4 #include <linux/init.h>
5 #include <linux/sysctl.h>
6 #include <linux/poll.h>
7 #include <linux/proc_fs.h>
8 #include <linux/printk.h>
9 #include <linux/security.h>
10 #include <linux/sched.h>
11 #include <linux/cred.h>
12 #include <linux/namei.h>
14 #include <linux/module.h>
17 static const struct dentry_operations proc_sys_dentry_operations;
18 static const struct file_operations proc_sys_file_operations;
19 static const struct inode_operations proc_sys_inode_operations;
20 static const struct file_operations proc_sys_dir_file_operations;
21 static const struct inode_operations proc_sys_dir_operations;
23 /* Support for permanently empty directories */
25 struct ctl_table sysctl_mount_point[] = {
29 static bool is_empty_dir(struct ctl_table_header *head)
31 return head->ctl_table[0].child == sysctl_mount_point;
34 static void set_empty_dir(struct ctl_dir *dir)
36 dir->header.ctl_table[0].child = sysctl_mount_point;
39 static void clear_empty_dir(struct ctl_dir *dir)
42 dir->header.ctl_table[0].child = NULL;
45 void proc_sys_poll_notify(struct ctl_table_poll *poll)
50 atomic_inc(&poll->event);
51 wake_up_interruptible(&poll->wait);
54 static struct ctl_table root_table[] = {
57 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
61 static struct ctl_table_root sysctl_table_root = {
62 .default_set.dir.header = {
65 .ctl_table = root_table }},
66 .ctl_table_arg = root_table,
67 .root = &sysctl_table_root,
68 .set = &sysctl_table_root.default_set,
72 static DEFINE_SPINLOCK(sysctl_lock);
74 static void drop_sysctl_table(struct ctl_table_header *header);
75 static int sysctl_follow_link(struct ctl_table_header **phead,
76 struct ctl_table **pentry);
77 static int insert_links(struct ctl_table_header *head);
78 static void put_links(struct ctl_table_header *header);
80 static void sysctl_print_dir(struct ctl_dir *dir)
82 if (dir->header.parent)
83 sysctl_print_dir(dir->header.parent);
84 pr_cont("%s/", dir->header.ctl_table[0].procname);
87 static int namecmp(const char *name1, int len1, const char *name2, int len2)
96 cmp = memcmp(name1, name2, minlen);
102 /* Called under sysctl_lock */
103 static struct ctl_table *find_entry(struct ctl_table_header **phead,
104 struct ctl_dir *dir, const char *name, int namelen)
106 struct ctl_table_header *head;
107 struct ctl_table *entry;
108 struct rb_node *node = dir->root.rb_node;
112 struct ctl_node *ctl_node;
113 const char *procname;
116 ctl_node = rb_entry(node, struct ctl_node, node);
117 head = ctl_node->header;
118 entry = &head->ctl_table[ctl_node - head->node];
119 procname = entry->procname;
121 cmp = namecmp(name, namelen, procname, strlen(procname));
123 node = node->rb_left;
125 node = node->rb_right;
134 static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
136 struct rb_node *node = &head->node[entry - head->ctl_table].node;
137 struct rb_node **p = &head->parent->root.rb_node;
138 struct rb_node *parent = NULL;
139 const char *name = entry->procname;
140 int namelen = strlen(name);
143 struct ctl_table_header *parent_head;
144 struct ctl_table *parent_entry;
145 struct ctl_node *parent_node;
146 const char *parent_name;
150 parent_node = rb_entry(parent, struct ctl_node, node);
151 parent_head = parent_node->header;
152 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
153 parent_name = parent_entry->procname;
155 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
161 pr_err("sysctl duplicate entry: ");
162 sysctl_print_dir(head->parent);
163 pr_cont("/%s\n", entry->procname);
168 rb_link_node(node, parent, p);
169 rb_insert_color(node, &head->parent->root);
173 static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
175 struct rb_node *node = &head->node[entry - head->ctl_table].node;
177 rb_erase(node, &head->parent->root);
180 static void init_header(struct ctl_table_header *head,
181 struct ctl_table_root *root, struct ctl_table_set *set,
182 struct ctl_node *node, struct ctl_table *table)
184 head->ctl_table = table;
185 head->ctl_table_arg = table;
189 head->unregistering = NULL;
194 INIT_HLIST_HEAD(&head->inodes);
196 struct ctl_table *entry;
197 for (entry = table; entry->procname; entry++, node++)
202 static void erase_header(struct ctl_table_header *head)
204 struct ctl_table *entry;
205 for (entry = head->ctl_table; entry->procname; entry++)
206 erase_entry(head, entry);
