blob: 395635100f77a45784057546b0a0c4a490b03249 [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>
12#include <linux/smp_lock.h>
13#include <linux/file.h>
14#include <linux/xattr.h>
15#include <linux/namei.h>
16#include <linux/security.h>
17#include <linux/syscalls.h>
18#include <linux/module.h>
Robert Love0eeca282005-07-12 17:06:03 -040019#include <linux/fsnotify.h>
Amy Griffis73241cc2005-11-03 16:00:25 +000020#include <linux/audit.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <asm/uaccess.h>
22
Christoph Hellwig5be196e2006-01-09 20:51:55 -080023
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080024/*
25 * Check permissions for extended attribute access. This is a bit complicated
26 * because different namespaces have very different rules.
27 */
28static int
29xattr_permission(struct inode *inode, const char *name, int mask)
30{
31 /*
32 * We can never set or remove an extended attribute on a read-only
33 * filesystem or on an immutable / append-only inode.
34 */
35 if (mask & MAY_WRITE) {
36 if (IS_RDONLY(inode))
37 return -EROFS;
38 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
39 return -EPERM;
40 }
41
42 /*
43 * No restriction for security.* and system.* from the VFS. Decision
44 * on these is left to the underlying filesystem / security module.
45 */
46 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
47 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
48 return 0;
49
50 /*
51 * The trusted.* namespace can only accessed by a privilegued user.
52 */
53 if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
54 return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);
55
56 if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
57 if (!S_ISREG(inode->i_mode) &&
58 (!S_ISDIR(inode->i_mode) || inode->i_mode & S_ISVTX))
59 return -EPERM;
60 }
61
62 return permission(inode, mask, NULL);
63}
64
Christoph Hellwig5be196e2006-01-09 20:51:55 -080065int
66vfs_setxattr(struct dentry *dentry, char *name, void *value,
67 size_t size, int flags)
68{
69 struct inode *inode = dentry->d_inode;
70 int error;
71
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080072 error = xattr_permission(inode, name, MAY_WRITE);
73 if (error)
74 return error;
75
Christoph Hellwig5be196e2006-01-09 20:51:55 -080076 mutex_lock(&inode->i_mutex);
77 error = security_inode_setxattr(dentry, name, value, size, flags);
78 if (error)
79 goto out;
80 error = -EOPNOTSUPP;
81 if (inode->i_op->setxattr) {
82 error = inode->i_op->setxattr(dentry, name, value, size, flags);
83 if (!error) {
84 fsnotify_xattr(dentry);
85 security_inode_post_setxattr(dentry, name, value,
86 size, flags);
87 }
88 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080089 XATTR_SECURITY_PREFIX_LEN)) {
90 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
Christoph Hellwig5be196e2006-01-09 20:51:55 -080091 error = security_inode_setsecurity(inode, suffix, value,
92 size, flags);
93 if (!error)
94 fsnotify_xattr(dentry);
95 }
96out:
97 mutex_unlock(&inode->i_mutex);
98 return error;
99}
100EXPORT_SYMBOL_GPL(vfs_setxattr);
101
102ssize_t
103vfs_getxattr(struct dentry *dentry, char *name, void *value, size_t size)
104{
105 struct inode *inode = dentry->d_inode;
106 int error;
107
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800108 error = xattr_permission(inode, name, MAY_READ);
109 if (error)
110 return error;
111
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800112 error = security_inode_getxattr(dentry, name);
113 if (error)
114 return error;
115
116 if (inode->i_op->getxattr)
117 error = inode->i_op->getxattr(dentry, name, value, size);
118 else
119 error = -EOPNOTSUPP;
120
121 if (!strncmp(name, XATTR_SECURITY_PREFIX,
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800122 XATTR_SECURITY_PREFIX_LEN)) {
123 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800124 int ret = security_inode_getsecurity(inode, suffix, value,
125 size, error);
126 /*
127 * Only overwrite the return value if a security module
128 * is actually active.
