4 #include <linux/init.h>
5 #include <linux/sysctl.h>
6 #include <linux/poll.h>
7 #include <linux/proc_fs.h>
8 #include <linux/printk.h>
9 #include <linux/security.h>
10 #include <linux/sched.h>
11 #include <linux/namei.h>
13 #include <linux/module.h>
16 static const struct dentry_operations proc_sys_dentry_operations;
17 static const struct file_operations proc_sys_file_operations;
18 static const struct inode_operations proc_sys_inode_operations;
19 static const struct file_operations proc_sys_dir_file_operations;
20 static const struct inode_operations proc_sys_dir_operations;
22 /* Support for permanently empty directories */
24 struct ctl_table sysctl_mount_point[] = {
28 static bool is_empty_dir(struct ctl_table_header *head)
30 return head->ctl_table[0].child == sysctl_mount_point;
33 static void set_empty_dir(struct ctl_dir *dir)
35 dir->header.ctl_table[0].child = sysctl_mount_point;
38 static void clear_empty_dir(struct ctl_dir *dir)
41 dir->header.ctl_table[0].child = NULL;
44 void proc_sys_poll_notify(struct ctl_table_poll *poll)
49 atomic_inc(&poll->event);
50 wake_up_interruptible(&poll->wait);
53 static struct ctl_table root_table[] = {
56 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
60 static struct ctl_table_root sysctl_table_root = {
61 .default_set.dir.header = {
64 .ctl_table = root_table }},
65 .ctl_table_arg = root_table,
66 .root = &sysctl_table_root,
67 .set = &sysctl_table_root.default_set,
71 static DEFINE_SPINLOCK(sysctl_lock);
73 static void drop_sysctl_table(struct ctl_table_header *header);
74 static int sysctl_follow_link(struct ctl_table_header **phead,
75 struct ctl_table **pentry);
76 static int insert_links(struct ctl_table_header *head);
77 static void put_links(struct ctl_table_header *header);
79 static void sysctl_print_dir(struct ctl_dir *dir)
81 if (dir->header.parent)
82 sysctl_print_dir(dir->header.parent);
83 pr_cont("%s/", dir->header.ctl_table[0].procname);
86 static int namecmp(const char *name1, int len1, const char *name2, int len2)
95 cmp = memcmp(name1, name2, minlen);
101 /* Called under sysctl_lock */
102 static struct ctl_table *find_entry(struct ctl_table_header **phead,
103 struct ctl_dir *dir, const char *name, int namelen)
105 struct ctl_table_header *head;
106 struct ctl_table *entry;
107 struct rb_node *node = dir->root.rb_node;
111 struct ctl_node *ctl_node;
112 const char *procname;
115 ctl_node = rb_entry(node, struct ctl_node, node);
116 head = ctl_node->header;
117 entry = &head->ctl_table[ctl_node - head->node];
118 procname = entry->procname;
120 cmp = namecmp(name, namelen, procname, strlen(procname));
122 node = node->rb_left;
124 node = node->rb_right;
133 static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
135 struct rb_node *node = &head->node[entry - head->ctl_table].node;
136 struct rb_node **p = &head->parent->root.rb_node;
137 struct rb_node *parent = NULL;
138 const char *name = entry->procname;
139 int namelen = strlen(name);
142 struct ctl_table_header *parent_head;
143 struct ctl_table *parent_entry;
144 struct ctl_node *parent_node;
145 const char *parent_name;
149 parent_node = rb_entry(parent, struct ctl_node, node);
150 parent_head = parent_node->header;
151 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
152 parent_name = parent_entry->procname;
154 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
160 pr_err("sysctl duplicate entry: ");
161 sysctl_print_dir(head->parent);
162 pr_cont("/%s\n", entry->procname);
167 rb_link_node(node, parent, p);
168 rb_insert_color(node, &head->parent->root);
172 static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
174 struct rb_node *node = &head->node[entry - head->ctl_table].node;
176 rb_erase(node, &head->parent->root);
179 static void init_header(struct ctl_table_header *head,
180 struct ctl_table_root *root, struct ctl_table_set *set,
181 struct ctl_node *node, struct ctl_table *table)
183 head->ctl_table = table;
184 head->ctl_table_arg = table;
188 head->unregistering = NULL;
193 INIT_LIST_HEAD(&head->inodes);
195 struct ctl_table *entry;
196 for (entry = table; entry->procname; entry++, node++)
201 static void erase_header(struct ctl_table_header *head)
203 struct ctl_table *entry;
