From: David Miller <davem@davemloft.net>
To: sgrubb@redhat.com
Cc: hch@infradead.org, stephan.mueller@atsec.com, tytso@mit.edu,
jarod@redhat.com, levinsasha928@gmail.com,
linux-crypto@vger.kernel.org, mpm@selenic.com,
nhorman@redhat.com, herbert.xu@redhat.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] random: add blocking facility to urandom
Date: Thu, 08 Sep 2011 12:13:47 -0400 (EDT) [thread overview]
Message-ID: <20110908.121347.1753630996526838840.davem@davemloft.net> (raw)
In-Reply-To: <201109080748.27750.sgrubb@redhat.com>
From: Steve Grubb <sgrubb@redhat.com>
Date: Thu, 8 Sep 2011 07:48:27 -0400
> On Thursday, September 08, 2011 04:44:20 AM Christoph Hellwig wrote:
>> On Wed, Sep 07, 2011 at 11:27:12PM +0200, Stephan Mueller wrote:
>> > And exactly that is the concern from organizations like BSI. Their
>> > cryptographer's concern is that due to the volume of data that you can
>> > extract from /dev/urandom, you may find cycles or patterns that increase
>> > the probability to guess the next random value compared to brute force
>> > attack. Note, it is all about probabilities.
>>
>> So don't use /dev/urandom if you don't like the behaviour. Breaking all
>> existing application because of a certification is simply not an option.
>
> This patch does not _break_ all existing applications. If a system were under attack,
> they might pause momentarily, but they do not break. Please, try the patch and use a
> nice large number like 2000000 and see for yourself. Right now, everyone arguing about
> this breaking things have not tried it to see if in fact things do break and how they
> break if they do.
If the application holds a critical resource other threads want when it
blocks on /dev/urandom, then your change breaks things. I can come up
with more examples if you like.
Please get off this idea that you can just change the blocking behavior
for a file descriptor and nothing of consequence will happen.
When this happens in the networking due to a bug or similar, we know
it does break things.
next prev parent reply other threads:[~2011-09-08 16:13 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-02 14:37 [PATCH] random: add blocking facility to urandom Jarod Wilson
2011-09-05 2:36 ` Sandy Harris
2011-09-06 14:09 ` Stephan Mueller
2011-09-07 17:38 ` Jarod Wilson
2011-09-07 18:12 ` Sasha Levin
2011-09-07 18:26 ` Jarod Wilson
2011-09-07 19:05 ` Sasha Levin
2011-09-07 19:30 ` Jarod Wilson
2011-09-07 20:00 ` Sasha Levin
2011-09-07 19:35 ` Neil Horman
2011-09-07 19:27 ` Ted Ts'o
2011-09-07 19:36 ` Jarod Wilson
2011-09-07 19:36 ` Jarod Wilson
2011-09-08 2:43 ` Sandy Harris
2011-09-07 19:49 ` David Miller
2011-09-07 20:02 ` Steve Grubb
2011-09-07 20:23 ` Sasha Levin
2011-09-07 20:30 ` Steve Grubb
2011-09-07 20:37 ` Sasha Levin
2011-09-07 20:56 ` Steve Grubb
2011-09-07 21:10 ` Sasha Levin
2011-09-07 21:28 ` Steve Grubb
2011-09-07 21:38 ` Sasha Levin
2011-09-07 21:35 ` Jarod Wilson
2011-09-07 21:43 ` Steve Grubb
2011-09-07 22:46 ` Sven-Haegar Koch
2011-09-08 7:21 ` Sasha Levin
2011-09-07 23:57 ` Neil Horman
2011-09-08 6:41 ` Tomas Mraz
2011-09-08 12:52 ` Neil Horman
2011-09-08 13:11 ` Steve Grubb
2011-09-08 13:49 ` Neil Horman
2011-09-09 2:21 ` Sandy Harris
2011-09-09 13:04 ` Steve Grubb
2011-09-09 16:25 ` Ted Ts'o
2011-09-09 21:27 ` Thomas Gleixner
2011-09-12 13:56 ` Jarod Wilson
2011-09-13 10:58 ` Peter Zijlstra
2011-09-13 12:18 ` Jarod Wilson
2011-09-11 2:05 ` Valdis.Kletnieks
2011-09-12 13:55 ` Jarod Wilson
2011-09-12 16:58 ` Valdis.Kletnieks
2011-09-12 18:26 ` Jarod Wilson
2011-09-07 20:33 ` Neil Horman
2011-09-07 20:48 ` Steve Grubb
2011-09-07 21:18 ` Ted Ts'o
2011-09-07 21:27 ` Stephan Mueller
2011-09-07 21:27 ` Stephan Mueller
2011-09-07 21:38 ` Ted Ts'o
2011-09-08 8:44 ` Christoph Hellwig
2011-09-08 11:48 ` Steve Grubb
2011-09-08 16:13 ` David Miller [this message]
2011-09-09 19:08 ` Eric Paris
2011-09-09 19:12 ` Neil Horman
2011-09-08 8:42 ` Christoph Hellwig
2011-09-08 8:42 ` Christoph Hellwig
2011-09-07 21:20 ` Nikos Mavrogiannopoulos
2011-09-08 8:41 ` Christoph Hellwig
2011-09-12 14:02 ` Jarod Wilson
2011-09-12 14:02 ` Jarod Wilson
2011-09-12 14:58 ` Neil Horman
2011-09-12 17:06 ` Mark Brown
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