[linux-2.6-block.git] / net / ipv4 / netfilter / nf_nat_pptp.c

/*
 * 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/)
 *
 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
 *
 * 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 "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");

static void pptp_nat_expected(struct nf_conn *ct,
			      struct nf_conntrack_expect *exp)
{
	struct net *net = nf_ct_net(ct);
	const struct nf_conn *master = ct->master;
	struct nf_conntrack_expect *other_exp;
	struct nf_conntrack_tuple t = {};
	const struct nf_ct_pptp_master *ct_pptp_info;
	const struct nf_nat_pptp *nat_pptp_info;
	struct nf_nat_range range;

	ct_pptp_info = nfct_help_data(master);
	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) {
		pr_debug("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 {
		pr_debug("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;
	}

	pr_debug("trying to unexpect other dir: ");
	nf_ct_dump_tuple_ip(&t);
	other_exp = nf_ct_expect_find_get(net, nf_ct_zone(ct), &t);
	if (other_exp) {
		nf_ct_unexpect_related(other_exp);
		nf_ct_expect_put(other_exp);
		pr_debug("success\n");
	} else {
		pr_debug("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 = NF_NAT_RANGE_MAP_IPS;
	range.min_addr = range.max_addr
		= ct->master->tuplehash[!exp->dir].tuple.dst.u3;
	if (exp->dir == IP_CT_DIR_ORIGINAL) {
		range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
		range.min_proto = range.max_proto = exp->saved_proto;
	}
	nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);

	/* For DST manip, map port here to where it's expected. */
	range.flags = NF_NAT_RANGE_MAP_IPS;
	range.min_addr = range.max_addr
		= ct->master->tuplehash[!exp->dir].tuple.src.u3;
	if (exp->dir == IP_CT_DIR_REPLY) {
		range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
		range.min_proto = range.max_proto = exp->saved_proto;
	}
	nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST);
}

/* 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)

{
	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_data(ct);
	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:
		pr_debug("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 */
	pr_debug("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(skb, ct, ctinfo, protoff,
				     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)
{
	const 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_data(ct);
	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 *skb,
		 struct nf_conn *ct,
		 enum ip_conntrack_info ctinfo,
		 unsigned int protoff,
		 struct PptpControlHeader *ctlh,
		 union pptp_ctrl_union *pptpReq)
{
	const 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:
		pr_debug("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 */
	pr_debug("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(skb, ct, ctinfo, protoff,
				     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(nf_nat_pptp_hook_outbound != NULL);
	RCU_INIT_POINTER(nf_nat_pptp_hook_outbound, pptp_outbound_pkt);

	BUG_ON(nf_nat_pptp_hook_inbound != NULL);
	RCU_INIT_POINTER(nf_nat_pptp_hook_inbound, pptp_inbound_pkt);

	BUG_ON(nf_nat_pptp_hook_exp_gre != NULL);
	RCU_INIT_POINTER(nf_nat_pptp_hook_exp_gre, pptp_exp_gre);

	BUG_ON(nf_nat_pptp_hook_expectfn != NULL);
	RCU_INIT_POINTER(nf_nat_pptp_hook_expectfn, pptp_nat_expected);
	return 0;
}

static void __exit nf_nat_helper_pptp_fini(void)
{
	RCU_INIT_POINTER(nf_nat_pptp_hook_expectfn, NULL);
	RCU_INIT_POINTER(nf_nat_pptp_hook_exp_gre, NULL);
	RCU_INIT_POINTER(nf_nat_pptp_hook_inbound, NULL);
	RCU_INIT_POINTER(nf_nat_pptp_hook_outbound, NULL);
	synchronize_rcu();
}

module_init(nf_nat_helper_pptp_init);
module_exit(nf_nat_helper_pptp_fini);
Commit	Line	Data
f09943fe PM	1	/*
	2	* nf_nat_pptp.c
	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	*
f229f6ce PM	16	* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
f229f6ce PM	17	*
f09943fe PM	18	* TODO: - NAT to a unique tuple, not to TCP source port
	19	* (needs netfilter tuple reservation)
	20	*/
	21
	22	#include <linux/module.h>
	23	#include <linux/tcp.h>
	24
	25	#include <net/netfilter/nf_nat.h>
	26	#include <net/netfilter/nf_nat_helper.h>
f09943fe PM	27	#include <net/netfilter/nf_conntrack_helper.h>
f09943fe PM	28	#include <net/netfilter/nf_conntrack_expect.h>
5d0aa2cc	29	#include <net/netfilter/nf_conntrack_zones.h>
f09943fe PM	30	#include <linux/netfilter/nf_conntrack_proto_gre.h>
	31	#include <linux/netfilter/nf_conntrack_pptp.h>
	32
	33	#define NF_NAT_PPTP_VERSION "3.0"
	34
	35	#define REQ_CID(req, off) ((__be16 )((char *)(req) + (off)))
	36
	37	MODULE_LICENSE("GPL");
	38	MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
	39	MODULE_DESCRIPTION("Netfilter NAT helper module for PPTP");
	40	MODULE_ALIAS("ip_nat_pptp");
	41
f09943fe PM	42	static void pptp_nat_expected(struct nf_conn *ct,
	43	struct nf_conntrack_expect *exp)
	44	{
cfd6e3d7	45	struct net *net = nf_ct_net(ct);
9ddd0ed0	46	const struct nf_conn *master = ct->master;
f09943fe	47	struct nf_conntrack_expect *other_exp;
c255cb2e	48	struct nf_conntrack_tuple t = {};
9ddd0ed0 JE	49	const struct nf_ct_pptp_master *ct_pptp_info;
9ddd0ed0 JE	50	const struct nf_nat_pptp *nat_pptp_info;
c7232c99	51	struct nf_nat_range range;
f09943fe	52
1afc5679	53	ct_pptp_info = nfct_help_data(master);
f09943fe PM	54	nat_pptp_info = &nfct_nat(master)->help.nat_pptp_info;
	55
	56	/* And here goes the grand finale of corrosion... */
	57	if (exp->dir == IP_CT_DIR_ORIGINAL) {
0d53778e	58	pr_debug("we are PNS->PAC\n");
f09943fe PM	59	/* therefore, build tuple for PAC->PNS */
	60	t.src.l3num = AF_INET;
	61	t.src.u3.ip = master->tuplehash[!exp->dir].tuple.src.u3.ip;
	62	t.src.u.gre.key = ct_pptp_info->pac_call_id;
	63	t.dst.u3.ip = master->tuplehash[!exp->dir].tuple.dst.u3.ip;
	64	t.dst.u.gre.key = ct_pptp_info->pns_call_id;
	65	t.dst.protonum = IPPROTO_GRE;
	66	} else {
0d53778e	67	pr_debug("we are PAC->PNS\n");
f09943fe PM	68	/* build tuple for PNS->PAC */
f09943fe PM	69	t.src.l3num = AF_INET;
a46bf7d5	70	t.src.u3.ip = master->tuplehash[!exp->dir].tuple.src.u3.ip;
f09943fe	71	t.src.u.gre.key = nat_pptp_info->pns_call_id;
a46bf7d5	72	t.dst.u3.ip = master->tuplehash[!exp->dir].tuple.dst.u3.ip;
f09943fe PM	73	t.dst.u.gre.key = nat_pptp_info->pac_call_id;
	74	t.dst.protonum = IPPROTO_GRE;
	75	}
	76
0d53778e	77	pr_debug("trying to unexpect other dir: ");
3c9fba65	78	nf_ct_dump_tuple_ip(&t);
5d0aa2cc	79	other_exp = nf_ct_expect_find_get(net, nf_ct_zone(ct), &t);
f09943fe	80	if (other_exp) {
6823645d PM	81	nf_ct_unexpect_related(other_exp);
6823645d PM	82	nf_ct_expect_put(other_exp);
0d53778e	83	pr_debug("success\n");
f09943fe	84	} else {
0d53778e	85	pr_debug("not found!\n");
f09943fe PM	86	}
	87
	88	/* This must be a fresh one. */
	89	BUG_ON(ct->status & IPS_NAT_DONE_MASK);
	90
	91	/* Change src to where master sends to */
cbc9f2f4	92	range.flags = NF_NAT_RANGE_MAP_IPS;
c7232c99 PM	93	range.min_addr = range.max_addr
c7232c99 PM	94	= ct->master->tuplehash[!exp->dir].tuple.dst.u3;
f09943fe	95	if (exp->dir == IP_CT_DIR_ORIGINAL) {
cbc9f2f4	96	range.flags \|= NF_NAT_RANGE_PROTO_SPECIFIED;
c7232c99	97	range.min_proto = range.max_proto = exp->saved_proto;
f09943fe	98	}
cbc9f2f4	99	nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);
f09943fe PM	100
f09943fe PM	101	/* For DST manip, map port here to where it's expected. */
cbc9f2f4	102	range.flags = NF_NAT_RANGE_MAP_IPS;
c7232c99 PM	103	range.min_addr = range.max_addr
c7232c99 PM	104	= ct->master->tuplehash[!exp->dir].tuple.src.u3;
f09943fe	105	if (exp->dir == IP_CT_DIR_REPLY) {
cbc9f2f4	106	range.flags \|= NF_NAT_RANGE_PROTO_SPECIFIED;
c7232c99	107	range.min_proto = range.max_proto = exp->saved_proto;
f09943fe	108	}
cbc9f2f4	109	nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST);
f09943fe PM	110	}
	111
	112	/* outbound packets == from PNS to PAC */
	113	static int
3db05fea	114	pptp_outbound_pkt(struct sk_buff *skb,
f09943fe PM	115	struct nf_conn *ct,
f09943fe PM	116	enum ip_conntrack_info ctinfo,
051966c0	117	unsigned int protoff,
f09943fe PM	118	struct PptpControlHeader *ctlh,
	119	union pptp_ctrl_union *pptpReq)
	120
	121	{
	122	struct nf_ct_pptp_master *ct_pptp_info;
	123	struct nf_nat_pptp *nat_pptp_info;
	124	u_int16_t msg;
	125	__be16 new_callid;
	126	unsigned int cid_off;
	127
1afc5679	128	ct_pptp_info = nfct_help_data(ct);
f09943fe PM	129	nat_pptp_info = &nfct_nat(ct)->help.nat_pptp_info;
	130
	131	new_callid = ct_pptp_info->pns_call_id;
	132
	133	switch (msg = ntohs(ctlh->messageType)) {
	134	case PPTP_OUT_CALL_REQUEST:
	135	cid_off = offsetof(union pptp_ctrl_union, ocreq.callID);
	136	/* FIXME: ideally we would want to reserve a call ID
	137	* here. current netfilter NAT core is not able to do
	138	* this :( For now we use TCP source port. This breaks
	139	* multiple calls within one control session */
	140
	141	/* save original call ID in nat_info */
	142	nat_pptp_info->pns_call_id = ct_pptp_info->pns_call_id;
	143
	144	/* don't use tcph->source since we are at a DSTmanip
	145	* hook (e.g. PREROUTING) and pkt is not mangled yet */
	146	new_callid = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.tcp.port;
	147
	148	/* save new call ID in ct info */
	149	ct_pptp_info->pns_call_id = new_callid;
	150	break;
	151	case PPTP_IN_CALL_REPLY:
	152	cid_off = offsetof(union pptp_ctrl_union, icack.callID);
	153	break;
	154	case PPTP_CALL_CLEAR_REQUEST:
	155	cid_off = offsetof(union pptp_ctrl_union, clrreq.callID);
	156	break;
	157	default:
0d53778e PM	158	pr_debug("unknown outbound packet 0x%04x:%s\n", msg,
	159	msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] :
	160	pptp_msg_name[0]);
f09943fe PM	161	/* fall through */
	162	case PPTP_SET_LINK_INFO:
	163	/* only need to NAT in case PAC is behind NAT box */
	164	case PPTP_START_SESSION_REQUEST:
	165	case PPTP_START_SESSION_REPLY:
	166	case PPTP_STOP_SESSION_REQUEST:
	167	case PPTP_STOP_SESSION_REPLY:
	168	case PPTP_ECHO_REQUEST:
	169	case PPTP_ECHO_REPLY:
	170	/* no need to alter packet */
	171	return NF_ACCEPT;
	172	}
	173
	174	/* only OUT_CALL_REQUEST, IN_CALL_REPLY, CALL_CLEAR_REQUEST pass
	175	* down to here */
0d53778e PM	176	pr_debug("altering call id from 0x%04x to 0x%04x\n",
0d53778e PM	177	ntohs(REQ_CID(pptpReq, cid_off)), ntohs(new_callid));
f09943fe PM	178
f09943fe PM	179	/* mangle packet */
051966c0	180	if (nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff,
e905a9ed YH	181	cid_off + sizeof(struct pptp_pkt_hdr) +
	182	sizeof(struct PptpControlHeader),
	183	sizeof(new_callid), (char *)&new_callid,
	184	sizeof(new_callid)) == 0)
f09943fe PM	185	return NF_DROP;
	186	return NF_ACCEPT;
	187	}
	188
	189	static void
	190	pptp_exp_gre(struct nf_conntrack_expect *expect_orig,
	191	struct nf_conntrack_expect *expect_reply)
	192	{
9ddd0ed0	193	const struct nf_conn *ct = expect_orig->master;
f09943fe PM	194	struct nf_ct_pptp_master *ct_pptp_info;
	195	struct nf_nat_pptp *nat_pptp_info;
	196
1afc5679	197	ct_pptp_info = nfct_help_data(ct);
f09943fe PM	198	nat_pptp_info = &nfct_nat(ct)->help.nat_pptp_info;
	199
	200	/* save original PAC call ID in nat_info */
	201	nat_pptp_info->pac_call_id = ct_pptp_info->pac_call_id;
	202
	203	/* alter expectation for PNS->PAC direction */
	204	expect_orig->saved_proto.gre.key = ct_pptp_info->pns_call_id;
	205	expect_orig->tuple.src.u.gre.key = nat_pptp_info->pns_call_id;
	206	expect_orig->tuple.dst.u.gre.key = ct_pptp_info->pac_call_id;
	207	expect_orig->dir = IP_CT_DIR_ORIGINAL;
	208
	209	/* alter expectation for PAC->PNS direction */
	210	expect_reply->saved_proto.gre.key = nat_pptp_info->pns_call_id;
	211	expect_reply->tuple.src.u.gre.key = nat_pptp_info->pac_call_id;
	212	expect_reply->tuple.dst.u.gre.key = ct_pptp_info->pns_call_id;
	213	expect_reply->dir = IP_CT_DIR_REPLY;
	214	}
	215
	216	/* inbound packets == from PAC to PNS */
	217	static int
3db05fea	218	pptp_inbound_pkt(struct sk_buff *skb,
f09943fe PM	219	struct nf_conn *ct,
f09943fe PM	220	enum ip_conntrack_info ctinfo,
051966c0	221	unsigned int protoff,
f09943fe PM	222	struct PptpControlHeader *ctlh,
	223	union pptp_ctrl_union *pptpReq)
	224	{
9ddd0ed0	225	const struct nf_nat_pptp *nat_pptp_info;
f09943fe PM	226	u_int16_t msg;
	227	__be16 new_pcid;
	228	unsigned int pcid_off;
	229
	230	nat_pptp_info = &nfct_nat(ct)->help.nat_pptp_info;
	231	new_pcid = nat_pptp_info->pns_call_id;
	232
	233	switch (msg = ntohs(ctlh->messageType)) {
	234	case PPTP_OUT_CALL_REPLY:
	235	pcid_off = offsetof(union pptp_ctrl_union, ocack.peersCallID);
	236	break;
	237	case PPTP_IN_CALL_CONNECT:
	238	pcid_off = offsetof(union pptp_ctrl_union, iccon.peersCallID);
	239	break;
	240	case PPTP_IN_CALL_REQUEST:
	241	/* only need to nat in case PAC is behind NAT box */
	242	return NF_ACCEPT;
	243	case PPTP_WAN_ERROR_NOTIFY:
	244	pcid_off = offsetof(union pptp_ctrl_union, wanerr.peersCallID);
	245	break;
	246	case PPTP_CALL_DISCONNECT_NOTIFY:
	247	pcid_off = offsetof(union pptp_ctrl_union, disc.callID);
	248	break;
	249	case PPTP_SET_LINK_INFO:
	250	pcid_off = offsetof(union pptp_ctrl_union, setlink.peersCallID);
	251	break;
	252	default:
0d53778e PM	253	pr_debug("unknown inbound packet %s\n",
	254	msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] :
	255	pptp_msg_name[0]);
f09943fe PM	256	/* fall through */
	257	case PPTP_START_SESSION_REQUEST:
	258	case PPTP_START_SESSION_REPLY:
	259	case PPTP_STOP_SESSION_REQUEST:
	260	case PPTP_STOP_SESSION_REPLY:
	261	case PPTP_ECHO_REQUEST:
	262	case PPTP_ECHO_REPLY:
	263	/* no need to alter packet */
	264	return NF_ACCEPT;
	265	}
	266
	267	/* only OUT_CALL_REPLY, IN_CALL_CONNECT, IN_CALL_REQUEST,
	268	* WAN_ERROR_NOTIFY, CALL_DISCONNECT_NOTIFY pass down here */
	269
	270	/* mangle packet */
0d53778e PM	271	pr_debug("altering peer call id from 0x%04x to 0x%04x\n",
0d53778e PM	272	ntohs(REQ_CID(pptpReq, pcid_off)), ntohs(new_pcid));
f09943fe	273
051966c0	274	if (nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff,
e905a9ed	275	pcid_off + sizeof(struct pptp_pkt_hdr) +
f09943fe PM	276	sizeof(struct PptpControlHeader),
	277	sizeof(new_pcid), (char *)&new_pcid,
	278	sizeof(new_pcid)) == 0)
	279	return NF_DROP;
	280	return NF_ACCEPT;
	281	}
	282
	283	static int __init nf_nat_helper_pptp_init(void)
	284	{
	285	nf_nat_need_gre();
	286
d1332e0a	287	BUG_ON(nf_nat_pptp_hook_outbound != NULL);
a9b3cd7f	288	RCU_INIT_POINTER(nf_nat_pptp_hook_outbound, pptp_outbound_pkt);
f09943fe	289
d1332e0a	290	BUG_ON(nf_nat_pptp_hook_inbound != NULL);
a9b3cd7f	291	RCU_INIT_POINTER(nf_nat_pptp_hook_inbound, pptp_inbound_pkt);
f09943fe	292
d1332e0a	293	BUG_ON(nf_nat_pptp_hook_exp_gre != NULL);
a9b3cd7f	294	RCU_INIT_POINTER(nf_nat_pptp_hook_exp_gre, pptp_exp_gre);
f09943fe	295
d1332e0a	296	BUG_ON(nf_nat_pptp_hook_expectfn != NULL);
a9b3cd7f	297	RCU_INIT_POINTER(nf_nat_pptp_hook_expectfn, pptp_nat_expected);
f09943fe PM	298	return 0;
	299	}
	300
	301	static void __exit nf_nat_helper_pptp_fini(void)
	302	{
a9b3cd7f SH	303	RCU_INIT_POINTER(nf_nat_pptp_hook_expectfn, NULL);
	304	RCU_INIT_POINTER(nf_nat_pptp_hook_exp_gre, NULL);
	305	RCU_INIT_POINTER(nf_nat_pptp_hook_inbound, NULL);
	306	RCU_INIT_POINTER(nf_nat_pptp_hook_outbound, NULL);
f09943fe PM	307	synchronize_rcu();
	308	}
	309
	310	module_init(nf_nat_helper_pptp_init);
	311	module_exit(nf_nat_helper_pptp_fini);