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 | ||
346e15be | 68 | #if defined(DEBUG) || defined(CONFIG_DYNAMIC_PRINTK_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 | { | |
0e6e75af | 101 | struct net *net = nf_ct_net(ct); |
f09943fe | 102 | typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn; |
0d53778e | 103 | pr_debug("increasing timeouts\n"); |
f09943fe PM |
104 | |
105 | /* increase timeout of GRE data channel conntrack entry */ | |
106 | ct->proto.gre.timeout = PPTP_GRE_TIMEOUT; | |
107 | ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT; | |
108 | ||
109 | /* Can you see how rusty this code is, compared with the pre-2.6.11 | |
110 | * one? That's what happened to my shiny newnat of 2002 ;( -HW */ | |
111 | ||
112 | rcu_read_lock(); | |
113 | nf_nat_pptp_expectfn = rcu_dereference(nf_nat_pptp_hook_expectfn); | |
7399072a | 114 | if (nf_nat_pptp_expectfn && ct->master->status & IPS_NAT_MASK) |
f09943fe PM |
115 | nf_nat_pptp_expectfn(ct, exp); |
116 | else { | |
117 | struct nf_conntrack_tuple inv_t; | |
118 | struct nf_conntrack_expect *exp_other; | |
119 | ||
120 | /* obviously this tuple inversion only works until you do NAT */ | |
121 | nf_ct_invert_tuplepr(&inv_t, &exp->tuple); | |
0d53778e | 122 | pr_debug("trying to unexpect other dir: "); |
3c9fba65 | 123 | nf_ct_dump_tuple(&inv_t); |
f09943fe | 124 | |
0e6e75af | 125 | exp_other = nf_ct_expect_find_get(net, &inv_t); |
f09943fe PM |
126 | if (exp_other) { |
127 | /* delete other expectation. */ | |
0d53778e | 128 | pr_debug("found\n"); |
6823645d PM |
129 | nf_ct_unexpect_related(exp_other); |
130 | nf_ct_expect_put(exp_other); | |
f09943fe | 131 | } else { |
0d53778e | 132 | pr_debug("not found\n"); |
f09943fe PM |
133 | } |
134 | } | |
135 | rcu_read_unlock(); | |
136 | } | |
137 | ||
0e6e75af AD |
138 | static int destroy_sibling_or_exp(struct net *net, |
139 | const struct nf_conntrack_tuple *t) | |
f09943fe | 140 | { |
9ddd0ed0 | 141 | const struct nf_conntrack_tuple_hash *h; |
f09943fe PM |
142 | struct nf_conntrack_expect *exp; |
143 | struct nf_conn *sibling; | |
144 | ||
0d53778e | 145 | pr_debug("trying to timeout ct or exp for tuple "); |
3c9fba65 | 146 | nf_ct_dump_tuple(t); |
f09943fe | 147 | |
0e6e75af | 148 | h = nf_conntrack_find_get(net, t); |
f09943fe PM |
149 | if (h) { |
150 | sibling = nf_ct_tuplehash_to_ctrack(h); | |
0d53778e | 151 | pr_debug("setting timeout of conntrack %p to 0\n", sibling); |
f09943fe PM |
152 | sibling->proto.gre.timeout = 0; |
153 | sibling->proto.gre.stream_timeout = 0; | |
154 | if (del_timer(&sibling->timeout)) | |
155 | sibling->timeout.function((unsigned long)sibling); | |
156 | nf_ct_put(sibling); | |
157 | return 1; | |
158 | } else { | |
0e6e75af | 159 | exp = nf_ct_expect_find_get(net, t); |
f09943fe | 160 | if (exp) { |
0d53778e | 161 | pr_debug("unexpect_related of expect %p\n", exp); |
6823645d PM |
162 | nf_ct_unexpect_related(exp); |
163 | nf_ct_expect_put(exp); | |
f09943fe PM |
164 | return 1; |
165 | } | |
166 | } | |
167 | return 0; | |
168 | } | |
169 | ||
170 | /* timeout GRE data connections */ | |
171 | static void pptp_destroy_siblings(struct nf_conn *ct) | |
172 | { | |
0e6e75af | 173 | struct net *net = nf_ct_net(ct); |
9ddd0ed0 | 174 | const struct nf_conn_help *help = nfct_help(ct); |
f09943fe PM |
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; | |
