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)
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)
122 err = ubifs_budget_space(c, &req);
126 inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
128 err = PTR_ERR(inode);
132 /* Re-define all operations to be "nothing" */
133 inode->i_mapping->a_ops = &empty_aops;
134 inode->i_op = &empty_iops;
135 inode->i_fop = &empty_fops;
137 inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME | S_NOQUOTA;
138 ui = ubifs_inode(inode);
140 ui->flags |= UBIFS_XATTR_FL;
141 ui->data = kmalloc(size, GFP_NOFS);
146 memcpy(ui->data, value, size);
147 inode->i_size = ui->ui_size = 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);
160 mutex_unlock(&host_ui->ui_mutex);
162 ubifs_release_budget(c, &req);
163 insert_inode_hash(inode);
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 host_ui->xattr_names -= nm->len;
172 mutex_unlock(&host_ui->ui_mutex);
174 make_bad_inode(inode);
177 ubifs_release_budget(c, &req);
182 * change_xattr - change an extended attribute.
183 * @c: UBIFS file-system description object
185 * @inode: extended attribute inode
186 * @value: extended attribute value
187 * @size: size of extended attribute value
189 * This helper function changes the value of extended attribute @inode with new
190 * data from @value. Returns zero in case of success and a negative error code
191 * in case of failure.
193 static int change_xattr(struct ubifs_info *c, struct inode *host,
194 struct inode *inode, const void *value, int size)
197 struct ubifs_inode *host_ui = ubifs_inode(host);
198 struct ubifs_inode *ui = ubifs_inode(inode);
199 struct ubifs_budget_req req = { .dirtied_ino = 2,
200 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
202 ubifs_assert(ui->data_len == inode->i_size);
203 err = ubifs_budget_space(c, &req);
208 ui->data = kmalloc(size, GFP_NOFS);
213 memcpy(ui->data, value, size);
214 inode->i_size = ui->ui_size = size;
217 mutex_lock(&host_ui->ui_mutex);
218 host->i_ctime = ubifs_current_time(host);
219 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
220 host_ui->xattr_size += CALC_XATTR_BYTES(size);
223 * It is important to write the host inode after the xattr inode
224 * because if the host inode gets synchronized (via 'fsync()'), then
225 * the extended attribute inode gets synchronized, because it goes
226 * before the host inode in the write-buffer.
228 err = ubifs_jnl_change_xattr(c, inode, host);
231 mutex_unlock(&host_ui->ui_mutex);
233 ubifs_release_budget(c, &req);
237 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
238 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
239 mutex_unlock(&host_ui->ui_mutex);
240 make_bad_inode(inode);
242 ubifs_release_budget(c, &req);
247 * check_namespace - check extended attribute name-space.
248 * @nm: extended attribute name
250 * This function makes sure the extended attribute name belongs to one of the
251 * supported extended attribute name-spaces. Returns name-space index in case
252 * of success and a negative error code in case of failure.
254 static int check_namespace(const struct qstr *nm)
258 if (nm->len > UBIFS_MAX_NLEN)
259 return -ENAMETOOLONG;
261 if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
262 XATTR_TRUSTED_PREFIX_LEN)) {
263 if (nm->name[sizeof(XATTR_TRUSTED_PREFIX) - 1] == '\0')
265 type = TRUSTED_XATTR;
266 } else if (!strncmp(nm->name, XATTR_USER_PREFIX,
267 XATTR_USER_PREFIX_LEN)) {
268 if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
271 } else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
272 XATTR_SECURITY_PREFIX_LEN)) {
273 if (nm->name[sizeof(XATTR_SECURITY_PREFIX) - 1] == '\0')
275 type = SECURITY_XATTR;
282 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
286 inode = ubifs_iget(c->vfs_sb, inum);
288 ubifs_err("dead extended attribute entry, error %d",
289 (int)PTR_ERR(inode));
292 if (ubifs_inode(inode)->xattr)
294 ubifs_err("corrupt extended attribute entry");
296 return ERR_PTR(-EINVAL);
299 int ubifs_setxattr(struct dentry *dentry, const char *name,
300 const void *value, size_t size, int flags)
302 struct inode *inode, *host = dentry->d_inode;
303 struct ubifs_info *c = host->i_sb->s_fs_info;
304 struct qstr nm = { .name = name, .len = strlen(name) };
305 struct ubifs_dent_node *xent;
309 dbg_gen("xattr '%s', host ino %lu ('%.*s'), size %zd", name,
310 host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
311 ubifs_assert(mutex_is_locked(&host->i_mutex));
313 if (size > UBIFS_MAX_INO_DATA)
316 type = check_namespace(&nm);
320 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
325 * The extended attribute entries are stored in LNC, so multiple
326 * look-ups do not involve reading the flash.
