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f09943fe PM |
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 <linux/netfilter/nf_conntrack_proto_gre.h> | |
32 | #include <linux/netfilter/nf_conntrack_pptp.h> | |
33 | ||
34 | #define NF_CT_PPTP_VERSION "3.1" | |
35 | ||
36 | MODULE_LICENSE("GPL"); | |
37 | MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); | |
38 | MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP"); | |
39 | MODULE_ALIAS("ip_conntrack_pptp"); | |
40 | ||
41 | static DEFINE_SPINLOCK(nf_pptp_lock); | |
42 | ||
43 | int | |
44 | (*nf_nat_pptp_hook_outbound)(struct sk_buff **pskb, | |
45 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, | |
46 | struct PptpControlHeader *ctlh, | |
47 | union pptp_ctrl_union *pptpReq) __read_mostly; | |
48 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_outbound); | |
49 | ||
50 | int | |
51 | (*nf_nat_pptp_hook_inbound)(struct sk_buff **pskb, | |
52 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, | |
53 | struct PptpControlHeader *ctlh, | |
54 | union pptp_ctrl_union *pptpReq) __read_mostly; | |
55 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_inbound); | |
56 | ||
57 | void | |
58 | (*nf_nat_pptp_hook_exp_gre)(struct nf_conntrack_expect *expect_orig, | |
59 | struct nf_conntrack_expect *expect_reply) | |
60 | __read_mostly; | |
61 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_exp_gre); | |
62 | ||
63 | void | |
64 | (*nf_nat_pptp_hook_expectfn)(struct nf_conn *ct, | |
65 | struct nf_conntrack_expect *exp) __read_mostly; | |
66 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn); | |
67 | ||
68 | #if 0 | |
69 | /* PptpControlMessageType names */ | |
70 | const char *pptp_msg_name[] = { | |
71 | "UNKNOWN_MESSAGE", | |
72 | "START_SESSION_REQUEST", | |
73 | "START_SESSION_REPLY", | |
74 | "STOP_SESSION_REQUEST", | |
75 | "STOP_SESSION_REPLY", | |
76 | "ECHO_REQUEST", | |
77 | "ECHO_REPLY", | |
78 | "OUT_CALL_REQUEST", | |
79 | "OUT_CALL_REPLY", | |
80 | "IN_CALL_REQUEST", | |
81 | "IN_CALL_REPLY", | |
82 | "IN_CALL_CONNECT", | |
83 | "CALL_CLEAR_REQUEST", | |
84 | "CALL_DISCONNECT_NOTIFY", | |
85 | "WAN_ERROR_NOTIFY", | |
86 | "SET_LINK_INFO" | |
87 | }; | |
88 | EXPORT_SYMBOL(pptp_msg_name); | |
89 | #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, __FUNCTION__, ## args) | |
90 | #else | |
91 | #define DEBUGP(format, args...) | |
92 | #endif | |
93 | ||
94 | #define SECS *HZ | |
95 | #define MINS * 60 SECS | |
96 | #define HOURS * 60 MINS | |
97 | ||
98 | #define PPTP_GRE_TIMEOUT (10 MINS) | |
99 | #define PPTP_GRE_STREAM_TIMEOUT (5 HOURS) | |
100 | ||
101 | static void pptp_expectfn(struct nf_conn *ct, | |
102 | struct nf_conntrack_expect *exp) | |
103 | { | |
104 | typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn; | |
105 | DEBUGP("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->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 | DEBUGP("trying to unexpect other dir: "); | |
125 | NF_CT_DUMP_TUPLE(&inv_t); | |
126 | ||
127 | exp_other = nf_conntrack_expect_find_get(&inv_t); | |
128 | if (exp_other) { | |
129 | /* delete other expectation. */ | |
130 | DEBUGP("found\n"); | |
131 | nf_conntrack_unexpect_related(exp_other); | |
132 | nf_conntrack_expect_put(exp_other); | |
133 | } else { | |
134 | DEBUGP("not found\n"); | |
135 | } | |
136 | } | |
137 | rcu_read_unlock(); | |
138 | } | |
139 | ||
140 | static int destroy_sibling_or_exp(const struct nf_conntrack_tuple *t) | |
141 | { | |
142 | struct nf_conntrack_tuple_hash *h; | |
