4 * (C) Copyright Al Viro 2000, 2001
5 * Released under GPL v2.
7 * Based on code from fs/super.c, copyright Linus Torvalds and others.
11 #include <linux/syscalls.h>
12 #include <linux/export.h>
13 #include <linux/capability.h>
14 #include <linux/mnt_namespace.h>
15 #include <linux/user_namespace.h>
16 #include <linux/namei.h>
17 #include <linux/security.h>
18 #include <linux/idr.h>
19 #include <linux/init.h> /* init_rootfs */
20 #include <linux/fs_struct.h> /* get_fs_root et.al. */
21 #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */
22 #include <linux/uaccess.h>
23 #include <linux/proc_ns.h>
24 #include <linux/magic.h>
25 #include <linux/bootmem.h>
26 #include <linux/task_work.h>
30 /* Maximum number of mounts in a mount namespace */
31 unsigned int sysctl_mount_max __read_mostly
= 100000;
33 static unsigned int m_hash_mask __read_mostly
;
34 static unsigned int m_hash_shift __read_mostly
;
35 static unsigned int mp_hash_mask __read_mostly
;
36 static unsigned int mp_hash_shift __read_mostly
;
38 static __initdata
unsigned long mhash_entries
;
39 static int __init
set_mhash_entries(char *str
)
43 mhash_entries
= simple_strtoul(str
, &str
, 0);
46 __setup("mhash_entries=", set_mhash_entries
);
48 static __initdata
unsigned long mphash_entries
;
49 static int __init
set_mphash_entries(char *str
)
53 mphash_entries
= simple_strtoul(str
, &str
, 0);
56 __setup("mphash_entries=", set_mphash_entries
);
59 static DEFINE_IDA(mnt_id_ida
);
60 static DEFINE_IDA(mnt_group_ida
);
61 static DEFINE_SPINLOCK(mnt_id_lock
);
62 static int mnt_id_start
= 0;
63 static int mnt_group_start
= 1;
65 static struct hlist_head
*mount_hashtable __read_mostly
;
66 static struct hlist_head
*mountpoint_hashtable __read_mostly
;
67 static struct kmem_cache
*mnt_cache __read_mostly
;
68 static DECLARE_RWSEM(namespace_sem
);
71 struct kobject
*fs_kobj
;
72 EXPORT_SYMBOL_GPL(fs_kobj
);
75 * vfsmount lock may be taken for read to prevent changes to the
76 * vfsmount hash, ie. during mountpoint lookups or walking back
79 * It should be taken for write in all cases where the vfsmount
80 * tree or hash is modified or when a vfsmount structure is modified.
82 __cacheline_aligned_in_smp
DEFINE_SEQLOCK(mount_lock
);
84 static inline struct hlist_head
*m_hash(struct vfsmount
*mnt
, struct dentry
*dentry
)
86 unsigned long tmp
= ((unsigned long)mnt
/ L1_CACHE_BYTES
);
87 tmp
+= ((unsigned long)dentry
/ L1_CACHE_BYTES
);
88 tmp
= tmp
+ (tmp
>> m_hash_shift
);
89 return &mount_hashtable
[tmp
& m_hash_mask
];
92 static inline struct hlist_head
*mp_hash(struct dentry
*dentry
)
94 unsigned long tmp
= ((unsigned long)dentry
/ L1_CACHE_BYTES
);
95 tmp
= tmp
+ (tmp
>> mp_hash_shift
);
96 return &mountpoint_hashtable
[tmp
& mp_hash_mask
];
99 static int mnt_alloc_id(struct mount
*mnt
)
104 ida_pre_get(&mnt_id_ida
, GFP_KERNEL
);
105 spin_lock(&mnt_id_lock
);
106 res
= ida_get_new_above(&mnt_id_ida
, mnt_id_start
, &mnt
->mnt_id
);
108 mnt_id_start
= mnt
->mnt_id
+ 1;
109 spin_unlock(&mnt_id_lock
);
116 static void mnt_free_id(struct mount
*mnt
)
118 int id
= mnt
->mnt_id
;
119 spin_lock(&mnt_id_lock
);
120 ida_remove(&mnt_id_ida
, id
);
121 if (mnt_id_start
> id
)
123 spin_unlock(&mnt_id_lock
);
127 * Allocate a new peer group ID
129 * mnt_group_ida is protected by namespace_sem
131 static int mnt_alloc_group_id(struct mount
*mnt
)
135 if (!ida_pre_get(&mnt_group_ida
, GFP_KERNEL
))
138 res
= ida_get_new_above(&mnt_group_ida
,
142 mnt_group_start
= mnt
->mnt_group_id
+ 1;
148 * Release a peer group ID
150 void mnt_release_group_id(struct mount
*mnt
)
152 int id
= mnt
->mnt_group_id
;
153 ida_remove(&mnt_group_ida
, id
);
154 if (mnt_group_start
> id
)
155 mnt_group_start
= id
;
156 mnt
->mnt_group_id
= 0;
160 * vfsmount lock must be held for read
162 static inline void mnt_add_count(struct mount
*mnt
, int n
)
165 this_cpu_add(mnt
->mnt_pcp
->mnt_count
, n
);
174 * vfsmount lock must be held for write
176 unsigned int mnt_get_count(struct mount
*mnt
)
179 unsigned int count
= 0;
182 for_each_possible_cpu(cpu
) {
183 count
+= per_cpu_ptr(mnt
->mnt_pcp
, cpu
)->mnt_count
;
188 return mnt
->mnt_count
;
192 static void drop_mountpoint(struct fs_pin
*p
)
194 struct mount
*m
= container_of(p
, struct mount
, mnt_umount
);
195 dput(m
->mnt_ex_mountpoint
);
200 static struct mount
*alloc_vfsmnt(const char *name
)
202 struct mount
*mnt
= kmem_cache_zalloc(mnt_cache
, GFP_KERNEL
);
206 err
= mnt_alloc_id(mnt
);
211 mnt
->mnt_devname
= kstrdup_const(name
, GFP_KERNEL
);
212 if (!mnt
->mnt_devname
)
217 mnt
->mnt_pcp
= alloc_percpu(struct mnt_pcp
);
219 goto out_free_devname
;
221 this_cpu_add(mnt
->mnt_pcp
->mnt_count
, 1);
224 mnt
->mnt_writers
= 0;
227 INIT_HLIST_NODE(&mnt
->mnt_hash
);
228 INIT_LIST_HEAD(&mnt
->mnt_child
);
229 INIT_LIST_HEAD(&mnt
->mnt_mounts
);
230 INIT_LIST_HEAD(&mnt
->mnt_list
);
231 INIT_LIST_HEAD(&mnt
->mnt_expire
);
232 INIT_LIST_HEAD(&mnt
->mnt_share
);
233 INIT_LIST_HEAD(&mnt
->mnt_slave_list
);
234 INIT_LIST_HEAD(&mnt
->mnt_slave
);
235 INIT_HLIST_NODE(&mnt
->mnt_mp_list
);
236 #ifdef CONFIG_FSNOTIFY
237 INIT_HLIST_HEAD(&mnt
->mnt_fsnotify_marks
);
239 init_fs_pin(&mnt
->mnt_umount
, drop_mountpoint
);
245 kfree_const(mnt
->mnt_devname
);
250 kmem_cache_free(mnt_cache
, mnt
);
255 * Most r/o checks on a fs are for operations that take
256 * discrete amounts of time, like a write() or unlink().
257 * We must keep track of when those operations start
258 * (for permission checks) and when they end, so that
259 * we can determine when writes are able to occur to
263 * __mnt_is_readonly: check whether a mount is read-only
264 * @mnt: the mount to check for its write status
266 * This shouldn't be used directly ouside of the VFS.
267 * It does not guarantee that the filesystem will stay
268 * r/w, just that it is right *now*. This can not and
269 * should not be used in place of IS_RDONLY(inode).
270 * mnt_want/drop_write() will _keep_ the filesystem
273 int __mnt_is_readonly(struct vfsmount
*mnt
)
275 if (mnt
->mnt_flags
& MNT_READONLY
)
277 if (mnt
->mnt_sb
->s_flags
& MS_RDONLY
)
281 EXPORT_SYMBOL_GPL(__mnt_is_readonly
);
283 static inline void mnt_inc_writers(struct mount
*mnt
)
286 this_cpu_inc(mnt
->mnt_pcp
->mnt_writers
);
292 static inline void mnt_dec_writers(struct mount
*mnt
)
295 this_cpu_dec(mnt
->mnt_pcp
->mnt_writers
);
301 static unsigned int mnt_get_writers(struct mount
*mnt
)
304 unsigned int count
= 0;
307 for_each_possible_cpu(cpu
) {
308 count
+= per_cpu_ptr(mnt
->mnt_pcp
, cpu
)->mnt_writers
;
313 return mnt
->mnt_writers
;
317 static int mnt_is_readonly(struct vfsmount
*mnt
)
319 if (mnt
->mnt_sb
->s_readonly_remount
)
321 /* Order wrt setting s_flags/s_readonly_remount in do_remount() */
323 return __mnt_is_readonly(mnt
);
327 * Most r/o & frozen checks on a fs are for operations that take discrete
328 * amounts of time, like a write() or unlink(). We must keep track of when
329 * those operations start (for permission checks) and when they end, so that we
330 * can determine when writes are able to occur to a filesystem.
333 * __mnt_want_write - get write access to a mount without freeze protection
334 * @m: the mount on which to take a write
336 * This tells the low-level filesystem that a write is about to be performed to
337 * it, and makes sure that writes are allowed (mnt it read-write) before
338 * returning success. This operation does not protect against filesystem being
339 * frozen. When the write operation is finished, __mnt_drop_write() must be
340 * called. This is effectively a refcount.
342 int __mnt_want_write(struct vfsmount
*m
)
344 struct mount
*mnt
= real_mount(m
);
348 mnt_inc_writers(mnt
);
350 * The store to mnt_inc_writers must be visible before we pass
351 * MNT_WRITE_HOLD loop below, so that the slowpath can see our
352 * incremented count after it has set MNT_WRITE_HOLD.
355 while (ACCESS_ONCE(mnt
->mnt
.mnt_flags
) & MNT_WRITE_HOLD
)
358 * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
359 * be set to match its requirements. So we must not load that until
360 * MNT_WRITE_HOLD is cleared.
363 if (mnt_is_readonly(m
)) {
364 mnt_dec_writers(mnt
);
373 * mnt_want_write - get write access to a mount
374 * @m: the mount on which to take a write
376 * This tells the low-level filesystem that a write is about to be performed to
377 * it, and makes sure that writes are allowed (mount is read-write, filesystem
378 * is not frozen) before returning success. When the write operation is
379 * finished, mnt_drop_write() must be called. This is effectively a refcount.
381 int mnt_want_write(struct vfsmount
*m
)
385 sb_start_write(m
->mnt_sb
);
386 ret
= __mnt_want_write(m
);
388 sb_end_write(m
->mnt_sb
);
391 EXPORT_SYMBOL_GPL(mnt_want_write
);
394 * mnt_clone_write - get write access to a mount
395 * @mnt: the mount on which to take a write
397 * This is effectively like mnt_want_write, except
398 * it must only be used to take an extra write reference
399 * on a mountpoint that we already know has a write reference
400 * on it. This allows some optimisation.
402 * After finished, mnt_drop_write must be called as usual to
403 * drop the reference.
405 int mnt_clone_write(struct vfsmount
*mnt
)
407 /* superblock may be r/o */
408 if (__mnt_is_readonly(mnt
))
411 mnt_inc_writers(real_mount(mnt
));
415 EXPORT_SYMBOL_GPL(mnt_clone_write
);
418 * __mnt_want_write_file - get write access to a file's mount
419 * @file: the file who's mount on which to take a write
421 * This is like __mnt_want_write, but it takes a file and can
422 * do some optimisations if the file is open for write already
424 int __mnt_want_write_file(struct file
*file
)
426 if (!(file
->f_mode
& FMODE_WRITER
))
427 return __mnt_want_write(file
->f_path
.mnt
);
429 return mnt_clone_write(file
->f_path
.mnt
);
433 * mnt_want_write_file - get write access to a file's mount
434 * @file: the file who's mount on which to take a write
436 * This is like mnt_want_write, but it takes a file and can
437 * do some optimisations if the file is open for write already
439 int mnt_want_write_file(struct file
*file
)
443 sb_start_write(file
->f_path
.mnt
->mnt_sb
);
444 ret
= __mnt_want_write_file(file
);
446 sb_end_write(file
->f_path
.mnt
->mnt_sb
);
449 EXPORT_SYMBOL_GPL(mnt_want_write_file
);
452 * __mnt_drop_write - give up write access to a mount
453 * @mnt: the mount on which to give up write access
455 * Tells the low-level filesystem that we are done
456 * performing writes to it. Must be matched with
457 * __mnt_want_write() call above.
