net/ipv4/netfilter/nf_conntrack_proto_icmp.c - linux/kernel/git/bpf/bpf-next - Git at Google

 /* (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.
  *
  * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
  *	- enable working with Layer 3 protocol independent connection tracking.
  *
  * Derived from net/ipv4/netfilter/ip_conntrack_proto_icmp.c
  */

 #include <linux/types.h>
 #include <linux/sched.h>
 #include <linux/timer.h>
 #include <linux/netfilter.h>
 #include <linux/in.h>
 #include <linux/icmp.h>
 #include <linux/seq_file.h>
 #include <net/ip.h>
 #include <net/checksum.h>
 #include <linux/netfilter_ipv4.h>
 #include <net/netfilter/nf_conntrack_tuple.h>
 #include <net/netfilter/nf_conntrack_protocol.h>
 #include <net/netfilter/nf_conntrack_core.h>

 unsigned long nf_ct_icmp_timeout = 30*HZ;

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

 static int icmp_pkt_to_tuple(const struct sk_buff *skb,
 			     unsigned int dataoff,
 			     struct nf_conntrack_tuple *tuple)
 {
 	struct icmphdr _hdr, *hp;

 	hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 	if (hp == NULL)
 		return 0;

 	tuple->dst.u.icmp.type = hp->type;
 	tuple->src.u.icmp.id = hp->un.echo.id;
 	tuple->dst.u.icmp.code = hp->code;

 	return 1;
 }

 /* Add 1; spaces filled with 0. */
 static const u_int8_t invmap[] = {
 	[ICMP_ECHO] = ICMP_ECHOREPLY + 1,
 	[ICMP_ECHOREPLY] = ICMP_ECHO + 1,
 	[ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
 	[ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
 	[ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
 	[ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
 	[ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
 	[ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
 };

 static int icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
 			     const struct nf_conntrack_tuple *orig)
 {
 	if (orig->dst.u.icmp.type >= sizeof(invmap)
 	    || !invmap[orig->dst.u.icmp.type])
 		return 0;

 	tuple->src.u.icmp.id = orig->src.u.icmp.id;
 	tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
 	tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
 	return 1;
 }

 /* Print out the per-protocol part of the tuple. */
 static int icmp_print_tuple(struct seq_file *s,
 			    const struct nf_conntrack_tuple *tuple)
 {
 	return seq_printf(s, "type=%u code=%u id=%u ",
 			  tuple->dst.u.icmp.type,
 			  tuple->dst.u.icmp.code,
 			  ntohs(tuple->src.u.icmp.id));
 }

 /* Print out the private part of the conntrack. */
 static int icmp_print_conntrack(struct seq_file *s,
 				const struct nf_conn *conntrack)
 {
 	return 0;
 }

 /* Returns verdict for packet, or -1 for invalid. */
 static int icmp_packet(struct nf_conn *ct,
 		       const struct sk_buff *skb,
 		       unsigned int dataoff,
 		       enum ip_conntrack_info ctinfo,
 		       int pf,
 		       unsigned int hooknum)
 {
 	/* Try to delete connection immediately after all replies:
            won't actually vanish as we still have skb, and del_timer
            means this will only run once even if count hits zero twice
            (theoretically possible with SMP) */
 	if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
 		if (atomic_dec_and_test(&ct->proto.icmp.count)
 		    && del_timer(&ct->timeout))
 			ct->timeout.function((unsigned long)ct);
 	} else {
 		atomic_inc(&ct->proto.icmp.count);
 		nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
 		nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
 	}

 	return NF_ACCEPT;
 }

 /* Called when a new connection for this protocol found. */
 static int icmp_new(struct nf_conn *conntrack,
 		    const struct sk_buff *skb, unsigned int dataoff)
 {
 	static const u_int8_t valid_new[] = {
 		[ICMP_ECHO] = 1,
 		[ICMP_TIMESTAMP] = 1,
 		[ICMP_INFO_REQUEST] = 1,
 		[ICMP_ADDRESS] = 1
 	};

 	if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
 	    || !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) {
 		/* Can't create a new ICMP `conn' with this. */
 		DEBUGP("icmp: can't create new conn with type %u\n",
 		       conntrack->tuplehash[0].tuple.dst.u.icmp.type);
 		NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
 		return 0;
 	}
 	atomic_set(&conntrack->proto.icmp.count, 0);
 	return 1;
 }

 extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4;
 /* Returns conntrack if it dealt with ICMP, and filled in skb fields */
 static int
 icmp_error_message(struct sk_buff *skb,
                  enum ip_conntrack_info *ctinfo,
                  unsigned int hooknum)
 {
 	struct nf_conntrack_tuple innertuple, origtuple;
 	struct {
 		struct icmphdr icmp;
 		struct iphdr ip;
 	} _in, *inside;
 	struct nf_conntrack_protocol *innerproto;
 	struct nf_conntrack_tuple_hash *h;
 	int dataoff;

 	NF_CT_ASSERT(skb->nfct == NULL);

 	/* Not enough header? */
 	inside = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_in), &_in);
 	if (inside == NULL)
 		return -NF_ACCEPT;

 	/* Ignore ICMP's containing fragments (shouldn't happen) */
 	if (inside->ip.frag_off & htons(IP_OFFSET)) {
 		DEBUGP("icmp_error_message: fragment of proto %u\n",
 		       inside->ip.protocol);
 		return -NF_ACCEPT;
 	}

 	innerproto = __nf_ct_proto_find(PF_INET, inside->ip.protocol);
 	dataoff = skb->nh.iph->ihl*4 + sizeof(inside->icmp);
 	/* Are they talking about one of our connections? */
 	if (!nf_ct_get_tuple(skb, dataoff, dataoff + inside->ip.ihl*4, PF_INET,
 			     inside->ip.protocol, &origtuple,
 			     &nf_conntrack_l3proto_ipv4, innerproto)) {
 		DEBUGP("icmp_error_message: ! get_tuple p=%u",
 		       inside->ip.protocol);
 		return -NF_ACCEPT;
 	}

         /* Ordinarily, we'd expect the inverted tupleproto, but it's
            been preserved inside the ICMP. */
         if (!nf_ct_invert_tuple(&innertuple, &origtuple,
 				&nf_conntrack_l3proto_ipv4, innerproto)) {
 		DEBUGP("icmp_error_message: no match\n");
 		return -NF_ACCEPT;
 	}

 	*ctinfo = IP_CT_RELATED;

 	h = nf_conntrack_find_get(&innertuple, NULL);
 	if (!h) {
 		/* Locally generated ICMPs will match inverted if they
 		   haven't been SNAT'ed yet */
 		/* FIXME: NAT code has to handle half-done double NAT --RR */
 		if (hooknum == NF_IP_LOCAL_OUT)
 			h = nf_conntrack_find_get(&origtuple, NULL);

 		if (!h) {
 			DEBUGP("icmp_error_message: no match\n");
 			return -NF_ACCEPT;
 		}

 		/* Reverse direction from that found */
 		if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 			*ctinfo += IP_CT_IS_REPLY;
 	} else {
 		if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 			*ctinfo += IP_CT_IS_REPLY;
 	}

         /* Update skb to refer to this connection */
         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
         skb->nfctinfo = *ctinfo;
         return -NF_ACCEPT;
 }

 /* Small and modified version of icmp_rcv */
 static int
 icmp_error(struct sk_buff *skb, unsigned int dataoff,
 	   enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
 {
 	struct icmphdr _ih, *icmph;

 	/* Not enough header? */
 	icmph = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_ih), &_ih);
 	if (icmph == NULL) {
 		if (LOG_INVALID(IPPROTO_ICMP))
 			nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
 				      "nf_ct_icmp: short packet ");
 		return -NF_ACCEPT;
 	}

