MINOR: ssl: add support for 'curves' keyword on server lines

This patch implements the 'curves' keyword on server lines as well as
the 'ssl-default-server-curves' keyword in the global section.

It also add the keyword on the server line in the ssl_curves reg-test.

These keywords allow the configuration of the curves list for a server.

doc/configuration.txt

@@ -1123,6 +1123,7 @@ The following keywords are supported in the "global" section :
    - ssl-default-server-ciphers
    - ssl-default-server-ciphersuites
    - ssl-default-server-client-sigalgs
+   - ssl-default-server-curves
    - ssl-default-server-options
    - ssl-default-server-sigalgs
    - ssl-dh-param-file
@@ -2336,6 +2337,13 @@ ssl-default-server-client-sigalgs <sigalgs>
   versions. It is not recommended to change this setting unless compatibility
   with a middlebox is required.
 
+ssl-default-server-curves <curves>
+  This setting is only available when support for OpenSSL was built in. It sets
+  the default string describing the list of elliptic curves algorithms ("curve
+  suite") that are negotiated during the SSL/TLS handshake with ECDHE. The format
+  of the string is a colon-delimited list of curve name.
+  Please check the "server" keyword for more information.
+
 ssl-default-server-options [<option>]...
   This setting is only available when support for OpenSSL was built in. It sets
   default ssl-options to force on all "server" lines. Please check the "server"
@@ -16060,6 +16068,13 @@ crt <cert>
   at the same path suffixed by a ".key" (provided the "ssl-load-extra-files"
   option is set accordingly).
 
+curves <curves>
+  This setting is only available when support for OpenSSL was built in. It sets
+  the string describing the list of elliptic curves algorithms ("curve suite")
+  that are negotiated during the SSL/TLS handshake with ECDHE. The format of the
+  string is a colon-delimited list of curve name.
+  Example: "X25519:P-256" (without quote)
+
 disabled
   The "disabled" keyword starts the server in the "disabled" state. That means
   that it is marked down in maintenance mode, and no connection other than the

include/haproxy/server-t.h

@@ -397,6 +397,7 @@ struct server {
 
 		char *ciphers;			/* cipher suite to use if non-null */
 		char *ciphersuites;			/* TLS 1.3 cipher suite to use if non-null */
+		char *curves;                    /* TLS curves list */
 		int options;			/* ssl options */
 		int verify;			/* verify method (set of SSL_VERIFY_* flags) */
 		struct tls_version_filter methods;	/* ssl methods */

include/haproxy/ssl_sock-t.h

@@ -278,6 +278,7 @@ struct global_ssl {
 #endif
 #if defined(SSL_CTX_set1_curves_list)
 	char *listen_default_curves;
+	char *connect_default_curves;
 #endif
 #if defined(SSL_CTX_set1_sigalgs_list)
 	char *listen_default_sigalgs;

reg-tests/ssl/ssl_curves.vtc

@@ -60,10 +60,10 @@ haproxy h1 -conf {
         default_backend ssl-be
 
     backend ssl-be
-        server s1 "${tmpdir}/ssl1.sock" ssl verify none crt ${testdir}/client.ecdsa.pem force-tlsv12
+        server s1 "${tmpdir}/ssl1.sock" ssl verify none crt ${testdir}/client.ecdsa.pem force-tlsv12 curves P-256:P-384
 
     backend ssl-curves-be
-        server s1 "${tmpdir}/ssl2.sock" ssl verify none crt ${testdir}/client.ecdsa.pem force-tlsv12
+        server s1 "${tmpdir}/ssl2.sock" ssl verify none crt ${testdir}/client.ecdsa.pem force-tlsv12 curves P-384
 
     backend ssl-ecdhe-256-be
         server s1 "${tmpdir}/ssl-ecdhe-256.sock" ssl verify none crt ${testdir}/client.ecdsa.pem force-tlsv12

src/cfgparse-ssl.c

@@ -301,7 +301,7 @@ static int ssl_parse_global_curves(char **args, int section_type, struct proxy *
 				   char **err)
 {
 	char **target;
-	target = &global_ssl.listen_default_curves;
+	target = (args[0][12] == 'b') ? &global_ssl.listen_default_curves : &global_ssl.connect_default_curves;
 
 	if (too_many_args(1, args, err, NULL))
 		return -1;
@@ -1669,6 +1669,14 @@ static int ssl_sock_init_srv(struct server *s)
 	}
 #endif
 
