linux-kernel - Re: [PATCH] lkdtm: support llvm-objcopy

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Message-ID: <CAKwvOdmOZZxZYCeVzJbdMMdstsvquXEWpUvPsxVtXVQqi2q_Eg@mail.gmail.com>
Date:   Mon, 13 May 2019 15:26:06 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     clang-built-linux <clang-built-linux@...glegroups.com>,
        Nathan Chancellor <nathanchance@...il.com>,
        Jordan Rupprect <rupprecht@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] lkdtm: support llvm-objcopy

On Mon, May 13, 2019 at 3:21 PM Nick Desaulniers
<ndesaulniers@...gle.com> wrote:
>
> With CONFIG_LKDTM=y and make OBJCOPY=llvm-objcopy, llvm-objcopy errors:
> llvm-objcopy: error: --set-section-flags=.text conflicts with
> --rename-section=.text=.rodata
>
> Rather than support setting flags then renaming sections vs renaming
> then setting flags, it's simpler to just change both at the same time
> via --rename-section.
>
> This can be verified with:
> $ readelf -S drivers/misc/lkdtm/rodata_objcopy.o
> ...
> Section Headers:
>   [Nr] Name              Type             Address           Offset
>        Size              EntSize          Flags  Link  Info  Align
> ...
>   [ 1] .rodata           PROGBITS         0000000000000000  00000040
>        0000000000000004  0000000000000000   A       0     0     4
> ...
>
> Which shows in the Flags field that .text is now renamed .rodata, the
> append flag A is set, and the section is not flagged as writeable W.

Probably should've been:
Which shows that .text is now renamed .rodata, the
append flag A is set, and the section is not flagged as writeable W.

-- 
Thanks,
~Nick Desaulniers