linux-kernel - Re: [PATCH] powerpc: Default to enabling STRICT_KERNEL

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Message-ID: <CAGXu5jJ-Hn9cEsHzW2LcshcnWAnrMJCwBN4aw9WSD4y6S+nBJQ@mail.gmail.com>
Date:   Thu, 5 Oct 2017 11:58:44 -0700
From:   Kees Cook <keescook@...omium.org>
To:     christophe leroy <christophe.leroy@....fr>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Paul Mackerras <paulus@...ba.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH] powerpc: Default to enabling STRICT_KERNEL_RWX

On Thu, Oct 5, 2017 at 11:57 AM, christophe leroy
<christophe.leroy@....fr> wrote:
>
>
> Le 05/10/2017 à 19:30, Kees Cook a écrit :
>>
>> On Thu, Oct 5, 2017 at 12:49 AM, Christophe LEROY
>> <christophe.leroy@....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
>
>
> You mean
>
> select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if PPC64
>
> Don't you ?

Oops, yes! :)

-Kees

-- 
Kees Cook
Pixel Security