Subject: [PATCH RFC v2 0/13] vti4: prepare namespace and interfamily support.

From: Steffen Klassert <[email-masked]>
Date: Mon, 16 Dec 2013 10:18:35 +0100

This patchset prepares vti4 for proper namespace and interfamily support.

Currently the receive hook is in the middle of the decapsulation
process, some of the header pointers point still into the IPsec packet
others point already into the decapsulated packet. This makes it
very unflexible and proper namespace and interfamily support can't
be done as it is.

The patchset that implements an IPsec protocol multiplexer, so that vti
can register it's own receive path hooks. Further it makes the i_key
usable for vti and changes the vti4 code to do the following:

vti uses the IPsec protocol multiplexer to register it's
own receive side hooks for ESP, AH and IPCOMP.

Vti does the following on receive side:

1. Do an input policy check for the IPsec packet we received.
   This is required because this packet could be already
   processed by IPsec (tunnel in tunnel or a block policy
   is present), so an inbound policy check is needed.

2. Clean the skb to not leak informations on namespace
   transitions.

3. Mark the packet with the i_key. The policy and the state
   must match this key now. Policy and state belong to the vti
   namespace and policy enforcement is done at the further layers.

4. Call the generic xfrm layer to do decryption and decapsulation.

5. Wait for a callback from the xfrm layer to properly update
   the device statistics.

On transmit side:

1. Mark the packet with the o_key. The policy and the state
   must match this key now.

2. Do a xfrm_lookup on the original packet with the mark applied.

3. Check if we got an IPsec route.

4. Clean the skb to not leak informations on namespace
   transitions.

5. Attach the dst_enty we got from the xfrm_lookup to the skb.

6. Call dst_output to do the IPsec processing.

7. Do the device statistics.

Changes from v1:

- Rebased to current net-next.
- Fix a rcu lockdep complaint in xfrm protocol registration/deregistration.
- Fix usage of a ipv4 specific callback handler in generic code.
- Use skb_scrub_packet() to clear the skb in vti_rcv(), suggested by
  Nicolas Dichtel.
- Add support for IPCOMP.
- Support inter address family tunneling.

I'd take this into the ipsec-next tree after some testing if noone
has further suggestions or objections.

I have the ipv6 side ready too, this will be a separate patchset.
The ipv6 patchset has dependencies against the ipv4 patchset, so I
hold it back until we have got the ipv4 side merged.