Loading...
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 File: fs/xattr.c
4
5 Extended attribute handling.
6
7 Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
8 Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
9 Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
10 */
11#include <linux/fs.h>
12#include <linux/slab.h>
13#include <linux/file.h>
14#include <linux/xattr.h>
15#include <linux/mount.h>
16#include <linux/namei.h>
17#include <linux/security.h>
18#include <linux/evm.h>
19#include <linux/syscalls.h>
20#include <linux/export.h>
21#include <linux/fsnotify.h>
22#include <linux/audit.h>
23#include <linux/vmalloc.h>
24#include <linux/posix_acl_xattr.h>
25
26#include <linux/uaccess.h>
27
28#include "internal.h"
29
30static const char *
31strcmp_prefix(const char *a, const char *a_prefix)
32{
33 while (*a_prefix && *a == *a_prefix) {
34 a++;
35 a_prefix++;
36 }
37 return *a_prefix ? NULL : a;
38}
39
40/*
41 * In order to implement different sets of xattr operations for each xattr
42 * prefix, a filesystem should create a null-terminated array of struct
43 * xattr_handler (one for each prefix) and hang a pointer to it off of the
44 * s_xattr field of the superblock.
45 */
46#define for_each_xattr_handler(handlers, handler) \
47 if (handlers) \
48 for ((handler) = *(handlers)++; \
49 (handler) != NULL; \
50 (handler) = *(handlers)++)
51
52/*
53 * Find the xattr_handler with the matching prefix.
54 */
55static const struct xattr_handler *
56xattr_resolve_name(struct inode *inode, const char **name)
57{
58 const struct xattr_handler **handlers = inode->i_sb->s_xattr;
59 const struct xattr_handler *handler;
60
61 if (!(inode->i_opflags & IOP_XATTR)) {
62 if (unlikely(is_bad_inode(inode)))
63 return ERR_PTR(-EIO);
64 return ERR_PTR(-EOPNOTSUPP);
65 }
66 for_each_xattr_handler(handlers, handler) {
67 const char *n;
68
69 n = strcmp_prefix(*name, xattr_prefix(handler));
70 if (n) {
71 if (!handler->prefix ^ !*n) {
72 if (*n)
73 continue;
74 return ERR_PTR(-EINVAL);
75 }
76 *name = n;
77 return handler;
78 }
79 }
80 return ERR_PTR(-EOPNOTSUPP);
81}
82
83/**
84 * may_write_xattr - check whether inode allows writing xattr
85 * @mnt_userns: User namespace of the mount the inode was found from
86 * @inode: the inode on which to set an xattr
87 *
88 * Check whether the inode allows writing xattrs. Specifically, we can never
89 * set or remove an extended attribute on a read-only filesystem or on an
90 * immutable / append-only inode.
91 *
92 * We also need to ensure that the inode has a mapping in the mount to
93 * not risk writing back invalid i_{g,u}id values.
94 *
95 * Return: On success zero is returned. On error a negative errno is returned.
96 */
97int may_write_xattr(struct user_namespace *mnt_userns, struct inode *inode)
98{
99 if (IS_IMMUTABLE(inode))
100 return -EPERM;
101 if (IS_APPEND(inode))
102 return -EPERM;
103 if (HAS_UNMAPPED_ID(mnt_userns, inode))
104 return -EPERM;
105 return 0;
106}
107
108/*
109 * Check permissions for extended attribute access. This is a bit complicated
110 * because different namespaces have very different rules.
111 */
112static int
113xattr_permission(struct user_namespace *mnt_userns, struct inode *inode,
114 const char *name, int mask)
115{
116 if (mask & MAY_WRITE) {
117 int ret;
118
119 ret = may_write_xattr(mnt_userns, inode);
120 if (ret)
121 return ret;
122 }
123
124 /*
125 * No restriction for security.* and system.* from the VFS. Decision
126 * on these is left to the underlying filesystem / security module.
127 */
128 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
129 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
130 return 0;
131
132 /*
133 * The trusted.* namespace can only be accessed by privileged users.
134 */
135 if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
136 if (!capable(CAP_SYS_ADMIN))
137 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
138 return 0;
139 }
140
141 /*
142 * In the user.* namespace, only regular files and directories can have
143 * extended attributes. For sticky directories, only the owner and
144 * privileged users can write attributes.
145 */
146 if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
147 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
148 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
149 if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
150 (mask & MAY_WRITE) &&
151 !inode_owner_or_capable(mnt_userns, inode))
152 return -EPERM;
153 }
154
155 return inode_permission(mnt_userns, inode, mask);
156}
157
158/*
159 * Look for any handler that deals with the specified namespace.
160 */
161int
162xattr_supported_namespace(struct inode *inode, const char *prefix)
163{
164 const struct xattr_handler **handlers = inode->i_sb->s_xattr;
165 const struct xattr_handler *handler;
166 size_t preflen;
167
168 if (!(inode->i_opflags & IOP_XATTR)) {
169 if (unlikely(is_bad_inode(inode)))
170 return -EIO;
171 return -EOPNOTSUPP;
172 }
173
174 preflen = strlen(prefix);
175
176 for_each_xattr_handler(handlers, handler) {
177 if (!strncmp(xattr_prefix(handler), prefix, preflen))
178 return 0;
179 }
180
181 return -EOPNOTSUPP;
182}
183EXPORT_SYMBOL(xattr_supported_namespace);
184
185int
186__vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
187 struct inode *inode, const char *name, const void *value,
188 size_t size, int flags)
189{
190 const struct xattr_handler *handler;
191
192 if (is_posix_acl_xattr(name))
193 return -EOPNOTSUPP;
194
195 handler = xattr_resolve_name(inode, &name);
196 if (IS_ERR(handler))
197 return PTR_ERR(handler);
198 if (!handler->set)
199 return -EOPNOTSUPP;
200 if (size == 0)
201 value = ""; /* empty EA, do not remove */
202 return handler->set(handler, mnt_userns, dentry, inode, name, value,
203 size, flags);
204}
205EXPORT_SYMBOL(__vfs_setxattr);
206
207/**
208 * __vfs_setxattr_noperm - perform setxattr operation without performing
209 * permission checks.
210 *
211 * @mnt_userns: user namespace of the mount the inode was found from
212 * @dentry: object to perform setxattr on
213 * @name: xattr name to set
214 * @value: value to set @name to
215 * @size: size of @value
216 * @flags: flags to pass into filesystem operations
217 *
218 * returns the result of the internal setxattr or setsecurity operations.
219 *
220 * This function requires the caller to lock the inode's i_mutex before it
221 * is executed. It also assumes that the caller will make the appropriate
222 * permission checks.
223 */
224int __vfs_setxattr_noperm(struct user_namespace *mnt_userns,
225 struct dentry *dentry, const char *name,
226 const void *value, size_t size, int flags)
227{
228 struct inode *inode = dentry->d_inode;
229 int error = -EAGAIN;
230 int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
231 XATTR_SECURITY_PREFIX_LEN);
232
233 if (issec)
234 inode->i_flags &= ~S_NOSEC;
235 if (inode->i_opflags & IOP_XATTR) {
236 error = __vfs_setxattr(mnt_userns, dentry, inode, name, value,
237 size, flags);
238 if (!error) {
239 fsnotify_xattr(dentry);
240 security_inode_post_setxattr(dentry, name, value,
241 size, flags);
242 }
243 } else {
244 if (unlikely(is_bad_inode(inode)))
245 return -EIO;
246 }
247 if (error == -EAGAIN) {
248 error = -EOPNOTSUPP;
249
250 if (issec) {
251 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
252
253 error = security_inode_setsecurity(inode, suffix, value,
254 size, flags);
255 if (!error)
256 fsnotify_xattr(dentry);
257 }
258 }
259
260 return error;
261}
262
263/**
264 * __vfs_setxattr_locked - set an extended attribute while holding the inode
265 * lock
266 *
267 * @mnt_userns: user namespace of the mount of the target inode
268 * @dentry: object to perform setxattr on
269 * @name: xattr name to set
270 * @value: value to set @name to
271 * @size: size of @value
272 * @flags: flags to pass into filesystem operations
273 * @delegated_inode: on return, will contain an inode pointer that
274 * a delegation was broken on, NULL if none.
