Re: [intel-sgx-kernel-dev] [PATCH 08/10] kvm: vmx: add guest's IA32_SGXLEPUBKEYHASHn runtime switch support

[Andy Lutomirski <luto@kernel.org>]

On Mon, Jun 12, 2017 at 3:08 PM, Huang, Kai <kai.huang@linux.intel.com> wrote:
>
> I don't know whether SGX driver will have restrict on running provisioning
> enclave. In my understanding provisioning enclave is always from Intel.
> However I am not expert here and probably be wrong. Can you point out
> *exactly* what restricts in host must/should be applied to guest so that
> Jarkko can know whether he will support those restricts or not? Otherwise I
> don't think we even need to talk about this topic at current stage.
>

The whole point is that I don't know.  But here are two types of
restriction I can imagine demand for:

1. Only a particular approved provisioning enclave may run (be it
Intel's or otherwise -- with a non-Intel LE, I think you can launch a
non-Intel provisioning enclave).  This would be done to restrict what
types of remote attestation can be done. (Intel supplies a remote
attestation service that uses some contractual policy that I don't
know.  Maybe a system owner wants a different policy applied to ISVs.)
 Imposing this policy on guests more or less requires filtering EINIT.

2. For kiosk-ish or single-purpose applications, I can imagine that
you would want to allow a specific list of enclave signers or even
enclave hashes. Maybe you would allow exactly one enclave hash.  You
could kludge this up with a restrictive LE policy, but you could also
do it for real by implementing the specific restriction in the kernel.
Then you'd want to impose it on the guest, and you'd do it by
filtering EINIT.

For the time being, I don't expect either policy to be implemented
right away, but I bet that something like this will eventually happen.