Wireguard uses incorrect interface - routing issue

[Stephan von Krawczynski]

On Fri, 21 Jun 2024 14:29:26 +0200
Daniel Gröber <dxld at darkboxed.org> wrote:

> On Fri, Jun 21, 2024 at 01:24:47PM +0200, Nico Schottelius wrote:
> > 
> > p.s.: the route lookup looks correct on the machine, when selecting the
> > source IP:
> > 
> > [11:15] server141.place10:~# ip r get 194.187.90.23
> > 194.187.90.23 via inet6 fe80::3eec:efff:fecb:d81a dev eth0 src
> > 192.168.1.149 uid 0 cache 
> > [11:16] server141.place10:~# ip r get 194.187.90.23 from 192.168.1.149
> > 194.187.90.23 from 192.168.1.149 via 192.168.1.254 dev eth1 table 42 uid 0 
> >     cache 
> > 
> > wireguard still uses the wrong interface:
> > 
> > 11:20:13.115154 eth0  Out IP 192.168.1.149.60031 > 194.187.90.23.4000:
> > UDP, length 148  
> 
> I haven't looked at the details yet but this smells like the same route
> caching issue I found a while ago:
> https://lists.zx2c4.com/pipermail/wireguard/2023-July/008111.html
> 
> Does up/down'ing the interface make the problem go away? IIRC that will
> re-initialize the udp socket and thus clear the route chache.
> 
> FYI Nico: It may be time to escalate these bugs to the network subsystem
> maintainers on netdev at vger.kernel.org since Jason is not reading this list
> anymore AFAICT.
> 
> get_maintainer.pl spits out this list of emails to send To:
> 
>     Jason A. Donenfeld" <Jason at zx2c4.com>,
>     "David S. Miller" <davem at davemloft.net>,
>     Eric Dumazet <edumazet at google.com>, 
>     Jakub Kicinski <kuba at kernel.org>,
>     Paolo Abeni <pabeni at redhat.com>,
>     wireguard at lists.zx2c4.com, 
>     netdev at vger.kernel.org,
>     linux-kernel at vger.kernel.org
> 
> Do add me to CC as well. Before sending I'd recommend working out an
> ip-netns based reproducer script -- makes it harder to ignore the report as
> "ugh, too much work" ;)
> 
> Let me know if you need help with that,
> --Daniel

... and in case you do find someone interested at all there is still the
problem of no signaling to anyone when a client connects.
I hardly can remember the decade when all this was implemented in cipe.

-- 
Regards,
Stephan