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[readdir] convert procfs
[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/printk.h>
9 #include <linux/security.h>
10 #include <linux/sched.h>
11 #include <linux/namei.h>
12 #include <linux/mm.h>
13 #include <linux/module.h>
14 #include "internal.h"
15
16 static const struct dentry_operations proc_sys_dentry_operations;
17 static const struct file_operations proc_sys_file_operations;
18 static const struct inode_operations proc_sys_inode_operations;
19 static const struct file_operations proc_sys_dir_file_operations;
20 static const struct inode_operations proc_sys_dir_operations;
21
22 void proc_sys_poll_notify(struct ctl_table_poll *poll)
23 {
24 if (!poll)
25 return;
26
27 atomic_inc(&poll->event);
28 wake_up_interruptible(&poll->wait);
29 }
30
31 static struct ctl_table root_table[] = {
32 {
33 .procname = "",
34 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
35 },
36 { }
37 };
38 static struct ctl_table_root sysctl_table_root = {
39 .default_set.dir.header = {
40 {{.count = 1,
41 .nreg = 1,
42 .ctl_table = root_table }},
43 .ctl_table_arg = root_table,
44 .root = &sysctl_table_root,
45 .set = &sysctl_table_root.default_set,
46 },
47 };
48
49 static DEFINE_SPINLOCK(sysctl_lock);
50
51 static void drop_sysctl_table(struct ctl_table_header *header);
52 static int sysctl_follow_link(struct ctl_table_header **phead,
53 struct ctl_table **pentry, struct nsproxy *namespaces);
54 static int insert_links(struct ctl_table_header *head);
55 static void put_links(struct ctl_table_header *header);
56
57 static void sysctl_print_dir(struct ctl_dir *dir)
58 {
59 if (dir->header.parent)
60 sysctl_print_dir(dir->header.parent);
61 pr_cont("%s/", dir->header.ctl_table[0].procname);
62 }
63
64 static int namecmp(const char *name1, int len1, const char *name2, int len2)
65 {
66 int minlen;
67 int cmp;
68
69 minlen = len1;
70 if (minlen > len2)
71 minlen = len2;
72
73 cmp = memcmp(name1, name2, minlen);
74 if (cmp == 0)
75 cmp = len1 - len2;
76 return cmp;
77 }
78
79 /* Called under sysctl_lock */
80 static struct ctl_table *find_entry(struct ctl_table_header **phead,
81 struct ctl_dir *dir, const char *name, int namelen)
82 {
83 struct ctl_table_header *head;
84 struct ctl_table *entry;
85 struct rb_node *node = dir->root.rb_node;
86
87 while (node)
88 {
89 struct ctl_node *ctl_node;
90 const char *procname;
91 int cmp;
92
93 ctl_node = rb_entry(node, struct ctl_node, node);
94 head = ctl_node->header;
95 entry = &head->ctl_table[ctl_node - head->node];
96 procname = entry->procname;
97
98 cmp = namecmp(name, namelen, procname, strlen(procname));
99 if (cmp < 0)
100 node = node->rb_left;
101 else if (cmp > 0)
102 node = node->rb_right;
103 else {
104 *phead = head;
105 return entry;
106 }
107 }
108 return NULL;
109 }
110
111 static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
112 {
113 struct rb_node *node = &head->node[entry - head->ctl_table].node;
114 struct rb_node **p = &head->parent->root.rb_node;
115 struct rb_node *parent = NULL;
116 const char *name = entry->procname;
117 int namelen = strlen(name);
118
119 while (*p) {
120 struct ctl_table_header *parent_head;
121 struct ctl_table *parent_entry;
122 struct ctl_node *parent_node;
123 const char *parent_name;
124 int cmp;
125
126 parent = *p;
127 parent_node = rb_entry(parent, struct ctl_node, node);
128 parent_head = parent_node->header;
129 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
130 parent_name = parent_entry->procname;
131
132 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
133 if (cmp < 0)
134 p = &(*p)->rb_left;
135 else if (cmp > 0)
136 p = &(*p)->rb_right;
137 else {
138 pr_err("sysctl duplicate entry: ");
139 sysctl_print_dir(head->parent);
140 pr_cont("/%s\n", entry->procname);
141 return -EEXIST;
142 }
143 }
144
145 rb_link_node(node, parent, p);
146 rb_insert_color(node, &head->parent->root);
147 return 0;
148 }
149
150 static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
151 {
152 struct rb_node *node = &head->node[entry - head->ctl_table].node;
153
154 rb_erase(node, &head->parent->root);
155 }
156
157 static void init_header(struct ctl_table_header *head,
158 struct ctl_table_root *root, struct ctl_table_set *set,
159 struct ctl_node *node, struct ctl_table *table)
160 {
161 head->ctl_table = table;
162 head->ctl_table_arg = table;
163 head->used = 0;
164 head->count = 1;
165 head->nreg = 1;
166 head->unregistering = NULL;
167 head->root = root;
168 head->set = set;
169 head->parent = NULL;
170 head->node = node;
171 if (node) {
172 struct ctl_table *entry;
173 for (entry = table; entry->procname; entry++, node++)
174 node->header = head;
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 BUG_ON(!head);
270 spin_lock(&sysctl_lock);
271 if (!use_table(head))
272 head = ERR_PTR(-ENOENT);
273 spin_unlock(&sysctl_lock);
274 return head;
275 }
276
277 static void sysctl_head_finish(struct ctl_table_header *head)
278 {
279 if (!head)
280 return;
281 spin_lock(&sysctl_lock);
282 unuse_table(head);
283 spin_unlock(&sysctl_lock);
284 }
285
