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Merge branch 'next/drivers' into HEAD
[deliverable/linux.git] / fs / proc / proc_sysctl.c
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 return 0;
146 }
147
148 static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
149 {
150 struct rb_node *node = &head->node[entry - head->ctl_table].node;
151
152 rb_erase(node, &head->parent->root);
153 }
154
155 static void init_header(struct ctl_table_header *head,
156 struct ctl_table_root *root, struct ctl_table_set *set,
157 struct ctl_node *node, struct ctl_table *table)
158 {
159 head->ctl_table = table;
160 head->ctl_table_arg = table;
161 head->used = 0;
162 head->count = 1;
163 head->nreg = 1;
164 head->unregistering = NULL;
165 head->root = root;
166 head->set = set;
167 head->parent = NULL;
168 head->node = node;
169 if (node) {
170 struct ctl_table *entry;
171 for (entry = table; entry->procname; entry++, node++) {
172 rb_init_node(&node->node);
173 node->header = head;
174 }
175 }
176 }
177
178 static void erase_header(struct ctl_table_header *head)
179 {
180 struct ctl_table *entry;
181 for (entry = head->ctl_table; entry->procname; entry++)
182 erase_entry(head, entry);
183 }
184
185 static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
186 {
187 struct ctl_table *entry;
188 int err;
189
190 dir->header.nreg++;
191 header->parent = dir;
192 err = insert_links(header);
193 if (err)
194 goto fail_links;
195 for (entry = header->ctl_table; entry->procname; entry++) {
196 err = insert_entry(header, entry);
197 if (err)
198 goto fail;
199 }
200 return 0;
201 fail:
202 erase_header(header);
203 put_links(header);
204 fail_links:
205 header->parent = NULL;
206 drop_sysctl_table(&dir->header);
207 return err;
208 }
209
210 /* called under sysctl_lock */
211 static int use_table(struct ctl_table_header *p)
212 {
213 if (unlikely(p->unregistering))
214 return 0;
215 p->used++;
216 return 1;
217 }
218
219 /* called under sysctl_lock */
220 static void unuse_table(struct ctl_table_header *p)
221 {
222 if (!--p->used)
223 if (unlikely(p->unregistering))
224 complete(p->unregistering);
225 }
226
227 /* called under sysctl_lock, will reacquire if has to wait */
228 static void start_unregistering(struct ctl_table_header *p)
229 {
230 /*
231 * if p->used is 0, nobody will ever touch that entry again;
232 * we'll eliminate all paths to it before dropping sysctl_lock
233 */
234 if (unlikely(p->used)) {
235 struct completion wait;
236 init_completion(&wait);
237 p->unregistering = &wait;
238 spin_unlock(&sysctl_lock);
239 wait_for_completion(&wait);
240 spin_lock(&sysctl_lock);
241 } else {
242 /* anything non-NULL; we'll never dereference it */
243 p->unregistering = ERR_PTR(-EINVAL);
244 }
245 /*
246 * do not remove from the list until nobody holds it; walking the
247 * list in do_sysctl() relies on that.
248 */
249 erase_header(p);
250 }
251
252 static void sysctl_head_get(struct ctl_table_header *head)
253 {
254 spin_lock(&sysctl_lock);
255 head->count++;
256 spin_unlock(&sysctl_lock);
257 }
258
259 void sysctl_head_put(struct ctl_table_header *head)
260 {
261 spin_lock(&sysctl_lock);
262 if (!--head->count)
263 kfree_rcu(head, rcu);
264 spin_unlock(&sysctl_lock);
265 }
266
267 static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
268 {
269 if (!head)
270 BUG();
271 spin_lock(&sysctl_lock);
272 if (!use_table(head))
273 head = ERR_PTR(-ENOENT);
274 spin_unlock(&sysctl_lock);
275 return head;
276 }
277
278 static void sysctl_head_finish(struct ctl_table_header *head)
279 {
280 if (!head)
281 return;
282 spin_lock(&sysctl_lock);
283 unuse_table(head);
284 spin_unlock(&sysctl_lock);
285 }
286
287 static struct ctl_table_set *
288 lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces)
289 {
290 struct ctl_table_set *set = &root->default_set;
291 if (root->lookup)
292 set = root->lookup(root, namespaces);
293 return set;
294 }
295
296 static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
297 struct ctl_dir *dir,
298 const char *name, int namelen)
299 {
300 struct ctl_table_header *head;
301 struct ctl_table *entry;
302
303 spin_lock(&sysctl_lock);
304 entry = find_entry(&head, dir, name, namelen);
305 if (entry && use_table(head))
306 *phead = head;
307 else
308 entry = NULL;
309 spin_unlock(&sysctl_lock);
310 return entry;
311 }
312
313 static struct ctl_node *first_usable_entry(struct rb_node *node)
314 {
315 struct ctl_node *ctl_node;
316
317 for (;node; node = rb_next(node)) {
318 ctl_node = rb_entry(node, struct ctl_node, node);
319 if (use_table(ctl_node->header))
320 return ctl_node;
321 }
322 return NULL;
323 }
324
325 static void first_entry(struct ctl_dir *dir,
326 struct ctl_table_header **phead, struct ctl_table **pentry)
327 {
328 struct ctl_table_header *head = NULL;
329 struct ctl_table *entry = NULL;
330 struct ctl_node *ctl_node;
331
332 spin_lock(&sysctl_lock);
333 ctl_node = first_usable_entry(rb_first(&dir->root));
334 spin_unlock(&sysctl_lock);
335 if (ctl_node) {
336 head = ctl_node->header;
337 entry = &head->ctl_table[ctl_node - head->node];
338 }
339 *phead = head;
340 *pentry = entry;
341 }
342
343 static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
344 {
345 struct ctl_table_header *head = *phead;
346 struct ctl_table *entry = *pentry;
347 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
348
349 spin_lock(&sysctl_lock);
350 unuse_table(head);
351
352 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
353 spin_unlock(&sysctl_lock);
354 head = NULL;
355 if (ctl_node) {
356 head = ctl_node->header;
357 entry = &head->ctl_table[ctl_node - head->node];
358 }
359 *phead = head;
360 *pentry = entry;
361 }
362
363 void register_sysctl_root(struct ctl_table_root *root)
364 {
365 }
366
367 /*
368 * sysctl_perm does NOT grant the superuser all rights automatically, because
369 * some sysctl variables are readonly even to root.
