Now that's nice. dillon@ just committed a fix that enables the NX bit for read mappings by default. And the suggestion comes from Theo.

Seems that also has some good aspects.

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@_xhr_ How does NX relate to Spectre?

Also seems like PaX NOEXEC is a more complete solution. PaX NOEXEC has two parts:

1. PaX PAGEEXEC: Disallow mmap(RWX)
2. PaX MPROTECT: Disallow mprotect(W -> X) and mprotect(X -> W)

DFBSD's implementation is rather... meh


@_xhr_ Seems like I might've misinterpreted the commit. This is just the hardware side, flipping bits to support NX. Is that correct?


@lattera Yep, correct.

I didn't want to say that this commit is related to Spectre. I wanted to say that the actions initiated by Spectre/Meltdown brought the BSDs more closer together. I cannot remember any commit by dillion@ where he referenced Theo.


@_xhr_ Gotcha.

I hope DFBSD adopts PaX NOEXEC. They will need a way to toggle PaX PAGEEXEC and PaX MPROTECT on a per-application basis if so.

We already have both PaX PAGEEXEC and the toggles in #HardenedBSD. Feel free to reach out if you have any questions and I'd be glad to give non-xkcd pointers. ;)


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