286 static struct ctl_table_set *
287 lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces)
288 {
289 struct ctl_table_set *set = &root->default_set;
290 if (root->lookup)
291 set = root->lookup(root, namespaces);
292 return set;
293 }
294
295 static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
296 struct ctl_dir *dir,
297 const char *name, int namelen)
298 {
299 struct ctl_table_header *head;
300 struct ctl_table *entry;
301
302 spin_lock(&sysctl_lock);
303 entry = find_entry(&head, dir, name, namelen);
304 if (entry && use_table(head))
305 *phead = head;
306 else
307 entry = NULL;
308 spin_unlock(&sysctl_lock);
309 return entry;
310 }
311
312 static struct ctl_node *first_usable_entry(struct rb_node *node)
313 {
314 struct ctl_node *ctl_node;
315
316 for (;node; node = rb_next(node)) {
317 ctl_node = rb_entry(node, struct ctl_node, node);
318 if (use_table(ctl_node->header))
319 return ctl_node;
320 }
321 return NULL;
322 }
323
324 static void first_entry(struct ctl_dir *dir,
325 struct ctl_table_header **phead, struct ctl_table **pentry)
326 {
327 struct ctl_table_header *head = NULL;
328 struct ctl_table *entry = NULL;
329 struct ctl_node *ctl_node;
330
331 spin_lock(&sysctl_lock);
332 ctl_node = first_usable_entry(rb_first(&dir->root));
333 spin_unlock(&sysctl_lock);
334 if (ctl_node) {
335 head = ctl_node->header;
336 entry = &head->ctl_table[ctl_node - head->node];
337 }
338 *phead = head;
339 *pentry = entry;
340 }
341
342 static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
343 {
344 struct ctl_table_header *head = *phead;
345 struct ctl_table *entry = *pentry;
346 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
347
348 spin_lock(&sysctl_lock);
349 unuse_table(head);
350
351 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
352 spin_unlock(&sysctl_lock);
353 head = NULL;
354 if (ctl_node) {
355 head = ctl_node->header;
356 entry = &head->ctl_table[ctl_node - head->node];
357 }
358 *phead = head;
359 *pentry = entry;
360 }
361
362 void register_sysctl_root(struct ctl_table_root *root)
363 {
364 }
365
366 /*
367 * sysctl_perm does NOT grant the superuser all rights automatically, because
368 * some sysctl variables are readonly even to root.
369 */
370
371 static int test_perm(int mode, int op)
372 {
373 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
374 mode >>= 6;
375 else if (in_egroup_p(GLOBAL_ROOT_GID))
376 mode >>= 3;
377 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
378 return 0;
379 return -EACCES;
380 }
381
382 static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
383 {
384 struct ctl_table_root *root = head->root;
385 int mode;
386
387 if (root->permissions)
388 mode = root->permissions(head, 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 = file_inode(filp);
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, 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 = file_inode(filp);
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 bool proc_sys_fill_cache(struct file *file,
577 struct dir_context *ctx,
578 struct ctl_table_header *head,
579 struct ctl_table *table)
580 {
581 struct dentry *child, *dir = file->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 false;
599 } else {
600 d_set_d_op(child, &proc_sys_dentry_operations);
601 d_add(child, inode);
602 }
603 } else {
604 return false;
605 }
606 }
607 inode = child->d_inode;
608 ino = inode->i_ino;
609 type = inode->i_mode >> 12;
610 dput(child);
611 return dir_emit(ctx, qname.name, qname.len, ino, type);
612 }
613
614 static bool proc_sys_link_fill_cache(struct file *file,
615 struct dir_context *ctx,
616 struct ctl_table_header *head,
617 struct ctl_table *table)
618 {
619 bool ret = true;
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 int err = sysctl_follow_link(&head, &table, current->nsproxy);
625 if (err)
626 goto out;
627 }
628
629 ret = proc_sys_fill_cache(file, ctx, 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 struct dir_context *ctx)
638 {
639 bool res;
640
641 if ((*pos)++ < ctx->pos)
642 return true;
643
644 if (unlikely(S_ISLNK(table->mode)))
645 res = proc_sys_link_fill_cache(file, ctx, head, table);
646 else
647 res = proc_sys_fill_cache(file, ctx, head, table);
648
649 if (res)
650 ctx->pos = *pos;
651
652 return res;
653 }
654
655 static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
656 {
657 struct ctl_table_header *head = grab_header(file_inode(file));
658 struct ctl_table_header *h = NULL;
659 struct ctl_table *entry;
660 struct ctl_dir *ctl_dir;
661 unsigned long pos;
662
663 if (IS_ERR(head))
664 return PTR_ERR(head);
665
666 ctl_dir = container_of(head, struct ctl_dir, header);
667
668 if (!dir_emit_dots(file, ctx))
669 return 0;
670
671 pos = 2;
672
673 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
674 if (!scan(h, entry, &pos, file, ctx)) {
675 sysctl_head_finish(h);
676 break;
677 }
678 }
679 sysctl_head_finish(head);
680 return 0;
681 }
682
683 static int proc_sys_permission(struct inode *inode, int mask)
684 {
685 /*
686 * sysctl entries that are not writeable,
687 * are _NOT_ writeable, capabilities or not.
