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Source at commit cdde9cf73945d547acd3e96f9508c79e84ad0bf1 created 12 years 9 months ago. By Maarten ter Huurne, MMC: JZ4740: Added support for CPU frequency changing | |
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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/file.h> |
13 | #include <linux/xattr.h> |
14 | #include <linux/mount.h> |
15 | #include <linux/namei.h> |
16 | #include <linux/security.h> |
17 | #include <linux/evm.h> |
18 | #include <linux/syscalls.h> |
19 | #include <linux/export.h> |
20 | #include <linux/fsnotify.h> |
21 | #include <linux/audit.h> |
22 | #include <linux/vmalloc.h> |
23 | |
24 | #include <asm/uaccess.h> |
25 | |
26 | /* |
27 | * Check permissions for extended attribute access. This is a bit complicated |
28 | * because different namespaces have very different rules. |
29 | */ |
30 | static int |
31 | xattr_permission(struct inode *inode, const char *name, int mask) |
32 | { |
33 | /* |
34 | * We can never set or remove an extended attribute on a read-only |
35 | * filesystem or on an immutable / append-only inode. |
36 | */ |
37 | if (mask & MAY_WRITE) { |
38 | if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) |
39 | return -EPERM; |
40 | } |
41 | |
42 | /* |
43 | * No restriction for security.* and system.* from the VFS. Decision |
44 | * on these is left to the underlying filesystem / security module. |
45 | */ |
46 | if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) || |
47 | !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
48 | return 0; |
49 | |
50 | /* |
51 | * The trusted.* namespace can only be accessed by privileged users. |
52 | */ |
53 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) { |
54 | if (!capable(CAP_SYS_ADMIN)) |
55 | return (mask & MAY_WRITE) ? -EPERM : -ENODATA; |
56 | return 0; |
57 | } |
58 | |
59 | /* |
60 | * In the user.* namespace, only regular files and directories can have |
61 | * extended attributes. For sticky directories, only the owner and |
62 | * privileged users can write attributes. |
63 | */ |
64 | if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) { |
65 | if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) |
66 | return (mask & MAY_WRITE) ? -EPERM : -ENODATA; |
67 | if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) && |
68 | (mask & MAY_WRITE) && !inode_owner_or_capable(inode)) |
69 | return -EPERM; |
70 | } |
71 | |
72 | return inode_permission(inode, mask); |
73 | } |
74 | |
75 | /** |
76 | * __vfs_setxattr_noperm - perform setxattr operation without performing |
77 | * permission checks. |
78 | * |
79 | * @dentry - object to perform setxattr on |
80 | * @name - xattr name to set |
81 | * @value - value to set @name to |
82 | * @size - size of @value |
83 | * @flags - flags to pass into filesystem operations |
84 | * |
85 | * returns the result of the internal setxattr or setsecurity operations. |
86 | * |
87 | * This function requires the caller to lock the inode's i_mutex before it |
88 | * is executed. It also assumes that the caller will make the appropriate |
89 | * permission checks. |
90 | */ |
91 | int __vfs_setxattr_noperm(struct dentry *dentry, const char *name, |
92 | const void *value, size_t size, int flags) |
93 | { |
94 | struct inode *inode = dentry->d_inode; |
95 | int error = -EOPNOTSUPP; |
96 | int issec = !strncmp(name, XATTR_SECURITY_PREFIX, |
97 | XATTR_SECURITY_PREFIX_LEN); |
98 | |
99 | if (issec) |
100 | inode->i_flags &= ~S_NOSEC; |
101 | if (inode->i_op->setxattr) { |
102 | error = inode->i_op->setxattr(dentry, name, value, size, flags); |
103 | if (!error) { |
104 | fsnotify_xattr(dentry); |
105 | security_inode_post_setxattr(dentry, name, value, |
106 | size, flags); |
107 | } |
108 | } else if (issec) { |
109 | const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; |
110 | error = security_inode_setsecurity(inode, suffix, value, |
