Commit | Line | Data |
---|---|---|
1da177e4 LT |
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/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> | |
0eeca283 | 19 | #include <linux/fsnotify.h> |
1da177e4 LT |
20 | #include <asm/uaccess.h> |
21 | ||
5be196e5 | 22 | |
e0ad7b07 | 23 | /* |
24 | * Check permissions for extended attribute access. This is a bit complicated | |
25 | * because different namespaces have very different rules. | |
26 | */ | |
27 | static int | |
28 | xattr_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 | /* | |
50 | * The trusted.* namespace can only accessed by a privilegued user. | |
51 | */ | |
52 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) | |
53 | return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM); | |
54 | ||
55 | if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) { | |
56 | if (!S_ISREG(inode->i_mode) && | |
57 | (!S_ISDIR(inode->i_mode) || inode->i_mode & S_ISVTX)) | |
58 | return -EPERM; | |
59 | } | |
60 | ||
61 | return permission(inode, mask, NULL); | |
62 | } | |
63 | ||
5be196e5 CH |
64 | int |
65 | vfs_setxattr(struct dentry *dentry, char *name, void *value, | |
66 | size_t size, int flags) | |
67 | { | |
68 | struct inode *inode = dentry->d_inode; | |
69 | int error; | |
70 | ||
e0ad7b07 | 71 | error = xattr_permission(inode, name, MAY_WRITE); |
72 | if (error) | |
73 | return error; | |
74 | ||
5be196e5 CH |
75 | mutex_lock(&inode->i_mutex); |
76 | error = security_inode_setxattr(dentry, name, value, size, flags); | |
77 | if (error) | |
78 | goto out; | |
79 | error = -EOPNOTSUPP; | |
80 | if (inode->i_op->setxattr) { | |
81 | error = inode->i_op->setxattr(dentry, name, value, size, flags); | |
82 | if (!error) { | |
83 | fsnotify_xattr(dentry); | |
84 | security_inode_post_setxattr(dentry, name, value, | |
85 | size, flags); | |
86 | } | |
87 | } else if (!strncmp(name, XATTR_SECURITY_PREFIX, | |
e0ad7b07 | 88 | XATTR_SECURITY_PREFIX_LEN)) { |
89 | const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; | |
5be196e5 CH |
90 | error = security_inode_setsecurity(inode, suffix, value, |
91 | size, flags); | |
92 | if (!error) | |
93 | fsnotify_xattr(dentry); | |
94 | } | |
95 | out: | |
96 | mutex_unlock(&inode->i_mutex); | |
97 | return error; | |
98 | } | |
99 | EXPORT_SYMBOL_GPL(vfs_setxattr); | |
100 | ||
101 | ssize_t | |
102 | vfs_getxattr(struct dentry *dentry, char *name, void *value, size_t size) | |
103 | { | |
104 | struct inode *inode = dentry->d_inode; | |
105 | int error; | |
106 | ||
e0ad7b07 | 107 | error = xattr_permission(inode, name, MAY_READ); |
108 | if (error) | |
109 | return error; | |
110 | ||
5be196e5 CH |
111 | error = security_inode_getxattr(dentry, name); |
112 | if (error) | |
113 | return error; | |
114 | ||
115 | if (inode->i_op->getxattr) | |
116 | error = inode->i_op->getxattr(dentry, name, value, size); | |
117 | else | |
118 | error = -EOPNOTSUPP; | |
119 | ||
120 | if (!strncmp(name, XATTR_SECURITY_PREFIX, | |
e0ad7b07 | 121 | XATTR_SECURITY_PREFIX_LEN)) { |
122 | const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; | |
5be196e5 CH |
123 | int ret = security_inode_getsecurity(inode, suffix, value, |
124 | size, error); | |
125 | /* | |
126 | * Only overwrite the return value if a security module | |
127 | * is actually active. | |
128 | */ | |
129 | if (ret != -EOPNOTSUPP) | |
130 | error = ret; | |
131 | } | |
132 | ||
133 | return error; | |
134 | } | |
135 | EXPORT_SYMBOL_GPL(vfs_getxattr); | |
136 | ||
137 | int | |
