/*
* Copyright (C) 2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
*
* Authors: Mickey Sola
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#if defined(FANOTIFY)
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <pthread.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <sys/fanotify.h>
#include "libclamav/clamav.h"
#include "libclamav/scanners.h"
#include "shared/optparser.h"
#include "shared/output.h"
#include "clamd/server.h"
#include "../inotif/hash.h"
#include "../inotif/inotif.h"
#include "../client/client.h"
#include "../scan/thread.h"
#include "../scan/queue.h"
#include "../misc/utils.h"
#include "fanotif.h"
extern pthread_t ddd_pid;
extern pthread_t scan_queue_pid;
static int onas_fan_fd;
cl_error_t onas_setup_fanotif(struct onas_context **ctx)
{
const struct optstruct *pt;
short int scan;
unsigned int sizelimit = 0, extinfo;
uint64_t fan_mask = FAN_EVENT_ON_CHILD;
pthread_attr_t ddd_attr;
struct ddd_thrarg *ddd_tharg = NULL;
ddd_pid = 0;
if (!ctx || !*ctx) {
logg("!ClamFanotif: unable to start clamonacc. (bad context)\n");
return CL_EARG;
}
onas_fan_fd = (*ctx)->fan_fd;
(*ctx)->fan_mask = fan_mask;
if (optget((*ctx)->clamdopts, "OnAccessPrevention")->enabled && !optget((*ctx)->clamdopts, "OnAccessMountPath")->enabled) {
logg("*ClamFanotif: kernel-level blocking feature enabled ... preventing malicious files access attempts\n");
(*ctx)->fan_mask |= FAN_ACCESS_PERM | FAN_OPEN_PERM;
} else {
logg("*ClamFanotif: kernel-level blocking feature disabled ...\n");
if (optget((*ctx)->clamdopts, "OnAccessPrevention")->enabled && optget((*ctx)->clamdopts, "OnAccessMountPath")->enabled) {
logg("*ClamFanotif: feature not available when watching mounts ... \n");
}
(*ctx)->fan_mask |= FAN_ACCESS | FAN_OPEN;
}
if ((pt = optget((*ctx)->clamdopts, "OnAccessMountPath"))->enabled) {
while (pt) {
if (fanotify_mark(onas_fan_fd, FAN_MARK_ADD | FAN_MARK_MOUNT, (*ctx)->fan_mask, (*ctx)->fan_fd, pt->strarg) != 0) {
logg("!ClamFanotif: can't include mountpoint '%s'\n", pt->strarg);
return CL_EARG;
} else {
logg("*ClamFanotif: recursively watching the mount point '%s'\n", pt->strarg);
}
pt = (struct optstruct *)pt->nextarg;
}
} else if (!optget((*ctx)->clamdopts, "OnAccessDisableDDD")->enabled) {
(*ctx)->ddd_enabled = 1;
} else {
if ((pt = optget((*ctx)->clamdopts, "OnAccessIncludePath"))->enabled) {
while (pt) {
if (fanotify_mark(onas_fan_fd, FAN_MARK_ADD, (*ctx)->fan_mask, (*ctx)->fan_fd, pt->strarg) != 0) {
logg("!ClamFanotif: can't include path '%s'\n", pt->strarg);
return CL_EARG;
} else {
logg("*ClamFanotif: watching directory '%s' (non-recursively)\n", pt->strarg);
}
pt = (struct optstruct *)pt->nextarg;
}
} else {
logg("!ClamFanotif: please specify at least one path with OnAccessIncludePath\n");
return CL_EARG;
}
}
/* Load other options. */
(*ctx)->sizelimit = optget((*ctx)->clamdopts, "OnAccessMaxFileSize")->numarg;
if ((*ctx)->sizelimit) {
logg("*ClamFanotif: max file size limited to %lu bytes\n", (*ctx)->sizelimit);
} else {
logg("*ClamFanotif: file size limit disabled\n");
}
extinfo = optget((*ctx)->clamdopts, "ExtendedDetectionInfo")->enabled;
return CL_SUCCESS;
}
int onas_fan_eloop(struct onas_context **ctx)
{
int ret = 0;
int err_cnt = 0;
short int scan;
STATBUF sb;
fd_set rfds;
char buf[4096];
ssize_t bread;
struct fanotify_event_metadata *fmd;
char fname[1024];
int len, check, fres;
char err[128];
FD_ZERO(&rfds);
FD_SET((*ctx)->fan_fd, &rfds);
logg("*ClamFanotif: starting fanotify event loop with process id (%d) ... \n", getpid());
do {
