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1/*
2 * This file is part of UBIFS.
3 *
4 * Copyright (C) 2006-2008 Nokia Corporation.
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * more details.
14 *
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 51
17 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 *
19 * Authors: Artem Bityutskiy (Битюцкий Артём)
20 * Adrian Hunter
21 */
22
23/*
24 * This file implements UBIFS extended attributes support.
25 *
26 * Extended attributes are implemented as regular inodes with attached data,
27 * which limits extended attribute size to UBIFS block size (4KiB). Names of
28 * extended attributes are described by extended attribute entries (xentries),
29 * which are almost identical to directory entries, but have different key type.
30 *
31 * In other words, the situation with extended attributes is very similar to
32 * directories. Indeed, any inode (but of course not xattr inodes) may have a
33 * number of associated xentries, just like directory inodes have associated
34 * directory entries. Extended attribute entries store the name of the extended
35 * attribute, the host inode number, and the extended attribute inode number.
36 * Similarly, direntries store the name, the parent and the target inode
37 * numbers. Thus, most of the common UBIFS mechanisms may be re-used for
38 * extended attributes.
39 *
40 * The number of extended attributes is not limited, but there is Linux
41 * limitation on the maximum possible size of the list of all extended
42 * attributes associated with an inode (%XATTR_LIST_MAX), so UBIFS makes sure
43 * the sum of all extended attribute names of the inode does not exceed that
44 * limit.
45 *
46 * Extended attributes are synchronous, which means they are written to the
47 * flash media synchronously and there is no write-back for extended attribute
48 * inodes. The extended attribute values are not stored in compressed form on
49 * the media.
50 *
51 * Since extended attributes are represented by regular inodes, they are cached
52 * in the VFS inode cache. The xentries are cached in the LNC cache (see
53 * tnc.c).
54 *
55 * ACL support is not implemented.
56 */
57
58#include "ubifs.h"
59#include <linux/fs.h>
60#include <linux/slab.h>
61#include <linux/xattr.h>
62
63/*
64 * Limit the number of extended attributes per inode so that the total size
65 * (@xattr_size) is guaranteeded to fit in an 'unsigned int'.
66 */
67#define MAX_XATTRS_PER_INODE 65535
68
69/*
70 * Extended attribute type constants.
71 *
72 * USER_XATTR: user extended attribute ("user.*")
73 * TRUSTED_XATTR: trusted extended attribute ("trusted.*)
74 * SECURITY_XATTR: security extended attribute ("security.*")
75 */
76enum {
77 USER_XATTR,
78 TRUSTED_XATTR,
79 SECURITY_XATTR,
80};
81
82static const struct inode_operations empty_iops;
83static const struct file_operations empty_fops;
84
85/**
86 * create_xattr - create an extended attribute.
87 * @c: UBIFS file-system description object
88 * @host: host inode
89 * @nm: extended attribute name
90 * @value: extended attribute value
91 * @size: size of extended attribute value
92 *
93 * This is a helper function which creates an extended attribute of name @nm
94 * and value @value for inode @host. The host inode is also updated on flash
95 * because the ctime and extended attribute accounting data changes. This
96 * function returns zero in case of success and a negative error code in case
97 * of failure.
98 */
99static int create_xattr(struct ubifs_info *c, struct inode *host,
100 const struct qstr *nm, const void *value, int size)
101{
102 int err, names_len;
103 struct inode *inode;
104 struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
105 struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
106 .new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
107 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
108
109 if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE) {
110 ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
111 host->i_ino, host_ui->xattr_cnt);
112 return -ENOSPC;
113 }
114 /*
115 * Linux limits the maximum size of the extended attribute names list
116 * to %XATTR_LIST_MAX. This means we should not allow creating more
117 * extended attributes if the name list becomes larger. This limitation
118 * is artificial for UBIFS, though.
119 */
120 names_len = host_ui->xattr_names + host_ui->xattr_cnt + nm->len + 1;
121 if (names_len > XATTR_LIST_MAX) {
122 ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
123 host->i_ino, names_len, XATTR_LIST_MAX);
124 return -ENOSPC;
125 }
126
127 err = ubifs_budget_space(c, &req);
128 if (err)
129 return err;
130
131 inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
132 if (IS_ERR(inode)) {
133 err = PTR_ERR(inode);
134 goto out_budg;
135 }
136
137 /* Re-define all operations to be "nothing" */
138 inode->i_mapping->a_ops = &empty_aops;
139 inode->i_op = &empty_iops;
140 inode->i_fop = &empty_fops;
141
142 inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME | S_NOQUOTA;
143 ui = ubifs_inode(inode);
144 ui->xattr = 1;
145 ui->flags |= UBIFS_XATTR_FL;
146 ui->data = kmemdup(value, size, GFP_NOFS);
147 if (!ui->data) {
148 err = -ENOMEM;
149 goto out_free;
150 }
151 inode->i_size = ui->ui_size = size;
152 ui->data_len = size;
153
154 mutex_lock(&host_ui->ui_mutex);
155 host->i_ctime = ubifs_current_time(host);
156 host_ui->xattr_cnt += 1;
157 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
158 host_ui->xattr_size += CALC_XATTR_BYTES(size);
159 host_ui->xattr_names += nm->len;
160
161 err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
162 if (err)
163 goto out_cancel;
164 mutex_unlock(&host_ui->ui_mutex);
165
166 ubifs_release_budget(c, &req);
167 insert_inode_hash(inode);
168 iput(inode);
169 return 0;
170
171out_cancel:
172 host_ui->xattr_cnt -= 1;
173 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
174 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
175 mutex_unlock(&host_ui->ui_mutex);
176out_free:
177 make_bad_inode(inode);
178 iput(inode);
179out_budg:
180 ubifs_release_budget(c, &req);
181 return err;
182}
183
184/**
185 * change_xattr - change an extended attribute.
