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 * Extended attribute type constants.
66 * USER_XATTR: user extended attribute ("user.*")
67 * TRUSTED_XATTR: trusted extended attribute ("trusted.*)
68 * SECURITY_XATTR: security extended attribute ("security.*")
76 static const struct inode_operations empty_iops;
77 static const struct file_operations empty_fops;
80 * create_xattr - create an extended attribute.
81 * @c: UBIFS file-system description object
83 * @nm: extended attribute name
84 * @value: extended attribute value
85 * @size: size of extended attribute value
87 * This is a helper function which creates an extended attribute of name @nm
88 * and value @value for inode @host. The host inode is also updated on flash
89 * because the ctime and extended attribute accounting data changes. This
90 * function returns zero in case of success and a negative error code in case
93 static int create_xattr(struct ubifs_info *c, struct inode *host,
94 const struct fscrypt_name *nm, const void *value, int size)
98 struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
99 struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
100 .new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
101 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
103 if (host_ui->xattr_cnt >= ubifs_xattr_max_cnt(c)) {
104 ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
105 host->i_ino, host_ui->xattr_cnt);
109 * Linux limits the maximum size of the extended attribute names list
110 * to %XATTR_LIST_MAX. This means we should not allow creating more
111 * extended attributes if the name list becomes larger. This limitation
112 * is artificial for UBIFS, though.
114 names_len = host_ui->xattr_names + host_ui->xattr_cnt + fname_len(nm) + 1;
115 if (names_len > XATTR_LIST_MAX) {
116 ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
117 host->i_ino, names_len, XATTR_LIST_MAX);
121 err = ubifs_budget_space(c, &req);
125 inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
127 err = PTR_ERR(inode);
131 /* Re-define all operations to be "nothing" */
132 inode->i_mapping->a_ops = &empty_aops;
133 inode->i_op = &empty_iops;
134 inode->i_fop = &empty_fops;
136 inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME;
137 ui = ubifs_inode(inode);
139 ui->flags |= UBIFS_XATTR_FL;
140 ui->data = kmemdup(value, size, GFP_NOFS);
145 inode->i_size = ui->ui_size = size;
148 mutex_lock(&host_ui->ui_mutex);
149 host->i_ctime = current_time(host);
150 host_ui->xattr_cnt += 1;
151 host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
152 host_ui->xattr_size += CALC_XATTR_BYTES(size);
153 host_ui->xattr_names += fname_len(nm);
156 * We handle UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT here because we
157 * have to set the UBIFS_CRYPT_FL flag on the host inode.
158 * To avoid multiple updates of the same inode in the same operation,
161 if (strcmp(fname_name(nm), UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
162 host_ui->flags |= UBIFS_CRYPT_FL;
164 err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
167 ubifs_set_inode_flags(host);
168 mutex_unlock(&host_ui->ui_mutex);
170 ubifs_release_budget(c, &req);
171 insert_inode_hash(inode);
176 host_ui->xattr_cnt -= 1;
177 host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
178 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
179 host_ui->xattr_names -= fname_len(nm);
180 host_ui->flags &= ~UBIFS_CRYPT_FL;
181 mutex_unlock(&host_ui->ui_mutex);
183 make_bad_inode(inode);
186 ubifs_release_budget(c, &req);
191 * change_xattr - change an extended attribute.
192 * @c: UBIFS file-system description object
194 * @inode: extended attribute inode
195 * @value: extended attribute value
196 * @size: size of extended attribute value
198 * This helper function changes the value of extended attribute @inode with new
199 * data from @value. Returns zero in case of success and a negative error code
200 * in case of failure.
202 static int change_xattr(struct ubifs_info *c, struct inode *host,
203 struct inode *inode, const void *value, int size)
206 struct ubifs_inode *host_ui = ubifs_inode(host);
207 struct ubifs_inode *ui = ubifs_inode(inode);
210 struct ubifs_budget_req req = { .dirtied_ino = 2,
211 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
213 ubifs_assert(c, ui->data_len == inode->i_size);
214 err = ubifs_budget_space(c, &req);
218 buf = kmemdup(value, size, GFP_NOFS);
223 mutex_lock(&ui->ui_mutex);
226 inode->i_size = ui->ui_size = size;
227 old_size = ui->data_len;
229 mutex_unlock(&ui->ui_mutex);
231 mutex_lock(&host_ui->ui_mutex);
232 host->i_ctime = current_time(host);
233 host_ui->xattr_size -= CALC_XATTR_BYTES(old_size);
234 host_ui->xattr_size += CALC_XATTR_BYTES(size);
237 * It is important to write the host inode after the xattr inode
238 * because if the host inode gets synchronized (via 'fsync()'), then
239 * the extended attribute inode gets synchronized, because it goes
240 * before the host inode in the write-buffer.
