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23#include <linux/module.h>
24#include <linux/skbuff.h>
25#include <linux/in.h>
26#include <linux/tcp.h>
27
28#include <net/netfilter/nf_conntrack.h>
29#include <net/netfilter/nf_conntrack_core.h>
30#include <net/netfilter/nf_conntrack_helper.h>
31#include <net/netfilter/nf_conntrack_zones.h>
32#include <linux/netfilter/nf_conntrack_proto_gre.h>
33#include <linux/netfilter/nf_conntrack_pptp.h>
34
35#define NF_CT_PPTP_VERSION "3.1"
36
37MODULE_LICENSE("GPL");
38MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
39MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP");
40MODULE_ALIAS("ip_conntrack_pptp");
41MODULE_ALIAS_NFCT_HELPER("pptp");
42
43static DEFINE_SPINLOCK(nf_pptp_lock);
44
45int
46(*nf_nat_pptp_hook_outbound)(struct sk_buff *skb,
47 struct nf_conn *ct, enum ip_conntrack_info ctinfo,
48 struct PptpControlHeader *ctlh,
49 union pptp_ctrl_union *pptpReq) __read_mostly;
50EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_outbound);
51
52int
53(*nf_nat_pptp_hook_inbound)(struct sk_buff *skb,
54 struct nf_conn *ct, enum ip_conntrack_info ctinfo,
55 struct PptpControlHeader *ctlh,
56 union pptp_ctrl_union *pptpReq) __read_mostly;
57EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_inbound);
58
59void
60(*nf_nat_pptp_hook_exp_gre)(struct nf_conntrack_expect *expect_orig,
61 struct nf_conntrack_expect *expect_reply)
62 __read_mostly;
63EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_exp_gre);
64
65void
66(*nf_nat_pptp_hook_expectfn)(struct nf_conn *ct,
67 struct nf_conntrack_expect *exp) __read_mostly;
68EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn);
69
70#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
71
72const char *const pptp_msg_name[] = {
73 "UNKNOWN_MESSAGE",
74 "START_SESSION_REQUEST",
75 "START_SESSION_REPLY",
76 "STOP_SESSION_REQUEST",
77 "STOP_SESSION_REPLY",
78 "ECHO_REQUEST",
79 "ECHO_REPLY",
80 "OUT_CALL_REQUEST",
81 "OUT_CALL_REPLY",
82 "IN_CALL_REQUEST",
83 "IN_CALL_REPLY",
84 "IN_CALL_CONNECT",
85 "CALL_CLEAR_REQUEST",
86 "CALL_DISCONNECT_NOTIFY",
87 "WAN_ERROR_NOTIFY",
88 "SET_LINK_INFO"
89};
90EXPORT_SYMBOL(pptp_msg_name);
91#endif
92
93#define SECS *HZ
94#define MINS * 60 SECS
95#define HOURS * 60 MINS
96
97#define PPTP_GRE_TIMEOUT (10 MINS)
98#define PPTP_GRE_STREAM_TIMEOUT (5 HOURS)
99
100static void pptp_expectfn(struct nf_conn *ct,
101 struct nf_conntrack_expect *exp)
102{
103 struct net *net = nf_ct_net(ct);
104 typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn;
105 pr_debug("increasing timeouts\n");
106
107
108 ct->proto.gre.timeout = PPTP_GRE_TIMEOUT;
109 ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT;
110
111
112
113
114 rcu_read_lock();
115 nf_nat_pptp_expectfn = rcu_dereference(nf_nat_pptp_hook_expectfn);
116 if (nf_nat_pptp_expectfn && ct->master->status & IPS_NAT_MASK)
117 nf_nat_pptp_expectfn(ct, exp);
118 else {
119 struct nf_conntrack_tuple inv_t;
120 struct nf_conntrack_expect *exp_other;
121
122
123 nf_ct_invert_tuplepr(&inv_t, &exp->tuple);
124 pr_debug("trying to unexpect other dir: ");
125 nf_ct_dump_tuple(&inv_t);
126
127 exp_other = nf_ct_expect_find_get(net, nf_ct_zone(ct), &inv_t);
128 if (exp_other) {
129
130 pr_debug("found\n");
131 nf_ct_unexpect_related(exp_other);
132 nf_ct_expect_put(exp_other);
133 } else {
134 pr_debug("not found\n");
135 }
136 }
137 rcu_read_unlock();
138}
139
140static int destroy_sibling_or_exp(struct net *net, struct nf_conn *ct,