0e6e75af | 184 | if (!destroy_sibling_or_exp(net, &t)) |
0d53778e | 185 | pr_debug("failed to timeout original pns->pac ct/exp\n"); |
f09943fe PM |
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; | |
0e6e75af | 192 | if (!destroy_sibling_or_exp(net, &t)) |
0d53778e | 193 | pr_debug("failed to timeout reply pac->pns ct/exp\n"); |
f09943fe PM |
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 | ||
6823645d | 204 | exp_orig = nf_ct_expect_alloc(ct); |
f09943fe PM |
205 | if (exp_orig == NULL) |
206 | goto out; | |
207 | ||
6823645d | 208 | exp_reply = nf_ct_expect_alloc(ct); |
f09943fe PM |
209 | if (exp_reply == NULL) |
210 | goto out_put_orig; | |
211 | ||
212 | /* original direction, PNS->PAC */ | |
213 | dir = IP_CT_DIR_ORIGINAL; | |
6002f266 | 214 | nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT, |
5e8fbe2a | 215 | nf_ct_l3num(ct), |
6823645d PM |
216 | &ct->tuplehash[dir].tuple.src.u3, |
217 | &ct->tuplehash[dir].tuple.dst.u3, | |
218 | IPPROTO_GRE, &peer_callid, &callid); | |
f09943fe PM |
219 | exp_orig->expectfn = pptp_expectfn; |
220 | ||
221 | /* reply direction, PAC->PNS */ | |
222 | dir = IP_CT_DIR_REPLY; | |
6002f266 | 223 | nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT, |
5e8fbe2a | 224 | nf_ct_l3num(ct), |
6823645d PM |
225 | &ct->tuplehash[dir].tuple.src.u3, |
226 | &ct->tuplehash[dir].tuple.dst.u3, | |
227 | IPPROTO_GRE, &callid, &peer_callid); | |
f09943fe PM |
228 | exp_reply->expectfn = pptp_expectfn; |
229 | ||
230 | nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre); | |
231 | if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK) | |
232 | nf_nat_pptp_exp_gre(exp_orig, exp_reply); | |
6823645d | 233 | if (nf_ct_expect_related(exp_orig) != 0) |
f09943fe | 234 | goto out_put_both; |
6823645d | 235 | if (nf_ct_expect_related(exp_reply) != 0) |
f09943fe PM |
236 | goto out_unexpect_orig; |
237 | ||
238 | /* Add GRE keymap entries */ | |
239 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0) | |
240 | goto out_unexpect_both; | |
241 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) { | |
242 | nf_ct_gre_keymap_destroy(ct); | |
243 | goto out_unexpect_both; | |
244 | } | |
245 | ret = 0; | |
246 | ||
247 | out_put_both: | |
6823645d | 248 | nf_ct_expect_put(exp_reply); |
f09943fe | 249 | out_put_orig: |
6823645d | 250 | nf_ct_expect_put(exp_orig); |
f09943fe PM |
251 | out: |
252 | return ret; | |
253 | ||
254 | out_unexpect_both: | |
6823645d | 255 | nf_ct_unexpect_related(exp_reply); |
f09943fe | 256 | out_unexpect_orig: |
6823645d | 257 | nf_ct_unexpect_related(exp_orig); |
f09943fe PM |
258 | goto out_put_both; |
259 | } | |
260 | ||
261 | static inline int | |
3db05fea | 262 | pptp_inbound_pkt(struct sk_buff *skb, |
f09943fe PM |
263 | struct PptpControlHeader *ctlh, |
264 | union pptp_ctrl_union *pptpReq, | |
265 | unsigned int reqlen, | |
266 | struct nf_conn *ct, | |
267 | enum ip_conntrack_info ctinfo) | |
268 | { | |
269 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
270 | u_int16_t msg; | |
271 | __be16 cid = 0, pcid = 0; | |
272 | typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound; | |
273 | ||
274 | msg = ntohs(ctlh->messageType); | |
0d53778e | 275 | pr_debug("inbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
276 | |
277 | switch (msg) { | |
278 | case PPTP_START_SESSION_REPLY: | |
279 | /* server confirms new control session */ | |
