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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
16static const struct dentry_operations proc_sys_dentry_operations;
17static const struct file_operations proc_sys_file_operations;
18static const struct inode_operations proc_sys_inode_operations;
19static const struct file_operations proc_sys_dir_file_operations;
20static const struct inode_operations proc_sys_dir_operations;
21
22/* Support for permanently empty directories */
23
24struct ctl_table sysctl_mount_point[] = {
25 { }
26};
27
28static bool is_empty_dir(struct ctl_table_header *head)
29{
30 return head->ctl_table[0].child == sysctl_mount_point;
31}
32
33static void set_empty_dir(struct ctl_dir *dir)
34{
35 dir->header.ctl_table[0].child = sysctl_mount_point;
36}
37
38static void clear_empty_dir(struct ctl_dir *dir)
39
40{
41 dir->header.ctl_table[0].child = NULL;
42}
43
44void proc_sys_poll_notify(struct ctl_table_poll *poll)
45{
46 if (!poll)
47 return;
48
49 atomic_inc(&poll->event);
50 wake_up_interruptible(&poll->wait);
51}
52
53static struct ctl_table root_table[] = {
54 {
55 .procname = "",
56 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
57 },
58 { }
59};
60static struct ctl_table_root sysctl_table_root = {
61 .default_set.dir.header = {
62 {{.count = 1,
63 .nreg = 1,
64 .ctl_table = root_table }},
65 .ctl_table_arg = root_table,
66 .root = &sysctl_table_root,
67 .set = &sysctl_table_root.default_set,
68 },
69};
70
71static DEFINE_SPINLOCK(sysctl_lock);
72
73static void drop_sysctl_table(struct ctl_table_header *header);
74static int sysctl_follow_link(struct ctl_table_header **phead,
75 struct ctl_table **pentry, struct nsproxy *namespaces);
76static int insert_links(struct ctl_table_header *head);
77static void put_links(struct ctl_table_header *header);
78
79static void sysctl_print_dir(struct ctl_dir *dir)
80{
81 if (dir->header.parent)
82 sysctl_print_dir(dir->header.parent);
83 pr_cont("%s/", dir->header.ctl_table[0].procname);
84}
85
86static int namecmp(const char *name1, int len1, const char *name2, int len2)
87{
88 int minlen;
89 int cmp;
90
91 minlen = len1;
92 if (minlen > len2)
93 minlen = len2;
94
95 cmp = memcmp(name1, name2, minlen);
96 if (cmp == 0)
97 cmp = len1 - len2;
98 return cmp;
99}
100
101/* Called under sysctl_lock */
102static struct ctl_table *find_entry(struct ctl_table_header **phead,
103 struct ctl_dir *dir, const char *name, int namelen)
104{
105 struct ctl_table_header *head;
106 struct ctl_table *entry;
107 struct rb_node *node = dir->root.rb_node;
108
109 while (node)
110 {
111 struct ctl_node *ctl_node;
112 const char *procname;
113 int cmp;
114
115 ctl_node = rb_entry(node, struct ctl_node, node);
116 head = ctl_node->header;
117 entry = &head->ctl_table[ctl_node - head->node];
118 procname = entry->procname;
119
120 cmp = namecmp(name, namelen, procname, strlen(procname));
121 if (cmp < 0)
122 node = node->rb_left;
123 else if (cmp > 0)
124 node = node->rb_right;
125 else {
126 *phead = head;
127 return entry;
128 }
129 }
130 return NULL;
131}
132
133static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
134{
135 struct rb_node *node = &head->node[entry - head->ctl_table].node;
136 struct rb_node **p = &head->parent->root.rb_node;
137 struct rb_node *parent = NULL;
138 const char *name = entry->procname;
139 int namelen = strlen(name);
140
141 while (*p) {
142 struct ctl_table_header *parent_head;
143 struct ctl_table *parent_entry;
144 struct ctl_node *parent_node;
145 const char *parent_name;
146 int cmp;
147
148 parent = *p;
149 parent_node = rb_entry(parent, struct ctl_node, node);
150 parent_head = parent_node->header;
151 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
152 parent_name = parent_entry->procname;
153
154 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
155 if (cmp < 0)
156 p = &(*p)->rb_left;
157 else if (cmp > 0)
158 p = &(*p)->rb_right;
159 else {
160 pr_err("sysctl duplicate entry: ");
161 sysctl_print_dir(head->parent);
162 pr_cont("/%s\n", entry->procname);
163 return -EEXIST;
164 }
165 }
166
167 rb_link_node(node, parent, p);
168 rb_insert_color(node, &head->parent->root);
169 return 0;
170}
171
172static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
173{
174 struct rb_node *node = &head->node[entry - head->ctl_table].node;
175
176 rb_erase(node, &head->parent->root);
177}
178
179static void init_header(struct ctl_table_header *head,
180 struct ctl_table_root *root, struct ctl_table_set *set,
181 struct ctl_node *node, struct ctl_table *table)
182{
183 head->ctl_table = table;
184 head->ctl_table_arg = table;
185 head->used = 0;
186 head->count = 1;
187 head->nreg = 1;
188 head->unregistering = NULL;
189 head->root = root;
190 head->set = set;
191 head->parent = NULL;
192 head->node = node;
193 if (node) {
194 struct ctl_table *entry;
195 for (entry = table; entry->procname; entry++, node++)
196 node->header = head;
197 }
198}
199
200static void erase_header(struct ctl_table_header *head)
201{
202 struct ctl_table *entry;
203 for (entry = head->ctl_table; entry->procname; entry++)
204 erase_entry(head, entry);
205}
206
207static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
208{
209 struct ctl_table *entry;
210 int err;
211
212 /* Is this a permanently empty directory? */
213 if (is_empty_dir(&dir->header))
214 return -EROFS;
215
216 /* Am I creating a permanently empty directory? */
217 if (header->ctl_table == sysctl_mount_point) {
218 if (!RB_EMPTY_ROOT(&dir->root))
219 return -EINVAL;
220 set_empty_dir(dir);
221 }
222
223 dir->header.nreg++;
224 header->parent = dir;
225 err = insert_links(header);
226 if (err)
227 goto fail_links;
228 for (entry = header->ctl_table; entry->procname; entry++) {
229 err = insert_entry(header, entry);
230 if (err)
231 goto fail;
232 }
233 return 0;
234fail:
235 erase_header(header);
236 put_links(header);
237fail_links:
238 if (header->ctl_table == sysctl_mount_point)
239 clear_empty_dir(dir);
240 header->parent = NULL;
241 drop_sysctl_table(&dir->header);
242 return err;
243}
244
245/* called under sysctl_lock */
246static int use_table(struct ctl_table_header *p)
247{
248 if (unlikely(p->unregistering))
249 return 0;
250 p->used++;
251 return 1;
252}
253
254/* called under sysctl_lock */
255static void unuse_table(struct ctl_table_header *p)
256{
257 if (!--p->used)
258 if (unlikely(p->unregistering))
259 complete(p->unregistering);
260}
261
262/* called under sysctl_lock, will reacquire if has to wait */
263static void start_unregistering(struct ctl_table_header *p)
264{
265 /*
266 * if p->used is 0, nobody will ever touch that entry again;
267 * we'll eliminate all paths to it before dropping sysctl_lock
268 */
269 if (unlikely(p->used)) {
270 struct completion wait;
271 init_completion(&wait);
272 p->unregistering = &wait;
273 spin_unlock(&sysctl_lock);
274 wait_for_completion(&wait);
275 spin_lock(&sysctl_lock);
276 } else {
277 /* anything non-NULL; we'll never dereference it */
278 p->unregistering = ERR_PTR(-EINVAL);
279 }
280 /*
281 * do not remove from the list until nobody holds it; walking the
282 * list in do_sysctl() relies on that.
