1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | File: fs/xattr.c |
4 | |
5 | Extended attribute handling. |
6 | |
7 | Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org> |
8 | Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com> |
9 | Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> |
10 | */ |
11 | #include <linux/fs.h> |
12 | #include <linux/filelock.h> |
13 | #include <linux/slab.h> |
14 | #include <linux/file.h> |
15 | #include <linux/xattr.h> |
16 | #include <linux/mount.h> |
17 | #include <linux/namei.h> |
18 | #include <linux/security.h> |
19 | #include <linux/syscalls.h> |
20 | #include <linux/export.h> |
21 | #include <linux/fsnotify.h> |
22 | #include <linux/audit.h> |
23 | #include <linux/vmalloc.h> |
24 | #include <linux/posix_acl_xattr.h> |
25 | |
26 | #include <linux/uaccess.h> |
27 | |
28 | #include "internal.h" |
29 | |
30 | static const char * |
31 | strcmp_prefix(const char *a, const char *a_prefix) |
32 | { |
33 | while (*a_prefix && *a == *a_prefix) { |
34 | a++; |
35 | a_prefix++; |
36 | } |
37 | return *a_prefix ? NULL : a; |
38 | } |
39 | |
40 | /* |
41 | * In order to implement different sets of xattr operations for each xattr |
42 | * prefix, a filesystem should create a null-terminated array of struct |
43 | * xattr_handler (one for each prefix) and hang a pointer to it off of the |
44 | * s_xattr field of the superblock. |
45 | */ |
46 | #define for_each_xattr_handler(handlers, handler) \ |
47 | if (handlers) \ |
48 | for ((handler) = *(handlers)++; \ |
49 | (handler) != NULL; \ |
50 | (handler) = *(handlers)++) |
51 | |
52 | /* |
53 | * Find the xattr_handler with the matching prefix. |
54 | */ |
55 | static const struct xattr_handler * |
56 | xattr_resolve_name(struct inode *inode, const char **name) |
57 | { |
58 | const struct xattr_handler * const *handlers = inode->i_sb->s_xattr; |
59 | const struct xattr_handler *handler; |
60 | |
61 | if (!(inode->i_opflags & IOP_XATTR)) { |
62 | if (unlikely(is_bad_inode(inode))) |
63 | return ERR_PTR(error: -EIO); |
64 | return ERR_PTR(error: -EOPNOTSUPP); |
65 | } |
66 | for_each_xattr_handler(handlers, handler) { |
67 | const char *n; |
68 | |
69 | n = strcmp_prefix(a: *name, a_prefix: xattr_prefix(handler)); |
70 | if (n) { |
71 | if (!handler->prefix ^ !*n) { |
72 | if (*n) |
73 | continue; |
74 | return ERR_PTR(error: -EINVAL); |
75 | } |
76 | *name = n; |
77 | return handler; |
78 | } |
79 | } |
80 | return ERR_PTR(error: -EOPNOTSUPP); |
81 | } |
82 | |
83 | /** |
84 | * may_write_xattr - check whether inode allows writing xattr |
85 | * @idmap: idmap of the mount the inode was found from |
86 | * @inode: the inode on which to set an xattr |
87 | * |
88 | * Check whether the inode allows writing xattrs. Specifically, we can never |
89 | * set or remove an extended attribute on a read-only filesystem or on an |
90 | * immutable / append-only inode. |
91 | * |
92 | * We also need to ensure that the inode has a mapping in the mount to |
93 | * not risk writing back invalid i_{g,u}id values. |
94 | * |
95 | * Return: On success zero is returned. On error a negative errno is returned. |
96 | */ |
97 | int may_write_xattr(struct mnt_idmap *idmap, struct inode *inode) |
98 | { |
99 | if (IS_IMMUTABLE(inode)) |
100 | return -EPERM; |
101 | if (IS_APPEND(inode)) |
102 | return -EPERM; |
103 | if (HAS_UNMAPPED_ID(idmap, inode)) |
104 | return -EPERM; |
105 | return 0; |
106 | } |
107 | |
108 | /* |
109 | * Check permissions for extended attribute access. This is a bit complicated |
110 | * because different namespaces have very different rules. |
111 | */ |
112 | static int |
113 | xattr_permission(struct mnt_idmap *idmap, struct inode *inode, |
114 | const char *name, int mask) |
115 | { |
116 | if (mask & MAY_WRITE) { |
117 | int ret; |
118 | |
119 | ret = may_write_xattr(idmap, inode); |
120 | if (ret) |
121 | return ret; |
122 | } |
123 | |
124 | /* |
125 | * No restriction for security.* and system.* from the VFS. Decision |
126 | * on these is left to the underlying filesystem / security module. |
127 | */ |
128 | if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) || |
129 | !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
130 | return 0; |
131 | |
132 | /* |
133 | * The trusted.* namespace can only be accessed by privileged users. |
134 | */ |
135 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) { |
136 | if (!capable(CAP_SYS_ADMIN)) |
137 | return (mask & MAY_WRITE) ? -EPERM : -ENODATA; |
138 | return 0; |
139 | } |
140 | |
141 | /* |
142 | * In the user.* namespace, only regular files and directories can have |
143 | * extended attributes. For sticky directories, only the owner and |
144 | * privileged users can write attributes. |
145 | */ |
146 | if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) { |
147 | if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) |
148 | return (mask & MAY_WRITE) ? -EPERM : -ENODATA; |
149 | if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) && |
150 | (mask & MAY_WRITE) && |
151 | !inode_owner_or_capable(idmap, inode)) |
152 | return -EPERM; |
153 | } |
154 | |
155 | return inode_permission(idmap, inode, mask); |
156 | } |
157 | |
158 | /* |
159 | * Look for any handler that deals with the specified namespace. |
160 | */ |
161 | int |
162 | xattr_supports_user_prefix(struct inode *inode) |
163 | { |
164 | const struct xattr_handler * const *handlers = inode->i_sb->s_xattr; |
165 | const struct xattr_handler *handler; |
166 | |
167 | if (!(inode->i_opflags & IOP_XATTR)) { |
168 | if (unlikely(is_bad_inode(inode))) |
169 | return -EIO; |
170 | return -EOPNOTSUPP; |
171 | } |
172 | |
173 | for_each_xattr_handler(handlers, handler) { |
174 | if (!strncmp(xattr_prefix(handler), XATTR_USER_PREFIX, |
175 | XATTR_USER_PREFIX_LEN)) |
176 | return 0; |
177 | } |
178 | |
179 | return -EOPNOTSUPP; |
180 | } |
181 | EXPORT_SYMBOL(xattr_supports_user_prefix); |
