v4.19.13 snapshot.
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
new file mode 100644
index 0000000..4d598a3
--- /dev/null
+++ b/fs/proc/proc_sysctl.c
@@ -0,0 +1,1699 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * /proc/sys support
+ */
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <linux/poll.h>
+#include <linux/proc_fs.h>
+#include <linux/printk.h>
+#include <linux/security.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/namei.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include "internal.h"
+
+static const struct dentry_operations proc_sys_dentry_operations;
+static const struct file_operations proc_sys_file_operations;
+static const struct inode_operations proc_sys_inode_operations;
+static const struct file_operations proc_sys_dir_file_operations;
+static const struct inode_operations proc_sys_dir_operations;
+
+/* Support for permanently empty directories */
+
+struct ctl_table sysctl_mount_point[] = {
+ { }
+};
+
+static bool is_empty_dir(struct ctl_table_header *head)
+{
+ return head->ctl_table[0].child == sysctl_mount_point;
+}
+
+static void set_empty_dir(struct ctl_dir *dir)
+{
+ dir->header.ctl_table[0].child = sysctl_mount_point;
+}
+
+static void clear_empty_dir(struct ctl_dir *dir)
+
+{
+ dir->header.ctl_table[0].child = NULL;
+}
+
+void proc_sys_poll_notify(struct ctl_table_poll *poll)
+{
+ if (!poll)
+ return;
+
+ atomic_inc(&poll->event);
+ wake_up_interruptible(&poll->wait);
+}
+
+static struct ctl_table root_table[] = {
+ {
+ .procname = "",
+ .mode = S_IFDIR|S_IRUGO|S_IXUGO,
+ },
+ { }
+};
+static struct ctl_table_root sysctl_table_root = {
+ .default_set.dir.header = {
+ {{.count = 1,
+ .nreg = 1,
+ .ctl_table = root_table }},
+ .ctl_table_arg = root_table,
+ .root = &sysctl_table_root,
+ .set = &sysctl_table_root.default_set,
+ },
+};
+
+static DEFINE_SPINLOCK(sysctl_lock);
+
+static void drop_sysctl_table(struct ctl_table_header *header);
+static int sysctl_follow_link(struct ctl_table_header **phead,
+ struct ctl_table **pentry);
+static int insert_links(struct ctl_table_header *head);
+static void put_links(struct ctl_table_header *header);
+
+static void sysctl_print_dir(struct ctl_dir *dir)
+{
+ if (dir->header.parent)
+ sysctl_print_dir(dir->header.parent);
+ pr_cont("%s/", dir->header.ctl_table[0].procname);
+}
+
+static int namecmp(const char *name1, int len1, const char *name2, int len2)
+{
+ int minlen;
+ int cmp;
+
+ minlen = len1;
+ if (minlen > len2)
+ minlen = len2;
+
+ cmp = memcmp(name1, name2, minlen);
+ if (cmp == 0)
+ cmp = len1 - len2;
+ return cmp;
+}
+
+/* Called under sysctl_lock */
+static struct ctl_table *find_entry(struct ctl_table_header **phead,
+ struct ctl_dir *dir, const char *name, int namelen)
+{
+ struct ctl_table_header *head;
+ struct ctl_table *entry;
+ struct rb_node *node = dir->root.rb_node;
+
+ while (node)
+ {
+ struct ctl_node *ctl_node;
+ const char *procname;
+ int cmp;
+
+ ctl_node = rb_entry(node, struct ctl_node, node);
+ head = ctl_node->header;
+ entry = &head->ctl_table[ctl_node - head->node];
+ procname = entry->procname;
+
+ cmp = namecmp(name, namelen, procname, strlen(procname));
+ if (cmp < 0)
+ node = node->rb_left;
+ else if (cmp > 0)
+ node = node->rb_right;
+ else {
+ *phead = head;
+ return entry;
+ }
+ }
+ return NULL;
+}
+
+static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
+{
+ struct rb_node *node = &head->node[entry - head->ctl_table].node;
+ struct rb_node **p = &head->parent->root.rb_node;
+ struct rb_node *parent = NULL;
+ const char *name = entry->procname;
+ int namelen = strlen(name);
+
+ while (*p) {
+ struct ctl_table_header *parent_head;
+ struct ctl_table *parent_entry;
+ struct ctl_node *parent_node;
+ const char *parent_name;
+ int cmp;
+
+ parent = *p;
+ parent_node = rb_entry(parent, struct ctl_node, node);
+ parent_head = parent_node->header;
+ parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
+ parent_name = parent_entry->procname;
+
+ cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
+ if (cmp < 0)
+ p = &(*p)->rb_left;
+ else if (cmp > 0)
+ p = &(*p)->rb_right;
+ else {
+ pr_err("sysctl duplicate entry: ");
+ sysctl_print_dir(head->parent);
+ pr_cont("/%s\n", entry->procname);
+ return -EEXIST;
+ }
+ }
+
+ rb_link_node(node, parent, p);
+ rb_insert_color(node, &head->parent->root);
+ return 0;
+}
+
+static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
+{
+ struct rb_node *node = &head->node[entry - head->ctl_table].node;
+
+ rb_erase(node, &head->parent->root);
+}
+
+static void init_header(struct ctl_table_header *head,
+ struct ctl_table_root *root, struct ctl_table_set *set,
+ struct ctl_node *node, struct ctl_table *table)
+{
+ head->ctl_table = table;
+ head->ctl_table_arg = table;
+ head->used = 0;
+ head->count = 1;
+ head->nreg = 1;
+ head->unregistering = NULL;
+ head->root = root;
+ head->set = set;
+ head->parent = NULL;
+ head->node = node;
+ INIT_HLIST_HEAD(&head->inodes);
+ if (node) {
+ struct ctl_table *entry;
+ for (entry = table; entry->procname; entry++, node++)
+ node->header = head;
+ }
+}
+
+static void erase_header(struct ctl_table_header *head)
+{
+ struct ctl_table *entry;
+ for (entry = head->ctl_table; entry->procname; entry++)
