Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * fs/sysfs/file.c - sysfs regular (text) file implementation
4 : *
5 : * Copyright (c) 2001-3 Patrick Mochel
6 : * Copyright (c) 2007 SUSE Linux Products GmbH
7 : * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
8 : *
9 : * Please see Documentation/filesystems/sysfs.rst for more information.
10 : */
11 :
12 : #include <linux/module.h>
13 : #include <linux/kobject.h>
14 : #include <linux/slab.h>
15 : #include <linux/list.h>
16 : #include <linux/mutex.h>
17 : #include <linux/seq_file.h>
18 : #include <linux/mm.h>
19 :
20 : #include "sysfs.h"
21 :
22 : /*
23 : * Determine ktype->sysfs_ops for the given kernfs_node. This function
24 : * must be called while holding an active reference.
25 : */
26 681 : static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn)
27 : {
28 681 : struct kobject *kobj = kn->parent->priv;
29 :
30 681 : if (kn->flags & KERNFS_LOCKDEP)
31 1362 : lockdep_assert_held(kn);
32 681 : return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
33 : }
34 :
35 : /*
36 : * Reads on sysfs are handled through seq_file, which takes care of hairy
37 : * details like buffering and seeking. The following function pipes
38 : * sysfs_ops->show() result through seq_file.
39 : */
40 510 : static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
41 : {
42 510 : struct kernfs_open_file *of = sf->private;
43 510 : struct kobject *kobj = of->kn->parent->priv;
44 510 : const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
45 510 : ssize_t count;
46 510 : char *buf;
47 :
48 : /* acquire buffer and ensure that it's >= PAGE_SIZE and clear */
49 510 : count = seq_get_buf(sf, &buf);
50 510 : if (count < PAGE_SIZE) {
51 0 : seq_commit(sf, -1);
52 0 : return 0;
53 : }
54 510 : memset(buf, 0, PAGE_SIZE);
55 :
56 : /*
57 : * Invoke show(). Control may reach here via seq file lseek even
58 : * if @ops->show() isn't implemented.
59 : */
60 510 : if (ops->show) {
61 510 : count = ops->show(kobj, of->kn->priv, buf);
62 510 : if (count < 0)
63 2 : return count;
64 : }
65 :
66 : /*
67 : * The code works fine with PAGE_SIZE return but it's likely to
68 : * indicate truncated result or overflow in normal use cases.
69 : */
70 508 : if (count >= (ssize_t)PAGE_SIZE) {
71 0 : printk("fill_read_buffer: %pS returned bad count\n",
72 : ops->show);
73 : /* Try to struggle along */
74 0 : count = PAGE_SIZE - 1;
75 : }
76 508 : seq_commit(sf, count);
77 508 : return 0;
78 : }
79 :
80 0 : static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf,
81 : size_t count, loff_t pos)
82 : {
83 0 : struct bin_attribute *battr = of->kn->priv;
84 0 : struct kobject *kobj = of->kn->parent->priv;
85 0 : loff_t size = file_inode(of->file)->i_size;
86 :
87 0 : if (!count)
88 : return 0;
89 :
90 0 : if (size) {
91 0 : if (pos >= size)
92 : return 0;
93 0 : if (pos + count > size)
94 0 : count = size - pos;
95 : }
96 :
97 0 : if (!battr->read)
98 : return -EIO;
99 :
100 0 : return battr->read(of->file, kobj, battr, buf, pos, count);
101 : }
102 :
103 : /* kernfs read callback for regular sysfs files with pre-alloc */
104 0 : static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
105 : size_t count, loff_t pos)
106 : {
107 0 : const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
108 0 : struct kobject *kobj = of->kn->parent->priv;
109 0 : ssize_t len;
110 :
111 : /*
112 : * If buf != of->prealloc_buf, we don't know how
113 : * large it is, so cannot safely pass it to ->show
114 : */
115 0 : if (WARN_ON_ONCE(buf != of->prealloc_buf))
116 : return 0;
