[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.
 */

#include <linux/gfp.h>
#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("ip6t_REJECT: 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("ip6t_REJECT: Can't 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("ip6t_REJECT: 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("ip6t_REJECT: 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("ip6t_REJECT: 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())
			printk("ip6t_REJECT: Can't 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__);
	/* WARNING: This code causes reentry within ip6tables.
	   This means that the ip6tables jump stack is now crap.  We
	   must return an absolute verdict. --RR */
	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())
			printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with);
		break;
	}

	return NF_DROP;
}

static bool 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) {
		printk("ip6t_REJECT: ECHOREPLY is not supported.\n");
		return false;
	} 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)) {
			printk("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
			return false;
		}
	}
	return true;
}

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	*/
	17
5a0e3ad6	18	#include <linux/gfp.h>
764d8a9f PM	19	#include <linux/module.h>
	20	#include <linux/skbuff.h>
	21	#include <linux/icmpv6.h>
	22	#include <linux/netdevice.h>
	23	#include <net/ipv6.h>
	24	#include <net/tcp.h>
	25	#include <net/icmp.h>
	26	#include <net/ip6_checksum.h>
	27	#include <net/ip6_fib.h>
	28	#include <net/ip6_route.h>
	29	#include <net/flow.h>
6709dbbb	30	#include <linux/netfilter/x_tables.h>
764d8a9f PM	31	#include <linux/netfilter_ipv6/ip6_tables.h>
	32	#include <linux/netfilter_ipv6/ip6t_REJECT.h>
	33
	34	MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
2ae15b64	35	MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv6");
764d8a9f PM	36	MODULE_LICENSE("GPL");
764d8a9f PM	37
764d8a9f	38	/* Send RST reply */
e10aad99	39	static void send_reset(struct net net, struct sk_buff oldskb)
764d8a9f PM	40	{
	41	struct sk_buff *nskb;
	42	struct tcphdr otcph, *tcph;
	43	unsigned int otcplen, hh_len;
	44	int tcphoff, needs_ack;
3cf93c96 JE	45	const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
3cf93c96 JE	46	struct ipv6hdr *ip6h;
764d8a9f PM	47	struct dst_entry *dst = NULL;
	48	u8 proto;
	49	struct flowi fl;
	50
	51	if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) \|\|
	52	(!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
0d53778e	53	pr_debug("ip6t_REJECT: addr is not unicast.\n");
764d8a9f PM	54	return;
	55	}
	56
	57	proto = oip6h->nexthdr;
	58	tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto);
	59
	60	if ((tcphoff < 0) \|\| (tcphoff > oldskb->len)) {
0d53778e	61	pr_debug("ip6t_REJECT: Can't get TCP header.\n");
764d8a9f PM	62	return;
	63	}
	64
	65	otcplen = oldskb->len - tcphoff;
	66
	67	/* IP header checks: fragment, too short. */
7c4e36bc	68	if (proto != IPPROTO_TCP \|\| otcplen < sizeof(struct tcphdr)) {
0d53778e PM	69	pr_debug("ip6t_REJECT: proto(%d) != IPPROTO_TCP, "
	70	"or too short. otcplen = %d\n",
	71	proto, otcplen);
764d8a9f PM	72	return;
	73	}
	74
	75	if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
	76	BUG();
	77
	78	/* No RST for RST. */
	79	if (otcph.rst) {
0d53778e	80	pr_debug("ip6t_REJECT: RST is set\n");
764d8a9f PM	81	return;
	82	}
	83
	84	/* Check checksum. */
