?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
Merge tag 'v3.3.7' into 3.3/master
[zen-stable.git] / net / netfilter / nf_conntrack_pptp.c
blob31d56b23b9e9e743595cc721781bf215788ddd67
1 /*
2 * Connection tracking support for PPTP (Point to Point Tunneling Protocol).
3 * PPTP is a a protocol for creating virtual private networks.
4 * It is a specification defined by Microsoft and some vendors
5 * working with Microsoft. PPTP is built on top of a modified
6 * version of the Internet Generic Routing Encapsulation Protocol.
7 * GRE is defined in RFC 1701 and RFC 1702. Documentation of
8 * PPTP can be found in RFC 2637
9 *
10 * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
11 *
12 * Development of this code funded by Astaro AG (http://www.astaro.com/)
13 *
14 * Limitations:
15 * - We blindly assume that control connections are always
16 * established in PNS->PAC direction. This is a violation
17 * of RFFC2673
18 * - We can only support one single call within each session
19 * TODO:
20 * - testing of incoming PPTP calls
21 */
22
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
37 MODULE_LICENSE("GPL");
38 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
39 MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP");
40 MODULE_ALIAS("ip_conntrack_pptp");
41 MODULE_ALIAS_NFCT_HELPER("pptp");
42
43 static DEFINE_SPINLOCK(nf_pptp_lock);
44
45 int
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;
50 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_outbound);
51
52 int
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;
57 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_inbound);
58
59 void
60 (*nf_nat_pptp_hook_exp_gre)(struct nf_conntrack_expect *expect_orig,
61 struct nf_conntrack_expect *expect_reply)
62 __read_mostly;
63 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_exp_gre);
64
65 void
66 (*nf_nat_pptp_hook_expectfn)(struct nf_conn *ct,
67 struct nf_conntrack_expect *exp) __read_mostly;
68 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn);
69
70 #if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
71 /* PptpControlMessageType names */
72 const 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 };
90 EXPORT_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
100 static 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 /* increase timeout of GRE data channel conntrack entry */
108 ct->proto.gre.timeout = PPTP_GRE_TIMEOUT;
109 ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT;
110
111 /* Can you see how rusty this code is, compared with the pre-2.6.11
112 * one? That's what happened to my shiny newnat of 2002 ;( -HW */
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 /* obviously this tuple inversion only works until you do NAT */
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 /* delete other expectation. */
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
140 static 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 /* timeout GRE data connections */
174 static 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 /* try original (pns->pac) tuple */
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 /* try reply (pac->pns) tuple */
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 /* expect GRE connections (PNS->PAC and PAC->PNS direction) */
200 static 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 /* original direction, PNS->PAC */
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 /* reply direction, PAC->PNS */
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 /* Add GRE keymap entries */
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
250 out_put_both:
251 nf_ct_expect_put(exp_reply);
252 out_put_orig:
253 nf_ct_expect_put(exp_orig);
254 out:
255 return ret;
256
257 out_unexpect_both:
258 nf_ct_unexpect_related(exp_reply);
259 out_unexpect_orig:
260 nf_ct_unexpect_related(exp_orig);
261 goto out_put_both;
262 }
263
264 static inline int
265 pptp_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 /* server confirms new control session */
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 /* server confirms end of control session */
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 /* server accepted call, we now expect GRE frames */
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 /* server tells us about incoming call request */
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 /* server tells us about incoming call established */
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 /* we expect a GRE connection from PAC to PNS */
353 exp_gre(ct, cid, pcid);
354 break;
355
356 case PPTP_CALL_DISCONNECT_NOTIFY:
357 /* server confirms disconnect */
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 /* untrack this call id, unexpect GRE packets */
363 pptp_destroy_siblings(ct);
364 break;
365
366 case PPTP_WAN_ERROR_NOTIFY:
367 case PPTP_SET_LINK_INFO:
368 case PPTP_ECHO_REQUEST:
369 case PPTP_ECHO_REPLY:
370 /* I don't have to explain these ;) */
371 break;
372
373 default:
374 goto invalid;
375 }
376
377 nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound);
378 if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK)
379 return nf_nat_pptp_inbound(skb, ct, ctinfo, ctlh, pptpReq);
380 return NF_ACCEPT;
381
382 invalid:
383 pr_debug("invalid %s: type=%d cid=%u pcid=%u "
384 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
385 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
386 msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
387 ntohs(info->pns_call_id), ntohs(info->pac_call_id));
388 return NF_ACCEPT;
389 }
390
391 static inline int
392 pptp_outbound_pkt(struct sk_buff *skb,
393 struct PptpControlHeader *ctlh,
394 union pptp_ctrl_union *pptpReq,
