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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#include "internal.h"
29
30static const char *
31strcmp_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 */
55static const struct xattr_handler *
56xattr_resolve_name(struct inode *inode, const char **name)
57{
58 const struct xattr_handler **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(-EIO);
64 return ERR_PTR(-EOPNOTSUPP);
65 }
66 for_each_xattr_handler(handlers, handler) {
67 const char *n;
68
69 n = strcmp_prefix(*name, xattr_prefix(handler));
70 if (n) {
71 if (!handler->prefix ^ !*n) {
72 if (*n)
73 continue;
74 return ERR_PTR(-EINVAL);
75 }
76 *name = n;
77 return handler;
78 }
79 }
80 return ERR_PTR(-EOPNOTSUPP);
81}
82
83/**
84 * may_write_xattr - check whether inode allows writing xattr
85 * @mnt_userns: User namespace 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 */
97int may_write_xattr(struct user_namespace *mnt_userns, 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(mnt_userns, 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 */
112static int
113xattr_permission(struct user_namespace *mnt_userns, struct inode *inode,
114 const char *name, int mask)
115{
116 if (mask & MAY_WRITE) {
117 int ret;
118
119 ret = may_write_xattr(mnt_userns, 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(mnt_userns, inode))
152 return -EPERM;
153 }
154
155 return inode_permission(mnt_userns, inode, mask);
156}
157
158/*
159 * Look for any handler that deals with the specified namespace.
160 */
161int
162xattr_supported_namespace(struct inode *inode, const char *prefix)
163{
164 const struct xattr_handler **handlers = inode->i_sb->s_xattr;
165 const struct xattr_handler *handler;
166 size_t preflen;
167
168 if (!(inode->i_opflags & IOP_XATTR)) {
169 if (unlikely(is_bad_inode(inode)))
170 return -EIO;
171 return -EOPNOTSUPP;
172 }
173
174 preflen = strlen(prefix);
175
176 for_each_xattr_handler(handlers, handler) {
177 if (!strncmp(xattr_prefix(handler), prefix, preflen))
178 return 0;
179 }
180
181 return -EOPNOTSUPP;
182}
183EXPORT_SYMBOL(xattr_supported_namespace);
184
185int
186__vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
187 struct inode *inode, const char *name, const void *value,
188 size_t size, int flags)
189{
190 const struct xattr_handler *handler;
191
192 if (is_posix_acl_xattr(name))
193 return -EOPNOTSUPP;
194
195 handler = xattr_resolve_name(inode, &name);
196 if (IS_ERR(handler))
197 return PTR_ERR(handler);
198 if (!handler->set)
199 return -EOPNOTSUPP;
200 if (size == 0)
201 value = ""; /* empty EA, do not remove */
202 return handler->set(handler, mnt_userns, dentry, inode, name, value,
203 size, flags);
204}
205EXPORT_SYMBOL(__vfs_setxattr);
206
207/**
208 * __vfs_setxattr_noperm - perform setxattr operation without performing
209 * permission checks.
210 *
211 * @mnt_userns: user namespace of the mount the inode was found from
212 * @dentry: object to perform setxattr on
213 * @name: xattr name to set
214 * @value: value to set @name to
215 * @size: size of @value
216 * @flags: flags to pass into filesystem operations
217 *
218 * returns the result of the internal setxattr or setsecurity operations.
219 *
220 * This function requires the caller to lock the inode's i_mutex before it
221 * is executed. It also assumes that the caller will make the appropriate
222 * permission checks.
223 */
224int __vfs_setxattr_noperm(struct user_namespace *mnt_userns,
225 struct dentry *dentry, const char *name,
226 const void *value, size_t size, int flags)
227{
228 struct inode *inode = dentry->d_inode;
229 int error = -EAGAIN;
230 int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
231 XATTR_SECURITY_PREFIX_LEN);
232
233 if (issec)
234 inode->i_flags &= ~S_NOSEC;
235 if (inode->i_opflags & IOP_XATTR) {
236 error = __vfs_setxattr(mnt_userns, dentry, inode, name, value,
237 size, flags);
238 if (!error) {
239 fsnotify_xattr(dentry);
240 security_inode_post_setxattr(dentry, name, value,
241 size, flags);
242 }
243 } else {
244 if (unlikely(is_bad_inode(inode)))
245 return -EIO;
246 }
247 if (error == -EAGAIN) {
248 error = -EOPNOTSUPP;
249
250 if (issec) {
251 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
252
253 error = security_inode_setsecurity(inode, suffix, value,
254 size, flags);
255 if (!error)
256 fsnotify_xattr(dentry);
257 }
258 }
259
260 return error;
261}
262
263/**
264 * __vfs_setxattr_locked - set an extended attribute while holding the inode
265 * lock
266 *
267 * @mnt_userns: user namespace of the mount of the target inode
268 * @dentry: object to perform setxattr on
269 * @name: xattr name to set
270 * @value: value to set @name to
271 * @size: size of @value
272 * @flags: flags to pass into filesystem operations
273 * @delegated_inode: on return, will contain an inode pointer that
274 * a delegation was broken on, NULL if none.
275 */
276int
277__vfs_setxattr_locked(struct user_namespace *mnt_userns, struct dentry *dentry,
278 const char *name, const void *value, size_t size,
279 int flags, struct inode **delegated_inode)
280{
281 struct inode *inode = dentry->d_inode;
282 int error;
283
284 error = xattr_permission(mnt_userns, inode, name, MAY_WRITE);
285 if (error)
286 return error;
287
288 error = security_inode_setxattr(mnt_userns, dentry, name, value, size,
289 flags);
290 if (error)
291 goto out;
292
293 error = try_break_deleg(inode, delegated_inode);
294 if (error)
295 goto out;
296
297 error = __vfs_setxattr_noperm(mnt_userns, dentry, name, value,
298 size, flags);
299
300out:
301 return error;
302}
303EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
304
305int
306vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
307 const char *name, const void *value, size_t size, int flags)
308{
309 struct inode *inode = dentry->d_inode;
310 struct inode *delegated_inode = NULL;
311 const void *orig_value = value;
312 int error;
313
314 if (size && strcmp(name, XATTR_NAME_CAPS) == 0) {
315 error = cap_convert_nscap(mnt_userns, dentry, &value, size);
316 if (error < 0)
317 return error;
318 size = error;
319 }
320
321retry_deleg:
322 inode_lock(inode);
323 error = __vfs_setxattr_locked(mnt_userns, dentry, name, value, size,
324 flags, &delegated_inode);
325 inode_unlock(inode);
326
327 if (delegated_inode) {
328 error = break_deleg_wait(&delegated_inode);
329 if (!error)
330 goto retry_deleg;
331 }
332 if (value != orig_value)
333 kfree(value);
334
335 return error;
336}
337EXPORT_SYMBOL_GPL(vfs_setxattr);
338
339static ssize_t
340xattr_getsecurity(struct user_namespace *mnt_userns, struct inode *inode,
341 const char *name, void *value, size_t size)
342{
343 void *buffer = NULL;
344 ssize_t len;
345
346 if (!value || !size) {
347 len = security_inode_getsecurity(mnt_userns, inode, name,
348 &buffer, false);
349 goto out_noalloc;
350 }
351
352 len = security_inode_getsecurity(mnt_userns, inode, name, &buffer,
353 true);
354 if (len < 0)
355 return len;
356 if (size < len) {
357 len = -ERANGE;
358 goto out;
359 }
360 memcpy(value, buffer, len);
361out:
362 kfree(buffer);
363out_noalloc:
364 return len;
365}
366
367/*
368 * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
369 *
370 * Allocate memory, if not already allocated, or re-allocate correct size,
371 * before retrieving the extended attribute. The xattr value buffer should
372 * always be freed by the caller, even on error.
373 *
374 * Returns the result of alloc, if failed, or the getxattr operation.
375 */
376int
377vfs_getxattr_alloc(struct user_namespace *mnt_userns, struct dentry *dentry,
378 const char *name, char **xattr_value, size_t xattr_size,
379 gfp_t flags)
380{
381 const struct xattr_handler *handler;
382 struct inode *inode = dentry->d_inode;
383 char *value = *xattr_value;
384 int error;
385
386 error = xattr_permission(mnt_userns, inode, name, MAY_READ);
387 if (error)
388 return error;
389
390 handler = xattr_resolve_name(inode, &name);
391 if (IS_ERR(handler))
392 return PTR_ERR(handler);
393 if (!handler->get)
394 return -EOPNOTSUPP;
395 error = handler->get(handler, dentry, inode, name, NULL, 0);
396 if (error < 0)
397 return error;
398
399 if (!value || (error > xattr_size)) {
400 value = krealloc(*xattr_value, error + 1, flags);
401 if (!value)
402 return -ENOMEM;
403 memset(value, 0, error + 1);
404 }
405
406 error = handler->get(handler, dentry, inode, name, value, error);
407 *xattr_value = value;
408 return error;
409}
410
411ssize_t
412__vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
413 void *value, size_t size)
414{
415 const struct xattr_handler *handler;
416
417 if (is_posix_acl_xattr(name))
418 return -EOPNOTSUPP;
419
420 handler = xattr_resolve_name(inode, &name);
421 if (IS_ERR(handler))
422 return PTR_ERR(handler);
423 if (!handler->get)
424 return -EOPNOTSUPP;
425 return handler->get(handler, dentry, inode, name, value, size);
426}
427EXPORT_SYMBOL(__vfs_getxattr);
428
429ssize_t
430vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
431 const char *name, void *value, size_t size)
432{
433 struct inode *inode = dentry->d_inode;
434 int error;
435
436 error = xattr_permission(mnt_userns, inode, name, MAY_READ);
437 if (error)
438 return error;
439
440 error = security_inode_getxattr(dentry, name);
441 if (error)
442 return error;
443
444 if (!strncmp(name, XATTR_SECURITY_PREFIX,
445 XATTR_SECURITY_PREFIX_LEN)) {
446 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
447 int ret = xattr_getsecurity(mnt_userns, inode, suffix, value,
448 size);
449 /*
450 * Only overwrite the return value if a security module
451 * is actually active.
