Re: [PATCH 0/2] Support for set_memory_* outside of module space

Kees Cook
2015-11-03T23:42:47Z

On Tue, Nov 3, 2015 at 1:48 PM, Laura Abbott <labbott@fedoraproject.org> wrote:
>
> Hi,
>
> Based on a recent discussion[1] there is interest in having set_memory_* work
> on kernel memory for security and other use cases. This patch adds the
> ability for that to happen behind a kernel option. If this is welcome enough,
> the Kconfig can be dropped. This has been briefly tested but not stress tested.
>
> Thanks,
> Laura
>
> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-October/382079.html
>
> Laura Abbott (2):
> arm64: Get existing page protections in split_pmd
> arm64: Allow changing of attributes outside of modules
>
> arch/arm64/Kconfig.debug | 11 +++++++
> arch/arm64/mm/mm.h | 3 ++
> arch/arm64/mm/mmu.c | 11 ++++---
> arch/arm64/mm/pageattr.c | 74 ++++++++++++++++++++++++++++++++++++++++++++----
> 4 files changed, 88 insertions(+), 11 deletions(-)

This seems like the right thing to have. What's arm64 doing for the
equivalent of x86 and arm's set_kernel_text_* functions? x86 and arm
call their set_memory_* functions, for example. A quick examination
shows mm/mmu.c is just doing it "by hand" in fixup_executable and
mark_rodata_ro? Could those functions use the new set_memory_* ones?

-Kees

--
Kees Cook
Chrome OS Security