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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 <linux/kmemleak.h>
20#include "internal.h"
21
22#define list_for_each_table_entry(entry, header) \
23 entry = header->ctl_table; \
24 for (size_t i = 0 ; i < header->ctl_table_size && entry->procname; ++i, entry++)
25
26static const struct dentry_operations proc_sys_dentry_operations;
27static const struct file_operations proc_sys_file_operations;
28static const struct inode_operations proc_sys_inode_operations;
29static const struct file_operations proc_sys_dir_file_operations;
30static const struct inode_operations proc_sys_dir_operations;
31
32/* Support for permanently empty directories */
33static struct ctl_table sysctl_mount_point[] = {
34 {.type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY }
35};
36
37/**
38 * register_sysctl_mount_point() - registers a sysctl mount point
39 * @path: path for the mount point
40 *
41 * Used to create a permanently empty directory to serve as mount point.
42 * There are some subtle but important permission checks this allows in the
43 * case of unprivileged mounts.
44 */
45struct ctl_table_header *register_sysctl_mount_point(const char *path)
46{
47 return register_sysctl(path, sysctl_mount_point);
48}
49EXPORT_SYMBOL(register_sysctl_mount_point);
50
51#define sysctl_is_perm_empty_ctl_table(tptr) \
52 (tptr[0].type == SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
53#define sysctl_is_perm_empty_ctl_header(hptr) \
54 (sysctl_is_perm_empty_ctl_table(hptr->ctl_table))
55#define sysctl_set_perm_empty_ctl_header(hptr) \
56 (hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
57#define sysctl_clear_perm_empty_ctl_header(hptr) \
58 (hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_DEFAULT)
59
60void proc_sys_poll_notify(struct ctl_table_poll *poll)
61{
62 if (!poll)
63 return;
64
65 atomic_inc(&poll->event);
66 wake_up_interruptible(&poll->wait);
67}
68
69static struct ctl_table root_table[] = {
70 {
71 .procname = "",
72 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
73 },
74};
75static struct ctl_table_root sysctl_table_root = {
76 .default_set.dir.header = {
77 {{.count = 1,
78 .nreg = 1,
79 .ctl_table = root_table }},
80 .ctl_table_arg = root_table,
81 .root = &sysctl_table_root,
82 .set = &sysctl_table_root.default_set,
83 },
84};
85
86static DEFINE_SPINLOCK(sysctl_lock);
87
88static void drop_sysctl_table(struct ctl_table_header *header);
89static int sysctl_follow_link(struct ctl_table_header **phead,
90 struct ctl_table **pentry);
91static int insert_links(struct ctl_table_header *head);
92static void put_links(struct ctl_table_header *header);
93
94static void sysctl_print_dir(struct ctl_dir *dir)
95{
96 if (dir->header.parent)
97 sysctl_print_dir(dir->header.parent);
98 pr_cont("%s/", dir->header.ctl_table[0].procname);
99}
100
101static int namecmp(const char *name1, int len1, const char *name2, int len2)
102{
103 int cmp;
104
105 cmp = memcmp(name1, name2, min(len1, len2));
106 if (cmp == 0)
107 cmp = len1 - len2;
108 return cmp;
109}
110
111/* Called under sysctl_lock */
112static struct ctl_table *find_entry(struct ctl_table_header **phead,
113 struct ctl_dir *dir, const char *name, int namelen)
114{
115 struct ctl_table_header *head;
116 struct ctl_table *entry;
117 struct rb_node *node = dir->root.rb_node;
118
119 while (node)
120 {
121 struct ctl_node *ctl_node;
122 const char *procname;
123 int cmp;
124
125 ctl_node = rb_entry(node, struct ctl_node, node);
126 head = ctl_node->header;
127 entry = &head->ctl_table[ctl_node - head->node];
128 procname = entry->procname;
129
130 cmp = namecmp(name, namelen, procname, strlen(procname));
131 if (cmp < 0)
132 node = node->rb_left;
133 else if (cmp > 0)
134 node = node->rb_right;
135 else {
136 *phead = head;
137 return entry;
138 }
139 }
140 return NULL;
141}
142
143static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
144{
145 struct rb_node *node = &head->node[entry - head->ctl_table].node;
146 struct rb_node **p = &head->parent->root.rb_node;
147 struct rb_node *parent = NULL;
148 const char *name = entry->procname;
149 int namelen = strlen(name);
150
151 while (*p) {
152 struct ctl_table_header *parent_head;
153 struct ctl_table *parent_entry;
154 struct ctl_node *parent_node;
155 const char *parent_name;
156 int cmp;
157
158 parent = *p;
159 parent_node = rb_entry(parent, struct ctl_node, node);
160 parent_head = parent_node->header;
161 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
162 parent_name = parent_entry->procname;
163
164 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
165 if (cmp < 0)
166 p = &(*p)->rb_left;
167 else if (cmp > 0)
168 p = &(*p)->rb_right;
169 else {
170 pr_err("sysctl duplicate entry: ");
171 sysctl_print_dir(head->parent);
172 pr_cont("%s\n", entry->procname);
173 return -EEXIST;
174 }
175 }
176
177 rb_link_node(node, parent, p);
178 rb_insert_color(node, &head->parent->root);
179 return 0;
180}
181
182static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
183{
184 struct rb_node *node = &head->node[entry - head->ctl_table].node;
185
186 rb_erase(node, &head->parent->root);
187}
188
189static void init_header(struct ctl_table_header *head,
190 struct ctl_table_root *root, struct ctl_table_set *set,
191 struct ctl_node *node, struct ctl_table *table, size_t table_size)
192{
193 head->ctl_table = table;
194 head->ctl_table_size = table_size;
195 head->ctl_table_arg = table;
196 head->used = 0;
197 head->count = 1;
198 head->nreg = 1;
199 head->unregistering = NULL;
200 head->root = root;
201 head->set = set;
202 head->parent = NULL;
203 head->node = node;
204 INIT_HLIST_HEAD(&head->inodes);
205 if (node) {
206 struct ctl_table *entry;
207
208 list_for_each_table_entry(entry, head) {
209 node->header = head;
210 node++;
211 }
212 }
213}
214
215static void erase_header(struct ctl_table_header *head)
216{
217 struct ctl_table *entry;
218
219 list_for_each_table_entry(entry, head)
220 erase_entry(head, entry);
221}
222
223static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
224{
225 struct ctl_table *entry;
226 struct ctl_table_header *dir_h = &dir->header;
227 int err;
228
229
230 /* Is this a permanently empty directory? */
231 if (sysctl_is_perm_empty_ctl_header(dir_h))
232 return -EROFS;
233
234 /* Am I creating a permanently empty directory? */
235 if (header->ctl_table_size > 0 &&
236 sysctl_is_perm_empty_ctl_table(header->ctl_table)) {
237 if (!RB_EMPTY_ROOT(&dir->root))
238 return -EINVAL;
239 sysctl_set_perm_empty_ctl_header(dir_h);
240 }
241
242 dir_h->nreg++;
243 header->parent = dir;
244 err = insert_links(header);
245 if (err)
246 goto fail_links;
247 list_for_each_table_entry(entry, header) {
248 err = insert_entry(header, entry);
249 if (err)
250 goto fail;
251 }
252 return 0;
253fail:
254 erase_header(header);
255 put_links(header);
256fail_links:
257 if (header->ctl_table == sysctl_mount_point)
258 sysctl_clear_perm_empty_ctl_header(dir_h);
259 header->parent = NULL;
260 drop_sysctl_table(dir_h);
261 return err;
262}
263
264/* called under sysctl_lock */
265static int use_table(struct ctl_table_header *p)
266{
267 if (unlikely(p->unregistering))
268 return 0;
269 p->used++;
270 return 1;
271}
272
273/* called under sysctl_lock */
274static void unuse_table(struct ctl_table_header *p)
275{
276 if (!--p->used)
277 if (unlikely(p->unregistering))
278 complete(p->unregistering);
279}
280
281static void proc_sys_invalidate_dcache(struct ctl_table_header *head)
282{
283 proc_invalidate_siblings_dcache(&head->inodes, &sysctl_lock);
284}
285
286/* called under sysctl_lock, will reacquire if has to wait */
287static void start_unregistering(struct ctl_table_header *p)
288{
289 /*
290 * if p->used is 0, nobody will ever touch that entry again;
291 * we'll eliminate all paths to it before dropping sysctl_lock
292 */
293 if (unlikely(p->used)) {
294 struct completion wait;
295 init_completion(&wait);
296 p->unregistering = &wait;
297 spin_unlock(&sysctl_lock);
298 wait_for_completion(&wait);
299 } else {
300 /* anything non-NULL; we'll never dereference it */
301 p->unregistering = ERR_PTR(-EINVAL);
302 spin_unlock(&sysctl_lock);
303 }
304 /*
305 * Invalidate dentries for unregistered sysctls: namespaced sysctls
306 * can have duplicate names and contaminate dcache very badly.
307 */
308 proc_sys_invalidate_dcache(p);
309 /*
310 * do not remove from the list until nobody holds it; walking the
311 * list in do_sysctl() relies on that.
312 */
313 spin_lock(&sysctl_lock);
314 erase_header(p);
315}
316
317static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
318{
319 BUG_ON(!head);
320 spin_lock(&sysctl_lock);
321 if (!use_table(head))
322 head = ERR_PTR(-ENOENT);
323 spin_unlock(&sysctl_lock);
324 return head;
325}
326
327static void sysctl_head_finish(struct ctl_table_header *head)
328{
329 if (!head)
330 return;
331 spin_lock(&sysctl_lock);
332 unuse_table(head);
333 spin_unlock(&sysctl_lock);
334}
335
336static struct ctl_table_set *
337lookup_header_set(struct ctl_table_root *root)
338{
339 struct ctl_table_set *set = &root->default_set;
340 if (root->lookup)
341 set = root->lookup(root);
342 return set;
343}
344
345static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
346 struct ctl_dir *dir,
347 const char *name, int namelen)
348{
349 struct ctl_table_header *head;
350 struct ctl_table *entry;
351
352 spin_lock(&sysctl_lock);
353 entry = find_entry(&head, dir, name, namelen);
354 if (entry && use_table(head))
355 *phead = head;
356 else
357 entry = NULL;
358 spin_unlock(&sysctl_lock);
359 return entry;
360}
361
362static struct ctl_node *first_usable_entry(struct rb_node *node)
363{
364 struct ctl_node *ctl_node;
365
366 for (;node; node = rb_next(node)) {
367 ctl_node = rb_entry(node, struct ctl_node, node);
368 if (use_table(ctl_node->header))
369 return ctl_node;
370 }
371 return NULL;
372}
373
374static void first_entry(struct ctl_dir *dir,
375 struct ctl_table_header **phead, struct ctl_table **pentry)
376{
377 struct ctl_table_header *head = NULL;
378 struct ctl_table *entry = NULL;
379 struct ctl_node *ctl_node;
380
381 spin_lock(&sysctl_lock);
382 ctl_node = first_usable_entry(rb_first(&dir->root));
383 spin_unlock(&sysctl_lock);
384 if (ctl_node) {
385 head = ctl_node->header;
386 entry = &head->ctl_table[ctl_node - head->node];
387 }
388 *phead = head;
389 *pentry = entry;
390}
391
392static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
393{
394 struct ctl_table_header *head = *phead;
395 struct ctl_table *entry = *pentry;
396 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
397
398 spin_lock(&sysctl_lock);
399 unuse_table(head);
400
401 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
402 spin_unlock(&sysctl_lock);
403 head = NULL;
404 if (ctl_node) {
405 head = ctl_node->header;
406 entry = &head->ctl_table[ctl_node - head->node];
407 }
408 *phead = head;
409 *pentry = entry;
410}
411
412/*
413 * sysctl_perm does NOT grant the superuser all rights automatically, because
414 * some sysctl variables are readonly even to root.
