blob: 4523aca79659c24f5d2ca3b8ee415ddd9588b73f [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/file.h>
13#include <linux/xattr.h>
14#include <linux/namei.h>
15#include <linux/security.h>
16#include <linux/syscalls.h>
17#include <linux/module.h>
Robert Love0eeca282005-07-12 17:06:03 -040018#include <linux/fsnotify.h>
Amy Griffis73241cc2005-11-03 16:00:25 +000019#include <linux/audit.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <asm/uaccess.h>
21
Christoph Hellwig5be196e2006-01-09 20:51:55 -080022
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080023/*
24 * Check permissions for extended attribute access. This is a bit complicated
25 * because different namespaces have very different rules.
26 */
27static int
28xattr_permission(struct inode *inode, const char *name, int mask)
29{
30 /*
31 * We can never set or remove an extended attribute on a read-only
32 * filesystem or on an immutable / append-only inode.
33 */
34 if (mask & MAY_WRITE) {
35 if (IS_RDONLY(inode))
36 return -EROFS;
37 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
38 return -EPERM;
39 }
40
41 /*
42 * No restriction for security.* and system.* from the VFS. Decision
43 * on these is left to the underlying filesystem / security module.
44 */
45 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
46 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
47 return 0;
48
49 /*
Andreas Gruenbacherf1f2d872006-11-02 22:07:29 -080050 * The trusted.* namespace can only be accessed by a privileged user.
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080051 */
52 if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
53 return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);
54
Andreas Gruenbacherf1f2d872006-11-02 22:07:29 -080055 /* In user.* namespace, only regular files and directories can have
56 * extended attributes. For sticky directories, only the owner and
57 * privileged user can write attributes.
58 */
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080059 if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
Andreas Gruenbacherf1f2d872006-11-02 22:07:29 -080060 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
61 return -EPERM;
62 if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
63 (mask & MAY_WRITE) && (current->fsuid != inode->i_uid) &&
64 !capable(CAP_FOWNER))
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080065 return -EPERM;
66 }
67
68 return permission(inode, mask, NULL);
69}
70
Christoph Hellwig5be196e2006-01-09 20:51:55 -080071int
72vfs_setxattr(struct dentry *dentry, char *name, void *value,
73 size_t size, int flags)
74{
75 struct inode *inode = dentry->d_inode;
76 int error;
77
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080078 error = xattr_permission(inode, name, MAY_WRITE);
79 if (error)
80 return error;
81
Christoph Hellwig5be196e2006-01-09 20:51:55 -080082 mutex_lock(&inode->i_mutex);
83 error = security_inode_setxattr(dentry, name, value, size, flags);
84 if (error)
85 goto out;
86 error = -EOPNOTSUPP;
87 if (inode->i_op->setxattr) {
88 error = inode->i_op->setxattr(dentry, name, value, size, flags);
89 if (!error) {
90 fsnotify_xattr(dentry);
91 security_inode_post_setxattr(dentry, name, value,
92 size, flags);
93 }
94 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080095 XATTR_SECURITY_PREFIX_LEN)) {
96 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
Christoph Hellwig5be196e2006-01-09 20:51:55 -080097 error = security_inode_setsecurity(inode, suffix, value,
98 size, flags);
99 if (!error)
100 fsnotify_xattr(dentry);
101 }
102out:
103 mutex_unlock(&inode->i_mutex);
104 return error;
105}
106EXPORT_SYMBOL_GPL(vfs_setxattr);
107
108ssize_t
109vfs_getxattr(struct dentry *dentry, char *name, void *value, size_t size)
110{
111 struct inode *inode = dentry->d_inode;
112 int error;
113
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800114 error = xattr_permission(inode, name, MAY_READ);
115 if (error)
116 return error;
117
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800118 error = security_inode_getxattr(dentry, name);
119 if (error)
120 return error;
121
122 if (inode->i_op->getxattr)
123 error = inode->i_op->getxattr(dentry, name, value, size);
124 else
125 error = -EOPNOTSUPP;
126
127 if (!strncmp(name, XATTR_SECURITY_PREFIX,
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800128 XATTR_SECURITY_PREFIX_LEN)) {
129 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800130 int ret = security_inode_getsecurity(inode, suffix, value,
131 size, error);
132 /*
133 * Only overwrite the return value if a security module
134 * is actually active.
