kernel-hardening - Re: [PATCH] Prefer kASLR over Hibernation

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Date: Thu, 7 Apr 2016 02:05:43 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Kees Cook <keescook@...omium.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Matt Redfearn <matt.redfearn@...tec.com>,
	Yves-Alexis Perez <corsac@...ian.org>, Emrah Demir <ed@...sec.com>,
	Jonathan Corbet <corbet@....net>, "x86@...nel.org" <x86@...nel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	Borislav Petkov <bp@...e.de>, Andy Lutomirski <luto@...nel.org>,
	"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH] Prefer kASLR over Hibernation


* Kees Cook <keescook@...omium.org> wrote:

> >> I don't think this is a good idea, as it turns off emergency hibernation of 
> >> laptops - many desktop distros support it by default.
> >
> > Right, I forgot about this one.
> 
> When I last checked Ubuntu doesn't enable hibernation by default any more: 
> https://help.ubuntu.com/16.04/ubuntu-help/power-hibernate.html
> 
> And it seems like Fedora either doesn't either, or has a lot of people
> for whom it doesn't work:
> https://bugzilla.redhat.com/show_bug.cgi?id=1206936
> https://bugzilla.redhat.com/show_bug.cgi?id=1224151
> http://blog.kriptonium.com/2015/12/fedora-23-hibernate.html

Ok, that's a relatively recent development, I distinctly remember my laptop being 
hibernated in such a fashion fairly recently.

That makes it easier to hack around the kASLR incompatibility by making 
hibernation less useful. Personally I think that conceptually user space 
persistency (CRIU et al) is superior to kernel level hibernation - but
user-space save/restore is nowhere near as complete as kernel hibernation,
so it's still somewhat sad that it doesn't work ...

Thanks,

	Ingo

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