linux-kernel - Re: [PATCH v14 19/19] x86/sgx: Driver documentation

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Message-ID: <20181018095727.GC10861@amd>
Date:   Thu, 18 Oct 2018 11:57:27 +0200
From:   Pavel Machek <pavel@....cz>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     x86@...nel.org, platform-driver-x86@...r.kernel.org,
        dave.hansen@...el.com, sean.j.christopherson@...el.com,
        nhorman@...hat.com, npmccallum@...hat.com, serge.ayoun@...el.com,
        shay.katz-zamir@...el.com, linux-sgx@...r.kernel.org,
        andriy.shevchenko@...ux.intel.com,
        Jonathan Corbet <corbet@....net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v14 19/19] x86/sgx: Driver documentation

On Thu 2018-10-18 02:45:27, Jarkko Sakkinen wrote:
> On Mon, 15 Oct 2018, Pavel Machek wrote:
> >On Tue 2018-09-25 16:06:56, 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.
> >>+In a way you can think that SGX provides inverted sandbox. It protects the
> >>+application from a malicious host.
> >
> >Well, recently hardware had some problems keeping its
> >promises. So... what about rowhammer, meltdown and spectre?
> 
> Doesn't hardware always have this problem over time?

No, not really.

In this case, tries to protect from hardware "attacks" done by machine
owner. That job is theoretically impossible, so you have harder
situation than most..

> >Which ones apply, which ones do not, and on what cpu generations?
> 
> Definitely should be refined.
> 
> Meltdowns approach AFAIK does not work because reads outside the enclave
> will always have a predefined value (-1) but only if the page is present,
> which was later exploited in the Foreshadow attack.

What about L1tf and https://github.com/lsds/spectre-attack-sgx ?

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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