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448 lines
13 KiB
448 lines
13 KiB
/*
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* Copyright (C) 2015 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
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* Copyright (C) 2011 Sourcefire, Inc.
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*
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* Authors: Tomasz Kojm, Mickey Sola
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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 version 2 as
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* published by the Free Software Foundation.
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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., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, 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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#if defined(FANOTIFY)
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <pthread.h>
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#include <string.h>
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#include <errno.h>
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#include <time.h>
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#include <sys/fanotify.h>
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#include "libclamav/clamav.h"
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#include "libclamav/scanners.h"
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#include "shared/optparser.h"
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#include "shared/output.h"
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#include "onaccess_others.h"
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#include "server.h"
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#include "onaccess_fan.h"
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#include "onaccess_hash.h"
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#include "onaccess_ddd.h"
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static pthread_t ddd_pid;
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static int onas_fan_fd;
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static void onas_fan_exit(int sig)
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{
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logg("*ScanOnAccess: onas_fan_exit(), signal %d\n", sig);
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close(onas_fan_fd);
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if (ddd_pid > 0) {
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pthread_kill(ddd_pid, SIGUSR1);
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pthread_join(ddd_pid, NULL);
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}
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pthread_exit(NULL);
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logg("ScanOnAccess: stopped\n");
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}
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static int onas_fan_scanfile(int fan_fd, const char *fname, struct fanotify_event_metadata *fmd, int scan, int extinfo, struct thrarg *tharg)
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{
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struct fanotify_response res;
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const char *virname = NULL;
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int ret = 0;
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res.fd = fmd->fd;
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res.response = FAN_ALLOW;
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if (scan) {
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if (onas_scan(fname, fmd->fd, &virname, tharg->engine, tharg->options, extinfo) == CL_VIRUS) {
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/* TODO : FIXME? virusaction forks. This could be extraordinarily problematic, lead to deadlocks,
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* or at the very least lead to extreme memory consumption. Leaving disabled for now.*/
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//virusaction(fname, virname, tharg->opts);
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res.response = FAN_DENY;
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}
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}
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if(fmd->mask & FAN_ALL_PERM_EVENTS) {
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ret = write(fan_fd, &res, sizeof(res));
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if(ret == -1)
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logg("!ScanOnAccess: Internal error (can't write to fanotify)\n");
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}
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return ret;
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}
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void *onas_fan_th(void *arg)
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{
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struct thrarg *tharg = (struct thrarg *) arg;
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sigset_t sigset;
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struct sigaction act;
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const struct optstruct *pt;
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short int scan;
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unsigned int sizelimit = 0, extinfo;
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STATBUF sb;
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uint64_t fan_mask = FAN_EVENT_ON_CHILD | FAN_CLOSE;
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fd_set rfds;
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char buf[4096];
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ssize_t bread;
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struct fanotify_event_metadata *fmd;
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char fname[1024];
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int ret, len, check;
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char err[128];
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pthread_attr_t ddd_attr;
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struct ddd_thrarg *ddd_tharg = NULL;
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ddd_pid = 0;
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/* ignore all signals except SIGUSR1 */
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sigfillset(&sigset);
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sigdelset(&sigset, SIGUSR1);
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/* The behavior of a process is undefined after it ignores a
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* SIGFPE, SIGILL, SIGSEGV, or SIGBUS signal */
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sigdelset(&sigset, SIGFPE);
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sigdelset(&sigset, SIGILL);
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sigdelset(&sigset, SIGSEGV);
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#ifdef SIGBUS
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sigdelset(&sigset, SIGBUS);
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#endif
