1 // SPDX-License-Identifier: GPL-2.0
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>
15 #include <linux/module.h>
16 #include <linux/kmemleak.h>
19 static const struct dentry_operations proc_sys_dentry_operations;
20 static const struct file_operations proc_sys_file_operations;
21 static const struct inode_operations proc_sys_inode_operations;
22 static const struct file_operations proc_sys_dir_file_operations;
23 static const struct inode_operations proc_sys_dir_operations;
25 /* Support for permanently empty directories */
27 struct ctl_table sysctl_mount_point[] = {
31 static bool is_empty_dir(struct ctl_table_header *head)
33 return head->ctl_table[0].child == sysctl_mount_point;
36 static void set_empty_dir(struct ctl_dir *dir)
38 dir->header.ctl_table[0].child = sysctl_mount_point;
41 static void clear_empty_dir(struct ctl_dir *dir)
44 dir->header.ctl_table[0].child = NULL;
47 void proc_sys_poll_notify(struct ctl_table_poll *poll)
52 atomic_inc(&poll->event);
53 wake_up_interruptible(&poll->wait);
56 static struct ctl_table root_table[] = {
59 .mode = S_IFDIR|S_IRUGO|S_IXUGO,
63 static struct ctl_table_root sysctl_table_root = {
64 .default_set.dir.header = {
67 .ctl_table = root_table }},
68 .ctl_table_arg = root_table,
69 .root = &sysctl_table_root,
70 .set = &sysctl_table_root.default_set,
74 static DEFINE_SPINLOCK(sysctl_lock);
76 static void drop_sysctl_table(struct ctl_table_header *header);
77 static int sysctl_follow_link(struct ctl_table_header **phead,
78 struct ctl_table **pentry);
79 static int insert_links(struct ctl_table_header *head);
80 static void put_links(struct ctl_table_header *header);
82 static void sysctl_print_dir(struct ctl_dir *dir)
84 if (dir->header.parent)
85 sysctl_print_dir(dir->header.parent);
86 pr_cont("%s/", dir->header.ctl_table[0].procname);
89 static int namecmp(const char *name1, int len1, const char *name2, int len2)
98 cmp = memcmp(name1, name2, minlen);
104 /* Called under sysctl_lock */
105 static struct ctl_table *find_entry(struct ctl_table_header **phead,
106 struct ctl_dir *dir, const char *name, int namelen)
108 struct ctl_table_header *head;
109 struct ctl_table *entry;
110 struct rb_node *node = dir->root.rb_node;
114 struct ctl_node *ctl_node;
115 const char *procname;
118 ctl_node = rb_entry(node, struct ctl_node, node);
119 head = ctl_node->header;
120 entry = &head->ctl_table[ctl_node - head->node];
121 procname = entry->procname;
123 cmp = namecmp(name, namelen, procname, strlen(procname));
125 node = node->rb_left;
127 node = node->rb_right;
136 static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
138 struct rb_node *node = &head->node[entry - head->ctl_table].node;
139 struct rb_node **p = &head->parent->root.rb_node;
140 struct rb_node *parent = NULL;
141 const char *name = entry->procname;
142 int namelen = strlen(name);
145 struct ctl_table_header *parent_head;
146 struct ctl_table *parent_entry;
147 struct ctl_node *parent_node;
148 const char *parent_name;
152 parent_node = rb_entry(parent, struct ctl_node, node);
153 parent_head = parent_node->header;
154 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
155 parent_name = parent_entry->procname;
157 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
163 pr_err("sysctl duplicate entry: ");
164 sysctl_print_dir(head->parent);
165 pr_cont("/%s\n", entry->procname);
170 rb_link_node(node, parent, p);
171 rb_insert_color(node, &head->parent->root);
175 static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
177 struct rb_node *node = &head->node[entry - head->ctl_table].node;
179 rb_erase(node, &head->parent->root);
182 static void init_header(struct ctl_table_header *head,
183 struct ctl_table_root *root, struct ctl_table_set *set,
184 struct ctl_node *node, struct ctl_table *table)
186 head->ctl_table = table;
187 head->ctl_table_arg = table;
191 head->unregistering = NULL;
196 INIT_HLIST_HEAD(&head->inodes);
198 struct ctl_table *entry;
199 for (entry = table; entry->procname; entry++, node++)
204 static void erase_header(struct ctl_table_header *head)
206 struct ctl_table *entry;
207 for (entry = head->ctl_table; entry->procname; entry++)
208 erase_entry(head, entry);
211 static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
