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);
203 struct ubifs_budget_req req = { .dirtied_ino = 2,
204 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
206 ubifs_assert(ui->data_len == inode->i_size);
207 err = ubifs_budget_space(c, &req);
212 ui->data = kmemdup(value, size, GFP_NOFS);
217 inode->i_size = ui->ui_size = size;
220 mutex_lock(&host_ui->ui_mutex);
221 host->i_ctime = ubifs_current_time(host);
222 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
223 host_ui->xattr_size += CALC_XATTR_BYTES(size);
226 * It is important to write the host inode after the xattr inode
227 * because if the host inode gets synchronized (via 'fsync()'), then
228 * the extended attribute inode gets synchronized, because it goes
229 * before the host inode in the write-buffer.
231 err = ubifs_jnl_change_xattr(c, inode, host);
234 mutex_unlock(&host_ui->ui_mutex);
236 ubifs_release_budget(c, &req);
240 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
241 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
242 mutex_unlock(&host_ui->ui_mutex);
243 make_bad_inode(inode);
245 ubifs_release_budget(c, &req);
250 * check_namespace - check extended attribute name-space.
251 * @nm: extended attribute name
253 * This function makes sure the extended attribute name belongs to one of the
254 * supported extended attribute name-spaces. Returns name-space index in case
255 * of success and a negative error code in case of failure.
257 static int check_namespace(const struct qstr *nm)
261 if (nm->len > UBIFS_MAX_NLEN)
262 return -ENAMETOOLONG;
264 if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
265 XATTR_TRUSTED_PREFIX_LEN)) {
266 if (nm->name[sizeof(XATTR_TRUSTED_PREFIX) - 1] == '\0')
268 type = TRUSTED_XATTR;
269 } else if (!strncmp(nm->name, XATTR_USER_PREFIX,
270 XATTR_USER_PREFIX_LEN)) {
271 if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
274 } else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
275 XATTR_SECURITY_PREFIX_LEN)) {
276 if (nm->name[sizeof(XATTR_SECURITY_PREFIX) - 1] == '\0')
278 type = SECURITY_XATTR;
285 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
289 inode = ubifs_iget(c->vfs_sb, inum);
291 ubifs_err(c, "dead extended attribute entry, error %d",
292 (int)PTR_ERR(inode));
295 if (ubifs_inode(inode)->xattr)
297 ubifs_err(c, "corrupt extended attribute entry");
299 return ERR_PTR(-EINVAL);
302 static int setxattr(struct inode *host, const char *name, const void *value,
303 size_t size, int flags)
306 struct ubifs_info *c = host->i_sb->s_fs_info;
307 struct qstr nm = QSTR_INIT(name, strlen(name));
308 struct ubifs_dent_node *xent;
312 ubifs_assert(mutex_is_locked(&host->i_mutex));
314 if (size > UBIFS_MAX_INO_DATA)
317 type = check_namespace(&nm);
321 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
326 * The extended attribute entries are stored in LNC, so multiple
327 * look-ups do not involve reading the flash.
329 xent_key_init(c, &key, host->i_ino, &nm);
330 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
335 if (flags & XATTR_REPLACE)
336 /* We are asked not to create the xattr */
339 err = create_xattr(c, host, &nm, value, size);
343 if (flags & XATTR_CREATE) {
344 /* We are asked not to replace the xattr */
349 inode = iget_xattr(c, le64_to_cpu(xent->inum));
351 err = PTR_ERR(inode);
355 err = change_xattr(c, host, inode, value, size);
363 int ubifs_setxattr(struct dentry *dentry, const char *name,
364 const void *value, size_t size, int flags)
366 dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
367 name, d_inode(dentry)->i_ino, dentry, size);
369 return setxattr(d_inode(dentry), name, value, size, flags);
372 ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
375 struct inode *inode, *host = d_inode(dentry);
376 struct ubifs_info *c = host->i_sb->s_fs_info;
377 struct qstr nm = QSTR_INIT(name, strlen(name));
378 struct ubifs_inode *ui;
379 struct ubifs_dent_node *xent;
383 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
384 host->i_ino, dentry, size);
386 err = check_namespace(&nm);
390 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
394 xent_key_init(c, &key, host->i_ino, &nm);
395 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
402 inode = iget_xattr(c, le64_to_cpu(xent->inum));
404 err = PTR_ERR(inode);
408 ui = ubifs_inode(inode);
409 ubifs_assert(inode->i_size == ui->data_len);
410 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
413 /* If @buf is %NULL we are supposed to return the length */
414 if (ui->data_len > size) {
415 ubifs_err(c, "buffer size %zd, xattr len %d",
421 memcpy(buf, ui->data, ui->data_len);
432 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
435 struct inode *host = d_inode(dentry);
436 struct ubifs_info *c = host->i_sb->s_fs_info;
437 struct ubifs_inode *host_ui = ubifs_inode(host);
438 struct ubifs_dent_node *xent, *pxent = NULL;
439 int err, len, written = 0;
440 struct qstr nm = { .name = NULL };
442 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
445 len = host_ui->xattr_names + host_ui->xattr_cnt;
448 * We should return the minimum buffer size which will fit a
449 * null-terminated list of all the extended attribute names.
