[NETFILTER]: New ip_conntrack_sctp

Incremental to all other patches so far, there is also the new SCTP
conntrack helper by Kiran Kumar.  Please apply for 2.6.9 ++, thanks.
Signed-off-by: Kiran Kumar Immidi <immidi_kiran@yahoo.com>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@redhat.com>

include/linux/netfilter_ipv4/ip_conntrack.h

@@ -51,10 +51,12 @@ enum ip_conntrack_status {
 
 #include <linux/netfilter_ipv4/ip_conntrack_tcp.h>
 #include <linux/netfilter_ipv4/ip_conntrack_icmp.h>
+#include <linux/netfilter_ipv4/ip_conntrack_sctp.h>
 
 /* per conntrack: protocol private data */
 union ip_conntrack_proto {
 	/* insert conntrack proto private data here */
+	struct ip_ct_sctp sctp;
 	struct ip_ct_tcp tcp;
 	struct ip_ct_icmp icmp;
 };

include/linux/netfilter_ipv4/ip_conntrack_sctp.h

+#ifndef _IP_CONNTRACK_SCTP_H
+#define _IP_CONNTRACK_SCTP_H
+/* SCTP tracking. */
+
+enum sctp_conntrack {
+	SCTP_CONNTRACK_NONE,
+	SCTP_CONNTRACK_CLOSED,
+	SCTP_CONNTRACK_COOKIE_WAIT,
+	SCTP_CONNTRACK_COOKIE_ECHOED,
+	SCTP_CONNTRACK_ESTABLISHED,
+	SCTP_CONNTRACK_SHUTDOWN_SENT,
+	SCTP_CONNTRACK_SHUTDOWN_RECD,
+	SCTP_CONNTRACK_SHUTDOWN_ACK_SENT,
+	SCTP_CONNTRACK_MAX
+};
+
+struct ip_ct_sctp
+{
+	enum sctp_conntrack state;
+
+	u_int32_t vtag[IP_CT_DIR_MAX];
+	u_int32_t ttag[IP_CT_DIR_MAX];
+};
+
+#endif /* _IP_CONNTRACK_SCTP_H */

include/linux/netfilter_ipv4/ip_conntrack_tuple.h

@@ -25,6 +25,9 @@ union ip_conntrack_manip_proto
 	struct {
 		u_int16_t id;
 	} icmp;
+	struct {
+		u_int16_t port;
+	} sctp;
 };
 
 /* The manipulable part of the tuple. */
@@ -55,6 +58,9 @@ struct ip_conntrack_tuple
 			struct {
 				u_int8_t type, code;
 			} icmp;
+			struct {
+				u_int16_t port;
+			} sctp;
 		} u;
 
 		/* The protocol. */

include/linux/sysctl.h

@@ -415,6 +415,13 @@ enum
 	NET_IPV4_NF_CONNTRACK_TCP_LOOSE=17,
 	NET_IPV4_NF_CONNTRACK_TCP_BE_LIBERAL=18,
 	NET_IPV4_NF_CONNTRACK_TCP_MAX_RETRANS=19,
+ 	NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_CLOSED=20,
+ 	NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_COOKIE_WAIT=21,
+ 	NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_COOKIE_ECHOED=22,
+ 	NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_ESTABLISHED=23,
+ 	NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_SHUTDOWN_SENT=24,
+ 	NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_SHUTDOWN_RECD=25,
+ 	NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_SHUTDOWN_ACK_SENT=26,
 };
  
 /* /proc/sys/net/ipv6 */

net/ipv4/netfilter/Kconfig

@@ -636,5 +636,9 @@ config IP_NF_MATCH_SCTP
 	tristate  'SCTP protocol match support'
 	depends on IP_NF_IPTABLES
 
