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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * fs/kernfs/inode.c - kernfs inode implementation
4 *
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>
8 */
9
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>
17
18#include "kernfs-internal.h"
19
20static 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,
25};
26
27static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc)
28{
29 static DEFINE_MUTEX(iattr_mutex);
30 struct kernfs_iattrs *ret;
31
32 mutex_lock(&iattr_mutex);
33
34 if (kn->iattr || !alloc)
35 goto out_unlock;
36
37 kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
38 if (!kn->iattr)
39 goto out_unlock;
40
41 /* assign default attributes */
42 kn->iattr->ia_uid = GLOBAL_ROOT_UID;
43 kn->iattr->ia_gid = GLOBAL_ROOT_GID;
44
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;
48
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);
52out_unlock:
53 ret = kn->iattr;
54 mutex_unlock(&iattr_mutex);
55 return ret;
56}
57
58static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
59{
60 return __kernfs_iattrs(kn, 1);
61}
62
63static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
64{
65 return __kernfs_iattrs(kn, 0);
66}
67
68int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
69{
70 struct kernfs_iattrs *attrs;
71 unsigned int ia_valid = iattr->ia_valid;
72
73 attrs = kernfs_iattrs(kn);
74 if (!attrs)
75 return -ENOMEM;
76
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;
89 return 0;
90}
91
92/**
93 * kernfs_setattr - set iattr on a node
94 * @kn: target node
95 * @iattr: iattr to set
96 *
97 * Return: %0 on success, -errno on failure.
98 */
99int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
100{
101 int ret;
102 struct kernfs_root *root = kernfs_root(kn);
103
104 down_write(&root->kernfs_iattr_rwsem);
105 ret = __kernfs_setattr(kn, iattr);
106 up_write(&root->kernfs_iattr_rwsem);
107 return ret;
108}
109
110int kernfs_iop_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
111 struct iattr *iattr)
112{
113 struct inode *inode = d_inode(dentry);
114 struct kernfs_node *kn = inode->i_private;
115 struct kernfs_root *root;
116 int error;
117
118 if (!kn)
119 return -EINVAL;
120
121 root = kernfs_root(kn);
122 down_write(&root->kernfs_iattr_rwsem);
123 error = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
124 if (error)
125 goto out;
126
127 error = __kernfs_setattr(kn, iattr);
128 if (error)
129 goto out;
130
131 /* this ignores size changes */
132 setattr_copy(&nop_mnt_idmap, inode, iattr);
133
134out:
135 up_write(&root->kernfs_iattr_rwsem);
136 return error;
137}
138
139ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
140{
141 struct kernfs_node *kn = kernfs_dentry_node(dentry);
142 struct kernfs_iattrs *attrs;
143
144 attrs = kernfs_iattrs(kn);
145 if (!attrs)
146 return -ENOMEM;
147
148 return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
149}
150
151static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
152{
153 inode->i_mode = mode;
154 simple_inode_init_ts(inode);
155}
156
157static inline void set_inode_attr(struct inode *inode,
158 struct kernfs_iattrs *attrs)
159{
160 inode->i_uid = attrs->ia_uid;
161 inode->i_gid = attrs->ia_gid;
162 inode_set_atime_to_ts(inode, attrs->ia_atime);
163 inode_set_mtime_to_ts(inode, attrs->ia_mtime);
164 inode_set_ctime_to_ts(inode, attrs->ia_ctime);
165}
166
167static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
168{
169 struct kernfs_iattrs *attrs = kn->iattr;
170
171 inode->i_mode = kn->mode;
172 if (attrs)
173 /*
174 * kernfs_node has non-default attributes get them from
175 * persistent copy in kernfs_node.
