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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/slab.h> | |
13 | #include <linux/file.h> | |
14 | #include <linux/xattr.h> | |
15 | #include <linux/mount.h> | |
16 | #include <linux/namei.h> | |
17 | #include <linux/security.h> | |
18 | #include <linux/evm.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 | static const char * | |
29 | strcmp_prefix(const char *a, const char *a_prefix) | |
30 | { | |
31 | while (*a_prefix && *a == *a_prefix) { | |
32 | a++; | |
33 | a_prefix++; | |
34 | } | |
35 | return *a_prefix ? NULL : a; | |
36 | } | |
37 | ||
38 | /* | |
39 | * In order to implement different sets of xattr operations for each xattr | |
40 | * prefix, a filesystem should create a null-terminated array of struct | |
41 | * xattr_handler (one for each prefix) and hang a pointer to it off of the | |
42 | * s_xattr field of the superblock. | |
43 | */ | |
44 | #define for_each_xattr_handler(handlers, handler) \ | |
45 | if (handlers) \ | |
46 | for ((handler) = *(handlers)++; \ | |
47 | (handler) != NULL; \ | |
48 | (handler) = *(handlers)++) | |
49 | ||
50 | /* | |
51 | * Find the xattr_handler with the matching prefix. | |
52 | */ | |
53 | static const struct xattr_handler * | |
54 | xattr_resolve_name(struct inode *inode, const char **name) | |
55 | { | |
56 | const struct xattr_handler **handlers = inode->i_sb->s_xattr; | |
57 | const struct xattr_handler *handler; | |
58 | ||
59 | if (!(inode->i_opflags & IOP_XATTR)) { | |
60 | if (unlikely(is_bad_inode(inode))) | |
61 | return ERR_PTR(-EIO); | |
62 | return ERR_PTR(-EOPNOTSUPP); | |
63 | } | |
64 | for_each_xattr_handler(handlers, handler) { | |
65 | const char *n; | |
66 | ||
67 | n = strcmp_prefix(*name, xattr_prefix(handler)); | |
68 | if (n) { | |
69 | if (!handler->prefix ^ !*n) { | |
70 | if (*n) | |
71 | continue; | |
72 | return ERR_PTR(-EINVAL); | |
73 | } | |
74 | *name = n; | |
75 | return handler; | |
76 | } | |
77 | } | |
78 | return ERR_PTR(-EOPNOTSUPP); | |
79 | } | |
80 | ||
81 | /* | |
82 | * Check permissions for extended attribute access. This is a bit complicated | |
83 | * because different namespaces have very different rules. | |
84 | */ | |
85 | static int | |
86 | xattr_permission(struct inode *inode, const char *name, int mask) | |
87 | { | |
88 | /* | |
89 | * We can never set or remove an extended attribute on a read-only | |
90 | * filesystem or on an immutable / append-only inode. | |
91 | */ | |
92 | if (mask & MAY_WRITE) { | |
93 | if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) | |
94 | return -EPERM; | |
95 | /* | |
96 | * Updating an xattr will likely cause i_uid and i_gid | |
97 | * to be writen back improperly if their true value is | |
98 | * unknown to the vfs. | |
99 | */ | |
100 | if (HAS_UNMAPPED_ID(inode)) | |
101 | return -EPERM; | |
102 | } | |
103 | ||
104 | /* | |
105 | * No restriction for security.* and system.* from the VFS. Decision | |
106 | * on these is left to the underlying filesystem / security module. | |
107 | */ | |
108 | if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) || | |
109 | !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
110 | return 0; | |
111 | ||
112 | /* | |
113 | * The trusted.* namespace can only be accessed by privileged users. | |
114 | */ | |
115 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) { | |
116 | if (!capable(CAP_SYS_ADMIN)) | |
117 | return (mask & MAY_WRITE) ? -EPERM : -ENODATA; | |
118 | return 0; | |
119 | } | |
120 | ||
121 | /* | |
122 | * In the user.* namespace, only regular files and directories can have | |
123 | * extended attributes. For sticky directories, only the owner and | |
124 | * privileged users can write attributes. | |
125 | */ | |
126 | if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) { | |
127 | if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) | |
128 | return (mask & MAY_WRITE) ? -EPERM : -ENODATA; | |
