[NETFILTER]: nf_conntrack: add DCCP protocol support

Add DCCP conntrack helper. Thanks to Gerrit Renker <gerrit@erg.abdn.ac.uk>
for review and testing.

Signed-off-by: Patrick McHardy <kaber@trash.net>

include/linux/netfilter/nf_conntrack_dccp.h

@@ -0,0 +1,40 @@
+#ifndef _NF_CONNTRACK_DCCP_H
+#define _NF_CONNTRACK_DCCP_H
+
+/* Exposed to userspace over nfnetlink */
+enum ct_dccp_states {
+	CT_DCCP_NONE,
+	CT_DCCP_REQUEST,
+	CT_DCCP_RESPOND,
+	CT_DCCP_PARTOPEN,
+	CT_DCCP_OPEN,
+	CT_DCCP_CLOSEREQ,
+	CT_DCCP_CLOSING,
+	CT_DCCP_TIMEWAIT,
+	CT_DCCP_IGNORE,
+	CT_DCCP_INVALID,
+	__CT_DCCP_MAX
+};
+#define CT_DCCP_MAX		(__CT_DCCP_MAX - 1)
+
+enum ct_dccp_roles {
+	CT_DCCP_ROLE_CLIENT,
+	CT_DCCP_ROLE_SERVER,
+	__CT_DCCP_ROLE_MAX
+};
+#define CT_DCCP_ROLE_MAX	(__CT_DCCP_ROLE_MAX - 1)
+
+#ifdef __KERNEL__
+#include <net/netfilter/nf_conntrack_tuple.h>
+
+struct nf_ct_dccp {
+	u_int8_t	role[IP_CT_DIR_MAX];
+	u_int8_t	state;
+	u_int8_t	last_pkt;
+	u_int8_t	last_dir;
+	u_int64_t	handshake_seq;
+};
+
+#endif /* __KERNEL__ */
+
+#endif /* _NF_CONNTRACK_DCCP_H */

include/linux/netfilter/nfnetlink_conntrack.h

@@ -80,6 +80,7 @@ enum ctattr_l4proto {
 enum ctattr_protoinfo {
 	CTA_PROTOINFO_UNSPEC,
 	CTA_PROTOINFO_TCP,
+	CTA_PROTOINFO_DCCP,
 	__CTA_PROTOINFO_MAX
 };
 #define CTA_PROTOINFO_MAX (__CTA_PROTOINFO_MAX - 1)
@@ -95,6 +96,13 @@ enum ctattr_protoinfo_tcp {
 };
 #define CTA_PROTOINFO_TCP_MAX (__CTA_PROTOINFO_TCP_MAX - 1)
 
+enum ctattr_protoinfo_dccp {
+	CTA_PROTOINFO_DCCP_UNSPEC,
+	CTA_PROTOINFO_DCCP_STATE,
+	__CTA_PROTOINFO_DCCP_MAX,
+};
+#define CTA_PROTOINFO_DCCP_MAX (__CTA_PROTOINFO_DCCP_MAX - 1)
+
 enum ctattr_counters {
 	CTA_COUNTERS_UNSPEC,
 	CTA_COUNTERS_PACKETS,		/* old 64bit counters */

include/net/netfilter/nf_conntrack.h

@@ -20,6 +20,7 @@
 #include <asm/atomic.h>
 
 #include <linux/netfilter/nf_conntrack_tcp.h>
+#include <linux/netfilter/nf_conntrack_dccp.h>
 #include <linux/netfilter/nf_conntrack_sctp.h>
 #include <linux/netfilter/nf_conntrack_proto_gre.h>
 #include <net/netfilter/ipv4/nf_conntrack_icmp.h>
@@ -30,6 +31,7 @@
 /* per conntrack: protocol private data */
 union nf_conntrack_proto {
 	/* insert conntrack proto private data here */
+	struct nf_ct_dccp dccp;
 	struct ip_ct_sctp sctp;
 	struct ip_ct_tcp tcp;
 	struct ip_ct_icmp icmp;

include/net/netfilter/nf_conntrack_tuple.h

@@ -39,6 +39,9 @@ union nf_conntrack_man_proto
 	struct {
 		__be16 id;
 	} icmp;
+	struct {
+		__be16 port;
+	} dccp;
 	struct {
 		__be16 port;
 	} sctp;
@@ -77,6 +80,9 @@ struct nf_conntrack_tuple
 			struct {
 				u_int8_t type, code;
 			} icmp;
+			struct {
+				__be16 port;
+			} dccp;
 			struct {
 				__be16 port;
 			} sctp;

net/netfilter/Kconfig

@@ -86,6 +86,16 @@ config NF_CONNTRACK_EVENTS
 
 	  If unsure, say `N'.
 
