1#ifndef _LINUX_USER_NAMESPACE_H
2#define _LINUX_USER_NAMESPACE_H
3
4#include <linux/kref.h>
5#include <linux/nsproxy.h>
6#include <linux/sched.h>
7#include <linux/err.h>
8
9#define UIDHASH_BITS	(CONFIG_BASE_SMALL ? 3 : 8)
10#define UIDHASH_SZ	(1 << UIDHASH_BITS)
11
12struct user_namespace {
13	struct kref		kref;
14	struct hlist_head	uidhash_table[UIDHASH_SZ];
15	struct user_struct	*root_user;
16};
17
18extern struct user_namespace init_user_ns;
19
20#ifdef CONFIG_USER_NS
21
22static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
23{
24	if (ns)
25		kref_get(&ns->kref);
26	return ns;
27}
28
29extern struct user_namespace *copy_user_ns(int flags,
30					   struct user_namespace *old_ns);
31extern void free_user_ns(struct kref *kref);
32
33static inline void put_user_ns(struct user_namespace *ns)
34{
35	if (ns)
36		kref_put(&ns->kref, free_user_ns);
37}
38
39#else
40
41static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
42{
43	return &init_user_ns;
44}
45
46static inline struct user_namespace *copy_user_ns(int flags,
47						  struct user_namespace *old_ns)
48{
49	if (flags & CLONE_NEWUSER)
50		return ERR_PTR(-EINVAL);
51
52	return old_ns;
53}
54
55static inline void put_user_ns(struct user_namespace *ns)
56{
57}
58
59#endif
60
61#endif /* _LINUX_USER_H */
62