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Date:   Sun, 9 Dec 2018 23:47:17 -0800
From:   Josh Triplett <josh@joshtriplett.org>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>, x86@kernel.org,
        platform-driver-x86@vger.kernel.org, dave.hansen@intel.com,
        sean.j.christopherson@intel.com, nhorman@redhat.com,
        npmccallum@redhat.com, Alexei Starovoitov <ast@kernel.org>,
        Andi Kleen <ak@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Borislav Petkov <bp@suse.de>,
        "David S. Miller" <davem@davemloft.net>,
        David Woodhouse <dwmw@amazon.co.uk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
        "open list:INTEL SGX" <intel-sgx-kernel-dev@lists.01.org>,
        Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        "open list:KERNEL VIRTUAL MACHINE FOR X86 (KVM/x86)" 
        <kvm@vger.kernel.org>, Len Brown <len.brown@intel.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        "open list:CRYPTO API" <linux-crypto@vger.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
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        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Vikas Shivappa <vikas.shivappa@linux.intel.com>
Subject: Re: [PATCH v11 00/13] Intel SGX1 support
Message-ID: <20181210074717.GA9880@localhost>
References: <20180608171216.26521-1-jarkko.sakkinen@linux.intel.com>
 <20180612105011.GA26931@amd>
 <20180619145943.GC8034@linux.intel.com>
 <20180619200414.GA3143@amd>
 <20180619214833.GA5873@localhost>
 <20181209200600.GA11608@amd>
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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.

> > 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.