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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 */
26static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn)
27{
28 struct kobject *kobj = kn->parent->priv;
29
30 if (kn->flags & KERNFS_LOCKDEP)
31 lockdep_assert_held(kn);
32 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 */
40static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
41{
42 struct kernfs_open_file *of = sf->private;
43 struct kobject *kobj = of->kn->parent->priv;
44 const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
45 ssize_t count;
46 char *buf;
47
48 if (WARN_ON_ONCE(!ops->show))
49 return -EINVAL;
50
51 /* acquire buffer and ensure that it's >= PAGE_SIZE and clear */
52 count = seq_get_buf(sf, &buf);
53 if (count < PAGE_SIZE) {
54 seq_commit(sf, -1);
55 return 0;
56 }
57 memset(buf, 0, PAGE_SIZE);
58
59 count = ops->show(kobj, of->kn->priv, buf);
60 if (count < 0)
61 return count;
62
63 /*
64 * The code works fine with PAGE_SIZE return but it's likely to
65 * indicate truncated result or overflow in normal use cases.
66 */
67 if (count >= (ssize_t)PAGE_SIZE) {
68 printk("fill_read_buffer: %pS returned bad count\n",
69 ops->show);
70 /* Try to struggle along */
71 count = PAGE_SIZE - 1;
72 }
73 seq_commit(sf, count);
74 return 0;
75}
76
77static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf,
78 size_t count, loff_t pos)
79{
80 struct bin_attribute *battr = of->kn->priv;
81 struct kobject *kobj = of->kn->parent->priv;
82 loff_t size = file_inode(of->file)->i_size;
83
84 if (!count)
85 return 0;
86
87 if (size) {
88 if (pos >= size)
89 return 0;
90 if (pos + count > size)
91 count = size - pos;
92 }
93
94 if (!battr->read)
95 return -EIO;
96
97 return battr->read(of->file, kobj, battr, buf, pos, count);
98}
99
100/* kernfs read callback for regular sysfs files with pre-alloc */
101static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
102 size_t count, loff_t pos)
103{
104 const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
105 struct kobject *kobj = of->kn->parent->priv;
106 ssize_t len;
107
108 /*
109 * If buf != of->prealloc_buf, we don't know how
110 * large it is, so cannot safely pass it to ->show
111 */
112 if (WARN_ON_ONCE(buf != of->prealloc_buf))
113 return 0;
114 len = ops->show(kobj, of->kn->priv, buf);
115 if (len < 0)
116 return len;
117 if (pos) {
118 if (len <= pos)
119 return 0;
120 len -= pos;
121 memmove(buf, buf + pos, len);
122 }
123 return min_t(ssize_t, count, len);
124}
125
126/* kernfs write callback for regular sysfs files */
127static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf,
128 size_t count, loff_t pos)
129{
130 const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
131 struct kobject *kobj = of->kn->parent->priv;
132
133 if (!count)
134 return 0;
135
136 return ops->store(kobj, of->kn->priv, buf, count);
137}
138
139/* kernfs write callback for bin sysfs files */
140static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf,
141 size_t count, loff_t pos)
142{
143 struct bin_attribute *battr = of->kn->priv;
144 struct kobject *kobj = of->kn->parent->priv;
145 loff_t size = file_inode(of->file)->i_size;
146
147 if (size) {
148 if (size <= pos)
149 return -EFBIG;
150 count = min_t(ssize_t, count, size - pos);
151 }
152 if (!count)
153 return 0;
154
155 if (!battr->write)
156 return -EIO;
157
158 return battr->write(of->file, kobj, battr, buf, pos, count);
159}
160
161static int sysfs_kf_bin_mmap(struct kernfs_open_file *of,
162 struct vm_area_struct *vma)
163{
164 struct bin_attribute *battr = of->kn->priv;
165 struct kobject *kobj = of->kn->parent->priv;
166
167 return battr->mmap(of->file, kobj, battr, vma);
168}
169
170static int sysfs_kf_bin_open(struct kernfs_open_file *of)
171{
172 struct bin_attribute *battr = of->kn->priv;
173
174 if (battr->f_mapping)
175 of->file->f_mapping = battr->f_mapping();
176
177 return 0;
178}
179
180void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr)
