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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 | * | |
f229f6ce PM |
14 | * (C) 2006-2012 Patrick McHardy <kaber@trash.net> |
15 | * | |
f09943fe PM |
16 | * Limitations: |
17 | * - We blindly assume that control connections are always | |
18 | * established in PNS->PAC direction. This is a violation | |
38124328 | 19 | * of RFC 2637 |
f09943fe PM |
20 | * - We can only support one single call within each session |
21 | * TODO: | |
22 | * - testing of incoming PPTP calls | |
23 | */ | |
24 | ||
25 | #include <linux/module.h> | |
26 | #include <linux/skbuff.h> | |
27 | #include <linux/in.h> | |
28 | #include <linux/tcp.h> | |
29 | ||
30 | #include <net/netfilter/nf_conntrack.h> | |
31 | #include <net/netfilter/nf_conntrack_core.h> | |
32 | #include <net/netfilter/nf_conntrack_helper.h> | |
5d0aa2cc | 33 | #include <net/netfilter/nf_conntrack_zones.h> |
f09943fe PM |
34 | #include <linux/netfilter/nf_conntrack_proto_gre.h> |
35 | #include <linux/netfilter/nf_conntrack_pptp.h> | |
36 | ||
37 | #define NF_CT_PPTP_VERSION "3.1" | |
38 | ||
39 | MODULE_LICENSE("GPL"); | |
40 | MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); | |
41 | MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP"); | |
42 | MODULE_ALIAS("ip_conntrack_pptp"); | |
4dc06f96 | 43 | MODULE_ALIAS_NFCT_HELPER("pptp"); |
f09943fe PM |
44 | |
45 | static DEFINE_SPINLOCK(nf_pptp_lock); | |
46 | ||
47 | int | |
3db05fea | 48 | (*nf_nat_pptp_hook_outbound)(struct sk_buff *skb, |
f09943fe | 49 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
051966c0 | 50 | unsigned int protoff, struct PptpControlHeader *ctlh, |
f09943fe PM |
51 | union pptp_ctrl_union *pptpReq) __read_mostly; |
52 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_outbound); | |
53 | ||
54 | int | |
3db05fea | 55 | (*nf_nat_pptp_hook_inbound)(struct sk_buff *skb, |
f09943fe | 56 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
051966c0 | 57 | unsigned int protoff, struct PptpControlHeader *ctlh, |
f09943fe PM |
58 | union pptp_ctrl_union *pptpReq) __read_mostly; |
59 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_inbound); | |
60 | ||
61 | void | |
62 | (*nf_nat_pptp_hook_exp_gre)(struct nf_conntrack_expect *expect_orig, | |
63 | struct nf_conntrack_expect *expect_reply) | |
64 | __read_mostly; | |
65 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_exp_gre); | |
66 | ||
67 | void | |
68 | (*nf_nat_pptp_hook_expectfn)(struct nf_conn *ct, | |
69 | struct nf_conntrack_expect *exp) __read_mostly; | |
70 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn); | |
71 | ||
e9d376f0 | 72 | #if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG) |
f09943fe | 73 | /* PptpControlMessageType names */ |
9ddd0ed0 | 74 | const char *const pptp_msg_name[] = { |
f09943fe PM |
75 | "UNKNOWN_MESSAGE", |
76 | "START_SESSION_REQUEST", | |
77 | "START_SESSION_REPLY", | |
78 | "STOP_SESSION_REQUEST", | |
79 | "STOP_SESSION_REPLY", | |
80 | "ECHO_REQUEST", | |
81 | "ECHO_REPLY", | |
82 | "OUT_CALL_REQUEST", | |
83 | "OUT_CALL_REPLY", | |
84 | "IN_CALL_REQUEST", | |
85 | "IN_CALL_REPLY", | |
86 | "IN_CALL_CONNECT", | |
87 | "CALL_CLEAR_REQUEST", | |
88 | "CALL_DISCONNECT_NOTIFY", | |
89 | "WAN_ERROR_NOTIFY", | |
90 | "SET_LINK_INFO" | |
91 | }; | |
92 | EXPORT_SYMBOL(pptp_msg_name); | |
f09943fe PM |
93 | #endif |
94 | ||
95 | #define SECS *HZ | |
96 | #define MINS * 60 SECS | |
97 | #define HOURS * 60 MINS | |
98 | ||
99 | #define PPTP_GRE_TIMEOUT (10 MINS) | |
