30 #include <uapi/linux/mount.h>
37 /* Maximum number of mounts in a mount namespace */
105 static int mnt_alloc_id(struct mount *mnt)  in mnt_alloc_id()
115 static void mnt_free_id(struct mount *mnt)  in mnt_free_id()
123 static int mnt_alloc_group_id(struct mount *mnt)  in mnt_alloc_group_id()
136 void mnt_release_group_id(struct mount *mnt)  in mnt_release_group_id()
145 static inline void mnt_add_count(struct mount *mnt, int n)  in mnt_add_count()
159 int mnt_get_count(struct mount *mnt)  in mnt_get_count()
175 static struct mount *alloc_vfsmnt(const char *name)  in alloc_vfsmnt()
177 	struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);  in alloc_vfsmnt()
237  * __mnt_is_readonly: check whether a mount is read-only
238  * @mnt: the mount to check for its write status
253 static inline void mnt_inc_writers(struct mount *mnt)  in mnt_inc_writers()
262 static inline void mnt_dec_writers(struct mount *mnt)  in mnt_dec_writers()
271 static unsigned int mnt_get_writers(struct mount *mnt)  in mnt_get_writers()
303  * __mnt_want_write - get write access to a mount without freeze protection
304  * @m: the mount on which to take a write
314 	struct mount *mnt = real_mount(m);  in __mnt_want_write()
343  * mnt_want_write - get write access to a mount
344  * @m: the mount on which to take a write
347  * it, and makes sure that writes are allowed (mount is read-write, filesystem
364  * mnt_clone_write - get write access to a mount
365  * @mnt: the mount on which to take a write
388  * __mnt_want_write_file - get write access to a file's mount
389  * @file: the file who's mount on which to take a write
403  * mnt_want_write_file - get write access to a file's mount
404  * @file: the file who's mount on which to take a write
422  * __mnt_drop_write - give up write access to a mount
423  * @mnt: the mount on which to give up write access
437  * mnt_drop_write - give up write access to a mount
438  * @mnt: the mount on which to give up write access
463 static int mnt_make_readonly(struct mount *mnt)  in mnt_make_readonly()
505 static int __mnt_unmake_readonly(struct mount *mnt)  in __mnt_unmake_readonly()
515 	struct mount *mnt;  in sb_prepare_remount_readonly()
549 static void free_vfsmnt(struct mount *mnt)  in free_vfsmnt()
560 	free_vfsmnt(container_of(head, struct mount, mnt_rcu));  in delayed_free_vfsmnt()
566 	struct mount *mnt;  in __legitimize_mnt()
606  * find the first mount at @dentry on vfsmount @mnt.
609 struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)  in __lookup_mnt()
612 	struct mount *p;  in __lookup_mnt()
621  * lookup_mnt - Return the first child mount mounted at path
626  * mount /dev/sda1 /mnt
627  * mount /dev/sda2 /mnt
628  * mount /dev/sda3 /mnt
630  * Then lookup_mnt() on the base /mnt dentry in the root mount will
638 	struct mount *child_mnt;  in lookup_mnt()
662 static inline bool mnt_is_cursor(struct mount *mnt)  in mnt_is_cursor()
669  *                         current mount namespace.
674  * mounts in the current mount namespace and test to see if the dentry
678  * need to identify all mounts that may be in the current mount
679  * namespace not just a mount that happens to have some specified
680  * parent mount.
685 	struct mount *mnt;  in __is_local_mountpoint()
791 static inline int check_mnt(struct mount *mnt)  in check_mnt()
821 static struct mountpoint *unhash_mnt(struct mount *mnt)  in unhash_mnt()
837 static void umount_mnt(struct mount *mnt)  in umount_mnt()
845 void mnt_set_mountpoint(struct mount *mnt,  in mnt_set_mountpoint()
847 			struct mount *child_mnt)  in mnt_set_mountpoint()
857 static void __attach_mnt(struct mount *mnt, struct mount *parent)  in __attach_mnt()
867 static void attach_mnt(struct mount *mnt,  in attach_mnt()
868 			struct mount *parent,  in attach_mnt()
875 void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt)  in mnt_change_mountpoint()
878 	struct mount *old_parent = mnt->mnt_parent;  in mnt_change_mountpoint()
893 static void commit_tree(struct mount *mnt)  in commit_tree()
895 	struct mount *parent = mnt->mnt_parent;  in commit_tree()
896 	struct mount *m;  in commit_tree()
915 static struct mount *next_mnt(struct mount *p, struct mount *root)  in next_mnt()
928 	return list_entry(next, struct mount, mnt_child);  in next_mnt()
931 static struct mount *skip_mnt_tree(struct mount *p)  in skip_mnt_tree()
935 		p = list_entry(prev, struct mount, mnt_child);  in skip_mnt_tree()
942  * vfs_create_mount - Create a mount for a configured superblock
945  * Create a mount to an already configured superblock.  If necessary, the
948  * Note that this does not attach the mount to anything.