111 | size, flags); |
112 | if (!error) |
113 | fsnotify_xattr(dentry); |
114 | } |
115 | |
116 | return error; |
117 | } |
118 | |
119 | |
120 | int |
121 | vfs_setxattr(struct dentry *dentry, const char *name, const void *value, |
122 | size_t size, int flags) |
123 | { |
124 | struct inode *inode = dentry->d_inode; |
125 | int error; |
126 | |
127 | error = xattr_permission(inode, name, MAY_WRITE); |
128 | if (error) |
129 | return error; |
130 | |
131 | mutex_lock(&inode->i_mutex); |
132 | error = security_inode_setxattr(dentry, name, value, size, flags); |
133 | if (error) |
134 | goto out; |
135 | |
136 | error = __vfs_setxattr_noperm(dentry, name, value, size, flags); |
137 | |
138 | out: |
139 | mutex_unlock(&inode->i_mutex); |
140 | return error; |
141 | } |
142 | EXPORT_SYMBOL_GPL(vfs_setxattr); |
143 | |
144 | ssize_t |
145 | xattr_getsecurity(struct inode *inode, const char *name, void *value, |
146 | size_t size) |
147 | { |
148 | void *buffer = NULL; |
149 | ssize_t len; |
150 | |
151 | if (!value || !size) { |
152 | len = security_inode_getsecurity(inode, name, &buffer, false); |
153 | goto out_noalloc; |
154 | } |
155 | |
156 | len = security_inode_getsecurity(inode, name, &buffer, true); |
157 | if (len < 0) |
158 | return len; |
159 | if (size < len) { |
160 | len = -ERANGE; |
161 | goto out; |
162 | } |
163 | memcpy(value, buffer, len); |
164 | out: |
165 | security_release_secctx(buffer, len); |
166 | out_noalloc: |
167 | return len; |
168 | } |
169 | EXPORT_SYMBOL_GPL(xattr_getsecurity); |
170 | |
171 | /* |
172 | * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr |
173 | * |
174 | * Allocate memory, if not already allocated, or re-allocate correct size, |
175 | * before retrieving the extended attribute. |
176 | * |
177 | * Returns the result of alloc, if failed, or the getxattr operation. |
178 | */ |
179 | ssize_t |
180 | vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value, |
181 | size_t xattr_size, gfp_t flags) |
182 | { |
183 | struct inode *inode = dentry->d_inode; |
184 | char *value = *xattr_value; |
185 | int error; |
186 | |
187 | error = xattr_permission(inode, name, MAY_READ); |
188 | if (error) |
189 | return error; |
190 | |
191 | if (!inode->i_op->getxattr) |
192 | return -EOPNOTSUPP; |
193 | |
194 | error = inode->i_op->getxattr(dentry, name, NULL, 0); |
195 | if (error < 0) |
196 | return error; |
197 | |
198 | if (!value || (error > xattr_size)) { |
199 | value = krealloc(*xattr_value, error + 1, flags); |
200 | if (!value) |
201 | return -ENOMEM; |
202 | memset(value, 0, error + 1); |
203 | } |
204 | |
205 | error = inode->i_op->getxattr(dentry, name, value, error); |
206 | *xattr_value = value; |
207 | return error; |
208 | } |
209 | |
210 | /* Compare an extended attribute value with the given value */ |
211 | int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name, |
212 | const char *value, size_t size, gfp_t flags) |
213 | { |
214 | char *xattr_value = NULL; |
215 | int rc; |
216 | |
217 | rc = vfs_getxattr_alloc(dentry, xattr_name, &xattr_value, 0, flags); |
218 | if (rc < 0) |
219 | return rc; |
220 | |
221 | if ((rc != size) || (memcmp(xattr_value, value, rc) != 0)) |
222 | rc = -EINVAL; |
223 | else |
224 | rc = 0; |
225 | kfree(xattr_value); |
226 | return rc; |
227 | } |
228 | |
229 | ssize_t |
230 | vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size) |
231 | { |
232 | struct inode *inode = dentry->d_inode; |
233 | int error; |
234 | |
235 | error = xattr_permission(inode, name, MAY_READ); |
236 | if (error) |
237 | return error; |
238 | |
239 | error = security_inode_getxattr(dentry, name); |
240 | if (error) |
241 | return error; |
242 | |
243 | if (!strncmp(name, XATTR_SECURITY_PREFIX, |
244 | XATTR_SECURITY_PREFIX_LEN)) { |
245 | const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; |
246 | int ret = xattr_getsecurity(inode, suffix, value, size); |
247 | /* |