 	/* See ip_conntrack_proto_tcp.c */
 	if (hooknum != NF_IP_PRE_ROUTING)
 		goto checksum_skipped;

 	switch (skb->ip_summed) {
 	case CHECKSUM_HW:
 		if (!(u16)csum_fold(skb->csum))
 			break;
 		if (LOG_INVALID(IPPROTO_ICMP))
 			nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
 				      "nf_ct_icmp: bad HW ICMP checksum ");
 		return -NF_ACCEPT;
 	case CHECKSUM_NONE:
 		if ((u16)csum_fold(skb_checksum(skb, 0, skb->len, 0))) {
 			if (LOG_INVALID(IPPROTO_ICMP))
 				nf_log_packet(PF_INET, 0, skb, NULL, NULL,
 					      NULL,
 					      "nf_ct_icmp: bad ICMP checksum ");
 			return -NF_ACCEPT;
 		}
 	default:
 		break;
 	}

 checksum_skipped:
 	/*
 	 *	18 is the highest 'known' ICMP type. Anything else is a mystery
 	 *
 	 *	RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
 	 *		  discarded.
 	 */
 	if (icmph->type > NR_ICMP_TYPES) {
 		if (LOG_INVALID(IPPROTO_ICMP))
 			nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
 				      "nf_ct_icmp: invalid ICMP type ");
 		return -NF_ACCEPT;
 	}

 	/* Need to track icmp error message? */
 	if (icmph->type != ICMP_DEST_UNREACH
 	    && icmph->type != ICMP_SOURCE_QUENCH
 	    && icmph->type != ICMP_TIME_EXCEEDED
 	    && icmph->type != ICMP_PARAMETERPROB
 	    && icmph->type != ICMP_REDIRECT)
 		return NF_ACCEPT;

 	return icmp_error_message(skb, ctinfo, hooknum);
 }

 #if defined(CONFIG_NF_CT_NETLINK) || \
     defined(CONFIG_NF_CT_NETLINK_MODULE)

 #include <linux/netfilter/nfnetlink.h>
 #include <linux/netfilter/nfnetlink_conntrack.h>

 static int icmp_tuple_to_nfattr(struct sk_buff *skb,
 				const struct nf_conntrack_tuple *t)
 {
 	NFA_PUT(skb, CTA_PROTO_ICMP_ID, sizeof(u_int16_t),
 		&t->src.u.icmp.id);
 	NFA_PUT(skb, CTA_PROTO_ICMP_TYPE, sizeof(u_int8_t),
 		&t->dst.u.icmp.type);
 	NFA_PUT(skb, CTA_PROTO_ICMP_CODE, sizeof(u_int8_t),
 		&t->dst.u.icmp.code);

 	return 0;

 nfattr_failure:
 	return -1;
 }

 static const size_t cta_min_proto[CTA_PROTO_MAX] = {
 	[CTA_PROTO_ICMP_TYPE-1] = sizeof(u_int8_t),
 	[CTA_PROTO_ICMP_CODE-1] = sizeof(u_int8_t),
 	[CTA_PROTO_ICMP_ID-1]   = sizeof(u_int16_t)
 };

 static int icmp_nfattr_to_tuple(struct nfattr *tb[],
 				struct nf_conntrack_tuple *tuple)
 {
 	if (!tb[CTA_PROTO_ICMP_TYPE-1]
 	    || !tb[CTA_PROTO_ICMP_CODE-1]
 	    || !tb[CTA_PROTO_ICMP_ID-1])
 		return -EINVAL;

 	if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
 		return -EINVAL;

 	tuple->dst.u.icmp.type =
 			*(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_TYPE-1]);
 	tuple->dst.u.icmp.code =
 			*(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_CODE-1]);
 	tuple->src.u.icmp.id =
 			*(u_int16_t *)NFA_DATA(tb[CTA_PROTO_ICMP_ID-1]);

 	if (tuple->dst.u.icmp.type >= sizeof(invmap)
 	    || !invmap[tuple->dst.u.icmp.type])
 		return -EINVAL;

 	return 0;
 }
 #endif

 struct nf_conntrack_protocol nf_conntrack_protocol_icmp =
 {
 	.list			= { NULL, NULL },
 	.l3proto		= PF_INET,
 	.proto			= IPPROTO_ICMP,
 	.name			= "icmp",
 	.pkt_to_tuple		= icmp_pkt_to_tuple,
 	.invert_tuple		= icmp_invert_tuple,
 	.print_tuple		= icmp_print_tuple,
 	.print_conntrack	= icmp_print_conntrack,
 	.packet			= icmp_packet,
 	.new			= icmp_new,
 	.error			= icmp_error,
 	.destroy		= NULL,
 	.me			= NULL,
 #if defined(CONFIG_NF_CT_NETLINK) || \
     defined(CONFIG_NF_CT_NETLINK_MODULE)
 	.tuple_to_nfattr	= icmp_tuple_to_nfattr,
 	.nfattr_to_tuple	= icmp_nfattr_to_tuple,
 #endif
 };

