BackPup/Linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-15 15:01:08 -04:00
Code Issues Packages Projects Releases Wiki Activity

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

Browse Source 
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

23
net/netfilter/Kconfig
View File

@@ -120,6 +120,10 @@ config NF_CONNTRACK_EVENTS
If unsure, say `N'.
config NF_CT_PROTO_GRE
tristate
depends on EXPERIMENTAL && NF_CONNTRACK
config NF_CT_PROTO_SCTP
tristate 'SCTP protocol on new connection tracking support (EXPERIMENTAL)'
depends on EXPERIMENTAL && NF_CONNTRACK
@@ -213,6 +217,25 @@ config NF_CONNTRACK_NETBIOS_NS
To compile it as a module, choose M here. If unsure, say N.
config NF_CONNTRACK_PPTP
tristate "PPtP protocol support (EXPERIMENTAL)"
depends on EXPERIMENTAL && NF_CONNTRACK
select NF_CT_PROTO_GRE
help
This module adds support for PPTP (Point to Point Tunnelling
Protocol, RFC2637) connection tracking and NAT.
If you are running PPTP sessions over a stateful firewall or NAT
box, you may want to enable this feature.
Please note that not all PPTP modes of operation are supported yet.
Specifically these limitations exist:
- Blindy assumes that control connections are always established
in PNS->PAC direction. This is a violation of RFC2637.
- Only supports a single call within each session
To compile it as a module, choose M here. If unsure, say N.
config NF_CT_NETLINK
tristate 'Connection tracking netlink interface (EXPERIMENTAL)'
depends on EXPERIMENTAL && NF_CONNTRACK && NETFILTER_NETLINK

2
net/netfilter/Makefile
View File

@@ -14,6 +14,7 @@ obj-$(CONFIG_NETFILTER_NETLINK_LOG) += nfnetlink_log.o
obj-$(CONFIG_NF_CONNTRACK) += nf_conntrack.o
# SCTP protocol connection tracking
obj-$(CONFIG_NF_CT_PROTO_GRE) += nf_conntrack_proto_gre.o
obj-$(CONFIG_NF_CT_PROTO_SCTP) += nf_conntrack_proto_sctp.o
# netlink interface for nf_conntrack
@@ -27,6 +28,7 @@ obj-$(CONFIG_NF_CONNTRACK_FTP) += nf_conntrack_ftp.o
obj-$(CONFIG_NF_CONNTRACK_H323) += nf_conntrack_h323.o
obj-$(CONFIG_NF_CONNTRACK_IRC) += nf_conntrack_irc.o
obj-$(CONFIG_NF_CONNTRACK_NETBIOS_NS) += nf_conntrack_netbios_ns.o
obj-$(CONFIG_NF_CONNTRACK_PPTP) += nf_conntrack_pptp.o
# generic X tables
obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o

4
net/netfilter/nf_conntrack_core.c
View File

@@ -300,6 +300,7 @@ static void
destroy_conntrack(struct nf_conntrack *nfct)
{
struct nf_conn *ct = (struct nf_conn *)nfct;
struct nf_conn_help *help = nfct_help(ct);
struct nf_conntrack_l3proto *l3proto;
struct nf_conntrack_l4proto *l4proto;
@@ -310,6 +311,9 @@ destroy_conntrack(struct nf_conntrack *nfct)
nf_conntrack_event(IPCT_DESTROY, ct);
set_bit(IPS_DYING_BIT, &ct->status);
if (help && help->helper && help->helper->destroy)
help->helper->destroy(ct);
/* To make sure we don't get any weird locking issues here:
* destroy_conntrack() MUST NOT be called with a write lock
* to nf_conntrack_lock!!! -HW */

607
net/netfilter/nf_conntrack_pptp.c Normal file
View File

@@ -0,0 +1,607 @@
/*
* Connection tracking 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/)
*
* Limitations:
* - We blindly assume that control connections are always
* established in PNS->PAC direction. This is a violation
* of RFFC2673
* - We can only support one single call within each session
* TODO:
* - testing of incoming PPTP calls
