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