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/*
* Copyright (C) 2014-2018 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 "firejail.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <net/if.h>
#include <stdarg.h>
#include <sys/wait.h>
// configure bridge structure
// - extract ip address and mask from the bridge interface
static void net_configure_bridge(Bridge *br) {
assert(br);
assert(br->dev);
// check the bridge device exists
char sysbridge[30 + strlen(br->dev)];
sprintf(sysbridge, "/sys/class/net/%s/bridge", br->dev);
struct stat s;
int rv = stat(sysbridge, &s);
if (rv == 0) {
// this is a bridge device
br->macvlan = 0;
}
else {
// is this a regular Ethernet interface
if (if_nametoindex(br->dev) > 0) {
br->macvlan = 1;
char *newname;
if (asprintf(&newname, "%s-%u", br->devsandbox, getpid()) == -1)
errExit("asprintf");
br->devsandbox = newname;
}
else {
fprintf(stderr, "Error: cannot find network device %s\n", br->dev);
exit(1);
}
}
int mtu = br->mtu; // preserve mtu value in case the user changed it with --mtu
if (net_get_if_addr(br->dev, &br->ip, &br->mask, br->mac, &br->mtu))
// allow unconfigured interfaces
fwarning("the network interface %s is not configured\n", br->dev);
if (mtu)
br->mtu = mtu;
if (arg_debug) {
if (br->macvlan == 0)
printf("Bridge device %s at %d.%d.%d.%d/%d\n",
br->dev, PRINT_IP(br->ip), mask2bits(br->mask));
else
printf("macvlan parent device %s at %d.%d.%d.%d/%d\n",
br->dev, PRINT_IP(br->ip), mask2bits(br->mask));
}
if (br->mask) {
uint32_t range = ~br->mask + 1; // the number of potential addresses
// this software is not supported for /31 networks
if (range < 4) {
fprintf(stderr, "Error: the software is not supported for /31 networks\n");
exit(1);
}
}
// no interface network mask - no ip address will be configured
if (br->mask == 0)
goto err_no_ip;
// no interface ip - extract the network address from the address configured by the user
else if (br->ip == 0 && br->ipsandbox)
br->ip = br->ipsandbox & br->mask;
// no interface ip - extract the network address from the default gateway configured by the user
else if (br->ip == 0 && cfg.defaultgw)
br->ip = cfg.defaultgw & br->mask;
// no ip address will be configured
else if (br->ip == 0)
goto err_no_ip;
if ((br->iprange_start && in_netrange(br->iprange_start, br->ip, br->mask)) ||
(br->iprange_end && in_netrange(br->iprange_end, br->ip, br->mask))) {
fprintf(stderr, "Error: IP range addresses not in network range\n");
exit(1);
}
return;
err_no_ip:
br->arg_ip_none = 1;
fwarning("Not enough information to configure an IP address for\n interface --net=%s\n", br->dev);
}
void net_configure_sandbox_ip(Bridge *br) {
assert(br);
if (br->configured == 0)
return;
if (br->arg_ip_none)
br->ipsandbox = 0;
else if (br->ipsandbox) {
// check network range
char *rv = in_netrange(br->ipsandbox, br->ip, br->mask);
if (rv) {
fprintf(stderr, "%s", rv);
exit(1);
}
// send an ARP request and check if there is anybody on this IP address
if (arp_check(br->dev, br->ipsandbox)) {
fprintf(stderr, "Error: IP address %d.%d.%d.%d is already in use\n", PRINT_IP(br->ipsandbox));
exit(1);
}
}
else
// ip address assigned by arp-scan for a bridge device
br->ipsandbox = arp_assign(br->dev, br); //br->ip, br->mask);
}
// create a veth pair
// - br - bridge device
// - ifname - interface name in sandbox namespace
// - child - child process running the namespace
void net_configure_veth_pair(Bridge *br, const char *ifname, pid_t child) {
assert(br);
if (br->configured == 0)
return;
// create a veth pair
char *dev;
if (br->veth_name == NULL) {
if (asprintf(&dev, "veth%u%s", getpid(), ifname) < 0)
errExit("asprintf");
}
else
dev = br->veth_name;
char *cstr;
if (asprintf(&cstr, "%d", child) == -1)
errExit("asprintf");
sbox_run(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_SECCOMP, 7, PATH_FNET, "create", "veth", dev, ifname, br->dev, cstr);
free(cstr);
char *msg;
if (asprintf(&msg, "%d.%d.%d.%d address assigned to sandbox", PRINT_IP(br->ipsandbox)) == -1)
errExit("asprintf");
logmsg(msg);
fflush(0);
free(msg);
}
// the default address should be in the range of at least on of the bridge devices
void check_default_gw(uint32_t defaultgw) {
assert(defaultgw);
if (cfg.bridge0.configured) {
char *rv = in_netrange(defaultgw, cfg.bridge0.ip, cfg.bridge0.mask);
if (rv == 0)
return;
}
if (cfg.bridge1.configured) {
char *rv = in_netrange(defaultgw, cfg.bridge1.ip, cfg.bridge1.mask);
if (rv == 0)
return;
}
if (cfg.bridge2.configured) {
char *rv = in_netrange(defaultgw, cfg.bridge2.ip, cfg.bridge2.mask);
if (rv == 0)
return;
}
if (cfg.bridge3.configured) {
char *rv = in_netrange(defaultgw, cfg.bridge3.ip, cfg.bridge3.mask);
