Merge pull request #8528 from yanrayw/issue/6933/parse-max_early_data_size

TLS1.3 EarlyData: client: parse max_early_data_size

library/ssl_tls.c

@@ -306,7 +306,7 @@ static int resize_buffer(unsigned char **buffer, size_t len_new, size_t *len_old
 {
     unsigned char *resized_buffer = mbedtls_calloc(1, len_new);
     if (resized_buffer == NULL) {
-        return -1;
+        return MBEDTLS_ERR_SSL_ALLOC_FAILED;
     }
 
     /* We want to copy len_new bytes when downsizing the buffer, and
@@ -2623,8 +2623,7 @@ static int ssl_tls13_session_load(mbedtls_ssl_session *session,
 
 #if defined(MBEDTLS_SSL_CLI_C)
     if (session->endpoint == MBEDTLS_SSL_IS_CLIENT) {
-#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) && \
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
-        defined(MBEDTLS_SSL_SESSION_TICKETS)
         size_t hostname_len;
         /* load host name */
         if (end - p < 2) {
@@ -2644,8 +2643,7 @@ static int ssl_tls13_session_load(mbedtls_ssl_session *session,
             memcpy(session->hostname, p, hostname_len);
             p += hostname_len;
         }
-#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION &&
+#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
-          MBEDTLS_SSL_SESSION_TICKETS */
 
 #if defined(MBEDTLS_HAVE_TIME)
         if (end - p < 8) {

library/ssl_tls13_client.c

@@ -2647,6 +2647,37 @@ static int ssl_tls13_handshake_wrapup(mbedtls_ssl_context *ssl)
 
 #if defined(MBEDTLS_SSL_SESSION_TICKETS)
 
+#if defined(MBEDTLS_SSL_EARLY_DATA)
+/* From RFC 8446 section 4.2.10
+ *
+ * struct {
+ *     select (Handshake.msg_type) {
+ *         case new_session_ticket:   uint32 max_early_data_size;
+ *         ...
+ *     };
+ * } EarlyDataIndication;
+ */
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_tls13_parse_new_session_ticket_early_data_ext(
+    mbedtls_ssl_context *ssl,
+    const unsigned char *buf,
+    const unsigned char *end)
+{
+    mbedtls_ssl_session *session = ssl->session;
+
+    MBEDTLS_SSL_CHK_BUF_READ_PTR(buf, end, 4);
+
+    session->max_early_data_size = MBEDTLS_GET_UINT32_BE(buf, 0);
+    mbedtls_ssl_session_set_ticket_flags(
+        session, MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA);
+    MBEDTLS_SSL_DEBUG_MSG(
+        3, ("received max_early_data_size: %u",
+            (unsigned int) session->max_early_data_size));
+
+    return 0;
+}
+#endif /* MBEDTLS_SSL_EARLY_DATA */
+
 MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_parse_new_session_ticket_exts(mbedtls_ssl_context *ssl,
                                                    const unsigned char *buf,
@@ -2680,15 +2711,12 @@ static int ssl_tls13_parse_new_session_ticket_exts(mbedtls_ssl_context *ssl,
         switch (extension_type) {
 #if defined(MBEDTLS_SSL_EARLY_DATA)
             case MBEDTLS_TLS_EXT_EARLY_DATA:
-                if (extension_data_len != 4) {
+                ret = ssl_tls13_parse_new_session_ticket_early_data_ext(
-                    MBEDTLS_SSL_PEND_FATAL_ALERT(
+                    ssl, p, p + extension_data_len);
-                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
+                if (ret != 0) {
-                        MBEDTLS_ERR_SSL_DECODE_ERROR);
+                    MBEDTLS_SSL_DEBUG_RET(
-                    return MBEDTLS_ERR_SSL_DECODE_ERROR;
+                        1, "ssl_tls13_parse_new_session_ticket_early_data_ext",
-                }
+                        ret);
-                if (ssl->session != NULL) {
-                    ssl->session->ticket_flags |=
-                        MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA;
                 }
                 break;
 #endif /* MBEDTLS_SSL_EARLY_DATA */

tests/opt-testcases/tls13-misc.sh

@@ -261,9 +261,11 @@ requires_all_configs_enabled MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE \
 requires_any_configs_enabled MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED \
                              MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED
 run_test    "TLS 1.3 m->G: EarlyData: basic check, good" \
-            "$G_NEXT_SRV -d 10 --priority=NORMAL:-VERS-ALL:+VERS-TLS1.3:+CIPHER-ALL:+ECDHE-PSK:+PSK --earlydata --disable-client-cert" \
+            "$G_NEXT_SRV -d 10 --priority=NORMAL:-VERS-ALL:+VERS-TLS1.3:+CIPHER-ALL:+ECDHE-PSK:+PSK \
+                         --earlydata --maxearlydata 16384 --disable-client-cert" \
             "$P_CLI debug_level=4 early_data=1 reco_mode=1 reconnect=1 reco_delay=900" \
             0 \
+            -c "received max_early_data_size: 16384" \
             -c "Reconnecting with saved session" \
             -c "NewSessionTicket: early_data(42) extension received." \
             -c "ClientHello: early_data(42) extension exists." \