370 */
371
372 static int test_perm(int mode, int op)
373 {
374 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
375 mode >>= 6;
376 else if (in_egroup_p(GLOBAL_ROOT_GID))
377 mode >>= 3;
378 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
379 return 0;
380 return -EACCES;
381 }
382
383 static int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op)
384 {
385 int mode;
386
387 if (root->permissions)
388 mode = root->permissions(root, current->nsproxy, table);
389 else
390 mode = table->mode;
391
392 return test_perm(mode, op);
393 }
394
395 static struct inode *proc_sys_make_inode(struct super_block *sb,
396 struct ctl_table_header *head, struct ctl_table *table)
397 {
398 struct inode *inode;
399 struct proc_inode *ei;
400
401 inode = new_inode(sb);
402 if (!inode)
403 goto out;
404
405 inode->i_ino = get_next_ino();
406
407 sysctl_head_get(head);
408 ei = PROC_I(inode);
409 ei->sysctl = head;
410 ei->sysctl_entry = table;
411
412 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
413 inode->i_mode = table->mode;
414 if (!S_ISDIR(table->mode)) {
415 inode->i_mode |= S_IFREG;
416 inode->i_op = &proc_sys_inode_operations;
417 inode->i_fop = &proc_sys_file_operations;
418 } else {
419 inode->i_mode |= S_IFDIR;
420 inode->i_op = &proc_sys_dir_operations;
421 inode->i_fop = &proc_sys_dir_file_operations;
422 }
423 out:
424 return inode;
425 }
426
427 static struct ctl_table_header *grab_header(struct inode *inode)
428 {
429 struct ctl_table_header *head = PROC_I(inode)->sysctl;
430 if (!head)
431 head = &sysctl_table_root.default_set.dir.header;
432 return sysctl_head_grab(head);
433 }
434
435 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
436 unsigned int flags)
437 {
438 struct ctl_table_header *head = grab_header(dir);
439 struct ctl_table_header *h = NULL;
440 struct qstr *name = &dentry->d_name;
441 struct ctl_table *p;
442 struct inode *inode;
443 struct dentry *err = ERR_PTR(-ENOENT);
444 struct ctl_dir *ctl_dir;
445 int ret;
446
447 if (IS_ERR(head))
448 return ERR_CAST(head);
449
450 ctl_dir = container_of(head, struct ctl_dir, header);
451
452 p = lookup_entry(&h, ctl_dir, name->name, name->len);
453 if (!p)
454 goto out;
455
456 if (S_ISLNK(p->mode)) {
457 ret = sysctl_follow_link(&h, &p, current->nsproxy);
458 err = ERR_PTR(ret);
459 if (ret)
460 goto out;
461 }
462
463 err = ERR_PTR(-ENOMEM);
464 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
465 if (!inode)
466 goto out;
467
468 err = NULL;
469 d_set_d_op(dentry, &proc_sys_dentry_operations);
470 d_add(dentry, inode);
471
472 out:
473 if (h)
474 sysctl_head_finish(h);
475 sysctl_head_finish(head);
476 return err;
477 }
478
479 static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
480 size_t count, loff_t *ppos, int write)
481 {
482 struct inode *inode = filp->f_path.dentry->d_inode;
483 struct ctl_table_header *head = grab_header(inode);
484 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
485 ssize_t error;
486 size_t res;
487
488 if (IS_ERR(head))
489 return PTR_ERR(head);
490
491 /*
492 * At this point we know that the sysctl was not unregistered
493 * and won't be until we finish.