213 struct ctl_table *entry;
216 /* Is this a permanently empty directory? */
217 if (is_empty_dir(&dir->header))
220 /* Am I creating a permanently empty directory? */
221 if (header->ctl_table == sysctl_mount_point) {
222 if (!RB_EMPTY_ROOT(&dir->root))
228 header->parent = dir;
229 err = insert_links(header);
232 for (entry = header->ctl_table; entry->procname; entry++) {
233 err = insert_entry(header, entry);
239 erase_header(header);
242 if (header->ctl_table == sysctl_mount_point)
243 clear_empty_dir(dir);
244 header->parent = NULL;
245 drop_sysctl_table(&dir->header);
249 /* called under sysctl_lock */
250 static int use_table(struct ctl_table_header *p)
252 if (unlikely(p->unregistering))
258 /* called under sysctl_lock */
259 static void unuse_table(struct ctl_table_header *p)
262 if (unlikely(p->unregistering))
263 complete(p->unregistering);
266 static void proc_sys_prune_dcache(struct ctl_table_header *head)
269 struct proc_inode *ei;
270 struct hlist_node *node;
271 struct super_block *sb;
275 node = hlist_first_rcu(&head->inodes);
278 ei = hlist_entry(node, struct proc_inode, sysctl_inodes);
279 spin_lock(&sysctl_lock);
280 hlist_del_init_rcu(&ei->sysctl_inodes);
281 spin_unlock(&sysctl_lock);
283 inode = &ei->vfs_inode;
285 if (!atomic_inc_not_zero(&sb->s_active))
287 inode = igrab(inode);
289 if (unlikely(!inode)) {
290 deactivate_super(sb);
295 d_prune_aliases(inode);
297 deactivate_super(sb);
304 /* called under sysctl_lock, will reacquire if has to wait */
305 static void start_unregistering(struct ctl_table_header *p)
308 * if p->used is 0, nobody will ever touch that entry again;
309 * we'll eliminate all paths to it before dropping sysctl_lock
311 if (unlikely(p->used)) {
312 struct completion wait;
313 init_completion(&wait);
314 p->unregistering = &wait;
315 spin_unlock(&sysctl_lock);
316 wait_for_completion(&wait);
318 /* anything non-NULL; we'll never dereference it */
319 p->unregistering = ERR_PTR(-EINVAL);
320 spin_unlock(&sysctl_lock);
323 * Prune dentries for unregistered sysctls: namespaced sysctls
324 * can have duplicate names and contaminate dcache very badly.
326 proc_sys_prune_dcache(p);
328 * do not remove from the list until nobody holds it; walking the
329 * list in do_sysctl() relies on that.
331 spin_lock(&sysctl_lock);
335 static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
338 spin_lock(&sysctl_lock);
339 if (!use_table(head))
340 head = ERR_PTR(-ENOENT);
341 spin_unlock(&sysctl_lock);
345 static void sysctl_head_finish(struct ctl_table_header *head)
349 spin_lock(&sysctl_lock);
351 spin_unlock(&sysctl_lock);
354 static struct ctl_table_set *
355 lookup_header_set(struct ctl_table_root *root)
357 struct ctl_table_set *set = &root->default_set;
359 set = root->lookup(root);
363 static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
365 const char *name, int namelen)
367 struct ctl_table_header *head;
368 struct ctl_table *entry;
370 spin_lock(&sysctl_lock);
371 entry = find_entry(&head, dir, name, namelen);
372 if (entry && use_table(head))
376 spin_unlock(&sysctl_lock);
380 static struct ctl_node *first_usable_entry(struct rb_node *node)
382 struct ctl_node *ctl_node;
384 for (;node; node = rb_next(node)) {
385 ctl_node = rb_entry(node, struct ctl_node, node);
386 if (use_table(ctl_node->header))
392 static void first_entry(struct ctl_dir *dir,
393 struct ctl_table_header **phead, struct ctl_table **pentry)
395 struct ctl_table_header *head = NULL;
396 struct ctl_table *entry = NULL;
397 struct ctl_node *ctl_node;
399 spin_lock(&sysctl_lock);
400 ctl_node = first_usable_entry(rb_first(&dir->root));
401 spin_unlock(&sysctl_lock);
403 head = ctl_node->header;
404 entry = &head->ctl_table[ctl_node - head->node];
410 static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
412 struct ctl_table_header *head = *phead;
413 struct ctl_table *entry = *pentry;
414 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
416 spin_lock(&sysctl_lock);
419 ctl_node = first_usable_entry(rb_next(&ctl_node->node));
420 spin_unlock(&sysctl_lock);
423 head = ctl_node->header;
424 entry = &head->ctl_table[ctl_node - head->node];
431 * sysctl_perm does NOT grant the superuser all rights automatically, because
432 * some sysctl variables are readonly even to root.
