RFC RFC: Caching IPv6 exthdr in skb->cb[]

Hi Patrick and Hans,

This is my followup to:
[PATCH 2/3] ipvs: Fix faulty IPv6 extension header handling in IPVS

Where you proposed improving the overall architecture of IPv6 extension header parsing not only for IPVS but for other related Netfilter subsystems as well.

We discussed using/extending inet6_skb_parm/IP6CB. There was not enough room for extending inet6_skb_parm directly, so I have introduced a struct inet6_skb_exthdr_cache/IP6CB_EXTHDR, which extend IP6CB.

The question is if this approach will work. Can netfilter be allowed to modify data after inet6_skb_parm/IP6CB, given all the different HOOKs ?

If we find this is a valid approach, then I'll update the IPVS patches to also use this.

This patchset is based upon:
Patrick's tree: git://github.com/kaber/nf-next-ipv6-nat.git

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Jesper Dangaard Brouer (2):
netfilter: More users of ipv6_find_hdr_cb()
net: Cache IPv6 extension header "skip" parsing

 include/linux/ipv6.h                      |   15 +++++++++++
 include/linux/netfilter_ipv6/ip6_tables.h |   40 +++++++++++++++++++++++++++++
 net/ipv6/netfilter/ip6_tables.c           |    2 +
 net/netfilter/xt_TPROXY.c                 |    2 +
 net/netfilter/xt_socket.c                 |    2 +
 5 files changed, 58 insertions(+), 3 deletions(-)

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Best regards,
Jesper Dangaard Brouer
MSc.CS, Sr. Network Kernel Developer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer