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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"); | |
4dc06f96 | 40 | MODULE_ALIAS_NFCT_HELPER("pptp"); |
f09943fe PM |
41 | |
42 | static DEFINE_SPINLOCK(nf_pptp_lock); | |
43 | ||
44 | int | |
3db05fea | 45 | (*nf_nat_pptp_hook_outbound)(struct sk_buff *skb, |
f09943fe PM |
46 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
47 | struct PptpControlHeader *ctlh, | |
48 | union pptp_ctrl_union *pptpReq) __read_mostly; | |
49 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_outbound); | |
50 | ||
51 | int | |
3db05fea | 52 | (*nf_nat_pptp_hook_inbound)(struct sk_buff *skb, |
f09943fe PM |
53 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
54 | struct PptpControlHeader *ctlh, | |
55 | union pptp_ctrl_union *pptpReq) __read_mostly; | |
56 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_inbound); | |
57 | ||
58 | void | |
59 | (*nf_nat_pptp_hook_exp_gre)(struct nf_conntrack_expect *expect_orig, | |
60 | struct nf_conntrack_expect *expect_reply) | |
61 | __read_mostly; | |
62 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_exp_gre); | |
63 | ||
64 | void | |
65 | (*nf_nat_pptp_hook_expectfn)(struct nf_conn *ct, | |
66 | struct nf_conntrack_expect *exp) __read_mostly; | |
67 | EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn); | |
68 | ||
346e15be | 69 | #if defined(DEBUG) || defined(CONFIG_DYNAMIC_PRINTK_DEBUG) |
f09943fe | 70 | /* PptpControlMessageType names */ |
9ddd0ed0 | 71 | const char *const pptp_msg_name[] = { |
f09943fe PM |
72 | "UNKNOWN_MESSAGE", |
73 | "START_SESSION_REQUEST", | |
74 | "START_SESSION_REPLY", | |
75 | "STOP_SESSION_REQUEST", | |
76 | "STOP_SESSION_REPLY", | |
77 | "ECHO_REQUEST", | |
78 | "ECHO_REPLY", | |
79 | "OUT_CALL_REQUEST", | |
80 | "OUT_CALL_REPLY", | |
81 | "IN_CALL_REQUEST", | |
82 | "IN_CALL_REPLY", | |
83 | "IN_CALL_CONNECT", | |
84 | "CALL_CLEAR_REQUEST", | |
85 | "CALL_DISCONNECT_NOTIFY", | |
86 | "WAN_ERROR_NOTIFY", | |
87 | "SET_LINK_INFO" | |
88 | }; | |
89 | EXPORT_SYMBOL(pptp_msg_name); | |
f09943fe PM |
90 | #endif |
91 | ||
92 | #define SECS *HZ | |
93 | #define MINS * 60 SECS | |
94 | #define HOURS * 60 MINS | |
95 | ||
96 | #define PPTP_GRE_TIMEOUT (10 MINS) | |
97 | #define PPTP_GRE_STREAM_TIMEOUT (5 HOURS) | |
98 | ||
99 | static void pptp_expectfn(struct nf_conn *ct, | |
100 | struct nf_conntrack_expect *exp) | |
101 | { | |
0e6e75af | 102 | struct net *net = nf_ct_net(ct); |
f09943fe | 103 | typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn; |
0d53778e | 104 | pr_debug("increasing timeouts\n"); |
f09943fe PM |
105 | |
106 | /* increase timeout of GRE data channel conntrack entry */ | |
107 | ct->proto.gre.timeout = PPTP_GRE_TIMEOUT; | |
108 | ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT; | |
109 | ||
110 | /* Can you see how rusty this code is, compared with the pre-2.6.11 | |
111 | * one? That's what happened to my shiny newnat of 2002 ;( -HW */ | |
112 | ||
113 | rcu_read_lock(); | |
114 | nf_nat_pptp_expectfn = rcu_dereference(nf_nat_pptp_hook_expectfn); | |
7399072a | 115 | if (nf_nat_pptp_expectfn && ct->master->status & IPS_NAT_MASK) |
f09943fe PM |
116 | nf_nat_pptp_expectfn(ct, exp); |
117 | else { | |
118 | struct nf_conntrack_tuple inv_t; | |
119 | struct nf_conntrack_expect *exp_other; | |
120 | ||
121 | /* obviously this tuple inversion only works until you do NAT */ | |