452 */
453 if (ret == -EOPNOTSUPP)
454 goto nolsm;
455 return ret;
456 }
457nolsm:
458 return __vfs_getxattr(dentry, inode, name, value, size);
459}
460EXPORT_SYMBOL_GPL(vfs_getxattr);
461
462ssize_t
463vfs_listxattr(struct dentry *dentry, char *list, size_t size)
464{
465 struct inode *inode = d_inode(dentry);
466 ssize_t error;
467
468 error = security_inode_listxattr(dentry);
469 if (error)
470 return error;
471 if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) {
472 error = inode->i_op->listxattr(dentry, list, size);
473 } else {
474 error = security_inode_listsecurity(inode, list, size);
475 if (size && error > size)
476 error = -ERANGE;
477 }
478 return error;
479}
480EXPORT_SYMBOL_GPL(vfs_listxattr);
481
482int
483__vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
484 const char *name)
485{
486 struct inode *inode = d_inode(dentry);
487 const struct xattr_handler *handler;
488
489 if (is_posix_acl_xattr(name))
490 return -EOPNOTSUPP;
491
492 handler = xattr_resolve_name(inode, &name);
493 if (IS_ERR(handler))
494 return PTR_ERR(handler);
495 if (!handler->set)
496 return -EOPNOTSUPP;
497 return handler->set(handler, mnt_userns, dentry, inode, name, NULL, 0,
498 XATTR_REPLACE);
499}
500EXPORT_SYMBOL(__vfs_removexattr);
501
502/**
503 * __vfs_removexattr_locked - set an extended attribute while holding the inode
504 * lock
505 *
506 * @mnt_userns: user namespace of the mount of the target inode
507 * @dentry: object to perform setxattr on
508 * @name: name of xattr to remove
509 * @delegated_inode: on return, will contain an inode pointer that
510 * a delegation was broken on, NULL if none.
511 */
512int
513__vfs_removexattr_locked(struct user_namespace *mnt_userns,
514 struct dentry *dentry, const char *name,
515 struct inode **delegated_inode)
516{
517 struct inode *inode = dentry->d_inode;
518 int error;
519
520 error = xattr_permission(mnt_userns, inode, name, MAY_WRITE);
521 if (error)
522 return error;
523
524 error = security_inode_removexattr(mnt_userns, dentry, name);
525 if (error)
526 goto out;
527
528 error = try_break_deleg(inode, delegated_inode);
529 if (error)
530 goto out;
531
532 error = __vfs_removexattr(mnt_userns, dentry, name);
533
534 if (!error) {
535 fsnotify_xattr(dentry);
536 evm_inode_post_removexattr(dentry, name);
537 }
538
539out:
540 return error;
541}
542EXPORT_SYMBOL_GPL(__vfs_removexattr_locked);
543
544int
545vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
546 const char *name)
547{
548 struct inode *inode = dentry->d_inode;
549 struct inode *delegated_inode = NULL;
550 int error;
551
552retry_deleg:
553 inode_lock(inode);
554 error = __vfs_removexattr_locked(mnt_userns, dentry,
555 name, &delegated_inode);
556 inode_unlock(inode);
557
558 if (delegated_inode) {
559 error = break_deleg_wait(&delegated_inode);
560 if (!error)
561 goto retry_deleg;
562 }
563
564 return error;
565}
566EXPORT_SYMBOL_GPL(vfs_removexattr);
567
568/*
569 * Extended attribute SET operations
570 */
571
572int setxattr_copy(const char __user *name, struct xattr_ctx *ctx)
573{
574 int error;
575
576 if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
577 return -EINVAL;
578
579 error = strncpy_from_user(ctx->kname->name, name,
580 sizeof(ctx->kname->name));
581 if (error == 0 || error == sizeof(ctx->kname->name))
582 return -ERANGE;
583 if (error < 0)
584 return error;
585
586 error = 0;
587 if (ctx->size) {
588 if (ctx->size > XATTR_SIZE_MAX)
589 return -E2BIG;
590
591 ctx->kvalue = vmemdup_user(ctx->cvalue, ctx->size);
592 if (IS_ERR(ctx->kvalue)) {
593 error = PTR_ERR(ctx->kvalue);
594 ctx->kvalue = NULL;
595 }
596 }
597
598 return error;
599}
600
601int do_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
602 struct xattr_ctx *ctx)
603{
604 if (is_posix_acl_xattr(ctx->kname->name))
605 return do_set_acl(idmap, dentry, ctx->kname->name,
606 ctx->kvalue, ctx->size);
607
608 return vfs_setxattr(mnt_idmap_owner(idmap), dentry, ctx->kname->name,
609 ctx->kvalue, ctx->size, ctx->flags);
610}
611
612static long
613setxattr(struct mnt_idmap *idmap, struct dentry *d,
614 const char __user *name, const void __user *value, size_t size,
615 int flags)
616{
617 struct xattr_name kname;
618 struct xattr_ctx ctx = {
619 .cvalue = value,
620 .kvalue = NULL,
621 .size = size,
622 .kname = &kname,
623 .flags = flags,
624 };
625 int error;
626
627 error = setxattr_copy(name, &ctx);
628 if (error)
629 return error;
630
631 error = do_setxattr(idmap, d, &ctx);
632
633 kvfree(ctx.kvalue);
634 return error;
635}
636
637static int path_setxattr(const char __user *pathname,
638 const char __user *name, const void __user *value,
639 size_t size, int flags, unsigned int lookup_flags)
640{
641 struct path path;
642 int error;
643
644retry:
645 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
646 if (error)
647 return error;
648 error = mnt_want_write(path.mnt);
649 if (!error) {
650 error = setxattr(mnt_idmap(path.mnt), path.dentry, name,
651 value, size, flags);
652 mnt_drop_write(path.mnt);
653 }
654 path_put(&path);
655 if (retry_estale(error, lookup_flags)) {
656 lookup_flags |= LOOKUP_REVAL;
657 goto retry;
658 }
659 return error;
660}
661
662SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
663 const char __user *, name, const void __user *, value,
664 size_t, size, int, flags)
665{
666 return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW);
667}
668
669SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
670 const char __user *, name, const void __user *, value,
671 size_t, size, int, flags)
672{
673 return path_setxattr(pathname, name, value, size, flags, 0);
674}
675
676SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
677 const void __user *,value, size_t, size, int, flags)
678{
679 struct fd f = fdget(fd);
680 int error = -EBADF;
681
682 if (!f.file)
683 return error;
684 audit_file(f.file);
685 error = mnt_want_write_file(f.file);
686 if (!error) {
687 error = setxattr(file_mnt_idmap(f.file),
688 f.file->f_path.dentry, name,
689 value, size, flags);
690 mnt_drop_write_file(f.file);
691 }
692 fdput(f);
693 return error;
694}
695
696/*
697 * Extended attribute GET operations
698 */
699ssize_t
700do_getxattr(struct mnt_idmap *idmap, struct dentry *d,
701 struct xattr_ctx *ctx)
702{
703 ssize_t error;
704 char *kname = ctx->kname->name;
705
706 if (ctx->size) {
707 if (ctx->size > XATTR_SIZE_MAX)
708 ctx->size = XATTR_SIZE_MAX;
709 ctx->kvalue = kvzalloc(ctx->size, GFP_KERNEL);
710 if (!ctx->kvalue)
711 return -ENOMEM;
712 }
713
714 if (is_posix_acl_xattr(ctx->kname->name))
715 error = do_get_acl(idmap, d, kname, ctx->kvalue, ctx->size);
716 else
717 error = vfs_getxattr(mnt_idmap_owner(idmap), d, kname,
718 ctx->kvalue, ctx->size);
719 if (error > 0) {
720 if (ctx->size && copy_to_user(ctx->value, ctx->kvalue, error))
721 error = -EFAULT;
722 } else if (error == -ERANGE && ctx->size >= XATTR_SIZE_MAX) {
723 /* The file system tried to returned a value bigger
724 than XATTR_SIZE_MAX bytes. Not possible. */
725 error = -E2BIG;
726 }
727
728 return error;
729}
730
731static ssize_t
732getxattr(struct mnt_idmap *idmap, struct dentry *d,
733 const char __user *name, void __user *value, size_t size)
734{
735 ssize_t error;
736 struct xattr_name kname;
737 struct xattr_ctx ctx = {
738 .value = value,
739 .kvalue = NULL,
740 .size = size,
741 .kname = &kname,
742 .flags = 0,
743 };
744
745 error = strncpy_from_user(kname.name, name, sizeof(kname.name));
746 if (error == 0 || error == sizeof(kname.name))
747 error = -ERANGE;
748 if (error < 0)
749 return error;
750
751 error = do_getxattr(idmap, d, &ctx);
752
753 kvfree(ctx.kvalue);
754 return error;
755}
756
757static ssize_t path_getxattr(const char __user *pathname,
758 const char __user *name, void __user *value,
759 size_t size, unsigned int lookup_flags)
760{
761 struct path path;
762 ssize_t error;
763retry:
764 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
765 if (error)
766 return error;
767 error = getxattr(mnt_idmap(path.mnt), path.dentry, name, value, size);
768 path_put(&path);
769 if (retry_estale(error, lookup_flags)) {
770 lookup_flags |= LOOKUP_REVAL;
771 goto retry;
772 }
773 return error;
774}
775
776SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
