15 files changed, 1896 insertions, 0 deletions

diff --git a/include/linux/netfilter/nf_conntrack_pptp.h b/include/linux/netfilter/nf_conntrack_pptp.h
new file mode 100644
index 000000000000..fb049ec11ff2
--- /dev/null
+++ b/include/linux/netfilter/nf_conntrack_pptp.h
@@ -0,0 +1,321 @@
+/* PPTP constants and structs */
+#ifndef _NF_CONNTRACK_PPTP_H
+#define _NF_CONNTRACK_PPTP_H
+
+/* state of the control session */
+enum pptp_ctrlsess_state {
+	PPTP_SESSION_NONE,			/* no session present */
+	PPTP_SESSION_ERROR,			/* some session error */
+	PPTP_SESSION_STOPREQ,			/* stop_sess request seen */
+	PPTP_SESSION_REQUESTED,			/* start_sess request seen */
+	PPTP_SESSION_CONFIRMED,			/* session established */
+};
+
+/* state of the call inside the control session */
+enum pptp_ctrlcall_state {
+	PPTP_CALL_NONE,
+	PPTP_CALL_ERROR,
+	PPTP_CALL_OUT_REQ,
+	PPTP_CALL_OUT_CONF,
+	PPTP_CALL_IN_REQ,
+	PPTP_CALL_IN_REP,
+	PPTP_CALL_IN_CONF,
+	PPTP_CALL_CLEAR_REQ,
+};
+
+/* conntrack private data */
+struct nf_ct_pptp_master {
+	enum pptp_ctrlsess_state sstate;	/* session state */
+	enum pptp_ctrlcall_state cstate;	/* call state */
+	__be16 pac_call_id;			/* call id of PAC */
+	__be16 pns_call_id;			/* call id of PNS */
+
+	/* in pre-2.6.11 this used to be per-expect. Now it is per-conntrack
+	 * and therefore imposes a fixed limit on the number of maps */
+	struct nf_ct_gre_keymap *keymap[IP_CT_DIR_MAX];
+};
+
+struct nf_nat_pptp {
+	__be16 pns_call_id;			/* NAT'ed PNS call id */
+	__be16 pac_call_id;			/* NAT'ed PAC call id */
+};
+
+#ifdef __KERNEL__
+
+#define PPTP_CONTROL_PORT	1723
+
+#define PPTP_PACKET_CONTROL	1
+#define PPTP_PACKET_MGMT	2
+
+#define PPTP_MAGIC_COOKIE	0x1a2b3c4d
+
+struct pptp_pkt_hdr {
+	__u16	packetLength;
+	__be16	packetType;
+	__be32	magicCookie;
+};
+
+/* PptpControlMessageType values */
+#define PPTP_START_SESSION_REQUEST	1
+#define PPTP_START_SESSION_REPLY	2
+#define PPTP_STOP_SESSION_REQUEST	3
+#define PPTP_STOP_SESSION_REPLY		4
+#define PPTP_ECHO_REQUEST		5
+#define PPTP_ECHO_REPLY			6
+#define PPTP_OUT_CALL_REQUEST		7
+#define PPTP_OUT_CALL_REPLY		8
+#define PPTP_IN_CALL_REQUEST		9
+#define PPTP_IN_CALL_REPLY		10
+#define PPTP_IN_CALL_CONNECT		11
+#define PPTP_CALL_CLEAR_REQUEST		12
+#define PPTP_CALL_DISCONNECT_NOTIFY	13
+#define PPTP_WAN_ERROR_NOTIFY		14
+#define PPTP_SET_LINK_INFO		15
+
+#define PPTP_MSG_MAX			15
+
+/* PptpGeneralError values */
+#define PPTP_ERROR_CODE_NONE		0
+#define PPTP_NOT_CONNECTED		1
+#define PPTP_BAD_FORMAT			2
+#define PPTP_BAD_VALUE			3
+#define PPTP_NO_RESOURCE		4
+#define PPTP_BAD_CALLID			5
+#define PPTP_REMOVE_DEVICE_ERROR	6
+
+struct PptpControlHeader {
+	__be16	messageType;
+	__u16	reserved;
+};
+
+/* FramingCapability Bitmap Values */
+#define PPTP_FRAME_CAP_ASYNC		0x1
+#define PPTP_FRAME_CAP_SYNC		0x2
+
+/* BearerCapability Bitmap Values */
+#define PPTP_BEARER_CAP_ANALOG		0x1
+#define PPTP_BEARER_CAP_DIGITAL		0x2
+
+struct PptpStartSessionRequest {
+	__be16	protocolVersion;
+	__u16	reserved1;
+	__be32	framingCapability;
+	__be32	bearerCapability;
+	__be16	maxChannels;
+	__be16	firmwareRevision;
+	__u8	hostName[64];
+	__u8	vendorString[64];
+};
+
+/* PptpStartSessionResultCode Values */
+#define PPTP_START_OK			1
+#define PPTP_START_GENERAL_ERROR	2
+#define PPTP_START_ALREADY_CONNECTED	3
+#define PPTP_START_NOT_AUTHORIZED	4
+#define PPTP_START_UNKNOWN_PROTOCOL	5
+
+struct PptpStartSessionReply {
+	__be16	protocolVersion;
+	__u8	resultCode;
+	__u8	generalErrorCode;
+	__be32	framingCapability;
+	__be32	bearerCapability;
+	__be16	maxChannels;
+	__be16	firmwareRevision;
+	__u8	hostName[64];
+	__u8	vendorString[64];
+};
+
+/* PptpStopReasons */
+#define PPTP_STOP_NONE			1
+#define PPTP_STOP_PROTOCOL		2
+#define PPTP_STOP_LOCAL_SHUTDOWN	3