176 */
177 set_inode_attr(inode, attrs);
178
179 if (kernfs_type(kn) == KERNFS_DIR)
180 set_nlink(inode, kn->dir.subdirs + 2);
181}
182
183int kernfs_iop_getattr(struct mnt_idmap *idmap,
184 const struct path *path, struct kstat *stat,
185 u32 request_mask, unsigned int query_flags)
186{
187 struct inode *inode = d_inode(path->dentry);
188 struct kernfs_node *kn = inode->i_private;
189 struct kernfs_root *root = kernfs_root(kn);
190
191 down_read(&root->kernfs_iattr_rwsem);
192 kernfs_refresh_inode(kn, inode);
193 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
194 up_read(&root->kernfs_iattr_rwsem);
195
196 return 0;
197}
198
199static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
200{
201 kernfs_get(kn);
202 inode->i_private = kn;
203 inode->i_mapping->a_ops = &ram_aops;
204 inode->i_op = &kernfs_iops;
205 inode->i_generation = kernfs_gen(kn);
206
207 set_default_inode_attr(inode, kn->mode);
208 kernfs_refresh_inode(kn, inode);
209
210 /* initialize inode according to type */
211 switch (kernfs_type(kn)) {
212 case KERNFS_DIR:
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);
217 break;
218 case KERNFS_FILE:
219 inode->i_size = kn->attr.size;
220 inode->i_fop = &kernfs_file_fops;
221 break;
222 case KERNFS_LINK:
223 inode->i_op = &kernfs_symlink_iops;
224 break;
225 default:
226 BUG();
227 }
228
229 unlock_new_inode(inode);
230}
231
232/**
233 * kernfs_get_inode - get inode for kernfs_node
234 * @sb: super block
235 * @kn: kernfs_node to allocate inode for
236 *
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
239 * locked.
240 *
241 * Locking:
242 * Kernel thread context (may sleep).
243 *
244 * Return:
245 * Pointer to allocated inode on success, %NULL on failure.
246 */
247struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
248{
249 struct inode *inode;
250
251 inode = iget_locked(sb, kernfs_ino(kn));
252 if (inode && (inode->i_state & I_NEW))
253 kernfs_init_inode(kn, inode);
254
255 return inode;
256}
257
258/*
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.
264 */
265void kernfs_evict_inode(struct inode *inode)
266{
267 struct kernfs_node *kn = inode->i_private;
268
269 truncate_inode_pages_final(&inode->i_data);
270 clear_inode(inode);
271 kernfs_put(kn);
272}
273
274int kernfs_iop_permission(struct mnt_idmap *idmap,
275 struct inode *inode, int mask)
276{
277 struct kernfs_node *kn;
278 struct kernfs_root *root;
279 int ret;
280
281 if (mask & MAY_NOT_BLOCK)
282 return -ECHILD;
283
284 kn = inode->i_private;
285 root = kernfs_root(kn);
286
287 down_read(&root->kernfs_iattr_rwsem);
288 kernfs_refresh_inode(kn, inode);
289 ret = generic_permission(&nop_mnt_idmap, inode, mask);
290 up_read(&root->kernfs_iattr_rwsem);
291
292 return ret;
293}
294
295int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
296 void *value, size_t size)
297{
298 struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
299 if (!attrs)
300 return -ENODATA;
301
302 return simple_xattr_get(&attrs->xattrs, name, value, size);
303}
304
305int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
306 const void *value, size_t size, int flags)
307{
308 struct simple_xattr *old_xattr;
309 struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
310 if (!attrs)
311 return -ENOMEM;
312
313 old_xattr = simple_xattr_set(&attrs->xattrs, name, value, size, flags);
314 if (IS_ERR(old_xattr))
315 return PTR_ERR(old_xattr);
316
317 simple_xattr_free(old_xattr);
318 return 0;
319}
320
321static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
322 struct dentry *unused, struct inode *inode,
323 const char *suffix, void *value, size_t size)
324{
325 const char *name = xattr_full_name(handler, suffix);
