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Commit | Line | Data |
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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 | |
3db05fea | 44 | (*nf_nat_pptp_hook_outbound)(struct sk_buff *skb, |
f09943fe PM |
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 | |
3db05fea | 51 | (*nf_nat_pptp_hook_inbound)(struct sk_buff *skb, |
f09943fe PM |
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 | 69 | /* PptpControlMessageType names */ |
9ddd0ed0 | 70 | const char *const pptp_msg_name[] = { |
f09943fe PM |
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 | { | |
9ddd0ed0 | 139 | const struct nf_conntrack_tuple_hash *h; |
f09943fe PM |
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 | { | |
9ddd0ed0 | 171 | const struct nf_conn_help *help = nfct_help(ct); |
f09943fe PM |
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; | |
6002f266 PM |
211 | nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT, |
212 | ct->tuplehash[dir].tuple.src.l3num, | |
6823645d PM |
213 | &ct->tuplehash[dir].tuple.src.u3, |
214 | &ct->tuplehash[dir].tuple.dst.u3, | |
215 | IPPROTO_GRE, &peer_callid, &callid); | |
f09943fe PM |
216 | exp_orig->expectfn = pptp_expectfn; |
217 | ||
218 | /* reply direction, PAC->PNS */ | |
219 | dir = IP_CT_DIR_REPLY; | |
6002f266 PM |
220 | nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT, |
221 | ct->tuplehash[dir].tuple.src.l3num, | |
6823645d PM |
222 | &ct->tuplehash[dir].tuple.src.u3, |
223 | &ct->tuplehash[dir].tuple.dst.u3, | |
224 | IPPROTO_GRE, &callid, &peer_callid); | |
f09943fe PM |
225 | exp_reply->expectfn = pptp_expectfn; |
226 | ||
227 | nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre); | |
228 | if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK) | |
229 | nf_nat_pptp_exp_gre(exp_orig, exp_reply); | |
6823645d | 230 | if (nf_ct_expect_related(exp_orig) != 0) |
f09943fe | 231 | goto out_put_both; |
6823645d | 232 | if (nf_ct_expect_related(exp_reply) != 0) |
f09943fe PM |
233 | goto out_unexpect_orig; |
234 | ||
235 | /* Add GRE keymap entries */ | |
236 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0) | |
237 | goto out_unexpect_both; | |
238 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) { | |
239 | nf_ct_gre_keymap_destroy(ct); | |
240 | goto out_unexpect_both; | |
241 | } | |
242 | ret = 0; | |
243 | ||
244 | out_put_both: | |
6823645d | 245 | nf_ct_expect_put(exp_reply); |
f09943fe | 246 | out_put_orig: |
6823645d | 247 | nf_ct_expect_put(exp_orig); |
f09943fe PM |
248 | out: |
249 | return ret; | |
250 | ||
251 | out_unexpect_both: | |
6823645d | 252 | nf_ct_unexpect_related(exp_reply); |
f09943fe | 253 | out_unexpect_orig: |
6823645d | 254 | nf_ct_unexpect_related(exp_orig); |
f09943fe PM |
255 | goto out_put_both; |
256 | } | |
257 | ||
258 | static inline int | |
3db05fea | 259 | pptp_inbound_pkt(struct sk_buff *skb, |
f09943fe PM |
260 | struct PptpControlHeader *ctlh, |
261 | union pptp_ctrl_union *pptpReq, | |
262 | unsigned int reqlen, | |
263 | struct nf_conn *ct, | |
264 | enum ip_conntrack_info ctinfo) | |
265 | { | |
266 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
267 | u_int16_t msg; | |
268 | __be16 cid = 0, pcid = 0; | |
269 | typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound; | |
270 | ||
271 | msg = ntohs(ctlh->messageType); | |
0d53778e | 272 | pr_debug("inbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
273 | |
274 | switch (msg) { | |
275 | case PPTP_START_SESSION_REPLY: | |
276 | /* server confirms new control session */ | |
277 | if (info->sstate < PPTP_SESSION_REQUESTED) | |
278 | goto invalid; | |
279 | if (pptpReq->srep.resultCode == PPTP_START_OK) | |
280 | info->sstate = PPTP_SESSION_CONFIRMED; | |
281 | else | |
282 | info->sstate = PPTP_SESSION_ERROR; | |
283 | break; | |
284 | ||
285 | case PPTP_STOP_SESSION_REPLY: | |
286 | /* server confirms end of control session */ | |
287 | if (info->sstate > PPTP_SESSION_STOPREQ) | |
288 | goto invalid; | |
289 | if (pptpReq->strep.resultCode == PPTP_STOP_OK) | |
290 | info->sstate = PPTP_SESSION_NONE; | |
291 | else | |
