Provide SSL_OP_NO_RENEGOTIATION and SSL_OP_ALLOW_CLIENT_RENEGOTIATION.

In January 2017 we added SSL_OP_NO_CLIENT_RENEGOTIATION, which results in a
SSL_AD_NO_RENEGOTIATION fatal alert if a ClientHello message is seen on an
active connection (client initiated renegotation). Then in May 2017 OpenSSL
added SSL_OP_NO_RENEGOTIATION, which results in a SSL_AD_NO_RENEGOTIATION
warning alert if a server receives a ClientHello on an active connection
(client initiated renegotation), or a client receives a HelloRequest
(server requested renegotation). This option also causes calls to
SSL_renegotiate() and SSL_renegotiate_abbreviated() to fail. Then in 2021,
OpenSSL also added SSL_OP_ALLOW_CLIENT_RENEGOTIATION, which trumps
SSL_OP_NO_RENEGOTIATION but only for incoming ClientHello messages
(apparently unsetting SSL_OP_NO_RENEGOTIATION is too hard).

Provide SSL_OP_NO_RENEGOTIATION and SSL_OP_ALLOW_CLIENT_RENEGOTIATION,
primarily to make life easier for ports. If SSL_OP_NO_CLIENT_RENEGOTIATION
is set it will take precedence and render SSL_OP_ALLOW_CLIENT_RENEGOTIATION
ineffective. The rest of the behaviour should match OpenSSL, with the
exception of ClientHellos triggering fatal alerts instead of warnings.

ok tb@

1 files changed, 11 insertions, 1 deletions

diff --git a/src/lib/libssl/ssl_lib.c b/src/lib/libssl/ssl_lib.c
index 63d72baf8e..ce68981493 100644
--- a/src/lib/libssl/ssl_lib.c
+++ b/src/lib/libssl/ssl_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_lib.c,v 1.330 2024/09/22 14:59:48 tb Exp $ */
+/* $OpenBSD: ssl_lib.c,v 1.331 2025/03/12 14:03:55 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1308,6 +1308,11 @@ LSSL_ALIAS(SSL_shutdown);
 int
 SSL_renegotiate(SSL *s)
 {
+        if ((s->options & SSL_OP_NO_RENEGOTIATION) != 0) {
+                SSLerror(s, SSL_R_NO_RENEGOTIATION);
+                return 0;
+        }
+
         if (s->renegotiate == 0)
                 s->renegotiate = 1;
 
@@ -1320,6 +1325,11 @@ LSSL_ALIAS(SSL_renegotiate);
 int
 SSL_renegotiate_abbreviated(SSL *s)
 {
+        if ((s->options & SSL_OP_NO_RENEGOTIATION) != 0) {
+                SSLerror(s, SSL_R_NO_RENEGOTIATION);
+                return 0;
+        }
+
         if (s->renegotiate == 0)
                 s->renegotiate = 1;