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> | |
19 | #include <asm/uaccess.h> | |
20 | ||
21 | /* | |
22 | * Extended attribute SET operations | |
23 | */ | |
24 | static long | |
25 | setxattr(struct dentry *d, char __user *name, void __user *value, | |
26 | size_t size, int flags) | |
27 | { | |
28 | int error; | |
29 | void *kvalue = NULL; | |
30 | char kname[XATTR_NAME_MAX + 1]; | |
31 | ||
32 | if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) | |
33 | return -EINVAL; | |
34 | ||
35 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
36 | if (error == 0 || error == sizeof(kname)) | |
37 | error = -ERANGE; | |
38 | if (error < 0) | |
39 | return error; | |
40 | ||
41 | if (size) { | |
42 | if (size > XATTR_SIZE_MAX) | |
43 | return -E2BIG; | |
44 | kvalue = kmalloc(size, GFP_KERNEL); | |
45 | if (!kvalue) | |
46 | return -ENOMEM; | |
47 | if (copy_from_user(kvalue, value, size)) { | |
48 | kfree(kvalue); | |
49 | return -EFAULT; | |
50 | } | |
51 | } | |
52 | ||
53 | error = -EOPNOTSUPP; | |
54 | if (d->d_inode->i_op && d->d_inode->i_op->setxattr) { | |
55 | down(&d->d_inode->i_sem); | |
56 | error = security_inode_setxattr(d, kname, kvalue, size, flags); | |
57 | if (error) | |
58 | goto out; | |
59 | error = d->d_inode->i_op->setxattr(d, kname, kvalue, size, flags); | |
60 | if (!error) | |
61 | security_inode_post_setxattr(d, kname, kvalue, size, flags); | |
62 | out: | |
63 | up(&d->d_inode->i_sem); | |
64 | } | |
65 | if (kvalue) | |
66 | kfree(kvalue); | |
67 | return error; | |
68 | } | |
69 | ||
70 | asmlinkage long | |
71 | sys_setxattr(char __user *path, char __user *name, void __user *value, | |
72 | size_t size, int flags) | |
73 | { | |
74 | struct nameidata nd; | |
75 | int error; | |
76 | ||
77 | error = user_path_walk(path, &nd); | |
78 | if (error) | |
79 | return error; | |
80 | error = setxattr(nd.dentry, name, value, size, flags); | |
81 | path_release(&nd); | |
82 | return error; | |
83 | } | |
84 | ||
85 | asmlinkage long | |
86 | sys_lsetxattr(char __user *path, char __user *name, void __user *value, | |
87 | size_t size, int flags) | |
88 | { | |
89 | struct nameidata nd; | |
90 | int error; | |
91 | ||
92 | error = user_path_walk_link(path, &nd); | |
93 | if (error) | |
94 | return error; | |
95 | error = setxattr(nd.dentry, name, value, size, flags); | |
96 | path_release(&nd); | |
97 | return error; | |
98 | } | |
99 | ||
100 | asmlinkage long | |
101 | sys_fsetxattr(int fd, char __user *name, void __user *value, | |
102 | size_t size, int flags) | |
103 | { | |
104 | struct file *f; | |
105 | int error = -EBADF; | |
106 | ||
107 | f = fget(fd); | |
108 | if (!f) | |
109 | return error; | |
110 | error = setxattr(f->f_dentry, name, value, size, flags); | |
111 | fput(f); | |
112 | return error; | |
113 | } | |
114 | ||
115 | /* | |
116 | * Extended attribute GET operations | |
117 | */ | |
118 | static ssize_t | |
119 | getxattr(struct dentry *d, char __user *name, void __user *value, size_t size) | |
120 | { | |
121 | ssize_t error; | |
122 | void *kvalue = NULL; | |
123 | char kname[XATTR_NAME_MAX + 1]; | |
124 | ||
125 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
126 | if (error == 0 || error == sizeof(kname)) | |
127 | error = -ERANGE; | |
128 | if (error < 0) | |
129 | return error; | |
130 | ||
131 | if (size) { | |
132 | if (size > XATTR_SIZE_MAX) | |
133 | size = XATTR_SIZE_MAX; | |
134 | kvalue = kmalloc(size, GFP_KERNEL); | |
135 | if (!kvalue) | |