186 * @c: UBIFS file-system description object
187 * @host: host inode
188 * @inode: extended attribute inode
189 * @value: extended attribute value
190 * @size: size of extended attribute value
191 *
192 * This helper function changes the value of extended attribute @inode with new
193 * data from @value. Returns zero in case of success and a negative error code
194 * in case of failure.
195 */
196static int change_xattr(struct ubifs_info *c, struct inode *host,
197 struct inode *inode, const void *value, int size)
198{
199 int err;
200 struct ubifs_inode *host_ui = ubifs_inode(host);
201 struct ubifs_inode *ui = ubifs_inode(inode);
202 void *buf = NULL;
203 struct ubifs_budget_req req = { .dirtied_ino = 2,
204 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
205
206 ubifs_assert(ui->data_len == inode->i_size);
207 err = ubifs_budget_space(c, &req);
208 if (err)
209 return err;
210
211 buf = kmemdup(value, size, GFP_NOFS);
212 if (!buf) {
213 err = -ENOMEM;
214 goto out_free;
215 }
216 mutex_lock(&ui->ui_mutex);
217 kfree(ui->data);
218 ui->data = buf;
219 inode->i_size = ui->ui_size = size;
220 ui->data_len = size;
221 mutex_unlock(&ui->ui_mutex);
222
223 mutex_lock(&host_ui->ui_mutex);
224 host->i_ctime = ubifs_current_time(host);
225 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
226 host_ui->xattr_size += CALC_XATTR_BYTES(size);
227
228 /*
229 * It is important to write the host inode after the xattr inode
230 * because if the host inode gets synchronized (via 'fsync()'), then
231 * the extended attribute inode gets synchronized, because it goes
232 * before the host inode in the write-buffer.
233 */
234 err = ubifs_jnl_change_xattr(c, inode, host);
235 if (err)
236 goto out_cancel;
237 mutex_unlock(&host_ui->ui_mutex);
238
239 ubifs_release_budget(c, &req);
240 return 0;
241
242out_cancel:
243 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
244 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
245 mutex_unlock(&host_ui->ui_mutex);
246 make_bad_inode(inode);
247out_free:
248 ubifs_release_budget(c, &req);
249 return err;
250}
251
252/**
253 * check_namespace - check extended attribute name-space.
254 * @nm: extended attribute name
255 *
256 * This function makes sure the extended attribute name belongs to one of the
257 * supported extended attribute name-spaces. Returns name-space index in case
258 * of success and a negative error code in case of failure.
259 */
260static int check_namespace(const struct qstr *nm)
261{
262 int type;
263
264 if (nm->len > UBIFS_MAX_NLEN)
265 return -ENAMETOOLONG;
266
267 if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
268 XATTR_TRUSTED_PREFIX_LEN)) {
269 if (nm->name[XATTR_TRUSTED_PREFIX_LEN] == '\0')
270 return -EINVAL;
271 type = TRUSTED_XATTR;
272 } else if (!strncmp(nm->name, XATTR_USER_PREFIX,
273 XATTR_USER_PREFIX_LEN)) {
274 if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
275 return -EINVAL;
276 type = USER_XATTR;
277 } else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
278 XATTR_SECURITY_PREFIX_LEN)) {
279 if (nm->name[XATTR_SECURITY_PREFIX_LEN] == '\0')
280 return -EINVAL;
281 type = SECURITY_XATTR;
282 } else
283 return -EOPNOTSUPP;
284
285 return type;
286}
287
288static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
289{
290 struct inode *inode;
291
292 inode = ubifs_iget(c->vfs_sb, inum);
293 if (IS_ERR(inode)) {
294 ubifs_err(c, "dead extended attribute entry, error %d",
295 (int)PTR_ERR(inode));
296 return inode;
297 }
298 if (ubifs_inode(inode)->xattr)
299 return inode;
300 ubifs_err(c, "corrupt extended attribute entry");
301 iput(inode);
302 return ERR_PTR(-EINVAL);
303}
304
305static int setxattr(struct inode *host, const char *name, const void *value,
306 size_t size, int flags)
307{
308 struct inode *inode;
309 struct ubifs_info *c = host->i_sb->s_fs_info;
310 struct qstr nm = QSTR_INIT(name, strlen(name));
311 struct ubifs_dent_node *xent;
312 union ubifs_key key;
313 int err, type;
314
315 ubifs_assert(inode_is_locked(host));
316
317 if (size > UBIFS_MAX_INO_DATA)
318 return -ERANGE;
319
320 type = check_namespace(&nm);
321 if (type < 0)
322 return type;
323
324 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
325 if (!xent)
326 return -ENOMEM;
327
328 /*
329 * The extended attribute entries are stored in LNC, so multiple
330 * look-ups do not involve reading the flash.
