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

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Date:   Wed, 20 Dec 2017 15:18:13 +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 Wed, Dec 20, 2017 at 01:33:46AM +0200, Jarkko Sakkinen wrote:
> 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.

This came up even in my patch set :-) I.e. I switched to kernel AES-NI
from TinyCrypt's AES because the latter is not timing resistant.

/Jarkko