[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/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("IP6 tables REJECT target module");
MODULE_LICENSE("GPL");

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

/* Send RST reply */
static void send_reset(struct sk_buff *oldskb)
{
	struct sk_buff *nskb;
	struct tcphdr otcph, *tcph;
	unsigned int otcplen, hh_len;
	int tcphoff, needs_ack;
	struct ipv6hdr *oip6h = ipv6_hdr(oldskb), *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))) {
		DEBUGP("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)) {
		DEBUGP("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))) {
		DEBUGP("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) {
		DEBUGP("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))) {
		DEBUGP("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(NULL, &fl);
	if (dst == NULL)
		return;
	if (dst->error || xfrm_lookup(&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;
	}

	nskb->dst = 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;
	ip6h->payload_len = htons(sizeof(struct tcphdr));
	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);

	NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, nskb, NULL, nskb->dst->dev,
		dst_output);
}

static inline void
send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum)
{
	if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL)
		skb_in->dev = &loopback_dev;

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

static unsigned int reject6_target(struct sk_buff **pskb,
			   const struct net_device *in,
			   const struct net_device *out,
			   unsigned int hooknum,
			   const struct xt_target *target,
			   const void *targinfo)
{
	const struct ip6t_reject_info *reject = targinfo;

	DEBUGP(KERN_DEBUG "%s: medium point\n", __FUNCTION__);
	/* 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(*pskb, ICMPV6_NOROUTE, hooknum);
		break;
	case IP6T_ICMP6_ADM_PROHIBITED:
		send_unreach(*pskb, ICMPV6_ADM_PROHIBITED, hooknum);
		break;
	case IP6T_ICMP6_NOT_NEIGHBOUR:
		send_unreach(*pskb, ICMPV6_NOT_NEIGHBOUR, hooknum);
		break;
	case IP6T_ICMP6_ADDR_UNREACH:
		send_unreach(*pskb, ICMPV6_ADDR_UNREACH, hooknum);
		break;
	case IP6T_ICMP6_PORT_UNREACH:
		send_unreach(*pskb, ICMPV6_PORT_UNREACH, hooknum);
		break;
	case IP6T_ICMP6_ECHOREPLY:
		/* Do nothing */
		break;
	case IP6T_TCP_RESET:
		send_reset(*pskb);
		break;
	default:
		if (net_ratelimit())
			printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with);
		break;
	}

	return NF_DROP;
}

static bool check(const char *tablename,
		  const void *entry,
		  const struct xt_target *target,
		  void *targinfo,
		  unsigned int hook_mask)
{
	const struct ip6t_reject_info *rejinfo = targinfo;
	const struct ip6t_entry *e = entry;

	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)) {
			DEBUGP("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
			return false;
		}
	}
	return true;
}

static struct xt_target ip6t_reject_reg = {
	.name		= "REJECT",
	.family		= AF_INET6,
	.target		= reject6_target,
	.targetsize	= sizeof(struct ip6t_reject_info),
	.table		= "filter",
	.hooks		= (1 << NF_IP6_LOCAL_IN) | (1 << NF_IP6_FORWARD) |
			  (1 << NF_IP6_LOCAL_OUT),
	.checkentry	= check,
	.me		= THIS_MODULE
};

static int __init ip6t_reject_init(void)
{
	return xt_register_target(&ip6t_reject_reg);
}

static void __exit ip6t_reject_fini(void)
{
	xt_unregister_target(&ip6t_reject_reg);
}

