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