100 | #define PPTP_GRE_STREAM_TIMEOUT (5 HOURS) | |
101 | ||
102 | static void pptp_expectfn(struct nf_conn *ct, | |
103 | struct nf_conntrack_expect *exp) | |
104 | { | |
0e6e75af | 105 | struct net *net = nf_ct_net(ct); |
f09943fe | 106 | typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn; |
0d53778e | 107 | pr_debug("increasing timeouts\n"); |
f09943fe PM |
108 | |
109 | /* increase timeout of GRE data channel conntrack entry */ | |
110 | ct->proto.gre.timeout = PPTP_GRE_TIMEOUT; | |
111 | ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT; | |
112 | ||
113 | /* Can you see how rusty this code is, compared with the pre-2.6.11 | |
114 | * one? That's what happened to my shiny newnat of 2002 ;( -HW */ | |
115 | ||
116 | rcu_read_lock(); | |
117 | nf_nat_pptp_expectfn = rcu_dereference(nf_nat_pptp_hook_expectfn); | |
7399072a | 118 | if (nf_nat_pptp_expectfn && ct->master->status & IPS_NAT_MASK) |
f09943fe PM |
119 | nf_nat_pptp_expectfn(ct, exp); |
120 | else { | |
121 | struct nf_conntrack_tuple inv_t; | |
122 | struct nf_conntrack_expect *exp_other; | |
123 | ||
124 | /* obviously this tuple inversion only works until you do NAT */ | |
125 | nf_ct_invert_tuplepr(&inv_t, &exp->tuple); | |
0d53778e | 126 | pr_debug("trying to unexpect other dir: "); |
3c9fba65 | 127 | nf_ct_dump_tuple(&inv_t); |
f09943fe | 128 | |
5d0aa2cc | 129 | exp_other = nf_ct_expect_find_get(net, nf_ct_zone(ct), &inv_t); |
f09943fe PM |
130 | if (exp_other) { |
131 | /* delete other expectation. */ | |
0d53778e | 132 | pr_debug("found\n"); |
6823645d PM |
133 | nf_ct_unexpect_related(exp_other); |
134 | nf_ct_expect_put(exp_other); | |
f09943fe | 135 | } else { |
0d53778e | 136 | pr_debug("not found\n"); |
f09943fe PM |
137 | } |
138 | } | |
139 | rcu_read_unlock(); | |
140 | } | |
141 | ||
5d0aa2cc | 142 | static int destroy_sibling_or_exp(struct net *net, struct nf_conn *ct, |
0e6e75af | 143 | const struct nf_conntrack_tuple *t) |
f09943fe | 144 | { |
9ddd0ed0 | 145 | const struct nf_conntrack_tuple_hash *h; |
308ac914 | 146 | const struct nf_conntrack_zone *zone; |
f09943fe PM |
147 | struct nf_conntrack_expect *exp; |
148 | struct nf_conn *sibling; | |
149 | ||
0d53778e | 150 | pr_debug("trying to timeout ct or exp for tuple "); |
3c9fba65 | 151 | nf_ct_dump_tuple(t); |
f09943fe | 152 | |
308ac914 | 153 | zone = nf_ct_zone(ct); |
5d0aa2cc | 154 | h = nf_conntrack_find_get(net, zone, t); |
f09943fe PM |
155 | if (h) { |
156 | sibling = nf_ct_tuplehash_to_ctrack(h); | |
0d53778e | 157 | pr_debug("setting timeout of conntrack %p to 0\n", sibling); |
f09943fe PM |
158 | sibling->proto.gre.timeout = 0; |
159 | sibling->proto.gre.stream_timeout = 0; | |
160 | if (del_timer(&sibling->timeout)) | |
161 | sibling->timeout.function((unsigned long)sibling); | |
162 | nf_ct_put(sibling); | |
163 | return 1; | |
164 | } else { | |
5d0aa2cc | 165 | exp = nf_ct_expect_find_get(net, zone, t); |
f09943fe | 166 | if (exp) { |
0d53778e | 167 | pr_debug("unexpect_related of expect %p\n", exp); |
6823645d PM |
168 | nf_ct_unexpect_related(exp); |
169 | nf_ct_expect_put(exp); | |
f09943fe PM |
170 | return 1; |
171 | } | |
172 | } | |
173 | return 0; | |
174 | } | |
175 | ||
176 | /* timeout GRE data connections */ | |
177 | static void pptp_destroy_siblings(struct nf_conn *ct) | |
178 | { | |
0e6e75af | 179 | struct net *net = nf_ct_net(ct); |
1afc5679 | 180 | const struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct); |
f09943fe PM |
181 | struct nf_conntrack_tuple t; |