141 const struct nf_conntrack_tuple *t)
142{
143 const struct nf_conntrack_tuple_hash *h;
144 struct nf_conntrack_expect *exp;
145 struct nf_conn *sibling;
146 u16 zone = nf_ct_zone(ct);
147
148 pr_debug("trying to timeout ct or exp for tuple ");
149 nf_ct_dump_tuple(t);
150
151 h = nf_conntrack_find_get(net, zone, t);
152 if (h) {
153 sibling = nf_ct_tuplehash_to_ctrack(h);
154 pr_debug("setting timeout of conntrack %p to 0\n", sibling);
155 sibling->proto.gre.timeout = 0;
156 sibling->proto.gre.stream_timeout = 0;
157 if (del_timer(&sibling->timeout))
158 sibling->timeout.function((unsigned long)sibling);
159 nf_ct_put(sibling);
160 return 1;
161 } else {
162 exp = nf_ct_expect_find_get(net, zone, t);
163 if (exp) {
164 pr_debug("unexpect_related of expect %p\n", exp);
165 nf_ct_unexpect_related(exp);
166 nf_ct_expect_put(exp);
167 return 1;
168 }
169 }
170 return 0;
171}
172
173
174static void pptp_destroy_siblings(struct nf_conn *ct)
175{
176 struct net *net = nf_ct_net(ct);
177 const struct nf_conn_help *help = nfct_help(ct);
178 struct nf_conntrack_tuple t;
179
180 nf_ct_gre_keymap_destroy(ct);
181
182
183 memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t));
184 t.dst.protonum = IPPROTO_GRE;
185 t.src.u.gre.key = help->help.ct_pptp_info.pns_call_id;
186 t.dst.u.gre.key = help->help.ct_pptp_info.pac_call_id;
187 if (!destroy_sibling_or_exp(net, ct, &t))
188 pr_debug("failed to timeout original pns->pac ct/exp\n");
189
190
191 memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t));
192 t.dst.protonum = IPPROTO_GRE;
193 t.src.u.gre.key = help->help.ct_pptp_info.pac_call_id;
194 t.dst.u.gre.key = help->help.ct_pptp_info.pns_call_id;
195 if (!destroy_sibling_or_exp(net, ct, &t))
196 pr_debug("failed to timeout reply pac->pns ct/exp\n");
197}
198
199
200static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid)
201{
202 struct nf_conntrack_expect *exp_orig, *exp_reply;
203 enum ip_conntrack_dir dir;
204 int ret = 1;
205 typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre;
206
207 exp_orig = nf_ct_expect_alloc(ct);
208 if (exp_orig == NULL)
209 goto out;
210
211 exp_reply = nf_ct_expect_alloc(ct);
212 if (exp_reply == NULL)
213 goto out_put_orig;
214
215
216 dir = IP_CT_DIR_ORIGINAL;
217 nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT,
218 nf_ct_l3num(ct),
219 &ct->tuplehash[dir].tuple.src.u3,
220 &ct->tuplehash[dir].tuple.dst.u3,
221 IPPROTO_GRE, &peer_callid, &callid);
222 exp_orig->expectfn = pptp_expectfn;
223
224
225 dir = IP_CT_DIR_REPLY;
226 nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT,
227 nf_ct_l3num(ct),
228 &ct->tuplehash[dir].tuple.src.u3,
229 &ct->tuplehash[dir].tuple.dst.u3,
230 IPPROTO_GRE, &callid, &peer_callid);
231 exp_reply->expectfn = pptp_expectfn;
232
233 nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre);
234 if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK)
235 nf_nat_pptp_exp_gre(exp_orig, exp_reply);
236 if (nf_ct_expect_related(exp_orig) != 0)
237 goto out_put_both;
238 if (nf_ct_expect_related(exp_reply) != 0)
239 goto out_unexpect_orig;
240
241
242 if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0)
243 goto out_unexpect_both;
244 if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) {
245 nf_ct_gre_keymap_destroy(ct);
246 goto out_unexpect_both;
247 }
248 ret = 0;
249
250out_put_both:
251 nf_ct_expect_put(exp_reply);
252out_put_orig:
253 nf_ct_expect_put(exp_orig);
254out:
255 return ret;
256
257out_unexpect_both:
