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 list_head notify_list; 9 10 struct mnt_namespace { 11 struct ns_common ns; 12 struct mount * root; 13 struct { 14 struct rb_root mounts; /* Protected by namespace_sem */ 15 struct rb_node *mnt_last_node; /* last (rightmost) mount in the rbtree */ 16 struct rb_node *mnt_first_node; /* first (leftmost) mount in the rbtree */ 17 }; 18 struct user_namespace *user_ns; 19 struct ucounts *ucounts; 20 wait_queue_head_t poll; 21 u64 seq_origin; /* Sequence number of origin mount namespace */ 22 u64 event; 23 #ifdef CONFIG_FSNOTIFY 24 __u32 n_fsnotify_mask; 25 struct fsnotify_mark_connector __rcu *n_fsnotify_marks; 26 #endif 27 unsigned int nr_mounts; /* # of mounts in the namespace */ 28 unsigned int pending_mounts; 29 refcount_t passive; /* number references not pinning @mounts */ 30 } __randomize_layout; 31 32 struct mnt_pcp { 33 int mnt_count; 34 int mnt_writers; 35 }; 36 37 struct mountpoint { 38 struct hlist_node m_hash; 39 struct dentry *m_dentry; 40 struct hlist_head m_list; 41 }; 42 43 struct mount { 44 struct hlist_node mnt_hash; 45 struct mount *mnt_parent; 46 struct dentry *mnt_mountpoint; 47 struct vfsmount mnt; 48 union { 49 struct rb_node mnt_node; /* node in the ns->mounts rbtree */ 50 struct rcu_head mnt_rcu; 51 struct llist_node mnt_llist; 52 }; 53 #ifdef CONFIG_SMP 54 struct mnt_pcp __percpu *mnt_pcp; 55 #else 56 int mnt_count; 57 int mnt_writers; 58 #endif 59 struct list_head mnt_mounts; /* list of children, anchored here */ 60 struct list_head mnt_child; /* and going through their mnt_child */ 61 struct mount *mnt_next_for_sb; /* the next two fields are hlist_node, */ 62 struct mount * __aligned(1) *mnt_pprev_for_sb; 63 /* except that LSB of pprev is stolen */ 64 #define WRITE_HOLD 1 /* ... for use by mnt_hold_writers() */ 65 const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */ 66 struct list_head mnt_list; 67 struct list_head mnt_expire; /* link in fs-specific expiry list */ 68 struct list_head mnt_share; /* circular list of shared mounts */ 69 struct hlist_head mnt_slave_list;/* list of slave mounts */ 70 struct hlist_node mnt_slave; /* slave list entry */ 71 struct mount *mnt_master; /* slave is on master->mnt_slave_list */ 72 struct mnt_namespace *mnt_ns; /* containing namespace */ 73 struct mountpoint *mnt_mp; /* where is it mounted */ 74 union { 75 struct hlist_node mnt_mp_list; /* list mounts with the same mountpoint */ 76 struct hlist_node mnt_umount; 77 }; 78 #ifdef CONFIG_FSNOTIFY 79 struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks; 80 __u32 mnt_fsnotify_mask; 81 struct list_head to_notify; /* need to queue notification */ 82 struct mnt_namespace *prev_ns; /* previous namespace (NULL if none) */ 83 #endif 84 int mnt_t_flags; /* namespace_sem-protected flags */ 85 int mnt_id; /* mount identifier, reused */ 86 u64 mnt_id_unique; /* mount ID unique until reboot */ 87 int mnt_group_id; /* peer group identifier */ 88 int mnt_expiry_mark; /* true if marked for expiry */ 89 struct hlist_head mnt_pins; 90 struct hlist_head mnt_stuck_children; 91 struct mount *overmount; /* mounted on ->mnt_root */ 92 } __randomize_layout; 93 94 enum { 95 T_SHARED = 1, /* mount is shared */ 96 T_UNBINDABLE = 2, /* mount is unbindable */ 97 T_MARKED = 4, /* internal mark for propagate_... */ 98 T_UMOUNT_CANDIDATE = 8, /* for propagate_umount */ 99 100 /* 101 * T_SHARED_MASK is the set of flags that should be cleared when a 102 * mount becomes shared. Currently, this is only the flag that says a 103 * mount cannot be bind mounted, since this is how we create a mount 104 * that shares events with another mount. If you add a new T_* 105 * flag, consider how it interacts with shared mounts. 