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From: "H. Peter Anvin" <hpa@zytor.com>
To: "Theodore Ts'o" <tytso@mit.edu>,
	Linux Kernel Developers List <linux-kernel@vger.kernel.org>,
	torvalds@linux-foundation.org, w@1wt.eu, ewust@umich.edu,
	zakir@umich.edu, greg@kroah.com, mpm@selenic.com,
	nadiah@cs.ucsd.edu, jhalderm@umich.edu, tglx@linutronix.de,
	davem@davemloft.net, stable@kernel.org,
	DJ Johnson <dj.johnson@intel.com>, Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH 07/10] random: add new get_random_bytes_arch() function
Date: Wed, 25 Jul 2012 20:16:19 -0700	[thread overview]
Message-ID: <5010B683.1010708@zytor.com> (raw)
In-Reply-To: <20120725151000.GA30996@thunk.org>

On 07/25/2012 08:10 AM, Theodore Ts'o wrote:
> Aside from whether it's better to do this step in
> xfer_secondary_pool() or extract_entropy() ...

By the way, I looked at doing this in xfer_secondary_pool()... the 
problem there is that xfer_secondary_pool() is called exactly once per 
invocation of extract_entropy() and so there is no way to make it inject 
the same amount of material as it consumes.

One could put it in extract_entropy[_user]() and if you prefer I'll 
rewrite the patch to do that, however that code would look very similar 
to the one in extract_buf() -- pretty much the same code in the caller 
rather than the callee -- but would have the same downside with being 
processed on 10-byte chunks because the final buffer might be misaligned 
and/or partial.  It would mean just running it once rather than twice 
per output datum, but I actually expected you would prefer the 
additional mashing and security margin.

	-hpa

P.S. Anyone who have any insider info on when we can expect the SHA-3 
selection?  Switching to SHA-2 at this time with SHA-3 around the corner 
(and based on numbers I have seen, likely to be faster) seems a bit silly...

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.


  parent reply	other threads:[~2012-07-26  3:17 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-05 18:12 [PATCH 00/10] /dev/random fixups Theodore Ts'o
2012-07-05 18:12 ` [PATCH 01/10] random: make 'add_interrupt_randomness()' do something sane Theodore Ts'o
2012-07-05 18:47   ` Matt Mackall
2012-07-05 18:52     ` Linus Torvalds
2012-07-05 21:39       ` Matt Mackall
2012-07-05 21:47         ` Linus Torvalds
2012-07-05 22:00           ` Theodore Ts'o
2012-07-05 22:21             ` Linus Torvalds
2012-07-05 22:31               ` Matt Mackall
2012-07-05 22:35                 ` Linus Torvalds
2012-07-05 23:21                 ` Theodore Ts'o
2012-07-06  2:59                   ` Linus Torvalds
2012-07-06 13:01                     ` Theodore Ts'o
2012-07-06 16:24                       ` Linus Torvalds
2012-07-06 16:52                         ` Theodore Ts'o
2012-07-09 19:15                           ` Matt Mackall
2012-07-25 18:43                         ` Thomas Gleixner
     [not found]   ` <CAGsuqq2MWuFnY7PMb_2ddBNNJr80xB_JW+Wryq3mhhmQuEojpg@mail.gmail.com>
2012-07-06 21:59     ` Theodore Ts'o
2012-07-05 18:12 ` [PATCH 02/10] random: use lockless techniques when mixing entropy pools Theodore Ts'o
2012-07-05 18:18   ` Linus Torvalds
2012-07-05 18:19   ` Greg KH
2012-07-05 23:09     ` Theodore Ts'o
2012-07-05 19:10   ` Matt Mackall
2012-07-05 19:47     ` Theodore Ts'o
2012-07-05 20:45       ` Matt Mackall
2012-07-05 18:12 ` [PATCH 03/10] random: create add_device_randomness() interface Theodore Ts'o
2012-07-05 18:12 ` [PATCH 04/10] usb: feed USB device information to the /dev/random driver Theodore Ts'o
2012-07-05 18:12 ` [PATCH 05/10] net: feed /dev/random with the MAC address when registering a device Theodore Ts'o
2012-07-05 18:12 ` [PATCH 06/10] random: use the arch-specific rng in xfer_secondary_pool Theodore Ts'o
2012-07-05 18:49   ` Linus Torvalds
2012-07-05 18:12 ` [PATCH 07/10] random: add new get_random_bytes_arch() function Theodore Ts'o
2012-07-05 18:35   ` Linus Torvalds
2012-07-05 19:50     ` Theodore Ts'o
2012-07-05 21:45     ` Matt Mackall
2012-07-25  3:37   ` H. Peter Anvin
2012-07-25  7:22     ` Ingo Molnar
2012-07-25 15:10     ` Theodore Ts'o
2012-07-25 15:19       ` H. Peter Anvin
2012-07-25 17:37       ` [PATCH] random: mix in architectural randomness in extract_buf() H. Peter Anvin
2012-07-25 23:50         ` Ben Hutchings
2012-07-26  0:32           ` H. Peter Anvin
2012-07-28  2:39         ` Theodore Ts'o
2012-07-28  2:48           ` H. Peter Anvin
2012-07-26  3:16       ` H. Peter Anvin [this message]
2012-07-26  3:24         ` [PATCH 07/10] random: add new get_random_bytes_arch() function H. Peter Anvin
2012-07-05 18:12 ` [PATCH 08/10] random: unify mix_pool_bytes() and mix_pool_bytes_entropy() Theodore Ts'o
2012-07-05 18:12 ` [PATCH 09/10] random: add tracepoints for easier debugging and verification Theodore Ts'o
2012-07-05 18:12 ` [PATCH 10/10] MAINTAINERS: Theodore Ts'o is taking over the random driver Theodore Ts'o
2012-07-06 11:40 ` [PATCH 00/10] /dev/random fixups Fengguang Wu
2012-07-06 12:44   ` Theodore Ts'o
2012-07-20 20:15 ` [PATCH] dmi: Feed DMI table to /dev/random driver Tony Luck
2012-07-20 21:03   ` Matt Mackall
2012-07-21  0:56   ` Theodore Ts'o
2012-07-21  1:19     ` Tony Luck
2012-07-21  2:02       ` Theodore Ts'o
2012-07-23 16:47         ` [PATCH] random: Add comment to random_initialize() Tony Luck

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