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.
Signed-off-by: Arne Schwabe <a...@rfc2549.org>
---
doc/openvpn.8 | 2 ++
src/openvpn/init.c | 4 ++++
src/openvpn/openvpn.h | 1 +
src/openvpn/ssl.c | 4 +++-
src/openvpn/ssl_common.h | 1 +
5 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/doc/openvpn.8 b/doc/openvpn.8
index 457c2667..ae24b6c0 100644
--- a/doc/openvpn.8
+++ b/doc/openvpn.8
@@ -4392,6 +4392,8 @@ 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 0bdb0a9c..8f142311 100644
--- a/src/openvpn/init.c
+++ b/src/openvpn/init.c
@@ -623,6 +623,7 @@ save_ncp_options(struct context *c)
c->c1.ciphername = c->options.ciphername;
c->c1.authname = c->options.authname;
c->c1.keysize = c->options.keysize;
+ c->c1.ncp_ciphers = c->options.ncp_ciphers;
}
/* Restores NCP-negotiable options to original values */
@@ -632,6 +633,7 @@ restore_ncp_options(struct context *c)
c->options.ciphername = c->c1.ciphername;
c->options.authname = c->c1.authname;
c->options.keysize = c->c1.keysize;
+ c->options.ncp_ciphers = c->c1.ncp_ciphers;
}
void
@@ -2827,6 +2829,7 @@ 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 = c->c1.ncp_ciphers;
to.ncp_enabled = options->ncp_enabled;
to.transition_window = options->transition_window;
to.handshake_window = options->handshake_window;
@@ -4532,6 +4535,7 @@ inherit_context_child(struct context *dest,
dest->c1.ciphername = src->c1.ciphername;
dest->c1.authname = src->c1.authname;
dest->c1.keysize = src->c1.keysize;
+ dest->c1.ncp_ciphers = src->c1.ncp_ciphers;
/* inherit auth-token */
dest->c1.ks.auth_token_key = src->c1.ks.auth_token_key;
diff --git a/src/openvpn/openvpn.h b/src/openvpn/openvpn.h
index 900db7e1..9e46ad6c 100644
--- a/src/openvpn/openvpn.h
+++ b/src/openvpn/openvpn.h
@@ -209,6 +209,7 @@ struct context_1
const char *ciphername; /**< Data channel cipher from config file */
const char *authname; /**< Data channel auth from config file */
+ const char *ncp_ciphers; /**< NCP Ciphers */
int keysize; /**< Data channel keysize from config file */
#endif
};
diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index 4455ebb8..6ca5c79a 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 8dd08862..fb82f610 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;
--
2.22.0
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