204 for (entry = head->ctl_table; entry->procname; entry++)
205 erase_entry(head, entry);
208 static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
210 struct ctl_table *entry;
213 /* Is this a permanently empty directory? */
214 if (is_empty_dir(&dir->header))
217 /* Am I creating a permanently empty directory? */
218 if (header->ctl_table == sysctl_mount_point) {
219 if (!RB_EMPTY_ROOT(&dir->root))
225 header->parent = dir;
226 err = insert_links(header);
229 for (entry = header->ctl_table; entry->procname; entry++) {
230 err = insert_entry(header, entry);
236 erase_header(header);
239 if (header->ctl_table == sysctl_mount_point)
240 clear_empty_dir(dir);
241 header->parent = NULL;
242 drop_sysctl_table(&dir->header);
246 /* called under sysctl_lock */
247 static int use_table(struct ctl_table_header *p)
249 if (unlikely(p->unregistering))
255 /* called under sysctl_lock */
256 static void unuse_table(struct ctl_table_header *p)
259 if (unlikely(p->unregistering))
260 complete(p->unregistering);
263 /* called under sysctl_lock */
264 static void proc_sys_prune_dcache(struct ctl_table_header *head)
266 struct inode *inode, *prev = NULL;
267 struct proc_inode *ei;
270 list_for_each_entry_rcu(ei, &head->inodes, sysctl_inodes) {
271 inode = igrab(&ei->vfs_inode);
276 d_prune_aliases(inode);
284 /* called under sysctl_lock, will reacquire if has to wait */
285 static void start_unregistering(struct ctl_table_header *p)
288 * if p->used is 0, nobody will ever touch that entry again;
289 * we'll eliminate all paths to it before dropping sysctl_lock
291 if (unlikely(p->used)) {
292 struct completion wait;
293 init_completion(&wait);
294 p->unregistering = &wait;
295 spin_unlock(&sysctl_lock);
296 wait_for_completion(&wait);
298 /* anything non-NULL; we'll never dereference it */
299 p->unregistering = ERR_PTR(-EINVAL);
300 spin_unlock(&sysctl_lock);
303 * Prune dentries for unregistered sysctls: namespaced sysctls
304 * can have duplicate names and contaminate dcache very badly.
306 proc_sys_prune_dcache(p);
308 * do not remove from the list until nobody holds it; walking the
309 * list in do_sysctl() relies on that.
311 spin_lock(&sysctl_lock);
315 static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
318 spin_lock(&sysctl_lock);
319 if (!use_table(head))
320 head = ERR_PTR(-ENOENT);
321 spin_unlock(&sysctl_lock);
325 static void sysctl_head_finish(struct ctl_table_header *head)
329 spin_lock(&sysctl_lock);
331 spin_unlock(&sysctl_lock);
334 static struct ctl_table_set *
335 lookup_header_set(struct ctl_table_root *root)
337 struct ctl_table_set *set = &root->default_set;
339 set = root->lookup(root);
343 static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
345 const char *name, int namelen)
347 struct ctl_table_header *head;
348 struct ctl_table *entry;
350 spin_lock(&sysctl_lock);
351 entry = find_entry(&head, dir, name, namelen);
352 if (entry && use_table(head))
356 spin_unlock(&sysctl_lock);
360 static struct ctl_node *first_usable_entry(struct rb_node *node)
362 struct ctl_node *ctl_node;
364 for (;node; node = rb_next(node)) {
365 ctl_node = rb_entry(node, struct ctl_node, node);
366 if (use_table(ctl_node->header))
372 static void first_entry(struct ctl_dir *dir,
373 struct ctl_table_header **phead, struct ctl_table **pentry)
375 struct ctl_table_header *head = NULL;
376 struct ctl_table *entry = NULL;
377 struct ctl_node *ctl_node;
379 spin_lock(&sysctl_lock);
380 ctl_node = first_usable_entry(rb_first(&dir->root));
381 spin_unlock(&sysctl_lock);
383 head = ctl_node->header;
384 entry = &head->ctl_table[ctl_node - head->node];
390 static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
392 struct ctl_table_header *head = *phead;
393 struct ctl_table *entry = *pentry;
394 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
396 spin_lock(&sysctl_lock);
399 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
400 spin_unlock(&sysctl_lock);
403 head = ctl_node->header;
404 entry = &head->ctl_table[ctl_node - head->node];
410 void register_sysctl_root(struct ctl_table_root *root)
415 * sysctl_perm does NOT grant the superuser all rights automatically, because
416 * some sysctl variables are readonly even to root.
