Messages in this thread | | | Date | Fri, 25 Sep 2015 08:15:23 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 26/26] x86, pkeys: Documentation |
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* Dave Hansen <dave@sr71.net> wrote:
> > I.e. AFAICS pkeys could be used to create true '--x' permissions for executable > > (user-space) pages. > > Just remember that all of the protections are dependent on the contents of PKRU. > If an attacker controls the Access-Disable bit in PKRU for the executable-only > region, you're sunk.
The same is true if the attacker can execute mprotect() calls.
> But, that either requires being able to construct and execute arbitrary code > *or* call existing code that sets PKRU to the desired values. Which, I guess, > gets harder to do if all of the the wrpkru's are *in* the execute-only area.
Exactly. True --x executable regions makes it harder to 'upgrade' limited attacks.
Thanks,
Ingo
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