Date: Fri, 15 Apr 2016 12:25:19 -0400 From: Emrah Demir <ed@...sec.com> To: Kees Cook <keescook@...omium.org> Cc: Pavel Machek <pavel@...x.de>, 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 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. -Emrah
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