/* * /proc/sys support */ #include <linux/init.h> #include <linux/sysctl.h> #include <linux/poll.h> #include <linux/proc_fs.h> #include <linux/security.h> #include <linux/namei.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; 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; static struct ctl_dir sysctl_root_dir = { .header = { {{.count = 1, .nreg = 1, .ctl_table = root_table, .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),}}, .root = &sysctl_table_root, .set = &sysctl_table_root.default_set, }, }; static struct ctl_table_root sysctl_table_root = { .root_list = LIST_HEAD_INIT(sysctl_table_root.root_list), .default_set.list = LIST_HEAD_INIT(sysctl_root_dir.header.ctl_entry), .default_set.root = &sysctl_table_root, }; static DEFINE_SPINLOCK(sysctl_lock); static void drop_sysctl_table(struct ctl_table_header *header); static void sysctl_print_dir(struct ctl_dir *dir) { if (dir->header.parent) sysctl_print_dir(dir->header.parent); printk(KERN_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; } static struct ctl_table *find_entry(struct ctl_table_header **phead, struct ctl_table_set *set, struct ctl_dir *dir, const char *name, int namelen) { struct ctl_table_header *head; struct ctl_table *entry; list_for_each_entry(head, &set->list, ctl_entry) { if (head->unregistering) continue; if (head->parent != dir) continue; for (entry = head->ctl_table; entry->procname; entry++) { const char *procname = entry->procname; if (namecmp(procname, strlen(procname), name, namelen) == 0) { *phead = head; return entry; } } } return NULL; } static void init_header(struct ctl_table_header *head, struct ctl_table_root *root, struct ctl_table_set *set, struct ctl_table *table) { head->ctl_table = table; head->ctl_table_arg = table; INIT_LIST_HEAD(&head->ctl_entry); head->used = 0; head->count = 1; head->nreg = 1; head->unregistering = NULL; head->root = root; head->set = set; head->parent = NULL; } static void erase_header(struct ctl_table_header *head) { list_del_init(&head->ctl_entry); } static void insert_header(struct ctl_dir *dir, struct ctl_table_header *header) { header->parent = dir; header->parent->header.nreg++; list_add_tail(&header->ctl_entry, &header->set->list); } /* 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); } /* 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); spin_lock(&sysctl_lock); } else { /* anything non-NULL; we'll never dereference it */ p->unregistering = ERR_PTR(-EINVAL); } /* * do not remove from the list until nobody holds it; walking the * list in do_sysctl() relies on that. */ erase_header(p); } static void sysctl_head_get(struct ctl_table_header *head) { spin_lock(&sysctl_lock); head->count++; spin_unlock(&sysctl_lock); } void sysctl_head_put(struct ctl_table_header *head) { spin_lock(&sysctl_lock); if (!--head->count) kfree_rcu(head, rcu); spin_unlock(&sysctl_lock); } static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head) { if (!head) BUG(); 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 nsproxy *namespaces) { struct ctl_table_set *set = &root->default_set; if (root->lookup) set = root->lookup(root, namespaces); return set; } static struct list_head * lookup_header_list(struct ctl_table_root *root, struct nsproxy *namespaces) { struct ctl_table_set *set = lookup_header_set(root, namespaces); return &set->list; } 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; struct ctl_table_root *root; struct ctl_table_set *set; spin_lock(&sysctl_lock); root = &sysctl_table_root; do { set = lookup_header_set(root, current->nsproxy); entry = find_entry(&head, set, dir, name, namelen); if (entry && use_table(head)) *phead = head; else entry = NULL; root = list_entry(root->root_list.next, struct ctl_table_root, root_list); } while (!entry && root != &sysctl_table_root); spin_unlock(&sysctl_lock); return entry; } static struct ctl_table_header *next_usable_entry(struct ctl_dir *dir, struct ctl_table_root *root, struct list_head *tmp) { struct nsproxy *namespaces = current->nsproxy; struct list_head *header_list; struct ctl_table_header *head; goto next; for (;;) { head = list_entry(tmp, struct ctl_table_header, ctl_entry); root = head->root; if (head->parent != dir || !head->ctl_table->procname || !use_table(head)) goto next; return head; next: tmp = tmp->next; header_list = lookup_header_list(root, namespaces); if (tmp != header_list) continue; do { root = list_entry(root->root_list.next, struct ctl_table_root, root_list); if (root == &sysctl_table_root) goto out; header_list = lookup_header_list(root, namespaces); } while (list_empty(header_list)); tmp = header_list->next; } out: return NULL; } static void first_entry(struct ctl_dir *dir, struct ctl_table_header **phead, struct ctl_table **pentry) { struct ctl_table_header *head; struct ctl_table *entry = NULL; spin_lock(&sysctl_lock); head = next_usable_entry(dir, &sysctl_table_root, &sysctl_table_root.default_set.list); spin_unlock(&sysctl_lock); if (head) entry = head->ctl_table; *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; entry++; if (!entry->procname) { spin_lock(&sysctl_lock); unuse_table(head); head = next_usable_entry(head->parent, head->root, &head->ctl_entry); spin_unlock(&sysctl_lock); if (head) entry = head->ctl_table; } *phead = head; *pentry = entry; } void register_sysctl_root(struct ctl_table_root *root) { spin_lock(&sysctl_lock); list_add_tail(&root->root_list, &sysctl_table_root.root_list); spin_unlock(&sysctl_lock); } /* * 