Re: [PATCH v5 11/11] intel_sgx: driver documentation

From: Jarkko Sakkinen
Date: Mon Nov 20 2017 - 17:46:34 EST

On Wed, Nov 15, 2017 at 12:54:12PM +0100, Peter Zijlstra wrote:
> On Tue, Nov 14, 2017 at 10:49:48PM +0200, Jarkko Sakkinen wrote:
> > In these cases IA32_FEATURE_CONTROL[17] would be zeroed before locking
> > the feature control, which would mean that the kernel could not write
> > new values with wrmsr for the root key hash.
> > The question is whether we want to allow this or not. If the answer is
> > no, a check can be added to the driver initialization code whether 17 is
> > set, and if not, it driver would fail to initialize.
> That has my vote; I would not trust a firmware/BIOS key.

Please note that it does not have a key to look inside the enclave. The
enclave is protected by two means:

1. The CPU asserts the memory accesses to it.
2. The CPU encrypts/decrypts in L1 in order to protect from physical
attacks and peripherals that have potential spy the bus.