Re: [PATCH 0/6] Intel Secure Guard Extensions

From: Austin S. Hemmelgarn
Date: Mon May 02 2016 - 11:38:17 EST

On 2016-04-29 16:17, Jarkko Sakkinen wrote:
On Tue, Apr 26, 2016 at 09:00:10PM +0200, Pavel Machek wrote:
On Mon 2016-04-25 20:34:07, Jarkko Sakkinen wrote:
Intel(R) SGX is a set of CPU instructions that can be used by
applications to set aside private regions of code and data. The code
outside the enclave is disallowed to access the memory inside the
enclave by the CPU access control.

The firmware uses PRMRR registers to reserve an area of physical memory
called Enclave Page Cache (EPC). There is a hardware unit in the
processor called Memory Encryption Engine. The MEE encrypts and decrypts
the EPC pages as they enter and leave the processor package.

What are non-evil use cases for this?

I'm not sure what you mean by non-evil.

I would think that this should be pretty straightforward. Pretty much every security technology integrated in every computer in existence has the potential to be used by malware for various purposes. Based on a cursory look at SGX, it is pretty easy to figure out how to use this to hide arbitrary code from virus scanners and the OS itself unless you have some way to force everything to be a debug enclave, which entirely defeats the stated purpose of the extensions. I can see this being useful for tight embedded systems. On a desktop which I have full control of physical access to though, it's something I'd immediately turn off, because the risk of misuse is so significant (I've done so on my new Thinkpad L560 too, although that's mostly because Linux doesn't support it yet).