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09c434b8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
f09943fe PM |
2 | /* |
3 | * Connection tracking support for PPTP (Point to Point Tunneling Protocol). | |
4 | * PPTP is a a protocol for creating virtual private networks. | |
5 | * It is a specification defined by Microsoft and some vendors | |
6 | * working with Microsoft. PPTP is built on top of a modified | |
7 | * version of the Internet Generic Routing Encapsulation Protocol. | |
8 | * GRE is defined in RFC 1701 and RFC 1702. Documentation of | |
9 | * PPTP can be found in RFC 2637 | |
10 | * | |
11 | * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org> | |
12 | * | |
13 | * Development of this code funded by Astaro AG (http://www.astaro.com/) | |
14 | * | |
f229f6ce PM |
15 | * (C) 2006-2012 Patrick McHardy <kaber@trash.net> |
16 | * | |
f09943fe PM |
17 | * Limitations: |
18 | * - We blindly assume that control connections are always | |
19 | * established in PNS->PAC direction. This is a violation | |
38124328 | 20 | * of RFC 2637 |
f09943fe PM |
21 | * - We can only support one single call within each session |
22 | * TODO: | |
23 | * - testing of incoming PPTP calls | |
24 | */ | |
25 | ||
26 | #include <linux/module.h> | |
27 | #include <linux/skbuff.h> | |
28 | #include <linux/in.h> | |
29 | #include <linux/tcp.h> | |
30 | ||
31 | #include <net/netfilter/nf_conntrack.h> | |
32 | #include <net/netfilter/nf_conntrack_core.h> | |
33 | #include <net/netfilter/nf_conntrack_helper.h> | |
5d0aa2cc | 34 | #include <net/netfilter/nf_conntrack_zones.h> |
f09943fe PM |
35 | #include <linux/netfilter/nf_conntrack_proto_gre.h> |
36 | #include <linux/netfilter/nf_conntrack_pptp.h> | |
37 | ||
38 | #define NF_CT_PPTP_VERSION "3.1" | |
39 | ||
40 | MODULE_LICENSE("GPL"); | |
41 | MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); | |
42 | MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP"); | |
43 | MODULE_ALIAS("ip_conntrack_pptp"); | |
4dc06f96 | 44 | MODULE_ALIAS_NFCT_HELPER("pptp"); |
f09943fe PM |
45 | |
46 | static DEFINE_SPINLOCK(nf_pptp_lock); | |
47 | ||
48 | int | |
3db05fea | 49 | (*nf_nat_pptp_hook_outbound)(struct sk_buff *skb, |
f09943fe | 50 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
051966c0 | 51 | unsigned int protoff, struct PptpControlHeader *ctlh, |
f09943fe PM |
52 | union pptp_ctrl_union *pptpReq) __read_mostly; |
53 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_outbound); | |
54 | ||
55 | int | |
3db05fea | 56 | (*nf_nat_pptp_hook_inbound)(struct sk_buff *skb, |
f09943fe | 57 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
051966c0 | 58 | unsigned int protoff, struct PptpControlHeader *ctlh, |
f09943fe PM |
59 | union pptp_ctrl_union *pptpReq) __read_mostly; |
60 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_inbound); | |
61 | ||
62 | void | |
63 | (*nf_nat_pptp_hook_exp_gre)(struct nf_conntrack_expect *expect_orig, | |
64 | struct nf_conntrack_expect *expect_reply) | |
65 | __read_mostly; | |
66 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_exp_gre); | |
67 | ||
68 | void | |
69 | (*nf_nat_pptp_hook_expectfn)(struct nf_conn *ct, | |
70 | struct nf_conntrack_expect *exp) __read_mostly; | |
71 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn); | |
72 | ||
e9d376f0 | 73 | #if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG) |
f09943fe | 74 | /* PptpControlMessageType names */ |
9ddd0ed0 | 75 | const char *const pptp_msg_name[] = { |
f09943fe PM |
76 | "UNKNOWN_MESSAGE", |
