1 /* 2 * Connection tracking support for PPTP (Point to Point Tunneling Protocol). 3 * PPTP is a a protocol for creating virtual private networks. 4 * It is a specification defined by Microsoft and some vendors 5 * working with Microsoft. PPTP is built on top of a modified 6 * version of the Internet Generic Routing Encapsulation Protocol. 7 * GRE is defined in RFC 1701 and RFC 1702. Documentation of 8 * PPTP can be found in RFC 2637 9 * 10 * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org> 11 * 12 * Development of this code funded by Astaro AG (http://www.astaro.com/) 13 * 14 * Limitations: 15 * - We blindly assume that control connections are always 16 * established in PNS->PAC direction. This is a violation 17 * of RFFC2673 18 * - We can only support one single call within each session 19 * TODO: 20 * - testing of incoming PPTP calls 21 */ 22 23 #include <linux/module.h> 24 #include <linux/skbuff.h> 25 #include <linux/in.h> 26 #include <linux/tcp.h> 27 28 #include <net/netfilter/nf_conntrack.h> 29 #include <net/netfilter/nf_conntrack_core.h> 30 #include <net/netfilter/nf_conntrack_helper.h> 31 #include <linux/netfilter/nf_conntrack_proto_gre.h> 32 #include <linux/netfilter/nf_conntrack_pptp.h> 33 34 #define NF_CT_PPTP_VERSION "3.1" 35 36 MODULE_LICENSE("GPL"); 37 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); 38 MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP"); 39 MODULE_ALIAS("ip_conntrack_pptp"); 40 41 static DEFINE_SPINLOCK(nf_pptp_lock); 42 43 int 44 (*nf_nat_pptp_hook_outbound)(struct sk_buff *skb, 45 struct nf_conn *ct, enum ip_conntrack_info ctinfo, 46 struct PptpControlHeader *ctlh, 47 union pptp_ctrl_union *pptpReq) __read_mostly; 48 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_outbound); 49 50 int 51 (*nf_nat_pptp_hook_inbound)(struct sk_buff *skb, 52 struct nf_conn *ct, enum ip_conntrack_info ctinfo, 53 struct PptpControlHeader *ctlh, 54 union pptp_ctrl_union *pptpReq) __read_mostly; 55 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_inbound); 56 57 void 58 (*nf_nat_pptp_hook_exp_gre)(struct nf_conntrack_expect *expect_orig, 59 struct nf_conntrack_expect *expect_reply) 60 __read_mostly; 61 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_exp_gre); 62 63 void 64 (*nf_nat_pptp_hook_expectfn)(struct nf_conn *ct, 65 struct nf_conntrack_expect *exp) __read_mostly; 66 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn); 67 68 #ifdef DEBUG 69 /* PptpControlMessageType names */ 70 const char *const pptp_msg_name[] = { 71 "UNKNOWN_MESSAGE", 72 "START_SESSION_REQUEST", 73 "START_SESSION_REPLY", 74 "STOP_SESSION_REQUEST", 75 "STOP_SESSION_REPLY", 76 "ECHO_REQUEST", 77 "ECHO_REPLY", 78 "OUT_CALL_REQUEST", 79 "OUT_CALL_REPLY", 80 "IN_CALL_REQUEST", 81 "IN_CALL_REPLY", 82 "IN_CALL_CONNECT", 83 "CALL_CLEAR_REQUEST", 84 "CALL_DISCONNECT_NOTIFY", 85 "WAN_ERROR_NOTIFY", 86 "SET_LINK_INFO" 87 }; 88 EXPORT_SYMBOL(pptp_msg_name); 89 #endif 90 91 #define SECS *HZ 92 #define MINS * 60 SECS 93 #define HOURS * 60 MINS 94 95 #define PPTP_GRE_TIMEOUT (10 MINS) 96 #define PPTP_GRE_STREAM_TIMEOUT (5 HOURS) 97 98 static void pptp_expectfn(struct nf_conn *ct, 99 struct nf_conntrack_expect *exp) 100 { 101 typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn; 102 pr_debug("increasing timeouts\n"); 103 104 /* increase timeout of GRE data channel conntrack entry */ 105 ct->proto.gre.timeout = PPTP_GRE_TIMEOUT; 106 ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT; 107 108 /* Can you see how rusty this code is, compared with the pre-2.6.11 109 * one? That's what happened to my shiny newnat of 2002 ;( -HW */ 110 111 rcu_read_lock(); 112 nf_nat_pptp_expectfn = rcu_dereference(nf_nat_pptp_hook_expectfn); 113 if (nf_nat_pptp_expectfn && ct->master->status & IPS_NAT_MASK) 114 nf_nat_pptp_expectfn(ct, exp); 115 else { 116 struct nf_conntrack_tuple inv_t; 117 struct nf_conntrack_expect *exp_other; 