From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephan =?ISO-8859-1?Q?M=FCller?= Subject: Re: [PATCH 3/8] random: trigger random_ready callback upon crng_init == 1 Date: Wed, 18 Jan 2017 18:09:14 +0100 Message-ID: <1721766.rHn5SRrCCO@tauon.atsec.com> References: <3254875.f5A5oHPdxF@positron.chronox.de> <3576149.HSfW5KObBF@positron.chronox.de> <20170118041250.x7wszcasd4dplj3h@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org To: Theodore Ts'o Return-path: Received: from mail.eperm.de ([89.247.134.16]:55586 "EHLO mail.eperm.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750874AbdARRKL (ORCPT ); Wed, 18 Jan 2017 12:10:11 -0500 In-Reply-To: <20170118041250.x7wszcasd4dplj3h@thunk.org> Sender: linux-crypto-owner@vger.kernel.org List-ID: Am Dienstag, 17. Januar 2017, 23:12:50 CET schrieb Theodore Ts'o: Hi Theodore, > On Tue, Dec 27, 2016 at 11:39:57PM +0100, Stephan Müller wrote: > > The random_ready callback mechanism is intended to replicate the > > getrandom system call behavior to in-kernel users. As the getrandom > > system call unblocks with crng_init == 1, trigger the random_ready > > wakeup call at the same time. > > It was deliberate that random_ready would only get triggered with > crng_init==2. > > In general I'm assuming kernel callers really want real randomness (as > opposed to using prandom), where as there's a lot of b.s. userspace > users of kernel randomness (for things that really don't require > cryptographic randomness, e.g., for salting Python dictionaries, > systemd/udev using /dev/urandom for non-cryptographic, non-security > applications etc.) Users of getrandom want to ensure that they get random data from a DRNG that is seeded, just like in-kernel users may want if they choose the callback- approach. I do not understand why there should be different treatment of in-kernel vs user space callers in that respect. (And yes, I do not want to open a discussion whether crng_init==1 can considered as a sufficiently seeded DRNG as such discussion will lead nowhere.) Ciao Stephan