netdev - Re: Issue with gratuitous arps when new addr is different from cached addr

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20131121062635.GD4347@order.stressinduktion.org>
Date:	Thu, 21 Nov 2013 07:26:35 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Salam Noureddine <noureddine@...stanetworks.com>,
	"David S. Miller" <davem@...emloft.net>,
	Daniel Borkmann <dborkman@...hat.com>,
	Willem de Bruijn <willemb@...gle.com>,
	Phil Sutter <phil@....cc>, Eric Dumazet <edumazet@...gle.com>,
	netdev@...r.kernel.org
Subject: Re: Issue with gratuitous arps when new addr is different from cached addr

On Thu, Nov 21, 2013 at 07:23:49AM +0100, Hannes Frederic Sowa wrote:
> On Wed, Nov 20, 2013 at 10:06:34PM -0800, Salam Noureddine wrote:
> > Isn't locktime useful in that case for limiting the rate of garp
> > changes to the arp cache?
> 
> Yes, as I said, it would be nice to have rate-limiting for those, too.
> 
> GARP is used in cluster setups to make the switch-over as fast as possible and
> I don't think they accept those lock-down delays, so I guess it would be nice
> to forceful override the lladdr if (sip == tip) && ACCEPT_ARP(dev) is true in
> every case.
> 
> I guess you are not testing with ACCEPT_ARP?
> 
> In that case I am not sure what to do.
> 
> override = (...timing...) || sip == tip; could work but does relax the
> protection of the neigh cache.
> 
> In IPv6 we have a flag in the packet if we should overwrite the entry.
> 
> I'll have to think about that a bit more. Could well be the case that we need
> your proposal, too. But then we would have to validate the change with IPv6,
> too and neighbour cache states are really complex.

Hmm, could it help to bring the neighbor to suspect state (== WEAK_OVERRIDE)?

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html