3 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index de0e7719d4c5..12cb8bd81d2d 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -18,6 +18,8 @@ struct proc_ns_operations {
         struct ns_common *(*get)(struct task_struct *task);
         void (*put)(struct ns_common *ns);
         int (*install)(struct nsproxy *nsproxy, struct ns_common *ns);
+        struct user_namespace *(*owner)(struct ns_common *ns);
+        struct ns_common *(*get_parent)(struct ns_common *ns);
 };
 
 extern const struct proc_ns_operations netns_operations;
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 30ffe10cda18..eb209d4523f5 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -106,6 +106,8 @@ extern ssize_t proc_setgroups_write(struct file *, const char __user *, size_t,
 extern int proc_setgroups_show(struct seq_file *m, void *v);
 extern bool userns_may_setgroups(const struct user_namespace *ns);
 extern bool current_in_userns(const struct user_namespace *target_ns);
+
+struct ns_common *ns_get_owner(struct ns_common *ns);
 #else
 
 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
@@ -139,6 +141,11 @@ static inline bool current_in_userns(const struct user_namespace *target_ns)
 {
         return true;
 }
+
+static inline struct ns_common *ns_get_owner(struct ns_common *ns)
+{
+        return ERR_PTR(-EPERM);
+}
 #endif
 
 #endif /* _LINUX_USER_H */
diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h
new file mode 100644
index 000000000000..3af617230d1b
--- /dev/null
+++ b/include/uapi/linux/nsfs.h
@@ -0,0 +1,13 @@
+#ifndef __LINUX_NSFS_H
+#define __LINUX_NSFS_H
+
+#include <linux/ioctl.h>
+
+#define NSIO    0xb7
+
+/* Returns a file descriptor that refers to an owning user namespace */
+#define NS_GET_USERNS   _IO(NSIO, 0x1)
+/* Returns a file descriptor that refers to a parent namespace */
+#define NS_GET_PARENT   _IO(NSIO, 0x2)
+
+#endif /* __LINUX_NSFS_H */