459 void __mnt_drop_write(struct vfsmount
*mnt
)
462 mnt_dec_writers(real_mount(mnt
));
467 * mnt_drop_write - give up write access to a mount
468 * @mnt: the mount on which to give up write access
470 * Tells the low-level filesystem that we are done performing writes to it and
471 * also allows filesystem to be frozen again. Must be matched with
472 * mnt_want_write() call above.
474 void mnt_drop_write(struct vfsmount
*mnt
)
476 __mnt_drop_write(mnt
);
477 sb_end_write(mnt
->mnt_sb
);
479 EXPORT_SYMBOL_GPL(mnt_drop_write
);
481 void __mnt_drop_write_file(struct file
*file
)
483 __mnt_drop_write(file
->f_path
.mnt
);
486 void mnt_drop_write_file(struct file
*file
)
488 mnt_drop_write(file
->f_path
.mnt
);
490 EXPORT_SYMBOL(mnt_drop_write_file
);
492 static int mnt_make_readonly(struct mount
*mnt
)
497 mnt
->mnt
.mnt_flags
|= MNT_WRITE_HOLD
;
499 * After storing MNT_WRITE_HOLD, we'll read the counters. This store
500 * should be visible before we do.
505 * With writers on hold, if this value is zero, then there are
506 * definitely no active writers (although held writers may subsequently
507 * increment the count, they'll have to wait, and decrement it after
508 * seeing MNT_READONLY).
510 * It is OK to have counter incremented on one CPU and decremented on
511 * another: the sum will add up correctly. The danger would be when we
512 * sum up each counter, if we read a counter before it is incremented,
513 * but then read another CPU's count which it has been subsequently
514 * decremented from -- we would see more decrements than we should.
515 * MNT_WRITE_HOLD protects against this scenario, because
516 * mnt_want_write first increments count, then smp_mb, then spins on
517 * MNT_WRITE_HOLD, so it can't be decremented by another CPU while
518 * we're counting up here.
520 if (mnt_get_writers(mnt
) > 0)
523 mnt
->mnt
.mnt_flags
|= MNT_READONLY
;
525 * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers
526 * that become unheld will see MNT_READONLY.
529 mnt
->mnt
.mnt_flags
&= ~MNT_WRITE_HOLD
;
534 static void __mnt_unmake_readonly(struct mount
*mnt
)
537 mnt
->mnt
.mnt_flags
&= ~MNT_READONLY
;
541 int sb_prepare_remount_readonly(struct super_block
*sb
)
546 /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */
547 if (atomic_long_read(&sb
->s_remove_count
))
551 list_for_each_entry(mnt
, &sb
->s_mounts
, mnt_instance
) {
552 if (!(mnt
->mnt
.mnt_flags
& MNT_READONLY
)) {
553 mnt
->mnt
.mnt_flags
|= MNT_WRITE_HOLD
;
555 if (mnt_get_writers(mnt
) > 0) {
561 if (!err
&& atomic_long_read(&sb
->s_remove_count
))
565 sb
->s_readonly_remount
= 1;
568 list_for_each_entry(mnt
, &sb
->s_mounts
, mnt_instance
) {
569 if (mnt
->mnt
.mnt_flags
& MNT_WRITE_HOLD
)
570 mnt
->mnt
.mnt_flags
&= ~MNT_WRITE_HOLD
;
577 static void free_vfsmnt(struct mount
*mnt
)
579 kfree_const(mnt
->mnt_devname
);
581 free_percpu(mnt
->mnt_pcp
);
583 kmem_cache_free(mnt_cache
, mnt
);
586 static void delayed_free_vfsmnt(struct rcu_head
*head
)
588 free_vfsmnt(container_of(head
, struct mount
, mnt_rcu
));
591 /* call under rcu_read_lock */
592 int __legitimize_mnt(struct vfsmount
*bastard
, unsigned seq
)
595 if (read_seqretry(&mount_lock
, seq
))
599 mnt
= real_mount(bastard
);
600 mnt_add_count(mnt
, 1);
601 if (likely(!read_seqretry(&mount_lock
, seq
)))
603 if (bastard
->mnt_flags
& MNT_SYNC_UMOUNT
) {
604 mnt_add_count(mnt
, -1);
610 /* call under rcu_read_lock */
611 bool legitimize_mnt(struct vfsmount
*bastard
, unsigned seq
)
613 int res
= __legitimize_mnt(bastard
, seq
);
616 if (unlikely(res
< 0)) {
625 * find the first mount at @dentry on vfsmount @mnt.
626 * call under rcu_read_lock()
628 struct mount
*__lookup_mnt(struct vfsmount
*mnt
, struct dentry
*dentry
)
630 struct hlist_head
*head
= m_hash(mnt
, dentry
);
633 hlist_for_each_entry_rcu(p
, head
, mnt_hash
)
634 if (&p
->mnt_parent
->mnt
== mnt
&& p
->mnt_mountpoint
== dentry
)
640 * find the last mount at @dentry on vfsmount @mnt.
641 * mount_lock must be held.
643 struct mount
*__lookup_mnt_last(struct vfsmount
*mnt
, struct dentry
*dentry
)
645 struct mount
*p
, *res
= NULL
;
646 p
= __lookup_mnt(mnt
, dentry
);
649 if (!(p
->mnt
.mnt_flags
& MNT_UMOUNT
))
651 hlist_for_each_entry_continue(p
, mnt_hash
) {
652 if (&p
->mnt_parent
->mnt
!= mnt
|| p
->mnt_mountpoint
!= dentry
)
654 if (!(p
->mnt
.mnt_flags
& MNT_UMOUNT
))
662 * lookup_mnt - Return the first child mount mounted at path
664 * "First" means first mounted chronologically. If you create the
667 * mount /dev/sda1 /mnt
668 * mount /dev/sda2 /mnt
669 * mount /dev/sda3 /mnt
671 * Then lookup_mnt() on the base /mnt dentry in the root mount will
672 * return successively the root dentry and vfsmount of /dev/sda1, then
673 * /dev/sda2, then /dev/sda3, then NULL.
675 * lookup_mnt takes a reference to the found vfsmount.
677 struct vfsmount
*lookup_mnt(struct path
*path
)
679 struct mount
*child_mnt
;
685 seq
= read_seqbegin(&mount_lock
);
686 child_mnt
= __lookup_mnt(path
->mnt
, path
->dentry
);
687 m
= child_mnt
? &child_mnt
->mnt
: NULL
;
688 } while (!legitimize_mnt(m
, seq
));
694 * __is_local_mountpoint - Test to see if dentry is a mountpoint in the
695 * current mount namespace.
697 * The common case is dentries are not mountpoints at all and that
698 * test is handled inline. For the slow case when we are actually
699 * dealing with a mountpoint of some kind, walk through all of the
700 * mounts in the current mount namespace and test to see if the dentry
703 * The mount_hashtable is not usable in the context because we
704 * need to identify all mounts that may be in the current mount
705 * namespace not just a mount that happens to have some specified
708 bool __is_local_mountpoint(struct dentry
*dentry
)
710 struct mnt_namespace
*ns
= current
->nsproxy
->mnt_ns
;
712 bool is_covered
= false;
714 if (!d_mountpoint(dentry
))
717 down_read(&namespace_sem
);
718 list_for_each_entry(mnt
, &ns
->list
, mnt_list
) {
719 is_covered
= (mnt
->mnt_mountpoint
== dentry
);
723 up_read(&namespace_sem
);
728 static struct mountpoint
*lookup_mountpoint(struct dentry
*dentry
)
730 struct hlist_head
*chain
= mp_hash(dentry
);
731 struct mountpoint
*mp
;
733 hlist_for_each_entry(mp
, chain
, m_hash
) {
734 if (mp
->m_dentry
== dentry
) {
735 /* might be worth a WARN_ON() */
736 if (d_unlinked(dentry
))
737 return ERR_PTR(-ENOENT
);
745 static struct mountpoint
*new_mountpoint(struct dentry
*dentry
)
747 struct hlist_head
*chain
= mp_hash(dentry
);
748 struct mountpoint
*mp
;
751 mp
= kmalloc(sizeof(struct mountpoint
), GFP_KERNEL
);
753 return ERR_PTR(-ENOMEM
);
755 ret
= d_set_mounted(dentry
);
761 mp
->m_dentry
= dentry
;
763 hlist_add_head(&mp
->m_hash
, chain
);
764 INIT_HLIST_HEAD(&mp
->m_list
);
768 static void put_mountpoint(struct mountpoint
*mp
)
770 if (!--mp
->m_count
) {
771 struct dentry
*dentry
= mp
->m_dentry
;
772 BUG_ON(!hlist_empty(&mp
->m_list
));
773 spin_lock(&dentry
->d_lock
);
774 dentry
->d_flags
&= ~DCACHE_MOUNTED
;
775 spin_unlock(&dentry
->d_lock
);
776 hlist_del(&mp
->m_hash
);
781 static inline int check_mnt(struct mount
*mnt
)
783 return mnt
->mnt_ns
== current
->nsproxy
->mnt_ns
;
787 * vfsmount lock must be held for write
789 static void touch_mnt_namespace(struct mnt_namespace
*ns
)
793 wake_up_interruptible(&ns
->poll
);
798 * vfsmount lock must be held for write
800 static void __touch_mnt_namespace(struct mnt_namespace
*ns
)
802 if (ns
&& ns
->event
!= event
) {
804 wake_up_interruptible(&ns
->poll
);
809 * vfsmount lock must be held for write
811 static void unhash_mnt(struct mount
*mnt
)
813 mnt
->mnt_parent
= mnt
;
814 mnt
->mnt_mountpoint
= mnt
->mnt
.mnt_root
;
815 list_del_init(&mnt
->mnt_child
);
816 hlist_del_init_rcu(&mnt
->mnt_hash
);
817 hlist_del_init(&mnt
->mnt_mp_list
);
818 put_mountpoint(mnt
->mnt_mp
);
823 * vfsmount lock must be held for write
825 static void detach_mnt(struct mount
*mnt
, struct path
*old_path
)
827 old_path
->dentry
= mnt
->mnt_mountpoint
;
828 old_path
->mnt
= &mnt
->mnt_parent
->mnt
;
833 * vfsmount lock must be held for write
835 static void umount_mnt(struct mount
*mnt
)
837 /* old mountpoint will be dropped when we can do that */
838 mnt
->mnt_ex_mountpoint
= mnt
->mnt_mountpoint
;
843 * vfsmount lock must be held for write
845 void mnt_set_mountpoint(struct mount
*mnt
,
846 struct mountpoint
*mp
,
847 struct mount
*child_mnt
)
850 mnt_add_count(mnt
, 1); /* essentially, that's mntget */
851 child_mnt
->mnt_mountpoint
= dget(mp
->m_dentry
);
852 child_mnt
->mnt_parent
= mnt
;
853 child_mnt
->mnt_mp
= mp
;
854 hlist_add_head(&child_mnt
->mnt_mp_list
, &mp
->m_list
);
858 * vfsmount lock must be held for write
860 static void attach_mnt(struct mount
*mnt
,
861 struct mount
*parent
,
862 struct mountpoint
*mp
)
864 mnt_set_mountpoint(parent
, mp
, mnt
);
865 hlist_add_head_rcu(&mnt
->mnt_hash
, m_hash(&parent
->mnt
, mp
->m_dentry
));
866 list_add_tail(&mnt
->mnt_child
, &parent
->mnt_mounts
);
869 static void attach_shadowed(struct mount
*mnt
,
870 struct mount
*parent
,
871 struct mount
*shadows
)
874 hlist_add_behind_rcu(&mnt
->mnt_hash
, &shadows
->mnt_hash
);
875 list_add(&mnt
->mnt_child
, &shadows
->mnt_child
);
877 hlist_add_head_rcu(&mnt
->mnt_hash
,
878 m_hash(&parent
->mnt
, mnt
->mnt_mountpoint
));
879 list_add_tail(&mnt
->mnt_child
, &parent
->mnt_mounts
);
884 * vfsmount lock must be held for write
886 static void commit_tree(struct mount
*mnt
, struct mount
*shadows
)
888 struct mount
*parent
= mnt
->mnt_parent
;
891 struct mnt_namespace
*n
= parent
->mnt_ns
;
893 BUG_ON(parent
== mnt
);
895 list_add_tail(&head
, &mnt
->mnt_list
);
896 list_for_each_entry(m
, &head
, mnt_list
)
899 list_splice(&head
, n
->list
.prev
);
901 n
->mounts
+= n
->pending_mounts
;
902 n
->pending_mounts
= 0;
