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