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