fs/ubifs/xattr.c

   1 /*
   2  * This file is part of UBIFS.
   3  *
   4  * Copyright (C) 2006-2008 Nokia Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc., 51
  17  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  *
  19  * Authors: Artem Bityutskiy (Битюцкий Артём)
  20  *          Adrian Hunter
  21  */
  22
  23 /*
  24  * This file implements UBIFS extended attributes support.
  25  *
  26  * Extended attributes are implemented as regular inodes with attached data,
  27  * which limits extended attribute size to UBIFS block size (4KiB). Names of
  28  * extended attributes are described by extended attribute entries (xentries),
  29  * which are almost identical to directory entries, but have different key type.
  30  *
  31  * In other words, the situation with extended attributes is very similar to
  32  * directories. Indeed, any inode (but of course not xattr inodes) may have a
  33  * number of associated xentries, just like directory inodes have associated
  34  * directory entries. Extended attribute entries store the name of the extended
  35  * attribute, the host inode number, and the extended attribute inode number.
  36  * Similarly, direntries store the name, the parent and the target inode
  37  * numbers. Thus, most of the common UBIFS mechanisms may be re-used for
  38  * extended attributes.
  39  *
  40  * The number of extended attributes is not limited, but there is Linux
  41  * limitation on the maximum possible size of the list of all extended
  42  * attributes associated with an inode (%XATTR_LIST_MAX), so UBIFS makes sure
  43  * the sum of all extended attribute names of the inode does not exceed that
  44  * limit.
  45  *
  46  * Extended attributes are synchronous, which means they are written to the
  47  * flash media synchronously and there is no write-back for extended attribute
  48  * inodes. The extended attribute values are not stored in compressed form on
  49  * the media.
  50  *
  51  * Since extended attributes are represented by regular inodes, they are cached
  52  * in the VFS inode cache. The xentries are cached in the LNC cache (see
  53  * tnc.c).
  54  *
  55  * ACL support is not implemented.
  56  */
  57
  58 #include "ubifs.h"
  59 #include <linux/fs.h>
  60 #include <linux/slab.h>
  61 #include <linux/xattr.h>
  62
  63 /*
  64  * Limit the number of extended attributes per inode so that the total size
  65  * (@xattr_size) is guaranteeded to fit in an 'unsigned int'.
  66  */
  67 #define MAX_XATTRS_PER_INODE 65535
  68
  69 /*
  70  * Extended attribute type constants.
  71  *
  72  * USER_XATTR: user extended attribute ("user.*")
  73  * TRUSTED_XATTR: trusted extended attribute ("trusted.*)
  74  * SECURITY_XATTR: security extended attribute ("security.*")
  75  */
  76 enum {
  77         USER_XATTR,
  78         TRUSTED_XATTR,
  79         SECURITY_XATTR,
  80 };
  81
  82 static const struct inode_operations empty_iops;
  83 static const struct file_operations empty_fops;
  84
  85 /**
  86  * create_xattr - create an extended attribute.
  87  * @c: UBIFS file-system description object
  88  * @host: host inode
  89  * @nm: extended attribute name
  90  * @value: extended attribute value
  91  * @size: size of extended attribute value
  92  *
  93  * This is a helper function which creates an extended attribute of name @nm
  94  * and value @value for inode @host. The host inode is also updated on flash
  95  * because the ctime and extended attribute accounting data changes. This
  96  * function returns zero in case of success and a negative error code in case
  97  * of failure.
  98  */
  99 static int create_xattr(struct ubifs_info *c, struct inode *host,
 100                         const struct fscrypt_name *nm, const void *value, int size)
 101 {
 102         int err, names_len;
 103         struct inode *inode;
 104         struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
 105         struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
 106                                 .new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
 107                                 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
 108
 109         if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE) {
 110                 ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
 111                           host->i_ino, host_ui->xattr_cnt);
 112                 return -ENOSPC;
 113         }
 114         /*
 115          * Linux limits the maximum size of the extended attribute names list
 116          * to %XATTR_LIST_MAX. This means we should not allow creating more
 117          * extended attributes if the name list becomes larger. This limitation
 118          * is artificial for UBIFS, though.
