#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 UID_GID_MAP_MAX_EXTENTS 5

struct uid_gid_map { /* 64 bytes -- 1 cache line */
u32 nr_extents;
struct uid_gid_extent {
u32 first;
u32 lower_first;
u32 count;
} extent[UID_GID_MAP_MAX_EXTENTS];
};

struct user_namespace {
struct uid_gid_map uid_map;
struct uid_gid_map gid_map;
struct uid_gid_map projid_map;
atomic_t count;
struct user_namespace *parent;
int level;
kuid_t owner;
kgid_t group;
unsigned int proc_inum;

/* Register of per-UID persistent keyrings for this namespace */
#ifdef CONFIG_PERSISTENT_KEYRINGS
struct key *persistent_keyring_register;
struct rw_semaphore persistent_keyring_register_sem;
#endif
};

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)
atomic_inc(&ns->count);
return ns;
}

extern int create_user_ns(struct cred *new);
extern int unshare_userns(unsigned long unshare_flags, struct cred **new_cred);
extern void free_user_ns(struct user_namespace *ns);

static inline void put_user_ns(struct user_namespace *ns)
{
if (ns && atomic_dec_and_test(&ns->count))
free_user_ns(ns);
}

struct seq_operations;
extern struct seq_operations proc_uid_seq_operations;
extern struct seq_operations proc_gid_seq_operations;
extern struct seq_operations proc_projid_seq_operations;
extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *);
extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *);
extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *);
#else

static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
{
return &init_user_ns;
}

static inline int create_user_ns(struct cred *new)
{
return -EINVAL;
}

static inline int unshare_userns(unsigned long unshare_flags,
struct cred **new_cred)
{
if (unshare_flags & CLONE_NEWUSER)
return -EINVAL;
return 0;
}

static inline void put_user_ns(struct user_namespace *ns)
{
}

#endif

#endif /* _LINUX_USER_H */