77 | "START_SESSION_REQUEST", | |
78 | "START_SESSION_REPLY", | |
79 | "STOP_SESSION_REQUEST", | |
80 | "STOP_SESSION_REPLY", | |
81 | "ECHO_REQUEST", | |
82 | "ECHO_REPLY", | |
83 | "OUT_CALL_REQUEST", | |
84 | "OUT_CALL_REPLY", | |
85 | "IN_CALL_REQUEST", | |
86 | "IN_CALL_REPLY", | |
87 | "IN_CALL_CONNECT", | |
88 | "CALL_CLEAR_REQUEST", | |
89 | "CALL_DISCONNECT_NOTIFY", | |
90 | "WAN_ERROR_NOTIFY", | |
91 | "SET_LINK_INFO" | |
92 | }; | |
93 | EXPORT_SYMBOL(pptp_msg_name); | |
f09943fe PM |
94 | #endif |
95 | ||
96 | #define SECS *HZ | |
97 | #define MINS * 60 SECS | |
98 | #define HOURS * 60 MINS | |
99 | ||
100 | #define PPTP_GRE_TIMEOUT (10 MINS) | |
101 | #define PPTP_GRE_STREAM_TIMEOUT (5 HOURS) | |
102 | ||
103 | static void pptp_expectfn(struct nf_conn *ct, | |
104 | struct nf_conntrack_expect *exp) | |
105 | { | |
0e6e75af | 106 | struct net *net = nf_ct_net(ct); |
f09943fe | 107 | typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn; |
0d53778e | 108 | pr_debug("increasing timeouts\n"); |
f09943fe PM |
109 | |
110 | /* increase timeout of GRE data channel conntrack entry */ | |
111 | ct->proto.gre.timeout = PPTP_GRE_TIMEOUT; | |
112 | ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT; | |
113 | ||
114 | /* Can you see how rusty this code is, compared with the pre-2.6.11 | |
115 | * one? That's what happened to my shiny newnat of 2002 ;( -HW */ | |
116 | ||
f09943fe | 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 */ | |
303e0c55 | 125 | nf_ct_invert_tuple(&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 | } | |
f09943fe PM |
139 | } |
140 | ||
5d0aa2cc | 141 | static int destroy_sibling_or_exp(struct net *net, struct nf_conn *ct, |
0e6e75af | 142 | const struct nf_conntrack_tuple *t) |
f09943fe | 143 | { |
9ddd0ed0 | 144 | const struct nf_conntrack_tuple_hash *h; |
308ac914 | 145 | const struct nf_conntrack_zone *zone; |
f09943fe PM |
146 | struct nf_conntrack_expect *exp; |
147 | struct nf_conn *sibling; | |
148 | ||
0d53778e | 149 | pr_debug("trying to timeout ct or exp for tuple "); |
3c9fba65 | 150 | nf_ct_dump_tuple(t); |
f09943fe | 151 | |
308ac914 | 152 | zone = nf_ct_zone(ct); |
5d0aa2cc | 153 | h = nf_conntrack_find_get(net, zone, t); |
f09943fe PM |
154 | if (h) { |
155 | sibling = nf_ct_tuplehash_to_ctrack(h); | |
0d53778e | 156 | pr_debug("setting timeout of conntrack %p to 0\n", sibling); |
f09943fe PM |
157 | sibling->proto.gre.timeout = 0; |
158 | sibling->proto.gre.stream_timeout = 0; | |
f330a7fd | 159 | nf_ct_kill(sibling); |
f09943fe PM |
160 | nf_ct_put(sibling); |
161 | return 1; | |
162 | } else { | |
5d0aa2cc | 163 | exp = nf_ct_expect_find_get(net, zone, t); |
f09943fe | 164 | if (exp) { |
0d53778e | 165 | pr_debug("unexpect_related of expect %p\n", exp); |
6823645d PM |
166 | nf_ct_unexpect_related(exp); |
167 | nf_ct_expect_put(exp); | |
f09943fe PM |
168 | return 1; |
169 | } | |
170 | } | |
171 | return 0; | |
172 | } | |
173 | ||
174 | /* timeout GRE data connections */ | |
175 | static void pptp_destroy_siblings(struct nf_conn *ct) | |
176 | { | |
0e6e75af | 177 | struct net *net = nf_ct_net(ct); |
1afc5679 | 178 | const struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct); |
f09943fe PM |
179 | struct nf_conntrack_tuple t; |
180 | ||
181 | nf_ct_gre_keymap_destroy(ct); | |
182 | ||
183 | /* try original (pns->pac) tuple */ | |
184 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t)); | |
185 | t.dst.protonum = IPPROTO_GRE; | |
1afc5679 PNA |
186 | t.src.u.gre.key = ct_pptp_info->pns_call_id; |