292 | info->sstate = PPTP_SESSION_ERROR; | |
293 | break; | |
294 | ||
295 | case PPTP_OUT_CALL_REPLY: | |
296 | /* server accepted call, we now expect GRE frames */ | |
297 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
298 | goto invalid; | |
299 | if (info->cstate != PPTP_CALL_OUT_REQ && | |
300 | info->cstate != PPTP_CALL_OUT_CONF) | |
301 | goto invalid; | |
302 | ||
303 | cid = pptpReq->ocack.callID; | |
304 | pcid = pptpReq->ocack.peersCallID; | |
305 | if (info->pns_call_id != pcid) | |
306 | goto invalid; | |
0d53778e PM |
307 | pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], |
308 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
309 | |
310 | if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) { | |
311 | info->cstate = PPTP_CALL_OUT_CONF; | |
312 | info->pac_call_id = cid; | |
313 | exp_gre(ct, cid, pcid); | |
314 | } else | |
315 | info->cstate = PPTP_CALL_NONE; | |
316 | break; | |
317 | ||
318 | case PPTP_IN_CALL_REQUEST: | |
319 | /* server tells us about incoming call request */ | |
320 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
321 | goto invalid; | |
322 | ||
323 | cid = pptpReq->icreq.callID; | |
0d53778e | 324 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
325 | info->cstate = PPTP_CALL_IN_REQ; |
326 | info->pac_call_id = cid; | |
327 | break; | |
328 | ||
329 | case PPTP_IN_CALL_CONNECT: | |
330 | /* server tells us about incoming call established */ | |
331 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
332 | goto invalid; | |
333 | if (info->cstate != PPTP_CALL_IN_REP && | |
334 | info->cstate != PPTP_CALL_IN_CONF) | |
335 | goto invalid; | |
336 | ||
337 | pcid = pptpReq->iccon.peersCallID; | |
338 | cid = info->pac_call_id; | |
339 | ||
340 | if (info->pns_call_id != pcid) | |
341 | goto invalid; | |
342 | ||
0d53778e | 343 | pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid)); |
f09943fe PM |
344 | info->cstate = PPTP_CALL_IN_CONF; |
345 | ||
346 | /* we expect a GRE connection from PAC to PNS */ | |
347 | exp_gre(ct, cid, pcid); | |
348 | break; | |
349 | ||
350 | case PPTP_CALL_DISCONNECT_NOTIFY: | |
351 | /* server confirms disconnect */ | |
352 | cid = pptpReq->disc.callID; | |
0d53778e | 353 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
354 | info->cstate = PPTP_CALL_NONE; |
355 | ||
356 | /* untrack this call id, unexpect GRE packets */ | |
357 | pptp_destroy_siblings(ct); | |
358 | break; | |
359 | ||
360 | case PPTP_WAN_ERROR_NOTIFY: | |
361 | case PPTP_ECHO_REQUEST: | |
362 | case PPTP_ECHO_REPLY: | |
363 | /* I don't have to explain these ;) */ | |
364 | break; | |
365 | ||
366 | default: | |
367 | goto invalid; | |
368 | } | |
369 | ||
370 | nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound); | |
371 | if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK) | |
3db05fea | 372 | return nf_nat_pptp_inbound(skb, ct, ctinfo, ctlh, pptpReq); |
f09943fe PM |
373 | return NF_ACCEPT; |
374 | ||
375 | invalid: | |
0d53778e PM |
376 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
377 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
378 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
379 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
380 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
381 | return NF_ACCEPT; |
382 | } | |
383 | ||
384 | static inline int | |
3db05fea | 385 | pptp_outbound_pkt(struct sk_buff *skb, |
f09943fe PM |
386 | struct PptpControlHeader *ctlh, |
387 | union pptp_ctrl_union *pptpReq, | |
388 | unsigned int reqlen, | |
389 | struct nf_conn *ct, | |
390 | enum ip_conntrack_info ctinfo) | |
391 | { | |
392 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
393 | u_int16_t msg; | |
394 | __be16 cid = 0, pcid = 0; | |
395 | typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound; | |
396 | ||
397 | msg = ntohs(ctlh->messageType); | |
0d53778e | 398 | pr_debug("outbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
399 | |
400 | switch (msg) { | |
401 | case PPTP_START_SESSION_REQUEST: | |
402 | /* client requests for new control session */ | |
403 | if (info->sstate != PPTP_SESSION_NONE) | |
404 | goto invalid; | |
