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Date:   Fri, 8 Nov 2019 10:05:01 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     Stephen Smalley <sds@tycho.nsa.gov>
Cc:     Sean Christopherson <sean.j.christopherson@intel.com>,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-sgx@vger.kernel.org, akpm@linux-foundation.org,
        dave.hansen@intel.com, nhorman@redhat.com, npmccallum@redhat.com,
        serge.ayoun@intel.com, shay.katz-zamir@intel.com,
        haitao.huang@intel.com, andriy.shevchenko@linux.intel.com,
        tglx@linutronix.de, kai.svahn@intel.com, bp@alien8.de,
        josh@joshtriplett.org, luto@kernel.org, kai.huang@intel.com,
        rientjes@google.com, cedric.xing@intel.com, puiterwijk@redhat.com,
        linux-security-module@vger.kernel.org,
        Suresh Siddha <suresh.b.siddha@intel.com>
Subject: Re: [PATCH v23 12/24] x86/sgx: Linux Enclave Driver
Message-ID: <20191108080501.GA3370@linux.intel.com>
References: <20191028210324.12475-1-jarkko.sakkinen@linux.intel.com>
 <20191028210324.12475-13-jarkko.sakkinen@linux.intel.com>
 <173a196e-fa6b-23b8-c818-dfca6cdadcc6@tycho.nsa.gov>
 <20191031211721.GD10507@linux.intel.com>
 <f91d788c-b372-8e2f-7ffb-995f501b5d6b@tycho.nsa.gov>
 <4bf866ae-adc8-7902-3714-b62e548d8584@tycho.nsa.gov>
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On Fri, Nov 01, 2019 at 01:16:59PM -0400, Stephen Smalley wrote:
> On 11/1/19 11:32 AM, Sean Christopherson wrote:
> > On Fri, Nov 01, 2019 at 09:28:17AM -0400, Stephen Smalley wrote:
> > > On 11/1/19 9:16 AM, Stephen Smalley wrote:
> > > > So, IIUC, that means that merging the driver will create a regression with
> > > > respect to LSM control over executable mappings that will only be
> > > > rectified at some future point in time if/when someone submits LSM hooks
> > > > or calls to existing hooks to restore such control.? That doesn't seem
> > > > like a good idea.? Why can't you include at least that basic level of
> > > > control now?? It is one thing to defer finer grained control or
> > > > SGX-specific access controls to the future - that I can understand.? But
> > > > introducing a regression in the existing controls is not really ok.
> > > 
> > > Unless you are arguing that the existing checks on mmap/mprotect of
> > > /dev/sgx/enclave are a coarse-grained approximation (effectively requiring
> > > WX to the file or execmem for any user of SGX).
> > 
> > Yes, that's the argument as running any enclave will require RWX access to
> > /dev/sgx/enclave.  EXECMEM won't trigger for SGX users as /dev/sgx/enclave
> > must be MAP_SHARED and it's a non-private file (not backed by anonymous
> > inode, in case I got the file terminology wrong).
> 
> Ok, so for SELinux's purposes, one will need to allow :file { open ioctl map
> read write execute } to whatever type is ultimately assigned to
> /dev/sgx/enclave in order to use SGX.

AFAIK yes.

/Jarkko