From: Jeff Garzik <jeff@garzik.org>
To: Matt Mackall <mpm@selenic.com>
Cc: Sven-Haegar Koch <haegar@sdinet.de>,
Robin Getz <rgetz@blackfin.uclinux.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Chris Peterson <cpeterso@cpeterso.com>
Subject: Re: IRQF_SAMPLE_RANDOM question...
Date: Mon, 06 Apr 2009 20:30:59 -0400 [thread overview]
Message-ID: <49DA9EC3.4060903@garzik.org> (raw)
In-Reply-To: <1239063404.14392.118.camel@calx>
Matt Mackall wrote:
> On Tue, 2009-04-07 at 00:09 +0200, Sven-Haegar Koch wrote:
>> On Mon, 6 Apr 2009, Matt Mackall wrote:
>>
>>> On Mon, 2009-04-06 at 14:30 -0400, Robin Getz wrote:
>>>> We have lots of embedded headless systems (no keyboard/mouse, no soundcard, no
>>>> video) systems with *no* sources of entropy - and people using SSL.
>>> I'd rather add a random_sample_network call somewhere reasonably central
>>> in the network stack. Then we can use the knowledge that the sample is
>>> network-connected in the random core to decide how to measure its
>>> entropy. The trouble with IRQF_SAMPLE_RANDOM is that many of its users
>>> are technically bogus as entropy sources in the current model.
>>>
>>> I'm eventually going to move the RNG away from the strict theoretical
>>> entropy accounting model to a more pragmatic one which will be much
>>> happier with iffy entropy sources, but that's a ways off.
>> Btw, perhaps not the perfect question in this thread:
>> But what should we use to keep servers running without a hardware rng
>> available and without any external input besides the network?
>> After having ssh and openvpn die because of no random and having
>> the machines like dead and unreachable for me I use "ln -sf
>> /dev/urandom /dev/random", but that does not feel so good.
>
> It's fine so long as you're not wearing a tinfoil hat. In fact, as
> the /dev/random maintainer, I'd recommend it.
>
> Ted and I have recently been talking about revisiting the design
> of /dev/random to avoid these sorts of issues.
Two points...
- while I would welcome a more pragmatic entropy accounting model,
- it seems misplaced to _solely_ address network entropy problems
(timer-based regularity, external visibility and access) within the
devrandom machinery.
IRQF_SAMPLE_RANDOM in network drivers IMO just gives users a false sense
of security about their entropy.
And more fundamentally, IRQF_SAMPLE_RANDOM should never be used on a
non-random source.
Jeff
next prev parent reply other threads:[~2009-04-07 0:31 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-06 18:30 IRQF_SAMPLE_RANDOM question Robin Getz
2009-04-06 18:40 ` Jeff Garzik
2009-04-06 18:44 ` Stephen Hemminger
2009-04-06 18:49 ` Jeff Garzik
2009-04-07 8:27 ` Jeremy Fitzhardinge
2009-04-06 19:22 ` Robin Getz
2009-04-06 19:00 ` Alan Cox
2009-04-06 19:01 ` Matt Mackall
2009-04-06 22:09 ` Sven-Haegar Koch
2009-04-06 23:35 ` Jeff Garzik
2009-04-07 21:58 ` Robin Getz
2009-04-07 22:25 ` Jeff Garzik
2009-04-07 0:16 ` Matt Mackall
2009-04-07 0:30 ` Jeff Garzik [this message]
2009-04-07 11:16 ` Robin Getz
2009-04-07 14:57 ` Matt Mackall
2009-04-07 21:39 ` Chris Peterson
2009-04-07 22:30 ` Robin Getz
2009-04-08 21:53 ` Gilles Espinasse
2009-04-08 23:16 ` Chris Friesen
2009-04-09 4:24 ` Robin Getz
2009-04-07 21:44 ` Robin Getz
2009-04-08 19:51 ` Matt Mackall
2009-04-09 13:54 ` Robin Getz
2009-04-09 17:00 ` Matt Mackall
2009-04-10 0:41 ` Robin Getz
2009-04-10 1:29 ` Chris Peterson
2009-04-10 2:27 ` Matt Mackall
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