Re: [PATCH] Disable rp_filter for IPsec packets

[David Miller <davem@davemloft.net>]

From: Michael Smith <msmith@cbnco.com>
Date: Mon, 14 Mar 2011 18:11:24 -0400

> David Miller wrote:
>> I was trying to get you to think out of the box and come up with
>> something clever, but that isn't working. :-)
> 
> Yes, I got that, but I don't know what you are looking for, and don't
> expect to succeed by trying something else at random.

Existing arguments might be large enough to carry more than one piece
of information :-)

>> In short, fib_validate_source() is nothing but completely unnecessary
>> overhead in the common case.
> 
> I'm not entitled to an opinion about fib_validate_source(). It feels
> like it might be trying to do one too many things. If it were my code
> I might split the RPF out from the spec_dst calculation, move the
> whole lot into net/ipv4/route.c, and only do the fib_lookup() if RPF
> is enabled or CONFIG_IP_ROUTE_CLASSID (i.e. we need to know the itag).

Can't split two two things up, because spec_dst is a product of the
reverse FIB lookup, in the form of FIB_RES_PREFSRC().