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

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Date:	Wed, 6 Apr 2016 23:56:38 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
Cc:	Kees Cook <keescook@...omium.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, "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
Subject: Re: [PATCH] Prefer kASLR over Hibernation


* Rafael J. Wysocki <rafael@...nel.org> wrote:

> On Wed, Apr 6, 2016 at 9:44 PM, Kees Cook <keescook@...omium.org> wrote:
> > When building with both CONFIG_HIBERNATION and CONFIG_RANDOMIZE_BASE,
> > one or the other must be chosen at boot-time. Until now, hibernation
> > was selected when no choice was made on the command line.
> >
> > To make the security benefits of kASLR more widely available to end
> > users (since the use of hibernation is becoming more rare and kASLR,
> > already available on x86, will be available on arm64 and MIPS soon),
> > this changes the default to preferring kASLR over hibernation. Users
> > wanting hibernation can turn off kASLR by adding "nokaslr" to the kernel
> > command line.
> >
> > Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> > Signed-off-by: Kees Cook <keescook@...omium.org>
> 
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Or do you want me to apply it?

I don't think this is a good idea, as it turns off emergency hibernation of 
laptops - many desktop distros support it by default.

Thanks,

	Ingo