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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#include <linux/posix_acl_xattr.h>
24
25#include <asm/uaccess.h>
26
27/*
28 * Check permissions for extended attribute access. This is a bit complicated
29 * because different namespaces have very different rules.
30 */
31static int
32xattr_permission(struct inode *inode, const char *name, int mask)
33{
34 /*
35 * We can never set or remove an extended attribute on a read-only
36 * filesystem or on an immutable / append-only inode.
37 */
38 if (mask & MAY_WRITE) {
39 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
40 return -EPERM;
41 }
42
43 /*
44 * No restriction for security.* and system.* from the VFS. Decision
45 * on these is left to the underlying filesystem / security module.
46 */
47 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
48 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
49 return 0;
50
51 /*
52 * The trusted.* namespace can only be accessed by privileged users.
53 */
54 if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
55 if (!capable(CAP_SYS_ADMIN))
56 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
57 return 0;
58 }
59
60 /*
61 * In the user.* namespace, only regular files and directories can have
62 * extended attributes. For sticky directories, only the owner and
63 * privileged users can write attributes.
64 */
65 if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
66 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
67 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
68 if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
69 (mask & MAY_WRITE) && !inode_owner_or_capable(inode))
70 return -EPERM;
71 }
72
73 return inode_permission(inode, mask);
74}
75
76/**
77 * __vfs_setxattr_noperm - perform setxattr operation without performing
78 * permission checks.
79 *
80 * @dentry - object to perform setxattr on
81 * @name - xattr name to set
82 * @value - value to set @name to
83 * @size - size of @value
84 * @flags - flags to pass into filesystem operations
85 *
86 * returns the result of the internal setxattr or setsecurity operations.
87 *
88 * This function requires the caller to lock the inode's i_mutex before it
89 * is executed. It also assumes that the caller will make the appropriate
90 * permission checks.
91 */
92int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
93 const void *value, size_t size, int flags)
94{
95 struct inode *inode = dentry->d_inode;
96 int error = -EOPNOTSUPP;
97 int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
98 XATTR_SECURITY_PREFIX_LEN);
99
100 if (issec)
101 inode->i_flags &= ~S_NOSEC;
102 if (inode->i_op->setxattr) {
103 error = inode->i_op->setxattr(dentry, name, value, size, flags);
104 if (!error) {
105 fsnotify_xattr(dentry);
106 security_inode_post_setxattr(dentry, name, value,
107 size, flags);
108 }
109 } else if (issec) {
110 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
111 error = security_inode_setsecurity(inode, suffix, value,
112 size, flags);
113 if (!error)
114 fsnotify_xattr(dentry);
115 }
116
117 return error;
118}
119
120
121int
122vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
123 size_t size, int flags)
124{
125 struct inode *inode = dentry->d_inode;
126 int error;
127
128 error = xattr_permission(inode, name, MAY_WRITE);
129 if (error)
130 return error;
131
132 mutex_lock(&inode->i_mutex);
133 error = security_inode_setxattr(dentry, name, value, size, flags);
134 if (error)
135 goto out;
136
137 error = __vfs_setxattr_noperm(dentry, name, value, size, flags);
138
139out:
140 mutex_unlock(&inode->i_mutex);
141 return error;
142}
143EXPORT_SYMBOL_GPL(vfs_setxattr);
144
145ssize_t
146xattr_getsecurity(struct inode *inode, const char *name, void *value,
147 size_t size)
148{
149 void *buffer = NULL;
150 ssize_t len;
151
152 if (!value || !size) {
153 len = security_inode_getsecurity(inode, name, &buffer, false);
154 goto out_noalloc;
155 }
156
157 len = security_inode_getsecurity(inode, name, &buffer, true);
158 if (len < 0)
159 return len;
160 if (size < len) {
161 len = -ERANGE;
162 goto out;
163 }
164 memcpy(value, buffer, len);
165out:
166 security_release_secctx(buffer, len);
167out_noalloc:
168 return len;
169}
170EXPORT_SYMBOL_GPL(xattr_getsecurity);
171
172/*
173 * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
174 *
175 * Allocate memory, if not already allocated, or re-allocate correct size,
176 * before retrieving the extended attribute.
177 *
178 * Returns the result of alloc, if failed, or the getxattr operation.
