fs/sysfs/group.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * fs/sysfs/group.c - Operations for adding/removing multiple files at once.
   4  *
   5  * Copyright (c) 2003 Patrick Mochel
   6  * Copyright (c) 2003 Open Source Development Lab
   7  * Copyright (c) 2013 Greg Kroah-Hartman
   8  * Copyright (c) 2013 The Linux Foundation
   9  */
  10
  11 #include <linux/kobject.h>
  12 #include <linux/module.h>
  13 #include <linux/dcache.h>
  14 #include <linux/namei.h>
  15 #include <linux/err.h>
  16 #include "sysfs.h"
  17
  18
  19 static void remove_files(struct kernfs_node *parent,
  20                          const struct attribute_group *grp)
  21 {
  22         struct attribute *const *attr;
  23         struct bin_attribute *const *bin_attr;
  24
  25         if (grp->attrs)
  26                 for (attr = grp->attrs; *attr; attr++)
  27                         kernfs_remove_by_name(parent, (*attr)->name);
  28         if (grp->bin_attrs)
  29                 for (bin_attr = grp->bin_attrs; *bin_attr; bin_attr++)
  30                         kernfs_remove_by_name(parent, (*bin_attr)->attr.name);
  31 }
  32
  33 static int create_files(struct kernfs_node *parent, struct kobject *kobj,
  34                         kuid_t uid, kgid_t gid,
  35                         const struct attribute_group *grp, int update)
  36 {
  37         struct attribute *const *attr;
  38         struct bin_attribute *const *bin_attr;
  39         int error = 0, i;
  40
  41         if (grp->attrs) {
  42                 for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {
  43                         umode_t mode = (*attr)->mode;
  44
  45                         /*
  46                          * In update mode, we're changing the permissions or
  47                          * visibility.  Do this by first removing then
  48                          * re-adding (if required) the file.
  49                          */
  50                         if (update)
  51                                 kernfs_remove_by_name(parent, (*attr)->name);
  52                         if (grp->is_visible) {
  53                                 mode = grp->is_visible(kobj, *attr, i);
  54                                 if (!mode)
  55                                         continue;
  56                         }
  57
  58                         WARN(mode & ~(SYSFS_PREALLOC | 0664),
  59                              "Attribute %s: Invalid permissions 0%o\n",
  60                              (*attr)->name, mode);
  61
  62                         mode &= SYSFS_PREALLOC | 0664;
  63                         error = sysfs_add_file_mode_ns(parent, *attr, false,
  64                                                        mode, uid, gid, NULL);
  65                         if (unlikely(error))
  66                                 break;
  67                 }
  68                 if (error) {
  69                         remove_files(parent, grp);
  70                         goto exit;
  71                 }
  72         }
  73
  74         if (grp->bin_attrs) {
  75                 for (i = 0, bin_attr = grp->bin_attrs; *bin_attr; i++, bin_attr++) {
  76                         umode_t mode = (*bin_attr)->attr.mode;
  77
  78                         if (update)
  79                                 kernfs_remove_by_name(parent,
  80                                                 (*bin_attr)->attr.name);
  81                         if (grp->is_bin_visible) {
  82                                 mode = grp->is_bin_visible(kobj, *bin_attr, i);
  83                                 if (!mode)
  84                                         continue;
  85                         }
  86
  87                         WARN(mode & ~(SYSFS_PREALLOC | 0664),
  88                              "Attribute %s: Invalid permissions 0%o\n",
  89                              (*bin_attr)->attr.name, mode);
  90
  91                         mode &= SYSFS_PREALLOC | 0664;
  92                         error = sysfs_add_file_mode_ns(parent,
  93                                         &(*bin_attr)->attr, true,
  94                                         mode,
  95                                         uid, gid, 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         kuid_t uid;
 112         kgid_t gid;
 113         int error;
 114
 115         if (WARN_ON(!kobj || (!update && !kobj->sd)))
 116                 return -EINVAL;
 117
 118         /* Updates may happen before the object has been instantiated */
