/*
* Copyright (C) 2014-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
*
* Authors: Kevin Lin <kevlin2@cisco.com>
*
* 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 Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <stdio.h>
#include <errno.h>
#if HAVE_STRING_H
#include <string.h>
#endif
#include <ctype.h>
#include <fcntl.h>
#include "clamav-types.h"
#include "others.h"
#include "apm.h"
#include "prtn_intxn.h"
#include "scanners.h"
#include "dconf.h"
//#define DEBUG_APM_PARSE
#ifdef DEBUG_APM_PARSE
# define apm_parsemsg(...) cli_dbgmsg( __VA_ARGS__)
#else
# define apm_parsemsg(...) ;
#endif
static int apm_prtn_intxn(cli_ctx *ctx, struct apm_partition_info *aptable, size_t sectorsize, int old_school);
int cli_scanapm(cli_ctx *ctx)
{
struct apm_driver_desc_map ddm;
struct apm_partition_info aptable, apentry;
int ret = CL_CLEAN, detection = CL_CLEAN, old_school = 0;
size_t sectorsize, maplen, partsize;
off_t pos = 0, partoff = 0;
unsigned i;
uint32_t max_prtns = 0;
if (!ctx || !ctx->fmap) {
cli_errmsg("cli_scanapm: Invalid context\n");
return CL_ENULLARG;
}
/* read driver description map at sector 0 */
if (fmap_readn(*ctx->fmap, &ddm, pos, sizeof(ddm)) != sizeof(ddm)) {
cli_dbgmsg("cli_scanapm: Invalid Apple driver description map\n");
return CL_EFORMAT;
}
/* convert driver description map big-endian to host */
ddm.signature = be16_to_host(ddm.signature);
ddm.blockSize = be16_to_host(ddm.blockSize);
ddm.blockCount = be32_to_host(ddm.blockCount);
/* check DDM signature */
if (ddm.signature != DDM_SIGNATURE) {
cli_dbgmsg("cli_scanapm: Apple driver description map signature mismatch\n");
return CL_EFORMAT;
}
/* sector size is determined by the ddm */
sectorsize = ddm.blockSize;
/* size of total file must be described by the ddm */
maplen = (*ctx->fmap)->real_len;
if ((ddm.blockSize * ddm.blockCount) != maplen) {
cli_dbgmsg("cli_scanapm: File described %u size does not match %lu actual size\n",
(ddm.blockSize * ddm.blockCount), (unsigned long)maplen);
return CL_EFORMAT;
}
/* check for old-school partition map */
if (sectorsize == 2048) {
if (fmap_readn(*ctx->fmap, &aptable, APM_FALLBACK_SECTOR_SIZE, sizeof(aptable)) != sizeof(aptable)) {
cli_dbgmsg("cli_scanapm: Invalid Apple partition entry\n");
return CL_EFORMAT;
}
aptable.signature = be16_to_host(aptable.signature);
if (aptable.signature == APM_SIGNATURE) {
sectorsize = APM_FALLBACK_SECTOR_SIZE;
old_school = 1;
}
}
/* read partition table at sector 1 (or after the ddm if old-school) */
pos = APM_PTABLE_BLOCK * sectorsize;
if (fmap_readn(*ctx->fmap, &aptable, pos, sizeof(aptable)) != sizeof(aptable)) {
cli_dbgmsg("cli_scanapm: Invalid Apple partition table\n");
return CL_EFORMAT;
}
/* convert partition table big endian to host */
aptable.signature = be16_to_host(aptable.signature);
aptable.numPartitions = be32_to_host(aptable.numPartitions);
aptable.pBlockStart = be32_to_host(aptable.pBlockStart);
aptable.pBlockCount = be32_to_host(aptable.pBlockCount);
/* check the partition entry signature */
if (aptable.signature != APM_SIGNATURE) {