419 static int test_perm(int mode, int op)
421 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
423 else if (in_egroup_p(GLOBAL_ROOT_GID))
425 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
430 static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
432 struct ctl_table_root *root = head->root;
435 if (root->permissions)
436 mode = root->permissions(head, table);
440 return test_perm(mode, op);
443 static struct inode *proc_sys_make_inode(struct super_block *sb,
444 struct ctl_table_header *head, struct ctl_table *table)
446 struct ctl_table_root *root = head->root;
448 struct proc_inode *ei;
450 inode = new_inode(sb);
454 inode->i_ino = get_next_ino();
458 spin_lock(&sysctl_lock);
459 if (unlikely(head->unregistering)) {
460 spin_unlock(&sysctl_lock);
466 ei->sysctl_entry = table;
467 list_add_rcu(&ei->sysctl_inodes, &head->inodes);
469 spin_unlock(&sysctl_lock);
471 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
472 inode->i_mode = table->mode;
473 if (!S_ISDIR(table->mode)) {
474 inode->i_mode |= S_IFREG;
475 inode->i_op = &proc_sys_inode_operations;
476 inode->i_fop = &proc_sys_file_operations;
478 inode->i_mode |= S_IFDIR;
479 inode->i_op = &proc_sys_dir_operations;
480 inode->i_fop = &proc_sys_dir_file_operations;
481 if (is_empty_dir(head))
482 make_empty_dir_inode(inode);
485 if (root->set_ownership)
486 root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
492 void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
494 spin_lock(&sysctl_lock);
495 list_del_rcu(&PROC_I(inode)->sysctl_inodes);
497 kfree_rcu(head, rcu);
498 spin_unlock(&sysctl_lock);
501 static struct ctl_table_header *grab_header(struct inode *inode)
503 struct ctl_table_header *head = PROC_I(inode)->sysctl;
505 head = &sysctl_table_root.default_set.dir.header;
506 return sysctl_head_grab(head);
509 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
512 struct ctl_table_header *head = grab_header(dir);
513 struct ctl_table_header *h = NULL;
514 const struct qstr *name = &dentry->d_name;
517 struct dentry *err = ERR_PTR(-ENOENT);
518 struct ctl_dir *ctl_dir;
522 return ERR_CAST(head);
524 ctl_dir = container_of(head, struct ctl_dir, header);
526 p = lookup_entry(&h, ctl_dir, name->name, name->len);
530 if (S_ISLNK(p->mode)) {
531 ret = sysctl_follow_link(&h, &p);
537 err = ERR_PTR(-ENOMEM);
538 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
543 d_set_d_op(dentry, &proc_sys_dentry_operations);
544 d_add(dentry, inode);
548 sysctl_head_finish(h);
549 sysctl_head_finish(head);
553 static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
554 size_t count, loff_t *ppos, int write)
556 struct inode *inode = file_inode(filp);
557 struct ctl_table_header *head = grab_header(inode);
558 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
563 return PTR_ERR(head);
566 * At this point we know that the sysctl was not unregistered
567 * and won't be until we finish.
570 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
573 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
575 if (!table->proc_handler)
578 /* careful: calling conventions are nasty here */
580 error = table->proc_handler(table, write, buf, &res, ppos);
584 sysctl_head_finish(head);
589 static ssize_t proc_sys_read(struct file *filp, char __user *buf,
590 size_t count, loff_t *ppos)
592 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
595 static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
596 size_t count, loff_t *ppos)
598 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
601 static int proc_sys_open(struct inode *inode, struct file *filp)
603 struct ctl_table_header *head = grab_header(inode);
604 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
606 /* sysctl was unregistered */
608 return PTR_ERR(head);
611 filp->private_data = proc_sys_poll_event(table->poll);
613 sysctl_head_finish(head);
618 static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
620 struct inode *inode = file_inode(filp);
621 struct ctl_table_header *head = grab_header(inode);
622 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
623 unsigned int ret = DEFAULT_POLLMASK;
626 /* sysctl was unregistered */
628 return POLLERR | POLLHUP;
630 if (!table->proc_handler)
636 event = (unsigned long)filp->private_data;
637 poll_wait(filp, &table->poll->wait, wait);
639 if (event != atomic_read(&table->poll->event)) {
640 filp->private_data = proc_sys_poll_event(table->poll);
641 ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI;
645 sysctl_head_finish(head);
650 static bool proc_sys_fill_cache(struct file *file,