258 nf_ct_unexpect_related(exp_reply);
259out_unexpect_orig:
260 nf_ct_unexpect_related(exp_orig);
261 goto out_put_both;
262}
263
264static inline int
265pptp_inbound_pkt(struct sk_buff *skb,
266 struct PptpControlHeader *ctlh,
267 union pptp_ctrl_union *pptpReq,
268 unsigned int reqlen,
269 struct nf_conn *ct,
270 enum ip_conntrack_info ctinfo)
271{
272 struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info;
273 u_int16_t msg;
274 __be16 cid = 0, pcid = 0;
275 typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound;
276
277 msg = ntohs(ctlh->messageType);
278 pr_debug("inbound control message %s\n", pptp_msg_name[msg]);
279
280 switch (msg) {
281 case PPTP_START_SESSION_REPLY:
282
283 if (info->sstate < PPTP_SESSION_REQUESTED)
284 goto invalid;
285 if (pptpReq->srep.resultCode == PPTP_START_OK)
286 info->sstate = PPTP_SESSION_CONFIRMED;
287 else
288 info->sstate = PPTP_SESSION_ERROR;
289 break;
290
291 case PPTP_STOP_SESSION_REPLY:
292
293 if (info->sstate > PPTP_SESSION_STOPREQ)
294 goto invalid;
295 if (pptpReq->strep.resultCode == PPTP_STOP_OK)
296 info->sstate = PPTP_SESSION_NONE;
297 else
298 info->sstate = PPTP_SESSION_ERROR;
299 break;
300
301 case PPTP_OUT_CALL_REPLY:
302
303 if (info->sstate != PPTP_SESSION_CONFIRMED)
304 goto invalid;
305 if (info->cstate != PPTP_CALL_OUT_REQ &&
306 info->cstate != PPTP_CALL_OUT_CONF)
307 goto invalid;
308
309 cid = pptpReq->ocack.callID;
310 pcid = pptpReq->ocack.peersCallID;
311 if (info->pns_call_id != pcid)
312 goto invalid;
313 pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg],
314 ntohs(cid), ntohs(pcid));
315
316 if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) {
317 info->cstate = PPTP_CALL_OUT_CONF;
318 info->pac_call_id = cid;
319 exp_gre(ct, cid, pcid);
320 } else
321 info->cstate = PPTP_CALL_NONE;
322 break;
323
324 case PPTP_IN_CALL_REQUEST:
325
326 if (info->sstate != PPTP_SESSION_CONFIRMED)
327 goto invalid;
328
329 cid = pptpReq->icreq.callID;
330 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
331 info->cstate = PPTP_CALL_IN_REQ;
332 info->pac_call_id = cid;
333 break;
334
335 case PPTP_IN_CALL_CONNECT:
336
337 if (info->sstate != PPTP_SESSION_CONFIRMED)
338 goto invalid;
339 if (info->cstate != PPTP_CALL_IN_REP &&
340 info->cstate != PPTP_CALL_IN_CONF)
341 goto invalid;
342
343 pcid = pptpReq->iccon.peersCallID;
344 cid = info->pac_call_id;
345
346 if (info->pns_call_id != pcid)
347 goto invalid;
348
349 pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid));
350 info->cstate = PPTP_CALL_IN_CONF;
351
352
353 exp_gre(ct, cid, pcid);
354 break;
355
356 case PPTP_CALL_DISCONNECT_NOTIFY:
357
358 cid = pptpReq->disc.callID;
359 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
360 info->cstate = PPTP_CALL_NONE;
361
362
363 pptp_destroy_siblings(ct);
364 break;
365
366 case PPTP_WAN_ERROR_NOTIFY:
367 case PPTP_ECHO_REQUEST:
368 case PPTP_ECHO_REPLY:
369
370 break;
371
372 default:
373 goto invalid;
374 }
375
376 nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound);
377 if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK)
378 return nf_nat_pptp_inbound(skb, ct, ctinfo, ctlh, pptpReq);
379 return NF_ACCEPT;
380
381invalid:
382 pr_debug("invalid %s: type=%d cid=%u pcid=%u "
383 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
384 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
385 msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
386 ntohs(info->pns_call_id), ntohs(info->pac_call_id));
387 return NF_ACCEPT;
