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>
64 * Limit the number of extended attributes per inode so that the total size
65 * (@xattr_size) is guaranteeded to fit in an 'unsigned int'.
67 #define MAX_XATTRS_PER_INODE 65535
70 * Extended attribute type constants.
72 * USER_XATTR: user extended attribute ("user.*")
73 * TRUSTED_XATTR: trusted extended attribute ("trusted.*)
74 * SECURITY_XATTR: security extended attribute ("security.*")
82 static const struct inode_operations empty_iops;
83 static const struct file_operations empty_fops;
86 * create_xattr - create an extended attribute.
87 * @c: UBIFS file-system description object
89 * @nm: extended attribute name
90 * @value: extended attribute value
91 * @size: size of extended attribute value
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
99 static int create_xattr(struct ubifs_info *c, struct inode *host,
100 const struct qstr *nm, const void *value, int size)
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 = ALIGN(size, 8), .dirtied_ino = 1,
107 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
109 if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE) {
110 ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
111 host->i_ino, host_ui->xattr_cnt);
115 * Linux limits the maximum size of the extended attribute names list
116 * to %XATTR_LIST_MAX. This means we should not allow creating more
117 * extended attributes if the name list becomes larger. This limitation
118 * is artificial for UBIFS, though.
120 names_len = host_ui->xattr_names + host_ui->xattr_cnt + nm->len + 1;
121 if (names_len > XATTR_LIST_MAX) {
122 ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
123 host->i_ino, names_len, XATTR_LIST_MAX);
127 err = ubifs_budget_space(c, &req);
131 inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
133 err = PTR_ERR(inode);
137 /* Re-define all operations to be "nothing" */
138 inode->i_mapping->a_ops = &empty_aops;
139 inode->i_op = &empty_iops;
140 inode->i_fop = &empty_fops;
142 inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME | S_NOQUOTA;
143 ui = ubifs_inode(inode);
145 ui->flags |= UBIFS_XATTR_FL;
146 ui->data = kmemdup(value, size, GFP_NOFS);
151 inode->i_size = ui->ui_size = size;
154 mutex_lock(&host_ui->ui_mutex);
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;
161 err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
164 mutex_unlock(&host_ui->ui_mutex);
166 ubifs_release_budget(c, &req);
167 insert_inode_hash(inode);
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);
175 host_ui->xattr_names -= nm->len;
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);
205 struct ubifs_budget_req req = { .dirtied_ino = 2,
206 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
208 ubifs_assert(ui->data_len == inode->i_size);
209 err = ubifs_budget_space(c, &req);
213 buf = kmemdup(value, size, GFP_NOFS);
218 mutex_lock(&ui->ui_mutex);
221 inode->i_size = ui->ui_size = size;
222 old_size = ui->data_len;
224 mutex_unlock(&ui->ui_mutex);
226 mutex_lock(&host_ui->ui_mutex);
227 host->i_ctime = ubifs_current_time(host);
228 host_ui->xattr_size -= CALC_XATTR_BYTES(old_size);
229 host_ui->xattr_size += CALC_XATTR_BYTES(size);
232 * It is important to write the host inode after the xattr inode
233 * because if the host inode gets synchronized (via 'fsync()'), then
234 * the extended attribute inode gets synchronized, because it goes
235 * before the host inode in the write-buffer.
