netdev - Re: [PATCH v2 nf-next] netfilter: conntrack: remove the central spinlock

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: <20130527143346.2d19e854@redhat.com>
Date:	Mon, 27 May 2013 14:33:46 +0200
From:	Jesper Dangaard Brouer <jbrouer@...hat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Pablo Neira Ayuso <pablo@...filter.org>,
	netfilter-devel@...r.kernel.org, netdev <netdev@...r.kernel.org>,
	Tom Herbert <therbert@...gle.com>,
	Patrick McHardy <kaber@...sh.net>
Subject: Re: [PATCH v2 nf-next] netfilter: conntrack: remove the central
 spinlock

On Fri, 24 May 2013 06:51:36 -0700
Eric Dumazet <eric.dumazet@...il.com> wrote:

> On Fri, 2013-05-24 at 15:16 +0200, Jesper Dangaard Brouer wrote:
[...cut...]
> > I'm amazed, this patch will actually make it a viable choice to load
> > the conntrack modules on a DDoS based filtering box, and use the
> > conntracks to protect against ACK and SYN+ACK attacks.
> > 
> > Simply by not accepting the ACK or SYN+ACK to create a conntrack
> > entry. Via the command:
> >  sysctl -w net/netfilter/nf_conntrack_tcp_loose=0
> > 
> > A quick test show; now I can run a LISTEN process on the port, and
> > handle an SYN+ACK attack of approx 2580Kpps (and the same for ACK
> > attacks), while running a LISTEN process on the port.
> > 
[...]
> > 
> 
> Wow, this is very interesting !
> 
> Did you test the thing when expectations are possible ? (say ftp
> module loaded)

Nope. I'm not sure how to create a test case, that causes an
expectation to be created.

> I think we should add RCU in the fast path, instead of having to lock
> the expectation lock. Its totally doable.

Interesting! :-)

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer
--
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