xattr_handler: pass dentry and inode as separate arguments of ->get()
[deliverable/linux.git] / fs / ubifs / xattr.c
CommitLineData
1e51764a
AB
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
073aaa1b 58#include "ubifs.h"
7dcda1c9 59#include <linux/fs.h>
5a0e3ad6 60#include <linux/slab.h>
1e51764a 61#include <linux/xattr.h>
1e51764a
AB
62
63/*
64 * Limit the number of extended attributes per inode so that the total size
c78c7e35 65 * (@xattr_size) is guaranteeded to fit in an 'unsigned int'.
1e51764a
AB
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
14ffd5d0
SD
82static const struct inode_operations empty_iops;
83static const struct file_operations empty_fops;
1e51764a
AB
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{
fee1756d 102 int err, names_len;
1e51764a
AB
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,
5acd6ff8
ZS
106 .new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
107 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
1e51764a 108
fee1756d 109 if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE) {
235c362b 110 ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
fee1756d 111 host->i_ino, host_ui->xattr_cnt);
1e51764a 112 return -ENOSPC;
fee1756d 113 }
1e51764a
AB
114 /*
115 * Linux limits the maximum size of the extended attribute names list
c78c7e35 116 * to %XATTR_LIST_MAX. This means we should not allow creating more
1e51764a
AB
117 * extended attributes if the name list becomes larger. This limitation
118 * is artificial for UBIFS, though.
119 */
fee1756d
SN
120 names_len = host_ui->xattr_names + host_ui->xattr_cnt + nm->len + 1;
121 if (names_len > XATTR_LIST_MAX) {
235c362b 122 ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
fee1756d 123 host->i_ino, names_len, XATTR_LIST_MAX);
1e51764a 124 return -ENOSPC;
fee1756d 125 }
1e51764a
AB
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
1e51764a 137 /* Re-define all operations to be "nothing" */
7dcda1c9 138 inode->i_mapping->a_ops = &empty_aops;
14ffd5d0
SD
139 inode->i_op = &empty_iops;
140 inode->i_fop = &empty_fops;
1e51764a
AB
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;
eaecf43a 146 ui->data = kmemdup(value, size, GFP_NOFS);
1e51764a
AB
147 if (!ui->data) {
148 err = -ENOMEM;
c78c7e35 149 goto out_free;
1e51764a 150 }
c78c7e35
AB
151 inode->i_size = ui->ui_size = size;
152 ui->data_len = size;
153
154 mutex_lock(&host_ui->ui_mutex);
1e51764a
AB
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
1e51764a
AB
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);
1e51764a 175 mutex_unlock(&host_ui->ui_mutex);
c78c7e35 176out_free:
1e51764a
AB
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);
ab92a20b 202 void *buf = NULL;
1e51764a 203 struct ubifs_budget_req req = { .dirtied_ino = 2,
5acd6ff8 204 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
1e51764a
AB
205
206 ubifs_assert(ui->data_len == inode->i_size);
207 err = ubifs_budget_space(c, &req);
208 if (err)
209 return err;
210
ab92a20b
DY
211 buf = kmemdup(value, size, GFP_NOFS);
212 if (!buf) {
1e51764a 213 err = -ENOMEM;
c78c7e35 214 goto out_free;
1e51764a 215 }
ab92a20b
DY
216 mutex_lock(&ui->ui_mutex);
217 kfree(ui->data);
218 ui->data = buf;
1e51764a
AB
219 inode->i_size = ui->ui_size = size;
220 ui->data_len = size;
ab92a20b 221 mutex_unlock(&ui->ui_mutex);
1e51764a 222
c78c7e35
AB
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
1e51764a
AB
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);
1e51764a 245 mutex_unlock(&host_ui->ui_mutex);
c78c7e35
AB
246 make_bad_inode(inode);
247out_free:
1e51764a
AB
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)) {
4fdd1d51 269 if (nm->name[XATTR_TRUSTED_PREFIX_LEN] == '\0')
1e51764a
AB
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)) {
4fdd1d51 279 if (nm->name[XATTR_SECURITY_PREFIX_LEN] == '\0')
1e51764a
AB
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)) {
235c362b 294 ubifs_err(c, "dead extended attribute entry, error %d",
1e51764a
