Commit | Line | Data |
---|---|---|
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 | ||
1da177e4 LT |
11 | #include <linux/syscalls.h> |
12 | #include <linux/slab.h> | |
13 | #include <linux/sched.h> | |
14 | #include <linux/smp_lock.h> | |
15 | #include <linux/init.h> | |
15a67dd8 | 16 | #include <linux/kernel.h> |
1da177e4 LT |
17 | #include <linux/quotaops.h> |
18 | #include <linux/acct.h> | |
16f7e0fe | 19 | #include <linux/capability.h> |
1da177e4 | 20 | #include <linux/module.h> |
f20a9ead | 21 | #include <linux/sysfs.h> |
1da177e4 | 22 | #include <linux/seq_file.h> |
6b3286ed | 23 | #include <linux/mnt_namespace.h> |
1da177e4 LT |
24 | #include <linux/namei.h> |
25 | #include <linux/security.h> | |
26 | #include <linux/mount.h> | |
07f3f05c | 27 | #include <linux/ramfs.h> |
13f14b4d | 28 | #include <linux/log2.h> |
1da177e4 LT |
29 | #include <asm/uaccess.h> |
30 | #include <asm/unistd.h> | |
07b20889 | 31 | #include "pnode.h" |
948730b0 | 32 | #include "internal.h" |
1da177e4 | 33 | |
13f14b4d ED |
34 | #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) |
35 | #define HASH_SIZE (1UL << HASH_SHIFT) | |
36 | ||
1da177e4 | 37 | /* spinlock for vfsmount related operations, inplace of dcache_lock */ |
5addc5dd AV |
38 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); |
39 | ||
40 | static int event; | |
1da177e4 | 41 | |
fa3536cc | 42 | static struct list_head *mount_hashtable __read_mostly; |
e18b890b | 43 | static struct kmem_cache *mnt_cache __read_mostly; |
390c6843 | 44 | static struct rw_semaphore namespace_sem; |
1da177e4 | 45 | |
f87fd4c2 | 46 | /* /sys/fs */ |
00d26666 GKH |
47 | struct kobject *fs_kobj; |
48 | EXPORT_SYMBOL_GPL(fs_kobj); | |
f87fd4c2 | 49 | |
1da177e4 LT |
50 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) |
51 | { | |
b58fed8b RP |
52 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
53 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
13f14b4d ED |
54 | tmp = tmp + (tmp >> HASH_SHIFT); |
55 | return tmp & (HASH_SIZE - 1); | |
1da177e4 LT |
56 | } |
57 | ||
58 | struct vfsmount *alloc_vfsmnt(const char *name) | |
59 | { | |
c3762229 | 60 | struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
1da177e4 | 61 | if (mnt) { |
b58fed8b | 62 | atomic_set(&mnt->mnt_count, 1); |
1da177e4 LT |
63 | INIT_LIST_HEAD(&mnt->mnt_hash); |
64 | INIT_LIST_HEAD(&mnt->mnt_child); | |
65 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
66 | INIT_LIST_HEAD(&mnt->mnt_list); | |
55e700b9 | 67 | INIT_LIST_HEAD(&mnt->mnt_expire); |
03e06e68 | 68 | INIT_LIST_HEAD(&mnt->mnt_share); |
a58b0eb8 RP |
69 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
70 | INIT_LIST_HEAD(&mnt->mnt_slave); | |
1da177e4 | 71 | if (name) { |
b58fed8b | 72 | int size = strlen(name) + 1; |
1da177e4 LT |
73 | char *newname = kmalloc(size, GFP_KERNEL); |
74 | if (newname) { | |
75 | memcpy(newname, name, size); | |
76 | mnt->mnt_devname = newname; | |
77 | } | |
78 | } | |
79 | } | |
80 | return mnt; | |
81 | } | |
82 | ||
454e2398 DH |
83 | int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb) |
84 | { | |
85 | mnt->mnt_sb = sb; | |
86 | mnt->mnt_root = dget(sb->s_root); | |
87 | return 0; | |
88 | } | |
89 | ||
90 | EXPORT_SYMBOL(simple_set_mnt); | |
91 | ||
1da177e4 LT |
92 | void free_vfsmnt(struct vfsmount *mnt) |
93 | { | |
94 | kfree(mnt->mnt_devname); | |
95 | kmem_cache_free(mnt_cache, mnt); | |
96 | } | |
97 | ||
98 | /* | |
a05964f3 RP |
99 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
100 | * @dir. If @dir is set return the first mount else return the last mount. | |
1da177e4 | 101 | */ |
a05964f3 RP |
102 | struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
103 | int dir) | |
1da177e4 | 104 | { |
b58fed8b RP |
105 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
106 | struct list_head *tmp = head; | |
1da177e4 LT |
107 | struct vfsmount *p, *found = NULL; |
108 | ||
1da177e4 | 109 | for (;;) { |
a05964f3 | 110 | tmp = dir ? tmp->next : tmp->prev; |
1da177e4 LT |
111 | p = NULL; |
112 | if (tmp == head) | |
113 | break; | |
114 | p = list_entry(tmp, struct vfsmount, mnt_hash); | |
115 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { | |
a05964f3 | 116 | found = p; |
1da177e4 LT |
117 | break; |
118 | } | |
119 | } | |
1da177e4 LT |
120 | return found; |
121 | } | |
122 | ||
a05964f3 RP |
123 | /* |
124 | * lookup_mnt increments the ref count before returning | |
125 | * the vfsmount struct. | |
126 | */ | |
127 | struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) | |
128 | { | |
129 | struct vfsmount *child_mnt; | |
130 | spin_lock(&vfsmount_lock); | |
131 | if ((child_mnt = __lookup_mnt(mnt, dentry, 1))) | |
132 | mntget(child_mnt); | |
133 | spin_unlock(&vfsmount_lock); | |
134 | return child_mnt; | |
135 | } | |
136 | ||
1da177e4 LT |
137 | static inline int check_mnt(struct vfsmount *mnt) |
138 | { | |
6b3286ed | 139 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
1da177e4 LT |
140 | } |
141 | ||
6b3286ed | 142 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
143 | { |
144 | if (ns) { | |
145 | ns->event = ++event; | |
146 | wake_up_interruptible(&ns->poll); | |
147 | } | |
148 | } | |
149 | ||
6b3286ed | 150 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
151 | { |
152 | if (ns && ns->event != event) { | |
153 | ns->event = event; | |
154 | wake_up_interruptible(&ns->poll); | |
155 | } | |
156 | } | |
157 | ||
1da177e4 LT |
158 | static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) |
159 | { | |
160 | old_nd->dentry = mnt->mnt_mountpoint; | |
161 | old_nd->mnt = mnt->mnt_parent; | |
162 | mnt->mnt_parent = mnt; | |
163 | mnt->mnt_mountpoint = mnt->mnt_root; | |
164 | list_del_init(&mnt->mnt_child); | |
165 | list_del_init(&mnt->mnt_hash); | |
166 | old_nd->dentry->d_mounted--; | |
167 | } | |
168 | ||
b90fa9ae RP |
169 | void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, |
170 | struct vfsmount *child_mnt) | |
171 | { | |
172 | child_mnt->mnt_parent = mntget(mnt); | |
173 | child_mnt->mnt_mountpoint = dget(dentry); | |
174 | dentry->d_mounted++; | |
175 | } | |
176 | ||
1da177e4 LT |
177 | static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) |
178 | { | |
b90fa9ae RP |
179 | mnt_set_mountpoint(nd->mnt, nd->dentry, mnt); |
180 | list_add_tail(&mnt->mnt_hash, mount_hashtable + | |
181 | hash(nd->mnt, nd->dentry)); | |
1da177e4 | 182 | list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts); |
b90fa9ae RP |
183 | } |
184 | ||
185 | /* | |
186 | * the caller must hold vfsmount_lock | |
187 | */ | |
188 | static void commit_tree(struct vfsmount *mnt) | |
189 | { | |
190 | struct vfsmount *parent = mnt->mnt_parent; | |
191 | struct vfsmount *m; | |
192 | LIST_HEAD(head); | |
6b3286ed | 193 | struct mnt_namespace *n = parent->mnt_ns; |
b90fa9ae RP |
194 | |
195 | BUG_ON(parent == mnt); | |
196 | ||
197 | list_add_tail(&head, &mnt->mnt_list); | |
198 | list_for_each_entry(m, &head, mnt_list) | |
6b3286ed | 199 | m->mnt_ns = n; |
b90fa9ae RP |
200 | list_splice(&head, n->list.prev); |
201 | ||
202 | list_add_tail(&mnt->mnt_hash, mount_hashtable + | |
203 | hash(parent, mnt->mnt_mountpoint)); | |
204 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); | |
6b3286ed | 205 | touch_mnt_namespace(n); |
1da177e4 LT |
206 | } |
207 | ||
208 | static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) | |
209 | { | |
210 | struct list_head *next = p->mnt_mounts.next; | |
211 | if (next == &p->mnt_mounts) { | |
212 | while (1) { | |
213 | if (p == root) | |
214 | return NULL; | |
215 | next = p->mnt_child.next; | |
216 | if (next != &p->mnt_parent->mnt_mounts) | |
217 | break; | |
218 | p = p->mnt_parent; | |
219 | } | |
220 | } | |
221 | return list_entry(next, struct vfsmount, mnt_child); | |
222 | } | |
223 | ||
9676f0c6 RP |
224 | static struct vfsmount *skip_mnt_tree(struct vfsmount *p) |
225 | { | |
226 | struct list_head *prev = p->mnt_mounts.prev; | |
227 | while (prev != &p->mnt_mounts) { | |
228 | p = list_entry(prev, struct vfsmount, mnt_child); | |
229 | prev = p->mnt_mounts.prev; | |
230 | } | |
231 | return p; | |
232 | } | |
233 | ||
36341f64 RP |
234 | static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, |
235 | int flag) | |
1da177e4 LT |
236 | { |
237 | struct super_block *sb = old->mnt_sb; | |
238 | struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); | |
239 | ||
240 | if (mnt) { | |
241 | mnt->mnt_flags = old->mnt_flags; | |
