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); | |
f99d49ad | 77 | kfree(kvalue); |
1da177e4 LT |
78 | return error; |
79 | } | |
80 | ||
81 | asmlinkage long | |
82 | sys_setxattr(char __user *path, char __user *name, void __user *value, | |
83 | size_t size, int flags) | |
84 | { | |
85 | struct nameidata nd; | |
86 | int error; | |
87 | ||
88 | error = user_path_walk(path, &nd); | |
89 | if (error) | |
90 | return error; | |
91 | error = setxattr(nd.dentry, name, value, size, flags); | |
92 | path_release(&nd); | |
93 | return error; | |
94 | } | |
95 | ||
96 | asmlinkage long | |
97 | sys_lsetxattr(char __user *path, char __user *name, void __user *value, | |
98 | size_t size, int flags) | |
99 | { | |
100 | struct nameidata nd; | |
101 | int error; | |
102 | ||
103 | error = user_path_walk_link(path, &nd); | |
104 | if (error) | |
105 | return error; | |
106 | error = setxattr(nd.dentry, name, value, size, flags); | |
107 | path_release(&nd); | |
108 | return error; | |
109 | } | |
110 | ||
111 | asmlinkage long | |
112 | sys_fsetxattr(int fd, char __user *name, void __user *value, | |
113 | size_t size, int flags) | |
114 | { | |
115 | struct file *f; | |
116 | int error = -EBADF; | |
117 | ||
118 | f = fget(fd); | |
119 | if (!f) | |
120 | return error; | |
121 | error = setxattr(f->f_dentry, name, value, size, flags); | |
122 | fput(f); | |
123 | return error; | |
124 | } | |
125 | ||
126 | /* | |
127 | * Extended attribute GET operations | |
128 | */ | |
129 | static ssize_t | |
130 | getxattr(struct dentry *d, char __user *name, void __user *value, size_t size) | |
131 | { | |
132 | ssize_t error; | |
133 | void *kvalue = NULL; | |
134 | char kname[XATTR_NAME_MAX + 1]; | |
135 | ||
136 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
137 | if (error == 0 || error == sizeof(kname)) | |
138 | error = -ERANGE; | |
139 | if (error < 0) | |
140 | return error; | |
141 | ||
142 | if (size) { | |
143 | if (size > XATTR_SIZE_MAX) | |
144 | size = XATTR_SIZE_MAX; | |
d381d8a9 | 145 | kvalue = kzalloc(size, GFP_KERNEL); |
1da177e4 LT |
146 | if (!kvalue) |
147 | return -ENOMEM; | |
148 | } | |
149 | ||
f549d6c1 SS |
150 | error = security_inode_getxattr(d, kname); |
151 | if (error) | |
152 | goto out; | |
1da177e4 | 153 | error = -EOPNOTSUPP; |
f549d6c1 | 154 | if (d->d_inode->i_op && d->d_inode->i_op->getxattr) |
1da177e4 | 155 | error = d->d_inode->i_op->getxattr(d, kname, kvalue, size); |
d381d8a9 JM |
156 | |
157 | if (!strncmp(kname, XATTR_SECURITY_PREFIX, | |
158 | sizeof XATTR_SECURITY_PREFIX - 1)) { | |
f549d6c1 | 159 | const char *suffix = kname + sizeof XATTR_SECURITY_PREFIX - 1; |
d381d8a9 JM |
160 | int rv = security_inode_getsecurity(d->d_inode, suffix, kvalue, |
161 | size, error); | |
162 | /* Security module active: overwrite error value */ | |
163 | if (rv != -EOPNOTSUPP) | |
164 | error = rv; | |
f549d6c1 SS |
165 | } |
166 | if (error > 0) { | |
167 | if (size && copy_to_user(value, kvalue, error)) | |
168 | error = -EFAULT; | |
169 | } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { | |
170 | /* The file system tried to returned a value bigger | |
171 | than XATTR_SIZE_MAX bytes. Not possible. */ | |
172 | error = -E2BIG; | |
1da177e4 LT |
173 | } |
174 | out: | |
f99d49ad | 175 | kfree(kvalue); |
1da177e4 LT |
176 | return error; |