651 struct dir_context *ctx,
652 struct ctl_table_header *head,
653 struct ctl_table *table)
655 struct dentry *child, *dir = file->f_path.dentry;
659 unsigned type = DT_UNKNOWN;
661 qname.name = table->procname;
662 qname.len = strlen(table->procname);
663 qname.hash = full_name_hash(dir, qname.name, qname.len);
665 child = d_lookup(dir, &qname);
667 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
668 child = d_alloc_parallel(dir, &qname, &wq);
671 if (d_in_lookup(child)) {
672 inode = proc_sys_make_inode(dir->d_sb, head, table);
674 d_lookup_done(child);
678 d_set_d_op(child, &proc_sys_dentry_operations);
682 inode = d_inode(child);
684 type = inode->i_mode >> 12;
686 return dir_emit(ctx, qname.name, qname.len, ino, type);
689 static bool proc_sys_link_fill_cache(struct file *file,
690 struct dir_context *ctx,
691 struct ctl_table_header *head,
692 struct ctl_table *table)
695 head = sysctl_head_grab(head);
697 if (S_ISLNK(table->mode)) {
698 /* It is not an error if we can not follow the link ignore it */
699 int err = sysctl_follow_link(&head, &table);
704 ret = proc_sys_fill_cache(file, ctx, head, table);
706 sysctl_head_finish(head);
710 static int scan(struct ctl_table_header *head, struct ctl_table *table,
711 unsigned long *pos, struct file *file,
712 struct dir_context *ctx)
716 if ((*pos)++ < ctx->pos)
719 if (unlikely(S_ISLNK(table->mode)))
720 res = proc_sys_link_fill_cache(file, ctx, head, table);
722 res = proc_sys_fill_cache(file, ctx, head, table);
730 static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
732 struct ctl_table_header *head = grab_header(file_inode(file));
733 struct ctl_table_header *h = NULL;
734 struct ctl_table *entry;
735 struct ctl_dir *ctl_dir;
739 return PTR_ERR(head);
741 ctl_dir = container_of(head, struct ctl_dir, header);
743 if (!dir_emit_dots(file, ctx))
748 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
749 if (!scan(h, entry, &pos, file, ctx)) {
750 sysctl_head_finish(h);
755 sysctl_head_finish(head);
759 static int proc_sys_permission(struct inode *inode, int mask)
762 * sysctl entries that are not writeable,
763 * are _NOT_ writeable, capabilities or not.
765 struct ctl_table_header *head;
766 struct ctl_table *table;
769 /* Executable files are not allowed under /proc/sys/ */
770 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
773 head = grab_header(inode);
775 return PTR_ERR(head);
777 table = PROC_I(inode)->sysctl_entry;
778 if (!table) /* global root - r-xr-xr-x */
779 error = mask & MAY_WRITE ? -EACCES : 0;
780 else /* Use the permissions on the sysctl table entry */
781 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
783 sysctl_head_finish(head);
787 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
789 struct inode *inode = d_inode(dentry);
792 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
795 error = setattr_prepare(dentry, attr);
799 setattr_copy(inode, attr);
800 mark_inode_dirty(inode);
804 static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
806 struct inode *inode = d_inode(dentry);
807 struct ctl_table_header *head = grab_header(inode);
808 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
811 return PTR_ERR(head);
813 generic_fillattr(inode, stat);
815 stat->mode = (stat->mode & S_IFMT) | table->mode;
817 sysctl_head_finish(head);
821 static const struct file_operations proc_sys_file_operations = {
822 .open = proc_sys_open,
823 .poll = proc_sys_poll,
824 .read = proc_sys_read,
825 .write = proc_sys_write,
826 .llseek = default_llseek,
829 static const struct file_operations proc_sys_dir_file_operations = {
830 .read = generic_read_dir,
831 .iterate_shared = proc_sys_readdir,
832 .llseek = generic_file_llseek,
835 static const struct inode_operations proc_sys_inode_operations = {
836 .permission = proc_sys_permission,
837 .setattr = proc_sys_setattr,
838 .getattr = proc_sys_getattr,
841 static const struct inode_operations proc_sys_dir_operations = {
842 .lookup = proc_sys_lookup,
843 .permission = proc_sys_permission,
844 .setattr = proc_sys_setattr,
845 .getattr = proc_sys_getattr,
848 static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
850 if (flags & LOOKUP_RCU)
852 return !PROC_I(d_inode(dentry))->sysctl->unregistering;
855 static int proc_sys_delete(const struct dentry *dentry)
857 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
860 static int sysctl_is_seen(struct ctl_table_header *p)
862 struct ctl_table_set *set = p->set;
864 spin_lock(&sysctl_lock);
865 if (p->unregistering)
867 else if (!set->is_seen)
870 res = set->is_seen(set);
871 spin_unlock(&sysctl_lock);