181{
182 struct kernfs_node *kn = kobj->sd, *tmp;
183
184 if (kn && dir)
185 kn = kernfs_find_and_get(kn, dir);
186 else
187 kernfs_get(kn);
188
189 if (kn && attr) {
190 tmp = kernfs_find_and_get(kn, attr);
191 kernfs_put(kn);
192 kn = tmp;
193 }
194
195 if (kn) {
196 kernfs_notify(kn);
197 kernfs_put(kn);
198 }
199}
200EXPORT_SYMBOL_GPL(sysfs_notify);
201
202static const struct kernfs_ops sysfs_file_kfops_empty = {
203};
204
205static const struct kernfs_ops sysfs_file_kfops_ro = {
206 .seq_show = sysfs_kf_seq_show,
207};
208
209static const struct kernfs_ops sysfs_file_kfops_wo = {
210 .write = sysfs_kf_write,
211};
212
213static const struct kernfs_ops sysfs_file_kfops_rw = {
214 .seq_show = sysfs_kf_seq_show,
215 .write = sysfs_kf_write,
216};
217
218static const struct kernfs_ops sysfs_prealloc_kfops_ro = {
219 .read = sysfs_kf_read,
220 .prealloc = true,
221};
222
223static const struct kernfs_ops sysfs_prealloc_kfops_wo = {
224 .write = sysfs_kf_write,
225 .prealloc = true,
226};
227
228static const struct kernfs_ops sysfs_prealloc_kfops_rw = {
229 .read = sysfs_kf_read,
230 .write = sysfs_kf_write,
231 .prealloc = true,
232};
233
234static const struct kernfs_ops sysfs_bin_kfops_ro = {
235 .read = sysfs_kf_bin_read,
236};
237
238static const struct kernfs_ops sysfs_bin_kfops_wo = {
239 .write = sysfs_kf_bin_write,
240};
241
242static const struct kernfs_ops sysfs_bin_kfops_rw = {
243 .read = sysfs_kf_bin_read,
244 .write = sysfs_kf_bin_write,
245};
246
247static const struct kernfs_ops sysfs_bin_kfops_mmap = {
248 .read = sysfs_kf_bin_read,
249 .write = sysfs_kf_bin_write,
250 .mmap = sysfs_kf_bin_mmap,
251 .open = sysfs_kf_bin_open,
252};
253
254int sysfs_add_file_mode_ns(struct kernfs_node *parent,
255 const struct attribute *attr, umode_t mode, kuid_t uid,
256 kgid_t gid, const void *ns)
257{
258 struct kobject *kobj = parent->priv;
259 const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
260 struct lock_class_key *key = NULL;
261 const struct kernfs_ops *ops = NULL;
262 struct kernfs_node *kn;
263
264 /* every kobject with an attribute needs a ktype assigned */
265 if (WARN(!sysfs_ops, KERN_ERR
266 "missing sysfs attribute operations for kobject: %s\n",
267 kobject_name(kobj)))
268 return -EINVAL;
269
270 if (mode & SYSFS_PREALLOC) {
271 if (sysfs_ops->show && sysfs_ops->store)
272 ops = &sysfs_prealloc_kfops_rw;
273 else if (sysfs_ops->show)
274 ops = &sysfs_prealloc_kfops_ro;
275 else if (sysfs_ops->store)
276 ops = &sysfs_prealloc_kfops_wo;
277 } else {
278 if (sysfs_ops->show && sysfs_ops->store)
279 ops = &sysfs_file_kfops_rw;
280 else if (sysfs_ops->show)
281 ops = &sysfs_file_kfops_ro;
282 else if (sysfs_ops->store)
283 ops = &sysfs_file_kfops_wo;
284 }
285
286 if (!ops)
287 ops = &sysfs_file_kfops_empty;
288
289#ifdef CONFIG_DEBUG_LOCK_ALLOC
290 if (!attr->ignore_lockdep)
291 key = attr->key ?: (struct lock_class_key *)&attr->skey;
292#endif
293
294 kn = __kernfs_create_file(parent, attr->name, mode & 0777, uid, gid,
295 PAGE_SIZE, ops, (void *)attr, ns, key);
296 if (IS_ERR(kn)) {
297 if (PTR_ERR(kn) == -EEXIST)
298 sysfs_warn_dup(parent, attr->name);
299 return PTR_ERR(kn);
300 }
301 return 0;
302}
303
304int sysfs_add_bin_file_mode_ns(struct kernfs_node *parent,
305 const struct bin_attribute *battr, umode_t mode,
306 kuid_t uid, kgid_t gid, const void *ns)
307{
308 const struct attribute *attr = &battr->attr;
309 struct lock_class_key *key = NULL;
310 const struct kernfs_ops *ops;
311 struct kernfs_node *kn;
312
313 if (battr->mmap)
314 ops = &sysfs_bin_kfops_mmap;
315 else if (battr->read && battr->write)
316 ops = &sysfs_bin_kfops_rw;
317 else if (battr->read)
318 ops = &sysfs_bin_kfops_ro;
319 else if (battr->write)
320 ops = &sysfs_bin_kfops_wo;
321 else
322 ops = &sysfs_file_kfops_empty;
323
324#ifdef CONFIG_DEBUG_LOCK_ALLOC
325 if (!attr->ignore_lockdep)
326 key = attr->key ?: (struct lock_class_key *)&attr->skey;
327#endif
328
329 kn = __kernfs_create_file(parent, attr->name, mode & 0777, uid, gid,
