Stowage/clamav
2
0
Fork 0
mirror of https://github.com/Cisco-Talos/clamav.git synced 2025-10-19 10:23:17 +00:00
Code Issues Projects Releases Packages Wiki Activity
clamav/libclamav/binhex.c
Micah Snyder cd3134568a Code quality: Refactor layer attributes as scan parameter 
The current implementation sets a "next layer attributes" flag field
in the scan context. This may introduce bugs if accidentally not cleared
during error handling, causing that attribute to be applied to a
different layer than intended.

This commit resolves that by adding an attribute flag to the major
internal scan functions and removing the "next layer attributes" from
the scan context. This attributes flag shares the same flag fields as
the attributes flag in the new file inspection callback and the flags
are defined in `clamav.h`.
2022-10-13 08:57:44 -07:00

274 lines
10 KiB
C
Raw Blame History

/*
* Copyright (C) 2013-2022 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->sub_tmpdir, &dname, &datafd)) != CL_SUCCESS)
return ret;
if ((ret = cli_gentempfd(ctx->sub_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_scan_desc(datafd, dname, ctx, NULL, LAYER_ATTRIBUTES_NONE);
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_scan_desc(resfd, rname, ctx, NULL, LAYER_ATTRIBUTES_NONE);
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_scan_desc(datafd, dname, ctx, NULL, LAYER_ATTRIBUTES_NONE);
} 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_scan_desc(resfd, rname, ctx, NULL, LAYER_ATTRIBUTES_NONE);
}
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;
}
Reference in a new issue View git blame Copy permalink