904 attach_shadowed(mnt
, parent
, shadows
);
905 touch_mnt_namespace(n
);
908 static struct mount
*next_mnt(struct mount
*p
, struct mount
*root
)
910 struct list_head
*next
= p
->mnt_mounts
.next
;
911 if (next
== &p
->mnt_mounts
) {
915 next
= p
->mnt_child
.next
;
916 if (next
!= &p
->mnt_parent
->mnt_mounts
)
921 return list_entry(next
, struct mount
, mnt_child
);
924 static struct mount
*skip_mnt_tree(struct mount
*p
)
926 struct list_head
*prev
= p
->mnt_mounts
.prev
;
927 while (prev
!= &p
->mnt_mounts
) {
928 p
= list_entry(prev
, struct mount
, mnt_child
);
929 prev
= p
->mnt_mounts
.prev
;
935 vfs_kern_mount(struct file_system_type
*type
, int flags
, const char *name
, void *data
)
941 return ERR_PTR(-ENODEV
);
943 mnt
= alloc_vfsmnt(name
);
945 return ERR_PTR(-ENOMEM
);
947 if (flags
& MS_KERNMOUNT
)
948 mnt
->mnt
.mnt_flags
= MNT_INTERNAL
;
950 root
= mount_fs(type
, flags
, name
, data
);
954 return ERR_CAST(root
);
957 mnt
->mnt
.mnt_root
= root
;
958 mnt
->mnt
.mnt_sb
= root
->d_sb
;
959 mnt
->mnt_mountpoint
= mnt
->mnt
.mnt_root
;
960 mnt
->mnt_parent
= mnt
;
962 list_add_tail(&mnt
->mnt_instance
, &root
->d_sb
->s_mounts
);
966 EXPORT_SYMBOL_GPL(vfs_kern_mount
);
968 static struct mount
*clone_mnt(struct mount
*old
, struct dentry
*root
,
971 struct super_block
*sb
= old
->mnt
.mnt_sb
;
975 mnt
= alloc_vfsmnt(old
->mnt_devname
);
977 return ERR_PTR(-ENOMEM
);
979 if (flag
& (CL_SLAVE
| CL_PRIVATE
| CL_SHARED_TO_SLAVE
))
980 mnt
->mnt_group_id
= 0; /* not a peer of original */
982 mnt
->mnt_group_id
= old
->mnt_group_id
;
984 if ((flag
& CL_MAKE_SHARED
) && !mnt
->mnt_group_id
) {
985 err
= mnt_alloc_group_id(mnt
);
990 mnt
->mnt
.mnt_flags
= old
->mnt
.mnt_flags
& ~(MNT_WRITE_HOLD
|MNT_MARKED
);
991 /* Don't allow unprivileged users to change mount flags */
992 if (flag
& CL_UNPRIVILEGED
) {
993 mnt
->mnt
.mnt_flags
|= MNT_LOCK_ATIME
;
995 if (mnt
->mnt
.mnt_flags
& MNT_READONLY
)
996 mnt
->mnt
.mnt_flags
|= MNT_LOCK_READONLY
;
998 if (mnt
->mnt
.mnt_flags
& MNT_NODEV
)
999 mnt
->mnt
.mnt_flags
|= MNT_LOCK_NODEV
;
1001 if (mnt
->mnt
.mnt_flags
& MNT_NOSUID
)
1002 mnt
->mnt
.mnt_flags
|= MNT_LOCK_NOSUID
;
1004 if (mnt
->mnt
.mnt_flags
& MNT_NOEXEC
)
1005 mnt
->mnt
.mnt_flags
|= MNT_LOCK_NOEXEC
;
1008 /* Don't allow unprivileged users to reveal what is under a mount */
1009 if ((flag
& CL_UNPRIVILEGED
) &&
1010 (!(flag
& CL_EXPIRE
) || list_empty(&old
->mnt_expire
)))
1011 mnt
->mnt
.mnt_flags
|= MNT_LOCKED
;
1013 atomic_inc(&sb
->s_active
);
1014 mnt
->mnt
.mnt_sb
= sb
;
1015 mnt
->mnt
.mnt_root
= dget(root
);
1016 mnt
->mnt_mountpoint
= mnt
->mnt
.mnt_root
;
1017 mnt
->mnt_parent
= mnt
;
1019 list_add_tail(&mnt
->mnt_instance
, &sb
->s_mounts
);
1020 unlock_mount_hash();
1022 if ((flag
& CL_SLAVE
) ||
1023 ((flag
& CL_SHARED_TO_SLAVE
) && IS_MNT_SHARED(old
))) {
1024 list_add(&mnt
->mnt_slave
, &old
->mnt_slave_list
);
1025 mnt
->mnt_master
= old
;
1026 CLEAR_MNT_SHARED(mnt
);
1027 } else if (!(flag
& CL_PRIVATE
)) {
1028 if ((flag
& CL_MAKE_SHARED
) || IS_MNT_SHARED(old
))
1029 list_add(&mnt
->mnt_share
, &old
->mnt_share
);
1030 if (IS_MNT_SLAVE(old
))
1031 list_add(&mnt
->mnt_slave
, &old
->mnt_slave
);
1032 mnt
->mnt_master
= old
->mnt_master
;
1034 if (flag
& CL_MAKE_SHARED
)
1035 set_mnt_shared(mnt
);
1037 /* stick the duplicate mount on the same expiry list
1038 * as the original if that was on one */
1039 if (flag
& CL_EXPIRE
) {
1040 if (!list_empty(&old
->mnt_expire
))
1041 list_add(&mnt
->mnt_expire
, &old
->mnt_expire
);
1049 return ERR_PTR(err
);
1052 static void cleanup_mnt(struct mount
*mnt
)
1055 * This probably indicates that somebody messed
1056 * up a mnt_want/drop_write() pair. If this
1057 * happens, the filesystem was probably unable
1058 * to make r/w->r/o transitions.
1061 * The locking used to deal with mnt_count decrement provides barriers,
1062 * so mnt_get_writers() below is safe.
1064 WARN_ON(mnt_get_writers(mnt
));
1065 if (unlikely(mnt
->mnt_pins
.first
))
1067 fsnotify_vfsmount_delete(&mnt
->mnt
);
1068 dput(mnt
->mnt
.mnt_root
);
1069 deactivate_super(mnt
->mnt
.mnt_sb
);
1071 call_rcu(&mnt
->mnt_rcu
, delayed_free_vfsmnt
);
1074 static void __cleanup_mnt(struct rcu_head
*head
)
1076 cleanup_mnt(container_of(head
, struct mount
, mnt_rcu
));
1079 static LLIST_HEAD(delayed_mntput_list
);
1080 static void delayed_mntput(struct work_struct
*unused
)
1082 struct llist_node
*node
= llist_del_all(&delayed_mntput_list
);
1083 struct llist_node
*next
;
1085 for (; node
; node
= next
) {
1086 next
= llist_next(node
);
1087 cleanup_mnt(llist_entry(node
, struct mount
, mnt_llist
));
1090 static DECLARE_DELAYED_WORK(delayed_mntput_work
, delayed_mntput
);
1092 static void mntput_no_expire(struct mount
*mnt
)
1095 mnt_add_count(mnt
, -1);
1096 if (likely(mnt
->mnt_ns
)) { /* shouldn't be the last one */
1101 if (mnt_get_count(mnt
)) {
1103 unlock_mount_hash();
1106 if (unlikely(mnt
->mnt
.mnt_flags
& MNT_DOOMED
)) {
1108 unlock_mount_hash();
1111 mnt
->mnt
.mnt_flags
|= MNT_DOOMED
;
1114 list_del(&mnt
->mnt_instance
);
1116 if (unlikely(!list_empty(&mnt
->mnt_mounts
))) {
1117 struct mount
*p
, *tmp
;
1118 list_for_each_entry_safe(p
, tmp
, &mnt
->mnt_mounts
, mnt_child
) {
1122 unlock_mount_hash();
1124 if (likely(!(mnt
->mnt
.mnt_flags
& MNT_INTERNAL
))) {
1125 struct task_struct
*task
= current
;
1126 if (likely(!(task
->flags
& PF_KTHREAD
))) {
1127 init_task_work(&mnt
->mnt_rcu
, __cleanup_mnt
);
1128 if (!task_work_add(task
, &mnt
->mnt_rcu
, true))
1131 if (llist_add(&mnt
->mnt_llist
, &delayed_mntput_list
))
1132 schedule_delayed_work(&delayed_mntput_work
, 1);
1138 void mntput(struct vfsmount
*mnt
)
1141 struct mount
*m
= real_mount(mnt
);
1142 /* avoid cacheline pingpong, hope gcc doesn't get "smart" */
1143 if (unlikely(m
->mnt_expiry_mark
))
1144 m
->mnt_expiry_mark
= 0;
1145 mntput_no_expire(m
);
1148 EXPORT_SYMBOL(mntput
);
1150 struct vfsmount
*mntget(struct vfsmount
*mnt
)
1153 mnt_add_count(real_mount(mnt
), 1);
1156 EXPORT_SYMBOL(mntget
);
1158 struct vfsmount
*mnt_clone_internal(struct path
*path
)
1161 p
= clone_mnt(real_mount(path
->mnt
), path
->dentry
, CL_PRIVATE
);
1164 p
->mnt
.mnt_flags
|= MNT_INTERNAL
;
1168 static inline void mangle(struct seq_file
*m
, const char *s
)
1170 seq_escape(m
, s
, " \t\n\\");
1174 * Simple .show_options callback for filesystems which don't want to
1175 * implement more complex mount option showing.
1177 * See also save_mount_options().
1179 int generic_show_options(struct seq_file
*m
, struct dentry
*root
)
1181 const char *options
;
1184 options
= rcu_dereference(root
->d_sb
->s_options
);
1186 if (options
!= NULL
&& options
[0]) {
1194 EXPORT_SYMBOL(generic_show_options
);
1197 * If filesystem uses generic_show_options(), this function should be
1198 * called from the fill_super() callback.
1200 * The .remount_fs callback usually needs to be handled in a special
1201 * way, to make sure, that previous options are not overwritten if the
1204 * Also note, that if the filesystem's .remount_fs function doesn't
1205 * reset all options to their default value, but changes only newly
1206 * given options, then the displayed options will not reflect reality
1209 void save_mount_options(struct super_block
*sb
, char *options
)
1211 BUG_ON(sb
->s_options
);
1212 rcu_assign_pointer(sb
->s_options
, kstrdup(options
, GFP_KERNEL
));
1214 EXPORT_SYMBOL(save_mount_options
);
1216 void replace_mount_options(struct super_block
*sb
, char *options
)
1218 char *old
= sb
->s_options
;
1219 rcu_assign_pointer(sb
->s_options
, options
);
1225 EXPORT_SYMBOL(replace_mount_options
);
1227 #ifdef CONFIG_PROC_FS
1228 /* iterator; we want it to have access to namespace_sem, thus here... */
1229 static void *m_start(struct seq_file
*m
, loff_t
*pos
)
1231 struct proc_mounts
*p
= m
->private;
1233 down_read(&namespace_sem
);
1234 if (p
->cached_event
== p
->ns
->event
) {
1235 void *v
= p
->cached_mount
;
1236 if (*pos
== p
->cached_index
)
1238 if (*pos
== p
->cached_index
+ 1) {
1239 v
= seq_list_next(v
, &p
->ns
->list
, &p
->cached_index
);
1240 return p
->cached_mount
= v
;
1244 p
->cached_event
= p
->ns
->event
;
1245 p
->cached_mount
= seq_list_start(&p
->ns
->list
, *pos
);
1246 p
->cached_index
= *pos
;
1247 return p
->cached_mount
;
1250 static void *m_next(struct seq_file
*m
, void *v
, loff_t
*pos
)
1252 struct proc_mounts
*p
= m
->private;
1254 p
->cached_mount
= seq_list_next(v
, &p
->ns
->list
, pos
);
1255 p
->cached_index
= *pos
;
1256 return p
->cached_mount
;
1259 static void m_stop(struct seq_file
*m
, void *v
)
1261 up_read(&namespace_sem
);
1264 static int m_show(struct seq_file
*m
, void *v
)
1266 struct proc_mounts
*p
= m
->private;
1267 struct mount
*r
= list_entry(v
, struct mount
, mnt_list
);
1268 return p
->show(m
, &r
->mnt
);
1271 const struct seq_operations mounts_op
= {
1277 #endif /* CONFIG_PROC_FS */
1280 * may_umount_tree - check if a mount tree is busy
1281 * @mnt: root of mount tree
1283 * This is called to check if a tree of mounts has any
1284 * open files, pwds, chroots or sub mounts that are
1287 int may_umount_tree(struct vfsmount
*m
)
1289 struct mount
*mnt
= real_mount(m
);
1290 int actual_refs
= 0;
1291 int minimum_refs
= 0;
1295 /* write lock needed for mnt_get_count */
1297 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
)) {
1298 actual_refs
+= mnt_get_count(p
);
1301 unlock_mount_hash();
1303 if (actual_refs
> minimum_refs
)
1309 EXPORT_SYMBOL(may_umount_tree
);
1312 * may_umount - check if a mount point is busy
1313 * @mnt: root of mount
1315 * This is called to check if a mount point has any
1316 * open files, pwds, chroots or sub mounts. If the
1317 * mount has sub mounts this will return busy
1318 * regardless of whether the sub mounts are busy.
