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 | ||
22 | /* | |
23 | * Extended attribute SET operations | |
24 | */ | |
25 | static long | |
26 | setxattr(struct dentry *d, char __user *name, void __user *value, | |
27 | size_t size, int flags) | |
28 | { | |
29 | int error; | |
30 | void *kvalue = NULL; | |
31 | char kname[XATTR_NAME_MAX + 1]; | |
32 | ||
33 | if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) | |
34 | return -EINVAL; | |
35 | ||
36 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
37 | if (error == 0 || error == sizeof(kname)) | |
38 | error = -ERANGE; | |
39 | if (error < 0) | |
40 | return error; | |
41 | ||
42 | if (size) { | |
43 | if (size > XATTR_SIZE_MAX) | |
44 | return -E2BIG; | |
45 | kvalue = kmalloc(size, GFP_KERNEL); | |
46 | if (!kvalue) | |
47 | return -ENOMEM; | |
48 | if (copy_from_user(kvalue, value, size)) { | |
49 | kfree(kvalue); | |
50 | return -EFAULT; | |
51 | } | |
52 | } | |
53 | ||
f549d6c1 SS |
54 | down(&d->d_inode->i_sem); |
55 | error = security_inode_setxattr(d, kname, kvalue, size, flags); | |
56 | if (error) | |
57 | goto out; | |
1da177e4 LT |
58 | error = -EOPNOTSUPP; |
59 | if (d->d_inode->i_op && d->d_inode->i_op->setxattr) { | |
f549d6c1 SS |
60 | error = d->d_inode->i_op->setxattr(d, kname, kvalue, |
61 | size, flags); | |
0eeca283 RL |
62 | if (!error) { |
63 | fsnotify_xattr(d); | |
f549d6c1 SS |
64 | security_inode_post_setxattr(d, kname, kvalue, |
65 | size, flags); | |
0eeca283 | 66 | } |
f549d6c1 SS |
67 | } else if (!strncmp(kname, XATTR_SECURITY_PREFIX, |
68 | sizeof XATTR_SECURITY_PREFIX - 1)) { | |
69 | const char *suffix = kname + sizeof XATTR_SECURITY_PREFIX - 1; | |
70 | error = security_inode_setsecurity(d->d_inode, suffix, kvalue, | |
71 | size, flags); | |
72 | if (!error) | |
73 | fsnotify_xattr(d); | |
1da177e4 | 74 | } |
f549d6c1 SS |
75 | out: |
76 | up(&d->d_inode->i_sem); | |
1da177e4 LT |
77 | if (kvalue) |
78 | kfree(kvalue); | |
79 | return error; | |
80 | } | |
81 | ||
82 | asmlinkage long | |
83 | sys_setxattr(char __user *path, char __user *name, void __user *value, | |
84 | size_t size, int flags) | |
85 | { | |
86 | struct nameidata nd; | |
87 | int error; | |
88 | ||
89 | error = user_path_walk(path, &nd); | |
90 | if (error) | |
91 | return error; | |
92 | error = setxattr(nd.dentry, name, value, size, flags); | |
93 | path_release(&nd); | |
94 | return error; | |
95 | } | |
96 | ||
97 | asmlinkage long | |
98 | sys_lsetxattr(char __user *path, char __user *name, void __user *value, | |
99 | size_t size, int flags) | |
100 | { | |
101 | struct nameidata nd; | |
102 | int error; | |
103 | ||
104 | error = user_path_walk_link(path, &nd); | |
105 | if (error) | |
106 | return error; | |
107 | error = setxattr(nd.dentry, name, value, size, flags); | |
108 | path_release(&nd); | |
109 | return error; | |
110 | } | |
111 | ||
112 | asmlinkage long | |
113 | sys_fsetxattr(int fd, char __user *name, void __user *value, | |
114 | size_t size, int flags) | |
115 | { | |
116 | struct file *f; | |
117 | int error = -EBADF; | |
118 | ||
119 | f = fget(fd); | |
120 | if (!f) | |
121 | return error; | |
122 | error = setxattr(f->f_dentry, name, value, size, flags); | |
123 | fput(f); | |
124 | return error; | |
125 | } | |
126 | ||
127 | /* | |
128 | * Extended attribute GET operations | |
129 | */ | |
130 | static ssize_t | |
131 | getxattr(struct dentry *d, char __user *name, void __user *value, size_t size) | |
132 | { | |
133 | ssize_t error; | |
134 | void *kvalue = NULL; | |
135 | char kname[XATTR_NAME_MAX + 1]; | |
136 | ||
137 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
138 | if (error == 0 || error == sizeof(kname)) | |
139 | error = -ERANGE; | |
140 | if (error < 0) | |
141 | return error; | |
142 | ||
143 | if (size) { | |
