kernel-hardening - Re: Re: [RFC PATCH 1/4] security: mark LSM hooks as __ro_after

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Message-ID: <20170213175730.GA16636@leverpostej>
Date: Mon, 13 Feb 2017 17:57:30 +0000
From: Mark Rutland <mark.rutland@....com>
To: Kees Cook <keescook@...omium.org>
Cc: Laura Abbott <labbott@...hat.com>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	James Morris <jmorris@...ei.org>,
	linux-security-module <linux-security-module@...r.kernel.org>,
	"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>
Subject: Re: Re: [RFC PATCH 1/4] security: mark LSM hooks
 as __ro_after_init

Hi,

On Mon, Feb 13, 2017 at 09:34:32AM -0800, Kees Cook wrote:
> On Mon, Feb 13, 2017 at 8:26 AM, Laura Abbott <labbott@...hat.com> wrote:
> > On 02/13/2017 06:59 AM, Kees Cook wrote:
> >> On Mon, Feb 13, 2017 at 2:33 AM, Tetsuo Handa
> >> <penguin-kernel@...ove.sakura.ne.jp> wrote:
> >>> James Morris wrote:
> >>>> As the regsitration of LSMs is performed during init and then does
> >>>> not change, we can mark all of the regsitration hooks as __ro_after_init.
> >>>>
> >>>> Signed-off-by: James Morris <james.l.morris@...cle.com>
> >>>
> >>> This patch makes LKM based LSMs (e.g. AKARI) impossible.
> >>> I'm not happy with this patch.
> >>
> >> LKM based LSMs don't exist yet, and when they do, we may also have the
> >> "write rarely" infrastructure done, which LKM based LSMs can use to
> >> update the structures.
> >
> > Is someone actually working on the write rarely patches? If a version
> > has been sent out, I don't recall seeing it.
> 
> Still mostly just discussion. I've been toying with the PaX-style of
> it on x86, and I think Mark Rutland had some ideas for arm64, but I
> don't know if he's actually written code.

While I had a rough idea [1] of what that could look like, I haven't
written any code.

Thanks,
Mark.

[1] http://www.openwall.com/lists/kernel-hardening/2016/11/18/3

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