[PATCH 2.4.21-pre4] Propagate netfilter MARK value when tunneling

This patch enables the user to propagate netfilter MARK values from
tunneled packets to the tunnel packets. The primary use for this is QoS: it
enables you to MARK a packet before it enters a tunnel and then later pick
up the packet when it's about to leave the physical interface.

jamal [off-list ref] suggested to also propagate other skb specifics
like the tcindex and priority. I haven't included these in the current
patch for the very simple reason that I don't understand what they mean ;-)

The patch is currently limited to GRE, IPIP and SIT.

Patch is attached to this mail, but also can be downloaded from
http://dexter.hensema.net/~erik/patches/netfilter-propagate-mark-2.4.21-pre4.diff

-- 
Erik Hensema (erik@hensema.net)