330 battr->size, ops, (void *)attr, ns, key);
331 if (IS_ERR(kn)) {
332 if (PTR_ERR(kn) == -EEXIST)
333 sysfs_warn_dup(parent, attr->name);
334 return PTR_ERR(kn);
335 }
336 return 0;
337}
338
339/**
340 * sysfs_create_file_ns - create an attribute file for an object with custom ns
341 * @kobj: object we're creating for
342 * @attr: attribute descriptor
343 * @ns: namespace the new file should belong to
344 */
345int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
346 const void *ns)
347{
348 kuid_t uid;
349 kgid_t gid;
350
351 if (WARN_ON(!kobj || !kobj->sd || !attr))
352 return -EINVAL;
353
354 kobject_get_ownership(kobj, &uid, &gid);
355 return sysfs_add_file_mode_ns(kobj->sd, attr, attr->mode, uid, gid, ns);
356}
357EXPORT_SYMBOL_GPL(sysfs_create_file_ns);
358
359int sysfs_create_files(struct kobject *kobj, const struct attribute * const *ptr)
360{
361 int err = 0;
362 int i;
363
364 for (i = 0; ptr[i] && !err; i++)
365 err = sysfs_create_file(kobj, ptr[i]);
366 if (err)
367 while (--i >= 0)
368 sysfs_remove_file(kobj, ptr[i]);
369 return err;
370}
371EXPORT_SYMBOL_GPL(sysfs_create_files);
372
373/**
374 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
375 * @kobj: object we're acting for.
376 * @attr: attribute descriptor.
377 * @group: group name.
378 */
379int sysfs_add_file_to_group(struct kobject *kobj,
380 const struct attribute *attr, const char *group)
381{
382 struct kernfs_node *parent;
383 kuid_t uid;
384 kgid_t gid;
385 int error;
386
387 if (group) {
388 parent = kernfs_find_and_get(kobj->sd, group);
389 } else {
390 parent = kobj->sd;
391 kernfs_get(parent);
392 }
393
394 if (!parent)
395 return -ENOENT;
396
397 kobject_get_ownership(kobj, &uid, &gid);
398 error = sysfs_add_file_mode_ns(parent, attr, attr->mode, uid, gid,
399 NULL);
400 kernfs_put(parent);
401
402 return error;
403}
404EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
405
406/**
407 * sysfs_chmod_file - update the modified mode value on an object attribute.
408 * @kobj: object we're acting for.
409 * @attr: attribute descriptor.
410 * @mode: file permissions.
411 *
412 */
413int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
414 umode_t mode)
415{
416 struct kernfs_node *kn;
417 struct iattr newattrs;
418 int rc;
419
420 kn = kernfs_find_and_get(kobj->sd, attr->name);
421 if (!kn)
422 return -ENOENT;
423
424 newattrs.ia_mode = (mode & S_IALLUGO) | (kn->mode & ~S_IALLUGO);
425 newattrs.ia_valid = ATTR_MODE;
426
427 rc = kernfs_setattr(kn, &newattrs);
428
429 kernfs_put(kn);
430 return rc;
431}
432EXPORT_SYMBOL_GPL(sysfs_chmod_file);
433
434/**
435 * sysfs_break_active_protection - break "active" protection
436 * @kobj: The kernel object @attr is associated with.
437 * @attr: The attribute to break the "active" protection for.
438 *
439 * With sysfs, just like kernfs, deletion of an attribute is postponed until
440 * all active .show() and .store() callbacks have finished unless this function
441 * is called. Hence this function is useful in methods that implement self
442 * deletion.
443 */
444struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
445 const struct attribute *attr)
446{
447 struct kernfs_node *kn;
448
449 kobject_get(kobj);
450 kn = kernfs_find_and_get(kobj->sd, attr->name);
451 if (kn)
452 kernfs_break_active_protection(kn);
453 return kn;
454}
455EXPORT_SYMBOL_GPL(sysfs_break_active_protection);
456
457/**
458 * sysfs_unbreak_active_protection - restore "active" protection
459 * @kn: Pointer returned by sysfs_break_active_protection().
460 *
461 * Undo the effects of sysfs_break_active_protection(). Since this function
462 * calls kernfs_put() on the kernfs node that corresponds to the 'attr'
463 * argument passed to sysfs_break_active_protection() that attribute may have
464 * been removed between the sysfs_break_active_protection() and
465 * sysfs_unbreak_active_protection() calls, it is not safe to access @kn after
466 * this function has returned.
