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 unsigned 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()
236  * __mnt_is_readonly: check whether a mount is read-only
237  * @mnt: the mount to check for its write status
252 static inline void mnt_inc_writers(struct mount *mnt)  in mnt_inc_writers()
261 static inline void mnt_dec_writers(struct mount *mnt)  in mnt_dec_writers()
270 static unsigned int mnt_get_writers(struct mount *mnt)  in mnt_get_writers()
302  * __mnt_want_write - get write access to a mount without freeze protection
303  * @m: the mount on which to take a write
313 	struct mount *mnt = real_mount(m);  in __mnt_want_write()
342  * mnt_want_write - get write access to a mount
343  * @m: the mount on which to take a write
346  * it, and makes sure that writes are allowed (mount is read-write, filesystem
363  * mnt_clone_write - get write access to a mount
364  * @mnt: the mount on which to take a write
387  * __mnt_want_write_file - get write access to a file's mount
388  * @file: the file who's mount on which to take a write
402  * mnt_want_write_file - get write access to a file's mount
403  * @file: the file who's mount on which to take a write
421  * __mnt_drop_write - give up write access to a mount
422  * @mnt: the mount on which to give up write access
436  * mnt_drop_write - give up write access to a mount
437  * @mnt: the mount on which to give up write access
462 static int mnt_make_readonly(struct mount *mnt)  in mnt_make_readonly()
504 static int __mnt_unmake_readonly(struct mount *mnt)  in __mnt_unmake_readonly()
514 	struct mount *mnt;  in sb_prepare_remount_readonly()
548 static void free_vfsmnt(struct mount *mnt)  in free_vfsmnt()
559 	free_vfsmnt(container_of(head, struct mount, mnt_rcu));  in delayed_free_vfsmnt()
565 	struct mount *mnt;  in __legitimize_mnt()
605  * find the first mount at @dentry on vfsmount @mnt.
608 struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)  in __lookup_mnt()
611 	struct mount *p;  in __lookup_mnt()
620  * lookup_mnt - Return the first child mount mounted at path
625  * mount /dev/sda1 /mnt
626  * mount /dev/sda2 /mnt
627  * mount /dev/sda3 /mnt
629  * Then lookup_mnt() on the base /mnt dentry in the root mount will
637 	struct mount *child_mnt;  in lookup_mnt()
661 static inline bool mnt_is_cursor(struct mount *mnt)  in mnt_is_cursor()
668  *                         current mount namespace.
673  * mounts in the current mount namespace and test to see if the dentry
677  * need to identify all mounts that may be in the current mount
678  * namespace not just a mount that happens to have some specified
679  * parent mount.
684 	struct mount *mnt;  in __is_local_mountpoint()
790 static inline int check_mnt(struct mount *mnt)  in check_mnt()
820 static struct mountpoint *unhash_mnt(struct mount *mnt)  in unhash_mnt()
836 static void umount_mnt(struct mount *mnt)  in umount_mnt()
844 void mnt_set_mountpoint(struct mount *mnt,  in mnt_set_mountpoint()
846 			struct mount *child_mnt)  in mnt_set_mountpoint()
856 static void __attach_mnt(struct mount *mnt, struct mount *parent)  in __attach_mnt()
866 static void attach_mnt(struct mount *mnt,  in attach_mnt()
867 			struct mount *parent,  in attach_mnt()
874 void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt)  in mnt_change_mountpoint()
877 	struct mount *old_parent = mnt->mnt_parent;  in mnt_change_mountpoint()
892 static void commit_tree(struct mount *mnt)  in commit_tree()
894 	struct mount *parent = mnt->mnt_parent;  in commit_tree()
895 	struct mount *m;  in commit_tree()
914 static struct mount *next_mnt(struct mount *p, struct mount *root)  in next_mnt()
927 	return list_entry(next, struct mount, mnt_child);  in next_mnt()
930 static struct mount *skip_mnt_tree(struct mount *p)  in skip_mnt_tree()
934 		p = list_entry(prev, struct mount, mnt_child);  in skip_mnt_tree()
941  * vfs_create_mount - Create a mount for a configured superblock
944  * Create a mount to an already configured superblock.  If necessary, the
947  * Note that this does not attach the mount to anything.