129 | if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) && | |
130 | (mask & MAY_WRITE) && !inode_owner_or_capable(inode)) | |
131 | return -EPERM; | |
132 | } | |
133 | ||
134 | return inode_permission(inode, mask); | |
135 | } | |
136 | ||
137 | int | |
138 | __vfs_setxattr(struct dentry *dentry, struct inode *inode, const char *name, | |
139 | const void *value, size_t size, int flags) | |
140 | { | |
141 | const struct xattr_handler *handler; | |
142 | ||
143 | handler = xattr_resolve_name(inode, &name); | |
144 | if (IS_ERR(handler)) | |
145 | return PTR_ERR(handler); | |
146 | if (!handler->set) | |
147 | return -EOPNOTSUPP; | |
148 | if (size == 0) | |
149 | value = ""; /* empty EA, do not remove */ | |
150 | return handler->set(handler, dentry, inode, name, value, size, flags); | |
151 | } | |
152 | EXPORT_SYMBOL(__vfs_setxattr); | |
153 | ||
154 | /** | |
155 | * __vfs_setxattr_noperm - perform setxattr operation without performing | |
156 | * permission checks. | |
157 | * | |
158 | * @dentry - object to perform setxattr on | |
159 | * @name - xattr name to set | |
160 | * @value - value to set @name to | |
161 | * @size - size of @value | |
162 | * @flags - flags to pass into filesystem operations | |
163 | * | |
164 | * returns the result of the internal setxattr or setsecurity operations. | |
165 | * | |
166 | * This function requires the caller to lock the inode's i_mutex before it | |
167 | * is executed. It also assumes that the caller will make the appropriate | |
168 | * permission checks. | |
169 | */ | |
170 | int __vfs_setxattr_noperm(struct dentry *dentry, const char *name, | |
171 | const void *value, size_t size, int flags) | |
172 | { | |
173 | struct inode *inode = dentry->d_inode; | |
174 | int error = -EAGAIN; | |
175 | int issec = !strncmp(name, XATTR_SECURITY_PREFIX, | |
176 | XATTR_SECURITY_PREFIX_LEN); | |
177 | ||
178 | if (issec) | |
179 | inode->i_flags &= ~S_NOSEC; | |
180 | if (inode->i_opflags & IOP_XATTR) { | |
181 | error = __vfs_setxattr(dentry, inode, name, value, size, flags); | |
182 | if (!error) { | |
183 | fsnotify_xattr(dentry); | |
184 | security_inode_post_setxattr(dentry, name, value, | |
185 | size, flags); | |
186 | } | |
187 | } else { | |
188 | if (unlikely(is_bad_inode(inode))) | |
189 | return -EIO; | |
190 | } | |
191 | if (error == -EAGAIN) { | |
192 | error = -EOPNOTSUPP; | |
193 | ||
194 | if (issec) { | |
195 | const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; | |
196 | ||
197 | error = security_inode_setsecurity(inode, suffix, value, | |
198 | size, flags); | |
199 | if (!error) | |
200 | fsnotify_xattr(dentry); | |
201 | } | |
202 | } | |
203 | ||
204 | return error; | |
205 | } | |
206 | ||
207 | ||
208 | int | |
209 | vfs_setxattr(struct dentry *dentry, const char *name, const void *value, | |
210 | size_t size, int flags) | |
211 | { | |
212 | struct inode *inode = dentry->d_inode; | |
213 | int error; | |
214 | ||
215 | error = xattr_permission(inode, name, MAY_WRITE); | |
216 | if (error) | |
217 | return error; | |
218 | ||
219 | inode_lock(inode); | |
220 | error = security_inode_setxattr(dentry, name, value, size, flags); | |
221 | if (error) | |
222 | goto out; | |
223 | ||
224 | error = __vfs_setxattr_noperm(dentry, name, value, size, flags); | |
225 | ||
226 | out: | |
227 | inode_unlock(inode); | |
228 | return error; | |
229 | } | |
230 | EXPORT_SYMBOL_GPL(vfs_setxattr); | |
231 | ||
232 | static ssize_t | |
233 | xattr_getsecurity(struct inode *inode, const char *name, void *value, | |
234 | size_t size) | |
235 | { | |
236 | void *buffer = NULL; | |
237 | ssize_t len; | |
238 | ||
239 | if (!value || !size) { | |
240 | len = security_inode_getsecurity(inode, name, &buffer, false); | |
241 | goto out_noalloc; | |
242 | } | |
243 | ||
244 | len = security_inode_getsecurity(inode, name, &buffer, true); | |
245 | if (len < 0) | |
246 | return len; | |
247 | if (size < len) { | |