+config NF_CT_PROTO_DCCP
+	tristate 'DCCP protocol connection tracking support (EXPERIMENTAL)'
+	depends on EXPERIMENTAL && NF_CONNTRACK
+	depends on NETFILTER_ADVANCED
+	help
+	  With this option enabled, the layer 3 independent connection
+	  tracking code will be able to do state tracking on DCCP connections.
+
+	  If unsure, say 'N'.
+
 config NF_CT_PROTO_GRE
 	tristate
 	depends on NF_CONNTRACK

net/netfilter/Makefile

@@ -13,6 +13,7 @@ obj-$(CONFIG_NETFILTER_NETLINK_LOG) += nfnetlink_log.o
 obj-$(CONFIG_NF_CONNTRACK) += nf_conntrack.o
 
 # SCTP protocol connection tracking
+obj-$(CONFIG_NF_CT_PROTO_DCCP) += nf_conntrack_proto_dccp.o
 obj-$(CONFIG_NF_CT_PROTO_GRE) += nf_conntrack_proto_gre.o
 obj-$(CONFIG_NF_CT_PROTO_SCTP) += nf_conntrack_proto_sctp.o
 obj-$(CONFIG_NF_CT_PROTO_UDPLITE) += nf_conntrack_proto_udplite.o

net/netfilter/nf_conntrack_proto_dccp.c

@@ -0,0 +1,816 @@
+/*
+ * DCCP connection tracking protocol helper
+ *
+ * Copyright (c) 2005, 2006, 2008 Patrick McHardy <kaber@trash.net>
+ *
+ * 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/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <linux/spinlock.h>
+#include <linux/skbuff.h>
+#include <linux/dccp.h>
+
+#include <linux/netfilter/nfnetlink_conntrack.h>
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_l4proto.h>
+#include <net/netfilter/nf_log.h>
+
+static DEFINE_RWLOCK(dccp_lock);
+
+static int nf_ct_dccp_loose __read_mostly = 1;
+
+/* Timeouts are based on values from RFC4340:
+ *
+ * - REQUEST:
+ *
+ *   8.1.2. Client Request
+ *
+ *   A client MAY give up on its DCCP-Requests after some time
+ *   (3 minutes, for example).
+ *
+ * - RESPOND:
+ *
+ *   8.1.3. Server Response
+ *
+ *   It MAY also leave the RESPOND state for CLOSED after a timeout of
+ *   not less than 4MSL (8 minutes);
+ *
+ * - PARTOPEN:
+ *
+ *   8.1.5. Handshake Completion
+ *
+ *   If the client remains in PARTOPEN for more than 4MSL (8 minutes),
+ *   it SHOULD reset the connection with Reset Code 2, "Aborted".
+ *
+ * - OPEN:
+ *
+ *   The DCCP timestamp overflows after 11.9 hours. If the connection
+ *   stays idle this long the sequence number won't be recognized
+ *   as valid anymore.
+ *
+ * - CLOSEREQ/CLOSING:
+ *
+ *   8.3. Termination
+ *
+ *   The retransmission timer should initially be set to go off in two
+ *   round-trip times and should back off to not less than once every
+ *   64 seconds ...
+ *
+ * - TIMEWAIT:
+ *
+ *   4.3. States
+ *
+ *   A server or client socket remains in this state for 2MSL (4 minutes)
+ *   after the connection has been town down, ...
+ */
+
+#define DCCP_MSL (2 * 60 * HZ)
+
+static unsigned int dccp_timeout[CT_DCCP_MAX + 1] __read_mostly = {
+	[CT_DCCP_REQUEST]	= 2 * DCCP_MSL,
+	[CT_DCCP_RESPOND]	= 4 * DCCP_MSL,
+	[CT_DCCP_PARTOPEN]	= 4 * DCCP_MSL,
+	[CT_DCCP_OPEN]		= 12 * 3600 * HZ,
+	[CT_DCCP_CLOSEREQ]	= 64 * HZ,
+	[CT_DCCP_CLOSING]	= 64 * HZ,
+	[CT_DCCP_TIMEWAIT]	= 2 * DCCP_MSL,
+};
+
+static const char * const dccp_state_names[] = {
+	[CT_DCCP_NONE]		= "NONE",
+	[CT_DCCP_REQUEST]	= "REQUEST",
+	[CT_DCCP_RESPOND]	= "RESPOND",
+	[CT_DCCP_PARTOPEN]	= "PARTOPEN",
+	[CT_DCCP_OPEN]		= "OPEN",
+	[CT_DCCP_CLOSEREQ]	= "CLOSEREQ",
+	[CT_DCCP_CLOSING]	= "CLOSING",
+	[CT_DCCP_TIMEWAIT]	= "TIMEWAIT",
+	[CT_DCCP_IGNORE]	= "IGNORE",
+	[CT_DCCP_INVALID]	= "INVALID",
+};
+
+#define sNO	CT_DCCP_NONE
+#define sRQ	CT_DCCP_REQUEST
+#define sRS	CT_DCCP_RESPOND
+#define sPO	CT_DCCP_PARTOPEN