+
+struct PptpStopSessionRequest {
+	__u8	reason;
+	__u8	reserved1;
+	__u16	reserved2;
+};
+
+/* PptpStopSessionResultCode */
+#define PPTP_STOP_OK			1
+#define PPTP_STOP_GENERAL_ERROR		2
+
+struct PptpStopSessionReply {
+	__u8	resultCode;
+	__u8	generalErrorCode;
+	__u16	reserved1;
+};
+
+struct PptpEchoRequest {
+	__be32 identNumber;
+};
+
+/* PptpEchoReplyResultCode */
+#define PPTP_ECHO_OK			1
+#define PPTP_ECHO_GENERAL_ERROR		2
+
+struct PptpEchoReply {
+	__be32	identNumber;
+	__u8	resultCode;
+	__u8	generalErrorCode;
+	__u16	reserved;
+};
+
+/* PptpFramingType */
+#define PPTP_ASYNC_FRAMING		1
+#define PPTP_SYNC_FRAMING		2
+#define PPTP_DONT_CARE_FRAMING		3
+
+/* PptpCallBearerType */
+#define PPTP_ANALOG_TYPE		1
+#define PPTP_DIGITAL_TYPE		2
+#define PPTP_DONT_CARE_BEARER_TYPE	3
+
+struct PptpOutCallRequest {
+	__be16	callID;
+	__be16	callSerialNumber;
+	__be32	minBPS;
+	__be32	maxBPS;
+	__be32	bearerType;
+	__be32	framingType;
+	__be16	packetWindow;
+	__be16	packetProcDelay;
+	__be16	phoneNumberLength;
+	__u16	reserved1;
+	__u8	phoneNumber[64];
+	__u8	subAddress[64];
+};
+
+/* PptpCallResultCode */
+#define PPTP_OUTCALL_CONNECT		1
+#define PPTP_OUTCALL_GENERAL_ERROR	2
+#define PPTP_OUTCALL_NO_CARRIER		3
+#define PPTP_OUTCALL_BUSY		4
+#define PPTP_OUTCALL_NO_DIAL_TONE	5
+#define PPTP_OUTCALL_TIMEOUT		6
+#define PPTP_OUTCALL_DONT_ACCEPT	7
+
+struct PptpOutCallReply {
+	__be16	callID;
+	__be16	peersCallID;
+	__u8	resultCode;
+	__u8	generalErrorCode;
+	__be16	causeCode;
+	__be32	connectSpeed;
+	__be16	packetWindow;
+	__be16	packetProcDelay;
+	__be32	physChannelID;
+};
+
+struct PptpInCallRequest {
+	__be16	callID;
+	__be16	callSerialNumber;
+	__be32	callBearerType;
+	__be32	physChannelID;
+	__be16	dialedNumberLength;
+	__be16	dialingNumberLength;
+	__u8	dialedNumber[64];
+	__u8	dialingNumber[64];
+	__u8	subAddress[64];
+};
+
+/* PptpInCallResultCode */
+#define PPTP_INCALL_ACCEPT		1
+#define PPTP_INCALL_GENERAL_ERROR	2
+#define PPTP_INCALL_DONT_ACCEPT		3
+
+struct PptpInCallReply {
+	__be16	callID;
+	__be16	peersCallID;
+	__u8	resultCode;
+	__u8	generalErrorCode;
+	__be16	packetWindow;
+	__be16	packetProcDelay;
+	__u16	reserved;
+};
+
+struct PptpInCallConnected {
+	__be16	peersCallID;
+	__u16	reserved;
+	__be32	connectSpeed;
+	__be16	packetWindow;
+	__be16	packetProcDelay;
+	__be32	callFramingType;
+};
+
+struct PptpClearCallRequest {
+	__be16	callID;
+	__u16	reserved;
+};
+
+struct PptpCallDisconnectNotify {
+	__be16	callID;
+	__u8	resultCode;
+	__u8	generalErrorCode;
+	__be16	causeCode;
+	__u16	reserved;
+	__u8	callStatistics[128];
+};
+
+struct PptpWanErrorNotify {
+	__be16	peersCallID;
+	__u16	reserved;
+	__be32	crcErrors;
+	__be32	framingErrors;
+	__be32	hardwareOverRuns;
+	__be32	bufferOverRuns;
+	__be32	timeoutErrors;
+	__be32	alignmentErrors;
+};
+
+struct PptpSetLinkInfo {
+	__be16	peersCallID;
+	__u16	reserved;
+	__be32	sendAccm;
+	__be32	recvAccm;
+};
+
+union pptp_ctrl_union {
+	struct PptpStartSessionRequest	sreq;
+	struct PptpStartSessionReply	srep;
+	struct PptpStopSessionRequest	streq;
+	struct PptpStopSessionReply	strep;
+	struct PptpOutCallRequest	ocreq;
+	struct PptpOutCallReply		ocack;
+	struct PptpInCallRequest	icreq;
+	struct PptpInCallReply		icack;
+	struct PptpInCallConnected	iccon;
+	struct PptpClearCallRequest	clrreq;
+	struct PptpCallDisconnectNotify disc;
+	struct PptpWanErrorNotify	wanerr;
+	struct PptpSetLinkInfo		setlink;
+};
+
+/* crap needed for nf_conntrack_compat.h */
+struct nf_conn;
+struct nf_conntrack_expect;
+enum ip_conntrack_info;
+
+extern int
+(*nf_nat_pptp_hook_outbound)(struct sk_buff **pskb,
+			     struct nf_conn *ct, enum ip_conntrack_info ctinfo,
+			     struct PptpControlHeader *ctlh,