494 */
495 error = -EPERM;
496 if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
497 goto out;
498
499 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
500 error = -EINVAL;
501 if (!table->proc_handler)
502 goto out;
503
504 /* careful: calling conventions are nasty here */
505 res = count;
506 error = table->proc_handler(table, write, buf, &res, ppos);
507 if (!error)
508 error = res;
509 out:
510 sysctl_head_finish(head);
511
512 return error;
513 }
514
515 static ssize_t proc_sys_read(struct file *filp, char __user *buf,
516 size_t count, loff_t *ppos)
517 {
518 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
519 }
520
521 static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
522 size_t count, loff_t *ppos)
523 {
524 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
525 }
526
527 static int proc_sys_open(struct inode *inode, struct file *filp)
528 {
529 struct ctl_table_header *head = grab_header(inode);
530 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
531
532 /* sysctl was unregistered */
533 if (IS_ERR(head))
534 return PTR_ERR(head);
535
536 if (table->poll)
537 filp->private_data = proc_sys_poll_event(table->poll);
538
539 sysctl_head_finish(head);
540
541 return 0;
542 }
543
544 static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
545 {
546 struct inode *inode = filp->f_path.dentry->d_inode;
547 struct ctl_table_header *head = grab_header(inode);
548 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
549 unsigned int ret = DEFAULT_POLLMASK;
550 unsigned long event;
551
552 /* sysctl was unregistered */
553 if (IS_ERR(head))
554 return POLLERR | POLLHUP;
555
556 if (!table->proc_handler)
557 goto out;
558
559 if (!table->poll)
560 goto out;
561
562 event = (unsigned long)filp->private_data;
563 poll_wait(filp, &table->poll->wait, wait);
564
565 if (event != atomic_read(&table->poll->event)) {
566 filp->private_data = proc_sys_poll_event(table->poll);
567 ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI;
568 }
569
570 out:
571 sysctl_head_finish(head);
572
573 return ret;
574 }
575
576 static int proc_sys_fill_cache(struct file *filp, void *dirent,
577 filldir_t filldir,
578 struct ctl_table_header *head,
579 struct ctl_table *table)
580 {
581 struct dentry *child, *dir = filp->f_path.dentry;
582 struct inode *inode;
583 struct qstr qname;
584 ino_t ino = 0;
585 unsigned type = DT_UNKNOWN;
586
587 qname.name = table->procname;
588 qname.len = strlen(table->procname);
589 qname.hash = full_name_hash(qname.name, qname.len);
590
591 child = d_lookup(dir, &qname);
592 if (!child) {
593 child = d_alloc(dir, &qname);
594 if (child) {
595 inode = proc_sys_make_inode(dir->d_sb, head, table);
596 if (!inode) {
597 dput(child);
598 return -ENOMEM;
599 } else {
600 d_set_d_op(child, &proc_sys_dentry_operations);
601 d_add(child, inode);
602 }
603 } else {
604 return -ENOMEM;
605 }
606 }
607 inode = child->d_inode;
608 ino = inode->i_ino;
609 type = inode->i_mode >> 12;
610 dput(child);
611 return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
612 }
613
614 static int proc_sys_link_fill_cache(struct file *filp, void *dirent,
615 filldir_t filldir,
616 struct ctl_table_header *head,
617 struct ctl_table *table)
618 {
619 int err, ret = 0;
620 head = sysctl_head_grab(head);
621
622 if (S_ISLNK(table->mode)) {
623 /* It is not an error if we can not follow the link ignore it */
624 err = sysctl_follow_link(&head, &table, current->nsproxy);
625 if (err)
626 goto out;
627 }
628
629 ret = proc_sys_fill_cache(filp, dirent, filldir, head, table);
630 out:
631 sysctl_head_finish(head);
632 return ret;
633 }
634
635 static int scan(struct ctl_table_header *head, ctl_table *table,
636 unsigned long *pos, struct file *file,
637 void *dirent, filldir_t filldir)
638 {
639 int res;
640
641 if ((*pos)++ < file->f_pos)
642 return 0;
643
644 if (unlikely(S_ISLNK(table->mode)))
645 res = proc_sys_link_fill_cache(file, dirent, filldir, head, table);
646 else
647 res = proc_sys_fill_cache(file, dirent, filldir, head, table);
648
649 if (res == 0)
650 file->f_pos = *pos;
651
652 return res;
653 }
654
655 static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
656 {
657 struct dentry *dentry = filp->f_path.dentry;
658 struct inode *inode = dentry->d_inode;
659 struct ctl_table_header *head = grab_header(inode);
660 struct ctl_table_header *h = NULL;
661 struct ctl_table *entry;
662 struct ctl_dir *ctl_dir;
663 unsigned long pos;
664 int ret = -EINVAL;
665
666 if (IS_ERR(head))
667 return PTR_ERR(head);
668
669 ctl_dir = container_of(head, struct ctl_dir, header);
670
671 ret = 0;
672 /* Avoid a switch here: arm builds fail with missing __cmpdi2 */
673 if (filp->f_pos == 0) {
674 if (filldir(dirent, ".", 1, filp->f_pos,
675 inode->i_ino, DT_DIR) < 0)
676 goto out;
677 filp->f_pos++;
678 }
679 if (filp->f_pos == 1) {
680 if (filldir(dirent, "..", 2, filp->f_pos,
681 parent_ino(dentry), DT_DIR) < 0)
682 goto out;
683 filp->f_pos++;
684 }
685 pos = 2;
686
687 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
688 ret = scan(h, entry, &pos, filp, dirent, filldir);
689 if (ret) {
690 sysctl_head_finish(h);
691 break;
692 }
693 }
694 ret = 1;
695 out:
696 sysctl_head_finish(head);
697 return ret;
698 }
699
700 static int proc_sys_permission(struct inode *inode, int mask)
701 {
702 /*
703 * sysctl entries that are not writeable,
704 * are _NOT_ writeable, capabilities or not.
