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