policy: merge ipv6 and ipv4 variant

The files duplicate most of their code, and struct ipt_policy_info
being defined to xt_policy_info makes them actually have even more in
common.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>

1 files changed, 513 insertions, 0 deletions

diff --git a/extensions/libxt_policy.c b/extensions/libxt_policy.c
new file mode 100644
index 00000000..d17b1bbc
--- /dev/null
+++ b/extensions/libxt_policy.c
@@ -0,0 +1,513 @@
+/* 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);
+}