+ erase_entry(head, entry);
+}
+
+static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
+{
+ struct ctl_table *entry;
+ int err;
+
+ /* Is this a permanently empty directory? */
+ if (is_empty_dir(&dir->header))
+ return -EROFS;
+
+ /* Am I creating a permanently empty directory? */
+ if (header->ctl_table == sysctl_mount_point) {
+ if (!RB_EMPTY_ROOT(&dir->root))
+ return -EINVAL;
+ set_empty_dir(dir);
+ }
+
+ dir->header.nreg++;
+ header->parent = dir;
+ err = insert_links(header);
+ if (err)
+ goto fail_links;
+ for (entry = header->ctl_table; entry->procname; entry++) {
+ err = insert_entry(header, entry);
+ if (err)
+ goto fail;
+ }
+ return 0;
+fail:
+ erase_header(header);
+ put_links(header);
+fail_links:
+ if (header->ctl_table == sysctl_mount_point)
+ clear_empty_dir(dir);
+ header->parent = NULL;
+ drop_sysctl_table(&dir->header);
+ return err;
+}
+
+/* called under sysctl_lock */
+static int use_table(struct ctl_table_header *p)
+{
+ if (unlikely(p->unregistering))
+ return 0;
+ p->used++;
+ return 1;
+}
+
+/* called under sysctl_lock */
+static void unuse_table(struct ctl_table_header *p)
+{
+ if (!--p->used)
+ if (unlikely(p->unregistering))
+ complete(p->unregistering);
+}
+
+static void proc_sys_prune_dcache(struct ctl_table_header *head)
+{
+ struct inode *inode;
+ struct proc_inode *ei;
+ struct hlist_node *node;
+ struct super_block *sb;
+
+ rcu_read_lock();
+ for (;;) {
+ node = hlist_first_rcu(&head->inodes);
+ if (!node)
+ break;
+ ei = hlist_entry(node, struct proc_inode, sysctl_inodes);
+ spin_lock(&sysctl_lock);
+ hlist_del_init_rcu(&ei->sysctl_inodes);
+ spin_unlock(&sysctl_lock);
+
+ inode = &ei->vfs_inode;
+ sb = inode->i_sb;
+ if (!atomic_inc_not_zero(&sb->s_active))
+ continue;
+ inode = igrab(inode);
+ rcu_read_unlock();
+ if (unlikely(!inode)) {
+ deactivate_super(sb);
+ rcu_read_lock();
+ continue;
+ }
+
+ d_prune_aliases(inode);
+ iput(inode);
+ deactivate_super(sb);
+
+ rcu_read_lock();
+ }
+ rcu_read_unlock();
+}
+
+/* called under sysctl_lock, will reacquire if has to wait */
+static void start_unregistering(struct ctl_table_header *p)
+{
+ /*
+ * if p->used is 0, nobody will ever touch that entry again;
+ * we'll eliminate all paths to it before dropping sysctl_lock
+ */
+ if (unlikely(p->used)) {
+ struct completion wait;
+ init_completion(&wait);
+ p->unregistering = &wait;
+ spin_unlock(&sysctl_lock);
+ wait_for_completion(&wait);
+ } else {
+ /* anything non-NULL; we'll never dereference it */
+ p->unregistering = ERR_PTR(-EINVAL);
+ spin_unlock(&sysctl_lock);
+ }
+ /*
+ * Prune dentries for unregistered sysctls: namespaced sysctls
+ * can have duplicate names and contaminate dcache very badly.
+ */
+ proc_sys_prune_dcache(p);
+ /*
+ * do not remove from the list until nobody holds it; walking the
+ * list in do_sysctl() relies on that.
+ */
+ spin_lock(&sysctl_lock);
+ erase_header(p);
+}
+
+static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
+{
+ BUG_ON(!head);
+ spin_lock(&sysctl_lock);
+ if (!use_table(head))
+ head = ERR_PTR(-ENOENT);
+ spin_unlock(&sysctl_lock);
+ return head;
+}
+
+static void sysctl_head_finish(struct ctl_table_header *head)
+{
+ if (!head)
+ return;
+ spin_lock(&sysctl_lock);
+ unuse_table(head);
+ spin_unlock(&sysctl_lock);
+}
+
+static struct ctl_table_set *
+lookup_header_set(struct ctl_table_root *root)
+{
+ struct ctl_table_set *set = &root->default_set;
+ if (root->lookup)
+ set = root->lookup(root);
+ return set;
+}
+
+static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
+ struct ctl_dir *dir,
+ const char *name, int namelen)
+{
+ struct ctl_table_header *head;
+ struct ctl_table *entry;
+
+ spin_lock(&sysctl_lock);
+ entry = find_entry(&head, dir, name, namelen);
+ if (entry && use_table(head))
+ *phead = head;
+ else
+ entry = NULL;
+ spin_unlock(&sysctl_lock);
+ return entry;
+}
+
+static struct ctl_node *first_usable_entry(struct rb_node *node)
+{
+ struct ctl_node *ctl_node;
+
+ for (;node; node = rb_next(node)) {
+ ctl_node = rb_entry(node, struct ctl_node, node);
+ if (use_table(ctl_node->header))
+ return ctl_node;
+ }
+ return NULL;
+}
+
+static void first_entry(struct ctl_dir *dir,
+ struct ctl_table_header **phead, struct ctl_table **pentry)
+{
+ struct ctl_table_header *head = NULL;
+ struct ctl_table *entry = NULL;
+ struct ctl_node *ctl_node;
+
+ spin_lock(&sysctl_lock);
+ ctl_node = first_usable_entry(rb_first(&dir->root));
+ spin_unlock(&sysctl_lock);
+ if (ctl_node) {
+ head = ctl_node->header;
+ entry = &head->ctl_table[ctl_node - head->node];
+ }
+ *phead = head;
+ *pentry = entry;
+}
+
+static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
+{
+ struct ctl_table_header *head = *phead;
+ struct ctl_table *entry = *pentry;
+ struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
+
+ spin_lock(&sysctl_lock);
+ unuse_table(head);
+
+ ctl_node = first_usable_entry(rb_next(&ctl_node->node));
+ spin_unlock(&sysctl_lock);
+ head = NULL;
+ if (ctl_node) {
+ head = ctl_node->header;
+ entry = &head->ctl_table[ctl_node - head->node];
+ }
+ *phead = head;
+ *pentry = entry;
+}
+
+/*
+ * sysctl_perm does NOT grant the superuser all rights automatically, because
+ * some sysctl variables are readonly even to root.