242 err = ubifs_jnl_change_xattr(c, inode, host);
245 mutex_unlock(&host_ui->ui_mutex);
247 ubifs_release_budget(c, &req);
251 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
252 host_ui->xattr_size += CALC_XATTR_BYTES(old_size);
253 mutex_unlock(&host_ui->ui_mutex);
254 make_bad_inode(inode);
256 ubifs_release_budget(c, &req);
260 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
264 inode = ubifs_iget(c->vfs_sb, inum);
266 ubifs_err(c, "dead extended attribute entry, error %d",
267 (int)PTR_ERR(inode));
270 if (ubifs_inode(inode)->xattr)
272 ubifs_err(c, "corrupt extended attribute entry");
274 return ERR_PTR(-EINVAL);
277 int ubifs_xattr_set(struct inode *host, const char *name, const void *value,
278 size_t size, int flags, bool check_lock)
281 struct ubifs_info *c = host->i_sb->s_fs_info;
282 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
283 struct ubifs_dent_node *xent;
288 ubifs_assert(c, inode_is_locked(host));
290 if (size > UBIFS_MAX_INO_DATA)
293 if (fname_len(&nm) > UBIFS_MAX_NLEN)
294 return -ENAMETOOLONG;
296 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
301 * The extended attribute entries are stored in LNC, so multiple
302 * look-ups do not involve reading the flash.
304 xent_key_init(c, &key, host->i_ino, &nm);
305 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
310 if (flags & XATTR_REPLACE)
311 /* We are asked not to create the xattr */
314 err = create_xattr(c, host, &nm, value, size);
318 if (flags & XATTR_CREATE) {
319 /* We are asked not to replace the xattr */
324 inode = iget_xattr(c, le64_to_cpu(xent->inum));
326 err = PTR_ERR(inode);
330 err = change_xattr(c, host, inode, value, size);
338 ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf,
342 struct ubifs_info *c = host->i_sb->s_fs_info;
343 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
344 struct ubifs_inode *ui;
345 struct ubifs_dent_node *xent;
349 if (fname_len(&nm) > UBIFS_MAX_NLEN)
350 return -ENAMETOOLONG;
352 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
356 xent_key_init(c, &key, host->i_ino, &nm);
357 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
364 inode = iget_xattr(c, le64_to_cpu(xent->inum));
366 err = PTR_ERR(inode);
370 ui = ubifs_inode(inode);
371 ubifs_assert(c, inode->i_size == ui->data_len);
372 ubifs_assert(c, ubifs_inode(host)->xattr_size > ui->data_len);
374 mutex_lock(&ui->ui_mutex);
376 /* If @buf is %NULL we are supposed to return the length */
377 if (ui->data_len > size) {
382 memcpy(buf, ui->data, ui->data_len);
387 mutex_unlock(&ui->ui_mutex);
394 static bool xattr_visible(const char *name)
396 /* File encryption related xattrs are for internal use only */
397 if (strcmp(name, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
400 /* Show trusted namespace only for "power" users */
401 if (strncmp(name, XATTR_TRUSTED_PREFIX,
402 XATTR_TRUSTED_PREFIX_LEN) == 0 && !capable(CAP_SYS_ADMIN))
408 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
411 struct inode *host = d_inode(dentry);
412 struct ubifs_info *c = host->i_sb->s_fs_info;
413 struct ubifs_inode *host_ui = ubifs_inode(host);
414 struct ubifs_dent_node *xent, *pxent = NULL;
415 int err, len, written = 0;
416 struct fscrypt_name nm = {0};
418 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
421 len = host_ui->xattr_names + host_ui->xattr_cnt;
424 * We should return the minimum buffer size which will fit a
425 * null-terminated list of all the extended attribute names.
432 lowest_xent_key(c, &key, host->i_ino);
434 xent = ubifs_tnc_next_ent(c, &key, &nm);
440 fname_name(&nm) = xent->name;
441 fname_len(&nm) = le16_to_cpu(xent->nlen);
443 if (xattr_visible(xent->name)) {
444 memcpy(buffer + written, fname_name(&nm), fname_len(&nm) + 1);
445 written += fname_len(&nm) + 1;
450 key_read(c, &xent->key, &key);
454 if (err != -ENOENT) {
455 ubifs_err(c, "cannot find next direntry, error %d", err);
459 ubifs_assert(c, written <= size);
463 static int remove_xattr(struct ubifs_info *c, struct inode *host,
464 struct inode *inode, const struct fscrypt_name *nm)
467 struct ubifs_inode *host_ui = ubifs_inode(host);
468 struct ubifs_inode *ui = ubifs_inode(inode);
469 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
470 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
472 ubifs_assert(c, ui->data_len == inode->i_size);
474 err = ubifs_budget_space(c, &req);
478 mutex_lock(&host_ui->ui_mutex);
479 host->i_ctime = current_time(host);
480 host_ui->xattr_cnt -= 1;
481 host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
482 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
483 host_ui->xattr_names -= fname_len(nm);
485 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
488 mutex_unlock(&host_ui->ui_mutex);
490 ubifs_release_budget(c, &req);
494 host_ui->xattr_cnt += 1;
495 host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
496 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
497 host_ui->xattr_names += fname_len(nm);
498 mutex_unlock(&host_ui->ui_mutex);
499 ubifs_release_budget(c, &req);
500 make_bad_inode(inode);
504 int ubifs_purge_xattrs(struct inode *host)
507 struct ubifs_info *c = host->i_sb->s_fs_info;
508 struct ubifs_dent_node *xent, *pxent = NULL;
510 struct fscrypt_name nm = {0};
513 if (ubifs_inode(host)->xattr_cnt < ubifs_xattr_max_cnt(c))
516 ubifs_warn(c, "inode %lu has too many xattrs, doing a non-atomic deletion",
519 lowest_xent_key(c, &key, host->i_ino);
521 xent = ubifs_tnc_next_ent(c, &key, &nm);
527 fname_name(&nm) = xent->name;
528 fname_len(&nm) = le16_to_cpu(xent->nlen);
530 xino = ubifs_iget(c->vfs_sb, le64_to_cpu(xent->inum));
533 ubifs_err(c, "dead directory entry '%s', error %d",
535 ubifs_ro_mode(c, err);
540 ubifs_assert(c, ubifs_inode(xino)->xattr);
543 err = remove_xattr(c, host, xino, &nm);
547 ubifs_err(c, "cannot remove xattr, error %d", err);
555 key_read(c, &xent->key, &key);
559 if (err != -ENOENT) {
560 ubifs_err(c, "cannot find next direntry, error %d", err);
568 * ubifs_evict_xattr_inode - Evict an xattr inode.