182 | |
183 | int |
184 | __vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, |
185 | struct inode *inode, const char *name, const void *value, |
186 | size_t size, int flags) |
187 | { |
188 | const struct xattr_handler *handler; |
189 | |
190 | if (is_posix_acl_xattr(name)) |
191 | return -EOPNOTSUPP; |
192 | |
193 | handler = xattr_resolve_name(inode, name: &name); |
194 | if (IS_ERR(ptr: handler)) |
195 | return PTR_ERR(ptr: handler); |
196 | if (!handler->set) |
197 | return -EOPNOTSUPP; |
198 | if (size == 0) |
199 | value = "" ; /* empty EA, do not remove */ |
200 | return handler->set(handler, idmap, dentry, inode, name, value, |
201 | size, flags); |
202 | } |
203 | EXPORT_SYMBOL(__vfs_setxattr); |
204 | |
205 | /** |
206 | * __vfs_setxattr_noperm - perform setxattr operation without performing |
207 | * permission checks. |
208 | * |
209 | * @idmap: idmap of the mount the inode was found from |
210 | * @dentry: object to perform setxattr on |
211 | * @name: xattr name to set |
212 | * @value: value to set @name to |
213 | * @size: size of @value |
214 | * @flags: flags to pass into filesystem operations |
215 | * |
216 | * returns the result of the internal setxattr or setsecurity operations. |
217 | * |
218 | * This function requires the caller to lock the inode's i_mutex before it |
219 | * is executed. It also assumes that the caller will make the appropriate |
220 | * permission checks. |
221 | */ |
222 | int __vfs_setxattr_noperm(struct mnt_idmap *idmap, |
223 | struct dentry *dentry, const char *name, |
224 | const void *value, size_t size, int flags) |
225 | { |
226 | struct inode *inode = dentry->d_inode; |
227 | int error = -EAGAIN; |
228 | int issec = !strncmp(name, XATTR_SECURITY_PREFIX, |
229 | XATTR_SECURITY_PREFIX_LEN); |
230 | |
231 | if (issec) |
232 | inode->i_flags &= ~S_NOSEC; |
233 | if (inode->i_opflags & IOP_XATTR) { |
234 | error = __vfs_setxattr(idmap, dentry, inode, name, value, |
235 | size, flags); |
236 | if (!error) { |
237 | fsnotify_xattr(dentry); |
238 | security_inode_post_setxattr(dentry, name, value, |
239 | size, flags); |
240 | } |
241 | } else { |
242 | if (unlikely(is_bad_inode(inode))) |
243 | return -EIO; |
244 | } |
245 | if (error == -EAGAIN) { |
246 | error = -EOPNOTSUPP; |
247 | |
248 | if (issec) { |
249 | const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; |
250 | |
251 | error = security_inode_setsecurity(inode, name: suffix, value, |
252 | size, flags); |
253 | if (!error) |
254 | fsnotify_xattr(dentry); |
255 | } |
256 | } |
257 | |
258 | return error; |
259 | } |
260 | |
261 | /** |
262 | * __vfs_setxattr_locked - set an extended attribute while holding the inode |
263 | * lock |
264 | * |
265 | * @idmap: idmap of the mount of the target inode |
266 | * @dentry: object to perform setxattr on |
267 | * @name: xattr name to set |
268 | * @value: value to set @name to |
269 | * @size: size of @value |
270 | * @flags: flags to pass into filesystem operations |
271 | * @delegated_inode: on return, will contain an inode pointer that |
272 | * a delegation was broken on, NULL if none. |
273 | */ |
274 | int |
275 | __vfs_setxattr_locked(struct mnt_idmap *idmap, struct dentry *dentry, |
276 | const char *name, const void *value, size_t size, |
277 | int flags, struct inode **delegated_inode) |
278 | { |
279 | struct inode *inode = dentry->d_inode; |
280 | int error; |
281 | |
282 | error = xattr_permission(idmap, inode, name, MAY_WRITE); |
283 | if (error) |
284 | return error; |
285 | |
286 | error = security_inode_setxattr(idmap, dentry, name, value, size, |
287 | flags); |
288 | if (error) |
289 | goto out; |
290 | |
291 | error = try_break_deleg(inode, delegated_inode); |
292 | if (error) |
293 | goto out; |
294 | |
295 | error = __vfs_setxattr_noperm(idmap, dentry, name, value, |
296 | size, flags); |
297 | |
298 | out: |
299 | return error; |
300 | } |
301 | EXPORT_SYMBOL_GPL(__vfs_setxattr_locked); |
302 | |
303 | int |
304 | vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, |
305 | const char *name, const void *value, size_t size, int flags) |
306 | { |
307 | struct inode *inode = dentry->d_inode; |
308 | struct inode *delegated_inode = NULL; |
309 | const void *orig_value = value; |
310 | int error; |
311 | |
312 | if (size && strcmp(name, XATTR_NAME_CAPS) == 0) { |
313 | error = cap_convert_nscap(idmap, dentry, ivalue: &value, size); |
314 | if (error < 0) |
315 | return error; |
316 | size = error; |
317 | } |
318 | |
319 | retry_deleg: |
320 | inode_lock(inode); |
321 | error = __vfs_setxattr_locked(idmap, dentry, name, value, size, |
322 | flags, &delegated_inode); |
323 | inode_unlock(inode); |
324 | |
325 | if (delegated_inode) { |
326 | error = break_deleg_wait(delegated_inode: &delegated_inode); |
327 | if (!error) |
328 | goto retry_deleg; |
329 | } |
330 | if (value != orig_value) |
331 | kfree(objp: value); |
332 | |
333 | return error; |
334 | } |
335 | EXPORT_SYMBOL_GPL(vfs_setxattr); |
336 | |
337 | static ssize_t |
338 | xattr_getsecurity(struct mnt_idmap *idmap, struct inode *inode, |
339 | const char *name, void *value, size_t size) |
340 | { |
341 | void *buffer = NULL; |
342 | ssize_t len; |
343 | |
344 | if (!value || !size) { |
345 | len = security_inode_getsecurity(idmap, inode, name, |
346 | buffer: &buffer, alloc: false); |
347 | goto out_noalloc; |
348 | } |
349 | |
350 | len = security_inode_getsecurity(idmap, inode, name, buffer: &buffer, |
351 | alloc: true); |
352 | if (len < 0) |
353 | return len; |
354 | if (size < len) { |
355 | len = -ERANGE; |
356 | goto out; |
357 | } |
358 | memcpy(value, buffer, len); |
359 | out: |
360 | kfree(objp: buffer); |
361 | out_noalloc: |
362 | return len; |
363 | } |
364 | |
365 | /* |
366 | * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr |
367 | * |
368 | * Allocate memory, if not already allocated, or re-allocate correct size, |