144 | if (size > XATTR_SIZE_MAX) | |
145 | size = XATTR_SIZE_MAX; | |
d381d8a9 | 146 | kvalue = kzalloc(size, GFP_KERNEL); |
1da177e4 LT |
147 | if (!kvalue) |
148 | return -ENOMEM; | |
149 | } | |
150 | ||
f549d6c1 SS |
151 | error = security_inode_getxattr(d, kname); |
152 | if (error) | |
153 | goto out; | |
1da177e4 | 154 | error = -EOPNOTSUPP; |
f549d6c1 | 155 | if (d->d_inode->i_op && d->d_inode->i_op->getxattr) |
1da177e4 | 156 | error = d->d_inode->i_op->getxattr(d, kname, kvalue, size); |
d381d8a9 JM |
157 | |
158 | if (!strncmp(kname, XATTR_SECURITY_PREFIX, | |
159 | sizeof XATTR_SECURITY_PREFIX - 1)) { | |
f549d6c1 | 160 | const char *suffix = kname + sizeof XATTR_SECURITY_PREFIX - 1; |
d381d8a9 JM |
161 | int rv = security_inode_getsecurity(d->d_inode, suffix, kvalue, |
162 | size, error); | |
163 | /* Security module active: overwrite error value */ | |
164 | if (rv != -EOPNOTSUPP) | |
165 | error = rv; | |
f549d6c1 SS |
166 | } |
167 | if (error > 0) { | |
168 | if (size && copy_to_user(value, kvalue, error)) | |
169 | error = -EFAULT; | |
170 | } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { | |
171 | /* The file system tried to returned a value bigger | |
172 | than XATTR_SIZE_MAX bytes. Not possible. */ | |
173 | error = -E2BIG; | |
1da177e4 LT |
174 | } |
175 | out: | |
176 | if (kvalue) | |
177 | kfree(kvalue); | |
178 | return error; | |
179 | } | |
180 | ||
181 | asmlinkage ssize_t | |
182 | sys_getxattr(char __user *path, char __user *name, void __user *value, | |
183 | size_t size) | |
184 | { | |
185 | struct nameidata nd; | |
186 | ssize_t error; | |
187 | ||
188 | error = user_path_walk(path, &nd); | |
189 | if (error) | |
190 | return error; | |
191 | error = getxattr(nd.dentry, name, value, size); | |
192 | path_release(&nd); | |
193 | return error; | |
194 | } | |
195 | ||
196 | asmlinkage ssize_t | |
197 | sys_lgetxattr(char __user *path, char __user *name, void __user *value, | |
198 | size_t size) | |
199 | { | |
200 | struct nameidata nd; | |
201 | ssize_t error; | |
202 | ||
203 | error = user_path_walk_link(path, &nd); | |
204 | if (error) | |
205 | return error; | |
206 | error = getxattr(nd.dentry, name, value, size); | |
207 | path_release(&nd); | |
208 | return error; | |
209 | } | |
210 | ||
211 | asmlinkage ssize_t | |
212 | sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size) | |
213 | { | |
214 | struct file *f; | |
215 | ssize_t error = -EBADF; | |
216 | ||
217 | f = fget(fd); | |
218 | if (!f) | |
219 | return error; | |
220 | error = getxattr(f->f_dentry, name, value, size); | |
221 | fput(f); | |
222 | return error; | |
223 | } | |
224 | ||
225 | /* | |
226 | * Extended attribute LIST operations | |
227 | */ | |
228 | static ssize_t | |
229 | listxattr(struct dentry *d, char __user *list, size_t size) | |
230 | { | |
231 | ssize_t error; | |
232 | char *klist = NULL; | |
233 | ||
234 | if (size) { | |
235 | if (size > XATTR_LIST_MAX) | |
236 | size = XATTR_LIST_MAX; | |
237 | klist = kmalloc(size, GFP_KERNEL); | |
238 | if (!klist) | |
239 | return -ENOMEM; | |
240 | } | |
241 | ||
f549d6c1 SS |
242 | error = security_inode_listxattr(d); |
243 | if (error) | |
244 | goto out; | |
1da177e4 LT |
245 | error = -EOPNOTSUPP; |
246 | if (d->d_inode->i_op && d->d_inode->i_op->listxattr) { | |
1da177e4 | 247 | error = d->d_inode->i_op->listxattr(d, klist, size); |
f549d6c1 SS |
248 | } else { |
249 | error = security_inode_listsecurity(d->d_inode, klist, size); | |
250 | if (size && error >= size) | |
251 | error = -ERANGE; | |
252 | } | |
253 | if (error > 0) { | |
254 | if (size && copy_to_user(list, klist, error)) | |
255 | error = -EFAULT; | |
256 | } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { | |
257 | /* The file system tried to returned a list bigger | |