569 * @c: UBIFS file-system description object
570 * @xattr_inum: xattr inode number
572 * When an inode that hosts xattrs is being removed we have to make sure
573 * that cached inodes of the xattrs also get removed from the inode cache
574 * otherwise we'd waste memory. This function looks up an inode from the
575 * inode cache and clears the link counter such that iput() will evict
578 void ubifs_evict_xattr_inode(struct ubifs_info *c, ino_t xattr_inum)
582 inode = ilookup(c->vfs_sb, xattr_inum);
589 static int ubifs_xattr_remove(struct inode *host, const char *name)
592 struct ubifs_info *c = host->i_sb->s_fs_info;
593 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
594 struct ubifs_dent_node *xent;
598 ubifs_assert(c, inode_is_locked(host));
600 if (fname_len(&nm) > UBIFS_MAX_NLEN)
601 return -ENAMETOOLONG;
603 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
607 xent_key_init(c, &key, host->i_ino, &nm);
608 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
615 inode = iget_xattr(c, le64_to_cpu(xent->inum));
617 err = PTR_ERR(inode);
621 ubifs_assert(c, inode->i_nlink == 1);
623 err = remove_xattr(c, host, inode, &nm);
627 /* If @i_nlink is 0, 'iput()' will delete the inode */
635 #ifdef CONFIG_UBIFS_FS_SECURITY
636 static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
639 const struct xattr *xattr;
643 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
644 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
645 strlen(xattr->name) + 1, GFP_NOFS);
650 strcpy(name, XATTR_SECURITY_PREFIX);
651 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
653 * creating a new inode without holding the inode rwsem,
654 * no need to check whether inode is locked.
656 err = ubifs_xattr_set(inode, name, xattr->value,
657 xattr->value_len, 0, false);
666 int ubifs_init_security(struct inode *dentry, struct inode *inode,
667 const struct qstr *qstr)
671 err = security_inode_init_security(inode, dentry, qstr,
674 struct ubifs_info *c = dentry->i_sb->s_fs_info;
675 ubifs_err(c, "cannot initialize security for inode %lu, error %d",
682 static int xattr_get(const struct xattr_handler *handler,
683 struct dentry *dentry, struct inode *inode,
684 const char *name, void *buffer, size_t size)
686 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
687 inode->i_ino, dentry, size);
689 name = xattr_full_name(handler, name);
690 return ubifs_xattr_get(inode, name, buffer, size);
693 static int xattr_set(const struct xattr_handler *handler,
694 struct dentry *dentry, struct inode *inode,
695 const char *name, const void *value,
696 size_t size, int flags)
698 dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
699 name, inode->i_ino, dentry, size);
701 name = xattr_full_name(handler, name);
704 return ubifs_xattr_set(inode, name, value, size, flags, true);
706 return ubifs_xattr_remove(inode, name);
709 static const struct xattr_handler ubifs_user_xattr_handler = {
710 .prefix = XATTR_USER_PREFIX,
715 static const struct xattr_handler ubifs_trusted_xattr_handler = {
716 .prefix = XATTR_TRUSTED_PREFIX,
721 #ifdef CONFIG_UBIFS_FS_SECURITY
722 static const struct xattr_handler ubifs_security_xattr_handler = {
723 .prefix = XATTR_SECURITY_PREFIX,
729 const struct xattr_handler *ubifs_xattr_handlers[] = {
730 &ubifs_user_xattr_handler,
731 &ubifs_trusted_xattr_handler,
732 #ifdef CONFIG_UBIFS_FS_SECURITY
733 &ubifs_security_xattr_handler,