117 0 : len = ops->show(kobj, of->kn->priv, buf);
118 0 : if (len < 0)
119 : return len;
120 0 : if (pos) {
121 0 : if (len <= pos)
122 : return 0;
123 0 : len -= pos;
124 0 : memmove(buf, buf + pos, len);
125 : }
126 0 : return min_t(ssize_t, count, len);
127 : }
128 :
129 : /* kernfs write callback for regular sysfs files */
130 171 : static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf,
131 : size_t count, loff_t pos)
132 : {
133 171 : const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
134 171 : struct kobject *kobj = of->kn->parent->priv;
135 :
136 171 : if (!count)
137 : return 0;
138 :
139 171 : return ops->store(kobj, of->kn->priv, buf, count);
140 : }
141 :
142 : /* kernfs write callback for bin sysfs files */
143 0 : static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf,
144 : size_t count, loff_t pos)
145 : {
146 0 : struct bin_attribute *battr = of->kn->priv;
147 0 : struct kobject *kobj = of->kn->parent->priv;
148 0 : loff_t size = file_inode(of->file)->i_size;
149 :
150 0 : if (size) {
151 0 : if (size <= pos)
152 : return -EFBIG;
153 0 : count = min_t(ssize_t, count, size - pos);
154 : }
155 0 : if (!count)
156 : return 0;
157 :
158 0 : if (!battr->write)
159 : return -EIO;
160 :
161 0 : return battr->write(of->file, kobj, battr, buf, pos, count);
162 : }
163 :
164 0 : static int sysfs_kf_bin_mmap(struct kernfs_open_file *of,
165 : struct vm_area_struct *vma)
166 : {
167 0 : struct bin_attribute *battr = of->kn->priv;
168 0 : struct kobject *kobj = of->kn->parent->priv;
169 :
170 0 : return battr->mmap(of->file, kobj, battr, vma);
171 : }
172 :
173 0 : static int sysfs_kf_bin_open(struct kernfs_open_file *of)
174 : {
175 0 : struct bin_attribute *battr = of->kn->priv;
176 :
177 0 : if (battr->mapping)
178 0 : of->file->f_mapping = battr->mapping;
179 :
180 0 : return 0;
181 : }
182 :
183 0 : void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr)
184 : {
185 0 : struct kernfs_node *kn = kobj->sd, *tmp;
186 :
187 0 : if (kn && dir)
188 0 : kn = kernfs_find_and_get(kn, dir);
189 : else
190 0 : kernfs_get(kn);
191 :
192 0 : if (kn && attr) {
193 0 : tmp = kernfs_find_and_get(kn, attr);
194 0 : kernfs_put(kn);
195 0 : kn = tmp;
196 : }
197 :
198 0 : if (kn) {
199 0 : kernfs_notify(kn);
200 0 : kernfs_put(kn);
201 : }
202 0 : }
203 : EXPORT_SYMBOL_GPL(sysfs_notify);
204 :
205 : static const struct kernfs_ops sysfs_file_kfops_empty = {
206 : };
207 :
208 : static const struct kernfs_ops sysfs_file_kfops_ro = {
209 : .seq_show = sysfs_kf_seq_show,
210 : };
211 :
212 : static const struct kernfs_ops sysfs_file_kfops_wo = {
213 : .write = sysfs_kf_write,
214 : };
215 :
216 : static const struct kernfs_ops sysfs_file_kfops_rw = {
217 : .seq_show = sysfs_kf_seq_show,
218 : .write = sysfs_kf_write,
219 : };
220 :
221 : static const struct kernfs_ops sysfs_prealloc_kfops_ro = {
222 : .read = sysfs_kf_read,
223 : .prealloc = true,
224 : };
225 :
226 : static const struct kernfs_ops sysfs_prealloc_kfops_wo = {
227 : .write = sysfs_kf_write,
228 : .prealloc = true,
229 : };
230 :
231 : static const struct kernfs_ops sysfs_prealloc_kfops_rw = {
232 : .read = sysfs_kf_read,
233 : .write = sysfs_kf_write,
234 : .prealloc = true,
235 : };
236 :
237 : static const struct kernfs_ops sysfs_bin_kfops_ro = {
238 : .read = sysfs_kf_bin_read,
239 : };
240 :
241 : static const struct kernfs_ops sysfs_bin_kfops_wo = {
242 : .write = sysfs_kf_bin_write,
243 : };
244 :
245 : static const struct kernfs_ops sysfs_bin_kfops_rw = {
246 : .read = sysfs_kf_bin_read,
247 : .write = sysfs_kf_bin_write,
248 : };
249 :