179 */
180ssize_t
181vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value,
182 size_t xattr_size, gfp_t flags)
183{
184 struct inode *inode = dentry->d_inode;
185 char *value = *xattr_value;
186 int error;
187
188 error = xattr_permission(inode, name, MAY_READ);
189 if (error)
190 return error;
191
192 if (!inode->i_op->getxattr)
193 return -EOPNOTSUPP;
194
195 error = inode->i_op->getxattr(dentry, name, NULL, 0);
196 if (error < 0)
197 return error;
198
199 if (!value || (error > xattr_size)) {
200 value = krealloc(*xattr_value, error + 1, flags);
201 if (!value)
202 return -ENOMEM;
203 memset(value, 0, error + 1);
204 }
205
206 error = inode->i_op->getxattr(dentry, name, value, error);
207 *xattr_value = value;
208 return error;
209}
210
211/* Compare an extended attribute value with the given value */
212int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name,
213 const char *value, size_t size, gfp_t flags)
214{
215 char *xattr_value = NULL;
216 int rc;
217
218 rc = vfs_getxattr_alloc(dentry, xattr_name, &xattr_value, 0, flags);
219 if (rc < 0)
220 return rc;
221
222 if ((rc != size) || (memcmp(xattr_value, value, rc) != 0))
223 rc = -EINVAL;
224 else
225 rc = 0;
226 kfree(xattr_value);
227 return rc;
228}
229
230ssize_t
231vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
232{
233 struct inode *inode = dentry->d_inode;
234 int error;
235
236 error = xattr_permission(inode, name, MAY_READ);
237 if (error)
238 return error;
239
240 error = security_inode_getxattr(dentry, name);
241 if (error)
242 return error;
243
244 if (!strncmp(name, XATTR_SECURITY_PREFIX,
245 XATTR_SECURITY_PREFIX_LEN)) {
246 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
247 int ret = xattr_getsecurity(inode, suffix, value, size);
248 /*
249 * Only overwrite the return value if a security module
250 * is actually active.
251 */
252 if (ret == -EOPNOTSUPP)
253 goto nolsm;
254 return ret;
255 }
256nolsm:
257 if (inode->i_op->getxattr)
258 error = inode->i_op->getxattr(dentry, name, value, size);
259 else
260 error = -EOPNOTSUPP;
261
262 return error;
263}
264EXPORT_SYMBOL_GPL(vfs_getxattr);
265
266ssize_t
267vfs_listxattr(struct dentry *d, char *list, size_t size)
268{
269 ssize_t error;
270
271 error = security_inode_listxattr(d);
272 if (error)
273 return error;
274 error = -EOPNOTSUPP;
275 if (d->d_inode->i_op->listxattr) {
276 error = d->d_inode->i_op->listxattr(d, list, size);
277 } else {
278 error = security_inode_listsecurity(d->d_inode, list, size);
279 if (size && error > size)
280 error = -ERANGE;
281 }
282 return error;
283}
284EXPORT_SYMBOL_GPL(vfs_listxattr);
285
286int
287vfs_removexattr(struct dentry *dentry, const char *name)
288{
289 struct inode *inode = dentry->d_inode;
290 int error;
291
292 if (!inode->i_op->removexattr)
293 return -EOPNOTSUPP;
294
295 error = xattr_permission(inode, name, MAY_WRITE);
296 if (error)
297 return error;
298
299 mutex_lock(&inode->i_mutex);
300 error = security_inode_removexattr(dentry, name);
301 if (error) {
302 mutex_unlock(&inode->i_mutex);
303 return error;
304 }
305
306 error = inode->i_op->removexattr(dentry, name);
307 mutex_unlock(&inode->i_mutex);
308
309 if (!error) {
310 fsnotify_xattr(dentry);
311 evm_inode_post_removexattr(dentry, name);
312 }
313 return error;
314}
315EXPORT_SYMBOL_GPL(vfs_removexattr);
316
317
318/*
319 * Extended attribute SET operations
320 */
321static long
322setxattr(struct dentry *d, const char __user *name, const void __user *value,
323 size_t size, int flags)
324{
325 int error;
326 void *kvalue = NULL;
327 void *vvalue = NULL; /* If non-NULL, we used vmalloc() */
328 char kname[XATTR_NAME_MAX + 1];
329
330 if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
331 return -EINVAL;
332
333 error = strncpy_from_user(kname, name, sizeof(kname));
334 if (error == 0 || error == sizeof(kname))
335 error = -ERANGE;
336 if (error < 0)
337 return error;
338
339 if (size) {
340 if (size > XATTR_SIZE_MAX)
341 return -E2BIG;
342 kvalue = kmalloc(size, GFP_KERNEL | __GFP_NOWARN);
343 if (!kvalue) {
344 vvalue = vmalloc(size);
345 if (!vvalue)
346 return -ENOMEM;
347 kvalue = vvalue;
348 }
349 if (copy_from_user(kvalue, value, size)) {
350 error = -EFAULT;
351 goto out;
352 }
353 if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
354 (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
355 posix_acl_fix_xattr_from_user(kvalue, size);
356 }
357
358 error = vfs_setxattr(d, kname, kvalue, size, flags);
359out:
360 if (vvalue)
361 vfree(vvalue);
362 else
363 kfree(kvalue);
