[net-next-2.6.git] / net / ipv6 / netfilter / ip6t_REJECT.c

/*
 * IP6 tables REJECT target module
 * Linux INET6 implementation
 *
 * Copyright (C)2003 USAGI/WIDE Project
 *
 * Authors:
 *	Yasuyuki Kozakai	<yasuyuki.kozakai@toshiba.co.jp>
 *
 * Based on net/ipv4/netfilter/ipt_REJECT.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/icmpv6.h>
#include <linux/netdevice.h>
#include <net/ipv6.h>
#include <net/tcp.h>
#include <net/icmp.h>
#include <net/ip6_checksum.h>
#include <net/ip6_fib.h>
#include <net/ip6_route.h>
#include <net/flow.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_REJECT.h>

MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv6");
MODULE_LICENSE("GPL");

/* Send RST reply */
static void send_reset(struct net *net, struct sk_buff *oldskb)
{
	struct sk_buff *nskb;
	struct tcphdr otcph, *tcph;
	unsigned int otcplen, hh_len;
	int tcphoff, needs_ack;
	const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
	struct ipv6hdr *ip6h;
	struct dst_entry *dst = NULL;
	u8 proto;
	struct flowi fl;

	if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
	    (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
		pr_debug("addr is not unicast.\n");
		return;
	}

	proto = oip6h->nexthdr;
	tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto);

	if ((tcphoff < 0) || (tcphoff > oldskb->len)) {
		pr_debug("Cannot get TCP header.\n");
		return;
	}

	otcplen = oldskb->len - tcphoff;

	/* IP header checks: fragment, too short. */
	if (proto != IPPROTO_TCP || otcplen < sizeof(struct tcphdr)) {
		pr_debug("proto(%d) != IPPROTO_TCP, "
			 "or too short. otcplen = %d\n",
			 proto, otcplen);
		return;
	}

	if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
		BUG();

	/* No RST for RST. */
	if (otcph.rst) {
		pr_debug("RST is set\n");
		return;
	}

	/* Check checksum. */
	if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
			    skb_checksum(oldskb, tcphoff, otcplen, 0))) {
		pr_debug("TCP checksum is invalid\n");
		return;
	}

	memset(&fl, 0, sizeof(fl));
	fl.proto = IPPROTO_TCP;
	ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr);
	ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr);
	fl.fl_ip_sport = otcph.dest;
	fl.fl_ip_dport = otcph.source;
	security_skb_classify_flow(oldskb, &fl);
	dst = ip6_route_output(net, NULL, &fl);
	if (dst == NULL)
		return;
	if (dst->error || xfrm_lookup(net, &dst, &fl, NULL, 0))
		return;

	hh_len = (dst->dev->hard_header_len + 15)&~15;
	nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
			 + sizeof(struct tcphdr) + dst->trailer_len,
			 GFP_ATOMIC);

	if (!nskb) {
		if (net_ratelimit())
			pr_debug("cannot alloc skb\n");
		dst_release(dst);
		return;
	}

	skb_dst_set(nskb, dst);

	skb_reserve(nskb, hh_len + dst->header_len);

	skb_put(nskb, sizeof(struct ipv6hdr));
	skb_reset_network_header(nskb);
	ip6h = ipv6_hdr(nskb);
	ip6h->version = 6;
	ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT);
	ip6h->nexthdr = IPPROTO_TCP;
	ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr);
	ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr);

	tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
	/* Truncate to length (no data) */
	tcph->doff = sizeof(struct tcphdr)/4;
	tcph->source = otcph.dest;
	tcph->dest = otcph.source;

	if (otcph.ack) {
		needs_ack = 0;
		tcph->seq = otcph.ack_seq;
		tcph->ack_seq = 0;
	} else {
		needs_ack = 1;
		tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
				      + otcplen - (otcph.doff<<2));
		tcph->seq = 0;
	}