248 | len = -ERANGE; | |
249 | goto out; | |
250 | } | |
251 | memcpy(value, buffer, len); | |
252 | out: | |
253 | kfree(buffer); | |
254 | out_noalloc: | |
255 | return len; | |
256 | } | |
257 | ||
258 | /* | |
259 | * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr | |
260 | * | |
261 | * Allocate memory, if not already allocated, or re-allocate correct size, | |
262 | * before retrieving the extended attribute. | |
263 | * | |
264 | * Returns the result of alloc, if failed, or the getxattr operation. | |
265 | */ | |
266 | ssize_t | |
267 | vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value, | |
268 | size_t xattr_size, gfp_t flags) | |
269 | { | |
270 | const struct xattr_handler *handler; | |
271 | struct inode *inode = dentry->d_inode; | |
272 | char *value = *xattr_value; | |
273 | int error; | |
274 | ||
275 | error = xattr_permission(inode, name, MAY_READ); | |
276 | if (error) | |
277 | return error; | |
278 | ||
279 | handler = xattr_resolve_name(inode, &name); | |
280 | if (IS_ERR(handler)) | |
281 | return PTR_ERR(handler); | |
282 | if (!handler->get) | |
283 | return -EOPNOTSUPP; | |
284 | error = handler->get(handler, dentry, inode, name, NULL, 0); | |
285 | if (error < 0) | |
286 | return error; | |
287 | ||
288 | if (!value || (error > xattr_size)) { | |
289 | value = krealloc(*xattr_value, error + 1, flags); | |
290 | if (!value) | |
291 | return -ENOMEM; | |
292 | memset(value, 0, error + 1); | |
293 | } | |
294 | ||
295 | error = handler->get(handler, dentry, inode, name, value, error); | |
296 | *xattr_value = value; | |
297 | return error; | |
298 | } | |
299 | ||
300 | ssize_t | |
301 | __vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name, | |
302 | void *value, size_t size) | |
303 | { | |
304 | const struct xattr_handler *handler; | |
305 | ||
306 | handler = xattr_resolve_name(inode, &name); | |
307 | if (IS_ERR(handler)) | |
308 | return PTR_ERR(handler); | |
309 | if (!handler->get) | |
310 | return -EOPNOTSUPP; | |
311 | return handler->get(handler, dentry, inode, name, value, size); | |
312 | } | |
313 | EXPORT_SYMBOL(__vfs_getxattr); | |
314 | ||
315 | ssize_t | |
316 | vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size) | |
317 | { | |
318 | struct inode *inode = dentry->d_inode; | |
319 | int error; | |
320 | ||
321 | error = xattr_permission(inode, name, MAY_READ); | |
322 | if (error) | |
323 | return error; | |
324 | ||
325 | error = security_inode_getxattr(dentry, name); | |
326 | if (error) | |
327 | return error; | |
328 | ||
329 | if (!strncmp(name, XATTR_SECURITY_PREFIX, | |
330 | XATTR_SECURITY_PREFIX_LEN)) { | |
331 | const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; | |
332 | int ret = xattr_getsecurity(inode, suffix, value, size); | |
333 | /* | |
334 | * Only overwrite the return value if a security module | |
335 | * is actually active. | |
336 | */ | |
337 | if (ret == -EOPNOTSUPP) | |
338 | goto nolsm; | |
339 | return ret; | |
340 | } | |
341 | nolsm: | |
342 | return __vfs_getxattr(dentry, inode, name, value, size); | |
343 | } | |
344 | EXPORT_SYMBOL_GPL(vfs_getxattr); | |
345 | ||
346 | ssize_t | |
347 | vfs_listxattr(struct dentry *dentry, char *list, size_t size) | |
348 | { | |
349 | struct inode *inode = d_inode(dentry); | |
350 | ssize_t error; | |
351 | ||
352 | error = security_inode_listxattr(dentry); | |
353 | if (error) | |
354 | return error; | |
355 | if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) { | |
356 | error = inode->i_op->listxattr(dentry, list, size); | |
357 | } else { | |
358 | error = security_inode_listsecurity(inode, list, size); | |
359 | if (size && error > size) | |
360 | error = -ERANGE; | |
361 | } | |
362 | return error; | |
363 | } | |
364 | EXPORT_SYMBOL_GPL(vfs_listxattr); | |
365 | ||
366 | int | |
367 | __vfs_removexattr(struct dentry *dentry, const char *name) | |
368 | { | |
369 | struct inode *inode = d_inode(dentry); | |
