extensions/libxt_policy.c - maze/iptables - Git at Google

 /* Shared library add-on to iptables to add policy support. */
 #include <stdio.h>
 #include <netdb.h>
 #include <string.h>
 #include <stdlib.h>
 #include <syslog.h>
 #include <getopt.h>
 #include <netdb.h>
 #include <errno.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <xtables.h>

 #include <linux/netfilter/xt_policy.h>

 /*
  * HACK: global pointer to current matchinfo for making
  * final checks and adjustments in final_check.
  */
 static struct xt_policy_info *policy_info;

 static void policy_help(void)
 {
 	printf(
 "policy match options:\n"
 "  --dir in|out			match policy applied during decapsulation/\n"
 "				policy to be applied during encapsulation\n"
 "  --pol none|ipsec		match policy\n"
 "  --strict 			match entire policy instead of single element\n"
 "				at any position\n"
 "[!] --reqid reqid		match reqid\n"
 "[!] --spi spi			match SPI\n"
 "[!] --proto proto		match protocol (ah/esp/ipcomp)\n"
 "[!] --mode mode 		match mode (transport/tunnel)\n"
 "[!] --tunnel-src addr/mask	match tunnel source\n"
 "[!] --tunnel-dst addr/mask	match tunnel destination\n"
 "  --next 			begin next element in policy\n");
 }

 static const struct option policy_opts[] =
 {
 	{
 		.name		= "dir",
 		.has_arg	= 1,
 		.val		= '1',
 	},
 	{
 		.name		= "pol",
 		.has_arg	= 1,
 		.val		= '2',
 	},
 	{
 		.name		= "strict",
 		.val		= '3'
 	},
 	{
 		.name		= "reqid",
 		.has_arg	= 1,
 		.val		= '4',
 	},
 	{
 		.name		= "spi",
 		.has_arg	= 1,
 		.val		= '5'
 	},
 	{
 		.name		= "tunnel-src",
 		.has_arg	= 1,
 		.val		= '6'
 	},
 	{
 		.name		= "tunnel-dst",
 		.has_arg	= 1,
 		.val		= '7'
 	},
 	{
 		.name		= "proto",
 		.has_arg	= 1,
 		.val		= '8'
 	},
 	{
 		.name		= "mode",
 		.has_arg	= 1,
 		.val		= '9'
 	},
 	{
 		.name		= "next",
 		.val		= 'a'
 	},
 	{ .name = NULL }
 };

 static int parse_direction(char *s)
 {
 	if (strcmp(s, "in") == 0)
 		return XT_POLICY_MATCH_IN;
 	if (strcmp(s, "out") == 0)
 		return XT_POLICY_MATCH_OUT;
 	xtables_error(PARAMETER_PROBLEM, "policy_match: invalid dir \"%s\"", s);
 }

 static int parse_policy(char *s)
 {
 	if (strcmp(s, "none") == 0)
 		return XT_POLICY_MATCH_NONE;
 	if (strcmp(s, "ipsec") == 0)
 		return 0;
 	xtables_error(PARAMETER_PROBLEM, "policy match: invalid policy \"%s\"", s);
 }

 static int parse_mode(char *s)
 {
 	if (strcmp(s, "transport") == 0)
 		return XT_POLICY_MODE_TRANSPORT;
 	if (strcmp(s, "tunnel") == 0)
 		return XT_POLICY_MODE_TUNNEL;
 	xtables_error(PARAMETER_PROBLEM, "policy match: invalid mode \"%s\"", s);
 }

 static int policy_parse(int c, int invert, unsigned int *flags,
                         struct xt_policy_info *info, uint8_t family)
 {
 	struct xt_policy_elem *e = &info->pol[info->len];
 	struct in_addr *addr = NULL, mask;
 	struct in6_addr *addr6 = NULL, mask6;
 	unsigned int naddr = 0, num;
 	int mode;

 	xtables_check_inverse(optarg, &invert, &optind, 0);

