commit 6ba9f1c959cdcb30e0da23c1a7ced1ceb85e73a6
author Jerry Yu <jerry.h.yu@arm.com> Thu Aug 04 17:53:25 2022 +0800
committer Jerry Yu <jerry.h.yu@arm.com> Mon Oct 31 16:41:42 2022 +0800
tree 130582f9267e7abde748469f4f881960dba25db5
parent 2c5363e58b92c245e03dd0ad3997622d6bedf320

Add extension check for NewSessionTicket

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>

library/ssl_tls13_client.c

diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index f42e591..1abe09e 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -2565,9 +2565,12 @@
                                                     const unsigned char *end )
 {
     const unsigned char *p = buf;
+    uint32_t extensions_present;
 
     ((void) ssl);
 
+    extensions_present = MBEDTLS_SSL_EXT_NONE;
+
     while( p < end )
     {
         unsigned int extension_type;
@@ -2580,6 +2583,27 @@
 
         MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, extension_data_len );
 
+        /* RFC 8446 page 35
+         *
+         * If an implementation receives an extension which it recognizes and which
+         * is not specified for the message in which it appears, it MUST abort the
+         * handshake with an "illegal_parameter" alert.
+         */
+        extensions_present |= mbedtls_tls13_get_extension_mask( extension_type );
+        MBEDTLS_SSL_DEBUG_MSG( 3,
+                    ( "NewSessionTicket : received %s(%u) extension",
+                      mbedtls_tls13_get_extension_name( extension_type ),
+                      extension_type ) );
+        if( ( extensions_present & MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_NST ) == 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG(
+                3, ( "forbidden extension received." ) );
+            MBEDTLS_SSL_PEND_FATAL_ALERT(
+                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+                MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+            return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+        }
+
         switch( extension_type )
         {
             case MBEDTLS_TLS_EXT_EARLY_DATA:
@@ -2587,11 +2611,18 @@
                 break;
 
             default:
+                MBEDTLS_SSL_DEBUG_MSG( 3,
+                    ( "NewSessionTicket : received %s(%u) extension ( ignored )",
+                      mbedtls_tls13_get_extension_name( extension_type ),
+                      extension_type ) );
                 break;
         }
+
         p +=  extension_data_len;
     }
 
+    MBEDTLS_SSL_TLS1_3_PRINT_EXTS( 3, "NewSessionTicket", extensions_present );
+
     return( 0 );
 }