258 | than XATTR_LIST_MAX bytes. Not possible. */ | |
259 | error = -E2BIG; | |
1da177e4 LT |
260 | } |
261 | out: | |
262 | if (klist) | |
263 | kfree(klist); | |
264 | return error; | |
265 | } | |
266 | ||
267 | asmlinkage ssize_t | |
268 | sys_listxattr(char __user *path, char __user *list, size_t size) | |
269 | { | |
270 | struct nameidata nd; | |
271 | ssize_t error; | |
272 | ||
273 | error = user_path_walk(path, &nd); | |
274 | if (error) | |
275 | return error; | |
276 | error = listxattr(nd.dentry, list, size); | |
277 | path_release(&nd); | |
278 | return error; | |
279 | } | |
280 | ||
281 | asmlinkage ssize_t | |
282 | sys_llistxattr(char __user *path, char __user *list, size_t size) | |
283 | { | |
284 | struct nameidata nd; | |
285 | ssize_t error; | |
286 | ||
287 | error = user_path_walk_link(path, &nd); | |
288 | if (error) | |
289 | return error; | |
290 | error = listxattr(nd.dentry, list, size); | |
291 | path_release(&nd); | |
292 | return error; | |
293 | } | |
294 | ||
295 | asmlinkage ssize_t | |
296 | sys_flistxattr(int fd, char __user *list, size_t size) | |
297 | { | |
298 | struct file *f; | |
299 | ssize_t error = -EBADF; | |
300 | ||
301 | f = fget(fd); | |
302 | if (!f) | |
303 | return error; | |
304 | error = listxattr(f->f_dentry, list, size); | |
305 | fput(f); | |
306 | return error; | |
307 | } | |
308 | ||
309 | /* | |
310 | * Extended attribute REMOVE operations | |
311 | */ | |
312 | static long | |
313 | removexattr(struct dentry *d, char __user *name) | |
314 | { | |
315 | int error; | |
316 | char kname[XATTR_NAME_MAX + 1]; | |
317 | ||
318 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
319 | if (error == 0 || error == sizeof(kname)) | |
320 | error = -ERANGE; | |
321 | if (error < 0) | |
322 | return error; | |
323 | ||
324 | error = -EOPNOTSUPP; | |
325 | if (d->d_inode->i_op && d->d_inode->i_op->removexattr) { | |
326 | error = security_inode_removexattr(d, kname); | |
327 | if (error) | |
328 | goto out; | |
329 | down(&d->d_inode->i_sem); | |
330 | error = d->d_inode->i_op->removexattr(d, kname); | |
331 | up(&d->d_inode->i_sem); | |
b8006854 RL |
332 | if (!error) |
333 | fsnotify_xattr(d); | |
1da177e4 LT |
334 | } |
335 | out: | |
336 | return error; | |
337 | } | |
338 | ||
339 | asmlinkage long | |
340 | sys_removexattr(char __user *path, char __user *name) | |
341 | { | |
342 | struct nameidata nd; | |
343 | int error; | |
344 | ||
345 | error = user_path_walk(path, &nd); | |
346 | if (error) | |
347 | return error; | |
348 | error = removexattr(nd.dentry, name); | |
349 | path_release(&nd); | |
350 | return error; | |
351 | } | |
352 | ||
353 | asmlinkage long | |
354 | sys_lremovexattr(char __user *path, char __user *name) | |
355 | { | |
356 | struct nameidata nd; | |
357 | int error; | |
358 | ||
359 | error = user_path_walk_link(path, &nd); | |
360 | if (error) | |
361 | return error; | |
362 | error = removexattr(nd.dentry, name); | |
363 | path_release(&nd); | |
364 | return error; | |
365 | } | |
366 | ||
367 | asmlinkage long | |
368 | sys_fremovexattr(int fd, char __user *name) | |
369 | { | |
370 | struct file *f; | |
371 | int error = -EBADF; | |
372 | ||
373 | f = fget(fd); | |
374 | if (!f) | |
375 | return error; | |
376 | error = removexattr(f->f_dentry, name); | |
377 | fput(f); | |
378 | return error; | |
379 | } | |
380 | ||
381 | ||
382 | static const char * | |
383 | strcmp_prefix(const char *a, const char *a_prefix) | |
384 | { | |
385 | while (*a_prefix && *a == *a_prefix) { | |
386 | a++; | |
387 | a_prefix++; | |
388 | } | |
389 | return *a_prefix ? NULL : a; | |
390 | } | |
391 | ||
392 | /* | |
393 | * In order to implement different sets of xattr operations for each xattr | |
394 | * prefix with the generic xattr API, a filesystem should create a | |