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <linux/netfilter/nf_conntrack_proto_gre.h>
#include <linux/netfilter/nf_conntrack_pptp.h>
#define NF_CT_PPTP_VERSION "3.1"
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP");
MODULE_ALIAS("ip_conntrack_pptp");
static DEFINE_SPINLOCK(nf_pptp_lock);
int
(*nf_nat_pptp_hook_outbound)(struct sk_buff **pskb,
struct nf_conn *ct, enum ip_conntrack_info ctinfo,
struct PptpControlHeader *ctlh,
union pptp_ctrl_union *pptpReq) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_outbound);
int
(*nf_nat_pptp_hook_inbound)(struct sk_buff **pskb,
struct nf_conn *ct, enum ip_conntrack_info ctinfo,
struct PptpControlHeader *ctlh,
union pptp_ctrl_union *pptpReq) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_inbound);
void
(*nf_nat_pptp_hook_exp_gre)(struct nf_conntrack_expect *expect_orig,
struct nf_conntrack_expect *expect_reply)
__read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_exp_gre);
void
(*nf_nat_pptp_hook_expectfn)(struct nf_conn *ct,
struct nf_conntrack_expect *exp) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn);
#if 0
/* PptpControlMessageType names */
const char *pptp_msg_name[] = {
"UNKNOWN_MESSAGE",
"START_SESSION_REQUEST",
"START_SESSION_REPLY",
"STOP_SESSION_REQUEST",
"STOP_SESSION_REPLY",
"ECHO_REQUEST",
"ECHO_REPLY",
"OUT_CALL_REQUEST",
"OUT_CALL_REPLY",
"IN_CALL_REQUEST",
"IN_CALL_REPLY",
"IN_CALL_CONNECT",
"CALL_CLEAR_REQUEST",
"CALL_DISCONNECT_NOTIFY",
"WAN_ERROR_NOTIFY",
"SET_LINK_INFO"
};
EXPORT_SYMBOL(pptp_msg_name);
#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, __FUNCTION__, ## args)
#else
#define DEBUGP(format, args...)
#endif
#define SECS *HZ
#define MINS * 60 SECS
#define HOURS * 60 MINS
#define PPTP_GRE_TIMEOUT (10 MINS)
#define PPTP_GRE_STREAM_TIMEOUT (5 HOURS)
static void pptp_expectfn(struct nf_conn *ct,
struct nf_conntrack_expect *exp)
{
typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn;
DEBUGP("increasing timeouts\n");
/* increase timeout of GRE data channel conntrack entry */
ct->proto.gre.timeout = PPTP_GRE_TIMEOUT;
ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT;
/* Can you see how rusty this code is, compared with the pre-2.6.11
* one? That's what happened to my shiny newnat of 2002 ;( -HW */
rcu_read_lock();
nf_nat_pptp_expectfn = rcu_dereference(nf_nat_pptp_hook_expectfn);
if (nf_nat_pptp_expectfn && ct->status & IPS_NAT_MASK)
nf_nat_pptp_expectfn(ct, exp);
else {
struct nf_conntrack_tuple inv_t;
struct nf_conntrack_expect *exp_other;
/* obviously this tuple inversion only works until you do NAT */
nf_ct_invert_tuplepr(&inv_t, &exp->tuple);
DEBUGP("trying to unexpect other dir: ");
NF_CT_DUMP_TUPLE(&inv_t);
exp_other = nf_conntrack_expect_find_get(&inv_t);
if (exp_other) {
/* delete other expectation. */
DEBUGP("found\n");
nf_conntrack_unexpect_related(exp_other);
nf_conntrack_expect_put(exp_other);
} else {
DEBUGP("not found\n");
}
}
rcu_read_unlock();
}
static int destroy_sibling_or_exp(const struct nf_conntrack_tuple *t)
{
struct nf_conntrack_tuple_hash *h;
struct nf_conntrack_expect *exp;
struct nf_conn *sibling;
DEBUGP("trying to timeout ct or exp for tuple ");
NF_CT_DUMP_TUPLE(t);
h = nf_conntrack_find_get(t, NULL);
if (h) {
sibling = nf_ct_tuplehash_to_ctrack(h);
DEBUGP("setting timeout of conntrack %p to 0\n", sibling);
