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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 | ||
f09943fe | 116 | nf_nat_pptp_expectfn = rcu_dereference(nf_nat_pptp_hook_expectfn); |
7399072a | 117 | if (nf_nat_pptp_expectfn && ct->master->status & IPS_NAT_MASK) |
f09943fe PM |
118 | nf_nat_pptp_expectfn(ct, exp); |
119 | else { | |
120 | struct nf_conntrack_tuple inv_t; | |
121 | struct nf_conntrack_expect *exp_other; | |
122 | ||
123 | /* obviously this tuple inversion only works until you do NAT */ | |
124 | nf_ct_invert_tuplepr(&inv_t, &exp->tuple); | |
0d53778e | 125 | pr_debug("trying to unexpect other dir: "); |
3c9fba65 | 126 | nf_ct_dump_tuple(&inv_t); |
f09943fe | 127 | |
5d0aa2cc | 128 | exp_other = nf_ct_expect_find_get(net, nf_ct_zone(ct), &inv_t); |
f09943fe PM |
129 | if (exp_other) { |
130 | /* delete other expectation. */ | |
0d53778e | 131 | pr_debug("found\n"); |
6823645d PM |
132 | nf_ct_unexpect_related(exp_other); |
133 | nf_ct_expect_put(exp_other); | |
f09943fe | 134 | } else { |
0d53778e | 135 | pr_debug("not found\n"); |
f09943fe PM |
136 | } |
137 | } | |
f09943fe PM |
138 | } |
139 | ||
5d0aa2cc | 140 | static int destroy_sibling_or_exp(struct net *net, struct nf_conn *ct, |
0e6e75af | 141 | const struct nf_conntrack_tuple *t) |
f09943fe | 142 | { |
9ddd0ed0 | 143 | const struct nf_conntrack_tuple_hash *h; |
308ac914 | 144 | const struct nf_conntrack_zone *zone; |
f09943fe PM |
145 | struct nf_conntrack_expect *exp; |
146 | struct nf_conn *sibling; | |
147 | ||
0d53778e | 148 | pr_debug("trying to timeout ct or exp for tuple "); |
3c9fba65 | 149 | nf_ct_dump_tuple(t); |
f09943fe | 150 | |
308ac914 | 151 | zone = nf_ct_zone(ct); |
5d0aa2cc | 152 | h = nf_conntrack_find_get(net, zone, t); |
f09943fe PM |
153 | if (h) { |
154 | sibling = nf_ct_tuplehash_to_ctrack(h); | |
0d53778e | 155 | pr_debug("setting timeout of conntrack %p to 0\n", sibling); |
f09943fe PM |
156 | sibling->proto.gre.timeout = 0; |
157 | sibling->proto.gre.stream_timeout = 0; | |
f330a7fd | 158 | nf_ct_kill(sibling); |
f09943fe PM |
159 | nf_ct_put(sibling); |
160 | return 1; | |
161 | } else { | |
5d0aa2cc | 162 | exp = nf_ct_expect_find_get(net, zone, t); |
f09943fe | 163 | if (exp) { |
0d53778e | 164 | pr_debug("unexpect_related of expect %p\n", exp); |
6823645d PM |
165 | nf_ct_unexpect_related(exp); |
166 | nf_ct_expect_put(exp); | |
f09943fe PM |
167 | return 1; |
168 | } | |
169 | } | |
170 | return 0; | |
171 | } | |
172 | ||
173 | /* timeout GRE data connections */ | |
174 | static void pptp_destroy_siblings(struct nf_conn *ct) | |
175 | { | |
0e6e75af | 176 | struct net *net = nf_ct_net(ct); |
1afc5679 | 177 | const struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct); |
f09943fe PM |
178 | struct nf_conntrack_tuple t; |
179 | ||
180 | nf_ct_gre_keymap_destroy(ct); | |
181 | ||
182 | /* try original (pns->pac) tuple */ | |
183 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t)); | |
184 | t.dst.protonum = IPPROTO_GRE; | |
1afc5679 PNA |
185 | t.src.u.gre.key = ct_pptp_info->pns_call_id; |
186 | t.dst.u.gre.key = ct_pptp_info->pac_call_id; | |
5d0aa2cc | 187 | if (!destroy_sibling_or_exp(net, ct, &t)) |
0d53778e | 188 | pr_debug("failed to timeout original pns->pac ct/exp\n"); |
f09943fe PM |
189 | |
190 | /* try reply (pac->pns) tuple */ | |
191 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t)); | |
192 | t.dst.protonum = IPPROTO_GRE; | |
1afc5679 PNA |
