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/*
* Squashfs - a compressed read only filesystem for Linux
*
* Copyright (c) 2010
* 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.
*
* xattr_id.c
*/
/*
* This file implements code to map the 32-bit xattr id stored in the inode
* into the on disk location of the xattr data.
*/
#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/slab.h>
#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs.h"
#include "xattr.h"
/*
* Map xattr id using the xattr id look up table
*/
int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
int *count, unsigned int *size, unsigned long long *xattr)
{
struct squashfs_sb_info *msblk = sb->s_fs_info;
int block = SQUASHFS_XATTR_BLOCK(index);
int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
u64 start_block;
struct squashfs_xattr_id id;
int err;
if (index >= msblk->xattr_ids)
return -EINVAL;
start_block = le64_to_cpu(msblk->xattr_id_table[block]);
err = squashfs_read_metadata(sb, &id, &start_block, &offset,
sizeof(id));
if (err < 0)
return err;
*xattr = le64_to_cpu(id.xattr);
*size = le32_to_cpu(id.size);
*count = le32_to_cpu(id.count);
return 0;
}
/*
* Read uncompressed xattr id lookup table indexes from disk into memory
*/
__le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 table_start,
u64 *xattr_table_start, int *xattr_ids)
{
struct squashfs_sb_info *msblk = sb->s_fs_info;
unsigned int len, indexes;
struct squashfs_xattr_id_table *id_table;
__le64 *table;
u64 start, end;
int n;
id_table = squashfs_read_table(sb, table_start, sizeof(*id_table));
if (IS_ERR(id_table))
return (__le64 *) id_table;
*xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
*xattr_ids = le32_to_cpu(id_table->xattr_ids);
kfree(id_table);
/* Sanity check values */
/* there is always at least one xattr id */
if (*xattr_ids == 0)
return ERR_PTR(-EINVAL);
len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
indexes = SQUASHFS_XATTR_BLOCKS(*xattr_ids);
/*
* The computed size of the index table (len bytes) should exactly
* match the table start and end points
*/
start = table_start + sizeof(*id_table);
end = msblk->bytes_used;
if (len != (end - start))
return ERR_PTR(-EINVAL);
table = squashfs_read_table(sb, start, len);
if (IS_ERR(table))
return table;
/* table[0], table[1], ... table[indexes - 1] store the locations
* of the compressed xattr id blocks. Each entry should be less than
* the next (i.e. table[0] < table[1]), and the difference between them
* should be SQUASHFS_METADATA_SIZE or less. table[indexes - 1]
* should be less than table_start, and again the difference
* shouls be SQUASHFS_METADATA_SIZE or less.
*
* Finally xattr_table_start should be less than table[0].
*/
for (n = 0; n < (indexes - 1); n++) {
start = le64_to_cpu(table[n]);
end = le64_to_cpu(table[n + 1]);
if (start >= end || (end - start) >
(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
kfree(table);
return ERR_PTR(-EINVAL);
}
}
start = le64_to_cpu(table[indexes - 1]);
if (start >= table_start || (table_start - start) >
(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
kfree(table);
return ERR_PTR(-EINVAL);
}
if (*xattr_table_start >= le64_to_cpu(table[0])) {
kfree(table);
return ERR_PTR(-EINVAL);
}
return table;
}
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