On Thu, Jul 7, 2016 at 6:07 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote: > Hi, > > On Wed, Jul 06, 2016 at 03:25:23PM -0700, Kees Cook wrote: >> Enables CONFIG_HARDENED_USERCOPY checks on arm64. As done by KASAN in -next, >> renames the low-level functions to __arch_copy_*_user() so a static inline >> can do additional work before the copy. > > The checks themselves look fine, but as with the KASAN checks, it seems > a shame that this logic is duplicated per arch, integrated in subtly > different ways. > > Can we not __arch prefix all the arch uaccess helpers, and place > kasan_check_*() and check_object_size() calls in generic wrappers? > > If we're going to update all the arch uaccess helpers anyway, doing that > would make it easier to fix things up, or to add new checks in future. Yeah, I totally agree, and my work on the next step of this hardening will require something like this to separate the "check" logic from the "copy" logic, as I want to introduce a set of constant-sized copy_*_user helpers. Though currently x86 poses a weird problem in this regard (they have separate code paths for copy_* and __copy*, but I think it's actually a harmless(?) mistake. For now, I'd like to leave this as-is, and then do the copy_* cleanup, then do step 2 (slab whitelisting). -Kees -- Kees Cook Chrome OS & Brillo Security -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>