if (rv == 0)
return;
}
fprintf(stderr, "Error: default gateway %d.%d.%d.%d is not in the range of any network\n", PRINT_IP(defaultgw));
exit(1);
}
void net_check_cfg(void) {
EUID_ASSERT();
int net_configured = 0;
if (cfg.bridge0.configured) {
net_configure_bridge(&cfg.bridge0);
net_configured++;
}
if (cfg.bridge1.configured) {
net_configure_bridge(&cfg.bridge1);
net_configured++;
}
if (cfg.bridge2.configured) {
net_configure_bridge(&cfg.bridge2);
net_configured++;
}
if (cfg.bridge3.configured) {
net_configure_bridge(&cfg.bridge3);
net_configured++;
}
int if_configured = 0;
if (cfg.interface0.configured)
if_configured++;
if (cfg.interface1.configured)
if_configured++;
if (cfg.interface2.configured)
if_configured++;
if (cfg.interface3.configured)
if_configured++;
// --defaultgw requires a network or an interface
if (cfg.defaultgw && net_configured == 0 && if_configured == 0) {
fprintf(stderr, "Error: option --defaultgw requires at least one network or one interface to be configured\n");
exit(1);
}
if (net_configured == 0) // nothing to check
return;
// --net=none
if (arg_nonetwork && net_configured) {
fprintf(stderr, "Error: --net and --net=none are mutually exclusive\n");
exit(1);
}
// check default gateway address or assign one
assert(cfg.bridge0.configured);
if (cfg.defaultgw)
check_default_gw(cfg.defaultgw);
else {
// first network is a regular bridge
if (cfg.bridge0.macvlan == 0)
cfg.defaultgw = cfg.bridge0.ip;
// first network is a mac device
else {
// get the host default gw
EUID_ROOT(); // rise permissions for grsecurity
// Error fopen:network_get_defaultgw(479): Permission denied
uint32_t gw = network_get_defaultgw();
EUID_USER();
// check the gateway is network range
if (in_netrange(gw, cfg.bridge0.ip, cfg.bridge0.mask))
gw = 0;
cfg.defaultgw = gw;
}
}
}
#define MAXBUF 4096
void net_dns_print(pid_t pid) {
EUID_ASSERT();
// drop privileges - will not be able to read /etc/resolv.conf for --noroot option
// if the pid is that of a firejail process, use the pid of the first child process
EUID_ROOT();
char *comm = pid_proc_comm(pid);
EUID_USER();
if (comm) {
if (strcmp(comm, "firejail") == 0) {
pid_t child;
if (find_child(pid, &child) == 0) {
pid = child;
}
}
free(comm);
}
EUID_ROOT();
if (join_namespace(pid, "mnt"))
exit(1);
pid_t child = fork();
if (child < 0)
errExit("fork");
if (child == 0) {
caps_drop_all();
if (chdir("/") < 0)
errExit("chdir");
// access /etc/resolv.conf
FILE *fp = fopen("/etc/resolv.conf", "r");
if (!fp) {
fprintf(stderr, "Error: cannot access /etc/resolv.conf\n");
exit(1);
}
char buf[MAXBUF];
while (fgets(buf, MAXBUF, fp))
printf("%s", buf);
printf("\n");
fclose(fp);
exit(0);
}
// wait for the child to finish
waitpid(child, NULL, 0);
flush_stdin();
exit(0);
}
void network_main(pid_t child) {
char *cstr;
if (asprintf(&cstr, "%d", child) == -1)
errExit("asprintf");
// create veth pair or macvlan device
if (cfg.bridge0.configured) {
if (cfg.bridge0.macvlan == 0) {
net_configure_veth_pair(&cfg.bridge0, "eth0", child);
}
else
sbox_run(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_SECCOMP, 6, PATH_FNET, "create", "macvlan", cfg.bridge0.devsandbox, cfg.bridge0.dev, cstr);
}
if (cfg.bridge1.configured) {
if (cfg.bridge1.macvlan == 0)
net_configure_veth_pair(&cfg.bridge1, "eth1", child);
else
sbox_run(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_SECCOMP, 6, PATH_FNET, "create", "macvlan", cfg.bridge1.devsandbox, cfg.bridge1.dev, cstr);
}
if (cfg.bridge2.configured) {
if (cfg.bridge2.macvlan == 0)
net_configure_veth_pair(&cfg.bridge2, "eth2", child);
else
sbox_run(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_SECCOMP, 6, PATH_FNET, "create", "macvlan", cfg.bridge2.devsandbox, cfg.bridge2.dev, cstr);
}
if (cfg.bridge3.configured) {
if (cfg.bridge3.macvlan == 0)
net_configure_veth_pair(&cfg.bridge3, "eth3", child);
else
sbox_run(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_SECCOMP, 6, PATH_FNET, "create", "macvlan", cfg.bridge3.devsandbox, cfg.bridge3.dev, cstr);
}
// move interfaces in sandbox
if (cfg.interface0.configured) {
sbox_run(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_SECCOMP, 4, PATH_FNET, "moveif", cfg.interface0.dev, cstr);
}
if (cfg.interface1.configured) {
sbox_run(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_SECCOMP, 4, PATH_FNET, "moveif", cfg.interface1.dev, cstr);
}
if (cfg.interface2.configured) {
sbox_run(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_SECCOMP, 4, PATH_FNET, "moveif", cfg.interface2.dev, cstr);
}
if (cfg.interface3.configured) {
sbox_run(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_SECCOMP, 4, PATH_FNET, "moveif", cfg.interface3.dev, cstr);
}
free(cstr);
}
|