AB
295 (int)PTR_ERR(inode));
296 return inode;
297 }
298 if (ubifs_inode(inode)->xattr)
299 return inode;
235c362b 300 ubifs_err(c, "corrupt extended attribute entry");
1e51764a
AB
301 iput(inode);
302 return ERR_PTR(-EINVAL);
303}
304
895d9db2
SN
305static int setxattr(struct inode *host, const char *name, const void *value,
306 size_t size, int flags)
1e51764a 307{
895d9db2 308 struct inode *inode;
1e51764a 309 struct ubifs_info *c = host->i_sb->s_fs_info;
26fe5750 310 struct qstr nm = QSTR_INIT(name, strlen(name));
1e51764a
AB
311 struct ubifs_dent_node *xent;
312 union ubifs_key key;
313 int err, type;
314
5955102c 315 ubifs_assert(inode_is_locked(host));
1e51764a
AB
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
895d9db2
SN
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",
2b0143b5 370 name, d_inode(dentry)->i_ino, dentry, size);
895d9db2 371
2b0143b5 372 return setxattr(d_inode(dentry), name, value, size, flags);
895d9db2
SN
373}
374
1e51764a
AB
375ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
376 size_t size)
377{
2b0143b5 378 struct inode *inode, *host = d_inode(dentry);
1e51764a 379 struct ubifs_info *c = host->i_sb->s_fs_info;
26fe5750 380 struct qstr nm = QSTR_INIT(name, strlen(name));
1e51764a
AB
381 struct ubifs_inode *ui;
382 struct ubifs_dent_node *xent;
383 union ubifs_key key;
384 int err;
385
4cb2a01d
AV
386 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
387 host->i_ino, dentry, size);
1e51764a
AB
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
1e51764a
AB
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
ab92a20b 415 mutex_lock(&ui->ui_mutex);
1e51764a
AB
416 if (buf) {
417 /* If @buf is %NULL we are supposed to return the length */
418 if (ui->data_len > size) {
235c362b 419 ubifs_err(c, "buffer size %zd, xattr len %d",
a6aae4dd 420 size, ui->data_len);
1e51764a
AB
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:
ab92a20b 430 mutex_unlock(&ui->ui_mutex);
1e51764a
AB
431 iput(inode);
432out_unlock:
1e51764a
AB
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;
2b0143b5 440 struct inode *host = d_inode(dentry);
1e51764a
AB
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
4cb2a01d
AV
447 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
448 dentry, size);
1e51764a
AB
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);
1e51764a
AB
462 while (1) {
463 int type;
464
465 xent = ubifs_tnc_next_ent(c, &key, &nm);
8d47aef4 466 if (IS_ERR(xent)) {
1e51764a
AB
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 }
1e51764a
AB
490
491 kfree(pxent);
492 if (err != -ENOENT) {
235c362b 493 ubifs_err(c, "cannot find next direntry, error %d", err);
1e51764a
AB
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);
5acd6ff8
ZS
507 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
508 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
1e51764a
AB
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{
2b0143b5 543 struct inode *inode, *host = d_inode(dentry);
1e51764a 544 struct ubifs_info *c = host->i_sb->s_fs_info;
26fe5750 545 struct qstr nm = QSTR_INIT(name, strlen(name));
1e51764a
AB
546 struct ubifs_dent_node *xent;
547 union ubifs_key key;
548 int err;
549
4cb2a01d
AV
550 dbg_gen("xattr '%s', ino %lu ('%pd')", name,
551 host->i_ino, dentry);
5955102c 552 ubifs_assert(inode_is_locked(host));
1e51764a
AB
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);
6d6b77f1 577 clear_nlink(inode);
1e51764a
AB
578 err = remove_xattr(c, host, inode, &nm);
579 if (err)
bfe86848 580 set_nlink(inode, 1);
1e51764a
AB
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}
d7f0b70d 589
d7f0b70d
SN
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
d7f0b70d
SN
620 err = security_inode_init_security(inode, dentry, qstr,
621 &init_xattrs, 0);
235c362b
SY
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",
fee1756d 625 inode->i_ino, err);
235c362b 626 }
d7f0b70d
SN
627 return err;
628}
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