1 // SPDX-License-Identifier: GPL-2.0-only
3 * fs/kernfs/inode.c - kernfs inode implementation
5 * Copyright (c) 2001-3 Patrick Mochel
6 * Copyright (c) 2007 SUSE Linux Products GmbH
7 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
10 #include <linux/pagemap.h>
11 #include <linux/backing-dev.h>
12 #include <linux/capability.h>
13 #include <linux/errno.h>
14 #include <linux/slab.h>
15 #include <linux/xattr.h>
16 #include <linux/security.h>
18 #include "kernfs-internal.h"
20 static const struct inode_operations kernfs_iops = {
21 .permission = kernfs_iop_permission,
22 .setattr = kernfs_iop_setattr,
23 .getattr = kernfs_iop_getattr,
24 .listxattr = kernfs_iop_listxattr,
27 static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc)
29 static DEFINE_MUTEX(iattr_mutex);
30 struct kernfs_iattrs *ret;
32 mutex_lock(&iattr_mutex);
34 if (kn->iattr || !alloc)
37 kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
41 /* assign default attributes */
42 kn->iattr->ia_uid = GLOBAL_ROOT_UID;
43 kn->iattr->ia_gid = GLOBAL_ROOT_GID;
45 ktime_get_real_ts64(&kn->iattr->ia_atime);
46 kn->iattr->ia_mtime = kn->iattr->ia_atime;
47 kn->iattr->ia_ctime = kn->iattr->ia_atime;
49 simple_xattrs_init(&kn->iattr->xattrs);
50 atomic_set(&kn->iattr->nr_user_xattrs, 0);
51 atomic_set(&kn->iattr->user_xattr_size, 0);
54 mutex_unlock(&iattr_mutex);
58 static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
60 return __kernfs_iattrs(kn, 1);
63 static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
65 return __kernfs_iattrs(kn, 0);
68 int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
70 struct kernfs_iattrs *attrs;
71 unsigned int ia_valid = iattr->ia_valid;
73 attrs = kernfs_iattrs(kn);
77 if (ia_valid & ATTR_UID)
78 attrs->ia_uid = iattr->ia_uid;
79 if (ia_valid & ATTR_GID)
80 attrs->ia_gid = iattr->ia_gid;
81 if (ia_valid & ATTR_ATIME)
82 attrs->ia_atime = iattr->ia_atime;
83 if (ia_valid & ATTR_MTIME)
84 attrs->ia_mtime = iattr->ia_mtime;
85 if (ia_valid & ATTR_CTIME)
86 attrs->ia_ctime = iattr->ia_ctime;
87 if (ia_valid & ATTR_MODE)
88 kn->mode = iattr->ia_mode;
93 * kernfs_setattr - set iattr on a node
95 * @iattr: iattr to set
97 * Return: %0 on success, -errno on failure.
99 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
102 struct kernfs_root *root = kernfs_root(kn);
104 down_write(&root->kernfs_iattr_rwsem);
105 ret = __kernfs_setattr(kn, iattr);
106 up_write(&root->kernfs_iattr_rwsem);
110 int kernfs_iop_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
113 struct inode *inode = d_inode(dentry);
114 struct kernfs_node *kn = inode->i_private;
115 struct kernfs_root *root;
121 root = kernfs_root(kn);
122 down_write(&root->kernfs_iattr_rwsem);
123 error = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
127 error = __kernfs_setattr(kn, iattr);
131 /* this ignores size changes */
132 setattr_copy(&nop_mnt_idmap, inode, iattr);
135 up_write(&root->kernfs_iattr_rwsem);
139 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
141 struct kernfs_node *kn = kernfs_dentry_node(dentry);
142 struct kernfs_iattrs *attrs;
144 attrs = kernfs_iattrs(kn);
148 return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
151 static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
153 inode->i_mode = mode;
154 inode->i_atime = inode->i_mtime =
155 inode->i_ctime = current_time(inode);
158 static inline void set_inode_attr(struct inode *inode,
159 struct kernfs_iattrs *attrs)
161 inode->i_uid = attrs->ia_uid;
162 inode->i_gid = attrs->ia_gid;
163 inode->i_atime = attrs->ia_atime;
164 inode->i_mtime = attrs->ia_mtime;
165 inode->i_ctime = attrs->ia_ctime;
168 static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
170 struct kernfs_iattrs *attrs = kn->iattr;
172 inode->i_mode = kn->mode;
175 * kernfs_node has non-default attributes get them from
176 * persistent copy in kernfs_node.
