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Date:   Mon, 26 Nov 2018 13:51:45 -0800
From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     Andy Lutomirski <luto@amacapital.net>
Cc:     Andy Lutomirski <luto@kernel.org>,
        "Dr. Greg Wettstein" <greg@enjellic.com>, X86 ML <x86@kernel.org>,
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        "Christopherson, Sean J" <sean.j.christopherson@intel.com>,
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        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
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Subject: Re: [PATCH v17 18/23] platform/x86: Intel SGX driver
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On Sun, Nov 25, 2018 at 08:22:35AM -0800, Andy Lutomirski wrote:
> Agreed. What I’m proposing adds additional security if the kernel is
> *not* compromised.

And even if the kernel is compromised evil use will detected quicker
i.e. compromissed kernel is "better" than a kernel that allows to
use provisioning freely.

> There are other ways to accomplish it that might be better in some
> respects.  For example, there could be /dev/sgx and
> /dev/sgx_rights/provision.  The former exposes the whole sgx API,
> except that it doesn’t allow provisioning by default. The latter does
> nothing by itself. To run a provisioning enclave, you open both nodes,
> then do something like:
> 
> ioctl(sgx, SGX_IOC_ADD_RIGHT, sgx_provisioning);
> 
> This requires extra syscalls, but it doesn’t have the combinatorial
> explosion problem.

I like this design because it is extendable. I'm now also in the same
page why we need to protect provisioning in the first place. I would
slight restructure this as

/dev/sgx/control
/dev/sgx/attributes/provision

Looks cleaner and the root /dev directory is less polluted.

BTW, off-topic from this but should we remove ENCLAVE from IOC names as
they all concern enclaves anyway? Seems kind of redundant. I.e.

SGX_IOC_ENCLAVE_CREATE -> SGX_IOC_CREATE
SGX_IOC_ENCLAVE_ADD_PAGE -> SGX_IOC_ADD_PAGE
SGX_IOC_ENCLAVE_INIT -> SGX_IOC_INIT

/Jarkko