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/*
* Copyright (C) 2014-2021 Firejail Authors
*
* This file is part of firejail project
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "fnettrace.h"
#define MAX_BUF_SIZE (64 * 1024)
static int arg_netfilter = 0;
static char *arg_log = NULL;
typedef struct hlist_t {
struct hlist_t *next;
uint32_t ip_src;
uint32_t ip_dst;
uint16_t port_src;
uint64_t bytes;
int instance;
#define MAX_TTL 20 // 20 * DISPLAY_INTERVAL = 1 minute
short ttl;
uint8_t protocol;
} HList;
#define HMAX 256
HList *htable[HMAX] = {NULL};
static int htable_empty = 1;
static void hlist_add(uint32_t ip_src, uint32_t ip_dst, uint8_t protocol, uint16_t port_src, uint64_t bytes) {
uint8_t h = hash(ip_src);
htable_empty = 0;
// find
int instance = 0;
HList *ptr = htable[h];
while (ptr) {
if (ptr->ip_src == ip_src) {
instance++;
if (ptr->ip_dst == ip_dst && ptr->port_src == port_src && ptr->protocol == protocol) {
ptr->bytes += bytes;
ptr->ttl = MAX_TTL;
return;
}
}
ptr = ptr->next;
}
HList *hnew = malloc(sizeof(HList));
hnew->ip_src = ip_src;
hnew->ip_dst = ip_dst;
hnew->port_src = port_src;
hnew->protocol = protocol;
hnew->next = NULL;
hnew->bytes = bytes;
hnew->ttl = MAX_TTL;
hnew->instance = instance + 1;
if (htable[h] == NULL)
htable[h] = hnew;
else {
hnew->next = htable[h];
htable[h] = hnew;
}
ansi_clrline(1);
logprintf(" %d%d.%d.%d\n", PRINT_IP(hnew->ip_src));
}
// remove entries with a ttl <= 0
static void hlist_clean_ttl() {
if (htable_empty)
return;
int i;
for (i = 0; i < HMAX; i++) {
HList *ptr = htable[i];
HList *parent = NULL;
while (ptr) {
if (--ptr->ttl <= 0) {
HList *tmp = ptr;
ptr = ptr->next;
if (parent)
parent->next = ptr;
else
htable[i] = ptr;
free(tmp);
}
else {
parent = ptr;
ptr = ptr->next;
}
}
}
}
static void hlist_print() {
ansi_clrscr(0);
if (htable_empty)
return;
if (arg_netfilter)
printf("\n\n");
int i;
int cnt = 0;
int cnt_printed = 0;
for (i = 0; i < HMAX; i++) {
HList *ptr = htable[i];
while (ptr) {
if (ptr->bytes) {
cnt_printed++;
char ip_src[30];
sprintf(ip_src, "%d.%d.%d.%d:%u", PRINT_IP(ptr->ip_src), ptr->port_src);
char ip_dst[30];
sprintf(ip_dst, "%d.%d.%d.%d", PRINT_IP(ptr->ip_dst));
printf("%-25s => %-25s\t%s:",
ip_src,
ip_dst,
(ptr->protocol == 6)? "TCP": "UDP");
if (ptr->bytes > (DISPLAY_INTERVAL * 1024 * 2)) // > 2 KB/second
printf(" %lu KB/sec\n",
ptr->bytes / (DISPLAY_INTERVAL * 1024));
else
printf(" %lu B/sec\n",
ptr->bytes / DISPLAY_INTERVAL);
ptr->bytes = 0;
}
ptr = ptr->next;
cnt++;
}
}
if (cnt_printed < 7) {
for (i = 0; i < 7 - cnt_printed; i++)
printf("\n");
}
if (!arg_netfilter) {
printf("(%d %s in the last one minute)\n", cnt, (cnt == 1)? "stream": "streams");
hlist_clean_ttl();
}
}
static void run_trace(void) {
logprintf("accumulating traffic for %d seconds...\n", NETLOCK_INTERVAL);
// trace only rx ipv4 tcp and upd
int s1 = socket(AF_INET, SOCK_RAW, IPPROTO_TCP);
int s2 = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
if (s1 < 0 || s2 < 0)
