On Wed, Nov 4, 2015 at 10:51 AM, Laura Abbott <labb...@redhat.com> wrote: > On 11/03/2015 03:42 PM, Kees Cook wrote: >> >> On Tue, Nov 3, 2015 at 1:48 PM, Laura Abbott <labb...@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? >> > > It looks like mark_rodata_ro could probably use the set_memory_ro. I'll > have to test it out. Longer term, the page table setup code should > probably just be pulled out into a common file. > > Do you know the code path in ftrace which would trigger the > set_kernel_text_* > If not, I'll go see if I can figure out if it's implemented yet on arm64.
Looking now, it seems that things like jump label use aarch64_insn_patch_text, which ultimately call down to __aarch64_insn_write(), which is using the fixmap via FIX_TEXT_POKE0. -Kees -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/