182 | ||
183 | nf_ct_gre_keymap_destroy(ct); | |
184 | ||
185 | /* try original (pns->pac) tuple */ | |
186 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t)); | |
187 | t.dst.protonum = IPPROTO_GRE; | |
1afc5679 PNA |
188 | t.src.u.gre.key = ct_pptp_info->pns_call_id; |
189 | t.dst.u.gre.key = ct_pptp_info->pac_call_id; | |
5d0aa2cc | 190 | if (!destroy_sibling_or_exp(net, ct, &t)) |
0d53778e | 191 | pr_debug("failed to timeout original pns->pac ct/exp\n"); |
f09943fe PM |
192 | |
193 | /* try reply (pac->pns) tuple */ | |
194 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t)); | |
195 | t.dst.protonum = IPPROTO_GRE; | |
1afc5679 PNA |
196 | t.src.u.gre.key = ct_pptp_info->pac_call_id; |
197 | t.dst.u.gre.key = ct_pptp_info->pns_call_id; | |
5d0aa2cc | 198 | if (!destroy_sibling_or_exp(net, ct, &t)) |
0d53778e | 199 | pr_debug("failed to timeout reply pac->pns ct/exp\n"); |
f09943fe PM |
200 | } |
201 | ||
202 | /* expect GRE connections (PNS->PAC and PAC->PNS direction) */ | |
203 | static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid) | |
204 | { | |
205 | struct nf_conntrack_expect *exp_orig, *exp_reply; | |
206 | enum ip_conntrack_dir dir; | |
207 | int ret = 1; | |
208 | typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre; | |
209 | ||
6823645d | 210 | exp_orig = nf_ct_expect_alloc(ct); |
f09943fe PM |
211 | if (exp_orig == NULL) |
212 | goto out; | |
213 | ||
6823645d | 214 | exp_reply = nf_ct_expect_alloc(ct); |
f09943fe PM |
215 | if (exp_reply == NULL) |
216 | goto out_put_orig; | |
217 | ||
218 | /* original direction, PNS->PAC */ | |
219 | dir = IP_CT_DIR_ORIGINAL; | |
6002f266 | 220 | nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT, |
5e8fbe2a | 221 | nf_ct_l3num(ct), |
6823645d PM |
222 | &ct->tuplehash[dir].tuple.src.u3, |
223 | &ct->tuplehash[dir].tuple.dst.u3, | |
224 | IPPROTO_GRE, &peer_callid, &callid); | |
f09943fe PM |
225 | exp_orig->expectfn = pptp_expectfn; |
226 | ||
227 | /* reply direction, PAC->PNS */ | |
228 | dir = IP_CT_DIR_REPLY; | |
6002f266 | 229 | nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT, |
5e8fbe2a | 230 | nf_ct_l3num(ct), |
6823645d PM |
231 | &ct->tuplehash[dir].tuple.src.u3, |
232 | &ct->tuplehash[dir].tuple.dst.u3, | |
233 | IPPROTO_GRE, &callid, &peer_callid); | |
f09943fe PM |
234 | exp_reply->expectfn = pptp_expectfn; |
235 | ||
236 | nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre); | |
237 | if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK) | |
238 | nf_nat_pptp_exp_gre(exp_orig, exp_reply); | |
6823645d | 239 | if (nf_ct_expect_related(exp_orig) != 0) |
f09943fe | 240 | goto out_put_both; |
6823645d | 241 | if (nf_ct_expect_related(exp_reply) != 0) |
f09943fe PM |
242 | goto out_unexpect_orig; |
243 | ||
244 | /* Add GRE keymap entries */ | |
245 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0) | |
246 | goto out_unexpect_both; | |
247 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) { | |
248 | nf_ct_gre_keymap_destroy(ct); | |
249 | goto out_unexpect_both; | |
250 | } | |
251 | ret = 0; | |
252 | ||
253 | out_put_both: | |
6823645d | 254 | nf_ct_expect_put(exp_reply); |
f09943fe | 255 | out_put_orig: |
6823645d | 256 | nf_ct_expect_put(exp_orig); |
f09943fe PM |
257 | out: |
258 | return ret; | |
259 | ||
260 | out_unexpect_both: | |
6823645d | 261 | nf_ct_unexpect_related(exp_reply); |
f09943fe | 262 | out_unexpect_orig: |
6823645d | 263 | nf_ct_unexpect_related(exp_orig); |
f09943fe PM |