705 */
706 struct ctl_table_header *head;
707 struct ctl_table *table;
708 int error;
709
710 /* Executable files are not allowed under /proc/sys/ */
711 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
712 return -EACCES;
713
714 head = grab_header(inode);
715 if (IS_ERR(head))
716 return PTR_ERR(head);
717
718 table = PROC_I(inode)->sysctl_entry;
719 if (!table) /* global root - r-xr-xr-x */
720 error = mask & MAY_WRITE ? -EACCES : 0;
721 else /* Use the permissions on the sysctl table entry */
722 error = sysctl_perm(head->root, table, mask & ~MAY_NOT_BLOCK);
723
724 sysctl_head_finish(head);
725 return error;
726 }
727
728 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
729 {
730 struct inode *inode = dentry->d_inode;
731 int error;
732
733 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
734 return -EPERM;
735
736 error = inode_change_ok(inode, attr);
737 if (error)
738 return error;
739
740 if ((attr->ia_valid & ATTR_SIZE) &&
741 attr->ia_size != i_size_read(inode)) {
742 error = vmtruncate(inode, attr->ia_size);
743 if (error)
744 return error;
745 }
746
747 setattr_copy(inode, attr);
748 mark_inode_dirty(inode);
749 return 0;
750 }
751
752 static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
753 {
754 struct inode *inode = dentry->d_inode;
755 struct ctl_table_header *head = grab_header(inode);
756 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
757
758 if (IS_ERR(head))
759 return PTR_ERR(head);
760
761 generic_fillattr(inode, stat);
762 if (table)
763 stat->mode = (stat->mode & S_IFMT) | table->mode;
764
765 sysctl_head_finish(head);
766 return 0;
767 }
768
769 static const struct file_operations proc_sys_file_operations = {
770 .open = proc_sys_open,
771 .poll = proc_sys_poll,
772 .read = proc_sys_read,
773 .write = proc_sys_write,
774 .llseek = default_llseek,
775 };
776
777 static const struct file_operations proc_sys_dir_file_operations = {
778 .read = generic_read_dir,
779 .readdir = proc_sys_readdir,
780 .llseek = generic_file_llseek,
781 };
782
783 static const struct inode_operations proc_sys_inode_operations = {
784 .permission = proc_sys_permission,
785 .setattr = proc_sys_setattr,
786 .getattr = proc_sys_getattr,
787 };
788
789 static const struct inode_operations proc_sys_dir_operations = {
790 .lookup = proc_sys_lookup,
791 .permission = proc_sys_permission,
792 .setattr = proc_sys_setattr,
793 .getattr = proc_sys_getattr,
794 };
795
796 static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
797 {
798 if (flags & LOOKUP_RCU)
799 return -ECHILD;
800 return !PROC_I(dentry->d_inode)->sysctl->unregistering;
801 }
802
803 static int proc_sys_delete(const struct dentry *dentry)
804 {
805 return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
806 }
807
808 static int sysctl_is_seen(struct ctl_table_header *p)
809 {
810 struct ctl_table_set *set = p->set;
811 int res;
812 spin_lock(&sysctl_lock);
813 if (p->unregistering)
814 res = 0;
815 else if (!set->is_seen)
816 res = 1;
817 else
818 res = set->is_seen(set);
819 spin_unlock(&sysctl_lock);
820 return res;
821 }
822
823 static int proc_sys_compare(const struct dentry *parent,
824 const struct inode *pinode,
825 const struct dentry *dentry, const struct inode *inode,
826 unsigned int len, const char *str, const struct qstr *name)
827 {
828 struct ctl_table_header *head;
829 /* Although proc doesn't have negative dentries, rcu-walk means
830 * that inode here can be NULL */
831 /* AV: can it, indeed? */
832 if (!inode)
833 return 1;
834 if (name->len != len)
835 return 1;
836 if (memcmp(name->name, str, len))
837 return 1;
838 head = rcu_dereference(PROC_I(inode)->sysctl);
839 return !head || !sysctl_is_seen(head);
840 }
841
842 static const struct dentry_operations proc_sys_dentry_operations = {
843 .d_revalidate = proc_sys_revalidate,
844 .d_delete = proc_sys_delete,
845 .d_compare = proc_sys_compare,
846 };
847
848 static struct ctl_dir *find_subdir(struct ctl_dir *dir,
849 const char *name, int namelen)
850 {
851 struct ctl_table_header *head;
852 struct ctl_table *entry;
853
854 entry = find_entry(&head, dir, name, namelen);
855 if (!entry)
856 return ERR_PTR(-ENOENT);
857 if (!S_ISDIR(entry->mode))
858 return ERR_PTR(-ENOTDIR);
859 return container_of(head, struct ctl_dir, header);
860 }
861
862 static struct ctl_dir *new_dir(struct ctl_table_set *set,
863 const char *name, int namelen)
864 {
865 struct ctl_table *table;
866 struct ctl_dir *new;
867 struct ctl_node *node;
868 char *new_name;
869
870 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
871 sizeof(struct ctl_table)*2 + namelen + 1,
872 GFP_KERNEL);
873 if (!new)
874 return NULL;
875
876 node = (struct ctl_node *)(new + 1);
877 table = (struct ctl_table *)(node + 1);
878 new_name = (char *)(table + 2);
879 memcpy(new_name, name, namelen);
880 new_name[namelen] = '\0';
881 table[0].procname = new_name;
882 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
883 init_header(&new->header, set->dir.header.root, set, node, table);
884
885 return new;
886 }
887
888 /**
889 * get_subdir - find or create a subdir with the specified name.
890 * @dir: Directory to create the subdirectory in
891 * @name: The name of the subdirectory to find or create
892 * @namelen: The length of name
893 *
894 * Takes a directory with an elevated reference count so we know that
895 * if we drop the lock the directory will not go away. Upon success
896 * the reference is moved from @dir to the returned subdirectory.
897 * Upon error an error code is returned and the reference on @dir is
898 * simply dropped.