1320 * Doesn't take quota and stuff into account. IOW, in some cases it will
1321 * give false negatives. The main reason why it's here is that we need
1322 * a non-destructive way to look for easily umountable filesystems.
1324 int may_umount(struct vfsmount
*mnt
)
1327 down_read(&namespace_sem
);
1329 if (propagate_mount_busy(real_mount(mnt
), 2))
1331 unlock_mount_hash();
1332 up_read(&namespace_sem
);
1336 EXPORT_SYMBOL(may_umount
);
1338 static HLIST_HEAD(unmounted
); /* protected by namespace_sem */
1340 static void namespace_unlock(void)
1342 struct hlist_head head
;
1344 hlist_move_list(&unmounted
, &head
);
1346 up_write(&namespace_sem
);
1348 if (likely(hlist_empty(&head
)))
1353 group_pin_kill(&head
);
1356 static inline void namespace_lock(void)
1358 down_write(&namespace_sem
);
1361 enum umount_tree_flags
{
1363 UMOUNT_PROPAGATE
= 2,
1364 UMOUNT_CONNECTED
= 4,
1367 static bool disconnect_mount(struct mount
*mnt
, enum umount_tree_flags how
)
1369 /* Leaving mounts connected is only valid for lazy umounts */
1370 if (how
& UMOUNT_SYNC
)
1373 /* A mount without a parent has nothing to be connected to */
1374 if (!mnt_has_parent(mnt
))
1377 /* Because the reference counting rules change when mounts are
1378 * unmounted and connected, umounted mounts may not be
1379 * connected to mounted mounts.
1381 if (!(mnt
->mnt_parent
->mnt
.mnt_flags
& MNT_UMOUNT
))
1384 /* Has it been requested that the mount remain connected? */
1385 if (how
& UMOUNT_CONNECTED
)
1388 /* Is the mount locked such that it needs to remain connected? */
1389 if (IS_MNT_LOCKED(mnt
))
1392 /* By default disconnect the mount */
1397 * mount_lock must be held
1398 * namespace_sem must be held for write
1400 static void umount_tree(struct mount
*mnt
, enum umount_tree_flags how
)
1402 LIST_HEAD(tmp_list
);
1405 if (how
& UMOUNT_PROPAGATE
)
1406 propagate_mount_unlock(mnt
);
1408 /* Gather the mounts to umount */
1409 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
)) {
1410 p
->mnt
.mnt_flags
|= MNT_UMOUNT
;
1411 list_move(&p
->mnt_list
, &tmp_list
);
1414 /* Hide the mounts from mnt_mounts */
1415 list_for_each_entry(p
, &tmp_list
, mnt_list
) {
1416 list_del_init(&p
->mnt_child
);
1419 /* Add propogated mounts to the tmp_list */
1420 if (how
& UMOUNT_PROPAGATE
)
1421 propagate_umount(&tmp_list
);
1423 while (!list_empty(&tmp_list
)) {
1424 struct mnt_namespace
*ns
;
1426 p
= list_first_entry(&tmp_list
, struct mount
, mnt_list
);
1427 list_del_init(&p
->mnt_expire
);
1428 list_del_init(&p
->mnt_list
);
1432 __touch_mnt_namespace(ns
);
1435 if (how
& UMOUNT_SYNC
)
1436 p
->mnt
.mnt_flags
|= MNT_SYNC_UMOUNT
;
1438 disconnect
= disconnect_mount(p
, how
);
1440 pin_insert_group(&p
->mnt_umount
, &p
->mnt_parent
->mnt
,
1441 disconnect
? &unmounted
: NULL
);
1442 if (mnt_has_parent(p
)) {
1443 mnt_add_count(p
->mnt_parent
, -1);
1445 /* Don't forget about p */
1446 list_add_tail(&p
->mnt_child
, &p
->mnt_parent
->mnt_mounts
);
1451 change_mnt_propagation(p
, MS_PRIVATE
);
1455 static void shrink_submounts(struct mount
*mnt
);
1457 static int do_umount(struct mount
*mnt
, int flags
)
1459 struct super_block
*sb
= mnt
->mnt
.mnt_sb
;
1462 retval
= security_sb_umount(&mnt
->mnt
, flags
);
1467 * Allow userspace to request a mountpoint be expired rather than
1468 * unmounting unconditionally. Unmount only happens if:
1469 * (1) the mark is already set (the mark is cleared by mntput())
1470 * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
1472 if (flags
& MNT_EXPIRE
) {
1473 if (&mnt
->mnt
== current
->fs
->root
.mnt
||
1474 flags
& (MNT_FORCE
| MNT_DETACH
))
1478 * probably don't strictly need the lock here if we examined
1479 * all race cases, but it's a slowpath.
1482 if (mnt_get_count(mnt
) != 2) {
1483 unlock_mount_hash();
1486 unlock_mount_hash();
1488 if (!xchg(&mnt
->mnt_expiry_mark
, 1))
1493 * If we may have to abort operations to get out of this
1494 * mount, and they will themselves hold resources we must
1495 * allow the fs to do things. In the Unix tradition of
1496 * 'Gee thats tricky lets do it in userspace' the umount_begin
1497 * might fail to complete on the first run through as other tasks
1498 * must return, and the like. Thats for the mount program to worry
1499 * about for the moment.
1502 if (flags
& MNT_FORCE
&& sb
->s_op
->umount_begin
) {
1503 sb
->s_op
->umount_begin(sb
);
1507 * No sense to grab the lock for this test, but test itself looks
1508 * somewhat bogus. Suggestions for better replacement?
1509 * Ho-hum... In principle, we might treat that as umount + switch
1510 * to rootfs. GC would eventually take care of the old vfsmount.
1511 * Actually it makes sense, especially if rootfs would contain a
1512 * /reboot - static binary that would close all descriptors and
1513 * call reboot(9). Then init(8) could umount root and exec /reboot.
1515 if (&mnt
->mnt
== current
->fs
->root
.mnt
&& !(flags
& MNT_DETACH
)) {
1517 * Special case for "unmounting" root ...
1518 * we just try to remount it readonly.
1520 if (!capable(CAP_SYS_ADMIN
))
1522 down_write(&sb
->s_umount
);
1523 if (!(sb
->s_flags
& MS_RDONLY
))
1524 retval
= do_remount_sb(sb
, MS_RDONLY
, NULL
, 0);
1525 up_write(&sb
->s_umount
);
1533 if (flags
& MNT_DETACH
) {
1534 if (!list_empty(&mnt
->mnt_list
))
1535 umount_tree(mnt
, UMOUNT_PROPAGATE
);
1538 shrink_submounts(mnt
);
1540 if (!propagate_mount_busy(mnt
, 2)) {
1541 if (!list_empty(&mnt
->mnt_list
))
1542 umount_tree(mnt
, UMOUNT_PROPAGATE
|UMOUNT_SYNC
);
1546 unlock_mount_hash();
1552 * __detach_mounts - lazily unmount all mounts on the specified dentry
1554 * During unlink, rmdir, and d_drop it is possible to loose the path
1555 * to an existing mountpoint, and wind up leaking the mount.
1556 * detach_mounts allows lazily unmounting those mounts instead of
1559 * The caller may hold dentry->d_inode->i_mutex.
1561 void __detach_mounts(struct dentry
*dentry
)
1563 struct mountpoint
*mp
;
1567 mp
= lookup_mountpoint(dentry
);
1568 if (IS_ERR_OR_NULL(mp
))
1573 while (!hlist_empty(&mp
->m_list
)) {
1574 mnt
= hlist_entry(mp
->m_list
.first
, struct mount
, mnt_mp_list
);
1575 if (mnt
->mnt
.mnt_flags
& MNT_UMOUNT
) {
1576 hlist_add_head(&mnt
->mnt_umount
.s_list
, &unmounted
);
1579 else umount_tree(mnt
, UMOUNT_CONNECTED
);
1581 unlock_mount_hash();
1588 * Is the caller allowed to modify his namespace?
1590 static inline bool may_mount(void)
1592 return ns_capable(current
->nsproxy
->mnt_ns
->user_ns
, CAP_SYS_ADMIN
);
1595 static inline bool may_mandlock(void)
1597 #ifndef CONFIG_MANDATORY_FILE_LOCKING
1600 return capable(CAP_SYS_ADMIN
);
1604 * Now umount can handle mount points as well as block devices.
1605 * This is important for filesystems which use unnamed block devices.
1607 * We now support a flag for forced unmount like the other 'big iron'
1608 * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
1611 SYSCALL_DEFINE2(umount
, char __user
*, name
, int, flags
)
1616 int lookup_flags
= 0;
1618 if (flags
& ~(MNT_FORCE
| MNT_DETACH
| MNT_EXPIRE
| UMOUNT_NOFOLLOW
))
1624 if (!(flags
& UMOUNT_NOFOLLOW
))
1625 lookup_flags
|= LOOKUP_FOLLOW
;
1627 retval
= user_path_mountpoint_at(AT_FDCWD
, name
, lookup_flags
, &path
);
1630 mnt
= real_mount(path
.mnt
);
1632 if (path
.dentry
!= path
.mnt
->mnt_root
)
1634 if (!check_mnt(mnt
))
1636 if (mnt
->mnt
.mnt_flags
& MNT_LOCKED
)
1639 if (flags
& MNT_FORCE
&& !capable(CAP_SYS_ADMIN
))
1642 retval
= do_umount(mnt
, flags
);
1644 /* we mustn't call path_put() as that would clear mnt_expiry_mark */
1646 mntput_no_expire(mnt
);
1651 #ifdef __ARCH_WANT_SYS_OLDUMOUNT
1654 * The 2.0 compatible umount. No flags.
1656 SYSCALL_DEFINE1(oldumount
, char __user
*, name
)
1658 return sys_umount(name
, 0);
1663 static bool is_mnt_ns_file(struct dentry
*dentry
)
1665 /* Is this a proxy for a mount namespace? */
1666 return dentry
->d_op
== &ns_dentry_operations
&&
1667 dentry
->d_fsdata
== &mntns_operations
;
1670 struct mnt_namespace
*to_mnt_ns(struct ns_common
*ns
)
1672 return container_of(ns
, struct mnt_namespace
, ns
);
1675 static bool mnt_ns_loop(struct dentry
*dentry
)
1677 /* Could bind mounting the mount namespace inode cause a
1678 * mount namespace loop?
