netdev - Re: [PATCH 07/10] net: remove NETIF_F_NO

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]

Date:	Thu, 14 Jul 2011 23:00:21 +0200
From:	Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:	Ben Hutchings <bhutchings@...arflare.com>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH 07/10] net: remove NETIF_F_NO_CSUM feature

On Thu, Jul 14, 2011 at 01:23:29AM +0100, Ben Hutchings wrote:
> On Thu, 2011-07-14 at 02:10 +0200, Michał Mirosław wrote:
> > There are no explicit users, so this is now equivalent to NETIF_F_HW_CSUM.
> [...]
> I think this is still a useful distinction, even the networking core
> currently doesn't care about the difference.

The problem is that all packets now can be redirected from NO_CSUM device
to other (or userspace). If some protocols just ignore checksum marking
altogether (like SCTP was doing) because of this flag, you get broken
packets that are hard to debug. It costs little to stay on the safe side
and calculate this additional u32 with checksum information, even if it
stays unused most of the time.

That's why I propose to remove NO_CSUM flag - to prevent someone to write
such a quietly broken code in the future.

Best Regards,
Michał Mirosław
--
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