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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> | |
19 | #include <linux/module.h> | |
20 | #include <linux/seq_file.h> | |
21 | #include <linux/namespace.h> | |
22 | #include <linux/namei.h> | |
23 | #include <linux/security.h> | |
24 | #include <linux/mount.h> | |
25 | #include <asm/uaccess.h> | |
26 | #include <asm/unistd.h> | |
07b20889 | 27 | #include "pnode.h" |
1da177e4 LT |
28 | |
29 | extern int __init init_rootfs(void); | |
30 | ||
36341f64 RP |
31 | #define CL_EXPIRE 0x01 |
32 | ||
1da177e4 LT |
33 | #ifdef CONFIG_SYSFS |
34 | extern int __init sysfs_init(void); | |
35 | #else | |
36 | static inline int sysfs_init(void) | |
37 | { | |
38 | return 0; | |
39 | } | |
40 | #endif | |
41 | ||
42 | /* spinlock for vfsmount related operations, inplace of dcache_lock */ | |
5addc5dd AV |
43 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); |
44 | ||
45 | static int event; | |
1da177e4 LT |
46 | |
47 | static struct list_head *mount_hashtable; | |
6c231b7b | 48 | static int hash_mask __read_mostly, hash_bits __read_mostly; |
b58fed8b | 49 | static kmem_cache_t *mnt_cache; |
390c6843 | 50 | static struct rw_semaphore namespace_sem; |
1da177e4 LT |
51 | |
52 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) | |
53 | { | |
b58fed8b RP |
54 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
55 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
1da177e4 LT |
56 | tmp = tmp + (tmp >> hash_bits); |
57 | return tmp & hash_mask; | |
58 | } | |
59 | ||
60 | struct vfsmount *alloc_vfsmnt(const char *name) | |
61 | { | |
b58fed8b | 62 | struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL); |
1da177e4 LT |
63 | if (mnt) { |
64 | memset(mnt, 0, sizeof(struct vfsmount)); | |
b58fed8b | 65 | atomic_set(&mnt->mnt_count, 1); |
1da177e4 LT |
66 | INIT_LIST_HEAD(&mnt->mnt_hash); |
67 | INIT_LIST_HEAD(&mnt->mnt_child); | |
68 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
69 | INIT_LIST_HEAD(&mnt->mnt_list); | |
55e700b9 | 70 | INIT_LIST_HEAD(&mnt->mnt_expire); |
03e06e68 | 71 | INIT_LIST_HEAD(&mnt->mnt_share); |
1da177e4 | 72 | if (name) { |
b58fed8b | 73 | int size = strlen(name) + 1; |
1da177e4 LT |
74 | char *newname = kmalloc(size, GFP_KERNEL); |
75 | if (newname) { | |
76 | memcpy(newname, name, size); | |
77 | mnt->mnt_devname = newname; | |
78 | } | |
79 | } | |
80 | } | |
81 | return mnt; | |
82 | } | |
83 | ||
84 | void free_vfsmnt(struct vfsmount *mnt) | |
85 | { | |
86 | kfree(mnt->mnt_devname); | |
87 | kmem_cache_free(mnt_cache, mnt); | |
88 | } | |
89 | ||
90 | /* | |
91 | * Now, lookup_mnt increments the ref count before returning | |
92 | * the vfsmount struct. | |
93 | */ | |
94 | struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) | |
95 | { | |
b58fed8b RP |
96 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
97 | struct list_head *tmp = head; | |
1da177e4 LT |
98 | struct vfsmount *p, *found = NULL; |
99 | ||
100 | spin_lock(&vfsmount_lock); | |
101 | for (;;) { | |
102 | tmp = tmp->next; | |
103 | p = NULL; | |
104 | if (tmp == head) | |
105 | break; | |
106 | p = list_entry(tmp, struct vfsmount, mnt_hash); | |
107 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { | |
108 | found = mntget(p); | |
109 | break; | |
110 | } | |
111 | } | |
112 | spin_unlock(&vfsmount_lock); | |
113 | return found; | |
114 | } | |
115 | ||
116 | static inline int check_mnt(struct vfsmount *mnt) | |
117 | { | |
118 | return mnt->mnt_namespace == current->namespace; | |
119 | } | |
120 | ||
5addc5dd AV |
121 | static void touch_namespace(struct namespace *ns) |
122 | { | |
123 | if (ns) { | |
124 | ns->event = ++event; | |
125 | wake_up_interruptible(&ns->poll); | |
126 | } | |
127 | } | |
128 | ||
129 | static void __touch_namespace(struct namespace *ns) | |
130 | { | |
131 | if (ns && ns->event != event) { | |
132 | ns->event = event; | |
133 | wake_up_interruptible(&ns->poll); | |
134 | } | |
135 | } | |
136 | ||
1da177e4 LT |
137 | static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) |
138 | { | |
139 | old_nd->dentry = mnt->mnt_mountpoint; | |
140 | old_nd->mnt = mnt->mnt_parent; | |
141 | mnt->mnt_parent = mnt; | |
142 | mnt->mnt_mountpoint = mnt->mnt_root; | |
143 | list_del_init(&mnt->mnt_child); | |
144 | list_del_init(&mnt->mnt_hash); | |
145 | old_nd->dentry->d_mounted--; | |
146 | } | |
147 | ||
148 | static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) | |
149 | { | |
150 | mnt->mnt_parent = mntget(nd->mnt); | |
151 | mnt->mnt_mountpoint = dget(nd->dentry); | |
b58fed8b | 152 | list_add(&mnt->mnt_hash, mount_hashtable + hash(nd->mnt, nd->dentry)); |
1da177e4 LT |
153 | list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts); |
154 | nd->dentry->d_mounted++; | |
155 | } | |
156 | ||
157 | static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) | |
158 | { | |
159 | struct list_head *next = p->mnt_mounts.next; | |
160 | if (next == &p->mnt_mounts) { | |
161 | while (1) { | |
162 | if (p == root) | |
163 | return NULL; | |
164 | next = p->mnt_child.next; | |
165 | if (next != &p->mnt_parent->mnt_mounts) | |
166 | break; | |
167 | p = p->mnt_parent; | |
168 | } | |
169 | } | |
170 | return list_entry(next, struct vfsmount, mnt_child); | |
171 | } | |
172 | ||
36341f64 RP |
173 | static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, |
174 | int flag) | |
1da177e4 LT |
175 | { |
176 | struct super_block *sb = old->mnt_sb; | |
177 | struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); | |
178 | ||
179 | if (mnt) { | |
180 | mnt->mnt_flags = old->mnt_flags; | |
181 | atomic_inc(&sb->s_active); | |
182 | mnt->mnt_sb = sb; | |
183 | mnt->mnt_root = dget(root); | |
184 | mnt->mnt_mountpoint = mnt->mnt_root; | |
185 | mnt->mnt_parent = mnt; | |
68b47139 | 186 | mnt->mnt_namespace = current->namespace; |
1da177e4 LT |
187 | |
188 | /* stick the duplicate mount on the same expiry list | |
189 | * as the original if that was on one */ | |
36341f64 RP |
190 | if (flag & CL_EXPIRE) { |
191 | spin_lock(&vfsmount_lock); | |
192 | if (!list_empty(&old->mnt_expire)) | |
193 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
194 | spin_unlock(&vfsmount_lock); | |
195 | } | |
1da177e4 LT |
196 | } |
197 | return mnt; | |
198 | } | |
199 | ||
7b7b1ace | 200 | static inline void __mntput(struct vfsmount *mnt) |
1da177e4 LT |
201 | { |
202 | struct super_block *sb = mnt->mnt_sb; | |
203 | dput(mnt->mnt_root); | |
204 | free_vfsmnt(mnt); | |
205 | deactivate_super(sb); | |
206 | } | |
207 | ||
7b7b1ace AV |
208 | void mntput_no_expire(struct vfsmount *mnt) |