1680 struct mnt_namespace
*mnt_ns
;
1681 if (!is_mnt_ns_file(dentry
))
1684 mnt_ns
= to_mnt_ns(get_proc_ns(dentry
->d_inode
));
1685 return current
->nsproxy
->mnt_ns
->seq
>= mnt_ns
->seq
;
1688 struct mount
*copy_tree(struct mount
*mnt
, struct dentry
*dentry
,
1691 struct mount
*res
, *p
, *q
, *r
, *parent
;
1693 if (!(flag
& CL_COPY_UNBINDABLE
) && IS_MNT_UNBINDABLE(mnt
))
1694 return ERR_PTR(-EINVAL
);
1696 if (!(flag
& CL_COPY_MNT_NS_FILE
) && is_mnt_ns_file(dentry
))
1697 return ERR_PTR(-EINVAL
);
1699 res
= q
= clone_mnt(mnt
, dentry
, flag
);
1703 q
->mnt_mountpoint
= mnt
->mnt_mountpoint
;
1706 list_for_each_entry(r
, &mnt
->mnt_mounts
, mnt_child
) {
1708 if (!is_subdir(r
->mnt_mountpoint
, dentry
))
1711 for (s
= r
; s
; s
= next_mnt(s
, r
)) {
1712 struct mount
*t
= NULL
;
1713 if (!(flag
& CL_COPY_UNBINDABLE
) &&
1714 IS_MNT_UNBINDABLE(s
)) {
1715 s
= skip_mnt_tree(s
);
1718 if (!(flag
& CL_COPY_MNT_NS_FILE
) &&
1719 is_mnt_ns_file(s
->mnt
.mnt_root
)) {
1720 s
= skip_mnt_tree(s
);
1723 while (p
!= s
->mnt_parent
) {
1729 q
= clone_mnt(p
, p
->mnt
.mnt_root
, flag
);
1733 list_add_tail(&q
->mnt_list
, &res
->mnt_list
);
1734 mnt_set_mountpoint(parent
, p
->mnt_mp
, q
);
1735 if (!list_empty(&parent
->mnt_mounts
)) {
1736 t
= list_last_entry(&parent
->mnt_mounts
,
1737 struct mount
, mnt_child
);
1738 if (t
->mnt_mp
!= p
->mnt_mp
)
1741 attach_shadowed(q
, parent
, t
);
1742 unlock_mount_hash();
1749 umount_tree(res
, UMOUNT_SYNC
);
1750 unlock_mount_hash();
1755 /* Caller should check returned pointer for errors */
1757 struct vfsmount
*collect_mounts(struct path
*path
)
1761 if (!check_mnt(real_mount(path
->mnt
)))
1762 tree
= ERR_PTR(-EINVAL
);
1764 tree
= copy_tree(real_mount(path
->mnt
), path
->dentry
,
1765 CL_COPY_ALL
| CL_PRIVATE
);
1768 return ERR_CAST(tree
);
1772 void drop_collected_mounts(struct vfsmount
*mnt
)
1776 umount_tree(real_mount(mnt
), UMOUNT_SYNC
);
1777 unlock_mount_hash();
1782 * clone_private_mount - create a private clone of a path
1784 * This creates a new vfsmount, which will be the clone of @path. The new will
1785 * not be attached anywhere in the namespace and will be private (i.e. changes
1786 * to the originating mount won't be propagated into this).
1788 * Release with mntput().
1790 struct vfsmount
*clone_private_mount(struct path
*path
)
1792 struct mount
*old_mnt
= real_mount(path
->mnt
);
1793 struct mount
*new_mnt
;
1795 if (IS_MNT_UNBINDABLE(old_mnt
))
1796 return ERR_PTR(-EINVAL
);
1798 new_mnt
= clone_mnt(old_mnt
, path
->dentry
, CL_PRIVATE
);
1799 if (IS_ERR(new_mnt
))
1800 return ERR_CAST(new_mnt
);
1802 return &new_mnt
->mnt
;
1804 EXPORT_SYMBOL_GPL(clone_private_mount
);
1806 int iterate_mounts(int (*f
)(struct vfsmount
*, void *), void *arg
,
1807 struct vfsmount
*root
)
1810 int res
= f(root
, arg
);
1813 list_for_each_entry(mnt
, &real_mount(root
)->mnt_list
, mnt_list
) {
1814 res
= f(&mnt
->mnt
, arg
);
1821 static void cleanup_group_ids(struct mount
*mnt
, struct mount
*end
)
1825 for (p
= mnt
; p
!= end
; p
= next_mnt(p
, mnt
)) {
1826 if (p
->mnt_group_id
&& !IS_MNT_SHARED(p
))
1827 mnt_release_group_id(p
);
1831 static int invent_group_ids(struct mount
*mnt
, bool recurse
)
1835 for (p
= mnt
; p
; p
= recurse
? next_mnt(p
, mnt
) : NULL
) {
1836 if (!p
->mnt_group_id
&& !IS_MNT_SHARED(p
)) {
1837 int err
= mnt_alloc_group_id(p
);
1839 cleanup_group_ids(mnt
, p
);
1848 int count_mounts(struct mnt_namespace
*ns
, struct mount
*mnt
)
1850 unsigned int max
= READ_ONCE(sysctl_mount_max
);
1851 unsigned int mounts
= 0, old
, pending
, sum
;
1854 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
))
1858 pending
= ns
->pending_mounts
;
1859 sum
= old
+ pending
;
1863 (mounts
> (max
- sum
)))
1866 ns
->pending_mounts
= pending
+ mounts
;
1871 * @source_mnt : mount tree to be attached
1872 * @nd : place the mount tree @source_mnt is attached
1873 * @parent_nd : if non-null, detach the source_mnt from its parent and
1874 * store the parent mount and mountpoint dentry.
1875 * (done when source_mnt is moved)
1877 * NOTE: in the table below explains the semantics when a source mount
1878 * of a given type is attached to a destination mount of a given type.
1879 * ---------------------------------------------------------------------------
1880 * | BIND MOUNT OPERATION |
1881 * |**************************************************************************
1882 * | source-->| shared | private | slave | unbindable |
1886 * |**************************************************************************
1887 * | shared | shared (++) | shared (+) | shared(+++)| invalid |
1889 * |non-shared| shared (+) | private | slave (*) | invalid |
1890 * ***************************************************************************
1891 * A bind operation clones the source mount and mounts the clone on the
1892 * destination mount.
1894 * (++) the cloned mount is propagated to all the mounts in the propagation
1895 * tree of the destination mount and the cloned mount is added to
1896 * the peer group of the source mount.
1897 * (+) the cloned mount is created under the destination mount and is marked
1898 * as shared. The cloned mount is added to the peer group of the source
1900 * (+++) the mount is propagated to all the mounts in the propagation tree
1901 * of the destination mount and the cloned mount is made slave
1902 * of the same master as that of the source mount. The cloned mount
1903 * is marked as 'shared and slave'.
1904 * (*) the cloned mount is made a slave of the same master as that of the
1907 * ---------------------------------------------------------------------------
1908 * | MOVE MOUNT OPERATION |
1909 * |**************************************************************************
1910 * | source-->| shared | private | slave | unbindable |
1914 * |**************************************************************************
1915 * | shared | shared (+) | shared (+) | shared(+++) | invalid |
1917 * |non-shared| shared (+*) | private | slave (*) | unbindable |
1918 * ***************************************************************************
1920 * (+) the mount is moved to the destination. And is then propagated to
1921 * all the mounts in the propagation tree of the destination mount.
1922 * (+*) the mount is moved to the destination.
1923 * (+++) the mount is moved to the destination and is then propagated to
1924 * all the mounts belonging to the destination mount's propagation tree.
1925 * the mount is marked as 'shared and slave'.
1926 * (*) the mount continues to be a slave at the new location.
1928 * if the source mount is a tree, the operations explained above is
1929 * applied to each mount in the tree.
1930 * Must be called without spinlocks held, since this function can sleep
1933 static int attach_recursive_mnt(struct mount
*source_mnt
,
1934 struct mount
*dest_mnt
,
1935 struct mountpoint
*dest_mp
,
1936 struct path
*parent_path
)
1938 HLIST_HEAD(tree_list
);
1939 struct mnt_namespace
*ns
= dest_mnt
->mnt_ns
;
1940 struct mount
*child
, *p
;
1941 struct hlist_node
*n
;
1944 /* Is there space to add these mounts to the mount namespace? */
1946 err
= count_mounts(ns
, source_mnt
);
1951 if (IS_MNT_SHARED(dest_mnt
)) {
1952 err
= invent_group_ids(source_mnt
, true);
1955 err
= propagate_mnt(dest_mnt
, dest_mp
, source_mnt
, &tree_list
);
1958 goto out_cleanup_ids
;
1959 for (p
= source_mnt
; p
; p
= next_mnt(p
, source_mnt
))
1965 detach_mnt(source_mnt
, parent_path
);
1966 attach_mnt(source_mnt
, dest_mnt
, dest_mp
);
1967 touch_mnt_namespace(source_mnt
->mnt_ns
);
1969 mnt_set_mountpoint(dest_mnt
, dest_mp
, source_mnt
);
1970 commit_tree(source_mnt
, NULL
);
1973 hlist_for_each_entry_safe(child
, n
, &tree_list
, mnt_hash
) {
1975 hlist_del_init(&child
->mnt_hash
);
1976 q
= __lookup_mnt_last(&child
->mnt_parent
->mnt
,
1977 child
->mnt_mountpoint
);
1978 commit_tree(child
, q
);
1980 unlock_mount_hash();
1985 while (!hlist_empty(&tree_list
)) {
1986 child
= hlist_entry(tree_list
.first
, struct mount
, mnt_hash
);
1987 child
->mnt_parent
->mnt_ns
->pending_mounts
= 0;
1988 umount_tree(child
, UMOUNT_SYNC
);
1990 unlock_mount_hash();
1991 cleanup_group_ids(source_mnt
, NULL
);
1993 ns
->pending_mounts
= 0;
1997 static struct mountpoint
*lock_mount(struct path
*path
)
1999 struct vfsmount
*mnt
;
2000 struct dentry
*dentry
= path
->dentry
;
2002 inode_lock(dentry
->d_inode
);
2003 if (unlikely(cant_mount(dentry
))) {
2004 inode_unlock(dentry
->d_inode
);
2005 return ERR_PTR(-ENOENT
);
2008 mnt
= lookup_mnt(path
);
2010 struct mountpoint
*mp
= lookup_mountpoint(dentry
);
2012 mp
= new_mountpoint(dentry
);
2015 inode_unlock(dentry
->d_inode
);
2021 inode_unlock(path
->dentry
->d_inode
);
2024 dentry
= path
->dentry
= dget(mnt
->mnt_root
);
2028 static void unlock_mount(struct mountpoint
*where
)
2030 struct dentry
*dentry
= where
->m_dentry
;
2031 put_mountpoint(where
);
2033 inode_unlock(dentry
->d_inode
);
2036 static int graft_tree(struct mount
*mnt
, struct mount
*p
, struct mountpoint
*mp
)
2038 if (mnt
->mnt
.mnt_sb
->s_flags
& MS_NOUSER
)
2041 if (d_is_dir(mp
->m_dentry
) !=
2042 d_is_dir(mnt
->mnt
.mnt_root
))
2045 return attach_recursive_mnt(mnt
, p
, mp
, NULL
);
2049 * Sanity check the flags to change_mnt_propagation.
2052 static int flags_to_propagation_type(int flags
)
2054 int type
= flags
& ~(MS_REC
| MS_SILENT
);
2056 /* Fail if any non-propagation flags are set */
2057 if (type
& ~(MS_SHARED
| MS_PRIVATE
| MS_SLAVE
| MS_UNBINDABLE
))
2059 /* Only one propagation flag should be set */
2060 if (!is_power_of_2(type
))
2066 * recursively change the type of the mountpoint.
2068 static int do_change_type(struct path
*path
, int flag
)
2071 struct mount
*mnt
= real_mount(path
->mnt
);
2072 int recurse
= flag
& MS_REC
;
2076 if (path
->dentry
!= path
->mnt
->mnt_root
)
2079 type
= flags_to_propagation_type(flag
);
2084 if (type
== MS_SHARED
) {
2085 err
= invent_group_ids(mnt
, recurse
);
2091 for (m
= mnt
; m
; m
= (recurse
? next_mnt(m
, mnt
) : NULL
))
2092 change_mnt_propagation(m
, type
);
2093 unlock_mount_hash();
2100 static bool has_locked_children(struct mount
*mnt
, struct dentry
*dentry
)
2102 struct mount
*child
;
2103 list_for_each_entry(child
, &mnt
->mnt_mounts
, mnt_child
) {
2104 if (!is_subdir(child
->mnt_mountpoint
, dentry
))
2107 if (child
->mnt
.mnt_flags
& MNT_LOCKED
)
2114 * do loopback mount.
