xref: /openbmc/linux/fs/xattr.c (revision 95e9fd10) 
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  */
30 static int
31 xattr_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  */
91 int __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 
120 int
121 vfs_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 
138 out:
139 	mutex_unlock(&inode->i_mutex);
140 	return error;
141 }
142 EXPORT_SYMBOL_GPL(vfs_setxattr);
143 
144 ssize_t
145 xattr_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);
164 out:
165 	security_release_secctx(buffer, len);
166 out_noalloc:
167 	return len;
168 }
169 EXPORT_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  */
179 ssize_t
180 vfs_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 */
211 int 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 
229 ssize_t
230 vfs_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 	}
255 nolsm:
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 }
263 EXPORT_SYMBOL_GPL(vfs_getxattr);
264 
265 ssize_t
266 vfs_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 }
283 EXPORT_SYMBOL_GPL(vfs_listxattr);
284 
285 int
286 vfs_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 }
312 EXPORT_SYMBOL_GPL(vfs_removexattr);
313 
314 
315 /*
316  * Extended attribute SET operations
317  */
318 static long
319 setxattr(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);
353 out:
354 	if (vvalue)
355 		vfree(vvalue);
356 	else
357 		kfree(kvalue);
358 	return error;
359 }
360 
361 SYSCALL_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 
380 SYSCALL_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 
399 SYSCALL_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  */
424 static ssize_t
425 getxattr(struct dentry *d, const char __user *name, void __user *value,
426 	 size_t size)
427 {
428 	ssize_t error;
429 	void *kvalue = NULL;
430 	void *vvalue = NULL;
431 	char kname[XATTR_NAME_MAX + 1];
432 
433 	error = strncpy_from_user(kname, name, sizeof(kname));
434 	if (error == 0 || error == sizeof(kname))
435 		error = -ERANGE;
436 	if (error < 0)
437 		return error;
438 
439 	if (size) {
440 		if (size > XATTR_SIZE_MAX)
441 			size = XATTR_SIZE_MAX;
442 		kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
443 		if (!kvalue) {
444 			vvalue = vmalloc(size);
445 			if (!vvalue)
446 				return -ENOMEM;
447 			kvalue = vvalue;
448 		}
449 	}
450 
451 	error = vfs_getxattr(d, kname, kvalue, size);
452 	if (error > 0) {
453 		if (size && copy_to_user(value, kvalue, error))
454 			error = -EFAULT;
455 	} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
456 		/* The file system tried to returned a value bigger
457 		   than XATTR_SIZE_MAX bytes. Not possible. */
458 		error = -E2BIG;
459 	}
460 	if (vvalue)
461 		vfree(vvalue);
462 	else
463 		kfree(kvalue);
464 	return error;
465 }
466 
467 SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
468 		const char __user *, name, void __user *, value, size_t, size)
469 {
470 	struct path path;
471 	ssize_t error;
472 
473 	error = user_path(pathname, &path);
474 	if (error)
475 		return error;
476 	error = getxattr(path.dentry, name, value, size);
477 	path_put(&path);
478 	return error;
479 }
480 
481 SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
482 		const char __user *, name, void __user *, value, size_t, size)
483 {
484 	struct path path;
485 	ssize_t error;
486 
487 	error = user_lpath(pathname, &path);
488 	if (error)
489 		return error;
490 	error = getxattr(path.dentry, name, value, size);
491 	path_put(&path);
492 	return error;
493 }
494 
495 SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
496 		void __user *, value, size_t, size)
497 {
498 	int fput_needed;
499 	struct file *f;
500 	ssize_t error = -EBADF;
501 
502 	f = fget_light(fd, &fput_needed);
503 	if (!f)
504 		return error;
505 	audit_inode(NULL, f->f_path.dentry);
506 	error = getxattr(f->f_path.dentry, name, value, size);
507 	fput_light(f, fput_needed);
508 	return error;
509 }
510 
511 /*
512  * Extended attribute LIST operations
513  */
514 static ssize_t
515 listxattr(struct dentry *d, char __user *list, size_t size)
