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 struct mnt_namespace *mnt_ns; /* containing namespace */ 75 struct mountpoint *mnt_mp; /* where is it mounted */ 76 union { 77 struct hlist_node mnt_mp_list; /* list mounts with the same mountpoint */ 78 struct hlist_node mnt_umount; 79 }; 80 #ifdef CONFIG_FSNOTIFY 81 struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks; 82 __u32 mnt_fsnotify_mask; 83 struct list_head to_notify; /* need to queue notification */ 84 struct mnt_namespace *prev_ns; /* previous namespace (NULL if none) */ 85 #endif 86 int mnt_t_flags; /* namespace_sem-protected flags */ 87 int mnt_id; /* mount identifier, reused */ 88 u64 mnt_id_unique; /* mount ID unique until reboot */ 89 int mnt_group_id; /* peer group identifier */ 90 int mnt_expiry_mark; /* true if marked for expiry */ 91 struct hlist_head mnt_pins; 92 struct hlist_head mnt_stuck_children; 93 struct mount *overmount; /* mounted on ->mnt_root */ 94 } __randomize_layout; 95 96 enum { 97 T_SHARED = 1, /* mount is shared */ 98 T_UNBINDABLE = 2, /* mount is unbindable */ 99 T_MARKED = 4, /* internal mark for propagate_... */ 100 T_UMOUNT_CANDIDATE = 8, /* for propagate_umount */ 101 102 /* 103 * T_SHARED_MASK is the set of flags that should be cleared when a 104 * mount becomes shared. Currently, this is only the flag that says a 105 * mount cannot be bind mounted, since this is how we create a mount 106 * that shares events with another mount. If you add a new T_* 107 * flag, consider how it interacts with shared mounts. 108 */ 109 T_SHARED_MASK = T_UNBINDABLE, 110 }; 111 112 #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */ 113 114 static inline struct mount *real_mount(struct vfsmount *mnt) 115 { 116 return container_of(mnt, struct mount, mnt); 117 } 118 119 static inline int mnt_has_parent(const struct mount *mnt) 120 { 121 return mnt != mnt->mnt_parent; 122 } 123 124 static inline int is_mounted(struct vfsmount *mnt) 125 { 126 /* neither detached nor internal? */ 127 return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns); 128 } 129 130 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *); 131 132 extern int __legitimize_mnt(struct vfsmount *, unsigned); 133 134 static inline bool __path_is_mountpoint(const struct path *path) 135 { 136 struct mount *m = __lookup_mnt(path->mnt, path->dentry); 137 return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT)); 138 } 139 140 extern void __detach_mounts(struct dentry *dentry); 141 142 static inline void detach_mounts(struct dentry *dentry) 143 { 144 if (!d_mountpoint(dentry)) 145 return; 146 __detach_mounts(dentry); 147 } 148 149 static inline void get_mnt_ns(struct mnt_namespace *ns) 150 { 151 ns_ref_inc(ns); 152 } 153 154 extern seqlock_t mount_lock; 155 156 DEFINE_LOCK_GUARD_0(mount_writer, write_seqlock(&mount_lock), 157 write_sequnlock(&mount_lock)) 158 DEFINE_LOCK_GUARD_0(mount_locked_reader, read_seqlock_excl(&mount_lock), 159 read_sequnlock_excl(&mount_lock)) 160 161 struct proc_mounts { 162 struct mnt_namespace *ns; 163 struct path root; 164 int (*show)(struct seq_file *, struct vfsmount *); 165 }; 166 167 extern const struct seq_operations mounts_op; 168 169 extern bool __is_local_mountpoint(const struct dentry *dentry); 170 static inline bool is_local_mountpoint(const struct dentry *dentry) 171 { 172 if (!d_mountpoint(dentry)) 173 return false; 174 175 return __is_local_mountpoint(dentry); 176 } 177 178 static inline bool is_anon_ns(struct mnt_namespace *ns) 179 { 180 return ns->is_anon; 181 } 182 183 static inline bool anon_ns_root(const struct mount *m) 184 { 185 struct mnt_namespace *ns = READ_ONCE(m->mnt_ns); 186 187 return !IS_ERR_OR_NULL(ns) && is_anon_ns(ns) && m == ns->root; 188 } 189 190 static inline bool mnt_ns_attached(const struct mount *mnt) 191 { 192 return !RB_EMPTY_NODE(&mnt->mnt_node); 193 } 194 195 static inline bool mnt_ns_empty(const struct mnt_namespace *ns) 196 { 197 return RB_EMPTY_ROOT(&ns->mounts); 198 } 199 200 static inline void move_from_ns(struct mount *mnt) 201 { 202 struct mnt_namespace *ns = mnt->mnt_ns; 203 WARN_ON(!mnt_ns_attached(mnt)); 204 if (ns->mnt_last_node == &mnt->mnt_node) 205 ns->mnt_last_node = rb_prev(&mnt->mnt_node); 206 if (ns->mnt_first_node == &mnt->mnt_node) 207 ns->mnt_first_node = rb_next(&mnt->mnt_node); 208 rb_erase(&mnt->mnt_node, &ns->mounts); 209 RB_CLEAR_NODE(&mnt->mnt_node); 210 } 211 212 bool has_locked_children(struct mount *mnt, struct dentry *dentry); 213 struct mnt_namespace *get_sequential_mnt_ns(struct mnt_namespace *mnt_ns, 214 bool previous); 215 216 static inline struct mnt_namespace *to_mnt_ns(struct ns_common *ns) 217 { 218 return container_of(ns, struct mnt_namespace, ns); 219 } 220 221 #ifdef CONFIG_FSNOTIFY 222 static inline void mnt_notify_add(struct mount *m) 223 { 224 /* Optimize the case where there are no watches */ 225 if ((m->mnt_ns && m->mnt_ns->n_fsnotify_marks) || 226 (m->prev_ns && m->prev_ns->n_fsnotify_marks)) 227 list_add_tail(&m->to_notify, ¬ify_list); 228 else 229 m->prev_ns = m->mnt_ns; 230 } 231 #else 232 static inline void mnt_notify_add(struct mount *m) 233 { 234 } 235 #endif 236 237 static inline struct mount *topmost_overmount(struct mount *m) 238 { 239 while (m->overmount) 240 m = m->overmount; 241 return m; 242 } 243 244 static inline bool __test_write_hold(struct mount * __aligned(1) *val) 245 { 246 return (unsigned long)val & WRITE_HOLD; 247 } 248 249 static inline bool test_write_hold(const struct mount *m) 250 { 251 return __test_write_hold(m->mnt_pprev_for_sb); 252 } 253 254 static inline void set_write_hold(struct mount *m) 255 { 256 m->mnt_pprev_for_sb = (void *)((unsigned long)m->mnt_pprev_for_sb 257 | WRITE_HOLD); 258 } 259 260 static inline void clear_write_hold(struct mount *m) 261 { 262 m->mnt_pprev_for_sb = (void *)((unsigned long)m->mnt_pprev_for_sb 263 & ~WRITE_HOLD); 264 } 265 266 struct mnt_namespace *mnt_ns_from_dentry(struct dentry *dentry); 267