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(error: -EIO);
64 return ERR_PTR(error: -EOPNOTSUPP);
65 }
66 for_each_xattr_handler(handlers, handler) {
67 const char *n;
68
69 n = strcmp_prefix(a: *name, a_prefix: xattr_prefix(handler));
70 if (n) {
71 if (!handler->prefix ^ !*n) {
72 if (*n)
73 continue;
74 return ERR_PTR(error: -EINVAL);
75 }
76 *name = n;
77 return handler;
78 }
79 }
80 return ERR_PTR(error: -EOPNOTSUPP);
81}
82
83/**
84 * may_write_xattr - check whether inode allows writing xattr
85 * @idmap: idmap of the mount the inode was found from
86 * @inode: the inode on which to set an xattr
87 *
88 * Check whether the inode allows writing xattrs. Specifically, we can never
89 * set or remove an extended attribute on a read-only filesystem or on an
90 * immutable / append-only inode.
91 *
92 * We also need to ensure that the inode has a mapping in the mount to
93 * not risk writing back invalid i_{g,u}id values.
94 *
95 * Return: On success zero is returned. On error a negative errno is returned.
96 */
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: &name);
194 if (IS_ERR(ptr: handler))
195 return PTR_ERR(ptr: handler);
196 if (!handler->set)
197 return -EOPNOTSUPP;
198 if (size == 0)
199 value = ""; /* empty EA, do not remove */
200 return handler->set(handler, idmap, dentry, inode, name, value,
201 size, flags);
202}
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_rwsem 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, name: suffix, value,
252 size, flags);
253 if (!error)
254 fsnotify_xattr(dentry);
255 }
256 }
257
258 return error;
259}
260
261/**
262 * __vfs_setxattr_locked - set an extended attribute while holding the inode
263 * lock
264 *
265 * @idmap: idmap of the mount of the target inode
266 * @dentry: object to perform setxattr on
267 * @name: xattr name to set
268 * @value: value to set @name to
269 * @size: size of @value
270 * @flags: flags to pass into filesystem operations
271 * @delegated_inode: on return, will contain an inode pointer that
272 * a delegation was broken on, NULL if none.
273 */
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, ivalue: &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: &delegated_inode);
327 if (!error)
328 goto retry_deleg;
329 }
330 if (value != orig_value)
331 kfree(objp: 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: &buffer, alloc: false);
347 goto out_noalloc;
348 }
349
350 len = security_inode_getsecurity(idmap, inode, name, buffer: &buffer,
351 alloc: true);
352 if (len < 0)
353 return len;
354 if (size < len) {
355 len = -ERANGE;
356 goto out;
357 }
358 memcpy(to: value, from: buffer, len);
359out:
360 kfree(objp: 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: &name);
389 if (IS_ERR(ptr: handler))
390 return PTR_ERR(ptr: handler);
391 if (!handler->get)
392 return -EOPNOTSUPP;
393 error = handler->get(handler, dentry, inode, name, NULL, 0);
394 if (error < 0)
395 return error;
396
397 if (!value || (error > xattr_size)) {
398 value = krealloc(*xattr_value, error + 1, flags);
399 if (!value)
400 return -ENOMEM;
401 memset(s: value, c: 0, n: 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: &name);
419 if (IS_ERR(ptr: handler))
420 return PTR_ERR(ptr: handler);
421 if (!handler->get)
422 return -EOPNOTSUPP;
423 return handler->get(handler, dentry, inode, name, value, size);
424}
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, name: suffix, value,
446 size);
447 /*
448 * Only overwrite the return value if a security module
449 * is actually active.
