linux/fs/xattr.c
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   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/export.h>
  20#include <linux/fsnotify.h>
  21#include <linux/audit.h>
  22#include <linux/vmalloc.h>
  23
  24#include <asm/uaccess.h>
  25
  26/*
  27 * Check permissions for extended attribute access.  This is a bit complicated
  28 * because different namespaces have very different rules.
  29 */
  30static int
  31xattr_permission(struct inode *inode, const char *name, int mask)
  32{
  33        /*
  34         * We can never set or remove an extended attribute on a read-only
  35         * filesystem  or on an immutable / append-only inode.
  36         */
  37        if (mask & MAY_WRITE) {
  38                if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
  39                        return -EPERM;
  40        }
  41
  42        /*
  43         * No restriction for security.* and system.* from the VFS.  Decision
  44         * on these is left to the underlying filesystem / security module.
  45         */
  46        if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
  47            !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
  48                return 0;
  49
  50        /*
  51         * The trusted.* namespace can only be accessed by privileged users.
  52         */
  53        if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
  54                if (!capable(CAP_SYS_ADMIN))
  55                        return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
  56                return 0;
  57        }
  58
  59        /*
  60         * In the user.* namespace, only regular files and directories can have
  61         * extended attributes. For sticky directories, only the owner and
  62         * privileged users can write attributes.
  63         */
  64        if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
  65                if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
  66                        return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
  67                if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
  68                    (mask & MAY_WRITE) && !inode_owner_or_capable(inode))
  69                        return -EPERM;
  70        }
  71
  72        return inode_permission(inode, mask);
  73}
  74
  75/**
  76 *  __vfs_setxattr_noperm - perform setxattr operation without performing
  77 *  permission checks.
  78 *
  79 *  @dentry - object to perform setxattr on
  80 *  @name - xattr name to set
  81 *  @value - value to set @name to
  82 *  @size - size of @value
  83 *  @flags - flags to pass into filesystem operations
  84 *
  85 *  returns the result of the internal setxattr or setsecurity operations.
  86 *
  87 *  This function requires the caller to lock the inode's i_mutex before it
  88 *  is executed. It also assumes that the caller will make the appropriate
  89 *  permission checks.
  90 */
  91int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
  92                const void *value, size_t size, int flags)
  93{
  94        struct inode *inode = dentry->d_inode;
  95        int error = -EOPNOTSUPP;
  96        int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
  97                                   XATTR_SECURITY_PREFIX_LEN);
  98
  99        if (issec)
 100                inode->i_flags &= ~S_NOSEC;
 101        if (inode->i_op->setxattr) {
 102                error = inode->i_op->setxattr(dentry, name, value, size, flags);
 103                if (!error) {
 104                        fsnotify_xattr(dentry);
 105                        security_inode_post_setxattr(dentry, name, value,
 106                                                     size, flags);
 107                }
 108        } else if (issec) {
 109                const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
 110                error = security_inode_setsecurity(inode, suffix, value,
 111                                                   size, flags);
 112                if (!error)
 113                        fsnotify_xattr(dentry);
 114        }
 115
 116        return error;
 117}
 118
 119
 120int
 121vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 122                size_t size, int flags)
 123{
 124        struct inode *inode = dentry->d_inode;
 125        int error;
 126
 127        error = xattr_permission(inode, name, MAY_WRITE);
 128        if (error)
 129                return error;
 130
 131        mutex_lock(&inode->i_mutex);
 132        error = security_inode_setxattr(dentry, name, value, size, flags);
 133        if (error)
 134                goto out;
 135
 136        error = __vfs_setxattr_noperm(dentry, name, value, size, flags);
 137
 138out:
 139        mutex_unlock(&inode->i_mutex);
 140        return error;
 141}
 142EXPORT_SYMBOL_GPL(vfs_setxattr);
 143
 144ssize_t
 145xattr_getsecurity(struct inode *inode, const char *name, void *value,
 146                        size_t size)
 147{
 148        void *buffer = NULL;
 149        ssize_t len;
 150
 151        if (!value || !size) {
 152                len = security_inode_getsecurity(inode, name, &buffer, false);
 153                goto out_noalloc;
 154        }
 155
 156        len = security_inode_getsecurity(inode, name, &buffer, true);
 157        if (len < 0)
 158                return len;
 159        if (size < len) {
 160                len = -ERANGE;
 161                goto out;
 162        }
 163        memcpy(value, buffer, len);
 164out:
 165        security_release_secctx(buffer, len);
 166out_noalloc:
 167        return len;
 168}
 169EXPORT_SYMBOL_GPL(xattr_getsecurity);
 170
 171/*
 172 * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
 173 *
 174 * Allocate memory, if not already allocated, or re-allocate correct size,
 175 * before retrieving the extended attribute.
