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 * Returns 0 on success, -errno on failure.
99 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
103 down_write(&kernfs_rwsem);
104 ret = __kernfs_setattr(kn, iattr);
105 up_write(&kernfs_rwsem);
109 int kernfs_iop_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
112 struct inode *inode = d_inode(dentry);
113 struct kernfs_node *kn = inode->i_private;
119 down_write(&kernfs_rwsem);
120 error = setattr_prepare(&init_user_ns, dentry, iattr);
124 error = __kernfs_setattr(kn, iattr);
128 /* this ignores size changes */
129 setattr_copy(&init_user_ns, inode, iattr);
132 up_write(&kernfs_rwsem);
136 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
138 struct kernfs_node *kn = kernfs_dentry_node(dentry);
139 struct kernfs_iattrs *attrs;
141 attrs = kernfs_iattrs(kn);
145 return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
148 static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
150 inode->i_mode = mode;
151 inode->i_atime = inode->i_mtime =
152 inode->i_ctime = current_time(inode);
155 static inline void set_inode_attr(struct inode *inode,
156 struct kernfs_iattrs *attrs)
158 inode->i_uid = attrs->ia_uid;
159 inode->i_gid = attrs->ia_gid;
160 inode->i_atime = attrs->ia_atime;
161 inode->i_mtime = attrs->ia_mtime;
162 inode->i_ctime = attrs->ia_ctime;
165 static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
167 struct kernfs_iattrs *attrs = kn->iattr;
169 inode->i_mode = kn->mode;
172 * kernfs_node has non-default attributes get them from
173 * persistent copy in kernfs_node.
175 set_inode_attr(inode, attrs);
177 if (kernfs_type(kn) == KERNFS_DIR)
178 set_nlink(inode, kn->dir.subdirs + 2);
181 int kernfs_iop_getattr(struct user_namespace *mnt_userns,
182 const struct path *path, struct kstat *stat,
183 u32 request_mask, unsigned int query_flags)
185 struct inode *inode = d_inode(path->dentry);
186 struct kernfs_node *kn = inode->i_private;
188 down_read(&kernfs_rwsem);
189 spin_lock(&inode->i_lock);
190 kernfs_refresh_inode(kn, inode);
191 generic_fillattr(&init_user_ns, inode, stat);
192 spin_unlock(&inode->i_lock);
193 up_read(&kernfs_rwsem);
198 static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
201 inode->i_private = kn;
202 inode->i_mapping->a_ops = &ram_aops;
203 inode->i_op = &kernfs_iops;
204 inode->i_generation = kernfs_gen(kn);
206 set_default_inode_attr(inode, kn->mode);
207 kernfs_refresh_inode(kn, inode);
209 /* initialize inode according to type */
210 switch (kernfs_type(kn)) {
212 inode->i_op = &kernfs_dir_iops;
213 inode->i_fop = &kernfs_dir_fops;
214 if (kn->flags & KERNFS_EMPTY_DIR)
215 make_empty_dir_inode(inode);
218 inode->i_size = kn->attr.size;
219 inode->i_fop = &kernfs_file_fops;
222 inode->i_op = &kernfs_symlink_iops;
228 unlock_new_inode(inode);
232 * kernfs_get_inode - get inode for kernfs_node
234 * @kn: kernfs_node to allocate inode for
236 * Get inode for @kn. If such inode doesn't exist, a new inode is
237 * allocated and basics are initialized. New inode is returned
241 * Kernel thread context (may sleep).
244 * Pointer to allocated inode on success, NULL on failure.
246 struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
250 inode = iget_locked(sb, kernfs_ino(kn));
251 if (inode && (inode->i_state & I_NEW))
252 kernfs_init_inode(kn, inode);
258 * The kernfs_node serves as both an inode and a directory entry for
259 * kernfs. To prevent the kernfs inode numbers from being freed
260 * prematurely we take a reference to kernfs_node from the kernfs inode. A
261 * super_operations.evict_inode() implementation is needed to drop that
262 * reference upon inode destruction.