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pthread_sigmask(SIG_SETMASK, &sigset, NULL);
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memset(&act, 0, sizeof(struct sigaction));
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act.sa_handler = onas_fan_exit;
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sigfillset(&(act.sa_mask));
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sigaction(SIGUSR1, &act, NULL);
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sigaction(SIGSEGV, &act, NULL);
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/* Initialize fanotify */
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onas_fan_fd = fanotify_init(FAN_CLASS_CONTENT | FAN_UNLIMITED_QUEUE | FAN_UNLIMITED_MARKS, O_LARGEFILE | O_RDONLY);
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if(onas_fan_fd < 0) {
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logg("!ScanOnAccess: fanotify_init failed: %s\n", cli_strerror(errno, err, sizeof(err)));
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if(errno == EPERM)
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logg("ScanOnAccess: clamd must be started by root\n");
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return NULL;
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}
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if (!tharg) {
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logg("!Unable to start on-access scanner. Bad thread args.\n");
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return NULL;
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}
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if (optget(tharg->opts, "OnAccessPrevention")->enabled && !optget(tharg->opts, "OnAccessMountPath")->enabled) {
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logg("ScanOnAccess: preventing access attempts on malicious files.\n");
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fan_mask |= FAN_ACCESS_PERM | FAN_OPEN_PERM;
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} else {
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logg("ScanOnAccess: notifying only for access attempts.\n");
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fan_mask |= FAN_ACCESS | FAN_OPEN;
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}
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if ((pt = optget(tharg->opts, "OnAccessMountPath"))->enabled) {
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while(pt) {
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if(fanotify_mark(onas_fan_fd, FAN_MARK_ADD | FAN_MARK_MOUNT, fan_mask, onas_fan_fd, pt->strarg) != 0) {
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logg("!ScanOnAccess: Can't include mountpoint '%s'\n", pt->strarg);
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return NULL;
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} else
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logg("ScanOnAccess: Protecting '%s' and rest of mount.\n", pt->strarg);
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pt = (struct optstruct *) pt->nextarg;
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}
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} else if (!optget(tharg->opts, "OnAccessDisableDDD")->enabled) {
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int thread_started = 1;
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do {
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if(pthread_attr_init(&ddd_attr)) break;
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pthread_attr_setdetachstate(&ddd_attr, PTHREAD_CREATE_JOINABLE);
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/* Allocate memory for arguments. Thread is responsible for freeing it. */
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if (!(ddd_tharg = (struct ddd_thrarg *) calloc(sizeof(struct ddd_thrarg), 1))) break;
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if (!(ddd_tharg->options = (struct cl_scan_options *) calloc(sizeof(struct cl_scan_options), 1))) break;
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(void) memcpy(ddd_tharg->options, tharg->options, sizeof(struct cl_scan_options));
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ddd_tharg->fan_fd = onas_fan_fd;
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ddd_tharg->fan_mask = fan_mask;
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ddd_tharg->opts = tharg->opts;
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ddd_tharg->engine = tharg->engine;
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thread_started = pthread_create(&ddd_pid, &ddd_attr, onas_ddd_th, ddd_tharg);
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} while(0);
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if (0 != thread_started) {
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/* Failed to create thread. Free anything we may have allocated. */
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logg("!Unable to start dynamic directory determination.\n");
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if (NULL != ddd_tharg) {
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if (NULL != ddd_tharg->options) {
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free(ddd_tharg->options);
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ddd_tharg->options = NULL;
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}
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free(ddd_tharg);
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ddd_tharg = NULL;
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}
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}
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} else {
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if((pt = optget(tharg->opts, "OnAccessIncludePath"))->enabled) {
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while(pt) {
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if(fanotify_mark(onas_fan_fd, FAN_MARK_ADD, fan_mask, onas_fan_fd, pt->strarg) != 0) {
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logg("!ScanOnAccess: Can't include path '%s'\n", pt->strarg);
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return NULL;
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} else
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logg("ScanOnAccess: Protecting directory '%s'\n", pt->strarg);
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pt = (struct optstruct *) pt->nextarg;
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}
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} else {
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logg("!ScanOnAccess: Please specify at least one path with OnAccessIncludePath\n");
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return NULL;
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}
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}
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/* Load other options. */
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sizelimit = optget(tharg->opts, "OnAccessMaxFileSize")->numarg;
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if(sizelimit)
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logg("ScanOnAccess: Max file size limited to %u bytes\n", sizelimit);
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else
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logg("ScanOnAccess: File size limit disabled\n");
