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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/security.h>
9#include <linux/sched.h>
10#include <linux/namei.h>
11#include <linux/mm.h>
12#include <linux/module.h>
13#include "internal.h"
14
15static const struct dentry_operations proc_sys_dentry_operations;
16static const struct file_operations proc_sys_file_operations;
17static const struct inode_operations proc_sys_inode_operations;
18static const struct file_operations proc_sys_dir_file_operations;
19static const struct inode_operations proc_sys_dir_operations;
20
21void proc_sys_poll_notify(struct ctl_table_poll *poll)
22{
23 if (!poll)
24 return;
25
26 atomic_inc(&poll->event);
27 wake_up_interruptible(&poll->wait);
28}
29
30static struct ctl_table root_table[] = {
31 {
32 .procname = "",
33 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
34 },
35 { }
36};
37static struct ctl_table_root sysctl_table_root = {
38 .default_set.dir.header = {
39 {{.count = 1,
40 .nreg = 1,
41 .ctl_table = root_table }},
42 .ctl_table_arg = root_table,
43 .root = &sysctl_table_root,
44 .set = &sysctl_table_root.default_set,
45 },
46};
47
48static DEFINE_SPINLOCK(sysctl_lock);
49
50static void drop_sysctl_table(struct ctl_table_header *header);
51static int sysctl_follow_link(struct ctl_table_header **phead,
52 struct ctl_table **pentry, struct nsproxy *namespaces);
53static int insert_links(struct ctl_table_header *head);
54static void put_links(struct ctl_table_header *header);
55
56static void sysctl_print_dir(struct ctl_dir *dir)
57{
58 if (dir->header.parent)
59 sysctl_print_dir(dir->header.parent);
60 printk(KERN_CONT "%s/", dir->header.ctl_table[0].procname);
61}
62
63static int namecmp(const char *name1, int len1, const char *name2, int len2)
64{
65 int minlen;
66 int cmp;
67
68 minlen = len1;
69 if (minlen > len2)
70 minlen = len2;
71
72 cmp = memcmp(name1, name2, minlen);
73 if (cmp == 0)
74 cmp = len1 - len2;
75 return cmp;
76}
77
78/* Called under sysctl_lock */
79static struct ctl_table *find_entry(struct ctl_table_header **phead,
80 struct ctl_dir *dir, const char *name, int namelen)
81{
82 struct ctl_table_header *head;
83 struct ctl_table *entry;
84 struct rb_node *node = dir->root.rb_node;
85
86 while (node)
87 {
88 struct ctl_node *ctl_node;
89 const char *procname;
90 int cmp;
91
92 ctl_node = rb_entry(node, struct ctl_node, node);
93 head = ctl_node->header;
94 entry = &head->ctl_table[ctl_node - head->node];
95 procname = entry->procname;
96
97 cmp = namecmp(name, namelen, procname, strlen(procname));
98 if (cmp < 0)
99 node = node->rb_left;
100 else if (cmp > 0)
101 node = node->rb_right;
102 else {
103 *phead = head;
104 return entry;
105 }
106 }
107 return NULL;
108}
109
110static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
111{
112 struct rb_node *node = &head->node[entry - head->ctl_table].node;
113 struct rb_node **p = &head->parent->root.rb_node;
114 struct rb_node *parent = NULL;
115 const char *name = entry->procname;
116 int namelen = strlen(name);
117
118 while (*p) {
119 struct ctl_table_header *parent_head;
120 struct ctl_table *parent_entry;
121 struct ctl_node *parent_node;
122 const char *parent_name;
123 int cmp;
124
125 parent = *p;
126 parent_node = rb_entry(parent, struct ctl_node, node);
127 parent_head = parent_node->header;
128 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
129 parent_name = parent_entry->procname;
130
131 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
132 if (cmp < 0)
133 p = &(*p)->rb_left;
134 else if (cmp > 0)
135 p = &(*p)->rb_right;
136 else {
137 printk(KERN_ERR "sysctl duplicate entry: ");
138 sysctl_print_dir(head->parent);
139 printk(KERN_CONT "/%s\n", entry->procname);
140 return -EEXIST;
141 }
142 }
143
144 rb_link_node(node, parent, p);
145 return 0;
146}
147
148static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
149{
150 struct rb_node *node = &head->node[entry - head->ctl_table].node;
151
152 rb_erase(node, &head->parent->root);
153}
154
155static void init_header(struct ctl_table_header *head,
156 struct ctl_table_root *root, struct ctl_table_set *set,
157 struct ctl_node *node, struct ctl_table *table)
158{
159 head->ctl_table = table;
160 head->ctl_table_arg = table;
161 head->used = 0;
162 head->count = 1;
163 head->nreg = 1;
164 head->unregistering = NULL;
165 head->root = root;
166 head->set = set;
167 head->parent = NULL;
168 head->node = node;
169 if (node) {
170 struct ctl_table *entry;
171 for (entry = table; entry->procname; entry++, node++) {
172 rb_init_node(&node->node);
173 node->header = head;
174 }
175 }
176}
177
178static void erase_header(struct ctl_table_header *head)
179{
180 struct ctl_table *entry;
181 for (entry = head->ctl_table; entry->procname; entry++)
182 erase_entry(head, entry);
183}
184
185static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
186{
187 struct ctl_table *entry;
188 int err;
189
190 dir->header.nreg++;
191 header->parent = dir;
192 err = insert_links(header);
193 if (err)
194 goto fail_links;
195 for (entry = header->ctl_table; entry->procname; entry++) {
196 err = insert_entry(header, entry);
197 if (err)
198 goto fail;
199 }
200 return 0;
201fail:
202 erase_header(header);
203 put_links(header);
204fail_links:
205 header->parent = NULL;
206 drop_sysctl_table(&dir->header);
207 return err;
208}
209
210/* called under sysctl_lock */
211static int use_table(struct ctl_table_header *p)
212{
213 if (unlikely(p->unregistering))
214 return 0;
215 p->used++;
216 return 1;
217}
218
219/* called under sysctl_lock */
220static void unuse_table(struct ctl_table_header *p)
221{
222 if (!--p->used)
223 if (unlikely(p->unregistering))
224 complete(p->unregistering);
225}
226
227/* called under sysctl_lock, will reacquire if has to wait */
228static void start_unregistering(struct ctl_table_header *p)
229{
230 /*
231 * if p->used is 0, nobody will ever touch that entry again;
232 * we'll eliminate all paths to it before dropping sysctl_lock
233 */
234 if (unlikely(p->used)) {
235 struct completion wait;
236 init_completion(&wait);
237 p->unregistering = &wait;
238 spin_unlock(&sysctl_lock);
239 wait_for_completion(&wait);
240 spin_lock(&sysctl_lock);
241 } else {
242 /* anything non-NULL; we'll never dereference it */
243 p->unregistering = ERR_PTR(-EINVAL);
244 }
245 /*
246 * do not remove from the list until nobody holds it; walking the
247 * list in do_sysctl() relies on that.
248 */
249 erase_header(p);
250}
251
252static void sysctl_head_get(struct ctl_table_header *head)
253{
254 spin_lock(&sysctl_lock);
255 head->count++;
256 spin_unlock(&sysctl_lock);
257}
258
259void sysctl_head_put(struct ctl_table_header *head)
260{
261 spin_lock(&sysctl_lock);
262 if (!--head->count)
263 kfree_rcu(head, rcu);
264 spin_unlock(&sysctl_lock);
265}
266
267static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
268{
269 if (!head)
270 BUG();
271 spin_lock(&sysctl_lock);
272 if (!use_table(head))
273 head = ERR_PTR(-ENOENT);
274 spin_unlock(&sysctl_lock);
275 return head;
276}
277
278static void sysctl_head_finish(struct ctl_table_header *head)
279{
280 if (!head)
281 return;
282 spin_lock(&sysctl_lock);
283 unuse_table(head);
284 spin_unlock(&sysctl_lock);
285}
286
287static struct ctl_table_set *
288lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces)
289{
290 struct ctl_table_set *set = &root->default_set;
291 if (root->lookup)
292 set = root->lookup(root, namespaces);
293 return set;
294}
295
296static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
297 struct ctl_dir *dir,
298 const char *name, int namelen)
299{
300 struct ctl_table_header *head;
301 struct ctl_table *entry;
302
303 spin_lock(&sysctl_lock);
304 entry = find_entry(&head, dir, name, namelen);
305 if (entry && use_table(head))
306 *phead = head;
307 else
308 entry = NULL;
309 spin_unlock(&sysctl_lock);
310 return entry;
311}
312
313static struct ctl_node *first_usable_entry(struct rb_node *node)
314{
315 struct ctl_node *ctl_node;
316
317 for (;node; node = rb_next(node)) {
318 ctl_node = rb_entry(node, struct ctl_node, node);
319 if (use_table(ctl_node->header))
320 return ctl_node;
321 }
322 return NULL;
323}
324
325static void first_entry(struct ctl_dir *dir,
326 struct ctl_table_header **phead, struct ctl_table **pentry)
327{
328 struct ctl_table_header *head = NULL;
329 struct ctl_table *entry = NULL;
330 struct ctl_node *ctl_node;
331
332 spin_lock(&sysctl_lock);
333 ctl_node = first_usable_entry(rb_first(&dir->root));
334 spin_unlock(&sysctl_lock);
335 if (ctl_node) {
336 head = ctl_node->header;
337 entry = &head->ctl_table[ctl_node - head->node];
338 }
339 *phead = head;
340 *pentry = entry;
341}
342
343static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
344{
345 struct ctl_table_header *head = *phead;
346 struct ctl_table *entry = *pentry;
347 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
348
349 spin_lock(&sysctl_lock);
350 unuse_table(head);
351
352 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
353 spin_unlock(&sysctl_lock);
354 head = NULL;
355 if (ctl_node) {
356 head = ctl_node->header;
357 entry = &head->ctl_table[ctl_node - head->node];
358 }
359 *phead = head;
360 *pentry = entry;
361}
362
363void register_sysctl_root(struct ctl_table_root *root)
364{
365}
366
367/*
368 * sysctl_perm does NOT grant the superuser all rights automatically, because
369 * some sysctl variables are readonly even to root.
370 */
371
372static int test_perm(int mode, int op)
373{
374 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
375 mode >>= 6;
376 else if (in_egroup_p(GLOBAL_ROOT_GID))
377 mode >>= 3;
378 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
379 return 0;
380 return -EACCES;
381}
382
383static int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op)
384{
385 int mode;
386
387 if (root->permissions)
388 mode = root->permissions(root, current->nsproxy, table);
389 else
390 mode = table->mode;
391
392 return test_perm(mode, op);
393}
394
395static struct inode *proc_sys_make_inode(struct super_block *sb,
396 struct ctl_table_header *head, struct ctl_table *table)
397{
398 struct inode *inode;
399 struct proc_inode *ei;
400
401 inode = new_inode(sb);
402 if (!inode)
403 goto out;
404
405 inode->i_ino = get_next_ino();
406
407 sysctl_head_get(head);
408 ei = PROC_I(inode);
409 ei->sysctl = head;
410 ei->sysctl_entry = table;
411
412 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
413 inode->i_mode = table->mode;
414 if (!S_ISDIR(table->mode)) {
415 inode->i_mode |= S_IFREG;
416 inode->i_op = &proc_sys_inode_operations;
417 inode->i_fop = &proc_sys_file_operations;
418 } else {
419 inode->i_mode |= S_IFDIR;
420 inode->i_op = &proc_sys_dir_operations;
421 inode->i_fop = &proc_sys_dir_file_operations;
422 }
423out:
424 return inode;
425}
426
427static struct ctl_table_header *grab_header(struct inode *inode)
428{
429 struct ctl_table_header *head = PROC_I(inode)->sysctl;
430 if (!head)
431 head = &sysctl_table_root.default_set.dir.header;
432 return sysctl_head_grab(head);
433}
434
435static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
436 struct nameidata *nd)
437{
438 struct ctl_table_header *head = grab_header(dir);
439 struct ctl_table_header *h = NULL;
440 struct qstr *name = &dentry->d_name;
441 struct ctl_table *p;
442 struct inode *inode;
443 struct dentry *err = ERR_PTR(-ENOENT);
444 struct ctl_dir *ctl_dir;
445 int ret;
446
447 if (IS_ERR(head))
448 return ERR_CAST(head);
449
450 ctl_dir = container_of(head, struct ctl_dir, header);
451
452 p = lookup_entry(&h, ctl_dir, name->name, name->len);
453 if (!p)
454 goto out;
455
456 if (S_ISLNK(p->mode)) {
457 ret = sysctl_follow_link(&h, &p, current->nsproxy);
458 err = ERR_PTR(ret);
459 if (ret)
460 goto out;
461 }
462
463 err = ERR_PTR(-ENOMEM);
464 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
465 if (!inode)
466 goto out;
467
468 err = NULL;
469 d_set_d_op(dentry, &proc_sys_dentry_operations);
470 d_add(dentry, inode);
471
472out:
473 if (h)
474 sysctl_head_finish(h);
475 sysctl_head_finish(head);
476 return err;
477}
478
479static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
480 size_t count, loff_t *ppos, int write)
481{
482 struct inode *inode = filp->f_path.dentry->d_inode;
483 struct ctl_table_header *head = grab_header(inode);
484 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
485 ssize_t error;
486 size_t res;
487
488 if (IS_ERR(head))
489 return PTR_ERR(head);
490
491 /*
492 * At this point we know that the sysctl was not unregistered
493 * and won't be until we finish.