	/* Reset flags */
	((u_int8_t *)tcph)[13] = 0;
	tcph->rst = 1;
	tcph->ack = needs_ack;
	tcph->window = 0;
	tcph->urg_ptr = 0;
	tcph->check = 0;

	/* Adjust TCP checksum */
	tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr,
				      &ipv6_hdr(nskb)->daddr,
				      sizeof(struct tcphdr), IPPROTO_TCP,
				      csum_partial(tcph,
						   sizeof(struct tcphdr), 0));

	nf_ct_attach(nskb, oldskb);

	ip6_local_out(nskb);
}

static inline void
send_unreach(struct net *net, struct sk_buff *skb_in, unsigned char code,
	     unsigned int hooknum)
{
	if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL)
		skb_in->dev = net->loopback_dev;

	icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0);
}

static unsigned int
reject_tg6(struct sk_buff *skb, const struct xt_target_param *par)
{
	const struct ip6t_reject_info *reject = par->targinfo;
	struct net *net = dev_net((par->in != NULL) ? par->in : par->out);

	pr_debug("%s: medium point\n", __func__);
	switch (reject->with) {
	case IP6T_ICMP6_NO_ROUTE:
		send_unreach(net, skb, ICMPV6_NOROUTE, par->hooknum);
		break;
	case IP6T_ICMP6_ADM_PROHIBITED:
		send_unreach(net, skb, ICMPV6_ADM_PROHIBITED, par->hooknum);
		break;
	case IP6T_ICMP6_NOT_NEIGHBOUR:
		send_unreach(net, skb, ICMPV6_NOT_NEIGHBOUR, par->hooknum);
		break;
	case IP6T_ICMP6_ADDR_UNREACH:
		send_unreach(net, skb, ICMPV6_ADDR_UNREACH, par->hooknum);
		break;
	case IP6T_ICMP6_PORT_UNREACH:
		send_unreach(net, skb, ICMPV6_PORT_UNREACH, par->hooknum);
		break;
	case IP6T_ICMP6_ECHOREPLY:
		/* Do nothing */
		break;
	case IP6T_TCP_RESET:
		send_reset(net, skb);
		break;
	default:
		if (net_ratelimit())
			pr_info("case %u not handled yet\n", reject->with);
		break;
	}

	return NF_DROP;
}

static int reject_tg6_check(const struct xt_tgchk_param *par)
{
	const struct ip6t_reject_info *rejinfo = par->targinfo;
	const struct ip6t_entry *e = par->entryinfo;

	if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
		pr_info("ECHOREPLY is not supported.\n");
		return -EINVAL;
	} else if (rejinfo->with == IP6T_TCP_RESET) {
		/* Must specify that it's a TCP packet */
		if (e->ipv6.proto != IPPROTO_TCP ||
		    (e->ipv6.invflags & XT_INV_PROTO)) {
			pr_info("TCP_RESET illegal for non-tcp\n");
			return -EINVAL;
		}
	}
	return 0;
}

static struct xt_target reject_tg6_reg __read_mostly = {
	.name		= "REJECT",
	.family		= NFPROTO_IPV6,
	.target		= reject_tg6,
	.targetsize	= sizeof(struct ip6t_reject_info),
	.table		= "filter",
	.hooks		= (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD) |
			  (1 << NF_INET_LOCAL_OUT),
	.checkentry	= reject_tg6_check,
	.me		= THIS_MODULE
};

static int __init reject_tg6_init(void)
{
	return xt_register_target(&reject_tg6_reg);
}

static void __exit reject_tg6_exit(void)
{
	xt_unregister_target(&reject_tg6_reg);
}

