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9#include <linux/mnt_namespace.h>
10#include <linux/mount.h>
11#include <linux/fs.h>
12#include <linux/nsproxy.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 *next_slave(struct mount *p)
28{
29 return list_entry(p->mnt_slave.next, struct mount, mnt_slave);
30}
31
32static struct mount *get_peer_under_root(struct mount *mnt,
33 struct mnt_namespace *ns,
34 const struct path *root)
35{
36 struct mount *m = mnt;
37
38 do {
39
40 if (m->mnt_ns == ns && is_path_reachable(m, m->mnt.mnt_root, root))
41 return m;
42
43 m = next_peer(m);
44 } while (m != mnt);
45
46 return NULL;
47}
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53
54
55int get_dominating_id(struct mount *mnt, const struct path *root)
56{
57 struct mount *m;
58
59 for (m = mnt->mnt_master; m != NULL; m = m->mnt_master) {
60 struct mount *d = get_peer_under_root(m, mnt->mnt_ns, root);
61 if (d)
62 return d->mnt_group_id;
63 }
64
65 return 0;
66}
67
68static int do_make_slave(struct mount *mnt)
69{
70 struct mount *peer_mnt = mnt, *master = mnt->mnt_master;
71 struct mount *slave_mnt;
72
73
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76
77
78 while ((peer_mnt = next_peer(peer_mnt)) != mnt &&
79 peer_mnt->mnt.mnt_root != mnt->mnt.mnt_root) ;
80
81 if (peer_mnt == mnt) {
82 peer_mnt = next_peer(mnt);
83 if (peer_mnt == mnt)
84 peer_mnt = NULL;
85 }
86 if (mnt->mnt_group_id && IS_MNT_SHARED(mnt) &&
87 list_empty(&mnt->mnt_share))
88 mnt_release_group_id(mnt);
89
90 list_del_init(&mnt->mnt_share);
91 mnt->mnt_group_id = 0;
92
93 if (peer_mnt)
94 master = peer_mnt;
95
96 if (master) {
97 list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave)
98 slave_mnt->mnt_master = master;
99 list_move(&mnt->mnt_slave, &master->mnt_slave_list);
100 list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev);
101 INIT_LIST_HEAD(&mnt->mnt_slave_list);
102 } else {
103 struct list_head *p = &mnt->mnt_slave_list;
104 while (!list_empty(p)) {
105 slave_mnt = list_first_entry(p,
106 struct mount, mnt_slave);
107 list_del_init(&slave_mnt->mnt_slave);
108 slave_mnt->mnt_master = NULL;
109 }
110 }
111 mnt->mnt_master = master;
112 CLEAR_MNT_SHARED(mnt);
113 return 0;
114}
115
116
117
118
119void change_mnt_propagation(struct mount *mnt, int type)
120{
121 if (type == MS_SHARED) {
122 set_mnt_shared(mnt);
123 return;
124 }
125 do_make_slave(mnt);
126 if (type != MS_SLAVE) {
127 list_del_init(&mnt->mnt_slave);
128 mnt->mnt_master = NULL;
129 if (type == MS_UNBINDABLE)
130 mnt->mnt.mnt_flags |= MNT_UNBINDABLE;
131 else
132 mnt->mnt.mnt_flags &= ~MNT_UNBINDABLE;
133 }
134}
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145
146static struct mount *propagation_next(struct mount *m,
147 struct mount *origin)
148{
149
150 if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
151 return first_slave(m);
152
153 while (1) {
154 struct mount *master = m->mnt_master;
155
156 if (master == origin->mnt_master) {
157 struct mount *next = next_peer(m);
158 return (next == origin) ? NULL : next;
159 } else if (m->mnt_slave.next != &master->mnt_slave_list)
160 return next_slave(m);
161
162
163 m = master;
164 }
165}
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175
176static struct mount *get_source(struct mount *dest,
177 struct mount *last_dest,
178 struct mount *last_src,
179 int *type)
180{
181 struct mount *p_last_src = NULL;
182 struct mount *p_last_dest = NULL;
183
184 while (last_dest != dest->mnt_master) {
185 p_last_dest = last_dest;
186 p_last_src = last_src;
187 last_dest = last_dest->mnt_master;