435 static int test_perm(int mode, int op)
437 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
439 else if (in_egroup_p(GLOBAL_ROOT_GID))
441 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
446 static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
448 struct ctl_table_root *root = head->root;
451 if (root->permissions)
452 mode = root->permissions(head, table);
456 return test_perm(mode, op);
459 static struct inode *proc_sys_make_inode(struct super_block *sb,
460 struct ctl_table_header *head, struct ctl_table *table)
462 struct ctl_table_root *root = head->root;
464 struct proc_inode *ei;
466 inode = new_inode(sb);
468 return ERR_PTR(-ENOMEM);
470 inode->i_ino = get_next_ino();
474 spin_lock(&sysctl_lock);
475 if (unlikely(head->unregistering)) {
476 spin_unlock(&sysctl_lock);
478 return ERR_PTR(-ENOENT);
481 ei->sysctl_entry = table;
482 hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes);
484 spin_unlock(&sysctl_lock);
486 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
487 inode->i_mode = table->mode;
488 if (!S_ISDIR(table->mode)) {
489 inode->i_mode |= S_IFREG;
490 inode->i_op = &proc_sys_inode_operations;
491 inode->i_fop = &proc_sys_file_operations;
493 inode->i_mode |= S_IFDIR;
494 inode->i_op = &proc_sys_dir_operations;
495 inode->i_fop = &proc_sys_dir_file_operations;
496 if (is_empty_dir(head))
497 make_empty_dir_inode(inode);
500 if (root->set_ownership)
501 root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
503 inode->i_uid = GLOBAL_ROOT_UID;
504 inode->i_gid = GLOBAL_ROOT_GID;
510 void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
512 spin_lock(&sysctl_lock);
513 hlist_del_init_rcu(&PROC_I(inode)->sysctl_inodes);
515 kfree_rcu(head, rcu);
516 spin_unlock(&sysctl_lock);
519 static struct ctl_table_header *grab_header(struct inode *inode)
521 struct ctl_table_header *head = PROC_I(inode)->sysctl;
523 head = &sysctl_table_root.default_set.dir.header;
524 return sysctl_head_grab(head);
527 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
530 struct ctl_table_header *head = grab_header(dir);
531 struct ctl_table_header *h = NULL;
532 const struct qstr *name = &dentry->d_name;
535 struct dentry *err = ERR_PTR(-ENOENT);
536 struct ctl_dir *ctl_dir;
540 return ERR_CAST(head);
542 ctl_dir = container_of(head, struct ctl_dir, header);
544 p = lookup_entry(&h, ctl_dir, name->name, name->len);
548 if (S_ISLNK(p->mode)) {
549 ret = sysctl_follow_link(&h, &p);
555 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
557 err = ERR_CAST(inode);
562 d_set_d_op(dentry, &proc_sys_dentry_operations);
563 d_add(dentry, inode);
567 sysctl_head_finish(h);
568 sysctl_head_finish(head);
572 static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
573 size_t count, loff_t *ppos, int write)
575 struct inode *inode = file_inode(filp);
576 struct ctl_table_header *head = grab_header(inode);
577 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
582 return PTR_ERR(head);
585 * At this point we know that the sysctl was not unregistered
586 * and won't be until we finish.
589 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
592 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
594 if (!table->proc_handler)
597 /* careful: calling conventions are nasty here */
599 error = table->proc_handler(table, write, buf, &res, ppos);
603 sysctl_head_finish(head);
608 static ssize_t proc_sys_read(struct file *filp, char __user *buf,
609 size_t count, loff_t *ppos)
611 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
614 static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
615 size_t count, loff_t *ppos)
617 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
620 static int proc_sys_open(struct inode *inode, struct file *filp)
622 struct ctl_table_header *head = grab_header(inode);
623 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
625 /* sysctl was unregistered */
627 return PTR_ERR(head);
630 filp->private_data = proc_sys_poll_event(table->poll);
632 sysctl_head_finish(head);
637 static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
639 struct inode *inode = file_inode(filp);
640 struct ctl_table_header *head = grab_header(inode);
641 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
642 unsigned int ret = DEFAULT_POLLMASK;
645 /* sysctl was unregistered */
647 return POLLERR | POLLHUP;
649 if (!table->proc_handler)
655 event = (unsigned long)filp->private_data;
656 poll_wait(filp, &table->poll->wait, wait);
658 if (event != atomic_read(&table->poll->event)) {
659 filp->private_data = proc_sys_poll_event(table->poll);
660 ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI;
664 sysctl_head_finish(head);
669 static bool proc_sys_fill_cache(struct file *file,
670 struct dir_context *ctx,
671 struct ctl_table_header *head,
672 struct ctl_table *table)
674 struct dentry *child, *dir = file->f_path.dentry;
678 unsigned type = DT_UNKNOWN;
680 qname.name = table->procname;
681 qname.len = strlen(table->procname);
682 qname.hash = full_name_hash(dir, qname.name, qname.len);
684 child = d_lookup(dir, &qname);
686 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
687 child = d_alloc_parallel(dir, &qname, &wq);
690 if (d_in_lookup(child)) {
691 inode = proc_sys_make_inode(dir->d_sb, head, table);
693 d_lookup_done(child);
697 d_set_d_op(child, &proc_sys_dentry_operations);
701 inode = d_inode(child);
703 type = inode->i_mode >> 12;
705 return dir_emit(ctx, qname.name, qname.len, ino, type);
708 static bool proc_sys_link_fill_cache(struct file *file,
709 struct dir_context *ctx,
710 struct ctl_table_header *head,
711 struct ctl_table *table)
715 head = sysctl_head_grab(head);
719 if (S_ISLNK(table->mode)) {
720 /* It is not an error if we can not follow the link ignore it */
721 int err = sysctl_follow_link(&head, &table);
726 ret = proc_sys_fill_cache(file, ctx, head, table);
728 sysctl_head_finish(head);
732 static int scan(struct ctl_table_header *head, struct ctl_table *table,
733 unsigned long *pos, struct file *file,
734 struct dir_context *ctx)
738 if ((*pos)++ < ctx->pos)
741 if (unlikely(S_ISLNK(table->mode)))
742 res = proc_sys_link_fill_cache(file, ctx, head, table);
744 res = proc_sys_fill_cache(file, ctx, head, table);
752 static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
754 struct ctl_table_header *head = grab_header(file_inode(file));
755 struct ctl_table_header *h = NULL;
756 struct ctl_table *entry;
757 struct ctl_dir *ctl_dir;
761 return PTR_ERR(head);
763 ctl_dir = container_of(head, struct ctl_dir, header);
765 if (!dir_emit_dots(file, ctx))
770 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
771 if (!scan(h, entry, &pos, file, ctx)) {
772 sysctl_head_finish(h);
777 sysctl_head_finish(head);
781 static int proc_sys_permission(struct inode *inode, int mask)
784 * sysctl entries that are not writeable,
785 * are _NOT_ writeable, capabilities or not.