280 | if (info->sstate < PPTP_SESSION_REQUESTED) | |
281 | goto invalid; | |
282 | if (pptpReq->srep.resultCode == PPTP_START_OK) | |
283 | info->sstate = PPTP_SESSION_CONFIRMED; | |
284 | else | |
285 | info->sstate = PPTP_SESSION_ERROR; | |
286 | break; | |
287 | ||
288 | case PPTP_STOP_SESSION_REPLY: | |
289 | /* server confirms end of control session */ | |
290 | if (info->sstate > PPTP_SESSION_STOPREQ) | |
291 | goto invalid; | |
292 | if (pptpReq->strep.resultCode == PPTP_STOP_OK) | |
293 | info->sstate = PPTP_SESSION_NONE; | |
294 | else | |
295 | info->sstate = PPTP_SESSION_ERROR; | |
296 | break; | |
297 | ||
298 | case PPTP_OUT_CALL_REPLY: | |
299 | /* server accepted call, we now expect GRE frames */ | |
300 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
301 | goto invalid; | |
302 | if (info->cstate != PPTP_CALL_OUT_REQ && | |
303 | info->cstate != PPTP_CALL_OUT_CONF) | |
304 | goto invalid; | |
305 | ||
306 | cid = pptpReq->ocack.callID; | |
307 | pcid = pptpReq->ocack.peersCallID; | |
308 | if (info->pns_call_id != pcid) | |
309 | goto invalid; | |
0d53778e PM |
310 | pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], |
311 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
312 | |
313 | if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) { | |
314 | info->cstate = PPTP_CALL_OUT_CONF; | |
315 | info->pac_call_id = cid; | |
316 | exp_gre(ct, cid, pcid); | |
317 | } else | |
318 | info->cstate = PPTP_CALL_NONE; | |
319 | break; | |
320 | ||
321 | case PPTP_IN_CALL_REQUEST: | |
322 | /* server tells us about incoming call request */ | |
323 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
324 | goto invalid; | |
325 | ||
326 | cid = pptpReq->icreq.callID; | |
0d53778e | 327 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
328 | info->cstate = PPTP_CALL_IN_REQ; |
329 | info->pac_call_id = cid; | |
330 | break; | |
331 | ||
332 | case PPTP_IN_CALL_CONNECT: | |
333 | /* server tells us about incoming call established */ | |
334 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
335 | goto invalid; | |
336 | if (info->cstate != PPTP_CALL_IN_REP && | |
337 | info->cstate != PPTP_CALL_IN_CONF) | |
338 | goto invalid; | |
339 | ||
340 | pcid = pptpReq->iccon.peersCallID; | |
341 | cid = info->pac_call_id; | |
342 | ||
343 | if (info->pns_call_id != pcid) | |
344 | goto invalid; | |
345 | ||
0d53778e | 346 | pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid)); |
f09943fe PM |
347 | info->cstate = PPTP_CALL_IN_CONF; |
348 | ||
349 | /* we expect a GRE connection from PAC to PNS */ | |
350 | exp_gre(ct, cid, pcid); | |
351 | break; | |
352 | ||
353 | case PPTP_CALL_DISCONNECT_NOTIFY: | |
354 | /* server confirms disconnect */ | |
355 | cid = pptpReq->disc.callID; | |
0d53778e | 356 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
357 | info->cstate = PPTP_CALL_NONE; |
358 | ||
359 | /* untrack this call id, unexpect GRE packets */ | |
360 | pptp_destroy_siblings(ct); | |
361 | break; | |
362 | ||
363 | case PPTP_WAN_ERROR_NOTIFY: | |
364 | case PPTP_ECHO_REQUEST: | |
365 | case PPTP_ECHO_REPLY: | |
366 | /* I don't have to explain these ;) */ | |
367 | break; | |
368 | ||
369 | default: | |
370 | goto invalid; | |
371 | } | |
372 | ||
373 | nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound); | |
374 | if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK) | |
3db05fea | 375 | return nf_nat_pptp_inbound(skb, ct, ctinfo, ctlh, pptpReq); |
