Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory

From	Andy Lutomirski <luto@amacapital.net>
Newsgroups	linux.kernel
Subject	Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory
Date	2015-11-30 22:40 +0100
Message-ID	<qAEkW-yr-15@gated-at.bofh.it> (permalink)
References	(7 earlier) <qzxvb-7sb-1@gated-at.bofh.it> <qzxvc-7sb-3@gated-at.bofh.it> <qA5dv-3H7-3@gated-at.bofh.it> <qAE1A-r5-21@gated-at.bofh.it> <qAEkW-yr-17@gated-at.bofh.it>
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On Mon, Nov 30, 2015 at 1:33 PM, Kees Cook <keescook@chromium.org> wrote:
> On Mon, Nov 30, 2015 at 1:14 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>> On 11/29/15 00:05, Ingo Molnar wrote:
>>>
>>> * Andy Lutomirski <luto@amacapital.net> wrote:
>>>
>>>>>>  - print a warning and a backtrace, and just mark the page read-write
>>>>>> so that the machine survives, but we get notified and can fix whatever
>>>>>> broken code
>>>>>
>>>>> This seems very easy to add. Should I basically reverse the effects of
>>>>> mark_rodata_ro(), or should I only make the new ro-after-init section as RW?
>>>>> (I think the former would be easier.)
>>>>
>>>> I'd suggest verifying that the page in question is .data..ro_after_init and, if
>>>> so, marking that one page RW.
>>>
>>> Yes, this was PaX's suggestion as well, and I agree: doing that turns a quite
>>> possibly unrecoverable boot/shutdown time or suspend/resume time (suspend is
>>> really a special category of 'bootup') crasher oops into a more informative stack
>>> dump.
>>>
>>> These ro related faults tend to trigger when init/deinit is running, and oopsing
>>> in those sequences is typically a lot less survivable than say oopsing in a high
>>> level system call while not holding locks.
>>>
>>
>> I think what should do is have a debug option which can be set to "rw",
>> "log" or "oops"; the latter should probably be the default.
>
> Can someone write that patch, and then I will include it in the
> series? I haven't touched fault handler code, and it would be faster
> if someone more familiar with that area did it. :)

I think I can do it in a week or two if no one beats me to it.

--Andy
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Thread

[PATCH 0/2] introduce post-init read-only memory Kees Cook <keescook@chromium.org> - 2015-11-24 22:40 +0100
  [PATCH 1/2] x86: introduce post-init read-only memory Kees Cook <keescook@chromium.org> - 2015-11-24 22:40 +0100
    Re: [PATCH 1/2] x86: introduce post-init read-only memory Andy Lutomirski <luto@amacapital.net> - 2015-11-25 01:40 +0100
      Re: [PATCH 1/2] x86: introduce post-init read-only memory Kees Cook <keescook@chromium.org> - 2015-11-25 01:50 +0100
        Re: [kernel-hardening] Re: [PATCH 1/2] x86: introduce post-init  read-only memory Michael Ellerman <mpe@ellerman.id.au> - 2015-11-25 02:00 +0100
          Re: [kernel-hardening] Re: [PATCH 1/2] x86: introduce post-init  read-only memory Kees Cook <keescook@chromium.org> - 2015-11-25 16:10 +0100
            Re: [kernel-hardening] Re: [PATCH 1/2] x86: introduce post-init  read-only memory Michael Ellerman <mpe@ellerman.id.au> - 2015-11-26 00:10 +0100
              Re: [kernel-hardening] Re: [PATCH 1/2] x86: introduce post-init  read-only memory Kees Cook <keescook@chromium.org> - 2015-11-26 00:40 +0100
  [PATCH 2/2] x86, vdso: mark vDSO read-only after init Kees Cook <keescook@chromium.org> - 2015-11-24 22:50 +0100
  Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Mathias Krause <minipli@googlemail.com> - 2015-11-25 10:20 +0100
    Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory Clemens Ladisch <clemens@ladisch.de> - 2015-11-25 11:10 +0100
      Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory "PaX Team" <pageexec@freemail.hu> - 2015-11-25 12:20 +0100
    Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory "PaX Team" <pageexec@freemail.hu> - 2015-11-25 12:10 +0100
      Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory Ingo Molnar <mingo@kernel.org> - 2015-11-26 10:00 +0100
        Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory "PaX Team" <pageexec@freemail.hu> - 2015-11-26 11:00 +0100
          Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory Ingo Molnar <mingo@kernel.org> - 2015-11-26 11:50 +0100
            Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory "PaX Team" <pageexec@freemail.hu> - 2015-11-26 13:20 +0100
              Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory Ingo Molnar <mingo@kernel.org> - 2015-11-27 09:10 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory "PaX Team" <pageexec@freemail.hu> - 2015-11-27 16:40 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Andy Lutomirski <luto@amacapital.net> - 2015-11-27 17:40 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory Ingo Molnar <mingo@kernel.org> - 2015-11-29 09:10 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory "PaX Team" <pageexec@freemail.hu> - 2015-11-29 12:20 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory Ingo Molnar <mingo@kernel.org> - 2015-11-29 16:40 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Mathias Krause <minipli@googlemail.com> - 2015-11-29 19:10 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory Ingo Molnar <mingo@kernel.org> - 2015-11-30 09:10 +0100
        Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Andy Lutomirski <luto@amacapital.net> - 2015-11-26 17:20 +0100
          Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory Ingo Molnar <mingo@kernel.org> - 2015-11-27 09:10 +0100
            Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Linus Torvalds <torvalds@linux-foundation.org> - 2015-11-27 19:10 +0100
            Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Linus Torvalds <torvalds@linux-foundation.org> - 2015-11-27 19:10 +0100
              Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Kees Cook <keescook@chromium.org> - 2015-11-27 21:10 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Andy Lutomirski <luto@amacapital.net> - 2015-11-27 21:10 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory Ingo Molnar <mingo@kernel.org> - 2015-11-29 09:10 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory "H. Peter Anvin" <hpa@zytor.com> - 2015-11-30 22:20 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Andy Lutomirski <luto@amacapital.net> - 2015-11-30 22:40 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Kees Cook <keescook@chromium.org> - 2015-11-30 22:40 +0100
                Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory "H. Peter Anvin" <hpa@zytor.com> - 2015-11-30 22:50 +0100
    Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Kees Cook <keescook@chromium.org> - 2015-11-25 18:30 +0100
    Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory "H. Peter Anvin" <hpa@zytor.com> - 2015-11-25 18:40 +0100
      Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory Kees Cook <keescook@chromium.org> - 2015-11-25 20:00 +0100
        Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only  memory "H. Peter Anvin" <hpa@zytor.com> - 2015-11-25 20:10 +0100

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