209 static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
211 struct ctl_table *entry;
214 /* Is this a permanently empty directory? */
215 if (is_empty_dir(&dir->header))
218 /* Am I creating a permanently empty directory? */
219 if (header->ctl_table == sysctl_mount_point) {
220 if (!RB_EMPTY_ROOT(&dir->root))
226 header->parent = dir;
227 err = insert_links(header);
230 for (entry = header->ctl_table; entry->procname; entry++) {
231 err = insert_entry(header, entry);
237 erase_header(header);
240 if (header->ctl_table == sysctl_mount_point)
241 clear_empty_dir(dir);
242 header->parent = NULL;
243 drop_sysctl_table(&dir->header);
247 /* called under sysctl_lock */
248 static int use_table(struct ctl_table_header *p)
250 if (unlikely(p->unregistering))
256 /* called under sysctl_lock */
257 static void unuse_table(struct ctl_table_header *p)
260 if (unlikely(p->unregistering))
261 complete(p->unregistering);
264 static void proc_sys_prune_dcache(struct ctl_table_header *head)
267 struct proc_inode *ei;
268 struct hlist_node *node;
269 struct super_block *sb;
273 node = hlist_first_rcu(&head->inodes);
276 ei = hlist_entry(node, struct proc_inode, sysctl_inodes);
277 spin_lock(&sysctl_lock);
278 hlist_del_init_rcu(&ei->sysctl_inodes);
279 spin_unlock(&sysctl_lock);
281 inode = &ei->vfs_inode;
283 if (!atomic_inc_not_zero(&sb->s_active))
285 inode = igrab(inode);
287 if (unlikely(!inode)) {
288 deactivate_super(sb);
293 d_prune_aliases(inode);
295 deactivate_super(sb);
302 /* called under sysctl_lock, will reacquire if has to wait */
303 static void start_unregistering(struct ctl_table_header *p)
306 * if p->used is 0, nobody will ever touch that entry again;
307 * we'll eliminate all paths to it before dropping sysctl_lock
309 if (unlikely(p->used)) {
310 struct completion wait;
311 init_completion(&wait);
312 p->unregistering = &wait;
313 spin_unlock(&sysctl_lock);
314 wait_for_completion(&wait);
316 /* anything non-NULL; we'll never dereference it */
317 p->unregistering = ERR_PTR(-EINVAL);
318 spin_unlock(&sysctl_lock);
321 * Prune dentries for unregistered sysctls: namespaced sysctls
322 * can have duplicate names and contaminate dcache very badly.
324 proc_sys_prune_dcache(p);
326 * do not remove from the list until nobody holds it; walking the
327 * list in do_sysctl() relies on that.
329 spin_lock(&sysctl_lock);
333 static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
336 spin_lock(&sysctl_lock);
337 if (!use_table(head))
338 head = ERR_PTR(-ENOENT);
339 spin_unlock(&sysctl_lock);
343 static void sysctl_head_finish(struct ctl_table_header *head)
347 spin_lock(&sysctl_lock);
349 spin_unlock(&sysctl_lock);
352 static struct ctl_table_set *
353 lookup_header_set(struct ctl_table_root *root)
355 struct ctl_table_set *set = &root->default_set;
357 set = root->lookup(root);
361 static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
363 const char *name, int namelen)
365 struct ctl_table_header *head;
366 struct ctl_table *entry;
368 spin_lock(&sysctl_lock);
369 entry = find_entry(&head, dir, name, namelen);
370 if (entry && use_table(head))
374 spin_unlock(&sysctl_lock);
378 static struct ctl_node *first_usable_entry(struct rb_node *node)
380 struct ctl_node *ctl_node;
382 for (;node; node = rb_next(node)) {
383 ctl_node = rb_entry(node, struct ctl_node, node);
384 if (use_table(ctl_node->header))
390 static void first_entry(struct ctl_dir *dir,
391 struct ctl_table_header **phead, struct ctl_table **pentry)
393 struct ctl_table_header *head = NULL;
394 struct ctl_table *entry = NULL;
395 struct ctl_node *ctl_node;
397 spin_lock(&sysctl_lock);
398 ctl_node = first_usable_entry(rb_first(&dir->root));
399 spin_unlock(&sysctl_lock);
401 head = ctl_node->header;
402 entry = &head->ctl_table[ctl_node - head->node];
408 static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
410 struct ctl_table_header *head = *phead;
411 struct ctl_table *entry = *pentry;
412 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
414 spin_lock(&sysctl_lock);
417 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
418 spin_unlock(&sysctl_lock);
421 head = ctl_node->header;
422 entry = &head->ctl_table[ctl_node - head->node];
429 * sysctl_perm does NOT grant the superuser all rights automatically, because
430 * some sysctl variables are readonly even to root.