248 | * Only overwrite the return value if a security module |
249 | * is actually active. |
250 | */ |
251 | if (ret == -EOPNOTSUPP) |
252 | goto nolsm; |
253 | return ret; |
254 | } |
255 | nolsm: |
256 | if (inode->i_op->getxattr) |
257 | error = inode->i_op->getxattr(dentry, name, value, size); |
258 | else |
259 | error = -EOPNOTSUPP; |
260 | |
261 | return error; |
262 | } |
263 | EXPORT_SYMBOL_GPL(vfs_getxattr); |
264 | |
265 | ssize_t |
266 | vfs_listxattr(struct dentry *d, char *list, size_t size) |
267 | { |
268 | ssize_t error; |
269 | |
270 | error = security_inode_listxattr(d); |
271 | if (error) |
272 | return error; |
273 | error = -EOPNOTSUPP; |
274 | if (d->d_inode->i_op->listxattr) { |
275 | error = d->d_inode->i_op->listxattr(d, list, size); |
276 | } else { |
277 | error = security_inode_listsecurity(d->d_inode, list, size); |
278 | if (size && error > size) |
279 | error = -ERANGE; |
280 | } |
281 | return error; |
282 | } |
283 | EXPORT_SYMBOL_GPL(vfs_listxattr); |
284 | |
285 | int |
286 | vfs_removexattr(struct dentry *dentry, const char *name) |
287 | { |
288 | struct inode *inode = dentry->d_inode; |
289 | int error; |
290 | |
291 | if (!inode->i_op->removexattr) |
292 | return -EOPNOTSUPP; |
293 | |
294 | error = xattr_permission(inode, name, MAY_WRITE); |
295 | if (error) |
296 | return error; |
297 | |
298 | error = security_inode_removexattr(dentry, name); |
299 | if (error) |
300 | return error; |
301 | |
302 | mutex_lock(&inode->i_mutex); |
303 | error = inode->i_op->removexattr(dentry, name); |
304 | mutex_unlock(&inode->i_mutex); |
305 | |
306 | if (!error) { |
307 | fsnotify_xattr(dentry); |
308 | evm_inode_post_removexattr(dentry, name); |
309 | } |
310 | return error; |
311 | } |
312 | EXPORT_SYMBOL_GPL(vfs_removexattr); |
313 | |
314 | |
315 | /* |
316 | * Extended attribute SET operations |
317 | */ |
318 | static long |
319 | setxattr(struct dentry *d, const char __user *name, const void __user *value, |
320 | size_t size, int flags) |
321 | { |
322 | int error; |
323 | void *kvalue = NULL; |
324 | void *vvalue = NULL; /* If non-NULL, we used vmalloc() */ |
325 | char kname[XATTR_NAME_MAX + 1]; |
326 | |
327 | if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) |
328 | return -EINVAL; |
329 | |
330 | error = strncpy_from_user(kname, name, sizeof(kname)); |
331 | if (error == 0 || error == sizeof(kname)) |
332 | error = -ERANGE; |
333 | if (error < 0) |
334 | return error; |
335 | |
336 | if (size) { |
337 | if (size > XATTR_SIZE_MAX) |
338 | return -E2BIG; |
339 | kvalue = kmalloc(size, GFP_KERNEL | __GFP_NOWARN); |
340 | if (!kvalue) { |
341 | vvalue = vmalloc(size); |
342 | if (!vvalue) |
343 | return -ENOMEM; |
344 | kvalue = vvalue; |
345 | } |
346 | if (copy_from_user(kvalue, value, size)) { |
347 | error = -EFAULT; |
348 | goto out; |
349 | } |
350 | } |
351 | |
352 | error = vfs_setxattr(d, kname, kvalue, size, flags); |
353 | out: |
354 | if (vvalue) |
355 | vfree(vvalue); |
356 | else |
357 | kfree(kvalue); |
358 | return error; |
359 | } |
360 | |
361 | SYSCALL_DEFINE5(setxattr, const char __user *, pathname, |
362 | const char __user *, name, const void __user *, value, |
363 | size_t, size, int, flags) |
364 | { |
365 | struct path path; |
366 | int error; |
367 | |
368 | error = user_path(pathname, &path); |
369 | if (error) |
370 | return error; |
371 | error = mnt_want_write(path.mnt); |
372 | if (!error) { |
373 | error = setxattr(path.dentry, name, value, size, flags); |
374 | mnt_drop_write(path.mnt); |
375 | } |
376 | path_put(&path); |
377 | return error; |
378 | } |
379 | |
380 | SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname, |
381 | const char __user *, name, const void __user *, value, |
382 | size_t, size, int, flags) |
383 | { |
384 | struct path path; |
385 | int error; |
386 | |
387 | error = user_lpath(pathname, &path); |
388 | if (error) |
389 | return error; |