370 | const struct xattr_handler *handler; | |
371 | ||
372 | handler = xattr_resolve_name(inode, &name); | |
373 | if (IS_ERR(handler)) | |
374 | return PTR_ERR(handler); | |
375 | if (!handler->set) | |
376 | return -EOPNOTSUPP; | |
377 | return handler->set(handler, dentry, inode, name, NULL, 0, XATTR_REPLACE); | |
378 | } | |
379 | EXPORT_SYMBOL(__vfs_removexattr); | |
380 | ||
381 | int | |
382 | vfs_removexattr(struct dentry *dentry, const char *name) | |
383 | { | |
384 | struct inode *inode = dentry->d_inode; | |
385 | int error; | |
386 | ||
387 | error = xattr_permission(inode, name, MAY_WRITE); | |
388 | if (error) | |
389 | return error; | |
390 | ||
391 | inode_lock(inode); | |
392 | error = security_inode_removexattr(dentry, name); | |
393 | if (error) | |
394 | goto out; | |
395 | ||
396 | error = __vfs_removexattr(dentry, name); | |
397 | ||
398 | if (!error) { | |
399 | fsnotify_xattr(dentry); | |
400 | evm_inode_post_removexattr(dentry, name); | |
401 | } | |
402 | ||
403 | out: | |
404 | inode_unlock(inode); | |
405 | return error; | |
406 | } | |
407 | EXPORT_SYMBOL_GPL(vfs_removexattr); | |
408 | ||
409 | ||
410 | /* | |
411 | * Extended attribute SET operations | |
412 | */ | |
413 | static long | |
414 | setxattr(struct dentry *d, const char __user *name, const void __user *value, | |
415 | size_t size, int flags) | |
416 | { | |
417 | int error; | |
418 | void *kvalue = NULL; | |
419 | char kname[XATTR_NAME_MAX + 1]; | |
420 | ||
421 | if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) | |
422 | return -EINVAL; | |
423 | ||
424 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
425 | if (error == 0 || error == sizeof(kname)) | |
426 | error = -ERANGE; | |
427 | if (error < 0) | |
428 | return error; | |
429 | ||
430 | if (size) { | |
431 | if (size > XATTR_SIZE_MAX) | |
432 | return -E2BIG; | |
433 | kvalue = kvmalloc(size, GFP_KERNEL); | |
434 | if (!kvalue) | |
435 | return -ENOMEM; | |
436 | if (copy_from_user(kvalue, value, size)) { | |
437 | error = -EFAULT; | |
438 | goto out; | |
439 | } | |
440 | if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) || | |
441 | (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)) | |
442 | posix_acl_fix_xattr_from_user(kvalue, size); | |
443 | else if (strcmp(kname, XATTR_NAME_CAPS) == 0) { | |
444 | error = cap_convert_nscap(d, &kvalue, size); | |
445 | if (error < 0) | |
446 | goto out; | |
447 | size = error; | |
448 | } | |
449 | } | |
450 | ||
451 | error = vfs_setxattr(d, kname, kvalue, size, flags); | |
452 | out: | |
453 | kvfree(kvalue); | |
454 | ||
455 | return error; | |
456 | } | |
457 | ||
458 | static int path_setxattr(const char __user *pathname, | |
459 | const char __user *name, const void __user *value, | |
460 | size_t size, int flags, unsigned int lookup_flags) | |
461 | { | |
462 | struct path path; | |
463 | int error; | |
464 | retry: | |
465 | error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); | |
466 | if (error) | |
467 | return error; | |
468 | error = mnt_want_write(path.mnt); | |
469 | if (!error) { | |
470 | error = setxattr(path.dentry, name, value, size, flags); | |
471 | mnt_drop_write(path.mnt); | |
472 | } | |
473 | path_put(&path); | |
474 | if (retry_estale(error, lookup_flags)) { | |
475 | lookup_flags |= LOOKUP_REVAL; | |
476 | goto retry; | |
477 | } | |
478 | return error; | |
479 | } | |
480 | ||
481 | SYSCALL_DEFINE5(setxattr, const char __user *, pathname, | |
482 | const char __user *, name, const void __user *, value, | |
483 | size_t, size, int, flags) | |
484 | { | |
485 | return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW); | |
486 | } | |
487 | ||
488 | SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname, | |
489 | const char __user *, name, const void __user *, value, | |
490 | size_t, size, int, flags) | |
491 | { | |
492 | return path_setxattr(pathname, name, value, size, flags, 0); | |
493 | } | |
494 | ||