264 void kernfs_evict_inode(struct inode *inode)
266 struct kernfs_node *kn = inode->i_private;
268 truncate_inode_pages_final(&inode->i_data);
273 int kernfs_iop_permission(struct user_namespace *mnt_userns,
274 struct inode *inode, int mask)
276 struct kernfs_node *kn;
279 if (mask & MAY_NOT_BLOCK)
282 kn = inode->i_private;
284 down_read(&kernfs_rwsem);
285 spin_lock(&inode->i_lock);
286 kernfs_refresh_inode(kn, inode);
287 ret = generic_permission(&init_user_ns, inode, mask);
288 spin_unlock(&inode->i_lock);
289 up_read(&kernfs_rwsem);
294 int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
295 void *value, size_t size)
297 struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
301 return simple_xattr_get(&attrs->xattrs, name, value, size);
304 int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
305 const void *value, size_t size, int flags)
307 struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
311 return simple_xattr_set(&attrs->xattrs, name, value, size, flags, NULL);
314 static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
315 struct dentry *unused, struct inode *inode,
316 const char *suffix, void *value, size_t size)
318 const char *name = xattr_full_name(handler, suffix);
319 struct kernfs_node *kn = inode->i_private;
321 return kernfs_xattr_get(kn, name, value, size);
324 static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
325 struct user_namespace *mnt_userns,
326 struct dentry *unused, struct inode *inode,
327 const char *suffix, const void *value,
328 size_t size, int flags)
330 const char *name = xattr_full_name(handler, suffix);
331 struct kernfs_node *kn = inode->i_private;
333 return kernfs_xattr_set(kn, name, value, size, flags);
336 static int kernfs_vfs_user_xattr_add(struct kernfs_node *kn,
337 const char *full_name,
338 struct simple_xattrs *xattrs,
339 const void *value, size_t size, int flags)
341 atomic_t *sz = &kn->iattr->user_xattr_size;
342 atomic_t *nr = &kn->iattr->nr_user_xattrs;
343 ssize_t removed_size;
346 if (atomic_inc_return(nr) > KERNFS_MAX_USER_XATTRS) {
351 if (atomic_add_return(size, sz) > KERNFS_USER_XATTR_SIZE_LIMIT) {
356 ret = simple_xattr_set(xattrs, full_name, value, size, flags,
359 if (!ret && removed_size >= 0)
364 atomic_sub(size, sz);
370 static int kernfs_vfs_user_xattr_rm(struct kernfs_node *kn,
371 const char *full_name,
372 struct simple_xattrs *xattrs,
373 const void *value, size_t size, int flags)
375 atomic_t *sz = &kn->iattr->user_xattr_size;
376 atomic_t *nr = &kn->iattr->nr_user_xattrs;
377 ssize_t removed_size;
380 ret = simple_xattr_set(xattrs, full_name, value, size, flags,
383 if (removed_size >= 0) {
384 atomic_sub(removed_size, sz);
391 static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
392 struct user_namespace *mnt_userns,
393 struct dentry *unused, struct inode *inode,
394 const char *suffix, const void *value,
395 size_t size, int flags)
397 const char *full_name = xattr_full_name(handler, suffix);
398 struct kernfs_node *kn = inode->i_private;
399 struct kernfs_iattrs *attrs;
401 if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR))
404 attrs = kernfs_iattrs(kn);
409 return kernfs_vfs_user_xattr_add(kn, full_name, &attrs->xattrs,
412 return kernfs_vfs_user_xattr_rm(kn, full_name, &attrs->xattrs,
417 static const struct xattr_handler kernfs_trusted_xattr_handler = {
418 .prefix = XATTR_TRUSTED_PREFIX,
419 .get = kernfs_vfs_xattr_get,
420 .set = kernfs_vfs_xattr_set,
423 static const struct xattr_handler kernfs_security_xattr_handler = {
424 .prefix = XATTR_SECURITY_PREFIX,
425 .get = kernfs_vfs_xattr_get,
426 .set = kernfs_vfs_xattr_set,
429 static const struct xattr_handler kernfs_user_xattr_handler = {
430 .prefix = XATTR_USER_PREFIX,
431 .get = kernfs_vfs_xattr_get,
432 .set = kernfs_vfs_user_xattr_set,
435 const struct xattr_handler *kernfs_xattr_handlers[] = {
436 &kernfs_trusted_xattr_handler,
437 &kernfs_security_xattr_handler,
438 &kernfs_user_xattr_handler,