 	switch (c) {
 	case '1':
 		if (info->flags & (XT_POLICY_MATCH_IN | XT_POLICY_MATCH_OUT))
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: double --dir option");
 		if (invert)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: can't invert --dir option");

 		info->flags |= parse_direction(optarg);
 		break;
 	case '2':
 		if (invert)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: can't invert --policy option");

 		info->flags |= parse_policy(optarg);
 		break;
 	case '3':
 		if (info->flags & XT_POLICY_MATCH_STRICT)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: double --strict option");

 		if (invert)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: can't invert --strict option");

 		info->flags |= XT_POLICY_MATCH_STRICT;
 		break;
 	case '4':
 		if (e->match.reqid)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: double --reqid option");

 		e->match.reqid = 1;
 		e->invert.reqid = invert;
 		if (!xtables_strtoui(optarg, NULL, &num, 0, UINT32_MAX))
 			xtables_param_act(XTF_BAD_VALUE, "policy", "--spi", optarg);
 		e->reqid = num;
 		break;
 	case '5':
 		if (e->match.spi)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: double --spi option");

 		e->match.spi = 1;
 		e->invert.spi = invert;
 		if (!xtables_strtoui(optarg, NULL, &num, 0, UINT32_MAX))
 			xtables_param_act(XTF_BAD_VALUE, "policy", "--spi", optarg);
 		e->spi = num;
 		break;
 	case '6':
 		if (e->match.saddr)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: double --tunnel-src option");

 		if (family == NFPROTO_IPV6)
 			xtables_ip6parse_any(optarg, &addr6, &mask6, &naddr);
 		else
 			xtables_ipparse_any(optarg, &addr, &mask, &naddr);
 		if (naddr > 1)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: name resolves to multiple IPs");

 		e->match.saddr = 1;
 		e->invert.saddr = invert;
 		if (family == NFPROTO_IPV6) {
 			memcpy(&e->saddr.a6, addr6, sizeof(*addr6));
 			memcpy(&e->smask.a6, &mask6, sizeof(mask6));
 		} else {
 			e->saddr.a4 = addr[0];
 			e->smask.a4 = mask;
 		}
                 break;
 	case '7':
 		if (e->match.daddr)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: double --tunnel-dst option");

 		if (family == NFPROTO_IPV6)
 			xtables_ip6parse_any(optarg, &addr6, &mask6, &naddr);
 		else
 			xtables_ipparse_any(optarg, &addr, &mask, &naddr);
 		if (naddr > 1)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: name resolves to multiple IPs");

 		e->match.daddr = 1;
 		e->invert.daddr = invert;
 		if (family == NFPROTO_IPV6) {
 			memcpy(&e->daddr.a6, addr6, sizeof(*addr6));
 			memcpy(&e->dmask.a6, &mask6, sizeof(mask6));
 		} else {
 			e->daddr.a4 = addr[0];
 			e->dmask.a4 = mask;
 		}
 		break;
 	case '8':
 		if (e->match.proto)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: double --proto option");

 		e->proto = xtables_parse_protocol(optarg);
 		if (e->proto != IPPROTO_AH && e->proto != IPPROTO_ESP &&
 		    e->proto != IPPROTO_COMP)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: protocol must ah/esp/ipcomp");
 		e->match.proto = 1;
 		e->invert.proto = invert;
 		break;
 	case '9':
 		if (e->match.mode)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: double --mode option");

 		mode = parse_mode(optarg);
 		e->match.mode = 1;
 		e->invert.mode = invert;
 		e->mode = mode;
 		break;
 	case 'a':
 		if (invert)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: can't invert --next option");

 		if (++info->len == XT_POLICY_MAX_ELEM)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: maximum policy depth reached");
 		break;
 	default:
 		return 0;
 	}

 	policy_info = info;
 	return 1;
 }

 static int policy4_parse(int c, char **argv, int invert, unsigned int *flags,
                          const void *entry, struct xt_entry_match **match)
 {
 	return policy_parse(c, invert, flags, (void *)(*match)->data,
 	       NFPROTO_IPV4);
 }