f09943fe PM |
376 | return NF_ACCEPT; |
377 | ||
378 | invalid: | |
0d53778e PM |
379 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
380 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
381 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
382 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
383 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
384 | return NF_ACCEPT; |
385 | } | |
386 | ||
387 | static inline int | |
3db05fea | 388 | pptp_outbound_pkt(struct sk_buff *skb, |
f09943fe PM |
389 | struct PptpControlHeader *ctlh, |
390 | union pptp_ctrl_union *pptpReq, | |
391 | unsigned int reqlen, | |
392 | struct nf_conn *ct, | |
393 | enum ip_conntrack_info ctinfo) | |
394 | { | |
395 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
396 | u_int16_t msg; | |
397 | __be16 cid = 0, pcid = 0; | |
398 | typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound; | |
399 | ||
400 | msg = ntohs(ctlh->messageType); | |
0d53778e | 401 | pr_debug("outbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
402 | |
403 | switch (msg) { | |
404 | case PPTP_START_SESSION_REQUEST: | |
405 | /* client requests for new control session */ | |
406 | if (info->sstate != PPTP_SESSION_NONE) | |
407 | goto invalid; | |
408 | info->sstate = PPTP_SESSION_REQUESTED; | |
409 | break; | |
410 | ||
411 | case PPTP_STOP_SESSION_REQUEST: | |
412 | /* client requests end of control session */ | |
413 | info->sstate = PPTP_SESSION_STOPREQ; | |
414 | break; | |
415 | ||
416 | case PPTP_OUT_CALL_REQUEST: | |
417 | /* client initiating connection to server */ | |
418 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
419 | goto invalid; | |
420 | info->cstate = PPTP_CALL_OUT_REQ; | |
421 | /* track PNS call id */ | |
422 | cid = pptpReq->ocreq.callID; | |
0d53778e | 423 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
424 | info->pns_call_id = cid; |
425 | break; | |
426 | ||
427 | case PPTP_IN_CALL_REPLY: | |
428 | /* client answers incoming call */ | |
429 | if (info->cstate != PPTP_CALL_IN_REQ && | |
430 | info->cstate != PPTP_CALL_IN_REP) | |
431 | goto invalid; | |
432 | ||
433 | cid = pptpReq->icack.callID; | |
434 | pcid = pptpReq->icack.peersCallID; | |
435 | if (info->pac_call_id != pcid) | |
436 | goto invalid; | |
0d53778e PM |
437 | pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg], |
438 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
439 | |
440 | if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) { | |
441 | /* part two of the three-way handshake */ | |
442 | info->cstate = PPTP_CALL_IN_REP; | |
443 | info->pns_call_id = cid; | |
444 | } else | |
445 | info->cstate = PPTP_CALL_NONE; | |
446 | break; | |
447 | ||
448 | case PPTP_CALL_CLEAR_REQUEST: | |
449 | /* client requests hangup of call */ | |
450 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
451 | goto invalid; | |
452 | /* FUTURE: iterate over all calls and check if | |
453 | * call ID is valid. We don't do this without newnat, | |
454 | * because we only know about last call */ | |
455 | info->cstate = PPTP_CALL_CLEAR_REQ; | |
456 | break; | |
457 | ||
458 | case PPTP_SET_LINK_INFO: | |
459 | case PPTP_ECHO_REQUEST: | |
460 | case PPTP_ECHO_REPLY: | |
461 | /* I don't have to explain these ;) */ | |
462 | break; | |
463 | ||
464 | default: | |
465 | goto invalid; | |
466 | } | |
467 | ||
