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From: "David Laight" <David.Laight@ACULAB.COM>
To: "Jesper Dangaard Brouer" <brouer@redhat.com>,
	"Eric Dumazet" <eric.dumazet@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	"Hannes Frederic Sowa" <hannes@stressinduktion.org>,
	<netdev@vger.kernel.org>
Subject: RE: [net-next PATCH 1/4] Revert "inet: limit length of fragment queue hash table bucket lists"
Date: Thu, 25 Apr 2013 14:58:54 +0100	[thread overview]
Message-ID: <AE90C24D6B3A694183C094C60CF0A2F6026B7202@saturn3.aculab.com> (raw)
In-Reply-To: <1366895438.26911.572.camel@localhost>

> The reason this is inevitable, is the attackers invalid fragments will
> never finish (timeout 30 sec), while valid fragments will complete and
> "exit" the queue, thus the end result is hash bucket is filled with
> attackers invalid/incomplete fragments.  IMHO this is a very dangerous
> "feature" to support.

If you are being attacked, the hash buckets will immediately
be filled with invalid packets, no valid packets will enter.
If you delete old entries to add new ones then any valid
packet will soon be flushed out by invalid ones.
The only time you'll manage to assemble anything is if
the valid fragments arrive 'back to back'.

The only hope is to part-decode initial fragments and decide
whether they are valid.

	David



  reply	other threads:[~2013-04-25 14:00 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-24 15:47 [net-next PATCH 0/4] net: frag patchset for fixing LRU scalability issue Jesper Dangaard Brouer
2013-04-24 15:48 ` [net-next PATCH 1/4] Revert "inet: limit length of fragment queue hash table bucket lists" Jesper Dangaard Brouer
2013-04-25  0:00   ` Eric Dumazet
2013-04-25 13:10     ` Jesper Dangaard Brouer
2013-04-25 13:58       ` David Laight [this message]
2013-05-02  7:59     ` Jesper Dangaard Brouer
2013-05-02 15:16       ` Eric Dumazet
2013-05-03  9:15         ` Jesper Dangaard Brouer
2013-04-24 15:48 ` [net-next PATCH 2/4] net: increase frag hash size Jesper Dangaard Brouer
2013-04-24 22:09   ` Sergei Shtylyov
2013-04-25 10:13     ` Jesper Dangaard Brouer
2013-04-25 12:13       ` Sergei Shtylyov
2013-04-25 19:11       ` David Miller
2013-04-24 23:48   ` Eric Dumazet
2013-04-25  3:26   ` Hannes Frederic Sowa
2013-04-25 19:52   ` [net-next PATCH V2] " Jesper Dangaard Brouer
2013-04-29 17:44     ` David Miller
2013-04-24 15:48 ` [net-next PATCH 3/4] net: avoid false perf interpretations in frag code Jesper Dangaard Brouer
2013-04-24 23:48   ` Eric Dumazet
2013-04-24 23:54     ` David Miller
2013-04-25 10:57     ` Jesper Dangaard Brouer
2013-04-25 19:13       ` David Miller
2013-04-24 15:48 ` [net-next PATCH 4/4] net: frag LRU list per CPU Jesper Dangaard Brouer
2013-04-25  0:25   ` Eric Dumazet
2013-04-25  2:05     ` Eric Dumazet
2013-04-25 14:06       ` Jesper Dangaard Brouer
2013-04-25 14:37         ` Eric Dumazet
2013-04-25 13:59     ` Jesper Dangaard Brouer
2013-04-25 14:10       ` Eric Dumazet
2013-04-25 14:18       ` Eric Dumazet
2013-04-25 19:15         ` Jesper Dangaard Brouer
2013-04-25 19:22           ` Eric Dumazet
2013-04-24 16:21 ` [net-next PATCH 0/4] net: frag patchset for fixing LRU scalabilityissue David Laight
2013-04-25 11:39   ` Jesper Dangaard Brouer
2013-04-25 12:57     ` David Laight
2013-04-24 17:27 ` [net-next PATCH 0/4] net: frag patchset for fixing LRU scalability issue Hannes Frederic Sowa

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