[linux-2.6-block.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");

/* 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))) {
		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(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;
	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 sk_buff *skb_in, unsigned char code, unsigned int hooknum)
{
	if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL)
		skb_in->dev = init_net.loopback_dev;

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

static unsigned int
reject_tg6(struct sk_buff *skb, 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;

	pr_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(skb, ICMPV6_NOROUTE, hooknum);
		break;
	case IP6T_ICMP6_ADM_PROHIBITED:
		send_unreach(skb, ICMPV6_ADM_PROHIBITED, hooknum);
		break;
	case IP6T_ICMP6_NOT_NEIGHBOUR:
		send_unreach(skb, ICMPV6_NOT_NEIGHBOUR, hooknum);
		break;
	case IP6T_ICMP6_ADDR_UNREACH:
		send_unreach(skb, ICMPV6_ADDR_UNREACH, hooknum);
		break;
	case IP6T_ICMP6_PORT_UNREACH:
		send_unreach(skb, ICMPV6_PORT_UNREACH, hooknum);
		break;
	case IP6T_ICMP6_ECHOREPLY:
		/* Do nothing */
		break;
	case IP6T_TCP_RESET:
		send_reset(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 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)) {
			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		= AF_INET6,
	.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
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
764d8a9f PM	37	/* Send RST reply */
	38	static void send_reset(struct sk_buff *oldskb)
	39	{
	40	struct sk_buff *nskb;
	41	struct tcphdr otcph, *tcph;
	42	unsigned int otcplen, hh_len;
	43	int tcphoff, needs_ack;
0660e03f	44	struct ipv6hdr oip6h = ipv6_hdr(oldskb), ip6h;
764d8a9f PM	45	struct dst_entry *dst = NULL;
	46	u8 proto;
	47	struct flowi fl;
	48
	49	if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) \|\|
	50	(!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
0d53778e	51	pr_debug("ip6t_REJECT: addr is not unicast.\n");
764d8a9f PM	52	return;
	53	}
	54
	55	proto = oip6h->nexthdr;
	56	tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto);
	57
	58	if ((tcphoff < 0) \|\| (tcphoff > oldskb->len)) {
0d53778e	59	pr_debug("ip6t_REJECT: Can't get TCP header.\n");
764d8a9f PM	60	return;
	61	}
	62
	63	otcplen = oldskb->len - tcphoff;
	64
	65	/* IP header checks: fragment, too short. */
7c4e36bc	66	if (proto != IPPROTO_TCP \|\| otcplen < sizeof(struct tcphdr)) {
0d53778e PM	67	pr_debug("ip6t_REJECT: proto(%d) != IPPROTO_TCP, "
	68	"or too short. otcplen = %d\n",
	69	proto, otcplen);
764d8a9f PM	70	return;
	71	}
	72
	73	if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
	74	BUG();
	75
	76	/* No RST for RST. */
	77	if (otcph.rst) {
0d53778e	78	pr_debug("ip6t_REJECT: RST is set\n");
764d8a9f PM	79	return;
	80	}
	81
	82	/* Check checksum. */
	83	if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
	84	skb_checksum(oldskb, tcphoff, otcplen, 0))) {
0d53778e	85	pr_debug("ip6t_REJECT: TCP checksum is invalid\n");
764d8a9f PM	86	return;
	87	}
	88
	89	memset(&fl, 0, sizeof(fl));
	90	fl.proto = IPPROTO_TCP;
	91	ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr);
	92	ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr);
	93	fl.fl_ip_sport = otcph.dest;
	94	fl.fl_ip_dport = otcph.source;
beb8d13b	95	security_skb_classify_flow(oldskb, &fl);
764d8a9f PM	96	dst = ip6_route_output(NULL, &fl);
	97	if (dst == NULL)
	98	return;
e104411b	99	if (dst->error \|\| xfrm_lookup(&dst, &fl, NULL, 0))
764d8a9f	100	return;
764d8a9f PM	101
	102	hh_len = (dst->dev->hard_header_len + 15)&~15;
	103	nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
	104	+ sizeof(struct tcphdr) + dst->trailer_len,
	105	GFP_ATOMIC);
	106
	107	if (!nskb) {
	108	if (net_ratelimit())
	109	printk("ip6t_REJECT: Can't alloc skb\n");
	110	dst_release(dst);
	111	return;
	112	}
	113
	114	nskb->dst = dst;
	115
	116	skb_reserve(nskb, hh_len + dst->header_len);
	117
1ced98e8 ACM	118	skb_put(nskb, sizeof(struct ipv6hdr));
1ced98e8 ACM	119	skb_reset_network_header(nskb);
0660e03f	120	ip6h = ipv6_hdr(nskb);
764d8a9f PM	121	ip6h->version = 6;
	122	ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT);
	123	ip6h->nexthdr = IPPROTO_TCP;
764d8a9f PM	124	ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr);
	125	ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr);
	126
	127	tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
	128	/* Truncate to length (no data) */
	129	tcph->doff = sizeof(struct tcphdr)/4;
	130	tcph->source = otcph.dest;
