From d6db9be598733f34c3734450bc943b5860b9a807 Mon Sep 17 00:00:00 2001
From: Andrzej Kurek <andrzej.kurek@mobica.com>
Date: Thu, 10 Jan 2019 05:27:10 -0500
Subject: [PATCH] Adapt mbedtls_ssl_get_key_exchange_md_tls1_2 to PSA hashing

---
 include/mbedtls/ssl_internal.h |  1 +
 library/ssl_tls.c              | 65 ++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+)

diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index fced2cbd7..a13feb55c 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -765,6 +765,7 @@ int mbedtls_ssl_get_key_exchange_md_ssl_tls( mbedtls_ssl_context *ssl,
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
     defined(MBEDTLS_SSL_PROTO_TLS1_2)
+// The hash buffer must have at least MBEDTLS_MD_MAX_SIZE bytes of length.
 int mbedtls_ssl_get_key_exchange_md_tls1_2( mbedtls_ssl_context *ssl,
                                             unsigned char *hash, size_t *hashlen,
                                             unsigned char *data, size_t data_len,
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 8fe93141f..99b99285e 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -50,6 +50,11 @@
 
 #include <string.h>
 
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+#include "mbedtls/psa_util.h"
+#include "psa/crypto.h"
+#endif
+
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
 #include "mbedtls/oid.h"
 #endif
@@ -9972,6 +9977,64 @@ exit:
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
     defined(MBEDTLS_SSL_PROTO_TLS1_2)
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+int mbedtls_ssl_get_key_exchange_md_tls1_2( mbedtls_ssl_context *ssl,
+                                            unsigned char *hash, size_t *hashlen,
+                                            unsigned char *data, size_t data_len,
+                                            mbedtls_md_type_t md_alg )
+{
+    int ret = 0;
+    psa_hash_operation_t hash_operation;
+    psa_algorithm_t hash_alg = mbedtls_psa_translate_md( md_alg );
+
+    if( ( ret = psa_hash_setup( &hash_operation, hash_alg ) ) != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "psa_hash_setup", ret );
+        goto exit;
+    }
+
+    if( ( ret = psa_hash_update( &hash_operation, ssl->handshake->randbytes, 64 ) ) != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "psa_hash_update", ret );
+        goto exit;
+    }
+
+    if( ( ret = psa_hash_update( &hash_operation, data, data_len ) ) != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "psa_hash_update", ret );
+        goto exit;
+    }
+
+    if( ( ret = psa_hash_finish( &hash_operation, hash, MBEDTLS_MD_MAX_SIZE, hashlen ) ) != PSA_SUCCESS )
+    {
+         MBEDTLS_SSL_DEBUG_RET( 1, "psa_hash_finish", ret );
+         goto exit;
+    }
+
+exit:
+    if( ret != 0 )
+    {
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+        switch(ret)
+        {
+            case PSA_ERROR_NOT_SUPPORTED:
+                return( MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE );
+            case PSA_ERROR_BAD_STATE: // Intentional fallthrough
+            case PSA_ERROR_BUFFER_TOO_SMALL:
+                return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
+            case PSA_ERROR_INSUFFICIENT_MEMORY:
+                return( MBEDTLS_ERR_MD_ALLOC_FAILED );
+            default:
+                return( MBEDTLS_ERR_MD_HW_ACCEL_FAILED );
+        }
+    }
+    return( 0 );
+}
+
+#else
+
 int mbedtls_ssl_get_key_exchange_md_tls1_2( mbedtls_ssl_context *ssl,
                                             unsigned char *hash, size_t *hashlen,
                                             unsigned char *data, size_t data_len,
@@ -10026,6 +10089,8 @@ exit:
 
     return( ret );
 }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
 #endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
           MBEDTLS_SSL_PROTO_TLS1_2 */