Make the anti-replay feature optional

Fixes #6389
Reviewed-by: NViktor Dukhovni <viktor@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6469)

include/openssl/ssl.h

@@ -368,6 +368,12 @@ typedef int (*SSL_verify_cb)(int preverify_ok, X509_STORE_CTX *x509_ctx);
  */
 # define SSL_OP_TLS_ROLLBACK_BUG                         0x00800000U
 
+/*
+ * Switches off automatic TLSv1.3 anti-replay protection for early data. This
+ * is a server-side option only (no effect on the client).
+ */
+# define SSL_OP_NO_ANTI_REPLAY                           0x01000000U
+
 # define SSL_OP_NO_SSLv3                                 0x02000000U
 # define SSL_OP_NO_TLSv1                                 0x04000000U
 # define SSL_OP_NO_TLSv1_2                               0x08000000U

ssl/ssl_lib.c

@@ -3381,7 +3381,8 @@ void ssl_update_cache(SSL *s, int mode)
         if ((i & SSL_SESS_CACHE_NO_INTERNAL_STORE) == 0
                 && (!SSL_IS_TLS13(s)
                     || !s->server
-                    || s->max_early_data > 0
+                    || (s->max_early_data > 0
+                        && (s->options & SSL_OP_NO_ANTI_REPLAY) == 0)
                     || s->session_ctx->remove_session_cb != NULL
                     || (s->options & SSL_OP_NO_TICKET) != 0))
             SSL_CTX_add_session(s->session_ctx, s->session);

ssl/ssl_locl.h

@@ -1205,6 +1205,9 @@ struct ssl_st {
 # endif
     SSL_psk_find_session_cb_func psk_find_session_cb;
     SSL_psk_use_session_cb_func psk_use_session_cb;
+
+    int (*allow_early_data_cb)(SSL *s, SSL_SESSION *sess);
+
     SSL_CTX *ctx;
     /* Verified chain of peer */
     STACK_OF(X509) *verified_chain;

ssl/statem/extensions_srvr.c

@@ -1165,7 +1165,8 @@ int tls_parse_ctos_psk(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
              * is no point in using full stateless tickets.
              */
             if ((s->options & SSL_OP_NO_TICKET) != 0
-                    || s->max_early_data > 0)
+                    || (s->max_early_data > 0
+                        && (s->options & SSL_OP_NO_ANTI_REPLAY) == 0))
                 ret = tls_get_stateful_ticket(s, &identity, &sess);
             else
                 ret = tls_decrypt_ticket(s, PACKET_data(&identity),
@@ -1189,6 +1190,7 @@ int tls_parse_ctos_psk(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
 
             /* Check for replay */
             if (s->max_early_data > 0
+                    && (s->options & SSL_OP_NO_ANTI_REPLAY) == 0
                     && !SSL_CTX_remove_session(s->session_ctx, sess)) {
                 SSL_SESSION_free(sess);
                 sess = NULL;

ssl/statem/statem_srvr.c

@@ -4086,8 +4086,10 @@ int tls_construct_new_session_ticket(SSL *s, WPACKET *pkt)
      * SSL_OP_NO_TICKET is set - we are caching tickets anyway so there
      * is no point in using full stateless tickets.
      */
-    if (((s->options & SSL_OP_NO_TICKET) != 0 || s->max_early_data > 0)
-            && SSL_IS_TLS13(s)) {
+    if (SSL_IS_TLS13(s)
+            && ((s->options & SSL_OP_NO_TICKET) != 0
+                || (s->max_early_data > 0
+                    && (s->options & SSL_OP_NO_ANTI_REPLAY) == 0))) {
         if (!construct_stateful_ticket(s, pkt, age_add_u.age_add, tick_nonce)) {
             /* SSLfatal() already called */
             goto err;