143 | struct nf_conntrack_expect *exp; | |
144 | struct nf_conn *sibling; | |
145 | ||
146 | DEBUGP("trying to timeout ct or exp for tuple "); | |
147 | NF_CT_DUMP_TUPLE(t); | |
148 | ||
149 | h = nf_conntrack_find_get(t, NULL); | |
150 | if (h) { | |
151 | sibling = nf_ct_tuplehash_to_ctrack(h); | |
152 | DEBUGP("setting timeout of conntrack %p to 0\n", sibling); | |
153 | sibling->proto.gre.timeout = 0; | |
154 | sibling->proto.gre.stream_timeout = 0; | |
155 | if (del_timer(&sibling->timeout)) | |
156 | sibling->timeout.function((unsigned long)sibling); | |
157 | nf_ct_put(sibling); | |
158 | return 1; | |
159 | } else { | |
160 | exp = nf_conntrack_expect_find_get(t); | |
161 | if (exp) { | |
162 | DEBUGP("unexpect_related of expect %p\n", exp); | |
163 | nf_conntrack_unexpect_related(exp); | |
164 | nf_conntrack_expect_put(exp); | |
165 | return 1; | |
166 | } | |
167 | } | |
168 | return 0; | |
169 | } | |
170 | ||
171 | /* timeout GRE data connections */ | |
172 | static void pptp_destroy_siblings(struct nf_conn *ct) | |
173 | { | |
174 | struct nf_conn_help *help = nfct_help(ct); | |
175 | struct nf_conntrack_tuple t; | |
176 | ||
177 | nf_ct_gre_keymap_destroy(ct); | |
178 | ||
179 | /* try original (pns->pac) tuple */ | |
180 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t)); | |
181 | t.dst.protonum = IPPROTO_GRE; | |
182 | t.src.u.gre.key = help->help.ct_pptp_info.pns_call_id; | |
183 | t.dst.u.gre.key = help->help.ct_pptp_info.pac_call_id; | |
184 | if (!destroy_sibling_or_exp(&t)) | |
185 | DEBUGP("failed to timeout original pns->pac ct/exp\n"); | |
186 | ||
187 | /* try reply (pac->pns) tuple */ | |
188 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t)); | |
189 | t.dst.protonum = IPPROTO_GRE; | |
190 | t.src.u.gre.key = help->help.ct_pptp_info.pac_call_id; | |
191 | t.dst.u.gre.key = help->help.ct_pptp_info.pns_call_id; | |
192 | if (!destroy_sibling_or_exp(&t)) | |
193 | DEBUGP("failed to timeout reply pac->pns ct/exp\n"); | |
194 | } | |
195 | ||
196 | /* expect GRE connections (PNS->PAC and PAC->PNS direction) */ | |
197 | static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid) | |
198 | { | |
199 | struct nf_conntrack_expect *exp_orig, *exp_reply; | |
200 | enum ip_conntrack_dir dir; | |
201 | int ret = 1; | |
202 | typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre; | |
203 | ||
204 | exp_orig = nf_conntrack_expect_alloc(ct); | |
205 | if (exp_orig == NULL) | |
206 | goto out; | |
207 | ||
208 | exp_reply = nf_conntrack_expect_alloc(ct); | |
209 | if (exp_reply == NULL) | |
210 | goto out_put_orig; | |
211 | ||
212 | /* original direction, PNS->PAC */ | |
213 | dir = IP_CT_DIR_ORIGINAL; | |
214 | nf_conntrack_expect_init(exp_orig, ct->tuplehash[dir].tuple.src.l3num, | |
215 | &ct->tuplehash[dir].tuple.src.u3, | |
216 | &ct->tuplehash[dir].tuple.dst.u3, | |
217 | IPPROTO_GRE, &peer_callid, &callid); | |
218 | exp_orig->expectfn = pptp_expectfn; | |
219 | ||
220 | /* reply direction, PAC->PNS */ | |
221 | dir = IP_CT_DIR_REPLY; | |
222 | nf_conntrack_expect_init(exp_reply, ct->tuplehash[dir].tuple.src.l3num, | |
223 | &ct->tuplehash[dir].tuple.src.u3, | |
224 | &ct->tuplehash[dir].tuple.dst.u3, | |
225 | IPPROTO_GRE, &callid, &peer_callid); | |
226 | exp_reply->expectfn = pptp_expectfn; | |
227 | ||
228 | nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre); | |
229 | if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK) | |
230 | nf_nat_pptp_exp_gre(exp_orig, exp_reply); | |
