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Re: rwx mapping between ex_table and rodata

From Ingo Molnar <mingo@kernel.org>
Newsgroups linux.kernel
Subject Re: rwx mapping between ex_table and rodata
Date 2015-09-25 09:30 +0200
Message-ID <qcvCa-32z-5@gated-at.bofh.it> (permalink)
References <qclt7-5sk-5@gated-at.bofh.it> <qclCO-5zE-9@gated-at.bofh.it> <qcnbz-7Zv-11@gated-at.bofh.it>
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* Kees Cook <keescook@chromium.org> wrote:

> On Thu, Sep 24, 2015 at 1:26 PM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
> > Hi,
> >
> > With the attached config and 4.3-rc2 on x86_64, I see the following in /sys/kernel/debug/kernel_page_tables:
> > ...
> > ---[ High Kernel Mapping ]---
> > 0xffffffff80000000-0xffffffff81000000          16M                               pmd
> > 0xffffffff81000000-0xffffffff81600000           6M     ro         PSE     GLB x  pmd
> > 0xffffffff81600000-0xffffffff81775000        1492K     ro                 GLB x  pte
> > 0xffffffff81775000-0xffffffff81800000         556K     RW                 GLB x  pte
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Btw., I think we should run this lookup automatically in late bootup, if 
CONFIG_X86_PTDUMP=y, and print a WARN()ing if there's any RWX permissions in the 
mappings.

That makes sure automated testing picks new bugs up.

Thanks,

	Ingo
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Re: rwx mapping between ex_table and rodata Kees Cook <keescook@chromium.org> - 2015-09-25 00:30 +0200
  Re: rwx mapping between ex_table and rodata Ingo Molnar <mingo@kernel.org> - 2015-09-25 09:30 +0200
  Re: rwx mapping between ex_table and rodata Ingo Molnar <mingo@kernel.org> - 2015-09-25 09:30 +0200
    Re: rwx mapping between ex_table and rodata Kees Cook <keescook@chromium.org> - 2015-09-26 18:50 +0200
    Re: rwx mapping between ex_table and rodata "H. Peter Anvin" <hpa@zytor.com> - 2015-09-28 23:20 +0200
      Re: rwx mapping between ex_table and rodata Kees Cook <keescook@chromium.org> - 2015-09-29 00:10 +0200
        Re: rwx mapping between ex_table and rodata "H. Peter Anvin" <hpa@zytor.com> - 2015-09-29 00:30 +0200
  Re: rwx mapping between ex_table and rodata Stephen Smalley <sds@tycho.nsa.gov> - 2015-09-28 16:20 +0200
    Re: rwx mapping between ex_table and rodata Kees Cook <keescook@chromium.org> - 2015-09-28 20:30 +0200
      Re: rwx mapping between ex_table and rodata Ingo Molnar <mingo@kernel.org> - 2015-10-01 09:20 +0200
      Re: rwx mapping between ex_table and rodata Thomas Gleixner <tglx@linutronix.de> - 2015-10-01 11:10 +0200
        Re: rwx mapping between ex_table and rodata Ingo Molnar <mingo@kernel.org> - 2015-10-01 11:20 +0200
          Re: rwx mapping between ex_table and rodata Kees Cook <keescook@chromium.org> - 2015-10-01 19:50 +0200
            Re: rwx mapping between ex_table and rodata Ingo Molnar <mingo@kernel.org> - 2015-10-02 09:20 +0200

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