106 */ 107 T_SHARED_MASK = T_UNBINDABLE, 108 }; 109 110 #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */ 111 112 static inline struct mount *real_mount(struct vfsmount *mnt) 113 { 114 return container_of(mnt, struct mount, mnt); 115 } 116 117 static inline int mnt_has_parent(const struct mount *mnt) 118 { 119 return mnt != mnt->mnt_parent; 120 } 121 122 static inline int is_mounted(struct vfsmount *mnt) 123 { 124 /* neither detached nor internal? */ 125 return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns); 126 } 127 128 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *); 129 130 extern int __legitimize_mnt(struct vfsmount *, unsigned); 131 132 static inline bool __path_is_mountpoint(const struct path *path) 133 { 134 struct mount *m = __lookup_mnt(path->mnt, path->dentry); 135 return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT)); 136 } 137 138 extern void __detach_mounts(struct dentry *dentry); 139 140 static inline void detach_mounts(struct dentry *dentry) 141 { 142 if (!d_mountpoint(dentry)) 143 return; 144 __detach_mounts(dentry); 145 } 146 147 static inline void get_mnt_ns(struct mnt_namespace *ns) 148 { 149 ns_ref_inc(ns); 150 } 151 152 extern seqlock_t mount_lock; 153 154 DEFINE_LOCK_GUARD_0(mount_writer, write_seqlock(&mount_lock), 155 write_sequnlock(&mount_lock)) 156 DEFINE_LOCK_GUARD_0(mount_locked_reader, read_seqlock_excl(&mount_lock), 157 read_sequnlock_excl(&mount_lock)) 158 159 struct proc_mounts { 160 struct mnt_namespace *ns; 161 struct path root; 162 int (*show)(struct seq_file *, struct vfsmount *); 163 }; 164 165 extern const struct seq_operations mounts_op; 166 167 extern bool __is_local_mountpoint(const struct dentry *dentry); 168 static inline bool is_local_mountpoint(const struct dentry *dentry) 169 { 170 if (!d_mountpoint(dentry)) 171 return false; 172 173 return __is_local_mountpoint(dentry); 174 } 175 176 static inline bool is_anon_ns(struct mnt_namespace *ns) 177 { 178 return ns->ns.ns_id == 0; 179 } 180 181 static inline bool anon_ns_root(const struct mount *m) 182 { 183 struct mnt_namespace *ns = READ_ONCE(m->mnt_ns); 184 185 return !IS_ERR_OR_NULL(ns) && is_anon_ns(ns) && m == ns->root; 186 } 187 188 static inline bool mnt_ns_attached(const struct mount *mnt) 189 { 190 return !RB_EMPTY_NODE(&mnt->mnt_node); 191 } 192 193 static inline bool mnt_ns_empty(const struct mnt_namespace *ns) 194 { 195 return RB_EMPTY_ROOT(&ns->mounts); 196 } 197 198 static inline void move_from_ns(struct mount *mnt) 199 { 200 struct mnt_namespace *ns = mnt->mnt_ns; 201 WARN_ON(!mnt_ns_attached(mnt)); 202 if (ns->mnt_last_node == &mnt->mnt_node) 203 ns->mnt_last_node = rb_prev(&mnt->mnt_node); 204 if (ns->mnt_first_node == &mnt->mnt_node) 205 ns->mnt_first_node = rb_next(&mnt->mnt_node); 206 rb_erase(&mnt->mnt_node, &ns->mounts); 207 RB_CLEAR_NODE(&mnt->mnt_node); 208 } 209 210 bool has_locked_children(struct mount *mnt, struct dentry *dentry); 211 struct mnt_namespace *get_sequential_mnt_ns(struct mnt_namespace *mnt_ns, 212 bool previous); 213 214 static inline struct mnt_namespace *to_mnt_ns(struct ns_common *ns) 215 { 216 return container_of(ns, struct mnt_namespace, ns); 217 } 218 219 #ifdef CONFIG_FSNOTIFY 220 static inline void mnt_notify_add(struct mount *m) 221 { 222 /* Optimize the case where there are no watches */ 223 if ((m->mnt_ns && m->mnt_ns->n_fsnotify_marks) || 224 (m->prev_ns && m->prev_ns->n_fsnotify_marks)) 225 list_add_tail(&m->to_notify, ¬ify_list); 226 else 227 m->prev_ns = m->mnt_ns; 228 } 229 #else 230 static inline void mnt_notify_add(struct mount *m) 231 { 232 } 233 #endif 234 235 static inline struct mount *topmost_overmount(struct mount *m) 236 { 237 while (m->overmount) 238 m = m->overmount; 239 return m; 240 } 241 242 static inline bool __test_write_hold(struct mount * __aligned(1) *val) 243 { 244 return (unsigned long)val & WRITE_HOLD; 245 } 246 247 static inline bool test_write_hold(const struct mount *m) 248 { 249 return __test_write_hold(m->mnt_pprev_for_sb); 250 } 251 252 static inline void set_write_hold(struct mount *m) 253 { 254 m->mnt_pprev_for_sb = (void *)((unsigned long)m->mnt_pprev_for_sb 255 | WRITE_HOLD); 256 } 257 258 static inline void clear_write_hold(struct mount *m) 259 { 260 m->mnt_pprev_for_sb = (void *)((unsigned long)m->mnt_pprev_for_sb 261 & ~WRITE_HOLD); 262 } 263 264 struct mnt_namespace *mnt_ns_from_dentry(struct dentry *dentry); 265