777 const char __user *, name, void __user *, value, size_t, size)
778{
779 return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW);
780}
781
782SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
783 const char __user *, name, void __user *, value, size_t, size)
784{
785 return path_getxattr(pathname, name, value, size, 0);
786}
787
788SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
789 void __user *, value, size_t, size)
790{
791 struct fd f = fdget(fd);
792 ssize_t error = -EBADF;
793
794 if (!f.file)
795 return error;
796 audit_file(f.file);
797 error = getxattr(file_mnt_idmap(f.file), f.file->f_path.dentry,
798 name, value, size);
799 fdput(f);
800 return error;
801}
802
803/*
804 * Extended attribute LIST operations
805 */
806static ssize_t
807listxattr(struct dentry *d, char __user *list, size_t size)
808{
809 ssize_t error;
810 char *klist = NULL;
811
812 if (size) {
813 if (size > XATTR_LIST_MAX)
814 size = XATTR_LIST_MAX;
815 klist = kvmalloc(size, GFP_KERNEL);
816 if (!klist)
817 return -ENOMEM;
818 }
819
820 error = vfs_listxattr(d, klist, size);
821 if (error > 0) {
822 if (size && copy_to_user(list, klist, error))
823 error = -EFAULT;
824 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
825 /* The file system tried to returned a list bigger
826 than XATTR_LIST_MAX bytes. Not possible. */
827 error = -E2BIG;
828 }
829
830 kvfree(klist);
831
832 return error;
833}
834
835static ssize_t path_listxattr(const char __user *pathname, char __user *list,
836 size_t size, unsigned int lookup_flags)
837{
838 struct path path;
839 ssize_t error;
840retry:
841 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
842 if (error)
843 return error;
844 error = listxattr(path.dentry, list, size);
845 path_put(&path);
846 if (retry_estale(error, lookup_flags)) {
847 lookup_flags |= LOOKUP_REVAL;
848 goto retry;
849 }
850 return error;
851}
852
853SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
854 size_t, size)
855{
856 return path_listxattr(pathname, list, size, LOOKUP_FOLLOW);
857}
858
859SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
860 size_t, size)
861{
862 return path_listxattr(pathname, list, size, 0);
863}
864
865SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
866{
867 struct fd f = fdget(fd);
868 ssize_t error = -EBADF;
869
870 if (!f.file)
871 return error;
872 audit_file(f.file);
873 error = listxattr(f.file->f_path.dentry, list, size);
874 fdput(f);
875 return error;
876}
877
878/*
879 * Extended attribute REMOVE operations
880 */
881static long
882removexattr(struct mnt_idmap *idmap, struct dentry *d,
883 const char __user *name)
884{
885 int error;
886 char kname[XATTR_NAME_MAX + 1];
887
888 error = strncpy_from_user(kname, name, sizeof(kname));
889 if (error == 0 || error == sizeof(kname))
890 error = -ERANGE;
891 if (error < 0)
892 return error;
893
894 if (is_posix_acl_xattr(kname))
895 return vfs_remove_acl(mnt_idmap_owner(idmap), d, kname);
896
897 return vfs_removexattr(mnt_idmap_owner(idmap), d, kname);
898}
899
900static int path_removexattr(const char __user *pathname,
901 const char __user *name, unsigned int lookup_flags)
902{
903 struct path path;
904 int error;
905retry:
906 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
907 if (error)
908 return error;
909 error = mnt_want_write(path.mnt);
910 if (!error) {
911 error = removexattr(mnt_idmap(path.mnt), path.dentry, name);
912 mnt_drop_write(path.mnt);
913 }
914 path_put(&path);
915 if (retry_estale(error, lookup_flags)) {
916 lookup_flags |= LOOKUP_REVAL;
917 goto retry;
918 }
919 return error;
920}
921
922SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
923 const char __user *, name)
924{
925 return path_removexattr(pathname, name, LOOKUP_FOLLOW);
926}
927
928SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
929 const char __user *, name)
930{
931 return path_removexattr(pathname, name, 0);
932}
933
934SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
935{
936 struct fd f = fdget(fd);
937 int error = -EBADF;
938
939 if (!f.file)
940 return error;
941 audit_file(f.file);
942 error = mnt_want_write_file(f.file);
943 if (!error) {
944 error = removexattr(file_mnt_idmap(f.file),
945 f.file->f_path.dentry, name);
946 mnt_drop_write_file(f.file);
947 }
948 fdput(f);
949 return error;
950}
951
952/*
953 * Combine the results of the list() operation from every xattr_handler in the
954 * list.
955 */
956ssize_t
957generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
958{
959 const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
960 unsigned int size = 0;
961
962 if (!buffer) {
963 for_each_xattr_handler(handlers, handler) {
964 if (!handler->name ||
965 (handler->list && !handler->list(dentry)))
966 continue;
967 size += strlen(handler->name) + 1;
968 }
969 } else {
970 char *buf = buffer;
971 size_t len;
972
973 for_each_xattr_handler(handlers, handler) {
974 if (!handler->name ||
975 (handler->list && !handler->list(dentry)))
976 continue;
977 len = strlen(handler->name);
978 if (len + 1 > buffer_size)
979 return -ERANGE;
980 memcpy(buf, handler->name, len + 1);
981 buf += len + 1;
982 buffer_size -= len + 1;
983 }
984 size = buf - buffer;
985 }
986 return size;
987}
988EXPORT_SYMBOL(generic_listxattr);
989
990/**
991 * xattr_full_name - Compute full attribute name from suffix
992 *
993 * @handler: handler of the xattr_handler operation
994 * @name: name passed to the xattr_handler operation
995 *
996 * The get and set xattr handler operations are called with the remainder of
997 * the attribute name after skipping the handler's prefix: for example, "foo"
998 * is passed to the get operation of a handler with prefix "user." to get
999 * attribute "user.foo". The full name is still "there" in the name though.
1000 *
1001 * Note: the list xattr handler operation when called from the vfs is passed a
1002 * NULL name; some file systems use this operation internally, with varying
1003 * semantics.
1004 */
1005const char *xattr_full_name(const struct xattr_handler *handler,
1006 const char *name)
1007{
1008 size_t prefix_len = strlen(xattr_prefix(handler));
1009
1010 return name - prefix_len;
1011}
1012EXPORT_SYMBOL(xattr_full_name);
1013
1014/**
1015 * free_simple_xattr - free an xattr object
1016 * @xattr: the xattr object
1017 *
1018 * Free the xattr object. Can handle @xattr being NULL.
1019 */
1020static inline void free_simple_xattr(struct simple_xattr *xattr)
1021{
1022 if (xattr)
1023 kfree(xattr->name);
1024 kvfree(xattr);
1025}
1026
1027/**
1028 * simple_xattr_alloc - allocate new xattr object
1029 * @value: value of the xattr object
1030 * @size: size of @value
1031 *
1032 * Allocate a new xattr object and initialize respective members. The caller is
1033 * responsible for handling the name of the xattr.
1034 *
1035 * Return: On success a new xattr object is returned. On failure NULL is
1036 * returned.
1037 */
1038struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
1039{
1040 struct simple_xattr *new_xattr;
1041 size_t len;
1042
1043 /* wrap around? */
1044 len = sizeof(*new_xattr) + size;
1045 if (len < sizeof(*new_xattr))
1046 return NULL;
1047
1048 new_xattr = kvmalloc(len, GFP_KERNEL);
1049 if (!new_xattr)
1050 return NULL;
1051
1052 new_xattr->size = size;
1053 memcpy(new_xattr->value, value, size);
1054 return new_xattr;
1055}
1056
1057/**
1058 * rbtree_simple_xattr_cmp - compare xattr name with current rbtree xattr entry
1059 * @key: xattr name
1060 * @node: current node
1061 *
1062 * Compare the xattr name with the xattr name attached to @node in the rbtree.
1063 *
1064 * Return: Negative value if continuing left, positive if continuing right, 0
1065 * if the xattr attached to @node matches @key.
1066 */
1067static int rbtree_simple_xattr_cmp(const void *key, const struct rb_node *node)
1068{
1069 const char *xattr_name = key;
1070 const struct simple_xattr *xattr;
1071
1072 xattr = rb_entry(node, struct simple_xattr, rb_node);
1073 return strcmp(xattr->name, xattr_name);
1074}
1075
1076/**
1077 * rbtree_simple_xattr_node_cmp - compare two xattr rbtree nodes
1078 * @new_node: new node
1079 * @node: current node
1080 *
1081 * Compare the xattr attached to @new_node with the xattr attached to @node.