+ */
+
+static int test_perm(int mode, int op)
+{
+ if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
+ mode >>= 6;
+ else if (in_egroup_p(GLOBAL_ROOT_GID))
+ mode >>= 3;
+ if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
+ return 0;
+ return -EACCES;
+}
+
+static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
+{
+ struct ctl_table_root *root = head->root;
+ int mode;
+
+ if (root->permissions)
+ mode = root->permissions(head, table);
+ else
+ mode = table->mode;
+
+ return test_perm(mode, op);
+}
+
+static struct inode *proc_sys_make_inode(struct super_block *sb,
+ struct ctl_table_header *head, struct ctl_table *table)
+{
+ struct ctl_table_root *root = head->root;
+ struct inode *inode;
+ struct proc_inode *ei;
+
+ inode = new_inode(sb);
+ if (!inode)
+ return ERR_PTR(-ENOMEM);
+
+ inode->i_ino = get_next_ino();
+
+ ei = PROC_I(inode);
+
+ spin_lock(&sysctl_lock);
+ if (unlikely(head->unregistering)) {
+ spin_unlock(&sysctl_lock);
+ iput(inode);
+ return ERR_PTR(-ENOENT);
+ }
+ ei->sysctl = head;
+ ei->sysctl_entry = table;
+ hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes);
+ head->count++;
+ spin_unlock(&sysctl_lock);
+
+ inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
+ inode->i_mode = table->mode;
+ if (!S_ISDIR(table->mode)) {
+ inode->i_mode |= S_IFREG;
+ inode->i_op = &proc_sys_inode_operations;
+ inode->i_fop = &proc_sys_file_operations;
+ } else {
+ inode->i_mode |= S_IFDIR;
+ inode->i_op = &proc_sys_dir_operations;
+ inode->i_fop = &proc_sys_dir_file_operations;
+ if (is_empty_dir(head))
+ make_empty_dir_inode(inode);
+ }
+
+ if (root->set_ownership)
+ root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
+
+ return inode;
+}
+
+void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
+{
+ spin_lock(&sysctl_lock);
+ hlist_del_init_rcu(&PROC_I(inode)->sysctl_inodes);
+ if (!--head->count)
+ kfree_rcu(head, rcu);
+ spin_unlock(&sysctl_lock);
+}
+
+static struct ctl_table_header *grab_header(struct inode *inode)
+{
+ struct ctl_table_header *head = PROC_I(inode)->sysctl;
+ if (!head)
+ head = &sysctl_table_root.default_set.dir.header;
+ return sysctl_head_grab(head);
+}
+
+static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
+ unsigned int flags)
+{
+ struct ctl_table_header *head = grab_header(dir);
+ struct ctl_table_header *h = NULL;
+ const struct qstr *name = &dentry->d_name;
+ struct ctl_table *p;
+ struct inode *inode;
+ struct dentry *err = ERR_PTR(-ENOENT);
+ struct ctl_dir *ctl_dir;
+ int ret;
+
+ if (IS_ERR(head))
+ return ERR_CAST(head);
+
+ ctl_dir = container_of(head, struct ctl_dir, header);
+
+ p = lookup_entry(&h, ctl_dir, name->name, name->len);
+ if (!p)
+ goto out;
+
+ if (S_ISLNK(p->mode)) {
+ ret = sysctl_follow_link(&h, &p);
+ err = ERR_PTR(ret);
+ if (ret)
+ goto out;
+ }
+
+ inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
+ if (IS_ERR(inode)) {
+ err = ERR_CAST(inode);
+ goto out;
+ }
+
+ d_set_d_op(dentry, &proc_sys_dentry_operations);
+ err = d_splice_alias(inode, dentry);
+
+out:
+ if (h)
+ sysctl_head_finish(h);
+ sysctl_head_finish(head);
+ return err;
+}
+
+static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
+ size_t count, loff_t *ppos, int write)
+{
+ struct inode *inode = file_inode(filp);
+ struct ctl_table_header *head = grab_header(inode);
+ struct ctl_table *table = PROC_I(inode)->sysctl_entry;
+ ssize_t error;
+ size_t res;
+
+ if (IS_ERR(head))
+ return PTR_ERR(head);
+
+ /*
+ * At this point we know that the sysctl was not unregistered
+ * and won't be until we finish.
