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From:   Sumit Garg <sumit.garg@linaro.org>
Date:   Thu, 1 Apr 2021 19:42:49 +0530
Message-ID: <CAFA6WYNjS=1JsAPfh=j8D6HUn9rCEADyZxtWvYWuvbz_FsVbTQ@mail.gmail.com>
Subject: Re: [PATCH v1 0/3] KEYS: trusted: Introduce support for NXP
 CAAM-based trusted keys
To:     Richard Weinberger <richard@nod.at>
Cc:     Ahmad Fatoum <a.fatoum@pengutronix.de>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        horia geanta <horia.geanta@nxp.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
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        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>,
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        Franck Lenormand <franck.lenormand@nxp.com>,
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On Thu, 1 Apr 2021 at 19:29, Richard Weinberger <richard@nod.at> wrote:
>
> Sumit,
>
> ----- Urspr=C3=BCngliche Mail -----
> > Von: "Sumit Garg" <sumit.garg@linaro.org>
> > In this case why would one prefer to use CAAM when you have standards
> > compliant TPM-Chip which additionally offers sealing to specific PCR
> > (integrity measurement) values.
>
> I don't think we can dictate what good/sane solutions are and which are n=
ot.
> Both CAAM and TPM have pros and cons, I don't see why supporting both is =
a bad idea.

I didn't mean to say that supporting both is a bad idea but rather I
was looking for use-cases where one time selection of the best trust
source (whether it be a TPM or TEE or CAAM etc.) for a platform
wouldn't suffice for user needs.

>
> >> > IMHO allowing only one backend at the same time is a little over sim=
plified.
> >>
> >> 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 w=
ould
> >> make this extension seamless in future.
> >>
> >
> > +1
>
> As long we don't make multiple backends at runtime impossible I'm
> fine and will happily add support for it when needed. :-)
>

You are most welcome to add such support. I will be happy to review it.

-Sumit

> Thanks,
> //richard