aboutsummaryrefslogtreecommitdiffstats
path: root/fs/ubifs/xattr.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/ubifs/xattr.c')
-rw-r--r--fs/ubifs/xattr.c581
1 files changed, 581 insertions, 0 deletions
diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c
new file mode 100644
index 000000000000..1388a078e1a9
--- /dev/null
+++ b/fs/ubifs/xattr.c
@@ -0,0 +1,581 @@
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 <linux/xattr.h>
59#include <linux/posix_acl_xattr.h>
60#include "ubifs.h"
61
62/*
63 * Limit the number of extended attributes per inode so that the total size
64 * (xattr_size) is guaranteeded to fit in an 'unsigned int'.
65 */
66#define MAX_XATTRS_PER_INODE 65535
67
68/*
69 * Extended attribute type constants.
70 *
71 * USER_XATTR: user extended attribute ("user.*")
72 * TRUSTED_XATTR: trusted extended attribute ("trusted.*)
73 * SECURITY_XATTR: security extended attribute ("security.*")
74 */
75enum {
76 USER_XATTR,
77 TRUSTED_XATTR,
78 SECURITY_XATTR,
79};
80
81static struct inode_operations none_inode_operations;
82static struct address_space_operations none_address_operations;
83static struct file_operations none_file_operations;
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;
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 = size, .dirtied_ino = 1,
107 .dirtied_ino_d = host_ui->data_len};
108
109 if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE)
110 return -ENOSPC;
111 /*
112 * Linux limits the maximum size of the extended attribute names list
113 * to %XATTR_LIST_MAX. This means we should not allow creating more*
114 * extended attributes if the name list becomes larger. This limitation
115 * is artificial for UBIFS, though.
116 */
117 if (host_ui->xattr_names + host_ui->xattr_cnt +
118 nm->len + 1 > XATTR_LIST_MAX)
119 return -ENOSPC;
120
121 err = ubifs_budget_space(c, &req);
122 if (err)
123 return err;
124
125 inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
126 if (IS_ERR(inode)) {
127 err = PTR_ERR(inode);
128 goto out_budg;
129 }
130
131 mutex_lock(&host_ui->ui_mutex);
132 /* Re-define all operations to be "nothing" */
133 inode->i_mapping->a_ops = &none_address_operations;
134 inode->i_op = &none_inode_operations;
135 inode->i_fop = &none_file_operations;
136
137 inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME | S_NOQUOTA;
138 ui = ubifs_inode(inode);
139 ui->xattr = 1;
140 ui->flags |= UBIFS_XATTR_FL;
141 ui->data = kmalloc(size, GFP_NOFS);
142 if (!ui->data) {
143 err = -ENOMEM;
144 goto out_unlock;
145 }
146
147 memcpy(ui->data, value, size);
148 host->i_ctime = ubifs_current_time(host);
149 host_ui->xattr_cnt += 1;
150 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
151 host_ui->xattr_size += CALC_XATTR_BYTES(size);
152 host_ui->xattr_names += nm->len;
153
154 /*
155 * We do not use i_size_write() because nobody can race with us as we
156 * are holding host @host->i_mutex - every xattr operation for this
157 * inode is serialized by it.
158 */
159 inode->i_size = ui->ui_size = size;
160 ui->data_len = size;
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);
175out_unlock:
176 mutex_unlock(&host_ui->ui_mutex);
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 struct ubifs_budget_req req = { .dirtied_ino = 2,
203 .dirtied_ino_d = size + host_ui->data_len };
204
205 ubifs_assert(ui->data_len == inode->i_size);
206 err = ubifs_budget_space(c, &req);
207 if (err)
208 return err;
209
210 mutex_lock(&host_ui->ui_mutex);
211 host->i_ctime = ubifs_current_time(host);
212 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
213 host_ui->xattr_size += CALC_XATTR_BYTES(size);
214
215 kfree(ui->data);
216 ui->data = kmalloc(size, GFP_NOFS);
217 if (!ui->data) {
218 err = -ENOMEM;
219 goto out_unlock;
220 }
221
222 memcpy(ui->data, value, size);
223 inode->i_size = ui->ui_size = size;
224 ui->data_len = size;
225
226 /*
227 * It is important to write the host inode after the xattr inode
228 * because if the host inode gets synchronized (via 'fsync()'), then
229 * the extended attribute inode gets synchronized, because it goes
230 * before the host inode in the write-buffer.
231 */
232 err = ubifs_jnl_change_xattr(c, inode, host);
233 if (err)
234 goto out_cancel;
235 mutex_unlock(&host_ui->ui_mutex);
236
237 ubifs_release_budget(c, &req);
238 return 0;
239
240out_cancel:
241 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
242 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
243 make_bad_inode(inode);
244out_unlock:
245 mutex_unlock(&host_ui->ui_mutex);
246 ubifs_release_budget(c, &req);
247 return err;
248}
249
250/**
251 * check_namespace - check extended attribute name-space.