2116 static int do_loopback(struct path
*path
, const char *old_name
,
2119 struct path old_path
;
2120 struct mount
*mnt
= NULL
, *old
, *parent
;
2121 struct mountpoint
*mp
;
2123 if (!old_name
|| !*old_name
)
2125 err
= kern_path(old_name
, LOOKUP_FOLLOW
|LOOKUP_AUTOMOUNT
, &old_path
);
2130 if (mnt_ns_loop(old_path
.dentry
))
2133 mp
= lock_mount(path
);
2138 old
= real_mount(old_path
.mnt
);
2139 parent
= real_mount(path
->mnt
);
2142 if (IS_MNT_UNBINDABLE(old
))
2145 if (!check_mnt(parent
))
2148 if (!check_mnt(old
) && old_path
.dentry
->d_op
!= &ns_dentry_operations
)
2151 if (!recurse
&& has_locked_children(old
, old_path
.dentry
))
2155 mnt
= copy_tree(old
, old_path
.dentry
, CL_COPY_MNT_NS_FILE
);
2157 mnt
= clone_mnt(old
, old_path
.dentry
, 0);
2164 mnt
->mnt
.mnt_flags
&= ~MNT_LOCKED
;
2166 err
= graft_tree(mnt
, parent
, mp
);
2169 umount_tree(mnt
, UMOUNT_SYNC
);
2170 unlock_mount_hash();
2175 path_put(&old_path
);
2179 static int change_mount_flags(struct vfsmount
*mnt
, int ms_flags
)
2182 int readonly_request
= 0;
2184 if (ms_flags
& MS_RDONLY
)
2185 readonly_request
= 1;
2186 if (readonly_request
== __mnt_is_readonly(mnt
))
2189 if (readonly_request
)
2190 error
= mnt_make_readonly(real_mount(mnt
));
2192 __mnt_unmake_readonly(real_mount(mnt
));
2197 * change filesystem flags. dir should be a physical root of filesystem.
2198 * If you've mounted a non-root directory somewhere and want to do remount
2199 * on it - tough luck.
2201 static int do_remount(struct path
*path
, int flags
, int mnt_flags
,
2205 struct super_block
*sb
= path
->mnt
->mnt_sb
;
2206 struct mount
*mnt
= real_mount(path
->mnt
);
2208 if (!check_mnt(mnt
))
2211 if (path
->dentry
!= path
->mnt
->mnt_root
)
2214 /* Don't allow changing of locked mnt flags.
2216 * No locks need to be held here while testing the various
2217 * MNT_LOCK flags because those flags can never be cleared
2218 * once they are set.
2220 if ((mnt
->mnt
.mnt_flags
& MNT_LOCK_READONLY
) &&
2221 !(mnt_flags
& MNT_READONLY
)) {
2224 if ((mnt
->mnt
.mnt_flags
& MNT_LOCK_NODEV
) &&
2225 !(mnt_flags
& MNT_NODEV
)) {
2228 if ((mnt
->mnt
.mnt_flags
& MNT_LOCK_NOSUID
) &&
2229 !(mnt_flags
& MNT_NOSUID
)) {
2232 if ((mnt
->mnt
.mnt_flags
& MNT_LOCK_NOEXEC
) &&
2233 !(mnt_flags
& MNT_NOEXEC
)) {
2236 if ((mnt
->mnt
.mnt_flags
& MNT_LOCK_ATIME
) &&
2237 ((mnt
->mnt
.mnt_flags
& MNT_ATIME_MASK
) != (mnt_flags
& MNT_ATIME_MASK
))) {
2241 err
= security_sb_remount(sb
, data
);
2245 down_write(&sb
->s_umount
);
2246 if (flags
& MS_BIND
)
2247 err
= change_mount_flags(path
->mnt
, flags
);
2248 else if (!capable(CAP_SYS_ADMIN
))
2251 err
= do_remount_sb(sb
, flags
, data
, 0);
2254 mnt_flags
|= mnt
->mnt
.mnt_flags
& ~MNT_USER_SETTABLE_MASK
;
2255 mnt
->mnt
.mnt_flags
= mnt_flags
;
2256 touch_mnt_namespace(mnt
->mnt_ns
);
2257 unlock_mount_hash();
2259 up_write(&sb
->s_umount
);
2263 static inline int tree_contains_unbindable(struct mount
*mnt
)
2266 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
)) {
2267 if (IS_MNT_UNBINDABLE(p
))
2273 static int do_move_mount(struct path
*path
, const char *old_name
)
2275 struct path old_path
, parent_path
;
2278 struct mountpoint
*mp
;
2280 if (!old_name
|| !*old_name
)
2282 err
= kern_path(old_name
, LOOKUP_FOLLOW
, &old_path
);
2286 mp
= lock_mount(path
);
2291 old
= real_mount(old_path
.mnt
);
2292 p
= real_mount(path
->mnt
);
2295 if (!check_mnt(p
) || !check_mnt(old
))
2298 if (old
->mnt
.mnt_flags
& MNT_LOCKED
)
2302 if (old_path
.dentry
!= old_path
.mnt
->mnt_root
)
2305 if (!mnt_has_parent(old
))
2308 if (d_is_dir(path
->dentry
) !=
2309 d_is_dir(old_path
.dentry
))
2312 * Don't move a mount residing in a shared parent.
2314 if (IS_MNT_SHARED(old
->mnt_parent
))
2317 * Don't move a mount tree containing unbindable mounts to a destination
2318 * mount which is shared.
2320 if (IS_MNT_SHARED(p
) && tree_contains_unbindable(old
))
2323 for (; mnt_has_parent(p
); p
= p
->mnt_parent
)
2327 err
= attach_recursive_mnt(old
, real_mount(path
->mnt
), mp
, &parent_path
);
2331 /* if the mount is moved, it should no longer be expire
2333 list_del_init(&old
->mnt_expire
);
2338 path_put(&parent_path
);
2339 path_put(&old_path
);
2343 static struct vfsmount
*fs_set_subtype(struct vfsmount
*mnt
, const char *fstype
)
2346 const char *subtype
= strchr(fstype
, '.');
2355 mnt
->mnt_sb
->s_subtype
= kstrdup(subtype
, GFP_KERNEL
);
2357 if (!mnt
->mnt_sb
->s_subtype
)
2363 return ERR_PTR(err
);
2367 * add a mount into a namespace's mount tree
2369 static int do_add_mount(struct mount
*newmnt
, struct path
*path
, int mnt_flags
)
2371 struct mountpoint
*mp
;
2372 struct mount
*parent
;
2375 mnt_flags
&= ~MNT_INTERNAL_FLAGS
;
2377 mp
= lock_mount(path
);
2381 parent
= real_mount(path
->mnt
);
2383 if (unlikely(!check_mnt(parent
))) {
2384 /* that's acceptable only for automounts done in private ns */
2385 if (!(mnt_flags
& MNT_SHRINKABLE
))
2387 /* ... and for those we'd better have mountpoint still alive */
2388 if (!parent
->mnt_ns
)
2392 /* Refuse the same filesystem on the same mount point */
2394 if (path
->mnt
->mnt_sb
== newmnt
->mnt
.mnt_sb
&&
2395 path
->mnt
->mnt_root
== path
->dentry
)
2399 if (d_is_symlink(newmnt
->mnt
.mnt_root
))
2402 newmnt
->mnt
.mnt_flags
= mnt_flags
;
2403 err
= graft_tree(newmnt
, parent
, mp
);
2410 static bool mount_too_revealing(struct vfsmount
*mnt
, int *new_mnt_flags
);
2413 * create a new mount for userspace and request it to be added into the
2416 static int do_new_mount(struct path
*path
, const char *fstype
, int flags
,
2417 int mnt_flags
, const char *name
, void *data
)
2419 struct file_system_type
*type
;
2420 struct vfsmount
*mnt
;
2426 type
= get_fs_type(fstype
);
2430 mnt
= vfs_kern_mount(type
, flags
, name
, data
);
2431 if (!IS_ERR(mnt
) && (type
->fs_flags
& FS_HAS_SUBTYPE
) &&
2432 !mnt
->mnt_sb
->s_subtype
)
2433 mnt
= fs_set_subtype(mnt
, fstype
);
2435 put_filesystem(type
);
2437 return PTR_ERR(mnt
);
2439 if (mount_too_revealing(mnt
, &mnt_flags
)) {
2444 err
= do_add_mount(real_mount(mnt
), path
, mnt_flags
);
2450 int finish_automount(struct vfsmount
*m
, struct path
*path
)
2452 struct mount
*mnt
= real_mount(m
);
2454 /* The new mount record should have at least 2 refs to prevent it being
2455 * expired before we get a chance to add it
2457 BUG_ON(mnt_get_count(mnt
) < 2);
2459 if (m
->mnt_sb
== path
->mnt
->mnt_sb
&&
2460 m
->mnt_root
== path
->dentry
) {
2465 err
= do_add_mount(mnt
, path
, path
->mnt
->mnt_flags
| MNT_SHRINKABLE
);
2469 /* remove m from any expiration list it may be on */
2470 if (!list_empty(&mnt
->mnt_expire
)) {
2472 list_del_init(&mnt
->mnt_expire
);
2481 * mnt_set_expiry - Put a mount on an expiration list
2482 * @mnt: The mount to list.
2483 * @expiry_list: The list to add the mount to.
2485 void mnt_set_expiry(struct vfsmount
*mnt
, struct list_head
*expiry_list
)
2489 list_add_tail(&real_mount(mnt
)->mnt_expire
, expiry_list
);
2493 EXPORT_SYMBOL(mnt_set_expiry
);
2496 * process a list of expirable mountpoints with the intent of discarding any
2497 * mountpoints that aren't in use and haven't been touched since last we came
2500 void mark_mounts_for_expiry(struct list_head
*mounts
)
2502 struct mount
*mnt
, *next
;
2503 LIST_HEAD(graveyard
);
2505 if (list_empty(mounts
))
2511 /* extract from the expiration list every vfsmount that matches the
2512 * following criteria:
2513 * - only referenced by its parent vfsmount
2514 * - still marked for expiry (marked on the last call here; marks are
2515 * cleared by mntput())
2517 list_for_each_entry_safe(mnt
, next
, mounts
, mnt_expire
) {
2518 if (!xchg(&mnt
->mnt_expiry_mark
, 1) ||
2519 propagate_mount_busy(mnt
, 1))
2521 list_move(&mnt
->mnt_expire
, &graveyard
);
2523 while (!list_empty(&graveyard
)) {
2524 mnt
= list_first_entry(&graveyard
, struct mount
, mnt_expire
);
2525 touch_mnt_namespace(mnt
->mnt_ns
);
2526 umount_tree(mnt
, UMOUNT_PROPAGATE
|UMOUNT_SYNC
);
2528 unlock_mount_hash();
2532 EXPORT_SYMBOL_GPL(mark_mounts_for_expiry
);
2535 * Ripoff of 'select_parent()'
2537 * search the list of submounts for a given mountpoint, and move any
2538 * shrinkable submounts to the 'graveyard' list.
2540 static int select_submounts(struct mount
*parent
, struct list_head
*graveyard
)
2542 struct mount
*this_parent
= parent
;
2543 struct list_head
*next
;
2547 next
= this_parent
->mnt_mounts
.next
;
2549 while (next
!= &this_parent
->mnt_mounts
) {
2550 struct list_head
*tmp
= next
;
2551 struct mount
*mnt
= list_entry(tmp
, struct mount
, mnt_child
);
2554 if (!(mnt
->mnt
.mnt_flags
& MNT_SHRINKABLE
))
2557 * Descend a level if the d_mounts list is non-empty.
2559 if (!list_empty(&mnt
->mnt_mounts
)) {
2564 if (!propagate_mount_busy(mnt
, 1)) {
2565 list_move_tail(&mnt
->mnt_expire
, graveyard
);
2570 * All done at this level ... ascend and resume the search
2572 if (this_parent
!= parent
) {
2573 next
= this_parent
->mnt_child
.next
;
2574 this_parent
= this_parent
->mnt_parent
;
2581 * process a list of expirable mountpoints with the intent of discarding any
2582 * submounts of a specific parent mountpoint
2584 * mount_lock must be held for write
2586 static void shrink_submounts(struct mount
*mnt
)
2588 LIST_HEAD(graveyard
);
2591 /* extract submounts of 'mountpoint' from the expiration list */
2592 while (select_submounts(mnt
, &graveyard
)) {
2593 while (!list_empty(&graveyard
)) {
2594 m
= list_first_entry(&graveyard
, struct mount
,
2596 touch_mnt_namespace(m
->mnt_ns
);
2597 umount_tree(m
, UMOUNT_PROPAGATE
|UMOUNT_SYNC
);
2603 * Some copy_from_user() implementations do not return the exact number of
2604 * bytes remaining to copy on a fault. But copy_mount_options() requires that.
2605 * Note that this function differs from copy_from_user() in that it will oops
2606 * on bad values of `to', rather than returning a short copy.