 static int policy6_parse(int c, char **argv, int invert, unsigned int *flags,
                         const void *entry, struct xt_entry_match **match)
 {
 	return policy_parse(c, invert, flags, (void *)(*match)->data,
 	       NFPROTO_IPV6);
 }

 static void policy_check(unsigned int flags)
 {
 	struct xt_policy_info *info = policy_info;
 	struct xt_policy_elem *e;
 	int i;

 	if (info == NULL)
 		xtables_error(PARAMETER_PROBLEM,
 		           "policy match: no parameters given");

 	if (!(info->flags & (XT_POLICY_MATCH_IN | XT_POLICY_MATCH_OUT)))
 		xtables_error(PARAMETER_PROBLEM,
 		           "policy match: neither --in nor --out specified");

 	if (info->flags & XT_POLICY_MATCH_NONE) {
 		if (info->flags & XT_POLICY_MATCH_STRICT)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: policy none but --strict given");

 		if (info->len != 0)
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: policy none but policy given");
 	} else
 		info->len++;	/* increase len by 1, no --next after last element */

 	if (!(info->flags & XT_POLICY_MATCH_STRICT) && info->len > 1)
 		xtables_error(PARAMETER_PROBLEM,
 		           "policy match: multiple elements but no --strict");

 	for (i = 0; i < info->len; i++) {
 		e = &info->pol[i];

 		if (info->flags & XT_POLICY_MATCH_STRICT &&
 		    !(e->match.reqid || e->match.spi || e->match.saddr ||
 		      e->match.daddr || e->match.proto || e->match.mode))
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: empty policy element");

 		if ((e->match.saddr || e->match.daddr)
 		    && ((e->mode == XT_POLICY_MODE_TUNNEL && e->invert.mode) ||
 		        (e->mode == XT_POLICY_MODE_TRANSPORT && !e->invert.mode)))
 			xtables_error(PARAMETER_PROBLEM,
 			           "policy match: --tunnel-src/--tunnel-dst "
 			           "is only valid in tunnel mode");
 	}
 }

 static void print_mode(const char *prefix, u_int8_t mode, int numeric)
 {
 	printf("%smode ", prefix);

 	switch (mode) {
 	case XT_POLICY_MODE_TRANSPORT:
 		printf("transport ");
 		break;
 	case XT_POLICY_MODE_TUNNEL:
 		printf("tunnel ");
 		break;
 	default:
 		printf("??? ");
 		break;
 	}
 }

 static void print_proto(const char *prefix, u_int8_t proto, int numeric)
 {
 	struct protoent *p = NULL;

 	printf("%sproto ", prefix);
 	if (!numeric)
 		p = getprotobynumber(proto);
 	if (p != NULL)
 		printf("%s ", p->p_name);
 	else
 		printf("%u ", proto);
 }

 #define PRINT_INVERT(x)		\
 do {				\
 	if (x)			\
 		printf("! ");	\
 } while(0)

 static void print_entry(const char *prefix, const struct xt_policy_elem *e,
                         bool numeric, uint8_t family)
 {
 	if (e->match.reqid) {
 		PRINT_INVERT(e->invert.reqid);
 		printf("%sreqid %u ", prefix, e->reqid);
 	}
 	if (e->match.spi) {
 		PRINT_INVERT(e->invert.spi);
 		printf("%sspi 0x%x ", prefix, e->spi);
 	}
 	if (e->match.proto) {
 		PRINT_INVERT(e->invert.proto);
 		print_proto(prefix, e->proto, numeric);
 	}
 	if (e->match.mode) {
 		PRINT_INVERT(e->invert.mode);
 		print_mode(prefix, e->mode, numeric);
 	}
 	if (e->match.daddr) {
 		PRINT_INVERT(e->invert.daddr);
 		if (family == NFPROTO_IPV6)
 			printf("%stunnel-dst %s%s ", prefix,
 			       xtables_ip6addr_to_numeric(&e->daddr.a6),
 			       xtables_ip6mask_to_numeric(&e->dmask.a6));
 		else
 			printf("%stunnel-dst %s%s ", prefix,
 			       xtables_ipaddr_to_numeric(&e->daddr.a4),
 			       xtables_ipmask_to_numeric(&e->dmask.a4));
 	}
 	if (e->match.saddr) {
 		PRINT_INVERT(e->invert.saddr);
 		if (family == NFPROTO_IPV6)
 			printf("%stunnel-src %s%s ", prefix,
 			       xtables_ip6addr_to_numeric(&e->saddr.a6),
 			       xtables_ip6mask_to_numeric(&e->smask.a6));
 		else
 			printf("%stunnel-src %s%s ", prefix,
 			       xtables_ipaddr_to_numeric(&e->saddr.a4),
 			       xtables_ipmask_to_numeric(&e->smask.a4));
 	}
 }