252 * @nm: extended attribute name
253 *
254 * This function makes sure the extended attribute name belongs to one of the
255 * supported extended attribute name-spaces. Returns name-space index in case
256 * of success and a negative error code in case of failure.
257 */
258static int check_namespace(const struct qstr *nm)
259{
260 int type;
261
262 if (nm->len > UBIFS_MAX_NLEN)
263 return -ENAMETOOLONG;
264
265 if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
266 XATTR_TRUSTED_PREFIX_LEN)) {
267 if (nm->name[sizeof(XATTR_TRUSTED_PREFIX) - 1] == '\0')
268 return -EINVAL;
269 type = TRUSTED_XATTR;
270 } else if (!strncmp(nm->name, XATTR_USER_PREFIX,
271 XATTR_USER_PREFIX_LEN)) {
272 if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
273 return -EINVAL;
274 type = USER_XATTR;
275 } else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
276 XATTR_SECURITY_PREFIX_LEN)) {
277 if (nm->name[sizeof(XATTR_SECURITY_PREFIX) - 1] == '\0')
278 return -EINVAL;
279 type = SECURITY_XATTR;
280 } else
281 return -EOPNOTSUPP;
282
283 return type;
284}
285
286static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
287{
288 struct inode *inode;
289
290 inode = ubifs_iget(c->vfs_sb, inum);
291 if (IS_ERR(inode)) {
292 ubifs_err("dead extended attribute entry, error %d",
293 (int)PTR_ERR(inode));
294 return inode;
295 }
296 if (ubifs_inode(inode)->xattr)
297 return inode;
298 ubifs_err("corrupt extended attribute entry");
299 iput(inode);
300 return ERR_PTR(-EINVAL);
301}
302
303int ubifs_setxattr(struct dentry *dentry, const char *name,
304 const void *value, size_t size, int flags)
305{
306 struct inode *inode, *host = dentry->d_inode;
307 struct ubifs_info *c = host->i_sb->s_fs_info;
308 struct qstr nm = { .name = name, .len = strlen(name) };
309 struct ubifs_dent_node *xent;
310 union ubifs_key key;
311 int err, type;
312
313 dbg_gen("xattr '%s', host ino %lu ('%.*s'), size %zd", name,
314 host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
315
316 if (size > UBIFS_MAX_INO_DATA)
317 return -ERANGE;
318
319 type = check_namespace(&nm);
320 if (type < 0)
321 return type;
322
323 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
324 if (!xent)
325 return -ENOMEM;
326
327 /*
328 * The extended attribute entries are stored in LNC, so multiple
329 * look-ups do not involve reading the flash.
330 */
331 xent_key_init(c, &key, host->i_ino, &nm);
332 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
333 if (err) {
334 if (err != -ENOENT)
335 goto out_free;
336
337 if (flags & XATTR_REPLACE)
338 /* We are asked not to create the xattr */
339 err = -ENODATA;
340 else
341 err = create_xattr(c, host, &nm, value, size);
342 goto out_free;
343 }
344
345 if (flags & XATTR_CREATE) {
346 /* We are asked not to replace the xattr */
347 err = -EEXIST;
348 goto out_free;
349 }
350
351 inode = iget_xattr(c, le64_to_cpu(xent->inum));
352 if (IS_ERR(inode)) {
353 err = PTR_ERR(inode);
354 goto out_free;
355 }
356
357 err = change_xattr(c, host, inode, value, size);
358 iput(inode);
359
360out_free:
361 kfree(xent);
362 return err;
363}
364
365ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
366 size_t size)
367{
368 struct inode *inode, *host = dentry->d_inode;
369 struct ubifs_info *c = host->i_sb->s_fs_info;
370 struct qstr nm = { .name = name, .len = strlen(name) };
371 struct ubifs_inode *ui;
372 struct ubifs_dent_node *xent;
373 union ubifs_key key;
374 int err;
375
376 dbg_gen("xattr '%s', ino %lu ('%.*s'), buf size %zd", name,
377 host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
378
379 err = check_namespace(&nm);
380 if (err < 0)
381 return err;
382
383 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
384 if (!xent)
385 return -ENOMEM;
386
387 mutex_lock(&host->i_mutex);
388 xent_key_init(c, &key, host->i_ino, &nm);
389 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
390 if (err) {
391 if (err == -ENOENT)
392 err = -ENODATA;
393 goto out_unlock;
394 }
395
396 inode = iget_xattr(c, le64_to_cpu(xent->inum));
397 if (IS_ERR(inode)) {
398 err = PTR_ERR(inode);
399 goto out_unlock;
400 }
401
402 ui = ubifs_inode(inode);
403 ubifs_assert(inode->i_size == ui->data_len);
404 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
405
406 if (buf) {
407 /* If @buf is %NULL we are supposed to return the length */
408 if (ui->data_len > size) {
409 dbg_err("buffer size %zd, xattr len %d",
410 size, ui->data_len);
411 err = -ERANGE;
412 goto out_iput;
413 }
414
415 memcpy(buf, ui->data, ui->data_len);
416 }
417 err = ui->data_len;
418
419out_iput:
420 iput(inode);
421out_unlock:
422 mutex_unlock(&host->i_mutex);
423 kfree(xent);
424 return err;
425}
426
427ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
428{
429 union ubifs_key key;
430 struct inode *host = dentry->d_inode;
431 struct ubifs_info *c = host->i_sb->s_fs_info;
432 struct ubifs_inode *host_ui = ubifs_inode(host);
433 struct ubifs_dent_node *xent, *pxent = NULL;
434 int err, len, written = 0;
435 struct qstr nm = { .name = NULL };
436
437 dbg_gen("ino %lu ('%.*s'), buffer size %zd", host->i_ino,
438 dentry->d_name.len, dentry->d_name.name, size);
439
440 len = host_ui->xattr_names + host_ui->xattr_cnt;
441 if (!buffer)
442 /*
443 * We should return the minimum buffer size which will fit a
444 * null-terminated list of all the extended attribute names.
