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7f09410bbc
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
572 lines
16 KiB
C
572 lines
16 KiB
C
/*
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* This file is part of UBIFS.
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*
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* Copyright (C) 2006-2008 Nokia Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Authors: Artem Bityutskiy (Битюцкий Артём)
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* Adrian Hunter
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*/
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/*
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* This file implements UBIFS extended attributes support.
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*
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* Extended attributes are implemented as regular inodes with attached data,
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* which limits extended attribute size to UBIFS block size (4KiB). Names of
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* extended attributes are described by extended attribute entries (xentries),
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* which are almost identical to directory entries, but have different key type.
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*
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* In other words, the situation with extended attributes is very similar to
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* directories. Indeed, any inode (but of course not xattr inodes) may have a
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* number of associated xentries, just like directory inodes have associated
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* directory entries. Extended attribute entries store the name of the extended
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* attribute, the host inode number, and the extended attribute inode number.
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* Similarly, direntries store the name, the parent and the target inode
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* numbers. Thus, most of the common UBIFS mechanisms may be re-used for
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* extended attributes.
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*
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* The number of extended attributes is not limited, but there is Linux
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* limitation on the maximum possible size of the list of all extended
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* attributes associated with an inode (%XATTR_LIST_MAX), so UBIFS makes sure
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* the sum of all extended attribute names of the inode does not exceed that
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* limit.
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*
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* Extended attributes are synchronous, which means they are written to the
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* flash media synchronously and there is no write-back for extended attribute
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* inodes. The extended attribute values are not stored in compressed form on
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* the media.
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*
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* Since extended attributes are represented by regular inodes, they are cached
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* in the VFS inode cache. The xentries are cached in the LNC cache (see
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* tnc.c).
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*
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* ACL support is not implemented.
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*/
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#include "ubifs.h"
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#include <linux/xattr.h>
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#include <linux/posix_acl_xattr.h>
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/*
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* Limit the number of extended attributes per inode so that the total size
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* (@xattr_size) is guaranteeded to fit in an 'unsigned int'.
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*/
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#define MAX_XATTRS_PER_INODE 65535
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/*
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* Extended attribute type constants.
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*
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* USER_XATTR: user extended attribute ("user.*")
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* TRUSTED_XATTR: trusted extended attribute ("trusted.*)
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* SECURITY_XATTR: security extended attribute ("security.*")
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*/
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enum {
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USER_XATTR,
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TRUSTED_XATTR,
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SECURITY_XATTR,
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};
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static const struct inode_operations none_inode_operations;
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static const struct address_space_operations none_address_operations;
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static const struct file_operations none_file_operations;
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/**
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* create_xattr - create an extended attribute.
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* @c: UBIFS file-system description object
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* @host: host inode
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* @nm: extended attribute name
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* @value: extended attribute value
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* @size: size of extended attribute value
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*
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* This is a helper function which creates an extended attribute of name @nm
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* and value @value for inode @host. The host inode is also updated on flash
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* because the ctime and extended attribute accounting data changes. This
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* function returns zero in case of success and a negative error code in case
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* of failure.
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*/
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static int create_xattr(struct ubifs_info *c, struct inode *host,
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const struct qstr *nm, const void *value, int size)
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{
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int err;
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struct inode *inode;
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struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
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struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
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.new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
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.dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
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if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE)
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return -ENOSPC;
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/*
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* Linux limits the maximum size of the extended attribute names list
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* to %XATTR_LIST_MAX. This means we should not allow creating more
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* extended attributes if the name list becomes larger. This limitation
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* is artificial for UBIFS, though.