952 	struct mount *mnt;  in vfs_create_mount()
1023 	 * through from the parent mount to the submount don't support  in vfs_submount()
1033 static struct mount *clone_mnt(struct mount *old, struct dentry *root,  in clone_mnt()
1037 	struct mount *mnt;  in clone_mnt()
1084 	/* stick the duplicate mount on the same expiry list  in clone_mnt()
1099 static void cleanup_mnt(struct mount *mnt)  in cleanup_mnt()
1102 	struct mount *m;  in cleanup_mnt()
1126 	cleanup_mnt(container_of(head, struct mount, mnt_rcu));  in __cleanup_mnt()
1133 	struct mount *m, *t;  in delayed_mntput()
1140 static void mntput_no_expire(struct mount *mnt)  in mntput_no_expire()
1185 		struct mount *p, *tmp;  in mntput_no_expire()
1211 		struct mount *m = real_mount(mnt);  in mntput()
1228 /* path_is_mountpoint() - Check if path is a mount in the current
1259 	struct mount *p;  in mnt_clone_internal()
1268 static struct mount *mnt_list_next(struct mnt_namespace *ns,  in mnt_list_next()
1271 	struct mount *mnt, *ret = NULL;  in mnt_list_next()
1309 	struct mount *mnt = v;  in m_next()
1318 	struct mount *mnt = v;  in m_stop()
1332 	struct mount *r = v;  in m_show()
1343 void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor)  in mnt_cursor_del()
1354  * may_umount_tree - check if a mount tree is busy
1355  * @mnt: root of mount tree
1363 	struct mount *mnt = real_mount(m);  in may_umount_tree()
1366 	struct mount *p;  in may_umount_tree()
1386  * may_umount - check if a mount point is busy
1387  * @mnt: root of mount
1389  * This is called to check if a mount point has any
1391  * mount has sub mounts this will return busy
1416 	struct mount *m;  in namespace_unlock()
1448 static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how)  in disconnect_mount()
1454 	/* A mount without a parent has nothing to be connected to */  in disconnect_mount()
1465 	/* Has it been requested that the mount remain connected? */  in disconnect_mount()
1469 	/* Is the mount locked such that it needs to remain connected? */  in disconnect_mount()
1473 	/* By default disconnect the mount */  in disconnect_mount()
1481 static void umount_tree(struct mount *mnt, enum umount_tree_flags how)  in umount_tree()
1484 	struct mount *p;  in umount_tree()
1507 		p = list_first_entry(&tmp_list, struct mount, mnt_list);  in umount_tree()
1535 static void shrink_submounts(struct mount *mnt);
1560 static int do_umount(struct mount *mnt, int flags)  in do_umount()
1597 	 * mount, and they will themselves hold resources we must  in do_umount()
1601 	 * must return, and the like. Thats for the mount program to worry  in do_umount()
1660  * to an existing mountpoint, and wind up leaking the mount.
1669 	struct mount *mnt;  in __detach_mounts()
1679 		mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);  in __detach_mounts()
1704 		     "WARNING: the mand mount option is being deprecated and\n"  in may_mandlock()
1712 	pr_warn("VFS: \"mand\" mount option not supported");  in may_mandlock()
1719 	struct mount *mnt = real_mount(path->mnt);  in can_umount()
1737 	struct mount *mnt = real_mount(path->mnt);  in path_umount()
1787 	/* Is this a proxy for a mount namespace? */  in is_mnt_ns_file()
1804 	/* Could bind mounting the mount namespace inode cause a  in mnt_ns_loop()
1805 	 * mount namespace loop?  in mnt_ns_loop()
1815 struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,  in copy_tree()
1818 	struct mount *res, *p, *q, *r, *parent;  in copy_tree()
1834 		struct mount *s;  in copy_tree()
1884 	struct mount *tree;  in collect_mounts()
1927 static bool has_locked_children(struct mount *mnt, struct dentry *dentry)  in has_locked_children()
1929 	struct mount *child;  in has_locked_children()
1946  * to the originating mount won't be propagated into this).
