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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/uio.h>
16#include <linux/module.h>
17#include <linux/bpf-cgroup.h>
18#include <linux/mount.h>
19#include "internal.h"
20
21static const struct dentry_operations proc_sys_dentry_operations;
22static const struct file_operations proc_sys_file_operations;
23static const struct inode_operations proc_sys_inode_operations;
24static const struct file_operations proc_sys_dir_file_operations;
25static const struct inode_operations proc_sys_dir_operations;
26
27/* shared constants to be used in various sysctls */
28const int sysctl_vals[] = { 0, 1, INT_MAX };
29EXPORT_SYMBOL(sysctl_vals);
30
31/* Support for permanently empty directories */
32
33struct ctl_table sysctl_mount_point[] = {
34 { }
35};
36
37static bool is_empty_dir(struct ctl_table_header *head)
38{
39 return head->ctl_table[0].child == sysctl_mount_point;
40}
41
42static void set_empty_dir(struct ctl_dir *dir)
43{
44 dir->header.ctl_table[0].child = sysctl_mount_point;
45}
46
47static void clear_empty_dir(struct ctl_dir *dir)
48
49{
50 dir->header.ctl_table[0].child = NULL;
51}
52
53void proc_sys_poll_notify(struct ctl_table_poll *poll)
54{
55 if (!poll)
56 return;
57
58 atomic_inc(&poll->event);
59 wake_up_interruptible(&poll->wait);
60}
61
62static struct ctl_table root_table[] = {
63 {
64 .procname = "",
65 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
66 },
67 { }
68};
69static struct ctl_table_root sysctl_table_root = {
70 .default_set.dir.header = {
71 {{.count = 1,
72 .nreg = 1,
73 .ctl_table = root_table }},
74 .ctl_table_arg = root_table,
75 .root = &sysctl_table_root,
76 .set = &sysctl_table_root.default_set,
77 },
78};
79
80static DEFINE_SPINLOCK(sysctl_lock);
81
82static void drop_sysctl_table(struct ctl_table_header *header);
83static int sysctl_follow_link(struct ctl_table_header **phead,
84 struct ctl_table **pentry);
85static int insert_links(struct ctl_table_header *head);
86static void put_links(struct ctl_table_header *header);
87
88static void sysctl_print_dir(struct ctl_dir *dir)
89{
90 if (dir->header.parent)
91 sysctl_print_dir(dir->header.parent);
92 pr_cont("%s/", dir->header.ctl_table[0].procname);
93}
94
95static int namecmp(const char *name1, int len1, const char *name2, int len2)
96{
97 int cmp;
98
99 cmp = memcmp(name1, name2, min(len1, len2));
100 if (cmp == 0)
101 cmp = len1 - len2;
102 return cmp;
103}
104
105/* Called under sysctl_lock */
106static struct ctl_table *find_entry(struct ctl_table_header **phead,
107 struct ctl_dir *dir, const char *name, int namelen)
108{
109 struct ctl_table_header *head;
110 struct ctl_table *entry;
111 struct rb_node *node = dir->root.rb_node;
112
113 while (node)
114 {
115 struct ctl_node *ctl_node;
116 const char *procname;
117 int cmp;
118
119 ctl_node = rb_entry(node, struct ctl_node, node);
120 head = ctl_node->header;
121 entry = &head->ctl_table[ctl_node - head->node];
122 procname = entry->procname;
123
124 cmp = namecmp(name, namelen, procname, strlen(procname));
125 if (cmp < 0)
126 node = node->rb_left;
127 else if (cmp > 0)
128 node = node->rb_right;
129 else {
130 *phead = head;
131 return entry;
132 }
133 }
134 return NULL;
135}
136
137static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
138{
139 struct rb_node *node = &head->node[entry - head->ctl_table].node;
140 struct rb_node **p = &head->parent->root.rb_node;
141 struct rb_node *parent = NULL;
142 const char *name = entry->procname;
143 int namelen = strlen(name);
144
145 while (*p) {
146 struct ctl_table_header *parent_head;
147 struct ctl_table *parent_entry;
148 struct ctl_node *parent_node;
149 const char *parent_name;
150 int cmp;
151
152 parent = *p;
153 parent_node = rb_entry(parent, struct ctl_node, node);
154 parent_head = parent_node->header;
155 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
156 parent_name = parent_entry->procname;
157
158 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
159 if (cmp < 0)
160 p = &(*p)->rb_left;
161 else if (cmp > 0)
162 p = &(*p)->rb_right;
163 else {
164 pr_err("sysctl duplicate entry: ");
165 sysctl_print_dir(head->parent);
166 pr_cont("/%s\n", entry->procname);
167 return -EEXIST;
168 }
169 }
170
171 rb_link_node(node, parent, p);
172 rb_insert_color(node, &head->parent->root);
173 return 0;
174}
175
176static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
177{
178 struct rb_node *node = &head->node[entry - head->ctl_table].node;
179
180 rb_erase(node, &head->parent->root);
181}
182
183static void init_header(struct ctl_table_header *head,
184 struct ctl_table_root *root, struct ctl_table_set *set,
185 struct ctl_node *node, struct ctl_table *table)
186{
187 head->ctl_table = table;
188 head->ctl_table_arg = table;
189 head->used = 0;
190 head->count = 1;
191 head->nreg = 1;
192 head->unregistering = NULL;
193 head->root = root;
194 head->set = set;
195 head->parent = NULL;
196 head->node = node;
197 INIT_HLIST_HEAD(&head->inodes);
198 if (node) {
199 struct ctl_table *entry;
200 for (entry = table; entry->procname; entry++, node++)
201 node->header = head;
202 }
203}
204
205static void erase_header(struct ctl_table_header *head)
206{
207 struct ctl_table *entry;
208 for (entry = head->ctl_table; entry->procname; entry++)
209 erase_entry(head, entry);
210}
211
212static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
213{
214 struct ctl_table *entry;
215 int err;
216
217 /* Is this a permanently empty directory? */
218 if (is_empty_dir(&dir->header))
219 return -EROFS;
220
221 /* Am I creating a permanently empty directory? */
222 if (header->ctl_table == sysctl_mount_point) {
223 if (!RB_EMPTY_ROOT(&dir->root))
224 return -EINVAL;
225 set_empty_dir(dir);
226 }
227
228 dir->header.nreg++;
229 header->parent = dir;
230 err = insert_links(header);
231 if (err)
232 goto fail_links;
233 for (entry = header->ctl_table; entry->procname; entry++) {
234 err = insert_entry(header, entry);
235 if (err)
236 goto fail;
237 }
238 return 0;
239fail:
240 erase_header(header);
241 put_links(header);
242fail_links:
243 if (header->ctl_table == sysctl_mount_point)
244 clear_empty_dir(dir);
245 header->parent = NULL;
246 drop_sysctl_table(&dir->header);
247 return err;
248}
249
250/* called under sysctl_lock */
251static int use_table(struct ctl_table_header *p)
252{
253 if (unlikely(p->unregistering))
254 return 0;
255 p->used++;
256 return 1;
257}
258
259/* called under sysctl_lock */
260static void unuse_table(struct ctl_table_header *p)
261{
262 if (!--p->used)
263 if (unlikely(p->unregistering))
264 complete(p->unregistering);
265}
266
267static void proc_sys_invalidate_dcache(struct ctl_table_header *head)
268{
269 proc_invalidate_siblings_dcache(&head->inodes, &sysctl_lock);
270}
271
272/* called under sysctl_lock, will reacquire if has to wait */
273static void start_unregistering(struct ctl_table_header *p)
274{
275 /*
276 * if p->used is 0, nobody will ever touch that entry again;
277 * we'll eliminate all paths to it before dropping sysctl_lock
278 */
279 if (unlikely(p->used)) {
280 struct completion wait;
281 init_completion(&wait);
282 p->unregistering = &wait;
283 spin_unlock(&sysctl_lock);
284 wait_for_completion(&wait);
285 } else {
286 /* anything non-NULL; we'll never dereference it */
287 p->unregistering = ERR_PTR(-EINVAL);
288 spin_unlock(&sysctl_lock);
289 }
290 /*
291 * Invalidate dentries for unregistered sysctls: namespaced sysctls
292 * can have duplicate names and contaminate dcache very badly.
