netdev - Re: Aw: Re: question about checksumming and tcp

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] [day] [month] [year] [list]

Date:	Fri, 06 Nov 2015 11:32:56 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	ronny.hegewald@...ine.de
Cc:	Tom Herbert <tom@...bertland.com>, netdev@...r.kernel.org
Subject: Re: Aw: Re: question about checksumming and tcp_sendpage

On Fri, 2015-11-06 at 20:14 +0100, ronny.hegewald@...ine.de wrote:

> I think the checksum-building is not broken because of this on itself. The
> problem i see is for example in case pages are sent from a block-device 
> over the net. 
> 
> Depending on the block-device this pages might be changed at any time. 
> Because of the described issue the page-data wouldn't be copied as a call 
> to sock_no_sendpage would do it. So the page-data might change at any time
> during or after the checksum-building. From my understanding this would just
> cause a crc-error anytime after sending and would only lead to a resent 
> of the data, probably with a new checksum which will then be correct So
> there wouldn't be a obvious impact except some bad tcp packages.

We handle the case just fine.

grep for SKBTX_SHARED_FRAG

(successor of
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=cef401de7be8c4e155c6746bfccf721a4fa5fab
)




--
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