Line data Source code
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 0 : while (*a_prefix && *a == *a_prefix) {
32 0 : a++;
33 0 : a_prefix++;
34 : }
35 0 : 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 0 : xattr_resolve_name(struct inode *inode, const char **name)
55 : {
56 0 : const struct xattr_handler **handlers = inode->i_sb->s_xattr;
57 : const struct xattr_handler *handler;
58 :
59 0 : if (!(inode->i_opflags & IOP_XATTR)) {
60 0 : if (unlikely(is_bad_inode(inode)))
61 : return ERR_PTR(-EIO);
62 0 : return ERR_PTR(-EOPNOTSUPP);
63 : }
64 0 : for_each_xattr_handler(handlers, handler) {
65 : const char *n;
66 :
67 0 : n = strcmp_prefix(*name, xattr_prefix(handler));
68 0 : if (n) {
69 0 : if (!handler->prefix ^ !*n) {
70 0 : if (*n)
71 0 : continue;
72 : return ERR_PTR(-EINVAL);
73 : }
74 0 : *name = n;
75 0 : 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 0 : xattr_permission(struct user_namespace *mnt_userns, struct inode *inode,
87 : const char *name, int mask)
88 : {
89 : /*
90 : * We can never set or remove an extended attribute on a read-only
91 : * filesystem or on an immutable / append-only inode.
92 : */
93 0 : if (mask & MAY_WRITE) {
94 0 : if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
95 : return -EPERM;
96 : /*
97 : * Updating an xattr will likely cause i_uid and i_gid
98 : * to be writen back improperly if their true value is
99 : * unknown to the vfs.
100 : */
101 0 : if (HAS_UNMAPPED_ID(mnt_userns, inode))
102 : return -EPERM;
103 : }
104 :
105 : /*
106 : * No restriction for security.* and system.* from the VFS. Decision
107 : * on these is left to the underlying filesystem / security module.
108 : */
109 0 : if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
110 0 : !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
111 : return 0;
112 :
113 : /*
114 : * The trusted.* namespace can only be accessed by privileged users.
115 : */
116 0 : if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
117 0 : if (!capable(CAP_SYS_ADMIN))
118 0 : return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
119 : return 0;
120 : }
121 :
122 : /*
123 : * In the user.* namespace, only regular files and directories can have
124 : * extended attributes. For sticky directories, only the owner and
125 : * privileged users can write attributes.
126 : */
127 0 : if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
128 0 : if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
129 0 : return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
130 0 : if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
131 0 : (mask & MAY_WRITE) &&
132 0 : !inode_owner_or_capable(mnt_userns, inode))
133 : return -EPERM;
134 : }
135 :
136 0 : return inode_permission(mnt_userns, inode, mask);
137 : }
138 :
139 : /*
140 : * Look for any handler that deals with the specified namespace.
141 : */
142 : int
143 0 : xattr_supported_namespace(struct inode *inode, const char *prefix)
144 : {
145 0 : const struct xattr_handler **handlers = inode->i_sb->s_xattr;
146 : const struct xattr_handler *handler;
147 : size_t preflen;
148 :
149 0 : if (!(inode->i_opflags & IOP_XATTR)) {
150 0 : if (unlikely(is_bad_inode(inode)))
151 : return -EIO;
152 0 : return -EOPNOTSUPP;
153 : }
154 :
155 0 : preflen = strlen(prefix);
156 :
157 0 : for_each_xattr_handler(handlers, handler) {
158 0 : if (!strncmp(xattr_prefix(handler), prefix, preflen))
159 : return 0;
160 : }
161 :
162 : return -EOPNOTSUPP;
163 : }
164 : EXPORT_SYMBOL(xattr_supported_namespace);
165 :
166 : int
167 0 : __vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
168 : struct inode *inode, const char *name, const void *value,
169 : size_t size, int flags)
170 : {
171 : const struct xattr_handler *handler;
172 :
173 0 : handler = xattr_resolve_name(inode, &name);
174 0 : if (IS_ERR(handler))
175 0 : return PTR_ERR(handler);
176 0 : if (!handler->set)
177 : return -EOPNOTSUPP;
178 0 : if (size == 0)
179 0 : value = ""; /* empty EA, do not remove */
180 0 : return handler->set(handler, mnt_userns, dentry, inode, name, value,
181 : size, flags);
182 : }
183 : EXPORT_SYMBOL(__vfs_setxattr);
184 :
185 : /**
186 : * __vfs_setxattr_noperm - perform setxattr operation without performing
187 : * permission checks.
