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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 const struct xt_icmp_names icmp_codes[] = {
{ "any", 0xFF, 0, 0xFF },
{ "echo-reply", 0, 0, 0xFF },
/* Alias */ { "pong", 0, 0, 0xFF },
{ "destination-unreachable", 3, 0, 0xFF },
{ "network-unreachable", 3, 0, 0 },
{ "host-unreachable", 3, 1, 1 },
{ "protocol-unreachable", 3, 2, 2 },
{ "port-unreachable", 3, 3, 3 },
{ "fragmentation-needed", 3, 4, 4 },
{ "source-route-failed", 3, 5, 5 },
{ "network-unknown", 3, 6, 6 },
{ "host-unknown", 3, 7, 7 },
{ "network-prohibited", 3, 9, 9 },
{ "host-prohibited", 3, 10, 10 },
{ "TOS-network-unreachable", 3, 11, 11 },
{ "TOS-host-unreachable", 3, 12, 12 },
{ "communication-prohibited", 3, 13, 13 },
{ "host-precedence-violation", 3, 14, 14 },
{ "precedence-cutoff", 3, 15, 15 },
{ "source-quench", 4, 0, 0xFF },
{ "redirect", 5, 0, 0xFF },
{ "network-redirect", 5, 0, 0 },
{ "host-redirect", 5, 1, 1 },
{ "TOS-network-redirect", 5, 2, 2 },
{ "TOS-host-redirect", 5, 3, 3 },
{ "echo-request", 8, 0, 0xFF },
/* Alias */ { "ping", 8, 0, 0xFF },
{ "router-advertisement", 9, 0, 0xFF },
{ "router-solicitation", 10, 0, 0xFF },
{ "time-exceeded", 11, 0, 0xFF },
/* Alias */ { "ttl-exceeded", 11, 0, 0xFF },
{ "ttl-zero-during-transit", 11, 0, 0 },
{ "ttl-zero-during-reassembly", 11, 1, 1 },
{ "parameter-problem", 12, 0, 0xFF },
{ "ip-header-bad", 12, 0, 0 },
{ "required-option-missing", 12, 1, 1 },
{ "timestamp-request", 13, 0, 0xFF },
{ "timestamp-reply", 14, 0, 0xFF },
{ "address-mask-request", 17, 0, 0xFF },
{ "address-mask-reply", 18, 0, 0xFF }
};
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
parse_icmp(const char *icmptype, uint8_t *type, uint8_t code[])
{
static const unsigned int limit = ARRAY_SIZE(icmp_codes);
unsigned int match = limit;
unsigned int i;
for (i = 0; i < limit; i++) {
if (strncasecmp(icmp_codes[i].name, icmptype, strlen(icmptype))
== 0) {
if (match != limit)
xtables_error(PARAMETER_PROBLEM,
"Ambiguous ICMP type `%s':"
" `%s' or `%s'?",
icmptype,
icmp_codes[match].name,
icmp_codes[i].name);
match = i;
}
}
if (match != limit) {
*type = icmp_codes[match].type;
code[0] = icmp_codes[match].code_min;
code[1] = icmp_codes[match].code_max;
} else {
char *slash;
char buffer[strlen(icmptype) + 1];
unsigned int number;
strcpy(buffer, icmptype);
slash = strchr(buffer, '/');
if (slash)
*slash = '\0';
if (!xtables_strtoui(buffer, NULL, &number, 0, UINT8_MAX))
xtables_error(PARAMETER_PROBLEM,
"Invalid ICMP type `%s'\n", buffer);
*type = number;
if (slash) {
if (!xtables_strtoui(slash+1, NULL, &number, 0, UINT8_MAX))
xtables_error(PARAMETER_PROBLEM,
"Invalid ICMP code `%s'\n",
slash+1);
code[0] = code[1] = number;
} else {
code[0] = 0;
code[1] = 0xFF;
}
}
}
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);
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, 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;
}
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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