264 | goto out_put_both; |
265 | } | |
266 | ||
267 | static inline int | |
051966c0 | 268 | pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
269 | struct PptpControlHeader *ctlh, |
270 | union pptp_ctrl_union *pptpReq, | |
271 | unsigned int reqlen, | |
272 | struct nf_conn *ct, | |
273 | enum ip_conntrack_info ctinfo) | |
274 | { | |
1afc5679 | 275 | struct nf_ct_pptp_master *info = nfct_help_data(ct); |
f09943fe PM |
276 | u_int16_t msg; |
277 | __be16 cid = 0, pcid = 0; | |
278 | typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound; | |
279 | ||
280 | msg = ntohs(ctlh->messageType); | |
0d53778e | 281 | pr_debug("inbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
282 | |
283 | switch (msg) { | |
284 | case PPTP_START_SESSION_REPLY: | |
285 | /* server confirms new control session */ | |
286 | if (info->sstate < PPTP_SESSION_REQUESTED) | |
287 | goto invalid; | |
288 | if (pptpReq->srep.resultCode == PPTP_START_OK) | |
289 | info->sstate = PPTP_SESSION_CONFIRMED; | |
290 | else | |
291 | info->sstate = PPTP_SESSION_ERROR; | |
292 | break; | |
293 | ||
294 | case PPTP_STOP_SESSION_REPLY: | |
295 | /* server confirms end of control session */ | |
296 | if (info->sstate > PPTP_SESSION_STOPREQ) | |
297 | goto invalid; | |
298 | if (pptpReq->strep.resultCode == PPTP_STOP_OK) | |
299 | info->sstate = PPTP_SESSION_NONE; | |
300 | else | |
301 | info->sstate = PPTP_SESSION_ERROR; | |
302 | break; | |
303 | ||
304 | case PPTP_OUT_CALL_REPLY: | |
305 | /* server accepted call, we now expect GRE frames */ | |
306 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
307 | goto invalid; | |
308 | if (info->cstate != PPTP_CALL_OUT_REQ && | |
309 | info->cstate != PPTP_CALL_OUT_CONF) | |
310 | goto invalid; | |
311 | ||
312 | cid = pptpReq->ocack.callID; | |
313 | pcid = pptpReq->ocack.peersCallID; | |
314 | if (info->pns_call_id != pcid) | |
315 | goto invalid; | |
0d53778e PM |
316 | pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], |
317 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
318 | |
319 | if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) { | |
320 | info->cstate = PPTP_CALL_OUT_CONF; | |
321 | info->pac_call_id = cid; | |
322 | exp_gre(ct, cid, pcid); | |
323 | } else | |
324 | info->cstate = PPTP_CALL_NONE; | |
325 | break; | |
326 | ||
327 | case PPTP_IN_CALL_REQUEST: | |
328 | /* server tells us about incoming call request */ | |
329 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
330 | goto invalid; | |
331 | ||
332 | cid = pptpReq->icreq.callID; | |
0d53778e | 333 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
334 | info->cstate = PPTP_CALL_IN_REQ; |
335 | info->pac_call_id = cid; | |
336 | break; | |
337 | ||
338 | case PPTP_IN_CALL_CONNECT: | |
339 | /* server tells us about incoming call established */ | |
340 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
341 | goto invalid; | |
342 | if (info->cstate != PPTP_CALL_IN_REP && | |
343 | info->cstate != PPTP_CALL_IN_CONF) | |
344 | goto invalid; | |
345 | ||
346 | pcid = pptpReq->iccon.peersCallID; | |
347 | cid = info->pac_call_id; | |
348 | ||
349 | if (info->pns_call_id != pcid) | |
350 | goto invalid; | |
351 | ||
0d53778e | 352 | pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid)); |
f09943fe PM |
353 | info->cstate = PPTP_CALL_IN_CONF; |
354 | ||
355 | /* we expect a GRE connection from PAC to PNS */ | |
356 | exp_gre(ct, cid, pcid); | |
357 | break; | |
358 | ||
359 | case PPTP_CALL_DISCONNECT_NOTIFY: | |
360 | /* server confirms disconnect */ | |
