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rbtree: fix incorrect rbtree node insertion in fs/proc/proc_sysctl.c
[linux-2.6.git] / fs / proc / proc_sysctl.c
bloba781bdf0669464ced3e213faad5ed6ab3a37a06b
1 /*
2 * /proc/sys support
3 */
4 #include <linux/init.h>
5 #include <linux/sysctl.h>
6 #include <linux/poll.h>
7 #include <linux/proc_fs.h>
8 #include <linux/security.h>
9 #include <linux/sched.h>
10 #include <linux/namei.h>
11 #include <linux/mm.h>
12 #include <linux/module.h>
13 #include "internal.h"
14
15 static const struct dentry_operations proc_sys_dentry_operations;
16 static const struct file_operations proc_sys_file_operations;
17 static const struct inode_operations proc_sys_inode_operations;
18 static const struct file_operations proc_sys_dir_file_operations;
19 static const struct inode_operations proc_sys_dir_operations;
20
21 void proc_sys_poll_notify(struct ctl_table_poll *poll)
22 {
23 if (!poll)
24 return;
25
26 atomic_inc(&poll->event);
27 wake_up_interruptible(&poll->wait);
28 }
29
30 static struct ctl_table root_table[] = {
31 {
32 .procname = "",
33 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
34 },
35 { }
36 };
37 static struct ctl_table_root sysctl_table_root = {
38 .default_set.dir.header = {
39 {{.count = 1,
40 .nreg = 1,
41 .ctl_table = root_table }},
42 .ctl_table_arg = root_table,
43 .root = &sysctl_table_root,
44 .set = &sysctl_table_root.default_set,
45 },
46 };
47
48 static DEFINE_SPINLOCK(sysctl_lock);
49
50 static void drop_sysctl_table(struct ctl_table_header *header);
51 static int sysctl_follow_link(struct ctl_table_header **phead,
52 struct ctl_table **pentry, struct nsproxy *namespaces);
53 static int insert_links(struct ctl_table_header *head);
54 static void put_links(struct ctl_table_header *header);
55
56 static void sysctl_print_dir(struct ctl_dir *dir)
57 {
58 if (dir->header.parent)
59 sysctl_print_dir(dir->header.parent);
60 printk(KERN_CONT "%s/", dir->header.ctl_table[0].procname);
61 }
62
63 static int namecmp(const char *name1, int len1, const char *name2, int len2)
64 {
65 int minlen;
66 int cmp;
67
68 minlen = len1;
69 if (minlen > len2)
70 minlen = len2;
71
72 cmp = memcmp(name1, name2, minlen);
73 if (cmp == 0)
74 cmp = len1 - len2;
75 return cmp;
76 }
77
78 /* Called under sysctl_lock */
79 static struct ctl_table *find_entry(struct ctl_table_header **phead,
80 struct ctl_dir *dir, const char *name, int namelen)
81 {
82 struct ctl_table_header *head;
83 struct ctl_table *entry;
84 struct rb_node *node = dir->root.rb_node;
85
86 while (node)
87 {
88 struct ctl_node *ctl_node;
89 const char *procname;
90 int cmp;
91
92 ctl_node = rb_entry(node, struct ctl_node, node);
93 head = ctl_node->header;
94 entry = &head->ctl_table[ctl_node - head->node];
95 procname = entry->procname;
96
97 cmp = namecmp(name, namelen, procname, strlen(procname));
98 if (cmp < 0)
99 node = node->rb_left;
100 else if (cmp > 0)
101 node = node->rb_right;
102 else {
103 *phead = head;
104 return entry;
105 }
106 }
107 return NULL;
108 }
109
110 static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
111 {
112 struct rb_node *node = &head->node[entry - head->ctl_table].node;
113 struct rb_node **p = &head->parent->root.rb_node;
114 struct rb_node *parent = NULL;
115 const char *name = entry->procname;
116 int namelen = strlen(name);
117
118 while (*p) {
119 struct ctl_table_header *parent_head;
120 struct ctl_table *parent_entry;
121 struct ctl_node *parent_node;
122 const char *parent_name;
123 int cmp;
124
125 parent = *p;
126 parent_node = rb_entry(parent, struct ctl_node, node);
127 parent_head = parent_node->header;
128 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
129 parent_name = parent_entry->procname;
130
131 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
132 if (cmp < 0)
133 p = &(*p)->rb_left;
134 else if (cmp > 0)
135 p = &(*p)->rb_right;
136 else {
137 printk(KERN_ERR "sysctl duplicate entry: ");
138 sysctl_print_dir(head->parent);
139 printk(KERN_CONT "/%s\n", entry->procname);
140 return -EEXIST;
141 }
142 }
143
144 rb_link_node(node, parent, p);
145 rb_insert_color(node, &head->parent->root);
146 return 0;
147 }
148
149 static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
150 {
151 struct rb_node *node = &head->node[entry - head->ctl_table].node;
152
153 rb_erase(node, &head->parent->root);
154 }
155
156 static void init_header(struct ctl_table_header *head,
157 struct ctl_table_root *root, struct ctl_table_set *set,
158 struct ctl_node *node, struct ctl_table *table)
159 {
160 head->ctl_table = table;
161 head->ctl_table_arg = table;
162 head->used = 0;
163 head->count = 1;
164 head->nreg = 1;
165 head->unregistering = NULL;
166 head->root = root;
167 head->set = set;
168 head->parent = NULL;
169 head->node = node;
170 if (node) {
171 struct ctl_table *entry;
172 for (entry = table; entry->procname; entry++, node++)
173 node->header = head;
174 }
175 }
176
177 static void erase_header(struct ctl_table_header *head)
178 {
179 struct ctl_table *entry;
180 for (entry = head->ctl_table; entry->procname; entry++)
181 erase_entry(head, entry);
182 }
183
184 static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
185 {
186 struct ctl_table *entry;
187 int err;
188
189 dir->header.nreg++;
190 header->parent = dir;
191 err = insert_links(header);
192 if (err)
193 goto fail_links;
194 for (entry = header->ctl_table; entry->procname; entry++) {
195 err = insert_entry(header, entry);
196 if (err)
197 goto fail;
198 }
199 return 0;
200 fail:
201 erase_header(header);
202 put_links(header);
203 fail_links:
204 header->parent = NULL;
205 drop_sysctl_table(&dir->header);
206 return err;
207 }
208
209 /* called under sysctl_lock */
210 static int use_table(struct ctl_table_header *p)
211 {
212 if (unlikely(p->unregistering))
213 return 0;
214 p->used++;
215 return 1;
216 }
217
218 /* called under sysctl_lock */
219 static void unuse_table(struct ctl_table_header *p)
220 {
221 if (!--p->used)
222 if (unlikely(p->unregistering))
223 complete(p->unregistering);
224 }
225
226 /* called under sysctl_lock, will reacquire if has to wait */
227 static void start_unregistering(struct ctl_table_header *p)
228 {
229 /*
230 * if p->used is 0, nobody will ever touch that entry again;
231 * we'll eliminate all paths to it before dropping sysctl_lock
232 */
233 if (unlikely(p->used)) {
234 struct completion wait;
235 init_completion(&wait);
236 p->unregistering = &wait;
237 spin_unlock(&sysctl_lock);
238 wait_for_completion(&wait);
239 spin_lock(&sysctl_lock);
240 } else {
241 /* anything non-NULL; we'll never dereference it */
242 p->unregistering = ERR_PTR(-EINVAL);
243 }
244 /*
245 * do not remove from the list until nobody holds it; walking the
246 * list in do_sysctl() relies on that.