899 */
900 static struct ctl_dir *get_subdir(struct ctl_dir *dir,
901 const char *name, int namelen)
902 {
903 struct ctl_table_set *set = dir->header.set;
904 struct ctl_dir *subdir, *new = NULL;
905 int err;
906
907 spin_lock(&sysctl_lock);
908 subdir = find_subdir(dir, name, namelen);
909 if (!IS_ERR(subdir))
910 goto found;
911 if (PTR_ERR(subdir) != -ENOENT)
912 goto failed;
913
914 spin_unlock(&sysctl_lock);
915 new = new_dir(set, name, namelen);
916 spin_lock(&sysctl_lock);
917 subdir = ERR_PTR(-ENOMEM);
918 if (!new)
919 goto failed;
920
921 /* Was the subdir added while we dropped the lock? */
922 subdir = find_subdir(dir, name, namelen);
923 if (!IS_ERR(subdir))
924 goto found;
925 if (PTR_ERR(subdir) != -ENOENT)
926 goto failed;
927
928 /* Nope. Use the our freshly made directory entry. */
929 err = insert_header(dir, &new->header);
930 subdir = ERR_PTR(err);
931 if (err)
932 goto failed;
933 subdir = new;
934 found:
935 subdir->header.nreg++;
936 failed:
937 if (unlikely(IS_ERR(subdir))) {
938 printk(KERN_ERR "sysctl could not get directory: ");
939 sysctl_print_dir(dir);
940 printk(KERN_CONT "/%*.*s %ld\n",
941 namelen, namelen, name, PTR_ERR(subdir));
942 }
943 drop_sysctl_table(&dir->header);
944 if (new)
945 drop_sysctl_table(&new->header);
946 spin_unlock(&sysctl_lock);
947 return subdir;
948 }
949
950 static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
951 {
952 struct ctl_dir *parent;
953 const char *procname;
954 if (!dir->header.parent)
955 return &set->dir;
956 parent = xlate_dir(set, dir->header.parent);
957 if (IS_ERR(parent))
958 return parent;
959 procname = dir->header.ctl_table[0].procname;
960 return find_subdir(parent, procname, strlen(procname));
961 }
962
963 static int sysctl_follow_link(struct ctl_table_header **phead,
964 struct ctl_table **pentry, struct nsproxy *namespaces)
965 {
966 struct ctl_table_header *head;
967 struct ctl_table_root *root;
968 struct ctl_table_set *set;
969 struct ctl_table *entry;
970 struct ctl_dir *dir;
971 int ret;
972
973 ret = 0;
974 spin_lock(&sysctl_lock);
975 root = (*pentry)->data;
976 set = lookup_header_set(root, namespaces);
977 dir = xlate_dir(set, (*phead)->parent);
978 if (IS_ERR(dir))
979 ret = PTR_ERR(dir);
980 else {
981 const char *procname = (*pentry)->procname;
982 head = NULL;
983 entry = find_entry(&head, dir, procname, strlen(procname));
984 ret = -ENOENT;
985 if (entry && use_table(head)) {
986 unuse_table(*phead);
987 *phead = head;
988 *pentry = entry;
989 ret = 0;
990 }
991 }
992
993 spin_unlock(&sysctl_lock);
994 return ret;
995 }
996
997 static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
998 {
999 struct va_format vaf;
1000 va_list args;
1001
1002 va_start(args, fmt);
1003 vaf.fmt = fmt;
1004 vaf.va = &args;
1005
1006 printk(KERN_ERR "sysctl table check failed: %s/%s %pV\n",
1007 path, table->procname, &vaf);
1008
1009 va_end(args);
1010 return -EINVAL;
1011 }
1012
1013 static int sysctl_check_table(const char *path, struct ctl_table *table)
1014 {
1015 int err = 0;
1016 for (; table->procname; table++) {
1017 if (table->child)
1018 err = sysctl_err(path, table, "Not a file");
1019
1020 if ((table->proc_handler == proc_dostring) ||
1021 (table->proc_handler == proc_dointvec) ||
1022 (table->proc_handler == proc_dointvec_minmax) ||
1023 (table->proc_handler == proc_dointvec_jiffies) ||
1024 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1025 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1026 (table->proc_handler == proc_doulongvec_minmax) ||
1027 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1028 if (!table->data)
1029 err = sysctl_err(path, table, "No data");
1030 if (!table->maxlen)
1031 err = sysctl_err(path, table, "No maxlen");
1032 }
1033 if (!table->proc_handler)
1034 err = sysctl_err(path, table, "No proc_handler");
1035
1036 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1037 err = sysctl_err(path, table, "bogus .mode 0%o",
1038 table->mode);
1039 }
1040 return err;
1041 }
1042
1043 static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1044 struct ctl_table_root *link_root)
1045 {
1046 struct ctl_table *link_table, *entry, *link;
1047 struct ctl_table_header *links;
1048 struct ctl_node *node;
1049 char *link_name;
1050 int nr_entries, name_bytes;
1051
1052 name_bytes = 0;
1053 nr_entries = 0;
1054 for (entry = table; entry->procname; entry++) {
1055 nr_entries++;
1056 name_bytes += strlen(entry->procname) + 1;
1057 }
1058
1059 links = kzalloc(sizeof(struct ctl_table_header) +
1060 sizeof(struct ctl_node)*nr_entries +
1061 sizeof(struct ctl_table)*(nr_entries + 1) +
1062 name_bytes,
1063 GFP_KERNEL);
1064
1065 if (!links)
1066 return NULL;
1067
1068 node = (struct ctl_node *)(links + 1);
1069 link_table = (struct ctl_table *)(node + nr_entries);
1070 link_name = (char *)&link_table[nr_entries + 1];
1071
1072 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1073 int len = strlen(entry->procname) + 1;
1074 memcpy(link_name, entry->procname, len);
1075 link->procname = link_name;
1076 link->mode = S_IFLNK|S_IRWXUGO;
1077 link->data = link_root;
1078 link_name += len;
1079 }
1080 init_header(links, dir->header.root, dir->header.set, node, link_table);
1081 links->nreg = nr_entries;
1082
1083 return links;
1084 }
1085
1086 static bool get_links(struct ctl_dir *dir,