293 */
294 proc_sys_invalidate_dcache(p);
295 /*
296 * do not remove from the list until nobody holds it; walking the
297 * list in do_sysctl() relies on that.
298 */
299 spin_lock(&sysctl_lock);
300 erase_header(p);
301}
302
303static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
304{
305 BUG_ON(!head);
306 spin_lock(&sysctl_lock);
307 if (!use_table(head))
308 head = ERR_PTR(-ENOENT);
309 spin_unlock(&sysctl_lock);
310 return head;
311}
312
313static void sysctl_head_finish(struct ctl_table_header *head)
314{
315 if (!head)
316 return;
317 spin_lock(&sysctl_lock);
318 unuse_table(head);
319 spin_unlock(&sysctl_lock);
320}
321
322static struct ctl_table_set *
323lookup_header_set(struct ctl_table_root *root)
324{
325 struct ctl_table_set *set = &root->default_set;
326 if (root->lookup)
327 set = root->lookup(root);
328 return set;
329}
330
331static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
332 struct ctl_dir *dir,
333 const char *name, int namelen)
334{
335 struct ctl_table_header *head;
336 struct ctl_table *entry;
337
338 spin_lock(&sysctl_lock);
339 entry = find_entry(&head, dir, name, namelen);
340 if (entry && use_table(head))
341 *phead = head;
342 else
343 entry = NULL;
344 spin_unlock(&sysctl_lock);
345 return entry;
346}
347
348static struct ctl_node *first_usable_entry(struct rb_node *node)
349{
350 struct ctl_node *ctl_node;
351
352 for (;node; node = rb_next(node)) {
353 ctl_node = rb_entry(node, struct ctl_node, node);
354 if (use_table(ctl_node->header))
355 return ctl_node;
356 }
357 return NULL;
358}
359
360static void first_entry(struct ctl_dir *dir,
361 struct ctl_table_header **phead, struct ctl_table **pentry)
362{
363 struct ctl_table_header *head = NULL;
364 struct ctl_table *entry = NULL;
365 struct ctl_node *ctl_node;
366
367 spin_lock(&sysctl_lock);
368 ctl_node = first_usable_entry(rb_first(&dir->root));
369 spin_unlock(&sysctl_lock);
370 if (ctl_node) {
371 head = ctl_node->header;
372 entry = &head->ctl_table[ctl_node - head->node];
373 }
374 *phead = head;
375 *pentry = entry;
376}
377
378static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
379{
380 struct ctl_table_header *head = *phead;
381 struct ctl_table *entry = *pentry;
382 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
383
384 spin_lock(&sysctl_lock);
385 unuse_table(head);
386
387 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
388 spin_unlock(&sysctl_lock);
389 head = NULL;
390 if (ctl_node) {
391 head = ctl_node->header;
392 entry = &head->ctl_table[ctl_node - head->node];
393 }
394 *phead = head;
395 *pentry = entry;
396}
397
398/*
399 * sysctl_perm does NOT grant the superuser all rights automatically, because
400 * some sysctl variables are readonly even to root.
401 */
402
403static int test_perm(int mode, int op)
404{
405 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
406 mode >>= 6;
407 else if (in_egroup_p(GLOBAL_ROOT_GID))
408 mode >>= 3;
409 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
410 return 0;
411 return -EACCES;
412}
413
414static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
415{
416 struct ctl_table_root *root = head->root;
417 int mode;
418
419 if (root->permissions)
420 mode = root->permissions(head, table);
421 else
422 mode = table->mode;
423
424 return test_perm(mode, op);
425}
426
427static struct inode *proc_sys_make_inode(struct super_block *sb,
428 struct ctl_table_header *head, struct ctl_table *table)
429{
430 struct ctl_table_root *root = head->root;
431 struct inode *inode;
432 struct proc_inode *ei;
433
434 inode = new_inode(sb);
435 if (!inode)
436 return ERR_PTR(-ENOMEM);
437
438 inode->i_ino = get_next_ino();
439
440 ei = PROC_I(inode);
441
442 spin_lock(&sysctl_lock);
443 if (unlikely(head->unregistering)) {
444 spin_unlock(&sysctl_lock);
445 iput(inode);
446 return ERR_PTR(-ENOENT);
447 }
448 ei->sysctl = head;
449 ei->sysctl_entry = table;
450 hlist_add_head_rcu(&ei->sibling_inodes, &head->inodes);
451 head->count++;
452 spin_unlock(&sysctl_lock);
453
454 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
455 inode->i_mode = table->mode;
456 if (!S_ISDIR(table->mode)) {
457 inode->i_mode |= S_IFREG;
458 inode->i_op = &proc_sys_inode_operations;
459 inode->i_fop = &proc_sys_file_operations;
460 } else {
461 inode->i_mode |= S_IFDIR;
462 inode->i_op = &proc_sys_dir_operations;
463 inode->i_fop = &proc_sys_dir_file_operations;
464 if (is_empty_dir(head))
465 make_empty_dir_inode(inode);
466 }
467
468 if (root->set_ownership)
469 root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
470 else {
471 inode->i_uid = GLOBAL_ROOT_UID;
472 inode->i_gid = GLOBAL_ROOT_GID;
473 }
474
475 return inode;
476}
477
478void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
479{
480 spin_lock(&sysctl_lock);
481 hlist_del_init_rcu(&PROC_I(inode)->sibling_inodes);
482 if (!--head->count)
483 kfree_rcu(head, rcu);
484 spin_unlock(&sysctl_lock);
485}
486
487static struct ctl_table_header *grab_header(struct inode *inode)
488{
489 struct ctl_table_header *head = PROC_I(inode)->sysctl;
490 if (!head)
491 head = &sysctl_table_root.default_set.dir.header;
492 return sysctl_head_grab(head);
493}
494
495static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
496 unsigned int flags)
497{
498 struct ctl_table_header *head = grab_header(dir);
499 struct ctl_table_header *h = NULL;
500 const struct qstr *name = &dentry->d_name;
501 struct ctl_table *p;
502 struct inode *inode;
503 struct dentry *err = ERR_PTR(-ENOENT);
504 struct ctl_dir *ctl_dir;
505 int ret;
506
507 if (IS_ERR(head))
508 return ERR_CAST(head);
509
510 ctl_dir = container_of(head, struct ctl_dir, header);
511
512 p = lookup_entry(&h, ctl_dir, name->name, name->len);
513 if (!p)
514 goto out;
515
516 if (S_ISLNK(p->mode)) {
517 ret = sysctl_follow_link(&h, &p);
518 err = ERR_PTR(ret);
519 if (ret)
520 goto out;
521 }
522
523 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
524 if (IS_ERR(inode)) {
525 err = ERR_CAST(inode);
526 goto out;
527 }
528
529 d_set_d_op(dentry, &proc_sys_dentry_operations);
530 err = d_splice_alias(inode, dentry);
531
532out:
533 if (h)
534 sysctl_head_finish(h);
535 sysctl_head_finish(head);
536 return err;
537}
538
539static ssize_t proc_sys_call_handler(struct kiocb *iocb, struct iov_iter *iter,
540 int write)
541{
542 struct inode *inode = file_inode(iocb->ki_filp);
543 struct ctl_table_header *head = grab_header(inode);
544 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
545 size_t count = iov_iter_count(iter);
546 char *kbuf;
547 ssize_t error;
548
549 if (IS_ERR(head))
550 return PTR_ERR(head);
551
552 /*
553 * At this point we know that the sysctl was not unregistered
554 * and won't be until we finish.
