On Thu, Apr 18, 2019 at 12:55 AM Alex Ghiti <alex@xxxxxxxx> wrote: > Regarding the help text, I agree that it does not seem to be frequent to > place > comment above config like that, I'll let Christoph and you decide what's > best. And I'll > add the possibility for the arch to define its own STACK_RND_MASK. Yeah, I think it's very helpful to spell out the requirements for new architectures with these kinds of features in the help text (see SECCOMP_FILTER for example). > > I think CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT should select > > CONFIG_ARCH_HAS_ELF_RANDOMIZE. It would mean moving > > > I don't think we should link those 2 features together: an architecture > may want > topdown mmap and don't care about randomization right ? Given that the mmap randomization and stack randomization are already coming along for the ride, it seems weird to make brk randomization an optional feature (especially since all the of the architectures you're converting include it). I'd also like these kinds of security features to be available by default. So, I think one patch to adjust the MIPS brk randomization entropy and then you can just include it in this move. > Actually, I had to add those ifdefs for mmap_rnd_compat_bits, not > is_compat_task. Oh! In that case, use CONFIG_HAVE_ARCH_MMAP_RND_BITS. :) Actually, what would be maybe cleaner would be to add mmap_rnd_bits_min/max consts set to 0 for the non-CONFIG_HAVE_ARCH_MMAP_RND_BITS case at the top of mm/mmap.c. I really like this clean-up! I think we can move x86 to it too without too much pain. :) -- Kees Cook
