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 fscrypt_name *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 + fname_len(nm) + 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 = current_time(host);
156 host_ui->xattr_cnt += 1;
157 host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
158 host_ui->xattr_size += CALC_XATTR_BYTES(size);
159 host_ui->xattr_names += fname_len(nm);
162 * We handle UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT here because we
163 * have to set the UBIFS_CRYPT_FL flag on the host inode.
164 * To avoid multiple updates of the same inode in the same operation,
167 if (strcmp(fname_name(nm), UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
168 host_ui->flags |= UBIFS_CRYPT_FL;
170 err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
173 mutex_unlock(&host_ui->ui_mutex);
175 ubifs_release_budget(c, &req);
176 insert_inode_hash(inode);
181 host_ui->xattr_cnt -= 1;
182 host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
183 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
184 host_ui->xattr_names -= fname_len(nm);
185 host_ui->flags &= ~UBIFS_CRYPT_FL;
186 mutex_unlock(&host_ui->ui_mutex);
188 make_bad_inode(inode);
191 ubifs_release_budget(c, &req);
196 * change_xattr - change an extended attribute.
197 * @c: UBIFS file-system description object
199 * @inode: extended attribute inode
200 * @value: extended attribute value
201 * @size: size of extended attribute value
203 * This helper function changes the value of extended attribute @inode with new
204 * data from @value. Returns zero in case of success and a negative error code
205 * in case of failure.
207 static int change_xattr(struct ubifs_info *c, struct inode *host,
208 struct inode *inode, const void *value, int size)
211 struct ubifs_inode *host_ui = ubifs_inode(host);
212 struct ubifs_inode *ui = ubifs_inode(inode);
215 struct ubifs_budget_req req = { .dirtied_ino = 2,
216 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
218 ubifs_assert(ui->data_len == inode->i_size);
219 err = ubifs_budget_space(c, &req);
223 buf = kmemdup(value, size, GFP_NOFS);
228 mutex_lock(&ui->ui_mutex);
231 inode->i_size = ui->ui_size = size;
232 old_size = ui->data_len;
234 mutex_unlock(&ui->ui_mutex);
236 mutex_lock(&host_ui->ui_mutex);
237 host->i_ctime = current_time(host);
238 host_ui->xattr_size -= CALC_XATTR_BYTES(old_size);
239 host_ui->xattr_size += CALC_XATTR_BYTES(size);
242 * It is important to write the host inode after the xattr inode
243 * because if the host inode gets synchronized (via 'fsync()'), then
244 * the extended attribute inode gets synchronized, because it goes
245 * before the host inode in the write-buffer.
247 err = ubifs_jnl_change_xattr(c, inode, host);
250 mutex_unlock(&host_ui->ui_mutex);
252 ubifs_release_budget(c, &req);
256 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
257 host_ui->xattr_size += CALC_XATTR_BYTES(old_size);
258 mutex_unlock(&host_ui->ui_mutex);
259 make_bad_inode(inode);
261 ubifs_release_budget(c, &req);
265 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
269 inode = ubifs_iget(c->vfs_sb, inum);
271 ubifs_err(c, "dead extended attribute entry, error %d",
272 (int)PTR_ERR(inode));
275 if (ubifs_inode(inode)->xattr)
277 ubifs_err(c, "corrupt extended attribute entry");
279 return ERR_PTR(-EINVAL);
282 int ubifs_xattr_set(struct inode *host, const char *name, const void *value,
283 size_t size, int flags, bool check_lock)
286 struct ubifs_info *c = host->i_sb->s_fs_info;
287 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
288 struct ubifs_dent_node *xent;
293 ubifs_assert(inode_is_locked(host));
295 if (size > UBIFS_MAX_INO_DATA)
298 if (fname_len(&nm) > UBIFS_MAX_NLEN)
299 return -ENAMETOOLONG;
301 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
306 * The extended attribute entries are stored in LNC, so multiple
307 * look-ups do not involve reading the flash.
309 xent_key_init(c, &key, host->i_ino, &nm);
310 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
315 if (flags & XATTR_REPLACE)
316 /* We are asked not to create the xattr */
319 err = create_xattr(c, host, &nm, value, size);
323 if (flags & XATTR_CREATE) {
324 /* We are asked not to replace the xattr */
329 inode = iget_xattr(c, le64_to_cpu(xent->inum));
331 err = PTR_ERR(inode);
335 err = change_xattr(c, host, inode, value, size);
343 ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf,
347 struct ubifs_info *c = host->i_sb->s_fs_info;
348 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
349 struct ubifs_inode *ui;
350 struct ubifs_dent_node *xent;
354 if (fname_len(&nm) > UBIFS_MAX_NLEN)
355 return -ENAMETOOLONG;
357 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
361 xent_key_init(c, &key, host->i_ino, &nm);
362 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
369 inode = iget_xattr(c, le64_to_cpu(xent->inum));
371 err = PTR_ERR(inode);
375 ui = ubifs_inode(inode);
376 ubifs_assert(inode->i_size == ui->data_len);
377 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
379 mutex_lock(&ui->ui_mutex);
381 /* If @buf is %NULL we are supposed to return the length */
382 if (ui->data_len > size) {
383 ubifs_err(c, "buffer size %zd, xattr len %d",
389 memcpy(buf, ui->data, ui->data_len);
394 mutex_unlock(&ui->ui_mutex);
401 static bool xattr_visible(const char *name)
403 /* File encryption related xattrs are for internal use only */
404 if (strcmp(name, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
407 /* Show trusted namespace only for "power" users */
408 if (strncmp(name, XATTR_TRUSTED_PREFIX,
409 XATTR_TRUSTED_PREFIX_LEN) == 0 && !capable(CAP_SYS_ADMIN))
415 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
418 struct inode *host = d_inode(dentry);
419 struct ubifs_info *c = host->i_sb->s_fs_info;
420 struct ubifs_inode *host_ui = ubifs_inode(host);
421 struct ubifs_dent_node *xent, *pxent = NULL;
422 int err, len, written = 0;
423 struct fscrypt_name nm = {0};
425 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
428 len = host_ui->xattr_names + host_ui->xattr_cnt;
431 * We should return the minimum buffer size which will fit a
432 * null-terminated list of all the extended attribute names.
