// SPDX-License-Identifier: GPL-2.0-only /* * fs/kernfs/inode.c - kernfs inode implementation * * Copyright (c) 2001-3 Patrick Mochel * Copyright (c) 2007 SUSE Linux Products GmbH * Copyright (c) 2007, 2013 Tejun Heo */ #include #include #include #include #include #include #include #include "kernfs-internal.h" static const struct address_space_operations kernfs_aops = { .readpage = simple_readpage, .write_begin = simple_write_begin, .write_end = simple_write_end, }; static const struct inode_operations kernfs_iops = { .permission = kernfs_iop_permission, .setattr = kernfs_iop_setattr, .getattr = kernfs_iop_getattr, .listxattr = kernfs_iop_listxattr, }; static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc) { static DEFINE_MUTEX(iattr_mutex); struct kernfs_iattrs *ret; mutex_lock(&iattr_mutex); if (kn->iattr || !alloc) goto out_unlock; kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL); if (!kn->iattr) goto out_unlock; /* assign default attributes */ kn->iattr->ia_uid = GLOBAL_ROOT_UID; kn->iattr->ia_gid = GLOBAL_ROOT_GID; ktime_get_real_ts64(&kn->iattr->ia_atime); kn->iattr->ia_mtime = kn->iattr->ia_atime; kn->iattr->ia_ctime = kn->iattr->ia_atime; simple_xattrs_init(&kn->iattr->xattrs); atomic_set(&kn->iattr->nr_user_xattrs, 0); atomic_set(&kn->iattr->user_xattr_size, 0); out_unlock: ret = kn->iattr; mutex_unlock(&iattr_mutex); return ret; } static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn) { return __kernfs_iattrs(kn, 1); } static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn) { return __kernfs_iattrs(kn, 0); } int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr) { struct kernfs_iattrs *attrs; unsigned int ia_valid = iattr->ia_valid; attrs = kernfs_iattrs(kn); if (!attrs) return -ENOMEM; if (ia_valid & ATTR_UID) attrs->ia_uid = iattr->ia_uid; if (ia_valid & ATTR_GID) attrs->ia_gid = iattr->ia_gid; if (ia_valid & ATTR_ATIME) attrs->ia_atime = iattr->ia_atime; if (ia_valid & ATTR_MTIME) attrs->ia_mtime = iattr->ia_mtime; if (ia_valid & ATTR_CTIME) attrs->ia_ctime = iattr->ia_ctime; if (ia_valid & ATTR_MODE) kn->mode = iattr->ia_mode; return 0; } /** * kernfs_setattr - set iattr on a node * @kn: target node * @iattr: iattr to set * * Returns 0 on success, -errno on failure. */ int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr) { int ret; mutex_lock(&kernfs_mutex); ret = __kernfs_setattr(kn, iattr); mutex_unlock(&kernfs_mutex); return ret; } int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr) { struct inode *inode = d_inode(dentry); struct kernfs_node *kn = inode->i_private; int error; if (!kn) return -EINVAL; mutex_lock(&kernfs_mutex); error = setattr_prepare(dentry, iattr); if (error) goto out; error = __kernfs_setattr(kn, iattr); if (error) goto out; /* this ignores size changes */ setattr_copy(inode, iattr); out: mutex_unlock(&kernfs_mutex); return error; } ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size) { struct kernfs_node *kn = kernfs_dentry_node(dentry); struct kernfs_iattrs *attrs; attrs = kernfs_iattrs(kn); if (!attrs) return -ENOMEM; return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size); } static inline void set_default_inode_attr(struct inode *inode, umode_t mode) { inode->i_mode = mode; inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); } static inline void set_inode_attr(struct inode *inode, struct kernfs_iattrs *attrs) { inode->i_uid = attrs->ia_uid; inode->i_gid = attrs->ia_gid; inode->i_atime = attrs->ia_atime; inode->i_mtime = attrs->ia_mtime; inode->i_ctime = attrs->ia_ctime; } static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode) { struct kernfs_iattrs *attrs = kn->iattr; inode->i_mode = kn->mode; if (attrs) /* * kernfs_node has non-default attributes get them from * persistent copy in kernfs_node. */ set_inode_attr(inode, attrs); if (kernfs_type(kn) == KERNFS_DIR) set_nlink(inode, kn->dir.subdirs + 2); } int kernfs_iop_getattr(const struct path *path, struct kstat *stat, u32 request_mask, unsigned int query_flags) { struct inode *inode = d_inode(path->dentry); struct kernfs_node *kn = inode->i_private; mutex_lock(&kernfs_mutex); kernfs_refresh_inode(kn, inode); mutex_unlock(&kernfs_mutex); generic_fillattr(inode, stat); return 0; } static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode) { kernfs_get(kn); inode->i_private = kn; inode->i_mapping->a_ops = &kernfs_aops; inode->i_op = &kernfs_iops; inode->i_generation = kernfs_gen(kn); set_default_inode_attr(inode, kn->mode); kernfs_refresh_inode(kn, inode); /* initialize inode according to type */ switch (kernfs_type(kn)) { case KERNFS_DIR: inode->i_op = &kernfs_dir_iops; inode->i_fop = &kernfs_dir_fops; if (kn->flags & KERNFS_EMPTY_DIR) make_empty_dir_inode(inode); break; case KERNFS_FILE: inode->i_size = kn->attr.size; inode->i_fop = &kernfs_file_fops; break; case KERNFS_LINK: inode->i_op = &kernfs_symlink_iops; break; default: BUG(); } unlock_new_inode(inode); } /** * kernfs_get_inode - get inode for kernfs_node * @sb: super block * @kn: kernfs_node to allocate inode for * * Get inode for @kn. If such inode doesn't exist, a new inode is * allocated and basics are initialized. New inode is returned * locked. * * LOCKING: * Kernel thread context (may sleep). * * RETURNS: * Pointer to allocated inode on success, NULL on failure. */ struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn) { struct inode *inode; inode = iget_locked(sb, kernfs_ino(kn)); if (inode && (inode->i_state & I_NEW)) kernfs_init_inode(kn, inode); return inode; } /* * The kernfs_node serves as both an inode and a directory entry for * kernfs. To prevent the kernfs inode numbers from being freed * prematurely we take a reference to kernfs_node from the kernfs inode. A * super_operations.evict_inode() implementation is needed to drop that * reference upon inode destruction. */ void kernfs_evict_inode(struct inode *inode) { struct kernfs_node *kn = inode->i_private; truncate_inode_pages_final(&inode->i_data); clear_inode(inode); kernfs_put(kn); } int kernfs_iop_permission(struct inode *inode, int mask) { struct kernfs_node *kn; if (mask & MAY_NOT_BLOCK) return -ECHILD; kn = inode->i_private; mutex_lock(&kernfs_mutex); kernfs_refresh_inode(kn, inode); mutex_unlock(&kernfs_mutex); return generic_permission(&init_user_ns, inode, mask); } int kernfs_xattr_get(struct kernfs_node *kn, const char *name, void *value, size_t size) { struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn); if (!attrs) return -ENODATA; return simple_xattr_get(&attrs->xattrs, name, value, size); } int kernfs_xattr_set(struct kernfs_node *kn, const char *name, const void *value, size_t size, int flags) { struct kernfs_iattrs *attrs = kernfs_iattrs(kn); if (!attrs) return -ENOMEM; return simple_xattr_set(&attrs->xattrs, name, value, size, flags, NULL); } static int kernfs_vfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, const char *suffix, void *value, size_t size) { const char *name = xattr_full_name(handler, suffix); struct kernfs_node *kn = inode->i_private; return kernfs_xattr_get(kn, name, value, size); } static int kernfs_vfs_xattr_set(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, const char *suffix, const void *value, size_t size, int flags) { const char *name = xattr_full_name(handler, suffix); struct kernfs_node *kn = inode->i_private; return kernfs_xattr_set(kn, name, value, size, flags); } static int kernfs_vfs_user_xattr_add(struct kernfs_node *kn, const char *full_name, struct simple_xattrs *xattrs, const void *value, size_t size, int flags) { atomic_t *sz = &kn->iattr->user_xattr_size; atomic_t *nr = &kn->iattr->nr_user_xattrs; ssize_t removed_size; int ret; if (atomic_inc_return(nr) > KERNFS_MAX_USER_XATTRS) { ret = -ENOSPC; goto dec_count_out; } if (atomic_add_return(size, sz) > KERNFS_USER_XATTR_SIZE_LIMIT) { ret = -ENOSPC; goto dec_size_out; } ret = simple_xattr_set(xattrs, full_name, value, size, flags, &removed_size); if (!ret && removed_size >= 0) size = removed_size; else if (!ret) return 0; dec_size_out: atomic_sub(size, sz); dec_count_out: atomic_dec(nr); return ret; } static int kernfs_vfs_user_xattr_rm(struct kernfs_node *kn, const char *full_name, struct simple_xattrs *xattrs, const void *value, size_t size, int flags) { atomic_t *sz = &kn->iattr->user_xattr_size; atomic_t *nr = &kn->iattr->nr_user_xattrs; ssize_t removed_size; int ret; ret = simple_xattr_set(xattrs, full_name, value, size, flags, &removed_size); if (removed_size >= 0) { atomic_sub(removed_size, sz); atomic_dec(nr); } return ret; } static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, const char *suffix, const void *value, size_t size, int flags) { const char *full_name = xattr_full_name(handler, suffix); struct kernfs_node *kn = inode->i_private; struct kernfs_iattrs *attrs; if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR)) return -EOPNOTSUPP; attrs = kernfs_iattrs(kn); if (!attrs) return -ENOMEM; if (value) return kernfs_vfs_user_xattr_add(kn, full_name, &attrs->xattrs, value, size, flags); else return kernfs_vfs_user_xattr_rm(kn, full_name, &attrs->xattrs, value, size, flags); } static const struct xattr_handler kernfs_trusted_xattr_handler = { .prefix = XATTR_TRUSTED_PREFIX, .get = kernfs_vfs_xattr_get, .set = kernfs_vfs_xattr_set, }; static const struct xattr_handler kernfs_security_xattr_handler = { .prefix = XATTR_SECURITY_PREFIX, .get = kernfs_vfs_xattr_get, .set = kernfs_vfs_xattr_set, }; static const struct xattr_handler kernfs_user_xattr_handler = { .prefix = XATTR_USER_PREFIX, .get = kernfs_vfs_xattr_get, .set = kernfs_vfs_user_xattr_set, }; const struct xattr_handler *kernfs_xattr_handlers[] = { &kernfs_trusted_xattr_handler, &kernfs_security_xattr_handler, &kernfs_user_xattr_handler, NULL };