103 lines
2.9 KiB
C
103 lines
2.9 KiB
C
|
/*
|
||
|
|
* Squashfs - a compressed read only filesystem for Linux
|
||
|
|
*
|
||
|
|
* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
|
||
|
|
* Phillip Lougher <phillip@squashfs.org.uk>
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU General Public License
|
||
|
|
* as published by the Free Software Foundation; either version 2,
|
||
|
|
* or (at your option) any later version.
|
||
|
|
*
|
||
|
|
* 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
||
|
|
*
|
||
|
|
* id.c
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
* This file implements code to handle uids and gids.
|
||
|
|
*
|
||
|
|
* For space efficiency regular files store uid and gid indexes, which are
|
||
|
|
* converted to 32-bit uids/gids using an id look up table. This table is
|
||
|
|
* stored compressed into metadata blocks. A second index table is used to
|
||
|
|
* locate these. This second index table for speed of access (and because it
|
||
|
|
* is small) is read at mount time and cached in memory.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/fs.h>
|
||
|
|
#include <linux/vfs.h>
|
||
|
|
#include <linux/slab.h>
|
||
|
|
|
||
|
|
#include "squashfs_fs.h"
|
||
|
|
#include "squashfs_fs_sb.h"
|
||
|
|
#include "squashfs.h"
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Map uid/gid index into real 32-bit uid/gid using the id look up table
|
||
|
|
*/
|
||
|
|
int squashfs_get_id(struct super_block *sb, unsigned int index,
|
||
|
|
unsigned int *id)
|
||
|
|
{
|
||
|
|
struct squashfs_sb_info *msblk = sb->s_fs_info;
|
||
|
|
int block = SQUASHFS_ID_BLOCK(index);
|
||
|
|
int offset = SQUASHFS_ID_BLOCK_OFFSET(index);
|
||
|
|
u64 start_block = le64_to_cpu(msblk->id_table[block]);
|
||
|
|
__le32 disk_id;
|
||
|
|
int err;
|
||
|
|
|
||
|
|
err = squashfs_read_metadata(sb, &disk_id, &start_block, &offset,
|
||
|
|
sizeof(disk_id));
|
||
|
|
if (err < 0)
|
||
|
|
return err;
|
||
|
|
|
||
|
|
*id = le32_to_cpu(disk_id);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Read uncompressed id lookup table indexes from disk into memory
|
||
|
|
*/
|
||
|
|
__le64 *squashfs_read_id_index_table(struct super_block *sb,
|
||
|
|
u64 id_table_start, u64 next_table, unsigned short no_ids)
|
||
|
|
{
|
||
|
|
unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids);
|
||
|
|
__le64 *table;
|
||
|
|
|
||
|
|
TRACE("In read_id_index_table, length %d\n", length);
|
||
|
|
|
||
|
|
/* Sanity check values */
|
||
|
|
|
||
|
|
/* there should always be at least one id */
|
||
|
|
if (no_ids == 0)
|
||
|
|
return ERR_PTR(-EINVAL);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* length bytes should not extend into the next table - this check
|
||
|
|
* also traps instances where id_table_start is incorrectly larger
|
||
|
|
* than the next table start
|
||
|
|
*/
|
||
|
|
if (id_table_start + length > next_table)
|
||
|
|
return ERR_PTR(-EINVAL);
|
||
|
|
|
||
|
|
table = squashfs_read_table(sb, id_table_start, length);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* table[0] points to the first id lookup table metadata block, this
|
||
|
|
* should be less than id_table_start
|
||
|
|
*/
|
||
|
|
if (!IS_ERR(table) && le64_to_cpu(table[0]) >= id_table_start) {
|
||
|
|
kfree(table);
|
||
|
|
return ERR_PTR(-EINVAL);
|
||
|
|
}
|
||
|
|
|
||
|
|
return table;
|
||
|
|
}
|