187 | t.dst.u.gre.key = ct_pptp_info->pac_call_id; | |
5d0aa2cc | 188 | if (!destroy_sibling_or_exp(net, ct, &t)) |
0d53778e | 189 | pr_debug("failed to timeout original pns->pac ct/exp\n"); |
f09943fe PM |
190 | |
191 | /* try reply (pac->pns) tuple */ | |
192 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t)); | |
193 | t.dst.protonum = IPPROTO_GRE; | |
1afc5679 PNA |
194 | t.src.u.gre.key = ct_pptp_info->pac_call_id; |
195 | t.dst.u.gre.key = ct_pptp_info->pns_call_id; | |
5d0aa2cc | 196 | if (!destroy_sibling_or_exp(net, ct, &t)) |
0d53778e | 197 | pr_debug("failed to timeout reply pac->pns ct/exp\n"); |
f09943fe PM |
198 | } |
199 | ||
200 | /* expect GRE connections (PNS->PAC and PAC->PNS direction) */ | |
201 | static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid) | |
202 | { | |
203 | struct nf_conntrack_expect *exp_orig, *exp_reply; | |
204 | enum ip_conntrack_dir dir; | |
205 | int ret = 1; | |
206 | typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre; | |
207 | ||
6823645d | 208 | exp_orig = nf_ct_expect_alloc(ct); |
f09943fe PM |
209 | if (exp_orig == NULL) |
210 | goto out; | |
211 | ||
6823645d | 212 | exp_reply = nf_ct_expect_alloc(ct); |
f09943fe PM |
213 | if (exp_reply == NULL) |
214 | goto out_put_orig; | |
215 | ||
216 | /* original direction, PNS->PAC */ | |
217 | dir = IP_CT_DIR_ORIGINAL; | |
6002f266 | 218 | nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT, |
5e8fbe2a | 219 | nf_ct_l3num(ct), |
6823645d PM |
220 | &ct->tuplehash[dir].tuple.src.u3, |
221 | &ct->tuplehash[dir].tuple.dst.u3, | |
222 | IPPROTO_GRE, &peer_callid, &callid); | |
f09943fe PM |
223 | exp_orig->expectfn = pptp_expectfn; |
224 | ||
225 | /* reply direction, PAC->PNS */ | |
226 | dir = IP_CT_DIR_REPLY; | |
6002f266 | 227 | nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT, |
5e8fbe2a | 228 | nf_ct_l3num(ct), |
6823645d PM |
229 | &ct->tuplehash[dir].tuple.src.u3, |
230 | &ct->tuplehash[dir].tuple.dst.u3, | |
231 | IPPROTO_GRE, &callid, &peer_callid); | |
f09943fe PM |
232 | exp_reply->expectfn = pptp_expectfn; |
233 | ||
234 | nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre); | |
235 | if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK) | |
236 | nf_nat_pptp_exp_gre(exp_orig, exp_reply); | |
6823645d | 237 | if (nf_ct_expect_related(exp_orig) != 0) |
f09943fe | 238 | goto out_put_both; |
6823645d | 239 | if (nf_ct_expect_related(exp_reply) != 0) |
f09943fe PM |
240 | goto out_unexpect_orig; |
241 | ||
242 | /* Add GRE keymap entries */ | |
243 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0) | |
244 | goto out_unexpect_both; | |
245 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) { | |
246 | nf_ct_gre_keymap_destroy(ct); | |
247 | goto out_unexpect_both; | |
248 | } | |
249 | ret = 0; | |
250 | ||
251 | out_put_both: | |
6823645d | 252 | nf_ct_expect_put(exp_reply); |
f09943fe | 253 | out_put_orig: |
6823645d | 254 | nf_ct_expect_put(exp_orig); |
f09943fe PM |
255 | out: |
256 | return ret; | |
257 | ||
258 | out_unexpect_both: | |
6823645d | 259 | nf_ct_unexpect_related(exp_reply); |
f09943fe | 260 | out_unexpect_orig: |
6823645d | 261 | nf_ct_unexpect_related(exp_orig); |
f09943fe PM |
262 | goto out_put_both; |
263 | } | |
264 | ||
2fe7c321 | 265 | static int |
051966c0 | 266 | pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
267 | struct PptpControlHeader *ctlh, |
268 | union pptp_ctrl_union *pptpReq, | |
269 | unsigned int reqlen, | |
270 | struct nf_conn *ct, | |
271 | enum ip_conntrack_info ctinfo) | |