+ */
+ error = -EPERM;
+ if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
+ goto out;
+
+ /* if that can happen at all, it should be -EINVAL, not -EISDIR */
+ error = -EINVAL;
+ if (!table->proc_handler)
+ goto out;
+
+ /* careful: calling conventions are nasty here */
+ res = count;
+ error = table->proc_handler(table, write, buf, &res, ppos);
+ if (!error)
+ error = res;
+out:
+ sysctl_head_finish(head);
+
+ return error;
+}
+
+static ssize_t proc_sys_read(struct file *filp, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
+}
+
+static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
+}
+
+static int proc_sys_open(struct inode *inode, struct file *filp)
+{
+ struct ctl_table_header *head = grab_header(inode);
+ struct ctl_table *table = PROC_I(inode)->sysctl_entry;
+
+ /* sysctl was unregistered */
+ if (IS_ERR(head))
+ return PTR_ERR(head);
+
+ if (table->poll)
+ filp->private_data = proc_sys_poll_event(table->poll);
+
+ sysctl_head_finish(head);
+
+ return 0;
+}
+
+static __poll_t proc_sys_poll(struct file *filp, poll_table *wait)
+{
+ struct inode *inode = file_inode(filp);
+ struct ctl_table_header *head = grab_header(inode);
+ struct ctl_table *table = PROC_I(inode)->sysctl_entry;
+ __poll_t ret = DEFAULT_POLLMASK;
+ unsigned long event;
+
+ /* sysctl was unregistered */
+ if (IS_ERR(head))
+ return EPOLLERR | EPOLLHUP;
+
+ if (!table->proc_handler)
+ goto out;
+
+ if (!table->poll)
+ goto out;
+
+ event = (unsigned long)filp->private_data;
+ poll_wait(filp, &table->poll->wait, wait);
+
+ if (event != atomic_read(&table->poll->event)) {
+ filp->private_data = proc_sys_poll_event(table->poll);
+ ret = EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI;
+ }
+
+out:
+ sysctl_head_finish(head);
+
+ return ret;
+}
+
+static bool proc_sys_fill_cache(struct file *file,
+ struct dir_context *ctx,
+ struct ctl_table_header *head,
+ struct ctl_table *table)
+{
+ struct dentry *child, *dir = file->f_path.dentry;
+ struct inode *inode;
+ struct qstr qname;
+ ino_t ino = 0;
+ unsigned type = DT_UNKNOWN;
+
+ qname.name = table->procname;
+ qname.len = strlen(table->procname);
+ qname.hash = full_name_hash(dir, qname.name, qname.len);
+
+ child = d_lookup(dir, &qname);
+ if (!child) {
+ DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+ child = d_alloc_parallel(dir, &qname, &wq);
+ if (IS_ERR(child))
+ return false;
+ if (d_in_lookup(child)) {
+ struct dentry *res;
+ inode = proc_sys_make_inode(dir->d_sb, head, table);
+ if (IS_ERR(inode)) {
+ d_lookup_done(child);
+ dput(child);
+ return false;
+ }
+ d_set_d_op(child, &proc_sys_dentry_operations);
+ res = d_splice_alias(inode, child);
+ d_lookup_done(child);
+ if (unlikely(res)) {
+ if (IS_ERR(res)) {
+ dput(child);
+ return false;
+ }
+ dput(child);
+ child = res;
+ }
+ }
+ }
+ inode = d_inode(child);
+ ino = inode->i_ino;
+ type = inode->i_mode >> 12;
+ dput(child);
+ return dir_emit(ctx, qname.name, qname.len, ino, type);
+}
+
+static bool proc_sys_link_fill_cache(struct file *file,
+ struct dir_context *ctx,
+ struct ctl_table_header *head,
+ struct ctl_table *table)
+{
+ bool ret = true;
+
+ head = sysctl_head_grab(head);
+ if (IS_ERR(head))
+ return false;
+
+ /* It is not an error if we can not follow the link ignore it */
+ if (sysctl_follow_link(&head, &table))
+ goto out;
+
+ ret = proc_sys_fill_cache(file, ctx, head, table);
+out:
+ sysctl_head_finish(head);
+ return ret;
+}
+
+static int scan(struct ctl_table_header *head, struct ctl_table *table,
+ unsigned long *pos, struct file *file,
+ struct dir_context *ctx)
+{
+ bool res;
+
+ if ((*pos)++ < ctx->pos)
+ return true;
+
+ if (unlikely(S_ISLNK(table->mode)))
+ res = proc_sys_link_fill_cache(file, ctx, head, table);
+ else
+ res = proc_sys_fill_cache(file, ctx, head, table);
+
+ if (res)
+ ctx->pos = *pos;
+
+ return res;
+}
+
+static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
+{
+ struct ctl_table_header *head = grab_header(file_inode(file));
+ struct ctl_table_header *h = NULL;
+ struct ctl_table *entry;
+ struct ctl_dir *ctl_dir;
+ unsigned long pos;
+
+ if (IS_ERR(head))
+ return PTR_ERR(head);
+
+ ctl_dir = container_of(head, struct ctl_dir, header);
+
+ if (!dir_emit_dots(file, ctx))
+ goto out;
+
+ pos = 2;
+
+ for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
+ if (!scan(h, entry, &pos, file, ctx)) {
+ sysctl_head_finish(h);
+ break;
+ }
+ }
+out:
+ sysctl_head_finish(head);
+ return 0;
+}
+
+static int proc_sys_permission(struct inode *inode, int mask)
+{
+ /*
+ * sysctl entries that are not writeable,
+ * are _NOT_ writeable, capabilities or not.
+ */
+ struct ctl_table_header *head;
+ struct ctl_table *table;
+ int error;
+
+ /* Executable files are not allowed under /proc/sys/ */
+ if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
+ return -EACCES;
+
+ head = grab_header(inode);
+ if (IS_ERR(head))
+ return PTR_ERR(head);
+
+ table = PROC_I(inode)->sysctl_entry;
+ if (!table) /* global root - r-xr-xr-x */
+ error = mask & MAY_WRITE ? -EACCES : 0;
+ else /* Use the permissions on the sysctl table entry */
+ error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
+
+ sysctl_head_finish(head);
+ return error;
+}
+
+static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ struct inode *inode = d_inode(dentry);
+ int error;
+
+ if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
+ return -EPERM;
+
+ error = setattr_prepare(dentry, attr);
+ if (error)
+ return error;
+
+ setattr_copy(inode, attr);
+ mark_inode_dirty(inode);
+ return 0;
+}
+
+static int proc_sys_getattr(const struct path *path, struct kstat *stat,
+ u32 request_mask, unsigned int query_flags)
+{
+ struct inode *inode = d_inode(path->dentry);
+ struct ctl_table_header *head = grab_header(inode);
