Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 4 Jun 2019 00:05:34 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Stephen Smalley <sds@tycho.nsa.gov>,
        "Xing, Cedric" <cedric.xing@intel.com>,
        William Roberts <bill.c.roberts@gmail.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        LSM List <linux-security-module@vger.kernel.org>,
        Paul Moore <paul@paul-moore.com>,
        Eric Paris <eparis@parisplace.org>,
        "selinux@vger.kernel.org" <selinux@vger.kernel.org>,
        Jethro Beekman <jethro@fortanix.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>,
        "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>
Subject: Re: SGX vs LSM (Re: [PATCH v20 00/28] Intel SGX1 support)
Message-ID: <20190603210534.GF4894@linux.intel.com>
References: <CALCETrXXVMutX8eZk6nnkOAeS+Tj0sQd0FkW+wk6Rx8hQxCe6w@mail.gmail.com>
 <960B34DE67B9E140824F1DCDEC400C0F654E9824@ORSMSX116.amr.corp.intel.com>
 <20190528202407.GB13158@linux.intel.com>
 <285f279f-b500-27f0-ab42-fb1dbcc5ab18@tycho.nsa.gov>
 <960B34DE67B9E140824F1DCDEC400C0F654EB487@ORSMSX116.amr.corp.intel.com>
 <678a37af-797d-7bd5-a406-32548a270e3d@tycho.nsa.gov>
 <CALCETrWXB9fNNDH7gZxPTx05F78Og6K=ZtAr2aA++BDwY09Wbg@mail.gmail.com>
 <c1135352-0b5e-4694-b1a9-105876095877@tycho.nsa.gov>
 <CALCETrWsEXzUC33eJpGCpdMCBO4aYVviZLRD-CLMNaG5Jv-TCA@mail.gmail.com>
 <20190530180110.GB23930@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190530180110.GB23930@linux.intel.com>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, May 30, 2019 at 11:01:10AM -0700, Sean Christopherson wrote:
>   - Requires enclave builder to mark enclave pages executable in the
>     non-enclave VMAs, which may unnecessarily require EXECMOD on the
>     source file, or even worse, EXECMEM, and potentially increases the
>     attack surface since the file must be executable.

Enclave builder marks *non-enclave pages*? Not following.

> W^X handling:
>   - mmap() to /dev/sgx/enclave only allowed with PROT_NONE, i.e. force
>     userspace through mprotect() to simplify the kernel implementation.
>   - Add vm_ops mprotect() ops hook (I'll refer to SGX's implementation
>     as SGX.mprotect())
>   - Take explicit ALLOW_WRITE at ADD_REGION, a.k.a. EADD
>   - ADD_REGION also used to describe EAUG region (tentatively for SGX2).
>   - Track "can be written at some point in time (past or future)" as
>     ALLOW_WRITE (to avoid confusiong with MAY_WRITE).  A priori knowledge
>     of writability avoids having to track/coordinate PROT_WRITE across
>     VMAs and MMs.

Still not sure why you want to use vm_ops instead of file_operations.

The approach I've been proposing earlier in this email thread before
these new proposals can be summarized from hook perspective as:

- Allow mmap() only before ECREATE and require it to be size
  of the ELRANGE (ECREATE ioctl would check this). This would
  be with PROT_NONE.
- Disallow mprotect() before EINIT. Requires a new callback
  to file_operations like mmap() has.
- After EINIT check for each mprotect() that it matches the
  permissions of underlying enclave pages. Disallow mmap()
  after EINIT.

/Jarkko