talons

commit b130471c6066581ae882fa049603e2e3567585c7
parent 49e55fb57409d81e8091c881cf47deb23777a423
Author: Andrej Kacian <ticho@claws-mail.org>
Date:   Fri,  2 Sep 2016 11:22:50 +0200

Be more strict about minimum DH prime size for TLS connections.

Since GnuTLS 3.1.7, this minimum size is dictated by the
priority string, and current (GnuTLS 3.3.0) "safe-enough"
value is 1008 bits. We set this minimum size explicitly
for older GnuTLS versions.

Users who are affected by this (their servers use DH prime
smaller than 1008 bits can override this by using priority
string starting with the keyword "LEGACY". This keyword
only works with GnuTLS 3.3.0 or newer, however.

Diffstat:
M
src/common/ssl.c
 | 
7
++++++-

1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/src/common/ssl.c b/src/common/ssl.c
@@ -364,7 +364,12 @@ gboolean ssl_init_socket(SockInfo *sockinfo)
 	gnutls_certificate_set_retrieve_function(xcred, gnutls_cert_cb);
 #endif
 
-	gnutls_dh_set_prime_bits(session, 512);
+#if GNUTLS_VERSION_NUMBER < 0x030107
+	/* Starting from GnuTLS 3.1.7, minimal size of the DH prime is
+	 * set by the priority string. By default ("NORMAL"), it is 1008
+	 * as of GnuTLS 3.3.0. */
+	gnutls_dh_set_prime_bits(session, 1008);
+#endif
 
 	if ((r = SSL_connect_nb(session)) < 0) {
 		g_warning("SSL connection failed (%s)", gnutls_strerror(r));