+config IP_NF_CT_PROTO_SCTP
+	tristate  'SCTP protocol connection tracking support (EXPERIMENTAL)'
+	depends on IP_NF_CONNTRACK && EXPERIMENTAL
+
 endmenu
 

net/ipv4/netfilter/Makefile

@@ -19,6 +19,9 @@ ipchains-objs		:= $(ip_nf_compat-objs) ipchains_core.o
 # connection tracking
 obj-$(CONFIG_IP_NF_CONNTRACK) += ip_conntrack.o
 
+# SCTP protocol connection tracking
+obj-$(CONFIG_IP_NF_CT_PROTO_SCTP) += ip_conntrack_proto_sctp.o
+
 # connection tracking helpers
 obj-$(CONFIG_IP_NF_AMANDA) += ip_conntrack_amanda.o
 obj-$(CONFIG_IP_NF_TFTP) += ip_conntrack_tftp.o

net/ipv4/netfilter/ip_conntrack_proto_sctp.c

+/*
+ * Connection tracking protocol helper module for SCTP.
+ * 
+ * SCTP is defined in RFC 2960. References to various sections in this code 
+ * are to this RFC.
+ * 
+ * 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.
+ */
+
+/*
+ * Added support for proc manipulation of timeouts.
+ */
+
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
+#include <linux/netfilter.h>
+#include <linux/module.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/sctp.h>
+#include <linux/string.h>
+
+#include <linux/netfilter_ipv4/ip_conntrack.h>
+#include <linux/netfilter_ipv4/ip_conntrack_protocol.h>
+#include <linux/netfilter_ipv4/lockhelp.h>
+
+#if 0
+#define DEBUGP(format, ...) printk(format, ## __VA_ARGS__)
+#else
+#define DEBUGP(format, args...)
+#endif
+
+/* Protects conntrack->proto.sctp */
+static DECLARE_RWLOCK(sctp_lock);
+
+/* FIXME: Examine ipfilter's timeouts and conntrack transitions more
+   closely.  They're more complex. --RR 
+
+   And so for me for SCTP :D -Kiran */
+
+static const char *sctp_conntrack_names[] = {
+	"NONE",
+	"CLOSED",
+	"COOKIE_WAIT",
+	"COOKIE_ECHOED",
+	"ESTABLISHED",
+	"SHUTDOWN_SENT",
+	"SHUTDOWN_RECD",
+	"SHUTDOWN_ACK_SENT",
+};
+
+#define SECS  * HZ
+#define MINS  * 60 SECS
+#define HOURS * 60 MINS
+#define DAYS  * 24 HOURS
+
+unsigned long ip_ct_sctp_timeout_closed            =  10 SECS;
+unsigned long ip_ct_sctp_timeout_cookie_wait       =   3 SECS;
+unsigned long ip_ct_sctp_timeout_cookie_echoed     =   3 SECS;
+unsigned long ip_ct_sctp_timeout_established       =   5 DAYS;
+unsigned long ip_ct_sctp_timeout_shutdown_sent     = 300 SECS / 1000;
+unsigned long ip_ct_sctp_timeout_shutdown_recd     = 300 SECS / 1000;
+unsigned long ip_ct_sctp_timeout_shutdown_ack_sent =   3 SECS;
+
+static unsigned long * sctp_timeouts[]
+= { 0,                                     /* SCTP_CONNTRACK_NONE  */
+    &ip_ct_sctp_timeout_closed,	           /* SCTP_CONNTRACK_CLOSED */
+    &ip_ct_sctp_timeout_cookie_wait,       /* SCTP_CONNTRACK_COOKIE_WAIT */
+    &ip_ct_sctp_timeout_cookie_echoed,     /* SCTP_CONNTRACK_COOKIE_ECHOED */
+    &ip_ct_sctp_timeout_established,       /* SCTP_CONNTRACK_ESTABLISHED */
