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8#include <linux/mnt_namespace.h>
9#include <linux/mount.h>
10#include <linux/fs.h>
11#include <linux/nsproxy.h>
12#include <uapi/linux/mount.h>
13#include "internal.h"
14#include "pnode.h"
15
16
17static inline struct mount *next_peer(struct mount *p)
18{
19 return list_entry(p->mnt_share.next, struct mount, mnt_share);
20}
21
22static inline struct mount *first_slave(struct mount *p)
23{
24 return list_entry(p->mnt_slave_list.next, struct mount, mnt_slave);
25}
26
27static inline struct mount *last_slave(struct mount *p)
28{
29 return list_entry(p->mnt_slave_list.prev, struct mount, mnt_slave);
30}
31
32static inline struct mount *next_slave(struct mount *p)
33{
34 return list_entry(p->mnt_slave.next, struct mount, mnt_slave);
35}
36
37static struct mount *get_peer_under_root(struct mount *mnt,
38 struct mnt_namespace *ns,
39 const struct path *root)
40{
41 struct mount *m = mnt;
42
43 do {
44
45 if (m->mnt_ns == ns && is_path_reachable(m, m->mnt.mnt_root, root))
46 return m;
47
48 m = next_peer(m);
49 } while (m != mnt);
50
51 return NULL;
52}
53
54
55
56
57
58
59
60int get_dominating_id(struct mount *mnt, const struct path *root)
61{
62 struct mount *m;
63
64 for (m = mnt->mnt_master; m != NULL; m = m->mnt_master) {
65 struct mount *d = get_peer_under_root(m, mnt->mnt_ns, root);
66 if (d)
67 return d->mnt_group_id;
68 }
69
70 return 0;
71}
72
73static int do_make_slave(struct mount *mnt)
74{
75 struct mount *master, *slave_mnt;
76
77 if (list_empty(&mnt->mnt_share)) {
78 if (IS_MNT_SHARED(mnt)) {
79 mnt_release_group_id(mnt);
80 CLEAR_MNT_SHARED(mnt);
81 }
82 master = mnt->mnt_master;
83 if (!master) {
84 struct list_head *p = &mnt->mnt_slave_list;
85 while (!list_empty(p)) {
86 slave_mnt = list_first_entry(p,
87 struct mount, mnt_slave);
88 list_del_init(&slave_mnt->mnt_slave);
89 slave_mnt->mnt_master = NULL;
90 }
91 return 0;
92 }
93 } else {
94 struct mount *m;
95
96
97
98
99
100 for (m = master = next_peer(mnt); m != mnt; m = next_peer(m)) {
101 if (m->mnt.mnt_root == mnt->mnt.mnt_root) {
102 master = m;
103 break;
104 }
105 }
106 list_del_init(&mnt->mnt_share);
107 mnt->mnt_group_id = 0;
108 CLEAR_MNT_SHARED(mnt);
109 }
110 list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave)
111 slave_mnt->mnt_master = master;
112 list_move(&mnt->mnt_slave, &master->mnt_slave_list);
113 list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev);
114 INIT_LIST_HEAD(&mnt->mnt_slave_list);
115 mnt->mnt_master = master;
116 return 0;
117}
118
119
120
121
122void change_mnt_propagation(struct mount *mnt, int type)
123{
124 if (type == MS_SHARED) {
125 set_mnt_shared(mnt);
126 return;
127 }
128 do_make_slave(mnt);
129 if (type != MS_SLAVE) {
130 list_del_init(&mnt->mnt_slave);
131 mnt->mnt_master = NULL;
132 if (type == MS_UNBINDABLE)
133 mnt->mnt.mnt_flags |= MNT_UNBINDABLE;
134 else
135 mnt->mnt.mnt_flags &= ~MNT_UNBINDABLE;
136 }
137}
138
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147
148
149static struct mount *propagation_next(struct mount *m,
150 struct mount *origin)
151{
152
153 if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
154 return first_slave(m);
155
156 while (1) {
157 struct mount *master = m->mnt_master;
158
159 if (master == origin->mnt_master) {
160 struct mount *next = next_peer(m);
161 return (next == origin) ? NULL : next;
162 } else if (m->mnt_slave.next != &master->mnt_slave_list)
163 return next_slave(m);
164
165
166 m = master;
167 }
168}
169
170static struct mount *skip_propagation_subtree(struct mount *m,
171 struct mount *origin)
172{
173
174
175
176
177 if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
178 m = last_slave(m);
179
180 return m;
181}
182
183static struct mount *next_group(struct mount *m, struct mount *origin)
184{
185 while (1) {
186 while (1) {
187 struct mount *next;
188 if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
189 return first_slave(m);
190 next = next_peer(m);
191 if (m->mnt_group_id == origin->mnt_group_id) {
192 if (next == origin)
193 return NULL;
194 } else if (m->mnt_slave.next != &next->mnt_slave)
195 break;
