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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 | ||
0d53778e | 68 | #ifdef DEBUG |
f09943fe PM |
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); | |
f09943fe PM |
89 | #endif |
90 | ||
91 | #define SECS *HZ | |
92 | #define MINS * 60 SECS | |
93 | #define HOURS * 60 MINS | |
94 | ||
95 | #define PPTP_GRE_TIMEOUT (10 MINS) | |
96 | #define PPTP_GRE_STREAM_TIMEOUT (5 HOURS) | |
97 | ||
98 | static void pptp_expectfn(struct nf_conn *ct, | |
99 | struct nf_conntrack_expect *exp) | |
100 | { | |
101 | typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn; | |
0d53778e | 102 | pr_debug("increasing timeouts\n"); |
f09943fe PM |
103 | |
104 | /* increase timeout of GRE data channel conntrack entry */ | |
105 | ct->proto.gre.timeout = PPTP_GRE_TIMEOUT; | |
106 | ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT; | |
107 | ||
108 | /* Can you see how rusty this code is, compared with the pre-2.6.11 | |
109 | * one? That's what happened to my shiny newnat of 2002 ;( -HW */ | |
110 | ||
111 | rcu_read_lock(); | |
112 | nf_nat_pptp_expectfn = rcu_dereference(nf_nat_pptp_hook_expectfn); | |
7399072a | 113 | if (nf_nat_pptp_expectfn && ct->master->status & IPS_NAT_MASK) |
f09943fe PM |
114 | nf_nat_pptp_expectfn(ct, exp); |
115 | else { | |
116 | struct nf_conntrack_tuple inv_t; | |
117 | struct nf_conntrack_expect *exp_other; | |
118 | ||
119 | /* obviously this tuple inversion only works until you do NAT */ | |
120 | nf_ct_invert_tuplepr(&inv_t, &exp->tuple); | |
0d53778e | 121 | pr_debug("trying to unexpect other dir: "); |
f09943fe PM |
122 | NF_CT_DUMP_TUPLE(&inv_t); |
123 | ||
6823645d | 124 | exp_other = nf_ct_expect_find_get(&inv_t); |
f09943fe PM |
125 | if (exp_other) { |
126 | /* delete other expectation. */ | |
0d53778e | 127 | pr_debug("found\n"); |
6823645d PM |
128 | nf_ct_unexpect_related(exp_other); |
129 | nf_ct_expect_put(exp_other); | |
f09943fe | 130 | } else { |
0d53778e | 131 | pr_debug("not found\n"); |
f09943fe PM |
132 | } |
133 | } | |
134 | rcu_read_unlock(); | |
135 | } | |
136 | ||
137 | static int destroy_sibling_or_exp(const struct nf_conntrack_tuple *t) | |
138 | { | |
139 | struct nf_conntrack_tuple_hash *h; | |
140 | struct nf_conntrack_expect *exp; | |
141 | struct nf_conn *sibling; | |
142 | ||
0d53778e | 143 | pr_debug("trying to timeout ct or exp for tuple "); |
f09943fe PM |
144 | NF_CT_DUMP_TUPLE(t); |
145 | ||
330f7db5 | 146 | h = nf_conntrack_find_get(t); |
f09943fe PM |
147 | if (h) { |
148 | sibling = nf_ct_tuplehash_to_ctrack(h); | |
0d53778e | 149 | pr_debug("setting timeout of conntrack %p to 0\n", sibling); |
f09943fe PM |
150 | sibling->proto.gre.timeout = 0; |
151 | sibling->proto.gre.stream_timeout = 0; | |
152 | if (del_timer(&sibling->timeout)) | |
153 | sibling->timeout.function((unsigned long)sibling); | |
154 | nf_ct_put(sibling); | |
155 | return 1; | |
156 | } else { | |
6823645d | 157 | exp = nf_ct_expect_find_get(t); |
f09943fe | 158 | if (exp) { |
0d53778e | 159 | pr_debug("unexpect_related of expect %p\n", exp); |
6823645d PM |
160 | nf_ct_unexpect_related(exp); |
161 | nf_ct_expect_put(exp); | |
f09943fe PM |
162 | return 1; |
163 | } | |
164 | } | |
165 | return 0; | |
166 | } | |
167 | ||
168 | /* timeout GRE data connections */ | |
169 | static void pptp_destroy_siblings(struct nf_conn *ct) | |
170 | { | |
171 | struct nf_conn_help *help = nfct_help(ct); | |
172 | struct nf_conntrack_tuple t; | |
173 | ||
174 | nf_ct_gre_keymap_destroy(ct); | |
175 | ||
176 | /* try original (pns->pac) tuple */ | |
177 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t)); | |
178 | t.dst.protonum = IPPROTO_GRE; | |
179 | t.src.u.gre.key = help->help.ct_pptp_info.pns_call_id; | |
180 | t.dst.u.gre.key = help->help.ct_pptp_info.pac_call_id; | |
181 | if (!destroy_sibling_or_exp(&t)) | |
0d53778e | 182 | pr_debug("failed to timeout original pns->pac ct/exp\n"); |
f09943fe PM |
183 | |
184 | /* try reply (pac->pns) tuple */ | |