283 */
284 erase_header(p);
285}
286
287static void sysctl_head_get(struct ctl_table_header *head)
288{
289 spin_lock(&sysctl_lock);
290 head->count++;
291 spin_unlock(&sysctl_lock);
292}
293
294void sysctl_head_put(struct ctl_table_header *head)
295{
296 spin_lock(&sysctl_lock);
297 if (!--head->count)
298 kfree_rcu(head, rcu);
299 spin_unlock(&sysctl_lock);
300}
301
302static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
303{
304 BUG_ON(!head);
305 spin_lock(&sysctl_lock);
306 if (!use_table(head))
307 head = ERR_PTR(-ENOENT);
308 spin_unlock(&sysctl_lock);
309 return head;
310}
311
312static void sysctl_head_finish(struct ctl_table_header *head)
313{
314 if (!head)
315 return;
316 spin_lock(&sysctl_lock);
317 unuse_table(head);
318 spin_unlock(&sysctl_lock);
319}
320
321static struct ctl_table_set *
322lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces)
323{
324 struct ctl_table_set *set = &root->default_set;
325 if (root->lookup)
326 set = root->lookup(root, namespaces);
327 return set;
328}
329
330static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
331 struct ctl_dir *dir,
332 const char *name, int namelen)
333{
334 struct ctl_table_header *head;
335 struct ctl_table *entry;
336
337 spin_lock(&sysctl_lock);
338 entry = find_entry(&head, dir, name, namelen);
339 if (entry && use_table(head))
340 *phead = head;
341 else
342 entry = NULL;
343 spin_unlock(&sysctl_lock);
344 return entry;
345}
346
347static struct ctl_node *first_usable_entry(struct rb_node *node)
348{
349 struct ctl_node *ctl_node;
350
351 for (;node; node = rb_next(node)) {
352 ctl_node = rb_entry(node, struct ctl_node, node);
353 if (use_table(ctl_node->header))
354 return ctl_node;
355 }
356 return NULL;
357}
358
359static void first_entry(struct ctl_dir *dir,
360 struct ctl_table_header **phead, struct ctl_table **pentry)
361{
362 struct ctl_table_header *head = NULL;
363 struct ctl_table *entry = NULL;
364 struct ctl_node *ctl_node;
365
366 spin_lock(&sysctl_lock);
367 ctl_node = first_usable_entry(rb_first(&dir->root));
368 spin_unlock(&sysctl_lock);
369 if (ctl_node) {
370 head = ctl_node->header;
371 entry = &head->ctl_table[ctl_node - head->node];
372 }
373 *phead = head;
374 *pentry = entry;
375}
376
377static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
378{
379 struct ctl_table_header *head = *phead;
380 struct ctl_table *entry = *pentry;
381 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
382
383 spin_lock(&sysctl_lock);
384 unuse_table(head);
385
386 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
387 spin_unlock(&sysctl_lock);
388 head = NULL;
389 if (ctl_node) {
390 head = ctl_node->header;
391 entry = &head->ctl_table[ctl_node - head->node];
392 }
393 *phead = head;
394 *pentry = entry;
395}
396
397void register_sysctl_root(struct ctl_table_root *root)
398{
399}
400
401/*
402 * sysctl_perm does NOT grant the superuser all rights automatically, because
403 * some sysctl variables are readonly even to root.
