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Date:   Mon, 10 Jun 2019 18:27:17 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Cedric Xing <cedric.xing@intel.com>,
        Stephen Smalley <sds@tycho.nsa.gov>,
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        Eric Paris <eparis@parisplace.org>, selinux@vger.kernel.org,
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Subject: Re: [RFC PATCH v2 2/5] x86/sgx: Require userspace to define enclave
 pages' protection bits
Message-ID: <20190610152717.GB3752@linux.intel.com>
References: <20190606021145.12604-1-sean.j.christopherson@intel.com>
 <20190606021145.12604-3-sean.j.christopherson@intel.com>
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On Wed, Jun 05, 2019 at 07:11:42PM -0700, Sean Christopherson wrote:
> [SNAP]

Same general criticism as for the previous patch: try to say things as
they are without anything extra.

> A third alternative would be to pull the protection bits from the page's
> SECINFO, i.e. make decisions based on the protections enforced by
> hardware.  However, with SGX2, userspace can extend the hardware-
> enforced protections via ENCLU[EMODPE], e.g. can add a page as RW and
> later convert it to RX.  With SGX2, making a decision based on the
> initial protections would either create a security hole or force SGX to
> dynamically track "dirty" pages (see first alternative above).
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>

'flags' should would renamed as 'secinfo_flags_mask' even if the name is
longish. It would use the same values as the SECINFO flags. The field in
struct sgx_encl_page should have the same name. That would express
exactly relation between SECINFO and the new field. I would have never
asked on last iteration why SECINFO is not enough with a better naming.

The same field can be also used to cage page type to a subset of values.

/Jarkko