122 | nf_ct_invert_tuplepr(&inv_t, &exp->tuple); | |
0d53778e | 123 | pr_debug("trying to unexpect other dir: "); |
3c9fba65 | 124 | nf_ct_dump_tuple(&inv_t); |
f09943fe | 125 | |
0e6e75af | 126 | exp_other = nf_ct_expect_find_get(net, &inv_t); |
f09943fe PM |
127 | if (exp_other) { |
128 | /* delete other expectation. */ | |
0d53778e | 129 | pr_debug("found\n"); |
6823645d PM |
130 | nf_ct_unexpect_related(exp_other); |
131 | nf_ct_expect_put(exp_other); | |
f09943fe | 132 | } else { |
0d53778e | 133 | pr_debug("not found\n"); |
f09943fe PM |
134 | } |
135 | } | |
136 | rcu_read_unlock(); | |
137 | } | |
138 | ||
0e6e75af AD |
139 | static int destroy_sibling_or_exp(struct net *net, |
140 | const struct nf_conntrack_tuple *t) | |
f09943fe | 141 | { |
9ddd0ed0 | 142 | const struct nf_conntrack_tuple_hash *h; |
f09943fe PM |
143 | struct nf_conntrack_expect *exp; |
144 | struct nf_conn *sibling; | |
145 | ||
0d53778e | 146 | pr_debug("trying to timeout ct or exp for tuple "); |
3c9fba65 | 147 | nf_ct_dump_tuple(t); |
f09943fe | 148 | |
0e6e75af | 149 | h = nf_conntrack_find_get(net, t); |
f09943fe PM |
150 | if (h) { |
151 | sibling = nf_ct_tuplehash_to_ctrack(h); | |
0d53778e | 152 | pr_debug("setting timeout of conntrack %p to 0\n", sibling); |
f09943fe PM |
153 | sibling->proto.gre.timeout = 0; |
154 | sibling->proto.gre.stream_timeout = 0; | |
155 | if (del_timer(&sibling->timeout)) | |
156 | sibling->timeout.function((unsigned long)sibling); | |
157 | nf_ct_put(sibling); | |
158 | return 1; | |
159 | } else { | |
0e6e75af | 160 | exp = nf_ct_expect_find_get(net, t); |
f09943fe | 161 | if (exp) { |
0d53778e | 162 | pr_debug("unexpect_related of expect %p\n", exp); |
6823645d PM |
163 | nf_ct_unexpect_related(exp); |
164 | nf_ct_expect_put(exp); | |
f09943fe PM |
165 | return 1; |
166 | } | |
167 | } | |
168 | return 0; | |
169 | } | |
170 | ||
171 | /* timeout GRE data connections */ | |
172 | static void pptp_destroy_siblings(struct nf_conn *ct) | |
173 | { | |
0e6e75af | 174 | struct net *net = nf_ct_net(ct); |
9ddd0ed0 | 175 | const struct nf_conn_help *help = nfct_help(ct); |
f09943fe PM |
176 | struct nf_conntrack_tuple t; |
177 | ||
178 | nf_ct_gre_keymap_destroy(ct); | |
179 | ||
180 | /* try original (pns->pac) tuple */ | |
181 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t)); | |
182 | t.dst.protonum = IPPROTO_GRE; | |
183 | t.src.u.gre.key = help->help.ct_pptp_info.pns_call_id; | |
184 | t.dst.u.gre.key = help->help.ct_pptp_info.pac_call_id; | |
0e6e75af | 185 | if (!destroy_sibling_or_exp(net, &t)) |
0d53778e | 186 | pr_debug("failed to timeout original pns->pac ct/exp\n"); |
f09943fe PM |
187 | |
188 | /* try reply (pac->pns) tuple */ | |
189 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t)); | |
190 | t.dst.protonum = IPPROTO_GRE; | |
191 | t.src.u.gre.key = help->help.ct_pptp_info.pac_call_id; | |
192 | t.dst.u.gre.key = help->help.ct_pptp_info.pns_call_id; | |
0e6e75af | 193 | if (!destroy_sibling_or_exp(net, &t)) |
0d53778e | 194 | pr_debug("failed to timeout reply pac->pns ct/exp\n"); |
f09943fe PM |
195 | } |
196 | ||
197 | /* expect GRE connections (PNS->PAC and PAC->PNS direction) */ | |
198 | static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid) | |
199 | { | |
200 | struct nf_conntrack_expect *exp_orig, *exp_reply; | |