275 */
276int
277__vfs_setxattr_locked(struct user_namespace *mnt_userns, struct dentry *dentry,
278 const char *name, const void *value, size_t size,
279 int flags, struct inode **delegated_inode)
280{
281 struct inode *inode = dentry->d_inode;
282 int error;
283
284 error = xattr_permission(mnt_userns, inode, name, MAY_WRITE);
285 if (error)
286 return error;
287
288 error = security_inode_setxattr(mnt_userns, dentry, name, value, size,
289 flags);
290 if (error)
291 goto out;
292
293 error = try_break_deleg(inode, delegated_inode);
294 if (error)
295 goto out;
296
297 error = __vfs_setxattr_noperm(mnt_userns, dentry, name, value,
298 size, flags);
299
300out:
301 return error;
302}
303EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
304
305int
306vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
307 const char *name, const void *value, size_t size, int flags)
308{
309 struct inode *inode = dentry->d_inode;
310 struct inode *delegated_inode = NULL;
311 const void *orig_value = value;
312 int error;
313
314 if (size && strcmp(name, XATTR_NAME_CAPS) == 0) {
315 error = cap_convert_nscap(mnt_userns, dentry, &value, size);
316 if (error < 0)
317 return error;
318 size = error;
319 }
320
321retry_deleg:
322 inode_lock(inode);
323 error = __vfs_setxattr_locked(mnt_userns, dentry, name, value, size,
324 flags, &delegated_inode);
325 inode_unlock(inode);
326
327 if (delegated_inode) {
328 error = break_deleg_wait(&delegated_inode);
329 if (!error)
330 goto retry_deleg;
331 }
332 if (value != orig_value)
333 kfree(value);
334
335 return error;
336}
337EXPORT_SYMBOL_GPL(vfs_setxattr);
338
339static ssize_t
340xattr_getsecurity(struct user_namespace *mnt_userns, struct inode *inode,
341 const char *name, void *value, size_t size)
342{
343 void *buffer = NULL;
344 ssize_t len;
345
346 if (!value || !size) {
347 len = security_inode_getsecurity(mnt_userns, inode, name,
348 &buffer, false);
349 goto out_noalloc;
350 }
351
352 len = security_inode_getsecurity(mnt_userns, inode, name, &buffer,
353 true);
354 if (len < 0)
355 return len;
356 if (size < len) {
357 len = -ERANGE;
358 goto out;
359 }
360 memcpy(value, buffer, len);
361out:
362 kfree(buffer);
363out_noalloc:
364 return len;
365}
366
367/*
368 * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
369 *
370 * Allocate memory, if not already allocated, or re-allocate correct size,
371 * before retrieving the extended attribute. The xattr value buffer should
372 * always be freed by the caller, even on error.
373 *
374 * Returns the result of alloc, if failed, or the getxattr operation.
375 */
376int
377vfs_getxattr_alloc(struct user_namespace *mnt_userns, struct dentry *dentry,
378 const char *name, char **xattr_value, size_t xattr_size,
379 gfp_t flags)
380{
381 const struct xattr_handler *handler;
382 struct inode *inode = dentry->d_inode;
383 char *value = *xattr_value;
384 int error;
385
386 error = xattr_permission(mnt_userns, inode, name, MAY_READ);
387 if (error)
388 return error;
389
390 handler = xattr_resolve_name(inode, &name);
391 if (IS_ERR(handler))
392 return PTR_ERR(handler);
393 if (!handler->get)
394 return -EOPNOTSUPP;
395 error = handler->get(handler, dentry, inode, name, NULL, 0);
396 if (error < 0)
397 return error;
398
399 if (!value || (error > xattr_size)) {
400 value = krealloc(*xattr_value, error + 1, flags);
401 if (!value)
402 return -ENOMEM;
403 memset(value, 0, error + 1);
404 }
405
406 error = handler->get(handler, dentry, inode, name, value, error);
407 *xattr_value = value;
408 return error;
409}
410
411ssize_t
412__vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
413 void *value, size_t size)
414{
415 const struct xattr_handler *handler;
416
417 if (is_posix_acl_xattr(name))
418 return -EOPNOTSUPP;
419
420 handler = xattr_resolve_name(inode, &name);
421 if (IS_ERR(handler))
422 return PTR_ERR(handler);
423 if (!handler->get)
424 return -EOPNOTSUPP;
425 return handler->get(handler, dentry, inode, name, value, size);
426}
427EXPORT_SYMBOL(__vfs_getxattr);
428
429ssize_t
430vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
431 const char *name, void *value, size_t size)
432{
433 struct inode *inode = dentry->d_inode;
434 int error;
435
436 error = xattr_permission(mnt_userns, inode, name, MAY_READ);
437 if (error)
438 return error;
439
440 error = security_inode_getxattr(dentry, name);
441 if (error)
442 return error;
443
444 if (!strncmp(name, XATTR_SECURITY_PREFIX,
445 XATTR_SECURITY_PREFIX_LEN)) {
446 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
447 int ret = xattr_getsecurity(mnt_userns, inode, suffix, value,
448 size);
449 /*
450 * Only overwrite the return value if a security module
451 * is actually active.
452 */
453 if (ret == -EOPNOTSUPP)
454 goto nolsm;
455 return ret;
456 }
457nolsm:
458 return __vfs_getxattr(dentry, inode, name, value, size);
459}
460EXPORT_SYMBOL_GPL(vfs_getxattr);
461
462ssize_t
463vfs_listxattr(struct dentry *dentry, char *list, size_t size)
464{
465 struct inode *inode = d_inode(dentry);
466 ssize_t error;
467
468 error = security_inode_listxattr(dentry);
469 if (error)
470 return error;
471 if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) {
472 error = inode->i_op->listxattr(dentry, list, size);
473 } else {
474 error = security_inode_listsecurity(inode, list, size);
475 if (size && error > size)
476 error = -ERANGE;
477 }
478 return error;
479}
480EXPORT_SYMBOL_GPL(vfs_listxattr);
481
482int
483__vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
484 const char *name)
485{
486 struct inode *inode = d_inode(dentry);
487 const struct xattr_handler *handler;
488
489 if (is_posix_acl_xattr(name))
490 return -EOPNOTSUPP;
491
492 handler = xattr_resolve_name(inode, &name);
493 if (IS_ERR(handler))
494 return PTR_ERR(handler);
495 if (!handler->set)
496 return -EOPNOTSUPP;
497 return handler->set(handler, mnt_userns, dentry, inode, name, NULL, 0,
498 XATTR_REPLACE);
499}
500EXPORT_SYMBOL(__vfs_removexattr);
501
502/**
503 * __vfs_removexattr_locked - set an extended attribute while holding the inode
504 * lock
505 *
506 * @mnt_userns: user namespace of the mount of the target inode
507 * @dentry: object to perform setxattr on
508 * @name: name of xattr to remove
509 * @delegated_inode: on return, will contain an inode pointer that
510 * a delegation was broken on, NULL if none.
511 */
512int
513__vfs_removexattr_locked(struct user_namespace *mnt_userns,
514 struct dentry *dentry, const char *name,
515 struct inode **delegated_inode)
516{
517 struct inode *inode = dentry->d_inode;
518 int error;
519
520 error = xattr_permission(mnt_userns, inode, name, MAY_WRITE);
521 if (error)
522 return error;
523
524 error = security_inode_removexattr(mnt_userns, dentry, name);
525 if (error)
526 goto out;
527
528 error = try_break_deleg(inode, delegated_inode);
529 if (error)
530 goto out;
531
532 error = __vfs_removexattr(mnt_userns, dentry, name);
533
534 if (!error) {
535 fsnotify_xattr(dentry);
536 evm_inode_post_removexattr(dentry, name);
537 }
538
539out:
540 return error;
541}
542EXPORT_SYMBOL_GPL(__vfs_removexattr_locked);
543
544int
545vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
546 const char *name)
547{
548 struct inode *inode = dentry->d_inode;
549 struct inode *delegated_inode = NULL;
550 int error;
551
552retry_deleg:
553 inode_lock(inode);
554 error = __vfs_removexattr_locked(mnt_userns, dentry,
555 name, &delegated_inode);
556 inode_unlock(inode);
557
558 if (delegated_inode) {
559 error = break_deleg_wait(&delegated_inode);
560 if (!error)
561 goto retry_deleg;
562 }
563
564 return error;
565}
566EXPORT_SYMBOL_GPL(vfs_removexattr);
567
568/*
569 * Extended attribute SET operations
570 */
571
572int setxattr_copy(const char __user *name, struct xattr_ctx *ctx)
573{
574 int error;
575
576 if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
577 return -EINVAL;
578
579 error = strncpy_from_user(ctx->kname->name, name,
580 sizeof(ctx->kname->name));
581 if (error == 0 || error == sizeof(ctx->kname->name))
582 return -ERANGE;
583 if (error < 0)
584 return error;
585
586 error = 0;
587 if (ctx->size) {
588 if (ctx->size > XATTR_SIZE_MAX)
589 return -E2BIG;
590
591 ctx->kvalue = vmemdup_user(ctx->cvalue, ctx->size);
592 if (IS_ERR(ctx->kvalue)) {
593 error = PTR_ERR(ctx->kvalue);
594 ctx->kvalue = NULL;
595 }
596 }
597
598 return error;
599}
600
601int do_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
602 struct xattr_ctx *ctx)
603{
604 if (is_posix_acl_xattr(ctx->kname->name))
605 return do_set_acl(idmap, dentry, ctx->kname->name,
606 ctx->kvalue, ctx->size);
607
608 return vfs_setxattr(mnt_idmap_owner(idmap), dentry, ctx->kname->name,
