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
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)
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
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
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
55 * ACL support is not implemented.
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.*")
83 static const struct inode_operations empty_iops;
84 static const struct file_operations empty_fops;
87 * create_xattr - create an extended attribute.
88 * @c: UBIFS file-system description object
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
100 static int create_xattr(struct ubifs_info *c, struct inode *host,
101 const struct qstr *nm, const void *value, int size)
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 ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
112 host->i_ino, host_ui->xattr_cnt);
116 * Linux limits the maximum size of the extended attribute names list
117 * to %XATTR_LIST_MAX. This means we should not allow creating more
118 * extended attributes if the name list becomes larger. This limitation
119 * is artificial for UBIFS, though.
121 names_len = host_ui->xattr_names + host_ui->xattr_cnt + nm->len + 1;
122 if (names_len > XATTR_LIST_MAX) {
123 ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
124 host->i_ino, names_len, XATTR_LIST_MAX);
128 err = ubifs_budget_space(c, &req);
132 inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
134 err = PTR_ERR(inode);
138 /* Re-define all operations to be "nothing" */
139 inode->i_mapping->a_ops = &empty_aops;
140 inode->i_op = &empty_iops;
141 inode->i_fop = &empty_fops;
143 inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME | S_NOQUOTA;
144 ui = ubifs_inode(inode);
146 ui->flags |= UBIFS_XATTR_FL;
147 ui->data = kmemdup(value, size, GFP_NOFS);
152 inode->i_size = ui->ui_size = size;
155 mutex_lock(&host_ui->ui_mutex);
156 host->i_ctime = ubifs_current_time(host);
157 host_ui->xattr_cnt += 1;
158 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
159 host_ui->xattr_size += CALC_XATTR_BYTES(size);
160 host_ui->xattr_names += nm->len;
162 err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
165 mutex_unlock(&host_ui->ui_mutex);
167 ubifs_release_budget(c, &req);
168 insert_inode_hash(inode);
173 host_ui->xattr_cnt -= 1;
174 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
175 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
176 mutex_unlock(&host_ui->ui_mutex);
178 make_bad_inode(inode);
181 ubifs_release_budget(c, &req);
186 * change_xattr - change an extended attribute.
187 * @c: UBIFS file-system description object
189 * @inode: extended attribute inode
190 * @value: extended attribute value
191 * @size: size of extended attribute value
193 * This helper function changes the value of extended attribute @inode with new
194 * data from @value. Returns zero in case of success and a negative error code
195 * in case of failure.
197 static int change_xattr(struct ubifs_info *c, struct inode *host,
198 struct inode *inode, const void *value, int size)
201 struct ubifs_inode *host_ui = ubifs_inode(host);
202 struct ubifs_inode *ui = ubifs_inode(inode);
204 struct ubifs_budget_req req = { .dirtied_ino = 2,
205 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
207 ubifs_assert(ui->data_len == inode->i_size);
208 err = ubifs_budget_space(c, &req);
212 buf = kmemdup(value, size, GFP_NOFS);
217 mutex_lock(&ui->ui_mutex);
220 inode->i_size = ui->ui_size = size;
222 mutex_unlock(&ui->ui_mutex);
224 mutex_lock(&host_ui->ui_mutex);
225 host->i_ctime = ubifs_current_time(host);
226 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
227 host_ui->xattr_size += CALC_XATTR_BYTES(size);
230 * It is important to write the host inode after the xattr inode
231 * because if the host inode gets synchronized (via 'fsync()'), then
232 * the extended attribute inode gets synchronized, because it goes
233 * before the host inode in the write-buffer.
235 err = ubifs_jnl_change_xattr(c, inode, host);
238 mutex_unlock(&host_ui->ui_mutex);
240 ubifs_release_budget(c, &req);
244 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
245 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
246 mutex_unlock(&host_ui->ui_mutex);
247 make_bad_inode(inode);
249 ubifs_release_budget(c, &req);
254 * check_namespace - check extended attribute name-space.
255 * @nm: extended attribute name
257 * This function makes sure the extended attribute name belongs to one of the
258 * supported extended attribute name-spaces. Returns name-space index in case
259 * of success and a negative error code in case of failure.
261 static int check_namespace(const struct qstr *nm)
265 if (nm->len > UBIFS_MAX_NLEN)
266 return -ENAMETOOLONG;
268 if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
269 XATTR_TRUSTED_PREFIX_LEN)) {
270 if (nm->name[sizeof(XATTR_TRUSTED_PREFIX) - 1] == '\0')
272 type = TRUSTED_XATTR;
273 } else if (!strncmp(nm->name, XATTR_USER_PREFIX,
274 XATTR_USER_PREFIX_LEN)) {
275 if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
278 } else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
279 XATTR_SECURITY_PREFIX_LEN)) {
280 if (nm->name[sizeof(XATTR_SECURITY_PREFIX) - 1] == '\0')
282 type = SECURITY_XATTR;
289 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
293 inode = ubifs_iget(c->vfs_sb, inum);
295 ubifs_err(c, "dead extended attribute entry, error %d",
296 (int)PTR_ERR(inode));
299 if (ubifs_inode(inode)->xattr)
301 ubifs_err(c, "corrupt extended attribute entry");
303 return ERR_PTR(-EINVAL);
306 static int setxattr(struct inode *host, const char *name, const void *value,
307 size_t size, int flags)
310 struct ubifs_info *c = host->i_sb->s_fs_info;
311 struct qstr nm = QSTR_INIT(name, strlen(name));
312 struct ubifs_dent_node *xent;
316 ubifs_assert(mutex_is_locked(&host->i_mutex));
318 if (size > UBIFS_MAX_INO_DATA)
321 type = check_namespace(&nm);
325 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
330 * The extended attribute entries are stored in LNC, so multiple
331 * look-ups do not involve reading the flash.
333 xent_key_init(c, &key, host->i_ino, &nm);
334 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
339 if (flags & XATTR_REPLACE)
340 /* We are asked not to create the xattr */
343 err = create_xattr(c, host, &nm, value, size);
347 if (flags & XATTR_CREATE) {
348 /* We are asked not to replace the xattr */
353 inode = iget_xattr(c, le64_to_cpu(xent->inum));
355 err = PTR_ERR(inode);
359 err = change_xattr(c, host, inode, value, size);
367 int ubifs_setxattr(struct dentry *dentry, const char *name,
368 const void *value, size_t size, int flags)
370 dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
371 name, d_inode(dentry)->i_ino, dentry, size);
373 return setxattr(d_inode(dentry), name, value, size, flags);
376 ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
379 struct inode *inode, *host = d_inode(dentry);
380 struct ubifs_info *c = host->i_sb->s_fs_info;
381 struct qstr nm = QSTR_INIT(name, strlen(name));
382 struct ubifs_inode *ui;
383 struct ubifs_dent_node *xent;
387 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
388 host->i_ino, dentry, size);
390 err = check_namespace(&nm);
394 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
398 xent_key_init(c, &key, host->i_ino, &nm);
399 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
406 inode = iget_xattr(c, le64_to_cpu(xent->inum));
408 err = PTR_ERR(inode);
412 ui = ubifs_inode(inode);
413 ubifs_assert(inode->i_size == ui->data_len);
414 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
416 mutex_lock(&ui->ui_mutex);
418 /* If @buf is %NULL we are supposed to return the length */
419 if (ui->data_len > size) {
420 ubifs_err(c, "buffer size %zd, xattr len %d",
426 memcpy(buf, ui->data, ui->data_len);
431 mutex_unlock(&ui->ui_mutex);
438 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
441 struct inode *host = d_inode(dentry);
442 struct ubifs_info *c = host->i_sb->s_fs_info;
443 struct ubifs_inode *host_ui = ubifs_inode(host);
444 struct ubifs_dent_node *xent, *pxent = NULL;
445 int err, len, written = 0;
446 struct qstr nm = { .name = NULL };
448 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
451 len = host_ui->xattr_names + host_ui->xattr_cnt;
454 * We should return the minimum buffer size which will fit a
455 * null-terminated list of all the extended attribute names.
