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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/namespace.c | |
3 | * | |
4 | * (C) Copyright Al Viro 2000, 2001 | |
5 | * Released under GPL v2. | |
6 | * | |
7 | * Based on code from fs/super.c, copyright Linus Torvalds and others. | |
8 | * Heavily rewritten. | |
9 | */ | |
10 | ||
11 | #include <linux/config.h> | |
12 | #include <linux/syscalls.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/sched.h> | |
15 | #include <linux/smp_lock.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/quotaops.h> | |
18 | #include <linux/acct.h> | |
16f7e0fe | 19 | #include <linux/capability.h> |
1da177e4 LT |
20 | #include <linux/module.h> |
21 | #include <linux/seq_file.h> | |
22 | #include <linux/namespace.h> | |
23 | #include <linux/namei.h> | |
24 | #include <linux/security.h> | |
25 | #include <linux/mount.h> | |
26 | #include <asm/uaccess.h> | |
27 | #include <asm/unistd.h> | |
07b20889 | 28 | #include "pnode.h" |
1da177e4 LT |
29 | |
30 | extern int __init init_rootfs(void); | |
31 | ||
32 | #ifdef CONFIG_SYSFS | |
33 | extern int __init sysfs_init(void); | |
34 | #else | |
35 | static inline int sysfs_init(void) | |
36 | { | |
37 | return 0; | |
38 | } | |
39 | #endif | |
40 | ||
41 | /* spinlock for vfsmount related operations, inplace of dcache_lock */ | |
5addc5dd AV |
42 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); |
43 | ||
44 | static int event; | |
1da177e4 LT |
45 | |
46 | static struct list_head *mount_hashtable; | |
6c231b7b | 47 | static int hash_mask __read_mostly, hash_bits __read_mostly; |
b58fed8b | 48 | static kmem_cache_t *mnt_cache; |
390c6843 | 49 | static struct rw_semaphore namespace_sem; |
1da177e4 LT |
50 | |
51 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) | |
52 | { | |
b58fed8b RP |
53 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
54 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
1da177e4 LT |
55 | tmp = tmp + (tmp >> hash_bits); |
56 | return tmp & hash_mask; | |
57 | } | |
58 | ||
59 | struct vfsmount *alloc_vfsmnt(const char *name) | |
60 | { | |
b58fed8b | 61 | struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL); |
1da177e4 LT |
62 | if (mnt) { |
63 | memset(mnt, 0, sizeof(struct vfsmount)); | |
b58fed8b | 64 | atomic_set(&mnt->mnt_count, 1); |
1da177e4 LT |
65 | INIT_LIST_HEAD(&mnt->mnt_hash); |
66 | INIT_LIST_HEAD(&mnt->mnt_child); | |
67 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
68 | INIT_LIST_HEAD(&mnt->mnt_list); | |
55e700b9 | 69 | INIT_LIST_HEAD(&mnt->mnt_expire); |
03e06e68 | 70 | INIT_LIST_HEAD(&mnt->mnt_share); |
a58b0eb8 RP |
71 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
72 | INIT_LIST_HEAD(&mnt->mnt_slave); | |
1da177e4 | 73 | if (name) { |
b58fed8b | 74 | int size = strlen(name) + 1; |
1da177e4 LT |
75 | char *newname = kmalloc(size, GFP_KERNEL); |
76 | if (newname) { | |
77 | memcpy(newname, name, size); | |
78 | mnt->mnt_devname = newname; | |
79 | } | |
80 | } | |
81 | } | |
82 | return mnt; | |
83 | } | |
84 | ||
85 | void free_vfsmnt(struct vfsmount *mnt) | |
86 | { | |
87 | kfree(mnt->mnt_devname); | |
88 | kmem_cache_free(mnt_cache, mnt); | |
89 | } | |
90 | ||
91 | /* | |
a05964f3 RP |
92 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
93 | * @dir. If @dir is set return the first mount else return the last mount. | |
1da177e4 | 94 | */ |
a05964f3 RP |
95 | struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
96 | int dir) | |
1da177e4 | 97 | { |
b58fed8b RP |
98 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
99 | struct list_head *tmp = head; | |
1da177e4 LT |
100 | struct vfsmount *p, *found = NULL; |
101 | ||
1da177e4 | 102 | for (;;) { |
a05964f3 | 103 | tmp = dir ? tmp->next : tmp->prev; |
1da177e4 LT |
104 | p = NULL; |
105 | if (tmp == head) | |
106 | break; | |
107 | p = list_entry(tmp, struct vfsmount, mnt_hash); | |
108 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { | |
a05964f3 | 109 | found = p; |
1da177e4 LT |
110 | break; |
111 | } | |
112 | } | |
1da177e4 LT |
113 | return found; |
114 | } | |
115 | ||
a05964f3 RP |
116 | /* |
117 | * lookup_mnt increments the ref count before returning | |
118 | * the vfsmount struct. | |
119 | */ | |
120 | struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) | |
121 | { | |
122 | struct vfsmount *child_mnt; | |
123 | spin_lock(&vfsmount_lock); | |
124 | if ((child_mnt = __lookup_mnt(mnt, dentry, 1))) | |
125 | mntget(child_mnt); | |
126 | spin_unlock(&vfsmount_lock); | |
127 | return child_mnt; | |
128 | } | |
129 | ||
1da177e4 LT |
130 | static inline int check_mnt(struct vfsmount *mnt) |
131 | { | |
132 | return mnt->mnt_namespace == current->namespace; | |
133 | } | |
134 | ||
5addc5dd AV |
135 | static void touch_namespace(struct namespace *ns) |
136 | { | |
137 | if (ns) { | |
138 | ns->event = ++event; | |
139 | wake_up_interruptible(&ns->poll); | |
140 | } | |
141 | } | |
142 | ||
143 | static void __touch_namespace(struct namespace *ns) | |
144 | { | |
145 | if (ns && ns->event != event) { | |
146 | ns->event = event; | |
147 | wake_up_interruptible(&ns->poll); | |
148 | } | |
149 | } | |
150 | ||
1da177e4 LT |
151 | static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) |
152 | { | |
153 | old_nd->dentry = mnt->mnt_mountpoint; | |
154 | old_nd->mnt = mnt->mnt_parent; | |
155 | mnt->mnt_parent = mnt; | |
156 | mnt->mnt_mountpoint = mnt->mnt_root; | |
157 | list_del_init(&mnt->mnt_child); | |
158 | list_del_init(&mnt->mnt_hash); | |
159 | old_nd->dentry->d_mounted--; | |
160 | } | |
161 | ||
b90fa9ae RP |
162 | void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, |
163 | struct vfsmount *child_mnt) | |
164 | { | |
165 | child_mnt->mnt_parent = mntget(mnt); | |
166 | child_mnt->mnt_mountpoint = dget(dentry); | |
167 | dentry->d_mounted++; | |
168 | } | |
169 | ||
1da177e4 LT |
170 | static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) |
171 | { | |
b90fa9ae RP |
172 | mnt_set_mountpoint(nd->mnt, nd->dentry, mnt); |
173 | list_add_tail(&mnt->mnt_hash, mount_hashtable + | |
174 | hash(nd->mnt, nd->dentry)); | |
1da177e4 | 175 | list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts); |
b90fa9ae RP |
176 | } |
177 | ||
178 | /* | |
179 | * the caller must hold vfsmount_lock | |
180 | */ | |
181 | static void commit_tree(struct vfsmount *mnt) | |
182 | { | |
183 | struct vfsmount *parent = mnt->mnt_parent; | |
184 | struct vfsmount *m; | |
185 | LIST_HEAD(head); | |
186 | struct namespace *n = parent->mnt_namespace; | |
187 | ||
188 | BUG_ON(parent == mnt); | |
189 | ||
190 | list_add_tail(&head, &mnt->mnt_list); | |
191 | list_for_each_entry(m, &head, mnt_list) | |
192 | m->mnt_namespace = n; | |
193 | list_splice(&head, n->list.prev); | |
194 | ||
195 | list_add_tail(&mnt->mnt_hash, mount_hashtable + | |
196 | hash(parent, mnt->mnt_mountpoint)); | |
197 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); | |
198 | touch_namespace(n); | |
1da177e4 LT |
199 | } |
200 | ||
201 | static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) | |
202 | { | |
203 | struct list_head *next = p->mnt_mounts.next; | |
204 | if (next == &p->mnt_mounts) { | |
205 | while (1) { | |
206 | if (p == root) | |
207 | return NULL; | |
208 | next = p->mnt_child.next; | |
209 | if (next != &p->mnt_parent->mnt_mounts) | |
210 | break; | |
211 | p = p->mnt_parent; | |
212 | } | |
213 | } | |
214 | return list_entry(next, struct vfsmount, mnt_child); | |
215 | } | |
216 | ||
9676f0c6 RP |
217 | static struct vfsmount *skip_mnt_tree(struct vfsmount *p) |
218 | { | |
219 | struct list_head *prev = p->mnt_mounts.prev; | |
220 | while (prev != &p->mnt_mounts) { | |
221 | p = list_entry(prev, struct vfsmount, mnt_child); | |
222 | prev = p->mnt_mounts.prev; | |
223 | } | |
224 | return p; | |
225 | } | |
226 | ||
36341f64 RP |