361 | cid = pptpReq->disc.callID; | |
0d53778e | 362 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
363 | info->cstate = PPTP_CALL_NONE; |
364 | ||
365 | /* untrack this call id, unexpect GRE packets */ | |
366 | pptp_destroy_siblings(ct); | |
367 | break; | |
368 | ||
369 | case PPTP_WAN_ERROR_NOTIFY: | |
4c6e4209 | 370 | case PPTP_SET_LINK_INFO: |
f09943fe PM |
371 | case PPTP_ECHO_REQUEST: |
372 | case PPTP_ECHO_REPLY: | |
373 | /* I don't have to explain these ;) */ | |
374 | break; | |
375 | ||
376 | default: | |
377 | goto invalid; | |
378 | } | |
379 | ||
380 | nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound); | |
381 | if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK) | |
051966c0 PM |
382 | return nf_nat_pptp_inbound(skb, ct, ctinfo, |
383 | protoff, ctlh, pptpReq); | |
f09943fe PM |
384 | return NF_ACCEPT; |
385 | ||
386 | invalid: | |
0d53778e PM |
387 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
388 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
389 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
390 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
391 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
392 | return NF_ACCEPT; |
393 | } | |
394 | ||
395 | static inline int | |
051966c0 | 396 | pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
397 | struct PptpControlHeader *ctlh, |
398 | union pptp_ctrl_union *pptpReq, | |
399 | unsigned int reqlen, | |
400 | struct nf_conn *ct, | |
401 | enum ip_conntrack_info ctinfo) | |
402 | { | |
1afc5679 | 403 | struct nf_ct_pptp_master *info = nfct_help_data(ct); |
f09943fe PM |
404 | u_int16_t msg; |
405 | __be16 cid = 0, pcid = 0; | |
406 | typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound; | |
407 | ||
408 | msg = ntohs(ctlh->messageType); | |
0d53778e | 409 | pr_debug("outbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
410 | |
411 | switch (msg) { | |
412 | case PPTP_START_SESSION_REQUEST: | |
413 | /* client requests for new control session */ | |
414 | if (info->sstate != PPTP_SESSION_NONE) | |
415 | goto invalid; | |
416 | info->sstate = PPTP_SESSION_REQUESTED; | |
417 | break; | |
418 | ||
419 | case PPTP_STOP_SESSION_REQUEST: | |
420 | /* client requests end of control session */ | |
421 | info->sstate = PPTP_SESSION_STOPREQ; | |
422 | break; | |
423 | ||
424 | case PPTP_OUT_CALL_REQUEST: | |
425 | /* client initiating connection to server */ | |
426 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
427 | goto invalid; | |
428 | info->cstate = PPTP_CALL_OUT_REQ; | |
429 | /* track PNS call id */ | |
430 | cid = pptpReq->ocreq.callID; | |
0d53778e | 431 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
432 | info->pns_call_id = cid; |
433 | break; | |
434 | ||
435 | case PPTP_IN_CALL_REPLY: | |
436 | /* client answers incoming call */ | |
437 | if (info->cstate != PPTP_CALL_IN_REQ && | |
438 | info->cstate != PPTP_CALL_IN_REP) | |
439 | goto invalid; | |
440 | ||
441 | cid = pptpReq->icack.callID; | |
442 | pcid = pptpReq->icack.peersCallID; | |
443 | if (info->pac_call_id != pcid) | |
444 | goto invalid; | |
0d53778e PM |
445 | pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg], |
446 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
447 | |
448 | if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) { | |
449 | /* part two of the three-way handshake */ | |
450 | info->cstate = PPTP_CALL_IN_REP; | |
451 | info->pns_call_id = cid; | |
452 | } else | |
