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 host_ui->xattr_names -= nm->len;
177 mutex_unlock(&host_ui->ui_mutex);
179 make_bad_inode(inode);
182 ubifs_release_budget(c, &req);
187 * change_xattr - change an extended attribute.
188 * @c: UBIFS file-system description object
190 * @inode: extended attribute inode
191 * @value: extended attribute value
192 * @size: size of extended attribute value
194 * This helper function changes the value of extended attribute @inode with new
195 * data from @value. Returns zero in case of success and a negative error code
196 * in case of failure.
198 static int change_xattr(struct ubifs_info *c, struct inode *host,
199 struct inode *inode, const void *value, int size)
202 struct ubifs_inode *host_ui = ubifs_inode(host);
203 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;
223 mutex_unlock(&ui->ui_mutex);
225 mutex_lock(&host_ui->ui_mutex);
226 host->i_ctime = ubifs_current_time(host);
227 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
228 host_ui->xattr_size += CALC_XATTR_BYTES(size);
231 * It is important to write the host inode after the xattr inode
232 * because if the host inode gets synchronized (via 'fsync()'), then
233 * the extended attribute inode gets synchronized, because it goes
234 * before the host inode in the write-buffer.
236 err = ubifs_jnl_change_xattr(c, inode, host);
239 mutex_unlock(&host_ui->ui_mutex);
241 ubifs_release_budget(c, &req);
245 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
246 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
247 mutex_unlock(&host_ui->ui_mutex);
248 make_bad_inode(inode);
250 ubifs_release_budget(c, &req);
255 * check_namespace - check extended attribute name-space.
256 * @nm: extended attribute name
258 * This function makes sure the extended attribute name belongs to one of the
259 * supported extended attribute name-spaces. Returns name-space index in case
260 * of success and a negative error code in case of failure.
262 static int check_namespace(const struct qstr *nm)
266 if (nm->len > UBIFS_MAX_NLEN)
267 return -ENAMETOOLONG;
269 if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
270 XATTR_TRUSTED_PREFIX_LEN)) {
271 if (nm->name[sizeof(XATTR_TRUSTED_PREFIX) - 1] == '\0')
273 type = TRUSTED_XATTR;
274 } else if (!strncmp(nm->name, XATTR_USER_PREFIX,
275 XATTR_USER_PREFIX_LEN)) {
276 if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
279 } else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
280 XATTR_SECURITY_PREFIX_LEN)) {
281 if (nm->name[sizeof(XATTR_SECURITY_PREFIX) - 1] == '\0')
283 type = SECURITY_XATTR;
290 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
294 inode = ubifs_iget(c->vfs_sb, inum);
296 ubifs_err(c, "dead extended attribute entry, error %d",
297 (int)PTR_ERR(inode));
300 if (ubifs_inode(inode)->xattr)
302 ubifs_err(c, "corrupt extended attribute entry");
304 return ERR_PTR(-EINVAL);
307 static int setxattr(struct inode *host, const char *name, const void *value,
308 size_t size, int flags)
311 struct ubifs_info *c = host->i_sb->s_fs_info;
312 struct qstr nm = QSTR_INIT(name, strlen(name));
313 struct ubifs_dent_node *xent;
317 ubifs_assert(mutex_is_locked(&host->i_mutex));
319 if (size > UBIFS_MAX_INO_DATA)
322 type = check_namespace(&nm);
326 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
331 * The extended attribute entries are stored in LNC, so multiple
332 * look-ups do not involve reading the flash.
