commit 894edde9915bc34c814f5571d1b246f30a6337f7
author Andrzej Kurek <andrzej.kurek@arm.com> Thu Sep 29 06:31:14 2022 -0400
committer Andrzej Kurek <andrzej.kurek@arm.com> Wed Oct 19 08:35:08 2022 -0400
tree 1d5e817a270562615207518a7837d27106f45302
parent f502bcb13ed7f326ec488f5a4057647bec788957

Add tls prf handling when there's no SHA256 or SHA384

Return a null prf function pointer and check for it when populating transform.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>

library/ssl_tls.c

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index c36729f..50a233d 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4046,6 +4046,7 @@
     const unsigned char * const end = buf + len;
     size_t session_len;
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    tls_prf_fn prf_func = NULL;
 
     /*
      * The context should have been freshly setup or reset.
@@ -4131,6 +4132,10 @@
     ssl->transform_out = ssl->transform;
     ssl->transform_negotiate = NULL;
 
+    prf_func = ssl_tls12prf_from_cs( ssl->session->ciphersuite );
+    if( prf_func == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
     /* Read random bytes and populate structure */
     if( (size_t)( end - p ) < sizeof( ssl->transform->randbytes ) )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
@@ -4141,7 +4146,7 @@
 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC_ETM)
                   ssl->session->encrypt_then_mac,
 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC_ETM */
-                  ssl_tls12prf_from_cs( ssl->session->ciphersuite ),
+                  prf_func,
                   p, /* currently pointing to randbytes */
                   MBEDTLS_SSL_VERSION_TLS1_2, /* (D)TLS 1.2 is forced */
                   ssl->conf->endpoint,
@@ -7428,6 +7433,8 @@
  * Helper to get TLS 1.2 PRF from ciphersuite
  * (Duplicates bits of logic from ssl_set_handshake_prfs().)
  */
+#if defined(MBEDTLS_HAS_ALG_SHA_256_VIA_MD_OR_PSA_BASED_ON_USE_PSA) || \
+    defined(MBEDTLS_HAS_ALG_SHA_384_VIA_MD_OR_PSA_BASED_ON_USE_PSA)
 static tls_prf_fn ssl_tls12prf_from_cs( int ciphersuite_id )
 {
 #if defined(MBEDTLS_HAS_ALG_SHA_384_VIA_MD_OR_PSA_BASED_ON_USE_PSA)
@@ -7436,11 +7443,22 @@
 
     if( ciphersuite_info != NULL && ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
         return( tls_prf_sha384 );
-#else
-    (void) ciphersuite_id;
+    else
 #endif
-    return( tls_prf_sha256 );
+#if defined(MBEDTLS_HAS_ALG_SHA_256_VIA_MD_OR_PSA_BASED_ON_USE_PSA)
+    {
+        if( ciphersuite_info != NULL && ciphersuite_info->mac == MBEDTLS_MD_SHA256 )
+            return( tls_prf_sha256 );
+    }
+#endif
+#if !defined(MBEDTLS_HAS_ALG_SHA_384_VIA_MD_OR_PSA_BASED_ON_USE_PSA) && \
+    !defined(MBEDTLS_HAS_ALG_SHA_256_VIA_MD_OR_PSA_BASED_ON_USE_PSA)
+    (void) ciphersuite_info;
+#endif
+    return( NULL );
 }
+#endif /* MBEDTLS_HAS_ALG_SHA_256_VIA_MD_OR_PSA_BASED_ON_USE_PSA ||
+          MBEDTLS_HAS_ALG_SHA_384_VIA_MD_OR_PSA_BASED_ON_USE_PSA */
 #endif /* MBEDTLS_SSL_CONTEXT_SERIALIZATION */
 
 static mbedtls_tls_prf_types tls_prf_get_type( mbedtls_ssl_tls_prf_cb *tls_prf )