diff options
Diffstat (limited to 'fs/proc/proc_sysctl.c')
| -rw-r--r-- | fs/proc/proc_sysctl.c | 1951 |
1 files changed, 1951 insertions, 0 deletions
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c new file mode 100644 index 000000000..4a4c04a3b --- /dev/null +++ b/fs/proc/proc_sysctl.c @@ -0,0 +1,1951 @@ +// 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/uio.h> +#include <linux/module.h> +#include <linux/bpf-cgroup.h> +#include <linux/mount.h> +#include <linux/kmemleak.h> +#include "internal.h" + +#define list_for_each_table_entry(entry, table) \ + for ((entry) = (table); (entry)->procname; (entry)++) + +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[] = { + { } +}; + +/** + * register_sysctl_mount_point() - registers a sysctl mount point + * @path: path for the mount point + * + * Used to create a permanently empty directory to serve as mount point. + * There are some subtle but important permission checks this allows in the + * case of unprivileged mounts. + */ +struct ctl_table_header *register_sysctl_mount_point(const char *path) +{ + return register_sysctl(path, sysctl_mount_point); +} +EXPORT_SYMBOL(register_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 cmp; + + cmp = memcmp(name1, name2, min(len1, len2)); + 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; + + list_for_each_table_entry(entry, table) { + node->header = head; + node++; + } + } +} + +static void erase_header(struct ctl_table_header *head) +{ + struct ctl_table *entry; + + list_for_each_table_entry(entry, head->ctl_table) + 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; + list_for_each_table_entry(entry, header->ctl_table) { + 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_invalidate_dcache(struct ctl_table_header *head) +{ + proc_invalidate_siblings_dcache(&head->inodes, &sysctl_lock); +} + +/* 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); + } + /* + * Invalidate dentries for unregistered sysctls: namespaced sysctls + * can have duplicate names and contaminate dcache very badly. + */ + proc_sys_invalidate_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->sibling_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); + else { + inode->i_uid = GLOBAL_ROOT_UID; + inode->i_gid = GLOBAL_ROOT_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)->sibling_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 kiocb *iocb, struct iov_iter *iter, + int write) +{ + struct inode *inode = file_inode(iocb->ki_filp); + struct ctl_table_header *head = grab_header(inode); + struct ctl_table *table = PROC_I(inode)->sysctl_entry; + size_t count = iov_iter_count(iter); + char *kbuf; + ssize_t error; + + 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; + + /* don't even try if the size is too large */ + error = -ENOMEM; + if (count >= KMALLOC_MAX_SIZE) + goto out; + kbuf = kvzalloc(count + 1, GFP_KERNEL); + if (!kbuf) + goto out; + + if (write) { + error = -EFAULT; + if (!copy_from_iter_full(kbuf, count, iter)) + goto out_free_buf; + kbuf[count] = '\0'; + } + + error = BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, &kbuf, &count, + &iocb->ki_pos); + if (error) + goto out_free_buf; + + /* careful: calling conventions are nasty here */ + error = table->proc_handler(table, write, kbuf, &count, &iocb->ki_pos); + if (error) + goto out_free_buf; + + if (!write) { + error = -EFAULT; + if (copy_to_iter(kbuf, count, iter) < count) + goto out_free_buf; + } + + error = count; +out_free_buf: + kvfree(kbuf); +out: + sysctl_head_finish(head); + + return error; +} + +static ssize_t proc_sys_read(struct kiocb *iocb, struct iov_iter *iter) +{ + return proc_sys_call_handler(iocb, iter, 0); +} + +static ssize_t proc_sys_write(struct kiocb *iocb, struct iov_iter *iter) +{ + return proc_sys_call_handler(iocb, iter, 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 user_namespace *mnt_userns, + 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 user_namespace *mnt_userns, + 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(&init_user_ns, dentry, attr); + if (error) + return error; + + setattr_copy(&init_user_ns, inode, attr); + mark_inode_dirty(inode); + return 0; +} + +static int proc_sys_getattr(struct user_namespace *mnt_userns, + 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(&init_user_ns, 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_iter = proc_sys_read, + .write_iter = proc_sys_write, + .splice_read = generic_file_splice_read, + .splice_write = iter_file_splice_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); + 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; + + 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"); + } + + if (table->proc_handler == proc_dou8vec_minmax) { + if (table->maxlen != sizeof(u8)) + err |= sysctl_err(path, table, "array not allowed"); + } + + return err; +} + +static int sysctl_check_table(const char *path, struct ctl_table *table) +{ + struct ctl_table *entry; + int err = 0; + list_for_each_table_entry(entry, table) { + if (entry->child) + err |= sysctl_err(path, entry, "Not a file"); + + if ((entry->proc_handler == proc_dostring) || + (entry->proc_handler == proc_dointvec) || + (entry->proc_handler == proc_douintvec) || + (entry->proc_handler == proc_douintvec_minmax) || + (entry->proc_handler == proc_dointvec_minmax) || + (entry->proc_handler == proc_dou8vec_minmax) || + (entry->proc_handler == proc_dointvec_jiffies) || + (entry->proc_handler == proc_dointvec_userhz_jiffies) || + (entry->proc_handler == proc_dointvec_ms_jiffies) || + (entry->proc_handler == proc_doulongvec_minmax) || + (entry->proc_handler == proc_doulongvec_ms_jiffies_minmax)) { + if (!entry->data) + err |= sysctl_err(path, entry, "No data"); + if (!entry->maxlen) + err |= sysctl_err(path, entry, "No maxlen"); + else + err |= sysctl_check_table_array(path, entry); + } + if (!entry->proc_handler) + err |= sysctl_err(path, entry, "No proc_handler"); + + if ((entry->mode & (S_IRUGO|S_IWUGO)) != entry->mode) + err |= sysctl_err(path, entry, "bogus .mode 0%o", + entry->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; + list_for_each_table_entry(entry, table) { + 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]; + link = link_table; + + list_for_each_table_entry(entry, table) { + 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; + link++; + } + 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? */ + list_for_each_table_entry(entry, table) { + 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 */ + list_for_each_table_entry(entry, table) { + 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; + 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 without any child. This table + * should not be free'd after registration. So it should not be + * used on stack. It can either be a global or dynamically allocated + * by the caller and free'd later after sysctl unregistration. + * + * 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 + * XXX: we should eventually modify these to use long min / max [0] + * [0] https://lkml.kernel.org/87zgpte9o4.fsf@email.froward.int.ebiederm.org + * + * Leaf nodes in the sysctl tree will be represented by a single file + * under /proc; non-leaf nodes (where child is not NULL) are not allowed, + * sysctl_check_table() verifies this. + * + * 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; + + list_for_each_table_entry(entry, table) + nr_entries++; + + header = kzalloc(sizeof(struct ctl_table_header) + + sizeof(struct ctl_node)*nr_entries, GFP_KERNEL_ACCOUNT); + 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 directory 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; + + /* + * namelen ensures if name is "foo/bar/yay" only foo is + * registered first. We traverse as if using mkdir -p and + * return a ctl_dir for the last directory entry. + */ + 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. If the path + * doesn't exist we will create it for you. + * @table: the table structure. The calller must ensure the life of the @table + * will be kept during the lifetime use of the syctl. It must not be freed + * until unregister_sysctl_table() is called with the given returned table + * with this registration. If your code is non modular then you don't need + * to call unregister_sysctl_table() and can instead use something like + * register_sysctl_init() which does not care for the result of the syctl + * registration. + * + * 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); + +/** + * __register_sysctl_init() - register sysctl table to path + * @path: path name for sysctl base. If that path doesn't exist we will create + * it for you. + * @table: This is the sysctl table that needs to be registered to the path. + * The caller must ensure the life of the @table will be kept during the + * lifetime use of the sysctl. + * @table_name: The name of sysctl table, only used for log printing when + * registration fails + * + * The sysctl interface is used by userspace to query or modify at runtime + * a predefined value set on a variable. These variables however have default + * values pre-set. Code which depends on these variables will always work even + * if register_sysctl() fails. If register_sysctl() fails you'd just loose the + * ability to query or modify the sysctls dynamically at run time. Chances of + * register_sysctl() failing on init are extremely low, and so for both reasons + * this function does not return any error as it is used by initialization code. + * + * Context: if your base directory does not exist it will be created for you. + */ +void __init __register_sysctl_init(const char *path, struct ctl_table *table, + const char *table_name) +{ + struct ctl_table_header *hdr = register_sysctl(path, table); + + if (unlikely(!hdr)) { + pr_err("failed when register_sysctl %s to %s\n", table_name, path); + return; + } + kmemleak_not_leak(hdr); +} + +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; + + list_for_each_table_entry(entry, table) { + 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; + + list_for_each_table_entry(entry, table) { + 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; + new = files; + + list_for_each_table_entry(entry, table) { + 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. */ + list_for_each_table_entry(entry, table) { + 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. + * We are slowly