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/*
* Arturo Borrero Gonzalez <arturo@debian.org> adapted
* this code to libxtables for arptables-compat in 2015
*/
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#include <getopt.h>
#include <netinet/ether.h>
#include <xtables.h>
#include <linux/netfilter_arp/arpt_mangle.h>
#include "iptables/nft.h"
static void arpmangle_print_help(void)
{
printf(
"mangle target options:\n"
"--mangle-ip-s IP address\n"
"--mangle-ip-d IP address\n"
"--mangle-mac-s MAC address\n"
"--mangle-mac-d MAC address\n"
"--mangle-target target (DROP, CONTINUE or ACCEPT -- default is ACCEPT)\n");
}
/* internal use only, explicitly not covered by ARPT_MANGLE_MASK */
#define ARPT_MANGLE_TARGET 0x10
static const struct xt_option_entry arpmangle_opts[] = {
{ .name = "mangle-ip-s", .id = ARPT_MANGLE_SIP, .type = XTTYPE_HOSTMASK },
{ .name = "mangle-ip-d", .id = ARPT_MANGLE_TIP, .type = XTTYPE_HOSTMASK },
{ .name = "mangle-mac-s", .id = ARPT_MANGLE_SDEV, .type = XTTYPE_ETHERMAC },
{ .name = "mangle-mac-d", .id = ARPT_MANGLE_TDEV, .type = XTTYPE_ETHERMAC },
{ .name = "mangle-target", .id = ARPT_MANGLE_TARGET, .type = XTTYPE_STRING },
XTOPT_TABLEEND,
};
static void arpmangle_init(struct xt_entry_target *target)
{
struct arpt_mangle *mangle = (struct arpt_mangle *)target->data;
mangle->target = NF_ACCEPT;
}
static void assert_hopts(const struct arpt_entry *e, const char *optname)
{
if (e->arp.arhln_mask == 0)
xtables_error(PARAMETER_PROBLEM, "no --h-length defined");
if (e->arp.invflags & IPT_INV_ARPHLN)
xtables_error(PARAMETER_PROBLEM,
"! hln not allowed for --%s", optname);
if (e->arp.arhln != 6)
xtables_error(PARAMETER_PROBLEM, "only --h-length 6 supported");
}
static void arpmangle_parse(struct xt_option_call *cb)
{
const struct arpt_entry *e = cb->xt_entry;
struct arpt_mangle *mangle = cb->data;
xtables_option_parse(cb);
mangle->flags |= (cb->entry->id & ARPT_MANGLE_MASK);
switch (cb->entry->id) {
case ARPT_MANGLE_SIP:
mangle->u_s.src_ip = cb->val.haddr.in;
break;
case ARPT_MANGLE_TIP:
mangle->u_t.tgt_ip = cb->val.haddr.in;
break;
case ARPT_MANGLE_SDEV:
assert_hopts(e, cb->entry->name);
memcpy(mangle->src_devaddr, cb->val.ethermac, ETH_ALEN);
case ARPT_MANGLE_TDEV:
assert_hopts(e, cb->entry->name);
memcpy(mangle->tgt_devaddr, cb->val.ethermac, ETH_ALEN);
break;
case ARPT_MANGLE_TARGET:
if (!strcmp(cb->arg, "DROP"))
mangle->target = NF_DROP;
else if (!strcmp(cb->arg, "ACCEPT"))
mangle->target = NF_ACCEPT;
else if (!strcmp(cb->arg, "CONTINUE"))
mangle->target = XT_CONTINUE;
else
xtables_error(PARAMETER_PROBLEM,
"bad target for --mangle-target");
break;
}
}
static const char *ipaddr_to(const struct in_addr *addrp, int numeric)
{
if (numeric)
return xtables_ipaddr_to_numeric(addrp);
else
return xtables_ipaddr_to_anyname(addrp);
}
static void
arpmangle_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
struct arpt_mangle *m = (struct arpt_mangle *)(target->data);
if (m->flags & ARPT_MANGLE_SIP) {
printf(" --mangle-ip-s %s",
ipaddr_to(&(m->u_s.src_ip), numeric));
}
if (m->flags & ARPT_MANGLE_SDEV) {
printf(" --mangle-mac-s ");
xtables_print_mac((unsigned char *)m->src_devaddr);
}
if (m->flags & ARPT_MANGLE_TIP) {
printf(" --mangle-ip-d %s",
ipaddr_to(&(m->u_t.tgt_ip), numeric));
}
if (m->flags & ARPT_MANGLE_TDEV) {
printf(" --mangle-mac-d ");
xtables_print_mac((unsigned char *)m->tgt_devaddr);
}
if (m->target != NF_ACCEPT) {
printf(" --mangle-target %s",
m->target == NF_DROP ? "DROP" : "CONTINUE");
}
}
static void arpmangle_save(const void *ip, const struct xt_entry_target *target)
{
arpmangle_print(ip, target, 0);
}
static void print_devaddr_xlate(const char *macaddress, struct xt_xlate *xl)
{
unsigned int i;
xt_xlate_add(xl, "%02x", macaddress[0]);
for (i = 1; i < ETH_ALEN; ++i)
xt_xlate_add(xl, ":%02x", macaddress[i]);
}
static int arpmangle_xlate(struct xt_xlate *xl,
const struct xt_xlate_tg_params *params)
{
const struct arpt_mangle *m = (const void *)params->target->data;
if (m->flags & ARPT_MANGLE_SIP)
xt_xlate_add(xl, "arp saddr ip set %s ",
xtables_ipaddr_to_numeric(&m->u_s.src_ip));
if (m->flags & ARPT_MANGLE_SDEV) {
xt_xlate_add(xl, "arp %caddr ether set ", 's');
print_devaddr_xlate(m->src_devaddr, xl);
}
if (m->flags & ARPT_MANGLE_TIP)
xt_xlate_add(xl, "arp daddr ip set %s ",
xtables_ipaddr_to_numeric(&m->u_t.tgt_ip));
if (m->flags & ARPT_MANGLE_TDEV) {
xt_xlate_add(xl, "arp %caddr ether set ", 'd');
print_devaddr_xlate(m->tgt_devaddr, xl);
}
switch (m->target) {
case NF_ACCEPT:
xt_xlate_add(xl, "accept");
break;
case NF_DROP:
xt_xlate_add(xl, "drop");
break;
default:
break;
}
return 1;
}
static struct xtables_target arpmangle_target = {
.name = "mangle",
.revision = 0,
.version = XTABLES_VERSION,
.family = NFPROTO_ARP,
.size = XT_ALIGN(sizeof(struct arpt_mangle)),
.userspacesize = XT_ALIGN(sizeof(struct arpt_mangle)),
.help = arpmangle_print_help,
.init = arpmangle_init,
.x6_parse = arpmangle_parse,
.print = arpmangle_print,
.save = arpmangle_save,
.x6_options = arpmangle_opts,
.xlate = arpmangle_xlate,
};
void _init(void)
{
xtables_register_target(&arpmangle_target);
}
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