On Tue, 2020-05-19 at 18:04 -0700, Andy Lutomirski wrote:
> On Mon, May 18, 2020 at 6:35 PM Andy Lutomirski wrote:
> > [...]
> > > On May 18, 2020, at 5:38 PM, Dave Hansen wrote:
> > > [...]
> > > The sadistic parts of selftests/x86 come from real bugs. Either bugs
> > > where the kernel fell ov
On 22/05/2020 17:49, Peter Zijlstra wrote:
> On Sat, May 16, 2020 at 03:09:22PM +0100, Andrew Cooper wrote:
>
>> Sadly, the same is not true for kernel shadow stacks.
>>
>> SSP is 0 after SYSCALL, SYSENTER and CLRSSBSY, and you've got to be
>> careful to re-establish the shadow stack before a CALL,
On Sat, May 16, 2020 at 03:09:22PM +0100, Andrew Cooper wrote:
> Sadly, the same is not true for kernel shadow stacks.
>
> SSP is 0 after SYSCALL, SYSENTER and CLRSSBSY, and you've got to be
> careful to re-establish the shadow stack before a CALL, interrupt or
> exception tries pushing a word on
On Mon, May 18, 2020 at 6:35 PM Andy Lutomirski wrote:
>
>
>
> > On May 18, 2020, at 5:38 PM, Dave Hansen wrote:
> >
> > On 5/18/20 4:47 PM, Yu-cheng Yu wrote:
> >>> On Fri, 2020-05-15 at 19:53 -0700, Yu-cheng Yu wrote:
> >>> On Fri, 2020-05-15 at 16:56 -0700, Dave Hansen wrote:
> On 5/15/2
> On May 18, 2020, at 5:38 PM, Dave Hansen wrote:
>
> On 5/18/20 4:47 PM, Yu-cheng Yu wrote:
>>> On Fri, 2020-05-15 at 19:53 -0700, Yu-cheng Yu wrote:
>>> On Fri, 2020-05-15 at 16:56 -0700, Dave Hansen wrote:
On 5/15/20 4:29 PM, Yu-cheng Yu wrote:
> [...]
> I have run them with C
On 5/18/20 4:47 PM, Yu-cheng Yu wrote:
> On Fri, 2020-05-15 at 19:53 -0700, Yu-cheng Yu wrote:
>> On Fri, 2020-05-15 at 16:56 -0700, Dave Hansen wrote:
>>> On 5/15/20 4:29 PM, Yu-cheng Yu wrote:
[...]
I have run them with CET enabled. All of them pass, except for the
following:
>>>
On Fri, 2020-05-15 at 19:53 -0700, Yu-cheng Yu wrote:
> On Fri, 2020-05-15 at 16:56 -0700, Dave Hansen wrote:
> > On 5/15/20 4:29 PM, Yu-cheng Yu wrote:
> > > [...]
> > > I have run them with CET enabled. All of them pass, except for the
> > > following:
> > > Sigreturn from 64-bit to 32-bit fail
On 5/18/20 7:01 AM, H.J. Lu wrote:
>> Could some of this information be added to the documentation, please?
>> It would also be nice to have some more details about how apps end up
>> using ARCH_X86_CET_STATUS. Why would they care that CET is on?
> CET software spec is at
>
> https://gitlab.com/x
On Mon, 2020-05-18 at 06:41 -0700, Dave Hansen wrote:
> On 5/15/20 7:53 PM, Yu-cheng Yu wrote:
> > On Fri, 2020-05-15 at 16:56 -0700, Dave Hansen wrote:
> > > What's my recourse as an end user? I want to run my app and turn off
> > > CET for that app. How can I do that?
> >
> > GLIBC_TUNABLES=gl
On Mon, May 18, 2020 at 6:41 AM Dave Hansen wrote:
>
> On 5/15/20 7:53 PM, Yu-cheng Yu wrote:
> > On Fri, 2020-05-15 at 16:56 -0700, Dave Hansen wrote:
> >> What's my recourse as an end user? I want to run my app and turn off
> >> CET for that app. How can I do that?
> >
> > GLIBC_TUNABLES=glibc
On 5/15/20 7:53 PM, Yu-cheng Yu wrote:
> On Fri, 2020-05-15 at 16:56 -0700, Dave Hansen wrote:
>> What's my recourse as an end user? I want to run my app and turn off
>> CET for that app. How can I do that?
>
> GLIBC_TUNABLES=glibc.tune.hwcaps=-SHSTK,-IBT
Like I mentioned to H.J., this is somet
On 5/15/20 7:51 PM, H.J. Lu wrote:
> On Fri, May 15, 2020 at 4:56 PM Dave Hansen wrote:
>> Let's say we have an app doing silly things like retpolines. (Lots of
>> app do lots of silly things). It gets compiled in a distro but never
>> runs on a system with CET. The app gets run for the first t
On 16/05/2020 03:37, H.J. Lu wrote:
> On Fri, May 15, 2020 at 5:13 PM Andrew Cooper
> wrote:
>> Finally seeing as the question was asked but not answered, it is
>> actually quite easy to figure out whether shadow stacks are enabled in
>> the current thread.
