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