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