From: Lev Stipakov <l...@openvpn.net> Servers 2.4.0 - 2.4.4 support peer-id and AEAD ciphers, but only send DATA_V1 packets. With DCO enabled on the client, connection is established but not working.
This is because DCO driver(s) are unable to handle DATA_V1 packets and forwards them to userspace, where they silently disappear since crypto context is in DCO and not in userspace. Starting from 2.4.5 server sends DATA_V2 so problem doesn't happen. We cannot switch to non-DCO on the fly, so we log this and advice user to upgrade the server to 2.4.5 or newer. Github: fixes OpenVPN/openvpn#422 Change-Id: I8cb2cb083e3cdadf187b7874979d79af3974e759 Signed-off-by: Lev Stipakov <l...@openvpn.net> Acked-by: Gert Doering <g...@greenie.muc.de> --- This change was reviewed on Gerrit and approved by at least one developer. I request to merge it to release/2.6. Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/368 This mail reflects revision 3 of this Change. Acked-by according to Gerrit (reflected above): Gert Doering <g...@greenie.muc.de> diff --git a/src/openvpn/forward.c b/src/openvpn/forward.c index d8ad0d1..40f21bc 100644 --- a/src/openvpn/forward.c +++ b/src/openvpn/forward.c @@ -1047,6 +1047,24 @@ if (c->c2.tls_multi) { + uint8_t opcode = *BPTR(&c->c2.buf) >> P_OPCODE_SHIFT; + + /* + * If DCO is enabled, the kernel drivers require that the + * other end only sends P_DATA_V2 packets. V1 are unknown + * to kernel and passed to userland, but we cannot handle them + * either because crypto context is missing - so drop the packet. + * + * This can only happen with particular old (2.4.0-2.4.4) servers. + */ + if ((opcode == P_DATA_V1) && dco_enabled(&c->options)) + { + msg(D_LINK_ERRORS, + "Data Channel Offload doesn't support DATA_V1 packets. " + "Upgrade your server to 2.4.5 or newer."); + c->c2.buf.len = 0; + } + /* * If tls_pre_decrypt returns true, it means the incoming * packet was a good TLS control channel packet. If so, TLS code @@ -1057,9 +1075,8 @@ * will load crypto_options with the correct encryption key * and return false. */ - uint8_t opcode = *BPTR(&c->c2.buf) >> P_OPCODE_SHIFT; - if (tls_pre_decrypt(c->c2.tls_multi, &c->c2.from, &c->c2.buf, &co, - floated, &ad_start)) + if (tls_pre_decrypt(c->c2.tls_multi, &c->c2.from, &c->c2.buf, + &co, floated, &ad_start)) { /* Restore pre-NCP frame parameters */ if (is_hard_reset_method2(opcode)) _______________________________________________ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