433 static int test_perm(int mode, int op)
435 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
437 else if (in_egroup_p(GLOBAL_ROOT_GID))
439 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
444 static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
446 struct ctl_table_root *root = head->root;
449 if (root->permissions)
450 mode = root->permissions(head, table);
454 return test_perm(mode, op);
457 static struct inode *proc_sys_make_inode(struct super_block *sb,
458 struct ctl_table_header *head, struct ctl_table *table)
460 struct ctl_table_root *root = head->root;
462 struct proc_inode *ei;
464 inode = new_inode(sb);
468 inode->i_ino = get_next_ino();
472 spin_lock(&sysctl_lock);
473 if (unlikely(head->unregistering)) {
474 spin_unlock(&sysctl_lock);
480 ei->sysctl_entry = table;
481 hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes);
483 spin_unlock(&sysctl_lock);
485 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
486 inode->i_mode = table->mode;
487 if (!S_ISDIR(table->mode)) {
488 inode->i_mode |= S_IFREG;
489 inode->i_op = &proc_sys_inode_operations;
490 inode->i_fop = &proc_sys_file_operations;
492 inode->i_mode |= S_IFDIR;
493 inode->i_op = &proc_sys_dir_operations;
494 inode->i_fop = &proc_sys_dir_file_operations;
495 if (is_empty_dir(head))
496 make_empty_dir_inode(inode);
499 if (root->set_ownership)
500 root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
506 void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
508 spin_lock(&sysctl_lock);
509 hlist_del_init_rcu(&PROC_I(inode)->sysctl_inodes);
511 kfree_rcu(head, rcu);
512 spin_unlock(&sysctl_lock);
515 static struct ctl_table_header *grab_header(struct inode *inode)
517 struct ctl_table_header *head = PROC_I(inode)->sysctl;
519 head = &sysctl_table_root.default_set.dir.header;
520 return sysctl_head_grab(head);
523 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
526 struct ctl_table_header *head = grab_header(dir);
527 struct ctl_table_header *h = NULL;
528 const struct qstr *name = &dentry->d_name;
531 struct dentry *err = ERR_PTR(-ENOENT);
532 struct ctl_dir *ctl_dir;
536 return ERR_CAST(head);
538 ctl_dir = container_of(head, struct ctl_dir, header);
540 p = lookup_entry(&h, ctl_dir, name->name, name->len);
544 if (S_ISLNK(p->mode)) {
545 ret = sysctl_follow_link(&h, &p);
551 err = ERR_PTR(-ENOMEM);
552 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
557 d_set_d_op(dentry, &proc_sys_dentry_operations);
558 d_add(dentry, inode);
562 sysctl_head_finish(h);
563 sysctl_head_finish(head);
567 static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
568 size_t count, loff_t *ppos, int write)
570 struct inode *inode = file_inode(filp);
571 struct ctl_table_header *head = grab_header(inode);
572 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
577 return PTR_ERR(head);
580 * At this point we know that the sysctl was not unregistered
581 * and won't be until we finish.
584 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
587 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
589 if (!table->proc_handler)
592 /* careful: calling conventions are nasty here */
594 error = table->proc_handler(table, write, buf, &res, ppos);
598 sysctl_head_finish(head);
603 static ssize_t proc_sys_read(struct file *filp, char __user *buf,
604 size_t count, loff_t *ppos)
606 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
609 static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
610 size_t count, loff_t *ppos)
612 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
615 static int proc_sys_open(struct inode *inode, struct file *filp)
617 struct ctl_table_header *head = grab_header(inode);
618 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
620 /* sysctl was unregistered */
622 return PTR_ERR(head);
625 filp->private_data = proc_sys_poll_event(table->poll);
627 sysctl_head_finish(head);
632 static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
634 struct inode *inode = file_inode(filp);
635 struct ctl_table_header *head = grab_header(inode);
636 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
637 unsigned int ret = DEFAULT_POLLMASK;
640 /* sysctl was unregistered */
642 return POLLERR | POLLHUP;
644 if (!table->proc_handler)
650 event = (unsigned long)filp->private_data;
651 poll_wait(filp, &table->poll->wait, wait);
653 if (event != atomic_read(&table->poll->event)) {
654 filp->private_data = proc_sys_poll_event(table->poll);
655 ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI;
659 sysctl_head_finish(head);
664 static bool proc_sys_fill_cache(struct file *file,