456 lowest_xent_key(c, &key, host->i_ino);
460 xent = ubifs_tnc_next_ent(c, &key, &nm);
466 nm.name = xent->name;
467 nm.len = le16_to_cpu(xent->nlen);
469 type = check_namespace(&nm);
470 if (unlikely(type < 0)) {
475 /* Show trusted namespace only for "power" users */
476 if (type != TRUSTED_XATTR || capable(CAP_SYS_ADMIN)) {
477 memcpy(buffer + written, nm.name, nm.len + 1);
478 written += nm.len + 1;
483 key_read(c, &xent->key, &key);
487 if (err != -ENOENT) {
488 ubifs_err(c, "cannot find next direntry, error %d", err);
492 ubifs_assert(written <= size);
496 static int remove_xattr(struct ubifs_info *c, struct inode *host,
497 struct inode *inode, const struct qstr *nm)
500 struct ubifs_inode *host_ui = ubifs_inode(host);
501 struct ubifs_inode *ui = ubifs_inode(inode);
502 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
503 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
505 ubifs_assert(ui->data_len == inode->i_size);
507 err = ubifs_budget_space(c, &req);
511 mutex_lock(&host_ui->ui_mutex);
512 host->i_ctime = ubifs_current_time(host);
513 host_ui->xattr_cnt -= 1;
514 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
515 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
516 host_ui->xattr_names -= nm->len;
518 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
521 mutex_unlock(&host_ui->ui_mutex);
523 ubifs_release_budget(c, &req);
527 host_ui->xattr_cnt += 1;
528 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
529 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
530 mutex_unlock(&host_ui->ui_mutex);
531 ubifs_release_budget(c, &req);
532 make_bad_inode(inode);
536 int ubifs_removexattr(struct dentry *dentry, const char *name)
538 struct inode *inode, *host = d_inode(dentry);
539 struct ubifs_info *c = host->i_sb->s_fs_info;
540 struct qstr nm = QSTR_INIT(name, strlen(name));
541 struct ubifs_dent_node *xent;
545 dbg_gen("xattr '%s', ino %lu ('%pd')", name,
546 host->i_ino, dentry);
547 ubifs_assert(mutex_is_locked(&host->i_mutex));
549 err = check_namespace(&nm);
553 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
557 xent_key_init(c, &key, host->i_ino, &nm);
558 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
565 inode = iget_xattr(c, le64_to_cpu(xent->inum));
567 err = PTR_ERR(inode);
571 ubifs_assert(inode->i_nlink == 1);
573 err = remove_xattr(c, host, inode, &nm);
577 /* If @i_nlink is 0, 'iput()' will delete the inode */
585 static size_t security_listxattr(struct dentry *d, char *list, size_t list_size,
586 const char *name, size_t name_len, int flags)
588 const int prefix_len = XATTR_SECURITY_PREFIX_LEN;
589 const size_t total_len = prefix_len + name_len + 1;
591 if (list && total_len <= list_size) {
592 memcpy(list, XATTR_SECURITY_PREFIX, prefix_len);
593 memcpy(list + prefix_len, name, name_len);
594 list[prefix_len + name_len] = '\0';
600 static int security_getxattr(struct dentry *d, const char *name, void *buffer,
601 size_t size, int flags)
603 return ubifs_getxattr(d, name, buffer, size);
606 static int security_setxattr(struct dentry *d, const char *name,
607 const void *value, size_t size, int flags,
610 return ubifs_setxattr(d, name, value, size, flags);
613 static const struct xattr_handler ubifs_xattr_security_handler = {
614 .prefix = XATTR_SECURITY_PREFIX,
615 .list = security_listxattr,
616 .get = security_getxattr,
617 .set = security_setxattr,
620 const struct xattr_handler *ubifs_xattr_handlers[] = {
621 &ubifs_xattr_security_handler,
625 static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
628 const struct xattr *xattr;
632 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
633 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
634 strlen(xattr->name) + 1, GFP_NOFS);
639 strcpy(name, XATTR_SECURITY_PREFIX);
640 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
641 err = setxattr(inode, name, xattr->value, xattr->value_len, 0);
650 int ubifs_init_security(struct inode *dentry, struct inode *inode,
651 const struct qstr *qstr)
655 err = security_inode_init_security(inode, dentry, qstr,
658 struct ubifs_info *c = dentry->i_sb->s_fs_info;
659 ubifs_err(c, "cannot initialize security for inode %lu, error %d",