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         union {
  25                 struct {
  26                         struct uid_gid_extent extent[UID_GID_MAP_MAX_BASE_EXTENTS];
  27                         u32 nr_extents;
  28                 };
  29                 struct {
  30                         struct uid_gid_extent *forward;
  31                         struct uid_gid_extent *reverse;
  32                 };
  33         };
  34 };
  35
  36 #define USERNS_SETGROUPS_ALLOWED 1UL
  37
  38 #define USERNS_INIT_FLAGS USERNS_SETGROUPS_ALLOWED
  39
  40 struct ucounts;
  41
  42 enum ucount_type {
  43         UCOUNT_USER_NAMESPACES,
  44         UCOUNT_PID_NAMESPACES,
  45         UCOUNT_UTS_NAMESPACES,
  46         UCOUNT_IPC_NAMESPACES,
  47         UCOUNT_NET_NAMESPACES,
  48         UCOUNT_MNT_NAMESPACES,
  49         UCOUNT_CGROUP_NAMESPACES,
  50         UCOUNT_TIME_NAMESPACES,
  51 #ifdef CONFIG_INOTIFY_USER
  52         UCOUNT_INOTIFY_INSTANCES,
  53         UCOUNT_INOTIFY_WATCHES,
  54 #endif
  55 #ifdef CONFIG_FANOTIFY
  56         UCOUNT_FANOTIFY_GROUPS,
  57         UCOUNT_FANOTIFY_MARKS,
  58 #endif
  59         UCOUNT_COUNTS,
  60 };
  61
  62 enum rlimit_type {
  63         UCOUNT_RLIMIT_NPROC,
  64         UCOUNT_RLIMIT_MSGQUEUE,
  65         UCOUNT_RLIMIT_SIGPENDING,
  66         UCOUNT_RLIMIT_MEMLOCK,
  67         UCOUNT_RLIMIT_COUNTS,
  68 };
  69
  70 #if IS_ENABLED(CONFIG_BINFMT_MISC)
  71 struct binfmt_misc;
  72 #endif
  73
  74 struct user_namespace {
  75         struct uid_gid_map      uid_map;
  76         struct uid_gid_map      gid_map;
  77         struct uid_gid_map      projid_map;
  78         struct user_namespace   *parent;
  79         int                     level;
  80         kuid_t                  owner;
  81         kgid_t                  group;
  82         struct ns_common        ns;
  83         unsigned long           flags;
  84         /* parent_could_setfcap: true if the creator if this ns had CAP_SETFCAP
  85          * in its effective capability set at the child ns creation time. */
  86         bool                    parent_could_setfcap;
  87
  88 #ifdef CONFIG_KEYS
  89         /* List of joinable keyrings in this namespace.  Modification access of
  90          * these pointers is controlled by keyring_sem.  Once
  91          * user_keyring_register is set, it won't be changed, so it can be
  92          * accessed directly with READ_ONCE().
  93          */
  94         struct list_head        keyring_name_list;
  95         struct key              *user_keyring_register;
  96         struct rw_semaphore     keyring_sem;
  97 #endif
  98
  99         /* Register of per-UID persistent keyrings for this namespace */
 100 #ifdef CONFIG_PERSISTENT_KEYRINGS
 101         struct key              *persistent_keyring_register;
 102 #endif
 103         struct work_struct      work;
 104 #ifdef CONFIG_SYSCTL
 105         struct ctl_table_set    set;
 106         struct ctl_table_header *sysctls;
 107 #endif
 108         struct ucounts          *ucounts;
 109         long ucount_max[UCOUNT_COUNTS];
 110         long rlimit_max[UCOUNT_RLIMIT_COUNTS];
 111
 112 #if IS_ENABLED(CONFIG_BINFMT_MISC)
 113         struct binfmt_misc *binfmt_misc;
 114 #endif
 115 } __randomize_layout;
 116
 117 struct ucounts {
 118         struct hlist_node node;
 119         struct user_namespace *ns;
 120         kuid_t uid;
 121         atomic_t count;
 122         atomic_long_t ucount[UCOUNT_COUNTS];
 123         atomic_long_t rlimit[UCOUNT_RLIMIT_COUNTS];
 124 };
 125
 126 extern struct user_namespace init_user_ns;
 127 extern struct ucounts init_ucounts;
 128
 129 bool setup_userns_sysctls(struct user_namespace *ns);
 130 void retire_userns_sysctls(struct user_namespace *ns);
 131 struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid, enum ucount_type type);
 132 void dec_ucount(struct ucounts *ucounts, enum ucount_type type);
