linux/net/ipv4/netfilter/nf_nat_pptp.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * nf_nat_pptp.c
 *
 * NAT support for PPTP (Point to Point Tunneling Protocol).
 * PPTP is 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 <[email protected]>
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 *
 * (C) 2006-2012 Patrick McHardy <[email protected]>
 *
 * 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_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <linux/netfilter/nf_conntrack_proto_gre.h>
#include <linux/netfilter/nf_conntrack_pptp.h>

#define NF_NAT_PPTP_VERSION …

#define REQ_CID(req, off) …

MODULE_LICENSE(…) …;
MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_ALIAS_NF_NAT_HELPER(…) …;

static void pptp_nat_expected(struct nf_conn *ct,
			      struct nf_conntrack_expect *exp)
{ … }

/* outbound packets == from PNS to PAC */
static int
pptp_outbound_pkt(struct sk_buff *skb,
		  struct nf_conn *ct,
		  enum ip_conntrack_info ctinfo,
		  unsigned int protoff,
		  struct PptpControlHeader *ctlh,
		  union pptp_ctrl_union *pptpReq)

{ … }

static void
pptp_exp_gre(struct nf_conntrack_expect *expect_orig,
	     struct nf_conntrack_expect *expect_reply)
{ … }

/* inbound packets == from PAC to PNS */
static int
pptp_inbound_pkt(struct sk_buff *skb,
		 struct nf_conn *ct,
		 enum ip_conntrack_info ctinfo,
		 unsigned int protoff,
		 struct PptpControlHeader *ctlh,
		 union pptp_ctrl_union *pptpReq)
{ … }

static const struct nf_nat_pptp_hook pptp_hooks = …;

static int __init nf_nat_helper_pptp_init(void)
{ … }

static void __exit nf_nat_helper_pptp_fini(void)
{ … }

module_init(…) …;
module_exit(nf_nat_helper_pptp_fini);