Set SSL_OP_NO_TICKET flag in SSL context for OpenSSL builds, to disable TLS stateless...

OpenVPN doesn't want or need SSL session renegotiation or
resumption, as it handles renegotiation on its own.

For this reason, OpenVPN always disables the SSL session cache:

SSL_CTX_set_session_cache_mode (ctx, SSL_SESS_CACHE_OFF)

However, even with the above code, stateless session resumption
is still possible unless explicitly disabled with the
SSL_OP_NO_TICKET flag.  This patch does this.

Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <1395017376-24554-1-git-send-email-james@openvpn.net>
URL: http://article.gmane.org/gmane.network.openvpn.devel/8346

Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/ssl_openssl.c b/src/openvpn/ssl_openssl.c
index f079652667920f6ccd2966797cc3e1cf664b870c..68a1d591ecea37ff7763769be3069be76eafe02c 100644 (file)
--- a/src/openvpn/ssl_openssl.c
+++ b/src/openvpn/ssl_openssl.c
@@ -180,7 +180,7 @@ tls_ctx_set_options (struct tls_root_ctx *ctx, unsigned int ssl_flags)
 
   /* process SSL options including minimum TLS version we will accept from peer */
   {
-    long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3;
+    long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_TICKET | SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3;
     const int tls_version_min = (ssl_flags >> SSLF_TLS_VERSION_SHIFT) & SSLF_TLS_VERSION_MASK;
     if (tls_version_min > TLS_VER_1_0)
       sslopt |= SSL_OP_NO_TLSv1;