+			     union pptp_ctrl_union *pptpReq);
+
+extern int
+(*nf_nat_pptp_hook_inbound)(struct sk_buff **pskb,
+			    struct nf_conn *ct, enum ip_conntrack_info ctinfo,
+			    struct PptpControlHeader *ctlh,
+			    union pptp_ctrl_union *pptpReq);
+
+extern void
+(*nf_nat_pptp_hook_exp_gre)(struct nf_conntrack_expect *exp_orig,
+			    struct nf_conntrack_expect *exp_reply);
+
+extern void
+(*nf_nat_pptp_hook_expectfn)(struct nf_conn *ct,
+			     struct nf_conntrack_expect *exp);
+
+#endif /* __KERNEL__ */
+#endif /* _NF_CONNTRACK_PPTP_H */
diff --git a/include/linux/netfilter/nf_conntrack_proto_gre.h b/include/linux/netfilter/nf_conntrack_proto_gre.h
new file mode 100644
index 000000000000..4e6bbce04ff8
--- /dev/null
+++ b/include/linux/netfilter/nf_conntrack_proto_gre.h
@@ -0,0 +1,112 @@
+#ifndef _CONNTRACK_PROTO_GRE_H
+#define _CONNTRACK_PROTO_GRE_H
+#include <asm/byteorder.h>
+
+/* GRE PROTOCOL HEADER */
+
+/* GRE Version field */
+#define GRE_VERSION_1701	0x0
+#define GRE_VERSION_PPTP	0x1
+
+/* GRE Protocol field */
+#define GRE_PROTOCOL_PPTP	0x880B
+
+/* GRE Flags */
+#define GRE_FLAG_C		0x80
+#define GRE_FLAG_R		0x40
+#define GRE_FLAG_K		0x20
+#define GRE_FLAG_S		0x10
+#define GRE_FLAG_A		0x80
+
+#define GRE_IS_C(f)	((f)&GRE_FLAG_C)
+#define GRE_IS_R(f)	((f)&GRE_FLAG_R)
+#define GRE_IS_K(f)	((f)&GRE_FLAG_K)
+#define GRE_IS_S(f)	((f)&GRE_FLAG_S)
+#define GRE_IS_A(f)	((f)&GRE_FLAG_A)
+
+/* GRE is a mess: Four different standards */
+struct gre_hdr {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u16	rec:3,
+		srr:1,
+		seq:1,
+		key:1,
+		routing:1,
+		csum:1,
+		version:3,
+		reserved:4,
+		ack:1;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u16	csum:1,
+		routing:1,
+		key:1,
+		seq:1,
+		srr:1,
+		rec:3,
+		ack:1,
+		reserved:4,
+		version:3;
+#else
+#error "Adjust your <asm/byteorder.h> defines"
+#endif
+	__be16	protocol;
+};
+
+/* modified GRE header for PPTP */
+struct gre_hdr_pptp {
+	__u8   flags;		/* bitfield */
+	__u8   version;		/* should be GRE_VERSION_PPTP */
+	__be16 protocol;	/* should be GRE_PROTOCOL_PPTP */
+	__be16 payload_len;	/* size of ppp payload, not inc. gre header */
+	__be16 call_id;		/* peer's call_id for this session */
+	__be32 seq;		/* sequence number.  Present if S==1 */
+	__be32 ack;		/* seq number of highest packet recieved by */
+				/*  sender in this session */
+};
+
+struct nf_ct_gre {
+	unsigned int stream_timeout;
+	unsigned int timeout;
+};
+
+#ifdef __KERNEL__
+#include <net/netfilter/nf_conntrack_tuple.h>
+
+struct nf_conn;
+
+/* structure for original <-> reply keymap */
+struct nf_ct_gre_keymap {
+	struct list_head list;
+	struct nf_conntrack_tuple tuple;
+};
+
+/* add new tuple->key_reply pair to keymap */
+int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
+			 struct nf_conntrack_tuple *t);
+
+/* delete keymap entries */
+void nf_ct_gre_keymap_destroy(struct nf_conn *ct);
+
+/* get pointer to gre key, if present */
+static inline __be32 *gre_key(struct gre_hdr *greh)
+{
+	if (!greh->key)
+		return NULL;
+	if (greh->csum || greh->routing)
+		return (__be32 *)(greh+sizeof(*greh)+4);
+	return (__be32 *)(greh+sizeof(*greh));
+}
+
+/* get pointer ot gre csum, if present */
+static inline __sum16 *gre_csum(struct gre_hdr *greh)
+{
+	if (!greh->csum)
+		return NULL;
+	return (__sum16 *)(greh+sizeof(*greh));
+}
+
+extern void nf_ct_gre_keymap_flush(void);
+extern void nf_nat_need_gre(void);
+
+#endif /* __KERNEL__ */
+#endif /* _CONNTRACK_PROTO_GRE_H */
diff --git a/include/net/netfilter/ipv4/nf_conntrack_ipv4.h b/include/net/netfilter/ipv4/nf_conntrack_ipv4.h
index a1c57ee0a4fa..1401ccc051c4 100644
--- a/include/net/netfilter/ipv4/nf_conntrack_ipv4.h
+++ b/include/net/netfilter/ipv4/nf_conntrack_ipv4.h
@@ -11,10 +11,12 @@
 