388}
389
390static inline int
391pptp_outbound_pkt(struct sk_buff *skb,
392 struct PptpControlHeader *ctlh,
393 union pptp_ctrl_union *pptpReq,
394 unsigned int reqlen,
395 struct nf_conn *ct,
396 enum ip_conntrack_info ctinfo)
397{
398 struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info;
399 u_int16_t msg;
400 __be16 cid = 0, pcid = 0;
401 typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound;
402
403 msg = ntohs(ctlh->messageType);
404 pr_debug("outbound control message %s\n", pptp_msg_name[msg]);
405
406 switch (msg) {
407 case PPTP_START_SESSION_REQUEST:
408
409 if (info->sstate != PPTP_SESSION_NONE)
410 goto invalid;
411 info->sstate = PPTP_SESSION_REQUESTED;
412 break;
413
414 case PPTP_STOP_SESSION_REQUEST:
415
416 info->sstate = PPTP_SESSION_STOPREQ;
417 break;
418
419 case PPTP_OUT_CALL_REQUEST:
420
421 if (info->sstate != PPTP_SESSION_CONFIRMED)
422 goto invalid;
423 info->cstate = PPTP_CALL_OUT_REQ;
424
425 cid = pptpReq->ocreq.callID;
426 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
427 info->pns_call_id = cid;
428 break;
429
430 case PPTP_IN_CALL_REPLY:
431
432 if (info->cstate != PPTP_CALL_IN_REQ &&
433 info->cstate != PPTP_CALL_IN_REP)
434 goto invalid;
435
436 cid = pptpReq->icack.callID;
437 pcid = pptpReq->icack.peersCallID;
438 if (info->pac_call_id != pcid)
439 goto invalid;
440 pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg],
441 ntohs(cid), ntohs(pcid));
442
443 if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
444
445 info->cstate = PPTP_CALL_IN_REP;
446 info->pns_call_id = cid;
447 } else
448 info->cstate = PPTP_CALL_NONE;
449 break;
450
451 case PPTP_CALL_CLEAR_REQUEST:
452
453 if (info->sstate != PPTP_SESSION_CONFIRMED)
454 goto invalid;
455
456
457
458 info->cstate = PPTP_CALL_CLEAR_REQ;
459 break;
460
461 case PPTP_SET_LINK_INFO:
462 case PPTP_ECHO_REQUEST:
463 case PPTP_ECHO_REPLY:
464
465 break;
466
467 default:
468 goto invalid;
469 }
470
471 nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound);
472 if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK)
473 return nf_nat_pptp_outbound(skb, ct, ctinfo, ctlh, pptpReq);
474 return NF_ACCEPT;
475
476invalid:
477 pr_debug("invalid %s: type=%d cid=%u pcid=%u "
478 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
479 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
480 msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
481 ntohs(info->pns_call_id), ntohs(info->pac_call_id));
482 return NF_ACCEPT;
483}
484
485static const unsigned int pptp_msg_size[] = {
486 [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest),
487 [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply),
488 [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest),
489 [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply),
490 [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest),
491 [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply),
492 [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest),
493 [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply),
494 [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected),
495 [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest),
496 [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
497 [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify),
498 [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo),
499};
500
501
502static int
503conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff,