	85	if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
	86	skb_checksum(oldskb, tcphoff, otcplen, 0))) {
0d53778e	87	pr_debug("ip6t_REJECT: TCP checksum is invalid\n");
764d8a9f PM	88	return;
	89	}
	90
	91	memset(&fl, 0, sizeof(fl));
	92	fl.proto = IPPROTO_TCP;
	93	ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr);
	94	ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr);
	95	fl.fl_ip_sport = otcph.dest;
	96	fl.fl_ip_dport = otcph.source;
beb8d13b	97	security_skb_classify_flow(oldskb, &fl);
e10aad99	98	dst = ip6_route_output(net, NULL, &fl);
764d8a9f PM	99	if (dst == NULL)
764d8a9f PM	100	return;
52479b62	101	if (dst->error \|\| xfrm_lookup(net, &dst, &fl, NULL, 0))
764d8a9f	102	return;
764d8a9f PM	103
	104	hh_len = (dst->dev->hard_header_len + 15)&~15;
	105	nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
	106	+ sizeof(struct tcphdr) + dst->trailer_len,
	107	GFP_ATOMIC);
	108
	109	if (!nskb) {
	110	if (net_ratelimit())
	111	printk("ip6t_REJECT: Can't alloc skb\n");
	112	dst_release(dst);
	113	return;
	114	}
	115
adf30907	116	skb_dst_set(nskb, dst);
764d8a9f PM	117
	118	skb_reserve(nskb, hh_len + dst->header_len);
	119
1ced98e8 ACM	120	skb_put(nskb, sizeof(struct ipv6hdr));
1ced98e8 ACM	121	skb_reset_network_header(nskb);
0660e03f	122	ip6h = ipv6_hdr(nskb);
764d8a9f PM	123	ip6h->version = 6;
	124	ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT);
	125	ip6h->nexthdr = IPPROTO_TCP;
764d8a9f PM	126	ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr);
	127	ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr);
	128
	129	tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
	130	/* Truncate to length (no data) */
	131	tcph->doff = sizeof(struct tcphdr)/4;
	132	tcph->source = otcph.dest;
	133	tcph->dest = otcph.source;
	134
	135	if (otcph.ack) {
	136	needs_ack = 0;
	137	tcph->seq = otcph.ack_seq;
	138	tcph->ack_seq = 0;
	139	} else {
	140	needs_ack = 1;
	141	tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
	142	+ otcplen - (otcph.doff<<2));
	143	tcph->seq = 0;
	144	}
	145
	146	/* Reset flags */
	147	((u_int8_t *)tcph)[13] = 0;
	148	tcph->rst = 1;
	149	tcph->ack = needs_ack;
	150	tcph->window = 0;
	151	tcph->urg_ptr = 0;
	152	tcph->check = 0;
	153
	154	/* Adjust TCP checksum */
0660e03f ACM	155	tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr,
0660e03f ACM	156	&ipv6_hdr(nskb)->daddr,
764d8a9f	157	sizeof(struct tcphdr), IPPROTO_TCP,
a47362a2	158	csum_partial(tcph,
764d8a9f PM	159	sizeof(struct tcphdr), 0));
764d8a9f PM	160
08857fa7 YK	161	nf_ct_attach(nskb, oldskb);
08857fa7 YK	162
ef76bc23	163	ip6_local_out(nskb);
764d8a9f PM	164	}
	165
	166	static inline void
e10aad99 AD	167	send_unreach(struct net net, struct sk_buff skb_in, unsigned char code,
e10aad99 AD	168	unsigned int hooknum)
764d8a9f	169	{
6e23ae2a	170	if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL)
e10aad99	171	skb_in->dev = net->loopback_dev;
764d8a9f	172
3ffe533c	173	icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0);
764d8a9f PM	174	}
764d8a9f PM	175
d3c5ee6d	176	static unsigned int
7eb35586	177	reject_tg6(struct sk_buff skb, const struct xt_target_param par)
764d8a9f	178	{
7eb35586 JE	179	const struct ip6t_reject_info *reject = par->targinfo;
7eb35586 JE	180	struct net *net = dev_net((par->in != NULL) ? par->in : par->out);
764d8a9f	181
0dc47877	182	pr_debug("%s: medium point\n", __func__);
764d8a9f PM	183	/* WARNING: This code causes reentry within ip6tables.