390 | error = mnt_want_write(path.mnt); |
391 | if (!error) { |
392 | error = setxattr(path.dentry, name, value, size, flags); |
393 | mnt_drop_write(path.mnt); |
394 | } |
395 | path_put(&path); |
396 | return error; |
397 | } |
398 | |
399 | SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name, |
400 | const void __user *,value, size_t, size, int, flags) |
401 | { |
402 | int fput_needed; |
403 | struct file *f; |
404 | struct dentry *dentry; |
405 | int error = -EBADF; |
406 | |
407 | f = fget_light(fd, &fput_needed); |
408 | if (!f) |
409 | return error; |
410 | dentry = f->f_path.dentry; |
411 | audit_inode(NULL, dentry); |
412 | error = mnt_want_write_file(f); |
413 | if (!error) { |
414 | error = setxattr(dentry, name, value, size, flags); |
415 | mnt_drop_write_file(f); |
416 | } |
417 | fput_light(f, fput_needed); |
418 | return error; |
419 | } |
420 | |
421 | /* |
422 | * Extended attribute GET operations |
423 | */ |
424 | static ssize_t |
425 | getxattr(struct dentry *d, const char __user *name, void __user *value, |
426 | size_t size) |
427 | { |
428 | ssize_t error; |
429 | void *kvalue = NULL; |
430 | void *vvalue = NULL; |
431 | char kname[XATTR_NAME_MAX + 1]; |
432 | |
433 | error = strncpy_from_user(kname, name, sizeof(kname)); |
434 | if (error == 0 || error == sizeof(kname)) |
435 | error = -ERANGE; |
436 | if (error < 0) |
437 | return error; |
438 | |
439 | if (size) { |
440 | if (size > XATTR_SIZE_MAX) |
441 | size = XATTR_SIZE_MAX; |
442 | kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); |
443 | if (!kvalue) { |
444 | vvalue = vmalloc(size); |
445 | if (!vvalue) |
446 | return -ENOMEM; |
447 | kvalue = vvalue; |
448 | } |
449 | } |
450 | |
451 | error = vfs_getxattr(d, kname, kvalue, size); |
452 | if (error > 0) { |
453 | if (size && copy_to_user(value, kvalue, error)) |
454 | error = -EFAULT; |
455 | } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { |
456 | /* The file system tried to returned a value bigger |
457 | than XATTR_SIZE_MAX bytes. Not possible. */ |
458 | error = -E2BIG; |
459 | } |
460 | if (vvalue) |
461 | vfree(vvalue); |
462 | else |
463 | kfree(kvalue); |
464 | return error; |
465 | } |
466 | |
467 | SYSCALL_DEFINE4(getxattr, const char __user *, pathname, |
468 | const char __user *, name, void __user *, value, size_t, size) |
469 | { |
470 | struct path path; |
471 | ssize_t error; |
472 | |
473 | error = user_path(pathname, &path); |
474 | if (error) |
475 | return error; |
476 | error = getxattr(path.dentry, name, value, size); |
477 | path_put(&path); |
478 | return error; |
479 | } |
480 | |
481 | SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname, |
482 | const char __user *, name, void __user *, value, size_t, size) |
483 | { |
484 | struct path path; |
485 | ssize_t error; |
486 | |
487 | error = user_lpath(pathname, &path); |
488 | if (error) |
489 | return error; |
490 | error = getxattr(path.dentry, name, value, size); |
491 | path_put(&path); |
492 | return error; |
493 | } |
494 | |
495 | SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name, |
496 | void __user *, value, size_t, size) |
497 | { |
498 | int fput_needed; |
499 | struct file *f; |
500 | ssize_t error = -EBADF; |
501 | |
502 | f = fget_light(fd, &fput_needed); |
503 | if (!f) |
504 | return error; |
505 | audit_inode(NULL, f->f_path.dentry); |
506 | error = getxattr(f->f_path.dentry, name, value, size); |
507 | fput_light(f, fput_needed); |
508 | return error; |
509 | } |
510 | |
511 | /* |
512 | * Extended attribute LIST operations |
513 | */ |
514 | static ssize_t |
515 | listxattr(struct dentry *d, char __user *list, size_t size) |
516 | { |
517 | ssize_t error; |
518 | char *klist = NULL; |
519 | char *vlist = NULL; /* If non-NULL, we used vmalloc() */ |
520 | |
521 | if (size) { |
522 | if (size > XATTR_LIST_MAX) |
523 | size = XATTR_LIST_MAX; |
524 | klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL); |