+ struct ctl_table *table = PROC_I(inode)->sysctl_entry;
+
+ if (IS_ERR(head))
+ return PTR_ERR(head);
+
+ generic_fillattr(inode, stat);
+ if (table)
+ stat->mode = (stat->mode & S_IFMT) | table->mode;
+
+ sysctl_head_finish(head);
+ return 0;
+}
+
+static const struct file_operations proc_sys_file_operations = {
+ .open = proc_sys_open,
+ .poll = proc_sys_poll,
+ .read = proc_sys_read,
+ .write = proc_sys_write,
+ .llseek = default_llseek,
+};
+
+static const struct file_operations proc_sys_dir_file_operations = {
+ .read = generic_read_dir,
+ .iterate_shared = proc_sys_readdir,
+ .llseek = generic_file_llseek,
+};
+
+static const struct inode_operations proc_sys_inode_operations = {
+ .permission = proc_sys_permission,
+ .setattr = proc_sys_setattr,
+ .getattr = proc_sys_getattr,
+};
+
+static const struct inode_operations proc_sys_dir_operations = {
+ .lookup = proc_sys_lookup,
+ .permission = proc_sys_permission,
+ .setattr = proc_sys_setattr,
+ .getattr = proc_sys_getattr,
+};
+
+static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ if (flags & LOOKUP_RCU)
+ return -ECHILD;
+ return !PROC_I(d_inode(dentry))->sysctl->unregistering;
+}
+
+static int proc_sys_delete(const struct dentry *dentry)
+{
+ return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
+}
+
+static int sysctl_is_seen(struct ctl_table_header *p)
+{
+ struct ctl_table_set *set = p->set;
+ int res;
+ spin_lock(&sysctl_lock);
+ if (p->unregistering)
+ res = 0;
+ else if (!set->is_seen)
+ res = 1;
+ else
+ res = set->is_seen(set);
+ spin_unlock(&sysctl_lock);
+ return res;
+}
+
+static int proc_sys_compare(const struct dentry *dentry,
+ unsigned int len, const char *str, const struct qstr *name)
+{
+ struct ctl_table_header *head;
+ struct inode *inode;
+
+ /* Although proc doesn't have negative dentries, rcu-walk means
+ * that inode here can be NULL */
+ /* AV: can it, indeed? */
+ inode = d_inode_rcu(dentry);
+ if (!inode)
+ return 1;
+ if (name->len != len)
+ return 1;
+ if (memcmp(name->name, str, len))
+ return 1;
+ head = rcu_dereference(PROC_I(inode)->sysctl);
+ return !head || !sysctl_is_seen(head);
+}
+
+static const struct dentry_operations proc_sys_dentry_operations = {
+ .d_revalidate = proc_sys_revalidate,
+ .d_delete = proc_sys_delete,
+ .d_compare = proc_sys_compare,
+};
+
+static struct ctl_dir *find_subdir(struct ctl_dir *dir,
+ const char *name, int namelen)
+{
+ struct ctl_table_header *head;
+ struct ctl_table *entry;
+
+ entry = find_entry(&head, dir, name, namelen);
+ if (!entry)
+ return ERR_PTR(-ENOENT);
+ if (!S_ISDIR(entry->mode))
+ return ERR_PTR(-ENOTDIR);
+ return container_of(head, struct ctl_dir, header);
+}
+
+static struct ctl_dir *new_dir(struct ctl_table_set *set,
+ const char *name, int namelen)
+{
+ struct ctl_table *table;
+ struct ctl_dir *new;
+ struct ctl_node *node;
+ char *new_name;
+
+ new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
+ sizeof(struct ctl_table)*2 + namelen + 1,
+ GFP_KERNEL);
+ if (!new)
+ return NULL;
+
+ node = (struct ctl_node *)(new + 1);
+ table = (struct ctl_table *)(node + 1);
+ new_name = (char *)(table + 2);
+ memcpy(new_name, name, namelen);
+ new_name[namelen] = '\0';
+ table[0].procname = new_name;
+ table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
+ init_header(&new->header, set->dir.header.root, set, node, table);
+
+ return new;
+}
+
+/**
+ * get_subdir - find or create a subdir with the specified name.
+ * @dir: Directory to create the subdirectory in
+ * @name: The name of the subdirectory to find or create
+ * @namelen: The length of name
+ *
+ * Takes a directory with an elevated reference count so we know that
+ * if we drop the lock the directory will not go away. Upon success
+ * the reference is moved from @dir to the returned subdirectory.
+ * Upon error an error code is returned and the reference on @dir is
+ * simply dropped.
+ */
+static struct ctl_dir *get_subdir(struct ctl_dir *dir,
+ const char *name, int namelen)
+{
+ struct ctl_table_set *set = dir->header.set;
+ struct ctl_dir *subdir, *new = NULL;
+ int err;
+
+ spin_lock(&sysctl_lock);
+ subdir = find_subdir(dir, name, namelen);
+ if (!IS_ERR(subdir))
+ goto found;
+ if (PTR_ERR(subdir) != -ENOENT)
+ goto failed;
+
+ spin_unlock(&sysctl_lock);
+ new = new_dir(set, name, namelen);
+ spin_lock(&sysctl_lock);
+ subdir = ERR_PTR(-ENOMEM);
+ if (!new)
+ goto failed;
+
+ /* Was the subdir added while we dropped the lock? */
+ subdir = find_subdir(dir, name, namelen);
+ if (!IS_ERR(subdir))
+ goto found;
+ if (PTR_ERR(subdir) != -ENOENT)
+ goto failed;
+
+ /* Nope. Use the our freshly made directory entry. */
+ err = insert_header(dir, &new->header);
+ subdir = ERR_PTR(err);
+ if (err)
+ goto failed;
+ subdir = new;
+found:
+ subdir->header.nreg++;
+failed:
+ if (IS_ERR(subdir)) {
+ pr_err("sysctl could not get directory: ");
+ sysctl_print_dir(dir);
+ pr_cont("/%*.*s %ld\n",
+ namelen, namelen, name, PTR_ERR(subdir));
+ }
+ drop_sysctl_table(&dir->header);
+ if (new)
+ drop_sysctl_table(&new->header);
+ spin_unlock(&sysctl_lock);
+ return subdir;
+}
+
+static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
+{
+ struct ctl_dir *parent;
+ const char *procname;
+ if (!dir->header.parent)
+ return &set->dir;
+ parent = xlate_dir(set, dir->header.parent);
+ if (IS_ERR(parent))
+ return parent;
+ procname = dir->header.ctl_table[0].procname;
+ return find_subdir(parent, procname, strlen(procname));
+}
+
+static int sysctl_follow_link(struct ctl_table_header **phead,
+ struct ctl_table **pentry)
+{
+ struct ctl_table_header *head;
+ struct ctl_table_root *root;
+ struct ctl_table_set *set;
+ struct ctl_table *entry;
+ struct ctl_dir *dir;
+ int ret;
+
+ ret = 0;
+ spin_lock(&sysctl_lock);