875 static int proc_sys_compare(const struct dentry *dentry,
876 unsigned int len, const char *str, const struct qstr *name)
878 struct ctl_table_header *head;
881 /* Although proc doesn't have negative dentries, rcu-walk means
882 * that inode here can be NULL */
883 /* AV: can it, indeed? */
884 inode = d_inode_rcu(dentry);
887 if (name->len != len)
889 if (memcmp(name->name, str, len))
891 head = rcu_dereference(PROC_I(inode)->sysctl);
892 return !head || !sysctl_is_seen(head);
895 static const struct dentry_operations proc_sys_dentry_operations = {
896 .d_revalidate = proc_sys_revalidate,
897 .d_delete = proc_sys_delete,
898 .d_compare = proc_sys_compare,
901 static struct ctl_dir *find_subdir(struct ctl_dir *dir,
902 const char *name, int namelen)
904 struct ctl_table_header *head;
905 struct ctl_table *entry;
907 entry = find_entry(&head, dir, name, namelen);
909 return ERR_PTR(-ENOENT);
910 if (!S_ISDIR(entry->mode))
911 return ERR_PTR(-ENOTDIR);
912 return container_of(head, struct ctl_dir, header);
915 static struct ctl_dir *new_dir(struct ctl_table_set *set,
916 const char *name, int namelen)
918 struct ctl_table *table;
920 struct ctl_node *node;
923 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
924 sizeof(struct ctl_table)*2 + namelen + 1,
929 node = (struct ctl_node *)(new + 1);
930 table = (struct ctl_table *)(node + 1);
931 new_name = (char *)(table + 2);
932 memcpy(new_name, name, namelen);
933 new_name[namelen] = '\0';
934 table[0].procname = new_name;
935 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
936 init_header(&new->header, set->dir.header.root, set, node, table);
942 * get_subdir - find or create a subdir with the specified name.
943 * @dir: Directory to create the subdirectory in
944 * @name: The name of the subdirectory to find or create
945 * @namelen: The length of name
947 * Takes a directory with an elevated reference count so we know that
948 * if we drop the lock the directory will not go away. Upon success
949 * the reference is moved from @dir to the returned subdirectory.
950 * Upon error an error code is returned and the reference on @dir is
953 static struct ctl_dir *get_subdir(struct ctl_dir *dir,
954 const char *name, int namelen)
956 struct ctl_table_set *set = dir->header.set;
957 struct ctl_dir *subdir, *new = NULL;
960 spin_lock(&sysctl_lock);
961 subdir = find_subdir(dir, name, namelen);
964 if (PTR_ERR(subdir) != -ENOENT)
967 spin_unlock(&sysctl_lock);
968 new = new_dir(set, name, namelen);
969 spin_lock(&sysctl_lock);
970 subdir = ERR_PTR(-ENOMEM);
974 /* Was the subdir added while we dropped the lock? */
975 subdir = find_subdir(dir, name, namelen);
978 if (PTR_ERR(subdir) != -ENOENT)
981 /* Nope. Use the our freshly made directory entry. */
982 err = insert_header(dir, &new->header);
983 subdir = ERR_PTR(err);
988 subdir->header.nreg++;
990 if (IS_ERR(subdir)) {
991 pr_err("sysctl could not get directory: ");
992 sysctl_print_dir(dir);
993 pr_cont("/%*.*s %ld\n",
994 namelen, namelen, name, PTR_ERR(subdir));
996 drop_sysctl_table(&dir->header);
998 drop_sysctl_table(&new->header);
999 spin_unlock(&sysctl_lock);
1003 static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
1005 struct ctl_dir *parent;
1006 const char *procname;
1007 if (!dir->header.parent)
1009 parent = xlate_dir(set, dir->header.parent);
1012 procname = dir->header.ctl_table[0].procname;
1013 return find_subdir(parent, procname, strlen(procname));
1016 static int sysctl_follow_link(struct ctl_table_header **phead,
1017 struct ctl_table **pentry)
1019 struct ctl_table_header *head;
1020 struct ctl_table_root *root;
1021 struct ctl_table_set *set;
1022 struct ctl_table *entry;
1023 struct ctl_dir *dir;
1027 spin_lock(&sysctl_lock);
1028 root = (*pentry)->data;
1029 set = lookup_header_set(root);
1030 dir = xlate_dir(set, (*phead)->parent);
1034 const char *procname = (*pentry)->procname;
1036 entry = find_entry(&head, dir, procname, strlen(procname));
1038 if (entry && use_table(head)) {
1039 unuse_table(*phead);
1046 spin_unlock(&sysctl_lock);
1050 static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
1052 struct va_format vaf;
1055 va_start(args, fmt);
1059 pr_err("sysctl table check failed: %s/%s %pV\n",
1060 path, table->procname, &vaf);
1066 static int sysctl_check_table(const char *path, struct ctl_table *table)
1069 for (; table->procname; table++) {
1071 err = sysctl_err(path, table, "Not a file");
1073 if ((table->proc_handler == proc_dostring) ||
1074 (table->proc_handler == proc_dointvec) ||
1075 (table->proc_handler == proc_dointvec_minmax) ||
