Re: Routing loops & TTL tracking with tunnel devices

From: Jason A. Donenfeld
Date: Fri Apr 29 2022 - 17:10:27 EST


Hi Eric,

On Fri, Apr 29, 2022 at 01:54:27PM -0700, Eric Dumazet wrote:
> > Anyway, it'd be nice if there were a free u8 somewhere in sk_buff that I
> > could use for tracking times through the stack. Other kernels have this
> > but afaict Linux still does not. I looked into trying to overload some
> > existing fields -- tstamp/skb_mstamp_ns or queue_mapping -- which I was
> > thinking might be totally unused on TX?
>
>
> if skbs are stored in some internal wireguard queue, can not you use
> skb->cb[],
>
> like many other layers do ?

This isn't for some internal wireguard queue. The packets get sent out
of udp_tunnel_xmit_skb(), so they leave wireguard's queues.

Jason