227 | static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, |
228 | int flag) | |
1da177e4 LT |
229 | { |
230 | struct super_block *sb = old->mnt_sb; | |
231 | struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); | |
232 | ||
233 | if (mnt) { | |
234 | mnt->mnt_flags = old->mnt_flags; | |
235 | atomic_inc(&sb->s_active); | |
236 | mnt->mnt_sb = sb; | |
237 | mnt->mnt_root = dget(root); | |
238 | mnt->mnt_mountpoint = mnt->mnt_root; | |
239 | mnt->mnt_parent = mnt; | |
b90fa9ae | 240 | |
5afe0022 RP |
241 | if (flag & CL_SLAVE) { |
242 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); | |
243 | mnt->mnt_master = old; | |
244 | CLEAR_MNT_SHARED(mnt); | |
245 | } else { | |
246 | if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old)) | |
247 | list_add(&mnt->mnt_share, &old->mnt_share); | |
248 | if (IS_MNT_SLAVE(old)) | |
249 | list_add(&mnt->mnt_slave, &old->mnt_slave); | |
250 | mnt->mnt_master = old->mnt_master; | |
251 | } | |
b90fa9ae RP |
252 | if (flag & CL_MAKE_SHARED) |
253 | set_mnt_shared(mnt); | |
1da177e4 LT |
254 | |
255 | /* stick the duplicate mount on the same expiry list | |
256 | * as the original if that was on one */ | |
36341f64 RP |
257 | if (flag & CL_EXPIRE) { |
258 | spin_lock(&vfsmount_lock); | |
259 | if (!list_empty(&old->mnt_expire)) | |
260 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
261 | spin_unlock(&vfsmount_lock); | |
262 | } | |
1da177e4 LT |
263 | } |
264 | return mnt; | |
265 | } | |
266 | ||
7b7b1ace | 267 | static inline void __mntput(struct vfsmount *mnt) |
1da177e4 LT |
268 | { |
269 | struct super_block *sb = mnt->mnt_sb; | |
270 | dput(mnt->mnt_root); | |
271 | free_vfsmnt(mnt); | |
272 | deactivate_super(sb); | |
273 | } | |
274 | ||
7b7b1ace AV |
275 | void mntput_no_expire(struct vfsmount *mnt) |
276 | { | |
277 | repeat: | |
278 | if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { | |
279 | if (likely(!mnt->mnt_pinned)) { | |
280 | spin_unlock(&vfsmount_lock); | |
281 | __mntput(mnt); | |
282 | return; | |
283 | } | |
284 | atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); | |
285 | mnt->mnt_pinned = 0; | |
286 | spin_unlock(&vfsmount_lock); | |
287 | acct_auto_close_mnt(mnt); | |
288 | security_sb_umount_close(mnt); | |
289 | goto repeat; | |
290 | } | |
291 | } | |
292 | ||
293 | EXPORT_SYMBOL(mntput_no_expire); | |
294 | ||
295 | void mnt_pin(struct vfsmount *mnt) | |
296 | { | |
297 | spin_lock(&vfsmount_lock); | |
298 | mnt->mnt_pinned++; | |
299 | spin_unlock(&vfsmount_lock); | |
300 | } | |
301 | ||
302 | EXPORT_SYMBOL(mnt_pin); | |
303 | ||
304 | void mnt_unpin(struct vfsmount *mnt) | |
305 | { | |
306 | spin_lock(&vfsmount_lock); | |
307 | if (mnt->mnt_pinned) { | |
308 | atomic_inc(&mnt->mnt_count); | |
309 | mnt->mnt_pinned--; | |
310 | } | |
311 | spin_unlock(&vfsmount_lock); | |
312 | } | |
313 | ||
314 | EXPORT_SYMBOL(mnt_unpin); | |
1da177e4 LT |
315 | |
316 | /* iterator */ | |
317 | static void *m_start(struct seq_file *m, loff_t *pos) | |
318 | { | |
319 | struct namespace *n = m->private; | |
320 | struct list_head *p; | |
321 | loff_t l = *pos; | |
322 | ||
390c6843 | 323 | down_read(&namespace_sem); |
1da177e4 LT |
324 | list_for_each(p, &n->list) |
325 | if (!l--) | |
326 | return list_entry(p, struct vfsmount, mnt_list); | |
327 | return NULL; | |
328 | } | |
329 | ||
330 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
331 | { | |
332 | struct namespace *n = m->private; | |
333 | struct list_head *p = ((struct vfsmount *)v)->mnt_list.next; | |
334 | (*pos)++; | |
b58fed8b | 335 | return p == &n->list ? NULL : list_entry(p, struct vfsmount, mnt_list); |
1da177e4 LT |
336 | } |
337 | ||
338 | static void m_stop(struct seq_file *m, void *v) | |
339 | { | |
390c6843 | 340 | up_read(&namespace_sem); |
1da177e4 LT |
341 | } |
342 | ||
343 | static inline void mangle(struct seq_file *m, const char *s) | |
344 | { | |
345 | seq_escape(m, s, " \t\n\\"); | |
346 | } | |
347 | ||
348 | static int show_vfsmnt(struct seq_file *m, void *v) | |
349 | { | |
350 | struct vfsmount *mnt = v; | |
351 | int err = 0; | |
352 | static struct proc_fs_info { | |
353 | int flag; | |
354 | char *str; | |
355 | } fs_info[] = { | |
356 | { MS_SYNCHRONOUS, ",sync" }, | |
357 | { MS_DIRSYNC, ",dirsync" }, | |
358 | { MS_MANDLOCK, ",mand" }, | |
1da177e4 LT |
359 | { 0, NULL } |
360 | }; | |
361 | static struct proc_fs_info mnt_info[] = { | |
362 | { MNT_NOSUID, ",nosuid" }, | |
363 | { MNT_NODEV, ",nodev" }, | |
364 | { MNT_NOEXEC, ",noexec" }, | |
fc33a7bb CH |
365 | { MNT_NOATIME, ",noatime" }, |
366 | { MNT_NODIRATIME, ",nodiratime" }, | |
1da177e4 LT |
367 | { 0, NULL } |
368 | }; | |
369 | struct proc_fs_info *fs_infop; | |
370 | ||
371 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
372 | seq_putc(m, ' '); | |
373 | seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); | |
374 | seq_putc(m, ' '); | |
375 | mangle(m, mnt->mnt_sb->s_type->name); | |
376 | seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); | |
377 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { | |
378 | if (mnt->mnt_sb->s_flags & fs_infop->flag) | |
379 | seq_puts(m, fs_infop->str); | |
380 | } | |
381 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { | |
382 | if (mnt->mnt_flags & fs_infop->flag) | |
383 | seq_puts(m, fs_infop->str); | |
384 | } | |
385 | if (mnt->mnt_sb->s_op->show_options) | |
386 | err = mnt->mnt_sb->s_op->show_options(m, mnt); | |
387 | seq_puts(m, " 0 0\n"); | |
388 | return err; | |
389 | } | |
390 | ||
391 | struct seq_operations mounts_op = { | |
392 | .start = m_start, | |
393 | .next = m_next, | |
394 | .stop = m_stop, | |
395 | .show = show_vfsmnt | |
396 | }; | |
397 | ||
398 | /** | |
399 | * may_umount_tree - check if a mount tree is busy | |
400 | * @mnt: root of mount tree | |
401 | * | |
402 | * This is called to check if a tree of mounts has any | |
403 | * open files, pwds, chroots or sub mounts that are | |
404 | * busy. | |
405 | */ | |
406 | int may_umount_tree(struct vfsmount *mnt) | |
407 | { | |
36341f64 RP |
408 | int actual_refs = 0; |
409 | int minimum_refs = 0; | |
410 | struct vfsmount *p; | |
1da177e4 LT |
411 | |
412 | spin_lock(&vfsmount_lock); | |
36341f64 | 413 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
1da177e4 LT |
414 | actual_refs += atomic_read(&p->mnt_count); |
415 | minimum_refs += 2; | |
1da177e4 LT |
416 | } |
417 | spin_unlock(&vfsmount_lock); | |
418 | ||
419 | if (actual_refs > minimum_refs) | |
420 | return -EBUSY; | |
421 | ||
422 | return 0; | |
423 | } | |
424 | ||
425 | EXPORT_SYMBOL(may_umount_tree); | |
426 | ||
427 | /** | |
428 | * may_umount - check if a mount point is busy | |
429 | * @mnt: root of mount | |
430 | * | |
431 | * This is called to check if a mount point has any | |
432 | * open files, pwds, chroots or sub mounts. If the | |
433 | * mount has sub mounts this will return busy | |
434 | * regardless of whether the sub mounts are busy. | |
435 | * | |
436 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
437 | * give false negatives. The main reason why it's here is that we need | |
438 | * a non-destructive way to look for easily umountable filesystems. | |
439 | */ | |
440 | int may_umount(struct vfsmount *mnt) | |
441 | { | |
a05964f3 RP |
442 | int ret = 0; |
443 | spin_lock(&vfsmount_lock); | |
444 | if (propagate_mount_busy(mnt, 2)) | |
445 | ret = -EBUSY; | |
446 | spin_unlock(&vfsmount_lock); | |
447 | return ret; | |
1da177e4 LT |
448 | } |
449 | ||
450 | EXPORT_SYMBOL(may_umount); | |
451 | ||
b90fa9ae | 452 | void release_mounts(struct list_head *head) |
70fbcdf4 RP |
453 | { |
454 | struct vfsmount *mnt; | |
bf066c7d | 455 | while (!list_empty(head)) { |
70fbcdf4 RP |
456 | mnt = list_entry(head->next, struct vfsmount, mnt_hash); |
457 | list_del_init(&mnt->mnt_hash); | |