errExit("socket");
unsigned start = time(NULL);
unsigned last_print_traces = 0;
unsigned last_print_remaining = 0;
unsigned char buf[MAX_BUF_SIZE];
while (1) {
unsigned end = time(NULL);
if (arg_netfilter && end - start >= NETLOCK_INTERVAL) {
ansi_clrline(1);
break;
}
if (end % DISPLAY_INTERVAL == 1 && last_print_traces != end) { // first print after 1 second
hlist_print();
last_print_traces = end;
}
if (arg_netfilter && last_print_remaining != end) {
ansi_clrline(1);
int secs = NETLOCK_INTERVAL - (end - start);
logprintf("%d %s remaining ", secs, (secs == 1)? "second": "seconds");
last_print_remaining = end;
}
fd_set rfds;
FD_ZERO(&rfds);
FD_SET(s1, &rfds);
FD_SET(s2, &rfds);
int maxfd = (s1 > s2) ? s1 : s2;
maxfd++;
struct timeval tv;
tv.tv_sec = 1;
tv.tv_usec = 0;
int rv = select(maxfd, &rfds, NULL, NULL, &tv);
if (rv < 0)
errExit("select");
else if (rv == 0)
continue;
int sock = (FD_ISSET(s1, &rfds)) ? s1 : s2;
unsigned bytes = recvfrom(sock, buf, MAX_BUF_SIZE, 0, NULL, NULL);
if (bytes >= 20) { // size of IP header
// filter out loopback traffic
if (buf[12] != 127) {
uint32_t ip_src;
memcpy(&ip_src, buf + 12, 4);
ip_src = ntohl(ip_src);
uint32_t ip_dst;
memcpy(&ip_dst, buf + 16, 4);
ip_dst = ntohl(ip_dst);
uint8_t hlen = (buf[0] & 0x0f) * 4;
uint16_t port_src;
memcpy(&port_src, buf + hlen, 2);
port_src = ntohs(port_src);
hlist_add(ip_src, ip_dst, buf[9], port_src, (uint64_t) bytes);
}
}
}
close(s1);
close(s2);
}
static char *filter_start =
"*filter\n"
":INPUT DROP [0:0]\n"
":FORWARD DROP [0:0]\n"
":OUTPUT DROP [0:0]\n";
// return 1 if error
static int print_filter(FILE *fp) {
if (htable_empty)
return 1;
fprintf(fp, "%s\n", filter_start);
fprintf(fp, "-A INPUT -s 127.0.0.0/8 -j ACCEPT\n");
fprintf(fp, "-A OUTPUT -d 127.0.0.0/8 -j ACCEPT\n");
fprintf(fp, "\n");
int i;
for (i = 0; i < HMAX; i++) {
HList *ptr = htable[i];
while (ptr) {
if (ptr->instance == 1) {
char *protocol = (ptr->protocol == 6)? "tcp": "udp";
fprintf(fp, "-A INPUT -s %d.%d.%d.%d -sport %u -p %s -j ACCEPT\n",
PRINT_IP(ptr->ip_src),
ptr->port_src,
protocol);
fprintf(fp, "-A OUTPUT -d %d.%d.%d.%d -dport %u -p %s -j ACCEPT\n",
PRINT_IP(ptr->ip_src),
ptr->port_src,
protocol);
fprintf(fp, "\n");
}
ptr = ptr->next;
}
}
fprintf(fp, "COMMIT\n");
return 0;
}
static char *flush_rules[] = {
"-P INPUT ACCEPT",
"-P FORWARD ACCEPT",
"-P OUTPUT ACCEPT",
"-F",
"-X",
"-t nat -F",
"-t nat -X",
"-t mangle -F",
"-t mangle -X",
"iptables -t raw -F",
"-t raw -X",
NULL
};
static void flush_netfilter(void) {
// find iptables command
struct stat s;
char *iptables = NULL;
if (stat("/sbin/iptables", &s) == 0)
iptables = "/sbin/iptables";
else if (stat("/usr/sbin/iptables", &s) == 0)
iptables = "/usr/sbin/iptables";
if (iptables == NULL) {
fprintf(stderr, "Error: iptables command not found, netfilter not configured\n");
exit(1);
}
int i = 0;
while (flush_rules[i]) {
char *cmd;
if (asprintf(&cmd, "%s %s", iptables, flush_rules[i]) == -1)
errExit("asprintf");
int rv = system(cmd);
