1/*
2 * fs/sysfs/group.c - Operations for adding/removing multiple files at once.
3 *
4 * Copyright (c) 2003 Patrick Mochel
5 * Copyright (c) 2003 Open Source Development Lab
6 * Copyright (c) 2013 Greg Kroah-Hartman
7 * Copyright (c) 2013 The Linux Foundation
8 *
9 * This file is released undert the GPL v2.
10 *
11 */
12
13#include <linux/kobject.h>
14#include <linux/module.h>
15#include <linux/dcache.h>
16#include <linux/namei.h>
17#include <linux/err.h>
18#include "sysfs.h"
19
20
21static void remove_files(struct kernfs_node *parent,
22			 const struct attribute_group *grp)
23{
24	struct attribute *const *attr;
25	struct bin_attribute *const *bin_attr;
26
27	if (grp->attrs)
28		for (attr = grp->attrs; *attr; attr++)
29			kernfs_remove_by_name(parent, (*attr)->name);
30	if (grp->bin_attrs)
31		for (bin_attr = grp->bin_attrs; *bin_attr; bin_attr++)
32			kernfs_remove_by_name(parent, (*bin_attr)->attr.name);
33}
34
35static int create_files(struct kernfs_node *parent, struct kobject *kobj,
36			const struct attribute_group *grp, int update)
37{
38	struct attribute *const *attr;
39	struct bin_attribute *const *bin_attr;
40	int error = 0, i;
41
42	if (grp->attrs) {
43		for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {
44			umode_t mode = (*attr)->mode;
45
46			/*
47			 * In update mode, we're changing the permissions or
48			 * visibility.  Do this by first removing then
49			 * re-adding (if required) the file.
50			 */
51			if (update)
52				kernfs_remove_by_name(parent, (*attr)->name);
53			if (grp->is_visible) {
54				mode = grp->is_visible(kobj, *attr, i);
55				if (!mode)
56					continue;
57			}
58
59			WARN(mode & ~(SYSFS_PREALLOC | 0664),
60			     "Attribute %s: Invalid permissions 0%o\n",
61			     (*attr)->name, mode);
62
63			mode &= SYSFS_PREALLOC | 0664;
64			error = sysfs_add_file_mode_ns(parent, *attr, false,
65						       mode, NULL);
66			if (unlikely(error))
67				break;
68		}
69		if (error) {
70			remove_files(parent, grp);
71			goto exit;
72		}
73	}
74
75	if (grp->bin_attrs) {
76		for (i = 0, bin_attr = grp->bin_attrs; *bin_attr; i++, bin_attr++) {
77			umode_t mode = (*bin_attr)->attr.mode;
78
79			if (update)
80				kernfs_remove_by_name(parent,
81						(*bin_attr)->attr.name);
82			if (grp->is_bin_visible) {
83				mode = grp->is_bin_visible(kobj, *bin_attr, i);
84				if (!mode)
85					continue;
86			}
87
88			WARN(mode & ~(SYSFS_PREALLOC | 0664),
89			     "Attribute %s: Invalid permissions 0%o\n",
90			     (*bin_attr)->attr.name, mode);
91
92			mode &= SYSFS_PREALLOC | 0664;
93			error = sysfs_add_file_mode_ns(parent,
94					&(*bin_attr)->attr, true,
95					mode, NULL);
96			if (error)
97				break;
98		}
99		if (error)
100			remove_files(parent, grp);
101	}
102exit:
103	return error;
104}
105
106
107static int internal_create_group(struct kobject *kobj, int update,
108				 const struct attribute_group *grp)
109{
110	struct kernfs_node *kn;
111	int error;
112
113	BUG_ON(!kobj || (!update && !kobj->sd));
114
115	/* Updates may happen before the object has been instantiated */
116	if (unlikely(update && !kobj->sd))
117		return -EINVAL;
118	if (!grp->attrs && !grp->bin_attrs) {
119		WARN(1, "sysfs: (bin_)attrs not set by subsystem for group: %s/%s\n",
120			kobj->name, grp->name ?: "");
121		return -EINVAL;
122	}
123	if (grp->name) {
124		kn = kernfs_create_dir(kobj->sd, grp->name,
125				       S_IRWXU | S_IRUGO | S_IXUGO, kobj);
126		if (IS_ERR(kn)) {
127			if (PTR_ERR(kn) == -EEXIST)
128				sysfs_warn_dup(kobj->sd, grp->name);
129			return PTR_ERR(kn);
130		}
131	} else
132		kn = kobj->sd;
133	kernfs_get(kn);
134	error = create_files(kn, kobj, grp, update);
135	if (error) {
136		if (grp->name)
137			kernfs_remove(kn);
138	}
139	kernfs_put(kn);
140	return error;
141}
142
143/**
144 * sysfs_create_group - given a directory kobject, create an attribute group
145 * @kobj:	The kobject to create the group on
146 * @grp:	The attribute group to create
147 *
148 * This function creates a group for the first time.  It will explicitly
149 * warn and error if any of the attribute files being created already exist.