 119          */
 120         names_len = host_ui->xattr_names + host_ui->xattr_cnt + fname_len(nm) + 1;
 121         if (names_len > XATTR_LIST_MAX) {
 122                 ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
 123                           host->i_ino, names_len, XATTR_LIST_MAX);
 124                 return -ENOSPC;
 125         }
 126
 127         err = ubifs_budget_space(c, &req);
 128         if (err)
 129                 return err;
 130
 131         inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
 132         if (IS_ERR(inode)) {
 133                 err = PTR_ERR(inode);
 134                 goto out_budg;
 135         }
 136
 137         /* Re-define all operations to be "nothing" */
 138         inode->i_mapping->a_ops = &empty_aops;
 139         inode->i_op = &empty_iops;
 140         inode->i_fop = &empty_fops;
 141
 142         inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME;
 143         ui = ubifs_inode(inode);
 144         ui->xattr = 1;
 145         ui->flags |= UBIFS_XATTR_FL;
 146         ui->data = kmemdup(value, size, GFP_NOFS);
 147         if (!ui->data) {
 148                 err = -ENOMEM;
 149                 goto out_free;
 150         }
 151         inode->i_size = ui->ui_size = size;
 152         ui->data_len = size;
 153
 154         mutex_lock(&host_ui->ui_mutex);
 155         host->i_ctime = current_time(host);
 156         host_ui->xattr_cnt += 1;
 157         host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
 158         host_ui->xattr_size += CALC_XATTR_BYTES(size);
 159         host_ui->xattr_names += fname_len(nm);
 160
 161         /*
 162          * We handle UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT here because we
 163          * have to set the UBIFS_CRYPT_FL flag on the host inode.
 164          * To avoid multiple updates of the same inode in the same operation,
 165          * let's do it here.
 166          */
 167         if (strcmp(fname_name(nm), UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
 168                 host_ui->flags |= UBIFS_CRYPT_FL;
 169
 170         err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
 171         if (err)
 172                 goto out_cancel;
 173         ubifs_set_inode_flags(host);
 174         mutex_unlock(&host_ui->ui_mutex);
 175
 176         ubifs_release_budget(c, &req);
 177         insert_inode_hash(inode);
 178         iput(inode);
 179         return 0;
 180
 181 out_cancel:
 182         host_ui->xattr_cnt -= 1;
 183         host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
 184         host_ui->xattr_size -= CALC_XATTR_BYTES(size);
 185         host_ui->xattr_names -= fname_len(nm);
 186         host_ui->flags &= ~UBIFS_CRYPT_FL;
 187         mutex_unlock(&host_ui->ui_mutex);
 188 out_free:
 189         make_bad_inode(inode);
 190         iput(inode);
 191 out_budg:
 192         ubifs_release_budget(c, &req);
 193         return err;
 194 }
 195
 196 /**
 197  * change_xattr - change an extended attribute.
 198  * @c: UBIFS file-system description object
 199  * @host: host inode
 200  * @inode: extended attribute inode
 201  * @value: extended attribute value
 202  * @size: size of extended attribute value
 203  *
 204  * This helper function changes the value of extended attribute @inode with new
 205  * data from @value. Returns zero in case of success and a negative error code
 206  * in case of failure.
