Re: ip_build_xmit() skb_reserve() problem

[kuznet@xxxxxxxxxxxxx]

Hello!

> (dev->hard_header_len + 15) & ~15) bytes in the skb may be not the same
> device that actually transmits packet (netfilter may reroute packet to
> another device for instance).

This is problem of netfilter. If it wants to do such crap,
it should make it correctly at least.



>                        Thus dev->hard_header() can't really
> assume that there is enough space for hardware header in the skb.
> hard_header() should always check that there is sufficient space in
> headroom if it doesn't do this it's a bug.

Nope. Caller must reserve enough of space.

If netfilter does not check hard_header_len at packet head
rewriting packets, it is plain fatal bug.

Alexey