188 : *
189 : * @mnt_userns: user namespace of the mount the inode was found from
190 : * @dentry: object to perform setxattr on
191 : * @name: xattr name to set
192 : * @value: value to set @name to
193 : * @size: size of @value
194 : * @flags: flags to pass into filesystem operations
195 : *
196 : * returns the result of the internal setxattr or setsecurity operations.
197 : *
198 : * This function requires the caller to lock the inode's i_mutex before it
199 : * is executed. It also assumes that the caller will make the appropriate
200 : * permission checks.
201 : */
202 0 : int __vfs_setxattr_noperm(struct user_namespace *mnt_userns,
203 : struct dentry *dentry, const char *name,
204 : const void *value, size_t size, int flags)
205 : {
206 0 : struct inode *inode = dentry->d_inode;
207 0 : int error = -EAGAIN;
208 0 : int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
209 : XATTR_SECURITY_PREFIX_LEN);
210 :
211 0 : if (issec)
212 0 : inode->i_flags &= ~S_NOSEC;
213 0 : if (inode->i_opflags & IOP_XATTR) {
214 0 : error = __vfs_setxattr(mnt_userns, dentry, inode, name, value,
215 : size, flags);
216 0 : if (!error) {
217 : fsnotify_xattr(dentry);
218 : security_inode_post_setxattr(dentry, name, value,
219 : size, flags);
220 : }
221 : } else {
222 0 : if (unlikely(is_bad_inode(inode)))
223 : return -EIO;
224 : }
225 0 : if (error == -EAGAIN) {
226 0 : error = -EOPNOTSUPP;
227 :
228 : if (issec) {
229 : const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
230 :
231 : error = security_inode_setsecurity(inode, suffix, value,
232 : size, flags);
233 : if (!error)
234 : fsnotify_xattr(dentry);
235 : }
236 : }
237 :
238 : return error;
239 : }
240 :
241 : /**
242 : * __vfs_setxattr_locked - set an extended attribute while holding the inode
243 : * lock
244 : *
245 : * @mnt_userns: user namespace of the mount of the target inode
246 : * @dentry: object to perform setxattr on
247 : * @name: xattr name to set
248 : * @value: value to set @name to
249 : * @size: size of @value
250 : * @flags: flags to pass into filesystem operations
251 : * @delegated_inode: on return, will contain an inode pointer that
252 : * a delegation was broken on, NULL if none.
253 : */
254 : int
255 0 : __vfs_setxattr_locked(struct user_namespace *mnt_userns, struct dentry *dentry,
256 : const char *name, const void *value, size_t size,
257 : int flags, struct inode **delegated_inode)
258 : {
259 0 : struct inode *inode = dentry->d_inode;
260 : int error;
261 :
262 0 : error = xattr_permission(mnt_userns, inode, name, MAY_WRITE);
263 0 : if (error)
264 : return error;
265 :
266 0 : error = security_inode_setxattr(mnt_userns, dentry, name, value, size,
267 : flags);
268 0 : if (error)
269 : goto out;
270 :
271 0 : error = try_break_deleg(inode, delegated_inode);
272 0 : if (error)
273 : goto out;
274 :
275 0 : error = __vfs_setxattr_noperm(mnt_userns, dentry, name, value,
276 : size, flags);
277 :
278 : out:
279 : return error;
280 : }
281 : EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
282 :
283 : int
284 0 : vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
285 : const char *name, const void *value, size_t size, int flags)
286 : {
287 0 : struct inode *inode = dentry->d_inode;
288 0 : struct inode *delegated_inode = NULL;
289 0 : const void *orig_value = value;
290 : int error;
291 :
292 0 : if (size && strcmp(name, XATTR_NAME_CAPS) == 0) {
293 0 : error = cap_convert_nscap(mnt_userns, dentry, &value, size);
294 0 : if (error < 0)
295 : return error;
296 0 : size = error;
297 : }
298 :
299 : retry_deleg:
300 0 : inode_lock(inode);
301 0 : error = __vfs_setxattr_locked(mnt_userns, dentry, name, value, size,
302 : flags, &delegated_inode);
303 0 : inode_unlock(inode);
304 :
305 0 : if (delegated_inode) {
306 0 : error = break_deleg_wait(&delegated_inode);
307 0 : if (!error)
308 : goto retry_deleg;
309 : }
310 0 : if (value != orig_value)
311 0 : kfree(value);
312 :
313 : return error;
314 : }
315 : EXPORT_SYMBOL_GPL(vfs_setxattr);
316 :
317 : static ssize_t
318 0 : xattr_getsecurity(struct user_namespace *mnt_userns, struct inode *inode,
319 : const char *name, void *value, size_t size)
320 : {
321 0 : void *buffer = NULL;
322 : ssize_t len;
323 :
324 0 : if (!value || !size) {
325 0 : len = security_inode_getsecurity(mnt_userns, inode, name,
326 : &buffer, false);
327 0 : goto out_noalloc;
328 : }
329 :
330 0 : len = security_inode_getsecurity(mnt_userns, inode, name, &buffer,
331 : true);
332 0 : if (len < 0)
333 : return len;
334 0 : if (size < len) {
335 : len = -ERANGE;
336 : goto out;
337 : }
338 0 : memcpy(value, buffer, len);
339 : out:
340 0 : kfree(buffer);
341 : out_noalloc:
342 : return len;
343 : }
344 :
345 : /*
346 : * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
347 : *
348 : * Allocate memory, if not already allocated, or re-allocate correct size,
349 : * before retrieving the extended attribute.