467 */
468void sysfs_unbreak_active_protection(struct kernfs_node *kn)
469{
470 struct kobject *kobj = kn->parent->priv;
471
472 kernfs_unbreak_active_protection(kn);
473 kernfs_put(kn);
474 kobject_put(kobj);
475}
476EXPORT_SYMBOL_GPL(sysfs_unbreak_active_protection);
477
478/**
479 * sysfs_remove_file_ns - remove an object attribute with a custom ns tag
480 * @kobj: object we're acting for
481 * @attr: attribute descriptor
482 * @ns: namespace tag of the file to remove
483 *
484 * Hash the attribute name and namespace tag and kill the victim.
485 */
486void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
487 const void *ns)
488{
489 struct kernfs_node *parent = kobj->sd;
490
491 kernfs_remove_by_name_ns(parent, attr->name, ns);
492}
493EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);
494
495/**
496 * sysfs_remove_file_self - remove an object attribute from its own method
497 * @kobj: object we're acting for
498 * @attr: attribute descriptor
499 *
500 * See kernfs_remove_self() for details.
501 */
502bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr)
503{
504 struct kernfs_node *parent = kobj->sd;
505 struct kernfs_node *kn;
506 bool ret;
507
508 kn = kernfs_find_and_get(parent, attr->name);
509 if (WARN_ON_ONCE(!kn))
510 return false;
511
512 ret = kernfs_remove_self(kn);
513
514 kernfs_put(kn);
515 return ret;
516}
517EXPORT_SYMBOL_GPL(sysfs_remove_file_self);
518
519void sysfs_remove_files(struct kobject *kobj, const struct attribute * const *ptr)
520{
521 int i;
522
523 for (i = 0; ptr[i]; i++)
524 sysfs_remove_file(kobj, ptr[i]);
525}
526EXPORT_SYMBOL_GPL(sysfs_remove_files);
527
528/**
529 * sysfs_remove_file_from_group - remove an attribute file from a group.
530 * @kobj: object we're acting for.
531 * @attr: attribute descriptor.
532 * @group: group name.
533 */
534void sysfs_remove_file_from_group(struct kobject *kobj,
535 const struct attribute *attr, const char *group)
536{
537 struct kernfs_node *parent;
538
539 if (group) {
540 parent = kernfs_find_and_get(kobj->sd, group);
541 } else {
542 parent = kobj->sd;
543 kernfs_get(parent);
544 }
545
546 if (parent) {
547 kernfs_remove_by_name(parent, attr->name);
548 kernfs_put(parent);
549 }
550}
551EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
552
553/**
554 * sysfs_create_bin_file - create binary file for object.
555 * @kobj: object.
556 * @attr: attribute descriptor.
557 */
558int sysfs_create_bin_file(struct kobject *kobj,
559 const struct bin_attribute *attr)
560{
561 kuid_t uid;
562 kgid_t gid;
563
564 if (WARN_ON(!kobj || !kobj->sd || !attr))
565 return -EINVAL;
566
567 kobject_get_ownership(kobj, &uid, &gid);
568 return sysfs_add_bin_file_mode_ns(kobj->sd, attr, attr->attr.mode, uid,
569 gid, NULL);
570}
571EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
572
573/**
574 * sysfs_remove_bin_file - remove binary file for object.
575 * @kobj: object.
576 * @attr: attribute descriptor.
577 */
578void sysfs_remove_bin_file(struct kobject *kobj,
579 const struct bin_attribute *attr)
580{
581 kernfs_remove_by_name(kobj->sd, attr->attr.name);
582}
583EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);
584
585static int internal_change_owner(struct kernfs_node *kn, kuid_t kuid,
586 kgid_t kgid)
587{
588 struct iattr newattrs = {
589 .ia_valid = ATTR_UID | ATTR_GID,
590 .ia_uid = kuid,
591 .ia_gid = kgid,
592 };
593 return kernfs_setattr(kn, &newattrs);
594}
595
596/**
597 * sysfs_link_change_owner - change owner of a sysfs file.
598 * @kobj: object of the kernfs_node the symlink is located in.
599 * @targ: object of the kernfs_node the symlink points to.
600 * @name: name of the link.
601 * @kuid: new owner's kuid
602 * @kgid: new owner's kgid
603 *
604 * This function looks up the sysfs symlink entry @name under @kobj and changes
605 * the ownership to @kuid/@kgid. The symlink is looked up in the namespace of
606 * @targ.
607 *
608 * Returns 0 on success or error code on failure.
