/*
* Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2010-2013 Sourcefire, Inc.
*
* Authors: aCaB <acab@clamav.net>
*
* 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 <string.h>
#include "scanners.h"
#include "others.h"
#include "clamav.h"
#include "fmap.h"
#include "binhex.h"
// clang-format off
static const uint8_t hqxtbl[] = {
/* 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f */
/* 00-0f */ 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
/* 10-1f */ 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
/* 20-2f */ 0xff,0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0xff,0xff,
/* 30-3f */ 0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0xff,0x14,0x15,0xff,0xff,0xff,0xff,0xff,0xff,
/* 40-4f */ 0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f,0x20,0x21,0x22,0x23,0x24,0xff,
/* 50-5f */ 0x25,0x26,0x27,0x28,0x29,0x2a,0x2b,0xff,0x2c,0x2d,0x2e,0x2f,0xff,0xff,0xff,0xff,
/* 60-6f */ 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0xff,0x37,0x38,0x39,0x3a,0x3b,0x3c,0xff,0xff,
/* 70-7f */ 0x3d,0x3e,0x3f,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
};
// clang-format on
#define BH_FLUSH_SZ (BUFSIZ - 256)
int cli_binhex(cli_ctx *ctx)
{
fmap_t *map = *ctx->fmap;
const uint8_t *encoded = NULL;
uint8_t decoded[BUFSIZ], spare_bits = 0, last_byte = 0, this_byte = 0, offset = 0;
size_t enc_done = 0, enc_todo = map->len;
unsigned int dec_done = 0, chunksz = 0, chunkoff = 0;
uint32_t datalen = 0, reslen = 0;
int in_data = 0, in_run = 0, datafd, resfd, ret = CL_CLEAN;
enum binhex_phase { IN_BANNER,
IN_HEADER,
IN_DATA,
IN_LIMBO1,
IN_LIMBO2,
IN_RES } write_phase = IN_BANNER;
char *dname, *rname;
cli_dbgmsg("in cli_binhex\n");
if (!map->len) return CL_CLEAN;
if ((ret = cli_gentempfd(ctx->engine->tmpdir, &dname, &datafd)) != CL_SUCCESS)
return ret;
if ((ret = cli_gentempfd(ctx->engine->tmpdir, &rname, &resfd)) != CL_SUCCESS) {
close(datafd);
if (cli_unlink(dname)) ret = CL_EUNLINK;
free(dname);
return ret;
}
memset(decoded, 0, 24);
while (1) {
uint8_t b;
if (!enc_todo || dec_done >= BH_FLUSH_SZ) {
if (write_phase == IN_HEADER) {
uint32_t namelen = (uint32_t)decoded[0], hdrlen = 1 + namelen + 1 + 4 + 4 + 2;
if (!dec_done) {
cli_dbgmsg("cli_binhex: file is empty\n");
break;
}
datalen = (decoded[hdrlen] << 24) | (decoded[hdrlen + 1] << 16) | (decoded[hdrlen + 2] << 8) | decoded[hdrlen + 3];
hdrlen += 4;
reslen = (decoded[hdrlen] << 24) | (decoded[hdrlen + 1] << 16) | (decoded[hdrlen + 2] << 8) | decoded[hdrlen + 3];
hdrlen += 4 + 2;
decoded[namelen + 1] = 0;
if (dec_done <= hdrlen) {
cli_dbgmsg("cli_binhex: file too short for header\n");
break;
}
if ((ret = cli_checklimits("cli_binhex(data)", ctx, datalen, 0, 0)) != CL_CLEAN)
break;
if (cli_checklimits("cli_binhex(resources)", ctx, reslen, 0, 0) != CL_CLEAN)
reslen = 0;
cli_dbgmsg("cli_binhex: decoding '%s' - %u bytes of data to %s - %u bytes or resources to %s\n", decoded + 1, datalen, dname, reslen, rname);
memmove(decoded, &decoded[hdrlen], dec_done - hdrlen);
dec_done -= hdrlen;
write_phase++;
}
if (dec_done && write_phase == IN_DATA) {
unsigned int todo = MIN(dec_done, datalen);
datalen -= todo;
dec_done -= todo;
if (cli_writen(datafd, decoded, todo) != todo) {
ret = CL_EWRITE;
break;
}
if (!datalen) {
write_phase++;