395 unsigned int reqlen,
396 struct nf_conn *ct,
397 enum ip_conntrack_info ctinfo)
398 {
399 struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info;
400 u_int16_t msg;
401 __be16 cid = 0, pcid = 0;
402 typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound;
403
404 msg = ntohs(ctlh->messageType);
405 pr_debug("outbound control message %s\n", pptp_msg_name[msg]);
406
407 switch (msg) {
408 case PPTP_START_SESSION_REQUEST:
409 /* client requests for new control session */
410 if (info->sstate != PPTP_SESSION_NONE)
411 goto invalid;
412 info->sstate = PPTP_SESSION_REQUESTED;
413 break;
414
415 case PPTP_STOP_SESSION_REQUEST:
416 /* client requests end of control session */
417 info->sstate = PPTP_SESSION_STOPREQ;
418 break;
419
420 case PPTP_OUT_CALL_REQUEST:
421 /* client initiating connection to server */
422 if (info->sstate != PPTP_SESSION_CONFIRMED)
423 goto invalid;
424 info->cstate = PPTP_CALL_OUT_REQ;
425 /* track PNS call id */
426 cid = pptpReq->ocreq.callID;
427 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
428 info->pns_call_id = cid;
429 break;
430
431 case PPTP_IN_CALL_REPLY:
432 /* client answers incoming call */
433 if (info->cstate != PPTP_CALL_IN_REQ &&
434 info->cstate != PPTP_CALL_IN_REP)
435 goto invalid;
436
437 cid = pptpReq->icack.callID;
438 pcid = pptpReq->icack.peersCallID;
439 if (info->pac_call_id != pcid)
440 goto invalid;
441 pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg],
442 ntohs(cid), ntohs(pcid));
443
444 if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
445 /* part two of the three-way handshake */
446 info->cstate = PPTP_CALL_IN_REP;
447 info->pns_call_id = cid;
448 } else
449 info->cstate = PPTP_CALL_NONE;
450 break;
451
452 case PPTP_CALL_CLEAR_REQUEST:
453 /* client requests hangup of call */
454 if (info->sstate != PPTP_SESSION_CONFIRMED)
455 goto invalid;
456 /* FUTURE: iterate over all calls and check if
457 * call ID is valid. We don't do this without newnat,
458 * because we only know about last call */
459 info->cstate = PPTP_CALL_CLEAR_REQ;
460 break;
461
462 case PPTP_SET_LINK_INFO:
463 case PPTP_ECHO_REQUEST:
464 case PPTP_ECHO_REPLY:
465 /* I don't have to explain these ;) */
466 break;
467
468 default:
469 goto invalid;
470 }
471
472 nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound);
473 if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK)
474 return nf_nat_pptp_outbound(skb, ct, ctinfo, ctlh, pptpReq);
475 return NF_ACCEPT;
476
477 invalid:
478 pr_debug("invalid %s: type=%d cid=%u pcid=%u "
479 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
480 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
481 msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
482 ntohs(info->pns_call_id), ntohs(info->pac_call_id));
483 return NF_ACCEPT;
484 }
485
486 static const unsigned int pptp_msg_size[] = {
487 [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest),
488 [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply),
489 [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest),
490 [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply),
491 [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest),
492 [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply),
493 [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest),
494 [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply),
495 [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected),
496 [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest),
497 [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
498 [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify),
499 [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo),
500 };
501
502 /* track caller id inside control connection, call expect_related */
503 static int
504 conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff,
505 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
506
507 {
508 int dir = CTINFO2DIR(ctinfo);
509 const struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info;
510 const struct tcphdr *tcph;
511 struct tcphdr _tcph;
512 const struct pptp_pkt_hdr *pptph;
513 struct pptp_pkt_hdr _pptph;
514 struct PptpControlHeader _ctlh, *ctlh;
515 union pptp_ctrl_union _pptpReq, *pptpReq;
516 unsigned int tcplen = skb->len - protoff;
517 unsigned int datalen, reqlen, nexthdr_off;
518 int oldsstate, oldcstate;
519 int ret;
520 u_int16_t msg;
521
522 /* don't do any tracking before tcp handshake complete */
523 if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_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 /* if it's not a control message we can't do anything with it */
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 /* FIXME: We just blindly assume that the control connection is always
570 * established from PNS->PAC. However, RFC makes no guarantee */
571 if (dir == IP_CT_DIR_ORIGINAL)
572 /* client -> server (PNS -> PAC) */
573 ret = pptp_outbound_pkt(skb, ctlh, pptpReq, reqlen, ct,
574 ctinfo);
575 else
576 /* server -> client (PAC -> PNS) */
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
586 static const struct nf_conntrack_expect_policy pptp_exp_policy = {
587 .max_expected = 2,
588 .timeout = 5 * 60,
589 };
590
591 /* control protocol helper */
592 static 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
603 static void nf_conntrack_pptp_net_exit(struct net *net)
604 {
605 nf_ct_gre_keymap_flush(net);
606 }
607
608 static struct pernet_operations nf_conntrack_pptp_net_ops = {
609 .exit = nf_conntrack_pptp_net_exit,
610 };
611
612 static 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
625 static 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
631 module_init(nf_conntrack_pptp_init);
632 module_exit(nf_conntrack_pptp_fini);