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Message-ID: <20150925061523.GA15753@gmail.com> Date: Fri, 25 Sep 2015 08:15:23 +0200 From: Ingo Molnar <mingo@...nel.org> To: Dave Hansen <dave@...1.net> Cc: x86@...nel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, Linus Torvalds <torvalds@...ux-foundation.org>, Andrew Morton <akpm@...ux-foundation.org>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...en8.de>, Kees Cook <keescook@...gle.com> Subject: Re: [PATCH 26/26] x86, pkeys: Documentation * Dave Hansen <dave@...1.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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