494 */
495 error = -EPERM;
496 if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
497 goto out;
498
499 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
500 error = -EINVAL;
501 if (!table->proc_handler)
502 goto out;
503
504 /* careful: calling conventions are nasty here */
505 res = count;
506 error = table->proc_handler(table, write, buf, &res, ppos);
507 if (!error)
508 error = res;
509out:
510 sysctl_head_finish(head);
511
512 return error;
513}
514
515static ssize_t proc_sys_read(struct file *filp, char __user *buf,
516 size_t count, loff_t *ppos)
517{
518 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
519}
520
521static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
522 size_t count, loff_t *ppos)
523{
524 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
525}
526
527static int proc_sys_open(struct inode *inode, struct file *filp)
528{
529 struct ctl_table_header *head = grab_header(inode);
530 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
531
532 /* sysctl was unregistered */
533 if (IS_ERR(head))
534 return PTR_ERR(head);
535
536 if (table->poll)
537 filp->private_data = proc_sys_poll_event(table->poll);
538
539 sysctl_head_finish(head);
540
541 return 0;
542}
543
544static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
545{
546 struct inode *inode = filp->f_path.dentry->d_inode;
547 struct ctl_table_header *head = grab_header(inode);
548 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
549 unsigned int ret = DEFAULT_POLLMASK;
550 unsigned long event;
551
552 /* sysctl was unregistered */
553 if (IS_ERR(head))
554 return POLLERR | POLLHUP;
555
556 if (!table->proc_handler)
557 goto out;
558
559 if (!table->poll)
560 goto out;
561
562 event = (unsigned long)filp->private_data;
563 poll_wait(filp, &table->poll->wait, wait);
564
565 if (event != atomic_read(&table->poll->event)) {
566 filp->private_data = proc_sys_poll_event(table->poll);
567 ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI;
568 }
569
570out:
571 sysctl_head_finish(head);
572
573 return ret;
574}
575
576static int proc_sys_fill_cache(struct file *filp, void *dirent,
577 filldir_t filldir,
578 struct ctl_table_header *head,
579 struct ctl_table *table)
580{
581 struct dentry *child, *dir = filp->f_path.dentry;
582 struct inode *inode;
583 struct qstr qname;
584 ino_t ino = 0;
585 unsigned type = DT_UNKNOWN;
586
587 qname.name = table->procname;
588 qname.len = strlen(table->procname);
589 qname.hash = full_name_hash(qname.name, qname.len);
590
591 child = d_lookup(dir, &qname);
592 if (!child) {
593 child = d_alloc(dir, &qname);
594 if (child) {
595 inode = proc_sys_make_inode(dir->d_sb, head, table);
596 if (!inode) {
597 dput(child);
598 return -ENOMEM;
599 } else {
600 d_set_d_op(child, &proc_sys_dentry_operations);
601 d_add(child, inode);
602 }
603 } else {
604 return -ENOMEM;
605 }
606 }
607 inode = child->d_inode;
608 ino = inode->i_ino;
609 type = inode->i_mode >> 12;
610 dput(child);
611 return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
612}
613
614static int proc_sys_link_fill_cache(struct file *filp, void *dirent,
615 filldir_t filldir,
616 struct ctl_table_header *head,
617 struct ctl_table *table)
618{
619 int err, ret = 0;
620 head = sysctl_head_grab(head);
621
622 if (S_ISLNK(table->mode)) {
623 /* It is not an error if we can not follow the link ignore it */
624 err = sysctl_follow_link(&head, &table, current->nsproxy);
625 if (err)
626 goto out;
627 }
628
629 ret = proc_sys_fill_cache(filp, dirent, filldir, head, table);
630out:
631 sysctl_head_finish(head);
632 return ret;
633}
634
635static int scan(struct ctl_table_header *head, ctl_table *table,
636 unsigned long *pos, struct file *file,
637 void *dirent, filldir_t filldir)
638{
639 int res;
640
641 if ((*pos)++ < file->f_pos)
642 return 0;
643
644 if (unlikely(S_ISLNK(table->mode)))
645 res = proc_sys_link_fill_cache(file, dirent, filldir, head, table);
646 else
647 res = proc_sys_fill_cache(file, dirent, filldir, head, table);
648
649 if (res == 0)
650 file->f_pos = *pos;
651
652 return res;
653}
654
655static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
656{
657 struct dentry *dentry = filp->f_path.dentry;
658 struct inode *inode = dentry->d_inode;
659 struct ctl_table_header *head = grab_header(inode);
660 struct ctl_table_header *h = NULL;
661 struct ctl_table *entry;
662 struct ctl_dir *ctl_dir;
663 unsigned long pos;
664 int ret = -EINVAL;
665
666 if (IS_ERR(head))
667 return PTR_ERR(head);
668
669 ctl_dir = container_of(head, struct ctl_dir, header);
670
671 ret = 0;
672 /* Avoid a switch here: arm builds fail with missing __cmpdi2 */
673 if (filp->f_pos == 0) {
674 if (filldir(dirent, ".", 1, filp->f_pos,
675 inode->i_ino, DT_DIR) < 0)
676 goto out;
677 filp->f_pos++;
678 }
679 if (filp->f_pos == 1) {
680 if (filldir(dirent, "..", 2, filp->f_pos,
681 parent_ino(dentry), DT_DIR) < 0)
682 goto out;
683 filp->f_pos++;
684 }
685 pos = 2;
686
687 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
688 ret = scan(h, entry, &pos, filp, dirent, filldir);
689 if (ret) {
690 sysctl_head_finish(h);
691 break;
692 }
693 }
694 ret = 1;
695out:
696 sysctl_head_finish(head);
697 return ret;
698}
699
700static int proc_sys_permission(struct inode *inode, int mask)
701{
702 /*
703 * sysctl entries that are not writeable,
704 * are _NOT_ writeable, capabilities or not.
705 */
706 struct ctl_table_header *head;
707 struct ctl_table *table;
708 int error;
709
710 /* Executable files are not allowed under /proc/sys/ */
711 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
712 return -EACCES;
713
714 head = grab_header(inode);
715 if (IS_ERR(head))
716 return PTR_ERR(head);
717
718 table = PROC_I(inode)->sysctl_entry;
719 if (!table) /* global root - r-xr-xr-x */
720 error = mask & MAY_WRITE ? -EACCES : 0;
721 else /* Use the permissions on the sysctl table entry */
722 error = sysctl_perm(head->root, table, mask & ~MAY_NOT_BLOCK);
723
724 sysctl_head_finish(head);
725 return error;
726}
727
728static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
729{
730 struct inode *inode = dentry->d_inode;
731 int error;
732
733 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
734 return -EPERM;
735
736 error = inode_change_ok(inode, attr);
737 if (error)
738 return error;
739
740 if ((attr->ia_valid & ATTR_SIZE) &&
741 attr->ia_size != i_size_read(inode)) {
742 error = vmtruncate(inode, attr->ia_size);
743 if (error)
744 return error;
745 }
746
747 setattr_copy(inode, attr);
748 mark_inode_dirty(inode);
749 return 0;
750}
751
752static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
753{
754 struct inode *inode = dentry->d_inode;
755 struct ctl_table_header *head = grab_header(inode);
756 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
757
758 if (IS_ERR(head))
759 return PTR_ERR(head);
760
761 generic_fillattr(inode, stat);
762 if (table)
763 stat->mode = (stat->mode & S_IFMT) | table->mode;
764
765 sysctl_head_finish(head);
766 return 0;
767}
768
769static const struct file_operations proc_sys_file_operations = {
770 .open = proc_sys_open,
771 .poll = proc_sys_poll,
772 .read = proc_sys_read,
773 .write = proc_sys_write,
774 .llseek = default_llseek,
775};
776
777static const struct file_operations proc_sys_dir_file_operations = {
778 .read = generic_read_dir,
779 .readdir = proc_sys_readdir,
780 .llseek = generic_file_llseek,
781};
782
783static const struct inode_operations proc_sys_inode_operations = {
784 .permission = proc_sys_permission,
785 .setattr = proc_sys_setattr,
786 .getattr = proc_sys_getattr,
787};
788
789static const struct inode_operations proc_sys_dir_operations = {
790 .lookup = proc_sys_lookup,
791 .permission = proc_sys_permission,
792 .setattr = proc_sys_setattr,
793 .getattr = proc_sys_getattr,
794};
795
796static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
797{
798 if (nd->flags & LOOKUP_RCU)
799 return -ECHILD;
800 return !PROC_I(dentry->d_inode)->sysctl->unregistering;
801}
802
803static int proc_sys_delete(const struct dentry *dentry)
804{
805 return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
806}
807
808static int sysctl_is_seen(struct ctl_table_header *p)
809{
810 struct ctl_table_set *set = p->set;
811 int res;
812 spin_lock(&sysctl_lock);
813 if (p->unregistering)
814 res = 0;
815 else if (!set->is_seen)
816 res = 1;
817 else
818 res = set->is_seen(set);
819 spin_unlock(&sysctl_lock);
820 return res;
821}
822
823static int proc_sys_compare(const struct dentry *parent,
824 const struct inode *pinode,
825 const struct dentry *dentry, const struct inode *inode,
826 unsigned int len, const char *str, const struct qstr *name)
827{
828 struct ctl_table_header *head;
829 /* Although proc doesn't have negative dentries, rcu-walk means
830 * that inode here can be NULL */
831 /* AV: can it, indeed? */
832 if (!inode)
833 return 1;
834 if (name->len != len)
835 return 1;
836 if (memcmp(name->name, str, len))
837 return 1;
838 head = rcu_dereference(PROC_I(inode)->sysctl);
839 return !head || !sysctl_is_seen(head);
840}
841
842static const struct dentry_operations proc_sys_dentry_operations = {
843 .d_revalidate = proc_sys_revalidate,
844 .d_delete = proc_sys_delete,
845 .d_compare = proc_sys_compare,
846};
847
848static struct ctl_dir *find_subdir(struct ctl_dir *dir,
849 const char *name, int namelen)
850{
851 struct ctl_table_header *head;
852 struct ctl_table *entry;
853
854 entry = find_entry(&head, dir, name, namelen);
855 if (!entry)
856 return ERR_PTR(-ENOENT);
857 if (!S_ISDIR(entry->mode))
858 return ERR_PTR(-ENOTDIR);
859 return container_of(head, struct ctl_dir, header);
860}
861
862static struct ctl_dir *new_dir(struct ctl_table_set *set,
863 const char *name, int namelen)
864{
865 struct ctl_table *table;
866 struct ctl_dir *new;
867 struct ctl_node *node;
868 char *new_name;
869
870 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
871 sizeof(struct ctl_table)*2 + namelen + 1,
872 GFP_KERNEL);
873 if (!new)
874 return NULL;
875
876 node = (struct ctl_node *)(new + 1);
877 table = (struct ctl_table *)(node + 1);
878 new_name = (char *)(table + 2);
879 memcpy(new_name, name, namelen);
880 new_name[namelen] = '\0';
881 table[0].procname = new_name;
882 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
883 init_header(&new->header, set->dir.header.root, set, node, table);
884
885 return new;
886}
887
888/**
889 * get_subdir - find or create a subdir with the specified name.
890 * @dir: Directory to create the subdirectory in
891 * @name: The name of the subdirectory to find or create
892 * @namelen: The length of name
893 *
894 * Takes a directory with an elevated reference count so we know that
895 * if we drop the lock the directory will not go away. Upon success
896 * the reference is moved from @dir to the returned subdirectory.
897 * Upon error an error code is returned and the reference on @dir is
898 * simply dropped.
