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