[GitHub/mt8127/android_kernel_alcatel_ttab.git] / net / ipv4 / netfilter / ipt_REJECT.c

/*
 * This is a module which is used for rejecting packets.
 * Added support for customized reject packets (Jozsef Kadlecsik).
 * Added support for ICMP type-3-code-13 (Maciej Soltysiak). [RFC 1812]
 */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/icmp.h>
#include <net/icmp.h>
#include <net/ip.h>
#include <net/tcp.h>
#include <net/route.h>
#include <net/dst.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_REJECT.h>
#ifdef CONFIG_BRIDGE_NETFILTER
#include <linux/netfilter_bridge.h>
#endif

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("iptables REJECT target module");

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

static inline struct rtable *route_reverse(struct sk_buff *skb, 
					   struct tcphdr *tcph, int hook)
{
	struct iphdr *iph = skb->nh.iph;
	struct dst_entry *odst;
	struct flowi fl = {};
	struct rtable *rt;

	/* We don't require ip forwarding to be enabled to be able to
	 * send a RST reply for bridged traffic. */
	if (hook != NF_IP_FORWARD
#ifdef CONFIG_BRIDGE_NETFILTER
	    || (skb->nf_bridge && skb->nf_bridge->mask & BRNF_BRIDGED)
#endif
	   ) {
		fl.nl_u.ip4_u.daddr = iph->saddr;
		if (hook == NF_IP_LOCAL_IN)
			fl.nl_u.ip4_u.saddr = iph->daddr;
		fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);

		if (ip_route_output_key(&rt, &fl) != 0)
			return NULL;
	} else {
		/* non-local src, find valid iif to satisfy
		 * rp-filter when calling ip_route_input. */
		fl.nl_u.ip4_u.daddr = iph->daddr;
		if (ip_route_output_key(&rt, &fl) != 0)
			return NULL;

		odst = skb->dst;
		if (ip_route_input(skb, iph->saddr, iph->daddr,
		                   RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
			dst_release(&rt->u.dst);
			return NULL;
		}
		dst_release(&rt->u.dst);
		rt = (struct rtable *)skb->dst;
		skb->dst = odst;

		fl.nl_u.ip4_u.daddr = iph->saddr;
		fl.nl_u.ip4_u.saddr = iph->daddr;
		fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
	}

	if (rt->u.dst.error) {
		dst_release(&rt->u.dst);
		return NULL;
	}

	fl.proto = IPPROTO_TCP;
	fl.fl_ip_sport = tcph->dest;
	fl.fl_ip_dport = tcph->source;
	security_skb_classify_flow(skb, &fl);

	xfrm_lookup((struct dst_entry **)&rt, &fl, NULL, 0);

	return rt;
}

/* Send RST reply */
static void send_reset(struct sk_buff *oldskb, int hook)
{
	struct sk_buff *nskb;
	struct iphdr *iph = oldskb->nh.iph;
	struct tcphdr _otcph, *oth, *tcph;
	struct rtable *rt;
	__be16 tmp_port;
	__be32 tmp_addr;
	int needs_ack;
	int hh_len;

	/* IP header checks: fragment. */
	if (oldskb->nh.iph->frag_off & htons(IP_OFFSET))
		return;

	oth = skb_header_pointer(oldskb, oldskb->nh.iph->ihl * 4,
				 sizeof(_otcph), &_otcph);
	if (oth == NULL)
 		return;

	/* No RST for RST. */
	if (oth->rst)
		return;

	/* Check checksum */
	if (nf_ip_checksum(oldskb, hook, iph->ihl * 4, IPPROTO_TCP))
		return;

	if ((rt = route_reverse(oldskb, oth, hook)) == NULL)
		return;

	hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);

	/* We need a linear, writeable skb.  We also need to expand
	   headroom in case hh_len of incoming interface < hh_len of
	   outgoing interface */
	nskb = skb_copy_expand(oldskb, hh_len, skb_tailroom(oldskb),
			       GFP_ATOMIC);
	if (!nskb) {
		dst_release(&rt->u.dst);
		return;
	}

	dst_release(nskb->dst);
	nskb->dst = &rt->u.dst;

	/* This packet will not be the same as the other: clear nf fields */
	nf_reset(nskb);
	nskb->nfmark = 0;
	skb_init_secmark(nskb);

	tcph = (struct tcphdr *)((u_int32_t*)nskb->nh.iph + nskb->nh.iph->ihl);

	/* Swap source and dest */
	tmp_addr = nskb->nh.iph->saddr;
	nskb->nh.iph->saddr = nskb->nh.iph->daddr;
	nskb->nh.iph->daddr = tmp_addr;
	tmp_port = tcph->source;
	tcph->source = tcph->dest;
	tcph->dest = tmp_port;