495 | SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name, | |
496 | const void __user *,value, size_t, size, int, flags) | |
497 | { | |
498 | struct fd f = fdget(fd); | |
499 | int error = -EBADF; | |
500 | ||
501 | if (!f.file) | |
502 | return error; | |
503 | audit_file(f.file); | |
504 | error = mnt_want_write_file(f.file); | |
505 | if (!error) { | |
506 | error = setxattr(f.file->f_path.dentry, name, value, size, flags); | |
507 | mnt_drop_write_file(f.file); | |
508 | } | |
509 | fdput(f); | |
510 | return error; | |
511 | } | |
512 | ||
513 | /* | |
514 | * Extended attribute GET operations | |
515 | */ | |
516 | static ssize_t | |
517 | getxattr(struct dentry *d, const char __user *name, void __user *value, | |
518 | size_t size) | |
519 | { | |
520 | ssize_t error; | |
521 | void *kvalue = NULL; | |
522 | char kname[XATTR_NAME_MAX + 1]; | |
523 | ||
524 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
525 | if (error == 0 || error == sizeof(kname)) | |
526 | error = -ERANGE; | |
527 | if (error < 0) | |
528 | return error; | |
529 | ||
530 | if (size) { | |
531 | if (size > XATTR_SIZE_MAX) | |
532 | size = XATTR_SIZE_MAX; | |
533 | kvalue = kvzalloc(size, GFP_KERNEL); | |
534 | if (!kvalue) | |
535 | return -ENOMEM; | |
536 | } | |
537 | ||
538 | error = vfs_getxattr(d, kname, kvalue, size); | |
539 | if (error > 0) { | |
540 | if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) || | |
541 | (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)) | |
542 | posix_acl_fix_xattr_to_user(kvalue, error); | |
543 | if (size && copy_to_user(value, kvalue, error)) | |
544 | error = -EFAULT; | |
545 | } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { | |
546 | /* The file system tried to returned a value bigger | |
547 | than XATTR_SIZE_MAX bytes. Not possible. */ | |
548 | error = -E2BIG; | |
549 | } | |
550 | ||
551 | kvfree(kvalue); | |
552 | ||
553 | return error; | |
554 | } | |
555 | ||
556 | static ssize_t path_getxattr(const char __user *pathname, | |
557 | const char __user *name, void __user *value, | |
558 | size_t size, unsigned int lookup_flags) | |
559 | { | |
560 | struct path path; | |
561 | ssize_t error; | |
562 | retry: | |
563 | error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); | |
564 | if (error) | |
565 | return error; | |
566 | error = getxattr(path.dentry, name, value, size); | |
567 | path_put(&path); | |
568 | if (retry_estale(error, lookup_flags)) { | |
569 | lookup_flags |= LOOKUP_REVAL; | |
570 | goto retry; | |
571 | } | |
572 | return error; | |
573 | } | |
574 | ||
575 | SYSCALL_DEFINE4(getxattr, const char __user *, pathname, | |
576 | const char __user *, name, void __user *, value, size_t, size) | |
577 | { | |
578 | return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW); | |
579 | } | |
580 | ||
581 | SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname, | |
582 | const char __user *, name, void __user *, value, size_t, size) | |
583 | { | |
584 | return path_getxattr(pathname, name, value, size, 0); | |
585 | } | |
586 | ||
587 | SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name, | |
588 | void __user *, value, size_t, size) | |
589 | { | |
590 | struct fd f = fdget(fd); | |
591 | ssize_t error = -EBADF; | |
592 | ||
593 | if (!f.file) | |
594 | return error; | |
595 | audit_file(f.file); | |
596 | error = getxattr(f.file->f_path.dentry, name, value, size); | |
597 | fdput(f); | |
598 | return error; | |
599 | } | |
600 | ||
601 | /* | |
602 | * Extended attribute LIST operations | |
603 | */ | |
604 | static ssize_t | |
605 | listxattr(struct dentry *d, char __user *list, size_t size) | |
606 | { | |
607 | ssize_t error; | |
608 | char *klist = NULL; | |
609 | ||
610 | if (size) { | |
611 | if (size > XATTR_LIST_MAX) | |
612 | size = XATTR_LIST_MAX; | |
613 | klist = kvmalloc(size, GFP_KERNEL); | |
614 | if (!klist) | |
615 | return -ENOMEM; | |
616 | } | |
617 | ||
