Re: [Tee-dev] [RFC v2 0/6] Introduce TEE based Trusted Keys support

From: Sumit Garg <sumit.garg@linaro.org>
To: Janne Karhunen <janne.karhunen@gmail.com>
Cc: dhowells@redhat.com, Daniel Thompson <daniel.thompson@linaro.org>,
	Rouven Czerwinski <r.czerwinski@pengutronix.de>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	jejb@linux.ibm.com, Jonathan Corbet <corbet@lwn.net>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	"tee-dev @ lists . linaro . org" <tee-dev@lists.linaro.org>,
	linux-security-module@vger.kernel.org, keyrings@vger.kernel.org,
	Mimi Zohar <zohar@linux.ibm.com>,
	Casey Schaufler <casey@schaufler-ca.com>,
	linux-integrity@vger.kernel.org,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	"Serge E. Hallyn" <serge@hallyn.com>
Subject: Re: [Tee-dev] [RFC v2 0/6] Introduce TEE based Trusted Keys support
Date: Thu, 01 Aug 2019 07:58:47 +0000	[thread overview]
Message-ID: <CAFA6WYPt4q+jaJbaoauXKr2qKgBHvtQ663s4t=W3nuPJPe2xpw@mail.gmail.com> (raw)
In-Reply-To: <CAE=NcraqD9FNM0Gk9UGhPGi3heVzZrAKGc1gNZxoe1OnDaQ=pA@mail.gmail.com>

On Thu, 1 Aug 2019 at 13:00, Janne Karhunen <janne.karhunen@gmail.com> wrote:
>
> On Thu, Aug 1, 2019 at 9:50 AM Rouven Czerwinski
> <r.czerwinski@pengutronix.de> wrote:
>
> > > I'm aware of it - I have implemented a large part of the GP TEE APIs
> > > earlier (primarily the crypto functions). Does the TEE you work with
> > > actually support GP properly? Can I take a look at the code?
> >
> > AFAIK Sumit is working with the OP-TEE implementation, which can be
> > found on github: https://github.com/op-tee/optee_os
>
> Thanks, I will take a look.

For documentation, refer to: https://optee.readthedocs.io/

> The fundamental problem with these things
> is that there are infinite amount of ways how TEEs and ROTs can be
> done in terms of the hardware and software. I really doubt there are 2
> implementations in existence that are even remotely compatible in real
> life.

I agree with you regarding implementation specific nature of TEE but
having a standardized client interface does solves the problem.

> As such, all things TEE/ROT would logically really belong in the
> userland and thanks to the bpfilter folks now the umh logic really
> makes that possible ... I think. The key implementation I did was just
> an RFC on the concept, what if we start to move the stuff that really
> belongs in the userspace to this pseudo-userland. It's not kernel, but
> it's not commonly accessible userland either. The shared memory would
> also work without any modifications between the umh based TEE/ROT
> driver and the userland if needed.
>
> Anyway, just my .02c. I guess having any new support in the kernel for
> new trust sources is good and improvement from the current state. I
> can certainly make my stuff work with your setup as well, what ever
> people think is the best.

Yes your implementation can very well fit under trusted keys
abstraction framework without creating a new keytype: "ext-trusted".

-Sumit

>
>
> --
> Janne