From: Arne Schwabe Date: Mon, 17 Feb 2020 14:43:35 +0000 (+0100) Subject: Only announce IV_NCP=2 when we are willing to support these ciphers X-Git-Tag: v2.5_beta1~209 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=868b200c3aef6ee5acfdf679770832018ebc7b70;p=thirdparty%2Fopenvpn.git Only announce IV_NCP=2 when we are willing to support these ciphers We currently always announce IV_NCP=2 when we support these ciphers even when we do not accept them. This lead to a server pushing a AES-GCM-128 cipher to clients and the client then rejecting it. Patch V2: Remove unecessary restoring of ncp_ciphers Patch V3: Do not add ncp_ciphers in context Signed-off-by: Arne Schwabe Acked-by: Lev Stipakov Message-Id: <20200217144339.3273-2-arne@rfc2549.org> URL: https://www.mail-archive.com/search?l=mid&q=20200217144339.3273-2-arne@rfc2549.org Signed-off-by: Gert Doering --- diff --git a/doc/openvpn.8 b/doc/openvpn.8 index 8feb3b9ce..b8f2f0424 100644 --- a/doc/openvpn.8 +++ b/doc/openvpn.8 @@ -4398,6 +4398,8 @@ NCP server (v2.4+) with "\-\-cipher BF\-CBC" and "\-\-ncp\-ciphers AES\-256\-GCM:AES\-256\-CBC" set can either specify "\-\-cipher BF\-CBC" or "\-\-cipher AES\-256\-CBC" and both will work. +Note, for using NCP with a OpenVPN 2.4 server this list must include +the AES\-256\-GCM and AES\-128\-GCM ciphers. .\"********************************************************* .TP .B \-\-ncp\-disable diff --git a/src/openvpn/init.c b/src/openvpn/init.c index 04207b61c..5c2f801a3 100644 --- a/src/openvpn/init.c +++ b/src/openvpn/init.c @@ -2827,6 +2827,7 @@ do_init_crypto_tls(struct context *c, const unsigned int flags) to.tcp_mode = link_socket_proto_connection_oriented(options->ce.proto); to.config_ciphername = c->c1.ciphername; to.config_authname = c->c1.authname; + to.config_ncp_ciphers = options->ncp_ciphers; to.ncp_enabled = options->ncp_enabled; to.transition_window = options->transition_window; to.handshake_window = options->handshake_window; diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c index e708fc939..b83517376 100644 --- a/src/openvpn/ssl.c +++ b/src/openvpn/ssl.c @@ -2322,7 +2322,9 @@ push_peer_info(struct buffer *buf, struct tls_session *session) /* support for Negotiable Crypto Parameters */ if (session->opt->ncp_enabled - && (session->opt->mode == MODE_SERVER || session->opt->pull)) + && (session->opt->mode == MODE_SERVER || session->opt->pull) + && tls_item_in_cipher_list("AES-128-GCM", session->opt->config_ncp_ciphers) + && tls_item_in_cipher_list("AES-256-GCM", session->opt->config_ncp_ciphers)) { buf_printf(&out, "IV_NCP=2\n"); } diff --git a/src/openvpn/ssl_common.h b/src/openvpn/ssl_common.h index 8dd08862d..fb82f6104 100644 --- a/src/openvpn/ssl_common.h +++ b/src/openvpn/ssl_common.h @@ -290,6 +290,7 @@ struct tls_options const char *config_ciphername; const char *config_authname; + const char *config_ncp_ciphers; bool ncp_enabled; bool tls_crypt_v2;