516 {
517 	ssize_t error;
518 	char *klist = NULL;
519 	char *vlist = NULL;	/* If non-NULL, we used vmalloc() */
520 
521 	if (size) {
522 		if (size > XATTR_LIST_MAX)
523 			size = XATTR_LIST_MAX;
524 		klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL);
525 		if (!klist) {
526 			vlist = vmalloc(size);
527 			if (!vlist)
528 				return -ENOMEM;
529 			klist = vlist;
530 		}
531 	}
532 
533 	error = vfs_listxattr(d, klist, size);
534 	if (error > 0) {
535 		if (size && copy_to_user(list, klist, error))
536 			error = -EFAULT;
537 	} else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
538 		/* The file system tried to returned a list bigger
539 		   than XATTR_LIST_MAX bytes. Not possible. */
540 		error = -E2BIG;
541 	}
542 	if (vlist)
543 		vfree(vlist);
544 	else
545 		kfree(klist);
546 	return error;
547 }
548 
549 SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
550 		size_t, size)
551 {
552 	struct path path;
553 	ssize_t error;
554 
555 	error = user_path(pathname, &path);
556 	if (error)
557 		return error;
558 	error = listxattr(path.dentry, list, size);
559 	path_put(&path);
560 	return error;
561 }
562 
563 SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
564 		size_t, size)
565 {
566 	struct path path;
567 	ssize_t error;
568 
569 	error = user_lpath(pathname, &path);
570 	if (error)
571 		return error;
572 	error = listxattr(path.dentry, list, size);
573 	path_put(&path);
574 	return error;
575 }
576 
577 SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
578 {
579 	int fput_needed;
580 	struct file *f;
581 	ssize_t error = -EBADF;
582 
583 	f = fget_light(fd, &fput_needed);
584 	if (!f)
585 		return error;
586 	audit_inode(NULL, f->f_path.dentry);
587 	error = listxattr(f->f_path.dentry, list, size);
588 	fput_light(f, fput_needed);
589 	return error;
590 }
591 
592 /*
593  * Extended attribute REMOVE operations
594  */
595 static long
596 removexattr(struct dentry *d, const char __user *name)
597 {
598 	int error;
599 	char kname[XATTR_NAME_MAX + 1];
600 
601 	error = strncpy_from_user(kname, name, sizeof(kname));
602 	if (error == 0 || error == sizeof(kname))
603 		error = -ERANGE;
604 	if (error < 0)
605 		return error;
606 
607 	return vfs_removexattr(d, kname);
608 }
609 
610 SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
611 		const char __user *, name)
612 {
613 	struct path path;
614 	int error;
615 
616 	error = user_path(pathname, &path);
617 	if (error)
618 		return error;
619 	error = mnt_want_write(path.mnt);
620 	if (!error) {
621 		error = removexattr(path.dentry, name);
622 		mnt_drop_write(path.mnt);
623 	}
624 	path_put(&path);
625 	return error;
626 }
627 
628 SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
629 		const char __user *, name)
630 {
631 	struct path path;
632 	int error;
633 
634 	error = user_lpath(pathname, &path);
635 	if (error)
636 		return error;
637 	error = mnt_want_write(path.mnt);
638 	if (!error) {
639 		error = removexattr(path.dentry, name);
640 		mnt_drop_write(path.mnt);
641 	}
642 	path_put(&path);
643 	return error;
644 }
645 
646 SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
647 {
648 	int fput_needed;
649 	struct file *f;
650 	struct dentry *dentry;
651 	int error = -EBADF;
652 
653 	f = fget_light(fd, &fput_needed);
654 	if (!f)
655 		return error;
656 	dentry = f->f_path.dentry;
657 	audit_inode(NULL, dentry);
658 	error = mnt_want_write_file(f);
659 	if (!error) {
660 		error = removexattr(dentry, name);
661 		mnt_drop_write_file(f);
662 	}
663 	fput_light(f, fput_needed);
664 	return error;
665 }
666 
667 
668 static const char *
669 strcmp_prefix(const char *a, const char *a_prefix)
670 {
671 	while (*a_prefix && *a == *a_prefix) {
672 		a++;
673 		a_prefix++;
674 	}
675 	return *a_prefix ? NULL : a;
676 }
677 
678 /*
679  * In order to implement different sets of xattr operations for each xattr
680  * prefix with the generic xattr API, a filesystem should create a
681  * null-terminated array of struct xattr_handler (one for each prefix) and
682  * hang a pointer to it off of the s_xattr field of the superblock.