 119         if (unlikely(update && !kobj->sd))
 120                 return -EINVAL;
 121         if (!grp->attrs && !grp->bin_attrs) {
 122                 WARN(1, "sysfs: (bin_)attrs not set by subsystem for group: %s/%s\n",
 123                         kobj->name, grp->name ?: "");
 124                 return -EINVAL;
 125         }
 126         kobject_get_ownership(kobj, &uid, &gid);
 127         if (grp->name) {
 128                 if (update) {
 129                         kn = kernfs_find_and_get(kobj->sd, grp->name);
 130                         if (!kn) {
 131                                 pr_warn("Can't update unknown attr grp name: %s/%s\n",
 132                                         kobj->name, grp->name);
 133                                 return -EINVAL;
 134                         }
 135                 } else {
 136                         kn = kernfs_create_dir_ns(kobj->sd, grp->name,
 137                                                   S_IRWXU | S_IRUGO | S_IXUGO,
 138                                                   uid, gid, kobj, NULL);
 139                         if (IS_ERR(kn)) {
 140                                 if (PTR_ERR(kn) == -EEXIST)
 141                                         sysfs_warn_dup(kobj->sd, grp->name);
 142                                 return PTR_ERR(kn);
 143                         }
 144                 }
 145         } else
 146                 kn = kobj->sd;
 147         kernfs_get(kn);
 148         error = create_files(kn, kobj, uid, gid, grp, update);
 149         if (error) {
 150                 if (grp->name)
 151                         kernfs_remove(kn);
 152         }
 153         kernfs_put(kn);
 154
 155         if (grp->name && update)
 156                 kernfs_put(kn);
 157
 158         return error;
 159 }
 160
 161 /**
 162  * sysfs_create_group - given a directory kobject, create an attribute group
 163  * @kobj:       The kobject to create the group on
 164  * @grp:        The attribute group to create
 165  *
 166  * This function creates a group for the first time.  It will explicitly
 167  * warn and error if any of the attribute files being created already exist.
 168  *
 169  * Returns 0 on success or error code on failure.
 170  */
 171 int sysfs_create_group(struct kobject *kobj,
 172                        const struct attribute_group *grp)
 173 {
 174         return internal_create_group(kobj, 0, grp);
 175 }
 176 EXPORT_SYMBOL_GPL(sysfs_create_group);
 177
 178 /**
 179  * sysfs_create_groups - given a directory kobject, create a bunch of attribute groups
 180  * @kobj:       The kobject to create the group on
 181  * @groups:     The attribute groups to create, NULL terminated
 182  *
 183  * This function creates a bunch of attribute groups.  If an error occurs when
 184  * creating a group, all previously created groups will be removed, unwinding
 185  * everything back to the original state when this function was called.
 186  * It will explicitly warn and error if any of the attribute files being
 187  * created already exist.
 188  *
 189  * Returns 0 on success or error code from sysfs_create_group on failure.
 190  */
 191 int sysfs_create_groups(struct kobject *kobj,
 192                         const struct attribute_group **groups)
 193 {
 194         int error = 0;
 195         int i;
 196
 197         if (!groups)
 198                 return 0;
 199
 200         for (i = 0; groups[i]; i++) {
 201                 error = sysfs_create_group(kobj, groups[i]);
 202                 if (error) {
 203                         while (--i >= 0)
 204                                 sysfs_remove_group(kobj, groups[i]);
 205                         break;
 206                 }
 207         }
 208         return error;
 209 }
 210 EXPORT_SYMBOL_GPL(sysfs_create_groups);
 211
 212 /**
 213  * sysfs_update_group - given a directory kobject, update an attribute group
 214  * @kobj:       The kobject to update the group on
 215  * @grp:        The attribute group to update
 216  *
 217  * This function updates an attribute group.  Unlike
 218  * sysfs_create_group(), it will explicitly not warn or error if any
 219  * of the attribute files being created already exist.  Furthermore,
 220  * if the visibility of the files has changed through the is_visible()
 221  * callback, it will update the permissions and add or remove the
 222  * relevant files. Changing a group's name (subdirectory name under
 223  * kobj's directory in sysfs) is not allowed.