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 (!current_euid()) mode >>= 6; else if (in_egroup_p(0)) mode >>= 3; if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0) return 0; return -EACCES; } static int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op) { int mode; if (root->permissions) mode = root->permissions(root, current->nsproxy, 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 inode *inode; struct proc_inode *ei; inode = new_inode(sb); if (!inode) goto out; inode->i_ino = get_next_ino(); sysctl_head_get(head); ei = PROC_I(inode); ei->sysctl = head; ei->sysctl_entry = table; inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 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; } out: return inode; } static struct ctl_table_header *grab_header(struct inode *inode) { struct ctl_table_header *head = PROC_I(inode)->sysctl; if (!head) head = &sysctl_root_dir.header; return sysctl_head_grab(head); } static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) { struct ctl_table_header *head = grab_header(dir); struct ctl_table_header *h = NULL; struct qstr *name = &dentry->d_name; struct ctl_table *p; struct inode *inode; struct dentry *err = ERR_PTR(-ENOENT); struct ctl_dir *ctl_dir; 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; err = ERR_PTR(-ENOMEM); inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); if (h) sysctl_head_finish(h); if (!inode) goto out; err = NULL; d_set_d_op(dentry, &proc_sys_dentry_operations); d_add(dentry, inode); out: 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 = filp->f_path.dentry->d_inode; 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->root, 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 *table = PROC_I(inode)->sysctl_entry; if (table->poll) filp->private_data = proc_sys_poll_event(table->poll); return 0; } static unsigned int proc_sys_poll(struct file *filp, poll_table *wait) { struct inode *inode = filp->f_path.dentry->d_inode; struct ctl_table *table = PROC_I(inode)->sysctl_entry; unsigned long event = (unsigned long)filp->private_data; unsigned int ret = DEFAULT_POLLMASK; if (!table->proc_handler) goto out; if (!table->poll) goto out; poll_wait(filp, &table->poll->wait, wait); if (event != atomic_read(&table->poll->event)) { filp->private_data = proc_sys_poll_event(table->poll); ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI; } out: return ret; } static int proc_sys_fill_cache(struct file *filp, void *dirent, filldir_t filldir, struct ctl_table_header *head, struct ctl_table *table) { struct dentry *child, *dir = filp->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(qname.name, qname.len); child = d_lookup(dir, &qname); if (!child) { child = d_alloc(dir, &qname); if (child) { inode = proc_sys_make_inode(dir->d_sb, head, table); if (!inode) { dput(child); return -ENOMEM; } else { d_set_d_op(child, &proc_sys_dentry_operations); d_add(child, inode); } } else { return -ENOMEM; } } inode = child->d_inode; ino = inode->i_ino; type = inode->i_mode >> 12; dput(child); return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type); } static int scan(struct ctl_table_header *head, ctl_table *table, unsigned long *pos, struct file *file, void *dirent, filldir_t filldir) { int res; if ((*pos)++ < file->f_pos) return 0; res = proc_sys_fill_cache(file, dirent, filldir, head, table); if (res == 0) file->f_pos = *pos; return res; } static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir) { struct dentry *dentry = filp->f_path.dentry; struct inode *inode = dentry->d_inode; struct ctl_table_header *head = grab_header(inode); struct ctl_table_header *h = NULL; struct ctl_table *entry; struct ctl_dir *ctl_dir; unsigned long pos; int ret = -EINVAL; if (IS_ERR(head)) return PTR_ERR(head); ctl_dir = container_of(head, struct ctl_dir, header); ret = 0; /* Avoid a switch here: arm builds fail with missing __cmpdi2 */ if (filp->f_pos == 0) { if (filldir(dirent, ".", 1, filp->f_pos, inode->i_ino, DT_DIR) < 0) goto out; filp->f_pos++; } if (filp->f_pos == 1) { if (filldir(dirent, "..", 2, filp->f_pos, parent_ino(dentry), DT_DIR) < 0) goto out; filp->f_pos++; } pos = 2; for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) { ret = scan(h, entry, &pos, filp, dirent, filldir); if (ret) { sysctl_head_finish(h); break; } } ret = 1; out: sysctl_head_finish(head); return ret; } 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->root, 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 = dentry->d_inode; int error; if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) return -EPERM; error = inode_change_ok(inode, attr); if (error) return error; if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size != i_size_read(inode)) { error = vmtruncate(inode, attr->ia_size); if (error) return error; } setattr_copy(inode, attr); mark_inode_dirty(inode); return 0; } static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) { struct inode *inode = dentry->d_inode; 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, .readdir = 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, struct nameidata *nd) { if (nd->flags & LOOKUP_RCU) return -ECHILD; return !PROC_I(dentry->d_inode)->sysctl->unregistering; } static int proc_sys_delete(const struct dentry *dentry) { return !!PROC_I(dentry->d_inode)->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 *parent, const struct inode *pinode, const struct dentry *dentry, const struct inode *inode, unsigned int len, const char *str, const struct qstr *name) { struct ctl_table_header *head; /* Although proc doesn't have negative dentries, rcu-walk means * that inode here can be NULL */ /* AV: can it, indeed? */ 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_table_set *set, struct ctl_dir *dir, const char *name, int namelen) { struct ctl_table_header *head; struct ctl_table *entry; entry = find_entry(&head, set, dir, name, namelen); if (!entry) return ERR_PTR(-ENOENT); if (S_ISDIR(entry->mode)) return container_of(head, struct ctl_dir, header); return ERR_PTR(-ENOTDIR); } static struct ctl_dir *new_dir(struct ctl_table_set *set, const char *name, int namelen) { struct ctl_table *table; struct ctl_dir *new; char *new_name; new = kzalloc(sizeof(*new) + sizeof(struct ctl_table)*2 + namelen + 1, GFP_KERNEL); if (!new) return NULL; table = (struct ctl_table *)(new + 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->root, set, table); return new; } static struct ctl_dir *get_subdir(struct ctl_table_set *set, struct ctl_dir *dir, const char *name, int namelen) { struct ctl_dir *subdir, *new = NULL; spin_lock(&sysctl_lock); subdir = find_subdir(dir->header.set, dir, name, namelen); if (!IS_ERR(subdir)) goto found; if ((PTR_ERR(subdir) == -ENOENT) && set != dir->header.set) subdir = find_subdir(set, 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; subdir = find_subdir(set, dir, name, namelen); if (!IS_ERR(subdir)) goto found; if (PTR_ERR(subdir) != -ENOENT) goto failed; insert_header(dir, &new->header); subdir = new; found: subdir->header.nreg++; failed: if (unlikely(IS_ERR(subdir))) { printk(KERN_ERR "sysctl could not get directory: "); sysctl_print_dir(dir); printk(KERN_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 int sysctl_check_table_dups(const char *path, struct ctl_table *old, struct ctl_table *table) { struct ctl_table *entry, *test; int error = 0; for (entry = old; entry->procname; entry++) { for (test = table; test->procname; test++) { if (strcmp(entry->procname, test->procname) == 0) { printk(KERN_ERR "sysctl duplicate entry: %s/%s\n", path, test->procname); error = -EEXIST; } } } return error; } static int sysctl_check_dups(struct nsproxy *namespaces, struct ctl_dir *dir, const char *path, struct ctl_table *table) { struct ctl_table_root *root; struct ctl_table_set *set; struct ctl_table_header *head; int error = 0; root = &sysctl_table_root; do { set = lookup_header_set(root, namespaces); list_for_each_entry(head, &set->list, ctl_entry) { if (head->unregistering) continue; if (head->parent != dir) continue; error = sysctl_check_table_dups(path, head->ctl_table, table); } root = list_entry(root->root_list.next, struct ctl_table_root, root_list); } while (root != &sysctl_table_root); return error; } 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; printk(KERN_ERR "sysctl table check failed: %s/%s %pV\n", path, table->procname, &vaf); va_end(args); return -EINVAL; } 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_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"); } 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; } /** * __register_sysctl_table - register a leaf sysctl table * @root: List of sysctl headers to register on * @namespaces: Data to compute which lists of sysctl entries are visible * @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_root *root, struct nsproxy *namespaces, const char *path, struct ctl_table *table) { struct ctl_table_header *header; const char *name, *nextname; struct ctl_table_set *set; struct ctl_dir *dir; header = kzalloc(sizeof(struct ctl_table_header), GFP_KERNEL); if (!header) return NULL; init_header(header, root, NULL, table); if (sysctl_check_table(path, table)) goto fail; spin_lock(&sysctl_lock); header->set = set = lookup_header_set(root, namespaces); dir = &sysctl_root_dir; 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(set, dir, name, namelen); if (IS_ERR(dir)) goto fail; } spin_lock(&sysctl_lock); if (sysctl_check_dups(namespaces, dir, path, table)) goto fail_put_dir_locked; insert_header(dir, header); 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; } 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_root *root, struct nsproxy *namespaces, 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 = kzalloc(sizeof(struct ctl_table) * (nr_files + 1), 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(root, namespaces, 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, root, namespaces, 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 * @root: List of sysctl headers to register on * @namespaces: Data to compute which lists of sysctl entries are visible * @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_root *root, struct nsproxy *namespaces, 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(root, namespaces, 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, root, namespaces, 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, current->nsproxy, 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 drop_sysctl_table(struct ctl_table_header *header) { struct ctl_dir *parent = header->parent; if (--header->nreg) return; 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 *p, struct ctl_table_root *root, int (*is_seen)(struct ctl_table_set *)) { INIT_LIST_HEAD(&p->list); p->root = root; p->is_seen = is_seen; } void retire_sysctl_set(struct ctl_table_set *set) { WARN_ON(!list_empty(&set->list)); } 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(); }