ClamAV is an open source (GPLv2) anti-virus toolkit.
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clamav/clamav-devel/libclamav/scanners.c

729 lines
19 KiB

/*
* Copyright (C) 2002, 2003 Tomasz Kojm <zolw@konarski.edu.pl>
*
* 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.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#ifdef CL_THREAD_SAFE
# include <pthread.h>
pthread_mutex_t cli_scanrar_mutex = PTHREAD_MUTEX_INITIALIZER;
int cli_scanrar_inuse = 0;
//pthread_mutex_t cli_mbox_mutex = PTHREAD_MUTEX_INITIALIZER;
//int cli_mbox_inuse = 0;
#endif
#include "clamav.h"
#include "others.h"
#include "matcher.h"
#include "unrarlib.h"
#ifdef HAVE_ZLIB_H
#include <zlib.h>
#include <zzip.h>
#endif
#ifdef HAVE_BZLIB_H
#include <bzlib.h>
#endif
#define SCAN_ARCHIVE (options & CL_ARCHIVE)
#define SCAN_MAIL (options & CL_MAIL)
#define DISABLE_RAR (options & CL_DISABLERAR)
#define MAGIC_BUFFER_SIZE 14
#define RAR_MAGIC_STR "Rar!"
#define ZIP_MAGIC_STR "PK\003\004"
#define GZIP_MAGIC_STR "\037\213"
#define MAIL_MAGIC_STR "From "
#define RAWMAIL_MAGIC_STR "Received: "
#define MAILDIR_MAGIC_STR "Return-Path: "
#define DELIVERED_MAGIC_STR "Delivered-To: "
#define BZIP_MAGIC_STR "BZh"
#define ZIPOSDET 50 /* FIXME: Make it user definable */
int cli_magic_scandesc(int desc, char **virname, long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options, int *reclev);
int cli_scandesc(int desc, char **virname, long int *scanned, const struct
cl_node *root)
{
char *buffer, *buff, *endbl, *pt;
int bytes, buffsize, length;
/* prepare the buffer */
buffsize = root->maxpatlen + SCANBUFF;
if(!(buffer = (char *) cli_calloc(buffsize, sizeof(char))))
return CL_EMEM;
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 != NULL)
*scanned += bytes / CL_COUNT_PRECISION;
if(bytes < SCANBUFF)
length -= SCANBUFF - bytes;
if(cl_scanbuff(pt, length, virname, root) == CL_VIRUS) {
free(buffer);
return CL_VIRUS;
}
if(bytes == SCANBUFF)
memmove(buffer, endbl, root->maxpatlen);
pt = buffer;
length=buffsize;
}
free(buffer);
return CL_CLEAN;
}
#ifdef CL_THREAD_SAFE
void cli_unlock_mutex(void *mtx)
{
cli_dbgmsg("Pthread cancelled. Unlocking mutex.\n");
pthread_mutex_unlock(mtx);
}
#endif
int cli_scanrar(int desc, char **virname, long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options, int *reclev)
{
FILE *tmp = NULL;
int files = 0, fd, ret = CL_CLEAN;
ArchiveList_struct *rarlist = NULL;
char *rar_data_ptr;
unsigned long rar_data_size;
cli_dbgmsg("Starting scanrar()\n");
#ifdef CL_THREAD_SAFE
pthread_cleanup_push(cli_unlock_mutex, &cli_scanrar_mutex);
pthread_mutex_lock(&cli_scanrar_mutex);
cli_scanrar_inuse = 1;
#endif
if(!urarlib_list(desc, (ArchiveList_struct *) &rarlist)) {
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&cli_scanrar_mutex);
cli_scanrar_inuse = 0;
#endif
return CL_ERAR;
}
while(rarlist) {
if(limits) {
if(limits->maxfilesize && (rarlist->item.UnpSize > limits->maxfilesize)) {
cli_dbgmsg("RAR->%s: Size exceeded (%d, max: %d)\n", rarlist->item.Name, rarlist->item.UnpSize, limits->maxfilesize);
rarlist = rarlist->next;
files++;
ret = CL_EMAXSIZE;
continue;
}
if(limits->maxfiles && (files > limits->maxfiles)) {
cli_dbgmsg("RAR: Files limit reached (max: %d)\n", limits->maxfiles);
ret = CL_EMAXFILES;
break;
}
}
if((tmp = tmpfile()) == NULL) {