609 */
610int sysfs_link_change_owner(struct kobject *kobj, struct kobject *targ,
611 const char *name, kuid_t kuid, kgid_t kgid)
612{
613 struct kernfs_node *kn = NULL;
614 int error;
615
616 if (!name || !kobj->state_in_sysfs || !targ->state_in_sysfs)
617 return -EINVAL;
618
619 error = -ENOENT;
620 kn = kernfs_find_and_get_ns(kobj->sd, name, targ->sd->ns);
621 if (!kn)
622 goto out;
623
624 error = -EINVAL;
625 if (kernfs_type(kn) != KERNFS_LINK)
626 goto out;
627 if (kn->symlink.target_kn->priv != targ)
628 goto out;
629
630 error = internal_change_owner(kn, kuid, kgid);
631
632out:
633 kernfs_put(kn);
634 return error;
635}
636
637/**
638 * sysfs_file_change_owner - change owner of a sysfs file.
639 * @kobj: object.
640 * @name: name of the file to change.
641 * @kuid: new owner's kuid
642 * @kgid: new owner's kgid
643 *
644 * This function looks up the sysfs entry @name under @kobj and changes the
645 * ownership to @kuid/@kgid.
646 *
647 * Returns 0 on success or error code on failure.
648 */
649int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid,
650 kgid_t kgid)
651{
652 struct kernfs_node *kn;
653 int error;
654
655 if (!name)
656 return -EINVAL;
657
658 if (!kobj->state_in_sysfs)
659 return -EINVAL;
660
661 kn = kernfs_find_and_get(kobj->sd, name);
662 if (!kn)
663 return -ENOENT;
664
665 error = internal_change_owner(kn, kuid, kgid);
666
667 kernfs_put(kn);
668
669 return error;
670}
671EXPORT_SYMBOL_GPL(sysfs_file_change_owner);
672
673/**
674 * sysfs_change_owner - change owner of the given object.
675 * @kobj: object.
676 * @kuid: new owner's kuid
677 * @kgid: new owner's kgid
678 *
679 * Change the owner of the default directory, files, groups, and attributes of
680 * @kobj to @kuid/@kgid. Note that sysfs_change_owner mirrors how the sysfs
681 * entries for a kobject are added by driver core. In summary,
682 * sysfs_change_owner() takes care of the default directory entry for @kobj,
683 * the default attributes associated with the ktype of @kobj and the default
684 * attributes associated with the ktype of @kobj.
685 * Additional properties not added by driver core have to be changed by the
686 * driver or subsystem which created them. This is similar to how
687 * driver/subsystem specific entries are removed.
688 *
689 * Returns 0 on success or error code on failure.
690 */
691int sysfs_change_owner(struct kobject *kobj, kuid_t kuid, kgid_t kgid)
692{
693 int error;
694 const struct kobj_type *ktype;
695
696 if (!kobj->state_in_sysfs)
697 return -EINVAL;
698
699 /* Change the owner of the kobject itself. */
700 error = internal_change_owner(kobj->sd, kuid, kgid);
701 if (error)
702 return error;
703
704 ktype = get_ktype(kobj);
705 if (ktype) {
706 /*
707 * Change owner of the default groups associated with the
708 * ktype of @kobj.
709 */
710 error = sysfs_groups_change_owner(kobj, ktype->default_groups,
711 kuid, kgid);
712 if (error)
713 return error;
714 }
715
716 return 0;
717}
718EXPORT_SYMBOL_GPL(sysfs_change_owner);
719
720/**
721 * sysfs_emit - scnprintf equivalent, aware of PAGE_SIZE buffer.
722 * @buf: start of PAGE_SIZE buffer.
723 * @fmt: format
724 * @...: optional arguments to @format
725 *
726 *
727 * Returns number of characters written to @buf.
728 */
729int sysfs_emit(char *buf, const char *fmt, ...)
730{
731 va_list args;
732 int len;
733
734 if (WARN(!buf || offset_in_page(buf),
735 "invalid sysfs_emit: buf:%p\n", buf))
736 return 0;
737
738 va_start(args, fmt);
739 len = vscnprintf(buf, PAGE_SIZE, fmt, args);
740 va_end(args);
741
742 return len;
743}
744EXPORT_SYMBOL_GPL(sysfs_emit);
745
746/**
747 * sysfs_emit_at - scnprintf equivalent, aware of PAGE_SIZE buffer.
748 * @buf: start of PAGE_SIZE buffer.
749 * @at: offset in @buf to start write in bytes
750 * @at must be >= 0 && < PAGE_SIZE
751 * @fmt: format
752 * @...: optional arguments to @fmt
753 *
754 *
755 * Returns number of characters written starting at &@buf[@at].
756 */
757int sysfs_emit_at(char *buf, int at, const char *fmt, ...)