415 */
416
417static int test_perm(int mode, int op)
418{
419 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
420 mode >>= 6;
421 else if (in_egroup_p(GLOBAL_ROOT_GID))
422 mode >>= 3;
423 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
424 return 0;
425 return -EACCES;
426}
427
428static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
429{
430 struct ctl_table_root *root = head->root;
431 int mode;
432
433 if (root->permissions)
434 mode = root->permissions(head, table);
435 else
436 mode = table->mode;
437
438 return test_perm(mode, op);
439}
440
441static struct inode *proc_sys_make_inode(struct super_block *sb,
442 struct ctl_table_header *head, struct ctl_table *table)
443{
444 struct ctl_table_root *root = head->root;
445 struct inode *inode;
446 struct proc_inode *ei;
447
448 inode = new_inode(sb);
449 if (!inode)
450 return ERR_PTR(-ENOMEM);
451
452 inode->i_ino = get_next_ino();
453
454 ei = PROC_I(inode);
455
456 spin_lock(&sysctl_lock);
457 if (unlikely(head->unregistering)) {
458 spin_unlock(&sysctl_lock);
459 iput(inode);
460 return ERR_PTR(-ENOENT);
461 }
462 ei->sysctl = head;
463 ei->sysctl_entry = table;
464 hlist_add_head_rcu(&ei->sibling_inodes, &head->inodes);
465 head->count++;
466 spin_unlock(&sysctl_lock);
467
468 simple_inode_init_ts(inode);
469 inode->i_mode = table->mode;
470 if (!S_ISDIR(table->mode)) {
471 inode->i_mode |= S_IFREG;
472 inode->i_op = &proc_sys_inode_operations;
473 inode->i_fop = &proc_sys_file_operations;
474 } else {
475 inode->i_mode |= S_IFDIR;
476 inode->i_op = &proc_sys_dir_operations;
477 inode->i_fop = &proc_sys_dir_file_operations;
478 if (sysctl_is_perm_empty_ctl_header(head))
479 make_empty_dir_inode(inode);
480 }
481
482 if (root->set_ownership)
483 root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
484 else {
485 inode->i_uid = GLOBAL_ROOT_UID;
486 inode->i_gid = GLOBAL_ROOT_GID;
487 }
488
489 return inode;
490}
491
492void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
493{
494 spin_lock(&sysctl_lock);
495 hlist_del_init_rcu(&PROC_I(inode)->sibling_inodes);
496 if (!--head->count)
497 kfree_rcu(head, rcu);
498 spin_unlock(&sysctl_lock);
499}
500
501static struct ctl_table_header *grab_header(struct inode *inode)
502{
503 struct ctl_table_header *head = PROC_I(inode)->sysctl;
504 if (!head)
505 head = &sysctl_table_root.default_set.dir.header;
506 return sysctl_head_grab(head);
507}
508
509static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
510 unsigned int flags)
511{
512 struct ctl_table_header *head = grab_header(dir);
513 struct ctl_table_header *h = NULL;
514 const struct qstr *name = &dentry->d_name;
515 struct ctl_table *p;
516 struct inode *inode;
517 struct dentry *err = ERR_PTR(-ENOENT);
518 struct ctl_dir *ctl_dir;
519 int ret;
520
521 if (IS_ERR(head))
522 return ERR_CAST(head);
523
524 ctl_dir = container_of(head, struct ctl_dir, header);
525
526 p = lookup_entry(&h, ctl_dir, name->name, name->len);
527 if (!p)
528 goto out;
529
530 if (S_ISLNK(p->mode)) {
531 ret = sysctl_follow_link(&h, &p);
532 err = ERR_PTR(ret);
533 if (ret)
534 goto out;
535 }
536
537 d_set_d_op(dentry, &proc_sys_dentry_operations);
538 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
539 err = d_splice_alias(inode, dentry);
540
541out:
542 if (h)
543 sysctl_head_finish(h);
544 sysctl_head_finish(head);
545 return err;
546}
547
548static ssize_t proc_sys_call_handler(struct kiocb *iocb, struct iov_iter *iter,
549 int write)
550{
551 struct inode *inode = file_inode(iocb->ki_filp);
552 struct ctl_table_header *head = grab_header(inode);
553 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
554 size_t count = iov_iter_count(iter);
555 char *kbuf;
556 ssize_t error;
557
558 if (IS_ERR(head))
559 return PTR_ERR(head);
560
561 /*
562 * At this point we know that the sysctl was not unregistered
563 * and won't be until we finish.
564 */
565 error = -EPERM;
566 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
567 goto out;
568
569 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
570 error = -EINVAL;
571 if (!table->proc_handler)
572 goto out;
573
574 /* don't even try if the size is too large */
575 error = -ENOMEM;
576 if (count >= KMALLOC_MAX_SIZE)
577 goto out;
578 kbuf = kvzalloc(count + 1, GFP_KERNEL);
579 if (!kbuf)
580 goto out;
581
582 if (write) {
583 error = -EFAULT;
584 if (!copy_from_iter_full(kbuf, count, iter))
585 goto out_free_buf;
586 kbuf[count] = '\0';
587 }
588
589 error = BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, &kbuf, &count,
590 &iocb->ki_pos);
591 if (error)
592 goto out_free_buf;
593
594 /* careful: calling conventions are nasty here */
595 error = table->proc_handler(table, write, kbuf, &count, &iocb->ki_pos);
596 if (error)
597 goto out_free_buf;
598
599 if (!write) {
600 error = -EFAULT;
601 if (copy_to_iter(kbuf, count, iter) < count)
602 goto out_free_buf;
603 }
604
605 error = count;
606out_free_buf:
607 kvfree(kbuf);
608out:
609 sysctl_head_finish(head);
610
611 return error;
612}
613
614static ssize_t proc_sys_read(struct kiocb *iocb, struct iov_iter *iter)
615{
616 return proc_sys_call_handler(iocb, iter, 0);
617}
618
619static ssize_t proc_sys_write(struct kiocb *iocb, struct iov_iter *iter)
620{
621 return proc_sys_call_handler(iocb, iter, 1);
622}
623
624static int proc_sys_open(struct inode *inode, struct file *filp)
625{
626 struct ctl_table_header *head = grab_header(inode);
627 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
628
629 /* sysctl was unregistered */
630 if (IS_ERR(head))
631 return PTR_ERR(head);
632
633 if (table->poll)
634 filp->private_data = proc_sys_poll_event(table->poll);
635
636 sysctl_head_finish(head);
637
638 return 0;
639}
640
641static __poll_t proc_sys_poll(struct file *filp, poll_table *wait)
642{
643 struct inode *inode = file_inode(filp);
644 struct ctl_table_header *head = grab_header(inode);
645 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
646 __poll_t ret = DEFAULT_POLLMASK;
647 unsigned long event;
648
649 /* sysctl was unregistered */
650 if (IS_ERR(head))
651 return EPOLLERR | EPOLLHUP;
652
653 if (!table->proc_handler)
654 goto out;
655
656 if (!table->poll)
657 goto out;
658
659 event = (unsigned long)filp->private_data;
660 poll_wait(filp, &table->poll->wait, wait);
661
662 if (event != atomic_read(&table->poll->event)) {
663 filp->private_data = proc_sys_poll_event(table->poll);
664 ret = EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI;
665 }
666
667out:
668 sysctl_head_finish(head);
669
670 return ret;
671}
672
673static bool proc_sys_fill_cache(struct file *file,
674 struct dir_context *ctx,
675 struct ctl_table_header *head,
676 struct ctl_table *table)
677{
678 struct dentry *child, *dir = file->f_path.dentry;
679 struct inode *inode;
680 struct qstr qname;
681 ino_t ino = 0;
682 unsigned type = DT_UNKNOWN;
683
684 qname.name = table->procname;
685 qname.len = strlen(table->procname);
686 qname.hash = full_name_hash(dir, qname.name, qname.len);
687
688 child = d_lookup(dir, &qname);
689 if (!child) {
690 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
691 child = d_alloc_parallel(dir, &qname, &wq);
692 if (IS_ERR(child))
693 return false;
694 if (d_in_lookup(child)) {
695 struct dentry *res;
696 d_set_d_op(child, &proc_sys_dentry_operations);
697 inode = proc_sys_make_inode(dir->d_sb, head, table);
698 res = d_splice_alias(inode, child);
699 d_lookup_done(child);
700 if (unlikely(res)) {
701 if (IS_ERR(res)) {
702 dput(child);
703 return false;
704 }
705 dput(child);
706 child = res;
707 }
708 }
709 }
710 inode = d_inode(child);
711 ino = inode->i_ino;
712 type = inode->i_mode >> 12;
713 dput(child);
714 return dir_emit(ctx, qname.name, qname.len, ino, type);
715}
716
717static bool proc_sys_link_fill_cache(struct file *file,
718 struct dir_context *ctx,
719 struct ctl_table_header *head,
720 struct ctl_table *table)
721{
722 bool ret = true;
723
724 head = sysctl_head_grab(head);
725 if (IS_ERR(head))
726 return false;
727
728 /* It is not an error if we can not follow the link ignore it */
729 if (sysctl_follow_link(&head, &table))
730 goto out;
731
732 ret = proc_sys_fill_cache(file, ctx, head, table);
733out:
734 sysctl_head_finish(head);
735 return ret;
736}
737
738static int scan(struct ctl_table_header *head, struct ctl_table *table,
739 unsigned long *pos, struct file *file,
740 struct dir_context *ctx)
741{
742 bool res;
743
744 if ((*pos)++ < ctx->pos)
745 return true;
746
747 if (unlikely(S_ISLNK(table->mode)))
748 res = proc_sys_link_fill_cache(file, ctx, head, table);
749 else
750 res = proc_sys_fill_cache(file, ctx, head, table);
751
752 if (res)
753 ctx->pos = *pos;
754
755 return res;
756}
757
758static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
759{
760 struct ctl_table_header *head = grab_header(file_inode(file));
761 struct ctl_table_header *h = NULL;
762 struct ctl_table *entry;
763 struct ctl_dir *ctl_dir;
764 unsigned long pos;
765
766 if (IS_ERR(head))
767 return PTR_ERR(head);
768
769 ctl_dir = container_of(head, struct ctl_dir, header);
770
771 if (!dir_emit_dots(file, ctx))
772 goto out;
773
774 pos = 2;
775
776 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
777 if (!scan(h, entry, &pos, file, ctx)) {
778 sysctl_head_finish(h);
779 break;
780 }
781 }
782out:
783 sysctl_head_finish(head);
784 return 0;
785}
786
787static int proc_sys_permission(struct mnt_idmap *idmap,
788 struct inode *inode, int mask)
789{
790 /*
791 * sysctl entries that are not writeable,
792 * are _NOT_ writeable, capabilities or not.