899 */
900static struct ctl_dir *get_subdir(struct ctl_dir *dir,
901 const char *name, int namelen)
902{
903 struct ctl_table_set *set = dir->header.set;
904 struct ctl_dir *subdir, *new = NULL;
905 int err;
906
907 spin_lock(&sysctl_lock);
908 subdir = find_subdir(dir, name, namelen);
909 if (!IS_ERR(subdir))
910 goto found;
911 if (PTR_ERR(subdir) != -ENOENT)
912 goto failed;
913
914 spin_unlock(&sysctl_lock);
915 new = new_dir(set, name, namelen);
916 spin_lock(&sysctl_lock);
917 subdir = ERR_PTR(-ENOMEM);
918 if (!new)
919 goto failed;
920
921 /* Was the subdir added while we dropped the lock? */
922 subdir = find_subdir(dir, name, namelen);
923 if (!IS_ERR(subdir))
924 goto found;
925 if (PTR_ERR(subdir) != -ENOENT)
926 goto failed;
927
928 /* Nope. Use the our freshly made directory entry. */
929 err = insert_header(dir, &new->header);
930 subdir = ERR_PTR(err);
931 if (err)
932 goto failed;
933 subdir = new;
934found:
935 subdir->header.nreg++;
936failed:
937 if (unlikely(IS_ERR(subdir))) {
938 printk(KERN_ERR "sysctl could not get directory: ");
939 sysctl_print_dir(dir);
940 printk(KERN_CONT "/%*.*s %ld\n",
941 namelen, namelen, name, PTR_ERR(subdir));
942 }
943 drop_sysctl_table(&dir->header);
944 if (new)
945 drop_sysctl_table(&new->header);
946 spin_unlock(&sysctl_lock);
947 return subdir;
948}
949
950static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
951{
952 struct ctl_dir *parent;
953 const char *procname;
954 if (!dir->header.parent)
955 return &set->dir;
956 parent = xlate_dir(set, dir->header.parent);
957 if (IS_ERR(parent))
958 return parent;
959 procname = dir->header.ctl_table[0].procname;
960 return find_subdir(parent, procname, strlen(procname));
961}
962
963static int sysctl_follow_link(struct ctl_table_header **phead,
964 struct ctl_table **pentry, struct nsproxy *namespaces)
965{
966 struct ctl_table_header *head;
967 struct ctl_table_root *root;
968 struct ctl_table_set *set;
969 struct ctl_table *entry;
970 struct ctl_dir *dir;
971 int ret;
972
973 ret = 0;
974 spin_lock(&sysctl_lock);
975 root = (*pentry)->data;
976 set = lookup_header_set(root, namespaces);
977 dir = xlate_dir(set, (*phead)->parent);
978 if (IS_ERR(dir))
979 ret = PTR_ERR(dir);
980 else {
981 const char *procname = (*pentry)->procname;
982 head = NULL;
983 entry = find_entry(&head, dir, procname, strlen(procname));
984 ret = -ENOENT;
985 if (entry && use_table(head)) {
986 unuse_table(*phead);
987 *phead = head;
988 *pentry = entry;
989 ret = 0;
990 }
991 }
992
993 spin_unlock(&sysctl_lock);
994 return ret;
995}
996
997static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
998{
999 struct va_format vaf;
1000 va_list args;
1001
1002 va_start(args, fmt);
1003 vaf.fmt = fmt;
1004 vaf.va = &args;
1005
1006 printk(KERN_ERR "sysctl table check failed: %s/%s %pV\n",
1007 path, table->procname, &vaf);
1008
1009 va_end(args);
1010 return -EINVAL;
1011}
1012
1013static int sysctl_check_table(const char *path, struct ctl_table *table)
1014{
1015 int err = 0;
1016 for (; table->procname; table++) {
1017 if (table->child)
1018 err = sysctl_err(path, table, "Not a file");
1019
1020 if ((table->proc_handler == proc_dostring) ||
1021 (table->proc_handler == proc_dointvec) ||
1022 (table->proc_handler == proc_dointvec_minmax) ||
1023 (table->proc_handler == proc_dointvec_jiffies) ||
1024 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1025 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1026 (table->proc_handler == proc_doulongvec_minmax) ||
1027 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1028 if (!table->data)
1029 err = sysctl_err(path, table, "No data");
1030 if (!table->maxlen)
1031 err = sysctl_err(path, table, "No maxlen");
1032 }
1033 if (!table->proc_handler)
1034 err = sysctl_err(path, table, "No proc_handler");
1035
1036 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1037 err = sysctl_err(path, table, "bogus .mode 0%o",
1038 table->mode);
1039 }
1040 return err;
1041}
1042
1043static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1044 struct ctl_table_root *link_root)
1045{
1046 struct ctl_table *link_table, *entry, *link;
1047 struct ctl_table_header *links;
1048 struct ctl_node *node;
1049 char *link_name;
1050 int nr_entries, name_bytes;
1051
1052 name_bytes = 0;
1053 nr_entries = 0;
1054 for (entry = table; entry->procname; entry++) {
1055 nr_entries++;
1056 name_bytes += strlen(entry->procname) + 1;
1057 }
1058
1059 links = kzalloc(sizeof(struct ctl_table_header) +
1060 sizeof(struct ctl_node)*nr_entries +
1061 sizeof(struct ctl_table)*(nr_entries + 1) +
1062 name_bytes,
1063 GFP_KERNEL);
1064
1065 if (!links)
1066 return NULL;
1067
1068 node = (struct ctl_node *)(links + 1);
1069 link_table = (struct ctl_table *)(node + nr_entries);
1070 link_name = (char *)&link_table[nr_entries + 1];
1071
1072 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1073 int len = strlen(entry->procname) + 1;
1074 memcpy(link_name, entry->procname, len);
1075 link->procname = link_name;
1076 link->mode = S_IFLNK|S_IRWXUGO;
1077 link->data = link_root;
1078 link_name += len;
1079 }
1080 init_header(links, dir->header.root, dir->header.set, node, link_table);
1081 links->nreg = nr_entries;
1082
1083 return links;
1084}
1085
1086static bool get_links(struct ctl_dir *dir,
1087 struct ctl_table *table, struct ctl_table_root *link_root)
1088{
1089 struct ctl_table_header *head;
1090 struct ctl_table *entry, *link;
1091
1092 /* Are there links available for every entry in table? */
1093 for (entry = table; entry->procname; entry++) {
1094 const char *procname = entry->procname;
1095 link = find_entry(&head, dir, procname, strlen(procname));
1096 if (!link)
1097 return false;
1098 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1099 continue;
1100 if (S_ISLNK(link->mode) && (link->data == link_root))
1101 continue;
1102 return false;
1103 }
1104
1105 /* The checks passed. Increase the registration count on the links */
1106 for (entry = table; entry->procname; entry++) {
1107 const char *procname = entry->procname;
1108 link = find_entry(&head, dir, procname, strlen(procname));
1109 head->nreg++;
1110 }
1111 return true;
1112}
1113
1114static int insert_links(struct ctl_table_header *head)
1115{
1116 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1117 struct ctl_dir *core_parent = NULL;
1118 struct ctl_table_header *links;
1119 int err;
1120
1121 if (head->set == root_set)
1122 return 0;
1123
1124 core_parent = xlate_dir(root_set, head->parent);
1125 if (IS_ERR(core_parent))
1126 return 0;
1127
1128 if (get_links(core_parent, head->ctl_table, head->root))
1129 return 0;
1130
1131 core_parent->header.nreg++;
1132 spin_unlock(&sysctl_lock);
1133
1134 links = new_links(core_parent, head->ctl_table, head->root);
1135
1136 spin_lock(&sysctl_lock);
1137 err = -ENOMEM;
1138 if (!links)
1139 goto out;
1140
1141 err = 0;
1142 if (get_links(core_parent, head->ctl_table, head->root)) {
1143 kfree(links);
1144 goto out;
1145 }
1146
1147 err = insert_header(core_parent, links);
1148 if (err)
1149 kfree(links);
1150out:
1151 drop_sysctl_table(&core_parent->header);
1152 return err;
1153}
1154
1155/**
1156 * __register_sysctl_table - register a leaf sysctl table
1157 * @set: Sysctl tree to register on
1158 * @path: The path to the directory the sysctl table is in.
1159 * @table: the top-level table structure
1160 *
1161 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1162 * array. A completely 0 filled entry terminates the table.
1163 *
1164 * The members of the &struct ctl_table structure are used as follows:
1165 *
1166 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1167 * enter a sysctl file
1168 *
1169 * data - a pointer to data for use by proc_handler
1170 *
1171 * maxlen - the maximum size in bytes of the data
1172 *
1173 * mode - the file permissions for the /proc/sys file
1174 *
1175 * child - must be %NULL.
1176 *
1177 * proc_handler - the text handler routine (described below)
1178 *
1179 * extra1, extra2 - extra pointers usable by the proc handler routines
1180 *
1181 * Leaf nodes in the sysctl tree will be represented by a single file
1182 * under /proc; non-leaf nodes will be represented by directories.
1183 *
1184 * There must be a proc_handler routine for any terminal nodes.
1185 * Several default handlers are available to cover common cases -
1186 *
1187 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1188 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1189 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1190 *
1191 * It is the handler's job to read the input buffer from user memory
1192 * and process it. The handler should return 0 on success.
1193 *
1194 * This routine returns %NULL on a failure to register, and a pointer
1195 * to the table header on success.
1196 */
1197struct ctl_table_header *__register_sysctl_table(
1198 struct ctl_table_set *set,
1199 const char *path, struct ctl_table *table)
1200{
1201 struct ctl_table_root *root = set->dir.header.root;
1202 struct ctl_table_header *header;
1203 const char *name, *nextname;
1204 struct ctl_dir *dir;
1205 struct ctl_table *entry;
1206 struct ctl_node *node;
1207 int nr_entries = 0;
1208
1209 for (entry = table; entry->procname; entry++)
1210 nr_entries++;
1211
1212 header = kzalloc(sizeof(struct ctl_table_header) +
1213 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1214 if (!header)
1215 return NULL;
1216
1217 node = (struct ctl_node *)(header + 1);
1218 init_header(header, root, set, node, table);
1219 if (sysctl_check_table(path, table))
1220 goto fail;
1221
1222 spin_lock(&sysctl_lock);
1223 dir = &set->dir;
1224 /* Reference moved down the diretory tree get_subdir */
1225 dir->header.nreg++;
1226 spin_unlock(&sysctl_lock);
1227
1228 /* Find the directory for the ctl_table */
1229 for (name = path; name; name = nextname) {
1230 int namelen;
1231 nextname = strchr(name, '/');
1232 if (nextname) {
1233 namelen = nextname - name;
1234 nextname++;
1235 } else {
1236 namelen = strlen(name);
1237 }
1238 if (namelen == 0)
1239 continue;
1240
1241 dir = get_subdir(dir, name, namelen);
1242 if (IS_ERR(dir))
1243 goto fail;
1244 }
1245
1246 spin_lock(&sysctl_lock);
1247 if (insert_header(dir, header))
1248 goto fail_put_dir_locked;
1249
1250 drop_sysctl_table(&dir->header);
1251 spin_unlock(&sysctl_lock);
1252
1253 return header;
1254
1255fail_put_dir_locked:
1256 drop_sysctl_table(&dir->header);
1257 spin_unlock(&sysctl_lock);
1258fail:
1259 kfree(header);
1260 dump_stack();
1261 return NULL;
1262}
1263
1264/**
1265 * register_sysctl - register a sysctl table
1266 * @path: The path to the directory the sysctl table is in.
1267 * @table: the table structure
1268 *
1269 * Register a sysctl table. @table should be a filled in ctl_table
1270 * array. A completely 0 filled entry terminates the table.
1271 *
1272 * See __register_sysctl_table for more details.