cli_dbgmsg("RAR -> Can't generate tmpfile().\n");
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&cli_scanrar_mutex);
cli_scanrar_inuse = 0;
#endif
return CL_ETMPFILE;
}
fd = fileno(tmp);
if(urarlib_get(&rar_data_ptr, &rar_data_size, rarlist->item.Name, desc, "clam")) {
cli_dbgmsg("RAR -> Extracted: %s, size: %d\n", rarlist->item.Name, rar_data_size);
if(fwrite(rar_data_ptr, rar_data_size, 1, tmp) != 1) {
cli_dbgmsg("RAR -> Can't write() file.\n");
fclose(tmp);
tmp = NULL;
ret = CL_ERAR;
if(rar_data_ptr) {
free(rar_data_ptr);
rar_data_ptr = NULL;
}
break;
}
if(rar_data_ptr) {
free(rar_data_ptr);
rar_data_ptr = NULL;
}
if(fflush(tmp) != 0) {
cli_dbgmsg("fflush() failed: %s\n", strerror(errno));
fclose(tmp);
urarlib_freelist(rarlist);
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&cli_scanrar_mutex);
cli_scanrar_inuse = 0;
#endif
return CL_EFSYNC;
}
lseek(fd, 0, SEEK_SET);
if((ret = cli_magic_scandesc(fd, virname, scanned, root, limits, options, reclev)) == CL_VIRUS ) {
cli_dbgmsg("RAR -> Found %s virus.\n", *virname);
fclose(tmp);
urarlib_freelist(rarlist);
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&cli_scanrar_mutex);
cli_scanrar_inuse = 0;
#endif
return CL_VIRUS;
}
} else {
cli_dbgmsg("RAR -> Can't decompress file %s\n", rarlist->item.Name);
fclose(tmp);
ret = CL_ERAR; /* WinRAR 3.0 ? */
break;
}
fclose(tmp);
tmp = NULL;
rarlist = rarlist->next;
files++;
}
urarlib_freelist(rarlist);
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&cli_scanrar_mutex);
cli_scanrar_inuse = 0;
pthread_cleanup_pop(0);
#endif
return ret;
}
#ifdef HAVE_ZLIB_H
int cli_scanzip(int desc, char **virname, long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options, int *reclev)
{
ZZIP_DIR *zdir;
ZZIP_DIRENT zdirent;
ZZIP_FILE *zfp;
FILE *tmp = NULL;
char *buff;
int fd, bytes, files = 0, ret = CL_CLEAN, err;
struct stat source;
cli_dbgmsg("Starting scanzip()\n");
if((zdir = zzip_dir_fdopen(dup(desc), &err)) == NULL) {
cli_dbgmsg("Zip -> Not supported file format ?.\n");
cli_dbgmsg("zzip_dir_fdopen() return code: %d\n", err);
return CL_EZIP;
}
fstat(desc, &source);
if(!(buff = (char *) cli_malloc(FILEBUFF))) {
zzip_dir_close(zdir);
return CL_EMEM;
}
while(zzip_dir_read(zdir, &zdirent)) {
if(!zdirent.d_name || !strlen(zdirent.d_name)) { /* Mimail fix */
cli_dbgmsg("strlen(zdirent.d_name) == %d\n", strlen(zdirent.d_name));
*virname = "Seriously Broken Zip";
ret = CL_VIRUS;
break;
}
cli_dbgmsg("Zip -> %s, compressed: %d, normal: %d.\n", zdirent.d_name, zdirent.d_csize, zdirent.st_size);
if(source.st_size && (zdirent.st_size / source.st_size) >= ZIPOSDET) {
*virname = "Oversized Zip";
ret = CL_VIRUS;
break;
}
if(!zdirent.st_size) { /* omit directories and null files */
files++;
continue;
}
/* work-around for problematic zips (zziplib crashes with them) */
if(zdirent.d_csize < 0 || zdirent.st_size < 0) {
files++;
cli_dbgmsg("Zip -> Malformed archive detected.\n");
/* ret = CL_EMALFZIP; */
/* report it as a virus */
*virname = "Seriously Broken Zip";
ret = CL_VIRUS;
break;
}
if(limits) {
if(limits->maxfilesize && (zdirent.st_size > limits->maxfilesize)) {
cli_dbgmsg("Zip -> %s: Size exceeded (%d, max: %d)\n", zdirent.d_name, zdirent.st_size, limits->maxfilesize);
files++;
ret = CL_EMAXSIZE;
continue; /* this is not a bug */
}
