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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 if (del_timer(&sibling->timeout))
161 sibling->timeout.function((unsigned long)sibling);
162 nf_ct_put(sibling);
163 return 1;
164 } else {
165 exp = nf_ct_expect_find_get(net, zone, t);
166 if (exp) {
167 pr_debug("unexpect_related of expect %p\n", exp);
168 nf_ct_unexpect_related(exp);
169 nf_ct_expect_put(exp);
170 return 1;
171 }
172 }
173 return 0;
174}
175
176
177static void pptp_destroy_siblings(struct nf_conn *ct)
178{
179 struct net *net = nf_ct_net(ct);
180 const struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct);
181 struct nf_conntrack_tuple t;
182
183 nf_ct_gre_keymap_destroy(ct);
184
185
186 memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t));
187 t.dst.protonum = IPPROTO_GRE;
188 t.src.u.gre.key = ct_pptp_info->pns_call_id;
189 t.dst.u.gre.key = ct_pptp_info->pac_call_id;
190 if (!destroy_sibling_or_exp(net, ct, &t))
191 pr_debug("failed to timeout original pns->pac ct/exp\n");
192
193
194 memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t));
195 t.dst.protonum = IPPROTO_GRE;
196 t.src.u.gre.key = ct_pptp_info->pac_call_id;
197 t.dst.u.gre.key = ct_pptp_info->pns_call_id;
198 if (!destroy_sibling_or_exp(net, ct, &t))
199 pr_debug("failed to timeout reply pac->pns ct/exp\n");
200}
201
202
203static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid)
204{
205 struct nf_conntrack_expect *exp_orig, *exp_reply;
206 enum ip_conntrack_dir dir;
207 int ret = 1;
208 typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre;
209
210 exp_orig = nf_ct_expect_alloc(ct);
211 if (exp_orig == NULL)
212 goto out;
213
214 exp_reply = nf_ct_expect_alloc(ct);
215 if (exp_reply == NULL)
216 goto out_put_orig;
217
218
219 dir = IP_CT_DIR_ORIGINAL;
220 nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT,
221 nf_ct_l3num(ct),
222 &ct->tuplehash[dir].tuple.src.u3,
223 &ct->tuplehash[dir].tuple.dst.u3,
224 IPPROTO_GRE, &peer_callid, &callid);
225 exp_orig->expectfn = pptp_expectfn;
226
227
228 dir = IP_CT_DIR_REPLY;
229 nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT,
230 nf_ct_l3num(ct),
231 &ct->tuplehash[dir].tuple.src.u3,
232 &ct->tuplehash[dir].tuple.dst.u3,
233 IPPROTO_GRE, &callid, &peer_callid);
234 exp_reply->expectfn = pptp_expectfn;
235
236 nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre);
237 if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK)
238 nf_nat_pptp_exp_gre(exp_orig, exp_reply);
239 if (nf_ct_expect_related(exp_orig) != 0)
240 goto out_put_both;
241 if (nf_ct_expect_related(exp_reply) != 0)
242 goto out_unexpect_orig;
243
244
245 if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0)
246 goto out_unexpect_both;
247 if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) {
248 nf_ct_gre_keymap_destroy(ct);
249 goto out_unexpect_both;
250 }
251 ret = 0;
252
253out_put_both:
254 nf_ct_expect_put(exp_reply);
255out_put_orig:
256 nf_ct_expect_put(exp_orig);
257out:
258 return ret;
259
260out_unexpect_both:
261 nf_ct_unexpect_related(exp_reply);
262out_unexpect_orig:
263 nf_ct_unexpect_related(exp_orig);
264 goto out_put_both;
265}
266
267static inline int
268pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff,
269 struct PptpControlHeader *ctlh,
270 union pptp_ctrl_union *pptpReq,
271 unsigned int reqlen,
272 struct nf_conn *ct,
273 enum ip_conntrack_info ctinfo)
274{
275 struct nf_ct_pptp_master *info = nfct_help_data(ct);
276 u_int16_t msg;
277 __be16 cid = 0, pcid = 0;
278 typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound;
279
280 msg = ntohs(ctlh->messageType);
281 pr_debug("inbound control message %s\n", pptp_msg_name[msg]);
282
283 switch (msg) {
284 case PPTP_START_SESSION_REPLY:
285
286 if (info->sstate < PPTP_SESSION_REQUESTED)
287 goto invalid;
288 if (pptpReq->srep.resultCode == PPTP_START_OK)
289 info->sstate = PPTP_SESSION_CONFIRMED;
290 else
291 info->sstate = PPTP_SESSION_ERROR;
292 break;
293
294 case PPTP_STOP_SESSION_REPLY:
295
296 if (info->sstate > PPTP_SESSION_STOPREQ)
297 goto invalid;
298 if (pptpReq->strep.resultCode == PPTP_STOP_OK)
299 info->sstate = PPTP_SESSION_NONE;
300 else
301 info->sstate = PPTP_SESSION_ERROR;
302 break;
303
304 case PPTP_OUT_CALL_REPLY:
305
306 if (info->sstate != PPTP_SESSION_CONFIRMED)
307 goto invalid;
308 if (info->cstate != PPTP_CALL_OUT_REQ &&
