various improvement

- improve change log entry
- improve comments
- remove unnecessary statement
- change type of client_age

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

ChangeLog.d/gnutls_anti_replay_fail.txt

@@ -1,4 +1,5 @@
 Bugfix
-    * Fixes #6623. That is time unit issue. The unit of ticket age is seconds in
+    * Switch to milliseconds as the unit for ticket creation and reception time
-      MBedTLS and milliseconds in GnuTLS. If the real age is 10ms, it might be
+      instead of seconds. That avoids rounding errors when computing the age of
-      1s(1000ms), as a result, the age of MBedTLS is bigger than GnuTLS server.
+      tickets compared to peer using a millisecond clock (observed with GnuTLS).
+      Fixes #6623.

library/ssl_tls13_server.c

@@ -113,7 +113,7 @@ static int ssl_tls13_offered_psks_check_identity_match_ticket(
 #if defined(MBEDTLS_HAVE_TIME)
     mbedtls_ms_time_t now;
     mbedtls_ms_time_t server_age;
-    mbedtls_ms_time_t client_age;
+    uint32_t client_age;
     mbedtls_ms_time_t age_diff;
 #endif
 
@@ -195,8 +195,8 @@ static int ssl_tls13_offered_psks_check_identity_match_ticket(
 
     if (now < session->ticket_creation_time) {
         MBEDTLS_SSL_DEBUG_MSG(
-            3, ("Invalid ticket start time ( now = %" MBEDTLS_PRINTF_MS_TIME
+            3, ("Invalid ticket creation time ( now = %" MBEDTLS_PRINTF_MS_TIME
-                ", start = %" MBEDTLS_PRINTF_MS_TIME " )",
+                ", creation_time = %" MBEDTLS_PRINTF_MS_TIME " )",
                 now, session->ticket_creation_time));
         goto exit;
     }
@@ -233,7 +233,7 @@ static int ssl_tls13_offered_psks_check_identity_match_ticket(
      *       sync up their system time every 6000/360/2~=8 hours.
      */
     client_age = obfuscated_ticket_age - session->ticket_age_add;
-    age_diff = server_age - client_age;
+    age_diff = server_age - (mbedtls_ms_time_t)client_age;
     if (age_diff < -MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE ||
         age_diff > MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE) {
         MBEDTLS_SSL_DEBUG_MSG(

programs/ssl/ssl_server2.c

@@ -1430,14 +1430,14 @@ int dummy_ticket_parse(void *p_ticket, mbedtls_ssl_session *session,
                                             (7 * 24 * 3600 * 1000 + 1000);
             break;
         case 5:
-            /* Ticket is valid, but client age is below the upper bound of tolerance window. */
+            /* Ticket is valid, but client age is below the lower bound of the tolerance window. */
             session->ticket_age_add += MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE + 4 * 1000;
             /* Make sure the execution time does not affect the result */
             session->ticket_creation_time = mbedtls_ms_time();
             break;
 
         case 6:
-            /* Ticket is valid, but client age is beyond the lower bound of tolerance window. */
+            /* Ticket is valid, but client age is beyond the upper bound of the tolerance window. */
             session->ticket_age_add -= MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE + 4 * 1000;
             /* Make sure the execution time does not affect the result */
             session->ticket_creation_time = mbedtls_ms_time();

tests/suites/test_suite_ssl.function

@@ -2189,7 +2189,6 @@ void ssl_serialize_session_save_buf_size(int ticket_len, char *crt_file,
 
     /* Prepare dummy session and get serialized size */
     ((void) endpoint_type);
-    ((void) tls_version);
     ((void) ticket_len);
     ((void) crt_file);
 
@@ -2250,7 +2249,6 @@ void ssl_serialize_session_load_buf_size(int ticket_len, char *crt_file,
 
     /* Prepare serialized session data */
     ((void) endpoint_type);
-    ((void) tls_version);
     ((void) ticket_len);
     ((void) crt_file);
 
@@ -2323,7 +2321,6 @@ void ssl_session_serialize_version_check(int corrupt_major,
     mbedtls_ssl_session_init(&session);
     USE_PSA_INIT();
     ((void) endpoint_type);
-    ((void) tls_version);
 
     switch (tls_version) {
 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)