	/* Truncate to length (no data) */
	tcph->doff = sizeof(struct tcphdr)/4;
	skb_trim(nskb, nskb->nh.iph->ihl*4 + sizeof(struct tcphdr));
	nskb->nh.iph->tot_len = htons(nskb->len);

	if (tcph->ack) {
		needs_ack = 0;
		tcph->seq = oth->ack_seq;
		tcph->ack_seq = 0;
	} else {
		needs_ack = 1;
		tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin
				      + oldskb->len - oldskb->nh.iph->ihl*4
				      - (oth->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;

	/* Adjust TCP checksum */
	nskb->ip_summed = CHECKSUM_NONE;
	tcph->check = 0;
	tcph->check = tcp_v4_check(tcph, sizeof(struct tcphdr),
				   nskb->nh.iph->saddr,
				   nskb->nh.iph->daddr,
				   csum_partial((char *)tcph,
						sizeof(struct tcphdr), 0));

	/* Adjust IP TTL, DF */
	nskb->nh.iph->ttl = dst_metric(nskb->dst, RTAX_HOPLIMIT);
	/* Set DF, id = 0 */
	nskb->nh.iph->frag_off = htons(IP_DF);
	nskb->nh.iph->id = 0;

	/* Adjust IP checksum */
	nskb->nh.iph->check = 0;
	nskb->nh.iph->check = ip_fast_csum((unsigned char *)nskb->nh.iph, 
					   nskb->nh.iph->ihl);

	/* "Never happens" */
	if (nskb->len > dst_mtu(nskb->dst))
		goto free_nskb;

	nf_ct_attach(nskb, oldskb);

	NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, nskb, NULL, nskb->dst->dev,
		dst_output);
	return;

 free_nskb:
	kfree_skb(nskb);
}

static inline void send_unreach(struct sk_buff *skb_in, int code)
{
	icmp_send(skb_in, ICMP_DEST_UNREACH, code, 0);
}	

static unsigned int reject(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 ipt_reject_info *reject = targinfo;

	/* Our naive response construction doesn't deal with IP
           options, and probably shouldn't try. */
	if ((*pskb)->nh.iph->ihl<<2 != sizeof(struct iphdr))
		return NF_DROP;

	/* WARNING: This code causes reentry within iptables.
	   This means that the iptables jump stack is now crap.  We
	   must return an absolute verdict. --RR */
    	switch (reject->with) {
    	case IPT_ICMP_NET_UNREACHABLE:
    		send_unreach(*pskb, ICMP_NET_UNREACH);
    		break;
    	case IPT_ICMP_HOST_UNREACHABLE:
    		send_unreach(*pskb, ICMP_HOST_UNREACH);
    		break;
    	case IPT_ICMP_PROT_UNREACHABLE:
    		send_unreach(*pskb, ICMP_PROT_UNREACH);
    		break;
    	case IPT_ICMP_PORT_UNREACHABLE:
    		send_unreach(*pskb, ICMP_PORT_UNREACH);
    		break;
    	case IPT_ICMP_NET_PROHIBITED:
    		send_unreach(*pskb, ICMP_NET_ANO);
    		break;
	case IPT_ICMP_HOST_PROHIBITED:
    		send_unreach(*pskb, ICMP_HOST_ANO);
    		break;
    	case IPT_ICMP_ADMIN_PROHIBITED:
		send_unreach(*pskb, ICMP_PKT_FILTERED);
		break;
	case IPT_TCP_RESET:
		send_reset(*pskb, hooknum);
	case IPT_ICMP_ECHOREPLY:
		/* Doesn't happen. */
		break;
	}

	return NF_DROP;
}

static int check(const char *tablename,
		 const void *e_void,
		 const struct xt_target *target,
		 void *targinfo,
		 unsigned int hook_mask)
{
 	const struct ipt_reject_info *rejinfo = targinfo;
	const struct ipt_entry *e = e_void;

	if (rejinfo->with == IPT_ICMP_ECHOREPLY) {
		printk("REJECT: ECHOREPLY no longer supported.\n");
		return 0;
	} else if (rejinfo->with == IPT_TCP_RESET) {
		/* Must specify that it's a TCP packet */
		if (e->ip.proto != IPPROTO_TCP
		    || (e->ip.invflags & IPT_INV_PROTO)) {
			DEBUGP("REJECT: TCP_RESET invalid for non-tcp\n");
			return 0;
		}
	}
	return 1;
}