364 return error;
365}
366
367SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
368 const char __user *, name, const void __user *, value,
369 size_t, size, int, flags)
370{
371 struct path path;
372 int error;
373 unsigned int lookup_flags = LOOKUP_FOLLOW;
374retry:
375 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
376 if (error)
377 return error;
378 error = mnt_want_write(path.mnt);
379 if (!error) {
380 error = setxattr(path.dentry, name, value, size, flags);
381 mnt_drop_write(path.mnt);
382 }
383 path_put(&path);
384 if (retry_estale(error, lookup_flags)) {
385 lookup_flags |= LOOKUP_REVAL;
386 goto retry;
387 }
388 return error;
389}
390
391SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
392 const char __user *, name, const void __user *, value,
393 size_t, size, int, flags)
394{
395 struct path path;
396 int error;
397 unsigned int lookup_flags = 0;
398retry:
399 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
400 if (error)
401 return error;
402 error = mnt_want_write(path.mnt);
403 if (!error) {
404 error = setxattr(path.dentry, name, value, size, flags);
405 mnt_drop_write(path.mnt);
406 }
407 path_put(&path);
408 if (retry_estale(error, lookup_flags)) {
409 lookup_flags |= LOOKUP_REVAL;
410 goto retry;
411 }
412 return error;
413}
414
415SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
416 const void __user *,value, size_t, size, int, flags)
417{
418 struct fd f = fdget(fd);
419 struct dentry *dentry;
420 int error = -EBADF;
421
422 if (!f.file)
423 return error;
424 dentry = f.file->f_path.dentry;
425 audit_inode(NULL, dentry, 0);
426 error = mnt_want_write_file(f.file);
427 if (!error) {
428 error = setxattr(dentry, name, value, size, flags);
429 mnt_drop_write_file(f.file);
430 }
431 fdput(f);
432 return error;
433}
434
435/*
436 * Extended attribute GET operations
437 */
438static ssize_t
439getxattr(struct dentry *d, const char __user *name, void __user *value,
440 size_t size)
441{
442 ssize_t error;
443 void *kvalue = NULL;
444 void *vvalue = NULL;
445 char kname[XATTR_NAME_MAX + 1];
446
447 error = strncpy_from_user(kname, name, sizeof(kname));
448 if (error == 0 || error == sizeof(kname))
449 error = -ERANGE;
450 if (error < 0)
451 return error;
452
453 if (size) {
454 if (size > XATTR_SIZE_MAX)
455 size = XATTR_SIZE_MAX;
456 kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
457 if (!kvalue) {
458 vvalue = vmalloc(size);
459 if (!vvalue)
460 return -ENOMEM;
461 kvalue = vvalue;
462 }
463 }
464
465 error = vfs_getxattr(d, kname, kvalue, size);
466 if (error > 0) {
467 if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
468 (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
469 posix_acl_fix_xattr_to_user(kvalue, size);
470 if (size && copy_to_user(value, kvalue, error))
471 error = -EFAULT;
472 } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
473 /* The file system tried to returned a value bigger
474 than XATTR_SIZE_MAX bytes. Not possible. */
475 error = -E2BIG;
476 }
477 if (vvalue)
478 vfree(vvalue);
479 else
480 kfree(kvalue);
481 return error;
482}
483
484SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
485 const char __user *, name, void __user *, value, size_t, size)
486{
487 struct path path;
488 ssize_t error;
489 unsigned int lookup_flags = LOOKUP_FOLLOW;
490retry:
491 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
492 if (error)
493 return error;
494 error = getxattr(path.dentry, name, value, size);
495 path_put(&path);
496 if (retry_estale(error, lookup_flags)) {
497 lookup_flags |= LOOKUP_REVAL;
498 goto retry;
499 }
500 return error;
501}
502
503SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
504 const char __user *, name, void __user *, value, size_t, size)
505{
506 struct path path;
507 ssize_t error;
508 unsigned int lookup_flags = 0;
509retry:
510 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
511 if (error)
512 return error;
513 error = getxattr(path.dentry, name, value, size);
514 path_put(&path);
515 if (retry_estale(error, lookup_flags)) {
516 lookup_flags |= LOOKUP_REVAL;
517 goto retry;
518 }
519 return error;
520}
521
522SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
523 void __user *, value, size_t, size)
524{
525 struct fd f = fdget(fd);
526 ssize_t error = -EBADF;
527
528 if (!f.file)
529 return error;
530 audit_inode(NULL, f.file->f_path.dentry, 0);
531 error = getxattr(f.file->f_path.dentry, name, value, size);
532 fdput(f);
533 return error;
534}
535
536/*
537 * Extended attribute LIST operations
538 */