450 */
451 if (ret == -EOPNOTSUPP)
452 goto nolsm;
453 return ret;
454 }
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, buffer: list, buffer_size: 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: &name);
514 if (IS_ERR(ptr: handler))
515 return PTR_ERR(ptr: handler);
516 if (!handler->set)
517 return -EOPNOTSUPP;
518 return handler->set(handler, idmap, dentry, inode, name, NULL, 0,
519 XATTR_REPLACE);
520}
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: &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(dst: kname->name, src: name,
592 count: 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(kname: 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(ptr: ctx->kvalue)) {
621 error = PTR_ERR(ptr: 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(name: ctx->kname->name))
633 return do_set_acl(idmap, dentry, acl_name: ctx->kname->name,
634 kvalue: ctx->kvalue, size: 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(file: f);
643
644 if (!error) {
645 audit_file(file: f);
646 error = do_setxattr(idmap: file_mnt_idmap(file: f), dentry: f->f_path.dentry, ctx);
647 mnt_drop_write_file(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, name: filename, flags: lookup_flags, path: &path, NULL);
661 if (error)
662 goto out;
663 error = mnt_want_write(mnt: path.mnt);
664 if (!error) {
665 error = do_setxattr(idmap: mnt_idmap(mnt: path.mnt), dentry: path.dentry, ctx);
666 mnt_drop_write(mnt: path.mnt);
667 }
668 path_put(&path);
669 if (retry_estale(error, flags: lookup_flags)) {
670 lookup_flags |= LOOKUP_REVAL;
671 goto retry;
672 }
673
674out:
675 putname(name: 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: &ctx);
702 if (error)
703 return error;
704
705 filename = getname_maybe_null(name: pathname, flags: at_flags);
706 if (!filename && dfd >= 0) {
707 CLASS(fd, f)(fd: dfd);
708 if (fd_empty(f))
709 error = -EBADF;
710 else
711 error = file_setxattr(fd_file(f), ctx: &ctx);
712 } else {
713 error = filename_setxattr(dfd, filename, lookup_flags, ctx: &ctx);
714 }
715 kvfree(addr: 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(dst: &args, ksize: sizeof(args), src: 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), size: args.size,
740 flags: 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, at_flags: 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(dfd: 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(name: kname))
785 error = do_get_acl(idmap, dentry: d, acl_name: kname, kvalue, size: 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(to: ctx->value, from: kvalue, n: 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(addr: kvalue);
798 return error;
799}
800
801ssize_t file_getxattr(struct file *f, struct kernel_xattr_ctx *ctx)
802{
803 audit_file(file: f);
804 return do_getxattr(idmap: file_mnt_idmap(file: f), d: 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, name: filename, flags: lookup_flags, path: &path, NULL);
815 if (error)
816 goto out;
817 error = do_getxattr(idmap: mnt_idmap(mnt: path.mnt), d: path.dentry, ctx);
818 path_put(&path);
819 if (retry_estale(error, flags: lookup_flags)) {
820 lookup_flags |= LOOKUP_REVAL;
821 goto retry;
822 }
823out:
824 putname(name: 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: &kname, name);
846 if (error)
847 return error;
848
849 filename = getname_maybe_null(name: pathname, flags: at_flags);
850 if (!filename && dfd >= 0) {
851 CLASS(fd, f)(fd: dfd);
852 if (fd_empty(f))
853 return -EBADF;
854 return file_getxattr(fd_file(f), ctx: &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: &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(dst: &args, ksize: sizeof(args), src: 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), size: 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, at_flags: 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(dfd: 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(to: list, from: klist, n: 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(addr: 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(file: f);
943 return listxattr(d: 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, name: filename, flags: lookup_flags, path: &path, NULL);
956 if (error)
957 goto out;
958 error = listxattr(d: path.dentry, list, size);