404 */
405
406static int test_perm(int mode, int op)
407{
408 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
409 mode >>= 6;
410 else if (in_egroup_p(GLOBAL_ROOT_GID))
411 mode >>= 3;
412 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
413 return 0;
414 return -EACCES;
415}
416
417static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
418{
419 struct ctl_table_root *root = head->root;
420 int mode;
421
422 if (root->permissions)
423 mode = root->permissions(head, table);
424 else
425 mode = table->mode;
426
427 return test_perm(mode, op);
428}
429
430static struct inode *proc_sys_make_inode(struct super_block *sb,
431 struct ctl_table_header *head, struct ctl_table *table)
432{
433 struct inode *inode;
434 struct proc_inode *ei;
435
436 inode = new_inode(sb);
437 if (!inode)
438 goto out;
439
440 inode->i_ino = get_next_ino();
441
442 sysctl_head_get(head);
443 ei = PROC_I(inode);
444 ei->sysctl = head;
445 ei->sysctl_entry = table;
446
447 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
448 inode->i_mode = table->mode;
449 if (!S_ISDIR(table->mode)) {
450 inode->i_mode |= S_IFREG;
451 inode->i_op = &proc_sys_inode_operations;
452 inode->i_fop = &proc_sys_file_operations;
453 } else {
454 inode->i_mode |= S_IFDIR;
455 inode->i_op = &proc_sys_dir_operations;
456 inode->i_fop = &proc_sys_dir_file_operations;
457 if (is_empty_dir(head))
458 make_empty_dir_inode(inode);
459 }
460out:
461 return inode;
462}
463
464static struct ctl_table_header *grab_header(struct inode *inode)
465{
466 struct ctl_table_header *head = PROC_I(inode)->sysctl;
467 if (!head)
468 head = &sysctl_table_root.default_set.dir.header;
469 return sysctl_head_grab(head);
470}
471
472static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
473 unsigned int flags)
474{
475 struct ctl_table_header *head = grab_header(dir);
476 struct ctl_table_header *h = NULL;
477 struct qstr *name = &dentry->d_name;
478 struct ctl_table *p;
479 struct inode *inode;
480 struct dentry *err = ERR_PTR(-ENOENT);
481 struct ctl_dir *ctl_dir;
482 int ret;
483
484 if (IS_ERR(head))
485 return ERR_CAST(head);
486
487 ctl_dir = container_of(head, struct ctl_dir, header);
488
489 p = lookup_entry(&h, ctl_dir, name->name, name->len);
490 if (!p)
491 goto out;
492
493 if (S_ISLNK(p->mode)) {
494 ret = sysctl_follow_link(&h, &p, current->nsproxy);
495 err = ERR_PTR(ret);
496 if (ret)
497 goto out;
498 }
499
500 err = ERR_PTR(-ENOMEM);
501 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
502 if (!inode)
503 goto out;
504
505 err = NULL;
506 d_set_d_op(dentry, &proc_sys_dentry_operations);
507 d_add(dentry, inode);
508
509out:
510 if (h)
511 sysctl_head_finish(h);
512 sysctl_head_finish(head);
513 return err;
514}
515
516static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
517 size_t count, loff_t *ppos, int write)
518{
519 struct inode *inode = file_inode(filp);
520 struct ctl_table_header *head = grab_header(inode);
521 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
522 ssize_t error;
523 size_t res;
524
525 if (IS_ERR(head))
526 return PTR_ERR(head);
527
528 /*
529 * At this point we know that the sysctl was not unregistered
530 * and won't be until we finish.
531 */
532 error = -EPERM;
533 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
534 goto out;
535
536 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
537 error = -EINVAL;
538 if (!table->proc_handler)
539 goto out;
540
541 /* careful: calling conventions are nasty here */
542 res = count;
543 error = table->proc_handler(table, write, buf, &res, ppos);
544 if (!error)
545 error = res;
546out:
547 sysctl_head_finish(head);
548
549 return error;
550}
551
552static ssize_t proc_sys_read(struct file *filp, char __user *buf,
553 size_t count, loff_t *ppos)
554{
555 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
556}
557
558static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
559 size_t count, loff_t *ppos)
560{
561 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
562}
563
564static int proc_sys_open(struct inode *inode, struct file *filp)
565{
566 struct ctl_table_header *head = grab_header(inode);
567 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
568
569 /* sysctl was unregistered */
570 if (IS_ERR(head))
571 return PTR_ERR(head);
572
573 if (table->poll)
574 filp->private_data = proc_sys_poll_event(table->poll);
575
576 sysctl_head_finish(head);
577
578 return 0;
579}
580
581static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
582{
583 struct inode *inode = file_inode(filp);
584 struct ctl_table_header *head = grab_header(inode);
585 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
586 unsigned int ret = DEFAULT_POLLMASK;
587 unsigned long event;
588
589 /* sysctl was unregistered */
590 if (IS_ERR(head))
591 return POLLERR | POLLHUP;
592
593 if (!table->proc_handler)
594 goto out;
595
596 if (!table->poll)
597 goto out;
598
599 event = (unsigned long)filp->private_data;
600 poll_wait(filp, &table->poll->wait, wait);
601
602 if (event != atomic_read(&table->poll->event)) {
603 filp->private_data = proc_sys_poll_event(table->poll);
604 ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI;
605 }
606
607out:
608 sysctl_head_finish(head);
609
610 return ret;
611}
612
613static bool proc_sys_fill_cache(struct file *file,
614 struct dir_context *ctx,
615 struct ctl_table_header *head,
616 struct ctl_table *table)
617{
618 struct dentry *child, *dir = file->f_path.dentry;
619 struct inode *inode;
620 struct qstr qname;
621 ino_t ino = 0;
622 unsigned type = DT_UNKNOWN;
623
624 qname.name = table->procname;
625 qname.len = strlen(table->procname);
626 qname.hash = full_name_hash(qname.name, qname.len);
627
628 child = d_lookup(dir, &qname);
629 if (!child) {
630 child = d_alloc(dir, &qname);
631 if (child) {
632 inode = proc_sys_make_inode(dir->d_sb, head, table);
633 if (!inode) {
634 dput(child);
635 return false;
636 } else {
637 d_set_d_op(child, &proc_sys_dentry_operations);
638 d_add(child, inode);
639 }
640 } else {
641 return false;
642 }
643 }
644 inode = d_inode(child);
645 ino = inode->i_ino;
646 type = inode->i_mode >> 12;
647 dput(child);
648 return dir_emit(ctx, qname.name, qname.len, ino, type);
649}
650
651static bool proc_sys_link_fill_cache(struct file *file,
652 struct dir_context *ctx,
653 struct ctl_table_header *head,
654 struct ctl_table *table)
655{
656 bool ret = true;
657 head = sysctl_head_grab(head);
658
659 if (S_ISLNK(table->mode)) {
660 /* It is not an error if we can not follow the link ignore it */
661 int err = sysctl_follow_link(&head, &table, current->nsproxy);
662 if (err)
663 goto out;
664 }
665
666 ret = proc_sys_fill_cache(file, ctx, head, table);
667out:
668 sysctl_head_finish(head);
669 return ret;
670}
671
672static int scan(struct ctl_table_header *head, struct ctl_table *table,
673 unsigned long *pos, struct file *file,
674 struct dir_context *ctx)
675{
676 bool res;
677
678 if ((*pos)++ < ctx->pos)
679 return true;
680
681 if (unlikely(S_ISLNK(table->mode)))
682 res = proc_sys_link_fill_cache(file, ctx, head, table);
683 else
684 res = proc_sys_fill_cache(file, ctx, head, table);
685
686 if (res)
687 ctx->pos = *pos;
688
689 return res;
690}
691
692static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
693{
694 struct ctl_table_header *head = grab_header(file_inode(file));
695 struct ctl_table_header *h = NULL;
696 struct ctl_table *entry;
697 struct ctl_dir *ctl_dir;
698 unsigned long pos;
699
700 if (IS_ERR(head))
701 return PTR_ERR(head);
702
703 ctl_dir = container_of(head, struct ctl_dir, header);
704
705 if (!dir_emit_dots(file, ctx))
706 return 0;
707
708 pos = 2;
709
710 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
711 if (!scan(h, entry, &pos, file, ctx)) {
712 sysctl_head_finish(h);
713 break;
714 }
715 }
716 sysctl_head_finish(head);
717 return 0;
718}
719
720static int proc_sys_permission(struct inode *inode, int mask)
721{
722 /*
723 * sysctl entries that are not writeable,
724 * are _NOT_ writeable, capabilities or not.
725 */
726 struct ctl_table_header *head;
727 struct ctl_table *table;
728 int error;
729
730 /* Executable files are not allowed under /proc/sys/ */
731 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
732 return -EACCES;
733
734 head = grab_header(inode);
735 if (IS_ERR(head))
736 return PTR_ERR(head);
737
738 table = PROC_I(inode)->sysctl_entry;
739 if (!table) /* global root - r-xr-xr-x */
740 error = mask & MAY_WRITE ? -EACCES : 0;
741 else /* Use the permissions on the sysctl table entry */
742 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
743
744 sysctl_head_finish(head);
745 return error;
746}
747
748static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
749{
750 struct inode *inode = d_inode(dentry);
751 int error;
752
753 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
754 return -EPERM;
755
756 error = inode_change_ok(inode, attr);
757 if (error)
758 return error;
759
760 setattr_copy(inode, attr);
761 mark_inode_dirty(inode);
762 return 0;
763}
764
765static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
766{
767 struct inode *inode = d_inode(dentry);
768 struct ctl_table_header *head = grab_header(inode);
769 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
770
771 if (IS_ERR(head))
772 return PTR_ERR(head);
773
774 generic_fillattr(inode, stat);
775 if (table)
776 stat->mode = (stat->mode & S_IFMT) | table->mode;
777
778 sysctl_head_finish(head);
779 return 0;
780}
781
782static const struct file_operations proc_sys_file_operations = {
783 .open = proc_sys_open,
784 .poll = proc_sys_poll,
785 .read = proc_sys_read,
786 .write = proc_sys_write,
787 .llseek = default_llseek,
788};
789
790static const struct file_operations proc_sys_dir_file_operations = {
791 .read = generic_read_dir,
792 .iterate = proc_sys_readdir,
793 .llseek = generic_file_llseek,
794};
795
796static const struct inode_operations proc_sys_inode_operations = {
797 .permission = proc_sys_permission,
798 .setattr = proc_sys_setattr,
799 .getattr = proc_sys_getattr,
800};
801
802static const struct inode_operations proc_sys_dir_operations = {
803 .lookup = proc_sys_lookup,
804 .permission = proc_sys_permission,
805 .setattr = proc_sys_setattr,
806 .getattr = proc_sys_getattr,
807};
808
809static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
810{
811 if (flags & LOOKUP_RCU)
812 return -ECHILD;
813 return !PROC_I(d_inode(dentry))->sysctl->unregistering;
814}
815
816static int proc_sys_delete(const struct dentry *dentry)
817{
818 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
819}
820
821static int sysctl_is_seen(struct ctl_table_header *p)
822{
823 struct ctl_table_set *set = p->set;
824 int res;
825 spin_lock(&sysctl_lock);
826 if (p->unregistering)
827 res = 0;
828 else if (!set->is_seen)
829 res = 1;
830 else
831 res = set->is_seen(set);
832 spin_unlock(&sysctl_lock);
833 return res;
834}
835
836static int proc_sys_compare(const struct dentry *parent, const struct dentry *dentry,
837 unsigned int len, const char *str, const struct qstr *name)
838{
839 struct ctl_table_header *head;
840 struct inode *inode;
841
842 /* Although proc doesn't have negative dentries, rcu-walk means
843 * that inode here can be NULL */
844 /* AV: can it, indeed? */
845 inode = d_inode_rcu(dentry);
846 if (!inode)
847 return 1;
848 if (name->len != len)
849 return 1;
850 if (memcmp(name->name, str, len))
851 return 1;
852 head = rcu_dereference(PROC_I(inode)->sysctl);
853 return !head || !sysctl_is_seen(head);
854}
855
856static const struct dentry_operations proc_sys_dentry_operations = {
857 .d_revalidate = proc_sys_revalidate,
858 .d_delete = proc_sys_delete,
859 .d_compare = proc_sys_compare,
860};
861
862static struct ctl_dir *find_subdir(struct ctl_dir *dir,
863 const char *name, int namelen)
864{
865 struct ctl_table_header *head;
866 struct ctl_table *entry;
867
868 entry = find_entry(&head, dir, name, namelen);
869 if (!entry)
870 return ERR_PTR(-ENOENT);
871 if (!S_ISDIR(entry->mode))
872 return ERR_PTR(-ENOTDIR);
873 return container_of(head, struct ctl_dir, header);
874}
875
876static struct ctl_dir *new_dir(struct ctl_table_set *set,
877 const char *name, int namelen)
878{
879 struct ctl_table *table;
880 struct ctl_dir *new;
881 struct ctl_node *node;
882 char *new_name;
883
884 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
885 sizeof(struct ctl_table)*2 + namelen + 1,
886 GFP_KERNEL);
887 if (!new)
888 return NULL;
889
890 node = (struct ctl_node *)(new + 1);
891 table = (struct ctl_table *)(node + 1);
892 new_name = (char *)(table + 2);
893 memcpy(new_name, name, namelen);
894 new_name[namelen] = '\0';
895 table[0].procname = new_name;
896 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
897 init_header(&new->header, set->dir.header.root, set, node, table);
898
899 return new;
900}
901
902/**
903 * get_subdir - find or create a subdir with the specified name.
904 * @dir: Directory to create the subdirectory in
905 * @name: The name of the subdirectory to find or create
906 * @namelen: The length of name
907 *
908 * Takes a directory with an elevated reference count so we know that
909 * if we drop the lock the directory will not go away. Upon success
910 * the reference is moved from @dir to the returned subdirectory.
911 * Upon error an error code is returned and the reference on @dir is
912 * simply dropped.
913 */
914static struct ctl_dir *get_subdir(struct ctl_dir *dir,
915 const char *name, int namelen)
916{
917 struct ctl_table_set *set = dir->header.set;
918 struct ctl_dir *subdir, *new = NULL;
919 int err;
920
921 spin_lock(&sysctl_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 spin_unlock(&sysctl_lock);
929 new = new_dir(set, name, namelen);
930 spin_lock(&sysctl_lock);
931 subdir = ERR_PTR(-ENOMEM);
932 if (!new)
933 goto failed;
934
935 /* Was the subdir added while we dropped the lock? */
936 subdir = find_subdir(dir, name, namelen);
937 if (!IS_ERR(subdir))
938 goto found;
939 if (PTR_ERR(subdir) != -ENOENT)
940 goto failed;
941
942 /* Nope. Use the our freshly made directory entry. */
943 err = insert_header(dir, &new->header);
944 subdir = ERR_PTR(err);
945 if (err)
946 goto failed;
947 subdir = new;
948found:
949 subdir->header.nreg++;
950failed:
951 if (IS_ERR(subdir)) {
952 pr_err("sysctl could not get directory: ");
953 sysctl_print_dir(dir);
954 pr_cont("/%*.*s %ld\n",
955 namelen, namelen, name, PTR_ERR(subdir));
956 }
957 drop_sysctl_table(&dir->header);
958 if (new)
959 drop_sysctl_table(&new->header);
960 spin_unlock(&sysctl_lock);
961 return subdir;
962}
963
964static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
965{
966 struct ctl_dir *parent;
967 const char *procname;
968 if (!dir->header.parent)
969 return &set->dir;
970 parent = xlate_dir(set, dir->header.parent);
971 if (IS_ERR(parent))
972 return parent;
973 procname = dir->header.ctl_table[0].procname;
974 return find_subdir(parent, procname, strlen(procname));
975}
976
977static int sysctl_follow_link(struct ctl_table_header **phead,
978 struct ctl_table **pentry, struct nsproxy *namespaces)
979{
980 struct ctl_table_header *head;
981 struct ctl_table_root *root;
982 struct ctl_table_set *set;
983 struct ctl_table *entry;
984 struct ctl_dir *dir;
985 int ret;
986
987 ret = 0;
988 spin_lock(&sysctl_lock);
989 root = (*pentry)->data;
990 set = lookup_header_set(root, namespaces);
991 dir = xlate_dir(set, (*phead)->parent);
992 if (IS_ERR(dir))
993 ret = PTR_ERR(dir);
994 else {
995 const char *procname = (*pentry)->procname;
996 head = NULL;
997 entry = find_entry(&head, dir, procname, strlen(procname));
998 ret = -ENOENT;
999 if (entry && use_table(head)) {
1000 unuse_table(*phead);
1001 *phead = head;
1002 *pentry = entry;
1003 ret = 0;
1004 }
1005 }
1006
1007 spin_unlock(&sysctl_lock);
1008 return ret;
1009}
1010
1011static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
1012{
1013 struct va_format vaf;
1014 va_list args;
1015
1016 va_start(args, fmt);
1017 vaf.fmt = fmt;
1018 vaf.va = &args;
1019
1020 pr_err("sysctl table check failed: %s/%s %pV\n",
1021 path, table->procname, &vaf);
1022
1023 va_end(args);
1024 return -EINVAL;
1025}
1026
1027static int sysctl_check_table(const char *path, struct ctl_table *table)
1028{
1029 int err = 0;
1030 for (; table->procname; table++) {
1031 if (table->child)
1032 err = sysctl_err(path, table, "Not a file");
1033
1034 if ((table->proc_handler == proc_dostring) ||
1035 (table->proc_handler == proc_dointvec) ||
1036 (table->proc_handler == proc_dointvec_minmax) ||
1037 (table->proc_handler == proc_dointvec_jiffies) ||
1038 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1039 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1040 (table->proc_handler == proc_doulongvec_minmax) ||
1041 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1042 if (!table->data)
1043 err = sysctl_err(path, table, "No data");
1044 if (!table->maxlen)
1045 err = sysctl_err(path, table, "No maxlen");
1046 }
1047 if (!table->proc_handler)
1048 err = sysctl_err(path, table, "No proc_handler");
1049
1050 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1051 err = sysctl_err(path, table, "bogus .mode 0%o",
1052 table->mode);
1053 }
1054 return err;
1055}
1056
1057static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1058 struct ctl_table_root *link_root)
1059{
1060 struct ctl_table *link_table, *entry, *link;
1061 struct ctl_table_header *links;
1062 struct ctl_node *node;
1063 char *link_name;
1064 int nr_entries, name_bytes;
1065
1066 name_bytes = 0;
1067 nr_entries = 0;
1068 for (entry = table; entry->procname; entry++) {
1069 nr_entries++;
1070 name_bytes += strlen(entry->procname) + 1;
1071 }
1072
1073 links = kzalloc(sizeof(struct ctl_table_header) +
1074 sizeof(struct ctl_node)*nr_entries +
1075 sizeof(struct ctl_table)*(nr_entries + 1) +
1076 name_bytes,
1077 GFP_KERNEL);
1078
1079 if (!links)
1080 return NULL;
1081
1082 node = (struct ctl_node *)(links + 1);
1083 link_table = (struct ctl_table *)(node + nr_entries);
1084 link_name = (char *)&link_table[nr_entries + 1];
1085
1086 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1087 int len = strlen(entry->procname) + 1;
1088 memcpy(link_name, entry->procname, len);
1089 link->procname = link_name;
1090 link->mode = S_IFLNK|S_IRWXUGO;
1091 link->data = link_root;
1092 link_name += len;
1093 }
1094 init_header(links, dir->header.root, dir->header.set, node, link_table);
1095 links->nreg = nr_entries;
1096
1097 return links;
1098}
1099
1100static bool get_links(struct ctl_dir *dir,
1101 struct ctl_table *table, struct ctl_table_root *link_root)
1102{
1103 struct ctl_table_header *head;
1104 struct ctl_table *entry, *link;
1105
1106 /* Are there links available for every entry in table? */
1107 for (entry = table; entry->procname; entry++) {
1108 const char *procname = entry->procname;
1109 link = find_entry(&head, dir, procname, strlen(procname));
1110 if (!link)
1111 return false;
1112 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1113 continue;
1114 if (S_ISLNK(link->mode) && (link->data == link_root))
1115 continue;
1116 return false;
1117 }
1118
1119 /* The checks passed. Increase the registration count on the links */
1120 for (entry = table; entry->procname; entry++) {
1121 const char *procname = entry->procname;
1122 link = find_entry(&head, dir, procname, strlen(procname));
1123 head->nreg++;
1124 }
1125 return true;
1126}
1127
1128static int insert_links(struct ctl_table_header *head)
1129{
1130 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1131 struct ctl_dir *core_parent = NULL;
1132 struct ctl_table_header *links;
1133 int err;
1134
1135 if (head->set == root_set)
1136 return 0;
1137
1138 core_parent = xlate_dir(root_set, head->parent);
1139 if (IS_ERR(core_parent))
1140 return 0;
1141
1142 if (get_links(core_parent, head->ctl_table, head->root))
1143 return 0;
1144
1145 core_parent->header.nreg++;
1146 spin_unlock(&sysctl_lock);
1147
1148 links = new_links(core_parent, head->ctl_table, head->root);
1149
1150 spin_lock(&sysctl_lock);
1151 err = -ENOMEM;
1152 if (!links)
1153 goto out;
1154
1155 err = 0;
1156 if (get_links(core_parent, head->ctl_table, head->root)) {
1157 kfree(links);
1158 goto out;
1159 }
1160
1161 err = insert_header(core_parent, links);
1162 if (err)
1163 kfree(links);
1164out:
1165 drop_sysctl_table(&core_parent->header);
1166 return err;
1167}
1168
1169/**
1170 * __register_sysctl_table - register a leaf sysctl table
1171 * @set: Sysctl tree to register on
1172 * @path: The path to the directory the sysctl table is in.
1173 * @table: the top-level table structure
1174 *
1175 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1176 * array. A completely 0 filled entry terminates the table.
1177 *
1178 * The members of the &struct ctl_table structure are used as follows:
1179 *
1180 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1181 * enter a sysctl file
1182 *
1183 * data - a pointer to data for use by proc_handler
1184 *
1185 * maxlen - the maximum size in bytes of the data
1186 *
1187 * mode - the file permissions for the /proc/sys file
1188 *
1189 * child - must be %NULL.
1190 *
1191 * proc_handler - the text handler routine (described below)
1192 *
1193 * extra1, extra2 - extra pointers usable by the proc handler routines
1194 *
1195 * Leaf nodes in the sysctl tree will be represented by a single file
1196 * under /proc; non-leaf nodes will be represented by directories.
1197 *
1198 * There must be a proc_handler routine for any terminal nodes.
1199 * Several default handlers are available to cover common cases -
1200 *
1201 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1202 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1203 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1204 *
1205 * It is the handler's job to read the input buffer from user memory
1206 * and process it. The handler should return 0 on success.
1207 *
1208 * This routine returns %NULL on a failure to register, and a pointer
1209 * to the table header on success.
1210 */
1211struct ctl_table_header *__register_sysctl_table(
1212 struct ctl_table_set *set,
1213 const char *path, struct ctl_table *table)
1214{
1215 struct ctl_table_root *root = set->dir.header.root;
1216 struct ctl_table_header *header;
1217 const char *name, *nextname;
1218 struct ctl_dir *dir;
1219 struct ctl_table *entry;
1220 struct ctl_node *node;
1221 int nr_entries = 0;
1222
1223 for (entry = table; entry->procname; entry++)
1224 nr_entries++;
1225
1226 header = kzalloc(sizeof(struct ctl_table_header) +
1227 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1228 if (!header)
1229 return NULL;
1230
1231 node = (struct ctl_node *)(header + 1);
1232 init_header(header, root, set, node, table);
1233 if (sysctl_check_table(path, table))
1234 goto fail;
1235
1236 spin_lock(&sysctl_lock);
1237 dir = &set->dir;
1238 /* Reference moved down the diretory tree get_subdir */
1239 dir->header.nreg++;
1240 spin_unlock(&sysctl_lock);
1241
1242 /* Find the directory for the ctl_table */
1243 for (name = path; name; name = nextname) {
1244 int namelen;
1245 nextname = strchr(name, '/');
1246 if (nextname) {
1247 namelen = nextname - name;
1248 nextname++;
1249 } else {
1250 namelen = strlen(name);
1251 }
1252 if (namelen == 0)
1253 continue;
1254
1255 dir = get_subdir(dir, name, namelen);
1256 if (IS_ERR(dir))
1257 goto fail;
1258 }
1259
1260 spin_lock(&sysctl_lock);
1261 if (insert_header(dir, header))
1262 goto fail_put_dir_locked;
1263
1264 drop_sysctl_table(&dir->header);
1265 spin_unlock(&sysctl_lock);
1266
1267 return header;
1268
1269fail_put_dir_locked:
1270 drop_sysctl_table(&dir->header);
1271 spin_unlock(&sysctl_lock);
1272fail:
1273 kfree(header);
1274 dump_stack();
1275 return NULL;
1276}
1277
1278/**
1279 * register_sysctl - register a sysctl table
1280 * @path: The path to the directory the sysctl table is in.
1281 * @table: the table structure
1282 *
1283 * Register a sysctl table. @table should be a filled in ctl_table
1284 * array. A completely 0 filled entry terminates the table.
1285 *
1286 * See __register_sysctl_table for more details.
1287 */
1288struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1289{
1290 return __register_sysctl_table(&sysctl_table_root.default_set,
1291 path, table);
1292}
1293EXPORT_SYMBOL(register_sysctl);
1294
1295static char *append_path(const char *path, char *pos, const char *name)
1296{
1297 int namelen;
1298 namelen = strlen(name);
1299 if (((pos - path) + namelen + 2) >= PATH_MAX)
1300 return NULL;
1301 memcpy(pos, name, namelen);
1302 pos[namelen] = '/';
1303 pos[namelen + 1] = '\0';
1304 pos += namelen + 1;
1305 return pos;
1306}
1307
1308static int count_subheaders(struct ctl_table *table)
1309{
1310 int has_files = 0;
1311 int nr_subheaders = 0;
1312 struct ctl_table *entry;
1313
1314 /* special case: no directory and empty directory */
1315 if (!table || !table->procname)
1316 return 1;
1317
1318 for (entry = table; entry->procname; entry++) {
1319 if (entry->child)
1320 nr_subheaders += count_subheaders(entry->child);
1321 else
1322 has_files = 1;
1323 }
1324 return nr_subheaders + has_files;
1325}
1326
1327static int register_leaf_sysctl_tables(const char *path, char *pos,
1328 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1329 struct ctl_table *table)
1330{
1331 struct ctl_table *ctl_table_arg = NULL;
1332 struct ctl_table *entry, *files;
1333 int nr_files = 0;
1334 int nr_dirs = 0;
1335 int err = -ENOMEM;
1336
1337 for (entry = table; entry->procname; entry++) {
1338 if (entry->child)
1339 nr_dirs++;
1340 else
1341 nr_files++;
1342 }
1343
1344 files = table;
1345 /* If there are mixed files and directories we need a new table */
1346 if (nr_dirs && nr_files) {
1347 struct ctl_table *new;
1348 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1349 GFP_KERNEL);
1350 if (!files)
1351 goto out;
1352
1353 ctl_table_arg = files;
1354 for (new = files, entry = table; entry->procname; entry++) {
1355 if (entry->child)
1356 continue;
1357 *new = *entry;
1358 new++;
1359 }
1360 }
1361
1362 /* Register everything except a directory full of subdirectories */
1363 if (nr_files || !nr_dirs) {
1364 struct ctl_table_header *header;
1365 header = __register_sysctl_table(set, path, files);
1366 if (!header) {
1367 kfree(ctl_table_arg);
1368 goto out;
1369 }
1370
1371 /* Remember if we need to free the file table */
1372 header->ctl_table_arg = ctl_table_arg;
1373 **subheader = header;
1374 (*subheader)++;
1375 }
1376
1377 /* Recurse into the subdirectories. */
1378 for (entry = table; entry->procname; entry++) {
1379 char *child_pos;
1380
1381 if (!entry->child)
1382 continue;
1383
1384 err = -ENAMETOOLONG;
1385 child_pos = append_path(path, pos, entry->procname);
1386 if (!child_pos)
1387 goto out;
1388
1389 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1390 set, entry->child);
1391 pos[0] = '\0';
1392 if (err)
1393 goto out;
1394 }
1395 err = 0;
1396out:
1397 /* On failure our caller will unregister all registered subheaders */
1398 return err;
1399}
1400
1401/**
1402 * __register_sysctl_paths - register a sysctl table hierarchy
1403 * @set: Sysctl tree to register on
1404 * @path: The path to the directory the sysctl table is in.
1405 * @table: the top-level table structure
1406 *
1407 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1408 * array. A completely 0 filled entry terminates the table.
1409 *
1410 * See __register_sysctl_table for more details.
1411 */
1412struct ctl_table_header *__register_sysctl_paths(
1413 struct ctl_table_set *set,
1414 const struct ctl_path *path, struct ctl_table *table)
1415{
1416 struct ctl_table *ctl_table_arg = table;
1417 int nr_subheaders = count_subheaders(table);
1418 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1419 const struct ctl_path *component;
1420 char *new_path, *pos;
1421
1422 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1423 if (!new_path)
1424 return NULL;
1425
1426 pos[0] = '\0';
1427 for (component = path; component->procname; component++) {
1428 pos = append_path(new_path, pos, component->procname);
1429 if (!pos)
1430 goto out;
1431 }
1432 while (table->procname && table->child && !table[1].procname) {
1433 pos = append_path(new_path, pos, table->procname);
1434 if (!pos)
1435 goto out;
1436 table = table->child;
1437 }
1438 if (nr_subheaders == 1) {
1439 header = __register_sysctl_table(set, new_path, table);
1440 if (header)
1441 header->ctl_table_arg = ctl_table_arg;
1442 } else {
1443 header = kzalloc(sizeof(*header) +
1444 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1445 if (!header)
1446 goto out;
1447
1448 subheaders = (struct ctl_table_header **) (header + 1);
1449 subheader = subheaders;
1450 header->ctl_table_arg = ctl_table_arg;
1451
1452 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1453 set, table))
1454 goto err_register_leaves;
1455 }
1456
1457out:
1458 kfree(new_path);
1459 return header;
1460
1461err_register_leaves:
1462 while (subheader > subheaders) {
1463 struct ctl_table_header *subh = *(--subheader);
1464 struct ctl_table *table = subh->ctl_table_arg;
1465 unregister_sysctl_table(subh);
1466 kfree(table);
1467 }
1468 kfree(header);
1469 header = NULL;
1470 goto out;
1471}
1472
1473/**
1474 * register_sysctl_table_path - register a sysctl table hierarchy
1475 * @path: The path to the directory the sysctl table is in.
1476 * @table: the top-level table structure
1477 *
1478 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1479 * array. A completely 0 filled entry terminates the table.
1480 *
1481 * See __register_sysctl_paths for more details.
1482 */
1483struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1484 struct ctl_table *table)
1485{
1486 return __register_sysctl_paths(&sysctl_table_root.default_set,
1487 path, table);
1488}
1489EXPORT_SYMBOL(register_sysctl_paths);
1490
1491/**
1492 * register_sysctl_table - register a sysctl table hierarchy
1493 * @table: the top-level table structure
1494 *
1495 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1496 * array. A completely 0 filled entry terminates the table.
1497 *
1498 * See register_sysctl_paths for more details.
1499 */
1500struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1501{
1502 static const struct ctl_path null_path[] = { {} };
1503
1504 return register_sysctl_paths(null_path, table);
1505}
1506EXPORT_SYMBOL(register_sysctl_table);
1507
1508static void put_links(struct ctl_table_header *header)
1509{
1510 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1511 struct ctl_table_root *root = header->root;
1512 struct ctl_dir *parent = header->parent;
1513 struct ctl_dir *core_parent;
1514 struct ctl_table *entry;
1515
1516 if (header->set == root_set)
1517 return;
1518
1519 core_parent = xlate_dir(root_set, parent);
1520 if (IS_ERR(core_parent))
1521 return;
1522
1523 for (entry = header->ctl_table; entry->procname; entry++) {
1524 struct ctl_table_header *link_head;
1525 struct ctl_table *link;
1526 const char *name = entry->procname;
1527
1528 link = find_entry(&link_head, core_parent, name, strlen(name));
1529 if (link &&
1530 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1531 (S_ISLNK(link->mode) && (link->data == root)))) {
1532 drop_sysctl_table(link_head);
1533 }
1534 else {
1535 pr_err("sysctl link missing during unregister: ");
1536 sysctl_print_dir(parent);
1537 pr_cont("/%s\n", name);
1538 }
1539 }
1540}
1541
1542static void drop_sysctl_table(struct ctl_table_header *header)
1543{
1544 struct ctl_dir *parent = header->parent;
1545
1546 if (--header->nreg)
1547 return;
1548
1549 put_links(header);
1550 start_unregistering(header);
1551 if (!--header->count)
1552 kfree_rcu(header, rcu);
1553
1554 if (parent)
1555 drop_sysctl_table(&parent->header);
1556}
1557
1558/**
1559 * unregister_sysctl_table - unregister a sysctl table hierarchy
1560 * @header: the header returned from register_sysctl_table
1561 *
1562 * Unregisters the sysctl table and all children. proc entries may not
1563 * actually be removed until they are no longer used by anyone.
1564 */
1565void unregister_sysctl_table(struct ctl_table_header * header)
1566{
1567 int nr_subheaders;
1568 might_sleep();
1569
1570 if (header == NULL)
1571 return;
1572
1573 nr_subheaders = count_subheaders(header->ctl_table_arg);
1574 if (unlikely(nr_subheaders > 1)) {
1575 struct ctl_table_header **subheaders;
1576 int i;
1577
1578 subheaders = (struct ctl_table_header **)(header + 1);
1579 for (i = nr_subheaders -1; i >= 0; i--) {
1580 struct ctl_table_header *subh = subheaders[i];
1581 struct ctl_table *table = subh->ctl_table_arg;
1582 unregister_sysctl_table(subh);
1583 kfree(table);
1584 }
1585 kfree(header);
1586 return;
1587 }
1588
1589 spin_lock(&sysctl_lock);
1590 drop_sysctl_table(header);
1591 spin_unlock(&sysctl_lock);
1592}
1593EXPORT_SYMBOL(unregister_sysctl_table);
1594
1595void setup_sysctl_set(struct ctl_table_set *set,
1596 struct ctl_table_root *root,
1597 int (*is_seen)(struct ctl_table_set *))
1598{
1599 memset(set, 0, sizeof(*set));
1600 set->is_seen = is_seen;
1601 init_header(&set->dir.header, root, set, NULL, root_table);
1602}
1603
1604void retire_sysctl_set(struct ctl_table_set *set)
1605{
1606 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1607}
1608
1609int __init proc_sys_init(void)
1610{
1611 struct proc_dir_entry *proc_sys_root;
1612
1613 proc_sys_root = proc_mkdir("sys", NULL);
1614 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1615 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1616 proc_sys_root->nlink = 0;
1617
1618 return sysctl_init();
1619}
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
15static const struct dentry_operations proc_sys_dentry_operations;
16static const struct file_operations proc_sys_file_operations;
17static const struct inode_operations proc_sys_inode_operations;
18static const struct file_operations proc_sys_dir_file_operations;
19static const struct inode_operations proc_sys_dir_operations;
20
21void 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
30static struct ctl_table root_table[] = {
31 {
32 .procname = "",
33 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
34 },
35 { }
36};
37static 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
48static DEFINE_SPINLOCK(sysctl_lock);
49
50static void drop_sysctl_table(struct ctl_table_header *header);
51static int sysctl_follow_link(struct ctl_table_header **phead,
52 struct ctl_table **pentry, struct nsproxy *namespaces);
53static int insert_links(struct ctl_table_header *head);
54static void put_links(struct ctl_table_header *header);
55
56static 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
63static 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 */
79static 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
110static 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
148static 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
155static 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
178static 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
185static 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;
201fail:
202 erase_header(header);
203 put_links(header);
204fail_links:
205 header->parent = NULL;
206 drop_sysctl_table(&dir->header);
207 return err;
208}
209
210/* called under sysctl_lock */
211static 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 */
220static 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 */
228static 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
252static 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
259void 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
267static 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
278static 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
287static struct ctl_table_set *
288lookup_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
296static 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
313static 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
325static 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
343static 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
363void 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
372static 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
383static 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
395static 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 }
423out:
424 return inode;
425}
426
427static 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
435static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
436 struct nameidata *nd)
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
472out:
473 if (h)
474 sysctl_head_finish(h);
475 sysctl_head_finish(head);
476 return err;
477}
478
479static 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;
509out:
510 sysctl_head_finish(head);
511
512 return error;
513}
514
515static 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
521static 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
527static 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
544static 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
570out:
571 sysctl_head_finish(head);
572
573 return ret;
574}
575
576static 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
614static 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);
630out:
631 sysctl_head_finish(head);
632 return ret;
633}
634
635static 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
655static 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;
695out:
696 sysctl_head_finish(head);
697 return ret;
698}
699
700static 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
728static 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
752static 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
769static 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
777static 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
783static 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
789static 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
796static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
797{
798 if (nd->flags & LOOKUP_RCU)
799 return -ECHILD;
800 return !PROC_I(dentry->d_inode)->sysctl->unregistering;
801}
802
803static int proc_sys_delete(const struct dentry *dentry)
804{
805 return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
806}
807
808static 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
823static 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
842static 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
848static 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
862static 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 */
900static 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;
934found:
935 subdir->header.nreg++;
936failed:
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
950static 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
963static 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
997static 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
1013static 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
1043static 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
1086static 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
1114static 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);
1150out:
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 */
1197struct 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
1255fail_put_dir_locked:
1256 drop_sysctl_table(&dir->header);
1257 spin_unlock(&sysctl_lock);
1258fail:
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 */
1274struct 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}
1279EXPORT_SYMBOL(register_sysctl);
1280
1281static 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
1294static 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
1313static 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;
1382out:
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 */
1398struct 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
1443out:
1444 kfree(new_path);
1445 return header;
1446
1447err_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 */
1469struct 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}
1475EXPORT_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 */
1486struct 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}
1492EXPORT_SYMBOL(register_sysctl_table);
1493
1494static 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
1528static 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 */
1551void 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}
1579EXPORT_SYMBOL(unregister_sysctl_table);
1580
1581void 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
1590void retire_sysctl_set(struct ctl_table_set *set)
1591{
1592 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1593}
1594
1595int __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}