539static ssize_t
540listxattr(struct dentry *d, char __user *list, size_t size)
541{
542 ssize_t error;
543 char *klist = NULL;
544 char *vlist = NULL; /* If non-NULL, we used vmalloc() */
545
546 if (size) {
547 if (size > XATTR_LIST_MAX)
548 size = XATTR_LIST_MAX;
549 klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL);
550 if (!klist) {
551 vlist = vmalloc(size);
552 if (!vlist)
553 return -ENOMEM;
554 klist = vlist;
555 }
556 }
557
558 error = vfs_listxattr(d, klist, size);
559 if (error > 0) {
560 if (size && copy_to_user(list, klist, error))
561 error = -EFAULT;
562 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
563 /* The file system tried to returned a list bigger
564 than XATTR_LIST_MAX bytes. Not possible. */
565 error = -E2BIG;
566 }
567 if (vlist)
568 vfree(vlist);
569 else
570 kfree(klist);
571 return error;
572}
573
574SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
575 size_t, size)
576{
577 struct path path;
578 ssize_t error;
579 unsigned int lookup_flags = LOOKUP_FOLLOW;
580retry:
581 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
582 if (error)
583 return error;
584 error = listxattr(path.dentry, list, size);
585 path_put(&path);
586 if (retry_estale(error, lookup_flags)) {
587 lookup_flags |= LOOKUP_REVAL;
588 goto retry;
589 }
590 return error;
591}
592
593SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
594 size_t, size)
595{
596 struct path path;
597 ssize_t error;
598 unsigned int lookup_flags = 0;
599retry:
600 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
601 if (error)
602 return error;
603 error = listxattr(path.dentry, list, size);
604 path_put(&path);
605 if (retry_estale(error, lookup_flags)) {
606 lookup_flags |= LOOKUP_REVAL;
607 goto retry;
608 }
609 return error;
610}
611
612SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
613{
614 struct fd f = fdget(fd);
615 ssize_t error = -EBADF;
616
617 if (!f.file)
618 return error;
619 audit_inode(NULL, f.file->f_path.dentry, 0);
620 error = listxattr(f.file->f_path.dentry, list, size);
621 fdput(f);
622 return error;
623}
624
625/*
626 * Extended attribute REMOVE operations
627 */
628static long
629removexattr(struct dentry *d, const char __user *name)
630{
631 int error;
632 char kname[XATTR_NAME_MAX + 1];
633
634 error = strncpy_from_user(kname, name, sizeof(kname));
635 if (error == 0 || error == sizeof(kname))
636 error = -ERANGE;
637 if (error < 0)
638 return error;
639
640 return vfs_removexattr(d, kname);
641}
642
643SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
644 const char __user *, name)
645{
646 struct path path;
647 int error;
648 unsigned int lookup_flags = LOOKUP_FOLLOW;
649retry:
650 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
651 if (error)
652 return error;
653 error = mnt_want_write(path.mnt);
654 if (!error) {
655 error = removexattr(path.dentry, name);
656 mnt_drop_write(path.mnt);
657 }
658 path_put(&path);
659 if (retry_estale(error, lookup_flags)) {
660 lookup_flags |= LOOKUP_REVAL;
661 goto retry;
662 }
663 return error;
664}
665
666SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
667 const char __user *, name)
668{
669 struct path path;
670 int error;
671 unsigned int lookup_flags = 0;
672retry:
673 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
674 if (error)
675 return error;
676 error = mnt_want_write(path.mnt);
677 if (!error) {
678 error = removexattr(path.dentry, name);
679 mnt_drop_write(path.mnt);
680 }
681 path_put(&path);
682 if (retry_estale(error, lookup_flags)) {
683 lookup_flags |= LOOKUP_REVAL;
684 goto retry;
685 }
686 return error;
687}
688
689SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
690{
691 struct fd f = fdget(fd);
692 struct dentry *dentry;
693 int error = -EBADF;
694
695 if (!f.file)
696 return error;
697 dentry = f.file->f_path.dentry;
698 audit_inode(NULL, dentry, 0);
699 error = mnt_want_write_file(f.file);
700 if (!error) {
701 error = removexattr(dentry, name);
702 mnt_drop_write_file(f.file);
703 }
704 fdput(f);
705 return error;
706}
707
708
709static const char *
710strcmp_prefix(const char *a, const char *a_prefix)
711{
712 while (*a_prefix && *a == *a_prefix) {
713 a++;
714 a_prefix++;
715 }
716 return *a_prefix ? NULL : a;
717}
718
719/*
720 * In order to implement different sets of xattr operations for each xattr
721 * prefix with the generic xattr API, a filesystem should create a
722 * null-terminated array of struct xattr_handler (one for each prefix) and
723 * hang a pointer to it off of the s_xattr field of the superblock.
