1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #include <linux/mount.h> 3 #include <linux/seq_file.h> 4 #include <linux/poll.h> 5 #include <linux/ns_common.h> 6 #include <linux/fs_pin.h> 7 8 extern struct file_system_type nullfs_fs_type; 9 extern struct dentry *nullfs_new_file(struct super_block *sb); 10 extern struct vfsmount *knullfs; 11 extern struct list_head notify_list; 12 13 struct mnt_namespace { 14 struct ns_common ns; 15 struct mount * root; 16 struct { 17 struct rb_root mounts; /* Protected by namespace_sem */ 18 struct rb_node *mnt_last_node; /* last (rightmost) mount in the rbtree */ 19 struct rb_node *mnt_first_node; /* first (leftmost) mount in the rbtree */ 20 }; 21 struct user_namespace *user_ns; 22 struct ucounts *ucounts; 23 wait_queue_head_t poll; 24 u64 seq_origin; /* Sequence number of origin mount namespace */ 25 u64 event; 26 #ifdef CONFIG_FSNOTIFY 27 __u32 n_fsnotify_mask; 28 struct fsnotify_mark_connector __rcu *n_fsnotify_marks; 29 #endif 30 struct hlist_head mnt_visible_mounts; /* SB_I_USERNS_VISIBLE mounts */ 31 unsigned int nr_mounts; /* # of mounts in the namespace */ 32 unsigned int pending_mounts; 33 refcount_t passive; /* number references not pinning @mounts */ 34 bool is_anon; 35 } __randomize_layout; 36 37 struct mnt_pcp { 38 unsigned int mnt_gets; 39 unsigned int mnt_puts; 40 int mnt_writers; 41 }; 42 43 struct mountpoint { 44 struct hlist_node m_hash; 45 struct dentry *m_dentry; 46 struct hlist_head m_list; /* mounts on it and pins */ 47 struct hlist_head m_covers; /* covers of unmounted parents */ 48 }; 49 50 struct mnt_cover; 51 52 struct mount { 53 struct hlist_node mnt_hash; 54 struct mount *mnt_parent; 55 struct dentry *mnt_mountpoint; 56 struct vfsmount mnt; 57 union { 58 struct rb_node mnt_node; /* node in the ns->mounts rbtree */ 59 struct rcu_head mnt_rcu; 60 struct llist_node mnt_llist; 61 }; 62 #ifdef CONFIG_SMP 63 struct mnt_pcp __percpu *mnt_pcp; 64 #else 65 int mnt_count; 66 int mnt_writers; 67 #endif 68 struct list_head mnt_mounts; /* list of children, anchored here */ 69 struct list_head mnt_child; /* and going through their mnt_child */ 70 struct mount *mnt_next_for_sb; /* the next two fields are hlist_node, */ 71 struct mount * __aligned(1) *mnt_pprev_for_sb; 72 /* except that LSB of pprev is stolen */ 73 #define WRITE_HOLD 1 /* ... for use by mnt_hold_writers() */ 74 const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */ 75 struct list_head mnt_list; 76 struct list_head mnt_expire; /* link in fs-specific expiry list */ 77 struct list_head mnt_share; /* circular list of shared mounts */ 78 struct hlist_head mnt_slave_list;/* list of slave mounts */ 79 struct hlist_node mnt_slave; /* slave list entry */ 80 struct mount *mnt_master; /* slave is on master->mnt_slave_list */ 81 /* 82 * Containing namespace (active or deactivating, non-refcounted). 83 * Normally protected by namespace_sem. 84 * Can also be accessed locklessly under RCU. RCU readers can't rely on 85 * the namespace still being active, but implicitly hold a passive 86 * reference (because an RCU delay happens between a namespace being 87 * deactivated and the corresponding passive refcount drop). 88 */ 89 struct mnt_namespace *mnt_ns; 90 struct mountpoint *mnt_mp; /* where is it mounted */ 91 union { 92 struct hlist_node mnt_mp_list; /* list mounts with the same mountpoint */ 93 struct hlist_node mnt_umount; /* on the unmounted list */ 94 }; 95 #ifdef CONFIG_FSNOTIFY 96 struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks; 97 __u32 mnt_fsnotify_mask; 98 struct list_head to_notify; /* need to queue notification */ 99 struct mnt_namespace *prev_ns; /* previous namespace (NULL if none) */ 100 #endif 101 int mnt_t_flags; /* namespace_sem-protected flags */ 102 int mnt_id; /* mount identifier, reused */ 103 u64 mnt_id_unique; /* mount ID unique until reboot */ 104 int mnt_group_id; /* peer group identifier */ 105 int mnt_expiry_mark; /* true if marked for expiry */ 106 struct hlist_head mnt_pins; 107 struct mnt_cover *mnt_cover; /* the one it may leave behind */ 108 struct hlist_head mnt_covers; /* left behind by its unmounted children */ 109 struct hlist_node mnt_ns_visible; /* link in ns->mnt_visible_mounts */ 110 struct mount *overmount; /* mounted on ->mnt_root */ 111 } __randomize_layout; 112 113 enum { 114 T_SHARED = 1, /* mount is shared */ 115 T_UNBINDABLE = 2, /* mount is unbindable */ 116 T_MARKED = 4, /* internal mark for propagate_... */ 117 T_UMOUNT_CANDIDATE = 8, /* for propagate_umount */ 118 119 /* 120 * T_SHARED_MASK is the set of flags that should be cleared when a 121 * mount becomes shared. Currently, this is only the flag that says a 122 * mount cannot be bind mounted, since this is how we create a mount 123 * that shares events with another mount. If you add a new T_* 124 * flag, consider how it interacts with shared mounts. 