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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, table) \
23 for ((entry) = (table); (entry)->procname; (entry)++)
24
25static const struct dentry_operations proc_sys_dentry_operations;
26static const struct file_operations proc_sys_file_operations;
27static const struct inode_operations proc_sys_inode_operations;
28static const struct file_operations proc_sys_dir_file_operations;
29static const struct inode_operations proc_sys_dir_operations;
30
31/* Support for permanently empty directories */
32
33struct ctl_table sysctl_mount_point[] = {
34 { }
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
51static bool is_empty_dir(struct ctl_table_header *head)
52{
53 return head->ctl_table[0].child == sysctl_mount_point;
54}
55
56static void set_empty_dir(struct ctl_dir *dir)
57{
58 dir->header.ctl_table[0].child = sysctl_mount_point;
59}
60
61static void clear_empty_dir(struct ctl_dir *dir)
62
63{
64 dir->header.ctl_table[0].child = NULL;
65}
66
67void proc_sys_poll_notify(struct ctl_table_poll *poll)
68{
69 if (!poll)
70 return;
71
72 atomic_inc(&poll->event);
73 wake_up_interruptible(&poll->wait);
74}
75
76static struct ctl_table root_table[] = {
77 {
78 .procname = "",
79 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
80 },
81 { }
82};
83static struct ctl_table_root sysctl_table_root = {
84 .default_set.dir.header = {
85 {{.count = 1,
86 .nreg = 1,
87 .ctl_table = root_table }},
88 .ctl_table_arg = root_table,
89 .root = &sysctl_table_root,
90 .set = &sysctl_table_root.default_set,
91 },
92};
93
94static DEFINE_SPINLOCK(sysctl_lock);
95
96static void drop_sysctl_table(struct ctl_table_header *header);
97static int sysctl_follow_link(struct ctl_table_header **phead,
98 struct ctl_table **pentry);
99static int insert_links(struct ctl_table_header *head);
100static void put_links(struct ctl_table_header *header);
101
102static void sysctl_print_dir(struct ctl_dir *dir)
103{
104 if (dir->header.parent)
105 sysctl_print_dir(dir->header.parent);
106 pr_cont("%s/", dir->header.ctl_table[0].procname);
107}
108
109static int namecmp(const char *name1, int len1, const char *name2, int len2)
110{
111 int cmp;
112
113 cmp = memcmp(name1, name2, min(len1, len2));
114 if (cmp == 0)
115 cmp = len1 - len2;
116 return cmp;
117}
118
119/* Called under sysctl_lock */
120static struct ctl_table *find_entry(struct ctl_table_header **phead,
121 struct ctl_dir *dir, const char *name, int namelen)
122{
123 struct ctl_table_header *head;
124 struct ctl_table *entry;
125 struct rb_node *node = dir->root.rb_node;
126
127 while (node)
128 {
129 struct ctl_node *ctl_node;
130 const char *procname;
131 int cmp;
132
133 ctl_node = rb_entry(node, struct ctl_node, node);
134 head = ctl_node->header;
135 entry = &head->ctl_table[ctl_node - head->node];
136 procname = entry->procname;
137
138 cmp = namecmp(name, namelen, procname, strlen(procname));
139 if (cmp < 0)
140 node = node->rb_left;
141 else if (cmp > 0)
142 node = node->rb_right;
143 else {
144 *phead = head;
145 return entry;
146 }
147 }
148 return NULL;
149}
150
151static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
152{
153 struct rb_node *node = &head->node[entry - head->ctl_table].node;
154 struct rb_node **p = &head->parent->root.rb_node;
155 struct rb_node *parent = NULL;
156 const char *name = entry->procname;
157 int namelen = strlen(name);
158
159 while (*p) {
160 struct ctl_table_header *parent_head;
161 struct ctl_table *parent_entry;
162 struct ctl_node *parent_node;
163 const char *parent_name;
164 int cmp;
165
166 parent = *p;
167 parent_node = rb_entry(parent, struct ctl_node, node);
168 parent_head = parent_node->header;
169 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
170 parent_name = parent_entry->procname;
171
172 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
173 if (cmp < 0)
174 p = &(*p)->rb_left;
175 else if (cmp > 0)
176 p = &(*p)->rb_right;
177 else {
178 pr_err("sysctl duplicate entry: ");
179 sysctl_print_dir(head->parent);
180 pr_cont("%s\n", entry->procname);
181 return -EEXIST;
182 }
183 }
184
185 rb_link_node(node, parent, p);
186 rb_insert_color(node, &head->parent->root);
187 return 0;
188}
189
190static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
191{
192 struct rb_node *node = &head->node[entry - head->ctl_table].node;
193
194 rb_erase(node, &head->parent->root);
195}
196
197static void init_header(struct ctl_table_header *head,
198 struct ctl_table_root *root, struct ctl_table_set *set,
199 struct ctl_node *node, struct ctl_table *table)
200{
201 head->ctl_table = table;
202 head->ctl_table_arg = table;
203 head->used = 0;
204 head->count = 1;
205 head->nreg = 1;
206 head->unregistering = NULL;
207 head->root = root;
208 head->set = set;
209 head->parent = NULL;
210 head->node = node;
211 INIT_HLIST_HEAD(&head->inodes);
212 if (node) {
213 struct ctl_table *entry;
214
215 list_for_each_table_entry(entry, table) {
216 node->header = head;
217 node++;
218 }
219 }
220}
221
222static void erase_header(struct ctl_table_header *head)
223{
224 struct ctl_table *entry;
225
226 list_for_each_table_entry(entry, head->ctl_table)
227 erase_entry(head, entry);
228}
229
230static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
231{
232 struct ctl_table *entry;
233 int err;
234
235 /* Is this a permanently empty directory? */
236 if (is_empty_dir(&dir->header))
237 return -EROFS;
238
239 /* Am I creating a permanently empty directory? */
240 if (header->ctl_table == sysctl_mount_point) {
241 if (!RB_EMPTY_ROOT(&dir->root))
242 return -EINVAL;
243 set_empty_dir(dir);
244 }
245
246 dir->header.nreg++;
247 header->parent = dir;
248 err = insert_links(header);
249 if (err)
250 goto fail_links;
251 list_for_each_table_entry(entry, header->ctl_table) {
252 err = insert_entry(header, entry);
253 if (err)
254 goto fail;
255 }
256 return 0;
257fail:
258 erase_header(header);
259 put_links(header);
260fail_links:
261 if (header->ctl_table == sysctl_mount_point)
262 clear_empty_dir(dir);
263 header->parent = NULL;
264 drop_sysctl_table(&dir->header);
265 return err;
266}
267
268/* called under sysctl_lock */
269static int use_table(struct ctl_table_header *p)
270{
271 if (unlikely(p->unregistering))
272 return 0;
273 p->used++;
274 return 1;
275}
276
277/* called under sysctl_lock */
278static void unuse_table(struct ctl_table_header *p)
279{
280 if (!--p->used)
281 if (unlikely(p->unregistering))
282 complete(p->unregistering);
283}
284
285static void proc_sys_invalidate_dcache(struct ctl_table_header *head)
286{
287 proc_invalidate_siblings_dcache(&head->inodes, &sysctl_lock);
288}
289
290/* called under sysctl_lock, will reacquire if has to wait */
291static void start_unregistering(struct ctl_table_header *p)
292{
293 /*
294 * if p->used is 0, nobody will ever touch that entry again;
295 * we'll eliminate all paths to it before dropping sysctl_lock
296 */
297 if (unlikely(p->used)) {
298 struct completion wait;
299 init_completion(&wait);
300 p->unregistering = &wait;
301 spin_unlock(&sysctl_lock);
302 wait_for_completion(&wait);
303 } else {
304 /* anything non-NULL; we'll never dereference it */
305 p->unregistering = ERR_PTR(-EINVAL);
306 spin_unlock(&sysctl_lock);
307 }
308 /*
309 * Invalidate dentries for unregistered sysctls: namespaced sysctls
310 * can have duplicate names and contaminate dcache very badly.
311 */
312 proc_sys_invalidate_dcache(p);
313 /*
314 * do not remove from the list until nobody holds it; walking the
315 * list in do_sysctl() relies on that.
316 */
317 spin_lock(&sysctl_lock);
318 erase_header(p);
319}
320
321static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
322{
323 BUG_ON(!head);
324 spin_lock(&sysctl_lock);
325 if (!use_table(head))
326 head = ERR_PTR(-ENOENT);
327 spin_unlock(&sysctl_lock);
328 return head;
329}
330
331static void sysctl_head_finish(struct ctl_table_header *head)
332{
333 if (!head)
334 return;
335 spin_lock(&sysctl_lock);
336 unuse_table(head);
337 spin_unlock(&sysctl_lock);
338}
339
340static struct ctl_table_set *
341lookup_header_set(struct ctl_table_root *root)
342{
343 struct ctl_table_set *set = &root->default_set;
344 if (root->lookup)
345 set = root->lookup(root);
346 return set;
347}
348
349static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
350 struct ctl_dir *dir,
351 const char *name, int namelen)
352{
353 struct ctl_table_header *head;
354 struct ctl_table *entry;
355
356 spin_lock(&sysctl_lock);
357 entry = find_entry(&head, dir, name, namelen);
358 if (entry && use_table(head))
359 *phead = head;
360 else
361 entry = NULL;
362 spin_unlock(&sysctl_lock);
363 return entry;
364}
365
366static struct ctl_node *first_usable_entry(struct rb_node *node)
367{
368 struct ctl_node *ctl_node;
369
370 for (;node; node = rb_next(node)) {
371 ctl_node = rb_entry(node, struct ctl_node, node);
372 if (use_table(ctl_node->header))
373 return ctl_node;
374 }
375 return NULL;
376}
377
378static void first_entry(struct ctl_dir *dir,
379 struct ctl_table_header **phead, struct ctl_table **pentry)
380{
381 struct ctl_table_header *head = NULL;
382 struct ctl_table *entry = NULL;
383 struct ctl_node *ctl_node;
384
385 spin_lock(&sysctl_lock);
386 ctl_node = first_usable_entry(rb_first(&dir->root));
387 spin_unlock(&sysctl_lock);
388 if (ctl_node) {
389 head = ctl_node->header;
390 entry = &head->ctl_table[ctl_node - head->node];
391 }
392 *phead = head;
393 *pentry = entry;
394}
395
396static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
397{
398 struct ctl_table_header *head = *phead;
399 struct ctl_table *entry = *pentry;
400 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
401
402 spin_lock(&sysctl_lock);
403 unuse_table(head);
404
405 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
406 spin_unlock(&sysctl_lock);
407 head = NULL;
408 if (ctl_node) {
409 head = ctl_node->header;
410 entry = &head->ctl_table[ctl_node - head->node];
411 }
412 *phead = head;
413 *pentry = entry;
414}
415
416/*
417 * sysctl_perm does NOT grant the superuser all rights automatically, because
418 * some sysctl variables are readonly even to root.
419 */
420
421static int test_perm(int mode, int op)
422{
423 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
424 mode >>= 6;
425 else if (in_egroup_p(GLOBAL_ROOT_GID))
426 mode >>= 3;
427 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
428 return 0;
429 return -EACCES;
430}
431
432static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
433{
434 struct ctl_table_root *root = head->root;
435 int mode;
436
437 if (root->permissions)
438 mode = root->permissions(head, table);
439 else
440 mode = table->mode;
441
442 return test_perm(mode, op);
443}
444
445static struct inode *proc_sys_make_inode(struct super_block *sb,
446 struct ctl_table_header *head, struct ctl_table *table)
447{
448 struct ctl_table_root *root = head->root;
449 struct inode *inode;
450 struct proc_inode *ei;
451
452 inode = new_inode(sb);
453 if (!inode)
454 return ERR_PTR(-ENOMEM);
455
456 inode->i_ino = get_next_ino();
457
458 ei = PROC_I(inode);
459
460 spin_lock(&sysctl_lock);
461 if (unlikely(head->unregistering)) {
462 spin_unlock(&sysctl_lock);
463 iput(inode);
464 return ERR_PTR(-ENOENT);
465 }
466 ei->sysctl = head;
467 ei->sysctl_entry = table;
468 hlist_add_head_rcu(&ei->sibling_inodes, &head->inodes);
469 head->count++;
470 spin_unlock(&sysctl_lock);
471
472 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
473 inode->i_mode = table->mode;
474 if (!S_ISDIR(table->mode)) {
475 inode->i_mode |= S_IFREG;
476 inode->i_op = &proc_sys_inode_operations;
477 inode->i_fop = &proc_sys_file_operations;
478 } else {
479 inode->i_mode |= S_IFDIR;
480 inode->i_op = &proc_sys_dir_operations;
481 inode->i_fop = &proc_sys_dir_file_operations;
482 if (is_empty_dir(head))
483 make_empty_dir_inode(inode);
484 }
485
486 if (root->set_ownership)
487 root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
488 else {
489 inode->i_uid = GLOBAL_ROOT_UID;
490 inode->i_gid = GLOBAL_ROOT_GID;
491 }
492
493 return inode;
494}
495
496void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
497{
498 spin_lock(&sysctl_lock);
499 hlist_del_init_rcu(&PROC_I(inode)->sibling_inodes);
500 if (!--head->count)
501 kfree_rcu(head, rcu);
502 spin_unlock(&sysctl_lock);
503}
504
505static struct ctl_table_header *grab_header(struct inode *inode)
506{
507 struct ctl_table_header *head = PROC_I(inode)->sysctl;
508 if (!head)
509 head = &sysctl_table_root.default_set.dir.header;
510 return sysctl_head_grab(head);
511}
512
513static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
514 unsigned int flags)
515{
516 struct ctl_table_header *head = grab_header(dir);
517 struct ctl_table_header *h = NULL;
518 const struct qstr *name = &dentry->d_name;
519 struct ctl_table *p;
520 struct inode *inode;
521 struct dentry *err = ERR_PTR(-ENOENT);
522 struct ctl_dir *ctl_dir;
523 int ret;
524
525 if (IS_ERR(head))
526 return ERR_CAST(head);
527
528 ctl_dir = container_of(head, struct ctl_dir, header);
529
530 p = lookup_entry(&h, ctl_dir, name->name, name->len);
531 if (!p)
532 goto out;
533
534 if (S_ISLNK(p->mode)) {
535 ret = sysctl_follow_link(&h, &p);
536 err = ERR_PTR(ret);
537 if (ret)
538 goto out;
539 }
540
541 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
542 if (IS_ERR(inode)) {
543 err = ERR_CAST(inode);
544 goto out;
545 }
546
547 d_set_d_op(dentry, &proc_sys_dentry_operations);
548 err = d_splice_alias(inode, dentry);
549
550out:
551 if (h)
552 sysctl_head_finish(h);
553 sysctl_head_finish(head);
554 return err;
555}
556
557static ssize_t proc_sys_call_handler(struct kiocb *iocb, struct iov_iter *iter,
558 int write)
559{
560 struct inode *inode = file_inode(iocb->ki_filp);
561 struct ctl_table_header *head = grab_header(inode);
562 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
563 size_t count = iov_iter_count(iter);
564 char *kbuf;
565 ssize_t error;
566
567 if (IS_ERR(head))
568 return PTR_ERR(head);
569
570 /*
571 * At this point we know that the sysctl was not unregistered
572 * and won't be until we finish.