504 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
505
506{
507 int dir = CTINFO2DIR(ctinfo);
508 const struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info;
509 const struct tcphdr *tcph;
510 struct tcphdr _tcph;
511 const struct pptp_pkt_hdr *pptph;
512 struct pptp_pkt_hdr _pptph;
513 struct PptpControlHeader _ctlh, *ctlh;
514 union pptp_ctrl_union _pptpReq, *pptpReq;
515 unsigned int tcplen = skb->len - protoff;
516 unsigned int datalen, reqlen, nexthdr_off;
517 int oldsstate, oldcstate;
518 int ret;
519 u_int16_t msg;
520
521
522 if (ctinfo != IP_CT_ESTABLISHED &&
523 ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
524 return NF_ACCEPT;
525
526 nexthdr_off = protoff;
527 tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph);
528 BUG_ON(!tcph);
529 nexthdr_off += tcph->doff * 4;
530 datalen = tcplen - tcph->doff * 4;
531
532 pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph);
533 if (!pptph) {
534 pr_debug("no full PPTP header, can't track\n");
535 return NF_ACCEPT;
536 }
537 nexthdr_off += sizeof(_pptph);
538 datalen -= sizeof(_pptph);
539
540
541 if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL ||
542 ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) {
543 pr_debug("not a control packet\n");
544 return NF_ACCEPT;
545 }
546
547 ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh);
548 if (!ctlh)
549 return NF_ACCEPT;
550 nexthdr_off += sizeof(_ctlh);
551 datalen -= sizeof(_ctlh);
552
553 reqlen = datalen;
554 msg = ntohs(ctlh->messageType);
555 if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
556 return NF_ACCEPT;
557 if (reqlen > sizeof(*pptpReq))
558 reqlen = sizeof(*pptpReq);
559
560 pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq);
561 if (!pptpReq)
562 return NF_ACCEPT;
563
564 oldsstate = info->sstate;
565 oldcstate = info->cstate;
566
567 spin_lock_bh(&nf_pptp_lock);
568
569
570
571 if (dir == IP_CT_DIR_ORIGINAL)
572
573 ret = pptp_outbound_pkt(skb, ctlh, pptpReq, reqlen, ct,
574 ctinfo);
575 else
576
577 ret = pptp_inbound_pkt(skb, ctlh, pptpReq, reqlen, ct,
578 ctinfo);
579 pr_debug("sstate: %d->%d, cstate: %d->%d\n",
580 oldsstate, info->sstate, oldcstate, info->cstate);
581 spin_unlock_bh(&nf_pptp_lock);
582
583 return ret;
584}
585
586static const struct nf_conntrack_expect_policy pptp_exp_policy = {
587 .max_expected = 2,
588 .timeout = 5 * 60,
589};
590
591
592static struct nf_conntrack_helper pptp __read_mostly = {
593 .name = "pptp",
594 .me = THIS_MODULE,
595 .tuple.src.l3num = AF_INET,
596 .tuple.src.u.tcp.port = cpu_to_be16(PPTP_CONTROL_PORT),
597 .tuple.dst.protonum = IPPROTO_TCP,
598 .help = conntrack_pptp_help,
599 .destroy = pptp_destroy_siblings,
600 .expect_policy = &pptp_exp_policy,
601};
602
603static void nf_conntrack_pptp_net_exit(struct net *net)
604{
605 nf_ct_gre_keymap_flush(net);
606}
607
608static struct pernet_operations nf_conntrack_pptp_net_ops = {
609 .exit = nf_conntrack_pptp_net_exit,
610};
611
612static int __init nf_conntrack_pptp_init(void)
613{
614 int rv;
615
616 rv = nf_conntrack_helper_register(&pptp);
617 if (rv < 0)
618 return rv;
619 rv = register_pernet_subsys(&nf_conntrack_pptp_net_ops);
620 if (rv < 0)
621 nf_conntrack_helper_unregister(&pptp);
622 return rv;
623}
624
625static void __exit nf_conntrack_pptp_fini(void)
626{
627 nf_conntrack_helper_unregister(&pptp);
628 unregister_pernet_subsys(&nf_conntrack_pptp_net_ops);
629}
630
631module_init(nf_conntrack_pptp_init);
632module_exit(nf_conntrack_pptp_fini);
633
