Date: Sat, 16 Apr 2016 21:58:09 +0200 From: Pavel Machek <pavel@...x.de> To: Emrah Demir <ed@...sec.com> Cc: Kees Cook <keescook@...omium.org>, 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>, 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 list <linux-pm@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>, kernel-hardening@...ts.openwall.com, keescook@...gle.com Subject: Re: [PATCH v2] kaslr: allow kASLR to be default over Hibernation On Fri 2016-04-15 12:25:19, Emrah Demir wrote: > On 2016-04-14 18:42, Kees Cook wrote: > >On Thu, Apr 14, 2016 at 1:34 PM, Pavel Machek <pavel@...x.de> wrote: > >>On Thu 2016-04-14 13:14:07, Kees Cook wrote: > >>>On Thu, Apr 14, 2016 at 1:01 PM, Pavel Machek <pavel@...x.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. > > >>>> > >>>> 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 what about making new kernel parameters. "hibernate" and "nohibernate" > > This way before decompression it will look at the parameters and depend on > parameters it will act differently > > "kaslr" "nohibernate" --> kASLR will enable, no hibernate > > "nokaslr" "nohibernate" --> Neither of them will work > > "kaslr" "hiberante" ---> Owner has to face consequences(ARM has > advantages) > > "nokaslr" "hibernate" ---> kASLR disabled and hibernate will works. > > Before writing something I want to know your ideas. Patch fixing hibernation with kaslr on x86 and x86-64 would be welcome. Adding command line options that will become useless when kernel is fixed ... not so much. Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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