129 */
130 if (ret != -EOPNOTSUPP)
131 error = ret;
132 }
133
134 return error;
135}
136EXPORT_SYMBOL_GPL(vfs_getxattr);
137
Bill Nottingham659564c2006-10-09 16:10:48 -0400138ssize_t
139vfs_listxattr(struct dentry *d, char *list, size_t size)
140{
141 ssize_t error;
142
143 error = security_inode_listxattr(d);
144 if (error)
145 return error;
146 error = -EOPNOTSUPP;
147 if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
148 error = d->d_inode->i_op->listxattr(d, list, size);
149 } else {
150 error = security_inode_listsecurity(d->d_inode, list, size);
151 if (size && error > size)
152 error = -ERANGE;
153 }
154 return error;
155}
156EXPORT_SYMBOL_GPL(vfs_listxattr);
157
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800158int
159vfs_removexattr(struct dentry *dentry, char *name)
160{
161 struct inode *inode = dentry->d_inode;
162 int error;
163
164 if (!inode->i_op->removexattr)
165 return -EOPNOTSUPP;
166
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800167 error = xattr_permission(inode, name, MAY_WRITE);
168 if (error)
169 return error;
170
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800171 error = security_inode_removexattr(dentry, name);
172 if (error)
173 return error;
174
175 mutex_lock(&inode->i_mutex);
176 error = inode->i_op->removexattr(dentry, name);
177 mutex_unlock(&inode->i_mutex);
178
179 if (!error)
180 fsnotify_xattr(dentry);
181 return error;
182}
183EXPORT_SYMBOL_GPL(vfs_removexattr);
184
185
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186/*
187 * Extended attribute SET operations
188 */
189static long
190setxattr(struct dentry *d, char __user *name, void __user *value,
191 size_t size, int flags)
192{
193 int error;
194 void *kvalue = NULL;
195 char kname[XATTR_NAME_MAX + 1];
196
197 if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
198 return -EINVAL;
199
200 error = strncpy_from_user(kname, name, sizeof(kname));
201 if (error == 0 || error == sizeof(kname))
202 error = -ERANGE;
203 if (error < 0)
204 return error;
205
206 if (size) {
207 if (size > XATTR_SIZE_MAX)
208 return -E2BIG;
209 kvalue = kmalloc(size, GFP_KERNEL);
210 if (!kvalue)
211 return -ENOMEM;
212 if (copy_from_user(kvalue, value, size)) {
213 kfree(kvalue);
214 return -EFAULT;
215 }
216 }
217
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800218 error = vfs_setxattr(d, kname, kvalue, size, flags);
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800219 kfree(kvalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 return error;
221}
222
223asmlinkage long
224sys_setxattr(char __user *path, char __user *name, void __user *value,
225 size_t size, int flags)
226{
227 struct nameidata nd;
228 int error;
229
230 error = user_path_walk(path, &nd);
231 if (error)
232 return error;
233 error = setxattr(nd.dentry, name, value, size, flags);
234 path_release(&nd);
235 return error;
236}
237
238asmlinkage long
239sys_lsetxattr(char __user *path, char __user *name, void __user *value,
240 size_t size, int flags)
241{
242 struct nameidata nd;
243 int error;
244
245 error = user_path_walk_link(path, &nd);
246 if (error)
247 return error;
248 error = setxattr(nd.dentry, name, value, size, flags);
249 path_release(&nd);
250 return error;
251}
252
253asmlinkage long
254sys_fsetxattr(int fd, char __user *name, void __user *value,
255 size_t size, int flags)
256{
257 struct file *f;
Amy Griffis73241cc2005-11-03 16:00:25 +0000258 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 int error = -EBADF;
260
261 f = fget(fd);
262 if (!f)
263 return error;
Amy Griffis73241cc2005-11-03 16:00:25 +0000264 dentry = f->f_dentry;
Amy Griffis9c937dc2006-06-08 23:19:31 -0400265 audit_inode(NULL, dentry->d_inode);
Amy Griffis73241cc2005-11-03 16:00:25 +0000266 error = setxattr(dentry, name, value, size, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 fput(f);
268 return error;
269}
270
271/*
272 * Extended attribute GET operations
273 */
274static ssize_t
275getxattr(struct dentry *d, char __user *name, void __user *value, size_t size)
276{
277 ssize_t error;
278 void *kvalue = NULL;
279 char kname[XATTR_NAME_MAX + 1];
280
281 error = strncpy_from_user(kname, name, sizeof(kname));
282 if (error == 0 || error == sizeof(kname))
283 error = -ERANGE;
284 if (error < 0)
285 return error;
286
287 if (size) {
288 if (size > XATTR_SIZE_MAX)
289 size = XATTR_SIZE_MAX;
