Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <1526537830-22606-24-git-send-email-yamada.masahiro@socionext.com>
References: <1526537830-22606-1-git-send-email-yamada.masahiro@socionext.com> <1526537830-22606-24-git-send-email-yamada.masahiro@socionext.com>
From:   Kees Cook <keescook@chromium.org>
Date:   Wed, 16 May 2018 23:26:20 -0700
Message-ID: <CAGXu5jKhZWMfKWvj2QhU8LaXD4CqO9oVZ==Ux919jN7fKG8okg@mail.gmail.com>
Subject: Re: [PATCH v4 23/31] stack-protector: test compiler capability in
 Kconfig and drop AUTO mode
To:     Masahiro Yamada <yamada.masahiro@socionext.com>
Cc:     linux-kbuild <linux-kbuild@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Ulf Magnusson <ulfalizer@gmail.com>,
        "Luis R . Rodriguez" <mcgrof@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Emese Revfy <re.emese@gmail.com>, X86 ML <x86@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, May 16, 2018 at 11:17 PM, Masahiro Yamada
<yamada.masahiro@socionext.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@socionext.com>

Thanks!

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

-Kees

-- 
Kees Cook
Pixel Security