cli_dbgmsg("cli_scanapm: Apple partition table signature mismatch\n");
return CL_EFORMAT;
}
/* check if partition table partition */
if (strncmp((char*)aptable.type, "Apple_Partition_Map", 32) &&
strncmp((char*)aptable.type, "Apple_partition_map", 32) &&
strncmp((char*)aptable.type, "Apple_patition_map", 32)){
cli_dbgmsg("cli_scanapm: Initial Apple Partition Map partition is not detected\n");
return CL_EFORMAT;
}
/* check that the partition table fits in the space specified - HEURISTICS */
if (SCAN_HEURISTIC_PARTITION_INTXN && (ctx->dconf->other & OTHER_CONF_PRTNINTXN)) {
ret = apm_prtn_intxn(ctx, &aptable, sectorsize, old_school);
if (ret != CL_CLEAN) {
if (SCAN_ALLMATCHES && (ret == CL_VIRUS))
detection = CL_VIRUS;
else
return ret;
}
}
/* print debugging info on partition tables */
cli_dbgmsg("APM Partition Table:\n");
cli_dbgmsg("Name: %s\n", (char*)aptable.name);
cli_dbgmsg("Type: %s\n", (char*)aptable.type);
cli_dbgmsg("Signature: %x\n", aptable.signature);
cli_dbgmsg("Partition Count: %u\n", aptable.numPartitions);
cli_dbgmsg("Blocks: [%u, +%u), ([%lu, +%lu))\n",
aptable.pBlockStart, aptable.pBlockCount,
(unsigned long)(aptable.pBlockStart * sectorsize),
(unsigned long)(aptable.pBlockCount * sectorsize));
/* check engine maxpartitions limit */
if (aptable.numPartitions < ctx->engine->maxpartitions) {
max_prtns = aptable.numPartitions;
}
else {
max_prtns = ctx->engine->maxpartitions;
}
/* partition table is a partition [at index 1], so skip it */
for (i = 2; i <= max_prtns; ++i) {
/* read partition table entry */
pos = i * sectorsize;
if (fmap_readn(*ctx->fmap, &apentry, pos, sizeof(apentry)) != sizeof(apentry)) {
cli_dbgmsg("cli_scanapm: Invalid Apple partition entry\n");
return CL_EFORMAT;
}
/* convert partition entry big endian to host */
apentry.signature = be16_to_host(apentry.signature);
apentry.reserved = be16_to_host(apentry.reserved);
apentry.numPartitions = be32_to_host(apentry.numPartitions);
apentry.pBlockStart = be32_to_host(apentry.pBlockStart);
apentry.pBlockCount = be32_to_host(apentry.pBlockCount);
/* check the partition entry signature */
if (aptable.signature != APM_SIGNATURE) {
cli_dbgmsg("cli_scanapm: Apple partition entry signature mismatch\n");
return CL_EFORMAT;
}
/* check if a out-of-order partition map */
if (!strncmp((char*)apentry.type, "Apple_Partition_Map", 32) ||
!strncmp((char*)apentry.type, "Apple_partition_map", 32) ||
!strncmp((char*)apentry.type, "Apple_patition_map", 32)) {
cli_dbgmsg("cli_scanapm: Out of order Apple Partition Map partition\n");
continue;
}
partoff = apentry.pBlockStart * sectorsize;
partsize = apentry.pBlockCount * sectorsize;
/* re-calculate if old_school and aligned [512 * 4 => 2048] */
if (old_school && ((i % 4) == 0)) {
if (!strncmp((char*)apentry.type, "Apple_Driver", 32) ||
!strncmp((char*)apentry.type, "Apple_Driver43", 32) ||
!strncmp((char*)apentry.type, "Apple_Driver43_CD", 32) ||
!strncmp((char*)apentry.type, "Apple_Driver_ATA", 32) ||
!strncmp((char*)apentry.type, "Apple_Driver_ATAPI", 32) ||
!strncmp((char*)apentry.type, "Apple_Patches", 32)) {