James Morrisd381d8a2005-10-30 14:59:22 -0800290 kvalue = kzalloc(size, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 if (!kvalue)
292 return -ENOMEM;
293 }
294
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800295 error = vfs_getxattr(d, kname, kvalue, size);
Stephen Smalleyf549d6c2005-09-03 15:55:18 -0700296 if (error > 0) {
297 if (size && copy_to_user(value, kvalue, error))
298 error = -EFAULT;
299 } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
300 /* The file system tried to returned a value bigger
301 than XATTR_SIZE_MAX bytes. Not possible. */
302 error = -E2BIG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 }
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800304 kfree(kvalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 return error;
306}
307
308asmlinkage ssize_t
309sys_getxattr(char __user *path, char __user *name, void __user *value,
310 size_t size)
311{
312 struct nameidata nd;
313 ssize_t error;
314
315 error = user_path_walk(path, &nd);
316 if (error)
317 return error;
318 error = getxattr(nd.dentry, name, value, size);
319 path_release(&nd);
320 return error;
321}
322
323asmlinkage ssize_t
324sys_lgetxattr(char __user *path, char __user *name, void __user *value,
325 size_t size)
326{
327 struct nameidata nd;
328 ssize_t error;
329
330 error = user_path_walk_link(path, &nd);
331 if (error)
332 return error;
333 error = getxattr(nd.dentry, name, value, size);
334 path_release(&nd);
335 return error;
336}
337
338asmlinkage ssize_t
339sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size)
340{
341 struct file *f;
342 ssize_t error = -EBADF;
343
344 f = fget(fd);
345 if (!f)
346 return error;
347 error = getxattr(f->f_dentry, name, value, size);
348 fput(f);
349 return error;
350}
351
352/*
353 * Extended attribute LIST operations
354 */
355static ssize_t
356listxattr(struct dentry *d, char __user *list, size_t size)
357{
358 ssize_t error;
359 char *klist = NULL;
360
361 if (size) {
362 if (size > XATTR_LIST_MAX)
363 size = XATTR_LIST_MAX;
364 klist = kmalloc(size, GFP_KERNEL);
365 if (!klist)
366 return -ENOMEM;
367 }
368
Bill Nottingham659564c2006-10-09 16:10:48 -0400369 error = vfs_listxattr(d, klist, size);
Stephen Smalleyf549d6c2005-09-03 15:55:18 -0700370 if (error > 0) {
371 if (size && copy_to_user(list, klist, error))
372 error = -EFAULT;
373 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
374 /* The file system tried to returned a list bigger
375 than XATTR_LIST_MAX bytes. Not possible. */
376 error = -E2BIG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377 }
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800378 kfree(klist);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 return error;
380}
381
382asmlinkage ssize_t
383sys_listxattr(char __user *path, char __user *list, size_t size)
384{
385 struct nameidata nd;
386 ssize_t error;
387
388 error = user_path_walk(path, &nd);
389 if (error)
390 return error;
391 error = listxattr(nd.dentry, list, size);
392 path_release(&nd);
393 return error;
394}
395
396asmlinkage ssize_t
397sys_llistxattr(char __user *path, char __user *list, size_t size)
398{
399 struct nameidata nd;
400 ssize_t error;
401
402 error = user_path_walk_link(path, &nd);
403 if (error)
404 return error;
405 error = listxattr(nd.dentry, list, size);
406 path_release(&nd);
407 return error;
408}
409
410asmlinkage ssize_t
411sys_flistxattr(int fd, char __user *list, size_t size)
412{
413 struct file *f;
414 ssize_t error = -EBADF;
415
416 f = fget(fd);
417 if (!f)
418 return error;
419 error = listxattr(f->f_dentry, list, size);
420 fput(f);
421 return error;
422}
423
424/*
425 * Extended attribute REMOVE operations
426 */
427static long
428removexattr(struct dentry *d, char __user *name)
429{
430 int error;
431 char kname[XATTR_NAME_MAX + 1];
432
433 error = strncpy_from_user(kname, name, sizeof(kname));
434 if (error == 0 || error == sizeof(kname))
435 error = -ERANGE;
436 if (error < 0)
437 return error;
438
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800439 return vfs_removexattr(d, kname);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440}
441
442asmlinkage long
443sys_removexattr(char __user *path, char __user *name)
444{
445 struct nameidata nd;
446 int error;
447
448 error = user_path_walk(path, &nd);
449 if (error)
450 return error;
451 error = removexattr(nd.dentry, name);
452 path_release(&nd);