 207  */
 208 static int change_xattr(struct ubifs_info *c, struct inode *host,
 209                         struct inode *inode, const void *value, int size)
 210 {
 211         int err;
 212         struct ubifs_inode *host_ui = ubifs_inode(host);
 213         struct ubifs_inode *ui = ubifs_inode(inode);
 214         void *buf = NULL;
 215         int old_size;
 216         struct ubifs_budget_req req = { .dirtied_ino = 2,
 217                 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
 218
 219         ubifs_assert(c, ui->data_len == inode->i_size);
 220         err = ubifs_budget_space(c, &req);
 221         if (err)
 222                 return err;
 223
 224         buf = kmemdup(value, size, GFP_NOFS);
 225         if (!buf) {
 226                 err = -ENOMEM;
 227                 goto out_free;
 228         }
 229         mutex_lock(&ui->ui_mutex);
 230         kfree(ui->data);
 231         ui->data = buf;
 232         inode->i_size = ui->ui_size = size;
 233         old_size = ui->data_len;
 234         ui->data_len = size;
 235         mutex_unlock(&ui->ui_mutex);
 236
 237         mutex_lock(&host_ui->ui_mutex);
 238         host->i_ctime = current_time(host);
 239         host_ui->xattr_size -= CALC_XATTR_BYTES(old_size);
 240         host_ui->xattr_size += CALC_XATTR_BYTES(size);
 241
 242         /*
 243          * It is important to write the host inode after the xattr inode
 244          * because if the host inode gets synchronized (via 'fsync()'), then
 245          * the extended attribute inode gets synchronized, because it goes
 246          * before the host inode in the write-buffer.
 247          */
 248         err = ubifs_jnl_change_xattr(c, inode, host);
 249         if (err)
 250                 goto out_cancel;
 251         mutex_unlock(&host_ui->ui_mutex);
 252
 253         ubifs_release_budget(c, &req);
 254         return 0;
 255
 256 out_cancel:
 257         host_ui->xattr_size -= CALC_XATTR_BYTES(size);
 258         host_ui->xattr_size += CALC_XATTR_BYTES(old_size);
 259         mutex_unlock(&host_ui->ui_mutex);
 260         make_bad_inode(inode);
 261 out_free:
 262         ubifs_release_budget(c, &req);
 263         return err;
 264 }
 265
 266 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
 267 {
 268         struct inode *inode;
 269
 270         inode = ubifs_iget(c->vfs_sb, inum);
 271         if (IS_ERR(inode)) {
 272                 ubifs_err(c, "dead extended attribute entry, error %d",
 273                           (int)PTR_ERR(inode));
 274                 return inode;
 275         }
 276         if (ubifs_inode(inode)->xattr)
 277                 return inode;
 278         ubifs_err(c, "corrupt extended attribute entry");
 279         iput(inode);
 280         return ERR_PTR(-EINVAL);
 281 }
 282
 283 int ubifs_xattr_set(struct inode *host, const char *name, const void *value,
 284                     size_t size, int flags, bool check_lock)
 285 {
 286         struct inode *inode;
 287         struct ubifs_info *c = host->i_sb->s_fs_info;
 288         struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
 289         struct ubifs_dent_node *xent;
 290         union ubifs_key key;
 291         int err;
 292
 293         if (check_lock)
 294                 ubifs_assert(c, inode_is_locked(host));
 295
 296         if (size > UBIFS_MAX_INO_DATA)
 297                 return -ERANGE;
 298
 299         if (fname_len(&nm) > UBIFS_MAX_NLEN)
 300                 return -ENAMETOOLONG;
 301
 302         xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
 303         if (!xent)
 304                 return -ENOMEM;
 305
 306         /*
 307          * The extended attribute entries are stored in LNC, so multiple
 308          * look-ups do not involve reading the flash.