609 ctx->kvalue, ctx->size, ctx->flags);
610}
611
612static long
613setxattr(struct mnt_idmap *idmap, struct dentry *d,
614 const char __user *name, const void __user *value, size_t size,
615 int flags)
616{
617 struct xattr_name kname;
618 struct xattr_ctx ctx = {
619 .cvalue = value,
620 .kvalue = NULL,
621 .size = size,
622 .kname = &kname,
623 .flags = flags,
624 };
625 int error;
626
627 error = setxattr_copy(name, &ctx);
628 if (error)
629 return error;
630
631 error = do_setxattr(idmap, d, &ctx);
632
633 kvfree(ctx.kvalue);
634 return error;
635}
636
637static int path_setxattr(const char __user *pathname,
638 const char __user *name, const void __user *value,
639 size_t size, int flags, unsigned int lookup_flags)
640{
641 struct path path;
642 int error;
643
644retry:
645 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
646 if (error)
647 return error;
648 error = mnt_want_write(path.mnt);
649 if (!error) {
650 error = setxattr(mnt_idmap(path.mnt), path.dentry, name,
651 value, size, flags);
652 mnt_drop_write(path.mnt);
653 }
654 path_put(&path);
655 if (retry_estale(error, lookup_flags)) {
656 lookup_flags |= LOOKUP_REVAL;
657 goto retry;
658 }
659 return error;
660}
661
662SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
663 const char __user *, name, const void __user *, value,
664 size_t, size, int, flags)
665{
666 return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW);
667}
668
669SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
670 const char __user *, name, const void __user *, value,
671 size_t, size, int, flags)
672{
673 return path_setxattr(pathname, name, value, size, flags, 0);
674}
675
676SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
677 const void __user *,value, size_t, size, int, flags)
678{
679 struct fd f = fdget(fd);
680 int error = -EBADF;
681
682 if (!f.file)
683 return error;
684 audit_file(f.file);
685 error = mnt_want_write_file(f.file);
686 if (!error) {
687 error = setxattr(file_mnt_idmap(f.file),
688 f.file->f_path.dentry, name,
689 value, size, flags);
690 mnt_drop_write_file(f.file);
691 }
692 fdput(f);
693 return error;
694}
695
696/*
697 * Extended attribute GET operations
698 */
699ssize_t
700do_getxattr(struct mnt_idmap *idmap, struct dentry *d,
701 struct xattr_ctx *ctx)
702{
703 ssize_t error;
704 char *kname = ctx->kname->name;
705
706 if (ctx->size) {
707 if (ctx->size > XATTR_SIZE_MAX)
708 ctx->size = XATTR_SIZE_MAX;
709 ctx->kvalue = kvzalloc(ctx->size, GFP_KERNEL);
710 if (!ctx->kvalue)
711 return -ENOMEM;
712 }
713
714 if (is_posix_acl_xattr(ctx->kname->name))
715 error = do_get_acl(idmap, d, kname, ctx->kvalue, ctx->size);
716 else
717 error = vfs_getxattr(mnt_idmap_owner(idmap), d, kname,
718 ctx->kvalue, ctx->size);
719 if (error > 0) {
720 if (ctx->size && copy_to_user(ctx->value, ctx->kvalue, error))
721 error = -EFAULT;
722 } else if (error == -ERANGE && ctx->size >= XATTR_SIZE_MAX) {
723 /* The file system tried to returned a value bigger
724 than XATTR_SIZE_MAX bytes. Not possible. */
725 error = -E2BIG;
726 }
727
728 return error;
729}
730
731static ssize_t
732getxattr(struct mnt_idmap *idmap, struct dentry *d,
733 const char __user *name, void __user *value, size_t size)
734{
735 ssize_t error;
736 struct xattr_name kname;
737 struct xattr_ctx ctx = {
738 .value = value,
739 .kvalue = NULL,
740 .size = size,
741 .kname = &kname,
742 .flags = 0,
743 };
744
745 error = strncpy_from_user(kname.name, name, sizeof(kname.name));
746 if (error == 0 || error == sizeof(kname.name))
747 error = -ERANGE;
748 if (error < 0)
749 return error;
750
751 error = do_getxattr(idmap, d, &ctx);
752
753 kvfree(ctx.kvalue);
754 return error;
755}
756
757static ssize_t path_getxattr(const char __user *pathname,
758 const char __user *name, void __user *value,
759 size_t size, unsigned int lookup_flags)
760{
761 struct path path;
762 ssize_t error;
763retry:
764 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
765 if (error)
766 return error;
767 error = getxattr(mnt_idmap(path.mnt), path.dentry, name, value, size);
768 path_put(&path);
769 if (retry_estale(error, lookup_flags)) {
770 lookup_flags |= LOOKUP_REVAL;
771 goto retry;
772 }
773 return error;
774}
775
776SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
777 const char __user *, name, void __user *, value, size_t, size)
778{
779 return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW);
780}
781
782SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
783 const char __user *, name, void __user *, value, size_t, size)
784{
785 return path_getxattr(pathname, name, value, size, 0);
786}
787
788SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
789 void __user *, value, size_t, size)
790{
791 struct fd f = fdget(fd);
792 ssize_t error = -EBADF;
793
794 if (!f.file)
795 return error;
796 audit_file(f.file);
797 error = getxattr(file_mnt_idmap(f.file), f.file->f_path.dentry,
798 name, value, size);
799 fdput(f);
800 return error;
801}
802
803/*
804 * Extended attribute LIST operations
805 */
806static ssize_t
807listxattr(struct dentry *d, char __user *list, size_t size)
808{
809 ssize_t error;
810 char *klist = NULL;
811
812 if (size) {
813 if (size > XATTR_LIST_MAX)
814 size = XATTR_LIST_MAX;
815 klist = kvmalloc(size, GFP_KERNEL);
816 if (!klist)
817 return -ENOMEM;
818 }
819
820 error = vfs_listxattr(d, klist, size);
821 if (error > 0) {
822 if (size && copy_to_user(list, klist, error))
823 error = -EFAULT;
824 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
825 /* The file system tried to returned a list bigger
826 than XATTR_LIST_MAX bytes. Not possible. */
827 error = -E2BIG;
828 }
829
830 kvfree(klist);
831
832 return error;
833}
834
835static ssize_t path_listxattr(const char __user *pathname, char __user *list,
836 size_t size, unsigned int lookup_flags)
837{
838 struct path path;
839 ssize_t error;
840retry:
841 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
842 if (error)
843 return error;
844 error = listxattr(path.dentry, list, size);
845 path_put(&path);
846 if (retry_estale(error, lookup_flags)) {
847 lookup_flags |= LOOKUP_REVAL;
848 goto retry;
849 }
850 return error;
851}
852
853SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
854 size_t, size)
855{
856 return path_listxattr(pathname, list, size, LOOKUP_FOLLOW);
857}
858
859SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
860 size_t, size)
861{
862 return path_listxattr(pathname, list, size, 0);
863}
864
865SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
866{
867 struct fd f = fdget(fd);
868 ssize_t error = -EBADF;
869
870 if (!f.file)
871 return error;
872 audit_file(f.file);
873 error = listxattr(f.file->f_path.dentry, list, size);
874 fdput(f);
875 return error;
876}
877
878/*
879 * Extended attribute REMOVE operations
880 */
881static long
882removexattr(struct mnt_idmap *idmap, struct dentry *d,
883 const char __user *name)
884{
885 int error;
886 char kname[XATTR_NAME_MAX + 1];
887
888 error = strncpy_from_user(kname, name, sizeof(kname));
889 if (error == 0 || error == sizeof(kname))
890 error = -ERANGE;
891 if (error < 0)
892 return error;
893
894 if (is_posix_acl_xattr(kname))
895 return vfs_remove_acl(mnt_idmap_owner(idmap), d, kname);
896
897 return vfs_removexattr(mnt_idmap_owner(idmap), d, kname);
898}
899
900static int path_removexattr(const char __user *pathname,
901 const char __user *name, unsigned int lookup_flags)
902{
903 struct path path;
904 int error;
905retry:
906 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
907 if (error)
908 return error;
909 error = mnt_want_write(path.mnt);
910 if (!error) {
911 error = removexattr(mnt_idmap(path.mnt), path.dentry, name);
912 mnt_drop_write(path.mnt);
913 }
914 path_put(&path);
915 if (retry_estale(error, lookup_flags)) {
916 lookup_flags |= LOOKUP_REVAL;
917 goto retry;
918 }
919 return error;
920}
921
922SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
923 const char __user *, name)
924{
925 return path_removexattr(pathname, name, LOOKUP_FOLLOW);
926}
927
928SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
929 const char __user *, name)
930{
931 return path_removexattr(pathname, name, 0);
932}
933
934SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
935{
936 struct fd f = fdget(fd);
937 int error = -EBADF;
938
939 if (!f.file)
940 return error;
941 audit_file(f.file);
942 error = mnt_want_write_file(f.file);
943 if (!error) {
944 error = removexattr(file_mnt_idmap(f.file),
945 f.file->f_path.dentry, name);
946 mnt_drop_write_file(f.file);
947 }
948 fdput(f);
949 return error;
950}
951
952/*
953 * Combine the results of the list() operation from every xattr_handler in the
954 * list.