331 */
332 xent_key_init(c, &key, host->i_ino, &nm);
333 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
334 if (err) {
335 if (err != -ENOENT)
336 goto out_free;
337
338 if (flags & XATTR_REPLACE)
339 /* We are asked not to create the xattr */
340 err = -ENODATA;
341 else
342 err = create_xattr(c, host, &nm, value, size);
343 goto out_free;
344 }
345
346 if (flags & XATTR_CREATE) {
347 /* We are asked not to replace the xattr */
348 err = -EEXIST;
349 goto out_free;
350 }
351
352 inode = iget_xattr(c, le64_to_cpu(xent->inum));
353 if (IS_ERR(inode)) {
354 err = PTR_ERR(inode);
355 goto out_free;
356 }
357
358 err = change_xattr(c, host, inode, value, size);
359 iput(inode);
360
361out_free:
362 kfree(xent);
363 return err;
364}
365
366int ubifs_setxattr(struct dentry *dentry, const char *name,
367 const void *value, size_t size, int flags)
368{
369 dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
370 name, d_inode(dentry)->i_ino, dentry, size);
371
372 return setxattr(d_inode(dentry), name, value, size, flags);
373}
374
375ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
376 size_t size)
377{
378 struct inode *inode, *host = d_inode(dentry);
379 struct ubifs_info *c = host->i_sb->s_fs_info;
380 struct qstr nm = QSTR_INIT(name, strlen(name));
381 struct ubifs_inode *ui;
382 struct ubifs_dent_node *xent;
383 union ubifs_key key;
384 int err;
385
386 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
387 host->i_ino, dentry, size);
388
389 err = check_namespace(&nm);
390 if (err < 0)
391 return err;
392
393 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
394 if (!xent)
395 return -ENOMEM;
396
397 xent_key_init(c, &key, host->i_ino, &nm);
398 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
399 if (err) {
400 if (err == -ENOENT)
401 err = -ENODATA;
402 goto out_unlock;
403 }
404
405 inode = iget_xattr(c, le64_to_cpu(xent->inum));
406 if (IS_ERR(inode)) {
407 err = PTR_ERR(inode);
408 goto out_unlock;
409 }
410
411 ui = ubifs_inode(inode);
412 ubifs_assert(inode->i_size == ui->data_len);
413 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
414
415 mutex_lock(&ui->ui_mutex);
416 if (buf) {
417 /* If @buf is %NULL we are supposed to return the length */
418 if (ui->data_len > size) {
419 ubifs_err(c, "buffer size %zd, xattr len %d",
420 size, ui->data_len);
421 err = -ERANGE;
422 goto out_iput;
423 }
424
425 memcpy(buf, ui->data, ui->data_len);
426 }
427 err = ui->data_len;
428
429out_iput:
430 mutex_unlock(&ui->ui_mutex);
431 iput(inode);
432out_unlock:
433 kfree(xent);
434 return err;
435}
436
437ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
438{
439 union ubifs_key key;
440 struct inode *host = d_inode(dentry);
441 struct ubifs_info *c = host->i_sb->s_fs_info;
442 struct ubifs_inode *host_ui = ubifs_inode(host);
443 struct ubifs_dent_node *xent, *pxent = NULL;
444 int err, len, written = 0;
445 struct qstr nm = { .name = NULL };
446
447 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
448 dentry, size);
449
450 len = host_ui->xattr_names + host_ui->xattr_cnt;
451 if (!buffer)
452 /*
453 * We should return the minimum buffer size which will fit a
454 * null-terminated list of all the extended attribute names.
455 */
456 return len;
457
458 if (len > size)
459 return -ERANGE;
460
461 lowest_xent_key(c, &key, host->i_ino);
462 while (1) {
463 int type;
464
465 xent = ubifs_tnc_next_ent(c, &key, &nm);
466 if (IS_ERR(xent)) {
467 err = PTR_ERR(xent);
468 break;
469 }
470
471 nm.name = xent->name;
472 nm.len = le16_to_cpu(xent->nlen);
473
474 type = check_namespace(&nm);
475 if (unlikely(type < 0)) {
476 err = type;
477 break;
478 }
479
480 /* Show trusted namespace only for "power" users */
481 if (type != TRUSTED_XATTR || capable(CAP_SYS_ADMIN)) {
482 memcpy(buffer + written, nm.name, nm.len + 1);
483 written += nm.len + 1;
484 }
485
486 kfree(pxent);
487 pxent = xent;
488 key_read(c, &xent->key, &key);
489 }
490
491 kfree(pxent);
492 if (err != -ENOENT) {
493 ubifs_err(c, "cannot find next direntry, error %d", err);
494 return err;
495 }
496
497 ubifs_assert(written <= size);
498 return written;
499}
500
501static int remove_xattr(struct ubifs_info *c, struct inode *host,
502 struct inode *inode, const struct qstr *nm)
503{
504 int err;
505 struct ubifs_inode *host_ui = ubifs_inode(host);
506 struct ubifs_inode *ui = ubifs_inode(inode);
507 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
508 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
509
510 ubifs_assert(ui->data_len == inode->i_size);
511
512 err = ubifs_budget_space(c, &req);
513 if (err)
514 return err;
515
516 mutex_lock(&host_ui->ui_mutex);
517 host->i_ctime = ubifs_current_time(host);
518 host_ui->xattr_cnt -= 1;
519 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
520 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
521 host_ui->xattr_names -= nm->len;
522
523 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
524 if (err)
525 goto out_cancel;
526 mutex_unlock(&host_ui->ui_mutex);
527
528 ubifs_release_budget(c, &req);
