netdev - Re: [PATCH v6] vxlan: fix nonfunctional neigh

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Date:	Mon, 24 Mar 2014 15:35:42 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	dlstevens@...ibm.com
Cc:	shemminger@...tta.com, amwang@...hat.com, netdev@...r.kernel.org
Subject: Re: [PATCH v6] vxlan: fix nonfunctional neigh_reduce()

From: David L Stevens <dlstevens@...ibm.com>
Date: Mon, 24 Mar 2014 10:39:58 -0400

> 
> 	The VXLAN neigh_reduce() code is completely non-functional since
> check-in. Specific errors:
> 
> 1) The original code drops all packets with a multicast destination address,
> 	even though neighbor solicitations are sent to the solicited-node
> 	address, a multicast address. The code after this check was never run.
> 2) The neighbor table lookup used the IPv6 header destination, which is the
> 	solicited node address, rather than the target address from the
> 	neighbor solicitation. So neighbor lookups would always fail if it
> 	got this far. Also for L3MISSes.
> 3) The code calls ndisc_send_na(), which does a send on the tunnel device.
> 	The context for neigh_reduce() is the transmit path, vxlan_xmit(),
> 	where the host or a bridge-attached neighbor is trying to transmit
> 	a neighbor solicitation. To respond to it, the tunnel endpoint needs
> 	to do a *receive* of the appropriate neighbor advertisement. Doing a
> 	send, would only try to send the advertisement, encapsulated, to the
> 	remote destinations in the fdb -- hosts that definitely did not do the
> 	corresponding solicitation.
> 4) The code uses the tunnel endpoint IPv6 forwarding flag to determine the
> 	isrouter flag in the advertisement. This has nothing to do with whether
> 	or not the target is a router, and generally won't be set since the
> 	tunnel endpoint is bridging, not routing, traffic.
> 
> 	The patch below creates a proxy neighbor advertisement to respond to
> neighbor solicitions as intended, providing proper IPv6 support for neighbor
> reduction.
> 
> Signed-off-by: David L Stevens <dlstevens@...ibm.com>

Applied and queued up for -stable, thanks David.
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