439 lowest_xent_key(c, &key, host->i_ino);
441 xent = ubifs_tnc_next_ent(c, &key, &nm);
447 fname_name(&nm) = xent->name;
448 fname_len(&nm) = le16_to_cpu(xent->nlen);
450 if (xattr_visible(xent->name)) {
451 memcpy(buffer + written, fname_name(&nm), fname_len(&nm) + 1);
452 written += fname_len(&nm) + 1;
457 key_read(c, &xent->key, &key);
461 if (err != -ENOENT) {
462 ubifs_err(c, "cannot find next direntry, error %d", err);
466 ubifs_assert(written <= size);
470 static int remove_xattr(struct ubifs_info *c, struct inode *host,
471 struct inode *inode, const struct fscrypt_name *nm)
474 struct ubifs_inode *host_ui = ubifs_inode(host);
475 struct ubifs_inode *ui = ubifs_inode(inode);
476 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
477 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
479 ubifs_assert(ui->data_len == inode->i_size);
481 err = ubifs_budget_space(c, &req);
485 mutex_lock(&host_ui->ui_mutex);
486 host->i_ctime = current_time(host);
487 host_ui->xattr_cnt -= 1;
488 host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
489 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
490 host_ui->xattr_names -= fname_len(nm);
492 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
495 mutex_unlock(&host_ui->ui_mutex);
497 ubifs_release_budget(c, &req);
501 host_ui->xattr_cnt += 1;
502 host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
503 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
504 host_ui->xattr_names += fname_len(nm);
505 mutex_unlock(&host_ui->ui_mutex);
506 ubifs_release_budget(c, &req);
507 make_bad_inode(inode);
512 * ubifs_evict_xattr_inode - Evict an xattr inode.
513 * @c: UBIFS file-system description object
514 * @xattr_inum: xattr inode number
516 * When an inode that hosts xattrs is being removed we have to make sure
517 * that cached inodes of the xattrs also get removed from the inode cache
518 * otherwise we'd waste memory. This function looks up an inode from the
519 * inode cache and clears the link counter such that iput() will evict
522 void ubifs_evict_xattr_inode(struct ubifs_info *c, ino_t xattr_inum)
526 inode = ilookup(c->vfs_sb, xattr_inum);
533 static int ubifs_xattr_remove(struct inode *host, const char *name)
536 struct ubifs_info *c = host->i_sb->s_fs_info;
537 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
538 struct ubifs_dent_node *xent;
542 ubifs_assert(inode_is_locked(host));
544 if (fname_len(&nm) > UBIFS_MAX_NLEN)
545 return -ENAMETOOLONG;
547 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
551 xent_key_init(c, &key, host->i_ino, &nm);
552 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
559 inode = iget_xattr(c, le64_to_cpu(xent->inum));
561 err = PTR_ERR(inode);
565 ubifs_assert(inode->i_nlink == 1);
567 err = remove_xattr(c, host, inode, &nm);
571 /* If @i_nlink is 0, 'iput()' will delete the inode */
579 #ifdef CONFIG_UBIFS_FS_SECURITY
580 static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
583 const struct xattr *xattr;
587 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
588 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
589 strlen(xattr->name) + 1, GFP_NOFS);
594 strcpy(name, XATTR_SECURITY_PREFIX);
595 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
597 * creating a new inode without holding the inode rwsem,
598 * no need to check whether inode is locked.
600 err = ubifs_xattr_set(inode, name, xattr->value,
601 xattr->value_len, 0, false);
610 int ubifs_init_security(struct inode *dentry, struct inode *inode,
611 const struct qstr *qstr)
615 err = security_inode_init_security(inode, dentry, qstr,
618 struct ubifs_info *c = dentry->i_sb->s_fs_info;
619 ubifs_err(c, "cannot initialize security for inode %lu, error %d",
626 static int xattr_get(const struct xattr_handler *handler,
627 struct dentry *dentry, struct inode *inode,
628 const char *name, void *buffer, size_t size)
630 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
631 inode->i_ino, dentry, size);
633 name = xattr_full_name(handler, name);
634 return ubifs_xattr_get(inode, name, buffer, size);
637 static int xattr_set(const struct xattr_handler *handler,
638 struct dentry *dentry, struct inode *inode,
639 const char *name, const void *value,
640 size_t size, int flags)
642 dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
643 name, inode->i_ino, dentry, size);
645 name = xattr_full_name(handler, name);
648 return ubifs_xattr_set(inode, name, value, size, flags, true);
650 return ubifs_xattr_remove(inode, name);
653 static const struct xattr_handler ubifs_user_xattr_handler = {
654 .prefix = XATTR_USER_PREFIX,
659 static const struct xattr_handler ubifs_trusted_xattr_handler = {
660 .prefix = XATTR_TRUSTED_PREFIX,
665 #ifdef CONFIG_UBIFS_FS_SECURITY
666 static const struct xattr_handler ubifs_security_xattr_handler = {
667 .prefix = XATTR_SECURITY_PREFIX,
673 const struct xattr_handler *ubifs_xattr_handlers[] = {
674 &ubifs_user_xattr_handler,
675 &ubifs_trusted_xattr_handler,
676 #ifdef CONFIG_UBIFS_FS_SECURITY
677 &ubifs_security_xattr_handler,