sibling->proto.gre.timeout = 0;
sibling->proto.gre.stream_timeout = 0;
if (del_timer(&sibling->timeout))
sibling->timeout.function((unsigned long)sibling);
nf_ct_put(sibling);
return 1;
} else {
exp = nf_conntrack_expect_find_get(t);
if (exp) {
DEBUGP("unexpect_related of expect %p\n", exp);
nf_conntrack_unexpect_related(exp);
nf_conntrack_expect_put(exp);
return 1;
}
}
return 0;
}
/* timeout GRE data connections */
static void pptp_destroy_siblings(struct nf_conn *ct)
{
struct nf_conn_help *help = nfct_help(ct);
struct nf_conntrack_tuple t;
nf_ct_gre_keymap_destroy(ct);
/* try original (pns->pac) tuple */
memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t));
t.dst.protonum = IPPROTO_GRE;
t.src.u.gre.key = help->help.ct_pptp_info.pns_call_id;
t.dst.u.gre.key = help->help.ct_pptp_info.pac_call_id;
if (!destroy_sibling_or_exp(&t))
DEBUGP("failed to timeout original pns->pac ct/exp\n");
/* try reply (pac->pns) tuple */
memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t));
t.dst.protonum = IPPROTO_GRE;
t.src.u.gre.key = help->help.ct_pptp_info.pac_call_id;
t.dst.u.gre.key = help->help.ct_pptp_info.pns_call_id;
if (!destroy_sibling_or_exp(&t))
DEBUGP("failed to timeout reply pac->pns ct/exp\n");
}
/* expect GRE connections (PNS->PAC and PAC->PNS direction) */
static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid)
{
struct nf_conntrack_expect *exp_orig, *exp_reply;
enum ip_conntrack_dir dir;
int ret = 1;
typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre;
exp_orig = nf_conntrack_expect_alloc(ct);
if (exp_orig == NULL)
goto out;
exp_reply = nf_conntrack_expect_alloc(ct);
if (exp_reply == NULL)
goto out_put_orig;
/* original direction, PNS->PAC */
dir = IP_CT_DIR_ORIGINAL;
nf_conntrack_expect_init(exp_orig, ct->tuplehash[dir].tuple.src.l3num,
&ct->tuplehash[dir].tuple.src.u3,
&ct->tuplehash[dir].tuple.dst.u3,
IPPROTO_GRE, &peer_callid, &callid);
exp_orig->expectfn = pptp_expectfn;
/* reply direction, PAC->PNS */
dir = IP_CT_DIR_REPLY;
nf_conntrack_expect_init(exp_reply, ct->tuplehash[dir].tuple.src.l3num,
&ct->tuplehash[dir].tuple.src.u3,
&ct->tuplehash[dir].tuple.dst.u3,
IPPROTO_GRE, &callid, &peer_callid);
exp_reply->expectfn = pptp_expectfn;
nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre);
if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK)
nf_nat_pptp_exp_gre(exp_orig, exp_reply);
if (nf_conntrack_expect_related(exp_orig) != 0)
goto out_put_both;
if (nf_conntrack_expect_related(exp_reply) != 0)
goto out_unexpect_orig;
/* Add GRE keymap entries */
if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0)
goto out_unexpect_both;
if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) {
nf_ct_gre_keymap_destroy(ct);
goto out_unexpect_both;
}
ret = 0;
out_put_both:
nf_conntrack_expect_put(exp_reply);
out_put_orig:
nf_conntrack_expect_put(exp_orig);
out:
return ret;
out_unexpect_both:
nf_conntrack_unexpect_related(exp_reply);
out_unexpect_orig:
nf_conntrack_unexpect_related(exp_orig);
goto out_put_both;
}
static inline int
pptp_inbound_pkt(struct sk_buff **pskb,
struct PptpControlHeader *ctlh,
union pptp_ctrl_union *pptpReq,
unsigned int reqlen,
struct nf_conn *ct,
enum ip_conntrack_info ctinfo)
{
struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info;
u_int16_t msg;
