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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * This file is part of UBIFS.4 *5 * Copyright (C) 2006-2008 Nokia Corporation.6 *7 * Authors: Artem Bityutskiy (Битюцкий Артём)8 * Adrian Hunter9 */10 11/*12 * This file implements UBIFS extended attributes support.13 *14 * Extended attributes are implemented as regular inodes with attached data,15 * which limits extended attribute size to UBIFS block size (4KiB). Names of16 * extended attributes are described by extended attribute entries (xentries),17 * which are almost identical to directory entries, but have different key type.18 *19 * In other words, the situation with extended attributes is very similar to20 * directories. Indeed, any inode (but of course not xattr inodes) may have a21 * number of associated xentries, just like directory inodes have associated22 * directory entries. Extended attribute entries store the name of the extended23 * attribute, the host inode number, and the extended attribute inode number.24 * Similarly, direntries store the name, the parent and the target inode25 * numbers. Thus, most of the common UBIFS mechanisms may be re-used for26 * extended attributes.27 *28 * The number of extended attributes is not limited, but there is Linux29 * limitation on the maximum possible size of the list of all extended30 * attributes associated with an inode (%XATTR_LIST_MAX), so UBIFS makes sure31 * the sum of all extended attribute names of the inode does not exceed that32 * limit.33 *34 * Extended attributes are synchronous, which means they are written to the35 * flash media synchronously and there is no write-back for extended attribute36 * inodes. The extended attribute values are not stored in compressed form on37 * the media.38 *39 * Since extended attributes are represented by regular inodes, they are cached40 * in the VFS inode cache. The xentries are cached in the LNC cache (see41 * tnc.c).42 *43 * ACL support is not implemented.44 */45 46#include "ubifs.h"47#include <linux/fs.h>48#include <linux/slab.h>49#include <linux/xattr.h>50 51/*52 * Extended attribute type constants.53 *54 * USER_XATTR: user extended attribute ("user.*")55 * TRUSTED_XATTR: trusted extended attribute ("trusted.*)56 * SECURITY_XATTR: security extended attribute ("security.*")57 */58enum {59 USER_XATTR,60 TRUSTED_XATTR,61 SECURITY_XATTR,62};63 64static const struct inode_operations empty_iops;65static const struct file_operations empty_fops;66 67/**68 * create_xattr - create an extended attribute.69 * @c: UBIFS file-system description object70 * @host: host inode71 * @nm: extended attribute name72 * @value: extended attribute value73 * @size: size of extended attribute value74 *75 * This is a helper function which creates an extended attribute of name @nm76 * and value @value for inode @host. The host inode is also updated on flash77 * because the ctime and extended attribute accounting data changes. This78 * function returns zero in case of success and a negative error code in case79 * of failure.80 */81static int create_xattr(struct ubifs_info *c, struct inode *host,82 const struct fscrypt_name *nm, const void *value, int size)83{84 int err, names_len;85 struct inode *inode;86 struct ubifs_inode *ui, *host_ui = ubifs_inode(host);87 struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,88 .new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,89 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };90 91 if (host_ui->xattr_cnt >= ubifs_xattr_max_cnt(c)) {92 ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",93 host->i_ino, host_ui->xattr_cnt);94 return -ENOSPC;95 }96 /*97 * Linux limits the maximum size of the extended attribute names list98 * to %XATTR_LIST_MAX. This means we should not allow creating more99 * extended attributes if the name list becomes larger. This limitation100 * is artificial for UBIFS, though.101 */102 names_len = host_ui->xattr_names + host_ui->xattr_cnt + fname_len(nm) + 1;103 if (names_len > XATTR_LIST_MAX) {104 ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",105 host->i_ino, names_len, XATTR_LIST_MAX);106 return -ENOSPC;107 }108 109 err = ubifs_budget_space(c, &req);110 if (err)111 return err;112 113 inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO, true);114 if (IS_ERR(inode)) {115 err = PTR_ERR(inode);116 goto out_budg;117 }118 119 /* Re-define all operations to be "nothing" */120 inode->i_mapping->a_ops = &empty_aops;121 inode->i_op = &empty_iops;122 inode->i_fop = &empty_fops;123 124 inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME;125 ui = ubifs_inode(inode);126 ui->xattr = 1;127 ui->flags |= UBIFS_XATTR_FL;128 ui->data = kmemdup(value, size, GFP_NOFS);129 if (!ui->data) {130 err = -ENOMEM;131 goto out_free;132 }133 inode->i_size = ui->ui_size = size;134 ui->data_len = size;135 136 mutex_lock(&host_ui->ui_mutex);137 inode_set_ctime_current(host);138 host_ui->xattr_cnt += 1;139 host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));140 host_ui->xattr_size += CALC_XATTR_BYTES(size);141 host_ui->xattr_names += fname_len(nm);142 143 /*144 * We handle UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT here because we145 * have to set the UBIFS_CRYPT_FL flag on the host inode.146 * To avoid multiple updates of the same inode in the same operation,147 * let's do it here.148 */149 if (strcmp(fname_name(nm), UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)150 host_ui->flags |= UBIFS_CRYPT_FL;151 152 err = ubifs_jnl_update(c, host, nm, inode, 0, 1, 0);153 if (err)154 goto out_cancel;155 ubifs_set_inode_flags(host);156 mutex_unlock(&host_ui->ui_mutex);157 158 ubifs_release_budget(c, &req);159 insert_inode_hash(inode);160 iput(inode);161 return 0;162 163out_cancel:164 host_ui->xattr_cnt -= 1;165 host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));166 host_ui->xattr_size -= CALC_XATTR_BYTES(size);167 host_ui->xattr_names -= fname_len(nm);168 host_ui->flags &= ~UBIFS_CRYPT_FL;169 mutex_unlock(&host_ui->ui_mutex);170out_free:171 make_bad_inode(inode);172 iput(inode);173out_budg:174 ubifs_release_budget(c, &req);175 return err;176}177 178/**179 * change_xattr - change an extended attribute.180 * @c: UBIFS file-system description object181 * @host: host inode182 * @inode: extended attribute inode183 * @value: extended attribute value184 * @size: size of extended attribute value185 *186 * This helper function changes the value of extended attribute @inode with new187 * data from @value. Returns zero in case of success and a negative error code188 * in case of failure.189 */190static int change_xattr(struct ubifs_info *c, struct inode *host,191 struct inode *inode, const void *value, int size)192{193 int err;194 struct ubifs_inode *host_ui = ubifs_inode(host);195 struct ubifs_inode *ui = ubifs_inode(inode);196 void *buf = NULL;197 int old_size;198 struct ubifs_budget_req req = { .dirtied_ino = 2,199 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };200 201 ubifs_assert(c, ui->data_len == inode->i_size);202 err = ubifs_budget_space(c, &req);203 if (err)204 return err;205 206 buf = kmemdup(value, size, GFP_NOFS);207 if (!buf) {208 err = -ENOMEM;209 goto out_free;210 }211 kfree(ui->data);212 ui->data = buf;213 inode->i_size = ui->ui_size = size;214 old_size = ui->data_len;215 ui->data_len = size;216 217 mutex_lock(&host_ui->ui_mutex);218 inode_set_ctime_current(host);219 host_ui->xattr_size -= CALC_XATTR_BYTES(old_size);220 host_ui->xattr_size += CALC_XATTR_BYTES(size);221 222 /*223 * It is important to write the host inode after the xattr inode224 * because if the host inode gets synchronized (via 'fsync()'), then225 * the extended attribute inode gets synchronized, because it goes226 * before the host inode in the write-buffer.227 */228 err = ubifs_jnl_change_xattr(c, inode, host);229 if (err)230 goto out_cancel;231 mutex_unlock(&host_ui->ui_mutex);232 233 ubifs_release_budget(c, &req);234 return 0;235 236out_cancel:237 host_ui->xattr_size -= CALC_XATTR_BYTES(size);238 host_ui->xattr_size += CALC_XATTR_BYTES(old_size);239 mutex_unlock(&host_ui->ui_mutex);240 make_bad_inode(inode);241out_free:242 ubifs_release_budget(c, &req);243 return err;244}245 246static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)247{248 struct inode *inode;249 250 inode = ubifs_iget(c->vfs_sb, inum);251 if (IS_ERR(inode)) {252 