31 #include <uapi/linux/mount.h>
38 /* Maximum number of mounts in a mount namespace */
125 static int mnt_alloc_id(struct mount *mnt)  in mnt_alloc_id()
135 static void mnt_free_id(struct mount *mnt)  in mnt_free_id()
143 static int mnt_alloc_group_id(struct mount *mnt)  in mnt_alloc_group_id()
156 void mnt_release_group_id(struct mount *mnt)  in mnt_release_group_id()
165 static inline void mnt_add_count(struct mount *mnt, int n)  in mnt_add_count()
179 int mnt_get_count(struct mount *mnt)  in mnt_get_count()
195 static struct mount *alloc_vfsmnt(const char *name)  in alloc_vfsmnt()
197 	struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);  in alloc_vfsmnt()
258  * __mnt_is_readonly: check whether a mount is read-only
259  * @mnt: the mount to check for its write status
274 static inline void mnt_inc_writers(struct mount *mnt)  in mnt_inc_writers()
283 static inline void mnt_dec_writers(struct mount *mnt)  in mnt_dec_writers()
292 static unsigned int mnt_get_writers(struct mount *mnt)  in mnt_get_writers()
324  * __mnt_want_write - get write access to a mount without freeze protection
325  * @m: the mount on which to take a write
335 	struct mount *mnt = real_mount(m);  in __mnt_want_write()
364  * mnt_want_write - get write access to a mount
365  * @m: the mount on which to take a write
368  * it, and makes sure that writes are allowed (mount is read-write, filesystem
385  * __mnt_want_write_file - get write access to a file's mount
386  * @file: the file who's mount on which to take a write
408  * mnt_want_write_file - get write access to a file's mount
409  * @file: the file who's mount on which to take a write
429  * __mnt_drop_write - give up write access to a mount
430  * @mnt: the mount on which to give up write access
444  * mnt_drop_write - give up write access to a mount
445  * @mnt: the mount on which to give up write access
471 static inline int mnt_hold_writers(struct mount *mnt)  in mnt_hold_writers()
502 static inline void mnt_unhold_writers(struct mount *mnt)  in mnt_unhold_writers()
512 static int mnt_make_readonly(struct mount *mnt)  in mnt_make_readonly()
525 	struct mount *mnt;  in sb_prepare_remount_readonly()
559 static void free_vfsmnt(struct mount *mnt)  in free_vfsmnt()
575 	free_vfsmnt(container_of(head, struct mount, mnt_rcu));  in delayed_free_vfsmnt()
581 	struct mount *mnt;  in __legitimize_mnt()
621  * find the first mount at @dentry on vfsmount @mnt.
624 struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)  in __lookup_mnt()
627 	struct mount *p;  in __lookup_mnt()
636  * lookup_mnt - Return the first child mount mounted at path
641  * mount /dev/sda1 /mnt
642  * mount /dev/sda2 /mnt
643  * mount /dev/sda3 /mnt
645  * Then lookup_mnt() on the base /mnt dentry in the root mount will
653 	struct mount *child_mnt;  in lookup_mnt()
677 static inline bool mnt_is_cursor(struct mount *mnt)  in mnt_is_cursor()
684  *                         current mount namespace.
689  * mounts in the current mount namespace and test to see if the dentry
693  * need to identify all mounts that may be in the current mount
694  * namespace not just a mount that happens to have some specified
695  * parent mount.