1952 	struct mount *old_mnt = real_mount(path->mnt);  in clone_private_mount()
1953 	struct mount *new_mnt;  in clone_private_mount()
1971 	/* Longterm mount to be removed by kern_unmount*() */  in clone_private_mount()
1985 	struct mount *mnt;  in iterate_mounts()
1997 static void lock_mnt_tree(struct mount *mnt)  in lock_mnt_tree()
1999 	struct mount *p;  in lock_mnt_tree()
2003 		/* Don't allow unprivileged users to change mount flags */  in lock_mnt_tree()
2017 		/* Don't allow unprivileged users to reveal what is under a mount */  in lock_mnt_tree()
2024 static void cleanup_group_ids(struct mount *mnt, struct mount *end)  in cleanup_group_ids()
2026 	struct mount *p;  in cleanup_group_ids()
2034 static int invent_group_ids(struct mount *mnt, bool recurse)  in invent_group_ids()
2036 	struct mount *p;  in invent_group_ids()
2051 int count_mounts(struct mnt_namespace *ns, struct mount *mnt)  in count_mounts()
2055 	struct mount *p;  in count_mounts()
2074  *  @source_mnt : mount tree to be attached
2075  *  @nd         : place the mount tree @source_mnt is attached
2077  *  		   store the parent mount and mountpoint dentry.
2080  *  NOTE: in the table below explains the semantics when a source mount
2081  *  of a given type is attached to a destination mount of a given type.
2083  * |         BIND MOUNT OPERATION                                            |
2094  * A bind operation clones the source mount and mounts the clone on the
2095  * destination mount.
2097  * (++)  the cloned mount is propagated to all the mounts in the propagation
2098  * 	 tree of the destination mount and the cloned mount is added to
2099  * 	 the peer group of the source mount.
2100  * (+)   the cloned mount is created under the destination mount and is marked
2101  *       as shared. The cloned mount is added to the peer group of the source
2102  *       mount.
2103  * (+++) the mount is propagated to all the mounts in the propagation tree
2104  *       of the destination mount and the cloned mount is made slave
2105  *       of the same master as that of the source mount. The cloned mount
2107  * (*)   the cloned mount is made a slave of the same master as that of the
2108  * 	 source mount.
2111  * |         		MOVE MOUNT OPERATION                                 |
2123  * (+)  the mount is moved to the destination. And is then propagated to
2124  * 	all the mounts in the propagation tree of the destination mount.
2125  * (+*)  the mount is moved to the destination.
2126  * (+++)  the mount is moved to the destination and is then propagated to
2127  * 	all the mounts belonging to the destination mount's propagation tree.
2128  * 	the mount is marked as 'shared and slave'.
2129  * (*)	the mount continues to be a slave at the new location.
2131  * if the source mount is a tree, the operations explained above is
2132  * applied to each mount in the tree.
2136 static int attach_recursive_mnt(struct mount *source_mnt,  in attach_recursive_mnt()
2137 			struct mount *dest_mnt,  in attach_recursive_mnt()
2145 	struct mount *child, *p;  in attach_recursive_mnt()
2156 	/* Is there space to add these mounts to the mount namespace? */  in attach_recursive_mnt()
2190 		struct mount *q;  in attach_recursive_mnt()
2209 		child = hlist_entry(tree_list.first, struct mount, mnt_hash);  in attach_recursive_mnt()
2266 static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp)  in graft_tree()
2300 	struct mount *m;  in do_change_type()
2301 	struct mount *mnt = real_mount(path->mnt);  in do_change_type()
2330 static struct mount *__do_loopback(struct path *old_path, int recurse)  in __do_loopback()
2332 	struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt);  in __do_loopback()
2355  * do loopback mount.
2361 	struct mount *mnt = NULL, *parent;  in do_loopback()
2407 	struct mount *mnt, *p;  in open_detached_copy()
2494  * Don't allow locked mount flags to be cleared.
2499 static bool can_change_locked_flags(struct mount *mnt, unsigned int mnt_flags)  in can_change_locked_flags()
2526 static int change_mount_ro_state(struct mount *mnt, unsigned int mnt_flags)  in change_mount_ro_state()
2540  * Update the user-settable attributes on a mount.  The caller must hold
2543 static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags)  in set_mount_attributes()
2577  * to mount(2).