573 */
574 error = -EPERM;
575 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
576 goto out;
577
578 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
579 error = -EINVAL;
580 if (!table->proc_handler)
581 goto out;
582
583 /* don't even try if the size is too large */
584 error = -ENOMEM;
585 if (count >= KMALLOC_MAX_SIZE)
586 goto out;
587 kbuf = kvzalloc(count + 1, GFP_KERNEL);
588 if (!kbuf)
589 goto out;
590
591 if (write) {
592 error = -EFAULT;
593 if (!copy_from_iter_full(kbuf, count, iter))
594 goto out_free_buf;
595 kbuf[count] = '\0';
596 }
597
598 error = BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, &kbuf, &count,
599 &iocb->ki_pos);
600 if (error)
601 goto out_free_buf;
602
603 /* careful: calling conventions are nasty here */
604 error = table->proc_handler(table, write, kbuf, &count, &iocb->ki_pos);
605 if (error)
606 goto out_free_buf;
607
608 if (!write) {
609 error = -EFAULT;
610 if (copy_to_iter(kbuf, count, iter) < count)
611 goto out_free_buf;
612 }
613
614 error = count;
615out_free_buf:
616 kvfree(kbuf);
617out:
618 sysctl_head_finish(head);
619
620 return error;
621}
622
623static ssize_t proc_sys_read(struct kiocb *iocb, struct iov_iter *iter)
624{
625 return proc_sys_call_handler(iocb, iter, 0);
626}
627
628static ssize_t proc_sys_write(struct kiocb *iocb, struct iov_iter *iter)
629{
630 return proc_sys_call_handler(iocb, iter, 1);
631}
632
633static int proc_sys_open(struct inode *inode, struct file *filp)
634{
635 struct ctl_table_header *head = grab_header(inode);
636 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
637
638 /* sysctl was unregistered */
639 if (IS_ERR(head))
640 return PTR_ERR(head);
641
642 if (table->poll)
643 filp->private_data = proc_sys_poll_event(table->poll);
644
645 sysctl_head_finish(head);
646
647 return 0;
648}
649
650static __poll_t proc_sys_poll(struct file *filp, poll_table *wait)
651{
652 struct inode *inode = file_inode(filp);
653 struct ctl_table_header *head = grab_header(inode);
654 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
655 __poll_t ret = DEFAULT_POLLMASK;
656 unsigned long event;
657
658 /* sysctl was unregistered */
659 if (IS_ERR(head))
660 return EPOLLERR | EPOLLHUP;
661
662 if (!table->proc_handler)
663 goto out;
664
665 if (!table->poll)
666 goto out;
667
668 event = (unsigned long)filp->private_data;
669 poll_wait(filp, &table->poll->wait, wait);
670
671 if (event != atomic_read(&table->poll->event)) {
672 filp->private_data = proc_sys_poll_event(table->poll);
673 ret = EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI;
674 }
675
676out:
677 sysctl_head_finish(head);
678
679 return ret;
680}
681
682static bool proc_sys_fill_cache(struct file *file,
683 struct dir_context *ctx,
684 struct ctl_table_header *head,
685 struct ctl_table *table)
686{
687 struct dentry *child, *dir = file->f_path.dentry;
688 struct inode *inode;
689 struct qstr qname;
690 ino_t ino = 0;
691 unsigned type = DT_UNKNOWN;
692
693 qname.name = table->procname;
694 qname.len = strlen(table->procname);
695 qname.hash = full_name_hash(dir, qname.name, qname.len);
696
697 child = d_lookup(dir, &qname);
698 if (!child) {
699 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
700 child = d_alloc_parallel(dir, &qname, &wq);
701 if (IS_ERR(child))
702 return false;
703 if (d_in_lookup(child)) {
704 struct dentry *res;
705 inode = proc_sys_make_inode(dir->d_sb, head, table);
706 if (IS_ERR(inode)) {
707 d_lookup_done(child);
708 dput(child);
709 return false;
710 }
711 d_set_d_op(child, &proc_sys_dentry_operations);
712 res = d_splice_alias(inode, child);
713 d_lookup_done(child);
714 if (unlikely(res)) {
715 if (IS_ERR(res)) {
716 dput(child);
717 return false;
718 }
719 dput(child);
720 child = res;
721 }
722 }
723 }
724 inode = d_inode(child);
725 ino = inode->i_ino;
726 type = inode->i_mode >> 12;
727 dput(child);
728 return dir_emit(ctx, qname.name, qname.len, ino, type);
729}
730
731static bool proc_sys_link_fill_cache(struct file *file,
732 struct dir_context *ctx,
733 struct ctl_table_header *head,
734 struct ctl_table *table)
735{
736 bool ret = true;
737
738 head = sysctl_head_grab(head);
739 if (IS_ERR(head))
740 return false;
741
742 /* It is not an error if we can not follow the link ignore it */
743 if (sysctl_follow_link(&head, &table))
744 goto out;
745
746 ret = proc_sys_fill_cache(file, ctx, head, table);
747out:
748 sysctl_head_finish(head);
749 return ret;
750}
751
752static int scan(struct ctl_table_header *head, struct ctl_table *table,
753 unsigned long *pos, struct file *file,
754 struct dir_context *ctx)
755{
756 bool res;
757
758 if ((*pos)++ < ctx->pos)
759 return true;
760
761 if (unlikely(S_ISLNK(table->mode)))
762 res = proc_sys_link_fill_cache(file, ctx, head, table);
763 else
764 res = proc_sys_fill_cache(file, ctx, head, table);
765
766 if (res)
767 ctx->pos = *pos;
768
769 return res;
770}
771
772static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
773{
774 struct ctl_table_header *head = grab_header(file_inode(file));
775 struct ctl_table_header *h = NULL;
776 struct ctl_table *entry;
777 struct ctl_dir *ctl_dir;
778 unsigned long pos;
779
780 if (IS_ERR(head))
781 return PTR_ERR(head);
782
783 ctl_dir = container_of(head, struct ctl_dir, header);
784
785 if (!dir_emit_dots(file, ctx))
786 goto out;
787
788 pos = 2;
789
790 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
791 if (!scan(h, entry, &pos, file, ctx)) {
792 sysctl_head_finish(h);
793 break;
794 }
795 }
796out:
797 sysctl_head_finish(head);
798 return 0;
799}
800
801static int proc_sys_permission(struct user_namespace *mnt_userns,
802 struct inode *inode, int mask)
803{
804 /*
805 * sysctl entries that are not writeable,
806 * are _NOT_ writeable, capabilities or not.
807 */
808 struct ctl_table_header *head;
809 struct ctl_table *table;
810 int error;
811
812 /* Executable files are not allowed under /proc/sys/ */
813 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
814 return -EACCES;
815
816 head = grab_header(inode);
817 if (IS_ERR(head))
818 return PTR_ERR(head);
819
820 table = PROC_I(inode)->sysctl_entry;
821 if (!table) /* global root - r-xr-xr-x */
822 error = mask & MAY_WRITE ? -EACCES : 0;
823 else /* Use the permissions on the sysctl table entry */
824 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
825
826 sysctl_head_finish(head);
827 return error;
828}
829
830static int proc_sys_setattr(struct user_namespace *mnt_userns,
831 struct dentry *dentry, struct iattr *attr)
832{
833 struct inode *inode = d_inode(dentry);
834 int error;
835
836 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
837 return -EPERM;
838
839 error = setattr_prepare(&init_user_ns, dentry, attr);
840 if (error)
841 return error;
842
843 setattr_copy(&init_user_ns, inode, attr);
844 mark_inode_dirty(inode);
845 return 0;
846}
847
848static int proc_sys_getattr(struct user_namespace *mnt_userns,
849 const struct path *path, struct kstat *stat,
850 u32 request_mask, unsigned int query_flags)
851{
852 struct inode *inode = d_inode(path->dentry);
853 struct ctl_table_header *head = grab_header(inode);
854 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
855
856 if (IS_ERR(head))
857 return PTR_ERR(head);
858
859 generic_fillattr(&init_user_ns, inode, stat);
860 if (table)
861 stat->mode = (stat->mode & S_IFMT) | table->mode;
862
863 sysctl_head_finish(head);
864 return 0;
865}
866
867static const struct file_operations proc_sys_file_operations = {
868 .open = proc_sys_open,
869 .poll = proc_sys_poll,
870 .read_iter = proc_sys_read,
871 .write_iter = proc_sys_write,
872 .splice_read = generic_file_splice_read,
873 .splice_write = iter_file_splice_write,
874 .llseek = default_llseek,
875};
876
877static const struct file_operations proc_sys_dir_file_operations = {
878 .read = generic_read_dir,
879 .iterate_shared = proc_sys_readdir,
880 .llseek = generic_file_llseek,
881};
882
883static const struct inode_operations proc_sys_inode_operations = {
884 .permission = proc_sys_permission,
885 .setattr = proc_sys_setattr,
886 .getattr = proc_sys_getattr,
887};
888
889static const struct inode_operations proc_sys_dir_operations = {
890 .lookup = proc_sys_lookup,
891 .permission = proc_sys_permission,
892 .setattr = proc_sys_setattr,
893 .getattr = proc_sys_getattr,
894};
895
896static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
897{
898 if (flags & LOOKUP_RCU)
899 return -ECHILD;
900 return !PROC_I(d_inode(dentry))->sysctl->unregistering;
901}
902
903static int proc_sys_delete(const struct dentry *dentry)
904{
905 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
906}
907
908static int sysctl_is_seen(struct ctl_table_header *p)
909{
910 struct ctl_table_set *set = p->set;
911 int res;
912 spin_lock(&sysctl_lock);
913 if (p->unregistering)
914 res = 0;
915 else if (!set->is_seen)
916 res = 1;
917 else
918 res = set->is_seen(set);
919 spin_unlock(&sysctl_lock);
920 return res;
921}
922
923static int proc_sys_compare(const struct dentry *dentry,
924 unsigned int len, const char *str, const struct qstr *name)
925{
926 struct ctl_table_header *head;
927 struct inode *inode;
928
929 /* Although proc doesn't have negative dentries, rcu-walk means
930 * that inode here can be NULL */
931 /* AV: can it, indeed? */
932 inode = d_inode_rcu(dentry);
933 if (!inode)
934 return 1;
935 if (name->len != len)
936 return 1;
937 if (memcmp(name->name, str, len))
938 return 1;
939 head = rcu_dereference(PROC_I(inode)->sysctl);
940 return !head || !sysctl_is_seen(head);
941}
942
943static const struct dentry_operations proc_sys_dentry_operations = {
944 .d_revalidate = proc_sys_revalidate,
945 .d_delete = proc_sys_delete,
946 .d_compare = proc_sys_compare,
947};
948
949static struct ctl_dir *find_subdir(struct ctl_dir *dir,
950 const char *name, int namelen)
951{
952 struct ctl_table_header *head;
953 struct ctl_table *entry;
954
955 entry = find_entry(&head, dir, name, namelen);
956 if (!entry)
957 return ERR_PTR(-ENOENT);
958 if (!S_ISDIR(entry->mode))
959 return ERR_PTR(-ENOTDIR);
960 return container_of(head, struct ctl_dir, header);
961}
962
963static struct ctl_dir *new_dir(struct ctl_table_set *set,
964 const char *name, int namelen)
965{
966 struct ctl_table *table;
967 struct ctl_dir *new;
968 struct ctl_node *node;
969 char *new_name;
970
971 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
972 sizeof(struct ctl_table)*2 + namelen + 1,
973 GFP_KERNEL);
974 if (!new)
975 return NULL;
976
977 node = (struct ctl_node *)(new + 1);
978 table = (struct ctl_table *)(node + 1);
979 new_name = (char *)(table + 2);
980 memcpy(new_name, name, namelen);
981 table[0].procname = new_name;
982 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
983 init_header(&new->header, set->dir.header.root, set, node, table);
984
985 return new;
986}
987
988/**
989 * get_subdir - find or create a subdir with the specified name.