665 struct dir_context *ctx,
666 struct ctl_table_header *head,
667 struct ctl_table *table)
669 struct dentry *child, *dir = file->f_path.dentry;
673 unsigned type = DT_UNKNOWN;
675 qname.name = table->procname;
676 qname.len = strlen(table->procname);
677 qname.hash = full_name_hash(dir, qname.name, qname.len);
679 child = d_lookup(dir, &qname);
681 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
682 child = d_alloc_parallel(dir, &qname, &wq);
685 if (d_in_lookup(child)) {
686 inode = proc_sys_make_inode(dir->d_sb, head, table);
688 d_lookup_done(child);
692 d_set_d_op(child, &proc_sys_dentry_operations);
696 inode = d_inode(child);
698 type = inode->i_mode >> 12;
700 return dir_emit(ctx, qname.name, qname.len, ino, type);
703 static bool proc_sys_link_fill_cache(struct file *file,
704 struct dir_context *ctx,
705 struct ctl_table_header *head,
706 struct ctl_table *table)
709 head = sysctl_head_grab(head);
711 if (S_ISLNK(table->mode)) {
712 /* It is not an error if we can not follow the link ignore it */
713 int err = sysctl_follow_link(&head, &table);
718 ret = proc_sys_fill_cache(file, ctx, head, table);
720 sysctl_head_finish(head);
724 static int scan(struct ctl_table_header *head, struct ctl_table *table,
725 unsigned long *pos, struct file *file,
726 struct dir_context *ctx)
730 if ((*pos)++ < ctx->pos)
733 if (unlikely(S_ISLNK(table->mode)))
734 res = proc_sys_link_fill_cache(file, ctx, head, table);
736 res = proc_sys_fill_cache(file, ctx, head, table);
744 static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
746 struct ctl_table_header *head = grab_header(file_inode(file));
747 struct ctl_table_header *h = NULL;
748 struct ctl_table *entry;
749 struct ctl_dir *ctl_dir;
753 return PTR_ERR(head);
755 ctl_dir = container_of(head, struct ctl_dir, header);
757 if (!dir_emit_dots(file, ctx))
762 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
763 if (!scan(h, entry, &pos, file, ctx)) {
764 sysctl_head_finish(h);
769 sysctl_head_finish(head);
773 static int proc_sys_permission(struct inode *inode, int mask)
776 * sysctl entries that are not writeable,
777 * are _NOT_ writeable, capabilities or not.
779 struct ctl_table_header *head;
780 struct ctl_table *table;
783 /* Executable files are not allowed under /proc/sys/ */
784 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
787 head = grab_header(inode);
789 return PTR_ERR(head);
791 table = PROC_I(inode)->sysctl_entry;
792 if (!table) /* global root - r-xr-xr-x */
793 error = mask & MAY_WRITE ? -EACCES : 0;
794 else /* Use the permissions on the sysctl table entry */
795 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
797 sysctl_head_finish(head);
801 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
803 struct inode *inode = d_inode(dentry);
806 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
809 error = setattr_prepare(dentry, attr);
813 setattr_copy(inode, attr);
814 mark_inode_dirty(inode);
818 static int proc_sys_getattr(const struct path *path, struct kstat *stat,
819 u32 request_mask, unsigned int query_flags)
821 struct inode *inode = d_inode(path->dentry);
822 struct ctl_table_header *head = grab_header(inode);
823 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
826 return PTR_ERR(head);
828 generic_fillattr(inode, stat);
830 stat->mode = (stat->mode & S_IFMT) | table->mode;
832 sysctl_head_finish(head);
836 static const struct file_operations proc_sys_file_operations = {
837 .open = proc_sys_open,
838 .poll = proc_sys_poll,
839 .read = proc_sys_read,
840 .write = proc_sys_write,
841 .llseek = default_llseek,
844 static const struct file_operations proc_sys_dir_file_operations = {
845 .read = generic_read_dir,
846 .iterate_shared = proc_sys_readdir,
847 .llseek = generic_file_llseek,
850 static const struct inode_operations proc_sys_inode_operations = {
851 .permission = proc_sys_permission,
852 .setattr = proc_sys_setattr,
853 .getattr = proc_sys_getattr,
856 static const struct inode_operations proc_sys_dir_operations = {
857 .lookup = proc_sys_lookup,
858 .permission = proc_sys_permission,
859 .setattr = proc_sys_setattr,
860 .getattr = proc_sys_getattr,
863 static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
865 if (flags & LOOKUP_RCU)
867 return !PROC_I(d_inode(dentry))->sysctl->unregistering;
870 static int proc_sys_delete(const struct dentry *dentry)
872 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
875 static int sysctl_is_seen(struct ctl_table_header *p)
877 struct ctl_table_set *set = p->set;
879 spin_lock(&sysctl_lock);
880 if (p->unregistering)
882 else if (!set->is_seen)
