1 files changed, 61 insertions, 0 deletions

diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
new file mode 100644
index 000000000000..bb320573bb9e
--- /dev/null
+++ b/include/linux/user_namespace.h
@@ -0,0 +1,61 @@
+#ifndef _LINUX_USER_NAMESPACE_H
+#define _LINUX_USER_NAMESPACE_H
+
+#include <linux/kref.h>
+#include <linux/nsproxy.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+
+#define UIDHASH_BITS    (CONFIG_BASE_SMALL ? 3 : 8)
+#define UIDHASH_SZ      (1 << UIDHASH_BITS)
+
+struct user_namespace {
+        struct kref             kref;
+        struct list_head        uidhash_table[UIDHASH_SZ];
+        struct user_struct      *root_user;
+};
+
+extern struct user_namespace init_user_ns;
+
+#ifdef CONFIG_USER_NS
+
+static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
+{
+        if (ns)
+                kref_get(&ns->kref);
+        return ns;
+}
+
+extern struct user_namespace *copy_user_ns(int flags,
+                                           struct user_namespace *old_ns);
+extern void free_user_ns(struct kref *kref);
+
+static inline void put_user_ns(struct user_namespace *ns)
+{
+        if (ns)
+                kref_put(&ns->kref, free_user_ns);
+}
+
+#else
+
+static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
+{
+        return &init_user_ns;
+}
+
+static inline struct user_namespace *copy_user_ns(int flags,
+                                                  struct user_namespace *old_ns)
+{
+        if (flags & CLONE_NEWUSER)
+                return ERR_PTR(-EINVAL);
+
+        return NULL;
+}
+
+static inline void put_user_ns(struct user_namespace *ns)
+{
+}
+
+#endif
+
+#endif /* _LINUX_USER_H */