618 | error = vfs_listxattr(d, klist, size); | |
619 | if (error > 0) { | |
620 | if (size && copy_to_user(list, klist, error)) | |
621 | error = -EFAULT; | |
622 | } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { | |
623 | /* The file system tried to returned a list bigger | |
624 | than XATTR_LIST_MAX bytes. Not possible. */ | |
625 | error = -E2BIG; | |
626 | } | |
627 | ||
628 | kvfree(klist); | |
629 | ||
630 | return error; | |
631 | } | |
632 | ||
633 | static ssize_t path_listxattr(const char __user *pathname, char __user *list, | |
634 | size_t size, unsigned int lookup_flags) | |
635 | { | |
636 | struct path path; | |
637 | ssize_t error; | |
638 | retry: | |
639 | error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); | |
640 | if (error) | |
641 | return error; | |
642 | error = listxattr(path.dentry, list, size); | |
643 | path_put(&path); | |
644 | if (retry_estale(error, lookup_flags)) { | |
645 | lookup_flags |= LOOKUP_REVAL; | |
646 | goto retry; | |
647 | } | |
648 | return error; | |
649 | } | |
650 | ||
651 | SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list, | |
652 | size_t, size) | |
653 | { | |
654 | return path_listxattr(pathname, list, size, LOOKUP_FOLLOW); | |
655 | } | |
656 | ||
657 | SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list, | |
658 | size_t, size) | |
659 | { | |
660 | return path_listxattr(pathname, list, size, 0); | |
661 | } | |
662 | ||
663 | SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size) | |
664 | { | |
665 | struct fd f = fdget(fd); | |
666 | ssize_t error = -EBADF; | |
667 | ||
668 | if (!f.file) | |
669 | return error; | |
670 | audit_file(f.file); | |
671 | error = listxattr(f.file->f_path.dentry, list, size); | |
672 | fdput(f); | |
673 | return error; | |
674 | } | |
675 | ||
676 | /* | |
677 | * Extended attribute REMOVE operations | |
678 | */ | |
679 | static long | |
680 | removexattr(struct dentry *d, const char __user *name) | |
681 | { | |
682 | int error; | |
683 | char kname[XATTR_NAME_MAX + 1]; | |
684 | ||
685 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
686 | if (error == 0 || error == sizeof(kname)) | |
687 | error = -ERANGE; | |
688 | if (error < 0) | |
689 | return error; | |
690 | ||
691 | return vfs_removexattr(d, kname); | |
692 | } | |
693 | ||
694 | static int path_removexattr(const char __user *pathname, | |
695 | const char __user *name, unsigned int lookup_flags) | |
696 | { | |
697 | struct path path; | |
698 | int error; | |
699 | retry: | |
700 | error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); | |
701 | if (error) | |
702 | return error; | |
703 | error = mnt_want_write(path.mnt); | |
704 | if (!error) { | |
705 | error = removexattr(path.dentry, name); | |
706 | mnt_drop_write(path.mnt); | |
707 | } | |
708 | path_put(&path); | |
709 | if (retry_estale(error, lookup_flags)) { | |
710 | lookup_flags |= LOOKUP_REVAL; | |
711 | goto retry; | |
712 | } | |
713 | return error; | |
714 | } | |
715 | ||
716 | SYSCALL_DEFINE2(removexattr, const char __user *, pathname, | |
717 | const char __user *, name) | |
718 | { | |
719 | return path_removexattr(pathname, name, LOOKUP_FOLLOW); | |
720 | } | |
721 | ||
722 | SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname, | |
723 | const char __user *, name) | |
724 | { | |
725 | return path_removexattr(pathname, name, 0); | |
726 | } | |
727 | ||
728 | SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name) | |
729 | { | |
730 | struct fd f = fdget(fd); | |
731 | int error = -EBADF; | |
732 | ||
733 | if (!f.file) | |
734 | return error; | |
735 | audit_file(f.file); | |
736 | error = mnt_want_write_file(f.file); | |
737 | if (!error) { | |
738 | error = removexattr(f.file->f_path.dentry, name); | |
739 | mnt_drop_write_file(f.file); | |
740 | } | |
741 | fdput(f); | |
742 | return error; | |
743 | } | |
744 | ||
745 | /* | |
746 | * Combine the results of the list() operation from every xattr_handler in the | |