468 | nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound); | |
469 | if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK) | |
3db05fea | 470 | return nf_nat_pptp_outbound(skb, ct, ctinfo, ctlh, pptpReq); |
f09943fe PM |
471 | return NF_ACCEPT; |
472 | ||
473 | invalid: | |
0d53778e PM |
474 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
475 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
476 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
477 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
478 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
479 | return NF_ACCEPT; |
480 | } | |
481 | ||
482 | static const unsigned int pptp_msg_size[] = { | |
483 | [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest), | |
484 | [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply), | |
485 | [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest), | |
486 | [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply), | |
487 | [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest), | |
488 | [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply), | |
489 | [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest), | |
490 | [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply), | |
491 | [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected), | |
492 | [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest), | |
493 | [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify), | |
494 | [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify), | |
495 | [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo), | |
496 | }; | |
497 | ||
498 | /* track caller id inside control connection, call expect_related */ | |
499 | static int | |
3db05fea | 500 | conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
501 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
502 | ||
503 | { | |
504 | int dir = CTINFO2DIR(ctinfo); | |
9ddd0ed0 JE |
505 | const struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; |
506 | const struct tcphdr *tcph; | |
507 | struct tcphdr _tcph; | |
508 | const struct pptp_pkt_hdr *pptph; | |
509 | struct pptp_pkt_hdr _pptph; | |
f09943fe PM |
510 | struct PptpControlHeader _ctlh, *ctlh; |
511 | union pptp_ctrl_union _pptpReq, *pptpReq; | |
3db05fea | 512 | unsigned int tcplen = skb->len - protoff; |
f09943fe PM |
513 | unsigned int datalen, reqlen, nexthdr_off; |
514 | int oldsstate, oldcstate; | |
515 | int ret; | |
516 | u_int16_t msg; | |
517 | ||
518 | /* don't do any tracking before tcp handshake complete */ | |
519 | if (ctinfo != IP_CT_ESTABLISHED && | |
520 | ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) | |
521 | return NF_ACCEPT; | |
522 | ||
523 | nexthdr_off = protoff; | |
3db05fea | 524 | tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph); |
f09943fe PM |
525 | BUG_ON(!tcph); |
526 | nexthdr_off += tcph->doff * 4; | |
601e68e1 | 527 | datalen = tcplen - tcph->doff * 4; |
f09943fe | 528 | |
3db05fea | 529 | pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph); |
f09943fe | 530 | if (!pptph) { |
0d53778e | 531 | pr_debug("no full PPTP header, can't track\n"); |
f09943fe PM |
532 | return NF_ACCEPT; |
533 | } | |
534 | nexthdr_off += sizeof(_pptph); | |
535 | datalen -= sizeof(_pptph); | |
536 | ||
537 | /* if it's not a control message we can't do anything with it */ | |
538 | if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL || | |
539 | ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) { | |
0d53778e | 540 | pr_debug("not a control packet\n"); |
f09943fe PM |
541 | return NF_ACCEPT; |
542 | } | |
543 | ||
3db05fea | 544 | ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh); |
f09943fe PM |
545 | if (!ctlh) |
546 | return NF_ACCEPT; | |
547 | nexthdr_off += sizeof(_ctlh); | |
548 | datalen -= sizeof(_ctlh); | |
549 | ||
550 | reqlen = datalen; | |
551 | msg = ntohs(ctlh->messageType); | |
552 | if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg]) | |
553 | return NF_ACCEPT; | |
554 | if (reqlen > sizeof(*pptpReq)) | |
555 | reqlen = sizeof(*pptpReq); | |
556 | ||
3db05fea | 557 | pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq); |
f09943fe PM |
558 | if (!pptpReq) |
559 | return NF_ACCEPT; | |
560 | ||
561 | oldsstate = info->sstate; | |
562 | oldcstate = info->cstate; | |
563 | ||
564 | spin_lock_bh(&nf_pptp_lock); | |
565 | ||
566 | /* FIXME: We just blindly assume that the control connection is always | |
567 | * established from PNS->PAC. However, RFC makes no guarantee */ | |
568 | if (dir == IP_CT_DIR_ORIGINAL) | |
569 | /* client -> server (PNS -> PAC) */ | |
3db05fea | 570 | ret = pptp_outbound_pkt(skb, ctlh, pptpReq, reqlen, ct, |
f09943fe PM |
571 | ctinfo); |
572 | else | |
573 | /* server -> client (PAC -> PNS) */ | |
3db05fea | 574 | ret = pptp_inbound_pkt(skb, ctlh, pptpReq, reqlen, ct, |
f09943fe | 575 | ctinfo); |
0d53778e PM |
576 | pr_debug("sstate: %d->%d, cstate: %d->%d\n", |
577 | oldsstate, info->sstate, oldcstate, info->cstate); | |
f09943fe PM |
578 | spin_unlock_bh(&nf_pptp_lock); |
579 | ||
580 | return ret; | |
581 | } | |
582 | ||
6002f266 PM |
583 | static const struct nf_conntrack_expect_policy pptp_exp_policy = { |
584 | .max_expected = 2, | |
585 | .timeout = 5 * 60, | |
586 | }; | |
587 | ||
f09943fe PM |
588 | /* control protocol helper */ |
589 | static struct nf_conntrack_helper pptp __read_mostly = { | |
590 | .name = "pptp", | |
591 | .me = THIS_MODULE, | |
f09943fe PM |
592 | .tuple.src.l3num = AF_INET, |
593 | .tuple.src.u.tcp.port = __constant_htons(PPTP_CONTROL_PORT), | |
594 | .tuple.dst.protonum = IPPROTO_TCP, | |
f09943fe PM |
595 | .help = conntrack_pptp_help, |
596 | .destroy = pptp_destroy_siblings, | |
6002f266 | 597 | .expect_policy = &pptp_exp_policy, |
f09943fe PM |
598 | }; |
599 | ||
0e6e75af AD |
600 | static void nf_conntrack_pptp_net_exit(struct net *net) |
601 | { | |
602 | nf_ct_gre_keymap_flush(net); | |
603 | } | |
604 | ||
605 | static struct pernet_operations nf_conntrack_pptp_net_ops = { | |
606 | .exit = nf_conntrack_pptp_net_exit, | |
607 | }; | |
608 | ||
f09943fe PM |
609 | static int __init nf_conntrack_pptp_init(void) |
610 | { | |
0e6e75af AD |
611 | int rv; |
612 | ||
613 | rv = nf_conntrack_helper_register(&pptp); | |
614 | if (rv < 0) | |
615 | return rv; | |
616 | rv = register_pernet_subsys(&nf_conntrack_pptp_net_ops); | |
617 | if (rv < 0) | |
618 | nf_conntrack_helper_unregister(&pptp); | |
619 | return rv; | |
f09943fe PM |
620 | } |
621 | ||
622 | static void __exit nf_conntrack_pptp_fini(void) | |
623 | { | |
624 | nf_conntrack_helper_unregister(&pptp); | |
0e6e75af | 625 | unregister_pernet_subsys(&nf_conntrack_pptp_net_ops); |
f09943fe PM |
626 | } |
627 | ||
628 | module_init(nf_conntrack_pptp_init); | |
629 | module_exit(nf_conntrack_pptp_fini); |