linux-kernel - Re: [PATCH v2] kaslr: allow kASLR to be default over Hibernation

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Message-ID: <20160414200102.GB3856@amd>
Date:	Thu, 14 Apr 2016 22:01:02 +0200
From:	Pavel Machek <pavel@...x.de>
To:	Kees Cook <keescook@...omium.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	James Morse <james.morse@....com>,
	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, Len Brown <len.brown@...el.com>,
	Borislav Petkov <bp@...e.de>,
	Andy Lutomirski <luto@...nel.org>, linux-doc@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v2] kaslr: allow kASLR to be default over Hibernation

Hi!

> Since kASLR and Hibernation can not currently coexist at runtime
> on x86, the default behavior was to disable kASLR by default when
> CONFIG_HIBERNATION was present (to retain original behavior).
> 
> The behavior of kASLR on arm64 (and soon MIPS) is to be enabled by
> default when selected at build time. Since arm64 Hibernation does not
> conflict with kASLR, this fixes the hibernation argument parsing to be
> x86-specific. Additionally, since end users want to be able to select
> kASLR on x86 by default at build time, create CONFIG_RANDOMIZE_BASE_ON
> that is present only on x86.
> 
> Signed-off-by: Kees Cook <keescook@...omium.org>

I believe this is bad idea. arm64 shows that kaslr and hibernation can
coexist, and hibernation is still useful when your battery runs out.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html