309 info->cstate != PPTP_CALL_OUT_CONF)
310 goto invalid;
311
312 cid = pptpReq->ocack.callID;
313 pcid = pptpReq->ocack.peersCallID;
314 if (info->pns_call_id != pcid)
315 goto invalid;
316 pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg],
317 ntohs(cid), ntohs(pcid));
318
319 if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) {
320 info->cstate = PPTP_CALL_OUT_CONF;
321 info->pac_call_id = cid;
322 exp_gre(ct, cid, pcid);
323 } else
324 info->cstate = PPTP_CALL_NONE;
325 break;
326
327 case PPTP_IN_CALL_REQUEST:
328
329 if (info->sstate != PPTP_SESSION_CONFIRMED)
330 goto invalid;
331
332 cid = pptpReq->icreq.callID;
333 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
334 info->cstate = PPTP_CALL_IN_REQ;
335 info->pac_call_id = cid;
336 break;
337
338 case PPTP_IN_CALL_CONNECT:
339
340 if (info->sstate != PPTP_SESSION_CONFIRMED)
341 goto invalid;
342 if (info->cstate != PPTP_CALL_IN_REP &&
343 info->cstate != PPTP_CALL_IN_CONF)
344 goto invalid;
345
346 pcid = pptpReq->iccon.peersCallID;
347 cid = info->pac_call_id;
348
349 if (info->pns_call_id != pcid)
350 goto invalid;
351
352 pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid));
353 info->cstate = PPTP_CALL_IN_CONF;
354
355
356 exp_gre(ct, cid, pcid);
357 break;
358
359 case PPTP_CALL_DISCONNECT_NOTIFY:
360
361 cid = pptpReq->disc.callID;
362 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
363 info->cstate = PPTP_CALL_NONE;
364
365
366 pptp_destroy_siblings(ct);
367 break;
368
369 case PPTP_WAN_ERROR_NOTIFY:
370 case PPTP_SET_LINK_INFO:
371 case PPTP_ECHO_REQUEST:
372 case PPTP_ECHO_REPLY:
373
374 break;
375
376 default:
377 goto invalid;
378 }
379
380 nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound);
381 if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK)
382 return nf_nat_pptp_inbound(skb, ct, ctinfo,
383 protoff, ctlh, pptpReq);
384 return NF_ACCEPT;
385
386invalid:
387 pr_debug("invalid %s: type=%d cid=%u pcid=%u "
388 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
389 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
390 msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
391 ntohs(info->pns_call_id), ntohs(info->pac_call_id));
392 return NF_ACCEPT;
393}
394
395static inline int
396pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff,
397 struct PptpControlHeader *ctlh,
398 union pptp_ctrl_union *pptpReq,
399 unsigned int reqlen,
400 struct nf_conn *ct,
401 enum ip_conntrack_info ctinfo)
402{
403 struct nf_ct_pptp_master *info = nfct_help_data(ct);
404 u_int16_t msg;
405 __be16 cid = 0, pcid = 0;
406 typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound;
407
408 msg = ntohs(ctlh->messageType);
409 pr_debug("outbound control message %s\n", pptp_msg_name[msg]);
410
411 switch (msg) {
412 case PPTP_START_SESSION_REQUEST:
413
414 if (info->sstate != PPTP_SESSION_NONE)
415 goto invalid;
416 info->sstate = PPTP_SESSION_REQUESTED;
417 break;
418
419 case PPTP_STOP_SESSION_REQUEST:
420
421 info->sstate = PPTP_SESSION_STOPREQ;
422 break;
423
424 case PPTP_OUT_CALL_REQUEST:
425
426 if (info->sstate != PPTP_SESSION_CONFIRMED)
427 goto invalid;
428 info->cstate = PPTP_CALL_OUT_REQ;
429
430 cid = pptpReq->ocreq.callID;
431 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
432 info->pns_call_id = cid;
433 break;
434
435 case PPTP_IN_CALL_REPLY:
436
437 if (info->cstate != PPTP_CALL_IN_REQ &&
438 info->cstate != PPTP_CALL_IN_REP)
439 goto invalid;
440
441 cid = pptpReq->icack.callID;
442 pcid = pptpReq->icack.peersCallID;
443 if (info->pac_call_id != pcid)
444 goto invalid;
445 pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg],
446 ntohs(cid), ntohs(pcid));
447
448 if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
449
450 info->cstate = PPTP_CALL_IN_REP;
451 info->pns_call_id = cid;
452 } else
453 info->cstate = PPTP_CALL_NONE;
454 break;
455
456 case PPTP_CALL_CLEAR_REQUEST:
457
458 if (info->sstate != PPTP_SESSION_CONFIRMED)
459 goto invalid;
460
461
462
463 info->cstate = PPTP_CALL_CLEAR_REQ;
464 break;
465
466 case PPTP_SET_LINK_INFO:
467 case PPTP_ECHO_REQUEST:
468 case PPTP_ECHO_REPLY:
469
470 break;
471
472 default:
473 goto invalid;
474 }
475
476 nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound);
477 if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK)
478 return nf_nat_pptp_outbound(skb, ct, ctinfo,
479 protoff, ctlh, pptpReq);
480 return NF_ACCEPT;
