Re: [PATCH net 0/2] udp: fix early demux for mcast packets

[David Miller <davem@davemloft.net>]

From: Paolo Abeni <pabeni@redhat.com>
Date: Thu, 28 Sep 2017 15:51:35 +0200

> Currently the early demux callbacks do not perform source address validation.
> This is not an issue for TCP or UDP unicast, where the early demux
> is only allowed for connected sockets and the source address is validated
> for the first packet and never change.
> 
> The UDP protocol currently allows early demux also for unconnected multicast
> sockets, and we are not currently doing any validation for them, after that
> the first packet lands on the socket: beyond ignoring the rp_filter - if 
> enabled - any kind of martian sources are also allowed.
> 
> This series addresses the issue allowing the early demux callback to return an
> error code, and performing the proper checks for unconnected UDP multicast
> sockets before leveraging the rx dst cache.
> 
> Alternatively we could disable the early demux for unconnected mcast sockets,
> but that would cause relevant performance regression - around 50% - while with
> this series, with full rp_filter in place, we keep the regression to a more 
> moderate level.

Series applied and queued up for -stable, thanks.