1087 struct ctl_table *table, struct ctl_table_root *link_root)
1088 {
1089 struct ctl_table_header *head;
1090 struct ctl_table *entry, *link;
1091
1092 /* Are there links available for every entry in table? */
1093 for (entry = table; entry->procname; entry++) {
1094 const char *procname = entry->procname;
1095 link = find_entry(&head, dir, procname, strlen(procname));
1096 if (!link)
1097 return false;
1098 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1099 continue;
1100 if (S_ISLNK(link->mode) && (link->data == link_root))
1101 continue;
1102 return false;
1103 }
1104
1105 /* The checks passed. Increase the registration count on the links */
1106 for (entry = table; entry->procname; entry++) {
1107 const char *procname = entry->procname;
1108 link = find_entry(&head, dir, procname, strlen(procname));
1109 head->nreg++;
1110 }
1111 return true;
1112 }
1113
1114 static int insert_links(struct ctl_table_header *head)
1115 {
1116 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1117 struct ctl_dir *core_parent = NULL;
1118 struct ctl_table_header *links;
1119 int err;
1120
1121 if (head->set == root_set)
1122 return 0;
1123
1124 core_parent = xlate_dir(root_set, head->parent);
1125 if (IS_ERR(core_parent))
1126 return 0;
1127
1128 if (get_links(core_parent, head->ctl_table, head->root))
1129 return 0;
1130
1131 core_parent->header.nreg++;
1132 spin_unlock(&sysctl_lock);
1133
1134 links = new_links(core_parent, head->ctl_table, head->root);
1135
1136 spin_lock(&sysctl_lock);
1137 err = -ENOMEM;
1138 if (!links)
1139 goto out;
1140
1141 err = 0;
1142 if (get_links(core_parent, head->ctl_table, head->root)) {
1143 kfree(links);
1144 goto out;
1145 }
1146
1147 err = insert_header(core_parent, links);
1148 if (err)
1149 kfree(links);
1150 out:
1151 drop_sysctl_table(&core_parent->header);
1152 return err;
1153 }
1154
1155 /**
1156 * __register_sysctl_table - register a leaf sysctl table
1157 * @set: Sysctl tree to register on
1158 * @path: The path to the directory the sysctl table is in.
1159 * @table: the top-level table structure
1160 *
1161 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1162 * array. A completely 0 filled entry terminates the table.
1163 *
1164 * The members of the &struct ctl_table structure are used as follows:
1165 *
1166 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1167 * enter a sysctl file
1168 *
1169 * data - a pointer to data for use by proc_handler
1170 *
1171 * maxlen - the maximum size in bytes of the data
1172 *
1173 * mode - the file permissions for the /proc/sys file
1174 *
1175 * child - must be %NULL.
1176 *
1177 * proc_handler - the text handler routine (described below)
1178 *
1179 * extra1, extra2 - extra pointers usable by the proc handler routines
1180 *
1181 * Leaf nodes in the sysctl tree will be represented by a single file
1182 * under /proc; non-leaf nodes will be represented by directories.
1183 *
1184 * There must be a proc_handler routine for any terminal nodes.
1185 * Several default handlers are available to cover common cases -
1186 *
1187 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1188 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1189 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1190 *
1191 * It is the handler's job to read the input buffer from user memory
1192 * and process it. The handler should return 0 on success.
1193 *
1194 * This routine returns %NULL on a failure to register, and a pointer
1195 * to the table header on success.
1196 */
1197 struct ctl_table_header *__register_sysctl_table(
1198 struct ctl_table_set *set,
1199 const char *path, struct ctl_table *table)
1200 {
1201 struct ctl_table_root *root = set->dir.header.root;
1202 struct ctl_table_header *header;
1203 const char *name, *nextname;
1204 struct ctl_dir *dir;
1205 struct ctl_table *entry;
1206 struct ctl_node *node;
1207 int nr_entries = 0;
1208
1209 for (entry = table; entry->procname; entry++)
1210 nr_entries++;
1211
1212 header = kzalloc(sizeof(struct ctl_table_header) +
1213 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1214 if (!header)
1215 return NULL;
1216
1217 node = (struct ctl_node *)(header + 1);
1218 init_header(header, root, set, node, table);
1219 if (sysctl_check_table(path, table))
1220 goto fail;
1221
1222 spin_lock(&sysctl_lock);
1223 dir = &set->dir;
1224 /* Reference moved down the diretory tree get_subdir */
1225 dir->header.nreg++;
1226 spin_unlock(&sysctl_lock);
1227
1228 /* Find the directory for the ctl_table */
1229 for (name = path; name; name = nextname) {
1230 int namelen;
1231 nextname = strchr(name, '/');
1232 if (nextname) {
1233 namelen = nextname - name;
1234 nextname++;
1235 } else {
1236 namelen = strlen(name);
1237 }
1238 if (namelen == 0)
1239 continue;
1240
1241 dir = get_subdir(dir, name, namelen);
1242 if (IS_ERR(dir))
1243 goto fail;
1244 }
1245
1246 spin_lock(&sysctl_lock);
1247 if (insert_header(dir, header))
1248 goto fail_put_dir_locked;
1249
1250 drop_sysctl_table(&dir->header);
1251 spin_unlock(&sysctl_lock);
1252
1253 return header;
1254
1255 fail_put_dir_locked:
1256 drop_sysctl_table(&dir->header);
1257 spin_unlock(&sysctl_lock);
1258 fail:
1259 kfree(header);
1260 dump_stack();
1261 return NULL;
1262 }
1263
1264 /**
1265 * register_sysctl - register a sysctl table
1266 * @path: The path to the directory the sysctl table is in.
