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Date:   Thu, 22 Aug 2019 07:27:50 -0700
From:   Sean Christopherson <sean.j.christopherson@intel.com>
To:     "Ayoun, Serge" <serge.ayoun@intel.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        "linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>
Subject: Re: [PATCH 4/5] x86/sgx: Validate TCS permssions in
 sgx_validate_secinfo()
Message-ID: <20190822142750.GC25467@linux.intel.com>
References: <20190819152544.7296-1-jarkko.sakkinen@linux.intel.com>
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On Thu, Aug 22, 2019 at 04:33:35AM -0700, Ayoun, Serge wrote:
> Sean is right that never mind the value in secsinfo->flags, HW will reset RWX
> For TCS pages.  So basically you may not enforce and and could not check
> those but... The signature depends On those flags, so if you put a non-zero
> flag value, eadd will pass but if you compute the signature according to this
> non zero value then you will have a delta between ur signature and HW's
> signature: einit will fail.  So this is tricky and more a usability issue.  I
> vote for checking the flag is zeroed.

Ugh, didn't think about that behavior.  That's obnoxious.  Adding the
check makes sense in that case.