 static void print_flags(char *prefix, const struct xt_policy_info *info)
 {
 	if (info->flags & XT_POLICY_MATCH_IN)
 		printf("%sdir in ", prefix);
 	else
 		printf("%sdir out ", prefix);

 	if (info->flags & XT_POLICY_MATCH_NONE)
 		printf("%spol none ", prefix);
 	else
 		printf("%spol ipsec ", prefix);

 	if (info->flags & XT_POLICY_MATCH_STRICT)
 		printf("%sstrict ", prefix);
 }

 static void policy4_print(const void *ip, const struct xt_entry_match *match,
                           int numeric)
 {
 	const struct xt_policy_info *info = (void *)match->data;
 	unsigned int i;

 	printf("policy match ");
 	print_flags("", info);
 	for (i = 0; i < info->len; i++) {
 		if (info->len > 1)
 			printf("[%u] ", i);
 		print_entry("", &info->pol[i], numeric, NFPROTO_IPV4);
 	}
 }

 static void policy6_print(const void *ip, const struct xt_entry_match *match,
                           int numeric)
 {
 	const struct xt_policy_info *info = (void *)match->data;
 	unsigned int i;

 	printf("policy match ");
 	print_flags("", info);
 	for (i = 0; i < info->len; i++) {
 		if (info->len > 1)
 			printf("[%u] ", i);
 		print_entry("", &info->pol[i], numeric, NFPROTO_IPV6);
 	}
 }

 static void policy4_save(const void *ip, const struct xt_entry_match *match)
 {
 	const struct xt_policy_info *info = (void *)match->data;
 	unsigned int i;

 	print_flags("--", info);
 	for (i = 0; i < info->len; i++) {
 		print_entry("--", &info->pol[i], false, NFPROTO_IPV4);
 		if (i + 1 < info->len)
 			printf("--next ");
 	}
 }

 static void policy6_save(const void *ip, const struct xt_entry_match *match)
 {
 	const struct xt_policy_info *info = (void *)match->data;
 	unsigned int i;

 	print_flags("--", info);
 	for (i = 0; i < info->len; i++) {
 		print_entry("--", &info->pol[i], false, NFPROTO_IPV6);
 		if (i + 1 < info->len)
 			printf("--next ");
 	}
 }

 static struct xtables_match policy_mt_reg = {
 	.name		= "policy",
 	.version	= XTABLES_VERSION,
 	.family		= NFPROTO_IPV4,
 	.size		= XT_ALIGN(sizeof(struct xt_policy_info)),
 	.userspacesize	= XT_ALIGN(sizeof(struct xt_policy_info)),
 	.help		= policy_help,
 	.parse		= policy4_parse,
 	.final_check	= policy_check,
 	.print		= policy4_print,
 	.save		= policy4_save,
 	.extra_opts	= policy_opts,
 };