955 */
956ssize_t
957generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
958{
959 const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
960 unsigned int size = 0;
961
962 if (!buffer) {
963 for_each_xattr_handler(handlers, handler) {
964 if (!handler->name ||
965 (handler->list && !handler->list(dentry)))
966 continue;
967 size += strlen(handler->name) + 1;
968 }
969 } else {
970 char *buf = buffer;
971 size_t len;
972
973 for_each_xattr_handler(handlers, handler) {
974 if (!handler->name ||
975 (handler->list && !handler->list(dentry)))
976 continue;
977 len = strlen(handler->name);
978 if (len + 1 > buffer_size)
979 return -ERANGE;
980 memcpy(buf, handler->name, len + 1);
981 buf += len + 1;
982 buffer_size -= len + 1;
983 }
984 size = buf - buffer;
985 }
986 return size;
987}
988EXPORT_SYMBOL(generic_listxattr);
989
990/**
991 * xattr_full_name - Compute full attribute name from suffix
992 *
993 * @handler: handler of the xattr_handler operation
994 * @name: name passed to the xattr_handler operation
995 *
996 * The get and set xattr handler operations are called with the remainder of
997 * the attribute name after skipping the handler's prefix: for example, "foo"
998 * is passed to the get operation of a handler with prefix "user." to get
999 * attribute "user.foo". The full name is still "there" in the name though.
1000 *
1001 * Note: the list xattr handler operation when called from the vfs is passed a
1002 * NULL name; some file systems use this operation internally, with varying
1003 * semantics.
1004 */
1005const char *xattr_full_name(const struct xattr_handler *handler,
1006 const char *name)
1007{
1008 size_t prefix_len = strlen(xattr_prefix(handler));
1009
1010 return name - prefix_len;
1011}
1012EXPORT_SYMBOL(xattr_full_name);
1013
1014/**
1015 * free_simple_xattr - free an xattr object
1016 * @xattr: the xattr object
1017 *
1018 * Free the xattr object. Can handle @xattr being NULL.
1019 */
1020static inline void free_simple_xattr(struct simple_xattr *xattr)
1021{
1022 if (xattr)
1023 kfree(xattr->name);
1024 kvfree(xattr);
1025}
1026
1027/**
1028 * simple_xattr_alloc - allocate new xattr object
1029 * @value: value of the xattr object
1030 * @size: size of @value
1031 *
1032 * Allocate a new xattr object and initialize respective members. The caller is
1033 * responsible for handling the name of the xattr.
1034 *
1035 * Return: On success a new xattr object is returned. On failure NULL is
1036 * returned.
1037 */
1038struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
1039{
1040 struct simple_xattr *new_xattr;
1041 size_t len;
1042
1043 /* wrap around? */
1044 len = sizeof(*new_xattr) + size;
1045 if (len < sizeof(*new_xattr))
1046 return NULL;
1047
1048 new_xattr = kvmalloc(len, GFP_KERNEL);
1049 if (!new_xattr)
1050 return NULL;
1051
1052 new_xattr->size = size;
1053 memcpy(new_xattr->value, value, size);
1054 return new_xattr;
1055}
1056
1057/**
1058 * rbtree_simple_xattr_cmp - compare xattr name with current rbtree xattr entry
1059 * @key: xattr name
1060 * @node: current node
1061 *
1062 * Compare the xattr name with the xattr name attached to @node in the rbtree.
1063 *
1064 * Return: Negative value if continuing left, positive if continuing right, 0
1065 * if the xattr attached to @node matches @key.
1066 */
1067static int rbtree_simple_xattr_cmp(const void *key, const struct rb_node *node)
1068{
1069 const char *xattr_name = key;
1070 const struct simple_xattr *xattr;
1071
1072 xattr = rb_entry(node, struct simple_xattr, rb_node);
1073 return strcmp(xattr->name, xattr_name);
1074}
1075
1076/**
1077 * rbtree_simple_xattr_node_cmp - compare two xattr rbtree nodes
1078 * @new_node: new node
1079 * @node: current node
1080 *
1081 * Compare the xattr attached to @new_node with the xattr attached to @node.
1082 *
1083 * Return: Negative value if continuing left, positive if continuing right, 0
1084 * if the xattr attached to @new_node matches the xattr attached to @node.
1085 */
1086static int rbtree_simple_xattr_node_cmp(struct rb_node *new_node,
1087 const struct rb_node *node)
1088{
1089 struct simple_xattr *xattr;
1090 xattr = rb_entry(new_node, struct simple_xattr, rb_node);
1091 return rbtree_simple_xattr_cmp(xattr->name, node);
1092}
1093
1094/**
1095 * simple_xattr_get - get an xattr object
1096 * @xattrs: the header of the xattr object
1097 * @name: the name of the xattr to retrieve
1098 * @buffer: the buffer to store the value into
1099 * @size: the size of @buffer
1100 *
1101 * Try to find and retrieve the xattr object associated with @name.
1102 * If @buffer is provided store the value of @xattr in @buffer
1103 * otherwise just return the length. The size of @buffer is limited
1104 * to XATTR_SIZE_MAX which currently is 65536.
1105 *
1106 * Return: On success the length of the xattr value is returned. On error a
1107 * negative error code is returned.
1108 */
1109int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
1110 void *buffer, size_t size)
1111{
1112 struct simple_xattr *xattr = NULL;
1113 struct rb_node *rbp;
1114 int ret = -ENODATA;
1115
1116 read_lock(&xattrs->lock);
1117 rbp = rb_find(name, &xattrs->rb_root, rbtree_simple_xattr_cmp);
1118 if (rbp) {
1119 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1120 ret = xattr->size;
1121 if (buffer) {
1122 if (size < xattr->size)
1123 ret = -ERANGE;
1124 else
1125 memcpy(buffer, xattr->value, xattr->size);
1126 }
1127 }
1128 read_unlock(&xattrs->lock);
1129 return ret;
1130}
1131
1132/**
1133 * simple_xattr_set - set an xattr object
1134 * @xattrs: the header of the xattr object
1135 * @name: the name of the xattr to retrieve
1136 * @value: the value to store along the xattr
1137 * @size: the size of @value
1138 * @flags: the flags determining how to set the xattr
1139 * @removed_size: the size of the removed xattr
1140 *
1141 * Set a new xattr object.
1142 * If @value is passed a new xattr object will be allocated. If XATTR_REPLACE
1143 * is specified in @flags a matching xattr object for @name must already exist.
1144 * If it does it will be replaced with the new xattr object. If it doesn't we
1145 * fail. If XATTR_CREATE is specified and a matching xattr does already exist
1146 * we fail. If it doesn't we create a new xattr. If @flags is zero we simply
1147 * insert the new xattr replacing any existing one.
1148 *
1149 * If @value is empty and a matching xattr object is found we delete it if
1150 * XATTR_REPLACE is specified in @flags or @flags is zero.
1151 *
1152 * If @value is empty and no matching xattr object for @name is found we do
1153 * nothing if XATTR_CREATE is specified in @flags or @flags is zero. For
1154 * XATTR_REPLACE we fail as mentioned above.
1155 *
1156 * Return: On success zero and on error a negative error code is returned.
1157 */
1158int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
1159 const void *value, size_t size, int flags,
1160 ssize_t *removed_size)
1161{
1162 struct simple_xattr *xattr = NULL, *new_xattr = NULL;
1163 struct rb_node *parent = NULL, **rbp;
1164 int err = 0, ret;
1165
1166 if (removed_size)
1167 *removed_size = -1;
1168
1169 /* value == NULL means remove */
1170 if (value) {
1171 new_xattr = simple_xattr_alloc(value, size);
1172 if (!new_xattr)
1173 return -ENOMEM;
1174
1175 new_xattr->name = kstrdup(name, GFP_KERNEL);
1176 if (!new_xattr->name) {
1177 free_simple_xattr(new_xattr);
1178 return -ENOMEM;
1179 }
1180 }
1181
1182 write_lock(&xattrs->lock);
1183 rbp = &xattrs->rb_root.rb_node;
1184 while (*rbp) {
1185 parent = *rbp;
1186 ret = rbtree_simple_xattr_cmp(name, *rbp);
1187 if (ret < 0)
1188 rbp = &(*rbp)->rb_left;
1189 else if (ret > 0)
1190 rbp = &(*rbp)->rb_right;
1191 else
1192 xattr = rb_entry(*rbp, struct simple_xattr, rb_node);
1193 if (xattr)
1194 break;
1195 }
1196
1197 if (xattr) {
1198 /* Fail if XATTR_CREATE is requested and the xattr exists. */
1199 if (flags & XATTR_CREATE) {
1200 err = -EEXIST;
1201 goto out_unlock;
1202 }
1203
1204 if (new_xattr)
1205 rb_replace_node(&xattr->rb_node, &new_xattr->rb_node,
1206 &xattrs->rb_root);
1207 else
1208 rb_erase(&xattr->rb_node, &xattrs->rb_root);
1209 if (!err && removed_size)
1210 *removed_size = xattr->size;
1211 } else {
1212 /* Fail if XATTR_REPLACE is requested but no xattr is found. */
1213 if (flags & XATTR_REPLACE) {
1214 err = -ENODATA;
1215 goto out_unlock;
1216 }
1217
1218 /*
1219 * If XATTR_CREATE or no flags are specified together with a
1220 * new value simply insert it.