module_init(reject_tg6_init);
module_exit(reject_tg6_exit);
Commit	Line	Data
764d8a9f PM	1	/*
	2	* IP6 tables REJECT target module
	3	* Linux INET6 implementation
	4	*
	5	* Copyright (C)2003 USAGI/WIDE Project
	6	*
	7	* Authors:
	8	* Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
	9	*
	10	* Based on net/ipv4/netfilter/ipt_REJECT.c
	11	*
	12	* This program is free software; you can redistribute it and/or
	13	* modify it under the terms of the GNU General Public License
	14	* as published by the Free Software Foundation; either version
	15	* 2 of the License, or (at your option) any later version.
	16	*/
ff67e4e4	17	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
764d8a9f PM	18	#include <linux/module.h>
	19	#include <linux/skbuff.h>
	20	#include <linux/icmpv6.h>
	21	#include <linux/netdevice.h>
	22	#include <net/ipv6.h>
	23	#include <net/tcp.h>
	24	#include <net/icmp.h>
	25	#include <net/ip6_checksum.h>
	26	#include <net/ip6_fib.h>
	27	#include <net/ip6_route.h>
	28	#include <net/flow.h>
6709dbbb	29	#include <linux/netfilter/x_tables.h>
764d8a9f PM	30	#include <linux/netfilter_ipv6/ip6_tables.h>
	31	#include <linux/netfilter_ipv6/ip6t_REJECT.h>
	32
	33	MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
2ae15b64	34	MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv6");
764d8a9f PM	35	MODULE_LICENSE("GPL");
764d8a9f PM	36
764d8a9f	37	/* Send RST reply */
e10aad99	38	static void send_reset(struct net net, struct sk_buff oldskb)
764d8a9f PM	39	{
	40	struct sk_buff *nskb;
	41	struct tcphdr otcph, *tcph;
	42	unsigned int otcplen, hh_len;
	43	int tcphoff, needs_ack;
3cf93c96 JE	44	const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
3cf93c96 JE	45	struct ipv6hdr *ip6h;
764d8a9f PM	46	struct dst_entry *dst = NULL;
	47	u8 proto;
	48	struct flowi fl;
	49
	50	if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) \|\|
	51	(!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
ff67e4e4	52	pr_debug("addr is not unicast.\n");
764d8a9f PM	53	return;
	54	}
	55
	56	proto = oip6h->nexthdr;
	57	tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto);
	58
	59	if ((tcphoff < 0) \|\| (tcphoff > oldskb->len)) {
ff67e4e4	60	pr_debug("Cannot get TCP header.\n");
764d8a9f PM	61	return;
	62	}
	63
	64	otcplen = oldskb->len - tcphoff;
	65
	66	/* IP header checks: fragment, too short. */
7c4e36bc	67	if (proto != IPPROTO_TCP \|\| otcplen < sizeof(struct tcphdr)) {
ff67e4e4	68	pr_debug("proto(%d) != IPPROTO_TCP, "
0d53778e PM	69	"or too short. otcplen = %d\n",
0d53778e PM	70	proto, otcplen);
764d8a9f PM	71	return;
	72	}
	73
	74	if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
	75	BUG();
	76
	77	/* No RST for RST. */
	78	if (otcph.rst) {
ff67e4e4	79	pr_debug("RST is set\n");
764d8a9f PM	80	return;
	81	}
	82
	83	/* Check checksum. */
	84	if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
	85	skb_checksum(oldskb, tcphoff, otcplen, 0))) {
ff67e4e4	86	pr_debug("TCP checksum is invalid\n");
764d8a9f PM	87	return;
	88	}
