEDTLS_PSA_RANDOM_STATE
Hide the obtention of the pointer to the RNG state behind a macro.
To make it possible to use this macro in a module other than
psa_crypto.c, which will happen in the future, make sure that the
definition of the macro does not reference internal variables of
psa_crypto.c. For this purpose, in the internal-DRBG case, export a
symbol containing the address of the DRBG state.
When the RNG state is a pointer a DRBG state, just keep this pointer
in a variable: there's no need to store a pointer to a larger structure.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index b3d7eb4..bb38475 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -124,6 +124,11 @@
static psa_global_data_t global_data;
+#if !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
+mbedtls_psa_drbg_context_t *const mbedtls_psa_random_state =
+ &global_data.rng.drbg;
+#endif
+
#define GUARD_MODULE_INITIALIZED \
if( global_data.initialized == 0 ) \
return( PSA_ERROR_BAD_STATE );
@@ -884,7 +889,7 @@
/* Calculate the public key */
status = mbedtls_to_psa_error(
mbedtls_ecp_mul( &ecp->grp, &ecp->Q, &ecp->d, &ecp->grp.G,
- mbedtls_psa_get_random, mbedtls_psa_random_state( &global_data.rng ) ) );
+ mbedtls_psa_get_random, MBEDTLS_PSA_RANDOM_STATE ) );
if( status != PSA_SUCCESS )
return( status );
}
@@ -3667,7 +3672,7 @@
MBEDTLS_MD_NONE );
ret = mbedtls_rsa_pkcs1_sign( rsa,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ),
+ MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PRIVATE,
md_alg,
(unsigned int) hash_length,
@@ -3682,7 +3687,7 @@
mbedtls_rsa_set_padding( rsa, MBEDTLS_RSA_PKCS_V21, md_alg );
ret = mbedtls_rsa_rsassa_pss_sign( rsa,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ),
+ MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PRIVATE,
MBEDTLS_MD_NONE,
(unsigned int) hash_length,
@@ -3725,7 +3730,7 @@
MBEDTLS_MD_NONE );
ret = mbedtls_rsa_pkcs1_verify( rsa,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ),
+ MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PUBLIC,
md_alg,
(unsigned int) hash_length,
@@ -3740,7 +3745,7 @@
mbedtls_rsa_set_padding( rsa, MBEDTLS_RSA_PKCS_V21, md_alg );
ret = mbedtls_rsa_rsassa_pss_verify( rsa,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ),
+ MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PUBLIC,
MBEDTLS_MD_NONE,
(unsigned int) hash_length,
@@ -3798,7 +3803,7 @@
&ecp->d, hash,
hash_length, md_alg,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ) ) );
+ MBEDTLS_PSA_RANDOM_STATE ) );
}
else
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA) */
@@ -3807,7 +3812,7 @@
MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign( &ecp->grp, &r, &s, &ecp->d,
hash, hash_length,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ) ) );
+ MBEDTLS_PSA_RANDOM_STATE ) );
}
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &r,
@@ -3852,7 +3857,7 @@
{
MBEDTLS_MPI_CHK(
mbedtls_ecp_mul( &ecp->grp, &ecp->Q, &ecp->d, &ecp->grp.G,
- mbedtls_psa_get_random, mbedtls_psa_random_state( &global_data.rng ) ) );
+ mbedtls_psa_get_random, MBEDTLS_PSA_RANDOM_STATE ) );
}
ret = mbedtls_ecdsa_verify( &ecp->grp, hash, hash_length,
@@ -4153,7 +4158,7 @@
status = mbedtls_to_psa_error(
mbedtls_rsa_pkcs1_encrypt( rsa,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ),
+ MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PUBLIC,
input_length,
input,
@@ -4168,7 +4173,7 @@
status = mbedtls_to_psa_error(
mbedtls_rsa_rsaes_oaep_encrypt( rsa,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ),
+ MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PUBLIC,
salt, salt_length,
input_length,