334 xent_key_init(c, &key, host->i_ino, &nm);
335 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
340 if (flags & XATTR_REPLACE)
341 /* We are asked not to create the xattr */
344 err = create_xattr(c, host, &nm, value, size);
348 if (flags & XATTR_CREATE) {
349 /* We are asked not to replace the xattr */
354 inode = iget_xattr(c, le64_to_cpu(xent->inum));
356 err = PTR_ERR(inode);
360 err = change_xattr(c, host, inode, value, size);
368 int ubifs_setxattr(struct dentry *dentry, const char *name,
369 const void *value, size_t size, int flags)
371 dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
372 name, d_inode(dentry)->i_ino, dentry, size);
374 return setxattr(d_inode(dentry), name, value, size, flags);
377 ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
380 struct inode *inode, *host = d_inode(dentry);
381 struct ubifs_info *c = host->i_sb->s_fs_info;
382 struct qstr nm = QSTR_INIT(name, strlen(name));
383 struct ubifs_inode *ui;
384 struct ubifs_dent_node *xent;
388 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
389 host->i_ino, dentry, size);
391 err = check_namespace(&nm);
395 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
399 xent_key_init(c, &key, host->i_ino, &nm);
400 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
407 inode = iget_xattr(c, le64_to_cpu(xent->inum));
409 err = PTR_ERR(inode);
413 ui = ubifs_inode(inode);
414 ubifs_assert(inode->i_size == ui->data_len);
415 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
417 mutex_lock(&ui->ui_mutex);
419 /* If @buf is %NULL we are supposed to return the length */
420 if (ui->data_len > size) {
421 ubifs_err(c, "buffer size %zd, xattr len %d",
427 memcpy(buf, ui->data, ui->data_len);
432 mutex_unlock(&ui->ui_mutex);
439 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
442 struct inode *host = d_inode(dentry);
443 struct ubifs_info *c = host->i_sb->s_fs_info;
444 struct ubifs_inode *host_ui = ubifs_inode(host);
445 struct ubifs_dent_node *xent, *pxent = NULL;
446 int err, len, written = 0;
447 struct qstr nm = { .name = NULL };
449 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
452 len = host_ui->xattr_names + host_ui->xattr_cnt;
455 * We should return the minimum buffer size which will fit a
456 * null-terminated list of all the extended attribute names.
463 lowest_xent_key(c, &key, host->i_ino);
467 xent = ubifs_tnc_next_ent(c, &key, &nm);
473 nm.name = xent->name;
474 nm.len = le16_to_cpu(xent->nlen);
476 type = check_namespace(&nm);
477 if (unlikely(type < 0)) {
482 /* Show trusted namespace only for "power" users */
483 if (type != TRUSTED_XATTR || capable(CAP_SYS_ADMIN)) {
484 memcpy(buffer + written, nm.name, nm.len + 1);
485 written += nm.len + 1;
490 key_read(c, &xent->key, &key);
494 if (err != -ENOENT) {
495 ubifs_err(c, "cannot find next direntry, error %d", err);
499 ubifs_assert(written <= size);
503 static int remove_xattr(struct ubifs_info *c, struct inode *host,
504 struct inode *inode, const struct qstr *nm)
507 struct ubifs_inode *host_ui = ubifs_inode(host);
508 struct ubifs_inode *ui = ubifs_inode(inode);
509 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
510 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
512 ubifs_assert(ui->data_len == inode->i_size);
514 err = ubifs_budget_space(c, &req);
518 mutex_lock(&host_ui->ui_mutex);
519 host->i_ctime = ubifs_current_time(host);
520 host_ui->xattr_cnt -= 1;
521 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
522 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
523 host_ui->xattr_names -= nm->len;
525 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
528 mutex_unlock(&host_ui->ui_mutex);
530 ubifs_release_budget(c, &req);
534 host_ui->xattr_cnt += 1;
535 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
536 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
537 host_ui->xattr_names += nm->len;
538 mutex_unlock(&host_ui->ui_mutex);
539 ubifs_release_budget(c, &req);
540 make_bad_inode(inode);
544 int ubifs_removexattr(struct dentry *dentry, const char *name)
546 struct inode *inode, *host = d_inode(dentry);
547 struct ubifs_info *c = host->i_sb->s_fs_info;
548 struct qstr nm = QSTR_INIT(name, strlen(name));
549 struct ubifs_dent_node *xent;
553 dbg_gen("xattr '%s', ino %lu ('%pd')", name,
554 host->i_ino, dentry);
555 ubifs_assert(mutex_is_locked(&host->i_mutex));
557 err = check_namespace(&nm);
561 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
565 xent_key_init(c, &key, host->i_ino, &nm);
566 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
573 inode = iget_xattr(c, le64_to_cpu(xent->inum));
575 err = PTR_ERR(inode);
579 ubifs_assert(inode->i_nlink == 1);
581 err = remove_xattr(c, host, inode, &nm);
585 /* If @i_nlink is 0, 'iput()' will delete the inode */
593 static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
596 const struct xattr *xattr;
600 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
601 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
602 strlen(xattr->name) + 1, GFP_NOFS);
607 strcpy(name, XATTR_SECURITY_PREFIX);
608 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
609 err = setxattr(inode, name, xattr->value, xattr->value_len, 0);
618 int ubifs_init_security(struct inode *dentry, struct inode *inode,
619 const struct qstr *qstr)
623 err = security_inode_init_security(inode, dentry, qstr,
626 struct ubifs_info *c = dentry->i_sb->s_fs_info;
627 ubifs_err(c, "cannot initialize security for inode %lu, error %d",