136 | return -ENOMEM; | |
137 | } | |
138 | ||
139 | error = -EOPNOTSUPP; | |
140 | if (d->d_inode->i_op && d->d_inode->i_op->getxattr) { | |
141 | error = security_inode_getxattr(d, kname); | |
142 | if (error) | |
143 | goto out; | |
144 | error = d->d_inode->i_op->getxattr(d, kname, kvalue, size); | |
145 | if (error > 0) { | |
146 | if (size && copy_to_user(value, kvalue, error)) | |
147 | error = -EFAULT; | |
148 | } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { | |
149 | /* The file system tried to returned a value bigger | |
150 | than XATTR_SIZE_MAX bytes. Not possible. */ | |
151 | error = -E2BIG; | |
152 | } | |
153 | } | |
154 | out: | |
155 | if (kvalue) | |
156 | kfree(kvalue); | |
157 | return error; | |
158 | } | |
159 | ||
160 | asmlinkage ssize_t | |
161 | sys_getxattr(char __user *path, char __user *name, void __user *value, | |
162 | size_t size) | |
163 | { | |
164 | struct nameidata nd; | |
165 | ssize_t error; | |
166 | ||
167 | error = user_path_walk(path, &nd); | |
168 | if (error) | |
169 | return error; | |
170 | error = getxattr(nd.dentry, name, value, size); | |
171 | path_release(&nd); | |
172 | return error; | |
173 | } | |
174 | ||
175 | asmlinkage ssize_t | |
176 | sys_lgetxattr(char __user *path, char __user *name, void __user *value, | |
177 | size_t size) | |
178 | { | |
179 | struct nameidata nd; | |
180 | ssize_t error; | |
181 | ||
182 | error = user_path_walk_link(path, &nd); | |
183 | if (error) | |
184 | return error; | |
185 | error = getxattr(nd.dentry, name, value, size); | |
186 | path_release(&nd); | |
187 | return error; | |
188 | } | |
189 | ||
190 | asmlinkage ssize_t | |
191 | sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size) | |
192 | { | |
193 | struct file *f; | |
194 | ssize_t error = -EBADF; | |
195 | ||
196 | f = fget(fd); | |
197 | if (!f) | |
198 | return error; | |
199 | error = getxattr(f->f_dentry, name, value, size); | |
200 | fput(f); | |
201 | return error; | |
202 | } | |
203 | ||
204 | /* | |
205 | * Extended attribute LIST operations | |
206 | */ | |
207 | static ssize_t | |
208 | listxattr(struct dentry *d, char __user *list, size_t size) | |
209 | { | |
210 | ssize_t error; | |
211 | char *klist = NULL; | |
212 | ||
213 | if (size) { | |
214 | if (size > XATTR_LIST_MAX) | |
215 | size = XATTR_LIST_MAX; | |
216 | klist = kmalloc(size, GFP_KERNEL); | |
217 | if (!klist) | |
218 | return -ENOMEM; | |
219 | } | |
220 | ||
221 | error = -EOPNOTSUPP; | |
222 | if (d->d_inode->i_op && d->d_inode->i_op->listxattr) { | |
223 | error = security_inode_listxattr(d); | |
224 | if (error) | |
225 | goto out; | |
226 | error = d->d_inode->i_op->listxattr(d, klist, size); | |
227 | if (error > 0) { | |
228 | if (size && copy_to_user(list, klist, error)) | |
229 | error = -EFAULT; | |
230 | } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { | |
231 | /* The file system tried to returned a list bigger | |
232 | than XATTR_LIST_MAX bytes. Not possible. */ | |
233 | error = -E2BIG; | |
234 | } | |
235 | } | |
236 | out: | |
237 | if (klist) | |
238 | kfree(klist); | |
239 | return error; | |
240 | } | |
241 | ||
242 | asmlinkage ssize_t | |
243 | sys_listxattr(char __user *path, char __user *list, size_t size) | |
244 | { | |
245 | struct nameidata nd; | |
246 | ssize_t error; | |
247 | ||
248 | error = user_path_walk(path, &nd); | |
249 | if (error) | |
250 | return error; | |
251 | error = listxattr(nd.dentry, list, size); | |
252 | path_release(&nd); | |
