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