 static struct xtables_match policy_mt6_reg = {
 	.name		= "policy",
 	.version	= XTABLES_VERSION,
 	.family		= NFPROTO_IPV6,
 	.size		= XT_ALIGN(sizeof(struct xt_policy_info)),
 	.userspacesize	= XT_ALIGN(sizeof(struct xt_policy_info)),
 	.help		= policy_help,
 	.parse		= policy6_parse,
 	.final_check	= policy_check,
 	.print		= policy6_print,
 	.save		= policy6_save,
 	.extra_opts	= policy_opts,
 };

 void _init(void)
 {
 	xtables_register_match(&policy_mt_reg);
 	xtables_register_match(&policy_mt6_reg);
 }
	/* Shared library add-on to iptables to add policy support. */
	#include <stdio.h>
	#include <netdb.h>
	#include <string.h>
	#include <stdlib.h>
	#include <syslog.h>
	#include <getopt.h>
	#include <netdb.h>
	#include <errno.h>
	#include <sys/socket.h>
	#include <netinet/in.h>
	#include <arpa/inet.h>
	#include <xtables.h>

	#include <linux/netfilter/xt_policy.h>

	/*
	* HACK: global pointer to current matchinfo for making
	* final checks and adjustments in final_check.
	*/
	static struct xt_policy_info *policy_info;

	static void policy_help(void)
	{
	printf(
	"policy match options:\n"
	" --dir in\|out match policy applied during decapsulation/\n"
	" policy to be applied during encapsulation\n"
	" --pol none\|ipsec match policy\n"
	" --strict match entire policy instead of single element\n"
	" at any position\n"
	"[!] --reqid reqid match reqid\n"
	"[!] --spi spi match SPI\n"
	"[!] --proto proto match protocol (ah/esp/ipcomp)\n"
	"[!] --mode mode match mode (transport/tunnel)\n"
	"[!] --tunnel-src addr/mask match tunnel source\n"
	"[!] --tunnel-dst addr/mask match tunnel destination\n"
	" --next begin next element in policy\n");
	}

	static const struct option policy_opts[] =
	{
	{
	.name = "dir",
	.has_arg = 1,
	.val = '1',
	},
	{
	.name = "pol",
	.has_arg = 1,
	.val = '2',
	},
	{
	.name = "strict",
	.val = '3'
	},
	{
	.name = "reqid",
	.has_arg = 1,
	.val = '4',
	},
	{
	.name = "spi",
	.has_arg = 1,
	.val = '5'
	},
	{
	.name = "tunnel-src",
	.has_arg = 1,
	.val = '6'
	},
	{
	.name = "tunnel-dst",
	.has_arg = 1,
	.val = '7'
	},
	{
	.name = "proto",
	.has_arg = 1,
	.val = '8'
	},
	{
	.name = "mode",
	.has_arg = 1,
	.val = '9'
	},
	{
	.name = "next",
	.val = 'a'
	},
	{ .name = NULL }
	};

	static int parse_direction(char *s)
	{
	if (strcmp(s, "in") == 0)
	return XT_POLICY_MATCH_IN;
	if (strcmp(s, "out") == 0)
	return XT_POLICY_MATCH_OUT;
	xtables_error(PARAMETER_PROBLEM, "policy_match: invalid dir \"%s\"", s);
	}

	static int parse_policy(char *s)
	{
	if (strcmp(s, "none") == 0)
	return XT_POLICY_MATCH_NONE;
	if (strcmp(s, "ipsec") == 0)
	return 0;
	xtables_error(PARAMETER_PROBLEM, "policy match: invalid policy \"%s\"", s);
	}

	static int parse_mode(char *s)
	{
	if (strcmp(s, "transport") == 0)
	return XT_POLICY_MODE_TRANSPORT;
	if (strcmp(s, "tunnel") == 0)
	return XT_POLICY_MODE_TUNNEL;
	xtables_error(PARAMETER_PROBLEM, "policy match: invalid mode \"%s\"", s);
	}

	static int policy_parse(int c, int invert, unsigned int *flags,
	struct xt_policy_info *info, uint8_t family)
	{
	struct xt_policy_elem *e = &info->pol[info->len];
	struct in_addr *addr = NULL, mask;
	struct in6_addr *addr6 = NULL, mask6;
	unsigned int naddr = 0, num;
	int mode;

