linux-kernel - Re: [PATCH] hardening: add PROT_FINAL prot flag to mmap/mprotect

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Date:	Tue, 2 Oct 2012 15:10:56 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Ard Biesheuvel <ard.biesheuvel@...il.com>
Cc:	linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	James Morris <jmorris@...ei.org>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	linux-mm@...ck.org
Subject: Re: [PATCH] hardening: add PROT_FINAL prot flag to mmap/mprotect

On Tue, Oct 2, 2012 at 2:41 PM, Ard Biesheuvel <ard.biesheuvel@...il.com> wrote:
> 2012/10/2 Kees Cook <keescook@...omium.org>:
>>> If desired, additional restrictions can be imposed by using the
>>> security framework, e.g,, disallow non-final r-x mappings.
>>
>> Interesting; what kind of interface did you have in mind?
>
> The 'interface' we use is a LSM .ko which registers handlers for
> mmap() and mprotect() that fail the respective invocations if the
> passed arguments do not adhere to the policy.

Seems reasonable.

>>>> It seems like there needs to be a sensible way to detect that this flag is
>>>> available, though.
>>>
>>> I am open for suggestions to address this. Our particular
>>> implementation of the loader (on an embedded system) tries to set it
>>> on the first mmap invocation, and stops trying if it fails. Not the
>>> most elegant approach, I know ...
>>
>> Actually, that seems easiest.
>>
>> Has there been any more progress on this patch over-all?
>
> No progress.

Al, Andrew, anyone? Thoughts on this?
(First email is https://lkml.org/lkml/2012/8/14/448)

-Kees

-- 
Kees Cook
Chrome OS Security
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