From b5e4bf4b6c2d5a3ac46cce78d69673c224256206 Mon Sep 17 00:00:00 2001 From: Tobias Brunner Date: Thu, 5 Oct 2023 10:27:18 +0200 Subject: [PATCH] tls-server: Also change DH group when selecting a different EC curve If we initially selected a group the peer doesn't support (e.g. because curve25519 is the first ECDH group provided by plugins), then found a supported curve, we previously still instantiated a DH object for the original group and might have formatted the parameters incorrectly. --- src/libtls/tls_server.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/src/libtls/tls_server.c b/src/libtls/tls_server.c index e91e4e440..3ad9fd2a5 100644 --- a/src/libtls/tls_server.c +++ b/src/libtls/tls_server.c @@ -1483,20 +1483,23 @@ static status_t send_certificate_request(private_tls_server_t *this, } /** - * Try to find a curve supported by both, client and server + * Try to find a curve/group supported by both, client and server */ static bool find_supported_curve(private_tls_server_t *this, - tls_named_group_t *curve) + tls_named_group_t *curve, + key_exchange_method_t *group) { tls_named_group_t current; + key_exchange_method_t current_group; enumerator_t *enumerator; enumerator = this->crypto->create_ec_enumerator(this->crypto); - while (enumerator->enumerate(enumerator, NULL, ¤t)) + while (enumerator->enumerate(enumerator, ¤t_group, ¤t)) { if (peer_supports_curve(this, current)) { *curve = current; + *group = current_group; enumerator->destroy(enumerator); return TRUE; } @@ -1520,7 +1523,7 @@ static status_t send_server_key_exchange(private_tls_server_t *this, { curve = tls_ec_group_to_curve(group); if (!curve || (!peer_supports_curve(this, curve) && - !find_supported_curve(this, &curve))) + !find_supported_curve(this, &curve, &group))) { DBG1(DBG_TLS, "no EC group supported by client and server"); this->alert->add(this->alert, TLS_FATAL, TLS_HANDSHAKE_FAILURE);