From: David Brown <david.brown@linaro.org>
To: Kees Cook <keescook@chromium.org>
Cc: Russell King <linux@arm.linux.org.uk>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Ingo Molnar <mingo@redhat.com>,
Andy Lutomirski <luto@amacapital.net>,
"H. Peter Anvin" <hpa@zytor.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Mathias Krause <minipli@googlemail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"x86@kernel.org" <x86@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
PaX Team <pageexec@freemail.hu>, Emese Revfy <re.emese@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH] ARM: vdso: Mark vDSO code as read-only
Date: Wed, 17 Feb 2016 16:43:06 -0700 [thread overview]
Message-ID: <20160217234306.GA59532@davidb.org> (raw)
In-Reply-To: <CAGXu5jK22LfvLdMfWz_vbQsJ3bbjSdJrYAp=5yWzD4yRNTTGFQ@mail.gmail.com>
On Wed, Feb 17, 2016 at 03:00:52PM -0800, Kees Cook wrote:
>On Tue, Feb 16, 2016 at 9:20 PM, David Brown <david.brown@linaro.org> wrote:
>> On Tue, Feb 16, 2016 at 01:52:33PM -0800, Kees Cook wrote:
>>>
>>> On Tue, Feb 16, 2016 at 1:36 PM, David Brown <david.brown@linaro.org>
>>> wrote:
>>>>
>>>> Although the arm vDSO is cleanly separated by code/data with the code
>>>> being read-only in userspace mappings, the code page is still writable
>>>> from the kernel. There have been exploits (such as
>>>> http://itszn.com/blog/?p=21) that take advantage of this on x86 to go
>>>> from a bad kernel write to full root.
>>>>
>>>> Prevent this specific exploit on arm by putting the vDSO code page in
>>>> post-init read-only memory as well.
>>>
>>>
>>> Is the vdso dynamically built at init time like on x86, or can this
>>> just use .rodata directly?
>>
>>
>> On ARM, it is patched during init. Arm64's is just plain read-only.
>
>Okay, great. I've added this to my postinit-readonly series (which I
>just refreshed and sent out again...)
However, this distinction between .rodata and .data..ro_after_init is
kind of fuzzy, anyway, since they both get made actually read-only at
the same time (post init). The patch actually does work fine with the
vDSO page in .rodata, since the patching happens during init.
Is there a possible future consideration to perhaps make .rodata read
only much earlier?
David
WARNING: multiple messages have this Message-ID (diff)
From: david.brown@linaro.org (David Brown)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: vdso: Mark vDSO code as read-only
Date: Wed, 17 Feb 2016 16:43:06 -0700 [thread overview]
Message-ID: <20160217234306.GA59532@davidb.org> (raw)
In-Reply-To: <CAGXu5jK22LfvLdMfWz_vbQsJ3bbjSdJrYAp=5yWzD4yRNTTGFQ@mail.gmail.com>
On Wed, Feb 17, 2016 at 03:00:52PM -0800, Kees Cook wrote:
>On Tue, Feb 16, 2016 at 9:20 PM, David Brown <david.brown@linaro.org> wrote:
>> On Tue, Feb 16, 2016 at 01:52:33PM -0800, Kees Cook wrote:
>>>
>>> On Tue, Feb 16, 2016 at 1:36 PM, David Brown <david.brown@linaro.org>
>>> wrote:
>>>>
>>>> Although the arm vDSO is cleanly separated by code/data with the code
>>>> being read-only in userspace mappings, the code page is still writable
>>>> from the kernel. There have been exploits (such as
>>>> http://itszn.com/blog/?p=21) that take advantage of this on x86 to go
>>>> from a bad kernel write to full root.
>>>>
>>>> Prevent this specific exploit on arm by putting the vDSO code page in
>>>> post-init read-only memory as well.
>>>
>>>
>>> Is the vdso dynamically built at init time like on x86, or can this
>>> just use .rodata directly?
>>
>>
>> On ARM, it is patched during init. Arm64's is just plain read-only.
>
>Okay, great. I've added this to my postinit-readonly series (which I
>just refreshed and sent out again...)
However, this distinction between .rodata and .data..ro_after_init is
kind of fuzzy, anyway, since they both get made actually read-only at
the same time (post init). The patch actually does work fine with the
vDSO page in .rodata, since the patching happens during init.
Is there a possible future consideration to perhaps make .rodata read
only much earlier?