242 | atomic_inc(&sb->s_active); | |
243 | mnt->mnt_sb = sb; | |
244 | mnt->mnt_root = dget(root); | |
245 | mnt->mnt_mountpoint = mnt->mnt_root; | |
246 | mnt->mnt_parent = mnt; | |
b90fa9ae | 247 | |
5afe0022 RP |
248 | if (flag & CL_SLAVE) { |
249 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); | |
250 | mnt->mnt_master = old; | |
251 | CLEAR_MNT_SHARED(mnt); | |
8aec0809 | 252 | } else if (!(flag & CL_PRIVATE)) { |
5afe0022 RP |
253 | if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old)) |
254 | list_add(&mnt->mnt_share, &old->mnt_share); | |
255 | if (IS_MNT_SLAVE(old)) | |
256 | list_add(&mnt->mnt_slave, &old->mnt_slave); | |
257 | mnt->mnt_master = old->mnt_master; | |
258 | } | |
b90fa9ae RP |
259 | if (flag & CL_MAKE_SHARED) |
260 | set_mnt_shared(mnt); | |
1da177e4 LT |
261 | |
262 | /* stick the duplicate mount on the same expiry list | |
263 | * as the original if that was on one */ | |
36341f64 RP |
264 | if (flag & CL_EXPIRE) { |
265 | spin_lock(&vfsmount_lock); | |
266 | if (!list_empty(&old->mnt_expire)) | |
267 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
268 | spin_unlock(&vfsmount_lock); | |
269 | } | |
1da177e4 LT |
270 | } |
271 | return mnt; | |
272 | } | |
273 | ||
7b7b1ace | 274 | static inline void __mntput(struct vfsmount *mnt) |
1da177e4 LT |
275 | { |
276 | struct super_block *sb = mnt->mnt_sb; | |
277 | dput(mnt->mnt_root); | |
278 | free_vfsmnt(mnt); | |
279 | deactivate_super(sb); | |
280 | } | |
281 | ||
7b7b1ace AV |
282 | void mntput_no_expire(struct vfsmount *mnt) |
283 | { | |
284 | repeat: | |
285 | if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { | |
286 | if (likely(!mnt->mnt_pinned)) { | |
287 | spin_unlock(&vfsmount_lock); | |
288 | __mntput(mnt); | |
289 | return; | |
290 | } | |
291 | atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); | |
292 | mnt->mnt_pinned = 0; | |
293 | spin_unlock(&vfsmount_lock); | |
294 | acct_auto_close_mnt(mnt); | |
295 | security_sb_umount_close(mnt); | |
296 | goto repeat; | |
297 | } | |
298 | } | |
299 | ||
300 | EXPORT_SYMBOL(mntput_no_expire); | |
301 | ||
302 | void mnt_pin(struct vfsmount *mnt) | |
303 | { | |
304 | spin_lock(&vfsmount_lock); | |
305 | mnt->mnt_pinned++; | |
306 | spin_unlock(&vfsmount_lock); | |
307 | } | |
308 | ||
309 | EXPORT_SYMBOL(mnt_pin); | |
310 | ||
311 | void mnt_unpin(struct vfsmount *mnt) | |
312 | { | |
313 | spin_lock(&vfsmount_lock); | |
314 | if (mnt->mnt_pinned) { | |
315 | atomic_inc(&mnt->mnt_count); | |
316 | mnt->mnt_pinned--; | |
317 | } | |
318 | spin_unlock(&vfsmount_lock); | |
319 | } | |
320 | ||
321 | EXPORT_SYMBOL(mnt_unpin); | |
1da177e4 LT |
322 | |
323 | /* iterator */ | |
324 | static void *m_start(struct seq_file *m, loff_t *pos) | |
325 | { | |
6b3286ed | 326 | struct mnt_namespace *n = m->private; |
1da177e4 | 327 | |
390c6843 | 328 | down_read(&namespace_sem); |
b0765fb8 | 329 | return seq_list_start(&n->list, *pos); |
1da177e4 LT |
330 | } |
331 | ||
332 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
333 | { | |
6b3286ed | 334 | struct mnt_namespace *n = m->private; |
b0765fb8 PE |
335 | |
336 | return seq_list_next(v, &n->list, pos); | |
1da177e4 LT |
337 | } |
338 | ||
339 | static void m_stop(struct seq_file *m, void *v) | |
340 | { | |
390c6843 | 341 | up_read(&namespace_sem); |
1da177e4 LT |
342 | } |
343 | ||
344 | static inline void mangle(struct seq_file *m, const char *s) | |
345 | { | |
346 | seq_escape(m, s, " \t\n\\"); | |
347 | } | |
348 | ||
349 | static int show_vfsmnt(struct seq_file *m, void *v) | |
350 | { | |
b0765fb8 | 351 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
1da177e4 LT |
352 | int err = 0; |
353 | static struct proc_fs_info { | |
354 | int flag; | |
355 | char *str; | |
356 | } fs_info[] = { | |
357 | { MS_SYNCHRONOUS, ",sync" }, | |
358 | { MS_DIRSYNC, ",dirsync" }, | |
359 | { MS_MANDLOCK, ",mand" }, | |
1da177e4 LT |
360 | { 0, NULL } |
361 | }; | |
362 | static struct proc_fs_info mnt_info[] = { | |
363 | { MNT_NOSUID, ",nosuid" }, | |
364 | { MNT_NODEV, ",nodev" }, | |
365 | { MNT_NOEXEC, ",noexec" }, | |
fc33a7bb CH |
366 | { MNT_NOATIME, ",noatime" }, |
367 | { MNT_NODIRATIME, ",nodiratime" }, | |
47ae32d6 | 368 | { MNT_RELATIME, ",relatime" }, |
1da177e4 LT |
369 | { 0, NULL } |
370 | }; | |
371 | struct proc_fs_info *fs_infop; | |
372 | ||
373 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
374 | seq_putc(m, ' '); | |
375 | seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); | |
376 | seq_putc(m, ' '); | |
377 | mangle(m, mnt->mnt_sb->s_type->name); | |
79c0b2df MS |
378 | if (mnt->mnt_sb->s_subtype && mnt->mnt_sb->s_subtype[0]) { |
379 | seq_putc(m, '.'); | |
380 | mangle(m, mnt->mnt_sb->s_subtype); | |
381 | } | |
1da177e4 LT |
382 | seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); |
383 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { | |
384 | if (mnt->mnt_sb->s_flags & fs_infop->flag) | |
385 | seq_puts(m, fs_infop->str); | |
386 | } | |
387 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { | |
388 | if (mnt->mnt_flags & fs_infop->flag) | |
389 | seq_puts(m, fs_infop->str); | |
390 | } | |
391 | if (mnt->mnt_sb->s_op->show_options) | |
392 | err = mnt->mnt_sb->s_op->show_options(m, mnt); | |
393 | seq_puts(m, " 0 0\n"); | |
394 | return err; | |
395 | } | |
396 | ||
397 | struct seq_operations mounts_op = { | |
398 | .start = m_start, | |
399 | .next = m_next, | |
400 | .stop = m_stop, | |
401 | .show = show_vfsmnt | |
402 | }; | |
403 | ||
b4629fe2 CL |
404 | static int show_vfsstat(struct seq_file *m, void *v) |
405 | { | |
b0765fb8 | 406 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
b4629fe2 CL |
407 | int err = 0; |
408 | ||
409 | /* device */ | |
410 | if (mnt->mnt_devname) { | |
411 | seq_puts(m, "device "); | |
412 | mangle(m, mnt->mnt_devname); | |
413 | } else | |
414 | seq_puts(m, "no device"); | |
415 | ||
416 | /* mount point */ | |
417 | seq_puts(m, " mounted on "); | |
418 | seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); | |
419 | seq_putc(m, ' '); | |
420 | ||
421 | /* file system type */ | |
422 | seq_puts(m, "with fstype "); | |
423 | mangle(m, mnt->mnt_sb->s_type->name); | |
424 | ||
425 | /* optional statistics */ | |
426 | if (mnt->mnt_sb->s_op->show_stats) { | |
427 | seq_putc(m, ' '); | |
428 | err = mnt->mnt_sb->s_op->show_stats(m, mnt); | |
429 | } | |
430 | ||
431 | seq_putc(m, '\n'); | |
432 | return err; | |
433 | } | |
434 | ||
435 | struct seq_operations mountstats_op = { | |
436 | .start = m_start, | |
437 | .next = m_next, | |
438 | .stop = m_stop, | |
439 | .show = show_vfsstat, | |
440 | }; | |
441 | ||
1da177e4 LT |
442 | /** |
443 | * may_umount_tree - check if a mount tree is busy | |
444 | * @mnt: root of mount tree | |
445 | * | |
446 | * This is called to check if a tree of mounts has any | |
447 | * open files, pwds, chroots or sub mounts that are | |
448 | * busy. | |
449 | */ | |
450 | int may_umount_tree(struct vfsmount *mnt) | |
451 | { | |
36341f64 RP |
452 | int actual_refs = 0; |
453 | int minimum_refs = 0; | |
454 | struct vfsmount *p; | |
1da177e4 LT |
455 | |
456 | spin_lock(&vfsmount_lock); | |
36341f64 | 457 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
1da177e4 LT |
458 | actual_refs += atomic_read(&p->mnt_count); |
459 | minimum_refs += 2; | |
1da177e4 LT |
460 | } |
461 | spin_unlock(&vfsmount_lock); | |
462 | ||
463 | if (actual_refs > minimum_refs) | |
e3474a8e | 464 | return 0; |
1da177e4 | 465 | |
e3474a8e | 466 | return 1; |
1da177e4 LT |
467 | } |
468 | ||
469 | EXPORT_SYMBOL(may_umount_tree); | |
470 | ||
471 | /** | |
472 | * may_umount - check if a mount point is busy | |
473 | * @mnt: root of mount | |
474 | * | |
475 | * This is called to check if a mount point has any | |
476 | * open files, pwds, chroots or sub mounts. If the | |
477 | * mount has sub mounts this will return busy | |
478 | * regardless of whether the sub mounts are busy. | |
479 | * | |
480 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
481 | * give false negatives. The main reason why it's here is that we need | |
482 | * a non-destructive way to look for easily umountable filesystems. | |
483 | */ | |
484 | int may_umount(struct vfsmount *mnt) | |
485 | { | |
e3474a8e | 486 | int ret = 1; |
a05964f3 RP |
487 | spin_lock(&vfsmount_lock); |
488 | if (propagate_mount_busy(mnt, 2)) | |
e3474a8e | 489 | ret = 0; |
a05964f3 RP |
490 | spin_unlock(&vfsmount_lock); |