118 119 /* obviously this tuple inversion only works until you do NAT */ 120 nf_ct_invert_tuplepr(&inv_t, &exp->tuple); 121 pr_debug("trying to unexpect other dir: "); 122 NF_CT_DUMP_TUPLE(&inv_t); 123 124 exp_other = nf_ct_expect_find_get(&inv_t); 125 if (exp_other) { 126 /* delete other expectation. */ 127 pr_debug("found\n"); 128 nf_ct_unexpect_related(exp_other); 129 nf_ct_expect_put(exp_other); 130 } else { 131 pr_debug("not found\n"); 132 } 133 } 134 rcu_read_unlock(); 135 } 136 137 static int destroy_sibling_or_exp(const struct nf_conntrack_tuple *t) 138 { 139 const struct nf_conntrack_tuple_hash *h; 140 struct nf_conntrack_expect *exp; 141 struct nf_conn *sibling; 142 143 pr_debug("trying to timeout ct or exp for tuple "); 144 NF_CT_DUMP_TUPLE(t); 145 146 h = nf_conntrack_find_get(t); 147 if (h) { 148 sibling = nf_ct_tuplehash_to_ctrack(h); 149 pr_debug("setting timeout of conntrack %p to 0\n", sibling); 150 sibling->proto.gre.timeout = 0; 151 sibling->proto.gre.stream_timeout = 0; 152 if (del_timer(&sibling->timeout)) 153 sibling->timeout.function((unsigned long)sibling); 154 nf_ct_put(sibling); 155 return 1; 156 } else { 157 exp = nf_ct_expect_find_get(t); 158 if (exp) { 159 pr_debug("unexpect_related of expect %p\n", exp); 160 nf_ct_unexpect_related(exp); 161 nf_ct_expect_put(exp); 162 return 1; 163 } 164 } 165 return 0; 166 } 167 168 /* timeout GRE data connections */ 169 static void pptp_destroy_siblings(struct nf_conn *ct) 170 { 171 const struct nf_conn_help *help = nfct_help(ct); 172 struct nf_conntrack_tuple t; 173 174 nf_ct_gre_keymap_destroy(ct); 175 176 /* try original (pns->pac) tuple */ 177 memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t)); 178 t.dst.protonum = IPPROTO_GRE; 179 t.src.u.gre.key = help->help.ct_pptp_info.pns_call_id; 180 t.dst.u.gre.key = help->help.ct_pptp_info.pac_call_id; 181 if (!destroy_sibling_or_exp(&t)) 182 pr_debug("failed to timeout original pns->pac ct/exp\n"); 183 184 /* try reply (pac->pns) tuple */ 185 memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t)); 186 t.dst.protonum = IPPROTO_GRE; 187 t.src.u.gre.key = help->help.ct_pptp_info.pac_call_id; 188 t.dst.u.gre.key = help->help.ct_pptp_info.pns_call_id; 189 if (!destroy_sibling_or_exp(&t)) 190 pr_debug("failed to timeout reply pac->pns ct/exp\n"); 191 } 192 193 /* expect GRE connections (PNS->PAC and PAC->PNS direction) */ 194 static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid) 195 { 196 struct nf_conntrack_expect *exp_orig, *exp_reply; 197 enum ip_conntrack_dir dir; 198 int ret = 1; 199 typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre; 200 201 exp_orig = nf_ct_expect_alloc(ct); 202 if (exp_orig == NULL) 203 goto out; 204 205 exp_reply = nf_ct_expect_alloc(ct); 206 if (exp_reply == NULL) 207 goto out_put_orig; 208 209 /* original direction, PNS->PAC */ 210 dir = IP_CT_DIR_ORIGINAL; 211 nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT, 212 ct->tuplehash[dir].tuple.src.l3num, 213 &ct->tuplehash[dir].tuple.src.u3, 214 &ct->tuplehash[dir].tuple.dst.u3, 215 IPPROTO_GRE, &peer_callid, &callid); 216 exp_orig->expectfn = pptp_expectfn; 217 218 /* reply direction, PAC->PNS */ 219 dir = IP_CT_DIR_REPLY; 220 nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT, 221 ct->tuplehash[dir].tuple.src.l3num, 222 &ct->tuplehash[dir].tuple.src.u3, 223 &ct->tuplehash[dir].tuple.dst.u3, 224 IPPROTO_GRE, &callid, &peer_callid); 225 exp_reply->expectfn = pptp_expectfn; 226 227 nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre); 228 if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK) 229 nf_nat_pptp_exp_gre(exp_orig, exp_reply); 230 if (nf_ct_expect_related(exp_orig) != 0) 231 goto out_put_both; 232 if (nf_ct_expect_related(exp_reply) != 0) 233 goto out_unexpect_orig; 234 235 /* Add GRE keymap entries */ 236 if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0) 237 goto