1221 */
1222 if (new_xattr) {
1223 rb_link_node(&new_xattr->rb_node, parent, rbp);
1224 rb_insert_color(&new_xattr->rb_node, &xattrs->rb_root);
1225 }
1226
1227 /*
1228 * If XATTR_CREATE or no flags are specified and neither an
1229 * old or new xattr exist then we don't need to do anything.
1230 */
1231 }
1232
1233out_unlock:
1234 write_unlock(&xattrs->lock);
1235 if (err)
1236 free_simple_xattr(new_xattr);
1237 else
1238 free_simple_xattr(xattr);
1239 return err;
1240
1241}
1242
1243static bool xattr_is_trusted(const char *name)
1244{
1245 return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
1246}
1247
1248static int xattr_list_one(char **buffer, ssize_t *remaining_size,
1249 const char *name)
1250{
1251 size_t len = strlen(name) + 1;
1252 if (*buffer) {
1253 if (*remaining_size < len)
1254 return -ERANGE;
1255 memcpy(*buffer, name, len);
1256 *buffer += len;
1257 }
1258 *remaining_size -= len;
1259 return 0;
1260}
1261
1262/**
1263 * simple_xattr_list - list all xattr objects
1264 * @inode: inode from which to get the xattrs
1265 * @xattrs: the header of the xattr object
1266 * @buffer: the buffer to store all xattrs into
1267 * @size: the size of @buffer
1268 *
1269 * List all xattrs associated with @inode. If @buffer is NULL we returned
1270 * the required size of the buffer. If @buffer is provided we store the
1271 * xattrs value into it provided it is big enough.
1272 *
1273 * Note, the number of xattr names that can be listed with listxattr(2) is
1274 * limited to XATTR_LIST_MAX aka 65536 bytes. If a larger buffer is passed
1275 * then vfs_listxattr() caps it to XATTR_LIST_MAX and if more xattr names
1276 * are found it will return -E2BIG.
1277 *
1278 * Return: On success the required size or the size of the copied xattrs is
1279 * returned. On error a negative error code is returned.
1280 */
1281ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
1282 char *buffer, size_t size)
1283{
1284 bool trusted = ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN);
1285 struct simple_xattr *xattr;
1286 struct rb_node *rbp;
1287 ssize_t remaining_size = size;
1288 int err = 0;
1289
1290#ifdef CONFIG_FS_POSIX_ACL
1291 if (IS_POSIXACL(inode)) {
1292 if (inode->i_acl) {
1293 err = xattr_list_one(&buffer, &remaining_size,
1294 XATTR_NAME_POSIX_ACL_ACCESS);
1295 if (err)
1296 return err;
1297 }
1298 if (inode->i_default_acl) {
1299 err = xattr_list_one(&buffer, &remaining_size,
1300 XATTR_NAME_POSIX_ACL_DEFAULT);
1301 if (err)
1302 return err;
1303 }
1304 }
1305#endif
1306
1307 read_lock(&xattrs->lock);
1308 for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
1309 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1310
1311 /* skip "trusted." attributes for unprivileged callers */
1312 if (!trusted && xattr_is_trusted(xattr->name))
1313 continue;
1314
1315 err = xattr_list_one(&buffer, &remaining_size, xattr->name);
1316 if (err)
1317 break;
1318 }
1319 read_unlock(&xattrs->lock);
1320
1321 return err ? err : size - remaining_size;
1322}
1323
1324/**
1325 * rbtree_simple_xattr_less - compare two xattr rbtree nodes
1326 * @new_node: new node
1327 * @node: current node
1328 *
1329 * Compare the xattr attached to @new_node with the xattr attached to @node.
1330 * Note that this function technically tolerates duplicate entries.
1331 *
1332 * Return: True if insertion point in the rbtree is found.
1333 */
1334static bool rbtree_simple_xattr_less(struct rb_node *new_node,
1335 const struct rb_node *node)
1336{
1337 return rbtree_simple_xattr_node_cmp(new_node, node) < 0;
1338}
1339
1340/**
1341 * simple_xattr_add - add xattr objects
1342 * @xattrs: the header of the xattr object
1343 * @new_xattr: the xattr object to add
1344 *
1345 * Add an xattr object to @xattrs. This assumes no replacement or removal
1346 * of matching xattrs is wanted. Should only be called during inode
1347 * initialization when a few distinct initial xattrs are supposed to be set.
1348 */
1349void simple_xattr_add(struct simple_xattrs *xattrs,
1350 struct simple_xattr *new_xattr)
1351{
1352 write_lock(&xattrs->lock);
1353 rb_add(&new_xattr->rb_node, &xattrs->rb_root, rbtree_simple_xattr_less);
1354 write_unlock(&xattrs->lock);
1355}
1356
1357/**
1358 * simple_xattrs_init - initialize new xattr header
1359 * @xattrs: header to initialize
1360 *
1361 * Initialize relevant fields of a an xattr header.
1362 */
1363void simple_xattrs_init(struct simple_xattrs *xattrs)
1364{
1365 xattrs->rb_root = RB_ROOT;
1366 rwlock_init(&xattrs->lock);
1367}
1368
1369/**
1370 * simple_xattrs_free - free xattrs
1371 * @xattrs: xattr header whose xattrs to destroy
1372 *
1373 * Destroy all xattrs in @xattr. When this is called no one can hold a
1374 * reference to any of the xattrs anymore.
1375 */
1376void simple_xattrs_free(struct simple_xattrs *xattrs)
1377{
1378 struct rb_node *rbp;
1379
1380 rbp = rb_first(&xattrs->rb_root);
1381 while (rbp) {
1382 struct simple_xattr *xattr;
1383 struct rb_node *rbp_next;
1384
1385 rbp_next = rb_next(rbp);
1386 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1387 rb_erase(&xattr->rb_node, &xattrs->rb_root);
1388 free_simple_xattr(xattr);
1389 rbp = rbp_next;
1390 }
1391}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 File: fs/xattr.c
4
5 Extended attribute handling.
6
7 Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
8 Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
9 Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
10 */
11#include <linux/fs.h>
12#include <linux/slab.h>
13#include <linux/file.h>
14#include <linux/xattr.h>
15#include <linux/mount.h>
16#include <linux/namei.h>
17#include <linux/security.h>
18#include <linux/evm.h>
19#include <linux/syscalls.h>
20#include <linux/export.h>
21#include <linux/fsnotify.h>
22#include <linux/audit.h>
23#include <linux/vmalloc.h>
24#include <linux/posix_acl_xattr.h>
25
26#include <linux/uaccess.h>
27
28static const char *
29strcmp_prefix(const char *a, const char *a_prefix)
30{
31 while (*a_prefix && *a == *a_prefix) {
32 a++;
33 a_prefix++;
34 }
35 return *a_prefix ? NULL : a;
36}
37
38/*
39 * In order to implement different sets of xattr operations for each xattr
40 * prefix, a filesystem should create a null-terminated array of struct
41 * xattr_handler (one for each prefix) and hang a pointer to it off of the
42 * s_xattr field of the superblock.
43 */
44#define for_each_xattr_handler(handlers, handler) \
45 if (handlers) \
46 for ((handler) = *(handlers)++; \
47 (handler) != NULL; \
48 (handler) = *(handlers)++)
49
50/*
51 * Find the xattr_handler with the matching prefix.
52 */
53static const struct xattr_handler *
54xattr_resolve_name(struct inode *inode, const char **name)
55{
56 const struct xattr_handler **handlers = inode->i_sb->s_xattr;
57 const struct xattr_handler *handler;
58
59 if (!(inode->i_opflags & IOP_XATTR)) {
60 if (unlikely(is_bad_inode(inode)))
61 return ERR_PTR(-EIO);
62 return ERR_PTR(-EOPNOTSUPP);
63 }
64 for_each_xattr_handler(handlers, handler) {
65 const char *n;
66
67 n = strcmp_prefix(*name, xattr_prefix(handler));
68 if (n) {
69 if (!handler->prefix ^ !*n) {
70 if (*n)
71 continue;
72 return ERR_PTR(-EINVAL);
73 }
74 *name = n;
75 return handler;
76 }
77 }
78 return ERR_PTR(-EOPNOTSUPP);
79}
80
81/*
82 * Check permissions for extended attribute access. This is a bit complicated
83 * because different namespaces have very different rules.
84 */
85static int
86xattr_permission(struct inode *inode, const char *name, int mask)
87{
88 /*
89 * We can never set or remove an extended attribute on a read-only
90 * filesystem or on an immutable / append-only inode.
91 */
92 if (mask & MAY_WRITE) {
93 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
94 return -EPERM;
95 /*
96 * Updating an xattr will likely cause i_uid and i_gid
97 * to be writen back improperly if their true value is
98 * unknown to the vfs.
99 */
100 if (HAS_UNMAPPED_ID(inode))
101 return -EPERM;
102 }
103
104 /*
105 * No restriction for security.* and system.* from the VFS. Decision
106 * on these is left to the underlying filesystem / security module.
107 */
108 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
109 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
110 return 0;
111
112 /*
113 * The trusted.* namespace can only be accessed by privileged users.
