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Date:   Tue, 15 Feb 2022 08:07:33 -0800
From:   Kees Cook <keescook@chromium.org>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Andrew Morton <akpm@linux-foundation.org>,
        "James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
        Helge Deller <deller@gmx.de>, Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-ia64@vger.kernel.org, linux-parisc@vger.kernel.org,
        linux-arch@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v4 00/13] Fix LKDTM for PPC64/IA64/PARISC v4
Message-ID: <202202150807.D584917D34@keescook>
References: <cover.1644928018.git.christophe.leroy@csgroup.eu>
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On Tue, Feb 15, 2022 at 01:40:55PM +0100, Christophe Leroy wrote:
> PPC64/IA64/PARISC have function descriptors. LKDTM doesn't work
> on those three architectures because LKDTM messes up function
> descriptors with functions.
> 
> This series does some cleanup in the three architectures and
> refactors function descriptors so that it can then easily use it
> in a generic way in LKDTM.

Thanks for doing this! It looks good to me. :)

-Kees

> 
> Changes in v4:
> - Added patch 1 which Fixes 'sparse' for powerpc64le after wrong report on previous series, refer https://github.com/ruscur/linux-ci/actions/runs/1351427671
> - Exported dereference_function_descriptor() to modules
> - Addressed other received comments
> - Rebased on latest powerpc/next (5a72345e6a78120368fcc841b570331b6c5a50da)
> 
> Changes in v3:
> - Addressed received comments
> - Swapped some of the powerpc patches to keep func_descr_t renamed as struct func_desc and remove 'struct ppc64_opd_entry'
> - Changed HAVE_FUNCTION_DESCRIPTORS macro to a config item CONFIG_HAVE_FUNCTION_DESCRIPTORS
> - Dropped patch 11 ("Fix lkdtm_EXEC_RODATA()")
> 
> Changes in v2:
> - Addressed received comments
> - Moved dereference_[kernel]_function_descriptor() out of line
> - Added patches to remove func_descr_t and func_desc_t in powerpc
> - Using func_desc_t instead of funct_descr_t
> - Renamed HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR to HAVE_FUNCTION_DESCRIPTORS
> - Added a new lkdtm test to check protection of function descriptors
> 
> Christophe Leroy (13):
>   powerpc: Fix 'sparse' checking on PPC64le
>   powerpc: Move and rename func_descr_t
>   powerpc: Use 'struct func_desc' instead of 'struct ppc64_opd_entry'
>   powerpc: Remove 'struct ppc64_opd_entry'
>   powerpc: Prepare func_desc_t for refactorisation
>   ia64: Rename 'ip' to 'addr' in 'struct fdesc'
>   asm-generic: Define CONFIG_HAVE_FUNCTION_DESCRIPTORS
>   asm-generic: Define 'func_desc_t' to commonly describe function
>     descriptors
>   asm-generic: Refactor dereference_[kernel]_function_descriptor()
>   lkdtm: Force do_nothing() out of line
>   lkdtm: Really write into kernel text in WRITE_KERN
>   lkdtm: Fix execute_[user]_location()
>   lkdtm: Add a test for function descriptors protection
> 
>  arch/Kconfig                             |  3 +
>  arch/ia64/Kconfig                        |  1 +
>  arch/ia64/include/asm/elf.h              |  2 +-
>  arch/ia64/include/asm/sections.h         | 24 +-------
>  arch/ia64/kernel/module.c                |  6 +-
>  arch/parisc/Kconfig                      |  1 +
>  arch/parisc/include/asm/sections.h       | 16 ++----
>  arch/parisc/kernel/process.c             | 21 -------
>  arch/powerpc/Kconfig                     |  1 +
>  arch/powerpc/Makefile                    |  2 +-
>  arch/powerpc/include/asm/code-patching.h |  2 +-
>  arch/powerpc/include/asm/elf.h           |  6 ++
>  arch/powerpc/include/asm/sections.h      | 29 ++--------
>  arch/powerpc/include/asm/types.h         |  6 --
>  arch/powerpc/include/uapi/asm/elf.h      |  8 ---
>  arch/powerpc/kernel/module_64.c          | 42 ++++++--------
>  arch/powerpc/kernel/ptrace/ptrace.c      |  6 ++
>  arch/powerpc/kernel/signal_64.c          |  8 +--
>  drivers/misc/lkdtm/core.c                |  1 +
>  drivers/misc/lkdtm/lkdtm.h               |  1 +
>  drivers/misc/lkdtm/perms.c               | 71 +++++++++++++++++++-----
>  include/asm-generic/sections.h           | 15 ++++-
>  include/linux/kallsyms.h                 |  2 +-
>  kernel/extable.c                         | 24 +++++++-
>  tools/testing/selftests/lkdtm/tests.txt  |  1 +
>  25 files changed, 155 insertions(+), 144 deletions(-)
> 
> -- 
> 2.34.1
> 

-- 
Kees Cook