	xtables_check_inverse(optarg, &invert, &optind, 0);

	switch (c) {
	case '1':
	if (info->flags & (XT_POLICY_MATCH_IN \| XT_POLICY_MATCH_OUT))
	xtables_error(PARAMETER_PROBLEM,
	"policy match: double --dir option");
	if (invert)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: can't invert --dir option");

	info->flags \|= parse_direction(optarg);
	break;
	case '2':
	if (invert)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: can't invert --policy option");

	info->flags \|= parse_policy(optarg);
	break;
	case '3':
	if (info->flags & XT_POLICY_MATCH_STRICT)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: double --strict option");

	if (invert)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: can't invert --strict option");

	info->flags \|= XT_POLICY_MATCH_STRICT;
	break;
	case '4':
	if (e->match.reqid)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: double --reqid option");

	e->match.reqid = 1;
	e->invert.reqid = invert;
	if (!xtables_strtoui(optarg, NULL, &num, 0, UINT32_MAX))
	xtables_param_act(XTF_BAD_VALUE, "policy", "--spi", optarg);
	e->reqid = num;
	break;
	case '5':
	if (e->match.spi)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: double --spi option");

	e->match.spi = 1;
	e->invert.spi = invert;
	if (!xtables_strtoui(optarg, NULL, &num, 0, UINT32_MAX))
	xtables_param_act(XTF_BAD_VALUE, "policy", "--spi", optarg);
	e->spi = num;
	break;
	case '6':
	if (e->match.saddr)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: double --tunnel-src option");

	if (family == NFPROTO_IPV6)
	xtables_ip6parse_any(optarg, &addr6, &mask6, &naddr);
	else
	xtables_ipparse_any(optarg, &addr, &mask, &naddr);
	if (naddr > 1)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: name resolves to multiple IPs");

	e->match.saddr = 1;
	e->invert.saddr = invert;
	if (family == NFPROTO_IPV6) {
	memcpy(&e->saddr.a6, addr6, sizeof(*addr6));
	memcpy(&e->smask.a6, &mask6, sizeof(mask6));
	} else {
	e->saddr.a4 = addr[0];
	e->smask.a4 = mask;
	}
	break;
	case '7':
	if (e->match.daddr)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: double --tunnel-dst option");

	if (family == NFPROTO_IPV6)
	xtables_ip6parse_any(optarg, &addr6, &mask6, &naddr);
	else
	xtables_ipparse_any(optarg, &addr, &mask, &naddr);
	if (naddr > 1)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: name resolves to multiple IPs");

	e->match.daddr = 1;
	e->invert.daddr = invert;
	if (family == NFPROTO_IPV6) {
	memcpy(&e->daddr.a6, addr6, sizeof(*addr6));
	memcpy(&e->dmask.a6, &mask6, sizeof(mask6));
	} else {
	e->daddr.a4 = addr[0];
	e->dmask.a4 = mask;
	}
	break;
	case '8':
	if (e->match.proto)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: double --proto option");

	e->proto = xtables_parse_protocol(optarg);
	if (e->proto != IPPROTO_AH && e->proto != IPPROTO_ESP &&
	e->proto != IPPROTO_COMP)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: protocol must ah/esp/ipcomp");
	e->match.proto = 1;
	e->invert.proto = invert;
	break;
	case '9':
	if (e->match.mode)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: double --mode option");

	mode = parse_mode(optarg);
	e->match.mode = 1;
	e->invert.mode = invert;
	e->mode = mode;
	break;
	case 'a':
	if (invert)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: can't invert --next option");

	if (++info->len == XT_POLICY_MAX_ELEM)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: maximum policy depth reached");
	break;
	default:
	return 0;
	}

	policy_info = info;
	return 1;
	}

	static int policy4_parse(int c, char *argv, int invert, unsigned int flags,
	const void entry, struct xt_entry_match *match)
	{
	return policy_parse(c, invert, flags, (void )(match)->data,
	NFPROTO_IPV4);
	}