+ root = (*pentry)->data;
+ set = lookup_header_set(root);
+ dir = xlate_dir(set, (*phead)->parent);
+ if (IS_ERR(dir))
+ ret = PTR_ERR(dir);
+ else {
+ const char *procname = (*pentry)->procname;
+ head = NULL;
+ entry = find_entry(&head, dir, procname, strlen(procname));
+ ret = -ENOENT;
+ if (entry && use_table(head)) {
+ unuse_table(*phead);
+ *phead = head;
+ *pentry = entry;
+ ret = 0;
+ }
+ }
+
+ spin_unlock(&sysctl_lock);
+ return ret;
+}
+
+static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
+{
+ struct va_format vaf;
+ va_list args;
+
+ va_start(args, fmt);
+ vaf.fmt = fmt;
+ vaf.va = &args;
+
+ pr_err("sysctl table check failed: %s/%s %pV\n",
+ path, table->procname, &vaf);
+
+ va_end(args);
+ return -EINVAL;
+}
+
+static int sysctl_check_table_array(const char *path, struct ctl_table *table)
+{
+ int err = 0;
+
+ if ((table->proc_handler == proc_douintvec) ||
+ (table->proc_handler == proc_douintvec_minmax)) {
+ if (table->maxlen != sizeof(unsigned int))
+ err |= sysctl_err(path, table, "array not allowed");
+ }
+
+ return err;
+}
+
+static int sysctl_check_table(const char *path, struct ctl_table *table)
+{
+ int err = 0;
+ for (; table->procname; table++) {
+ if (table->child)
+ err |= sysctl_err(path, table, "Not a file");
+
+ if ((table->proc_handler == proc_dostring) ||
+ (table->proc_handler == proc_dointvec) ||
+ (table->proc_handler == proc_douintvec) ||
+ (table->proc_handler == proc_douintvec_minmax) ||
+ (table->proc_handler == proc_dointvec_minmax) ||
+ (table->proc_handler == proc_dointvec_jiffies) ||
+ (table->proc_handler == proc_dointvec_userhz_jiffies) ||
+ (table->proc_handler == proc_dointvec_ms_jiffies) ||
+ (table->proc_handler == proc_doulongvec_minmax) ||
+ (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
+ if (!table->data)
+ err |= sysctl_err(path, table, "No data");
+ if (!table->maxlen)
+ err |= sysctl_err(path, table, "No maxlen");
+ else
+ err |= sysctl_check_table_array(path, table);
+ }
+ if (!table->proc_handler)
+ err |= sysctl_err(path, table, "No proc_handler");
+
+ if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
+ err |= sysctl_err(path, table, "bogus .mode 0%o",
+ table->mode);
+ }
+ return err;
+}
+
+static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
+ struct ctl_table_root *link_root)
+{
+ struct ctl_table *link_table, *entry, *link;
+ struct ctl_table_header *links;
+ struct ctl_node *node;
+ char *link_name;
+ int nr_entries, name_bytes;
+
+ name_bytes = 0;
+ nr_entries = 0;
+ for (entry = table; entry->procname; entry++) {
+ nr_entries++;
+ name_bytes += strlen(entry->procname) + 1;
+ }
+
+ links = kzalloc(sizeof(struct ctl_table_header) +
+ sizeof(struct ctl_node)*nr_entries +
+ sizeof(struct ctl_table)*(nr_entries + 1) +
+ name_bytes,
+ GFP_KERNEL);
+
+ if (!links)
+ return NULL;
+
+ node = (struct ctl_node *)(links + 1);
+ link_table = (struct ctl_table *)(node + nr_entries);
+ link_name = (char *)&link_table[nr_entries + 1];
+
+ for (link = link_table, entry = table; entry->procname; link++, entry++) {
+ int len = strlen(entry->procname) + 1;
+ memcpy(link_name, entry->procname, len);
+ link->procname = link_name;
+ link->mode = S_IFLNK|S_IRWXUGO;
+ link->data = link_root;
+ link_name += len;
+ }
+ init_header(links, dir->header.root, dir->header.set, node, link_table);
+ links->nreg = nr_entries;
+
+ return links;
+}
+
+static bool get_links(struct ctl_dir *dir,
+ struct ctl_table *table, struct ctl_table_root *link_root)
+{
+ struct ctl_table_header *head;
+ struct ctl_table *entry, *link;
+
+ /* Are there links available for every entry in table? */
+ for (entry = table; entry->procname; entry++) {
+ const char *procname = entry->procname;
+ link = find_entry(&head, dir, procname, strlen(procname));
+ if (!link)
+ return false;
+ if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
+ continue;
+ if (S_ISLNK(link->mode) && (link->data == link_root))
+ continue;
+ return false;
+ }
+
+ /* The checks passed. Increase the registration count on the links */
+ for (entry = table; entry->procname; entry++) {
+ const char *procname = entry->procname;
+ link = find_entry(&head, dir, procname, strlen(procname));
+ head->nreg++;
+ }
+ return true;
+}
+
+static int insert_links(struct ctl_table_header *head)
+{
+ struct ctl_table_set *root_set = &sysctl_table_root.default_set;
+ struct ctl_dir *core_parent = NULL;
+ struct ctl_table_header *links;
+ int err;
+
+ if (head->set == root_set)
+ return 0;
+
+ core_parent = xlate_dir(root_set, head->parent);
+ if (IS_ERR(core_parent))
+ return 0;
+
+ if (get_links(core_parent, head->ctl_table, head->root))
+ return 0;
+
+ core_parent->header.nreg++;
+ spin_unlock(&sysctl_lock);
+
+ links = new_links(core_parent, head->ctl_table, head->root);
+
+ spin_lock(&sysctl_lock);
+ err = -ENOMEM;
+ if (!links)
+ goto out;
+
+ err = 0;
+ if (get_links(core_parent, head->ctl_table, head->root)) {
+ kfree(links);
+ goto out;
+ }
+
+ err = insert_header(core_parent, links);
+ if (err)
+ kfree(links);
+out:
+ drop_sysctl_table(&core_parent->header);
+ return err;
+}
+
+/**
+ * __register_sysctl_table - register a leaf sysctl table
+ * @set: Sysctl tree to register on
+ * @path: The path to the directory the sysctl table is in.
+ * @table: the top-level table structure
+ *
+ * Register a sysctl table hierarchy. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * The members of the &struct ctl_table structure are used as follows:
+ *
+ * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
+ * enter a sysctl file
+ *
+ * data - a pointer to data for use by proc_handler
+ *
+ * maxlen - the maximum size in bytes of the data
+ *
+ * mode - the file permissions for the /proc/sys file
+ *
+ * child - must be %NULL.