__be16 cid = 0, pcid = 0;
typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound;
msg = ntohs(ctlh->messageType);
DEBUGP("inbound control message %s\n", pptp_msg_name[msg]);
switch (msg) {
case PPTP_START_SESSION_REPLY:
/* server confirms new control session */
if (info->sstate < PPTP_SESSION_REQUESTED)
goto invalid;
if (pptpReq->srep.resultCode == PPTP_START_OK)
info->sstate = PPTP_SESSION_CONFIRMED;
else
info->sstate = PPTP_SESSION_ERROR;
break;
case PPTP_STOP_SESSION_REPLY:
/* server confirms end of control session */
if (info->sstate > PPTP_SESSION_STOPREQ)
goto invalid;
if (pptpReq->strep.resultCode == PPTP_STOP_OK)
info->sstate = PPTP_SESSION_NONE;
else
info->sstate = PPTP_SESSION_ERROR;
break;
case PPTP_OUT_CALL_REPLY:
/* server accepted call, we now expect GRE frames */
if (info->sstate != PPTP_SESSION_CONFIRMED)
goto invalid;
if (info->cstate != PPTP_CALL_OUT_REQ &&
info->cstate != PPTP_CALL_OUT_CONF)
goto invalid;
cid = pptpReq->ocack.callID;
pcid = pptpReq->ocack.peersCallID;
if (info->pns_call_id != pcid)
goto invalid;
DEBUGP("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg],
ntohs(cid), ntohs(pcid));
if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) {
info->cstate = PPTP_CALL_OUT_CONF;
info->pac_call_id = cid;
exp_gre(ct, cid, pcid);
} else
info->cstate = PPTP_CALL_NONE;
break;
case PPTP_IN_CALL_REQUEST:
/* server tells us about incoming call request */
if (info->sstate != PPTP_SESSION_CONFIRMED)
goto invalid;
cid = pptpReq->icreq.callID;
DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
info->cstate = PPTP_CALL_IN_REQ;
info->pac_call_id = cid;
break;
case PPTP_IN_CALL_CONNECT:
/* server tells us about incoming call established */
if (info->sstate != PPTP_SESSION_CONFIRMED)
goto invalid;
if (info->cstate != PPTP_CALL_IN_REP &&
info->cstate != PPTP_CALL_IN_CONF)
goto invalid;
pcid = pptpReq->iccon.peersCallID;
cid = info->pac_call_id;
if (info->pns_call_id != pcid)
goto invalid;
DEBUGP("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid));
info->cstate = PPTP_CALL_IN_CONF;
/* we expect a GRE connection from PAC to PNS */
exp_gre(ct, cid, pcid);
break;
case PPTP_CALL_DISCONNECT_NOTIFY:
/* server confirms disconnect */
cid = pptpReq->disc.callID;
DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
info->cstate = PPTP_CALL_NONE;
/* untrack this call id, unexpect GRE packets */
pptp_destroy_siblings(ct);
break;
case PPTP_WAN_ERROR_NOTIFY:
case PPTP_ECHO_REQUEST:
case PPTP_ECHO_REPLY:
/* I don't have to explain these ;) */
break;
default:
goto invalid;
}
nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound);
if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK)
return nf_nat_pptp_inbound(pskb, ct, ctinfo, ctlh, pptpReq);
return NF_ACCEPT;
invalid:
DEBUGP("invalid %s: type=%d cid=%u pcid=%u "
"cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
ntohs(info->pns_call_id), ntohs(info->pac_call_id));
return NF_ACCEPT;
}
static inline int
pptp_outbound_pkt(struct sk_buff **pskb,
struct PptpControlHeader *ctlh,
union pptp_ctrl_union *pptpReq,
unsigned int reqlen,
struct nf_conn *ct,
enum ip_conntrack_info ctinfo)
{
struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info;
u_int16_t msg;
__be16 cid = 0, pcid = 0;
typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound;
msg = ntohs(ctlh->messageType);
DEBUGP("outbound control message %s\n", pptp_msg_name[msg]);