758{
759 va_list args;
760 int len;
761
762 if (WARN(!buf || offset_in_page(buf) || at < 0 || at >= PAGE_SIZE,
763 "invalid sysfs_emit_at: buf:%p at:%d\n", buf, at))
764 return 0;
765
766 va_start(args, fmt);
767 len = vscnprintf(buf + at, PAGE_SIZE - at, fmt, args);
768 va_end(args);
769
770 return len;
771}
772EXPORT_SYMBOL_GPL(sysfs_emit_at);
1/*
2 * fs/sysfs/file.c - sysfs regular (text) file implementation
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
7 *
8 * This file is released under the GPLv2.
9 *
10 * Please see Documentation/filesystems/sysfs.txt for more information.
11 */
12
13#include <linux/module.h>
14#include <linux/kobject.h>
15#include <linux/kallsyms.h>
16#include <linux/slab.h>
17#include <linux/list.h>
18#include <linux/mutex.h>
19#include <linux/seq_file.h>
20
21#include "sysfs.h"
22#include "../kernfs/kernfs-internal.h"
23
24/*
25 * Determine ktype->sysfs_ops for the given kernfs_node. This function
26 * must be called while holding an active reference.
27 */
28static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn)
29{
30 struct kobject *kobj = kn->parent->priv;
31
32 if (kn->flags & KERNFS_LOCKDEP)
33 lockdep_assert_held(kn);
34 return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
35}
36
37/*
38 * Reads on sysfs are handled through seq_file, which takes care of hairy
39 * details like buffering and seeking. The following function pipes
40 * sysfs_ops->show() result through seq_file.
41 */
42static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
43{
44 struct kernfs_open_file *of = sf->private;
45 struct kobject *kobj = of->kn->parent->priv;
46 const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
47 ssize_t count;
48 char *buf;
49
50 /* acquire buffer and ensure that it's >= PAGE_SIZE and clear */
51 count = seq_get_buf(sf, &buf);
52 if (count < PAGE_SIZE) {
53 seq_commit(sf, -1);
54 return 0;
55 }
56 memset(buf, 0, PAGE_SIZE);
57
58 /*
59 * Invoke show(). Control may reach here via seq file lseek even
60 * if @ops->show() isn't implemented.
61 */
62 if (ops->show) {
63 count = ops->show(kobj, of->kn->priv, buf);
64 if (count < 0)
65 return count;
66 }
67
68 /*
69 * The code works fine with PAGE_SIZE return but it's likely to
70 * indicate truncated result or overflow in normal use cases.
71 */
72 if (count >= (ssize_t)PAGE_SIZE) {
73 print_symbol("fill_read_buffer: %s returned bad count\n",
74 (unsigned long)ops->show);
75 /* Try to struggle along */
76 count = PAGE_SIZE - 1;
77 }
78 seq_commit(sf, count);
79 return 0;
80}
81
82static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf,
83 size_t count, loff_t pos)
84{
85 struct bin_attribute *battr = of->kn->priv;
86 struct kobject *kobj = of->kn->parent->priv;
87 loff_t size = file_inode(of->file)->i_size;
88
89 if (!count)
90 return 0;
91
92 if (size) {
93 if (pos > size)
94 return 0;
95 if (pos + count > size)
96 count = size - pos;
97 }
98
99 if (!battr->read)
100 return -EIO;
101
102 return battr->read(of->file, kobj, battr, buf, pos, count);
103}
104
105/* kernfs write callback for regular sysfs files */
106static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf,
107 size_t count, loff_t pos)
108{
109 const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
110 struct kobject *kobj = of->kn->parent->priv;
111
112 if (!count)
113 return 0;
114
115 return ops->store(kobj, of->kn->priv, buf, count);
116}
117
118/* kernfs write callback for bin sysfs files */
119static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf,
120 size_t count, loff_t pos)
121{
122 struct bin_attribute *battr = of->kn->priv;
123 struct kobject *kobj = of->kn->parent->priv;
124 loff_t size = file_inode(of->file)->i_size;
125
126 if (size) {
127 if (size <= pos)
128 return 0;
129 count = min_t(ssize_t, count, size - pos);
130 }
131 if (!count)
132 return 0;
133
134 if (!battr->write)
135 return -EIO;
136
137 return battr->write(of->file, kobj, battr, buf, pos, count);
138}
139
140static int sysfs_kf_bin_mmap(struct kernfs_open_file *of,
141 struct vm_area_struct *vma)
142{
143 struct bin_attribute *battr = of->kn->priv;
144 struct kobject *kobj = of->kn->parent->priv;