(void) rv;
free(cmd);
i++;
}
}
static void deploy_netfilter(void) {
int rv;
char *cmd;
// create temporary file
char fname[] = "/tmp/firejail-XXXXXX";
int fd = mkstemp(fname);
if (fd == -1) {
fprintf(stderr, "Error: cannot create temporary configuration file\n");
exit(1);
}
FILE* fp = fdopen(fd, "w");
if (!fp) {
rv = unlink(fname);
(void) rv;
fprintf(stderr, "Error: cannot create temporary configuration file\n");
exit(1);
}
print_filter(fp);
fclose(fp);
if (arg_log) {
logprintf("\n");
logprintf(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
if (asprintf(&cmd, "cat %s >> %s", fname, arg_log) == -1)
errExit("asprintf");
rv = system(cmd);
(void) rv;
free(cmd);
logprintf("<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
}
// find iptables command
struct stat s;
char *iptables = NULL;
char *iptables_restore = NULL;
if (stat("/sbin/iptables", &s) == 0) {
iptables = "/sbin/iptables";
iptables_restore = "/sbin/iptables-restore";
}
else if (stat("/usr/sbin/iptables", &s) == 0) {
iptables = "/usr/sbin/iptables";
iptables_restore = "/usr/sbin/iptables-restore";
}
if (iptables == NULL || iptables_restore == NULL) {
fprintf(stderr, "Error: iptables command not found, netfilter not configured\n");
rv = unlink(fname);
(void) rv;
exit(1);
}
// configuring
if (asprintf(&cmd, "%s %s", iptables_restore, fname) == -1)
errExit("asprintf");
rv = system(cmd);
if (rv)
fprintf(stdout, "Warning: possible netfilter problem!");
free(cmd);
sleep(1);
if (asprintf(&cmd, "%s %s", iptables_restore, fname) == -1)
errExit("asprintf");
rv = system(cmd);
free(cmd);
printf("Current firewall configuration:\n\n");
if (asprintf(&cmd, "%s -vL -n", iptables) == -1)
errExit("asprintf");
rv = system(cmd);
rv = unlink(fname);
(void) rv;
logprintf("\nfirewall deployed\n");
}
void logprintf(char* fmt, ...) {
if (!arg_log)
return;
FILE *fp = fopen(arg_log, "a");
if (fp) { // disregard if error
va_list args;
va_start(args,fmt);
vfprintf(fp, fmt, args);
va_end(args);
fclose(fp);
}
}
static void usage(void) {
printf("Usage: fnetlock [OPTIONS]\n");
printf("Options:\n");
printf(" --help, -? - this help screen\n");
printf(" --netfilter - build the firewall rules and commit them.\n");
printf(" --log=filename - logfile\n");
printf("\n");
}
int main(int argc, char **argv) {
int i;
printf("\n\n");
if (getuid() != 0) {
fprintf(stderr, "Error: you need to be root to run this program\n");
return 1;
}
for (i = 1; i < argc; i++) {
if (strcmp(argv[i], "--help") == 0 || strcmp(argv[i], "-?") == 0) {
usage();
return 0;
}
else if (strcmp(argv[i], "--netfilter") == 0)
arg_netfilter = 1;
else if (strncmp(argv[i], "--log=", 6) == 0)
arg_log = argv[i] + 6;
else {
fprintf(stderr, "Error: invalid argument\n");
return 1;
}
}
if (arg_netfilter) {
logprintf("starting network lockdown\n");
flush_netfilter();
}
ansi_clrscr(0);
run_trace();
if (arg_netfilter) {
deploy_netfilter();
sleep(3);
if (arg_log)
unlink(arg_log);
}
return 0;
}
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