196 m = next;
197 }
198
199 while (1) {
200 struct mount *master = m->mnt_master;
201 if (m->mnt_slave.next != &master->mnt_slave_list)
202 return next_slave(m);
203 m = next_peer(master);
204 if (master->mnt_group_id == origin->mnt_group_id)
205 break;
206 if (master->mnt_slave.next == &m->mnt_slave)
207 break;
208 m = master;
209 }
210 if (m == origin)
211 return NULL;
212 }
213}
214
215
216static struct mount *last_dest, *first_source, *last_source, *dest_master;
217static struct mountpoint *mp;
218static struct hlist_head *list;
219
220static inline bool peers(struct mount *m1, struct mount *m2)
221{
222 return m1->mnt_group_id == m2->mnt_group_id && m1->mnt_group_id;
223}
224
225static int propagate_one(struct mount *m)
226{
227 struct mount *child;
228 int type;
229
230 if (IS_MNT_NEW(m))
231 return 0;
232
233 if (!is_subdir(mp->m_dentry, m->mnt.mnt_root))
234 return 0;
235 if (peers(m, last_dest)) {
236 type = CL_MAKE_SHARED;
237 } else {
238 struct mount *n, *p;
239 bool done;
240 for (n = m; ; n = p) {
241 p = n->mnt_master;
242 if (p == dest_master || IS_MNT_MARKED(p))
243 break;
244 }
245 do {
246 struct mount *parent = last_source->mnt_parent;
247 if (last_source == first_source)
248 break;
249 done = parent->mnt_master == p;
250 if (done && peers(n, parent))
251 break;
252 last_source = last_source->mnt_master;
253 } while (!done);
254
255 type = CL_SLAVE;
256
257 if (IS_MNT_SHARED(m))
258 type |= CL_MAKE_SHARED;
259 }
260
261 child = copy_tree(last_source, last_source->mnt.mnt_root, type);
262 if (IS_ERR(child))
263 return PTR_ERR(child);
264 mnt_set_mountpoint(m, mp, child);
265 last_dest = m;
266 last_source = child;
267 if (m->mnt_master != dest_master) {
268 read_seqlock_excl(&mount_lock);
269 SET_MNT_MARK(m->mnt_master);
270 read_sequnlock_excl(&mount_lock);
271 }
272 hlist_add_head(&child->mnt_hash, list);
273 return count_mounts(m->mnt_ns, child);
274}
275
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288
289int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp,
290 struct mount *source_mnt, struct hlist_head *tree_list)
291{
292 struct mount *m, *n;
293 int ret = 0;
294
295
296
297
298
299
300 last_dest = dest_mnt;
301 first_source = source_mnt;
302 last_source = source_mnt;
303 mp = dest_mp;
304 list = tree_list;
305 dest_master = dest_mnt->mnt_master;
306
307
308 for (n = next_peer(dest_mnt); n != dest_mnt; n = next_peer(n)) {
309 ret = propagate_one(n);
310 if (ret)
311 goto out;
312 }
313
314
315 for (m = next_group(dest_mnt, dest_mnt); m;
316 m = next_group(m, dest_mnt)) {
317
318 n = m;
319 do {
320 ret = propagate_one(n);
321 if (ret)
322 goto out;
323 n = next_peer(n);
324 } while (n != m);
325 }
326out:
327 read_seqlock_excl(&mount_lock);
328 hlist_for_each_entry(n, tree_list, mnt_hash) {
329 m = n->mnt_parent;
330 if (m->mnt_master != dest_mnt->mnt_master)
331 CLEAR_MNT_MARK(m->mnt_master);
332 }
333 read_sequnlock_excl(&mount_lock);
334 return ret;
335}
336
337static struct mount *find_topper(struct mount *mnt)
338{
339
340 struct mount *child;
341
342 if (!list_is_singular(&mnt->mnt_mounts))
343 return NULL;
344
345 child = list_first_entry(&mnt->mnt_mounts, struct mount, mnt_child);
346 if (child->mnt_mountpoint != mnt->mnt.mnt_root)
347 return NULL;
348
349 return child;
350}
351
352
353
354
355static inline int do_refcount_check(struct mount *mnt, int count)
356{
357 return mnt_get_count(mnt) > count;
358}
359
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369
370int propagate_mount_busy(struct mount *mnt, int refcnt)
371{
372 struct mount *m, *child, *topper;
373 struct mount *parent = mnt->mnt_parent;
374
375 if (mnt == parent)
376 return do_refcount_check(mnt, refcnt);
377
378
379
380
381
382
383 if (!list_empty(&mnt->mnt_mounts) || do_refcount_check(mnt, refcnt))
384 return 1;
385
386 for (m = propagation_next(parent, parent); m;
387 m = propagation_next(m, parent)) {
388 int count = 1;
389 child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint);
390 if (!child)
391 continue;
392
393
394
395
396 topper = find_topper(child);
397 if (topper)
398 count += 1;
399 else if (!list_empty(&child->mnt_mounts))