458 | if (mnt->mnt_parent != mnt) { | |
459 | struct dentry *dentry; | |
460 | struct vfsmount *m; | |
461 | spin_lock(&vfsmount_lock); | |
462 | dentry = mnt->mnt_mountpoint; | |
463 | m = mnt->mnt_parent; | |
464 | mnt->mnt_mountpoint = mnt->mnt_root; | |
465 | mnt->mnt_parent = mnt; | |
466 | spin_unlock(&vfsmount_lock); | |
467 | dput(dentry); | |
468 | mntput(m); | |
469 | } | |
470 | mntput(mnt); | |
471 | } | |
472 | } | |
473 | ||
a05964f3 | 474 | void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) |
1da177e4 LT |
475 | { |
476 | struct vfsmount *p; | |
1da177e4 LT |
477 | |
478 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
70fbcdf4 RP |
479 | list_del(&p->mnt_hash); |
480 | list_add(&p->mnt_hash, kill); | |
1da177e4 LT |
481 | } |
482 | ||
a05964f3 RP |
483 | if (propagate) |
484 | propagate_umount(kill); | |
485 | ||
70fbcdf4 RP |
486 | list_for_each_entry(p, kill, mnt_hash) { |
487 | list_del_init(&p->mnt_expire); | |
488 | list_del_init(&p->mnt_list); | |
489 | __touch_namespace(p->mnt_namespace); | |
490 | p->mnt_namespace = NULL; | |
491 | list_del_init(&p->mnt_child); | |
492 | if (p->mnt_parent != p) | |
493 | mnt->mnt_mountpoint->d_mounted--; | |
a05964f3 | 494 | change_mnt_propagation(p, MS_PRIVATE); |
1da177e4 LT |
495 | } |
496 | } | |
497 | ||
498 | static int do_umount(struct vfsmount *mnt, int flags) | |
499 | { | |
b58fed8b | 500 | struct super_block *sb = mnt->mnt_sb; |
1da177e4 | 501 | int retval; |
70fbcdf4 | 502 | LIST_HEAD(umount_list); |
1da177e4 LT |
503 | |
504 | retval = security_sb_umount(mnt, flags); | |
505 | if (retval) | |
506 | return retval; | |
507 | ||
508 | /* | |
509 | * Allow userspace to request a mountpoint be expired rather than | |
510 | * unmounting unconditionally. Unmount only happens if: | |
511 | * (1) the mark is already set (the mark is cleared by mntput()) | |
512 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
513 | */ | |
514 | if (flags & MNT_EXPIRE) { | |
515 | if (mnt == current->fs->rootmnt || | |
516 | flags & (MNT_FORCE | MNT_DETACH)) | |
517 | return -EINVAL; | |
518 | ||
519 | if (atomic_read(&mnt->mnt_count) != 2) | |
520 | return -EBUSY; | |
521 | ||
522 | if (!xchg(&mnt->mnt_expiry_mark, 1)) | |
523 | return -EAGAIN; | |
524 | } | |
525 | ||
526 | /* | |
527 | * If we may have to abort operations to get out of this | |
528 | * mount, and they will themselves hold resources we must | |
529 | * allow the fs to do things. In the Unix tradition of | |
530 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
531 | * might fail to complete on the first run through as other tasks | |
532 | * must return, and the like. Thats for the mount program to worry | |
533 | * about for the moment. | |
534 | */ | |
535 | ||
536 | lock_kernel(); | |
b58fed8b | 537 | if ((flags & MNT_FORCE) && sb->s_op->umount_begin) |
1da177e4 LT |
538 | sb->s_op->umount_begin(sb); |
539 | unlock_kernel(); | |
540 | ||
541 | /* | |
542 | * No sense to grab the lock for this test, but test itself looks | |
543 | * somewhat bogus. Suggestions for better replacement? | |
544 | * Ho-hum... In principle, we might treat that as umount + switch | |
545 | * to rootfs. GC would eventually take care of the old vfsmount. | |
546 | * Actually it makes sense, especially if rootfs would contain a | |
547 | * /reboot - static binary that would close all descriptors and | |
548 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
549 | */ | |
550 | if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) { | |
551 | /* | |
552 | * Special case for "unmounting" root ... | |
553 | * we just try to remount it readonly. | |
554 | */ | |
555 | down_write(&sb->s_umount); | |
556 | if (!(sb->s_flags & MS_RDONLY)) { | |
557 | lock_kernel(); | |
558 | DQUOT_OFF(sb); | |
559 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); | |
560 | unlock_kernel(); | |
561 | } | |
562 | up_write(&sb->s_umount); | |
563 | return retval; | |
564 | } | |
565 | ||
390c6843 | 566 | down_write(&namespace_sem); |
1da177e4 | 567 | spin_lock(&vfsmount_lock); |
5addc5dd | 568 | event++; |
1da177e4 | 569 | |
1da177e4 | 570 | retval = -EBUSY; |
a05964f3 | 571 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
1da177e4 | 572 | if (!list_empty(&mnt->mnt_list)) |
a05964f3 | 573 | umount_tree(mnt, 1, &umount_list); |
1da177e4 LT |
574 | retval = 0; |
575 | } | |
576 | spin_unlock(&vfsmount_lock); | |
577 | if (retval) | |
578 | security_sb_umount_busy(mnt); | |
390c6843 | 579 | up_write(&namespace_sem); |
70fbcdf4 | 580 | release_mounts(&umount_list); |
1da177e4 LT |
581 | return retval; |
582 | } | |
583 | ||
584 | /* | |
585 | * Now umount can handle mount points as well as block devices. | |
586 | * This is important for filesystems which use unnamed block devices. | |
587 | * | |
588 | * We now support a flag for forced unmount like the other 'big iron' | |
589 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD | |
590 | */ | |
591 | ||
592 | asmlinkage long sys_umount(char __user * name, int flags) | |
593 | { | |
594 | struct nameidata nd; | |
595 | int retval; | |
596 | ||
597 | retval = __user_walk(name, LOOKUP_FOLLOW, &nd); | |
598 | if (retval) | |
599 | goto out; | |
600 | retval = -EINVAL; | |
601 | if (nd.dentry != nd.mnt->mnt_root) | |
602 | goto dput_and_out; | |
603 | if (!check_mnt(nd.mnt)) | |
604 | goto dput_and_out; | |
605 | ||
606 | retval = -EPERM; | |
607 | if (!capable(CAP_SYS_ADMIN)) | |
608 | goto dput_and_out; | |
609 | ||
610 | retval = do_umount(nd.mnt, flags); | |
611 | dput_and_out: | |
612 | path_release_on_umount(&nd); | |
613 | out: | |
614 | return retval; | |
615 | } | |
616 | ||
617 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT | |
618 | ||
619 | /* | |
b58fed8b | 620 | * The 2.0 compatible umount. No flags. |
1da177e4 | 621 | */ |
1da177e4 LT |
622 | asmlinkage long sys_oldumount(char __user * name) |
623 | { | |
b58fed8b | 624 | return sys_umount(name, 0); |
1da177e4 LT |
625 | } |
626 | ||
627 | #endif | |
628 | ||
629 | static int mount_is_safe(struct nameidata *nd) | |
630 | { | |
631 | if (capable(CAP_SYS_ADMIN)) | |
632 | return 0; | |
633 | return -EPERM; | |
634 | #ifdef notyet | |
635 | if (S_ISLNK(nd->dentry->d_inode->i_mode)) | |
636 | return -EPERM; | |
637 | if (nd->dentry->d_inode->i_mode & S_ISVTX) { | |
638 | if (current->uid != nd->dentry->d_inode->i_uid) | |
639 | return -EPERM; | |
640 | } | |
e4543edd | 641 | if (vfs_permission(nd, MAY_WRITE)) |
1da177e4 LT |
642 | return -EPERM; |
643 | return 0; | |
644 | #endif | |
645 | } | |
646 | ||
b58fed8b | 647 | static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry) |
1da177e4 LT |
648 | { |
649 | while (1) { | |
650 | if (d == dentry) | |
651 | return 1; | |
652 | if (d == NULL || d == d->d_parent) | |
653 | return 0; | |
654 | d = d->d_parent; | |
655 | } | |
656 | } | |
657 | ||
b90fa9ae | 658 | struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, |
36341f64 | 659 | int flag) |
1da177e4 LT |
660 | { |
661 | struct vfsmount *res, *p, *q, *r, *s; | |
1da177e4 LT |
662 | struct nameidata nd; |
663 | ||
9676f0c6 RP |
664 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) |
665 | return NULL; | |
666 | ||
36341f64 | 667 | res = q = clone_mnt(mnt, dentry, flag); |
1da177e4 LT |
668 | if (!q) |
669 | goto Enomem; | |
670 | q->mnt_mountpoint = mnt->mnt_mountpoint; | |
671 | ||
672 | p = mnt; | |
fdadd65f | 673 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
1da177e4 LT |
674 | if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry)) |
675 | continue; | |
676 | ||
677 | for (s = r; s; s = next_mnt(s, r)) { | |
9676f0c6 RP |
678 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { |
679 | s = skip_mnt_tree(s); | |
680 | continue; | |
681 | } | |
1da177e4 LT |
682 | while (p != s->mnt_parent) { |
683 | p = p->mnt_parent; | |
684 | q = q->mnt_parent; | |