272 | { | |
1afc5679 | 273 | struct nf_ct_pptp_master *info = nfct_help_data(ct); |
f09943fe PM |
274 | u_int16_t msg; |
275 | __be16 cid = 0, pcid = 0; | |
276 | typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound; | |
277 | ||
278 | msg = ntohs(ctlh->messageType); | |
0d53778e | 279 | pr_debug("inbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
280 | |
281 | switch (msg) { | |
282 | case PPTP_START_SESSION_REPLY: | |
283 | /* server confirms new control session */ | |
284 | if (info->sstate < PPTP_SESSION_REQUESTED) | |
285 | goto invalid; | |
286 | if (pptpReq->srep.resultCode == PPTP_START_OK) | |
287 | info->sstate = PPTP_SESSION_CONFIRMED; | |
288 | else | |
289 | info->sstate = PPTP_SESSION_ERROR; | |
290 | break; | |
291 | ||
292 | case PPTP_STOP_SESSION_REPLY: | |
293 | /* server confirms end of control session */ | |
294 | if (info->sstate > PPTP_SESSION_STOPREQ) | |
295 | goto invalid; | |
296 | if (pptpReq->strep.resultCode == PPTP_STOP_OK) | |
297 | info->sstate = PPTP_SESSION_NONE; | |
298 | else | |
299 | info->sstate = PPTP_SESSION_ERROR; | |
300 | break; | |
301 | ||
302 | case PPTP_OUT_CALL_REPLY: | |
303 | /* server accepted call, we now expect GRE frames */ | |
304 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
305 | goto invalid; | |
306 | if (info->cstate != PPTP_CALL_OUT_REQ && | |
307 | info->cstate != PPTP_CALL_OUT_CONF) | |
308 | goto invalid; | |
309 | ||
310 | cid = pptpReq->ocack.callID; | |
311 | pcid = pptpReq->ocack.peersCallID; | |
312 | if (info->pns_call_id != pcid) | |
313 | goto invalid; | |
0d53778e PM |
314 | pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], |
315 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
316 | |
317 | if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) { | |
318 | info->cstate = PPTP_CALL_OUT_CONF; | |
319 | info->pac_call_id = cid; | |
320 | exp_gre(ct, cid, pcid); | |
321 | } else | |
322 | info->cstate = PPTP_CALL_NONE; | |
323 | break; | |
324 | ||
325 | case PPTP_IN_CALL_REQUEST: | |
326 | /* server tells us about incoming call request */ | |
327 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
328 | goto invalid; | |
329 | ||
330 | cid = pptpReq->icreq.callID; | |
0d53778e | 331 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
332 | info->cstate = PPTP_CALL_IN_REQ; |
333 | info->pac_call_id = cid; | |
334 | break; | |
335 | ||
336 | case PPTP_IN_CALL_CONNECT: | |
337 | /* server tells us about incoming call established */ | |
338 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
339 | goto invalid; | |
340 | if (info->cstate != PPTP_CALL_IN_REP && | |
341 | info->cstate != PPTP_CALL_IN_CONF) | |
342 | goto invalid; | |
343 | ||
344 | pcid = pptpReq->iccon.peersCallID; | |
345 | cid = info->pac_call_id; | |
346 | ||
347 | if (info->pns_call_id != pcid) | |
348 | goto invalid; | |
349 | ||
0d53778e | 350 | pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid)); |
f09943fe PM |
351 | info->cstate = PPTP_CALL_IN_CONF; |
352 | ||
353 | /* we expect a GRE connection from PAC to PNS */ | |
354 | exp_gre(ct, cid, pcid); | |
355 | break; | |
356 | ||
357 | case PPTP_CALL_DISCONNECT_NOTIFY: | |
358 | /* server confirms disconnect */ | |
359 | cid = pptpReq->disc.callID; | |
0d53778e | 360 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
361 | info->cstate = PPTP_CALL_NONE; |
362 | ||
363 | /* untrack this call id, unexpect GRE packets */ | |
364 | pptp_destroy_siblings(ct); | |
365 | break; | |
366 | ||
367 | case PPTP_WAN_ERROR_NOTIFY: | |