static struct ipt_target ipt_reject_reg = {
	.name		= "REJECT",
	.target		= reject,
	.targetsize	= sizeof(struct ipt_reject_info),
	.table		= "filter",
	.hooks		= (1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) |
			  (1 << NF_IP_LOCAL_OUT),
	.checkentry	= check,
	.me		= THIS_MODULE,
};

static int __init ipt_reject_init(void)
{
	return ipt_register_target(&ipt_reject_reg);
}

static void __exit ipt_reject_fini(void)
{
	ipt_unregister_target(&ipt_reject_reg);
}

module_init(ipt_reject_init);
module_exit(ipt_reject_fini);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* This is a module which is used for rejecting packets.
	3	* Added support for customized reject packets (Jozsef Kadlecsik).
	4	* Added support for ICMP type-3-code-13 (Maciej Soltysiak). [RFC 1812]
	5	*/
	6
	7	/* (C) 1999-2001 Paul `Rusty' Russell
	8	* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
	9	*
	10	* This program is free software; you can redistribute it and/or modify
	11	* it under the terms of the GNU General Public License version 2 as
	12	* published by the Free Software Foundation.
	13	*/
	14
1da177e4 LT	15	#include <linux/module.h>
	16	#include <linux/skbuff.h>
	17	#include <linux/ip.h>
	18	#include <linux/udp.h>
	19	#include <linux/icmp.h>
	20	#include <net/icmp.h>
	21	#include <net/ip.h>
	22	#include <net/tcp.h>
	23	#include <net/route.h>
	24	#include <net/dst.h>
	25	#include <linux/netfilter_ipv4/ip_tables.h>
	26	#include <linux/netfilter_ipv4/ipt_REJECT.h>
	27	#ifdef CONFIG_BRIDGE_NETFILTER
	28	#include <linux/netfilter_bridge.h>
	29	#endif
	30
	31	MODULE_LICENSE("GPL");
	32	MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
	33	MODULE_DESCRIPTION("iptables REJECT target module");
	34
	35	#if 0
	36	#define DEBUGP printk
	37	#else
	38	#define DEBUGP(format, args...)
	39	#endif
	40
	41	static inline struct rtable route_reverse(struct sk_buff skb,
	42	struct tcphdr *tcph, int hook)
	43	{
	44	struct iphdr *iph = skb->nh.iph;
	45	struct dst_entry *odst;
	46	struct flowi fl = {};
	47	struct rtable *rt;
	48
	49	/* We don't require ip forwarding to be enabled to be able to
	50	* send a RST reply for bridged traffic. */
	51	if (hook != NF_IP_FORWARD
	52	#ifdef CONFIG_BRIDGE_NETFILTER
	53	\|\| (skb->nf_bridge && skb->nf_bridge->mask & BRNF_BRIDGED)
	54	#endif
	55	) {
	56	fl.nl_u.ip4_u.daddr = iph->saddr;
	57	if (hook == NF_IP_LOCAL_IN)
	58	fl.nl_u.ip4_u.saddr = iph->daddr;
	59	fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
	60
	61	if (ip_route_output_key(&rt, &fl) != 0)
	62	return NULL;
	63	} else {
	64	/* non-local src, find valid iif to satisfy
	65	* rp-filter when calling ip_route_input. */
	66	fl.nl_u.ip4_u.daddr = iph->daddr;
	67	if (ip_route_output_key(&rt, &fl) != 0)
	68	return NULL;
	69
	70	odst = skb->dst;
	71	if (ip_route_input(skb, iph->saddr, iph->daddr,
	72	RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
	73	dst_release(&rt->u.dst);
	74	return NULL;
	75	}
	76	dst_release(&rt->u.dst);
	77	rt = (struct rtable *)skb->dst;
	78	skb->dst = odst;
79
80	fl.nl_u.ip4_u.daddr = iph->saddr;
81	fl.nl_u.ip4_u.saddr = iph->daddr;
82	fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
83	}
84
85	if (rt->u.dst.error) {
86	dst_release(&rt->u.dst);
87	return NULL;
88	}
89
90	fl.proto = IPPROTO_TCP;
91	fl.fl_ip_sport = tcph->dest;
92	fl.fl_ip_dport = tcph->source;
beb8d13b	93	security_skb_classify_flow(skb, &fl);