+ *
+ * proc_handler - the text handler routine (described below)
+ *
+ * extra1, extra2 - extra pointers usable by the proc handler routines
+ *
+ * Leaf nodes in the sysctl tree will be represented by a single file
+ * under /proc; non-leaf nodes will be represented by directories.
+ *
+ * There must be a proc_handler routine for any terminal nodes.
+ * Several default handlers are available to cover common cases -
+ *
+ * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
+ * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
+ * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
+ *
+ * It is the handler's job to read the input buffer from user memory
+ * and process it. The handler should return 0 on success.
+ *
+ * This routine returns %NULL on a failure to register, and a pointer
+ * to the table header on success.
+ */
+struct ctl_table_header *__register_sysctl_table(
+ struct ctl_table_set *set,
+ const char *path, struct ctl_table *table)
+{
+ struct ctl_table_root *root = set->dir.header.root;
+ struct ctl_table_header *header;
+ const char *name, *nextname;
+ struct ctl_dir *dir;
+ struct ctl_table *entry;
+ struct ctl_node *node;
+ int nr_entries = 0;
+
+ for (entry = table; entry->procname; entry++)
+ nr_entries++;
+
+ header = kzalloc(sizeof(struct ctl_table_header) +
+ sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
+ if (!header)
+ return NULL;
+
+ node = (struct ctl_node *)(header + 1);
+ init_header(header, root, set, node, table);
+ if (sysctl_check_table(path, table))
+ goto fail;
+
+ spin_lock(&sysctl_lock);
+ dir = &set->dir;
+ /* Reference moved down the diretory tree get_subdir */
+ dir->header.nreg++;
+ spin_unlock(&sysctl_lock);
+
+ /* Find the directory for the ctl_table */
+ for (name = path; name; name = nextname) {
+ int namelen;
+ nextname = strchr(name, '/');
+ if (nextname) {
+ namelen = nextname - name;
+ nextname++;
+ } else {
+ namelen = strlen(name);
+ }
+ if (namelen == 0)
+ continue;
+
+ dir = get_subdir(dir, name, namelen);
+ if (IS_ERR(dir))
+ goto fail;
+ }
+
+ spin_lock(&sysctl_lock);
+ if (insert_header(dir, header))
+ goto fail_put_dir_locked;
+
+ drop_sysctl_table(&dir->header);
+ spin_unlock(&sysctl_lock);
+
+ return header;
+
+fail_put_dir_locked:
+ drop_sysctl_table(&dir->header);
+ spin_unlock(&sysctl_lock);
+fail:
+ kfree(header);
+ dump_stack();
+ return NULL;
+}
+
+/**
+ * register_sysctl - register a sysctl table
+ * @path: The path to the directory the sysctl table is in.
+ * @table: the table structure
+ *
+ * Register a sysctl table. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * See __register_sysctl_table for more details.
+ */
+struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
+{
+ return __register_sysctl_table(&sysctl_table_root.default_set,
+ path, table);
+}
+EXPORT_SYMBOL(register_sysctl);
+
+static char *append_path(const char *path, char *pos, const char *name)
+{
+ int namelen;
+ namelen = strlen(name);
+ if (((pos - path) + namelen + 2) >= PATH_MAX)
+ return NULL;
+ memcpy(pos, name, namelen);
+ pos[namelen] = '/';
+ pos[namelen + 1] = '\0';
+ pos += namelen + 1;
+ return pos;
+}
+
+static int count_subheaders(struct ctl_table *table)
+{
+ int has_files = 0;
+ int nr_subheaders = 0;
+ struct ctl_table *entry;
+
+ /* special case: no directory and empty directory */
+ if (!table || !table->procname)
+ return 1;
+
+ for (entry = table; entry->procname; entry++) {
+ if (entry->child)
+ nr_subheaders += count_subheaders(entry->child);
+ else
+ has_files = 1;
+ }
+ return nr_subheaders + has_files;
+}
+
+static int register_leaf_sysctl_tables(const char *path, char *pos,
+ struct ctl_table_header ***subheader, struct ctl_table_set *set,
+ struct ctl_table *table)
+{
+ struct ctl_table *ctl_table_arg = NULL;
+ struct ctl_table *entry, *files;
+ int nr_files = 0;
+ int nr_dirs = 0;
+ int err = -ENOMEM;
+
+ for (entry = table; entry->procname; entry++) {
+ if (entry->child)
+ nr_dirs++;
+ else
+ nr_files++;
+ }
+
+ files = table;
+ /* If there are mixed files and directories we need a new table */
+ if (nr_dirs && nr_files) {
+ struct ctl_table *new;
+ files = kcalloc(nr_files + 1, sizeof(struct ctl_table),
+ GFP_KERNEL);
+ if (!files)
+ goto out;
+
+ ctl_table_arg = files;
+ for (new = files, entry = table; entry->procname; entry++) {
+ if (entry->child)
+ continue;
+ *new = *entry;
+ new++;
+ }
+ }
+
+ /* Register everything except a directory full of subdirectories */
+ if (nr_files || !nr_dirs) {
+ struct ctl_table_header *header;
+ header = __register_sysctl_table(set, path, files);
+ if (!header) {
+ kfree(ctl_table_arg);
+ goto out;
+ }
+
+ /* Remember if we need to free the file table */
+ header->ctl_table_arg = ctl_table_arg;
+ **subheader = header;
+ (*subheader)++;
+ }
+
+ /* Recurse into the subdirectories. */
+ for (entry = table; entry->procname; entry++) {
+ char *child_pos;
+
+ if (!entry->child)
+ continue;
+
+ err = -ENAMETOOLONG;
+ child_pos = append_path(path, pos, entry->procname);
+ if (!child_pos)
+ goto out;
+
+ err = register_leaf_sysctl_tables(path, child_pos, subheader,
+ set, entry->child);
+ pos[0] = '\0';
+ if (err)
+ goto out;
+ }
+ err = 0;
+out:
+ /* On failure our caller will unregister all registered subheaders */
+ return err;
+}
+
+/**
+ * __register_sysctl_paths - register a sysctl table hierarchy
+ * @set: Sysctl tree to register on
+ * @path: The path to the directory the sysctl table is in.
+ * @table: the top-level table structure
+ *
+ * Register a sysctl table hierarchy. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * See __register_sysctl_table for more details.
