Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/xattr.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 10582 byte(s)
Tag kernel26-2.6.12-alx-r9
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); |