2608 static long exact_copy_from_user(void *to
, const void __user
* from
,
2612 const char __user
*f
= from
;
2615 if (!access_ok(VERIFY_READ
, from
, n
))
2619 if (__get_user(c
, f
)) {
2630 void *copy_mount_options(const void __user
* data
)
2639 copy
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
2641 return ERR_PTR(-ENOMEM
);
2643 /* We only care that *some* data at the address the user
2644 * gave us is valid. Just in case, we'll zero
2645 * the remainder of the page.
2647 /* copy_from_user cannot cross TASK_SIZE ! */
2648 size
= TASK_SIZE
- (unsigned long)data
;
2649 if (size
> PAGE_SIZE
)
2652 i
= size
- exact_copy_from_user(copy
, data
, size
);
2655 return ERR_PTR(-EFAULT
);
2658 memset(copy
+ i
, 0, PAGE_SIZE
- i
);
2662 char *copy_mount_string(const void __user
*data
)
2664 return data
? strndup_user(data
, PAGE_SIZE
) : NULL
;
2668 * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
2669 * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
2671 * data is a (void *) that can point to any structure up to
2672 * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
2673 * information (or be NULL).
2675 * Pre-0.97 versions of mount() didn't have a flags word.
2676 * When the flags word was introduced its top half was required
2677 * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
2678 * Therefore, if this magic number is present, it carries no information
2679 * and must be discarded.
2681 long do_mount(const char *dev_name
, const char __user
*dir_name
,
2682 const char *type_page
, unsigned long flags
, void *data_page
)
2689 if ((flags
& MS_MGC_MSK
) == MS_MGC_VAL
)
2690 flags
&= ~MS_MGC_MSK
;
2692 /* Basic sanity checks */
2694 ((char *)data_page
)[PAGE_SIZE
- 1] = 0;
2696 /* ... and get the mountpoint */
2697 retval
= user_path(dir_name
, &path
);
2701 retval
= security_sb_mount(dev_name
, &path
,
2702 type_page
, flags
, data_page
);
2703 if (!retval
&& !may_mount())
2705 if (!retval
&& (flags
& MS_MANDLOCK
) && !may_mandlock())
2710 /* Default to relatime unless overriden */
2711 if (!(flags
& MS_NOATIME
))
2712 mnt_flags
|= MNT_RELATIME
;
2714 /* Separate the per-mountpoint flags */
2715 if (flags
& MS_NOSUID
)
2716 mnt_flags
|= MNT_NOSUID
;
2717 if (flags
& MS_NODEV
)
2718 mnt_flags
|= MNT_NODEV
;
2719 if (flags
& MS_NOEXEC
)
2720 mnt_flags
|= MNT_NOEXEC
;
2721 if (flags
& MS_NOATIME
)
2722 mnt_flags
|= MNT_NOATIME
;
2723 if (flags
& MS_NODIRATIME
)
2724 mnt_flags
|= MNT_NODIRATIME
;
2725 if (flags
& MS_STRICTATIME
)
2726 mnt_flags
&= ~(MNT_RELATIME
| MNT_NOATIME
);
2727 if (flags
& MS_RDONLY
)
2728 mnt_flags
|= MNT_READONLY
;
2730 /* The default atime for remount is preservation */
2731 if ((flags
& MS_REMOUNT
) &&
2732 ((flags
& (MS_NOATIME
| MS_NODIRATIME
| MS_RELATIME
|
2733 MS_STRICTATIME
)) == 0)) {
2734 mnt_flags
&= ~MNT_ATIME_MASK
;
2735 mnt_flags
|= path
.mnt
->mnt_flags
& MNT_ATIME_MASK
;
2738 flags
&= ~(MS_NOSUID
| MS_NOEXEC
| MS_NODEV
| MS_ACTIVE
| MS_BORN
|
2739 MS_NOATIME
| MS_NODIRATIME
| MS_RELATIME
| MS_KERNMOUNT
|
2740 MS_STRICTATIME
| MS_NOREMOTELOCK
);
2742 if (flags
& MS_REMOUNT
)
2743 retval
= do_remount(&path
, flags
& ~MS_REMOUNT
, mnt_flags
,
2745 else if (flags
& MS_BIND
)
2746 retval
= do_loopback(&path
, dev_name
, flags
& MS_REC
);
2747 else if (flags
& (MS_SHARED
| MS_PRIVATE
| MS_SLAVE
| MS_UNBINDABLE
))
2748 retval
= do_change_type(&path
, flags
);
2749 else if (flags
& MS_MOVE
)
2750 retval
= do_move_mount(&path
, dev_name
);
2752 retval
= do_new_mount(&path
, type_page
, flags
, mnt_flags
,
2753 dev_name
, data_page
);
2759 static struct ucounts
*inc_mnt_namespaces(struct user_namespace
*ns
)
2761 return inc_ucount(ns
, current_euid(), UCOUNT_MNT_NAMESPACES
);
2764 static void dec_mnt_namespaces(struct ucounts
*ucounts
)
2766 dec_ucount(ucounts
, UCOUNT_MNT_NAMESPACES
);
2769 static void free_mnt_ns(struct mnt_namespace
*ns
)
2771 ns_free_inum(&ns
->ns
);
2772 dec_mnt_namespaces(ns
->ucounts
);
2773 put_user_ns(ns
->user_ns
);
2778 * Assign a sequence number so we can detect when we attempt to bind
2779 * mount a reference to an older mount namespace into the current
2780 * mount namespace, preventing reference counting loops. A 64bit
2781 * number incrementing at 10Ghz will take 12,427 years to wrap which
2782 * is effectively never, so we can ignore the possibility.
2784 static atomic64_t mnt_ns_seq
= ATOMIC64_INIT(1);
2786 static struct mnt_namespace
*alloc_mnt_ns(struct user_namespace
*user_ns
)
2788 struct mnt_namespace
*new_ns
;
2789 struct ucounts
*ucounts
;
2792 ucounts
= inc_mnt_namespaces(user_ns
);
2794 return ERR_PTR(-ENOSPC
);
2796 new_ns
= kmalloc(sizeof(struct mnt_namespace
), GFP_KERNEL
);
2798 dec_mnt_namespaces(ucounts
);
2799 return ERR_PTR(-ENOMEM
);
2801 ret
= ns_alloc_inum(&new_ns
->ns
);
2804 dec_mnt_namespaces(ucounts
);
2805 return ERR_PTR(ret
);
2807 new_ns
->ns
.ops
= &mntns_operations
;
2808 new_ns
->seq
= atomic64_add_return(1, &mnt_ns_seq
);
2809 atomic_set(&new_ns
->count
, 1);
2810 new_ns
->root
= NULL
;
2811 INIT_LIST_HEAD(&new_ns
->list
);
2812 init_waitqueue_head(&new_ns
->poll
);
2814 new_ns
->user_ns
= get_user_ns(user_ns
);
2815 new_ns
->ucounts
= ucounts
;
2817 new_ns
->pending_mounts
= 0;
2822 struct mnt_namespace
*copy_mnt_ns(unsigned long flags
, struct mnt_namespace
*ns
,
2823 struct user_namespace
*user_ns
, struct fs_struct
*new_fs
)
2825 struct mnt_namespace
*new_ns
;
2826 struct vfsmount
*rootmnt
= NULL
, *pwdmnt
= NULL
;
2827 struct mount
*p
, *q
;
2834 if (likely(!(flags
& CLONE_NEWNS
))) {
2841 new_ns
= alloc_mnt_ns(user_ns
);
2846 /* First pass: copy the tree topology */
2847 copy_flags
= CL_COPY_UNBINDABLE
| CL_EXPIRE
;
2848 if (user_ns
!= ns
->user_ns
)
2849 copy_flags
|= CL_SHARED_TO_SLAVE
| CL_UNPRIVILEGED
;
2850 new = copy_tree(old
, old
->mnt
.mnt_root
, copy_flags
);
2853 free_mnt_ns(new_ns
);
2854 return ERR_CAST(new);
2857 list_add_tail(&new_ns
->list
, &new->mnt_list
);
2860 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
2861 * as belonging to new namespace. We have already acquired a private
2862 * fs_struct, so tsk->fs->lock is not needed.
2870 if (&p
->mnt
== new_fs
->root
.mnt
) {
2871 new_fs
->root
.mnt
= mntget(&q
->mnt
);
2874 if (&p
->mnt
== new_fs
->pwd
.mnt
) {
2875 new_fs
->pwd
.mnt
= mntget(&q
->mnt
);
2879 p
= next_mnt(p
, old
);
2880 q
= next_mnt(q
, new);
2883 while (p
->mnt
.mnt_root
!= q
->mnt
.mnt_root
)
2884 p
= next_mnt(p
, old
);
2897 * create_mnt_ns - creates a private namespace and adds a root filesystem
2898 * @mnt: pointer to the new root filesystem mountpoint
2900 static struct mnt_namespace
*create_mnt_ns(struct vfsmount
*m
)
2902 struct mnt_namespace
*new_ns
= alloc_mnt_ns(&init_user_ns
);
2903 if (!IS_ERR(new_ns
)) {
2904 struct mount
*mnt
= real_mount(m
);
2905 mnt
->mnt_ns
= new_ns
;
2908 list_add(&mnt
->mnt_list
, &new_ns
->list
);
2915 struct dentry
*mount_subtree(struct vfsmount
*mnt
, const char *name
)
2917 struct mnt_namespace
*ns
;
2918 struct super_block
*s
;
2922 ns
= create_mnt_ns(mnt
);
2924 return ERR_CAST(ns
);
2926 err
= vfs_path_lookup(mnt
->mnt_root
, mnt
,
2927 name
, LOOKUP_FOLLOW
|LOOKUP_AUTOMOUNT
, &path
);
2932 return ERR_PTR(err
);
2934 /* trade a vfsmount reference for active sb one */
2935 s
= path
.mnt
->mnt_sb
;
2936 atomic_inc(&s
->s_active
);
2938 /* lock the sucker */
2939 down_write(&s
->s_umount
);
2940 /* ... and return the root of (sub)tree on it */
2943 EXPORT_SYMBOL(mount_subtree
);
2945 SYSCALL_DEFINE5(mount
, char __user
*, dev_name
, char __user
*, dir_name
,
2946 char __user
*, type
, unsigned long, flags
, void __user
*, data
)
2953 kernel_type
= copy_mount_string(type
);
2954 ret
= PTR_ERR(kernel_type
);
2955 if (IS_ERR(kernel_type
))
2958 kernel_dev
= copy_mount_string(dev_name
);
2959 ret
= PTR_ERR(kernel_dev
);
2960 if (IS_ERR(kernel_dev
))
2963 options
= copy_mount_options(data
);
2964 ret
= PTR_ERR(options
);
2965 if (IS_ERR(options
))
2968 ret
= do_mount(kernel_dev
, dir_name
, kernel_type
, flags
, options
);
2980 * Return true if path is reachable from root
2982 * namespace_sem or mount_lock is held
2984 bool is_path_reachable(struct mount
*mnt
, struct dentry
*dentry
,
2985 const struct path
*root
)
2987 while (&mnt
->mnt
!= root
->mnt
&& mnt_has_parent(mnt
)) {
2988 dentry
= mnt
->mnt_mountpoint
;
2989 mnt
= mnt
->mnt_parent
;
2991 return &mnt
->mnt
== root
->mnt
&& is_subdir(dentry
, root
->dentry
);
2994 bool path_is_under(struct path
*path1
, struct path
*path2
)
2997 read_seqlock_excl(&mount_lock
);
2998 res
= is_path_reachable(real_mount(path1
->mnt
), path1
->dentry
, path2
);
2999 read_sequnlock_excl(&mount_lock
);
3002 EXPORT_SYMBOL(path_is_under
);
3005 * pivot_root Semantics:
3006 * Moves the root file system of the current process to the directory put_old,
3007 * makes new_root as the new root file system of the current process, and sets
3008 * root/cwd of all processes which had them on the current root to new_root.
3011 * The new_root and put_old must be directories, and must not be on the
3012 * same file system as the current process root. The put_old must be
3013 * underneath new_root, i.e. adding a non-zero number of /.. to the string
3014 * pointed to by put_old must yield the same directory as new_root. No other
3015 * file system may be mounted on put_old. After all, new_root is a mountpoint.
3017 * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
3018 * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives
3019 * in this situation.
3022 * - we don't move root/cwd if they are not at the root (reason: if something
3023 * cared enough to change them, it's probably wrong to force them elsewhere)
3024 * - it's okay to pick a root that isn't the root of a file system, e.g.