685 | } | |
686 | p = s; | |
687 | nd.mnt = q; | |
688 | nd.dentry = p->mnt_mountpoint; | |
36341f64 | 689 | q = clone_mnt(p, p->mnt_root, flag); |
1da177e4 LT |
690 | if (!q) |
691 | goto Enomem; | |
692 | spin_lock(&vfsmount_lock); | |
693 | list_add_tail(&q->mnt_list, &res->mnt_list); | |
694 | attach_mnt(q, &nd); | |
695 | spin_unlock(&vfsmount_lock); | |
696 | } | |
697 | } | |
698 | return res; | |
b58fed8b | 699 | Enomem: |
1da177e4 | 700 | if (res) { |
70fbcdf4 | 701 | LIST_HEAD(umount_list); |
1da177e4 | 702 | spin_lock(&vfsmount_lock); |
a05964f3 | 703 | umount_tree(res, 0, &umount_list); |
1da177e4 | 704 | spin_unlock(&vfsmount_lock); |
70fbcdf4 | 705 | release_mounts(&umount_list); |
1da177e4 LT |
706 | } |
707 | return NULL; | |
708 | } | |
709 | ||
b90fa9ae RP |
710 | /* |
711 | * @source_mnt : mount tree to be attached | |
21444403 RP |
712 | * @nd : place the mount tree @source_mnt is attached |
713 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
714 | * store the parent mount and mountpoint dentry. | |
715 | * (done when source_mnt is moved) | |
b90fa9ae RP |
716 | * |
717 | * NOTE: in the table below explains the semantics when a source mount | |
718 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
719 | * --------------------------------------------------------------------------- |
720 | * | BIND MOUNT OPERATION | | |
721 | * |************************************************************************** | |
722 | * | source-->| shared | private | slave | unbindable | | |
723 | * | dest | | | | | | |
724 | * | | | | | | | | |
725 | * | v | | | | | | |
726 | * |************************************************************************** | |
727 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
728 | * | | | | | | | |
729 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
730 | * *************************************************************************** | |
b90fa9ae RP |
731 | * A bind operation clones the source mount and mounts the clone on the |
732 | * destination mount. | |
733 | * | |
734 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
735 | * tree of the destination mount and the cloned mount is added to | |
736 | * the peer group of the source mount. | |
737 | * (+) the cloned mount is created under the destination mount and is marked | |
738 | * as shared. The cloned mount is added to the peer group of the source | |
739 | * mount. | |
5afe0022 RP |
740 | * (+++) the mount is propagated to all the mounts in the propagation tree |
741 | * of the destination mount and the cloned mount is made slave | |
742 | * of the same master as that of the source mount. The cloned mount | |
743 | * is marked as 'shared and slave'. | |
744 | * (*) the cloned mount is made a slave of the same master as that of the | |
745 | * source mount. | |
746 | * | |
9676f0c6 RP |
747 | * --------------------------------------------------------------------------- |
748 | * | MOVE MOUNT OPERATION | | |
749 | * |************************************************************************** | |
750 | * | source-->| shared | private | slave | unbindable | | |
751 | * | dest | | | | | | |
752 | * | | | | | | | | |
753 | * | v | | | | | | |
754 | * |************************************************************************** | |
755 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
756 | * | | | | | | | |
757 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
758 | * *************************************************************************** | |
5afe0022 RP |
759 | * |
760 | * (+) the mount is moved to the destination. And is then propagated to | |
761 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 762 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
763 | * (+++) the mount is moved to the destination and is then propagated to |
764 | * all the mounts belonging to the destination mount's propagation tree. | |
765 | * the mount is marked as 'shared and slave'. | |
766 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
767 | * |
768 | * if the source mount is a tree, the operations explained above is | |
769 | * applied to each mount in the tree. | |
770 | * Must be called without spinlocks held, since this function can sleep | |
771 | * in allocations. | |
772 | */ | |
773 | static int attach_recursive_mnt(struct vfsmount *source_mnt, | |
21444403 | 774 | struct nameidata *nd, struct nameidata *parent_nd) |
b90fa9ae RP |
775 | { |
776 | LIST_HEAD(tree_list); | |
777 | struct vfsmount *dest_mnt = nd->mnt; | |
778 | struct dentry *dest_dentry = nd->dentry; | |
779 | struct vfsmount *child, *p; | |
780 | ||
781 | if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) | |
782 | return -EINVAL; | |
783 | ||
784 | if (IS_MNT_SHARED(dest_mnt)) { | |
785 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) | |
786 | set_mnt_shared(p); | |
787 | } | |
788 | ||
789 | spin_lock(&vfsmount_lock); | |
21444403 RP |
790 | if (parent_nd) { |
791 | detach_mnt(source_mnt, parent_nd); | |
792 | attach_mnt(source_mnt, nd); | |
793 | touch_namespace(current->namespace); | |
794 | } else { | |
795 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); | |
796 | commit_tree(source_mnt); | |
797 | } | |
b90fa9ae RP |
798 | |
799 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { | |
800 | list_del_init(&child->mnt_hash); | |
801 | commit_tree(child); | |
802 | } | |
803 | spin_unlock(&vfsmount_lock); | |
804 | return 0; | |
805 | } | |
806 | ||
1da177e4 LT |
807 | static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) |
808 | { | |
809 | int err; | |
810 | if (mnt->mnt_sb->s_flags & MS_NOUSER) | |
811 | return -EINVAL; | |
812 | ||
813 | if (S_ISDIR(nd->dentry->d_inode->i_mode) != | |
814 | S_ISDIR(mnt->mnt_root->d_inode->i_mode)) | |
815 | return -ENOTDIR; | |
816 | ||
817 | err = -ENOENT; | |
1b1dcc1b | 818 | mutex_lock(&nd->dentry->d_inode->i_mutex); |
1da177e4 LT |
819 | if (IS_DEADDIR(nd->dentry->d_inode)) |
820 | goto out_unlock; | |
821 | ||
822 | err = security_sb_check_sb(mnt, nd); | |
823 | if (err) | |
824 | goto out_unlock; | |
825 | ||
826 | err = -ENOENT; | |
b90fa9ae | 827 | if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) |
21444403 | 828 | err = attach_recursive_mnt(mnt, nd, NULL); |
1da177e4 | 829 | out_unlock: |
1b1dcc1b | 830 | mutex_unlock(&nd->dentry->d_inode->i_mutex); |
1da177e4 LT |
831 | if (!err) |
832 | security_sb_post_addmount(mnt, nd); | |
833 | return err; | |
834 | } | |
835 | ||
07b20889 RP |
836 | /* |
837 | * recursively change the type of the mountpoint. | |
838 | */ | |
839 | static int do_change_type(struct nameidata *nd, int flag) | |
840 | { | |
841 | struct vfsmount *m, *mnt = nd->mnt; | |
842 | int recurse = flag & MS_REC; | |
843 | int type = flag & ~MS_REC; | |
844 | ||
845 | if (nd->dentry != nd->mnt->mnt_root) | |
846 | return -EINVAL; | |
847 | ||
848 | down_write(&namespace_sem); | |
849 | spin_lock(&vfsmount_lock); | |
850 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) | |
851 | change_mnt_propagation(m, type); | |
852 | spin_unlock(&vfsmount_lock); | |
853 | up_write(&namespace_sem); | |
854 | return 0; | |
855 | } | |
856 | ||
1da177e4 LT |
857 | /* |
858 | * do loopback mount. | |
859 | */ | |
860 | static int do_loopback(struct nameidata *nd, char *old_name, int recurse) | |
861 | { | |
862 | struct nameidata old_nd; | |
863 | struct vfsmount *mnt = NULL; | |
864 | int err = mount_is_safe(nd); | |
865 | if (err) | |
866 | return err; | |
867 | if (!old_name || !*old_name) | |
868 | return -EINVAL; | |
869 | err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); | |
870 | if (err) | |
871 | return err; | |
872 | ||
390c6843 | 873 | down_write(&namespace_sem); |
1da177e4 | 874 | err = -EINVAL; |
9676f0c6 RP |
875 | if (IS_MNT_UNBINDABLE(old_nd.mnt)) |
876 | goto out; | |
877 | ||