369 | * before retrieving the extended attribute. The xattr value buffer should |
370 | * always be freed by the caller, even on error. |
371 | * |
372 | * Returns the result of alloc, if failed, or the getxattr operation. |
373 | */ |
374 | int |
375 | vfs_getxattr_alloc(struct mnt_idmap *idmap, struct dentry *dentry, |
376 | const char *name, char **xattr_value, size_t xattr_size, |
377 | gfp_t flags) |
378 | { |
379 | const struct xattr_handler *handler; |
380 | struct inode *inode = dentry->d_inode; |
381 | char *value = *xattr_value; |
382 | int error; |
383 | |
384 | error = xattr_permission(idmap, inode, name, MAY_READ); |
385 | if (error) |
386 | return error; |
387 | |
388 | handler = xattr_resolve_name(inode, name: &name); |
389 | if (IS_ERR(ptr: handler)) |
390 | return PTR_ERR(ptr: handler); |
391 | if (!handler->get) |
392 | return -EOPNOTSUPP; |
393 | error = handler->get(handler, dentry, inode, name, NULL, 0); |
394 | if (error < 0) |
395 | return error; |
396 | |
397 | if (!value || (error > xattr_size)) { |
398 | value = krealloc(objp: *xattr_value, new_size: error + 1, flags); |
399 | if (!value) |
400 | return -ENOMEM; |
401 | memset(value, 0, error + 1); |
402 | } |
403 | |
404 | error = handler->get(handler, dentry, inode, name, value, error); |
405 | *xattr_value = value; |
406 | return error; |
407 | } |
408 | |
409 | ssize_t |
410 | __vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name, |
411 | void *value, size_t size) |
412 | { |
413 | const struct xattr_handler *handler; |
414 | |
415 | if (is_posix_acl_xattr(name)) |
416 | return -EOPNOTSUPP; |
417 | |
418 | handler = xattr_resolve_name(inode, name: &name); |
419 | if (IS_ERR(ptr: handler)) |
420 | return PTR_ERR(ptr: handler); |
421 | if (!handler->get) |
422 | return -EOPNOTSUPP; |
423 | return handler->get(handler, dentry, inode, name, value, size); |
424 | } |
425 | EXPORT_SYMBOL(__vfs_getxattr); |
426 | |
427 | ssize_t |
428 | vfs_getxattr(struct mnt_idmap *idmap, struct dentry *dentry, |
429 | const char *name, void *value, size_t size) |
430 | { |
431 | struct inode *inode = dentry->d_inode; |
432 | int error; |
433 | |
434 | error = xattr_permission(idmap, inode, name, MAY_READ); |
435 | if (error) |
436 | return error; |
437 | |
438 | error = security_inode_getxattr(dentry, name); |
439 | if (error) |
440 | return error; |
441 | |
442 | if (!strncmp(name, XATTR_SECURITY_PREFIX, |
443 | XATTR_SECURITY_PREFIX_LEN)) { |
444 | const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; |
445 | int ret = xattr_getsecurity(idmap, inode, name: suffix, value, |
446 | size); |
447 | /* |
448 | * Only overwrite the return value if a security module |
449 | * is actually active. |
450 | */ |
451 | if (ret == -EOPNOTSUPP) |
452 | goto nolsm; |
453 | return ret; |
454 | } |
455 | nolsm: |
456 | return __vfs_getxattr(dentry, inode, name, value, size); |
457 | } |
458 | EXPORT_SYMBOL_GPL(vfs_getxattr); |
459 | |
460 | /** |
461 | * vfs_listxattr - retrieve \0 separated list of xattr names |
462 | * @dentry: the dentry from whose inode the xattr names are retrieved |
463 | * @list: buffer to store xattr names into |
464 | * @size: size of the buffer |
465 | * |
466 | * This function returns the names of all xattrs associated with the |
467 | * inode of @dentry. |
468 | * |
469 | * Note, for legacy reasons the vfs_listxattr() function lists POSIX |
470 | * ACLs as well. Since POSIX ACLs are decoupled from IOP_XATTR the |
471 | * vfs_listxattr() function doesn't check for this flag since a |
472 | * filesystem could implement POSIX ACLs without implementing any other |
473 | * xattrs. |
474 | * |
475 | * However, since all codepaths that remove IOP_XATTR also assign of |
476 | * inode operations that either don't implement or implement a stub |
477 | * ->listxattr() operation. |
478 | * |
479 | * Return: On success, the size of the buffer that was used. On error a |
480 | * negative error code. |
481 | */ |
482 | ssize_t |
483 | vfs_listxattr(struct dentry *dentry, char *list, size_t size) |
484 | { |
485 | struct inode *inode = d_inode(dentry); |
486 | ssize_t error; |
487 | |
488 | error = security_inode_listxattr(dentry); |
489 | if (error) |
490 | return error; |
491 | |
492 | if (inode->i_op->listxattr) { |
493 | error = inode->i_op->listxattr(dentry, list, size); |
494 | } else { |
495 | error = security_inode_listsecurity(inode, buffer: list, buffer_size: size); |
496 | if (size && error > size) |
497 | error = -ERANGE; |
498 | } |
499 | return error; |
500 | } |
501 | EXPORT_SYMBOL_GPL(vfs_listxattr); |
502 | |
503 | int |
504 | __vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, |
505 | const char *name) |
506 | { |
507 | struct inode *inode = d_inode(dentry); |
508 | const struct xattr_handler *handler; |
509 | |
510 | if (is_posix_acl_xattr(name)) |
511 | return -EOPNOTSUPP; |
512 | |
513 | handler = xattr_resolve_name(inode, name: &name); |
514 | if (IS_ERR(ptr: handler)) |
515 | return PTR_ERR(ptr: handler); |
516 | if (!handler->set) |
517 | return -EOPNOTSUPP; |
518 | return handler->set(handler, idmap, dentry, inode, name, NULL, 0, |
519 | XATTR_REPLACE); |
520 | } |
521 | EXPORT_SYMBOL(__vfs_removexattr); |
522 | |
523 | /** |
524 | * __vfs_removexattr_locked - set an extended attribute while holding the inode |
525 | * lock |
526 | * |
527 | * @idmap: idmap of the mount of the target inode |
528 | * @dentry: object to perform setxattr on |
529 | * @name: name of xattr to remove |
530 | * @delegated_inode: on return, will contain an inode pointer that |
531 | * a delegation was broken on, NULL if none. |
532 | */ |
533 | int |
534 | __vfs_removexattr_locked(struct mnt_idmap *idmap, |
535 | struct dentry *dentry, const char *name, |
536 | struct inode **delegated_inode) |
537 | { |
538 | struct inode *inode = dentry->d_inode; |
539 | int error; |
540 | |
541 | error = xattr_permission(idmap, inode, name, MAY_WRITE); |