+    &ip_ct_sctp_timeout_shutdown_sent,     /* SCTP_CONNTRACK_SHUTDOWN_SENT */
+    &ip_ct_sctp_timeout_shutdown_recd,     /* SCTP_CONNTRACK_SHUTDOWN_RECD */
+    &ip_ct_sctp_timeout_shutdown_ack_sent  /* SCTP_CONNTRACK_SHUTDOWN_ACK_SENT */
+ };
+
+#define sNO SCTP_CONNTRACK_NONE
+#define	sCL SCTP_CONNTRACK_CLOSED
+#define	sCW SCTP_CONNTRACK_COOKIE_WAIT
+#define	sCE SCTP_CONNTRACK_COOKIE_ECHOED
+#define	sES SCTP_CONNTRACK_ESTABLISHED
+#define	sSS SCTP_CONNTRACK_SHUTDOWN_SENT
+#define	sSR SCTP_CONNTRACK_SHUTDOWN_RECD
+#define	sSA SCTP_CONNTRACK_SHUTDOWN_ACK_SENT
+#define	sIV SCTP_CONNTRACK_MAX
+
+/* 
+	These are the descriptions of the states:
+
+NOTE: These state names are tantalizingly similar to the states of an 
+SCTP endpoint. But the interpretation of the states is a little different,
+considering that these are the states of the connection and not of an end 
+point. Please note the subtleties. -Kiran
+
+NONE              - Nothing so far.
+COOKIE WAIT       - We have seen an INIT chunk in the original direction, or also 
+                    an INIT_ACK chunk in the reply direction.
+COOKIE ECHOED     - We have seen a COOKIE_ECHO chunk in the original direction.
+ESTABLISHED       - We have seen a COOKIE_ACK in the reply direction.
+SHUTDOWN_SENT     - We have seen a SHUTDOWN chunk in the original direction.
+SHUTDOWN_RECD     - We have seen a SHUTDOWN chunk in the reply directoin.
+SHUTDOWN_ACK_SENT - We have seen a SHUTDOWN_ACK chunk in the direction opposite
+                    to that of the SHUTDOWN chunk.
+CLOSED            - We have seen a SHUTDOWN_COMPLETE chunk in the direction of 
+                    the SHUTDOWN chunk. Connection is closed.
+*/
+
+/* TODO
+ - I have assumed that the first INIT is in the original direction. 
+ This messes things when an INIT comes in the reply direction in CLOSED
+ state.
+ - Check the error type in the reply dir before transitioning from 
+cookie echoed to closed.
+ - Sec 5.2.4 of RFC 2960
+ - Multi Homing support.
+*/
+
+/* SCTP conntrack state transitions */
+static enum sctp_conntrack sctp_conntracks[2][9][SCTP_CONNTRACK_MAX] = {
+	{
+/*	ORIGINAL	*/
+/*                  sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA */
+/* init         */ {sCW, sCW, sCW, sCE, sES, sSS, sSR, sSA},
+/* init_ack     */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA},
+/* abort        */ {sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL},
+/* shutdown     */ {sCL, sCL, sCW, sCE, sSS, sSS, sSR, sSA},
+/* shutdown_ack */ {sSA, sCL, sCW, sCE, sES, sSA, sSA, sSA},
+/* error        */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA},/* Cant have Stale cookie*/
+/* cookie_echo  */ {sCL, sCL, sCE, sCE, sES, sSS, sSR, sSA},/* 5.2.4 - Big TODO */
+/* cookie_ack   */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA},/* Cant come in orig dir */