491 | return ret; | |
1da177e4 LT |
492 | } |
493 | ||
494 | EXPORT_SYMBOL(may_umount); | |
495 | ||
b90fa9ae | 496 | void release_mounts(struct list_head *head) |
70fbcdf4 RP |
497 | { |
498 | struct vfsmount *mnt; | |
bf066c7d | 499 | while (!list_empty(head)) { |
b5e61818 | 500 | mnt = list_first_entry(head, struct vfsmount, mnt_hash); |
70fbcdf4 RP |
501 | list_del_init(&mnt->mnt_hash); |
502 | if (mnt->mnt_parent != mnt) { | |
503 | struct dentry *dentry; | |
504 | struct vfsmount *m; | |
505 | spin_lock(&vfsmount_lock); | |
506 | dentry = mnt->mnt_mountpoint; | |
507 | m = mnt->mnt_parent; | |
508 | mnt->mnt_mountpoint = mnt->mnt_root; | |
509 | mnt->mnt_parent = mnt; | |
510 | spin_unlock(&vfsmount_lock); | |
511 | dput(dentry); | |
512 | mntput(m); | |
513 | } | |
514 | mntput(mnt); | |
515 | } | |
516 | } | |
517 | ||
a05964f3 | 518 | void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) |
1da177e4 LT |
519 | { |
520 | struct vfsmount *p; | |
1da177e4 | 521 | |
1bfba4e8 AM |
522 | for (p = mnt; p; p = next_mnt(p, mnt)) |
523 | list_move(&p->mnt_hash, kill); | |
1da177e4 | 524 | |
a05964f3 RP |
525 | if (propagate) |
526 | propagate_umount(kill); | |
527 | ||
70fbcdf4 RP |
528 | list_for_each_entry(p, kill, mnt_hash) { |
529 | list_del_init(&p->mnt_expire); | |
530 | list_del_init(&p->mnt_list); | |
6b3286ed KK |
531 | __touch_mnt_namespace(p->mnt_ns); |
532 | p->mnt_ns = NULL; | |
70fbcdf4 RP |
533 | list_del_init(&p->mnt_child); |
534 | if (p->mnt_parent != p) | |
f30ac319 | 535 | p->mnt_mountpoint->d_mounted--; |
a05964f3 | 536 | change_mnt_propagation(p, MS_PRIVATE); |
1da177e4 LT |
537 | } |
538 | } | |
539 | ||
540 | static int do_umount(struct vfsmount *mnt, int flags) | |
541 | { | |
b58fed8b | 542 | struct super_block *sb = mnt->mnt_sb; |
1da177e4 | 543 | int retval; |
70fbcdf4 | 544 | LIST_HEAD(umount_list); |
1da177e4 LT |
545 | |
546 | retval = security_sb_umount(mnt, flags); | |
547 | if (retval) | |
548 | return retval; | |
549 | ||
550 | /* | |
551 | * Allow userspace to request a mountpoint be expired rather than | |
552 | * unmounting unconditionally. Unmount only happens if: | |
553 | * (1) the mark is already set (the mark is cleared by mntput()) | |
554 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
555 | */ | |
556 | if (flags & MNT_EXPIRE) { | |
557 | if (mnt == current->fs->rootmnt || | |
558 | flags & (MNT_FORCE | MNT_DETACH)) | |
559 | return -EINVAL; | |
560 | ||
561 | if (atomic_read(&mnt->mnt_count) != 2) | |
562 | return -EBUSY; | |
563 | ||
564 | if (!xchg(&mnt->mnt_expiry_mark, 1)) | |
565 | return -EAGAIN; | |
566 | } | |
567 | ||
568 | /* | |
569 | * If we may have to abort operations to get out of this | |
570 | * mount, and they will themselves hold resources we must | |
571 | * allow the fs to do things. In the Unix tradition of | |
572 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
573 | * might fail to complete on the first run through as other tasks | |
574 | * must return, and the like. Thats for the mount program to worry | |
575 | * about for the moment. | |
576 | */ | |
577 | ||
578 | lock_kernel(); | |
8b512d9a TM |
579 | if (sb->s_op->umount_begin) |
580 | sb->s_op->umount_begin(mnt, flags); | |
1da177e4 LT |
581 | unlock_kernel(); |
582 | ||
583 | /* | |
584 | * No sense to grab the lock for this test, but test itself looks | |
585 | * somewhat bogus. Suggestions for better replacement? | |
586 | * Ho-hum... In principle, we might treat that as umount + switch | |
587 | * to rootfs. GC would eventually take care of the old vfsmount. | |
588 | * Actually it makes sense, especially if rootfs would contain a | |
589 | * /reboot - static binary that would close all descriptors and | |
590 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
591 | */ | |
592 | if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) { | |
593 | /* | |
594 | * Special case for "unmounting" root ... | |
595 | * we just try to remount it readonly. | |
596 | */ | |
597 | down_write(&sb->s_umount); | |
598 | if (!(sb->s_flags & MS_RDONLY)) { | |
599 | lock_kernel(); | |
600 | DQUOT_OFF(sb); | |
601 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); | |
602 | unlock_kernel(); | |
603 | } | |
604 | up_write(&sb->s_umount); | |
605 | return retval; | |
606 | } | |
607 | ||
390c6843 | 608 | down_write(&namespace_sem); |
1da177e4 | 609 | spin_lock(&vfsmount_lock); |
5addc5dd | 610 | event++; |
1da177e4 | 611 | |
1da177e4 | 612 | retval = -EBUSY; |
a05964f3 | 613 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
1da177e4 | 614 | if (!list_empty(&mnt->mnt_list)) |
a05964f3 | 615 | umount_tree(mnt, 1, &umount_list); |
1da177e4 LT |
616 | retval = 0; |
617 | } | |
618 | spin_unlock(&vfsmount_lock); | |
619 | if (retval) | |
620 | security_sb_umount_busy(mnt); | |
390c6843 | 621 | up_write(&namespace_sem); |
70fbcdf4 | 622 | release_mounts(&umount_list); |
1da177e4 LT |
623 | return retval; |
624 | } | |
625 | ||
626 | /* | |
627 | * Now umount can handle mount points as well as block devices. | |
628 | * This is important for filesystems which use unnamed block devices. | |
629 | * | |
630 | * We now support a flag for forced unmount like the other 'big iron' | |
631 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD | |
632 | */ | |
633 | ||
634 | asmlinkage long sys_umount(char __user * name, int flags) | |
635 | { | |
636 | struct nameidata nd; | |
637 | int retval; | |
638 | ||
639 | retval = __user_walk(name, LOOKUP_FOLLOW, &nd); | |
640 | if (retval) | |
641 | goto out; | |
642 | retval = -EINVAL; | |
643 | if (nd.dentry != nd.mnt->mnt_root) | |
644 | goto dput_and_out; | |
645 | if (!check_mnt(nd.mnt)) | |
646 | goto dput_and_out; | |
647 | ||
648 | retval = -EPERM; | |
649 | if (!capable(CAP_SYS_ADMIN)) | |
650 | goto dput_and_out; | |
651 | ||
652 | retval = do_umount(nd.mnt, flags); | |
653 | dput_and_out: | |
654 | path_release_on_umount(&nd); | |
655 | out: | |
656 | return retval; | |
657 | } | |
658 | ||
659 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT | |
660 | ||
661 | /* | |
b58fed8b | 662 | * The 2.0 compatible umount. No flags. |
1da177e4 | 663 | */ |
1da177e4 LT |
664 | asmlinkage long sys_oldumount(char __user * name) |
665 | { | |
b58fed8b | 666 | return sys_umount(name, 0); |
1da177e4 LT |
667 | } |
668 | ||
669 | #endif | |
670 | ||
671 | static int mount_is_safe(struct nameidata *nd) | |
672 | { | |
673 | if (capable(CAP_SYS_ADMIN)) | |
674 | return 0; | |
675 | return -EPERM; | |
676 | #ifdef notyet | |
677 | if (S_ISLNK(nd->dentry->d_inode->i_mode)) | |
678 | return -EPERM; | |
679 | if (nd->dentry->d_inode->i_mode & S_ISVTX) { | |
680 | if (current->uid != nd->dentry->d_inode->i_uid) | |
681 | return -EPERM; | |
682 | } | |
e4543edd | 683 | if (vfs_permission(nd, MAY_WRITE)) |
1da177e4 LT |
684 | return -EPERM; |
685 | return 0; | |
686 | #endif | |
687 | } | |
688 | ||
b58fed8b | 689 | static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry) |
1da177e4 LT |
690 | { |
691 | while (1) { | |
692 | if (d == dentry) | |
693 | return 1; | |
694 | if (d == NULL || d == d->d_parent) | |
695 | return 0; | |
696 | d = d->d_parent; | |
697 | } | |
698 | } | |
699 | ||
b90fa9ae | 700 | struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, |
36341f64 | 701 | int flag) |
1da177e4 LT |
702 | { |
703 | struct vfsmount *res, *p, *q, *r, *s; | |
1da177e4 LT |
704 | struct nameidata nd; |
705 | ||
9676f0c6 RP |
706 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) |
707 | return NULL; | |
708 | ||
36341f64 | 709 | res = q = clone_mnt(mnt, dentry, flag); |
1da177e4 LT |
710 | if (!q) |
711 | goto Enomem; | |
712 | q->mnt_mountpoint = mnt->mnt_mountpoint; | |
713 | ||
714 | p = mnt; | |
fdadd65f | 715 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
1da177e4 LT |
716 | if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry)) |
717 | continue; | |
718 | ||
719 | for (s = r; s; s = next_mnt(s, r)) { | |
9676f0c6 RP |
720 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { |
721 | s = skip_mnt_tree(s); | |
722 | continue; | |
723 | } | |
1da177e4 LT |
724 | while (p != s->mnt_parent) { |
725 | p = p->mnt_parent; | |
726 | q = q->mnt_parent; | |
727 | } | |
728 | p = s; | |
729 | nd.mnt = q; | |
730 | nd.dentry = p->mnt_mountpoint; | |
36341f64 | 731 | q = clone_mnt(p, p->mnt_root, flag); |
1da177e4 LT |
732 | if (!q) |
733 | goto Enomem; | |
734 | spin_lock(&vfsmount_lock); | |