switch (msg) {
case PPTP_START_SESSION_REQUEST:
/* client requests for new control session */
if (info->sstate != PPTP_SESSION_NONE)
goto invalid;
info->sstate = PPTP_SESSION_REQUESTED;
break;
case PPTP_STOP_SESSION_REQUEST:
/* client requests end of control session */
info->sstate = PPTP_SESSION_STOPREQ;
break;
case PPTP_OUT_CALL_REQUEST:
/* client initiating connection to server */
if (info->sstate != PPTP_SESSION_CONFIRMED)
goto invalid;
info->cstate = PPTP_CALL_OUT_REQ;
/* track PNS call id */
cid = pptpReq->ocreq.callID;
DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
info->pns_call_id = cid;
break;
case PPTP_IN_CALL_REPLY:
/* client answers incoming call */
if (info->cstate != PPTP_CALL_IN_REQ &&
info->cstate != PPTP_CALL_IN_REP)
goto invalid;
cid = pptpReq->icack.callID;
pcid = pptpReq->icack.peersCallID;
if (info->pac_call_id != pcid)
goto invalid;
DEBUGP("%s, CID=%X PCID=%X\n", pptp_msg_name[msg],
ntohs(cid), ntohs(pcid));
if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
/* part two of the three-way handshake */
info->cstate = PPTP_CALL_IN_REP;
info->pns_call_id = cid;
} else
info->cstate = PPTP_CALL_NONE;
break;
case PPTP_CALL_CLEAR_REQUEST:
/* client requests hangup of call */
if (info->sstate != PPTP_SESSION_CONFIRMED)
goto invalid;
/* FUTURE: iterate over all calls and check if
* call ID is valid. We don't do this without newnat,
* because we only know about last call */
info->cstate = PPTP_CALL_CLEAR_REQ;
break;
case PPTP_SET_LINK_INFO:
case PPTP_ECHO_REQUEST:
case PPTP_ECHO_REPLY:
/* I don't have to explain these ;) */
break;
default:
goto invalid;
}
nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound);
if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK)
return nf_nat_pptp_outbound(pskb, ct, ctinfo, ctlh, pptpReq);
return NF_ACCEPT;
invalid:
DEBUGP("invalid %s: type=%d cid=%u pcid=%u "
"cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
ntohs(info->pns_call_id), ntohs(info->pac_call_id));
return NF_ACCEPT;
}
static const unsigned int pptp_msg_size[] = {
[PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest),
[PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply),
[PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest),
[PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply),
[PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest),
[PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply),
[PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest),
[PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply),
[PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected),
[PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest),
[PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
[PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify),
[PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo),
};
/* track caller id inside control connection, call expect_related */
static int
conntrack_pptp_help(struct sk_buff **pskb, unsigned int protoff,
struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
int dir = CTINFO2DIR(ctinfo);
struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info;
struct tcphdr _tcph, *tcph;
struct pptp_pkt_hdr _pptph, *pptph;
struct PptpControlHeader _ctlh, *ctlh;
union pptp_ctrl_union _pptpReq, *pptpReq;
unsigned int tcplen = (*pskb)->len - protoff;