+/* shutdown_comp*/ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sCL}
+	},
+	{
+/*	REPLY	*/
+/*                  sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA */
+/* init         */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA},/* INIT in sCL Big TODO */
+/* init_ack     */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA},
+/* abort        */ {sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL},
+/* shutdown     */ {sIV, sCL, sCW, sCE, sSR, sSS, sSR, sSA},
+/* shutdown_ack */ {sIV, sCL, sCW, sCE, sES, sSA, sSA, sSA},
+/* error        */ {sIV, sCL, sCW, sCL, sES, sSS, sSR, sSA},
+/* cookie_echo  */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA},/* Cant come in reply dir */
+/* cookie_ack   */ {sIV, sCL, sCW, sES, sES, sSS, sSR, sSA},
+/* shutdown_comp*/ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sCL}
+	}
+};
+
+static int sctp_pkt_to_tuple(const struct sk_buff *skb,
+			     unsigned int dataoff,
+			     struct ip_conntrack_tuple *tuple)
+{
+	sctp_sctphdr_t hdr;
+
+	DEBUGP(__FUNCTION__);
+	DEBUGP("\n");
+
+	/* Actually only need first 8 bytes. */
+	if (skb_copy_bits(skb, dataoff, &hdr, 8) != 0)
+		return 0;
+
+	tuple->src.u.sctp.port = hdr.source;
+	tuple->dst.u.sctp.port = hdr.dest;
+
+	return 1;
+}
+
+static int sctp_invert_tuple(struct ip_conntrack_tuple *tuple,
+			     const struct ip_conntrack_tuple *orig)
+{
+	DEBUGP(__FUNCTION__);
+	DEBUGP("\n");
+
+	tuple->src.u.sctp.port = orig->dst.u.sctp.port;
+	tuple->dst.u.sctp.port = orig->src.u.sctp.port;
+	return 1;
+}
+
+/* Print out the per-protocol part of the tuple. */
+static unsigned int sctp_print_tuple(char *buffer,
+				     const struct ip_conntrack_tuple *tuple)
+{
+	DEBUGP(__FUNCTION__);
+	DEBUGP("\n");
+
+	return sprintf(buffer, "sport=%hu dport=%hu ",
+		       ntohs(tuple->src.u.sctp.port),
+		       ntohs(tuple->dst.u.sctp.port));
+}
+
+/* Print out the private part of the conntrack. */
+static unsigned int sctp_print_conntrack(char *buffer,
+					 const struct ip_conntrack *conntrack)
+{
+	enum sctp_conntrack state;
+
+	DEBUGP(__FUNCTION__);
+	DEBUGP("\n");
+
+	READ_LOCK(&sctp_lock);
+	state = conntrack->proto.sctp.state;
+	READ_UNLOCK(&sctp_lock);
+
+	return sprintf(buffer, "%s ", sctp_conntrack_names[state]);
+}
+
+#define for_each_sctp_chunk(skb, sch, offset, count)	\
+for (offset = skb->nh.iph->ihl * 4 + sizeof (sctp_sctphdr_t), count = 0;	\
+	offset < skb->len && !skb_copy_bits(skb, offset, &sch, sizeof(sch));	\
+	offset += (htons(sch.length) + 3) & ~3, count++)
+
+/* Some validity checks to make sure the chunks are fine */
+static int do_basic_checks(struct ip_conntrack *conntrack,
+			   const struct sk_buff *skb,
+			   char *map)
+{
+	u_int32_t offset, count;
+	sctp_chunkhdr_t sch;
+	int flag;
+
+	DEBUGP(__FUNCTION__);
