[PATCH v3 2/5] capability: Add new capable_noaudit

[Carlos Maiolino]

On Thu, Jul 02, 2026 at 08:56:05AM -0700, Darrick J. Wong wrote:
> On Thu, Jul 02, 2026 at 11:33:19AM +0200, cem at kernel.org wrote:
> > From: Carlos Maiolino <cem at kernel.org>
> > 
> > In some situations (quota enforcement bypass in this case) we'd like to
> > check for a specific capability without triggering spurious audit
> > messages from security modules like selinux.
> > 
> > Add a new helper so we don't need to use ns_capable_noaudit() directly.
> > 
> > V3: remove the extern declaration
> > 
> > Signed-off-by: Carlos Maiolino <cmaiolino at redhat.com>
> > Cc: Jan Kara <jack at suse.cz>
> > Cc: Darrick J. Wong <djwong at kernel.org>
> > Cc: Dave Chinner <david at fromorbit.com>
> > Cc: Eric Sandeen <sandeen at redhat.com>
> > Cc: Dr. Thomas Orgis" <thomas.orgis at uni-hamburg.de>
> > Cc: linux-xfs at vger.kernel.org
> > Cc: linux-fsdevel at vger.kernel.org
> > Cc: linux-security-module at vger.kernel.org
> > Cc: linux-kernel at vger.kernel.org
> > Reviewed-by: Christoph Hellwig <hch at lst.de>
> > Reviewed-by: Serge Hallyn <serge at hallyn.com>
> > ---
> >  include/linux/capability.h |  5 +++++
> >  kernel/capability.c        | 17 +++++++++++++++++
> >  2 files changed, 22 insertions(+)
> > 
> > diff --git a/include/linux/capability.h b/include/linux/capability.h
> > index 37db92b3d6f8..f8532d92fcad 100644
> > --- a/include/linux/capability.h
> > +++ b/include/linux/capability.h
> > @@ -145,6 +145,7 @@ extern bool has_capability_noaudit(struct task_struct *t, int cap);
> >  extern bool has_ns_capability_noaudit(struct task_struct *t,
> >  				      struct user_namespace *ns, int cap);
> >  extern bool capable(int cap);
> > +bool capable_noaudit(int cap);
> >  extern bool ns_capable(struct user_namespace *ns, int cap);
> >  extern bool ns_capable_noaudit(struct user_namespace *ns, int cap);
> >  extern bool ns_capable_setid(struct user_namespace *ns, int cap);
> > @@ -167,6 +168,10 @@ static inline bool capable(int cap)
> >  {
> >  	return true;
> >  }
> > +static inline bool capable_noaudit(int cap)
> > +{
> > +	return true;
> > +}
> >  static inline bool ns_capable(struct user_namespace *ns, int cap)
> >  {
> >  	return true;
> > diff --git a/kernel/capability.c b/kernel/capability.c
> > index 829f49ae07b9..2c2d1e8300bd 100644
> > --- a/kernel/capability.c
> > +++ b/kernel/capability.c
> > @@ -416,6 +416,23 @@ bool capable(int cap)
> >  	return ns_capable(&init_user_ns, cap);
> >  }
> >  EXPORT_SYMBOL(capable);
> > +
> > +/**
> > + * capable_noaudit - Determine if the current task has a superior
> > + * capability in effect (unaudited).
> > + * @cap: The capability to be tested for
> > + *
> > + * This is the same as capable(), except it uses CAP_OPT_NOAUDIT as to prevent
> > + * issuing spurious audit messages.
> > + *
> > + * This sets PF_SUPERPRIV on the task if the capability is available on the
> > + * assumption that it's about to be used.
> 
> Same complaint about the documentation as last time:
> https://lore.kernel.org/linux-fsdevel/20260626151656.GT6078@frogsfrogsfrogs/

Right. I assumed "capability in effect" would suffice that, but I can
add some extra comment here.

> 
> --D
> 
> > + */
> > +bool capable_noaudit(int cap)
> > +{
> > +	return ns_capable_noaudit(&init_user_ns, cap);
> > +}
> > +EXPORT_SYMBOL(capable_noaudit);
> >  #endif /* CONFIG_MULTIUSER */
> >  
> >  /**
> > -- 
> > 2.54.0
> > 
> > 
>