fs/xattr.c

   1 /*
   2   File: fs/xattr.c
   3
   4   Extended attribute handling.
   5
   6   Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
   7   Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
   8   Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
   9  */
  10 #include <linux/fs.h>
  11 #include <linux/slab.h>
  12 #include <linux/file.h>
  13 #include <linux/xattr.h>
  14 #include <linux/mount.h>
  15 #include <linux/namei.h>
  16 #include <linux/security.h>
  17 #include <linux/evm.h>
  18 #include <linux/syscalls.h>
  19 #include <linux/module.h>
  20 #include <linux/fsnotify.h>
  21 #include <linux/audit.h>
  22 #include <asm/uaccess.h>
  23
  24
  25 /*
  26  * Check permissions for extended attribute access.  This is a bit complicated
  27  * because different namespaces have very different rules.
  28  */
  29 static int
  30 xattr_permission(struct inode *inode, const char *name, int mask)
  31 {
  32         /*
  33          * We can never set or remove an extended attribute on a read-only
  34          * filesystem  or on an immutable / append-only inode.
  35          */
  36         if (mask & MAY_WRITE) {
  37                 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
  38                         return -EPERM;
  39         }
  40
  41         /*
  42          * No restriction for security.* and system.* from the VFS.  Decision
  43          * on these is left to the underlying filesystem / security module.
  44          */
  45         if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
  46             !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
  47                 return 0;
  48
  49         /*
  50          * The trusted.* namespace can only be accessed by privileged users.
  51          */
  52         if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
  53                 if (!capable(CAP_SYS_ADMIN))
  54                         return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
  55                 return 0;
  56         }
  57
  58         /*
  59          * In the user.* namespace, only regular files and directories can have
  60          * extended attributes. For sticky directories, only the owner and
  61          * privileged users can write attributes.
  62          */
  63         if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
  64                 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
  65                         return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
  66                 if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
  67                     (mask & MAY_WRITE) && !inode_owner_or_capable(inode))
  68                         return -EPERM;
  69         }
  70
  71         return inode_permission(inode, mask);
  72 }
  73
  74 /**
  75  *  __vfs_setxattr_noperm - perform setxattr operation without performing
  76  *  permission checks.
  77  *
  78  *  @dentry - object to perform setxattr on
  79  *  @name - xattr name to set
  80  *  @value - value to set @name to
  81  *  @size - size of @value
  82  *  @flags - flags to pass into filesystem operations
  83  *
  84  *  returns the result of the internal setxattr or setsecurity operations.
  85  *
  86  *  This function requires the caller to lock the inode's i_mutex before it
  87  *  is executed. It also assumes that the caller will make the appropriate
  88  *  permission checks.
  89  */
  90 int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
  91                 const void *value, size_t size, int flags)
  92 {
  93         struct inode *inode = dentry->d_inode;
  94         int error = -EOPNOTSUPP;
  95         int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
  96                                    XATTR_SECURITY_PREFIX_LEN);
  97
  98         if (issec)
  99                 inode->i_flags &= ~S_NOSEC;
 100         if (inode->i_op->setxattr) {
 101                 error = inode->i_op->setxattr(dentry, name, value, size, flags);
 102                 if (!error) {
 103                         fsnotify_xattr(dentry);
 104                         security_inode_post_setxattr(dentry, name, value,
 105                                                      size, flags);
 106                 }
 107         } else if (issec) {
 108                 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
 109                 error = security_inode_setsecurity(inode, suffix, value,
 110                                                    size, flags);
 111                 if (!error)
 112                         fsnotify_xattr(dentry);
 113         }
 114
 115         return error;
 116 }
 117
 118
 119 int
 120 vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 121                 size_t size, int flags)
 122 {
 123         struct inode *inode = dentry->d_inode;
 124         int error;
 125
 126         error = xattr_permission(inode, name, MAY_WRITE);
 127         if (error)
 128                 return error;
 129
 130         mutex_lock(&inode->i_mutex);
 131         error = security_inode_setxattr(dentry, name, value, size, flags);
 132         if (error)
 133                 goto out;
 134
 135         error = __vfs_setxattr_noperm(dentry, name, value, size, flags);
 136
 137 out:
 138         mutex_unlock(&inode->i_mutex);
 139         return error;
 140 }
 141 EXPORT_SYMBOL_GPL(vfs_setxattr);
 142
 143 ssize_t
 144 xattr_getsecurity(struct inode *inode, const char *name, void *value,
 145                         size_t size)
 146 {
 147         void *buffer = NULL;
 148         ssize_t len;
 149
 150         if (!value || !size) {
 151                 len = security_inode_getsecurity(inode, name, &buffer, false);
 152                 goto out_noalloc;
 153         }
 154
 155         len = security_inode_getsecurity(inode, name, &buffer, true);
 156         if (len < 0)
 157                 return len;
 158         if (size < len) {
 159                 len = -ERANGE;
 160                 goto out;
 161         }
 162         memcpy(value, buffer, len);
 163 out:
 164         security_release_secctx(buffer, len);
 165 out_noalloc:
 166         return len;
 167 }
 168 EXPORT_SYMBOL_GPL(xattr_getsecurity);
 169
 170 /*
 171  * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
 172  *
 173  * Allocate memory, if not already allocated, or re-allocate correct size,
 174  * before retrieving the extended attribute.