ccd48bc7 AV |
878 | if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) |
879 | goto out; | |
1da177e4 | 880 | |
ccd48bc7 AV |
881 | err = -ENOMEM; |
882 | if (recurse) | |
36341f64 | 883 | mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0); |
ccd48bc7 | 884 | else |
36341f64 | 885 | mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0); |
ccd48bc7 AV |
886 | |
887 | if (!mnt) | |
888 | goto out; | |
889 | ||
ccd48bc7 AV |
890 | err = graft_tree(mnt, nd); |
891 | if (err) { | |
70fbcdf4 | 892 | LIST_HEAD(umount_list); |
1da177e4 | 893 | spin_lock(&vfsmount_lock); |
a05964f3 | 894 | umount_tree(mnt, 0, &umount_list); |
1da177e4 | 895 | spin_unlock(&vfsmount_lock); |
70fbcdf4 | 896 | release_mounts(&umount_list); |
5b83d2c5 | 897 | } |
1da177e4 | 898 | |
ccd48bc7 | 899 | out: |
390c6843 | 900 | up_write(&namespace_sem); |
1da177e4 LT |
901 | path_release(&old_nd); |
902 | return err; | |
903 | } | |
904 | ||
905 | /* | |
906 | * change filesystem flags. dir should be a physical root of filesystem. | |
907 | * If you've mounted a non-root directory somewhere and want to do remount | |
908 | * on it - tough luck. | |
909 | */ | |
1da177e4 LT |
910 | static int do_remount(struct nameidata *nd, int flags, int mnt_flags, |
911 | void *data) | |
912 | { | |
913 | int err; | |
b58fed8b | 914 | struct super_block *sb = nd->mnt->mnt_sb; |
1da177e4 LT |
915 | |
916 | if (!capable(CAP_SYS_ADMIN)) | |
917 | return -EPERM; | |
918 | ||
919 | if (!check_mnt(nd->mnt)) | |
920 | return -EINVAL; | |
921 | ||
922 | if (nd->dentry != nd->mnt->mnt_root) | |
923 | return -EINVAL; | |
924 | ||
925 | down_write(&sb->s_umount); | |
926 | err = do_remount_sb(sb, flags, data, 0); | |
927 | if (!err) | |
b58fed8b | 928 | nd->mnt->mnt_flags = mnt_flags; |
1da177e4 LT |
929 | up_write(&sb->s_umount); |
930 | if (!err) | |
931 | security_sb_post_remount(nd->mnt, flags, data); | |
932 | return err; | |
933 | } | |
934 | ||
9676f0c6 RP |
935 | static inline int tree_contains_unbindable(struct vfsmount *mnt) |
936 | { | |
937 | struct vfsmount *p; | |
938 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
939 | if (IS_MNT_UNBINDABLE(p)) | |
940 | return 1; | |
941 | } | |
942 | return 0; | |
943 | } | |
944 | ||
1da177e4 LT |
945 | static int do_move_mount(struct nameidata *nd, char *old_name) |
946 | { | |
947 | struct nameidata old_nd, parent_nd; | |
948 | struct vfsmount *p; | |
949 | int err = 0; | |
950 | if (!capable(CAP_SYS_ADMIN)) | |
951 | return -EPERM; | |
952 | if (!old_name || !*old_name) | |
953 | return -EINVAL; | |
954 | err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); | |
955 | if (err) | |
956 | return err; | |
957 | ||
390c6843 | 958 | down_write(&namespace_sem); |
b58fed8b | 959 | while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
1da177e4 LT |
960 | ; |
961 | err = -EINVAL; | |
962 | if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) | |
963 | goto out; | |
964 | ||
965 | err = -ENOENT; | |
1b1dcc1b | 966 | mutex_lock(&nd->dentry->d_inode->i_mutex); |
1da177e4 LT |
967 | if (IS_DEADDIR(nd->dentry->d_inode)) |
968 | goto out1; | |
969 | ||
1da177e4 | 970 | if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) |
21444403 | 971 | goto out1; |
1da177e4 LT |
972 | |
973 | err = -EINVAL; | |
974 | if (old_nd.dentry != old_nd.mnt->mnt_root) | |
21444403 | 975 | goto out1; |
1da177e4 LT |
976 | |
977 | if (old_nd.mnt == old_nd.mnt->mnt_parent) | |
21444403 | 978 | goto out1; |
1da177e4 LT |
979 | |
980 | if (S_ISDIR(nd->dentry->d_inode->i_mode) != | |
981 | S_ISDIR(old_nd.dentry->d_inode->i_mode)) | |
21444403 RP |
982 | goto out1; |
983 | /* | |
984 | * Don't move a mount residing in a shared parent. | |
985 | */ | |
986 | if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent)) | |
987 | goto out1; | |
9676f0c6 RP |
988 | /* |
989 | * Don't move a mount tree containing unbindable mounts to a destination | |
990 | * mount which is shared. | |
991 | */ | |
992 | if (IS_MNT_SHARED(nd->mnt) && tree_contains_unbindable(old_nd.mnt)) | |
993 | goto out1; | |
1da177e4 | 994 | err = -ELOOP; |
b58fed8b | 995 | for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent) |
1da177e4 | 996 | if (p == old_nd.mnt) |
21444403 | 997 | goto out1; |
1da177e4 | 998 | |
21444403 RP |
999 | if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd))) |
1000 | goto out1; | |
1da177e4 | 1001 | |
21444403 | 1002 | spin_lock(&vfsmount_lock); |
1da177e4 LT |
1003 | /* if the mount is moved, it should no longer be expire |
1004 | * automatically */ | |
55e700b9 | 1005 | list_del_init(&old_nd.mnt->mnt_expire); |
1da177e4 LT |
1006 | spin_unlock(&vfsmount_lock); |
1007 | out1: | |
1b1dcc1b | 1008 | mutex_unlock(&nd->dentry->d_inode->i_mutex); |
1da177e4 | 1009 | out: |
390c6843 | 1010 | up_write(&namespace_sem); |
1da177e4 LT |
1011 | if (!err) |
1012 | path_release(&parent_nd); | |
1013 | path_release(&old_nd); | |
1014 | return err; | |
1015 | } | |
1016 | ||
1017 | /* | |
1018 | * create a new mount for userspace and request it to be added into the | |
1019 | * namespace's tree | |
1020 | */ | |
1021 | static int do_new_mount(struct nameidata *nd, char *type, int flags, | |
1022 | int mnt_flags, char *name, void *data) | |
1023 | { | |
1024 | struct vfsmount *mnt; | |
1025 | ||
1026 | if (!type || !memchr(type, 0, PAGE_SIZE)) | |
1027 | return -EINVAL; | |
1028 | ||
1029 | /* we need capabilities... */ | |
1030 | if (!capable(CAP_SYS_ADMIN)) | |
1031 | return -EPERM; | |
1032 | ||
1033 | mnt = do_kern_mount(type, flags, name, data); | |
1034 | if (IS_ERR(mnt)) | |
1035 | return PTR_ERR(mnt); | |
1036 | ||
1037 | return do_add_mount(mnt, nd, mnt_flags, NULL); | |
1038 | } | |
1039 | ||
1040 | /* | |
1041 | * add a mount into a namespace's mount tree | |
1042 | * - provide the option of adding the new mount to an expiration list | |
1043 | */ | |
1044 | int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, | |
1045 | int mnt_flags, struct list_head *fslist) | |
1046 | { | |
1047 | int err; | |
1048 | ||
390c6843 | 1049 | down_write(&namespace_sem); |
1da177e4 | 1050 | /* Something was mounted here while we slept */ |
b58fed8b | 1051 | while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
1da177e4 LT |
1052 | ; |
1053 | err = -EINVAL; | |
1054 | if (!check_mnt(nd->mnt)) | |
1055 | goto unlock; | |
1056 | ||
1057 | /* Refuse the same filesystem on the same mount point */ | |
1058 | err = -EBUSY; | |
1059 | if (nd->mnt->mnt_sb == newmnt->mnt_sb && | |
1060 | nd->mnt->mnt_root == nd->dentry) | |
1061 | goto unlock; | |
1062 | ||
1063 | err = -EINVAL; | |
1064 | if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) | |
1065 | goto unlock; | |
1066 | ||
1067 | newmnt->mnt_flags = mnt_flags; | |
5b83d2c5 RP |
1068 | if ((err = graft_tree(newmnt, nd))) |
1069 | goto unlock; | |
1da177e4 | 1070 | |
5b83d2c5 | 1071 | if (fslist) { |
1da177e4 LT |
1072 | /* add to the specified expiration list */ |
1073 | spin_lock(&vfsmount_lock); | |
55e700b9 | 1074 | list_add_tail(&newmnt->mnt_expire, fslist); |
1da177e4 LT |
1075 | spin_unlock(&vfsmount_lock); |
1076 | } | |
390c6843 | 1077 | up_write(&namespace_sem); |
5b83d2c5 | 1078 | return 0; |
1da177e4 LT |
1079 | |
1080 | unlock: | |
390c6843 | 1081 | up_write(&namespace_sem); |
1da177e4 LT |
1082 | mntput(newmnt); |
1083 | return err; | |
1084 | } | |
1085 | ||
1086 | EXPORT_SYMBOL_GPL(do_add_mount); | |
1087 | ||
70fbcdf4 RP |
1088 | static void expire_mount(struct vfsmount *mnt, struct list_head *mounts, |
1089 | struct list_head *umounts) | |
24ca2af1 MS |
1090 | { |
1091 | spin_lock(&vfsmount_lock); | |
1092 | ||
ed42c879 MS |
1093 | /* |
1094 | * Check if mount is still attached, if not, let whoever holds it deal | |
1095 | * with the sucker | |
1096 | */ | |
1097 | if (mnt->mnt_parent == mnt) { | |
1098 | spin_unlock(&vfsmount_lock); | |