747 | * list. | |
748 | */ | |
749 | ssize_t | |
750 | generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) | |
751 | { | |
752 | const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr; | |
753 | unsigned int size = 0; | |
754 | ||
755 | if (!buffer) { | |
756 | for_each_xattr_handler(handlers, handler) { | |
757 | if (!handler->name || | |
758 | (handler->list && !handler->list(dentry))) | |
759 | continue; | |
760 | size += strlen(handler->name) + 1; | |
761 | } | |
762 | } else { | |
763 | char *buf = buffer; | |
764 | size_t len; | |
765 | ||
766 | for_each_xattr_handler(handlers, handler) { | |
767 | if (!handler->name || | |
768 | (handler->list && !handler->list(dentry))) | |
769 | continue; | |
770 | len = strlen(handler->name); | |
771 | if (len + 1 > buffer_size) | |
772 | return -ERANGE; | |
773 | memcpy(buf, handler->name, len + 1); | |
774 | buf += len + 1; | |
775 | buffer_size -= len + 1; | |
776 | } | |
777 | size = buf - buffer; | |
778 | } | |
779 | return size; | |
780 | } | |
781 | EXPORT_SYMBOL(generic_listxattr); | |
782 | ||
783 | /** | |
784 | * xattr_full_name - Compute full attribute name from suffix | |
785 | * | |
786 | * @handler: handler of the xattr_handler operation | |
787 | * @name: name passed to the xattr_handler operation | |
788 | * | |
789 | * The get and set xattr handler operations are called with the remainder of | |
790 | * the attribute name after skipping the handler's prefix: for example, "foo" | |
791 | * is passed to the get operation of a handler with prefix "user." to get | |
792 | * attribute "user.foo". The full name is still "there" in the name though. | |
793 | * | |
794 | * Note: the list xattr handler operation when called from the vfs is passed a | |
795 | * NULL name; some file systems use this operation internally, with varying | |
796 | * semantics. | |
797 | */ | |
798 | const char *xattr_full_name(const struct xattr_handler *handler, | |
799 | const char *name) | |
800 | { | |
801 | size_t prefix_len = strlen(xattr_prefix(handler)); | |
802 | ||
803 | return name - prefix_len; | |
804 | } | |
805 | EXPORT_SYMBOL(xattr_full_name); | |
806 | ||
807 | /* | |
808 | * Allocate new xattr and copy in the value; but leave the name to callers. | |
809 | */ | |
810 | struct simple_xattr *simple_xattr_alloc(const void *value, size_t size) | |
811 | { | |
812 | struct simple_xattr *new_xattr; | |
813 | size_t len; | |
814 | ||
815 | /* wrap around? */ | |
816 | len = sizeof(*new_xattr) + size; | |
817 | if (len < sizeof(*new_xattr)) | |
818 | return NULL; | |
819 | ||
820 | new_xattr = kmalloc(len, GFP_KERNEL); | |
821 | if (!new_xattr) | |
822 | return NULL; | |
823 | ||
824 | new_xattr->size = size; | |
825 | memcpy(new_xattr->value, value, size); | |
826 | return new_xattr; | |
827 | } | |
828 | ||
829 | /* | |
830 | * xattr GET operation for in-memory/pseudo filesystems | |
831 | */ | |
832 | int simple_xattr_get(struct simple_xattrs *xattrs, const char *name, | |
833 | void *buffer, size_t size) | |
834 | { | |
835 | struct simple_xattr *xattr; | |
836 | int ret = -ENODATA; | |
837 | ||
838 | spin_lock(&xattrs->lock); | |
839 | list_for_each_entry(xattr, &xattrs->head, list) { | |
840 | if (strcmp(name, xattr->name)) | |
841 | continue; | |
842 | ||
843 | ret = xattr->size; | |
844 | if (buffer) { | |
845 | if (size < xattr->size) | |
846 | ret = -ERANGE; | |
847 | else | |
848 | memcpy(buffer, xattr->value, xattr->size); | |
849 | } | |
850 | break; | |
851 | } | |
852 | spin_unlock(&xattrs->lock); | |
853 | return ret; | |
854 | } | |
855 | ||
856 | /** | |
857 | * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems | |
858 | * @xattrs: target simple_xattr list | |
859 | * @name: name of the extended attribute | |
860 | * @value: value of the xattr. If %NULL, will remove the attribute. | |
861 | * @size: size of the new xattr | |
862 | * @flags: %XATTR_{CREATE|REPLACE} | |
863 | * | |