+#define sOP	CT_DCCP_OPEN
+#define sCR	CT_DCCP_CLOSEREQ
+#define sCG	CT_DCCP_CLOSING
+#define sTW	CT_DCCP_TIMEWAIT
+#define sIG	CT_DCCP_IGNORE
+#define sIV	CT_DCCP_INVALID
+
+/*
+ * DCCP state transistion table
+ *
+ * The assumption is the same as for TCP tracking:
+ *
+ * We are the man in the middle. All the packets go through us but might
+ * get lost in transit to the destination. It is assumed that the destination
+ * can't receive segments we haven't seen.
+ *
+ * The following states exist:
+ *
+ * NONE:	Initial state, expecting Request
+ * REQUEST:	Request seen, waiting for Response from server
+ * RESPOND:	Response from server seen, waiting for Ack from client
+ * PARTOPEN:	Ack after Response seen, waiting for packet other than Response,
+ * 		Reset or Sync from server
+ * OPEN:	Packet other than Response, Reset or Sync seen
+ * CLOSEREQ:	CloseReq from server seen, expecting Close from client
+ * CLOSING:	Close seen, expecting Reset
+ * TIMEWAIT:	Reset seen
+ * IGNORE:	Not determinable whether packet is valid
+ *
+ * Some states exist only on one side of the connection: REQUEST, RESPOND,
+ * PARTOPEN, CLOSEREQ. For the other side these states are equivalent to
+ * the one it was in before.
+ *
+ * Packets are marked as ignored (sIG) if we don't know if they're valid
+ * (for example a reincarnation of a connection we didn't notice is dead
+ * already) and the server may send back a connection closing Reset or a
+ * Response. They're also used for Sync/SyncAck packets, which we don't
+ * care about.
+ */
+static const u_int8_t
+dccp_state_table[CT_DCCP_ROLE_MAX + 1][DCCP_PKT_SYNCACK + 1][CT_DCCP_MAX + 1] = {
+	[CT_DCCP_ROLE_CLIENT] = {
+		[DCCP_PKT_REQUEST] = {
+		/*
+		 * sNO -> sRQ		Regular Request
+		 * sRQ -> sRQ		Retransmitted Request or reincarnation
+		 * sRS -> sRS		Retransmitted Request (apparently Response
+		 * 			got lost after we saw it) or reincarnation
+		 * sPO -> sIG		Ignore, conntrack might be out of sync
+		 * sOP -> sIG		Ignore, conntrack might be out of sync
+		 * sCR -> sIG		Ignore, conntrack might be out of sync
+		 * sCG -> sIG		Ignore, conntrack might be out of sync
+		 * sTW -> sRQ		Reincarnation
+		 *
+		 *	sNO, sRQ, sRS, sPO. sOP, sCR, sCG, sTW, */
+			sRQ, sRQ, sRS, sIG, sIG, sIG, sIG, sRQ,
+		},
+		[DCCP_PKT_RESPONSE] = {
+		/*
+		 * sNO -> sIV		Invalid
+		 * sRQ -> sIG		Ignore, might be response to ignored Request
+		 * sRS -> sIG		Ignore, might be response to ignored Request
+		 * sPO -> sIG		Ignore, might be response to ignored Request
+		 * sOP -> sIG		Ignore, might be response to ignored Request
+		 * sCR -> sIG		Ignore, might be response to ignored Request
+		 * sCG -> sIG		Ignore, might be response to ignored Request
+		 * sTW -> sIV		Invalid, reincarnation in reverse direction
+		 *			goes through sRQ
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIV,
+		},
+		[DCCP_PKT_ACK] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sIV		No connection
+		 * sRS -> sPO		Ack for Response, move to PARTOPEN (8.1.5.)
+		 * sPO -> sPO		Retransmitted Ack for Response, remain in PARTOPEN
+		 * sOP -> sOP		Regular ACK, remain in OPEN
+		 * sCR -> sCR		Ack in CLOSEREQ MAY be processed (8.3.)
+		 * sCG -> sCG		Ack in CLOSING MAY be processed (8.3.)
+		 * sTW -> sIV
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
+		},
+		[DCCP_PKT_DATA] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sIV		No connection
+		 * sRS -> sIV		No connection
