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         UCOUNT_COUNTS,
  54 };
  55
  56 struct user_namespace {
  57         struct uid_gid_map      uid_map;
  58         struct uid_gid_map      gid_map;
  59         struct uid_gid_map      projid_map;
  60         atomic_t                count;
  61         struct user_namespace   *parent;
  62         int                     level;
  63         kuid_t                  owner;
  64         kgid_t                  group;
  65         struct ns_common        ns;
  66         unsigned long           flags;
  67
  68 #ifdef CONFIG_KEYS
  69         /* List of joinable keyrings in this namespace.  Modification access of
  70          * these pointers is controlled by keyring_sem.  Once
  71          * user_keyring_register is set, it won't be changed, so it can be
  72          * accessed directly with READ_ONCE().
  73          */
  74         struct list_head        keyring_name_list;
  75         struct key              *user_keyring_register;
  76         struct rw_semaphore     keyring_sem;
  77 #endif
  78
  79         /* Register of per-UID persistent keyrings for this namespace */
  80 #ifdef CONFIG_PERSISTENT_KEYRINGS
  81         struct key              *persistent_keyring_register;
  82 #endif
  83         struct work_struct      work;
  84 #ifdef CONFIG_SYSCTL
  85         struct ctl_table_set    set;
  86         struct ctl_table_header *sysctls;
  87 #endif
  88         struct ucounts          *ucounts;
  89         int ucount_max[UCOUNT_COUNTS];
  90 } __randomize_layout;
  91
  92 struct ucounts {
  93         struct hlist_node node;
  94         struct user_namespace *ns;
  95         kuid_t uid;
  96         int count;
  97         atomic_t ucount[UCOUNT_COUNTS];
  98 };
  99
 100 extern struct user_namespace init_user_ns;
 101
 102 bool setup_userns_sysctls(struct user_namespace *ns);
 103 void retire_userns_sysctls(struct user_namespace *ns);
 104 struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid, enum ucount_type type);
 105 void dec_ucount(struct ucounts *ucounts, enum ucount_type type);
 106
 107 #ifdef CONFIG_USER_NS
 108
 109 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
 110 {
 111         if (ns)
 112                 atomic_inc(&ns->count);
 113         return ns;
 114 }
 115
 116 extern int create_user_ns(struct cred *new);
 117 extern int unshare_userns(unsigned long unshare_flags, struct cred **new_cred);
 118 extern void __put_user_ns(struct user_namespace *ns);
 119
 120 static inline void put_user_ns(struct user_namespace *ns)
 121 {
 122         if (ns && atomic_dec_and_test(&ns->count))
 123                 __put_user_ns(ns);
 124 }
 125
 126 struct seq_operations;
 127 extern const struct seq_operations proc_uid_seq_operations;
 128 extern const struct seq_operations proc_gid_seq_operations;
 129 extern const struct seq_operations proc_projid_seq_operations;
 130 extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *);
 131 extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *);
 132 extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *);
 133 extern ssize_t proc_setgroups_write(struct file *, const char __user *, size_t, loff_t *);
 134 extern int proc_setgroups_show(struct seq_file *m, void *v);
 135 extern bool userns_may_setgroups(const struct user_namespace *ns);
 136 extern bool in_userns(const struct user_namespace *ancestor,
 137                        const struct user_namespace *child);
 138 extern bool current_in_userns(const struct user_namespace *target_ns);
 139 struct ns_common *ns_get_owner(struct ns_common *ns);
 140 #else
 141
 142 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
 143 {
 144         return &init_user_ns;
 145 }
 146
 147 static inline int create_user_ns(struct cred *new)
 148 {
 149         return -EINVAL;
 150 }
 151
 152 static inline int unshare_userns(unsigned long unshare_flags,
 153                                  struct cred **new_cred)
 154 {
 155         if (unshare_flags & CLONE_NEWUSER)
 156                 return -EINVAL;
 157         return 0;
 158 }
 159
 160 static inline void put_user_ns(struct user_namespace *ns)
 161 {
 162 }
 163
 164 static inline bool userns_may_setgroups(const struct user_namespace *ns)
 165 {
 166         return true;
 167 }
 168
 169 static inline bool in_userns(const struct user_namespace *ancestor,
 170                              const struct user_namespace *child)
 171 {
 172         return true;
 173 }
 174
 175 static inline bool current_in_userns(const struct user_namespace *target_ns)
 176 {
 177         return true;
 178 }
 179
 180 static inline struct ns_common *ns_get_owner(struct ns_common *ns)
 181 {
 182         return ERR_PTR(-EPERM);
 183 }
 184 #endif
 185
 186 #endif /* _LINUX_USER_H */