deprecating this call so avoid its use. + * + * 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_paths - 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. + * We are slowly deprecating this caller so avoid future uses of it. + * + * 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); + +int __register_sysctl_base(struct ctl_table *base_table) +{ + struct ctl_table_header *hdr; + + hdr = register_sysctl_table(base_table); + kmemleak_not_leak(hdr); + return 0; +} + +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; + + list_for_each_table_entry(entry, header->ctl_table) { + 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; + + if (parent) { + 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_dir_ops = &proc_sys_dir_file_operations; + proc_sys_root->nlink = 0; + + return sysctl_init_bases(); +} + +struct sysctl_alias { + const char *kernel_param; + const char *sysctl_param; +}; + +/* + * Historically some settings had both sysctl and a command line parameter. + * With the generic sysctl. parameter support, we can handle them at a single + * place and only keep the historical name for compatibility. This is not meant + * to add brand new aliases. When adding existing aliases, consider whether + * the possibly different moment of changing the value (e.g. from early_param + * to the moment do_sysctl_args() is called) is an issue for the specific + * parameter. + */ +static const struct sysctl_alias sysctl_aliases[] = { + {"hardlockup_all_cpu_backtrace", "kernel.hardlockup_all_cpu_backtrace" }, + {"hung_task_panic", "kernel.hung_task_panic" }, + {"numa_zonelist_order", "vm.numa_zonelist_order" }, + {"softlockup_all_cpu_backtrace", "kernel.softlockup_all_cpu_backtrace" }, + { } +}; + +static const char *sysctl_find_alias(char *param) +{ + const struct sysctl_alias *alias; + + for (alias = &sysctl_aliases[0]; alias->kernel_param != NULL; alias++) { + if (strcmp(alias->kernel_param, param) == 0) + return alias->sysctl_param; + } + + return NULL; +} + +bool sysctl_is_alias(char *param) +{ + const char *alias = sysctl_find_alias(param); + + return alias != NULL; +} + +/* Set sysctl value passed on kernel command line. */ +static int process_sysctl_arg(char *param, char *val, + const char *unused, void *arg) +{ + char *path; + struct vfsmount **proc_mnt = arg; + struct file_system_type *proc_fs_type; + struct file *file; + int len; + int err; + loff_t pos = 0; + ssize_t wret; + + if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) { + param += sizeof("sysctl") - 1; + + if (param[0] != '/' && param[0] != '.') + return 0; + + param++; + } else { + param = (char *) sysctl_find_alias(param); + if (!param) + return 0; + } + + if (!val) + return -EINVAL; + len = strlen(val); + if (len == 0) + return -EINVAL; + + /* + * To set sysctl options, we use a temporary mount of proc, look up the + * respective sys/ file and write to it. To avoid mounting it when no + * options were given, we mount it only when the first sysctl option is + * found. Why not a persistent mount? There are problems with a + * persistent mount of proc in that it forces userspace not to use any + * proc mount options. + */ + if (!*proc_mnt) { + proc_fs_type = get_fs_type("proc"); + if (!proc_fs_type) { + pr_err("Failed to find procfs to set sysctl from command line\n"); + return 0; + } + *proc_mnt = kern_mount(proc_fs_type); + put_filesystem(proc_fs_type); + if (IS_ERR(*proc_mnt)) { + pr_err("Failed to mount procfs to set sysctl from command line\n"); + return 0; + } + } + + path = kasprintf(GFP_KERNEL, "sys/%s", param); + if (!path) + panic("%s: Failed to allocate path for %s\n", __func__, param); + strreplace(path, '.', '/'); + + file = file_open_root_mnt(*proc_mnt, path, O_WRONLY, 0); + if (IS_ERR(file)) { + err = PTR_ERR(file); + if (err == -ENOENT) + pr_err("Failed to set sysctl parameter '%s=%s': parameter not found\n", + param, val); + else if (err == -EACCES) + pr_err("Failed to set sysctl parameter '%s=%s': permission denied (read-only?)\n", + param, val); + else + pr_err("Error %pe opening proc file to set sysctl parameter '%s=%s'\n", + file, param, val); + goto out; + } + wret = kernel_write(file, val, len, &pos); + if (wret < 0) { + err = wret; + if (err == -EINVAL) + pr_err("Failed to set sysctl parameter '%s=%s': invalid value\n", + param, val); + else + pr_err("Error %pe writing to proc file to set sysctl parameter '%s=%s'\n", + ERR_PTR(err), param, val); + } else if (wret != len) { + pr_err("Wrote only %zd bytes of %d writing to proc file %s to set sysctl parameter '%s=%s\n", + wret, len, path, param, val); + } + + err = filp_close(file, NULL); + if (err) + pr_err("Error %pe closing proc file to set sysctl parameter '%s=%s\n", + ERR_PTR(err), param, val); +out: + kfree(path); + return 0; +} + +void do_sysctl_args(void) +{ + char *command_line; + struct vfsmount *proc_mnt = NULL; + + command_line = kstrdup(saved_command_line, GFP_KERNEL); + if (!command_line) + panic("%s: Failed to allocate copy of command line\n", __func__); + + parse_args("Setting sysctl args", command_line, + NULL, 0, -1, -1, &proc_mnt, process_sysctl_arg); + + if (proc_mnt) + kern_unmount(proc_mnt); + + kfree(command_line); +} |