555 */
556 error = -EPERM;
557 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
558 goto out;
559
560 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
561 error = -EINVAL;
562 if (!table->proc_handler)
563 goto out;
564
565 /* don't even try if the size is too large */
566 error = -ENOMEM;
567 if (count >= KMALLOC_MAX_SIZE)
568 goto out;
569 kbuf = kvzalloc(count + 1, GFP_KERNEL);
570 if (!kbuf)
571 goto out;
572
573 if (write) {
574 error = -EFAULT;
575 if (!copy_from_iter_full(kbuf, count, iter))
576 goto out_free_buf;
577 kbuf[count] = '\0';
578 }
579
580 error = BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, &kbuf, &count,
581 &iocb->ki_pos);
582 if (error)
583 goto out_free_buf;
584
585 /* careful: calling conventions are nasty here */
586 error = table->proc_handler(table, write, kbuf, &count, &iocb->ki_pos);
587 if (error)
588 goto out_free_buf;
589
590 if (!write) {
591 error = -EFAULT;
592 if (copy_to_iter(kbuf, count, iter) < count)
593 goto out_free_buf;
594 }
595
596 error = count;
597out_free_buf:
598 kvfree(kbuf);
599out:
600 sysctl_head_finish(head);
601
602 return error;
603}
604
605static ssize_t proc_sys_read(struct kiocb *iocb, struct iov_iter *iter)
606{
607 return proc_sys_call_handler(iocb, iter, 0);
608}
609
610static ssize_t proc_sys_write(struct kiocb *iocb, struct iov_iter *iter)
611{
612 return proc_sys_call_handler(iocb, iter, 1);
613}
614
615static int proc_sys_open(struct inode *inode, struct file *filp)
616{
617 struct ctl_table_header *head = grab_header(inode);
618 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
619
620 /* sysctl was unregistered */
621 if (IS_ERR(head))
622 return PTR_ERR(head);
623
624 if (table->poll)
625 filp->private_data = proc_sys_poll_event(table->poll);
626
627 sysctl_head_finish(head);
628
629 return 0;
630}
631
632static __poll_t proc_sys_poll(struct file *filp, poll_table *wait)
633{
634 struct inode *inode = file_inode(filp);
635 struct ctl_table_header *head = grab_header(inode);
636 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
637 __poll_t ret = DEFAULT_POLLMASK;
638 unsigned long event;
639
640 /* sysctl was unregistered */
641 if (IS_ERR(head))
642 return EPOLLERR | EPOLLHUP;
643
644 if (!table->proc_handler)
645 goto out;
646
647 if (!table->poll)
648 goto out;
649
650 event = (unsigned long)filp->private_data;
651 poll_wait(filp, &table->poll->wait, wait);
652
653 if (event != atomic_read(&table->poll->event)) {
654 filp->private_data = proc_sys_poll_event(table->poll);
655 ret = EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI;
656 }
657
658out:
659 sysctl_head_finish(head);
660
661 return ret;
662}
663
664static bool proc_sys_fill_cache(struct file *file,
665 struct dir_context *ctx,
666 struct ctl_table_header *head,
667 struct ctl_table *table)
668{
669 struct dentry *child, *dir = file->f_path.dentry;
670 struct inode *inode;
671 struct qstr qname;
672 ino_t ino = 0;
673 unsigned type = DT_UNKNOWN;
674
675 qname.name = table->procname;
676 qname.len = strlen(table->procname);
677 qname.hash = full_name_hash(dir, qname.name, qname.len);
678
679 child = d_lookup(dir, &qname);
680 if (!child) {
681 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
682 child = d_alloc_parallel(dir, &qname, &wq);
683 if (IS_ERR(child))
684 return false;
685 if (d_in_lookup(child)) {
686 struct dentry *res;
687 inode = proc_sys_make_inode(dir->d_sb, head, table);
688 if (IS_ERR(inode)) {
689 d_lookup_done(child);
690 dput(child);
691 return false;
692 }
693 d_set_d_op(child, &proc_sys_dentry_operations);
694 res = d_splice_alias(inode, child);
695 d_lookup_done(child);
696 if (unlikely(res)) {
697 if (IS_ERR(res)) {
698 dput(child);
699 return false;
700 }
701 dput(child);
702 child = res;
703 }
704 }
705 }
706 inode = d_inode(child);
707 ino = inode->i_ino;
708 type = inode->i_mode >> 12;
709 dput(child);
710 return dir_emit(ctx, qname.name, qname.len, ino, type);
711}
712
713static bool proc_sys_link_fill_cache(struct file *file,
714 struct dir_context *ctx,
715 struct ctl_table_header *head,
716 struct ctl_table *table)
717{
718 bool ret = true;
719
720 head = sysctl_head_grab(head);
721 if (IS_ERR(head))
722 return false;
723
724 /* It is not an error if we can not follow the link ignore it */
725 if (sysctl_follow_link(&head, &table))
726 goto out;
727
728 ret = proc_sys_fill_cache(file, ctx, head, table);
729out:
730 sysctl_head_finish(head);
731 return ret;
732}
733
734static int scan(struct ctl_table_header *head, struct ctl_table *table,
735 unsigned long *pos, struct file *file,
736 struct dir_context *ctx)
737{
738 bool res;
739
740 if ((*pos)++ < ctx->pos)
741 return true;
742
743 if (unlikely(S_ISLNK(table->mode)))
744 res = proc_sys_link_fill_cache(file, ctx, head, table);
745 else
746 res = proc_sys_fill_cache(file, ctx, head, table);
747
748 if (res)
749 ctx->pos = *pos;
750
751 return res;
752}
753
754static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
755{
756 struct ctl_table_header *head = grab_header(file_inode(file));
757 struct ctl_table_header *h = NULL;
758 struct ctl_table *entry;
759 struct ctl_dir *ctl_dir;
760 unsigned long pos;
761
762 if (IS_ERR(head))
763 return PTR_ERR(head);
764
765 ctl_dir = container_of(head, struct ctl_dir, header);
766
767 if (!dir_emit_dots(file, ctx))
768 goto out;
769
770 pos = 2;
771
772 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
773 if (!scan(h, entry, &pos, file, ctx)) {
774 sysctl_head_finish(h);
775 break;
776 }
777 }
778out:
779 sysctl_head_finish(head);
780 return 0;
781}
782
783static int proc_sys_permission(struct user_namespace *mnt_userns,
784 struct inode *inode, int mask)
785{
786 /*
787 * sysctl entries that are not writeable,
788 * are _NOT_ writeable, capabilities or not.