700 	struct mount *mnt;  in __is_local_mountpoint()
806 static inline int check_mnt(struct mount *mnt)  in check_mnt()
836 static struct mountpoint *unhash_mnt(struct mount *mnt)  in unhash_mnt()
852 static void umount_mnt(struct mount *mnt)  in umount_mnt()
860 void mnt_set_mountpoint(struct mount *mnt,  in mnt_set_mountpoint()
862 			struct mount *child_mnt)  in mnt_set_mountpoint()
872 static void __attach_mnt(struct mount *mnt, struct mount *parent)  in __attach_mnt()
882 static void attach_mnt(struct mount *mnt,  in attach_mnt()
883 			struct mount *parent,  in attach_mnt()
890 void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt)  in mnt_change_mountpoint()
893 	struct mount *old_parent = mnt->mnt_parent;  in mnt_change_mountpoint()
908 static void commit_tree(struct mount *mnt)  in commit_tree()
910 	struct mount *parent = mnt->mnt_parent;  in commit_tree()
911 	struct mount *m;  in commit_tree()
930 static struct mount *next_mnt(struct mount *p, struct mount *root)  in next_mnt()
943 	return list_entry(next, struct mount, mnt_child);  in next_mnt()
946 static struct mount *skip_mnt_tree(struct mount *p)  in skip_mnt_tree()
950 		p = list_entry(prev, struct mount, mnt_child);  in skip_mnt_tree()
957  * vfs_create_mount - Create a mount for a configured superblock
960  * Create a mount to an already configured superblock.  If necessary, the
963  * Note that this does not attach the mount to anything.
967 	struct mount *mnt;  in vfs_create_mount()
1038 	 * through from the parent mount to the submount don't support  in vfs_submount()
1048 static struct mount *clone_mnt(struct mount *old, struct dentry *root,  in clone_mnt()
1052 	struct mount *mnt;  in clone_mnt()
1102 	/* stick the duplicate mount on the same expiry list  in clone_mnt()
1117 static void cleanup_mnt(struct mount *mnt)  in cleanup_mnt()
1120 	struct mount *m;  in cleanup_mnt()
1144 	cleanup_mnt(container_of(head, struct mount, mnt_rcu));  in __cleanup_mnt()
1151 	struct mount *m, *t;  in delayed_mntput()
1158 static void mntput_no_expire(struct mount *mnt)  in mntput_no_expire()
1203 		struct mount *p, *tmp;  in mntput_no_expire()
1229 		struct mount *m = real_mount(mnt);  in mntput()
1247  * path_is_mountpoint() - Check if path is a mount in the current namespace.
1278 	struct mount *p;  in mnt_clone_internal()
1287 static struct mount *mnt_list_next(struct mnt_namespace *ns,  in mnt_list_next()
1290 	struct mount *mnt, *ret = NULL;  in mnt_list_next()
1328 	struct mount *mnt = v;  in m_next()
1337 	struct mount *mnt = v;  in m_stop()
1351 	struct mount *r = v;  in m_show()
1362 void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor)  in mnt_cursor_del()
1373  * may_umount_tree - check if a mount tree is busy
1374  * @m: root of mount tree
1382 	struct mount *mnt = real_mount(m);  in may_umount_tree()
1385 	struct mount *p;  in may_umount_tree()
1405  * may_umount - check if a mount point is busy
1406  * @mnt: root of mount
1408  * This is called to check if a mount point has any
1410  * mount has sub mounts this will return busy
1435 	struct mount *m;  in namespace_unlock()
1467 static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how)  in disconnect_mount()
1473 	/* A mount without a parent has nothing to be connected to */  in disconnect_mount()
1484 	/* Has it been requested that the mount remain connected? */  in disconnect_mount()
1488 	/* Is the mount locked such that it needs to remain connected? */  in disconnect_mount()
1492 	/* By default disconnect the mount */  in disconnect_mount()
1500 static void umount_tree(struct mount *mnt, enum umount_tree_flags how)  in umount_tree()
1503 	struct mount *p;  in umount_tree()
1526 		p = list_first_entry(&tmp_list, struct mount, mnt_list);  in umount_tree()
1554 static void shrink_submounts(struct mount *mnt);
1579 static int do_umount(struct mount *mnt, int flags)  in do_umount()
1616 	 * mount, and they will themselves hold resources we must  in do_umount()
1620 	 * must return, and the like. Thats for the mount program to worry  in do_umount()
1679  * to an existing mountpoint, and wind up leaking the mount.
