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Date: Wed, 5 Oct 2016 22:23:08 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: kernel-hardening@...ts.openwall.com
Cc: Kees Cook <keescook@...omium.org>,
	Laura Abbott <labbott@...oraproject.org>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: initcall randomization

On Wed, Oct 05, 2016 at 06:09:01PM +0100, Ard Biesheuvel wrote:
> Did anyone ever look into whether there is anything to gain in terms
> of hardening from randomizing the order initcalls are issued at each
> level? I know entropy is hard to come by at this stage, but on recent
> UEFI systems, this is something we could potentially solve
> generically. (It may uncover some breakage as well, but only hidden
> breakage that could already surface at any time due to linker changes,
> so I think this could serve as a diagnostic option as well)

We rely on link-order init call dependancy in the kernel a lot, so be
very careful about reording them.

> Since boot time mappings are often performed in initcalls, this could
> potentially reduce the predictability of the layout of the virtual
> kernel space. But before I start experimenting with this, I thought
> I'd ask if anyone has ever looked into this.

I think you will break things, try it yourself and see :)

good luck!

greg k-h

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