/*
* Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2007-2013 Sourcefire, Inc.
*
* Authors: Tomasz Kojm
*
* 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 <assert.h>
#include "clamav.h"
#include "memory.h"
#include "others.h"
#include "matcher.h"
#include "matcher-bm.h"
#include "filetypes.h"
#include "filtering.h"
#include "mpool.h"
#define BM_MIN_LENGTH 3
#define BM_BLOCK_SIZE 3
#define HASH(a, b, c) (211 * a + 37 * b + c)
cl_error_t cli_bm_addpatt(struct cli_matcher *root, struct cli_bm_patt *pattern, const char *offset)
{
uint16_t idx, i;
const unsigned char *pt = pattern->pattern;
struct cli_bm_patt *prev, *next = NULL;
cl_error_t ret;
if (pattern->length < BM_MIN_LENGTH) {
cli_errmsg("cli_bm_addpatt: Signature for %s is too short\n", pattern->virname);
return CL_EMALFDB;
}
if (CL_SUCCESS != (ret = cli_caloff(offset, NULL, root->type, pattern->offdata, &pattern->offset_min, &pattern->offset_max))) {
cli_errmsg("cli_bm_addpatt: Can't calculate offset for signature %s\n", pattern->virname);
return ret;
}
if (pattern->offdata[0] != CLI_OFF_ANY) {
if (pattern->offdata[0] == CLI_OFF_ABSOLUTE)
root->bm_absoff_num++;
else
root->bm_reloff_num++;
}
/* bm_offmode doesn't use the prefilter for BM signatures anyway, so
* don't add these to the filter. */
if (root->filter && !root->bm_offmode) {
/* the bm_suffix load balancing below can shorten the sig,
* we want to see the entire signature! */
if (filter_add_static(root->filter, pattern->pattern, pattern->length, pattern->virname) == -1) {
cli_warnmsg("cli_bm_addpatt: cannot use filter for trie\n");
MPOOL_FREE(root->mempool, root->filter);
root->filter = NULL;
}
/* TODO: should this affect maxpatlen? */
}
#if BM_MIN_LENGTH == BM_BLOCK_SIZE
/* try to load balance bm_suffix (at the cost of bm_shift) */
for (i = 0; i < pattern->length - BM_BLOCK_SIZE + 1; i++) {
idx = HASH(pt[i], pt[i + 1], pt[i + 2]);
if (!root->bm_suffix[idx]) {
if (i) {
pattern->prefix = pattern->pattern;
pattern->prefix_length = i;
pattern->pattern = &pattern->pattern[i];
pattern->length -= i;
pt = pattern->pattern;
}
break;
}
}
#endif
for (i = 0; i <= BM_MIN_LENGTH - BM_BLOCK_SIZE; i++) {
idx = HASH(pt[i], pt[i + 1], pt[i + 2]);
root->bm_shift[idx] = MIN(root->bm_shift[idx], BM_MIN_LENGTH - BM_BLOCK_SIZE - i);
}
prev = next = root->bm_suffix[idx];
while (next) {
if (pt[0] >= next->pattern0)
break;
prev = next;
next = next->next;
}
if (next == root->bm_suffix[idx]) {
pattern->next = root->bm_suffix[idx];
if (root->bm_suffix[idx])
pattern->cnt = root->bm_suffix[idx]->cnt;
root->bm_suffix[idx] = pattern;
} else {
pattern->next = prev->next;
prev->next = pattern;
}
pattern->pattern0 = pattern->pattern[0];
root->bm_suffix[idx]->cnt++;
if (root->bm_offmode) {
root->bm_pattab = (struct cli_bm_patt **)MPOOL_REALLOC2(root->mempool, root->bm_pattab, (root->bm_patterns + 1) * sizeof(struct cli_bm_patt *));
if (!root->bm_pattab) {
cli_errmsg("cli_bm_addpatt: Can't allocate memory for root->bm_pattab\n");
return CL_EMEM;
}
root->bm_pattab[root->bm_patterns] = pattern;
if (pattern->offdata[0] != CLI_OFF_ABSOLUTE)
pattern->offset_min = root->bm_patterns;
}
root->bm_patterns++;
return CL_SUCCESS;
}
cl_error_t cli_bm_init(struct cli_matcher *root)
{
uint16_t i, size = HASH(255, 255, 255) + 1;
#ifdef USE_MPOOL
assert(root->mempool && "mempool must be initialized");
#endif