250 : static const struct kernfs_ops sysfs_bin_kfops_mmap = {
251 : .read = sysfs_kf_bin_read,
252 : .write = sysfs_kf_bin_write,
253 : .mmap = sysfs_kf_bin_mmap,
254 : .open = sysfs_kf_bin_open,
255 : };
256 :
257 6515 : int sysfs_add_file_mode_ns(struct kernfs_node *parent,
258 : const struct attribute *attr, bool is_bin,
259 : umode_t mode, kuid_t uid, kgid_t gid, const void *ns)
260 : {
261 6515 : struct lock_class_key *key = NULL;
262 6515 : const struct kernfs_ops *ops;
263 6515 : struct kernfs_node *kn;
264 6515 : loff_t size;
265 :
266 6515 : if (!is_bin) {
267 6513 : struct kobject *kobj = parent->priv;
268 6513 : const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
269 :
270 : /* every kobject with an attribute needs a ktype assigned */
271 6513 : if (WARN(!sysfs_ops, KERN_ERR
272 : "missing sysfs attribute operations for kobject: %s\n",
273 : kobject_name(kobj)))
274 : return -EINVAL;
275 :
276 6513 : if (sysfs_ops->show && sysfs_ops->store) {
277 6513 : if (mode & SYSFS_PREALLOC)
278 : ops = &sysfs_prealloc_kfops_rw;
279 : else
280 6513 : ops = &sysfs_file_kfops_rw;
281 0 : } else if (sysfs_ops->show) {
282 0 : if (mode & SYSFS_PREALLOC)
283 : ops = &sysfs_prealloc_kfops_ro;
284 : else
285 0 : ops = &sysfs_file_kfops_ro;
286 0 : } else if (sysfs_ops->store) {
287 0 : if (mode & SYSFS_PREALLOC)
288 : ops = &sysfs_prealloc_kfops_wo;
289 : else
290 0 : ops = &sysfs_file_kfops_wo;
291 : } else
292 : ops = &sysfs_file_kfops_empty;
293 :
294 : size = PAGE_SIZE;
295 : } else {
296 2 : struct bin_attribute *battr = (void *)attr;
297 :
298 2 : if (battr->mmap)
299 : ops = &sysfs_bin_kfops_mmap;
300 2 : else if (battr->read && battr->write)
301 : ops = &sysfs_bin_kfops_rw;
302 2 : else if (battr->read)
303 : ops = &sysfs_bin_kfops_ro;
304 0 : else if (battr->write)
305 : ops = &sysfs_bin_kfops_wo;
306 : else
307 0 : ops = &sysfs_file_kfops_empty;
308 :
309 2 : size = battr->size;
310 : }
311 :
312 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
313 6515 : if (!attr->ignore_lockdep)
314 6487 : key = attr->key ?: (struct lock_class_key *)&attr->skey;
315 : #endif
316 :
317 6515 : kn = __kernfs_create_file(parent, attr->name, mode & 0777, uid, gid,
318 : size, ops, (void *)attr, ns, key);
319 6515 : if (IS_ERR(kn)) {
320 0 : if (PTR_ERR(kn) == -EEXIST)
321 0 : sysfs_warn_dup(parent, attr->name);
322 0 : return PTR_ERR(kn);
323 : }
324 : return 0;
325 : }
326 :
327 : /**
328 : * sysfs_create_file_ns - create an attribute file for an object with custom ns
329 : * @kobj: object we're creating for
330 : * @attr: attribute descriptor
331 : * @ns: namespace the new file should belong to
332 : */
333 405 : int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
334 : const void *ns)
335 : {
336 405 : kuid_t uid;
337 405 : kgid_t gid;
338 :
339 810 : if (WARN_ON(!kobj || !kobj->sd || !attr))
340 : return -EINVAL;
341 :
342 405 : kobject_get_ownership(kobj, &uid, &gid);
343 405 : return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode,
344 : uid, gid, ns);
345 :
346 : }
347 : EXPORT_SYMBOL_GPL(sysfs_create_file_ns);
348 :
349 9 : int sysfs_create_files(struct kobject *kobj, const struct attribute * const *ptr)
350 : {
351 9 : int err = 0;
352 9 : int i;
353 :
354 36 : for (i = 0; ptr[i] && !err; i++)
355 27 : err = sysfs_create_file(kobj, ptr[i]);
356 9 : if (err)
357 0 : while (--i >= 0)
358 0 : sysfs_remove_file(kobj, ptr[i]);
359 9 : return err;
360 : }
361 : EXPORT_SYMBOL_GPL(sysfs_create_files);
362 :
363 : /**
364 : * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
365 : * @kobj: object we're acting for.