793 */
794 struct ctl_table_header *head;
795 struct ctl_table *table;
796 int error;
797
798 /* Executable files are not allowed under /proc/sys/ */
799 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
800 return -EACCES;
801
802 head = grab_header(inode);
803 if (IS_ERR(head))
804 return PTR_ERR(head);
805
806 table = PROC_I(inode)->sysctl_entry;
807 if (!table) /* global root - r-xr-xr-x */
808 error = mask & MAY_WRITE ? -EACCES : 0;
809 else /* Use the permissions on the sysctl table entry */
810 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
811
812 sysctl_head_finish(head);
813 return error;
814}
815
816static int proc_sys_setattr(struct mnt_idmap *idmap,
817 struct dentry *dentry, struct iattr *attr)
818{
819 struct inode *inode = d_inode(dentry);
820 int error;
821
822 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
823 return -EPERM;
824
825 error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
826 if (error)
827 return error;
828
829 setattr_copy(&nop_mnt_idmap, inode, attr);
830 return 0;
831}
832
833static int proc_sys_getattr(struct mnt_idmap *idmap,
834 const struct path *path, struct kstat *stat,
835 u32 request_mask, unsigned int query_flags)
836{
837 struct inode *inode = d_inode(path->dentry);
838 struct ctl_table_header *head = grab_header(inode);
839 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
840
841 if (IS_ERR(head))
842 return PTR_ERR(head);
843
844 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
845 if (table)
846 stat->mode = (stat->mode & S_IFMT) | table->mode;
847
848 sysctl_head_finish(head);
849 return 0;
850}
851
852static const struct file_operations proc_sys_file_operations = {
853 .open = proc_sys_open,
854 .poll = proc_sys_poll,
855 .read_iter = proc_sys_read,
856 .write_iter = proc_sys_write,
857 .splice_read = copy_splice_read,
858 .splice_write = iter_file_splice_write,
859 .llseek = default_llseek,
860};
861
862static const struct file_operations proc_sys_dir_file_operations = {
863 .read = generic_read_dir,
864 .iterate_shared = proc_sys_readdir,
865 .llseek = generic_file_llseek,
866};
867
868static const struct inode_operations proc_sys_inode_operations = {
869 .permission = proc_sys_permission,
870 .setattr = proc_sys_setattr,
871 .getattr = proc_sys_getattr,
872};
873
874static const struct inode_operations proc_sys_dir_operations = {
875 .lookup = proc_sys_lookup,
876 .permission = proc_sys_permission,
877 .setattr = proc_sys_setattr,
878 .getattr = proc_sys_getattr,
879};
880
881static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
882{
883 if (flags & LOOKUP_RCU)
884 return -ECHILD;
885 return !PROC_I(d_inode(dentry))->sysctl->unregistering;
886}
887
888static int proc_sys_delete(const struct dentry *dentry)
889{
890 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
891}
892
893static int sysctl_is_seen(struct ctl_table_header *p)
894{
895 struct ctl_table_set *set = p->set;
896 int res;
897 spin_lock(&sysctl_lock);
898 if (p->unregistering)
899 res = 0;
900 else if (!set->is_seen)
901 res = 1;
902 else
903 res = set->is_seen(set);
904 spin_unlock(&sysctl_lock);
905 return res;
906}
907
908static int proc_sys_compare(const struct dentry *dentry,
909 unsigned int len, const char *str, const struct qstr *name)
910{
911 struct ctl_table_header *head;
912 struct inode *inode;
913
914 /* Although proc doesn't have negative dentries, rcu-walk means
915 * that inode here can be NULL */
916 /* AV: can it, indeed? */
917 inode = d_inode_rcu(dentry);
918 if (!inode)
919 return 1;
920 if (name->len != len)
921 return 1;
922 if (memcmp(name->name, str, len))
923 return 1;
924 head = rcu_dereference(PROC_I(inode)->sysctl);
925 return !head || !sysctl_is_seen(head);
926}
927
928static const struct dentry_operations proc_sys_dentry_operations = {
929 .d_revalidate = proc_sys_revalidate,
930 .d_delete = proc_sys_delete,
931 .d_compare = proc_sys_compare,
932};
933
934static struct ctl_dir *find_subdir(struct ctl_dir *dir,
935 const char *name, int namelen)
936{
937 struct ctl_table_header *head;
938 struct ctl_table *entry;
939
940 entry = find_entry(&head, dir, name, namelen);
941 if (!entry)
942 return ERR_PTR(-ENOENT);
943 if (!S_ISDIR(entry->mode))
944 return ERR_PTR(-ENOTDIR);
945 return container_of(head, struct ctl_dir, header);
946}
947
948static struct ctl_dir *new_dir(struct ctl_table_set *set,
949 const char *name, int namelen)
950{
951 struct ctl_table *table;
952 struct ctl_dir *new;
953 struct ctl_node *node;
954 char *new_name;
955
956 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
957 sizeof(struct ctl_table)*2 + namelen + 1,
958 GFP_KERNEL);
959 if (!new)
960 return NULL;
961
962 node = (struct ctl_node *)(new + 1);
963 table = (struct ctl_table *)(node + 1);
964 new_name = (char *)(table + 2);
965 memcpy(new_name, name, namelen);
966 table[0].procname = new_name;
967 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
968 init_header(&new->header, set->dir.header.root, set, node, table, 1);
969
970 return new;
971}
972
973/**
974 * get_subdir - find or create a subdir with the specified name.
975 * @dir: Directory to create the subdirectory in
976 * @name: The name of the subdirectory to find or create
977 * @namelen: The length of name
978 *
979 * Takes a directory with an elevated reference count so we know that
980 * if we drop the lock the directory will not go away. Upon success
981 * the reference is moved from @dir to the returned subdirectory.
982 * Upon error an error code is returned and the reference on @dir is
983 * simply dropped.
984 */
985static struct ctl_dir *get_subdir(struct ctl_dir *dir,
986 const char *name, int namelen)
987{
988 struct ctl_table_set *set = dir->header.set;
989 struct ctl_dir *subdir, *new = NULL;
990 int err;
991
992 spin_lock(&sysctl_lock);
993 subdir = find_subdir(dir, name, namelen);
994 if (!IS_ERR(subdir))
995 goto found;
996 if (PTR_ERR(subdir) != -ENOENT)
997 goto failed;
998
999 spin_unlock(&sysctl_lock);
1000 new = new_dir(set, name, namelen);
1001 spin_lock(&sysctl_lock);
1002 subdir = ERR_PTR(-ENOMEM);
1003 if (!new)
1004 goto failed;
1005
1006 /* Was the subdir added while we dropped the lock? */
1007 subdir = find_subdir(dir, name, namelen);
1008 if (!IS_ERR(subdir))
1009 goto found;
1010 if (PTR_ERR(subdir) != -ENOENT)
1011 goto failed;
1012
1013 /* Nope. Use the our freshly made directory entry. */
1014 err = insert_header(dir, &new->header);
1015 subdir = ERR_PTR(err);
1016 if (err)
1017 goto failed;
1018 subdir = new;
1019found:
1020 subdir->header.nreg++;
1021failed:
1022 if (IS_ERR(subdir)) {
1023 pr_err("sysctl could not get directory: ");
1024 sysctl_print_dir(dir);
1025 pr_cont("%*.*s %ld\n", namelen, namelen, name,
1026 PTR_ERR(subdir));
1027 }
1028 drop_sysctl_table(&dir->header);
1029 if (new)
1030 drop_sysctl_table(&new->header);
1031 spin_unlock(&sysctl_lock);
1032 return subdir;
1033}
1034
1035static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
1036{
1037 struct ctl_dir *parent;
1038 const char *procname;
1039 if (!dir->header.parent)
1040 return &set->dir;
1041 parent = xlate_dir(set, dir->header.parent);
1042 if (IS_ERR(parent))
1043 return parent;
1044 procname = dir->header.ctl_table[0].procname;
1045 return find_subdir(parent, procname, strlen(procname));
1046}
1047
1048static int sysctl_follow_link(struct ctl_table_header **phead,
1049 struct ctl_table **pentry)
1050{
1051 struct ctl_table_header *head;
1052 struct ctl_table_root *root;
1053 struct ctl_table_set *set;
1054 struct ctl_table *entry;
1055 struct ctl_dir *dir;
1056 int ret;
1057
1058 spin_lock(&sysctl_lock);
1059 root = (*pentry)->data;
1060 set = lookup_header_set(root);
1061 dir = xlate_dir(set, (*phead)->parent);
1062 if (IS_ERR(dir))
1063 ret = PTR_ERR(dir);
1064 else {
1065 const char *procname = (*pentry)->procname;
1066 head = NULL;
1067 entry = find_entry(&head, dir, procname, strlen(procname));
1068 ret = -ENOENT;
1069 if (entry && use_table(head)) {
1070 unuse_table(*phead);
1071 *phead = head;
1072 *pentry = entry;
1073 ret = 0;
1074 }
1075 }
1076
1077 spin_unlock(&sysctl_lock);
1078 return ret;
1079}
1080
1081static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
1082{
1083 struct va_format vaf;
1084 va_list args;
1085
1086 va_start(args, fmt);
1087 vaf.fmt = fmt;
1088 vaf.va = &args;
1089
1090 pr_err("sysctl table check failed: %s/%s %pV\n",
1091 path, table->procname, &vaf);
1092
1093 va_end(args);
1094 return -EINVAL;
1095}
1096
1097static int sysctl_check_table_array(const char *path, struct ctl_table *table)
1098{
1099 int err = 0;
1100
1101 if ((table->proc_handler == proc_douintvec) ||
1102 (table->proc_handler == proc_douintvec_minmax)) {
1103 if (table->maxlen != sizeof(unsigned int))
1104 err |= sysctl_err(path, table, "array not allowed");
1105 }
1106
1107 if (table->proc_handler == proc_dou8vec_minmax) {
1108 if (table->maxlen != sizeof(u8))
1109 err |= sysctl_err(path, table, "array not allowed");
1110 }
1111
1112 if (table->proc_handler == proc_dobool) {
1113 if (table->maxlen != sizeof(bool))
1114 err |= sysctl_err(path, table, "array not allowed");
1115 }
1116
1117 return err;
1118}
1119
1120static int sysctl_check_table(const char *path, struct ctl_table_header *header)
1121{
1122 struct ctl_table *entry;
1123 int err = 0;
1124 list_for_each_table_entry(entry, header) {
1125 if ((entry->proc_handler == proc_dostring) ||
1126 (entry->proc_handler == proc_dobool) ||
1127 (entry->proc_handler == proc_dointvec) ||
1128 (entry->proc_handler == proc_douintvec) ||
1129 (entry->proc_handler == proc_douintvec_minmax) ||
1130 (entry->proc_handler == proc_dointvec_minmax) ||
1131 (entry->proc_handler == proc_dou8vec_minmax) ||
1132 (entry->proc_handler == proc_dointvec_jiffies) ||
1133 (entry->proc_handler == proc_dointvec_userhz_jiffies) ||
1134 (entry->proc_handler == proc_dointvec_ms_jiffies) ||
1135 (entry->proc_handler == proc_doulongvec_minmax) ||
1136 (entry->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1137 if (!entry->data)
1138 err |= sysctl_err(path, entry, "No data");
1139 if (!entry->maxlen)
1140 err |= sysctl_err(path, entry, "No maxlen");
1141 else
1142 err |= sysctl_check_table_array(path, entry);
1143 }
1144 if (!entry->proc_handler)
1145 err |= sysctl_err(path, entry, "No proc_handler");
1146
1147 if ((entry->mode & (S_IRUGO|S_IWUGO)) != entry->mode)
1148 err |= sysctl_err(path, entry, "bogus .mode 0%o",
1149 entry->mode);
1150 }
1151 return err;
1152}
1153
1154static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_header *head)
1155{
1156 struct ctl_table *link_table, *entry, *link;
1157 struct ctl_table_header *links;
1158 struct ctl_node *node;
1159 char *link_name;
1160 int nr_entries, name_bytes;
1161
1162 name_bytes = 0;
1163 nr_entries = 0;
1164 list_for_each_table_entry(entry, head) {
1165 nr_entries++;
1166 name_bytes += strlen(entry->procname) + 1;
1167 }
1168
1169 links = kzalloc(sizeof(struct ctl_table_header) +
1170 sizeof(struct ctl_node)*nr_entries +
1171 sizeof(struct ctl_table)*(nr_entries + 1) +
1172 name_bytes,
1173 GFP_KERNEL);
1174
1175 if (!links)
1176 return NULL;
1177
1178 node = (struct ctl_node *)(links + 1);
1179 link_table = (struct ctl_table *)(node + nr_entries);
1180 link_name = (char *)&link_table[nr_entries + 1];
1181 link = link_table;
1182
1183 list_for_each_table_entry(entry, head) {
1184 int len = strlen(entry->procname) + 1;
1185 memcpy(link_name, entry->procname, len);
1186 link->procname = link_name;
1187 link->mode = S_IFLNK|S_IRWXUGO;
1188 link->data = head->root;
1189 link_name += len;
1190 link++;
1191 }
1192 init_header(links, dir->header.root, dir->header.set, node, link_table,
1193 head->ctl_table_size);
1194 links->nreg = nr_entries;
1195
1196 return links;
1197}
1198
1199static bool get_links(struct ctl_dir *dir,
1200 struct ctl_table_header *header,
1201 struct ctl_table_root *link_root)
1202{
1203 struct ctl_table_header *tmp_head;
1204 struct ctl_table *entry, *link;
1205
1206 if (header->ctl_table_size == 0 ||
1207 sysctl_is_perm_empty_ctl_table(header->ctl_table))
1208 return true;
1209
1210 /* Are there links available for every entry in table? */
1211 list_for_each_table_entry(entry, header) {
1212 const char *procname = entry->procname;
1213 link = find_entry(&tmp_head, dir, procname, strlen(procname));
1214 if (!link)
1215 return false;
1216 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1217 continue;
1218 if (S_ISLNK(link->mode) && (link->data == link_root))
1219 continue;
1220 return false;
1221 }
1222
1223 /* The checks passed. Increase the registration count on the links */
1224 list_for_each_table_entry(entry, header) {
1225 const char *procname = entry->procname;
1226 link = find_entry(&tmp_head, dir, procname, strlen(procname));
1227 tmp_head->nreg++;
1228 }
1229 return true;
1230}
1231
1232static int insert_links(struct ctl_table_header *head)
1233{
1234 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1235 struct ctl_dir *core_parent;
1236 struct ctl_table_header *links;
1237 int err;
1238
1239 if (head->set == root_set)
1240 return 0;
1241
1242 core_parent = xlate_dir(root_set, head->parent);
1243 if (IS_ERR(core_parent))
1244 return 0;
1245
1246 if (get_links(core_parent, head, head->root))
1247 return 0;
1248
1249 core_parent->header.nreg++;
1250 spin_unlock(&sysctl_lock);
1251
1252 links = new_links(core_parent, head);
1253
1254 spin_lock(&sysctl_lock);
1255 err = -ENOMEM;
1256 if (!links)
1257 goto out;
1258
1259 err = 0;
1260 if (get_links(core_parent, head, head->root)) {
1261 kfree(links);
1262 goto out;
1263 }
1264
1265 err = insert_header(core_parent, links);
1266 if (err)
1267 kfree(links);
1268out:
1269 drop_sysctl_table(&core_parent->header);
1270 return err;
1271}
1272
1273/* Find the directory for the ctl_table. If one is not found create it. */
1274static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)
1275{
1276 const char *name, *nextname;
1277
1278 for (name = path; name; name = nextname) {
1279 int namelen;
1280 nextname = strchr(name, '/');
1281 if (nextname) {
1282 namelen = nextname - name;
1283 nextname++;
1284 } else {
1285 namelen = strlen(name);
1286 }
1287 if (namelen == 0)
1288 continue;
1289
1290 /*
1291 * namelen ensures if name is "foo/bar/yay" only foo is
1292 * registered first. We traverse as if using mkdir -p and
1293 * return a ctl_dir for the last directory entry.