1273 */
1274struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1275{
1276 return __register_sysctl_table(&sysctl_table_root.default_set,
1277 path, table);
1278}
1279EXPORT_SYMBOL(register_sysctl);
1280
1281static char *append_path(const char *path, char *pos, const char *name)
1282{
1283 int namelen;
1284 namelen = strlen(name);
1285 if (((pos - path) + namelen + 2) >= PATH_MAX)
1286 return NULL;
1287 memcpy(pos, name, namelen);
1288 pos[namelen] = '/';
1289 pos[namelen + 1] = '\0';
1290 pos += namelen + 1;
1291 return pos;
1292}
1293
1294static int count_subheaders(struct ctl_table *table)
1295{
1296 int has_files = 0;
1297 int nr_subheaders = 0;
1298 struct ctl_table *entry;
1299
1300 /* special case: no directory and empty directory */
1301 if (!table || !table->procname)
1302 return 1;
1303
1304 for (entry = table; entry->procname; entry++) {
1305 if (entry->child)
1306 nr_subheaders += count_subheaders(entry->child);
1307 else
1308 has_files = 1;
1309 }
1310 return nr_subheaders + has_files;
1311}
1312
1313static int register_leaf_sysctl_tables(const char *path, char *pos,
1314 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1315 struct ctl_table *table)
1316{
1317 struct ctl_table *ctl_table_arg = NULL;
1318 struct ctl_table *entry, *files;
1319 int nr_files = 0;
1320 int nr_dirs = 0;
1321 int err = -ENOMEM;
1322
1323 for (entry = table; entry->procname; entry++) {
1324 if (entry->child)
1325 nr_dirs++;
1326 else
1327 nr_files++;
1328 }
1329
1330 files = table;
1331 /* If there are mixed files and directories we need a new table */
1332 if (nr_dirs && nr_files) {
1333 struct ctl_table *new;
1334 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1335 GFP_KERNEL);
1336 if (!files)
1337 goto out;
1338
1339 ctl_table_arg = files;
1340 for (new = files, entry = table; entry->procname; entry++) {
1341 if (entry->child)
1342 continue;
1343 *new = *entry;
1344 new++;
1345 }
1346 }
1347
1348 /* Register everything except a directory full of subdirectories */
1349 if (nr_files || !nr_dirs) {
1350 struct ctl_table_header *header;
1351 header = __register_sysctl_table(set, path, files);
1352 if (!header) {
1353 kfree(ctl_table_arg);
1354 goto out;
1355 }
1356
1357 /* Remember if we need to free the file table */
1358 header->ctl_table_arg = ctl_table_arg;
1359 **subheader = header;
1360 (*subheader)++;
1361 }
1362
1363 /* Recurse into the subdirectories. */
1364 for (entry = table; entry->procname; entry++) {
1365 char *child_pos;
1366
1367 if (!entry->child)
1368 continue;
1369
1370 err = -ENAMETOOLONG;
1371 child_pos = append_path(path, pos, entry->procname);
1372 if (!child_pos)
1373 goto out;
1374
1375 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1376 set, entry->child);
1377 pos[0] = '\0';
1378 if (err)
1379 goto out;
1380 }
1381 err = 0;
1382out:
1383 /* On failure our caller will unregister all registered subheaders */
1384 return err;
1385}
1386
1387/**
1388 * __register_sysctl_paths - register a sysctl table hierarchy
1389 * @set: Sysctl tree to register on
1390 * @path: The path to the directory the sysctl table is in.
1391 * @table: the top-level table structure
1392 *
1393 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1394 * array. A completely 0 filled entry terminates the table.
1395 *
1396 * See __register_sysctl_table for more details.
1397 */
1398struct ctl_table_header *__register_sysctl_paths(
1399 struct ctl_table_set *set,
1400 const struct ctl_path *path, struct ctl_table *table)
1401{
1402 struct ctl_table *ctl_table_arg = table;
1403 int nr_subheaders = count_subheaders(table);
1404 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1405 const struct ctl_path *component;
1406 char *new_path, *pos;
1407
1408 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1409 if (!new_path)
1410 return NULL;
1411
1412 pos[0] = '\0';
1413 for (component = path; component->procname; component++) {
1414 pos = append_path(new_path, pos, component->procname);
1415 if (!pos)
1416 goto out;
1417 }
1418 while (table->procname && table->child && !table[1].procname) {
1419 pos = append_path(new_path, pos, table->procname);
1420 if (!pos)
1421 goto out;
1422 table = table->child;
1423 }
1424 if (nr_subheaders == 1) {
1425 header = __register_sysctl_table(set, new_path, table);
1426 if (header)
1427 header->ctl_table_arg = ctl_table_arg;
1428 } else {
1429 header = kzalloc(sizeof(*header) +
1430 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1431 if (!header)
1432 goto out;
1433
1434 subheaders = (struct ctl_table_header **) (header + 1);
1435 subheader = subheaders;
1436 header->ctl_table_arg = ctl_table_arg;
1437
1438 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1439 set, table))
1440 goto err_register_leaves;
1441 }
1442
1443out:
1444 kfree(new_path);
1445 return header;
1446
1447err_register_leaves:
1448 while (subheader > subheaders) {
1449 struct ctl_table_header *subh = *(--subheader);
1450 struct ctl_table *table = subh->ctl_table_arg;
1451 unregister_sysctl_table(subh);
1452 kfree(table);
1453 }
1454 kfree(header);
1455 header = NULL;
1456 goto out;
1457}
1458
1459/**
1460 * register_sysctl_table_path - register a sysctl table hierarchy
1461 * @path: The path to the directory the sysctl table is in.
1462 * @table: the top-level table structure
1463 *
1464 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1465 * array. A completely 0 filled entry terminates the table.
1466 *
1467 * See __register_sysctl_paths for more details.
1468 */
1469struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1470 struct ctl_table *table)
1471{
1472 return __register_sysctl_paths(&sysctl_table_root.default_set,
1473 path, table);
1474}
1475EXPORT_SYMBOL(register_sysctl_paths);
1476
1477/**
1478 * register_sysctl_table - register a sysctl table hierarchy
1479 * @table: the top-level table structure
1480 *
1481 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1482 * array. A completely 0 filled entry terminates the table.
1483 *
1484 * See register_sysctl_paths for more details.
1485 */
1486struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1487{
1488 static const struct ctl_path null_path[] = { {} };
1489
1490 return register_sysctl_paths(null_path, table);
1491}
1492EXPORT_SYMBOL(register_sysctl_table);
1493
1494static void put_links(struct ctl_table_header *header)
1495{
1496 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1497 struct ctl_table_root *root = header->root;
1498 struct ctl_dir *parent = header->parent;
1499 struct ctl_dir *core_parent;
1500 struct ctl_table *entry;
1501
1502 if (header->set == root_set)
1503 return;
1504
1505 core_parent = xlate_dir(root_set, parent);
1506 if (IS_ERR(core_parent))
1507 return;
1508
1509 for (entry = header->ctl_table; entry->procname; entry++) {
1510 struct ctl_table_header *link_head;
1511 struct ctl_table *link;
1512 const char *name = entry->procname;
1513
1514 link = find_entry(&link_head, core_parent, name, strlen(name));
1515 if (link &&
1516 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1517 (S_ISLNK(link->mode) && (link->data == root)))) {
1518 drop_sysctl_table(link_head);
1519 }
1520 else {
1521 printk(KERN_ERR "sysctl link missing during unregister: ");
1522 sysctl_print_dir(parent);
1523 printk(KERN_CONT "/%s\n", name);
1524 }
1525 }
1526}
1527
1528static void drop_sysctl_table(struct ctl_table_header *header)
1529{
1530 struct ctl_dir *parent = header->parent;
1531
1532 if (--header->nreg)
1533 return;
1534
1535 put_links(header);
1536 start_unregistering(header);
1537 if (!--header->count)
1538 kfree_rcu(header, rcu);
1539
1540 if (parent)
1541 drop_sysctl_table(&parent->header);
1542}
1543
1544/**
1545 * unregister_sysctl_table - unregister a sysctl table hierarchy
1546 * @header: the header returned from register_sysctl_table
1547 *
1548 * Unregisters the sysctl table and all children. proc entries may not
1549 * actually be removed until they are no longer used by anyone.
1550 */
1551void unregister_sysctl_table(struct ctl_table_header * header)
1552{
1553 int nr_subheaders;
1554 might_sleep();
1555
1556 if (header == NULL)
1557 return;
1558
1559 nr_subheaders = count_subheaders(header->ctl_table_arg);
1560 if (unlikely(nr_subheaders > 1)) {
1561 struct ctl_table_header **subheaders;
1562 int i;
1563
1564 subheaders = (struct ctl_table_header **)(header + 1);
1565 for (i = nr_subheaders -1; i >= 0; i--) {
1566 struct ctl_table_header *subh = subheaders[i];
1567 struct ctl_table *table = subh->ctl_table_arg;
1568 unregister_sysctl_table(subh);
1569 kfree(table);
1570 }
1571 kfree(header);
1572 return;
1573 }
1574
1575 spin_lock(&sysctl_lock);
1576 drop_sysctl_table(header);
1577 spin_unlock(&sysctl_lock);
1578}
1579EXPORT_SYMBOL(unregister_sysctl_table);
1580
1581void setup_sysctl_set(struct ctl_table_set *set,
1582 struct ctl_table_root *root,
1583 int (*is_seen)(struct ctl_table_set *))
1584{
1585 memset(set, 0, sizeof(*set));
1586 set->is_seen = is_seen;
1587 init_header(&set->dir.header, root, set, NULL, root_table);
1588}
1589
1590void retire_sysctl_set(struct ctl_table_set *set)
1591{
1592 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1593}
1594
1595int __init proc_sys_init(void)
1596{
1597 struct proc_dir_entry *proc_sys_root;
1598
1599 proc_sys_root = proc_mkdir("sys", NULL);
1600 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1601 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1602 proc_sys_root->nlink = 0;
1603
1604 return sysctl_init();
1605}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * /proc/sys support
4 */
5#include <linux/init.h>
6#include <linux/sysctl.h>
7#include <linux/poll.h>
8#include <linux/proc_fs.h>
9#include <linux/printk.h>
10#include <linux/security.h>
11#include <linux/sched.h>
12#include <linux/cred.h>
13#include <linux/namei.h>
14#include <linux/mm.h>
15#include <linux/uio.h>
16#include <linux/module.h>
17#include <linux/bpf-cgroup.h>
18#include <linux/mount.h>
19#include <linux/kmemleak.h>
20#include <linux/lockdep.h>
21#include "internal.h"
22
23#define list_for_each_table_entry(entry, header) \
24 entry = header->ctl_table; \
25 for (size_t i = 0 ; i < header->ctl_table_size; ++i, entry++)
26
27static const struct dentry_operations proc_sys_dentry_operations;
28static const struct file_operations proc_sys_file_operations;
29static const struct inode_operations proc_sys_inode_operations;
30static const struct file_operations proc_sys_dir_file_operations;
31static const struct inode_operations proc_sys_dir_operations;
32
33/*
34 * Support for permanently empty directories.
35 * Must be non-empty to avoid sharing an address with other tables.
36 */
37static const struct ctl_table sysctl_mount_point[] = {
38 { }
39};
40
41/**
42 * register_sysctl_mount_point() - registers a sysctl mount point
43 * @path: path for the mount point
44 *
45 * Used to create a permanently empty directory to serve as mount point.
46 * There are some subtle but important permission checks this allows in the
47 * case of unprivileged mounts.