366 : * @attr: attribute descriptor.
367 : * @group: group name.
368 : */
369 0 : int sysfs_add_file_to_group(struct kobject *kobj,
370 : const struct attribute *attr, const char *group)
371 : {
372 0 : struct kernfs_node *parent;
373 0 : kuid_t uid;
374 0 : kgid_t gid;
375 0 : int error;
376 :
377 0 : if (group) {
378 0 : parent = kernfs_find_and_get(kobj->sd, group);
379 : } else {
380 0 : parent = kobj->sd;
381 0 : kernfs_get(parent);
382 : }
383 :
384 0 : if (!parent)
385 : return -ENOENT;
386 :
387 0 : kobject_get_ownership(kobj, &uid, &gid);
388 0 : error = sysfs_add_file_mode_ns(parent, attr, false,
389 0 : attr->mode, uid, gid, NULL);
390 0 : kernfs_put(parent);
391 :
392 0 : return error;
393 : }
394 : EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
395 :
396 : /**
397 : * sysfs_chmod_file - update the modified mode value on an object attribute.
398 : * @kobj: object we're acting for.
399 : * @attr: attribute descriptor.
400 : * @mode: file permissions.
401 : *
402 : */
403 0 : int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
404 : umode_t mode)
405 : {
406 0 : struct kernfs_node *kn;
407 0 : struct iattr newattrs;
408 0 : int rc;
409 :
410 0 : kn = kernfs_find_and_get(kobj->sd, attr->name);
411 0 : if (!kn)
412 : return -ENOENT;
413 :
414 0 : newattrs.ia_mode = (mode & S_IALLUGO) | (kn->mode & ~S_IALLUGO);
415 0 : newattrs.ia_valid = ATTR_MODE;
416 :
417 0 : rc = kernfs_setattr(kn, &newattrs);
418 :
419 0 : kernfs_put(kn);
420 0 : return rc;
421 : }
422 : EXPORT_SYMBOL_GPL(sysfs_chmod_file);
423 :
424 : /**
425 : * sysfs_break_active_protection - break "active" protection
426 : * @kobj: The kernel object @attr is associated with.
427 : * @attr: The attribute to break the "active" protection for.
428 : *
429 : * With sysfs, just like kernfs, deletion of an attribute is postponed until
430 : * all active .show() and .store() callbacks have finished unless this function
431 : * is called. Hence this function is useful in methods that implement self
432 : * deletion.
433 : */
434 0 : struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
435 : const struct attribute *attr)
436 : {
437 0 : struct kernfs_node *kn;
438 :
439 0 : kobject_get(kobj);
440 0 : kn = kernfs_find_and_get(kobj->sd, attr->name);
441 0 : if (kn)
442 0 : kernfs_break_active_protection(kn);
443 0 : return kn;
444 : }
445 : EXPORT_SYMBOL_GPL(sysfs_break_active_protection);
446 :
447 : /**
448 : * sysfs_unbreak_active_protection - restore "active" protection
449 : * @kn: Pointer returned by sysfs_break_active_protection().