453 | info->cstate = PPTP_CALL_NONE; | |
454 | break; | |
455 | ||
456 | case PPTP_CALL_CLEAR_REQUEST: | |
457 | /* client requests hangup of call */ | |
458 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
459 | goto invalid; | |
460 | /* FUTURE: iterate over all calls and check if | |
461 | * call ID is valid. We don't do this without newnat, | |
462 | * because we only know about last call */ | |
463 | info->cstate = PPTP_CALL_CLEAR_REQ; | |
464 | break; | |
465 | ||
466 | case PPTP_SET_LINK_INFO: | |
467 | case PPTP_ECHO_REQUEST: | |
468 | case PPTP_ECHO_REPLY: | |
469 | /* I don't have to explain these ;) */ | |
470 | break; | |
471 | ||
472 | default: | |
473 | goto invalid; | |
474 | } | |
475 | ||
476 | nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound); | |
477 | if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK) | |
051966c0 PM |
478 | return nf_nat_pptp_outbound(skb, ct, ctinfo, |
479 | protoff, ctlh, pptpReq); | |
f09943fe PM |
480 | return NF_ACCEPT; |
481 | ||
482 | invalid: | |
0d53778e PM |
483 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
484 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
485 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
486 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
487 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
488 | return NF_ACCEPT; |
489 | } | |
490 | ||
491 | static const unsigned int pptp_msg_size[] = { | |
492 | [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest), | |
493 | [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply), | |
494 | [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest), | |
495 | [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply), | |
496 | [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest), | |
497 | [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply), | |
498 | [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest), | |
499 | [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply), | |
500 | [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected), | |
501 | [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest), | |
502 | [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify), | |
503 | [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify), | |
504 | [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo), | |
505 | }; | |
506 | ||
507 | /* track caller id inside control connection, call expect_related */ | |
508 | static int | |
3db05fea | 509 | conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
510 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
511 | ||
512 | { | |
513 | int dir = CTINFO2DIR(ctinfo); | |
1afc5679 | 514 | const struct nf_ct_pptp_master *info = nfct_help_data(ct); |
9ddd0ed0 JE |
515 | const struct tcphdr *tcph; |
516 | struct tcphdr _tcph; | |
517 | const struct pptp_pkt_hdr *pptph; | |
518 | struct pptp_pkt_hdr _pptph; | |
f09943fe PM |
519 | struct PptpControlHeader _ctlh, *ctlh; |
520 | union pptp_ctrl_union _pptpReq, *pptpReq; | |
3db05fea | 521 | unsigned int tcplen = skb->len - protoff; |
f09943fe PM |
522 | unsigned int datalen, reqlen, nexthdr_off; |
523 | int oldsstate, oldcstate; | |
524 | int ret; | |
525 | u_int16_t msg; | |
526 | ||
527 | /* don't do any tracking before tcp handshake complete */ | |
fb048833 | 528 | if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY) |
f09943fe PM |
529 | return NF_ACCEPT; |
530 | ||
531 | nexthdr_off = protoff; | |
3db05fea | 532 | tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph); |
