[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_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 = oldskb->nh.ipv6h, *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);

	ip6h = nskb->nh.ipv6h = (struct ipv6hdr *)
					skb_put(nskb, sizeof(struct ipv6hdr));
	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(&nskb->nh.ipv6h->saddr,
				      &nskb->nh.ipv6h->daddr,
				      sizeof(struct tcphdr), IPPROTO_TCP,
				      csum_partial((char *)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,
			   void *userinfo)
{
	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 int check(const char *tablename,
		 const void *entry,
		 const struct xt_target *target,
		 void *targinfo,
		 unsigned int targinfosize,
		 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 0;
	} else if (rejinfo->with == IP6T_TCP_RESET) {
		/* Must specify that it's a TCP packet */
		if (e->ipv6.proto != IPPROTO_TCP
		    || (e->ipv6.invflags & IP6T_INV_PROTO)) {
			DEBUGP("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
			return 0;
		}
	}
	return 1;
}

static struct ip6t_target ip6t_reject_reg = {
	.name		= "REJECT",
	.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)
{
	if (ip6t_register_target(&ip6t_reject_reg))
		return -EINVAL;
	return 0;
}

static void __exit ip6t_reject_fini(void)
{
	ip6t_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>
	29	#include <linux/netfilter_ipv6/ip6_tables.h>
	30	#include <linux/netfilter_ipv6/ip6t_REJECT.h>
	31
	32	MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
	33	MODULE_DESCRIPTION("IP6 tables REJECT target module");
	34	MODULE_LICENSE("GPL");
	35
	36	#if 0
	37	#define DEBUGP printk
	38	#else
	39	#define DEBUGP(format, args...)
	40	#endif
	41
	42	/* Send RST reply */
	43	static void send_reset(struct sk_buff *oldskb)
	44	{
	45	struct sk_buff *nskb;
	46	struct tcphdr otcph, *tcph;
	47	unsigned int otcplen, hh_len;
	48	int tcphoff, needs_ack;
	49	struct ipv6hdr oip6h = oldskb->nh.ipv6h, ip6h;
	50	struct dst_entry *dst = NULL;
	51	u8 proto;
	52	struct flowi fl;
	53
	54	if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) \|\|
	55	(!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
	56	DEBUGP("ip6t_REJECT: addr is not unicast.\n");
	57	return;
	58	}
	59
	60	proto = oip6h->nexthdr;
	61	tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto);
	62
	63	if ((tcphoff < 0) \|\| (tcphoff > oldskb->len)) {
	64	DEBUGP("ip6t_REJECT: Can't get TCP header.\n");
	65	return;
	66	}
	67
	68	otcplen = oldskb->len - tcphoff;
	69
	70	/* IP header checks: fragment, too short. */
	71	if ((proto != IPPROTO_TCP) \|\| (otcplen < sizeof(struct tcphdr))) {
	72	DEBUGP("ip6t_REJECT: proto(%d) != IPPROTO_TCP, or too short. otcplen = %d\n",
	73	proto, otcplen);
	74	return;
	75	}
	76
	77	if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
	78	BUG();
	79
	80	/* No RST for RST. */
	81	if (otcph.rst) {
82	DEBUGP("ip6t_REJECT: RST is set\n");
83	return;
84	}
85
86	/* Check checksum. */
87	if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
88	skb_checksum(oldskb, tcphoff, otcplen, 0))) {
89	DEBUGP("ip6t_REJECT: TCP checksum is invalid\n");
90	return;
91	}
92
93	memset(&fl, 0, sizeof(fl));
94	fl.proto = IPPROTO_TCP;
95	ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr);
96	ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr);
97	fl.fl_ip_sport = otcph.dest;
98	fl.fl_ip_dport = otcph.source;
beb8d13b	99	security_skb_classify_flow(oldskb, &fl);
764d8a9f PM	100	dst = ip6_route_output(NULL, &fl);
	101	if (dst == NULL)
	102	return;
e104411b	103	if (dst->error \|\| xfrm_lookup(&dst, &fl, NULL, 0))
764d8a9f	104	return;
764d8a9f PM	105
	106	hh_len = (dst->dev->hard_header_len + 15)&~15;
	107	nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
	108	+ sizeof(struct tcphdr) + dst->trailer_len,
	109	GFP_ATOMIC);
	110
	111	if (!nskb) {
	112	if (net_ratelimit())
	113	printk("ip6t_REJECT: Can't alloc skb\n");
	114	dst_release(dst);
	115	return;
	116	}
	117
	118	nskb->dst = dst;
	119
	120	skb_reserve(nskb, hh_len + dst->header_len);
	121
	122	ip6h = nskb->nh.ipv6h = (struct ipv6hdr *)
	123	skb_put(nskb, sizeof(struct ipv6hdr));
	124	ip6h->version = 6;
	125	ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT);
	126	ip6h->nexthdr = IPPROTO_TCP;
	127	ip6h->payload_len = htons(sizeof(struct tcphdr));