209 | { | |
210 | repeat: | |
211 | if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { | |
212 | if (likely(!mnt->mnt_pinned)) { | |
213 | spin_unlock(&vfsmount_lock); | |
214 | __mntput(mnt); | |
215 | return; | |
216 | } | |
217 | atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); | |
218 | mnt->mnt_pinned = 0; | |
219 | spin_unlock(&vfsmount_lock); | |
220 | acct_auto_close_mnt(mnt); | |
221 | security_sb_umount_close(mnt); | |
222 | goto repeat; | |
223 | } | |
224 | } | |
225 | ||
226 | EXPORT_SYMBOL(mntput_no_expire); | |
227 | ||
228 | void mnt_pin(struct vfsmount *mnt) | |
229 | { | |
230 | spin_lock(&vfsmount_lock); | |
231 | mnt->mnt_pinned++; | |
232 | spin_unlock(&vfsmount_lock); | |
233 | } | |
234 | ||
235 | EXPORT_SYMBOL(mnt_pin); | |
236 | ||
237 | void mnt_unpin(struct vfsmount *mnt) | |
238 | { | |
239 | spin_lock(&vfsmount_lock); | |
240 | if (mnt->mnt_pinned) { | |
241 | atomic_inc(&mnt->mnt_count); | |
242 | mnt->mnt_pinned--; | |
243 | } | |
244 | spin_unlock(&vfsmount_lock); | |
245 | } | |
246 | ||
247 | EXPORT_SYMBOL(mnt_unpin); | |
1da177e4 LT |
248 | |
249 | /* iterator */ | |
250 | static void *m_start(struct seq_file *m, loff_t *pos) | |
251 | { | |
252 | struct namespace *n = m->private; | |
253 | struct list_head *p; | |
254 | loff_t l = *pos; | |
255 | ||
390c6843 | 256 | down_read(&namespace_sem); |
1da177e4 LT |
257 | list_for_each(p, &n->list) |
258 | if (!l--) | |
259 | return list_entry(p, struct vfsmount, mnt_list); | |
260 | return NULL; | |
261 | } | |
262 | ||
263 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
264 | { | |
265 | struct namespace *n = m->private; | |
266 | struct list_head *p = ((struct vfsmount *)v)->mnt_list.next; | |
267 | (*pos)++; | |
b58fed8b | 268 | return p == &n->list ? NULL : list_entry(p, struct vfsmount, mnt_list); |
1da177e4 LT |
269 | } |
270 | ||
271 | static void m_stop(struct seq_file *m, void *v) | |
272 | { | |
390c6843 | 273 | up_read(&namespace_sem); |
1da177e4 LT |
274 | } |
275 | ||
276 | static inline void mangle(struct seq_file *m, const char *s) | |
277 | { | |
278 | seq_escape(m, s, " \t\n\\"); | |
279 | } | |
280 | ||
281 | static int show_vfsmnt(struct seq_file *m, void *v) | |
282 | { | |
283 | struct vfsmount *mnt = v; | |
284 | int err = 0; | |
285 | static struct proc_fs_info { | |
286 | int flag; | |
287 | char *str; | |
288 | } fs_info[] = { | |
289 | { MS_SYNCHRONOUS, ",sync" }, | |
290 | { MS_DIRSYNC, ",dirsync" }, | |
291 | { MS_MANDLOCK, ",mand" }, | |
292 | { MS_NOATIME, ",noatime" }, | |
293 | { MS_NODIRATIME, ",nodiratime" }, | |
294 | { 0, NULL } | |
295 | }; | |
296 | static struct proc_fs_info mnt_info[] = { | |
297 | { MNT_NOSUID, ",nosuid" }, | |
298 | { MNT_NODEV, ",nodev" }, | |
299 | { MNT_NOEXEC, ",noexec" }, | |
300 | { 0, NULL } | |
301 | }; | |
302 | struct proc_fs_info *fs_infop; | |
303 | ||
304 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
305 | seq_putc(m, ' '); | |
306 | seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); | |
307 | seq_putc(m, ' '); | |
308 | mangle(m, mnt->mnt_sb->s_type->name); | |
309 | seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); | |
310 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { | |
311 | if (mnt->mnt_sb->s_flags & fs_infop->flag) | |
312 | seq_puts(m, fs_infop->str); | |
313 | } | |
314 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { | |
315 | if (mnt->mnt_flags & fs_infop->flag) | |
316 | seq_puts(m, fs_infop->str); | |
317 | } | |
318 | if (mnt->mnt_sb->s_op->show_options) | |
319 | err = mnt->mnt_sb->s_op->show_options(m, mnt); | |
320 | seq_puts(m, " 0 0\n"); | |
321 | return err; | |
322 | } | |
323 | ||
324 | struct seq_operations mounts_op = { | |
325 | .start = m_start, | |
326 | .next = m_next, | |
327 | .stop = m_stop, | |
328 | .show = show_vfsmnt | |
329 | }; | |
330 | ||
331 | /** | |
332 | * may_umount_tree - check if a mount tree is busy | |
333 | * @mnt: root of mount tree | |
334 | * | |
335 | * This is called to check if a tree of mounts has any | |
336 | * open files, pwds, chroots or sub mounts that are | |
337 | * busy. | |
338 | */ | |
339 | int may_umount_tree(struct vfsmount *mnt) | |
340 | { | |
36341f64 RP |
341 | int actual_refs = 0; |
342 | int minimum_refs = 0; | |
343 | struct vfsmount *p; | |
1da177e4 LT |
344 | |
345 | spin_lock(&vfsmount_lock); | |
36341f64 | 346 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
1da177e4 LT |
347 | actual_refs += atomic_read(&p->mnt_count); |
348 | minimum_refs += 2; | |
1da177e4 LT |
349 | } |
350 | spin_unlock(&vfsmount_lock); | |
351 | ||
352 | if (actual_refs > minimum_refs) | |
353 | return -EBUSY; | |
354 | ||
355 | return 0; | |
356 | } | |
357 | ||
358 | EXPORT_SYMBOL(may_umount_tree); | |
359 | ||
360 | /** | |
361 | * may_umount - check if a mount point is busy | |
362 | * @mnt: root of mount | |
363 | * | |
364 | * This is called to check if a mount point has any | |
365 | * open files, pwds, chroots or sub mounts. If the | |
366 | * mount has sub mounts this will return busy | |
367 | * regardless of whether the sub mounts are busy. | |
368 | * | |
369 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
370 | * give false negatives. The main reason why it's here is that we need | |
371 | * a non-destructive way to look for easily umountable filesystems. | |
372 | */ | |
373 | int may_umount(struct vfsmount *mnt) | |
374 | { | |
375 | if (atomic_read(&mnt->mnt_count) > 2) | |
376 | return -EBUSY; | |
377 | return 0; | |
378 | } | |
379 | ||
380 | EXPORT_SYMBOL(may_umount); | |
381 | ||
70fbcdf4 RP |
382 | static void release_mounts(struct list_head *head) |
383 | { | |
384 | struct vfsmount *mnt; | |
385 | while(!list_empty(head)) { | |
386 | mnt = list_entry(head->next, struct vfsmount, mnt_hash); | |
387 | list_del_init(&mnt->mnt_hash); | |
388 | if (mnt->mnt_parent != mnt) { | |
389 | struct dentry *dentry; | |
390 | struct vfsmount *m; | |
391 | spin_lock(&vfsmount_lock); | |
392 | dentry = mnt->mnt_mountpoint; | |
393 | m = mnt->mnt_parent; | |
394 | mnt->mnt_mountpoint = mnt->mnt_root; | |
395 | mnt->mnt_parent = mnt; | |
396 | spin_unlock(&vfsmount_lock); | |
397 | dput(dentry); | |
398 | mntput(m); | |
399 | } | |
400 | mntput(mnt); | |
401 | } | |
402 | } | |
403 | ||
404 | static void umount_tree(struct vfsmount *mnt, struct list_head *kill) | |
1da177e4 LT |
405 | { |
406 | struct vfsmount *p; | |
1da177e4 LT |
407 | |
408 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
70fbcdf4 RP |
409 | list_del(&p->mnt_hash); |
410 | list_add(&p->mnt_hash, kill); | |
1da177e4 LT |