 175  *
 176  * Returns the result of alloc, if failed, or the getxattr operation.
 177  */
 178 ssize_t
 179 vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value,
 180                    size_t xattr_size, gfp_t flags)
 181 {
 182         struct inode *inode = dentry->d_inode;
 183         char *value = *xattr_value;
 184         int error;
 185
 186         error = xattr_permission(inode, name, MAY_READ);
 187         if (error)
 188                 return error;
 189
 190         if (!inode->i_op->getxattr)
 191                 return -EOPNOTSUPP;
 192
 193         error = inode->i_op->getxattr(dentry, name, NULL, 0);
 194         if (error < 0)
 195                 return error;
 196
 197         if (!value || (error > xattr_size)) {
 198                 value = krealloc(*xattr_value, error + 1, flags);
 199                 if (!value)
 200                         return -ENOMEM;
 201                 memset(value, 0, error + 1);
 202         }
 203
 204         error = inode->i_op->getxattr(dentry, name, value, error);
 205         *xattr_value = value;
 206         return error;
 207 }
 208
 209 /* Compare an extended attribute value with the given value */
 210 int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name,
 211                   const char *value, size_t size, gfp_t flags)
 212 {
 213         char *xattr_value = NULL;
 214         int rc;
 215
 216         rc = vfs_getxattr_alloc(dentry, xattr_name, &xattr_value, 0, flags);
 217         if (rc < 0)
 218                 return rc;
 219
 220         if ((rc != size) || (memcmp(xattr_value, value, rc) != 0))
 221                 rc = -EINVAL;
 222         else
 223                 rc = 0;
 224         kfree(xattr_value);
 225         return rc;
 226 }
 227
 228 ssize_t
 229 vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
 230 {
 231         struct inode *inode = dentry->d_inode;
 232         int error;
 233
 234         error = xattr_permission(inode, name, MAY_READ);
 235         if (error)
 236                 return error;
 237
 238         error = security_inode_getxattr(dentry, name);
 239         if (error)
 240                 return error;
 241
 242         if (!strncmp(name, XATTR_SECURITY_PREFIX,
 243                                 XATTR_SECURITY_PREFIX_LEN)) {
 244                 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
 245                 int ret = xattr_getsecurity(inode, suffix, value, size);
 246                 /*
 247                  * Only overwrite the return value if a security module
 248                  * is actually active.
 249                  */
 250                 if (ret == -EOPNOTSUPP)
 251                         goto nolsm;
 252                 return ret;
 253         }
 254 nolsm:
 255         if (inode->i_op->getxattr)
 256                 error = inode->i_op->getxattr(dentry, name, value, size);
 257         else
 258                 error = -EOPNOTSUPP;
 259
 260         return error;
 261 }
 262 EXPORT_SYMBOL_GPL(vfs_getxattr);
 263
 264 ssize_t
 265 vfs_listxattr(struct dentry *d, char *list, size_t size)
 266 {
 267         ssize_t error;
 268
 269         error = security_inode_listxattr(d);
 270         if (error)
 271                 return error;
 272         error = -EOPNOTSUPP;
 273         if (d->d_inode->i_op->listxattr) {
 274                 error = d->d_inode->i_op->listxattr(d, list, size);
 275         } else {
 276                 error = security_inode_listsecurity(d->d_inode, list, size);
 277                 if (size && error > size)
 278                         error = -ERANGE;
 279         }
 280         return error;
 281 }
 282 EXPORT_SYMBOL_GPL(vfs_listxattr);
 283
 284 int
 285 vfs_removexattr(struct dentry *dentry, const char *name)
 286 {
 287         struct inode *inode = dentry->d_inode;
 288         int error;
 289
 290         if (!inode->i_op->removexattr)
 291                 return -EOPNOTSUPP;
 292
 293         error = xattr_permission(inode, name, MAY_WRITE);
 294         if (error)
 295                 return error;
 296
 297         error = security_inode_removexattr(dentry, name);
 298         if (error)
 299                 return error;
 300
 301         mutex_lock(&inode->i_mutex);
 302         error = inode->i_op->removexattr(dentry, name);
 303         mutex_unlock(&inode->i_mutex);
 304
 305         if (!error) {
 306                 fsnotify_xattr(dentry);
 307                 evm_inode_post_removexattr(dentry, name);
 308         }
 309         return error;
 310 }
 311 EXPORT_SYMBOL_GPL(vfs_removexattr);
 312
 313
 314 /*
 315  * Extended attribute SET operations
 316  */
 317 static long
 318 setxattr(struct dentry *d, const char __user *name, const void __user *value,
 319          size_t size, int flags)
 320 {
 321         int error;
 322         void *kvalue = NULL;
 323         char kname[XATTR_NAME_MAX + 1];
 324
 325         if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
 326                 return -EINVAL;
 327
 328         error = strncpy_from_user(kname, name, sizeof(kname));
 329         if (error == 0 || error == sizeof(kname))