247 */
248 erase_header(p);
249 }
250
251 static void sysctl_head_get(struct ctl_table_header *head)
252 {
253 spin_lock(&sysctl_lock);
254 head->count++;
255 spin_unlock(&sysctl_lock);
256 }
257
258 void sysctl_head_put(struct ctl_table_header *head)
259 {
260 spin_lock(&sysctl_lock);
261 if (!--head->count)
262 kfree_rcu(head, rcu);
263 spin_unlock(&sysctl_lock);
264 }
265
266 static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
267 {
268 BUG_ON(!head);
269 spin_lock(&sysctl_lock);
270 if (!use_table(head))
271 head = ERR_PTR(-ENOENT);
272 spin_unlock(&sysctl_lock);
273 return head;
274 }
275
276 static void sysctl_head_finish(struct ctl_table_header *head)
277 {
278 if (!head)
279 return;
280 spin_lock(&sysctl_lock);
281 unuse_table(head);
282 spin_unlock(&sysctl_lock);
283 }
284
285 static struct ctl_table_set *
286 lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces)
287 {
288 struct ctl_table_set *set = &root->default_set;
289 if (root->lookup)
290 set = root->lookup(root, namespaces);
291 return set;
292 }
293
294 static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
295 struct ctl_dir *dir,
296 const char *name, int namelen)
297 {
298 struct ctl_table_header *head;
299 struct ctl_table *entry;
300
301 spin_lock(&sysctl_lock);
302 entry = find_entry(&head, dir, name, namelen);
303 if (entry && use_table(head))
304 *phead = head;
305 else
306 entry = NULL;
307 spin_unlock(&sysctl_lock);
308 return entry;
309 }
310
311 static struct ctl_node *first_usable_entry(struct rb_node *node)
312 {
313 struct ctl_node *ctl_node;
314
315 for (;node; node = rb_next(node)) {
316 ctl_node = rb_entry(node, struct ctl_node, node);
317 if (use_table(ctl_node->header))
318 return ctl_node;
319 }
320 return NULL;
321 }
322
323 static void first_entry(struct ctl_dir *dir,
324 struct ctl_table_header **phead, struct ctl_table **pentry)
325 {
326 struct ctl_table_header *head = NULL;
327 struct ctl_table *entry = NULL;
328 struct ctl_node *ctl_node;
329
330 spin_lock(&sysctl_lock);
331 ctl_node = first_usable_entry(rb_first(&dir->root));
332 spin_unlock(&sysctl_lock);
333 if (ctl_node) {
334 head = ctl_node->header;
335 entry = &head->ctl_table[ctl_node - head->node];
336 }
337 *phead = head;
338 *pentry = entry;
339 }
340
341 static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
342 {
343 struct ctl_table_header *head = *phead;
344 struct ctl_table *entry = *pentry;
345 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
346
347 spin_lock(&sysctl_lock);
348 unuse_table(head);
349
350 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
351 spin_unlock(&sysctl_lock);
352 head = NULL;
353 if (ctl_node) {
354 head = ctl_node->header;
355 entry = &head->ctl_table[ctl_node - head->node];
356 }
357 *phead = head;
358 *pentry = entry;
359 }
360
361 void register_sysctl_root(struct ctl_table_root *root)
362 {
363 }
364
365 /*
366 * sysctl_perm does NOT grant the superuser all rights automatically, because
367 * some sysctl variables are readonly even to root.