1688 	struct mount *mnt;  in __detach_mounts()
1698 		mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);  in __detach_mounts()
1722 		     "WARNING: The mand mount option has been deprecated and\n"  in warn_mandlock()
1724 		     "         option from the mount to silence this warning.\n"  in warn_mandlock()
1730 	struct mount *mnt = real_mount(path->mnt);  in can_umount()
1748 	struct mount *mnt = real_mount(path->mnt);  in path_umount()
1798 	/* Is this a proxy for a mount namespace? */  in is_mnt_ns_file()
1815 	/* Could bind mounting the mount namespace inode cause a  in mnt_ns_loop()
1816 	 * mount namespace loop?  in mnt_ns_loop()
1826 struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,  in copy_tree()
1829 	struct mount *res, *p, *q, *r, *parent;  in copy_tree()
1845 		struct mount *s;  in copy_tree()
1895 	struct mount *tree;  in collect_mounts()
1938 static bool has_locked_children(struct mount *mnt, struct dentry *dentry)  in has_locked_children()
1940 	struct mount *child;  in has_locked_children()
1956  * This creates a new vfsmount, which will be the clone of @path.  The new mount
1958  * changes to the originating mount won't be propagated into this).
1964 	struct mount *old_mnt = real_mount(path->mnt);  in clone_private_mount()
1965 	struct mount *new_mnt;  in clone_private_mount()
1983 	/* Longterm mount to be removed by kern_unmount*() */  in clone_private_mount()
1997 	struct mount *mnt;  in iterate_mounts()
2009 static void lock_mnt_tree(struct mount *mnt)  in lock_mnt_tree()
2011 	struct mount *p;  in lock_mnt_tree()
2015 		/* Don't allow unprivileged users to change mount flags */  in lock_mnt_tree()
2029 		/* Don't allow unprivileged users to reveal what is under a mount */  in lock_mnt_tree()
2036 static void cleanup_group_ids(struct mount *mnt, struct mount *end)  in cleanup_group_ids()
2038 	struct mount *p;  in cleanup_group_ids()
2046 static int invent_group_ids(struct mount *mnt, bool recurse)  in invent_group_ids()
2048 	struct mount *p;  in invent_group_ids()
2063 int count_mounts(struct mnt_namespace *ns, struct mount *mnt)  in count_mounts()
2067 	struct mount *p;  in count_mounts()
2086  *  @source_mnt : mount tree to be attached
2087  *  @nd         : place the mount tree @source_mnt is attached
2089  *  		   store the parent mount and mountpoint dentry.
2092  *  NOTE: in the table below explains the semantics when a source mount
2093  *  of a given type is attached to a destination mount of a given type.
2095  * |         BIND MOUNT OPERATION                                            |
2106  * A bind operation clones the source mount and mounts the clone on the
2107  * destination mount.
2109  * (++)  the cloned mount is propagated to all the mounts in the propagation
2110  * 	 tree of the destination mount and the cloned mount is added to
2111  * 	 the peer group of the source mount.
2112  * (+)   the cloned mount is created under the destination mount and is marked
2113  *       as shared. The cloned mount is added to the peer group of the source
2114  *       mount.
2115  * (+++) the mount is propagated to all the mounts in the propagation tree
2116  *       of the destination mount and the cloned mount is made slave
2117  *       of the same master as that of the source mount. The cloned mount
2119  * (*)   the cloned mount is made a slave of the same master as that of the
2120  * 	 source mount.
2123  * |         		MOVE MOUNT OPERATION                                 |
2135  * (+)  the mount is moved to the destination. And is then propagated to
2136  * 	all the mounts in the propagation tree of the destination mount.
2137  * (+*)  the mount is moved to the destination.
2138  * (+++)  the mount is moved to the destination and is then propagated to
2139  * 	all the mounts belonging to the destination mount's propagation tree.
2140  * 	the mount is marked as 'shared and slave'.
2141  * (*)	the mount continues to be a slave at the new location.
2143  * if the source mount is a tree, the operations explained above is
2144  * applied to each mount in the tree.
