4 files changed, 62 insertions, 1 deletions

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 276ccaa2670c..cab741c2d603 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -8,6 +8,7 @@
 #include <linux/lockdep.h>
 #include <linux/ipc.h>
 #include <linux/pid_namespace.h>
+#include <linux/user_namespace.h>
 
 #define INIT_FDTABLE \
 {                                                       \
@@ -78,6 +79,7 @@ extern struct nsproxy init_nsproxy;
         .uts_ns         = &init_uts_ns,                                 \
         .mnt_ns         = NULL,                                         \
         INIT_IPC_NS(ipc_ns)                                             \
+        .user_ns        = &init_user_ns,                                \
 }
 
 #define INIT_SIGHAND(sighand) {                                         \
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 189e0dc993ab..6d179a397bfb 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -28,6 +28,7 @@ struct nsproxy {
         struct ipc_namespace *ipc_ns;
         struct mnt_namespace *mnt_ns;
         struct pid_namespace *pid_ns;
+        struct user_namespace *user_ns;
 };
 extern struct nsproxy init_nsproxy;
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index b579624477f4..c667255d70db 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -287,6 +287,7 @@ extern signed long schedule_timeout_uninterruptible(signed long timeout);
 asmlinkage void schedule(void);
 
 struct nsproxy;
+struct user_namespace;
 
 /* Maximum number of active map areas.. This is a random (large) number */
 #define DEFAULT_MAX_MAP_COUNT   65536
@@ -1408,7 +1409,7 @@ extern struct task_struct *find_task_by_pid_type(int type, int pid);
 extern void __set_special_pids(pid_t session, pid_t pgrp);
 
 /* per-UID process charging. */
-extern struct user_struct * alloc_uid(uid_t);
+extern struct user_struct * alloc_uid(struct user_namespace *, uid_t);
 static inline struct user_struct *get_uid(struct user_struct *u)
 {
         atomic_inc(&u->__count);
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
new file mode 100644
index 000000000000..92a45867ecfb
--- /dev/null
+++ b/include/linux/user_namespace.h
@@ -0,0 +1,57 @@
+#ifndef _LINUX_USER_NAMESPACE_H
+#define _LINUX_USER_NAMESPACE_H
+
+#include <linux/kref.h>
+#include <linux/nsproxy.h>
+#include <linux/sched.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)
+{
+        return NULL;
+}
+
+static inline void put_user_ns(struct user_namespace *ns)
+{
+}
+
+#endif
+
+#endif /* _LINUX_USER_H */