688 */
689 struct ctl_table_header *head;
690 struct ctl_table *table;
691 int error;
692
693 /* Executable files are not allowed under /proc/sys/ */
694 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
695 return -EACCES;
696
697 head = grab_header(inode);
698 if (IS_ERR(head))
699 return PTR_ERR(head);
700
701 table = PROC_I(inode)->sysctl_entry;
702 if (!table) /* global root - r-xr-xr-x */
703 error = mask & MAY_WRITE ? -EACCES : 0;
704 else /* Use the permissions on the sysctl table entry */
705 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
706
707 sysctl_head_finish(head);
708 return error;
709 }
710
711 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
712 {
713 struct inode *inode = dentry->d_inode;
714 int error;
715
716 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
717 return -EPERM;
718
719 error = inode_change_ok(inode, attr);
720 if (error)
721 return error;
722
723 setattr_copy(inode, attr);
724 mark_inode_dirty(inode);
725 return 0;
726 }
727
728 static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
729 {
730 struct inode *inode = dentry->d_inode;
731 struct ctl_table_header *head = grab_header(inode);
732 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
733
734 if (IS_ERR(head))
735 return PTR_ERR(head);
736
737 generic_fillattr(inode, stat);
738 if (table)
739 stat->mode = (stat->mode & S_IFMT) | table->mode;
740
741 sysctl_head_finish(head);
742 return 0;
743 }
744
745 static const struct file_operations proc_sys_file_operations = {
746 .open = proc_sys_open,
747 .poll = proc_sys_poll,
748 .read = proc_sys_read,
749 .write = proc_sys_write,
750 .llseek = default_llseek,
751 };
752
753 static const struct file_operations proc_sys_dir_file_operations = {
754 .read = generic_read_dir,
755 .iterate = proc_sys_readdir,
756 .llseek = generic_file_llseek,
757 };
758
759 static const struct inode_operations proc_sys_inode_operations = {
760 .permission = proc_sys_permission,
761 .setattr = proc_sys_setattr,
762 .getattr = proc_sys_getattr,
763 };
764
765 static const struct inode_operations proc_sys_dir_operations = {
766 .lookup = proc_sys_lookup,
767 .permission = proc_sys_permission,
768 .setattr = proc_sys_setattr,
769 .getattr = proc_sys_getattr,
770 };
771
772 static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
773 {
774 if (flags & LOOKUP_RCU)
775 return -ECHILD;
776 return !PROC_I(dentry->d_inode)->sysctl->unregistering;
777 }
778
779 static int proc_sys_delete(const struct dentry *dentry)
780 {
781 return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
782 }
783
784 static int sysctl_is_seen(struct ctl_table_header *p)
785 {
786 struct ctl_table_set *set = p->set;
787 int res;
788 spin_lock(&sysctl_lock);
789 if (p->unregistering)
790 res = 0;
791 else if (!set->is_seen)
792 res = 1;
793 else
794 res = set->is_seen(set);
795 spin_unlock(&sysctl_lock);
796 return res;
797 }
798
799 static int proc_sys_compare(const struct dentry *parent,
800 const struct inode *pinode,
801 const struct dentry *dentry, const struct inode *inode,
802 unsigned int len, const char *str, const struct qstr *name)
803 {
804 struct ctl_table_header *head;
805 /* Although proc doesn't have negative dentries, rcu-walk means
806 * that inode here can be NULL */
807 /* AV: can it, indeed? */
808 if (!inode)
809 return 1;
810 if (name->len != len)
811 return 1;
812 if (memcmp(name->name, str, len))
813 return 1;
814 head = rcu_dereference(PROC_I(inode)->sysctl);
815 return !head || !sysctl_is_seen(head);
816 }
817
818 static const struct dentry_operations proc_sys_dentry_operations = {
819 .d_revalidate = proc_sys_revalidate,
820 .d_delete = proc_sys_delete,
821 .d_compare = proc_sys_compare,
822 };
823
824 static struct ctl_dir *find_subdir(struct ctl_dir *dir,
825 const char *name, int namelen)
826 {
827 struct ctl_table_header *head;
828 struct ctl_table *entry;
829
830 entry = find_entry(&head, dir, name, namelen);
831 if (!entry)
832 return ERR_PTR(-ENOENT);
833 if (!S_ISDIR(entry->mode))
834 return ERR_PTR(-ENOTDIR);
835 return container_of(head, struct ctl_dir, header);
836 }
837
838 static struct ctl_dir *new_dir(struct ctl_table_set *set,
839 const char *name, int namelen)
840 {
841 struct ctl_table *table;
