/* * This file is part of UBIFS. * * Copyright (C) 2006-2008 Nokia Corporation. * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published by * the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for * more details. * * You should have received a copy of the GNU General Public License along with * this program; if not, write to the Free Software Foundation, Inc., 51 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA * * Authors: Artem Bityutskiy (Битюцкий Артём) * Adrian Hunter */ /* * This file implements UBIFS extended attributes support. * * Extended attributes are implemented as regular inodes with attached data, * which limits extended attribute size to UBIFS block size (4KiB). Names of * extended attributes are described by extended attribute entries (xentries), * which are almost identical to directory entries, but have different key type. * * In other words, the situation with extended attributes is very similar to * directories. Indeed, any inode (but of course not xattr inodes) may have a * number of associated xentries, just like directory inodes have associated * directory entries. Extended attribute entries store the name of the extended * attribute, the host inode number, and the extended attribute inode number. * Similarly, direntries store the name, the parent and the target inode * numbers. Thus, most of the common UBIFS mechanisms may be re-used for * extended attributes. * * The number of extended attributes is not limited, but there is Linux * limitation on the maximum possible size of the list of all extended * attributes associated with an inode (%XATTR_LIST_MAX), so UBIFS makes sure * the sum of all extended attribute names of the inode does not exceed that * limit. * * Extended attributes are synchronous, which means they are written to the * flash media synchronously and there is no write-back for extended attribute * inodes. The extended attribute values are not stored in compressed form on * the media. * * Since extended attributes are represented by regular inodes, they are cached * in the VFS inode cache. The xentries are cached in the LNC cache (see * tnc.c). * * ACL support is not implemented. */ #include "ubifs.h" #include <linux/fs.h> #include <linux/slab.h> #include <linux/xattr.h> /* * Limit the number of extended attributes per inode so that the total size * (@xattr_size) is guaranteeded to fit in an 'unsigned int'. */ #define MAX_XATTRS_PER_INODE 65535 /* * Extended attribute type constants. * * USER_XATTR: user extended attribute ("user.*") * TRUSTED_XATTR: trusted extended attribute ("trusted.*) * SECURITY_XATTR: security extended attribute ("security.*") */ enum { USER_XATTR, TRUSTED_XATTR, SECURITY_XATTR, }; static const struct inode_operations empty_iops; static const struct file_operations empty_fops; /** * create_xattr - create an extended attribute. * @c: UBIFS file-system description object * @host: host inode * @nm: extended attribute name * @value: extended attribute value * @size: size of extended attribute value * * This is a helper function which creates an extended attribute of name @nm * and value @value for inode @host. The host inode is also updated on flash * because the ctime and extended attribute accounting data changes. This * function returns zero in case of success and a negative error code in case * of failure. */ static int create_xattr(struct ubifs_info *c, struct inode *host, const struct fscrypt_name *nm, const void *value, int size) { int err, names_len; struct inode *inode; struct ubifs_inode *ui, *host_ui = ubifs_inode(host); struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1, .new_ino_d = ALIGN(size, 8), .dirtied_ino = 1, .dirtied_ino_d = ALIGN(host_ui->data_len, 8) }; if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE) { ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more", host->i_ino, host_ui->xattr_cnt); return -ENOSPC; } /* * Linux limits the maximum size of the extended attribute names list * to %XATTR_LIST_MAX. This means we should not allow creating more * extended attributes if the name list becomes larger. This limitation * is artificial for UBIFS, though. */ names_len = host_ui->xattr_names + host_ui->xattr_cnt + fname_len(nm) + 1; if (names_len > XATTR_LIST_MAX) { ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d", host->i_ino, names_len, XATTR_LIST_MAX); return -ENOSPC; } err = ubifs_budget_space(c, &req); if (err) return err; inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO); if (IS_ERR(inode)) { err = PTR_ERR(inode); goto out_budg; } /* Re-define all operations to be "nothing" */ inode->i_mapping->a_ops = &empty_aops; inode->i_op = &empty_iops; inode->i_fop = &empty_fops; inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME; ui = ubifs_inode(inode); ui->xattr = 1; ui->flags |= UBIFS_XATTR_FL; ui->data = kmemdup(value, size, GFP_NOFS); if (!ui->data) { err = -ENOMEM; goto out_free; } inode->i_size = ui->ui_size = size; ui->data_len = size; mutex_lock(&host_ui->ui_mutex); host->i_ctime = current_time(host); host_ui->xattr_cnt += 1; host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm)); host_ui->xattr_size += CALC_XATTR_BYTES(size); host_ui->xattr_names += fname_len(nm); /* * We handle UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT here because we * have to set the UBIFS_CRYPT_FL flag on the host inode. * To avoid multiple updates of the same inode in the same operation, * let's do it here. */ if (strcmp(fname_name(nm), UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0) host_ui->flags |= UBIFS_CRYPT_FL; err = ubifs_jnl_update(c, host, nm, inode, 0, 1); if (err) goto out_cancel; ubifs_set_inode_flags(host); mutex_unlock(&host_ui->ui_mutex); ubifs_release_budget(c, &req); insert_inode_hash(inode); iput(inode); return 0; out_cancel: host_ui->xattr_cnt -= 1; host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm)); host_ui->xattr_size -= CALC_XATTR_BYTES(size); host_ui->xattr_names -= fname_len(nm); host_ui->flags &= ~UBIFS_CRYPT_FL; mutex_unlock(&host_ui->ui_mutex); out_free: make_bad_inode(inode); iput(inode); out_budg: ubifs_release_budget(c, &req); return err; } /** * change_xattr - change an extended attribute. * @c: UBIFS file-system description object * @host: host inode * @inode: extended attribute inode * @value: extended attribute value * @size: size of extended attribute value * * This helper function changes the value of extended attribute @inode with new * data from @value. Returns zero in case of success and a negative error code * in case of failure. */ static int change_xattr(struct ubifs_info *c, struct inode *host, struct inode *inode, const void *value, int size) { int err; struct ubifs_inode *host_ui = ubifs_inode(host); struct ubifs_inode *ui = ubifs_inode(inode); void *buf = NULL; int old_size; struct ubifs_budget_req req = { .dirtied_ino = 2, .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) }; ubifs_assert(c, ui->data_len == inode->i_size); err = ubifs_budget_space(c, &req); if (err) return err; buf = kmemdup(value, size, GFP_NOFS); if (!buf) { err = -ENOMEM; goto out_free; } mutex_lock(&ui->ui_mutex); kfree(ui->data); ui->data = buf; inode->i_size = ui->ui_size = size; old_size = ui->data_len; ui->data_len = size; mutex_unlock(&ui->ui_mutex); mutex_lock(&host_ui->ui_mutex); host->i_ctime = current_time(host); host_ui->xattr_size -= CALC_XATTR_BYTES(old_size); host_ui->xattr_size += CALC_XATTR_BYTES(size); /* * It is important to write the host inode after the xattr inode * because if the host inode gets synchronized (via 'fsync()'), then * the extended attribute inode gets synchronized, because it goes * before the host inode in the write-buffer. */ err = ubifs_jnl_change_xattr(c, inode, host); if (err) goto out_cancel; mutex_unlock(&host_ui->ui_mutex); ubifs_release_budget(c, &req); return 0; out_cancel: host_ui->xattr_size -= CALC_XATTR_BYTES(size); host_ui->xattr_size += CALC_XATTR_BYTES(old_size); mutex_unlock(&host_ui->ui_mutex); make_bad_inode(inode); out_free: ubifs_release_budget(c, &req); return err; } static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum) { struct inode *inode; inode = ubifs_iget(c->vfs_sb, inum); if (IS_ERR(inode)) { ubifs_err(c, "dead extended attribute entry, error %d", (int)PTR_ERR(inode)); return inode; } if (ubifs_inode(inode)->xattr) return inode; ubifs_err(c, "corrupt extended attribute entry"); iput(inode); return ERR_PTR(-EINVAL); } int ubifs_xattr_set(struct inode *host, const char *name, const void *value, size_t size, int flags, bool check_lock) { struct inode *inode; struct ubifs_info *c = host->i_sb->s_fs_info; struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))}; struct ubifs_dent_node *xent; union