1082 *
1083 * Return: Negative value if continuing left, positive if continuing right, 0
1084 * if the xattr attached to @new_node matches the xattr attached to @node.
1085 */
1086static int rbtree_simple_xattr_node_cmp(struct rb_node *new_node,
1087 const struct rb_node *node)
1088{
1089 struct simple_xattr *xattr;
1090 xattr = rb_entry(new_node, struct simple_xattr, rb_node);
1091 return rbtree_simple_xattr_cmp(xattr->name, node);
1092}
1093
1094/**
1095 * simple_xattr_get - get an xattr object
1096 * @xattrs: the header of the xattr object
1097 * @name: the name of the xattr to retrieve
1098 * @buffer: the buffer to store the value into
1099 * @size: the size of @buffer
1100 *
1101 * Try to find and retrieve the xattr object associated with @name.
1102 * If @buffer is provided store the value of @xattr in @buffer
1103 * otherwise just return the length. The size of @buffer is limited
1104 * to XATTR_SIZE_MAX which currently is 65536.
1105 *
1106 * Return: On success the length of the xattr value is returned. On error a
1107 * negative error code is returned.
1108 */
1109int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
1110 void *buffer, size_t size)
1111{
1112 struct simple_xattr *xattr = NULL;
1113 struct rb_node *rbp;
1114 int ret = -ENODATA;
1115
1116 read_lock(&xattrs->lock);
1117 rbp = rb_find(name, &xattrs->rb_root, rbtree_simple_xattr_cmp);
1118 if (rbp) {
1119 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1120 ret = xattr->size;
1121 if (buffer) {
1122 if (size < xattr->size)
1123 ret = -ERANGE;
1124 else
1125 memcpy(buffer, xattr->value, xattr->size);
1126 }
1127 }
1128 read_unlock(&xattrs->lock);
1129 return ret;
1130}
1131
1132/**
1133 * simple_xattr_set - set an xattr object
1134 * @xattrs: the header of the xattr object
1135 * @name: the name of the xattr to retrieve
1136 * @value: the value to store along the xattr
1137 * @size: the size of @value
1138 * @flags: the flags determining how to set the xattr
1139 * @removed_size: the size of the removed xattr
1140 *
1141 * Set a new xattr object.
1142 * If @value is passed a new xattr object will be allocated. If XATTR_REPLACE
1143 * is specified in @flags a matching xattr object for @name must already exist.
1144 * If it does it will be replaced with the new xattr object. If it doesn't we
1145 * fail. If XATTR_CREATE is specified and a matching xattr does already exist
1146 * we fail. If it doesn't we create a new xattr. If @flags is zero we simply
1147 * insert the new xattr replacing any existing one.
1148 *
1149 * If @value is empty and a matching xattr object is found we delete it if
1150 * XATTR_REPLACE is specified in @flags or @flags is zero.
1151 *
1152 * If @value is empty and no matching xattr object for @name is found we do
1153 * nothing if XATTR_CREATE is specified in @flags or @flags is zero. For
1154 * XATTR_REPLACE we fail as mentioned above.
1155 *
1156 * Return: On success zero and on error a negative error code is returned.
1157 */
1158int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
1159 const void *value, size_t size, int flags,
1160 ssize_t *removed_size)
1161{
1162 struct simple_xattr *xattr = NULL, *new_xattr = NULL;
1163 struct rb_node *parent = NULL, **rbp;
1164 int err = 0, ret;
1165
1166 if (removed_size)
1167 *removed_size = -1;
1168
1169 /* value == NULL means remove */
1170 if (value) {
1171 new_xattr = simple_xattr_alloc(value, size);
1172 if (!new_xattr)
1173 return -ENOMEM;
1174
1175 new_xattr->name = kstrdup(name, GFP_KERNEL);
1176 if (!new_xattr->name) {
1177 free_simple_xattr(new_xattr);
1178 return -ENOMEM;
1179 }
1180 }
1181
1182 write_lock(&xattrs->lock);
1183 rbp = &xattrs->rb_root.rb_node;
1184 while (*rbp) {
1185 parent = *rbp;
1186 ret = rbtree_simple_xattr_cmp(name, *rbp);
1187 if (ret < 0)
1188 rbp = &(*rbp)->rb_left;
1189 else if (ret > 0)
1190 rbp = &(*rbp)->rb_right;
1191 else
1192 xattr = rb_entry(*rbp, struct simple_xattr, rb_node);
1193 if (xattr)
1194 break;
1195 }
1196
1197 if (xattr) {
1198 /* Fail if XATTR_CREATE is requested and the xattr exists. */
1199 if (flags & XATTR_CREATE) {
1200 err = -EEXIST;
1201 goto out_unlock;
1202 }
1203
1204 if (new_xattr)
1205 rb_replace_node(&xattr->rb_node, &new_xattr->rb_node,
1206 &xattrs->rb_root);
1207 else
1208 rb_erase(&xattr->rb_node, &xattrs->rb_root);
1209 if (!err && removed_size)
1210 *removed_size = xattr->size;
1211 } else {
1212 /* Fail if XATTR_REPLACE is requested but no xattr is found. */
1213 if (flags & XATTR_REPLACE) {
1214 err = -ENODATA;
1215 goto out_unlock;
1216 }
1217
1218 /*
1219 * If XATTR_CREATE or no flags are specified together with a
1220 * new value simply insert it.
1221 */
1222 if (new_xattr) {
1223 rb_link_node(&new_xattr->rb_node, parent, rbp);
1224 rb_insert_color(&new_xattr->rb_node, &xattrs->rb_root);
1225 }
1226
1227 /*
1228 * If XATTR_CREATE or no flags are specified and neither an
1229 * old or new xattr exist then we don't need to do anything.
1230 */
1231 }
1232
1233out_unlock:
1234 write_unlock(&xattrs->lock);
1235 if (err)
1236 free_simple_xattr(new_xattr);
1237 else
1238 free_simple_xattr(xattr);
1239 return err;
1240
1241}
1242
1243static bool xattr_is_trusted(const char *name)
1244{
1245 return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
1246}
1247
1248static int xattr_list_one(char **buffer, ssize_t *remaining_size,
1249 const char *name)
1250{
1251 size_t len = strlen(name) + 1;
1252 if (*buffer) {
1253 if (*remaining_size < len)
1254 return -ERANGE;
1255 memcpy(*buffer, name, len);
1256 *buffer += len;
1257 }
1258 *remaining_size -= len;
1259 return 0;
1260}
1261
1262/**
1263 * simple_xattr_list - list all xattr objects
1264 * @inode: inode from which to get the xattrs
1265 * @xattrs: the header of the xattr object
1266 * @buffer: the buffer to store all xattrs into
1267 * @size: the size of @buffer
1268 *
1269 * List all xattrs associated with @inode. If @buffer is NULL we returned
1270 * the required size of the buffer. If @buffer is provided we store the
1271 * xattrs value into it provided it is big enough.
1272 *
1273 * Note, the number of xattr names that can be listed with listxattr(2) is
1274 * limited to XATTR_LIST_MAX aka 65536 bytes. If a larger buffer is passed
1275 * then vfs_listxattr() caps it to XATTR_LIST_MAX and if more xattr names
1276 * are found it will return -E2BIG.
1277 *
1278 * Return: On success the required size or the size of the copied xattrs is
1279 * returned. On error a negative error code is returned.
1280 */
1281ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
1282 char *buffer, size_t size)
1283{
1284 bool trusted = ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN);
1285 struct simple_xattr *xattr;
1286 struct rb_node *rbp;
1287 ssize_t remaining_size = size;
1288 int err = 0;
1289
1290#ifdef CONFIG_FS_POSIX_ACL
1291 if (IS_POSIXACL(inode)) {
1292 if (inode->i_acl) {
1293 err = xattr_list_one(&buffer, &remaining_size,
1294 XATTR_NAME_POSIX_ACL_ACCESS);
1295 if (err)
1296 return err;
1297 }
1298 if (inode->i_default_acl) {
1299 err = xattr_list_one(&buffer, &remaining_size,
1300 XATTR_NAME_POSIX_ACL_DEFAULT);
1301 if (err)
1302 return err;
1303 }
1304 }
1305#endif
1306
1307 read_lock(&xattrs->lock);
1308 for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
1309 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1310
1311 /* skip "trusted." attributes for unprivileged callers */
1312 if (!trusted && xattr_is_trusted(xattr->name))
1313 continue;
1314
1315 err = xattr_list_one(&buffer, &remaining_size, xattr->name);
1316 if (err)
1317 break;
1318 }
1319 read_unlock(&xattrs->lock);
1320
1321 return err ? err : size - remaining_size;
1322}
1323
1324/**
1325 * rbtree_simple_xattr_less - compare two xattr rbtree nodes
1326 * @new_node: new node
1327 * @node: current node
1328 *
1329 * Compare the xattr attached to @new_node with the xattr attached to @node.
1330 * Note that this function technically tolerates duplicate entries.
1331 *
1332 * Return: True if insertion point in the rbtree is found.
1333 */
1334static bool rbtree_simple_xattr_less(struct rb_node *new_node,
1335 const struct rb_node *node)
1336{
1337 return rbtree_simple_xattr_node_cmp(new_node, node) < 0;
1338}
1339
1340/**
1341 * simple_xattr_add - add xattr objects
1342 * @xattrs: the header of the xattr object
1343 * @new_xattr: the xattr object to add
1344 *
1345 * Add an xattr object to @xattrs. This assumes no replacement or removal
1346 * of matching xattrs is wanted. Should only be called during inode
1347 * initialization when a few distinct initial xattrs are supposed to be set.
