Re: [PATCH v1 05/11] landlock: Move filesystem helpers and add a new one

[Mickaël Salaün]

On 17/03/2022 02:26, Paul Moore wrote:
> On Mon, Feb 21, 2022 at 4:15 PM Mickaël Salaün <mic@xxxxxxxxxxx> wrote:
> > From: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx>
> >
> > Move the SB_NOUSER and IS_PRIVATE dentry check to a standalone
> > is_nouser_or_private() helper.  This will be useful for a following
> > commit.
> >
> > Move get_mode_access() and maybe_remove() to make them usable by new
> > code provided by a following commit.
> >
> > Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx>
> > Link: https://lore.kernel.org/r/20220221212522.320243-6-mic@xxxxxxxxxxx
> > ---
> >   security/landlock/fs.c | 87 ++++++++++++++++++++++--------------------
> >   1 file changed, 46 insertions(+), 41 deletions(-)
>
> One nit-picky comment below, otherwise it looks fine to me.
>
> Reviewed-by: Paul Moore <paul@xxxxxxxxxxxxxx>
>
> > diff --git a/security/landlock/fs.c b/security/landlock/fs.c
> > index 9662f9fb3cd0..3886f9ad1a60 100644
> > --- a/security/landlock/fs.c
> > +++ b/security/landlock/fs.c
> > @@ -257,6 +257,18 @@ static inline bool unmask_layers(const struct landlock_rule *const rule,
> >          return false;
> >   }
> >
> > +static inline bool is_nouser_or_private(const struct dentry *dentry)
> > +{
> > +       /*
> > +        * Allows access to pseudo filesystems that will never be mountable
> > +        * (e.g. sockfs, pipefs), but can still be reachable through
> > +        * /proc/<pid>/fd/<file-descriptor> .
> > +        */
>
> I might suggest moving this explanation up to a function header comment block.

Sounds good.


> > +       return (dentry->d_sb->s_flags & SB_NOUSER) ||
> > +                       (d_is_positive(dentry) &&
> > +                        unlikely(IS_PRIVATE(d_backing_inode(dentry))));
> > +}
> > +
> >   static int check_access_path(const struct landlock_ruleset *const domain,
> >                  const struct path *const path,
> >                  const access_mask_t access_request)
>
> --
> paul-moore.com