990 * @dir: Directory to create the subdirectory in
991 * @name: The name of the subdirectory to find or create
992 * @namelen: The length of name
993 *
994 * Takes a directory with an elevated reference count so we know that
995 * if we drop the lock the directory will not go away. Upon success
996 * the reference is moved from @dir to the returned subdirectory.
997 * Upon error an error code is returned and the reference on @dir is
998 * simply dropped.
999 */
1000static struct ctl_dir *get_subdir(struct ctl_dir *dir,
1001 const char *name, int namelen)
1002{
1003 struct ctl_table_set *set = dir->header.set;
1004 struct ctl_dir *subdir, *new = NULL;
1005 int err;
1006
1007 spin_lock(&sysctl_lock);
1008 subdir = find_subdir(dir, name, namelen);
1009 if (!IS_ERR(subdir))
1010 goto found;
1011 if (PTR_ERR(subdir) != -ENOENT)
1012 goto failed;
1013
1014 spin_unlock(&sysctl_lock);
1015 new = new_dir(set, name, namelen);
1016 spin_lock(&sysctl_lock);
1017 subdir = ERR_PTR(-ENOMEM);
1018 if (!new)
1019 goto failed;
1020
1021 /* Was the subdir added while we dropped the lock? */
1022 subdir = find_subdir(dir, name, namelen);
1023 if (!IS_ERR(subdir))
1024 goto found;
1025 if (PTR_ERR(subdir) != -ENOENT)
1026 goto failed;
1027
1028 /* Nope. Use the our freshly made directory entry. */
1029 err = insert_header(dir, &new->header);
1030 subdir = ERR_PTR(err);
1031 if (err)
1032 goto failed;
1033 subdir = new;
1034found:
1035 subdir->header.nreg++;
1036failed:
1037 if (IS_ERR(subdir)) {
1038 pr_err("sysctl could not get directory: ");
1039 sysctl_print_dir(dir);
1040 pr_cont("%*.*s %ld\n", namelen, namelen, name,
1041 PTR_ERR(subdir));
1042 }
1043 drop_sysctl_table(&dir->header);
1044 if (new)
1045 drop_sysctl_table(&new->header);
1046 spin_unlock(&sysctl_lock);
1047 return subdir;
1048}
1049
1050static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
1051{
1052 struct ctl_dir *parent;
1053 const char *procname;
1054 if (!dir->header.parent)
1055 return &set->dir;
1056 parent = xlate_dir(set, dir->header.parent);
1057 if (IS_ERR(parent))
1058 return parent;
1059 procname = dir->header.ctl_table[0].procname;
1060 return find_subdir(parent, procname, strlen(procname));
1061}
1062
1063static int sysctl_follow_link(struct ctl_table_header **phead,
1064 struct ctl_table **pentry)
1065{
1066 struct ctl_table_header *head;
1067 struct ctl_table_root *root;
1068 struct ctl_table_set *set;
1069 struct ctl_table *entry;
1070 struct ctl_dir *dir;
1071 int ret;
1072
1073 spin_lock(&sysctl_lock);
1074 root = (*pentry)->data;
1075 set = lookup_header_set(root);
1076 dir = xlate_dir(set, (*phead)->parent);
1077 if (IS_ERR(dir))
1078 ret = PTR_ERR(dir);
1079 else {
1080 const char *procname = (*pentry)->procname;
1081 head = NULL;
1082 entry = find_entry(&head, dir, procname, strlen(procname));
1083 ret = -ENOENT;
1084 if (entry && use_table(head)) {
1085 unuse_table(*phead);
1086 *phead = head;
1087 *pentry = entry;
1088 ret = 0;
1089 }
1090 }
1091
1092 spin_unlock(&sysctl_lock);
1093 return ret;
1094}
1095
1096static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
1097{
1098 struct va_format vaf;
1099 va_list args;
1100
1101 va_start(args, fmt);
1102 vaf.fmt = fmt;
1103 vaf.va = &args;
1104
1105 pr_err("sysctl table check failed: %s/%s %pV\n",
1106 path, table->procname, &vaf);
1107
1108 va_end(args);
1109 return -EINVAL;
1110}
1111
1112static int sysctl_check_table_array(const char *path, struct ctl_table *table)
1113{
1114 int err = 0;
1115
1116 if ((table->proc_handler == proc_douintvec) ||
1117 (table->proc_handler == proc_douintvec_minmax)) {
1118 if (table->maxlen != sizeof(unsigned int))
1119 err |= sysctl_err(path, table, "array not allowed");
1120 }
1121
1122 if (table->proc_handler == proc_dou8vec_minmax) {
1123 if (table->maxlen != sizeof(u8))
1124 err |= sysctl_err(path, table, "array not allowed");
1125 }
1126
1127 return err;
1128}
1129
1130static int sysctl_check_table(const char *path, struct ctl_table *table)
1131{
1132 struct ctl_table *entry;
1133 int err = 0;
1134 list_for_each_table_entry(entry, table) {
1135 if (entry->child)
1136 err |= sysctl_err(path, entry, "Not a file");
1137
1138 if ((entry->proc_handler == proc_dostring) ||
1139 (entry->proc_handler == proc_dointvec) ||
1140 (entry->proc_handler == proc_douintvec) ||
1141 (entry->proc_handler == proc_douintvec_minmax) ||
1142 (entry->proc_handler == proc_dointvec_minmax) ||
1143 (entry->proc_handler == proc_dou8vec_minmax) ||
1144 (entry->proc_handler == proc_dointvec_jiffies) ||
1145 (entry->proc_handler == proc_dointvec_userhz_jiffies) ||
1146 (entry->proc_handler == proc_dointvec_ms_jiffies) ||
1147 (entry->proc_handler == proc_doulongvec_minmax) ||
1148 (entry->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1149 if (!entry->data)
1150 err |= sysctl_err(path, entry, "No data");
1151 if (!entry->maxlen)
1152 err |= sysctl_err(path, entry, "No maxlen");
1153 else
1154 err |= sysctl_check_table_array(path, entry);
1155 }
1156 if (!entry->proc_handler)
1157 err |= sysctl_err(path, entry, "No proc_handler");
1158
1159 if ((entry->mode & (S_IRUGO|S_IWUGO)) != entry->mode)
1160 err |= sysctl_err(path, entry, "bogus .mode 0%o",
1161 entry->mode);
1162 }
1163 return err;
1164}
1165
1166static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1167 struct ctl_table_root *link_root)
1168{
1169 struct ctl_table *link_table, *entry, *link;
1170 struct ctl_table_header *links;
1171 struct ctl_node *node;
1172 char *link_name;
1173 int nr_entries, name_bytes;
1174
1175 name_bytes = 0;
1176 nr_entries = 0;
1177 list_for_each_table_entry(entry, table) {
1178 nr_entries++;
1179 name_bytes += strlen(entry->procname) + 1;
1180 }
1181
1182 links = kzalloc(sizeof(struct ctl_table_header) +
1183 sizeof(struct ctl_node)*nr_entries +
1184 sizeof(struct ctl_table)*(nr_entries + 1) +
1185 name_bytes,
1186 GFP_KERNEL);
1187
1188 if (!links)
1189 return NULL;
1190
1191 node = (struct ctl_node *)(links + 1);
1192 link_table = (struct ctl_table *)(node + nr_entries);
1193 link_name = (char *)&link_table[nr_entries + 1];
1194 link = link_table;
1195
1196 list_for_each_table_entry(entry, table) {
1197 int len = strlen(entry->procname) + 1;
1198 memcpy(link_name, entry->procname, len);
1199 link->procname = link_name;
1200 link->mode = S_IFLNK|S_IRWXUGO;
1201 link->data = link_root;
1202 link_name += len;
1203 link++;
1204 }
1205 init_header(links, dir->header.root, dir->header.set, node, link_table);
1206 links->nreg = nr_entries;
1207
1208 return links;
1209}
1210
1211static bool get_links(struct ctl_dir *dir,
1212 struct ctl_table *table, struct ctl_table_root *link_root)
1213{
1214 struct ctl_table_header *head;
1215 struct ctl_table *entry, *link;
1216
1217 /* Are there links available for every entry in table? */
1218 list_for_each_table_entry(entry, table) {
1219 const char *procname = entry->procname;
1220 link = find_entry(&head, dir, procname, strlen(procname));
1221 if (!link)
1222 return false;
1223 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1224 continue;
1225 if (S_ISLNK(link->mode) && (link->data == link_root))
1226 continue;
1227 return false;
1228 }
1229
1230 /* The checks passed. Increase the registration count on the links */
1231 list_for_each_table_entry(entry, table) {
1232 const char *procname = entry->procname;
1233 link = find_entry(&head, dir, procname, strlen(procname));
1234 head->nreg++;
1235 }
1236 return true;
1237}
1238
1239static int insert_links(struct ctl_table_header *head)
1240{
1241 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1242 struct ctl_dir *core_parent;
1243 struct ctl_table_header *links;
1244 int err;
1245
1246 if (head->set == root_set)
1247 return 0;
1248
1249 core_parent = xlate_dir(root_set, head->parent);
1250 if (IS_ERR(core_parent))
1251 return 0;
1252
1253 if (get_links(core_parent, head->ctl_table, head->root))
1254 return 0;
1255
1256 core_parent->header.nreg++;
1257 spin_unlock(&sysctl_lock);
1258
1259 links = new_links(core_parent, head->ctl_table, head->root);
1260
1261 spin_lock(&sysctl_lock);
1262 err = -ENOMEM;
1263 if (!links)
1264 goto out;
1265
1266 err = 0;
1267 if (get_links(core_parent, head->ctl_table, head->root)) {
1268 kfree(links);
1269 goto out;
1270 }
1271
1272 err = insert_header(core_parent, links);
1273 if (err)
1274 kfree(links);
1275out:
1276 drop_sysctl_table(&core_parent->header);
1277 return err;
1278}
1279
1280/**
1281 * __register_sysctl_table - register a leaf sysctl table
1282 * @set: Sysctl tree to register on
1283 * @path: The path to the directory the sysctl table is in.
1284 * @table: the top-level table structure
1285 *
1286 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1287 * array. A completely 0 filled entry terminates the table.
1288 *
1289 * The members of the &struct ctl_table structure are used as follows:
1290 *
1291 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1292 * enter a sysctl file
1293 *
1294 * data - a pointer to data for use by proc_handler
1295 *
1296 * maxlen - the maximum size in bytes of the data
1297 *
1298 * mode - the file permissions for the /proc/sys file
1299 *
1300 * child - must be %NULL.
1301 *
1302 * proc_handler - the text handler routine (described below)
1303 *
1304 * extra1, extra2 - extra pointers usable by the proc handler routines
1305 *
1306 * Leaf nodes in the sysctl tree will be represented by a single file
1307 * under /proc; non-leaf nodes will be represented by directories.
1308 *
1309 * There must be a proc_handler routine for any terminal nodes.
1310 * Several default handlers are available to cover common cases -
1311 *
1312 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1313 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1314 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1315 *
1316 * It is the handler's job to read the input buffer from user memory
1317 * and process it. The handler should return 0 on success.
1318 *
1319 * This routine returns %NULL on a failure to register, and a pointer
1320 * to the table header on success.
1321 */
1322struct ctl_table_header *__register_sysctl_table(
1323 struct ctl_table_set *set,
1324 const char *path, struct ctl_table *table)
1325{
1326 struct ctl_table_root *root = set->dir.header.root;
1327 struct ctl_table_header *header;
1328 const char *name, *nextname;
1329 struct ctl_dir *dir;
1330 struct ctl_table *entry;
1331 struct ctl_node *node;
1332 int nr_entries = 0;
1333
1334 list_for_each_table_entry(entry, table)
1335 nr_entries++;
1336
1337 header = kzalloc(sizeof(struct ctl_table_header) +
1338 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL_ACCOUNT);
1339 if (!header)
1340 return NULL;
1341
1342 node = (struct ctl_node *)(header + 1);
1343 init_header(header, root, set, node, table);
1344 if (sysctl_check_table(path, table))
1345 goto fail;
1346
1347 spin_lock(&sysctl_lock);
1348 dir = &set->dir;
1349 /* Reference moved down the diretory tree get_subdir */
1350 dir->header.nreg++;
1351 spin_unlock(&sysctl_lock);
1352
1353 /* Find the directory for the ctl_table */
1354 for (name = path; name; name = nextname) {
1355 int namelen;
1356 nextname = strchr(name, '/');
1357 if (nextname) {
1358 namelen = nextname - name;
1359 nextname++;
1360 } else {
1361 namelen = strlen(name);
1362 }
1363 if (namelen == 0)
1364 continue;
1365
1366 dir = get_subdir(dir, name, namelen);
1367 if (IS_ERR(dir))
1368 goto fail;
1369 }
1370
1371 spin_lock(&sysctl_lock);
1372 if (insert_header(dir, header))
1373 goto fail_put_dir_locked;
1374
1375 drop_sysctl_table(&dir->header);
1376 spin_unlock(&sysctl_lock);
1377
1378 return header;
1379
1380fail_put_dir_locked:
1381 drop_sysctl_table(&dir->header);
1382 spin_unlock(&sysctl_lock);
1383fail:
1384 kfree(header);
1385 dump_stack();
1386 return NULL;
1387}
1388
1389/**
1390 * register_sysctl - register a sysctl table
1391 * @path: The path to the directory the sysctl table is in.