842 struct ctl_dir *new;
843 struct ctl_node *node;
844 char *new_name;
845
846 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
847 sizeof(struct ctl_table)*2 + namelen + 1,
848 GFP_KERNEL);
849 if (!new)
850 return NULL;
851
852 node = (struct ctl_node *)(new + 1);
853 table = (struct ctl_table *)(node + 1);
854 new_name = (char *)(table + 2);
855 memcpy(new_name, name, namelen);
856 new_name[namelen] = '\0';
857 table[0].procname = new_name;
858 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
859 init_header(&new->header, set->dir.header.root, set, node, table);
860
861 return new;
862 }
863
864 /**
865 * get_subdir - find or create a subdir with the specified name.
866 * @dir: Directory to create the subdirectory in
867 * @name: The name of the subdirectory to find or create
868 * @namelen: The length of name
869 *
870 * Takes a directory with an elevated reference count so we know that
871 * if we drop the lock the directory will not go away. Upon success
872 * the reference is moved from @dir to the returned subdirectory.
873 * Upon error an error code is returned and the reference on @dir is
874 * simply dropped.
875 */
876 static struct ctl_dir *get_subdir(struct ctl_dir *dir,
877 const char *name, int namelen)
878 {
879 struct ctl_table_set *set = dir->header.set;
880 struct ctl_dir *subdir, *new = NULL;
881 int err;
882
883 spin_lock(&sysctl_lock);
884 subdir = find_subdir(dir, name, namelen);
885 if (!IS_ERR(subdir))
886 goto found;
887 if (PTR_ERR(subdir) != -ENOENT)
888 goto failed;
889
890 spin_unlock(&sysctl_lock);
891 new = new_dir(set, name, namelen);
892 spin_lock(&sysctl_lock);
893 subdir = ERR_PTR(-ENOMEM);
894 if (!new)
895 goto failed;
896
897 /* Was the subdir added while we dropped the lock? */
898 subdir = find_subdir(dir, name, namelen);
899 if (!IS_ERR(subdir))
900 goto found;
901 if (PTR_ERR(subdir) != -ENOENT)
902 goto failed;
903
904 /* Nope. Use the our freshly made directory entry. */
905 err = insert_header(dir, &new->header);
906 subdir = ERR_PTR(err);
907 if (err)
908 goto failed;
909 subdir = new;
910 found:
911 subdir->header.nreg++;
912 failed:
913 if (unlikely(IS_ERR(subdir))) {
914 pr_err("sysctl could not get directory: ");
915 sysctl_print_dir(dir);
916 pr_cont("/%*.*s %ld\n",
917 namelen, namelen, name, PTR_ERR(subdir));
918 }
919 drop_sysctl_table(&dir->header);
920 if (new)
921 drop_sysctl_table(&new->header);
922 spin_unlock(&sysctl_lock);
923 return subdir;
924 }
925
926 static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
927 {
928 struct ctl_dir *parent;
929 const char *procname;
930 if (!dir->header.parent)
931 return &set->dir;
932 parent = xlate_dir(set, dir->header.parent);
933 if (IS_ERR(parent))
934 return parent;
935 procname = dir->header.ctl_table[0].procname;
936 return find_subdir(parent, procname, strlen(procname));
937 }
938
939 static int sysctl_follow_link(struct ctl_table_header **phead,
940 struct ctl_table **pentry, struct nsproxy *namespaces)
941 {
942 struct ctl_table_header *head;
943 struct ctl_table_root *root;
944 struct ctl_table_set *set;
945 struct ctl_table *entry;
946 struct ctl_dir *dir;
947 int ret;
948
949 ret = 0;
950 spin_lock(&sysctl_lock);
951 root = (*pentry)->data;
952 set = lookup_header_set(root, namespaces);
953 dir = xlate_dir(set, (*phead)->parent);
954 if (IS_ERR(dir))
955 ret = PTR_ERR(dir);
956 else {
957 const char *procname = (*pentry)->procname;
958 head = NULL;
959 entry = find_entry(&head, dir, procname, strlen(procname));
960 ret = -ENOENT;
961 if (entry && use_table(head)) {
962 unuse_table(*phead);
963 *phead = head;
964 *pentry = entry;
965 ret = 0;
966 }
967 }
968
969 spin_unlock(&sysctl_lock);
970 return ret;
971 }
972
973 static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
974 {
975 struct va_format vaf;
976 va_list args;
977
978 va_start(args, fmt);
979 vaf.fmt = fmt;
980 vaf.va = &args;
981
982 pr_err("sysctl table check failed: %s/%s %pV\n",
983 path, table->procname, &vaf);
984
985 va_end(args);
986 return -EINVAL;
987 }
988
989 static int sysctl_check_table(const char *path, struct ctl_table *table)
990 {
991 int err = 0;
992 for (; table->procname; table++) {
993 if (table->child)
