netdev - Re: problems with SCTP GSO

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]

Message-ID: <20180612173049.GA3732@localhost.localdomain>
Date:   Tue, 12 Jun 2018 14:30:50 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     lucien.xin@...il.com, edumazet@...gle.com, netdev@...r.kernel.org
Subject: Re: problems with SCTP GSO

On Tue, Jun 12, 2018 at 02:05:06PM -0300, Marcelo Ricardo Leitner wrote:
> On Mon, Jun 11, 2018 at 08:29:05PM -0700, David Miller wrote:
> > 
> > I would like to bring up some problems with the current GSO
> > implementation in SCTP.
> > 
> > The most important for me right now is that SCTP uses
> > "skb_gro_receive()" to build "GSO" frames :-(
> > 
> > Really it just ends up using the slow path (basically, label 'merge'
> > and onwards).
> > 
> > So, using a GRO helper to build GSO packets is not great.
> 
> Okay.
> 
> > 
> > I want to make major surgery here and the only way I can is if
> > it is exactly the GRO demuxing path that uses skb_gro_receive().
> > 
> > Those paths pass in the list head from the NAPI struct that initiated
> > the GRO code paths.  That makes it easy for me to change this to use a
> > list_head or a hash chain.
> > 
> > Probably in the short term SCTP should just have a private helper that
> > builds the frag list, appending 'skb' to 'head'.
> > 
> > In the long term, SCTP should use the page frags just like TCP to
> > append the data when building GSO frames.  Then it could actually be
> > offloaded and passed into drivers without linearizing.
> 
> Sounds like a plan. Shouldn't be too hard to do it.
> (I'm out on PTO, btw)

Xin will work on this, mean while at least. Thanks Xin.

> 
> Thanks,
> Marcelo
>