Root/
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_ECHO_REQUEST: |
368 | case PPTP_ECHO_REPLY: |
369 | /* I don't have to explain these ;) */ |
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 | |
381 | invalid: |
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 | |
390 | static inline int |
391 | pptp_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 | /* client requests for new control session */ |
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 | /* client requests end of control session */ |
416 | info->sstate = PPTP_SESSION_STOPREQ; |
417 | break; |
418 | |
419 | case PPTP_OUT_CALL_REQUEST: |
420 | /* client initiating connection to server */ |
421 | if (info->sstate != PPTP_SESSION_CONFIRMED) |
422 | goto invalid; |
423 | info->cstate = PPTP_CALL_OUT_REQ; |
424 | /* track PNS call id */ |
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 | /* client answers incoming call */ |
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 | /* part two of the three-way handshake */ |
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 | /* client requests hangup of call */ |
453 | if (info->sstate != PPTP_SESSION_CONFIRMED) |
454 | goto invalid; |
455 | /* FUTURE: iterate over all calls and check if |
456 | * call ID is valid. We don't do this without newnat, |
457 | * because we only know about last call */ |
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 | /* I don't have to explain these ;) */ |
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 | |
476 | invalid: |
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 | |
485 | static 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 | /* track caller id inside control connection, call expect_related */ |
502 | static int |
503 | conntrack_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 | /* don't do any tracking before tcp handshake complete */ |
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 | /* 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); |
633 |
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