253 | return error; | |
254 | } | |
255 | ||
256 | asmlinkage ssize_t | |
257 | sys_llistxattr(char __user *path, char __user *list, size_t size) | |
258 | { | |
259 | struct nameidata nd; | |
260 | ssize_t error; | |
261 | ||
262 | error = user_path_walk_link(path, &nd); | |
263 | if (error) | |
264 | return error; | |
265 | error = listxattr(nd.dentry, list, size); | |
266 | path_release(&nd); | |
267 | return error; | |
268 | } | |
269 | ||
270 | asmlinkage ssize_t | |
271 | sys_flistxattr(int fd, char __user *list, size_t size) | |
272 | { | |
273 | struct file *f; | |
274 | ssize_t error = -EBADF; | |
275 | ||
276 | f = fget(fd); | |
277 | if (!f) | |
278 | return error; | |
279 | error = listxattr(f->f_dentry, list, size); | |
280 | fput(f); | |
281 | return error; | |
282 | } | |
283 | ||
284 | /* | |
285 | * Extended attribute REMOVE operations | |
286 | */ | |
287 | static long | |
288 | removexattr(struct dentry *d, char __user *name) | |
289 | { | |
290 | int error; | |
291 | char kname[XATTR_NAME_MAX + 1]; | |
292 | ||
293 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
294 | if (error == 0 || error == sizeof(kname)) | |
295 | error = -ERANGE; | |
296 | if (error < 0) | |
297 | return error; | |
298 | ||
299 | error = -EOPNOTSUPP; | |
300 | if (d->d_inode->i_op && d->d_inode->i_op->removexattr) { | |
301 | error = security_inode_removexattr(d, kname); | |
302 | if (error) | |
303 | goto out; | |
304 | down(&d->d_inode->i_sem); | |
305 | error = d->d_inode->i_op->removexattr(d, kname); | |
306 | up(&d->d_inode->i_sem); | |
307 | } | |
308 | out: | |
309 | return error; | |
310 | } | |
311 | ||
312 | asmlinkage long | |
313 | sys_removexattr(char __user *path, char __user *name) | |
314 | { | |
315 | struct nameidata nd; | |
316 | int error; | |
317 | ||
318 | error = user_path_walk(path, &nd); | |
319 | if (error) | |
320 | return error; | |
321 | error = removexattr(nd.dentry, name); | |
322 | path_release(&nd); | |
323 | return error; | |
324 | } | |
325 | ||
326 | asmlinkage long | |
327 | sys_lremovexattr(char __user *path, char __user *name) | |
328 | { | |
329 | struct nameidata nd; | |
330 | int error; | |
331 | ||
332 | error = user_path_walk_link(path, &nd); | |
333 | if (error) | |
334 | return error; | |
335 | error = removexattr(nd.dentry, name); | |
336 | path_release(&nd); | |
337 | return error; | |
338 | } | |
339 | ||
340 | asmlinkage long | |
341 | sys_fremovexattr(int fd, char __user *name) | |
342 | { | |
343 | struct file *f; | |
344 | int error = -EBADF; | |
345 | ||
346 | f = fget(fd); | |
347 | if (!f) | |
348 | return error; | |
349 | error = removexattr(f->f_dentry, name); | |
350 | fput(f); | |
351 | return error; | |
352 | } | |
353 | ||
354 | ||
355 | static const char * | |
356 | strcmp_prefix(const char *a, const char *a_prefix) | |
357 | { | |
358 | while (*a_prefix && *a == *a_prefix) { | |
359 | a++; | |
360 | a_prefix++; | |
361 | } | |
362 | return *a_prefix ? NULL : a; | |
363 | } | |
364 | ||
365 | /* | |
366 | * In order to implement different sets of xattr operations for each xattr | |
367 | * prefix with the generic xattr API, a filesystem should create a | |
368 | * null-terminated array of struct xattr_handler (one for each prefix) and | |
369 | * hang a pointer to it off of the s_xattr field of the superblock. | |
370 | * | |
371 | * The generic_fooxattr() functions will use this list to dispatch xattr | |
372 | * operations to the correct xattr_handler. | |