193 | t.src.u.gre.key = ct_pptp_info->pac_call_id; |
194 | t.dst.u.gre.key = ct_pptp_info->pns_call_id; | |
5d0aa2cc | 195 | if (!destroy_sibling_or_exp(net, ct, &t)) |
0d53778e | 196 | pr_debug("failed to timeout reply pac->pns ct/exp\n"); |
f09943fe PM |
197 | } |
198 | ||
199 | /* expect GRE connections (PNS->PAC and PAC->PNS direction) */ | |
200 | static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid) | |
201 | { | |
202 | struct nf_conntrack_expect *exp_orig, *exp_reply; | |
203 | enum ip_conntrack_dir dir; | |
204 | int ret = 1; | |
205 | typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre; | |
206 | ||
6823645d | 207 | exp_orig = nf_ct_expect_alloc(ct); |
f09943fe PM |
208 | if (exp_orig == NULL) |
209 | goto out; | |
210 | ||
6823645d | 211 | exp_reply = nf_ct_expect_alloc(ct); |
f09943fe PM |
212 | if (exp_reply == NULL) |
213 | goto out_put_orig; | |
214 | ||
215 | /* original direction, PNS->PAC */ | |
216 | dir = IP_CT_DIR_ORIGINAL; | |
6002f266 | 217 | nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT, |
5e8fbe2a | 218 | nf_ct_l3num(ct), |
6823645d PM |
219 | &ct->tuplehash[dir].tuple.src.u3, |
220 | &ct->tuplehash[dir].tuple.dst.u3, | |
221 | IPPROTO_GRE, &peer_callid, &callid); | |
f09943fe PM |
222 | exp_orig->expectfn = pptp_expectfn; |
223 | ||
224 | /* reply direction, PAC->PNS */ | |
225 | dir = IP_CT_DIR_REPLY; | |
6002f266 | 226 | nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT, |
5e8fbe2a | 227 | nf_ct_l3num(ct), |
6823645d PM |
228 | &ct->tuplehash[dir].tuple.src.u3, |
229 | &ct->tuplehash[dir].tuple.dst.u3, | |
230 | IPPROTO_GRE, &callid, &peer_callid); | |
f09943fe PM |
231 | exp_reply->expectfn = pptp_expectfn; |
232 | ||
233 | nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre); | |
234 | if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK) | |
235 | nf_nat_pptp_exp_gre(exp_orig, exp_reply); | |
6823645d | 236 | if (nf_ct_expect_related(exp_orig) != 0) |
f09943fe | 237 | goto out_put_both; |
6823645d | 238 | if (nf_ct_expect_related(exp_reply) != 0) |
f09943fe PM |
239 | goto out_unexpect_orig; |
240 | ||
241 | /* Add GRE keymap entries */ | |
242 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0) | |
243 | goto out_unexpect_both; | |
244 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) { | |
245 | nf_ct_gre_keymap_destroy(ct); | |
246 | goto out_unexpect_both; | |
247 | } | |
248 | ret = 0; | |
249 | ||
250 | out_put_both: | |
6823645d | 251 | nf_ct_expect_put(exp_reply); |
f09943fe | 252 | out_put_orig: |
6823645d | 253 | nf_ct_expect_put(exp_orig); |
f09943fe PM |
254 | out: |
255 | return ret; | |
256 | ||
257 | out_unexpect_both: | |
6823645d | 258 | nf_ct_unexpect_related(exp_reply); |
f09943fe | 259 | out_unexpect_orig: |
6823645d | 260 | nf_ct_unexpect_related(exp_orig); |
f09943fe PM |
261 | goto out_put_both; |
262 | } | |
263 | ||
2fe7c321 | 264 | static int |
051966c0 | 265 | pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
266 | struct PptpControlHeader *ctlh, |
267 | union pptp_ctrl_union *pptpReq, | |
268 | unsigned int reqlen, | |
269 | struct nf_conn *ct, | |
270 | enum ip_conntrack_info ctinfo) | |
271 | { | |
1afc5679 | 272 | struct nf_ct_pptp_master *info = nfct_help_data(ct); |
f09943fe PM |
273 | u_int16_t msg; |
274 | __be16 cid = 0, pcid = 0; | |
275 | typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound; | |
276 | ||
277 | msg = ntohs(ctlh->messageType); | |