David
WARNING: multiple messages have this Message-ID (diff)
From: David Brown <david.brown@linaro.org>
To: Kees Cook <keescook@chromium.org>
Cc: Russell King <linux@arm.linux.org.uk>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Ingo Molnar <mingo@redhat.com>,
Andy Lutomirski <luto@amacapital.net>,
"H. Peter Anvin" <hpa@zytor.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Mathias Krause <minipli@googlemail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"x86@kernel.org" <x86@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
PaX Team <pageexec@freemail.hu>, Emese Revfy <re.emese@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>
Subject: [kernel-hardening] Re: [PATCH] ARM: vdso: Mark vDSO code as read-only
Date: Wed, 17 Feb 2016 16:43:06 -0700 [thread overview]
Message-ID: <20160217234306.GA59532@davidb.org> (raw)
In-Reply-To: <CAGXu5jK22LfvLdMfWz_vbQsJ3bbjSdJrYAp=5yWzD4yRNTTGFQ@mail.gmail.com>
On Wed, Feb 17, 2016 at 03:00:52PM -0800, Kees Cook wrote:
>On Tue, Feb 16, 2016 at 9:20 PM, David Brown <david.brown@linaro.org> wrote:
>> On Tue, Feb 16, 2016 at 01:52:33PM -0800, Kees Cook wrote:
>>>
>>> On Tue, Feb 16, 2016 at 1:36 PM, David Brown <david.brown@linaro.org>
>>> wrote:
>>>>
>>>> Although the arm vDSO is cleanly separated by code/data with the code
>>>> being read-only in userspace mappings, the code page is still writable
>>>> from the kernel. There have been exploits (such as
>>>> http://itszn.com/blog/?p=21) that take advantage of this on x86 to go
>>>> from a bad kernel write to full root.
>>>>
>>>> Prevent this specific exploit on arm by putting the vDSO code page in
>>>> post-init read-only memory as well.
>>>
>>>
>>> Is the vdso dynamically built at init time like on x86, or can this
>>> just use .rodata directly?
>>
>>
>> On ARM, it is patched during init. Arm64's is just plain read-only.
>
>Okay, great. I've added this to my postinit-readonly series (which I
>just refreshed and sent out again...)
However, this distinction between .rodata and .data..ro_after_init is
kind of fuzzy, anyway, since they both get made actually read-only at
the same time (post init). The patch actually does work fine with the
vDSO page in .rodata, since the patching happens during init.
Is there a possible future consideration to perhaps make .rodata read
only much earlier?
David
next prev parent reply other threads:[~2016-02-17 23:43 UTC|newest]
Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-19 18:08 [PATCH v4 0/8] introduce post-init read-only memory Kees Cook
2016-01-19 18:08 ` [kernel-hardening] " Kees Cook
2016-01-19 18:08 ` [PATCH v4 1/8] asm-generic: consolidate mark_rodata_ro() Kees Cook
2016-01-19 18:08 ` [kernel-hardening] " Kees Cook
2016-01-19 18:08 ` [PATCH v4 2/8] lib: add "on" and "off" to strtobool Kees Cook
2016-01-19 18:08 ` [kernel-hardening] " Kees Cook
2016-01-20 2:09 ` Joe Perches
2016-01-20 2:09 ` [kernel-hardening] " Joe Perches
2016-01-22 23:29 ` Kees Cook
2016-01-22 23:29 ` [kernel-hardening] " Kees Cook
2016-01-22 23:29 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 3/8] param: convert some "on"/"off" users " Kees Cook
2016-01-19 18:08 ` [kernel-hardening] " Kees Cook
2016-01-27 21:11 ` David Brown
2016-01-27 21:11 ` David Brown
2016-01-27 21:19 ` [kernel-hardening] " Kees Cook
2016-01-27 21:19 ` Kees Cook
2016-01-28 0:09 ` [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional David Brown
2016-01-28 0:09 ` [kernel-hardening] " David Brown
2016-01-28 0:09 ` David Brown
