linux-kernel - Re: [PATCH v43 01/15] Linux Random Number Generator

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Date:   Tue, 30 Nov 2021 16:39:10 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Jeffrey Walton <noloader@...il.com>
Cc:     Stephan Mueller <smueller@...onox.de>,
        Simo Sorce <simo@...hat.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>, Tso Ted <tytso@....edu>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        Willy Tarreau <w@....eu>, Nicolai Stange <nstange@...e.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Alexander E. Patrakov" <patrakov@...il.com>,
        "Ahmed S. Darwish" <darwish.07@...il.com>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Vito Caputo <vcaputo@...garu.com>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.cz>, Ray Strode <rstrode@...hat.com>,
        William Jon McCann <mccann@....edu>,
        zhangjs <zachary@...shancloud.com>,
        Andy Lutomirski <luto@...nel.org>,
        Florian Weimer <fweimer@...hat.com>,
        Lennart Poettering <mzxreary@...inter.de>,
        Peter Matthias <matthias.peter@....bund.de>,
        Marcelo Henrique Cerri <marcelo.cerri@...onical.com>,
        Neil Horman <nhorman@...hat.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Julia Lawall <julia.lawall@...ia.fr>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Andy Lavr <andy.lavr@...il.com>,
        Eric Biggers <ebiggers@...nel.org>,
        Petr Tesarik <ptesarik@...e.cz>,
        John Haxby <john.haxby@...cle.com>,
        Alexander Lobakin <alobakin@...lbox.org>,
        Jirka Hladky <jhladky@...hat.com>
Subject: Re: [PATCH v43 01/15] Linux Random Number Generator

On Tue, Nov 30, 2021 at 10:13:26AM -0500, Jeffrey Walton wrote:
> On Tue, Nov 30, 2021 at 9:04 AM Greg Kroah-Hartman
> <gregkh@...uxfoundation.org> wrote:
> >
> > On Tue, Nov 30, 2021 at 07:24:15AM -0500, Jeffrey Walton wrote:
> > > On Mon, Nov 29, 2021 at 6:07 PM Greg Kroah-Hartman
> > > <gregkh@...uxfoundation.org> wrote:
> > > > ...
> > > > Sometimes, yes, it is valid to have different implementations for things
> > > > that do different things in the same area (like filesystems), but for a
> > > > core function of the kernel, so far the existing random maintainer has
> > > > not wanted to have multiple implementations.  Same goes for other parts
> > > > of the kernel, it's not specific only to this one very tiny driver.
> > > >
> > > > As a counterpoint, we do not allow duplicate drivers that control the
> > > > same hardware types in the tree.  We have tried that in the past and it
> > > > was a nightmare to support and maintain and just caused massive user
> > > > confusion as well.  One can argue that the random driver is in this same
> > > > category.
> > >
> > > I think an argument could be made that they are different drivers
> > > since they have different requirements and security goals. I don't
> > > think it matters where the requirements came from, whether it was ad
> > > hoc from the developer, NIST, KISA, CRYPTREC, NESSIE, or another
> > > organization.
> > >
> > > Maybe the problem is with the name of the driver? Perhaps the current
> > > driver should be named random-linux, Stephan's driver should be named
> > > random-nist, and the driver should be wired up based on a user's
> > > selection. That should sidestep the problems associated with the
> > > "duplicate drivers" policy.
> >
> > The "problem" here is that the drivers/char/random.c file has three users,
> > the userspace /dev/random and syscall api, the in-kernel "here's some
> > entropy for the random core to use" api, and the in-kernel "give me some
> > random data" api.
> >
> > Odds are, you REALLY do not want the in-kernel calls to be pulling from
> > the "random-government-crippled-specification" implementation, right?
> 
> It's not a question of whether some folks want it or not. They have to
> accept it due to policy. They have no choice in the matter.

I strongly doubt that policy dictates all of the current calls to
get_random_*() require that they return data that is dictated by that
policy.  If so, that's not a valid specification for a variety of
reasons (i.e. it will break other specification requirements...)

thanks,

greg k-h