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 mutex_unlock(&host_ui->ui_mutex);
173 make_bad_inode(inode);
176 ubifs_release_budget(c, &req);
181 * change_xattr - change an extended attribute.
182 * @c: UBIFS file-system description object
184 * @inode: extended attribute inode
185 * @value: extended attribute value
186 * @size: size of extended attribute value
188 * This helper function changes the value of extended attribute @inode with new
189 * data from @value. Returns zero in case of success and a negative error code
190 * in case of failure.
192 static int change_xattr(struct ubifs_info *c, struct inode *host,
193 struct inode *inode, const void *value, int size)
196 struct ubifs_inode *host_ui = ubifs_inode(host);
197 struct ubifs_inode *ui = ubifs_inode(inode);
198 struct ubifs_budget_req req = { .dirtied_ino = 2,
199 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
201 ubifs_assert(ui->data_len == inode->i_size);
202 err = ubifs_budget_space(c, &req);
207 ui->data = kmalloc(size, GFP_NOFS);
212 memcpy(ui->data, value, size);
213 inode->i_size = ui->ui_size = size;
216 mutex_lock(&host_ui->ui_mutex);
217 host->i_ctime = ubifs_current_time(host);
218 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
219 host_ui->xattr_size += CALC_XATTR_BYTES(size);
222 * It is important to write the host inode after the xattr inode
223 * because if the host inode gets synchronized (via 'fsync()'), then
224 * the extended attribute inode gets synchronized, because it goes
225 * before the host inode in the write-buffer.
227 err = ubifs_jnl_change_xattr(c, inode, host);
230 mutex_unlock(&host_ui->ui_mutex);
232 ubifs_release_budget(c, &req);
236 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
237 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
238 mutex_unlock(&host_ui->ui_mutex);
239 make_bad_inode(inode);
241 ubifs_release_budget(c, &req);
246 * check_namespace - check extended attribute name-space.
247 * @nm: extended attribute name
249 * This function makes sure the extended attribute name belongs to one of the
250 * supported extended attribute name-spaces. Returns name-space index in case
251 * of success and a negative error code in case of failure.
253 static int check_namespace(const struct qstr *nm)
257 if (nm->len > UBIFS_MAX_NLEN)
258 return -ENAMETOOLONG;
260 if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
261 XATTR_TRUSTED_PREFIX_LEN)) {
262 if (nm->name[sizeof(XATTR_TRUSTED_PREFIX) - 1] == '\0')
264 type = TRUSTED_XATTR;
265 } else if (!strncmp(nm->name, XATTR_USER_PREFIX,
266 XATTR_USER_PREFIX_LEN)) {
267 if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
270 } else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
271 XATTR_SECURITY_PREFIX_LEN)) {
272 if (nm->name[sizeof(XATTR_SECURITY_PREFIX) - 1] == '\0')
274 type = SECURITY_XATTR;
281 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
285 inode = ubifs_iget(c->vfs_sb, inum);
287 ubifs_err("dead extended attribute entry, error %d",
288 (int)PTR_ERR(inode));
291 if (ubifs_inode(inode)->xattr)
293 ubifs_err("corrupt extended attribute entry");
295 return ERR_PTR(-EINVAL);
298 int ubifs_setxattr(struct dentry *dentry, const char *name,
299 const void *value, size_t size, int flags)
301 struct inode *inode, *host = dentry->d_inode;
302 struct ubifs_info *c = host->i_sb->s_fs_info;
303 struct qstr nm = { .name = name, .len = strlen(name) };
304 struct ubifs_dent_node *xent;
308 dbg_gen("xattr '%s', host ino %lu ('%.*s'), size %zd", name,
309 host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
310 ubifs_assert(mutex_is_locked(&host->i_mutex));
312 if (size > UBIFS_MAX_INO_DATA)
315 type = check_namespace(&nm);
319 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
324 * The extended attribute entries are stored in LNC, so multiple
325 * look-ups do not involve reading the flash.