411 | } |
412 | ||
70fbcdf4 RP |
413 | list_for_each_entry(p, kill, mnt_hash) { |
414 | list_del_init(&p->mnt_expire); | |
415 | list_del_init(&p->mnt_list); | |
416 | __touch_namespace(p->mnt_namespace); | |
417 | p->mnt_namespace = NULL; | |
418 | list_del_init(&p->mnt_child); | |
419 | if (p->mnt_parent != p) | |
420 | mnt->mnt_mountpoint->d_mounted--; | |
1da177e4 LT |
421 | } |
422 | } | |
423 | ||
424 | static int do_umount(struct vfsmount *mnt, int flags) | |
425 | { | |
b58fed8b | 426 | struct super_block *sb = mnt->mnt_sb; |
1da177e4 | 427 | int retval; |
70fbcdf4 | 428 | LIST_HEAD(umount_list); |
1da177e4 LT |
429 | |
430 | retval = security_sb_umount(mnt, flags); | |
431 | if (retval) | |
432 | return retval; | |
433 | ||
434 | /* | |
435 | * Allow userspace to request a mountpoint be expired rather than | |
436 | * unmounting unconditionally. Unmount only happens if: | |
437 | * (1) the mark is already set (the mark is cleared by mntput()) | |
438 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
439 | */ | |
440 | if (flags & MNT_EXPIRE) { | |
441 | if (mnt == current->fs->rootmnt || | |
442 | flags & (MNT_FORCE | MNT_DETACH)) | |
443 | return -EINVAL; | |
444 | ||
445 | if (atomic_read(&mnt->mnt_count) != 2) | |
446 | return -EBUSY; | |
447 | ||
448 | if (!xchg(&mnt->mnt_expiry_mark, 1)) | |
449 | return -EAGAIN; | |
450 | } | |
451 | ||
452 | /* | |
453 | * If we may have to abort operations to get out of this | |
454 | * mount, and they will themselves hold resources we must | |
455 | * allow the fs to do things. In the Unix tradition of | |
456 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
457 | * might fail to complete on the first run through as other tasks | |
458 | * must return, and the like. Thats for the mount program to worry | |
459 | * about for the moment. | |
460 | */ | |
461 | ||
462 | lock_kernel(); | |
b58fed8b | 463 | if ((flags & MNT_FORCE) && sb->s_op->umount_begin) |
1da177e4 LT |
464 | sb->s_op->umount_begin(sb); |
465 | unlock_kernel(); | |
466 | ||
467 | /* | |
468 | * No sense to grab the lock for this test, but test itself looks | |
469 | * somewhat bogus. Suggestions for better replacement? | |
470 | * Ho-hum... In principle, we might treat that as umount + switch | |
471 | * to rootfs. GC would eventually take care of the old vfsmount. | |
472 | * Actually it makes sense, especially if rootfs would contain a | |
473 | * /reboot - static binary that would close all descriptors and | |
474 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
475 | */ | |
476 | if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) { | |
477 | /* | |
478 | * Special case for "unmounting" root ... | |
479 | * we just try to remount it readonly. | |
480 | */ | |
481 | down_write(&sb->s_umount); | |
482 | if (!(sb->s_flags & MS_RDONLY)) { | |
483 | lock_kernel(); | |
484 | DQUOT_OFF(sb); | |
485 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); | |
486 | unlock_kernel(); | |
487 | } | |
488 | up_write(&sb->s_umount); | |
489 | return retval; | |
490 | } | |
491 | ||
390c6843 | 492 | down_write(&namespace_sem); |
1da177e4 | 493 | spin_lock(&vfsmount_lock); |
5addc5dd | 494 | event++; |
1da177e4 | 495 | |
1da177e4 LT |
496 | retval = -EBUSY; |
497 | if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) { | |
498 | if (!list_empty(&mnt->mnt_list)) | |
70fbcdf4 | 499 | umount_tree(mnt, &umount_list); |
1da177e4 LT |
500 | retval = 0; |
501 | } | |
502 | spin_unlock(&vfsmount_lock); | |
503 | if (retval) | |
504 | security_sb_umount_busy(mnt); | |
390c6843 | 505 | up_write(&namespace_sem); |
70fbcdf4 | 506 | release_mounts(&umount_list); |
1da177e4 LT |
507 | return retval; |
508 | } | |
509 | ||
510 | /* | |
511 | * Now umount can handle mount points as well as block devices. | |
512 | * This is important for filesystems which use unnamed block devices. | |
513 | * | |
514 | * We now support a flag for forced unmount like the other 'big iron' | |
515 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD | |
516 | */ | |
517 | ||
518 | asmlinkage long sys_umount(char __user * name, int flags) | |
519 | { | |
520 | struct nameidata nd; | |
521 | int retval; | |
522 | ||
523 | retval = __user_walk(name, LOOKUP_FOLLOW, &nd); | |
524 | if (retval) | |
525 | goto out; | |
526 | retval = -EINVAL; | |
527 | if (nd.dentry != nd.mnt->mnt_root) | |
528 | goto dput_and_out; | |
529 | if (!check_mnt(nd.mnt)) | |
530 | goto dput_and_out; | |
531 | ||
532 | retval = -EPERM; | |
533 | if (!capable(CAP_SYS_ADMIN)) | |
534 | goto dput_and_out; | |
535 | ||
536 | retval = do_umount(nd.mnt, flags); | |
537 | dput_and_out: | |
538 | path_release_on_umount(&nd); | |
539 | out: | |
540 | return retval; | |
541 | } | |
542 | ||
543 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT | |
544 | ||
545 | /* | |
b58fed8b | 546 | * The 2.0 compatible umount. No flags. |
1da177e4 | 547 | */ |
1da177e4 LT |
548 | asmlinkage long sys_oldumount(char __user * name) |
549 | { | |
b58fed8b | 550 | return sys_umount(name, 0); |
1da177e4 LT |
551 | } |
552 | ||
553 | #endif | |
554 | ||
555 | static int mount_is_safe(struct nameidata *nd) | |
556 | { | |
557 | if (capable(CAP_SYS_ADMIN)) | |
558 | return 0; | |
559 | return -EPERM; | |
560 | #ifdef notyet | |
561 | if (S_ISLNK(nd->dentry->d_inode->i_mode)) | |
562 | return -EPERM; | |
563 | if (nd->dentry->d_inode->i_mode & S_ISVTX) { | |
564 | if (current->uid != nd->dentry->d_inode->i_uid) | |
565 | return -EPERM; | |
566 | } | |
567 | if (permission(nd->dentry->d_inode, MAY_WRITE, nd)) | |
568 | return -EPERM; | |
569 | return 0; | |
570 | #endif | |
571 | } | |
572 | ||
b58fed8b | 573 | static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry) |
1da177e4 LT |
574 | { |
575 | while (1) { | |
576 | if (d == dentry) | |
577 | return 1; | |
578 | if (d == NULL || d == d->d_parent) | |
579 | return 0; | |
580 | d = d->d_parent; | |
581 | } | |
582 | } | |
583 | ||
36341f64 RP |
584 | static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, |
585 | int flag) | |
1da177e4 LT |
586 | { |
587 | struct vfsmount *res, *p, *q, *r, *s; | |
1da177e4 LT |
588 | struct nameidata nd; |
589 | ||
36341f64 | 590 | res = q = clone_mnt(mnt, dentry, flag); |
1da177e4 LT |
591 | if (!q) |
592 | goto Enomem; | |
593 | q->mnt_mountpoint = mnt->mnt_mountpoint; | |
594 | ||
595 | p = mnt; | |
fdadd65f | 596 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
1da177e4 LT |
597 | if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry)) |
598 | continue; | |
599 | ||
600 | for (s = r; s; s = next_mnt(s, r)) { | |