789 */
790 struct ctl_table_header *head;
791 struct ctl_table *table;
792 int error;
793
794 /* Executable files are not allowed under /proc/sys/ */
795 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
796 return -EACCES;
797
798 head = grab_header(inode);
799 if (IS_ERR(head))
800 return PTR_ERR(head);
801
802 table = PROC_I(inode)->sysctl_entry;
803 if (!table) /* global root - r-xr-xr-x */
804 error = mask & MAY_WRITE ? -EACCES : 0;
805 else /* Use the permissions on the sysctl table entry */
806 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
807
808 sysctl_head_finish(head);
809 return error;
810}
811
812static int proc_sys_setattr(struct user_namespace *mnt_userns,
813 struct dentry *dentry, struct iattr *attr)
814{
815 struct inode *inode = d_inode(dentry);
816 int error;
817
818 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
819 return -EPERM;
820
821 error = setattr_prepare(&init_user_ns, dentry, attr);
822 if (error)
823 return error;
824
825 setattr_copy(&init_user_ns, inode, attr);
826 mark_inode_dirty(inode);
827 return 0;
828}
829
830static int proc_sys_getattr(struct user_namespace *mnt_userns,
831 const struct path *path, struct kstat *stat,
832 u32 request_mask, unsigned int query_flags)
833{
834 struct inode *inode = d_inode(path->dentry);
835 struct ctl_table_header *head = grab_header(inode);
836 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
837
838 if (IS_ERR(head))
839 return PTR_ERR(head);
840
841 generic_fillattr(&init_user_ns, inode, stat);
842 if (table)
843 stat->mode = (stat->mode & S_IFMT) | table->mode;
844
845 sysctl_head_finish(head);
846 return 0;
847}
848
849static const struct file_operations proc_sys_file_operations = {
850 .open = proc_sys_open,
851 .poll = proc_sys_poll,
852 .read_iter = proc_sys_read,
853 .write_iter = proc_sys_write,
854 .splice_read = generic_file_splice_read,
855 .splice_write = iter_file_splice_write,
856 .llseek = default_llseek,
857};
858
859static const struct file_operations proc_sys_dir_file_operations = {
860 .read = generic_read_dir,
861 .iterate_shared = proc_sys_readdir,
862 .llseek = generic_file_llseek,
863};
864
865static const struct inode_operations proc_sys_inode_operations = {
866 .permission = proc_sys_permission,
867 .setattr = proc_sys_setattr,
868 .getattr = proc_sys_getattr,
869};
870
871static const struct inode_operations proc_sys_dir_operations = {
872 .lookup = proc_sys_lookup,
873 .permission = proc_sys_permission,
874 .setattr = proc_sys_setattr,
875 .getattr = proc_sys_getattr,
876};
877
878static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
879{
880 if (flags & LOOKUP_RCU)
881 return -ECHILD;
882 return !PROC_I(d_inode(dentry))->sysctl->unregistering;
883}
884
885static int proc_sys_delete(const struct dentry *dentry)
886{
887 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
888}
889
890static int sysctl_is_seen(struct ctl_table_header *p)
891{
892 struct ctl_table_set *set = p->set;
893 int res;
894 spin_lock(&sysctl_lock);
895 if (p->unregistering)
896 res = 0;
897 else if (!set->is_seen)
898 res = 1;
899 else
900 res = set->is_seen(set);
901 spin_unlock(&sysctl_lock);
902 return res;
903}
904
905static int proc_sys_compare(const struct dentry *dentry,
906 unsigned int len, const char *str, const struct qstr *name)
907{
908 struct ctl_table_header *head;
909 struct inode *inode;
910
911 /* Although proc doesn't have negative dentries, rcu-walk means
912 * that inode here can be NULL */
913 /* AV: can it, indeed? */
914 inode = d_inode_rcu(dentry);
915 if (!inode)
916 return 1;
917 if (name->len != len)
918 return 1;
919 if (memcmp(name->name, str, len))
920 return 1;
921 head = rcu_dereference(PROC_I(inode)->sysctl);
922 return !head || !sysctl_is_seen(head);
923}
924
925static const struct dentry_operations proc_sys_dentry_operations = {
926 .d_revalidate = proc_sys_revalidate,
927 .d_delete = proc_sys_delete,
928 .d_compare = proc_sys_compare,
929};
930
931static struct ctl_dir *find_subdir(struct ctl_dir *dir,
932 const char *name, int namelen)
933{
934 struct ctl_table_header *head;
935 struct ctl_table *entry;
936
937 entry = find_entry(&head, dir, name, namelen);
938 if (!entry)
939 return ERR_PTR(-ENOENT);
940 if (!S_ISDIR(entry->mode))
941 return ERR_PTR(-ENOTDIR);
942 return container_of(head, struct ctl_dir, header);
943}
944
945static struct ctl_dir *new_dir(struct ctl_table_set *set,
946 const char *name, int namelen)
947{
948 struct ctl_table *table;
949 struct ctl_dir *new;
950 struct ctl_node *node;
951 char *new_name;
952
953 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
954 sizeof(struct ctl_table)*2 + namelen + 1,
955 GFP_KERNEL);
956 if (!new)
957 return NULL;
958
959 node = (struct ctl_node *)(new + 1);
960 table = (struct ctl_table *)(node + 1);
961 new_name = (char *)(table + 2);
962 memcpy(new_name, name, namelen);
963 new_name[namelen] = '\0';
964 table[0].procname = new_name;
965 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
966 init_header(&new->header, set->dir.header.root, set, node, table);
967
968 return new;
969}
970
971/**
972 * get_subdir - find or create a subdir with the specified name.
973 * @dir: Directory to create the subdirectory in
974 * @name: The name of the subdirectory to find or create
975 * @namelen: The length of name
976 *
977 * Takes a directory with an elevated reference count so we know that
978 * if we drop the lock the directory will not go away. Upon success
979 * the reference is moved from @dir to the returned subdirectory.
980 * Upon error an error code is returned and the reference on @dir is
981 * simply dropped.