114 */
115 if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
116 if (!capable(CAP_SYS_ADMIN))
117 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
118 return 0;
119 }
120
121 /*
122 * In the user.* namespace, only regular files and directories can have
123 * extended attributes. For sticky directories, only the owner and
124 * privileged users can write attributes.
125 */
126 if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
127 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
128 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
129 if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
130 (mask & MAY_WRITE) && !inode_owner_or_capable(inode))
131 return -EPERM;
132 }
133
134 return inode_permission(inode, mask);
135}
136
137/*
138 * Look for any handler that deals with the specified namespace.
139 */
140int
141xattr_supported_namespace(struct inode *inode, const char *prefix)
142{
143 const struct xattr_handler **handlers = inode->i_sb->s_xattr;
144 const struct xattr_handler *handler;
145 size_t preflen;
146
147 if (!(inode->i_opflags & IOP_XATTR)) {
148 if (unlikely(is_bad_inode(inode)))
149 return -EIO;
150 return -EOPNOTSUPP;
151 }
152
153 preflen = strlen(prefix);
154
155 for_each_xattr_handler(handlers, handler) {
156 if (!strncmp(xattr_prefix(handler), prefix, preflen))
157 return 0;
158 }
159
160 return -EOPNOTSUPP;
161}
162EXPORT_SYMBOL(xattr_supported_namespace);
163
164int
165__vfs_setxattr(struct dentry *dentry, struct inode *inode, const char *name,
166 const void *value, size_t size, int flags)
167{
168 const struct xattr_handler *handler;
169
170 handler = xattr_resolve_name(inode, &name);
171 if (IS_ERR(handler))
172 return PTR_ERR(handler);
173 if (!handler->set)
174 return -EOPNOTSUPP;
175 if (size == 0)
176 value = ""; /* empty EA, do not remove */
177 return handler->set(handler, dentry, inode, name, value, size, flags);
178}
179EXPORT_SYMBOL(__vfs_setxattr);
180
181/**
182 * __vfs_setxattr_noperm - perform setxattr operation without performing
183 * permission checks.
184 *
185 * @dentry - object to perform setxattr on
186 * @name - xattr name to set
187 * @value - value to set @name to
188 * @size - size of @value
189 * @flags - flags to pass into filesystem operations
190 *
191 * returns the result of the internal setxattr or setsecurity operations.
192 *
193 * This function requires the caller to lock the inode's i_mutex before it
194 * is executed. It also assumes that the caller will make the appropriate
195 * permission checks.
196 */
197int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
198 const void *value, size_t size, int flags)
199{
200 struct inode *inode = dentry->d_inode;
201 int error = -EAGAIN;
202 int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
203 XATTR_SECURITY_PREFIX_LEN);
204
205 if (issec)
206 inode->i_flags &= ~S_NOSEC;
207 if (inode->i_opflags & IOP_XATTR) {
208 error = __vfs_setxattr(dentry, inode, name, value, size, flags);
209 if (!error) {
210 fsnotify_xattr(dentry);
211 security_inode_post_setxattr(dentry, name, value,
212 size, flags);
213 }
214 } else {
215 if (unlikely(is_bad_inode(inode)))
216 return -EIO;
217 }
218 if (error == -EAGAIN) {
219 error = -EOPNOTSUPP;
220
221 if (issec) {
222 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
223
224 error = security_inode_setsecurity(inode, suffix, value,
225 size, flags);
226 if (!error)
227 fsnotify_xattr(dentry);
228 }
229 }
230
231 return error;
232}
233
234/**
235 * __vfs_setxattr_locked: set an extended attribute while holding the inode
236 * lock
237 *
238 * @dentry - object to perform setxattr on
239 * @name - xattr name to set
240 * @value - value to set @name to
241 * @size - size of @value
242 * @flags - flags to pass into filesystem operations
243 * @delegated_inode - on return, will contain an inode pointer that
244 * a delegation was broken on, NULL if none.
245 */
246int
247__vfs_setxattr_locked(struct dentry *dentry, const char *name,
248 const void *value, size_t size, int flags,
249 struct inode **delegated_inode)
250{
251 struct inode *inode = dentry->d_inode;
252 int error;
253
254 error = xattr_permission(inode, name, MAY_WRITE);
255 if (error)
256 return error;
257
258 error = security_inode_setxattr(dentry, name, value, size, flags);
259 if (error)
260 goto out;
261
262 error = try_break_deleg(inode, delegated_inode);
263 if (error)
264 goto out;
265
266 error = __vfs_setxattr_noperm(dentry, name, value, size, flags);
267
268out:
269 return error;
270}
271EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
272
273int
274vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
275 size_t size, int flags)
276{
277 struct inode *inode = dentry->d_inode;
278 struct inode *delegated_inode = NULL;
279 int error;
280
281retry_deleg:
282 inode_lock(inode);
283 error = __vfs_setxattr_locked(dentry, name, value, size, flags,
284 &delegated_inode);
285 inode_unlock(inode);
286
287 if (delegated_inode) {
288 error = break_deleg_wait(&delegated_inode);
289 if (!error)
290 goto retry_deleg;
291 }
292 return error;
293}
294EXPORT_SYMBOL_GPL(vfs_setxattr);
295
296static ssize_t
297xattr_getsecurity(struct inode *inode, const char *name, void *value,
298 size_t size)
299{
300 void *buffer = NULL;
301 ssize_t len;
302
303 if (!value || !size) {
304 len = security_inode_getsecurity(inode, name, &buffer, false);
305 goto out_noalloc;
306 }
307
308 len = security_inode_getsecurity(inode, name, &buffer, true);
309 if (len < 0)
310 return len;
311 if (size < len) {
312 len = -ERANGE;
313 goto out;
314 }
315 memcpy(value, buffer, len);
316out:
317 kfree(buffer);
318out_noalloc:
319 return len;
320}
321
322/*
323 * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
324 *
325 * Allocate memory, if not already allocated, or re-allocate correct size,
326 * before retrieving the extended attribute.
327 *
328 * Returns the result of alloc, if failed, or the getxattr operation.
329 */
330ssize_t
331vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value,
332 size_t xattr_size, gfp_t flags)
333{
334 const struct xattr_handler *handler;
335 struct inode *inode = dentry->d_inode;
336 char *value = *xattr_value;
337 int error;
338
339 error = xattr_permission(inode, name, MAY_READ);
340 if (error)
341 return error;
342
343 handler = xattr_resolve_name(inode, &name);
344 if (IS_ERR(handler))
345 return PTR_ERR(handler);
346 if (!handler->get)
347 return -EOPNOTSUPP;
348 error = handler->get(handler, dentry, inode, name, NULL, 0);
349 if (error < 0)
350 return error;
351
352 if (!value || (error > xattr_size)) {
353 value = krealloc(*xattr_value, error + 1, flags);
354 if (!value)
355 return -ENOMEM;
356 memset(value, 0, error + 1);
357 }
358
359 error = handler->get(handler, dentry, inode, name, value, error);
360 *xattr_value = value;
361 return error;
362}
363
364ssize_t
365__vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
366 void *value, size_t size)
367{
368 const struct xattr_handler *handler;
369
370 handler = xattr_resolve_name(inode, &name);
371 if (IS_ERR(handler))
372 return PTR_ERR(handler);
373 if (!handler->get)
374 return -EOPNOTSUPP;
375 return handler->get(handler, dentry, inode, name, value, size);
376}
377EXPORT_SYMBOL(__vfs_getxattr);
378
379ssize_t
380vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
381{
382 struct inode *inode = dentry->d_inode;
383 int error;
384
385 error = xattr_permission(inode, name, MAY_READ);
386 if (error)
387 return error;
388
389 error = security_inode_getxattr(dentry, name);
390 if (error)
391 return error;
392
393 if (!strncmp(name, XATTR_SECURITY_PREFIX,
394 XATTR_SECURITY_PREFIX_LEN)) {
395 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
396 int ret = xattr_getsecurity(inode, suffix, value, size);
397 /*
398 * Only overwrite the return value if a security module
399 * is actually active.
400 */
401 if (ret == -EOPNOTSUPP)
402 goto nolsm;
403 return ret;
404 }
405nolsm:
406 return __vfs_getxattr(dentry, inode, name, value, size);
407}
408EXPORT_SYMBOL_GPL(vfs_getxattr);
409
410ssize_t
411vfs_listxattr(struct dentry *dentry, char *list, size_t size)
412{
413 struct inode *inode = d_inode(dentry);
414 ssize_t error;
415
416 error = security_inode_listxattr(dentry);
417 if (error)
418 return error;
419 if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) {
420 error = inode->i_op->listxattr(dentry, list, size);
421 } else {
422 error = security_inode_listsecurity(inode, list, size);
423 if (size && error > size)
424 error = -ERANGE;
425 }
426 return error;
427}
428EXPORT_SYMBOL_GPL(vfs_listxattr);
429
430int
431__vfs_removexattr(struct dentry *dentry, const char *name)
432{
433 struct inode *inode = d_inode(dentry);
434 const struct xattr_handler *handler;
435
436 handler = xattr_resolve_name(inode, &name);
437 if (IS_ERR(handler))
438 return PTR_ERR(handler);
439 if (!handler->set)
440 return -EOPNOTSUPP;
441 return handler->set(handler, dentry, inode, name, NULL, 0, XATTR_REPLACE);
442}
443EXPORT_SYMBOL(__vfs_removexattr);
444
445/**
446 * __vfs_removexattr_locked: set an extended attribute while holding the inode
447 * lock
448 *
449 * @dentry - object to perform setxattr on
450 * @name - name of xattr to remove
451 * @delegated_inode - on return, will contain an inode pointer that
452 * a delegation was broken on, NULL if none.