453 return error;
454}
455
456asmlinkage long
457sys_lremovexattr(char __user *path, char __user *name)
458{
459 struct nameidata nd;
460 int error;
461
462 error = user_path_walk_link(path, &nd);
463 if (error)
464 return error;
465 error = removexattr(nd.dentry, name);
466 path_release(&nd);
467 return error;
468}
469
470asmlinkage long
471sys_fremovexattr(int fd, char __user *name)
472{
473 struct file *f;
Amy Griffis73241cc2005-11-03 16:00:25 +0000474 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 int error = -EBADF;
476
477 f = fget(fd);
478 if (!f)
479 return error;
Amy Griffis73241cc2005-11-03 16:00:25 +0000480 dentry = f->f_dentry;
Amy Griffis9c937dc2006-06-08 23:19:31 -0400481 audit_inode(NULL, dentry->d_inode);
Amy Griffis73241cc2005-11-03 16:00:25 +0000482 error = removexattr(dentry, name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 fput(f);
484 return error;
485}
486
487
488static const char *
489strcmp_prefix(const char *a, const char *a_prefix)
490{
491 while (*a_prefix && *a == *a_prefix) {
492 a++;
493 a_prefix++;
494 }
495 return *a_prefix ? NULL : a;
496}
497
498/*
499 * In order to implement different sets of xattr operations for each xattr
500 * prefix with the generic xattr API, a filesystem should create a
501 * null-terminated array of struct xattr_handler (one for each prefix) and
502 * hang a pointer to it off of the s_xattr field of the superblock.
503 *
504 * The generic_fooxattr() functions will use this list to dispatch xattr
505 * operations to the correct xattr_handler.
506 */
507#define for_each_xattr_handler(handlers, handler) \
508 for ((handler) = *(handlers)++; \
509 (handler) != NULL; \
510 (handler) = *(handlers)++)
511
512/*
513 * Find the xattr_handler with the matching prefix.
514 */
515static struct xattr_handler *
516xattr_resolve_name(struct xattr_handler **handlers, const char **name)
517{
518 struct xattr_handler *handler;
519
520 if (!*name)
521 return NULL;
522
523 for_each_xattr_handler(handlers, handler) {
524 const char *n = strcmp_prefix(*name, handler->prefix);
525 if (n) {
526 *name = n;
527 break;
528 }
529 }
530 return handler;
531}
532
533/*
534 * Find the handler for the prefix and dispatch its get() operation.
535 */
536ssize_t
537generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
538{
539 struct xattr_handler *handler;
540 struct inode *inode = dentry->d_inode;
541
542 handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
543 if (!handler)
544 return -EOPNOTSUPP;
545 return handler->get(inode, name, buffer, size);
546}
547
548/*
549 * Combine the results of the list() operation from every xattr_handler in the
550 * list.
551 */
552ssize_t
553generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
554{
555 struct inode *inode = dentry->d_inode;
556 struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr;
557 unsigned int size = 0;
558
559 if (!buffer) {
560 for_each_xattr_handler(handlers, handler)
561 size += handler->list(inode, NULL, 0, NULL, 0);
562 } else {
563 char *buf = buffer;
564
565 for_each_xattr_handler(handlers, handler) {
566 size = handler->list(inode, buf, buffer_size, NULL, 0);
567 if (size > buffer_size)
568 return -ERANGE;
569 buf += size;
570 buffer_size -= size;
571 }
572 size = buf - buffer;
573 }
574 return size;
575}
576
577/*
578 * Find the handler for the prefix and dispatch its set() operation.
579 */
580int
581generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
582{
583 struct xattr_handler *handler;
584 struct inode *inode = dentry->d_inode;
585
586 if (size == 0)
587 value = ""; /* empty EA, do not remove */
588 handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
589 if (!handler)
590 return -EOPNOTSUPP;
591 return handler->set(inode, name, value, size, flags);
592}
593
594/*
595 * Find the handler for the prefix and dispatch its set() operation to remove
596 * any associated extended attribute.
597 */
598int
599generic_removexattr(struct dentry *dentry, const char *name)
600{
601 struct xattr_handler *handler;
602 struct inode *inode = dentry->d_inode;
603
604 handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
605 if (!handler)
606 return -EOPNOTSUPP;
607 return handler->set(inode, name, NULL, 0, XATTR_REPLACE);
608}
609
610EXPORT_SYMBOL(generic_getxattr);
611EXPORT_SYMBOL(generic_listxattr);
612EXPORT_SYMBOL(generic_setxattr);
613EXPORT_SYMBOL(generic_removexattr);