1294 */
1295 dir = get_subdir(dir, name, namelen);
1296 if (IS_ERR(dir))
1297 break;
1298 }
1299 return dir;
1300}
1301
1302/**
1303 * __register_sysctl_table - register a leaf sysctl table
1304 * @set: Sysctl tree to register on
1305 * @path: The path to the directory the sysctl table is in.
1306 * @table: the top-level table structure without any child. This table
1307 * should not be free'd after registration. So it should not be
1308 * used on stack. It can either be a global or dynamically allocated
1309 * by the caller and free'd later after sysctl unregistration.
1310 * @table_size : The number of elements in table
1311 *
1312 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1313 * array. A completely 0 filled entry terminates the table.
1314 *
1315 * The members of the &struct ctl_table structure are used as follows:
1316 *
1317 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1318 * enter a sysctl file
1319 *
1320 * data - a pointer to data for use by proc_handler
1321 *
1322 * maxlen - the maximum size in bytes of the data
1323 *
1324 * mode - the file permissions for the /proc/sys file
1325 *
1326 * child - must be %NULL.
1327 *
1328 * proc_handler - the text handler routine (described below)
1329 *
1330 * extra1, extra2 - extra pointers usable by the proc handler routines
1331 * XXX: we should eventually modify these to use long min / max [0]
1332 * [0] https://lkml.kernel.org/87zgpte9o4.fsf@email.froward.int.ebiederm.org
1333 *
1334 * Leaf nodes in the sysctl tree will be represented by a single file
1335 * under /proc; non-leaf nodes (where child is not NULL) are not allowed,
1336 * sysctl_check_table() verifies this.
1337 *
1338 * There must be a proc_handler routine for any terminal nodes.
1339 * Several default handlers are available to cover common cases -
1340 *
1341 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1342 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1343 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1344 *
1345 * It is the handler's job to read the input buffer from user memory
1346 * and process it. The handler should return 0 on success.
1347 *
1348 * This routine returns %NULL on a failure to register, and a pointer
1349 * to the table header on success.
1350 */
1351struct ctl_table_header *__register_sysctl_table(
1352 struct ctl_table_set *set,
1353 const char *path, struct ctl_table *table, size_t table_size)
1354{
1355 struct ctl_table_root *root = set->dir.header.root;
1356 struct ctl_table_header *header;
1357 struct ctl_dir *dir;
1358 struct ctl_node *node;
1359
1360 header = kzalloc(sizeof(struct ctl_table_header) +
1361 sizeof(struct ctl_node)*table_size, GFP_KERNEL_ACCOUNT);
1362 if (!header)
1363 return NULL;
1364
1365 node = (struct ctl_node *)(header + 1);
1366 init_header(header, root, set, node, table, table_size);
1367 if (sysctl_check_table(path, header))
1368 goto fail;
1369
1370 spin_lock(&sysctl_lock);
1371 dir = &set->dir;
1372 /* Reference moved down the directory tree get_subdir */
1373 dir->header.nreg++;
1374 spin_unlock(&sysctl_lock);
1375
1376 dir = sysctl_mkdir_p(dir, path);
1377 if (IS_ERR(dir))
1378 goto fail;
1379 spin_lock(&sysctl_lock);
1380 if (insert_header(dir, header))
1381 goto fail_put_dir_locked;
1382
1383 drop_sysctl_table(&dir->header);
1384 spin_unlock(&sysctl_lock);
1385
1386 return header;
1387
1388fail_put_dir_locked:
1389 drop_sysctl_table(&dir->header);
1390 spin_unlock(&sysctl_lock);
1391fail:
1392 kfree(header);
1393 return NULL;
1394}
1395
1396/**
1397 * register_sysctl_sz - register a sysctl table
1398 * @path: The path to the directory the sysctl table is in. If the path
1399 * doesn't exist we will create it for you.
1400 * @table: the table structure. The calller must ensure the life of the @table
1401 * will be kept during the lifetime use of the syctl. It must not be freed
1402 * until unregister_sysctl_table() is called with the given returned table
1403 * with this registration. If your code is non modular then you don't need
1404 * to call unregister_sysctl_table() and can instead use something like
1405 * register_sysctl_init() which does not care for the result of the syctl
1406 * registration.
1407 * @table_size: The number of elements in table.
1408 *
1409 * Register a sysctl table. @table should be a filled in ctl_table
1410 * array. A completely 0 filled entry terminates the table.
1411 *
1412 * See __register_sysctl_table for more details.
1413 */
1414struct ctl_table_header *register_sysctl_sz(const char *path, struct ctl_table *table,
1415 size_t table_size)
1416{
1417 return __register_sysctl_table(&sysctl_table_root.default_set,
1418 path, table, table_size);
1419}
1420EXPORT_SYMBOL(register_sysctl_sz);
1421
1422/**
1423 * __register_sysctl_init() - register sysctl table to path
1424 * @path: path name for sysctl base. If that path doesn't exist we will create
1425 * it for you.
1426 * @table: This is the sysctl table that needs to be registered to the path.
1427 * The caller must ensure the life of the @table will be kept during the
1428 * lifetime use of the sysctl.
1429 * @table_name: The name of sysctl table, only used for log printing when
1430 * registration fails
1431 * @table_size: The number of elements in table
1432 *
1433 * The sysctl interface is used by userspace to query or modify at runtime
1434 * a predefined value set on a variable. These variables however have default
1435 * values pre-set. Code which depends on these variables will always work even
1436 * if register_sysctl() fails. If register_sysctl() fails you'd just loose the
1437 * ability to query or modify the sysctls dynamically at run time. Chances of
1438 * register_sysctl() failing on init are extremely low, and so for both reasons
1439 * this function does not return any error as it is used by initialization code.
1440 *
1441 * Context: if your base directory does not exist it will be created for you.
1442 */
1443void __init __register_sysctl_init(const char *path, struct ctl_table *table,
1444 const char *table_name, size_t table_size)
1445{
1446 struct ctl_table_header *hdr = register_sysctl_sz(path, table, table_size);
1447
1448 if (unlikely(!hdr)) {
1449 pr_err("failed when register_sysctl_sz %s to %s\n", table_name, path);
1450 return;
1451 }
1452 kmemleak_not_leak(hdr);
1453}
1454
1455static void put_links(struct ctl_table_header *header)
1456{
1457 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1458 struct ctl_table_root *root = header->root;
1459 struct ctl_dir *parent = header->parent;
1460 struct ctl_dir *core_parent;
1461 struct ctl_table *entry;
1462
1463 if (header->set == root_set)
1464 return;
1465
1466 core_parent = xlate_dir(root_set, parent);
1467 if (IS_ERR(core_parent))
1468 return;
1469
1470 list_for_each_table_entry(entry, header) {
1471 struct ctl_table_header *link_head;
1472 struct ctl_table *link;
1473 const char *name = entry->procname;
1474
1475 link = find_entry(&link_head, core_parent, name, strlen(name));
1476 if (link &&
1477 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1478 (S_ISLNK(link->mode) && (link->data == root)))) {
1479 drop_sysctl_table(link_head);
1480 }
1481 else {
1482 pr_err("sysctl link missing during unregister: ");
1483 sysctl_print_dir(parent);
1484 pr_cont("%s\n", name);
1485 }
1486 }
1487}
1488
1489static void drop_sysctl_table(struct ctl_table_header *header)
1490{
1491 struct ctl_dir *parent = header->parent;
1492
1493 if (--header->nreg)
1494 return;
1495
1496 if (parent) {
1497 put_links(header);
1498 start_unregistering(header);
1499 }
1500
1501 if (!--header->count)
1502 kfree_rcu(header, rcu);
1503
1504 if (parent)
1505 drop_sysctl_table(&parent->header);
1506}
1507
1508/**
1509 * unregister_sysctl_table - unregister a sysctl table hierarchy
1510 * @header: the header returned from register_sysctl or __register_sysctl_table
1511 *
1512 * Unregisters the sysctl table and all children. proc entries may not
1513 * actually be removed until they are no longer used by anyone.