951 	struct mount *mnt;  in vfs_create_mount()
1022 	 * through from the parent mount to the submount don't support  in vfs_submount()
1032 static struct mount *clone_mnt(struct mount *old, struct dentry *root,  in clone_mnt()
1036 	struct mount *mnt;  in clone_mnt()
1083 	/* stick the duplicate mount on the same expiry list  in clone_mnt()
1098 static void cleanup_mnt(struct mount *mnt)  in cleanup_mnt()
1101 	struct mount *m;  in cleanup_mnt()
1125 	cleanup_mnt(container_of(head, struct mount, mnt_rcu));  in __cleanup_mnt()
1132 	struct mount *m, *t;  in delayed_mntput()
1139 static void mntput_no_expire(struct mount *mnt)  in mntput_no_expire()
1181 		struct mount *p, *tmp;  in mntput_no_expire()
1207 		struct mount *m = real_mount(mnt);  in mntput()
1224 /* path_is_mountpoint() - Check if path is a mount in the current
1255 	struct mount *p;  in mnt_clone_internal()
1264 static struct mount *mnt_list_next(struct mnt_namespace *ns,  in mnt_list_next()
1267 	struct mount *mnt, *ret = NULL;  in mnt_list_next()
1305 	struct mount *mnt = v;  in m_next()
1314 	struct mount *mnt = v;  in m_stop()
1328 	struct mount *r = v;  in m_show()
1339 void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor)  in mnt_cursor_del()
1350  * may_umount_tree - check if a mount tree is busy
1351  * @mnt: root of mount tree
1359 	struct mount *mnt = real_mount(m);  in may_umount_tree()
1362 	struct mount *p;  in may_umount_tree()
1382  * may_umount - check if a mount point is busy
1383  * @mnt: root of mount
1385  * This is called to check if a mount point has any
1387  * mount has sub mounts this will return busy
1412 	struct mount *m;  in namespace_unlock()
1444 static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how)  in disconnect_mount()
1450 	/* A mount without a parent has nothing to be connected to */  in disconnect_mount()
1461 	/* Has it been requested that the mount remain connected? */  in disconnect_mount()
1465 	/* Is the mount locked such that it needs to remain connected? */  in disconnect_mount()
1469 	/* By default disconnect the mount */  in disconnect_mount()
1477 static void umount_tree(struct mount *mnt, enum umount_tree_flags how)  in umount_tree()
1480 	struct mount *p;  in umount_tree()
1503 		p = list_first_entry(&tmp_list, struct mount, mnt_list);  in umount_tree()
1531 static void shrink_submounts(struct mount *mnt);
1556 static int do_umount(struct mount *mnt, int flags)  in do_umount()
1593 	 * mount, and they will themselves hold resources we must  in do_umount()
1597 	 * must return, and the like. Thats for the mount program to worry  in do_umount()
1656  * to an existing mountpoint, and wind up leaking the mount.
1665 	struct mount *mnt;  in __detach_mounts()
1675 		mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);  in __detach_mounts()
1704 	pr_warn("VFS: \"mand\" mount option not supported");  in may_mandlock()
1711 	struct mount *mnt = real_mount(path->mnt);  in can_umount()
1730 	struct mount *mnt = real_mount(path->mnt);  in path_umount()
1776 	/* Is this a proxy for a mount namespace? */  in is_mnt_ns_file()
1793 	/* Could bind mounting the mount namespace inode cause a  in mnt_ns_loop()
1794 	 * mount namespace loop?  in mnt_ns_loop()
1804 struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,  in copy_tree()
1807 	struct mount *res, *p, *q, *r, *parent;  in copy_tree()
1823 		struct mount *s;  in copy_tree()
1873 	struct mount *tree;  in collect_mounts()
1921  * to the originating mount won't be propagated into this).
1927 	struct mount *old_mnt = real_mount(path->mnt);  in clone_private_mount()
1928 	struct mount *new_mnt;  in clone_private_mount()
1937 	/* Longterm mount to be removed by kern_unmount*() */  in clone_private_mount()
1947 	struct mount *mnt;  in iterate_mounts()
1959 static void lock_mnt_tree(struct mount *mnt)  in lock_mnt_tree()
1961 	struct mount *p;  in lock_mnt_tree()
1965 		/* Don't allow unprivileged users to change mount flags */  in lock_mnt_tree()
1979 		/* Don't allow unprivileged users to reveal what is under a mount */  in lock_mnt_tree()
1986 static void cleanup_group_ids(struct mount *mnt, struct mount *end)  in cleanup_group_ids()
1988 	struct mount *p;  in cleanup_group_ids()
1996 static int invent_group_ids(struct mount *mnt, bool recurse)  in invent_group_ids()
1998 	struct mount *p;  in invent_group_ids()
2013 int count_mounts(struct mnt_namespace *ns, struct mount *mnt)  in count_mounts()
2017 	struct mount *p;  in count_mounts()
2036  *  @source_mnt : mount tree to be attached
2037  *  @nd         : place the mount tree @source_mnt is attached
2039  *  		   store the parent mount and mountpoint dentry.