185 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t)); | |
186 | t.dst.protonum = IPPROTO_GRE; | |
187 | t.src.u.gre.key = help->help.ct_pptp_info.pac_call_id; | |
188 | t.dst.u.gre.key = help->help.ct_pptp_info.pns_call_id; | |
189 | if (!destroy_sibling_or_exp(&t)) | |
0d53778e | 190 | pr_debug("failed to timeout reply pac->pns ct/exp\n"); |
f09943fe PM |
191 | } |
192 | ||
193 | /* expect GRE connections (PNS->PAC and PAC->PNS direction) */ | |
194 | static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid) | |
195 | { | |
196 | struct nf_conntrack_expect *exp_orig, *exp_reply; | |
197 | enum ip_conntrack_dir dir; | |
198 | int ret = 1; | |
199 | typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre; | |
200 | ||
6823645d | 201 | exp_orig = nf_ct_expect_alloc(ct); |
f09943fe PM |
202 | if (exp_orig == NULL) |
203 | goto out; | |
204 | ||
6823645d | 205 | exp_reply = nf_ct_expect_alloc(ct); |
f09943fe PM |
206 | if (exp_reply == NULL) |
207 | goto out_put_orig; | |
208 | ||
209 | /* original direction, PNS->PAC */ | |
210 | dir = IP_CT_DIR_ORIGINAL; | |
6823645d PM |
211 | nf_ct_expect_init(exp_orig, ct->tuplehash[dir].tuple.src.l3num, |
212 | &ct->tuplehash[dir].tuple.src.u3, | |
213 | &ct->tuplehash[dir].tuple.dst.u3, | |
214 | IPPROTO_GRE, &peer_callid, &callid); | |
f09943fe PM |
215 | exp_orig->expectfn = pptp_expectfn; |
216 | ||
217 | /* reply direction, PAC->PNS */ | |
218 | dir = IP_CT_DIR_REPLY; | |
6823645d PM |
219 | nf_ct_expect_init(exp_reply, ct->tuplehash[dir].tuple.src.l3num, |
220 | &ct->tuplehash[dir].tuple.src.u3, | |
221 | &ct->tuplehash[dir].tuple.dst.u3, | |
222 | IPPROTO_GRE, &callid, &peer_callid); | |
f09943fe PM |
223 | exp_reply->expectfn = pptp_expectfn; |
224 | ||
225 | nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre); | |
226 | if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK) | |
227 | nf_nat_pptp_exp_gre(exp_orig, exp_reply); | |
6823645d | 228 | if (nf_ct_expect_related(exp_orig) != 0) |
f09943fe | 229 | goto out_put_both; |
6823645d | 230 | if (nf_ct_expect_related(exp_reply) != 0) |
f09943fe PM |
231 | goto out_unexpect_orig; |
232 | ||
233 | /* Add GRE keymap entries */ | |
234 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0) | |
235 | goto out_unexpect_both; | |
236 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) { | |
237 | nf_ct_gre_keymap_destroy(ct); | |
238 | goto out_unexpect_both; | |
239 | } | |
240 | ret = 0; | |
241 | ||
242 | out_put_both: | |
6823645d | 243 | nf_ct_expect_put(exp_reply); |
f09943fe | 244 | out_put_orig: |
6823645d | 245 | nf_ct_expect_put(exp_orig); |
f09943fe PM |
246 | out: |
247 | return ret; | |
248 | ||
249 | out_unexpect_both: | |
6823645d | 250 | nf_ct_unexpect_related(exp_reply); |
f09943fe | 251 | out_unexpect_orig: |
6823645d | 252 | nf_ct_unexpect_related(exp_orig); |
f09943fe PM |
253 | goto out_put_both; |
254 | } | |
255 | ||
256 | static inline int | |
257 | pptp_inbound_pkt(struct sk_buff **pskb, | |
258 | struct PptpControlHeader *ctlh, | |
259 | union pptp_ctrl_union *pptpReq, | |
260 | unsigned int reqlen, | |
261 | struct nf_conn *ct, | |
262 | enum ip_conntrack_info ctinfo) | |
263 | { | |
264 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
265 | u_int16_t msg; | |
266 | __be16 cid = 0, pcid = 0; | |
267 | typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound; | |
268 | ||
269 | msg = ntohs(ctlh->messageType); | |
0d53778e | 270 | pr_debug("inbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
271 | |
272 | switch (msg) { | |
273 | case PPTP_START_SESSION_REPLY: | |
274 | /* server confirms new control session */ | |
275 | if (info->sstate < PPTP_SESSION_REQUESTED) | |
276 | goto invalid; | |
277 | if (pptpReq->srep.resultCode == PPTP_START_OK) | |
278 | info->sstate = PPTP_SESSION_CONFIRMED; | |
279 | else | |
280 | info->sstate = PPTP_SESSION_ERROR; | |
281 | break; | |
282 | ||
283 | case PPTP_STOP_SESSION_REPLY: | |
284 | /* server confirms end of control session */ | |
285 | if (info->sstate > PPTP_SESSION_STOPREQ) | |
286 | goto invalid; | |