525 | if (!klist) { |
526 | vlist = vmalloc(size); |
527 | if (!vlist) |
528 | return -ENOMEM; |
529 | klist = vlist; |
530 | } |
531 | } |
532 | |
533 | error = vfs_listxattr(d, klist, size); |
534 | if (error > 0) { |
535 | if (size && copy_to_user(list, klist, error)) |
536 | error = -EFAULT; |
537 | } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { |
538 | /* The file system tried to returned a list bigger |
539 | than XATTR_LIST_MAX bytes. Not possible. */ |
540 | error = -E2BIG; |
541 | } |
542 | if (vlist) |
543 | vfree(vlist); |
544 | else |
545 | kfree(klist); |
546 | return error; |
547 | } |
548 | |
549 | SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list, |
550 | size_t, size) |
551 | { |
552 | struct path path; |
553 | ssize_t error; |
554 | |
555 | error = user_path(pathname, &path); |
556 | if (error) |
557 | return error; |
558 | error = listxattr(path.dentry, list, size); |
559 | path_put(&path); |
560 | return error; |
561 | } |
562 | |
563 | SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list, |
564 | size_t, size) |
565 | { |
566 | struct path path; |
567 | ssize_t error; |
568 | |
569 | error = user_lpath(pathname, &path); |
570 | if (error) |
571 | return error; |
572 | error = listxattr(path.dentry, list, size); |
573 | path_put(&path); |
574 | return error; |
575 | } |
576 | |
577 | SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size) |
578 | { |
579 | int fput_needed; |
580 | struct file *f; |
581 | ssize_t error = -EBADF; |
582 | |
583 | f = fget_light(fd, &fput_needed); |
584 | if (!f) |
585 | return error; |
586 | audit_inode(NULL, f->f_path.dentry); |
587 | error = listxattr(f->f_path.dentry, list, size); |
588 | fput_light(f, fput_needed); |
589 | return error; |
590 | } |
591 | |
592 | /* |
593 | * Extended attribute REMOVE operations |
594 | */ |
595 | static long |
596 | removexattr(struct dentry *d, const char __user *name) |
597 | { |
598 | int error; |
599 | char kname[XATTR_NAME_MAX + 1]; |
600 | |
601 | error = strncpy_from_user(kname, name, sizeof(kname)); |
602 | if (error == 0 || error == sizeof(kname)) |
603 | error = -ERANGE; |
604 | if (error < 0) |
605 | return error; |
606 | |
607 | return vfs_removexattr(d, kname); |
608 | } |
609 | |
610 | SYSCALL_DEFINE2(removexattr, const char __user *, pathname, |
611 | const char __user *, name) |
612 | { |
613 | struct path path; |
614 | int error; |
615 | |
616 | error = user_path(pathname, &path); |
617 | if (error) |
618 | return error; |
619 | error = mnt_want_write(path.mnt); |
620 | if (!error) { |
621 | error = removexattr(path.dentry, name); |
622 | mnt_drop_write(path.mnt); |
623 | } |
624 | path_put(&path); |
625 | return error; |
626 | } |
627 | |
628 | SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname, |
629 | const char __user *, name) |
630 | { |
631 | struct path path; |
632 | int error; |
633 | |
634 | error = user_lpath(pathname, &path); |
635 | if (error) |
636 | return error; |
637 | error = mnt_want_write(path.mnt); |
638 | if (!error) { |
639 | error = removexattr(path.dentry, name); |
640 | mnt_drop_write(path.mnt); |
641 | } |
642 | path_put(&path); |
643 | return error; |
644 | } |
645 | |
646 | SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name) |
647 | { |
648 | int fput_needed; |
649 | struct file *f; |
650 | struct dentry *dentry; |
651 | int error = -EBADF; |
652 | |
653 | f = fget_light(fd, &fput_needed); |
654 | if (!f) |
655 | return error; |
656 | dentry = f->f_path.dentry; |
657 | audit_inode(NULL, dentry); |
658 | error = mnt_want_write_file(f); |
659 | if (!error) { |
660 | error = removexattr(dentry, name); |
661 | mnt_drop_write_file(f); |
662 | } |
663 | fput_light(f, fput_needed); |
664 | return error; |
665 | } |
666 | |
667 | |
668 | static const char * |
669 | strcmp_prefix(const char *a, const char *a_prefix) |
670 | { |
671 | while (*a_prefix && *a == *a_prefix) { |