ubifs_err(c, "dead extended attribute entry, error %d",253 (int)PTR_ERR(inode));254 return inode;255 }256 if (ubifs_inode(inode)->xattr)257 return inode;258 ubifs_err(c, "corrupt extended attribute entry");259 iput(inode);260 return ERR_PTR(-EINVAL);261}262 263int ubifs_xattr_set(struct inode *host, const char *name, const void *value,264 size_t size, int flags, bool check_lock)265{266 struct inode *inode;267 struct ubifs_info *c = host->i_sb->s_fs_info;268 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};269 struct ubifs_dent_node *xent;270 union ubifs_key key;271 int err;272 273 if (check_lock)274 ubifs_assert(c, inode_is_locked(host));275 276 if (size > UBIFS_MAX_INO_DATA)277 return -ERANGE;278 279 if (fname_len(&nm) > UBIFS_MAX_NLEN)280 return -ENAMETOOLONG;281 282 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);283 if (!xent)284 return -ENOMEM;285 286 down_write(&ubifs_inode(host)->xattr_sem);287 /*288 * The extended attribute entries are stored in LNC, so multiple289 * look-ups do not involve reading the flash.290 */291 xent_key_init(c, &key, host->i_ino, &nm);292 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);293 if (err) {294 if (err != -ENOENT)295 goto out_free;296 297 if (flags & XATTR_REPLACE)298 /* We are asked not to create the xattr */299 err = -ENODATA;300 else301 err = create_xattr(c, host, &nm, value, size);302 goto out_free;303 }304 305 if (flags & XATTR_CREATE) {306 /* We are asked not to replace the xattr */307 err = -EEXIST;308 goto out_free;309 }310 311 inode = iget_xattr(c, le64_to_cpu(xent->inum));312 if (IS_ERR(inode)) {313 err = PTR_ERR(inode);314 goto out_free;315 }316 317 err = change_xattr(c, host, inode, value, size);318 iput(inode);319 320out_free:321 up_write(&ubifs_inode(host)->xattr_sem);322 kfree(xent);323 return err;324}325 326ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf,327 size_t size)328{329 struct inode *inode;330 struct ubifs_info *c = host->i_sb->s_fs_info;331 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};332 struct ubifs_inode *ui;333 struct ubifs_dent_node *xent;334 union ubifs_key key;335 int err;336 337 if (fname_len(&nm) > UBIFS_MAX_NLEN)338 return -ENAMETOOLONG;339 340 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);341 if (!xent)342 return -ENOMEM;343 344 down_read(&ubifs_inode(host)->xattr_sem);345 xent_key_init(c, &key, host->i_ino, &nm);346 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);347 if (err) {348 if (err == -ENOENT)349 err = -ENODATA;350 goto out_cleanup;351 }352 353 inode = iget_xattr(c, le64_to_cpu(xent->inum));354 if (IS_ERR(inode)) {355 err = PTR_ERR(inode);356 goto out_cleanup;357 }358 359 ui = ubifs_inode(inode);360 ubifs_assert(c, inode->i_size == ui->data_len);361 ubifs_assert(c, ubifs_inode(host)->xattr_size > ui->data_len);362 363 if (buf) {364 /* If @buf is %NULL we are supposed to return the length */365 if (ui->data_len > size) {366 err = -ERANGE;367 goto out_iput;368 }369 370 memcpy(buf, ui->data, ui->data_len);371 }372 err = ui->data_len;373 374out_iput:375 iput(inode);376out_cleanup:377 up_read(&ubifs_inode(host)->xattr_sem);378 kfree(xent);379 return err;380}381 382static bool xattr_visible(const char *name)383{384 /* File encryption related xattrs are for internal use only */385 if (strcmp(name, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)386 return false;387 388 /* Show trusted namespace only for "power" users */389 if (strncmp(name, XATTR_TRUSTED_PREFIX,390 XATTR_TRUSTED_PREFIX_LEN) == 0 && !capable(CAP_SYS_ADMIN))391 return false;392 393 return true;394}395 396ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)397{398 union ubifs_key key;399 struct inode *host = d_inode(dentry);400 struct ubifs_info *c = host->i_sb->s_fs_info;401 struct ubifs_inode *host_ui = ubifs_inode(host);402 struct ubifs_dent_node *xent, *pxent = NULL;403 int err, len, written = 0;404 struct fscrypt_name nm = {0};405 406 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,407 dentry, size);408 409 down_read(&host_ui->xattr_sem);410 len = host_ui->xattr_names + host_ui->xattr_cnt;411 if (!buffer) {412 /*413 * We should return the minimum buffer size which will fit a414 * null-terminated