231 | if (nf_conntrack_expect_related(exp_orig) != 0) | |
232 | goto out_put_both; | |
233 | if (nf_conntrack_expect_related(exp_reply) != 0) | |
234 | goto out_unexpect_orig; | |
235 | ||
236 | /* Add GRE keymap entries */ | |
237 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0) | |
238 | goto out_unexpect_both; | |
239 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) { | |
240 | nf_ct_gre_keymap_destroy(ct); | |
241 | goto out_unexpect_both; | |
242 | } | |
243 | ret = 0; | |
244 | ||
245 | out_put_both: | |
246 | nf_conntrack_expect_put(exp_reply); | |
247 | out_put_orig: | |
248 | nf_conntrack_expect_put(exp_orig); | |
249 | out: | |
250 | return ret; | |
251 | ||
252 | out_unexpect_both: | |
253 | nf_conntrack_unexpect_related(exp_reply); | |
254 | out_unexpect_orig: | |
255 | nf_conntrack_unexpect_related(exp_orig); | |
256 | goto out_put_both; | |
257 | } | |
258 | ||
259 | static inline int | |
260 | pptp_inbound_pkt(struct sk_buff **pskb, | |
261 | struct PptpControlHeader *ctlh, | |
262 | union pptp_ctrl_union *pptpReq, | |
263 | unsigned int reqlen, | |
264 | struct nf_conn *ct, | |
265 | enum ip_conntrack_info ctinfo) | |
266 | { | |
267 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
268 | u_int16_t msg; | |
269 | __be16 cid = 0, pcid = 0; | |
270 | typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound; | |
271 | ||
272 | msg = ntohs(ctlh->messageType); | |
273 | DEBUGP("inbound control message %s\n", pptp_msg_name[msg]); | |
274 | ||
275 | switch (msg) { | |
276 | case PPTP_START_SESSION_REPLY: | |
277 | /* server confirms new control session */ | |
278 | if (info->sstate < PPTP_SESSION_REQUESTED) | |
279 | goto invalid; | |
280 | if (pptpReq->srep.resultCode == PPTP_START_OK) | |
281 | info->sstate = PPTP_SESSION_CONFIRMED; | |
282 | else | |
283 | info->sstate = PPTP_SESSION_ERROR; | |
284 | break; | |
285 | ||
286 | case PPTP_STOP_SESSION_REPLY: | |
287 | /* server confirms end of control session */ | |
288 | if (info->sstate > PPTP_SESSION_STOPREQ) | |
289 | goto invalid; | |
290 | if (pptpReq->strep.resultCode == PPTP_STOP_OK) | |
291 | info->sstate = PPTP_SESSION_NONE; | |
292 | else | |
293 | info->sstate = PPTP_SESSION_ERROR; | |
294 | break; | |
295 | ||
296 | case PPTP_OUT_CALL_REPLY: | |
297 | /* server accepted call, we now expect GRE frames */ | |
298 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
299 | goto invalid; | |
300 | if (info->cstate != PPTP_CALL_OUT_REQ && | |
301 | info->cstate != PPTP_CALL_OUT_CONF) | |
302 | goto invalid; | |
303 | ||
304 | cid = pptpReq->ocack.callID; | |
305 | pcid = pptpReq->ocack.peersCallID; | |
306 | if (info->pns_call_id != pcid) | |
307 | goto invalid; | |
308 | DEBUGP("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], | |
309 | ntohs(cid), ntohs(pcid)); | |
310 | ||
311 | if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) { | |
312 | info->cstate = PPTP_CALL_OUT_CONF; | |
313 | info->pac_call_id = cid; | |
314 | exp_gre(ct, cid, pcid); | |
315 | } else | |
316 | info->cstate = PPTP_CALL_NONE; | |
317 | break; | |
318 | ||
319 | case PPTP_IN_CALL_REQUEST: | |
320 | /* server tells us about incoming call request */ | |
321 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
322 | goto invalid; | |
323 | ||
324 | cid = pptpReq->icreq.callID; | |
325 | DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); | |
326 | info->cstate = PPTP_CALL_IN_REQ; | |
327 | info->pac_call_id = cid; | |
328 | break; | |
329 | ||
330 | case PPTP_IN_CALL_CONNECT: | |