unsigned int datalen, reqlen, nexthdr_off;
int oldsstate, oldcstate;
int ret;
u_int16_t msg;
/* don't do any tracking before tcp handshake complete */
if (ctinfo != IP_CT_ESTABLISHED &&
ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
return NF_ACCEPT;
nexthdr_off = protoff;
tcph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_tcph), &_tcph);
BUG_ON(!tcph);
nexthdr_off += tcph->doff * 4;
datalen = tcplen - tcph->doff * 4;
pptph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_pptph), &_pptph);
if (!pptph) {
DEBUGP("no full PPTP header, can't track\n");
return NF_ACCEPT;
}
nexthdr_off += sizeof(_pptph);
datalen -= sizeof(_pptph);
/* if it's not a control message we can't do anything with it */
if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL ||
ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) {
DEBUGP("not a control packet\n");
return NF_ACCEPT;
}
ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh);
if (!ctlh)
return NF_ACCEPT;
nexthdr_off += sizeof(_ctlh);
datalen -= sizeof(_ctlh);
reqlen = datalen;
msg = ntohs(ctlh->messageType);
if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
return NF_ACCEPT;
if (reqlen > sizeof(*pptpReq))
reqlen = sizeof(*pptpReq);
pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq);
if (!pptpReq)
return NF_ACCEPT;
oldsstate = info->sstate;
oldcstate = info->cstate;
spin_lock_bh(&nf_pptp_lock);
/* FIXME: We just blindly assume that the control connection is always
* established from PNS->PAC. However, RFC makes no guarantee */
if (dir == IP_CT_DIR_ORIGINAL)
/* client -> server (PNS -> PAC) */
ret = pptp_outbound_pkt(pskb, ctlh, pptpReq, reqlen, ct,
ctinfo);
else
/* server -> client (PAC -> PNS) */
ret = pptp_inbound_pkt(pskb, ctlh, pptpReq, reqlen, ct,
ctinfo);
DEBUGP("sstate: %d->%d, cstate: %d->%d\n",
oldsstate, info->sstate, oldcstate, info->cstate);
spin_unlock_bh(&nf_pptp_lock);
return ret;
}
/* control protocol helper */
static struct nf_conntrack_helper pptp __read_mostly = {
.name = "pptp",
.me = THIS_MODULE,
.max_expected = 2,
.timeout = 5 * 60,
.tuple.src.l3num = AF_INET,
.tuple.src.u.tcp.port = __constant_htons(PPTP_CONTROL_PORT),
.tuple.dst.protonum = IPPROTO_TCP,
.mask.src.l3num = 0xffff,
.mask.src.u.tcp.port = __constant_htons(0xffff),
.mask.dst.protonum = 0xff,
.help = conntrack_pptp_help,
.destroy = pptp_destroy_siblings,
};
static int __init nf_conntrack_pptp_init(void)
{
return nf_conntrack_helper_register(&pptp);
}
static void __exit nf_conntrack_pptp_fini(void)
{
nf_conntrack_helper_unregister(&pptp);
nf_ct_gre_keymap_flush();
}
module_init(nf_conntrack_pptp_init);
module_exit(nf_conntrack_pptp_fini);

305
net/netfilter/nf_conntrack_proto_gre.c Normal file
View File

@@ -0,0 +1,305 @@
/*
* ip_conntrack_proto_gre.c - Version 3.0
*
* Connection tracking 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/types.h>
#include <linux/timer.h>
#include <linux/list.h>
#include <linux/seq_file.h>
#include <linux/in.h>
#include <linux/skbuff.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <linux/netfilter/nf_conntrack_proto_gre.h>
#include <linux/netfilter/nf_conntrack_pptp.h>
#define GRE_TIMEOUT (30 * HZ)
#define GRE_STREAM_TIMEOUT (180 * HZ)
#if 0
#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, __FUNCTION__, ## args)
#else
#define DEBUGP(x, args...)