f09943fe PM |
533 | BUG_ON(!tcph); |
534 | nexthdr_off += tcph->doff * 4; | |
601e68e1 | 535 | datalen = tcplen - tcph->doff * 4; |
f09943fe | 536 | |
3db05fea | 537 | pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph); |
f09943fe | 538 | if (!pptph) { |
0d53778e | 539 | pr_debug("no full PPTP header, can't track\n"); |
f09943fe PM |
540 | return NF_ACCEPT; |
541 | } | |
542 | nexthdr_off += sizeof(_pptph); | |
543 | datalen -= sizeof(_pptph); | |
544 | ||
545 | /* if it's not a control message we can't do anything with it */ | |
546 | if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL || | |
547 | ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) { | |
0d53778e | 548 | pr_debug("not a control packet\n"); |
f09943fe PM |
549 | return NF_ACCEPT; |
550 | } | |
551 | ||
3db05fea | 552 | ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh); |
f09943fe PM |
553 | if (!ctlh) |
554 | return NF_ACCEPT; | |
555 | nexthdr_off += sizeof(_ctlh); | |
556 | datalen -= sizeof(_ctlh); | |
557 | ||
558 | reqlen = datalen; | |
559 | msg = ntohs(ctlh->messageType); | |
560 | if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg]) | |
561 | return NF_ACCEPT; | |
562 | if (reqlen > sizeof(*pptpReq)) | |
563 | reqlen = sizeof(*pptpReq); | |
564 | ||
3db05fea | 565 | pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq); |
f09943fe PM |
566 | if (!pptpReq) |
567 | return NF_ACCEPT; | |
568 | ||
569 | oldsstate = info->sstate; | |
570 | oldcstate = info->cstate; | |
571 | ||
572 | spin_lock_bh(&nf_pptp_lock); | |
573 | ||
574 | /* FIXME: We just blindly assume that the control connection is always | |
575 | * established from PNS->PAC. However, RFC makes no guarantee */ | |
576 | if (dir == IP_CT_DIR_ORIGINAL) | |
577 | /* client -> server (PNS -> PAC) */ | |
051966c0 | 578 | ret = pptp_outbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct, |
f09943fe PM |
579 | ctinfo); |
580 | else | |
581 | /* server -> client (PAC -> PNS) */ | |
051966c0 | 582 | ret = pptp_inbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct, |
f09943fe | 583 | ctinfo); |
0d53778e PM |
584 | pr_debug("sstate: %d->%d, cstate: %d->%d\n", |
585 | oldsstate, info->sstate, oldcstate, info->cstate); | |
f09943fe PM |
586 | spin_unlock_bh(&nf_pptp_lock); |
587 | ||
588 | return ret; | |
589 | } | |
590 | ||
6002f266 PM |
591 | static const struct nf_conntrack_expect_policy pptp_exp_policy = { |
592 | .max_expected = 2, | |
593 | .timeout = 5 * 60, | |
594 | }; | |
595 | ||
f09943fe PM |
596 | /* control protocol helper */ |
597 | static struct nf_conntrack_helper pptp __read_mostly = { | |
598 | .name = "pptp", | |
599 | .me = THIS_MODULE, | |
1afc5679 | 600 | .data_len = sizeof(struct nf_ct_pptp_master), |
f09943fe | 601 | .tuple.src.l3num = AF_INET, |
09640e63 | 602 | .tuple.src.u.tcp.port = cpu_to_be16(PPTP_CONTROL_PORT), |
f09943fe | 603 | .tuple.dst.protonum = IPPROTO_TCP, |
f09943fe PM |
604 | .help = conntrack_pptp_help, |
605 | .destroy = pptp_destroy_siblings, | |
6002f266 | 606 | .expect_policy = &pptp_exp_policy, |
f09943fe PM |
607 | }; |
608 | ||
609 | static int __init nf_conntrack_pptp_init(void) | |
610 | { | |
8142b227 | 611 | return nf_conntrack_helper_register(&pptp); |
f09943fe PM |
612 | } |
613 | ||
614 | static void __exit nf_conntrack_pptp_fini(void) | |
615 | { | |
616 | nf_conntrack_helper_unregister(&pptp); | |
f09943fe PM |
617 | } |
618 | ||
619 | module_init(nf_conntrack_pptp_init); | |
620 | module_exit(nf_conntrack_pptp_fini); |