Re: [PATCH] selinux: replace BUG_ONs with WARN_ONs in avc.c

From: Ondrej Mosnacek <omosnace@redhat.com>
To: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>, selinux@vger.kernel.org
Subject: Re: [PATCH] selinux: replace BUG_ONs with WARN_ONs in avc.c
Date: Mon, 28 Jan 2019 16:43:06 +0100	[thread overview]
Message-ID: <CAFqZXNsVOZi9DO9qgdvmhgtw2iKxXovpdjLzYkuLJ2M72jyVaA@mail.gmail.com> (raw)
In-Reply-To: <CAHC9VhQuFPQ9C5=FxP1LEetZVHRsfmQV2qH5TErTaPuBW9wcsQ@mail.gmail.com>

On Mon, Jan 28, 2019 at 4:11 PM Paul Moore <paul@paul-moore.com> wrote:
> On Mon, Jan 28, 2019 at 8:23 AM Stephen Smalley <sds@tycho.nsa.gov> wrote:
> > On 1/26/19 5:18 AM, Ondrej Mosnacek wrote:
> > > These checks are only guarding against programming errors that could
> > > silently grant too many permissions. These cases are better handled with
> > > WARN_ON(), since it doesn't really help much to crash the machine in
> > > this case.
> > >
> > > Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
> > > ---
> > >   security/selinux/avc.c | 4 ++--
> > >   1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/security/selinux/avc.c b/security/selinux/avc.c
> > > index 3a27418b20d7..84f108f4100a 100644
> > > --- a/security/selinux/avc.c
> > > +++ b/security/selinux/avc.c
> > > @@ -1059,7 +1059,7 @@ int avc_has_extended_perms(struct selinux_state *state,
> > >       int rc = 0, rc2;
> > >
> > >       xp_node = &local_xp_node;
> > > -     BUG_ON(!requested);
> > > +     WARN_ON(!requested);
> >
> > Should this be:
> >         if (WARN_ON(!requested))
> >                 return -EACCES;
>
> I think so, it would be bad not to return an error in this case (and
> the similar one below).

Makes sense... will send a v2 right away.

>
> > >
> > >       rcu_read_lock();
> > >
> > > @@ -1149,7 +1149,7 @@ inline int avc_has_perm_noaudit(struct selinux_state *state,
> > >       int rc = 0;
> > >       u32 denied;
> > >
> > > -     BUG_ON(!requested);
> > > +     WARN_ON(!requested);
> >
> > And likewise
> >
> > >
> > >       rcu_read_lock();
> > >
> > >
>
> --
> paul moore
> www.paul-moore.com

-- 
Ondrej Mosnacek <omosnace at redhat dot com>
Associate Software Engineer, Security Technologies
Red Hat, Inc.