if(limits->maxfiles && (files > limits->maxfiles)) {
cli_dbgmsg("Zip: Files limit reached (max: %d)\n", limits->maxfiles);
ret = CL_EMAXFILES;
break;
}
}
/* generate temporary file and get its descriptor */
if((tmp = tmpfile()) == NULL) {
cli_dbgmsg("Zip -> Can't generate tmpfile().\n");
ret = CL_ETMPFILE;
break;
}
if((zfp = zzip_file_open(zdir, zdirent.d_name, 0)) == NULL) {
cli_dbgmsg("Zip -> %s: Can't open file.\n", zdirent.d_name);
ret = CL_EZIP;
break;
}
while((bytes = zzip_file_read(zfp, buff, FILEBUFF)) > 0) {
if(fwrite(buff, bytes, 1, tmp)*bytes != bytes) {
cli_dbgmsg("Zip -> Can't fwrite() file: %s\n", strerror(errno));
zzip_file_close(zfp);
zzip_dir_close(zdir);
fclose(tmp);
free(buff);
return CL_EZIP;
}
}
zzip_file_close(zfp);
if(fflush(tmp) != 0) {
cli_errmsg("fflush() failed: %s\n", strerror(errno));
ret = CL_EFSYNC;
break;
}
fd = fileno(tmp);
lseek(fd, 0, SEEK_SET);
if((ret = cli_magic_scandesc(fd, virname, scanned, root, limits, options, reclev)) == CL_VIRUS ) {
cli_dbgmsg("Zip -> Found %s virus.\n", *virname);
ret = CL_VIRUS;
break;
} else if(ret == CL_EMALFZIP) {
/*
* The trick with detection of ZoD only works with higher (>= 5)
* recursion limit level.
*/
cli_dbgmsg("Zip -> Malformed Zip, scanning stopped.\n");
*virname = "Malformed Zip";
ret = CL_VIRUS;
break;
}
if (tmp) {
fclose(tmp);
tmp = NULL;
}
files++;
}
zzip_dir_close(zdir);
if (tmp) {
fclose(tmp);
tmp = NULL;
}
free(buff);
return ret;
}
int cli_scangzip(int desc, char **virname, long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options, int *reclev)
{
int fd, bytes, ret = CL_CLEAN;
long int size = 0;
char *buff;
FILE *tmp = NULL;
gzFile gd;
cli_dbgmsg("in cli_scangzip()\n");
if((gd = gzdopen(dup(desc), "rb")) == NULL) {
cli_dbgmsg("Can't gzdopen() descriptor %d.\n", desc);
return CL_EGZIP;
}
if((tmp = tmpfile()) == NULL) {
cli_dbgmsg("Can't generate tmpfile().\n");
gzclose(gd);
return CL_ETMPFILE;
}
fd = fileno(tmp);
if(!(buff = (char *) cli_malloc(FILEBUFF))) {
gzclose(gd);
return CL_EMEM;
}
while((bytes = gzread(gd, buff, FILEBUFF)) > 0) {
size += bytes;
if(limits)
if(limits->maxfilesize && (size + FILEBUFF > limits->maxfilesize)) {
cli_dbgmsg("Gzip->desc(%d): Size exceeded (stopped at %d, max: %d)\n", desc, size, limits->maxfilesize);
ret = CL_EMAXSIZE;
break;
}
if(write(fd, buff, bytes) != bytes) {
cli_dbgmsg("Gzip -> Can't write() file.\n");
fclose(tmp);
gzclose(gd);
free(buff);
return CL_EGZIP;
}
}
free(buff);
gzclose(gd);
if(fsync(fd) == -1) {
cli_dbgmsg("fsync() failed for descriptor %d\n", fd);
fclose(tmp);
return CL_EFSYNC;
}
lseek(fd, 0, SEEK_SET);
if((ret = cli_magic_scandesc(fd, virname, scanned, root, limits, options, reclev)) == CL_VIRUS ) {
cli_dbgmsg("Gzip -> Found %s virus.\n", *virname);
fclose(tmp);
return CL_VIRUS;
}
fclose(tmp);
return ret;
}
#endif
#ifdef HAVE_BZLIB_H
#ifdef NOBZ2PREFIX
#define BZ2_bzReadOpen bzReadOpen
#define BZ2_bzReadClose bzReadClose
#define BZ2_bzRead bzRead
#endif
int cli_scanbzip(int desc, char **virname, long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options, int *reclev)
{
int fd, bytes, ret = CL_CLEAN, bzerror = 0;
short memlim = 0;
long int size = 0;
char *buff;
FILE *fs, *tmp = NULL;
BZFILE *bfd;
if((fs = fdopen(desc, "rb")) == NULL) {
cli_errmsg("Can't fdopen() descriptor %d.\n", desc);
return CL_EBZIP;
}
if(limits)