177 | } | |
178 | ||
179 | asmlinkage ssize_t | |
180 | sys_getxattr(char __user *path, char __user *name, void __user *value, | |
181 | size_t size) | |
182 | { | |
183 | struct nameidata nd; | |
184 | ssize_t error; | |
185 | ||
186 | error = user_path_walk(path, &nd); | |
187 | if (error) | |
188 | return error; | |
189 | error = getxattr(nd.dentry, name, value, size); | |
190 | path_release(&nd); | |
191 | return error; | |
192 | } | |
193 | ||
194 | asmlinkage ssize_t | |
195 | sys_lgetxattr(char __user *path, char __user *name, void __user *value, | |
196 | size_t size) | |
197 | { | |
198 | struct nameidata nd; | |
199 | ssize_t error; | |
200 | ||
201 | error = user_path_walk_link(path, &nd); | |
202 | if (error) | |
203 | return error; | |
204 | error = getxattr(nd.dentry, name, value, size); | |
205 | path_release(&nd); | |
206 | return error; | |
207 | } | |
208 | ||
209 | asmlinkage ssize_t | |
210 | sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size) | |
211 | { | |
212 | struct file *f; | |
213 | ssize_t error = -EBADF; | |
214 | ||
215 | f = fget(fd); | |
216 | if (!f) | |
217 | return error; | |
218 | error = getxattr(f->f_dentry, name, value, size); | |
219 | fput(f); | |
220 | return error; | |
221 | } | |
222 | ||
223 | /* | |
224 | * Extended attribute LIST operations | |
225 | */ | |
226 | static ssize_t | |
227 | listxattr(struct dentry *d, char __user *list, size_t size) | |
228 | { | |
229 | ssize_t error; | |
230 | char *klist = NULL; | |
231 | ||
232 | if (size) { | |
233 | if (size > XATTR_LIST_MAX) | |
234 | size = XATTR_LIST_MAX; | |
235 | klist = kmalloc(size, GFP_KERNEL); | |
236 | if (!klist) | |
237 | return -ENOMEM; | |
238 | } | |
239 | ||
f549d6c1 SS |
240 | error = security_inode_listxattr(d); |
241 | if (error) | |
242 | goto out; | |
1da177e4 LT |
243 | error = -EOPNOTSUPP; |
244 | if (d->d_inode->i_op && d->d_inode->i_op->listxattr) { | |
1da177e4 | 245 | error = d->d_inode->i_op->listxattr(d, klist, size); |
f549d6c1 SS |
246 | } else { |
247 | error = security_inode_listsecurity(d->d_inode, klist, size); | |
248 | if (size && error >= size) | |
249 | error = -ERANGE; | |
250 | } | |
251 | if (error > 0) { | |
252 | if (size && copy_to_user(list, klist, error)) | |
253 | error = -EFAULT; | |
254 | } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { | |
255 | /* The file system tried to returned a list bigger | |
256 | than XATTR_LIST_MAX bytes. Not possible. */ | |
257 | error = -E2BIG; | |
1da177e4 LT |
258 | } |
259 | out: | |
f99d49ad | 260 | kfree(klist); |
1da177e4 LT |
261 | return error; |
262 | } | |
263 | ||
264 | asmlinkage ssize_t | |
265 | sys_listxattr(char __user *path, char __user *list, size_t size) | |
266 | { | |
267 | struct nameidata nd; | |
268 | ssize_t error; | |
269 | ||
270 | error = user_path_walk(path, &nd); | |
271 | if (error) | |
272 | return error; | |
273 | error = listxattr(nd.dentry, list, size); | |
274 | path_release(&nd); | |
275 | return error; | |
276 | } | |
277 | ||
278 | asmlinkage ssize_t | |
279 | sys_llistxattr(char __user *path, char __user *list, size_t size) | |
280 | { | |
281 | struct nameidata nd; | |
282 | ssize_t error; | |
283 | ||
284 | error = user_path_walk_link(path, &nd); | |
285 | if (error) | |
286 | return error; | |
287 | error = listxattr(nd.dentry, list, size); | |