138 | vfs_removexattr(struct dentry *dentry, char *name) | |
139 | { | |
140 | struct inode *inode = dentry->d_inode; | |
141 | int error; | |
142 | ||
143 | if (!inode->i_op->removexattr) | |
144 | return -EOPNOTSUPP; | |
145 | ||
e0ad7b07 | 146 | error = xattr_permission(inode, name, MAY_WRITE); |
147 | if (error) | |
148 | return error; | |
149 | ||
5be196e5 CH |
150 | error = security_inode_removexattr(dentry, name); |
151 | if (error) | |
152 | return error; | |
153 | ||
154 | mutex_lock(&inode->i_mutex); | |
155 | error = inode->i_op->removexattr(dentry, name); | |
156 | mutex_unlock(&inode->i_mutex); | |
157 | ||
158 | if (!error) | |
159 | fsnotify_xattr(dentry); | |
160 | return error; | |
161 | } | |
162 | EXPORT_SYMBOL_GPL(vfs_removexattr); | |
163 | ||
164 | ||
1da177e4 LT |
165 | /* |
166 | * Extended attribute SET operations | |
167 | */ | |
168 | static long | |
169 | setxattr(struct dentry *d, char __user *name, void __user *value, | |
170 | size_t size, int flags) | |
171 | { | |
172 | int error; | |
173 | void *kvalue = NULL; | |
174 | char kname[XATTR_NAME_MAX + 1]; | |
175 | ||
176 | if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) | |
177 | return -EINVAL; | |
178 | ||
179 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
180 | if (error == 0 || error == sizeof(kname)) | |
181 | error = -ERANGE; | |
182 | if (error < 0) | |
183 | return error; | |
184 | ||
185 | if (size) { | |
186 | if (size > XATTR_SIZE_MAX) | |
187 | return -E2BIG; | |
188 | kvalue = kmalloc(size, GFP_KERNEL); | |
189 | if (!kvalue) | |
190 | return -ENOMEM; | |
191 | if (copy_from_user(kvalue, value, size)) { | |
192 | kfree(kvalue); | |
193 | return -EFAULT; | |
194 | } | |
195 | } | |
196 | ||
5be196e5 | 197 | error = vfs_setxattr(d, kname, kvalue, size, flags); |
f99d49ad | 198 | kfree(kvalue); |
1da177e4 LT |
199 | return error; |
200 | } | |
201 | ||
202 | asmlinkage long | |
203 | sys_setxattr(char __user *path, char __user *name, void __user *value, | |
204 | size_t size, int flags) | |
205 | { | |
206 | struct nameidata nd; | |
207 | int error; | |
208 | ||
209 | error = user_path_walk(path, &nd); | |
210 | if (error) | |
211 | return error; | |
212 | error = setxattr(nd.dentry, name, value, size, flags); | |
213 | path_release(&nd); | |
214 | return error; | |
215 | } | |
216 | ||
217 | asmlinkage long | |
218 | sys_lsetxattr(char __user *path, char __user *name, void __user *value, | |
219 | size_t size, int flags) | |
220 | { | |
221 | struct nameidata nd; | |
222 | int error; | |
223 | ||
224 | error = user_path_walk_link(path, &nd); | |
225 | if (error) | |
226 | return error; | |
227 | error = setxattr(nd.dentry, name, value, size, flags); | |
228 | path_release(&nd); | |
229 | return error; | |
230 | } | |
231 | ||
232 | asmlinkage long | |
233 | sys_fsetxattr(int fd, char __user *name, void __user *value, | |
234 | size_t size, int flags) | |
235 | { | |
236 | struct file *f; | |
237 | int error = -EBADF; | |
238 | ||
239 | f = fget(fd); | |
240 | if (!f) | |
241 | return error; | |
242 | error = setxattr(f->f_dentry, name, value, size, flags); | |
243 | fput(f); | |
244 | return error; | |
245 | } | |
246 | ||
247 | /* | |
248 | * Extended attribute GET operations | |
249 | */ | |
250 | static ssize_t | |
251 | getxattr(struct dentry *d, char __user *name, void __user *value, size_t size) | |
252 | { | |
253 | ssize_t error; | |
254 | void *kvalue = NULL; | |
255 | char kname[XATTR_NAME_MAX + 1]; | |
256 | ||
