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Commit 764d8a9f authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller
Browse files

[NETFILTER]: Add IPv6 REJECT target 



Originally written by Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>,
taken from netfilter patch-o-matic and fixed up to work with current
kernels.

Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7567662b

include/linux/netfilter_ipv6/ip6t_REJECT.h

0 → 100644
+18 −0
Original line number Diff line number Diff line 
#ifndef _IP6T_REJECT_H

#define _IP6T_REJECT_H



enum ip6t_reject_with {

	IP6T_ICMP6_NO_ROUTE,

	IP6T_ICMP6_ADM_PROHIBITED,

	IP6T_ICMP6_NOT_NEIGHBOUR,

	IP6T_ICMP6_ADDR_UNREACH,

	IP6T_ICMP6_PORT_UNREACH,

	IP6T_ICMP6_ECHOREPLY,

	IP6T_TCP_RESET

};



struct ip6t_reject_info {

	u_int32_t	with;	/* reject type */

};



#endif /*_IP6T_REJECT_H*/

net/ipv6/netfilter/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -199,6 +199,16 @@ config IP6_NF_TARGET_LOG 


	  To compile it as a module, choose M here.  If unsure, say N.



config IP6_NF_TARGET_REJECT

	tristate "REJECT target support"

	depends on IP6_NF_FILTER

	help

	  The REJECT target allows a filtering rule to specify that an ICMPv6

	  error should be issued in response to an incoming packet, rather

	  than silently being dropped.



	  To compile it as a module, choose M here.  If unsure, say N.



#  if [ "$CONFIG_IP6_NF_FILTER" != "n" ]; then

#    dep_tristate '    REJECT target support' CONFIG_IP6_NF_TARGET_REJECT $CONFIG_IP6_NF_FILTER

#    if [ "$CONFIG_EXPERIMENTAL" = "y" ]; then

net/ipv6/netfilter/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -24,4 +24,5 @@ obj-$(CONFIG_IP6_NF_QUEUE) += ip6_queue.o 
obj-$(CONFIG_IP6_NF_TARGET_LOG) += ip6t_LOG.o

obj-$(CONFIG_IP6_NF_RAW) += ip6table_raw.o

obj-$(CONFIG_IP6_NF_MATCH_HL) += ip6t_hl.o

obj-$(CONFIG_IP6_NF_TARGET_REJECT) += ip6t_REJECT.o

obj-$(CONFIG_NETFILTER_NETLINK_QUEUE) += ip6t_NFQUEUE.o

net/ipv6/netfilter/ip6t_REJECT.c

0 → 100644
+284 −0
Original line number Diff line number Diff line 
/*

 * 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/config.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_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;

	dst = ip6_route_output(NULL, &fl);

	if (dst == NULL)

		return;

	if (dst->error ||

	    xfrm_lookup(&dst, &fl, NULL, 0)) {

		dst_release(dst);

		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_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 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 struct ip6t_entry *e,

		 void *targinfo,

		 unsigned int targinfosize,

		 unsigned int hook_mask)

{

 	const struct ip6t_reject_info *rejinfo = targinfo;



 	if (targinfosize != IP6T_ALIGN(sizeof(struct ip6t_reject_info))) {

  		DEBUGP("ip6t_REJECT: targinfosize %u != 0\n", targinfosize);

  		return 0;

  	}



	/* Only allow these for packet filtering. */

	if (strcmp(tablename, "filter") != 0) {

		DEBUGP("ip6t_REJECT: bad table `%s'.\n", tablename);

		return 0;

	}



	if ((hook_mask & ~((1 << NF_IP6_LOCAL_IN)

			   | (1 << NF_IP6_FORWARD)

			   | (1 << NF_IP6_LOCAL_OUT))) != 0) {

		DEBUGP("ip6t_REJECT: bad hook mask %X\n", hook_mask);

		return 0;

	}



	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,

	.checkentry	= check,

	.me		= THIS_MODULE

};



static int __init init(void)

{

	if (ip6t_register_target(&ip6t_reject_reg))

		return -EINVAL;

	return 0;

}



static void __exit fini(void)

{

	ip6t_unregister_target(&ip6t_reject_reg);

}



module_init(init);

module_exit(fini);