735 | list_add_tail(&q->mnt_list, &res->mnt_list); | |
736 | attach_mnt(q, &nd); | |
737 | spin_unlock(&vfsmount_lock); | |
738 | } | |
739 | } | |
740 | return res; | |
b58fed8b | 741 | Enomem: |
1da177e4 | 742 | if (res) { |
70fbcdf4 | 743 | LIST_HEAD(umount_list); |
1da177e4 | 744 | spin_lock(&vfsmount_lock); |
a05964f3 | 745 | umount_tree(res, 0, &umount_list); |
1da177e4 | 746 | spin_unlock(&vfsmount_lock); |
70fbcdf4 | 747 | release_mounts(&umount_list); |
1da177e4 LT |
748 | } |
749 | return NULL; | |
750 | } | |
751 | ||
8aec0809 AV |
752 | struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry) |
753 | { | |
754 | struct vfsmount *tree; | |
755 | down_read(&namespace_sem); | |
756 | tree = copy_tree(mnt, dentry, CL_COPY_ALL | CL_PRIVATE); | |
757 | up_read(&namespace_sem); | |
758 | return tree; | |
759 | } | |
760 | ||
761 | void drop_collected_mounts(struct vfsmount *mnt) | |
762 | { | |
763 | LIST_HEAD(umount_list); | |
764 | down_read(&namespace_sem); | |
765 | spin_lock(&vfsmount_lock); | |
766 | umount_tree(mnt, 0, &umount_list); | |
767 | spin_unlock(&vfsmount_lock); | |
768 | up_read(&namespace_sem); | |
769 | release_mounts(&umount_list); | |
770 | } | |
771 | ||
b90fa9ae RP |
772 | /* |
773 | * @source_mnt : mount tree to be attached | |
21444403 RP |
774 | * @nd : place the mount tree @source_mnt is attached |
775 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
776 | * store the parent mount and mountpoint dentry. | |
777 | * (done when source_mnt is moved) | |
b90fa9ae RP |
778 | * |
779 | * NOTE: in the table below explains the semantics when a source mount | |
780 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
781 | * --------------------------------------------------------------------------- |
782 | * | BIND MOUNT OPERATION | | |
783 | * |************************************************************************** | |
784 | * | source-->| shared | private | slave | unbindable | | |
785 | * | dest | | | | | | |
786 | * | | | | | | | | |
787 | * | v | | | | | | |
788 | * |************************************************************************** | |
789 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
790 | * | | | | | | | |
791 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
792 | * *************************************************************************** | |
b90fa9ae RP |
793 | * A bind operation clones the source mount and mounts the clone on the |
794 | * destination mount. | |
795 | * | |
796 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
797 | * tree of the destination mount and the cloned mount is added to | |
798 | * the peer group of the source mount. | |
799 | * (+) the cloned mount is created under the destination mount and is marked | |
800 | * as shared. The cloned mount is added to the peer group of the source | |
801 | * mount. | |
5afe0022 RP |
802 | * (+++) the mount is propagated to all the mounts in the propagation tree |
803 | * of the destination mount and the cloned mount is made slave | |
804 | * of the same master as that of the source mount. The cloned mount | |
805 | * is marked as 'shared and slave'. | |
806 | * (*) the cloned mount is made a slave of the same master as that of the | |
807 | * source mount. | |
808 | * | |
9676f0c6 RP |
809 | * --------------------------------------------------------------------------- |
810 | * | MOVE MOUNT OPERATION | | |
811 | * |************************************************************************** | |
812 | * | source-->| shared | private | slave | unbindable | | |
813 | * | dest | | | | | | |
814 | * | | | | | | | | |
815 | * | v | | | | | | |
816 | * |************************************************************************** | |
817 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
818 | * | | | | | | | |
819 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
820 | * *************************************************************************** | |
5afe0022 RP |
821 | * |
822 | * (+) the mount is moved to the destination. And is then propagated to | |
823 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 824 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
825 | * (+++) the mount is moved to the destination and is then propagated to |
826 | * all the mounts belonging to the destination mount's propagation tree. | |
827 | * the mount is marked as 'shared and slave'. | |
828 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
829 | * |
830 | * if the source mount is a tree, the operations explained above is | |
831 | * applied to each mount in the tree. | |
832 | * Must be called without spinlocks held, since this function can sleep | |
833 | * in allocations. | |
834 | */ | |
835 | static int attach_recursive_mnt(struct vfsmount *source_mnt, | |
21444403 | 836 | struct nameidata *nd, struct nameidata *parent_nd) |
b90fa9ae RP |
837 | { |
838 | LIST_HEAD(tree_list); | |
839 | struct vfsmount *dest_mnt = nd->mnt; | |
840 | struct dentry *dest_dentry = nd->dentry; | |
841 | struct vfsmount *child, *p; | |
842 | ||
843 | if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) | |
844 | return -EINVAL; | |
845 | ||
846 | if (IS_MNT_SHARED(dest_mnt)) { | |
847 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) | |
848 | set_mnt_shared(p); | |
849 | } | |
850 | ||
851 | spin_lock(&vfsmount_lock); | |
21444403 RP |
852 | if (parent_nd) { |
853 | detach_mnt(source_mnt, parent_nd); | |
854 | attach_mnt(source_mnt, nd); | |
6b3286ed | 855 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
21444403 RP |
856 | } else { |
857 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); | |
858 | commit_tree(source_mnt); | |
859 | } | |
b90fa9ae RP |
860 | |
861 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { | |
862 | list_del_init(&child->mnt_hash); | |
863 | commit_tree(child); | |
864 | } | |
865 | spin_unlock(&vfsmount_lock); | |
866 | return 0; | |
867 | } | |
868 | ||
1da177e4 LT |
869 | static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) |
870 | { | |
871 | int err; | |
872 | if (mnt->mnt_sb->s_flags & MS_NOUSER) | |
873 | return -EINVAL; | |
874 | ||
875 | if (S_ISDIR(nd->dentry->d_inode->i_mode) != | |
876 | S_ISDIR(mnt->mnt_root->d_inode->i_mode)) | |
877 | return -ENOTDIR; | |
878 | ||
879 | err = -ENOENT; | |
1b1dcc1b | 880 | mutex_lock(&nd->dentry->d_inode->i_mutex); |
1da177e4 LT |
881 | if (IS_DEADDIR(nd->dentry->d_inode)) |
882 | goto out_unlock; | |
883 | ||
884 | err = security_sb_check_sb(mnt, nd); | |
885 | if (err) | |
886 | goto out_unlock; | |
887 | ||
888 | err = -ENOENT; | |
b90fa9ae | 889 | if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) |
21444403 | 890 | err = attach_recursive_mnt(mnt, nd, NULL); |
1da177e4 | 891 | out_unlock: |
1b1dcc1b | 892 | mutex_unlock(&nd->dentry->d_inode->i_mutex); |
1da177e4 LT |
893 | if (!err) |
894 | security_sb_post_addmount(mnt, nd); | |
895 | return err; | |
896 | } | |
897 | ||
07b20889 RP |
898 | /* |
899 | * recursively change the type of the mountpoint. | |
900 | */ | |
901 | static int do_change_type(struct nameidata *nd, int flag) | |
902 | { | |
903 | struct vfsmount *m, *mnt = nd->mnt; | |
904 | int recurse = flag & MS_REC; | |
905 | int type = flag & ~MS_REC; | |
906 | ||
ee6f9582 MS |
907 | if (!capable(CAP_SYS_ADMIN)) |
908 | return -EPERM; | |
909 | ||
07b20889 RP |
910 | if (nd->dentry != nd->mnt->mnt_root) |
911 | return -EINVAL; | |
912 | ||
913 | down_write(&namespace_sem); | |
914 | spin_lock(&vfsmount_lock); | |
915 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) | |
916 | change_mnt_propagation(m, type); | |
917 | spin_unlock(&vfsmount_lock); | |
918 | up_write(&namespace_sem); | |
919 | return 0; | |
920 | } | |
921 | ||
1da177e4 LT |
922 | /* |
923 | * do loopback mount. | |
924 | */ | |
eee391a6 | 925 | static int do_loopback(struct nameidata *nd, char *old_name, int recurse) |
1da177e4 LT |
926 | { |
927 | struct nameidata old_nd; | |
928 | struct vfsmount *mnt = NULL; | |
929 | int err = mount_is_safe(nd); | |
930 | if (err) | |
931 | return err; | |
932 | if (!old_name || !*old_name) | |
933 | return -EINVAL; | |
934 | err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); | |
935 | if (err) | |
936 | return err; | |
937 | ||
390c6843 | 938 | down_write(&namespace_sem); |
1da177e4 | 939 | err = -EINVAL; |
9676f0c6 RP |
940 | if (IS_MNT_UNBINDABLE(old_nd.mnt)) |
941 | goto out; | |
942 | ||
ccd48bc7 AV |