1348 */
1349void simple_xattr_add(struct simple_xattrs *xattrs,
1350 struct simple_xattr *new_xattr)
1351{
1352 write_lock(&xattrs->lock);
1353 rb_add(&new_xattr->rb_node, &xattrs->rb_root, rbtree_simple_xattr_less);
1354 write_unlock(&xattrs->lock);
1355}
1356
1357/**
1358 * simple_xattrs_init - initialize new xattr header
1359 * @xattrs: header to initialize
1360 *
1361 * Initialize relevant fields of a an xattr header.
1362 */
1363void simple_xattrs_init(struct simple_xattrs *xattrs)
1364{
1365 xattrs->rb_root = RB_ROOT;
1366 rwlock_init(&xattrs->lock);
1367}
1368
1369/**
1370 * simple_xattrs_free - free xattrs
1371 * @xattrs: xattr header whose xattrs to destroy
1372 *
1373 * Destroy all xattrs in @xattr. When this is called no one can hold a
1374 * reference to any of the xattrs anymore.
1375 */
1376void simple_xattrs_free(struct simple_xattrs *xattrs)
1377{
1378 struct rb_node *rbp;
1379
1380 rbp = rb_first(&xattrs->rb_root);
1381 while (rbp) {
1382 struct simple_xattr *xattr;
1383 struct rb_node *rbp_next;
1384
1385 rbp_next = rb_next(rbp);
1386 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1387 rb_erase(&xattr->rb_node, &xattrs->rb_root);
1388 free_simple_xattr(xattr);
1389 rbp = rbp_next;
1390 }
1391}
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
30static const char *
31strcmp_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 */
55static const struct xattr_handler *
56xattr_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(-EIO);
64 return ERR_PTR(-EOPNOTSUPP);
65 }
66 for_each_xattr_handler(handlers, handler) {
67 const char *n;
68
69 n = strcmp_prefix(*name, xattr_prefix(handler));
70 if (n) {
71 if (!handler->prefix ^ !*n) {
72 if (*n)
73 continue;
74 return ERR_PTR(-EINVAL);
75 }
76 *name = n;
77 return handler;
78 }
79 }
80 return ERR_PTR(-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 */
97int 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 */
112static int
113xattr_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 */
161int
162xattr_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}
181EXPORT_SYMBOL(xattr_supports_user_prefix);
182
183int
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);
194 if (IS_ERR(handler))
195 return PTR_ERR(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}
203EXPORT_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 */
222int __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, 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 */
274int
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
298out:
299 return error;
300}
301EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
302
303int
304vfs_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, &value, size);
314 if (error < 0)
315 return error;
316 size = error;
317 }
318
319retry_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);
327 if (!error)
328 goto retry_deleg;
329 }
330 if (value != orig_value)
331 kfree(value);
332
333 return error;
334}
335EXPORT_SYMBOL_GPL(vfs_setxattr);
336
337static ssize_t
338xattr_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, false);
347 goto out_noalloc;
348 }
349
350 len = security_inode_getsecurity(idmap, inode, name, &buffer,
351 true);
352 if (len < 0)
353 return len;
354 if (size < len) {
355 len = -ERANGE;
356 goto out;
357 }
358 memcpy(value, buffer, len);
359out:
360 kfree(buffer);
361out_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 */
374int
375vfs_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);
389 if (IS_ERR(handler))
390 return PTR_ERR(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(*xattr_value, 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
409ssize_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);
419 if (IS_ERR(handler))
420 return PTR_ERR(handler);
421 if (!handler->get)
422 return -EOPNOTSUPP;
423 return handler->get(handler, dentry, inode, name, value, size);
424}
425EXPORT_SYMBOL(__vfs_getxattr);
426
427ssize_t
428vfs_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, 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 }
455nolsm:
456 return __vfs_getxattr(dentry, inode, name, value, size);
457}
458EXPORT_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 */
482ssize_t
483vfs_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, list, size);
496 if (size && error > size)
497 error = -ERANGE;
498 }
499 return error;
500}
501EXPORT_SYMBOL_GPL(vfs_listxattr);
502
503int
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);
514 if (IS_ERR(handler))
515 return PTR_ERR(handler);
516 if (!handler->set)
517 return -EOPNOTSUPP;
518 return handler->set(handler, idmap, dentry, inode, name, NULL, 0,
519 XATTR_REPLACE);
520}
521EXPORT_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 */
533int
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
560out:
561 return error;
562}
563EXPORT_SYMBOL_GPL(__vfs_removexattr_locked);
564
565int
566vfs_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
573retry_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);
581 if (!error)
582 goto retry_deleg;
583 }
584
585 return error;
586}
587EXPORT_SYMBOL_GPL(vfs_removexattr);
588
589int import_xattr_name(struct xattr_name *kname, const char __user *name)
590{
591 int error = strncpy_from_user(kname->name, name,
592 sizeof(kname->name));
593 if (error == 0 || error == sizeof(kname->name))
594 return -ERANGE;
595 if (error < 0)
596 return error;
597 return 0;
598}
599
600/*
601 * Extended attribute SET operations
602 */
603
604int setxattr_copy(const char __user *name, struct kernel_xattr_ctx *ctx)
605{
606 int error;
607
608 if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
609 return -EINVAL;
610
611 error = import_xattr_name(ctx->kname, name);
612 if (error)
613 return error;
614
615 if (ctx->size) {
616 if (ctx->size > XATTR_SIZE_MAX)
617 return -E2BIG;
618
619 ctx->kvalue = vmemdup_user(ctx->cvalue, ctx->size);
620 if (IS_ERR(ctx->kvalue)) {
621 error = PTR_ERR(ctx->kvalue);
622 ctx->kvalue = NULL;
623 }
624 }
625
626 return error;
627}
628
629static int do_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
630 struct kernel_xattr_ctx *ctx)
631{
632 if (is_posix_acl_xattr(ctx->kname->name))
633 return do_set_acl(idmap, dentry, ctx->kname->name,
634 ctx->kvalue, ctx->size);
635
636 return vfs_setxattr(idmap, dentry, ctx->kname->name,
637 ctx->kvalue, ctx->size, ctx->flags);
638}
639
640int file_setxattr(struct file *f, struct kernel_xattr_ctx *ctx)
641{
642 int error = mnt_want_write_file(f);
643
644 if (!error) {
645 audit_file(f);
646 error = do_setxattr(file_mnt_idmap(f), f->f_path.dentry, ctx);
647 mnt_drop_write_file(f);
648 }
649 return error;
650}
651
652/* unconditionally consumes filename */
653int filename_setxattr(int dfd, struct filename *filename,
654 unsigned int lookup_flags, struct kernel_xattr_ctx *ctx)
655{
656 struct path path;
657 int error;
658
659retry:
660 error = filename_lookup(dfd, filename, lookup_flags, &path, NULL);
661 if (error)
662 goto out;
663 error = mnt_want_write(path.mnt);
664 if (!error) {
665 error = do_setxattr(mnt_idmap(path.mnt), path.dentry, ctx);
666 mnt_drop_write(path.mnt);
667 }
668 path_put(&path);
669 if (retry_estale(error, lookup_flags)) {
670 lookup_flags |= LOOKUP_REVAL;
671 goto retry;
672 }
673
674out:
675 putname(filename);
676 return error;
677}
678
679static int path_setxattrat(int dfd, const char __user *pathname,
680 unsigned int at_flags, const char __user *name,
681 const void __user *value, size_t size, int flags)
682{
683 struct xattr_name kname;
684 struct kernel_xattr_ctx ctx = {
685 .cvalue = value,
686 .kvalue = NULL,
687 .size = size,
688 .kname = &kname,
689 .flags = flags,
690 };
691 struct filename *filename;
692 unsigned int lookup_flags = 0;
693 int error;
694
695 if ((at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
696 return -EINVAL;
697
698 if (!(at_flags & AT_SYMLINK_NOFOLLOW))
699 lookup_flags = LOOKUP_FOLLOW;
700
701 error = setxattr_copy(name, &ctx);
702 if (error)
703 return error;
704
705 filename = getname_maybe_null(pathname, at_flags);
706 if (!filename) {
707 CLASS(fd, f)(dfd);
708 if (fd_empty(f))
709 error = -EBADF;
710 else
711 error = file_setxattr(fd_file(f), &ctx);
712 } else {
713 error = filename_setxattr(dfd, filename, lookup_flags, &ctx);
714 }
715 kvfree(ctx.kvalue);
716 return error;
717}
718
719SYSCALL_DEFINE6(setxattrat, int, dfd, const char __user *, pathname, unsigned int, at_flags,
720 const char __user *, name, const struct xattr_args __user *, uargs,
