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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Jordan Niethe <jniethe5@gmail.com>,
	Michael Ellerman <mpe@ellerman.id.au>
Cc: ajd@linux.ibm.com, Kees Cook <keescook@chromium.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	cmr@codefail.de, naveen.n.rao@linux.ibm.com,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Daniel Axtens <dja@axtens.net>
Subject: Re: [PATCH v10 06/10] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime
Date: Wed, 21 Apr 2021 07:16:16 +0200
Message-ID: <825f6dc7-637a-dab3-f659-db5b62a9f73d@csgroup.eu> (raw)
In-Reply-To: <CACzsE9pgZRaoHT0Ca=NB3srEMJMvLuiFkYA98xFDiUPyfmoV5Q@mail.gmail.com>



Le 21/04/2021 à 04:23, Jordan Niethe a écrit :
> On Wed, Mar 31, 2021 at 10:24 PM Michael Ellerman <mpe@ellerman.id.au> wrote:
>>
>> Jordan Niethe <jniethe5@gmail.com> writes:
>>> From: Russell Currey <ruscur@russell.cc>
>>>
>>> Optionally run W+X checks when dumping pagetable information to
>>> debugfs' kernel_page_tables.
>>>
>>> To use:
>>>      $ echo 1 > /sys/kernel/debug/check_wx_pages
>>>      $ cat /sys/kernel/debug/kernel_page_tables
>>>
>>> and check the kernel log.  Useful for testing strict module RWX.
>>>
>>> To disable W+X checks:
>>>        $ echo 0 > /sys/kernel/debug/check_wx_pages
>>>
>>> Update the Kconfig entry to reflect this.
>>>
>>> Also fix a typo.
>>>
>>> Reviewed-by: Kees Cook <keescook@chromium.org>
>>> Signed-off-by: Russell Currey <ruscur@russell.cc>
>>> [jpn: Change check_wx_pages to act as mode bit affecting
>>>        kernel_page_tables instead of triggering action on its own]
>>> Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
>>> ---
>>> v10: check_wx_pages now affects kernel_page_tables rather then triggers
>>>       its own action.
>>
>> Hmm. I liked the old version better :)
>>
>> I think you changed it based on Christophe's comment:
>>
>>    Why not just perform the test everytime someone dumps kernel_page_tables ?
>>
>>
>> But I think he meant *always* do the check when someone dumps
>> kernel_page_tables, not have another file to enable checking and then
>> require someone to dump kernel_page_tables to do the actual check.
> Yes, I guess I misinterpreted that.
>>
>> Still I like the previous version where you can do the checks
>> separately, without having to dump the page tables, because dumping can
>> sometimes take quite a while.
>>
>> What would be even better is if ptdump_check_wx() returned an error when
>> wx pages were found, and that was plumbed out to the debugs file. That
>> way you can script around it.
> Ok I'll go back to how it was and add in returning an error.

I have a series to convert PPC_PTDUMP into GENERIC_PTDUMP, see 
https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=239795

>>
>> cheers

  reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-30  4:51 [PATCH v10 00/10] powerpc: Further Strict RWX support Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 01/10] powerpc/mm: Implement set_memory() routines Jordan Niethe
2021-03-30  5:16   ` Christophe Leroy
2021-04-21  2:51     ` Jordan Niethe
2021-03-31 11:16   ` Michael Ellerman
2021-03-31 12:03     ` Christophe Leroy
2021-04-21  5:03     ` Jordan Niethe
2021-04-01  4:37   ` Aneesh Kumar K.V
2021-04-21  5:19     ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 02/10] powerpc/lib/code-patching: Set up Strict RWX patching earlier Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 03/10] powerpc: Always define MODULES_{VADDR,END} Jordan Niethe
2021-03-30  5:00   ` Christophe Leroy
2021-04-01 13:36   ` Christophe Leroy
2021-04-21  2:46     ` Jordan Niethe
2021-04-21  5:14       ` Christophe Leroy
2021-04-21  5:22         ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 04/10] powerpc/kprobes: Mark newly allocated probes as ROX Jordan Niethe
2021-03-30  5:05   ` Christophe Leroy
2021-04-21  2:39     ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 05/10] powerpc/bpf: Write protect JIT code Jordan Niethe
2021-03-31 10:37   ` Michael Ellerman
2021-03-31 10:39     ` Christophe Leroy
2021-04-21  2:35     ` Jordan Niethe
2021-04-21  6:51       ` Michael Ellerman
2021-03-30  4:51 ` [PATCH v10 06/10] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime Jordan Niethe
2021-03-31 11:24   ` Michael Ellerman
2021-04-21  2:23     ` Jordan Niethe
2021-04-21  5:16       ` Christophe Leroy [this message]
2021-03-30  4:51 ` [PATCH v10 07/10] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 08/10] powerpc/configs: Enable STRICT_MODULE_RWX in skiroot_defconfig Jordan Niethe
2021-03-30  5:27   ` Christophe Leroy
2021-04-21  2:37     ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 09/10] powerpc/mm: implement set_memory_attr() Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 10/10] powerpc/32: use set_memory_attr() Jordan Niethe

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