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Subject: Re: [PATCH v1 0/3] KEYS: trusted: Introduce support for NXP
 CAAM-based trusted keys
To:     Richard Weinberger <richard@nod.at>,
        Sumit Garg <sumit.garg@linaro.org>
Cc:     Jarkko Sakkinen <jarkko@kernel.org>,
        horia geanta <horia.geanta@nxp.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        aymen sghaier <aymen.sghaier@nxp.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        davem <davem@davemloft.net>,
        James Bottomley <jejb@linux.ibm.com>,
        kernel <kernel@pengutronix.de>,
        David Howells <dhowells@redhat.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Steffen Trumtrar <s.trumtrar@pengutronix.de>,
        Udit Agarwal <udit.agarwal@nxp.com>,
        Jan Luebbe <j.luebbe@pengutronix.de>,
        david <david@sigma-star.at>,
        Franck Lenormand <franck.lenormand@nxp.com>,
        linux-integrity <linux-integrity@vger.kernel.org>,
        "open list, ASYMMETRIC KEYS" <keyrings@vger.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        LSM <linux-security-module@vger.kernel.org>
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From:   Ahmad Fatoum <a.fatoum@pengutronix.de>
Message-ID: <ea261e53-8f5d-ac52-f3b9-7f2db4532244@pengutronix.de>
Date:   Thu, 1 Apr 2021 15:30:25 +0200
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Hello Richard, Sumit,

On 01.04.21 15:17, Richard Weinberger wrote:
> Sumit,
> 
> ----- Ursprüngliche Mail -----
>> Von: "Sumit Garg" <sumit.garg@linaro.org>
>> IIUC, this would require support for multiple trusted keys backends at
>> runtime but currently the trusted keys subsystem only supports a
>> single backend which is selected via kernel module parameter during
>> boot.
>>
>> So the trusted keys framework needs to evolve to support multiple
>> trust sources at runtime but I would like to understand the use-cases
>> first. IMO, selecting the best trust source available on a platform
>> for trusted keys should be a one time operation, so why do we need to
>> have other backends available at runtime as well?
> 
> I thought about devices with a TPM-Chip and CAAM.
> IMHO allowing only one backend at the same time is a little over simplified. 

It is, but I'd rather leave this until it's actually needed.
What can be done now is adopting a format for the exported keys that would
make this extension seamless in future.

Cheers,
Ahmad

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