721 size_t, usize)
722{
723 struct xattr_args args = {};
724 int error;
725
726 BUILD_BUG_ON(sizeof(struct xattr_args) < XATTR_ARGS_SIZE_VER0);
727 BUILD_BUG_ON(sizeof(struct xattr_args) != XATTR_ARGS_SIZE_LATEST);
728
729 if (unlikely(usize < XATTR_ARGS_SIZE_VER0))
730 return -EINVAL;
731 if (usize > PAGE_SIZE)
732 return -E2BIG;
733
734 error = copy_struct_from_user(&args, sizeof(args), uargs, usize);
735 if (error)
736 return error;
737
738 return path_setxattrat(dfd, pathname, at_flags, name,
739 u64_to_user_ptr(args.value), args.size,
740 args.flags);
741}
742
743SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
744 const char __user *, name, const void __user *, value,
745 size_t, size, int, flags)
746{
747 return path_setxattrat(AT_FDCWD, pathname, 0, name, value, size, flags);
748}
749
750SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
751 const char __user *, name, const void __user *, value,
752 size_t, size, int, flags)
753{
754 return path_setxattrat(AT_FDCWD, pathname, AT_SYMLINK_NOFOLLOW, name,
755 value, size, flags);
756}
757
758SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
759 const void __user *,value, size_t, size, int, flags)
760{
761 return path_setxattrat(fd, NULL, AT_EMPTY_PATH, name,
762 value, size, flags);
763}
764
765/*
766 * Extended attribute GET operations
767 */
768static ssize_t
769do_getxattr(struct mnt_idmap *idmap, struct dentry *d,
770 struct kernel_xattr_ctx *ctx)
771{
772 ssize_t error;
773 char *kname = ctx->kname->name;
774 void *kvalue = NULL;
775
776 if (ctx->size) {
777 if (ctx->size > XATTR_SIZE_MAX)
778 ctx->size = XATTR_SIZE_MAX;
779 kvalue = kvzalloc(ctx->size, GFP_KERNEL);
780 if (!kvalue)
781 return -ENOMEM;
782 }
783
784 if (is_posix_acl_xattr(kname))
785 error = do_get_acl(idmap, d, kname, kvalue, ctx->size);
786 else
787 error = vfs_getxattr(idmap, d, kname, kvalue, ctx->size);
788 if (error > 0) {
789 if (ctx->size && copy_to_user(ctx->value, kvalue, error))
790 error = -EFAULT;
791 } else if (error == -ERANGE && ctx->size >= XATTR_SIZE_MAX) {
792 /* The file system tried to returned a value bigger
793 than XATTR_SIZE_MAX bytes. Not possible. */
794 error = -E2BIG;
795 }
796
797 kvfree(kvalue);
798 return error;
799}
800
801ssize_t file_getxattr(struct file *f, struct kernel_xattr_ctx *ctx)
802{
803 audit_file(f);
804 return do_getxattr(file_mnt_idmap(f), f->f_path.dentry, ctx);
805}
806
807/* unconditionally consumes filename */
808ssize_t filename_getxattr(int dfd, struct filename *filename,
809 unsigned int lookup_flags, struct kernel_xattr_ctx *ctx)
810{
811 struct path path;
812 ssize_t error;
813retry:
814 error = filename_lookup(dfd, filename, lookup_flags, &path, NULL);
815 if (error)
816 goto out;
817 error = do_getxattr(mnt_idmap(path.mnt), path.dentry, ctx);
818 path_put(&path);
819 if (retry_estale(error, lookup_flags)) {
820 lookup_flags |= LOOKUP_REVAL;
821 goto retry;
822 }
823out:
824 putname(filename);
825 return error;
826}
827
828static ssize_t path_getxattrat(int dfd, const char __user *pathname,
829 unsigned int at_flags, const char __user *name,
830 void __user *value, size_t size)
831{
832 struct xattr_name kname;
833 struct kernel_xattr_ctx ctx = {
834 .value = value,
835 .size = size,
836 .kname = &kname,
837 .flags = 0,
838 };
839 struct filename *filename;
840 ssize_t error;
841
842 if ((at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
843 return -EINVAL;
844
845 error = import_xattr_name(&kname, name);
846 if (error)
847 return error;
848
849 filename = getname_maybe_null(pathname, at_flags);
850 if (!filename) {
851 CLASS(fd, f)(dfd);
852 if (fd_empty(f))
853 return -EBADF;
854 return file_getxattr(fd_file(f), &ctx);
855 } else {
856 int lookup_flags = 0;
857 if (!(at_flags & AT_SYMLINK_NOFOLLOW))
858 lookup_flags = LOOKUP_FOLLOW;
859 return filename_getxattr(dfd, filename, lookup_flags, &ctx);
860 }
861}
862
863SYSCALL_DEFINE6(getxattrat, int, dfd, const char __user *, pathname, unsigned int, at_flags,
864 const char __user *, name, struct xattr_args __user *, uargs, size_t, usize)
865{
866 struct xattr_args args = {};
867 int error;
868
869 BUILD_BUG_ON(sizeof(struct xattr_args) < XATTR_ARGS_SIZE_VER0);
870 BUILD_BUG_ON(sizeof(struct xattr_args) != XATTR_ARGS_SIZE_LATEST);
871
872 if (unlikely(usize < XATTR_ARGS_SIZE_VER0))
873 return -EINVAL;
874 if (usize > PAGE_SIZE)
875 return -E2BIG;
876
877 error = copy_struct_from_user(&args, sizeof(args), uargs, usize);
878 if (error)
879 return error;
880
881 if (args.flags != 0)
882 return -EINVAL;
883
884 return path_getxattrat(dfd, pathname, at_flags, name,
885 u64_to_user_ptr(args.value), args.size);
886}
887
888SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
889 const char __user *, name, void __user *, value, size_t, size)
890{
891 return path_getxattrat(AT_FDCWD, pathname, 0, name, value, size);
892}
893
894SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
895 const char __user *, name, void __user *, value, size_t, size)
896{
897 return path_getxattrat(AT_FDCWD, pathname, AT_SYMLINK_NOFOLLOW, name,
898 value, size);
899}
900
901SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
902 void __user *, value, size_t, size)
903{
904 return path_getxattrat(fd, NULL, AT_EMPTY_PATH, name, value, size);
905}
906
907/*
908 * Extended attribute LIST operations
909 */
910static ssize_t
911listxattr(struct dentry *d, char __user *list, size_t size)
912{
913 ssize_t error;
914 char *klist = NULL;
915
916 if (size) {
917 if (size > XATTR_LIST_MAX)
918 size = XATTR_LIST_MAX;
919 klist = kvmalloc(size, GFP_KERNEL);
920 if (!klist)
921 return -ENOMEM;
922 }
923
924 error = vfs_listxattr(d, klist, size);
925 if (error > 0) {
926 if (size && copy_to_user(list, klist, error))
927 error = -EFAULT;
928 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
929 /* The file system tried to returned a list bigger
930 than XATTR_LIST_MAX bytes. Not possible. */
931 error = -E2BIG;
932 }
933
934 kvfree(klist);
935
936 return error;
937}
938
939static
940ssize_t file_listxattr(struct file *f, char __user *list, size_t size)
941{
942 audit_file(f);
943 return listxattr(f->f_path.dentry, list, size);
944}
945
946/* unconditionally consumes filename */
947static
948ssize_t filename_listxattr(int dfd, struct filename *filename,
949 unsigned int lookup_flags,
950 char __user *list, size_t size)
951{
952 struct path path;
953 ssize_t error;
954retry:
955 error = filename_lookup(dfd, filename, lookup_flags, &path, NULL);
956 if (error)
957 goto out;
958 error = listxattr(path.dentry, list, size);
959 path_put(&path);
960 if (retry_estale(error, lookup_flags)) {
961 lookup_flags |= LOOKUP_REVAL;
962 goto retry;
963 }
964out:
965 putname(filename);
966 return error;
967}
968
969static ssize_t path_listxattrat(int dfd, const char __user *pathname,
970 unsigned int at_flags, char __user *list,
971 size_t size)
972{
973 struct filename *filename;
974 int lookup_flags;
975
976 if ((at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
977 return -EINVAL;
978
979 filename = getname_maybe_null(pathname, at_flags);
980 if (!filename) {
981 CLASS(fd, f)(dfd);
982 if (fd_empty(f))
983 return -EBADF;
984 return file_listxattr(fd_file(f), list, size);
985 }
986
987 lookup_flags = (at_flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
988 return filename_listxattr(dfd, filename, lookup_flags, list, size);
989}
990
991SYSCALL_DEFINE5(listxattrat, int, dfd, const char __user *, pathname,
992 unsigned int, at_flags,
993 char __user *, list, size_t, size)
994{
995 return path_listxattrat(dfd, pathname, at_flags, list, size);
996}
997
998SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
999 size_t, size)
1000{
1001 return path_listxattrat(AT_FDCWD, pathname, 0, list, size);
1002}
1003
1004SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
1005 size_t, size)
1006{
1007 return path_listxattrat(AT_FDCWD, pathname, AT_SYMLINK_NOFOLLOW, list, size);
1008}
1009
1010SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
1011{
1012 return path_listxattrat(fd, NULL, AT_EMPTY_PATH, list, size);
1013}
1014
1015/*
1016 * Extended attribute REMOVE operations
1017 */
1018static long
1019removexattr(struct mnt_idmap *idmap, struct dentry *d, const char *name)
1020{
1021 if (is_posix_acl_xattr(name))
1022 return vfs_remove_acl(idmap, d, name);
1023 return vfs_removexattr(idmap, d, name);
1024}
1025
1026static int file_removexattr(struct file *f, struct xattr_name *kname)
1027{
1028 int error = mnt_want_write_file(f);