481
482invalid:
483 pr_debug("invalid %s: type=%d cid=%u pcid=%u "
484 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
485 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
486 msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
487 ntohs(info->pns_call_id), ntohs(info->pac_call_id));
488 return NF_ACCEPT;
489}
490
491static const unsigned int pptp_msg_size[] = {
492 [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest),
493 [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply),
494 [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest),
495 [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply),
496 [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest),
497 [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply),
498 [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest),
499 [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply),
500 [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected),
501 [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest),
502 [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
503 [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify),
504 [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo),
505};
506
507
508static int
509conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff,
510 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
511
512{
513 int dir = CTINFO2DIR(ctinfo);
514 const struct nf_ct_pptp_master *info = nfct_help_data(ct);
515 const struct tcphdr *tcph;
516 struct tcphdr _tcph;
517 const struct pptp_pkt_hdr *pptph;
518 struct pptp_pkt_hdr _pptph;
519 struct PptpControlHeader _ctlh, *ctlh;
520 union pptp_ctrl_union _pptpReq, *pptpReq;
521 unsigned int tcplen = skb->len - protoff;
522 unsigned int datalen, reqlen, nexthdr_off;
523 int oldsstate, oldcstate;
524 int ret;
525 u_int16_t msg;
526
527
528 if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
529 return NF_ACCEPT;
530
531 nexthdr_off = protoff;
532 tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph);
533 BUG_ON(!tcph);
534 nexthdr_off += tcph->doff * 4;
535 datalen = tcplen - tcph->doff * 4;
536
537 pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph);
538 if (!pptph) {
539 pr_debug("no full PPTP header, can't track\n");
540 return NF_ACCEPT;
541 }
542 nexthdr_off += sizeof(_pptph);
543 datalen -= sizeof(_pptph);
544
545
546 if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL ||
547 ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) {
548 pr_debug("not a control packet\n");
549 return NF_ACCEPT;
550 }
551
552 ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh);
553 if (!ctlh)
554 return NF_ACCEPT;
555 nexthdr_off += sizeof(_ctlh);
556 datalen -= sizeof(_ctlh);
557
558 reqlen = datalen;
559 msg = ntohs(ctlh->messageType);
560 if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
561 return NF_ACCEPT;
562 if (reqlen > sizeof(*pptpReq))
563 reqlen = sizeof(*pptpReq);
564
565 pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq);
566 if (!pptpReq)
567 return NF_ACCEPT;
568
569 oldsstate = info->sstate;
570 oldcstate = info->cstate;
571
572 spin_lock_bh(&nf_pptp_lock);
573
574
575
576 if (dir == IP_CT_DIR_ORIGINAL)
577
578 ret = pptp_outbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct,
579 ctinfo);
580 else
581
582 ret = pptp_inbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct,
583 ctinfo);
584 pr_debug("sstate: %d->%d, cstate: %d->%d\n",
585 oldsstate, info->sstate, oldcstate, info->cstate);
586 spin_unlock_bh(&nf_pptp_lock);
587
588 return ret;
589}
590
591static const struct nf_conntrack_expect_policy pptp_exp_policy = {
592 .max_expected = 2,
593 .timeout = 5 * 60,
594};
595
596
597static struct nf_conntrack_helper pptp __read_mostly = {
598 .name = "pptp",
599 .me = THIS_MODULE,
600 .data_len = sizeof(struct nf_ct_pptp_master),
601 .tuple.src.l3num = AF_INET,
602 .tuple.src.u.tcp.port = cpu_to_be16(PPTP_CONTROL_PORT),
603 .tuple.dst.protonum = IPPROTO_TCP,
604 .help = conntrack_pptp_help,
605 .destroy = pptp_destroy_siblings,
606 .expect_policy = &pptp_exp_policy,
607};
608
609static int __init nf_conntrack_pptp_init(void)
610{
611 return nf_conntrack_helper_register(&pptp);
612}
613
614static void __exit nf_conntrack_pptp_fini(void)
615{
616 nf_conntrack_helper_unregister(&pptp);
617}
618
619module_init(nf_conntrack_pptp_init);
620module_exit(nf_conntrack_pptp_fini);
621