601 | while (p != s->mnt_parent) { | |
602 | p = p->mnt_parent; | |
603 | q = q->mnt_parent; | |
604 | } | |
605 | p = s; | |
606 | nd.mnt = q; | |
607 | nd.dentry = p->mnt_mountpoint; | |
36341f64 | 608 | q = clone_mnt(p, p->mnt_root, flag); |
1da177e4 LT |
609 | if (!q) |
610 | goto Enomem; | |
611 | spin_lock(&vfsmount_lock); | |
612 | list_add_tail(&q->mnt_list, &res->mnt_list); | |
613 | attach_mnt(q, &nd); | |
614 | spin_unlock(&vfsmount_lock); | |
615 | } | |
616 | } | |
617 | return res; | |
b58fed8b | 618 | Enomem: |
1da177e4 | 619 | if (res) { |
70fbcdf4 | 620 | LIST_HEAD(umount_list); |
1da177e4 | 621 | spin_lock(&vfsmount_lock); |
70fbcdf4 | 622 | umount_tree(res, &umount_list); |
1da177e4 | 623 | spin_unlock(&vfsmount_lock); |
70fbcdf4 | 624 | release_mounts(&umount_list); |
1da177e4 LT |
625 | } |
626 | return NULL; | |
627 | } | |
628 | ||
629 | static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) | |
630 | { | |
631 | int err; | |
632 | if (mnt->mnt_sb->s_flags & MS_NOUSER) | |
633 | return -EINVAL; | |
634 | ||
635 | if (S_ISDIR(nd->dentry->d_inode->i_mode) != | |
636 | S_ISDIR(mnt->mnt_root->d_inode->i_mode)) | |
637 | return -ENOTDIR; | |
638 | ||
639 | err = -ENOENT; | |
640 | down(&nd->dentry->d_inode->i_sem); | |
641 | if (IS_DEADDIR(nd->dentry->d_inode)) | |
642 | goto out_unlock; | |
643 | ||
644 | err = security_sb_check_sb(mnt, nd); | |
645 | if (err) | |
646 | goto out_unlock; | |
647 | ||
648 | err = -ENOENT; | |
649 | spin_lock(&vfsmount_lock); | |
650 | if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) { | |
651 | struct list_head head; | |
652 | ||
653 | attach_mnt(mnt, nd); | |
654 | list_add_tail(&head, &mnt->mnt_list); | |
655 | list_splice(&head, current->namespace->list.prev); | |
1da177e4 | 656 | err = 0; |
5addc5dd | 657 | touch_namespace(current->namespace); |
1da177e4 LT |
658 | } |
659 | spin_unlock(&vfsmount_lock); | |
660 | out_unlock: | |
661 | up(&nd->dentry->d_inode->i_sem); | |
662 | if (!err) | |
663 | security_sb_post_addmount(mnt, nd); | |
664 | return err; | |
665 | } | |
666 | ||
07b20889 RP |
667 | /* |
668 | * recursively change the type of the mountpoint. | |
669 | */ | |
670 | static int do_change_type(struct nameidata *nd, int flag) | |
671 | { | |
672 | struct vfsmount *m, *mnt = nd->mnt; | |
673 | int recurse = flag & MS_REC; | |
674 | int type = flag & ~MS_REC; | |
675 | ||
676 | if (nd->dentry != nd->mnt->mnt_root) | |
677 | return -EINVAL; | |
678 | ||
679 | down_write(&namespace_sem); | |
680 | spin_lock(&vfsmount_lock); | |
681 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) | |
682 | change_mnt_propagation(m, type); | |
683 | spin_unlock(&vfsmount_lock); | |
684 | up_write(&namespace_sem); | |
685 | return 0; | |
686 | } | |
687 | ||
1da177e4 LT |
688 | /* |
689 | * do loopback mount. | |
690 | */ | |
691 | static int do_loopback(struct nameidata *nd, char *old_name, int recurse) | |
692 | { | |
693 | struct nameidata old_nd; | |
694 | struct vfsmount *mnt = NULL; | |
695 | int err = mount_is_safe(nd); | |
696 | if (err) | |
697 | return err; | |
698 | if (!old_name || !*old_name) | |
699 | return -EINVAL; | |
700 | err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); | |
701 | if (err) | |
702 | return err; | |
703 | ||
390c6843 | 704 | down_write(&namespace_sem); |
1da177e4 | 705 | err = -EINVAL; |
ccd48bc7 AV |
706 | if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) |
707 | goto out; | |
1da177e4 | 708 | |
ccd48bc7 AV |
709 | err = -ENOMEM; |
710 | if (recurse) | |
36341f64 | 711 | mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0); |
ccd48bc7 | 712 | else |
36341f64 | 713 | mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0); |
ccd48bc7 AV |
714 | |
715 | if (!mnt) | |
716 | goto out; | |
717 | ||
ccd48bc7 AV |
718 | err = graft_tree(mnt, nd); |
719 | if (err) { | |
70fbcdf4 | 720 | LIST_HEAD(umount_list); |
1da177e4 | 721 | spin_lock(&vfsmount_lock); |
70fbcdf4 | 722 | umount_tree(mnt, &umount_list); |
1da177e4 | 723 | spin_unlock(&vfsmount_lock); |
70fbcdf4 | 724 | release_mounts(&umount_list); |
5b83d2c5 | 725 | } |
1da177e4 | 726 | |
ccd48bc7 | 727 | out: |
390c6843 | 728 | up_write(&namespace_sem); |
1da177e4 LT |
729 | path_release(&old_nd); |
730 | return err; | |
731 | } | |
732 | ||
733 | /* | |
734 | * change filesystem flags. dir should be a physical root of filesystem. | |
735 | * If you've mounted a non-root directory somewhere and want to do remount | |
736 | * on it - tough luck. | |
737 | */ | |
1da177e4 LT |
738 | static int do_remount(struct nameidata *nd, int flags, int mnt_flags, |
739 | void *data) | |
740 | { | |
741 | int err; | |
b58fed8b | 742 | struct super_block *sb = nd->mnt->mnt_sb; |
1da177e4 LT |
743 | |
744 | if (!capable(CAP_SYS_ADMIN)) | |
745 | return -EPERM; | |
746 | ||
747 | if (!check_mnt(nd->mnt)) | |
748 | return -EINVAL; | |
749 | ||
750 | if (nd->dentry != nd->mnt->mnt_root) | |
751 | return -EINVAL; | |
752 | ||
753 | down_write(&sb->s_umount); | |
754 | err = do_remount_sb(sb, flags, data, 0); | |
755 | if (!err) | |
b58fed8b | 756 | nd->mnt->mnt_flags = mnt_flags; |
1da177e4 LT |
757 | up_write(&sb->s_umount); |
758 | if (!err) | |
759 | security_sb_post_remount(nd->mnt, flags, data); | |
760 | return err; | |
761 | } | |
762 | ||
763 | static int do_move_mount(struct nameidata *nd, char *old_name) | |
764 | { | |
765 | struct nameidata old_nd, parent_nd; | |
766 | struct vfsmount *p; | |
767 | int err = 0; | |
768 | if (!capable(CAP_SYS_ADMIN)) | |
769 | return -EPERM; | |
770 | if (!old_name || !*old_name) | |
771 | return -EINVAL; | |
772 | err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); | |
773 | if (err) | |
774 | return err; | |
775 | ||
390c6843 | 776 | down_write(&namespace_sem); |
b58fed8b | 777 | while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
1da177e4 LT |
778 | ; |
779 | err = -EINVAL; | |
780 | if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) | |
781 | goto out; | |
782 | ||
783 | err = -ENOENT; | |
784 | down(&nd->dentry->d_inode->i_sem); | |
785 | if (IS_DEADDIR(nd->dentry->d_inode)) | |
786 | goto out1; | |
787 | ||
788 | spin_lock(&vfsmount_lock); | |
789 | if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) | |
790 | goto out2; | |
791 | ||
792 | err = -EINVAL; | |
793 | if (old_nd.dentry != old_nd.mnt->mnt_root) | |
794 | goto out2; | |
795 | ||
796 | if (old_nd.mnt == old_nd.mnt->mnt_parent) | |
797 | goto out2; | |
798 | ||
799 | if (S_ISDIR(nd->dentry->d_inode->i_mode) != | |
800 | S_ISDIR(old_nd.dentry->d_inode->i_mode)) | |
801 | goto out2; | |
802 | ||