 EXPORT_SYMBOL(nf_conntrack_protocol_icmp);
	/* (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.
	*
	* 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
	* - enable working with Layer 3 protocol independent connection tracking.
	*
	* Derived from net/ipv4/netfilter/ip_conntrack_proto_icmp.c
	*/

	#include <linux/types.h>
	#include <linux/sched.h>
	#include <linux/timer.h>
	#include <linux/netfilter.h>
	#include <linux/in.h>
	#include <linux/icmp.h>
	#include <linux/seq_file.h>
	#include <net/ip.h>
	#include <net/checksum.h>
	#include <linux/netfilter_ipv4.h>
	#include <net/netfilter/nf_conntrack_tuple.h>
	#include <net/netfilter/nf_conntrack_protocol.h>
	#include <net/netfilter/nf_conntrack_core.h>

	unsigned long nf_ct_icmp_timeout = 30*HZ;

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

	static int icmp_pkt_to_tuple(const struct sk_buff *skb,
	unsigned int dataoff,
	struct nf_conntrack_tuple *tuple)
	{
	struct icmphdr _hdr, *hp;

	hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
	if (hp == NULL)
	return 0;

	tuple->dst.u.icmp.type = hp->type;
	tuple->src.u.icmp.id = hp->un.echo.id;
	tuple->dst.u.icmp.code = hp->code;

	return 1;
	}

	/* Add 1; spaces filled with 0. */
	static const u_int8_t invmap[] = {
	[ICMP_ECHO] = ICMP_ECHOREPLY + 1,
	[ICMP_ECHOREPLY] = ICMP_ECHO + 1,
	[ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
	[ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
	[ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
	[ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
	[ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
	[ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
	};

	static int icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
	const struct nf_conntrack_tuple *orig)
	{
	if (orig->dst.u.icmp.type >= sizeof(invmap)
	\|\| !invmap[orig->dst.u.icmp.type])
	return 0;

	tuple->src.u.icmp.id = orig->src.u.icmp.id;
	tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
	tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
	return 1;
	}

	/* Print out the per-protocol part of the tuple. */
	static int icmp_print_tuple(struct seq_file *s,
	const struct nf_conntrack_tuple *tuple)
	{
	return seq_printf(s, "type=%u code=%u id=%u ",
	tuple->dst.u.icmp.type,
	tuple->dst.u.icmp.code,
	ntohs(tuple->src.u.icmp.id));
	}

	/* Print out the private part of the conntrack. */
	static int icmp_print_conntrack(struct seq_file *s,
	const struct nf_conn *conntrack)
	{
	return 0;
	}

	/* Returns verdict for packet, or -1 for invalid. */
	static int icmp_packet(struct nf_conn *ct,
	const struct sk_buff *skb,
	unsigned int dataoff,
	enum ip_conntrack_info ctinfo,
	int pf,
	unsigned int hooknum)
	{
	/* Try to delete connection immediately after all replies:
	won't actually vanish as we still have skb, and del_timer
	means this will only run once even if count hits zero twice
	(theoretically possible with SMP) */
	if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
	if (atomic_dec_and_test(&ct->proto.icmp.count)
	&& del_timer(&ct->timeout))
	ct->timeout.function((unsigned long)ct);
	} else {
	atomic_inc(&ct->proto.icmp.count);
	nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
	nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
	}

	return NF_ACCEPT;
	}

	/* Called when a new connection for this protocol found. */
	static int icmp_new(struct nf_conn *conntrack,
	const struct sk_buff *skb, unsigned int dataoff)
	{
	static const u_int8_t valid_new[] = {
	[ICMP_ECHO] = 1,
	[ICMP_TIMESTAMP] = 1,
	[ICMP_INFO_REQUEST] = 1,
	[ICMP_ADDRESS] = 1
	};

	if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
	\|\| !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) {
	/* Can't create a new ICMP `conn' with this. */
	DEBUGP("icmp: can't create new conn with type %u\n",
	conntrack->tuplehash[0].tuple.dst.u.icmp.type);
	NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
	return 0;
	}
	atomic_set(&conntrack->proto.icmp.count, 0);
	return 1;
	}

	extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4;
	/* Returns conntrack if it dealt with ICMP, and filled in skb fields */
	static int
	icmp_error_message(struct sk_buff *skb,
	enum ip_conntrack_info *ctinfo,
	unsigned int hooknum)
	{
	struct nf_conntrack_tuple innertuple, origtuple;
	struct {
	struct icmphdr icmp;
	struct iphdr ip;
	} _in, *inside;
	struct nf_conntrack_protocol *innerproto;
	struct nf_conntrack_tuple_hash *h;
	int dataoff;

	NF_CT_ASSERT(skb->nfct == NULL);

	/* Not enough header? */
	inside = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_in), &_in);
	if (inside == NULL)
	return -NF_ACCEPT;

	/* Ignore ICMP's containing fragments (shouldn't happen) */
	if (inside->ip.frag_off & htons(IP_OFFSET)) {
	DEBUGP("icmp_error_message: fragment of proto %u\n",
	inside->ip.protocol);
	return -NF_ACCEPT;
	}

	innerproto = __nf_ct_proto_find(PF_INET, inside->ip.protocol);
	dataoff = skb->nh.iph->ihl*4 + sizeof(inside->icmp);
	/* Are they talking about one of our connections? */
	if (!nf_ct_get_tuple(skb, dataoff, dataoff + inside->ip.ihl*4, PF_INET,
	inside->ip.protocol, &origtuple,
	&nf_conntrack_l3proto_ipv4, innerproto)) {
	DEBUGP("icmp_error_message: ! get_tuple p=%u",
	inside->ip.protocol);
	return -NF_ACCEPT;
	}

	/* Ordinarily, we'd expect the inverted tupleproto, but it's
	been preserved inside the ICMP. */
	if (!nf_ct_invert_tuple(&innertuple, &origtuple,
	&nf_conntrack_l3proto_ipv4, innerproto)) {
	DEBUGP("icmp_error_message: no match\n");
	return -NF_ACCEPT;
	}

	*ctinfo = IP_CT_RELATED;

	h = nf_conntrack_find_get(&innertuple, NULL);
	if (!h) {
	/* Locally generated ICMPs will match inverted if they
	haven't been SNAT'ed yet */
	/* FIXME: NAT code has to handle half-done double NAT --RR */
	if (hooknum == NF_IP_LOCAL_OUT)
	h = nf_conntrack_find_get(&origtuple, NULL);

	if (!h) {
	DEBUGP("icmp_error_message: no match\n");
	return -NF_ACCEPT;
	}

	/* Reverse direction from that found */
	if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
	*ctinfo += IP_CT_IS_REPLY;
	} else {
	if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
	*ctinfo += IP_CT_IS_REPLY;
	}

	/* Update skb to refer to this connection */
	skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
	skb->nfctinfo = *ctinfo;
	return -NF_ACCEPT;
	}

	/* Small and modified version of icmp_rcv */
	static int
	icmp_error(struct sk_buff *skb, unsigned int dataoff,
	enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
	{
	struct icmphdr _ih, *icmph;

	/* Not enough header? */
	icmph = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_ih), &_ih);
	if (icmph == NULL) {
	if (LOG_INVALID(IPPROTO_ICMP))
	nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
	"nf_ct_icmp: short packet ");
	return -NF_ACCEPT;
	}

	/* See ip_conntrack_proto_tcp.c */
	if (hooknum != NF_IP_PRE_ROUTING)
	goto checksum_skipped;

	switch (skb->ip_summed) {
	case CHECKSUM_HW:
	if (!(u16)csum_fold(skb->csum))
	break;
	if (LOG_INVALID(IPPROTO_ICMP))
	nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
	"nf_ct_icmp: bad HW ICMP checksum ");
	return -NF_ACCEPT;
	case CHECKSUM_NONE:
	if ((u16)csum_fold(skb_checksum(skb, 0, skb->len, 0))) {
	if (LOG_INVALID(IPPROTO_ICMP))
	nf_log_packet(PF_INET, 0, skb, NULL, NULL,
	NULL,
	"nf_ct_icmp: bad ICMP checksum ");
	return -NF_ACCEPT;
	}
	default:
	break;
	}

	checksum_skipped:
	/*
	* 18 is the highest 'known' ICMP type. Anything else is a mystery
	*
	* RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
	* discarded.
	*/
	if (icmph->type > NR_ICMP_TYPES) {
	if (LOG_INVALID(IPPROTO_ICMP))
	nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
	"nf_ct_icmp: invalid ICMP type ");
	return -NF_ACCEPT;
	}