1076 (table->proc_handler == proc_dointvec_jiffies) ||
1077 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1078 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1079 (table->proc_handler == proc_doulongvec_minmax) ||
1080 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1082 err = sysctl_err(path, table, "No data");
1084 err = sysctl_err(path, table, "No maxlen");
1086 if (!table->proc_handler)
1087 err = sysctl_err(path, table, "No proc_handler");
1089 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1090 err = sysctl_err(path, table, "bogus .mode 0%o",
1096 static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1097 struct ctl_table_root *link_root)
1099 struct ctl_table *link_table, *entry, *link;
1100 struct ctl_table_header *links;
1101 struct ctl_node *node;
1103 int nr_entries, name_bytes;
1107 for (entry = table; entry->procname; entry++) {
1109 name_bytes += strlen(entry->procname) + 1;
1112 links = kzalloc(sizeof(struct ctl_table_header) +
1113 sizeof(struct ctl_node)*nr_entries +
1114 sizeof(struct ctl_table)*(nr_entries + 1) +
1121 node = (struct ctl_node *)(links + 1);
1122 link_table = (struct ctl_table *)(node + nr_entries);
1123 link_name = (char *)&link_table[nr_entries + 1];
1125 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1126 int len = strlen(entry->procname) + 1;
1127 memcpy(link_name, entry->procname, len);
1128 link->procname = link_name;
1129 link->mode = S_IFLNK|S_IRWXUGO;
1130 link->data = link_root;
1133 init_header(links, dir->header.root, dir->header.set, node, link_table);
1134 links->nreg = nr_entries;
1139 static bool get_links(struct ctl_dir *dir,
1140 struct ctl_table *table, struct ctl_table_root *link_root)
1142 struct ctl_table_header *head;
1143 struct ctl_table *entry, *link;
1145 /* Are there links available for every entry in table? */
1146 for (entry = table; entry->procname; entry++) {
1147 const char *procname = entry->procname;
1148 link = find_entry(&head, dir, procname, strlen(procname));
1151 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1153 if (S_ISLNK(link->mode) && (link->data == link_root))
1158 /* The checks passed. Increase the registration count on the links */
1159 for (entry = table; entry->procname; entry++) {
1160 const char *procname = entry->procname;
1161 link = find_entry(&head, dir, procname, strlen(procname));
1167 static int insert_links(struct ctl_table_header *head)
1169 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1170 struct ctl_dir *core_parent = NULL;
1171 struct ctl_table_header *links;
1174 if (head->set == root_set)
1177 core_parent = xlate_dir(root_set, head->parent);
1178 if (IS_ERR(core_parent))
1181 if (get_links(core_parent, head->ctl_table, head->root))
1184 core_parent->header.nreg++;
1185 spin_unlock(&sysctl_lock);
1187 links = new_links(core_parent, head->ctl_table, head->root);
1189 spin_lock(&sysctl_lock);
1195 if (get_links(core_parent, head->ctl_table, head->root)) {
1200 err = insert_header(core_parent, links);
1204 drop_sysctl_table(&core_parent->header);
1209 * __register_sysctl_table - register a leaf sysctl table
1210 * @set: Sysctl tree to register on
1211 * @path: The path to the directory the sysctl table is in.
1212 * @table: the top-level table structure
1214 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1215 * array. A completely 0 filled entry terminates the table.
1217 * The members of the &struct ctl_table structure are used as follows:
1219 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1220 * enter a sysctl file
1222 * data - a pointer to data for use by proc_handler
1224 * maxlen - the maximum size in bytes of the data
1226 * mode - the file permissions for the /proc/sys file
1228 * child - must be %NULL.
1230 * proc_handler - the text handler routine (described below)
1232 * extra1, extra2 - extra pointers usable by the proc handler routines
1234 * Leaf nodes in the sysctl tree will be represented by a single file
1235 * under /proc; non-leaf nodes will be represented by directories.
1237 * There must be a proc_handler routine for any terminal nodes.
1238 * Several default handlers are available to cover common cases -
1240 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1241 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1242 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1244 * It is the handler's job to read the input buffer from user memory
1245 * and process it. The handler should return 0 on success.
1247 * This routine returns %NULL on a failure to register, and a pointer
1248 * to the table header on success.
