Re: [PATCH v5 5/6] selftests/memfd: add tests for MFD_NOEXEC_SEAL MFD_EXEC

Re: [PATCH v5 5/6] selftests/memfd: add tests for MFD_NOEXEC_SEAL MFD_EXEC

[Greg KH]

On Tue, Dec 06, 2022 at 03:23:57PM +0000, jeffxu@chromium.org wrote:
> From: Jeff Xu <jeffxu@chromium.org>
> 
> Tests to verify MFD_NOEXEC, MFD_EXEC and vm.memfd_noexec sysctl.
> 
> Signed-off-by: Jeff Xu <jeffxu@chromium.org>
> Co-developed-by: Daniel Verkamp <dverkamp@chromium.org>
> Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
> 
> Change-Id: Idccec1141255ca948c849f4efc8ba5e97f78b6eb

Always use checkpatch.pl on your patches so you don't get grumpy
maintainers telling you to run checkpatch.pl on your patches...

thanks,

greg k-h

Re: [PATCH v5 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC

[Greg KH]

On Tue, Dec 06, 2022 at 03:23:55PM +0000, jeffxu@chromium.org wrote:
> --- a/kernel/pid_namespace.c
> +++ b/kernel/pid_namespace.c
> @@ -110,6 +110,11 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
>  	ns->ucounts = ucounts;
>  	ns->pid_allocated = PIDNS_ADDING;
>  
> +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> +	ns->memfd_noexec_scope =
> +		task_active_pid_ns(current)->memfd_noexec_scope;
> +#endif

.c files should never have #if in them.  Can't you put this in a .h file
properly so that this does not get really messy over time?



> +
>  	return ns;
>  
>  out_free_idr:
> @@ -255,6 +260,45 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
>  	return;
>  }
>  
> +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)

Same here.

thanks,

greg k-h

Re: [PATCH v5 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC

[Jeff Xu]

On Tue, Dec 6, 2022 at 8:04 AM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Tue, Dec 06, 2022 at 03:23:55PM +0000, jeffxu@chromium.org wrote:
> > --- a/kernel/pid_namespace.c
> > +++ b/kernel/pid_namespace.c
> > @@ -110,6 +110,11 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
> >       ns->ucounts = ucounts;
> >       ns->pid_allocated = PIDNS_ADDING;
> >
> > +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> > +     ns->memfd_noexec_scope =
> > +             task_active_pid_ns(current)->memfd_noexec_scope;
> > +#endif
>
> .c files should never have #if in them.  Can't you put this in a .h file
> properly so that this does not get really messy over time?
>
>
Thanks for reviewing.
It seems to me that checking for CONFIG_XXX is  common in c code in
kernel/ path.
Do you have a sample code pattern (link/function) that I can follow?

Thanks
Jeff

>
> > +
> >       return ns;
> >
> >  out_free_idr:
> > @@ -255,6 +260,45 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
> >       return;
> >  }
> >
> > +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
>
> Same here.
>
> thanks,
>
> greg k-h

Re: [PATCH v5 5/6] selftests/memfd: add tests for MFD_NOEXEC_SEAL MFD_EXEC

[Jeff Xu]

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On Tue, Dec 6, 2022 at 8:02 AM Greg KH <gregkh@linuxfoundation.org> wrote:

> On Tue, Dec 06, 2022 at 03:23:57PM +0000, jeffxu@chromium.org wrote:
> > From: Jeff Xu <jeffxu@chromium.org>
> >
> > Tests to verify MFD_NOEXEC, MFD_EXEC and vm.memfd_noexec sysctl.
> >
> > Signed-off-by: Jeff Xu <jeffxu@chromium.org>
> > Co-developed-by: Daniel Verkamp <dverkamp@chromium.org>
> > Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
> >
> > Change-Id: Idccec1141255ca948c849f4efc8ba5e97f78b6eb
>
> Always use checkpatch.pl on your patches so you don't get grumpy
> maintainers telling you to run checkpatch.pl on your patches...
>
>
Will do, thanks for pointing it out.
Jeff


> thanks,
>
> greg k-h
>

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Re: [PATCH v5 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC

[Greg KH]

On Tue, Dec 06, 2022 at 08:26:30AM -0800, Jeff Xu wrote:
> On Tue, Dec 6, 2022 at 8:04 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Tue, Dec 06, 2022 at 03:23:55PM +0000, jeffxu@chromium.org wrote:
> > > --- a/kernel/pid_namespace.c
> > > +++ b/kernel/pid_namespace.c
> > > @@ -110,6 +110,11 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
> > >       ns->ucounts = ucounts;
> > >       ns->pid_allocated = PIDNS_ADDING;
> > >
> > > +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> > > +     ns->memfd_noexec_scope =
> > > +             task_active_pid_ns(current)->memfd_noexec_scope;
> > > +#endif
> >
> > .c files should never have #if in them.  Can't you put this in a .h file
> > properly so that this does not get really messy over time?
> >
> >
> Thanks for reviewing.
> It seems to me that checking for CONFIG_XXX is  common in c code in
> kernel/ path.