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extinfo = optget(tharg->opts, "ExtendedDetectionInfo")->enabled;
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FD_ZERO(&rfds);
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FD_SET(onas_fan_fd, &rfds);
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do {
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if (reload) sleep(1);
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ret = select(onas_fan_fd + 1, &rfds, NULL, NULL, NULL);
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} while((ret == -1 && errno == EINTR) || reload);
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time_t start = time(NULL) - 30;
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while(((bread = read(onas_fan_fd, buf, sizeof(buf))) > 0) || errno == EOVERFLOW) {
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if (errno == EOVERFLOW) {
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if (time(NULL) - start >= 30) {
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logg("!ScanOnAccess: Internal error (failed to read data) ... %s\n", strerror(errno));
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logg("!ScanOnAccess: File too large for fanotify ... recovering and continuing scans...\n");
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start = time(NULL);
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}
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errno = 0;
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continue;
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}
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fmd = (struct fanotify_event_metadata *) buf;
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while(FAN_EVENT_OK(fmd, bread)) {
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scan = 1;
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if(fmd->fd >= 0) {
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sprintf(fname, "/proc/self/fd/%d", fmd->fd);
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len = readlink(fname, fname, sizeof(fname) - 1);
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if(len == -1) {
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close(fmd->fd);
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logg("!ScanOnAccess: Internal error (readlink() failed)\n");
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return NULL;
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}
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fname[len] = 0;
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if((check = onas_fan_checkowner(fmd->pid, tharg->opts))) {
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scan = 0;
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/* TODO: Re-enable OnAccessExtraScanning once the thread resource consumption issue is resolved. */
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#if 0
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if ((check != CHK_SELF) || !(optget(tharg->opts, "OnAccessExtraScanning")->enabled)) {
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#else
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if (check != CHK_SELF) {
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#endif
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logg("*ScanOnAccess: %s skipped (excluded UID)\n", fname);
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}
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}
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if(sizelimit) {
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if(FSTAT(fmd->fd, &sb) != 0 || sb.st_size > sizelimit) {
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scan = 0;
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/* logg("*ScanOnAccess: %s skipped (size > %d)\n", fname, sizelimit); */
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}
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}
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if(onas_fan_scanfile(onas_fan_fd, fname, fmd, scan, extinfo, tharg) == -1) {
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close(fmd->fd);
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return NULL;
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}
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if(close(fmd->fd) == -1) {
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printf("!ScanOnAccess: Internal error (close(%d) failed)\n", fmd->fd);
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close(fmd->fd);
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return NULL;
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}
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}
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fmd = FAN_EVENT_NEXT(fmd, bread);
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}
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do {
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if (reload) sleep(1);
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ret = select(onas_fan_fd + 1, &rfds, NULL, NULL, NULL);
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} while((ret == -1 && errno == EINTR) || reload);
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}
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if(bread < 0)
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logg("!ScanOnAccess: Internal error (failed to read data) ... %s\n", strerror(errno));
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return NULL;
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}
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/* CLAMAUTH is deprecated */
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#elif defined(CLAMAUTH)
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/uio.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <pthread.h>
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#include <string.h>
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#include <errno.h>
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#include "libclamav/clamav.h"
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#include "libclamav/scanners.h"
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#include "shared/optparser.h"
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#include "shared/output.h"
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#include "server.h"
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#include "others.h"
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#include "scanner.h"
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#define SUPPORTED_PROTOCOL 2
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static int cauth_fd = -1;
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struct ClamAuthEvent {
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unsigned int action;
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char path[1024];
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unsigned int pid;
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};
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static void cauth_exit(int sig)
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{
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logg("*ScanOnAccess: cauth_exit(), signal %d\n", sig);
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if(cauth_fd > 0)