959 path_put(&path);
960 if (retry_estale(error, flags: lookup_flags)) {
961 lookup_flags |= LOOKUP_REVAL;
962 goto retry;
963 }
964out:
965 putname(name: 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(name: pathname, flags: at_flags);
980 if (!filename) {
981 CLASS(fd, f)(fd: 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, at_flags: 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(dfd: 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, dentry: d, acl_name: 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(file: f);
1029
1030 if (!error) {
1031 audit_file(file: f);
1032 error = removexattr(idmap: file_mnt_idmap(file: f),
1033 d: f->f_path.dentry, name: kname->name);
1034 mnt_drop_write_file(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, name: filename, flags: lookup_flags, path: &path, NULL);
1048 if (error)
1049 goto out;
1050 error = mnt_want_write(mnt: path.mnt);
1051 if (!error) {
1052 error = removexattr(idmap: mnt_idmap(mnt: path.mnt), d: path.dentry, name: kname->name);
1053 mnt_drop_write(mnt: path.mnt);
1054 }
1055 path_put(&path);
1056 if (retry_estale(error, flags: lookup_flags)) {
1057 lookup_flags |= LOOKUP_REVAL;
1058 goto retry;
1059 }
1060out:
1061 putname(name: 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: &kname, name);
1077 if (error)
1078 return error;
1079
1080 filename = getname_maybe_null(name: pathname, flags: at_flags);
1081 if (!filename) {
1082 CLASS(fd, f)(fd: dfd);
1083 if (fd_empty(f))
1084 return -EBADF;
1085 return file_removexattr(fd_file(f), kname: &kname);
1086 }
1087 lookup_flags = (at_flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
1088 return filename_removexattr(dfd, filename, lookup_flags, kname: &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, at_flags: 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(dfd: 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(to: *buffer, from: 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: &buffer, remaining_size: &remaining_size, name: 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(objp: xattr->name);
1214 kvfree(addr: 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(to: new_xattr->value, from: value, len: 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(key: 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(key: name, tree: &xattrs->rb_root, cmp: 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(to: buffer, from: xattr->value, len: 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(error: -ENOMEM);
1361
1362 new_xattr->name = kstrdup(s: name, GFP_KERNEL_ACCOUNT);
1363 if (!new_xattr->name) {
1364 simple_xattr_free(xattr: new_xattr);
1365 return ERR_PTR(error: -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(key: name, node: *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(victim: &old_xattr->rb_node,
1393 new: &new_xattr->rb_node, root: &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(node: &new_xattr->rb_node, parent, rb_link: 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(xattr: new_xattr);
1423 return ERR_PTR(error: 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
1431static bool xattr_is_maclabel(const char *name)
1432{
1433 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
1434
1435 return !strncmp(name, XATTR_SECURITY_PREFIX,
1436 XATTR_SECURITY_PREFIX_LEN) &&
1437 security_ismaclabel(name: suffix);
1438}
1439
1440/**
1441 * simple_xattr_list - list all xattr objects
1442 * @inode: inode from which to get the xattrs
1443 * @xattrs: the header of the xattr object
1444 * @buffer: the buffer to store all xattrs into
1445 * @size: the size of @buffer
1446 *
1447 * List all xattrs associated with @inode. If @buffer is NULL we returned
1448 * the required size of the buffer. If @buffer is provided we store the
1449 * xattrs value into it provided it is big enough.
1450 *
1451 * Note, the number of xattr names that can be listed with listxattr(2) is
1452 * limited to XATTR_LIST_MAX aka 65536 bytes. If a larger buffer is passed
1453 * then vfs_listxattr() caps it to XATTR_LIST_MAX and if more xattr names
1454 * are found it will return -E2BIG.
1455 *
1456 * Return: On success the required size or the size of the copied xattrs is
1457 * returned. On error a negative error code is returned.