982 */
983static struct ctl_dir *get_subdir(struct ctl_dir *dir,
984 const char *name, int namelen)
985{
986 struct ctl_table_set *set = dir->header.set;
987 struct ctl_dir *subdir, *new = NULL;
988 int err;
989
990 spin_lock(&sysctl_lock);
991 subdir = find_subdir(dir, name, namelen);
992 if (!IS_ERR(subdir))
993 goto found;
994 if (PTR_ERR(subdir) != -ENOENT)
995 goto failed;
996
997 spin_unlock(&sysctl_lock);
998 new = new_dir(set, name, namelen);
999 spin_lock(&sysctl_lock);
1000 subdir = ERR_PTR(-ENOMEM);
1001 if (!new)
1002 goto failed;
1003
1004 /* Was the subdir added while we dropped the lock? */
1005 subdir = find_subdir(dir, name, namelen);
1006 if (!IS_ERR(subdir))
1007 goto found;
1008 if (PTR_ERR(subdir) != -ENOENT)
1009 goto failed;
1010
1011 /* Nope. Use the our freshly made directory entry. */
1012 err = insert_header(dir, &new->header);
1013 subdir = ERR_PTR(err);
1014 if (err)
1015 goto failed;
1016 subdir = new;
1017found:
1018 subdir->header.nreg++;
1019failed:
1020 if (IS_ERR(subdir)) {
1021 pr_err("sysctl could not get directory: ");
1022 sysctl_print_dir(dir);
1023 pr_cont("/%*.*s %ld\n",
1024 namelen, namelen, name, PTR_ERR(subdir));
1025 }
1026 drop_sysctl_table(&dir->header);
1027 if (new)
1028 drop_sysctl_table(&new->header);
1029 spin_unlock(&sysctl_lock);
1030 return subdir;
1031}
1032
1033static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
1034{
1035 struct ctl_dir *parent;
1036 const char *procname;
1037 if (!dir->header.parent)
1038 return &set->dir;
1039 parent = xlate_dir(set, dir->header.parent);
1040 if (IS_ERR(parent))
1041 return parent;
1042 procname = dir->header.ctl_table[0].procname;
1043 return find_subdir(parent, procname, strlen(procname));
1044}
1045
1046static int sysctl_follow_link(struct ctl_table_header **phead,
1047 struct ctl_table **pentry)
1048{
1049 struct ctl_table_header *head;
1050 struct ctl_table_root *root;
1051 struct ctl_table_set *set;
1052 struct ctl_table *entry;
1053 struct ctl_dir *dir;
1054 int ret;
1055
1056 ret = 0;
1057 spin_lock(&sysctl_lock);
1058 root = (*pentry)->data;
1059 set = lookup_header_set(root);
1060 dir = xlate_dir(set, (*phead)->parent);
1061 if (IS_ERR(dir))
1062 ret = PTR_ERR(dir);
1063 else {
1064 const char *procname = (*pentry)->procname;
1065 head = NULL;
1066 entry = find_entry(&head, dir, procname, strlen(procname));
1067 ret = -ENOENT;
1068 if (entry && use_table(head)) {
1069 unuse_table(*phead);
1070 *phead = head;
1071 *pentry = entry;
1072 ret = 0;
1073 }
1074 }
1075
1076 spin_unlock(&sysctl_lock);
1077 return ret;
1078}
1079
1080static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
1081{
1082 struct va_format vaf;
1083 va_list args;
1084
1085 va_start(args, fmt);
1086 vaf.fmt = fmt;
1087 vaf.va = &args;
1088
1089 pr_err("sysctl table check failed: %s/%s %pV\n",
1090 path, table->procname, &vaf);
1091
1092 va_end(args);
1093 return -EINVAL;
1094}
1095
1096static int sysctl_check_table_array(const char *path, struct ctl_table *table)
1097{
1098 int err = 0;
1099
1100 if ((table->proc_handler == proc_douintvec) ||
1101 (table->proc_handler == proc_douintvec_minmax)) {
1102 if (table->maxlen != sizeof(unsigned int))
1103 err |= sysctl_err(path, table, "array not allowed");
1104 }
1105
1106 if (table->proc_handler == proc_dou8vec_minmax) {
1107 if (table->maxlen != sizeof(u8))
1108 err |= sysctl_err(path, table, "array not allowed");
1109 }
1110
1111 return err;
1112}
1113
1114static int sysctl_check_table(const char *path, struct ctl_table *table)
1115{
1116 int err = 0;
1117 for (; table->procname; table++) {
1118 if (table->child)
1119 err |= sysctl_err(path, table, "Not a file");
1120
1121 if ((table->proc_handler == proc_dostring) ||
1122 (table->proc_handler == proc_dointvec) ||
1123 (table->proc_handler == proc_douintvec) ||
1124 (table->proc_handler == proc_douintvec_minmax) ||
1125 (table->proc_handler == proc_dointvec_minmax) ||
1126 (table->proc_handler == proc_dou8vec_minmax) ||
1127 (table->proc_handler == proc_dointvec_jiffies) ||
1128 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1129 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1130 (table->proc_handler == proc_doulongvec_minmax) ||
1131 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1132 if (!table->data)
1133 err |= sysctl_err(path, table, "No data");
1134 if (!table->maxlen)
1135 err |= sysctl_err(path, table, "No maxlen");
1136 else
1137 err |= sysctl_check_table_array(path, table);
1138 }
1139 if (!table->proc_handler)
1140 err |= sysctl_err(path, table, "No proc_handler");
1141
1142 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1143 err |= sysctl_err(path, table, "bogus .mode 0%o",
1144 table->mode);
1145 }
1146 return err;
1147}
1148
1149static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1150 struct ctl_table_root *link_root)
1151{
1152 struct ctl_table *link_table, *entry, *link;
1153 struct ctl_table_header *links;
1154 struct ctl_node *node;
1155 char *link_name;
1156 int nr_entries, name_bytes;
1157
1158 name_bytes = 0;
1159 nr_entries = 0;
1160 for (entry = table; entry->procname; entry++) {
1161 nr_entries++;
1162 name_bytes += strlen(entry->procname) + 1;
1163 }
1164
1165 links = kzalloc(sizeof(struct ctl_table_header) +
1166 sizeof(struct ctl_node)*nr_entries +
1167 sizeof(struct ctl_table)*(nr_entries + 1) +
1168 name_bytes,
1169 GFP_KERNEL);
1170
1171 if (!links)
1172 return NULL;
1173
1174 node = (struct ctl_node *)(links + 1);
1175 link_table = (struct ctl_table *)(node + nr_entries);
1176 link_name = (char *)&link_table[nr_entries + 1];
1177
1178 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1179 int len = strlen(entry->procname) + 1;
1180 memcpy(link_name, entry->procname, len);
1181 link->procname = link_name;
1182 link->mode = S_IFLNK|S_IRWXUGO;
1183 link->data = link_root;
1184 link_name += len;
1185 }
1186 init_header(links, dir->header.root, dir->header.set, node, link_table);
1187 links->nreg = nr_entries;
1188
1189 return links;
1190}
1191
1192static bool get_links(struct ctl_dir *dir,
1193 struct ctl_table *table, struct ctl_table_root *link_root)
1194{
1195 struct ctl_table_header *head;
1196 struct ctl_table *entry, *link;
1197
1198 /* Are there links available for every entry in table? */
1199 for (entry = table; entry->procname; entry++) {
1200 const char *procname = entry->procname;
1201 link = find_entry(&head, dir, procname, strlen(procname));
1202 if (!link)
1203 return false;
1204 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1205 continue;
1206 if (S_ISLNK(link->mode) && (link->data == link_root))
1207 continue;
1208 return false;
1209 }
1210
1211 /* The checks passed. Increase the registration count on the links */
1212 for (entry = table; entry->procname; entry++) {
1213 const char *procname = entry->procname;
1214 link = find_entry(&head, dir, procname, strlen(procname));
1215 head->nreg++;
1216 }
1217 return true;
1218}
1219
1220static int insert_links(struct ctl_table_header *head)
1221{
1222 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1223 struct ctl_dir *core_parent = NULL;
1224 struct ctl_table_header *links;
1225 int err;
1226
1227 if (head->set == root_set)
1228 return 0;
1229
1230 core_parent = xlate_dir(root_set, head->parent);
1231 if (IS_ERR(core_parent))
1232 return 0;
1233
1234 if (get_links(core_parent, head->ctl_table, head->root))
1235 return 0;
1236
1237 core_parent->header.nreg++;
1238 spin_unlock(&sysctl_lock);
1239
1240 links = new_links(core_parent, head->ctl_table, head->root);
1241
1242 spin_lock(&sysctl_lock);
1243 err = -ENOMEM;
1244 if (!links)
1245 goto out;
1246
1247 err = 0;
1248 if (get_links(core_parent, head->ctl_table, head->root)) {
1249 kfree(links);
1250 goto out;
1251 }
1252
1253 err = insert_header(core_parent, links);
1254 if (err)
1255 kfree(links);
1256out:
1257 drop_sysctl_table(&core_parent->header);
1258 return err;
1259}
1260
1261/**
1262 * __register_sysctl_table - register a leaf sysctl table
1263 * @set: Sysctl tree to register on
1264 * @path: The path to the directory the sysctl table is in.
