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From:   Andy Lutomirski <luto@amacapital.net>
Date:   Wed, 28 Nov 2018 13:52:00 -0800
Message-ID: <CALCETrV4UA5bn6dkq5aVycApx1ubq-rho_z=sHhxABbOSGZWMw@mail.gmail.com>
Subject: Re: [PATCH v17 18/23] platform/x86: Intel SGX driver
To:     "Dr. Greg Wettstein" <greg@enjellic.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Andrew Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
        Platform Driver <platform-driver-x86@vger.kernel.org>,
        linux-sgx@vger.kernel.org, Dave Hansen <dave.hansen@intel.com>,
        "Christopherson, Sean J" <sean.j.christopherson@intel.com>,
        nhorman@redhat.com, npmccallum@redhat.com,
        "Ayoun, Serge" <serge.ayoun@intel.com>, shay.katz-zamir@intel.com,
        haitao.huang@linux.intel.com,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Svahn, Kai" <kai.svahn@intel.com>, mark.shanahan@intel.com,
        Suresh Siddha <suresh.b.siddha@intel.com>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Darren Hart <dvhart@infradead.org>,
        Andy Shevchenko <andy@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Tue, Nov 27, 2018 at 12:55 AM Dr. Greg <greg@enjellic.com> wrote:
> Since the thread has become a bit divergent I wanted to note that we
> have offered a proposal for a general policy management framework
> based on MRSIGNER values.  This framework is consistent with the SGX
> security model, ie. cryptographic rather then DAC based policy
> controls.  This framework also allows a much more flexible policy
> implementation that doesn't result in combinatoric issues.

Can you give a concrete explanation of a problem that your proposal
would solve?  As far as I can tell, it gets rid of a case in which an
unprivileged attacker who can run enclaves but hasn't compromised the
kernel can learn the PPID and other SGX-related permanent platform
identifiers, but it does nothing to prevent the same attacker from
learning non-SGX-related permanent identifiers, nor does it prevent
the attacker from using the Intel quoting enclave (unless configured
in a surprising way) and thus attesting to a remote system.

So what problem does it solve?