wireguard: problem sending via libpcap's packet socket

[Jason A. Donenfeld]

Hi Hans,

On Fri, Jun 26, 2020 at 2:14 PM Hans Wippel <ndev at hwipl.net> wrote:
> while toying around with sending packets with libpcap, I noticed that it
> did not work with a wireguard interface in contrast to my regular
> ethernet interface.

Thanks for letting me know. I'll try to repro and will look if this is
common behavior for all virtual drivers, or simply a bug in WireGuard
that I need to address.

If it is the latter, your patch below isn't quite correct; we'll
probably address this instead by simply setting skb->protocol in xmit
by peaking at the header, if skb->protocol is zero, and then keeping
the rest of the logic the same elsewhere.

Jason