542 | if (error) |
543 | return error; |
544 | |
545 | error = security_inode_removexattr(idmap, dentry, name); |
546 | if (error) |
547 | goto out; |
548 | |
549 | error = try_break_deleg(inode, delegated_inode); |
550 | if (error) |
551 | goto out; |
552 | |
553 | error = __vfs_removexattr(idmap, dentry, name); |
554 | if (error) |
555 | return error; |
556 | |
557 | fsnotify_xattr(dentry); |
558 | security_inode_post_removexattr(dentry, name); |
559 | |
560 | out: |
561 | return error; |
562 | } |
563 | EXPORT_SYMBOL_GPL(__vfs_removexattr_locked); |
564 | |
565 | int |
566 | vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, |
567 | const char *name) |
568 | { |
569 | struct inode *inode = dentry->d_inode; |
570 | struct inode *delegated_inode = NULL; |
571 | int error; |
572 | |
573 | retry_deleg: |
574 | inode_lock(inode); |
575 | error = __vfs_removexattr_locked(idmap, dentry, |
576 | name, &delegated_inode); |
577 | inode_unlock(inode); |
578 | |
579 | if (delegated_inode) { |
580 | error = break_deleg_wait(delegated_inode: &delegated_inode); |
581 | if (!error) |
582 | goto retry_deleg; |
583 | } |
584 | |
585 | return error; |
586 | } |
587 | EXPORT_SYMBOL_GPL(vfs_removexattr); |
588 | |
589 | /* |
590 | * Extended attribute SET operations |
591 | */ |
592 | |
593 | int setxattr_copy(const char __user *name, struct xattr_ctx *ctx) |
594 | { |
595 | int error; |
596 | |
597 | if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE)) |
598 | return -EINVAL; |
599 | |
600 | error = strncpy_from_user(dst: ctx->kname->name, src: name, |
601 | count: sizeof(ctx->kname->name)); |
602 | if (error == 0 || error == sizeof(ctx->kname->name)) |
603 | return -ERANGE; |
604 | if (error < 0) |
605 | return error; |
606 | |
607 | error = 0; |
608 | if (ctx->size) { |
609 | if (ctx->size > XATTR_SIZE_MAX) |
610 | return -E2BIG; |
611 | |
612 | ctx->kvalue = vmemdup_user(ctx->cvalue, ctx->size); |
613 | if (IS_ERR(ptr: ctx->kvalue)) { |
614 | error = PTR_ERR(ptr: ctx->kvalue); |
615 | ctx->kvalue = NULL; |
616 | } |
617 | } |
618 | |
619 | return error; |
620 | } |
621 | |
622 | int do_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, |
623 | struct xattr_ctx *ctx) |
624 | { |
625 | if (is_posix_acl_xattr(name: ctx->kname->name)) |
626 | return do_set_acl(idmap, dentry, acl_name: ctx->kname->name, |
627 | kvalue: ctx->kvalue, size: ctx->size); |
628 | |
629 | return vfs_setxattr(idmap, dentry, ctx->kname->name, |
630 | ctx->kvalue, ctx->size, ctx->flags); |
631 | } |
632 | |
633 | static long |
634 | setxattr(struct mnt_idmap *idmap, struct dentry *d, |
635 | const char __user *name, const void __user *value, size_t size, |
636 | int flags) |
637 | { |
638 | struct xattr_name kname; |
639 | struct xattr_ctx ctx = { |
640 | .cvalue = value, |
641 | .kvalue = NULL, |
642 | .size = size, |
643 | .kname = &kname, |
644 | .flags = flags, |
645 | }; |
646 | int error; |
647 | |
648 | error = setxattr_copy(name, ctx: &ctx); |
649 | if (error) |
650 | return error; |
651 | |
652 | error = do_setxattr(idmap, dentry: d, ctx: &ctx); |
653 | |
654 | kvfree(addr: ctx.kvalue); |
655 | return error; |
656 | } |
657 | |
658 | static int path_setxattr(const char __user *pathname, |
659 | const char __user *name, const void __user *value, |
660 | size_t size, int flags, unsigned int lookup_flags) |
661 | { |
662 | struct path path; |
663 | int error; |
664 | |
665 | retry: |
666 | error = user_path_at(AT_FDCWD, name: pathname, flags: lookup_flags, path: &path); |
667 | if (error) |
668 | return error; |
669 | error = mnt_want_write(mnt: path.mnt); |
670 | if (!error) { |
671 | error = setxattr(idmap: mnt_idmap(mnt: path.mnt), d: path.dentry, name, |
672 | value, size, flags); |
673 | mnt_drop_write(mnt: path.mnt); |
674 | } |
675 | path_put(&path); |
676 | if (retry_estale(error, flags: lookup_flags)) { |
677 | lookup_flags |= LOOKUP_REVAL; |
678 | goto retry; |
679 | } |
680 | return error; |
681 | } |
682 | |
683 | SYSCALL_DEFINE5(setxattr, const char __user *, pathname, |
684 | const char __user *, name, const void __user *, value, |
685 | size_t, size, int, flags) |
686 | { |
687 | return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW); |
688 | } |
689 | |
690 | SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname, |
691 | const char __user *, name, const void __user *, value, |
692 | size_t, size, int, flags) |
693 | { |
694 | return path_setxattr(pathname, name, value, size, flags, lookup_flags: 0); |
695 | } |
696 | |
697 | SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name, |
698 | const void __user *,value, size_t, size, int, flags) |
699 | { |
700 | struct fd f = fdget(fd); |
701 | int error = -EBADF; |
702 | |
703 | if (!f.file) |
704 | return error; |
705 | audit_file(file: f.file); |
706 | error = mnt_want_write_file(file: f.file); |
707 | if (!error) { |
708 | error = setxattr(idmap: file_mnt_idmap(file: f.file), |
709 | d: f.file->f_path.dentry, name, |
710 | value, size, flags); |
711 | mnt_drop_write_file(file: f.file); |
712 | } |
713 | fdput(fd: f); |
714 | return error; |
715 | } |
716 | |
717 | /* |
718 | * Extended attribute GET operations |
719 | */ |
720 | ssize_t |
721 | do_getxattr(struct mnt_idmap *idmap, struct dentry *d, |
722 | struct xattr_ctx *ctx) |
723 | { |
724 | ssize_t error; |
725 | char *kname = ctx->kname->name; |
726 | |
727 | if (ctx->size) { |
728 | if (ctx->size > XATTR_SIZE_MAX) |
729 | ctx->size = XATTR_SIZE_MAX; |
730 | ctx->kvalue = kvzalloc(size: ctx->size, GFP_KERNEL); |
731 | if (!ctx->kvalue) |
732 | return -ENOMEM; |
733 | } |
734 | |
735 | if (is_posix_acl_xattr(name: ctx->kname->name)) |
736 | error = do_get_acl(idmap, dentry: d, acl_name: kname, kvalue: ctx->kvalue, size: ctx->size); |
737 | else |
738 | error = vfs_getxattr(idmap, d, kname, ctx->kvalue, ctx->size); |
739 | if (error > 0) { |
740 | if (ctx->size && copy_to_user(to: ctx->value, from: ctx->kvalue, n: error)) |