462 lowest_xent_key(c, &key, host->i_ino);
466 xent = ubifs_tnc_next_ent(c, &key, &nm);
472 nm.name = xent->name;
473 nm.len = le16_to_cpu(xent->nlen);
475 type = check_namespace(&nm);
476 if (unlikely(type < 0)) {
481 /* Show trusted namespace only for "power" users */
482 if (type != TRUSTED_XATTR || capable(CAP_SYS_ADMIN)) {
483 memcpy(buffer + written, nm.name, nm.len + 1);
484 written += nm.len + 1;
489 key_read(c, &xent->key, &key);
493 if (err != -ENOENT) {
494 ubifs_err(c, "cannot find next direntry, error %d", err);
498 ubifs_assert(written <= size);
502 static int remove_xattr(struct ubifs_info *c, struct inode *host,
503 struct inode *inode, const struct qstr *nm)
506 struct ubifs_inode *host_ui = ubifs_inode(host);
507 struct ubifs_inode *ui = ubifs_inode(inode);
508 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
509 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
511 ubifs_assert(ui->data_len == inode->i_size);
513 err = ubifs_budget_space(c, &req);
517 mutex_lock(&host_ui->ui_mutex);
518 host->i_ctime = ubifs_current_time(host);
519 host_ui->xattr_cnt -= 1;
520 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
521 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
522 host_ui->xattr_names -= nm->len;
524 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
527 mutex_unlock(&host_ui->ui_mutex);
529 ubifs_release_budget(c, &req);
533 host_ui->xattr_cnt += 1;
534 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
535 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
536 mutex_unlock(&host_ui->ui_mutex);
537 ubifs_release_budget(c, &req);
538 make_bad_inode(inode);
542 int ubifs_removexattr(struct dentry *dentry, const char *name)
544 struct inode *inode, *host = d_inode(dentry);
545 struct ubifs_info *c = host->i_sb->s_fs_info;
546 struct qstr nm = QSTR_INIT(name, strlen(name));
547 struct ubifs_dent_node *xent;
551 dbg_gen("xattr '%s', ino %lu ('%pd')", name,
552 host->i_ino, dentry);
553 ubifs_assert(mutex_is_locked(&host->i_mutex));
555 err = check_namespace(&nm);
559 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
563 xent_key_init(c, &key, host->i_ino, &nm);
564 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
571 inode = iget_xattr(c, le64_to_cpu(xent->inum));
573 err = PTR_ERR(inode);
577 ubifs_assert(inode->i_nlink == 1);
579 err = remove_xattr(c, host, inode, &nm);
583 /* If @i_nlink is 0, 'iput()' will delete the inode */
591 static size_t security_listxattr(struct dentry *d, char *list, size_t list_size,
592 const char *name, size_t name_len, int flags)
594 const int prefix_len = XATTR_SECURITY_PREFIX_LEN;
595 const size_t total_len = prefix_len + name_len + 1;
597 if (list && total_len <= list_size) {
598 memcpy(list, XATTR_SECURITY_PREFIX, prefix_len);
599 memcpy(list + prefix_len, name, name_len);
600 list[prefix_len + name_len] = '\0';
606 static int security_getxattr(struct dentry *d, const char *name, void *buffer,
607 size_t size, int flags)
609 return ubifs_getxattr(d, name, buffer, size);
612 static int security_setxattr(struct dentry *d, const char *name,
613 const void *value, size_t size, int flags,
616 return ubifs_setxattr(d, name, value, size, flags);
619 static const struct xattr_handler ubifs_xattr_security_handler = {
620 .prefix = XATTR_SECURITY_PREFIX,
621 .list = security_listxattr,
622 .get = security_getxattr,
623 .set = security_setxattr,
626 const struct xattr_handler *ubifs_xattr_handlers[] = {
627 &ubifs_xattr_security_handler,
631 static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
634 const struct xattr *xattr;
638 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
639 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
640 strlen(xattr->name) + 1, GFP_NOFS);
645 strcpy(name, XATTR_SECURITY_PREFIX);
646 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
647 err = setxattr(inode, name, xattr->value, xattr->value_len, 0);
656 int ubifs_init_security(struct inode *dentry, struct inode *inode,
657 const struct qstr *qstr)
661 err = security_inode_init_security(inode, dentry, qstr,
664 struct ubifs_info *c = dentry->i_sb->s_fs_info;
665 ubifs_err(c, "cannot initialize security for inode %lu, error %d",