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From:   Nathaniel McCallum <npmccallum@redhat.com>
Date:   Mon, 25 Jun 2018 17:06:12 -0400
Message-ID: <CAOASepPb5zKz_HDyM+s8wLmaN3oN7+OtuDLmocP_9w5Hdq3c6A@mail.gmail.com>
Subject: Re: [intel-sgx-kernel-dev] [PATCH v11 13/13] intel_sgx: in-kernel
 launch enclave
To:     luto@kernel.org
Cc:     Neil Horman <nhorman@redhat.com>, sean.j.christopherson@intel.com,
        jethro@fortanix.com, jarkko.sakkinen@linux.intel.com,
        x86@kernel.org, platform-driver-x86@vger.kernel.org,
        linux-kernel@vger.kernel.org, mingo@redhat.com,
        intel-sgx-kernel-dev@lists.01.org, hpa@zytor.com,
        dvhart@infradead.org, tglx@linutronix.de, andy@infradead.org,
        Peter Jones <pjones@redhat.com>
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On Thu, Jun 21, 2018 at 6:49 PM Andy Lutomirski <luto@kernel.org> wrote:
>
> On Thu, Jun 21, 2018 at 12:11 PM Nathaniel McCallum
> <npmccallum@redhat.com> wrote:
> >
> > If this is acceptable for everyone, my hope is the following:
> >
> > 1. Intel would split the existing code into one of the following
> > schemas (I don't care which):
> >   A. three parts: UEFI module, FLC-only kernel driver and user-space
> > launch enclave
> >   B. two parts: UEFI module (including launch enclave) and FLC-only
> > kernel driver
> >
> > 2. Intel would release a reproducible build of the GPL UEFI module
> > sources signed with a SecureBoot trusted key and provide an
> > acceptable[0] binary redistribution license.
> >
> > 3. The kernel community would agree to merge the kernel driver given
> > the above criteria (and, obviously, acceptable kernel code).
> >
> > The question of how to distribute the UEFI module and possible launch
> > enclave remains open. I see two options: independent distribution and
> > bundling it in linux-firmware. The former may be a better
> > technological fit since the UEFI module will likely need to be run
> > before the kernel (and the boot loader; and shim). However, the latter
> > has the benefit of already being a well-known entity to our downstream
> > distributors. I could go either way on this.
>
> This is a lot of complication and effort for a gain that is not
> entirely clear.

Root kits and evil maid attacks are two worth considering.

> I really really really do *not* want to see Intel or
> anyone else start enforcing policy on which programs can and cannot
> run using this mechanism.

We already do this. It is called SecureBoot.

> (This is exactly why non-FLC systems aren't
> about to be supported upstream.)  So my preference is to not merge
> anything that supports this type of use case unless there is
> compelling evidence that it is (a) genuinely useful, (b) will be used
> to improve security and (c) won't be abused for, say, revenue
> purposes.

I think there are benefits for (a) and (b). I agree with you about
(c). But, again, we already have SecureBoot.