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 struct mnt_namespace {
9 atomic_t count;
10 struct ns_common ns;
11 struct mount * root;
12 /*
13 * Traversal and modification of .list is protected by either
14 * - taking namespace_sem for write, OR
15 * - taking namespace_sem for read AND taking .ns_lock.
16 */
17 struct list_head list;
18 spinlock_t ns_lock;
19 struct user_namespace *user_ns;
20 struct ucounts *ucounts;
21 u64 seq; /* Sequence number to prevent loops */
22 wait_queue_head_t poll;
23 u64 event;
24 unsigned int mounts; /* # of mounts in the namespace */
25 unsigned int pending_mounts;
26 } __randomize_layout;
27
28 struct mnt_pcp {
29 int mnt_count;
30 int mnt_writers;
31 };
32
33 struct mountpoint {
34 struct hlist_node m_hash;
35 struct dentry *m_dentry;
36 struct hlist_head m_list;
37 int m_count;
38 };
39
40 struct mount {
41 struct hlist_node mnt_hash;
42 struct mount *mnt_parent;
43 struct dentry *mnt_mountpoint;
44 struct vfsmount mnt;
45 union {
46 struct rcu_head mnt_rcu;
47 struct llist_node mnt_llist;
48 };
49 #ifdef CONFIG_SMP
50 struct mnt_pcp __percpu *mnt_pcp;
51 #else
52 int mnt_count;
53 int mnt_writers;
54 #endif
55 struct list_head mnt_mounts; /* list of children, anchored here */
56 struct list_head mnt_child; /* and going through their mnt_child */
57 struct list_head mnt_instance; /* mount instance on sb->s_mounts */
58 const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */
59 struct list_head mnt_list;
60 struct list_head mnt_expire; /* link in fs-specific expiry list */
61 struct list_head mnt_share; /* circular list of shared mounts */
62 struct list_head mnt_slave_list;/* list of slave mounts */
63 struct list_head mnt_slave; /* slave list entry */
64 struct mount *mnt_master; /* slave is on master->mnt_slave_list */
65 struct mnt_namespace *mnt_ns; /* containing namespace */
66 struct mountpoint *mnt_mp; /* where is it mounted */
67 union {
68 struct hlist_node mnt_mp_list; /* list mounts with the same mountpoint */
69 struct hlist_node mnt_umount;
70 };
71 struct list_head mnt_umounting; /* list entry for umount propagation */
72 #ifdef CONFIG_FSNOTIFY
73 struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
74 __u32 mnt_fsnotify_mask;
75 #endif
76 int mnt_id; /* mount identifier */
77 int mnt_group_id; /* peer group identifier */
78 int mnt_expiry_mark; /* true if marked for expiry */
79 struct hlist_head mnt_pins;
80 struct hlist_head mnt_stuck_children;
81 } __randomize_layout;
82
83 #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
84
real_mount(struct vfsmount * mnt)85 static inline struct mount *real_mount(struct vfsmount *mnt)
86 {
87 return container_of(mnt, struct mount, mnt);
88 }
89
mnt_has_parent(struct mount * mnt)90 static inline int mnt_has_parent(struct mount *mnt)
91 {
92 return mnt != mnt->mnt_parent;
93 }
94
is_mounted(struct vfsmount * mnt)95 static inline int is_mounted(struct vfsmount *mnt)
96 {
97 /* neither detached nor internal? */
98 return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
99 }
100
101 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
102
103 extern int __legitimize_mnt(struct vfsmount *, unsigned);
104 extern bool legitimize_mnt(struct vfsmount *, unsigned);
105
__path_is_mountpoint(const struct path * path)106 static inline bool __path_is_mountpoint(const struct path *path)
107 {
108 struct mount *m = __lookup_mnt(path->mnt, path->dentry);
109 return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
110 }
111
112 extern void __detach_mounts(struct dentry *dentry);
113
detach_mounts(struct dentry * dentry)114 static inline void detach_mounts(struct dentry *dentry)
115 {
116 if (!d_mountpoint(dentry))
117 return;
118 __detach_mounts(dentry);
119 }
120
get_mnt_ns(struct mnt_namespace * ns)121 static inline void get_mnt_ns(struct mnt_namespace *ns)
122 {
123 atomic_inc(&ns->count);
124 }
125
126 extern seqlock_t mount_lock;
127
lock_mount_hash(void)128 static inline void lock_mount_hash(void)
129 {
130 write_seqlock(&mount_lock);
131 }
132
unlock_mount_hash(void)133 static inline void unlock_mount_hash(void)
134 {
135 write_sequnlock(&mount_lock);
136 }
137
138 struct proc_mounts {
139 struct mnt_namespace *ns;
140 struct path root;
141 int (*show)(struct seq_file *, struct vfsmount *);
142 struct mount cursor;
143 };
144
145 extern const struct seq_operations mounts_op;
146
147 extern bool __is_local_mountpoint(struct dentry *dentry);
is_local_mountpoint(struct dentry * dentry)148 static inline bool is_local_mountpoint(struct dentry *dentry)
149 {
150 if (!d_mountpoint(dentry))
151 return false;
152
153 return __is_local_mountpoint(dentry);
154 }
155
is_anon_ns(struct mnt_namespace * ns)156 static inline bool is_anon_ns(struct mnt_namespace *ns)
157 {
158 return ns->seq == 0;
159 }
160
161 extern void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor);
162