135 */
136 if (ret != -EOPNOTSUPP)
137 error = ret;
138 }
139
140 return error;
141}
142EXPORT_SYMBOL_GPL(vfs_getxattr);
143
Bill Nottingham659564c2006-10-09 16:10:48 -0400144ssize_t
145vfs_listxattr(struct dentry *d, char *list, size_t size)
146{
147 ssize_t error;
148
149 error = security_inode_listxattr(d);
150 if (error)
151 return error;
152 error = -EOPNOTSUPP;
153 if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
154 error = d->d_inode->i_op->listxattr(d, list, size);
155 } else {
156 error = security_inode_listsecurity(d->d_inode, list, size);
157 if (size && error > size)
158 error = -ERANGE;
159 }
160 return error;
161}
162EXPORT_SYMBOL_GPL(vfs_listxattr);
163
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800164int
165vfs_removexattr(struct dentry *dentry, char *name)
166{
167 struct inode *inode = dentry->d_inode;
168 int error;
169
170 if (!inode->i_op->removexattr)
171 return -EOPNOTSUPP;
172
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800173 error = xattr_permission(inode, name, MAY_WRITE);
174 if (error)
175 return error;
176
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800177 error = security_inode_removexattr(dentry, name);
178 if (error)
179 return error;
180
181 mutex_lock(&inode->i_mutex);
182 error = inode->i_op->removexattr(dentry, name);
183 mutex_unlock(&inode->i_mutex);
184
185 if (!error)
186 fsnotify_xattr(dentry);
187 return error;
188}
189EXPORT_SYMBOL_GPL(vfs_removexattr);
190
191
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192/*
193 * Extended attribute SET operations
194 */
195static long
196setxattr(struct dentry *d, char __user *name, void __user *value,
197 size_t size, int flags)
198{
199 int error;
200 void *kvalue = NULL;
201 char kname[XATTR_NAME_MAX + 1];
202
203 if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
204 return -EINVAL;
205
206 error = strncpy_from_user(kname, name, sizeof(kname));
207 if (error == 0 || error == sizeof(kname))
208 error = -ERANGE;
209 if (error < 0)
210 return error;
211
212 if (size) {
213 if (size > XATTR_SIZE_MAX)
214 return -E2BIG;
215 kvalue = kmalloc(size, GFP_KERNEL);
216 if (!kvalue)
217 return -ENOMEM;
218 if (copy_from_user(kvalue, value, size)) {
219 kfree(kvalue);
220 return -EFAULT;
221 }
222 }
223
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800224 error = vfs_setxattr(d, kname, kvalue, size, flags);
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800225 kfree(kvalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 return error;
227}
228
229asmlinkage long
230sys_setxattr(char __user *path, char __user *name, void __user *value,
231 size_t size, int flags)
232{
233 struct nameidata nd;
234 int error;
235
236 error = user_path_walk(path, &nd);
237 if (error)
238 return error;
239 error = setxattr(nd.dentry, name, value, size, flags);
240 path_release(&nd);
241 return error;
242}
243
244asmlinkage long
245sys_lsetxattr(char __user *path, char __user *name, void __user *value,
246 size_t size, int flags)
247{
248 struct nameidata nd;
249 int error;
250
251 error = user_path_walk_link(path, &nd);
252 if (error)
253 return error;
254 error = setxattr(nd.dentry, name, value, size, flags);
255 path_release(&nd);
256 return error;
257}
258
259asmlinkage long
260sys_fsetxattr(int fd, char __user *name, void __user *value,
261 size_t size, int flags)
262{
263 struct file *f;
Amy Griffis73241cc2005-11-03 16:00:25 +0000264 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 int error = -EBADF;
266
267 f = fget(fd);
268 if (!f)
269 return error;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800270 dentry = f->f_path.dentry;
Amy Griffis9c937dc2006-06-08 23:19:31 -0400271 audit_inode(NULL, dentry->d_inode);
Amy Griffis73241cc2005-11-03 16:00:25 +0000272 error = setxattr(dentry, name, value, size, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 fput(f);
274 return error;
275}
276
277/*
278 * Extended attribute GET operations
279 */
280static ssize_t
281getxattr(struct dentry *d, char __user *name, void __user *value, size_t size)
282{
283 ssize_t error;
284 void *kvalue = NULL;
285 char kname[XATTR_NAME_MAX + 1];
286
287 error = strncpy_from_user(kname, name, sizeof(kname));
288 if (error == 0 || error == sizeof(kname))
289 error = -ERANGE;
290 if (error < 0)
291 return error;
292
293 if (size) {
294 if (size > XATTR_SIZE_MAX)
295 size = XATTR_SIZE_MAX;
James Morrisd381d8a2005-10-30 14:59:22 -0800296 kvalue = kzalloc(size, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 if (!kvalue)
298 return -ENOMEM;