Maybe, but please don't make it any worse if at all possible.  It's
tough to maintain code like that.

> Do you have a sample code pattern (link/function) that I can follow?

Any of the zillions of #if statements in .h files :)

thanks,

greg k-h

Re: [PATCH v5 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC

[Jeff Xu]

On Tue, Dec 6, 2022 at 8:35 AM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Tue, Dec 06, 2022 at 08:26:30AM -0800, Jeff Xu wrote:
> > On Tue, Dec 6, 2022 at 8:04 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Tue, Dec 06, 2022 at 03:23:55PM +0000, jeffxu@chromium.org wrote:
> > > > --- a/kernel/pid_namespace.c
> > > > +++ b/kernel/pid_namespace.c
> > > > @@ -110,6 +110,11 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
> > > >       ns->ucounts = ucounts;
> > > >       ns->pid_allocated = PIDNS_ADDING;
> > > >
> > > > +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> > > > +     ns->memfd_noexec_scope =
> > > > +             task_active_pid_ns(current)->memfd_noexec_scope;
> > > > +#endif
> > >
> > > .c files should never have #if in them.  Can't you put this in a .h file
> > > properly so that this does not get really messy over time?
> > >
> > >
> > Thanks for reviewing.
> > It seems to me that checking for CONFIG_XXX is  common in c code in
> > kernel/ path.
>
> Maybe, but please don't make it any worse if at all possible.  It's
> tough to maintain code like that.
>
> > Do you have a sample code pattern (link/function) that I can follow?
>
> Any of the zillions of #if statements in .h files :)
>
Thanks.
I will take the approach of having real/stub implementation in the h
file, and the c file  using it without a compile flag.
Please kindly let me know if this is not right.

Thanks
Jeff

> thanks,
>
> greg k-h

Re: [PATCH v5 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC

[Kees Cook]

On Tue, Dec 06, 2022 at 09:48:55AM -0800, Jeff Xu wrote:
> On Tue, Dec 6, 2022 at 8:35 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Tue, Dec 06, 2022 at 08:26:30AM -0800, Jeff Xu wrote:
> > > On Tue, Dec 6, 2022 at 8:04 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > On Tue, Dec 06, 2022 at 03:23:55PM +0000, jeffxu@chromium.org wrote:
> > > > > --- a/kernel/pid_namespace.c
> > > > > +++ b/kernel/pid_namespace.c
> > > > > @@ -110,6 +110,11 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
> > > > >       ns->ucounts = ucounts;
> > > > >       ns->pid_allocated = PIDNS_ADDING;
> > > > >
> > > > > +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> > > > > +     ns->memfd_noexec_scope =
> > > > > +             task_active_pid_ns(current)->memfd_noexec_scope;
> > > > > +#endif
> > > >
> > > > .c files should never have #if in them.  Can't you put this in a .h file
> > > > properly so that this does not get really messy over time?
> > > >
> > > >
> > > Thanks for reviewing.
> > > It seems to me that checking for CONFIG_XXX is  common in c code in
> > > kernel/ path.
> >
> > Maybe, but please don't make it any worse if at all possible.  It's
> > tough to maintain code like that.
> >
> > > Do you have a sample code pattern (link/function) that I can follow?
> >
> > Any of the zillions of #if statements in .h files :)
> >
> Thanks.
> I will take the approach of having real/stub implementation in the h
> file, and the c file  using it without a compile flag.
> Please kindly let me know if this is not right.

Right; for example:

in .h:

#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
static inline void ns_copy_memfd_scope(... dst, ... src) {
	dst->memfd_noexec_scope = src->memfd_noexec_scope;
}
#else
static inline void ns_set_memfd_scope(... ns, ... scope) { }
#endif


in .c:

	ns_copy_memfd_scope(ns, task_active_pid_ns(current));


-- 
Kees Cook