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From:   Andy Lutomirski <luto@kernel.org>
Date:   Tue, 14 May 2019 08:13:36 -0700
Message-ID: <CALCETrVbgTCnPo=PAq0-KoaRwt--urrPzn==quAJ8wodCpkBkw@mail.gmail.com>
Subject: Re: [PATCH v20 00/28] Intel SGX1 support
To:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Jethro Beekman <jethro@fortanix.com>,
        "Xing, Cedric" <cedric.xing@intel.com>,
        "Hansen, Dave" <dave.hansen@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Dr. Greg" <greg@enjellic.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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On Tue, May 14, 2019 at 3:43 AM Jarkko Sakkinen
<jarkko.sakkinen@linux.intel.com> wrote:
>
> On Mon, May 13, 2019 at 01:29:26PM +0300, Jarkko Sakkinen wrote:
> > I did study through SDK's file format and realized that it does not
> > does make sense after all to embed one.
> >
> > To implement it properly you would probably need a new syscall (lets say
> > sgx_load_enclave) and also that enclaves are not just executables
> > binaries. It is hard to find a generic format for them as applications
> > range from simply protecting part of an application to running a
> > containter inside enclave.
>
> I'm still puzzling what kind of changes you were discussing considering
> SGX_IOC_ENCLAVE_ADD_PAGE.

I think it's as simple as requiring that, if SECINFO.X is set, then
the src pointer points to the appropriate number of bytes of
executable memory.  (Unless there's some way for an enclave to change
SECINFO after the fact -- is there?)  Sadly, we don't really have the
a nice in-kernel API for that right now.  You could do
down_read(mmap_sem) and find_vma().  Arguably there is no value to
checking that PKRU allows execute to the data.

Hey, Dave, if you're still paying attention to this thread, should we
have copy_from_user_exec() that does the right thing wrt the page
permissions and PKRU.