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 address_space_operations kernfs_aops = {
21 .readpage = simple_readpage,
22 .write_begin = simple_write_begin,
23 .write_end = simple_write_end,
26 static const struct inode_operations kernfs_iops = {
27 .permission = kernfs_iop_permission,
28 .setattr = kernfs_iop_setattr,
29 .getattr = kernfs_iop_getattr,
30 .listxattr = kernfs_iop_listxattr,
33 static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc)
35 static DEFINE_MUTEX(iattr_mutex);
36 struct kernfs_iattrs *ret;
38 mutex_lock(&iattr_mutex);
40 if (kn->iattr || !alloc)
43 kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
47 /* assign default attributes */
48 kn->iattr->ia_uid = GLOBAL_ROOT_UID;
49 kn->iattr->ia_gid = GLOBAL_ROOT_GID;
51 ktime_get_real_ts64(&kn->iattr->ia_atime);
52 kn->iattr->ia_mtime = kn->iattr->ia_atime;
53 kn->iattr->ia_ctime = kn->iattr->ia_atime;
55 simple_xattrs_init(&kn->iattr->xattrs);
58 mutex_unlock(&iattr_mutex);
62 static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
64 return __kernfs_iattrs(kn, 1);
67 static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
69 return __kernfs_iattrs(kn, 0);
72 int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
74 struct kernfs_iattrs *attrs;
75 unsigned int ia_valid = iattr->ia_valid;
77 attrs = kernfs_iattrs(kn);
81 if (ia_valid & ATTR_UID)
82 attrs->ia_uid = iattr->ia_uid;
83 if (ia_valid & ATTR_GID)
84 attrs->ia_gid = iattr->ia_gid;
85 if (ia_valid & ATTR_ATIME)
86 attrs->ia_atime = iattr->ia_atime;
87 if (ia_valid & ATTR_MTIME)
88 attrs->ia_mtime = iattr->ia_mtime;
89 if (ia_valid & ATTR_CTIME)
90 attrs->ia_ctime = iattr->ia_ctime;
91 if (ia_valid & ATTR_MODE)
92 kn->mode = iattr->ia_mode;
97 * kernfs_setattr - set iattr on a node
99 * @iattr: iattr to set
101 * Returns 0 on success, -errno on failure.
103 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
107 mutex_lock(&kernfs_mutex);
108 ret = __kernfs_setattr(kn, iattr);
109 mutex_unlock(&kernfs_mutex);
113 int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
115 struct inode *inode = d_inode(dentry);
116 struct kernfs_node *kn = inode->i_private;
122 mutex_lock(&kernfs_mutex);
123 error = setattr_prepare(dentry, iattr);
127 error = __kernfs_setattr(kn, iattr);
131 /* this ignores size changes */
132 setattr_copy(inode, iattr);
135 mutex_unlock(&kernfs_mutex);
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 struct super_block *sb = inode->i_sb;
162 inode->i_uid = attrs->ia_uid;
163 inode->i_gid = attrs->ia_gid;
164 inode->i_atime = timespec64_trunc(attrs->ia_atime, sb->s_time_gran);
165 inode->i_mtime = timespec64_trunc(attrs->ia_mtime, sb->s_time_gran);
166 inode->i_ctime = timespec64_trunc(attrs->ia_ctime, sb->s_time_gran);
169 static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
171 struct kernfs_iattrs *attrs = kn->iattr;
173 inode->i_mode = kn->mode;
176 * kernfs_node has non-default attributes get them from
177 * persistent copy in kernfs_node.
179 set_inode_attr(inode, attrs);
181 if (kernfs_type(kn) == KERNFS_DIR)
182 set_nlink(inode, kn->dir.subdirs + 2);
185 int kernfs_iop_getattr(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;
191 mutex_lock(&kernfs_mutex);
192 kernfs_refresh_inode(kn, inode);
193 mutex_unlock(&kernfs_mutex);
195 generic_fillattr(inode, stat);
199 static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
202 inode->i_private = kn;
203 inode->i_mapping->a_ops = &kernfs_aops;
204 inode->i_op = &kernfs_iops;
205 inode->i_generation = kn->id.generation;
207 set_default_inode_attr(inode, kn->mode);
208 kernfs_refresh_inode(kn, inode);
210 /* initialize inode according to type */
211 switch (kernfs_type(kn)) {
213 inode->i_op = &kernfs_dir_iops;
214 inode->i_fop = &kernfs_dir_fops;
215 if (kn->flags & KERNFS_EMPTY_DIR)
216 make_empty_dir_inode(inode);
219 inode->i_size = kn->attr.size;
220 inode->i_fop = &kernfs_file_fops;
223 inode->i_op = &kernfs_symlink_iops;
229 unlock_new_inode(inode);
233 * kernfs_get_inode - get inode for kernfs_node
235 * @kn: kernfs_node to allocate inode for
237 * Get inode for @kn. If such inode doesn't exist, a new inode is
238 * allocated and basics are initialized. New inode is returned
242 * Kernel thread context (may sleep).
245 * Pointer to allocated inode on success, NULL on failure.
247 struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
251 inode = iget_locked(sb, kn->id.ino);
252 if (inode && (inode->i_state & I_NEW))
253 kernfs_init_inode(kn, inode);
259 * The kernfs_node serves as both an inode and a directory entry for
260 * kernfs. To prevent the kernfs inode numbers from being freed
261 * prematurely we take a reference to kernfs_node from the kernfs inode. A
262 * super_operations.evict_inode() implementation is needed to drop that
263 * reference upon inode destruction.
265 void kernfs_evict_inode(struct inode *inode)
267 struct kernfs_node *kn = inode->i_private;
269 truncate_inode_pages_final(&inode->i_data);
274 int kernfs_iop_permission(struct inode *inode, int mask)
276 struct kernfs_node *kn;
278 if (mask & MAY_NOT_BLOCK)
281 kn = inode->i_private;
283 mutex_lock(&kernfs_mutex);
284 kernfs_refresh_inode(kn, inode);
285 mutex_unlock(&kernfs_mutex);
287 return generic_permission(inode, mask);
290 int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
291 void *value, size_t size)
293 struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
297 return simple_xattr_get(&attrs->xattrs, name, value, size);
300 int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
301 const void *value, size_t size, int flags)
303 struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
307 return simple_xattr_set(&attrs->xattrs, name, value, size, flags);
310 static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
311 struct dentry *unused, struct inode *inode,
312 const char *suffix, void *value, size_t size)
314 const char *name = xattr_full_name(handler, suffix);
315 struct kernfs_node *kn = inode->i_private;
317 return kernfs_xattr_get(kn, name, value, size);
320 static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
321 struct dentry *unused, struct inode *inode,
322 const char *suffix, const void *value,
323 size_t size, int flags)
325 const char *name = xattr_full_name(handler, suffix);
326 struct kernfs_node *kn = inode->i_private;
328 return kernfs_xattr_set(kn, name, value, size, flags);
331 static const struct xattr_handler kernfs_trusted_xattr_handler = {
332 .prefix = XATTR_TRUSTED_PREFIX,
333 .get = kernfs_vfs_xattr_get,
334 .set = kernfs_vfs_xattr_set,
337 static const struct xattr_handler kernfs_security_xattr_handler = {
338 .prefix = XATTR_SECURITY_PREFIX,
339 .get = kernfs_vfs_xattr_get,
340 .set = kernfs_vfs_xattr_set,
343 const struct xattr_handler *kernfs_xattr_handlers[] = {
344 &kernfs_trusted_xattr_handler,
345 &kernfs_security_xattr_handler,