Re: [PATCH 6/9] fs: Introduce file_to_perms() helper

Kees Cook
2022-10-18T18:25:42Z

On Tue, Oct 18, 2022 at 04:10:37PM +0200, Christian Brauner wrote:
> On Thu, Oct 13, 2022 at 03:36:51PM -0700, Kees Cook wrote:
> > Extract the logic used by LSM file hooks to be able to reconstruct the
> > access mode permissions from an open.
> >
> > Cc: John Johansen <john.johansen@canonical.com>
> > Cc: Paul Moore <paul@paul-moore.com>
> > Cc: James Morris <jmorris@namei.org>
> > Cc: "Serge E. Hallyn" <serge@hallyn.com>
> > Cc: linux-security-module@vger.kernel.org
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > ---
> > include/linux/fs.h | 22 ++++++++++++++++++++++
> > security/apparmor/include/file.h | 18 ++++--------------
> > 2 files changed, 26 insertions(+), 14 deletions(-)
> >
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index 9eced4cc286e..814f10d4132e 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -993,6 +993,28 @@ static inline struct file *get_file(struct file *f)
> > #define get_file_rcu(x) atomic_long_inc_not_zero(&(x)->f_count)
> > #define file_count(x) atomic_long_read(&(x)->f_count)
> >
> > +/* Calculate the basic MAY_* flags needed for a given file. */
> > +static inline u8 file_to_perms(struct file *file)
>
> As long as there aren't multiple users of this and especially none in
> the vfs proper please don't move this into fs.h. It's overloaded enough
> as it is and we have vague plans on splitting it further in the future.

Sure -- this can live in a security .h file somewhere.

--
Kees Cook