module_init(ip6t_reject_init);
module_exit(ip6t_reject_fini);
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
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>");
	34	MODULE_DESCRIPTION("IP6 tables REJECT target module");
	35	MODULE_LICENSE("GPL");
	36
	37	#if 0
	38	#define DEBUGP printk
	39	#else
	40	#define DEBUGP(format, args...)
	41	#endif
	42
	43	/* Send RST reply */
	44	static void send_reset(struct sk_buff *oldskb)
	45	{
	46	struct sk_buff *nskb;
	47	struct tcphdr otcph, *tcph;
	48	unsigned int otcplen, hh_len;
	49	int tcphoff, needs_ack;
0660e03f	50	struct ipv6hdr oip6h = ipv6_hdr(oldskb), ip6h;
764d8a9f PM	51	struct dst_entry *dst = NULL;
	52	u8 proto;
	53	struct flowi fl;
	54
	55	if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) \|\|
	56	(!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
	57	DEBUGP("ip6t_REJECT: addr is not unicast.\n");
	58	return;
	59	}
	60
	61	proto = oip6h->nexthdr;
	62	tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto);
	63
	64	if ((tcphoff < 0) \|\| (tcphoff > oldskb->len)) {
	65	DEBUGP("ip6t_REJECT: Can't get TCP header.\n");
	66	return;
	67	}
	68
	69	otcplen = oldskb->len - tcphoff;
	70
	71	/* IP header checks: fragment, too short. */
	72	if ((proto != IPPROTO_TCP) \|\| (otcplen < sizeof(struct tcphdr))) {
	73	DEBUGP("ip6t_REJECT: proto(%d) != IPPROTO_TCP, or too short. otcplen = %d\n",
	74	proto, otcplen);
	75	return;
	76	}
	77
	78	if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
	79	BUG();
	80
	81	/* No RST for RST. */
	82	if (otcph.rst) {
	83	DEBUGP("ip6t_REJECT: RST is set\n");
	84	return;
	85	}
	86
	87	/* Check checksum. */
	88	if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
	89	skb_checksum(oldskb, tcphoff, otcplen, 0))) {
	90	DEBUGP("ip6t_REJECT: TCP checksum is invalid\n");
	91	return;
	92	}
	93
	94	memset(&fl, 0, sizeof(fl));
	95	fl.proto = IPPROTO_TCP;
	96	ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr);
	97	ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr);
	98	fl.fl_ip_sport = otcph.dest;
	99	fl.fl_ip_dport = otcph.source;
beb8d13b	100	security_skb_classify_flow(oldskb, &fl);
764d8a9f PM	101	dst = ip6_route_output(NULL, &fl);
	102	if (dst == NULL)
	103	return;
e104411b	104	if (dst->error \|\| xfrm_lookup(&dst, &fl, NULL, 0))
764d8a9f	105	return;
764d8a9f PM	106
	107	hh_len = (dst->dev->hard_header_len + 15)&~15;
	108	nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
	109	+ sizeof(struct tcphdr) + dst->trailer_len,
	110	GFP_ATOMIC);
	111
	112	if (!nskb) {
	113	if (net_ratelimit())
	114	printk("ip6t_REJECT: Can't alloc skb\n");
	115	dst_release(dst);
	116	return;
	117	}
	118
	119	nskb->dst = dst;
	120
	121	skb_reserve(nskb, hh_len + dst->header_len);
	122
1ced98e8 ACM	123	skb_put(nskb, sizeof(struct ipv6hdr));
1ced98e8 ACM	124	skb_reset_network_header(nskb);
0660e03f	125	ip6h = ipv6_hdr(nskb);
764d8a9f PM	126	ip6h->version = 6;
	127	ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT);
	128	ip6h->nexthdr = IPPROTO_TCP;
	129	ip6h->payload_len = htons(sizeof(struct tcphdr));
	130	ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr);
	131	ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr);
	132
	133	tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
	134	/* Truncate to length (no data) */
	135	tcph->doff = sizeof(struct tcphdr)/4;
	136	tcph->source = otcph.dest;
	137	tcph->dest = otcph.source;
	138
	139	if (otcph.ack) {
	140	needs_ack = 0;
	141	tcph->seq = otcph.ack_seq;
	142	tcph->ack_seq = 0;
	143	} else {
	144	needs_ack = 1;
	145	tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
	146	+ otcplen - (otcph.doff<<2));
	147	tcph->seq = 0;
	148	}
	149
	150	/* Reset flags */
	151	((u_int8_t *)tcph)[13] = 0;
	152	tcph->rst = 1;
	153	tcph->ack = needs_ack;
	154	tcph->window = 0;
	155	tcph->urg_ptr = 0;
	156	tcph->check = 0;
	157
	158	/* Adjust TCP checksum */