803 | err = -ELOOP; | |
b58fed8b | 804 | for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent) |
1da177e4 LT |
805 | if (p == old_nd.mnt) |
806 | goto out2; | |
807 | err = 0; | |
808 | ||
809 | detach_mnt(old_nd.mnt, &parent_nd); | |
810 | attach_mnt(old_nd.mnt, nd); | |
5addc5dd | 811 | touch_namespace(current->namespace); |
1da177e4 LT |
812 | |
813 | /* if the mount is moved, it should no longer be expire | |
814 | * automatically */ | |
55e700b9 | 815 | list_del_init(&old_nd.mnt->mnt_expire); |
1da177e4 LT |
816 | out2: |
817 | spin_unlock(&vfsmount_lock); | |
818 | out1: | |
819 | up(&nd->dentry->d_inode->i_sem); | |
820 | out: | |
390c6843 | 821 | up_write(&namespace_sem); |
1da177e4 LT |
822 | if (!err) |
823 | path_release(&parent_nd); | |
824 | path_release(&old_nd); | |
825 | return err; | |
826 | } | |
827 | ||
828 | /* | |
829 | * create a new mount for userspace and request it to be added into the | |
830 | * namespace's tree | |
831 | */ | |
832 | static int do_new_mount(struct nameidata *nd, char *type, int flags, | |
833 | int mnt_flags, char *name, void *data) | |
834 | { | |
835 | struct vfsmount *mnt; | |
836 | ||
837 | if (!type || !memchr(type, 0, PAGE_SIZE)) | |
838 | return -EINVAL; | |
839 | ||
840 | /* we need capabilities... */ | |
841 | if (!capable(CAP_SYS_ADMIN)) | |
842 | return -EPERM; | |
843 | ||
844 | mnt = do_kern_mount(type, flags, name, data); | |
845 | if (IS_ERR(mnt)) | |
846 | return PTR_ERR(mnt); | |
847 | ||
848 | return do_add_mount(mnt, nd, mnt_flags, NULL); | |
849 | } | |
850 | ||
851 | /* | |
852 | * add a mount into a namespace's mount tree | |
853 | * - provide the option of adding the new mount to an expiration list | |
854 | */ | |
855 | int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, | |
856 | int mnt_flags, struct list_head *fslist) | |
857 | { | |
858 | int err; | |
859 | ||
390c6843 | 860 | down_write(&namespace_sem); |
1da177e4 | 861 | /* Something was mounted here while we slept */ |
b58fed8b | 862 | while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
1da177e4 LT |
863 | ; |
864 | err = -EINVAL; | |
865 | if (!check_mnt(nd->mnt)) | |
866 | goto unlock; | |
867 | ||
868 | /* Refuse the same filesystem on the same mount point */ | |
869 | err = -EBUSY; | |
870 | if (nd->mnt->mnt_sb == newmnt->mnt_sb && | |
871 | nd->mnt->mnt_root == nd->dentry) | |
872 | goto unlock; | |
873 | ||
874 | err = -EINVAL; | |
875 | if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) | |
876 | goto unlock; | |
877 | ||
878 | newmnt->mnt_flags = mnt_flags; | |
5b83d2c5 RP |
879 | if ((err = graft_tree(newmnt, nd))) |
880 | goto unlock; | |
1da177e4 | 881 | |
5b83d2c5 | 882 | if (fslist) { |
1da177e4 LT |
883 | /* add to the specified expiration list */ |
884 | spin_lock(&vfsmount_lock); | |
55e700b9 | 885 | list_add_tail(&newmnt->mnt_expire, fslist); |
1da177e4 LT |
886 | spin_unlock(&vfsmount_lock); |
887 | } | |
390c6843 | 888 | up_write(&namespace_sem); |
5b83d2c5 | 889 | return 0; |
1da177e4 LT |
890 | |
891 | unlock: | |
390c6843 | 892 | up_write(&namespace_sem); |
1da177e4 LT |
893 | mntput(newmnt); |
894 | return err; | |
895 | } | |
896 | ||
897 | EXPORT_SYMBOL_GPL(do_add_mount); | |
898 | ||
70fbcdf4 RP |
899 | static void expire_mount(struct vfsmount *mnt, struct list_head *mounts, |
900 | struct list_head *umounts) | |
24ca2af1 MS |
901 | { |
902 | spin_lock(&vfsmount_lock); | |
903 | ||
ed42c879 MS |
904 | /* |
905 | * Check if mount is still attached, if not, let whoever holds it deal | |
906 | * with the sucker | |
907 | */ | |
908 | if (mnt->mnt_parent == mnt) { | |
909 | spin_unlock(&vfsmount_lock); | |
910 | return; | |
911 | } | |
912 | ||
24ca2af1 MS |
913 | /* |
914 | * Check that it is still dead: the count should now be 2 - as | |
915 | * contributed by the vfsmount parent and the mntget above | |
916 | */ | |
917 | if (atomic_read(&mnt->mnt_count) == 2) { | |
24ca2af1 | 918 | /* delete from the namespace */ |
5addc5dd | 919 | touch_namespace(mnt->mnt_namespace); |
24ca2af1 | 920 | list_del_init(&mnt->mnt_list); |
ac081153 | 921 | mnt->mnt_namespace = NULL; |
70fbcdf4 | 922 | umount_tree(mnt, umounts); |
24ca2af1 | 923 | spin_unlock(&vfsmount_lock); |
24ca2af1 MS |
924 | } else { |
925 | /* | |
926 | * Someone brought it back to life whilst we didn't have any | |
927 | * locks held so return it to the expiration list | |
928 | */ | |
55e700b9 | 929 | list_add_tail(&mnt->mnt_expire, mounts); |
24ca2af1 MS |
930 | spin_unlock(&vfsmount_lock); |
931 | } | |
932 | } | |
933 | ||
1da177e4 LT |
934 | /* |
935 | * process a list of expirable mountpoints with the intent of discarding any | |
936 | * mountpoints that aren't in use and haven't been touched since last we came | |
937 | * here | |
938 | */ | |
939 | void mark_mounts_for_expiry(struct list_head *mounts) | |
940 | { | |
941 | struct namespace *namespace; | |
942 | struct vfsmount *mnt, *next; | |
943 | LIST_HEAD(graveyard); | |
944 | ||
945 | if (list_empty(mounts)) | |
946 | return; | |
947 | ||
948 | spin_lock(&vfsmount_lock); | |
949 | ||
950 | /* extract from the expiration list every vfsmount that matches the | |
951 | * following criteria: | |
952 | * - only referenced by its parent vfsmount | |
953 | * - still marked for expiry (marked on the last call here; marks are | |
954 | * cleared by mntput()) | |
955 | */ | |
55e700b9 | 956 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
1da177e4 LT |
957 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
958 | atomic_read(&mnt->mnt_count) != 1) | |
959 | continue; | |
960 | ||
961 | mntget(mnt); | |
55e700b9 | 962 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 LT |
963 | } |
964 | ||
965 | /* | |
966 | * go through the vfsmounts we've just consigned to the graveyard to | |
967 | * - check that they're still dead | |
968 | * - delete the vfsmount from the appropriate namespace under lock | |
969 | * - dispose of the corpse | |
970 | */ | |
971 | while (!list_empty(&graveyard)) { | |
70fbcdf4 | 972 | LIST_HEAD(umounts); |
55e700b9 MS |
973 | mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire); |
974 | list_del_init(&mnt->mnt_expire); | |
1da177e4 LT |
975 | |
976 | /* don't do anything if the namespace is dead - all the | |
977 | * vfsmounts from it are going away anyway */ | |
978 | namespace = mnt->mnt_namespace; | |
1ce88cf4 | 979 | if (!namespace || !namespace->root) |
1da177e4 LT |
980 | continue; |
981 | get_namespace(namespace); | |
982 | ||
983 | spin_unlock(&vfsmount_lock); | |
390c6843 | 984 | down_write(&namespace_sem); |
70fbcdf4 | 985 | expire_mount(mnt, mounts, &umounts); |
