From: Stephan Mueller <smueller@chronox.de>
To: "Theodore Ts'o" <tytso@mit.edu>
Cc: "Jörn Engel" <joern@logfs.org>, "H. Peter Anvin" <hpa@zytor.com>,
"Linux Kernel Developers List" <linux-kernel@vger.kernel.org>,
macro@linux-mips.org, ralf@linux-mips.org, dave.taht@gmail.com,
blogic@openwrt.org, andrewmcgr@gmail.com, geert@linux-m68k.org,
tg@mirbsd.de
Subject: Re: [PATCH,RFC] random: collect cpu randomness
Date: Mon, 03 Feb 2014 14:06:06 +0100 [thread overview]
Message-ID: <1986906.jste579uFo@tauon> (raw)
In-Reply-To: <20140203013922.GB6264@thunk.org>
Am Sonntag, 2. Februar 2014, 20:39:22 schrieb Theodore Ts'o:
Hi Theodore,
>On Sun, Feb 02, 2014 at 10:25:31PM +0100, Stephan Mueller wrote:
>> Second, when I offered my initial patch which independently collects
>> some entropy on the CPU execution timing, I got shot down with one
>> concern raised by Ted, and that was about whether a user can
>> influence the entropy collection process.
>
>Um, that wasn't my concern. After all, when we sample keyboard timing
>while trying to generate a GPG key, of course the user can and does
>influence the entropy collection process.
Thank you for clarifying and sorry that I misunderstood you.
>I really like Jörn's tests doing repeated boot testing and observing
>on a SMP system, the slab allocation pattern is quite deterministic.
>So even though the numbers might *look* random, an attacker with deep
>knowledge of how the kernel was compiled and what memory allocations
>get done during the boot sequence would be able to quite successfuly
>measure it.
>
>I'm guessing that indeed, on a 4-CPU KVM system, what you're measuring
Please let me point out that I am not testing on KVM, but on Linux
running natively on the hardware. All major CPUs were tested. Even tests
are executed on bare metal, i.e. without any OS and interrupts disabled.
But I will explain that in a separate email and do not want to hijack
this thread.
Ciao
Stephan
next prev parent reply other threads:[~2014-02-03 13:06 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-02 20:36 [PATCH,RFC] random: collect cpu randomness Jörn Engel
2014-02-02 21:25 ` Stephan Mueller
2014-02-03 1:24 ` Jörn Engel
2014-02-03 1:28 ` H. Peter Anvin
2014-02-03 13:36 ` Stephan Mueller
2014-02-03 1:39 ` Theodore Ts'o
2014-02-03 3:35 ` Jörn Engel
2014-02-03 12:54 ` Thorsten Glaser
2014-02-03 13:06 ` Stephan Mueller [this message]
2014-02-03 15:50 ` Jörn Engel
2014-02-03 16:37 ` Theodore Ts'o
2014-02-03 18:48 ` Jörn Engel
2014-03-23 18:00 ` [PATCH] random: mix all saved registers into entropy pool Jörn Engel
2014-02-03 21:54 ` [PATCH,RFC] random: collect cpu randomness Maciej W. Rozycki
2014-02-03 22:44 ` Theodore Ts'o
2014-02-06 22:20 ` Kees Cook
2014-02-06 22:21 ` Dave Taht
2014-02-07 7:44 ` Jörn Engel
2014-02-20 9:50 ` Paolo Bonzini
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=1986906.jste579uFo@tauon \
--to=smueller@chronox.de \
--cc=andrewmcgr@gmail.com \
--cc=blogic@openwrt.org \
--cc=dave.taht@gmail.com \
--cc=geert@linux-m68k.org \
--cc=hpa@zytor.com \
--cc=joern@logfs.org \
--cc=linux-kernel@vger.kernel.org \
--cc=macro@linux-mips.org \
--cc=ralf@linux-mips.org \
--cc=tg@mirbsd.de \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.