1267 * @table: the table structure
1268 *
1269 * Register a sysctl table. @table should be a filled in ctl_table
1270 * array. A completely 0 filled entry terminates the table.
1271 *
1272 * See __register_sysctl_table for more details.
1273 */
1274 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1275 {
1276 return __register_sysctl_table(&sysctl_table_root.default_set,
1277 path, table);
1278 }
1279 EXPORT_SYMBOL(register_sysctl);
1280
1281 static char *append_path(const char *path, char *pos, const char *name)
1282 {
1283 int namelen;
1284 namelen = strlen(name);
1285 if (((pos - path) + namelen + 2) >= PATH_MAX)
1286 return NULL;
1287 memcpy(pos, name, namelen);
1288 pos[namelen] = '/';
1289 pos[namelen + 1] = '\0';
1290 pos += namelen + 1;
1291 return pos;
1292 }
1293
1294 static int count_subheaders(struct ctl_table *table)
1295 {
1296 int has_files = 0;
1297 int nr_subheaders = 0;
1298 struct ctl_table *entry;
1299
1300 /* special case: no directory and empty directory */
1301 if (!table || !table->procname)
1302 return 1;
1303
1304 for (entry = table; entry->procname; entry++) {
1305 if (entry->child)
1306 nr_subheaders += count_subheaders(entry->child);
1307 else
1308 has_files = 1;
1309 }
1310 return nr_subheaders + has_files;
1311 }
1312
1313 static int register_leaf_sysctl_tables(const char *path, char *pos,
1314 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1315 struct ctl_table *table)
1316 {
1317 struct ctl_table *ctl_table_arg = NULL;
1318 struct ctl_table *entry, *files;
1319 int nr_files = 0;
1320 int nr_dirs = 0;
1321 int err = -ENOMEM;
1322
1323 for (entry = table; entry->procname; entry++) {
1324 if (entry->child)
1325 nr_dirs++;
1326 else
1327 nr_files++;
1328 }
1329
1330 files = table;
1331 /* If there are mixed files and directories we need a new table */
1332 if (nr_dirs && nr_files) {
1333 struct ctl_table *new;
1334 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1335 GFP_KERNEL);
1336 if (!files)
1337 goto out;
1338
1339 ctl_table_arg = files;
1340 for (new = files, entry = table; entry->procname; entry++) {
1341 if (entry->child)
1342 continue;
1343 *new = *entry;
1344 new++;
1345 }
1346 }
1347
1348 /* Register everything except a directory full of subdirectories */
1349 if (nr_files || !nr_dirs) {
1350 struct ctl_table_header *header;
1351 header = __register_sysctl_table(set, path, files);
1352 if (!header) {
1353 kfree(ctl_table_arg);
1354 goto out;
1355 }
1356
1357 /* Remember if we need to free the file table */
1358 header->ctl_table_arg = ctl_table_arg;
1359 **subheader = header;
1360 (*subheader)++;
1361 }
1362
1363 /* Recurse into the subdirectories. */
1364 for (entry = table; entry->procname; entry++) {
1365 char *child_pos;
1366
1367 if (!entry->child)
1368 continue;
1369
1370 err = -ENAMETOOLONG;
1371 child_pos = append_path(path, pos, entry->procname);
1372 if (!child_pos)
1373 goto out;
1374
1375 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1376 set, entry->child);
1377 pos[0] = '\0';
1378 if (err)
1379 goto out;
1380 }
1381 err = 0;
1382 out:
1383 /* On failure our caller will unregister all registered subheaders */
1384 return err;
1385 }
1386
1387 /**
1388 * __register_sysctl_paths - register a sysctl table hierarchy
1389 * @set: Sysctl tree to register on
1390 * @path: The path to the directory the sysctl table is in.
1391 * @table: the top-level table structure
1392 *
1393 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1394 * array. A completely 0 filled entry terminates the table.
1395 *
1396 * See __register_sysctl_table for more details.
1397 */
1398 struct ctl_table_header *__register_sysctl_paths(
1399 struct ctl_table_set *set,
1400 const struct ctl_path *path, struct ctl_table *table)
1401 {
1402 struct ctl_table *ctl_table_arg = table;
1403 int nr_subheaders = count_subheaders(table);
1404 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1405 const struct ctl_path *component;
1406 char *new_path, *pos;
1407
1408 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1409 if (!new_path)
1410 return NULL;
1411
1412 pos[0] = '\0';
1413 for (component = path; component->procname; component++) {
1414 pos = append_path(new_path, pos, component->procname);
1415 if (!pos)
1416 goto out;
1417 }
1418 while (table->procname && table->child && !table[1].procname) {
1419 pos = append_path(new_path, pos, table->procname);
1420 if (!pos)
1421 goto out;
1422 table = table->child;
1423 }
1424 if (nr_subheaders == 1) {
1425 header = __register_sysctl_table(set, new_path, table);
1426 if (header)
1427 header->ctl_table_arg = ctl_table_arg;
1428 } else {
1429 header = kzalloc(sizeof(*header) +
1430 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1431 if (!header)
1432 goto out;
1433
1434 subheaders = (struct ctl_table_header **) (header + 1);
1435 subheader = subheaders;
1436 header->ctl_table_arg = ctl_table_arg;
1437
1438 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1439 set, table))
1440 goto err_register_leaves;
1441 }
1442
1443 out:
1444 kfree(new_path);
1445 return header;
1446
1447 err_register_leaves:
1448 while (subheader > subheaders) {
1449 struct ctl_table_header *subh = *(--subheader);
1450 struct ctl_table *table = subh->ctl_table_arg;
1451 unregister_sysctl_table(subh);
1452 kfree(table);
1453 }
1454 kfree(header);
1455 header = NULL;
1456 goto out;
1457 }
1458
1459 /**
1460 * register_sysctl_table_path - register a sysctl table hierarchy
1461 * @path: The path to the directory the sysctl table is in.