1250 struct ctl_table_header *__register_sysctl_table(
1251 struct ctl_table_set *set,
1252 const char *path, struct ctl_table *table)
1254 struct ctl_table_root *root = set->dir.header.root;
1255 struct ctl_table_header *header;
1256 const char *name, *nextname;
1257 struct ctl_dir *dir;
1258 struct ctl_table *entry;
1259 struct ctl_node *node;
1262 for (entry = table; entry->procname; entry++)
1265 header = kzalloc(sizeof(struct ctl_table_header) +
1266 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1270 node = (struct ctl_node *)(header + 1);
1271 init_header(header, root, set, node, table);
1272 if (sysctl_check_table(path, table))
1275 spin_lock(&sysctl_lock);
1277 /* Reference moved down the diretory tree get_subdir */
1279 spin_unlock(&sysctl_lock);
1281 /* Find the directory for the ctl_table */
1282 for (name = path; name; name = nextname) {
1284 nextname = strchr(name, '/');
1286 namelen = nextname - name;
1289 namelen = strlen(name);
1294 dir = get_subdir(dir, name, namelen);
1299 spin_lock(&sysctl_lock);
1300 if (insert_header(dir, header))
1301 goto fail_put_dir_locked;
1303 drop_sysctl_table(&dir->header);
1304 spin_unlock(&sysctl_lock);
1308 fail_put_dir_locked:
1309 drop_sysctl_table(&dir->header);
1310 spin_unlock(&sysctl_lock);
1318 * register_sysctl - register a sysctl table
1319 * @path: The path to the directory the sysctl table is in.
1320 * @table: the table structure
1322 * Register a sysctl table. @table should be a filled in ctl_table
1323 * array. A completely 0 filled entry terminates the table.
1325 * See __register_sysctl_table for more details.
1327 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1329 return __register_sysctl_table(&sysctl_table_root.default_set,
1332 EXPORT_SYMBOL(register_sysctl);
1334 static char *append_path(const char *path, char *pos, const char *name)
1337 namelen = strlen(name);
1338 if (((pos - path) + namelen + 2) >= PATH_MAX)
1340 memcpy(pos, name, namelen);
1342 pos[namelen + 1] = '\0';
1347 static int count_subheaders(struct ctl_table *table)
1350 int nr_subheaders = 0;
1351 struct ctl_table *entry;
1353 /* special case: no directory and empty directory */
1354 if (!table || !table->procname)
1357 for (entry = table; entry->procname; entry++) {
1359 nr_subheaders += count_subheaders(entry->child);
1363 return nr_subheaders + has_files;
1366 static int register_leaf_sysctl_tables(const char *path, char *pos,
1367 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1368 struct ctl_table *table)
1370 struct ctl_table *ctl_table_arg = NULL;
1371 struct ctl_table *entry, *files;
1376 for (entry = table; entry->procname; entry++) {
1384 /* If there are mixed files and directories we need a new table */
1385 if (nr_dirs && nr_files) {
1386 struct ctl_table *new;
1387 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1392 ctl_table_arg = files;
1393 for (new = files, entry = table; entry->procname; entry++) {
1401 /* Register everything except a directory full of subdirectories */
1402 if (nr_files || !nr_dirs) {
1403 struct ctl_table_header *header;
1404 header = __register_sysctl_table(set, path, files);
1406 kfree(ctl_table_arg);
1410 /* Remember if we need to free the file table */
1411 header->ctl_table_arg = ctl_table_arg;
1412 **subheader = header;
1416 /* Recurse into the subdirectories. */
1417 for (entry = table; entry->procname; entry++) {
1423 err = -ENAMETOOLONG;
1424 child_pos = append_path(path, pos, entry->procname);
1428 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1436 /* On failure our caller will unregister all registered subheaders */
1441 * __register_sysctl_paths - register a sysctl table hierarchy
1442 * @set: Sysctl tree to register on
1443 * @path: The path to the directory the sysctl table is in.
1444 * @table: the top-level table structure
1446 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1447 * array. A completely 0 filled entry terminates the table.
1449 * See __register_sysctl_table for more details.