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close(cauth_fd);
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pthread_exit(NULL);
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logg("ScanOnAccess: stopped\n");
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}
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static int cauth_scanfile(const char *fname, int extinfo, struct thrarg *tharg)
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{
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struct cb_context context;
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const char *virname = NULL;
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int ret = 0, fd;
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context.filename = fname;
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context.virsize = 0;
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context.scandata = NULL;
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fd = open(fname, O_RDONLY);
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if(fd == -1)
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return -1;
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if(cl_scandesc_callback(fd, fname, &virname, NULL, tharg->engine, tharg->options, &context) == CL_VIRUS) {
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if(extinfo && context.virsize)
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logg("ScanOnAccess: %s: %s(%s:%llu) FOUND\n", fname, virname, context.virhash, context.virsize);
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else
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logg("ScanOnAccess: %s: %s FOUND\n", fname, virname);
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virusaction(fname, virname, tharg->opts);
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}
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close(fd);
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return ret;
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}
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void *onas_fan_th(void *arg)
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{
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struct thrarg *tharg = (struct thrarg *) arg;
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sigset_t sigset;
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struct sigaction act;
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int eventcnt = 1, extinfo;
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char err[128];
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struct ClamAuthEvent event;
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/* ignore all signals except SIGUSR1 */
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sigfillset(&sigset);
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sigdelset(&sigset, SIGUSR1);
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/* The behavior of a process is undefined after it ignores a
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* SIGFPE, SIGILL, SIGSEGV, or SIGBUS signal */
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sigdelset(&sigset, SIGFPE);
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sigdelset(&sigset, SIGILL);
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sigdelset(&sigset, SIGSEGV);
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#ifdef SIGBUS
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sigdelset(&sigset, SIGBUS);
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#endif
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pthread_sigmask(SIG_SETMASK, &sigset, NULL);
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memset(&act, 0, sizeof(struct sigaction));
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act.sa_handler = cauth_exit;
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sigfillset(&(act.sa_mask));
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sigaction(SIGUSR1, &act, NULL);
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sigaction(SIGSEGV, &act, NULL);
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extinfo = optget(tharg->opts, "ExtendedDetectionInfo")->enabled;
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cauth_fd = open("/dev/clamauth", O_RDONLY);
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if(cauth_fd == -1) {
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logg("!ScanOnAccess: Can't open /dev/clamauth\n");
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if(errno == ENOENT)
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logg("!ScanOnAccess: Please make sure ClamAuth.kext is loaded\n");
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else if(errno == EACCES)
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logg("!ScanOnAccess: This application requires root privileges\n");
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else
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logg("!ScanOnAccess: /dev/clamauth: %s\n", cli_strerror(errno, err, sizeof(err)));
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return NULL;
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}
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while(1) {
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if(read(cauth_fd, &event, sizeof(event)) > 0) {
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if(eventcnt == 1) {
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if(event.action != SUPPORTED_PROTOCOL) {
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logg("!ScanOnAccess: Protocol version mismatch (tool: %d, driver: %d)\n", SUPPORTED_PROTOCOL, event.action);
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close(cauth_fd);
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return NULL;
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}
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if(strncmp(event.path, "ClamAuth", 8)) {
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logg("!ScanOnAccess: Invalid version event\n");
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close(cauth_fd);
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return NULL;
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}
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logg("ScanOnAccess: Driver version: %s, protocol version: %d\n", &event.path[9], event.action);
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} else {
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cauth_scanfile(event.path, extinfo, tharg);
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}
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eventcnt++;
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} else {
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if(errno == ENODEV) {
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printf("^ScanOnAccess: ClamAuth module deactivated, terminating\n");
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close(cauth_fd);
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return NULL;
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}
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}
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usleep(200);
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}
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}
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#endif
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