943 | if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) |
944 | goto out; | |
1da177e4 | 945 | |
ccd48bc7 AV |
946 | err = -ENOMEM; |
947 | if (recurse) | |
36341f64 | 948 | mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0); |
ccd48bc7 | 949 | else |
36341f64 | 950 | mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0); |
ccd48bc7 AV |
951 | |
952 | if (!mnt) | |
953 | goto out; | |
954 | ||
ccd48bc7 AV |
955 | err = graft_tree(mnt, nd); |
956 | if (err) { | |
70fbcdf4 | 957 | LIST_HEAD(umount_list); |
1da177e4 | 958 | spin_lock(&vfsmount_lock); |
a05964f3 | 959 | umount_tree(mnt, 0, &umount_list); |
1da177e4 | 960 | spin_unlock(&vfsmount_lock); |
70fbcdf4 | 961 | release_mounts(&umount_list); |
5b83d2c5 | 962 | } |
1da177e4 | 963 | |
ccd48bc7 | 964 | out: |
390c6843 | 965 | up_write(&namespace_sem); |
1da177e4 LT |
966 | path_release(&old_nd); |
967 | return err; | |
968 | } | |
969 | ||
970 | /* | |
971 | * change filesystem flags. dir should be a physical root of filesystem. | |
972 | * If you've mounted a non-root directory somewhere and want to do remount | |
973 | * on it - tough luck. | |
974 | */ | |
1da177e4 LT |
975 | static int do_remount(struct nameidata *nd, int flags, int mnt_flags, |
976 | void *data) | |
977 | { | |
978 | int err; | |
b58fed8b | 979 | struct super_block *sb = nd->mnt->mnt_sb; |
1da177e4 LT |
980 | |
981 | if (!capable(CAP_SYS_ADMIN)) | |
982 | return -EPERM; | |
983 | ||
984 | if (!check_mnt(nd->mnt)) | |
985 | return -EINVAL; | |
986 | ||
987 | if (nd->dentry != nd->mnt->mnt_root) | |
988 | return -EINVAL; | |
989 | ||
990 | down_write(&sb->s_umount); | |
991 | err = do_remount_sb(sb, flags, data, 0); | |
992 | if (!err) | |
b58fed8b | 993 | nd->mnt->mnt_flags = mnt_flags; |
1da177e4 LT |
994 | up_write(&sb->s_umount); |
995 | if (!err) | |
996 | security_sb_post_remount(nd->mnt, flags, data); | |
997 | return err; | |
998 | } | |
999 | ||
9676f0c6 RP |
1000 | static inline int tree_contains_unbindable(struct vfsmount *mnt) |
1001 | { | |
1002 | struct vfsmount *p; | |
1003 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
1004 | if (IS_MNT_UNBINDABLE(p)) | |
1005 | return 1; | |
1006 | } | |
1007 | return 0; | |
1008 | } | |
1009 | ||
1da177e4 LT |
1010 | static int do_move_mount(struct nameidata *nd, char *old_name) |
1011 | { | |
1012 | struct nameidata old_nd, parent_nd; | |
1013 | struct vfsmount *p; | |
1014 | int err = 0; | |
1015 | if (!capable(CAP_SYS_ADMIN)) | |
1016 | return -EPERM; | |
1017 | if (!old_name || !*old_name) | |
1018 | return -EINVAL; | |
1019 | err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); | |
1020 | if (err) | |
1021 | return err; | |
1022 | ||
390c6843 | 1023 | down_write(&namespace_sem); |
b58fed8b | 1024 | while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
1da177e4 LT |
1025 | ; |
1026 | err = -EINVAL; | |
1027 | if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) | |
1028 | goto out; | |
1029 | ||
1030 | err = -ENOENT; | |
1b1dcc1b | 1031 | mutex_lock(&nd->dentry->d_inode->i_mutex); |
1da177e4 LT |
1032 | if (IS_DEADDIR(nd->dentry->d_inode)) |
1033 | goto out1; | |
1034 | ||
1da177e4 | 1035 | if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) |
21444403 | 1036 | goto out1; |
1da177e4 LT |
1037 | |
1038 | err = -EINVAL; | |
1039 | if (old_nd.dentry != old_nd.mnt->mnt_root) | |
21444403 | 1040 | goto out1; |
1da177e4 LT |
1041 | |
1042 | if (old_nd.mnt == old_nd.mnt->mnt_parent) | |
21444403 | 1043 | goto out1; |
1da177e4 LT |
1044 | |
1045 | if (S_ISDIR(nd->dentry->d_inode->i_mode) != | |
1046 | S_ISDIR(old_nd.dentry->d_inode->i_mode)) | |
21444403 RP |
1047 | goto out1; |
1048 | /* | |
1049 | * Don't move a mount residing in a shared parent. | |
1050 | */ | |
1051 | if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent)) | |
1052 | goto out1; | |
9676f0c6 RP |
1053 | /* |
1054 | * Don't move a mount tree containing unbindable mounts to a destination | |
1055 | * mount which is shared. | |
1056 | */ | |
1057 | if (IS_MNT_SHARED(nd->mnt) && tree_contains_unbindable(old_nd.mnt)) | |
1058 | goto out1; | |
1da177e4 | 1059 | err = -ELOOP; |
b58fed8b | 1060 | for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent) |
1da177e4 | 1061 | if (p == old_nd.mnt) |
21444403 | 1062 | goto out1; |
1da177e4 | 1063 | |
21444403 RP |
1064 | if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd))) |
1065 | goto out1; | |
1da177e4 | 1066 | |
21444403 | 1067 | spin_lock(&vfsmount_lock); |
1da177e4 LT |
1068 | /* if the mount is moved, it should no longer be expire |
1069 | * automatically */ | |
55e700b9 | 1070 | list_del_init(&old_nd.mnt->mnt_expire); |
1da177e4 LT |
1071 | spin_unlock(&vfsmount_lock); |
1072 | out1: | |
1b1dcc1b | 1073 | mutex_unlock(&nd->dentry->d_inode->i_mutex); |
1da177e4 | 1074 | out: |
390c6843 | 1075 | up_write(&namespace_sem); |
1da177e4 LT |
1076 | if (!err) |
1077 | path_release(&parent_nd); | |
1078 | path_release(&old_nd); | |
1079 | return err; | |
1080 | } | |
1081 | ||
1082 | /* | |
1083 | * create a new mount for userspace and request it to be added into the | |
1084 | * namespace's tree | |
1085 | */ | |
1086 | static int do_new_mount(struct nameidata *nd, char *type, int flags, | |
1087 | int mnt_flags, char *name, void *data) | |
1088 | { | |
1089 | struct vfsmount *mnt; | |
1090 | ||
1091 | if (!type || !memchr(type, 0, PAGE_SIZE)) | |
1092 | return -EINVAL; | |
1093 | ||
1094 | /* we need capabilities... */ | |
1095 | if (!capable(CAP_SYS_ADMIN)) | |
1096 | return -EPERM; | |
1097 | ||
1098 | mnt = do_kern_mount(type, flags, name, data); | |
1099 | if (IS_ERR(mnt)) | |
1100 | return PTR_ERR(mnt); | |
1101 | ||
1102 | return do_add_mount(mnt, nd, mnt_flags, NULL); | |
1103 | } | |
1104 | ||
1105 | /* | |
1106 | * add a mount into a namespace's mount tree | |
1107 | * - provide the option of adding the new mount to an expiration list | |
1108 | */ | |
1109 | int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, | |
1110 | int mnt_flags, struct list_head *fslist) | |
1111 | { | |
1112 | int err; | |
1113 | ||
390c6843 | 1114 | down_write(&namespace_sem); |
1da177e4 | 1115 | /* Something was mounted here while we slept */ |
b58fed8b | 1116 | while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
1da177e4 LT |
1117 | ; |
1118 | err = -EINVAL; | |
1119 | if (!check_mnt(nd->mnt)) | |
1120 | goto unlock; | |
1121 | ||
1122 | /* Refuse the same filesystem on the same mount point */ | |
1123 | err = -EBUSY; | |
1124 | if (nd->mnt->mnt_sb == newmnt->mnt_sb && | |
1125 | nd->mnt->mnt_root == nd->dentry) | |
1126 | goto unlock; | |
1127 | ||
1128 | err = -EINVAL; | |
1129 | if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) | |
1130 | goto unlock; | |
1131 | ||
1132 | newmnt->mnt_flags = mnt_flags; | |
5b83d2c5 RP |
1133 | if ((err = graft_tree(newmnt, nd))) |
1134 | goto unlock; | |
1da177e4 | 1135 | |
5b83d2c5 | 1136 | if (fslist) { |
1da177e4 LT |
1137 | /* add to the specified expiration list */ |
1138 | spin_lock(&vfsmount_lock); | |
55e700b9 | 1139 | list_add_tail(&newmnt->mnt_expire, fslist); |
1da177e4 LT |
1140 | spin_unlock(&vfsmount_lock); |
1141 | } | |
390c6843 | 1142 | up_write(&namespace_sem); |
5b83d2c5 | 1143 | return 0; |
1da177e4 LT |
1144 | |
1145 | unlock: | |
390c6843 | 1146 | up_write(&namespace_sem); |
1da177e4 LT |
1147 | mntput(newmnt); |
1148 | return err; | |
1149 | } | |
1150 | ||
1151 | EXPORT_SYMBOL_GPL(do_add_mount); | |
1152 | ||
70fbcdf4 RP |
1153 | static void expire_mount(struct vfsmount *mnt, struct list_head *mounts, |
1154 | struct list_head *umounts) | |
24ca2af1 MS |
1155 | { |
1156 | spin_lock(&vfsmount_lock); | |
1157 | ||
ed42c879 MS |
1158 | /* |
1159 | * Check if mount is still attached, if not, let whoever holds it deal | |
1160 | * with the sucker | |
1161 | */ | |
1162 | if (mnt->mnt_parent == mnt) { | |
1163 | spin_unlock(&vfsmount_lock); | |
1164 | return; | |
1165 | } | |
1166 | ||
24ca2af1 MS |
1167 | /* |
1168 | * Check that it is still dead: the count should now be 2 - as | |
1169 | * contributed by the vfsmount parent and the mntget above | |
1170 | */ | |
a05964f3 | 1171 | if (!propagate_mount_busy(mnt, 2)) { |
24ca2af1 | 1172 | /* delete from the namespace */ |
6b3286ed | 1173 | touch_mnt_namespace(mnt->mnt_ns); |
24ca2af1 | 1174 | list_del_init(&mnt->mnt_list); |
6b3286ed | 1175 | mnt->mnt_ns = NULL; |
a05964f3 | 1176 | umount_tree(mnt, 1, umounts); |
24ca2af1 | 1177 | spin_unlock(&vfsmount_lock); |
