linux-kernel - Re: [PATCH] random: Don't overwrite CRNG state in crng

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Message-ID: <12520331.ppYG2MRRyi@positron.chronox.de>
Date:   Thu, 09 Feb 2017 10:26:19 +0100
From:   Stephan Müller <smueller@...onox.de>
To:     Alden Tondettar <alden.tondettar@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Theodore Ts'o <tytso@....edu>, Arnd Bergmann <arnd@...db.de>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] random: Don't overwrite CRNG state in crng_initialize()

Am Donnerstag, 9. Februar 2017, 02:04:32 CET schrieb Alden Tondettar:

Hi Alden,

> On Thu, Feb 09, 2017 at 07:47:25AM +0100, Greg Kroah-Hartman wrote:
> > On Wed, Feb 08, 2017 at 08:31:26PM -0700, Alden Tondettar wrote:
> > > In short, the situation is:
> > > 
> > > A) No usable hardware RNG or arch_get_random() (or we don't trust it...)
> > 
> > Wait, why would you not trust arch_get_random()?  Is it broken somehow
> > on some arches?  If so, why not fix that as well?
> 
> arch_get_random() makes use of RDRAND and similar CPU features. Some people
> do not wish to trust black-box RNG implementations.

Furthermore, this function is only implemented on x86. On other arches, it is 
a noop.

Ciao
Stephan