741 | error = -EFAULT; |
742 | } else if (error == -ERANGE && ctx->size >= XATTR_SIZE_MAX) { |
743 | /* The file system tried to returned a value bigger |
744 | than XATTR_SIZE_MAX bytes. Not possible. */ |
745 | error = -E2BIG; |
746 | } |
747 | |
748 | return error; |
749 | } |
750 | |
751 | static ssize_t |
752 | getxattr(struct mnt_idmap *idmap, struct dentry *d, |
753 | const char __user *name, void __user *value, size_t size) |
754 | { |
755 | ssize_t error; |
756 | struct xattr_name kname; |
757 | struct xattr_ctx ctx = { |
758 | .value = value, |
759 | .kvalue = NULL, |
760 | .size = size, |
761 | .kname = &kname, |
762 | .flags = 0, |
763 | }; |
764 | |
765 | error = strncpy_from_user(dst: kname.name, src: name, count: sizeof(kname.name)); |
766 | if (error == 0 || error == sizeof(kname.name)) |
767 | error = -ERANGE; |
768 | if (error < 0) |
769 | return error; |
770 | |
771 | error = do_getxattr(idmap, d, ctx: &ctx); |
772 | |
773 | kvfree(addr: ctx.kvalue); |
774 | return error; |
775 | } |
776 | |
777 | static ssize_t path_getxattr(const char __user *pathname, |
778 | const char __user *name, void __user *value, |
779 | size_t size, unsigned int lookup_flags) |
780 | { |
781 | struct path path; |
782 | ssize_t error; |
783 | retry: |
784 | error = user_path_at(AT_FDCWD, name: pathname, flags: lookup_flags, path: &path); |
785 | if (error) |
786 | return error; |
787 | error = getxattr(idmap: mnt_idmap(mnt: path.mnt), d: path.dentry, name, value, size); |
788 | path_put(&path); |
789 | if (retry_estale(error, flags: lookup_flags)) { |
790 | lookup_flags |= LOOKUP_REVAL; |
791 | goto retry; |
792 | } |
793 | return error; |
794 | } |
795 | |
796 | SYSCALL_DEFINE4(getxattr, const char __user *, pathname, |
797 | const char __user *, name, void __user *, value, size_t, size) |
798 | { |
799 | return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW); |
800 | } |
801 | |
802 | SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname, |
803 | const char __user *, name, void __user *, value, size_t, size) |
804 | { |
805 | return path_getxattr(pathname, name, value, size, lookup_flags: 0); |
806 | } |
807 | |
808 | SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name, |
809 | void __user *, value, size_t, size) |
810 | { |
811 | struct fd f = fdget(fd); |
812 | ssize_t error = -EBADF; |
813 | |
814 | if (!f.file) |
815 | return error; |
816 | audit_file(file: f.file); |
817 | error = getxattr(idmap: file_mnt_idmap(file: f.file), d: f.file->f_path.dentry, |
818 | name, value, size); |
819 | fdput(fd: f); |
820 | return error; |
821 | } |
822 | |
823 | /* |
824 | * Extended attribute LIST operations |
825 | */ |
826 | static ssize_t |
827 | listxattr(struct dentry *d, char __user *list, size_t size) |
828 | { |
829 | ssize_t error; |
830 | char *klist = NULL; |
831 | |
832 | if (size) { |
833 | if (size > XATTR_LIST_MAX) |
834 | size = XATTR_LIST_MAX; |
835 | klist = kvmalloc(size, GFP_KERNEL); |
836 | if (!klist) |
837 | return -ENOMEM; |
838 | } |
839 | |
840 | error = vfs_listxattr(d, klist, size); |
841 | if (error > 0) { |
842 | if (size && copy_to_user(to: list, from: klist, n: error)) |
843 | error = -EFAULT; |
844 | } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { |
845 | /* The file system tried to returned a list bigger |
846 | than XATTR_LIST_MAX bytes. Not possible. */ |
847 | error = -E2BIG; |
848 | } |
849 | |
850 | kvfree(addr: klist); |
851 | |
852 | return error; |
853 | } |
854 | |
855 | static ssize_t path_listxattr(const char __user *pathname, char __user *list, |
856 | size_t size, unsigned int lookup_flags) |
857 | { |
858 | struct path path; |
859 | ssize_t error; |
860 | retry: |
861 | error = user_path_at(AT_FDCWD, name: pathname, flags: lookup_flags, path: &path); |
862 | if (error) |
863 | return error; |
864 | error = listxattr(d: path.dentry, list, size); |
865 | path_put(&path); |
866 | if (retry_estale(error, flags: lookup_flags)) { |
867 | lookup_flags |= LOOKUP_REVAL; |
868 | goto retry; |
869 | } |
870 | return error; |
871 | } |
872 | |
873 | SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list, |
874 | size_t, size) |
875 | { |
876 | return path_listxattr(pathname, list, size, LOOKUP_FOLLOW); |
877 | } |
878 | |
879 | SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list, |
880 | size_t, size) |
881 | { |
882 | return path_listxattr(pathname, list, size, lookup_flags: 0); |
883 | } |
884 | |
885 | SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size) |
886 | { |
887 | struct fd f = fdget(fd); |
888 | ssize_t error = -EBADF; |
889 | |
890 | if (!f.file) |
891 | return error; |
892 | audit_file(file: f.file); |
893 | error = listxattr(d: f.file->f_path.dentry, list, size); |
894 | fdput(fd: f); |
895 | return error; |
896 | } |
897 | |
898 | /* |
899 | * Extended attribute REMOVE operations |
900 | */ |
901 | static long |
902 | removexattr(struct mnt_idmap *idmap, struct dentry *d, |
903 | const char __user *name) |
904 | { |
905 | int error; |
906 | char kname[XATTR_NAME_MAX + 1]; |
907 | |
908 | error = strncpy_from_user(dst: kname, src: name, count: sizeof(kname)); |
909 | if (error == 0 || error == sizeof(kname)) |
910 | error = -ERANGE; |
911 | if (error < 0) |
912 | return error; |
913 | |
914 | if (is_posix_acl_xattr(name: kname)) |
915 | return vfs_remove_acl(idmap, dentry: d, acl_name: kname); |
916 | |
917 | return vfs_removexattr(idmap, d, kname); |
918 | } |
919 | |
920 | static int path_removexattr(const char __user *pathname, |
921 | const char __user *name, unsigned int lookup_flags) |
922 | { |
923 | struct path path; |
924 | int error; |
925 | retry: |
926 | error = user_path_at(AT_FDCWD, name: pathname, flags: lookup_flags, path: &path); |
927 | if (error) |
928 | return error; |
929 | error = mnt_want_write(mnt: path.mnt); |
930 | if (!error) { |