450 : *
451 : * Undo the effects of sysfs_break_active_protection(). Since this function
452 : * calls kernfs_put() on the kernfs node that corresponds to the 'attr'
453 : * argument passed to sysfs_break_active_protection() that attribute may have
454 : * been removed between the sysfs_break_active_protection() and
455 : * sysfs_unbreak_active_protection() calls, it is not safe to access @kn after
456 : * this function has returned.
457 : */
458 0 : void sysfs_unbreak_active_protection(struct kernfs_node *kn)
459 : {
460 0 : struct kobject *kobj = kn->parent->priv;
461 :
462 0 : kernfs_unbreak_active_protection(kn);
463 0 : kernfs_put(kn);
464 0 : kobject_put(kobj);
465 0 : }
466 : EXPORT_SYMBOL_GPL(sysfs_unbreak_active_protection);
467 :
468 : /**
469 : * sysfs_remove_file_ns - remove an object attribute with a custom ns tag
470 : * @kobj: object we're acting for
471 : * @attr: attribute descriptor
472 : * @ns: namespace tag of the file to remove
473 : *
474 : * Hash the attribute name and namespace tag and kill the victim.
475 : */
476 6 : void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
477 : const void *ns)
478 : {
479 6 : struct kernfs_node *parent = kobj->sd;
480 :
481 6 : kernfs_remove_by_name_ns(parent, attr->name, ns);
482 6 : }
483 : EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);
484 :
485 : /**
486 : * sysfs_remove_file_self - remove an object attribute from its own method
487 : * @kobj: object we're acting for
488 : * @attr: attribute descriptor
489 : *
490 : * See kernfs_remove_self() for details.
491 : */
492 0 : bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr)
493 : {
494 0 : struct kernfs_node *parent = kobj->sd;
495 0 : struct kernfs_node *kn;
496 0 : bool ret;
497 :
498 0 : kn = kernfs_find_and_get(parent, attr->name);
499 0 : if (WARN_ON_ONCE(!kn))
500 : return false;
501 :
502 0 : ret = kernfs_remove_self(kn);
503 :
504 0 : kernfs_put(kn);
505 0 : return ret;
506 : }
507 : EXPORT_SYMBOL_GPL(sysfs_remove_file_self);
508 :
509 0 : void sysfs_remove_files(struct kobject *kobj, const struct attribute * const *ptr)
510 : {
511 0 : int i;
512 :
513 0 : for (i = 0; ptr[i]; i++)
514 0 : sysfs_remove_file(kobj, ptr[i]);
515 0 : }
516 : EXPORT_SYMBOL_GPL(sysfs_remove_files);
517 :
518 : /**
519 : * sysfs_remove_file_from_group - remove an attribute file from a group.
520 : * @kobj: object we're acting for.
521 : * @attr: attribute descriptor.
522 : * @group: group name.
523 : */
524 0 : void sysfs_remove_file_from_group(struct kobject *kobj,
525 : const struct attribute *attr, const char *group)
526 : {
527 0 : struct kernfs_node *parent;
528 :
529 0 : if (group) {
530 0 : parent = kernfs_find_and_get(kobj->sd, group);
531 : } else {
532 0 : parent = kobj->sd;
533 0 : kernfs_get(parent);
534 : }
535 :
536 0 : if (parent) {
537 0 : kernfs_remove_by_name(parent, attr->name);
538 0 : kernfs_put(parent);
539 : }
540 0 : }
541 : EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
542 :
543 : /**
544 : * sysfs_create_bin_file - create binary file for object.
545 : * @kobj: object.
546 : * @attr: attribute descriptor.
547 : */
548 1 : int sysfs_create_bin_file(struct kobject *kobj,
549 : const struct bin_attribute *attr)
550 : {
551 1 : kuid_t uid;
552 1 : kgid_t gid;
553 :
554 2 : if (WARN_ON(!kobj || !kobj->sd || !attr))
555 : return -EINVAL;
556 :
557 1 : kobject_get_ownership(kobj, &uid, &gid);
558 1 : return sysfs_add_file_mode_ns(kobj->sd, &attr->attr, true,
559 1 : attr->attr.mode, uid, gid, NULL);
560 : }
561 : EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
562 :
563 : /**
564 : * sysfs_remove_bin_file - remove binary file for object.