326 struct kernfs_node *kn = inode->i_private;
327
328 return kernfs_xattr_get(kn, name, value, size);
329}
330
331static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
332 struct mnt_idmap *idmap,
333 struct dentry *unused, struct inode *inode,
334 const char *suffix, const void *value,
335 size_t size, int flags)
336{
337 const char *name = xattr_full_name(handler, suffix);
338 struct kernfs_node *kn = inode->i_private;
339
340 return kernfs_xattr_set(kn, name, value, size, flags);
341}
342
343static int kernfs_vfs_user_xattr_add(struct kernfs_node *kn,
344 const char *full_name,
345 struct simple_xattrs *xattrs,
346 const void *value, size_t size, int flags)
347{
348 atomic_t *sz = &kn->iattr->user_xattr_size;
349 atomic_t *nr = &kn->iattr->nr_user_xattrs;
350 struct simple_xattr *old_xattr;
351 int ret;
352
353 if (atomic_inc_return(nr) > KERNFS_MAX_USER_XATTRS) {
354 ret = -ENOSPC;
355 goto dec_count_out;
356 }
357
358 if (atomic_add_return(size, sz) > KERNFS_USER_XATTR_SIZE_LIMIT) {
359 ret = -ENOSPC;
360 goto dec_size_out;
361 }
362
363 old_xattr = simple_xattr_set(xattrs, full_name, value, size, flags);
364 if (!old_xattr)
365 return 0;
366
367 if (IS_ERR(old_xattr)) {
368 ret = PTR_ERR(old_xattr);
369 goto dec_size_out;
370 }
371
372 ret = 0;
373 size = old_xattr->size;
374 simple_xattr_free(old_xattr);
375dec_size_out:
376 atomic_sub(size, sz);
377dec_count_out:
378 atomic_dec(nr);
379 return ret;
380}
381
382static int kernfs_vfs_user_xattr_rm(struct kernfs_node *kn,
383 const char *full_name,
384 struct simple_xattrs *xattrs,
385 const void *value, size_t size, int flags)
386{
387 atomic_t *sz = &kn->iattr->user_xattr_size;
388 atomic_t *nr = &kn->iattr->nr_user_xattrs;
389 struct simple_xattr *old_xattr;
390
391 old_xattr = simple_xattr_set(xattrs, full_name, value, size, flags);
392 if (!old_xattr)
393 return 0;
394
395 if (IS_ERR(old_xattr))
396 return PTR_ERR(old_xattr);
397
398 atomic_sub(old_xattr->size, sz);
399 atomic_dec(nr);
400 simple_xattr_free(old_xattr);
401 return 0;
402}
403
404static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
405 struct mnt_idmap *idmap,
406 struct dentry *unused, struct inode *inode,
407 const char *suffix, const void *value,
408 size_t size, int flags)
409{
410 const char *full_name = xattr_full_name(handler, suffix);
411 struct kernfs_node *kn = inode->i_private;
412 struct kernfs_iattrs *attrs;
413
414 if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR))
415 return -EOPNOTSUPP;
416
417 attrs = kernfs_iattrs(kn);
418 if (!attrs)
419 return -ENOMEM;
420
421 if (value)
422 return kernfs_vfs_user_xattr_add(kn, full_name, &attrs->xattrs,
423 value, size, flags);
424 else
425 return kernfs_vfs_user_xattr_rm(kn, full_name, &attrs->xattrs,
426 value, size, flags);
427
428}
429
430static const struct xattr_handler kernfs_trusted_xattr_handler = {
431 .prefix = XATTR_TRUSTED_PREFIX,
432 .get = kernfs_vfs_xattr_get,
433 .set = kernfs_vfs_xattr_set,
434};
435
436static const struct xattr_handler kernfs_security_xattr_handler = {
437 .prefix = XATTR_SECURITY_PREFIX,
438 .get = kernfs_vfs_xattr_get,
439 .set = kernfs_vfs_xattr_set,
440};
441
442static const struct xattr_handler kernfs_user_xattr_handler = {
443 .prefix = XATTR_USER_PREFIX,
444 .get = kernfs_vfs_xattr_get,
445 .set = kernfs_vfs_user_xattr_set,
446};
447
448const struct xattr_handler * const kernfs_xattr_handlers[] = {
449 &kernfs_trusted_xattr_handler,
450 &kernfs_security_xattr_handler,
451 &kernfs_user_xattr_handler,
452 NULL
453};
1/*
2 * fs/kernfs/inode.c - kernfs inode implementation
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
7 *
8 * This file is released under the GPLv2.