 224  *
 225  * The primary use for this function is to call it after making a change
 226  * that affects group visibility.
 227  *
 228  * Returns 0 on success or error code on failure.
 229  */
 230 int sysfs_update_group(struct kobject *kobj,
 231                        const struct attribute_group *grp)
 232 {
 233         return internal_create_group(kobj, 1, grp);
 234 }
 235 EXPORT_SYMBOL_GPL(sysfs_update_group);
 236
 237 /**
 238  * sysfs_remove_group: remove a group from a kobject
 239  * @kobj:       kobject to remove the group from
 240  * @grp:        group to remove
 241  *
 242  * This function removes a group of attributes from a kobject.  The attributes
 243  * previously have to have been created for this group, otherwise it will fail.
 244  */
 245 void sysfs_remove_group(struct kobject *kobj,
 246                         const struct attribute_group *grp)
 247 {
 248         struct kernfs_node *parent = kobj->sd;
 249         struct kernfs_node *kn;
 250
 251         if (grp->name) {
 252                 kn = kernfs_find_and_get(parent, grp->name);
 253                 if (!kn) {
 254                         WARN(!kn, KERN_WARNING
 255                              "sysfs group '%s' not found for kobject '%s'\n",
 256                              grp->name, kobject_name(kobj));
 257                         return;
 258                 }
 259         } else {
 260                 kn = parent;
 261                 kernfs_get(kn);
 262         }
 263
 264         remove_files(kn, grp);
 265         if (grp->name)
 266                 kernfs_remove(kn);
 267
 268         kernfs_put(kn);
 269 }
 270 EXPORT_SYMBOL_GPL(sysfs_remove_group);
 271
 272 /**
 273  * sysfs_remove_groups - remove a list of groups
 274  *
 275  * @kobj:       The kobject for the groups to be removed from
 276  * @groups:     NULL terminated list of groups to be removed
 277  *
 278  * If groups is not NULL, remove the specified groups from the kobject.
 279  */
 280 void sysfs_remove_groups(struct kobject *kobj,
 281                          const struct attribute_group **groups)
 282 {
 283         int i;
 284
 285         if (!groups)
 286                 return;
 287         for (i = 0; groups[i]; i++)
 288                 sysfs_remove_group(kobj, groups[i]);
 289 }
 290 EXPORT_SYMBOL_GPL(sysfs_remove_groups);
 291
 292 /**
 293  * sysfs_merge_group - merge files into a pre-existing attribute group.
 294  * @kobj:       The kobject containing the group.
 295  * @grp:        The files to create and the attribute group they belong to.
 296  *
 297  * This function returns an error if the group doesn't exist or any of the
 298  * files already exist in that group, in which case none of the new files
 299  * are created.
 300  */
 301 int sysfs_merge_group(struct kobject *kobj,
 302                        const struct attribute_group *grp)
 303 {
 304         struct kernfs_node *parent;
 305         kuid_t uid;
 306         kgid_t gid;
 307         int error = 0;
 308         struct attribute *const *attr;
 309         int i;
 310
 311         parent = kernfs_find_and_get(kobj->sd, grp->name);
 312         if (!parent)
 313                 return -ENOENT;
 314
 315         kobject_get_ownership(kobj, &uid, &gid);
 316
 317         for ((i = 0, attr = grp->attrs); *attr && !error; (++i, ++attr))
 318                 error = sysfs_add_file_mode_ns(parent, *attr, false,
 319                                                (*attr)->mode, uid, gid, NULL);
 320         if (error) {
 321                 while (--i >= 0)
 322                         kernfs_remove_by_name(parent, (*--attr)->name);
 323         }
 324         kernfs_put(parent);
 325
 326         return error;
 327 }
 328 EXPORT_SYMBOL_GPL(sysfs_merge_group);
 329
 330 /**
 331  * sysfs_unmerge_group - remove files from a pre-existing attribute group.