405 | info->sstate = PPTP_SESSION_REQUESTED; | |
406 | break; | |
407 | ||
408 | case PPTP_STOP_SESSION_REQUEST: | |
409 | /* client requests end of control session */ | |
410 | info->sstate = PPTP_SESSION_STOPREQ; | |
411 | break; | |
412 | ||
413 | case PPTP_OUT_CALL_REQUEST: | |
414 | /* client initiating connection to server */ | |
415 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
416 | goto invalid; | |
417 | info->cstate = PPTP_CALL_OUT_REQ; | |
418 | /* track PNS call id */ | |
419 | cid = pptpReq->ocreq.callID; | |
0d53778e | 420 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
421 | info->pns_call_id = cid; |
422 | break; | |
423 | ||
424 | case PPTP_IN_CALL_REPLY: | |
425 | /* client answers incoming call */ | |
426 | if (info->cstate != PPTP_CALL_IN_REQ && | |
427 | info->cstate != PPTP_CALL_IN_REP) | |
428 | goto invalid; | |
429 | ||
430 | cid = pptpReq->icack.callID; | |
431 | pcid = pptpReq->icack.peersCallID; | |
432 | if (info->pac_call_id != pcid) | |
433 | goto invalid; | |
0d53778e PM |
434 | pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg], |
435 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
436 | |
437 | if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) { | |
438 | /* part two of the three-way handshake */ | |
439 | info->cstate = PPTP_CALL_IN_REP; | |
440 | info->pns_call_id = cid; | |
441 | } else | |
442 | info->cstate = PPTP_CALL_NONE; | |
443 | break; | |
444 | ||
445 | case PPTP_CALL_CLEAR_REQUEST: | |
446 | /* client requests hangup of call */ | |
447 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
448 | goto invalid; | |
449 | /* FUTURE: iterate over all calls and check if | |
450 | * call ID is valid. We don't do this without newnat, | |
451 | * because we only know about last call */ | |
452 | info->cstate = PPTP_CALL_CLEAR_REQ; | |
453 | break; | |
454 | ||
455 | case PPTP_SET_LINK_INFO: | |
456 | case PPTP_ECHO_REQUEST: | |
457 | case PPTP_ECHO_REPLY: | |
458 | /* I don't have to explain these ;) */ | |
459 | break; | |
460 | ||
461 | default: | |
462 | goto invalid; | |
463 | } | |
464 | ||
465 | nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound); | |
466 | if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK) | |
3db05fea | 467 | return nf_nat_pptp_outbound(skb, ct, ctinfo, ctlh, pptpReq); |
f09943fe PM |
468 | return NF_ACCEPT; |
469 | ||
470 | invalid: | |
0d53778e PM |
471 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
472 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
473 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
474 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
475 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
476 | return NF_ACCEPT; |
477 | } | |
478 | ||
479 | static const unsigned int pptp_msg_size[] = { | |
480 | [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest), | |
481 | [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply), | |
482 | [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest), | |
483 | [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply), | |
484 | [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest), | |
485 | [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply), | |
486 | [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest), | |
487 | [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply), | |
488 | [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected), | |
489 | [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest), | |
490 | [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify), | |
491 | [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify), | |
492 | [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo), | |
493 | }; | |
494 | ||
495 | /* track caller id inside control connection, call expect_related */ | |
496 | static int | |
3db05fea | 497 | conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
498 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
499 | ||
500 | { | |
501 | int dir = CTINFO2DIR(ctinfo); | |
9ddd0ed0 JE |
502 | const struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; |
503 | const struct tcphdr *tcph; | |
504 | struct tcphdr _tcph; | |