1392 * @table: the table structure
1393 *
1394 * Register a sysctl table. @table should be a filled in ctl_table
1395 * array. A completely 0 filled entry terminates the table.
1396 *
1397 * See __register_sysctl_table for more details.
1398 */
1399struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1400{
1401 return __register_sysctl_table(&sysctl_table_root.default_set,
1402 path, table);
1403}
1404EXPORT_SYMBOL(register_sysctl);
1405
1406/**
1407 * __register_sysctl_init() - register sysctl table to path
1408 * @path: path name for sysctl base
1409 * @table: This is the sysctl table that needs to be registered to the path
1410 * @table_name: The name of sysctl table, only used for log printing when
1411 * registration fails
1412 *
1413 * The sysctl interface is used by userspace to query or modify at runtime
1414 * a predefined value set on a variable. These variables however have default
1415 * values pre-set. Code which depends on these variables will always work even
1416 * if register_sysctl() fails. If register_sysctl() fails you'd just loose the
1417 * ability to query or modify the sysctls dynamically at run time. Chances of
1418 * register_sysctl() failing on init are extremely low, and so for both reasons
1419 * this function does not return any error as it is used by initialization code.
1420 *
1421 * Context: Can only be called after your respective sysctl base path has been
1422 * registered. So for instance, most base directories are registered early on
1423 * init before init levels are processed through proc_sys_init() and
1424 * sysctl_init_bases().
1425 */
1426void __init __register_sysctl_init(const char *path, struct ctl_table *table,
1427 const char *table_name)
1428{
1429 struct ctl_table_header *hdr = register_sysctl(path, table);
1430
1431 if (unlikely(!hdr)) {
1432 pr_err("failed when register_sysctl %s to %s\n", table_name, path);
1433 return;
1434 }
1435 kmemleak_not_leak(hdr);
1436}
1437
1438static char *append_path(const char *path, char *pos, const char *name)
1439{
1440 int namelen;
1441 namelen = strlen(name);
1442 if (((pos - path) + namelen + 2) >= PATH_MAX)
1443 return NULL;
1444 memcpy(pos, name, namelen);
1445 pos[namelen] = '/';
1446 pos[namelen + 1] = '\0';
1447 pos += namelen + 1;
1448 return pos;
1449}
1450
1451static int count_subheaders(struct ctl_table *table)
1452{
1453 int has_files = 0;
1454 int nr_subheaders = 0;
1455 struct ctl_table *entry;
1456
1457 /* special case: no directory and empty directory */
1458 if (!table || !table->procname)
1459 return 1;
1460
1461 list_for_each_table_entry(entry, table) {
1462 if (entry->child)
1463 nr_subheaders += count_subheaders(entry->child);
1464 else
1465 has_files = 1;
1466 }
1467 return nr_subheaders + has_files;
1468}
1469
1470static int register_leaf_sysctl_tables(const char *path, char *pos,
1471 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1472 struct ctl_table *table)
1473{
1474 struct ctl_table *ctl_table_arg = NULL;
1475 struct ctl_table *entry, *files;
1476 int nr_files = 0;
1477 int nr_dirs = 0;
1478 int err = -ENOMEM;
1479
1480 list_for_each_table_entry(entry, table) {
1481 if (entry->child)
1482 nr_dirs++;
1483 else
1484 nr_files++;
1485 }
1486
1487 files = table;
1488 /* If there are mixed files and directories we need a new table */
1489 if (nr_dirs && nr_files) {
1490 struct ctl_table *new;
1491 files = kcalloc(nr_files + 1, sizeof(struct ctl_table),
1492 GFP_KERNEL);
1493 if (!files)
1494 goto out;
1495
1496 ctl_table_arg = files;
1497 new = files;
1498
1499 list_for_each_table_entry(entry, table) {
1500 if (entry->child)
1501 continue;
1502 *new = *entry;
1503 new++;
1504 }
1505 }
1506
1507 /* Register everything except a directory full of subdirectories */
1508 if (nr_files || !nr_dirs) {
1509 struct ctl_table_header *header;
1510 header = __register_sysctl_table(set, path, files);
1511 if (!header) {
1512 kfree(ctl_table_arg);
1513 goto out;
1514 }
1515
1516 /* Remember if we need to free the file table */
1517 header->ctl_table_arg = ctl_table_arg;
1518 **subheader = header;
1519 (*subheader)++;
1520 }
1521
1522 /* Recurse into the subdirectories. */
1523 list_for_each_table_entry(entry, table) {
1524 char *child_pos;
1525
1526 if (!entry->child)
1527 continue;
1528
1529 err = -ENAMETOOLONG;
1530 child_pos = append_path(path, pos, entry->procname);
1531 if (!child_pos)
1532 goto out;
1533
1534 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1535 set, entry->child);
1536 pos[0] = '\0';
1537 if (err)
1538 goto out;
1539 }
1540 err = 0;
1541out:
1542 /* On failure our caller will unregister all registered subheaders */
1543 return err;
1544}
1545
1546/**
1547 * __register_sysctl_paths - register a sysctl table hierarchy
1548 * @set: Sysctl tree to register on
1549 * @path: The path to the directory the sysctl table is in.
1550 * @table: the top-level table structure
1551 *
1552 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1553 * array. A completely 0 filled entry terminates the table.
1554 *
1555 * See __register_sysctl_table for more details.
1556 */
1557struct ctl_table_header *__register_sysctl_paths(
1558 struct ctl_table_set *set,
1559 const struct ctl_path *path, struct ctl_table *table)
1560{
1561 struct ctl_table *ctl_table_arg = table;
1562 int nr_subheaders = count_subheaders(table);
1563 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1564 const struct ctl_path *component;
1565 char *new_path, *pos;
1566
1567 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1568 if (!new_path)
1569 return NULL;
1570
1571 pos[0] = '\0';
1572 for (component = path; component->procname; component++) {
1573 pos = append_path(new_path, pos, component->procname);
1574 if (!pos)
1575 goto out;
1576 }
1577 while (table->procname && table->child && !table[1].procname) {
1578 pos = append_path(new_path, pos, table->procname);
1579 if (!pos)
1580 goto out;
1581 table = table->child;
1582 }
1583 if (nr_subheaders == 1) {
1584 header = __register_sysctl_table(set, new_path, table);
1585 if (header)
1586 header->ctl_table_arg = ctl_table_arg;
1587 } else {
1588 header = kzalloc(sizeof(*header) +
1589 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1590 if (!header)
1591 goto out;
1592
1593 subheaders = (struct ctl_table_header **) (header + 1);
1594 subheader = subheaders;
1595 header->ctl_table_arg = ctl_table_arg;
1596
1597 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1598 set, table))
1599 goto err_register_leaves;
1600 }
1601
1602out:
1603 kfree(new_path);
1604 return header;
1605
1606err_register_leaves:
1607 while (subheader > subheaders) {
1608 struct ctl_table_header *subh = *(--subheader);
1609 struct ctl_table *table = subh->ctl_table_arg;
1610 unregister_sysctl_table(subh);
1611 kfree(table);
1612 }
1613 kfree(header);
1614 header = NULL;
1615 goto out;
1616}
1617
1618/**
1619 * register_sysctl_paths - register a sysctl table hierarchy
1620 * @path: The path to the directory the sysctl table is in.
1621 * @table: the top-level table structure
1622 *
1623 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1624 * array. A completely 0 filled entry terminates the table.
1625 *
1626 * See __register_sysctl_paths for more details.
1627 */
1628struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1629 struct ctl_table *table)
1630{
1631 return __register_sysctl_paths(&sysctl_table_root.default_set,
1632 path, table);
1633}
1634EXPORT_SYMBOL(register_sysctl_paths);
1635
1636/**
1637 * register_sysctl_table - register a sysctl table hierarchy
1638 * @table: the top-level table structure
1639 *
1640 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1641 * array. A completely 0 filled entry terminates the table.
1642 *
1643 * See register_sysctl_paths for more details.
1644 */
1645struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1646{
1647 static const struct ctl_path null_path[] = { {} };
1648
1649 return register_sysctl_paths(null_path, table);
1650}
1651EXPORT_SYMBOL(register_sysctl_table);
1652
1653int __register_sysctl_base(struct ctl_table *base_table)
1654{
1655 struct ctl_table_header *hdr;
1656
1657 hdr = register_sysctl_table(base_table);
1658 kmemleak_not_leak(hdr);
1659 return 0;
1660}
1661
1662static void put_links(struct ctl_table_header *header)
1663{
1664 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1665 struct ctl_table_root *root = header->root;
1666 struct ctl_dir *parent = header->parent;
1667 struct ctl_dir *core_parent;
1668 struct ctl_table *entry;
1669
1670 if (header->set == root_set)
1671 return;
1672
1673 core_parent = xlate_dir(root_set, parent);
1674 if (IS_ERR(core_parent))
1675 return;
1676
1677 list_for_each_table_entry(entry, header->ctl_table) {
1678 struct ctl_table_header *link_head;
1679 struct ctl_table *link;
1680 const char *name = entry->procname;
1681
1682 link = find_entry(&link_head, core_parent, name, strlen(name));
1683 if (link &&
1684 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1685 (S_ISLNK(link->mode) && (link->data == root)))) {
1686 drop_sysctl_table(link_head);
1687 }
1688 else {
1689 pr_err("sysctl link missing during unregister: ");
1690 sysctl_print_dir(parent);
1691 pr_cont("%s\n", name);
1692 }
1693 }
1694}
1695
1696static void drop_sysctl_table(struct ctl_table_header *header)
1697{
1698 struct ctl_dir *parent = header->parent;
1699
1700 if (--header->nreg)
1701 return;
1702
1703 if (parent) {
1704 put_links(header);
1705 start_unregistering(header);
1706 }
1707
1708 if (!--header->count)
1709 kfree_rcu(header, rcu);
1710
1711 if (parent)
1712 drop_sysctl_table(&parent->header);
1713}
1714
1715/**
1716 * unregister_sysctl_table - unregister a sysctl table hierarchy
1717 * @header: the header returned from register_sysctl_table
1718 *
1719 * Unregisters the sysctl table and all children. proc entries may not
1720 * actually be removed until they are no longer used by anyone.
1721 */
1722void unregister_sysctl_table(struct ctl_table_header * header)
1723{
1724 int nr_subheaders;
1725 might_sleep();
1726
1727 if (header == NULL)
1728 return;
1729
1730 nr_subheaders = count_subheaders(header->ctl_table_arg);
1731 if (unlikely(nr_subheaders > 1)) {
1732 struct ctl_table_header **subheaders;
1733 int i;
1734
1735 subheaders = (struct ctl_table_header **)(header + 1);
1736 for (i = nr_subheaders -1; i >= 0; i--) {
1737 struct ctl_table_header *subh = subheaders[i];
1738 struct ctl_table *table = subh->ctl_table_arg;
1739 unregister_sysctl_table(subh);
1740 kfree(table);
1741 }
1742 kfree(header);
1743 return;
1744 }
1745
1746 spin_lock(&sysctl_lock);
1747 drop_sysctl_table(header);
1748 spin_unlock(&sysctl_lock);
1749}
1750EXPORT_SYMBOL(unregister_sysctl_table);
1751
1752void setup_sysctl_set(struct ctl_table_set *set,
1753 struct ctl_table_root *root,
1754 int (*is_seen)(struct ctl_table_set *))
1755{
1756 memset(set, 0, sizeof(*set));
1757 set->is_seen = is_seen;
1758 init_header(&set->dir.header, root, set, NULL, root_table);
1759}
1760
1761void retire_sysctl_set(struct ctl_table_set *set)
1762{
1763 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1764}
1765
1766int __init proc_sys_init(void)
1767{
1768 struct proc_dir_entry *proc_sys_root;
1769
1770 proc_sys_root = proc_mkdir("sys", NULL);
1771 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1772 proc_sys_root->proc_dir_ops = &proc_sys_dir_file_operations;
1773 proc_sys_root->nlink = 0;
1774
1775 return sysctl_init_bases();
1776}
1777
1778struct sysctl_alias {
1779 const char *kernel_param;
1780 const char *sysctl_param;
1781};
1782
1783/*
1784 * Historically some settings had both sysctl and a command line parameter.
1785 * With the generic sysctl. parameter support, we can handle them at a single
1786 * place and only keep the historical name for compatibility. This is not meant
1787 * to add brand new aliases. When adding existing aliases, consider whether
1788 * the possibly different moment of changing the value (e.g. from early_param
1789 * to the moment do_sysctl_args() is called) is an issue for the specific
1790 * parameter.
