[deliverable/linux.git] / net / ipv4 / netfilter / ip_nat_helper_pptp.c

/*
 * ip_nat_pptp.c	- Version 3.0
 *
 * 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)
 *
 * Changes:
 *     2002-02-10 - Version 1.3
 *       - Use ip_nat_mangle_tcp_packet() because of cloned skb's
 *	   in local connections (Philip Craig <philipc@snapgear.com>)
 *       - add checks for magicCookie and pptp version
 *       - make argument list of pptp_{out,in}bound_packet() shorter
 *       - move to C99 style initializers
 *       - print version number at module loadtime
 *     2003-09-22 - Version 1.5
 *       - use SNATed tcp sourceport as callid, since we get called before
 *	   TCP header is mangled (Philip Craig <philipc@snapgear.com>)
 *     2004-10-22 - Version 2.0
 *       - kernel 2.6.x version
 *     2005-06-10 - Version 3.0
 *       - kernel >= 2.6.11 version,
 *	   funded by Oxcoda NetBox Blue (http://www.netboxblue.com/)
 *
 */

#include <linux/module.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <net/tcp.h>

#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/ip_nat_helper.h>
#include <linux/netfilter_ipv4/ip_nat_pptp.h>
#include <linux/netfilter_ipv4/ip_conntrack_core.h>
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
#include <linux/netfilter_ipv4/ip_conntrack_proto_gre.h>
#include <linux/netfilter_ipv4/ip_conntrack_pptp.h>

#define IP_NAT_PPTP_VERSION "3.0"

#define REQ_CID(req, off)		(*(u_int16_t *)((char *)(req) + (off)))

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
MODULE_DESCRIPTION("Netfilter NAT helper module for 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 ip_conntrack *ct,
			      struct ip_conntrack_expect *exp)
{
	struct ip_conntrack *master = ct->master;
	struct ip_conntrack_expect *other_exp;
	struct ip_conntrack_tuple t;
	struct ip_ct_pptp_master *ct_pptp_info;
	struct ip_nat_pptp *nat_pptp_info;
	struct ip_nat_range range;

	ct_pptp_info = &master->help.ct_pptp_info;
	nat_pptp_info = &master->nat.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.ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip;
		t.src.u.gre.key = master->help.ct_pptp_info.pac_call_id;
		t.dst.ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip;
		t.dst.u.gre.key = master->help.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.ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip;
		t.src.u.gre.key = master->nat.help.nat_pptp_info.pns_call_id;
		t.dst.ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip;
		t.dst.u.gre.key = master->nat.help.nat_pptp_info.pac_call_id;
		t.dst.protonum = IPPROTO_GRE;
	}

	DEBUGP("trying to unexpect other dir: ");
	DUMP_TUPLE(&t);
	other_exp = ip_conntrack_expect_find(&t);
	if (other_exp) {
		ip_conntrack_unexpect_related(other_exp);
		ip_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.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 */
	ip_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.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 */
	ip_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 ip_conntrack *ct,
		  enum ip_conntrack_info ctinfo,
		  struct PptpControlHeader *ctlh,
		  union pptp_ctrl_union *pptpReq)

{
	struct ip_ct_pptp_master *ct_pptp_info = &ct->help.ct_pptp_info;
	struct ip_nat_pptp *nat_pptp_info = &ct->nat.help.nat_pptp_info;
	u_int16_t msg;
	__be16 new_callid;
	unsigned int cid_off;

	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, icreq.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 (ip_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 int
pptp_exp_gre(struct ip_conntrack_expect *expect_orig,
	     struct ip_conntrack_expect *expect_reply)
{
	struct ip_ct_pptp_master *ct_pptp_info =
				&expect_orig->master->help.ct_pptp_info;
	struct ip_nat_pptp *nat_pptp_info =
				&expect_orig->master->nat.help.nat_pptp_info;

	struct ip_conntrack *ct = expect_orig->master;

	struct ip_conntrack_tuple inv_t;
	struct ip_conntrack_tuple *orig_t, *reply_t;

	/* save original PAC call ID in nat_info */
	nat_pptp_info->pac_call_id = ct_pptp_info->pac_call_id;