out_unexpect_both; 238 if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) { 239 nf_ct_gre_keymap_destroy(ct); 240 goto out_unexpect_both; 241 } 242 ret = 0; 243 244 out_put_both: 245 nf_ct_expect_put(exp_reply); 246 out_put_orig: 247 nf_ct_expect_put(exp_orig); 248 out: 249 return ret; 250 251 out_unexpect_both: 252 nf_ct_unexpect_related(exp_reply); 253 out_unexpect_orig: 254 nf_ct_unexpect_related(exp_orig); 255 goto out_put_both; 256 } 257 258 static inline int 259 pptp_inbound_pkt(struct sk_buff *skb, 260 struct PptpControlHeader *ctlh, 261 union pptp_ctrl_union *pptpReq, 262 unsigned int reqlen, 263 struct nf_conn *ct, 264 enum ip_conntrack_info ctinfo) 265 { 266 struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; 267 u_int16_t msg; 268 __be16 cid = 0, pcid = 0; 269 typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound; 270 271 msg = ntohs(ctlh->messageType); 272 pr_debug("inbound control message %s\n", pptp_msg_name[msg]); 273 274 switch (msg) { 275 case PPTP_START_SESSION_REPLY: 276 /* server confirms new control session */ 277 if (info->sstate < PPTP_SESSION_REQUESTED) 278 goto invalid; 279 if (pptpReq->srep.resultCode == PPTP_START_OK) 280 info->sstate = PPTP_SESSION_CONFIRMED; 281 else 282 info->sstate = PPTP_SESSION_ERROR; 283 break; 284 285 case PPTP_STOP_SESSION_REPLY: 286 /* server confirms end of control session */ 287 if (info->sstate > PPTP_SESSION_STOPREQ) 288 goto invalid; 289 if (pptpReq->strep.resultCode == PPTP_STOP_OK) 290 info->sstate = PPTP_SESSION_NONE; 291 else 292 info->sstate = PPTP_SESSION_ERROR; 293 break; 294 295 case PPTP_OUT_CALL_REPLY: 296 /* server accepted call, we now expect GRE frames */ 297 if (info->sstate != PPTP_SESSION_CONFIRMED) 298 goto invalid; 299 if (info->cstate != PPTP_CALL_OUT_REQ && 300 info->cstate != PPTP_CALL_OUT_CONF) 301 goto invalid; 302 303 cid = pptpReq->ocack.callID; 304 pcid = pptpReq->ocack.peersCallID; 305 if (info->pns_call_id != pcid) 306 goto invalid; 307 pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], 308 ntohs(cid), ntohs(pcid)); 309 310 if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) { 311 info->cstate = PPTP_CALL_OUT_CONF; 312 info->pac_call_id = cid; 313 exp_gre(ct, cid, pcid); 314 } else 315 info->cstate = PPTP_CALL_NONE; 316 break; 317 318 case PPTP_IN_CALL_REQUEST: 319 /* server tells us about incoming call request */ 320 if (info->sstate != PPTP_SESSION_CONFIRMED) 321 goto invalid; 322 323 cid = pptpReq->icreq.callID; 324 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); 325 info->cstate = PPTP_CALL_IN_REQ; 326 info->pac_call_id = cid; 327 break; 328 329 case PPTP_IN_CALL_CONNECT: 330 /* server tells us about incoming call established */ 331 if (info->sstate != PPTP_SESSION_CONFIRMED) 332 goto invalid; 333 if (info->cstate != PPTP_CALL_IN_REP && 334 info->cstate != PPTP_CALL_IN_CONF) 335 goto invalid; 336 337 pcid = pptpReq->iccon.peersCallID; 338 cid = info->pac_call_id; 339 340 if (info->pns_call_id != pcid) 341 goto invalid; 342 343 pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid)); 344 info->cstate = PPTP_CALL_IN_CONF; 345 346 /* we expect a GRE connection from PAC to PNS */ 347 exp_gre(ct, cid, pcid); 348 break; 349 350 case PPTP_CALL_DISCONNECT_NOTIFY: 351 /* server confirms disconnect */ 352 cid = pptpReq->disc.callID; 353 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); 354 info->cstate = PPTP_CALL_NONE; 355 356 /* untrack this call id, unexpect GRE packets */ 357 pptp_destroy_siblings(ct); 358 break; 359 360 case PPTP_WAN_ERROR_NOTIFY: 361 case PPTP_ECHO_REQUEST: 362 case PPTP_ECHO_REPLY: 363 /* I don't have to explain these ;) */ 364 break; 365 366 default: 367 goto invalid; 368 } 369 370 nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound); 371 if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK) 372 return nf_nat_pptp_inbound(skb, ct, ctinfo, ctlh, pptpReq); 373 return