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*/
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if (host_ui->xattr_names + host_ui->xattr_cnt +
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nm->len + 1 > XATTR_LIST_MAX)
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return -ENOSPC;
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err = ubifs_budget_space(c, &req);
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if (err)
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return err;
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inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
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if (IS_ERR(inode)) {
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err = PTR_ERR(inode);
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goto out_budg;
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}
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/* Re-define all operations to be "nothing" */
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inode->i_mapping->a_ops = &none_address_operations;
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inode->i_op = &none_inode_operations;
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inode->i_fop = &none_file_operations;
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inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME | S_NOQUOTA;
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ui = ubifs_inode(inode);
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ui->xattr = 1;
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ui->flags |= UBIFS_XATTR_FL;
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ui->data = kmalloc(size, GFP_NOFS);
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if (!ui->data) {
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err = -ENOMEM;
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goto out_free;
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}
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memcpy(ui->data, value, size);
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inode->i_size = ui->ui_size = size;
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ui->data_len = size;
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mutex_lock(&host_ui->ui_mutex);
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host->i_ctime = ubifs_current_time(host);
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host_ui->xattr_cnt += 1;
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host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
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host_ui->xattr_size += CALC_XATTR_BYTES(size);
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host_ui->xattr_names += nm->len;
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err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
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if (err)
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goto out_cancel;
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mutex_unlock(&host_ui->ui_mutex);
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ubifs_release_budget(c, &req);
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insert_inode_hash(inode);
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iput(inode);
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return 0;
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out_cancel:
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host_ui->xattr_cnt -= 1;
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host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
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host_ui->xattr_size -= CALC_XATTR_BYTES(size);
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mutex_unlock(&host_ui->ui_mutex);
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out_free:
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make_bad_inode(inode);
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iput(inode);
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out_budg:
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ubifs_release_budget(c, &req);
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return err;
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}
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/**
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* change_xattr - change an extended attribute.
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* @c: UBIFS file-system description object
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* @host: host inode
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* @inode: extended attribute inode
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* @value: extended attribute value
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* @size: size of extended attribute value
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*
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* This helper function changes the value of extended attribute @inode with new
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* data from @value. Returns zero in case of success and a negative error code
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* in case of failure.
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*/
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static int change_xattr(struct ubifs_info *c, struct inode *host,
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struct inode *inode, const void *value, int size)
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{
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int err;
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struct ubifs_inode *host_ui = ubifs_inode(host);
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struct ubifs_inode *ui = ubifs_inode(inode);
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struct ubifs_budget_req req = { .dirtied_ino = 2,
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.dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
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ubifs_assert(ui->data_len == inode->i_size);
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err = ubifs_budget_space(c, &req);
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if (err)
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return err;
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kfree(ui->data);
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ui->data = kmalloc(size, GFP_NOFS);
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if (!ui->data) {
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err = -ENOMEM;
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goto out_free;
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}
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memcpy(ui->data, value, size);
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inode->i_size = ui->ui_size = size;
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ui->data_len = size;
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mutex_lock(&host_ui->ui_mutex);
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host->i_ctime = ubifs_current_time(host);
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host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
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host_ui->xattr_size += CALC_XATTR_BYTES(size);
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/*
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* It is important to write the host inode after the xattr inode
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* because if the host inode gets synchronized (via 'fsync()'), then
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* the extended attribute inode gets synchronized, because it goes
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* before the host inode in the write-buffer.
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*/
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err = ubifs_jnl_change_xattr(c, inode, host);
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if (err)
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goto out_cancel;
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mutex_unlock(&host_ui->ui_mutex);
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ubifs_release_budget(c, &req);
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return 0;
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out_cancel:
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host_ui->xattr_size -= CALC_XATTR_BYTES(size);
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host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
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mutex_unlock(&host_ui->ui_mutex);
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make_bad_inode(inode);
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out_free:
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ubifs_release_budget(c, &req);
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return err;
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}
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/**
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* check_namespace - check extended attribute name-space.
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* @nm: extended attribute name
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*
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* This function makes sure the extended attribute name belongs to one of the
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* supported extended attribute name-spaces. Returns name-space index in case
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* of success and a negative error code in case of failure.