48 */
49struct ctl_table_header *register_sysctl_mount_point(const char *path)
50{
51 return register_sysctl_sz(path, sysctl_mount_point, 0);
52}
53EXPORT_SYMBOL(register_sysctl_mount_point);
54
55#define sysctl_is_perm_empty_ctl_header(hptr) \
56 (hptr->type == SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
57#define sysctl_set_perm_empty_ctl_header(hptr) \
58 (hptr->type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
59#define sysctl_clear_perm_empty_ctl_header(hptr) \
60 (hptr->type = SYSCTL_TABLE_TYPE_DEFAULT)
61
62void proc_sys_poll_notify(struct ctl_table_poll *poll)
63{
64 if (!poll)
65 return;
66
67 atomic_inc(&poll->event);
68 wake_up_interruptible(&poll->wait);
69}
70
71static const struct ctl_table root_table[] = {
72 {
73 .procname = "",
74 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
75 },
76};
77static struct ctl_table_root sysctl_table_root = {
78 .default_set.dir.header = {
79 {{.count = 1,
80 .nreg = 1,
81 .ctl_table = root_table }},
82 .ctl_table_arg = root_table,
83 .root = &sysctl_table_root,
84 .set = &sysctl_table_root.default_set,
85 },
86};
87
88static DEFINE_SPINLOCK(sysctl_lock);
89
90static void drop_sysctl_table(struct ctl_table_header *header);
91static int sysctl_follow_link(struct ctl_table_header **phead,
92 const struct ctl_table **pentry);
93static int insert_links(struct ctl_table_header *head);
94static void put_links(struct ctl_table_header *header);
95
96static void sysctl_print_dir(struct ctl_dir *dir)
97{
98 if (dir->header.parent)
99 sysctl_print_dir(dir->header.parent);
100 pr_cont("%s/", dir->header.ctl_table[0].procname);
101}
102
103static int namecmp(const char *name1, int len1, const char *name2, int len2)
104{
105 int cmp;
106
107 cmp = memcmp(name1, name2, min(len1, len2));
108 if (cmp == 0)
109 cmp = len1 - len2;
110 return cmp;
111}
112
113static const struct ctl_table *find_entry(struct ctl_table_header **phead,
114 struct ctl_dir *dir, const char *name, int namelen)
115{
116 struct ctl_table_header *head;
117 const struct ctl_table *entry;
118 struct rb_node *node = dir->root.rb_node;
119
120 lockdep_assert_held(&sysctl_lock);
121
122 while (node)
123 {
124 struct ctl_node *ctl_node;
125 const char *procname;
126 int cmp;
127
128 ctl_node = rb_entry(node, struct ctl_node, node);
129 head = ctl_node->header;
130 entry = &head->ctl_table[ctl_node - head->node];
131 procname = entry->procname;
132
133 cmp = namecmp(name, namelen, procname, strlen(procname));
134 if (cmp < 0)
135 node = node->rb_left;
136 else if (cmp > 0)
137 node = node->rb_right;
138 else {
139 *phead = head;
140 return entry;
141 }
142 }
143 return NULL;
144}
145
146static int insert_entry(struct ctl_table_header *head, const struct ctl_table *entry)
147{
148 struct rb_node *node = &head->node[entry - head->ctl_table].node;
149 struct rb_node **p = &head->parent->root.rb_node;
150 struct rb_node *parent = NULL;
151 const char *name = entry->procname;
152 int namelen = strlen(name);
153
154 while (*p) {
155 struct ctl_table_header *parent_head;
156 const struct ctl_table *parent_entry;
157 struct ctl_node *parent_node;
158 const char *parent_name;
159 int cmp;
160
161 parent = *p;
162 parent_node = rb_entry(parent, struct ctl_node, node);
163 parent_head = parent_node->header;
164 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
165 parent_name = parent_entry->procname;
166
167 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
168 if (cmp < 0)
169 p = &(*p)->rb_left;
170 else if (cmp > 0)
171 p = &(*p)->rb_right;
172 else {
173 pr_err("sysctl duplicate entry: ");
174 sysctl_print_dir(head->parent);
175 pr_cont("%s\n", entry->procname);
176 return -EEXIST;
177 }
178 }
179
180 rb_link_node(node, parent, p);
181 rb_insert_color(node, &head->parent->root);
182 return 0;
183}
184
185static void erase_entry(struct ctl_table_header *head, const struct ctl_table *entry)
186{
187 struct rb_node *node = &head->node[entry - head->ctl_table].node;
188
189 rb_erase(node, &head->parent->root);
190}
191
192static void init_header(struct ctl_table_header *head,
193 struct ctl_table_root *root, struct ctl_table_set *set,
194 struct ctl_node *node, const struct ctl_table *table, size_t table_size)
195{
196 head->ctl_table = table;
197 head->ctl_table_size = table_size;
198 head->ctl_table_arg = table;
199 head->used = 0;
200 head->count = 1;
201 head->nreg = 1;
202 head->unregistering = NULL;
203 head->root = root;
204 head->set = set;
205 head->parent = NULL;
206 head->node = node;
207 INIT_HLIST_HEAD(&head->inodes);
208 if (node) {
209 const struct ctl_table *entry;
210
211 list_for_each_table_entry(entry, head) {
212 node->header = head;
213 node++;
214 }
215 }
216 if (table == sysctl_mount_point)
217 sysctl_set_perm_empty_ctl_header(head);
218}
219
220static void erase_header(struct ctl_table_header *head)
221{
222 const struct ctl_table *entry;
223
224 list_for_each_table_entry(entry, head)
225 erase_entry(head, entry);
226}
227
228static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
229{
230 const struct ctl_table *entry;
231 struct ctl_table_header *dir_h = &dir->header;
232 int err;
233
234
235 /* Is this a permanently empty directory? */
236 if (sysctl_is_perm_empty_ctl_header(dir_h))
237 return -EROFS;
238
239 /* Am I creating a permanently empty directory? */
240 if (sysctl_is_perm_empty_ctl_header(header)) {
241 if (!RB_EMPTY_ROOT(&dir->root))
242 return -EINVAL;
243 sysctl_set_perm_empty_ctl_header(dir_h);
244 }
245
246 dir_h->nreg++;
247 header->parent = dir;
248 err = insert_links(header);
249 if (err)
250 goto fail_links;
251 list_for_each_table_entry(entry, header) {
252 err = insert_entry(header, entry);
253 if (err)
254 goto fail;
255 }
256 return 0;
257fail:
258 erase_header(header);
259 put_links(header);
260fail_links:
261 if (header->ctl_table == sysctl_mount_point)
262 sysctl_clear_perm_empty_ctl_header(dir_h);
263 header->parent = NULL;
264 drop_sysctl_table(dir_h);
265 return err;
266}
267
268static int use_table(struct ctl_table_header *p)
269{
270 lockdep_assert_held(&sysctl_lock);
271
272 if (unlikely(p->unregistering))
273 return 0;
274 p->used++;
275 return 1;
276}
277
278static void unuse_table(struct ctl_table_header *p)
279{
280 lockdep_assert_held(&sysctl_lock);
281
282 if (!--p->used)
283 if (unlikely(p->unregistering))
284 complete(p->unregistering);
285}
286
287static void proc_sys_invalidate_dcache(struct ctl_table_header *head)
288{
289 proc_invalidate_siblings_dcache(&head->inodes, &sysctl_lock);
290}
291
292static void start_unregistering(struct ctl_table_header *p)
293{
294 /* will reacquire if has to wait */
295 lockdep_assert_held(&sysctl_lock);
296
297 /*
298 * if p->used is 0, nobody will ever touch that entry again;
299 * we'll eliminate all paths to it before dropping sysctl_lock
300 */
301 if (unlikely(p->used)) {
302 struct completion wait;
303 init_completion(&wait);
304 p->unregistering = &wait;
305 spin_unlock(&sysctl_lock);
306 wait_for_completion(&wait);
307 } else {
308 /* anything non-NULL; we'll never dereference it */
309 p->unregistering = ERR_PTR(-EINVAL);
310 spin_unlock(&sysctl_lock);
311 }
312 /*
313 * Invalidate dentries for unregistered sysctls: namespaced sysctls
314 * can have duplicate names and contaminate dcache very badly.
315 */
316 proc_sys_invalidate_dcache(p);
317 /*
318 * do not remove from the list until nobody holds it; walking the
319 * list in do_sysctl() relies on that.
320 */
321 spin_lock(&sysctl_lock);
322 erase_header(p);
323}
324
325static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
326{
327 BUG_ON(!head);
328 spin_lock(&sysctl_lock);
329 if (!use_table(head))
330 head = ERR_PTR(-ENOENT);
331 spin_unlock(&sysctl_lock);
332 return head;
333}
334
335static void sysctl_head_finish(struct ctl_table_header *head)
336{
337 if (!head)
338 return;
339 spin_lock(&sysctl_lock);
340 unuse_table(head);
341 spin_unlock(&sysctl_lock);
342}
343
344static struct ctl_table_set *
345lookup_header_set(struct ctl_table_root *root)
346{
347 struct ctl_table_set *set = &root->default_set;
348 if (root->lookup)
349 set = root->lookup(root);
350 return set;
351}
352
353static const struct ctl_table *lookup_entry(struct ctl_table_header **phead,
354 struct ctl_dir *dir,
355 const char *name, int namelen)
356{
357 struct ctl_table_header *head;
358 const struct ctl_table *entry;
359
360 spin_lock(&sysctl_lock);
361 entry = find_entry(&head, dir, name, namelen);
362 if (entry && use_table(head))
363 *phead = head;
364 else
365 entry = NULL;
366 spin_unlock(&sysctl_lock);
367 return entry;
368}
369
370static struct ctl_node *first_usable_entry(struct rb_node *node)
371{
372 struct ctl_node *ctl_node;
373
374 for (;node; node = rb_next(node)) {
375 ctl_node = rb_entry(node, struct ctl_node, node);
376 if (use_table(ctl_node->header))
377 return ctl_node;
378 }
379 return NULL;
380}
381
382static void first_entry(struct ctl_dir *dir,
383 struct ctl_table_header **phead, const struct ctl_table **pentry)
384{
385 struct ctl_table_header *head = NULL;
386 const struct ctl_table *entry = NULL;
387 struct ctl_node *ctl_node;
388
389 spin_lock(&sysctl_lock);
390 ctl_node = first_usable_entry(rb_first(&dir->root));
391 spin_unlock(&sysctl_lock);
392 if (ctl_node) {
393 head = ctl_node->header;
394 entry = &head->ctl_table[ctl_node - head->node];
395 }
396 *phead = head;
397 *pentry = entry;
398}
399
400static void next_entry(struct ctl_table_header **phead, const struct ctl_table **pentry)
401{
402 struct ctl_table_header *head = *phead;
403 const struct ctl_table *entry = *pentry;
404 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
405
406 spin_lock(&sysctl_lock);
407 unuse_table(head);
408
409 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
410 spin_unlock(&sysctl_lock);
411 head = NULL;
412 if (ctl_node) {
413 head = ctl_node->header;
414 entry = &head->ctl_table[ctl_node - head->node];
415 }
416 *phead = head;
417 *pentry = entry;
418}
419
420/*
421 * sysctl_perm does NOT grant the superuser all rights automatically, because
422 * some sysctl variables are readonly even to root.
423 */
424
425static int test_perm(int mode, int op)
426{
427 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
428 mode >>= 6;
429 else if (in_egroup_p(GLOBAL_ROOT_GID))
430 mode >>= 3;
431 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
432 return 0;
433 return -EACCES;
434}
435
436static int sysctl_perm(struct ctl_table_header *head, const struct ctl_table *table, int op)
437{
438 struct ctl_table_root *root = head->root;
439 int mode;
440
441 if (root->permissions)
442 mode = root->permissions(head, table);
443 else
444 mode = table->mode;
445
446 return test_perm(mode, op);
447}
448
449static struct inode *proc_sys_make_inode(struct super_block *sb,
450 struct ctl_table_header *head, const struct ctl_table *table)
451{
452 struct ctl_table_root *root = head->root;
453 struct inode *inode;
454 struct proc_inode *ei;
455
456 inode = new_inode(sb);
457 if (!inode)
458 return ERR_PTR(-ENOMEM);
459
460 inode->i_ino = get_next_ino();
461
462 ei = PROC_I(inode);
463
464 spin_lock(&sysctl_lock);
465 if (unlikely(head->unregistering)) {
466 spin_unlock(&sysctl_lock);
467 iput(inode);
468 return ERR_PTR(-ENOENT);
469 }
470 ei->sysctl = head;
471 ei->sysctl_entry = table;
472 hlist_add_head_rcu(&ei->sibling_inodes, &head->inodes);
473 head->count++;
474 spin_unlock(&sysctl_lock);
475
476 simple_inode_init_ts(inode);
477 inode->i_mode = table->mode;
478 if (!S_ISDIR(table->mode)) {
479 inode->i_mode |= S_IFREG;
480 inode->i_op = &proc_sys_inode_operations;
481 inode->i_fop = &proc_sys_file_operations;
482 } else {
483 inode->i_mode |= S_IFDIR;
484 inode->i_op = &proc_sys_dir_operations;
485 inode->i_fop = &proc_sys_dir_file_operations;
486 if (sysctl_is_perm_empty_ctl_header(head))
487 make_empty_dir_inode(inode);
488 }
489
490 inode->i_uid = GLOBAL_ROOT_UID;
491 inode->i_gid = GLOBAL_ROOT_GID;
492 if (root->set_ownership)
493 root->set_ownership(head, &inode->i_uid, &inode->i_gid);
494
495 return inode;
496}
497
498void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
499{
500 spin_lock(&sysctl_lock);
501 hlist_del_init_rcu(&PROC_I(inode)->sibling_inodes);
502 if (!--head->count)
503 kfree_rcu(head, rcu);
504 spin_unlock(&sysctl_lock);
505}
506
507static struct ctl_table_header *grab_header(struct inode *inode)
508{
509 struct ctl_table_header *head = PROC_I(inode)->sysctl;
510 if (!head)
511 head = &sysctl_table_root.default_set.dir.header;
512 return sysctl_head_grab(head);
513}
514
515static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
516 unsigned int flags)
517{
518 struct ctl_table_header *head = grab_header(dir);
519 struct ctl_table_header *h = NULL;
520 const struct qstr *name = &dentry->d_name;
521 const struct ctl_table *p;
522 struct inode *inode;
523 struct dentry *err = ERR_PTR(-ENOENT);
524 struct ctl_dir *ctl_dir;
525 int ret;
526
527 if (IS_ERR(head))
528 return ERR_CAST(head);
529
530 ctl_dir = container_of(head, struct ctl_dir, header);
531
532 p = lookup_entry(&h, ctl_dir, name->name, name->len);
533 if (!p)
534 goto out;
535
536 if (S_ISLNK(p->mode)) {
537 ret = sysctl_follow_link(&h, &p);
538 err = ERR_PTR(ret);
539 if (ret)
540 goto out;
541 }
542
543 d_set_d_op(dentry, &proc_sys_dentry_operations);
544 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
545 err = d_splice_alias(inode, dentry);
546
547out:
548 if (h)
549 sysctl_head_finish(h);
550 sysctl_head_finish(head);
551 return err;
552}
553
554static ssize_t proc_sys_call_handler(struct kiocb *iocb, struct iov_iter *iter,
555 int write)
556{
557 struct inode *inode = file_inode(iocb->ki_filp);
558 struct ctl_table_header *head = grab_header(inode);
559 const struct ctl_table *table = PROC_I(inode)->sysctl_entry;
560 size_t count = iov_iter_count(iter);
561 char *kbuf;
562 ssize_t error;
563
564 if (IS_ERR(head))
565 return PTR_ERR(head);
566
567 /*
568 * At this point we know that the sysctl was not unregistered
569 * and won't be until we finish.