2016-01-28 0:09 ` David Brown
2016-01-28 0:09 ` David Brown
2016-01-28 0:14 ` Kees Cook
2016-01-28 0:14 ` [kernel-hardening] " Kees Cook
2016-01-28 0:14 ` Kees Cook
2016-01-28 0:14 ` Kees Cook
2016-01-28 0:14 ` Kees Cook
2016-01-28 8:20 ` Ard Biesheuvel
2016-01-28 8:20 ` [kernel-hardening] " Ard Biesheuvel
2016-01-28 8:20 ` Ard Biesheuvel
2016-01-28 8:20 ` Ard Biesheuvel
2016-01-28 8:20 ` Ard Biesheuvel
2016-01-28 11:06 ` Mark Rutland
2016-01-28 11:06 ` [kernel-hardening] " Mark Rutland
2016-01-28 11:06 ` Mark Rutland
2016-01-28 11:06 ` Mark Rutland
2016-01-28 11:06 ` Mark Rutland
2016-01-28 14:06 ` Kees Cook
2016-01-28 14:06 ` [kernel-hardening] " Kees Cook
2016-01-28 14:06 ` Kees Cook
2016-01-28 14:06 ` Kees Cook
2016-01-28 14:06 ` Kees Cook
2016-01-28 14:59 ` Mark Rutland
2016-01-28 14:59 ` [kernel-hardening] " Mark Rutland
2016-01-28 14:59 ` Mark Rutland
2016-01-28 14:59 ` Mark Rutland
2016-01-28 14:59 ` Mark Rutland
2016-01-28 15:17 ` Kees Cook
2016-01-28 15:17 ` [kernel-hardening] " Kees Cook
2016-01-28 15:17 ` Kees Cook
2016-01-28 15:17 ` Kees Cook
2016-01-28 15:17 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 4/8] init: create cmdline param to disable readonly Kees Cook
2016-01-19 18:08 ` [kernel-hardening] " Kees Cook
2016-01-19 18:08 ` [PATCH v4 5/8] x86: make CONFIG_DEBUG_RODATA non-optional Kees Cook
2016-01-19 18:08 ` [kernel-hardening] " Kees Cook
2016-01-19 18:08 ` [PATCH v4 6/8] introduce post-init read-only memory Kees Cook
2016-01-19 18:08 ` [kernel-hardening] " Kees Cook
2016-01-19 18:08 ` [PATCH v4 7/8] lkdtm: verify that __ro_after_init works correctly Kees Cook
2016-01-19 18:08 ` [kernel-hardening] " Kees Cook
2016-01-19 18:08 ` [PATCH v4 8/8] x86, vdso: mark vDSO read-only after init Kees Cook
2016-01-19 18:08 ` [kernel-hardening] " Kees Cook
2016-01-19 19:09 ` Andy Lutomirski
2016-01-19 19:09 ` [kernel-hardening] " Andy Lutomirski
2016-01-19 19:09 ` Andy Lutomirski
2016-01-20 2:51 ` H. Peter Anvin
2016-01-20 2:51 ` [kernel-hardening] " H. Peter Anvin
2016-01-20 2:56 ` Andy Lutomirski
2016-01-20 2:56 ` [kernel-hardening] " Andy Lutomirski
2016-01-20 2:56 ` Andy Lutomirski
2016-01-22 17:19 ` [kernel-hardening] [PATCH v4 0/8] introduce post-init read-only memory David Brown
2016-01-22 17:19 ` David Brown
2016-01-22 19:16 ` [kernel-hardening] " Laura Abbott
2016-01-22 19:57 ` Kees Cook
2016-01-22 19:57 ` Kees Cook
2016-01-23 9:49 ` Geert Uytterhoeven
2016-01-23 9:49 ` Geert Uytterhoeven
2016-02-16 21:36 ` [PATCH] ARM: vdso: Mark vDSO code as read-only David Brown
2016-02-16 21:36 ` [kernel-hardening] " David Brown
2016-02-16 21:36 ` David Brown
2016-02-16 21:52 ` Kees Cook
2016-02-16 21:52 ` [kernel-hardening] " Kees Cook
2016-02-16 21:52 ` Kees Cook
2016-02-16 21:52 ` Kees Cook
2016-02-17 5:20 ` David Brown
2016-02-17 5:20 ` [kernel-hardening] " David Brown
2016-02-17 5:20 ` David Brown
2016-02-17 5:20 ` David Brown
2016-02-17 23:00 ` Kees Cook
2016-02-17 23:00 ` [kernel-hardening] " Kees Cook
2016-02-17 23:00 ` Kees Cook
2016-02-17 23:00 ` Kees Cook
2016-02-17 23:43 ` David Brown [this message]
2016-02-17 23:43 ` [kernel-hardening] " David Brown
2016-02-17 23:43 ` David Brown
2016-02-17 23:43 ` David Brown
2016-02-17 23:48 ` Kees Cook
2016-02-17 23:48 ` [kernel-hardening] " Kees Cook
2016-02-17 23:48 ` Kees Cook
2016-02-17 23:48 ` Kees Cook
2016-02-18 10:46 ` PaX Team
2016-02-18 10:46 ` [kernel-hardening] " PaX Team
2016-02-18 10:46 ` PaX Team
2016-02-18 10:46 ` PaX Team
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