885 res = set->is_seen(set);
886 spin_unlock(&sysctl_lock);
890 static int proc_sys_compare(const struct dentry *dentry,
891 unsigned int len, const char *str, const struct qstr *name)
893 struct ctl_table_header *head;
896 /* Although proc doesn't have negative dentries, rcu-walk means
897 * that inode here can be NULL */
898 /* AV: can it, indeed? */
899 inode = d_inode_rcu(dentry);
902 if (name->len != len)
904 if (memcmp(name->name, str, len))
906 head = rcu_dereference(PROC_I(inode)->sysctl);
907 return !head || !sysctl_is_seen(head);
910 static const struct dentry_operations proc_sys_dentry_operations = {
911 .d_revalidate = proc_sys_revalidate,
912 .d_delete = proc_sys_delete,
913 .d_compare = proc_sys_compare,
916 static struct ctl_dir *find_subdir(struct ctl_dir *dir,
917 const char *name, int namelen)
919 struct ctl_table_header *head;
920 struct ctl_table *entry;
922 entry = find_entry(&head, dir, name, namelen);
924 return ERR_PTR(-ENOENT);
925 if (!S_ISDIR(entry->mode))
926 return ERR_PTR(-ENOTDIR);
927 return container_of(head, struct ctl_dir, header);
930 static struct ctl_dir *new_dir(struct ctl_table_set *set,
931 const char *name, int namelen)
933 struct ctl_table *table;
935 struct ctl_node *node;
938 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
939 sizeof(struct ctl_table)*2 + namelen + 1,
944 node = (struct ctl_node *)(new + 1);
945 table = (struct ctl_table *)(node + 1);
946 new_name = (char *)(table + 2);
947 memcpy(new_name, name, namelen);
948 new_name[namelen] = '\0';
949 table[0].procname = new_name;
950 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
951 init_header(&new->header, set->dir.header.root, set, node, table);
957 * get_subdir - find or create a subdir with the specified name.
958 * @dir: Directory to create the subdirectory in
959 * @name: The name of the subdirectory to find or create
960 * @namelen: The length of name
962 * Takes a directory with an elevated reference count so we know that
963 * if we drop the lock the directory will not go away. Upon success
964 * the reference is moved from @dir to the returned subdirectory.
965 * Upon error an error code is returned and the reference on @dir is
968 static struct ctl_dir *get_subdir(struct ctl_dir *dir,
969 const char *name, int namelen)
971 struct ctl_table_set *set = dir->header.set;
972 struct ctl_dir *subdir, *new = NULL;
975 spin_lock(&sysctl_lock);
976 subdir = find_subdir(dir, name, namelen);
979 if (PTR_ERR(subdir) != -ENOENT)
982 spin_unlock(&sysctl_lock);
983 new = new_dir(set, name, namelen);
984 spin_lock(&sysctl_lock);
985 subdir = ERR_PTR(-ENOMEM);
989 /* Was the subdir added while we dropped the lock? */
990 subdir = find_subdir(dir, name, namelen);
993 if (PTR_ERR(subdir) != -ENOENT)
996 /* Nope. Use the our freshly made directory entry. */
997 err = insert_header(dir, &new->header);
998 subdir = ERR_PTR(err);
1003 subdir->header.nreg++;
1005 if (IS_ERR(subdir)) {
1006 pr_err("sysctl could not get directory: ");
1007 sysctl_print_dir(dir);
1008 pr_cont("/%*.*s %ld\n",
1009 namelen, namelen, name, PTR_ERR(subdir));
1011 drop_sysctl_table(&dir->header);
1013 drop_sysctl_table(&new->header);
1014 spin_unlock(&sysctl_lock);
1018 static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
1020 struct ctl_dir *parent;
1021 const char *procname;
1022 if (!dir->header.parent)
1024 parent = xlate_dir(set, dir->header.parent);
1027 procname = dir->header.ctl_table[0].procname;
1028 return find_subdir(parent, procname, strlen(procname));
1031 static int sysctl_follow_link(struct ctl_table_header **phead,
1032 struct ctl_table **pentry)
1034 struct ctl_table_header *head;
1035 struct ctl_table_root *root;
1036 struct ctl_table_set *set;
1037 struct ctl_table *entry;
1038 struct ctl_dir *dir;
1042 spin_lock(&sysctl_lock);
1043 root = (*pentry)->data;
1044 set = lookup_header_set(root);
1045 dir = xlate_dir(set, (*phead)->parent);
1049 const char *procname = (*pentry)->procname;
1051 entry = find_entry(&head, dir, procname, strlen(procname));
1053 if (entry && use_table(head)) {
1054 unuse_table(*phead);
1061 spin_unlock(&sysctl_lock);
1065 static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
1067 struct va_format vaf;
1070 va_start(args, fmt);
1074 pr_err("sysctl table check failed: %s/%s %pV\n",
1075 path, table->procname, &vaf);
1081 static int sysctl_check_table_array(const char *path, struct ctl_table *table)
1085 if ((table->proc_handler == proc_douintvec) ||
1086 (table->proc_handler == proc_douintvec_minmax)) {
1087 if (table->maxlen != sizeof(unsigned int))
1088 err |= sysctl_err(path, table, "array now allowed");
