1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Connection tracking support for PPTP (Point to Point Tunneling Protocol).
4 * PPTP is a protocol for creating virtual private networks.
5 * It is a specification defined by Microsoft and some vendors
6 * working with Microsoft. PPTP is built on top of a modified
7 * version of the Internet Generic Routing Encapsulation Protocol.
8 * GRE is defined in RFC 1701 and RFC 1702. Documentation of
9 * PPTP can be found in RFC 2637
10 *
11 * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
12 *
13 * Development of this code funded by Astaro AG (http://www.astaro.com/)
14 *
15 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
16 *
17 * Limitations:
18 * - We blindly assume that control connections are always
19 * established in PNS->PAC direction. This is a violation
20 * of RFC 2637
21 * - We can only support one single call within each session
22 * TODO:
23 * - testing of incoming PPTP calls
24 */
25
26 #include <linux/module.h>
27 #include <linux/skbuff.h>
28 #include <linux/in.h>
29 #include <linux/tcp.h>
30
31 #include <net/netfilter/nf_conntrack.h>
32 #include <net/netfilter/nf_conntrack_core.h>
33 #include <net/netfilter/nf_conntrack_helper.h>
34 #include <net/netfilter/nf_conntrack_zones.h>
35 #include <linux/netfilter/nf_conntrack_proto_gre.h>
36 #include <linux/netfilter/nf_conntrack_pptp.h>
37
38 #define NF_CT_PPTP_VERSION "3.1"
39
40 MODULE_LICENSE("GPL");
41 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
42 MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP");
43 MODULE_ALIAS("ip_conntrack_pptp");
44 MODULE_ALIAS_NFCT_HELPER("pptp");
45
46 static DEFINE_SPINLOCK(nf_pptp_lock);
47
48 const struct nf_nat_pptp_hook __rcu *nf_nat_pptp_hook;
49 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook);
50
51 #if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
52 /* PptpControlMessageType names */
53 static const char *const pptp_msg_name_array[PPTP_MSG_MAX + 1] = {
54 [0] = "UNKNOWN_MESSAGE",
55 [PPTP_START_SESSION_REQUEST] = "START_SESSION_REQUEST",
56 [PPTP_START_SESSION_REPLY] = "START_SESSION_REPLY",
57 [PPTP_STOP_SESSION_REQUEST] = "STOP_SESSION_REQUEST",
58 [PPTP_STOP_SESSION_REPLY] = "STOP_SESSION_REPLY",
59 [PPTP_ECHO_REQUEST] = "ECHO_REQUEST",
60 [PPTP_ECHO_REPLY] = "ECHO_REPLY",
61 [PPTP_OUT_CALL_REQUEST] = "OUT_CALL_REQUEST",
62 [PPTP_OUT_CALL_REPLY] = "OUT_CALL_REPLY",
63 [PPTP_IN_CALL_REQUEST] = "IN_CALL_REQUEST",
64 [PPTP_IN_CALL_REPLY] = "IN_CALL_REPLY",
65 [PPTP_IN_CALL_CONNECT] = "IN_CALL_CONNECT",
66 [PPTP_CALL_CLEAR_REQUEST] = "CALL_CLEAR_REQUEST",
67 [PPTP_CALL_DISCONNECT_NOTIFY] = "CALL_DISCONNECT_NOTIFY",
68 [PPTP_WAN_ERROR_NOTIFY] = "WAN_ERROR_NOTIFY",
69 [PPTP_SET_LINK_INFO] = "SET_LINK_INFO"
70 };
71
pptp_msg_name(u_int16_t msg)72 const char *pptp_msg_name(u_int16_t msg)
73 {
74 if (msg > PPTP_MSG_MAX)
75 return pptp_msg_name_array[0];
76
77 return pptp_msg_name_array[msg];
78 }
79 EXPORT_SYMBOL(pptp_msg_name);
80 #endif
81
82 #define SECS *HZ
83 #define MINS * 60 SECS
84 #define HOURS * 60 MINS
85
86 #define PPTP_GRE_TIMEOUT (10 MINS)
87 #define PPTP_GRE_STREAM_TIMEOUT (5 HOURS)
88
pptp_expectfn(struct nf_conn * ct,struct nf_conntrack_expect * exp)89 static void pptp_expectfn(struct nf_conn *ct,
90 struct nf_conntrack_expect *exp)
91 {
92 const struct nf_nat_pptp_hook *hook;
93 struct net *net = nf_ct_net(ct);
94 pr_debug("increasing timeouts\n");
95
96 /* increase timeout of GRE data channel conntrack entry */
97 ct->proto.gre.timeout = PPTP_GRE_TIMEOUT;
98 ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT;
99
100 /* Can you see how rusty this code is, compared with the pre-2.6.11
