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