287 | if (pptpReq->strep.resultCode == PPTP_STOP_OK) | |
288 | info->sstate = PPTP_SESSION_NONE; | |
289 | else | |
290 | info->sstate = PPTP_SESSION_ERROR; | |
291 | break; | |
292 | ||
293 | case PPTP_OUT_CALL_REPLY: | |
294 | /* server accepted call, we now expect GRE frames */ | |
295 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
296 | goto invalid; | |
297 | if (info->cstate != PPTP_CALL_OUT_REQ && | |
298 | info->cstate != PPTP_CALL_OUT_CONF) | |
299 | goto invalid; | |
300 | ||
301 | cid = pptpReq->ocack.callID; | |
302 | pcid = pptpReq->ocack.peersCallID; | |
303 | if (info->pns_call_id != pcid) | |
304 | goto invalid; | |
0d53778e PM |
305 | pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], |
306 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
307 | |
308 | if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) { | |
309 | info->cstate = PPTP_CALL_OUT_CONF; | |
310 | info->pac_call_id = cid; | |
311 | exp_gre(ct, cid, pcid); | |
312 | } else | |
313 | info->cstate = PPTP_CALL_NONE; | |
314 | break; | |
315 | ||
316 | case PPTP_IN_CALL_REQUEST: | |
317 | /* server tells us about incoming call request */ | |
318 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
319 | goto invalid; | |
320 | ||
321 | cid = pptpReq->icreq.callID; | |
0d53778e | 322 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
323 | info->cstate = PPTP_CALL_IN_REQ; |
324 | info->pac_call_id = cid; | |
325 | break; | |
326 | ||
327 | case PPTP_IN_CALL_CONNECT: | |
328 | /* server tells us about incoming call established */ | |
329 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
330 | goto invalid; | |
331 | if (info->cstate != PPTP_CALL_IN_REP && | |
332 | info->cstate != PPTP_CALL_IN_CONF) | |
333 | goto invalid; | |
334 | ||
335 | pcid = pptpReq->iccon.peersCallID; | |
336 | cid = info->pac_call_id; | |
337 | ||
338 | if (info->pns_call_id != pcid) | |
339 | goto invalid; | |
340 | ||
0d53778e | 341 | pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid)); |
f09943fe PM |
342 | info->cstate = PPTP_CALL_IN_CONF; |
343 | ||
344 | /* we expect a GRE connection from PAC to PNS */ | |
345 | exp_gre(ct, cid, pcid); | |
346 | break; | |
347 | ||
348 | case PPTP_CALL_DISCONNECT_NOTIFY: | |
349 | /* server confirms disconnect */ | |
350 | cid = pptpReq->disc.callID; | |
0d53778e | 351 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
352 | info->cstate = PPTP_CALL_NONE; |
353 | ||
354 | /* untrack this call id, unexpect GRE packets */ | |
355 | pptp_destroy_siblings(ct); | |
356 | break; | |
357 | ||
358 | case PPTP_WAN_ERROR_NOTIFY: | |
359 | case PPTP_ECHO_REQUEST: | |
360 | case PPTP_ECHO_REPLY: | |
361 | /* I don't have to explain these ;) */ | |
362 | break; | |
363 | ||
364 | default: | |
365 | goto invalid; | |
366 | } | |
367 | ||
368 | nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound); | |
369 | if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK) | |
370 | return nf_nat_pptp_inbound(pskb, ct, ctinfo, ctlh, pptpReq); | |
371 | return NF_ACCEPT; | |
372 | ||
373 | invalid: | |
0d53778e PM |
374 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
375 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
376 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
377 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
378 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
379 | return NF_ACCEPT; |
380 | } | |
381 | ||
382 | static inline int | |
383 | pptp_outbound_pkt(struct sk_buff **pskb, | |
384 | struct PptpControlHeader *ctlh, | |
385 | union pptp_ctrl_union *pptpReq, | |
386 | unsigned int reqlen, | |
387 | struct nf_conn *ct, | |
388 | enum ip_conntrack_info ctinfo) | |
389 | { | |
390 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
391 | u_int16_t msg; | |
392 | __be16 cid = 0, pcid = 0; | |
393 | typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound; | |
394 | ||
395 | msg = ntohs(ctlh->messageType); | |
0d53778e | 396 | pr_debug("outbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
397 | |