4c6e4209 | 368 | case PPTP_SET_LINK_INFO: |
f09943fe PM |
369 | case PPTP_ECHO_REQUEST: |
370 | case PPTP_ECHO_REPLY: | |
371 | /* I don't have to explain these ;) */ | |
372 | break; | |
373 | ||
374 | default: | |
375 | goto invalid; | |
376 | } | |
377 | ||
378 | nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound); | |
379 | if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK) | |
051966c0 PM |
380 | return nf_nat_pptp_inbound(skb, ct, ctinfo, |
381 | protoff, ctlh, pptpReq); | |
f09943fe PM |
382 | return NF_ACCEPT; |
383 | ||
384 | invalid: | |
0d53778e PM |
385 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
386 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
387 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
388 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
389 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
390 | return NF_ACCEPT; |
391 | } | |
392 | ||
2fe7c321 | 393 | static int |
051966c0 | 394 | pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
395 | struct PptpControlHeader *ctlh, |
396 | union pptp_ctrl_union *pptpReq, | |
397 | unsigned int reqlen, | |
398 | struct nf_conn *ct, | |
399 | enum ip_conntrack_info ctinfo) | |
400 | { | |
1afc5679 | 401 | struct nf_ct_pptp_master *info = nfct_help_data(ct); |
f09943fe PM |
402 | u_int16_t msg; |
403 | __be16 cid = 0, pcid = 0; | |
404 | typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound; | |
405 | ||
406 | msg = ntohs(ctlh->messageType); | |
0d53778e | 407 | pr_debug("outbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
408 | |
409 | switch (msg) { | |
410 | case PPTP_START_SESSION_REQUEST: | |
411 | /* client requests for new control session */ | |
412 | if (info->sstate != PPTP_SESSION_NONE) | |
413 | goto invalid; | |
414 | info->sstate = PPTP_SESSION_REQUESTED; | |
415 | break; | |
416 | ||
417 | case PPTP_STOP_SESSION_REQUEST: | |
418 | /* client requests end of control session */ | |
419 | info->sstate = PPTP_SESSION_STOPREQ; | |
420 | break; | |
421 | ||
422 | case PPTP_OUT_CALL_REQUEST: | |
423 | /* client initiating connection to server */ | |
424 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
425 | goto invalid; | |
426 | info->cstate = PPTP_CALL_OUT_REQ; | |
427 | /* track PNS call id */ | |
428 | cid = pptpReq->ocreq.callID; | |
0d53778e | 429 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
430 | info->pns_call_id = cid; |
431 | break; | |
432 | ||
433 | case PPTP_IN_CALL_REPLY: | |
434 | /* client answers incoming call */ | |
435 | if (info->cstate != PPTP_CALL_IN_REQ && | |
436 | info->cstate != PPTP_CALL_IN_REP) | |
437 | goto invalid; | |
438 | ||
439 | cid = pptpReq->icack.callID; | |
440 | pcid = pptpReq->icack.peersCallID; | |
441 | if (info->pac_call_id != pcid) | |
442 | goto invalid; | |
0d53778e PM |
443 | pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg], |
444 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
445 | |
446 | if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) { | |
447 | /* part two of the three-way handshake */ | |
448 | info->cstate = PPTP_CALL_IN_REP; | |
449 | info->pns_call_id = cid; | |
450 | } else | |
451 | info->cstate = PPTP_CALL_NONE; | |
452 | break; | |
453 | ||
454 | case PPTP_CALL_CLEAR_REQUEST: | |
455 | /* client requests hangup of call */ | |
456 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
457 | goto invalid; | |
458 | /* FUTURE: iterate over all calls and check if | |
459 | * call ID is valid. We don't do this without newnat, | |
