[PATCH v2 2/2] LSM: Infrastructure management of the mnt_opts security blob

[Paul Moore]

On Thu, Oct 9, 2025 at 2:38 PM Stephen Smalley
<stephen.smalley.work at gmail.com> wrote:
> On Thu, Sep 25, 2025 at 1:12 PM Casey Schaufler <casey at schaufler-ca.com> wrote:
> >
> > Move management of the mnt_opts->security blob out of the individual
> > security modules and into the security infrastructure.  The modules
> > tell the infrastructure how much space is required, and the space is
> > allocated as required in the interfaces that use the blob.
> >
> > Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
> > ---
>
> > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> > index 4bba9d119713..1ccf880e4894 100644
> > --- a/security/selinux/hooks.c
> > +++ b/security/selinux/hooks.c
> > @@ -656,19 +651,13 @@ static int selinux_set_mnt_opts(struct super_block *sb,
> >         mutex_lock(&sbsec->lock);
> >
> >         if (!selinux_initialized()) {
> > -               if (!opts) {
> > -                       /* Defer initialization until selinux_complete_init,
> > -                          after the initial policy is loaded and the security
> > -                          server is ready to handle calls. */
> > -                       if (kern_flags & SECURITY_LSM_NATIVE_LABELS) {
> > -                               sbsec->flags |= SE_SBNATIVE;
> > -                               *set_kern_flags |= SECURITY_LSM_NATIVE_LABELS;
> > -                       }
> > -                       goto out;
> > +               /* Defer initialization until selinux_complete_init,
> > +                  after the initial policy is loaded and the security
> > +                  server is ready to handle calls. */
> > +               if (kern_flags & SECURITY_LSM_NATIVE_LABELS) {
> > +                       sbsec->flags |= SE_SBNATIVE;
> > +                       *set_kern_flags |= SECURITY_LSM_NATIVE_LABELS;
>
> This seemingly would produce a change in behavior for SELinux.
> Previously we would only do this if there were no SELinux mount
> options specified.

What Stephen said.  I think this is good work that needs to be done
(thank you for doing it!), but we have to preserve existing behaviors.

-- 
paul-moore.com