529 return 0;
530
531out_cancel:
532 host_ui->xattr_cnt += 1;
533 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
534 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
535 mutex_unlock(&host_ui->ui_mutex);
536 ubifs_release_budget(c, &req);
537 make_bad_inode(inode);
538 return err;
539}
540
541int ubifs_removexattr(struct dentry *dentry, const char *name)
542{
543 struct inode *inode, *host = d_inode(dentry);
544 struct ubifs_info *c = host->i_sb->s_fs_info;
545 struct qstr nm = QSTR_INIT(name, strlen(name));
546 struct ubifs_dent_node *xent;
547 union ubifs_key key;
548 int err;
549
550 dbg_gen("xattr '%s', ino %lu ('%pd')", name,
551 host->i_ino, dentry);
552 ubifs_assert(inode_is_locked(host));
553
554 err = check_namespace(&nm);
555 if (err < 0)
556 return err;
557
558 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
559 if (!xent)
560 return -ENOMEM;
561
562 xent_key_init(c, &key, host->i_ino, &nm);
563 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
564 if (err) {
565 if (err == -ENOENT)
566 err = -ENODATA;
567 goto out_free;
568 }
569
570 inode = iget_xattr(c, le64_to_cpu(xent->inum));
571 if (IS_ERR(inode)) {
572 err = PTR_ERR(inode);
573 goto out_free;
574 }
575
576 ubifs_assert(inode->i_nlink == 1);
577 clear_nlink(inode);
578 err = remove_xattr(c, host, inode, &nm);
579 if (err)
580 set_nlink(inode, 1);
581
582 /* If @i_nlink is 0, 'iput()' will delete the inode */
583 iput(inode);
584
585out_free:
586 kfree(xent);
587 return err;
588}
589
590static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
591 void *fs_info)
592{
593 const struct xattr *xattr;
594 char *name;
595 int err = 0;
596
597 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
598 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
599 strlen(xattr->name) + 1, GFP_NOFS);
600 if (!name) {
601 err = -ENOMEM;
602 break;
603 }
604 strcpy(name, XATTR_SECURITY_PREFIX);
605 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
606 err = setxattr(inode, name, xattr->value, xattr->value_len, 0);
607 kfree(name);
608 if (err < 0)
609 break;
610 }
611
612 return err;
613}
614
615int ubifs_init_security(struct inode *dentry, struct inode *inode,
616 const struct qstr *qstr)
617{
618 int err;
619
620 err = security_inode_init_security(inode, dentry, qstr,
621 &init_xattrs, 0);
622 if (err) {
623 struct ubifs_info *c = dentry->i_sb->s_fs_info;
624 ubifs_err(c, "cannot initialize security for inode %lu, error %d",
625 inode->i_ino, err);
626 }
627 return err;
628}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * This file is part of UBIFS.
4 *
5 * Copyright (C) 2006-2008 Nokia Corporation.
6 *
7 * Authors: Artem Bityutskiy (Битюцкий Артём)
8 * Adrian Hunter
9 */
10
11/*
12 * This file implements UBIFS extended attributes support.
13 *
14 * Extended attributes are implemented as regular inodes with attached data,
15 * which limits extended attribute size to UBIFS block size (4KiB). Names of
16 * extended attributes are described by extended attribute entries (xentries),
17 * which are almost identical to directory entries, but have different key type.
18 *
19 * In other words, the situation with extended attributes is very similar to
20 * directories. Indeed, any inode (but of course not xattr inodes) may have a
21 * number of associated xentries, just like directory inodes have associated
22 * directory entries. Extended attribute entries store the name of the extended
23 * attribute, the host inode number, and the extended attribute inode number.
24 * Similarly, direntries store the name, the parent and the target inode
25 * numbers. Thus, most of the common UBIFS mechanisms may be re-used for
26 * extended attributes.
27 *
28 * The number of extended attributes is not limited, but there is Linux
29 * limitation on the maximum possible size of the list of all extended
30 * attributes associated with an inode (%XATTR_LIST_MAX), so UBIFS makes sure
31 * the sum of all extended attribute names of the inode does not exceed that
32 * limit.
33 *
34 * Extended attributes are synchronous, which means they are written to the
35 * flash media synchronously and there is no write-back for extended attribute
36 * inodes. The extended attribute values are not stored in compressed form on
37 * the media.
38 *
39 * Since extended attributes are represented by regular inodes, they are cached
40 * in the VFS inode cache. The xentries are cached in the LNC cache (see
41 * tnc.c).
42 *
43 * ACL support is not implemented.
44 */
45
46#include "ubifs.h"
47#include <linux/fs.h>
48#include <linux/slab.h>
49#include <linux/xattr.h>
50
51/*
52 * Extended attribute type constants.
53 *
54 * USER_XATTR: user extended attribute ("user.*")
55 * TRUSTED_XATTR: trusted extended attribute ("trusted.*)
56 * SECURITY_XATTR: security extended attribute ("security.*")
57 */
58enum {
59 USER_XATTR,
60 TRUSTED_XATTR,
61 SECURITY_XATTR,
62};
63
64static const struct inode_operations empty_iops;
65static const struct file_operations empty_fops;
66
67/**
68 * create_xattr - create an extended attribute.