395 | * null-terminated array of struct xattr_handler (one for each prefix) and | |
396 | * hang a pointer to it off of the s_xattr field of the superblock. | |
397 | * | |
398 | * The generic_fooxattr() functions will use this list to dispatch xattr | |
399 | * operations to the correct xattr_handler. | |
400 | */ | |
401 | #define for_each_xattr_handler(handlers, handler) \ | |
402 | for ((handler) = *(handlers)++; \ | |
403 | (handler) != NULL; \ | |
404 | (handler) = *(handlers)++) | |
405 | ||
406 | /* | |
407 | * Find the xattr_handler with the matching prefix. | |
408 | */ | |
409 | static struct xattr_handler * | |
410 | xattr_resolve_name(struct xattr_handler **handlers, const char **name) | |
411 | { | |
412 | struct xattr_handler *handler; | |
413 | ||
414 | if (!*name) | |
415 | return NULL; | |
416 | ||
417 | for_each_xattr_handler(handlers, handler) { | |
418 | const char *n = strcmp_prefix(*name, handler->prefix); | |
419 | if (n) { | |
420 | *name = n; | |
421 | break; | |
422 | } | |
423 | } | |
424 | return handler; | |
425 | } | |
426 | ||
427 | /* | |
428 | * Find the handler for the prefix and dispatch its get() operation. | |
429 | */ | |
430 | ssize_t | |
431 | generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) | |
432 | { | |
433 | struct xattr_handler *handler; | |
434 | struct inode *inode = dentry->d_inode; | |
435 | ||
436 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
437 | if (!handler) | |
438 | return -EOPNOTSUPP; | |
439 | return handler->get(inode, name, buffer, size); | |
440 | } | |
441 | ||
442 | /* | |
443 | * Combine the results of the list() operation from every xattr_handler in the | |
444 | * list. | |
445 | */ | |
446 | ssize_t | |
447 | generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) | |
448 | { | |
449 | struct inode *inode = dentry->d_inode; | |
450 | struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr; | |
451 | unsigned int size = 0; | |
452 | ||
453 | if (!buffer) { | |
454 | for_each_xattr_handler(handlers, handler) | |
455 | size += handler->list(inode, NULL, 0, NULL, 0); | |
456 | } else { | |
457 | char *buf = buffer; | |
458 | ||
459 | for_each_xattr_handler(handlers, handler) { | |
460 | size = handler->list(inode, buf, buffer_size, NULL, 0); | |
461 | if (size > buffer_size) | |
462 | return -ERANGE; | |
463 | buf += size; | |
464 | buffer_size -= size; | |
465 | } | |
466 | size = buf - buffer; | |
467 | } | |
468 | return size; | |
469 | } | |
470 | ||
471 | /* | |
472 | * Find the handler for the prefix and dispatch its set() operation. | |
473 | */ | |
474 | int | |
475 | generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) | |
476 | { | |
477 | struct xattr_handler *handler; | |
478 | struct inode *inode = dentry->d_inode; | |
479 | ||
480 | if (size == 0) | |
481 | value = ""; /* empty EA, do not remove */ | |
482 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
483 | if (!handler) | |
484 | return -EOPNOTSUPP; | |
485 | return handler->set(inode, name, value, size, flags); | |
486 | } | |
487 | ||
488 | /* | |
489 | * Find the handler for the prefix and dispatch its set() operation to remove | |
490 | * any associated extended attribute. | |
491 | */ | |
492 | int | |
493 | generic_removexattr(struct dentry *dentry, const char *name) | |
494 | { | |
495 | struct xattr_handler *handler; | |
496 | struct inode *inode = dentry->d_inode; | |
497 | ||
498 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
499 | if (!handler) | |
500 | return -EOPNOTSUPP; | |
501 | return handler->set(inode, name, NULL, 0, XATTR_REPLACE); | |
502 | } | |
503 | ||
504 | EXPORT_SYMBOL(generic_getxattr); | |
505 | EXPORT_SYMBOL(generic_listxattr); | |
506 | EXPORT_SYMBOL(generic_setxattr); | |
507 | EXPORT_SYMBOL(generic_removexattr); |