 #ifdef CONFIG_NF_NAT_NEEDED
 #include <net/netfilter/nf_nat.h>
+#include <linux/netfilter/nf_conntrack_pptp.h>
 
 /* per conntrack: nat application helper private data */
 union nf_conntrack_nat_help {
         /* insert nat helper private data here */
+	struct nf_nat_pptp nat_pptp_info;
 };
 
 struct nf_conn_nat {
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 1646076933b1..032b36a0e378 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -21,6 +21,7 @@
 
 #include <linux/netfilter/nf_conntrack_tcp.h>
 #include <linux/netfilter/nf_conntrack_sctp.h>
+#include <linux/netfilter/nf_conntrack_proto_gre.h>
 #include <net/netfilter/ipv4/nf_conntrack_icmp.h>
 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
 
@@ -33,6 +34,7 @@ union nf_conntrack_proto {
 	struct ip_ct_tcp tcp;
 	struct ip_ct_icmp icmp;
 	struct nf_ct_icmpv6 icmpv6;
+	struct nf_ct_gre gre;
 };
 
 union nf_conntrack_expect_proto {
@@ -41,12 +43,14 @@ union nf_conntrack_expect_proto {
 
 /* Add protocol helper include file here */
 #include <linux/netfilter/nf_conntrack_ftp.h>
+#include <linux/netfilter/nf_conntrack_pptp.h>
 #include <linux/netfilter/nf_conntrack_h323.h>
 
 /* per conntrack: application helper private data */
 union nf_conntrack_help {
 	/* insert conntrack helper private data (master) here */
 	struct nf_ct_ftp_master ct_ftp_info;
+	struct nf_ct_pptp_master ct_pptp_info;
 	struct nf_ct_h323_master ct_h323_info;
 };
 
diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index fbba9e8b95fc..8c72ac9f0ab8 100644
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -34,6 +34,8 @@ struct nf_conntrack_helper
 		    struct nf_conn *ct,
 		    enum ip_conntrack_info conntrackinfo);
 
+	void (*destroy)(struct nf_conn *ct);
+
 	int (*to_nfattr)(struct sk_buff *skb, const struct nf_conn *ct);
 };
 
diff --git a/include/net/netfilter/nf_conntrack_tuple.h b/include/net/netfilter/nf_conntrack_tuple.h
index c96a9c576736..5d72b16e876f 100644
--- a/include/net/netfilter/nf_conntrack_tuple.h
+++ b/include/net/netfilter/nf_conntrack_tuple.h
@@ -49,6 +49,9 @@ union nf_conntrack_man_proto
 	struct {
 		__be16 port;
 	} sctp;
+	struct {
+		__be16 key;	/* GRE key is 32bit, PPtP only uses 16bit */
+	} gre;
 };
 
 /* The manipulable part of the tuple. */
@@ -84,6 +87,9 @@ struct nf_conntrack_tuple
 			struct {
 				__be16 port;
 			} sctp;
+			struct {
+				__be16 key;
+			} gre;
 		} u;
 
 		/* The protocol. */
diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 4555f721dfc1..c3327ac024de 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -484,6 +484,10 @@ config IP_NF_NAT_SNMP_BASIC
 #           <expr> '&&' <expr>                   (6)
 #
 # (6) Returns the result of min(/expr/, /expr/).
+config NF_NAT_PROTO_GRE
+	tristate
+	depends on NF_NAT && NF_CT_PROTO_GRE
+
 config IP_NF_NAT_FTP
 	tristate
 	depends on IP_NF_IPTABLES && IP_NF_CONNTRACK && IP_NF_NAT
@@ -528,6 +532,12 @@ config IP_NF_NAT_PPTP
 	default IP_NF_NAT if IP_NF_PPTP=y
 	default m if IP_NF_PPTP=m
 
+config NF_NAT_PPTP
+	tristate
+	depends on IP_NF_IPTABLES && NF_CONNTRACK && NF_NAT
+	default NF_NAT && NF_CONNTRACK_PPTP
+	select NF_NAT_PROTO_GRE
+
 config IP_NF_NAT_H323
 	tristate
 	depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n
diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
index 56733c370327..ef33ff2cdda9 100644
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -54,6 +54,10 @@ obj-$(CONFIG_NF_NAT_AMANDA) += nf_nat_amanda.o
 obj-$(CONFIG_NF_NAT_FTP) += nf_nat_ftp.o
 obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o
 obj-$(CONFIG_NF_NAT_IRC) += nf_nat_irc.o
+obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o
+
+# NAT protocols (nf_nat)
+obj-$(CONFIG_NF_NAT_PROTO_GRE) += nf_nat_proto_gre.o
 
 # generic IP tables 
 obj-$(CONFIG_IP_NF_IPTABLES) += ip_tables.o
diff --git a/net/ipv4/netfilter/nf_nat_pptp.c b/net/ipv4/netfilter/nf_nat_pptp.c
new file mode 100644
index 000000000000..0ae45b79a4eb
--- /dev/null
+++ b/net/ipv4/netfilter/nf_nat_pptp.c
@@ -0,0 +1,315 @@
+/*
+ * nf_nat_pptp.c
+ *
+ * NAT support for PPTP (Point to Point Tunneling Protocol).
+ * PPTP is a a protocol for creating virtual private networks.
+ * It is a specification defined by Microsoft and some vendors
+ * working with Microsoft.  PPTP is built on top of a modified
+ * version of the Internet Generic Routing Encapsulation Protocol.
+ * GRE is defined in RFC 1701 and RFC 1702.  Documentation of
+ * PPTP can be found in RFC 2637
+ *
+ * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
+ *
+ * Development of this code funded by Astaro AG (http://www.astaro.com/)
+ *
+ * TODO: - NAT to a unique tuple, not to TCP source port
+ * 	   (needs netfilter tuple reservation)
+ */
+
+#include <linux/module.h>
+#include <linux/tcp.h>
+
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_helper.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <linux/netfilter/nf_conntrack_proto_gre.h>
+#include <linux/netfilter/nf_conntrack_pptp.h>
+
+#define NF_NAT_PPTP_VERSION "3.0"
+
+#define REQ_CID(req, off)		(*(__be16 *)((char *)(req) + (off)))
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
+MODULE_DESCRIPTION("Netfilter NAT helper module for PPTP");
+MODULE_ALIAS("ip_nat_pptp");
+
+#if 0
+extern const char *pptp_msg_name[];
+#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, \
+				       __FUNCTION__, ## args)
+#else
+#define DEBUGP(format, args...)
+#endif
+
+static void pptp_nat_expected(struct nf_conn *ct,
+			      struct nf_conntrack_expect *exp)
+{
+	struct nf_conn *master = ct->master;
+	struct nf_conntrack_expect *other_exp;
+	struct nf_conntrack_tuple t;
+	struct nf_ct_pptp_master *ct_pptp_info;
+	struct nf_nat_pptp *nat_pptp_info;
+	struct ip_nat_range range;
+
+	ct_pptp_info = &nfct_help(master)->help.ct_pptp_info;
+	nat_pptp_info = &nfct_nat(master)->help.nat_pptp_info;
+
+	/* And here goes the grand finale of corrosion... */
+	if (exp->dir == IP_CT_DIR_ORIGINAL) {
+		DEBUGP("we are PNS->PAC\n");
+		/* therefore, build tuple for PAC->PNS */
+		t.src.l3num = AF_INET;
+		t.src.u3.ip = master->tuplehash[!exp->dir].tuple.src.u3.ip;
+		t.src.u.gre.key = ct_pptp_info->pac_call_id;
+		t.dst.u3.ip = master->tuplehash[!exp->dir].tuple.dst.u3.ip;
+		t.dst.u.gre.key = ct_pptp_info->pns_call_id;
+		t.dst.protonum = IPPROTO_GRE;
+	} else {
+		DEBUGP("we are PAC->PNS\n");
+		/* build tuple for PNS->PAC */
+		t.src.l3num = AF_INET;
+		t.src.u3.ip = master->tuplehash[exp->dir].tuple.src.u3.ip;
+		t.src.u.gre.key = nat_pptp_info->pns_call_id;
+		t.dst.u3.ip = master->tuplehash[exp->dir].tuple.dst.u3.ip;
+		t.dst.u.gre.key = nat_pptp_info->pac_call_id;
+		t.dst.protonum = IPPROTO_GRE;
+	}
+
+	DEBUGP("trying to unexpect other dir: ");
+	NF_CT_DUMP_TUPLE(&t);
+	other_exp = nf_conntrack_expect_find_get(&t);
+	if (other_exp) {
+		nf_conntrack_unexpect_related(other_exp);
+		nf_conntrack_expect_put(other_exp);
+		DEBUGP("success\n");
+	} else {
+		DEBUGP("not found!\n");
+	}
+
+	/* This must be a fresh one. */
+	BUG_ON(ct->status & IPS_NAT_DONE_MASK);
+
+	/* Change src to where master sends to */
+	range.flags = IP_NAT_RANGE_MAP_IPS;
+	range.min_ip = range.max_ip
+		= ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
+	if (exp->dir == IP_CT_DIR_ORIGINAL) {
+		range.flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
+		range.min = range.max = exp->saved_proto;
+	}
+	/* hook doesn't matter, but it has to do source manip */
+	nf_nat_setup_info(ct, &range, NF_IP_POST_ROUTING);
+
+	/* For DST manip, map port here to where it's expected. */
+	range.flags = IP_NAT_RANGE_MAP_IPS;
+	range.min_ip = range.max_ip
+		= ct->master->tuplehash[!exp->dir].tuple.src.u3.ip;
+	if (exp->dir == IP_CT_DIR_REPLY) {
+		range.flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
+		range.min = range.max = exp->saved_proto;
+	}
+	/* hook doesn't matter, but it has to do destination manip */
+	nf_nat_setup_info(ct, &range, NF_IP_PRE_ROUTING);
+}
+
+/* outbound packets == from PNS to PAC */
+static int
+pptp_outbound_pkt(struct sk_buff **pskb,
+		  struct nf_conn *ct,
+		  enum ip_conntrack_info ctinfo,
+		  struct PptpControlHeader *ctlh,
+		  union pptp_ctrl_union *pptpReq)
+
+{
+	struct nf_ct_pptp_master *ct_pptp_info;
+	struct nf_nat_pptp *nat_pptp_info;
+	u_int16_t msg;
+	__be16 new_callid;
+	unsigned int cid_off;
+
+	ct_pptp_info  = &nfct_help(ct)->help.ct_pptp_info;
+	nat_pptp_info = &nfct_nat(ct)->help.nat_pptp_info;
+
+	new_callid = ct_pptp_info->pns_call_id;
+
+	switch (msg = ntohs(ctlh->messageType)) {
+	case PPTP_OUT_CALL_REQUEST:
+		cid_off = offsetof(union pptp_ctrl_union, ocreq.callID);
+		/* FIXME: ideally we would want to reserve a call ID
+		 * here.  current netfilter NAT core is not able to do
+		 * this :( For now we use TCP source port. This breaks
+		 * multiple calls within one control session */
+
+		/* save original call ID in nat_info */
+		nat_pptp_info->pns_call_id = ct_pptp_info->pns_call_id;
+
+		/* don't use tcph->source since we are at a DSTmanip
+		 * hook (e.g. PREROUTING) and pkt is not mangled yet */
+		new_callid = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.tcp.port;
+
+		/* save new call ID in ct info */
+		ct_pptp_info->pns_call_id = new_callid;
+		break;
+	case PPTP_IN_CALL_REPLY:
+		cid_off = offsetof(union pptp_ctrl_union, icack.callID);
+		break;
+	case PPTP_CALL_CLEAR_REQUEST:
+		cid_off = offsetof(union pptp_ctrl_union, clrreq.callID);
+		break;
+	default:
+		DEBUGP("unknown outbound packet 0x%04x:%s\n", msg,
+		      (msg <= PPTP_MSG_MAX)?
+		      pptp_msg_name[msg]:pptp_msg_name[0]);
+		/* fall through */
+	case PPTP_SET_LINK_INFO:
+		/* only need to NAT in case PAC is behind NAT box */
+	case PPTP_START_SESSION_REQUEST:
+	case PPTP_START_SESSION_REPLY:
+	case PPTP_STOP_SESSION_REQUEST:
+	case PPTP_STOP_SESSION_REPLY:
+	case PPTP_ECHO_REQUEST:
+	case PPTP_ECHO_REPLY:
+		/* no need to alter packet */
+		return NF_ACCEPT;
+	}
+
+	/* only OUT_CALL_REQUEST, IN_CALL_REPLY, CALL_CLEAR_REQUEST pass
+	 * down to here */
+	DEBUGP("altering call id from 0x%04x to 0x%04x\n",
+		ntohs(REQ_CID(pptpReq, cid_off)), ntohs(new_callid));
+
+	/* mangle packet */
+	if (nf_nat_mangle_tcp_packet(pskb, ct, ctinfo,
+	                             cid_off + sizeof(struct pptp_pkt_hdr) +
+	                             sizeof(struct PptpControlHeader),
+	                             sizeof(new_callid), (char *)&new_callid,
+	                             sizeof(new_callid)) == 0)
+		return NF_DROP;
+	return NF_ACCEPT;
+}
+
+static void
+pptp_exp_gre(struct nf_conntrack_expect *expect_orig,
+	     struct nf_conntrack_expect *expect_reply)
+{
+	struct nf_conn *ct = expect_orig->master;
+	struct nf_ct_pptp_master *ct_pptp_info;
+	struct nf_nat_pptp *nat_pptp_info;
+
+	ct_pptp_info  = &nfct_help(ct)->help.ct_pptp_info;
+	nat_pptp_info = &nfct_nat(ct)->help.nat_pptp_info;
+
+	/* save original PAC call ID in nat_info */
+	nat_pptp_info->pac_call_id = ct_pptp_info->pac_call_id;
+
+	/* alter expectation for PNS->PAC direction */
+	expect_orig->saved_proto.gre.key = ct_pptp_info->pns_call_id;
+	expect_orig->tuple.src.u.gre.key = nat_pptp_info->pns_call_id;
+	expect_orig->tuple.dst.u.gre.key = ct_pptp_info->pac_call_id;
+	expect_orig->dir = IP_CT_DIR_ORIGINAL;
+
+	/* alter expectation for PAC->PNS direction */
+	expect_reply->saved_proto.gre.key = nat_pptp_info->pns_call_id;
+	expect_reply->tuple.src.u.gre.key = nat_pptp_info->pac_call_id;
+	expect_reply->tuple.dst.u.gre.key = ct_pptp_info->pns_call_id;
+	expect_reply->dir = IP_CT_DIR_REPLY;
+}
+
+/* inbound packets == from PAC to PNS */
+static int
+pptp_inbound_pkt(struct sk_buff **pskb,
+		 struct nf_conn *ct,
+		 enum ip_conntrack_info ctinfo,
+		 struct PptpControlHeader *ctlh,
+		 union pptp_ctrl_union *pptpReq)
+{
+	struct nf_nat_pptp *nat_pptp_info;
+	u_int16_t msg;
+	__be16 new_pcid;
+	unsigned int pcid_off;
+
+	nat_pptp_info = &nfct_nat(ct)->help.nat_pptp_info;
+	new_pcid = nat_pptp_info->pns_call_id;
+
+	switch (msg = ntohs(ctlh->messageType)) {
+	case PPTP_OUT_CALL_REPLY:
+		pcid_off = offsetof(union pptp_ctrl_union, ocack.peersCallID);
+		break;
+	case PPTP_IN_CALL_CONNECT:
+		pcid_off = offsetof(union pptp_ctrl_union, iccon.peersCallID);
+		break;
+	case PPTP_IN_CALL_REQUEST:
+		/* only need to nat in case PAC is behind NAT box */
+		return NF_ACCEPT;
+	case PPTP_WAN_ERROR_NOTIFY:
+		pcid_off = offsetof(union pptp_ctrl_union, wanerr.peersCallID);
+		break;
+	case PPTP_CALL_DISCONNECT_NOTIFY:
+		pcid_off = offsetof(union pptp_ctrl_union, disc.callID);
+		break;
+	case PPTP_SET_LINK_INFO:
+		pcid_off = offsetof(union pptp_ctrl_union, setlink.peersCallID);
+		break;
+	default:
+		DEBUGP("unknown inbound packet %s\n", (msg <= PPTP_MSG_MAX)?
+			pptp_msg_name[msg]:pptp_msg_name[0]);
+		/* fall through */
+	case PPTP_START_SESSION_REQUEST:
+	case PPTP_START_SESSION_REPLY:
+	case PPTP_STOP_SESSION_REQUEST:
+	case PPTP_STOP_SESSION_REPLY:
+	case PPTP_ECHO_REQUEST:
+	case PPTP_ECHO_REPLY:
+		/* no need to alter packet */
+		return NF_ACCEPT;
+	}
+
+	/* only OUT_CALL_REPLY, IN_CALL_CONNECT, IN_CALL_REQUEST,
+	 * WAN_ERROR_NOTIFY, CALL_DISCONNECT_NOTIFY pass down here */
+
+	/* mangle packet */
+	DEBUGP("altering peer call id from 0x%04x to 0x%04x\n",
+		ntohs(REQ_CID(pptpReq, pcid_off)), ntohs(new_pcid));
+
+	if (nf_nat_mangle_tcp_packet(pskb, ct, ctinfo,
+	                             pcid_off + sizeof(struct pptp_pkt_hdr) +
+				     sizeof(struct PptpControlHeader),
+				     sizeof(new_pcid), (char *)&new_pcid,
+				     sizeof(new_pcid)) == 0)
+		return NF_DROP;
+	return NF_ACCEPT;
+}
+
+static int __init nf_nat_helper_pptp_init(void)
+{
+	nf_nat_need_gre();
+
+	BUG_ON(rcu_dereference(nf_nat_pptp_hook_outbound));
+	rcu_assign_pointer(nf_nat_pptp_hook_outbound, pptp_outbound_pkt);
+
+	BUG_ON(rcu_dereference(nf_nat_pptp_hook_inbound));
+	rcu_assign_pointer(nf_nat_pptp_hook_inbound, pptp_inbound_pkt);
+
+	BUG_ON(rcu_dereference(nf_nat_pptp_hook_exp_gre));
+	rcu_assign_pointer(nf_nat_pptp_hook_exp_gre, pptp_exp_gre);
+
+	BUG_ON(rcu_dereference(nf_nat_pptp_hook_expectfn));
+	rcu_assign_pointer(nf_nat_pptp_hook_expectfn, pptp_nat_expected);
+	return 0;
+}
+
+static void __exit nf_nat_helper_pptp_fini(void)
+{
+	rcu_assign_pointer(nf_nat_pptp_hook_expectfn, NULL);
+	rcu_assign_pointer(nf_nat_pptp_hook_exp_gre, NULL);
+	rcu_assign_pointer(nf_nat_pptp_hook_inbound, NULL);
+	rcu_assign_pointer(nf_nat_pptp_hook_outbound, NULL);
+	synchronize_rcu();
+}
+
+module_init(nf_nat_helper_pptp_init);
+module_exit(nf_nat_helper_pptp_fini);
diff --git a/net/ipv4/netfilter/nf_nat_proto_gre.c b/net/ipv4/netfilter/nf_nat_proto_gre.c
new file mode 100644
index 000000000000..d3de579e09d2
--- /dev/null
+++ b/net/ipv4/netfilter/nf_nat_proto_gre.c
@@ -0,0 +1,179 @@
+/*
+ * nf_nat_proto_gre.c
+ *
+ * NAT protocol helper module for GRE.
+ *
+ * GRE is a generic encapsulation protocol, which is generally not very
+ * suited for NAT, as it has no protocol-specific part as port numbers.
+ *
+ * It has an optional key field, which may help us distinguishing two
+ * connections between the same two hosts.
+ *
+ * GRE is defined in RFC 1701 and RFC 1702, as well as RFC 2784
+ *
+ * PPTP is built on top of a modified version of GRE, and has a mandatory
+ * field called "CallID", which serves us for the same purpose as the key
+ * field in plain GRE.
+ *
+ * Documentation about PPTP can be found in RFC 2637
+ *
+ * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
+ *
+ * Development of this code funded by Astaro AG (http://www.astaro.com/)
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_nat_protocol.h>
+#include <linux/netfilter/nf_conntrack_proto_gre.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
+MODULE_DESCRIPTION("Netfilter NAT protocol helper module for GRE");
+
+#if 0
+#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, \
+				       __FUNCTION__, ## args)
+#else
+#define DEBUGP(x, args...)
+#endif
+
+/* is key in given range between min and max */
+static int
+gre_in_range(const struct nf_conntrack_tuple *tuple,
+	     enum nf_nat_manip_type maniptype,
+	     const union nf_conntrack_man_proto *min,
+	     const union nf_conntrack_man_proto *max)
+{
+	__be16 key;
+
+	if (maniptype == IP_NAT_MANIP_SRC)
+		key = tuple->src.u.gre.key;
+	else
+		key = tuple->dst.u.gre.key;
+
+	return ntohs(key) >= ntohs(min->gre.key) &&
+	       ntohs(key) <= ntohs(max->gre.key);
+}
+
+/* generate unique tuple ... */
+static int
+gre_unique_tuple(struct nf_conntrack_tuple *tuple,
+		 const struct nf_nat_range *range,
+		 enum nf_nat_manip_type maniptype,
+		 const struct nf_conn *conntrack)
+{
+	static u_int16_t key;
+	__be16 *keyptr;
+	unsigned int min, i, range_size;
+
+	if (maniptype == IP_NAT_MANIP_SRC)
+		keyptr = &tuple->src.u.gre.key;
+	else
+		keyptr = &tuple->dst.u.gre.key;
+
+	if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) {
+		DEBUGP("%p: NATing GRE PPTP\n", conntrack);
+		min = 1;
+		range_size = 0xffff;
+	} else {
+		min = ntohs(range->min.gre.key);
+		range_size = ntohs(range->max.gre.key) - min + 1;
+	}
+
+	DEBUGP("min = %u, range_size = %u\n", min, range_size);
+
+	for (i = 0; i < range_size; i++, key++) {
+		*keyptr = htons(min + key % range_size);
+		if (!nf_nat_used_tuple(tuple, conntrack))
+			return 1;
+	}
+
+	DEBUGP("%p: no NAT mapping\n", conntrack);
+	return 0;
+}
+
+/* manipulate a GRE packet according to maniptype */
+static int
+gre_manip_pkt(struct sk_buff **pskb, unsigned int iphdroff,
+	      const struct nf_conntrack_tuple *tuple,
+	      enum nf_nat_manip_type maniptype)
+{
+	struct gre_hdr *greh;
+	struct gre_hdr_pptp *pgreh;
+	struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff);
+	unsigned int hdroff = iphdroff + iph->ihl * 4;
+
+	/* pgreh includes two optional 32bit fields which are not required
+	 * to be there.  That's where the magic '8' comes from */
+	if (!skb_make_writable(pskb, hdroff + sizeof(*pgreh) - 8))
+		return 0;
+
+	greh = (void *)(*pskb)->data + hdroff;
+	pgreh = (struct gre_hdr_pptp *)greh;
+
+	/* we only have destination manip of a packet, since 'source key'
+	 * is not present in the packet itself */
+	if (maniptype != IP_NAT_MANIP_DST)
+		return 1;
+	switch (greh->version) {
+	case 0:
+		if (!greh->key) {
+			DEBUGP("can't nat GRE w/o key\n");
+			break;
+		}
+		if (greh->csum) {
+			/* FIXME: Never tested this code... */
+			nf_proto_csum_replace4(gre_csum(greh), *pskb,
+					       *(gre_key(greh)),
+					       tuple->dst.u.gre.key, 0);
+		}
+		*(gre_key(greh)) = tuple->dst.u.gre.key;
+		break;