9 */
10
11#include <linux/pagemap.h>
12#include <linux/backing-dev.h>
13#include <linux/capability.h>
14#include <linux/errno.h>
15#include <linux/slab.h>
16#include <linux/xattr.h>
17#include <linux/security.h>
18
19#include "kernfs-internal.h"
20
21static const struct address_space_operations kernfs_aops = {
22 .readpage = simple_readpage,
23 .write_begin = simple_write_begin,
24 .write_end = simple_write_end,
25};
26
27static const struct inode_operations kernfs_iops = {
28 .permission = kernfs_iop_permission,
29 .setattr = kernfs_iop_setattr,
30 .getattr = kernfs_iop_getattr,
31 .listxattr = kernfs_iop_listxattr,
32};
33
34static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
35{
36 static DEFINE_MUTEX(iattr_mutex);
37 struct kernfs_iattrs *ret;
38 struct iattr *iattrs;
39
40 mutex_lock(&iattr_mutex);
41
42 if (kn->iattr)
43 goto out_unlock;
44
45 kn->iattr = kzalloc(sizeof(struct kernfs_iattrs), GFP_KERNEL);
46 if (!kn->iattr)
47 goto out_unlock;
48 iattrs = &kn->iattr->ia_iattr;
49
50 /* assign default attributes */
51 iattrs->ia_mode = kn->mode;
52 iattrs->ia_uid = GLOBAL_ROOT_UID;
53 iattrs->ia_gid = GLOBAL_ROOT_GID;
54
55 ktime_get_real_ts(&iattrs->ia_atime);
56 iattrs->ia_mtime = iattrs->ia_atime;
57 iattrs->ia_ctime = iattrs->ia_atime;
58
59 simple_xattrs_init(&kn->iattr->xattrs);
60out_unlock:
61 ret = kn->iattr;
62 mutex_unlock(&iattr_mutex);
63 return ret;
64}
65
66static int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
67{
68 struct kernfs_iattrs *attrs;
69 struct iattr *iattrs;
70 unsigned int ia_valid = iattr->ia_valid;
71
72 attrs = kernfs_iattrs(kn);
73 if (!attrs)
74 return -ENOMEM;
75
76 iattrs = &attrs->ia_iattr;
77
78 if (ia_valid & ATTR_UID)
79 iattrs->ia_uid = iattr->ia_uid;
80 if (ia_valid & ATTR_GID)
81 iattrs->ia_gid = iattr->ia_gid;
82 if (ia_valid & ATTR_ATIME)
83 iattrs->ia_atime = iattr->ia_atime;
84 if (ia_valid & ATTR_MTIME)
85 iattrs->ia_mtime = iattr->ia_mtime;
86 if (ia_valid & ATTR_CTIME)
87 iattrs->ia_ctime = iattr->ia_ctime;
88 if (ia_valid & ATTR_MODE) {
89 umode_t mode = iattr->ia_mode;
90 iattrs->ia_mode = kn->mode = mode;
91 }
92 return 0;
93}
94
95/**
96 * kernfs_setattr - set iattr on a node
97 * @kn: target node
98 * @iattr: iattr to set
99 *
100 * Returns 0 on success, -errno on failure.