1099 | return; | |
1100 | } | |
1101 | ||
24ca2af1 MS |
1102 | /* |
1103 | * Check that it is still dead: the count should now be 2 - as | |
1104 | * contributed by the vfsmount parent and the mntget above | |
1105 | */ | |
a05964f3 | 1106 | if (!propagate_mount_busy(mnt, 2)) { |
24ca2af1 | 1107 | /* delete from the namespace */ |
5addc5dd | 1108 | touch_namespace(mnt->mnt_namespace); |
24ca2af1 | 1109 | list_del_init(&mnt->mnt_list); |
ac081153 | 1110 | mnt->mnt_namespace = NULL; |
a05964f3 | 1111 | umount_tree(mnt, 1, umounts); |
24ca2af1 | 1112 | spin_unlock(&vfsmount_lock); |
24ca2af1 MS |
1113 | } else { |
1114 | /* | |
1115 | * Someone brought it back to life whilst we didn't have any | |
1116 | * locks held so return it to the expiration list | |
1117 | */ | |
55e700b9 | 1118 | list_add_tail(&mnt->mnt_expire, mounts); |
24ca2af1 MS |
1119 | spin_unlock(&vfsmount_lock); |
1120 | } | |
1121 | } | |
1122 | ||
1da177e4 LT |
1123 | /* |
1124 | * process a list of expirable mountpoints with the intent of discarding any | |
1125 | * mountpoints that aren't in use and haven't been touched since last we came | |
1126 | * here | |
1127 | */ | |
1128 | void mark_mounts_for_expiry(struct list_head *mounts) | |
1129 | { | |
1130 | struct namespace *namespace; | |
1131 | struct vfsmount *mnt, *next; | |
1132 | LIST_HEAD(graveyard); | |
1133 | ||
1134 | if (list_empty(mounts)) | |
1135 | return; | |
1136 | ||
1137 | spin_lock(&vfsmount_lock); | |
1138 | ||
1139 | /* extract from the expiration list every vfsmount that matches the | |
1140 | * following criteria: | |
1141 | * - only referenced by its parent vfsmount | |
1142 | * - still marked for expiry (marked on the last call here; marks are | |
1143 | * cleared by mntput()) | |
1144 | */ | |
55e700b9 | 1145 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
1da177e4 LT |
1146 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
1147 | atomic_read(&mnt->mnt_count) != 1) | |
1148 | continue; | |
1149 | ||
1150 | mntget(mnt); | |
55e700b9 | 1151 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 LT |
1152 | } |
1153 | ||
1154 | /* | |
1155 | * go through the vfsmounts we've just consigned to the graveyard to | |
1156 | * - check that they're still dead | |
1157 | * - delete the vfsmount from the appropriate namespace under lock | |
1158 | * - dispose of the corpse | |
1159 | */ | |
1160 | while (!list_empty(&graveyard)) { | |
70fbcdf4 | 1161 | LIST_HEAD(umounts); |
55e700b9 MS |
1162 | mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire); |
1163 | list_del_init(&mnt->mnt_expire); | |
1da177e4 LT |
1164 | |
1165 | /* don't do anything if the namespace is dead - all the | |
1166 | * vfsmounts from it are going away anyway */ | |
1167 | namespace = mnt->mnt_namespace; | |
1ce88cf4 | 1168 | if (!namespace || !namespace->root) |
1da177e4 LT |
1169 | continue; |
1170 | get_namespace(namespace); | |
1171 | ||
1172 | spin_unlock(&vfsmount_lock); | |
390c6843 | 1173 | down_write(&namespace_sem); |
70fbcdf4 | 1174 | expire_mount(mnt, mounts, &umounts); |
390c6843 | 1175 | up_write(&namespace_sem); |
70fbcdf4 | 1176 | release_mounts(&umounts); |
1da177e4 LT |
1177 | mntput(mnt); |
1178 | put_namespace(namespace); | |
1da177e4 LT |
1179 | spin_lock(&vfsmount_lock); |
1180 | } | |
1181 | ||
1182 | spin_unlock(&vfsmount_lock); | |
1183 | } | |
1184 | ||
1185 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
1186 | ||
1187 | /* | |
1188 | * Some copy_from_user() implementations do not return the exact number of | |
1189 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. | |
1190 | * Note that this function differs from copy_from_user() in that it will oops | |
1191 | * on bad values of `to', rather than returning a short copy. | |
1192 | */ | |
b58fed8b RP |
1193 | static long exact_copy_from_user(void *to, const void __user * from, |
1194 | unsigned long n) | |
1da177e4 LT |
1195 | { |
1196 | char *t = to; | |
1197 | const char __user *f = from; | |
1198 | char c; | |
1199 | ||
1200 | if (!access_ok(VERIFY_READ, from, n)) | |
1201 | return n; | |
1202 | ||
1203 | while (n) { | |
1204 | if (__get_user(c, f)) { | |
1205 | memset(t, 0, n); | |
1206 | break; | |
1207 | } | |
1208 | *t++ = c; | |
1209 | f++; | |
1210 | n--; | |
1211 | } | |
1212 | return n; | |
1213 | } | |
1214 | ||
b58fed8b | 1215 | int copy_mount_options(const void __user * data, unsigned long *where) |
1da177e4 LT |
1216 | { |
1217 | int i; | |
1218 | unsigned long page; | |
1219 | unsigned long size; | |
b58fed8b | 1220 | |
1da177e4 LT |
1221 | *where = 0; |
1222 | if (!data) | |
1223 | return 0; | |
1224 | ||
1225 | if (!(page = __get_free_page(GFP_KERNEL))) | |
1226 | return -ENOMEM; | |
1227 | ||
1228 | /* We only care that *some* data at the address the user | |
1229 | * gave us is valid. Just in case, we'll zero | |
1230 | * the remainder of the page. | |
1231 | */ | |
1232 | /* copy_from_user cannot cross TASK_SIZE ! */ | |
1233 | size = TASK_SIZE - (unsigned long)data; | |
1234 | if (size > PAGE_SIZE) | |
1235 | size = PAGE_SIZE; | |
1236 | ||
1237 | i = size - exact_copy_from_user((void *)page, data, size); | |
1238 | if (!i) { | |
b58fed8b | 1239 | free_page(page); |
1da177e4 LT |
1240 | return -EFAULT; |
1241 | } | |
1242 | if (i != PAGE_SIZE) | |
1243 | memset((char *)page + i, 0, PAGE_SIZE - i); | |
1244 | *where = page; | |
1245 | return 0; | |
1246 | } | |
1247 | ||
1248 | /* | |
1249 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
1250 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
1251 | * | |
1252 | * data is a (void *) that can point to any structure up to | |
1253 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
1254 | * information (or be NULL). | |
1255 | * | |
1256 | * Pre-0.97 versions of mount() didn't have a flags word. | |
1257 | * When the flags word was introduced its top half was required | |
1258 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
1259 | * Therefore, if this magic number is present, it carries no information | |
1260 | * and must be discarded. | |
1261 | */ | |
b58fed8b | 1262 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
1da177e4 LT |
1263 | unsigned long flags, void *data_page) |
1264 | { | |
1265 | struct nameidata nd; | |
1266 | int retval = 0; | |
1267 | int mnt_flags = 0; | |
1268 | ||
1269 | /* Discard magic */ | |
1270 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
1271 | flags &= ~MS_MGC_MSK; | |
1272 | ||
1273 | /* Basic sanity checks */ | |
1274 | ||
1275 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) | |
1276 | return -EINVAL; | |
1277 | if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) | |
1278 | return -EINVAL; | |
1279 | ||
1280 | if (data_page) | |
1281 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
1282 | ||
1283 | /* Separate the per-mountpoint flags */ | |
1284 | if (flags & MS_NOSUID) | |
1285 | mnt_flags |= MNT_NOSUID; | |
1286 | if (flags & MS_NODEV) | |
1287 | mnt_flags |= MNT_NODEV; | |
1288 | if (flags & MS_NOEXEC) | |
1289 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
1290 | if (flags & MS_NOATIME) |
1291 | mnt_flags |= MNT_NOATIME; | |
1292 | if (flags & MS_NODIRATIME) | |
1293 | mnt_flags |= MNT_NODIRATIME; | |
1294 | ||
1295 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | | |
1296 | MS_NOATIME | MS_NODIRATIME); | |
1da177e4 LT |
1297 | |
1298 | /* ... and get the mountpoint */ | |
1299 | retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); | |
1300 | if (retval) | |
1301 | return retval; | |
1302 | ||
1303 | retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page); | |
1304 | if (retval) | |
1305 | goto dput_out; | |
1306 | ||
1307 | if (flags & MS_REMOUNT) | |
1308 | retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, | |
1309 | data_page); | |
1310 | else if (flags & MS_BIND) | |