list of all the extended attribute names.415 */416 err = len;417 goto out_err;418 }419 420 if (len > size) {421 err = -ERANGE;422 goto out_err;423 }424 425 lowest_xent_key(c, &key, host->i_ino);426 while (1) {427 xent = ubifs_tnc_next_ent(c, &key, &nm);428 if (IS_ERR(xent)) {429 err = PTR_ERR(xent);430 break;431 }432 433 fname_name(&nm) = xent->name;434 fname_len(&nm) = le16_to_cpu(xent->nlen);435 436 if (xattr_visible(xent->name)) {437 memcpy(buffer + written, fname_name(&nm), fname_len(&nm) + 1);438 written += fname_len(&nm) + 1;439 }440 441 kfree(pxent);442 pxent = xent;443 key_read(c, &xent->key, &key);444 }445 kfree(pxent);446 up_read(&host_ui->xattr_sem);447 448 if (err != -ENOENT) {449 ubifs_err(c, "cannot find next direntry, error %d", err);450 return err;451 }452 453 ubifs_assert(c, written <= size);454 return written;455 456out_err:457 up_read(&host_ui->xattr_sem);458 return err;459}460 461static int remove_xattr(struct ubifs_info *c, struct inode *host,462 struct inode *inode, const struct fscrypt_name *nm)463{464 int err;465 struct ubifs_inode *host_ui = ubifs_inode(host);466 struct ubifs_inode *ui = ubifs_inode(inode);467 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,468 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };469 470 ubifs_assert(c, ui->data_len == inode->i_size);471 472 err = ubifs_budget_space(c, &req);473 if (err)474 return err;475 476 mutex_lock(&host_ui->ui_mutex);477 inode_set_ctime_current(host);478 host_ui->xattr_cnt -= 1;479 host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));480 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);481 host_ui->xattr_names -= fname_len(nm);482 483 err = ubifs_jnl_delete_xattr(c, host, inode, nm);484 if (err)485 goto out_cancel;486 mutex_unlock(&host_ui->ui_mutex);487 488 ubifs_release_budget(c, &req);489 return 0;490 491out_cancel:492 host_ui->xattr_cnt += 1;493 host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));494 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);495 host_ui->xattr_names += fname_len(nm);496 mutex_unlock(&host_ui->ui_mutex);497 ubifs_release_budget(c, &req);498 make_bad_inode(inode);499 return err;500}501 502int ubifs_purge_xattrs(struct inode *host)503{504 union ubifs_key key;505 struct ubifs_info *c = host->i_sb->s_fs_info;506 struct ubifs_dent_node *xent, *pxent = NULL;507 struct inode *xino;508 struct fscrypt_name nm = {0};509 int err;510 511 if (ubifs_inode(host)->xattr_cnt <= ubifs_xattr_max_cnt(c))512 return 0;513 514 ubifs_warn(c, "inode %lu has too many xattrs, doing a non-atomic deletion",515 host->i_ino);516 517 down_write(&ubifs_inode(host)->xattr_sem);518 lowest_xent_key(c, &key, host->i_ino);519 while (1) {520 xent = ubifs_tnc_next_ent(c, &key, &nm);521 if (IS_ERR(xent)) {522 err = PTR_ERR(xent);523 break;524 }525 526 fname_name(&nm) = xent->name;527 fname_len(&nm) = le16_to_cpu(xent->nlen);528 529 xino = ubifs_iget(c->vfs_sb, le64_to_cpu(xent->inum));530 if (IS_ERR(xino)) {531 err = PTR_ERR(xino);532 ubifs_err(c, "dead directory entry '%s', error %d",533 xent->name, err);534 ubifs_ro_mode(c, err);535 kfree(pxent);536 kfree(xent);537 goto out_err;538 }539 540 ubifs_assert(c, ubifs_inode(xino)->xattr);541 542 clear_nlink(xino);543 err = remove_xattr(c, host, xino, &nm);544 if (err) {545 kfree(pxent);546 kfree(xent);547 iput(xino);548 ubifs_err(c, "cannot remove xattr, error %d", err);549 goto out_err;550 }551 552 iput(xino);553 554 kfree(pxent);555 pxent = xent;556 key_read(c, &xent->key, &key);557 }558 kfree(pxent);559 up_write(&ubifs_inode(host)->xattr_sem);560 561 if (err != -ENOENT) {562 ubifs_err(c, "cannot find next direntry, error %d", err);563 return err;564 }565 566 return 0;567 568out_err:569 up_write(&ubifs_inode(host)->xattr_sem);570 return err;571}572 573/**574 * ubifs_evict_xattr_inode - Evict an xattr inode.575 * @c: UBIFS file-system description object576 * @xattr_inum: xattr inode number577 *578 * When an inode that hosts xattrs is being removed we have to make sure579 * that cached inodes of the xattrs also get removed from the inode cache580 * otherwise we'd waste memory. This function looks up an inode from the581 * inode cache and clears the link