237 err = ubifs_jnl_change_xattr(c, inode, host);
240 mutex_unlock(&host_ui->ui_mutex);
242 ubifs_release_budget(c, &req);
246 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
247 host_ui->xattr_size += CALC_XATTR_BYTES(old_size);
248 mutex_unlock(&host_ui->ui_mutex);
249 make_bad_inode(inode);
251 ubifs_release_budget(c, &req);
255 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
259 inode = ubifs_iget(c->vfs_sb, inum);
261 ubifs_err(c, "dead extended attribute entry, error %d",
262 (int)PTR_ERR(inode));
265 if (ubifs_inode(inode)->xattr)
267 ubifs_err(c, "corrupt extended attribute entry");
269 return ERR_PTR(-EINVAL);
272 static int __ubifs_setxattr(struct inode *host, const char *name,
273 const void *value, size_t size, int flags,
277 struct ubifs_info *c = host->i_sb->s_fs_info;
278 struct qstr nm = QSTR_INIT(name, strlen(name));
279 struct ubifs_dent_node *xent;
284 ubifs_assert(inode_is_locked(host));
286 if (size > UBIFS_MAX_INO_DATA)
289 if (nm.len > UBIFS_MAX_NLEN)
290 return -ENAMETOOLONG;
292 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
297 * The extended attribute entries are stored in LNC, so multiple
298 * look-ups do not involve reading the flash.
300 xent_key_init(c, &key, host->i_ino, &nm);
301 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
306 if (flags & XATTR_REPLACE)
307 /* We are asked not to create the xattr */
310 err = create_xattr(c, host, &nm, value, size);
314 if (flags & XATTR_CREATE) {
315 /* We are asked not to replace the xattr */
320 inode = iget_xattr(c, le64_to_cpu(xent->inum));
322 err = PTR_ERR(inode);
326 err = change_xattr(c, host, inode, value, size);
334 static ssize_t __ubifs_getxattr(struct inode *host, const char *name,
335 void *buf, size_t size)
338 struct ubifs_info *c = host->i_sb->s_fs_info;
339 struct qstr nm = QSTR_INIT(name, strlen(name));
340 struct ubifs_inode *ui;
341 struct ubifs_dent_node *xent;
345 if (nm.len > UBIFS_MAX_NLEN)
346 return -ENAMETOOLONG;
348 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
352 xent_key_init(c, &key, host->i_ino, &nm);
353 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
360 inode = iget_xattr(c, le64_to_cpu(xent->inum));
362 err = PTR_ERR(inode);
366 ui = ubifs_inode(inode);
367 ubifs_assert(inode->i_size == ui->data_len);
368 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
370 mutex_lock(&ui->ui_mutex);
372 /* If @buf is %NULL we are supposed to return the length */
373 if (ui->data_len > size) {
374 ubifs_err(c, "buffer size %zd, xattr len %d",
380 memcpy(buf, ui->data, ui->data_len);
385 mutex_unlock(&ui->ui_mutex);
392 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
395 struct inode *host = d_inode(dentry);
396 struct ubifs_info *c = host->i_sb->s_fs_info;
397 struct ubifs_inode *host_ui = ubifs_inode(host);
398 struct ubifs_dent_node *xent, *pxent = NULL;
399 int err, len, written = 0;
400 struct qstr nm = { .name = NULL };
402 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
405 len = host_ui->xattr_names + host_ui->xattr_cnt;
408 * We should return the minimum buffer size which will fit a
409 * null-terminated list of all the extended attribute names.