1514 */
1515void unregister_sysctl_table(struct ctl_table_header * header)
1516{
1517 might_sleep();
1518
1519 if (header == NULL)
1520 return;
1521
1522 spin_lock(&sysctl_lock);
1523 drop_sysctl_table(header);
1524 spin_unlock(&sysctl_lock);
1525}
1526EXPORT_SYMBOL(unregister_sysctl_table);
1527
1528void setup_sysctl_set(struct ctl_table_set *set,
1529 struct ctl_table_root *root,
1530 int (*is_seen)(struct ctl_table_set *))
1531{
1532 memset(set, 0, sizeof(*set));
1533 set->is_seen = is_seen;
1534 init_header(&set->dir.header, root, set, NULL, root_table, 1);
1535}
1536
1537void retire_sysctl_set(struct ctl_table_set *set)
1538{
1539 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1540}
1541
1542int __init proc_sys_init(void)
1543{
1544 struct proc_dir_entry *proc_sys_root;
1545
1546 proc_sys_root = proc_mkdir("sys", NULL);
1547 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1548 proc_sys_root->proc_dir_ops = &proc_sys_dir_file_operations;
1549 proc_sys_root->nlink = 0;
1550
1551 return sysctl_init_bases();
1552}
1553
1554struct sysctl_alias {
1555 const char *kernel_param;
1556 const char *sysctl_param;
1557};
1558
1559/*
1560 * Historically some settings had both sysctl and a command line parameter.
1561 * With the generic sysctl. parameter support, we can handle them at a single
1562 * place and only keep the historical name for compatibility. This is not meant
1563 * to add brand new aliases. When adding existing aliases, consider whether
1564 * the possibly different moment of changing the value (e.g. from early_param
1565 * to the moment do_sysctl_args() is called) is an issue for the specific
1566 * parameter.
1567 */
1568static const struct sysctl_alias sysctl_aliases[] = {
1569 {"hardlockup_all_cpu_backtrace", "kernel.hardlockup_all_cpu_backtrace" },
1570 {"hung_task_panic", "kernel.hung_task_panic" },
1571 {"numa_zonelist_order", "vm.numa_zonelist_order" },
1572 {"softlockup_all_cpu_backtrace", "kernel.softlockup_all_cpu_backtrace" },
1573 { }
1574};
1575
1576static const char *sysctl_find_alias(char *param)
1577{
1578 const struct sysctl_alias *alias;
1579
1580 for (alias = &sysctl_aliases[0]; alias->kernel_param != NULL; alias++) {
1581 if (strcmp(alias->kernel_param, param) == 0)
1582 return alias->sysctl_param;
1583 }
1584
1585 return NULL;
1586}
1587
1588bool sysctl_is_alias(char *param)
1589{
1590 const char *alias = sysctl_find_alias(param);
1591
1592 return alias != NULL;
1593}
1594
1595/* Set sysctl value passed on kernel command line. */
1596static int process_sysctl_arg(char *param, char *val,
1597 const char *unused, void *arg)
1598{
1599 char *path;
1600 struct vfsmount **proc_mnt = arg;
1601 struct file_system_type *proc_fs_type;
1602 struct file *file;
1603 int len;
1604 int err;
1605 loff_t pos = 0;
1606 ssize_t wret;
1607
1608 if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {
1609 param += sizeof("sysctl") - 1;
1610
1611 if (param[0] != '/' && param[0] != '.')
1612 return 0;
1613
1614 param++;
1615 } else {
1616 param = (char *) sysctl_find_alias(param);
1617 if (!param)
1618 return 0;
1619 }
1620
1621 if (!val)
1622 return -EINVAL;
1623 len = strlen(val);
1624 if (len == 0)
1625 return -EINVAL;
1626
1627 /*
1628 * To set sysctl options, we use a temporary mount of proc, look up the
1629 * respective sys/ file and write to it. To avoid mounting it when no
1630 * options were given, we mount it only when the first sysctl option is
1631 * found. Why not a persistent mount? There are problems with a
1632 * persistent mount of proc in that it forces userspace not to use any
1633 * proc mount options.
1634 */
1635 if (!*proc_mnt) {
1636 proc_fs_type = get_fs_type("proc");
1637 if (!proc_fs_type) {
1638 pr_err("Failed to find procfs to set sysctl from command line\n");
1639 return 0;
1640 }
1641 *proc_mnt = kern_mount(proc_fs_type);
1642 put_filesystem(proc_fs_type);
1643 if (IS_ERR(*proc_mnt)) {
1644 pr_err("Failed to mount procfs to set sysctl from command line\n");
1645 return 0;
1646 }
1647 }
1648
1649 path = kasprintf(GFP_KERNEL, "sys/%s", param);
1650 if (!path)
1651 panic("%s: Failed to allocate path for %s\n", __func__, param);
1652 strreplace(path, '.', '/');
1653
1654 file = file_open_root_mnt(*proc_mnt, path, O_WRONLY, 0);
1655 if (IS_ERR(file)) {
1656 err = PTR_ERR(file);
1657 if (err == -ENOENT)
1658 pr_err("Failed to set sysctl parameter '%s=%s': parameter not found\n",
1659 param, val);
1660 else if (err == -EACCES)
1661 pr_err("Failed to set sysctl parameter '%s=%s': permission denied (read-only?)\n",
1662 param, val);
1663 else
1664 pr_err("Error %pe opening proc file to set sysctl parameter '%s=%s'\n",
1665 file, param, val);
1666 goto out;
1667 }
1668 wret = kernel_write(file, val, len, &pos);
1669 if (wret < 0) {
1670 err = wret;
1671 if (err == -EINVAL)
1672 pr_err("Failed to set sysctl parameter '%s=%s': invalid value\n",
1673 param, val);
1674 else
1675 pr_err("Error %pe writing to proc file to set sysctl parameter '%s=%s'\n",
1676 ERR_PTR(err), param, val);
1677 } else if (wret != len) {
1678 pr_err("Wrote only %zd bytes of %d writing to proc file %s to set sysctl parameter '%s=%s\n",
1679 wret, len, path, param, val);
1680 }
1681
1682 err = filp_close(file, NULL);
1683 if (err)
1684 pr_err("Error %pe closing proc file to set sysctl parameter '%s=%s\n",
1685 ERR_PTR(err), param, val);
1686out:
1687 kfree(path);
1688 return 0;
1689}
1690
1691void do_sysctl_args(void)
1692{
1693 char *command_line;
1694 struct vfsmount *proc_mnt = NULL;
1695
1696 command_line = kstrdup(saved_command_line, GFP_KERNEL);
1697 if (!command_line)
1698 panic("%s: Failed to allocate copy of command line\n", __func__);
1699
1700 parse_args("Setting sysctl args", command_line,
1701 NULL, 0, -1, -1, &proc_mnt, process_sysctl_arg);
1702
1703 if (proc_mnt)
1704 kern_unmount(proc_mnt);
1705
1706 kfree(command_line);
1707}
1/*
2 * /proc/sys support
3 */
4#include <linux/init.h>
5#include <linux/sysctl.h>
6#include <linux/poll.h>
7#include <linux/proc_fs.h>
8#include <linux/printk.h>
9#include <linux/security.h>
10#include <linux/sched.h>
11#include <linux/namei.h>
12#include <linux/mm.h>
13#include <linux/module.h>
14#include "internal.h"
15
16static const struct dentry_operations proc_sys_dentry_operations;
17static const struct file_operations proc_sys_file_operations;
18static const struct inode_operations proc_sys_inode_operations;
19static const struct file_operations proc_sys_dir_file_operations;
20static const struct inode_operations proc_sys_dir_operations;
21
22void proc_sys_poll_notify(struct ctl_table_poll *poll)
23{
24 if (!poll)
25 return;
26
27 atomic_inc(&poll->event);
28 wake_up_interruptible(&poll->wait);
29}
30
31static struct ctl_table root_table[] = {
32 {
33 .procname = "",
34 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
35 },
36 { }
37};
38static struct ctl_table_root sysctl_table_root = {
39 .default_set.dir.header = {
40 {{.count = 1,
41 .nreg = 1,
42 .ctl_table = root_table }},
43 .ctl_table_arg = root_table,
44 .root = &sysctl_table_root,
45 .set = &sysctl_table_root.default_set,
46 },
47};
48
49static DEFINE_SPINLOCK(sysctl_lock);
50
51static void drop_sysctl_table(struct ctl_table_header *header);
52static int sysctl_follow_link(struct ctl_table_header **phead,
53 struct ctl_table **pentry, struct nsproxy *namespaces);
54static int insert_links(struct ctl_table_header *head);
55static void put_links(struct ctl_table_header *header);
56
57static void sysctl_print_dir(struct ctl_dir *dir)
58{
59 if (dir->header.parent)
60 sysctl_print_dir(dir->header.parent);
61 pr_cont("%s/", dir->header.ctl_table[0].procname);
62}
63
64static int namecmp(const char *name1, int len1, const char *name2, int len2)
65{
66 int minlen;
67 int cmp;
68
69 minlen = len1;
70 if (minlen > len2)
71 minlen = len2;
72
73 cmp = memcmp(name1, name2, minlen);
74 if (cmp == 0)
75 cmp = len1 - len2;
76 return cmp;
77}
78
79/* Called under sysctl_lock */
80static struct ctl_table *find_entry(struct ctl_table_header **phead,
81 struct ctl_dir *dir, const char *name, int namelen)
82{
83 struct ctl_table_header *head;
84 struct ctl_table *entry;
85 struct rb_node *node = dir->root.rb_node;
86
87 while (node)
88 {
89 struct ctl_node *ctl_node;
90 const char *procname;
91 int cmp;
92
93 ctl_node = rb_entry(node, struct ctl_node, node);
94 head = ctl_node->header;
95 entry = &head->ctl_table[ctl_node - head->node];
96 procname = entry->procname;
97
98 cmp = namecmp(name, namelen, procname, strlen(procname));
99 if (cmp < 0)
100 node = node->rb_left;
101 else if (cmp > 0)
102 node = node->rb_right;
103 else {
104 *phead = head;
105 return entry;
106 }
107 }
108 return NULL;
109}
110
111static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
112{
113 struct rb_node *node = &head->node[entry - head->ctl_table].node;
114 struct rb_node **p = &head->parent->root.rb_node;
115 struct rb_node *parent = NULL;
116 const char *name = entry->procname;
117 int namelen = strlen(name);
118
119 while (*p) {
120 struct ctl_table_header *parent_head;
121 struct ctl_table *parent_entry;
122 struct ctl_node *parent_node;
123 const char *parent_name;
124 int cmp;
125
126 parent = *p;
127 parent_node = rb_entry(parent, struct ctl_node, node);
128 parent_head = parent_node->header;
129 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
130 parent_name = parent_entry->procname;
131
132 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
133 if (cmp < 0)
134 p = &(*p)->rb_left;
135 else if (cmp > 0)
136 p = &(*p)->rb_right;
137 else {
138 pr_err("sysctl duplicate entry: ");
139 sysctl_print_dir(head->parent);
140 pr_cont("/%s\n", entry->procname);
141 return -EEXIST;
142 }
143 }
144
145 rb_link_node(node, parent, p);
146 rb_insert_color(node, &head->parent->root);
147 return 0;
148}
149
150static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
151{
152 struct rb_node *node = &head->node[entry - head->ctl_table].node;
153
154 rb_erase(node, &head->parent->root);
155}
156
157static void init_header(struct ctl_table_header *head,
158 struct ctl_table_root *root, struct ctl_table_set *set,
159 struct ctl_node *node, struct ctl_table *table)
160{
161 head->ctl_table = table;
162 head->ctl_table_arg = table;
163 head->used = 0;
164 head->count = 1;
165 head->nreg = 1;
166 head->unregistering = NULL;
167 head->root = root;
168 head->set = set;
169 head->parent = NULL;
170 head->node = node;
171 if (node) {
172 struct ctl_table *entry;
173 for (entry = table; entry->procname; entry++, node++)
174 node->header = head;
175 }
176}
177
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 BUG_ON(!head);
270 spin_lock(&sysctl_lock);
271 if (!use_table(head))
272 head = ERR_PTR(-ENOENT);
273 spin_unlock(&sysctl_lock);
274 return head;
275}
276
277static void sysctl_head_finish(struct ctl_table_header *head)
278{
279 if (!head)
280 return;
281 spin_lock(&sysctl_lock);
282 unuse_table(head);
283 spin_unlock(&sysctl_lock);
284}
285
286static struct ctl_table_set *
287lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces)
288{
289 struct ctl_table_set *set = &root->default_set;
290 if (root->lookup)
291 set = root->lookup(root, namespaces);
292 return set;
293}
294
295static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
296 struct ctl_dir *dir,
297 const char *name, int namelen)
298{
299 struct ctl_table_header *head;
300 struct ctl_table *entry;
301
302 spin_lock(&sysctl_lock);
303 entry = find_entry(&head, dir, name, namelen);
304 if (entry && use_table(head))
305 *phead = head;
306 else
307 entry = NULL;
308 spin_unlock(&sysctl_lock);
309 return entry;
310}
311
312static struct ctl_node *first_usable_entry(struct rb_node *node)
313{
314 struct ctl_node *ctl_node;
315
316 for (;node; node = rb_next(node)) {
317 ctl_node = rb_entry(node, struct ctl_node, node);
318 if (use_table(ctl_node->header))
319 return ctl_node;
320 }
321 return NULL;
322}
323
324static void first_entry(struct ctl_dir *dir,
325 struct ctl_table_header **phead, struct ctl_table **pentry)
326{
327 struct ctl_table_header *head = NULL;
328 struct ctl_table *entry = NULL;
329 struct ctl_node *ctl_node;
330
331 spin_lock(&sysctl_lock);
332 ctl_node = first_usable_entry(rb_first(&dir->root));
333 spin_unlock(&sysctl_lock);
334 if (ctl_node) {
335 head = ctl_node->header;
336 entry = &head->ctl_table[ctl_node - head->node];
337 }
338 *phead = head;
339 *pentry = entry;
340}
341
342static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
343{
344 struct ctl_table_header *head = *phead;
345 struct ctl_table *entry = *pentry;
346 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
347
348 spin_lock(&sysctl_lock);
349 unuse_table(head);
350
351 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
352 spin_unlock(&sysctl_lock);
353 head = NULL;
354 if (ctl_node) {
355 head = ctl_node->header;
356 entry = &head->ctl_table[ctl_node - head->node];
357 }
358 *phead = head;
359 *pentry = entry;
360}
361
362void register_sysctl_root(struct ctl_table_root *root)
363{
364}
365
366/*
367 * sysctl_perm does NOT grant the superuser all rights automatically, because
368 * some sysctl variables are readonly even to root.
