Re: [PATCH 31/32] x86, pkeys: execute-only support

From	Andy Lutomirski <luto@amacapital.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH 31/32] x86, pkeys: execute-only support
Date	2015-12-15 00:50 +0100
Message-ID	<qFL2q-4xi-19@gated-at.bofh.it> (permalink)
References	(1 earlier) <qFGFs-1Ro-25@gated-at.bofh.it> <qFHBw-2sR-11@gated-at.bofh.it> <qFKSJ-4sB-11@gated-at.bofh.it> <qFKSL-4sB-47@gated-at.bofh.it> <qFL2q-4xi-9@gated-at.bofh.it>
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On Mon, Dec 14, 2015 at 3:44 PM, Dave Hansen <dave@sr71.net> wrote:
> On 12/14/2015 03:39 PM, Andy Lutomirski wrote:
>>> > Nope.  My linker-fu is weak.
>>> >
>>> > Can we even depend on the linker by itself?  Even if the sections were
>>> > marked --x, we can't actually use them with those permissions unless we
>>> > have protection keys.
>>> >
>>> > Do we need some special tag on the section to tell the linker to map it
>>> > as --x under some conditions and r-x for others?
>>> >
>> Why?  Wouldn't --x just end up acting like r-x if PKRU is absent?
>
> An app doing --x would expect it to be unreadable.  I don't think we can
> just silently turn it in to r-x.

I don't see why.  After all, an app doing --x right now gets rx.  An
app doing r-- still gets r-x on some systems.

--Andy


-- 
Andy Lutomirski
AMA Capital Management, LLC
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Thread

[PATCH 31/32] x86, pkeys: execute-only support Dave Hansen <dave@sr71.net> - 2015-12-14 20:10 +0100
  Re: [PATCH 31/32] x86, pkeys: execute-only support Kees Cook <keescook@google.com> - 2015-12-14 21:10 +0100
    Re: [PATCH 31/32] x86, pkeys: execute-only support Kees Cook <keescook@google.com> - 2015-12-15 00:40 +0100
    Re: [PATCH 31/32] x86, pkeys: execute-only support Dave Hansen <dave@sr71.net> - 2015-12-15 00:40 +0100
      Re: [PATCH 31/32] x86, pkeys: execute-only support Andy Lutomirski <luto@amacapital.net> - 2015-12-15 00:40 +0100
        Re: [PATCH 31/32] x86, pkeys: execute-only support Kees Cook <keescook@google.com> - 2015-12-15 00:50 +0100
        Re: [PATCH 31/32] x86, pkeys: execute-only support Dave Hansen <dave@sr71.net> - 2015-12-15 00:50 +0100
          Re: [PATCH 31/32] x86, pkeys: execute-only support Andy Lutomirski <luto@amacapital.net> - 2015-12-15 00:50 +0100
            Re: [PATCH 31/32] x86, pkeys: execute-only support Dave Hansen <dave@sr71.net> - 2015-12-15 01:30 +0100

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