390c6843 | 986 | up_write(&namespace_sem); |
70fbcdf4 | 987 | release_mounts(&umounts); |
1da177e4 LT |
988 | mntput(mnt); |
989 | put_namespace(namespace); | |
1da177e4 LT |
990 | spin_lock(&vfsmount_lock); |
991 | } | |
992 | ||
993 | spin_unlock(&vfsmount_lock); | |
994 | } | |
995 | ||
996 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
997 | ||
998 | /* | |
999 | * Some copy_from_user() implementations do not return the exact number of | |
1000 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. | |
1001 | * Note that this function differs from copy_from_user() in that it will oops | |
1002 | * on bad values of `to', rather than returning a short copy. | |
1003 | */ | |
b58fed8b RP |
1004 | static long exact_copy_from_user(void *to, const void __user * from, |
1005 | unsigned long n) | |
1da177e4 LT |
1006 | { |
1007 | char *t = to; | |
1008 | const char __user *f = from; | |
1009 | char c; | |
1010 | ||
1011 | if (!access_ok(VERIFY_READ, from, n)) | |
1012 | return n; | |
1013 | ||
1014 | while (n) { | |
1015 | if (__get_user(c, f)) { | |
1016 | memset(t, 0, n); | |
1017 | break; | |
1018 | } | |
1019 | *t++ = c; | |
1020 | f++; | |
1021 | n--; | |
1022 | } | |
1023 | return n; | |
1024 | } | |
1025 | ||
b58fed8b | 1026 | int copy_mount_options(const void __user * data, unsigned long *where) |
1da177e4 LT |
1027 | { |
1028 | int i; | |
1029 | unsigned long page; | |
1030 | unsigned long size; | |
b58fed8b | 1031 | |
1da177e4 LT |
1032 | *where = 0; |
1033 | if (!data) | |
1034 | return 0; | |
1035 | ||
1036 | if (!(page = __get_free_page(GFP_KERNEL))) | |
1037 | return -ENOMEM; | |
1038 | ||
1039 | /* We only care that *some* data at the address the user | |
1040 | * gave us is valid. Just in case, we'll zero | |
1041 | * the remainder of the page. | |
1042 | */ | |
1043 | /* copy_from_user cannot cross TASK_SIZE ! */ | |
1044 | size = TASK_SIZE - (unsigned long)data; | |
1045 | if (size > PAGE_SIZE) | |
1046 | size = PAGE_SIZE; | |
1047 | ||
1048 | i = size - exact_copy_from_user((void *)page, data, size); | |
1049 | if (!i) { | |
b58fed8b | 1050 | free_page(page); |
1da177e4 LT |
1051 | return -EFAULT; |
1052 | } | |
1053 | if (i != PAGE_SIZE) | |
1054 | memset((char *)page + i, 0, PAGE_SIZE - i); | |
1055 | *where = page; | |
1056 | return 0; | |
1057 | } | |
1058 | ||
1059 | /* | |
1060 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
1061 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
1062 | * | |
1063 | * data is a (void *) that can point to any structure up to | |
1064 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
1065 | * information (or be NULL). | |
1066 | * | |
1067 | * Pre-0.97 versions of mount() didn't have a flags word. | |
1068 | * When the flags word was introduced its top half was required | |
1069 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
1070 | * Therefore, if this magic number is present, it carries no information | |
1071 | * and must be discarded. | |
1072 | */ | |
b58fed8b | 1073 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
1da177e4 LT |
1074 | unsigned long flags, void *data_page) |
1075 | { | |
1076 | struct nameidata nd; | |
1077 | int retval = 0; | |
1078 | int mnt_flags = 0; | |
1079 | ||
1080 | /* Discard magic */ | |
1081 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
1082 | flags &= ~MS_MGC_MSK; | |
1083 | ||
1084 | /* Basic sanity checks */ | |
1085 | ||
1086 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) | |
1087 | return -EINVAL; | |
1088 | if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) | |
1089 | return -EINVAL; | |
1090 | ||
1091 | if (data_page) | |
1092 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
1093 | ||
1094 | /* Separate the per-mountpoint flags */ | |
1095 | if (flags & MS_NOSUID) | |
1096 | mnt_flags |= MNT_NOSUID; | |
1097 | if (flags & MS_NODEV) | |
1098 | mnt_flags |= MNT_NODEV; | |
1099 | if (flags & MS_NOEXEC) | |
1100 | mnt_flags |= MNT_NOEXEC; | |
b58fed8b | 1101 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE); |
1da177e4 LT |
1102 | |
1103 | /* ... and get the mountpoint */ | |
1104 | retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); | |
1105 | if (retval) | |
1106 | return retval; | |
1107 | ||
1108 | retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page); | |
1109 | if (retval) | |
1110 | goto dput_out; | |
1111 | ||
1112 | if (flags & MS_REMOUNT) | |
1113 | retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, | |
1114 | data_page); | |
1115 | else if (flags & MS_BIND) | |
1116 | retval = do_loopback(&nd, dev_name, flags & MS_REC); | |
03e06e68 | 1117 | else if (flags & (MS_SHARED | MS_PRIVATE)) |
07b20889 | 1118 | retval = do_change_type(&nd, flags); |
1da177e4 LT |
1119 | else if (flags & MS_MOVE) |
1120 | retval = do_move_mount(&nd, dev_name); | |
1121 | else | |
1122 | retval = do_new_mount(&nd, type_page, flags, mnt_flags, | |
1123 | dev_name, data_page); | |
1124 | dput_out: | |
1125 | path_release(&nd); | |
1126 | return retval; | |
1127 | } | |
1128 | ||
1129 | int copy_namespace(int flags, struct task_struct *tsk) | |
1130 | { | |
1131 | struct namespace *namespace = tsk->namespace; | |
1132 | struct namespace *new_ns; | |
1133 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL; | |
1134 | struct fs_struct *fs = tsk->fs; | |
1135 | struct vfsmount *p, *q; | |
1136 | ||
1137 | if (!namespace) | |
1138 | return 0; | |
1139 | ||
1140 | get_namespace(namespace); | |
1141 | ||
1142 | if (!(flags & CLONE_NEWNS)) | |
1143 | return 0; | |
1144 | ||
1145 | if (!capable(CAP_SYS_ADMIN)) { | |
1146 | put_namespace(namespace); | |
1147 | return -EPERM; | |
1148 | } | |
1149 | ||
1150 | new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL); | |
1151 | if (!new_ns) | |
1152 | goto out; | |
1153 | ||
1154 | atomic_set(&new_ns->count, 1); | |
1da177e4 | 1155 | INIT_LIST_HEAD(&new_ns->list); |
5addc5dd AV |
1156 | init_waitqueue_head(&new_ns->poll); |
1157 | new_ns->event = 0; | |
1da177e4 | 1158 | |
390c6843 | 1159 | down_write(&namespace_sem); |
1da177e4 | 1160 | /* First pass: copy the tree topology */ |
36341f64 RP |
1161 | new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root, |
1162 | CL_EXPIRE); | |
1da177e4 | 1163 | if (!new_ns->root) { |
390c6843 | 1164 | up_write(&namespace_sem); |
1da177e4 LT |
1165 | kfree(new_ns); |
1166 | goto out; | |
1167 | } | |
1168 | spin_lock(&vfsmount_lock); | |
1169 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); | |
1170 | spin_unlock(&vfsmount_lock); | |
1171 | ||
1172 | /* | |
1173 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