	184	This means that the ip6tables jump stack is now crap. We
	185	must return an absolute verdict. --RR */
1ab1457c YH	186	switch (reject->with) {
1ab1457c YH	187	case IP6T_ICMP6_NO_ROUTE:
7eb35586	188	send_unreach(net, skb, ICMPV6_NOROUTE, par->hooknum);
1ab1457c YH	189	break;
1ab1457c YH	190	case IP6T_ICMP6_ADM_PROHIBITED:
7eb35586	191	send_unreach(net, skb, ICMPV6_ADM_PROHIBITED, par->hooknum);
1ab1457c YH	192	break;
1ab1457c YH	193	case IP6T_ICMP6_NOT_NEIGHBOUR:
7eb35586	194	send_unreach(net, skb, ICMPV6_NOT_NEIGHBOUR, par->hooknum);
1ab1457c YH	195	break;
1ab1457c YH	196	case IP6T_ICMP6_ADDR_UNREACH:
7eb35586	197	send_unreach(net, skb, ICMPV6_ADDR_UNREACH, par->hooknum);
1ab1457c YH	198	break;
1ab1457c YH	199	case IP6T_ICMP6_PORT_UNREACH:
7eb35586	200	send_unreach(net, skb, ICMPV6_PORT_UNREACH, par->hooknum);
1ab1457c YH	201	break;
1ab1457c YH	202	case IP6T_ICMP6_ECHOREPLY:
764d8a9f PM	203	/* Do nothing */
	204	break;
	205	case IP6T_TCP_RESET:
e10aad99	206	send_reset(net, skb);
764d8a9f PM	207	break;
	208	default:
	209	if (net_ratelimit())
	210	printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with);
	211	break;
	212	}
	213
	214	return NF_DROP;
	215	}
	216
af5d6dc2	217	static bool reject_tg6_check(const struct xt_tgchk_param *par)
764d8a9f	218	{
af5d6dc2 JE	219	const struct ip6t_reject_info *rejinfo = par->targinfo;
af5d6dc2 JE	220	const struct ip6t_entry *e = par->entryinfo;
764d8a9f	221
764d8a9f PM	222	if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
764d8a9f PM	223	printk("ip6t_REJECT: ECHOREPLY is not supported.\n");
e1931b78	224	return false;
764d8a9f PM	225	} else if (rejinfo->with == IP6T_TCP_RESET) {
764d8a9f PM	226	/* Must specify that it's a TCP packet */
3666ed1c JP	227	if (e->ipv6.proto != IPPROTO_TCP \|\|
3666ed1c JP	228	(e->ipv6.invflags & XT_INV_PROTO)) {
0d53778e	229	printk("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
e1931b78	230	return false;
764d8a9f PM	231	}
764d8a9f PM	232	}
e1931b78	233	return true;
764d8a9f PM	234	}
764d8a9f PM	235
d3c5ee6d	236	static struct xt_target reject_tg6_reg __read_mostly = {
764d8a9f	237	.name = "REJECT",
ee999d8b	238	.family = NFPROTO_IPV6,
d3c5ee6d	239	.target = reject_tg6,
7f939713 PM	240	.targetsize = sizeof(struct ip6t_reject_info),
7f939713 PM	241	.table = "filter",
6e23ae2a PM	242	.hooks = (1 << NF_INET_LOCAL_IN) \| (1 << NF_INET_FORWARD) \|
6e23ae2a PM	243	(1 << NF_INET_LOCAL_OUT),
d3c5ee6d	244	.checkentry = reject_tg6_check,
764d8a9f PM	245	.me = THIS_MODULE
	246	};
	247
d3c5ee6d	248	static int __init reject_tg6_init(void)
764d8a9f	249	{
d3c5ee6d	250	return xt_register_target(&reject_tg6_reg);
764d8a9f PM	251	}
764d8a9f PM	252
d3c5ee6d	253	static void __exit reject_tg6_exit(void)
764d8a9f	254	{
d3c5ee6d	255	xt_unregister_target(&reject_tg6_reg);
764d8a9f PM	256	}
764d8a9f PM	257
d3c5ee6d JE	258	module_init(reject_tg6_init);
d3c5ee6d JE	259	module_exit(reject_tg6_exit);