1265 * @table: the top-level table structure
1266 *
1267 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1268 * array. A completely 0 filled entry terminates the table.
1269 *
1270 * The members of the &struct ctl_table structure are used as follows:
1271 *
1272 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1273 * enter a sysctl file
1274 *
1275 * data - a pointer to data for use by proc_handler
1276 *
1277 * maxlen - the maximum size in bytes of the data
1278 *
1279 * mode - the file permissions for the /proc/sys file
1280 *
1281 * child - must be %NULL.
1282 *
1283 * proc_handler - the text handler routine (described below)
1284 *
1285 * extra1, extra2 - extra pointers usable by the proc handler routines
1286 *
1287 * Leaf nodes in the sysctl tree will be represented by a single file
1288 * under /proc; non-leaf nodes will be represented by directories.
1289 *
1290 * There must be a proc_handler routine for any terminal nodes.
1291 * Several default handlers are available to cover common cases -
1292 *
1293 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1294 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1295 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1296 *
1297 * It is the handler's job to read the input buffer from user memory
1298 * and process it. The handler should return 0 on success.
1299 *
1300 * This routine returns %NULL on a failure to register, and a pointer
1301 * to the table header on success.
1302 */
1303struct ctl_table_header *__register_sysctl_table(
1304 struct ctl_table_set *set,
1305 const char *path, struct ctl_table *table)
1306{
1307 struct ctl_table_root *root = set->dir.header.root;
1308 struct ctl_table_header *header;
1309 const char *name, *nextname;
1310 struct ctl_dir *dir;
1311 struct ctl_table *entry;
1312 struct ctl_node *node;
1313 int nr_entries = 0;
1314
1315 for (entry = table; entry->procname; entry++)
1316 nr_entries++;
1317
1318 header = kzalloc(sizeof(struct ctl_table_header) +
1319 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1320 if (!header)
1321 return NULL;
1322
1323 node = (struct ctl_node *)(header + 1);
1324 init_header(header, root, set, node, table);
1325 if (sysctl_check_table(path, table))
1326 goto fail;
1327
1328 spin_lock(&sysctl_lock);
1329 dir = &set->dir;
1330 /* Reference moved down the diretory tree get_subdir */
1331 dir->header.nreg++;
1332 spin_unlock(&sysctl_lock);
1333
1334 /* Find the directory for the ctl_table */
1335 for (name = path; name; name = nextname) {
1336 int namelen;
1337 nextname = strchr(name, '/');
1338 if (nextname) {
1339 namelen = nextname - name;
1340 nextname++;
1341 } else {
1342 namelen = strlen(name);
1343 }
1344 if (namelen == 0)
1345 continue;
1346
1347 dir = get_subdir(dir, name, namelen);
1348 if (IS_ERR(dir))
1349 goto fail;
1350 }
1351
1352 spin_lock(&sysctl_lock);
1353 if (insert_header(dir, header))
1354 goto fail_put_dir_locked;
1355
1356 drop_sysctl_table(&dir->header);
1357 spin_unlock(&sysctl_lock);
1358
1359 return header;
1360
1361fail_put_dir_locked:
1362 drop_sysctl_table(&dir->header);
1363 spin_unlock(&sysctl_lock);
1364fail:
1365 kfree(header);
1366 dump_stack();
1367 return NULL;
1368}
1369
1370/**
1371 * register_sysctl - register a sysctl table
1372 * @path: The path to the directory the sysctl table is in.
1373 * @table: the table structure
1374 *
1375 * Register a sysctl table. @table should be a filled in ctl_table
1376 * array. A completely 0 filled entry terminates the table.
1377 *
1378 * See __register_sysctl_table for more details.
