1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  *
4  * Definitions for mount interface. This describes the in the kernel build
5  * linkedlist with mounted filesystems.
6  *
7  * Author:  Marco van Wieringen <mvw@planets.elm.net>
8  *
9  */
10 #ifndef _LINUX_MOUNT_H
11 #define _LINUX_MOUNT_H
12 
13 #include <linux/types.h>
14 #include <asm/barrier.h>
15 
16 struct super_block;
17 struct dentry;
18 struct user_namespace;
19 struct file_system_type;
20 struct fs_context;
21 struct file;
22 struct path;
23 
24 #define MNT_NOSUID	0x01
25 #define MNT_NODEV	0x02
26 #define MNT_NOEXEC	0x04
27 #define MNT_NOATIME	0x08
28 #define MNT_NODIRATIME	0x10
29 #define MNT_RELATIME	0x20
30 #define MNT_READONLY	0x40	/* does the user want this to be r/o? */
31 #define MNT_NOSYMFOLLOW	0x80
32 
33 #define MNT_SHRINKABLE	0x100
34 #define MNT_WRITE_HOLD	0x200
35 
36 #define MNT_SHARED	0x1000	/* if the vfsmount is a shared mount */
37 #define MNT_UNBINDABLE	0x2000	/* if the vfsmount is a unbindable mount */
38 /*
39  * MNT_SHARED_MASK is the set of flags that should be cleared when a
40  * mount becomes shared.  Currently, this is only the flag that says a
41  * mount cannot be bind mounted, since this is how we create a mount
42  * that shares events with another mount.  If you add a new MNT_*
43  * flag, consider how it interacts with shared mounts.
44  */
45 #define MNT_SHARED_MASK	(MNT_UNBINDABLE)
46 #define MNT_USER_SETTABLE_MASK  (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \
47 				 | MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \
48 				 | MNT_READONLY | MNT_NOSYMFOLLOW)
49 #define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )
50 
51 #define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
52 			    MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED | \
53 			    MNT_CURSOR)
54 
55 #define MNT_INTERNAL	0x4000
56 
57 #define MNT_LOCK_ATIME		0x040000
58 #define MNT_LOCK_NOEXEC		0x080000
59 #define MNT_LOCK_NOSUID		0x100000
60 #define MNT_LOCK_NODEV		0x200000
61 #define MNT_LOCK_READONLY	0x400000
62 #define MNT_LOCKED		0x800000
63 #define MNT_DOOMED		0x1000000
64 #define MNT_SYNC_UMOUNT		0x2000000
65 #define MNT_MARKED		0x4000000
66 #define MNT_UMOUNT		0x8000000
67 #define MNT_CURSOR		0x10000000
68 
69 struct vfsmount {
70 	struct dentry *mnt_root;	/* root of the mounted tree */
71 	struct super_block *mnt_sb;	/* pointer to superblock */
72 	int mnt_flags;
73 	struct user_namespace *mnt_userns;
74 } __randomize_layout;
75 
mnt_user_ns(const struct vfsmount * mnt)76 static inline struct user_namespace *mnt_user_ns(const struct vfsmount *mnt)
77 {
78 	/* Pairs with smp_store_release() in do_idmap_mount(). */
79 	return smp_load_acquire(&mnt->mnt_userns);
80 }
81 
82 extern int mnt_want_write(struct vfsmount *mnt);
83 extern int mnt_want_write_file(struct file *file);
84 extern void mnt_drop_write(struct vfsmount *mnt);
85 extern void mnt_drop_write_file(struct file *file);
86 extern void mntput(struct vfsmount *mnt);
87 extern struct vfsmount *mntget(struct vfsmount *mnt);
88 extern struct vfsmount *mnt_clone_internal(const struct path *path);
89 extern bool __mnt_is_readonly(struct vfsmount *mnt);
90 extern bool mnt_may_suid(struct vfsmount *mnt);
91 
92 extern struct vfsmount *clone_private_mount(const struct path *path);
93 extern int __mnt_want_write(struct vfsmount *);
94 extern void __mnt_drop_write(struct vfsmount *);
95 
96 extern struct vfsmount *fc_mount(struct fs_context *fc);
97 extern struct vfsmount *vfs_create_mount(struct fs_context *fc);
98 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
99 				      int flags, const char *name,
100 				      void *data);
101 extern struct vfsmount *vfs_submount(const struct dentry *mountpoint,
102 				     struct file_system_type *type,
103 				     const char *name, void *data);
104 
105 extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
106 extern void mark_mounts_for_expiry(struct list_head *mounts);
107 
108 extern dev_t name_to_dev_t(const char *name);
109 extern bool path_is_mountpoint(const struct path *path);
110 
111 extern bool our_mnt(struct vfsmount *mnt);
112 
113 extern struct vfsmount *kern_mount(struct file_system_type *);
114 extern void kern_unmount(struct vfsmount *mnt);
115 extern int may_umount_tree(struct vfsmount *);
116 extern int may_umount(struct vfsmount *);
117 extern long do_mount(const char *, const char __user *,
118 		     const char *, unsigned long, void *);
119 extern struct vfsmount *collect_mounts(const struct path *);
120 extern void drop_collected_mounts(struct vfsmount *);
121 extern int iterate_mounts(int (*)(struct vfsmount *, void *), void *,
122 			  struct vfsmount *);
123 extern void kern_unmount_array(struct vfsmount *mnt[], unsigned int num);
124 
125 #endif /* _LINUX_MOUNT_H */
126