994 err = sysctl_err(path, table, "Not a file");
995
996 if ((table->proc_handler == proc_dostring) ||
997 (table->proc_handler == proc_dointvec) ||
998 (table->proc_handler == proc_dointvec_minmax) ||
999 (table->proc_handler == proc_dointvec_jiffies) ||
1000 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1001 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1002 (table->proc_handler == proc_doulongvec_minmax) ||
1003 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1004 if (!table->data)
1005 err = sysctl_err(path, table, "No data");
1006 if (!table->maxlen)
1007 err = sysctl_err(path, table, "No maxlen");
1008 }
1009 if (!table->proc_handler)
1010 err = sysctl_err(path, table, "No proc_handler");
1011
1012 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1013 err = sysctl_err(path, table, "bogus .mode 0%o",
1014 table->mode);
1015 }
1016 return err;
1017 }
1018
1019 static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1020 struct ctl_table_root *link_root)
1021 {
1022 struct ctl_table *link_table, *entry, *link;
1023 struct ctl_table_header *links;
1024 struct ctl_node *node;
1025 char *link_name;
1026 int nr_entries, name_bytes;
1027
1028 name_bytes = 0;
1029 nr_entries = 0;
1030 for (entry = table; entry->procname; entry++) {
1031 nr_entries++;
1032 name_bytes += strlen(entry->procname) + 1;
1033 }
1034
1035 links = kzalloc(sizeof(struct ctl_table_header) +
1036 sizeof(struct ctl_node)*nr_entries +
1037 sizeof(struct ctl_table)*(nr_entries + 1) +
1038 name_bytes,
1039 GFP_KERNEL);
1040
1041 if (!links)
1042 return NULL;
1043
1044 node = (struct ctl_node *)(links + 1);
1045 link_table = (struct ctl_table *)(node + nr_entries);
1046 link_name = (char *)&link_table[nr_entries + 1];
1047
1048 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1049 int len = strlen(entry->procname) + 1;
1050 memcpy(link_name, entry->procname, len);
1051 link->procname = link_name;
1052 link->mode = S_IFLNK|S_IRWXUGO;
1053 link->data = link_root;
1054 link_name += len;
1055 }
1056 init_header(links, dir->header.root, dir->header.set, node, link_table);
1057 links->nreg = nr_entries;
1058
1059 return links;
1060 }
1061
1062 static bool get_links(struct ctl_dir *dir,
1063 struct ctl_table *table, struct ctl_table_root *link_root)
1064 {
1065 struct ctl_table_header *head;
1066 struct ctl_table *entry, *link;
1067
1068 /* Are there links available for every entry in table? */
1069 for (entry = table; entry->procname; entry++) {
1070 const char *procname = entry->procname;
1071 link = find_entry(&head, dir, procname, strlen(procname));
1072 if (!link)
1073 return false;
1074 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1075 continue;
1076 if (S_ISLNK(link->mode) && (link->data == link_root))
1077 continue;
1078 return false;
1079 }
1080
1081 /* The checks passed. Increase the registration count on the links */
1082 for (entry = table; entry->procname; entry++) {
1083 const char *procname = entry->procname;
1084 link = find_entry(&head, dir, procname, strlen(procname));
1085 head->nreg++;
1086 }
1087 return true;
1088 }
1089
1090 static int insert_links(struct ctl_table_header *head)
1091 {
1092 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1093 struct ctl_dir *core_parent = NULL;
1094 struct ctl_table_header *links;
1095 int err;
1096
1097 if (head->set == root_set)
1098 return 0;
1099
1100 core_parent = xlate_dir(root_set, head->parent);
1101 if (IS_ERR(core_parent))
1102 return 0;
1103
1104 if (get_links(core_parent, head->ctl_table, head->root))
1105 return 0;
1106
1107 core_parent->header.nreg++;
1108 spin_unlock(&sysctl_lock);
1109
1110 links = new_links(core_parent, head->ctl_table, head->root);
1111
1112 spin_lock(&sysctl_lock);
1113 err = -ENOMEM;
1114 if (!links)
1115 goto out;
1116
1117 err = 0;
1118 if (get_links(core_parent, head->ctl_table, head->root)) {
1119 kfree(links);
1120 goto out;
1121 }
1122
1123 err = insert_header(core_parent, links);
1124 if (err)
1125 kfree(links);
1126 out:
1127 drop_sysctl_table(&core_parent->header);
1128 return err;
1129 }
1130
1131 /**
1132 * __register_sysctl_table - register a leaf sysctl table
1133 * @set: Sysctl tree to register on
1134 * @path: The path to the directory the sysctl table is in.