1379 */
1380struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1381{
1382 return __register_sysctl_table(&sysctl_table_root.default_set,
1383 path, table);
1384}
1385EXPORT_SYMBOL(register_sysctl);
1386
1387static char *append_path(const char *path, char *pos, const char *name)
1388{
1389 int namelen;
1390 namelen = strlen(name);
1391 if (((pos - path) + namelen + 2) >= PATH_MAX)
1392 return NULL;
1393 memcpy(pos, name, namelen);
1394 pos[namelen] = '/';
1395 pos[namelen + 1] = '\0';
1396 pos += namelen + 1;
1397 return pos;
1398}
1399
1400static int count_subheaders(struct ctl_table *table)
1401{
1402 int has_files = 0;
1403 int nr_subheaders = 0;
1404 struct ctl_table *entry;
1405
1406 /* special case: no directory and empty directory */
1407 if (!table || !table->procname)
1408 return 1;
1409
1410 for (entry = table; entry->procname; entry++) {
1411 if (entry->child)
1412 nr_subheaders += count_subheaders(entry->child);
1413 else
1414 has_files = 1;
1415 }
1416 return nr_subheaders + has_files;
1417}
1418
1419static int register_leaf_sysctl_tables(const char *path, char *pos,
1420 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1421 struct ctl_table *table)
1422{
1423 struct ctl_table *ctl_table_arg = NULL;
1424 struct ctl_table *entry, *files;
1425 int nr_files = 0;
1426 int nr_dirs = 0;
1427 int err = -ENOMEM;
1428
1429 for (entry = table; entry->procname; entry++) {
1430 if (entry->child)
1431 nr_dirs++;
1432 else
1433 nr_files++;
1434 }
1435
1436 files = table;
1437 /* If there are mixed files and directories we need a new table */
1438 if (nr_dirs && nr_files) {
1439 struct ctl_table *new;
1440 files = kcalloc(nr_files + 1, sizeof(struct ctl_table),
1441 GFP_KERNEL);
1442 if (!files)
1443 goto out;
1444
1445 ctl_table_arg = files;
1446 for (new = files, entry = table; entry->procname; entry++) {
1447 if (entry->child)
1448 continue;
1449 *new = *entry;
1450 new++;
1451 }
1452 }
1453
1454 /* Register everything except a directory full of subdirectories */
1455 if (nr_files || !nr_dirs) {
1456 struct ctl_table_header *header;
1457 header = __register_sysctl_table(set, path, files);
1458 if (!header) {
1459 kfree(ctl_table_arg);
1460 goto out;
1461 }
1462
1463 /* Remember if we need to free the file table */
1464 header->ctl_table_arg = ctl_table_arg;
1465 **subheader = header;
1466 (*subheader)++;
1467 }
1468
1469 /* Recurse into the subdirectories. */
1470 for (entry = table; entry->procname; entry++) {
1471 char *child_pos;
1472
1473 if (!entry->child)
1474 continue;
1475
1476 err = -ENAMETOOLONG;
1477 child_pos = append_path(path, pos, entry->procname);
1478 if (!child_pos)
1479 goto out;
1480
1481 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1482 set, entry->child);
1483 pos[0] = '\0';
1484 if (err)
1485 goto out;
1486 }
1487 err = 0;
1488out:
1489 /* On failure our caller will unregister all registered subheaders */
1490 return err;
1491}
1492
1493/**
1494 * __register_sysctl_paths - register a sysctl table hierarchy
1495 * @set: Sysctl tree to register on
1496 * @path: The path to the directory the sysctl table is in.
1497 * @table: the top-level table structure
1498 *
1499 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1500 * array. A completely 0 filled entry terminates the table.
1501 *
1502 * See __register_sysctl_table for more details.
1503 */
1504struct ctl_table_header *__register_sysctl_paths(
1505 struct ctl_table_set *set,
1506 const struct ctl_path *path, struct ctl_table *table)
1507{
1508 struct ctl_table *ctl_table_arg = table;
1509 int nr_subheaders = count_subheaders(table);
1510 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1511 const struct ctl_path *component;
1512 char *new_path, *pos;
1513
1514 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1515 if (!new_path)
1516 return NULL;
1517
1518 pos[0] = '\0';
1519 for (component = path; component->procname; component++) {
1520 pos = append_path(new_path, pos, component->procname);
1521 if (!pos)
1522 goto out;
1523 }
1524 while (table->procname && table->child && !table[1].procname) {
1525 pos = append_path(new_path, pos, table->procname);
1526 if (!pos)
1527 goto out;
1528 table = table->child;
1529 }
1530 if (nr_subheaders == 1) {
1531 header = __register_sysctl_table(set, new_path, table);
1532 if (header)
1533 header->ctl_table_arg = ctl_table_arg;
1534 } else {
1535 header = kzalloc(sizeof(*header) +
1536 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1537 if (!header)
1538 goto out;
1539
1540 subheaders = (struct ctl_table_header **) (header + 1);
1541 subheader = subheaders;
1542 header->ctl_table_arg = ctl_table_arg;
1543
1544 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1545 set, table))
1546 goto err_register_leaves;
1547 }
1548
1549out:
1550 kfree(new_path);
1551 return header;
1552
1553err_register_leaves:
1554 while (subheader > subheaders) {
1555 struct ctl_table_header *subh = *(--subheader);
1556 struct ctl_table *table = subh->ctl_table_arg;
1557 unregister_sysctl_table(subh);
1558 kfree(table);
1559 }
1560 kfree(header);
1561 header = NULL;
1562 goto out;
1563}
1564
1565/**
1566 * register_sysctl_paths - register a sysctl table hierarchy
1567 * @path: The path to the directory the sysctl table is in.
1568 * @table: the top-level table structure
1569 *
1570 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1571 * array. A completely 0 filled entry terminates the table.
1572 *
1573 * See __register_sysctl_paths for more details.
1574 */
1575struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1576 struct ctl_table *table)
1577{
1578 return __register_sysctl_paths(&sysctl_table_root.default_set,
1579 path, table);
1580}
1581EXPORT_SYMBOL(register_sysctl_paths);
1582
1583/**
1584 * register_sysctl_table - register a sysctl table hierarchy
1585 * @table: the top-level table structure
1586 *
1587 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1588 * array. A completely 0 filled entry terminates the table.
1589 *
1590 * See register_sysctl_paths for more details.
1591 */
1592struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1593{
1594 static const struct ctl_path null_path[] = { {} };
1595
1596 return register_sysctl_paths(null_path, table);
1597}
1598EXPORT_SYMBOL(register_sysctl_table);
1599
1600static void put_links(struct ctl_table_header *header)
1601{
1602 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1603 struct ctl_table_root *root = header->root;
1604 struct ctl_dir *parent = header->parent;
1605 struct ctl_dir *core_parent;
1606 struct ctl_table *entry;
1607
1608 if (header->set == root_set)
1609 return;
1610
1611 core_parent = xlate_dir(root_set, parent);
1612 if (IS_ERR(core_parent))
1613 return;
1614
1615 for (entry = header->ctl_table; entry->procname; entry++) {
1616 struct ctl_table_header *link_head;
1617 struct ctl_table *link;
1618 const char *name = entry->procname;
1619
1620 link = find_entry(&link_head, core_parent, name, strlen(name));
1621 if (link &&
1622 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1623 (S_ISLNK(link->mode) && (link->data == root)))) {
1624 drop_sysctl_table(link_head);
1625 }
1626 else {
1627 pr_err("sysctl link missing during unregister: ");
1628 sysctl_print_dir(parent);
1629 pr_cont("/%s\n", name);
1630 }
1631 }
1632}
1633
1634static void drop_sysctl_table(struct ctl_table_header *header)
1635{
1636 struct ctl_dir *parent = header->parent;
1637
1638 if (--header->nreg)
1639 return;
1640
1641 if (parent) {
1642 put_links(header);
1643 start_unregistering(header);
1644 }
1645
1646 if (!--header->count)
1647 kfree_rcu(header, rcu);
1648
1649 if (parent)
1650 drop_sysctl_table(&parent->header);
1651}
1652
1653/**
1654 * unregister_sysctl_table - unregister a sysctl table hierarchy
1655 * @header: the header returned from register_sysctl_table
1656 *
1657 * Unregisters the sysctl table and all children. proc entries may not
1658 * actually be removed until they are no longer used by anyone.