1da177e4	94
e104411b	95	xfrm_lookup((struct dst_entry **)&rt, &fl, NULL, 0);
1da177e4 LT	96
	97	return rt;
	98	}
	99
	100	/* Send RST reply */
	101	static void send_reset(struct sk_buff *oldskb, int hook)
	102	{
	103	struct sk_buff *nskb;
6150bacf	104	struct iphdr *iph = oldskb->nh.iph;
1da177e4 LT	105	struct tcphdr _otcph, oth, tcph;
1da177e4 LT	106	struct rtable *rt;
6a19d614 AV	107	__be16 tmp_port;
6a19d614 AV	108	__be32 tmp_addr;
1da177e4 LT	109	int needs_ack;
	110	int hh_len;
	111
	112	/* IP header checks: fragment. */
	113	if (oldskb->nh.iph->frag_off & htons(IP_OFFSET))
	114	return;
	115
	116	oth = skb_header_pointer(oldskb, oldskb->nh.iph->ihl * 4,
	117	sizeof(_otcph), &_otcph);
	118	if (oth == NULL)
	119	return;
	120
	121	/* No RST for RST. */
	122	if (oth->rst)
	123	return;
	124
6150bacf	125	/* Check checksum */
96f6bf82	126	if (nf_ip_checksum(oldskb, hook, iph->ihl * 4, IPPROTO_TCP))
6150bacf PM	127	return;
6150bacf PM	128
1da177e4 LT	129	if ((rt = route_reverse(oldskb, oth, hook)) == NULL)
	130	return;
	131
	132	hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
	133
	134	/* We need a linear, writeable skb. We also need to expand
	135	headroom in case hh_len of incoming interface < hh_len of
	136	outgoing interface */
	137	nskb = skb_copy_expand(oldskb, hh_len, skb_tailroom(oldskb),
	138	GFP_ATOMIC);
	139	if (!nskb) {
	140	dst_release(&rt->u.dst);
	141	return;
	142	}
	143
	144	dst_release(nskb->dst);
	145	nskb->dst = &rt->u.dst;
	146
	147	/* This packet will not be the same as the other: clear nf fields */
	148	nf_reset(nskb);
1da177e4	149	nskb->nfmark = 0;
984bc16c	150	skb_init_secmark(nskb);
1da177e4 LT	151
	152	tcph = (struct tcphdr )((u_int32_t)nskb->nh.iph + nskb->nh.iph->ihl);
	153
	154	/* Swap source and dest */
	155	tmp_addr = nskb->nh.iph->saddr;
	156	nskb->nh.iph->saddr = nskb->nh.iph->daddr;
	157	nskb->nh.iph->daddr = tmp_addr;
	158	tmp_port = tcph->source;
	159	tcph->source = tcph->dest;
	160	tcph->dest = tmp_port;
	161
	162	/* Truncate to length (no data) */
	163	tcph->doff = sizeof(struct tcphdr)/4;
	164	skb_trim(nskb, nskb->nh.iph->ihl*4 + sizeof(struct tcphdr));
	165	nskb->nh.iph->tot_len = htons(nskb->len);
	166
	167	if (tcph->ack) {
	168	needs_ack = 0;
	169	tcph->seq = oth->ack_seq;
	170	tcph->ack_seq = 0;
	171	} else {
	172	needs_ack = 1;
	173	tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin
	174	+ oldskb->len - oldskb->nh.iph->ihl*4
	175	- (oth->doff<<2));
	176	tcph->seq = 0;
	177	}
	178
	179	/* Reset flags */
	180	((u_int8_t *)tcph)[13] = 0;
	181	tcph->rst = 1;
	182	tcph->ack = needs_ack;
	183
	184	tcph->window = 0;
	185	tcph->urg_ptr = 0;
	186
	187	/* Adjust TCP checksum */
4cf411de	188	nskb->ip_summed = CHECKSUM_NONE;
1da177e4 LT	189	tcph->check = 0;
	190	tcph->check = tcp_v4_check(tcph, sizeof(struct tcphdr),
	191	nskb->nh.iph->saddr,
	192	nskb->nh.iph->daddr,
	193	csum_partial((char *)tcph,
	194	sizeof(struct tcphdr), 0));
	195
	196	/* Adjust IP TTL, DF */
e8eaedf2	197	nskb->nh.iph->ttl = dst_metric(nskb->dst, RTAX_HOPLIMIT);
1da177e4 LT	198	/* Set DF, id = 0 */
	199	nskb->nh.iph->frag_off = htons(IP_DF);
	200	nskb->nh.iph->id = 0;
	201
	202	/* Adjust IP checksum */
	203	nskb->nh.iph->check = 0;
	204	nskb->nh.iph->check = ip_fast_csum((unsigned char *)nskb->nh.iph,
	205	nskb->nh.iph->ihl);
	206
	207	/* "Never happens" */