if (lseek(datafd, 0, SEEK_SET) == -1) {
cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
ret = CL_ESEEK;
break;
}
ret = cli_magic_scandesc(datafd, dname, ctx);
if (ret == CL_VIRUS) break;
}
if (dec_done)
memmove(decoded, &decoded[todo], dec_done);
}
if (dec_done && write_phase == IN_LIMBO1) {
if (dec_done > 1) {
if (reslen < 5) {
cli_dbgmsg("cli_binhex: skipping resources (too small)\n");
break;
}
dec_done -= 2;
write_phase += 2;
if (dec_done)
memmove(decoded, &decoded[2], dec_done);
} else {
dec_done--;
write_phase++;
if (dec_done)
memmove(decoded, &decoded[1], dec_done);
}
}
if (dec_done && write_phase == IN_LIMBO2) {
if (reslen < 5) {
cli_dbgmsg("cli_binhex: skipping resources (too small)\n");
break;
}
write_phase++;
if (--dec_done)
memmove(decoded, &decoded[1], dec_done);
}
if (dec_done && write_phase == IN_RES) {
unsigned int todo = MIN(dec_done, reslen);
reslen -= todo;
dec_done -= todo;
if (cli_writen(resfd, decoded, todo) != todo) {
ret = CL_EWRITE;
break;
}
if (!reslen) {
if (lseek(resfd, 0, SEEK_SET) == -1) {
cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
ret = CL_ESEEK;
break;
}
ret = cli_magic_scandesc(resfd, rname, ctx);
break;
}
}
if (!enc_todo) {
if (write_phase == IN_DATA) {
cli_dbgmsg("cli_binhex: scanning partially extracted data fork\n");
if (lseek(datafd, 0, SEEK_SET) == -1) {
cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
ret = CL_ESEEK;
break;
}
ret = cli_magic_scandesc(datafd, dname, ctx);
} else if (write_phase == IN_RES) {
cli_dbgmsg("cli_binhex: scanning partially extracted resource fork\n");
if (lseek(resfd, 0, SEEK_SET) == -1) {
cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
ret = CL_ESEEK;
break;
}
ret = cli_magic_scandesc(resfd, rname, ctx);
}
break;
}
}
// 'chunksz' must be 0 the first iteration,
// so that 'encoded' will be initialized before first dereference.
if (!chunksz) {
chunksz = MIN(enc_todo, map->pgsz);
encoded = fmap_need_off_once(map, enc_done, chunksz);
if (!encoded) {
ret = CL_EREAD;
break;
}
chunkoff = 0;
}
chunksz--;
b = encoded[chunkoff++];
enc_done++;
enc_todo--;
if ((char)b == '\r' || (char)b == '\n') {
in_data = 1;
continue;
}
if (!in_data) continue;
if (write_phase == IN_BANNER) {
if ((char)b != ':') {
cli_dbgmsg("cli_binhex: broken file (missing stream start identifier)\n");
break;
}
write_phase++;
}
if ((char)b == ':')
continue;
if (b > 0x7f || (b = hqxtbl[b]) == 0xff) {
cli_dbgmsg("cli_binhex: Invalid character (%02x)\n", encoded[chunkoff - 1]);
break;
}
switch ((offset++) & 3) { /* 6 bits per char */
case 0: /* left-6h */
spare_bits = b << 2;
continue;
case 1: /* left-2l + middle-4h */
this_byte = spare_bits | (b >> 4);
spare_bits = b << 4;
break;
case 2: /* middle-4l + right-2h */
this_byte = spare_bits | (b >> 2);
spare_bits = b << 6;
break;
case 3: /* right-6l */
this_byte = spare_bits | b;
}
if (in_run) {
in_run = 0;
if (!this_byte)
this_byte = 0x90;
else {
while (--this_byte)
decoded[dec_done++] = last_byte;
continue;
}
} else if (this_byte == 0x90) {
in_run = 1;
continue;
}
decoded[dec_done++] = this_byte;
last_byte = this_byte;
}
close(datafd);
close(resfd);
if (!ctx->engine->keeptmp) {
if (cli_unlink(dname) && ret != CL_VIRUS) ret = CL_EUNLINK;
if (cli_unlink(rname) && ret != CL_VIRUS) ret = CL_EUNLINK;
}
free(dname);
free(rname);
return ret;
}