453 */
454int
455__vfs_removexattr_locked(struct dentry *dentry, const char *name,
456 struct inode **delegated_inode)
457{
458 struct inode *inode = dentry->d_inode;
459 int error;
460
461 error = xattr_permission(inode, name, MAY_WRITE);
462 if (error)
463 return error;
464
465 error = security_inode_removexattr(dentry, name);
466 if (error)
467 goto out;
468
469 error = try_break_deleg(inode, delegated_inode);
470 if (error)
471 goto out;
472
473 error = __vfs_removexattr(dentry, name);
474
475 if (!error) {
476 fsnotify_xattr(dentry);
477 evm_inode_post_removexattr(dentry, name);
478 }
479
480out:
481 return error;
482}
483EXPORT_SYMBOL_GPL(__vfs_removexattr_locked);
484
485int
486vfs_removexattr(struct dentry *dentry, const char *name)
487{
488 struct inode *inode = dentry->d_inode;
489 struct inode *delegated_inode = NULL;
490 int error;
491
492retry_deleg:
493 inode_lock(inode);
494 error = __vfs_removexattr_locked(dentry, name, &delegated_inode);
495 inode_unlock(inode);
496
497 if (delegated_inode) {
498 error = break_deleg_wait(&delegated_inode);
499 if (!error)
500 goto retry_deleg;
501 }
502
503 return error;
504}
505EXPORT_SYMBOL_GPL(vfs_removexattr);
506
507/*
508 * Extended attribute SET operations
509 */
510static long
511setxattr(struct dentry *d, const char __user *name, const void __user *value,
512 size_t size, int flags)
513{
514 int error;
515 void *kvalue = NULL;
516 char kname[XATTR_NAME_MAX + 1];
517
518 if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
519 return -EINVAL;
520
521 error = strncpy_from_user(kname, name, sizeof(kname));
522 if (error == 0 || error == sizeof(kname))
523 error = -ERANGE;
524 if (error < 0)
525 return error;
526
527 if (size) {
528 if (size > XATTR_SIZE_MAX)
529 return -E2BIG;
530 kvalue = kvmalloc(size, GFP_KERNEL);
531 if (!kvalue)
532 return -ENOMEM;
533 if (copy_from_user(kvalue, value, size)) {
534 error = -EFAULT;
535 goto out;
536 }
537 if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
538 (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
539 posix_acl_fix_xattr_from_user(kvalue, size);
540 else if (strcmp(kname, XATTR_NAME_CAPS) == 0) {
541 error = cap_convert_nscap(d, &kvalue, size);
542 if (error < 0)
543 goto out;
544 size = error;
545 }
546 }
547
548 error = vfs_setxattr(d, kname, kvalue, size, flags);
549out:
550 kvfree(kvalue);
551
552 return error;
553}
554
555static int path_setxattr(const char __user *pathname,
556 const char __user *name, const void __user *value,
557 size_t size, int flags, unsigned int lookup_flags)
558{
559 struct path path;
560 int error;
561retry:
562 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
563 if (error)
564 return error;
565 error = mnt_want_write(path.mnt);
566 if (!error) {
567 error = setxattr(path.dentry, name, value, size, flags);
568 mnt_drop_write(path.mnt);
569 }
570 path_put(&path);
571 if (retry_estale(error, lookup_flags)) {
572 lookup_flags |= LOOKUP_REVAL;
573 goto retry;
574 }
575 return error;
576}
577
578SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
579 const char __user *, name, const void __user *, value,
580 size_t, size, int, flags)
581{
582 return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW);
583}
584
585SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
586 const char __user *, name, const void __user *, value,
587 size_t, size, int, flags)
588{
589 return path_setxattr(pathname, name, value, size, flags, 0);
590}
591
592SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
593 const void __user *,value, size_t, size, int, flags)
594{
595 struct fd f = fdget(fd);
596 int error = -EBADF;
597
598 if (!f.file)
599 return error;
600 audit_file(f.file);
601 error = mnt_want_write_file(f.file);
602 if (!error) {
603 error = setxattr(f.file->f_path.dentry, name, value, size, flags);
604 mnt_drop_write_file(f.file);
605 }
606 fdput(f);
607 return error;
608}
609
610/*
611 * Extended attribute GET operations
612 */
613static ssize_t
614getxattr(struct dentry *d, const char __user *name, void __user *value,
615 size_t size)
616{
617 ssize_t error;
618 void *kvalue = NULL;
619 char kname[XATTR_NAME_MAX + 1];
620
621 error = strncpy_from_user(kname, name, sizeof(kname));
622 if (error == 0 || error == sizeof(kname))
623 error = -ERANGE;
624 if (error < 0)
625 return error;
626
627 if (size) {
628 if (size > XATTR_SIZE_MAX)
629 size = XATTR_SIZE_MAX;
630 kvalue = kvzalloc(size, GFP_KERNEL);
631 if (!kvalue)
632 return -ENOMEM;
633 }
634
635 error = vfs_getxattr(d, kname, kvalue, size);
636 if (error > 0) {
637 if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
638 (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
639 posix_acl_fix_xattr_to_user(kvalue, error);
640 if (size && copy_to_user(value, kvalue, error))
641 error = -EFAULT;
642 } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
643 /* The file system tried to returned a value bigger
644 than XATTR_SIZE_MAX bytes. Not possible. */
645 error = -E2BIG;
646 }
647
648 kvfree(kvalue);
649
650 return error;
651}
652
653static ssize_t path_getxattr(const char __user *pathname,
654 const char __user *name, void __user *value,
655 size_t size, unsigned int lookup_flags)
656{
657 struct path path;
658 ssize_t error;
659retry:
660 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
661 if (error)
662 return error;
663 error = getxattr(path.dentry, name, value, size);
664 path_put(&path);
665 if (retry_estale(error, lookup_flags)) {
666 lookup_flags |= LOOKUP_REVAL;
667 goto retry;
668 }
669 return error;
670}
671
672SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
673 const char __user *, name, void __user *, value, size_t, size)
674{
675 return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW);
676}
677
678SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
679 const char __user *, name, void __user *, value, size_t, size)
680{
681 return path_getxattr(pathname, name, value, size, 0);
682}
683
684SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
685 void __user *, value, size_t, size)
686{
687 struct fd f = fdget(fd);
688 ssize_t error = -EBADF;
689
690 if (!f.file)
691 return error;
692 audit_file(f.file);
693 error = getxattr(f.file->f_path.dentry, name, value, size);
694 fdput(f);
695 return error;
696}
697
698/*
699 * Extended attribute LIST operations
700 */
701static ssize_t
702listxattr(struct dentry *d, char __user *list, size_t size)
703{
704 ssize_t error;
705 char *klist = NULL;
706
707 if (size) {
708 if (size > XATTR_LIST_MAX)
709 size = XATTR_LIST_MAX;
710 klist = kvmalloc(size, GFP_KERNEL);
711 if (!klist)
712 return -ENOMEM;
713 }
714
715 error = vfs_listxattr(d, klist, size);
716 if (error > 0) {
717 if (size && copy_to_user(list, klist, error))
718 error = -EFAULT;
719 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
720 /* The file system tried to returned a list bigger
721 than XATTR_LIST_MAX bytes. Not possible. */
722 error = -E2BIG;
723 }
724
725 kvfree(klist);
726
727 return error;
728}
729
730static ssize_t path_listxattr(const char __user *pathname, char __user *list,
731 size_t size, unsigned int lookup_flags)
732{
733 struct path path;
734 ssize_t error;
735retry:
736 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
737 if (error)
738 return error;
739 error = listxattr(path.dentry, list, size);
740 path_put(&path);
741 if (retry_estale(error, lookup_flags)) {
742 lookup_flags |= LOOKUP_REVAL;
743 goto retry;
744 }
745 return error;
746}
747
748SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
749 size_t, size)
750{
751 return path_listxattr(pathname, list, size, LOOKUP_FOLLOW);
752}
753
754SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
755 size_t, size)
756{
757 return path_listxattr(pathname, list, size, 0);
758}
759
760SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
761{
762 struct fd f = fdget(fd);
763 ssize_t error = -EBADF;
764
765 if (!f.file)
766 return error;
767 audit_file(f.file);
768 error = listxattr(f.file->f_path.dentry, list, size);
769 fdput(f);
770 return error;
771}
772
773/*
774 * Extended attribute REMOVE operations
775 */
776static long
777removexattr(struct dentry *d, const char __user *name)
778{
779 int error;
780 char kname[XATTR_NAME_MAX + 1];
781
782 error = strncpy_from_user(kname, name, sizeof(kname));
783 if (error == 0 || error == sizeof(kname))
784 error = -ERANGE;
785 if (error < 0)
786 return error;
787
788 return vfs_removexattr(d, kname);
789}
790
791static int path_removexattr(const char __user *pathname,
792 const char __user *name, unsigned int lookup_flags)
793{
794 struct path path;
795 int error;
796retry:
797 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
798 if (error)
799 return error;
800 error = mnt_want_write(path.mnt);
801 if (!error) {
802 error = removexattr(path.dentry, name);
803 mnt_drop_write(path.mnt);
804 }
805 path_put(&path);
806 if (retry_estale(error, lookup_flags)) {
807 lookup_flags |= LOOKUP_REVAL;
808 goto retry;
809 }
810 return error;
811}
812
813SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
814 const char __user *, name)
815{
816 return path_removexattr(pathname, name, LOOKUP_FOLLOW);
817}
818
819SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
820 const char __user *, name)
821{
822 return path_removexattr(pathname, name, 0);
823}
824
825SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
826{
827 struct fd f = fdget(fd);
828 int error = -EBADF;
829
830 if (!f.file)
831 return error;
832 audit_file(f.file);
833 error = mnt_want_write_file(f.file);
834 if (!error) {
835 error = removexattr(f.file->f_path.dentry, name);
836 mnt_drop_write_file(f.file);
837 }
838 fdput(f);
839 return error;
840}
841
842/*
843 * Combine the results of the list() operation from every xattr_handler in the
844 * list.