787 struct ctl_table_header *head;
788 struct ctl_table *table;
791 /* Executable files are not allowed under /proc/sys/ */
792 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
795 head = grab_header(inode);
797 return PTR_ERR(head);
799 table = PROC_I(inode)->sysctl_entry;
800 if (!table) /* global root - r-xr-xr-x */
801 error = mask & MAY_WRITE ? -EACCES : 0;
802 else /* Use the permissions on the sysctl table entry */
803 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
805 sysctl_head_finish(head);
809 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
811 struct inode *inode = d_inode(dentry);
814 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
817 error = setattr_prepare(dentry, attr);
821 setattr_copy(inode, attr);
822 mark_inode_dirty(inode);
826 static int proc_sys_getattr(const struct path *path, struct kstat *stat,
827 u32 request_mask, unsigned int query_flags)
829 struct inode *inode = d_inode(path->dentry);
830 struct ctl_table_header *head = grab_header(inode);
831 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
834 return PTR_ERR(head);
836 generic_fillattr(inode, stat);
838 stat->mode = (stat->mode & S_IFMT) | table->mode;
840 sysctl_head_finish(head);
844 static const struct file_operations proc_sys_file_operations = {
845 .open = proc_sys_open,
846 .poll = proc_sys_poll,
847 .read = proc_sys_read,
848 .write = proc_sys_write,
849 .llseek = default_llseek,
852 static const struct file_operations proc_sys_dir_file_operations = {
853 .read = generic_read_dir,
854 .iterate_shared = proc_sys_readdir,
855 .llseek = generic_file_llseek,
858 static const struct inode_operations proc_sys_inode_operations = {
859 .permission = proc_sys_permission,
860 .setattr = proc_sys_setattr,
861 .getattr = proc_sys_getattr,
864 static const struct inode_operations proc_sys_dir_operations = {
865 .lookup = proc_sys_lookup,
866 .permission = proc_sys_permission,
867 .setattr = proc_sys_setattr,
868 .getattr = proc_sys_getattr,
871 static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
873 if (flags & LOOKUP_RCU)
875 return !PROC_I(d_inode(dentry))->sysctl->unregistering;
878 static int proc_sys_delete(const struct dentry *dentry)
880 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
883 static int sysctl_is_seen(struct ctl_table_header *p)
885 struct ctl_table_set *set = p->set;
887 spin_lock(&sysctl_lock);
888 if (p->unregistering)
890 else if (!set->is_seen)
893 res = set->is_seen(set);
894 spin_unlock(&sysctl_lock);
898 static int proc_sys_compare(const struct dentry *dentry,
899 unsigned int len, const char *str, const struct qstr *name)
901 struct ctl_table_header *head;
904 /* Although proc doesn't have negative dentries, rcu-walk means
905 * that inode here can be NULL */
906 /* AV: can it, indeed? */
907 inode = d_inode_rcu(dentry);
910 if (name->len != len)
912 if (memcmp(name->name, str, len))
914 head = rcu_dereference(PROC_I(inode)->sysctl);
915 return !head || !sysctl_is_seen(head);
918 static const struct dentry_operations proc_sys_dentry_operations = {
919 .d_revalidate = proc_sys_revalidate,
920 .d_delete = proc_sys_delete,
921 .d_compare = proc_sys_compare,
924 static struct ctl_dir *find_subdir(struct ctl_dir *dir,
925 const char *name, int namelen)
927 struct ctl_table_header *head;
928 struct ctl_table *entry;
930 entry = find_entry(&head, dir, name, namelen);
932 return ERR_PTR(-ENOENT);
933 if (!S_ISDIR(entry->mode))
934 return ERR_PTR(-ENOTDIR);
935 return container_of(head, struct ctl_dir, header);
938 static struct ctl_dir *new_dir(struct ctl_table_set *set,
939 const char *name, int namelen)
941 struct ctl_table *table;
943 struct ctl_node *node;
946 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
947 sizeof(struct ctl_table)*2 + namelen + 1,
952 node = (struct ctl_node *)(new + 1);
953 table = (struct ctl_table *)(node + 1);
954 new_name = (char *)(table + 2);
955 memcpy(new_name, name, namelen);
956 new_name[namelen] = '\0';
957 table[0].procname = new_name;
958 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
959 init_header(&new->header, set->dir.header.root, set, node, table);
965 * get_subdir - find or create a subdir with the specified name.
