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