299 }
300
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800301 error = vfs_getxattr(d, kname, kvalue, size);
Stephen Smalleyf549d6c2005-09-03 15:55:18 -0700302 if (error > 0) {
303 if (size && copy_to_user(value, kvalue, error))
304 error = -EFAULT;
305 } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
306 /* The file system tried to returned a value bigger
307 than XATTR_SIZE_MAX bytes. Not possible. */
308 error = -E2BIG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 }
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800310 kfree(kvalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 return error;
312}
313
314asmlinkage ssize_t
315sys_getxattr(char __user *path, char __user *name, void __user *value,
316 size_t size)
317{
318 struct nameidata nd;
319 ssize_t error;
320
321 error = user_path_walk(path, &nd);
322 if (error)
323 return error;
324 error = getxattr(nd.dentry, name, value, size);
325 path_release(&nd);
326 return error;
327}
328
329asmlinkage ssize_t
330sys_lgetxattr(char __user *path, char __user *name, void __user *value,
331 size_t size)
332{
333 struct nameidata nd;
334 ssize_t error;
335
336 error = user_path_walk_link(path, &nd);
337 if (error)
338 return error;
339 error = getxattr(nd.dentry, name, value, size);
340 path_release(&nd);
341 return error;
342}
343
344asmlinkage ssize_t
345sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size)
346{
347 struct file *f;
348 ssize_t error = -EBADF;
349
350 f = fget(fd);
351 if (!f)
352 return error;
Amy Griffis510f4002007-02-13 14:14:41 -0500353 audit_inode(NULL, f->f_path.dentry->d_inode);
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800354 error = getxattr(f->f_path.dentry, name, value, size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 fput(f);
356 return error;
357}
358
359/*
360 * Extended attribute LIST operations
361 */
362static ssize_t
363listxattr(struct dentry *d, char __user *list, size_t size)
364{
365 ssize_t error;
366 char *klist = NULL;
367
368 if (size) {
369 if (size > XATTR_LIST_MAX)
370 size = XATTR_LIST_MAX;
371 klist = kmalloc(size, GFP_KERNEL);
372 if (!klist)
373 return -ENOMEM;
374 }
375
Bill Nottingham659564c2006-10-09 16:10:48 -0400376 error = vfs_listxattr(d, klist, size);
Stephen Smalleyf549d6c2005-09-03 15:55:18 -0700377 if (error > 0) {
378 if (size && copy_to_user(list, klist, error))
379 error = -EFAULT;
380 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
381 /* The file system tried to returned a list bigger
382 than XATTR_LIST_MAX bytes. Not possible. */
383 error = -E2BIG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 }
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800385 kfree(klist);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 return error;
387}
388
389asmlinkage ssize_t
390sys_listxattr(char __user *path, char __user *list, size_t size)
391{
392 struct nameidata nd;
393 ssize_t error;
394
395 error = user_path_walk(path, &nd);
396 if (error)
397 return error;
398 error = listxattr(nd.dentry, list, size);
399 path_release(&nd);
400 return error;
401}
402
403asmlinkage ssize_t
404sys_llistxattr(char __user *path, char __user *list, size_t size)
405{
406 struct nameidata nd;
407 ssize_t error;
408
409 error = user_path_walk_link(path, &nd);
410 if (error)
411 return error;
412 error = listxattr(nd.dentry, list, size);
413 path_release(&nd);
414 return error;
415}
416
417asmlinkage ssize_t
418sys_flistxattr(int fd, char __user *list, size_t size)
419{
420 struct file *f;
421 ssize_t error = -EBADF;
422
423 f = fget(fd);
424 if (!f)
425 return error;
Amy Griffis510f4002007-02-13 14:14:41 -0500426 audit_inode(NULL, f->f_path.dentry->d_inode);
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800427 error = listxattr(f->f_path.dentry, list, size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 fput(f);
429 return error;
430}
431
432/*
433 * Extended attribute REMOVE operations
434 */
435static long
436removexattr(struct dentry *d, char __user *name)
437{
438 int error;
439 char kname[XATTR_NAME_MAX + 1];
440
441 error = strncpy_from_user(kname, name, sizeof(kname));
442 if (error == 0 || error == sizeof(kname))
443 error = -ERANGE;
444 if (error < 0)
445 return error;
446
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800447 return vfs_removexattr(d, kname);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448}
449
450asmlinkage long
451sys_removexattr(char __user *path, char __user *name)
452{
453 struct nameidata nd;
454 int error;
455