201 | enum ip_conntrack_dir dir; | |
202 | int ret = 1; | |
203 | typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre; | |
204 | ||
6823645d | 205 | exp_orig = nf_ct_expect_alloc(ct); |
f09943fe PM |
206 | if (exp_orig == NULL) |
207 | goto out; | |
208 | ||
6823645d | 209 | exp_reply = nf_ct_expect_alloc(ct); |
f09943fe PM |
210 | if (exp_reply == NULL) |
211 | goto out_put_orig; | |
212 | ||
213 | /* original direction, PNS->PAC */ | |
214 | dir = IP_CT_DIR_ORIGINAL; | |
6002f266 | 215 | nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT, |
5e8fbe2a | 216 | nf_ct_l3num(ct), |
6823645d PM |
217 | &ct->tuplehash[dir].tuple.src.u3, |
218 | &ct->tuplehash[dir].tuple.dst.u3, | |
219 | IPPROTO_GRE, &peer_callid, &callid); | |
f09943fe PM |
220 | exp_orig->expectfn = pptp_expectfn; |
221 | ||
222 | /* reply direction, PAC->PNS */ | |
223 | dir = IP_CT_DIR_REPLY; | |
6002f266 | 224 | nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT, |
5e8fbe2a | 225 | nf_ct_l3num(ct), |
6823645d PM |
226 | &ct->tuplehash[dir].tuple.src.u3, |
227 | &ct->tuplehash[dir].tuple.dst.u3, | |
228 | IPPROTO_GRE, &callid, &peer_callid); | |
f09943fe PM |
229 | exp_reply->expectfn = pptp_expectfn; |
230 | ||
231 | nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre); | |
232 | if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK) | |
233 | nf_nat_pptp_exp_gre(exp_orig, exp_reply); | |
6823645d | 234 | if (nf_ct_expect_related(exp_orig) != 0) |
f09943fe | 235 | goto out_put_both; |
6823645d | 236 | if (nf_ct_expect_related(exp_reply) != 0) |
f09943fe PM |
237 | goto out_unexpect_orig; |
238 | ||
239 | /* Add GRE keymap entries */ | |
240 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0) | |
241 | goto out_unexpect_both; | |
242 | if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) { | |
243 | nf_ct_gre_keymap_destroy(ct); | |
244 | goto out_unexpect_both; | |
245 | } | |
246 | ret = 0; | |
247 | ||
248 | out_put_both: | |
6823645d | 249 | nf_ct_expect_put(exp_reply); |
f09943fe | 250 | out_put_orig: |
6823645d | 251 | nf_ct_expect_put(exp_orig); |
f09943fe PM |
252 | out: |
253 | return ret; | |
254 | ||
255 | out_unexpect_both: | |
6823645d | 256 | nf_ct_unexpect_related(exp_reply); |
f09943fe | 257 | out_unexpect_orig: |
6823645d | 258 | nf_ct_unexpect_related(exp_orig); |
f09943fe PM |
259 | goto out_put_both; |
260 | } | |
261 | ||
262 | static inline int | |
3db05fea | 263 | pptp_inbound_pkt(struct sk_buff *skb, |
f09943fe PM |
264 | struct PptpControlHeader *ctlh, |
265 | union pptp_ctrl_union *pptpReq, | |
266 | unsigned int reqlen, | |
267 | struct nf_conn *ct, | |
268 | enum ip_conntrack_info ctinfo) | |
269 | { | |
270 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
271 | u_int16_t msg; | |
272 | __be16 cid = 0, pcid = 0; | |
273 | typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound; | |
274 | ||
275 | msg = ntohs(ctlh->messageType); | |
0d53778e | 276 | pr_debug("inbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
277 | |
278 | switch (msg) { | |
279 | case PPTP_START_SESSION_REPLY: | |
280 | /* server confirms new control session */ | |
281 | if (info->sstate < PPTP_SESSION_REQUESTED) | |
282 | goto invalid; | |
283 | if (pptpReq->srep.resultCode == PPTP_START_OK) | |
284 | info->sstate = PPTP_SESSION_CONFIRMED; | |
285 | else | |
286 | info->sstate = PPTP_SESSION_ERROR; | |