931 | error = removexattr(idmap: mnt_idmap(mnt: path.mnt), d: path.dentry, name); |
932 | mnt_drop_write(mnt: path.mnt); |
933 | } |
934 | path_put(&path); |
935 | if (retry_estale(error, flags: lookup_flags)) { |
936 | lookup_flags |= LOOKUP_REVAL; |
937 | goto retry; |
938 | } |
939 | return error; |
940 | } |
941 | |
942 | SYSCALL_DEFINE2(removexattr, const char __user *, pathname, |
943 | const char __user *, name) |
944 | { |
945 | return path_removexattr(pathname, name, LOOKUP_FOLLOW); |
946 | } |
947 | |
948 | SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname, |
949 | const char __user *, name) |
950 | { |
951 | return path_removexattr(pathname, name, lookup_flags: 0); |
952 | } |
953 | |
954 | SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name) |
955 | { |
956 | struct fd f = fdget(fd); |
957 | int error = -EBADF; |
958 | |
959 | if (!f.file) |
960 | return error; |
961 | audit_file(file: f.file); |
962 | error = mnt_want_write_file(file: f.file); |
963 | if (!error) { |
964 | error = removexattr(idmap: file_mnt_idmap(file: f.file), |
965 | d: f.file->f_path.dentry, name); |
966 | mnt_drop_write_file(file: f.file); |
967 | } |
968 | fdput(fd: f); |
969 | return error; |
970 | } |
971 | |
972 | int xattr_list_one(char **buffer, ssize_t *remaining_size, const char *name) |
973 | { |
974 | size_t len; |
975 | |
976 | len = strlen(name) + 1; |
977 | if (*buffer) { |
978 | if (*remaining_size < len) |
979 | return -ERANGE; |
980 | memcpy(*buffer, name, len); |
981 | *buffer += len; |
982 | } |
983 | *remaining_size -= len; |
984 | return 0; |
985 | } |
986 | |
987 | /** |
988 | * generic_listxattr - run through a dentry's xattr list() operations |
989 | * @dentry: dentry to list the xattrs |
990 | * @buffer: result buffer |
991 | * @buffer_size: size of @buffer |
992 | * |
993 | * Combine the results of the list() operation from every xattr_handler in the |
994 | * xattr_handler stack. |
995 | * |
996 | * Note that this will not include the entries for POSIX ACLs. |
997 | */ |
998 | ssize_t |
999 | generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) |
1000 | { |
1001 | const struct xattr_handler *handler, * const *handlers = dentry->d_sb->s_xattr; |
1002 | ssize_t remaining_size = buffer_size; |
1003 | int err = 0; |
1004 | |
1005 | for_each_xattr_handler(handlers, handler) { |
1006 | if (!handler->name || (handler->list && !handler->list(dentry))) |
1007 | continue; |
1008 | err = xattr_list_one(buffer: &buffer, remaining_size: &remaining_size, name: handler->name); |
1009 | if (err) |
1010 | return err; |
1011 | } |
1012 | |
1013 | return err ? err : buffer_size - remaining_size; |
1014 | } |
1015 | EXPORT_SYMBOL(generic_listxattr); |
1016 | |
1017 | /** |
1018 | * xattr_full_name - Compute full attribute name from suffix |
1019 | * |
1020 | * @handler: handler of the xattr_handler operation |
1021 | * @name: name passed to the xattr_handler operation |
1022 | * |
1023 | * The get and set xattr handler operations are called with the remainder of |
1024 | * the attribute name after skipping the handler's prefix: for example, "foo" |
1025 | * is passed to the get operation of a handler with prefix "user." to get |
1026 | * attribute "user.foo". The full name is still "there" in the name though. |
1027 | * |
1028 | * Note: the list xattr handler operation when called from the vfs is passed a |
1029 | * NULL name; some file systems use this operation internally, with varying |
1030 | * semantics. |
1031 | */ |
1032 | const char *xattr_full_name(const struct xattr_handler *handler, |
1033 | const char *name) |
1034 | { |
1035 | size_t prefix_len = strlen(xattr_prefix(handler)); |
1036 | |
1037 | return name - prefix_len; |
1038 | } |
1039 | EXPORT_SYMBOL(xattr_full_name); |
1040 | |
1041 | /** |
1042 | * simple_xattr_space - estimate the memory used by a simple xattr |
1043 | * @name: the full name of the xattr |
1044 | * @size: the size of its value |
1045 | * |
1046 | * This takes no account of how much larger the two slab objects actually are: |
1047 | * that would depend on the slab implementation, when what is required is a |
1048 | * deterministic number, which grows with name length and size and quantity. |
1049 | * |
1050 | * Return: The approximate number of bytes of memory used by such an xattr. |
1051 | */ |
1052 | size_t simple_xattr_space(const char *name, size_t size) |
1053 | { |
1054 | /* |
1055 | * Use "40" instead of sizeof(struct simple_xattr), to return the |
1056 | * same result on 32-bit and 64-bit, and even if simple_xattr grows. |
1057 | */ |
1058 | return 40 + size + strlen(name); |
1059 | } |
1060 | |
1061 | /** |
1062 | * simple_xattr_free - free an xattr object |
1063 | * @xattr: the xattr object |
1064 | * |
1065 | * Free the xattr object. Can handle @xattr being NULL. |
1066 | */ |
1067 | void simple_xattr_free(struct simple_xattr *xattr) |
1068 | { |
1069 | if (xattr) |
1070 | kfree(objp: xattr->name); |
1071 | kvfree(addr: xattr); |
1072 | } |
1073 | |
1074 | /** |
1075 | * simple_xattr_alloc - allocate new xattr object |
1076 | * @value: value of the xattr object |
1077 | * @size: size of @value |
1078 | * |
1079 | * Allocate a new xattr object and initialize respective members. The caller is |
1080 | * responsible for handling the name of the xattr. |
1081 | * |
1082 | * Return: On success a new xattr object is returned. On failure NULL is |
1083 | * returned. |
1084 | */ |
1085 | struct simple_xattr *simple_xattr_alloc(const void *value, size_t size) |
1086 | { |
1087 | struct simple_xattr *new_xattr; |
1088 | size_t len; |
1089 | |
1090 | /* wrap around? */ |
1091 | len = sizeof(*new_xattr) + size; |
1092 | if (len < sizeof(*new_xattr)) |
1093 | return NULL; |
1094 | |
1095 | new_xattr = kvmalloc(size: len, GFP_KERNEL_ACCOUNT); |
1096 | if (!new_xattr) |
1097 | return NULL; |
1098 | |
1099 | new_xattr->size = size; |
1100 | memcpy(new_xattr->value, value, size); |