24ca2af1 MS |
1178 | } else { |
1179 | /* | |
1180 | * Someone brought it back to life whilst we didn't have any | |
1181 | * locks held so return it to the expiration list | |
1182 | */ | |
55e700b9 | 1183 | list_add_tail(&mnt->mnt_expire, mounts); |
24ca2af1 MS |
1184 | spin_unlock(&vfsmount_lock); |
1185 | } | |
1186 | } | |
1187 | ||
5528f911 TM |
1188 | /* |
1189 | * go through the vfsmounts we've just consigned to the graveyard to | |
1190 | * - check that they're still dead | |
1191 | * - delete the vfsmount from the appropriate namespace under lock | |
1192 | * - dispose of the corpse | |
1193 | */ | |
1194 | static void expire_mount_list(struct list_head *graveyard, struct list_head *mounts) | |
1195 | { | |
6b3286ed | 1196 | struct mnt_namespace *ns; |
5528f911 TM |
1197 | struct vfsmount *mnt; |
1198 | ||
1199 | while (!list_empty(graveyard)) { | |
1200 | LIST_HEAD(umounts); | |
b5e61818 | 1201 | mnt = list_first_entry(graveyard, struct vfsmount, mnt_expire); |
5528f911 TM |
1202 | list_del_init(&mnt->mnt_expire); |
1203 | ||
1204 | /* don't do anything if the namespace is dead - all the | |
1205 | * vfsmounts from it are going away anyway */ | |
6b3286ed KK |
1206 | ns = mnt->mnt_ns; |
1207 | if (!ns || !ns->root) | |
5528f911 | 1208 | continue; |
6b3286ed | 1209 | get_mnt_ns(ns); |
5528f911 TM |
1210 | |
1211 | spin_unlock(&vfsmount_lock); | |
1212 | down_write(&namespace_sem); | |
1213 | expire_mount(mnt, mounts, &umounts); | |
1214 | up_write(&namespace_sem); | |
1215 | release_mounts(&umounts); | |
1216 | mntput(mnt); | |
6b3286ed | 1217 | put_mnt_ns(ns); |
5528f911 TM |
1218 | spin_lock(&vfsmount_lock); |
1219 | } | |
1220 | } | |
1221 | ||
1da177e4 LT |
1222 | /* |
1223 | * process a list of expirable mountpoints with the intent of discarding any | |
1224 | * mountpoints that aren't in use and haven't been touched since last we came | |
1225 | * here | |
1226 | */ | |
1227 | void mark_mounts_for_expiry(struct list_head *mounts) | |
1228 | { | |
1da177e4 LT |
1229 | struct vfsmount *mnt, *next; |
1230 | LIST_HEAD(graveyard); | |
1231 | ||
1232 | if (list_empty(mounts)) | |
1233 | return; | |
1234 | ||
1235 | spin_lock(&vfsmount_lock); | |
1236 | ||
1237 | /* extract from the expiration list every vfsmount that matches the | |
1238 | * following criteria: | |
1239 | * - only referenced by its parent vfsmount | |
1240 | * - still marked for expiry (marked on the last call here; marks are | |
1241 | * cleared by mntput()) | |
1242 | */ | |
55e700b9 | 1243 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
1da177e4 LT |
1244 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
1245 | atomic_read(&mnt->mnt_count) != 1) | |
1246 | continue; | |
1247 | ||
1248 | mntget(mnt); | |
55e700b9 | 1249 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 LT |
1250 | } |
1251 | ||
5528f911 | 1252 | expire_mount_list(&graveyard, mounts); |
1da177e4 | 1253 | |
5528f911 TM |
1254 | spin_unlock(&vfsmount_lock); |
1255 | } | |
1256 | ||
1257 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
1258 | ||
1259 | /* | |
1260 | * Ripoff of 'select_parent()' | |
1261 | * | |
1262 | * search the list of submounts for a given mountpoint, and move any | |
1263 | * shrinkable submounts to the 'graveyard' list. | |
1264 | */ | |
1265 | static int select_submounts(struct vfsmount *parent, struct list_head *graveyard) | |
1266 | { | |
1267 | struct vfsmount *this_parent = parent; | |
1268 | struct list_head *next; | |
1269 | int found = 0; | |
1270 | ||
1271 | repeat: | |
1272 | next = this_parent->mnt_mounts.next; | |
1273 | resume: | |
1274 | while (next != &this_parent->mnt_mounts) { | |
1275 | struct list_head *tmp = next; | |
1276 | struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child); | |
1277 | ||
1278 | next = tmp->next; | |
1279 | if (!(mnt->mnt_flags & MNT_SHRINKABLE)) | |
1da177e4 | 1280 | continue; |
5528f911 TM |
1281 | /* |
1282 | * Descend a level if the d_mounts list is non-empty. | |
1283 | */ | |
1284 | if (!list_empty(&mnt->mnt_mounts)) { | |
1285 | this_parent = mnt; | |
1286 | goto repeat; | |
1287 | } | |
1da177e4 | 1288 | |
5528f911 TM |
1289 | if (!propagate_mount_busy(mnt, 1)) { |
1290 | mntget(mnt); | |
1291 | list_move_tail(&mnt->mnt_expire, graveyard); | |
1292 | found++; | |
1293 | } | |
1da177e4 | 1294 | } |
5528f911 TM |
1295 | /* |
1296 | * All done at this level ... ascend and resume the search | |
1297 | */ | |
1298 | if (this_parent != parent) { | |
1299 | next = this_parent->mnt_child.next; | |
1300 | this_parent = this_parent->mnt_parent; | |
1301 | goto resume; | |
1302 | } | |
1303 | return found; | |
1304 | } | |
1305 | ||
1306 | /* | |
1307 | * process a list of expirable mountpoints with the intent of discarding any | |
1308 | * submounts of a specific parent mountpoint | |
1309 | */ | |
1310 | void shrink_submounts(struct vfsmount *mountpoint, struct list_head *mounts) | |
1311 | { | |
1312 | LIST_HEAD(graveyard); | |
1313 | int found; | |
1314 | ||
1315 | spin_lock(&vfsmount_lock); | |
1316 | ||
1317 | /* extract submounts of 'mountpoint' from the expiration list */ | |
1318 | while ((found = select_submounts(mountpoint, &graveyard)) != 0) | |
1319 | expire_mount_list(&graveyard, mounts); | |
1da177e4 LT |
1320 | |
1321 | spin_unlock(&vfsmount_lock); | |
1322 | } | |
1323 | ||
5528f911 | 1324 | EXPORT_SYMBOL_GPL(shrink_submounts); |
1da177e4 LT |
1325 | |
1326 | /* | |
1327 | * Some copy_from_user() implementations do not return the exact number of | |
1328 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. | |
1329 | * Note that this function differs from copy_from_user() in that it will oops | |
1330 | * on bad values of `to', rather than returning a short copy. | |
1331 | */ | |
b58fed8b RP |
1332 | static long exact_copy_from_user(void *to, const void __user * from, |
1333 | unsigned long n) | |
1da177e4 LT |
1334 | { |
1335 | char *t = to; | |
1336 | const char __user *f = from; | |
1337 | char c; | |
1338 | ||
1339 | if (!access_ok(VERIFY_READ, from, n)) | |
1340 | return n; | |
1341 | ||
1342 | while (n) { | |
1343 | if (__get_user(c, f)) { | |
1344 | memset(t, 0, n); | |
1345 | break; | |
1346 | } | |
1347 | *t++ = c; | |
1348 | f++; | |
1349 | n--; | |
1350 | } | |
1351 | return n; | |
1352 | } | |
1353 | ||
b58fed8b | 1354 | int copy_mount_options(const void __user * data, unsigned long *where) |
1da177e4 LT |
1355 | { |
1356 | int i; | |
1357 | unsigned long page; | |
1358 | unsigned long size; | |
b58fed8b | 1359 | |
1da177e4 LT |
1360 | *where = 0; |
1361 | if (!data) | |
1362 | return 0; | |
1363 | ||
1364 | if (!(page = __get_free_page(GFP_KERNEL))) | |
1365 | return -ENOMEM; | |
1366 | ||
1367 | /* We only care that *some* data at the address the user | |
1368 | * gave us is valid. Just in case, we'll zero | |
1369 | * the remainder of the page. | |
1370 | */ | |
1371 | /* copy_from_user cannot cross TASK_SIZE ! */ | |
1372 | size = TASK_SIZE - (unsigned long)data; | |
1373 | if (size > PAGE_SIZE) | |
1374 | size = PAGE_SIZE; | |
1375 | ||
1376 | i = size - exact_copy_from_user((void *)page, data, size); | |
1377 | if (!i) { | |
b58fed8b | 1378 | free_page(page); |
1da177e4 LT |
1379 | return -EFAULT; |
1380 | } | |
1381 | if (i != PAGE_SIZE) | |
1382 | memset((char *)page + i, 0, PAGE_SIZE - i); | |
1383 | *where = page; | |
1384 | return 0; | |
1385 | } | |
1386 | ||
1387 | /* | |
1388 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
1389 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
1390 | * | |
1391 | * data is a (void *) that can point to any structure up to | |
1392 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
1393 | * information (or be NULL). | |
1394 | * | |
1395 | * Pre-0.97 versions of mount() didn't have a flags word. | |
1396 | * When the flags word was introduced its top half was required | |
1397 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
1398 | * Therefore, if this magic number is present, it carries no information | |
1399 | * and must be discarded. | |
1400 | */ | |
b58fed8b | 1401 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
1da177e4 LT |
1402 | unsigned long flags, void *data_page) |
1403 | { | |
1404 | struct nameidata nd; | |
1405 | int retval = 0; | |
1406 | int mnt_flags = 0; | |
1407 | ||
1408 | /* Discard magic */ | |
1409 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
1410 | flags &= ~MS_MGC_MSK; | |
1411 | ||
1412 | /* Basic sanity checks */ | |
