From: Florian Weimer <fw@deneb.enyo.de>
Subject: Re: [PATCH v24 00/12] /dev/random - a new approach with full SP800-90B compliance
Date: Tue, 12 Nov 2019 14:23:10 +0100
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In-Reply-To: <6157374.ptSnyUpaCn@positron.chronox.de> ("Stephan
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To: Stephan =?iso-8859-1?Q?M=FCller?= <smueller@chronox.de>
Cc: Arnd Bergmann <arnd@arndb.de>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, linux-crypto@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>, linux-api@vger.kernel.org, "Eric W. Biederman" <ebiederm@xmission.com>, "Alexander E. Patrakov" <patrakov@gmail.com>, "Ahmed S. Darwish" <darwish.07@gmail.com>, "Theodore Y. Ts'o" <tytso@mit.edu>, Willy Tarreau <w@1wt.eu>, Matthew Garrett <mjg59@srcf.ucam.org>, Vito Caputo <vcaputo@pengaru.com>, Andreas Dilger <adilger.kernel@dilger.ca>, Jan Kara <jack@suse.cz>, Ray Strode <rstrode@redhat.com>, William Jon McCann <mccann@jhu.edu>, zhangjs <zachary@baishancloud.com>, Andy Lutomirski <luto@kernel.org>, Florian Weimer <fweimer@redhat.com>, Lennart Poettering <mzxreary@0pointer.de>, Nicolai Stange <nstange@sus>
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* Stephan Müller:

> * support deactivation of TRNG (i.e. blocking behavior of /dev/random)
>   at compile time. If deactivated, /dev/random behaves like
>   getrandom(2).

I don't quite understand this comment.  Doesn't getrandom with the
GRND_RANDOM always behave like /dev/random?  Presumably, without the
TRNG tap, the GRND_RANDOM flag for getrandom is ignored, and reading
from /dev/random behaves like reading from /dev/urandom.

Anyway, reading the accompanying PDF, this looks rather impressive:
the userspace bootstrapping problem is gone (the issue where waiting
for more entropy prevents the collection of more entropy), *and* we
can still make the standards people happy.

(Replying from my other account due to mail issues, sorry.)