0d53778e | 278 | pr_debug("inbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
279 | |
280 | switch (msg) { | |
281 | case PPTP_START_SESSION_REPLY: | |
282 | /* server confirms new control session */ | |
283 | if (info->sstate < PPTP_SESSION_REQUESTED) | |
284 | goto invalid; | |
285 | if (pptpReq->srep.resultCode == PPTP_START_OK) | |
286 | info->sstate = PPTP_SESSION_CONFIRMED; | |
287 | else | |
288 | info->sstate = PPTP_SESSION_ERROR; | |
289 | break; | |
290 | ||
291 | case PPTP_STOP_SESSION_REPLY: | |
292 | /* server confirms end of control session */ | |
293 | if (info->sstate > PPTP_SESSION_STOPREQ) | |
294 | goto invalid; | |
295 | if (pptpReq->strep.resultCode == PPTP_STOP_OK) | |
296 | info->sstate = PPTP_SESSION_NONE; | |
297 | else | |
298 | info->sstate = PPTP_SESSION_ERROR; | |
299 | break; | |
300 | ||
301 | case PPTP_OUT_CALL_REPLY: | |
302 | /* server accepted call, we now expect GRE frames */ | |
303 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
304 | goto invalid; | |
305 | if (info->cstate != PPTP_CALL_OUT_REQ && | |
306 | info->cstate != PPTP_CALL_OUT_CONF) | |
307 | goto invalid; | |
308 | ||
309 | cid = pptpReq->ocack.callID; | |
310 | pcid = pptpReq->ocack.peersCallID; | |
311 | if (info->pns_call_id != pcid) | |
312 | goto invalid; | |
0d53778e PM |
313 | pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], |
314 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
315 | |
316 | if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) { | |
317 | info->cstate = PPTP_CALL_OUT_CONF; | |
318 | info->pac_call_id = cid; | |
319 | exp_gre(ct, cid, pcid); | |
320 | } else | |
321 | info->cstate = PPTP_CALL_NONE; | |
322 | break; | |
323 | ||
324 | case PPTP_IN_CALL_REQUEST: | |
325 | /* server tells us about incoming call request */ | |
326 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
327 | goto invalid; | |
328 | ||
329 | cid = pptpReq->icreq.callID; | |
0d53778e | 330 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
331 | info->cstate = PPTP_CALL_IN_REQ; |
332 | info->pac_call_id = cid; | |
333 | break; | |
334 | ||
335 | case PPTP_IN_CALL_CONNECT: | |
336 | /* server tells us about incoming call established */ | |
337 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
338 | goto invalid; | |
339 | if (info->cstate != PPTP_CALL_IN_REP && | |
340 | info->cstate != PPTP_CALL_IN_CONF) | |
341 | goto invalid; | |
342 | ||
343 | pcid = pptpReq->iccon.peersCallID; | |
344 | cid = info->pac_call_id; | |
345 | ||
346 | if (info->pns_call_id != pcid) | |
347 | goto invalid; | |
348 | ||
0d53778e | 349 | pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid)); |
f09943fe PM |
350 | info->cstate = PPTP_CALL_IN_CONF; |
351 | ||
352 | /* we expect a GRE connection from PAC to PNS */ | |
353 | exp_gre(ct, cid, pcid); | |
354 | break; | |
355 | ||
356 | case PPTP_CALL_DISCONNECT_NOTIFY: | |
357 | /* server confirms disconnect */ | |
358 | cid = pptpReq->disc.callID; | |
0d53778e | 359 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
360 | info->cstate = PPTP_CALL_NONE; |
361 | ||
362 | /* untrack this call id, unexpect GRE packets */ | |
363 | pptp_destroy_siblings(ct); | |
364 | break; | |
365 | ||
366 | case PPTP_WAN_ERROR_NOTIFY: | |
4c6e4209 | 367 | case PPTP_SET_LINK_INFO: |
f09943fe PM |
368 | case PPTP_ECHO_REQUEST: |
369 | case PPTP_ECHO_REPLY: | |
370 | /* I don't have to explain these ;) */ | |
371 | break; | |
372 | ||
373 | default: | |