2148 static int attach_recursive_mnt(struct mount *source_mnt,  in attach_recursive_mnt()
2149 			struct mount *dest_mnt,  in attach_recursive_mnt()
2157 	struct mount *child, *p;  in attach_recursive_mnt()
2168 	/* Is there space to add these mounts to the mount namespace? */  in attach_recursive_mnt()
2202 		struct mount *q;  in attach_recursive_mnt()
2221 		child = hlist_entry(tree_list.first, struct mount, mnt_hash);  in attach_recursive_mnt()
2278 static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp)  in graft_tree()
2312 	struct mount *m;  in do_change_type()
2313 	struct mount *mnt = real_mount(path->mnt);  in do_change_type()
2342 static struct mount *__do_loopback(struct path *old_path, int recurse)  in __do_loopback()
2344 	struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt);  in __do_loopback()
2367  * do loopback mount.
2373 	struct mount *mnt = NULL, *parent;  in do_loopback()
2419 	struct mount *mnt, *p;  in open_detached_copy()
2506  * Don't allow locked mount flags to be cleared.
2511 static bool can_change_locked_flags(struct mount *mnt, unsigned int mnt_flags)  in can_change_locked_flags()
2538 static int change_mount_ro_state(struct mount *mnt, unsigned int mnt_flags)  in change_mount_ro_state()
2552 static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags)  in set_mount_attributes()
2584  * to mount(2).
2589 	struct mount *mnt = real_mount(path->mnt);  in do_reconfigure_mnt()
2628 	struct mount *mnt = real_mount(path->mnt);  in do_remount()
2666 static inline int tree_contains_unbindable(struct mount *mnt)  in tree_contains_unbindable()
2668 	struct mount *p;  in tree_contains_unbindable()
2677  * Check that there aren't references to earlier/same mount namespaces in the
2678  * specified subtree.  Such references can act as pins for mount namespaces
2679  * that aren't checked by the mount-cycle checking code, thereby allowing
2682 static bool check_for_nsfs_mounts(struct mount *subtree)  in check_for_nsfs_mounts()
2684 	struct mount *p;  in check_for_nsfs_mounts()
2700 	struct mount *from, *to;  in do_set_group()
2716 	/* We should be allowed to modify mount namespaces of both mounts */  in do_set_group()
2723 	/* To and From paths should be mount roots */  in do_set_group()
2733 	/* From mount root should be wider than To mount root */  in do_set_group()
2737 	/* From mount should not have locked children in place of To's root */  in do_set_group()
2750 		struct mount *m = from->mnt_master;  in do_set_group()
2773 	struct mount *p;  in do_move_mount()
2774 	struct mount *old;  in do_move_mount()
2775 	struct mount *parent;  in do_move_mount()
2814 	 * Don't move a mount residing in a shared parent.  in do_move_mount()
2819 	 * Don't move a mount tree containing unbindable mounts to a destination  in do_move_mount()
2820 	 * mount which is shared.  in do_move_mount()
2836 	/* if the mount is moved, it should no longer be expire  in do_move_mount()
2870  * add a mount into a namespace's mount tree
2872 static int do_add_mount(struct mount *newmnt, struct mountpoint *mp,  in do_add_mount()
2875 	struct mount *parent = real_mount(path->mnt);  in do_add_mount()
2888 	/* Refuse the same filesystem on the same mount point */  in do_add_mount()
2903  * Create a new mount using a superblock configuration and request it
2944  * create a new mount for userspace and request it to be added into the
3000 	struct mount *mnt;  in finish_automount()
3009 	/* The new mount record should have at least 2 refs to prevent it being  in finish_automount()
3023 	 * got", not "try to mount it on top".  in finish_automount()
3067  * mnt_set_expiry - Put a mount on an expiration list
3068  * @mnt: The mount to list.
3069  * @expiry_list: The list to add the mount to.
3088 	struct mount *mnt, *next;  in mark_mounts_for_expiry()
3110 		mnt = list_first_entry(&graveyard, struct mount, mnt_expire);  in mark_mounts_for_expiry()
3126 static int select_submounts(struct mount *parent, struct list_head *graveyard)  in select_submounts()
3128 	struct mount *this_parent = parent;  in select_submounts()
3137 		struct mount *mnt = list_entry(tmp, struct mount, mnt_child);  in select_submounts()
3172 static void shrink_submounts(struct mount *mnt)  in shrink_submounts()
3175 	struct mount *m;  in shrink_submounts()
3180 			m = list_first_entry(&graveyard, struct mount,  in shrink_submounts()
3231  * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
3237  * Pre-0.97 versions of mount() didn't have a flags word.