1791 */
1792static const struct sysctl_alias sysctl_aliases[] = {
1793 {"hardlockup_all_cpu_backtrace", "kernel.hardlockup_all_cpu_backtrace" },
1794 {"hung_task_panic", "kernel.hung_task_panic" },
1795 {"numa_zonelist_order", "vm.numa_zonelist_order" },
1796 {"softlockup_all_cpu_backtrace", "kernel.softlockup_all_cpu_backtrace" },
1797 {"softlockup_panic", "kernel.softlockup_panic" },
1798 { }
1799};
1800
1801static const char *sysctl_find_alias(char *param)
1802{
1803 const struct sysctl_alias *alias;
1804
1805 for (alias = &sysctl_aliases[0]; alias->kernel_param != NULL; alias++) {
1806 if (strcmp(alias->kernel_param, param) == 0)
1807 return alias->sysctl_param;
1808 }
1809
1810 return NULL;
1811}
1812
1813/* Set sysctl value passed on kernel command line. */
1814static int process_sysctl_arg(char *param, char *val,
1815 const char *unused, void *arg)
1816{
1817 char *path;
1818 struct vfsmount **proc_mnt = arg;
1819 struct file_system_type *proc_fs_type;
1820 struct file *file;
1821 int len;
1822 int err;
1823 loff_t pos = 0;
1824 ssize_t wret;
1825
1826 if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {
1827 param += sizeof("sysctl") - 1;
1828
1829 if (param[0] != '/' && param[0] != '.')
1830 return 0;
1831
1832 param++;
1833 } else {
1834 param = (char *) sysctl_find_alias(param);
1835 if (!param)
1836 return 0;
1837 }
1838
1839 if (!val)
1840 return -EINVAL;
1841 len = strlen(val);
1842 if (len == 0)
1843 return -EINVAL;
1844
1845 /*
1846 * To set sysctl options, we use a temporary mount of proc, look up the
1847 * respective sys/ file and write to it. To avoid mounting it when no
1848 * options were given, we mount it only when the first sysctl option is
1849 * found. Why not a persistent mount? There are problems with a
1850 * persistent mount of proc in that it forces userspace not to use any
1851 * proc mount options.
1852 */
1853 if (!*proc_mnt) {
1854 proc_fs_type = get_fs_type("proc");
1855 if (!proc_fs_type) {
1856 pr_err("Failed to find procfs to set sysctl from command line\n");
1857 return 0;
1858 }
1859 *proc_mnt = kern_mount(proc_fs_type);
1860 put_filesystem(proc_fs_type);
1861 if (IS_ERR(*proc_mnt)) {
1862 pr_err("Failed to mount procfs to set sysctl from command line\n");
1863 return 0;
1864 }
1865 }
1866
1867 path = kasprintf(GFP_KERNEL, "sys/%s", param);
1868 if (!path)
1869 panic("%s: Failed to allocate path for %s\n", __func__, param);
1870 strreplace(path, '.', '/');
1871
1872 file = file_open_root_mnt(*proc_mnt, path, O_WRONLY, 0);
1873 if (IS_ERR(file)) {
1874 err = PTR_ERR(file);
1875 if (err == -ENOENT)
1876 pr_err("Failed to set sysctl parameter '%s=%s': parameter not found\n",
1877 param, val);
1878 else if (err == -EACCES)
1879 pr_err("Failed to set sysctl parameter '%s=%s': permission denied (read-only?)\n",
1880 param, val);
1881 else
1882 pr_err("Error %pe opening proc file to set sysctl parameter '%s=%s'\n",
1883 file, param, val);
1884 goto out;
1885 }
1886 wret = kernel_write(file, val, len, &pos);
1887 if (wret < 0) {
1888 err = wret;
1889 if (err == -EINVAL)
1890 pr_err("Failed to set sysctl parameter '%s=%s': invalid value\n",
1891 param, val);
1892 else
1893 pr_err("Error %pe writing to proc file to set sysctl parameter '%s=%s'\n",
1894 ERR_PTR(err), param, val);
1895 } else if (wret != len) {
1896 pr_err("Wrote only %zd bytes of %d writing to proc file %s to set sysctl parameter '%s=%s\n",
1897 wret, len, path, param, val);
1898 }
1899
1900 err = filp_close(file, NULL);
1901 if (err)
1902 pr_err("Error %pe closing proc file to set sysctl parameter '%s=%s\n",
1903 ERR_PTR(err), param, val);
1904out:
1905 kfree(path);
1906 return 0;
1907}
1908
1909void do_sysctl_args(void)
1910{
1911 char *command_line;
1912 struct vfsmount *proc_mnt = NULL;
1913
1914 command_line = kstrdup(saved_command_line, GFP_KERNEL);
1915 if (!command_line)
1916 panic("%s: Failed to allocate copy of command line\n", __func__);
1917
1918 parse_args("Setting sysctl args", command_line,
1919 NULL, 0, -1, -1, &proc_mnt, process_sysctl_arg);
1920
1921 if (proc_mnt)
1922 kern_unmount(proc_mnt);
1923
1924 kfree(command_line);
1925}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * /proc/sys support
4 */
5#include <linux/init.h>
6#include <linux/sysctl.h>
7#include <linux/poll.h>
8#include <linux/proc_fs.h>
9#include <linux/printk.h>
10#include <linux/security.h>
11#include <linux/sched.h>
12#include <linux/cred.h>
13#include <linux/namei.h>
14#include <linux/mm.h>
15#include <linux/module.h>
16#include "internal.h"
17
18static const struct dentry_operations proc_sys_dentry_operations;
19static const struct file_operations proc_sys_file_operations;
20static const struct inode_operations proc_sys_inode_operations;
21static const struct file_operations proc_sys_dir_file_operations;
22static const struct inode_operations proc_sys_dir_operations;
23
24/* Support for permanently empty directories */
25
26struct ctl_table sysctl_mount_point[] = {
27 { }
28};
29
30static bool is_empty_dir(struct ctl_table_header *head)
31{
32 return head->ctl_table[0].child == sysctl_mount_point;
33}
34
35static void set_empty_dir(struct ctl_dir *dir)
36{
37 dir->header.ctl_table[0].child = sysctl_mount_point;
38}
39
40static void clear_empty_dir(struct ctl_dir *dir)
41
42{
43 dir->header.ctl_table[0].child = NULL;
44}
45
46void proc_sys_poll_notify(struct ctl_table_poll *poll)
47{
48 if (!poll)
49 return;
50
51 atomic_inc(&poll->event);
52 wake_up_interruptible(&poll->wait);
53}
54
55static struct ctl_table root_table[] = {
56 {
57 .procname = "",
58 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
59 },
60 { }
61};
62static struct ctl_table_root sysctl_table_root = {
63 .default_set.dir.header = {
64 {{.count = 1,
65 .nreg = 1,
66 .ctl_table = root_table }},
67 .ctl_table_arg = root_table,
68 .root = &sysctl_table_root,
69 .set = &sysctl_table_root.default_set,
70 },
71};
72
73static DEFINE_SPINLOCK(sysctl_lock);
74
75static void drop_sysctl_table(struct ctl_table_header *header);
76static int sysctl_follow_link(struct ctl_table_header **phead,
77 struct ctl_table **pentry);
78static int insert_links(struct ctl_table_header *head);
79static void put_links(struct ctl_table_header *header);
80
81static void sysctl_print_dir(struct ctl_dir *dir)
82{
83 if (dir->header.parent)
84 sysctl_print_dir(dir->header.parent);
85 pr_cont("%s/", dir->header.ctl_table[0].procname);
86}
87
88static int namecmp(const char *name1, int len1, const char *name2, int len2)
89{
90 int minlen;
91 int cmp;
92
93 minlen = len1;
94 if (minlen > len2)
95 minlen = len2;
96
97 cmp = memcmp(name1, name2, minlen);
98 if (cmp == 0)
99 cmp = len1 - len2;
100 return cmp;
101}
102
103/* Called under sysctl_lock */
104static struct ctl_table *find_entry(struct ctl_table_header **phead,
105 struct ctl_dir *dir, const char *name, int namelen)
106{
107 struct ctl_table_header *head;
108 struct ctl_table *entry;
109 struct rb_node *node = dir->root.rb_node;
110
111 while (node)
112 {
113 struct ctl_node *ctl_node;
114 const char *procname;
115 int cmp;
116
117 ctl_node = rb_entry(node, struct ctl_node, node);
118 head = ctl_node->header;
119 entry = &head->ctl_table[ctl_node - head->node];
120 procname = entry->procname;
121
122 cmp = namecmp(name, namelen, procname, strlen(procname));
123 if (cmp < 0)
124 node = node->rb_left;
125 else if (cmp > 0)
126 node = node->rb_right;
127 else {
128 *phead = head;
129 return entry;
130 }
131 }
132 return NULL;
133}
134
135static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
136{
137 struct rb_node *node = &head->node[entry - head->ctl_table].node;
138 struct rb_node **p = &head->parent->root.rb_node;
139 struct rb_node *parent = NULL;
140 const char *name = entry->procname;
141 int namelen = strlen(name);
142
143 while (*p) {
144 struct ctl_table_header *parent_head;
145 struct ctl_table *parent_entry;
146 struct ctl_node *parent_node;
147 const char *parent_name;
148 int cmp;
149
150 parent = *p;
151 parent_node = rb_entry(parent, struct ctl_node, node);
152 parent_head = parent_node->header;
153 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
154 parent_name = parent_entry->procname;
155
156 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
157 if (cmp < 0)
158 p = &(*p)->rb_left;
159 else if (cmp > 0)
160 p = &(*p)->rb_right;
161 else {
162 pr_err("sysctl duplicate entry: ");
163 sysctl_print_dir(head->parent);
164 pr_cont("/%s\n", entry->procname);
165 return -EEXIST;
166 }
167 }
168
169 rb_link_node(node, parent, p);
170 rb_insert_color(node, &head->parent->root);
171 return 0;
172}
173
174static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
175{
176 struct rb_node *node = &head->node[entry - head->ctl_table].node;
177
178 rb_erase(node, &head->parent->root);
179}
180
181static void init_header(struct ctl_table_header *head,
182 struct ctl_table_root *root, struct ctl_table_set *set,
183 struct ctl_node *node, struct ctl_table *table)
184{
185 head->ctl_table = table;
186 head->ctl_table_arg = table;
187 head->used = 0;
188 head->count = 1;
189 head->nreg = 1;
190 head->unregistering = NULL;
191 head->root = root;
192 head->set = set;
193 head->parent = NULL;
194 head->node = node;
195 INIT_HLIST_HEAD(&head->inodes);
196 if (node) {
197 struct ctl_table *entry;
198 for (entry = table; entry->procname; entry++, node++)
199 node->header = head;
200 }
201}
202
203static void erase_header(struct ctl_table_header *head)
204{
205 struct ctl_table *entry;
206 for (entry = head->ctl_table; entry->procname; entry++)
207 erase_entry(head, entry);
208}
209
210static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
211{
212 struct ctl_table *entry;
213 int err;
214
215 /* Is this a permanently empty directory? */
216 if (is_empty_dir(&dir->header))
217 return -EROFS;
218
219 /* Am I creating a permanently empty directory? */
220 if (header->ctl_table == sysctl_mount_point) {
221 if (!RB_EMPTY_ROOT(&dir->root))
222 return -EINVAL;
223 set_empty_dir(dir);
224 }
225
226 dir->header.nreg++;
227 header->parent = dir;
228 err = insert_links(header);
229 if (err)
230 goto fail_links;
231 for (entry = header->ctl_table; entry->procname; entry++) {
232 err = insert_entry(header, entry);
233 if (err)
234 goto fail;
235 }
236 return 0;
237fail:
238 erase_header(header);
239 put_links(header);
240fail_links:
241 if (header->ctl_table == sysctl_mount_point)
242 clear_empty_dir(dir);
243 header->parent = NULL;
244 drop_sysctl_table(&dir->header);
245 return err;
246}
247
248/* called under sysctl_lock */
249static int use_table(struct ctl_table_header *p)
250{
251 if (unlikely(p->unregistering))
252 return 0;
253 p->used++;
254 return 1;
255}
256
257/* called under sysctl_lock */
258static void unuse_table(struct ctl_table_header *p)
259{
260 if (!--p->used)
261 if (unlikely(p->unregistering))
262 complete(p->unregistering);
263}
264
265static void proc_sys_prune_dcache(struct ctl_table_header *head)
266{
267 struct inode *inode;
268 struct proc_inode *ei;
269 struct hlist_node *node;
270 struct super_block *sb;
271
272 rcu_read_lock();
273 for (;;) {
274 node = hlist_first_rcu(&head->inodes);
275 if (!node)
276 break;
277 ei = hlist_entry(node, struct proc_inode, sysctl_inodes);
278 spin_lock(&sysctl_lock);
279 hlist_del_init_rcu(&ei->sysctl_inodes);
280 spin_unlock(&sysctl_lock);
281
282 inode = &ei->vfs_inode;
283 sb = inode->i_sb;
284 if (!atomic_inc_not_zero(&sb->s_active))
285 continue;
286 inode = igrab(inode);
287 rcu_read_unlock();
288 if (unlikely(!inode)) {
289 deactivate_super(sb);
290 rcu_read_lock();
291 continue;
292 }
293
294 d_prune_aliases(inode);
295 iput(inode);
296 deactivate_super(sb);
297
298 rcu_read_lock();
299 }
300 rcu_read_unlock();
301}
302
303/* called under sysctl_lock, will reacquire if has to wait */
304static void start_unregistering(struct ctl_table_header *p)
305{
306 /*
307 * if p->used is 0, nobody will ever touch that entry again;
308 * we'll eliminate all paths to it before dropping sysctl_lock
309 */
310 if (unlikely(p->used)) {
311 struct completion wait;
312 init_completion(&wait);
313 p->unregistering = &wait;
314 spin_unlock(&sysctl_lock);
315 wait_for_completion(&wait);
316 } else {
317 /* anything non-NULL; we'll never dereference it */
318 p->unregistering = ERR_PTR(-EINVAL);
319 spin_unlock(&sysctl_lock);
320 }
321 /*
322 * Prune dentries for unregistered sysctls: namespaced sysctls
323 * can have duplicate names and contaminate dcache very badly.