672 | a++; |
673 | a_prefix++; |
674 | } |
675 | return *a_prefix ? NULL : a; |
676 | } |
677 | |
678 | /* |
679 | * In order to implement different sets of xattr operations for each xattr |
680 | * prefix with the generic xattr API, a filesystem should create a |
681 | * null-terminated array of struct xattr_handler (one for each prefix) and |
682 | * hang a pointer to it off of the s_xattr field of the superblock. |
683 | * |
684 | * The generic_fooxattr() functions will use this list to dispatch xattr |
685 | * operations to the correct xattr_handler. |
686 | */ |
687 | #define for_each_xattr_handler(handlers, handler) \ |
688 | for ((handler) = *(handlers)++; \ |
689 | (handler) != NULL; \ |
690 | (handler) = *(handlers)++) |
691 | |
692 | /* |
693 | * Find the xattr_handler with the matching prefix. |
694 | */ |
695 | static const struct xattr_handler * |
696 | xattr_resolve_name(const struct xattr_handler **handlers, const char **name) |
697 | { |
698 | const struct xattr_handler *handler; |
699 | |
700 | if (!*name) |
701 | return NULL; |
702 | |
703 | for_each_xattr_handler(handlers, handler) { |
704 | const char *n = strcmp_prefix(*name, handler->prefix); |
705 | if (n) { |
706 | *name = n; |
707 | break; |
708 | } |
709 | } |
710 | return handler; |
711 | } |
712 | |
713 | /* |
714 | * Find the handler for the prefix and dispatch its get() operation. |
715 | */ |
716 | ssize_t |
717 | generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) |
718 | { |
719 | const struct xattr_handler *handler; |
720 | |
721 | handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); |
722 | if (!handler) |
723 | return -EOPNOTSUPP; |
724 | return handler->get(dentry, name, buffer, size, handler->flags); |
725 | } |
726 | |
727 | /* |
728 | * Combine the results of the list() operation from every xattr_handler in the |
729 | * list. |
730 | */ |
731 | ssize_t |
732 | generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) |
733 | { |
734 | const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr; |
735 | unsigned int size = 0; |
736 | |
737 | if (!buffer) { |
738 | for_each_xattr_handler(handlers, handler) { |
739 | size += handler->list(dentry, NULL, 0, NULL, 0, |
740 | handler->flags); |
741 | } |
742 | } else { |
743 | char *buf = buffer; |
744 | |
745 | for_each_xattr_handler(handlers, handler) { |
746 | size = handler->list(dentry, buf, buffer_size, |
747 | NULL, 0, handler->flags); |
748 | if (size > buffer_size) |
749 | return -ERANGE; |
750 | buf += size; |
751 | buffer_size -= size; |
752 | } |
753 | size = buf - buffer; |
754 | } |
755 | return size; |
756 | } |
757 | |
758 | /* |
759 | * Find the handler for the prefix and dispatch its set() operation. |
760 | */ |
761 | int |
762 | generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) |
763 | { |
764 | const struct xattr_handler *handler; |
765 | |
766 | if (size == 0) |
767 | value = ""; /* empty EA, do not remove */ |
768 | handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); |
769 | if (!handler) |
770 | return -EOPNOTSUPP; |
771 | return handler->set(dentry, name, value, size, flags, handler->flags); |
772 | } |
773 | |
774 | /* |
775 | * Find the handler for the prefix and dispatch its set() operation to remove |
776 | * any associated extended attribute. |
777 | */ |
778 | int |
779 | generic_removexattr(struct dentry *dentry, const char *name) |
780 | { |
781 | const struct xattr_handler *handler; |
782 | |
783 | handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); |
784 | if (!handler) |
785 | return -EOPNOTSUPP; |
786 | return handler->set(dentry, name, NULL, 0, |
787 | XATTR_REPLACE, handler->flags); |
788 | } |
789 | |
790 | EXPORT_SYMBOL(generic_getxattr); |
791 | EXPORT_SYMBOL(generic_listxattr); |
792 | EXPORT_SYMBOL(generic_setxattr); |
793 | EXPORT_SYMBOL(generic_removexattr); |
794 |
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