3357  * mount a reference to an older mount namespace into the current
3358  * mount namespace, preventing reference counting loops.  A 64bit
3405 	struct mount *p, *q;  in copy_mnt_ns()
3406 	struct mount *old;  in copy_mnt_ns()
3407 	struct mount *new;  in copy_mnt_ns()
3481 	struct mount *mnt = real_mount(m);  in mount_subtree()
3516 SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,  in SYSCALL_DEFINE5()  argument
3581  * Create a kernel mount representation for a new, prepared superblock
3591 	struct mount *mnt;  in SYSCALL_DEFINE3()
3634 	/* There must be a valid superblock or we can't mount it */  in SYSCALL_DEFINE3()
3641 		pr_warn("VFS: Mount too revealing\n");  in SYSCALL_DEFINE3()
3660 	/* We've done the mount bit - now move the file context into more or  in SYSCALL_DEFINE3()
3706  * Move a mount from one place to another.  In combination with
3707  * fsopen()/fsmount() this is used to install a new mount and in combination
3709  * a mount subtree.
3771 bool is_path_reachable(struct mount *mnt, struct dentry *dentry,  in is_path_reachable()
3812  *    /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
3813  *    though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
3820 	struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent;  in SYSCALL_DEFINE2()
3889 	/* mount old root on put_old */  in SYSCALL_DEFINE2()
3891 	/* mount new_root on / */  in SYSCALL_DEFINE2()
3895 	/* A moved mount should not expire automatically */  in SYSCALL_DEFINE2()
3915 static unsigned int recalc_flags(struct mount_kattr *kattr, struct mount *mnt)  in recalc_flags()
3927 static int can_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt)  in can_idmap_mount()
3935 	 * Once a mount has been idmapped we don't allow it to change its  in can_idmap_mount()
3937 	 * another bind-mount they can idmap if they want to.  in can_idmap_mount()
3954 	/* Mount has already been visible in the filesystem hierarchy. */  in can_idmap_mount()
3961 static struct mount *mount_setattr_prepare(struct mount_kattr *kattr,  in mount_setattr_prepare()
3962 					   struct mount *mnt, int *err)  in mount_setattr_prepare()
3964 	struct mount *m = mnt, *last = NULL;  in mount_setattr_prepare()
4003 static void do_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt)  in do_idmap_mount()
4016 				 struct mount *mnt, struct mount *last,  in mount_setattr_commit()
4019 	struct mount *m = mnt;  in mount_setattr_commit()
4033 		 * apply mount options.  in mount_setattr_commit()
4043 		 * On failure, only cleanup until we found the first mount  in mount_setattr_commit()
4056 	struct mount *mnt = real_mount(path->mnt), *last = NULL;  in do_mount_setattr()
4080 	 * Get the mount tree in a shape where we can change mount  in do_mount_setattr()
4110 	 * We currently do not support clearing an idmapped mount. If this ever  in build_mount_idmapped()
4138 	 * wanting to idmap a mount to init_user_ns can just use a namespace  in build_mount_idmapped()
4278 	struct mount *m;  in init_mount_tree()
4309 	mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount),  in mnt_init()
4312 	mount_hashtable = alloc_large_system_hash("Mount-cache",  in mnt_init()
4324 		panic("Failed to allocate mount hash table\n");  in mnt_init()
4354 		 * it is a longterm mount, don't release mnt until  in kern_mount()
4365 	/* release long term mount so mount point can be released */  in kern_unmount()
4421 	struct mount *mnt;  in mnt_already_visible()
4427 		struct mount *child;  in mnt_already_visible()
4436 		/* This mount is not fully visible if it's root directory  in mnt_already_visible()
4442 		/* A local view of the mount flags */  in mnt_already_visible()
4449 		/* Verify the mount flags are equal to or more permissive  in mnt_already_visible()
4450 		 * than the proposed new mount.  in mnt_already_visible()
4459 		/* This mount is not fully visible if there are any  in mnt_already_visible()