287 | break; | |
288 | ||
289 | case PPTP_STOP_SESSION_REPLY: | |
290 | /* server confirms end of control session */ | |
291 | if (info->sstate > PPTP_SESSION_STOPREQ) | |
292 | goto invalid; | |
293 | if (pptpReq->strep.resultCode == PPTP_STOP_OK) | |
294 | info->sstate = PPTP_SESSION_NONE; | |
295 | else | |
296 | info->sstate = PPTP_SESSION_ERROR; | |
297 | break; | |
298 | ||
299 | case PPTP_OUT_CALL_REPLY: | |
300 | /* server accepted call, we now expect GRE frames */ | |
301 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
302 | goto invalid; | |
303 | if (info->cstate != PPTP_CALL_OUT_REQ && | |
304 | info->cstate != PPTP_CALL_OUT_CONF) | |
305 | goto invalid; | |
306 | ||
307 | cid = pptpReq->ocack.callID; | |
308 | pcid = pptpReq->ocack.peersCallID; | |
309 | if (info->pns_call_id != pcid) | |
310 | goto invalid; | |
0d53778e PM |
311 | pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], |
312 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
313 | |
314 | if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) { | |
315 | info->cstate = PPTP_CALL_OUT_CONF; | |
316 | info->pac_call_id = cid; | |
317 | exp_gre(ct, cid, pcid); | |
318 | } else | |
319 | info->cstate = PPTP_CALL_NONE; | |
320 | break; | |
321 | ||
322 | case PPTP_IN_CALL_REQUEST: | |
323 | /* server tells us about incoming call request */ | |
324 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
325 | goto invalid; | |
326 | ||
327 | cid = pptpReq->icreq.callID; | |
0d53778e | 328 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
329 | info->cstate = PPTP_CALL_IN_REQ; |
330 | info->pac_call_id = cid; | |
331 | break; | |
332 | ||
333 | case PPTP_IN_CALL_CONNECT: | |
334 | /* server tells us about incoming call established */ | |
335 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
336 | goto invalid; | |
337 | if (info->cstate != PPTP_CALL_IN_REP && | |
338 | info->cstate != PPTP_CALL_IN_CONF) | |
339 | goto invalid; | |
340 | ||
341 | pcid = pptpReq->iccon.peersCallID; | |
342 | cid = info->pac_call_id; | |
343 | ||
344 | if (info->pns_call_id != pcid) | |
345 | goto invalid; | |
346 | ||
0d53778e | 347 | pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid)); |
f09943fe PM |
348 | info->cstate = PPTP_CALL_IN_CONF; |
349 | ||
350 | /* we expect a GRE connection from PAC to PNS */ | |
351 | exp_gre(ct, cid, pcid); | |
352 | break; | |
353 | ||
354 | case PPTP_CALL_DISCONNECT_NOTIFY: | |
355 | /* server confirms disconnect */ | |
356 | cid = pptpReq->disc.callID; | |
0d53778e | 357 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
358 | info->cstate = PPTP_CALL_NONE; |
359 | ||
360 | /* untrack this call id, unexpect GRE packets */ | |
361 | pptp_destroy_siblings(ct); | |
362 | break; | |
363 | ||
364 | case PPTP_WAN_ERROR_NOTIFY: | |
365 | case PPTP_ECHO_REQUEST: | |
366 | case PPTP_ECHO_REPLY: | |
367 | /* I don't have to explain these ;) */ | |
368 | break; | |
369 | ||
370 | default: | |
371 | goto invalid; | |
372 | } | |
373 | ||
374 | nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound); | |
375 | if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK) | |
3db05fea | 376 | return nf_nat_pptp_inbound(skb, ct, ctinfo, ctlh, pptpReq); |
f09943fe PM |
377 | return NF_ACCEPT; |
378 | ||
379 | invalid: | |
0d53778e PM |
380 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