350 : *
351 : * Returns the result of alloc, if failed, or the getxattr operation.
352 : */
353 : ssize_t
354 0 : vfs_getxattr_alloc(struct user_namespace *mnt_userns, struct dentry *dentry,
355 : const char *name, char **xattr_value, size_t xattr_size,
356 : gfp_t flags)
357 : {
358 : const struct xattr_handler *handler;
359 0 : struct inode *inode = dentry->d_inode;
360 0 : char *value = *xattr_value;
361 : int error;
362 :
363 0 : error = xattr_permission(mnt_userns, inode, name, MAY_READ);
364 0 : if (error)
365 0 : return error;
366 :
367 0 : handler = xattr_resolve_name(inode, &name);
368 0 : if (IS_ERR(handler))
369 0 : return PTR_ERR(handler);
370 0 : if (!handler->get)
371 : return -EOPNOTSUPP;
372 0 : error = handler->get(handler, dentry, inode, name, NULL, 0);
373 0 : if (error < 0)
374 0 : return error;
375 :
376 0 : if (!value || (error > xattr_size)) {
377 0 : value = krealloc(*xattr_value, error + 1, flags);
378 0 : if (!value)
379 : return -ENOMEM;
380 0 : memset(value, 0, error + 1);
381 : }
382 :
383 0 : error = handler->get(handler, dentry, inode, name, value, error);
384 0 : *xattr_value = value;
385 0 : return error;
386 : }
387 :
388 : ssize_t
389 0 : __vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
390 : void *value, size_t size)
391 : {
392 : const struct xattr_handler *handler;
393 :
394 0 : handler = xattr_resolve_name(inode, &name);
395 0 : if (IS_ERR(handler))
396 0 : return PTR_ERR(handler);
397 0 : if (!handler->get)
398 : return -EOPNOTSUPP;
399 0 : return handler->get(handler, dentry, inode, name, value, size);
400 : }
401 : EXPORT_SYMBOL(__vfs_getxattr);
402 :
403 : ssize_t
404 0 : vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
405 : const char *name, void *value, size_t size)
406 : {
407 0 : struct inode *inode = dentry->d_inode;
408 : int error;
409 :
410 0 : error = xattr_permission(mnt_userns, inode, name, MAY_READ);
411 0 : if (error)
412 0 : return error;
413 :
414 0 : error = security_inode_getxattr(dentry, name);
415 : if (error)
416 : return error;
417 :
418 0 : if (!strncmp(name, XATTR_SECURITY_PREFIX,
419 : XATTR_SECURITY_PREFIX_LEN)) {
420 0 : const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
421 0 : int ret = xattr_getsecurity(mnt_userns, inode, suffix, value,
422 : size);
423 : /*
424 : * Only overwrite the return value if a security module
425 : * is actually active.