1462 * @table: the top-level table structure
1463 *
1464 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1465 * array. A completely 0 filled entry terminates the table.
1466 *
1467 * See __register_sysctl_paths for more details.
1468 */
1469 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1470 struct ctl_table *table)
1471 {
1472 return __register_sysctl_paths(&sysctl_table_root.default_set,
1473 path, table);
1474 }
1475 EXPORT_SYMBOL(register_sysctl_paths);
1476
1477 /**
1478 * register_sysctl_table - register a sysctl table hierarchy
1479 * @table: the top-level table structure
1480 *
1481 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1482 * array. A completely 0 filled entry terminates the table.
1483 *
1484 * See register_sysctl_paths for more details.
1485 */
1486 struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1487 {
1488 static const struct ctl_path null_path[] = { {} };
1489
1490 return register_sysctl_paths(null_path, table);
1491 }
1492 EXPORT_SYMBOL(register_sysctl_table);
1493
1494 static void put_links(struct ctl_table_header *header)
1495 {
1496 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1497 struct ctl_table_root *root = header->root;
1498 struct ctl_dir *parent = header->parent;
1499 struct ctl_dir *core_parent;
1500 struct ctl_table *entry;
1501
1502 if (header->set == root_set)
1503 return;
1504
1505 core_parent = xlate_dir(root_set, parent);
1506 if (IS_ERR(core_parent))
1507 return;
1508
1509 for (entry = header->ctl_table; entry->procname; entry++) {
1510 struct ctl_table_header *link_head;
1511 struct ctl_table *link;
1512 const char *name = entry->procname;
1513
1514 link = find_entry(&link_head, core_parent, name, strlen(name));
1515 if (link &&
1516 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1517 (S_ISLNK(link->mode) && (link->data == root)))) {
1518 drop_sysctl_table(link_head);
1519 }
1520 else {
1521 printk(KERN_ERR "sysctl link missing during unregister: ");
1522 sysctl_print_dir(parent);
1523 printk(KERN_CONT "/%s\n", name);
1524 }
1525 }
1526 }
1527
1528 static void drop_sysctl_table(struct ctl_table_header *header)
1529 {
1530 struct ctl_dir *parent = header->parent;
1531
1532 if (--header->nreg)
1533 return;
1534
1535 put_links(header);
1536 start_unregistering(header);
1537 if (!--header->count)
1538 kfree_rcu(header, rcu);
1539
1540 if (parent)
1541 drop_sysctl_table(&parent->header);
1542 }
1543
1544 /**
1545 * unregister_sysctl_table - unregister a sysctl table hierarchy
1546 * @header: the header returned from register_sysctl_table
1547 *
1548 * Unregisters the sysctl table and all children. proc entries may not
1549 * actually be removed until they are no longer used by anyone.
1550 */
1551 void unregister_sysctl_table(struct ctl_table_header * header)
1552 {
1553 int nr_subheaders;
1554 might_sleep();
1555
1556 if (header == NULL)
1557 return;
1558
1559 nr_subheaders = count_subheaders(header->ctl_table_arg);
1560 if (unlikely(nr_subheaders > 1)) {
1561 struct ctl_table_header **subheaders;
1562 int i;
1563
1564 subheaders = (struct ctl_table_header **)(header + 1);
1565 for (i = nr_subheaders -1; i >= 0; i--) {
1566 struct ctl_table_header *subh = subheaders[i];
1567 struct ctl_table *table = subh->ctl_table_arg;
1568 unregister_sysctl_table(subh);
1569 kfree(table);
1570 }
1571 kfree(header);
1572 return;
1573 }
1574
1575 spin_lock(&sysctl_lock);
1576 drop_sysctl_table(header);
1577 spin_unlock(&sysctl_lock);
1578 }
1579 EXPORT_SYMBOL(unregister_sysctl_table);
1580
1581 void setup_sysctl_set(struct ctl_table_set *set,
1582 struct ctl_table_root *root,
1583 int (*is_seen)(struct ctl_table_set *))
1584 {
1585 memset(set, 0, sizeof(*set));
1586 set->is_seen = is_seen;
1587 init_header(&set->dir.header, root, set, NULL, root_table);
1588 }
1589
1590 void retire_sysctl_set(struct ctl_table_set *set)
1591 {
1592 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1593 }
1594
1595 int __init proc_sys_init(void)
1596 {
1597 struct proc_dir_entry *proc_sys_root;
1598
1599 proc_sys_root = proc_mkdir("sys", NULL);
1600 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1601 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1602 proc_sys_root->nlink = 0;
1603
1604 return sysctl_init();
1605 }
Linux kernel - Deliverables
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