257 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
258 | if (error == 0 || error == sizeof(kname)) | |
259 | error = -ERANGE; | |
260 | if (error < 0) | |
261 | return error; | |
262 | ||
263 | if (size) { | |
264 | if (size > XATTR_SIZE_MAX) | |
265 | size = XATTR_SIZE_MAX; | |
d381d8a9 | 266 | kvalue = kzalloc(size, GFP_KERNEL); |
1da177e4 LT |
267 | if (!kvalue) |
268 | return -ENOMEM; | |
269 | } | |
270 | ||
5be196e5 | 271 | error = vfs_getxattr(d, kname, kvalue, size); |
f549d6c1 SS |
272 | if (error > 0) { |
273 | if (size && copy_to_user(value, kvalue, error)) | |
274 | error = -EFAULT; | |
275 | } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { | |
276 | /* The file system tried to returned a value bigger | |
277 | than XATTR_SIZE_MAX bytes. Not possible. */ | |
278 | error = -E2BIG; | |
1da177e4 | 279 | } |
f99d49ad | 280 | kfree(kvalue); |
1da177e4 LT |
281 | return error; |
282 | } | |
283 | ||
284 | asmlinkage ssize_t | |
285 | sys_getxattr(char __user *path, char __user *name, void __user *value, | |
286 | size_t size) | |
287 | { | |
288 | struct nameidata nd; | |
289 | ssize_t error; | |
290 | ||
291 | error = user_path_walk(path, &nd); | |
292 | if (error) | |
293 | return error; | |
294 | error = getxattr(nd.dentry, name, value, size); | |
295 | path_release(&nd); | |
296 | return error; | |
297 | } | |
298 | ||
299 | asmlinkage ssize_t | |
300 | sys_lgetxattr(char __user *path, char __user *name, void __user *value, | |
301 | size_t size) | |
302 | { | |
303 | struct nameidata nd; | |
304 | ssize_t error; | |
305 | ||
306 | error = user_path_walk_link(path, &nd); | |
307 | if (error) | |
308 | return error; | |
309 | error = getxattr(nd.dentry, name, value, size); | |
310 | path_release(&nd); | |
311 | return error; | |
312 | } | |
313 | ||
314 | asmlinkage ssize_t | |
315 | sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size) | |
316 | { | |
317 | struct file *f; | |
318 | ssize_t error = -EBADF; | |
319 | ||
320 | f = fget(fd); | |
321 | if (!f) | |
322 | return error; | |
323 | error = getxattr(f->f_dentry, name, value, size); | |
324 | fput(f); | |
325 | return error; | |
326 | } | |
327 | ||
328 | /* | |
329 | * Extended attribute LIST operations | |
330 | */ | |
331 | static ssize_t | |
332 | listxattr(struct dentry *d, char __user *list, size_t size) | |
333 | { | |
334 | ssize_t error; | |
335 | char *klist = NULL; | |
336 | ||
337 | if (size) { | |
338 | if (size > XATTR_LIST_MAX) | |
339 | size = XATTR_LIST_MAX; | |
340 | klist = kmalloc(size, GFP_KERNEL); | |
341 | if (!klist) | |
342 | return -ENOMEM; | |
343 | } | |
344 | ||
f549d6c1 SS |
345 | error = security_inode_listxattr(d); |
346 | if (error) | |
347 | goto out; | |
1da177e4 LT |
348 | error = -EOPNOTSUPP; |
349 | if (d->d_inode->i_op && d->d_inode->i_op->listxattr) { | |
1da177e4 | 350 | error = d->d_inode->i_op->listxattr(d, klist, size); |
f549d6c1 SS |
351 | } else { |
352 | error = security_inode_listsecurity(d->d_inode, klist, size); | |
894ec870 | 353 | if (size && error > size) |
f549d6c1 SS |
354 | error = -ERANGE; |
355 | } | |
356 | if (error > 0) { | |
357 | if (size && copy_to_user(list, klist, error)) | |
358 | error = -EFAULT; | |
359 | } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { | |
360 | /* The file system tried to returned a list bigger | |
361 | than XATTR_LIST_MAX bytes. Not possible. */ | |
362 | error = -E2BIG; | |
1da177e4 LT |
363 | } |
364 | out: | |
f99d49ad | 365 | kfree(klist); |
1da177e4 LT |
366 | return error; |
