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Date:   Fri, 21 Feb 2020 00:10:38 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     Jordan Hand <jorhand@linux.microsoft.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-sgx@vger.kernel.org, akpm@linux-foundation.org,
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        kai.svahn@intel.com, bp@alien8.de, josh@joshtriplett.org,
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        cedric.xing@intel.com, puiterwijk@redhat.com,
        linux-security-module@vger.kernel.org,
        Suresh Siddha <suresh.b.siddha@intel.com>,
        Haitao Huang <haitao.huang@linux.intel.com>
Subject: Re: [PATCH v26 10/22] x86/sgx: Linux Enclave Driver
Message-ID: <20200220221038.GA26618@linux.intel.com>
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On Tue, Feb 18, 2020 at 07:26:31PM -0800, Jordan Hand wrote:
> 	if (!page || (~page->vm_max_prot_bits & vm_prot_bits))
> 		return -EACCESS
> 
> This means that for any process where READ_IMPLIES_EXECUTE is set and
> page where (vma->vm_flags & VM_MAYEXEC) == true, mmap/mprotect calls to
> that request PROT_READ on a page that was not added with PROT_EXEC will
> fail.

Right. You would end up requesting RX from a R region.

And you are suggesting that we tweak it along the lines of to make RIE
processes work:

unsigned long max_prot_bits = page->vm_max_prot_bits;

if (!!(current->personality & READ_IMPLIES_EXEC) &&
    vma->vm_flags & VM_MAY_EXEC)
    max_prot_bits |= VM_EXEC;

/* ... */

if (!page || (~max_prot_bits & vm_prot_bits))
	return -EACCESS

?

/Jarkko