+	DEBUGP("\n");
+
+	flag = 0;
+
+	for_each_sctp_chunk (skb, sch, offset, count) {
+		DEBUGP("Chunk Num: %d  Type: %d\n", count, sch.type);
+
+		if (sch.type == SCTP_CID_INIT 
+			|| sch.type == SCTP_CID_INIT_ACK
+			|| sch.type == SCTP_CID_SHUTDOWN_COMPLETE) {
+			flag = 1;
+		}
+
+		/* Cookie Ack/Echo chunks not the first OR 
+		   Init / Init Ack / Shutdown compl chunks not the only chunks */
+		if ((sch.type == SCTP_CID_COOKIE_ACK 
+			|| sch.type == SCTP_CID_COOKIE_ECHO
+			|| flag)
+		     && count !=0 ) {
+			DEBUGP("Basic checks failed\n");
+			return 1;
+		}
+
+		if (map) {
+			set_bit (sch.type, (void *)map);
+		}
+	}
+
+	DEBUGP("Basic checks passed\n");
+	return 0;
+}
+
+static int new_state(enum ip_conntrack_dir dir,
+		     enum sctp_conntrack cur_state,
+		     int chunk_type)
+{
+	int i;
+
+	DEBUGP(__FUNCTION__);
+	DEBUGP("\n");
+
+	DEBUGP("Chunk type: %d\n", chunk_type);
+
+	switch (chunk_type) {
+		case SCTP_CID_INIT: 
+			DEBUGP("SCTP_CID_INIT\n");
+			i = 0; break;
+		case SCTP_CID_INIT_ACK: 
+			DEBUGP("SCTP_CID_INIT_ACK\n");
+			i = 1; break;
+		case SCTP_CID_ABORT: 
+			DEBUGP("SCTP_CID_ABORT\n");
+			i = 2; break;
+		case SCTP_CID_SHUTDOWN: 
+			DEBUGP("SCTP_CID_SHUTDOWN\n");
+			i = 3; break;
+		case SCTP_CID_SHUTDOWN_ACK: 
+			DEBUGP("SCTP_CID_SHUTDOWN_ACK\n");
+			i = 4; break;
+		case SCTP_CID_ERROR: 
+			DEBUGP("SCTP_CID_ERROR\n");
+			i = 5; break;
+		case SCTP_CID_COOKIE_ECHO: 
+			DEBUGP("SCTP_CID_COOKIE_ECHO\n");
+			i = 6; break;
+		case SCTP_CID_COOKIE_ACK: 
+			DEBUGP("SCTP_CID_COOKIE_ACK\n");
+			i = 7; break;
+		case SCTP_CID_SHUTDOWN_COMPLETE: 
+			DEBUGP("SCTP_CID_SHUTDOWN_COMPLETE\n");
+			i = 8; break;
+		default:
+			/* Other chunks like DATA, SACK, HEARTBEAT and
+			its ACK do not cause a change in state */
+			DEBUGP("Unknown chunk type, Will stay in %s\n", 
+						sctp_conntrack_names[cur_state]);
+			return cur_state;
+	}
+
+	DEBUGP("dir: %d   cur_state: %s  chunk_type: %d  new_state: %s\n", 
+			dir, sctp_conntrack_names[cur_state], chunk_type,
+			sctp_conntrack_names[sctp_conntracks[dir][i][cur_state]]);
+
+	return sctp_conntracks[dir][i][cur_state];
+}
+
+/* Returns verdict for packet, or -1 for invalid. */
+static int sctp_packet(struct ip_conntrack *conntrack,
+		       const struct sk_buff *skb,
+		       enum ip_conntrack_info ctinfo)
+{
+	enum sctp_conntrack newconntrack, oldsctpstate;
+	sctp_sctphdr_t sctph;
+	sctp_chunkhdr_t sch;
+	u_int32_t offset, count;
+	char map[256 / sizeof (char)] = {0};
+
+	DEBUGP(__FUNCTION__);
+	DEBUGP("\n");
+
+	if (skb_copy_bits(skb, skb->nh.iph->ihl * 4, &sctph, sizeof(sctph)) != 0)
+		return -1;
+
+	if (do_basic_checks(conntrack, skb, map) != 0)
+		return -1;
+
+	/* Check the verification tag (Sec 8.5) */
+	if (!test_bit(SCTP_CID_INIT, (void *)map)