#endif
static DEFINE_RWLOCK(nf_ct_gre_lock);
static LIST_HEAD(gre_keymap_list);
void nf_ct_gre_keymap_flush(void)
{
struct list_head *pos, *n;
write_lock_bh(&nf_ct_gre_lock);
list_for_each_safe(pos, n, &gre_keymap_list) {
list_del(pos);
kfree(pos);
}
write_unlock_bh(&nf_ct_gre_lock);
}
EXPORT_SYMBOL(nf_ct_gre_keymap_flush);
static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap *km,
const struct nf_conntrack_tuple *t)
{
return km->tuple.src.l3num == t->src.l3num &&
!memcmp(&km->tuple.src.u3, &t->src.u3, sizeof(t->src.u3)) &&
!memcmp(&km->tuple.dst.u3, &t->dst.u3, sizeof(t->dst.u3)) &&
km->tuple.dst.protonum == t->dst.protonum &&
km->tuple.dst.u.all == t->dst.u.all;
}
/* look up the source key for a given tuple */
static __be16 gre_keymap_lookup(struct nf_conntrack_tuple *t)
{
struct nf_ct_gre_keymap *km;
__be16 key = 0;
read_lock_bh(&nf_ct_gre_lock);
list_for_each_entry(km, &gre_keymap_list, list) {
if (gre_key_cmpfn(km, t)) {
key = km->tuple.src.u.gre.key;
break;
}
}
read_unlock_bh(&nf_ct_gre_lock);
DEBUGP("lookup src key 0x%x for ", key);
NF_CT_DUMP_TUPLE(t);
return key;
}
/* add a single keymap entry, associate with specified master ct */
int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
struct nf_conntrack_tuple *t)
{
struct nf_conn_help *help = nfct_help(ct);
struct nf_ct_gre_keymap **kmp, *km;
BUG_ON(strcmp(help->helper->name, "pptp"));
kmp = &help->help.ct_pptp_info.keymap[dir];
if (*kmp) {
/* check whether it's a retransmission */
list_for_each_entry(km, &gre_keymap_list, list) {
if (gre_key_cmpfn(km, t) && km == *kmp)
return 0;
}
DEBUGP("trying to override keymap_%s for ct %p\n",
dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct);
return -EEXIST;
}
km = kmalloc(sizeof(*km), GFP_ATOMIC);
if (!km)
return -ENOMEM;
memcpy(&km->tuple, t, sizeof(*t));
*kmp = km;
DEBUGP("adding new entry %p: ", km);
NF_CT_DUMP_TUPLE(&km->tuple);
write_lock_bh(&nf_ct_gre_lock);
list_add_tail(&km->list, &gre_keymap_list);
write_unlock_bh(&nf_ct_gre_lock);
return 0;
}
EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add);
/* destroy the keymap entries associated with specified master ct */
void nf_ct_gre_keymap_destroy(struct nf_conn *ct)
{
struct nf_conn_help *help = nfct_help(ct);
enum ip_conntrack_dir dir;
DEBUGP("entering for ct %p\n", ct);
BUG_ON(strcmp(help->helper->name, "pptp"));
write_lock_bh(&nf_ct_gre_lock);
for (dir = IP_CT_DIR_ORIGINAL; dir < IP_CT_DIR_MAX; dir++) {
if (help->help.ct_pptp_info.keymap[dir]) {
DEBUGP("removing %p from list\n",
help->help.ct_pptp_info.keymap[dir]);
list_del(&help->help.ct_pptp_info.keymap[dir]->list);
kfree(help->help.ct_pptp_info.keymap[dir]);
help->help.ct_pptp_info.keymap[dir] = NULL;
}
}
write_unlock_bh(&nf_ct_gre_lock);
}
EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy);
/* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
/* invert gre part of tuple */
static int gre_invert_tuple(struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_tuple *orig)
{
tuple->dst.u.gre.key = orig->src.u.gre.key;
tuple->src.u.gre.key = orig->dst.u.gre.key;
return 1;
}
/* gre hdr info to tuple */
static int gre_pkt_to_tuple(const struct sk_buff *skb,
unsigned int dataoff,
struct nf_conntrack_tuple *tuple)
{
struct gre_hdr_pptp _pgrehdr, *pgrehdr;
__be16 srckey;
struct gre_hdr _grehdr, *grehdr;
/* first only delinearize old RFC1701 GRE header */