724 *
725 * The generic_fooxattr() functions will use this list to dispatch xattr
726 * operations to the correct xattr_handler.
727 */
728#define for_each_xattr_handler(handlers, handler) \
729 for ((handler) = *(handlers)++; \
730 (handler) != NULL; \
731 (handler) = *(handlers)++)
732
733/*
734 * Find the xattr_handler with the matching prefix.
735 */
736static const struct xattr_handler *
737xattr_resolve_name(const struct xattr_handler **handlers, const char **name)
738{
739 const struct xattr_handler *handler;
740
741 if (!*name)
742 return NULL;
743
744 for_each_xattr_handler(handlers, handler) {
745 const char *n = strcmp_prefix(*name, handler->prefix);
746 if (n) {
747 *name = n;
748 break;
749 }
750 }
751 return handler;
752}
753
754/*
755 * Find the handler for the prefix and dispatch its get() operation.
756 */
757ssize_t
758generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
759{
760 const struct xattr_handler *handler;
761
762 handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
763 if (!handler)
764 return -EOPNOTSUPP;
765 return handler->get(dentry, name, buffer, size, handler->flags);
766}
767
768/*
769 * Combine the results of the list() operation from every xattr_handler in the
770 * list.
771 */
772ssize_t
773generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
774{
775 const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
776 unsigned int size = 0;
777
778 if (!buffer) {
779 for_each_xattr_handler(handlers, handler) {
780 size += handler->list(dentry, NULL, 0, NULL, 0,
781 handler->flags);
782 }
783 } else {
784 char *buf = buffer;
785
786 for_each_xattr_handler(handlers, handler) {
787 size = handler->list(dentry, buf, buffer_size,
788 NULL, 0, handler->flags);
789 if (size > buffer_size)
790 return -ERANGE;
791 buf += size;
792 buffer_size -= size;
793 }
794 size = buf - buffer;
795 }
796 return size;
797}
798
799/*
800 * Find the handler for the prefix and dispatch its set() operation.
801 */
802int
803generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
804{
805 const struct xattr_handler *handler;
806
807 if (size == 0)
808 value = ""; /* empty EA, do not remove */
809 handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
810 if (!handler)
811 return -EOPNOTSUPP;
812 return handler->set(dentry, name, value, size, flags, handler->flags);
813}
814
815/*
816 * Find the handler for the prefix and dispatch its set() operation to remove
817 * any associated extended attribute.
818 */
819int
820generic_removexattr(struct dentry *dentry, const char *name)
821{
822 const struct xattr_handler *handler;
823
824 handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
825 if (!handler)
826 return -EOPNOTSUPP;
827 return handler->set(dentry, name, NULL, 0,
828 XATTR_REPLACE, handler->flags);
829}
830
831EXPORT_SYMBOL(generic_getxattr);
832EXPORT_SYMBOL(generic_listxattr);
833EXPORT_SYMBOL(generic_setxattr);
834EXPORT_SYMBOL(generic_removexattr);
835
836/*
837 * Allocate new xattr and copy in the value; but leave the name to callers.
