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#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <xtables.h>
#include <limits.h> /* INT_MAX in ip6_tables.h */
#include <linux/netfilter_ipv4/ip_tables.h>
#include "libxt_icmp.h"
/* special hack for icmp-type 'any':
* Up to kernel <=2.4.20 the problem was:
* '-p icmp ' matches all icmp packets
* '-p icmp -m icmp' matches _only_ ICMP type 0 :(
* This is now fixed by initializing the field * to icmp type 0xFF
* See: https://bugzilla.netfilter.org/cgi-bin/bugzilla/show_bug.cgi?id=37
*/
enum {
O_ICMP_TYPE = 0,
};
static void icmp_help(void)
{
printf(
"icmp match options:\n"
"[!] --icmp-type typename match icmp type\n"
"[!] --icmp-type type[/code] (or numeric type or type/code)\n");
printf("Valid ICMP Types:");
xt_print_icmp_types(icmp_codes, ARRAY_SIZE(icmp_codes));
}
static const struct xt_option_entry icmp_opts[] = {
{.name = "icmp-type", .id = O_ICMP_TYPE, .type = XTTYPE_STRING,
.flags = XTOPT_MAND | XTOPT_INVERT},
XTOPT_TABLEEND,
};
static void icmp_init(struct xt_entry_match *m)
{
struct ipt_icmp *icmpinfo = (struct ipt_icmp *)m->data;
icmpinfo->type = 0xFF;
icmpinfo->code[1] = 0xFF;
}
static void icmp_parse(struct xt_option_call *cb)
{
struct ipt_icmp *icmpinfo = cb->data;
xtables_option_parse(cb);
ipt_parse_icmp(cb->arg, &icmpinfo->type, icmpinfo->code);
if (cb->invert)
icmpinfo->invflags |= IPT_ICMP_INV;
}
static void print_icmptype(uint8_t type,
uint8_t code_min, uint8_t code_max,
int invert,
int numeric)
{
if (!numeric) {
unsigned int i;
for (i = 0; i < ARRAY_SIZE(icmp_codes); ++i)
if (icmp_codes[i].type == type
&& icmp_codes[i].code_min == code_min
&& icmp_codes[i].code_max == code_max)
break;
if (i != ARRAY_SIZE(icmp_codes)) {
printf(" %s%s",
invert ? "!" : "",
icmp_codes[i].name);
return;
}
}
if (invert)
printf(" !");
printf("type %u", type);
if (code_min == code_max)
printf(" code %u", code_min);
else if (code_min != 0 || code_max != 0xFF)
printf(" codes %u-%u", code_min, code_max);
}
static void icmp_print(const void *ip, const struct xt_entry_match *match,
int numeric)
{
const struct ipt_icmp *icmp = (struct ipt_icmp *)match->data;
printf(" icmp");
print_icmptype(icmp->type, icmp->code[0], icmp->code[1],
icmp->invflags & IPT_ICMP_INV,
numeric);
if (icmp->invflags & ~IPT_ICMP_INV)
printf(" Unknown invflags: 0x%X",
icmp->invflags & ~IPT_ICMP_INV);
}
static void icmp_save(const void *ip, const struct xt_entry_match *match)
{
const struct ipt_icmp *icmp = (struct ipt_icmp *)match->data;
if (icmp->invflags & IPT_ICMP_INV)
printf(" !");
/* special hack for 'any' case */
if (icmp->type == 0xFF) {
printf(" --icmp-type any");
} else {
printf(" --icmp-type %u", icmp->type);
if (icmp->code[0] != 0 || icmp->code[1] != 0xFF)
printf("/%u", icmp->code[0]);
}
}
static unsigned int type_xlate_print(struct xt_xlate *xl, unsigned int icmptype,
unsigned int code_min,
unsigned int code_max)
{
unsigned int i;
if (code_min != code_max) {
for (i = 0; i < ARRAY_SIZE(icmp_codes); ++i)
if (icmp_codes[i].type == icmptype &&
icmp_codes[i].code_min == code_min &&
icmp_codes[i].code_max == code_max) {
xt_xlate_add(xl, "%s", icmp_codes[i].name);
return 1;
}
}
return 0;
}
static int icmp_xlate(struct xt_xlate *xl,
const struct xt_xlate_mt_params *params)
{
const struct ipt_icmp *info = (struct ipt_icmp *)params->match->data;
if (info->type != 0xFF) {
xt_xlate_add(xl, "icmp type%s ",
(info->invflags & IPT_ICMP_INV) ? " !=" : "");
if (!type_xlate_print(xl, info->type, info->code[0],
info->code[1]))
return 0;
} else {
/* '-m icmp --icmp-type any' is a noop by itself,
* but it eats a (mandatory) previous '-p icmp' so
* emit it here */
xt_xlate_add(xl, "ip protocol icmp");
}
return 1;
}
static struct xtables_match icmp_mt_reg = {
.name = "icmp",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV4,
.size = XT_ALIGN(sizeof(struct ipt_icmp)),
.userspacesize = XT_ALIGN(sizeof(struct ipt_icmp)),
.help = icmp_help,
.init = icmp_init,
.print = icmp_print,
.save = icmp_save,
.x6_parse = icmp_parse,
.x6_options = icmp_opts,
.xlate = icmp_xlate,
};
void _init(void)
{
xtables_register_match(&icmp_mt_reg);
}
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