150 *
151 * Returns 0 on success or error code on failure.
152 */
153int sysfs_create_group(struct kobject *kobj,
154		       const struct attribute_group *grp)
155{
156	return internal_create_group(kobj, 0, grp);
157}
158EXPORT_SYMBOL_GPL(sysfs_create_group);
159
160/**
161 * sysfs_create_groups - given a directory kobject, create a bunch of attribute groups
162 * @kobj:	The kobject to create the group on
163 * @groups:	The attribute groups to create, NULL terminated
164 *
165 * This function creates a bunch of attribute groups.  If an error occurs when
166 * creating a group, all previously created groups will be removed, unwinding
167 * everything back to the original state when this function was called.
168 * It will explicitly warn and error if any of the attribute files being
169 * created already exist.
170 *
171 * Returns 0 on success or error code from sysfs_create_group on failure.
172 */
173int sysfs_create_groups(struct kobject *kobj,
174			const struct attribute_group **groups)
175{
176	int error = 0;
177	int i;
178
179	if (!groups)
180		return 0;
181
182	for (i = 0; groups[i]; i++) {
183		error = sysfs_create_group(kobj, groups[i]);
184		if (error) {
185			while (--i >= 0)
186				sysfs_remove_group(kobj, groups[i]);
187			break;
188		}
189	}
190	return error;
191}
192EXPORT_SYMBOL_GPL(sysfs_create_groups);
193
194/**
195 * sysfs_update_group - given a directory kobject, update an attribute group
196 * @kobj:	The kobject to update the group on
197 * @grp:	The attribute group to update
198 *
199 * This function updates an attribute group.  Unlike
200 * sysfs_create_group(), it will explicitly not warn or error if any
201 * of the attribute files being created already exist.  Furthermore,
202 * if the visibility of the files has changed through the is_visible()
203 * callback, it will update the permissions and add or remove the
204 * relevant files.
205 *
206 * The primary use for this function is to call it after making a change
207 * that affects group visibility.
208 *
209 * Returns 0 on success or error code on failure.
210 */
211int sysfs_update_group(struct kobject *kobj,
212		       const struct attribute_group *grp)
213{
214	return internal_create_group(kobj, 1, grp);
215}
216EXPORT_SYMBOL_GPL(sysfs_update_group);
217
218/**
219 * sysfs_remove_group: remove a group from a kobject
220 * @kobj:	kobject to remove the group from
221 * @grp:	group to remove
222 *
223 * This function removes a group of attributes from a kobject.  The attributes
224 * previously have to have been created for this group, otherwise it will fail.
225 */
226void sysfs_remove_group(struct kobject *kobj,
227			const struct attribute_group *grp)
228{
229	struct kernfs_node *parent = kobj->sd;
230	struct kernfs_node *kn;
231
232	if (grp->name) {
233		kn = kernfs_find_and_get(parent, grp->name);
234		if (!kn) {
235			WARN(!kn, KERN_WARNING
236			     "sysfs group %p not found for kobject '%s'\n",
237			     grp, kobject_name(kobj));
238			return;
239		}
240	} else {
241		kn = parent;
242		kernfs_get(kn);
243	}
244
245	remove_files(kn, grp);
246	if (grp->name)
247		kernfs_remove(kn);
248
249	kernfs_put(kn);
250}
251EXPORT_SYMBOL_GPL(sysfs_remove_group);
252
253/**
254 * sysfs_remove_groups - remove a list of groups
255 *
256 * @kobj:	The kobject for the groups to be removed from
257 * @groups:	NULL terminated list of groups to be removed
258 *
259 * If groups is not NULL, remove the specified groups from the kobject.
260 */
261void sysfs_remove_groups(struct kobject *kobj,
262			 const struct attribute_group **groups)
263{
264	int i;
265
266	if (!groups)
267		return;
268	for (i = 0; groups[i]; i++)
269		sysfs_remove_group(kobj, groups[i]);
270}
271EXPORT_SYMBOL_GPL(sysfs_remove_groups);
272
273/**
274 * sysfs_merge_group - merge files into a pre-existing attribute group.