1135 * @table: the top-level table structure
1136 *
1137 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1138 * array. A completely 0 filled entry terminates the table.
1139 *
1140 * The members of the &struct ctl_table structure are used as follows:
1141 *
1142 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1143 * enter a sysctl file
1144 *
1145 * data - a pointer to data for use by proc_handler
1146 *
1147 * maxlen - the maximum size in bytes of the data
1148 *
1149 * mode - the file permissions for the /proc/sys file
1150 *
1151 * child - must be %NULL.
1152 *
1153 * proc_handler - the text handler routine (described below)
1154 *
1155 * extra1, extra2 - extra pointers usable by the proc handler routines
1156 *
1157 * Leaf nodes in the sysctl tree will be represented by a single file
1158 * under /proc; non-leaf nodes will be represented by directories.
1159 *
1160 * There must be a proc_handler routine for any terminal nodes.
1161 * Several default handlers are available to cover common cases -
1162 *
1163 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1164 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1165 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1166 *
1167 * It is the handler's job to read the input buffer from user memory
1168 * and process it. The handler should return 0 on success.
1169 *
1170 * This routine returns %NULL on a failure to register, and a pointer
1171 * to the table header on success.
1172 */
1173 struct ctl_table_header *__register_sysctl_table(
1174 struct ctl_table_set *set,
1175 const char *path, struct ctl_table *table)
1176 {
1177 struct ctl_table_root *root = set->dir.header.root;
1178 struct ctl_table_header *header;
1179 const char *name, *nextname;
1180 struct ctl_dir *dir;
1181 struct ctl_table *entry;
1182 struct ctl_node *node;
1183 int nr_entries = 0;
1184
1185 for (entry = table; entry->procname; entry++)
1186 nr_entries++;
1187
1188 header = kzalloc(sizeof(struct ctl_table_header) +
1189 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1190 if (!header)
1191 return NULL;
1192
1193 node = (struct ctl_node *)(header + 1);
1194 init_header(header, root, set, node, table);
1195 if (sysctl_check_table(path, table))
1196 goto fail;
1197
1198 spin_lock(&sysctl_lock);
1199 dir = &set->dir;
1200 /* Reference moved down the diretory tree get_subdir */
1201 dir->header.nreg++;
1202 spin_unlock(&sysctl_lock);
1203
1204 /* Find the directory for the ctl_table */
1205 for (name = path; name; name = nextname) {
1206 int namelen;
1207 nextname = strchr(name, '/');
1208 if (nextname) {
1209 namelen = nextname - name;
1210 nextname++;
1211 } else {
1212 namelen = strlen(name);
1213 }
1214 if (namelen == 0)
1215 continue;
1216
1217 dir = get_subdir(dir, name, namelen);
1218 if (IS_ERR(dir))
1219 goto fail;
1220 }
1221
1222 spin_lock(&sysctl_lock);
1223 if (insert_header(dir, header))
1224 goto fail_put_dir_locked;
1225
1226 drop_sysctl_table(&dir->header);
1227 spin_unlock(&sysctl_lock);
1228
1229 return header;
1230
1231 fail_put_dir_locked:
1232 drop_sysctl_table(&dir->header);
1233 spin_unlock(&sysctl_lock);
1234 fail:
1235 kfree(header);
1236 dump_stack();
1237 return NULL;
1238 }
1239
1240 /**
1241 * register_sysctl - register a sysctl table
1242 * @path: The path to the directory the sysctl table is in.
1243 * @table: the table structure
1244 *
1245 * Register a sysctl table. @table should be a filled in ctl_table
1246 * array. A completely 0 filled entry terminates the table.
1247 *
1248 * See __register_sysctl_table for more details.
