From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Sumit Garg <sumit.garg@linaro.org>
Cc: "Mimi Zohar" <zohar@linux.ibm.com>,
"Horia Geantă" <horia.geanta@nxp.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"David Howells" <dhowells@redhat.com>,
"Jarkko Sakkinen" <jarkko@kernel.org>,
"James Bottomley" <jejb@linux.ibm.com>,
"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>,
"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: Wed, 24 Mar 2021 15:07:30 +0100 [thread overview]
Message-ID: <557b92d2-f3b8-d136-7431-419429f0e059@pengutronix.de> (raw)
In-Reply-To: <CAFA6WYOw_mQwOUN=onhzb7zCTyYDBrcx0E7C3LRk6nPLAVCWEQ@mail.gmail.com>
Hello Sumit,
On 24.03.21 11:47, Sumit Garg wrote:
> On Wed, 24 Mar 2021 at 14:56, Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:
>>
>> Hello Mimi,
>>
>> On 23.03.21 19:07, Mimi Zohar wrote:
>>> On Tue, 2021-03-23 at 17:35 +0100, Ahmad Fatoum wrote:
>>>> On 21.03.21 21:48, Horia Geantă wrote:
>>>>> 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].
>>
>> The argument seems to boil down to:
>>
>> - TPM RNG are known to be of good quality
>> - Trusted keys always used it so far
>>
>> Both are fine by me for TPMs, but the CAAM backend is new code and neither point
>> really applies.
>>
>> get_random_bytes_wait is already used for generating key material elsewhere.
>> Why shouldn't new trusted key backends be able to do the same thing?
>>
>
> Please refer to documented trusted keys behaviour here [1]. New
> trusted key backends should align to this behaviour and in your case
> CAAM offers HWRNG so we should be better using that.
Why is it better?
Can you explain what benefit a CAAM user would have if the trusted key
randomness comes directly out of the CAAM instead of indirectly from
the kernel entropy pool that is seeded by it?
> Also, do update documentation corresponding to CAAM as a trusted keys backend.
Yes. The documentation should be updated for CAAM and it should describe
how the key material is derived. Will do so for v2.
Cheers,
Ahmad
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/tree/Documentation/security/keys/trusted-encrypted.rst#n87
>
> -Sumit
>
>> Cheers,
>> Ahmad
>>
>>>
>>> thanks,
>>>
>>> Mimi
>>>
>>> [1]
>>> https://lore.kernel.org/linux-integrity/BCA04D5D9A3B764C9B7405BBA4D4A3C035F2A38B@ALPMBAPA12.e2k.ad.ge.com/
>>>
>>>
>>>
>>
>> --
>> Pengutronix e.K. | |
>> Steuerwalder Str. 21 | http://www.pengutronix.de/ |
>> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
>> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
>
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
next prev parent reply other threads:[~2021-03-24 14:08 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 [this message]
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
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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