683  *
684  * The generic_fooxattr() functions will use this list to dispatch xattr
685  * operations to the correct xattr_handler.
686  */
687 #define for_each_xattr_handler(handlers, handler)		\
688 		for ((handler) = *(handlers)++;			\
689 			(handler) != NULL;			\
690 			(handler) = *(handlers)++)
691 
692 /*
693  * Find the xattr_handler with the matching prefix.
694  */
695 static const struct xattr_handler *
696 xattr_resolve_name(const struct xattr_handler **handlers, const char **name)
697 {
698 	const struct xattr_handler *handler;
699 
700 	if (!*name)
701 		return NULL;
702 
703 	for_each_xattr_handler(handlers, handler) {
704 		const char *n = strcmp_prefix(*name, handler->prefix);
705 		if (n) {
706 			*name = n;
707 			break;
708 		}
709 	}
710 	return handler;
711 }
712 
713 /*
714  * Find the handler for the prefix and dispatch its get() operation.
715  */
716 ssize_t
717 generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
718 {
719 	const struct xattr_handler *handler;
720 
721 	handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
722 	if (!handler)
723 		return -EOPNOTSUPP;
724 	return handler->get(dentry, name, buffer, size, handler->flags);
725 }
726 
727 /*
728  * Combine the results of the list() operation from every xattr_handler in the
729  * list.
730  */
731 ssize_t
732 generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
733 {
734 	const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
735 	unsigned int size = 0;
736 
737 	if (!buffer) {
738 		for_each_xattr_handler(handlers, handler) {
739 			size += handler->list(dentry, NULL, 0, NULL, 0,
740 					      handler->flags);
741 		}
742 	} else {
743 		char *buf = buffer;
744 
745 		for_each_xattr_handler(handlers, handler) {
746 			size = handler->list(dentry, buf, buffer_size,
747 					     NULL, 0, handler->flags);
748 			if (size > buffer_size)
749 				return -ERANGE;
750 			buf += size;
751 			buffer_size -= size;
752 		}
753 		size = buf - buffer;
754 	}
755 	return size;
756 }
757 
758 /*
759  * Find the handler for the prefix and dispatch its set() operation.
760  */
761 int
762 generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
763 {
764 	const struct xattr_handler *handler;
765 
766 	if (size == 0)
767 		value = "";  /* empty EA, do not remove */
768 	handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
769 	if (!handler)
770 		return -EOPNOTSUPP;
771 	return handler->set(dentry, name, value, size, flags, handler->flags);
772 }
773 
774 /*
775  * Find the handler for the prefix and dispatch its set() operation to remove
776  * any associated extended attribute.
777  */
778 int
779 generic_removexattr(struct dentry *dentry, const char *name)
780 {
781 	const struct xattr_handler *handler;
782 
783 	handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
784 	if (!handler)
785 		return -EOPNOTSUPP;
786 	return handler->set(dentry, name, NULL, 0,
787 			    XATTR_REPLACE, handler->flags);
788 }
789 
790 EXPORT_SYMBOL(generic_getxattr);
791 EXPORT_SYMBOL(generic_listxattr);
792 EXPORT_SYMBOL(generic_setxattr);
793 EXPORT_SYMBOL(generic_removexattr);
794