partsize = apentry.pBlockCount * 2048;;
}
}
/* check if invalid partition */
if ((partoff == 0) || (partoff+partsize > maplen)) {
cli_dbgmsg("cli_scanapm: Detected invalid Apple partition entry\n");
continue;
}
/* print debugging info on partition */
cli_dbgmsg("APM Partition Entry %u:\n", i);
cli_dbgmsg("Name: %s\n", (char*)apentry.name);
cli_dbgmsg("Type: %s\n", (char*)apentry.type);
cli_dbgmsg("Signature: %x\n", apentry.signature);
cli_dbgmsg("Partition Count: %u\n", apentry.numPartitions);
cli_dbgmsg("Blocks: [%u, +%u), ([%lu, +%lu))\n",
apentry.pBlockStart, apentry.pBlockCount, (long unsigned)partoff, (long unsigned)partsize);
/* send the partition to cli_map_scan */
ret = cli_map_scan(*ctx->fmap, partoff, partsize, ctx, CL_TYPE_PART_ANY);
if (ret != CL_CLEAN) {
if (SCAN_ALLMATCHES && (ret == CL_VIRUS))
detection = CL_VIRUS;
else
return ret;
}
}
if (i >= ctx->engine->maxpartitions) {
cli_dbgmsg("cli_scanapm: max partitions reached\n");
}
return detection;
}
static int apm_prtn_intxn(cli_ctx *ctx, struct apm_partition_info *aptable, size_t sectorsize, int old_school)
{
prtn_intxn_list_t prtncheck;
struct apm_partition_info apentry;
unsigned i, pitxn;
int ret = CL_CLEAN, tmp = CL_CLEAN;
off_t pos;
uint32_t max_prtns = 0;
int virus_found = 0;
prtn_intxn_list_init(&prtncheck);
/* check engine maxpartitions limit */
if (aptable->numPartitions < ctx->engine->maxpartitions) {
max_prtns = aptable->numPartitions;
}
else {
max_prtns = ctx->engine->maxpartitions;
}
for (i = 1; i <= max_prtns; ++i) {
/* read partition table entry */
pos = i * sectorsize;
if (fmap_readn(*ctx->fmap, &apentry, pos, sizeof(apentry)) != sizeof(apentry)) {
cli_dbgmsg("cli_scanapm: Invalid Apple partition entry\n");
prtn_intxn_list_free(&prtncheck);
return CL_EFORMAT;
}
/* convert necessary info big endian to host */
apentry.pBlockStart = be32_to_host(apentry.pBlockStart);
apentry.pBlockCount = be32_to_host(apentry.pBlockCount);
/* re-calculate if old_school and aligned [512 * 4 => 2048] */
if (old_school && ((i % 4) == 0)) {
if (!strncmp((char*)apentry.type, "Apple_Driver", 32) ||
!strncmp((char*)apentry.type, "Apple_Driver43", 32) ||
!strncmp((char*)apentry.type, "Apple_Driver43_CD", 32) ||
!strncmp((char*)apentry.type, "Apple_Driver_ATA", 32) ||
!strncmp((char*)apentry.type, "Apple_Driver_ATAPI", 32) ||
!strncmp((char*)apentry.type, "Apple_Patches", 32)) {
apentry.pBlockCount = apentry.pBlockCount * 4;;
}
}
tmp = prtn_intxn_list_check(&prtncheck, &pitxn, apentry.pBlockStart, apentry.pBlockCount);
if (tmp != CL_CLEAN) {
if (tmp == CL_VIRUS) {
apm_parsemsg("Name: %s\n", (char*)aptable.name);
apm_parsemsg("Type: %s\n", (char*)aptable.type);
cli_dbgmsg("cli_scanapm: detected intersection with partitions "
"[%u, %u]\n", pitxn, i);
ret = cli_append_virus(ctx, PRTN_INTXN_DETECTION);
if (ret == CL_VIRUS)
virus_found = 1;
if (SCAN_ALLMATCHES || ret == CL_CLEAN)
tmp = 0;
else
goto leave;
} else {
ret = tmp;
goto leave;
}
}
pos += sectorsize;
}
leave:
prtn_intxn_list_free(&prtncheck);
if (virus_found)
return CL_VIRUS;
return ret;
}