@@ -53,7 +53,7 @@ openvpn_SOURCES = \
crypto.c crypto.h crypto_backend.h \
crypto_openssl.c crypto_openssl.h \
crypto_mbedtls.c crypto_mbedtls.h \
- dco.h dco_internal.h \
+ dco.c dco.h dco_internal.h \
dco_linux.c dco_linux.h \
dhcp.c dhcp.h \
dns.c dns.h \
new file mode 100644
@@ -0,0 +1,189 @@
+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single TCP/UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2021-2022 Arne Schwabe <arne@rfc2549.org>
+ * Copyright (C) 2021-2022 Antonio Quartulli <a@unstable.cc>
+ * Copyright (C) 2021-2022 OpenVPN Inc <sales@openvpn.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program 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 General Public License
+ * along with this program (see the file COPYING included with this
+ * distribution); if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#if defined(ENABLE_DCO)
+
+#include "syshead.h"
+#include "dco.h"
+#include "networking.h"
+#include "options.h"
+#include "ssl_ncp.h"
+#include "tun.h"
+
+static bool
+dco_check_option_conflict_platform(int msglevel, const struct options *o)
+{
+#if defined(TARGET_LINUX)
+ /* if the device name is fixed, we need to check if an interface with this
+ * name already exists. IF it does, it must be a DCO interface, otherwise
+ * DCO has to be disabled in order to continue.
+ */
+ if (tun_name_is_fixed(o->dev))
+ {
+ char iftype[IFACE_TYPE_LEN_MAX];
+ /* we pass NULL as net_ctx because using DCO on Linux implies that we
+ * are using SITNL and the latter does not need any context. This way we
+ * don't need to have the net_ctx percolate all the way here
+ */
+ int ret = net_iface_type(NULL, o->dev, iftype);
+ if ((ret == 0) && (strcmp(iftype, "ovpn-dco") != 0))
+ {
+ msg(msglevel, "Interface %s exists and is non-DCO. Disabling data channel offload",
+ o->dev);
+ return false;
+ }
+ else if ((ret < 0) && (ret != -ENODEV))
+ {
+ msg(msglevel, "Cannot retrieve type of device %s: %s (%d)", o->dev,
+ strerror(-ret), ret);
+ }
+#endif /* if defined(TARGET_LINUX) */
+ return true;
+}
+
+static bool
+dco_check_option_conflict_ce(const struct connection_entry *ce, int msglevel)
+{
+ if (ce->fragment)
+ {
+ msg(msglevel, "Note: --fragment disables data channel offload.");
+ return false;
+ }
+
+ if (ce->http_proxy_options)
+ {
+ msg(msglevel, "Note: --http-proxy disables data channel offload.");
+ return false;
+ }
+
+ if (ce->socks_proxy_server)
+ {
+ msg(msglevel, "Note: --socks-proxy disables data channel offload.");
+ return false;
+ }
+
+ return true;
+}
+
+bool
+dco_check_option_conflict(int msglevel, const struct options *o)
+{
+ if (o->tuntap_options.disable_dco)
+ {
+ /* already disabled by --disable-dco, no need to print warnings */
+ return false;
+ }
+
+ if (!dco_available(msglevel))
+ {
+ return false;
+ }
+
+ if (!dco_check_option_conflict_platform(msglevel, o))
+ {
+ return false;
+ }
+
+ if (dev_type_enum(o->dev, o->dev_type) != DEV_TYPE_TUN)
+ {
+ msg(msglevel, "Note: dev-type not tun, disabling data channel offload.");
+ return false;
+ }
+
+ /* At this point the ciphers have already been normalised */
+ if (o->enable_ncp_fallback
+ && !tls_item_in_cipher_list(o->ciphername, DCO_SUPPORTED_CIPHERS))
+ {
+ msg(msglevel, "Note: --data-cipher-fallback with cipher '%s' "
+ "disables data channel offload.", o->ciphername);
+ return false;
+ }
+
+ if (o->connection_list)
+ {
+ const struct connection_list *l = o->connection_list;
+ for (int i = 0; i < l->len; ++i)
+ {
+ if (!dco_check_option_conflict_ce(l->array[i], msglevel))
+ {
+ return false;
+ }
+ }
+ }
+ else
+ {
+ if (!dco_check_option_conflict_ce(&o->ce, msglevel))
+ {
+ return false;
+ }
+ }
+
+ if (o->mode == MODE_SERVER && o->topology != TOP_SUBNET)
+ {
+ msg(msglevel, "Note: NOT using '--topology subnet' disables data channel offload.");
+ return false;
+ }
+
+#if defined(USE_COMP)
+ if (o->comp.alg != COMP_ALG_UNDEF)
+ {
+ msg(msglevel, "Note: Using compression disables data channel offload.");
+
+ if (o->mode == MODE_SERVER && !(o->comp.flags & COMP_F_MIGRATE))
+ {
+ /* We can end up here from the multi.c call, only print the
+ * note if it is not already enabled */
+ msg(msglevel, "Consider using the '--compress migrate' option.");
+ }
+ return false;
+ }
+#endif
+
+ struct gc_arena gc = gc_new();
+ char *tmp_ciphers = string_alloc(o->ncp_ciphers, &gc);
+ const char *token;
+ while ((token = strsep(&tmp_ciphers, ":")))
+ {
+ if (!tls_item_in_cipher_list(token, DCO_SUPPORTED_CIPHERS))
+ {
+ msg(msglevel, "Note: cipher '%s' in --data-ciphers is not supported "
+ "by ovpn-dco, disabling data channel offload.", token);
+ gc_free(&gc);
+ return false;
+ }
+ }
+ gc_free(&gc);
+
+ return true;
+}
+
+#endif /* defined(ENABLE_DCO) */
@@ -276,6 +276,7 @@
<ClCompile Include="crypto.c" />
<ClCompile Include="crypto_openssl.c" />
<ClCompile Include="cryptoapi.c" />
+ <ClCompile Include="dco.c" />
<ClCompile Include="dco_linux.c" />
<ClCompile Include="dhcp.c" />
<ClCompile Include="dns.c" />
@@ -36,6 +36,9 @@
<ClCompile Include="cryptoapi.c">
<Filter>Source Files</Filter>
</ClCompile>
+ <ClCompile Include="dco.c">
+ <Filter>Source Files</Filter>
+ </ClCompile>
<ClCompile Include="dco_linux.c">
<Filter>Source Files</Filter>
</ClCompile>
Signed-off-by: Antonio Quartulli <a@unstable.cc> --- Changes from v1: * add 'already existing device check' to dco_check_option_conflict_platform() so that DCO can be pre-emptively disabled if the following are true: - an iface with the same name as provided by the user exists - the iface is non-DCO src/openvpn/Makefile.am | 2 +- src/openvpn/dco.c | 189 ++++++++++++++++++++++++++++ src/openvpn/openvpn.vcxproj | 1 + src/openvpn/openvpn.vcxproj.filters | 3 + 4 files changed, 194 insertions(+), 1 deletion(-) create mode 100644 src/openvpn/dco.c