netdev - Re: [PATCH] cls_flow: Add tunnel support to the flow classifier

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Date:	Mon, 17 Oct 2011 08:40:23 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Dan Siemon <dan@...erfire.com>
Cc:	netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] cls_flow: Add tunnel support to the flow classifier

Le dimanche 16 octobre 2011 à 19:06 -0400, Dan Siemon a écrit :
> When used on an interface carrying tunneled traffic the flow classifier
> can't look into the tunnels so all of the traffic within the tunnel is
> treated as a single flow. This does not allow any type of intelligent
> queuing to occur. This patch adds new keys to the flow classifier which
> look inside the tunnel. Presently IP-IP, IP-IPv6, IPv6-IPv6 and IPv6-IP
> tunnels are supported.
> 
> If you are interested I have posted some background and experimental
> results at:
> http://www.coverfire.com/archives/2011/10/16/making-the-linux-flow-classifier-tunnel-aware/
> 
> The related iproute2 patch can be found at the above URL as well.
> 
> Signed-off-by: Dan Siemon <dan@...erfire.com>
> 

Hi Dan

You're adding a lot of code (omitting the diffstat :( ) for a specific
usage, yet GRE tunnels are not supported.

IPv6 part is also a bit limited : It assumes TCP/UDP headers are the
first ones. Maybe its time to use ipv6_skip_exthdr() ?

Note also that if we pull (with pskb_network_may_pull()) too many bytes,
we kill routing performance on paged frags devices, wich are now
becoming very common.

Adding tunnel support and deep packet inspection might require the use
of skb_header_pointer() wich does the copy of needed data without
requiring expensive reallocation of skb head.

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