netdev - Re: [PATCH V3 net-next] ixgbe: Avoid unaligned access in ixgbe

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Date:	Wed, 16 Mar 2016 15:58:52 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	Sowmini Varadhan <sowmini.varadhan@...cle.com>,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
	alexander.duyck@...il.com
Cc:	jesse.brandeburg@...el.com, shannon.nelson@...el.com,
	carolyn.wyborny@...el.com, donald.c.skidmore@...el.com,
	bruce.w.allan@...el.com, john.ronciak@...el.com,
	mitch.a.williams@...el.com
Subject: Re: [PATCH V3 net-next] ixgbe: Avoid unaligned access in
 ixgbe_atr() for LLC packets

On Mon, 2016-03-14 at 15:47 -0400, Sowmini Varadhan wrote:
> 
> For LLC based protocols like lldp, stp etc., the ethernet header
> is an 802.3 header with a h_proto that is not 0x800, 0x86dd, or
> even 0x806.  In this world, the skb_network_header() points at
> the DSAP/SSAP/..  and is not likely to be NET_IP_ALIGNed in
> ixgbe_atr().
> 
> With LLC, drivers are not likely to correctly find IPVERSION,
> or "6", at hdr.ipv4->version, but will instead just needlessly
> trigger an unaligned access. (IPv4/IPv6 over LLC is almost never
> implemented).
> 
> The unaligned access is thus avoidable: bail out quickly after
> examining skb->protocol. The only Ethernet II protocols handled
> are IPv4 and IPv6
> 
> Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
> ---
> v2: Alexander Duyck comments
> v3: filter out all ethertypes  except for Ethernet II and (IPv4 or
> IPv6)
> 
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)

This does not apply since Alex Duyck beat you to the fix.  Here is the
patch he submitted on 3/15 which corrects the issue.  So I am dropping
your patch from the queue.

commit 04b8b51c34837765cf6250f69d419c439dc393bf
Author: Alexander Duyck <aduyck@...antis.com>
Date:   Tue Mar 15 15:10:22 2016 -0700

    ixgbe: Fix ATR so that it correctly handles IPv6 extension headers

    The ATR code was assuming that it would be able to use tcp_hdr for
    every TCP frame that came through.  However this isn't the case as
it
    is possible for a frame to arrive that is TCP but sent through
something
    like a raw socket.  As a result the driver was setting up bad
filters in
    which tcp_hdr was really pointing to the network header so the data
was
    all invalid.

    In order to correct this I have added a bit of parsing logic that
will
    determine the TCP header location based off of the network header
and
    either the offset in the case of the IPv4 header, or a walk through
the
    IPv6 extension headers until it encounters the header that
indicates
    IPPROTO_TCP.  In addition I have added checks to verify that the
lowest
    protocol provided is recognized as IPv4 or IPv6 to help mitigate
raw
    sockets using ETH_P_ALL from having ATR applied to them.

    Signed-off-by: Alexander Duyck <aduyck@...antis.com>
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