1458 */
1459ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
1460 char *buffer, size_t size)
1461{
1462 bool trusted = ns_capable_noaudit(ns: &init_user_ns, CAP_SYS_ADMIN);
1463 struct simple_xattr *xattr;
1464 struct rb_node *rbp;
1465 ssize_t remaining_size = size;
1466 int err = 0;
1467
1468 err = posix_acl_listxattr(inode, buffer: &buffer, remaining_size: &remaining_size);
1469 if (err)
1470 return err;
1471
1472 err = security_inode_listsecurity(inode, buffer, buffer_size: remaining_size);
1473 if (err < 0)
1474 return err;
1475
1476 if (buffer) {
1477 if (remaining_size < err)
1478 return -ERANGE;
1479 buffer += err;
1480 }
1481 remaining_size -= err;
1482 err = 0;
1483
1484 read_lock(&xattrs->lock);
1485 for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
1486 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1487
1488 /* skip "trusted." attributes for unprivileged callers */
1489 if (!trusted && xattr_is_trusted(name: xattr->name))
1490 continue;
1491
1492 /* skip MAC labels; these are provided by LSM above */
1493 if (xattr_is_maclabel(name: xattr->name))
1494 continue;
1495
1496 err = xattr_list_one(buffer: &buffer, remaining_size: &remaining_size, name: xattr->name);
1497 if (err)
1498 break;
1499 }
1500 read_unlock(&xattrs->lock);
1501
1502 return err ? err : size - remaining_size;
1503}
1504
1505/**
1506 * rbtree_simple_xattr_less - compare two xattr rbtree nodes
1507 * @new_node: new node
1508 * @node: current node
1509 *
1510 * Compare the xattr attached to @new_node with the xattr attached to @node.
1511 * Note that this function technically tolerates duplicate entries.
1512 *
1513 * Return: True if insertion point in the rbtree is found.
1514 */
1515static bool rbtree_simple_xattr_less(struct rb_node *new_node,
1516 const struct rb_node *node)
1517{
1518 return rbtree_simple_xattr_node_cmp(new_node, node) < 0;
1519}
1520
1521/**
1522 * simple_xattr_add - add xattr objects
1523 * @xattrs: the header of the xattr object
1524 * @new_xattr: the xattr object to add
1525 *
1526 * Add an xattr object to @xattrs. This assumes no replacement or removal
1527 * of matching xattrs is wanted. Should only be called during inode
1528 * initialization when a few distinct initial xattrs are supposed to be set.
1529 */
1530void simple_xattr_add(struct simple_xattrs *xattrs,
1531 struct simple_xattr *new_xattr)
1532{
1533 write_lock(&xattrs->lock);
1534 rb_add(node: &new_xattr->rb_node, tree: &xattrs->rb_root, less: rbtree_simple_xattr_less);
1535 write_unlock(&xattrs->lock);
1536}
1537
1538/**
1539 * simple_xattrs_init - initialize new xattr header
1540 * @xattrs: header to initialize
1541 *
1542 * Initialize relevant fields of a an xattr header.
1543 */
1544void simple_xattrs_init(struct simple_xattrs *xattrs)
1545{
1546 xattrs->rb_root = RB_ROOT;
1547 rwlock_init(&xattrs->lock);
1548}
1549
1550/**
1551 * simple_xattrs_free - free xattrs
1552 * @xattrs: xattr header whose xattrs to destroy
1553 * @freed_space: approximate number of bytes of memory freed from @xattrs
1554 *
1555 * Destroy all xattrs in @xattr. When this is called no one can hold a
1556 * reference to any of the xattrs anymore.
1557 */
1558void simple_xattrs_free(struct simple_xattrs *xattrs, size_t *freed_space)
1559{
1560 struct rb_node *rbp;
1561
1562 if (freed_space)
1563 *freed_space = 0;
1564 rbp = rb_first(&xattrs->rb_root);
1565 while (rbp) {
1566 struct simple_xattr *xattr;
1567 struct rb_node *rbp_next;
1568
1569 rbp_next = rb_next(rbp);
1570 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1571 rb_erase(&xattr->rb_node, &xattrs->rb_root);
1572 if (freed_space)
1573 *freed_space += simple_xattr_space(name: xattr->name,
1574 size: xattr->size);
1575 simple_xattr_free(xattr);
1576 rbp = rbp_next;
1577 }
1578}
1579