369 */
370
371static int test_perm(int mode, int op)
372{
373 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
374 mode >>= 6;
375 else if (in_egroup_p(GLOBAL_ROOT_GID))
376 mode >>= 3;
377 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
378 return 0;
379 return -EACCES;
380}
381
382static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
383{
384 struct ctl_table_root *root = head->root;
385 int mode;
386
387 if (root->permissions)
388 mode = root->permissions(head, table);
389 else
390 mode = table->mode;
391
392 return test_perm(mode, op);
393}
394
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 unsigned int flags)
437{
438 struct ctl_table_header *head = grab_header(dir);
439 struct ctl_table_header *h = NULL;
440 struct qstr *name = &dentry->d_name;
441 struct ctl_table *p;
442 struct inode *inode;
443 struct dentry *err = ERR_PTR(-ENOENT);
444 struct ctl_dir *ctl_dir;
445 int ret;
446
447 if (IS_ERR(head))
448 return ERR_CAST(head);
449
450 ctl_dir = container_of(head, struct ctl_dir, header);
451
452 p = lookup_entry(&h, ctl_dir, name->name, name->len);
453 if (!p)
454 goto out;
455
456 if (S_ISLNK(p->mode)) {
457 ret = sysctl_follow_link(&h, &p, current->nsproxy);
458 err = ERR_PTR(ret);
459 if (ret)
460 goto out;
461 }
462
463 err = ERR_PTR(-ENOMEM);
464 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
465 if (!inode)
466 goto out;
467
468 err = NULL;
469 d_set_d_op(dentry, &proc_sys_dentry_operations);
470 d_add(dentry, inode);
471
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 = file_inode(filp);
483 struct ctl_table_header *head = grab_header(inode);
484 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
485 ssize_t error;
486 size_t res;
487
488 if (IS_ERR(head))
489 return PTR_ERR(head);
490
491 /*
492 * At this point we know that the sysctl was not unregistered
493 * and won't be until we finish.
494 */
495 error = -EPERM;
496 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
497 goto out;
498
499 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
500 error = -EINVAL;
501 if (!table->proc_handler)
502 goto out;
503
504 /* careful: calling conventions are nasty here */
505 res = count;
506 error = table->proc_handler(table, write, buf, &res, ppos);
507 if (!error)
508 error = res;
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 = file_inode(filp);
547 struct ctl_table_header *head = grab_header(inode);
548 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
549 unsigned int ret = DEFAULT_POLLMASK;
550 unsigned long event;
551
552 /* sysctl was unregistered */
553 if (IS_ERR(head))
554 return POLLERR | POLLHUP;
555
556 if (!table->proc_handler)
557 goto out;
558
559 if (!table->poll)
560 goto out;
561
562 event = (unsigned long)filp->private_data;
563 poll_wait(filp, &table->poll->wait, wait);
564
565 if (event != atomic_read(&table->poll->event)) {
566 filp->private_data = proc_sys_poll_event(table->poll);
567 ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI;
568 }
569
570out:
571 sysctl_head_finish(head);
572
573 return ret;
574}
575
576static bool proc_sys_fill_cache(struct file *file,
577 struct dir_context *ctx,
578 struct ctl_table_header *head,
579 struct ctl_table *table)
580{
581 struct dentry *child, *dir = file->f_path.dentry;
582 struct inode *inode;
583 struct qstr qname;
584 ino_t ino = 0;
585 unsigned type = DT_UNKNOWN;
586
587 qname.name = table->procname;
588 qname.len = strlen(table->procname);
589 qname.hash = full_name_hash(qname.name, qname.len);
590
591 child = d_lookup(dir, &qname);
592 if (!child) {
593 child = d_alloc(dir, &qname);
594 if (child) {
595 inode = proc_sys_make_inode(dir->d_sb, head, table);
596 if (!inode) {
597 dput(child);
598 return false;
599 } else {
600 d_set_d_op(child, &proc_sys_dentry_operations);
601 d_add(child, inode);
602 }
603 } else {
604 return false;
605 }
606 }
607 inode = child->d_inode;
608 ino = inode->i_ino;
609 type = inode->i_mode >> 12;
610 dput(child);
611 return dir_emit(ctx, qname.name, qname.len, ino, type);
612}
613
614static bool proc_sys_link_fill_cache(struct file *file,
615 struct dir_context *ctx,
616 struct ctl_table_header *head,
617 struct ctl_table *table)
618{
619 bool ret = true;
620 head = sysctl_head_grab(head);
621
622 if (S_ISLNK(table->mode)) {
623 /* It is not an error if we can not follow the link ignore it */
624 int err = sysctl_follow_link(&head, &table, current->nsproxy);
625 if (err)
626 goto out;
627 }
628
629 ret = proc_sys_fill_cache(file, ctx, head, table);
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 struct dir_context *ctx)
638{
639 bool res;
640
641 if ((*pos)++ < ctx->pos)
642 return true;
643
644 if (unlikely(S_ISLNK(table->mode)))
645 res = proc_sys_link_fill_cache(file, ctx, head, table);
646 else
647 res = proc_sys_fill_cache(file, ctx, head, table);
648
649 if (res)
650 ctx->pos = *pos;
651
652 return res;
653}
654
655static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
656{
657 struct ctl_table_header *head = grab_header(file_inode(file));
658 struct ctl_table_header *h = NULL;
659 struct ctl_table *entry;
660 struct ctl_dir *ctl_dir;
661 unsigned long pos;
662
663 if (IS_ERR(head))
664 return PTR_ERR(head);
665
666 ctl_dir = container_of(head, struct ctl_dir, header);
667
668 if (!dir_emit_dots(file, ctx))
669 return 0;
670
671 pos = 2;
672
673 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
674 if (!scan(h, entry, &pos, file, ctx)) {
675 sysctl_head_finish(h);
676 break;
677 }
678 }
679 sysctl_head_finish(head);
680 return 0;
681}
682
683static int proc_sys_permission(struct inode *inode, int mask)
684{
685 /*
686 * sysctl entries that are not writeable,
687 * are _NOT_ writeable, capabilities or not.
688 */
689 struct ctl_table_header *head;
690 struct ctl_table *table;
691 int error;
692
693 /* Executable files are not allowed under /proc/sys/ */
694 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
695 return -EACCES;
696
697 head = grab_header(inode);
698 if (IS_ERR(head))
699 return PTR_ERR(head);
700
701 table = PROC_I(inode)->sysctl_entry;
702 if (!table) /* global root - r-xr-xr-x */
703 error = mask & MAY_WRITE ? -EACCES : 0;
704 else /* Use the permissions on the sysctl table entry */
705 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
706
707 sysctl_head_finish(head);
708 return error;
709}
710
711static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
712{
713 struct inode *inode = dentry->d_inode;
714 int error;
715
716 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
717 return -EPERM;
718
719 error = inode_change_ok(inode, attr);
720 if (error)
721 return error;
722
723 setattr_copy(inode, attr);
724 mark_inode_dirty(inode);
725 return 0;
726}
727
728static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
729{
730 struct inode *inode = dentry->d_inode;
731 struct ctl_table_header *head = grab_header(inode);
732 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
733
734 if (IS_ERR(head))
735 return PTR_ERR(head);
736
737 generic_fillattr(inode, stat);
738 if (table)
739 stat->mode = (stat->mode & S_IFMT) | table->mode;
740
741 sysctl_head_finish(head);
742 return 0;
743}
744
745static const struct file_operations proc_sys_file_operations = {
746 .open = proc_sys_open,
747 .poll = proc_sys_poll,
748 .read = proc_sys_read,
749 .write = proc_sys_write,
750 .llseek = default_llseek,
751};
752
753static const struct file_operations proc_sys_dir_file_operations = {
754 .read = generic_read_dir,
755 .iterate = proc_sys_readdir,
756 .llseek = generic_file_llseek,
757};
758
759static const struct inode_operations proc_sys_inode_operations = {
760 .permission = proc_sys_permission,
761 .setattr = proc_sys_setattr,
762 .getattr = proc_sys_getattr,
763};
764
765static const struct inode_operations proc_sys_dir_operations = {
766 .lookup = proc_sys_lookup,
767 .permission = proc_sys_permission,
768 .setattr = proc_sys_setattr,
769 .getattr = proc_sys_getattr,
770};
771
772static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
773{
774 if (flags & LOOKUP_RCU)
775 return -ECHILD;
776 return !PROC_I(dentry->d_inode)->sysctl->unregistering;
777}
778
779static int proc_sys_delete(const struct dentry *dentry)
780{
781 return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
782}
783
784static int sysctl_is_seen(struct ctl_table_header *p)
785{
786 struct ctl_table_set *set = p->set;
787 int res;
788 spin_lock(&sysctl_lock);
789 if (p->unregistering)
790 res = 0;
791 else if (!set->is_seen)
792 res = 1;
793 else
794 res = set->is_seen(set);
795 spin_unlock(&sysctl_lock);
796 return res;
797}
798
799static int proc_sys_compare(const struct dentry *parent, const struct dentry *dentry,
800 unsigned int len, const char *str, const struct qstr *name)
801{
802 struct ctl_table_header *head;
803 struct inode *inode;
804
805 /* Although proc doesn't have negative dentries, rcu-walk means
806 * that inode here can be NULL */
807 /* AV: can it, indeed? */
808 inode = ACCESS_ONCE(dentry->d_inode);
809 if (!inode)
810 return 1;
811 if (name->len != len)
812 return 1;
813 if (memcmp(name->name, str, len))
814 return 1;
815 head = rcu_dereference(PROC_I(inode)->sysctl);
816 return !head || !sysctl_is_seen(head);
817}
818
819static const struct dentry_operations proc_sys_dentry_operations = {
820 .d_revalidate = proc_sys_revalidate,
821 .d_delete = proc_sys_delete,
822 .d_compare = proc_sys_compare,
823};
824
825static struct ctl_dir *find_subdir(struct ctl_dir *dir,
826 const char *name, int namelen)
827{
828 struct ctl_table_header *head;
829 struct ctl_table *entry;
830
831 entry = find_entry(&head, dir, name, namelen);
832 if (!entry)
833 return ERR_PTR(-ENOENT);
834 if (!S_ISDIR(entry->mode))
835 return ERR_PTR(-ENOTDIR);
836 return container_of(head, struct ctl_dir, header);
837}
838
839static struct ctl_dir *new_dir(struct ctl_table_set *set,
840 const char *name, int namelen)
841{
842 struct ctl_table *table;
843 struct ctl_dir *new;
844 struct ctl_node *node;
845 char *new_name;
846
847 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
848 sizeof(struct ctl_table)*2 + namelen + 1,
849 GFP_KERNEL);
850 if (!new)
851 return NULL;
852
853 node = (struct ctl_node *)(new + 1);
854 table = (struct ctl_table *)(node + 1);
855 new_name = (char *)(table + 2);
856 memcpy(new_name, name, namelen);
857 new_name[namelen] = '\0';
858 table[0].procname = new_name;
859 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
860 init_header(&new->header, set->dir.header.root, set, node, table);
861
862 return new;
863}
864
865/**
866 * get_subdir - find or create a subdir with the specified name.