 330                 error = -ERANGE;
 331         if (error < 0)
 332                 return error;
 333
 334         if (size) {
 335                 if (size > XATTR_SIZE_MAX)
 336                         return -E2BIG;
 337                 kvalue = memdup_user(value, size);
 338                 if (IS_ERR(kvalue))
 339                         return PTR_ERR(kvalue);
 340         }
 341
 342         error = vfs_setxattr(d, kname, kvalue, size, flags);
 343         kfree(kvalue);
 344         return error;
 345 }
 346
 347 SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
 348                 const char __user *, name, const void __user *, value,
 349                 size_t, size, int, flags)
 350 {
 351         struct path path;
 352         int error;
 353
 354         error = user_path(pathname, &path);
 355         if (error)
 356                 return error;
 357         error = mnt_want_write(path.mnt);
 358         if (!error) {
 359                 error = setxattr(path.dentry, name, value, size, flags);
 360                 mnt_drop_write(path.mnt);
 361         }
 362         path_put(&path);
 363         return error;
 364 }
 365
 366 SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
 367                 const char __user *, name, const void __user *, value,
 368                 size_t, size, int, flags)
 369 {
 370         struct path path;
 371         int error;
 372
 373         error = user_lpath(pathname, &path);
 374         if (error)
 375                 return error;
 376         error = mnt_want_write(path.mnt);
 377         if (!error) {
 378                 error = setxattr(path.dentry, name, value, size, flags);
 379                 mnt_drop_write(path.mnt);
 380         }
 381         path_put(&path);
 382         return error;
 383 }
 384
 385 SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
 386                 const void __user *,value, size_t, size, int, flags)
 387 {
 388         struct file *f;
 389         struct dentry *dentry;
 390         int error = -EBADF;
 391
 392         f = fget(fd);
 393         if (!f)
 394                 return error;
 395         dentry = f->f_path.dentry;
 396         audit_inode(NULL, dentry);
 397         error = mnt_want_write_file(f);
 398         if (!error) {
 399                 error = setxattr(dentry, name, value, size, flags);
 400                 mnt_drop_write(f->f_path.mnt);
 401         }
 402         fput(f);
 403         return error;
 404 }
 405
 406 /*
 407  * Extended attribute GET operations
 408  */
 409 static ssize_t
 410 getxattr(struct dentry *d, const char __user *name, void __user *value,
 411          size_t size)
 412 {
 413         ssize_t error;
 414         void *kvalue = NULL;
 415         char kname[XATTR_NAME_MAX + 1];
 416
 417         error = strncpy_from_user(kname, name, sizeof(kname));
 418         if (error == 0 || error == sizeof(kname))
 419                 error = -ERANGE;
 420         if (error < 0)
 421                 return error;
 422
 423         if (size) {
 424                 if (size > XATTR_SIZE_MAX)
 425                         size = XATTR_SIZE_MAX;
 426                 kvalue = kzalloc(size, GFP_KERNEL);
 427                 if (!kvalue)
 428                         return -ENOMEM;
 429         }
 430
 431         error = vfs_getxattr(d, kname, kvalue, size);
 432         if (error > 0) {
 433                 if (size && copy_to_user(value, kvalue, error))
 434                         error = -EFAULT;
 435         } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
 436                 /* The file system tried to returned a value bigger
 437                    than XATTR_SIZE_MAX bytes. Not possible. */
 438                 error = -E2BIG;
 439         }
 440         kfree(kvalue);
 441         return error;
 442 }
 443
 444 SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
 445                 const char __user *, name, void __user *, value, size_t, size)
 446 {
 447         struct path path;
 448         ssize_t error;
 449
 450         error = user_path(pathname, &path);
 451         if (error)
 452                 return error;
 453         error = getxattr(path.dentry, name, value, size);
 454         path_put(&path);
 455         return error;
 456 }
 457
 458 SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
 459                 const char __user *, name, void __user *, value, size_t, size)
 460 {
 461         struct path path;
 462         ssize_t error;
 463
 464         error = user_lpath(pathname, &path);
 465         if (error)
 466                 return error;
 467         error = getxattr(path.dentry, name, value, size);
 468         path_put(&path);
 469         return error;
 470 }
 471
 472 SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
 473                 void __user *, value, size_t, size)
 474 {
 475         struct file *f;
 476         ssize_t error = -EBADF;
 477
 478         f = fget(fd);
 479         if (!f)
 480                 return error;
 481         audit_inode(NULL, f->f_path.dentry);
