Merge tag 'docs-4.14' of git://git.lwn.net/linux

[sfrench/cifs-2.6.git] / kernel / user_namespace.c

diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 2f735cbe05e8aca3b8ee8a3dcc7de493f9757c05..c490f1e4313b998a60686b98fbdf6b0167753e11 100644 (file)
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -986,17 +986,21 @@ bool userns_may_setgroups(const struct user_namespace *ns)
 }
 
 /*
- * Returns true if @ns is the same namespace as or a descendant of
- * @target_ns.
+ * Returns true if @child is the same namespace or a descendant of
+ * @ancestor.
  */
+bool in_userns(const struct user_namespace *ancestor,
+              const struct user_namespace *child)
+{
+       const struct user_namespace *ns;
+       for (ns = child; ns->level > ancestor->level; ns = ns->parent)
+               ;
+       return (ns == ancestor);
+}
+
 bool current_in_userns(const struct user_namespace *target_ns)
 {
-       struct user_namespace *ns;
-       for (ns = current_user_ns(); ns; ns = ns->parent) {
-               if (ns == target_ns)
-                       return true;
-       }
-       return false;
+       return in_userns(target_ns, current_user_ns());
 }
 
 static inline struct user_namespace *to_user_ns(struct ns_common *ns)