1413 | ||
1414 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) | |
1415 | return -EINVAL; | |
1416 | if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) | |
1417 | return -EINVAL; | |
1418 | ||
1419 | if (data_page) | |
1420 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
1421 | ||
1422 | /* Separate the per-mountpoint flags */ | |
1423 | if (flags & MS_NOSUID) | |
1424 | mnt_flags |= MNT_NOSUID; | |
1425 | if (flags & MS_NODEV) | |
1426 | mnt_flags |= MNT_NODEV; | |
1427 | if (flags & MS_NOEXEC) | |
1428 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
1429 | if (flags & MS_NOATIME) |
1430 | mnt_flags |= MNT_NOATIME; | |
1431 | if (flags & MS_NODIRATIME) | |
1432 | mnt_flags |= MNT_NODIRATIME; | |
47ae32d6 VH |
1433 | if (flags & MS_RELATIME) |
1434 | mnt_flags |= MNT_RELATIME; | |
fc33a7bb CH |
1435 | |
1436 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | | |
8bf9725c | 1437 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT); |
1da177e4 LT |
1438 | |
1439 | /* ... and get the mountpoint */ | |
1440 | retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); | |
1441 | if (retval) | |
1442 | return retval; | |
1443 | ||
1444 | retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page); | |
1445 | if (retval) | |
1446 | goto dput_out; | |
1447 | ||
1448 | if (flags & MS_REMOUNT) | |
1449 | retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, | |
1450 | data_page); | |
1451 | else if (flags & MS_BIND) | |
eee391a6 | 1452 | retval = do_loopback(&nd, dev_name, flags & MS_REC); |
9676f0c6 | 1453 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
07b20889 | 1454 | retval = do_change_type(&nd, flags); |
1da177e4 LT |
1455 | else if (flags & MS_MOVE) |
1456 | retval = do_move_mount(&nd, dev_name); | |
1457 | else | |
1458 | retval = do_new_mount(&nd, type_page, flags, mnt_flags, | |
1459 | dev_name, data_page); | |
1460 | dput_out: | |
1461 | path_release(&nd); | |
1462 | return retval; | |
1463 | } | |
1464 | ||
741a2951 JD |
1465 | /* |
1466 | * Allocate a new namespace structure and populate it with contents | |
1467 | * copied from the namespace of the passed in task structure. | |
1468 | */ | |
e3222c4e | 1469 | static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, |
6b3286ed | 1470 | struct fs_struct *fs) |
1da177e4 | 1471 | { |
6b3286ed | 1472 | struct mnt_namespace *new_ns; |
1da177e4 | 1473 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL; |
1da177e4 LT |
1474 | struct vfsmount *p, *q; |
1475 | ||
6b3286ed | 1476 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); |
1da177e4 | 1477 | if (!new_ns) |
467e9f4b | 1478 | return ERR_PTR(-ENOMEM); |
1da177e4 LT |
1479 | |
1480 | atomic_set(&new_ns->count, 1); | |
1da177e4 | 1481 | INIT_LIST_HEAD(&new_ns->list); |
5addc5dd AV |
1482 | init_waitqueue_head(&new_ns->poll); |
1483 | new_ns->event = 0; | |
1da177e4 | 1484 | |
390c6843 | 1485 | down_write(&namespace_sem); |
1da177e4 | 1486 | /* First pass: copy the tree topology */ |
6b3286ed | 1487 | new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root, |
9676f0c6 | 1488 | CL_COPY_ALL | CL_EXPIRE); |
1da177e4 | 1489 | if (!new_ns->root) { |
390c6843 | 1490 | up_write(&namespace_sem); |
1da177e4 | 1491 | kfree(new_ns); |
467e9f4b | 1492 | return ERR_PTR(-ENOMEM);; |
1da177e4 LT |
1493 | } |
1494 | spin_lock(&vfsmount_lock); | |
1495 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); | |
1496 | spin_unlock(&vfsmount_lock); | |
1497 | ||
1498 | /* | |
1499 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
1500 | * as belonging to new namespace. We have already acquired a private | |
1501 | * fs_struct, so tsk->fs->lock is not needed. | |
1502 | */ | |
6b3286ed | 1503 | p = mnt_ns->root; |
1da177e4 LT |
1504 | q = new_ns->root; |
1505 | while (p) { | |
6b3286ed | 1506 | q->mnt_ns = new_ns; |
1da177e4 LT |
1507 | if (fs) { |
1508 | if (p == fs->rootmnt) { | |
1509 | rootmnt = p; | |
1510 | fs->rootmnt = mntget(q); | |
1511 | } | |
1512 | if (p == fs->pwdmnt) { | |
1513 | pwdmnt = p; | |
1514 | fs->pwdmnt = mntget(q); | |
1515 | } | |
1516 | if (p == fs->altrootmnt) { | |
1517 | altrootmnt = p; | |
1518 | fs->altrootmnt = mntget(q); | |
1519 | } | |
1520 | } | |
6b3286ed | 1521 | p = next_mnt(p, mnt_ns->root); |
1da177e4 LT |
1522 | q = next_mnt(q, new_ns->root); |
1523 | } | |
390c6843 | 1524 | up_write(&namespace_sem); |
1da177e4 | 1525 | |
1da177e4 LT |
1526 | if (rootmnt) |
1527 | mntput(rootmnt); | |
1528 | if (pwdmnt) | |
1529 | mntput(pwdmnt); | |
1530 | if (altrootmnt) | |
1531 | mntput(altrootmnt); | |
1532 | ||
741a2951 JD |
1533 | return new_ns; |
1534 | } | |
1535 | ||
213dd266 | 1536 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
e3222c4e | 1537 | struct fs_struct *new_fs) |
741a2951 | 1538 | { |
6b3286ed | 1539 | struct mnt_namespace *new_ns; |
741a2951 | 1540 | |
e3222c4e | 1541 | BUG_ON(!ns); |
6b3286ed | 1542 | get_mnt_ns(ns); |
741a2951 JD |
1543 | |
1544 | if (!(flags & CLONE_NEWNS)) | |
e3222c4e | 1545 | return ns; |
741a2951 | 1546 | |
e3222c4e | 1547 | new_ns = dup_mnt_ns(ns, new_fs); |
741a2951 | 1548 | |
6b3286ed | 1549 | put_mnt_ns(ns); |
e3222c4e | 1550 | return new_ns; |
1da177e4 LT |
1551 | } |
1552 | ||
1553 | asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name, | |
1554 | char __user * type, unsigned long flags, | |
1555 | void __user * data) | |
1556 | { | |
1557 | int retval; | |
1558 | unsigned long data_page; | |
1559 | unsigned long type_page; | |
1560 | unsigned long dev_page; | |
1561 | char *dir_page; | |
1562 | ||
b58fed8b | 1563 | retval = copy_mount_options(type, &type_page); |
1da177e4 LT |
1564 | if (retval < 0) |
1565 | return retval; | |
1566 | ||
1567 | dir_page = getname(dir_name); | |
1568 | retval = PTR_ERR(dir_page); | |
1569 | if (IS_ERR(dir_page)) | |
1570 | goto out1; | |
1571 | ||
b58fed8b | 1572 | retval = copy_mount_options(dev_name, &dev_page); |
1da177e4 LT |
1573 | if (retval < 0) |
1574 | goto out2; | |
1575 | ||
b58fed8b | 1576 | retval = copy_mount_options(data, &data_page); |
1da177e4 LT |
1577 | if (retval < 0) |
1578 | goto out3; | |
1579 | ||
1580 | lock_kernel(); | |
b58fed8b RP |
1581 | retval = do_mount((char *)dev_page, dir_page, (char *)type_page, |
1582 | flags, (void *)data_page); | |
1da177e4 LT |
1583 | unlock_kernel(); |
1584 | free_page(data_page); | |
1585 | ||
1586 | out3: | |
1587 | free_page(dev_page); | |
1588 | out2: | |
1589 | putname(dir_page); | |
1590 | out1: | |
1591 | free_page(type_page); | |
1592 | return retval; | |
1593 | } | |
1594 | ||
1595 | /* | |
1596 | * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. | |
1597 | * It can block. Requires the big lock held. | |
1598 | */ | |
1599 | void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt, | |
1600 | struct dentry *dentry) | |
1601 | { | |
1602 | struct dentry *old_root; | |
1603 | struct vfsmount *old_rootmnt; | |
1604 | write_lock(&fs->lock); | |
1605 | old_root = fs->root; | |
1606 | old_rootmnt = fs->rootmnt; | |
1607 | fs->rootmnt = mntget(mnt); | |
1608 | fs->root = dget(dentry); | |
1609 | write_unlock(&fs->lock); | |
1610 | if (old_root) { | |
1611 | dput(old_root); | |
1612 | mntput(old_rootmnt); | |
1613 | } | |
1614 | } | |
1615 | ||
1616 | /* | |
1617 | * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. | |
1618 | * It can block. Requires the big lock held. | |
1619 | */ | |
1620 | void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, | |
1621 | struct dentry *dentry) | |
1622 | { | |
1623 | struct dentry *old_pwd; | |
1624 | struct vfsmount *old_pwdmnt; | |
1625 | ||
1626 | write_lock(&fs->lock); | |
1627 | old_pwd = fs->pwd; | |
1628 | old_pwdmnt = fs->pwdmnt; | |
1629 | fs->pwdmnt = mntget(mnt); | |
1630 | fs->pwd = dget(dentry); | |
1631 | write_unlock(&fs->lock); | |
1632 | ||
1633 | if (old_pwd) { | |
1634 | dput(old_pwd); | |
1635 | mntput(old_pwdmnt); | |
1636 | } | |
1637 | } | |
1638 | ||
1639 | static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) | |
1640 | { | |
1641 | struct task_struct *g, *p; | |
1642 | struct fs_struct *fs; | |
1643 | ||
1644 | read_lock(&tasklist_lock); | |
1645 | do_each_thread(g, p) { | |
1646 | task_lock(p); | |
1647 | fs = p->fs; | |
1648 | if (fs) { | |
1649 | atomic_inc(&fs->count); | |
1650 | task_unlock(p); | |
b58fed8b RP |
1651 | if (fs->root == old_nd->dentry |
1652 | && fs->rootmnt == old_nd->mnt) | |
1da177e4 | 1653 | set_fs_root(fs, new_nd->mnt, new_nd->dentry); |
