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From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: fw@strlen.de, brouer@redhat.com, hans.schillstrom@ericsson.com,
	subramanian.vijay@gmail.com, dave.taht@gmail.com,
	netdev@vger.kernel.org, ncardwell@google.com,
	therbert@google.com, mph@hoth.dk
Subject: Re: [PATCH v2 net-next] tcp: avoid tx starvation by SYNACK packets
Date: Wed, 27 Jun 2012 15:23:53 -0700 (PDT)	[thread overview]
Message-ID: <20120627.152353.771450388391058676.davem@davemloft.net> (raw)
In-Reply-To: <1340833160.26242.176.camel@edumazet-glaptop>

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 27 Jun 2012 23:39:20 +0200

> On Wed, 2012-06-27 at 21:50 +0200, Florian Westphal wrote:
> 
>> I doubt using jhash is safe for syncookies.
>> 
>> There a several differences to other uses in kernel:
>> - all hash input except u32 cookie_secret[2] is known
>> - we transmit hash result (i.e, its visible to 3rd party)
>> - we do not re-seed the secret, ever
>> 
>> it should be quite easy to recompute cookie_secret[] from known syncookie
>> values?
> 
> We could re-seed the secrets every MSL seconds a bit like in
> tcp_cookie_generator()
> 
> This would require check_tcp_syn_cookie() doing two checks (most recent
> seed, and previous one if first check failed)

That could help, but I'm leaning towards not doing this at all.  Like
for the normal sequence number generation we really can't do this.

  reply	other threads:[~2012-06-27 22:23 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-31 21:56 [PATCH net-next] tcp: avoid tx starvation by SYNACK packets Eric Dumazet
2012-05-31 23:03 ` David Miller
2012-06-01  4:48   ` Eric Dumazet
2012-06-01 17:46     ` David Miller
2012-06-01  7:00 ` [PATCH] tcp: do not create inetpeer on SYNACK message Eric Dumazet
2012-06-01 18:24   ` David Miller
2012-06-01 21:34   ` Hans Schillström
2012-06-02  6:56     ` Eric Dumazet
2012-06-01  7:36 ` [PATCH net-next] tcp: avoid tx starvation by SYNACK packets Hans Schillstrom
2012-06-01  9:34   ` Eric Dumazet
2012-06-02  1:28 ` Dave Taht
2012-06-02  5:46   ` Eric Dumazet
2012-06-23  7:34     ` Vijay Subramanian
2012-06-23  8:42       ` [PATCH v2 " Eric Dumazet
2012-06-25  6:24         ` Hans Schillstrom
2012-06-25 22:43         ` David Miller
2012-06-26  4:51           ` Eric Dumazet
2012-06-26  4:55             ` David Miller
2012-06-26  5:34               ` Hans Schillstrom
2012-06-26  7:11                 ` David Miller
2012-06-26  7:27                   ` Hans Schillstrom
2012-06-26 17:02                 ` Eric Dumazet
2012-06-27  5:23                   ` Hans Schillstrom
2012-06-27  8:22                     ` David Miller
2012-06-27  8:25                       ` Jesper Dangaard Brouer
2012-06-27  8:30                       ` Hans Schillstrom
2012-06-27  8:40                       ` Eric Dumazet
2012-06-27  8:48                         ` David Miller
2012-06-27  6:32                   ` Jesper Dangaard Brouer
2012-06-27  6:54                     ` David Miller
2012-06-27  7:24                       ` Jesper Dangaard Brouer
2012-06-27  7:30                         ` Eric Dumazet
2012-06-27  7:54                           ` Jesper Dangaard Brouer
2012-06-27  8:02                             ` Eric Dumazet
2012-06-27  8:21                               ` Jesper Dangaard Brouer
2012-06-27  8:45                                 ` Eric Dumazet
2012-06-27  9:23                                   ` Jesper Dangaard Brouer
2012-06-27  8:13                           ` David Miller
2012-06-27 19:50                       ` Florian Westphal
2012-06-27 21:39                         ` Eric Dumazet
2012-06-27 22:23                           ` David Miller [this message]
2012-06-27 22:23                         ` David Miller

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