staging:iio:light:tsl2563 remove old style event registration.
[zen-stable.git] / fs / ubifs / xattr.c
blob3299f469e7126a004d2b3a37c5c2661b3c6a127d
1 /*
2 * This file is part of UBIFS.
4 * Copyright (C) 2006-2008 Nokia Corporation.
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.
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.
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
19 * Authors: Artem Bityutskiy (Битюцкий Артём)
20 * Adrian Hunter
24 * This file implements UBIFS extended attributes support.
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.
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.
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.
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.
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).
55 * ACL support is not implemented.
58 #include "ubifs.h"
59 #include <linux/fs.h>
60 #include <linux/slab.h>
61 #include <linux/xattr.h>
62 #include <linux/posix_acl_xattr.h>
65 * Limit the number of extended attributes per inode so that the total size
66 * (@xattr_size) is guaranteeded to fit in an 'unsigned int'.
68 #define MAX_XATTRS_PER_INODE 65535
71 * Extended attribute type constants.
73 * USER_XATTR: user extended attribute ("user.*")
74 * TRUSTED_XATTR: trusted extended attribute ("trusted.*)
75 * SECURITY_XATTR: security extended attribute ("security.*")
77 enum {
78 USER_XATTR,
79 TRUSTED_XATTR,
80 SECURITY_XATTR,
83 static const struct inode_operations none_inode_operations;
84 static const struct file_operations none_file_operations;
86 /**
87 * create_xattr - create an extended attribute.
88 * @c: UBIFS file-system description object
89 * @host: host inode
90 * @nm: extended attribute name
91 * @value: extended attribute value
92 * @size: size of extended attribute value
94 * This is a helper function which creates an extended attribute of name @nm
95 * and value @value for inode @host. The host inode is also updated on flash
96 * because the ctime and extended attribute accounting data changes. This
97 * function returns zero in case of success and a negative error code in case
98 * of failure.
100 static int create_xattr(struct ubifs_info *c, struct inode *host,
101 const struct qstr *nm, const void *value, int size)
103 int err;
104 struct inode *inode;
105 struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
106 struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
107 .new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
108 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
110 if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE)
111 return -ENOSPC;
113 * Linux limits the maximum size of the extended attribute names list
114 * to %XATTR_LIST_MAX. This means we should not allow creating more
115 * extended attributes if the name list becomes larger. This limitation
116 * is artificial for UBIFS, though.
118 if (host_ui->xattr_names + host_ui->xattr_cnt +
119 nm->len + 1 > XATTR_LIST_MAX)
120 return -ENOSPC;
122 err = ubifs_budget_space(c, &req);
123 if (err)
124 return err;
126 inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
127 if (IS_ERR(inode)) {
128 err = PTR_ERR(inode);
129 goto out_budg;
132 /* Re-define all operations to be "nothing" */
133 inode->i_mapping->a_ops = &empty_aops;
134 inode->i_op = &none_inode_operations;
135 inode->i_fop = &none_file_operations;
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_free;
146 memcpy(ui->data, value, size);
147 inode->i_size = ui->ui_size = size;
148 ui->data_len = size;
150 mutex_lock(&host_ui->ui_mutex);
151 host->i_ctime = ubifs_current_time(host);
152 host_ui->xattr_cnt += 1;
153 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
154 host_ui->xattr_size += CALC_XATTR_BYTES(size);
155 host_ui->xattr_names += nm->len;
157 err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
158 if (err)
159 goto out_cancel;
160 mutex_unlock(&host_ui->ui_mutex);
162 ubifs_release_budget(c, &req);
163 insert_inode_hash(inode);
164 iput(inode);
165 return 0;
167 out_cancel:
168 host_ui->xattr_cnt -= 1;
169 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
170 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
171 mutex_unlock(&host_ui->ui_mutex);
172 out_free:
173 make_bad_inode(inode);
174 iput(inode);
175 out_budg:
176 ubifs_release_budget(c, &req);
177 return err;
181 * change_xattr - change an extended attribute.
182 * @c: UBIFS file-system description object
183 * @host: host inode
184 * @inode: extended attribute inode
185 * @value: extended attribute value
186 * @size: size of extended attribute value
188 * This helper function changes the value of extended attribute @inode with new
189 * data from @value. Returns zero in case of success and a negative error code
190 * in case of failure.
192 static int change_xattr(struct ubifs_info *c, struct inode *host,
193 struct inode *inode, const void *value, int size)
195 int err;
196 struct ubifs_inode *host_ui = ubifs_inode(host);
197 struct ubifs_inode *ui = ubifs_inode(inode);
198 struct ubifs_budget_req req = { .dirtied_ino = 2,
199 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
201 ubifs_assert(ui->data_len == inode->i_size);
202 err = ubifs_budget_space(c, &req);
203 if (err)
204 return err;
206 kfree(ui->data);
207 ui->data = kmalloc(size, GFP_NOFS);
208 if (!ui->data) {
209 err = -ENOMEM;
210 goto out_free;
212 memcpy(ui->data, value, size);
213 inode->i_size = ui->ui_size = size;
214 ui->data_len = size;
216 mutex_lock(&host_ui->ui_mutex);
217 host->i_ctime = ubifs_current_time(host);
218 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
219 host_ui->xattr_size += CALC_XATTR_BYTES(size);
222 * It is important to write the host inode after the xattr inode
223 * because if the host inode gets synchronized (via 'fsync()'), then
224 * the extended attribute inode gets synchronized, because it goes
225 * before the host inode in the write-buffer.