NF_ACCEPT; 374 375 invalid: 376 pr_debug("invalid %s: type=%d cid=%u pcid=%u " 377 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", 378 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], 379 msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, 380 ntohs(info->pns_call_id), ntohs(info->pac_call_id)); 381 return NF_ACCEPT; 382 } 383 384 static inline int 385 pptp_outbound_pkt(struct sk_buff *skb, 386 struct PptpControlHeader *ctlh, 387 union pptp_ctrl_union *pptpReq, 388 unsigned int reqlen, 389 struct nf_conn *ct, 390 enum ip_conntrack_info ctinfo) 391 { 392 struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; 393 u_int16_t msg; 394 __be16 cid = 0, pcid = 0; 395 typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound; 396 397 msg = ntohs(ctlh->messageType); 398 pr_debug("outbound control message %s\n", pptp_msg_name[msg]); 399 400 switch (msg) { 401 case PPTP_START_SESSION_REQUEST: 402 /* client requests for new control session */ 403 if (info->sstate != PPTP_SESSION_NONE) 404 goto invalid; 405 info->sstate = PPTP_SESSION_REQUESTED; 406 break; 407 408 case PPTP_STOP_SESSION_REQUEST: 409 /* client requests end of control session */ 410 info->sstate = PPTP_SESSION_STOPREQ; 411 break; 412 413 case PPTP_OUT_CALL_REQUEST: 414 /* client initiating connection to server */ 415 if (info->sstate != PPTP_SESSION_CONFIRMED) 416 goto invalid; 417 info->cstate = PPTP_CALL_OUT_REQ; 418 /* track PNS call id */ 419 cid = pptpReq->ocreq.callID; 420 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); 421 info->pns_call_id = cid; 422 break; 423 424 case PPTP_IN_CALL_REPLY: 425 /* client answers incoming call */ 426 if (info->cstate != PPTP_CALL_IN_REQ && 427 info->cstate != PPTP_CALL_IN_REP) 428 goto invalid; 429 430 cid = pptpReq->icack.callID; 431 pcid = pptpReq->icack.peersCallID; 432 if (info->pac_call_id != pcid) 433 goto invalid; 434 pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg], 435 ntohs(cid), ntohs(pcid)); 436 437 if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) { 438 /* part two of the three-way handshake */ 439 info->cstate = PPTP_CALL_IN_REP; 440 info->pns_call_id = cid; 441 } else 442 info->cstate = PPTP_CALL_NONE; 443 break; 444 445 case PPTP_CALL_CLEAR_REQUEST: 446 /* client requests hangup of call */ 447 if (info->sstate != PPTP_SESSION_CONFIRMED) 448 goto invalid; 449 /* FUTURE: iterate over all calls and check if 450 * call ID is valid. We don't do this without newnat, 451 * because we only know about last call */ 452 info->cstate = PPTP_CALL_CLEAR_REQ; 453 break; 454 455 case PPTP_SET_LINK_INFO: 456 case PPTP_ECHO_REQUEST: 457 case PPTP_ECHO_REPLY: 458 /* I don't have to explain these ;) */ 459 break; 460 461 default: 462 goto invalid; 463 } 464 465 nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound); 466 if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK) 467 return nf_nat_pptp_outbound(skb, ct, ctinfo, ctlh, pptpReq); 468 return NF_ACCEPT; 469 470 invalid: 471 pr_debug("invalid %s: type=%d cid=%u pcid=%u " 472 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n", 473 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], 474 msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, 475 ntohs(info->pns_call_id), ntohs(info->pac_call_id)); 476 return NF_ACCEPT; 477 } 478 479 static const unsigned int pptp_msg_size[] = { 480 [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest), 481 [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply), 482 [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest), 483 [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply), 484 [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest), 485 [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply), 486 [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest), 487 [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply), 488 [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected), 