	static int policy6_parse(int c, char *argv, int invert, unsigned int flags,
	const void entry, struct xt_entry_match *match)
	{
	return policy_parse(c, invert, flags, (void )(match)->data,
	NFPROTO_IPV6);
	}

	static void policy_check(unsigned int flags)
	{
	struct xt_policy_info *info = policy_info;
	struct xt_policy_elem *e;
	int i;

	if (info == NULL)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: no parameters given");

	if (!(info->flags & (XT_POLICY_MATCH_IN \| XT_POLICY_MATCH_OUT)))
	xtables_error(PARAMETER_PROBLEM,
	"policy match: neither --in nor --out specified");

	if (info->flags & XT_POLICY_MATCH_NONE) {
	if (info->flags & XT_POLICY_MATCH_STRICT)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: policy none but --strict given");

	if (info->len != 0)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: policy none but policy given");
	} else
	info->len++; /* increase len by 1, no --next after last element */

	if (!(info->flags & XT_POLICY_MATCH_STRICT) && info->len > 1)
	xtables_error(PARAMETER_PROBLEM,
	"policy match: multiple elements but no --strict");

	for (i = 0; i < info->len; i++) {
	e = &info->pol[i];

	if (info->flags & XT_POLICY_MATCH_STRICT &&
	!(e->match.reqid \|\| e->match.spi \|\| e->match.saddr \|\|
	e->match.daddr \|\| e->match.proto \|\| e->match.mode))
	xtables_error(PARAMETER_PROBLEM,
	"policy match: empty policy element");

	if ((e->match.saddr \|\| e->match.daddr)
	&& ((e->mode == XT_POLICY_MODE_TUNNEL && e->invert.mode) \|\|
	(e->mode == XT_POLICY_MODE_TRANSPORT && !e->invert.mode)))
	xtables_error(PARAMETER_PROBLEM,
	"policy match: --tunnel-src/--tunnel-dst "
	"is only valid in tunnel mode");
	}
	}

	static void print_mode(const char *prefix, u_int8_t mode, int numeric)
	{
	printf("%smode ", prefix);

	switch (mode) {
	case XT_POLICY_MODE_TRANSPORT:
	printf("transport ");
	break;
	case XT_POLICY_MODE_TUNNEL:
	printf("tunnel ");
	break;
	default:
	printf("??? ");
	break;
	}
	}

	static void print_proto(const char *prefix, u_int8_t proto, int numeric)
	{
	struct protoent *p = NULL;

	printf("%sproto ", prefix);
	if (!numeric)
	p = getprotobynumber(proto);
	if (p != NULL)
	printf("%s ", p->p_name);
	else
	printf("%u ", proto);
	}

	#define PRINT_INVERT(x) \
	do { \
	if (x) \
	printf("! "); \
	} while(0)

	static void print_entry(const char prefix, const struct xt_policy_elem e,
	bool numeric, uint8_t family)
	{
	if (e->match.reqid) {
	PRINT_INVERT(e->invert.reqid);
	printf("%sreqid %u ", prefix, e->reqid);
	}
	if (e->match.spi) {
	PRINT_INVERT(e->invert.spi);
	printf("%sspi 0x%x ", prefix, e->spi);
	}
	if (e->match.proto) {
	PRINT_INVERT(e->invert.proto);
	print_proto(prefix, e->proto, numeric);
	}
	if (e->match.mode) {
	PRINT_INVERT(e->invert.mode);
	print_mode(prefix, e->mode, numeric);
	}
	if (e->match.daddr) {
	PRINT_INVERT(e->invert.daddr);
	if (family == NFPROTO_IPV6)
	printf("%stunnel-dst %s%s ", prefix,
	xtables_ip6addr_to_numeric(&e->daddr.a6),
	xtables_ip6mask_to_numeric(&e->dmask.a6));
	else
	printf("%stunnel-dst %s%s ", prefix,
	xtables_ipaddr_to_numeric(&e->daddr.a4),
	xtables_ipmask_to_numeric(&e->dmask.a4));
	}
	if (e->match.saddr) {
	PRINT_INVERT(e->invert.saddr);
	if (family == NFPROTO_IPV6)
	printf("%stunnel-src %s%s ", prefix,
	xtables_ip6addr_to_numeric(&e->saddr.a6),
	xtables_ip6mask_to_numeric(&e->smask.a6));
	else
	printf("%stunnel-src %s%s ", prefix,
	xtables_ipaddr_to_numeric(&e->saddr.a4),
	xtables_ipmask_to_numeric(&e->smask.a4));
	}
	}