	/* Need to track icmp error message? */
	if (icmph->type != ICMP_DEST_UNREACH
	&& icmph->type != ICMP_SOURCE_QUENCH
	&& icmph->type != ICMP_TIME_EXCEEDED
	&& icmph->type != ICMP_PARAMETERPROB
	&& icmph->type != ICMP_REDIRECT)
	return NF_ACCEPT;

	return icmp_error_message(skb, ctinfo, hooknum);
	}

	#if defined(CONFIG_NF_CT_NETLINK) \|\| \
	defined(CONFIG_NF_CT_NETLINK_MODULE)

	#include <linux/netfilter/nfnetlink.h>
	#include <linux/netfilter/nfnetlink_conntrack.h>

	static int icmp_tuple_to_nfattr(struct sk_buff *skb,
	const struct nf_conntrack_tuple *t)
	{
	NFA_PUT(skb, CTA_PROTO_ICMP_ID, sizeof(u_int16_t),
	&t->src.u.icmp.id);
	NFA_PUT(skb, CTA_PROTO_ICMP_TYPE, sizeof(u_int8_t),
	&t->dst.u.icmp.type);
	NFA_PUT(skb, CTA_PROTO_ICMP_CODE, sizeof(u_int8_t),
	&t->dst.u.icmp.code);

	return 0;

	nfattr_failure:
	return -1;
	}

	static const size_t cta_min_proto[CTA_PROTO_MAX] = {
	[CTA_PROTO_ICMP_TYPE-1] = sizeof(u_int8_t),
	[CTA_PROTO_ICMP_CODE-1] = sizeof(u_int8_t),
	[CTA_PROTO_ICMP_ID-1] = sizeof(u_int16_t)
	};

	static int icmp_nfattr_to_tuple(struct nfattr *tb[],
	struct nf_conntrack_tuple *tuple)
	{
	if (!tb[CTA_PROTO_ICMP_TYPE-1]
	\|\| !tb[CTA_PROTO_ICMP_CODE-1]
	\|\| !tb[CTA_PROTO_ICMP_ID-1])
	return -EINVAL;

	if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
	return -EINVAL;

	tuple->dst.u.icmp.type =
	(u_int8_t )NFA_DATA(tb[CTA_PROTO_ICMP_TYPE-1]);
	tuple->dst.u.icmp.code =
	(u_int8_t )NFA_DATA(tb[CTA_PROTO_ICMP_CODE-1]);
	tuple->src.u.icmp.id =
	(u_int16_t )NFA_DATA(tb[CTA_PROTO_ICMP_ID-1]);

	if (tuple->dst.u.icmp.type >= sizeof(invmap)
	\|\| !invmap[tuple->dst.u.icmp.type])
	return -EINVAL;

	return 0;
	}
	#endif

	struct nf_conntrack_protocol nf_conntrack_protocol_icmp =
	{
	.list = { NULL, NULL },
	.l3proto = PF_INET,
	.proto = IPPROTO_ICMP,
	.name = "icmp",
	.pkt_to_tuple = icmp_pkt_to_tuple,
	.invert_tuple = icmp_invert_tuple,
	.print_tuple = icmp_print_tuple,
	.print_conntrack = icmp_print_conntrack,
	.packet = icmp_packet,
	.new = icmp_new,
	.error = icmp_error,
	.destroy = NULL,
	.me = NULL,
	#if defined(CONFIG_NF_CT_NETLINK) \|\| \
	defined(CONFIG_NF_CT_NETLINK_MODULE)
	.tuple_to_nfattr = icmp_tuple_to_nfattr,
	.nfattr_to_tuple = icmp_nfattr_to_tuple,
	#endif
	};

	EXPORT_SYMBOL(nf_conntrack_protocol_icmp);