if(limits->archivememlim)
memlim = 1;
if((bfd = BZ2_bzReadOpen(&bzerror, fs, memlim, 0, NULL, 0)) == NULL) {
cli_dbgmsg("Can't initialize bzip2 library (descriptor %d).\n", desc);
return CL_EBZIP;
}
if((tmp = tmpfile()) == NULL) {
cli_dbgmsg("Can't generate tmpfile().\n");
BZ2_bzReadClose(&bzerror, bfd);
return CL_ETMPFILE;
}
fd = fileno(tmp);
if(!(buff = (char *) cli_malloc(FILEBUFF)))
return CL_EMEM;
while((bytes = BZ2_bzRead(&bzerror, bfd, buff, FILEBUFF)) > 0) {
size += bytes;
if(limits)
if(limits->maxfilesize && (size + FILEBUFF > limits->maxfilesize)) {
cli_dbgmsg("Bzip2->desc(%d): Size exceeded (stopped at %d, max: %d)\n", desc, size, limits->maxfilesize);
ret = CL_EMAXSIZE;
break;
}
if(write(fd, buff, bytes) != bytes) {
cli_dbgmsg("Bzip2 -> Can't write() file.\n");
BZ2_bzReadClose(&bzerror, bfd);
fclose(tmp);
free(buff);
return CL_EGZIP;
}
}
free(buff);
BZ2_bzReadClose(&bzerror, bfd);
if(fsync(fd) == -1) {
cli_dbgmsg("fsync() failed for descriptor %d\n", fd);
fclose(tmp);
return CL_EFSYNC;
}
lseek(fd, 0, SEEK_SET);
if((ret = cli_magic_scandesc(fd, virname, scanned, root, limits, options, reclev)) == CL_VIRUS ) {
cli_dbgmsg("Bzip2 -> Found %s virus.\n", *virname);
fclose(tmp);
return CL_VIRUS;
}
fclose(tmp);
return ret;
}
#endif
int cli_scandir(char *dirname, char **virname, long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options, int *reclev)
{
DIR *dd;
struct dirent *dent;
struct stat statbuf;
char *fname;
if((dd = opendir(dirname)) != NULL) {
while((dent = readdir(dd))) {
if(dent->d_ino) {
if(strcmp(dent->d_name, ".") && strcmp(dent->d_name, "..")) {
/* build the full name */
fname = cli_calloc(strlen(dirname) + strlen(dent->d_name) + 2, sizeof(char));
sprintf(fname, "%s/%s", dirname, dent->d_name);
/* stat the file */
if(lstat(fname, &statbuf) != -1) {
if(S_ISDIR(statbuf.st_mode) && !S_ISLNK(statbuf.st_mode))
cli_scandir(dirname, virname, scanned, root, limits, options, reclev);
else
if(S_ISREG(statbuf.st_mode))
if(cl_scanfile(fname, virname, scanned, root, limits, options) == CL_VIRUS) {
free(fname);
closedir(dd);
return CL_VIRUS;
}
}
free(fname);
}
}
}
} else {
cli_errmsg("ScanDir -> Can't open directory %s.\n", dirname);
return CL_EOPEN;
}
closedir(dd);
return 0;
}
int cli_scanmail(int desc, char **virname, long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options, int *reclev)
{
const char *tmpdir;
char *dir;
int ret;
cli_dbgmsg("Starting scanmail()\n");
/*
#ifdef CL_THREAD_SAFE
pthread_cleanup_push(cli_unlock_mutex, &cli_mbox_mutex);
pthread_mutex_lock(&cli_mbox_mutex);
cli_mbox_inuse = 1;
#endif
*/
tmpdir = getenv("TMPDIR");
if(tmpdir == NULL)
#ifdef P_tmpdir
tmpdir = P_tmpdir;
#else
tmpdir = "/tmp";
#endif
/* generate the temporary directory */
dir = cl_gentemp(tmpdir);
if(mkdir(dir, 0700)) {
cli_errmsg("ScanMail -> Can't create temporary directory %s\n", dir);
/*
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&cli_mbox_mutex);
cli_mbox_inuse = 0;
#endif
*/
return CL_ETMPDIR;
}
/*
* Extract the attachments into the temporary directory
*/
ret = cl_mbox(dir, desc);
/* FIXME: check mbox return code */
ret = cli_scandir(dir, virname, scanned, root, limits, options, reclev);
cli_rmdirs(dir);
free(dir);
/*
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&cli_mbox_mutex);
cli_mbox_inuse = 0;