2582 	struct mount *mnt = real_mount(path->mnt);  in do_reconfigure_mnt()
2615 	struct mount *mnt = real_mount(path->mnt);  in do_remount()
2650 static inline int tree_contains_unbindable(struct mount *mnt)  in tree_contains_unbindable()
2652 	struct mount *p;  in tree_contains_unbindable()
2661  * Check that there aren't references to earlier/same mount namespaces in the
2662  * specified subtree.  Such references can act as pins for mount namespaces
2663  * that aren't checked by the mount-cycle checking code, thereby allowing
2666 static bool check_for_nsfs_mounts(struct mount *subtree)  in check_for_nsfs_mounts()
2668 	struct mount *p;  in check_for_nsfs_mounts()
2685 	struct mount *p;  in do_move_mount()
2686 	struct mount *old;  in do_move_mount()
2687 	struct mount *parent;  in do_move_mount()
2726 	 * Don't move a mount residing in a shared parent.  in do_move_mount()
2731 	 * Don't move a mount tree containing unbindable mounts to a destination  in do_move_mount()
2732 	 * mount which is shared.  in do_move_mount()
2748 	/* if the mount is moved, it should no longer be expire  in do_move_mount()
2782  * add a mount into a namespace's mount tree
2784 static int do_add_mount(struct mount *newmnt, struct mountpoint *mp,  in do_add_mount()
2787 	struct mount *parent = real_mount(path->mnt);  in do_add_mount()
2800 	/* Refuse the same filesystem on the same mount point */  in do_add_mount()
2815  * Create a new mount using a superblock configuration and request it
2856  * create a new mount for userspace and request it to be added into the
2912 	struct mount *mnt;  in finish_automount()
2921 	/* The new mount record should have at least 2 refs to prevent it being  in finish_automount()
2935 	 * got", not "try to mount it on top".  in finish_automount()
2979  * mnt_set_expiry - Put a mount on an expiration list
2980  * @mnt: The mount to list.
2981  * @expiry_list: The list to add the mount to.
3000 	struct mount *mnt, *next;  in mark_mounts_for_expiry()
3022 		mnt = list_first_entry(&graveyard, struct mount, mnt_expire);  in mark_mounts_for_expiry()
3038 static int select_submounts(struct mount *parent, struct list_head *graveyard)  in select_submounts()
3040 	struct mount *this_parent = parent;  in select_submounts()
3049 		struct mount *mnt = list_entry(tmp, struct mount, mnt_child);  in select_submounts()
3084 static void shrink_submounts(struct mount *mnt)  in shrink_submounts()
3087 	struct mount *m;  in shrink_submounts()
3092 			m = list_first_entry(&graveyard, struct mount,  in shrink_submounts()
3143  * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
3149  * Pre-0.97 versions of mount() didn't have a flags word.
3269  * mount a reference to an older mount namespace into the current
3270  * mount namespace, preventing reference counting loops.  A 64bit
3317 	struct mount *p, *q;  in copy_mnt_ns()
3318 	struct mount *old;  in copy_mnt_ns()
3319 	struct mount *new;  in copy_mnt_ns()
3393 	struct mount *mnt = real_mount(m);  in mount_subtree()
3428 SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,  in SYSCALL_DEFINE5()  argument
3463  * Create a kernel mount representation for a new, prepared superblock
3473 	struct mount *mnt;  in SYSCALL_DEFINE3()
3530 	/* There must be a valid superblock or we can't mount it */  in SYSCALL_DEFINE3()
3537 		pr_warn("VFS: Mount too revealing\n");  in SYSCALL_DEFINE3()
3557 	/* We've done the mount bit - now move the file context into more or  in SYSCALL_DEFINE3()
3603  * Move a mount from one place to another.  In combination with
3604  * fsopen()/fsmount() this is used to install a new mount and in combination
3606  * a mount subtree.
3665 bool is_path_reachable(struct mount *mnt, struct dentry *dentry,  in is_path_reachable()
3706  *    /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
3707  *    though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
3714 	struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent;  in SYSCALL_DEFINE2()
3783 	/* mount old root on put_old */  in SYSCALL_DEFINE2()
3785 	/* mount new_root on / */  in SYSCALL_DEFINE2()
3789 	/* A moved mount should not expire automatically */  in SYSCALL_DEFINE2()
3812 	struct mount *m;  in init_mount_tree()
3843 	mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount),  in mnt_init()
3846 	mount_hashtable = alloc_large_system_hash("Mount-cache",  in mnt_init()
3858 		panic("Failed to allocate mount hash table\n");  in mnt_init()
3888 		 * it is a longterm mount, don't release mnt until  in kern_mount()
3899 	/* release long term mount so mount point can be released */  in kern_unmount()
3955 	struct mount *mnt;  in mnt_already_visible()
3961 		struct mount *child;  in mnt_already_visible()
3970 		/* This mount is not fully visible if it's root directory  in mnt_already_visible()
3976 		/* A local view of the mount flags */  in mnt_already_visible()
3983 		/* Verify the mount flags are equal to or more permissive  in mnt_already_visible()
3984 		 * than the proposed new mount.  in mnt_already_visible()
3993 		/* This mount is not fully visible if there are any  in mnt_already_visible()