400 continue;
401
402 if (do_refcount_check(child, count))
403 return 1;
404 }
405 return 0;
406}
407
408
409
410
411
412
413void propagate_mount_unlock(struct mount *mnt)
414{
415 struct mount *parent = mnt->mnt_parent;
416 struct mount *m, *child;
417
418 BUG_ON(parent == mnt);
419
420 for (m = propagation_next(parent, parent); m;
421 m = propagation_next(m, parent)) {
422 child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint);
423 if (child)
424 child->mnt.mnt_flags &= ~MNT_LOCKED;
425 }
426}
427
428static void umount_one(struct mount *mnt, struct list_head *to_umount)
429{
430 CLEAR_MNT_MARK(mnt);
431 mnt->mnt.mnt_flags |= MNT_UMOUNT;
432 list_del_init(&mnt->mnt_child);
433 list_del_init(&mnt->mnt_umounting);
434 list_move_tail(&mnt->mnt_list, to_umount);
435}
436
437
438
439
440
441static bool __propagate_umount(struct mount *mnt,
442 struct list_head *to_umount,
443 struct list_head *to_restore)
444{
445 bool progress = false;
446 struct mount *child;
447
448
449
450
451
452 if (mnt->mnt.mnt_flags & (MNT_UMOUNT | MNT_MARKED))
453 goto out;
454
455
456
457
458 list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) {
459 if (child->mnt_mountpoint == mnt->mnt.mnt_root)
460 continue;
461 if (!list_empty(&child->mnt_umounting) && IS_MNT_MARKED(child))
462 continue;
463
464 goto children;
465 }
466
467
468 SET_MNT_MARK(mnt);
469 progress = true;
470
471
472 if (!IS_MNT_LOCKED(mnt)) {
473 umount_one(mnt, to_umount);
474 } else {
475children:
476 list_move_tail(&mnt->mnt_umounting, to_restore);
477 }
478out:
479 return progress;
480}
481
482static void umount_list(struct list_head *to_umount,
483 struct list_head *to_restore)
484{
485 struct mount *mnt, *child, *tmp;
486 list_for_each_entry(mnt, to_umount, mnt_list) {
487 list_for_each_entry_safe(child, tmp, &mnt->mnt_mounts, mnt_child) {
488
489 if (child->mnt_mountpoint == mnt->mnt.mnt_root)
490 list_move_tail(&child->mnt_umounting, to_restore);
491 else
492 umount_one(child, to_umount);
493 }
494 }
495}
496
497static void restore_mounts(struct list_head *to_restore)
498{
499
500 while (!list_empty(to_restore)) {
501 struct mount *mnt, *parent;
502 struct mountpoint *mp;
503
504 mnt = list_first_entry(to_restore, struct mount, mnt_umounting);
505 CLEAR_MNT_MARK(mnt);
506 list_del_init(&mnt->mnt_umounting);
507
508
509 mp = mnt->mnt_mp;
510 parent = mnt->mnt_parent;
511 while (parent->mnt.mnt_flags & MNT_UMOUNT) {
512 mp = parent->mnt_mp;
513 parent = parent->mnt_parent;
514 }
515 if (parent != mnt->mnt_parent)
516 mnt_change_mountpoint(parent, mp, mnt);
517 }
518}
519
520static void cleanup_umount_visitations(struct list_head *visited)
521{
522 while (!list_empty(visited)) {
523 struct mount *mnt =
524 list_first_entry(visited, struct mount, mnt_umounting);
525 list_del_init(&mnt->mnt_umounting);
526 }
527}
528
529
530
531
532
533
534
535
536int propagate_umount(struct list_head *list)
537{
538 struct mount *mnt;
539 LIST_HEAD(to_restore);
540 LIST_HEAD(to_umount);
541 LIST_HEAD(visited);
542
543
544 list_for_each_entry_reverse(mnt, list, mnt_list) {
545 struct mount *parent = mnt->mnt_parent;
546 struct mount *m;
547
548
549
550
551
552
553
554 if (!list_empty(&mnt->mnt_umounting))
555 continue;
556
557 list_add_tail(&mnt->mnt_umounting, &visited);
558 for (m = propagation_next(parent, parent); m;
559 m = propagation_next(m, parent)) {
560 struct mount *child = __lookup_mnt(&m->mnt,
561 mnt->mnt_mountpoint);
562 if (!child)
563 continue;
564
565 if (!list_empty(&child->mnt_umounting)) {
566
567
568
569
570
571
572
573 m = skip_propagation_subtree(m, parent);
574 continue;
575 } else if (child->mnt.mnt_flags & MNT_UMOUNT) {
576
577
578
579
580
581
582 list_add_tail(&child->mnt_umounting, &visited);
583 continue;
584 }
585
586
587 while (__propagate_umount(child,
588 &to_umount, &to_restore)) {
589
590 child = child->mnt_parent;
591 if (list_empty(&child->mnt_umounting))
592 break;
593 }
594 }
595 }
596
597 umount_list(&to_umount, &to_restore);
598 restore_mounts(&to_restore);
599 cleanup_umount_visitations(&visited);
600 list_splice_tail(&to_umount, list);
601
602 return 0;
603}
604