	/* alter expectation */
	orig_t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
	reply_t = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;

	/* alter expectation for PNS->PAC direction */
	invert_tuplepr(&inv_t, &expect_orig->tuple);
	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;
	inv_t.src.ip = reply_t->src.ip;
	inv_t.dst.ip = reply_t->dst.ip;
	inv_t.src.u.gre.key = nat_pptp_info->pac_call_id;
	inv_t.dst.u.gre.key = ct_pptp_info->pns_call_id;

	if (!ip_conntrack_expect_related(expect_orig)) {
		DEBUGP("successfully registered expect\n");
	} else {
		DEBUGP("can't expect_related(expect_orig)\n");
		return 1;
	}

	/* alter expectation for PAC->PNS direction */
	invert_tuplepr(&inv_t, &expect_reply->tuple);
	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;
	inv_t.src.ip = orig_t->src.ip;
	inv_t.dst.ip = orig_t->dst.ip;
	inv_t.src.u.gre.key = nat_pptp_info->pns_call_id;
	inv_t.dst.u.gre.key = ct_pptp_info->pac_call_id;

	if (!ip_conntrack_expect_related(expect_reply)) {
		DEBUGP("successfully registered expect\n");
	} else {
		DEBUGP("can't expect_related(expect_reply)\n");
		ip_conntrack_unexpect_related(expect_orig);
		return 1;
	}

	if (ip_ct_gre_keymap_add(ct, &expect_reply->tuple, 0) < 0) {
		DEBUGP("can't register original keymap\n");
		ip_conntrack_unexpect_related(expect_orig);
		ip_conntrack_unexpect_related(expect_reply);
		return 1;
	}

	if (ip_ct_gre_keymap_add(ct, &inv_t, 1) < 0) {
		DEBUGP("can't register reply keymap\n");
		ip_conntrack_unexpect_related(expect_orig);
		ip_conntrack_unexpect_related(expect_reply);
		ip_ct_gre_keymap_destroy(ct);
		return 1;
	}

	return 0;
}

/* inbound packets == from PAC to PNS */
static int
pptp_inbound_pkt(struct sk_buff **pskb,
		 struct ip_conntrack *ct,
		 enum ip_conntrack_info ctinfo,
		 struct PptpControlHeader *ctlh,
		 union pptp_ctrl_union *pptpReq)
{
	struct ip_nat_pptp *nat_pptp_info = &ct->nat.help.nat_pptp_info;
	u_int16_t msg;
	__be16 new_pcid;
	unsigned int pcid_off;

	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 (ip_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;
}


extern int __init ip_nat_proto_gre_init(void);
extern void __exit ip_nat_proto_gre_fini(void);

static int __init ip_nat_helper_pptp_init(void)
{
	int ret;

	DEBUGP("%s: registering NAT helper\n", __FILE__);

	ret = ip_nat_proto_gre_init();
	if (ret < 0)
		return ret;

	BUG_ON(ip_nat_pptp_hook_outbound);
	ip_nat_pptp_hook_outbound = &pptp_outbound_pkt;

	BUG_ON(ip_nat_pptp_hook_inbound);
	ip_nat_pptp_hook_inbound = &pptp_inbound_pkt;

	BUG_ON(ip_nat_pptp_hook_exp_gre);
	ip_nat_pptp_hook_exp_gre = &pptp_exp_gre;

	BUG_ON(ip_nat_pptp_hook_expectfn);
	ip_nat_pptp_hook_expectfn = &pptp_nat_expected;

	printk("ip_nat_pptp version %s loaded\n", IP_NAT_PPTP_VERSION);
	return 0;
}

static void __exit ip_nat_helper_pptp_fini(void)
{
	DEBUGP("cleanup_module\n" );

	ip_nat_pptp_hook_expectfn = NULL;
	ip_nat_pptp_hook_exp_gre = NULL;
	ip_nat_pptp_hook_inbound = NULL;
	ip_nat_pptp_hook_outbound = NULL;

	ip_nat_proto_gre_fini();
	/* Make sure noone calls it, meanwhile */
	synchronize_net();