966 * @dir: Directory to create the subdirectory in
967 * @name: The name of the subdirectory to find or create
968 * @namelen: The length of name
970 * Takes a directory with an elevated reference count so we know that
971 * if we drop the lock the directory will not go away. Upon success
972 * the reference is moved from @dir to the returned subdirectory.
973 * Upon error an error code is returned and the reference on @dir is
976 static struct ctl_dir *get_subdir(struct ctl_dir *dir,
977 const char *name, int namelen)
979 struct ctl_table_set *set = dir->header.set;
980 struct ctl_dir *subdir, *new = NULL;
983 spin_lock(&sysctl_lock);
984 subdir = find_subdir(dir, name, namelen);
987 if (PTR_ERR(subdir) != -ENOENT)
990 spin_unlock(&sysctl_lock);
991 new = new_dir(set, name, namelen);
992 spin_lock(&sysctl_lock);
993 subdir = ERR_PTR(-ENOMEM);
997 /* Was the subdir added while we dropped the lock? */
998 subdir = find_subdir(dir, name, namelen);
1001 if (PTR_ERR(subdir) != -ENOENT)
1004 /* Nope. Use the our freshly made directory entry. */
1005 err = insert_header(dir, &new->header);
1006 subdir = ERR_PTR(err);
1011 subdir->header.nreg++;
1013 if (IS_ERR(subdir)) {
1014 pr_err("sysctl could not get directory: ");
1015 sysctl_print_dir(dir);
1016 pr_cont("/%*.*s %ld\n",
1017 namelen, namelen, name, PTR_ERR(subdir));
1019 drop_sysctl_table(&dir->header);
1021 drop_sysctl_table(&new->header);
1022 spin_unlock(&sysctl_lock);
1026 static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
1028 struct ctl_dir *parent;
1029 const char *procname;
1030 if (!dir->header.parent)
1032 parent = xlate_dir(set, dir->header.parent);
1035 procname = dir->header.ctl_table[0].procname;
1036 return find_subdir(parent, procname, strlen(procname));
1039 static int sysctl_follow_link(struct ctl_table_header **phead,
1040 struct ctl_table **pentry)
1042 struct ctl_table_header *head;
1043 struct ctl_table_root *root;
1044 struct ctl_table_set *set;
1045 struct ctl_table *entry;
1046 struct ctl_dir *dir;
1050 spin_lock(&sysctl_lock);
1051 root = (*pentry)->data;
1052 set = lookup_header_set(root);
1053 dir = xlate_dir(set, (*phead)->parent);
1057 const char *procname = (*pentry)->procname;
1059 entry = find_entry(&head, dir, procname, strlen(procname));
1061 if (entry && use_table(head)) {
1062 unuse_table(*phead);
1069 spin_unlock(&sysctl_lock);
1073 static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
1075 struct va_format vaf;
1078 va_start(args, fmt);
1082 pr_err("sysctl table check failed: %s/%s %pV\n",
1083 path, table->procname, &vaf);
1089 static int sysctl_check_table_array(const char *path, struct ctl_table *table)
1093 if ((table->proc_handler == proc_douintvec) ||
1094 (table->proc_handler == proc_douintvec_minmax)) {
1095 if (table->maxlen != sizeof(unsigned int))
1096 err |= sysctl_err(path, table, "array now allowed");
1102 static int sysctl_check_table(const char *path, struct ctl_table *table)
1105 for (; table->procname; table++) {
1107 err |= sysctl_err(path, table, "Not a file");
1109 if ((table->proc_handler == proc_dostring) ||
1110 (table->proc_handler == proc_dointvec) ||
1111 (table->proc_handler == proc_douintvec) ||
1112 (table->proc_handler == proc_douintvec_minmax) ||
1113 (table->proc_handler == proc_dointvec_minmax) ||
1114 (table->proc_handler == proc_dointvec_jiffies) ||
1115 (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1116 (table->proc_handler == proc_dointvec_ms_jiffies) ||
1117 (table->proc_handler == proc_doulongvec_minmax) ||
1118 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1120 err |= sysctl_err(path, table, "No data");
1122 err |= sysctl_err(path, table, "No maxlen");
1124 err |= sysctl_check_table_array(path, table);
1126 if (!table->proc_handler)
1127 err |= sysctl_err(path, table, "No proc_handler");
1129 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1130 err |= sysctl_err(path, table, "bogus .mode 0%o",
