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

[Pavel Machek <pavel@denx.de>]

On Thu 2016-04-14 13:14:07, Kees Cook wrote:
> On Thu, Apr 14, 2016 at 1:01 PM, Pavel Machek <pavel@denx.de> wrote:
> > 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@chromium.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.
> 
> What? I'm confused -- this patch leaves the x86 behavior as-is by
> default but allows hibernation to work with arm64. (For example, right
> now, if you boot arm64 with "kaslr" kernel argument, hibernation will
> get needlessly disabled.)

So it is very different from the PATCH v1, still it shares the
subject?

This is the part I don't like:

> >> 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).

Now I notice that it is quite unclear if it actually changes
anything...

								Pavel
-- 
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