460 | * because we only know about last call */ | |
461 | info->cstate = PPTP_CALL_CLEAR_REQ; | |
462 | break; | |
463 | ||
464 | case PPTP_SET_LINK_INFO: | |
465 | case PPTP_ECHO_REQUEST: | |
466 | case PPTP_ECHO_REPLY: | |
467 | /* I don't have to explain these ;) */ | |
468 | break; | |
469 | ||
470 | default: | |
471 | goto invalid; | |
472 | } | |
473 | ||
474 | nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound); | |
475 | if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK) | |
051966c0 PM |
476 | return nf_nat_pptp_outbound(skb, ct, ctinfo, |
477 | protoff, ctlh, pptpReq); | |
f09943fe PM |
478 | return NF_ACCEPT; |
479 | ||
480 | invalid: | |
0d53778e PM |
481 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
482 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
483 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
484 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
485 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
486 | return NF_ACCEPT; |
487 | } | |
488 | ||
489 | static const unsigned int pptp_msg_size[] = { | |
490 | [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest), | |
491 | [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply), | |
492 | [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest), | |
493 | [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply), | |
494 | [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest), | |
495 | [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply), | |
496 | [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest), | |
497 | [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply), | |
498 | [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected), | |
499 | [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest), | |
500 | [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify), | |
501 | [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify), | |
502 | [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo), | |
503 | }; | |
504 | ||
505 | /* track caller id inside control connection, call expect_related */ | |
506 | static int | |
3db05fea | 507 | conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
508 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
509 | ||
510 | { | |
511 | int dir = CTINFO2DIR(ctinfo); | |
1afc5679 | 512 | const struct nf_ct_pptp_master *info = nfct_help_data(ct); |
9ddd0ed0 JE |
513 | const struct tcphdr *tcph; |
514 | struct tcphdr _tcph; | |
515 | const struct pptp_pkt_hdr *pptph; | |
516 | struct pptp_pkt_hdr _pptph; | |
f09943fe PM |
517 | struct PptpControlHeader _ctlh, *ctlh; |
518 | union pptp_ctrl_union _pptpReq, *pptpReq; | |
3db05fea | 519 | unsigned int tcplen = skb->len - protoff; |
f09943fe PM |
520 | unsigned int datalen, reqlen, nexthdr_off; |
521 | int oldsstate, oldcstate; | |
522 | int ret; | |
523 | u_int16_t msg; | |
524 | ||
2fe7c321 FW |
525 | #if IS_ENABLED(CONFIG_NF_NAT) |
526 | if (!nf_ct_is_confirmed(ct) && (ct->status & IPS_NAT_MASK)) { | |
527 | struct nf_conn_nat *nat = nf_ct_ext_find(ct, NF_CT_EXT_NAT); | |
528 | ||
529 | if (!nat && !nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC)) | |
530 | return NF_DROP; | |
531 | } | |
532 | #endif | |
f09943fe | 533 | /* don't do any tracking before tcp handshake complete */ |
fb048833 | 534 | if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY) |
f09943fe PM |
535 | return NF_ACCEPT; |
536 | ||
537 | nexthdr_off = protoff; | |
3db05fea | 538 | tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph); |