ret = select((*ctx)->fan_fd + 1, &rfds, NULL, NULL, NULL);
} while ((ret == -1 && errno == EINTR));
time_t start = time(NULL) - 30;
while (((bread = read((*ctx)->fan_fd, buf, sizeof(buf))) > 0) || (errno == EOVERFLOW || errno == EMFILE || errno == EACCES)) {
switch (errno) {
case EOVERFLOW:
if (time(NULL) - start >= 30) {
logg("*ClamFanotif: internal error (failed to read data) ... %s\n", strerror(errno));
logg("*ClamFanotif: file too large for fanotify ... recovering and continuing scans...\n");
start = time(NULL);
}
errno = 0;
continue;
case EACCES:
logg("*ClamFanotif: internal error (failed to read data) ... %s\n", strerror(errno));
logg("*ClamFanotif: check your SELinux audit logs and consider adding an exception \
... recovering and continuing scans...\n");
errno = 0;
continue;
case EMFILE:
logg("*ClamFanotif: internal error (failed to read data) ... %s\n", strerror(errno));
logg("*ClamFanotif: waiting for consumer thread to catch up then retrying ...\n");
sleep(3);
errno = 0;
continue;
default:
break;
}
fmd = (struct fanotify_event_metadata *)buf;
while (FAN_EVENT_OK(fmd, bread)) {
scan = 1;
if (fmd->fd >= 0) {
sprintf(fname, "/proc/self/fd/%d", fmd->fd);
errno = 0;
len = readlink(fname, fname, sizeof(fname) - 1);
if (len == -1) {
close(fmd->fd);
logg("!ClamFanotif: internal error (readlink() failed), %d, %s\n", fmd->fd, strerror(errno));
if (errno == EBADF) {
logg("ClamWorker: fd already closed ... recovering ...\n");
continue;
} else {
return 2;
}
}
fname[len] = '\0';
if ((check = onas_fan_checkowner(fmd->pid, (*ctx)->clamdopts))) {
scan = 0;
if (check != CHK_SELF) {
logg("*ClamFanotif: %s skipped (excluded UID)\n", fname);
}
}
if (scan) {
struct onas_scan_event *event_data;
event_data = cli_calloc(1, sizeof(struct onas_scan_event));
if (NULL == event_data) {
logg("!ClamFanotif: could not allocate memory for event data struct\n");
return 2;
}
/* general mapping */
onas_map_context_info_to_event_data(*ctx, &event_data);
scan ? event_data->bool_opts |= ONAS_SCTH_B_SCAN : scan;
/* fanotify specific stuffs */
event_data->bool_opts |= ONAS_SCTH_B_FANOTIFY;
event_data->fmd = cli_malloc(sizeof(struct fanotify_event_metadata));
if (NULL == event_data->fmd) {
logg("!ClamFanotif: could not allocate memory for event data struct fmd\n");
return 2;
}
memcpy(event_data->fmd, fmd, sizeof(struct fanotify_event_metadata));
event_data->pathname = cli_strdup(fname);
logg("*ClamFanotif: attempting to feed consumer queue\n");
/* feed consumer queue */
if (CL_SUCCESS != onas_queue_event(event_data)) {
close(fmd->fd);
logg("!ClamFanotif: error occurred while feeding consumer queue ... \n");
if ((*ctx)->retry_on_error) {
err_cnt++;
if (err_cnt < (*ctx)->retry_attempts) {
logg("ClamFanotif: ... recovering ...\n");
continue;
}
}
return 2;
}
} else {
if (fmd->mask & FAN_ALL_PERM_EVENTS) {
struct fanotify_response res;
res.fd = fmd->fd;
res.response = FAN_ALLOW;
if (-1 == write((*ctx)->fan_fd, &res, sizeof(res))) {
logg("!ClamFanotif: error occurred while excluding event\n");
return 2;
}
}
if (-1 == close(fmd->fd)) {
logg("!ClamFanotif: error occurred while closing metadata fd, %d\n", fmd->fd);
if (errno == EBADF) {
logg("ClamFanotif: fd already closed ... recovering ...\n");
} else {
return 2;
}
}
}
}
fmd = FAN_EVENT_NEXT(fmd, bread);
}
do {
ret = select((*ctx)->fan_fd + 1, &rfds, NULL, NULL, NULL);
} while ((ret == -1 && errno == EINTR));
}
if (bread < 0) {
logg("!ClamFanotif: internal error (failed to read data) ... %s\n", strerror(errno));
return 2;
}
return ret;
}
#endif