psa_crypto_random_impl: minor fixes

- define mbedtls_psa_random_context_t even when MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG
  is defined
- define mbedtls_psa_legacy_get_random as pointer to function instead
  of #define to make "check_names" test happy.

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>

library/psa_crypto.c

@@ -7373,12 +7373,16 @@ psa_status_t psa_generate_random(uint8_t *output,
 #else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
 
     while (output_size > 0) {
+        int ret = MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED;
         size_t request_size =
             (output_size > MBEDTLS_PSA_RANDOM_MAX_REQUEST ?
              MBEDTLS_PSA_RANDOM_MAX_REQUEST :
              output_size);
-        int ret = mbedtls_psa_legacy_get_random(&global_data.rng.drbg,
+#if defined(MBEDTLS_CTR_DRBG_C)
-                                                output, request_size);
+        ret = mbedtls_ctr_drbg_random(&global_data.rng.drbg, output, request_size);
+#elif defined(MBEDTLS_HMAC_DRBG_C)
+        ret = mbedtls_hmac_drbg_random(&global_data.rng.drbg, output, request_size);
+#endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */
         if (ret != 0) {
             return mbedtls_to_psa_error(ret);
         }

library/psa_crypto_random_impl.h

@@ -1,14 +1,6 @@
 /** \file psa_crypto_random_impl.h
  *
  * \brief PSA crypto random generator implementation abstraction.
- *
- * The definitions here need to be consistent with the declarations
- * in include/psa_util_internal.h. This file contains some redundant
- * declarations to increase the chance that a compiler will detect
- * inconsistencies if one file is changed without updating the other,
- * but not all potential inconsistencies can be enforced, so make sure
- * to check the public declarations and contracts in
- * include/psa_util_internal.h if you modify this file.
  */
 /*
  *  Copyright The Mbed TLS Contributors
@@ -20,7 +12,11 @@
 
 #include "psa_util_internal.h"
 
-#if !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
+#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
+
+typedef mbedtls_psa_external_random_context_t mbedtls_psa_random_context_t;
+
+#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
 
 #include "mbedtls/entropy.h"
 
@@ -54,7 +50,9 @@
 #endif
 
 #else /* !MBEDTLS_PSA_HMAC_DRBG_MD_TYPE && !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/
+
 #error "No DRBG module available for the psa_crypto module."
+
 #endif /* !MBEDTLS_PSA_HMAC_DRBG_MD_TYPE && !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/
 
 #if defined(MBEDTLS_CTR_DRBG_C)
@@ -63,14 +61,26 @@
 #include "mbedtls/hmac_drbg.h"
 #endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */
 
+/* The maximum number of bytes that mbedtls_psa_get_random() is expected to return. */
+#if defined(MBEDTLS_CTR_DRBG_C)
+#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_CTR_DRBG_MAX_REQUEST
+#elif defined(MBEDTLS_HMAC_DRBG_C)
+#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_HMAC_DRBG_MAX_REQUEST
+#endif
+
 #if defined(MBEDTLS_CTR_DRBG_C)
-#define mbedtls_psa_legacy_get_random       mbedtls_ctr_drbg_random
 typedef mbedtls_ctr_drbg_context            mbedtls_psa_drbg_context_t;
 #elif defined(MBEDTLS_HMAC_DRBG_C)
-#define mbedtls_psa_legacy_get_random       mbedtls_hmac_drbg_random
 typedef mbedtls_hmac_drbg_context           mbedtls_psa_drbg_context_t;
 #endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */
 
+typedef struct {
+    void (* entropy_init)(mbedtls_entropy_context *ctx);
+    void (* entropy_free)(mbedtls_entropy_context *ctx);
+    mbedtls_entropy_context entropy;
+    mbedtls_psa_drbg_context_t drbg;
+} mbedtls_psa_random_context_t;
+
 /** Initialize the PSA DRBG.
  *
  * \param p_rng        Pointer to the Mbed TLS DRBG state.
@@ -97,27 +107,6 @@ static inline void mbedtls_psa_drbg_free(mbedtls_psa_drbg_context_t *p_rng)
 #endif
 }
 
-/** The type of the PSA random generator context.
- *
- * The random generator context is composed of an entropy context and
- * a DRBG context.
- */
-typedef struct {
-    void (* entropy_init)(mbedtls_entropy_context *ctx);
-    void (* entropy_free)(mbedtls_entropy_context *ctx);
-    mbedtls_entropy_context entropy;
-    mbedtls_psa_drbg_context_t drbg;
-} mbedtls_psa_random_context_t;
-
-/** The maximum number of bytes that mbedtls_psa_get_random() is expected to
- * return.
- */
-#if defined(MBEDTLS_CTR_DRBG_C)
-#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_CTR_DRBG_MAX_REQUEST
-#elif defined(MBEDTLS_HMAC_DRBG_C)
-#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_HMAC_DRBG_MAX_REQUEST
-#endif
-
 /** Seed the PSA DRBG.
  *
  * \param entropy       An entropy context to read the seed from.
@@ -129,24 +118,15 @@ typedef struct {
  * \return              \c 0 on success.
  * \return              An Mbed TLS error code (\c MBEDTLS_ERR_xxx) on failure.
  */
-static inline int mbedtls_psa_drbg_seed(
+static inline int mbedtls_psa_drbg_seed(mbedtls_psa_drbg_context_t *drbg_ctx,
-    mbedtls_psa_drbg_context_t *drbg_ctx,
+                                        mbedtls_entropy_context *entropy,
-    mbedtls_entropy_context *entropy,
+                                        const unsigned char *custom, size_t len)
-    const unsigned char *custom, size_t len)
 {
 #if defined(MBEDTLS_CTR_DRBG_C)
-    return mbedtls_ctr_drbg_seed(drbg_ctx,
+    return mbedtls_ctr_drbg_seed(drbg_ctx, mbedtls_entropy_func, entropy, custom, len);
-                                 mbedtls_entropy_func,
-                                 entropy,
-                                 custom, len);
 #elif defined(MBEDTLS_HMAC_DRBG_C)
-    const mbedtls_md_info_t *md_info =
+    const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE);
-        mbedtls_md_info_from_type(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE);
+    return mbedtls_hmac_drbg_seed(drbg_ctx, md_info, mbedtls_entropy_func, entropy, custom, len);
-    return mbedtls_hmac_drbg_seed(drbg_ctx,
-                                  md_info,
-                                  mbedtls_entropy_func,
-                                  entropy,
-                                  custom, len);
 #endif
 }