1029
1030 if (!error) {
1031 audit_file(f);
1032 error = removexattr(file_mnt_idmap(f),
1033 f->f_path.dentry, kname->name);
1034 mnt_drop_write_file(f);
1035 }
1036 return error;
1037}
1038
1039/* unconditionally consumes filename */
1040static int filename_removexattr(int dfd, struct filename *filename,
1041 unsigned int lookup_flags, struct xattr_name *kname)
1042{
1043 struct path path;
1044 int error;
1045
1046retry:
1047 error = filename_lookup(dfd, filename, lookup_flags, &path, NULL);
1048 if (error)
1049 goto out;
1050 error = mnt_want_write(path.mnt);
1051 if (!error) {
1052 error = removexattr(mnt_idmap(path.mnt), path.dentry, kname->name);
1053 mnt_drop_write(path.mnt);
1054 }
1055 path_put(&path);
1056 if (retry_estale(error, lookup_flags)) {
1057 lookup_flags |= LOOKUP_REVAL;
1058 goto retry;
1059 }
1060out:
1061 putname(filename);
1062 return error;
1063}
1064
1065static int path_removexattrat(int dfd, const char __user *pathname,
1066 unsigned int at_flags, const char __user *name)
1067{
1068 struct xattr_name kname;
1069 struct filename *filename;
1070 unsigned int lookup_flags;
1071 int error;
1072
1073 if ((at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
1074 return -EINVAL;
1075
1076 error = import_xattr_name(&kname, name);
1077 if (error)
1078 return error;
1079
1080 filename = getname_maybe_null(pathname, at_flags);
1081 if (!filename) {
1082 CLASS(fd, f)(dfd);
1083 if (fd_empty(f))
1084 return -EBADF;
1085 return file_removexattr(fd_file(f), &kname);
1086 }
1087 lookup_flags = (at_flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
1088 return filename_removexattr(dfd, filename, lookup_flags, &kname);
1089}
1090
1091SYSCALL_DEFINE4(removexattrat, int, dfd, const char __user *, pathname,
1092 unsigned int, at_flags, const char __user *, name)
1093{
1094 return path_removexattrat(dfd, pathname, at_flags, name);
1095}
1096
1097SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
1098 const char __user *, name)
1099{
1100 return path_removexattrat(AT_FDCWD, pathname, 0, name);
1101}
1102
1103SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
1104 const char __user *, name)
1105{
1106 return path_removexattrat(AT_FDCWD, pathname, AT_SYMLINK_NOFOLLOW, name);
1107}
1108
1109SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
1110{
1111 return path_removexattrat(fd, NULL, AT_EMPTY_PATH, name);
1112}
1113
1114int xattr_list_one(char **buffer, ssize_t *remaining_size, const char *name)
1115{
1116 size_t len;
1117
1118 len = strlen(name) + 1;
1119 if (*buffer) {
1120 if (*remaining_size < len)
1121 return -ERANGE;
1122 memcpy(*buffer, name, len);
1123 *buffer += len;
1124 }
1125 *remaining_size -= len;
1126 return 0;
1127}
1128
1129/**
1130 * generic_listxattr - run through a dentry's xattr list() operations
1131 * @dentry: dentry to list the xattrs
1132 * @buffer: result buffer
1133 * @buffer_size: size of @buffer
1134 *
1135 * Combine the results of the list() operation from every xattr_handler in the
1136 * xattr_handler stack.
1137 *
1138 * Note that this will not include the entries for POSIX ACLs.
1139 */
1140ssize_t
1141generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
1142{
1143 const struct xattr_handler *handler, * const *handlers = dentry->d_sb->s_xattr;
1144 ssize_t remaining_size = buffer_size;
1145
1146 for_each_xattr_handler(handlers, handler) {
1147 int err;
1148
1149 if (!handler->name || (handler->list && !handler->list(dentry)))
1150 continue;
1151 err = xattr_list_one(&buffer, &remaining_size, handler->name);
1152 if (err)
1153 return err;
1154 }
1155
1156 return buffer_size - remaining_size;
1157}
1158EXPORT_SYMBOL(generic_listxattr);
1159
1160/**
1161 * xattr_full_name - Compute full attribute name from suffix
1162 *
1163 * @handler: handler of the xattr_handler operation
1164 * @name: name passed to the xattr_handler operation
1165 *
1166 * The get and set xattr handler operations are called with the remainder of
1167 * the attribute name after skipping the handler's prefix: for example, "foo"
1168 * is passed to the get operation of a handler with prefix "user." to get
1169 * attribute "user.foo". The full name is still "there" in the name though.
1170 *
1171 * Note: the list xattr handler operation when called from the vfs is passed a
1172 * NULL name; some file systems use this operation internally, with varying
1173 * semantics.
1174 */
1175const char *xattr_full_name(const struct xattr_handler *handler,
1176 const char *name)
1177{
1178 size_t prefix_len = strlen(xattr_prefix(handler));
1179
1180 return name - prefix_len;
1181}
1182EXPORT_SYMBOL(xattr_full_name);
1183
1184/**
1185 * simple_xattr_space - estimate the memory used by a simple xattr
1186 * @name: the full name of the xattr
1187 * @size: the size of its value
1188 *
1189 * This takes no account of how much larger the two slab objects actually are:
1190 * that would depend on the slab implementation, when what is required is a
1191 * deterministic number, which grows with name length and size and quantity.
1192 *
1193 * Return: The approximate number of bytes of memory used by such an xattr.
1194 */
1195size_t simple_xattr_space(const char *name, size_t size)
1196{
1197 /*
1198 * Use "40" instead of sizeof(struct simple_xattr), to return the
1199 * same result on 32-bit and 64-bit, and even if simple_xattr grows.
1200 */
1201 return 40 + size + strlen(name);
1202}
1203
1204/**
1205 * simple_xattr_free - free an xattr object
1206 * @xattr: the xattr object
1207 *
1208 * Free the xattr object. Can handle @xattr being NULL.
1209 */
1210void simple_xattr_free(struct simple_xattr *xattr)
1211{
1212 if (xattr)
1213 kfree(xattr->name);
1214 kvfree(xattr);
1215}
1216
1217/**
1218 * simple_xattr_alloc - allocate new xattr object
1219 * @value: value of the xattr object
1220 * @size: size of @value
1221 *
1222 * Allocate a new xattr object and initialize respective members. The caller is
1223 * responsible for handling the name of the xattr.
1224 *
1225 * Return: On success a new xattr object is returned. On failure NULL is
1226 * returned.
1227 */
1228struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
1229{
1230 struct simple_xattr *new_xattr;
1231 size_t len;
1232
1233 /* wrap around? */
1234 len = sizeof(*new_xattr) + size;
1235 if (len < sizeof(*new_xattr))
1236 return NULL;
1237
1238 new_xattr = kvmalloc(len, GFP_KERNEL_ACCOUNT);
1239 if (!new_xattr)
1240 return NULL;
1241
1242 new_xattr->size = size;
1243 memcpy(new_xattr->value, value, size);
1244 return new_xattr;
1245}
1246
1247/**
1248 * rbtree_simple_xattr_cmp - compare xattr name with current rbtree xattr entry
1249 * @key: xattr name
1250 * @node: current node
1251 *
1252 * Compare the xattr name with the xattr name attached to @node in the rbtree.
1253 *
1254 * Return: Negative value if continuing left, positive if continuing right, 0
1255 * if the xattr attached to @node matches @key.
1256 */
1257static int rbtree_simple_xattr_cmp(const void *key, const struct rb_node *node)
1258{
1259 const char *xattr_name = key;
1260 const struct simple_xattr *xattr;
1261
1262 xattr = rb_entry(node, struct simple_xattr, rb_node);
1263 return strcmp(xattr->name, xattr_name);
1264}
1265
1266/**
1267 * rbtree_simple_xattr_node_cmp - compare two xattr rbtree nodes
1268 * @new_node: new node
1269 * @node: current node
1270 *
1271 * Compare the xattr attached to @new_node with the xattr attached to @node.
1272 *
1273 * Return: Negative value if continuing left, positive if continuing right, 0
1274 * if the xattr attached to @new_node matches the xattr attached to @node.
1275 */
1276static int rbtree_simple_xattr_node_cmp(struct rb_node *new_node,
1277 const struct rb_node *node)
1278{
1279 struct simple_xattr *xattr;
1280 xattr = rb_entry(new_node, struct simple_xattr, rb_node);
1281 return rbtree_simple_xattr_cmp(xattr->name, node);
1282}
1283
1284/**
1285 * simple_xattr_get - get an xattr object
1286 * @xattrs: the header of the xattr object
1287 * @name: the name of the xattr to retrieve
1288 * @buffer: the buffer to store the value into
1289 * @size: the size of @buffer
1290 *
1291 * Try to find and retrieve the xattr object associated with @name.
1292 * If @buffer is provided store the value of @xattr in @buffer
1293 * otherwise just return the length. The size of @buffer is limited
1294 * to XATTR_SIZE_MAX which currently is 65536.
1295 *
1296 * Return: On success the length of the xattr value is returned. On error a
1297 * negative error code is returned.