if (!(root->bm_shift = (uint8_t *)MPOOL_CALLOC(root->mempool, size, sizeof(uint8_t))))
return CL_EMEM;
if (!(root->bm_suffix = (struct cli_bm_patt **)MPOOL_CALLOC(root->mempool, size, sizeof(struct cli_bm_patt *)))) {
MPOOL_FREE(root->mempool, root->bm_shift);
return CL_EMEM;
}
for (i = 0; i < size; i++)
root->bm_shift[i] = BM_MIN_LENGTH - BM_BLOCK_SIZE + 1;
return CL_SUCCESS;
}
cl_error_t cli_bm_initoff(const struct cli_matcher *root, struct cli_bm_off *data, const struct cli_target_info *info)
{
cl_error_t ret;
unsigned int i;
struct cli_bm_patt *patt;
if (!root->bm_patterns) {
data->offtab = data->offset = NULL;
data->cnt = data->pos = 0;
return CL_SUCCESS;
}
data->cnt = data->pos = 0;
data->offtab = (uint32_t *)cli_malloc(root->bm_patterns * sizeof(uint32_t));
if (!data->offtab) {
cli_errmsg("cli_bm_initoff: Can't allocate memory for data->offtab\n");
return CL_EMEM;
}
data->offset = (uint32_t *)cli_malloc(root->bm_patterns * sizeof(uint32_t));
if (!data->offset) {
cli_errmsg("cli_bm_initoff: Can't allocate memory for data->offset\n");
free(data->offtab);
return CL_EMEM;
}
for (i = 0; i < root->bm_patterns; i++) {
patt = root->bm_pattab[i];
if (patt->offdata[0] == CLI_OFF_ABSOLUTE) {
data->offtab[data->cnt] = patt->offset_min + patt->prefix_length;
if (data->offtab[data->cnt] >= info->fsize)
continue;
data->cnt++;
} else if (CL_SUCCESS != (ret = cli_caloff(NULL, info, root->type, patt->offdata, &data->offset[patt->offset_min], NULL))) {
cli_errmsg("cli_bm_initoff: Can't calculate relative offset in signature for %s\n", patt->virname);
free(data->offtab);
free(data->offset);
return ret;
} else if ((data->offset[patt->offset_min] != CLI_OFF_NONE) && (data->offset[patt->offset_min] + patt->length <= info->fsize)) {
if (!data->cnt || (data->offset[patt->offset_min] + patt->prefix_length != data->offtab[data->cnt - 1])) {
data->offtab[data->cnt] = data->offset[patt->offset_min] + patt->prefix_length;
if (data->offtab[data->cnt] >= info->fsize)
continue;
data->cnt++;
}
}
}
cli_qsort(data->offtab, data->cnt, sizeof(uint32_t), NULL);
return CL_SUCCESS;
}
void cli_bm_freeoff(struct cli_bm_off *data)
{
free(data->offset);
data->offset = NULL;
free(data->offtab);
data->offtab = NULL;
}
void cli_bm_free(struct cli_matcher *root)
{
struct cli_bm_patt *patt, *prev;
uint16_t i, size = HASH(255, 255, 255) + 1;
if (root->bm_shift)
MPOOL_FREE(root->mempool, root->bm_shift);
if (root->bm_pattab)
MPOOL_FREE(root->mempool, root->bm_pattab);
if (root->bm_suffix) {
for (i = 0; i < size; i++) {
patt = root->bm_suffix[i];
while (patt) {
prev = patt;
patt = patt->next;
if (prev->prefix)
MPOOL_FREE(root->mempool, prev->prefix);
else
MPOOL_FREE(root->mempool, prev->pattern);
if (prev->virname)
MPOOL_FREE(root->mempool, prev->virname);
MPOOL_FREE(root->mempool, prev);
}
}
MPOOL_FREE(root->mempool, root->bm_suffix);
}
}
cl_error_t cli_bm_scanbuff(const unsigned char *buffer, uint32_t length, const char **virname, const struct cli_bm_patt **patt, const struct cli_matcher *root, uint32_t offset, const struct cli_target_info *info, struct cli_bm_off *offdata, cli_ctx *ctx)
{
uint32_t i, j, off, off_min, off_max;
uint8_t found, pchain, shift;
uint16_t idx, idxchk;
struct cli_bm_patt *p;
const unsigned char *bp, *pt;
unsigned char prefix;
cl_error_t ret;
int viruses_found = 0;
if (!root || !root->bm_shift)
return CL_CLEAN;
if (length < BM_MIN_LENGTH)
return CL_CLEAN;
i = BM_MIN_LENGTH - BM_BLOCK_SIZE;