1249 */
1250 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1251 {
1252 return __register_sysctl_table(&sysctl_table_root.default_set,
1253 path, table);
1254 }
1255 EXPORT_SYMBOL(register_sysctl);
1256
1257 static char *append_path(const char *path, char *pos, const char *name)
1258 {
1259 int namelen;
1260 namelen = strlen(name);
1261 if (((pos - path) + namelen + 2) >= PATH_MAX)
1262 return NULL;
1263 memcpy(pos, name, namelen);
1264 pos[namelen] = '/';
1265 pos[namelen + 1] = '\0';
1266 pos += namelen + 1;
1267 return pos;
1268 }
1269
1270 static int count_subheaders(struct ctl_table *table)
1271 {
1272 int has_files = 0;
1273 int nr_subheaders = 0;
1274 struct ctl_table *entry;
1275
1276 /* special case: no directory and empty directory */
1277 if (!table || !table->procname)
1278 return 1;
1279
1280 for (entry = table; entry->procname; entry++) {
1281 if (entry->child)
1282 nr_subheaders += count_subheaders(entry->child);
1283 else
1284 has_files = 1;
1285 }
1286 return nr_subheaders + has_files;
1287 }
1288
1289 static int register_leaf_sysctl_tables(const char *path, char *pos,
1290 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1291 struct ctl_table *table)
1292 {
1293 struct ctl_table *ctl_table_arg = NULL;
1294 struct ctl_table *entry, *files;
1295 int nr_files = 0;
1296 int nr_dirs = 0;
1297 int err = -ENOMEM;
1298
1299 for (entry = table; entry->procname; entry++) {
1300 if (entry->child)
1301 nr_dirs++;
1302 else
1303 nr_files++;
1304 }
1305
1306 files = table;
1307 /* If there are mixed files and directories we need a new table */
1308 if (nr_dirs && nr_files) {
1309 struct ctl_table *new;
1310 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1311 GFP_KERNEL);
1312 if (!files)
1313 goto out;
1314
1315 ctl_table_arg = files;
1316 for (new = files, entry = table; entry->procname; entry++) {
1317 if (entry->child)
1318 continue;
1319 *new = *entry;
1320 new++;
1321 }
1322 }
1323
1324 /* Register everything except a directory full of subdirectories */
1325 if (nr_files || !nr_dirs) {
1326 struct ctl_table_header *header;
1327 header = __register_sysctl_table(set, path, files);
1328 if (!header) {
1329 kfree(ctl_table_arg);
1330 goto out;
1331 }
1332
1333 /* Remember if we need to free the file table */
1334 header->ctl_table_arg = ctl_table_arg;
1335 **subheader = header;
1336 (*subheader)++;
1337 }
1338
1339 /* Recurse into the subdirectories. */
1340 for (entry = table; entry->procname; entry++) {
1341 char *child_pos;
1342
1343 if (!entry->child)
1344 continue;
1345
1346 err = -ENAMETOOLONG;
1347 child_pos = append_path(path, pos, entry->procname);
1348 if (!child_pos)
1349 goto out;
1350
1351 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1352 set, entry->child);
1353 pos[0] = '\0';
1354 if (err)
1355 goto out;
1356 }
1357 err = 0;
1358 out:
1359 /* On failure our caller will unregister all registered subheaders */
1360 return err;
1361 }
1362
1363 /**
1364 * __register_sysctl_paths - register a sysctl table hierarchy
1365 * @set: Sysctl tree to register on
1366 * @path: The path to the directory the sysctl table is in.
1367 * @table: the top-level table structure
1368 *
1369 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1370 * array. A completely 0 filled entry terminates the table.
1371 *
1372 * See __register_sysctl_table for more details.
1373 */
1374 struct ctl_table_header *__register_sysctl_paths(
1375 struct ctl_table_set *set,
1376 const struct ctl_path *path, struct ctl_table *table)
1377 {
1378 struct ctl_table *ctl_table_arg = table;
1379 int nr_subheaders = count_subheaders(table);
1380 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1381 const struct ctl_path *component;
1382 char *new_path, *pos;
1383
1384 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1385 if (!new_path)
1386 return NULL;
1387
1388 pos[0] = '\0';
1389 for (component = path; component->procname; component++) {
1390 pos = append_path(new_path, pos, component->procname);
1391 if (!pos)
1392 goto out;
1393 }
1394 while (table->procname && table->child && !table[1].procname) {
1395 pos = append_path(new_path, pos, table->procname);
1396 if (!pos)
1397 goto out;
1398 table = table->child;
1399 }
1400 if (nr_subheaders == 1) {
1401 header = __register_sysctl_table(set, new_path, table);
1402 if (header)
1403 header->ctl_table_arg = ctl_table_arg;
1404 } else {
1405 header = kzalloc(sizeof(*header) +
1406 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1407 if (!header)
1408 goto out;
1409
1410 subheaders = (struct ctl_table_header **) (header + 1);
1411 subheader = subheaders;
1412 header->ctl_table_arg = ctl_table_arg;
1413
1414 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1415 set, table))
1416 goto err_register_leaves;
1417 }
1418
1419 out:
1420 kfree(new_path);
1421 return header;
1422
1423 err_register_leaves:
1424 while (subheader > subheaders) {
1425 struct ctl_table_header *subh = *(--subheader);
1426 struct ctl_table *table = subh->ctl_table_arg;
1427 unregister_sysctl_table(subh);
1428 kfree(table);
1429 }
1430 kfree(header);
1431 header = NULL;
1432 goto out;
1433 }
1434
1435 /**
1436 * register_sysctl_table_path - register a sysctl table hierarchy
1437 * @path: The path to the directory the sysctl table is in.