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*/
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static int check_namespace(const struct qstr *nm)
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{
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int type;
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if (nm->len > UBIFS_MAX_NLEN)
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return -ENAMETOOLONG;
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if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
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XATTR_TRUSTED_PREFIX_LEN)) {
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if (nm->name[sizeof(XATTR_TRUSTED_PREFIX) - 1] == '\0')
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return -EINVAL;
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type = TRUSTED_XATTR;
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} else if (!strncmp(nm->name, XATTR_USER_PREFIX,
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XATTR_USER_PREFIX_LEN)) {
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if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
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return -EINVAL;
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type = USER_XATTR;
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} else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
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XATTR_SECURITY_PREFIX_LEN)) {
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if (nm->name[sizeof(XATTR_SECURITY_PREFIX) - 1] == '\0')
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return -EINVAL;
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type = SECURITY_XATTR;
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} else
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return -EOPNOTSUPP;
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return type;
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}
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static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
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{
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struct inode *inode;
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inode = ubifs_iget(c->vfs_sb, inum);
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if (IS_ERR(inode)) {
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ubifs_err("dead extended attribute entry, error %d",
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(int)PTR_ERR(inode));
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return inode;
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}
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if (ubifs_inode(inode)->xattr)
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return inode;
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ubifs_err("corrupt extended attribute entry");
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iput(inode);
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return ERR_PTR(-EINVAL);
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}
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int ubifs_setxattr(struct dentry *dentry, const char *name,
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const void *value, size_t size, int flags)
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{
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struct inode *inode, *host = dentry->d_inode;
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struct ubifs_info *c = host->i_sb->s_fs_info;
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struct qstr nm = { .name = name, .len = strlen(name) };
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struct ubifs_dent_node *xent;
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union ubifs_key key;
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int err, type;
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dbg_gen("xattr '%s', host ino %lu ('%.*s'), size %zd", name,
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host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
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ubifs_assert(mutex_is_locked(&host->i_mutex));
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if (size > UBIFS_MAX_INO_DATA)
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return -ERANGE;
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type = check_namespace(&nm);
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if (type < 0)
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return type;
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xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
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if (!xent)
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return -ENOMEM;
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/*
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* The extended attribute entries are stored in LNC, so multiple
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* look-ups do not involve reading the flash.
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*/
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xent_key_init(c, &key, host->i_ino, &nm);
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err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
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if (err) {
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if (err != -ENOENT)
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goto out_free;
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if (flags & XATTR_REPLACE)
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/* We are asked not to create the xattr */
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err = -ENODATA;
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else
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err = create_xattr(c, host, &nm, value, size);
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goto out_free;
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}
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if (flags & XATTR_CREATE) {
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/* We are asked not to replace the xattr */
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err = -EEXIST;
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goto out_free;
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}
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inode = iget_xattr(c, le64_to_cpu(xent->inum));
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if (IS_ERR(inode)) {
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err = PTR_ERR(inode);
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goto out_free;
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}
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err = change_xattr(c, host, inode, value, size);
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iput(inode);
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out_free:
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kfree(xent);
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return err;
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}
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ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
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size_t size)
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{
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struct inode *inode, *host = dentry->d_inode;
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struct ubifs_info *c = host->i_sb->s_fs_info;
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struct qstr nm = { .name = name, .len = strlen(name) };
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struct ubifs_inode *ui;
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struct ubifs_dent_node *xent;
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union ubifs_key key;
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int err;
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dbg_gen("xattr '%s', ino %lu ('%.*s'), buf size %zd", name,
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host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
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err = check_namespace(&nm);
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if (err < 0)
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return err;
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xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
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if (!xent)
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return -ENOMEM;
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xent_key_init(c, &key, host->i_ino, &nm);
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err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
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if (err) {
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if (err == -ENOENT)
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err = -ENODATA;
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goto out_unlock;
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}
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inode = iget_xattr(c, le64_to_cpu(xent->inum));
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if (IS_ERR(inode)) {
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err = PTR_ERR(inode);
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goto out_unlock;
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}
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ui = ubifs_inode(inode);
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ubifs_assert(inode->i_size == ui->data_len);
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ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
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if (buf) {
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/* If @buf is %NULL we are supposed to return the length */
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if (ui->data_len > size) {
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dbg_err("buffer size %zd, xattr len %d",
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size, ui->data_len);
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err = -ERANGE;
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goto out_iput;
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}
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memcpy(buf, ui->data, ui->data_len);
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}
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err = ui->data_len;
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out_iput:
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iput(inode);
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out_unlock:
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kfree(xent);
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return err;
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}
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ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
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{
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union ubifs_key key;
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struct inode *host = dentry->d_inode;
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struct ubifs_info *c = host->i_sb->s_fs_info;
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struct ubifs_inode *host_ui = ubifs_inode(host);
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struct ubifs_dent_node *xent, *pxent = NULL;
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int err, len, written = 0;
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struct qstr nm = { .name = NULL };
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dbg_gen("ino %lu ('%.*s'), buffer size %zd", host->i_ino,
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dentry->d_name.len, dentry->d_name.name, size);
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len = host_ui->xattr_names + host_ui->xattr_cnt;
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if (!buffer)
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/*
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* We should return the minimum buffer size which will fit a
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* null-terminated list of all the extended attribute names.