867 * @dir: Directory to create the subdirectory in
868 * @name: The name of the subdirectory to find or create
869 * @namelen: The length of name
870 *
871 * Takes a directory with an elevated reference count so we know that
872 * if we drop the lock the directory will not go away. Upon success
873 * the reference is moved from @dir to the returned subdirectory.
874 * Upon error an error code is returned and the reference on @dir is
875 * simply dropped.
876 */
877static struct ctl_dir *get_subdir(struct ctl_dir *dir,
878 const char *name, int namelen)
879{
880 struct ctl_table_set *set = dir->header.set;
881 struct ctl_dir *subdir, *new = NULL;
882 int err;
883
884 spin_lock(&sysctl_lock);
885 subdir = find_subdir(dir, name, namelen);
886 if (!IS_ERR(subdir))
887 goto found;
888 if (PTR_ERR(subdir) != -ENOENT)
889 goto failed;
890
891 spin_unlock(&sysctl_lock);
892 new = new_dir(set, name, namelen);
893 spin_lock(&sysctl_lock);
894 subdir = ERR_PTR(-ENOMEM);
895 if (!new)
896 goto failed;
897
898 /* Was the subdir added while we dropped the lock? */
899 subdir = find_subdir(dir, name, namelen);
900 if (!IS_ERR(subdir))
901 goto found;
902 if (PTR_ERR(subdir) != -ENOENT)
903 goto failed;
904
905 /* Nope. Use the our freshly made directory entry. */
906 err = insert_header(dir, &new->header);
907 subdir = ERR_PTR(err);
908 if (err)
909 goto failed;
910 subdir = new;
911found:
912 subdir->header.nreg++;
913failed:
914 if (unlikely(IS_ERR(subdir))) {
915 pr_err("sysctl could not get directory: ");
916 sysctl_print_dir(dir);
917 pr_cont("/%*.*s %ld\n",
918 namelen, namelen, name, PTR_ERR(subdir));
919 }
920 drop_sysctl_table(&dir->header);
921 if (new)
922 drop_sysctl_table(&new->header);
923 spin_unlock(&sysctl_lock);
924 return subdir;
925}
926
927static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
928{
929 struct ctl_dir *parent;
930 const char *procname;
931 if (!dir->header.parent)
932 return &set->dir;
933 parent = xlate_dir(set, dir->header.parent);
934 if (IS_ERR(parent))
935 return parent;
936 procname = dir->header.ctl_table[0].procname;
937 return find_subdir(parent, procname, strlen(procname));
938}
939
940static int sysctl_follow_link(struct ctl_table_header **phead,
941 struct ctl_table **pentry, struct nsproxy *namespaces)
942{
943 struct ctl_table_header *head;
944 struct ctl_table_root *root;
945 struct ctl_table_set *set;
946 struct ctl_table *entry;
947 struct ctl_dir *dir;
948 int ret;
949
950 ret = 0;
951 spin_lock(&sysctl_lock);
952 root = (*pentry)->data;
953 set = lookup_header_set(root, namespaces);
954 dir = xlate_dir(set, (*phead)->parent);
955 if (IS_ERR(dir))
956 ret = PTR_ERR(dir);
957 else {
958 const char *procname = (*pentry)->procname;
959 head = NULL;
960 entry = find_entry(&head, dir, procname, strlen(procname));
961 ret = -ENOENT;
962 if (entry && use_table(head)) {
963 unuse_table(*phead);
964 *phead = head;
965 *pentry = entry;
966 ret = 0;
967 }
968 }
969
970 spin_unlock(&sysctl_lock);
971 return ret;
972}
973
974static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
975{
976 struct va_format vaf;
977 va_list args;
978
979 va_start(args, fmt);
980 vaf.fmt = fmt;
981 vaf.va = &args;
982
983 pr_err("sysctl table check failed: %s/%s %pV\n",
984 path, table->procname, &vaf);
985
986 va_end(args);
987 return -EINVAL;
988}
989
990static int sysctl_check_table(const char *path, struct ctl_table *table)
991{
992 int err = 0;
993 for (; table->procname; table++) {
994 if (table->child)
995 err = sysctl_err(path, table, "Not a file");
996
997 if ((table->proc_handler == proc_dostring) ||
998 (table->proc_handler == proc_dointvec) ||
999 (table->proc_handler == proc_dointvec_minmax) ||
1000 (table->proc_handler == proc_dointvec_jiffies) ||
1001 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1002 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1003 (table->proc_handler == proc_doulongvec_minmax) ||
1004 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1005 if (!table->data)
1006 err = sysctl_err(path, table, "No data");
1007 if (!table->maxlen)
1008 err = sysctl_err(path, table, "No maxlen");
1009 }
1010 if (!table->proc_handler)
1011 err = sysctl_err(path, table, "No proc_handler");
1012
1013 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1014 err = sysctl_err(path, table, "bogus .mode 0%o",
1015 table->mode);
1016 }
1017 return err;
1018}
1019
1020static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1021 struct ctl_table_root *link_root)
1022{
1023 struct ctl_table *link_table, *entry, *link;
1024 struct ctl_table_header *links;
1025 struct ctl_node *node;
1026 char *link_name;
1027 int nr_entries, name_bytes;
1028
1029 name_bytes = 0;
1030 nr_entries = 0;
1031 for (entry = table; entry->procname; entry++) {
1032 nr_entries++;
1033 name_bytes += strlen(entry->procname) + 1;
1034 }
1035
1036 links = kzalloc(sizeof(struct ctl_table_header) +
1037 sizeof(struct ctl_node)*nr_entries +
1038 sizeof(struct ctl_table)*(nr_entries + 1) +
1039 name_bytes,
1040 GFP_KERNEL);
1041
1042 if (!links)
1043 return NULL;
1044
1045 node = (struct ctl_node *)(links + 1);
1046 link_table = (struct ctl_table *)(node + nr_entries);
1047 link_name = (char *)&link_table[nr_entries + 1];
1048
1049 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1050 int len = strlen(entry->procname) + 1;
1051 memcpy(link_name, entry->procname, len);
1052 link->procname = link_name;
1053 link->mode = S_IFLNK|S_IRWXUGO;
1054 link->data = link_root;
1055 link_name += len;
1056 }
1057 init_header(links, dir->header.root, dir->header.set, node, link_table);
1058 links->nreg = nr_entries;
1059
1060 return links;
1061}
1062
1063static bool get_links(struct ctl_dir *dir,
1064 struct ctl_table *table, struct ctl_table_root *link_root)
1065{
1066 struct ctl_table_header *head;
1067 struct ctl_table *entry, *link;
1068
1069 /* Are there links available for every entry in table? */
1070 for (entry = table; entry->procname; entry++) {
1071 const char *procname = entry->procname;
1072 link = find_entry(&head, dir, procname, strlen(procname));
1073 if (!link)
1074 return false;
1075 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1076 continue;
1077 if (S_ISLNK(link->mode) && (link->data == link_root))
1078 continue;
1079 return false;
1080 }
1081
1082 /* The checks passed. Increase the registration count on the links */
1083 for (entry = table; entry->procname; entry++) {
1084 const char *procname = entry->procname;
1085 link = find_entry(&head, dir, procname, strlen(procname));
1086 head->nreg++;
1087 }
1088 return true;
1089}
1090
1091static int insert_links(struct ctl_table_header *head)
1092{
1093 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1094 struct ctl_dir *core_parent = NULL;
1095 struct ctl_table_header *links;
1096 int err;
1097
1098 if (head->set == root_set)
1099 return 0;
1100
1101 core_parent = xlate_dir(root_set, head->parent);
1102 if (IS_ERR(core_parent))
1103 return 0;
1104
1105 if (get_links(core_parent, head->ctl_table, head->root))
1106 return 0;
1107
1108 core_parent->header.nreg++;
1109 spin_unlock(&sysctl_lock);
1110
1111 links = new_links(core_parent, head->ctl_table, head->root);
1112
1113 spin_lock(&sysctl_lock);
1114 err = -ENOMEM;
1115 if (!links)
1116 goto out;
1117
1118 err = 0;
1119 if (get_links(core_parent, head->ctl_table, head->root)) {
1120 kfree(links);
1121 goto out;
1122 }
1123
1124 err = insert_header(core_parent, links);
1125 if (err)
1126 kfree(links);
1127out:
1128 drop_sysctl_table(&core_parent->header);
1129 return err;
1130}
1131
1132/**
1133 * __register_sysctl_table - register a leaf sysctl table
1134 * @set: Sysctl tree to register on
1135 * @path: The path to the directory the sysctl table is in.
1136 * @table: the top-level table structure
1137 *
1138 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1139 * array. A completely 0 filled entry terminates the table.
1140 *
1141 * The members of the &struct ctl_table structure are used as follows:
1142 *
1143 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1144 * enter a sysctl file
1145 *
1146 * data - a pointer to data for use by proc_handler
1147 *
1148 * maxlen - the maximum size in bytes of the data
1149 *
1150 * mode - the file permissions for the /proc/sys file
1151 *
1152 * child - must be %NULL.
1153 *
1154 * proc_handler - the text handler routine (described below)
1155 *
1156 * extra1, extra2 - extra pointers usable by the proc handler routines
1157 *
1158 * Leaf nodes in the sysctl tree will be represented by a single file
1159 * under /proc; non-leaf nodes will be represented by directories.
1160 *
1161 * There must be a proc_handler routine for any terminal nodes.
1162 * Several default handlers are available to cover common cases -
1163 *
1164 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1165 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1166 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1167 *
1168 * It is the handler's job to read the input buffer from user memory
1169 * and process it. The handler should return 0 on success.
1170 *
1171 * This routine returns %NULL on a failure to register, and a pointer
1172 * to the table header on success.