456 error = user_path_walk(path, &nd);
457 if (error)
458 return error;
459 error = removexattr(nd.dentry, name);
460 path_release(&nd);
461 return error;
462}
463
464asmlinkage long
465sys_lremovexattr(char __user *path, char __user *name)
466{
467 struct nameidata nd;
468 int error;
469
470 error = user_path_walk_link(path, &nd);
471 if (error)
472 return error;
473 error = removexattr(nd.dentry, name);
474 path_release(&nd);
475 return error;
476}
477
478asmlinkage long
479sys_fremovexattr(int fd, char __user *name)
480{
481 struct file *f;
Amy Griffis73241cc2005-11-03 16:00:25 +0000482 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 int error = -EBADF;
484
485 f = fget(fd);
486 if (!f)
487 return error;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800488 dentry = f->f_path.dentry;
Amy Griffis9c937dc2006-06-08 23:19:31 -0400489 audit_inode(NULL, dentry->d_inode);
Amy Griffis73241cc2005-11-03 16:00:25 +0000490 error = removexattr(dentry, name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 fput(f);
492 return error;
493}
494
495
496static const char *
497strcmp_prefix(const char *a, const char *a_prefix)
498{
499 while (*a_prefix && *a == *a_prefix) {
500 a++;
501 a_prefix++;
502 }
503 return *a_prefix ? NULL : a;
504}
505
506/*
507 * In order to implement different sets of xattr operations for each xattr
508 * prefix with the generic xattr API, a filesystem should create a
509 * null-terminated array of struct xattr_handler (one for each prefix) and
510 * hang a pointer to it off of the s_xattr field of the superblock.
511 *
512 * The generic_fooxattr() functions will use this list to dispatch xattr
513 * operations to the correct xattr_handler.
514 */
515#define for_each_xattr_handler(handlers, handler) \
516 for ((handler) = *(handlers)++; \
517 (handler) != NULL; \
518 (handler) = *(handlers)++)
519
520/*
521 * Find the xattr_handler with the matching prefix.
522 */
523static struct xattr_handler *
524xattr_resolve_name(struct xattr_handler **handlers, const char **name)
525{
526 struct xattr_handler *handler;
527
528 if (!*name)
529 return NULL;
530
531 for_each_xattr_handler(handlers, handler) {
532 const char *n = strcmp_prefix(*name, handler->prefix);
533 if (n) {
534 *name = n;
535 break;
536 }
537 }
538 return handler;
539}
540
541/*
542 * Find the handler for the prefix and dispatch its get() operation.
543 */
544ssize_t
545generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
546{
547 struct xattr_handler *handler;
548 struct inode *inode = dentry->d_inode;
549
550 handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
551 if (!handler)
552 return -EOPNOTSUPP;
553 return handler->get(inode, name, buffer, size);
554}
555
556/*
557 * Combine the results of the list() operation from every xattr_handler in the
558 * list.
559 */
560ssize_t
561generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
562{
563 struct inode *inode = dentry->d_inode;
564 struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr;
565 unsigned int size = 0;
566
567 if (!buffer) {
568 for_each_xattr_handler(handlers, handler)
569 size += handler->list(inode, NULL, 0, NULL, 0);
570 } else {
571 char *buf = buffer;
572
573 for_each_xattr_handler(handlers, handler) {
574 size = handler->list(inode, buf, buffer_size, NULL, 0);
575 if (size > buffer_size)
576 return -ERANGE;
577 buf += size;
578 buffer_size -= size;
579 }
580 size = buf - buffer;
581 }
582 return size;
583}
584
585/*
586 * Find the handler for the prefix and dispatch its set() operation.
587 */
588int
589generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
590{
591 struct xattr_handler *handler;
592 struct inode *inode = dentry->d_inode;
593
594 if (size == 0)
595 value = ""; /* empty EA, do not remove */
596 handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
597 if (!handler)
598 return -EOPNOTSUPP;
599 return handler->set(inode, name, value, size, flags);
600}
601
602/*
603 * Find the handler for the prefix and dispatch its set() operation to remove
604 * any associated extended attribute.
605 */
606int
607generic_removexattr(struct dentry *dentry, const char *name)
608{
609 struct xattr_handler *handler;
610 struct inode *inode = dentry->d_inode;
611
612 handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
613 if (!handler)
614 return -EOPNOTSUPP;
615 return handler->set(inode, name, NULL, 0, XATTR_REPLACE);
616}
617
618EXPORT_SYMBOL(generic_getxattr);
619EXPORT_SYMBOL(generic_listxattr);
620EXPORT_SYMBOL(generic_setxattr);
621EXPORT_SYMBOL(generic_removexattr);