426 : */
427 0 : if (ret == -EOPNOTSUPP)
428 : goto nolsm;
429 0 : return ret;
430 : }
431 : nolsm:
432 0 : return __vfs_getxattr(dentry, inode, name, value, size);
433 : }
434 : EXPORT_SYMBOL_GPL(vfs_getxattr);
435 :
436 : ssize_t
437 0 : vfs_listxattr(struct dentry *dentry, char *list, size_t size)
438 : {
439 0 : struct inode *inode = d_inode(dentry);
440 : ssize_t error;
441 :
442 0 : error = security_inode_listxattr(dentry);
443 : if (error)
444 : return error;
445 0 : if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) {
446 0 : error = inode->i_op->listxattr(dentry, list, size);
447 : } else {
448 : error = security_inode_listsecurity(inode, list, size);
449 : if (size && error > size)
450 : error = -ERANGE;
451 : }
452 : return error;
453 : }
454 : EXPORT_SYMBOL_GPL(vfs_listxattr);
455 :
456 : int
457 0 : __vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
458 : const char *name)
459 : {
460 0 : struct inode *inode = d_inode(dentry);
461 : const struct xattr_handler *handler;
462 :
463 0 : handler = xattr_resolve_name(inode, &name);
464 0 : if (IS_ERR(handler))
465 0 : return PTR_ERR(handler);
466 0 : if (!handler->set)
467 : return -EOPNOTSUPP;
468 0 : return handler->set(handler, mnt_userns, dentry, inode, name, NULL, 0,
469 : XATTR_REPLACE);
470 : }
471 : EXPORT_SYMBOL(__vfs_removexattr);
472 :
473 : /**
474 : * __vfs_removexattr_locked - set an extended attribute while holding the inode
475 : * lock
476 : *
477 : * @mnt_userns: user namespace of the mount of the target inode
478 : * @dentry: object to perform setxattr on
479 : * @name: name of xattr to remove
480 : * @delegated_inode: on return, will contain an inode pointer that
481 : * a delegation was broken on, NULL if none.
482 : */
483 : int
484 0 : __vfs_removexattr_locked(struct user_namespace *mnt_userns,
485 : struct dentry *dentry, const char *name,
486 : struct inode **delegated_inode)
487 : {
488 0 : struct inode *inode = dentry->d_inode;
489 : int error;
490 :
491 0 : error = xattr_permission(mnt_userns, inode, name, MAY_WRITE);
492 0 : if (error)
493 : return error;
494 :
495 0 : error = security_inode_removexattr(mnt_userns, dentry, name);
496 0 : if (error)
497 : goto out;
498 :
499 0 : error = try_break_deleg(inode, delegated_inode);
500 0 : if (error)
501 : goto out;
502 :
503 0 : error = __vfs_removexattr(mnt_userns, dentry, name);
504 :
505 0 : if (!error) {
506 : fsnotify_xattr(dentry);
507 : evm_inode_post_removexattr(dentry, name);
508 : }
509 :
510 : out:
511 : return error;
512 : }
513 : EXPORT_SYMBOL_GPL(__vfs_removexattr_locked);
514 :
515 : int
516 0 : vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
517 : const char *name)
518 : {
519 0 : struct inode *inode = dentry->d_inode;
520 0 : struct inode *delegated_inode = NULL;
521 : int error;
522 :
523 : retry_deleg:
524 0 : inode_lock(inode);
525 0 : error = __vfs_removexattr_locked(mnt_userns, dentry,
526 : name, &delegated_inode);
527 0 : inode_unlock(inode);
528 :
529 0 : if (delegated_inode) {
530 0 : error = break_deleg_wait(&delegated_inode);
531 0 : if (!error)
532 : goto retry_deleg;
533 : }
534 :
535 0 : return error;
536 : }
537 : EXPORT_SYMBOL_GPL(vfs_removexattr);
538 :
539 : /*
540 : * Extended attribute SET operations
541 : */
542 : static long
543 0 : setxattr(struct user_namespace *mnt_userns, struct dentry *d,
544 : const char __user *name, const void __user *value, size_t size,
545 : int flags)
546 : {
547 : int error;
548 0 : void *kvalue = NULL;
549 : char kname[XATTR_NAME_MAX + 1];
550 :
551 0 : if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
552 : return -EINVAL;
553 :
554 0 : error = strncpy_from_user(kname, name, sizeof(kname));
555 0 : if (error == 0 || error == sizeof(kname))
556 0 : error = -ERANGE;
557 0 : if (error < 0)
558 0 : return error;
559 :
560 0 : if (size) {
561 0 : if (size > XATTR_SIZE_MAX)
562 : return -E2BIG;
563 0 : kvalue = kvmalloc(size, GFP_KERNEL);
564 0 : if (!kvalue)
565 : return -ENOMEM;
566 0 : if (copy_from_user(kvalue, value, size)) {
567 : error = -EFAULT;
568 : goto out;
569 : }
570 0 : if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
571 0 : (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
572 0 : posix_acl_fix_xattr_from_user(mnt_userns, d_inode(d),
573 : kvalue, size);
574 : }
575 :
576 0 : error = vfs_setxattr(mnt_userns, d, kname, kvalue, size, flags);