373 | */ | |
374 | #define for_each_xattr_handler(handlers, handler) \ | |
375 | for ((handler) = *(handlers)++; \ | |
376 | (handler) != NULL; \ | |
377 | (handler) = *(handlers)++) | |
378 | ||
379 | /* | |
380 | * Find the xattr_handler with the matching prefix. | |
381 | */ | |
382 | static struct xattr_handler * | |
383 | xattr_resolve_name(struct xattr_handler **handlers, const char **name) | |
384 | { | |
385 | struct xattr_handler *handler; | |
386 | ||
387 | if (!*name) | |
388 | return NULL; | |
389 | ||
390 | for_each_xattr_handler(handlers, handler) { | |
391 | const char *n = strcmp_prefix(*name, handler->prefix); | |
392 | if (n) { | |
393 | *name = n; | |
394 | break; | |
395 | } | |
396 | } | |
397 | return handler; | |
398 | } | |
399 | ||
400 | /* | |
401 | * Find the handler for the prefix and dispatch its get() operation. | |
402 | */ | |
403 | ssize_t | |
404 | generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) | |
405 | { | |
406 | struct xattr_handler *handler; | |
407 | struct inode *inode = dentry->d_inode; | |
408 | ||
409 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
410 | if (!handler) | |
411 | return -EOPNOTSUPP; | |
412 | return handler->get(inode, name, buffer, size); | |
413 | } | |
414 | ||
415 | /* | |
416 | * Combine the results of the list() operation from every xattr_handler in the | |
417 | * list. | |
418 | */ | |
419 | ssize_t | |
420 | generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) | |
421 | { | |
422 | struct inode *inode = dentry->d_inode; | |
423 | struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr; | |
424 | unsigned int size = 0; | |
425 | ||
426 | if (!buffer) { | |
427 | for_each_xattr_handler(handlers, handler) | |
428 | size += handler->list(inode, NULL, 0, NULL, 0); | |
429 | } else { | |
430 | char *buf = buffer; | |
431 | ||
432 | for_each_xattr_handler(handlers, handler) { | |
433 | size = handler->list(inode, buf, buffer_size, NULL, 0); | |
434 | if (size > buffer_size) | |
435 | return -ERANGE; | |
436 | buf += size; | |
437 | buffer_size -= size; | |
438 | } | |
439 | size = buf - buffer; | |
440 | } | |
441 | return size; | |
442 | } | |
443 | ||
444 | /* | |
445 | * Find the handler for the prefix and dispatch its set() operation. | |
446 | */ | |
447 | int | |
448 | generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) | |
449 | { | |
450 | struct xattr_handler *handler; | |
451 | struct inode *inode = dentry->d_inode; | |
452 | ||
453 | if (size == 0) | |
454 | value = ""; /* empty EA, do not remove */ | |
455 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
456 | if (!handler) | |
457 | return -EOPNOTSUPP; | |
458 | return handler->set(inode, name, value, size, flags); | |
459 | } | |
460 | ||
461 | /* | |
462 | * Find the handler for the prefix and dispatch its set() operation to remove | |
463 | * any associated extended attribute. | |
464 | */ | |
465 | int | |
466 | generic_removexattr(struct dentry *dentry, const char *name) | |
467 | { | |
468 | struct xattr_handler *handler; | |
469 | struct inode *inode = dentry->d_inode; | |
470 | ||
471 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
472 | if (!handler) | |
473 | return -EOPNOTSUPP; | |
474 | return handler->set(inode, name, NULL, 0, XATTR_REPLACE); | |
475 | } | |
476 | ||
477 | EXPORT_SYMBOL(generic_getxattr); | |
478 | EXPORT_SYMBOL(generic_listxattr); | |
479 | EXPORT_SYMBOL(generic_setxattr); | |
480 | EXPORT_SYMBOL(generic_removexattr); |