227 err = ubifs_jnl_change_xattr(c, inode, host);
228 if (err)
229 goto out_cancel;
230 mutex_unlock(&host_ui->ui_mutex);
232 ubifs_release_budget(c, &req);
233 return 0;
235 out_cancel:
236 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
237 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
238 mutex_unlock(&host_ui->ui_mutex);
239 make_bad_inode(inode);
240 out_free:
241 ubifs_release_budget(c, &req);
242 return err;
246 * check_namespace - check extended attribute name-space.
247 * @nm: extended attribute name
249 * This function makes sure the extended attribute name belongs to one of the
250 * supported extended attribute name-spaces. Returns name-space index in case
251 * of success and a negative error code in case of failure.
253 static int check_namespace(const struct qstr *nm)
255 int type;
257 if (nm->len > UBIFS_MAX_NLEN)
258 return -ENAMETOOLONG;
260 if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
261 XATTR_TRUSTED_PREFIX_LEN)) {
262 if (nm->name[sizeof(XATTR_TRUSTED_PREFIX) - 1] == '\0')
263 return -EINVAL;
264 type = TRUSTED_XATTR;
265 } else if (!strncmp(nm->name, XATTR_USER_PREFIX,
266 XATTR_USER_PREFIX_LEN)) {
267 if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
268 return -EINVAL;
269 type = USER_XATTR;
270 } else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
271 XATTR_SECURITY_PREFIX_LEN)) {
272 if (nm->name[sizeof(XATTR_SECURITY_PREFIX) - 1] == '\0')
273 return -EINVAL;
274 type = SECURITY_XATTR;
275 } else
276 return -EOPNOTSUPP;
278 return type;
281 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
283 struct inode *inode;
285 inode = ubifs_iget(c->vfs_sb, inum);
286 if (IS_ERR(inode)) {
287 ubifs_err("dead extended attribute entry, error %d",
288 (int)PTR_ERR(inode));
289 return inode;
291 if (ubifs_inode(inode)->xattr)
292 return inode;
293 ubifs_err("corrupt extended attribute entry");
294 iput(inode);
295 return ERR_PTR(-EINVAL);
298 int ubifs_setxattr(struct dentry *dentry, const char *name,
299 const void *value, size_t size, int flags)
301 struct inode *inode, *host = dentry->d_inode;
302 struct ubifs_info *c = host->i_sb->s_fs_info;
303 struct qstr nm = { .name = name, .len = strlen(name) };
304 struct ubifs_dent_node *xent;
305 union ubifs_key key;
306 int err, type;
308 dbg_gen("xattr '%s', host ino %lu ('%.*s'), size %zd", name,
309 host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
310 ubifs_assert(mutex_is_locked(&host->i_mutex));
312 if (size > UBIFS_MAX_INO_DATA)
313 return -ERANGE;
315 type = check_namespace(&nm);
316 if (type < 0)
317 return type;
319 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
320 if (!xent)
321 return -ENOMEM;
324 * The extended attribute entries are stored in LNC, so multiple
325 * look-ups do not involve reading the flash.
327 xent_key_init(c, &key, host->i_ino, &nm);
328 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
329 if (err) {
330 if (err != -ENOENT)
331 goto out_free;
333 if (flags & XATTR_REPLACE)
334 /* We are asked not to create the xattr */
335 err = -ENODATA;
336 else
337 err = create_xattr(c, host, &nm, value, size);
338 goto out_free;
341 if (flags & XATTR_CREATE) {
342 /* We are asked not to replace the xattr */
343 err = -EEXIST;
344 goto out_free;
347 inode = iget_xattr(c, le64_to_cpu(xent->inum));
348 if (IS_ERR(inode)) {
349 err = PTR_ERR(inode);
350 goto out_free;
353 err = change_xattr(c, host, inode, value, size);
354 iput(inode);
356 out_free:
357 kfree(xent);
358 return err;
361 ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
362 size_t size)
364 struct inode *inode, *host = dentry->d_inode;
365 struct ubifs_info *c = host->i_sb->s_fs_info;
366 struct qstr nm = { .name = name, .len = strlen(name) };
367 struct ubifs_inode *ui;
368 struct ubifs_dent_node *xent;
369 union ubifs_key key;
370 int err;
372 dbg_gen("xattr '%s', ino %lu ('%.*s'), buf size %zd", name,
373 host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
375 err = check_namespace(&nm);
376 if (err < 0)
377 return err;
379 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
380 if (!xent)
381 return -ENOMEM;
383 xent_key_init(c, &key, host->i_ino, &nm);
384 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
385 if (err) {
386 if (err == -ENOENT)
387 err = -ENODATA;
388 goto out_unlock;
391 inode = iget_xattr(c, le64_to_cpu(xent->inum));
392 if (IS_ERR(inode)) {
393 err = PTR_ERR(inode);
394 goto out_unlock;
397 ui = ubifs_inode(inode);
398 ubifs_assert(inode->i_size == ui->data_len);
399 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
401 if (buf) {
402 /* If @buf is %NULL we are supposed to return the length */
403 if (ui->data_len > size) {
404 dbg_err("buffer size %zd, xattr len %d",
405 size, ui->data_len);
406 err = -ERANGE;
407 goto out_iput;
410 memcpy(buf, ui->data, ui->data_len);
412 err = ui->data_len;
414 out_iput:
415 iput(inode);
416 out_unlock:
417 kfree(xent);
418 return err;
421 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
423 union ubifs_key key;
424 struct inode *host = dentry->d_inode;
425 struct ubifs_info *c = host->i_sb->s_fs_info;
426 struct ubifs_inode *host_ui = ubifs_inode(host);
427 struct ubifs_dent_node *xent, *pxent = NULL;
428 int err, len, written = 0;
429 struct qstr nm = { .name = NULL };
431 dbg_gen("ino %lu ('%.*s'), buffer size %zd", host->i_ino,
432 dentry->d_name.len, dentry->d_name.name, size);
434 len = host_ui->xattr_names + host_ui->xattr_cnt;
435 if (!buffer)
437 * We should return the minimum buffer size which will fit a
438 * null-terminated list of all the extended attribute names.