0660e03f ACM	159	tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr,
0660e03f ACM	160	&ipv6_hdr(nskb)->daddr,
764d8a9f	161	sizeof(struct tcphdr), IPPROTO_TCP,
a47362a2	162	csum_partial(tcph,
764d8a9f PM	163	sizeof(struct tcphdr), 0));
764d8a9f PM	164
08857fa7 YK	165	nf_ct_attach(nskb, oldskb);
08857fa7 YK	166
764d8a9f PM	167	NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, nskb, NULL, nskb->dst->dev,
	168	dst_output);
	169	}
	170
	171	static inline void
	172	send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum)
	173	{
	174	if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL)
	175	skb_in->dev = &loopback_dev;
	176
	177	icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL);
	178	}
	179
	180	static unsigned int reject6_target(struct sk_buff **pskb,
	181	const struct net_device *in,
	182	const struct net_device *out,
	183	unsigned int hooknum,
c4986734	184	const struct xt_target *target,
fe1cb108	185	const void *targinfo)
764d8a9f PM	186	{
	187	const struct ip6t_reject_info *reject = targinfo;
	188
	189	DEBUGP(KERN_DEBUG "%s: medium point\n", __FUNCTION__);
	190	/* WARNING: This code causes reentry within ip6tables.
	191	This means that the ip6tables jump stack is now crap. We
	192	must return an absolute verdict. --RR */
1ab1457c YH	193	switch (reject->with) {
	194	case IP6T_ICMP6_NO_ROUTE:
	195	send_unreach(*pskb, ICMPV6_NOROUTE, hooknum);
	196	break;
	197	case IP6T_ICMP6_ADM_PROHIBITED:
	198	send_unreach(*pskb, ICMPV6_ADM_PROHIBITED, hooknum);
	199	break;
	200	case IP6T_ICMP6_NOT_NEIGHBOUR:
	201	send_unreach(*pskb, ICMPV6_NOT_NEIGHBOUR, hooknum);
	202	break;
	203	case IP6T_ICMP6_ADDR_UNREACH:
	204	send_unreach(*pskb, ICMPV6_ADDR_UNREACH, hooknum);
	205	break;
	206	case IP6T_ICMP6_PORT_UNREACH:
	207	send_unreach(*pskb, ICMPV6_PORT_UNREACH, hooknum);
	208	break;
	209	case IP6T_ICMP6_ECHOREPLY:
764d8a9f PM	210	/* Do nothing */
	211	break;
	212	case IP6T_TCP_RESET:
	213	send_reset(*pskb);
	214	break;
	215	default:
	216	if (net_ratelimit())
	217	printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with);
	218	break;
	219	}
	220
	221	return NF_DROP;
	222	}
	223
e1931b78 JE	224	static bool check(const char *tablename,
	225	const void *entry,
	226	const struct xt_target *target,
	227	void *targinfo,
	228	unsigned int hook_mask)
764d8a9f	229	{
1ab1457c	230	const struct ip6t_reject_info *rejinfo = targinfo;
2e4e6a17	231	const struct ip6t_entry *e = entry;
764d8a9f	232
764d8a9f PM	233	if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
764d8a9f PM	234	printk("ip6t_REJECT: ECHOREPLY is not supported.\n");
e1931b78	235	return false;
764d8a9f PM	236	} else if (rejinfo->with == IP6T_TCP_RESET) {
	237	/* Must specify that it's a TCP packet */
	238	if (e->ipv6.proto != IPPROTO_TCP
6709dbbb	239	\|\| (e->ipv6.invflags & XT_INV_PROTO)) {
764d8a9f	240	DEBUGP("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
e1931b78	241	return false;
764d8a9f PM	242	}
764d8a9f PM	243	}
e1931b78	244	return true;
764d8a9f PM	245	}
764d8a9f PM	246
6709dbbb	247	static struct xt_target ip6t_reject_reg = {
764d8a9f	248	.name = "REJECT",
6709dbbb	249	.family = AF_INET6,
764d8a9f	250	.target = reject6_target,
7f939713 PM	251	.targetsize = sizeof(struct ip6t_reject_info),
	252	.table = "filter",
	253	.hooks = (1 << NF_IP6_LOCAL_IN) \| (1 << NF_IP6_FORWARD) \|
	254	(1 << NF_IP6_LOCAL_OUT),
764d8a9f PM	255	.checkentry = check,
	256	.me = THIS_MODULE
	257	};
	258
65b4b4e8	259	static int __init ip6t_reject_init(void)
764d8a9f	260	{
6709dbbb	261	return xt_register_target(&ip6t_reject_reg);
764d8a9f PM	262	}
764d8a9f PM	263
65b4b4e8	264	static void __exit ip6t_reject_fini(void)
764d8a9f	265	{
6709dbbb	266	xt_unregister_target(&ip6t_reject_reg);
764d8a9f PM	267	}
764d8a9f PM	268
65b4b4e8 AM	269	module_init(ip6t_reject_init);
65b4b4e8 AM	270	module_exit(ip6t_reject_fini);