	131	tcph->dest = otcph.source;
	132
	133	if (otcph.ack) {
	134	needs_ack = 0;
	135	tcph->seq = otcph.ack_seq;
	136	tcph->ack_seq = 0;
	137	} else {
	138	needs_ack = 1;
	139	tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
	140	+ otcplen - (otcph.doff<<2));
	141	tcph->seq = 0;
	142	}
	143
	144	/* Reset flags */
	145	((u_int8_t *)tcph)[13] = 0;
	146	tcph->rst = 1;
	147	tcph->ack = needs_ack;
	148	tcph->window = 0;
	149	tcph->urg_ptr = 0;
	150	tcph->check = 0;
	151
	152	/* Adjust TCP checksum */
0660e03f ACM	153	tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr,
0660e03f ACM	154	&ipv6_hdr(nskb)->daddr,
764d8a9f	155	sizeof(struct tcphdr), IPPROTO_TCP,
a47362a2	156	csum_partial(tcph,
764d8a9f PM	157	sizeof(struct tcphdr), 0));
764d8a9f PM	158
08857fa7 YK	159	nf_ct_attach(nskb, oldskb);
08857fa7 YK	160
ef76bc23	161	ip6_local_out(nskb);
764d8a9f PM	162	}
	163
	164	static inline void
	165	send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum)
	166	{
6e23ae2a	167	if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL)
2774c7ab	168	skb_in->dev = init_net.loopback_dev;
764d8a9f PM	169
	170	icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL);
	171	}
	172
d3c5ee6d JE	173	static unsigned int
	174	reject_tg6(struct sk_buff skb, const struct net_device in,
	175	const struct net_device *out, unsigned int hooknum,
	176	const struct xt_target target, const void targinfo)
764d8a9f PM	177	{
	178	const struct ip6t_reject_info *reject = targinfo;
	179
0d53778e	180	pr_debug("%s: medium point\n", __FUNCTION__);
764d8a9f PM	181	/* WARNING: This code causes reentry within ip6tables.
	182	This means that the ip6tables jump stack is now crap. We
	183	must return an absolute verdict. --RR */
1ab1457c YH	184	switch (reject->with) {
1ab1457c YH	185	case IP6T_ICMP6_NO_ROUTE:
3db05fea	186	send_unreach(skb, ICMPV6_NOROUTE, hooknum);
1ab1457c YH	187	break;
1ab1457c YH	188	case IP6T_ICMP6_ADM_PROHIBITED:
3db05fea	189	send_unreach(skb, ICMPV6_ADM_PROHIBITED, hooknum);
1ab1457c YH	190	break;
1ab1457c YH	191	case IP6T_ICMP6_NOT_NEIGHBOUR:
3db05fea	192	send_unreach(skb, ICMPV6_NOT_NEIGHBOUR, hooknum);
1ab1457c YH	193	break;
1ab1457c YH	194	case IP6T_ICMP6_ADDR_UNREACH:
3db05fea	195	send_unreach(skb, ICMPV6_ADDR_UNREACH, hooknum);
1ab1457c YH	196	break;
1ab1457c YH	197	case IP6T_ICMP6_PORT_UNREACH:
3db05fea	198	send_unreach(skb, ICMPV6_PORT_UNREACH, hooknum);
1ab1457c YH	199	break;
1ab1457c YH	200	case IP6T_ICMP6_ECHOREPLY:
764d8a9f PM	201	/* Do nothing */
	202	break;
	203	case IP6T_TCP_RESET:
3db05fea	204	send_reset(skb);
764d8a9f PM	205	break;
	206	default:
	207	if (net_ratelimit())
	208	printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with);
	209	break;
	210	}
	211
	212	return NF_DROP;
	213	}
	214
d3c5ee6d JE	215	static bool
	216	reject_tg6_check(const char tablename, const void entry,
	217	const struct xt_target target, void targinfo,
	218	unsigned int hook_mask)
764d8a9f	219	{
1ab1457c	220	const struct ip6t_reject_info *rejinfo = targinfo;
2e4e6a17	221	const struct ip6t_entry *e = entry;
764d8a9f	222
764d8a9f PM	223	if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
764d8a9f PM	224	printk("ip6t_REJECT: ECHOREPLY is not supported.\n");
e1931b78	225	return false;
764d8a9f PM	226	} else if (rejinfo->with == IP6T_TCP_RESET) {
	227	/* Must specify that it's a TCP packet */
	228	if (e->ipv6.proto != IPPROTO_TCP
6709dbbb	229	\|\| (e->ipv6.invflags & XT_INV_PROTO)) {
0d53778e	230	printk("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
e1931b78	231	return false;
764d8a9f PM	232	}
764d8a9f PM	233	}
e1931b78	234	return true;
764d8a9f PM	235	}
764d8a9f PM	236
d3c5ee6d	237	static struct xt_target reject_tg6_reg __read_mostly = {
764d8a9f	238	.name = "REJECT",
6709dbbb	239	.family = AF_INET6,
d3c5ee6d	240	.target = reject_tg6,
7f939713 PM	241	.targetsize = sizeof(struct ip6t_reject_info),
7f939713 PM	242	.table = "filter",
6e23ae2a PM	243	.hooks = (1 << NF_INET_LOCAL_IN) \| (1 << NF_INET_FORWARD) \|
6e23ae2a PM	244	(1 << NF_INET_LOCAL_OUT),
d3c5ee6d	245	.checkentry = reject_tg6_check,
764d8a9f PM	246	.me = THIS_MODULE
	247	};
	248
d3c5ee6d	249	static int __init reject_tg6_init(void)
764d8a9f	250	{
d3c5ee6d	251	return xt_register_target(&reject_tg6_reg);
764d8a9f PM	252	}
764d8a9f PM	253
d3c5ee6d	254	static void __exit reject_tg6_exit(void)
764d8a9f	255	{
d3c5ee6d	256	xt_unregister_target(&reject_tg6_reg);
764d8a9f PM	257	}
764d8a9f PM	258
d3c5ee6d JE	259	module_init(reject_tg6_init);
d3c5ee6d JE	260	module_exit(reject_tg6_exit);