On Wed, Nov 14, 2018 at 2:47 PM Paul Moore <paul@xxxxxxxxxxxxxx> wrote:
> Commit 95ffe194204a ("selinux: refactor mls_context_to_sid() and make
> it stricter") inadvertently changed how we handle labels that did not
> contain MLS information. This patch restores the proper behavior in
> mls_context_to_sid() and adds a comment explaining the proper
> behavior to help ensure this doesn't happen again.
>
> Fixes: 95ffe194204a ("selinux: refactor mls_context_to_sid() and make it stricter")
> Reported-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
> Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
> ---
> security/selinux/ss/mls.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
Building a test kernel now, assuming all goes well I'll merge this
into selinux/stable-4.20 and send it to Linus this week.
> diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c
> index 2fe459df3c85..b7efa2296969 100644
> --- a/security/selinux/ss/mls.c
> +++ b/security/selinux/ss/mls.c
> @@ -245,9 +245,13 @@ int mls_context_to_sid(struct policydb *pol,
> char *rangep[2];
>
> if (!pol->mls_enabled) {
> - if ((def_sid != SECSID_NULL && oldc) || (*scontext) == '\0')
> - return 0;
> - return -EINVAL;
> + /*
> + * With no MLS, only return -EINVAL if there is a MLS field
> + * and it did not come from an xattr.
> + */
> + if (oldc && def_sid == SECSID_NULL)
> + return -EINVAL;
> + return 0;
> }
>
> /*
>
--
paul moore
www.paul-moore.com