101 * one? That's what happened to my shiny newnat of 2002 ;( -HW */
102
103 hook = rcu_dereference(nf_nat_pptp_hook);
104 if (hook && ct->master->status & IPS_NAT_MASK)
105 hook->expectfn(ct, exp);
106 else {
107 struct nf_conntrack_tuple inv_t;
108 struct nf_conntrack_expect *exp_other;
109
110 /* obviously this tuple inversion only works until you do NAT */
111 nf_ct_invert_tuple(&inv_t, &exp->tuple);
112 pr_debug("trying to unexpect other dir: ");
113 nf_ct_dump_tuple(&inv_t);
114
115 exp_other = nf_ct_expect_find_get(net, nf_ct_zone(ct), &inv_t);
116 if (exp_other) {
117 /* delete other expectation. */
118 pr_debug("found\n");
119 nf_ct_unexpect_related(exp_other);
120 nf_ct_expect_put(exp_other);
121 } else {
122 pr_debug("not found\n");
123 }
124 }
125 }
126
127 /* expect GRE connections (PNS->PAC and PAC->PNS direction) */
exp_gre(struct nf_conn * ct,__be16 callid,__be16 peer_callid)128 static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid)
129 {
130 struct nf_conntrack_expect *exp_orig, *exp_reply;
131 const struct nf_nat_pptp_hook *hook;
132 enum ip_conntrack_dir dir;
133 int ret = 1;
134
135 exp_orig = nf_ct_expect_alloc(ct);
136 if (exp_orig == NULL)
137 goto out;
138
139 exp_reply = nf_ct_expect_alloc(ct);
140 if (exp_reply == NULL)
141 goto out_put_orig;
142
143 /* original direction, PNS->PAC */
144 dir = IP_CT_DIR_ORIGINAL;
145 nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT,
146 nf_ct_l3num(ct),
147 &ct->tuplehash[dir].tuple.src.u3,
148 &ct->tuplehash[dir].tuple.dst.u3,
149 IPPROTO_GRE, &peer_callid, &callid);
150 exp_orig->expectfn = pptp_expectfn;
151
152 /* reply direction, PAC->PNS */
153 dir = IP_CT_DIR_REPLY;
154 nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT,
155 nf_ct_l3num(ct),
156 &ct->tuplehash[dir].tuple.src.u3,
157 &ct->tuplehash[dir].tuple.dst.u3,
158 IPPROTO_GRE, &callid, &peer_callid);
159 exp_reply->expectfn = pptp_expectfn;
160
161 hook = rcu_dereference(nf_nat_pptp_hook);
162 if (hook && ct->status & IPS_NAT_MASK)
163 hook->exp_gre(exp_orig, exp_reply);
164 if (nf_ct_expect_related(exp_orig, 0) != 0)
165 goto out_put_both;
166 if (nf_ct_expect_related(exp_reply, 0) != 0)
167 goto out_unexpect_orig;
168
169 if (!nf_ct_gre_keymap_add(ct, &exp_orig->tuple,
170 &exp_reply->tuple))
171 goto out_unexpect_both;
172 ret = 0;
173
174 out_put_both:
175 nf_ct_expect_put(exp_reply);
176 out_put_orig:
177 nf_ct_expect_put(exp_orig);
178 out:
179 return ret;
180
181 out_unexpect_both:
182 nf_ct_unexpect_related(exp_reply);
183 out_unexpect_orig:
184 nf_ct_unexpect_related(exp_orig);
185 goto out_put_both;
186 }
187
188 static int
pptp_inbound_pkt(struct sk_buff * skb,unsigned int protoff,struct PptpControlHeader * ctlh,union pptp_ctrl_union * pptpReq,unsigned int reqlen,struct nf_conn * ct,enum ip_conntrack_info ctinfo)189 pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff,
190 struct PptpControlHeader *ctlh,
191 union pptp_ctrl_union *pptpReq,
192 unsigned int reqlen,
193 struct nf_conn *ct,
194 enum ip_conntrack_info ctinfo)
195 {
196 struct nf_ct_pptp_master *info = nfct_help_data(ct);
197 const struct nf_nat_pptp_hook *hook;
198 u_int16_t msg;
199 __be16 cid = 0, pcid = 0;
200
201 if (!info)
202 return NF_DROP;
203
204 msg = ntohs(ctlh->messageType);
205 pr_debug("inbound control message %s\n", pptp_msg_name(msg));
206
207 switch (msg) {
208 case PPTP_START_SESSION_REPLY:
209 /* server confirms new control session */
210 if (info->sstate < PPTP_SESSION_REQUESTED)
211 goto invalid;
212 if (pptpReq->srep.resultCode == PPTP_START_OK)
213 info->sstate = PPTP_SESSION_CONFIRMED;
214 else
215 info->sstate = PPTP_SESSION_ERROR;
216 break;
217
218 case PPTP_STOP_SESSION_REPLY:
219 /* server confirms end of control session */
220 if (info->sstate > PPTP_SESSION_STOPREQ)
221 goto invalid;
222 if (pptpReq->strep.resultCode == PPTP_STOP_OK)
223 info->sstate = PPTP_SESSION_NONE;
224 else
225 info->sstate = PPTP_SESSION_ERROR;
226 break;
227
228 case PPTP_OUT_CALL_REPLY:
229 /* server accepted call, we now expect GRE frames */
230 if (info->sstate != PPTP_SESSION_CONFIRMED)
231 goto invalid;
232 if (info->cstate != PPTP_CALL_OUT_REQ &&
233 info->cstate != PPTP_CALL_OUT_CONF)
234 goto invalid;
235
236 cid = pptpReq->ocack.callID;
237 pcid = pptpReq->ocack.peersCallID;
238 if (info->pns_call_id != pcid)
239 goto invalid;
240 pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name(msg),
241 ntohs(cid), ntohs(pcid));
242
243 if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) {
244 info->cstate = PPTP_CALL_OUT_CONF;
245 info->pac_call_id = cid;
246 exp_gre(ct, cid, pcid);
247 } else
248 info->cstate = PPTP_CALL_NONE;
249 break;
250
251 case PPTP_IN_CALL_REQUEST:
252 /* server tells us about incoming call request */
253 if (info->sstate != PPTP_SESSION_CONFIRMED)
254 goto invalid;
255
256 cid = pptpReq->icreq.callID;
257 pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));
258 info->cstate = PPTP_CALL_IN_REQ;
259 info->pac_call_id = cid;
260 break;
261
262 case PPTP_IN_CALL_CONNECT:
263 /* server tells us about incoming call established */
264 if (info->sstate != PPTP_SESSION_CONFIRMED)
265 goto invalid;
266 if (info->cstate != PPTP_CALL_IN_REP &&
267 info->cstate != PPTP_CALL_IN_CONF)
268 goto invalid;
269
270 pcid = pptpReq->iccon.peersCallID;
271 cid = info->pac_call_id;
272
273 if (info->pns_call_id != pcid)
274 goto invalid;
275
276 pr_debug("%s, PCID=%X\n", pptp_msg_name(msg), ntohs(pcid));
277 info->cstate = PPTP_CALL_IN_CONF;
278
279 /* we expect a GRE connection from PAC to PNS */
280 exp_gre(ct, cid, pcid);
281 break;
282
283 case PPTP_CALL_DISCONNECT_NOTIFY:
284 /* server confirms disconnect */
285 cid = pptpReq->disc.callID;
286 pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));
287 info->cstate = PPTP_CALL_NONE;
288
289 /* untrack this call id, unexpect GRE packets */
290 gre_pptp_destroy_siblings(ct);
291 break;
292
293 case PPTP_WAN_ERROR_NOTIFY:
294 case PPTP_SET_LINK_INFO:
295 case PPTP_ECHO_REQUEST:
296 case PPTP_ECHO_REPLY:
297 /* I don't have to explain these ;) */
298 break;
299
300 default:
301 goto invalid;
302 }
303
304 hook = rcu_dereference(nf_nat_pptp_hook);
305 if (hook && ct->status & IPS_NAT_MASK)
306 return hook->inbound(skb, ct, ctinfo, protoff, ctlh, pptpReq);
307 return NF_ACCEPT;
308
309 invalid:
310 pr_debug("invalid %s: type=%d cid=%u pcid=%u "
311 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
312 pptp_msg_name(msg),
313 msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
314 ntohs(info->pns_call_id), ntohs(info->pac_call_id));
315 return NF_ACCEPT;
316 }
317
318 static int
pptp_outbound_pkt(struct sk_buff * skb,unsigned int protoff,struct PptpControlHeader * ctlh,union pptp_ctrl_union * pptpReq,unsigned int reqlen,struct nf_conn * ct,enum ip_conntrack_info ctinfo)319 pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff,
320 struct PptpControlHeader *ctlh,
321 union pptp_ctrl_union *pptpReq,
322 unsigned int reqlen,
323 struct nf_conn *ct,
324 enum ip_conntrack_info ctinfo)
325 {
326 struct nf_ct_pptp_master *info = nfct_help_data(ct);
327 const struct nf_nat_pptp_hook *hook;
328 u_int16_t msg;
329 __be16 cid = 0, pcid = 0;
330
331 if (!info)
332 return NF_DROP;
333
334 msg = ntohs(ctlh->messageType);
335 pr_debug("outbound control message %s\n", pptp_msg_name(msg));
336
337 switch (msg) {
338 case PPTP_START_SESSION_REQUEST:
