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Groups > linux.kernel > #1617439
| From | Kees Cook <keescook@chromium.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() |
| Date | 2017-04-06 02:20 +0200 |
| Message-ID | <tt3jz-18Z-7@gated-at.bofh.it> (permalink) |
| References | <tqqml-2iB-7@gated-at.bofh.it> <tqqmm-2iB-39@gated-at.bofh.it> <tqupX-59N-9@gated-at.bofh.it> <tqxnP-7bX-5@gated-at.bofh.it> <tt30d-NG-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, Apr 5, 2017 at 4:57 PM, Andy Lutomirski <luto@kernel.org> wrote:
> On Wed, Mar 29, 2017 at 6:41 PM, Kees Cook <keescook@chromium.org> wrote:
>> On Wed, Mar 29, 2017 at 3:38 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>>> On Wed, Mar 29, 2017 at 11:15 AM, Kees Cook <keescook@chromium.org> wrote:
>>>> Based on PaX's x86 pax_{open,close}_kernel() implementation, this
>>>> allows HAVE_ARCH_RARE_WRITE to work on x86.
>>>>
>>>
>>>> +
>>>> +static __always_inline unsigned long __arch_rare_write_begin(void)
>>>> +{
>>>> + unsigned long cr0;
>>>> +
>>>> + preempt_disable();
>>>
>>> This looks wrong. DEBUG_LOCKS_WARN_ON(!irqs_disabled()) would work,
>>> as would local_irq_disable(). There's no way that just disabling
>>> preemption is enough.
>>>
>>> (Also, how does this interact with perf nmis?)
>>
>> Do you mean preempt_disable() isn't strong enough here? I'm open to
>> suggestions. The goal would be to make sure nothing between _begin and
>> _end would get executed without interruption...
>>
>
> Sorry for the very slow response.
>
> preempt_disable() isn't strong enough to prevent interrupts, and an
> interrupt here would run with WP off, causing unknown havoc. I tend
> to think that the caller should be responsible for turning off
> interrupts.
So, something like:
Top-level functions:
static __always_inline rare_write_begin(void)
{
preempt_disable();
local_irq_disable();
barrier();
__arch_rare_write_begin();
barrier();
}
static __always_inline rare_write_end(void)
{
barrier();
__arch_rare_write_end();
barrier();
local_irq_enable();
preempt_enable_no_resched();
}
x86-specific helpers:
static __always_inline unsigned long __arch_rare_write_begin(void)
{
unsigned long cr0;
cr0 = read_cr0() ^ X86_CR0_WP;
BUG_ON(cr0 & X86_CR0_WP);
write_cr0(cr0);
return cr0 ^ X86_CR0_WP;
}
static __always_inline unsigned long __arch_rare_write_end(void)
{
unsigned long cr0;
cr0 = read_cr0() ^ X86_CR0_WP;
BUG_ON(!(cr0 & X86_CR0_WP));
write_cr0(cr0);
return cr0 ^ X86_CR0_WP;
}
I can give it a spin...
-Kees
--
Kees Cook
Pixel Security
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[RFC v2] Introduce rare_write() infrastructure Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
[RFC v2][PATCH 10/11] gcc-plugins: Add constify plugin Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
[RFC v2][PATCH 03/11] net: switch sock_diag handlers to rare_write() Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
[RFC v2][PATCH 07/11] ARM: mm: set DOMAIN_WR_RARE for rodata Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
[RFC v2][PATCH 01/11] Introduce rare_write() infrastructure Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
Re: [RFC v2][PATCH 01/11] Introduce rare_write() infrastructure Kees Cook <keescook@chromium.org> - 2017-03-29 20:30 +0200
Re: [RFC v2][PATCH 01/11] Introduce rare_write() infrastructure Ho-Eun Ryu <hoeun.ryu@gmail.com> - 2017-03-30 09:50 +0200
Re: [RFC v2][PATCH 01/11] Introduce rare_write() infrastructure Kees Cook <keescook@chromium.org> - 2017-03-30 19:10 +0200
Re: [RFC v2][PATCH 01/11] Introduce rare_write() infrastructure Ho-Eun Ryu <hoeun.ryu@gmail.com> - 2017-04-07 10:20 +0200
Re: [RFC v2][PATCH 01/11] Introduce rare_write() infrastructure Kees Cook <keescook@chromium.org> - 2017-04-07 22:40 +0200
[RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Andy Lutomirski <luto@amacapital.net> - 2017-03-30 00:40 +0200
Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Kees Cook <keescook@chromium.org> - 2017-03-30 03:50 +0200
Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Andy Lutomirski <luto@kernel.org> - 2017-04-06 02:00 +0200
Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Kees Cook <keescook@chromium.org> - 2017-04-06 02:20 +0200
Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Andy Lutomirski <luto@amacapital.net> - 2017-04-06 18:00 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Mathias Krause <minipli@googlemail.com> - 2017-04-07 10:40 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Thomas Gleixner <tglx@linutronix.de> - 2017-04-07 11:50 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Mathias Krause <minipli@googlemail.com> - 2017-04-07 13:00 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Thomas Gleixner <tglx@linutronix.de> - 2017-04-07 15:20 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Mathias Krause <minipli@googlemail.com> - 2017-04-07 15:40 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Andy Lutomirski <luto@kernel.org> - 2017-04-07 18:20 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Mark Rutland <mark.rutland@arm.com> - 2017-04-07 18:30 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() "PaX Team" <pageexec@freemail.hu> - 2017-04-07 22:10 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Andy Lutomirski <luto@kernel.org> - 2017-04-08 07:00 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() "PaX Team" <pageexec@freemail.hu> - 2017-04-09 14:50 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Andy Lutomirski <luto@kernel.org> - 2017-04-10 02:20 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() "PaX Team" <pageexec@freemail.hu> - 2017-04-10 12:50 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Thomas Gleixner <tglx@linutronix.de> - 2017-04-07 22:50 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Kees Cook <keescook@chromium.org> - 2017-04-07 23:30 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Daniel Micay <danielmicay@gmail.com> - 2017-04-08 06:20 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Daniel Micay <danielmicay@gmail.com> - 2017-04-08 06:20 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Daniel Micay <danielmicay@gmail.com> - 2017-04-08 06:30 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Andy Lutomirski <luto@kernel.org> - 2017-04-08 07:10 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Daniel Micay <danielmicay@gmail.com> - 2017-04-08 09:40 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Andy Lutomirski <luto@kernel.org> - 2017-04-08 17:30 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Ingo Molnar <mingo@kernel.org> - 2017-04-09 13:00 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Mark Rutland <mark.rutland@arm.com> - 2017-04-10 12:30 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() "PaX Team" <pageexec@freemail.hu> - 2017-04-09 22:30 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Andy Lutomirski <luto@kernel.org> - 2017-04-10 02:40 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Thomas Gleixner <tglx@linutronix.de> - 2017-04-07 21:30 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Peter Zijlstra <peterz@infradead.org> - 2017-04-07 16:50 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Mark Rutland <mark.rutland@arm.com> - 2017-04-10 12:40 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() "PaX Team" <pageexec@freemail.hu> - 2017-04-07 22:40 +0200
Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Thomas Gleixner <tglx@linutronix.de> - 2017-04-10 10:30 +0200
Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Peter Zijlstra <peterz@infradead.org> - 2017-04-07 11:40 +0200
[RFC v2][PATCH 09/11] list: add rare_write() list helpers Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
[RFC v2][PATCH 05/11] ARM: mm: dump: Add domain to output Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
[RFC v2][PATCH 11/11] cgroups: force all struct cftype const Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
[RFC v2][PATCH 08/11] ARM: Implement __arch_rare_write_begin/end() Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
Re: [RFC v2][PATCH 08/11] ARM: Implement __arch_rare_write_begin/end() Peter Zijlstra <peterz@infradead.org> - 2017-04-07 11:40 +0200
[RFC v2][PATCH 02/11] lkdtm: add test for rare_write() infrastructure Kees Cook <keescook@chromium.org> - 2017-03-29 20:20 +0200
Re: [kernel-hardening] [RFC v2][PATCH 02/11] lkdtm: add test for rare_write() infrastructure Ian Campbell <ijc@hellion.org.uk> - 2017-03-30 12:20 +0200
Re: [kernel-hardening] [RFC v2][PATCH 02/11] lkdtm: add test for rare_write() infrastructure Kees Cook <keescook@chromium.org> - 2017-03-30 18:20 +0200
Re: [RFC v2] Introduce rare_write() infrastructure Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-29 21:10 +0200
Re: [RFC v2] Introduce rare_write() infrastructure Kees Cook <keescook@chromium.org> - 2017-03-29 21:20 +0200
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