577 : out:
578 0 : kvfree(kvalue);
579 :
580 0 : return error;
581 : }
582 :
583 0 : static int path_setxattr(const char __user *pathname,
584 : const char __user *name, const void __user *value,
585 : size_t size, int flags, unsigned int lookup_flags)
586 : {
587 : struct path path;
588 : int error;
589 :
590 : retry:
591 0 : error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
592 0 : if (error)
593 : return error;
594 0 : error = mnt_want_write(path.mnt);
595 0 : if (!error) {
596 0 : error = setxattr(mnt_user_ns(path.mnt), path.dentry, name,
597 : value, size, flags);
598 0 : mnt_drop_write(path.mnt);
599 : }
600 0 : path_put(&path);
601 0 : if (retry_estale(error, lookup_flags)) {
602 0 : lookup_flags |= LOOKUP_REVAL;
603 0 : goto retry;
604 : }
605 : return error;
606 : }
607 :
608 0 : SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
609 : const char __user *, name, const void __user *, value,
610 : size_t, size, int, flags)
611 : {
612 0 : return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW);
613 : }
614 :
615 0 : SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
616 : const char __user *, name, const void __user *, value,
617 : size_t, size, int, flags)
618 : {
619 0 : return path_setxattr(pathname, name, value, size, flags, 0);
620 : }
621 :
622 0 : SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
623 : const void __user *,value, size_t, size, int, flags)
624 : {
625 0 : struct fd f = fdget(fd);
626 0 : int error = -EBADF;
627 :
628 0 : if (!f.file)
629 : return error;
630 0 : audit_file(f.file);
631 0 : error = mnt_want_write_file(f.file);
632 0 : if (!error) {
633 0 : error = setxattr(file_mnt_user_ns(f.file),
634 : f.file->f_path.dentry, name,
635 : value, size, flags);
636 0 : mnt_drop_write_file(f.file);
637 : }
638 0 : fdput(f);
639 0 : return error;
640 : }
641 :
642 : /*
643 : * Extended attribute GET operations
644 : */
645 : static ssize_t
646 0 : getxattr(struct user_namespace *mnt_userns, struct dentry *d,
647 : const char __user *name, void __user *value, size_t size)
648 : {
649 : ssize_t error;
650 0 : void *kvalue = NULL;
651 : char kname[XATTR_NAME_MAX + 1];
652 :
653 0 : error = strncpy_from_user(kname, name, sizeof(kname));
654 0 : if (error == 0 || error == sizeof(kname))
655 0 : error = -ERANGE;
656 0 : if (error < 0)
657 : return error;
658 :
659 0 : if (size) {
660 0 : if (size > XATTR_SIZE_MAX)
661 0 : size = XATTR_SIZE_MAX;
662 0 : kvalue = kvzalloc(size, GFP_KERNEL);
663 0 : if (!kvalue)
664 : return -ENOMEM;
665 : }
666 :
667 0 : error = vfs_getxattr(mnt_userns, d, kname, kvalue, size);
668 0 : if (error > 0) {
669 0 : if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
670 0 : (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
671 : posix_acl_fix_xattr_to_user(mnt_userns, d_inode(d),
672 : kvalue, error);
673 0 : if (size && copy_to_user(value, kvalue, error))
674 0 : error = -EFAULT;
675 0 : } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
676 : /* The file system tried to returned a value bigger
677 : than XATTR_SIZE_MAX bytes. Not possible. */
678 0 : error = -E2BIG;
679 : }
680 :
681 0 : kvfree(kvalue);
682 :
683 0 : return error;
684 : }
685 :
686 0 : static ssize_t path_getxattr(const char __user *pathname,
687 : const char __user *name, void __user *value,
688 : size_t size, unsigned int lookup_flags)
689 : {
690 : struct path path;
691 : ssize_t error;
692 : retry:
693 0 : error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
694 0 : if (error)
695 : return error;
696 0 : error = getxattr(mnt_user_ns(path.mnt), path.dentry, name, value, size);
697 0 : path_put(&path);
698 0 : if (retry_estale(error, lookup_flags)) {
699 0 : lookup_flags |= LOOKUP_REVAL;
700 0 : goto retry;
701 : }
702 : return error;
703 : }
704 :
705 0 : SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
706 : const char __user *, name, void __user *, value, size_t, size)
707 : {
708 0 : return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW);
709 : }
710 :
711 0 : SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
712 : const char __user *, name, void __user *, value, size_t, size)
713 : {
714 0 : return path_getxattr(pathname, name, value, size, 0);
715 : }
716 :
717 0 : SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
718 : void __user *, value, size_t, size)
719 : {
720 0 : struct fd f = fdget(fd);