1174 | * as belonging to new namespace. We have already acquired a private | |
1175 | * fs_struct, so tsk->fs->lock is not needed. | |
1176 | */ | |
1177 | p = namespace->root; | |
1178 | q = new_ns->root; | |
1179 | while (p) { | |
1180 | q->mnt_namespace = new_ns; | |
1181 | if (fs) { | |
1182 | if (p == fs->rootmnt) { | |
1183 | rootmnt = p; | |
1184 | fs->rootmnt = mntget(q); | |
1185 | } | |
1186 | if (p == fs->pwdmnt) { | |
1187 | pwdmnt = p; | |
1188 | fs->pwdmnt = mntget(q); | |
1189 | } | |
1190 | if (p == fs->altrootmnt) { | |
1191 | altrootmnt = p; | |
1192 | fs->altrootmnt = mntget(q); | |
1193 | } | |
1194 | } | |
1195 | p = next_mnt(p, namespace->root); | |
1196 | q = next_mnt(q, new_ns->root); | |
1197 | } | |
390c6843 | 1198 | up_write(&namespace_sem); |
1da177e4 LT |
1199 | |
1200 | tsk->namespace = new_ns; | |
1201 | ||
1202 | if (rootmnt) | |
1203 | mntput(rootmnt); | |
1204 | if (pwdmnt) | |
1205 | mntput(pwdmnt); | |
1206 | if (altrootmnt) | |
1207 | mntput(altrootmnt); | |
1208 | ||
1209 | put_namespace(namespace); | |
1210 | return 0; | |
1211 | ||
1212 | out: | |
1213 | put_namespace(namespace); | |
1214 | return -ENOMEM; | |
1215 | } | |
1216 | ||
1217 | asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name, | |
1218 | char __user * type, unsigned long flags, | |
1219 | void __user * data) | |
1220 | { | |
1221 | int retval; | |
1222 | unsigned long data_page; | |
1223 | unsigned long type_page; | |
1224 | unsigned long dev_page; | |
1225 | char *dir_page; | |
1226 | ||
b58fed8b | 1227 | retval = copy_mount_options(type, &type_page); |
1da177e4 LT |
1228 | if (retval < 0) |
1229 | return retval; | |
1230 | ||
1231 | dir_page = getname(dir_name); | |
1232 | retval = PTR_ERR(dir_page); | |
1233 | if (IS_ERR(dir_page)) | |
1234 | goto out1; | |
1235 | ||
b58fed8b | 1236 | retval = copy_mount_options(dev_name, &dev_page); |
1da177e4 LT |
1237 | if (retval < 0) |
1238 | goto out2; | |
1239 | ||
b58fed8b | 1240 | retval = copy_mount_options(data, &data_page); |
1da177e4 LT |
1241 | if (retval < 0) |
1242 | goto out3; | |
1243 | ||
1244 | lock_kernel(); | |
b58fed8b RP |
1245 | retval = do_mount((char *)dev_page, dir_page, (char *)type_page, |
1246 | flags, (void *)data_page); | |
1da177e4 LT |
1247 | unlock_kernel(); |
1248 | free_page(data_page); | |
1249 | ||
1250 | out3: | |
1251 | free_page(dev_page); | |
1252 | out2: | |
1253 | putname(dir_page); | |
1254 | out1: | |
1255 | free_page(type_page); | |
1256 | return retval; | |
1257 | } | |
1258 | ||
1259 | /* | |
1260 | * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. | |
1261 | * It can block. Requires the big lock held. | |
1262 | */ | |
1263 | void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt, | |
1264 | struct dentry *dentry) | |
1265 | { | |
1266 | struct dentry *old_root; | |
1267 | struct vfsmount *old_rootmnt; | |
1268 | write_lock(&fs->lock); | |
1269 | old_root = fs->root; | |
1270 | old_rootmnt = fs->rootmnt; | |
1271 | fs->rootmnt = mntget(mnt); | |
1272 | fs->root = dget(dentry); | |
1273 | write_unlock(&fs->lock); | |
1274 | if (old_root) { | |
1275 | dput(old_root); | |
1276 | mntput(old_rootmnt); | |
1277 | } | |
1278 | } | |
1279 | ||
1280 | /* | |
1281 | * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. | |
1282 | * It can block. Requires the big lock held. | |
1283 | */ | |
1284 | void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, | |
1285 | struct dentry *dentry) | |
1286 | { | |
1287 | struct dentry *old_pwd; | |
1288 | struct vfsmount *old_pwdmnt; | |
1289 | ||
1290 | write_lock(&fs->lock); | |
1291 | old_pwd = fs->pwd; | |
1292 | old_pwdmnt = fs->pwdmnt; | |
1293 | fs->pwdmnt = mntget(mnt); | |
1294 | fs->pwd = dget(dentry); | |
1295 | write_unlock(&fs->lock); | |
1296 | ||
1297 | if (old_pwd) { | |
1298 | dput(old_pwd); | |
1299 | mntput(old_pwdmnt); | |
1300 | } | |
1301 | } | |
1302 | ||
1303 | static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) | |
1304 | { | |
1305 | struct task_struct *g, *p; | |
1306 | struct fs_struct *fs; | |
1307 | ||
1308 | read_lock(&tasklist_lock); | |
1309 | do_each_thread(g, p) { | |
1310 | task_lock(p); | |
1311 | fs = p->fs; | |
1312 | if (fs) { | |
1313 | atomic_inc(&fs->count); | |
1314 | task_unlock(p); | |
b58fed8b RP |
1315 | if (fs->root == old_nd->dentry |
1316 | && fs->rootmnt == old_nd->mnt) | |
1da177e4 | 1317 | set_fs_root(fs, new_nd->mnt, new_nd->dentry); |
b58fed8b RP |
1318 | if (fs->pwd == old_nd->dentry |
1319 | && fs->pwdmnt == old_nd->mnt) | |
1da177e4 LT |
1320 | set_fs_pwd(fs, new_nd->mnt, new_nd->dentry); |
1321 | put_fs_struct(fs); | |
1322 | } else | |
1323 | task_unlock(p); | |
1324 | } while_each_thread(g, p); | |
1325 | read_unlock(&tasklist_lock); | |
1326 | } | |
1327 | ||
1328 | /* | |
1329 | * pivot_root Semantics: | |
1330 | * Moves the root file system of the current process to the directory put_old, | |
1331 | * makes new_root as the new root file system of the current process, and sets | |
1332 | * root/cwd of all processes which had them on the current root to new_root. | |
1333 | * | |
1334 | * Restrictions: | |
1335 | * The new_root and put_old must be directories, and must not be on the | |
1336 | * same file system as the current process root. The put_old must be | |
1337 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
1338 | * pointed to by put_old must yield the same directory as new_root. No other | |
1339 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
1340 | * | |
1341 | * Notes: | |
1342 | * - we don't move root/cwd if they are not at the root (reason: if something | |
1343 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
1344 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
1345 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
1346 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
1347 | * first. | |
1348 | */ | |
b58fed8b RP |
1349 | asmlinkage long sys_pivot_root(const char __user * new_root, |
1350 | const char __user * put_old) | |
1da177e4 LT |
1351 | { |
1352 | struct vfsmount *tmp; | |
1353 | struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; | |
1354 | int error; | |
1355 | ||
1356 | if (!capable(CAP_SYS_ADMIN)) | |
1357 | return -EPERM; | |
1358 | ||
1359 | lock_kernel(); | |
1360 | ||
b58fed8b RP |
1361 | error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, |
1362 | &new_nd); | |
1da177e4 LT |
1363 | if (error) |
1364 | goto out0; | |
1365 | error = -EINVAL; | |
1366 | if (!check_mnt(new_nd.mnt)) | |
1367 | goto out1; | |
1368 | ||
b58fed8b | 1369 | error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd); |
