[Openvpn-devel,1/2] dco: process DCO control packets

Message ID 20220224165557.22060-2-kprovost@netgate.com
State Awaiting Upstream
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  • [Openvpn-devel,1/2] dco: process DCO control packets
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Commit Message

Kristof Provost via Openvpn-devel Feb. 24, 2022, 4:55 p.m.
From: Kristof Provost <kp@FreeBSD.org>

If control packets come in through the DCO interface (i.e. via
dco_do_read()) we must process them through process_incoming_link().
This doesn't currently manifest, because Linux passes control packets
through the regular socket, not via the DCO netlink interface, but other
platforms will not.

Signed-off-by: Kristof Provost <kprovost@netgate.com>
---
 src/openvpn/forward.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Antonio Quartulli March 9, 2022, 8:35 a.m. | #1
Hi Kristof,

On 24/02/2022 17:55, Kristof Provost via Openvpn-devel wrote:
> From: Kristof Provost <kp@FreeBSD.org>
> 
> If control packets come in through the DCO interface (i.e. via
> dco_do_read()) we must process them through process_incoming_link().
> This doesn't currently manifest, because Linux passes control packets
> through the regular socket, not via the DCO netlink interface, but other
> platforms will not.

This is an interesting catch - actually also ovpn-dco on Linux is 
expected to send control packets over netlink.

However, due to a little glitch packets were still sent over the UDP 
socket (this is expected only for the initial handshake).

Once this bug has been fixed, I could see that indeed 
process_incoming_dco() wasn't operating as it should and this patch was 
required.

I have squashed a modified version of this patch directly in my dco 
branch as it is needed to make ovpn-dco work.

Thanks a lot!

Best Regards,

Patch

diff --git a/src/openvpn/forward.c b/src/openvpn/forward.c
index cd956cb3..c16f32fc 100644
--- a/src/openvpn/forward.c
+++ b/src/openvpn/forward.c
@@ -1104,8 +1104,16 @@  process_incoming_link(struct context *c)
 static void
 process_incoming_dco(struct context *c)
 {
+    struct link_socket_info *lsi = get_link_socket_info(c);
+
     msg(M_INFO, __func__);
     dco_do_read(&c->c1.tuntap->dco);
+
+    c->c2.buf = c->c1.tuntap->dco.dco_packet_in;
+    c->c2.from = lsi->lsa->actual;
+
+    process_incoming_link(c);
+    buf_init(&c->c1.tuntap->dco.dco_packet_in, 0);
 }
 
 /*