368 */
369
370 static int test_perm(int mode, int op)
371 {
372 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
373 mode >>= 6;
374 else if (in_egroup_p(GLOBAL_ROOT_GID))
375 mode >>= 3;
376 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
377 return 0;
378 return -EACCES;
379 }
380
381 static int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op)
382 {
383 int mode;
384
385 if (root->permissions)
386 mode = root->permissions(root, current->nsproxy, table);
387 else
388 mode = table->mode;
389
390 return test_perm(mode, op);
391 }
392
393 static struct inode *proc_sys_make_inode(struct super_block *sb,
394 struct ctl_table_header *head, struct ctl_table *table)
395 {
396 struct inode *inode;
397 struct proc_inode *ei;
398
399 inode = new_inode(sb);
400 if (!inode)
401 goto out;
402
403 inode->i_ino = get_next_ino();
404
405 sysctl_head_get(head);
406 ei = PROC_I(inode);
407 ei->sysctl = head;
408 ei->sysctl_entry = table;
409
410 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
411 inode->i_mode = table->mode;
412 if (!S_ISDIR(table->mode)) {
413 inode->i_mode |= S_IFREG;
414 inode->i_op = &proc_sys_inode_operations;
415 inode->i_fop = &proc_sys_file_operations;
416 } else {
417 inode->i_mode |= S_IFDIR;
418 inode->i_op = &proc_sys_dir_operations;
419 inode->i_fop = &proc_sys_dir_file_operations;
420 }
421 out:
422 return inode;
423 }
424
425 static struct ctl_table_header *grab_header(struct inode *inode)
426 {
427 struct ctl_table_header *head = PROC_I(inode)->sysctl;
428 if (!head)
429 head = &sysctl_table_root.default_set.dir.header;
430 return sysctl_head_grab(head);
431 }
432
433 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
434 unsigned int flags)
435 {
436 struct ctl_table_header *head = grab_header(dir);
437 struct ctl_table_header *h = NULL;
438 struct qstr *name = &dentry->d_name;
439 struct ctl_table *p;
440 struct inode *inode;
441 struct dentry *err = ERR_PTR(-ENOENT);
442 struct ctl_dir *ctl_dir;
443 int ret;
444
445 if (IS_ERR(head))
446 return ERR_CAST(head);
447
448 ctl_dir = container_of(head, struct ctl_dir, header);
449
450 p = lookup_entry(&h, ctl_dir, name->name, name->len);
451 if (!p)
452 goto out;
453
454 if (S_ISLNK(p->mode)) {
455 ret = sysctl_follow_link(&h, &p, current->nsproxy);
456 err = ERR_PTR(ret);
457 if (ret)
458 goto out;
459 }
460
461 err = ERR_PTR(-ENOMEM);
462 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
463 if (!inode)
464 goto out;
465
466 err = NULL;
467 d_set_d_op(dentry, &proc_sys_dentry_operations);
468 d_add(dentry, inode);
469
470 out:
471 if (h)
472 sysctl_head_finish(h);
473 sysctl_head_finish(head);
474 return err;
475 }
476
477 static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
478 size_t count, loff_t *ppos, int write)
479 {
480 struct inode *inode = filp->f_path.dentry->d_inode;
481 struct ctl_table_header *head = grab_header(inode);
482 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
483 ssize_t error;
484 size_t res;
485
486 if (IS_ERR(head))
487 return PTR_ERR(head);
488
489 /*
490 * At this point we know that the sysctl was not unregistered
491 * and won't be until we finish.
492 */
493 error = -EPERM;
494 if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
495 goto out;
496
497 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
498 error = -EINVAL;
499 if (!table->proc_handler)
500 goto out;
501
502 /* careful: calling conventions are nasty here */
503 res = count;
504 error = table->proc_handler(table, write, buf, &res, ppos);
505 if (!error)
506 error = res;
507 out:
508 sysctl_head_finish(head);
509
510 return error;
511 }
512
513 static ssize_t proc_sys_read(struct file *filp, char __user *buf,
514 size_t count, loff_t *ppos)
515 {
516 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
517 }
518
519 static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
520 size_t count, loff_t *ppos)
521 {
522 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
523 }
524
525 static int proc_sys_open(struct inode *inode, struct file *filp)
526 {
527 struct ctl_table_header *head = grab_header(inode);
528 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
529
530 /* sysctl was unregistered */
531 if (IS_ERR(head))
532 return PTR_ERR(head);
533
534 if (table->poll)
535 filp->private_data = proc_sys_poll_event(table->poll);
536
537 sysctl_head_finish(head);
538
539 return 0;
540 }
541
542 static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
543 {
544 struct inode *inode = filp->f_path.dentry->d_inode;
545 struct ctl_table_header *head = grab_header(inode);
546 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
547 unsigned int ret = DEFAULT_POLLMASK;
548 unsigned long event;
549
550 /* sysctl was unregistered */
551 if (IS_ERR(head))
552 return POLLERR | POLLHUP;
553
554 if (!table->proc_handler)
555 goto out;
556
557 if (!table->poll)
558 goto out;
559
560 event = (unsigned long)filp->private_data;
561 poll_wait(filp, &table->poll->wait, wait);
562
563 if (event != atomic_read(&table->poll->event)) {
564 filp->private_data = proc_sys_poll_event(table->poll);
565 ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI;
566 }
567
568 out:
569 sysctl_head_finish(head);
570
571 return ret;
572 }
573
574 static int proc_sys_fill_cache(struct file *filp, void *dirent,
575 filldir_t filldir,
576 struct ctl_table_header *head,
577 struct ctl_table *table)
578 {
579 struct dentry *child, *dir = filp->f_path.dentry;
580 struct inode *inode;
581 struct qstr qname;
582 ino_t ino = 0;
583 unsigned type = DT_UNKNOWN;
584
585 qname.name = table->procname;
586 qname.len = strlen(table->procname);
587 qname.hash = full_name_hash(qname.name, qname.len);
588
589 child = d_lookup(dir, &qname);
590 if (!child) {
591 child = d_alloc(dir, &qname);
592 if (child) {
593 inode = proc_sys_make_inode(dir->d_sb, head, table);
594 if (!inode) {
595 dput(child);
596 return -ENOMEM;
597 } else {
598 d_set_d_op(child, &proc_sys_dentry_operations);
599 d_add(child, inode);
600 }
601 } else {
602 return -ENOMEM;
603 }
604 }
605 inode = child->d_inode;
606 ino = inode->i_ino;
607 type = inode->i_mode >> 12;
608 dput(child);
609 return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
610 }
611
612 static int proc_sys_link_fill_cache(struct file *filp, void *dirent,
613 filldir_t filldir,
614 struct ctl_table_header *head,
615 struct ctl_table *table)
616 {
617 int err, ret = 0;
618 head = sysctl_head_grab(head);
619
620 if (S_ISLNK(table->mode)) {
621 /* It is not an error if we can not follow the link ignore it */
622 err = sysctl_follow_link(&head, &table, current->nsproxy);
623 if (err)
624 goto out;
625 }
626
627 ret = proc_sys_fill_cache(filp, dirent, filldir, head, table);
628 out:
629 sysctl_head_finish(head);
630 return ret;
631 }
632
633 static int scan(struct ctl_table_header *head, ctl_table *table,