489 [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest), 490 [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify), 491 [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify), 492 [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo), 493 }; 494 495 /* track caller id inside control connection, call expect_related */ 496 static int 497 conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff, 498 struct nf_conn *ct, enum ip_conntrack_info ctinfo) 499 500 { 501 int dir = CTINFO2DIR(ctinfo); 502 const struct nf_ct_pptp_master *info = &nfct_help(ct)->help.ct_pptp_info; 503 const struct tcphdr *tcph; 504 struct tcphdr _tcph; 505 const struct pptp_pkt_hdr *pptph; 506 struct pptp_pkt_hdr _pptph; 507 struct PptpControlHeader _ctlh, *ctlh; 508 union pptp_ctrl_union _pptpReq, *pptpReq; 509 unsigned int tcplen = skb->len - protoff; 510 unsigned int datalen, reqlen, nexthdr_off; 511 int oldsstate, oldcstate; 512 int ret; 513 u_int16_t msg; 514 515 /* don't do any tracking before tcp handshake complete */ 516 if (ctinfo != IP_CT_ESTABLISHED && 517 ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) 518 return NF_ACCEPT; 519 520 nexthdr_off = protoff; 521 tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph); 522 BUG_ON(!tcph); 523 nexthdr_off += tcph->doff * 4; 524 datalen = tcplen - tcph->doff * 4; 525 526 pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph); 527 if (!pptph) { 528 pr_debug("no full PPTP header, can't track\n"); 529 return NF_ACCEPT; 530 } 531 nexthdr_off += sizeof(_pptph); 532 datalen -= sizeof(_pptph); 533 534 /* if it's not a control message we can't do anything with it */ 535 if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL || 536 ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) { 537 pr_debug("not a control packet\n"); 538 return NF_ACCEPT; 539 } 540 541 ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh); 542 if (!ctlh) 543 return NF_ACCEPT; 544 nexthdr_off += sizeof(_ctlh); 545 datalen -= sizeof(_ctlh); 546 547 reqlen = datalen; 548 msg = ntohs(ctlh->messageType); 549 if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg]) 550 return NF_ACCEPT; 551 if (reqlen > sizeof(*pptpReq)) 552 reqlen = sizeof(*pptpReq); 553 554 pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq); 555 if (!pptpReq) 556 return NF_ACCEPT; 557 558 oldsstate = info->sstate; 559 oldcstate = info->cstate; 560 561 spin_lock_bh(&nf_pptp_lock); 562 563 /* FIXME: We just blindly assume that the control connection is always 564 * established from PNS->PAC. However, RFC makes no guarantee */ 565 if (dir == IP_CT_DIR_ORIGINAL) 566 /* client -> server (PNS -> PAC) */ 567 ret = pptp_outbound_pkt(skb, ctlh, pptpReq, reqlen, ct, 568 ctinfo); 569 else 570 /* server -> client (PAC -> PNS) */ 571 ret = pptp_inbound_pkt(skb, ctlh, pptpReq, reqlen, ct, 572 ctinfo); 573 pr_debug("sstate: %d->%d, cstate: %d->%d\n", 574 oldsstate, info->sstate, oldcstate, info->cstate); 575 spin_unlock_bh(&nf_pptp_lock); 576 577 return ret; 578 } 579 580 static const struct nf_conntrack_expect_policy pptp_exp_policy = { 581 .max_expected = 2, 582 .timeout = 5 * 60, 583 }; 584 585 /* control protocol helper */ 586 static struct nf_conntrack_helper pptp __read_mostly = { 587 .name = "pptp", 588 .me = THIS_MODULE, 589 .tuple.src.l3num = AF_INET, 590 .tuple.src.u.tcp.port = __constant_htons(PPTP_CONTROL_PORT), 591 .tuple.dst.protonum = IPPROTO_TCP, 592 .help = conntrack_pptp_help, 593 .destroy = pptp_destroy_siblings, 594 .expect_policy = &pptp_exp_policy, 595 }; 596 597 static int __init nf_conntrack_pptp_init(void) 598 { 599 return nf_conntrack_helper_register(&pptp); 600 } 601 602 static void __exit nf_conntrack_pptp_fini(void) 603 { 604 nf_conntrack_helper_unregister(&pptp); 605 nf_ct_gre_keymap_flush(); 606 } 607 608 module_init(nf_conntrack_pptp_init); 609 module_exit(nf_conntrack_pptp_fini); 610