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SubjectRe: [PATCH] powerpc: Default to enabling STRICT_KERNEL_RWX
On Thu, Oct 5, 2017 at 12:49 AM, Christophe LEROY
<christophe.leroy@c-s.fr> wrote:
>
>
> Le 05/10/2017 à 05:45, Kees Cook a écrit :
>>
>> When available, CONFIG_KERNEL_RWX should be default-enabled.
>
>
> On PPC32, this option implies deactivating BATs and/or LTLB mapping of the
> linear kernel address space, hence a significant performance degradation.
>
> So at least on PPC32, it should remain unselected by default.

Alright, sounds fine to me. Would this be okay?

+ select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if !PPC64

-Kees

>
> Christophe
>
>
>>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: linuxppc-dev@lists.ozlabs.org
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>> ---
>> arch/powerpc/Kconfig | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index 809c468edab1..9a549bbfc278 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -178,6 +178,7 @@ config PPC
>> select HAVE_ARCH_TRACEHOOK
>> select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 ||
>> PPC32) && !RELOCATABLE && !HIBERNATION)
>> select ARCH_OPTIONAL_KERNEL_RWX if
>> ARCH_HAS_STRICT_KERNEL_RWX
>> + select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
>> select HAVE_CBPF_JIT if !PPC64
>> select HAVE_CONTEXT_TRACKING if PPC64
>> select HAVE_DEBUG_KMEMLEAK
>>
>



--
Kees Cook
Pixel Security

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