+#if defined(SSL_CTX_set1_curves_list)
+	if (global_ssl.connect_default_curves && !s->ssl_ctx.curves) {
+		s->ssl_ctx.curves = strdup(global_ssl.connect_default_curves);
+		if (!s->ssl_ctx.curves)
+			return 1;
+	}
+#endif
+
 	return 0;
 }
 
@@ -1775,6 +1783,29 @@ static int srv_parse_crl_file(char **args, int *cur_arg, struct proxy *px, struc
 #endif
 }
 
+/* parse the "curves" server keyword */
+static int srv_parse_curves(char **args, int *cur_arg, struct proxy *px, struct server *newsrv, char **err)
+{
+#ifndef SSL_CTX_set1_curves_list
+	memprintf(err, "'%s' : library does not support setting curves list", args[*cur_arg]);
+	return ERR_ALERT | ERR_FATAL;
+#else
+	char *arg;
+
+	arg = args[*cur_arg + 1];
+	if (!*arg) {
+		memprintf(err, "'%s' : missing curves list", args[*cur_arg]);
+		return ERR_ALERT | ERR_FATAL;
+	}
+	newsrv->ssl_ctx.curves = strdup(arg);
+	if (!newsrv->ssl_ctx.curves) {
+		memprintf(err, "out of memory");
+		return ERR_ALERT | ERR_FATAL;
+	}
+	return 0;
+#endif
+}
+
 /* parse the "crt" server keyword */
 static int srv_parse_crt(char **args, int *cur_arg, struct proxy *px, struct server *newsrv, char **err)
 {
@@ -2250,6 +2281,7 @@ static struct srv_kw_list srv_kws = { "SSL", { }, {
 #endif
 	{ "client-sigalgs",          srv_parse_client_sigalgs,     1, 1, 1 }, /* signature algorithms */
 	{ "crl-file",                srv_parse_crl_file,           1, 1, 1 }, /* set certificate revocation list file use on server cert verify */
+	{ "curves",                  srv_parse_curves,             1, 1, 1 }, /* set TLS curves list */
 	{ "crt",                     srv_parse_crt,                1, 1, 1 }, /* set client certificate */
 	{ "force-sslv3",             srv_parse_tls_method_options, 0, 1, 1 }, /* force SSLv3 */
 	{ "force-tlsv10",            srv_parse_tls_method_options, 0, 1, 1 }, /* force TLSv10 */
@@ -2320,6 +2352,7 @@ static struct cfg_kw_list cfg_kws = {ILH, {
 	{ CFG_GLOBAL, "ssl-default-server-ciphers", ssl_parse_global_ciphers },
 #if defined(SSL_CTX_set1_curves_list)
 	{ CFG_GLOBAL, "ssl-default-bind-curves", ssl_parse_global_curves },
+	{ CFG_GLOBAL, "ssl-default-server-curves", ssl_parse_global_curves },
 #endif
 #if defined(SSL_CTX_set1_sigalgs_list)
 	{ CFG_GLOBAL, "ssl-default-bind-sigalgs", ssl_parse_global_sigalgs },

src/ssl_sock.c

@@ -5105,6 +5105,9 @@ static int ssl_sock_prepare_srv_ssl_ctx(const struct server *srv, SSL_CTX *ctx)
 #if defined(SSL_CTX_set1_client_sigalgs_list)
 	const char *conf_client_sigalgs = NULL;
 #endif
+#if defined(SSL_CTX_set1_curves_list)
+	const char *conf_curves = NULL;
+#endif
 
 	if (conf_ssl_methods->flags && (conf_ssl_methods->min || conf_ssl_methods->max))
 		ha_warning("no-sslv3/no-tlsv1x are ignored for this server. "
@@ -5264,6 +5267,17 @@ static int ssl_sock_prepare_srv_ssl_ctx(const struct server *srv, SSL_CTX *ctx)
 	}
 #endif
 
+#if defined(SSL_CTX_set1_curves_list)
+	conf_curves =  srv->ssl_ctx.curves;
+	if (conf_curves) {
+		if (!SSL_CTX_set1_curves_list(ctx, conf_curves)) {
+			ha_alert("Proxy '%s': unable to set SSL curves list to '%s' for server '%s'.\n",
+			         curproxy->id, conf_curves, srv->id);
+			cfgerr++;
+		}
+	}
+#endif /* defined(SSL_CTX_set1_curves_list) */
+
 	return cfgerr;
 }