331 | /* server tells us about incoming call established */ | |
332 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
333 | goto invalid; | |
334 | if (info->cstate != PPTP_CALL_IN_REP && | |
335 | info->cstate != PPTP_CALL_IN_CONF) | |
336 | goto invalid; | |
337 | ||
338 | pcid = pptpReq->iccon.peersCallID; | |
339 | cid = info->pac_call_id; | |
340 | ||
341 | if (info->pns_call_id != pcid) | |
342 | goto invalid; | |
343 | ||
344 | DEBUGP("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid)); | |
345 | info->cstate = PPTP_CALL_IN_CONF; | |
346 | ||
347 | /* we expect a GRE connection from PAC to PNS */ | |
348 | exp_gre(ct, cid, pcid); | |
349 | break; | |
350 | ||
351 | case PPTP_CALL_DISCONNECT_NOTIFY: | |
352 | /* server confirms disconnect */ | |
353 | cid = pptpReq->disc.callID; | |
354 | DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); | |
355 | info->cstate = PPTP_CALL_NONE; | |
356 | ||
357 | /* untrack this call id, unexpect GRE packets */ | |
358 | pptp_destroy_siblings(ct); | |
359 | break; | |
360 | ||
361 | case PPTP_WAN_ERROR_NOTIFY: | |
362 | case PPTP_ECHO_REQUEST: | |
363 | case PPTP_ECHO_REPLY: | |
364 | /* I don't have to explain these ;) */ | |
365 | break; | |
366 | ||
367 | default: | |
368 | goto invalid; | |
369 | } | |
370 | ||
371 | nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound); | |
372 | if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK) | |
373 | return nf_nat_pptp_inbound(pskb, ct, ctinfo, ctlh, pptpReq); | |
374 | return NF_ACCEPT; | |
375 | ||
376 | invalid: | |
377 | DEBUGP("invalid %s: type=%d cid=%u pcid=%u " | |
378 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
379 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
380 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
381 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
382 | return NF_ACCEPT; | |
383 | } | |
384 | ||
385 | static inline int | |
386 | pptp_outbound_pkt(struct sk_buff **pskb, | |
387 | struct PptpControlHeader *ctlh, | |
388 | union pptp_ctrl_union *pptpReq, | |
389 | unsigned int reqlen, | |
390 | struct nf_conn *ct, | |
391 | enum ip_conntrack_info ctinfo) | |
392 | { | |
393 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
394 | u_int16_t msg; | |
395 | __be16 cid = 0, pcid = 0; | |
396 | typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound; | |
397 | ||
398 | msg = ntohs(ctlh->messageType); | |
399 | DEBUGP("outbound control message %s\n", pptp_msg_name[msg]); | |
400 | ||
401 | switch (msg) { | |
402 | case PPTP_START_SESSION_REQUEST: | |
403 | /* client requests for new control session */ | |
404 | if (info->sstate != PPTP_SESSION_NONE) | |
405 | goto invalid; | |
406 | info->sstate = PPTP_SESSION_REQUESTED; | |
407 | break; | |
408 | ||
409 | case PPTP_STOP_SESSION_REQUEST: | |
410 | /* client requests end of control session */ | |
411 | info->sstate = PPTP_SESSION_STOPREQ; | |
412 | break; | |
413 | ||
414 | case PPTP_OUT_CALL_REQUEST: | |
415 | /* client initiating connection to server */ | |
416 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
417 | goto invalid; | |
418 | info->cstate = PPTP_CALL_OUT_REQ; | |
419 | /* track PNS call id */ | |
420 | cid = pptpReq->ocreq.callID; | |
421 | DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); | |
422 | info->pns_call_id = cid; | |
423 | break; | |
424 | ||
425 | case PPTP_IN_CALL_REPLY: | |
426 | /* client answers incoming call */ | |
427 | if (info->cstate != PPTP_CALL_IN_REQ && | |
428 | info->cstate != PPTP_CALL_IN_REP) | |