	208	if (nskb->len > dst_mtu(nskb->dst))
	209	goto free_nskb;
	210
	211	nf_ct_attach(nskb, oldskb);
	212
	213	NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, nskb, NULL, nskb->dst->dev,
	214	dst_output);
	215	return;
	216
	217	free_nskb:
	218	kfree_skb(nskb);
	219	}
	220
	221	static inline void send_unreach(struct sk_buff *skb_in, int code)
	222	{
	223	icmp_send(skb_in, ICMP_DEST_UNREACH, code, 0);
	224	}
	225
	226	static unsigned int reject(struct sk_buff **pskb,
	227	const struct net_device *in,
	228	const struct net_device *out,
	229	unsigned int hooknum,
c4986734	230	const struct xt_target *target,
fe1cb108	231	const void *targinfo)
1da177e4 LT	232	{
	233	const struct ipt_reject_info *reject = targinfo;
	234
	235	/* Our naive response construction doesn't deal with IP
	236	options, and probably shouldn't try. */
	237	if ((*pskb)->nh.iph->ihl<<2 != sizeof(struct iphdr))
	238	return NF_DROP;
	239
	240	/* WARNING: This code causes reentry within iptables.
	241	This means that the iptables jump stack is now crap. We
	242	must return an absolute verdict. --RR */
	243	switch (reject->with) {
	244	case IPT_ICMP_NET_UNREACHABLE:
	245	send_unreach(*pskb, ICMP_NET_UNREACH);
	246	break;
	247	case IPT_ICMP_HOST_UNREACHABLE:
	248	send_unreach(*pskb, ICMP_HOST_UNREACH);
	249	break;
	250	case IPT_ICMP_PROT_UNREACHABLE:
	251	send_unreach(*pskb, ICMP_PROT_UNREACH);
	252	break;
	253	case IPT_ICMP_PORT_UNREACHABLE:
	254	send_unreach(*pskb, ICMP_PORT_UNREACH);
	255	break;
	256	case IPT_ICMP_NET_PROHIBITED:
	257	send_unreach(*pskb, ICMP_NET_ANO);
	258	break;
	259	case IPT_ICMP_HOST_PROHIBITED:
	260	send_unreach(*pskb, ICMP_HOST_ANO);
	261	break;
	262	case IPT_ICMP_ADMIN_PROHIBITED:
	263	send_unreach(*pskb, ICMP_PKT_FILTERED);
	264	break;
	265	case IPT_TCP_RESET:
	266	send_reset(*pskb, hooknum);
	267	case IPT_ICMP_ECHOREPLY:
	268	/* Doesn't happen. */
	269	break;
	270	}
	271
	272	return NF_DROP;
	273	}
	274
	275	static int check(const char *tablename,
2e4e6a17	276	const void *e_void,
c4986734	277	const struct xt_target *target,
1da177e4	278	void *targinfo,
1da177e4 LT	279	unsigned int hook_mask)
	280	{
	281	const struct ipt_reject_info *rejinfo = targinfo;
2e4e6a17	282	const struct ipt_entry *e = e_void;
1da177e4	283
1da177e4 LT	284	if (rejinfo->with == IPT_ICMP_ECHOREPLY) {
	285	printk("REJECT: ECHOREPLY no longer supported.\n");
	286	return 0;
	287	} else if (rejinfo->with == IPT_TCP_RESET) {
	288	/* Must specify that it's a TCP packet */
	289	if (e->ip.proto != IPPROTO_TCP
	290	\|\| (e->ip.invflags & IPT_INV_PROTO)) {
	291	DEBUGP("REJECT: TCP_RESET invalid for non-tcp\n");
	292	return 0;
	293	}
	294	}
1da177e4 LT	295	return 1;
	296	}
	297
	298	static struct ipt_target ipt_reject_reg = {
	299	.name = "REJECT",
	300	.target = reject,
1d5cd909 PM	301	.targetsize = sizeof(struct ipt_reject_info),
	302	.table = "filter",
	303	.hooks = (1 << NF_IP_LOCAL_IN) \| (1 << NF_IP_FORWARD) \|
	304	(1 << NF_IP_LOCAL_OUT),
1da177e4 LT	305	.checkentry = check,
	306	.me = THIS_MODULE,
	307	};
	308
65b4b4e8	309	static int __init ipt_reject_init(void)
1da177e4 LT	310	{
	311	return ipt_register_target(&ipt_reject_reg);
	312	}
	313
65b4b4e8	314	static void __exit ipt_reject_fini(void)
1da177e4 LT	315	{
	316	ipt_unregister_target(&ipt_reject_reg);
	317	}
	318
65b4b4e8 AM	319	module_init(ipt_reject_init);
65b4b4e8 AM	320	module_exit(ipt_reject_fini);