339 /* client requests for new control session */
340 if (info->sstate != PPTP_SESSION_NONE)
341 goto invalid;
342 info->sstate = PPTP_SESSION_REQUESTED;
343 break;
344
345 case PPTP_STOP_SESSION_REQUEST:
346 /* client requests end of control session */
347 info->sstate = PPTP_SESSION_STOPREQ;
348 break;
349
350 case PPTP_OUT_CALL_REQUEST:
351 /* client initiating connection to server */
352 if (info->sstate != PPTP_SESSION_CONFIRMED)
353 goto invalid;
354 info->cstate = PPTP_CALL_OUT_REQ;
355 /* track PNS call id */
356 cid = pptpReq->ocreq.callID;
357 pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));
358 info->pns_call_id = cid;
359 break;
360
361 case PPTP_IN_CALL_REPLY:
362 /* client answers incoming call */
363 if (info->cstate != PPTP_CALL_IN_REQ &&
364 info->cstate != PPTP_CALL_IN_REP)
365 goto invalid;
366
367 cid = pptpReq->icack.callID;
368 pcid = pptpReq->icack.peersCallID;
369 if (info->pac_call_id != pcid)
370 goto invalid;
371 pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name(msg),
372 ntohs(cid), ntohs(pcid));
373
374 if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
375 /* part two of the three-way handshake */
376 info->cstate = PPTP_CALL_IN_REP;
377 info->pns_call_id = cid;
378 } else
379 info->cstate = PPTP_CALL_NONE;
380 break;
381
382 case PPTP_CALL_CLEAR_REQUEST:
383 /* client requests hangup of call */
384 if (info->sstate != PPTP_SESSION_CONFIRMED)
385 goto invalid;
386 /* FUTURE: iterate over all calls and check if
387 * call ID is valid. We don't do this without newnat,
388 * because we only know about last call */
389 info->cstate = PPTP_CALL_CLEAR_REQ;
390 break;
391
392 case PPTP_SET_LINK_INFO:
393 case PPTP_ECHO_REQUEST:
394 case PPTP_ECHO_REPLY:
395 /* I don't have to explain these ;) */
396 break;
397
398 default:
399 goto invalid;
400 }
401
402 hook = rcu_dereference(nf_nat_pptp_hook);
403 if (hook && ct->status & IPS_NAT_MASK)
404 return hook->outbound(skb, ct, ctinfo, protoff, ctlh, pptpReq);
405 return NF_ACCEPT;
406
407 invalid:
408 pr_debug("invalid %s: type=%d cid=%u pcid=%u "
409 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
410 pptp_msg_name(msg),
411 msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
412 ntohs(info->pns_call_id), ntohs(info->pac_call_id));
413 return NF_ACCEPT;
414 }
415
416 static const unsigned int pptp_msg_size[] = {
417 [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest),
418 [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply),
419 [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest),
420 [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply),
421 [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest),
422 [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply),
423 [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest),
424 [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply),
425 [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected),
426 [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest),
427 [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
428 [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify),
429 [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo),
430 };
431
432 /* track caller id inside control connection, call expect_related */
433 static int
conntrack_pptp_help(struct sk_buff * skb,unsigned int protoff,struct nf_conn * ct,enum ip_conntrack_info ctinfo)434 conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff,
435 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
436
437 {
438 int dir = CTINFO2DIR(ctinfo);
439 const struct nf_ct_pptp_master *info = nfct_help_data(ct);
440 const struct tcphdr *tcph;
441 struct tcphdr _tcph;