1094 static int sysctl_check_table(const char *path, struct ctl_table *table)
1097 for (; table->procname; table++) {
1099 err |= sysctl_err(path, table, "Not a file");
1101 if ((table->proc_handler == proc_dostring) ||
1102 (table->proc_handler == proc_dointvec) ||
1103 (table->proc_handler == proc_douintvec) ||
1104 (table->proc_handler == proc_douintvec_minmax) ||
1105 (table->proc_handler == proc_dointvec_minmax) ||
1106 (table->proc_handler == proc_dointvec_jiffies) ||
1107 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1108 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1109 (table->proc_handler == proc_doulongvec_minmax) ||
1110 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1112 err |= sysctl_err(path, table, "No data");
1114 err |= sysctl_err(path, table, "No maxlen");
1116 err |= sysctl_check_table_array(path, table);
1118 if (!table->proc_handler)
1119 err |= sysctl_err(path, table, "No proc_handler");
1121 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1122 err |= sysctl_err(path, table, "bogus .mode 0%o",
1128 static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1129 struct ctl_table_root *link_root)
1131 struct ctl_table *link_table, *entry, *link;
1132 struct ctl_table_header *links;
1133 struct ctl_node *node;
1135 int nr_entries, name_bytes;
1139 for (entry = table; entry->procname; entry++) {
1141 name_bytes += strlen(entry->procname) + 1;
1144 links = kzalloc(sizeof(struct ctl_table_header) +
1145 sizeof(struct ctl_node)*nr_entries +
1146 sizeof(struct ctl_table)*(nr_entries + 1) +
1153 node = (struct ctl_node *)(links + 1);
1154 link_table = (struct ctl_table *)(node + nr_entries);
1155 link_name = (char *)&link_table[nr_entries + 1];
1157 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1158 int len = strlen(entry->procname) + 1;
1159 memcpy(link_name, entry->procname, len);
1160 link->procname = link_name;
1161 link->mode = S_IFLNK|S_IRWXUGO;
1162 link->data = link_root;
1165 init_header(links, dir->header.root, dir->header.set, node, link_table);
1166 links->nreg = nr_entries;
1171 static bool get_links(struct ctl_dir *dir,
1172 struct ctl_table *table, struct ctl_table_root *link_root)
1174 struct ctl_table_header *head;
1175 struct ctl_table *entry, *link;
1177 /* Are there links available for every entry in table? */
1178 for (entry = table; entry->procname; entry++) {
1179 const char *procname = entry->procname;
1180 link = find_entry(&head, dir, procname, strlen(procname));
1183 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1185 if (S_ISLNK(link->mode) && (link->data == link_root))
1190 /* The checks passed. Increase the registration count on the links */
1191 for (entry = table; entry->procname; entry++) {
1192 const char *procname = entry->procname;
1193 link = find_entry(&head, dir, procname, strlen(procname));
1199 static int insert_links(struct ctl_table_header *head)
1201 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1202 struct ctl_dir *core_parent = NULL;
1203 struct ctl_table_header *links;
1206 if (head->set == root_set)
1209 core_parent = xlate_dir(root_set, head->parent);
1210 if (IS_ERR(core_parent))
1213 if (get_links(core_parent, head->ctl_table, head->root))
1216 core_parent->header.nreg++;
1217 spin_unlock(&sysctl_lock);
1219 links = new_links(core_parent, head->ctl_table, head->root);
1221 spin_lock(&sysctl_lock);
1227 if (get_links(core_parent, head->ctl_table, head->root)) {
1232 err = insert_header(core_parent, links);
1236 drop_sysctl_table(&core_parent->header);
1241 * __register_sysctl_table - register a leaf sysctl table
1242 * @set: Sysctl tree to register on
1243 * @path: The path to the directory the sysctl table is in.
1244 * @table: the top-level table structure
1246 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1247 * array. A completely 0 filled entry terminates the table.
1249 * The members of the &struct ctl_table structure are used as follows:
1251 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1252 * enter a sysctl file
1254 * data - a pointer to data for use by proc_handler
1256 * maxlen - the maximum size in bytes of the data
1258 * mode - the file permissions for the /proc/sys file
1260 * child - must be %NULL.
1262 * proc_handler - the text handler routine (described below)
1264 * extra1, extra2 - extra pointers usable by the proc handler routines
1266 * Leaf nodes in the sysctl tree will be represented by a single file
1267 * under /proc; non-leaf nodes will be represented by directories.
1269 * There must be a proc_handler routine for any terminal nodes.