if (offdata) {
if (!offdata->cnt)
return CL_CLEAN;
if (offdata->pos == offdata->cnt)
offdata->pos--;
for (; offdata->pos && offdata->offtab[offdata->pos] > offset; offdata->pos--)
;
if (offdata->offtab[offdata->pos] < offset)
offdata->pos++;
if (offdata->pos >= offdata->cnt)
return CL_CLEAN;
i += offdata->offtab[offdata->pos] - offset;
}
for (; i < length - BM_BLOCK_SIZE + 1;) {
idx = HASH(buffer[i], buffer[i + 1], buffer[i + 2]);
shift = root->bm_shift[idx];
if (shift == 0) {
prefix = buffer[i - BM_MIN_LENGTH + BM_BLOCK_SIZE];
p = root->bm_suffix[idx];
if (p && p->cnt == 1 && p->pattern0 != prefix) {
if (offdata) {
off = offset + i - BM_MIN_LENGTH + BM_BLOCK_SIZE;
for (; offdata->pos < offdata->cnt && off >= offdata->offtab[offdata->pos]; offdata->pos++)
;
if (offdata->pos == offdata->cnt || off >= offdata->offtab[offdata->pos]) {
if (viruses_found)
return CL_VIRUS;
return CL_CLEAN;
}
i += offdata->offtab[offdata->pos] - off;
} else {
i++;
}
continue;
}
pchain = 0;
while (p) {
if (p->pattern0 != prefix) {
if (pchain)
break;
p = p->next;
continue;
} else
pchain = 1;
off = i - BM_MIN_LENGTH + BM_BLOCK_SIZE;
bp = buffer + off;
if ((off + p->length > length) || (p->prefix_length > off)) {
p = p->next;
continue;
}
if (offdata) {
if (p->offdata[0] == CLI_OFF_ABSOLUTE) {
if (p->offset_min != offset + off - p->prefix_length) {
p = p->next;
continue;
}
} else if ((offdata->offset[p->offset_min] == CLI_OFF_NONE) || (offdata->offset[p->offset_min] != offset + off - p->prefix_length)) {
p = p->next;
continue;
}
}
idxchk = MIN(p->length, length - off) - 1;
if (idxchk) {
if ((bp[idxchk] != p->pattern[idxchk]) || (bp[idxchk / 2] != p->pattern[idxchk / 2])) {
p = p->next;
continue;
}
}
if (p->prefix_length) {
off -= p->prefix_length;
bp -= p->prefix_length;
pt = p->prefix;
} else {
pt = p->pattern;
}
found = 1;
for (j = 0; j < p->length + p->prefix_length && off < length; j++, off++) {
if (bp[j] != pt[j]) {
found = 0;
break;
}
}
if (found && (p->boundary & BM_BOUNDARY_EOL)) {
if (off != length) {
p = p->next;
continue;
}
}
if (found && p->length + p->prefix_length == j) {
if (!offdata && (p->offset_min != CLI_OFF_ANY)) {
if (p->offdata[0] != CLI_OFF_ABSOLUTE) {
if (!info) {
p = p->next;
continue;
}
ret = cli_caloff(NULL, info, root->type, p->offdata, &off_min, &off_max);
if (ret != CL_SUCCESS) {
cli_errmsg("cli_bm_scanbuff: Can't calculate relative offset in signature for %s\n", p->virname);
return ret;
}
} else {
off_min = p->offset_min;
off_max = p->offset_max;
}
off = offset + i - p->prefix_length - BM_MIN_LENGTH + BM_BLOCK_SIZE;
if (off_min == CLI_OFF_NONE || off_max < off || off_min > off) {
p = p->next;
continue;
}
}
if (virname) {
*virname = p->virname;
if (ctx != NULL && SCAN_ALLMATCHES) {
cli_append_virus(ctx, *virname);
//*viroffset = offset + i + j - BM_MIN_LENGTH + BM_BLOCK_SIZE;
}
}
if (patt)
*patt = p;
viruses_found = 1;
if (ctx != NULL && !SCAN_ALLMATCHES)
return CL_VIRUS;
}
p = p->next;
}
shift = 1;
}
if (offdata) {
off = offset + i - BM_MIN_LENGTH + BM_BLOCK_SIZE;
for (; offdata->pos < offdata->cnt && off >= offdata->offtab[offdata->pos]; offdata->pos++)
;
if (offdata->pos == offdata->cnt || off >= offdata->offtab[offdata->pos]) {
if (viruses_found)
return CL_VIRUS;
return CL_CLEAN;
}
i += offdata->offtab[offdata->pos] - off;
} else {
i += shift;
}
}
if (viruses_found)
return CL_VIRUS;
return CL_CLEAN;
}