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. /Jarkko
