linux-kernel - Re: [PATCH v5 0/7] /dev/random

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Message-ID: <CACXcFmmu3aHHdwDFE+OEd5Q4ymLhLcm9ERfk1Lq9ijsMp_Czhw@mail.gmail.com>
Date:	Sun, 19 Jun 2016 16:47:35 -0400
From:	Sandy Harris <sandyinchina@...il.com>
To:	Pavel Machek <pavel@....cz>
Cc:	Stephan Mueller <smueller@...onox.de>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Theodore Tso <tytso@....edu>, Andi Kleen <andi@...stfloor.org>,
	Jason Cooper <cryptography@...edaemon.net>,
	John Denker <jsd@...n.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Joe Perches <joe@...ches.com>,
	George Spelvin <linux@...izon.com>,
	linux-crypto@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 0/7] /dev/random - a new approach

On Sun, Jun 19, 2016 at 3:36 PM, Pavel Machek <pavel@....cz> wrote:

>> The following patch set provides a different approach to /dev/random ...
>
> Dunno. It is very similar to existing rng, AFAICT.

I do not think so. A lot of the basic principles are the same of course,
but Stephan is suggesting some real changes. On the other hand, I'm
not sure all of them are good ideas & Ted has already incorporated
some into the driver, so it is debatable how much here is really useful.

> And at the very least, constants in existing RNG could be tuned
> to provide "entropy at the boot time".

No, this is a rather hard problem & just tweaking definitely will
not solve it. Ted's patches, Stephan's, mine, the grsecurity
stuff and the kernel hardening project all have things that
might help, but as far as I can see there is no complete
in-kernel solution yet.

Closest thing I have seen to a solution are Denker's suggestions at:
http://www.av8n.com/computer/htm/secure-random.htm#sec-boot-image

Those, though, require changes to build & installation methods
& it might be hard to get distros & device vendors to do it.

> So IMO this should be re-done as tweaks to existing design, not as
> completely new RNG.

I agree, & I think Stephan has already done some of that.