 176 *
 177 * Returns the result of alloc, if failed, or the getxattr operation.
 178 */
 179ssize_t
 180vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value,
 181                   size_t xattr_size, gfp_t flags)
 182{
 183        struct inode *inode = dentry->d_inode;
 184        char *value = *xattr_value;
 185        int error;
 186
 187        error = xattr_permission(inode, name, MAY_READ);
 188        if (error)
 189                return error;
 190
 191        if (!inode->i_op->getxattr)
 192                return -EOPNOTSUPP;
 193
 194        error = inode->i_op->getxattr(dentry, name, NULL, 0);
 195        if (error < 0)
 196                return error;
 197
 198        if (!value || (error > xattr_size)) {
 199                value = krealloc(*xattr_value, error + 1, flags);
 200                if (!value)
 201                        return -ENOMEM;
 202                memset(value, 0, error + 1);
 203        }
 204
 205        error = inode->i_op->getxattr(dentry, name, value, error);
 206        *xattr_value = value;
 207        return error;
 208}
 209
 210/* Compare an extended attribute value with the given value */
 211int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name,
 212                  const char *value, size_t size, gfp_t flags)
 213{
 214        char *xattr_value = NULL;
 215        int rc;
 216
 217        rc = vfs_getxattr_alloc(dentry, xattr_name, &xattr_value, 0, flags);
 218        if (rc < 0)
 219                return rc;
 220
 221        if ((rc != size) || (memcmp(xattr_value, value, rc) != 0))
 222                rc = -EINVAL;
 223        else
 224                rc = 0;
 225        kfree(xattr_value);
 226        return rc;
 227}
 228
 229ssize_t
 230vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
 231{
 232        struct inode *inode = dentry->d_inode;
 233        int error;
 234
 235        error = xattr_permission(inode, name, MAY_READ);
 236        if (error)
 237                return error;
 238
 239        error = security_inode_getxattr(dentry, name);
 240        if (error)
 241                return error;
 242
 243        if (!strncmp(name, XATTR_SECURITY_PREFIX,
 244                                XATTR_SECURITY_PREFIX_LEN)) {
 245                const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
 246                int ret = xattr_getsecurity(inode, suffix, value, size);
 247                /*
 248                 * Only overwrite the return value if a security module
 249                 * is actually active.
 250                 */
 251                if (ret == -EOPNOTSUPP)
 252                        goto nolsm;
 253                return ret;
 254        }
 255nolsm:
 256        if (inode->i_op->getxattr)
 257                error = inode->i_op->getxattr(dentry, name, value, size);
 258        else
 259                error = -EOPNOTSUPP;
 260
 261        return error;
 262}
 263EXPORT_SYMBOL_GPL(vfs_getxattr);
 264
 265ssize_t
 266vfs_listxattr(struct dentry *d, char *list, size_t size)
 267{
 268        ssize_t error;
 269
 270        error = security_inode_listxattr(d);
 271        if (error)
 272                return error;
 273        error = -EOPNOTSUPP;
 274        if (d->d_inode->i_op->listxattr) {
 275                error = d->d_inode->i_op->listxattr(d, list, size);
 276        } else {
 277                error = security_inode_listsecurity(d->d_inode, list, size);
 278                if (size && error > size)
 279                        error = -ERANGE;
 280        }
 281        return error;
 282}
 283EXPORT_SYMBOL_GPL(vfs_listxattr);
 284
 285int
 286vfs_removexattr(struct dentry *dentry, const char *name)
 287{
 288        struct inode *inode = dentry->d_inode;
 289        int error;
 290
 291        if (!inode->i_op->removexattr)
 292                return -EOPNOTSUPP;
 293
 294        error = xattr_permission(inode, name, MAY_WRITE);
 295        if (error)
 296                return error;
 297
 298        error = security_inode_removexattr(dentry, name);
 299        if (error)
 300                return error;
 301
 302        mutex_lock(&inode->i_mutex);
 303        error = inode->i_op->removexattr(dentry, name);
 304        mutex_unlock(&inode->i_mutex);
 305
 306        if (!error) {
 307                fsnotify_xattr(dentry);
 308                evm_inode_post_removexattr(dentry, name);
 309        }
 310        return error;
 311}
 312EXPORT_SYMBOL_GPL(vfs_removexattr);
 313
 314
 315/*
 316 * Extended attribute SET operations
 317 */
 318static long
 319setxattr(struct dentry *d, const char __user *name, const void __user *value,
 320         size_t size, int flags)
 321{
 322        int error;
 323        void *kvalue = NULL;
 324        void *vvalue = NULL;    /* If non-NULL, we used vmalloc() */
 325        char kname[XATTR_NAME_MAX + 1];
 326
 327        if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
 328                return -EINVAL;
 329
 330        error = strncpy_from_user(kname, name, sizeof(kname));
 331        if (error == 0 || error == sizeof(kname))
 332                error = -ERANGE;
 333        if (error < 0)
 334                return error;
 335
 336        if (size) {
 337                if (size > XATTR_SIZE_MAX)
 338                        return -E2BIG;
 339                kvalue = kmalloc(size, GFP_KERNEL | __GFP_NOWARN);