@@ -4260,7 +4265,7 @@
status = mbedtls_to_psa_error(
mbedtls_rsa_pkcs1_decrypt( rsa,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ),
+ MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PRIVATE,
output_length,
input,
@@ -4276,7 +4281,7 @@
status = mbedtls_to_psa_error(
mbedtls_rsa_rsaes_oaep_decrypt( rsa,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ),
+ MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PRIVATE,
salt, salt_length,
output_length,
@@ -4510,7 +4515,7 @@
status = PSA_ERROR_BUFFER_TOO_SMALL;
goto exit;
}
- ret = mbedtls_psa_get_random( mbedtls_psa_random_state( &global_data.rng ),
+ ret = mbedtls_psa_get_random( MBEDTLS_PSA_RANDOM_STATE,
iv, operation->iv_size );
if( ret != 0 )
{
@@ -6127,7 +6132,7 @@
shared_secret_length,
shared_secret, shared_secret_size,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ) ) );
+ MBEDTLS_PSA_RANDOM_STATE ) );
if( status != PSA_SUCCESS )
goto exit;
if( PSA_BITS_TO_BYTES( bits ) != *shared_secret_length )
@@ -6336,7 +6341,7 @@
MBEDTLS_ENTROPY_SOURCE_STRONG );
#endif
- mbedtls_psa_drbg_init( mbedtls_psa_random_state( rng ) );
+ mbedtls_psa_drbg_init( MBEDTLS_PSA_RANDOM_STATE );
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}
@@ -6347,7 +6352,7 @@
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
memset( rng, 0, sizeof( *rng ) );
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
- mbedtls_psa_drbg_free( mbedtls_psa_random_state( rng ) );
+ mbedtls_psa_drbg_free( MBEDTLS_PSA_RANDOM_STATE );
rng->entropy_free( &rng->entropy );
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}
@@ -6362,7 +6367,8 @@
return( PSA_SUCCESS );
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
const unsigned char drbg_seed[] = "PSA";
- int ret = mbedtls_psa_drbg_seed( rng, drbg_seed, sizeof( drbg_seed ) - 1 );
+ int ret = mbedtls_psa_drbg_seed( &rng->entropy,
+ drbg_seed, sizeof( drbg_seed ) - 1 );
return mbedtls_to_psa_error( ret );
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}
@@ -6393,7 +6399,7 @@
while( output_size > MBEDTLS_PSA_RANDOM_MAX_REQUEST )
{
ret = mbedtls_psa_get_random(
- mbedtls_psa_random_state( &global_data.rng ),
+ MBEDTLS_PSA_RANDOM_STATE,
output, MBEDTLS_PSA_RANDOM_MAX_REQUEST );
if( ret != 0 )
return( mbedtls_to_psa_error( ret ) );
@@ -6401,7 +6407,7 @@
output_size -= MBEDTLS_PSA_RANDOM_MAX_REQUEST;
}
- ret = mbedtls_psa_get_random( mbedtls_psa_random_state( &global_data.rng ),
+ ret = mbedtls_psa_get_random( MBEDTLS_PSA_RANDOM_STATE,
output, output_size );
return( mbedtls_to_psa_error( ret ) );
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
@@ -6510,7 +6516,7 @@
mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, MBEDTLS_MD_NONE );
ret = mbedtls_rsa_gen_key( &rsa,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ),
+ MBEDTLS_PSA_RANDOM_STATE,
(unsigned int) bits,
exponent );
if( ret != 0 )
@@ -6556,7 +6562,7 @@
mbedtls_ecp_keypair_init( &ecp );
ret = mbedtls_ecp_gen_key( grp_id, &ecp,
mbedtls_psa_get_random,
- mbedtls_psa_random_state( &global_data.rng ) );
+ MBEDTLS_PSA_RANDOM_STATE );
if( ret != 0 )
{
mbedtls_ecp_keypair_free( &ecp );
diff --git a/library/psa_crypto_random.h b/library/psa_crypto_random.h
index 0f13c13..cc1222a 100644
--- a/library/psa_crypto_random.h
+++ b/library/psa_crypto_random.h
@@ -42,11 +42,7 @@
return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
}
-static inline void *mbedtls_psa_random_state( mbedtls_psa_random_context_t *rng )
-{
- (void) rng;
- return( NULL );
-}
+#define MBEDTLS_PSA_RANDOM_STATE NULL
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
@@ -135,13 +131,11 @@
/** Return random data.