845 */
846ssize_t
847generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
848{
849 const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
850 unsigned int size = 0;
851
852 if (!buffer) {
853 for_each_xattr_handler(handlers, handler) {
854 if (!handler->name ||
855 (handler->list && !handler->list(dentry)))
856 continue;
857 size += strlen(handler->name) + 1;
858 }
859 } else {
860 char *buf = buffer;
861 size_t len;
862
863 for_each_xattr_handler(handlers, handler) {
864 if (!handler->name ||
865 (handler->list && !handler->list(dentry)))
866 continue;
867 len = strlen(handler->name);
868 if (len + 1 > buffer_size)
869 return -ERANGE;
870 memcpy(buf, handler->name, len + 1);
871 buf += len + 1;
872 buffer_size -= len + 1;
873 }
874 size = buf - buffer;
875 }
876 return size;
877}
878EXPORT_SYMBOL(generic_listxattr);
879
880/**
881 * xattr_full_name - Compute full attribute name from suffix
882 *
883 * @handler: handler of the xattr_handler operation
884 * @name: name passed to the xattr_handler operation
885 *
886 * The get and set xattr handler operations are called with the remainder of
887 * the attribute name after skipping the handler's prefix: for example, "foo"
888 * is passed to the get operation of a handler with prefix "user." to get
889 * attribute "user.foo". The full name is still "there" in the name though.
890 *
891 * Note: the list xattr handler operation when called from the vfs is passed a
892 * NULL name; some file systems use this operation internally, with varying
893 * semantics.
894 */
895const char *xattr_full_name(const struct xattr_handler *handler,
896 const char *name)
897{
898 size_t prefix_len = strlen(xattr_prefix(handler));
899
900 return name - prefix_len;
901}
902EXPORT_SYMBOL(xattr_full_name);
903
904/*
905 * Allocate new xattr and copy in the value; but leave the name to callers.
906 */
907struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
908{
909 struct simple_xattr *new_xattr;
910 size_t len;
911
912 /* wrap around? */
913 len = sizeof(*new_xattr) + size;
914 if (len < sizeof(*new_xattr))
915 return NULL;
916
917 new_xattr = kvmalloc(len, GFP_KERNEL);
918 if (!new_xattr)
919 return NULL;
920
921 new_xattr->size = size;
922 memcpy(new_xattr->value, value, size);
923 return new_xattr;
924}
925
926/*
927 * xattr GET operation for in-memory/pseudo filesystems
928 */
929int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
930 void *buffer, size_t size)
931{
932 struct simple_xattr *xattr;
933 int ret = -ENODATA;
934
935 spin_lock(&xattrs->lock);
936 list_for_each_entry(xattr, &xattrs->head, list) {
937 if (strcmp(name, xattr->name))
938 continue;
939
940 ret = xattr->size;
941 if (buffer) {
942 if (size < xattr->size)
943 ret = -ERANGE;
944 else
945 memcpy(buffer, xattr->value, xattr->size);
946 }
947 break;
948 }
949 spin_unlock(&xattrs->lock);
950 return ret;
951}
952
953/**
954 * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
955 * @xattrs: target simple_xattr list
956 * @name: name of the extended attribute
957 * @value: value of the xattr. If %NULL, will remove the attribute.
958 * @size: size of the new xattr
959 * @flags: %XATTR_{CREATE|REPLACE}
960 * @removed_size: returns size of the removed xattr, -1 if none removed
961 *
962 * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
963 * with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist;
964 * otherwise, fails with -ENODATA.
965 *
966 * Returns 0 on success, -errno on failure.
967 */
968int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
969 const void *value, size_t size, int flags,
970 ssize_t *removed_size)
971{
972 struct simple_xattr *xattr;
973 struct simple_xattr *new_xattr = NULL;
974 int err = 0;
975
976 if (removed_size)
977 *removed_size = -1;
978
979 /* value == NULL means remove */
980 if (value) {
981 new_xattr = simple_xattr_alloc(value, size);
982 if (!new_xattr)
983 return -ENOMEM;
984
985 new_xattr->name = kstrdup(name, GFP_KERNEL);
986 if (!new_xattr->name) {
987 kvfree(new_xattr);
988 return -ENOMEM;
989 }
990 }
991
992 spin_lock(&xattrs->lock);
993 list_for_each_entry(xattr, &xattrs->head, list) {
994 if (!strcmp(name, xattr->name)) {
995 if (flags & XATTR_CREATE) {
996 xattr = new_xattr;
997 err = -EEXIST;
998 } else if (new_xattr) {
999 list_replace(&xattr->list, &new_xattr->list);
1000 if (removed_size)
1001 *removed_size = xattr->size;
1002 } else {
1003 list_del(&xattr->list);
1004 if (removed_size)
1005 *removed_size = xattr->size;
1006 }
1007 goto out;
1008 }
1009 }
1010 if (flags & XATTR_REPLACE) {
1011 xattr = new_xattr;
1012 err = -ENODATA;
1013 } else {
1014 list_add(&new_xattr->list, &xattrs->head);
1015 xattr = NULL;
1016 }
1017out:
1018 spin_unlock(&xattrs->lock);
1019 if (xattr) {
1020 kfree(xattr->name);
1021 kvfree(xattr);
1022 }
1023 return err;
1024
1025}
1026
1027static bool xattr_is_trusted(const char *name)
1028{
1029 return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
1030}
1031
1032static int xattr_list_one(char **buffer, ssize_t *remaining_size,
1033 const char *name)
1034{
1035 size_t len = strlen(name) + 1;
1036 if (*buffer) {
1037 if (*remaining_size < len)
1038 return -ERANGE;
1039 memcpy(*buffer, name, len);
1040 *buffer += len;
1041 }
1042 *remaining_size -= len;
1043 return 0;
1044}
1045
1046/*
1047 * xattr LIST operation for in-memory/pseudo filesystems
1048 */
1049ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
1050 char *buffer, size_t size)
1051{
1052 bool trusted = capable(CAP_SYS_ADMIN);
1053 struct simple_xattr *xattr;
1054 ssize_t remaining_size = size;
1055 int err = 0;
1056
1057#ifdef CONFIG_FS_POSIX_ACL
1058 if (IS_POSIXACL(inode)) {
1059 if (inode->i_acl) {
1060 err = xattr_list_one(&buffer, &remaining_size,
1061 XATTR_NAME_POSIX_ACL_ACCESS);
1062 if (err)
1063 return err;
1064 }
1065 if (inode->i_default_acl) {
1066 err = xattr_list_one(&buffer, &remaining_size,
1067 XATTR_NAME_POSIX_ACL_DEFAULT);
1068 if (err)
1069 return err;
1070 }
1071 }
1072#endif
1073
1074 spin_lock(&xattrs->lock);
1075 list_for_each_entry(xattr, &xattrs->head, list) {
1076 /* skip "trusted." attributes for unprivileged callers */
1077 if (!trusted && xattr_is_trusted(xattr->name))
1078 continue;
1079
1080 err = xattr_list_one(&buffer, &remaining_size, xattr->name);
1081 if (err)
1082 break;
1083 }
1084 spin_unlock(&xattrs->lock);
1085
1086 return err ? err : size - remaining_size;
1087}
1088
1089/*
1090 * Adds an extended attribute to the list
1091 */
1092void simple_xattr_list_add(struct simple_xattrs *xattrs,
1093 struct simple_xattr *new_xattr)
1094{
1095 spin_lock(&xattrs->lock);
1096 list_add(&new_xattr->list, &xattrs->head);
1097 spin_unlock(&xattrs->lock);
1098}