gnutls_priority_set: do not override the version after handshake is complete

When an application would re-set priorities prior to a rehandshake
we would override the negotiated version with the highest supported,
something which may lead to issues. This disables that unnecessary
version override. See:

https://bugzilla.redhat.com/show_bug.cgi?id=1634736

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

2 files changed, 136 insertions, 1 deletions

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 9b7de3c512..4d40cc213a 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -157,7 +157,7 @@ ctests += mini-record-2 simple gnutls_hmac_fast set_pkcs12_cred cert certuniquei
 	 long-session-id mini-x509-callbacks-intr mini-dtls-lowmtu set_x509_key_file-late \
 	 crlverify mini-dtls-discard init_fds mini-record-failure \
 	 tls12-rehandshake-cert-2 custom-urls set_x509_key_mem set_x509_key_file \
-	 tls12-rehandshake-cert-auto \
+	 tls12-rehandshake-cert-auto tls12-rehandshake-set-prio \
 	 mini-chain-unsorted x509-verify-with-crl mini-dtls-mtu privkey-verify-broken \
 	 mini-dtls-record-asym key-import-export priority-set priority-set2 \
 	 pubkey-import-export sign-is-secure spki spki-abstract rsa-rsa-pss \
diff --git a/tests/tls12-rehandshake-set-prio.c b/tests/tls12-rehandshake-set-prio.c
new file mode 100644
index 0000000000..f33fd837de
--- /dev/null
+++ b/tests/tls12-rehandshake-set-prio.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2008-2012 Free Software Foundation, Inc.
+ * Copyright (C) 2018 Red Hat, Inc.
+ *
+ * Author: Simon Josefsson, Nikos Mavrogiannopoulos
+ *
+ * This file is part of GnuTLS.
+ *
+ * GnuTLS is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuTLS is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <gnutls/gnutls.h>
+
+#include "cert-common.h"
+#include "utils.h"
+#include "eagain-common.h"
+
+/* This program tests whether setting a new priority string
+ * with TLS1.3 enabled on a running TLS1.2 session will
+ * not prohibit or affect a following rehandshake.
+ *
+ * Seen in https://bugzilla.redhat.com/show_bug.cgi?id=1634736
+ */
+
+static void tls_log_func(int level, const char *str)
+{
+	fprintf(stderr, "<%d>| %s", level, str);
+}
+
+#define MAX_REHANDSHAKES 16
+
+static void test_rehandshake(void)
+{
+	/* Server stuff. */
+	gnutls_certificate_credentials_t serverx509cred;
+	gnutls_session_t server;
+	int sret = GNUTLS_E_AGAIN;
+	/* Client stuff. */
+	gnutls_certificate_credentials_t clientx509cred;
+	gnutls_session_t client;
+	int cret = GNUTLS_E_AGAIN;
+	unsigned i;
+
+	reset_buffers();
+	assert(gnutls_global_init()>=0);
+
+	gnutls_global_set_log_function(tls_log_func);
+
+	/* Init server */
+	assert(gnutls_certificate_allocate_credentials(&serverx509cred)>=0);
+
+	assert(gnutls_certificate_set_x509_key_mem(serverx509cred,
+						  &server_cert, &server_key,
+						  GNUTLS_X509_FMT_PEM)>=0);
+
+	assert(gnutls_init(&server, GNUTLS_SERVER)>=0);
+
+	assert(gnutls_credentials_set(server, GNUTLS_CRD_CERTIFICATE,
+				     serverx509cred)>=0);
+
+	assert(gnutls_priority_set_direct(server, "NORMAL:-VERS-TLS-ALL:+VERS-TLS1.1:+VERS-TLS1.2", NULL)>=0);
+
+	gnutls_transport_set_push_function(server, server_push);
+	gnutls_transport_set_pull_function(server, server_pull);
+	gnutls_transport_set_ptr(server, server);
+
+	/* Init client */
+	assert(gnutls_certificate_allocate_credentials(&clientx509cred)>=0);
+
+	assert(gnutls_init(&client, GNUTLS_CLIENT)>=0);
+
+	assert(gnutls_credentials_set(client, GNUTLS_CRD_CERTIFICATE,
+				     clientx509cred)>=0);
+
+	assert(gnutls_priority_set_direct(client, "NORMAL:-VERS-TLS-ALL:+VERS-TLS1.1:+VERS-TLS1.2", NULL)>=0);
+
+	gnutls_transport_set_push_function(client, client_push);
+	gnutls_transport_set_pull_function(client, client_pull);
+	gnutls_transport_set_ptr(client, client);
+
+	HANDSHAKE(client, server);
+
+	{
+		ssize_t n;
+		char b[1];
+
+		for (i=0;i<MAX_REHANDSHAKES;i++) {
+			sret = gnutls_rehandshake(server);
+
+			n = gnutls_record_recv(client, b, 1);
+			assert(n == GNUTLS_E_REHANDSHAKE);
+
+			/* includes TLS1.3 */
+			assert(gnutls_priority_set_direct(client, "NORMAL", NULL)>=0);
+
+			HANDSHAKE(client, server);
+		}
+	}
+
+	gnutls_bye(client, GNUTLS_SHUT_RDWR);
+	gnutls_bye(server, GNUTLS_SHUT_RDWR);
+
+	gnutls_deinit(client);
+	gnutls_deinit(server);
+
+	gnutls_certificate_free_credentials(serverx509cred);
+	gnutls_certificate_free_credentials(clientx509cred);
+
+	gnutls_global_deinit();
+}
+
+void doit(void)
+{
+	test_rehandshake();
+}