include/linux/user_namespace.h

   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
  12 struct user_namespace {
  13         struct kref             kref;
  14         struct hlist_head       uidhash_table[UIDHASH_SZ];
  15         struct user_struct      *creator;
  16         struct work_struct      destroyer;
  17 };
  18
  19 extern struct user_namespace init_user_ns;
  20
  21 #ifdef CONFIG_USER_NS
  22
  23 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
  24 {
  25         if (ns)
  26                 kref_get(&ns->kref);
  27         return ns;
  28 }
  29
  30 extern int create_user_ns(struct cred *new);
  31 extern void free_user_ns(struct kref *kref);
  32
  33 static inline void put_user_ns(struct user_namespace *ns)
  34 {
  35         if (ns)
  36                 kref_put(&ns->kref, free_user_ns);
  37 }
  38
  39 uid_t user_ns_map_uid(struct user_namespace *to, const struct cred *cred, uid_t uid);
  40 gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t gid);
  41
  42 #else
  43
  44 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
  45 {
  46         return &init_user_ns;
  47 }
  48
  49 static inline int create_user_ns(struct cred *new)
  50 {
  51         return -EINVAL;
  52 }
  53
  54 static inline void put_user_ns(struct user_namespace *ns)
  55 {
  56 }
  57
  58 static inline uid_t user_ns_map_uid(struct user_namespace *to,
  59         const struct cred *cred, uid_t uid)
  60 {
  61         return uid;
  62 }
  63 static inline gid_t user_ns_map_gid(struct user_namespace *to,
  64         const struct cred *cred, gid_t gid)
  65 {
  66         return gid;
  67 }
  68
  69 #endif
  70
  71 #endif /* _LINUX_USER_H */