ubifs_key key; int err; if (check_lock) ubifs_assert(c, inode_is_locked(host)); if (size > UBIFS_MAX_INO_DATA) return -ERANGE; if (fname_len(&nm) > UBIFS_MAX_NLEN) return -ENAMETOOLONG; xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS); if (!xent) return -ENOMEM; /* * The extended attribute entries are stored in LNC, so multiple * look-ups do not involve reading the flash. */ xent_key_init(c, &key, host->i_ino, &nm); err = ubifs_tnc_lookup_nm(c, &key, xent, &nm); if (err) { if (err != -ENOENT) goto out_free; if (flags & XATTR_REPLACE) /* We are asked not to create the xattr */ err = -ENODATA; else err = create_xattr(c, host, &nm, value, size); goto out_free; } if (flags & XATTR_CREATE) { /* We are asked not to replace the xattr */ err = -EEXIST; goto out_free; } inode = iget_xattr(c, le64_to_cpu(xent->inum)); if (IS_ERR(inode)) { err = PTR_ERR(inode); goto out_free; } err = change_xattr(c, host, inode, value, size); iput(inode); out_free: kfree(xent); return err; } ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf, size_t size) { struct inode *inode; struct ubifs_info *c = host->i_sb->s_fs_info; struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))}; struct ubifs_inode *ui; struct ubifs_dent_node *xent; union ubifs_key key; int err; if (fname_len(&nm) > UBIFS_MAX_NLEN) return -ENAMETOOLONG; xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS); if (!xent) return -ENOMEM; xent_key_init(c, &key, host->i_ino, &nm); err = ubifs_tnc_lookup_nm(c, &key, xent, &nm); if (err) { if (err == -ENOENT) err = -ENODATA; goto out_unlock; } inode = iget_xattr(c, le64_to_cpu(xent->inum)); if (IS_ERR(inode)) { err = PTR_ERR(inode); goto out_unlock; } ui = ubifs_inode(inode); ubifs_assert(c, inode->i_size == ui->data_len); ubifs_assert(c, ubifs_inode(host)->xattr_size > ui->data_len); mutex_lock(&ui->ui_mutex); if (buf) { /* If @buf is %NULL we are supposed to return the length */ if (ui->data_len > size) { err = -ERANGE; goto out_iput; } memcpy(buf, ui->data, ui->data_len); } err = ui->data_len; out_iput: mutex_unlock(&ui->ui_mutex); iput(inode); out_unlock: kfree(xent); return err; } static bool xattr_visible(const char *name) { /* File encryption related xattrs are for internal use only */ if (strcmp(name, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0) return false; /* Show trusted namespace only for "power" users */ if (strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) == 0 && !capable(CAP_SYS_ADMIN)) return false; return true; } ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size) { union ubifs_key key; struct inode *host = d_inode(dentry); struct ubifs_info *c = host->i_sb->s_fs_info; struct ubifs_inode *host_ui = ubifs_inode(host); struct ubifs_dent_node *xent, *pxent = NULL; int err, len, written = 0; struct fscrypt_name nm = {0}; dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino, dentry, size); len = host_ui->xattr_names + host_ui->xattr_cnt; if (!buffer) /* * We should return the minimum buffer size which will fit a * null-terminated list of all the extended attribute names. */ return len; if (len > size) return -ERANGE; lowest_xent_key(c, &key, host->i_ino); while (1) { xent = ubifs_tnc_next_ent(c, &key, &nm); if (IS_ERR(xent)) { err = PTR_ERR(xent); break; } fname_name(&nm) = xent->name; fname_len(&nm) = le16_to_cpu(xent->nlen); if (xattr_visible(xent->name)) { memcpy(buffer + written, fname_name(&nm), fname_len(&nm) + 1); written += fname_len(&nm) + 1; } kfree(pxent); pxent = xent; key_read(c, &xent->key, &key); } kfree(pxent); if (err != -ENOENT) { ubifs_err(c, "cannot find next direntry, error %d", err); return err; } ubifs_assert(c, written <= size); return written; } static int remove_xattr(struct ubifs_info *c, struct inode *host, struct inode *inode, const struct fscrypt_name *nm) { int err; struct ubifs_inode *host_ui = ubifs_inode(host); struct ubifs_inode *ui = ubifs_inode(inode); struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1, .dirtied_ino_d = ALIGN(host_ui->data_len, 8) }; ubifs_assert(c, ui->data_len == inode->i_size); err = ubifs_budget_space(c, &req); if (err) return err; mutex_lock(&host_ui->ui_mutex); host->i_ctime = current_time(host); host_ui->xattr_cnt -= 1; host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm)); host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len); host_ui->xattr_names -= fname_len(nm); err = ubifs_jnl_delete_xattr(c, host, inode, nm); if (err) goto out_cancel; mutex_unlock(&host_ui->ui_mutex); ubifs_release_budget(c, &req); return 0; out_cancel: host_ui->xattr_cnt += 1; host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm)); host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len); host_ui->xattr_names += fname_len(nm); mutex_unlock(&host_ui->ui_mutex); ubifs_release_budget(c, &req); make_bad_inode(inode); return err; } /** * ubifs_evict_xattr_inode - Evict an xattr inode. * @c: UBIFS file-system description object * @xattr_inum: xattr inode number * * When an inode that hosts xattrs is being removed we have to make sure * that cached inodes of the xattrs also get removed from the inode cache * otherwise we'd waste memory. This function looks up an inode from the * inode cache and clears the link counter such that iput() will evict * the inode. */ void ubifs_evict_xattr_inode(struct ubifs_info *c, ino_t xattr_inum) { struct inode *inode; inode = ilookup(c->vfs_sb, xattr_inum); if (inode) { clear_nlink(inode); iput(inode); } } static int ubifs_xattr_remove(struct inode *host, const char *name) { struct inode *inode; struct ubifs_info *c = host->i_sb->s_fs_info; struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))}; struct ubifs_dent_node *xent; union ubifs_key key; int err; ubifs_assert(c, inode_is_locked(host)); if (fname_len(&nm) > UBIFS_MAX_NLEN) return -ENAMETOOLONG; xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS); if (!xent) return -ENOMEM; xent_key_init(c, &key, host->i_ino, &nm); err = ubifs_tnc_lookup_nm(c, &key, xent, &nm); if (err) { if (err == -ENOENT) err = -ENODATA; goto out_free; } inode = iget_xattr(c, le64_to_cpu(xent->inum)); if (IS_ERR(inode)) { err = PTR_ERR(inode); goto out_free; } ubifs_assert(c, inode->i_nlink == 1); clear_nlink(inode); err = remove_xattr(c, host, inode, &nm); if (err) set_nlink(inode, 1); /* If @i_nlink is 0, 'iput()' will delete the inode */ iput(inode); out_free: kfree(xent); return err; } #ifdef CONFIG_UBIFS_FS_SECURITY static int init_xattrs(struct inode *inode, const struct xattr *xattr_array, void *fs_info) { const struct xattr *xattr; char *name; int err = 0; for (xattr = xattr_array; xattr->name != NULL; xattr++) { name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(xattr->name) + 1, GFP_NOFS); if (!name) { err = -ENOMEM; break; } strcpy(name, XATTR_SECURITY_PREFIX); strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); /* * creating a new inode without holding the inode rwsem, * no need to check whether inode is locked. */ err = ubifs_xattr_set(inode, name, xattr->value, xattr->value_len, 0, false); kfree(name); if (err < 0) break; } return err; } int ubifs_init_security(struct inode *dentry, struct inode *inode, const struct qstr *qstr) { int err; err = security_inode_init_security(inode, dentry, qstr, &init_xattrs, 0); if (err) { struct ubifs_info *c = dentry->i_sb->s_fs_info; ubifs_err(c, "cannot initialize security for inode %lu, error %d", inode->i_ino, err); } return err; } #endif static int xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, void *buffer, size_t size) { dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name, inode->i_ino, dentry, size); name = xattr_full_name(handler, name); return ubifs_xattr_get(inode, name, buffer, size); } static int xattr_set(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, const void *value, size_t size, int flags) { dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd", name, inode->i_ino, dentry, size); name = xattr_full_name(handler, name); if (value) return ubifs_xattr_set(inode, name, value, size, flags, true); else return ubifs_xattr_remove(inode, name); } static const struct xattr_handler ubifs_user_xattr_handler = { .prefix = XATTR_USER_PREFIX, .get = xattr_get, .set = xattr_set, }; static const struct xattr_handler ubifs_trusted_xattr_handler = { .prefix = XATTR_TRUSTED_PREFIX, .get = xattr_get, .set = xattr_set, }; #ifdef CONFIG_UBIFS_FS_SECURITY static const struct xattr_handler ubifs_security_xattr_handler = { .prefix = XATTR_SECURITY_PREFIX, .get = xattr_get, .set = xattr_set, }; #endif const struct xattr_handler *ubifs_xattr_handlers[] = { &ubifs_user_xattr_handler, &ubifs_trusted_xattr_handler, #ifdef CONFIG_UBIFS_FS_SECURITY &ubifs_security_xattr_handler, #endif NULL };