 332  * @kobj:       The kobject containing the group.
 333  * @grp:        The files to remove and the attribute group they belong to.
 334  */
 335 void sysfs_unmerge_group(struct kobject *kobj,
 336                        const struct attribute_group *grp)
 337 {
 338         struct kernfs_node *parent;
 339         struct attribute *const *attr;
 340
 341         parent = kernfs_find_and_get(kobj->sd, grp->name);
 342         if (parent) {
 343                 for (attr = grp->attrs; *attr; ++attr)
 344                         kernfs_remove_by_name(parent, (*attr)->name);
 345                 kernfs_put(parent);
 346         }
 347 }
 348 EXPORT_SYMBOL_GPL(sysfs_unmerge_group);
 349
 350 /**
 351  * sysfs_add_link_to_group - add a symlink to an attribute group.
 352  * @kobj:       The kobject containing the group.
 353  * @group_name: The name of the group.
 354  * @target:     The target kobject of the symlink to create.
 355  * @link_name:  The name of the symlink to create.
 356  */
 357 int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
 358                             struct kobject *target, const char *link_name)
 359 {
 360         struct kernfs_node *parent;
 361         int error = 0;
 362
 363         parent = kernfs_find_and_get(kobj->sd, group_name);
 364         if (!parent)
 365                 return -ENOENT;
 366
 367         error = sysfs_create_link_sd(parent, target, link_name);
 368         kernfs_put(parent);
 369
 370         return error;
 371 }
 372 EXPORT_SYMBOL_GPL(sysfs_add_link_to_group);
 373
 374 /**
 375  * sysfs_remove_link_from_group - remove a symlink from an attribute group.
 376  * @kobj:       The kobject containing the group.
 377  * @group_name: The name of the group.
 378  * @link_name:  The name of the symlink to remove.
 379  */
 380 void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 381                                   const char *link_name)
 382 {
 383         struct kernfs_node *parent;
 384
 385         parent = kernfs_find_and_get(kobj->sd, group_name);
 386         if (parent) {
 387                 kernfs_remove_by_name(parent, link_name);
 388                 kernfs_put(parent);
 389         }
 390 }
 391 EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
 392
 393 /**
 394  * __compat_only_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing
 395  * to a group or an attribute
 396  * @kobj:               The kobject containing the group.
 397  * @target_kobj:        The target kobject.
 398  * @target_name:        The name of the target group or attribute.
 399  */
 400 int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
 401                                       struct kobject *target_kobj,
 402                                       const char *target_name)
 403 {
 404         struct kernfs_node *target;
 405         struct kernfs_node *entry;
 406         struct kernfs_node *link;
 407
 408         /*
 409          * We don't own @target_kobj and it may be removed at any time.
 410          * Synchronize using sysfs_symlink_target_lock. See sysfs_remove_dir()
 411          * for details.
 412          */
 413         spin_lock(&sysfs_symlink_target_lock);
 414         target = target_kobj->sd;
 415         if (target)
 416                 kernfs_get(target);
 417         spin_unlock(&sysfs_symlink_target_lock);
 418         if (!target)
 419                 return -ENOENT;
 420
 421         entry = kernfs_find_and_get(target_kobj->sd, target_name);
 422         if (!entry) {
 423                 kernfs_put(target);
 424                 return -ENOENT;
 425         }
 426
 427         link = kernfs_create_link(kobj->sd, target_name, entry);
 428         if (IS_ERR(link) && PTR_ERR(link) == -EEXIST)
 429                 sysfs_warn_dup(kobj->sd, target_name);
 430
 431         kernfs_put(entry);
 432         kernfs_put(target);
 433         return PTR_ERR_OR_ZERO(link);
 434 }
 435 EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);