+ */
+struct ctl_table_header *__register_sysctl_paths(
+ struct ctl_table_set *set,
+ const struct ctl_path *path, struct ctl_table *table)
+{
+ struct ctl_table *ctl_table_arg = table;
+ int nr_subheaders = count_subheaders(table);
+ struct ctl_table_header *header = NULL, **subheaders, **subheader;
+ const struct ctl_path *component;
+ char *new_path, *pos;
+
+ pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!new_path)
+ return NULL;
+
+ pos[0] = '\0';
+ for (component = path; component->procname; component++) {
+ pos = append_path(new_path, pos, component->procname);
+ if (!pos)
+ goto out;
+ }
+ while (table->procname && table->child && !table[1].procname) {
+ pos = append_path(new_path, pos, table->procname);
+ if (!pos)
+ goto out;
+ table = table->child;
+ }
+ if (nr_subheaders == 1) {
+ header = __register_sysctl_table(set, new_path, table);
+ if (header)
+ header->ctl_table_arg = ctl_table_arg;
+ } else {
+ header = kzalloc(sizeof(*header) +
+ sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
+ if (!header)
+ goto out;
+
+ subheaders = (struct ctl_table_header **) (header + 1);
+ subheader = subheaders;
+ header->ctl_table_arg = ctl_table_arg;
+
+ if (register_leaf_sysctl_tables(new_path, pos, &subheader,
+ set, table))
+ goto err_register_leaves;
+ }
+
+out:
+ kfree(new_path);
+ return header;
+
+err_register_leaves:
+ while (subheader > subheaders) {
+ struct ctl_table_header *subh = *(--subheader);
+ struct ctl_table *table = subh->ctl_table_arg;
+ unregister_sysctl_table(subh);
+ kfree(table);
+ }
+ kfree(header);
+ header = NULL;
+ goto out;
+}
+
+/**
+ * register_sysctl_table_path - register a sysctl table hierarchy
+ * @path: The path to the directory the sysctl table is in.
+ * @table: the top-level table structure
+ *
+ * Register a sysctl table hierarchy. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * See __register_sysctl_paths for more details.
+ */
+struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
+ struct ctl_table *table)
+{
+ return __register_sysctl_paths(&sysctl_table_root.default_set,
+ path, table);
+}
+EXPORT_SYMBOL(register_sysctl_paths);
+
+/**
+ * register_sysctl_table - register a sysctl table hierarchy
+ * @table: the top-level table structure
+ *
+ * Register a sysctl table hierarchy. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * See register_sysctl_paths for more details.
+ */
+struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
+{
+ static const struct ctl_path null_path[] = { {} };
+
+ return register_sysctl_paths(null_path, table);
+}
+EXPORT_SYMBOL(register_sysctl_table);
+
+static void put_links(struct ctl_table_header *header)
+{
+ struct ctl_table_set *root_set = &sysctl_table_root.default_set;
+ struct ctl_table_root *root = header->root;
+ struct ctl_dir *parent = header->parent;
+ struct ctl_dir *core_parent;
+ struct ctl_table *entry;
+
+ if (header->set == root_set)
+ return;
+
+ core_parent = xlate_dir(root_set, parent);
+ if (IS_ERR(core_parent))
+ return;
+
+ for (entry = header->ctl_table; entry->procname; entry++) {
+ struct ctl_table_header *link_head;
+ struct ctl_table *link;
+ const char *name = entry->procname;
+
+ link = find_entry(&link_head, core_parent, name, strlen(name));
+ if (link &&
+ ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
+ (S_ISLNK(link->mode) && (link->data == root)))) {
+ drop_sysctl_table(link_head);
+ }
+ else {
+ pr_err("sysctl link missing during unregister: ");
+ sysctl_print_dir(parent);
+ pr_cont("/%s\n", name);
+ }
+ }
+}
+
+static void drop_sysctl_table(struct ctl_table_header *header)
+{
+ struct ctl_dir *parent = header->parent;
+
+ if (--header->nreg)
+ return;
+
+ put_links(header);
+ start_unregistering(header);
+ if (!--header->count)
+ kfree_rcu(header, rcu);
+
+ if (parent)
+ drop_sysctl_table(&parent->header);
+}
+
+/**
+ * unregister_sysctl_table - unregister a sysctl table hierarchy
+ * @header: the header returned from register_sysctl_table
+ *
+ * Unregisters the sysctl table and all children. proc entries may not
+ * actually be removed until they are no longer used by anyone.
+ */
+void unregister_sysctl_table(struct ctl_table_header * header)
+{
+ int nr_subheaders;
+ might_sleep();
+
+ if (header == NULL)
+ return;
+
+ nr_subheaders = count_subheaders(header->ctl_table_arg);
+ if (unlikely(nr_subheaders > 1)) {
+ struct ctl_table_header **subheaders;
+ int i;
+
+ subheaders = (struct ctl_table_header **)(header + 1);
+ for (i = nr_subheaders -1; i >= 0; i--) {
+ struct ctl_table_header *subh = subheaders[i];
+ struct ctl_table *table = subh->ctl_table_arg;
+ unregister_sysctl_table(subh);
+ kfree(table);
+ }
+ kfree(header);
+ return;
+ }
+
+ spin_lock(&sysctl_lock);
+ drop_sysctl_table(header);
+ spin_unlock(&sysctl_lock);
+}
+EXPORT_SYMBOL(unregister_sysctl_table);
+
+void setup_sysctl_set(struct ctl_table_set *set,
+ struct ctl_table_root *root,
+ int (*is_seen)(struct ctl_table_set *))
+{
+ memset(set, 0, sizeof(*set));
+ set->is_seen = is_seen;
+ init_header(&set->dir.header, root, set, NULL, root_table);
+}
+
+void retire_sysctl_set(struct ctl_table_set *set)
+{
+ WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
+}
+
+int __init proc_sys_init(void)
+{
+ struct proc_dir_entry *proc_sys_root;
+
+ proc_sys_root = proc_mkdir("sys", NULL);
+ proc_sys_root->proc_iops = &proc_sys_dir_operations;
+ proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
+ proc_sys_root->nlink = 0;
+
+ return sysctl_init();
+}