 340                if (!kvalue) {
 341                        vvalue = vmalloc(size);
 342                        if (!vvalue)
 343                                return -ENOMEM;
 344                        kvalue = vvalue;
 345                }
 346                if (copy_from_user(kvalue, value, size)) {
 347                        error = -EFAULT;
 348                        goto out;
 349                }
 350        }
 351
 352        error = vfs_setxattr(d, kname, kvalue, size, flags);
 353out:
 354        if (vvalue)
 355                vfree(vvalue);
 356        else
 357                kfree(kvalue);
 358        return error;
 359}
 360
 361SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
 362                const char __user *, name, const void __user *, value,
 363                size_t, size, int, flags)
 364{
 365        struct path path;
 366        int error;
 367
 368        error = user_path(pathname, &path);
 369        if (error)
 370                return error;
 371        error = mnt_want_write(path.mnt);
 372        if (!error) {
 373                error = setxattr(path.dentry, name, value, size, flags);
 374                mnt_drop_write(path.mnt);
 375        }
 376        path_put(&path);
 377        return error;
 378}
 379
 380SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
 381                const char __user *, name, const void __user *, value,
 382                size_t, size, int, flags)
 383{
 384        struct path path;
 385        int error;
 386
 387        error = user_lpath(pathname, &path);
 388        if (error)
 389                return error;
 390        error = mnt_want_write(path.mnt);
 391        if (!error) {
 392                error = setxattr(path.dentry, name, value, size, flags);
 393                mnt_drop_write(path.mnt);
 394        }
 395        path_put(&path);
 396        return error;
 397}
 398
 399SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
 400                const void __user *,value, size_t, size, int, flags)
 401{
 402        int fput_needed;
 403        struct file *f;
 404        struct dentry *dentry;
 405        int error = -EBADF;
 406
 407        f = fget_light(fd, &fput_needed);
 408        if (!f)
 409                return error;
 410        dentry = f->f_path.dentry;
 411        audit_inode(NULL, dentry);
 412        error = mnt_want_write_file(f);
 413        if (!error) {
 414                error = setxattr(dentry, name, value, size, flags);
 415                mnt_drop_write_file(f);
 416        }
 417        fput_light(f, fput_needed);
 418        return error;
 419}
 420
 421/*
 422 * Extended attribute GET operations
 423 */
 424static ssize_t
 425getxattr(struct dentry *d, const char __user *name, void __user *value,
 426         size_t size)
 427{
 428        ssize_t error;
 429        void *kvalue = NULL;
 430        char kname[XATTR_NAME_MAX + 1];
 431
 432        error = strncpy_from_user(kname, name, sizeof(kname));
 433        if (error == 0 || error == sizeof(kname))
 434                error = -ERANGE;
 435        if (error < 0)
 436                return error;
 437
 438        if (size) {
 439                if (size > XATTR_SIZE_MAX)
 440                        size = XATTR_SIZE_MAX;
 441                kvalue = kzalloc(size, GFP_KERNEL);
 442                if (!kvalue)
 443                        return -ENOMEM;
 444        }
 445
 446        error = vfs_getxattr(d, kname, kvalue, size);
 447        if (error > 0) {
 448                if (size && copy_to_user(value, kvalue, error))
 449                        error = -EFAULT;
 450        } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
 451                /* The file system tried to returned a value bigger
 452                   than XATTR_SIZE_MAX bytes. Not possible. */
 453                error = -E2BIG;
 454        }
 455        kfree(kvalue);
 456        return error;
 457}
 458
 459SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
 460                const char __user *, name, void __user *, value, size_t, size)
 461{
 462        struct path path;
 463        ssize_t error;
 464
 465        error = user_path(pathname, &path);
 466        if (error)
 467                return error;
 468        error = getxattr(path.dentry, name, value, size);
 469        path_put(&path);
 470        return error;
 471}
 472
 473SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
 474                const char __user *, name, void __user *, value, size_t, size)
 475{
 476        struct path path;
 477        ssize_t error;
 478
 479        error = user_lpath(pathname, &path);
 480        if (error)
 481                return error;
 482        error = getxattr(path.dentry, name, value, size);
 483        path_put(&path);
 484        return error;
 485}
 486
 487SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
 488                void __user *, value, size_t, size)
 489{
 490        int fput_needed;
 491        struct file *f;
 492        ssize_t error = -EBADF;
 493
 494        f = fget_light(fd, &fput_needed);
 495        if (!f)
 496                return error;
 497        audit_inode(NULL, f->f_path.dentry);
 498        error = getxattr(f->f_path.dentry, name, value, size);
 499        fput_light(f, fput_needed);
 500        return error;