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*/
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return len;
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if (len > size)
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return -ERANGE;
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lowest_xent_key(c, &key, host->i_ino);
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while (1) {
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int type;
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xent = ubifs_tnc_next_ent(c, &key, &nm);
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if (IS_ERR(xent)) {
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err = PTR_ERR(xent);
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break;
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}
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nm.name = xent->name;
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nm.len = le16_to_cpu(xent->nlen);
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type = check_namespace(&nm);
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if (unlikely(type < 0)) {
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err = type;
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break;
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}
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/* Show trusted namespace only for "power" users */
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if (type != TRUSTED_XATTR || capable(CAP_SYS_ADMIN)) {
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memcpy(buffer + written, nm.name, nm.len + 1);
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written += nm.len + 1;
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}
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kfree(pxent);
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pxent = xent;
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key_read(c, &xent->key, &key);
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}
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kfree(pxent);
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if (err != -ENOENT) {
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ubifs_err("cannot find next direntry, error %d", err);
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return err;
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}
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ubifs_assert(written <= size);
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return written;
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}
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static int remove_xattr(struct ubifs_info *c, struct inode *host,
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struct inode *inode, const struct qstr *nm)
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{
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int err;
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struct ubifs_inode *host_ui = ubifs_inode(host);
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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(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 = ubifs_current_time(host);
|
|
host_ui->xattr_cnt -= 1;
|
|
host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
|
|
host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
|
|
host_ui->xattr_names -= nm->len;
|
|
|
|
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(nm->len);
|
|
host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
|
|
mutex_unlock(&host_ui->ui_mutex);
|
|
ubifs_release_budget(c, &req);
|
|
make_bad_inode(inode);
|
|
return err;
|
|
}
|
|
|
|
int ubifs_removexattr(struct dentry *dentry, const char *name)
|
|
{
|
|
struct inode *inode, *host = dentry->d_inode;
|
|
struct ubifs_info *c = host->i_sb->s_fs_info;
|
|
struct qstr nm = { .name = name, .len = strlen(name) };
|
|
struct ubifs_dent_node *xent;
|
|
union ubifs_key key;
|
|
int err;
|
|
|
|
dbg_gen("xattr '%s', ino %lu ('%.*s')", name,
|
|
host->i_ino, dentry->d_name.len, dentry->d_name.name);
|
|
ubifs_assert(mutex_is_locked(&host->i_mutex));
|
|
|
|
err = check_namespace(&nm);
|
|
if (err < 0)
|
|
return err;
|
|
|
|
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(inode->i_nlink == 1);
|
|
inode->i_nlink = 0;
|
|
err = remove_xattr(c, host, inode, &nm);
|
|
if (err)
|
|
inode->i_nlink = 1;
|
|
|
|
/* If @i_nlink is 0, 'iput()' will delete the inode */
|
|
iput(inode);
|
|
|
|
out_free:
|
|
kfree(xent);
|
|
return err;
|
|
}
|