/*
* Copyright (C) 2002 - 2005 Tomasz Kojm <tkojm@clamav.net>
*
* This program 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 to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <string.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "clamav.h"
#include "others.h"
#include "matcher-ac.h"
#include "matcher-bm.h"
#include "md5.h"
#include "filetypes.h"
#include "matcher.h"
#include "pe.h"
#include "special.h"
#define MD5_BLOCKSIZE 4096
#define TARGET_TABLE_SIZE 6
static int targettab[TARGET_TABLE_SIZE] = { 0, CL_TYPE_MSEXE, CL_TYPE_MSOLE2, CL_TYPE_HTML, CL_TYPE_MAIL, CL_TYPE_GRAPHICS };
extern short cli_debug_flag;
#ifdef CL_THREAD_SAFE
# include <pthread.h>
pthread_mutex_t cli_ref_mutex = PTHREAD_MUTEX_INITIALIZER;
#endif
int cli_scanbuff(const char *buffer, unsigned int length, const char **virname, const struct cl_node *root, unsigned short ftype)
{
int ret, *partcnt;
unsigned long int *partoff;
if((partcnt = (int *) cli_calloc(root->ac_partsigs + 1, sizeof(int))) == NULL) {
cli_dbgmsg("cl_scanbuff(): unable to cli_calloc(%d, %d)\n", root->ac_partsigs + 1, sizeof(int));
return CL_EMEM;
}
if((partoff = (unsigned long int *) cli_calloc(root->ac_partsigs + 1, sizeof(unsigned long int))) == NULL) {
cli_dbgmsg("cl_scanbuff(): unable to cli_calloc(%d, %d)\n", root->ac_partsigs + 1, sizeof(unsigned long int));
free(partcnt);
return CL_EMEM;
}
if((ret = cli_bm_scanbuff(buffer, length, virname, root, 0, ftype, -1)) != CL_VIRUS)
ret = cli_ac_scanbuff(buffer, length, virname, root, partcnt, 0, 0, partoff, ftype, -1);
free(partcnt);
free(partoff);
return ret;
}
int cl_scanbuff(const char *buffer, unsigned int length, const char **virname, const struct cl_node *root)
{
return cli_scanbuff(buffer, length, virname, root, 0);
}
static struct cli_md5_node *cli_vermd5(const unsigned char *md5, const struct cl_node *root)
{
struct cli_md5_node *pt;
if(!(pt = root->md5_hlist[md5[0] & 0xff]))
return NULL;
while(pt) {
if(!memcmp(pt->md5, md5, 16))
return pt;
pt = pt->next;
}
return NULL;
}
static long int cli_caloff(const char *offstr, int fd)
{
struct cli_pe_info peinfo;
long int offset = -1;
int n;
if(isdigit(offstr[0])) {
return atoi(offstr);
} if(!strncmp(offstr, "EP+", 3)) {
if((n = lseek(fd, 0, SEEK_CUR)) == -1) {
cli_dbgmsg("Invalid descriptor\n");
return -1;
}
lseek(fd, 0, SEEK_SET);
if(cli_peheader(fd, &peinfo)) {
lseek(fd, n, SEEK_SET);
return -1;
}
free(peinfo.section);
lseek(fd, n, SEEK_SET);
return peinfo.ep + atoi(offstr + 3);
} else if(offstr[0] == 'S') {
if((n = lseek(fd, 0, SEEK_CUR)) == -1) {
cli_dbgmsg("Invalid descriptor\n");
return -1;
}
lseek(fd, 0, SEEK_SET);
if(cli_peheader(fd, &peinfo)) {
lseek(fd, n, SEEK_SET);
return -1;
}
lseek(fd, n, SEEK_SET);
if(!strncmp(offstr, "SL", 2)) {
if(sscanf(offstr, "SL+%ld", &offset) != 1) {
free(peinfo.section);
return -1;
}
offset += peinfo.section[peinfo.nsections - 1].raw;
} else {
if(sscanf(offstr, "S%d+%ld", &n, &offset) != 2) {
free(peinfo.section);
return -1;
}