324 */
325 proc_sys_prune_dcache(p);
326 /*
327 * do not remove from the list until nobody holds it; walking the
328 * list in do_sysctl() relies on that.
329 */
330 spin_lock(&sysctl_lock);
331 erase_header(p);
332}
333
334static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
335{
336 BUG_ON(!head);
337 spin_lock(&sysctl_lock);
338 if (!use_table(head))
339 head = ERR_PTR(-ENOENT);
340 spin_unlock(&sysctl_lock);
341 return head;
342}
343
344static void sysctl_head_finish(struct ctl_table_header *head)
345{
346 if (!head)
347 return;
348 spin_lock(&sysctl_lock);
349 unuse_table(head);
350 spin_unlock(&sysctl_lock);
351}
352
353static struct ctl_table_set *
354lookup_header_set(struct ctl_table_root *root)
355{
356 struct ctl_table_set *set = &root->default_set;
357 if (root->lookup)
358 set = root->lookup(root);
359 return set;
360}
361
362static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
363 struct ctl_dir *dir,
364 const char *name, int namelen)
365{
366 struct ctl_table_header *head;
367 struct ctl_table *entry;
368
369 spin_lock(&sysctl_lock);
370 entry = find_entry(&head, dir, name, namelen);
371 if (entry && use_table(head))
372 *phead = head;
373 else
374 entry = NULL;
375 spin_unlock(&sysctl_lock);
376 return entry;
377}
378
379static struct ctl_node *first_usable_entry(struct rb_node *node)
380{
381 struct ctl_node *ctl_node;
382
383 for (;node; node = rb_next(node)) {
384 ctl_node = rb_entry(node, struct ctl_node, node);
385 if (use_table(ctl_node->header))
386 return ctl_node;
387 }
388 return NULL;
389}
390
391static void first_entry(struct ctl_dir *dir,
392 struct ctl_table_header **phead, struct ctl_table **pentry)
393{
394 struct ctl_table_header *head = NULL;
395 struct ctl_table *entry = NULL;
396 struct ctl_node *ctl_node;
397
398 spin_lock(&sysctl_lock);
399 ctl_node = first_usable_entry(rb_first(&dir->root));
400 spin_unlock(&sysctl_lock);
401 if (ctl_node) {
402 head = ctl_node->header;
403 entry = &head->ctl_table[ctl_node - head->node];
404 }
405 *phead = head;
406 *pentry = entry;
407}
408
409static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
410{
411 struct ctl_table_header *head = *phead;
412 struct ctl_table *entry = *pentry;
413 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
414
415 spin_lock(&sysctl_lock);
416 unuse_table(head);
417
418 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
419 spin_unlock(&sysctl_lock);
420 head = NULL;
421 if (ctl_node) {
422 head = ctl_node->header;
423 entry = &head->ctl_table[ctl_node - head->node];
424 }
425 *phead = head;
426 *pentry = entry;
427}
428
429/*
430 * sysctl_perm does NOT grant the superuser all rights automatically, because
431 * some sysctl variables are readonly even to root.
432 */
433
434static int test_perm(int mode, int op)
435{
436 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
437 mode >>= 6;
438 else if (in_egroup_p(GLOBAL_ROOT_GID))
439 mode >>= 3;
440 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
441 return 0;
442 return -EACCES;
443}
444
445static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
446{
447 struct ctl_table_root *root = head->root;
448 int mode;
449
450 if (root->permissions)
451 mode = root->permissions(head, table);
452 else
453 mode = table->mode;
454
455 return test_perm(mode, op);
456}
457
458static struct inode *proc_sys_make_inode(struct super_block *sb,
459 struct ctl_table_header *head, struct ctl_table *table)
460{
461 struct ctl_table_root *root = head->root;
462 struct inode *inode;
463 struct proc_inode *ei;
464
465 inode = new_inode(sb);
466 if (!inode)
467 goto out;
468
469 inode->i_ino = get_next_ino();
470
471 ei = PROC_I(inode);
472
473 spin_lock(&sysctl_lock);
474 if (unlikely(head->unregistering)) {
475 spin_unlock(&sysctl_lock);
476 iput(inode);
477 inode = NULL;
478 goto out;
479 }
480 ei->sysctl = head;
481 ei->sysctl_entry = table;
482 hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes);
483 head->count++;
484 spin_unlock(&sysctl_lock);
485
486 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
487 inode->i_mode = table->mode;
488 if (!S_ISDIR(table->mode)) {
489 inode->i_mode |= S_IFREG;
490 inode->i_op = &proc_sys_inode_operations;
491 inode->i_fop = &proc_sys_file_operations;
492 } else {
493 inode->i_mode |= S_IFDIR;
494 inode->i_op = &proc_sys_dir_operations;
495 inode->i_fop = &proc_sys_dir_file_operations;
496 if (is_empty_dir(head))
497 make_empty_dir_inode(inode);
498 }
499
500 if (root->set_ownership)
501 root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
502
503out:
504 return inode;
505}
506
507void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
508{
509 spin_lock(&sysctl_lock);
510 hlist_del_init_rcu(&PROC_I(inode)->sysctl_inodes);
511 if (!--head->count)
512 kfree_rcu(head, rcu);
513 spin_unlock(&sysctl_lock);
514}
515
516static struct ctl_table_header *grab_header(struct inode *inode)
517{
518 struct ctl_table_header *head = PROC_I(inode)->sysctl;
519 if (!head)
520 head = &sysctl_table_root.default_set.dir.header;
521 return sysctl_head_grab(head);
522}
523
524static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
525 unsigned int flags)
526{
527 struct ctl_table_header *head = grab_header(dir);
528 struct ctl_table_header *h = NULL;
529 const struct qstr *name = &dentry->d_name;
530 struct ctl_table *p;
531 struct inode *inode;
532 struct dentry *err = ERR_PTR(-ENOENT);
533 struct ctl_dir *ctl_dir;
534 int ret;
535
536 if (IS_ERR(head))
537 return ERR_CAST(head);
538
539 ctl_dir = container_of(head, struct ctl_dir, header);
540
541 p = lookup_entry(&h, ctl_dir, name->name, name->len);
542 if (!p)
543 goto out;
544
545 if (S_ISLNK(p->mode)) {
546 ret = sysctl_follow_link(&h, &p);
547 err = ERR_PTR(ret);
548 if (ret)
549 goto out;
550 }
551
552 err = ERR_PTR(-ENOMEM);
553 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
554 if (!inode)
555 goto out;
556
557 err = NULL;
558 d_set_d_op(dentry, &proc_sys_dentry_operations);
559 d_add(dentry, inode);
560
561out:
562 if (h)
563 sysctl_head_finish(h);
564 sysctl_head_finish(head);
565 return err;
566}
567
568static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
569 size_t count, loff_t *ppos, int write)
570{
571 struct inode *inode = file_inode(filp);
572 struct ctl_table_header *head = grab_header(inode);
573 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
574 ssize_t error;
575 size_t res;
576
577 if (IS_ERR(head))
578 return PTR_ERR(head);
579
580 /*
581 * At this point we know that the sysctl was not unregistered
582 * and won't be until we finish.
583 */
584 error = -EPERM;
585 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
586 goto out;
587
588 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
589 error = -EINVAL;
590 if (!table->proc_handler)
591 goto out;
592
593 /* careful: calling conventions are nasty here */
594 res = count;
595 error = table->proc_handler(table, write, buf, &res, ppos);
596 if (!error)
597 error = res;
598out:
599 sysctl_head_finish(head);
600
601 return error;
602}
603
604static ssize_t proc_sys_read(struct file *filp, char __user *buf,
605 size_t count, loff_t *ppos)
606{
607 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
608}
609
610static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
611 size_t count, loff_t *ppos)
612{
613 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
614}
615
616static int proc_sys_open(struct inode *inode, struct file *filp)
617{
618 struct ctl_table_header *head = grab_header(inode);
619 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
620
621 /* sysctl was unregistered */
622 if (IS_ERR(head))
623 return PTR_ERR(head);
624
625 if (table->poll)
626 filp->private_data = proc_sys_poll_event(table->poll);
627
628 sysctl_head_finish(head);
629
630 return 0;
631}
632
633static __poll_t proc_sys_poll(struct file *filp, poll_table *wait)
634{
635 struct inode *inode = file_inode(filp);
636 struct ctl_table_header *head = grab_header(inode);
637 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
638 __poll_t ret = DEFAULT_POLLMASK;
639 unsigned long event;
640
641 /* sysctl was unregistered */
642 if (IS_ERR(head))
643 return EPOLLERR | EPOLLHUP;
644
645 if (!table->proc_handler)
646 goto out;
647
648 if (!table->poll)
649 goto out;
650
651 event = (unsigned long)filp->private_data;
652 poll_wait(filp, &table->poll->wait, wait);
653
654 if (event != atomic_read(&table->poll->event)) {
655 filp->private_data = proc_sys_poll_event(table->poll);
656 ret = EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI;
657 }
658
659out:
660 sysctl_head_finish(head);
661
662 return ret;
663}
664
665static bool proc_sys_fill_cache(struct file *file,
666 struct dir_context *ctx,
667 struct ctl_table_header *head,
668 struct ctl_table *table)
669{
670 struct dentry *child, *dir = file->f_path.dentry;
671 struct inode *inode;
672 struct qstr qname;
673 ino_t ino = 0;
674 unsigned type = DT_UNKNOWN;
675
676 qname.name = table->procname;
677 qname.len = strlen(table->procname);
678 qname.hash = full_name_hash(dir, qname.name, qname.len);
679
680 child = d_lookup(dir, &qname);
681 if (!child) {
682 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
683 child = d_alloc_parallel(dir, &qname, &wq);
684 if (IS_ERR(child))
685 return false;
686 if (d_in_lookup(child)) {
687 inode = proc_sys_make_inode(dir->d_sb, head, table);
688 if (!inode) {
689 d_lookup_done(child);
690 dput(child);
691 return false;
692 }
693 d_set_d_op(child, &proc_sys_dentry_operations);
694 d_add(child, inode);
695 }
696 }
697 inode = d_inode(child);
698 ino = inode->i_ino;
699 type = inode->i_mode >> 12;
700 dput(child);
701 return dir_emit(ctx, qname.name, qname.len, ino, type);
702}
703
704static bool proc_sys_link_fill_cache(struct file *file,
705 struct dir_context *ctx,
706 struct ctl_table_header *head,
707 struct ctl_table *table)
708{
709 bool ret = true;
710
711 head = sysctl_head_grab(head);
712 if (IS_ERR(head))
713 return false;
714
715 /* It is not an error if we can not follow the link ignore it */
716 if (sysctl_follow_link(&head, &table))
717 goto out;
718
719 ret = proc_sys_fill_cache(file, ctx, head, table);
720out:
721 sysctl_head_finish(head);
722 return ret;
723}
724
725static int scan(struct ctl_table_header *head, struct ctl_table *table,
726 unsigned long *pos, struct file *file,
727 struct dir_context *ctx)
728{
729 bool res;
730
731 if ((*pos)++ < ctx->pos)
732 return true;
733
734 if (unlikely(S_ISLNK(table->mode)))
735 res = proc_sys_link_fill_cache(file, ctx, head, table);
736 else
737 res = proc_sys_fill_cache(file, ctx, head, table);
738
739 if (res)
740 ctx->pos = *pos;
741
742 return res;
743}
744
745static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
746{
747 struct ctl_table_header *head = grab_header(file_inode(file));
748 struct ctl_table_header *h = NULL;
749 struct ctl_table *entry;
750 struct ctl_dir *ctl_dir;
751 unsigned long pos;
752
753 if (IS_ERR(head))
754 return PTR_ERR(head);
755
756 ctl_dir = container_of(head, struct ctl_dir, header);
757
758 if (!dir_emit_dots(file, ctx))
759 goto out;
760
761 pos = 2;
762
763 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
764 if (!scan(h, entry, &pos, file, ctx)) {
765 sysctl_head_finish(h);
766 break;
767 }
768 }
769out:
770 sysctl_head_finish(head);
771 return 0;
772}
773
774static int proc_sys_permission(struct inode *inode, int mask)
775{
776 /*
777 * sysctl entries that are not writeable,
778 * are _NOT_ writeable, capabilities or not.