	printk("ip_nat_pptp version %s unloaded\n", IP_NAT_PPTP_VERSION);
}

module_init(ip_nat_helper_pptp_init);
module_exit(ip_nat_helper_pptp_fini);
Commit	Line	Data
926b50f9 HW	1	/*
	2	* ip_nat_pptp.c - Version 3.0
	3	*
	4	* NAT support for PPTP (Point to Point Tunneling Protocol).
	5	* PPTP is a a protocol for creating virtual private networks.
	6	* It is a specification defined by Microsoft and some vendors
	7	* working with Microsoft. PPTP is built on top of a modified
	8	* version of the Internet Generic Routing Encapsulation Protocol.
	9	* GRE is defined in RFC 1701 and RFC 1702. Documentation of
	10	* PPTP can be found in RFC 2637
	11	*
	12	* (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
	13	*
	14	* Development of this code funded by Astaro AG (http://www.astaro.com/)
	15	*
	16	* TODO: - NAT to a unique tuple, not to TCP source port
	17	* (needs netfilter tuple reservation)
	18	*
	19	* Changes:
	20	* 2002-02-10 - Version 1.3
	21	* - Use ip_nat_mangle_tcp_packet() because of cloned skb's
	22	* in local connections (Philip Craig <philipc@snapgear.com>)
	23	* - add checks for magicCookie and pptp version
	24	* - make argument list of pptp_{out,in}bound_packet() shorter
	25	* - move to C99 style initializers
	26	* - print version number at module loadtime
	27	* 2003-09-22 - Version 1.5
	28	* - use SNATed tcp sourceport as callid, since we get called before
	29	* TCP header is mangled (Philip Craig <philipc@snapgear.com>)
	30	* 2004-10-22 - Version 2.0
	31	* - kernel 2.6.x version
	32	* 2005-06-10 - Version 3.0
	33	* - kernel >= 2.6.11 version,
	34	* funded by Oxcoda NetBox Blue (http://www.netboxblue.com/)
edd5a329	35	*
926b50f9 HW	36	*/
926b50f9 HW	37
926b50f9 HW	38	#include <linux/module.h>
	39	#include <linux/ip.h>
	40	#include <linux/tcp.h>
	41	#include <net/tcp.h>
	42
	43	#include <linux/netfilter_ipv4/ip_nat.h>
	44	#include <linux/netfilter_ipv4/ip_nat_rule.h>
	45	#include <linux/netfilter_ipv4/ip_nat_helper.h>
	46	#include <linux/netfilter_ipv4/ip_nat_pptp.h>
	47	#include <linux/netfilter_ipv4/ip_conntrack_core.h>
	48	#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
	49	#include <linux/netfilter_ipv4/ip_conntrack_proto_gre.h>
	50	#include <linux/netfilter_ipv4/ip_conntrack_pptp.h>
	51
	52	#define IP_NAT_PPTP_VERSION "3.0"
	53
f2ad52c9 HE	54	#define REQ_CID(req, off) ((u_int16_t )((char *)(req) + (off)))
f2ad52c9 HE	55
926b50f9 HW	56	MODULE_LICENSE("GPL");
	57	MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
	58	MODULE_DESCRIPTION("Netfilter NAT helper module for PPTP");
	59
	60
	61	#if 0
	62	extern const char *pptp_msg_name[];
	63	#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, \
	64	__FUNCTION__, ## args)
	65	#else
	66	#define DEBUGP(format, args...)
	67	#endif
	68
	69	static void pptp_nat_expected(struct ip_conntrack *ct,
	70	struct ip_conntrack_expect *exp)
	71	{
	72	struct ip_conntrack *master = ct->master;
	73	struct ip_conntrack_expect *other_exp;
	74	struct ip_conntrack_tuple t;
	75	struct ip_ct_pptp_master *ct_pptp_info;