1da177e4 LT |
1370 | if (error) |
1371 | goto out1; | |
1372 | ||
1373 | error = security_sb_pivotroot(&old_nd, &new_nd); | |
1374 | if (error) { | |
1375 | path_release(&old_nd); | |
1376 | goto out1; | |
1377 | } | |
1378 | ||
1379 | read_lock(¤t->fs->lock); | |
1380 | user_nd.mnt = mntget(current->fs->rootmnt); | |
1381 | user_nd.dentry = dget(current->fs->root); | |
1382 | read_unlock(¤t->fs->lock); | |
390c6843 | 1383 | down_write(&namespace_sem); |
1da177e4 LT |
1384 | down(&old_nd.dentry->d_inode->i_sem); |
1385 | error = -EINVAL; | |
1386 | if (!check_mnt(user_nd.mnt)) | |
1387 | goto out2; | |
1388 | error = -ENOENT; | |
1389 | if (IS_DEADDIR(new_nd.dentry->d_inode)) | |
1390 | goto out2; | |
1391 | if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry)) | |
1392 | goto out2; | |
1393 | if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry)) | |
1394 | goto out2; | |
1395 | error = -EBUSY; | |
1396 | if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt) | |
1397 | goto out2; /* loop, on the same file system */ | |
1398 | error = -EINVAL; | |
1399 | if (user_nd.mnt->mnt_root != user_nd.dentry) | |
1400 | goto out2; /* not a mountpoint */ | |
0bb6fcc1 MS |
1401 | if (user_nd.mnt->mnt_parent == user_nd.mnt) |
1402 | goto out2; /* not attached */ | |
1da177e4 LT |
1403 | if (new_nd.mnt->mnt_root != new_nd.dentry) |
1404 | goto out2; /* not a mountpoint */ | |
0bb6fcc1 MS |
1405 | if (new_nd.mnt->mnt_parent == new_nd.mnt) |
1406 | goto out2; /* not attached */ | |
1da177e4 LT |
1407 | tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */ |
1408 | spin_lock(&vfsmount_lock); | |
1409 | if (tmp != new_nd.mnt) { | |
1410 | for (;;) { | |
1411 | if (tmp->mnt_parent == tmp) | |
1412 | goto out3; /* already mounted on put_old */ | |
1413 | if (tmp->mnt_parent == new_nd.mnt) | |
1414 | break; | |
1415 | tmp = tmp->mnt_parent; | |
1416 | } | |
1417 | if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry)) | |
1418 | goto out3; | |
1419 | } else if (!is_subdir(old_nd.dentry, new_nd.dentry)) | |
1420 | goto out3; | |
1421 | detach_mnt(new_nd.mnt, &parent_nd); | |
1422 | detach_mnt(user_nd.mnt, &root_parent); | |
1423 | attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ | |
1424 | attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ | |
5addc5dd | 1425 | touch_namespace(current->namespace); |
1da177e4 LT |
1426 | spin_unlock(&vfsmount_lock); |
1427 | chroot_fs_refs(&user_nd, &new_nd); | |
1428 | security_sb_post_pivotroot(&user_nd, &new_nd); | |
1429 | error = 0; | |
1430 | path_release(&root_parent); | |
1431 | path_release(&parent_nd); | |
1432 | out2: | |
1433 | up(&old_nd.dentry->d_inode->i_sem); | |
390c6843 | 1434 | up_write(&namespace_sem); |
1da177e4 LT |
1435 | path_release(&user_nd); |
1436 | path_release(&old_nd); | |
1437 | out1: | |
1438 | path_release(&new_nd); | |
1439 | out0: | |
1440 | unlock_kernel(); | |
1441 | return error; | |
1442 | out3: | |
1443 | spin_unlock(&vfsmount_lock); | |
1444 | goto out2; | |
1445 | } | |
1446 | ||
1447 | static void __init init_mount_tree(void) | |
1448 | { | |
1449 | struct vfsmount *mnt; | |
1450 | struct namespace *namespace; | |
1451 | struct task_struct *g, *p; | |
1452 | ||
1453 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); | |
1454 | if (IS_ERR(mnt)) | |
1455 | panic("Can't create rootfs"); | |
1456 | namespace = kmalloc(sizeof(*namespace), GFP_KERNEL); | |
1457 | if (!namespace) | |
1458 | panic("Can't allocate initial namespace"); | |
1459 | atomic_set(&namespace->count, 1); | |
1460 | INIT_LIST_HEAD(&namespace->list); | |
5addc5dd AV |
1461 | init_waitqueue_head(&namespace->poll); |
1462 | namespace->event = 0; | |
1da177e4 LT |
1463 | list_add(&mnt->mnt_list, &namespace->list); |
1464 | namespace->root = mnt; | |
1465 | mnt->mnt_namespace = namespace; | |
1466 | ||
1467 | init_task.namespace = namespace; | |
1468 | read_lock(&tasklist_lock); | |
1469 | do_each_thread(g, p) { | |
1470 | get_namespace(namespace); | |
1471 | p->namespace = namespace; | |
1472 | } while_each_thread(g, p); | |
1473 | read_unlock(&tasklist_lock); | |
1474 | ||
1475 | set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root); | |
1476 | set_fs_root(current->fs, namespace->root, namespace->root->mnt_root); | |
1477 | } | |
1478 | ||
1479 | void __init mnt_init(unsigned long mempages) | |
1480 | { | |
1481 | struct list_head *d; | |
1482 | unsigned int nr_hash; | |
1483 | int i; | |
1484 | ||
390c6843 RP |
1485 | init_rwsem(&namespace_sem); |
1486 | ||
1da177e4 | 1487 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), |
b58fed8b | 1488 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL, NULL); |
1da177e4 | 1489 | |
b58fed8b | 1490 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
1da177e4 LT |
1491 | |
1492 | if (!mount_hashtable) | |
1493 | panic("Failed to allocate mount hash table\n"); | |
1494 | ||
1495 | /* | |
1496 | * Find the power-of-two list-heads that can fit into the allocation.. | |
1497 | * We don't guarantee that "sizeof(struct list_head)" is necessarily | |
1498 | * a power-of-two. | |
1499 | */ | |
1500 | nr_hash = PAGE_SIZE / sizeof(struct list_head); | |
1501 | hash_bits = 0; | |
1502 | do { | |
1503 | hash_bits++; | |
1504 | } while ((nr_hash >> hash_bits) != 0); | |
1505 | hash_bits--; | |
1506 | ||
1507 | /* | |
1508 | * Re-calculate the actual number of entries and the mask | |
1509 | * from the number of bits we can fit. | |
1510 | */ | |
1511 | nr_hash = 1UL << hash_bits; | |
b58fed8b | 1512 | hash_mask = nr_hash - 1; |
1da177e4 LT |
1513 | |
1514 | printk("Mount-cache hash table entries: %d\n", nr_hash); | |
1515 | ||
1516 | /* And initialize the newly allocated array */ | |
1517 | d = mount_hashtable; | |
1518 | i = nr_hash; | |
1519 | do { | |
1520 | INIT_LIST_HEAD(d); | |
1521 | d++; | |
1522 | i--; | |
1523 | } while (i); | |
1524 | sysfs_init(); | |
1525 | init_rootfs(); | |
1526 | init_mount_tree(); | |
1527 | } | |
1528 | ||
1529 | void __put_namespace(struct namespace *namespace) | |
1530 | { | |
1ce88cf4 | 1531 | struct vfsmount *root = namespace->root; |
70fbcdf4 | 1532 | LIST_HEAD(umount_list); |
1ce88cf4 MS |
1533 | namespace->root = NULL; |
1534 | spin_unlock(&vfsmount_lock); | |
390c6843 | 1535 | down_write(&namespace_sem); |
1da177e4 | 1536 | spin_lock(&vfsmount_lock); |
70fbcdf4 | 1537 | umount_tree(root, &umount_list); |
1da177e4 | 1538 | spin_unlock(&vfsmount_lock); |
390c6843 | 1539 | up_write(&namespace_sem); |
70fbcdf4 | 1540 | release_mounts(&umount_list); |
1da177e4 LT |
1541 | kfree(namespace); |
1542 | } |