 309          */
 310         xent_key_init(c, &key, host->i_ino, &nm);
 311         err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
 312         if (err) {
 313                 if (err != -ENOENT)
 314                         goto out_free;
 315
 316                 if (flags & XATTR_REPLACE)
 317                         /* We are asked not to create the xattr */
 318                         err = -ENODATA;
 319                 else
 320                         err = create_xattr(c, host, &nm, value, size);
 321                 goto out_free;
 322         }
 323
 324         if (flags & XATTR_CREATE) {
 325                 /* We are asked not to replace the xattr */
 326                 err = -EEXIST;
 327                 goto out_free;
 328         }
 329
 330         inode = iget_xattr(c, le64_to_cpu(xent->inum));
 331         if (IS_ERR(inode)) {
 332                 err = PTR_ERR(inode);
 333                 goto out_free;
 334         }
 335
 336         err = change_xattr(c, host, inode, value, size);
 337         iput(inode);
 338
 339 out_free:
 340         kfree(xent);
 341         return err;
 342 }
 343
 344 ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf,
 345                         size_t size)
 346 {
 347         struct inode *inode;
 348         struct ubifs_info *c = host->i_sb->s_fs_info;
 349         struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
 350         struct ubifs_inode *ui;
 351         struct ubifs_dent_node *xent;
 352         union ubifs_key key;
 353         int err;
 354
 355         if (fname_len(&nm) > UBIFS_MAX_NLEN)
 356                 return -ENAMETOOLONG;
 357
 358         xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
 359         if (!xent)
 360                 return -ENOMEM;
 361
 362         xent_key_init(c, &key, host->i_ino, &nm);
 363         err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
 364         if (err) {
 365                 if (err == -ENOENT)
 366                         err = -ENODATA;
 367                 goto out_unlock;
 368         }
 369
 370         inode = iget_xattr(c, le64_to_cpu(xent->inum));
 371         if (IS_ERR(inode)) {
 372                 err = PTR_ERR(inode);
 373                 goto out_unlock;
 374         }
 375
 376         ui = ubifs_inode(inode);
 377         ubifs_assert(c, inode->i_size == ui->data_len);
 378         ubifs_assert(c, ubifs_inode(host)->xattr_size > ui->data_len);
 379
 380         mutex_lock(&ui->ui_mutex);
 381         if (buf) {
 382                 /* If @buf is %NULL we are supposed to return the length */
 383                 if (ui->data_len > size) {
 384                         err = -ERANGE;
 385                         goto out_iput;
 386                 }
 387
 388                 memcpy(buf, ui->data, ui->data_len);
 389         }
 390         err = ui->data_len;
 391
 392 out_iput:
 393         mutex_unlock(&ui->ui_mutex);
 394         iput(inode);
 395 out_unlock:
 396         kfree(xent);
 397         return err;
 398 }
 399
 400 static bool xattr_visible(const char *name)
 401 {
 402         /* File encryption related xattrs are for internal use only */
 403         if (strcmp(name, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
 404                 return false;
 405
 406         /* Show trusted namespace only for "power" users */
 407         if (strncmp(name, XATTR_TRUSTED_PREFIX,
 408                     XATTR_TRUSTED_PREFIX_LEN) == 0 && !capable(CAP_SYS_ADMIN))
 409                 return false;
 410
 411         return true;
 412 }
 413
 414 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 415 {
 416         union ubifs_key key;
 417         struct inode *host = d_inode(dentry);
 418         struct ubifs_info *c = host->i_sb->s_fs_info;
 419         struct ubifs_inode *host_ui = ubifs_inode(host);
 420         struct ubifs_dent_node *xent, *pxent = NULL;
 421         int err, len, written = 0;
 422         struct fscrypt_name nm = {0};
 423
 424         dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
 425                 dentry, size);
 426
 427         len = host_ui->xattr_names + host_ui->xattr_cnt;
 428         if (!buffer)
 429                 /*
 430                  * We should return the minimum buffer size which will fit a
 431                  * null-terminated list of all the extended attribute names.
