blob: a6e642a2a3824682aaf977aac35bda7575d3678e [file] [log] [blame]
/* Shared library add-on to iptables to add ICMP support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <iptables.h>
#include <linux/netfilter_ipv4/ip_tables.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
*/
struct icmp_names {
const char *name;
u_int8_t type;
u_int8_t code_min, code_max;
};
static const struct 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
print_icmptypes()
{
unsigned int i;
printf("Valid ICMP Types:");
for (i = 0; i < sizeof(icmp_codes)/sizeof(struct icmp_names); i++) {
if (i && icmp_codes[i].type == icmp_codes[i-1].type) {
if (icmp_codes[i].code_min == icmp_codes[i-1].code_min
&& (icmp_codes[i].code_max
== icmp_codes[i-1].code_max))
printf(" (%s)", icmp_codes[i].name);
else
printf("\n %s", icmp_codes[i].name);
}
else
printf("\n%s", icmp_codes[i].name);
}
printf("\n");
}
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"ICMP v%s options:\n"
" --icmp-type [!] typename match icmp type\n"
" (or numeric type or type/code)\n"
"\n", IPTABLES_VERSION);
print_icmptypes();
}
static struct option opts[] = {
{ "icmp-type", 1, 0, '1' },
{0}
};
static void
parse_icmp(const char *icmptype, u_int8_t *type, u_int8_t code[])
{
unsigned int limit = sizeof(icmp_codes)/sizeof(struct icmp_names);
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)
exit_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 (string_to_number(buffer, 0, 255, &number) == -1)
exit_error(PARAMETER_PROBLEM,
"Invalid ICMP type `%s'\n", buffer);
*type = number;
if (slash) {
if (string_to_number(slash+1, 0, 255, &number) == -1)
exit_error(PARAMETER_PROBLEM,
"Invalid ICMP code `%s'\n",
slash+1);
code[0] = code[1] = number;
} else {
code[0] = 0;
code[1] = 0xFF;
}
}
}
/* Initialize the match. */
static void
init(struct ipt_entry_match *m, unsigned int *nfcache)
{
struct ipt_icmp *icmpinfo = (struct ipt_icmp *)m->data;
icmpinfo->type = 0xFF;
icmpinfo->code[1] = 0xFF;
}
/* Function which parses command options; returns true if it
ate an option */
static int
parse(int c, char **argv, int invert, unsigned int *flags,
const struct ipt_entry *entry,
unsigned int *nfcache,
struct ipt_entry_match **match)
{
struct ipt_icmp *icmpinfo = (struct ipt_icmp *)(*match)->data;
switch (c) {
case '1':
if (*flags == 1)
exit_error(PARAMETER_PROBLEM,
"icmp match: only use --icmp-type once!");
check_inverse(optarg, &invert, &optind, 0);
parse_icmp(argv[optind-1], &icmpinfo->type,
icmpinfo->code);
if (invert)
icmpinfo->invflags |= IPT_ICMP_INV;
*flags = 1;
break;
default:
return 0;
}
return 1;
}
static void print_icmptype(u_int8_t type,
u_int8_t code_min, u_int8_t code_max,
int invert,
int numeric)
{
if (!numeric) {
unsigned int i;
for (i = 0;
i < sizeof(icmp_codes)/sizeof(struct icmp_names);
i++) {
if (icmp_codes[i].type == type
&& icmp_codes[i].code_min == code_min
&& icmp_codes[i].code_max == code_max)
break;
}
if (i != sizeof(icmp_codes)/sizeof(struct icmp_names)) {
printf("%s%s ",
invert ? "!" : "",
icmp_codes[i].name);
return;
}
}
if (invert)
printf("!");
printf("type %u", type);
if (code_min == 0 && code_max == 0xFF)
printf(" ");
else if (code_min == code_max)
printf(" code %u ", code_min);
else
printf(" codes %u-%u ", code_min, code_max);
}
/* Prints out the union ipt_matchinfo. */
static void
print(const struct ipt_ip *ip,
const struct ipt_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);
}
/* Saves the match in parsable form to stdout. */
static void save(const struct ipt_ip *ip, const struct ipt_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]);
printf(" ");
}
}
/* Final check; we don't care. We can pass 0xFF to match any type */
static void final_check(unsigned int flags)
{
}
static struct iptables_match icmp = {
.next = NULL,
.name = "icmp",
.version = IPTABLES_VERSION,
.size = IPT_ALIGN(sizeof(struct ipt_icmp)),
.userspacesize = IPT_ALIGN(sizeof(struct ipt_icmp)),
.help = &help,
.init = &init,
.parse = &parse,
.final_check = &final_check,
.print = &print,
.save = &save,
.extra_opts = opts
};
void _init(void)
{
register_match(&icmp);
}