pthread_cleanup_pop(0);
#endif
*/
return ret;
}
int cli_magic_scandesc(int desc, char **virname, long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options, int *reclev)
{
char magic[MAGIC_BUFFER_SIZE+1];
int ret = CL_CLEAN;
int bread = 0;
if(!root) {
cli_errmsg("root == NULL\n");
return -1;
}
if(SCAN_ARCHIVE || SCAN_MAIL) {
/* Need to examine file type */
if(SCAN_ARCHIVE && limits && limits->maxreclevel)
if(*reclev > limits->maxreclevel)
return CL_EMAXREC;
(*reclev)++;
lseek(desc, 0, SEEK_SET);
bread = read(desc, magic, MAGIC_BUFFER_SIZE);
magic[MAGIC_BUFFER_SIZE] = '\0'; /* terminate magic string properly */
lseek(desc, 0, SEEK_SET);
if (bread != MAGIC_BUFFER_SIZE) {
/* short read: No need to do magic */
(*reclev)--;
return ret;
}
#ifdef CL_THREAD_SAFE
/* this check protects against recursive deadlock */
if(!DISABLE_RAR && SCAN_ARCHIVE && !cli_scanrar_inuse && !strncmp(magic, RAR_MAGIC_STR, strlen(RAR_MAGIC_STR))) {
ret = cli_scanrar(desc, virname, scanned, root, limits, options, reclev);
}
#else
if(!DISABLE_RAR && SCAN_ARCHIVE && !strncmp(magic, RAR_MAGIC_STR, strlen(RAR_MAGIC_STR))) {
ret = cli_scanrar(desc, virname, scanned, root, limits, options, reclev);
}
#endif
#ifdef HAVE_ZLIB_H
else if(SCAN_ARCHIVE && !strncmp(magic, ZIP_MAGIC_STR, strlen(ZIP_MAGIC_STR))) {
ret = cli_scanzip(desc, virname, scanned, root, limits, options, reclev);
} else if(SCAN_ARCHIVE && !strncmp(magic, GZIP_MAGIC_STR, strlen(GZIP_MAGIC_STR))) {
ret = cli_scangzip(desc, virname, scanned, root, limits, options, reclev);
}
#endif
#ifdef HAVE_BZLIB_H
else if(SCAN_ARCHIVE && !strncmp(magic, BZIP_MAGIC_STR, strlen(BZIP_MAGIC_STR))) {
ret = cli_scanbzip(desc, virname, scanned, root, limits, options, reclev);
}
#endif
else if(SCAN_MAIL && !strncmp(magic, MAIL_MAGIC_STR, strlen(MAIL_MAGIC_STR))) {
ret = cli_scanmail(desc, virname, scanned, root, limits, options, reclev);
}
else if(SCAN_MAIL && !strncmp(magic, RAWMAIL_MAGIC_STR, strlen(RAWMAIL_MAGIC_STR))) {
ret = cli_scanmail(desc, virname, scanned, root, limits, options, reclev);
} else if(SCAN_MAIL && !strncmp(magic, MAILDIR_MAGIC_STR, strlen(MAILDIR_MAGIC_STR))) {
cli_dbgmsg("Recognized Maildir mail file.\n");
ret = cli_scanmail(desc, virname, scanned, root, limits, options, reclev);
} else if(SCAN_MAIL && !strncmp(magic, DELIVERED_MAGIC_STR, strlen(DELIVERED_MAGIC_STR))) {
cli_dbgmsg("Recognized (Delivered-To) mail file.\n");
ret = cli_scanmail(desc, virname, scanned, root, limits, options, reclev);
}
(*reclev)--;
}
if(ret != CL_VIRUS) /* scan the raw file */
lseek(desc, 0, SEEK_SET); /* If archive scan didn't rewind desc */
if(cli_scandesc(desc, virname, scanned, root) == CL_VIRUS) {
cli_dbgmsg("%s virus found in descriptor %d.\n", *virname, desc);
return CL_VIRUS;
}
return ret;
}
int cl_scandesc(int desc, char **virname, unsigned long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options)
{
int reclev = 0;
return cli_magic_scandesc(desc, virname, scanned, root, limits, options, &reclev);
}
int cl_scanfile(const char *filename, char **virname, unsigned long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options)
{
int fd, ret;
if((fd = open(filename, O_RDONLY)) == -1)
return CL_EOPEN;
cli_dbgmsg("Scanning %s\n", filename);
ret = cl_scandesc(fd, virname, scanned, root, limits, options);
close(fd);
return ret;
}