1298 */
1299int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
1300 void *buffer, size_t size)
1301{
1302 struct simple_xattr *xattr = NULL;
1303 struct rb_node *rbp;
1304 int ret = -ENODATA;
1305
1306 read_lock(&xattrs->lock);
1307 rbp = rb_find(name, &xattrs->rb_root, rbtree_simple_xattr_cmp);
1308 if (rbp) {
1309 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1310 ret = xattr->size;
1311 if (buffer) {
1312 if (size < xattr->size)
1313 ret = -ERANGE;
1314 else
1315 memcpy(buffer, xattr->value, xattr->size);
1316 }
1317 }
1318 read_unlock(&xattrs->lock);
1319 return ret;
1320}
1321
1322/**
1323 * simple_xattr_set - set an xattr object
1324 * @xattrs: the header of the xattr object
1325 * @name: the name of the xattr to retrieve
1326 * @value: the value to store along the xattr
1327 * @size: the size of @value
1328 * @flags: the flags determining how to set the xattr
1329 *
1330 * Set a new xattr object.
1331 * If @value is passed a new xattr object will be allocated. If XATTR_REPLACE
1332 * is specified in @flags a matching xattr object for @name must already exist.
1333 * If it does it will be replaced with the new xattr object. If it doesn't we
1334 * fail. If XATTR_CREATE is specified and a matching xattr does already exist
1335 * we fail. If it doesn't we create a new xattr. If @flags is zero we simply
1336 * insert the new xattr replacing any existing one.
1337 *
1338 * If @value is empty and a matching xattr object is found we delete it if
1339 * XATTR_REPLACE is specified in @flags or @flags is zero.
1340 *
1341 * If @value is empty and no matching xattr object for @name is found we do
1342 * nothing if XATTR_CREATE is specified in @flags or @flags is zero. For
1343 * XATTR_REPLACE we fail as mentioned above.
1344 *
1345 * Return: On success, the removed or replaced xattr is returned, to be freed
1346 * by the caller; or NULL if none. On failure a negative error code is returned.
1347 */
1348struct simple_xattr *simple_xattr_set(struct simple_xattrs *xattrs,
1349 const char *name, const void *value,
1350 size_t size, int flags)
1351{
1352 struct simple_xattr *old_xattr = NULL, *new_xattr = NULL;
1353 struct rb_node *parent = NULL, **rbp;
1354 int err = 0, ret;
1355
1356 /* value == NULL means remove */
1357 if (value) {
1358 new_xattr = simple_xattr_alloc(value, size);
1359 if (!new_xattr)
1360 return ERR_PTR(-ENOMEM);
1361
1362 new_xattr->name = kstrdup(name, GFP_KERNEL_ACCOUNT);
1363 if (!new_xattr->name) {
1364 simple_xattr_free(new_xattr);
1365 return ERR_PTR(-ENOMEM);
1366 }
1367 }
1368
1369 write_lock(&xattrs->lock);
1370 rbp = &xattrs->rb_root.rb_node;
1371 while (*rbp) {
1372 parent = *rbp;
1373 ret = rbtree_simple_xattr_cmp(name, *rbp);
1374 if (ret < 0)
1375 rbp = &(*rbp)->rb_left;
1376 else if (ret > 0)
1377 rbp = &(*rbp)->rb_right;
1378 else
1379 old_xattr = rb_entry(*rbp, struct simple_xattr, rb_node);
1380 if (old_xattr)
1381 break;
1382 }
1383
1384 if (old_xattr) {
1385 /* Fail if XATTR_CREATE is requested and the xattr exists. */
1386 if (flags & XATTR_CREATE) {
1387 err = -EEXIST;
1388 goto out_unlock;
1389 }
1390
1391 if (new_xattr)
1392 rb_replace_node(&old_xattr->rb_node,
1393 &new_xattr->rb_node, &xattrs->rb_root);
1394 else
1395 rb_erase(&old_xattr->rb_node, &xattrs->rb_root);
1396 } else {
1397 /* Fail if XATTR_REPLACE is requested but no xattr is found. */
1398 if (flags & XATTR_REPLACE) {
1399 err = -ENODATA;
1400 goto out_unlock;
1401 }
1402
1403 /*
1404 * If XATTR_CREATE or no flags are specified together with a
1405 * new value simply insert it.
1406 */
1407 if (new_xattr) {
1408 rb_link_node(&new_xattr->rb_node, parent, rbp);
1409 rb_insert_color(&new_xattr->rb_node, &xattrs->rb_root);
1410 }
1411
1412 /*
1413 * If XATTR_CREATE or no flags are specified and neither an
1414 * old or new xattr exist then we don't need to do anything.
1415 */
1416 }
1417
1418out_unlock:
1419 write_unlock(&xattrs->lock);
1420 if (!err)
1421 return old_xattr;
1422 simple_xattr_free(new_xattr);
1423 return ERR_PTR(err);
1424}
1425
1426static bool xattr_is_trusted(const char *name)
1427{
1428 return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
1429}
1430
1431/**
1432 * simple_xattr_list - list all xattr objects
1433 * @inode: inode from which to get the xattrs
1434 * @xattrs: the header of the xattr object
1435 * @buffer: the buffer to store all xattrs into
1436 * @size: the size of @buffer
1437 *
1438 * List all xattrs associated with @inode. If @buffer is NULL we returned
1439 * the required size of the buffer. If @buffer is provided we store the
1440 * xattrs value into it provided it is big enough.
1441 *
1442 * Note, the number of xattr names that can be listed with listxattr(2) is
1443 * limited to XATTR_LIST_MAX aka 65536 bytes. If a larger buffer is passed
1444 * then vfs_listxattr() caps it to XATTR_LIST_MAX and if more xattr names
1445 * are found it will return -E2BIG.
1446 *
1447 * Return: On success the required size or the size of the copied xattrs is
1448 * returned. On error a negative error code is returned.
1449 */
1450ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
1451 char *buffer, size_t size)
1452{
1453 bool trusted = ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN);
1454 struct simple_xattr *xattr;
1455 struct rb_node *rbp;
1456 ssize_t remaining_size = size;
1457 int err = 0;
1458
1459 err = posix_acl_listxattr(inode, &buffer, &remaining_size);
1460 if (err)
1461 return err;
1462
1463 read_lock(&xattrs->lock);
1464 for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
1465 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1466
1467 /* skip "trusted." attributes for unprivileged callers */
1468 if (!trusted && xattr_is_trusted(xattr->name))
1469 continue;
1470
1471 err = xattr_list_one(&buffer, &remaining_size, xattr->name);
1472 if (err)
1473 break;
1474 }
1475 read_unlock(&xattrs->lock);
1476
1477 return err ? err : size - remaining_size;
1478}
1479
1480/**
1481 * rbtree_simple_xattr_less - compare two xattr rbtree nodes
1482 * @new_node: new node
1483 * @node: current node
1484 *
1485 * Compare the xattr attached to @new_node with the xattr attached to @node.
1486 * Note that this function technically tolerates duplicate entries.
1487 *
1488 * Return: True if insertion point in the rbtree is found.
1489 */
1490static bool rbtree_simple_xattr_less(struct rb_node *new_node,
1491 const struct rb_node *node)
1492{
1493 return rbtree_simple_xattr_node_cmp(new_node, node) < 0;
1494}
1495
1496/**
1497 * simple_xattr_add - add xattr objects
1498 * @xattrs: the header of the xattr object
1499 * @new_xattr: the xattr object to add
1500 *
1501 * Add an xattr object to @xattrs. This assumes no replacement or removal
1502 * of matching xattrs is wanted. Should only be called during inode
1503 * initialization when a few distinct initial xattrs are supposed to be set.
1504 */
1505void simple_xattr_add(struct simple_xattrs *xattrs,
1506 struct simple_xattr *new_xattr)
1507{
1508 write_lock(&xattrs->lock);
1509 rb_add(&new_xattr->rb_node, &xattrs->rb_root, rbtree_simple_xattr_less);
1510 write_unlock(&xattrs->lock);
1511}
1512
1513/**
1514 * simple_xattrs_init - initialize new xattr header
1515 * @xattrs: header to initialize
1516 *
1517 * Initialize relevant fields of a an xattr header.
1518 */
1519void simple_xattrs_init(struct simple_xattrs *xattrs)
1520{
1521 xattrs->rb_root = RB_ROOT;
1522 rwlock_init(&xattrs->lock);
1523}
1524
1525/**
1526 * simple_xattrs_free - free xattrs
1527 * @xattrs: xattr header whose xattrs to destroy
1528 * @freed_space: approximate number of bytes of memory freed from @xattrs
1529 *
1530 * Destroy all xattrs in @xattr. When this is called no one can hold a
1531 * reference to any of the xattrs anymore.
1532 */
1533void simple_xattrs_free(struct simple_xattrs *xattrs, size_t *freed_space)
1534{
1535 struct rb_node *rbp;
1536
1537 if (freed_space)
1538 *freed_space = 0;
1539 rbp = rb_first(&xattrs->rb_root);
1540 while (rbp) {
1541 struct simple_xattr *xattr;
1542 struct rb_node *rbp_next;
1543
1544 rbp_next = rb_next(rbp);
1545 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1546 rb_erase(&xattr->rb_node, &xattrs->rb_root);
1547 if (freed_space)
1548 *freed_space += simple_xattr_space(xattr->name,
1549 xattr->size);
1550 simple_xattr_free(xattr);
1551 rbp = rbp_next;
1552 }
1553}