570 */
571 error = -EPERM;
572 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
573 goto out;
574
575 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
576 error = -EINVAL;
577 if (!table->proc_handler)
578 goto out;
579
580 /* don't even try if the size is too large */
581 error = -ENOMEM;
582 if (count >= KMALLOC_MAX_SIZE)
583 goto out;
584 kbuf = kvzalloc(count + 1, GFP_KERNEL);
585 if (!kbuf)
586 goto out;
587
588 if (write) {
589 error = -EFAULT;
590 if (!copy_from_iter_full(kbuf, count, iter))
591 goto out_free_buf;
592 kbuf[count] = '\0';
593 }
594
595 error = BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, &kbuf, &count,
596 &iocb->ki_pos);
597 if (error)
598 goto out_free_buf;
599
600 /* careful: calling conventions are nasty here */
601 error = table->proc_handler(table, write, kbuf, &count, &iocb->ki_pos);
602 if (error)
603 goto out_free_buf;
604
605 if (!write) {
606 error = -EFAULT;
607 if (copy_to_iter(kbuf, count, iter) < count)
608 goto out_free_buf;
609 }
610
611 error = count;
612out_free_buf:
613 kvfree(kbuf);
614out:
615 sysctl_head_finish(head);
616
617 return error;
618}
619
620static ssize_t proc_sys_read(struct kiocb *iocb, struct iov_iter *iter)
621{
622 return proc_sys_call_handler(iocb, iter, 0);
623}
624
625static ssize_t proc_sys_write(struct kiocb *iocb, struct iov_iter *iter)
626{
627 return proc_sys_call_handler(iocb, iter, 1);
628}
629
630static int proc_sys_open(struct inode *inode, struct file *filp)
631{
632 struct ctl_table_header *head = grab_header(inode);
633 const struct ctl_table *table = PROC_I(inode)->sysctl_entry;
634
635 /* sysctl was unregistered */
636 if (IS_ERR(head))
637 return PTR_ERR(head);
638
639 if (table->poll)
640 filp->private_data = proc_sys_poll_event(table->poll);
641
642 sysctl_head_finish(head);
643
644 return 0;
645}
646
647static __poll_t proc_sys_poll(struct file *filp, poll_table *wait)
648{
649 struct inode *inode = file_inode(filp);
650 struct ctl_table_header *head = grab_header(inode);
651 const struct ctl_table *table = PROC_I(inode)->sysctl_entry;
652 __poll_t ret = DEFAULT_POLLMASK;
653 unsigned long event;
654
655 /* sysctl was unregistered */
656 if (IS_ERR(head))
657 return EPOLLERR | EPOLLHUP;
658
659 if (!table->proc_handler)
660 goto out;
661
662 if (!table->poll)
663 goto out;
664
665 event = (unsigned long)filp->private_data;
666 poll_wait(filp, &table->poll->wait, wait);
667
668 if (event != atomic_read(&table->poll->event)) {
669 filp->private_data = proc_sys_poll_event(table->poll);
670 ret = EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI;
671 }
672
673out:
674 sysctl_head_finish(head);
675
676 return ret;
677}
678
679static bool proc_sys_fill_cache(struct file *file,
680 struct dir_context *ctx,
681 struct ctl_table_header *head,
682 const struct ctl_table *table)
683{
684 struct dentry *child, *dir = file->f_path.dentry;
685 struct inode *inode;
686 struct qstr qname;
687 ino_t ino = 0;
688 unsigned type = DT_UNKNOWN;
689
690 qname.name = table->procname;
691 qname.len = strlen(table->procname);
692 qname.hash = full_name_hash(dir, qname.name, qname.len);
693
694 child = d_lookup(dir, &qname);
695 if (!child) {
696 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
697 child = d_alloc_parallel(dir, &qname, &wq);
698 if (IS_ERR(child))
699 return false;
700 if (d_in_lookup(child)) {
701 struct dentry *res;
702 d_set_d_op(child, &proc_sys_dentry_operations);
703 inode = proc_sys_make_inode(dir->d_sb, head, table);
704 res = d_splice_alias(inode, child);
705 d_lookup_done(child);
706 if (unlikely(res)) {
707 dput(child);
708
709 if (IS_ERR(res))
710 return false;
711
712 child = res;
713 }
714 }
715 }
716 inode = d_inode(child);
717 ino = inode->i_ino;
718 type = inode->i_mode >> 12;
719 dput(child);
720 return dir_emit(ctx, qname.name, qname.len, ino, type);
721}
722
723static bool proc_sys_link_fill_cache(struct file *file,
724 struct dir_context *ctx,
725 struct ctl_table_header *head,
726 const struct ctl_table *table)
727{
728 bool ret = true;
729
730 head = sysctl_head_grab(head);
731 if (IS_ERR(head))
732 return false;
733
734 /* It is not an error if we can not follow the link ignore it */
735 if (sysctl_follow_link(&head, &table))
736 goto out;
737
738 ret = proc_sys_fill_cache(file, ctx, head, table);
739out:
740 sysctl_head_finish(head);
741 return ret;
742}
743
744static int scan(struct ctl_table_header *head, const struct ctl_table *table,
745 unsigned long *pos, struct file *file,
746 struct dir_context *ctx)
747{
748 bool res;
749
750 if ((*pos)++ < ctx->pos)
751 return true;
752
753 if (unlikely(S_ISLNK(table->mode)))
754 res = proc_sys_link_fill_cache(file, ctx, head, table);
755 else
756 res = proc_sys_fill_cache(file, ctx, head, table);
757
758 if (res)
759 ctx->pos = *pos;
760
761 return res;
762}
763
764static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
765{
766 struct ctl_table_header *head = grab_header(file_inode(file));
767 struct ctl_table_header *h = NULL;
768 const struct ctl_table *entry;
769 struct ctl_dir *ctl_dir;
770 unsigned long pos;
771
772 if (IS_ERR(head))
773 return PTR_ERR(head);
774
775 ctl_dir = container_of(head, struct ctl_dir, header);
776
777 if (!dir_emit_dots(file, ctx))
778 goto out;
779
780 pos = 2;
781
782 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
783 if (!scan(h, entry, &pos, file, ctx)) {
784 sysctl_head_finish(h);
785 break;
786 }
787 }
788out:
789 sysctl_head_finish(head);
790 return 0;
791}
792
793static int proc_sys_permission(struct mnt_idmap *idmap,
794 struct inode *inode, int mask)
795{
796 /*
797 * sysctl entries that are not writeable,
798 * are _NOT_ writeable, capabilities or not.
799 */
800 struct ctl_table_header *head;
801 const struct ctl_table *table;
802 int error;
803
804 /* Executable files are not allowed under /proc/sys/ */
805 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
806 return -EACCES;
807
808 head = grab_header(inode);
809 if (IS_ERR(head))
810 return PTR_ERR(head);
811
812 table = PROC_I(inode)->sysctl_entry;
813 if (!table) /* global root - r-xr-xr-x */
814 error = mask & MAY_WRITE ? -EACCES : 0;
815 else /* Use the permissions on the sysctl table entry */
816 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
817
818 sysctl_head_finish(head);
819 return error;
820}
821
822static int proc_sys_setattr(struct mnt_idmap *idmap,
823 struct dentry *dentry, struct iattr *attr)
824{
825 struct inode *inode = d_inode(dentry);
826 int error;
827
828 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
829 return -EPERM;
830
831 error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
832 if (error)
833 return error;
834
835 setattr_copy(&nop_mnt_idmap, inode, attr);
836 return 0;
837}
838
839static int proc_sys_getattr(struct mnt_idmap *idmap,
840 const struct path *path, struct kstat *stat,
841 u32 request_mask, unsigned int query_flags)
842{
843 struct inode *inode = d_inode(path->dentry);
844 struct ctl_table_header *head = grab_header(inode);
845 const struct ctl_table *table = PROC_I(inode)->sysctl_entry;
846
847 if (IS_ERR(head))
848 return PTR_ERR(head);
849
850 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
851 if (table)
852 stat->mode = (stat->mode & S_IFMT) | table->mode;
853
854 sysctl_head_finish(head);
855 return 0;
856}
857
858static const struct file_operations proc_sys_file_operations = {
859 .open = proc_sys_open,
860 .poll = proc_sys_poll,
861 .read_iter = proc_sys_read,
862 .write_iter = proc_sys_write,
863 .splice_read = copy_splice_read,
864 .splice_write = iter_file_splice_write,
865 .llseek = default_llseek,
866};
867
868static const struct file_operations proc_sys_dir_file_operations = {
869 .read = generic_read_dir,
870 .iterate_shared = proc_sys_readdir,
871 .llseek = generic_file_llseek,
872};
873
874static const struct inode_operations proc_sys_inode_operations = {
875 .permission = proc_sys_permission,
876 .setattr = proc_sys_setattr,
877 .getattr = proc_sys_getattr,
878};
879
880static const struct inode_operations proc_sys_dir_operations = {
881 .lookup = proc_sys_lookup,
882 .permission = proc_sys_permission,
883 .setattr = proc_sys_setattr,
884 .getattr = proc_sys_getattr,
885};
886
887static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
888{
889 if (flags & LOOKUP_RCU)
890 return -ECHILD;
891 return !PROC_I(d_inode(dentry))->sysctl->unregistering;
892}
893
894static int proc_sys_delete(const struct dentry *dentry)
895{
896 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
897}
898
899static int sysctl_is_seen(struct ctl_table_header *p)
900{
901 struct ctl_table_set *set = p->set;
902 int res;
903 spin_lock(&sysctl_lock);
904 if (p->unregistering)
905 res = 0;
906 else if (!set->is_seen)
907 res = 1;
908 else
909 res = set->is_seen(set);
910 spin_unlock(&sysctl_lock);
911 return res;
912}
913
914static int proc_sys_compare(const struct dentry *dentry,
915 unsigned int len, const char *str, const struct qstr *name)
916{
917 struct ctl_table_header *head;
918 struct inode *inode;
919
920 /* Although proc doesn't have negative dentries, rcu-walk means
921 * that inode here can be NULL */
922 /* AV: can it, indeed? */
923 inode = d_inode_rcu(dentry);
924 if (!inode)
925 return 1;
926 if (name->len != len)
927 return 1;
928 if (memcmp(name->name, str, len))
929 return 1;
930 head = rcu_dereference(PROC_I(inode)->sysctl);
931 return !head || !sysctl_is_seen(head);
932}
933
934static const struct dentry_operations proc_sys_dentry_operations = {
935 .d_revalidate = proc_sys_revalidate,
936 .d_delete = proc_sys_delete,
937 .d_compare = proc_sys_compare,
938};
939
940static struct ctl_dir *find_subdir(struct ctl_dir *dir,
941 const char *name, int namelen)
942{
943 struct ctl_table_header *head;
944 const struct ctl_table *entry;
945
946 entry = find_entry(&head, dir, name, namelen);
947 if (!entry)
948 return ERR_PTR(-ENOENT);
949 if (!S_ISDIR(entry->mode))
950 return ERR_PTR(-ENOTDIR);
951 return container_of(head, struct ctl_dir, header);
952}
953
954static struct ctl_dir *new_dir(struct ctl_table_set *set,
955 const char *name, int namelen)
956{
957 struct ctl_table *table;
958 struct ctl_dir *new;
959 struct ctl_node *node;
960 char *new_name;
961
962 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
963 sizeof(struct ctl_table) + namelen + 1,
964 GFP_KERNEL);
965 if (!new)
966 return NULL;
967
968 node = (struct ctl_node *)(new + 1);
969 table = (struct ctl_table *)(node + 1);
970 new_name = (char *)(table + 1);
971 memcpy(new_name, name, namelen);
972 table[0].procname = new_name;
973 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
974 init_header(&new->header, set->dir.header.root, set, node, table, 1);
975
976 return new;
977}
978
979/**
980 * get_subdir - find or create a subdir with the specified name.
981 * @dir: Directory to create the subdirectory in
982 * @name: The name of the subdirectory to find or create
983 * @namelen: The length of name
984 *
985 * Takes a directory with an elevated reference count so we know that
986 * if we drop the lock the directory will not go away. Upon success
987 * the reference is moved from @dir to the returned subdirectory.
988 * Upon error an error code is returned and the reference on @dir is
989 * simply dropped.