	76	struct ip_nat_pptp *nat_pptp_info;
5978a9b8	77	struct ip_nat_range range;
926b50f9 HW	78
	79	ct_pptp_info = &master->help.ct_pptp_info;
	80	nat_pptp_info = &master->nat.help.nat_pptp_info;
	81
	82	/* And here goes the grand finale of corrosion... */
	83
	84	if (exp->dir == IP_CT_DIR_ORIGINAL) {
	85	DEBUGP("we are PNS->PAC\n");
	86	/* therefore, build tuple for PAC->PNS */
	87	t.src.ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip;
955b9442	88	t.src.u.gre.key = master->help.ct_pptp_info.pac_call_id;
926b50f9	89	t.dst.ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip;
955b9442	90	t.dst.u.gre.key = master->help.ct_pptp_info.pns_call_id;
926b50f9 HW	91	t.dst.protonum = IPPROTO_GRE;
	92	} else {
	93	DEBUGP("we are PAC->PNS\n");
	94	/* build tuple for PNS->PAC */
	95	t.src.ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip;
955b9442	96	t.src.u.gre.key = master->nat.help.nat_pptp_info.pns_call_id;
926b50f9	97	t.dst.ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip;
955b9442	98	t.dst.u.gre.key = master->nat.help.nat_pptp_info.pac_call_id;
926b50f9 HW	99	t.dst.protonum = IPPROTO_GRE;
	100	}
	101
	102	DEBUGP("trying to unexpect other dir: ");
	103	DUMP_TUPLE(&t);
	104	other_exp = ip_conntrack_expect_find(&t);
	105	if (other_exp) {
	106	ip_conntrack_unexpect_related(other_exp);
	107	ip_conntrack_expect_put(other_exp);
	108	DEBUGP("success\n");
	109	} else {
	110	DEBUGP("not found!\n");
	111	}
	112
5978a9b8 PC	113	/* This must be a fresh one. */
	114	BUG_ON(ct->status & IPS_NAT_DONE_MASK);
	115
	116	/* Change src to where master sends to */
	117	range.flags = IP_NAT_RANGE_MAP_IPS;
	118	range.min_ip = range.max_ip
	119	= ct->master->tuplehash[!exp->dir].tuple.dst.ip;
	120	if (exp->dir == IP_CT_DIR_ORIGINAL) {
	121	range.flags \|= IP_NAT_RANGE_PROTO_SPECIFIED;
	122	range.min = range.max = exp->saved_proto;
	123	}
	124	/* hook doesn't matter, but it has to do source manip */
	125	ip_nat_setup_info(ct, &range, NF_IP_POST_ROUTING);
	126
	127	/* For DST manip, map port here to where it's expected. */
	128	range.flags = IP_NAT_RANGE_MAP_IPS;
	129	range.min_ip = range.max_ip
	130	= ct->master->tuplehash[!exp->dir].tuple.src.ip;
	131	if (exp->dir == IP_CT_DIR_REPLY) {
	132	range.flags \|= IP_NAT_RANGE_PROTO_SPECIFIED;
	133	range.min = range.max = exp->saved_proto;
	134	}
	135	/* hook doesn't matter, but it has to do destination manip */
	136	ip_nat_setup_info(ct, &range, NF_IP_PRE_ROUTING);
926b50f9 HW	137	}
	138
	139	/* outbound packets == from PNS to PAC */
	140	static int
	141	pptp_outbound_pkt(struct sk_buff **pskb,
	142	struct ip_conntrack *ct,
	143	enum ip_conntrack_info ctinfo,
	144	struct PptpControlHeader *ctlh,
	145	union pptp_ctrl_union *pptpReq)
	146
	147	{
	148	struct ip_ct_pptp_master *ct_pptp_info = &ct->help.ct_pptp_info;
	149	struct ip_nat_pptp *nat_pptp_info = &ct->nat.help.nat_pptp_info;
955b9442 PM	150	u_int16_t msg;
955b9442 PM	151	__be16 new_callid;
03b9feca	152	unsigned int cid_off;
926b50f9	153
955b9442	154	new_callid = ct_pptp_info->pns_call_id;
edd5a329	155
926b50f9	156	switch (msg = ntohs(ctlh->messageType)) {
edd5a329 PM	157	case PPTP_OUT_CALL_REQUEST:
	158	cid_off = offsetof(union pptp_ctrl_union, ocreq.callID);
	159	/* FIXME: ideally we would want to reserve a call ID
	160	* here. current netfilter NAT core is not able to do
	161	* this :( For now we use TCP source port. This breaks
	162	* multiple calls within one control session */
	163
	164	/* save original call ID in nat_info */
	165	nat_pptp_info->pns_call_id = ct_pptp_info->pns_call_id;
	166
	167	/* don't use tcph->source since we are at a DSTmanip
	168	* hook (e.g. PREROUTING) and pkt is not mangled yet */
	169	new_callid = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.tcp.port;
	170
	171	/* save new call ID in ct info */
955b9442	172	ct_pptp_info->pns_call_id = new_callid;
edd5a329 PM	173	break;
	174	case PPTP_IN_CALL_REPLY:
	175	cid_off = offsetof(union pptp_ctrl_union, icreq.callID);
	176	break;
	177	case PPTP_CALL_CLEAR_REQUEST:
	178	cid_off = offsetof(union pptp_ctrl_union, clrreq.callID);
	179	break;
	180	default:
	181	DEBUGP("unknown outbound packet 0x%04x:%s\n", msg,
	182	(msg <= PPTP_MSG_MAX)?
	183	pptp_msg_name[msg]:pptp_msg_name[0]);
	184	/* fall through */
	185
	186	case PPTP_SET_LINK_INFO:
	187	/* only need to NAT in case PAC is behind NAT box */
	188	case PPTP_START_SESSION_REQUEST:
	189	case PPTP_START_SESSION_REPLY:
	190	case PPTP_STOP_SESSION_REQUEST:
	191	case PPTP_STOP_SESSION_REPLY:
	192	case PPTP_ECHO_REQUEST:
	193	case PPTP_ECHO_REPLY:
	194	/* no need to alter packet */
	195	return NF_ACCEPT;
926b50f9 HW	196	}
	197
	198	/* only OUT_CALL_REQUEST, IN_CALL_REPLY, CALL_CLEAR_REQUEST pass
	199	* down to here */
926b50f9	200	DEBUGP("altering call id from 0x%04x to 0x%04x\n",
f2ad52c9	201	ntohs(REQ_CID(pptpReq, cid_off)), ntohs(new_callid));
926b50f9 HW	202
	203	/* mangle packet */
	204	if (ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
03b9feca PM	205	cid_off + sizeof(struct pptp_pkt_hdr) +
	206	sizeof(struct PptpControlHeader),
	207	sizeof(new_callid), (char *)&new_callid,
	208	sizeof(new_callid)) == 0)
926b50f9 HW	209	return NF_DROP;
	210
	211	return NF_ACCEPT;
	212	}
	213
	214	static int
	215	pptp_exp_gre(struct ip_conntrack_expect *expect_orig,
	216	struct ip_conntrack_expect *expect_reply)
	217	{
edd5a329	218	struct ip_ct_pptp_master *ct_pptp_info =
926b50f9	219	&expect_orig->master->help.ct_pptp_info;
edd5a329	220	struct ip_nat_pptp *nat_pptp_info =
926b50f9 HW	221	&expect_orig->master->nat.help.nat_pptp_info;
	222
	223	struct ip_conntrack *ct = expect_orig->master;
	224
	225	struct ip_conntrack_tuple inv_t;
	226	struct ip_conntrack_tuple orig_t, reply_t;
	227
	228	/* save original PAC call ID in nat_info */
	229	nat_pptp_info->pac_call_id = ct_pptp_info->pac_call_id;
	230
	231	/* alter expectation */
	232	orig_t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
	233	reply_t = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
	234
	235	/* alter expectation for PNS->PAC direction */
	236	invert_tuplepr(&inv_t, &expect_orig->tuple);
955b9442 PM	237	expect_orig->saved_proto.gre.key = ct_pptp_info->pns_call_id;
	238	expect_orig->tuple.src.u.gre.key = nat_pptp_info->pns_call_id;
	239	expect_orig->tuple.dst.u.gre.key = ct_pptp_info->pac_call_id;
3428c209	240	expect_orig->dir = IP_CT_DIR_ORIGINAL;
926b50f9 HW	241	inv_t.src.ip = reply_t->src.ip;
926b50f9 HW	242	inv_t.dst.ip = reply_t->dst.ip;
955b9442 PM	243	inv_t.src.u.gre.key = nat_pptp_info->pac_call_id;
955b9442 PM	244	inv_t.dst.u.gre.key = ct_pptp_info->pns_call_id;
926b50f9 HW	245
	246	if (!ip_conntrack_expect_related(expect_orig)) {
	247	DEBUGP("successfully registered expect\n");
	248	} else {
	249	DEBUGP("can't expect_related(expect_orig)\n");
	250	return 1;
	251	}
	252
	253	/* alter expectation for PAC->PNS direction */
	254	invert_tuplepr(&inv_t, &expect_reply->tuple);
955b9442 PM	255	expect_reply->saved_proto.gre.key = nat_pptp_info->pns_call_id;
	256	expect_reply->tuple.src.u.gre.key = nat_pptp_info->pac_call_id;
	257	expect_reply->tuple.dst.u.gre.key = ct_pptp_info->pns_call_id;
3428c209	258	expect_reply->dir = IP_CT_DIR_REPLY;
926b50f9 HW	259	inv_t.src.ip = orig_t->src.ip;
926b50f9 HW	260	inv_t.dst.ip = orig_t->dst.ip;
955b9442 PM	261	inv_t.src.u.gre.key = nat_pptp_info->pns_call_id;
955b9442 PM	262	inv_t.dst.u.gre.key = ct_pptp_info->pac_call_id;
926b50f9 HW	263
	264	if (!ip_conntrack_expect_related(expect_reply)) {
	265	DEBUGP("successfully registered expect\n");
	266	} else {
	267	DEBUGP("can't expect_related(expect_reply)\n");
	268	ip_conntrack_unexpect_related(expect_orig);
	269	return 1;
	270	}
	271
	272	if (ip_ct_gre_keymap_add(ct, &expect_reply->tuple, 0) < 0) {
	273	DEBUGP("can't register original keymap\n");
	274	ip_conntrack_unexpect_related(expect_orig);
	275	ip_conntrack_unexpect_related(expect_reply);
	276	return 1;
	277	}
	278
	279	if (ip_ct_gre_keymap_add(ct, &inv_t, 1) < 0) {
	280	DEBUGP("can't register reply keymap\n");
	281	ip_conntrack_unexpect_related(expect_orig);
	282	ip_conntrack_unexpect_related(expect_reply);
	283	ip_ct_gre_keymap_destroy(ct);
	284	return 1;
	285	}
	286
	287	return 0;
	288	}
	289
	290	/* inbound packets == from PAC to PNS */
	291	static int
	292	pptp_inbound_pkt(struct sk_buff **pskb,
	293	struct ip_conntrack *ct,
	294	enum ip_conntrack_info ctinfo,
	295	struct PptpControlHeader *ctlh,
	296	union pptp_ctrl_union *pptpReq)
	297	{
	298	struct ip_nat_pptp *nat_pptp_info = &ct->nat.help.nat_pptp_info;
a1ad1dee	299	u_int16_t msg;
955b9442	300	__be16 new_pcid;
a1ad1dee	301	unsigned int pcid_off;
926b50f9	302
955b9442	303	new_pcid = nat_pptp_info->pns_call_id;
926b50f9 HW	304
	305	switch (msg = ntohs(ctlh->messageType)) {
	306	case PPTP_OUT_CALL_REPLY:
03b9feca	307	pcid_off = offsetof(union pptp_ctrl_union, ocack.peersCallID);
926b50f9 HW	308	break;
926b50f9 HW	309	case PPTP_IN_CALL_CONNECT:
03b9feca	310	pcid_off = offsetof(union pptp_ctrl_union, iccon.peersCallID);
926b50f9 HW	311	break;
	312	case PPTP_IN_CALL_REQUEST:
	313	/* only need to nat in case PAC is behind NAT box */
15db3470	314	return NF_ACCEPT;
926b50f9	315	case PPTP_WAN_ERROR_NOTIFY:
03b9feca	316	pcid_off = offsetof(union pptp_ctrl_union, wanerr.peersCallID);
926b50f9 HW	317	break;
926b50f9 HW	318	case PPTP_CALL_DISCONNECT_NOTIFY:
03b9feca	319	pcid_off = offsetof(union pptp_ctrl_union, disc.callID);
926b50f9 HW	320	break;
926b50f9 HW	321	case PPTP_SET_LINK_INFO:
03b9feca	322	pcid_off = offsetof(union pptp_ctrl_union, setlink.peersCallID);
926b50f9 HW	323	break;
	324
	325	default:
edd5a329	326	DEBUGP("unknown inbound packet %s\n", (msg <= PPTP_MSG_MAX)?
926b50f9 HW	327	pptp_msg_name[msg]:pptp_msg_name[0]);
	328	/* fall through */
	329
	330	case PPTP_START_SESSION_REQUEST:
	331	case PPTP_START_SESSION_REPLY:
	332	case PPTP_STOP_SESSION_REQUEST:
	333	case PPTP_STOP_SESSION_REPLY:
	334	case PPTP_ECHO_REQUEST:
	335	case PPTP_ECHO_REPLY:
	336	/* no need to alter packet */
	337	return NF_ACCEPT;
	338	}
	339
	340	/* only OUT_CALL_REPLY, IN_CALL_CONNECT, IN_CALL_REQUEST,
	341	* WAN_ERROR_NOTIFY, CALL_DISCONNECT_NOTIFY pass down here */
	342
	343	/* mangle packet */
926b50f9	344	DEBUGP("altering peer call id from 0x%04x to 0x%04x\n",
f2ad52c9	345	ntohs(REQ_CID(pptpReq, pcid_off)), ntohs(new_pcid));
c07bc1ff PM	346
	347	if (ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
	348	pcid_off + sizeof(struct pptp_pkt_hdr) +
	349	sizeof(struct PptpControlHeader),
	350	sizeof(new_pcid), (char *)&new_pcid,
	351	sizeof(new_pcid)) == 0)
	352	return NF_DROP;
926b50f9 HW	353	return NF_ACCEPT;
	354	}
	355
	356
	357	extern int __init ip_nat_proto_gre_init(void);
	358	extern void __exit ip_nat_proto_gre_fini(void);
	359
65b4b4e8	360	static int __init ip_nat_helper_pptp_init(void)
926b50f9 HW	361	{
	362	int ret;
	363
	364	DEBUGP("%s: registering NAT helper\n", __FILE__);
	365
	366	ret = ip_nat_proto_gre_init();
	367	if (ret < 0)
	368	return ret;
	369
	370	BUG_ON(ip_nat_pptp_hook_outbound);
	371	ip_nat_pptp_hook_outbound = &pptp_outbound_pkt;
	372
	373	BUG_ON(ip_nat_pptp_hook_inbound);
	374	ip_nat_pptp_hook_inbound = &pptp_inbound_pkt;
	375
	376	BUG_ON(ip_nat_pptp_hook_exp_gre);
	377	ip_nat_pptp_hook_exp_gre = &pptp_exp_gre;
	378
	379	BUG_ON(ip_nat_pptp_hook_expectfn);
	380	ip_nat_pptp_hook_expectfn = &pptp_nat_expected;
	381
	382	printk("ip_nat_pptp version %s loaded\n", IP_NAT_PPTP_VERSION);
	383	return 0;
	384	}
	385
65b4b4e8	386	static void __exit ip_nat_helper_pptp_fini(void)
926b50f9 HW	387	{
	388	DEBUGP("cleanup_module\n" );
	389
	390	ip_nat_pptp_hook_expectfn = NULL;
	391	ip_nat_pptp_hook_exp_gre = NULL;
	392	ip_nat_pptp_hook_inbound = NULL;
	393	ip_nat_pptp_hook_outbound = NULL;
	394
	395	ip_nat_proto_gre_fini();
	396	/* Make sure noone calls it, meanwhile */
	397	synchronize_net();
	398
	399	printk("ip_nat_pptp version %s unloaded\n", IP_NAT_PPTP_VERSION);
	400	}
	401
65b4b4e8 AM	402	module_init(ip_nat_helper_pptp_init);
65b4b4e8 AM	403	module_exit(ip_nat_helper_pptp_fini);