101 */
102int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
103{
104 int ret;
105
106 mutex_lock(&kernfs_mutex);
107 ret = __kernfs_setattr(kn, iattr);
108 mutex_unlock(&kernfs_mutex);
109 return ret;
110}
111
112int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
113{
114 struct inode *inode = d_inode(dentry);
115 struct kernfs_node *kn = dentry->d_fsdata;
116 int error;
117
118 if (!kn)
119 return -EINVAL;
120
121 mutex_lock(&kernfs_mutex);
122 error = setattr_prepare(dentry, iattr);
123 if (error)
124 goto out;
125
126 error = __kernfs_setattr(kn, iattr);
127 if (error)
128 goto out;
129
130 /* this ignores size changes */
131 setattr_copy(inode, iattr);
132
133out:
134 mutex_unlock(&kernfs_mutex);
135 return error;
136}
137
138static int kernfs_node_setsecdata(struct kernfs_iattrs *attrs, void **secdata,
139 u32 *secdata_len)
140{
141 void *old_secdata;
142 size_t old_secdata_len;
143
144 old_secdata = attrs->ia_secdata;
145 old_secdata_len = attrs->ia_secdata_len;
146
147 attrs->ia_secdata = *secdata;
148 attrs->ia_secdata_len = *secdata_len;
149
150 *secdata = old_secdata;
151 *secdata_len = old_secdata_len;
152 return 0;
153}
154
155ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
156{
157 struct kernfs_node *kn = dentry->d_fsdata;
158 struct kernfs_iattrs *attrs;
159
160 attrs = kernfs_iattrs(kn);
161 if (!attrs)
162 return -ENOMEM;
163
164 return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
165}
166
167static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
168{
169 inode->i_mode = mode;
170 inode->i_atime = inode->i_mtime =
171 inode->i_ctime = current_time(inode);
172}
173
174static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
175{
176 struct super_block *sb = inode->i_sb;
177 inode->i_uid = iattr->ia_uid;
178 inode->i_gid = iattr->ia_gid;
179 inode->i_atime = timespec_trunc(iattr->ia_atime, sb->s_time_gran);
180 inode->i_mtime = timespec_trunc(iattr->ia_mtime, sb->s_time_gran);
181 inode->i_ctime = timespec_trunc(iattr->ia_ctime, sb->s_time_gran);
182}
183
184static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
185{
186 struct kernfs_iattrs *attrs = kn->iattr;
187
188 inode->i_mode = kn->mode;
189 if (attrs) {
190 /*
191 * kernfs_node has non-default attributes get them from
192 * persistent copy in kernfs_node.
193 */
194 set_inode_attr(inode, &attrs->ia_iattr);
195 security_inode_notifysecctx(inode, attrs->ia_secdata,
196 attrs->ia_secdata_len);
197 }
198
199 if (kernfs_type(kn) == KERNFS_DIR)
200 set_nlink(inode, kn->dir.subdirs + 2);
201}
202
203int kernfs_iop_getattr(struct vfsmount *mnt, struct dentry *dentry,
204 struct kstat *stat)
205{
206 struct kernfs_node *kn = dentry->d_fsdata;
207 struct inode *inode = d_inode(dentry);
208
209 mutex_lock(&kernfs_mutex);
210 kernfs_refresh_inode(kn, inode);
211 mutex_unlock(&kernfs_mutex);
212
213 generic_fillattr(inode, stat);
214 return 0;
215}
216
217static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
218{
219 kernfs_get(kn);
220 inode->i_private = kn;
221 inode->i_mapping->a_ops = &kernfs_aops;
222 inode->i_op = &kernfs_iops;
223
224 set_default_inode_attr(inode, kn->mode);
225 kernfs_refresh_inode(kn, inode);
226
227 /* initialize inode according to type */
228 switch (kernfs_type(kn)) {
229 case KERNFS_DIR:
230 inode->i_op = &kernfs_dir_iops;
231 inode->i_fop = &kernfs_dir_fops;
232 if (kn->flags & KERNFS_EMPTY_DIR)
233 make_empty_dir_inode(inode);
234 break;
235 case KERNFS_FILE:
236 inode->i_size = kn->attr.size;
237 inode->i_fop = &kernfs_file_fops;
238 break;
239 case KERNFS_LINK:
240 inode->i_op = &kernfs_symlink_iops;
241 break;
242 default:
243 BUG();
244 }
245
246 unlock_new_inode(inode);
247}
248
249/**
250 * kernfs_get_inode - get inode for kernfs_node
251 * @sb: super block
252 * @kn: kernfs_node to allocate inode for
253 *
254 * Get inode for @kn. If such inode doesn't exist, a new inode is
255 * allocated and basics are initialized. New inode is returned
256 * locked.
257 *
258 * LOCKING:
259 * Kernel thread context (may sleep).
260 *
261 * RETURNS:
262 * Pointer to allocated inode on success, NULL on failure.