125 */ 126 T_SHARED_MASK = T_UNBINDABLE, 127 }; 128 129 #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */ 130 131 static inline struct mount *real_mount(struct vfsmount *mnt) 132 { 133 return container_of(mnt, struct mount, mnt); 134 } 135 136 static inline int mnt_has_parent(const struct mount *mnt) 137 { 138 return mnt != mnt->mnt_parent; 139 } 140 141 static inline int is_mounted(struct vfsmount *mnt) 142 { 143 /* neither detached nor internal? */ 144 return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns); 145 } 146 147 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *); 148 149 extern int __legitimize_mnt(struct vfsmount *, unsigned); 150 151 static inline bool __path_is_mountpoint(const struct path *path) 152 { 153 struct mount *m = __lookup_mnt(path->mnt, path->dentry); 154 return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT)); 155 } 156 157 extern void __detach_mounts(struct dentry *dentry); 158 159 static inline void detach_mounts(struct dentry *dentry) 160 { 161 if (!d_mountpoint(dentry)) 162 return; 163 __detach_mounts(dentry); 164 } 165 166 static inline void get_mnt_ns(struct mnt_namespace *ns) 167 { 168 ns_ref_inc(ns); 169 } 170 171 extern seqlock_t mount_lock; 172 173 DEFINE_LOCK_GUARD_0(mount_writer, write_seqlock(&mount_lock), 174 write_sequnlock(&mount_lock)) 175 DEFINE_LOCK_GUARD_0(mount_locked_reader, read_seqlock_excl(&mount_lock), 176 read_sequnlock_excl(&mount_lock)) 177 178 struct proc_mounts { 179 struct mnt_namespace *ns; 180 struct path root; 181 int (*show)(struct seq_file *, struct vfsmount *); 182 }; 183 184 extern const struct seq_operations mounts_op; 185 186 extern bool __is_local_mountpoint(const struct dentry *dentry); 187 static inline bool is_local_mountpoint(const struct dentry *dentry) 188 { 189 if (!d_mountpoint(dentry)) 190 return false; 191 192 return __is_local_mountpoint(dentry); 193 } 194 195 static inline bool is_anon_ns(struct mnt_namespace *ns) 196 { 197 return ns->is_anon; 198 } 199 200 static inline bool anon_ns_root(const struct mount *m) 201 { 202 struct mnt_namespace *ns = READ_ONCE(m->mnt_ns); 203 204 return !IS_ERR_OR_NULL(ns) && is_anon_ns(ns) && m == ns->root; 205 } 206 207 static inline bool mnt_ns_attached(const struct mount *mnt) 208 { 209 return !RB_EMPTY_NODE(&mnt->mnt_node); 210 } 211 212 static inline bool mnt_ns_empty(const struct mnt_namespace *ns) 213 { 214 return RB_EMPTY_ROOT(&ns->mounts); 215 } 216 217 static inline void move_from_ns(struct mount *mnt) 218 { 219 struct mnt_namespace *ns = mnt->mnt_ns; 220 WARN_ON(!mnt_ns_attached(mnt)); 221 if (ns->mnt_last_node == &mnt->mnt_node) 222 ns->mnt_last_node = rb_prev(&mnt->mnt_node); 223 if (ns->mnt_first_node == &mnt->mnt_node) 224 ns->mnt_first_node = rb_next(&mnt->mnt_node); 225 rb_erase(&mnt->mnt_node, &ns->mounts); 226 RB_CLEAR_NODE(&mnt->mnt_node); 227 if (!hlist_unhashed(&mnt->mnt_ns_visible)) 228 hlist_del_init(&mnt->mnt_ns_visible); 229 } 230 231 bool has_locked_children(struct mount *mnt, struct dentry *dentry); 232 struct mnt_namespace *get_sequential_mnt_ns(struct mnt_namespace *mnt_ns, 233 bool previous); 234 235 static inline struct mnt_namespace *to_mnt_ns(struct ns_common *ns) 236 { 237 return container_of(ns, struct mnt_namespace, ns); 238 } 239 240 #ifdef CONFIG_FSNOTIFY 241 static inline void mnt_notify_add(struct mount *m) 242 { 243 /* queued already under this namespace_sem hold */ 244 if (!list_empty(&m->to_notify)) 245 return; 246 /* Optimize the case where there are no watches */ 247 if ((m->mnt_ns && m->mnt_ns->n_fsnotify_marks) || 248 (m->prev_ns && m->prev_ns->n_fsnotify_marks)) 249 list_add_tail(&m->to_notify, ¬ify_list); 250 else 251 m->prev_ns = m->mnt_ns; 252 } 253 #else 254 static inline void mnt_notify_add(struct mount *m) 255 { 256 } 257 #endif 258 259 static inline struct mount *topmost_overmount(struct mount *m) 260 { 261 while (m->overmount) 262 m = m->overmount; 263 return m; 264 } 265 266 static inline bool __test_write_hold(struct mount * __aligned(1) *val) 267 { 268 return (unsigned long)val & WRITE_HOLD; 269 } 270 271 static inline bool test_write_hold(const struct mount *m) 272 { 273 return __test_write_hold(m->mnt_pprev_for_sb); 274 } 275 276 static inline void set_write_hold(struct mount *m) 277 { 278 m->mnt_pprev_for_sb = (void *)((unsigned long)m->mnt_pprev_for_sb 279 | WRITE_HOLD); 280 } 281 282 static inline void clear_write_hold(struct mount *m) 283 { 284 m->mnt_pprev_for_sb = (void *)((unsigned long)m->mnt_pprev_for_sb 285 & ~WRITE_HOLD); 286 } 287 288 struct mnt_namespace *mnt_ns_from_dentry(struct dentry *dentry); 289