69 * @c: UBIFS file-system description object
70 * @host: host inode
71 * @nm: extended attribute name
72 * @value: extended attribute value
73 * @size: size of extended attribute value
74 *
75 * This is a helper function which creates an extended attribute of name @nm
76 * and value @value for inode @host. The host inode is also updated on flash
77 * because the ctime and extended attribute accounting data changes. This
78 * function returns zero in case of success and a negative error code in case
79 * of failure.
80 */
81static int create_xattr(struct ubifs_info *c, struct inode *host,
82 const struct fscrypt_name *nm, const void *value, int size)
83{
84 int err, names_len;
85 struct inode *inode;
86 struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
87 struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
88 .new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
89 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
90
91 if (host_ui->xattr_cnt >= ubifs_xattr_max_cnt(c)) {
92 ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
93 host->i_ino, host_ui->xattr_cnt);
94 return -ENOSPC;
95 }
96 /*
97 * Linux limits the maximum size of the extended attribute names list
98 * to %XATTR_LIST_MAX. This means we should not allow creating more
99 * extended attributes if the name list becomes larger. This limitation
100 * is artificial for UBIFS, though.
101 */
102 names_len = host_ui->xattr_names + host_ui->xattr_cnt + fname_len(nm) + 1;
103 if (names_len > XATTR_LIST_MAX) {
104 ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
105 host->i_ino, names_len, XATTR_LIST_MAX);
106 return -ENOSPC;
107 }
108
109 err = ubifs_budget_space(c, &req);
110 if (err)
111 return err;
112
113 inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO, true);
114 if (IS_ERR(inode)) {
115 err = PTR_ERR(inode);
116 goto out_budg;
117 }
118
119 /* Re-define all operations to be "nothing" */
120 inode->i_mapping->a_ops = &empty_aops;
121 inode->i_op = &empty_iops;
122 inode->i_fop = &empty_fops;
123
124 inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME;
125 ui = ubifs_inode(inode);
126 ui->xattr = 1;
127 ui->flags |= UBIFS_XATTR_FL;
128 ui->data = kmemdup(value, size, GFP_NOFS);
129 if (!ui->data) {
130 err = -ENOMEM;
131 goto out_free;
132 }
133 inode->i_size = ui->ui_size = size;
134 ui->data_len = size;
135
136 mutex_lock(&host_ui->ui_mutex);
137 host->i_ctime = current_time(host);
138 host_ui->xattr_cnt += 1;
139 host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
140 host_ui->xattr_size += CALC_XATTR_BYTES(size);
141 host_ui->xattr_names += fname_len(nm);
142
143 /*
144 * We handle UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT here because we
145 * have to set the UBIFS_CRYPT_FL flag on the host inode.
146 * To avoid multiple updates of the same inode in the same operation,
147 * let's do it here.
148 */
149 if (strcmp(fname_name(nm), UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
150 host_ui->flags |= UBIFS_CRYPT_FL;
151
152 err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
153 if (err)
154 goto out_cancel;
155 ubifs_set_inode_flags(host);
156 mutex_unlock(&host_ui->ui_mutex);
157
158 ubifs_release_budget(c, &req);
159 insert_inode_hash(inode);
160 iput(inode);
161 return 0;
162
163out_cancel:
164 host_ui->xattr_cnt -= 1;
165 host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
166 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
167 host_ui->xattr_names -= fname_len(nm);
168 host_ui->flags &= ~UBIFS_CRYPT_FL;
169 mutex_unlock(&host_ui->ui_mutex);
170out_free:
171 make_bad_inode(inode);
172 iput(inode);
173out_budg:
174 ubifs_release_budget(c, &req);
175 return err;
176}
177
178/**
179 * change_xattr - change an extended attribute.
180 * @c: UBIFS file-system description object
181 * @host: host inode
182 * @inode: extended attribute inode
183 * @value: extended attribute value
184 * @size: size of extended attribute value
185 *
186 * This helper function changes the value of extended attribute @inode with new
187 * data from @value. Returns zero in case of success and a negative error code
188 * in case of failure.
189 */
190static int change_xattr(struct ubifs_info *c, struct inode *host,
191 struct inode *inode, const void *value, int size)
192{
193 int err;
194 struct ubifs_inode *host_ui = ubifs_inode(host);
195 struct ubifs_inode *ui = ubifs_inode(inode);
196 void *buf = NULL;
197 int old_size;
198 struct ubifs_budget_req req = { .dirtied_ino = 2,
199 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
200
201 ubifs_assert(c, ui->data_len == inode->i_size);
202 err = ubifs_budget_space(c, &req);
203 if (err)
204 return err;
205
206 buf = kmemdup(value, size, GFP_NOFS);
207 if (!buf) {
208 err = -ENOMEM;
209 goto out_free;
210 }
211 kfree(ui->data);
212 ui->data = buf;
213 inode->i_size = ui->ui_size = size;
214 old_size = ui->data_len;
215 ui->data_len = size;
216
217 mutex_lock(&host_ui->ui_mutex);
218 host->i_ctime = current_time(host);
219 host_ui->xattr_size -= CALC_XATTR_BYTES(old_size);
220 host_ui->xattr_size += CALC_XATTR_BYTES(size);
221
222 /*
223 * It is important to write the host inode after the xattr inode
224 * because if the host inode gets synchronized (via 'fsync()'), then
225 * the extended attribute inode gets synchronized, because it goes
226 * before the host inode in the write-buffer.
