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[NETFILTER]: nf_conntrack/nf_nat: add PPTP helper port

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Add nf_conntrack port of the PPtP conntrack/NAT helper. Since there seems
to be no IPv6-capable PPtP implementation the helper only support IPv4.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy
2006-12-02 22:09:41 -08:00
committed by David S. Miller
parent 92703eee4c
commit f09943fefe
15 changed files with 1896 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
net/ipv4/netfilter/Kconfig
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@@ -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

4
net/ipv4/netfilter/Makefile
View File

@@ -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

315
net/ipv4/netfilter/nf_nat_pptp.c Normal file
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@@ -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);

179
net/ipv4/netfilter/nf_nat_proto_gre.c Normal file
View File

@@ -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;
case GRE_VERSION_PPTP:
DEBUGP("call_id -> 0x%04x\n", ntohs(tuple->dst.u.gre.key));
pgreh->call_id = tuple->dst.u.gre.key;
break;
default:
DEBUGP("can't nat unknown GRE version\n");
return 0;
}
return 1;
}
static struct nf_nat_protocol gre __read_mostly = {
.name = "GRE",
.protonum = IPPROTO_GRE,
.manip_pkt = gre_manip_pkt,
.in_range = gre_in_range,
.unique_tuple = gre_unique_tuple,
#if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \
defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE)
.range_to_nfattr = nf_nat_port_range_to_nfattr,
.nfattr_to_range = nf_nat_port_nfattr_to_range,
#endif
};
int __init nf_nat_proto_gre_init(void)
{
return nf_nat_protocol_register(&gre);
}
void __exit nf_nat_proto_gre_fini(void)
{
nf_nat_protocol_unregister(&gre);
}
module_init(nf_nat_proto_gre_init);
module_exit(nf_nat_proto_gre_fini);
void nf_nat_need_gre(void)
{
return;
}
EXPORT_SYMBOL_GPL(nf_nat_need_gre);