1270 * Several default handlers are available to cover common cases -
1272 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1273 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1274 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1276 * It is the handler's job to read the input buffer from user memory
1277 * and process it. The handler should return 0 on success.
1279 * This routine returns %NULL on a failure to register, and a pointer
1280 * to the table header on success.
1282 struct ctl_table_header *__register_sysctl_table(
1283 struct ctl_table_set *set,
1284 const char *path, struct ctl_table *table)
1286 struct ctl_table_root *root = set->dir.header.root;
1287 struct ctl_table_header *header;
1288 const char *name, *nextname;
1289 struct ctl_dir *dir;
1290 struct ctl_table *entry;
1291 struct ctl_node *node;
1294 for (entry = table; entry->procname; entry++)
1297 header = kzalloc(sizeof(struct ctl_table_header) +
1298 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1302 node = (struct ctl_node *)(header + 1);
1303 init_header(header, root, set, node, table);
1304 if (sysctl_check_table(path, table))
1307 spin_lock(&sysctl_lock);
1309 /* Reference moved down the diretory tree get_subdir */
1311 spin_unlock(&sysctl_lock);
1313 /* Find the directory for the ctl_table */
1314 for (name = path; name; name = nextname) {
1316 nextname = strchr(name, '/');
1318 namelen = nextname - name;
1321 namelen = strlen(name);
1326 dir = get_subdir(dir, name, namelen);
1331 spin_lock(&sysctl_lock);
1332 if (insert_header(dir, header))
1333 goto fail_put_dir_locked;
1335 drop_sysctl_table(&dir->header);
1336 spin_unlock(&sysctl_lock);
1340 fail_put_dir_locked:
1341 drop_sysctl_table(&dir->header);
1342 spin_unlock(&sysctl_lock);
1350 * register_sysctl - register a sysctl table
1351 * @path: The path to the directory the sysctl table is in.
1352 * @table: the table structure
1354 * Register a sysctl table. @table should be a filled in ctl_table
1355 * array. A completely 0 filled entry terminates the table.
1357 * See __register_sysctl_table for more details.
1359 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1361 return __register_sysctl_table(&sysctl_table_root.default_set,
1364 EXPORT_SYMBOL(register_sysctl);
1366 static char *append_path(const char *path, char *pos, const char *name)
1369 namelen = strlen(name);
1370 if (((pos - path) + namelen + 2) >= PATH_MAX)
1372 memcpy(pos, name, namelen);
1374 pos[namelen + 1] = '\0';
1379 static int count_subheaders(struct ctl_table *table)
1382 int nr_subheaders = 0;
1383 struct ctl_table *entry;
1385 /* special case: no directory and empty directory */
1386 if (!table || !table->procname)
1389 for (entry = table; entry->procname; entry++) {
1391 nr_subheaders += count_subheaders(entry->child);
1395 return nr_subheaders + has_files;
1398 static int register_leaf_sysctl_tables(const char *path, char *pos,
1399 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1400 struct ctl_table *table)
1402 struct ctl_table *ctl_table_arg = NULL;
1403 struct ctl_table *entry, *files;
1408 for (entry = table; entry->procname; entry++) {
1416 /* If there are mixed files and directories we need a new table */
1417 if (nr_dirs && nr_files) {
1418 struct ctl_table *new;
1419 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1424 ctl_table_arg = files;
1425 for (new = files, entry = table; entry->procname; entry++) {
1433 /* Register everything except a directory full of subdirectories */
1434 if (nr_files || !nr_dirs) {
1435 struct ctl_table_header *header;
1436 header = __register_sysctl_table(set, path, files);
1438 kfree(ctl_table_arg);
1442 /* Remember if we need to free the file table */
1443 header->ctl_table_arg = ctl_table_arg;
1444 **subheader = header;
1448 /* Recurse into the subdirectories. */
1449 for (entry = table; entry->procname; entry++) {
1455 err = -ENAMETOOLONG;
1456 child_pos = append_path(path, pos, entry->procname);
1460 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1468 /* On failure our caller will unregister all registered subheaders */
1473 * __register_sysctl_paths - register a sysctl table hierarchy
1474 * @set: Sysctl tree to register on
1475 * @path: The path to the directory the sysctl table is in.
1476 * @table: the top-level table structure
1478 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1479 * array. A completely 0 filled entry terminates the table.
1481 * See __register_sysctl_table for more details.
