From: "Serge E. Hallyn" <serge@hallyn.com>
To: James Bottomley <jejb@linux.ibm.com>
Cc: "Mimi Zohar" <zohar@linux.ibm.com>,
"Ahmad Fatoum" <a.fatoum@pengutronix.de>,
"Horia Geantă" <horia.geanta@nxp.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"David Howells" <dhowells@redhat.com>,
"Jarkko Sakkinen" <jarkko@kernel.org>,
"kernel@pengutronix.de" <kernel@pengutronix.de>,
"James Morris" <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
"Aymen Sghaier" <aymen.sghaier@nxp.com>,
"Herbert Xu" <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
"Udit Agarwal" <udit.agarwal@nxp.com>,
"Jan Luebbe" <j.luebbe@pengutronix.de>,
"David Gstir" <david@sigma-star.at>,
"Franck Lenormand" <franck.lenormand@nxp.com>,
"Sumit Garg" <sumit.garg@linaro.org>,
"keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>
Subject: Re: [PATCH v1 3/3] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys
Date: Thu, 1 Apr 2021 20:49:50 -0500 [thread overview]
Message-ID: <20210402014950.GA6897@mail.hallyn.com> (raw)
In-Reply-To: <9ba89168d8c4f1e3d6797a0b3713e152ac6388fd.camel@linux.ibm.com>
On Wed, Mar 24, 2021 at 09:14:02AM -0700, James Bottomley wrote:
> On Tue, 2021-03-23 at 14:07 -0400, Mimi Zohar wrote:
> > On Tue, 2021-03-23 at 17:35 +0100, Ahmad Fatoum wrote:
> > > Hello Horia,
> > >
> > > On 21.03.21 21:48, Horia Geantă wrote:
> > > > On 3/16/2021 7:02 PM, Ahmad Fatoum wrote:
> > > > [...]
> > > > > +struct trusted_key_ops caam_trusted_key_ops = {
> > > > > + .migratable = 0, /* non-migratable */
> > > > > + .init = trusted_caam_init,
> > > > > + .seal = trusted_caam_seal,
> > > > > + .unseal = trusted_caam_unseal,
> > > > > + .exit = trusted_caam_exit,
> > > > > +};
> > > > caam has random number generation capabilities, so it's worth
> > > > using that
> > > > by implementing .get_random.
> > >
> > > If the CAAM HWRNG is already seeding the kernel RNG, why not use
> > > the kernel's?
> > >
> > > Makes for less code duplication IMO.
> >
> > Using kernel RNG, in general, for trusted keys has been discussed
> > before. Please refer to Dave Safford's detailed explanation for not
> > using it [1].
> >
> > thanks,
> >
> > Mimi
> >
> > [1]
> > https://lore.kernel.org/linux-integrity/BCA04D5D9A3B764C9B7405BBA4D4A3C035F2A38B@ALPMBAPA12.e2k.ad.ge.com/
>
> I still don't think relying on one source of randomness to be
> cryptographically secure is a good idea. The fear of bugs in the
> kernel entropy pool is reasonable, but since it's widely used they're
> unlikely to persist very long.
I'm not sure I agree - remember
https://www.schneier.com/blog/archives/2008/05/random_number_b.html ? You'd
surely expect that to have been found quickly.
> Studies have shown that some TPMs
> (notably the chinese manufactured ones) have suspicious failures in
> their RNGs:
>
> https://www.researchgate.net/publication/45934562_Benchmarking_the_True_Random_Number_Generator_of_TPM_Chips
>
> And most cryptograhpers recommend using a TPM for entropy mixing rather
> than directly:
>
> https://blog.cryptographyengineering.com/category/rngs/
>
> The TPMFail paper also shows that in spite of NIST certification
> things can go wrong with a TPM:
>
> https://tpm.fail/
In this thread I've seen argument over "which is better" and "which is user api",
but noone's mentioned fips. Unfortunately, so long as kernel rng refuses to be
fips-friendly (cf https://lkml.org/lkml/2020/9/21/157), making CAAM based trusted
keys depend on kernel rng would make them impossible to use in fips certified
applications without a forked kernel.
