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Date:   Tue, 6 Dec 2022 17:35:29 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Jeff Xu <jeffxu@google.com>
Cc:     jeffxu@chromium.org, skhan@linuxfoundation.org,
        keescook@chromium.org, akpm@linux-foundation.org,
        dmitry.torokhov@gmail.com, dverkamp@chromium.org, hughd@google.com,
        jorgelo@chromium.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-mm@kvack.org,
        jannh@google.com, linux-hardening@vger.kernel.org,
        kernel test robot <lkp@intel.com>
Subject: Re: [PATCH v5 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC
Message-ID: <Y49vUQKRVyquazJ2@kroah.com>
References: <20221206152358.1966099-1-jeffxu@google.com>
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 <CALmYWFvaEg84DYtjQtoQqsvaboX7mRS5dOqz8OJ0EYJTOCp4kg@mail.gmail.com>
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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