3025 * /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
3026 * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
3029 SYSCALL_DEFINE2(pivot_root
, const char __user
*, new_root
,
3030 const char __user
*, put_old
)
3032 struct path
new, old
, parent_path
, root_parent
, root
;
3033 struct mount
*new_mnt
, *root_mnt
, *old_mnt
;
3034 struct mountpoint
*old_mp
, *root_mp
;
3040 error
= user_path_dir(new_root
, &new);
3044 error
= user_path_dir(put_old
, &old
);
3048 error
= security_sb_pivotroot(&old
, &new);
3052 get_fs_root(current
->fs
, &root
);
3053 old_mp
= lock_mount(&old
);
3054 error
= PTR_ERR(old_mp
);
3059 new_mnt
= real_mount(new.mnt
);
3060 root_mnt
= real_mount(root
.mnt
);
3061 old_mnt
= real_mount(old
.mnt
);
3062 if (IS_MNT_SHARED(old_mnt
) ||
3063 IS_MNT_SHARED(new_mnt
->mnt_parent
) ||
3064 IS_MNT_SHARED(root_mnt
->mnt_parent
))
3066 if (!check_mnt(root_mnt
) || !check_mnt(new_mnt
))
3068 if (new_mnt
->mnt
.mnt_flags
& MNT_LOCKED
)
3071 if (d_unlinked(new.dentry
))
3074 if (new_mnt
== root_mnt
|| old_mnt
== root_mnt
)
3075 goto out4
; /* loop, on the same file system */
3077 if (root
.mnt
->mnt_root
!= root
.dentry
)
3078 goto out4
; /* not a mountpoint */
3079 if (!mnt_has_parent(root_mnt
))
3080 goto out4
; /* not attached */
3081 root_mp
= root_mnt
->mnt_mp
;
3082 if (new.mnt
->mnt_root
!= new.dentry
)
3083 goto out4
; /* not a mountpoint */
3084 if (!mnt_has_parent(new_mnt
))
3085 goto out4
; /* not attached */
3086 /* make sure we can reach put_old from new_root */
3087 if (!is_path_reachable(old_mnt
, old
.dentry
, &new))
3089 /* make certain new is below the root */
3090 if (!is_path_reachable(new_mnt
, new.dentry
, &root
))
3092 root_mp
->m_count
++; /* pin it so it won't go away */
3094 detach_mnt(new_mnt
, &parent_path
);
3095 detach_mnt(root_mnt
, &root_parent
);
3096 if (root_mnt
->mnt
.mnt_flags
& MNT_LOCKED
) {
3097 new_mnt
->mnt
.mnt_flags
|= MNT_LOCKED
;
3098 root_mnt
->mnt
.mnt_flags
&= ~MNT_LOCKED
;
3100 /* mount old root on put_old */
3101 attach_mnt(root_mnt
, old_mnt
, old_mp
);
3102 /* mount new_root on / */
3103 attach_mnt(new_mnt
, real_mount(root_parent
.mnt
), root_mp
);
3104 touch_mnt_namespace(current
->nsproxy
->mnt_ns
);
3105 /* A moved mount should not expire automatically */
3106 list_del_init(&new_mnt
->mnt_expire
);
3107 unlock_mount_hash();
3108 chroot_fs_refs(&root
, &new);
3109 put_mountpoint(root_mp
);
3112 unlock_mount(old_mp
);
3114 path_put(&root_parent
);
3115 path_put(&parent_path
);
3127 static void __init
init_mount_tree(void)
3129 struct vfsmount
*mnt
;
3130 struct mnt_namespace
*ns
;
3132 struct file_system_type
*type
;
3134 type
= get_fs_type("rootfs");
3136 panic("Can't find rootfs type");
3137 mnt
= vfs_kern_mount(type
, 0, "rootfs", NULL
);
3138 put_filesystem(type
);
3140 panic("Can't create rootfs");
3142 ns
= create_mnt_ns(mnt
);
3144 panic("Can't allocate initial namespace");
3146 init_task
.nsproxy
->mnt_ns
= ns
;
3150 root
.dentry
= mnt
->mnt_root
;
3151 mnt
->mnt_flags
|= MNT_LOCKED
;
3153 set_fs_pwd(current
->fs
, &root
);
3154 set_fs_root(current
->fs
, &root
);
3157 void __init
mnt_init(void)
3162 mnt_cache
= kmem_cache_create("mnt_cache", sizeof(struct mount
),
3163 0, SLAB_HWCACHE_ALIGN
| SLAB_PANIC
, NULL
);
3165 mount_hashtable
= alloc_large_system_hash("Mount-cache",
3166 sizeof(struct hlist_head
),
3169 &m_hash_shift
, &m_hash_mask
, 0, 0);
3170 mountpoint_hashtable
= alloc_large_system_hash("Mountpoint-cache",
3171 sizeof(struct hlist_head
),
3174 &mp_hash_shift
, &mp_hash_mask
, 0, 0);
3176 if (!mount_hashtable
|| !mountpoint_hashtable
)
3177 panic("Failed to allocate mount hash table\n");
3179 for (u
= 0; u
<= m_hash_mask
; u
++)
3180 INIT_HLIST_HEAD(&mount_hashtable
[u
]);
3181 for (u
= 0; u
<= mp_hash_mask
; u
++)
3182 INIT_HLIST_HEAD(&mountpoint_hashtable
[u
]);
3188 printk(KERN_WARNING
"%s: sysfs_init error: %d\n",
3190 fs_kobj
= kobject_create_and_add("fs", NULL
);
3192 printk(KERN_WARNING
"%s: kobj create error\n", __func__
);
3197 void put_mnt_ns(struct mnt_namespace
*ns
)
3199 if (!atomic_dec_and_test(&ns
->count
))
3201 drop_collected_mounts(&ns
->root
->mnt
);
3205 struct vfsmount
*kern_mount_data(struct file_system_type
*type
, void *data
)
3207 struct vfsmount
*mnt
;
3208 mnt
= vfs_kern_mount(type
, MS_KERNMOUNT
, type
->name
, data
);
3211 * it is a longterm mount, don't release mnt until
3212 * we unmount before file sys is unregistered
3214 real_mount(mnt
)->mnt_ns
= MNT_NS_INTERNAL
;
3218 EXPORT_SYMBOL_GPL(kern_mount_data
);
3220 void kern_unmount(struct vfsmount
*mnt
)
3222 /* release long term mount so mount point can be released */
3223 if (!IS_ERR_OR_NULL(mnt
)) {
3224 real_mount(mnt
)->mnt_ns
= NULL
;
3225 synchronize_rcu(); /* yecchhh... */
3229 EXPORT_SYMBOL(kern_unmount
);
3231 bool our_mnt(struct vfsmount
*mnt
)
3233 return check_mnt(real_mount(mnt
));
3236 bool current_chrooted(void)
3238 /* Does the current process have a non-standard root */
3239 struct path ns_root
;
3240 struct path fs_root
;
3243 /* Find the namespace root */
3244 ns_root
.mnt
= ¤t
->nsproxy
->mnt_ns
->root
->mnt
;
3245 ns_root
.dentry
= ns_root
.mnt
->mnt_root
;
3247 while (d_mountpoint(ns_root
.dentry
) && follow_down_one(&ns_root
))
3250 get_fs_root(current
->fs
, &fs_root
);
3252 chrooted
= !path_equal(&fs_root
, &ns_root
);
3260 static bool mnt_already_visible(struct mnt_namespace
*ns
, struct vfsmount
*new,
3263 int new_flags
= *new_mnt_flags
;
3265 bool visible
= false;
3267 down_read(&namespace_sem
);
3268 list_for_each_entry(mnt
, &ns
->list
, mnt_list
) {
3269 struct mount
*child
;
3272 if (mnt
->mnt
.mnt_sb
->s_type
!= new->mnt_sb
->s_type
)
3275 /* This mount is not fully visible if it's root directory
3276 * is not the root directory of the filesystem.
3278 if (mnt
->mnt
.mnt_root
!= mnt
->mnt
.mnt_sb
->s_root
)
3281 /* A local view of the mount flags */
3282 mnt_flags
= mnt
->mnt
.mnt_flags
;
3284 /* Don't miss readonly hidden in the superblock flags */
3285 if (mnt
->mnt
.mnt_sb
->s_flags
& MS_RDONLY
)
3286 mnt_flags
|= MNT_LOCK_READONLY
;
3288 /* Verify the mount flags are equal to or more permissive
3289 * than the proposed new mount.
3291 if ((mnt_flags
& MNT_LOCK_READONLY
) &&
3292 !(new_flags
& MNT_READONLY
))
3294 if ((mnt_flags
& MNT_LOCK_ATIME
) &&
3295 ((mnt_flags
& MNT_ATIME_MASK
) != (new_flags
& MNT_ATIME_MASK
)))
3298 /* This mount is not fully visible if there are any
3299 * locked child mounts that cover anything except for
3300 * empty directories.
3302 list_for_each_entry(child
, &mnt
->mnt_mounts
, mnt_child
) {
3303 struct inode
*inode
= child
->mnt_mountpoint
->d_inode
;
3304 /* Only worry about locked mounts */
3305 if (!(child
->mnt
.mnt_flags
& MNT_LOCKED
))
3307 /* Is the directory permanetly empty? */
3308 if (!is_empty_dir_inode(inode
))
3311 /* Preserve the locked attributes */
3312 *new_mnt_flags
|= mnt_flags
& (MNT_LOCK_READONLY
| \
3319 up_read(&namespace_sem
);
3323 static bool mount_too_revealing(struct vfsmount
*mnt
, int *new_mnt_flags
)
3325 const unsigned long required_iflags
= SB_I_NOEXEC
| SB_I_NODEV
;
3326 struct mnt_namespace
*ns
= current
->nsproxy
->mnt_ns
;
3327 unsigned long s_iflags
;
3329 if (ns
->user_ns
== &init_user_ns
)
3332 /* Can this filesystem be too revealing? */
3333 s_iflags
= mnt
->mnt_sb
->s_iflags
;
3334 if (!(s_iflags
& SB_I_USERNS_VISIBLE
))
3337 if ((s_iflags
& required_iflags
) != required_iflags
) {
3338 WARN_ONCE(1, "Expected s_iflags to contain 0x%lx\n",
3343 return !mnt_already_visible(ns
, mnt
, new_mnt_flags
);
3346 bool mnt_may_suid(struct vfsmount
*mnt
)
3349 * Foreign mounts (accessed via fchdir or through /proc
3350 * symlinks) are always treated as if they are nosuid. This
3351 * prevents namespaces from trusting potentially unsafe
3352 * suid/sgid bits, file caps, or security labels that originate
3353 * in other namespaces.
3355 return !(mnt
->mnt_flags
& MNT_NOSUID
) && check_mnt(real_mount(mnt
)) &&
3356 current_in_userns(mnt
->mnt_sb
->s_user_ns
);
3359 static struct ns_common
*mntns_get(struct task_struct
*task
)
3361 struct ns_common
*ns
= NULL
;
3362 struct nsproxy
*nsproxy
;
3365 nsproxy
= task
->nsproxy
;
3367 ns
= &nsproxy
->mnt_ns
->ns
;
3368 get_mnt_ns(to_mnt_ns(ns
));
3375 static void mntns_put(struct ns_common
*ns
)
3377 put_mnt_ns(to_mnt_ns(ns
));
3380 static int mntns_install(struct nsproxy
*nsproxy
, struct ns_common
*ns
)
3382 struct fs_struct
*fs
= current
->fs
;
3383 struct mnt_namespace
*mnt_ns
= to_mnt_ns(ns
);
3386 if (!ns_capable(mnt_ns
->user_ns
, CAP_SYS_ADMIN
) ||
3387 !ns_capable(current_user_ns(), CAP_SYS_CHROOT
) ||
3388 !ns_capable(current_user_ns(), CAP_SYS_ADMIN
))
3395 put_mnt_ns(nsproxy
->mnt_ns
);
3396 nsproxy
->mnt_ns
= mnt_ns
;
3399 root
.mnt
= &mnt_ns
->root
->mnt
;
3400 root
.dentry
= mnt_ns
->root
->mnt
.mnt_root
;
3402 while(d_mountpoint(root
.dentry
) && follow_down_one(&root
))
3405 /* Update the pwd and root */
3406 set_fs_pwd(fs
, &root
);
3407 set_fs_root(fs
, &root
);
3413 static struct user_namespace
*mntns_owner(struct ns_common
*ns
)
3415 return to_mnt_ns(ns
)->user_ns
;
3418 const struct proc_ns_operations mntns_operations
= {
3420 .type
= CLONE_NEWNS
,
3423 .install
= mntns_install
,
3424 .owner
= mntns_owner
,