565 : * @kobj: object.
566 : * @attr: attribute descriptor.
567 : */
568 0 : void sysfs_remove_bin_file(struct kobject *kobj,
569 : const struct bin_attribute *attr)
570 : {
571 0 : kernfs_remove_by_name(kobj->sd, attr->attr.name);
572 0 : }
573 : EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);
574 :
575 0 : static int internal_change_owner(struct kernfs_node *kn, kuid_t kuid,
576 : kgid_t kgid)
577 : {
578 0 : struct iattr newattrs = {
579 : .ia_valid = ATTR_UID | ATTR_GID,
580 : .ia_uid = kuid,
581 : .ia_gid = kgid,
582 : };
583 0 : return kernfs_setattr(kn, &newattrs);
584 : }
585 :
586 : /**
587 : * sysfs_link_change_owner - change owner of a sysfs file.
588 : * @kobj: object of the kernfs_node the symlink is located in.
589 : * @targ: object of the kernfs_node the symlink points to.
590 : * @name: name of the link.
591 : * @kuid: new owner's kuid
592 : * @kgid: new owner's kgid
593 : *
594 : * This function looks up the sysfs symlink entry @name under @kobj and changes
595 : * the ownership to @kuid/@kgid. The symlink is looked up in the namespace of
596 : * @targ.
597 : *
598 : * Returns 0 on success or error code on failure.
599 : */
600 0 : int sysfs_link_change_owner(struct kobject *kobj, struct kobject *targ,
601 : const char *name, kuid_t kuid, kgid_t kgid)
602 : {
603 0 : struct kernfs_node *kn = NULL;
604 0 : int error;
605 :
606 0 : if (!name || !kobj->state_in_sysfs || !targ->state_in_sysfs)
607 : return -EINVAL;
608 :
609 0 : error = -ENOENT;
610 0 : kn = kernfs_find_and_get_ns(kobj->sd, name, targ->sd->ns);
611 0 : if (!kn)
612 0 : goto out;
613 :
614 0 : error = -EINVAL;
615 0 : if (kernfs_type(kn) != KERNFS_LINK)
616 0 : goto out;
617 0 : if (kn->symlink.target_kn->priv != targ)
618 0 : goto out;
619 :
620 0 : error = internal_change_owner(kn, kuid, kgid);
621 :
622 0 : out:
623 0 : kernfs_put(kn);
624 0 : return error;
625 : }
626 :
627 : /**
628 : * sysfs_file_change_owner - change owner of a sysfs file.
629 : * @kobj: object.
630 : * @name: name of the file to change.
631 : * @kuid: new owner's kuid
632 : * @kgid: new owner's kgid
633 : *
634 : * This function looks up the sysfs entry @name under @kobj and changes the
635 : * ownership to @kuid/@kgid.
636 : *
637 : * Returns 0 on success or error code on failure.
638 : */
639 0 : int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid,
640 : kgid_t kgid)
641 : {
642 0 : struct kernfs_node *kn;
643 0 : int error;
644 :
645 0 : if (!name)
646 : return -EINVAL;
647 :
648 0 : if (!kobj->state_in_sysfs)
649 : return -EINVAL;
650 :
651 0 : kn = kernfs_find_and_get(kobj->sd, name);
652 0 : if (!kn)
653 : return -ENOENT;
654 :
655 0 : error = internal_change_owner(kn, kuid, kgid);
656 :
657 0 : kernfs_put(kn);
658 :
659 0 : return error;
660 : }
661 : EXPORT_SYMBOL_GPL(sysfs_file_change_owner);
662 :
663 : /**
664 : * sysfs_change_owner - change owner of the given object.
665 : * @kobj: object.