1451 struct ctl_table_header *__register_sysctl_paths(
1452 struct ctl_table_set *set,
1453 const struct ctl_path *path, struct ctl_table *table)
1455 struct ctl_table *ctl_table_arg = table;
1456 int nr_subheaders = count_subheaders(table);
1457 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1458 const struct ctl_path *component;
1459 char *new_path, *pos;
1461 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1466 for (component = path; component->procname; component++) {
1467 pos = append_path(new_path, pos, component->procname);
1471 while (table->procname && table->child && !table[1].procname) {
1472 pos = append_path(new_path, pos, table->procname);
1475 table = table->child;
1477 if (nr_subheaders == 1) {
1478 header = __register_sysctl_table(set, new_path, table);
1480 header->ctl_table_arg = ctl_table_arg;
1482 header = kzalloc(sizeof(*header) +
1483 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1487 subheaders = (struct ctl_table_header **) (header + 1);
1488 subheader = subheaders;
1489 header->ctl_table_arg = ctl_table_arg;
1491 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1493 goto err_register_leaves;
1500 err_register_leaves:
1501 while (subheader > subheaders) {
1502 struct ctl_table_header *subh = *(--subheader);
1503 struct ctl_table *table = subh->ctl_table_arg;
1504 unregister_sysctl_table(subh);
1513 * register_sysctl_table_path - register a sysctl table hierarchy
1514 * @path: The path to the directory the sysctl table is in.
1515 * @table: the top-level table structure
1517 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1518 * array. A completely 0 filled entry terminates the table.
1520 * See __register_sysctl_paths for more details.
1522 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1523 struct ctl_table *table)
1525 return __register_sysctl_paths(&sysctl_table_root.default_set,
1528 EXPORT_SYMBOL(register_sysctl_paths);
1531 * register_sysctl_table - register a sysctl table hierarchy
1532 * @table: the top-level table structure
1534 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1535 * array. A completely 0 filled entry terminates the table.
1537 * See register_sysctl_paths for more details.
1539 struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1541 static const struct ctl_path null_path[] = { {} };
1543 return register_sysctl_paths(null_path, table);
1545 EXPORT_SYMBOL(register_sysctl_table);
1547 static void put_links(struct ctl_table_header *header)
1549 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1550 struct ctl_table_root *root = header->root;
1551 struct ctl_dir *parent = header->parent;
1552 struct ctl_dir *core_parent;
1553 struct ctl_table *entry;
1555 if (header->set == root_set)
1558 core_parent = xlate_dir(root_set, parent);
1559 if (IS_ERR(core_parent))
1562 for (entry = header->ctl_table; entry->procname; entry++) {
1563 struct ctl_table_header *link_head;
1564 struct ctl_table *link;
1565 const char *name = entry->procname;
1567 link = find_entry(&link_head, core_parent, name, strlen(name));
1569 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1570 (S_ISLNK(link->mode) && (link->data == root)))) {
1571 drop_sysctl_table(link_head);
1574 pr_err("sysctl link missing during unregister: ");
1575 sysctl_print_dir(parent);
1576 pr_cont("/%s\n", name);
1581 static void drop_sysctl_table(struct ctl_table_header *header)
1583 struct ctl_dir *parent = header->parent;
1589 start_unregistering(header);
1590 if (!--header->count)
1591 kfree_rcu(header, rcu);
1594 drop_sysctl_table(&parent->header);
1598 * unregister_sysctl_table - unregister a sysctl table hierarchy
1599 * @header: the header returned from register_sysctl_table
1601 * Unregisters the sysctl table and all children. proc entries may not
1602 * actually be removed until they are no longer used by anyone.
1604 void unregister_sysctl_table(struct ctl_table_header * header)
1612 nr_subheaders = count_subheaders(header->ctl_table_arg);
1613 if (unlikely(nr_subheaders > 1)) {
1614 struct ctl_table_header **subheaders;
1617 subheaders = (struct ctl_table_header **)(header + 1);
1618 for (i = nr_subheaders -1; i >= 0; i--) {
1619 struct ctl_table_header *subh = subheaders[i];
1620 struct ctl_table *table = subh->ctl_table_arg;
1621 unregister_sysctl_table(subh);
1628 spin_lock(&sysctl_lock);
1629 drop_sysctl_table(header);
1630 spin_unlock(&sysctl_lock);
1632 EXPORT_SYMBOL(unregister_sysctl_table);
1634 void setup_sysctl_set(struct ctl_table_set *set,
1635 struct ctl_table_root *root,
1636 int (*is_seen)(struct ctl_table_set *))
1638 memset(set, 0, sizeof(*set));
1639 set->is_seen = is_seen;
1640 init_header(&set->dir.header, root, set, NULL, root_table);
1643 void retire_sysctl_set(struct ctl_table_set *set)
1645 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1648 int __init proc_sys_init(void)
1650 struct proc_dir_entry *proc_sys_root;
1652 proc_sys_root = proc_mkdir("sys", NULL);
1653 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1654 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1655 proc_sys_root->nlink = 0;
1657 return sysctl_init();