398 | switch (msg) { | |
399 | case PPTP_START_SESSION_REQUEST: | |
400 | /* client requests for new control session */ | |
401 | if (info->sstate != PPTP_SESSION_NONE) | |
402 | goto invalid; | |
403 | info->sstate = PPTP_SESSION_REQUESTED; | |
404 | break; | |
405 | ||
406 | case PPTP_STOP_SESSION_REQUEST: | |
407 | /* client requests end of control session */ | |
408 | info->sstate = PPTP_SESSION_STOPREQ; | |
409 | break; | |
410 | ||
411 | case PPTP_OUT_CALL_REQUEST: | |
412 | /* client initiating connection to server */ | |
413 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
414 | goto invalid; | |
415 | info->cstate = PPTP_CALL_OUT_REQ; | |
416 | /* track PNS call id */ | |
417 | cid = pptpReq->ocreq.callID; | |
0d53778e | 418 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
419 | info->pns_call_id = cid; |
420 | break; | |
421 | ||
422 | case PPTP_IN_CALL_REPLY: | |
423 | /* client answers incoming call */ | |
424 | if (info->cstate != PPTP_CALL_IN_REQ && | |
425 | info->cstate != PPTP_CALL_IN_REP) | |
426 | goto invalid; | |
427 | ||
428 | cid = pptpReq->icack.callID; | |
429 | pcid = pptpReq->icack.peersCallID; | |
430 | if (info->pac_call_id != pcid) | |
431 | goto invalid; | |
0d53778e PM |
432 | pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg], |
433 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
434 | |
435 | if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) { | |
436 | /* part two of the three-way handshake */ | |
437 | info->cstate = PPTP_CALL_IN_REP; | |
438 | info->pns_call_id = cid; | |
439 | } else | |
440 | info->cstate = PPTP_CALL_NONE; | |
441 | break; | |
442 | ||
443 | case PPTP_CALL_CLEAR_REQUEST: | |
444 | /* client requests hangup of call */ | |
445 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
446 | goto invalid; | |
447 | /* FUTURE: iterate over all calls and check if | |
448 | * call ID is valid. We don't do this without newnat, | |
449 | * because we only know about last call */ | |
450 | info->cstate = PPTP_CALL_CLEAR_REQ; | |
451 | break; | |
452 | ||
453 | case PPTP_SET_LINK_INFO: | |
454 | case PPTP_ECHO_REQUEST: | |
455 | case PPTP_ECHO_REPLY: | |
456 | /* I don't have to explain these ;) */ | |
457 | break; | |
458 | ||
459 | default: | |
460 | goto invalid; | |
461 | } | |
462 | ||
463 | nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound); | |
464 | if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK) | |
465 | return nf_nat_pptp_outbound(pskb, ct, ctinfo, ctlh, pptpReq); | |
466 | return NF_ACCEPT; | |
467 | ||
468 | invalid: | |
0d53778e PM |
469 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
470 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
471 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
472 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
473 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
474 | return NF_ACCEPT; |
475 | } | |
476 | ||
477 | static const unsigned int pptp_msg_size[] = { | |
478 | [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest), | |
479 | [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply), | |
480 | [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest), | |
481 | [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply), | |
482 | [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest), | |
483 | [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply), | |
484 | [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest), | |
485 | [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply), | |
486 | [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected), | |
487 | [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest), | |
488 | [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify), | |
489 | [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify), | |
490 | [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo), | |
491 | }; | |
492 | ||
493 | /* track caller id inside control connection, call expect_related */ | |
494 | static int | |
495 | conntrack_pptp_help(struct sk_buff **pskb, unsigned int protoff, | |