f09943fe PM |
539 | BUG_ON(!tcph); |
540 | nexthdr_off += tcph->doff * 4; | |
601e68e1 | 541 | datalen = tcplen - tcph->doff * 4; |
f09943fe | 542 | |
3db05fea | 543 | pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph); |
f09943fe | 544 | if (!pptph) { |
0d53778e | 545 | pr_debug("no full PPTP header, can't track\n"); |
f09943fe PM |
546 | return NF_ACCEPT; |
547 | } | |
548 | nexthdr_off += sizeof(_pptph); | |
549 | datalen -= sizeof(_pptph); | |
550 | ||
551 | /* if it's not a control message we can't do anything with it */ | |
552 | if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL || | |
553 | ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) { | |
0d53778e | 554 | pr_debug("not a control packet\n"); |
f09943fe PM |
555 | return NF_ACCEPT; |
556 | } | |
557 | ||
3db05fea | 558 | ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh); |
f09943fe PM |
559 | if (!ctlh) |
560 | return NF_ACCEPT; | |
561 | nexthdr_off += sizeof(_ctlh); | |
562 | datalen -= sizeof(_ctlh); | |
563 | ||
564 | reqlen = datalen; | |
565 | msg = ntohs(ctlh->messageType); | |
566 | if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg]) | |
567 | return NF_ACCEPT; | |
568 | if (reqlen > sizeof(*pptpReq)) | |
569 | reqlen = sizeof(*pptpReq); | |
570 | ||
3db05fea | 571 | pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq); |
f09943fe PM |
572 | if (!pptpReq) |
573 | return NF_ACCEPT; | |
574 | ||
575 | oldsstate = info->sstate; | |
576 | oldcstate = info->cstate; | |
577 | ||
578 | spin_lock_bh(&nf_pptp_lock); | |
579 | ||
580 | /* FIXME: We just blindly assume that the control connection is always | |
581 | * established from PNS->PAC. However, RFC makes no guarantee */ | |
582 | if (dir == IP_CT_DIR_ORIGINAL) | |
583 | /* client -> server (PNS -> PAC) */ | |
051966c0 | 584 | ret = pptp_outbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct, |
f09943fe PM |
585 | ctinfo); |
586 | else | |
587 | /* server -> client (PAC -> PNS) */ | |
051966c0 | 588 | ret = pptp_inbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct, |
f09943fe | 589 | ctinfo); |
0d53778e PM |
590 | pr_debug("sstate: %d->%d, cstate: %d->%d\n", |
591 | oldsstate, info->sstate, oldcstate, info->cstate); | |
f09943fe PM |
592 | spin_unlock_bh(&nf_pptp_lock); |
593 | ||
594 | return ret; | |
595 | } | |
596 | ||
6002f266 PM |
597 | static const struct nf_conntrack_expect_policy pptp_exp_policy = { |
598 | .max_expected = 2, | |
599 | .timeout = 5 * 60, | |
600 | }; | |
601 | ||
f09943fe PM |
602 | /* control protocol helper */ |
603 | static struct nf_conntrack_helper pptp __read_mostly = { | |
604 | .name = "pptp", | |
605 | .me = THIS_MODULE, | |
f09943fe | 606 | .tuple.src.l3num = AF_INET, |
09640e63 | 607 | .tuple.src.u.tcp.port = cpu_to_be16(PPTP_CONTROL_PORT), |
f09943fe | 608 | .tuple.dst.protonum = IPPROTO_TCP, |
f09943fe PM |
609 | .help = conntrack_pptp_help, |
610 | .destroy = pptp_destroy_siblings, | |
6002f266 | 611 | .expect_policy = &pptp_exp_policy, |
f09943fe PM |
612 | }; |
613 | ||
614 | static int __init nf_conntrack_pptp_init(void) | |
615 | { | |
dcf67740 FW |
616 | NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_pptp_master)); |
617 | ||
8142b227 | 618 | return nf_conntrack_helper_register(&pptp); |
f09943fe PM |
619 | } |
620 | ||
621 | static void __exit nf_conntrack_pptp_fini(void) | |
622 | { | |
623 | nf_conntrack_helper_unregister(&pptp); | |
f09943fe PM |
624 | } |
625 | ||
626 | module_init(nf_conntrack_pptp_init); | |
627 | module_exit(nf_conntrack_pptp_fini); |