634 unsigned long *pos, struct file *file,
635 void *dirent, filldir_t filldir)
636 {
637 int res;
638
639 if ((*pos)++ < file->f_pos)
640 return 0;
641
642 if (unlikely(S_ISLNK(table->mode)))
643 res = proc_sys_link_fill_cache(file, dirent, filldir, head, table);
644 else
645 res = proc_sys_fill_cache(file, dirent, filldir, head, table);
646
647 if (res == 0)
648 file->f_pos = *pos;
649
650 return res;
651 }
652
653 static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
654 {
655 struct dentry *dentry = filp->f_path.dentry;
656 struct inode *inode = dentry->d_inode;
657 struct ctl_table_header *head = grab_header(inode);
658 struct ctl_table_header *h = NULL;
659 struct ctl_table *entry;
660 struct ctl_dir *ctl_dir;
661 unsigned long pos;
662 int ret = -EINVAL;
663
664 if (IS_ERR(head))
665 return PTR_ERR(head);
666
667 ctl_dir = container_of(head, struct ctl_dir, header);
668
669 ret = 0;
670 /* Avoid a switch here: arm builds fail with missing __cmpdi2 */
671 if (filp->f_pos == 0) {
672 if (filldir(dirent, ".", 1, filp->f_pos,
673 inode->i_ino, DT_DIR) < 0)
674 goto out;
675 filp->f_pos++;
676 }
677 if (filp->f_pos == 1) {
678 if (filldir(dirent, "..", 2, filp->f_pos,
679 parent_ino(dentry), DT_DIR) < 0)
680 goto out;
681 filp->f_pos++;
682 }
683 pos = 2;
684
685 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
686 ret = scan(h, entry, &pos, filp, dirent, filldir);
687 if (ret) {
688 sysctl_head_finish(h);
689 break;
690 }
691 }
692 ret = 1;
693 out:
694 sysctl_head_finish(head);
695 return ret;
696 }
697
698 static int proc_sys_permission(struct inode *inode, int mask)
699 {
700 /*
701 * sysctl entries that are not writeable,
702 * are _NOT_ writeable, capabilities or not.
703 */
704 struct ctl_table_header *head;
705 struct ctl_table *table;
706 int error;
707
708 /* Executable files are not allowed under /proc/sys/ */
709 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
710 return -EACCES;
711
712 head = grab_header(inode);
713 if (IS_ERR(head))
714 return PTR_ERR(head);
715
716 table = PROC_I(inode)->sysctl_entry;
717 if (!table) /* global root - r-xr-xr-x */
718 error = mask & MAY_WRITE ? -EACCES : 0;
719 else /* Use the permissions on the sysctl table entry */
720 error = sysctl_perm(head->root, table, mask & ~MAY_NOT_BLOCK);
721
722 sysctl_head_finish(head);
723 return error;
724 }
725
726 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
727 {
728 struct inode *inode = dentry->d_inode;
729 int error;
730
731 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
732 return -EPERM;
733
734 error = inode_change_ok(inode, attr);
735 if (error)
736 return error;
737
738 if ((attr->ia_valid & ATTR_SIZE) &&
739 attr->ia_size != i_size_read(inode)) {
740 error = vmtruncate(inode, attr->ia_size);
741 if (error)
742 return error;
743 }
744
745 setattr_copy(inode, attr);
746 mark_inode_dirty(inode);
747 return 0;
748 }
749
750 static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
751 {
752 struct inode *inode = dentry->d_inode;
753 struct ctl_table_header *head = grab_header(inode);
754 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
755
756 if (IS_ERR(head))
757 return PTR_ERR(head);
758
759 generic_fillattr(inode, stat);
760 if (table)
761 stat->mode = (stat->mode & S_IFMT) | table->mode;
762
763 sysctl_head_finish(head);
764 return 0;
765 }
766
767 static const struct file_operations proc_sys_file_operations = {
768 .open = proc_sys_open,
769 .poll = proc_sys_poll,
770 .read = proc_sys_read,
771 .write = proc_sys_write,
772 .llseek = default_llseek,
773 };
774
775 static const struct file_operations proc_sys_dir_file_operations = {
776 .read = generic_read_dir,
777 .readdir = proc_sys_readdir,
778 .llseek = generic_file_llseek,
779 };
780
781 static const struct inode_operations proc_sys_inode_operations = {
782 .permission = proc_sys_permission,
783 .setattr = proc_sys_setattr,
784 .getattr = proc_sys_getattr,
785 };
786
787 static const struct inode_operations proc_sys_dir_operations = {
788 .lookup = proc_sys_lookup,
789 .permission = proc_sys_permission,
790 .setattr = proc_sys_setattr,
791 .getattr = proc_sys_getattr,
792 };
793
794 static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
795 {
796 if (flags & LOOKUP_RCU)
797 return -ECHILD;
798 return !PROC_I(dentry->d_inode)->sysctl->unregistering;
799 }
800
801 static int proc_sys_delete(const struct dentry *dentry)
802 {
803 return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
804 }
805
806 static int sysctl_is_seen(struct ctl_table_header *p)
807 {
808 struct ctl_table_set *set = p->set;
809 int res;
810 spin_lock(&sysctl_lock);
811 if (p->unregistering)
812 res = 0;
813 else if (!set->is_seen)
814 res = 1;
815 else
816 res = set->is_seen(set);
817 spin_unlock(&sysctl_lock);
818 return res;
819 }
820
821 static int proc_sys_compare(const struct dentry *parent,
822 const struct inode *pinode,
823 const struct dentry *dentry, const struct inode *inode,
824 unsigned int len, const char *str, const struct qstr *name)
825 {
826 struct ctl_table_header *head;
827 /* Although proc doesn't have negative dentries, rcu-walk means
828 * that inode here can be NULL */
829 /* AV: can it, indeed? */
830 if (!inode)
831 return 1;
832 if (name->len != len)
833 return 1;
834 if (memcmp(name->name, str, len))
835 return 1;
836 head = rcu_dereference(PROC_I(inode)->sysctl);
837 return !head || !sysctl_is_seen(head);
838 }
839
840 static const struct dentry_operations proc_sys_dentry_operations = {
841 .d_revalidate = proc_sys_revalidate,
842 .d_delete = proc_sys_delete,
843 .d_compare = proc_sys_compare,
844 };
845
846 static struct ctl_dir *find_subdir(struct ctl_dir *dir,
847 const char *name, int namelen)
848 {
849 struct ctl_table_header *head;
850 struct ctl_table *entry;
851
852 entry = find_entry(&head, dir, name, namelen);
853 if (!entry)
854 return ERR_PTR(-ENOENT);
855 if (!S_ISDIR(entry->mode))
856 return ERR_PTR(-ENOTDIR);
857 return container_of(head, struct ctl_dir, header);
858 }
859
860 static struct ctl_dir *new_dir(struct ctl_table_set *set,
861 const char *name, int namelen)
862 {
863 struct ctl_table *table;
864 struct ctl_dir *new;
865 struct ctl_node *node;
866 char *new_name;
867
868 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
869 sizeof(struct ctl_table)*2 + namelen + 1,
870 GFP_KERNEL);
871 if (!new)
872 return NULL;
873
874 node = (struct ctl_node *)(new + 1);
875 table = (struct ctl_table *)(node + 1);
876 new_name = (char *)(table + 2);
877 memcpy(new_name, name, namelen);
878 new_name[namelen] = '\0';
879 table[0].procname = new_name;
880 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
881 init_header(&new->header, set->dir.header.root, set, node, table);
882
883 return new;
884 }
885
886 /**
887 * get_subdir - find or create a subdir with the specified name.
