linux-kernel - Re: [PATCH 07/10] random: add new get_random_bytes

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Message-ID: <20120705195025.GH31225@thunk.org>
Date:	Thu, 5 Jul 2012 15:50:25 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Linux Kernel Developers List <linux-kernel@...r.kernel.org>,
	w@....eu, ewust@...ch.edu, zakir@...ch.edu, greg@...ah.com,
	mpm@...enic.com, nadiah@...ucsd.edu, jhalderm@...ch.edu,
	tglx@...utronix.de, davem@...emloft.net, stable@...nel.org
Subject: Re: [PATCH 07/10] random: add new get_random_bytes_arch() function

On Thu, Jul 05, 2012 at 11:35:12AM -0700, Linus Torvalds wrote:
> 
> If "get_random_bytes()" doesn't use the hw rng when it exists, it is
> broken. It's that simple.
> 

It is using the HW RNG when it exists; it will ultimately call
xfer_secondary_pool, which will mix in inputs from the hw rng.  So we
do get all of the security of the HW RNG.  Currently all of the
callers of the get_random_bytes() have to accomodate the fact that the
HW RNG might not be there (on non-Intel architectures if nothing
else), so get_random_bytes() can't be used in any hot paths as it is.

So we *are* using the hw rng; we're just not using it to the exclusion
of anything else.

						- Ted
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