+		&& !test_bit(SCTP_CID_SHUTDOWN_COMPLETE, (void *)map)
+		&& !test_bit(SCTP_CID_COOKIE_ECHO, (void *)map)
+		&& !test_bit(SCTP_CID_ABORT, (void *)map)
+		&& !test_bit(SCTP_CID_SHUTDOWN_ACK, (void *)map)
+		&& (sctph.vtag != conntrack->proto.sctp.vtag[CTINFO2DIR(ctinfo)])) {
+		DEBUGP("Verification tag check failed\n");
+		return -1;
+	}
+
+	oldsctpstate = newconntrack = SCTP_CONNTRACK_MAX;
+	for_each_sctp_chunk (skb, sch, offset, count) {
+		WRITE_LOCK(&sctp_lock);
+
+		/* Special cases of Verification tag check (Sec 8.5.1) */
+		if (sch.type == SCTP_CID_INIT) {
+			/* Sec 8.5.1 (A) */
+			if (sctph.vtag != 0) {
+				WRITE_UNLOCK(&sctp_lock);
+				return -1;
+			}
+		} else if (sch.type == SCTP_CID_ABORT) {
+			/* Sec 8.5.1 (B) */
+			if (!(sctph.vtag == conntrack->proto.sctp.vtag[CTINFO2DIR(ctinfo)])
+				&& !(sctph.vtag == conntrack->proto.sctp.vtag
+							[1 - CTINFO2DIR(ctinfo)])) {
+				WRITE_UNLOCK(&sctp_lock);
+				return -1;
+			}
+		} else if (sch.type == SCTP_CID_SHUTDOWN_COMPLETE) {
+			/* Sec 8.5.1 (C) */
+			if (!(sctph.vtag == conntrack->proto.sctp.vtag[CTINFO2DIR(ctinfo)])
+				&& !(sctph.vtag == conntrack->proto.sctp.vtag
+							[1 - CTINFO2DIR(ctinfo)] 
+					&& (sch.flags & 1))) {
+				WRITE_UNLOCK(&sctp_lock);
+				return -1;
+			}
+		} else if (sch.type == SCTP_CID_COOKIE_ECHO) {
+			/* Sec 8.5.1 (D) */
+			if (!(sctph.vtag == conntrack->proto.sctp.vtag[CTINFO2DIR(ctinfo)])) {
+				WRITE_UNLOCK(&sctp_lock);
+				return -1;
+			}
+		}
+
+		oldsctpstate = conntrack->proto.sctp.state;
+		newconntrack = new_state(CTINFO2DIR(ctinfo), oldsctpstate, sch.type);
+
+		/* Invalid */
+		if (newconntrack == SCTP_CONNTRACK_MAX) {
+			DEBUGP("ip_conntrack_sctp: Invalid dir=%i ctype=%u conntrack=%u\n",
+			       CTINFO2DIR(ctinfo), sch.type, oldsctpstate);
+			WRITE_UNLOCK(&sctp_lock);
+			return -1;
+		}
+
+		/* If it is an INIT or an INIT ACK note down the vtag */
+		if (sch.type == SCTP_CID_INIT 
+			|| sch.type == SCTP_CID_INIT_ACK) {
+			sctp_inithdr_t inithdr;
+
+			if (skb_copy_bits(skb, offset + sizeof (sctp_chunkhdr_t),
+				&inithdr, sizeof(inithdr)) != 0) {
+					WRITE_UNLOCK(&sctp_lock);
+					return -1;
+			}
+			DEBUGP("Setting vtag %x for dir %d\n", 
+					inithdr.init_tag, CTINFO2DIR(ctinfo));
+			conntrack->proto.sctp.vtag[IP_CT_DIR_ORIGINAL] = inithdr.init_tag;
+		}
+
+		conntrack->proto.sctp.state = newconntrack;
+		WRITE_UNLOCK(&sctp_lock);
+	}
+
+	ip_ct_refresh(conntrack, *sctp_timeouts[newconntrack]);
+
+	if (oldsctpstate == SCTP_CONNTRACK_COOKIE_ECHOED
+		&& CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY
+		&& newconntrack == SCTP_CONNTRACK_ESTABLISHED) {
+		DEBUGP("Setting assured bit\n");
+		set_bit(IPS_ASSURED_BIT, &conntrack->status);
+	}
+
+	return NF_ACCEPT;
+}
+
+/* Called when a new connection for this protocol found. */