721 0 : ssize_t error = -EBADF;
722 :
723 0 : if (!f.file)
724 : return error;
725 0 : audit_file(f.file);
726 0 : error = getxattr(file_mnt_user_ns(f.file), f.file->f_path.dentry,
727 : name, value, size);
728 0 : fdput(f);
729 : return error;
730 : }
731 :
732 : /*
733 : * Extended attribute LIST operations
734 : */
735 : static ssize_t
736 0 : listxattr(struct dentry *d, char __user *list, size_t size)
737 : {
738 : ssize_t error;
739 0 : char *klist = NULL;
740 :
741 0 : if (size) {
742 0 : if (size > XATTR_LIST_MAX)
743 0 : size = XATTR_LIST_MAX;
744 0 : klist = kvmalloc(size, GFP_KERNEL);
745 0 : if (!klist)
746 : return -ENOMEM;
747 : }
748 :
749 0 : error = vfs_listxattr(d, klist, size);
750 0 : if (error > 0) {
751 0 : if (size && copy_to_user(list, klist, error))
752 0 : error = -EFAULT;
753 0 : } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
754 : /* The file system tried to returned a list bigger
755 : than XATTR_LIST_MAX bytes. Not possible. */
756 0 : error = -E2BIG;
757 : }
758 :
759 0 : kvfree(klist);
760 :
761 0 : return error;
762 : }
763 :
764 0 : static ssize_t path_listxattr(const char __user *pathname, char __user *list,
765 : size_t size, unsigned int lookup_flags)
766 : {
767 : struct path path;
768 : ssize_t error;
769 : retry:
770 0 : error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
771 0 : if (error)
772 : return error;
773 0 : error = listxattr(path.dentry, list, size);
774 0 : path_put(&path);
775 0 : if (retry_estale(error, lookup_flags)) {
776 0 : lookup_flags |= LOOKUP_REVAL;
777 0 : goto retry;
778 : }
779 : return error;
780 : }
781 :
782 0 : SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
783 : size_t, size)
784 : {
785 0 : return path_listxattr(pathname, list, size, LOOKUP_FOLLOW);
786 : }
787 :
788 0 : SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
789 : size_t, size)
790 : {
791 0 : return path_listxattr(pathname, list, size, 0);
792 : }
793 :
794 0 : SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
795 : {
796 0 : struct fd f = fdget(fd);
797 0 : ssize_t error = -EBADF;
798 :
799 0 : if (!f.file)
800 : return error;
801 0 : audit_file(f.file);
802 0 : error = listxattr(f.file->f_path.dentry, list, size);
803 0 : fdput(f);
804 : return error;
805 : }
806 :
807 : /*
808 : * Extended attribute REMOVE operations
809 : */
810 : static long
811 0 : removexattr(struct user_namespace *mnt_userns, struct dentry *d,
812 : const char __user *name)
813 : {
814 : int error;
815 : char kname[XATTR_NAME_MAX + 1];
816 :
817 0 : error = strncpy_from_user(kname, name, sizeof(kname));
818 0 : if (error == 0 || error == sizeof(kname))
819 0 : error = -ERANGE;
820 0 : if (error < 0)
821 0 : return error;
822 :
823 0 : return vfs_removexattr(mnt_userns, d, kname);
824 : }
825 :
826 0 : static int path_removexattr(const char __user *pathname,
827 : const char __user *name, unsigned int lookup_flags)
828 : {
829 : struct path path;
830 : int error;
831 : retry:
832 0 : error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
833 0 : if (error)
834 : return error;
835 0 : error = mnt_want_write(path.mnt);
836 0 : if (!error) {
837 0 : error = removexattr(mnt_user_ns(path.mnt), path.dentry, name);
838 0 : mnt_drop_write(path.mnt);
839 : }
840 0 : path_put(&path);
841 0 : if (retry_estale(error, lookup_flags)) {
842 0 : lookup_flags |= LOOKUP_REVAL;
843 0 : goto retry;
844 : }
845 : return error;
846 : }
847 :
848 0 : SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
849 : const char __user *, name)
850 : {
851 0 : return path_removexattr(pathname, name, LOOKUP_FOLLOW);
852 : }
853 :
854 0 : SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
855 : const char __user *, name)
856 : {
857 0 : return path_removexattr(pathname, name, 0);
858 : }
859 :
860 0 : SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
861 : {
862 0 : struct fd f = fdget(fd);
863 0 : int error = -EBADF;
864 :
865 0 : if (!f.file)
866 : return error;
867 0 : audit_file(f.file);
868 0 : error = mnt_want_write_file(f.file);
869 0 : if (!error) {
870 0 : error = removexattr(file_mnt_user_ns(f.file),
871 : f.file->f_path.dentry, name);
872 0 : mnt_drop_write_file(f.file);
873 : }
874 0 : fdput(f);
875 0 : return error;
876 : }
877 :
878 : /*
879 : * Combine the results of the list() operation from every xattr_handler in the
880 : * list.
