linux-kernel - Re: [PATCH v1 3/3] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <63dd7d4b-4729-9e03-cd8f-956b94eab0d9@pengutronix.de>
Date:   Wed, 24 Mar 2021 10:26:14 +0100
From:   Ahmad Fatoum <a.fatoum@...gutronix.de>
To:     Mimi Zohar <zohar@...ux.ibm.com>,
        Horia Geantă <horia.geanta@....com>,
        Jonathan Corbet <corbet@....net>,
        David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        James Bottomley <jejb@...ux.ibm.com>
Cc:     "kernel@...gutronix.de" <kernel@...gutronix.de>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Aymen Sghaier <aymen.sghaier@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Udit Agarwal <udit.agarwal@....com>,
        Jan Luebbe <j.luebbe@...gutronix.de>,
        David Gstir <david@...ma-star.at>,
        Franck Lenormand <franck.lenormand@....com>,
        Sumit Garg <sumit.garg@...aro.org>,
        "keyrings@...r.kernel.org" <keyrings@...r.kernel.org>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH v1 3/3] KEYS: trusted: Introduce support for NXP
 CAAM-based trusted keys

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?

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 |