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 MODULE_ALIAS_NFCT_HELPER("pptp"); 41 42 static DEFINE_SPINLOCK(nf_pptp_lock); 43 44 int 45 (*nf_nat_pptp_hook_outbound)(struct sk_buff *skb, 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 52 (*nf_nat_pptp_hook_inbound)(struct sk_buff *skb, 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 69 #if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG) 70 /* PptpControlMessageType names */ 71 const char *const pptp_msg_name[] = { 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); 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 { 102 struct net *net = nf_ct_net(ct); 103 typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn; 104 pr_debug("increasing timeouts\n"); 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); 115 if (nf_nat_pptp_expectfn && ct->master->status & IPS_NAT_MASK) 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); 123 pr_debug("trying to unexpect other dir: "); 124 nf_ct_dump_tuple(&inv_t); 125 126 exp_other = nf_ct_expect_find_get(net, &inv_t); 127 if (exp_other) { 128 /* delete other expectation. */ 129 pr_debug("found\n"); 130 nf_ct_unexpect_related(exp_other); 131 nf_ct_expect_put(exp_other); 132 } else { 133 pr_debug("not found\n"); 134 } 135 } 136 rcu_read_unlock(); 137 } 138 139 static int destroy_sibling_or_exp(struct net *net, 140 const struct nf_conntrack_tuple *t) 141 { 142 const struct nf_conntrack_tuple_hash *h; 143 struct nf_conntrack_expect *exp; 144 struct nf_conn *sibling; 145 146 pr_debug("trying to timeout ct or exp for tuple "); 147 nf_ct_dump_tuple(t); 148 149 h = nf_conntrack_find_get(net, t); 150 if (h) { 151 sibling = nf_ct_tuplehash_to_ctrack(h); 152 pr_debug("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(net, t); 161 if (exp) { 162 pr_debug("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 net *net = nf_ct_net(ct); 175 const struct nf_conn_help *help = nfct_help(ct); 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; 185 if (!destroy_sibling_or_exp(net, &t)) 186 pr_debug("failed to timeout original pns->pac ct/exp\n"); 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; 193 if (!destroy_sibling_or_exp(net, &t)) 194 pr_debug("failed to timeout reply pac->pns ct/exp\n"); 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; 204 205 exp_orig = nf_ct_expect_alloc(ct); 206 if (exp_orig == NULL) 207 goto out; 208 209 exp_reply = nf_ct_expect_alloc(ct); 210 if (exp_reply == NULL) 211 goto out_put_orig; 212 213 /* original direction, PNS->PAC */ 214 dir = IP_CT_DIR_ORIGINAL; 215 nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT, 216 nf_ct_l3num(ct), 217 &ct->tuplehash[dir].tuple.src.u3, 218 &ct->tuplehash[dir].tuple.dst.u3, 219 IPPROTO_GRE, &peer_callid, &callid); 220 exp_orig->expectfn = pptp_expectfn; 221 222 /* reply direction, PAC->PNS */ 223 dir = IP_CT_DIR_REPLY; 224 nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT, 225 nf_ct_l3num(ct), 226 &ct->tuplehash[dir].tuple.src.u3, 227 &ct->tuplehash[dir].tuple.dst.u3, 228 IPPROTO_GRE, &callid, &peer_callid); 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); 234 if (nf_ct_expect_related(exp_orig) != 0) 235 goto out_put_both; 236 if (nf_ct_expect_related(exp_reply) != 0) 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: 249 nf_ct_expect_put(exp_reply); 250 out_put_orig: 251 nf_ct_expect_put(exp_orig); 252 out: 253 return ret; 254 255 out_unexpect_both: 256 nf_ct_unexpect_related(exp_reply); 257 out_unexpect_orig: 258 nf_ct_unexpect_related(exp_orig); 259 goto out_put_both; 260 } 261 262 static inline int 263 pptp_inbound_pkt(struct sk_buff *skb, 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); 276 pr_debug("inbound control message %s\n", pptp_msg_name[msg]); 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; 311 pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], 312 ntohs(cid), ntohs(pcid)); 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; 328 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); 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; 346 347 pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid)); 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; 357 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); 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) 376 return nf_nat_pptp_inbound(skb, ct, ctinfo, ctlh, pptpReq); 377 return NF_ACCEPT; 378 379 invalid: 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)); 385 return NF_ACCEPT; 386 } 387 388 static inline int 389 pptp_outbound_pkt(struct sk_buff *skb, 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); 402 pr_debug("outbound control message %s\n", pptp_msg_name[msg]); 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; 424 pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid)); 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; 438 pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg], 439 ntohs(cid), ntohs(pcid)); 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) 471 return nf_nat_pptp_outbound(skb, ct, ctinfo, ctlh, pptpReq); 472 return NF_ACCEPT; 473 474 invalid: 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)); 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 501 conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff, 502 struct nf_conn *ct, enum ip_conntrack_info ctinfo) 503 504 { 505 int dir = CTINFO2DIR(ctinfo); 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; 511 struct PptpControlHeader _ctlh, *ctlh; 512 union pptp_ctrl_union _pptpReq, *pptpReq; 513 unsigned int tcplen = skb->len - protoff; 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; 525 tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph); 526 BUG_ON(!tcph); 527 nexthdr_off += tcph->doff * 4; 528 datalen = tcplen - tcph->doff * 4; 529 530 pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph); 531 if (!pptph) { 532 pr_debug("no full PPTP header, can't track\n"); 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) { 541 pr_debug("not a control packet\n"); 542 return NF_ACCEPT; 543 } 544 545 ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh); 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); 557 558 pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq); 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) */ 571 ret = pptp_outbound_pkt(skb, ctlh, pptpReq, reqlen, ct, 572 ctinfo); 573 else 574 /* server -> client (PAC -> PNS) */ 575 ret = pptp_inbound_pkt(skb, ctlh, pptpReq, reqlen, ct, 576 ctinfo); 577 pr_debug("sstate: %d->%d, cstate: %d->%d\n", 578 oldsstate, info->sstate, oldcstate, info->cstate); 579 spin_unlock_bh(&nf_pptp_lock); 580 581 return ret; 582 } 583 584 static const struct nf_conntrack_expect_policy pptp_exp_policy = { 585 .max_expected = 2, 586 .timeout = 5 * 60, 587 }; 588 589 /* control protocol helper */ 590 static struct nf_conntrack_helper pptp __read_mostly = { 591 .name = "pptp", 592 .me = THIS_MODULE, 593 .tuple.src.l3num = AF_INET, 594 .tuple.src.u.tcp.port = __constant_htons(PPTP_CONTROL_PORT), 595 .tuple.dst.protonum = IPPROTO_TCP, 596 .help = conntrack_pptp_help, 597 .destroy = pptp_destroy_siblings, 598 .expect_policy = &pptp_exp_policy, 599 }; 600 601 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 }; 609 610 static int __init nf_conntrack_pptp_init(void) 611 { 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; 621 } 622 623 static void __exit nf_conntrack_pptp_fini(void) 624 { 625 nf_conntrack_helper_unregister(&pptp); 626 unregister_pernet_subsys(&nf_conntrack_pptp_net_ops); 627 } 628 629 module_init(nf_conntrack_pptp_init); 630 module_exit(nf_conntrack_pptp_fini); 631