selinux: fix non-MLS handling in mls_context_to_sid()

Commit 95ffe19 ("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: 95ffe19 ("selinux: refactor mls_context_to_sid() and make it stricter") Reported-by: Stephen Smalley <[email protected]> Signed-off-by: Paul Moore <[email protected]>
broSysX64 · Nov 14, 2018 · 877181a · 877181a
1 parent c138325
commit 877181a
Showing 1 changed file with 7 additions and 3 deletions.
diff --git 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;
 	}
 
 	/*