From: Ben Hutchings <bhutchings@solarflare•com>
To: Bill Fink <billfink@mindspring•com>
Cc: "Krzysztof Halasa" <khc@pm•waw.pl>,
"Alejandro Riveira Fernández" <ariveira@gmail•com>,
"Theodore Tso" <tytso@MIT•EDU>, "Glen Turner" <gdt@gdt•id.au>,
"Chris Peterson" <cpeterso@cpeterso•com>,
"Alan Cox" <alan@lxorguk•ukuu.org.uk>,
"Lennart Sorensen" <lsorense@csclub•uwaterloo.ca>,
"Jeff Garzik" <jeff@garzik•org>,
"Kok, Auke" <auke-jan.h.kok@intel•com>,
"Rick Jones" <rick.jones2@hp•com>,
"Brandeburg, Jesse" <jesse.brandeburg@intel•com>,
netdev@vger•kernel.org, linux-kernel@vger•kernel.org
Subject: Re: [PATCH] drivers/net: remove network drivers' last few uses of IRQF_SAMPLE_RANDOM
Date: Mon, 26 May 2008 23:11:21 +0100 [thread overview]
Message-ID: <20080526221119.GF28241@solarflare.com> (raw)
In-Reply-To: <20080526175227.4b7ae764.billfink@mindspring.com>
Bill Fink wrote:
> On Mon, 26 May 2008, Krzysztof Halasa wrote:
>
> > Bill Fink <billfink@mindspring•com> writes:
> >
> > > Another idea that occured to me: How about using the low order bits
> > > of the instruction memory address being executed that was interrupted
> > > by the HZ timer interrupt.
> >
> > Think of constant-instructions-length processors :-)
>
> I'm not sure what you're driving at, but if it's that you shouldn't
> use the very last 2 or 3 bits, then sure those should be excluded.
> But that still leaves 9 or 10 bits at least in the page offset, and
> that's being conservative in the number of address bits to sample.
We would still need to exclude any tight loops which an attacker could
predict or influence a process to enter - the idle loop obviously, plus
udelay(), memcpy() and probably many other functions. Some such loops may
be in userland and therefore unknown to us. So there might not be nearly
as many bits of entropy in the program counter as could be naively
expected. What's more, once userland is blocked on /dev/random, there is
no more entropy available from the program counter!
Ben.
--
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
next prev parent reply other threads:[~2008-05-26 22:12 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-15 7:11 [PATCH] drivers/net: remove network drivers' last few uses of IRQF_SAMPLE_RANDOM Chris Peterson
2008-05-15 13:21 ` Alan Cox
2008-05-15 16:07 ` Brandeburg, Jesse
2008-05-15 16:39 ` Alan Cox
2008-05-15 18:14 ` Jeff Garzik
2008-05-15 18:47 ` Kok, Auke
2008-05-15 19:10 ` Jeff Garzik
2008-05-15 18:50 ` Rick Jones
2008-05-15 19:11 ` Jeff Garzik
2008-05-15 19:55 ` [PATCH] " Jeff Garzik
2008-05-16 0:27 ` Andi Kleen
2008-05-16 9:56 ` Alan Cox
2008-05-16 10:19 ` Andi Kleen
2008-05-16 12:12 ` Herbert Xu
2008-05-16 16:25 ` Andi Kleen
2008-05-17 1:01 ` Herbert Xu
2008-05-17 10:59 ` Andi Kleen
2008-05-17 19:54 ` Chris Peterson
2008-05-17 20:05 ` Arjan van de Ven
2008-05-18 10:13 ` Andi Kleen
2008-05-18 11:26 ` Theodore Tso
2008-05-18 12:57 ` Joe Korty
2008-05-18 17:53 ` Andi Kleen
2008-05-25 15:26 ` Glen Turner
2008-05-19 12:29 ` Benny Amorsen
2008-05-18 10:08 ` Andi Kleen
2008-05-22 9:28 ` Helge Hafting
2008-05-16 13:20 ` Adrian Bunk
