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/*
File: file_cow.c
Copyright (C) 2009 Christophe GRENIER <grenier@cgsecurity.org>
This software 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 of the License, 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 the Free Software Foundation, Inc., 51
Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#if !defined(SINGLE_FORMAT) || defined(SINGLE_FORMAT_cow)
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include <stdio.h>
#include "types.h"
#include "filegen.h"
#include "common.h"
#include "log.h"
/*@ requires valid_register_header_check(file_stat); */
static void register_header_check_cow(file_stat_t *file_stat);
const file_hint_t file_hint_cow= {
.extension="cow",
.description="Qemu Image",
.max_filesize=PHOTOREC_MAX_FILE_SIZE,
.recover=1,
.enable_by_default=1,
.register_header_check=®ister_header_check_cow
};
/* QEMU, open source processor emulator, can be downloaded from http://www.qemu.org/ */
typedef struct {
uint32_t magic;
uint32_t version;
uint64_t backing_file_offset;
uint32_t backing_file_size;
uint32_t mtime;
uint64_t size; /* in bytes */
uint8_t cluster_bits;
uint8_t l2_bits;
uint32_t crypt_method;
uint64_t l1_table_offset;
} __attribute__ ((gcc_struct, __packed__)) QCowHeader_t;
typedef struct QCowHeader {
uint32_t magic;
uint32_t version;
uint64_t backing_file_offset;
uint32_t backing_file_size;
uint32_t cluster_bits;
uint64_t size; /* in bytes */
uint32_t crypt_method;
uint32_t l1_size; /* XXX: save number of clusters instead ? */
uint64_t l1_table_offset;
uint64_t refcount_table_offset;
uint32_t refcount_table_clusters;
uint32_t nb_snapshots;
uint64_t snapshots_offset;
} QCowHeader2_t;
/*@
@ requires buffer_size >= sizeof(QCowHeader_t);
@ requires separation: \separated(&file_hint_cow, buffer+(..), file_recovery, file_recovery_new);
@ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
@ ensures valid_header_check_result(\result, file_recovery_new);
@ assigns *file_recovery_new;
@*/
static int header_check_qcow1(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
{
const QCowHeader_t *header=(const QCowHeader_t*)buffer;
uint64_t min_size=be64(header->backing_file_offset);
if(min_size < be64(header->l1_table_offset))
min_size=be64(header->l1_table_offset);
reset_file_recovery(file_recovery_new);
file_recovery_new->extension=file_hint_cow.extension;
file_recovery_new->time=be32(header->mtime);
file_recovery_new->min_filesize=min_size;
return 1;
}
/*@
@ requires buffer_size >= sizeof(QCowHeader2_t);
@ requires separation: \separated(&file_hint_cow, buffer+(..), file_recovery, file_recovery_new);
@ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
@ ensures valid_header_check_result(\result, file_recovery_new);
@ assigns *file_recovery_new;
@*/
static int header_check_qcow2(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
{
const QCowHeader2_t *header=(const QCowHeader2_t*)buffer;
uint64_t min_size=be64(header->backing_file_offset);
if(min_size < be64(header->l1_table_offset))
min_size=be64(header->l1_table_offset);
else if(min_size < be64(header->refcount_table_offset))
min_size=be64(header->refcount_table_offset);
else if(min_size < be64(header->snapshots_offset))
min_size=be64(header->snapshots_offset);
reset_file_recovery(file_recovery_new);
file_recovery_new->extension=file_hint_cow.extension;
file_recovery_new->min_filesize=min_size;
#ifdef DEBUG_COW
log_info("magic %lu\n", be32(header->magic));
log_info("version %lu\n", be32(header->version));
log_info("backing_file_offset %llu\n", be64(header->backing_file_offset));
log_info("backing_file_size %lu\n", be32(header->backing_file_size));
log_info("cluster_bits %lu\n", be32(header->cluster_bits));
log_info("size %llu\n", be64(header->size)); /* in bytes */
log_info("crypt_method %lu\n", be32(header->crypt_method));
log_info("l1_size %lu\n", be32(header->l1_size)); /* XXX: save number of clusters instead ? */
log_info("l1_table_offset %llu\n", be64(header->l1_table_offset));
log_info("refcount_table_offset %llu\n", be64(header->refcount_table_offset));
log_info("refcount_table_clusters %lu\n", be32(header->refcount_table_clusters));
log_info("nb_snapshots %lu\n", be32(header->nb_snapshots));
log_info("snapshots_offset %llu\n", be64(header->snapshots_offset));
#endif
return 1;
}
static void register_header_check_cow(file_stat_t *file_stat)
{
static const unsigned char cow_header[8]= {'Q', 'F', 'I', 0xfb, 0x0, 0x0, 0x0, 0x1};
static const unsigned char cow_header2[8]= {'Q', 'F', 'I', 0xfb, 0x0, 0x0, 0x0, 0x2};
static const unsigned char cow_header3[8]= {'Q', 'F', 'I', 0xfb, 0x0, 0x0, 0x0, 0x3};
register_header_check(0, cow_header,sizeof(cow_header), &header_check_qcow1, file_stat);
register_header_check(0, cow_header2,sizeof(cow_header2), &header_check_qcow2, file_stat);
register_header_check(0, cow_header3,sizeof(cow_header3), &header_check_qcow2, file_stat);
}
#endif
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