881 : */
882 : ssize_t
883 0 : generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
884 : {
885 0 : const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
886 0 : unsigned int size = 0;
887 :
888 0 : if (!buffer) {
889 0 : for_each_xattr_handler(handlers, handler) {
890 0 : if (!handler->name ||
891 0 : (handler->list && !handler->list(dentry)))
892 0 : continue;
893 0 : size += strlen(handler->name) + 1;
894 : }
895 : } else {
896 0 : char *buf = buffer;
897 : size_t len;
898 :
899 0 : for_each_xattr_handler(handlers, handler) {
900 0 : if (!handler->name ||
901 0 : (handler->list && !handler->list(dentry)))
902 0 : continue;
903 0 : len = strlen(handler->name);
904 0 : if (len + 1 > buffer_size)
905 : return -ERANGE;
906 0 : memcpy(buf, handler->name, len + 1);
907 0 : buf += len + 1;
908 0 : buffer_size -= len + 1;
909 : }
910 0 : size = buf - buffer;
911 : }
912 0 : return size;
913 : }
914 : EXPORT_SYMBOL(generic_listxattr);
915 :
916 : /**
917 : * xattr_full_name - Compute full attribute name from suffix
918 : *
919 : * @handler: handler of the xattr_handler operation
920 : * @name: name passed to the xattr_handler operation
921 : *
922 : * The get and set xattr handler operations are called with the remainder of
923 : * the attribute name after skipping the handler's prefix: for example, "foo"
924 : * is passed to the get operation of a handler with prefix "user." to get
925 : * attribute "user.foo". The full name is still "there" in the name though.
926 : *
927 : * Note: the list xattr handler operation when called from the vfs is passed a
928 : * NULL name; some file systems use this operation internally, with varying
929 : * semantics.
930 : */
931 0 : const char *xattr_full_name(const struct xattr_handler *handler,
932 : const char *name)
933 : {
934 0 : size_t prefix_len = strlen(xattr_prefix(handler));
935 :
936 0 : return name - prefix_len;
937 : }
938 : EXPORT_SYMBOL(xattr_full_name);
939 :
940 : /*
941 : * Allocate new xattr and copy in the value; but leave the name to callers.
942 : */
943 0 : struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
944 : {
945 : struct simple_xattr *new_xattr;
946 : size_t len;
947 :
948 : /* wrap around? */
949 0 : len = sizeof(*new_xattr) + size;
950 0 : if (len < sizeof(*new_xattr))
951 : return NULL;
952 :
953 0 : new_xattr = kvmalloc(len, GFP_KERNEL);
954 0 : if (!new_xattr)
955 : return NULL;
956 :
957 0 : new_xattr->size = size;
958 0 : memcpy(new_xattr->value, value, size);
959 0 : return new_xattr;
960 : }
961 :
962 : /*
963 : * xattr GET operation for in-memory/pseudo filesystems
964 : */
965 0 : int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
966 : void *buffer, size_t size)
967 : {
968 : struct simple_xattr *xattr;
969 0 : int ret = -ENODATA;
970 :
971 0 : spin_lock(&xattrs->lock);
972 0 : list_for_each_entry(xattr, &xattrs->head, list) {
973 0 : if (strcmp(name, xattr->name))
974 0 : continue;
975 :
976 0 : ret = xattr->size;
977 0 : if (buffer) {
978 0 : if (size < xattr->size)
979 : ret = -ERANGE;
980 : else
981 0 : memcpy(buffer, xattr->value, xattr->size);
982 : }
983 : break;
984 : }
985 0 : spin_unlock(&xattrs->lock);
986 0 : return ret;
987 : }
988 :
989 : /**
990 : * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
991 : * @xattrs: target simple_xattr list
992 : * @name: name of the extended attribute
993 : * @value: value of the xattr. If %NULL, will remove the attribute.
994 : * @size: size of the new xattr
995 : * @flags: %XATTR_{CREATE|REPLACE}
996 : * @removed_size: returns size of the removed xattr, -1 if none removed
997 : *
998 : * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
999 : * with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist;
1000 : * otherwise, fails with -ENODATA.
1001 : *
1002 : * Returns 0 on success, -errno on failure.