227 */
228 err = ubifs_jnl_change_xattr(c, inode, host);
229 if (err)
230 goto out_cancel;
231 mutex_unlock(&host_ui->ui_mutex);
232
233 ubifs_release_budget(c, &req);
234 return 0;
235
236out_cancel:
237 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
238 host_ui->xattr_size += CALC_XATTR_BYTES(old_size);
239 mutex_unlock(&host_ui->ui_mutex);
240 make_bad_inode(inode);
241out_free:
242 ubifs_release_budget(c, &req);
243 return err;
244}
245
246static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
247{
248 struct inode *inode;
249
250 inode = ubifs_iget(c->vfs_sb, inum);
251 if (IS_ERR(inode)) {
252 ubifs_err(c, "dead extended attribute entry, error %d",
253 (int)PTR_ERR(inode));
254 return inode;
255 }
256 if (ubifs_inode(inode)->xattr)
257 return inode;
258 ubifs_err(c, "corrupt extended attribute entry");
259 iput(inode);
260 return ERR_PTR(-EINVAL);
261}
262
263int ubifs_xattr_set(struct inode *host, const char *name, const void *value,
264 size_t size, int flags, bool check_lock)
265{
266 struct inode *inode;
267 struct ubifs_info *c = host->i_sb->s_fs_info;
268 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
269 struct ubifs_dent_node *xent;
270 union ubifs_key key;
271 int err;
272
273 if (check_lock)
274 ubifs_assert(c, inode_is_locked(host));
275
276 if (size > UBIFS_MAX_INO_DATA)
277 return -ERANGE;
278
279 if (fname_len(&nm) > UBIFS_MAX_NLEN)
280 return -ENAMETOOLONG;
281
282 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
283 if (!xent)
284 return -ENOMEM;
285
286 down_write(&ubifs_inode(host)->xattr_sem);
287 /*
288 * The extended attribute entries are stored in LNC, so multiple
289 * look-ups do not involve reading the flash.
290 */
291 xent_key_init(c, &key, host->i_ino, &nm);
292 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
293 if (err) {
294 if (err != -ENOENT)
295 goto out_free;
296
297 if (flags & XATTR_REPLACE)
298 /* We are asked not to create the xattr */
299 err = -ENODATA;
300 else
301 err = create_xattr(c, host, &nm, value, size);
302 goto out_free;
303 }
304
305 if (flags & XATTR_CREATE) {
306 /* We are asked not to replace the xattr */
307 err = -EEXIST;
308 goto out_free;
309 }
310
311 inode = iget_xattr(c, le64_to_cpu(xent->inum));
312 if (IS_ERR(inode)) {
313 err = PTR_ERR(inode);
314 goto out_free;
315 }
316
317 err = change_xattr(c, host, inode, value, size);
318 iput(inode);
319
320out_free:
321 up_write(&ubifs_inode(host)->xattr_sem);
322 kfree(xent);
323 return err;
324}
325
326ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf,
327 size_t size)
328{
329 struct inode *inode;
330 struct ubifs_info *c = host->i_sb->s_fs_info;
331 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
332 struct ubifs_inode *ui;
333 struct ubifs_dent_node *xent;
334 union ubifs_key key;
335 int err;
336
337 if (fname_len(&nm) > UBIFS_MAX_NLEN)
338 return -ENAMETOOLONG;
339
340 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
341 if (!xent)
342 return -ENOMEM;
343
344 down_read(&ubifs_inode(host)->xattr_sem);
345 xent_key_init(c, &key, host->i_ino, &nm);
346 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
347 if (err) {
348 if (err == -ENOENT)
349 err = -ENODATA;
350 goto out_cleanup;
351 }
352
353 inode = iget_xattr(c, le64_to_cpu(xent->inum));
354 if (IS_ERR(inode)) {
355 err = PTR_ERR(inode);
356 goto out_cleanup;
357 }
358
359 ui = ubifs_inode(inode);
360 ubifs_assert(c, inode->i_size == ui->data_len);
361 ubifs_assert(c, ubifs_inode(host)->xattr_size > ui->data_len);
362
363 if (buf) {
364 /* If @buf is %NULL we are supposed to return the length */
365 if (ui->data_len > size) {
366 err = -ERANGE;
367 goto out_iput;
368 }
369
370 memcpy(buf, ui->data, ui->data_len);
371 }
372 err = ui->data_len;
373
374out_iput:
375 iput(inode);
376out_cleanup:
377 up_read(&ubifs_inode(host)->xattr_sem);
378 kfree(xent);
379 return err;
380}
381
382static bool xattr_visible(const char *name)
383{
384 /* File encryption related xattrs are for internal use only */
385 if (strcmp(name, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
386 return false;
387
388 /* Show trusted namespace only for "power" users */
389 if (strncmp(name, XATTR_TRUSTED_PREFIX,
390 XATTR_TRUSTED_PREFIX_LEN) == 0 && !capable(CAP_SYS_ADMIN))
391 return false;
392
393 return true;
394}
395
396ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
397{
398 union ubifs_key key;
399 struct inode *host = d_inode(dentry);
400 struct ubifs_info *c = host->i_sb->s_fs_info;
401 struct ubifs_inode *host_ui = ubifs_inode(host);
402 struct ubifs_dent_node *xent, *pxent = NULL;
403 int err, len, written = 0;
404 struct fscrypt_name nm = {0};
405
406 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
407 dentry, size);
408
409 down_read(&host_ui->xattr_sem);
410 len = host_ui->xattr_names + host_ui->xattr_cnt;
411 if (!buffer) {
412 /*
413 * We should return the minimum buffer size which will fit a
414 * null-terminated list of all the extended attribute names.