if(n >= peinfo.nsections) {
free(peinfo.section);
return -1;
}
offset += peinfo.section[n].raw;
}
free(peinfo.section);
return offset;
} else if(!strncmp(offstr, "EOF-", 4)) {
struct stat sb;
if(fstat(fd, &sb) == -1)
return -1;
return sb.st_size - atoi(offstr + 4);
}
return -1;
}
int cli_checkfp(int fd, const struct cl_node *root)
{
struct cli_md5_node *md5_node;
char *digest;
if(root->md5_hlist) {
if(!(digest = cli_md5digest(fd))) {
cli_errmsg("cli_checkfp(): Can't generate MD5 checksum\n");
return 0;
}
if((md5_node = cli_vermd5(digest, root)) && md5_node->fp) {
struct stat sb;
if(fstat(fd, &sb))
return CL_EIO;
if((unsigned int) sb.st_size != md5_node->size) {
cli_warnmsg("Detected false positive MD5 match. Please report.\n");
} else {
cli_dbgmsg("Eliminated false positive match (fp sig: %s)\n", md5_node->virname);
free(digest);
return 1;
}
}
free(digest);
}
return 0;
}
int cli_validatesig(unsigned short target, unsigned short ftype, const char *offstr, unsigned long int fileoff, int desc, const char *virname)
{
if(target) {
if(target >= TARGET_TABLE_SIZE) {
cli_errmsg("Bad target in signature (%s)\n", virname);
return 0;
} else {
if(targettab[target] != ftype) {
cli_dbgmsg("Type: %d, expected: %d (%s)\n", ftype, targettab[target], virname);
return 0;
}
}
}
if(offstr && desc != -1) {
long int off = cli_caloff(offstr, desc);
if(off == -1) {
cli_dbgmsg("Bad offset in signature (%s)\n", virname);
return 0;
}
if(fileoff != (unsigned long int) off) {
cli_dbgmsg("Virus offset: %d, expected: %d (%s)\n", fileoff, off, virname);
return 0;
}
}
return 1;
}
int cli_scandesc(int desc, const char **virname, long int *scanned, const struct cl_node *root, short otfrec, unsigned short ftype)
{
char *buffer, *buff, *endbl, *pt;
int bytes, buffsize, length, ret, *partcnt, type = CL_CLEAN;
unsigned long int *partoff, offset = 0;
MD5_CTX ctx;
unsigned char digest[16];
struct cli_md5_node *md5_node;
if(!root) {
cli_errmsg("cli_scandesc: root == NULL\n");
return CL_ENULLARG;
}
/* prepare the buffer */
buffsize = root->maxpatlen + SCANBUFF;
if(!(buffer = (char *) cli_calloc(buffsize, sizeof(char)))) {
cli_dbgmsg("cli_scandesc(): unable to cli_calloc(%d)\n", buffsize);
return CL_EMEM;
}
if((partcnt = (int *) cli_calloc(root->ac_partsigs + 1, sizeof(int))) == NULL) {
cli_dbgmsg("cli_scandesc(): unable to cli_calloc(%d, %d)\n", root->ac_partsigs + 1, sizeof(int));
free(buffer);
return CL_EMEM;
}
if((partoff = (unsigned long int *) cli_calloc(root->ac_partsigs + 1, sizeof(unsigned long int))) == NULL) {
cli_dbgmsg("cli_scandesc(): unable to cli_calloc(%d, %d)\n", root->ac_partsigs + 1, sizeof(unsigned long int));
free(buffer);
free(partcnt);
return CL_EMEM;
}
if(root->md5_hlist)
MD5_Init(&ctx);
buff = buffer;
buff += root->maxpatlen; /* pointer to read data block */
endbl = buff + SCANBUFF - root->maxpatlen; /* pointer to the last block
* length of root->maxpatlen
*/
pt = buff;
length = SCANBUFF;
while((bytes = read(desc, buff, SCANBUFF)) > 0) {
if(scanned)