429 | goto invalid; | |
430 | ||
431 | cid = pptpReq->icack.callID; | |
432 | pcid = pptpReq->icack.peersCallID; | |
433 | if (info->pac_call_id != pcid) | |
434 | goto invalid; | |
435 | DEBUGP("%s, CID=%X PCID=%X\n", pptp_msg_name[msg], | |
436 | ntohs(cid), ntohs(pcid)); | |
437 | ||
438 | if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) { | |
439 | /* part two of the three-way handshake */ | |
440 | info->cstate = PPTP_CALL_IN_REP; | |
441 | info->pns_call_id = cid; | |
442 | } else | |
443 | info->cstate = PPTP_CALL_NONE; | |
444 | break; | |
445 | ||
446 | case PPTP_CALL_CLEAR_REQUEST: | |
447 | /* client requests hangup of call */ | |
448 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
449 | goto invalid; | |
450 | /* FUTURE: iterate over all calls and check if | |
451 | * call ID is valid. We don't do this without newnat, | |
452 | * because we only know about last call */ | |
453 | info->cstate = PPTP_CALL_CLEAR_REQ; | |
454 | break; | |
455 | ||
456 | case PPTP_SET_LINK_INFO: | |
457 | case PPTP_ECHO_REQUEST: | |
458 | case PPTP_ECHO_REPLY: | |
459 | /* I don't have to explain these ;) */ | |
460 | break; | |
461 | ||
462 | default: | |
463 | goto invalid; | |
464 | } | |
465 | ||
466 | nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound); | |
467 | if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK) | |
468 | return nf_nat_pptp_outbound(pskb, ct, ctinfo, ctlh, pptpReq); | |
469 | return NF_ACCEPT; | |
470 | ||
471 | invalid: | |
472 | DEBUGP("invalid %s: type=%d cid=%u pcid=%u " | |
473 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
474 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
475 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
476 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
477 | return NF_ACCEPT; | |
478 | } | |
479 | ||
480 | static const unsigned int pptp_msg_size[] = { | |
481 | [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest), | |
482 | [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply), | |
483 | [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest), | |
484 | [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply), | |
485 | [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest), | |
486 | [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply), | |
487 | [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest), | |
488 | [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply), | |
489 | [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected), | |
490 | [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest), | |
491 | [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify), | |
492 | [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify), | |
493 | [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo), | |
494 | }; | |
495 | ||
496 | /* track caller id inside control connection, call expect_related */ | |
497 | static int | |
498 | conntrack_pptp_help(struct sk_buff **pskb, unsigned int protoff, | |
499 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) | |
500 | ||
501 | { | |
502 | int dir = CTINFO2DIR(ctinfo); | |
503 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
504 | struct tcphdr _tcph, *tcph; | |
505 | struct pptp_pkt_hdr _pptph, *pptph; | |
506 | struct PptpControlHeader _ctlh, *ctlh; | |
507 | union pptp_ctrl_union _pptpReq, *pptpReq; | |
508 | unsigned int tcplen = (*pskb)->len - protoff; | |
509 | unsigned int datalen, reqlen, nexthdr_off; | |
510 | int oldsstate, oldcstate; | |