415 */
416 err = len;
417 goto out_err;
418 }
419
420 if (len > size) {
421 err = -ERANGE;
422 goto out_err;
423 }
424
425 lowest_xent_key(c, &key, host->i_ino);
426 while (1) {
427 xent = ubifs_tnc_next_ent(c, &key, &nm);
428 if (IS_ERR(xent)) {
429 err = PTR_ERR(xent);
430 break;
431 }
432
433 fname_name(&nm) = xent->name;
434 fname_len(&nm) = le16_to_cpu(xent->nlen);
435
436 if (xattr_visible(xent->name)) {
437 memcpy(buffer + written, fname_name(&nm), fname_len(&nm) + 1);
438 written += fname_len(&nm) + 1;
439 }
440
441 kfree(pxent);
442 pxent = xent;
443 key_read(c, &xent->key, &key);
444 }
445 kfree(pxent);
446 up_read(&host_ui->xattr_sem);
447
448 if (err != -ENOENT) {
449 ubifs_err(c, "cannot find next direntry, error %d", err);
450 return err;
451 }
452
453 ubifs_assert(c, written <= size);
454 return written;
455
456out_err:
457 up_read(&host_ui->xattr_sem);
458 return err;
459}
460
461static int remove_xattr(struct ubifs_info *c, struct inode *host,
462 struct inode *inode, const struct fscrypt_name *nm)
463{
464 int err;
465 struct ubifs_inode *host_ui = ubifs_inode(host);
466 struct ubifs_inode *ui = ubifs_inode(inode);
467 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
468 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
469
470 ubifs_assert(c, ui->data_len == inode->i_size);
471
472 err = ubifs_budget_space(c, &req);
473 if (err)
474 return err;
475
476 mutex_lock(&host_ui->ui_mutex);
477 host->i_ctime = current_time(host);
478 host_ui->xattr_cnt -= 1;
479 host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
480 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
481 host_ui->xattr_names -= fname_len(nm);
482
483 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
484 if (err)
485 goto out_cancel;
486 mutex_unlock(&host_ui->ui_mutex);
487
488 ubifs_release_budget(c, &req);
489 return 0;
490
491out_cancel:
492 host_ui->xattr_cnt += 1;
493 host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
494 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
495 host_ui->xattr_names += fname_len(nm);
496 mutex_unlock(&host_ui->ui_mutex);
497 ubifs_release_budget(c, &req);
498 make_bad_inode(inode);
499 return err;
500}
501
502int ubifs_purge_xattrs(struct inode *host)
503{
504 union ubifs_key key;
505 struct ubifs_info *c = host->i_sb->s_fs_info;
506 struct ubifs_dent_node *xent, *pxent = NULL;
507 struct inode *xino;
508 struct fscrypt_name nm = {0};
509 int err;
510
511 if (ubifs_inode(host)->xattr_cnt <= ubifs_xattr_max_cnt(c))
512 return 0;
513
514 ubifs_warn(c, "inode %lu has too many xattrs, doing a non-atomic deletion",
515 host->i_ino);
516
517 down_write(&ubifs_inode(host)->xattr_sem);
518 lowest_xent_key(c, &key, host->i_ino);
519 while (1) {
520 xent = ubifs_tnc_next_ent(c, &key, &nm);
521 if (IS_ERR(xent)) {
522 err = PTR_ERR(xent);
523 break;
524 }
525
526 fname_name(&nm) = xent->name;
527 fname_len(&nm) = le16_to_cpu(xent->nlen);
528
529 xino = ubifs_iget(c->vfs_sb, le64_to_cpu(xent->inum));
530 if (IS_ERR(xino)) {
531 err = PTR_ERR(xino);
532 ubifs_err(c, "dead directory entry '%s', error %d",
533 xent->name, err);
534 ubifs_ro_mode(c, err);
535 kfree(pxent);
536 kfree(xent);
537 goto out_err;
538 }
539
540 ubifs_assert(c, ubifs_inode(xino)->xattr);
541
542 clear_nlink(xino);
543 err = remove_xattr(c, host, xino, &nm);
544 if (err) {
545 kfree(pxent);
546 kfree(xent);
547 iput(xino);
548 ubifs_err(c, "cannot remove xattr, error %d", err);
549 goto out_err;
550 }
551
552 iput(xino);
553
554 kfree(pxent);
555 pxent = xent;
556 key_read(c, &xent->key, &key);
557 }
558 kfree(pxent);
559 up_write(&ubifs_inode(host)->xattr_sem);
560
561 if (err != -ENOENT) {
562 ubifs_err(c, "cannot find next direntry, error %d", err);
563 return err;
564 }
565
566 return 0;
567
568out_err:
569 up_write(&ubifs_inode(host)->xattr_sem);
570 return err;
571}
572
573/**
574 * ubifs_evict_xattr_inode - Evict an xattr inode.