1003 : */
1004 0 : int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
1005 : const void *value, size_t size, int flags,
1006 : ssize_t *removed_size)
1007 : {
1008 : struct simple_xattr *xattr;
1009 0 : struct simple_xattr *new_xattr = NULL;
1010 0 : int err = 0;
1011 :
1012 0 : if (removed_size)
1013 0 : *removed_size = -1;
1014 :
1015 : /* value == NULL means remove */
1016 0 : if (value) {
1017 0 : new_xattr = simple_xattr_alloc(value, size);
1018 0 : if (!new_xattr)
1019 : return -ENOMEM;
1020 :
1021 0 : new_xattr->name = kstrdup(name, GFP_KERNEL);
1022 0 : if (!new_xattr->name) {
1023 0 : kvfree(new_xattr);
1024 0 : return -ENOMEM;
1025 : }
1026 : }
1027 :
1028 0 : spin_lock(&xattrs->lock);
1029 0 : list_for_each_entry(xattr, &xattrs->head, list) {
1030 0 : if (!strcmp(name, xattr->name)) {
1031 0 : if (flags & XATTR_CREATE) {
1032 : xattr = new_xattr;
1033 : err = -EEXIST;
1034 0 : } else if (new_xattr) {
1035 0 : list_replace(&xattr->list, &new_xattr->list);
1036 0 : if (removed_size)
1037 0 : *removed_size = xattr->size;
1038 : } else {
1039 0 : list_del(&xattr->list);
1040 0 : if (removed_size)
1041 0 : *removed_size = xattr->size;
1042 : }
1043 : goto out;
1044 : }
1045 : }
1046 0 : if (flags & XATTR_REPLACE) {
1047 : xattr = new_xattr;
1048 : err = -ENODATA;
1049 : } else {
1050 0 : list_add(&new_xattr->list, &xattrs->head);
1051 0 : xattr = NULL;
1052 : }
1053 : out:
1054 0 : spin_unlock(&xattrs->lock);
1055 0 : if (xattr) {
1056 0 : kfree(xattr->name);
1057 0 : kvfree(xattr);
1058 : }
1059 : return err;
1060 :
1061 : }
1062 :
1063 : static bool xattr_is_trusted(const char *name)
1064 : {
1065 0 : return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
1066 : }
1067 :
1068 0 : static int xattr_list_one(char **buffer, ssize_t *remaining_size,
1069 : const char *name)
1070 : {
1071 0 : size_t len = strlen(name) + 1;
1072 0 : if (*buffer) {
1073 0 : if (*remaining_size < len)
1074 : return -ERANGE;
1075 0 : memcpy(*buffer, name, len);
1076 0 : *buffer += len;
1077 : }
1078 0 : *remaining_size -= len;
1079 0 : return 0;
1080 : }
1081 :
1082 : /*
1083 : * xattr LIST operation for in-memory/pseudo filesystems
1084 : */
1085 0 : ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
1086 : char *buffer, size_t size)
1087 : {
1088 0 : bool trusted = capable(CAP_SYS_ADMIN);
1089 : struct simple_xattr *xattr;
1090 0 : ssize_t remaining_size = size;
1091 0 : int err = 0;
1092 :
1093 : #ifdef CONFIG_FS_POSIX_ACL
1094 : if (IS_POSIXACL(inode)) {
1095 : if (inode->i_acl) {
1096 : err = xattr_list_one(&buffer, &remaining_size,
1097 : XATTR_NAME_POSIX_ACL_ACCESS);
1098 : if (err)
1099 : return err;
1100 : }
1101 : if (inode->i_default_acl) {
1102 : err = xattr_list_one(&buffer, &remaining_size,
1103 : XATTR_NAME_POSIX_ACL_DEFAULT);
1104 : if (err)
1105 : return err;
1106 : }
1107 : }
1108 : #endif
1109 :
1110 0 : spin_lock(&xattrs->lock);
1111 0 : list_for_each_entry(xattr, &xattrs->head, list) {
1112 : /* skip "trusted." attributes for unprivileged callers */
1113 0 : if (!trusted && xattr_is_trusted(xattr->name))
1114 0 : continue;
1115 :
1116 0 : err = xattr_list_one(&buffer, &remaining_size, xattr->name);
1117 0 : if (err)
1118 : break;
1119 : }
1120 0 : spin_unlock(&xattrs->lock);
1121 :
1122 0 : return err ? err : size - remaining_size;
1123 : }
1124 :
1125 : /*
1126 : * Adds an extended attribute to the list
1127 : */
1128 0 : void simple_xattr_list_add(struct simple_xattrs *xattrs,
1129 : struct simple_xattr *new_xattr)
1130 : {
1131 0 : spin_lock(&xattrs->lock);
1132 0 : list_add(&new_xattr->list, &xattrs->head);
1133 0 : spin_unlock(&xattrs->lock);
1134 0 : }
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