442 const struct pptp_pkt_hdr *pptph;
443 struct pptp_pkt_hdr _pptph;
444 struct PptpControlHeader _ctlh, *ctlh;
445 union pptp_ctrl_union _pptpReq, *pptpReq;
446 unsigned int tcplen = skb->len - protoff;
447 unsigned int datalen, reqlen, nexthdr_off;
448 int oldsstate, oldcstate;
449 int ret;
450 u_int16_t msg;
451
452 if (!info)
453 return NF_DROP;
454
455 #if IS_ENABLED(CONFIG_NF_NAT)
456 if (!nf_ct_is_confirmed(ct) && (ct->status & IPS_NAT_MASK)) {
457 struct nf_conn_nat *nat = nf_ct_ext_find(ct, NF_CT_EXT_NAT);
458
459 if (!nat && !nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC))
460 return NF_DROP;
461 }
462 #endif
463 /* don't do any tracking before tcp handshake complete */
464 if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
465 return NF_ACCEPT;
466
467 nexthdr_off = protoff;
468 tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph);
469 if (!tcph)
470 return NF_ACCEPT;
471
472 nexthdr_off += tcph->doff * 4;
473 datalen = tcplen - tcph->doff * 4;
474
475 pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph);
476 if (!pptph) {
477 pr_debug("no full PPTP header, can't track\n");
478 return NF_ACCEPT;
479 }
480 nexthdr_off += sizeof(_pptph);
481 datalen -= sizeof(_pptph);
482
483 /* if it's not a control message we can't do anything with it */
484 if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL ||
485 ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) {
486 pr_debug("not a control packet\n");
487 return NF_ACCEPT;
488 }
489
490 ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh);
491 if (!ctlh)
492 return NF_ACCEPT;
493 nexthdr_off += sizeof(_ctlh);
494 datalen -= sizeof(_ctlh);
495
496 reqlen = datalen;
497 msg = ntohs(ctlh->messageType);
498 if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
499 return NF_ACCEPT;
500 if (reqlen > sizeof(*pptpReq))
501 reqlen = sizeof(*pptpReq);
502
503 pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq);
504 if (!pptpReq)
505 return NF_ACCEPT;
506
507 oldsstate = info->sstate;
508 oldcstate = info->cstate;
509
510 spin_lock_bh(&nf_pptp_lock);
511
512 /* FIXME: We just blindly assume that the control connection is always
513 * established from PNS->PAC. However, RFC makes no guarantee */
514 if (dir == IP_CT_DIR_ORIGINAL)
515 /* client -> server (PNS -> PAC) */
516 ret = pptp_outbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct,
517 ctinfo);
518 else
519 /* server -> client (PAC -> PNS) */
520 ret = pptp_inbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct,
521 ctinfo);
522 pr_debug("sstate: %d->%d, cstate: %d->%d\n",
523 oldsstate, info->sstate, oldcstate, info->cstate);
524 spin_unlock_bh(&nf_pptp_lock);
525
526 return ret;
527 }
528
529 static const struct nf_conntrack_expect_policy pptp_exp_policy = {
530 .max_expected = 2,
531 .timeout = 5 * 60,
532 };
533
534 /* control protocol helper */
535 static struct nf_conntrack_helper pptp __read_mostly;
536 static struct nf_conntrack_helper *pptp_ptr __read_mostly;
537
nf_conntrack_pptp_init(void)538 static int __init nf_conntrack_pptp_init(void)
539 {
540 NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_pptp_master));
541
542 nf_ct_helper_init(&pptp, AF_INET, IPPROTO_TCP,
543 "pptp",
544 &pptp_exp_policy, 0, conntrack_pptp_help, NULL, THIS_MODULE);
545
546 pptp.destroy = gre_pptp_destroy_siblings;
547
548 nf_conntrack_helper_deprecated(pptp.name);
549
550 return nf_conntrack_helper_register(&pptp, &pptp_ptr);
551 }
552
nf_conntrack_pptp_fini(void)553 static void __exit nf_conntrack_pptp_fini(void)
554 {
555 nf_conntrack_helper_unregister(pptp_ptr);
556 }
557
558 module_init(nf_conntrack_pptp_init);
559 module_exit(nf_conntrack_pptp_fini);
560