505 | const struct pptp_pkt_hdr *pptph; | |
506 | struct pptp_pkt_hdr _pptph; | |
f09943fe PM |
507 | struct PptpControlHeader _ctlh, *ctlh; |
508 | union pptp_ctrl_union _pptpReq, *pptpReq; | |
3db05fea | 509 | unsigned int tcplen = skb->len - protoff; |
f09943fe PM |
510 | unsigned int datalen, reqlen, nexthdr_off; |
511 | int oldsstate, oldcstate; | |
512 | int ret; | |
513 | u_int16_t msg; | |
514 | ||
515 | /* don't do any tracking before tcp handshake complete */ | |
516 | if (ctinfo != IP_CT_ESTABLISHED && | |
517 | ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) | |
518 | return NF_ACCEPT; | |
519 | ||
520 | nexthdr_off = protoff; | |
3db05fea | 521 | tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph); |
f09943fe PM |
522 | BUG_ON(!tcph); |
523 | nexthdr_off += tcph->doff * 4; | |
601e68e1 | 524 | datalen = tcplen - tcph->doff * 4; |
f09943fe | 525 | |
3db05fea | 526 | pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph); |
f09943fe | 527 | if (!pptph) { |
0d53778e | 528 | pr_debug("no full PPTP header, can't track\n"); |
f09943fe PM |
529 | return NF_ACCEPT; |
530 | } | |
531 | nexthdr_off += sizeof(_pptph); | |
532 | datalen -= sizeof(_pptph); | |
533 | ||
534 | /* if it's not a control message we can't do anything with it */ | |
535 | if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL || | |
536 | ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) { | |
0d53778e | 537 | pr_debug("not a control packet\n"); |
f09943fe PM |
538 | return NF_ACCEPT; |
539 | } | |
540 | ||
3db05fea | 541 | ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh); |
f09943fe PM |
542 | if (!ctlh) |
543 | return NF_ACCEPT; | |
544 | nexthdr_off += sizeof(_ctlh); | |
545 | datalen -= sizeof(_ctlh); | |
546 | ||
547 | reqlen = datalen; | |
548 | msg = ntohs(ctlh->messageType); | |
549 | if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg]) | |
550 | return NF_ACCEPT; | |
551 | if (reqlen > sizeof(*pptpReq)) | |
552 | reqlen = sizeof(*pptpReq); | |
553 | ||
3db05fea | 554 | pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq); |
f09943fe PM |
555 | if (!pptpReq) |
556 | return NF_ACCEPT; | |
557 | ||
558 | oldsstate = info->sstate; | |
559 | oldcstate = info->cstate; | |
560 | ||
561 | spin_lock_bh(&nf_pptp_lock); | |
562 | ||
563 | /* FIXME: We just blindly assume that the control connection is always | |
564 | * established from PNS->PAC. However, RFC makes no guarantee */ | |
565 | if (dir == IP_CT_DIR_ORIGINAL) | |
566 | /* client -> server (PNS -> PAC) */ | |
3db05fea | 567 | ret = pptp_outbound_pkt(skb, ctlh, pptpReq, reqlen, ct, |
f09943fe PM |
568 | ctinfo); |
569 | else | |
570 | /* server -> client (PAC -> PNS) */ | |
3db05fea | 571 | ret = pptp_inbound_pkt(skb, ctlh, pptpReq, reqlen, ct, |
f09943fe | 572 | ctinfo); |
0d53778e PM |
573 | pr_debug("sstate: %d->%d, cstate: %d->%d\n", |
574 | oldsstate, info->sstate, oldcstate, info->cstate); | |
f09943fe PM |
575 | spin_unlock_bh(&nf_pptp_lock); |
576 | ||
577 | return ret; | |
578 | } | |
579 | ||
6002f266 PM |
580 | static const struct nf_conntrack_expect_policy pptp_exp_policy = { |
581 | .max_expected = 2, | |
582 | .timeout = 5 * 60, | |
583 | }; | |
584 | ||
f09943fe PM |
585 | /* control protocol helper */ |
586 | static struct nf_conntrack_helper pptp __read_mostly = { | |
587 | .name = "pptp", | |
588 | .me = THIS_MODULE, | |
f09943fe PM |
589 | .tuple.src.l3num = AF_INET, |
590 | .tuple.src.u.tcp.port = __constant_htons(PPTP_CONTROL_PORT), | |
591 | .tuple.dst.protonum = IPPROTO_TCP, | |
f09943fe PM |
592 | .help = conntrack_pptp_help, |
593 | .destroy = pptp_destroy_siblings, | |
6002f266 | 594 | .expect_policy = &pptp_exp_policy, |
f09943fe PM |
595 | }; |
596 | ||
597 | static int __init nf_conntrack_pptp_init(void) | |
598 | { | |
599 | return nf_conntrack_helper_register(&pptp); | |
600 | } | |
601 | ||
602 | static void __exit nf_conntrack_pptp_fini(void) | |
603 | { | |
604 | nf_conntrack_helper_unregister(&pptp); | |
605 | nf_ct_gre_keymap_flush(); | |
606 | } | |
607 | ||
608 | module_init(nf_conntrack_pptp_init); | |
609 | module_exit(nf_conntrack_pptp_fini); |