178 set_inode_attr(inode, attrs);
180 if (kernfs_type(kn) == KERNFS_DIR)
181 set_nlink(inode, kn->dir.subdirs + 2);
184 int kernfs_iop_getattr(struct mnt_idmap *idmap,
185 const struct path *path, struct kstat *stat,
186 u32 request_mask, unsigned int query_flags)
188 struct inode *inode = d_inode(path->dentry);
189 struct kernfs_node *kn = inode->i_private;
190 struct kernfs_root *root = kernfs_root(kn);
192 down_read(&root->kernfs_iattr_rwsem);
193 kernfs_refresh_inode(kn, inode);
194 generic_fillattr(&nop_mnt_idmap, inode, stat);
195 up_read(&root->kernfs_iattr_rwsem);
200 static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
203 inode->i_private = kn;
204 inode->i_mapping->a_ops = &ram_aops;
205 inode->i_op = &kernfs_iops;
206 inode->i_generation = kernfs_gen(kn);
208 set_default_inode_attr(inode, kn->mode);
209 kernfs_refresh_inode(kn, inode);
211 /* initialize inode according to type */
212 switch (kernfs_type(kn)) {
214 inode->i_op = &kernfs_dir_iops;
215 inode->i_fop = &kernfs_dir_fops;
216 if (kn->flags & KERNFS_EMPTY_DIR)
217 make_empty_dir_inode(inode);
220 inode->i_size = kn->attr.size;
221 inode->i_fop = &kernfs_file_fops;
224 inode->i_op = &kernfs_symlink_iops;
230 unlock_new_inode(inode);
234 * kernfs_get_inode - get inode for kernfs_node
236 * @kn: kernfs_node to allocate inode for
238 * Get inode for @kn. If such inode doesn't exist, a new inode is
239 * allocated and basics are initialized. New inode is returned
243 * Kernel thread context (may sleep).
246 * Pointer to allocated inode on success, %NULL on failure.
248 struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
252 inode = iget_locked(sb, kernfs_ino(kn));
253 if (inode && (inode->i_state & I_NEW))
254 kernfs_init_inode(kn, inode);
260 * The kernfs_node serves as both an inode and a directory entry for
261 * kernfs. To prevent the kernfs inode numbers from being freed
262 * prematurely we take a reference to kernfs_node from the kernfs inode. A
263 * super_operations.evict_inode() implementation is needed to drop that
264 * reference upon inode destruction.