 432                  */
 433                 return len;
 434
 435         if (len > size)
 436                 return -ERANGE;
 437
 438         lowest_xent_key(c, &key, host->i_ino);
 439         while (1) {
 440                 xent = ubifs_tnc_next_ent(c, &key, &nm);
 441                 if (IS_ERR(xent)) {
 442                         err = PTR_ERR(xent);
 443                         break;
 444                 }
 445
 446                 fname_name(&nm) = xent->name;
 447                 fname_len(&nm) = le16_to_cpu(xent->nlen);
 448
 449                 if (xattr_visible(xent->name)) {
 450                         memcpy(buffer + written, fname_name(&nm), fname_len(&nm) + 1);
 451                         written += fname_len(&nm) + 1;
 452                 }
 453
 454                 kfree(pxent);
 455                 pxent = xent;
 456                 key_read(c, &xent->key, &key);
 457         }
 458
 459         kfree(pxent);
 460         if (err != -ENOENT) {
 461                 ubifs_err(c, "cannot find next direntry, error %d", err);
 462                 return err;
 463         }
 464
 465         ubifs_assert(c, written <= size);
 466         return written;
 467 }
 468
 469 static int remove_xattr(struct ubifs_info *c, struct inode *host,
 470                         struct inode *inode, const struct fscrypt_name *nm)
 471 {
 472         int err;
 473         struct ubifs_inode *host_ui = ubifs_inode(host);
 474         struct ubifs_inode *ui = ubifs_inode(inode);
 475         struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
 476                                 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
 477
 478         ubifs_assert(c, ui->data_len == inode->i_size);
 479
 480         err = ubifs_budget_space(c, &req);
 481         if (err)
 482                 return err;
 483
 484         mutex_lock(&host_ui->ui_mutex);
 485         host->i_ctime = current_time(host);
 486         host_ui->xattr_cnt -= 1;
 487         host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
 488         host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
 489         host_ui->xattr_names -= fname_len(nm);
 490
 491         err = ubifs_jnl_delete_xattr(c, host, inode, nm);
 492         if (err)
 493                 goto out_cancel;
 494         mutex_unlock(&host_ui->ui_mutex);
 495
 496         ubifs_release_budget(c, &req);
 497         return 0;
 498
 499 out_cancel:
 500         host_ui->xattr_cnt += 1;
 501         host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
 502         host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
 503         host_ui->xattr_names += fname_len(nm);
 504         mutex_unlock(&host_ui->ui_mutex);
 505         ubifs_release_budget(c, &req);
 506         make_bad_inode(inode);
 507         return err;
 508 }
 509
 510 /**
 511  * ubifs_evict_xattr_inode - Evict an xattr inode.
 512  * @c: UBIFS file-system description object
 513  * @xattr_inum: xattr inode number
 514  *
 515  * When an inode that hosts xattrs is being removed we have to make sure
 516  * that cached inodes of the xattrs also get removed from the inode cache
 517  * otherwise we'd waste memory. This function looks up an inode from the
 518  * inode cache and clears the link counter such that iput() will evict
 519  * the inode.
 520  */
 521 void ubifs_evict_xattr_inode(struct ubifs_info *c, ino_t xattr_inum)
 522 {
 523         struct inode *inode;
 524
 525         inode = ilookup(c->vfs_sb, xattr_inum);
 526         if (inode) {
 527                 clear_nlink(inode);
 528                 iput(inode);
 529         }
 530 }
 531
 532 static int ubifs_xattr_remove(struct inode *host, const char *name)
 533 {
 534         struct inode *inode;
 535         struct ubifs_info *c = host->i_sb->s_fs_info;
 536         struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
 537         struct ubifs_dent_node *xent;
 538         union ubifs_key key;
 539         int err;
 540
 541         ubifs_assert(c, inode_is_locked(host));
 542
 543         if (fname_len(&nm) > UBIFS_MAX_NLEN)
 544                 return -ENAMETOOLONG;
 545
 546         xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
 547         if (!xent)
 548                 return -ENOMEM;
 549
 550         xent_key_init(c, &key, host->i_ino, &nm);
 551         err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
 552         if (err) {
 553                 if (err == -ENOENT)
 554                         err = -ENODATA;
 555                 goto out_free;
 556         }
 557
 558         inode = iget_xattr(c, le64_to_cpu(xent->inum));
 559         if (IS_ERR(inode)) {
 560                 err = PTR_ERR(inode);
 561                 goto out_free;
 562         }
 563
 564         ubifs_assert(c, inode->i_nlink == 1);
 565         clear_nlink(inode);
 566         err = remove_xattr(c, host, inode, &nm);
 567         if (err)
 568                 set_nlink(inode, 1);
 569
 570         /* If @i_nlink is 0, 'iput()' will delete the inode */
 571         iput(inode);
 572
 573 out_free:
 574         kfree(xent);
 575         return err;
 576 }
 577
 578 #ifdef CONFIG_UBIFS_FS_SECURITY
 579 static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
 580                       void *fs_info)
 581 {
 582         const struct xattr *xattr;
 583         char *name;
 584         int err = 0;
 585
 586         for (xattr = xattr_array; xattr->name != NULL; xattr++) {
 587                 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
 588                                strlen(xattr->name) + 1, GFP_NOFS);
 589                 if (!name) {
 590                         err = -ENOMEM;
 591                         break;
 592                 }
 593                 strcpy(name, XATTR_SECURITY_PREFIX);
 594                 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
 595                 /*
 596                  * creating a new inode without holding the inode rwsem,
 597                  * no need to check whether inode is locked.
