On Thu, Jan 19, 2017 at 2:56 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote: > Hi Laura, > > On Wed, Jan 18, 2017 at 05:29:05PM -0800, Laura Abbott wrote: >> diff --git a/security/Kconfig b/security/Kconfig >> index 118f454..ad6ce82 100644 >> --- a/security/Kconfig >> +++ b/security/Kconfig >> @@ -158,6 +158,22 @@ config HARDENED_USERCOPY_PAGESPAN >> been removed. This config is intended to be used only while >> trying to find such users. >> >> +config ARCH_HAS_HARDENED_MAPPINGS >> + def_bool n >> + >> +config HARDENED_PAGE_MAPPINGS >> + bool "Mark kernel mappings with stricter permissions (RO/W^X)" >> + default y >> + depends on ARCH_HAS_HARDENED_MAPPINGS >> + help >> + If this is set, kernel text and rodata memory will be made read-only, >> + and non-text memory will be made non-executable. This provides >> + protection against certain security attacks (e.g. executing the heap >> + or modifying text). >> + >> + Unless your system has known restrictions or performance issues, it >> + is recommended to say Y here. > > It's somewhat unfortunate that this means the feature is no longer > mandatory on arm64 (and s390+x86). We have a boot-time switch to turn > the protections off, so I was hoping we could make this mandatory on all > architectures with support. Oh, I totally missed this. Yes, we need it to stay mandatory. It should be possible by just adding "select HARDENED_PAGE_MAPPINGS" to the arch Kconfig, yes? > It would be good to see if we could make this mandatory for arm and > parisc, or if it really needs to be optional for either of those. (Adding mpe to CC...) Michael, what's needed to get this working on powerpc too? -Kees -- Kees Cook Nexus Security -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