575 * @c: UBIFS file-system description object
576 * @xattr_inum: xattr inode number
577 *
578 * When an inode that hosts xattrs is being removed we have to make sure
579 * that cached inodes of the xattrs also get removed from the inode cache
580 * otherwise we'd waste memory. This function looks up an inode from the
581 * inode cache and clears the link counter such that iput() will evict
582 * the inode.
583 */
584void ubifs_evict_xattr_inode(struct ubifs_info *c, ino_t xattr_inum)
585{
586 struct inode *inode;
587
588 inode = ilookup(c->vfs_sb, xattr_inum);
589 if (inode) {
590 clear_nlink(inode);
591 iput(inode);
592 }
593}
594
595static int ubifs_xattr_remove(struct inode *host, const char *name)
596{
597 struct inode *inode;
598 struct ubifs_info *c = host->i_sb->s_fs_info;
599 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
600 struct ubifs_dent_node *xent;
601 union ubifs_key key;
602 int err;
603
604 ubifs_assert(c, inode_is_locked(host));
605
606 if (fname_len(&nm) > UBIFS_MAX_NLEN)
607 return -ENAMETOOLONG;
608
609 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
610 if (!xent)
611 return -ENOMEM;
612
613 down_write(&ubifs_inode(host)->xattr_sem);
614 xent_key_init(c, &key, host->i_ino, &nm);
615 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
616 if (err) {
617 if (err == -ENOENT)
618 err = -ENODATA;
619 goto out_free;
620 }
621
622 inode = iget_xattr(c, le64_to_cpu(xent->inum));
623 if (IS_ERR(inode)) {
624 err = PTR_ERR(inode);
625 goto out_free;
626 }
627
628 ubifs_assert(c, inode->i_nlink == 1);
629 clear_nlink(inode);
630 err = remove_xattr(c, host, inode, &nm);
631 if (err)
632 set_nlink(inode, 1);
633
634 /* If @i_nlink is 0, 'iput()' will delete the inode */
635 iput(inode);
636
637out_free:
638 up_write(&ubifs_inode(host)->xattr_sem);
639 kfree(xent);
640 return err;
641}
642
643#ifdef CONFIG_UBIFS_FS_SECURITY
644static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
645 void *fs_info)
646{
647 const struct xattr *xattr;
648 char *name;
649 int err = 0;
650
651 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
652 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
653 strlen(xattr->name) + 1, GFP_NOFS);
654 if (!name) {
655 err = -ENOMEM;
656 break;
657 }
658 strcpy(name, XATTR_SECURITY_PREFIX);
659 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
660 /*
661 * creating a new inode without holding the inode rwsem,
662 * no need to check whether inode is locked.
663 */
664 err = ubifs_xattr_set(inode, name, xattr->value,
665 xattr->value_len, 0, false);
666 kfree(name);
667 if (err < 0)
668 break;
669 }
670
671 return err;
672}
673
674int ubifs_init_security(struct inode *dentry, struct inode *inode,
675 const struct qstr *qstr)
676{
677 int err;
678
679 err = security_inode_init_security(inode, dentry, qstr,
680 &init_xattrs, NULL);
681 if (err) {
682 struct ubifs_info *c = dentry->i_sb->s_fs_info;
683 ubifs_err(c, "cannot initialize security for inode %lu, error %d",
684 inode->i_ino, err);
685 }
686 return err;
687}
688#endif
689
690static int xattr_get(const struct xattr_handler *handler,
691 struct dentry *dentry, struct inode *inode,
692 const char *name, void *buffer, size_t size)
693{
694 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
695 inode->i_ino, dentry, size);
696
697 name = xattr_full_name(handler, name);
698 return ubifs_xattr_get(inode, name, buffer, size);
699}
700
701static int xattr_set(const struct xattr_handler *handler,
702 struct user_namespace *mnt_userns,
703 struct dentry *dentry, struct inode *inode,
704 const char *name, const void *value,
705 size_t size, int flags)
706{
707 dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
708 name, inode->i_ino, dentry, size);
709
710 name = xattr_full_name(handler, name);
711
712 if (value)
713 return ubifs_xattr_set(inode, name, value, size, flags, true);
714 else
715 return ubifs_xattr_remove(inode, name);
716}
717
718static const struct xattr_handler ubifs_user_xattr_handler = {
719 .prefix = XATTR_USER_PREFIX,
720 .get = xattr_get,
721 .set = xattr_set,
722};
723
724static const struct xattr_handler ubifs_trusted_xattr_handler = {
725 .prefix = XATTR_TRUSTED_PREFIX,
726 .get = xattr_get,
727 .set = xattr_set,
728};
729
730#ifdef CONFIG_UBIFS_FS_SECURITY
731static const struct xattr_handler ubifs_security_xattr_handler = {
732 .prefix = XATTR_SECURITY_PREFIX,
733 .get = xattr_get,
734 .set = xattr_set,
735};
736#endif
737
738const struct xattr_handler *ubifs_xattr_handlers[] = {
739 &ubifs_user_xattr_handler,
740 &ubifs_trusted_xattr_handler,
741#ifdef CONFIG_UBIFS_FS_SECURITY
742 &ubifs_security_xattr_handler,
743#endif
744 NULL
745};