864 | * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails | |
865 | * with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist; | |
866 | * otherwise, fails with -ENODATA. | |
867 | * | |
868 | * Returns 0 on success, -errno on failure. | |
869 | */ | |
870 | int simple_xattr_set(struct simple_xattrs *xattrs, const char *name, | |
871 | const void *value, size_t size, int flags) | |
872 | { | |
873 | struct simple_xattr *xattr; | |
874 | struct simple_xattr *new_xattr = NULL; | |
875 | int err = 0; | |
876 | ||
877 | /* value == NULL means remove */ | |
878 | if (value) { | |
879 | new_xattr = simple_xattr_alloc(value, size); | |
880 | if (!new_xattr) | |
881 | return -ENOMEM; | |
882 | ||
883 | new_xattr->name = kstrdup(name, GFP_KERNEL); | |
884 | if (!new_xattr->name) { | |
885 | kfree(new_xattr); | |
886 | return -ENOMEM; | |
887 | } | |
888 | } | |
889 | ||
890 | spin_lock(&xattrs->lock); | |
891 | list_for_each_entry(xattr, &xattrs->head, list) { | |
892 | if (!strcmp(name, xattr->name)) { | |
893 | if (flags & XATTR_CREATE) { | |
894 | xattr = new_xattr; | |
895 | err = -EEXIST; | |
896 | } else if (new_xattr) { | |
897 | list_replace(&xattr->list, &new_xattr->list); | |
898 | } else { | |
899 | list_del(&xattr->list); | |
900 | } | |
901 | goto out; | |
902 | } | |
903 | } | |
904 | if (flags & XATTR_REPLACE) { | |
905 | xattr = new_xattr; | |
906 | err = -ENODATA; | |
907 | } else { | |
908 | list_add(&new_xattr->list, &xattrs->head); | |
909 | xattr = NULL; | |
910 | } | |
911 | out: | |
912 | spin_unlock(&xattrs->lock); | |
913 | if (xattr) { | |
914 | kfree(xattr->name); | |
915 | kfree(xattr); | |
916 | } | |
917 | return err; | |
918 | ||
919 | } | |
920 | ||
921 | static bool xattr_is_trusted(const char *name) | |
922 | { | |
923 | return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN); | |
924 | } | |
925 | ||
926 | static int xattr_list_one(char **buffer, ssize_t *remaining_size, | |
927 | const char *name) | |
928 | { | |
929 | size_t len = strlen(name) + 1; | |
930 | if (*buffer) { | |
931 | if (*remaining_size < len) | |
932 | return -ERANGE; | |
933 | memcpy(*buffer, name, len); | |
934 | *buffer += len; | |
935 | } | |
936 | *remaining_size -= len; | |
937 | return 0; | |
938 | } | |
939 | ||
940 | /* | |
941 | * xattr LIST operation for in-memory/pseudo filesystems | |
942 | */ | |
943 | ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, | |
944 | char *buffer, size_t size) | |
945 | { | |
946 | bool trusted = capable(CAP_SYS_ADMIN); | |
947 | struct simple_xattr *xattr; | |
948 | ssize_t remaining_size = size; | |
949 | int err = 0; | |
950 | ||
951 | #ifdef CONFIG_FS_POSIX_ACL | |
952 | if (IS_POSIXACL(inode)) { | |
953 | if (inode->i_acl) { | |
954 | err = xattr_list_one(&buffer, &remaining_size, | |
955 | XATTR_NAME_POSIX_ACL_ACCESS); | |
956 | if (err) | |
957 | return err; | |
958 | } | |
959 | if (inode->i_default_acl) { | |
960 | err = xattr_list_one(&buffer, &remaining_size, | |
961 | XATTR_NAME_POSIX_ACL_DEFAULT); | |
962 | if (err) | |
963 | return err; | |
964 | } | |
965 | } | |
966 | #endif | |
967 | ||
968 | spin_lock(&xattrs->lock); | |
969 | list_for_each_entry(xattr, &xattrs->head, list) { | |
970 | /* skip "trusted." attributes for unprivileged callers */ | |
971 | if (!trusted && xattr_is_trusted(xattr->name)) | |
972 | continue; | |
973 | ||
974 | err = xattr_list_one(&buffer, &remaining_size, xattr->name); | |
975 | if (err) | |
976 | break; | |
977 | } | |
978 | spin_unlock(&xattrs->lock); | |
979 | ||
980 | return err ? err : size - remaining_size; | |
981 | } | |
982 | ||
983 | /* | |
984 | * Adds an extended attribute to the list | |
985 | */ | |
986 | void simple_xattr_list_add(struct simple_xattrs *xattrs, | |
987 | struct simple_xattr *new_xattr) | |
988 | { | |
989 | spin_lock(&xattrs->lock); | |
990 | list_add(&new_xattr->list, &xattrs->head); | |
991 | spin_unlock(&xattrs->lock); | |
992 | } |