374 | goto invalid; | |
375 | } | |
376 | ||
377 | nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound); | |
378 | if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK) | |
051966c0 PM |
379 | return nf_nat_pptp_inbound(skb, ct, ctinfo, |
380 | protoff, ctlh, pptpReq); | |
f09943fe PM |
381 | return NF_ACCEPT; |
382 | ||
383 | invalid: | |
0d53778e PM |
384 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
385 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
386 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
387 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
388 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
389 | return NF_ACCEPT; |
390 | } | |
391 | ||
2fe7c321 | 392 | static int |
051966c0 | 393 | pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
394 | struct PptpControlHeader *ctlh, |
395 | union pptp_ctrl_union *pptpReq, | |
396 | unsigned int reqlen, | |
397 | struct nf_conn *ct, | |
398 | enum ip_conntrack_info ctinfo) | |
399 | { | |
1afc5679 | 400 | struct nf_ct_pptp_master *info = nfct_help_data(ct); |
f09943fe PM |
401 | u_int16_t msg; |
402 | __be16 cid = 0, pcid = 0; | |
403 | typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound; | |
404 | ||
405 | msg = ntohs(ctlh->messageType); | |
0d53778e | 406 | pr_debug("outbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
407 | |
408 | switch (msg) { | |
409 | case PPTP_START_SESSION_REQUEST: | |
410 | /* client requests for new control session */ | |
411 | if (info->sstate != PPTP_SESSION_NONE) | |
412 | goto invalid; | |
413 | info->sstate = PPTP_SESSION_REQUESTED; | |
414 | break; | |
415 | ||
416 | case PPTP_STOP_SESSION_REQUEST: | |
417 | /* client requests end of control session */ | |
418 | info->sstate = PPTP_SESSION_STOPREQ; | |
419 | break; | |
420 | ||
421 | case PPTP_OUT_CALL_REQUEST: | |
422 | /* client initiating connection to server */ | |
423 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
424 | goto invalid; | |
425 | info->cstate = PPTP_CALL_OUT_REQ; | |
426 | /* track PNS call id */ | |
427 | cid = pptpReq->ocreq.callID; | |
0d53778e | 428 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
429 | info->pns_call_id = cid; |
430 | break; | |
431 | ||
432 | case PPTP_IN_CALL_REPLY: | |
433 | /* client answers incoming call */ | |
434 | if (info->cstate != PPTP_CALL_IN_REQ && | |
435 | info->cstate != PPTP_CALL_IN_REP) | |
436 | goto invalid; | |
437 | ||
438 | cid = pptpReq->icack.callID; | |
439 | pcid = pptpReq->icack.peersCallID; | |
440 | if (info->pac_call_id != pcid) | |
441 | goto invalid; | |
0d53778e PM |
442 | pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg], |
443 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
444 | |
445 | if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) { | |
446 | /* part two of the three-way handshake */ | |
447 | info->cstate = PPTP_CALL_IN_REP; | |
448 | info->pns_call_id = cid; | |
449 | } else | |
450 | info->cstate = PPTP_CALL_NONE; | |
451 | break; | |
452 | ||
453 | case PPTP_CALL_CLEAR_REQUEST: | |
454 | /* client requests hangup of call */ | |
455 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
456 | goto invalid; | |
457 | /* FUTURE: iterate over all calls and check if | |
458 | * call ID is valid. We don't do this without newnat, | |
459 | * because we only know about last call */ | |
460 | info->cstate = PPTP_CALL_CLEAR_REQ; | |
461 | break; | |
462 | ||
463 | case PPTP_SET_LINK_INFO: | |