 133 struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid);
 134 struct ucounts * __must_check get_ucounts(struct ucounts *ucounts);
 135 void put_ucounts(struct ucounts *ucounts);
 136
 137 static inline long get_rlimit_value(struct ucounts *ucounts, enum rlimit_type type)
 138 {
 139         return atomic_long_read(&ucounts->rlimit[type]);
 140 }
 141
 142 long inc_rlimit_ucounts(struct ucounts *ucounts, enum rlimit_type type, long v);
 143 bool dec_rlimit_ucounts(struct ucounts *ucounts, enum rlimit_type type, long v);
 144 long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum rlimit_type type,
 145                             bool override_rlimit);
 146 void dec_rlimit_put_ucounts(struct ucounts *ucounts, enum rlimit_type type);
 147 bool is_rlimit_overlimit(struct ucounts *ucounts, enum rlimit_type type, unsigned long max);
 148
 149 static inline long get_userns_rlimit_max(struct user_namespace *ns, enum rlimit_type type)
 150 {
 151         return READ_ONCE(ns->rlimit_max[type]);
 152 }
 153
 154 static inline void set_userns_rlimit_max(struct user_namespace *ns,
 155                 enum rlimit_type type, unsigned long max)
 156 {
 157         ns->rlimit_max[type] = max <= LONG_MAX ? max : LONG_MAX;
 158 }
 159
 160 #ifdef CONFIG_USER_NS
 161
 162 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
 163 {
 164         if (ns)
 165                 refcount_inc(&ns->ns.count);
 166         return ns;
 167 }
 168
 169 extern int create_user_ns(struct cred *new);
 170 extern int unshare_userns(unsigned long unshare_flags, struct cred **new_cred);
 171 extern void __put_user_ns(struct user_namespace *ns);
 172
 173 static inline void put_user_ns(struct user_namespace *ns)
 174 {
 175         if (ns && refcount_dec_and_test(&ns->ns.count))
 176                 __put_user_ns(ns);
 177 }
 178
 179 struct seq_operations;
 180 extern const struct seq_operations proc_uid_seq_operations;
 181 extern const struct seq_operations proc_gid_seq_operations;
 182 extern const struct seq_operations proc_projid_seq_operations;
 183 extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *);
 184 extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *);
 185 extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *);
 186 extern ssize_t proc_setgroups_write(struct file *, const char __user *, size_t, loff_t *);
 187 extern int proc_setgroups_show(struct seq_file *m, void *v);
 188 extern bool userns_may_setgroups(const struct user_namespace *ns);
 189 extern bool in_userns(const struct user_namespace *ancestor,
 190                        const struct user_namespace *child);
 191 extern bool current_in_userns(const struct user_namespace *target_ns);
 192 struct ns_common *ns_get_owner(struct ns_common *ns);
 193 #else
 194
 195 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
 196 {
 197         return &init_user_ns;
 198 }
 199
 200 static inline int create_user_ns(struct cred *new)
 201 {
 202         return -EINVAL;
 203 }
 204
 205 static inline int unshare_userns(unsigned long unshare_flags,
 206                                  struct cred **new_cred)
 207 {
 208         if (unshare_flags & CLONE_NEWUSER)
 209                 return -EINVAL;
 210         return 0;
 211 }
 212
 213 static inline void put_user_ns(struct user_namespace *ns)
 214 {
 215 }
 216
 217 static inline bool userns_may_setgroups(const struct user_namespace *ns)
 218 {
 219         return true;
 220 }
 221
 222 static inline bool in_userns(const struct user_namespace *ancestor,
 223                              const struct user_namespace *child)
 224 {
 225         return true;
 226 }
 227
 228 static inline bool current_in_userns(const struct user_namespace *target_ns)
 229 {
 230         return true;
 231 }
 232
 233 static inline struct ns_common *ns_get_owner(struct ns_common *ns)
 234 {
 235         return ERR_PTR(-EPERM);
 236 }
 237 #endif
 238
 239 #endif /* _LINUX_USER_H */