netfilter: nft_payload: work around vlan header stripping
netfilter: nft_payload: work around vlan header stripping

make payload expression aware of the fact that VLAN offload may have
removed a vlan header.

When we encounter tagged skb, transparently insert the tag into the
register so that vlan header matching can work without userspace being
aware of offload features.

Signed-off-by: Florian Westphal <cef439e78636cdab99cd2923826c5065a0743e5b@strlen.de>
Signed-off-by: Pablo Neira Ayuso <707d14912bb250caf67dfe0ea4035681fbfc4f56@netfilter.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs