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mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race
[linux/fpc-iii.git] / fs / proc / proc_sysctl.c
blob12bac452738df3dc3e593fe01cadb94a03470eac
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * /proc/sys support
4 */
5 #include <linux/init.h>
6 #include <linux/sysctl.h>
7 #include <linux/poll.h>
8 #include <linux/proc_fs.h>
9 #include <linux/printk.h>
10 #include <linux/security.h>
11 #include <linux/sched.h>
12 #include <linux/cred.h>
13 #include <linux/namei.h>
14 #include <linux/mm.h>
15 #include <linux/module.h>
16 #include "internal.h"
17
18 static const struct dentry_operations proc_sys_dentry_operations;
19 static const struct file_operations proc_sys_file_operations;
20 static const struct inode_operations proc_sys_inode_operations;
21 static const struct file_operations proc_sys_dir_file_operations;
22 static const struct inode_operations proc_sys_dir_operations;
23
24 /* Support for permanently empty directories */
25
26 struct ctl_table sysctl_mount_point[] = {
27 { }
28 };
29
30 static bool is_empty_dir(struct ctl_table_header *head)
31 {
32 return head->ctl_table[0].child == sysctl_mount_point;
33 }
34
35 static void set_empty_dir(struct ctl_dir *dir)
36 {
37 dir->header.ctl_table[0].child = sysctl_mount_point;
38 }
39
40 static void clear_empty_dir(struct ctl_dir *dir)
41
42 {
43 dir->header.ctl_table[0].child = NULL;
44 }
45
46 void proc_sys_poll_notify(struct ctl_table_poll *poll)
47 {
48 if (!poll)
49 return;
50
51 atomic_inc(&poll->event);
52 wake_up_interruptible(&poll->wait);
53 }
54
55 static struct ctl_table root_table[] = {
56 {
57 .procname = "",
58 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
59 },
60 { }
61 };
62 static struct ctl_table_root sysctl_table_root = {
63 .default_set.dir.header = {
64 {{.count = 1,
65 .nreg = 1,
66 .ctl_table = root_table }},
67 .ctl_table_arg = root_table,
68 .root = &sysctl_table_root,
69 .set = &sysctl_table_root.default_set,
70 },
71 };
72
73 static DEFINE_SPINLOCK(sysctl_lock);
74
75 static void drop_sysctl_table(struct ctl_table_header *header);
76 static int sysctl_follow_link(struct ctl_table_header **phead,
77 struct ctl_table **pentry);
78 static int insert_links(struct ctl_table_header *head);
79 static void put_links(struct ctl_table_header *header);
80
81 static void sysctl_print_dir(struct ctl_dir *dir)
82 {
83 if (dir->header.parent)
84 sysctl_print_dir(dir->header.parent);
85 pr_cont("%s/", dir->header.ctl_table[0].procname);
86 }
87
88 static int namecmp(const char *name1, int len1, const char *name2, int len2)
89 {
90 int minlen;
91 int cmp;
92
93 minlen = len1;
94 if (minlen > len2)
95 minlen = len2;
96
97 cmp = memcmp(name1, name2, minlen);
98 if (cmp == 0)
99 cmp = len1 - len2;
100 return cmp;
101 }
102
103 /* Called under sysctl_lock */
104 static struct ctl_table *find_entry(struct ctl_table_header **phead,
105 struct ctl_dir *dir, const char *name, int namelen)
106 {
107 struct ctl_table_header *head;
108 struct ctl_table *entry;
109 struct rb_node *node = dir->root.rb_node;
110
111 while (node)
112 {
113 struct ctl_node *ctl_node;
114 const char *procname;
115 int cmp;
116
117 ctl_node = rb_entry(node, struct ctl_node, node);
118 head = ctl_node->header;
119 entry = &head->ctl_table[ctl_node - head->node];
120 procname = entry->procname;
121
122 cmp = namecmp(name, namelen, procname, strlen(procname));
123 if (cmp < 0)
124 node = node->rb_left;
125 else if (cmp > 0)
126 node = node->rb_right;
127 else {
128 *phead = head;
129 return entry;
130 }
131 }
132 return NULL;
133 }
134
135 static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
136 {
137 struct rb_node *node = &head->node[entry - head->ctl_table].node;
138 struct rb_node **p = &head->parent->root.rb_node;
139 struct rb_node *parent = NULL;
140 const char *name = entry->procname;
141 int namelen = strlen(name);
142
143 while (*p) {
144 struct ctl_table_header *parent_head;
145 struct ctl_table *parent_entry;
146 struct ctl_node *parent_node;
147 const char *parent_name;
148 int cmp;
149
150 parent = *p;
151 parent_node = rb_entry(parent, struct ctl_node, node);
152 parent_head = parent_node->header;
153 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
154 parent_name = parent_entry->procname;
155
156 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
157 if (cmp < 0)
158 p = &(*p)->rb_left;
159 else if (cmp > 0)
160 p = &(*p)->rb_right;
161 else {
162 pr_err("sysctl duplicate entry: ");
163 sysctl_print_dir(head->parent);
164 pr_cont("/%s\n", entry->procname);
165 return -EEXIST;
166 }
167 }
168
169 rb_link_node(node, parent, p);
170 rb_insert_color(node, &head->parent->root);
171 return 0;
172 }
173
174 static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
175 {
176 struct rb_node *node = &head->node[entry - head->ctl_table].node;
177
178 rb_erase(node, &head->parent->root);
179 }
180
181 static void init_header(struct ctl_table_header *head,
182 struct ctl_table_root *root, struct ctl_table_set *set,
183 struct ctl_node *node, struct ctl_table *table)
184 {
185 head->ctl_table = table;
186 head->ctl_table_arg = table;
187 head->used = 0;
188 head->count = 1;
189 head->nreg = 1;
190 head->unregistering = NULL;
191 head->root = root;
192 head->set = set;
193 head->parent = NULL;
194 head->node = node;
195 INIT_HLIST_HEAD(&head->inodes);
196 if (node) {
197 struct ctl_table *entry;
198 for (entry = table; entry->procname; entry++, node++)
199 node->header = head;
200 }
201 }
202
203 static void erase_header(struct ctl_table_header *head)
204 {
205 struct ctl_table *entry;
206 for (entry = head->ctl_table; entry->procname; entry++)
207 erase_entry(head, entry);
208 }
209
210 static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
211 {
212 struct ctl_table *entry;
213 int err;
214
215 /* Is this a permanently empty directory? */
216 if (is_empty_dir(&dir->header))
217 return -EROFS;
218
219 /* Am I creating a permanently empty directory? */
220 if (header->ctl_table == sysctl_mount_point) {
221 if (!RB_EMPTY_ROOT(&dir->root))
222 return -EINVAL;
223 set_empty_dir(dir);
224 }
225
226 dir->header.nreg++;
227 header->parent = dir;
228 err = insert_links(header);
229 if (err)
230 goto fail_links;
231 for (entry = header->ctl_table; entry->procname; entry++) {
232 err = insert_entry(header, entry);
233 if (err)
234 goto fail;
235 }
236 return 0;
237 fail:
238 erase_header(header);
239 put_links(header);
240 fail_links:
241 if (header->ctl_table == sysctl_mount_point)
242 clear_empty_dir(dir);
243 header->parent = NULL;
244 drop_sysctl_table(&dir->header);
245 return err;
246 }
247
248 /* called under sysctl_lock */
249 static int use_table(struct ctl_table_header *p)
250 {
251 if (unlikely(p->unregistering))
252 return 0;
253 p->used++;
254 return 1;
255 }
256
257 /* called under sysctl_lock */
258 static void unuse_table(struct ctl_table_header *p)
259 {
260 if (!--p->used)
261 if (unlikely(p->unregistering))
262 complete(p->unregistering);
263 }
264
265 static void proc_sys_prune_dcache(struct ctl_table_header *head)
266 {
267 struct inode *inode;
268 struct proc_inode *ei;
269 struct hlist_node *node;
270 struct super_block *sb;
271
272 rcu_read_lock();
273 for (;;) {
274 node = hlist_first_rcu(&head->inodes);
275 if (!node)
276 break;
277 ei = hlist_entry(node, struct proc_inode, sysctl_inodes);
278 spin_lock(&sysctl_lock);
279 hlist_del_init_rcu(&ei->sysctl_inodes);
280 spin_unlock(&sysctl_lock);
281
282 inode = &ei->vfs_inode;
283 sb = inode->i_sb;
284 if (!atomic_inc_not_zero(&sb->s_active))
285 continue;
286 inode = igrab(inode);
287 rcu_read_unlock();
288 if (unlikely(!inode)) {
289 deactivate_super(sb);
290 rcu_read_lock();
291 continue;
292 }
293
294 d_prune_aliases(inode);
295 iput(inode);
296 deactivate_super(sb);
297
298 rcu_read_lock();
299 }
300 rcu_read_unlock();
301 }
302
303 /* called under sysctl_lock, will reacquire if has to wait */
304 static void start_unregistering(struct ctl_table_header *p)
305 {
306 /*
307 * if p->used is 0, nobody will ever touch that entry again;
308 * we'll eliminate all paths to it before dropping sysctl_lock
309 */
310 if (unlikely(p->used)) {
311 struct completion wait;
312 init_completion(&wait);
313 p->unregistering = &wait;
314 spin_unlock(&sysctl_lock);
315 wait_for_completion(&wait);
316 } else {
317 /* anything non-NULL; we'll never dereference it */
318 p->unregistering = ERR_PTR(-EINVAL);
319 spin_unlock(&sysctl_lock);
320 }
321 /*
322 * Prune dentries for unregistered sysctls: namespaced sysctls
323 * can have duplicate names and contaminate dcache very badly.
324 */
325 proc_sys_prune_dcache(p);
326 /*
327 * do not remove from the list until nobody holds it; walking the
328 * list in do_sysctl() relies on that.
329 */
330 spin_lock(&sysctl_lock);
331 erase_header(p);
332 }
333
334 static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
335 {
336 BUG_ON(!head);
337 spin_lock(&sysctl_lock);
338 if (!use_table(head))
339 head = ERR_PTR(-ENOENT);
340 spin_unlock(&sysctl_lock);
341 return head;
342 }
343
344 static void sysctl_head_finish(struct ctl_table_header *head)
345 {
346 if (!head)
347 return;
348 spin_lock(&sysctl_lock);
349 unuse_table(head);
350 spin_unlock(&sysctl_lock);
351 }
352
353 static struct ctl_table_set *
354 lookup_header_set(struct ctl_table_root *root)
355 {
356 struct ctl_table_set *set = &root->default_set;
357 if (root->lookup)
358 set = root->lookup(root);
359 return set;
360 }
361
362 static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
363 struct ctl_dir *dir,
364 const char *name, int namelen)
365 {
366 struct ctl_table_header *head;
367 struct ctl_table *entry;
368
369 spin_lock(&sysctl_lock);
370 entry = find_entry(&head, dir, name, namelen);
371 if (entry && use_table(head))
372 *phead = head;
373 else
374 entry = NULL;
375 spin_unlock(&sysctl_lock);
376 return entry;
377 }
378
379 static struct ctl_node *first_usable_entry(struct rb_node *node)
380 {
381 struct ctl_node *ctl_node;
382
383 for (;node; node = rb_next(node)) {
384 ctl_node = rb_entry(node, struct ctl_node, node);
385 if (use_table(ctl_node->header))
386 return ctl_node;
387 }
388 return NULL;
389 }
390
391 static void first_entry(struct ctl_dir *dir,
392 struct ctl_table_header **phead, struct ctl_table **pentry)
393 {
394 struct ctl_table_header *head = NULL;
395 struct ctl_table *entry = NULL;
396 struct ctl_node *ctl_node;
397
398 spin_lock(&sysctl_lock);
399 ctl_node = first_usable_entry(rb_first(&dir->root));
400 spin_unlock(&sysctl_lock);
401 if (ctl_node) {
402 head = ctl_node->header;
403 entry = &head->ctl_table[ctl_node - head->node];
404 }
405 *phead = head;
406 *pentry = entry;
407 }
408
409 static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
410 {
411 struct ctl_table_header *head = *phead;
412 struct ctl_table *entry = *pentry;
413 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
414
415 spin_lock(&sysctl_lock);
416 unuse_table(head);
417
418 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
419 spin_unlock(&sysctl_lock);
420 head = NULL;
421 if (ctl_node) {
422 head = ctl_node->header;
423 entry = &head->ctl_table[ctl_node - head->node];
424 }
425 *phead = head;
426 *pentry = entry;
427 }
428
429 /*
430 * sysctl_perm does NOT grant the superuser all rights automatically, because
431 * some sysctl variables are readonly even to root.
432 */
433
434 static int test_perm(int mode, int op)
435 {
436 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
437 mode >>= 6;
438 else if (in_egroup_p(GLOBAL_ROOT_GID))
439 mode >>= 3;
440 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
441 return 0;
442 return -EACCES;
443 }
444
445 static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
446 {
447 struct ctl_table_root *root = head->root;
448 int mode;
449
450 if (root->permissions)
451 mode = root->permissions(head, table);
452 else
453 mode = table->mode;
454
455 return test_perm(mode, op);
456 }
457
458 static struct inode *proc_sys_make_inode(struct super_block *sb,
459 struct ctl_table_header *head, struct ctl_table *table)
460 {
461 struct ctl_table_root *root = head->root;
462 struct inode *inode;
463 struct proc_inode *ei;
464
465 inode = new_inode(sb);
466 if (!inode)
467 return ERR_PTR(-ENOMEM);
468
469 inode->i_ino = get_next_ino();
470
471 ei = PROC_I(inode);
472
473 spin_lock(&sysctl_lock);
474 if (unlikely(head->unregistering)) {
475 spin_unlock(&sysctl_lock);
476 iput(inode);
477 return ERR_PTR(-ENOENT);
478 }
479 ei->sysctl = head;
480 ei->sysctl_entry = table;
481 hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes);
482 head->count++;
483 spin_unlock(&sysctl_lock);
484
485 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
486 inode->i_mode = table->mode;
487 if (!S_ISDIR(table->mode)) {
488 inode->i_mode |= S_IFREG;
489 inode->i_op = &proc_sys_inode_operations;
490 inode->i_fop = &proc_sys_file_operations;
491 } else {
492 inode->i_mode |= S_IFDIR;
493 inode->i_op = &proc_sys_dir_operations;
494 inode->i_fop = &proc_sys_dir_file_operations;
495 if (is_empty_dir(head))
496 make_empty_dir_inode(inode);
497 }
498
499 if (root->set_ownership)
500 root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
501 else {
502 inode->i_uid = GLOBAL_ROOT_UID;
503 inode->i_gid = GLOBAL_ROOT_GID;
504 }
505
506 return inode;
507 }
508
509 void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
510 {
511 spin_lock(&sysctl_lock);
512 hlist_del_init_rcu(&PROC_I(inode)->sysctl_inodes);
513 if (!--head->count)
514 kfree_rcu(head, rcu);
515 spin_unlock(&sysctl_lock);
516 }
517
518 static struct ctl_table_header *grab_header(struct inode *inode)
519 {
520 struct ctl_table_header *head = PROC_I(inode)->sysctl;
521 if (!head)
522 head = &sysctl_table_root.default_set.dir.header;
523 return sysctl_head_grab(head);
524 }
525
526 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
527 unsigned int flags)
528 {
529 struct ctl_table_header *head = grab_header(dir);
530 struct ctl_table_header *h = NULL;
531 const struct qstr *name = &dentry->d_name;
532 struct ctl_table *p;
533 struct inode *inode;
534 struct dentry *err = ERR_PTR(-ENOENT);
535 struct ctl_dir *ctl_dir;
536 int ret;
537
538 if (IS_ERR(head))
539 return ERR_CAST(head);
540
541 ctl_dir = container_of(head, struct ctl_dir, header);
542
543 p = lookup_entry(&h, ctl_dir, name->name, name->len);
544 if (!p)
545 goto out;
546
547 if (S_ISLNK(p->mode)) {
548 ret = sysctl_follow_link(&h, &p);
549 err = ERR_PTR(ret);
550 if (ret)
551 goto out;
552 }
553
554 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
555 if (IS_ERR(inode)) {
556 err = ERR_CAST(inode);
557 goto out;
558 }
559
560 err = NULL;
561 d_set_d_op(dentry, &proc_sys_dentry_operations);
562 d_add(dentry, inode);
563
564 out:
565 if (h)
566 sysctl_head_finish(h);
567 sysctl_head_finish(head);
568 return err;
569 }
570
571 static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
572 size_t count, loff_t *ppos, int write)
573 {
574 struct inode *inode = file_inode(filp);
575 struct ctl_table_header *head = grab_header(inode);
576 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
577 ssize_t error;
578 size_t res;
579
580 if (IS_ERR(head))
581 return PTR_ERR(head);
582
583 /*
584 * At this point we know that the sysctl was not unregistered
585 * and won't be until we finish.
586 */
587 error = -EPERM;
588 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
589 goto out;
590
591 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
592 error = -EINVAL;
593 if (!table->proc_handler)
594 goto out;
595
596 /* careful: calling conventions are nasty here */
597 res = count;
598 error = table->proc_handler(table, write, buf, &res, ppos);
599 if (!error)
600 error = res;
601 out:
602 sysctl_head_finish(head);
603
604 return error;
605 }
606
607 static ssize_t proc_sys_read(struct file *filp, char __user *buf,
608 size_t count, loff_t *ppos)
609 {
610 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
611 }
612
613 static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
614 size_t count, loff_t *ppos)
615 {
616 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
617 }
618
619 static int proc_sys_open(struct inode *inode, struct file *filp)
620 {
621 struct ctl_table_header *head = grab_header(inode);
622 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
623
624 /* sysctl was unregistered */
625 if (IS_ERR(head))
626 return PTR_ERR(head);
627
628 if (table->poll)
629 filp->private_data = proc_sys_poll_event(table->poll);
630
631 sysctl_head_finish(head);
632
633 return 0;
634 }
635
636 static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
637 {
638 struct inode *inode = file_inode(filp);
639 struct ctl_table_header *head = grab_header(inode);
640 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
641 unsigned int ret = DEFAULT_POLLMASK;
642 unsigned long event;
643
644 /* sysctl was unregistered */
645 if (IS_ERR(head))
646 return POLLERR | POLLHUP;
647
648 if (!table->proc_handler)
649 goto out;
650
651 if (!table->poll)
652 goto out;
653
654 event = (unsigned long)filp->private_data;
655 poll_wait(filp, &table->poll->wait, wait);
656
657 if (event != atomic_read(&table->poll->event)) {
658 filp->private_data = proc_sys_poll_event(table->poll);
659 ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI;
660 }
661
662 out:
663 sysctl_head_finish(head);
664
665 return ret;
666 }
667
668 static bool proc_sys_fill_cache(struct file *file,
669 struct dir_context *ctx,
670 struct ctl_table_header *head,
671 struct ctl_table *table)
672 {
673 struct dentry *child, *dir = file->f_path.dentry;
674 struct inode *inode;
675 struct qstr qname;
676 ino_t ino = 0;
677 unsigned type = DT_UNKNOWN;
678
679 qname.name = table->procname;
680 qname.len = strlen(table->procname);
681 qname.hash = full_name_hash(dir, qname.name, qname.len);
682
683 child = d_lookup(dir, &qname);
684 if (!child) {
685 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
686 child = d_alloc_parallel(dir, &qname, &wq);
687 if (IS_ERR(child))
688 return false;
689 if (d_in_lookup(child)) {
690 inode = proc_sys_make_inode(dir->d_sb, head, table);
691 if (IS_ERR(inode)) {
692 d_lookup_done(child);
693 dput(child);
694 return false;
695 }
696 d_set_d_op(child, &proc_sys_dentry_operations);
697 d_add(child, inode);
698 }
699 }
700 inode = d_inode(child);
701 ino = inode->i_ino;
702 type = inode->i_mode >> 12;
703 dput(child);
704 return dir_emit(ctx, qname.name, qname.len, ino, type);
705 }
706
707 static bool proc_sys_link_fill_cache(struct file *file,
708 struct dir_context *ctx,
709 struct ctl_table_header *head,
710 struct ctl_table *table)
711 {
712 bool ret = true;
713
714 head = sysctl_head_grab(head);
715 if (IS_ERR(head))
716 return false;
717
718 if (S_ISLNK(table->mode)) {
719 /* It is not an error if we can not follow the link ignore it */
720 int err = sysctl_follow_link(&head, &table);
721 if (err)
722 goto out;
723 }
724
725 ret = proc_sys_fill_cache(file, ctx, head, table);
726 out:
727 sysctl_head_finish(head);
728 return ret;
729 }
730
731 static int scan(struct ctl_table_header *head, struct ctl_table *table,
732 unsigned long *pos, struct file *file,
733 struct dir_context *ctx)
734 {
735 bool res;
736
737 if ((*pos)++ < ctx->pos)
738 return true;
739
740 if (unlikely(S_ISLNK(table->mode)))
741 res = proc_sys_link_fill_cache(file, ctx, head, table);
742 else
743 res = proc_sys_fill_cache(file, ctx, head, table);
744
745 if (res)
746 ctx->pos = *pos;
747
748 return res;
749 }
750
751 static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
752 {
753 struct ctl_table_header *head = grab_header(file_inode(file));
754 struct ctl_table_header *h = NULL;
755 struct ctl_table *entry;
756 struct ctl_dir *ctl_dir;
757 unsigned long pos;
758
759 if (IS_ERR(head))
760 return PTR_ERR(head);
761
762 ctl_dir = container_of(head, struct ctl_dir, header);
763
764 if (!dir_emit_dots(file, ctx))
765 goto out;
766
767 pos = 2;
768
769 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
770 if (!scan(h, entry, &pos, file, ctx)) {
771 sysctl_head_finish(h);
772 break;
773 }
774 }
775 out:
776 sysctl_head_finish(head);
777 return 0;
778 }
779
780 static int proc_sys_permission(struct inode *inode, int mask)
781 {
782 /*
783 * sysctl entries that are not writeable,
784 * are _NOT_ writeable, capabilities or not.
785 */
786 struct ctl_table_header *head;
787 struct ctl_table *table;
788 int error;
789
790 /* Executable files are not allowed under /proc/sys/ */
791 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
792 return -EACCES;
793
794 head = grab_header(inode);
795 if (IS_ERR(head))
796 return PTR_ERR(head);
797
798 table = PROC_I(inode)->sysctl_entry;
799 if (!table) /* global root - r-xr-xr-x */
800 error = mask & MAY_WRITE ? -EACCES : 0;
801 else /* Use the permissions on the sysctl table entry */
802 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
803
804 sysctl_head_finish(head);
805 return error;
806 }
807
808 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
809 {
810 struct inode *inode = d_inode(dentry);
811 int error;
812
813 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
814 return -EPERM;
815
816 error = setattr_prepare(dentry, attr);
817 if (error)
818 return error;
819
820 setattr_copy(inode, attr);
821 mark_inode_dirty(inode);
822 return 0;
823 }
824
825 static int proc_sys_getattr(const struct path *path, struct kstat *stat,
826 u32 request_mask, unsigned int query_flags)
827 {
828 struct inode *inode = d_inode(path->dentry);
829 struct ctl_table_header *head = grab_header(inode);
830 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
831
832 if (IS_ERR(head))
833 return PTR_ERR(head);
834
835 generic_fillattr(inode, stat);
836 if (table)
837 stat->mode = (stat->mode & S_IFMT) | table->mode;
838
839 sysctl_head_finish(head);
840 return 0;
841 }
842
843 static const struct file_operations proc_sys_file_operations = {
844 .open = proc_sys_open,
845 .poll = proc_sys_poll,
846 .read = proc_sys_read,
847 .write = proc_sys_write,
848 .llseek = default_llseek,
849 };
850
851 static const struct file_operations proc_sys_dir_file_operations = {
852 .read = generic_read_dir,
853 .iterate_shared = proc_sys_readdir,
854 .llseek = generic_file_llseek,
855 };
856
857 static const struct inode_operations proc_sys_inode_operations = {
858 .permission = proc_sys_permission,
859 .setattr = proc_sys_setattr,
860 .getattr = proc_sys_getattr,
861 };
862
863 static const struct inode_operations proc_sys_dir_operations = {
864 .lookup = proc_sys_lookup,
865 .permission = proc_sys_permission,
866 .setattr = proc_sys_setattr,
867 .getattr = proc_sys_getattr,
868 };
869
870 static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
871 {
872 if (flags & LOOKUP_RCU)
873 return -ECHILD;
874 return !PROC_I(d_inode(dentry))->sysctl->unregistering;
875 }
876
877 static int proc_sys_delete(const struct dentry *dentry)
878 {
879 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
880 }
881
882 static int sysctl_is_seen(struct ctl_table_header *p)
883 {
884 struct ctl_table_set *set = p->set;
885 int res;
886 spin_lock(&sysctl_lock);
887 if (p->unregistering)
888 res = 0;
889 else if (!set->is_seen)
890 res = 1;
891 else
892 res = set->is_seen(set);
893 spin_unlock(&sysctl_lock);
894 return res;
895 }
896
897 static int proc_sys_compare(const struct dentry *dentry,
898 unsigned int len, const char *str, const struct qstr *name)
899 {
900 struct ctl_table_header *head;
901 struct inode *inode;
902
903 /* Although proc doesn't have negative dentries, rcu-walk means
904 * that inode here can be NULL */
905 /* AV: can it, indeed? */
906 inode = d_inode_rcu(dentry);
907 if (!inode)
908 return 1;
909 if (name->len != len)
910 return 1;
911 if (memcmp(name->name, str, len))
912 return 1;
913 head = rcu_dereference(PROC_I(inode)->sysctl);
914 return !head || !sysctl_is_seen(head);
915 }
916
917 static const struct dentry_operations proc_sys_dentry_operations = {
918 .d_revalidate = proc_sys_revalidate,
919 .d_delete = proc_sys_delete,
920 .d_compare = proc_sys_compare,
921 };
922
923 static struct ctl_dir *find_subdir(struct ctl_dir *dir,
924 const char *name, int namelen)
925 {
926 struct ctl_table_header *head;
927 struct ctl_table *entry;
928
929 entry = find_entry(&head, dir, name, namelen);
930 if (!entry)
931 return ERR_PTR(-ENOENT);
932 if (!S_ISDIR(entry->mode))
933 return ERR_PTR(-ENOTDIR);
934 return container_of(head, struct ctl_dir, header);
935 }
936
937 static struct ctl_dir *new_dir(struct ctl_table_set *set,
938 const char *name, int namelen)
939 {
940 struct ctl_table *table;
941 struct ctl_dir *new;
942 struct ctl_node *node;
943 char *new_name;
944
945 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
946 sizeof(struct ctl_table)*2 + namelen + 1,
947 GFP_KERNEL);
948 if (!new)
949 return NULL;
950
951 node = (struct ctl_node *)(new + 1);
952 table = (struct ctl_table *)(node + 1);
953 new_name = (char *)(table + 2);
954 memcpy(new_name, name, namelen);
955 new_name[namelen] = '\0';
956 table[0].procname = new_name;
957 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
958 init_header(&new->header, set->dir.header.root, set, node, table);
959
960 return new;
961 }
962
963 /**
964 * get_subdir - find or create a subdir with the specified name.
965 * @dir: Directory to create the subdirectory in
966 * @name: The name of the subdirectory to find or create
967 * @namelen: The length of name
968 *
969 * Takes a directory with an elevated reference count so we know that
970 * if we drop the lock the directory will not go away. Upon success
971 * the reference is moved from @dir to the returned subdirectory.
972 * Upon error an error code is returned and the reference on @dir is
973 * simply dropped.
974 */
975 static struct ctl_dir *get_subdir(struct ctl_dir *dir,
976 const char *name, int namelen)
977 {
978 struct ctl_table_set *set = dir->header.set;
979 struct ctl_dir *subdir, *new = NULL;
980 int err;
981
982 spin_lock(&sysctl_lock);
983 subdir = find_subdir(dir, name, namelen);
984 if (!IS_ERR(subdir))
985 goto found;
986 if (PTR_ERR(subdir) != -ENOENT)
987 goto failed;
988
989 spin_unlock(&sysctl_lock);
990 new = new_dir(set, name, namelen);
991 spin_lock(&sysctl_lock);
992 subdir = ERR_PTR(-ENOMEM);
993 if (!new)
994 goto failed;
995
996 /* Was the subdir added while we dropped the lock? */
997 subdir = find_subdir(dir, name, namelen);
998 if (!IS_ERR(subdir))
999 goto found;
1000 if (PTR_ERR(subdir) != -ENOENT)
1001 goto failed;
1002
1003 /* Nope. Use the our freshly made directory entry. */
1004 err = insert_header(dir, &new->header);
1005 subdir = ERR_PTR(err);
1006 if (err)
1007 goto failed;
1008 subdir = new;
1009 found:
1010 subdir->header.nreg++;
1011 failed:
1012 if (IS_ERR(subdir)) {
1013 pr_err("sysctl could not get directory: ");
1014 sysctl_print_dir(dir);
1015 pr_cont("/%*.*s %ld\n",
1016 namelen, namelen, name, PTR_ERR(subdir));
1017 }
1018 drop_sysctl_table(&dir->header);
1019 if (new)
1020 drop_sysctl_table(&new->header);
1021 spin_unlock(&sysctl_lock);
1022 return subdir;
1023 }
1024
1025 static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
1026 {
1027 struct ctl_dir *parent;
1028 const char *procname;
1029 if (!dir->header.parent)
1030 return &set->dir;
1031 parent = xlate_dir(set, dir->header.parent);
1032 if (IS_ERR(parent))
1033 return parent;
1034 procname = dir->header.ctl_table[0].procname;
1035 return find_subdir(parent, procname, strlen(procname));
1036 }
1037
1038 static int sysctl_follow_link(struct ctl_table_header **phead,
1039 struct ctl_table **pentry)
1040 {
1041 struct ctl_table_header *head;
1042 struct ctl_table_root *root;
1043 struct ctl_table_set *set;
1044 struct ctl_table *entry;
1045 struct ctl_dir *dir;
1046 int ret;
1047
1048 ret = 0;
1049 spin_lock(&sysctl_lock);
1050 root = (*pentry)->data;
1051 set = lookup_header_set(root);
1052 dir = xlate_dir(set, (*phead)->parent);
1053 if (IS_ERR(dir))
1054 ret = PTR_ERR(dir);
1055 else {
1056 const char *procname = (*pentry)->procname;
1057 head = NULL;
1058 entry = find_entry(&head, dir, procname, strlen(procname));
1059 ret = -ENOENT;
1060 if (entry && use_table(head)) {
1061 unuse_table(*phead);
1062 *phead = head;
1063 *pentry = entry;
1064 ret = 0;
1065 }
1066 }
1067
1068 spin_unlock(&sysctl_lock);
1069 return ret;
1070 }
1071
1072 static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
1073 {
1074 struct va_format vaf;
1075 va_list args;
1076
1077 va_start(args, fmt);
1078 vaf.fmt = fmt;
1079 vaf.va = &args;
1080
1081 pr_err("sysctl table check failed: %s/%s %pV\n",
1082 path, table->procname, &vaf);
1083
1084 va_end(args);
1085 return -EINVAL;
1086 }
1087
1088 static int sysctl_check_table_array(const char *path, struct ctl_table *table)
1089 {
1090 int err = 0;
1091
1092 if ((table->proc_handler == proc_douintvec) ||
1093 (table->proc_handler == proc_douintvec_minmax)) {
1094 if (table->maxlen != sizeof(unsigned int))
1095 err |= sysctl_err(path, table, "array now allowed");
1096 }
1097
1098 return err;
1099 }
1100
1101 static int sysctl_check_table(const char *path, struct ctl_table *table)
1102 {
1103 int err = 0;
1104 for (; table->procname; table++) {
1105 if (table->child)
1106 err |= sysctl_err(path, table, "Not a file");
1107
1108 if ((table->proc_handler == proc_dostring) ||
1109 (table->proc_handler == proc_dointvec) ||
1110 (table->proc_handler == proc_douintvec) ||
1111 (table->proc_handler == proc_douintvec_minmax) ||
1112 (table->proc_handler == proc_dointvec_minmax) ||
1113 (table->proc_handler == proc_dointvec_jiffies) ||
1114 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1115 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1116 (table->proc_handler == proc_doulongvec_minmax) ||
1117 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1118 if (!table->data)
1119 err |= sysctl_err(path, table, "No data");
1120 if (!table->maxlen)
1121 err |= sysctl_err(path, table, "No maxlen");
1122 else
1123 err |= sysctl_check_table_array(path, table);
1124 }
1125 if (!table->proc_handler)
1126 err |= sysctl_err(path, table, "No proc_handler");
1127
1128 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1129 err |= sysctl_err(path, table, "bogus .mode 0%o",
1130 table->mode);
1131 }
1132 return err;
1133 }
1134
1135 static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1136 struct ctl_table_root *link_root)
1137 {
1138 struct ctl_table *link_table, *entry, *link;
1139 struct ctl_table_header *links;
1140 struct ctl_node *node;
1141 char *link_name;
1142 int nr_entries, name_bytes;
1143
1144 name_bytes = 0;
1145 nr_entries = 0;
1146 for (entry = table; entry->procname; entry++) {
1147 nr_entries++;
1148 name_bytes += strlen(entry->procname) + 1;
1149 }
1150
1151 links = kzalloc(sizeof(struct ctl_table_header) +
1152 sizeof(struct ctl_node)*nr_entries +
1153 sizeof(struct ctl_table)*(nr_entries + 1) +
1154 name_bytes,
1155 GFP_KERNEL);
1156
1157 if (!links)
1158 return NULL;
1159
1160 node = (struct ctl_node *)(links + 1);
1161 link_table = (struct ctl_table *)(node + nr_entries);
1162 link_name = (char *)&link_table[nr_entries + 1];
1163
1164 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1165 int len = strlen(entry->procname) + 1;
1166 memcpy(link_name, entry->procname, len);
1167 link->procname = link_name;
1168 link->mode = S_IFLNK|S_IRWXUGO;
1169 link->data = link_root;
1170 link_name += len;
1171 }
1172 init_header(links, dir->header.root, dir->header.set, node, link_table);
1173 links->nreg = nr_entries;
1174
1175 return links;
1176 }
1177
1178 static bool get_links(struct ctl_dir *dir,
1179 struct ctl_table *table, struct ctl_table_root *link_root)
1180 {
1181 struct ctl_table_header *head;
1182 struct ctl_table *entry, *link;
1183
1184 /* Are there links available for every entry in table? */
1185 for (entry = table; entry->procname; entry++) {
1186 const char *procname = entry->procname;
1187 link = find_entry(&head, dir, procname, strlen(procname));
1188 if (!link)
1189 return false;
1190 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1191 continue;
1192 if (S_ISLNK(link->mode) && (link->data == link_root))
1193 continue;
1194 return false;
1195 }
1196
1197 /* The checks passed. Increase the registration count on the links */
1198 for (entry = table; entry->procname; entry++) {
1199 const char *procname = entry->procname;
1200 link = find_entry(&head, dir, procname, strlen(procname));
1201 head->nreg++;
1202 }
1203 return true;
1204 }
1205
1206 static int insert_links(struct ctl_table_header *head)
1207 {
1208 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1209 struct ctl_dir *core_parent = NULL;
1210 struct ctl_table_header *links;
1211 int err;
1212
1213 if (head->set == root_set)
1214 return 0;
1215
1216 core_parent = xlate_dir(root_set, head->parent);
1217 if (IS_ERR(core_parent))
1218 return 0;
1219
1220 if (get_links(core_parent, head->ctl_table, head->root))
1221 return 0;
1222
1223 core_parent->header.nreg++;
1224 spin_unlock(&sysctl_lock);
1225
1226 links = new_links(core_parent, head->ctl_table, head->root);
1227
1228 spin_lock(&sysctl_lock);
1229 err = -ENOMEM;
1230 if (!links)
1231 goto out;
1232
1233 err = 0;
1234 if (get_links(core_parent, head->ctl_table, head->root)) {
1235 kfree(links);
1236 goto out;
1237 }
1238
1239 err = insert_header(core_parent, links);
1240 if (err)
1241 kfree(links);
1242 out:
1243 drop_sysctl_table(&core_parent->header);
1244 return err;
1245 }
1246
1247 /**
1248 * __register_sysctl_table - register a leaf sysctl table
1249 * @set: Sysctl tree to register on
1250 * @path: The path to the directory the sysctl table is in.
1251 * @table: the top-level table structure
1252 *
1253 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1254 * array. A completely 0 filled entry terminates the table.
1255 *
1256 * The members of the &struct ctl_table structure are used as follows:
1257 *
1258 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1259 * enter a sysctl file
1260 *
1261 * data - a pointer to data for use by proc_handler
1262 *
1263 * maxlen - the maximum size in bytes of the data
1264 *
1265 * mode - the file permissions for the /proc/sys file
1266 *
1267 * child - must be %NULL.
1268 *
1269 * proc_handler - the text handler routine (described below)
1270 *
1271 * extra1, extra2 - extra pointers usable by the proc handler routines
1272 *
1273 * Leaf nodes in the sysctl tree will be represented by a single file
1274 * under /proc; non-leaf nodes will be represented by directories.
1275 *
1276 * There must be a proc_handler routine for any terminal nodes.
1277 * Several default handlers are available to cover common cases -
1278 *
1279 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1280 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1281 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1282 *
1283 * It is the handler's job to read the input buffer from user memory
1284 * and process it. The handler should return 0 on success.
1285 *
1286 * This routine returns %NULL on a failure to register, and a pointer
1287 * to the table header on success.
1288 */
1289 struct ctl_table_header *__register_sysctl_table(
1290 struct ctl_table_set *set,
1291 const char *path, struct ctl_table *table)
1292 {
1293 struct ctl_table_root *root = set->dir.header.root;
1294 struct ctl_table_header *header;
1295 const char *name, *nextname;
1296 struct ctl_dir *dir;
1297 struct ctl_table *entry;
1298 struct ctl_node *node;
1299 int nr_entries = 0;
1300
1301 for (entry = table; entry->procname; entry++)
1302 nr_entries++;
1303
1304 header = kzalloc(sizeof(struct ctl_table_header) +
1305 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1306 if (!header)
1307 return NULL;
1308
1309 node = (struct ctl_node *)(header + 1);
1310 init_header(header, root, set, node, table);
1311 if (sysctl_check_table(path, table))
1312 goto fail;
1313
1314 spin_lock(&sysctl_lock);
1315 dir = &set->dir;
1316 /* Reference moved down the diretory tree get_subdir */
1317 dir->header.nreg++;
1318 spin_unlock(&sysctl_lock);
1319
1320 /* Find the directory for the ctl_table */
1321 for (name = path; name; name = nextname) {
1322 int namelen;
1323 nextname = strchr(name, '/');
1324 if (nextname) {
1325 namelen = nextname - name;
1326 nextname++;
1327 } else {
1328 namelen = strlen(name);
1329 }
1330 if (namelen == 0)
1331 continue;
1332
1333 dir = get_subdir(dir, name, namelen);
1334 if (IS_ERR(dir))
1335 goto fail;
1336 }
1337
1338 spin_lock(&sysctl_lock);
1339 if (insert_header(dir, header))
1340 goto fail_put_dir_locked;
1341
1342 drop_sysctl_table(&dir->header);
1343 spin_unlock(&sysctl_lock);
1344
1345 return header;
1346
1347 fail_put_dir_locked:
1348 drop_sysctl_table(&dir->header);
1349 spin_unlock(&sysctl_lock);
1350 fail:
1351 kfree(header);
1352 dump_stack();
1353 return NULL;
1354 }
1355
1356 /**
1357 * register_sysctl - register a sysctl table
1358 * @path: The path to the directory the sysctl table is in.
1359 * @table: the table structure
1360 *
1361 * Register a sysctl table. @table should be a filled in ctl_table
1362 * array. A completely 0 filled entry terminates the table.
1363 *
1364 * See __register_sysctl_table for more details.
1365 */
1366 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1367 {
1368 return __register_sysctl_table(&sysctl_table_root.default_set,
1369 path, table);
1370 }
1371 EXPORT_SYMBOL(register_sysctl);
1372
1373 static char *append_path(const char *path, char *pos, const char *name)
1374 {
1375 int namelen;
1376 namelen = strlen(name);
1377 if (((pos - path) + namelen + 2) >= PATH_MAX)
1378 return NULL;
1379 memcpy(pos, name, namelen);
1380 pos[namelen] = '/';
1381 pos[namelen + 1] = '\0';
1382 pos += namelen + 1;
1383 return pos;
1384 }
1385
1386 static int count_subheaders(struct ctl_table *table)
1387 {
1388 int has_files = 0;
1389 int nr_subheaders = 0;
1390 struct ctl_table *entry;
1391
1392 /* special case: no directory and empty directory */
1393 if (!table || !table->procname)
1394 return 1;
1395
1396 for (entry = table; entry->procname; entry++) {
1397 if (entry->child)
1398 nr_subheaders += count_subheaders(entry->child);
1399 else
1400 has_files = 1;
1401 }
1402 return nr_subheaders + has_files;
1403 }
1404
1405 static int register_leaf_sysctl_tables(const char *path, char *pos,
1406 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1407 struct ctl_table *table)
1408 {
1409 struct ctl_table *ctl_table_arg = NULL;
1410 struct ctl_table *entry, *files;
1411 int nr_files = 0;
1412 int nr_dirs = 0;
1413 int err = -ENOMEM;
1414
1415 for (entry = table; entry->procname; entry++) {
1416 if (entry->child)
1417 nr_dirs++;
1418 else
1419 nr_files++;
1420 }
1421
1422 files = table;
1423 /* If there are mixed files and directories we need a new table */
1424 if (nr_dirs && nr_files) {
1425 struct ctl_table *new;
1426 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1427 GFP_KERNEL);
1428 if (!files)
1429 goto out;
1430
1431 ctl_table_arg = files;
1432 for (new = files, entry = table; entry->procname; entry++) {
1433 if (entry->child)
1434 continue;
1435 *new = *entry;
1436 new++;
1437 }
1438 }
1439
1440 /* Register everything except a directory full of subdirectories */
1441 if (nr_files || !nr_dirs) {
1442 struct ctl_table_header *header;
1443 header = __register_sysctl_table(set, path, files);
1444 if (!header) {
1445 kfree(ctl_table_arg);
1446 goto out;
1447 }
1448
1449 /* Remember if we need to free the file table */
1450 header->ctl_table_arg = ctl_table_arg;
1451 **subheader = header;
1452 (*subheader)++;
1453 }
1454
1455 /* Recurse into the subdirectories. */
1456 for (entry = table; entry->procname; entry++) {
1457 char *child_pos;
1458
1459 if (!entry->child)
1460 continue;
1461
1462 err = -ENAMETOOLONG;
1463 child_pos = append_path(path, pos, entry->procname);
1464 if (!child_pos)
1465 goto out;
1466
1467 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1468 set, entry->child);
1469 pos[0] = '\0';
1470 if (err)
1471 goto out;
1472 }
1473 err = 0;
1474 out:
1475 /* On failure our caller will unregister all registered subheaders */
1476 return err;
1477 }
1478
1479 /**
1480 * __register_sysctl_paths - register a sysctl table hierarchy
1481 * @set: Sysctl tree to register on
1482 * @path: The path to the directory the sysctl table is in.
1483 * @table: the top-level table structure
1484 *
1485 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1486 * array. A completely 0 filled entry terminates the table.
1487 *
1488 * See __register_sysctl_table for more details.
1489 */
1490 struct ctl_table_header *__register_sysctl_paths(
1491 struct ctl_table_set *set,
1492 const struct ctl_path *path, struct ctl_table *table)
1493 {
1494 struct ctl_table *ctl_table_arg = table;
1495 int nr_subheaders = count_subheaders(table);
1496 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1497 const struct ctl_path *component;
1498 char *new_path, *pos;
1499
1500 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1501 if (!new_path)
1502 return NULL;
1503
1504 pos[0] = '\0';
1505 for (component = path; component->procname; component++) {
1506 pos = append_path(new_path, pos, component->procname);
1507 if (!pos)
1508 goto out;
1509 }
1510 while (table->procname && table->child && !table[1].procname) {
1511 pos = append_path(new_path, pos, table->procname);
1512 if (!pos)
1513 goto out;
1514 table = table->child;
1515 }
1516 if (nr_subheaders == 1) {
1517 header = __register_sysctl_table(set, new_path, table);
1518 if (header)
1519 header->ctl_table_arg = ctl_table_arg;
1520 } else {
1521 header = kzalloc(sizeof(*header) +
1522 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1523 if (!header)
1524 goto out;
1525
1526 subheaders = (struct ctl_table_header **) (header + 1);
1527 subheader = subheaders;
1528 header->ctl_table_arg = ctl_table_arg;
1529
1530 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1531 set, table))
1532 goto err_register_leaves;
1533 }
1534
1535 out:
1536 kfree(new_path);
1537 return header;
1538
1539 err_register_leaves:
1540 while (subheader > subheaders) {
1541 struct ctl_table_header *subh = *(--subheader);
1542 struct ctl_table *table = subh->ctl_table_arg;
1543 unregister_sysctl_table(subh);
1544 kfree(table);
1545 }
1546 kfree(header);
1547 header = NULL;
1548 goto out;
1549 }
1550
1551 /**
1552 * register_sysctl_table_path - register a sysctl table hierarchy
1553 * @path: The path to the directory the sysctl table is in.
1554 * @table: the top-level table structure
1555 *
1556 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1557 * array. A completely 0 filled entry terminates the table.
1558 *
1559 * See __register_sysctl_paths for more details.
1560 */
1561 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1562 struct ctl_table *table)
1563 {
1564 return __register_sysctl_paths(&sysctl_table_root.default_set,
1565 path, table);
1566 }
1567 EXPORT_SYMBOL(register_sysctl_paths);
1568
1569 /**
1570 * register_sysctl_table - register a sysctl table hierarchy
1571 * @table: the top-level table structure
1572 *
1573 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1574 * array. A completely 0 filled entry terminates the table.
1575 *
1576 * See register_sysctl_paths for more details.
1577 */
1578 struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1579 {
1580 static const struct ctl_path null_path[] = { {} };
1581
1582 return register_sysctl_paths(null_path, table);
1583 }
1584 EXPORT_SYMBOL(register_sysctl_table);
1585
1586 static void put_links(struct ctl_table_header *header)
1587 {
1588 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1589 struct ctl_table_root *root = header->root;
1590 struct ctl_dir *parent = header->parent;
1591 struct ctl_dir *core_parent;
1592 struct ctl_table *entry;
1593
1594 if (header->set == root_set)
1595 return;
1596
1597 core_parent = xlate_dir(root_set, parent);
1598 if (IS_ERR(core_parent))
1599 return;
1600
1601 for (entry = header->ctl_table; entry->procname; entry++) {
1602 struct ctl_table_header *link_head;
1603 struct ctl_table *link;
1604 const char *name = entry->procname;
1605
1606 link = find_entry(&link_head, core_parent, name, strlen(name));
1607 if (link &&
1608 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1609 (S_ISLNK(link->mode) && (link->data == root)))) {
1610 drop_sysctl_table(link_head);
1611 }
1612 else {
1613 pr_err("sysctl link missing during unregister: ");
1614 sysctl_print_dir(parent);
1615 pr_cont("/%s\n", name);
1616 }
1617 }
1618 }
1619
1620 static void drop_sysctl_table(struct ctl_table_header *header)
1621 {
1622 struct ctl_dir *parent = header->parent;
1623
1624 if (--header->nreg)
1625 return;
1626
1627 if (parent) {
1628 put_links(header);
1629 start_unregistering(header);
1630 }
1631
1632 if (!--header->count)
1633 kfree_rcu(header, rcu);
1634
1635 if (parent)
1636 drop_sysctl_table(&parent->header);
1637 }
1638
1639 /**
1640 * unregister_sysctl_table - unregister a sysctl table hierarchy
1641 * @header: the header returned from register_sysctl_table
1642 *
1643 * Unregisters the sysctl table and all children. proc entries may not
1644 * actually be removed until they are no longer used by anyone.
1645 */
1646 void unregister_sysctl_table(struct ctl_table_header * header)
1647 {
1648 int nr_subheaders;
1649 might_sleep();
1650
1651 if (header == NULL)
1652 return;
1653
1654 nr_subheaders = count_subheaders(header->ctl_table_arg);
1655 if (unlikely(nr_subheaders > 1)) {
1656 struct ctl_table_header **subheaders;
1657 int i;
1658
1659 subheaders = (struct ctl_table_header **)(header + 1);
1660 for (i = nr_subheaders -1; i >= 0; i--) {
1661 struct ctl_table_header *subh = subheaders[i];
1662 struct ctl_table *table = subh->ctl_table_arg;
1663 unregister_sysctl_table(subh);
1664 kfree(table);
1665 }
1666 kfree(header);
1667 return;
1668 }
1669
1670 spin_lock(&sysctl_lock);
1671 drop_sysctl_table(header);
1672 spin_unlock(&sysctl_lock);
1673 }
1674 EXPORT_SYMBOL(unregister_sysctl_table);
1675
1676 void setup_sysctl_set(struct ctl_table_set *set,
1677 struct ctl_table_root *root,
1678 int (*is_seen)(struct ctl_table_set *))
1679 {
1680 memset(set, 0, sizeof(*set));
1681 set->is_seen = is_seen;
1682 init_header(&set->dir.header, root, set, NULL, root_table);
1683 }
1684
1685 void retire_sysctl_set(struct ctl_table_set *set)
1686 {
1687 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1688 }
1689
1690 int __init proc_sys_init(void)
1691 {
1692 struct proc_dir_entry *proc_sys_root;
1693
1694 proc_sys_root = proc_mkdir("sys", NULL);
1695 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1696 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1697 proc_sys_root->nlink = 0;
1698
1699 return sysctl_init();
1700 }
Linux with added FPC-III support