grehdr = skb_header_pointer(skb, dataoff, sizeof(_grehdr), &_grehdr);
if (!grehdr || grehdr->version != GRE_VERSION_PPTP) {
/* try to behave like "nf_conntrack_proto_generic" */
tuple->src.u.all = 0;
tuple->dst.u.all = 0;
return 1;
}
/* PPTP header is variable length, only need up to the call_id field */
pgrehdr = skb_header_pointer(skb, dataoff, 8, &_pgrehdr);
if (!pgrehdr)
return 1;
if (ntohs(grehdr->protocol) != GRE_PROTOCOL_PPTP) {
DEBUGP("GRE_VERSION_PPTP but unknown proto\n");
return 0;
}
tuple->dst.u.gre.key = pgrehdr->call_id;
srckey = gre_keymap_lookup(tuple);
tuple->src.u.gre.key = srckey;
return 1;
}
/* print gre part of tuple */
static int gre_print_tuple(struct seq_file *s,
const struct nf_conntrack_tuple *tuple)
{
return seq_printf(s, "srckey=0x%x dstkey=0x%x ",
ntohs(tuple->src.u.gre.key),
ntohs(tuple->dst.u.gre.key));
}
/* print private data for conntrack */
static int gre_print_conntrack(struct seq_file *s,
const struct nf_conn *ct)
{
return seq_printf(s, "timeout=%u, stream_timeout=%u ",
(ct->proto.gre.timeout / HZ),
(ct->proto.gre.stream_timeout / HZ));
}
/* Returns verdict for packet, and may modify conntrack */
static int gre_packet(struct nf_conn *ct,
const struct sk_buff *skb,
unsigned int dataoff,
enum ip_conntrack_info ctinfo,
int pf,
unsigned int hooknum)
{
/* If we've seen traffic both ways, this is a GRE connection.
* Extend timeout. */
if (ct->status & IPS_SEEN_REPLY) {
nf_ct_refresh_acct(ct, ctinfo, skb,
ct->proto.gre.stream_timeout);
/* Also, more likely to be important, and not a probe. */
set_bit(IPS_ASSURED_BIT, &ct->status);
nf_conntrack_event_cache(IPCT_STATUS, skb);
} else
nf_ct_refresh_acct(ct, ctinfo, skb,
ct->proto.gre.timeout);
return NF_ACCEPT;
}
/* Called when a new connection for this protocol found. */
static int gre_new(struct nf_conn *ct, const struct sk_buff *skb,
unsigned int dataoff)
{
DEBUGP(": ");
NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
/* initialize to sane value. Ideally a conntrack helper
* (e.g. in case of pptp) is increasing them */
ct->proto.gre.stream_timeout = GRE_STREAM_TIMEOUT;
ct->proto.gre.timeout = GRE_TIMEOUT;
return 1;
}
/* Called when a conntrack entry has already been removed from the hashes
* and is about to be deleted from memory */
static void gre_destroy(struct nf_conn *ct)
{
struct nf_conn *master = ct->master;
DEBUGP(" entering\n");
if (!master)
DEBUGP("no master !?!\n");
else
nf_ct_gre_keymap_destroy(master);
}
/* protocol helper struct */
static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 = {
.l3proto = AF_INET,
.l4proto = IPPROTO_GRE,
.name = "gre",
.pkt_to_tuple = gre_pkt_to_tuple,
.invert_tuple = gre_invert_tuple,
.print_tuple = gre_print_tuple,
.print_conntrack = gre_print_conntrack,
.packet = gre_packet,
.new = gre_new,
.destroy = gre_destroy,
.me = THIS_MODULE,
#if defined(CONFIG_NF_CONNTRACK_NETLINK) || \
defined(CONFIG_NF_CONNTRACK_NETLINK_MODULE)
.tuple_to_nfattr = nf_ct_port_tuple_to_nfattr,
.nfattr_to_tuple = nf_ct_port_nfattr_to_tuple,
#endif
};
static int __init nf_ct_proto_gre_init(void)
{
return nf_conntrack_l4proto_register(&nf_conntrack_l4proto_gre4);
}
static void nf_ct_proto_gre_fini(void)
{
nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4);
nf_ct_gre_keymap_flush();
}
module_init(nf_ct_proto_gre_init);
module_exit(nf_ct_proto_gre_fini);
MODULE_LICENSE("GPL");