From: Patrick McHardy <kaber@trash.net>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Changli Gao <xiaosuo@gmail.com>,
hawk@comx.dk,
Linux Kernel Network Hackers <netdev@vger.kernel.org>,
netfilter-devel@vger.kernel.org,
Paul E McKenney <paulmck@linux.vnet.ibm.com>
Subject: Re: DDoS attack causing bad effect on conntrack searches
Date: Fri, 23 Apr 2010 12:56:57 +0200 [thread overview]
Message-ID: <4BD17CF9.4020502@trash.net> (raw)
In-Reply-To: <1271946961.7895.5665.camel@edumazet-laptop>
Eric Dumazet wrote:
> Le jeudi 22 avril 2010 à 15:17 +0200, Patrick McHardy a écrit :
>> Changli Gao wrote:
>>>> struct nf_conntrack_tuple_hash *
>>>> __nf_conntrack_find(struct net *net, const struct nf_conntrack_tuple *tuple)
>>>> ...
>>> We should add a retry limit there.
>> We can't do that since that would allow false negatives.
>
> If one hash slot is under attack, then there is a bug somewhere.
>
> If we cannot avoid this, we can fallback to a secure mode at the second
> retry, and take the spinlock.
>
> Tis way, most of lookups stay lockless (one pass), and some might take
> the slot lock to avoid the possibility of a loop.
That sounds like a good idea. But lets what for Jesper's test results
before we start fixing this problem :)
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next prev parent reply other threads:[~2010-04-23 10:56 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-22 12:58 DDoS attack causing bad effect on conntrack searches Jesper Dangaard Brouer
2010-04-22 13:13 ` Changli Gao
2010-04-22 13:17 ` Patrick McHardy
2010-04-22 14:36 ` Eric Dumazet
2010-04-22 14:53 ` Eric Dumazet
2010-04-22 15:51 ` Paul E. McKenney
2010-04-22 16:02 ` Eric Dumazet
2010-04-22 16:34 ` Paul E. McKenney
2010-04-22 20:38 ` Jesper Dangaard Brouer
2010-04-22 21:03 ` Eric Dumazet
2010-04-22 21:14 ` Eric Dumazet
2010-04-22 23:44 ` David Miller
2010-04-23 5:44 ` Eric Dumazet
2010-04-23 8:13 ` David Miller
2010-04-23 8:18 ` David Miller
2010-04-23 8:40 ` Jesper Dangaard Brouer
2010-04-23 10:36 ` Patrick McHardy
2010-04-23 11:06 ` Eric Dumazet
2010-04-22 21:28 ` Jesper Dangaard Brouer
2010-04-23 7:23 ` Jan Engelhardt
2010-04-23 7:46 ` Eric Dumazet
2010-04-23 7:55 ` Jan Engelhardt
2010-04-23 9:23 ` Eric Dumazet
2010-04-23 10:55 ` Patrick McHardy
2010-04-23 11:05 ` Eric Dumazet
2010-04-23 11:06 ` Patrick McHardy
2010-04-23 20:57 ` Eric Dumazet
2010-04-24 11:11 ` Jesper Dangaard Brouer
2010-04-24 20:11 ` Eric Dumazet
2010-04-26 14:36 ` Jesper Dangaard Brouer
2010-05-31 21:21 ` Eric Dumazet
2010-06-01 0:28 ` Changli Gao
2010-06-01 5:05 ` Eric Dumazet
2010-06-01 5:48 ` Changli Gao
2010-06-01 10:18 ` Patrick McHardy
2010-06-01 10:31 ` Eric Dumazet
2010-06-01 10:41 ` Patrick McHardy
2010-06-01 16:20 ` [RFC nf-next-2.6] conntrack: per cpu nf_conntrack_untracked Eric Dumazet
2010-06-04 11:40 ` Patrick McHardy
2010-06-04 12:10 ` Changli Gao
2010-06-04 12:29 ` Patrick McHardy
2010-06-04 12:36 ` Eric Dumazet
2010-06-04 16:25 ` [PATCH nf-next-2.6] conntrack: IPS_UNTRACKED bit Eric Dumazet
2010-06-04 20:15 ` [PATCH nf-next-2.6 2/2] conntrack: per_cpu untracking Eric Dumazet
2010-06-08 14:29 ` Patrick McHardy
2010-06-08 14:52 ` Eric Dumazet
2010-06-08 15:12 ` Eric Dumazet
2010-06-09 12:45 ` Patrick McHardy
2010-06-08 14:12 ` [PATCH nf-next-2.6] conntrack: IPS_UNTRACKED bit Patrick McHardy
2010-04-23 10:56 ` Patrick McHardy [this message]
2010-04-23 12:45 ` DDoS attack causing bad effect on conntrack searches Jesper Dangaard Brouer
2010-04-23 13:57 ` Patrick McHardy
2010-04-22 13:31 ` Jesper Dangaard Brouer
2010-04-23 10:35 ` Patrick McHardy
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