xref: /openbmc/linux/fs/sysfs/group.c (revision 1c2dd16a)
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 
21 static 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 
35 static 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 	}
102 exit:
103 	return error;
104 }
105 
106 
107 static 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  */
153 int sysfs_create_group(struct kobject *kobj,
154 		       const struct attribute_group *grp)
155 {
156 	return internal_create_group(kobj, 0, grp);
157 }
158 EXPORT_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  */
173 int 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 }
192 EXPORT_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  */
211 int sysfs_update_group(struct kobject *kobj,
212 		       const struct attribute_group *grp)
213 {
214 	return internal_create_group(kobj, 1, grp);
215 }
216 EXPORT_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  */
226 void 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 '%s' not found for kobject '%s'\n",
237 			     grp->name, 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 }
251 EXPORT_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  */
261 void 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 }
271 EXPORT_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  */
282 int 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 }
304 EXPORT_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  */
311 void 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 }
324 EXPORT_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  */
333 int 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 }
348 EXPORT_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  */
356 void 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 }
367 EXPORT_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  */
376 int __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 }
411 EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
412