416 lowest_xent_key(c, &key, host->i_ino);
418 xent = ubifs_tnc_next_ent(c, &key, &nm);
424 nm.name = xent->name;
425 nm.len = le16_to_cpu(xent->nlen);
427 /* Show trusted namespace only for "power" users */
428 if (strncmp(xent->name, XATTR_TRUSTED_PREFIX,
429 XATTR_TRUSTED_PREFIX_LEN) ||
430 capable(CAP_SYS_ADMIN)) {
431 memcpy(buffer + written, nm.name, nm.len + 1);
432 written += nm.len + 1;
437 key_read(c, &xent->key, &key);
441 if (err != -ENOENT) {
442 ubifs_err(c, "cannot find next direntry, error %d", err);
446 ubifs_assert(written <= size);
450 static int remove_xattr(struct ubifs_info *c, struct inode *host,
451 struct inode *inode, const struct qstr *nm)
454 struct ubifs_inode *host_ui = ubifs_inode(host);
455 struct ubifs_inode *ui = ubifs_inode(inode);
456 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
457 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
459 ubifs_assert(ui->data_len == inode->i_size);
461 err = ubifs_budget_space(c, &req);
465 mutex_lock(&host_ui->ui_mutex);
466 host->i_ctime = ubifs_current_time(host);
467 host_ui->xattr_cnt -= 1;
468 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
469 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
470 host_ui->xattr_names -= nm->len;
472 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
475 mutex_unlock(&host_ui->ui_mutex);
477 ubifs_release_budget(c, &req);
481 host_ui->xattr_cnt += 1;
482 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
483 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
484 host_ui->xattr_names += nm->len;
485 mutex_unlock(&host_ui->ui_mutex);
486 ubifs_release_budget(c, &req);
487 make_bad_inode(inode);
491 static int __ubifs_removexattr(struct inode *host, const char *name)
494 struct ubifs_info *c = host->i_sb->s_fs_info;
495 struct qstr nm = QSTR_INIT(name, strlen(name));
496 struct ubifs_dent_node *xent;
500 ubifs_assert(inode_is_locked(host));
502 if (nm.len > UBIFS_MAX_NLEN)
503 return -ENAMETOOLONG;
505 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
509 xent_key_init(c, &key, host->i_ino, &nm);
510 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
517 inode = iget_xattr(c, le64_to_cpu(xent->inum));
519 err = PTR_ERR(inode);
523 ubifs_assert(inode->i_nlink == 1);
525 err = remove_xattr(c, host, inode, &nm);
529 /* If @i_nlink is 0, 'iput()' will delete the inode */
537 static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
540 const struct xattr *xattr;
544 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
545 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
546 strlen(xattr->name) + 1, GFP_NOFS);
551 strcpy(name, XATTR_SECURITY_PREFIX);
552 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
553 err = __ubifs_setxattr(inode, name, xattr->value,
554 xattr->value_len, 0, false);
563 int ubifs_init_security(struct inode *dentry, struct inode *inode,
564 const struct qstr *qstr)
568 err = security_inode_init_security(inode, dentry, qstr,
571 struct ubifs_info *c = dentry->i_sb->s_fs_info;
572 ubifs_err(c, "cannot initialize security for inode %lu, error %d",
578 static int ubifs_xattr_get(const struct xattr_handler *handler,
579 struct dentry *dentry, struct inode *inode,
580 const char *name, void *buffer, size_t size)
582 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
583 inode->i_ino, dentry, size);
585 name = xattr_full_name(handler, name);
586 return __ubifs_getxattr(inode, name, buffer, size);
589 static int ubifs_xattr_set(const struct xattr_handler *handler,
590 struct dentry *dentry, struct inode *inode,
591 const char *name, const void *value,
592 size_t size, int flags)
594 dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
595 name, inode->i_ino, dentry, size);
597 name = xattr_full_name(handler, name);
600 return __ubifs_setxattr(inode, name, value, size, flags,
603 return __ubifs_removexattr(inode, name);
606 static const struct xattr_handler ubifs_user_xattr_handler = {
607 .prefix = XATTR_USER_PREFIX,
608 .get = ubifs_xattr_get,
609 .set = ubifs_xattr_set,
612 static const struct xattr_handler ubifs_trusted_xattr_handler = {
613 .prefix = XATTR_TRUSTED_PREFIX,
614 .get = ubifs_xattr_get,
615 .set = ubifs_xattr_set,
618 static const struct xattr_handler ubifs_security_xattr_handler = {
619 .prefix = XATTR_SECURITY_PREFIX,
620 .get = ubifs_xattr_get,
621 .set = ubifs_xattr_set,
624 const struct xattr_handler *ubifs_xattr_handlers[] = {
625 &ubifs_user_xattr_handler,
626 &ubifs_trusted_xattr_handler,
627 &ubifs_security_xattr_handler,