	89
	90	memset(&fl, 0, sizeof(fl));
	91	fl.proto = IPPROTO_TCP;
	92	ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr);
	93	ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr);
	94	fl.fl_ip_sport = otcph.dest;
	95	fl.fl_ip_dport = otcph.source;
beb8d13b	96	security_skb_classify_flow(oldskb, &fl);
e10aad99	97	dst = ip6_route_output(net, NULL, &fl);
764d8a9f PM	98	if (dst == NULL)
764d8a9f PM	99	return;
52479b62	100	if (dst->error \|\| xfrm_lookup(net, &dst, &fl, NULL, 0))
764d8a9f	101	return;
764d8a9f PM	102
	103	hh_len = (dst->dev->hard_header_len + 15)&~15;
	104	nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
	105	+ sizeof(struct tcphdr) + dst->trailer_len,
	106	GFP_ATOMIC);
	107
	108	if (!nskb) {
	109	if (net_ratelimit())
ff67e4e4	110	pr_debug("cannot alloc skb\n");
764d8a9f PM	111	dst_release(dst);
	112	return;
	113	}
	114
adf30907	115	skb_dst_set(nskb, dst);
764d8a9f PM	116
	117	skb_reserve(nskb, hh_len + dst->header_len);
	118
1ced98e8 ACM	119	skb_put(nskb, sizeof(struct ipv6hdr));
1ced98e8 ACM	120	skb_reset_network_header(nskb);
0660e03f	121	ip6h = ipv6_hdr(nskb);
764d8a9f PM	122	ip6h->version = 6;
	123	ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT);
	124	ip6h->nexthdr = IPPROTO_TCP;
764d8a9f PM	125	ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr);
	126	ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr);
	127
	128	tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
	129	/* Truncate to length (no data) */
	130	tcph->doff = sizeof(struct tcphdr)/4;
	131	tcph->source = otcph.dest;
	132	tcph->dest = otcph.source;
	133
	134	if (otcph.ack) {
	135	needs_ack = 0;
	136	tcph->seq = otcph.ack_seq;
	137	tcph->ack_seq = 0;
	138	} else {
	139	needs_ack = 1;
	140	tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
	141	+ otcplen - (otcph.doff<<2));
	142	tcph->seq = 0;
	143	}
	144
	145	/* Reset flags */
	146	((u_int8_t *)tcph)[13] = 0;
	147	tcph->rst = 1;
	148	tcph->ack = needs_ack;
	149	tcph->window = 0;
	150	tcph->urg_ptr = 0;
	151	tcph->check = 0;
	152
	153	/* Adjust TCP checksum */
0660e03f ACM	154	tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr,
0660e03f ACM	155	&ipv6_hdr(nskb)->daddr,
764d8a9f	156	sizeof(struct tcphdr), IPPROTO_TCP,
a47362a2	157	csum_partial(tcph,
764d8a9f PM	158	sizeof(struct tcphdr), 0));
764d8a9f PM	159
08857fa7 YK	160	nf_ct_attach(nskb, oldskb);
08857fa7 YK	161
ef76bc23	162	ip6_local_out(nskb);
764d8a9f PM	163	}
	164
	165	static inline void
e10aad99 AD	166	send_unreach(struct net net, struct sk_buff skb_in, unsigned char code,
e10aad99 AD	167	unsigned int hooknum)
764d8a9f	168	{
6e23ae2a	169	if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL)
e10aad99	170	skb_in->dev = net->loopback_dev;
764d8a9f	171
3ffe533c	172	icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0);
764d8a9f PM	173	}
764d8a9f PM	174
d3c5ee6d	175	static unsigned int
7eb35586	176	reject_tg6(struct sk_buff skb, const struct xt_target_param par)
764d8a9f	177	{