2042  *  NOTE: in the table below explains the semantics when a source mount
2043  *  of a given type is attached to a destination mount of a given type.
2045  * |         BIND MOUNT OPERATION                                            |
2056  * A bind operation clones the source mount and mounts the clone on the
2057  * destination mount.
2059  * (++)  the cloned mount is propagated to all the mounts in the propagation
2060  * 	 tree of the destination mount and the cloned mount is added to
2061  * 	 the peer group of the source mount.
2062  * (+)   the cloned mount is created under the destination mount and is marked
2063  *       as shared. The cloned mount is added to the peer group of the source
2064  *       mount.
2065  * (+++) the mount is propagated to all the mounts in the propagation tree
2066  *       of the destination mount and the cloned mount is made slave
2067  *       of the same master as that of the source mount. The cloned mount
2069  * (*)   the cloned mount is made a slave of the same master as that of the
2070  * 	 source mount.
2073  * |         		MOVE MOUNT OPERATION                                 |
2085  * (+)  the mount is moved to the destination. And is then propagated to
2086  * 	all the mounts in the propagation tree of the destination mount.
2087  * (+*)  the mount is moved to the destination.
2088  * (+++)  the mount is moved to the destination and is then propagated to
2089  * 	all the mounts belonging to the destination mount's propagation tree.
2090  * 	the mount is marked as 'shared and slave'.
2091  * (*)	the mount continues to be a slave at the new location.
2093  * if the source mount is a tree, the operations explained above is
2094  * applied to each mount in the tree.
2098 static int attach_recursive_mnt(struct mount *source_mnt,  in attach_recursive_mnt()
2099 			struct mount *dest_mnt,  in attach_recursive_mnt()
2107 	struct mount *child, *p;  in attach_recursive_mnt()
2118 	/* Is there space to add these mounts to the mount namespace? */  in attach_recursive_mnt()
2152 		struct mount *q;  in attach_recursive_mnt()
2171 		child = hlist_entry(tree_list.first, struct mount, mnt_hash);  in attach_recursive_mnt()
2228 static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp)  in graft_tree()
2262 	struct mount *m;  in do_change_type()
2263 	struct mount *mnt = real_mount(path->mnt);  in do_change_type()
2292 static bool has_locked_children(struct mount *mnt, struct dentry *dentry)  in has_locked_children()
2294 	struct mount *child;  in has_locked_children()
2305 static struct mount *__do_loopback(struct path *old_path, int recurse)  in __do_loopback()
2307 	struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt);  in __do_loopback()
2330  * do loopback mount.
2336 	struct mount *mnt = NULL, *parent;  in do_loopback()
2382 	struct mount *mnt, *p;  in open_detached_copy()
2469  * Don't allow locked mount flags to be cleared.
2474 static bool can_change_locked_flags(struct mount *mnt, unsigned int mnt_flags)  in can_change_locked_flags()
2501 static int change_mount_ro_state(struct mount *mnt, unsigned int mnt_flags)  in change_mount_ro_state()
2515  * Update the user-settable attributes on a mount.  The caller must hold
2518 static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags)  in set_mount_attributes()
2552  * to mount(2).