 598                  */
 599                 err = ubifs_xattr_set(inode, name, xattr->value,
 600                                       xattr->value_len, 0, false);
 601                 kfree(name);
 602                 if (err < 0)
 603                         break;
 604         }
 605
 606         return err;
 607 }
 608
 609 int ubifs_init_security(struct inode *dentry, struct inode *inode,
 610                         const struct qstr *qstr)
 611 {
 612         int err;
 613
 614         err = security_inode_init_security(inode, dentry, qstr,
 615                                            &init_xattrs, 0);
 616         if (err) {
 617                 struct ubifs_info *c = dentry->i_sb->s_fs_info;
 618                 ubifs_err(c, "cannot initialize security for inode %lu, error %d",
 619                           inode->i_ino, err);
 620         }
 621         return err;
 622 }
 623 #endif
 624
 625 static int xattr_get(const struct xattr_handler *handler,
 626                            struct dentry *dentry, struct inode *inode,
 627                            const char *name, void *buffer, size_t size)
 628 {
 629         dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
 630                 inode->i_ino, dentry, size);
 631
 632         name = xattr_full_name(handler, name);
 633         return ubifs_xattr_get(inode, name, buffer, size);
 634 }
 635
 636 static int xattr_set(const struct xattr_handler *handler,
 637                            struct dentry *dentry, struct inode *inode,
 638                            const char *name, const void *value,
 639                            size_t size, int flags)
 640 {
 641         dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
 642                 name, inode->i_ino, dentry, size);
 643
 644         name = xattr_full_name(handler, name);
 645
 646         if (value)
 647                 return ubifs_xattr_set(inode, name, value, size, flags, true);
 648         else
 649                 return ubifs_xattr_remove(inode, name);
 650 }
 651
 652 static const struct xattr_handler ubifs_user_xattr_handler = {
 653         .prefix = XATTR_USER_PREFIX,
 654         .get = xattr_get,
 655         .set = xattr_set,
 656 };
 657
 658 static const struct xattr_handler ubifs_trusted_xattr_handler = {
 659         .prefix = XATTR_TRUSTED_PREFIX,
 660         .get = xattr_get,
 661         .set = xattr_set,
 662 };
 663
 664 #ifdef CONFIG_UBIFS_FS_SECURITY
 665 static const struct xattr_handler ubifs_security_xattr_handler = {
 666         .prefix = XATTR_SECURITY_PREFIX,
 667         .get = xattr_get,
 668         .set = xattr_set,
 669 };
 670 #endif
 671
 672 const struct xattr_handler *ubifs_xattr_handlers[] = {
 673         &ubifs_user_xattr_handler,
 674         &ubifs_trusted_xattr_handler,
 675 #ifdef CONFIG_UBIFS_FS_SECURITY
 676         &ubifs_security_xattr_handler,
 677 #endif
 678         NULL
 679 };