counter such that iput() will evict582 * the inode.583 */584void ubifs_evict_xattr_inode(struct ubifs_info *c, ino_t xattr_inum)585{586 struct inode *inode;587 588 inode = ilookup(c->vfs_sb, xattr_inum);589 if (inode) {590 clear_nlink(inode);591 iput(inode);592 }593}594 595static int ubifs_xattr_remove(struct inode *host, const char *name)596{597 struct inode *inode;598 struct ubifs_info *c = host->i_sb->s_fs_info;599 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};600 struct ubifs_dent_node *xent;601 union ubifs_key key;602 int err;603 604 ubifs_assert(c, inode_is_locked(host));605 606 if (fname_len(&nm) > UBIFS_MAX_NLEN)607 return -ENAMETOOLONG;608 609 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);610 if (!xent)611 return -ENOMEM;612 613 down_write(&ubifs_inode(host)->xattr_sem);614 xent_key_init(c, &key, host->i_ino, &nm);615 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);616 if (err) {617 if (err == -ENOENT)618 err = -ENODATA;619 goto out_free;620 }621 622 inode = iget_xattr(c, le64_to_cpu(xent->inum));623 if (IS_ERR(inode)) {624 err = PTR_ERR(inode);625 goto out_free;626 }627 628 ubifs_assert(c, inode->i_nlink == 1);629 clear_nlink(inode);630 err = remove_xattr(c, host, inode, &nm);631 if (err)632 set_nlink(inode, 1);633 634 /* If @i_nlink is 0, 'iput()' will delete the inode */635 iput(inode);636 637out_free:638 up_write(&ubifs_inode(host)->xattr_sem);639 kfree(xent);640 return err;641}642 643#ifdef CONFIG_UBIFS_FS_SECURITY644static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,645 void *fs_info)646{647 const struct xattr *xattr;648 char *name;649 int err = 0;650 651 for (xattr = xattr_array; xattr->name != NULL; xattr++) {652 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +653 strlen(xattr->name) + 1, GFP_NOFS);654 if (!name) {655 err = -ENOMEM;656 break;657 }658 strcpy(name, XATTR_SECURITY_PREFIX);659 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);660 /*661 * creating a new inode without holding the inode rwsem,662 * no need to check whether inode is locked.663 */664 err = ubifs_xattr_set(inode, name, xattr->value,665 xattr->value_len, 0, false);666 kfree(name);667 if (err < 0)668 break;669 }670 671 return err;672}673 674int ubifs_init_security(struct inode *dentry, struct inode *inode,675 const struct qstr *qstr)676{677 int err;678 679 err = security_inode_init_security(inode, dentry, qstr,680 &init_xattrs, NULL);681 if (err) {682 struct ubifs_info *c = dentry->i_sb->s_fs_info;683 ubifs_err(c, "cannot initialize security for inode %lu, error %d",684 inode->i_ino, err);685 }686 return err;687}688#endif689 690static int xattr_get(const struct xattr_handler *handler,691 struct dentry *dentry, struct inode *inode,692 const char *name, void *buffer, size_t size)693{694 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,695 inode->i_ino, dentry, size);696 697 name = xattr_full_name(handler, name);698 return ubifs_xattr_get(inode, name, buffer, size);699}700 701static int xattr_set(const struct xattr_handler *handler,702 struct mnt_idmap *idmap,703 struct dentry *dentry, struct inode *inode,704 const char *name, const void *value,705 size_t size, int flags)706{707 dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",708 name, inode->i_ino, dentry, size);709 710 name = xattr_full_name(handler, name);711 712 if (value)713 return ubifs_xattr_set(inode, name, value, size, flags, true);714 else715 return ubifs_xattr_remove(inode, name);716}717 718static const struct xattr_handler ubifs_user_xattr_handler = {719 .prefix = XATTR_USER_PREFIX,720 .get = xattr_get,721 .set = xattr_set,722};723 724static const struct xattr_handler ubifs_trusted_xattr_handler = {725 .prefix = XATTR_TRUSTED_PREFIX,726 .get = xattr_get,727 .set = xattr_set,728};729 730#ifdef CONFIG_UBIFS_FS_SECURITY731static const struct xattr_handler ubifs_security_xattr_handler = {732 .prefix = XATTR_SECURITY_PREFIX,733 .get = xattr_get,734 .set = xattr_set,735};736#endif737 738const struct xattr_handler * const ubifs_xattr_handlers[] = {739 &ubifs_user_xattr_handler,740 &ubifs_trusted_xattr_handler,741#ifdef CONFIG_UBIFS_FS_SECURITY742 &ubifs_security_xattr_handler,743#endif744 NULL745};746