Re: [PATCH] ipv6_tunnel: Allow receiving packets on the fallback tunnel if they pass sanity checks

[David Miller <davem@davemloft.net>]

From: Phil Dibowitz <phil@ipom.com>
Date: Thu, 28 Jun 2012 21:15:52 -0700

> From: Ville Nuorvala <ville.nuorvala@gmail.com>
> 
> At Facebook, we do Layer-3 DSR via IP-in-IP tunneling. Our load balancers wrap
> an extra IP header on incoming packets so they can be routed to the backend.
> In the v4 tunnel driver, when these packets fall on the default tunl0 device,
> the behavior is to decapsulate them and drop them back on the stack. So our
> setup is that tunl0 has the VIP and eth0 has (obviously) the backend's real
> address.
> 
> In IPv6 we do the same thing, but the v6 tunnel driver didn't have this same
> behavior - if you didn't have an explicit tunnel setup, it would drop the
> packet.
> 
> This patch brings that v4 feature to the v6 driver.
> 
> The same IPv6 address checks are performed as with any normal tunnel,
> but as the fallback tunnel endpoint addresses are unspecified, the checks
> must be performed on a per-packet basis, rather than at tunnel
> configuration time.
> 
> [Patch description modified by phil@ipom.com]
> 
> Signed-off-by: Ville Nuorvala <ville.nuorvala@gmail.com>
> Tested-by: Phil Dibowitz <phil@ipom.com>

Applied to net-next