381 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
382 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
383 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
384 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
385 | return NF_ACCEPT; |
386 | } | |
387 | ||
388 | static inline int | |
3db05fea | 389 | pptp_outbound_pkt(struct sk_buff *skb, |
f09943fe PM |
390 | struct PptpControlHeader *ctlh, |
391 | union pptp_ctrl_union *pptpReq, | |
392 | unsigned int reqlen, | |
393 | struct nf_conn *ct, | |
394 | enum ip_conntrack_info ctinfo) | |
395 | { | |
396 | struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; | |
397 | u_int16_t msg; | |
398 | __be16 cid = 0, pcid = 0; | |
399 | typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound; | |
400 | ||
401 | msg = ntohs(ctlh->messageType); | |
0d53778e | 402 | pr_debug("outbound control message %s\n", pptp_msg_name[msg]); |
f09943fe PM |
403 | |
404 | switch (msg) { | |
405 | case PPTP_START_SESSION_REQUEST: | |
406 | /* client requests for new control session */ | |
407 | if (info->sstate != PPTP_SESSION_NONE) | |
408 | goto invalid; | |
409 | info->sstate = PPTP_SESSION_REQUESTED; | |
410 | break; | |
411 | ||
412 | case PPTP_STOP_SESSION_REQUEST: | |
413 | /* client requests end of control session */ | |
414 | info->sstate = PPTP_SESSION_STOPREQ; | |
415 | break; | |
416 | ||
417 | case PPTP_OUT_CALL_REQUEST: | |
418 | /* client initiating connection to server */ | |
419 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
420 | goto invalid; | |
421 | info->cstate = PPTP_CALL_OUT_REQ; | |
422 | /* track PNS call id */ | |
423 | cid = pptpReq->ocreq.callID; | |
0d53778e | 424 | pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); |
f09943fe PM |
425 | info->pns_call_id = cid; |
426 | break; | |
427 | ||
428 | case PPTP_IN_CALL_REPLY: | |
429 | /* client answers incoming call */ | |
430 | if (info->cstate != PPTP_CALL_IN_REQ && | |
431 | info->cstate != PPTP_CALL_IN_REP) | |
432 | goto invalid; | |
433 | ||
434 | cid = pptpReq->icack.callID; | |
435 | pcid = pptpReq->icack.peersCallID; | |
436 | if (info->pac_call_id != pcid) | |
437 | goto invalid; | |
0d53778e PM |
438 | pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg], |
439 | ntohs(cid), ntohs(pcid)); | |
f09943fe PM |
440 | |
441 | if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) { | |
442 | /* part two of the three-way handshake */ | |
443 | info->cstate = PPTP_CALL_IN_REP; | |
444 | info->pns_call_id = cid; | |
445 | } else | |
446 | info->cstate = PPTP_CALL_NONE; | |
447 | break; | |
448 | ||
449 | case PPTP_CALL_CLEAR_REQUEST: | |
450 | /* client requests hangup of call */ | |
451 | if (info->sstate != PPTP_SESSION_CONFIRMED) | |
452 | goto invalid; | |
453 | /* FUTURE: iterate over all calls and check if | |
454 | * call ID is valid. We don't do this without newnat, | |
455 | * because we only know about last call */ | |
456 | info->cstate = PPTP_CALL_CLEAR_REQ; | |
457 | break; | |
458 | ||
459 | case PPTP_SET_LINK_INFO: | |
460 | case PPTP_ECHO_REQUEST: | |
461 | case PPTP_ECHO_REPLY: | |
462 | /* I don't have to explain these ;) */ | |
463 | break; | |
464 | ||
465 | default: | |
466 | goto invalid; | |
467 | } | |
468 | ||
469 | nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound); | |
470 | if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK) | |