779 */
780 struct ctl_table_header *head;
781 struct ctl_table *table;
782 int error;
783
784 /* Executable files are not allowed under /proc/sys/ */
785 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
786 return -EACCES;
787
788 head = grab_header(inode);
789 if (IS_ERR(head))
790 return PTR_ERR(head);
791
792 table = PROC_I(inode)->sysctl_entry;
793 if (!table) /* global root - r-xr-xr-x */
794 error = mask & MAY_WRITE ? -EACCES : 0;
795 else /* Use the permissions on the sysctl table entry */
796 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
797
798 sysctl_head_finish(head);
799 return error;
800}
801
802static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
803{
804 struct inode *inode = d_inode(dentry);
805 int error;
806
807 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
808 return -EPERM;
809
810 error = setattr_prepare(dentry, attr);
811 if (error)
812 return error;
813
814 setattr_copy(inode, attr);
815 mark_inode_dirty(inode);
816 return 0;
817}
818
819static int proc_sys_getattr(const struct path *path, struct kstat *stat,
820 u32 request_mask, unsigned int query_flags)
821{
822 struct inode *inode = d_inode(path->dentry);
823 struct ctl_table_header *head = grab_header(inode);
824 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
825
826 if (IS_ERR(head))
827 return PTR_ERR(head);
828
829 generic_fillattr(inode, stat);
830 if (table)
831 stat->mode = (stat->mode & S_IFMT) | table->mode;
832
833 sysctl_head_finish(head);
834 return 0;
835}
836
837static const struct file_operations proc_sys_file_operations = {
838 .open = proc_sys_open,
839 .poll = proc_sys_poll,
840 .read = proc_sys_read,
841 .write = proc_sys_write,
842 .llseek = default_llseek,
843};
844
845static const struct file_operations proc_sys_dir_file_operations = {
846 .read = generic_read_dir,
847 .iterate_shared = proc_sys_readdir,
848 .llseek = generic_file_llseek,
849};
850
851static const struct inode_operations proc_sys_inode_operations = {
852 .permission = proc_sys_permission,
853 .setattr = proc_sys_setattr,
854 .getattr = proc_sys_getattr,
855};
856
857static const struct inode_operations proc_sys_dir_operations = {
858 .lookup = proc_sys_lookup,
859 .permission = proc_sys_permission,
860 .setattr = proc_sys_setattr,
861 .getattr = proc_sys_getattr,
862};
863
864static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
865{
866 if (flags & LOOKUP_RCU)
867 return -ECHILD;
868 return !PROC_I(d_inode(dentry))->sysctl->unregistering;
869}
870
871static int proc_sys_delete(const struct dentry *dentry)
872{
873 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
874}
875
876static int sysctl_is_seen(struct ctl_table_header *p)
877{
878 struct ctl_table_set *set = p->set;
879 int res;
880 spin_lock(&sysctl_lock);
881 if (p->unregistering)
882 res = 0;
883 else if (!set->is_seen)
884 res = 1;
885 else
886 res = set->is_seen(set);
887 spin_unlock(&sysctl_lock);
888 return res;
889}
890
891static int proc_sys_compare(const struct dentry *dentry,
892 unsigned int len, const char *str, const struct qstr *name)
893{
894 struct ctl_table_header *head;
895 struct inode *inode;
896
897 /* Although proc doesn't have negative dentries, rcu-walk means
898 * that inode here can be NULL */
899 /* AV: can it, indeed? */
900 inode = d_inode_rcu(dentry);
901 if (!inode)
902 return 1;
903 if (name->len != len)
904 return 1;
905 if (memcmp(name->name, str, len))
906 return 1;
907 head = rcu_dereference(PROC_I(inode)->sysctl);
908 return !head || !sysctl_is_seen(head);
909}
910
911static const struct dentry_operations proc_sys_dentry_operations = {
912 .d_revalidate = proc_sys_revalidate,
913 .d_delete = proc_sys_delete,
914 .d_compare = proc_sys_compare,
915};
916
917static struct ctl_dir *find_subdir(struct ctl_dir *dir,
918 const char *name, int namelen)
919{
920 struct ctl_table_header *head;
921 struct ctl_table *entry;
922
923 entry = find_entry(&head, dir, name, namelen);
924 if (!entry)
925 return ERR_PTR(-ENOENT);
926 if (!S_ISDIR(entry->mode))
927 return ERR_PTR(-ENOTDIR);
928 return container_of(head, struct ctl_dir, header);
929}
930
931static struct ctl_dir *new_dir(struct ctl_table_set *set,
932 const char *name, int namelen)
933{
934 struct ctl_table *table;
935 struct ctl_dir *new;
936 struct ctl_node *node;
937 char *new_name;
938
939 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
940 sizeof(struct ctl_table)*2 + namelen + 1,
941 GFP_KERNEL);
942 if (!new)
943 return NULL;
944
945 node = (struct ctl_node *)(new + 1);
946 table = (struct ctl_table *)(node + 1);
947 new_name = (char *)(table + 2);
948 memcpy(new_name, name, namelen);
949 new_name[namelen] = '\0';
950 table[0].procname = new_name;
951 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
952 init_header(&new->header, set->dir.header.root, set, node, table);
953
954 return new;
955}
956
957/**
958 * get_subdir - find or create a subdir with the specified name.
959 * @dir: Directory to create the subdirectory in
960 * @name: The name of the subdirectory to find or create
961 * @namelen: The length of name
962 *
963 * Takes a directory with an elevated reference count so we know that
964 * if we drop the lock the directory will not go away. Upon success
965 * the reference is moved from @dir to the returned subdirectory.
966 * Upon error an error code is returned and the reference on @dir is
967 * simply dropped.
968 */
969static struct ctl_dir *get_subdir(struct ctl_dir *dir,
970 const char *name, int namelen)
971{
972 struct ctl_table_set *set = dir->header.set;
973 struct ctl_dir *subdir, *new = NULL;
974 int err;
975
976 spin_lock(&sysctl_lock);
977 subdir = find_subdir(dir, name, namelen);
978 if (!IS_ERR(subdir))
979 goto found;
980 if (PTR_ERR(subdir) != -ENOENT)
981 goto failed;
982
983 spin_unlock(&sysctl_lock);
984 new = new_dir(set, name, namelen);
985 spin_lock(&sysctl_lock);
986 subdir = ERR_PTR(-ENOMEM);
987 if (!new)
988 goto failed;
989
990 /* Was the subdir added while we dropped the lock? */
991 subdir = find_subdir(dir, name, namelen);
992 if (!IS_ERR(subdir))
993 goto found;
994 if (PTR_ERR(subdir) != -ENOENT)
995 goto failed;
996
997 /* Nope. Use the our freshly made directory entry. */
998 err = insert_header(dir, &new->header);
999 subdir = ERR_PTR(err);
1000 if (err)
1001 goto failed;
1002 subdir = new;
1003found:
1004 subdir->header.nreg++;
1005failed:
1006 if (IS_ERR(subdir)) {
1007 pr_err("sysctl could not get directory: ");
1008 sysctl_print_dir(dir);
1009 pr_cont("/%*.*s %ld\n",
1010 namelen, namelen, name, PTR_ERR(subdir));
1011 }
1012 drop_sysctl_table(&dir->header);
1013 if (new)
1014 drop_sysctl_table(&new->header);
1015 spin_unlock(&sysctl_lock);
1016 return subdir;
1017}
1018
1019static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
1020{
1021 struct ctl_dir *parent;
1022 const char *procname;
1023 if (!dir->header.parent)
1024 return &set->dir;
1025 parent = xlate_dir(set, dir->header.parent);
1026 if (IS_ERR(parent))
1027 return parent;
1028 procname = dir->header.ctl_table[0].procname;
1029 return find_subdir(parent, procname, strlen(procname));
1030}
1031
1032static int sysctl_follow_link(struct ctl_table_header **phead,
1033 struct ctl_table **pentry)
1034{
1035 struct ctl_table_header *head;
1036 struct ctl_table_root *root;
1037 struct ctl_table_set *set;
1038 struct ctl_table *entry;
1039 struct ctl_dir *dir;
1040 int ret;
1041
1042 ret = 0;
1043 spin_lock(&sysctl_lock);
1044 root = (*pentry)->data;
1045 set = lookup_header_set(root);
1046 dir = xlate_dir(set, (*phead)->parent);
1047 if (IS_ERR(dir))
1048 ret = PTR_ERR(dir);
1049 else {
1050 const char *procname = (*pentry)->procname;
1051 head = NULL;
1052 entry = find_entry(&head, dir, procname, strlen(procname));
1053 ret = -ENOENT;
1054 if (entry && use_table(head)) {
1055 unuse_table(*phead);
1056 *phead = head;
1057 *pentry = entry;
1058 ret = 0;
1059 }
1060 }
1061
1062 spin_unlock(&sysctl_lock);
1063 return ret;
1064}
1065
1066static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
1067{
1068 struct va_format vaf;
1069 va_list args;
1070
1071 va_start(args, fmt);
1072 vaf.fmt = fmt;
1073 vaf.va = &args;
1074
1075 pr_err("sysctl table check failed: %s/%s %pV\n",
1076 path, table->procname, &vaf);
1077
1078 va_end(args);
1079 return -EINVAL;
1080}
1081
1082static int sysctl_check_table_array(const char *path, struct ctl_table *table)
1083{
1084 int err = 0;
1085
1086 if ((table->proc_handler == proc_douintvec) ||
1087 (table->proc_handler == proc_douintvec_minmax)) {
1088 if (table->maxlen != sizeof(unsigned int))
1089 err |= sysctl_err(path, table, "array not allowed");
1090 }
1091
1092 return err;
1093}
1094
1095static int sysctl_check_table(const char *path, struct ctl_table *table)
1096{
1097 int err = 0;
1098 for (; table->procname; table++) {
1099 if (table->child)
1100 err |= sysctl_err(path, table, "Not a file");
1101
1102 if ((table->proc_handler == proc_dostring) ||
1103 (table->proc_handler == proc_dointvec) ||
1104 (table->proc_handler == proc_douintvec) ||
1105 (table->proc_handler == proc_douintvec_minmax) ||
1106 (table->proc_handler == proc_dointvec_minmax) ||
1107 (table->proc_handler == proc_dointvec_jiffies) ||
1108 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1109 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1110 (table->proc_handler == proc_doulongvec_minmax) ||
1111 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1112 if (!table->data)
1113 err |= sysctl_err(path, table, "No data");
1114 if (!table->maxlen)
1115 err |= sysctl_err(path, table, "No maxlen");
1116 else
1117 err |= sysctl_check_table_array(path, table);
1118 }
1119 if (!table->proc_handler)
1120 err |= sysctl_err(path, table, "No proc_handler");
1121
1122 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1123 err |= sysctl_err(path, table, "bogus .mode 0%o",
1124 table->mode);
1125 }
1126 return err;
1127}
1128
1129static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1130 struct ctl_table_root *link_root)
1131{
1132 struct ctl_table *link_table, *entry, *link;
1133 struct ctl_table_header *links;
1134 struct ctl_node *node;
1135 char *link_name;
1136 int nr_entries, name_bytes;
1137
1138 name_bytes = 0;
1139 nr_entries = 0;
1140 for (entry = table; entry->procname; entry++) {
1141 nr_entries++;
1142 name_bytes += strlen(entry->procname) + 1;
1143 }
1144
1145 links = kzalloc(sizeof(struct ctl_table_header) +
1146 sizeof(struct ctl_node)*nr_entries +
1147 sizeof(struct ctl_table)*(nr_entries + 1) +
1148 name_bytes,
1149 GFP_KERNEL);
1150
1151 if (!links)
1152 return NULL;
1153
1154 node = (struct ctl_node *)(links + 1);
1155 link_table = (struct ctl_table *)(node + nr_entries);
1156 link_name = (char *)&link_table[nr_entries + 1];
1157
1158 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1159 int len = strlen(entry->procname) + 1;
1160 memcpy(link_name, entry->procname, len);
1161 link->procname = link_name;
1162 link->mode = S_IFLNK|S_IRWXUGO;
1163 link->data = link_root;
1164 link_name += len;
1165 }
1166 init_header(links, dir->header.root, dir->header.set, node, link_table);
1167 links->nreg = nr_entries;
1168
1169 return links;
1170}
1171
1172static bool get_links(struct ctl_dir *dir,
1173 struct ctl_table *table, struct ctl_table_root *link_root)
1174{
1175 struct ctl_table_header *head;
1176 struct ctl_table *entry, *link;
1177
1178 /* Are there links available for every entry in table? */
1179 for (entry = table; entry->procname; entry++) {
1180 const char *procname = entry->procname;
1181 link = find_entry(&head, dir, procname, strlen(procname));
1182 if (!link)
1183 return false;
1184 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1185 continue;
1186 if (S_ISLNK(link->mode) && (link->data == link_root))
1187 continue;
1188 return false;
1189 }
1190
1191 /* The checks passed. Increase the registration count on the links */
1192 for (entry = table; entry->procname; entry++) {
1193 const char *procname = entry->procname;
1194 link = find_entry(&head, dir, procname, strlen(procname));
1195 head->nreg++;
1196 }
1197 return true;
1198}
1199
1200static int insert_links(struct ctl_table_header *head)
1201{
1202 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1203 struct ctl_dir *core_parent = NULL;
1204 struct ctl_table_header *links;
1205 int err;
1206
1207 if (head->set == root_set)
1208 return 0;
1209
1210 core_parent = xlate_dir(root_set, head->parent);
1211 if (IS_ERR(core_parent))
1212 return 0;
1213
1214 if (get_links(core_parent, head->ctl_table, head->root))
1215 return 0;
1216
1217 core_parent->header.nreg++;
1218 spin_unlock(&sysctl_lock);
1219
1220 links = new_links(core_parent, head->ctl_table, head->root);
1221
1222 spin_lock(&sysctl_lock);
1223 err = -ENOMEM;
1224 if (!links)
1225 goto out;
1226
1227 err = 0;
1228 if (get_links(core_parent, head->ctl_table, head->root)) {
1229 kfree(links);
1230 goto out;
1231 }
1232
1233 err = insert_header(core_parent, links);
1234 if (err)
1235 kfree(links);
1236out:
1237 drop_sysctl_table(&core_parent->header);
1238 return err;
1239}
1240
1241/**
1242 * __register_sysctl_table - register a leaf sysctl table
1243 * @set: Sysctl tree to register on
1244 * @path: The path to the directory the sysctl table is in.