367 | } | |
368 | ||
369 | asmlinkage ssize_t | |
370 | sys_listxattr(char __user *path, char __user *list, size_t size) | |
371 | { | |
372 | struct nameidata nd; | |
373 | ssize_t error; | |
374 | ||
375 | error = user_path_walk(path, &nd); | |
376 | if (error) | |
377 | return error; | |
378 | error = listxattr(nd.dentry, list, size); | |
379 | path_release(&nd); | |
380 | return error; | |
381 | } | |
382 | ||
383 | asmlinkage ssize_t | |
384 | sys_llistxattr(char __user *path, char __user *list, size_t size) | |
385 | { | |
386 | struct nameidata nd; | |
387 | ssize_t error; | |
388 | ||
389 | error = user_path_walk_link(path, &nd); | |
390 | if (error) | |
391 | return error; | |
392 | error = listxattr(nd.dentry, list, size); | |
393 | path_release(&nd); | |
394 | return error; | |
395 | } | |
396 | ||
397 | asmlinkage ssize_t | |
398 | sys_flistxattr(int fd, char __user *list, size_t size) | |
399 | { | |
400 | struct file *f; | |
401 | ssize_t error = -EBADF; | |
402 | ||
403 | f = fget(fd); | |
404 | if (!f) | |
405 | return error; | |
406 | error = listxattr(f->f_dentry, list, size); | |
407 | fput(f); | |
408 | return error; | |
409 | } | |
410 | ||
411 | /* | |
412 | * Extended attribute REMOVE operations | |
413 | */ | |
414 | static long | |
415 | removexattr(struct dentry *d, char __user *name) | |
416 | { | |
417 | int error; | |
418 | char kname[XATTR_NAME_MAX + 1]; | |
419 | ||
420 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
421 | if (error == 0 || error == sizeof(kname)) | |
422 | error = -ERANGE; | |
423 | if (error < 0) | |
424 | return error; | |
425 | ||
5be196e5 | 426 | return vfs_removexattr(d, kname); |
1da177e4 LT |
427 | } |
428 | ||
429 | asmlinkage long | |
430 | sys_removexattr(char __user *path, char __user *name) | |
431 | { | |
432 | struct nameidata nd; | |
433 | int error; | |
434 | ||
435 | error = user_path_walk(path, &nd); | |
436 | if (error) | |
437 | return error; | |
438 | error = removexattr(nd.dentry, name); | |
439 | path_release(&nd); | |
440 | return error; | |
441 | } | |
442 | ||
443 | asmlinkage long | |
444 | sys_lremovexattr(char __user *path, char __user *name) | |
445 | { | |
446 | struct nameidata nd; | |
447 | int error; | |
448 | ||
449 | error = user_path_walk_link(path, &nd); | |
450 | if (error) | |
451 | return error; | |
452 | error = removexattr(nd.dentry, name); | |
453 | path_release(&nd); | |
454 | return error; | |
455 | } | |
456 | ||
457 | asmlinkage long | |
458 | sys_fremovexattr(int fd, char __user *name) | |
459 | { | |
460 | struct file *f; | |
461 | int error = -EBADF; | |
462 | ||
463 | f = fget(fd); | |
464 | if (!f) | |
465 | return error; | |
466 | error = removexattr(f->f_dentry, name); | |
467 | fput(f); | |
468 | return error; | |
469 | } | |
470 | ||
471 | ||
472 | static const char * | |
473 | strcmp_prefix(const char *a, const char *a_prefix) | |
474 | { | |
475 | while (*a_prefix && *a == *a_prefix) { | |
476 | a++; | |
477 | a_prefix++; | |
478 | } | |
479 | return *a_prefix ? NULL : a; | |
480 | } | |
481 | ||
482 | /* | |
483 | * In order to implement different sets of xattr operations for each xattr | |
484 | * prefix with the generic xattr API, a filesystem should create a | |
485 | * null-terminated array of struct xattr_handler (one for each prefix) and | |
486 | * hang a pointer to it off of the s_xattr field of the superblock. | |
487 | * | |
488 | * The generic_fooxattr() functions will use this list to dispatch xattr | |