3db05fea | 471 | return nf_nat_pptp_outbound(skb, ct, ctinfo, ctlh, pptpReq); |
f09943fe PM |
472 | return NF_ACCEPT; |
473 | ||
474 | invalid: | |
0d53778e PM |
475 | pr_debug("invalid %s: type=%d cid=%u pcid=%u " |
476 | "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", | |
477 | msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], | |
478 | msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, | |
479 | ntohs(info->pns_call_id), ntohs(info->pac_call_id)); | |
f09943fe PM |
480 | return NF_ACCEPT; |
481 | } | |
482 | ||
483 | static const unsigned int pptp_msg_size[] = { | |
484 | [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest), | |
485 | [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply), | |
486 | [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest), | |
487 | [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply), | |
488 | [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest), | |
489 | [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply), | |
490 | [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest), | |
491 | [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply), | |
492 | [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected), | |
493 | [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest), | |
494 | [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify), | |
495 | [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify), | |
496 | [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo), | |
497 | }; | |
498 | ||
499 | /* track caller id inside control connection, call expect_related */ | |
500 | static int | |
3db05fea | 501 | conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff, |
f09943fe PM |
502 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
503 | ||
504 | { | |
505 | int dir = CTINFO2DIR(ctinfo); | |
9ddd0ed0 JE |
506 | const struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; |
507 | const struct tcphdr *tcph; | |
508 | struct tcphdr _tcph; | |
509 | const struct pptp_pkt_hdr *pptph; | |
510 | struct pptp_pkt_hdr _pptph; | |
f09943fe PM |
511 | struct PptpControlHeader _ctlh, *ctlh; |
512 | union pptp_ctrl_union _pptpReq, *pptpReq; | |
3db05fea | 513 | unsigned int tcplen = skb->len - protoff; |
f09943fe PM |
514 | unsigned int datalen, reqlen, nexthdr_off; |
515 | int oldsstate, oldcstate; | |
516 | int ret; | |
517 | u_int16_t msg; | |
518 | ||
519 | /* don't do any tracking before tcp handshake complete */ | |
520 | if (ctinfo != IP_CT_ESTABLISHED && | |
521 | ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) | |
522 | return NF_ACCEPT; | |
523 | ||
524 | nexthdr_off = protoff; | |
3db05fea | 525 | tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph); |
f09943fe PM |
526 | BUG_ON(!tcph); |
527 | nexthdr_off += tcph->doff * 4; | |
601e68e1 | 528 | datalen = tcplen - tcph->doff * 4; |
f09943fe | 529 | |
3db05fea | 530 | pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph); |
f09943fe | 531 | if (!pptph) { |
0d53778e | 532 | pr_debug("no full PPTP header, can't track\n"); |
f09943fe PM |
533 | return NF_ACCEPT; |
534 | } | |
535 | nexthdr_off += sizeof(_pptph); | |
536 | datalen -= sizeof(_pptph); | |
537 | ||
538 | /* if it's not a control message we can't do anything with it */ | |
539 | if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL || | |
540 | ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) { | |
0d53778e | 541 | pr_debug("not a control packet\n"); |
f09943fe PM |
542 | return NF_ACCEPT; |
543 | } | |
544 | ||
3db05fea | 545 | ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh); |
f09943fe PM |
546 | if (!ctlh) |
547 | return NF_ACCEPT; | |
548 | nexthdr_off += sizeof(_ctlh); | |
549 | datalen -= sizeof(_ctlh); | |
550 | ||
551 | reqlen = datalen; | |
552 | msg = ntohs(ctlh->messageType); | |
553 | if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg]) | |
554 | return NF_ACCEPT; | |
555 | if (reqlen > sizeof(*pptpReq)) | |
556 | reqlen = sizeof(*pptpReq); | |
557 | ||
3db05fea | 558 | pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq); |
f09943fe PM |
559 | if (!pptpReq) |
560 | return NF_ACCEPT; | |
561 | ||
562 | oldsstate = info->sstate; | |
563 | oldcstate = info->cstate; | |
564 | ||
565 | spin_lock_bh(&nf_pptp_lock); | |
566 | ||
567 | /* FIXME: We just blindly assume that the control connection is always | |
568 | * established from PNS->PAC. However, RFC makes no guarantee */ | |
569 | if (dir == IP_CT_DIR_ORIGINAL) | |
570 | /* client -> server (PNS -> PAC) */ | |
3db05fea | 571 | ret = pptp_outbound_pkt(skb, ctlh, pptpReq, reqlen, ct, |
f09943fe PM |
572 | ctinfo); |
573 | else | |
574 | /* server -> client (PAC -> PNS) */ | |
3db05fea | 575 | ret = pptp_inbound_pkt(skb, ctlh, pptpReq, reqlen, ct, |
f09943fe | 576 | ctinfo); |
0d53778e PM |
577 | pr_debug("sstate: %d->%d, cstate: %d->%d\n", |
578 | oldsstate, info->sstate, oldcstate, info->cstate); | |
f09943fe PM |
579 | spin_unlock_bh(&nf_pptp_lock); |
580 | ||
581 | return ret; | |
582 | } | |
583 | ||
6002f266 PM |
584 | static const struct nf_conntrack_expect_policy pptp_exp_policy = { |
585 | .max_expected = 2, | |
586 | .timeout = 5 * 60, | |
587 | }; | |
588 | ||
f09943fe PM |
589 | /* control protocol helper */ |
590 | static struct nf_conntrack_helper pptp __read_mostly = { | |
591 | .name = "pptp", | |
592 | .me = THIS_MODULE, | |
f09943fe PM |
593 | .tuple.src.l3num = AF_INET, |
594 | .tuple.src.u.tcp.port = __constant_htons(PPTP_CONTROL_PORT), | |
595 | .tuple.dst.protonum = IPPROTO_TCP, | |
f09943fe PM |
596 | .help = conntrack_pptp_help, |
597 | .destroy = pptp_destroy_siblings, | |
6002f266 | 598 | .expect_policy = &pptp_exp_policy, |
f09943fe PM |
599 | }; |
600 | ||
0e6e75af AD |
601 | static void nf_conntrack_pptp_net_exit(struct net *net) |
602 | { | |
603 | nf_ct_gre_keymap_flush(net); | |
604 | } | |
605 | ||
606 | static struct pernet_operations nf_conntrack_pptp_net_ops = { | |
607 | .exit = nf_conntrack_pptp_net_exit, | |
608 | }; | |
609 | ||
f09943fe PM |
610 | static int __init nf_conntrack_pptp_init(void) |
611 | { | |
0e6e75af AD |
612 | int rv; |
613 | ||
614 | rv = nf_conntrack_helper_register(&pptp); | |
615 | if (rv < 0) | |
616 | return rv; | |
617 | rv = register_pernet_subsys(&nf_conntrack_pptp_net_ops); | |
618 | if (rv < 0) | |
619 | nf_conntrack_helper_unregister(&pptp); | |
620 | return rv; | |
f09943fe PM |
621 | } |
622 | ||
623 | static void __exit nf_conntrack_pptp_fini(void) | |
624 | { | |
625 | nf_conntrack_helper_unregister(&pptp); | |
0e6e75af | 626 | unregister_pernet_subsys(&nf_conntrack_pptp_net_ops); |
f09943fe PM |
627 | } |
628 | ||
629 | module_init(nf_conntrack_pptp_init); | |
630 | module_exit(nf_conntrack_pptp_fini); |