1136 static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1137 struct ctl_table_root *link_root)
1139 struct ctl_table *link_table, *entry, *link;
1140 struct ctl_table_header *links;
1141 struct ctl_node *node;
1143 int nr_entries, name_bytes;
1147 for (entry = table; entry->procname; entry++) {
1149 name_bytes += strlen(entry->procname) + 1;
1152 links = kzalloc(sizeof(struct ctl_table_header) +
1153 sizeof(struct ctl_node)*nr_entries +
1154 sizeof(struct ctl_table)*(nr_entries + 1) +
1161 node = (struct ctl_node *)(links + 1);
1162 link_table = (struct ctl_table *)(node + nr_entries);
1163 link_name = (char *)&link_table[nr_entries + 1];
1165 for (link = link_table, entry = table; entry->procname; link++, entry++) {
1166 int len = strlen(entry->procname) + 1;
1167 memcpy(link_name, entry->procname, len);
1168 link->procname = link_name;
1169 link->mode = S_IFLNK|S_IRWXUGO;
1170 link->data = link_root;
1173 init_header(links, dir->header.root, dir->header.set, node, link_table);
1174 links->nreg = nr_entries;
1179 static bool get_links(struct ctl_dir *dir,
1180 struct ctl_table *table, struct ctl_table_root *link_root)
1182 struct ctl_table_header *head;
1183 struct ctl_table *entry, *link;
1185 /* Are there links available for every entry in table? */
1186 for (entry = table; entry->procname; entry++) {
1187 const char *procname = entry->procname;
1188 link = find_entry(&head, dir, procname, strlen(procname));
1191 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1193 if (S_ISLNK(link->mode) && (link->data == link_root))
1198 /* The checks passed. Increase the registration count on the links */
1199 for (entry = table; entry->procname; entry++) {
1200 const char *procname = entry->procname;
1201 link = find_entry(&head, dir, procname, strlen(procname));
1207 static int insert_links(struct ctl_table_header *head)
1209 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1210 struct ctl_dir *core_parent = NULL;
1211 struct ctl_table_header *links;
1214 if (head->set == root_set)
1217 core_parent = xlate_dir(root_set, head->parent);
1218 if (IS_ERR(core_parent))
1221 if (get_links(core_parent, head->ctl_table, head->root))
1224 core_parent->header.nreg++;
1225 spin_unlock(&sysctl_lock);
1227 links = new_links(core_parent, head->ctl_table, head->root);
1229 spin_lock(&sysctl_lock);
1235 if (get_links(core_parent, head->ctl_table, head->root)) {
1240 err = insert_header(core_parent, links);
1244 drop_sysctl_table(&core_parent->header);
1249 * __register_sysctl_table - register a leaf sysctl table
1250 * @set: Sysctl tree to register on
1251 * @path: The path to the directory the sysctl table is in.
1252 * @table: the top-level table structure
1254 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1255 * array. A completely 0 filled entry terminates the table.
1257 * The members of the &struct ctl_table structure are used as follows:
1259 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1260 * enter a sysctl file
1262 * data - a pointer to data for use by proc_handler
1264 * maxlen - the maximum size in bytes of the data
1266 * mode - the file permissions for the /proc/sys file
1268 * child - must be %NULL.
1270 * proc_handler - the text handler routine (described below)
1272 * extra1, extra2 - extra pointers usable by the proc handler routines
1274 * Leaf nodes in the sysctl tree will be represented by a single file
1275 * under /proc; non-leaf nodes will be represented by directories.
1277 * There must be a proc_handler routine for any terminal nodes.
1278 * Several default handlers are available to cover common cases -
1280 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1281 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1282 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1284 * It is the handler's job to read the input buffer from user memory
1285 * and process it. The handler should return 0 on success.
1287 * This routine returns %NULL on a failure to register, and a pointer
1288 * to the table header on success.
