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 mutex_lock(&kernfs_mutex);
104 ret = __kernfs_setattr(kn, iattr);
105 mutex_unlock(&kernfs_mutex);
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 mutex_lock(&kernfs_mutex);
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 mutex_unlock(&kernfs_mutex);
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 mutex_lock(&kernfs_mutex);
189 kernfs_refresh_inode(kn, inode);
190 mutex_unlock(&kernfs_mutex);
192 generic_fillattr(&init_user_ns, inode, stat);
196 static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
199 inode->i_private = kn;
200 inode->i_mapping->a_ops = &ram_aops;
201 inode->i_op = &kernfs_iops;
202 inode->i_generation = kernfs_gen(kn);
204 set_default_inode_attr(inode, kn->mode);
205 kernfs_refresh_inode(kn, inode);
207 /* initialize inode according to type */
208 switch (kernfs_type(kn)) {
210 inode->i_op = &kernfs_dir_iops;
211 inode->i_fop = &kernfs_dir_fops;
212 if (kn->flags & KERNFS_EMPTY_DIR)
213 make_empty_dir_inode(inode);
216 inode->i_size = kn->attr.size;
217 inode->i_fop = &kernfs_file_fops;
220 inode->i_op = &kernfs_symlink_iops;
226 unlock_new_inode(inode);
230 * kernfs_get_inode - get inode for kernfs_node
232 * @kn: kernfs_node to allocate inode for
234 * Get inode for @kn. If such inode doesn't exist, a new inode is
235 * allocated and basics are initialized. New inode is returned
239 * Kernel thread context (may sleep).
242 * Pointer to allocated inode on success, NULL on failure.
244 struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
248 inode = iget_locked(sb, kernfs_ino(kn));
249 if (inode && (inode->i_state & I_NEW))
250 kernfs_init_inode(kn, inode);
256 * The kernfs_node serves as both an inode and a directory entry for
257 * kernfs. To prevent the kernfs inode numbers from being freed
258 * prematurely we take a reference to kernfs_node from the kernfs inode. A
259 * super_operations.evict_inode() implementation is needed to drop that
260 * reference upon inode destruction.
262 void kernfs_evict_inode(struct inode *inode)
264 struct kernfs_node *kn = inode->i_private;
266 truncate_inode_pages_final(&inode->i_data);
271 int kernfs_iop_permission(struct user_namespace *mnt_userns,
272 struct inode *inode, int mask)
274 struct kernfs_node *kn;
276 if (mask & MAY_NOT_BLOCK)
279 kn = inode->i_private;
281 mutex_lock(&kernfs_mutex);
282 kernfs_refresh_inode(kn, inode);
283 mutex_unlock(&kernfs_mutex);
285 return generic_permission(&init_user_ns, inode, mask);
288 int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
289 void *value, size_t size)
291 struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
295 return simple_xattr_get(&attrs->xattrs, name, value, size);
298 int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
299 const void *value, size_t size, int flags)
301 struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
305 return simple_xattr_set(&attrs->xattrs, name, value, size, flags, NULL);
308 static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
309 struct dentry *unused, struct inode *inode,
310 const char *suffix, void *value, size_t size)
312 const char *name = xattr_full_name(handler, suffix);
313 struct kernfs_node *kn = inode->i_private;
315 return kernfs_xattr_get(kn, name, value, size);
318 static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
319 struct user_namespace *mnt_userns,
320 struct dentry *unused, struct inode *inode,
321 const char *suffix, const void *value,
322 size_t size, int flags)
324 const char *name = xattr_full_name(handler, suffix);
325 struct kernfs_node *kn = inode->i_private;
327 return kernfs_xattr_set(kn, name, value, size, flags);
330 static int kernfs_vfs_user_xattr_add(struct kernfs_node *kn,
331 const char *full_name,
332 struct simple_xattrs *xattrs,
333 const void *value, size_t size, int flags)
335 atomic_t *sz = &kn->iattr->user_xattr_size;
336 atomic_t *nr = &kn->iattr->nr_user_xattrs;
337 ssize_t removed_size;
340 if (atomic_inc_return(nr) > KERNFS_MAX_USER_XATTRS) {
345 if (atomic_add_return(size, sz) > KERNFS_USER_XATTR_SIZE_LIMIT) {
350 ret = simple_xattr_set(xattrs, full_name, value, size, flags,
353 if (!ret && removed_size >= 0)
358 atomic_sub(size, sz);
364 static int kernfs_vfs_user_xattr_rm(struct kernfs_node *kn,
365 const char *full_name,
366 struct simple_xattrs *xattrs,
367 const void *value, size_t size, int flags)
369 atomic_t *sz = &kn->iattr->user_xattr_size;
370 atomic_t *nr = &kn->iattr->nr_user_xattrs;
371 ssize_t removed_size;
374 ret = simple_xattr_set(xattrs, full_name, value, size, flags,
377 if (removed_size >= 0) {
378 atomic_sub(removed_size, sz);
385 static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
386 struct user_namespace *mnt_userns,
387 struct dentry *unused, struct inode *inode,
388 const char *suffix, const void *value,
389 size_t size, int flags)
391 const char *full_name = xattr_full_name(handler, suffix);
392 struct kernfs_node *kn = inode->i_private;
393 struct kernfs_iattrs *attrs;
395 if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR))
398 attrs = kernfs_iattrs(kn);
403 return kernfs_vfs_user_xattr_add(kn, full_name, &attrs->xattrs,
406 return kernfs_vfs_user_xattr_rm(kn, full_name, &attrs->xattrs,
411 static const struct xattr_handler kernfs_trusted_xattr_handler = {
412 .prefix = XATTR_TRUSTED_PREFIX,
413 .get = kernfs_vfs_xattr_get,
414 .set = kernfs_vfs_xattr_set,
417 static const struct xattr_handler kernfs_security_xattr_handler = {
418 .prefix = XATTR_SECURITY_PREFIX,
419 .get = kernfs_vfs_xattr_get,
420 .set = kernfs_vfs_xattr_set,
423 static const struct xattr_handler kernfs_user_xattr_handler = {
424 .prefix = XATTR_USER_PREFIX,
425 .get = kernfs_vfs_xattr_get,
426 .set = kernfs_vfs_user_xattr_set,
429 const struct xattr_handler *kernfs_xattr_handlers[] = {
430 &kernfs_trusted_xattr_handler,
431 &kernfs_security_xattr_handler,
432 &kernfs_user_xattr_handler,