 482         error = getxattr(f->f_path.dentry, name, value, size);
 483         fput(f);
 484         return error;
 485 }
 486
 487 /*
 488  * Extended attribute LIST operations
 489  */
 490 static ssize_t
 491 listxattr(struct dentry *d, char __user *list, size_t size)
 492 {
 493         ssize_t error;
 494         char *klist = NULL;
 495
 496         if (size) {
 497                 if (size > XATTR_LIST_MAX)
 498                         size = XATTR_LIST_MAX;
 499                 klist = kmalloc(size, GFP_KERNEL);
 500                 if (!klist)
 501                         return -ENOMEM;
 502         }
 503
 504         error = vfs_listxattr(d, klist, size);
 505         if (error > 0) {
 506                 if (size && copy_to_user(list, klist, error))
 507                         error = -EFAULT;
 508         } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
 509                 /* The file system tried to returned a list bigger
 510                    than XATTR_LIST_MAX bytes. Not possible. */
 511                 error = -E2BIG;
 512         }
 513         kfree(klist);
 514         return error;
 515 }
 516
 517 SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
 518                 size_t, size)
 519 {
 520         struct path path;
 521         ssize_t error;
 522
 523         error = user_path(pathname, &path);
 524         if (error)
 525                 return error;
 526         error = listxattr(path.dentry, list, size);
 527         path_put(&path);
 528         return error;
 529 }
 530
 531 SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
 532                 size_t, size)
 533 {
 534         struct path path;
 535         ssize_t error;
 536
 537         error = user_lpath(pathname, &path);
 538         if (error)
 539                 return error;
 540         error = listxattr(path.dentry, list, size);
 541         path_put(&path);
 542         return error;
 543 }
 544
 545 SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
 546 {
 547         struct file *f;
 548         ssize_t error = -EBADF;
 549
 550         f = fget(fd);
 551         if (!f)
 552                 return error;
 553         audit_inode(NULL, f->f_path.dentry);
 554         error = listxattr(f->f_path.dentry, list, size);
 555         fput(f);
 556         return error;
 557 }
 558
 559 /*
 560  * Extended attribute REMOVE operations
 561  */
 562 static long
 563 removexattr(struct dentry *d, const char __user *name)
 564 {
 565         int error;
 566         char kname[XATTR_NAME_MAX + 1];
 567
 568         error = strncpy_from_user(kname, name, sizeof(kname));
 569         if (error == 0 || error == sizeof(kname))
 570                 error = -ERANGE;
 571         if (error < 0)
 572                 return error;
 573
 574         return vfs_removexattr(d, kname);
 575 }
 576
 577 SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
 578                 const char __user *, name)
 579 {
 580         struct path path;
 581         int error;
 582
 583         error = user_path(pathname, &path);
 584         if (error)
 585                 return error;
 586         error = mnt_want_write(path.mnt);
 587         if (!error) {
 588                 error = removexattr(path.dentry, name);
 589                 mnt_drop_write(path.mnt);
 590         }
 591         path_put(&path);
 592         return error;
 593 }
 594
 595 SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
 596                 const char __user *, name)
 597 {
 598         struct path path;
 599         int error;
 600
 601         error = user_lpath(pathname, &path);
 602         if (error)
 603                 return error;
 604         error = mnt_want_write(path.mnt);
 605         if (!error) {
 606                 error = removexattr(path.dentry, name);
 607                 mnt_drop_write(path.mnt);
 608         }
 609         path_put(&path);
 610         return error;
 611 }
 612
 613 SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
 614 {
 615         struct file *f;
 616         struct dentry *dentry;
 617         int error = -EBADF;
 618
 619         f = fget(fd);
 620         if (!f)
 621                 return error;
 622         dentry = f->f_path.dentry;
 623         audit_inode(NULL, dentry);
 624         error = mnt_want_write_file(f);
 625         if (!error) {
 626                 error = removexattr(dentry, name);
 627                 mnt_drop_write(f->f_path.mnt);
 628         }
 629         fput(f);
 630         return error;
 631 }
 632
 633
 634 static const char *
 635 strcmp_prefix(const char *a, const char *a_prefix)
 636 {
 637         while (*a_prefix && *a == *a_prefix) {
 638                 a++;
 639                 a_prefix++;
 640         }
 641         return *a_prefix ? NULL : a;
 642 }
 643
 644 /*
 645  * In order to implement different sets of xattr operations for each xattr
 646  * prefix with the generic xattr API, a filesystem should create a
 647  * null-terminated array of struct xattr_handler (one for each prefix) and
 648  * hang a pointer to it off of the s_xattr field of the superblock.