1101 | return new_xattr; |
1102 | } |
1103 | |
1104 | /** |
1105 | * rbtree_simple_xattr_cmp - compare xattr name with current rbtree xattr entry |
1106 | * @key: xattr name |
1107 | * @node: current node |
1108 | * |
1109 | * Compare the xattr name with the xattr name attached to @node in the rbtree. |
1110 | * |
1111 | * Return: Negative value if continuing left, positive if continuing right, 0 |
1112 | * if the xattr attached to @node matches @key. |
1113 | */ |
1114 | static int rbtree_simple_xattr_cmp(const void *key, const struct rb_node *node) |
1115 | { |
1116 | const char *xattr_name = key; |
1117 | const struct simple_xattr *xattr; |
1118 | |
1119 | xattr = rb_entry(node, struct simple_xattr, rb_node); |
1120 | return strcmp(xattr->name, xattr_name); |
1121 | } |
1122 | |
1123 | /** |
1124 | * rbtree_simple_xattr_node_cmp - compare two xattr rbtree nodes |
1125 | * @new_node: new node |
1126 | * @node: current node |
1127 | * |
1128 | * Compare the xattr attached to @new_node with the xattr attached to @node. |
1129 | * |
1130 | * Return: Negative value if continuing left, positive if continuing right, 0 |
1131 | * if the xattr attached to @new_node matches the xattr attached to @node. |
1132 | */ |
1133 | static int rbtree_simple_xattr_node_cmp(struct rb_node *new_node, |
1134 | const struct rb_node *node) |
1135 | { |
1136 | struct simple_xattr *xattr; |
1137 | xattr = rb_entry(new_node, struct simple_xattr, rb_node); |
1138 | return rbtree_simple_xattr_cmp(key: xattr->name, node); |
1139 | } |
1140 | |
1141 | /** |
1142 | * simple_xattr_get - get an xattr object |
1143 | * @xattrs: the header of the xattr object |
1144 | * @name: the name of the xattr to retrieve |
1145 | * @buffer: the buffer to store the value into |
1146 | * @size: the size of @buffer |
1147 | * |
1148 | * Try to find and retrieve the xattr object associated with @name. |
1149 | * If @buffer is provided store the value of @xattr in @buffer |
1150 | * otherwise just return the length. The size of @buffer is limited |
1151 | * to XATTR_SIZE_MAX which currently is 65536. |
1152 | * |
1153 | * Return: On success the length of the xattr value is returned. On error a |
1154 | * negative error code is returned. |
1155 | */ |
1156 | int simple_xattr_get(struct simple_xattrs *xattrs, const char *name, |
1157 | void *buffer, size_t size) |
1158 | { |
1159 | struct simple_xattr *xattr = NULL; |
1160 | struct rb_node *rbp; |
1161 | int ret = -ENODATA; |
1162 | |
1163 | read_lock(&xattrs->lock); |
1164 | rbp = rb_find(key: name, tree: &xattrs->rb_root, cmp: rbtree_simple_xattr_cmp); |
1165 | if (rbp) { |
1166 | xattr = rb_entry(rbp, struct simple_xattr, rb_node); |
1167 | ret = xattr->size; |
1168 | if (buffer) { |
1169 | if (size < xattr->size) |
1170 | ret = -ERANGE; |
1171 | else |
1172 | memcpy(buffer, xattr->value, xattr->size); |
1173 | } |
1174 | } |
1175 | read_unlock(&xattrs->lock); |
1176 | return ret; |
1177 | } |
1178 | |
1179 | /** |
1180 | * simple_xattr_set - set an xattr object |
1181 | * @xattrs: the header of the xattr object |
1182 | * @name: the name of the xattr to retrieve |
1183 | * @value: the value to store along the xattr |
1184 | * @size: the size of @value |
1185 | * @flags: the flags determining how to set the xattr |
1186 | * |
1187 | * Set a new xattr object. |
1188 | * If @value is passed a new xattr object will be allocated. If XATTR_REPLACE |
1189 | * is specified in @flags a matching xattr object for @name must already exist. |
1190 | * If it does it will be replaced with the new xattr object. If it doesn't we |
1191 | * fail. If XATTR_CREATE is specified and a matching xattr does already exist |
1192 | * we fail. If it doesn't we create a new xattr. If @flags is zero we simply |
1193 | * insert the new xattr replacing any existing one. |
1194 | * |
1195 | * If @value is empty and a matching xattr object is found we delete it if |
1196 | * XATTR_REPLACE is specified in @flags or @flags is zero. |
1197 | * |
1198 | * If @value is empty and no matching xattr object for @name is found we do |
1199 | * nothing if XATTR_CREATE is specified in @flags or @flags is zero. For |
1200 | * XATTR_REPLACE we fail as mentioned above. |
1201 | * |
1202 | * Return: On success, the removed or replaced xattr is returned, to be freed |
1203 | * by the caller; or NULL if none. On failure a negative error code is returned. |
1204 | */ |
1205 | struct simple_xattr *simple_xattr_set(struct simple_xattrs *xattrs, |
1206 | const char *name, const void *value, |
1207 | size_t size, int flags) |
1208 | { |
1209 | struct simple_xattr *old_xattr = NULL, *new_xattr = NULL; |
1210 | struct rb_node *parent = NULL, **rbp; |
1211 | int err = 0, ret; |
1212 | |
1213 | /* value == NULL means remove */ |
1214 | if (value) { |
1215 | new_xattr = simple_xattr_alloc(value, size); |
1216 | if (!new_xattr) |
1217 | return ERR_PTR(error: -ENOMEM); |
1218 | |
1219 | new_xattr->name = kstrdup(s: name, GFP_KERNEL_ACCOUNT); |
1220 | if (!new_xattr->name) { |
1221 | simple_xattr_free(xattr: new_xattr); |
1222 | return ERR_PTR(error: -ENOMEM); |
1223 | } |
1224 | } |
1225 | |
1226 | write_lock(&xattrs->lock); |
1227 | rbp = &xattrs->rb_root.rb_node; |
1228 | while (*rbp) { |
1229 | parent = *rbp; |
1230 | ret = rbtree_simple_xattr_cmp(key: name, node: *rbp); |
1231 | if (ret < 0) |
1232 | rbp = &(*rbp)->rb_left; |
1233 | else if (ret > 0) |
1234 | rbp = &(*rbp)->rb_right; |
1235 | else |
1236 | old_xattr = rb_entry(*rbp, struct simple_xattr, rb_node); |
1237 | if (old_xattr) |
1238 | break; |
1239 | } |
1240 | |
1241 | if (old_xattr) { |
1242 | /* Fail if XATTR_CREATE is requested and the xattr exists. */ |
1243 | if (flags & XATTR_CREATE) { |
1244 | err = -EEXIST; |
1245 | goto out_unlock; |
1246 | } |
1247 | |
1248 | if (new_xattr) |
1249 | rb_replace_node(victim: &old_xattr->rb_node, |
1250 | new: &new_xattr->rb_node, root: &xattrs->rb_root); |