2557 	struct mount *mnt = real_mount(path->mnt);  in do_reconfigure_mnt()
2590 	struct mount *mnt = real_mount(path->mnt);  in do_remount()
2625 static inline int tree_contains_unbindable(struct mount *mnt)  in tree_contains_unbindable()
2627 	struct mount *p;  in tree_contains_unbindable()
2636  * Check that there aren't references to earlier/same mount namespaces in the
2637  * specified subtree.  Such references can act as pins for mount namespaces
2638  * that aren't checked by the mount-cycle checking code, thereby allowing
2641 static bool check_for_nsfs_mounts(struct mount *subtree)  in check_for_nsfs_mounts()
2643 	struct mount *p;  in check_for_nsfs_mounts()
2660 	struct mount *p;  in do_move_mount()
2661 	struct mount *old;  in do_move_mount()
2662 	struct mount *parent;  in do_move_mount()
2701 	 * Don't move a mount residing in a shared parent.  in do_move_mount()
2706 	 * Don't move a mount tree containing unbindable mounts to a destination  in do_move_mount()
2707 	 * mount which is shared.  in do_move_mount()
2723 	/* if the mount is moved, it should no longer be expire  in do_move_mount()
2757  * add a mount into a namespace's mount tree
2759 static int do_add_mount(struct mount *newmnt, struct mountpoint *mp,  in do_add_mount()
2762 	struct mount *parent = real_mount(path->mnt);  in do_add_mount()
2775 	/* Refuse the same filesystem on the same mount point */  in do_add_mount()
2790  * Create a new mount using a superblock configuration and request it
2831  * create a new mount for userspace and request it to be added into the
2887 	struct mount *mnt;  in finish_automount()
2896 	/* The new mount record should have at least 2 refs to prevent it being  in finish_automount()
2910 	 * got", not "try to mount it on top".  in finish_automount()
2954  * mnt_set_expiry - Put a mount on an expiration list
2955  * @mnt: The mount to list.
2956  * @expiry_list: The list to add the mount to.
2975 	struct mount *mnt, *next;  in mark_mounts_for_expiry()
2997 		mnt = list_first_entry(&graveyard, struct mount, mnt_expire);  in mark_mounts_for_expiry()
3013 static int select_submounts(struct mount *parent, struct list_head *graveyard)  in select_submounts()
3015 	struct mount *this_parent = parent;  in select_submounts()
3024 		struct mount *mnt = list_entry(tmp, struct mount, mnt_child);  in select_submounts()
3059 static void shrink_submounts(struct mount *mnt)  in shrink_submounts()
3062 	struct mount *m;  in shrink_submounts()
3067 			m = list_first_entry(&graveyard, struct mount,  in shrink_submounts()
3118  * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
3124  * Pre-0.97 versions of mount() didn't have a flags word.
3244  * mount a reference to an older mount namespace into the current
3245  * mount namespace, preventing reference counting loops.  A 64bit
3292 	struct mount *p, *q;  in copy_mnt_ns()
3293 	struct mount *old;  in copy_mnt_ns()
3294 	struct mount *new;  in copy_mnt_ns()
3368 	struct mount *mnt = real_mount(m);  in mount_subtree()
3403 SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,  in SYSCALL_DEFINE5()  argument
3438  * Create a kernel mount representation for a new, prepared superblock
3448 	struct mount *mnt;  in SYSCALL_DEFINE3()
3505 	/* There must be a valid superblock or we can't mount it */  in SYSCALL_DEFINE3()
3512 		pr_warn("VFS: Mount too revealing\n");  in SYSCALL_DEFINE3()
3532 	/* We've done the mount bit - now move the file context into more or  in SYSCALL_DEFINE3()
3578  * Move a mount from one place to another.  In combination with
3579  * fsopen()/fsmount() this is used to install a new mount and in combination
3581  * a mount subtree.
3640 bool is_path_reachable(struct mount *mnt, struct dentry *dentry,  in is_path_reachable()
3681  *    /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
3682  *    though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
3689 	struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent;  in SYSCALL_DEFINE2()
3758 	/* mount old root on put_old */  in SYSCALL_DEFINE2()
3760 	/* mount new_root on / */  in SYSCALL_DEFINE2()
3764 	/* A moved mount should not expire automatically */  in SYSCALL_DEFINE2()
3787 	struct mount *m;  in init_mount_tree()
3818 	mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount),  in mnt_init()
3821 	mount_hashtable = alloc_large_system_hash("Mount-cache",  in mnt_init()
3833 		panic("Failed to allocate mount hash table\n");  in mnt_init()
3863 		 * it is a longterm mount, don't release mnt until  in kern_mount()
3874 	/* release long term mount so mount point can be released */  in kern_unmount()
3930 	struct mount *mnt;  in mnt_already_visible()
3936 		struct mount *child;  in mnt_already_visible()
3945 		/* This mount is not fully visible if it's root directory  in mnt_already_visible()
3951 		/* A local view of the mount flags */  in mnt_already_visible()
3958 		/* Verify the mount flags are equal to or more permissive  in mnt_already_visible()
3959 		 * than the proposed new mount.  in mnt_already_visible()
3968 		/* This mount is not fully visible if there are any  in mnt_already_visible()