1438 * @table: the top-level table structure
1439 *
1440 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1441 * array. A completely 0 filled entry terminates the table.
1442 *
1443 * See __register_sysctl_paths for more details.
1444 */
1445 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1446 struct ctl_table *table)
1447 {
1448 return __register_sysctl_paths(&sysctl_table_root.default_set,
1449 path, table);
1450 }
1451 EXPORT_SYMBOL(register_sysctl_paths);
1452
1453 /**
1454 * register_sysctl_table - register a sysctl table hierarchy
1455 * @table: the top-level table structure
1456 *
1457 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1458 * array. A completely 0 filled entry terminates the table.
1459 *
1460 * See register_sysctl_paths for more details.
1461 */
1462 struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1463 {
1464 static const struct ctl_path null_path[] = { {} };
1465
1466 return register_sysctl_paths(null_path, table);
1467 }
1468 EXPORT_SYMBOL(register_sysctl_table);
1469
1470 static void put_links(struct ctl_table_header *header)
1471 {
1472 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1473 struct ctl_table_root *root = header->root;
1474 struct ctl_dir *parent = header->parent;
1475 struct ctl_dir *core_parent;
1476 struct ctl_table *entry;
1477
1478 if (header->set == root_set)
1479 return;
1480
1481 core_parent = xlate_dir(root_set, parent);
1482 if (IS_ERR(core_parent))
1483 return;
1484
1485 for (entry = header->ctl_table; entry->procname; entry++) {
1486 struct ctl_table_header *link_head;
1487 struct ctl_table *link;
1488 const char *name = entry->procname;
1489
1490 link = find_entry(&link_head, core_parent, name, strlen(name));
1491 if (link &&
1492 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1493 (S_ISLNK(link->mode) && (link->data == root)))) {
1494 drop_sysctl_table(link_head);
1495 }
1496 else {
1497 pr_err("sysctl link missing during unregister: ");
1498 sysctl_print_dir(parent);
1499 pr_cont("/%s\n", name);
1500 }
1501 }
1502 }
1503
1504 static void drop_sysctl_table(struct ctl_table_header *header)
1505 {
1506 struct ctl_dir *parent = header->parent;
1507
1508 if (--header->nreg)
1509 return;
1510
1511 put_links(header);
1512 start_unregistering(header);
1513 if (!--header->count)
1514 kfree_rcu(header, rcu);
1515
1516 if (parent)
1517 drop_sysctl_table(&parent->header);
1518 }
1519
1520 /**
1521 * unregister_sysctl_table - unregister a sysctl table hierarchy
1522 * @header: the header returned from register_sysctl_table
1523 *
1524 * Unregisters the sysctl table and all children. proc entries may not
1525 * actually be removed until they are no longer used by anyone.
1526 */
1527 void unregister_sysctl_table(struct ctl_table_header * header)
1528 {
1529 int nr_subheaders;
1530 might_sleep();
1531
1532 if (header == NULL)
1533 return;
1534
1535 nr_subheaders = count_subheaders(header->ctl_table_arg);
1536 if (unlikely(nr_subheaders > 1)) {
1537 struct ctl_table_header **subheaders;
1538 int i;
1539
1540 subheaders = (struct ctl_table_header **)(header + 1);
1541 for (i = nr_subheaders -1; i >= 0; i--) {
1542 struct ctl_table_header *subh = subheaders[i];
1543 struct ctl_table *table = subh->ctl_table_arg;
1544 unregister_sysctl_table(subh);
1545 kfree(table);
1546 }
1547 kfree(header);
1548 return;
1549 }
1550
1551 spin_lock(&sysctl_lock);
1552 drop_sysctl_table(header);
1553 spin_unlock(&sysctl_lock);
1554 }
1555 EXPORT_SYMBOL(unregister_sysctl_table);
1556
1557 void setup_sysctl_set(struct ctl_table_set *set,
1558 struct ctl_table_root *root,
1559 int (*is_seen)(struct ctl_table_set *))
1560 {
1561 memset(set, 0, sizeof(*set));
1562 set->is_seen = is_seen;
1563 init_header(&set->dir.header, root, set, NULL, root_table);
1564 }
1565
1566 void retire_sysctl_set(struct ctl_table_set *set)
1567 {
1568 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1569 }
1570
1571 int __init proc_sys_init(void)
1572 {
1573 struct proc_dir_entry *proc_sys_root;
1574
1575 proc_sys_root = proc_mkdir("sys", NULL);
1576 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1577 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1578 proc_sys_root->nlink = 0;
1579
1580 return sysctl_init();
1581 }
Linux kernel - Deliverables
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