145
146 return battr->mmap(of->file, kobj, battr, vma);
147}
148
149void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr)
150{
151 struct kernfs_node *kn = kobj->sd, *tmp;
152
153 if (kn && dir)
154 kn = kernfs_find_and_get(kn, dir);
155 else
156 kernfs_get(kn);
157
158 if (kn && attr) {
159 tmp = kernfs_find_and_get(kn, attr);
160 kernfs_put(kn);
161 kn = tmp;
162 }
163
164 if (kn) {
165 kernfs_notify(kn);
166 kernfs_put(kn);
167 }
168}
169EXPORT_SYMBOL_GPL(sysfs_notify);
170
171static const struct kernfs_ops sysfs_file_kfops_empty = {
172};
173
174static const struct kernfs_ops sysfs_file_kfops_ro = {
175 .seq_show = sysfs_kf_seq_show,
176};
177
178static const struct kernfs_ops sysfs_file_kfops_wo = {
179 .write = sysfs_kf_write,
180};
181
182static const struct kernfs_ops sysfs_file_kfops_rw = {
183 .seq_show = sysfs_kf_seq_show,
184 .write = sysfs_kf_write,
185};
186
187static const struct kernfs_ops sysfs_bin_kfops_ro = {
188 .read = sysfs_kf_bin_read,
189};
190
191static const struct kernfs_ops sysfs_bin_kfops_wo = {
192 .write = sysfs_kf_bin_write,
193};
194
195static const struct kernfs_ops sysfs_bin_kfops_rw = {
196 .read = sysfs_kf_bin_read,
197 .write = sysfs_kf_bin_write,
198};
199
200static const struct kernfs_ops sysfs_bin_kfops_mmap = {
201 .read = sysfs_kf_bin_read,
202 .write = sysfs_kf_bin_write,
203 .mmap = sysfs_kf_bin_mmap,
204};
205
206int sysfs_add_file_mode_ns(struct kernfs_node *parent,
207 const struct attribute *attr, bool is_bin,
208 umode_t mode, const void *ns)
209{
210 struct lock_class_key *key = NULL;
211 const struct kernfs_ops *ops;
212 struct kernfs_node *kn;
213 loff_t size;
214
215 if (!is_bin) {
216 struct kobject *kobj = parent->priv;
217 const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
218
219 /* every kobject with an attribute needs a ktype assigned */
220 if (WARN(!sysfs_ops, KERN_ERR
221 "missing sysfs attribute operations for kobject: %s\n",
222 kobject_name(kobj)))
223 return -EINVAL;
224
225 if (sysfs_ops->show && sysfs_ops->store)
226 ops = &sysfs_file_kfops_rw;
227 else if (sysfs_ops->show)
228 ops = &sysfs_file_kfops_ro;
229 else if (sysfs_ops->store)
230 ops = &sysfs_file_kfops_wo;
231 else
232 ops = &sysfs_file_kfops_empty;
233
234 size = PAGE_SIZE;
235 } else {
236 struct bin_attribute *battr = (void *)attr;
237
238 if (battr->mmap)
239 ops = &sysfs_bin_kfops_mmap;
240 else if (battr->read && battr->write)
241 ops = &sysfs_bin_kfops_rw;
242 else if (battr->read)
243 ops = &sysfs_bin_kfops_ro;
244 else if (battr->write)
245 ops = &sysfs_bin_kfops_wo;
246 else
247 ops = &sysfs_file_kfops_empty;
248
249 size = battr->size;
250 }
251
252#ifdef CONFIG_DEBUG_LOCK_ALLOC
253 if (!attr->ignore_lockdep)
254 key = attr->key ?: (struct lock_class_key *)&attr->skey;
255#endif
256 kn = __kernfs_create_file(parent, attr->name, mode, size, ops,
257 (void *)attr, ns, true, key);
258 if (IS_ERR(kn)) {
259 if (PTR_ERR(kn) == -EEXIST)
260 sysfs_warn_dup(parent, attr->name);
261 return PTR_ERR(kn);
262 }
263 return 0;
264}
265
266int sysfs_add_file(struct kernfs_node *parent, const struct attribute *attr,
267 bool is_bin)
268{
269 return sysfs_add_file_mode_ns(parent, attr, is_bin, attr->mode, NULL);
270}
271
272/**
273 * sysfs_create_file_ns - create an attribute file for an object with custom ns
274 * @kobj: object we're creating for
275 * @attr: attribute descriptor
276 * @ns: namespace the new file should belong to
277 */
278int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
279 const void *ns)
280{
281 BUG_ON(!kobj || !kobj->sd || !attr);
282
283 return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns);
284
285}
286EXPORT_SYMBOL_GPL(sysfs_create_file_ns);
287
288int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
289{
290 int err = 0;
291 int i;
292
293 for (i = 0; ptr[i] && !err; i++)
294 err = sysfs_create_file(kobj, ptr[i]);
295 if (err)
296 while (--i >= 0)
297 sysfs_remove_file(kobj, ptr[i]);
298 return err;
299}
300EXPORT_SYMBOL_GPL(sysfs_create_files);
301
302/**
303 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
304 * @kobj: object we're acting for.