440 return len;
442 if (len > size)
443 return -ERANGE;
445 lowest_xent_key(c, &key, host->i_ino);
446 while (1) {
447 int type;
449 xent = ubifs_tnc_next_ent(c, &key, &nm);
450 if (IS_ERR(xent)) {
451 err = PTR_ERR(xent);
452 break;
455 nm.name = xent->name;
456 nm.len = le16_to_cpu(xent->nlen);
458 type = check_namespace(&nm);
459 if (unlikely(type < 0)) {
460 err = type;
461 break;
464 /* Show trusted namespace only for "power" users */
465 if (type != TRUSTED_XATTR || capable(CAP_SYS_ADMIN)) {
466 memcpy(buffer + written, nm.name, nm.len + 1);
467 written += nm.len + 1;
470 kfree(pxent);
471 pxent = xent;
472 key_read(c, &xent->key, &key);
475 kfree(pxent);
476 if (err != -ENOENT) {
477 ubifs_err("cannot find next direntry, error %d", err);
478 return err;
481 ubifs_assert(written <= size);
482 return written;
485 static int remove_xattr(struct ubifs_info *c, struct inode *host,
486 struct inode *inode, const struct qstr *nm)
488 int err;
489 struct ubifs_inode *host_ui = ubifs_inode(host);
490 struct ubifs_inode *ui = ubifs_inode(inode);
491 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
492 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
494 ubifs_assert(ui->data_len == inode->i_size);
496 err = ubifs_budget_space(c, &req);
497 if (err)
498 return err;
500 mutex_lock(&host_ui->ui_mutex);
501 host->i_ctime = ubifs_current_time(host);
502 host_ui->xattr_cnt -= 1;
503 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
504 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
505 host_ui->xattr_names -= nm->len;
507 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
508 if (err)
509 goto out_cancel;
510 mutex_unlock(&host_ui->ui_mutex);
512 ubifs_release_budget(c, &req);
513 return 0;
515 out_cancel:
516 host_ui->xattr_cnt += 1;
517 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
518 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
519 mutex_unlock(&host_ui->ui_mutex);
520 ubifs_release_budget(c, &req);
521 make_bad_inode(inode);
522 return err;
525 int ubifs_removexattr(struct dentry *dentry, const char *name)
527 struct inode *inode, *host = dentry->d_inode;
528 struct ubifs_info *c = host->i_sb->s_fs_info;
529 struct qstr nm = { .name = name, .len = strlen(name) };
530 struct ubifs_dent_node *xent;
531 union ubifs_key key;
532 int err;
534 dbg_gen("xattr '%s', ino %lu ('%.*s')", name,
535 host->i_ino, dentry->d_name.len, dentry->d_name.name);
536 ubifs_assert(mutex_is_locked(&host->i_mutex));
538 err = check_namespace(&nm);
539 if (err < 0)
540 return err;
542 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
543 if (!xent)
544 return -ENOMEM;
546 xent_key_init(c, &key, host->i_ino, &nm);
547 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
548 if (err) {
549 if (err == -ENOENT)
550 err = -ENODATA;
551 goto out_free;
554 inode = iget_xattr(c, le64_to_cpu(xent->inum));
555 if (IS_ERR(inode)) {
556 err = PTR_ERR(inode);
557 goto out_free;
560 ubifs_assert(inode->i_nlink == 1);
561 inode->i_nlink = 0;
562 err = remove_xattr(c, host, inode, &nm);
563 if (err)
564 inode->i_nlink = 1;
566 /* If @i_nlink is 0, 'iput()' will delete the inode */
567 iput(inode);
569 out_free:
570 kfree(xent);
571 return err;