464 | case PPTP_ECHO_REQUEST: | |
465 | case PPTP_ECHO_REPLY: | |
466 | /* I don't have to explain these ;) */ | |
467 | break; | |
468 | ||
469 | default: | |
470 | goto invalid; | |
471 | } | |
472 | ||
473 | nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound); | |
474 | if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK) | |
051966c0 PM |
475 | return nf_nat_pptp_outbound(skb, ct, ctinfo, |
476 | protoff, ctlh, pptpReq); | |
f09943fe PM |
477 | return NF_ACCEPT; |
478 | ||
479 | invalid: | |
0d53778e PM |
480 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
481 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
482 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
483 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
484 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
485 | return NF_ACCEPT; |
486 | } | |
487 | ||
488 | static const unsigned int pptp_msg_size[] = { | |
489 | [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest), | |
490 | [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply), | |
491 | [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest), | |
492 | [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply), | |
493 | [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest), | |
494 | [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply), | |
495 | [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest), | |
496 | [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply), | |
497 | [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected), | |
498 | [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest), | |
499 | [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify), | |
500 | [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify), | |
501 | [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo), | |
502 | }; | |
503 | ||
504 | /* track caller id inside control connection, call expect_related */ | |
505 | static int | |
3db05fea | 506 | conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
507 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
508 | ||
509 | { | |
510 | int dir = CTINFO2DIR(ctinfo); | |
1afc5679 | 511 | const struct nf_ct_pptp_master *info = nfct_help_data(ct); |
9ddd0ed0 JE |
512 | const struct tcphdr *tcph; |
513 | struct tcphdr _tcph; | |
514 | const struct pptp_pkt_hdr *pptph; | |
515 | struct pptp_pkt_hdr _pptph; | |
f09943fe PM |
516 | struct PptpControlHeader _ctlh, *ctlh; |
517 | union pptp_ctrl_union _pptpReq, *pptpReq; | |
3db05fea | 518 | unsigned int tcplen = skb->len - protoff; |
f09943fe PM |
519 | unsigned int datalen, reqlen, nexthdr_off; |
520 | int oldsstate, oldcstate; | |
521 | int ret; | |
522 | u_int16_t msg; | |
523 | ||
2fe7c321 FW |
524 | #if IS_ENABLED(CONFIG_NF_NAT) |
525 | if (!nf_ct_is_confirmed(ct) && (ct->status & IPS_NAT_MASK)) { | |
526 | struct nf_conn_nat *nat = nf_ct_ext_find(ct, NF_CT_EXT_NAT); | |
527 | ||
528 | if (!nat && !nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC)) | |
529 | return NF_DROP; | |
530 | } | |
531 | #endif | |
f09943fe | 532 | /* don't do any tracking before tcp handshake complete */ |
fb048833 | 533 | if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY) |
f09943fe PM |
534 | return NF_ACCEPT; |
535 | ||
536 | nexthdr_off = protoff; | |
3db05fea | 537 | tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph); |
f09943fe PM |
538 | BUG_ON(!tcph); |
539 | nexthdr_off += tcph->doff * 4; | |