 501}
 502
 503/*
 504 * Extended attribute LIST operations
 505 */
 506static ssize_t
 507listxattr(struct dentry *d, char __user *list, size_t size)
 508{
 509        ssize_t error;
 510        char *klist = NULL;
 511        char *vlist = NULL;     /* If non-NULL, we used vmalloc() */
 512
 513        if (size) {
 514                if (size > XATTR_LIST_MAX)
 515                        size = XATTR_LIST_MAX;
 516                klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL);
 517                if (!klist) {
 518                        vlist = vmalloc(size);
 519                        if (!vlist)
 520                                return -ENOMEM;
 521                        klist = vlist;
 522                }
 523        }
 524
 525        error = vfs_listxattr(d, klist, size);
 526        if (error > 0) {
 527                if (size && copy_to_user(list, klist, error))
 528                        error = -EFAULT;
 529        } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
 530                /* The file system tried to returned a list bigger
 531                   than XATTR_LIST_MAX bytes. Not possible. */
 532                error = -E2BIG;
 533        }
 534        if (vlist)
 535                vfree(vlist);
 536        else
 537                kfree(klist);
 538        return error;
 539}
 540
 541SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
 542                size_t, size)
 543{
 544        struct path path;
 545        ssize_t error;
 546
 547        error = user_path(pathname, &path);
 548        if (error)
 549                return error;
 550        error = listxattr(path.dentry, list, size);
 551        path_put(&path);
 552        return error;
 553}
 554
 555SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
 556                size_t, size)
 557{
 558        struct path path;
 559        ssize_t error;
 560
 561        error = user_lpath(pathname, &path);
 562        if (error)
 563                return error;
 564        error = listxattr(path.dentry, list, size);
 565        path_put(&path);
 566        return error;
 567}
 568
 569SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
 570{
 571        int fput_needed;
 572        struct file *f;
 573        ssize_t error = -EBADF;
 574
 575        f = fget_light(fd, &fput_needed);
 576        if (!f)
 577                return error;
 578        audit_inode(NULL, f->f_path.dentry);
 579        error = listxattr(f->f_path.dentry, list, size);
 580        fput_light(f, fput_needed);
 581        return error;
 582}
 583
 584/*
 585 * Extended attribute REMOVE operations
 586 */
 587static long
 588removexattr(struct dentry *d, const char __user *name)
 589{
 590        int error;
 591        char kname[XATTR_NAME_MAX + 1];
 592
 593        error = strncpy_from_user(kname, name, sizeof(kname));
 594        if (error == 0 || error == sizeof(kname))
 595                error = -ERANGE;
 596        if (error < 0)
 597                return error;
 598
 599        return vfs_removexattr(d, kname);
 600}
 601
 602SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
 603                const char __user *, name)
 604{
 605        struct path path;
 606        int error;
 607
 608        error = user_path(pathname, &path);
 609        if (error)
 610                return error;
 611        error = mnt_want_write(path.mnt);
 612        if (!error) {
 613                error = removexattr(path.dentry, name);
 614                mnt_drop_write(path.mnt);
 615        }
 616        path_put(&path);
 617        return error;
 618}
 619
 620SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
 621                const char __user *, name)
 622{
 623        struct path path;
 624        int error;
 625
 626        error = user_lpath(pathname, &path);
 627        if (error)
 628                return error;
 629        error = mnt_want_write(path.mnt);
 630        if (!error) {
 631                error = removexattr(path.dentry, name);
 632                mnt_drop_write(path.mnt);
 633        }
 634        path_put(&path);
 635        return error;
 636}
 637
 638SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
 639{
 640        int fput_needed;
 641        struct file *f;
 642        struct dentry *dentry;
 643        int error = -EBADF;
 644
 645        f = fget_light(fd, &fput_needed);
 646        if (!f)
 647                return error;
 648        dentry = f->f_path.dentry;
 649        audit_inode(NULL, dentry);
 650        error = mnt_want_write_file(f);
 651        if (!error) {
 652                error = removexattr(dentry, name);
 653                mnt_drop_write_file(f);
 654        }
 655        fput_light(f, fput_needed);
 656        return error;
 657}
 658
 659
 660static const char *
 661strcmp_prefix(const char *a, const char *a_prefix)
 662{
 663        while (*a_prefix && *a == *a_prefix) {
 664                a++;
 665                a_prefix++;
 666        }
 667        return *a_prefix ? NULL : a;
 668}
 669
 670/*
 671 * In order to implement different sets of xattr operations for each xattr
 672 * prefix with the generic xattr API, a filesystem should create a
 673 * null-terminated array of struct xattr_handler (one for each prefix) and
 674 * hang a pointer to it off of the s_xattr field of the superblock.