2008-05-16 16:20 ` Andi Kleen
2008-05-16 19:47 ` David Miller
2008-05-16 23:28 ` Rick Jones
2008-05-15 18:04 ` Jeff Garzik
2008-05-15 18:17 ` Rick Jones
2008-05-15 18:31 ` Jeff Garzik
2008-05-15 18:47 ` Kok, Auke
2008-05-15 19:21 ` Jeff Garzik
2008-05-15 20:01 ` Chris Peterson
2008-05-15 20:16 ` Jeff Garzik
2008-05-15 20:39 ` Kok, Auke
2008-05-15 21:47 ` Theodore Tso
2008-05-15 21:58 ` Jeff Garzik
2008-05-15 22:29 ` Henrique de Moraes Holschuh
2008-05-15 22:44 ` Jeff Garzik
2008-05-15 23:02 ` Henrique de Moraes Holschuh
2008-05-15 23:36 ` Theodore Tso
2008-05-15 23:46 ` Henrique de Moraes Holschuh
2008-05-15 23:33 ` Theodore Tso
2008-05-15 23:58 ` Henrique de Moraes Holschuh
2008-05-16 13:21 ` Lennart Sorensen
2008-05-16 13:40 ` Jeff Garzik
2008-05-16 13:59 ` Will Newton
2008-05-16 14:15 ` Lennart Sorensen
2008-05-16 14:27 ` Jeff Garzik
2008-05-16 15:10 ` Alan Cox
2008-05-16 17:36 ` Lennart Sorensen
2008-05-16 18:11 ` Alan Cox
2008-05-16 18:40 ` Kok, Auke
2008-05-16 18:41 ` Lennart Sorensen
2008-05-16 18:42 ` Lennart Sorensen
2008-05-16 20:04 ` Alan Cox
2008-05-16 20:39 ` Lennart Sorensen
2008-05-16 20:46 ` Alan Cox
2008-05-16 20:34 ` Benny Amorsen
2008-05-25 15:02 ` Glen Turner
2008-05-25 19:33 ` Benny Amorsen
2008-05-17 4:55 ` Chris Peterson
2008-05-25 15:09 ` Glen Turner
2008-05-25 23:27 ` Theodore Tso
2008-05-26 13:43 ` Alejandro Riveira Fernández
2008-05-26 15:14 ` Bill Fink
2008-05-26 21:07 ` Krzysztof Halasa
2008-05-26 21:52 ` Bill Fink
2008-05-26 22:11 ` Ben Hutchings [this message]
2008-05-27 16:44 ` Rick Jones
2008-05-30 19:50 ` Pavel Machek
2008-05-25 14:55 ` Glen Turner
[not found] ` <482C8550 <20080516161029.44ded734@core>
2008-05-16 20:08 ` Gilles Espinasse
2008-05-17 22:02 ` Adrian Bunk
2008-05-18 6:41 ` [PATCH] drivers/net: remove network drivers' last few uses ofIRQF_SAMPLE_RANDOM Gilles Espinasse
2008-05-18 9:54 ` Alan Cox
2008-05-18 12:02 ` Adrian Bunk
2008-05-18 12:24 ` Theodore Tso
2008-05-18 14:43 ` Adrian Bunk
2008-05-15 21:55 ` [PATCH] drivers/net: remove network drivers' last few uses of IRQF_SAMPLE_RANDOM Adrian Bunk
2008-05-15 22:04 ` Jeff Garzik
2008-05-15 22:27 ` Theodore Tso
2008-05-15 22:13 ` Jesper Juhl
2008-05-15 22:34 ` Theodore Tso
2008-05-15 22:57 ` Jesper Juhl
2008-05-18 0:36 ` Matt Mackall
2008-05-15 22:42 ` Jeff Garzik
-- strict thread matches above, loose matches on Subject: below --
2010-04-10 5:29 Chris Peterson
2010-04-15 6:42 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20080526221119.GF28241@solarflare.com \
--to=bhutchings@solarflare$(echo .)com \
--cc=alan@lxorguk$(echo .)ukuu.org.uk \
--cc=ariveira@gmail$(echo .)com \
--cc=auke-jan.h.kok@intel$(echo .)com \
--cc=billfink@mindspring$(echo .)com \
--cc=cpeterso@cpeterso$(echo .)com \
--cc=gdt@gdt$(echo .)id.au \
--cc=jeff@garzik$(echo .)org \
--cc=jesse.brandeburg@intel$(echo .)com \
--cc=khc@pm$(echo .)waw.pl \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=lsorense@csclub$(echo .)uwaterloo.ca \
--cc=netdev@vger$(echo .)kernel.org \
--cc=rick.jones2@hp$(echo .)com \
--cc=tytso@MIT$(echo .)EDU \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox