2006-12-03 14:09:41 +08:00
|
|
|
/*
|
|
|
|
* 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;
|
2007-03-15 07:37:25 +08:00
|
|
|
struct nf_nat_range range;
|
2006-12-03 14:09:41 +08:00
|
|
|
|
|
|
|
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;
|
2007-01-26 17:07:30 +08:00
|
|
|
t.src.u3.ip = master->tuplehash[!exp->dir].tuple.src.u3.ip;
|
2006-12-03 14:09:41 +08:00
|
|
|
t.src.u.gre.key = nat_pptp_info->pns_call_id;
|
2007-01-26 17:07:30 +08:00
|
|
|
t.dst.u3.ip = master->tuplehash[!exp->dir].tuple.dst.u3.ip;
|
2006-12-03 14:09:41 +08:00
|
|
|
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,
|
2007-02-09 22:24:47 +08:00
|
|
|
cid_off + sizeof(struct pptp_pkt_hdr) +
|
|
|
|
sizeof(struct PptpControlHeader),
|
|
|
|
sizeof(new_callid), (char *)&new_callid,
|
|
|
|
sizeof(new_callid)) == 0)
|
2006-12-03 14:09:41 +08:00
|
|
|
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,
|
2007-02-09 22:24:47 +08:00
|
|
|
pcid_off + sizeof(struct pptp_pkt_hdr) +
|
2006-12-03 14:09:41 +08:00
|
|
|
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);
|