netdev - Re: [PATCH] l2tp: avoid checksum offload for fragmented packets

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: <1370270652.1918.14.camel@bwh-desktop.uk.level5networks.com>
Date:	Mon, 3 Jun 2013 15:44:12 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Tom Parkin <tparkin@...alix.com>
CC:	<netdev@...r.kernel.org>, <jchapman@...alix.com>
Subject: Re: [PATCH] l2tp: avoid checksum offload for fragmented packets

On Mon, 2013-06-03 at 08:49 +0100, Tom Parkin wrote:
> Hardware offload for UDP datagram checksum calculation doesn't work with
> fragmented IP packets -- the device will note the fragmentation and leave the
> UDP checksum well alone.
> 
> As such, if we expect the L2TP packet to be fragmented by the IP layer we need
> to perform the UDP checksum ourselves in software (ref: net/ipv4/udp.c).
>
> This change modifies the L2TP xmit path to fallback to software checksum
> calculation if the L2TP packet + IP header exceeds the tunnel device MTU.
[...]

Surely this should be done in the IP stack when fragmenting, not in any
particular client?

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

--
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