+		 * sPO -> sIV		MUST use DataAck in PARTOPEN state (8.1.5.)
+		 * sOP -> sOP		Regular Data packet
+		 * sCR -> sCR		Data in CLOSEREQ MAY be processed (8.3.)
+		 * sCG -> sCG		Data in CLOSING MAY be processed (8.3.)
+		 * sTW -> sIV
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIV, sIV, sIV, sOP, sCR, sCG, sIV,
+		},
+		[DCCP_PKT_DATAACK] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sIV		No connection
+		 * sRS -> sPO		Ack for Response, move to PARTOPEN (8.1.5.)
+		 * sPO -> sPO		Remain in PARTOPEN state
+		 * sOP -> sOP		Regular DataAck packet in OPEN state
+		 * sCR -> sCR		DataAck in CLOSEREQ MAY be processed (8.3.)
+		 * sCG -> sCG		DataAck in CLOSING MAY be processed (8.3.)
+		 * sTW -> sIV
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
+		},
+		[DCCP_PKT_CLOSEREQ] = {
+		/*
+		 * CLOSEREQ may only be sent by the server.
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV
+		},
+		[DCCP_PKT_CLOSE] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sIV		No connection
+		 * sRS -> sIV		No connection
+		 * sPO -> sCG		Client-initiated close
+		 * sOP -> sCG		Client-initiated close
+		 * sCR -> sCG		Close in response to CloseReq (8.3.)
+		 * sCG -> sCG		Retransmit
+		 * sTW -> sIV		Late retransmit, already in TIME_WAIT
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIV, sIV, sCG, sCG, sCG, sIV, sIV
+		},
+		[DCCP_PKT_RESET] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sTW		Sync received or timeout, SHOULD send Reset (8.1.1.)
+		 * sRS -> sTW		Response received without Request
+		 * sPO -> sTW		Timeout, SHOULD send Reset (8.1.5.)
+		 * sOP -> sTW		Connection reset
+		 * sCR -> sTW		Connection reset
+		 * sCG -> sTW		Connection reset
+		 * sTW -> sIG		Ignore (don't refresh timer)
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sTW, sTW, sTW, sTW, sTW, sTW, sIG
+		},
+		[DCCP_PKT_SYNC] = {
+		/*
+		 * We currently ignore Sync packets
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
+		},
+		[DCCP_PKT_SYNCACK] = {
+		/*
+		 * We currently ignore SyncAck packets
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
+		},
+	},
+	[CT_DCCP_ROLE_SERVER] = {
+		[DCCP_PKT_REQUEST] = {
+		/*
+		 * sNO -> sIV		Invalid
+		 * sRQ -> sIG		Ignore, conntrack might be out of sync
+		 * sRS -> sIG		Ignore, conntrack might be out of sync
+		 * sPO -> sIG		Ignore, conntrack might be out of sync
+		 * sOP -> sIG		Ignore, conntrack might be out of sync
+		 * sCR -> sIG		Ignore, conntrack might be out of sync
+		 * sCG -> sIG		Ignore, conntrack might be out of sync
+		 * sTW -> sRQ		Reincarnation, must reverse roles
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIG, sIG, sIG, sIG, sIG, sIG, sRQ
+		},
+		[DCCP_PKT_RESPONSE] = {
+		/*
+		 * sNO -> sIV		Response without Request
+		 * sRQ -> sRS		Response to clients Request
+		 * sRS -> sRS		Retransmitted Response (8.1.3. SHOULD NOT)
+		 * sPO -> sIG		Response to an ignored Request or late retransmit
+		 * sOP -> sIG		Ignore, might be response to ignored Request
+		 * sCR -> sIG		Ignore, might be response to ignored Request
+		 * sCG -> sIG		Ignore, might be response to ignored Request
+		 * sTW -> sIV		Invalid, Request from client in sTW moves to sRQ
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sRS, sRS, sIG, sIG, sIG, sIG, sIV
+		},
+		[DCCP_PKT_ACK] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sIV		No connection
+		 * sRS -> sIV		No connection
+		 * sPO -> sOP		Enter OPEN state (8.1.5.)
+		 * sOP -> sOP		Regular Ack in OPEN state