327 xent_key_init(c, &key, host->i_ino, &nm);
328 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
333 if (flags & XATTR_REPLACE)
334 /* We are asked not to create the xattr */
337 err = create_xattr(c, host, &nm, value, size);
341 if (flags & XATTR_CREATE) {
342 /* We are asked not to replace the xattr */
347 inode = iget_xattr(c, le64_to_cpu(xent->inum));
349 err = PTR_ERR(inode);
353 err = change_xattr(c, host, inode, value, size);
361 ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
364 struct inode *inode, *host = dentry->d_inode;
365 struct ubifs_info *c = host->i_sb->s_fs_info;
366 struct qstr nm = { .name = name, .len = strlen(name) };
367 struct ubifs_inode *ui;
368 struct ubifs_dent_node *xent;
372 dbg_gen("xattr '%s', ino %lu ('%.*s'), buf size %zd", name,
373 host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
375 err = check_namespace(&nm);
379 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
383 xent_key_init(c, &key, host->i_ino, &nm);
384 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
391 inode = iget_xattr(c, le64_to_cpu(xent->inum));
393 err = PTR_ERR(inode);
397 ui = ubifs_inode(inode);
398 ubifs_assert(inode->i_size == ui->data_len);
399 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
402 /* If @buf is %NULL we are supposed to return the length */
403 if (ui->data_len > size) {
404 dbg_err("buffer size %zd, xattr len %d",
410 memcpy(buf, ui->data, ui->data_len);
421 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
424 struct inode *host = dentry->d_inode;
425 struct ubifs_info *c = host->i_sb->s_fs_info;
426 struct ubifs_inode *host_ui = ubifs_inode(host);
427 struct ubifs_dent_node *xent, *pxent = NULL;
428 int err, len, written = 0;
429 struct qstr nm = { .name = NULL };
431 dbg_gen("ino %lu ('%.*s'), buffer size %zd", host->i_ino,
432 dentry->d_name.len, dentry->d_name.name, size);
434 len = host_ui->xattr_names + host_ui->xattr_cnt;
437 * We should return the minimum buffer size which will fit a
438 * null-terminated list of all the extended attribute names.
445 lowest_xent_key(c, &key, host->i_ino);
449 xent = ubifs_tnc_next_ent(c, &key, &nm);
455 nm.name = xent->name;
456 nm.len = le16_to_cpu(xent->nlen);
458 type = check_namespace(&nm);
459 if (unlikely(type < 0)) {
464 /* Show trusted namespace only for "power" users */
465 if (type != TRUSTED_XATTR || capable(CAP_SYS_ADMIN)) {
466 memcpy(buffer + written, nm.name, nm.len + 1);
467 written += nm.len + 1;
472 key_read(c, &xent->key, &key);
476 if (err != -ENOENT) {
477 ubifs_err("cannot find next direntry, error %d", err);
481 ubifs_assert(written <= size);
485 static int remove_xattr(struct ubifs_info *c, struct inode *host,
486 struct inode *inode, const struct qstr *nm)
489 struct ubifs_inode *host_ui = ubifs_inode(host);
490 struct ubifs_inode *ui = ubifs_inode(inode);
491 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
492 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
494 ubifs_assert(ui->data_len == inode->i_size);
496 err = ubifs_budget_space(c, &req);
500 mutex_lock(&host_ui->ui_mutex);
501 host->i_ctime = ubifs_current_time(host);
502 host_ui->xattr_cnt -= 1;
503 host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
504 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
505 host_ui->xattr_names -= nm->len;
507 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
510 mutex_unlock(&host_ui->ui_mutex);
512 ubifs_release_budget(c, &req);
516 host_ui->xattr_cnt += 1;
517 host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
518 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
519 mutex_unlock(&host_ui->ui_mutex);
520 ubifs_release_budget(c, &req);
521 make_bad_inode(inode);
525 int ubifs_removexattr(struct dentry *dentry, const char *name)
527 struct inode *inode, *host = dentry->d_inode;
528 struct ubifs_info *c = host->i_sb->s_fs_info;
529 struct qstr nm = { .name = name, .len = strlen(name) };
530 struct ubifs_dent_node *xent;
534 dbg_gen("xattr '%s', ino %lu ('%.*s')", name,
535 host->i_ino, dentry->d_name.len, dentry->d_name.name);
536 ubifs_assert(mutex_is_locked(&host->i_mutex));
538 err = check_namespace(&nm);
542 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
546 xent_key_init(c, &key, host->i_ino, &nm);
547 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
554 inode = iget_xattr(c, le64_to_cpu(xent->inum));
556 err = PTR_ERR(inode);
560 ubifs_assert(inode->i_nlink == 1);
562 err = remove_xattr(c, host, inode, &nm);
566 /* If @i_nlink is 0, 'iput()' will delete the inode */