1251 | else |
1252 | rb_erase(&old_xattr->rb_node, &xattrs->rb_root); |
1253 | } else { |
1254 | /* Fail if XATTR_REPLACE is requested but no xattr is found. */ |
1255 | if (flags & XATTR_REPLACE) { |
1256 | err = -ENODATA; |
1257 | goto out_unlock; |
1258 | } |
1259 | |
1260 | /* |
1261 | * If XATTR_CREATE or no flags are specified together with a |
1262 | * new value simply insert it. |
1263 | */ |
1264 | if (new_xattr) { |
1265 | rb_link_node(node: &new_xattr->rb_node, parent, rb_link: rbp); |
1266 | rb_insert_color(&new_xattr->rb_node, &xattrs->rb_root); |
1267 | } |
1268 | |
1269 | /* |
1270 | * If XATTR_CREATE or no flags are specified and neither an |
1271 | * old or new xattr exist then we don't need to do anything. |
1272 | */ |
1273 | } |
1274 | |
1275 | out_unlock: |
1276 | write_unlock(&xattrs->lock); |
1277 | if (!err) |
1278 | return old_xattr; |
1279 | simple_xattr_free(xattr: new_xattr); |
1280 | return ERR_PTR(error: err); |
1281 | } |
1282 | |
1283 | static bool xattr_is_trusted(const char *name) |
1284 | { |
1285 | return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN); |
1286 | } |
1287 | |
1288 | /** |
1289 | * simple_xattr_list - list all xattr objects |
1290 | * @inode: inode from which to get the xattrs |
1291 | * @xattrs: the header of the xattr object |
1292 | * @buffer: the buffer to store all xattrs into |
1293 | * @size: the size of @buffer |
1294 | * |
1295 | * List all xattrs associated with @inode. If @buffer is NULL we returned |
1296 | * the required size of the buffer. If @buffer is provided we store the |
1297 | * xattrs value into it provided it is big enough. |
1298 | * |
1299 | * Note, the number of xattr names that can be listed with listxattr(2) is |
1300 | * limited to XATTR_LIST_MAX aka 65536 bytes. If a larger buffer is passed |
1301 | * then vfs_listxattr() caps it to XATTR_LIST_MAX and if more xattr names |
1302 | * are found it will return -E2BIG. |
1303 | * |
1304 | * Return: On success the required size or the size of the copied xattrs is |
1305 | * returned. On error a negative error code is returned. |
1306 | */ |
1307 | ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, |
1308 | char *buffer, size_t size) |
1309 | { |
1310 | bool trusted = ns_capable_noaudit(ns: &init_user_ns, CAP_SYS_ADMIN); |
1311 | struct simple_xattr *xattr; |
1312 | struct rb_node *rbp; |
1313 | ssize_t remaining_size = size; |
1314 | int err = 0; |
1315 | |
1316 | err = posix_acl_listxattr(inode, buffer: &buffer, remaining_size: &remaining_size); |
1317 | if (err) |
1318 | return err; |
1319 | |
1320 | read_lock(&xattrs->lock); |
1321 | for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) { |
1322 | xattr = rb_entry(rbp, struct simple_xattr, rb_node); |
1323 | |
1324 | /* skip "trusted." attributes for unprivileged callers */ |
1325 | if (!trusted && xattr_is_trusted(name: xattr->name)) |
1326 | continue; |
1327 | |
1328 | err = xattr_list_one(buffer: &buffer, remaining_size: &remaining_size, name: xattr->name); |
1329 | if (err) |
1330 | break; |
1331 | } |
1332 | read_unlock(&xattrs->lock); |
1333 | |
1334 | return err ? err : size - remaining_size; |
1335 | } |
1336 | |
1337 | /** |
1338 | * rbtree_simple_xattr_less - compare two xattr rbtree nodes |
1339 | * @new_node: new node |
1340 | * @node: current node |
1341 | * |
1342 | * Compare the xattr attached to @new_node with the xattr attached to @node. |
1343 | * Note that this function technically tolerates duplicate entries. |
1344 | * |
1345 | * Return: True if insertion point in the rbtree is found. |
1346 | */ |
1347 | static bool rbtree_simple_xattr_less(struct rb_node *new_node, |
1348 | const struct rb_node *node) |
1349 | { |
1350 | return rbtree_simple_xattr_node_cmp(new_node, node) < 0; |
1351 | } |
1352 | |
1353 | /** |
1354 | * simple_xattr_add - add xattr objects |
1355 | * @xattrs: the header of the xattr object |
1356 | * @new_xattr: the xattr object to add |
1357 | * |
1358 | * Add an xattr object to @xattrs. This assumes no replacement or removal |
1359 | * of matching xattrs is wanted. Should only be called during inode |
1360 | * initialization when a few distinct initial xattrs are supposed to be set. |
1361 | */ |
1362 | void simple_xattr_add(struct simple_xattrs *xattrs, |
1363 | struct simple_xattr *new_xattr) |
1364 | { |
1365 | write_lock(&xattrs->lock); |
1366 | rb_add(node: &new_xattr->rb_node, tree: &xattrs->rb_root, less: rbtree_simple_xattr_less); |
1367 | write_unlock(&xattrs->lock); |
1368 | } |
1369 | |
1370 | /** |
1371 | * simple_xattrs_init - initialize new xattr header |
1372 | * @xattrs: header to initialize |
1373 | * |
1374 | * Initialize relevant fields of a an xattr header. |
1375 | */ |
1376 | void simple_xattrs_init(struct simple_xattrs *xattrs) |
1377 | { |
1378 | xattrs->rb_root = RB_ROOT; |
1379 | rwlock_init(&xattrs->lock); |
1380 | } |
1381 | |
1382 | /** |
1383 | * simple_xattrs_free - free xattrs |
1384 | * @xattrs: xattr header whose xattrs to destroy |
1385 | * @freed_space: approximate number of bytes of memory freed from @xattrs |
1386 | * |
1387 | * Destroy all xattrs in @xattr. When this is called no one can hold a |
1388 | * reference to any of the xattrs anymore. |
1389 | */ |
1390 | void simple_xattrs_free(struct simple_xattrs *xattrs, size_t *freed_space) |
1391 | { |
1392 | struct rb_node *rbp; |
1393 | |
1394 | if (freed_space) |
1395 | *freed_space = 0; |
1396 | rbp = rb_first(&xattrs->rb_root); |
1397 | while (rbp) { |
1398 | struct simple_xattr *xattr; |
1399 | struct rb_node *rbp_next; |
1400 | |
1401 | rbp_next = rb_next(rbp); |
1402 | xattr = rb_entry(rbp, struct simple_xattr, rb_node); |
1403 | rb_erase(&xattr->rb_node, &xattrs->rb_root); |
1404 | if (freed_space) |
1405 | *freed_space += simple_xattr_space(name: xattr->name, |
1406 | size: xattr->size); |
1407 | simple_xattr_free(xattr); |
1408 | rbp = rbp_next; |
1409 | } |
1410 | } |
1411 | |