7eb35586 JE	178	const struct ip6t_reject_info *reject = par->targinfo;
7eb35586 JE	179	struct net *net = dev_net((par->in != NULL) ? par->in : par->out);
764d8a9f	180
0dc47877	181	pr_debug("%s: medium point\n", __func__);
1ab1457c YH	182	switch (reject->with) {
1ab1457c YH	183	case IP6T_ICMP6_NO_ROUTE:
7eb35586	184	send_unreach(net, skb, ICMPV6_NOROUTE, par->hooknum);
1ab1457c YH	185	break;
1ab1457c YH	186	case IP6T_ICMP6_ADM_PROHIBITED:
7eb35586	187	send_unreach(net, skb, ICMPV6_ADM_PROHIBITED, par->hooknum);
1ab1457c YH	188	break;
1ab1457c YH	189	case IP6T_ICMP6_NOT_NEIGHBOUR:
7eb35586	190	send_unreach(net, skb, ICMPV6_NOT_NEIGHBOUR, par->hooknum);
1ab1457c YH	191	break;
1ab1457c YH	192	case IP6T_ICMP6_ADDR_UNREACH:
7eb35586	193	send_unreach(net, skb, ICMPV6_ADDR_UNREACH, par->hooknum);
1ab1457c YH	194	break;
1ab1457c YH	195	case IP6T_ICMP6_PORT_UNREACH:
7eb35586	196	send_unreach(net, skb, ICMPV6_PORT_UNREACH, par->hooknum);
1ab1457c YH	197	break;
1ab1457c YH	198	case IP6T_ICMP6_ECHOREPLY:
764d8a9f PM	199	/* Do nothing */
	200	break;
	201	case IP6T_TCP_RESET:
e10aad99	202	send_reset(net, skb);
764d8a9f PM	203	break;
	204	default:
	205	if (net_ratelimit())
ff67e4e4	206	pr_info("case %u not handled yet\n", reject->with);
764d8a9f PM	207	break;
	208	}
	209
	210	return NF_DROP;
	211	}
	212
135367b8	213	static int reject_tg6_check(const struct xt_tgchk_param *par)
764d8a9f	214	{
af5d6dc2 JE	215	const struct ip6t_reject_info *rejinfo = par->targinfo;
af5d6dc2 JE	216	const struct ip6t_entry *e = par->entryinfo;
764d8a9f	217
764d8a9f	218	if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
ff67e4e4	219	pr_info("ECHOREPLY is not supported.\n");
d6b00a53	220	return -EINVAL;
764d8a9f PM	221	} else if (rejinfo->with == IP6T_TCP_RESET) {
764d8a9f PM	222	/* Must specify that it's a TCP packet */
3666ed1c JP	223	if (e->ipv6.proto != IPPROTO_TCP \|\|
3666ed1c JP	224	(e->ipv6.invflags & XT_INV_PROTO)) {
ff67e4e4	225	pr_info("TCP_RESET illegal for non-tcp\n");
d6b00a53	226	return -EINVAL;
764d8a9f PM	227	}
764d8a9f PM	228	}
d6b00a53	229	return 0;
764d8a9f PM	230	}
764d8a9f PM	231
d3c5ee6d	232	static struct xt_target reject_tg6_reg __read_mostly = {
764d8a9f	233	.name = "REJECT",
ee999d8b	234	.family = NFPROTO_IPV6,
d3c5ee6d	235	.target = reject_tg6,
7f939713 PM	236	.targetsize = sizeof(struct ip6t_reject_info),
7f939713 PM	237	.table = "filter",
6e23ae2a PM	238	.hooks = (1 << NF_INET_LOCAL_IN) \| (1 << NF_INET_FORWARD) \|
6e23ae2a PM	239	(1 << NF_INET_LOCAL_OUT),
d3c5ee6d	240	.checkentry = reject_tg6_check,
764d8a9f PM	241	.me = THIS_MODULE
	242	};
	243
d3c5ee6d	244	static int __init reject_tg6_init(void)
764d8a9f	245	{
d3c5ee6d	246	return xt_register_target(&reject_tg6_reg);
764d8a9f PM	247	}
764d8a9f PM	248
d3c5ee6d	249	static void __exit reject_tg6_exit(void)
764d8a9f	250	{
d3c5ee6d	251	xt_unregister_target(&reject_tg6_reg);
764d8a9f PM	252	}
764d8a9f PM	253
d3c5ee6d JE	254	module_init(reject_tg6_init);
d3c5ee6d JE	255	module_exit(reject_tg6_exit);