*scanned += bytes / CL_COUNT_PRECISION;
if(bytes < SCANBUFF)
length -= SCANBUFF - bytes;
if(cli_bm_scanbuff(pt, length, virname, root, offset, ftype, desc) == CL_VIRUS ||
(ret = cli_ac_scanbuff(pt, length, virname, root, partcnt, otfrec, offset, partoff, ftype, desc)) == CL_VIRUS) {
free(buffer);
free(partcnt);
free(partoff);
lseek(desc, 0, SEEK_SET);
if(cli_checkfp(desc, root))
return CL_CLEAN;
else
return CL_VIRUS;
} else if(otfrec && ret >= CL_TYPENO) {
if(ret >= type)
type = ret;
}
if(bytes == SCANBUFF) {
memmove(buffer, endbl, root->maxpatlen);
if(pt == buffer) {
offset += SCANBUFF;
} else {
offset += SCANBUFF - root->maxpatlen;
pt = buffer;
length = buffsize;
}
}
if(root->md5_hlist)
MD5_Update(&ctx, buff, bytes);
}
free(buffer);
free(partcnt);
free(partoff);
if(root->md5_hlist) {
MD5_Final(digest, &ctx);
if(cli_debug_flag) {
char md5str[33];
int i;
pt = md5str;
for(i = 0; i < 16; i++) {
sprintf(pt, "%02x", digest[i]);
pt += 2;
}
md5str[32] = 0;
cli_dbgmsg("Calculated MD5 checksum: %s\n", md5str);
}
if((md5_node = cli_vermd5(digest, root)) && !md5_node->fp) {
struct stat sb;
if(fstat(desc, &sb))
return CL_EIO;
if((unsigned int) sb.st_size != md5_node->size) {
cli_warnmsg("Detected false positive MD5 match. Please report.\n");
} else {
if(virname)
*virname = md5_node->virname;
return CL_VIRUS;
}
}
}
return otfrec ? type : CL_CLEAN;
}
int cl_build(struct cl_node *root)
{
return cli_ac_buildtrie(root);
}
struct cl_node *cl_dup(struct cl_node *root)
{
if(!root) {
cli_errmsg("cl_dup: root == NULL\n");
return NULL;
}
#ifdef CL_THREAD_SAFE
pthread_mutex_lock(&cli_ref_mutex);
#endif
root->refcount++;
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&cli_ref_mutex);
#endif
return root;
}
void cl_free(struct cl_node *root)
{
int i;
struct cli_md5_node *md5pt, *md5h;
struct cli_meta_node *metapt, *metah;
if(!root) {
cli_errmsg("cl_free: root == NULL\n");
return;
}
#ifdef CL_THREAD_SAFE
pthread_mutex_lock(&cli_ref_mutex);
#endif
root->refcount--;
if (root->refcount) {
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&cli_ref_mutex);
#endif
return;
}
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&cli_ref_mutex);
#endif
cli_ac_free(root);
cli_bm_free(root);
if(root->md5_hlist) {
for(i = 0; i < 256; i++) {
md5pt = root->md5_hlist[i];
while(md5pt) {
md5h = md5pt;
md5pt = md5pt->next;
free(md5h->md5);
free(md5h->virname);
if(md5h->viralias)
free(md5h->viralias);
free(md5h);
}
}
free(root->md5_hlist);
}
metapt = root->zip_mlist;
while(metapt) {
metah = metapt;
metapt = metapt->next;
free(metah->virname);
if(metah->filename)
free(metah->filename);
free(metah);
}
metapt = root->rar_mlist;
while(metapt) {
metah = metapt;
metapt = metapt->next;
free(metah->virname);
if(metah->filename)
free(metah->filename);
free(metah);
}
free(root);
}
int cl_buildtrie(struct cl_node *root) /* for backward compatibility */
{
return cl_build(root);
}
void cl_freetrie(struct cl_node *root) /* for backward compatibility */
{
cl_free(root);
}