 649  *
 650  * The generic_fooxattr() functions will use this list to dispatch xattr
 651  * operations to the correct xattr_handler.
 652  */
 653 #define for_each_xattr_handler(handlers, handler)               \
 654                 for ((handler) = *(handlers)++;                 \
 655                         (handler) != NULL;                      \
 656                         (handler) = *(handlers)++)
 657
 658 /*
 659  * Find the xattr_handler with the matching prefix.
 660  */
 661 static const struct xattr_handler *
 662 xattr_resolve_name(const struct xattr_handler **handlers, const char **name)
 663 {
 664         const struct xattr_handler *handler;
 665
 666         if (!*name)
 667                 return NULL;
 668
 669         for_each_xattr_handler(handlers, handler) {
 670                 const char *n = strcmp_prefix(*name, handler->prefix);
 671                 if (n) {
 672                         *name = n;
 673                         break;
 674                 }
 675         }
 676         return handler;
 677 }
 678
 679 /*
 680  * Find the handler for the prefix and dispatch its get() operation.
 681  */
 682 ssize_t
 683 generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
 684 {
 685         const struct xattr_handler *handler;
 686
 687         handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
 688         if (!handler)
 689                 return -EOPNOTSUPP;
 690         return handler->get(dentry, name, buffer, size, handler->flags);
 691 }
 692
 693 /*
 694  * Combine the results of the list() operation from every xattr_handler in the
 695  * list.
 696  */
 697 ssize_t
 698 generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 699 {
 700         const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
 701         unsigned int size = 0;
 702
 703         if (!buffer) {
 704                 for_each_xattr_handler(handlers, handler) {
 705                         size += handler->list(dentry, NULL, 0, NULL, 0,
 706                                               handler->flags);
 707                 }
 708         } else {
 709                 char *buf = buffer;
 710
 711                 for_each_xattr_handler(handlers, handler) {
 712                         size = handler->list(dentry, buf, buffer_size,
 713                                              NULL, 0, handler->flags);
 714                         if (size > buffer_size)
 715                                 return -ERANGE;
 716                         buf += size;
 717                         buffer_size -= size;
 718                 }
 719                 size = buf - buffer;
 720         }
 721         return size;
 722 }
 723
 724 /*
 725  * Find the handler for the prefix and dispatch its set() operation.
 726  */
 727 int
 728 generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
 729 {
 730         const struct xattr_handler *handler;
 731
 732         if (size == 0)
 733                 value = "";  /* empty EA, do not remove */
 734         handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
 735         if (!handler)
 736                 return -EOPNOTSUPP;
 737         return handler->set(dentry, name, value, size, flags, handler->flags);
 738 }
 739
 740 /*
 741  * Find the handler for the prefix and dispatch its set() operation to remove
 742  * any associated extended attribute.
 743  */
 744 int
 745 generic_removexattr(struct dentry *dentry, const char *name)
 746 {
 747         const struct xattr_handler *handler;
 748
 749         handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
 750         if (!handler)
 751                 return -EOPNOTSUPP;
 752         return handler->set(dentry, name, NULL, 0,
 753                             XATTR_REPLACE, handler->flags);
 754 }
 755
 756 EXPORT_SYMBOL(generic_getxattr);
 757 EXPORT_SYMBOL(generic_listxattr);
 758 EXPORT_SYMBOL(generic_setxattr);
 759 EXPORT_SYMBOL(generic_removexattr);