1245 * @table: the top-level table structure
1246 *
1247 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1248 * array. A completely 0 filled entry terminates the table.
1249 *
1250 * The members of the &struct ctl_table structure are used as follows:
1251 *
1252 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1253 * enter a sysctl file
1254 *
1255 * data - a pointer to data for use by proc_handler
1256 *
1257 * maxlen - the maximum size in bytes of the data
1258 *
1259 * mode - the file permissions for the /proc/sys file
1260 *
1261 * child - must be %NULL.
1262 *
1263 * proc_handler - the text handler routine (described below)
1264 *
1265 * extra1, extra2 - extra pointers usable by the proc handler routines
1266 *
1267 * Leaf nodes in the sysctl tree will be represented by a single file
1268 * under /proc; non-leaf nodes will be represented by directories.
1269 *
1270 * There must be a proc_handler routine for any terminal nodes.
1271 * Several default handlers are available to cover common cases -
1272 *
1273 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1274 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1275 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1276 *
1277 * It is the handler's job to read the input buffer from user memory
1278 * and process it. The handler should return 0 on success.
1279 *
1280 * This routine returns %NULL on a failure to register, and a pointer
1281 * to the table header on success.
1282 */
1283struct ctl_table_header *__register_sysctl_table(
1284 struct ctl_table_set *set,
1285 const char *path, struct ctl_table *table)
1286{
1287 struct ctl_table_root *root = set->dir.header.root;
1288 struct ctl_table_header *header;
1289 const char *name, *nextname;
1290 struct ctl_dir *dir;
1291 struct ctl_table *entry;
1292 struct ctl_node *node;
1293 int nr_entries = 0;
1294
1295 for (entry = table; entry->procname; entry++)
1296 nr_entries++;
1297
1298 header = kzalloc(sizeof(struct ctl_table_header) +
1299 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1300 if (!header)
1301 return NULL;
1302
1303 node = (struct ctl_node *)(header + 1);
1304 init_header(header, root, set, node, table);
1305 if (sysctl_check_table(path, table))
1306 goto fail;
1307
1308 spin_lock(&sysctl_lock);
1309 dir = &set->dir;
1310 /* Reference moved down the diretory tree get_subdir */
1311 dir->header.nreg++;
1312 spin_unlock(&sysctl_lock);
1313
1314 /* Find the directory for the ctl_table */
1315 for (name = path; name; name = nextname) {
1316 int namelen;
1317 nextname = strchr(name, '/');
1318 if (nextname) {
1319 namelen = nextname - name;
1320 nextname++;
1321 } else {
1322 namelen = strlen(name);
1323 }
1324 if (namelen == 0)
1325 continue;
1326
1327 dir = get_subdir(dir, name, namelen);
1328 if (IS_ERR(dir))
1329 goto fail;
1330 }
1331
1332 spin_lock(&sysctl_lock);
1333 if (insert_header(dir, header))
1334 goto fail_put_dir_locked;
1335
1336 drop_sysctl_table(&dir->header);
1337 spin_unlock(&sysctl_lock);
1338
1339 return header;
1340
1341fail_put_dir_locked:
1342 drop_sysctl_table(&dir->header);
1343 spin_unlock(&sysctl_lock);
1344fail:
1345 kfree(header);
1346 dump_stack();
1347 return NULL;
1348}
1349
1350/**
1351 * register_sysctl - register a sysctl table
1352 * @path: The path to the directory the sysctl table is in.
1353 * @table: the table structure
1354 *
1355 * Register a sysctl table. @table should be a filled in ctl_table
1356 * array. A completely 0 filled entry terminates the table.
1357 *
1358 * See __register_sysctl_table for more details.
1359 */
1360struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1361{
1362 return __register_sysctl_table(&sysctl_table_root.default_set,
1363 path, table);
1364}
1365EXPORT_SYMBOL(register_sysctl);
1366
1367static char *append_path(const char *path, char *pos, const char *name)
1368{
1369 int namelen;
1370 namelen = strlen(name);
1371 if (((pos - path) + namelen + 2) >= PATH_MAX)
1372 return NULL;
1373 memcpy(pos, name, namelen);
1374 pos[namelen] = '/';
1375 pos[namelen + 1] = '\0';
1376 pos += namelen + 1;
1377 return pos;
1378}
1379
1380static int count_subheaders(struct ctl_table *table)
1381{
1382 int has_files = 0;
1383 int nr_subheaders = 0;
1384 struct ctl_table *entry;
1385
1386 /* special case: no directory and empty directory */
1387 if (!table || !table->procname)
1388 return 1;
1389
1390 for (entry = table; entry->procname; entry++) {
1391 if (entry->child)
1392 nr_subheaders += count_subheaders(entry->child);
1393 else
1394 has_files = 1;
1395 }
1396 return nr_subheaders + has_files;
1397}
1398
1399static int register_leaf_sysctl_tables(const char *path, char *pos,
1400 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1401 struct ctl_table *table)
1402{
1403 struct ctl_table *ctl_table_arg = NULL;
1404 struct ctl_table *entry, *files;
1405 int nr_files = 0;
1406 int nr_dirs = 0;
1407 int err = -ENOMEM;
1408
1409 for (entry = table; entry->procname; entry++) {
1410 if (entry->child)
1411 nr_dirs++;
1412 else
1413 nr_files++;
1414 }
1415
1416 files = table;
1417 /* If there are mixed files and directories we need a new table */
1418 if (nr_dirs && nr_files) {
1419 struct ctl_table *new;
1420 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1421 GFP_KERNEL);
1422 if (!files)
1423 goto out;
1424
1425 ctl_table_arg = files;
1426 for (new = files, entry = table; entry->procname; entry++) {
1427 if (entry->child)
1428 continue;
1429 *new = *entry;
1430 new++;
1431 }
1432 }
1433
1434 /* Register everything except a directory full of subdirectories */
1435 if (nr_files || !nr_dirs) {
1436 struct ctl_table_header *header;
1437 header = __register_sysctl_table(set, path, files);
1438 if (!header) {
1439 kfree(ctl_table_arg);
1440 goto out;
1441 }
1442
1443 /* Remember if we need to free the file table */
1444 header->ctl_table_arg = ctl_table_arg;
1445 **subheader = header;
1446 (*subheader)++;
1447 }
1448
1449 /* Recurse into the subdirectories. */
1450 for (entry = table; entry->procname; entry++) {
1451 char *child_pos;
1452
1453 if (!entry->child)
1454 continue;
1455
1456 err = -ENAMETOOLONG;
1457 child_pos = append_path(path, pos, entry->procname);
1458 if (!child_pos)
1459 goto out;
1460
1461 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1462 set, entry->child);
1463 pos[0] = '\0';
1464 if (err)
1465 goto out;
1466 }
1467 err = 0;
1468out:
1469 /* On failure our caller will unregister all registered subheaders */
1470 return err;
1471}
1472
1473/**
1474 * __register_sysctl_paths - register a sysctl table hierarchy
1475 * @set: Sysctl tree to register on
1476 * @path: The path to the directory the sysctl table is in.
1477 * @table: the top-level table structure
1478 *
1479 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1480 * array. A completely 0 filled entry terminates the table.
1481 *
1482 * See __register_sysctl_table for more details.
1483 */
1484struct ctl_table_header *__register_sysctl_paths(
1485 struct ctl_table_set *set,
1486 const struct ctl_path *path, struct ctl_table *table)
1487{
1488 struct ctl_table *ctl_table_arg = table;
1489 int nr_subheaders = count_subheaders(table);
1490 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1491 const struct ctl_path *component;
1492 char *new_path, *pos;
1493
1494 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1495 if (!new_path)
1496 return NULL;
1497
1498 pos[0] = '\0';
1499 for (component = path; component->procname; component++) {
1500 pos = append_path(new_path, pos, component->procname);
1501 if (!pos)
1502 goto out;
1503 }
1504 while (table->procname && table->child && !table[1].procname) {
1505 pos = append_path(new_path, pos, table->procname);
1506 if (!pos)
1507 goto out;
1508 table = table->child;
1509 }
1510 if (nr_subheaders == 1) {
1511 header = __register_sysctl_table(set, new_path, table);
1512 if (header)
1513 header->ctl_table_arg = ctl_table_arg;
1514 } else {
1515 header = kzalloc(sizeof(*header) +
1516 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1517 if (!header)
1518 goto out;
1519
1520 subheaders = (struct ctl_table_header **) (header + 1);
1521 subheader = subheaders;
1522 header->ctl_table_arg = ctl_table_arg;
1523
1524 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1525 set, table))
1526 goto err_register_leaves;
1527 }
1528
1529out:
1530 kfree(new_path);
1531 return header;
1532
1533err_register_leaves:
1534 while (subheader > subheaders) {
1535 struct ctl_table_header *subh = *(--subheader);
1536 struct ctl_table *table = subh->ctl_table_arg;
1537 unregister_sysctl_table(subh);
1538 kfree(table);
1539 }
1540 kfree(header);
1541 header = NULL;
1542 goto out;
1543}
1544
1545/**
1546 * register_sysctl_table_path - register a sysctl table hierarchy
1547 * @path: The path to the directory the sysctl table is in.
1548 * @table: the top-level table structure
1549 *
1550 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1551 * array. A completely 0 filled entry terminates the table.
1552 *
1553 * See __register_sysctl_paths for more details.
1554 */
1555struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1556 struct ctl_table *table)
1557{
1558 return __register_sysctl_paths(&sysctl_table_root.default_set,
1559 path, table);
1560}
1561EXPORT_SYMBOL(register_sysctl_paths);
1562
1563/**
1564 * register_sysctl_table - register a sysctl table hierarchy
1565 * @table: the top-level table structure
1566 *
1567 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1568 * array. A completely 0 filled entry terminates the table.
1569 *
1570 * See register_sysctl_paths for more details.
1571 */
1572struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1573{
1574 static const struct ctl_path null_path[] = { {} };
1575
1576 return register_sysctl_paths(null_path, table);
1577}
1578EXPORT_SYMBOL(register_sysctl_table);
1579
1580static void put_links(struct ctl_table_header *header)
1581{
1582 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1583 struct ctl_table_root *root = header->root;
1584 struct ctl_dir *parent = header->parent;
1585 struct ctl_dir *core_parent;
1586 struct ctl_table *entry;
1587
1588 if (header->set == root_set)
1589 return;
1590
1591 core_parent = xlate_dir(root_set, parent);
1592 if (IS_ERR(core_parent))
1593 return;
1594
1595 for (entry = header->ctl_table; entry->procname; entry++) {
1596 struct ctl_table_header *link_head;
1597 struct ctl_table *link;
1598 const char *name = entry->procname;
1599
1600 link = find_entry(&link_head, core_parent, name, strlen(name));
1601 if (link &&
1602 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1603 (S_ISLNK(link->mode) && (link->data == root)))) {
1604 drop_sysctl_table(link_head);
1605 }
1606 else {
1607 pr_err("sysctl link missing during unregister: ");
1608 sysctl_print_dir(parent);
1609 pr_cont("/%s\n", name);
1610 }
1611 }
1612}
1613
1614static void drop_sysctl_table(struct ctl_table_header *header)
1615{
1616 struct ctl_dir *parent = header->parent;
1617
1618 if (--header->nreg)
1619 return;
1620
1621 put_links(header);
1622 start_unregistering(header);
1623 if (!--header->count)
1624 kfree_rcu(header, rcu);
1625
1626 if (parent)
1627 drop_sysctl_table(&parent->header);
1628}
1629
1630/**
1631 * unregister_sysctl_table - unregister a sysctl table hierarchy
1632 * @header: the header returned from register_sysctl_table
1633 *
1634 * Unregisters the sysctl table and all children. proc entries may not
1635 * actually be removed until they are no longer used by anyone.
1636 */
1637void unregister_sysctl_table(struct ctl_table_header * header)
1638{
1639 int nr_subheaders;
1640 might_sleep();
1641
1642 if (header == NULL)
1643 return;
1644
1645 nr_subheaders = count_subheaders(header->ctl_table_arg);
1646 if (unlikely(nr_subheaders > 1)) {
1647 struct ctl_table_header **subheaders;
1648 int i;
1649
1650 subheaders = (struct ctl_table_header **)(header + 1);
1651 for (i = nr_subheaders -1; i >= 0; i--) {
1652 struct ctl_table_header *subh = subheaders[i];
1653 struct ctl_table *table = subh->ctl_table_arg;
1654 unregister_sysctl_table(subh);
1655 kfree(table);
1656 }
1657 kfree(header);
1658 return;
1659 }
1660
1661 spin_lock(&sysctl_lock);
1662 drop_sysctl_table(header);
1663 spin_unlock(&sysctl_lock);
1664}
1665EXPORT_SYMBOL(unregister_sysctl_table);
1666
1667void setup_sysctl_set(struct ctl_table_set *set,
1668 struct ctl_table_root *root,
1669 int (*is_seen)(struct ctl_table_set *))
1670{
1671 memset(set, 0, sizeof(*set));
1672 set->is_seen = is_seen;
1673 init_header(&set->dir.header, root, set, NULL, root_table);
1674}
1675
1676void retire_sysctl_set(struct ctl_table_set *set)
1677{
1678 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1679}
1680
1681int __init proc_sys_init(void)
1682{
1683 struct proc_dir_entry *proc_sys_root;
1684
1685 proc_sys_root = proc_mkdir("sys", NULL);
1686 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1687 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1688 proc_sys_root->nlink = 0;
1689
1690 return sysctl_init();
1691}