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