601e68e1 | 540 | datalen = tcplen - tcph->doff * 4; |
f09943fe | 541 | |
3db05fea | 542 | pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph); |
f09943fe | 543 | if (!pptph) { |
0d53778e | 544 | pr_debug("no full PPTP header, can't track\n"); |
f09943fe PM |
545 | return NF_ACCEPT; |
546 | } | |
547 | nexthdr_off += sizeof(_pptph); | |
548 | datalen -= sizeof(_pptph); | |
549 | ||
550 | /* if it's not a control message we can't do anything with it */ | |
551 | if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL || | |
552 | ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) { | |
0d53778e | 553 | pr_debug("not a control packet\n"); |
f09943fe PM |
554 | return NF_ACCEPT; |
555 | } | |
556 | ||
3db05fea | 557 | ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh); |
f09943fe PM |
558 | if (!ctlh) |
559 | return NF_ACCEPT; | |
560 | nexthdr_off += sizeof(_ctlh); | |
561 | datalen -= sizeof(_ctlh); | |
562 | ||
563 | reqlen = datalen; | |
564 | msg = ntohs(ctlh->messageType); | |
565 | if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg]) | |
566 | return NF_ACCEPT; | |
567 | if (reqlen > sizeof(*pptpReq)) | |
568 | reqlen = sizeof(*pptpReq); | |
569 | ||
3db05fea | 570 | pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq); |
f09943fe PM |
571 | if (!pptpReq) |
572 | return NF_ACCEPT; | |
573 | ||
574 | oldsstate = info->sstate; | |
575 | oldcstate = info->cstate; | |
576 | ||
577 | spin_lock_bh(&nf_pptp_lock); | |
578 | ||
579 | /* FIXME: We just blindly assume that the control connection is always | |
580 | * established from PNS->PAC. However, RFC makes no guarantee */ | |
581 | if (dir == IP_CT_DIR_ORIGINAL) | |
582 | /* client -> server (PNS -> PAC) */ | |
051966c0 | 583 | ret = pptp_outbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct, |
f09943fe PM |
584 | ctinfo); |
585 | else | |
586 | /* server -> client (PAC -> PNS) */ | |
051966c0 | 587 | ret = pptp_inbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct, |
f09943fe | 588 | ctinfo); |
0d53778e PM |
589 | pr_debug("sstate: %d->%d, cstate: %d->%d\n", |
590 | oldsstate, info->sstate, oldcstate, info->cstate); | |
f09943fe PM |
591 | spin_unlock_bh(&nf_pptp_lock); |
592 | ||
593 | return ret; | |
594 | } | |
595 | ||
6002f266 PM |
596 | static const struct nf_conntrack_expect_policy pptp_exp_policy = { |
597 | .max_expected = 2, | |
598 | .timeout = 5 * 60, | |
599 | }; | |
600 | ||
f09943fe PM |
601 | /* control protocol helper */ |
602 | static struct nf_conntrack_helper pptp __read_mostly = { | |
603 | .name = "pptp", | |
604 | .me = THIS_MODULE, | |
f09943fe | 605 | .tuple.src.l3num = AF_INET, |
09640e63 | 606 | .tuple.src.u.tcp.port = cpu_to_be16(PPTP_CONTROL_PORT), |
f09943fe | 607 | .tuple.dst.protonum = IPPROTO_TCP, |
f09943fe PM |
608 | .help = conntrack_pptp_help, |
609 | .destroy = pptp_destroy_siblings, | |
6002f266 | 610 | .expect_policy = &pptp_exp_policy, |
f09943fe PM |
611 | }; |
612 | ||
613 | static int __init nf_conntrack_pptp_init(void) | |
614 | { | |
dcf67740 FW |
615 | NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_pptp_master)); |
616 | ||
8142b227 | 617 | return nf_conntrack_helper_register(&pptp); |
f09943fe PM |
618 | } |
619 | ||
620 | static void __exit nf_conntrack_pptp_fini(void) | |
621 | { | |
622 | nf_conntrack_helper_unregister(&pptp); | |
f09943fe PM |
623 | } |
624 | ||
625 | module_init(nf_conntrack_pptp_init); | |
626 | module_exit(nf_conntrack_pptp_fini); |