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
real_mount(struct vfsmount * mnt)115 static inline struct mount *real_mount(struct vfsmount *mnt)
116 {
117 return container_of(mnt, struct mount, mnt);
118 }
119
mnt_has_parent(const struct mount * mnt)120 static inline int mnt_has_parent(const struct mount *mnt)
121 {
122 return mnt != mnt->mnt_parent;
123 }
124
is_mounted(struct vfsmount * mnt)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
__path_is_mountpoint(const struct path * path)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
detach_mounts(struct dentry * dentry)143 static inline void detach_mounts(struct dentry *dentry)
144 {
145 if (!d_mountpoint(dentry))
146 return;
147 __detach_mounts(dentry);
148 }
149
get_mnt_ns(struct mnt_namespace * ns)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);
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
is_anon_ns(struct mnt_namespace * ns)174 static inline bool is_anon_ns(struct mnt_namespace *ns)
175 {
176 return ns->seq == 0;
177 }
178
anon_ns_root(const struct mount * m)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
mnt_ns_attached(const struct mount * mnt)186 static inline bool mnt_ns_attached(const struct mount *mnt)
187 {
188 return !RB_EMPTY_NODE(&mnt->mnt_node);
189 }
190
mnt_ns_empty(const struct mnt_namespace * ns)191 static inline bool mnt_ns_empty(const struct mnt_namespace *ns)
192 {
193 return RB_EMPTY_ROOT(&ns->mounts);
194 }
195
move_from_ns(struct mount * mnt)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
to_mnt_ns(struct ns_common * ns)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
mnt_notify_add(struct mount * m)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
mnt_notify_add(struct mount * m)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