1483 struct ctl_table_header *__register_sysctl_paths(
1484 struct ctl_table_set *set,
1485 const struct ctl_path *path, struct ctl_table *table)
1487 struct ctl_table *ctl_table_arg = table;
1488 int nr_subheaders = count_subheaders(table);
1489 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1490 const struct ctl_path *component;
1491 char *new_path, *pos;
1493 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1498 for (component = path; component->procname; component++) {
1499 pos = append_path(new_path, pos, component->procname);
1503 while (table->procname && table->child && !table[1].procname) {
1504 pos = append_path(new_path, pos, table->procname);
1507 table = table->child;
1509 if (nr_subheaders == 1) {
1510 header = __register_sysctl_table(set, new_path, table);
1512 header->ctl_table_arg = ctl_table_arg;
1514 header = kzalloc(sizeof(*header) +
1515 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1519 subheaders = (struct ctl_table_header **) (header + 1);
1520 subheader = subheaders;
1521 header->ctl_table_arg = ctl_table_arg;
1523 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1525 goto err_register_leaves;
1532 err_register_leaves:
1533 while (subheader > subheaders) {
1534 struct ctl_table_header *subh = *(--subheader);
1535 struct ctl_table *table = subh->ctl_table_arg;
1536 unregister_sysctl_table(subh);
1545 * register_sysctl_table_path - register a sysctl table hierarchy
1546 * @path: The path to the directory the sysctl table is in.
1547 * @table: the top-level table structure
1549 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1550 * array. A completely 0 filled entry terminates the table.
1552 * See __register_sysctl_paths for more details.
1554 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1555 struct ctl_table *table)
1557 return __register_sysctl_paths(&sysctl_table_root.default_set,
1560 EXPORT_SYMBOL(register_sysctl_paths);
1563 * register_sysctl_table - register a sysctl table hierarchy
1564 * @table: the top-level table structure
1566 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1567 * array. A completely 0 filled entry terminates the table.
1569 * See register_sysctl_paths for more details.
1571 struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1573 static const struct ctl_path null_path[] = { {} };
1575 return register_sysctl_paths(null_path, table);
1577 EXPORT_SYMBOL(register_sysctl_table);
1579 static void put_links(struct ctl_table_header *header)
1581 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1582 struct ctl_table_root *root = header->root;
1583 struct ctl_dir *parent = header->parent;
1584 struct ctl_dir *core_parent;
1585 struct ctl_table *entry;
1587 if (header->set == root_set)
1590 core_parent = xlate_dir(root_set, parent);
1591 if (IS_ERR(core_parent))
1594 for (entry = header->ctl_table; entry->procname; entry++) {
1595 struct ctl_table_header *link_head;
1596 struct ctl_table *link;
1597 const char *name = entry->procname;
1599 link = find_entry(&link_head, core_parent, name, strlen(name));
1601 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1602 (S_ISLNK(link->mode) && (link->data == root)))) {
1603 drop_sysctl_table(link_head);
1606 pr_err("sysctl link missing during unregister: ");
1607 sysctl_print_dir(parent);
1608 pr_cont("/%s\n", name);
1613 static void drop_sysctl_table(struct ctl_table_header *header)
1615 struct ctl_dir *parent = header->parent;
1621 start_unregistering(header);
1622 if (!--header->count)
1623 kfree_rcu(header, rcu);
1626 drop_sysctl_table(&parent->header);
1630 * unregister_sysctl_table - unregister a sysctl table hierarchy
1631 * @header: the header returned from register_sysctl_table
1633 * Unregisters the sysctl table and all children. proc entries may not
1634 * actually be removed until they are no longer used by anyone.
1636 void unregister_sysctl_table(struct ctl_table_header * header)
1644 nr_subheaders = count_subheaders(header->ctl_table_arg);
1645 if (unlikely(nr_subheaders > 1)) {
1646 struct ctl_table_header **subheaders;
1649 subheaders = (struct ctl_table_header **)(header + 1);
1650 for (i = nr_subheaders -1; i >= 0; i--) {
1651 struct ctl_table_header *subh = subheaders[i];
1652 struct ctl_table *table = subh->ctl_table_arg;
1653 unregister_sysctl_table(subh);
1660 spin_lock(&sysctl_lock);
1661 drop_sysctl_table(header);
1662 spin_unlock(&sysctl_lock);
1664 EXPORT_SYMBOL(unregister_sysctl_table);
1666 void setup_sysctl_set(struct ctl_table_set *set,
1667 struct ctl_table_root *root,
1668 int (*is_seen)(struct ctl_table_set *))
1670 memset(set, 0, sizeof(*set));
1671 set->is_seen = is_seen;
1672 init_header(&set->dir.header, root, set, NULL, root_table);
1675 void retire_sysctl_set(struct ctl_table_set *set)
1677 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1680 int __init proc_sys_init(void)
1682 struct proc_dir_entry *proc_sys_root;
1684 proc_sys_root = proc_mkdir("sys", NULL);
1685 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1686 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1687 proc_sys_root->nlink = 0;
1689 return sysctl_init();