888 * @dir: Directory to create the subdirectory in
889 * @name: The name of the subdirectory to find or create
890 * @namelen: The length of name
891 *
892 * Takes a directory with an elevated reference count so we know that
893 * if we drop the lock the directory will not go away. Upon success
894 * the reference is moved from @dir to the returned subdirectory.
895 * Upon error an error code is returned and the reference on @dir is
896 * simply dropped.
897 */
898 static struct ctl_dir *get_subdir(struct ctl_dir *dir,
899 const char *name, int namelen)
900 {
901 struct ctl_table_set *set = dir->header.set;
902 struct ctl_dir *subdir, *new = NULL;
903 int err;
904
905 spin_lock(&sysctl_lock);
906 subdir = find_subdir(dir, name, namelen);
907 if (!IS_ERR(subdir))
908 goto found;
909 if (PTR_ERR(subdir) != -ENOENT)
910 goto failed;
911
912 spin_unlock(&sysctl_lock);
913 new = new_dir(set, name, namelen);
914 spin_lock(&sysctl_lock);
915 subdir = ERR_PTR(-ENOMEM);
916 if (!new)
917 goto failed;
918
919 /* Was the subdir added while we dropped the lock? */
920 subdir = find_subdir(dir, name, namelen);
921 if (!IS_ERR(subdir))
922 goto found;
923 if (PTR_ERR(subdir) != -ENOENT)
924 goto failed;
925
926 /* Nope. Use the our freshly made directory entry. */
927 err = insert_header(dir, &new->header);
928 subdir = ERR_PTR(err);
929 if (err)
930 goto failed;
931 subdir = new;
932 found:
933 subdir->header.nreg++;
934 failed:
935 if (unlikely(IS_ERR(subdir))) {
936 printk(KERN_ERR "sysctl could not get directory: ");
937 sysctl_print_dir(dir);
938 printk(KERN_CONT "/%*.*s %ld\n",
939 namelen, namelen, name, PTR_ERR(subdir));
940 }
941 drop_sysctl_table(&dir->header);
942 if (new)
943 drop_sysctl_table(&new->header);
944 spin_unlock(&sysctl_lock);
945 return subdir;
946 }
947
948 static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
949 {
950 struct ctl_dir *parent;
951 const char *procname;
952 if (!dir->header.parent)
953 return &set->dir;
954 parent = xlate_dir(set, dir->header.parent);
955 if (IS_ERR(parent))
956 return parent;
957 procname = dir->header.ctl_table[0].procname;
958 return find_subdir(parent, procname, strlen(procname));
959 }
960
961 static int sysctl_follow_link(struct ctl_table_header **phead,
962 struct ctl_table **pentry, struct nsproxy *namespaces)
963 {
964 struct ctl_table_header *head;
965 struct ctl_table_root *root;
966 struct ctl_table_set *set;
967 struct ctl_table *entry;
968 struct ctl_dir *dir;
969 int ret;
970
971 ret = 0;
972 spin_lock(&sysctl_lock);
973 root = (*pentry)->data;
974 set = lookup_header_set(root, namespaces);
975 dir = xlate_dir(set, (*phead)->parent);
976 if (IS_ERR(dir))
977 ret = PTR_ERR(dir);
978 else {
979 const char *procname = (*pentry)->procname;
980 head = NULL;
981 entry = find_entry(&head, dir, procname, strlen(procname));
982 ret = -ENOENT;
983 if (entry && use_table(head)) {
984 unuse_table(*phead);
985 *phead = head;
986 *pentry = entry;
987 ret = 0;
988 }
989 }
990
991 spin_unlock(&sysctl_lock);
992 return ret;
993 }
994
995 static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
996 {
997 struct va_format vaf;
998 va_list args;
999
1000 va_start(args, fmt);
1001 vaf.fmt = fmt;
1002 vaf.va = &args;
1003
1004 printk(KERN_ERR "sysctl table check failed: %s/%s %pV\n",
1005 path, table->procname, &vaf);
1006
1007 va_end(args);
1008 return -EINVAL;
1009 }
1010
1011 static int sysctl_check_table(const char *path, struct ctl_table *table)
1012 {
1013 int err = 0;
1014 for (; table->procname; table++) {
1015 if (table->child)
1016 err = sysctl_err(path, table, "Not a file");
1017
1018 if ((table->proc_handler == proc_dostring) ||
1019 (table->proc_handler == proc_dointvec) ||
1020 (table->proc_handler == proc_dointvec_minmax) ||
1021 (table->proc_handler == proc_dointvec_jiffies) ||
1022 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1023 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1024 (table->proc_handler == proc_doulongvec_minmax) ||
1025 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1026 if (!table->data)
1027 err = sysctl_err(path, table, "No data");
1028 if (!table->maxlen)
1029 err = sysctl_err(path, table, "No maxlen");
1030 }
1031 if (!table->proc_handler)
1032 err = sysctl_err(path, table, "No proc_handler");
1033
1034 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1035 err = sysctl_err(path, table, "bogus .mode 0%o",
1036 table->mode);
1037 }
1038 return err;
1039 }
1040
1041 static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1042 struct ctl_table_root *link_root)
1043 {
1044 struct ctl_table *link_table, *entry, *link;
1045 struct ctl_table_header *links;
