Add SSLSessionTickets (on|off).

It controls the use of TLS session tickets
(RFC 5077). Default is unchanged (on).

Using session tickets without restarting
the web server with an appropriate frequency
(e.g. daily) compromises perfect forward
secrecy.

As long as we do not have a nice key management
there should be a way to deactivate session
tickets.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1650310 13f79535-47bb-0310-9956-ffa450edef68

docs/manual/mod/mod_ssl.xml

@@ -2589,6 +2589,27 @@ CRIME attack).</p>
 </usage>
 </directivesynopsis>
 
+<directivesynopsis>
+<name>SSLSessionTickets</name>
+<description>Enable or disable use of TLS session tickets</description>
+<syntax>SSLSessionTickets on|off</syntax>
+<default>SSLCompression on</default>
+<contextlist><context>server config</context>
+<context>virtual host</context></contextlist>
+<compatibility>Available in httpd 2.4.11 and later, if using OpenSSL 0.9.8f
+or later.</compatibility>
+
+<usage>
+<p>This directive allows to enable or disable the use of TLS session tickets
+(RFC 5077).</p>
+<note type="warning">
+<p>TLS session tickets are enabled by default. Using them without restarting
+the web server with an appropriate frequency (e.g. daily) compromises perfect
+forward secrecy.</p>
+</note>
+</usage>
+</directivesynopsis>
+
 <directivesynopsis>
 <name>SSLOpenSSLConfCmd</name>
 <description>Configure OpenSSL parameters through its <em>SSL_CONF</em> API</description>

modules/ssl/mod_ssl.c

@@ -148,6 +148,9 @@ static const command_rec ssl_config_cmds[] = {
     SSL_CMD_SRV(Compression, FLAG,
                 "Enable SSL level compression "
                 "(`on', `off')")
+    SSL_CMD_SRV(SessionTickets, FLAG,
+                "Enable or disable TLS session tickets"
+                "(`on', `off')")
     SSL_CMD_SRV(InsecureRenegotiation, FLAG,
                 "Enable support for insecure renegotiation")
     SSL_CMD_ALL(UserName, TAKE1,

modules/ssl/ssl_engine_config.c

@@ -222,6 +222,7 @@ static SSLSrvConfigRec *ssl_config_server_new(apr_pool_t *p)
 #ifndef OPENSSL_NO_COMP
     sc->compression            = UNSET;
 #endif
+    sc->session_tickets        = UNSET;
 
     modssl_ctx_init_proxy(sc, p);
 
@@ -356,6 +357,7 @@ void *ssl_config_server_merge(apr_pool_t *p, void *basev, void *addv)
 #ifndef OPENSSL_NO_COMP
     cfgMergeBool(compression);
 #endif
+    cfgMergeBool(session_tickets);
 
     modssl_ctx_cfg_merge_proxy(p, base->proxy, add->proxy, mrg->proxy);
 
@@ -733,6 +735,17 @@ const char *ssl_cmd_SSLHonorCipherOrder(cmd_parms *cmd, void *dcfg, int flag)
 #endif
 }
 
+const char *ssl_cmd_SSLSessionTickets(cmd_parms *cmd, void *dcfg, int flag)
+{
+    SSLSrvConfigRec *sc = mySrvConfig(cmd->server);
+#ifndef SSL_OP_NO_TICKET
+    return "This version of OpenSSL does not support using "
+           "SSLSessionTickets.";
+#endif
+    sc->session_tickets = flag ? TRUE : FALSE;
+    return NULL;
+}
+
 const char *ssl_cmd_SSLInsecureRenegotiation(cmd_parms *cmd, void *dcfg, int flag)
 {
 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION

modules/ssl/ssl_engine_init.c

@@ -574,6 +574,16 @@ static apr_status_t ssl_init_ctx_protocol(server_rec *s,
     }
 #endif
 
+#ifdef SSL_OP_NO_TICKET
+    /*
+     * Configure using RFC 5077 TLS session tickets
+     * for session resumption.
+     */
+    if (sc->session_tickets == FALSE) {
+        SSL_CTX_set_options(ctx, SSL_OP_NO_TICKET);
+    }
+#endif
+
 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
     if (sc->insecure_reneg == TRUE) {
         SSL_CTX_set_options(ctx, SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION);

modules/ssl/ssl_private.h

@@ -648,6 +648,7 @@ struct SSLSrvConfigRec {
 #ifndef OPENSSL_NO_COMP
     BOOL             compression;
 #endif
+    BOOL             session_tickets;
 };
 
 /**
@@ -702,6 +703,7 @@ const char  *ssl_cmd_SSLCARevocationFile(cmd_parms *, void *, const char *);
 const char  *ssl_cmd_SSLCARevocationCheck(cmd_parms *, void *, const char *);
 const char  *ssl_cmd_SSLHonorCipherOrder(cmd_parms *cmd, void *dcfg, int flag);
 const char  *ssl_cmd_SSLCompression(cmd_parms *, void *, int flag);
+const char  *ssl_cmd_SSLSessionTickets(cmd_parms *, void *, int flag);
 const char  *ssl_cmd_SSLVerifyClient(cmd_parms *, void *, const char *);
 const char  *ssl_cmd_SSLVerifyDepth(cmd_parms *, void *, const char *);
 const char  *ssl_cmd_SSLSessionCache(cmd_parms *, void *, const char *);