1290 struct ctl_table_header *__register_sysctl_table(
1291 struct ctl_table_set *set,
1292 const char *path, struct ctl_table *table)
1294 struct ctl_table_root *root = set->dir.header.root;
1295 struct ctl_table_header *header;
1296 const char *name, *nextname;
1297 struct ctl_dir *dir;
1298 struct ctl_table *entry;
1299 struct ctl_node *node;
1302 for (entry = table; entry->procname; entry++)
1305 header = kzalloc(sizeof(struct ctl_table_header) +
1306 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1310 node = (struct ctl_node *)(header + 1);
1311 init_header(header, root, set, node, table);
1312 if (sysctl_check_table(path, table))
1315 spin_lock(&sysctl_lock);
1317 /* Reference moved down the diretory tree get_subdir */
1319 spin_unlock(&sysctl_lock);
1321 /* Find the directory for the ctl_table */
1322 for (name = path; name; name = nextname) {
1324 nextname = strchr(name, '/');
1326 namelen = nextname - name;
1329 namelen = strlen(name);
1334 dir = get_subdir(dir, name, namelen);
1339 spin_lock(&sysctl_lock);
1340 if (insert_header(dir, header))
1341 goto fail_put_dir_locked;
1343 drop_sysctl_table(&dir->header);
1344 spin_unlock(&sysctl_lock);
1348 fail_put_dir_locked:
1349 drop_sysctl_table(&dir->header);
1350 spin_unlock(&sysctl_lock);
1358 * register_sysctl - register a sysctl table
1359 * @path: The path to the directory the sysctl table is in.
1360 * @table: the table structure
1362 * Register a sysctl table. @table should be a filled in ctl_table
1363 * array. A completely 0 filled entry terminates the table.
1365 * See __register_sysctl_table for more details.
1367 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
1369 return __register_sysctl_table(&sysctl_table_root.default_set,
1372 EXPORT_SYMBOL(register_sysctl);
1375 * __register_sysctl_init() - register sysctl table to path
1376 * @path: path name for sysctl base
1377 * @table: This is the sysctl table that needs to be registered to the path
1378 * @table_name: The name of sysctl table, only used for log printing when
1379 * registration fails
1381 * The sysctl interface is used by userspace to query or modify at runtime
1382 * a predefined value set on a variable. These variables however have default
1383 * values pre-set. Code which depends on these variables will always work even
1384 * if register_sysctl() fails. If register_sysctl() fails you'd just loose the
1385 * ability to query or modify the sysctls dynamically at run time. Chances of
1386 * register_sysctl() failing on init are extremely low, and so for both reasons
1387 * this function does not return any error as it is used by initialization code.
1389 * Context: Can only be called after your respective sysctl base path has been
1390 * registered. So for instance, most base directories are registered early on
1391 * init before init levels are processed through proc_sys_init() and
1394 void __init __register_sysctl_init(const char *path, struct ctl_table *table,
1395 const char *table_name)
1397 struct ctl_table_header *hdr = register_sysctl(path, table);
1399 if (unlikely(!hdr)) {
1400 pr_err("failed when register_sysctl %s to %s\n", table_name, path);
1403 kmemleak_not_leak(hdr);
1406 static char *append_path(const char *path, char *pos, const char *name)
1409 namelen = strlen(name);
1410 if (((pos - path) + namelen + 2) >= PATH_MAX)
1412 memcpy(pos, name, namelen);
1414 pos[namelen + 1] = '\0';
1419 static int count_subheaders(struct ctl_table *table)
1422 int nr_subheaders = 0;
1423 struct ctl_table *entry;
1425 /* special case: no directory and empty directory */
1426 if (!table || !table->procname)
1429 for (entry = table; entry->procname; entry++) {
1431 nr_subheaders += count_subheaders(entry->child);
1435 return nr_subheaders + has_files;
1438 static int register_leaf_sysctl_tables(const char *path, char *pos,
1439 struct ctl_table_header ***subheader, struct ctl_table_set *set,
1440 struct ctl_table *table)
1442 struct ctl_table *ctl_table_arg = NULL;
1443 struct ctl_table *entry, *files;
1448 for (entry = table; entry->procname; entry++) {
1456 /* If there are mixed files and directories we need a new table */
1457 if (nr_dirs && nr_files) {
1458 struct ctl_table *new;
1459 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1464 ctl_table_arg = files;
1465 for (new = files, entry = table; entry->procname; entry++) {
1473 /* Register everything except a directory full of subdirectories */
1474 if (nr_files || !nr_dirs) {
1475 struct ctl_table_header *header;
1476 header = __register_sysctl_table(set, path, files);
1478 kfree(ctl_table_arg);
1482 /* Remember if we need to free the file table */
1483 header->ctl_table_arg = ctl_table_arg;
1484 **subheader = header;
1488 /* Recurse into the subdirectories. */
1489 for (entry = table; entry->procname; entry++) {
1495 err = -ENAMETOOLONG;
1496 child_pos = append_path(path, pos, entry->procname);
1500 err = register_leaf_sysctl_tables(path, child_pos, subheader,
1508 /* On failure our caller will unregister all registered subheaders */
1513 * __register_sysctl_paths - register a sysctl table hierarchy
1514 * @set: Sysctl tree to register on
1515 * @path: The path to the directory the sysctl table is in.
1516 * @table: the top-level table structure
1518 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1519 * array. A completely 0 filled entry terminates the table.
1521 * See __register_sysctl_table for more details.