838 */
839struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
840{
841 struct simple_xattr *new_xattr;
842 size_t len;
843
844 /* wrap around? */
845 len = sizeof(*new_xattr) + size;
846 if (len <= sizeof(*new_xattr))
847 return NULL;
848
849 new_xattr = kmalloc(len, GFP_KERNEL);
850 if (!new_xattr)
851 return NULL;
852
853 new_xattr->size = size;
854 memcpy(new_xattr->value, value, size);
855 return new_xattr;
856}
857
858/*
859 * xattr GET operation for in-memory/pseudo filesystems
860 */
861int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
862 void *buffer, size_t size)
863{
864 struct simple_xattr *xattr;
865 int ret = -ENODATA;
866
867 spin_lock(&xattrs->lock);
868 list_for_each_entry(xattr, &xattrs->head, list) {
869 if (strcmp(name, xattr->name))
870 continue;
871
872 ret = xattr->size;
873 if (buffer) {
874 if (size < xattr->size)
875 ret = -ERANGE;
876 else
877 memcpy(buffer, xattr->value, xattr->size);
878 }
879 break;
880 }
881 spin_unlock(&xattrs->lock);
882 return ret;
883}
884
885static int __simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
886 const void *value, size_t size, int flags)
887{
888 struct simple_xattr *xattr;
889 struct simple_xattr *new_xattr = NULL;
890 int err = 0;
891
892 /* value == NULL means remove */
893 if (value) {
894 new_xattr = simple_xattr_alloc(value, size);
895 if (!new_xattr)
896 return -ENOMEM;
897
898 new_xattr->name = kstrdup(name, GFP_KERNEL);
899 if (!new_xattr->name) {
900 kfree(new_xattr);
901 return -ENOMEM;
902 }
903 }
904
905 spin_lock(&xattrs->lock);
906 list_for_each_entry(xattr, &xattrs->head, list) {
907 if (!strcmp(name, xattr->name)) {
908 if (flags & XATTR_CREATE) {
909 xattr = new_xattr;
910 err = -EEXIST;
911 } else if (new_xattr) {
912 list_replace(&xattr->list, &new_xattr->list);
913 } else {
914 list_del(&xattr->list);
915 }
916 goto out;
917 }
918 }
919 if (flags & XATTR_REPLACE) {
920 xattr = new_xattr;
921 err = -ENODATA;
922 } else {
923 list_add(&new_xattr->list, &xattrs->head);
924 xattr = NULL;
925 }
926out:
927 spin_unlock(&xattrs->lock);
928 if (xattr) {
929 kfree(xattr->name);
930 kfree(xattr);
931 }
932 return err;
933
934}
935
936/**
937 * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
938 * @xattrs: target simple_xattr list
939 * @name: name of the new extended attribute
940 * @value: value of the new xattr. If %NULL, will remove the attribute
941 * @size: size of the new xattr
942 * @flags: %XATTR_{CREATE|REPLACE}
943 *
944 * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
945 * with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist;
946 * otherwise, fails with -ENODATA.
947 *
948 * Returns 0 on success, -errno on failure.
949 */
950int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
951 const void *value, size_t size, int flags)
952{
953 if (size == 0)
954 value = ""; /* empty EA, do not remove */
955 return __simple_xattr_set(xattrs, name, value, size, flags);
956}
957
958/*
959 * xattr REMOVE operation for in-memory/pseudo filesystems
960 */
961int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name)
962{
963 return __simple_xattr_set(xattrs, name, NULL, 0, XATTR_REPLACE);
964}
965
966static bool xattr_is_trusted(const char *name)
967{
968 return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
969}
970
971/*
972 * xattr LIST operation for in-memory/pseudo filesystems
973 */
974ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer,
975 size_t size)
976{
977 bool trusted = capable(CAP_SYS_ADMIN);
978 struct simple_xattr *xattr;
979 size_t used = 0;
980
981 spin_lock(&xattrs->lock);
982 list_for_each_entry(xattr, &xattrs->head, list) {
983 size_t len;
984
985 /* skip "trusted." attributes for unprivileged callers */
986 if (!trusted && xattr_is_trusted(xattr->name))
987 continue;
988
989 len = strlen(xattr->name) + 1;
990 used += len;
991 if (buffer) {
992 if (size < used) {
993 used = -ERANGE;
994 break;
995 }
996 memcpy(buffer, xattr->name, len);
997 buffer += len;
998 }
999 }
1000 spin_unlock(&xattrs->lock);
1001
1002 return used;
1003}
1004
1005/*
1006 * Adds an extended attribute to the list
1007 */
1008void simple_xattr_list_add(struct simple_xattrs *xattrs,
1009 struct simple_xattr *new_xattr)
1010{
1011 spin_lock(&xattrs->lock);
1012 list_add(&new_xattr->list, &xattrs->head);
1013 spin_unlock(&xattrs->lock);
1014}
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}