On 6/13/2017 11:00 AM, Andy Lutomirski wrote:
On Mon, Jun 12, 2017 at 3:08 PM, Huang, Kai <kai.huang@xxxxxxxxxxxxxxx> 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.
Hi Andy,
Sorry for late reply.
What is the issue if host and guest run provisioning enclave from
different vendor, for example, host runs intel's provisioning enclave,
and guest runs other vendor's provisioning enclave? Or different guests
run provisioning enclaves from different vendors?
One reason I am asking is that, on Xen (where we don't have concept of
*host*), it's likely that we won't apply any policy at Xen hypervisor at
all, and guests will be able to run any enclave from any signer as their
wish.
Sorry that I don't understand (or kind of forgot) the issues here.
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.
Assuming the enclave hash means measurement of enclave, and assuming we
have a policy that we only allow enclave from one signer to run, would
you also elaborate the issue that, if host and guest run enclaves from
different signer? If host has such policy, and we are allowing creating
guests on such host, I think that typically we will have the same policy
in the guest (vetted by guest's kernel). The owner of that host should
be aware of the risk (if there's any) by creating guest and run enclave
inside it.
Thanks,
-Kai
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.
