>> On Nov 25, 2018, at 6:53 AM, Jarkko Sakkinen >> <jarkko.sakki...@linux.intel.com> wrote: >> >> On Sat, Nov 24, 2018 at 09:21:14AM -0800, Jarkko Sakkinen wrote: >> On Thu, Nov 22, 2018 at 07:21:08AM -0800, Andy Lutomirski wrote: >>>> At a high level, addressing these issues is straight forward. First, >>>> the driver needs to support authorization equivalent to that which is >>>> implemented in the current Intel Launch Enclave, ie. control over the >>>> SGX_FLAGS_PROVISION_KEY attribute. >>> >>> I agree, hence my email :) >> >> Started to scratch my head that is it really an issue that any enclave >> can provision in the end? >> >> Direct quote from your first response: >> >> "In particular, the ability to run enclaves with the provisioning bit set >> is somewhat sensitive, since it effectively allows access to a stable >> fingerprint of the system." >> >> As can be seen from the key derivation table this does not exactly hold >> so you should refine your original argument before we can consider any >> type of change. >> >> I just don't see what it is so wrong for any enclave to be able to tell >> that it really is an enclave. > > I mean I can understand why Greg wants LE although I don't understand > what benefit does it bring to anyone to lock in for enclave to allow > to identify itself. > > What you are proposing does not really bring any additional security if > we consider a threat model where the kernel is an adversary but it makes > the software stack more clanky to use.
Agreed. What I’m proposing adds additional security if the kernel is *not* compromised. 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.