>>
>> mov $1, %eax
>> rdssp
On Fri, May 15, 2020 at 4:56 PM Dave Hansen wrote:
>
> On 5/15/20 4:29 PM, Yu-cheng Yu wrote:
> > On Fri, 2020-05-15 at 15:43 -0700, Dave Hansen wrote:
> >> Basically, if there ends up being a bug in an app that violates the
> >> shadow stack rules, the app is broken, period. The only recourse is
On Fri, 2020-05-15 at 16:56 -0700, Dave Hansen wrote:
> On 5/15/20 4:29 PM, Yu-cheng Yu wrote:
> > On Fri, 2020-05-15 at 15:43 -0700, Dave Hansen wrote:
> > > Basically, if there ends up being a bug in an app that violates the
> > > shadow stack rules, the app is broken, period. The only recourse
On Fri, May 15, 2020 at 5:13 PM Andrew Cooper wrote:
>
> On 15/05/2020 23:43, Dave Hansen wrote:
> > On 5/15/20 2:33 PM, Yu-cheng Yu wrote:
> >> On Fri, 2020-05-15 at 11:39 -0700, Dave Hansen wrote:
> >>> On 5/12/20 4:20 PM, Yu-cheng Yu wrote:
> >>> Can a binary compiled with CET run without CET?
On 15/05/2020 23:43, Dave Hansen wrote:
> On 5/15/20 2:33 PM, Yu-cheng Yu wrote:
>> On Fri, 2020-05-15 at 11:39 -0700, Dave Hansen wrote:
>>> On 5/12/20 4:20 PM, Yu-cheng Yu wrote:
>>> Can a binary compiled with CET run without CET?
>> Yes, but a few details:
>>
>> - The shadow stack is transparent
On 5/15/20 4:29 PM, Yu-cheng Yu wrote:
> On Fri, 2020-05-15 at 15:43 -0700, Dave Hansen wrote:
>> Basically, if there ends up being a bug in an app that violates the
>> shadow stack rules, the app is broken, period. The only recourse is to
>> have the kernel disable CET and reboot.
>>
>> Is that r
On Fri, 2020-05-15 at 15:43 -0700, Dave Hansen wrote:
> On 5/15/20 2:33 PM, Yu-cheng Yu wrote:
> > On Fri, 2020-05-15 at 11:39 -0700, Dave Hansen wrote:
> > > On 5/12/20 4:20 PM, Yu-cheng Yu wrote:
> > > Can a binary compiled with CET run without CET?
> >
> > Yes, but a few details:
> >
> > - The
On 5/15/20 2:33 PM, Yu-cheng Yu wrote:
> On Fri, 2020-05-15 at 11:39 -0700, Dave Hansen wrote:
>> On 5/12/20 4:20 PM, Yu-cheng Yu wrote:
>> Can a binary compiled with CET run without CET?
>
> Yes, but a few details:
>
> - The shadow stack is transparent to the application. A CET application does
On Fri, 2020-05-15 at 11:39 -0700, Dave Hansen wrote:
> On 5/12/20 4:20 PM, Yu-cheng Yu wrote:
> > On Wed, 2020-04-29 at 16:02 -0700, Yu-cheng Yu wrote:
> > > On Wed, 2020-04-29 at 15:53 -0700, Dave Hansen wrote:
> > > > On 4/29/20 3:07 PM, Yu-cheng Yu wrote:
> > > > > +Note:
> > > > > + There is
On 5/12/20 4:20 PM, Yu-cheng Yu wrote:
> On Wed, 2020-04-29 at 16:02 -0700, Yu-cheng Yu wrote:
>> On Wed, 2020-04-29 at 15:53 -0700, Dave Hansen wrote:
>>> On 4/29/20 3:07 PM, Yu-cheng Yu wrote:
+Note:
+ There is no CET-enabling arch_prctl function. By design, CET is enabled
+ aut
On Wed, 2020-04-29 at 16:02 -0700, Yu-cheng Yu wrote:
> On Wed, 2020-04-29 at 15:53 -0700, Dave Hansen wrote:
> > On 4/29/20 3:07 PM, Yu-cheng Yu wrote:
> > > +Note:
> > > + There is no CET-enabling arch_prctl function. By design, CET is
> > > enabled
> > > + automatically if the binary and the
On Wed, 2020-04-29 at 15:53 -0700, Dave Hansen wrote:
> On 4/29/20 3:07 PM, Yu-cheng Yu wrote:
> > +Note:
> > + There is no CET-enabling arch_prctl function. By design, CET is enabled
> > + automatically if the binary and the system can support it.
>
> I think Andy and I danced around this last
On 4/29/20 3:07 PM, Yu-cheng Yu wrote:
> +Note:
> + There is no CET-enabling arch_prctl function. By design, CET is enabled
> + automatically if the binary and the system can support it.
I think Andy and I danced around this last time. Let me try to say it
more explicitly.
I want CET kernel e
Explain no_user_shstk/no_user_ibt kernel parameters, and introduce a new
document on Control-flow Enforcement Technology (CET).
Signed-off-by: Yu-cheng Yu
Reviewed-by: Kees Cook
---
v10:
- Change no_cet_shstk and no_cet_ibt to no_user_shstk and no_user_ibt.
- Remove the opcode section, as it is
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