include/linux/user_namespace.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_USER_NAMESPACE_H
   3 #define _LINUX_USER_NAMESPACE_H
   4
   5 #include <linux/kref.h>
   6 #include <linux/nsproxy.h>
   7 #include <linux/ns_common.h>
   8 #include <linux/sched.h>
   9 #include <linux/workqueue.h>
  10 #include <linux/rwsem.h>
  11 #include <linux/sysctl.h>
  12 #include <linux/err.h>
  13
  14 #define UID_GID_MAP_MAX_BASE_EXTENTS 5
  15 #define UID_GID_MAP_MAX_EXTENTS 340
  16
  17 struct uid_gid_extent {
  18         u32 first;
  19         u32 lower_first;
  20         u32 count;
  21 };
  22
  23 struct uid_gid_map { /* 64 bytes -- 1 cache line */
  24         u32 nr_extents;
  25         union {
  26                 struct uid_gid_extent extent[UID_GID_MAP_MAX_BASE_EXTENTS];
  27                 struct {
  28                         struct uid_gid_extent *forward;
  29                         struct uid_gid_extent *reverse;
  30                 };
  31         };
  32 };
  33
  34 #define USERNS_SETGROUPS_ALLOWED 1UL
  35
  36 #define USERNS_INIT_FLAGS USERNS_SETGROUPS_ALLOWED
  37
  38 struct ucounts;
  39
  40 enum ucount_type {
  41         UCOUNT_USER_NAMESPACES,
  42         UCOUNT_PID_NAMESPACES,
  43         UCOUNT_UTS_NAMESPACES,
  44         UCOUNT_IPC_NAMESPACES,
  45         UCOUNT_NET_NAMESPACES,
  46         UCOUNT_MNT_NAMESPACES,
  47         UCOUNT_CGROUP_NAMESPACES,
  48         UCOUNT_TIME_NAMESPACES,
  49 #ifdef CONFIG_INOTIFY_USER
  50         UCOUNT_INOTIFY_INSTANCES,
  51         UCOUNT_INOTIFY_WATCHES,
  52 #endif
  53 #ifdef CONFIG_FANOTIFY
  54         UCOUNT_FANOTIFY_GROUPS,
  55         UCOUNT_FANOTIFY_MARKS,
  56 #endif
  57         UCOUNT_COUNTS,
  58 };
  59
  60 struct user_namespace {
  61         struct uid_gid_map      uid_map;
  62         struct uid_gid_map      gid_map;
  63         struct uid_gid_map      projid_map;
  64         struct user_namespace   *parent;
  65         int                     level;
  66         kuid_t                  owner;
  67         kgid_t                  group;
  68         struct ns_common        ns;
  69         unsigned long           flags;
  70         /* parent_could_setfcap: true if the creator if this ns had CAP_SETFCAP
  71          * in its effective capability set at the child ns creation time. */
  72         bool                    parent_could_setfcap;
  73
  74 #ifdef CONFIG_KEYS
  75         /* List of joinable keyrings in this namespace.  Modification access of
  76          * these pointers is controlled by keyring_sem.  Once
  77          * user_keyring_register is set, it won't be changed, so it can be
  78          * accessed directly with READ_ONCE().
  79          */
  80         struct list_head        keyring_name_list;
  81         struct key              *user_keyring_register;
  82         struct rw_semaphore     keyring_sem;
  83 #endif
  84
  85         /* Register of per-UID persistent keyrings for this namespace */
  86 #ifdef CONFIG_PERSISTENT_KEYRINGS
  87         struct key              *persistent_keyring_register;
  88 #endif
  89         struct work_struct      work;
  90 #ifdef CONFIG_SYSCTL
  91         struct ctl_table_set    set;
  92         struct ctl_table_header *sysctls;
  93 #endif
  94         struct ucounts          *ucounts;
  95         int ucount_max[UCOUNT_COUNTS];
  96 } __randomize_layout;
  97
  98 struct ucounts {
  99         struct hlist_node node;
 100         struct user_namespace *ns;
 101         kuid_t uid;
 102         int count;
 103         atomic_t ucount[UCOUNT_COUNTS];
 104 };
 105
 106 extern struct user_namespace init_user_ns;
 107
 108 bool setup_userns_sysctls(struct user_namespace *ns);
 109 void retire_userns_sysctls(struct user_namespace *ns);
 110 struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid, enum ucount_type type);
 111 void dec_ucount(struct ucounts *ucounts, enum ucount_type type);
 112
 113 #ifdef CONFIG_USER_NS
 114
 115 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
 116 {
 117         if (ns)
 118                 refcount_inc(&ns->ns.count);
 119         return ns;
 120 }
 121
 122 extern int create_user_ns(struct cred *new);
 123 extern int unshare_userns(unsigned long unshare_flags, struct cred **new_cred);
 124 extern void __put_user_ns(struct user_namespace *ns);
 125
 126 static inline void put_user_ns(struct user_namespace *ns)
 127 {
 128         if (ns && refcount_dec_and_test(&ns->ns.count))
 129                 __put_user_ns(ns);
 130 }
 131
 132 struct seq_operations;
 133 extern const struct seq_operations proc_uid_seq_operations;
 134 extern const struct seq_operations proc_gid_seq_operations;
 135 extern const struct seq_operations proc_projid_seq_operations;
 136 extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *);
 137 extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *);
 138 extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *);
 139 extern ssize_t proc_setgroups_write(struct file *, const char __user *, size_t, loff_t *);
 140 extern int proc_setgroups_show(struct seq_file *m, void *v);
 141 extern bool userns_may_setgroups(const struct user_namespace *ns);
 142 extern bool in_userns(const struct user_namespace *ancestor,
 143                        const struct user_namespace *child);
 144 extern bool current_in_userns(const struct user_namespace *target_ns);
 145 struct ns_common *ns_get_owner(struct ns_common *ns);
 146 #else
 147
 148 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
 149 {
 150         return &init_user_ns;
 151 }
 152
 153 static inline int create_user_ns(struct cred *new)
 154 {
 155         return -EINVAL;
 156 }
 157
 158 static inline int unshare_userns(unsigned long unshare_flags,
 159                                  struct cred **new_cred)
 160 {
 161         if (unshare_flags & CLONE_NEWUSER)
 162                 return -EINVAL;
 163         return 0;
 164 }
 165
 166 static inline void put_user_ns(struct user_namespace *ns)
 167 {
 168 }
 169
 170 static inline bool userns_may_setgroups(const struct user_namespace *ns)
 171 {
 172         return true;
 173 }
 174
 175 static inline bool in_userns(const struct user_namespace *ancestor,
 176                              const struct user_namespace *child)
 177 {
 178         return true;
 179 }
 180
 181 static inline bool current_in_userns(const struct user_namespace *target_ns)
 182 {
 183         return true;
 184 }
 185
 186 static inline struct ns_common *ns_get_owner(struct ns_common *ns)
 187 {
 188         return ERR_PTR(-EPERM);
 189 }
 190 #endif
 191
 192 #endif /* _LINUX_USER_H */