1046 struct ctl_node *node;
1047 char *link_name;
1048 int nr_entries, name_bytes;
1049
1050 name_bytes = 0;
1051 nr_entries = 0;
1052 for (entry = table; entry->procname; entry++) {
1053 nr_entries++;
1054 name_bytes += strlen(entry->procname) + 1;
1055 }
1056
1057 links = kzalloc(sizeof(struct ctl_table_header) +
1058 sizeof(struct ctl_node)*nr_entries +
1059 sizeof(struct ctl_table)*(nr_entries + 1) +
1060 name_bytes,
1061 GFP_KERNEL);
1062
1063 if (!links)
1064 return NULL;
1065
1066 node = (struct ctl_node *)(links + 1);
1067 link_table = (struct ctl_table *)(node + nr_entries);
1068 link_name = (char *)&link_table[nr_entries + 1];
1069
1070 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1071 int len = strlen(entry->procname) + 1;
1072 memcpy(link_name, entry->procname, len);
1073 link->procname = link_name;
1074 link->mode = S_IFLNK|S_IRWXUGO;
1075 link->data = link_root;
1076 link_name += len;
1077 }
1078 init_header(links, dir->header.root, dir->header.set, node, link_table);
1079 links->nreg = nr_entries;
1080
1081 return links;
1082 }
1083
1084 static bool get_links(struct ctl_dir *dir,
1085 struct ctl_table *table, struct ctl_table_root *link_root)
1086 {
1087 struct ctl_table_header *head;
1088 struct ctl_table *entry, *link;
1089
1090 /* Are there links available for every entry in table? */
1091 for (entry = table; entry->procname; entry++) {
1092 const char *procname = entry->procname;
1093 link = find_entry(&head, dir, procname, strlen(procname));
1094 if (!link)
1095 return false;
1096 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1097 continue;
1098 if (S_ISLNK(link->mode) && (link->data == link_root))
1099 continue;
1100 return false;
1101 }
1102
1103 /* The checks passed. Increase the registration count on the links */
1104 for (entry = table; entry->procname; entry++) {
1105 const char *procname = entry->procname;
1106 link = find_entry(&head, dir, procname, strlen(procname));
1107 head->nreg++;
1108 }
1109 return true;
1110 }
1111
1112 static int insert_links(struct ctl_table_header *head)
1113 {
1114 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1115 struct ctl_dir *core_parent = NULL;
1116 struct ctl_table_header *links;
1117 int err;
1118
1119 if (head->set == root_set)
1120 return 0;
1121
1122 core_parent = xlate_dir(root_set, head->parent);
1123 if (IS_ERR(core_parent))
1124 return 0;
1125
1126 if (get_links(core_parent, head->ctl_table, head->root))
1127 return 0;
1128
1129 core_parent->header.nreg++;
1130 spin_unlock(&sysctl_lock);
1131
1132 links = new_links(core_parent, head->ctl_table, head->root);
1133
1134 spin_lock(&sysctl_lock);
1135 err = -ENOMEM;
1136 if (!links)
1137 goto out;
1138
1139 err = 0;
1140 if (get_links(core_parent, head->ctl_table, head->root)) {
1141 kfree(links);
1142 goto out;
1143 }
1144
1145 err = insert_header(core_parent, links);
1146 if (err)
1147 kfree(links);
1148 out:
1149 drop_sysctl_table(&core_parent->header);
1150 return err;
1151 }
1152
1153 /**
1154 * __register_sysctl_table - register a leaf sysctl table
1155 * @set: Sysctl tree to register on
1156 * @path: The path to the directory the sysctl table is in.
1157 * @table: the top-level table structure
1158 *
1159 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1160 * array. A completely 0 filled entry terminates the table.
1161 *
1162 * The members of the &struct ctl_table structure are used as follows:
1163 *
1164 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1165 * enter a sysctl file
1166 *
1167 * data - a pointer to data for use by proc_handler
1168 *
1169 * maxlen - the maximum size in bytes of the data
1170 *
1171 * mode - the file permissions for the /proc/sys file
1172 *
1173 * child - must be %NULL.
1174 *
1175 * proc_handler - the text handler routine (described below)
1176 *
1177 * extra1, extra2 - extra pointers usable by the proc handler routines
1178 *
1179 * Leaf nodes in the sysctl tree will be represented by a single file
1180 * under /proc; non-leaf nodes will be represented by directories.
1181 *
1182 * There must be a proc_handler routine for any terminal nodes.
1183 * Several default handlers are available to cover common cases -
1184 *
1185 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1186 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1187 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1188 *
1189 * It is the handler's job to read the input buffer from user memory
1190 * and process it. The handler should return 0 on success.
1191 *
1192 * This routine returns %NULL on a failure to register, and a pointer
1193 * to the table header on success.
