linux-kernel - Re: [PATCH v4 23/31] stack-protector: test compiler capability in Kconfig and drop AUTO mode

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Message-ID: <CAGXu5jKhZWMfKWvj2QhU8LaXD4CqO9oVZ==Ux919jN7fKG8okg@mail.gmail.com>
Date:   Wed, 16 May 2018 23:26:20 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     linux-kbuild <linux-kbuild@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Ulf Magnusson <ulfalizer@...il.com>,
        "Luis R . Rodriguez" <mcgrof@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Emese Revfy <re.emese@...il.com>, X86 ML <x86@...nel.org>
Subject: Re: [PATCH v4 23/31] stack-protector: test compiler capability in
 Kconfig and drop AUTO mode

On Wed, May 16, 2018 at 11:17 PM, Masahiro Yamada
<yamada.masahiro@...ionext.com> wrote:
> Move the test for -fstack-protector(-strong) option to Kconfig.
>
> If the compiler does not support the option, the corresponding menu
> is automatically hidden.  If STRONG is not supported, it will fall
> back to REGULAR.  If REGULAR is not supported, it will be disabled.
> This means, AUTO is implicitly handled by the dependency solver of
> Kconfig, hence removed.
>
> I also turned the 'choice' into only two boolean symbols.  The use of
> 'choice' is not a good idea here, because all of all{yes,mod,no}config
> would choose the first visible value, while we want allnoconfig to
> disable as many features as possible.
>
> X86 has additional shell scripts in case the compiler supports those
> options, but generates broken code.  I added CC_HAS_SANE_STACKPROTECTOR
> to test this.  I had to add -m32 to gcc-x86_32-has-stack-protector.sh
> to make it work correctly.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>

Thanks!

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

-- 
Kees Cook
Pixel Security