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    SubjectRe: [PATCH 0/6] Intel Secure Guard Extensions
    On Mon, May 02, 2016 at 11:37:52AM -0400, Austin S. Hemmelgarn wrote:
    > 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).

    The code in enclave binary is in clear text so it does not really
    allow you to completely hide any code. It's a signed binary, not
    encypted binary.

    /Jarkko

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