1194 */
1195 struct ctl_table_header *__register_sysctl_table(
1196 struct ctl_table_set *set,
1197 const char *path, struct ctl_table *table)
1198 {
1199 struct ctl_table_root *root = set->dir.header.root;
1200 struct ctl_table_header *header;
1201 const char *name, *nextname;
1202 struct ctl_dir *dir;
1203 struct ctl_table *entry;
1204 struct ctl_node *node;
1205 int nr_entries = 0;
1206
1207 for (entry = table; entry->procname; entry++)
1208 nr_entries++;
1209
1210 header = kzalloc(sizeof(struct ctl_table_header) +
1211 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1212 if (!header)
1213 return NULL;
1214
1215 node = (struct ctl_node *)(header + 1);
1216 init_header(header, root, set, node, table);
1217 if (sysctl_check_table(path, table))
1218 goto fail;
1219
1220 spin_lock(&sysctl_lock);
1221 dir = &set->dir;
1222 /* Reference moved down the diretory tree get_subdir */
1223 dir->header.nreg++;
1224 spin_unlock(&sysctl_lock);
1225
1226 /* Find the directory for the ctl_table */
1227 for (name = path; name; name = nextname) {
1228 int namelen;
1229 nextname = strchr(name, '/');
1230 if (nextname) {
1231 namelen = nextname - name;
1232 nextname++;
1233 } else {
1234 namelen = strlen(name);
1235 }
1236 if (namelen == 0)
1237 continue;
1238
1239 dir = get_subdir(dir, name, namelen);
1240 if (IS_ERR(dir))
1241 goto fail;
1242 }
1243
1244 spin_lock(&sysctl_lock);
1245 if (insert_header(dir, header))
1246 goto fail_put_dir_locked;
1247
1248 drop_sysctl_table(&dir->header);
1249 spin_unlock(&sysctl_lock);
1250
1251 return header;
1252
1253 fail_put_dir_locked:
1254 drop_sysctl_table(&dir->header);
1255 spin_unlock(&sysctl_lock);
1256 fail:
1257 kfree(header);
1258 dump_stack();
1259 return NULL;
1260 }
1261
1262 /**
1263 * register_sysctl - register a sysctl table
1264 * @path: The path to the directory the sysctl table is in.
1265 * @table: the table structure
1266 *
1267 * Register a sysctl table. @table should be a filled in ctl_table
1268 * array. A completely 0 filled entry terminates the table.
1269 *
1270 * See __register_sysctl_table for more details.
1271 */
1272 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1273 {
1274 return __register_sysctl_table(&sysctl_table_root.default_set,
1275 path, table);
1276 }
1277 EXPORT_SYMBOL(register_sysctl);
1278
1279 static char *append_path(const char *path, char *pos, const char *name)
1280 {
1281 int namelen;
1282 namelen = strlen(name);
1283 if (((pos - path) + namelen + 2) >= PATH_MAX)
1284 return NULL;
1285 memcpy(pos, name, namelen);
1286 pos[namelen] = '/';
1287 pos[namelen + 1] = '\0';
1288 pos += namelen + 1;
1289 return pos;
1290 }
1291
1292 static int count_subheaders(struct ctl_table *table)
1293 {
1294 int has_files = 0;
1295 int nr_subheaders = 0;
1296 struct ctl_table *entry;
1297
1298 /* special case: no directory and empty directory */
1299 if (!table || !table->procname)
1300 return 1;
1301
1302 for (entry = table; entry->procname; entry++) {
1303 if (entry->child)
1304 nr_subheaders += count_subheaders(entry->child);
1305 else
1306 has_files = 1;
1307 }
1308 return nr_subheaders + has_files;
1309 }
1310
1311 static int register_leaf_sysctl_tables(const char *path, char *pos,
1312 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1313 struct ctl_table *table)
1314 {
1315 struct ctl_table *ctl_table_arg = NULL;
1316 struct ctl_table *entry, *files;
1317 int nr_files = 0;
1318 int nr_dirs = 0;
1319 int err = -ENOMEM;
1320
1321 for (entry = table; entry->procname; entry++) {
1322 if (entry->child)
1323 nr_dirs++;
1324 else
1325 nr_files++;
1326 }
1327
1328 files = table;
1329 /* If there are mixed files and directories we need a new table */
1330 if (nr_dirs && nr_files) {
1331 struct ctl_table *new;
1332 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1333 GFP_KERNEL);
1334 if (!files)
1335 goto out;
1336
1337 ctl_table_arg = files;
1338 for (new = files, entry = table; entry->procname; entry++) {
1339 if (entry->child)
1340 continue;
1341 *new = *entry;
1342 new++;
1343 }
1344 }
1345
1346 /* Register everything except a directory full of subdirectories */
1347 if (nr_files || !nr_dirs) {
1348 struct ctl_table_header *header;
1349 header = __register_sysctl_table(set, path, files);
1350 if (!header) {
1351 kfree(ctl_table_arg);
1352 goto out;
1353 }
1354
1355 /* Remember if we need to free the file table */
1356 header->ctl_table_arg = ctl_table_arg;
1357 **subheader = header;
1358 (*subheader)++;
1359 }
1360
1361 /* Recurse into the subdirectories. */
1362 for (entry = table; entry->procname; entry++) {
1363 char *child_pos;
1364
1365 if (!entry->child)
1366 continue;
1367
1368 err = -ENAMETOOLONG;
1369 child_pos = append_path(path, pos, entry->procname);
1370 if (!child_pos)
1371 goto out;
1372
1373 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1374 set, entry->child);
1375 pos[0] = '\0';
1376 if (err)
1377 goto out;
1378 }
1379 err = 0;
1380 out:
1381 /* On failure our caller will unregister all registered subheaders */
1382 return err;
1383 }
1384
1385 /**
1386 * __register_sysctl_paths - register a sysctl table hierarchy
1387 * @set: Sysctl tree to register on
1388 * @path: The path to the directory the sysctl table is in.
1389 * @table: the top-level table structure
1390 *
1391 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1392 * array. A completely 0 filled entry terminates the table.
1393 *
1394 * See __register_sysctl_table for more details.