188 last_src = last_src->mnt_master;
189 }
190
191 if (p_last_dest) {
192 do {
193 p_last_dest = next_peer(p_last_dest);
194 } while (IS_MNT_NEW(p_last_dest));
195
196 if (dest == p_last_dest) {
197 *type = CL_MAKE_SHARED;
198 return p_last_src;
199 }
200 }
201
202 *type = CL_SLAVE;
203
204 if (IS_MNT_SHARED(dest))
205 *type |= CL_MAKE_SHARED;
206 return last_src;
207}
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221
222int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp,
223 struct mount *source_mnt, struct list_head *tree_list)
224{
225 struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
226 struct mount *m, *child;
227 int ret = 0;
228 struct mount *prev_dest_mnt = dest_mnt;
229 struct mount *prev_src_mnt = source_mnt;
230 LIST_HEAD(tmp_list);
231
232 for (m = propagation_next(dest_mnt, dest_mnt); m;
233 m = propagation_next(m, dest_mnt)) {
234 int type;
235 struct mount *source;
236
237 if (IS_MNT_NEW(m))
238 continue;
239
240 source = get_source(m, prev_dest_mnt, prev_src_mnt, &type);
241
242
243 if (m->mnt_ns->user_ns != user_ns)
244 type |= CL_UNPRIVILEGED;
245
246 child = copy_tree(source, source->mnt.mnt_root, type);
247 if (IS_ERR(child)) {
248 ret = PTR_ERR(child);
249 list_splice(tree_list, tmp_list.prev);
250 goto out;
251 }
252
253 if (is_subdir(dest_mp->m_dentry, m->mnt.mnt_root)) {
254 mnt_set_mountpoint(m, dest_mp, child);
255 list_add_tail(&child->mnt_hash, tree_list);
256 } else {
257
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259
260
261 list_add_tail(&child->mnt_hash, &tmp_list);
262 }
263 prev_dest_mnt = m;
264 prev_src_mnt = child;
265 }
266out:
267 br_write_lock(&vfsmount_lock);
268 while (!list_empty(&tmp_list)) {
269 child = list_first_entry(&tmp_list, struct mount, mnt_hash);
270 umount_tree(child, 0);
271 }
272 br_write_unlock(&vfsmount_lock);
273 return ret;
274}
275
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278
279static inline int do_refcount_check(struct mount *mnt, int count)
280{
281 int mycount = mnt_get_count(mnt) - mnt->mnt_ghosts;
282 return (mycount > count);
283}
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295int propagate_mount_busy(struct mount *mnt, int refcnt)
296{
297 struct mount *m, *child;
298 struct mount *parent = mnt->mnt_parent;
299 int ret = 0;
300
301 if (mnt == parent)
302 return do_refcount_check(mnt, refcnt);
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308
309 if (!list_empty(&mnt->mnt_mounts) || do_refcount_check(mnt, refcnt))
310 return 1;
311
312 for (m = propagation_next(parent, parent); m;
313 m = propagation_next(m, parent)) {
314 child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint, 0);
315 if (child && list_empty(&child->mnt_mounts) &&
316 (ret = do_refcount_check(child, 1)))
317 break;
318 }
319 return ret;
320}
321
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325
326static void __propagate_umount(struct mount *mnt)
327{
328 struct mount *parent = mnt->mnt_parent;
329 struct mount *m;
330
331 BUG_ON(parent == mnt);
332
333 for (m = propagation_next(parent, parent); m;
334 m = propagation_next(m, parent)) {
335
336 struct mount *child = __lookup_mnt(&m->mnt,
337 mnt->mnt_mountpoint, 0);
338
339
340
341
342 if (child && list_empty(&child->mnt_mounts))
343 list_move_tail(&child->mnt_hash, &mnt->mnt_hash);
344 }
345}
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353
354int propagate_umount(struct list_head *list)
355{
356 struct mount *mnt;
357
358 list_for_each_entry(mnt, list, mnt_hash)
359 __propagate_umount(mnt);
360 return 0;
361}
362