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