root/include/linux/user_namespace.h

INCLUDED FROM

DEFINITIONS

1. get_user_ns
2. put_user_ns
3. get_user_ns
4. create_user_ns
5. unshare_userns
6. put_user_ns
7. userns_may_setgroups

#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];
};

#define USERNS_SETGROUPS_ALLOWED 1UL

#define USERNS_INIT_FLAGS USERNS_SETGROUPS_ALLOWED

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;
        unsigned long           flags;

        /* 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 const struct seq_operations proc_uid_seq_operations;
extern const struct seq_operations proc_gid_seq_operations;
extern const 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 *);
extern ssize_t proc_setgroups_write(struct file *, const char __user *, size_t, loff_t *);
extern int proc_setgroups_show(struct seq_file *m, void *v);
extern bool userns_may_setgroups(const struct user_namespace *ns);
#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)
{
}

static inline bool userns_may_setgroups(const struct user_namespace *ns)
{
        return true;
}
#endif

#endif /* _LINUX_USER_H */