	static void print_flags(char prefix, const struct xt_policy_info info)
	{
	if (info->flags & XT_POLICY_MATCH_IN)
	printf("%sdir in ", prefix);
	else
	printf("%sdir out ", prefix);

	if (info->flags & XT_POLICY_MATCH_NONE)
	printf("%spol none ", prefix);
	else
	printf("%spol ipsec ", prefix);

	if (info->flags & XT_POLICY_MATCH_STRICT)
	printf("%sstrict ", prefix);
	}

	static void policy4_print(const void ip, const struct xt_entry_match match,
	int numeric)
	{
	const struct xt_policy_info info = (void )match->data;
	unsigned int i;

	printf("policy match ");
	print_flags("", info);
	for (i = 0; i < info->len; i++) {
	if (info->len > 1)
	printf("[%u] ", i);
	print_entry("", &info->pol[i], numeric, NFPROTO_IPV4);
	}
	}

	static void policy6_print(const void ip, const struct xt_entry_match match,
	int numeric)
	{
	const struct xt_policy_info info = (void )match->data;
	unsigned int i;

	printf("policy match ");
	print_flags("", info);
	for (i = 0; i < info->len; i++) {
	if (info->len > 1)
	printf("[%u] ", i);
	print_entry("", &info->pol[i], numeric, NFPROTO_IPV6);
	}
	}

	static void policy4_save(const void ip, const struct xt_entry_match match)
	{
	const struct xt_policy_info info = (void )match->data;
	unsigned int i;

	print_flags("--", info);
	for (i = 0; i < info->len; i++) {
	print_entry("--", &info->pol[i], false, NFPROTO_IPV4);
	if (i + 1 < info->len)
	printf("--next ");
	}
	}

	static void policy6_save(const void ip, const struct xt_entry_match match)
	{
	const struct xt_policy_info info = (void )match->data;
	unsigned int i;

	print_flags("--", info);
	for (i = 0; i < info->len; i++) {
	print_entry("--", &info->pol[i], false, NFPROTO_IPV6);
	if (i + 1 < info->len)
	printf("--next ");
	}
	}

	static struct xtables_match policy_mt_reg = {
	.name = "policy",
	.version = XTABLES_VERSION,
	.family = NFPROTO_IPV4,
	.size = XT_ALIGN(sizeof(struct xt_policy_info)),
	.userspacesize = XT_ALIGN(sizeof(struct xt_policy_info)),
	.help = policy_help,
	.parse = policy4_parse,
	.final_check = policy_check,
	.print = policy4_print,
	.save = policy4_save,
	.extra_opts = policy_opts,
	};

	static struct xtables_match policy_mt6_reg = {
	.name = "policy",
	.version = XTABLES_VERSION,
	.family = NFPROTO_IPV6,
	.size = XT_ALIGN(sizeof(struct xt_policy_info)),
	.userspacesize = XT_ALIGN(sizeof(struct xt_policy_info)),
	.help = policy_help,
	.parse = policy6_parse,
	.final_check = policy_check,
	.print = policy6_print,
	.save = policy6_save,
	.extra_opts = policy_opts,
	};

	void _init(void)
	{
	xtables_register_match(&policy_mt_reg);
	xtables_register_match(&policy_mt6_reg);
	}