511 | int ret; | |
512 | u_int16_t msg; | |
513 | ||
514 | /* don't do any tracking before tcp handshake complete */ | |
515 | if (ctinfo != IP_CT_ESTABLISHED && | |
516 | ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) | |
517 | return NF_ACCEPT; | |
518 | ||
519 | nexthdr_off = protoff; | |
520 | tcph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_tcph), &_tcph); | |
521 | BUG_ON(!tcph); | |
522 | nexthdr_off += tcph->doff * 4; | |
523 | datalen = tcplen - tcph->doff * 4; | |
524 | ||
525 | pptph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_pptph), &_pptph); | |
526 | if (!pptph) { | |
527 | DEBUGP("no full PPTP header, can't track\n"); | |
528 | return NF_ACCEPT; | |
529 | } | |
530 | nexthdr_off += sizeof(_pptph); | |
531 | datalen -= sizeof(_pptph); | |
532 | ||
533 | /* if it's not a control message we can't do anything with it */ | |
534 | if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL || | |
535 | ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) { | |
536 | DEBUGP("not a control packet\n"); | |
537 | return NF_ACCEPT; | |
538 | } | |
539 | ||
540 | ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh); | |
541 | if (!ctlh) | |
542 | return NF_ACCEPT; | |
543 | nexthdr_off += sizeof(_ctlh); | |
544 | datalen -= sizeof(_ctlh); | |
545 | ||
546 | reqlen = datalen; | |
547 | msg = ntohs(ctlh->messageType); | |
548 | if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg]) | |
549 | return NF_ACCEPT; | |
550 | if (reqlen > sizeof(*pptpReq)) | |
551 | reqlen = sizeof(*pptpReq); | |
552 | ||
553 | pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq); | |
554 | if (!pptpReq) | |
555 | return NF_ACCEPT; | |
556 | ||
557 | oldsstate = info->sstate; | |
558 | oldcstate = info->cstate; | |
559 | ||
560 | spin_lock_bh(&nf_pptp_lock); | |
561 | ||
562 | /* FIXME: We just blindly assume that the control connection is always | |
563 | * established from PNS->PAC. However, RFC makes no guarantee */ | |
564 | if (dir == IP_CT_DIR_ORIGINAL) | |
565 | /* client -> server (PNS -> PAC) */ | |
566 | ret = pptp_outbound_pkt(pskb, ctlh, pptpReq, reqlen, ct, | |
567 | ctinfo); | |
568 | else | |
569 | /* server -> client (PAC -> PNS) */ | |
570 | ret = pptp_inbound_pkt(pskb, ctlh, pptpReq, reqlen, ct, | |
571 | ctinfo); | |
572 | DEBUGP("sstate: %d->%d, cstate: %d->%d\n", | |
573 | oldsstate, info->sstate, oldcstate, info->cstate); | |
574 | spin_unlock_bh(&nf_pptp_lock); | |
575 | ||
576 | return ret; | |
577 | } | |
578 | ||
579 | /* control protocol helper */ | |
580 | static struct nf_conntrack_helper pptp __read_mostly = { | |
581 | .name = "pptp", | |
582 | .me = THIS_MODULE, | |
583 | .max_expected = 2, | |
584 | .timeout = 5 * 60, | |
585 | .tuple.src.l3num = AF_INET, | |
586 | .tuple.src.u.tcp.port = __constant_htons(PPTP_CONTROL_PORT), | |
587 | .tuple.dst.protonum = IPPROTO_TCP, | |
588 | .mask.src.l3num = 0xffff, | |
589 | .mask.src.u.tcp.port = __constant_htons(0xffff), | |
590 | .mask.dst.protonum = 0xff, | |
591 | .help = conntrack_pptp_help, | |
592 | .destroy = pptp_destroy_siblings, | |
593 | }; | |
594 | ||
595 | static int __init nf_conntrack_pptp_init(void) | |
596 | { | |
597 | return nf_conntrack_helper_register(&pptp); | |
598 | } | |
599 | ||
600 | static void __exit nf_conntrack_pptp_fini(void) | |
601 | { | |
602 | nf_conntrack_helper_unregister(&pptp); | |
603 | nf_ct_gre_keymap_flush(); | |
604 | } | |
605 | ||
606 | module_init(nf_conntrack_pptp_init); | |
607 | module_exit(nf_conntrack_pptp_fini); |