	128	ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr);
	129	ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr);
	130
	131	tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
	132	/* Truncate to length (no data) */
	133	tcph->doff = sizeof(struct tcphdr)/4;
	134	tcph->source = otcph.dest;
	135	tcph->dest = otcph.source;
	136
	137	if (otcph.ack) {
	138	needs_ack = 0;
	139	tcph->seq = otcph.ack_seq;
	140	tcph->ack_seq = 0;
	141	} else {
	142	needs_ack = 1;
	143	tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
	144	+ otcplen - (otcph.doff<<2));
	145	tcph->seq = 0;
	146	}
	147
	148	/* Reset flags */
	149	((u_int8_t *)tcph)[13] = 0;
	150	tcph->rst = 1;
	151	tcph->ack = needs_ack;
	152	tcph->window = 0;
	153	tcph->urg_ptr = 0;
	154	tcph->check = 0;
	155
	156	/* Adjust TCP checksum */
	157	tcph->check = csum_ipv6_magic(&nskb->nh.ipv6h->saddr,
	158	&nskb->nh.ipv6h->daddr,
	159	sizeof(struct tcphdr), IPPROTO_TCP,
	160	csum_partial((char *)tcph,
	161	sizeof(struct tcphdr), 0));
	162
08857fa7 YK	163	nf_ct_attach(nskb, oldskb);
08857fa7 YK	164
764d8a9f PM	165	NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, nskb, NULL, nskb->dst->dev,
	166	dst_output);
	167	}
	168
	169	static inline void
	170	send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum)
	171	{
	172	if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL)
	173	skb_in->dev = &loopback_dev;
	174
	175	icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL);
	176	}
	177
	178	static unsigned int reject6_target(struct sk_buff **pskb,
	179	const struct net_device *in,
	180	const struct net_device *out,
	181	unsigned int hooknum,
c4986734	182	const struct xt_target *target,
764d8a9f PM	183	const void *targinfo,
	184	void *userinfo)
	185	{
	186	const struct ip6t_reject_info *reject = targinfo;
	187
	188	DEBUGP(KERN_DEBUG "%s: medium point\n", __FUNCTION__);
	189	/* WARNING: This code causes reentry within ip6tables.
	190	This means that the ip6tables jump stack is now crap. We
	191	must return an absolute verdict. --RR */
	192	switch (reject->with) {
	193	case IP6T_ICMP6_NO_ROUTE:
	194	send_unreach(*pskb, ICMPV6_NOROUTE, hooknum);
	195	break;
	196	case IP6T_ICMP6_ADM_PROHIBITED:
	197	send_unreach(*pskb, ICMPV6_ADM_PROHIBITED, hooknum);
	198	break;
	199	case IP6T_ICMP6_NOT_NEIGHBOUR:
	200	send_unreach(*pskb, ICMPV6_NOT_NEIGHBOUR, hooknum);
	201	break;
	202	case IP6T_ICMP6_ADDR_UNREACH:
	203	send_unreach(*pskb, ICMPV6_ADDR_UNREACH, hooknum);
	204	break;
	205	case IP6T_ICMP6_PORT_UNREACH:
	206	send_unreach(*pskb, ICMPV6_PORT_UNREACH, hooknum);
	207	break;
	208	case IP6T_ICMP6_ECHOREPLY:
	209	/* Do nothing */
	210	break;
	211	case IP6T_TCP_RESET:
	212	send_reset(*pskb);
	213	break;
	214	default:
	215	if (net_ratelimit())
	216	printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with);
	217	break;
	218	}
	219
	220	return NF_DROP;
	221	}
	222
	223	static int check(const char *tablename,
2e4e6a17	224	const void *entry,
c4986734	225	const struct xt_target *target,
764d8a9f PM	226	void *targinfo,
	227	unsigned int targinfosize,
	228	unsigned int hook_mask)
	229	{
	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) {
	234	printk("ip6t_REJECT: ECHOREPLY is not supported.\n");
	235	return 0;
	236	} else if (rejinfo->with == IP6T_TCP_RESET) {
	237	/* Must specify that it's a TCP packet */
	238	if (e->ipv6.proto != IPPROTO_TCP
	239	\|\| (e->ipv6.invflags & IP6T_INV_PROTO)) {
	240	DEBUGP("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
	241	return 0;
	242	}
	243	}
764d8a9f PM	244	return 1;
	245	}
	246
	247	static struct ip6t_target ip6t_reject_reg = {
	248	.name = "REJECT",
	249	.target = reject6_target,
7f939713 PM	250	.targetsize = sizeof(struct ip6t_reject_info),
	251	.table = "filter",
	252	.hooks = (1 << NF_IP6_LOCAL_IN) \| (1 << NF_IP6_FORWARD) \|
	253	(1 << NF_IP6_LOCAL_OUT),
764d8a9f PM	254	.checkentry = check,
	255	.me = THIS_MODULE
	256	};
	257
65b4b4e8	258	static int __init ip6t_reject_init(void)
764d8a9f PM	259	{
	260	if (ip6t_register_target(&ip6t_reject_reg))
	261	return -EINVAL;
	262	return 0;
	263	}
	264
65b4b4e8	265	static void __exit ip6t_reject_fini(void)
764d8a9f PM	266	{
	267	ip6t_unregister_target(&ip6t_reject_reg);
	268	}
	269
65b4b4e8 AM	270	module_init(ip6t_reject_init);
65b4b4e8 AM	271	module_exit(ip6t_reject_fini);