+		 * sCR -> sIV		Waiting for Close from client
+		 * sCG -> sCG		Ack in CLOSING MAY be processed (8.3.)
+		 * sTW -> sIV
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
+		},
+		[DCCP_PKT_DATA] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sIV		No connection
+		 * sRS -> sIV		No connection
+		 * sPO -> sOP		Enter OPEN state (8.1.5.)
+		 * sOP -> sOP		Regular Data packet in OPEN state
+		 * sCR -> sIV		Waiting for Close from client
+		 * sCG -> sCG		Data in CLOSING MAY be processed (8.3.)
+		 * sTW -> sIV
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
+		},
+		[DCCP_PKT_DATAACK] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sIV		No connection
+		 * sRS -> sIV		No connection
+		 * sPO -> sOP		Enter OPEN state (8.1.5.)
+		 * sOP -> sOP		Regular DataAck in OPEN state
+		 * sCR -> sIV		Waiting for Close from client
+		 * sCG -> sCG		Data in CLOSING MAY be processed (8.3.)
+		 * sTW -> sIV
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
+		},
+		[DCCP_PKT_CLOSEREQ] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sIV		No connection
+		 * sRS -> sIV		No connection
+		 * sPO -> sOP -> sCR	Move directly to CLOSEREQ (8.1.5.)
+		 * sOP -> sCR		CloseReq in OPEN state
+		 * sCR -> sCR		Retransmit
+		 * sCG -> sCR		Simultaneous close, client sends another Close
+		 * sTW -> sIV		Already closed
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIV, sIV, sCR, sCR, sCR, sCR, sIV
+		},
+		[DCCP_PKT_CLOSE] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sIV		No connection
+		 * sRS -> sIV		No connection
+		 * sPO -> sOP -> sCG	Move direcly to CLOSING
+		 * sOP -> sCG		Move to CLOSING
+		 * sCR -> sIV		Close after CloseReq is invalid
+		 * sCG -> sCG		Retransmit
+		 * sTW -> sIV		Already closed
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIV, sIV, sIV, sCG, sCG, sIV, sCG, sIV
+		},
+		[DCCP_PKT_RESET] = {
+		/*
+		 * sNO -> sIV		No connection
+		 * sRQ -> sTW		Reset in response to Request
+		 * sRS -> sTW		Timeout, SHOULD send Reset (8.1.3.)
+		 * sPO -> sTW		Timeout, SHOULD send Reset (8.1.3.)
+		 * sOP -> sTW
+		 * sCR -> sTW
+		 * sCG -> sTW
+		 * sTW -> sIG		Ignore (don't refresh timer)
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW, sTW */
+			sIV, sTW, sTW, sTW, sTW, sTW, sTW, sTW, sIG
+		},
+		[DCCP_PKT_SYNC] = {
+		/*
+		 * We currently ignore Sync packets
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
+		},
+		[DCCP_PKT_SYNCACK] = {
+		/*
+		 * We currently ignore SyncAck packets
+		 *
+		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
+			sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
+		},
+	},
+};
+
+static int dccp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
+			     struct nf_conntrack_tuple *tuple)
+{
+	struct dccp_hdr _hdr, *dh;
+
+	dh = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
+	if (dh == NULL)
+		return 0;
+
+	tuple->src.u.dccp.port = dh->dccph_sport;
+	tuple->dst.u.dccp.port = dh->dccph_dport;
+	return 1;
+}
+
+static int dccp_invert_tuple(struct nf_conntrack_tuple *inv,
+			     const struct nf_conntrack_tuple *tuple)
+{
+	inv->src.u.dccp.port = tuple->dst.u.dccp.port;
+	inv->dst.u.dccp.port = tuple->src.u.dccp.port;
+	return 1;
+}
+
+static int dccp_new(struct nf_conn *ct, const struct sk_buff *skb,
+		    unsigned int dataoff)
+{
+	int pf = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
+	struct dccp_hdr _dh, *dh;
+	const char *msg;
+	u_int8_t state;
+
+	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
+	BUG_ON(dh == NULL);
+
+	state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
+	switch (state) {
+	default:
+		if (nf_ct_dccp_loose == 0) {
+			msg = "nf_ct_dccp: not picking up existing connection ";
+			goto out_invalid;
+		}
+	case CT_DCCP_REQUEST:
+		break;
+	case CT_DCCP_INVALID:
+		msg = "nf_ct_dccp: invalid state transition ";
+		goto out_invalid;
+	}
+
+	ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
+	ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
+	ct->proto.dccp.state = CT_DCCP_NONE;
+	return 1;
+
+out_invalid:
+	if (LOG_INVALID(IPPROTO_DCCP))
+		nf_log_packet(pf, 0, skb, NULL, NULL, NULL, msg);
+	return 0;
+}
+
+static u64 dccp_ack_seq(const struct dccp_hdr *dh)
+{
+	const struct dccp_hdr_ack_bits *dhack;
+
+	dhack = (void *)dh + __dccp_basic_hdr_len(dh);
+	return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) +
+		     ntohl(dhack->dccph_ack_nr_low);
+}
+
+static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb,
+		       unsigned int dataoff, enum ip_conntrack_info ctinfo,
+		       int pf, unsigned int hooknum)
+{
+	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+	struct dccp_hdr _dh, *dh;
+	u_int8_t type, old_state, new_state;
+	enum ct_dccp_roles role;
+
+	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
+	BUG_ON(dh == NULL);
+	type = dh->dccph_type;
+
+	if (type == DCCP_PKT_RESET &&
+	    !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
+		/* Tear down connection immediately if only reply is a RESET */
+		if (del_timer(&ct->timeout))
+			ct->timeout.function((unsigned long)ct);
+		return NF_ACCEPT;
+	}
+
+	write_lock_bh(&dccp_lock);
+
+	role = ct->proto.dccp.role[dir];
+	old_state = ct->proto.dccp.state;
+	new_state = dccp_state_table[role][type][old_state];
+
+	switch (new_state) {
+	case CT_DCCP_REQUEST:
+		if (old_state == CT_DCCP_TIMEWAIT &&
+		    role == CT_DCCP_ROLE_SERVER) {
+			/* Reincarnation in the reverse direction: reopen and
+			 * reverse client/server roles. */
+			ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
+			ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
+		}
+		break;
+	case CT_DCCP_RESPOND:
+		if (old_state == CT_DCCP_REQUEST)
+			ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
+		break;
+	case CT_DCCP_PARTOPEN:
+		if (old_state == CT_DCCP_RESPOND &&
+		    type == DCCP_PKT_ACK &&
+		    dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
+			set_bit(IPS_ASSURED_BIT, &ct->status);
+		break;
+	case CT_DCCP_IGNORE:
+		/*
+		 * Connection tracking might be out of sync, so we ignore
+		 * packets that might establish a new connection and resync
+		 * if the server responds with a valid Response.
+		 */
+		if (ct->proto.dccp.last_dir == !dir &&
+		    ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
+		    type == DCCP_PKT_RESPONSE) {
+			ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
+			ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
+			ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
+			new_state = CT_DCCP_RESPOND;
+			break;
+		}
+		ct->proto.dccp.last_dir = dir;
+		ct->proto.dccp.last_pkt = type;
+
+		write_unlock_bh(&dccp_lock);
+		if (LOG_INVALID(IPPROTO_DCCP))
+			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
+				      "nf_ct_dccp: invalid packet ignored ");
+		return NF_ACCEPT;
+	case CT_DCCP_INVALID:
+		write_unlock_bh(&dccp_lock);
+		if (LOG_INVALID(IPPROTO_DCCP))
+			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
+				      "nf_ct_dccp: invalid state transition ");
+		return -NF_ACCEPT;
+	}
+
+	ct->proto.dccp.last_dir = dir;
+	ct->proto.dccp.last_pkt = type;
+	ct->proto.dccp.state = new_state;
+	write_unlock_bh(&dccp_lock);
+	nf_ct_refresh_acct(ct, ctinfo, skb, dccp_timeout[new_state]);
+
+	return NF_ACCEPT;
+}
+
+static int dccp_error(struct sk_buff *skb, unsigned int dataoff,
+		      enum ip_conntrack_info *ctinfo, int pf,
+		      unsigned int hooknum)
+{
+	struct dccp_hdr _dh, *dh;
+	unsigned int dccp_len = skb->len - dataoff;
+	unsigned int cscov;
+	const char *msg;
+
+	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
+	if (dh == NULL) {
+		msg = "nf_ct_dccp: short packet ";
+		goto out_invalid;
+	}
+
+	if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) ||
+	    dh->dccph_doff * 4 > dccp_len) {
+		msg = "nf_ct_dccp: truncated/malformed packet ";
+		goto out_invalid;
+	}
+
+	cscov = dccp_len;
+	if (dh->dccph_cscov) {
+		cscov = (dh->dccph_cscov - 1) * 4;
+		if (cscov > dccp_len) {
+			msg = "nf_ct_dccp: bad checksum coverage ";
+			goto out_invalid;
+		}
+	}
+
+	if (nf_conntrack_checksum && hooknum == NF_INET_PRE_ROUTING &&
+	    nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_DCCP,
+				pf)) {
+		msg = "nf_ct_dccp: bad checksum ";
+		goto out_invalid;
+	}
+
+	if (dh->dccph_type >= DCCP_PKT_INVALID) {
+		msg = "nf_ct_dccp: reserved packet type ";
+		goto out_invalid;
+	}
+
+	return NF_ACCEPT;
+
+out_invalid:
+	if (LOG_INVALID(IPPROTO_DCCP))
+		nf_log_packet(pf, 0, skb, NULL, NULL, NULL, msg);
+	return -NF_ACCEPT;
+}
+
+static int dccp_print_tuple(struct seq_file *s,
+			    const struct nf_conntrack_tuple *tuple)
+{
+	return seq_printf(s, "sport=%hu dport=%hu ",
+			  ntohs(tuple->src.u.dccp.port),
+			  ntohs(tuple->dst.u.dccp.port));
+}
+
+static int dccp_print_conntrack(struct seq_file *s, const struct nf_conn *ct)
+{
+	return seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]);
+}
+
+#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
+static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
+			  const struct nf_conn *ct)
+{
+	struct nlattr *nest_parms;
+
+	read_lock_bh(&dccp_lock);
+	nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP | NLA_F_NESTED);
+	if (!nest_parms)
+		goto nla_put_failure;
+	NLA_PUT_U8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state);
+	nla_nest_end(skb, nest_parms);
+	read_unlock_bh(&dccp_lock);
+	return 0;
+
+nla_put_failure:
+	read_unlock_bh(&dccp_lock);
+	return -1;
+}
+
+static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = {
+	[CTA_PROTOINFO_DCCP_STATE]	= { .type = NLA_U8 },
+};
+
+static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct)
+{
+	struct nlattr *attr = cda[CTA_PROTOINFO_DCCP];
+	struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1];
+	int err;
+
+	if (!attr)
+		return 0;
+
+	err = nla_parse_nested(tb, CTA_PROTOINFO_DCCP_MAX, attr,
+			       dccp_nla_policy);
+	if (err < 0)
+		return err;
+
+	if (!tb[CTA_PROTOINFO_DCCP_STATE] ||
+	    nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE)
+		return -EINVAL;
+
+	write_lock_bh(&dccp_lock);
+	ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]);
+	write_unlock_bh(&dccp_lock);
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_SYSCTL
+static unsigned int dccp_sysctl_table_users;
+static struct ctl_table_header *dccp_sysctl_header;
+static ctl_table dccp_sysctl_table[] = {
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nf_conntrack_dccp_timeout_request",
+		.data		= &dccp_timeout[CT_DCCP_REQUEST],
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nf_conntrack_dccp_timeout_respond",
+		.data		= &dccp_timeout[CT_DCCP_RESPOND],
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nf_conntrack_dccp_timeout_partopen",
+		.data		= &dccp_timeout[CT_DCCP_PARTOPEN],
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nf_conntrack_dccp_timeout_open",
+		.data		= &dccp_timeout[CT_DCCP_OPEN],
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nf_conntrack_dccp_timeout_closereq",
+		.data		= &dccp_timeout[CT_DCCP_CLOSEREQ],
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nf_conntrack_dccp_timeout_closing",
+		.data		= &dccp_timeout[CT_DCCP_CLOSING],
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nf_conntrack_dccp_timeout_timewait",
+		.data		= &dccp_timeout[CT_DCCP_TIMEWAIT],
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nf_conntrack_dccp_loose",
+		.data		= &nf_ct_dccp_loose,
+		.maxlen		= sizeof(nf_ct_dccp_loose),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.ctl_name	= 0,
+	}
+};
+#endif /* CONFIG_SYSCTL */
+
+static struct nf_conntrack_l4proto dccp_proto4 __read_mostly = {
+	.l3proto		= AF_INET,
+	.l4proto		= IPPROTO_DCCP,
+	.name			= "dccp",
+	.pkt_to_tuple		= dccp_pkt_to_tuple,
+	.invert_tuple		= dccp_invert_tuple,
+	.new			= dccp_new,
+	.packet			= dccp_packet,
+	.error			= dccp_error,
+	.print_tuple		= dccp_print_tuple,
+	.print_conntrack	= dccp_print_conntrack,
+#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
+	.to_nlattr		= dccp_to_nlattr,
+	.from_nlattr		= nlattr_to_dccp,
+	.tuple_to_nlattr	= nf_ct_port_tuple_to_nlattr,
+	.nlattr_to_tuple	= nf_ct_port_nlattr_to_tuple,
+	.nla_policy		= nf_ct_port_nla_policy,
+#endif
+#ifdef CONFIG_SYSCTL
+	.ctl_table_users	= &dccp_sysctl_table_users,
+	.ctl_table_header	= &dccp_sysctl_header,
+	.ctl_table		= dccp_sysctl_table,
+#endif
+};
+
+static struct nf_conntrack_l4proto dccp_proto6 __read_mostly = {
+	.l3proto		= AF_INET6,
+	.l4proto		= IPPROTO_DCCP,
+	.name			= "dccp",
+	.pkt_to_tuple		= dccp_pkt_to_tuple,
+	.invert_tuple		= dccp_invert_tuple,
+	.new			= dccp_new,
+	.packet			= dccp_packet,
+	.error			= dccp_error,
+	.print_tuple		= dccp_print_tuple,
+	.print_conntrack	= dccp_print_conntrack,
+#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
+	.to_nlattr		= dccp_to_nlattr,
+	.from_nlattr		= nlattr_to_dccp,
+	.tuple_to_nlattr	= nf_ct_port_tuple_to_nlattr,
+	.nlattr_to_tuple	= nf_ct_port_nlattr_to_tuple,
+	.nla_policy		= nf_ct_port_nla_policy,
+#endif
+#ifdef CONFIG_SYSCTL
+	.ctl_table_users	= &dccp_sysctl_table_users,
+	.ctl_table_header	= &dccp_sysctl_header,
+	.ctl_table		= dccp_sysctl_table,
+#endif
+};
+
+static int __init nf_conntrack_proto_dccp_init(void)
+{
+	int err;
+
+	err = nf_conntrack_l4proto_register(&dccp_proto4);
+	if (err < 0)
+		goto err1;
+
+	err = nf_conntrack_l4proto_register(&dccp_proto6);
+	if (err < 0)
+		goto err2;
+	return 0;
+
+err2:
+	nf_conntrack_l4proto_unregister(&dccp_proto4);
+err1:
+	return err;
+}
+
+static void __exit nf_conntrack_proto_dccp_fini(void)
+{
+	nf_conntrack_l4proto_unregister(&dccp_proto6);
+	nf_conntrack_l4proto_unregister(&dccp_proto4);
+}
+
+module_init(nf_conntrack_proto_dccp_init);
+module_exit(nf_conntrack_proto_dccp_fini);
+
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_DESCRIPTION("DCCP connection tracking protocol helper");
+MODULE_LICENSE("GPL");