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/* efw_iptables.c -- iptables implementation - updates Linux iptables
*
* GPLv2 - Copyright (C) 2008 David Sommerseth <dazo@users.sourceforge.net>
*
* 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; version 2
* of the License.
*
* 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.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <eurephia_nullsafe.h>
#include <eurephia_log.h>
#include <eurephia_struct.h>
#include <eurephiafw_helpers.h>
#define INTERFACEVER "1.0"
#define INTERFACEAPIVER 1
const char *eFWinterfaceVersion() {
return "eFW-iptables (v"INTERFACEVER") David Sommerseth 2008 (C) GPLv2";
}
int eFWinterfaceAPIversion() {
return INTERFACEAPIVER;
}
int process_input(eurephiaCTX *ctx, const char *fwcmd, const char *msg);
int call_iptables(eurephiaCTX *ctx, const char *fwcmd, char **ipt_args);
void eFW_RunFirewall(void *fwargs) {
efw_threaddata *cfg = (efw_threaddata *) fwargs;
eurephiaCTX *ctx = (eurephiaCTX *) cfg->ctx;
int quit = 0;
unsigned int prio;
char buf[EFW_MSG_SIZE+2];
DEBUG(ctx, 28, "eFW_RunFirewall: Waiting for eFW master to get ready");
sem_wait(cfg->semp_master);
DEBUG(ctx, 28, "eFW_RunFirewall: Telling eFW master that the worker process is ready");
sem_post(cfg->semp_worker);
if( cfg->fw_command == NULL ) {
eurephia_log(ctx, LOG_FATAL, 0,
"eFW_RunFirewall: firewall_command is not configured. "
"iptables will not be updated.");
exit(3);
}
// Main loop ... grab messages of the messague queue until shutdown command is sent, or a failure happens
while( quit == 0 ) {
memset(buf, 0, EFW_MSG_SIZE+2);
if( mq_receive(cfg->msgq, &buf[0], EFW_MSG_SIZE, &prio) == -1 ) {
eurephia_log(ctx, LOG_FATAL, 0,
"eFW_RunFirewall: Error while reading messages from queue: %s",
strerror(errno));
exit(2);
}
quit = (strncmp(buf, "FWSHUTDOWN", 10) == 0 );
if( !quit ) {
int res = 0;
DEBUG(ctx, 20, "eFW_RunFirewall: Received '%s'", buf);
res = process_input(ctx, cfg->fw_command, buf);
if( ! res ) {
quit = 1;
eurephia_log(ctx, LOG_FATAL, 0,
"eFW_RunFirewall: Failed updating iptables");
}
}
}
efwRemoveSemaphores(ctx, fwargs);
efwRemoveMessageQueue(ctx, fwargs);
exit(0);
}
int process_input(eurephiaCTX *ctx, const char *fwcmd, const char *input) {
char mode[3], *macaddr = NULL, *destchain = NULL, *jump = NULL;
char *msg = NULL, *orig_msg = NULL;
char *iptables_args[] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL};
int ret = 0;
orig_msg = strdup_nullsafe(input);
msg = orig_msg;
DEBUG(ctx, 36, "eFW_RunFirewall::process_input(ctx, '%s')", msg);
//
// Simple parsing of the input string
//
mode[0] = '-';
mode[1] = *msg;
mode[2] = 0;
msg += 2;
iptables_args[0] = (char *)fwcmd;
switch( mode[1] ) {
case 'A':
case 'D':
iptables_args[1] = mode;
macaddr = msg; // start of string for macaddr
// Search for end of macaddr and NULL terminate it
destchain = macaddr+1;
while( (*destchain != 0x20) || (*destchain == 0) ) {
destchain++;
}
if( *destchain == 0 ) {
return 0;
}
*destchain = 0; // end of string for macaddr
destchain++; // start of string for destchain
// Search for end of destchain and NULL terminate it
jump = destchain+1;
while( (*jump != 0x20) || (*jump == 0) ) {
jump++;
}
*jump = 0; // end of string for destchain
jump++; // start of string for jump
// Prepare iptables arguments
iptables_args[2] = destchain;
iptables_args[3] = "-m\0";
iptables_args[4] = "mac\0";
iptables_args[5] = "--mac-source\0";
iptables_args[6] = macaddr;
iptables_args[7] = "-m\0";
iptables_args[8] = "state\0";
iptables_args[9] = "--state\0";
iptables_args[10] = "NEW\0";
iptables_args[11] = "-j\0";
iptables_args[12] = jump;
iptables_args[13] = NULL;
eurephia_log(ctx, LOG_INFO, 3, "eFW_RunFirewall - updating iptables rules "
"==> mode: %s macaddr: '%s' destchain: '%s' jump: '%s'",
(mode[1] == 'A' ? "ADD":"DELETE"), macaddr, destchain, jump);
ret = call_iptables(ctx, fwcmd, iptables_args);
break;
case 'F':
iptables_args[1] = mode;
destchain = msg;
iptables_args[2] = destchain;
iptables_args[3] = NULL;
eurephia_log(ctx, LOG_INFO, 3, "eFW_RunFirewall - updating iptables rules "
"==> mode: FLUSH destchain: '%s'", destchain);
ret = call_iptables(ctx, fwcmd, iptables_args);
break;
case 'I':
// Init chain - flush it and then add needed rule for stateful inspection
destchain = msg;
eurephia_log(ctx, LOG_INFO, 3, "eFW_RunFirewall - Initialising iptables chain '%s'",
destchain);
// Flush phase
iptables_args[1] = "-F";
destchain = msg;
iptables_args[2] = destchain;
iptables_args[3] = NULL;
ret = call_iptables(ctx, fwcmd, iptables_args);
// Add stateful inspection
iptables_args[1] = "-I\0";
iptables_args[2] = destchain;
iptables_args[3] = "-m\0";
iptables_args[4] = "state\0";
iptables_args[5] = "--state\0";
iptables_args[6] = "ESTABLISHED,RELATED\0";
iptables_args[7] = "-j\0";
iptables_args[8] = "ACCEPT\0";
ret &= call_iptables(ctx, fwcmd, iptables_args);
break;
default:
eurephia_log(ctx, LOG_CRITICAL, 0, "eFW_RunFirewall::process_input: Malformed update request");
ret = 1;
}
free_nullsafe(orig_msg);
return ret;
}
int call_iptables(eurephiaCTX *ctx, const char *fwcmd, char **ipt_args) {
pid_t pid;
int cmdret = -1;
// Fork out a child process which will run the iptables command. Since the execve replaces
// the current process, we need to do the forking first.
if( (pid = fork()) < 0) {
eurephia_log(ctx, LOG_FATAL, 0,
"eFW_RunFirewall::process_input: Failed to fork process for %s", fwcmd);
return 0;
}
switch( pid ) {
case 0: // child process - execute the program and exit
execve(fwcmd, ipt_args, NULL);
exit(1); // execve should replace the process, but if it fails to do so, make sure we exit
default: // parent process
if( waitpid(pid, &cmdret, 0) != pid ) {
eurephia_log(ctx, LOG_WARNING, 0,
"eFW_RunFirewall::process_input: Failed to wait for process for %s"
" to complete (%s)", fwcmd, strerror(errno));
}
eurephia_log(ctx, LOG_INFO, 4, "eFW_RunFirewall - iptables exited with code: %i ", cmdret);
}
return 1;
}
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