*
* This function is suitable as the \p f_rng parameter to Mbed TLS functions
- * that require a random generator. Use mbedtls_psa_random_state() to
+ * that require a random generator. Use #MBEDTLS_PSA_RANDOM_STATE to
* obtain the \p p_rng parameter.
*
* \param p_rng The DRBG context. This must be
- * mbedtls_psa_random_state( \c rng )
- * where \c rng is a pointer to a
- * ::mbedtls_psa_random_context_t structure.
+ * #MBEDTLS_PSA_RANDOM_STATE.
* \param output The buffer to fill.
* \param output_len The length of the buffer in bytes.
* It must be at most #MBEDTLS_PSA_RANDOM_MAX_REQUEST.
@@ -170,21 +164,26 @@
#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_HMAC_DRBG_MAX_REQUEST
#endif
-/** Retrieve the DRBG state from the PSA RNG state.
+/** A pointer to the PSA DRBG state.
*
- * \param rng Pointer to the PSA random generator state.
- *
- * \return The DRBG state (\c p_rng argument ).
+ * This variable is only intended to be used through the macro
+ * #MBEDTLS_PSA_RANDOM_STATE.
*/
-static inline mbedtls_psa_drbg_context_t *mbedtls_psa_random_state(
- mbedtls_psa_random_context_t *rng )
-{
- return( &rng->drbg );
-}
+extern mbedtls_psa_drbg_context_t *const mbedtls_psa_random_state;
+
+/** A pointer to the PSA DRBG state.
+ *
+ * This macro expnds to an expression that is suitable as the \c p_rng
+ * parameter to pass to mbedtls_psa_get_random().
+ *
+ * This macro exists in all configurations where the psa_crypto module is
+ * enabled. Its expansion depends on the configuration.
+ */
+#define MBEDTLS_PSA_RANDOM_STATE mbedtls_psa_random_state
/** Seed the PSA DRBG.
*
- * \param rng DRBG context to be seeded.
+ * \param entropy An entropy context to read the seed from.
* \param custom The personalization string.
* This can be \c NULL, in which case the personalization
* string is empty regardless of the value of \p len.
@@ -194,21 +193,21 @@
* \return An Mbed TLS error code (\c MBEDTLS_ERR_xxx) on failure.
*/
static inline int mbedtls_psa_drbg_seed(
- mbedtls_psa_random_context_t *rng,
+ mbedtls_entropy_context *entropy,
const unsigned char *custom, size_t len )
{
#if defined(MBEDTLS_CTR_DRBG_C)
- return( mbedtls_ctr_drbg_seed( mbedtls_psa_random_state( rng ),
+ return( mbedtls_ctr_drbg_seed( MBEDTLS_PSA_RANDOM_STATE,
mbedtls_entropy_func,
- &rng->entropy,
+ entropy,
custom, len ) );
#elif defined(MBEDTLS_HMAC_DRBG_C)
const mbedtls_md_info_t *md_info =
mbedtls_md_info_from_type( MBEDTLS_PSA_HMAC_DRBG_MD_TYPE );
- return( mbedtls_hmac_drbg_seed( mbedtls_psa_random_state( rng ),
+ return( mbedtls_hmac_drbg_seed( MBEDTLS_PSA_RANDOM_STATE,
md_info,
mbedtls_entropy_func,
- &rng->entropy,
+ entropy,
custom, len ) );
#endif
}