496 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) | |
497 | ||
498 | { | |
499 | int dir = CTINFO2DIR(ctinfo); | |
500 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
501 | struct tcphdr _tcph, *tcph; | |
502 | struct pptp_pkt_hdr _pptph, *pptph; | |
503 | struct PptpControlHeader _ctlh, *ctlh; | |
504 | union pptp_ctrl_union _pptpReq, *pptpReq; | |
505 | unsigned int tcplen = (*pskb)->len - protoff; | |
506 | unsigned int datalen, reqlen, nexthdr_off; | |
507 | int oldsstate, oldcstate; | |
508 | int ret; | |
509 | u_int16_t msg; | |
510 | ||
511 | /* don't do any tracking before tcp handshake complete */ | |
512 | if (ctinfo != IP_CT_ESTABLISHED && | |
513 | ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) | |
514 | return NF_ACCEPT; | |
515 | ||
516 | nexthdr_off = protoff; | |
517 | tcph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_tcph), &_tcph); | |
518 | BUG_ON(!tcph); | |
519 | nexthdr_off += tcph->doff * 4; | |
601e68e1 | 520 | datalen = tcplen - tcph->doff * 4; |
f09943fe PM |
521 | |
522 | pptph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_pptph), &_pptph); | |
523 | if (!pptph) { | |
0d53778e | 524 | pr_debug("no full PPTP header, can't track\n"); |
f09943fe PM |
525 | return NF_ACCEPT; |
526 | } | |
527 | nexthdr_off += sizeof(_pptph); | |
528 | datalen -= sizeof(_pptph); | |
529 | ||
530 | /* if it's not a control message we can't do anything with it */ | |
531 | if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL || | |
532 | ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) { | |
0d53778e | 533 | pr_debug("not a control packet\n"); |
f09943fe PM |
534 | return NF_ACCEPT; |
535 | } | |
536 | ||
537 | ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh); | |
538 | if (!ctlh) | |
539 | return NF_ACCEPT; | |
540 | nexthdr_off += sizeof(_ctlh); | |
541 | datalen -= sizeof(_ctlh); | |
542 | ||
543 | reqlen = datalen; | |
544 | msg = ntohs(ctlh->messageType); | |
545 | if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg]) | |
546 | return NF_ACCEPT; | |
547 | if (reqlen > sizeof(*pptpReq)) | |
548 | reqlen = sizeof(*pptpReq); | |
549 | ||
550 | pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq); | |
551 | if (!pptpReq) | |
552 | return NF_ACCEPT; | |
553 | ||
554 | oldsstate = info->sstate; | |
555 | oldcstate = info->cstate; | |
556 | ||
557 | spin_lock_bh(&nf_pptp_lock); | |
558 | ||
559 | /* FIXME: We just blindly assume that the control connection is always | |
560 | * established from PNS->PAC. However, RFC makes no guarantee */ | |
561 | if (dir == IP_CT_DIR_ORIGINAL) | |
562 | /* client -> server (PNS -> PAC) */ | |
563 | ret = pptp_outbound_pkt(pskb, ctlh, pptpReq, reqlen, ct, | |
564 | ctinfo); | |
565 | else | |
566 | /* server -> client (PAC -> PNS) */ | |
567 | ret = pptp_inbound_pkt(pskb, ctlh, pptpReq, reqlen, ct, | |
568 | ctinfo); | |
0d53778e PM |
569 | pr_debug("sstate: %d->%d, cstate: %d->%d\n", |
570 | oldsstate, info->sstate, oldcstate, info->cstate); | |
f09943fe PM |
571 | spin_unlock_bh(&nf_pptp_lock); |
572 | ||
573 | return ret; | |
574 | } | |
575 | ||
576 | /* control protocol helper */ | |
577 | static struct nf_conntrack_helper pptp __read_mostly = { | |
578 | .name = "pptp", | |
579 | .me = THIS_MODULE, | |
580 | .max_expected = 2, | |
581 | .timeout = 5 * 60, | |
582 | .tuple.src.l3num = AF_INET, | |
583 | .tuple.src.u.tcp.port = __constant_htons(PPTP_CONTROL_PORT), | |
584 | .tuple.dst.protonum = IPPROTO_TCP, | |
f09943fe PM |
585 | .help = conntrack_pptp_help, |
586 | .destroy = pptp_destroy_siblings, | |
587 | }; | |
588 | ||
589 | static int __init nf_conntrack_pptp_init(void) | |
590 | { | |
591 | return nf_conntrack_helper_register(&pptp); | |
592 | } | |
593 | ||
594 | static void __exit nf_conntrack_pptp_fini(void) | |
595 | { | |
596 | nf_conntrack_helper_unregister(&pptp); | |
597 | nf_ct_gre_keymap_flush(); | |
598 | } | |
599 | ||
600 | module_init(nf_conntrack_pptp_init); | |
601 | module_exit(nf_conntrack_pptp_fini); |