445 */
446 return len;
447
448 if (len > size)
449 return -ERANGE;
450
451 lowest_xent_key(c, &key, host->i_ino);
452
453 mutex_lock(&host->i_mutex);
454 while (1) {
455 int type;
456
457 xent = ubifs_tnc_next_ent(c, &key, &nm);
458 if (unlikely(IS_ERR(xent))) {
459 err = PTR_ERR(xent);
460 break;
461 }
462
463 nm.name = xent->name;
464 nm.len = le16_to_cpu(xent->nlen);
465
466 type = check_namespace(&nm);
467 if (unlikely(type < 0)) {
468 err = type;
469 break;
470 }
471
472 /* Show trusted namespace only for "power" users */
473 if (type != TRUSTED_XATTR || capable(CAP_SYS_ADMIN)) {
474 memcpy(buffer + written, nm.name, nm.len + 1);
475 written += nm.len + 1;
476 }
477
478 kfree(pxent);
479 pxent = xent;
480 key_read(c, &xent->key, &key);
481 }
482 mutex_unlock(&host->i_mutex);
483
484 kfree(pxent);
485 if (err != -ENOENT) {
486 ubifs_err("cannot find next direntry, error %d", err);
487 return err;
488 }
489
490 ubifs_assert(written <= size);
491 return written;
492}
493
494static int remove_xattr(struct ubifs_info *c, struct inode *host,
495 struct inode *inode, const struct qstr *nm)
496{
497 int err;
498 struct ubifs_inode *host_ui = ubifs_inode(host);
499 struct ubifs_inode *ui = ubifs_inode(inode);
500 struct ubifs_budget_req req = { .dirtied_ino = 1, .mod_dent = 1,
501 .dirtied_ino_d = host_ui->data_len };
502
503 ubifs_assert(ui->data_len == inode->i_size);
504
505 err = ubifs_budget_space(c, &req);
506 if (err)
507 return err;
508
509 mutex_lock(&host_ui->ui_mutex);
510 host->i_ctime = ubifs_current_time(host);
511 host_ui->xattr_cnt -= 1;
512 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
513 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
514 host_ui->xattr_names -= nm->len;
515
516 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
517 if (err)
518 goto out_cancel;
519 mutex_unlock(&host_ui->ui_mutex);
520
521 ubifs_release_budget(c, &req);
522 return 0;
523
524out_cancel:
525 host_ui->xattr_cnt += 1;
526 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
527 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
528 mutex_unlock(&host_ui->ui_mutex);
529 ubifs_release_budget(c, &req);
530 make_bad_inode(inode);
531 return err;
532}
533
534int ubifs_removexattr(struct dentry *dentry, const char *name)
535{
536 struct inode *inode, *host = dentry->d_inode;
537 struct ubifs_info *c = host->i_sb->s_fs_info;
538 struct qstr nm = { .name = name, .len = strlen(name) };
539 struct ubifs_dent_node *xent;
540 union ubifs_key key;
541 int err;
542
543 dbg_gen("xattr '%s', ino %lu ('%.*s')", name,
544 host->i_ino, dentry->d_name.len, dentry->d_name.name);
545 ubifs_assert(mutex_is_locked(&host->i_mutex));
546
547 err = check_namespace(&nm);
548 if (err < 0)
549 return err;
550
551 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
552 if (!xent)
553 return -ENOMEM;
554
555 xent_key_init(c, &key, host->i_ino, &nm);
556 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
557 if (err) {
558 if (err == -ENOENT)
559 err = -ENODATA;
560 goto out_free;
561 }
562
563 inode = iget_xattr(c, le64_to_cpu(xent->inum));
564 if (IS_ERR(inode)) {
565 err = PTR_ERR(inode);
566 goto out_free;
567 }
568
569 ubifs_assert(inode->i_nlink == 1);
570 inode->i_nlink = 0;
571 err = remove_xattr(c, host, inode, &nm);
572 if (err)
573 inode->i_nlink = 1;
574
575 /* If @i_nlink is 0, 'iput()' will delete the inode */
576 iput(inode);
577
578out_free:
579 kfree(xent);
580 return err;
581}