288 | path_release(&nd); | |
289 | return error; | |
290 | } | |
291 | ||
292 | asmlinkage ssize_t | |
293 | sys_flistxattr(int fd, char __user *list, size_t size) | |
294 | { | |
295 | struct file *f; | |
296 | ssize_t error = -EBADF; | |
297 | ||
298 | f = fget(fd); | |
299 | if (!f) | |
300 | return error; | |
301 | error = listxattr(f->f_dentry, list, size); | |
302 | fput(f); | |
303 | return error; | |
304 | } | |
305 | ||
306 | /* | |
307 | * Extended attribute REMOVE operations | |
308 | */ | |
309 | static long | |
310 | removexattr(struct dentry *d, char __user *name) | |
311 | { | |
312 | int error; | |
313 | char kname[XATTR_NAME_MAX + 1]; | |
314 | ||
315 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
316 | if (error == 0 || error == sizeof(kname)) | |
317 | error = -ERANGE; | |
318 | if (error < 0) | |
319 | return error; | |
320 | ||
321 | error = -EOPNOTSUPP; | |
322 | if (d->d_inode->i_op && d->d_inode->i_op->removexattr) { | |
323 | error = security_inode_removexattr(d, kname); | |
324 | if (error) | |
325 | goto out; | |
326 | down(&d->d_inode->i_sem); | |
327 | error = d->d_inode->i_op->removexattr(d, kname); | |
328 | up(&d->d_inode->i_sem); | |
b8006854 RL |
329 | if (!error) |
330 | fsnotify_xattr(d); | |
1da177e4 LT |
331 | } |
332 | out: | |
333 | return error; | |
334 | } | |
335 | ||
336 | asmlinkage long | |
337 | sys_removexattr(char __user *path, char __user *name) | |
338 | { | |
339 | struct nameidata nd; | |
340 | int error; | |
341 | ||
342 | error = user_path_walk(path, &nd); | |
343 | if (error) | |
344 | return error; | |
345 | error = removexattr(nd.dentry, name); | |
346 | path_release(&nd); | |
347 | return error; | |
348 | } | |
349 | ||
350 | asmlinkage long | |
351 | sys_lremovexattr(char __user *path, char __user *name) | |
352 | { | |
353 | struct nameidata nd; | |
354 | int error; | |
355 | ||
356 | error = user_path_walk_link(path, &nd); | |
357 | if (error) | |
358 | return error; | |
359 | error = removexattr(nd.dentry, name); | |
360 | path_release(&nd); | |
361 | return error; | |
362 | } | |
363 | ||
364 | asmlinkage long | |
365 | sys_fremovexattr(int fd, char __user *name) | |
366 | { | |
367 | struct file *f; | |
368 | int error = -EBADF; | |
369 | ||
370 | f = fget(fd); | |
371 | if (!f) | |
372 | return error; | |
373 | error = removexattr(f->f_dentry, name); | |
374 | fput(f); | |
375 | return error; | |
376 | } | |
377 | ||
378 | ||
379 | static const char * | |
380 | strcmp_prefix(const char *a, const char *a_prefix) | |
381 | { | |
382 | while (*a_prefix && *a == *a_prefix) { | |
383 | a++; | |
384 | a_prefix++; | |
385 | } | |
386 | return *a_prefix ? NULL : a; | |
387 | } | |
388 | ||
389 | /* | |
390 | * In order to implement different sets of xattr operations for each xattr | |
391 | * prefix with the generic xattr API, a filesystem should create a | |
392 | * null-terminated array of struct xattr_handler (one for each prefix) and | |
393 | * hang a pointer to it off of the s_xattr field of the superblock. | |
394 | * | |
395 | * The generic_fooxattr() functions will use this list to dispatch xattr | |
396 | * operations to the correct xattr_handler. | |
397 | */ | |
398 | #define for_each_xattr_handler(handlers, handler) \ | |
399 | for ((handler) = *(handlers)++; \ | |
400 | (handler) != NULL; \ | |