328 xent_key_init(c, &key, host->i_ino, &nm);
329 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
334 if (flags & XATTR_REPLACE)
335 /* We are asked not to create the xattr */
338 err = create_xattr(c, host, &nm, value, size);
342 if (flags & XATTR_CREATE) {
343 /* We are asked not to replace the xattr */
348 inode = iget_xattr(c, le64_to_cpu(xent->inum));
350 err = PTR_ERR(inode);
354 err = change_xattr(c, host, inode, value, size);
362 ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
365 struct inode *inode, *host = dentry->d_inode;
366 struct ubifs_info *c = host->i_sb->s_fs_info;
367 struct qstr nm = { .name = name, .len = strlen(name) };
368 struct ubifs_inode *ui;
369 struct ubifs_dent_node *xent;
373 dbg_gen("xattr '%s', ino %lu ('%.*s'), buf size %zd", name,
374 host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
376 err = check_namespace(&nm);
380 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
384 xent_key_init(c, &key, host->i_ino, &nm);
385 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
392 inode = iget_xattr(c, le64_to_cpu(xent->inum));
394 err = PTR_ERR(inode);
398 ui = ubifs_inode(inode);
399 ubifs_assert(inode->i_size == ui->data_len);
400 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
403 /* If @buf is %NULL we are supposed to return the length */
404 if (ui->data_len > size) {
405 dbg_err("buffer size %zd, xattr len %d",
411 memcpy(buf, ui->data, ui->data_len);
422 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
425 struct inode *host = dentry->d_inode;
426 struct ubifs_info *c = host->i_sb->s_fs_info;
427 struct ubifs_inode *host_ui = ubifs_inode(host);
428 struct ubifs_dent_node *xent, *pxent = NULL;
429 int err, len, written = 0;
430 struct qstr nm = { .name = NULL };
432 dbg_gen("ino %lu ('%.*s'), buffer size %zd", host->i_ino,
433 dentry->d_name.len, dentry->d_name.name, size);
435 len = host_ui->xattr_names + host_ui->xattr_cnt;
438 * We should return the minimum buffer size which will fit a
439 * null-terminated list of all the extended attribute names.
446 lowest_xent_key(c, &key, host->i_ino);
450 xent = ubifs_tnc_next_ent(c, &key, &nm);
456 nm.name = xent->name;
457 nm.len = le16_to_cpu(xent->nlen);
459 type = check_namespace(&nm);
460 if (unlikely(type < 0)) {
465 /* Show trusted namespace only for "power" users */
466 if (type != TRUSTED_XATTR || capable(CAP_SYS_ADMIN)) {
467 memcpy(buffer + written, nm.name, nm.len + 1);
468 written += nm.len + 1;
473 key_read(c, &xent->key, &key);
477 if (err != -ENOENT) {
478 ubifs_err("cannot find next direntry, error %d", err);
482 ubifs_assert(written <= size);
486 static int remove_xattr(struct ubifs_info *c, struct inode *host,
487 struct inode *inode, const struct qstr *nm)
490 struct ubifs_inode *host_ui = ubifs_inode(host);
491 struct ubifs_inode *ui = ubifs_inode(inode);
492 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
493 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
495 ubifs_assert(ui->data_len == inode->i_size);
497 err = ubifs_budget_space(c, &req);
501 mutex_lock(&host_ui->ui_mutex);
502 host->i_ctime = ubifs_current_time(host);
503 host_ui->xattr_cnt -= 1;
504 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
505 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
506 host_ui->xattr_names -= nm->len;
508 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
511 mutex_unlock(&host_ui->ui_mutex);
513 ubifs_release_budget(c, &req);
517 host_ui->xattr_cnt += 1;
518 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
519 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
520 host_ui->xattr_names += nm->len;
521 mutex_unlock(&host_ui->ui_mutex);
522 ubifs_release_budget(c, &req);
523 make_bad_inode(inode);
527 int ubifs_removexattr(struct dentry *dentry, const char *name)
529 struct inode *inode, *host = dentry->d_inode;
530 struct ubifs_info *c = host->i_sb->s_fs_info;
531 struct qstr nm = { .name = name, .len = strlen(name) };
532 struct ubifs_dent_node *xent;
536 dbg_gen("xattr '%s', ino %lu ('%.*s')", name,
537 host->i_ino, dentry->d_name.len, dentry->d_name.name);
538 ubifs_assert(mutex_is_locked(&host->i_mutex));
540 err = check_namespace(&nm);
544 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
548 xent_key_init(c, &key, host->i_ino, &nm);
549 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
556 inode = iget_xattr(c, le64_to_cpu(xent->inum));
558 err = PTR_ERR(inode);
562 ubifs_assert(inode->i_nlink == 1);
564 err = remove_xattr(c, host, inode, &nm);
568 /* If @i_nlink is 0, 'iput()' will delete the inode */