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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Mon, 10 Jan 2022 23:19:56 +0100
Message-ID: <CAHmME9rmWBA02SyeFiiGZ8=kydYJSJwcYPscBrTBzoXMEPH9sQ@mail.gmail.com>
Subject: Re: [PATCH v43 01/15] Linux Random Number Generator
To:     "Theodore Ts'o" <tytso@mit.edu>
Cc:     Marcelo Henrique Cerri <marcelo.cerri@canonical.com>,
        Simo Sorce <simo@redhat.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jeffrey Walton <noloader@gmail.com>,
        Stephan Mueller <smueller@chronox.de>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Willy Tarreau <w@1wt.eu>, Nicolai Stange <nstange@suse.de>,
        LKML <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        "Alexander E. Patrakov" <patrakov@gmail.com>,
        "Ahmed S. Darwish" <darwish.07@gmail.com>,
        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>,
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        John Haxby <john.haxby@oracle.com>,
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        Jirka Hladky <jhladky@redhat.com>,
        Eric Biggers <ebiggers@kernel.org>
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On Mon, Jan 10, 2022 at 9:18 PM Theodore Ts'o <tytso@mit.edu> wrote:
> In general, you need FIPS
> certification for some specific use cases / application.  For example,
> if you're going for PCI compliance, then you might only need FIPS
> compliance for your OpenSSL library.  What the FIPS certification lab
> might consider acceptable for its entropy for its DRBG is an
> interesting question.  For some, simply having the OpenSSL library use
> RDSEED or RDRAND might be sufficient.  Or it could talk to an actual
> physical RNG device.
>
> So disabling getrandom() is probably not necessary, just so long as
> you can demonstrate that the FIPS cryptographic module --- i.e., the
> OpenSSL library --- is getting its entropy from an acceptable source.

I don't know exactly what these people think they want, but what you
say seems probably correct.

> I suspect what's actually going on is that some enterprise customers
> have FIPS complaince on a check-off list, and they aren't actually
> getting a formal FIPS certification.  Or they only need something to
> wave under the noses of their PCI certification company, and so the
> question is what makes them happy.

Right.

> And this is why some FIPS certification have gotten by just *fine*
> with a pure userspace OpenSSL library as their FIPS cryptographic
> module.  Where you draw the line between a "blessed" entropy source
> and one that's just hand-waving is really at the discretion of the
> certification lab.

Hah, probably correct.

So, seen this way, and combined with the solution provided at [1] (or
similar) for people who think they need something there, it seems like
the FIPS people can likely get what they need without really needing
to involve the kernel anyway.

Jason

[1] https://lore.kernel.org/lkml/YdynXjhhuQfbYuSb@zx2c4.com/