1659 */
1660void unregister_sysctl_table(struct ctl_table_header * header)
1661{
1662 int nr_subheaders;
1663 might_sleep();
1664
1665 if (header == NULL)
1666 return;
1667
1668 nr_subheaders = count_subheaders(header->ctl_table_arg);
1669 if (unlikely(nr_subheaders > 1)) {
1670 struct ctl_table_header **subheaders;
1671 int i;
1672
1673 subheaders = (struct ctl_table_header **)(header + 1);
1674 for (i = nr_subheaders -1; i >= 0; i--) {
1675 struct ctl_table_header *subh = subheaders[i];
1676 struct ctl_table *table = subh->ctl_table_arg;
1677 unregister_sysctl_table(subh);
1678 kfree(table);
1679 }
1680 kfree(header);
1681 return;
1682 }
1683
1684 spin_lock(&sysctl_lock);
1685 drop_sysctl_table(header);
1686 spin_unlock(&sysctl_lock);
1687}
1688EXPORT_SYMBOL(unregister_sysctl_table);
1689
1690void setup_sysctl_set(struct ctl_table_set *set,
1691 struct ctl_table_root *root,
1692 int (*is_seen)(struct ctl_table_set *))
1693{
1694 memset(set, 0, sizeof(*set));
1695 set->is_seen = is_seen;
1696 init_header(&set->dir.header, root, set, NULL, root_table);
1697}
1698
1699void retire_sysctl_set(struct ctl_table_set *set)
1700{
1701 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1702}
1703
1704int __init proc_sys_init(void)
1705{
1706 struct proc_dir_entry *proc_sys_root;
1707
1708 proc_sys_root = proc_mkdir("sys", NULL);
1709 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1710 proc_sys_root->proc_dir_ops = &proc_sys_dir_file_operations;
1711 proc_sys_root->nlink = 0;
1712
1713 return sysctl_init();
1714}
1715
1716struct sysctl_alias {
1717 const char *kernel_param;
1718 const char *sysctl_param;
1719};
1720
1721/*
1722 * Historically some settings had both sysctl and a command line parameter.
1723 * With the generic sysctl. parameter support, we can handle them at a single
1724 * place and only keep the historical name for compatibility. This is not meant
1725 * to add brand new aliases. When adding existing aliases, consider whether
1726 * the possibly different moment of changing the value (e.g. from early_param
1727 * to the moment do_sysctl_args() is called) is an issue for the specific
1728 * parameter.
1729 */
1730static const struct sysctl_alias sysctl_aliases[] = {
1731 {"hardlockup_all_cpu_backtrace", "kernel.hardlockup_all_cpu_backtrace" },
1732 {"hung_task_panic", "kernel.hung_task_panic" },
1733 {"numa_zonelist_order", "vm.numa_zonelist_order" },
1734 {"softlockup_all_cpu_backtrace", "kernel.softlockup_all_cpu_backtrace" },
1735 {"softlockup_panic", "kernel.softlockup_panic" },
1736 { }
1737};
1738
1739static const char *sysctl_find_alias(char *param)
1740{
1741 const struct sysctl_alias *alias;
1742
1743 for (alias = &sysctl_aliases[0]; alias->kernel_param != NULL; alias++) {
1744 if (strcmp(alias->kernel_param, param) == 0)
1745 return alias->sysctl_param;
1746 }
1747
1748 return NULL;
1749}
1750
1751/* Set sysctl value passed on kernel command line. */
1752static int process_sysctl_arg(char *param, char *val,
1753 const char *unused, void *arg)
1754{
1755 char *path;
1756 struct vfsmount **proc_mnt = arg;
1757 struct file_system_type *proc_fs_type;
1758 struct file *file;
1759 int len;
1760 int err;
1761 loff_t pos = 0;
1762 ssize_t wret;
1763
1764 if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {
1765 param += sizeof("sysctl") - 1;
1766
1767 if (param[0] != '/' && param[0] != '.')
1768 return 0;
1769
1770 param++;
1771 } else {
1772 param = (char *) sysctl_find_alias(param);
1773 if (!param)
1774 return 0;
1775 }
1776
1777 if (!val)
1778 return -EINVAL;
1779 len = strlen(val);
1780 if (len == 0)
1781 return -EINVAL;
1782
1783 /*
1784 * To set sysctl options, we use a temporary mount of proc, look up the
1785 * respective sys/ file and write to it. To avoid mounting it when no
1786 * options were given, we mount it only when the first sysctl option is
1787 * found. Why not a persistent mount? There are problems with a
1788 * persistent mount of proc in that it forces userspace not to use any
1789 * proc mount options.
1790 */
1791 if (!*proc_mnt) {
1792 proc_fs_type = get_fs_type("proc");
1793 if (!proc_fs_type) {
1794 pr_err("Failed to find procfs to set sysctl from command line\n");
1795 return 0;
1796 }
1797 *proc_mnt = kern_mount(proc_fs_type);
1798 put_filesystem(proc_fs_type);
1799 if (IS_ERR(*proc_mnt)) {
1800 pr_err("Failed to mount procfs to set sysctl from command line\n");
1801 return 0;
1802 }
1803 }
1804
1805 path = kasprintf(GFP_KERNEL, "sys/%s", param);
1806 if (!path)
1807 panic("%s: Failed to allocate path for %s\n", __func__, param);
1808 strreplace(path, '.', '/');
1809
1810 file = file_open_root_mnt(*proc_mnt, path, O_WRONLY, 0);
1811 if (IS_ERR(file)) {
1812 err = PTR_ERR(file);
1813 if (err == -ENOENT)
1814 pr_err("Failed to set sysctl parameter '%s=%s': parameter not found\n",
1815 param, val);
1816 else if (err == -EACCES)
1817 pr_err("Failed to set sysctl parameter '%s=%s': permission denied (read-only?)\n",
1818 param, val);
1819 else
1820 pr_err("Error %pe opening proc file to set sysctl parameter '%s=%s'\n",
1821 file, param, val);
1822 goto out;
1823 }
1824 wret = kernel_write(file, val, len, &pos);
1825 if (wret < 0) {
1826 err = wret;
1827 if (err == -EINVAL)
1828 pr_err("Failed to set sysctl parameter '%s=%s': invalid value\n",
1829 param, val);
1830 else
1831 pr_err("Error %pe writing to proc file to set sysctl parameter '%s=%s'\n",
1832 ERR_PTR(err), param, val);
1833 } else if (wret != len) {
1834 pr_err("Wrote only %zd bytes of %d writing to proc file %s to set sysctl parameter '%s=%s\n",
1835 wret, len, path, param, val);
1836 }
1837
1838 err = filp_close(file, NULL);
1839 if (err)
1840 pr_err("Error %pe closing proc file to set sysctl parameter '%s=%s\n",
1841 ERR_PTR(err), param, val);
1842out:
1843 kfree(path);
1844 return 0;
1845}
1846
1847void do_sysctl_args(void)
1848{
1849 char *command_line;
1850 struct vfsmount *proc_mnt = NULL;
1851
1852 command_line = kstrdup(saved_command_line, GFP_KERNEL);
1853 if (!command_line)
1854 panic("%s: Failed to allocate copy of command line\n", __func__);
1855
1856 parse_args("Setting sysctl args", command_line,
1857 NULL, 0, -1, -1, &proc_mnt, process_sysctl_arg);
1858
1859 if (proc_mnt)
1860 kern_unmount(proc_mnt);
1861
1862 kfree(command_line);
1863}
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}