netdev - Re: [PATCH net-next v2] ipv4: Restore accept_local behaviour in fib_validate

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Date:	Fri, 22 Aug 2014 23:07:42 +0300 (EEST)
From:	Julian Anastasov <ja@....bg>
To:	Sébastien Barré 
	<sebastien.barre@...ouvain.be>
cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	Gregory Detal <gregory.detal@...ouvain.be>,
	Christoph Paasch <christoph.paasch@...ouvain.be>,
	Hannes Frederic Sowa <hannes@...hat.com>,
	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Subject: Re: [PATCH net-next v2] ipv4: Restore accept_local behaviour in
 fib_validate_source()


	Hello,

On Sun, 17 Aug 2014, Sébastien Barré wrote:

> Commit 7a9bc9b81a5b ("ipv4: Elide fib_validate_source() completely when possible.")
> introduced a short-circuit to avoid calling fib_validate_source when not
> needed. That change took rp_filter into account, but not accept_local.
> This resulted in a change of behaviour: with rp_filter and accept_local
> off, incoming packets with a local address in the source field should be
> dropped.
> 
> Here is how to reproduce the change pre/post 7a9bc9b81a5b commit:
> -configure the same IPv4 address on hosts A and B.
> -try to send an ARP request from B to A.
> -The ARP request will be dropped before that commit, but accepted and answered
> after that commit.
> 
> This adds a check for ACCEPT_LOCAL, to maintain full
> fib validation in case it is 0. We also leave __fib_validate_source() earlier
> when possible, based on the same check as fib_validate_source(), once the
> accept_local stuff is verified.

	I remember there was related change for docs,
may be commit c801e3cc1925e0 should be reverted ?

> Cc: Gregory Detal <gregory.detal@...ouvain.be>
> Cc: Christoph Paasch <christoph.paasch@...ouvain.be>
> Cc: Hannes Frederic Sowa <hannes@...hat.com>
> Cc: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
> Signed-off-by: Sébastien Barré <sebastien.barre@...ouvain.be>

Regards

--
Julian Anastasov <ja@....bg>