So I definitely am in favor of a config or kernel command line option to drive
which rng to use.
next prev parent reply other threads:[~2021-04-02 1:58 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 17:01 [PATCH v1 0/3] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys Ahmad Fatoum
2021-03-16 17:01 ` [PATCH v1 1/3] crypto: caam - add in-kernel interface for blob generator Ahmad Fatoum
2021-03-21 20:46 ` Horia Geantă
2021-03-23 16:41 ` Ahmad Fatoum
2021-03-16 17:01 ` [PATCH v1 2/3] KEYS: trusted: implement fallback to kernel RNG Ahmad Fatoum
2021-03-16 17:01 ` [PATCH v1 3/3] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys Ahmad Fatoum
2021-03-16 19:22 ` Jarkko Sakkinen
2021-03-17 13:58 ` Ahmad Fatoum
2021-03-16 23:14 ` Richard Weinberger
2021-03-17 7:39 ` Sumit Garg
2021-03-17 8:07 ` Richard Weinberger
2021-03-17 14:02 ` Ahmad Fatoum
2021-03-30 21:28 ` Richard Weinberger
2021-03-21 20:48 ` Horia Geantă
2021-03-23 16:35 ` Ahmad Fatoum
2021-03-23 18:07 ` Mimi Zohar
2021-03-24 9:26 ` Ahmad Fatoum
2021-03-24 10:47 ` Sumit Garg
2021-03-24 14:07 ` Ahmad Fatoum
2021-03-25 5:26 ` Sumit Garg
2021-03-27 12:41 ` David Gstir
2021-03-28 20:37 ` Jarkko Sakkinen
2021-03-29 10:11 ` Ahmad Fatoum
2021-03-31 23:29 ` Jarkko Sakkinen
2021-03-30 7:26 ` Sumit Garg
2021-03-31 23:30 ` Jarkko Sakkinen
2021-04-01 7:41 ` Ahmad Fatoum
2021-03-30 21:47 ` Eric Biggers
2021-03-31 23:31 ` Jarkko Sakkinen
2021-03-31 23:34 ` Eric Biggers
2021-04-01 1:11 ` Herbert Xu
2021-04-01 5:50 ` Jarkko Sakkinen
2021-04-01 6:03 ` Eric Biggers
2021-04-01 5:46 ` Jarkko Sakkinen
2021-03-24 16:14 ` James Bottomley
2021-03-24 20:49 ` Mimi Zohar
2021-03-24 21:58 ` James Bottomley
2021-04-02 1:49 ` Serge E. Hallyn [this message]
2021-03-31 18:35 ` Richard Weinberger
2021-04-01 10:15 ` Ahmad Fatoum
2021-04-01 10:23 ` Richard Weinberger
2021-03-16 23:10 ` [PATCH v1 0/3] " Richard Weinberger
2021-03-17 14:08 ` Ahmad Fatoum
2021-03-30 21:50 ` Richard Weinberger
2021-04-01 10:04 ` Ahmad Fatoum
2021-04-01 10:20 ` Richard Weinberger
2021-04-01 10:28 ` Ahmad Fatoum
2021-04-01 10:53 ` Richard Weinberger
2021-04-01 10:57 ` Ahmad Fatoum
2021-04-01 11:05 ` Richard Weinberger
2021-04-01 11:13 ` Ahmad Fatoum
2021-04-01 11:16 ` Richard Weinberger
2021-03-30 22:04 ` Richard Weinberger
2021-03-30 22:16 ` James Bottomley
2021-03-31 18:36 ` Richard Weinberger
2021-03-31 18:49 ` James Bottomley
2021-03-31 19:36 ` Richard Weinberger
2021-04-01 10:06 ` Ahmad Fatoum
2021-04-01 13:20 ` Sumit Garg
2021-04-01 18:26 ` James Bottomley
2021-04-01 12:55 ` Sumit Garg
2021-04-01 13:17 ` Richard Weinberger
2021-04-01 13:30 ` Ahmad Fatoum
2021-04-01 13:52 ` Sumit Garg
2021-04-01 13:59 ` Richard Weinberger
2021-04-01 14:12 ` Sumit Garg
2021-04-01 11:11 ` David Howells
2021-03-21 20:01 ` Horia Geantă
2021-03-23 16:34 ` Ahmad Fatoum
2021-03-24 6:23 ` Sumit Garg
2021-03-23 16:37 ` Ahmad Fatoum
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