666 : * @kuid: new owner's kuid
667 : * @kgid: new owner's kgid
668 : *
669 : * Change the owner of the default directory, files, groups, and attributes of
670 : * @kobj to @kuid/@kgid. Note that sysfs_change_owner mirrors how the sysfs
671 : * entries for a kobject are added by driver core. In summary,
672 : * sysfs_change_owner() takes care of the default directory entry for @kobj,
673 : * the default attributes associated with the ktype of @kobj and the default
674 : * attributes associated with the ktype of @kobj.
675 : * Additional properties not added by driver core have to be changed by the
676 : * driver or subsystem which created them. This is similar to how
677 : * driver/subsystem specific entries are removed.
678 : *
679 : * Returns 0 on success or error code on failure.
680 : */
681 0 : int sysfs_change_owner(struct kobject *kobj, kuid_t kuid, kgid_t kgid)
682 : {
683 0 : int error;
684 0 : const struct kobj_type *ktype;
685 :
686 0 : if (!kobj->state_in_sysfs)
687 : return -EINVAL;
688 :
689 : /* Change the owner of the kobject itself. */
690 0 : error = internal_change_owner(kobj->sd, kuid, kgid);
691 0 : if (error)
692 : return error;
693 :
694 0 : ktype = get_ktype(kobj);
695 0 : if (ktype) {
696 0 : struct attribute **kattr;
697 :
698 : /*
699 : * Change owner of the default attributes associated with the
700 : * ktype of @kobj.
701 : */
702 0 : for (kattr = ktype->default_attrs; kattr && *kattr; kattr++) {
703 0 : error = sysfs_file_change_owner(kobj, (*kattr)->name,
704 : kuid, kgid);
705 0 : if (error)
706 0 : return error;
707 : }
708 :
709 : /*
710 : * Change owner of the default groups associated with the
711 : * ktype of @kobj.
712 : */
713 0 : error = sysfs_groups_change_owner(kobj, ktype->default_groups,
714 : kuid, kgid);
715 0 : if (error)
716 0 : return error;
717 : }
718 :
719 : return 0;
720 : }
721 : EXPORT_SYMBOL_GPL(sysfs_change_owner);
722 :
723 : /**
724 : * sysfs_emit - scnprintf equivalent, aware of PAGE_SIZE buffer.
725 : * @buf: start of PAGE_SIZE buffer.
726 : * @fmt: format
727 : * @...: optional arguments to @format
728 : *
729 : *
730 : * Returns number of characters written to @buf.
731 : */
732 0 : int sysfs_emit(char *buf, const char *fmt, ...)
733 : {
734 0 : va_list args;
735 0 : int len;
736 :
737 0 : if (WARN(!buf || offset_in_page(buf),
738 : "invalid sysfs_emit: buf:%p\n", buf))
739 : return 0;
740 :
741 0 : va_start(args, fmt);
742 0 : len = vscnprintf(buf, PAGE_SIZE, fmt, args);
743 0 : va_end(args);
744 :
745 0 : return len;
746 : }
747 : EXPORT_SYMBOL_GPL(sysfs_emit);
748 :
749 : /**
750 : * sysfs_emit_at - scnprintf equivalent, aware of PAGE_SIZE buffer.
751 : * @buf: start of PAGE_SIZE buffer.
752 : * @at: offset in @buf to start write in bytes
753 : * @at must be >= 0 && < PAGE_SIZE
754 : * @fmt: format
755 : * @...: optional arguments to @fmt
756 : *
757 : *
758 : * Returns number of characters written starting at &@buf[@at].
759 : */
760 2968 : int sysfs_emit_at(char *buf, int at, const char *fmt, ...)
761 : {
762 2968 : va_list args;
763 2968 : int len;
764 :
765 5936 : if (WARN(!buf || offset_in_page(buf) || at < 0 || at >= PAGE_SIZE,
766 : "invalid sysfs_emit_at: buf:%p at:%d\n", buf, at))
767 : return 0;
768 :
769 2968 : va_start(args, fmt);
770 2968 : len = vscnprintf(buf + at, PAGE_SIZE - at, fmt, args);
771 2968 : va_end(args);
772 :
773 2968 : return len;
774 : }
775 : EXPORT_SYMBOL_GPL(sysfs_emit_at);
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