401 | (handler) = *(handlers)++) | |
402 | ||
403 | /* | |
404 | * Find the xattr_handler with the matching prefix. | |
405 | */ | |
406 | static struct xattr_handler * | |
407 | xattr_resolve_name(struct xattr_handler **handlers, const char **name) | |
408 | { | |
409 | struct xattr_handler *handler; | |
410 | ||
411 | if (!*name) | |
412 | return NULL; | |
413 | ||
414 | for_each_xattr_handler(handlers, handler) { | |
415 | const char *n = strcmp_prefix(*name, handler->prefix); | |
416 | if (n) { | |
417 | *name = n; | |
418 | break; | |
419 | } | |
420 | } | |
421 | return handler; | |
422 | } | |
423 | ||
424 | /* | |
425 | * Find the handler for the prefix and dispatch its get() operation. | |
426 | */ | |
427 | ssize_t | |
428 | generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) | |
429 | { | |
430 | struct xattr_handler *handler; | |
431 | struct inode *inode = dentry->d_inode; | |
432 | ||
433 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
434 | if (!handler) | |
435 | return -EOPNOTSUPP; | |
436 | return handler->get(inode, name, buffer, size); | |
437 | } | |
438 | ||
439 | /* | |
440 | * Combine the results of the list() operation from every xattr_handler in the | |
441 | * list. | |
442 | */ | |
443 | ssize_t | |
444 | generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) | |
445 | { | |
446 | struct inode *inode = dentry->d_inode; | |
447 | struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr; | |
448 | unsigned int size = 0; | |
449 | ||
450 | if (!buffer) { | |
451 | for_each_xattr_handler(handlers, handler) | |
452 | size += handler->list(inode, NULL, 0, NULL, 0); | |
453 | } else { | |
454 | char *buf = buffer; | |
455 | ||
456 | for_each_xattr_handler(handlers, handler) { | |
457 | size = handler->list(inode, buf, buffer_size, NULL, 0); | |
458 | if (size > buffer_size) | |
459 | return -ERANGE; | |
460 | buf += size; | |
461 | buffer_size -= size; | |
462 | } | |
463 | size = buf - buffer; | |
464 | } | |
465 | return size; | |
466 | } | |
467 | ||
468 | /* | |
469 | * Find the handler for the prefix and dispatch its set() operation. | |
470 | */ | |
471 | int | |
472 | generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) | |
473 | { | |
474 | struct xattr_handler *handler; | |
475 | struct inode *inode = dentry->d_inode; | |
476 | ||
477 | if (size == 0) | |
478 | value = ""; /* empty EA, do not remove */ | |
479 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
480 | if (!handler) | |
481 | return -EOPNOTSUPP; | |
482 | return handler->set(inode, name, value, size, flags); | |
483 | } | |
484 | ||
485 | /* | |
486 | * Find the handler for the prefix and dispatch its set() operation to remove | |
487 | * any associated extended attribute. | |
488 | */ | |
489 | int | |
490 | generic_removexattr(struct dentry *dentry, const char *name) | |
491 | { | |
492 | struct xattr_handler *handler; | |
493 | struct inode *inode = dentry->d_inode; | |
494 | ||
495 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); | |
496 | if (!handler) | |
497 | return -EOPNOTSUPP; | |
498 | return handler->set(inode, name, NULL, 0, XATTR_REPLACE); | |
499 | } | |
500 | ||
501 | EXPORT_SYMBOL(generic_getxattr); | |
502 | EXPORT_SYMBOL(generic_listxattr); | |
503 | EXPORT_SYMBOL(generic_setxattr); | |
504 | EXPORT_SYMBOL(generic_removexattr); |