linux-kernel - Re: [PATCH v11 00/13] Intel SGX1 support

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Date:   Mon, 10 Dec 2018 09:27:04 +0100
From:   Pavel Machek <pavel@....cz>
To:     Josh Triplett <josh@...htriplett.org>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>, x86@...nel.org,
        platform-driver-x86@...r.kernel.org, dave.hansen@...el.com,
        sean.j.christopherson@...el.com, nhorman@...hat.com,
        npmccallum@...hat.com, Alexei Starovoitov <ast@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...e.de>,
        "David S. Miller" <davem@...emloft.net>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
        "open list:INTEL SGX" <intel-sgx-kernel-dev@...ts.01.org>,
        Janakarajan Natarajan <Janakarajan.Natarajan@....com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        "open list:KERNEL VIRTUAL MACHINE FOR X86 (KVM/x86)" 
        <kvm@...r.kernel.org>, Len Brown <len.brown@...el.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        "open list:CRYPTO API" <linux-crypto@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:SPARSE CHECKER" <linux-sparse@...r.kernel.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>
Subject: Re: [PATCH v11 00/13] Intel SGX1 support

On Sun 2018-12-09 23:47:17, Josh Triplett wrote:
> On Sun, Dec 09, 2018 at 09:06:00PM +0100, Pavel Machek wrote:
> ...
> > > > > The default permissions for the device are 600.
> > > > 
> > > > Good. This does not belong to non-root.
> > > 
> > > There are entirely legitimate use cases for using this as an
> > > unprivileged user. However, that'll be up to system and distribution
> > > policy, which can evolve over time, and it makes sense for the *initial*
> > > kernel permission to start out root-only and then adjust permissions via
> > > udev.
> > 
> > Agreed.
> > 
> > > Building a software certificate store. Hardening key-agent software like
> > > ssh-agent or gpg-agent. Building a challenge-response authentication
> > > system. Providing more assurance that your server infrastructure is
> > > uncompromised. Offloading computation to a system without having to
> > > fully trust that system.
> > 
> > I think you can do the crypto stuff... as crypto already verifies the
> > results. But I don't think you can do the computation offload.
> 
> You can, as long as you can do attestation.

You can not, because random errors are very easy to trigger for person
with physical access, as I explained in the part of email you
stripped.

> > > As one of many possibilities, imagine a distcc that didn't have to trust
> > > the compile nodes. The compile nodes could fail to return results at
> > > all, but they couldn't alter the results.
> > 
> > distcc on untrusted nodes ... oh yes, that would be great.
> > 
> > Except that you can't do it, right? :-).
> > 
> > First, AFAICT it would be quite hard to get gcc to run under SGX. But
> > maybe you have spare month or three and can do it.
> 
> Assuming you don't need to #include files, gcc seems quite simple to run
> in an enclave: data in, computation inside, data out.

So is there a plan to run dynamically linked binaries inside enclave?
Or maybe even python/shell scripts? It looked to me like virtual
memory will be "interesting" for enclaves.


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

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