275 * @kobj:	The kobject containing the group.
276 * @grp:	The files to create and the attribute group they belong to.
277 *
278 * This function returns an error if the group doesn't exist or any of the
279 * files already exist in that group, in which case none of the new files
280 * are created.
281 */
282int sysfs_merge_group(struct kobject *kobj,
283		       const struct attribute_group *grp)
284{
285	struct kernfs_node *parent;
286	int error = 0;
287	struct attribute *const *attr;
288	int i;
289
290	parent = kernfs_find_and_get(kobj->sd, grp->name);
291	if (!parent)
292		return -ENOENT;
293
294	for ((i = 0, attr = grp->attrs); *attr && !error; (++i, ++attr))
295		error = sysfs_add_file(parent, *attr, false);
296	if (error) {
297		while (--i >= 0)
298			kernfs_remove_by_name(parent, (*--attr)->name);
299	}
300	kernfs_put(parent);
301
302	return error;
303}
304EXPORT_SYMBOL_GPL(sysfs_merge_group);
305
306/**
307 * sysfs_unmerge_group - remove files from a pre-existing attribute group.
308 * @kobj:	The kobject containing the group.
309 * @grp:	The files to remove and the attribute group they belong to.
310 */
311void sysfs_unmerge_group(struct kobject *kobj,
312		       const struct attribute_group *grp)
313{
314	struct kernfs_node *parent;
315	struct attribute *const *attr;
316
317	parent = kernfs_find_and_get(kobj->sd, grp->name);
318	if (parent) {
319		for (attr = grp->attrs; *attr; ++attr)
320			kernfs_remove_by_name(parent, (*attr)->name);
321		kernfs_put(parent);
322	}
323}
324EXPORT_SYMBOL_GPL(sysfs_unmerge_group);
325
326/**
327 * sysfs_add_link_to_group - add a symlink to an attribute group.
328 * @kobj:	The kobject containing the group.
329 * @group_name:	The name of the group.
330 * @target:	The target kobject of the symlink to create.
331 * @link_name:	The name of the symlink to create.
332 */
333int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
334			    struct kobject *target, const char *link_name)
335{
336	struct kernfs_node *parent;
337	int error = 0;
338
339	parent = kernfs_find_and_get(kobj->sd, group_name);
340	if (!parent)
341		return -ENOENT;
342
343	error = sysfs_create_link_sd(parent, target, link_name);
344	kernfs_put(parent);
345
346	return error;
347}
348EXPORT_SYMBOL_GPL(sysfs_add_link_to_group);
349
350/**
351 * sysfs_remove_link_from_group - remove a symlink from an attribute group.
352 * @kobj:	The kobject containing the group.
353 * @group_name:	The name of the group.
354 * @link_name:	The name of the symlink to remove.
355 */
356void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
357				  const char *link_name)
358{
359	struct kernfs_node *parent;
360
361	parent = kernfs_find_and_get(kobj->sd, group_name);
362	if (parent) {
363		kernfs_remove_by_name(parent, link_name);
364		kernfs_put(parent);
365	}
366}
367EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
368
369/**
370 * __compat_only_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing
371 * to a group or an attribute
372 * @kobj:		The kobject containing the group.
373 * @target_kobj:	The target kobject.
374 * @target_name:	The name of the target group or attribute.
375 */
376int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
377				      struct kobject *target_kobj,
378				      const char *target_name)
379{
380	struct kernfs_node *target;
381	struct kernfs_node *entry;
382	struct kernfs_node *link;
383
384	/*
385	 * We don't own @target_kobj and it may be removed at any time.
386	 * Synchronize using sysfs_symlink_target_lock. See sysfs_remove_dir()
387	 * for details.
388	 */
389	spin_lock(&sysfs_symlink_target_lock);
390	target = target_kobj->sd;
391	if (target)
392		kernfs_get(target);
393	spin_unlock(&sysfs_symlink_target_lock);
394	if (!target)
395		return -ENOENT;
396
397	entry = kernfs_find_and_get(target_kobj->sd, target_name);
398	if (!entry) {
399		kernfs_put(target);
400		return -ENOENT;
401	}
402
403	link = kernfs_create_link(kobj->sd, target_name, entry);
404	if (IS_ERR(link) && PTR_ERR(link) == -EEXIST)
405		sysfs_warn_dup(kobj->sd, target_name);
406
407	kernfs_put(entry);
408	kernfs_put(target);
409	return IS_ERR(link) ? PTR_ERR(link) : 0;
410}
411EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
412