From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Laura Abbott <labbott@fedoraproject.org>
Cc: Kees Cook <keescook@chromium.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] arm: Use kernel mm when updating section permissions
Date: Thu, 5 Nov 2015 09:46:15 +0000 [thread overview]
Message-ID: <20151105094615.GP8644@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1446685239-28522-1-git-send-email-labbott@fedoraproject.org>
On Wed, Nov 04, 2015 at 05:00:39PM -0800, Laura Abbott wrote:
> Currently, read only permissions are not being applied even
> when CONFIG_DEBUG_RODATA is set. This is because section_update
> uses current->mm for adjusting the page tables. current->mm
> need not be equivalent to the kernel version. Use pgd_offset_k
> to get the proper page directory for updating.
What are you trying to achieve here? You can't use these functions
at run time (after the first thread has been spawned) to change
permissions, because there will be multiple copies of the kernel
section mappings, and those copies will not get updated.
In any case, this change will probably break kexec and ftrace, as
the running thread will no longer see the updated page tables.
--
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
WARNING: multiple messages have this Message-ID (diff)
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Laura Abbott <labbott@fedoraproject.org>
Cc: Kees Cook <keescook@chromium.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] arm: Use kernel mm when updating section permissions
Date: Thu, 5 Nov 2015 09:46:15 +0000 [thread overview]
Message-ID: <20151105094615.GP8644@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1446685239-28522-1-git-send-email-labbott@fedoraproject.org>
On Wed, Nov 04, 2015 at 05:00:39PM -0800, Laura Abbott wrote:
> Currently, read only permissions are not being applied even
> when CONFIG_DEBUG_RODATA is set. This is because section_update
> uses current->mm for adjusting the page tables. current->mm
> need not be equivalent to the kernel version. Use pgd_offset_k
> to get the proper page directory for updating.
What are you trying to achieve here? You can't use these functions
at run time (after the first thread has been spawned) to change
permissions, because there will be multiple copies of the kernel
section mappings, and those copies will not get updated.
In any case, this change will probably break kexec and ftrace, as
the running thread will no longer see the updated page tables.
--
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm: Use kernel mm when updating section permissions
Date: Thu, 5 Nov 2015 09:46:15 +0000 [thread overview]
Message-ID: <20151105094615.GP8644@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1446685239-28522-1-git-send-email-labbott@fedoraproject.org>
On Wed, Nov 04, 2015 at 05:00:39PM -0800, Laura Abbott wrote:
> Currently, read only permissions are not being applied even
> when CONFIG_DEBUG_RODATA is set. This is because section_update
> uses current->mm for adjusting the page tables. current->mm
> need not be equivalent to the kernel version. Use pgd_offset_k
> to get the proper page directory for updating.
What are you trying to achieve here? You can't use these functions
at run time (after the first thread has been spawned) to change
permissions, because there will be multiple copies of the kernel
section mappings, and those copies will not get updated.
In any case, this change will probably break kexec and ftrace, as
the running thread will no longer see the updated page tables.
--
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2015-11-05 9:46 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-05 1:00 [PATCH] arm: Use kernel mm when updating section permissions Laura Abbott
2015-11-05 1:00 ` Laura Abbott
2015-11-05 1:00 ` Laura Abbott
2015-11-05 1:06 ` Kees Cook
2015-11-05 1:06 ` Kees Cook
2015-11-05 1:06 ` Kees Cook
2015-11-05 1:13 ` Kees Cook
2015-11-05 1:13 ` Kees Cook
2015-11-05 1:13 ` Kees Cook
2015-11-05 9:46 ` Russell King - ARM Linux [this message]
2015-11-05 9:46 ` Russell King - ARM Linux
2015-11-05 9:46 ` Russell King - ARM Linux
2015-11-05 16:20 ` Laura Abbott
2015-11-05 16:20 ` Laura Abbott
2015-11-05 16:20 ` Laura Abbott
2015-11-05 16:27 ` Russell King - ARM Linux
2015-11-05 16:27 ` Russell King - ARM Linux
2015-11-05 16:27 ` Russell King - ARM Linux
2015-11-06 1:05 ` Laura Abbott
2015-11-06 1:05 ` Laura Abbott
2015-11-06 1:05 ` Laura Abbott
2015-11-06 1:15 ` Kees Cook
2015-11-06 1:15 ` Kees Cook
2015-11-06 1:15 ` Kees Cook
2015-11-06 18:44 ` Laura Abbott
2015-11-06 18:44 ` Laura Abbott
2015-11-06 18:44 ` Laura Abbott
2015-11-06 19:08 ` Kees Cook
2015-11-06 19:08 ` Kees Cook
2015-11-06 19:08 ` Kees Cook
2015-11-06 19:12 ` Kees Cook
2015-11-06 19:12 ` Kees Cook
2015-11-06 19:12 ` Kees Cook
2015-11-06 20:11 ` Kevin Hilman
2015-11-06 20:11 ` Kevin Hilman
2015-11-06 20:11 ` Kevin Hilman
2015-11-06 20:28 ` Kees Cook
2015-11-06 20:28 ` Kees Cook
2015-11-06 20:28 ` Kees Cook
2015-11-06 21:06 ` Kevin Hilman
2015-11-06 21:06 ` Kevin Hilman
2015-11-06 21:06 ` Kevin Hilman
2015-11-06 21:19 ` Kees Cook
2015-11-06 21:19 ` Kees Cook
2015-11-06 21:19 ` Kees Cook
2015-11-06 22:37 ` Kevin Hilman
2015-11-06 22:37 ` Kevin Hilman
2015-11-06 22:37 ` Kevin Hilman
2015-11-06 23:05 ` Kevin Hilman
2015-11-06 23:05 ` Kevin Hilman
2015-11-06 23:05 ` Kevin Hilman
2015-11-06 23:47 ` Kees Cook
2015-11-06 23:47 ` Kees Cook
2015-11-06 23:47 ` Kees Cook
2015-11-06 20:46 ` Russell King - ARM Linux
2015-11-06 20:46 ` Russell King - ARM Linux
2015-11-06 20:46 ` Russell King - ARM Linux
2015-11-06 23:41 ` Laura Abbott
2015-11-06 23:41 ` Laura Abbott
2015-11-06 23:41 ` Laura Abbott
2015-11-06 23:49 ` Kees Cook
2015-11-06 23:49 ` Kees Cook
2015-11-06 23:49 ` Kees Cook
2015-11-07 0:20 ` Laura Abbott
2015-11-07 0:20 ` Laura Abbott
2015-11-07 0:20 ` Laura Abbott
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