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Subject: Re: [PATCH v20 00/28] Intel SGX1 support
From:   Andy Lutomirski <luto@amacapital.net>
In-Reply-To: <49b28ca1-6e66-87d9-2202-84c58f13fb99@fortanix.com>
Date:   Fri, 19 Apr 2019 14:31:57 -0700
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Andy Lutomirski <luto@kernel.org>,
        "Dr. Greg" <greg@enjellic.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
        "linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Christopherson, Sean J" <sean.j.christopherson@intel.com>,
        "nhorman@redhat.com" <nhorman@redhat.com>,
        "npmccallum@redhat.com" <npmccallum@redhat.com>,
        "Ayoun, Serge" <serge.ayoun@intel.com>,
        "Katz-zamir, Shay" <shay.katz-zamir@intel.com>,
        "Huang, Haitao" <haitao.huang@intel.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        "Svahn, Kai" <kai.svahn@intel.com>, Borislav Petkov <bp@alien8.de>,
        Josh Triplett <josh@joshtriplett.org>,
        "Huang, Kai" <kai.huang@intel.com>,
        David Rientjes <rientjes@google.com>
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References: <20190417103938.7762-1-jarkko.sakkinen@linux.intel.com> <20190418171059.GA20819@wind.enjellic.com> <09ebfa1d-c03d-c1fe-ff0f-d99287b6ec3c@intel.com> <20190419141732.GA2269@wind.enjellic.com> <CALCETrV=wAsyWxtxQJ7y0xNrzkE863hTfU6Ysej48Gk9yPFJZw@mail.gmail.com> <43aa8fdd-e777-74cb-e3f0-d36805ffa18b@fortanix.com> <alpine.DEB.2.21.1904192233390.3174@nanos.tec.linutronix.de> <8c5133bc-1301-24ca-418d-7151a6eac0e2@fortanix.com> <alpine.DEB.2.21.1904192248550.3174@nanos.tec.linutronix.de> <e1478f70-7e44-6e3e-2aaf-1b12a96328ed@fortanix.com> <2AE80EA3-799E-4808-BBE4-3872F425BCF8@amacapital.net> <49b28ca1-6e66-87d9-2202-84c58f13fb99@fortanix.com>
To:     Jethro Beekman <jethro@fortanix.com>
Sender: linux-kernel-owner@vger.kernel.org
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> On Apr 19, 2019, at 2:19 PM, Jethro Beekman <jethro@fortanix.com> wrote:
>=20
>> .
>>=20
>> If we start enforcing equivalent rules on SGX, then the current API will s=
imply not allow enclaves to be loaded =E2=80=94 no matter how you slice it, l=
oading an enclave with the current API is indistinguishable from making arbi=
trary data executable.
>=20
> Yes this is exactly what I intended here: a very simple change that
> stops SGX from confusing LSM. Just by enforcing that everything that
> looks like a memory write (EADD, EAUG, EDBGWR, etc.) actually requires
> write permissions, reality and LSM should be on the same page.
>=20
> If you want to go further and actually allow this behavior when your LSM
> would otherwise prohibit it, presumably the same workarounds that exist
> for JITs can be used for SGX.
>=20
>=20

I do think we need to follow LSM rules.  But my bigger point is that there a=
re policies that don=E2=80=99t allow JIT at all. I think we should arrange t=
he SGX API so it=E2=80=99s still usable when such a policy is in effect.=