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