1311 | retval = do_loopback(&nd, dev_name, flags & MS_REC); | |
9676f0c6 | 1312 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
07b20889 | 1313 | retval = do_change_type(&nd, flags); |
1da177e4 LT |
1314 | else if (flags & MS_MOVE) |
1315 | retval = do_move_mount(&nd, dev_name); | |
1316 | else | |
1317 | retval = do_new_mount(&nd, type_page, flags, mnt_flags, | |
1318 | dev_name, data_page); | |
1319 | dput_out: | |
1320 | path_release(&nd); | |
1321 | return retval; | |
1322 | } | |
1323 | ||
1324 | int copy_namespace(int flags, struct task_struct *tsk) | |
1325 | { | |
1326 | struct namespace *namespace = tsk->namespace; | |
1327 | struct namespace *new_ns; | |
1328 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL; | |
1329 | struct fs_struct *fs = tsk->fs; | |
1330 | struct vfsmount *p, *q; | |
1331 | ||
1332 | if (!namespace) | |
1333 | return 0; | |
1334 | ||
1335 | get_namespace(namespace); | |
1336 | ||
1337 | if (!(flags & CLONE_NEWNS)) | |
1338 | return 0; | |
1339 | ||
1340 | if (!capable(CAP_SYS_ADMIN)) { | |
1341 | put_namespace(namespace); | |
1342 | return -EPERM; | |
1343 | } | |
1344 | ||
1345 | new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL); | |
1346 | if (!new_ns) | |
1347 | goto out; | |
1348 | ||
1349 | atomic_set(&new_ns->count, 1); | |
1da177e4 | 1350 | INIT_LIST_HEAD(&new_ns->list); |
5addc5dd AV |
1351 | init_waitqueue_head(&new_ns->poll); |
1352 | new_ns->event = 0; | |
1da177e4 | 1353 | |
390c6843 | 1354 | down_write(&namespace_sem); |
1da177e4 | 1355 | /* First pass: copy the tree topology */ |
36341f64 | 1356 | new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root, |
9676f0c6 | 1357 | CL_COPY_ALL | CL_EXPIRE); |
1da177e4 | 1358 | if (!new_ns->root) { |
390c6843 | 1359 | up_write(&namespace_sem); |
1da177e4 LT |
1360 | kfree(new_ns); |
1361 | goto out; | |
1362 | } | |
1363 | spin_lock(&vfsmount_lock); | |
1364 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); | |
1365 | spin_unlock(&vfsmount_lock); | |
1366 | ||
1367 | /* | |
1368 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
1369 | * as belonging to new namespace. We have already acquired a private | |
1370 | * fs_struct, so tsk->fs->lock is not needed. | |
1371 | */ | |
1372 | p = namespace->root; | |
1373 | q = new_ns->root; | |
1374 | while (p) { | |
1375 | q->mnt_namespace = new_ns; | |
1376 | if (fs) { | |
1377 | if (p == fs->rootmnt) { | |
1378 | rootmnt = p; | |
1379 | fs->rootmnt = mntget(q); | |
1380 | } | |
1381 | if (p == fs->pwdmnt) { | |
1382 | pwdmnt = p; | |
1383 | fs->pwdmnt = mntget(q); | |
1384 | } | |
1385 | if (p == fs->altrootmnt) { | |
1386 | altrootmnt = p; | |
1387 | fs->altrootmnt = mntget(q); | |
1388 | } | |
1389 | } | |
1390 | p = next_mnt(p, namespace->root); | |
1391 | q = next_mnt(q, new_ns->root); | |
1392 | } | |
390c6843 | 1393 | up_write(&namespace_sem); |
1da177e4 LT |
1394 | |
1395 | tsk->namespace = new_ns; | |
1396 | ||
1397 | if (rootmnt) | |
1398 | mntput(rootmnt); | |
1399 | if (pwdmnt) | |
1400 | mntput(pwdmnt); | |
1401 | if (altrootmnt) | |
1402 | mntput(altrootmnt); | |
1403 | ||
1404 | put_namespace(namespace); | |
1405 | return 0; | |
1406 | ||
1407 | out: | |
1408 | put_namespace(namespace); | |
1409 | return -ENOMEM; | |
1410 | } | |
1411 | ||
1412 | asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name, | |
1413 | char __user * type, unsigned long flags, | |
1414 | void __user * data) | |
1415 | { | |
1416 | int retval; | |
1417 | unsigned long data_page; | |
1418 | unsigned long type_page; | |
1419 | unsigned long dev_page; | |
1420 | char *dir_page; | |
1421 | ||
b58fed8b | 1422 | retval = copy_mount_options(type, &type_page); |
1da177e4 LT |
1423 | if (retval < 0) |
1424 | return retval; | |
1425 | ||
1426 | dir_page = getname(dir_name); | |
1427 | retval = PTR_ERR(dir_page); | |
1428 | if (IS_ERR(dir_page)) | |
1429 | goto out1; | |
1430 | ||
b58fed8b | 1431 | retval = copy_mount_options(dev_name, &dev_page); |
1da177e4 LT |
1432 | if (retval < 0) |
1433 | goto out2; | |
1434 | ||
b58fed8b | 1435 | retval = copy_mount_options(data, &data_page); |
1da177e4 LT |
1436 | if (retval < 0) |
1437 | goto out3; | |
1438 | ||
1439 | lock_kernel(); | |
b58fed8b RP |
1440 | retval = do_mount((char *)dev_page, dir_page, (char *)type_page, |
1441 | flags, (void *)data_page); | |
1da177e4 LT |
1442 | unlock_kernel(); |
1443 | free_page(data_page); | |
1444 | ||
1445 | out3: | |
1446 | free_page(dev_page); | |
1447 | out2: | |
1448 | putname(dir_page); | |
1449 | out1: | |
1450 | free_page(type_page); | |
1451 | return retval; | |
1452 | } | |
1453 | ||
1454 | /* | |
1455 | * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. | |
1456 | * It can block. Requires the big lock held. | |
1457 | */ | |
1458 | void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt, | |
1459 | struct dentry *dentry) | |
1460 | { | |
1461 | struct dentry *old_root; | |
1462 | struct vfsmount *old_rootmnt; | |
1463 | write_lock(&fs->lock); | |
1464 | old_root = fs->root; | |
1465 | old_rootmnt = fs->rootmnt; | |
1466 | fs->rootmnt = mntget(mnt); | |
1467 | fs->root = dget(dentry); | |
1468 | write_unlock(&fs->lock); | |
1469 | if (old_root) { | |
1470 | dput(old_root); | |
1471 | mntput(old_rootmnt); | |
1472 | } | |
1473 | } | |
1474 | ||
1475 | /* | |
1476 | * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. | |
1477 | * It can block. Requires the big lock held. | |
1478 | */ | |
1479 | void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, | |
1480 | struct dentry *dentry) | |
1481 | { | |
1482 | struct dentry *old_pwd; | |
1483 | struct vfsmount *old_pwdmnt; | |
1484 | ||
1485 | write_lock(&fs->lock); | |
1486 | old_pwd = fs->pwd; | |
1487 | old_pwdmnt = fs->pwdmnt; | |
1488 | fs->pwdmnt = mntget(mnt); | |
1489 | fs->pwd = dget(dentry); | |
1490 | write_unlock(&fs->lock); | |
1491 | ||
1492 | if (old_pwd) { | |
1493 | dput(old_pwd); | |
1494 | mntput(old_pwdmnt); | |
1495 | } | |
1496 | } | |
1497 | ||
1498 | static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) | |
1499 | { | |
1500 | struct task_struct *g, *p; | |
1501 | struct fs_struct *fs; | |
1502 | ||
1503 | read_lock(&tasklist_lock); | |
1504 | do_each_thread(g, p) { | |
1505 | task_lock(p); | |
1506 | fs = p->fs; | |
1507 | if (fs) { | |
1508 | atomic_inc(&fs->count); | |
1509 | task_unlock(p); | |
b58fed8b RP |
1510 | if (fs->root == old_nd->dentry |
1511 | && fs->rootmnt == old_nd->mnt) | |
1da177e4 | 1512 | set_fs_root(fs, new_nd->mnt, new_nd->dentry); |
b58fed8b RP |
1513 | if (fs->pwd == old_nd->dentry |
1514 | && fs->pwdmnt == old_nd->mnt) | |
1da177e4 LT |
1515 | set_fs_pwd(fs, new_nd->mnt, new_nd->dentry); |
1516 | put_fs_struct(fs); | |
1517 | } else | |
1518 | task_unlock(p); | |
1519 | } while_each_thread(g, p); | |
1520 | read_unlock(&tasklist_lock); | |
1521 | } | |
1522 | ||
1523 | /* | |
1524 | * pivot_root Semantics: | |
1525 | * Moves the root file system of the current process to the directory put_old, | |
1526 | * makes new_root as the new root file system of the current process, and sets | |
1527 | * root/cwd of all processes which had them on the current root to new_root. | |
1528 | * | |
1529 | * Restrictions: | |
1530 | * The new_root and put_old must be directories, and must not be on the | |
1531 | * same file system as the current process root. The put_old must be | |
1532 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
1533 | * pointed to by put_old must yield the same directory as new_root. No other | |
1534 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
1535 | * | |
4a0d11fa NB |
1536 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
1537 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives | |
1538 | * in this situation. | |
1539 | * | |
1da177e4 LT |
1540 | * Notes: |
1541 | * - we don't move root/cwd if they are not at the root (reason: if something | |