263 */
264struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
265{
266 struct inode *inode;
267
268 inode = iget_locked(sb, kn->ino);
269 if (inode && (inode->i_state & I_NEW))
270 kernfs_init_inode(kn, inode);
271
272 return inode;
273}
274
275/*
276 * The kernfs_node serves as both an inode and a directory entry for
277 * kernfs. To prevent the kernfs inode numbers from being freed
278 * prematurely we take a reference to kernfs_node from the kernfs inode. A
279 * super_operations.evict_inode() implementation is needed to drop that
280 * reference upon inode destruction.
281 */
282void kernfs_evict_inode(struct inode *inode)
283{
284 struct kernfs_node *kn = inode->i_private;
285
286 truncate_inode_pages_final(&inode->i_data);
287 clear_inode(inode);
288 kernfs_put(kn);
289}
290
291int kernfs_iop_permission(struct inode *inode, int mask)
292{
293 struct kernfs_node *kn;
294
295 if (mask & MAY_NOT_BLOCK)
296 return -ECHILD;
297
298 kn = inode->i_private;
299
300 mutex_lock(&kernfs_mutex);
301 kernfs_refresh_inode(kn, inode);
302 mutex_unlock(&kernfs_mutex);
303
304 return generic_permission(inode, mask);
305}
306
307static int kernfs_xattr_get(const struct xattr_handler *handler,
308 struct dentry *unused, struct inode *inode,
309 const char *suffix, void *value, size_t size)
310{
311 const char *name = xattr_full_name(handler, suffix);
312 struct kernfs_node *kn = inode->i_private;
313 struct kernfs_iattrs *attrs;
314
315 attrs = kernfs_iattrs(kn);
316 if (!attrs)
317 return -ENOMEM;
318
319 return simple_xattr_get(&attrs->xattrs, name, value, size);
320}
321
322static int kernfs_xattr_set(const struct xattr_handler *handler,
323 struct dentry *unused, struct inode *inode,
324 const char *suffix, const void *value,
325 size_t size, int flags)
326{
327 const char *name = xattr_full_name(handler, suffix);
328 struct kernfs_node *kn = inode->i_private;
329 struct kernfs_iattrs *attrs;
330
331 attrs = kernfs_iattrs(kn);
332 if (!attrs)
333 return -ENOMEM;
334
335 return simple_xattr_set(&attrs->xattrs, name, value, size, flags);
336}
337
338static const struct xattr_handler kernfs_trusted_xattr_handler = {
339 .prefix = XATTR_TRUSTED_PREFIX,
340 .get = kernfs_xattr_get,
341 .set = kernfs_xattr_set,
342};
343
344static int kernfs_security_xattr_set(const struct xattr_handler *handler,
345 struct dentry *unused, struct inode *inode,
346 const char *suffix, const void *value,
347 size_t size, int flags)
348{
349 struct kernfs_node *kn = inode->i_private;
350 struct kernfs_iattrs *attrs;
351 void *secdata;
352 u32 secdata_len = 0;
353 int error;
354
355 attrs = kernfs_iattrs(kn);
356 if (!attrs)
357 return -ENOMEM;
358
359 error = security_inode_setsecurity(inode, suffix, value, size, flags);
360 if (error)
361 return error;
362 error = security_inode_getsecctx(inode, &secdata, &secdata_len);
363 if (error)
364 return error;
365
366 mutex_lock(&kernfs_mutex);
367 error = kernfs_node_setsecdata(attrs, &secdata, &secdata_len);
368 mutex_unlock(&kernfs_mutex);
369
370 if (secdata)
371 security_release_secctx(secdata, secdata_len);
372 return error;
373}
374
375static const struct xattr_handler kernfs_security_xattr_handler = {
376 .prefix = XATTR_SECURITY_PREFIX,
377 .get = kernfs_xattr_get,
378 .set = kernfs_security_xattr_set,
379};
380
381const struct xattr_handler *kernfs_xattr_handlers[] = {
382 &kernfs_trusted_xattr_handler,
383 &kernfs_security_xattr_handler,
384 NULL
385};