266 void kernfs_evict_inode(struct inode *inode)
268 struct kernfs_node *kn = inode->i_private;
270 truncate_inode_pages_final(&inode->i_data);
275 int kernfs_iop_permission(struct mnt_idmap *idmap,
276 struct inode *inode, int mask)
278 struct kernfs_node *kn;
279 struct kernfs_root *root;
282 if (mask & MAY_NOT_BLOCK)
285 kn = inode->i_private;
286 root = kernfs_root(kn);
288 down_read(&root->kernfs_iattr_rwsem);
289 kernfs_refresh_inode(kn, inode);
290 ret = generic_permission(&nop_mnt_idmap, inode, mask);
291 up_read(&root->kernfs_iattr_rwsem);
296 int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
297 void *value, size_t size)
299 struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
303 return simple_xattr_get(&attrs->xattrs, name, value, size);
306 int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
307 const void *value, size_t size, int flags)
309 struct simple_xattr *old_xattr;
310 struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
314 old_xattr = simple_xattr_set(&attrs->xattrs, name, value, size, flags);
315 if (IS_ERR(old_xattr))
316 return PTR_ERR(old_xattr);
318 simple_xattr_free(old_xattr);
322 static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
323 struct dentry *unused, struct inode *inode,
324 const char *suffix, void *value, size_t size)
326 const char *name = xattr_full_name(handler, suffix);
327 struct kernfs_node *kn = inode->i_private;
329 return kernfs_xattr_get(kn, name, value, size);
332 static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
333 struct mnt_idmap *idmap,
334 struct dentry *unused, struct inode *inode,
335 const char *suffix, const void *value,
336 size_t size, int flags)
338 const char *name = xattr_full_name(handler, suffix);
339 struct kernfs_node *kn = inode->i_private;
341 return kernfs_xattr_set(kn, name, value, size, flags);
344 static int kernfs_vfs_user_xattr_add(struct kernfs_node *kn,
345 const char *full_name,
346 struct simple_xattrs *xattrs,
347 const void *value, size_t size, int flags)
349 atomic_t *sz = &kn->iattr->user_xattr_size;
350 atomic_t *nr = &kn->iattr->nr_user_xattrs;
351 struct simple_xattr *old_xattr;
354 if (atomic_inc_return(nr) > KERNFS_MAX_USER_XATTRS) {
359 if (atomic_add_return(size, sz) > KERNFS_USER_XATTR_SIZE_LIMIT) {
364 old_xattr = simple_xattr_set(xattrs, full_name, value, size, flags);
368 if (IS_ERR(old_xattr)) {
369 ret = PTR_ERR(old_xattr);
374 size = old_xattr->size;
375 simple_xattr_free(old_xattr);
377 atomic_sub(size, sz);
383 static int kernfs_vfs_user_xattr_rm(struct kernfs_node *kn,
384 const char *full_name,
385 struct simple_xattrs *xattrs,
386 const void *value, size_t size, int flags)
388 atomic_t *sz = &kn->iattr->user_xattr_size;
389 atomic_t *nr = &kn->iattr->nr_user_xattrs;
390 struct simple_xattr *old_xattr;
392 old_xattr = simple_xattr_set(xattrs, full_name, value, size, flags);
396 if (IS_ERR(old_xattr))
397 return PTR_ERR(old_xattr);
399 atomic_sub(old_xattr->size, sz);
401 simple_xattr_free(old_xattr);
405 static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
406 struct mnt_idmap *idmap,
407 struct dentry *unused, struct inode *inode,
408 const char *suffix, const void *value,
409 size_t size, int flags)
411 const char *full_name = xattr_full_name(handler, suffix);
412 struct kernfs_node *kn = inode->i_private;
413 struct kernfs_iattrs *attrs;
415 if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR))
418 attrs = kernfs_iattrs(kn);
423 return kernfs_vfs_user_xattr_add(kn, full_name, &attrs->xattrs,
426 return kernfs_vfs_user_xattr_rm(kn, full_name, &attrs->xattrs,
431 static const struct xattr_handler kernfs_trusted_xattr_handler = {
432 .prefix = XATTR_TRUSTED_PREFIX,
433 .get = kernfs_vfs_xattr_get,
434 .set = kernfs_vfs_xattr_set,
437 static const struct xattr_handler kernfs_security_xattr_handler = {
438 .prefix = XATTR_SECURITY_PREFIX,
439 .get = kernfs_vfs_xattr_get,
440 .set = kernfs_vfs_xattr_set,
443 static const struct xattr_handler kernfs_user_xattr_handler = {
444 .prefix = XATTR_USER_PREFIX,
445 .get = kernfs_vfs_xattr_get,
446 .set = kernfs_vfs_user_xattr_set,
449 const struct xattr_handler *kernfs_xattr_handlers[] = {
450 &kernfs_trusted_xattr_handler,
451 &kernfs_security_xattr_handler,
452 &kernfs_user_xattr_handler,