305 * @attr: attribute descriptor.
306 * @group: group name.
307 */
308int sysfs_add_file_to_group(struct kobject *kobj,
309 const struct attribute *attr, const char *group)
310{
311 struct kernfs_node *parent;
312 int error;
313
314 if (group) {
315 parent = kernfs_find_and_get(kobj->sd, group);
316 } else {
317 parent = kobj->sd;
318 kernfs_get(parent);
319 }
320
321 if (!parent)
322 return -ENOENT;
323
324 error = sysfs_add_file(parent, attr, false);
325 kernfs_put(parent);
326
327 return error;
328}
329EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
330
331/**
332 * sysfs_chmod_file - update the modified mode value on an object attribute.
333 * @kobj: object we're acting for.
334 * @attr: attribute descriptor.
335 * @mode: file permissions.
336 *
337 */
338int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
339 umode_t mode)
340{
341 struct kernfs_node *kn;
342 struct iattr newattrs;
343 int rc;
344
345 kn = kernfs_find_and_get(kobj->sd, attr->name);
346 if (!kn)
347 return -ENOENT;
348
349 newattrs.ia_mode = (mode & S_IALLUGO) | (kn->mode & ~S_IALLUGO);
350 newattrs.ia_valid = ATTR_MODE;
351
352 rc = kernfs_setattr(kn, &newattrs);
353
354 kernfs_put(kn);
355 return rc;
356}
357EXPORT_SYMBOL_GPL(sysfs_chmod_file);
358
359/**
360 * sysfs_remove_file_ns - remove an object attribute with a custom ns tag
361 * @kobj: object we're acting for
362 * @attr: attribute descriptor
363 * @ns: namespace tag of the file to remove
364 *
365 * Hash the attribute name and namespace tag and kill the victim.
366 */
367void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
368 const void *ns)
369{
370 struct kernfs_node *parent = kobj->sd;
371
372 kernfs_remove_by_name_ns(parent, attr->name, ns);
373}
374EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);
375
376/**
377 * sysfs_remove_file_self - remove an object attribute from its own method
378 * @kobj: object we're acting for
379 * @attr: attribute descriptor
380 *
381 * See kernfs_remove_self() for details.
382 */
383bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr)
384{
385 struct kernfs_node *parent = kobj->sd;
386 struct kernfs_node *kn;
387 bool ret;
388
389 kn = kernfs_find_and_get(parent, attr->name);
390 if (WARN_ON_ONCE(!kn))
391 return false;
392
393 ret = kernfs_remove_self(kn);
394
395 kernfs_put(kn);
396 return ret;
397}
398
399void sysfs_remove_files(struct kobject *kobj, const struct attribute **ptr)
400{
401 int i;
402 for (i = 0; ptr[i]; i++)
403 sysfs_remove_file(kobj, ptr[i]);
404}
405EXPORT_SYMBOL_GPL(sysfs_remove_files);
406
407/**
408 * sysfs_remove_file_from_group - remove an attribute file from a group.
409 * @kobj: object we're acting for.
410 * @attr: attribute descriptor.
411 * @group: group name.
412 */
413void sysfs_remove_file_from_group(struct kobject *kobj,
414 const struct attribute *attr, const char *group)
415{
416 struct kernfs_node *parent;
417
418 if (group) {
419 parent = kernfs_find_and_get(kobj->sd, group);
420 } else {
421 parent = kobj->sd;
422 kernfs_get(parent);
423 }
424
425 if (parent) {
426 kernfs_remove_by_name(parent, attr->name);
427 kernfs_put(parent);
428 }
429}
430EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
431
432/**
433 * sysfs_create_bin_file - create binary file for object.
434 * @kobj: object.
435 * @attr: attribute descriptor.
436 */
437int sysfs_create_bin_file(struct kobject *kobj,
438 const struct bin_attribute *attr)
439{
440 BUG_ON(!kobj || !kobj->sd || !attr);
441
442 return sysfs_add_file(kobj->sd, &attr->attr, true);
443}
444EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
445
446/**
447 * sysfs_remove_bin_file - remove binary file for object.
448 * @kobj: object.
449 * @attr: attribute descriptor.
450 */
451void sysfs_remove_bin_file(struct kobject *kobj,
452 const struct bin_attribute *attr)
453{
454 kernfs_remove_by_name(kobj->sd, attr->attr.name);
455}
456EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);