b58fed8b RP |
1654 | if (fs->pwd == old_nd->dentry |
1655 | && fs->pwdmnt == old_nd->mnt) | |
1da177e4 LT |
1656 | set_fs_pwd(fs, new_nd->mnt, new_nd->dentry); |
1657 | put_fs_struct(fs); | |
1658 | } else | |
1659 | task_unlock(p); | |
1660 | } while_each_thread(g, p); | |
1661 | read_unlock(&tasklist_lock); | |
1662 | } | |
1663 | ||
1664 | /* | |
1665 | * pivot_root Semantics: | |
1666 | * Moves the root file system of the current process to the directory put_old, | |
1667 | * makes new_root as the new root file system of the current process, and sets | |
1668 | * root/cwd of all processes which had them on the current root to new_root. | |
1669 | * | |
1670 | * Restrictions: | |
1671 | * The new_root and put_old must be directories, and must not be on the | |
1672 | * same file system as the current process root. The put_old must be | |
1673 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
1674 | * pointed to by put_old must yield the same directory as new_root. No other | |
1675 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
1676 | * | |
4a0d11fa NB |
1677 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
1678 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives | |
1679 | * in this situation. | |
1680 | * | |
1da177e4 LT |
1681 | * Notes: |
1682 | * - we don't move root/cwd if they are not at the root (reason: if something | |
1683 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
1684 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
1685 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
1686 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
1687 | * first. | |
1688 | */ | |
b58fed8b RP |
1689 | asmlinkage long sys_pivot_root(const char __user * new_root, |
1690 | const char __user * put_old) | |
1da177e4 LT |
1691 | { |
1692 | struct vfsmount *tmp; | |
1693 | struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; | |
1694 | int error; | |
1695 | ||
1696 | if (!capable(CAP_SYS_ADMIN)) | |
1697 | return -EPERM; | |
1698 | ||
1699 | lock_kernel(); | |
1700 | ||
b58fed8b RP |
1701 | error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, |
1702 | &new_nd); | |
1da177e4 LT |
1703 | if (error) |
1704 | goto out0; | |
1705 | error = -EINVAL; | |
1706 | if (!check_mnt(new_nd.mnt)) | |
1707 | goto out1; | |
1708 | ||
b58fed8b | 1709 | error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd); |
1da177e4 LT |
1710 | if (error) |
1711 | goto out1; | |
1712 | ||
1713 | error = security_sb_pivotroot(&old_nd, &new_nd); | |
1714 | if (error) { | |
1715 | path_release(&old_nd); | |
1716 | goto out1; | |
1717 | } | |
1718 | ||
1719 | read_lock(¤t->fs->lock); | |
1720 | user_nd.mnt = mntget(current->fs->rootmnt); | |
1721 | user_nd.dentry = dget(current->fs->root); | |
1722 | read_unlock(¤t->fs->lock); | |
390c6843 | 1723 | down_write(&namespace_sem); |
1b1dcc1b | 1724 | mutex_lock(&old_nd.dentry->d_inode->i_mutex); |
1da177e4 | 1725 | error = -EINVAL; |
21444403 RP |
1726 | if (IS_MNT_SHARED(old_nd.mnt) || |
1727 | IS_MNT_SHARED(new_nd.mnt->mnt_parent) || | |
1728 | IS_MNT_SHARED(user_nd.mnt->mnt_parent)) | |
1729 | goto out2; | |
1da177e4 LT |
1730 | if (!check_mnt(user_nd.mnt)) |
1731 | goto out2; | |
1732 | error = -ENOENT; | |
1733 | if (IS_DEADDIR(new_nd.dentry->d_inode)) | |
1734 | goto out2; | |
1735 | if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry)) | |
1736 | goto out2; | |
1737 | if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry)) | |
1738 | goto out2; | |
1739 | error = -EBUSY; | |
1740 | if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt) | |
1741 | goto out2; /* loop, on the same file system */ | |
1742 | error = -EINVAL; | |
1743 | if (user_nd.mnt->mnt_root != user_nd.dentry) | |
1744 | goto out2; /* not a mountpoint */ | |
0bb6fcc1 MS |
1745 | if (user_nd.mnt->mnt_parent == user_nd.mnt) |
1746 | goto out2; /* not attached */ | |
1da177e4 LT |
1747 | if (new_nd.mnt->mnt_root != new_nd.dentry) |
1748 | goto out2; /* not a mountpoint */ | |
0bb6fcc1 MS |
1749 | if (new_nd.mnt->mnt_parent == new_nd.mnt) |
1750 | goto out2; /* not attached */ | |
1da177e4 LT |
1751 | tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */ |
1752 | spin_lock(&vfsmount_lock); | |
1753 | if (tmp != new_nd.mnt) { | |
1754 | for (;;) { | |
1755 | if (tmp->mnt_parent == tmp) | |
1756 | goto out3; /* already mounted on put_old */ | |
1757 | if (tmp->mnt_parent == new_nd.mnt) | |
1758 | break; | |
1759 | tmp = tmp->mnt_parent; | |
1760 | } | |
1761 | if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry)) | |
1762 | goto out3; | |
1763 | } else if (!is_subdir(old_nd.dentry, new_nd.dentry)) | |
1764 | goto out3; | |
1765 | detach_mnt(new_nd.mnt, &parent_nd); | |
1766 | detach_mnt(user_nd.mnt, &root_parent); | |
1767 | attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ | |
1768 | attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ | |
6b3286ed | 1769 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
1da177e4 LT |
1770 | spin_unlock(&vfsmount_lock); |
1771 | chroot_fs_refs(&user_nd, &new_nd); | |
1772 | security_sb_post_pivotroot(&user_nd, &new_nd); | |
1773 | error = 0; | |
1774 | path_release(&root_parent); | |
1775 | path_release(&parent_nd); | |
1776 | out2: | |
1b1dcc1b | 1777 | mutex_unlock(&old_nd.dentry->d_inode->i_mutex); |
390c6843 | 1778 | up_write(&namespace_sem); |
1da177e4 LT |
1779 | path_release(&user_nd); |
1780 | path_release(&old_nd); | |
1781 | out1: | |
1782 | path_release(&new_nd); | |
1783 | out0: | |
1784 | unlock_kernel(); | |
1785 | return error; | |
1786 | out3: | |
1787 | spin_unlock(&vfsmount_lock); | |
1788 | goto out2; | |
1789 | } | |
1790 | ||
1791 | static void __init init_mount_tree(void) | |
1792 | { | |
1793 | struct vfsmount *mnt; | |
6b3286ed | 1794 | struct mnt_namespace *ns; |
1da177e4 LT |
1795 | |
1796 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); | |
1797 | if (IS_ERR(mnt)) | |
1798 | panic("Can't create rootfs"); | |
6b3286ed KK |
1799 | ns = kmalloc(sizeof(*ns), GFP_KERNEL); |
1800 | if (!ns) | |
1da177e4 | 1801 | panic("Can't allocate initial namespace"); |
6b3286ed KK |
1802 | atomic_set(&ns->count, 1); |
1803 | INIT_LIST_HEAD(&ns->list); | |
1804 | init_waitqueue_head(&ns->poll); | |
1805 | ns->event = 0; | |
1806 | list_add(&mnt->mnt_list, &ns->list); | |
1807 | ns->root = mnt; | |
1808 | mnt->mnt_ns = ns; | |
1809 | ||
1810 | init_task.nsproxy->mnt_ns = ns; | |
1811 | get_mnt_ns(ns); | |
1812 | ||
1813 | set_fs_pwd(current->fs, ns->root, ns->root->mnt_root); | |
1814 | set_fs_root(current->fs, ns->root, ns->root->mnt_root); | |
1da177e4 LT |
1815 | } |
1816 | ||
74bf17cf | 1817 | void __init mnt_init(void) |
1da177e4 | 1818 | { |
13f14b4d | 1819 | unsigned u; |
15a67dd8 | 1820 | int err; |
1da177e4 | 1821 | |
390c6843 RP |
1822 | init_rwsem(&namespace_sem); |
1823 | ||
1da177e4 | 1824 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), |
20c2df83 | 1825 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
1da177e4 | 1826 | |
b58fed8b | 1827 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
1da177e4 LT |
1828 | |
1829 | if (!mount_hashtable) | |
1830 | panic("Failed to allocate mount hash table\n"); | |
1831 | ||
13f14b4d ED |
1832 | printk("Mount-cache hash table entries: %lu\n", HASH_SIZE); |
1833 | ||
1834 | for (u = 0; u < HASH_SIZE; u++) | |
1835 | INIT_LIST_HEAD(&mount_hashtable[u]); | |
1da177e4 | 1836 | |
15a67dd8 RD |
1837 | err = sysfs_init(); |
1838 | if (err) | |
1839 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", | |
1840 | __FUNCTION__, err); | |
00d26666 GKH |
1841 | fs_kobj = kobject_create_and_add("fs", NULL); |
1842 | if (!fs_kobj) | |
1843 | printk(KERN_WARNING "%s: kobj create error\n", __FUNCTION__); | |
1da177e4 LT |
1844 | init_rootfs(); |
1845 | init_mount_tree(); | |
1846 | } | |
1847 | ||
6b3286ed | 1848 | void __put_mnt_ns(struct mnt_namespace *ns) |
1da177e4 | 1849 | { |
6b3286ed | 1850 | struct vfsmount *root = ns->root; |
70fbcdf4 | 1851 | LIST_HEAD(umount_list); |
6b3286ed | 1852 | ns->root = NULL; |
1ce88cf4 | 1853 | spin_unlock(&vfsmount_lock); |
390c6843 | 1854 | down_write(&namespace_sem); |
1da177e4 | 1855 | spin_lock(&vfsmount_lock); |
a05964f3 | 1856 | umount_tree(root, 0, &umount_list); |
1da177e4 | 1857 | spin_unlock(&vfsmount_lock); |
390c6843 | 1858 | up_write(&namespace_sem); |
70fbcdf4 | 1859 | release_mounts(&umount_list); |
6b3286ed | 1860 | kfree(ns); |
1da177e4 | 1861 | } |