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/* |
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* Copyright (C) 2002 - 2004 Tomasz Kojm <tkojm@clamav.net> |
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*
* 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.
*/
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#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
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#include <string.h> |
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#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h> |
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#include "clamav.h"
#include "others.h" |
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#include "matcher-ac.h"
#include "matcher-bm.h"
#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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|
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#define MD5_BLOCKSIZE 4096 |
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|
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#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 }; |
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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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{
int ret, *partcnt;
unsigned long int *partoff; |
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|
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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; |
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}
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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); |
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return CL_EMEM; |
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} |
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|
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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); |
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free(partcnt);
free(partoff);
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)
{
return cli_scanbuff(buffer, length, virname, root, 0);
}
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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) {
if(!memcmp(pt->md5, md5, 16))
return pt; |
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|
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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)
{
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); |
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if(cli_peheader(fd, &peinfo)) {
lseek(fd, n, SEEK_SET); |
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return -1; |
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} |
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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); |
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if(cli_peheader(fd, &peinfo)) {
lseek(fd, n, SEEK_SET); |
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return -1; |
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} |
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lseek(fd, n, SEEK_SET);
if(sscanf(offstr, "S%d+%ld", &n, &offset) != 2)
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_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(ftype) {
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 != off) {
cli_dbgmsg("Virus offset: %d, expected: %d (%s)\n", fileoff, off, virname);
return 0;
}
}
return 1;
}
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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) |
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{ |
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char *buffer, *buff, *endbl, *pt;
int bytes, buffsize, length, ret, *partcnt, type = CL_CLEAN;
unsigned long int *partoff, offset = 0; |
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struct MD5Context ctx;
unsigned char digest[16]; |
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struct cli_md5_node *md5_node; |
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|
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if(!root) {
cli_errmsg("cli_scandesc: root == NULL\n");
return CL_ENULLARG; |
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}
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/* prepare the buffer */
buffsize = root->maxpatlen + SCANBUFF;
if(!(buffer = (char *) cli_calloc(buffsize, sizeof(char)))) {
cli_dbgmsg("cli_scandesc(): unable to cli_malloc(%d)\n", buffsize);
return CL_EMEM;
} |
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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;
} |
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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);
free(partcnt);
return CL_EMEM;
} |
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if(root->md5_hlist) |
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MD5Init(&ctx); |
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buff = buffer;
buff += root->maxpatlen; /* pointer to read data block */
endbl = buff + SCANBUFF - root->maxpatlen; /* pointer to the last block
* length of root->maxpatlen
*/ |
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pt = buff; |
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length = SCANBUFF;
while((bytes = read(desc, buff, SCANBUFF)) > 0) { |
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if(scanned)
*scanned += bytes / CL_COUNT_PRECISION; |
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if(bytes < SCANBUFF)
length -= SCANBUFF - bytes; |
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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) { |
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free(buffer);
free(partcnt);
free(partoff);
return CL_VIRUS; |
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|
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} else if(otfrec && ret >= CL_TYPENO) { |
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if(ret >= type)
type = ret;
} |
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if(bytes == SCANBUFF) {
memmove(buffer, endbl, root->maxpatlen);
offset += bytes - root->maxpatlen;
} |
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pt = buffer;
length = buffsize; |
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if(root->md5_hlist)
MD5Update(&ctx, buff, bytes); |
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} |
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free(buffer);
free(partcnt);
free(partoff); |
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if(root->md5_hlist) { |
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MD5Final(digest, &ctx); |
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if((md5_node = cli_vermd5(digest, root))) { |
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struct stat sb;
if(fstat(desc, &sb))
return CL_EIO;
if(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;
} |
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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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void cl_free(struct cl_node *root)
{
int i;
struct cli_md5_node *pt, *h; |
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|
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if(!root) {
cli_errmsg("cl_free: root == NULL\n");
return; |
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}
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cli_ac_free(root);
cli_bm_free(root); |
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if(root->md5_hlist) {
for(i = 0; i < 256; i++) { |
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pt = root->md5_hlist[i];
while(pt) { |
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h = pt; |
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pt = pt->next; |
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free(h->md5);
free(h->virname);
if(h->viralias)
free(h->viralias); |
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free(h); |
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}
} |
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free(root->md5_hlist); |
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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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void cl_freetrie(struct cl_node *root) /* for backward compatibility */
{ |
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cl_free(root); |
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} |