1542 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
1543 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
1544 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
1545 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
1546 | * first. | |
1547 | */ | |
b58fed8b RP |
1548 | asmlinkage long sys_pivot_root(const char __user * new_root, |
1549 | const char __user * put_old) | |
1da177e4 LT |
1550 | { |
1551 | struct vfsmount *tmp; | |
1552 | struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; | |
1553 | int error; | |
1554 | ||
1555 | if (!capable(CAP_SYS_ADMIN)) | |
1556 | return -EPERM; | |
1557 | ||
1558 | lock_kernel(); | |
1559 | ||
b58fed8b RP |
1560 | error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, |
1561 | &new_nd); | |
1da177e4 LT |
1562 | if (error) |
1563 | goto out0; | |
1564 | error = -EINVAL; | |
1565 | if (!check_mnt(new_nd.mnt)) | |
1566 | goto out1; | |
1567 | ||
b58fed8b | 1568 | error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd); |
1da177e4 LT |
1569 | if (error) |
1570 | goto out1; | |
1571 | ||
1572 | error = security_sb_pivotroot(&old_nd, &new_nd); | |
1573 | if (error) { | |
1574 | path_release(&old_nd); | |
1575 | goto out1; | |
1576 | } | |
1577 | ||
1578 | read_lock(¤t->fs->lock); | |
1579 | user_nd.mnt = mntget(current->fs->rootmnt); | |
1580 | user_nd.dentry = dget(current->fs->root); | |
1581 | read_unlock(¤t->fs->lock); | |
390c6843 | 1582 | down_write(&namespace_sem); |
1b1dcc1b | 1583 | mutex_lock(&old_nd.dentry->d_inode->i_mutex); |
1da177e4 | 1584 | error = -EINVAL; |
21444403 RP |
1585 | if (IS_MNT_SHARED(old_nd.mnt) || |
1586 | IS_MNT_SHARED(new_nd.mnt->mnt_parent) || | |
1587 | IS_MNT_SHARED(user_nd.mnt->mnt_parent)) | |
1588 | goto out2; | |
1da177e4 LT |
1589 | if (!check_mnt(user_nd.mnt)) |
1590 | goto out2; | |
1591 | error = -ENOENT; | |
1592 | if (IS_DEADDIR(new_nd.dentry->d_inode)) | |
1593 | goto out2; | |
1594 | if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry)) | |
1595 | goto out2; | |
1596 | if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry)) | |
1597 | goto out2; | |
1598 | error = -EBUSY; | |
1599 | if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt) | |
1600 | goto out2; /* loop, on the same file system */ | |
1601 | error = -EINVAL; | |
1602 | if (user_nd.mnt->mnt_root != user_nd.dentry) | |
1603 | goto out2; /* not a mountpoint */ | |
0bb6fcc1 MS |
1604 | if (user_nd.mnt->mnt_parent == user_nd.mnt) |
1605 | goto out2; /* not attached */ | |
1da177e4 LT |
1606 | if (new_nd.mnt->mnt_root != new_nd.dentry) |
1607 | goto out2; /* not a mountpoint */ | |
0bb6fcc1 MS |
1608 | if (new_nd.mnt->mnt_parent == new_nd.mnt) |
1609 | goto out2; /* not attached */ | |
1da177e4 LT |
1610 | tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */ |
1611 | spin_lock(&vfsmount_lock); | |
1612 | if (tmp != new_nd.mnt) { | |
1613 | for (;;) { | |
1614 | if (tmp->mnt_parent == tmp) | |
1615 | goto out3; /* already mounted on put_old */ | |
1616 | if (tmp->mnt_parent == new_nd.mnt) | |
1617 | break; | |
1618 | tmp = tmp->mnt_parent; | |
1619 | } | |
1620 | if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry)) | |
1621 | goto out3; | |
1622 | } else if (!is_subdir(old_nd.dentry, new_nd.dentry)) | |
1623 | goto out3; | |
1624 | detach_mnt(new_nd.mnt, &parent_nd); | |
1625 | detach_mnt(user_nd.mnt, &root_parent); | |
1626 | attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ | |
1627 | attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ | |
5addc5dd | 1628 | touch_namespace(current->namespace); |
1da177e4 LT |
1629 | spin_unlock(&vfsmount_lock); |
1630 | chroot_fs_refs(&user_nd, &new_nd); | |
1631 | security_sb_post_pivotroot(&user_nd, &new_nd); | |
1632 | error = 0; | |
1633 | path_release(&root_parent); | |
1634 | path_release(&parent_nd); | |
1635 | out2: | |
1b1dcc1b | 1636 | mutex_unlock(&old_nd.dentry->d_inode->i_mutex); |
390c6843 | 1637 | up_write(&namespace_sem); |
1da177e4 LT |
1638 | path_release(&user_nd); |
1639 | path_release(&old_nd); | |
1640 | out1: | |
1641 | path_release(&new_nd); | |
1642 | out0: | |
1643 | unlock_kernel(); | |
1644 | return error; | |
1645 | out3: | |
1646 | spin_unlock(&vfsmount_lock); | |
1647 | goto out2; | |
1648 | } | |
1649 | ||
1650 | static void __init init_mount_tree(void) | |
1651 | { | |
1652 | struct vfsmount *mnt; | |
1653 | struct namespace *namespace; | |
1654 | struct task_struct *g, *p; | |
1655 | ||
1656 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); | |
1657 | if (IS_ERR(mnt)) | |
1658 | panic("Can't create rootfs"); | |
1659 | namespace = kmalloc(sizeof(*namespace), GFP_KERNEL); | |
1660 | if (!namespace) | |
1661 | panic("Can't allocate initial namespace"); | |
1662 | atomic_set(&namespace->count, 1); | |
1663 | INIT_LIST_HEAD(&namespace->list); | |
5addc5dd AV |
1664 | init_waitqueue_head(&namespace->poll); |
1665 | namespace->event = 0; | |
1da177e4 LT |
1666 | list_add(&mnt->mnt_list, &namespace->list); |
1667 | namespace->root = mnt; | |
1668 | mnt->mnt_namespace = namespace; | |
1669 | ||
1670 | init_task.namespace = namespace; | |
1671 | read_lock(&tasklist_lock); | |
1672 | do_each_thread(g, p) { | |
1673 | get_namespace(namespace); | |
1674 | p->namespace = namespace; | |
1675 | } while_each_thread(g, p); | |
1676 | read_unlock(&tasklist_lock); | |
1677 | ||
1678 | set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root); | |
1679 | set_fs_root(current->fs, namespace->root, namespace->root->mnt_root); | |
1680 | } | |
1681 | ||
1682 | void __init mnt_init(unsigned long mempages) | |
1683 | { | |
1684 | struct list_head *d; | |
1685 | unsigned int nr_hash; | |
1686 | int i; | |
1687 | ||
390c6843 RP |
1688 | init_rwsem(&namespace_sem); |
1689 | ||
1da177e4 | 1690 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), |
b58fed8b | 1691 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL, NULL); |
1da177e4 | 1692 | |
b58fed8b | 1693 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
1da177e4 LT |
1694 | |
1695 | if (!mount_hashtable) | |
1696 | panic("Failed to allocate mount hash table\n"); | |
1697 | ||
1698 | /* | |
1699 | * Find the power-of-two list-heads that can fit into the allocation.. | |
1700 | * We don't guarantee that "sizeof(struct list_head)" is necessarily | |
1701 | * a power-of-two. | |
1702 | */ | |
1703 | nr_hash = PAGE_SIZE / sizeof(struct list_head); | |
1704 | hash_bits = 0; | |
1705 | do { | |
1706 | hash_bits++; | |
1707 | } while ((nr_hash >> hash_bits) != 0); | |
1708 | hash_bits--; | |
1709 | ||
1710 | /* | |
1711 | * Re-calculate the actual number of entries and the mask | |
1712 | * from the number of bits we can fit. | |
1713 | */ | |
1714 | nr_hash = 1UL << hash_bits; | |
b58fed8b | 1715 | hash_mask = nr_hash - 1; |
1da177e4 LT |
1716 | |
1717 | printk("Mount-cache hash table entries: %d\n", nr_hash); | |
1718 | ||
1719 | /* And initialize the newly allocated array */ | |
1720 | d = mount_hashtable; | |
1721 | i = nr_hash; | |
1722 | do { | |
1723 | INIT_LIST_HEAD(d); | |
1724 | d++; | |
1725 | i--; | |
1726 | } while (i); | |
1727 | sysfs_init(); | |
1728 | init_rootfs(); | |
1729 | init_mount_tree(); | |
1730 | } | |
1731 | ||
1732 | void __put_namespace(struct namespace *namespace) | |
1733 | { | |
1ce88cf4 | 1734 | struct vfsmount *root = namespace->root; |
70fbcdf4 | 1735 | LIST_HEAD(umount_list); |
1ce88cf4 MS |
1736 | namespace->root = NULL; |
1737 | spin_unlock(&vfsmount_lock); | |
390c6843 | 1738 | down_write(&namespace_sem); |
1da177e4 | 1739 | spin_lock(&vfsmount_lock); |
a05964f3 | 1740 | umount_tree(root, 0, &umount_list); |
1da177e4 | 1741 | spin_unlock(&vfsmount_lock); |
390c6843 | 1742 | up_write(&namespace_sem); |
70fbcdf4 | 1743 | release_mounts(&umount_list); |
1da177e4 LT |
1744 | kfree(namespace); |
1745 | } |