1395 */
1396 struct ctl_table_header *__register_sysctl_paths(
1397 struct ctl_table_set *set,
1398 const struct ctl_path *path, struct ctl_table *table)
1399 {
1400 struct ctl_table *ctl_table_arg = table;
1401 int nr_subheaders = count_subheaders(table);
1402 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1403 const struct ctl_path *component;
1404 char *new_path, *pos;
1405
1406 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1407 if (!new_path)
1408 return NULL;
1409
1410 pos[0] = '\0';
1411 for (component = path; component->procname; component++) {
1412 pos = append_path(new_path, pos, component->procname);
1413 if (!pos)
1414 goto out;
1415 }
1416 while (table->procname && table->child && !table[1].procname) {
1417 pos = append_path(new_path, pos, table->procname);
1418 if (!pos)
1419 goto out;
1420 table = table->child;
1421 }
1422 if (nr_subheaders == 1) {
1423 header = __register_sysctl_table(set, new_path, table);
1424 if (header)
1425 header->ctl_table_arg = ctl_table_arg;
1426 } else {
1427 header = kzalloc(sizeof(*header) +
1428 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1429 if (!header)
1430 goto out;
1431
1432 subheaders = (struct ctl_table_header **) (header + 1);
1433 subheader = subheaders;
1434 header->ctl_table_arg = ctl_table_arg;
1435
1436 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1437 set, table))
1438 goto err_register_leaves;
1439 }
1440
1441 out:
1442 kfree(new_path);
1443 return header;
1444
1445 err_register_leaves:
1446 while (subheader > subheaders) {
1447 struct ctl_table_header *subh = *(--subheader);
1448 struct ctl_table *table = subh->ctl_table_arg;
1449 unregister_sysctl_table(subh);
1450 kfree(table);
1451 }
1452 kfree(header);
1453 header = NULL;
1454 goto out;
1455 }
1456
1457 /**
1458 * register_sysctl_table_path - register a sysctl table hierarchy
1459 * @path: The path to the directory the sysctl table is in.
1460 * @table: the top-level table structure
1461 *
1462 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1463 * array. A completely 0 filled entry terminates the table.
1464 *
1465 * See __register_sysctl_paths for more details.
1466 */
1467 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1468 struct ctl_table *table)
1469 {
1470 return __register_sysctl_paths(&sysctl_table_root.default_set,
1471 path, table);
1472 }
1473 EXPORT_SYMBOL(register_sysctl_paths);
1474
1475 /**
1476 * register_sysctl_table - register a sysctl table hierarchy
1477 * @table: the top-level table structure
1478 *
1479 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1480 * array. A completely 0 filled entry terminates the table.
1481 *
1482 * See register_sysctl_paths for more details.
1483 */
1484 struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1485 {
1486 static const struct ctl_path null_path[] = { {} };
1487
1488 return register_sysctl_paths(null_path, table);
1489 }
1490 EXPORT_SYMBOL(register_sysctl_table);
1491
1492 static void put_links(struct ctl_table_header *header)
1493 {
1494 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1495 struct ctl_table_root *root = header->root;
1496 struct ctl_dir *parent = header->parent;
1497 struct ctl_dir *core_parent;
1498 struct ctl_table *entry;
1499
1500 if (header->set == root_set)
1501 return;
1502
1503 core_parent = xlate_dir(root_set, parent);
1504 if (IS_ERR(core_parent))
1505 return;
1506
1507 for (entry = header->ctl_table; entry->procname; entry++) {
1508 struct ctl_table_header *link_head;
1509 struct ctl_table *link;
1510 const char *name = entry->procname;
1511
1512 link = find_entry(&link_head, core_parent, name, strlen(name));
1513 if (link &&
1514 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1515 (S_ISLNK(link->mode) && (link->data == root)))) {
1516 drop_sysctl_table(link_head);
1517 }
1518 else {
1519 printk(KERN_ERR "sysctl link missing during unregister: ");
1520 sysctl_print_dir(parent);
1521 printk(KERN_CONT "/%s\n", name);
1522 }
1523 }
1524 }
1525
1526 static void drop_sysctl_table(struct ctl_table_header *header)
1527 {
1528 struct ctl_dir *parent = header->parent;
1529
1530 if (--header->nreg)
1531 return;
1532
1533 put_links(header);
1534 start_unregistering(header);
1535 if (!--header->count)
1536 kfree_rcu(header, rcu);
1537
1538 if (parent)
1539 drop_sysctl_table(&parent->header);
1540 }
1541
1542 /**
1543 * unregister_sysctl_table - unregister a sysctl table hierarchy
1544 * @header: the header returned from register_sysctl_table
1545 *
1546 * Unregisters the sysctl table and all children. proc entries may not
1547 * actually be removed until they are no longer used by anyone.
1548 */
1549 void unregister_sysctl_table(struct ctl_table_header * header)
1550 {
1551 int nr_subheaders;
1552 might_sleep();
1553
1554 if (header == NULL)
1555 return;
1556
1557 nr_subheaders = count_subheaders(header->ctl_table_arg);
1558 if (unlikely(nr_subheaders > 1)) {
1559 struct ctl_table_header **subheaders;
1560 int i;
1561
1562 subheaders = (struct ctl_table_header **)(header + 1);
1563 for (i = nr_subheaders -1; i >= 0; i--) {
1564 struct ctl_table_header *subh = subheaders[i];
1565 struct ctl_table *table = subh->ctl_table_arg;
1566 unregister_sysctl_table(subh);
1567 kfree(table);
1568 }
1569 kfree(header);
1570 return;
1571 }
1572
1573 spin_lock(&sysctl_lock);
1574 drop_sysctl_table(header);
1575 spin_unlock(&sysctl_lock);
1576 }
1577 EXPORT_SYMBOL(unregister_sysctl_table);
1578
1579 void setup_sysctl_set(struct ctl_table_set *set,
1580 struct ctl_table_root *root,
1581 int (*is_seen)(struct ctl_table_set *))
1582 {
1583 memset(set, 0, sizeof(*set));
1584 set->is_seen = is_seen;
1585 init_header(&set->dir.header, root, set, NULL, root_table);
1586 }
1587
1588 void retire_sysctl_set(struct ctl_table_set *set)
1589 {
1590 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1591 }
1592
1593 int __init proc_sys_init(void)
1594 {
1595 struct proc_dir_entry *proc_sys_root;
1596
1597 proc_sys_root = proc_mkdir("sys", NULL);
1598 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1599 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1600 proc_sys_root->nlink = 0;
1601
1602 return sysctl_init();
1603 }
Linus' kernel tree