489 | * operations to the correct xattr_handler. | |
490 | */ | |
491 | #define for_each_xattr_handler(handlers, handler) \ | |
492 | for ((handler) = *(handlers)++; \ | |
493 | (handler) != NULL; \ | |
494 | (handler) = *(handlers)++) | |
495 | ||
496 | /* | |
497 | * Find the xattr_handler with the matching prefix. | |
498 | */ | |
499 | static struct xattr_handler * | |
500 | xattr_resolve_name(struct xattr_handler **handlers, const char **name) | |
501 | { | |
502 | struct xattr_handler *handler; | |
503 | ||
504 | if (!*name) | |
505 | return NULL; | |
506 | ||
507 | for_each_xattr_handler(handlers, handler) { | |
508 | const char *n = strcmp_prefix(*name, handler->prefix); | |
509 | if (n) { | |
510 | *name = n; | |
511 | break; | |
512 | } | |
513 | } | |
514 | return handler; | |
515 | } | |
516 | ||
517 | /* | |
518 | * Find the handler for the prefix and dispatch its get() operation. | |
519 | */ | |
520 | ssize_t | |
521 | generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) | |
522 | { | |
523 | struct xattr_handler *handler; | |
524 | struct inode *inode = dentry->d_inode; | |
525 | ||
526 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
527 | if (!handler) | |
528 | return -EOPNOTSUPP; | |
529 | return handler->get(inode, name, buffer, size); | |
530 | } | |
531 | ||
532 | /* | |
533 | * Combine the results of the list() operation from every xattr_handler in the | |
534 | * list. | |
535 | */ | |
536 | ssize_t | |
537 | generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) | |
538 | { | |
539 | struct inode *inode = dentry->d_inode; | |
540 | struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr; | |
541 | unsigned int size = 0; | |
542 | ||
543 | if (!buffer) { | |
544 | for_each_xattr_handler(handlers, handler) | |
545 | size += handler->list(inode, NULL, 0, NULL, 0); | |
546 | } else { | |
547 | char *buf = buffer; | |
548 | ||
549 | for_each_xattr_handler(handlers, handler) { | |
550 | size = handler->list(inode, buf, buffer_size, NULL, 0); | |
551 | if (size > buffer_size) | |
552 | return -ERANGE; | |
553 | buf += size; | |
554 | buffer_size -= size; | |
555 | } | |
556 | size = buf - buffer; | |
557 | } | |
558 | return size; | |
559 | } | |
560 | ||
561 | /* | |
562 | * Find the handler for the prefix and dispatch its set() operation. | |
563 | */ | |
564 | int | |
565 | generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) | |
566 | { | |
567 | struct xattr_handler *handler; | |
568 | struct inode *inode = dentry->d_inode; | |
569 | ||
570 | if (size == 0) | |
571 | value = ""; /* empty EA, do not remove */ | |
572 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
573 | if (!handler) | |
574 | return -EOPNOTSUPP; | |
575 | return handler->set(inode, name, value, size, flags); | |
576 | } | |
577 | ||
578 | /* | |
579 | * Find the handler for the prefix and dispatch its set() operation to remove | |
580 | * any associated extended attribute. | |
581 | */ | |
582 | int | |
583 | generic_removexattr(struct dentry *dentry, const char *name) | |
584 | { | |
585 | struct xattr_handler *handler; | |
586 | struct inode *inode = dentry->d_inode; | |
587 | ||
588 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
589 | if (!handler) | |
590 | return -EOPNOTSUPP; | |
591 | return handler->set(inode, name, NULL, 0, XATTR_REPLACE); | |
592 | } | |
593 | ||
594 | EXPORT_SYMBOL(generic_getxattr); | |
595 | EXPORT_SYMBOL(generic_listxattr); | |
596 | EXPORT_SYMBOL(generic_setxattr); | |
597 | EXPORT_SYMBOL(generic_removexattr); |