linux-kernel - Re: [PATCH v6 00/11] Intel SGX Driver

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Date:   Wed, 20 Dec 2017 01:33:46 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Pavel Machek <pavel@....cz>
Cc:     platform-driver-x86@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        "David S. Miller" <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Grzegorz Andrejczuk <grzegorz.andrejczuk@...el.com>,
        Haim Cohen <haim.cohen@...el.com>,
        Ingo Molnar <mingo@...nel.org>,
        Janakarajan Natarajan <Janakarajan.Natarajan@....com>,
        Jim Mattson <jmattson@...gle.com>,
        Kan Liang <Kan.liang@...el.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Kyle Huey <me@...ehuey.com>, Len Brown <len.brown@...el.com>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        "open list:FILESYSTEMS (VFS and infrastructure)" 
        <linux-fsdevel@...r.kernel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Piotr Luc <piotr.luc@...el.com>,
        Radim Kr??m???? <rkrcmar@...hat.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>
Subject: Re: [PATCH v6 00/11] Intel SGX Driver

On Tue, 2017-12-12 at 15:07 +0100, Pavel Machek wrote:
> On Sat 2017-11-25 21:29:17, 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.
> 
> Would you list guarantees provided by SGX?
> 
> For example, host can still observe timing of cachelines being
> accessed by "protected" app, right? Can it also introduce bit flips?
> 
> 								Pavel

I'll give a more proper response to this now that all the reported major
issues in the code have been fixed in v9.

Yes, SGX is vulnerable to the L1 cacheline timing attacks. Jethro
Beekman wrote a great summary about this on early March:

  https://jbeekman.nl/blog/2017/03/sgx-side-channel-attacks/

The counter measures are the same as without SGX. It really does not
add or degrade security in this area.

/Jarkko