1173 */
1174struct ctl_table_header *__register_sysctl_table(
1175 struct ctl_table_set *set,
1176 const char *path, struct ctl_table *table)
1177{
1178 struct ctl_table_root *root = set->dir.header.root;
1179 struct ctl_table_header *header;
1180 const char *name, *nextname;
1181 struct ctl_dir *dir;
1182 struct ctl_table *entry;
1183 struct ctl_node *node;
1184 int nr_entries = 0;
1185
1186 for (entry = table; entry->procname; entry++)
1187 nr_entries++;
1188
1189 header = kzalloc(sizeof(struct ctl_table_header) +
1190 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1191 if (!header)
1192 return NULL;
1193
1194 node = (struct ctl_node *)(header + 1);
1195 init_header(header, root, set, node, table);
1196 if (sysctl_check_table(path, table))
1197 goto fail;
1198
1199 spin_lock(&sysctl_lock);
1200 dir = &set->dir;
1201 /* Reference moved down the diretory tree get_subdir */
1202 dir->header.nreg++;
1203 spin_unlock(&sysctl_lock);
1204
1205 /* Find the directory for the ctl_table */
1206 for (name = path; name; name = nextname) {
1207 int namelen;
1208 nextname = strchr(name, '/');
1209 if (nextname) {
1210 namelen = nextname - name;
1211 nextname++;
1212 } else {
1213 namelen = strlen(name);
1214 }
1215 if (namelen == 0)
1216 continue;
1217
1218 dir = get_subdir(dir, name, namelen);
1219 if (IS_ERR(dir))
1220 goto fail;
1221 }
1222
1223 spin_lock(&sysctl_lock);
1224 if (insert_header(dir, header))
1225 goto fail_put_dir_locked;
1226
1227 drop_sysctl_table(&dir->header);
1228 spin_unlock(&sysctl_lock);
1229
1230 return header;
1231
1232fail_put_dir_locked:
1233 drop_sysctl_table(&dir->header);
1234 spin_unlock(&sysctl_lock);
1235fail:
1236 kfree(header);
1237 dump_stack();
1238 return NULL;
1239}
1240
1241/**
1242 * register_sysctl - register a sysctl table
1243 * @path: The path to the directory the sysctl table is in.
1244 * @table: the table structure
1245 *
1246 * Register a sysctl table. @table should be a filled in ctl_table
1247 * array. A completely 0 filled entry terminates the table.
1248 *
1249 * See __register_sysctl_table for more details.
1250 */
1251struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1252{
1253 return __register_sysctl_table(&sysctl_table_root.default_set,
1254 path, table);
1255}
1256EXPORT_SYMBOL(register_sysctl);
1257
1258static char *append_path(const char *path, char *pos, const char *name)
1259{
1260 int namelen;
1261 namelen = strlen(name);
1262 if (((pos - path) + namelen + 2) >= PATH_MAX)
1263 return NULL;
1264 memcpy(pos, name, namelen);
1265 pos[namelen] = '/';
1266 pos[namelen + 1] = '\0';
1267 pos += namelen + 1;
1268 return pos;
1269}
1270
1271static int count_subheaders(struct ctl_table *table)
1272{
1273 int has_files = 0;
1274 int nr_subheaders = 0;
1275 struct ctl_table *entry;
1276
1277 /* special case: no directory and empty directory */
1278 if (!table || !table->procname)
1279 return 1;
1280
1281 for (entry = table; entry->procname; entry++) {
1282 if (entry->child)
1283 nr_subheaders += count_subheaders(entry->child);
1284 else
1285 has_files = 1;
1286 }
1287 return nr_subheaders + has_files;
1288}
1289
1290static int register_leaf_sysctl_tables(const char *path, char *pos,
1291 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1292 struct ctl_table *table)
1293{
1294 struct ctl_table *ctl_table_arg = NULL;
1295 struct ctl_table *entry, *files;
1296 int nr_files = 0;
1297 int nr_dirs = 0;
1298 int err = -ENOMEM;
1299
1300 for (entry = table; entry->procname; entry++) {
1301 if (entry->child)
1302 nr_dirs++;
1303 else
1304 nr_files++;
1305 }
1306
1307 files = table;
1308 /* If there are mixed files and directories we need a new table */
1309 if (nr_dirs && nr_files) {
1310 struct ctl_table *new;
1311 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1312 GFP_KERNEL);
1313 if (!files)
1314 goto out;
1315
1316 ctl_table_arg = files;
1317 for (new = files, entry = table; entry->procname; entry++) {
1318 if (entry->child)
1319 continue;
1320 *new = *entry;
1321 new++;
1322 }
1323 }
1324
1325 /* Register everything except a directory full of subdirectories */
1326 if (nr_files || !nr_dirs) {
1327 struct ctl_table_header *header;
1328 header = __register_sysctl_table(set, path, files);
1329 if (!header) {
1330 kfree(ctl_table_arg);
1331 goto out;
1332 }
1333
1334 /* Remember if we need to free the file table */
1335 header->ctl_table_arg = ctl_table_arg;
1336 **subheader = header;
1337 (*subheader)++;
1338 }
1339
1340 /* Recurse into the subdirectories. */
1341 for (entry = table; entry->procname; entry++) {
1342 char *child_pos;
1343
1344 if (!entry->child)
1345 continue;
1346
1347 err = -ENAMETOOLONG;
1348 child_pos = append_path(path, pos, entry->procname);
1349 if (!child_pos)
1350 goto out;
1351
1352 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1353 set, entry->child);
1354 pos[0] = '\0';
1355 if (err)
1356 goto out;
1357 }
1358 err = 0;
1359out:
1360 /* On failure our caller will unregister all registered subheaders */
1361 return err;
1362}
1363
1364/**
1365 * __register_sysctl_paths - register a sysctl table hierarchy
1366 * @set: Sysctl tree to register on
1367 * @path: The path to the directory the sysctl table is in.
1368 * @table: the top-level table structure
1369 *
1370 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1371 * array. A completely 0 filled entry terminates the table.
1372 *
1373 * See __register_sysctl_table for more details.
1374 */
1375struct ctl_table_header *__register_sysctl_paths(
1376 struct ctl_table_set *set,
1377 const struct ctl_path *path, struct ctl_table *table)
1378{
1379 struct ctl_table *ctl_table_arg = table;
1380 int nr_subheaders = count_subheaders(table);
1381 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1382 const struct ctl_path *component;
1383 char *new_path, *pos;
1384
1385 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1386 if (!new_path)
1387 return NULL;
1388
1389 pos[0] = '\0';
1390 for (component = path; component->procname; component++) {
1391 pos = append_path(new_path, pos, component->procname);
1392 if (!pos)
1393 goto out;
1394 }
1395 while (table->procname && table->child && !table[1].procname) {
1396 pos = append_path(new_path, pos, table->procname);
1397 if (!pos)
1398 goto out;
1399 table = table->child;
1400 }
1401 if (nr_subheaders == 1) {
1402 header = __register_sysctl_table(set, new_path, table);
1403 if (header)
1404 header->ctl_table_arg = ctl_table_arg;
1405 } else {
1406 header = kzalloc(sizeof(*header) +
1407 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1408 if (!header)
1409 goto out;
1410
1411 subheaders = (struct ctl_table_header **) (header + 1);
1412 subheader = subheaders;
1413 header->ctl_table_arg = ctl_table_arg;
1414
1415 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1416 set, table))
1417 goto err_register_leaves;
1418 }
1419
1420out:
1421 kfree(new_path);
1422 return header;
1423
1424err_register_leaves:
1425 while (subheader > subheaders) {
1426 struct ctl_table_header *subh = *(--subheader);
1427 struct ctl_table *table = subh->ctl_table_arg;
1428 unregister_sysctl_table(subh);
1429 kfree(table);
1430 }
1431 kfree(header);
1432 header = NULL;
1433 goto out;
1434}
1435
1436/**
1437 * register_sysctl_table_path - register a sysctl table hierarchy
1438 * @path: The path to the directory the sysctl table is in.
1439 * @table: the top-level table structure
1440 *
1441 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1442 * array. A completely 0 filled entry terminates the table.
1443 *
1444 * See __register_sysctl_paths for more details.
1445 */
1446struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1447 struct ctl_table *table)
1448{
1449 return __register_sysctl_paths(&sysctl_table_root.default_set,
1450 path, table);
1451}
1452EXPORT_SYMBOL(register_sysctl_paths);
1453
1454/**
1455 * register_sysctl_table - register a sysctl table hierarchy
1456 * @table: the top-level table structure
1457 *
1458 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1459 * array. A completely 0 filled entry terminates the table.
1460 *
1461 * See register_sysctl_paths for more details.
1462 */
1463struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1464{
1465 static const struct ctl_path null_path[] = { {} };
1466
1467 return register_sysctl_paths(null_path, table);
1468}
1469EXPORT_SYMBOL(register_sysctl_table);
1470
1471static void put_links(struct ctl_table_header *header)
1472{
1473 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1474 struct ctl_table_root *root = header->root;
1475 struct ctl_dir *parent = header->parent;
1476 struct ctl_dir *core_parent;
1477 struct ctl_table *entry;
1478
1479 if (header->set == root_set)
1480 return;
1481
1482 core_parent = xlate_dir(root_set, parent);
1483 if (IS_ERR(core_parent))
1484 return;
1485
1486 for (entry = header->ctl_table; entry->procname; entry++) {
1487 struct ctl_table_header *link_head;
1488 struct ctl_table *link;
1489 const char *name = entry->procname;
1490
1491 link = find_entry(&link_head, core_parent, name, strlen(name));
1492 if (link &&
1493 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1494 (S_ISLNK(link->mode) && (link->data == root)))) {
1495 drop_sysctl_table(link_head);
1496 }
1497 else {
1498 pr_err("sysctl link missing during unregister: ");
1499 sysctl_print_dir(parent);
1500 pr_cont("/%s\n", name);
1501 }
1502 }
1503}
1504
1505static void drop_sysctl_table(struct ctl_table_header *header)
1506{
1507 struct ctl_dir *parent = header->parent;
1508
1509 if (--header->nreg)
1510 return;
1511
1512 put_links(header);
1513 start_unregistering(header);
1514 if (!--header->count)
1515 kfree_rcu(header, rcu);
1516
1517 if (parent)
1518 drop_sysctl_table(&parent->header);
1519}
1520
1521/**
1522 * unregister_sysctl_table - unregister a sysctl table hierarchy
1523 * @header: the header returned from register_sysctl_table
1524 *
1525 * Unregisters the sysctl table and all children. proc entries may not
1526 * actually be removed until they are no longer used by anyone.
1527 */
1528void unregister_sysctl_table(struct ctl_table_header * header)
1529{
1530 int nr_subheaders;
1531 might_sleep();
1532
1533 if (header == NULL)
1534 return;
1535
1536 nr_subheaders = count_subheaders(header->ctl_table_arg);
1537 if (unlikely(nr_subheaders > 1)) {
1538 struct ctl_table_header **subheaders;
1539 int i;
1540
1541 subheaders = (struct ctl_table_header **)(header + 1);
1542 for (i = nr_subheaders -1; i >= 0; i--) {
1543 struct ctl_table_header *subh = subheaders[i];
1544 struct ctl_table *table = subh->ctl_table_arg;
1545 unregister_sysctl_table(subh);
1546 kfree(table);
1547 }
1548 kfree(header);
1549 return;
1550 }
1551
1552 spin_lock(&sysctl_lock);
1553 drop_sysctl_table(header);
1554 spin_unlock(&sysctl_lock);
1555}
1556EXPORT_SYMBOL(unregister_sysctl_table);
1557
1558void setup_sysctl_set(struct ctl_table_set *set,
1559 struct ctl_table_root *root,
1560 int (*is_seen)(struct ctl_table_set *))
1561{
1562 memset(set, 0, sizeof(*set));
1563 set->is_seen = is_seen;
1564 init_header(&set->dir.header, root, set, NULL, root_table);
1565}
1566
1567void retire_sysctl_set(struct ctl_table_set *set)
1568{
1569 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1570}
1571
1572int __init proc_sys_init(void)
1573{
1574 struct proc_dir_entry *proc_sys_root;
1575
1576 proc_sys_root = proc_mkdir("sys", NULL);
1577 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1578 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1579 proc_sys_root->nlink = 0;
1580
1581 return sysctl_init();
1582}