990 */
991static struct ctl_dir *get_subdir(struct ctl_dir *dir,
992 const char *name, int namelen)
993{
994 struct ctl_table_set *set = dir->header.set;
995 struct ctl_dir *subdir, *new = NULL;
996 int err;
997
998 spin_lock(&sysctl_lock);
999 subdir = find_subdir(dir, name, namelen);
1000 if (!IS_ERR(subdir))
1001 goto found;
1002 if (PTR_ERR(subdir) != -ENOENT)
1003 goto failed;
1004
1005 spin_unlock(&sysctl_lock);
1006 new = new_dir(set, name, namelen);
1007 spin_lock(&sysctl_lock);
1008 subdir = ERR_PTR(-ENOMEM);
1009 if (!new)
1010 goto failed;
1011
1012 /* Was the subdir added while we dropped the lock? */
1013 subdir = find_subdir(dir, name, namelen);
1014 if (!IS_ERR(subdir))
1015 goto found;
1016 if (PTR_ERR(subdir) != -ENOENT)
1017 goto failed;
1018
1019 /* Nope. Use the our freshly made directory entry. */
1020 err = insert_header(dir, &new->header);
1021 subdir = ERR_PTR(err);
1022 if (err)
1023 goto failed;
1024 subdir = new;
1025found:
1026 subdir->header.nreg++;
1027failed:
1028 if (IS_ERR(subdir)) {
1029 pr_err("sysctl could not get directory: ");
1030 sysctl_print_dir(dir);
1031 pr_cont("%*.*s %ld\n", namelen, namelen, name,
1032 PTR_ERR(subdir));
1033 }
1034 drop_sysctl_table(&dir->header);
1035 if (new)
1036 drop_sysctl_table(&new->header);
1037 spin_unlock(&sysctl_lock);
1038 return subdir;
1039}
1040
1041static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
1042{
1043 struct ctl_dir *parent;
1044 const char *procname;
1045 if (!dir->header.parent)
1046 return &set->dir;
1047 parent = xlate_dir(set, dir->header.parent);
1048 if (IS_ERR(parent))
1049 return parent;
1050 procname = dir->header.ctl_table[0].procname;
1051 return find_subdir(parent, procname, strlen(procname));
1052}
1053
1054static int sysctl_follow_link(struct ctl_table_header **phead,
1055 const struct ctl_table **pentry)
1056{
1057 struct ctl_table_header *head;
1058 const struct ctl_table *entry;
1059 struct ctl_table_root *root;
1060 struct ctl_table_set *set;
1061 struct ctl_dir *dir;
1062 int ret;
1063
1064 spin_lock(&sysctl_lock);
1065 root = (*pentry)->data;
1066 set = lookup_header_set(root);
1067 dir = xlate_dir(set, (*phead)->parent);
1068 if (IS_ERR(dir))
1069 ret = PTR_ERR(dir);
1070 else {
1071 const char *procname = (*pentry)->procname;
1072 head = NULL;
1073 entry = find_entry(&head, dir, procname, strlen(procname));
1074 ret = -ENOENT;
1075 if (entry && use_table(head)) {
1076 unuse_table(*phead);
1077 *phead = head;
1078 *pentry = entry;
1079 ret = 0;
1080 }
1081 }
1082
1083 spin_unlock(&sysctl_lock);
1084 return ret;
1085}
1086
1087static int sysctl_err(const char *path, const struct ctl_table *table, char *fmt, ...)
1088{
1089 struct va_format vaf;
1090 va_list args;
1091
1092 va_start(args, fmt);
1093 vaf.fmt = fmt;
1094 vaf.va = &args;
1095
1096 pr_err("sysctl table check failed: %s/%s %pV\n",
1097 path, table->procname, &vaf);
1098
1099 va_end(args);
1100 return -EINVAL;
1101}
1102
1103static int sysctl_check_table_array(const char *path, const struct ctl_table *table)
1104{
1105 unsigned int extra;
1106 int err = 0;
1107
1108 if ((table->proc_handler == proc_douintvec) ||
1109 (table->proc_handler == proc_douintvec_minmax)) {
1110 if (table->maxlen != sizeof(unsigned int))
1111 err |= sysctl_err(path, table, "array not allowed");
1112 }
1113
1114 if (table->proc_handler == proc_dou8vec_minmax) {
1115 if (table->maxlen != sizeof(u8))
1116 err |= sysctl_err(path, table, "array not allowed");
1117
1118 if (table->extra1) {
1119 extra = *(unsigned int *) table->extra1;
1120 if (extra > 255U)
1121 err |= sysctl_err(path, table,
1122 "range value too large for proc_dou8vec_minmax");
1123 }
1124 if (table->extra2) {
1125 extra = *(unsigned int *) table->extra2;
1126 if (extra > 255U)
1127 err |= sysctl_err(path, table,
1128 "range value too large for proc_dou8vec_minmax");
1129 }
1130 }
1131
1132 if (table->proc_handler == proc_dobool) {
1133 if (table->maxlen != sizeof(bool))
1134 err |= sysctl_err(path, table, "array not allowed");
1135 }
1136
1137 return err;
1138}
1139
1140static int sysctl_check_table(const char *path, struct ctl_table_header *header)
1141{
1142 const struct ctl_table *entry;
1143 int err = 0;
1144 list_for_each_table_entry(entry, header) {
1145 if (!entry->procname)
1146 err |= sysctl_err(path, entry, "procname is null");
1147 if ((entry->proc_handler == proc_dostring) ||
1148 (entry->proc_handler == proc_dobool) ||
1149 (entry->proc_handler == proc_dointvec) ||
1150 (entry->proc_handler == proc_douintvec) ||
1151 (entry->proc_handler == proc_douintvec_minmax) ||
1152 (entry->proc_handler == proc_dointvec_minmax) ||
1153 (entry->proc_handler == proc_dou8vec_minmax) ||
1154 (entry->proc_handler == proc_dointvec_jiffies) ||
1155 (entry->proc_handler == proc_dointvec_userhz_jiffies) ||
1156 (entry->proc_handler == proc_dointvec_ms_jiffies) ||
1157 (entry->proc_handler == proc_doulongvec_minmax) ||
1158 (entry->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1159 if (!entry->data)
1160 err |= sysctl_err(path, entry, "No data");
1161 if (!entry->maxlen)
1162 err |= sysctl_err(path, entry, "No maxlen");
1163 else
1164 err |= sysctl_check_table_array(path, entry);
1165 }
1166 if (!entry->proc_handler)
1167 err |= sysctl_err(path, entry, "No proc_handler");
1168
1169 if ((entry->mode & (S_IRUGO|S_IWUGO)) != entry->mode)
1170 err |= sysctl_err(path, entry, "bogus .mode 0%o",
1171 entry->mode);
1172 }
1173 return err;
1174}
1175
1176static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_header *head)
1177{
1178 struct ctl_table *link_table, *link;
1179 struct ctl_table_header *links;
1180 const struct ctl_table *entry;
1181 struct ctl_node *node;
1182 char *link_name;
1183 int name_bytes;
1184
1185 name_bytes = 0;
1186 list_for_each_table_entry(entry, head) {
1187 name_bytes += strlen(entry->procname) + 1;
1188 }
1189
1190 links = kzalloc(sizeof(struct ctl_table_header) +
1191 sizeof(struct ctl_node)*head->ctl_table_size +
1192 sizeof(struct ctl_table)*head->ctl_table_size +
1193 name_bytes,
1194 GFP_KERNEL);
1195
1196 if (!links)
1197 return NULL;
1198
1199 node = (struct ctl_node *)(links + 1);
1200 link_table = (struct ctl_table *)(node + head->ctl_table_size);
1201 link_name = (char *)(link_table + head->ctl_table_size);
1202 link = link_table;
1203
1204 list_for_each_table_entry(entry, head) {
1205 int len = strlen(entry->procname) + 1;
1206 memcpy(link_name, entry->procname, len);
1207 link->procname = link_name;
1208 link->mode = S_IFLNK|S_IRWXUGO;
1209 link->data = head->root;
1210 link_name += len;
1211 link++;
1212 }
1213 init_header(links, dir->header.root, dir->header.set, node, link_table,
1214 head->ctl_table_size);
1215 links->nreg = head->ctl_table_size;
1216
1217 return links;
1218}
1219
1220static bool get_links(struct ctl_dir *dir,
1221 struct ctl_table_header *header,
1222 struct ctl_table_root *link_root)
1223{
1224 struct ctl_table_header *tmp_head;
1225 const struct ctl_table *entry, *link;
1226
1227 if (header->ctl_table_size == 0 ||
1228 sysctl_is_perm_empty_ctl_header(header))
1229 return true;
1230
1231 /* Are there links available for every entry in table? */
1232 list_for_each_table_entry(entry, header) {
1233 const char *procname = entry->procname;
1234 link = find_entry(&tmp_head, dir, procname, strlen(procname));
1235 if (!link)
1236 return false;
1237 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1238 continue;
1239 if (S_ISLNK(link->mode) && (link->data == link_root))
1240 continue;
1241 return false;
1242 }
1243
1244 /* The checks passed. Increase the registration count on the links */
1245 list_for_each_table_entry(entry, header) {
1246 const char *procname = entry->procname;
1247 link = find_entry(&tmp_head, dir, procname, strlen(procname));
1248 tmp_head->nreg++;
1249 }
1250 return true;
1251}
1252
1253static int insert_links(struct ctl_table_header *head)
1254{
1255 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1256 struct ctl_dir *core_parent;
1257 struct ctl_table_header *links;
1258 int err;
1259
1260 if (head->set == root_set)
1261 return 0;
1262
1263 core_parent = xlate_dir(root_set, head->parent);
1264 if (IS_ERR(core_parent))
1265 return 0;
1266
1267 if (get_links(core_parent, head, head->root))
1268 return 0;
1269
1270 core_parent->header.nreg++;
1271 spin_unlock(&sysctl_lock);
1272
1273 links = new_links(core_parent, head);
1274
1275 spin_lock(&sysctl_lock);
1276 err = -ENOMEM;
1277 if (!links)
1278 goto out;
1279
1280 err = 0;
1281 if (get_links(core_parent, head, head->root)) {
1282 kfree(links);
1283 goto out;
1284 }
1285
1286 err = insert_header(core_parent, links);
1287 if (err)
1288 kfree(links);
1289out:
1290 drop_sysctl_table(&core_parent->header);
1291 return err;
1292}
1293
1294/* Find the directory for the ctl_table. If one is not found create it. */
1295static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)
1296{
1297 const char *name, *nextname;
1298
1299 for (name = path; name; name = nextname) {
1300 int namelen;
1301 nextname = strchr(name, '/');
1302 if (nextname) {
1303 namelen = nextname - name;
1304 nextname++;
1305 } else {
1306 namelen = strlen(name);
1307 }
1308 if (namelen == 0)
1309 continue;
1310
1311 /*
1312 * namelen ensures if name is "foo/bar/yay" only foo is
1313 * registered first. We traverse as if using mkdir -p and
1314 * return a ctl_dir for the last directory entry.
1315 */
1316 dir = get_subdir(dir, name, namelen);
1317 if (IS_ERR(dir))
1318 break;
1319 }
1320 return dir;
1321}
1322
1323/**
1324 * __register_sysctl_table - register a leaf sysctl table
1325 * @set: Sysctl tree to register on
1326 * @path: The path to the directory the sysctl table is in.
1327 *
1328 * @table: the top-level table structure. This table should not be free'd
1329 * after registration. So it should not be used on stack. It can either
1330 * be a global or dynamically allocated by the caller and free'd later
1331 * after sysctl unregistration.
1332 * @table_size : The number of elements in table
1333 *
1334 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1335 * array.
1336 *
1337 * The members of the &struct ctl_table structure are used as follows:
1338 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1339 * enter a sysctl file
1340 * data - a pointer to data for use by proc_handler
1341 * maxlen - the maximum size in bytes of the data
1342 * mode - the file permissions for the /proc/sys file
1343 * type - Defines the target type (described in struct definition)
1344 * proc_handler - the text handler routine (described below)
1345 *
1346 * extra1, extra2 - extra pointers usable by the proc handler routines
1347 * XXX: we should eventually modify these to use long min / max [0]
1348 * [0] https://lkml.kernel.org/87zgpte9o4.fsf@email.froward.int.ebiederm.org
1349 *
1350 * Leaf nodes in the sysctl tree will be represented by a single file
1351 * under /proc; non-leaf nodes are not allowed.
1352 *
1353 * There must be a proc_handler routine for any terminal nodes.
1354 * Several default handlers are available to cover common cases -
1355 *
1356 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1357 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1358 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1359 *
1360 * It is the handler's job to read the input buffer from user memory
1361 * and process it. The handler should return 0 on success.
1362 *
1363 * This routine returns %NULL on a failure to register, and a pointer
1364 * to the table header on success.