 675 *
 676 * The generic_fooxattr() functions will use this list to dispatch xattr
 677 * operations to the correct xattr_handler.
 678 */
 679#define for_each_xattr_handler(handlers, handler)               \
 680                for ((handler) = *(handlers)++;                 \
 681                        (handler) != NULL;                      \
 682                        (handler) = *(handlers)++)
 683
 684/*
 685 * Find the xattr_handler with the matching prefix.
 686 */
 687static const struct xattr_handler *
 688xattr_resolve_name(const struct xattr_handler **handlers, const char **name)
 689{
 690        const struct xattr_handler *handler;
 691
 692        if (!*name)
 693                return NULL;
 694
 695        for_each_xattr_handler(handlers, handler) {
 696                const char *n = strcmp_prefix(*name, handler->prefix);
 697                if (n) {
 698                        *name = n;
 699                        break;
 700                }
 701        }
 702        return handler;
 703}
 704
 705/*
 706 * Find the handler for the prefix and dispatch its get() operation.
 707 */
 708ssize_t
 709generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
 710{
 711        const struct xattr_handler *handler;
 712
 713        handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
 714        if (!handler)
 715                return -EOPNOTSUPP;
 716        return handler->get(dentry, name, buffer, size, handler->flags);
 717}
 718
 719/*
 720 * Combine the results of the list() operation from every xattr_handler in the
 721 * list.
 722 */
 723ssize_t
 724generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 725{
 726        const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
 727        unsigned int size = 0;
 728
 729        if (!buffer) {
 730                for_each_xattr_handler(handlers, handler) {
 731                        size += handler->list(dentry, NULL, 0, NULL, 0,
 732                                              handler->flags);
 733                }
 734        } else {
 735                char *buf = buffer;
 736
 737                for_each_xattr_handler(handlers, handler) {
 738                        size = handler->list(dentry, buf, buffer_size,
 739                                             NULL, 0, handler->flags);
 740                        if (size > buffer_size)
 741                                return -ERANGE;
 742                        buf += size;
 743                        buffer_size -= size;
 744                }
 745                size = buf - buffer;
 746        }
 747        return size;
 748}
 749
 750/*
 751 * Find the handler for the prefix and dispatch its set() operation.
 752 */
 753int
 754generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
 755{
 756        const struct xattr_handler *handler;
 757
 758        if (size == 0)
 759                value = "";  /* empty EA, do not remove */
 760        handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
 761        if (!handler)
 762                return -EOPNOTSUPP;
 763        return handler->set(dentry, name, value, size, flags, handler->flags);
 764}
 765
 766/*
 767 * Find the handler for the prefix and dispatch its set() operation to remove
 768 * any associated extended attribute.
 769 */
 770int
 771generic_removexattr(struct dentry *dentry, const char *name)
 772{
 773        const struct xattr_handler *handler;
 774
 775        handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
 776        if (!handler)
 777                return -EOPNOTSUPP;
 778        return handler->set(dentry, name, NULL, 0,
 779                            XATTR_REPLACE, handler->flags);
 780}
 781
 782EXPORT_SYMBOL(generic_getxattr);
 783EXPORT_SYMBOL(generic_listxattr);
 784EXPORT_SYMBOL(generic_setxattr);
 785EXPORT_SYMBOL(generic_removexattr);
 786
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