1523 struct ctl_table_header *__register_sysctl_paths(
1524 struct ctl_table_set *set,
1525 const struct ctl_path *path, struct ctl_table *table)
1527 struct ctl_table *ctl_table_arg = table;
1528 int nr_subheaders = count_subheaders(table);
1529 struct ctl_table_header *header = NULL, **subheaders, **subheader;
1530 const struct ctl_path *component;
1531 char *new_path, *pos;
1533 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1538 for (component = path; component->procname; component++) {
1539 pos = append_path(new_path, pos, component->procname);
1543 while (table->procname && table->child && !table[1].procname) {
1544 pos = append_path(new_path, pos, table->procname);
1547 table = table->child;
1549 if (nr_subheaders == 1) {
1550 header = __register_sysctl_table(set, new_path, table);
1552 header->ctl_table_arg = ctl_table_arg;
1554 header = kzalloc(sizeof(*header) +
1555 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1559 subheaders = (struct ctl_table_header **) (header + 1);
1560 subheader = subheaders;
1561 header->ctl_table_arg = ctl_table_arg;
1563 if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1565 goto err_register_leaves;
1572 err_register_leaves:
1573 while (subheader > subheaders) {
1574 struct ctl_table_header *subh = *(--subheader);
1575 struct ctl_table *table = subh->ctl_table_arg;
1576 unregister_sysctl_table(subh);
1585 * register_sysctl_table_path - register a sysctl table hierarchy
1586 * @path: The path to the directory the sysctl table is in.
1587 * @table: the top-level table structure
1589 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1590 * array. A completely 0 filled entry terminates the table.
1592 * See __register_sysctl_paths for more details.
1594 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1595 struct ctl_table *table)
1597 return __register_sysctl_paths(&sysctl_table_root.default_set,
1600 EXPORT_SYMBOL(register_sysctl_paths);
1603 * register_sysctl_table - register a sysctl table hierarchy
1604 * @table: the top-level table structure
1606 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1607 * array. A completely 0 filled entry terminates the table.
1609 * See register_sysctl_paths for more details.
1611 struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1613 static const struct ctl_path null_path[] = { {} };
1615 return register_sysctl_paths(null_path, table);
1617 EXPORT_SYMBOL(register_sysctl_table);
1619 static void put_links(struct ctl_table_header *header)
1621 struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1622 struct ctl_table_root *root = header->root;
1623 struct ctl_dir *parent = header->parent;
1624 struct ctl_dir *core_parent;
1625 struct ctl_table *entry;
1627 if (header->set == root_set)
1630 core_parent = xlate_dir(root_set, parent);
1631 if (IS_ERR(core_parent))
1634 for (entry = header->ctl_table; entry->procname; entry++) {
1635 struct ctl_table_header *link_head;
1636 struct ctl_table *link;
1637 const char *name = entry->procname;
1639 link = find_entry(&link_head, core_parent, name, strlen(name));
1641 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1642 (S_ISLNK(link->mode) && (link->data == root)))) {
1643 drop_sysctl_table(link_head);
1646 pr_err("sysctl link missing during unregister: ");
1647 sysctl_print_dir(parent);
1648 pr_cont("/%s\n", name);
1653 static void drop_sysctl_table(struct ctl_table_header *header)
1655 struct ctl_dir *parent = header->parent;
1662 start_unregistering(header);
1665 if (!--header->count)
1666 kfree_rcu(header, rcu);
1669 drop_sysctl_table(&parent->header);
1673 * unregister_sysctl_table - unregister a sysctl table hierarchy
1674 * @header: the header returned from register_sysctl_table
1676 * Unregisters the sysctl table and all children. proc entries may not
1677 * actually be removed until they are no longer used by anyone.
1679 void unregister_sysctl_table(struct ctl_table_header * header)
1687 nr_subheaders = count_subheaders(header->ctl_table_arg);
1688 if (unlikely(nr_subheaders > 1)) {
1689 struct ctl_table_header **subheaders;
1692 subheaders = (struct ctl_table_header **)(header + 1);
1693 for (i = nr_subheaders -1; i >= 0; i--) {
1694 struct ctl_table_header *subh = subheaders[i];
1695 struct ctl_table *table = subh->ctl_table_arg;
1696 unregister_sysctl_table(subh);
1703 spin_lock(&sysctl_lock);
1704 drop_sysctl_table(header);
1705 spin_unlock(&sysctl_lock);
1707 EXPORT_SYMBOL(unregister_sysctl_table);
1709 void setup_sysctl_set(struct ctl_table_set *set,
1710 struct ctl_table_root *root,
1711 int (*is_seen)(struct ctl_table_set *))
1713 memset(set, 0, sizeof(*set));
1714 set->is_seen = is_seen;
1715 init_header(&set->dir.header, root, set, NULL, root_table);
1718 void retire_sysctl_set(struct ctl_table_set *set)
1720 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1723 int __init proc_sys_init(void)
1725 struct proc_dir_entry *proc_sys_root;
1727 proc_sys_root = proc_mkdir("sys", NULL);
1728 proc_sys_root->proc_iops = &proc_sys_dir_operations;
1729 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1730 proc_sys_root->nlink = 0;
1732 return sysctl_init();