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

[Stephen Smalley]

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.

>                 }
> -               rc = -EINVAL;
> -               pr_warn("SELinux: Unable to set superblock options "
> -                       "before the security server is initialized\n");

Ditto.

>                 goto out;
>         }
>
>