+static int sctp_new(struct ip_conntrack *conntrack, 
+		    const struct sk_buff *skb)
+{
+	enum sctp_conntrack newconntrack;
+	sctp_sctphdr_t sctph;
+	sctp_chunkhdr_t sch;
+	u_int32_t offset, count;
+	char map[256 / sizeof (char)] = {0};
+
+	DEBUGP(__FUNCTION__);
+	DEBUGP("\n");
+
+	if (skb_copy_bits(skb, skb->nh.iph->ihl * 4, &sctph, sizeof(sctph)) != 0)
+		return -1;
+
+	if (do_basic_checks(conntrack, skb, map) != 0)
+		return -1;
+
+	/* If an OOTB packet has any of these chunks discard (Sec 8.4) */
+	if ((test_bit (SCTP_CID_ABORT, (void *)map))
+		|| (test_bit (SCTP_CID_SHUTDOWN_COMPLETE, (void *)map))
+		|| (test_bit (SCTP_CID_COOKIE_ACK, (void *)map))) {
+		return -1;
+	}
+
+	newconntrack = SCTP_CONNTRACK_MAX;
+	for_each_sctp_chunk (skb, sch, offset, count) {
+		/* Don't need lock here: this conntrack not in circulation yet */
+		newconntrack = new_state (IP_CT_DIR_ORIGINAL, 
+						SCTP_CONNTRACK_NONE, sch.type);
+
+		/* Invalid: delete conntrack */
+		if (newconntrack == SCTP_CONNTRACK_MAX) {
+			DEBUGP("ip_conntrack_sctp: invalid new deleting.\n");
+			return 0;
+		}
+
+		/* Copy the vtag into the state info */
+		if (sch.type == SCTP_CID_INIT) {
+			if (sctph.vtag == 0) {
+				sctp_inithdr_t inithdr;
+
+				if (skb_copy_bits(skb, offset + sizeof (sctp_chunkhdr_t), 
+					&inithdr, sizeof(inithdr)) != 0) {
+						return -1;
+				}
+
+				DEBUGP("Setting vtag %x for new conn\n", 
+					inithdr.init_tag);
+
+				conntrack->proto.sctp.vtag[IP_CT_DIR_REPLY] = 
+								inithdr.init_tag;
+			} else {
+				/* Sec 8.5.1 (A) */
+				return -1;
+			}
+		}
+		/* If it is a shutdown ack OOTB packet, we expect a return
+		   shutdown complete, otherwise an ABORT Sec 8.4 (5) and (8) */
+		else {
+			DEBUGP("Setting vtag %x for new conn OOTB\n", 
+				sctph.vtag);
+			conntrack->proto.sctp.vtag[IP_CT_DIR_REPLY] = sctph.vtag;
+		}
+
+		conntrack->proto.sctp.state = newconntrack;
+	}
+
+	return 1;
+}
+
+static int sctp_exp_matches_pkt(struct ip_conntrack_expect *exp,
+				const struct sk_buff *skb)
+{
+	/* To be implemented */
+	return 0;
+}
+
+struct ip_conntrack_protocol ip_conntrack_protocol_sctp = { 
+	.list 		 = { NULL, NULL }, 
+	.proto 		 = IPPROTO_SCTP, 
+	.name 		 = "sctp",
+	.pkt_to_tuple 	 = sctp_pkt_to_tuple, 
+	.invert_tuple 	 = sctp_invert_tuple, 
+	.print_tuple 	 = sctp_print_tuple, 
+	.print_conntrack = sctp_print_conntrack,
+	.packet 	 = sctp_packet, 
+	.new 		 = sctp_new, 
+	.destroy 	 = NULL, 
+	.exp_matches_pkt = sctp_exp_matches_pkt, 
+	.me 		 = THIS_MODULE 
+};
+
+#ifdef CONFIG_SYSCTL
+static ctl_table ip_ct_sysctl_table[] = {
+	{
+		.ctl_name	= NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_CLOSED,
+		.procname	= "ip_conntrack_sctp_timeout_closed",
+		.data		= &ip_ct_sctp_timeout_closed,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_COOKIE_WAIT,
+		.procname	= "ip_conntrack_sctp_timeout_cookie_wait",
+		.data		= &ip_ct_sctp_timeout_cookie_wait,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_COOKIE_ECHOED,
+		.procname	= "ip_conntrack_sctp_timeout_cookie_echoed",
+		.data		= &ip_ct_sctp_timeout_cookie_echoed,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_ESTABLISHED,
+		.procname	= "ip_conntrack_sctp_timeout_established",
+		.data		= &ip_ct_sctp_timeout_established,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_SHUTDOWN_SENT,
+		.procname	= "ip_conntrack_sctp_timeout_shutdown_sent",
+		.data		= &ip_ct_sctp_timeout_shutdown_sent,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_SHUTDOWN_RECD,
+		.procname	= "ip_conntrack_sctp_timeout_shutdown_recd",
+		.data		= &ip_ct_sctp_timeout_shutdown_recd,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= NET_IPV4_NF_CONNTRACK_SCTP_TIMEOUT_SHUTDOWN_ACK_SENT,
+		.procname	= "ip_conntrack_sctp_timeout_shutdown_ack_sent",
+		.data		= &ip_ct_sctp_timeout_shutdown_ack_sent,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_jiffies,
+	},
+	{ .ctl_name = 0 }
+};
+
+static ctl_table ip_ct_netfilter_table[] = {
+	{
+		.ctl_name	= NET_IPV4_NETFILTER,
+		.procname	= "netfilter",
+		.mode		= 0555,
+		.child		= ip_ct_sysctl_table,
+	},
+	{ .ctl_name = 0 }
+};
+
+static ctl_table ip_ct_ipv4_table[] = {
+	{
+		.ctl_name	= NET_IPV4,
+		.procname	= "ipv4",
+		.mode		= 0555,
+		.child		= ip_ct_netfilter_table,
+	},
+	{ .ctl_name = 0 }
+};
+
+static ctl_table ip_ct_net_table[] = {
+	{
+		.ctl_name	= CTL_NET,
+		.procname	= "net",
+		.mode		= 0555, 
+		.child		= ip_ct_ipv4_table,
+	},
+	{ .ctl_name = 0 }
+};
+
+static struct ctl_table_header *ip_ct_sysctl_header;
+#endif
+
+int __init init(void)
+{
+	int ret;
+
+	ret = ip_conntrack_protocol_register(&ip_conntrack_protocol_sctp);
+	if (ret) {
+		printk("ip_conntrack_proto_sctp: protocol register failed\n");
+		goto out;
+	}
+
+#ifdef CONFIG_SYSCTL
+	ip_ct_sysctl_header = register_sysctl_table(ip_ct_net_table, 0);
+	if (ip_ct_sysctl_header == NULL) {
+		printk("ip_conntrack_proto_sctp: can't register to sysctl.\n");
+		goto cleanup;
+	}
+#endif
+
+	return ret;
+
+ cleanup:
+#ifdef CONFIG_SYSCTL
+	ip_conntrack_protocol_unregister(&ip_conntrack_protocol_sctp);
+#endif
+ out:
+	DEBUGP("SCTP conntrack module loading %s\n", 
+					ret ? "failed": "succeeded");
+	return ret;
+}
+
+void __exit fini(void)
+{
+	ip_conntrack_protocol_unregister(&ip_conntrack_protocol_sctp);
+#ifdef CONFIG_SYSCTL
+ 	unregister_sysctl_table(ip_ct_sysctl_header);
+#endif
+	DEBUGP("SCTP conntrack module unloaded\n");
+}
+
+module_init(init);
+module_exit(fini);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Kiran Kumar Immidi");
+MODULE_DESCRIPTION("Netfilter connection tracking protocol helper for SCTP");