1365 */
1366struct ctl_table_header *__register_sysctl_table(
1367 struct ctl_table_set *set,
1368 const char *path, const struct ctl_table *table, size_t table_size)
1369{
1370 struct ctl_table_root *root = set->dir.header.root;
1371 struct ctl_table_header *header;
1372 struct ctl_dir *dir;
1373 struct ctl_node *node;
1374
1375 header = kzalloc(sizeof(struct ctl_table_header) +
1376 sizeof(struct ctl_node)*table_size, GFP_KERNEL_ACCOUNT);
1377 if (!header)
1378 return NULL;
1379
1380 node = (struct ctl_node *)(header + 1);
1381 init_header(header, root, set, node, table, table_size);
1382 if (sysctl_check_table(path, header))
1383 goto fail;
1384
1385 spin_lock(&sysctl_lock);
1386 dir = &set->dir;
1387 /* Reference moved down the directory tree get_subdir */
1388 dir->header.nreg++;
1389 spin_unlock(&sysctl_lock);
1390
1391 dir = sysctl_mkdir_p(dir, path);
1392 if (IS_ERR(dir))
1393 goto fail;
1394 spin_lock(&sysctl_lock);
1395 if (insert_header(dir, header))
1396 goto fail_put_dir_locked;
1397
1398 drop_sysctl_table(&dir->header);
1399 spin_unlock(&sysctl_lock);
1400
1401 return header;
1402
1403fail_put_dir_locked:
1404 drop_sysctl_table(&dir->header);
1405 spin_unlock(&sysctl_lock);
1406fail:
1407 kfree(header);
1408 return NULL;
1409}
1410
1411/**
1412 * register_sysctl_sz - register a sysctl table
1413 * @path: The path to the directory the sysctl table is in. If the path
1414 * doesn't exist we will create it for you.
1415 * @table: the table structure. The calller must ensure the life of the @table
1416 * will be kept during the lifetime use of the syctl. It must not be freed
1417 * until unregister_sysctl_table() is called with the given returned table
1418 * with this registration. If your code is non modular then you don't need
1419 * to call unregister_sysctl_table() and can instead use something like
1420 * register_sysctl_init() which does not care for the result of the syctl
1421 * registration.
1422 * @table_size: The number of elements in table.
1423 *
1424 * Register a sysctl table. @table should be a filled in ctl_table
1425 * array. A completely 0 filled entry terminates the table.
1426 *
1427 * See __register_sysctl_table for more details.
1428 */
1429struct ctl_table_header *register_sysctl_sz(const char *path, const struct ctl_table *table,
1430 size_t table_size)
1431{
1432 return __register_sysctl_table(&sysctl_table_root.default_set,
1433 path, table, table_size);
1434}
1435EXPORT_SYMBOL(register_sysctl_sz);
1436
1437/**
1438 * __register_sysctl_init() - register sysctl table to path
1439 * @path: path name for sysctl base. If that path doesn't exist we will create
1440 * it for you.
1441 * @table: This is the sysctl table that needs to be registered to the path.
1442 * The caller must ensure the life of the @table will be kept during the
1443 * lifetime use of the sysctl.
1444 * @table_name: The name of sysctl table, only used for log printing when
1445 * registration fails
1446 * @table_size: The number of elements in table
1447 *
1448 * The sysctl interface is used by userspace to query or modify at runtime
1449 * a predefined value set on a variable. These variables however have default
1450 * values pre-set. Code which depends on these variables will always work even
1451 * if register_sysctl() fails. If register_sysctl() fails you'd just loose the
1452 * ability to query or modify the sysctls dynamically at run time. Chances of
1453 * register_sysctl() failing on init are extremely low, and so for both reasons
1454 * this function does not return any error as it is used by initialization code.
1455 *
1456 * Context: if your base directory does not exist it will be created for you.
1457 */
1458void __init __register_sysctl_init(const char *path, const struct ctl_table *table,
1459 const char *table_name, size_t table_size)
1460{
1461 struct ctl_table_header *hdr = register_sysctl_sz(path, table, table_size);
1462
1463 if (unlikely(!hdr)) {
1464 pr_err("failed when register_sysctl_sz %s to %s\n", table_name, path);
1465 return;
1466 }
1467 kmemleak_not_leak(hdr);
1468}
1469
1470static void put_links(struct ctl_table_header *header)
1471{
1472 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1473 struct ctl_table_root *root = header->root;
1474 struct ctl_dir *parent = header->parent;
1475 struct ctl_dir *core_parent;
1476 const struct ctl_table *entry;
1477
1478 if (header->set == root_set)
1479 return;
1480
1481 core_parent = xlate_dir(root_set, parent);
1482 if (IS_ERR(core_parent))
1483 return;
1484
1485 list_for_each_table_entry(entry, header) {
1486 struct ctl_table_header *link_head;
1487 const struct ctl_table *link;
1488 const char *name = entry->procname;
1489
1490 link = find_entry(&link_head, core_parent, name, strlen(name));
1491 if (link &&
1492 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1493 (S_ISLNK(link->mode) && (link->data == root)))) {
1494 drop_sysctl_table(link_head);
1495 }
1496 else {
1497 pr_err("sysctl link missing during unregister: ");
1498 sysctl_print_dir(parent);
1499 pr_cont("%s\n", name);
1500 }
1501 }
1502}
1503
1504static void drop_sysctl_table(struct ctl_table_header *header)
1505{
1506 struct ctl_dir *parent = header->parent;
1507
1508 if (--header->nreg)
1509 return;
1510
1511 if (parent) {
1512 put_links(header);
1513 start_unregistering(header);
1514 }
1515
1516 if (!--header->count)
1517 kfree_rcu(header, rcu);
1518
1519 if (parent)
1520 drop_sysctl_table(&parent->header);
1521}
1522
1523/**
1524 * unregister_sysctl_table - unregister a sysctl table hierarchy
1525 * @header: the header returned from register_sysctl or __register_sysctl_table
1526 *
1527 * Unregisters the sysctl table and all children. proc entries may not
1528 * actually be removed until they are no longer used by anyone.
1529 */
1530void unregister_sysctl_table(struct ctl_table_header * header)
1531{
1532 might_sleep();
1533
1534 if (header == NULL)
1535 return;
1536
1537 spin_lock(&sysctl_lock);
1538 drop_sysctl_table(header);
1539 spin_unlock(&sysctl_lock);
1540}
1541EXPORT_SYMBOL(unregister_sysctl_table);
1542
1543void setup_sysctl_set(struct ctl_table_set *set,
1544 struct ctl_table_root *root,
1545 int (*is_seen)(struct ctl_table_set *))
1546{
1547 memset(set, 0, sizeof(*set));
1548 set->is_seen = is_seen;
1549 init_header(&set->dir.header, root, set, NULL, root_table, 1);
1550}
1551
1552void retire_sysctl_set(struct ctl_table_set *set)
1553{
1554 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1555}
1556
1557int __init proc_sys_init(void)
1558{
1559 struct proc_dir_entry *proc_sys_root;
1560
1561 proc_sys_root = proc_mkdir("sys", NULL);
1562 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1563 proc_sys_root->proc_dir_ops = &proc_sys_dir_file_operations;
1564 proc_sys_root->nlink = 0;
1565
1566 return sysctl_init_bases();
1567}
1568
1569struct sysctl_alias {
1570 const char *kernel_param;
1571 const char *sysctl_param;
1572};
1573
1574/*
1575 * Historically some settings had both sysctl and a command line parameter.
1576 * With the generic sysctl. parameter support, we can handle them at a single
1577 * place and only keep the historical name for compatibility. This is not meant
1578 * to add brand new aliases. When adding existing aliases, consider whether
1579 * the possibly different moment of changing the value (e.g. from early_param
1580 * to the moment do_sysctl_args() is called) is an issue for the specific
1581 * parameter.
1582 */
1583static const struct sysctl_alias sysctl_aliases[] = {
1584 {"hardlockup_all_cpu_backtrace", "kernel.hardlockup_all_cpu_backtrace" },
1585 {"hung_task_panic", "kernel.hung_task_panic" },
1586 {"numa_zonelist_order", "vm.numa_zonelist_order" },
1587 {"softlockup_all_cpu_backtrace", "kernel.softlockup_all_cpu_backtrace" },
1588 { }
1589};
1590
1591static const char *sysctl_find_alias(char *param)
1592{
1593 const struct sysctl_alias *alias;
1594
1595 for (alias = &sysctl_aliases[0]; alias->kernel_param != NULL; alias++) {
1596 if (strcmp(alias->kernel_param, param) == 0)
1597 return alias->sysctl_param;
1598 }
1599
1600 return NULL;
1601}
1602
1603bool sysctl_is_alias(char *param)
1604{
1605 const char *alias = sysctl_find_alias(param);
1606
1607 return alias != NULL;
1608}
1609
1610/* Set sysctl value passed on kernel command line. */
1611static int process_sysctl_arg(char *param, char *val,
1612 const char *unused, void *arg)
1613{
1614 char *path;
1615 struct vfsmount **proc_mnt = arg;
1616 struct file_system_type *proc_fs_type;
1617 struct file *file;
1618 int len;
1619 int err;
1620 loff_t pos = 0;
1621 ssize_t wret;
1622
1623 if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {
1624 param += sizeof("sysctl") - 1;
1625
1626 if (param[0] != '/' && param[0] != '.')
1627 return 0;
1628
1629 param++;
1630 } else {
1631 param = (char *) sysctl_find_alias(param);
1632 if (!param)
1633 return 0;
1634 }
1635
1636 if (!val)
1637 return -EINVAL;
1638 len = strlen(val);
1639 if (len == 0)
1640 return -EINVAL;
1641
1642 /*
1643 * To set sysctl options, we use a temporary mount of proc, look up the
1644 * respective sys/ file and write to it. To avoid mounting it when no
1645 * options were given, we mount it only when the first sysctl option is
1646 * found. Why not a persistent mount? There are problems with a
1647 * persistent mount of proc in that it forces userspace not to use any
1648 * proc mount options.
1649 */
1650 if (!*proc_mnt) {
1651 proc_fs_type = get_fs_type("proc");
1652 if (!proc_fs_type) {
1653 pr_err("Failed to find procfs to set sysctl from command line\n");
1654 return 0;
1655 }
1656 *proc_mnt = kern_mount(proc_fs_type);
1657 put_filesystem(proc_fs_type);
1658 if (IS_ERR(*proc_mnt)) {
1659 pr_err("Failed to mount procfs to set sysctl from command line\n");
1660 return 0;
1661 }
1662 }
1663
1664 path = kasprintf(GFP_KERNEL, "sys/%s", param);
1665 if (!path)
1666 panic("%s: Failed to allocate path for %s\n", __func__, param);
1667 strreplace(path, '.', '/');
1668
1669 file = file_open_root_mnt(*proc_mnt, path, O_WRONLY, 0);
1670 if (IS_ERR(file)) {
1671 err = PTR_ERR(file);
1672 if (err == -ENOENT)
1673 pr_err("Failed to set sysctl parameter '%s=%s': parameter not found\n",
1674 param, val);
1675 else if (err == -EACCES)
1676 pr_err("Failed to set sysctl parameter '%s=%s': permission denied (read-only?)\n",
1677 param, val);
1678 else
1679 pr_err("Error %pe opening proc file to set sysctl parameter '%s=%s'\n",
1680 file, param, val);
1681 goto out;
1682 }
1683 wret = kernel_write(file, val, len, &pos);
1684 if (wret < 0) {
1685 err = wret;
1686 if (err == -EINVAL)
1687 pr_err("Failed to set sysctl parameter '%s=%s': invalid value\n",
1688 param, val);
1689 else
1690 pr_err("Error %pe writing to proc file to set sysctl parameter '%s=%s'\n",
1691 ERR_PTR(err), param, val);
1692 } else if (wret != len) {
1693 pr_err("Wrote only %zd bytes of %d writing to proc file %s to set sysctl parameter '%s=%s\n",
1694 wret, len, path, param, val);
1695 }
1696
1697 err = filp_close(file, NULL);
1698 if (err)
1699 pr_err("Error %pe closing proc file to set sysctl parameter '%s=%s\n",
1700 ERR_PTR(err), param, val);
1701out:
1702 kfree(path);
1703 return 0;
1704}
1705
1706void do_sysctl_args(void)
1707{
1708 char *command_line;
1709 struct vfsmount *proc_mnt = NULL;
1710
1711 command_line = kstrdup(saved_command_line, GFP_KERNEL);
1712 if (!command_line)
1713 panic("%s: Failed to allocate copy of command line\n", __func__);
1714
1715 parse_args("Setting sysctl args", command_line,
1716 NULL, 0, -1, -1, &proc_mnt, process_sysctl_arg);
1717
1718 if (proc_mnt)
1719 kern_unmount(proc_mnt);
1720
1721 kfree(command_line);
1722}