err.no Git - linux-2.6/blob - net/ipv4/netfilter/ip_conntrack_helper_pptp.c

   1 /*
   2  * ip_conntrack_pptp.c  - Version 3.0
   3  *
   4  * Connection tracking support for PPTP (Point to Point Tunneling Protocol).
   5  * PPTP is a a protocol for creating virtual private networks.
   6  * It is a specification defined by Microsoft and some vendors
   7  * working with Microsoft.  PPTP is built on top of a modified
   8  * version of the Internet Generic Routing Encapsulation Protocol.
   9  * GRE is defined in RFC 1701 and RFC 1702.  Documentation of
  10  * PPTP can be found in RFC 2637
  11  *
  12  * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
  13  *
  14  * Development of this code funded by Astaro AG (http://www.astaro.com/)
  15  *
  16  * Limitations:
  17  *       - We blindly assume that control connections are always
  18  *         established in PNS->PAC direction.  This is a violation
  19  *         of RFFC2673
  20  *       - We can only support one single call within each session
  21  *
  22  * TODO:
  23  *       - testing of incoming PPTP calls
  24  *
  25  * Changes:
  26  *      2002-02-05 - Version 1.3
  27  *        - Call ip_conntrack_unexpect_related() from
  28  *          pptp_destroy_siblings() to destroy expectations in case
  29  *          CALL_DISCONNECT_NOTIFY or tcp fin packet was seen
  30  *          (Philip Craig <philipc@snapgear.com>)
  31  *        - Add Version information at module loadtime
  32  *      2002-02-10 - Version 1.6
  33  *        - move to C99 style initializers
  34  *        - remove second expectation if first arrives
  35  *      2004-10-22 - Version 2.0
  36  *        - merge Mandrake's 2.6.x port with recent 2.6.x API changes
  37  *        - fix lots of linear skb assumptions from Mandrake's port
  38  *      2005-06-10 - Version 2.1
  39  *        - use ip_conntrack_expect_free() instead of kfree() on the
  40  *          expect's (which are from the slab for quite some time)
  41  *      2005-06-10 - Version 3.0
  42  *        - port helper to post-2.6.11 API changes,
  43  *          funded by Oxcoda NetBox Blue (http://www.netboxblue.com/)
  44  *      2005-07-30 - Version 3.1
  45  *        - port helper to 2.6.13 API changes
  46  *
  47  */
  48
  49 #include <linux/module.h>
  50 #include <linux/netfilter.h>
  51 #include <linux/ip.h>
  52 #include <net/checksum.h>
  53 #include <net/tcp.h>
  54
  55 #include <linux/netfilter_ipv4/ip_conntrack.h>
  56 #include <linux/netfilter_ipv4/ip_conntrack_core.h>
  57 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
  58 #include <linux/netfilter_ipv4/ip_conntrack_proto_gre.h>
  59 #include <linux/netfilter_ipv4/ip_conntrack_pptp.h>
  60
  61 #define IP_CT_PPTP_VERSION "3.1"
  62
  63 MODULE_LICENSE("GPL");
  64 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
  65 MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP");
  66
  67 static DEFINE_SPINLOCK(ip_pptp_lock);
  68
  69 int
  70 (*ip_nat_pptp_hook_outbound)(struct sk_buff **pskb,
  71                           struct ip_conntrack *ct,
  72                           enum ip_conntrack_info ctinfo,
  73                           struct PptpControlHeader *ctlh,
  74                           union pptp_ctrl_union *pptpReq);
  75
  76 int
  77 (*ip_nat_pptp_hook_inbound)(struct sk_buff **pskb,
  78                           struct ip_conntrack *ct,
  79                           enum ip_conntrack_info ctinfo,
  80                           struct PptpControlHeader *ctlh,
  81                           union pptp_ctrl_union *pptpReq);
  82
  83 void
  84 (*ip_nat_pptp_hook_exp_gre)(struct ip_conntrack_expect *expect_orig,
  85                             struct ip_conntrack_expect *expect_reply);
  86
  87 void
  88 (*ip_nat_pptp_hook_expectfn)(struct ip_conntrack *ct,
  89                              struct ip_conntrack_expect *exp);
  90
  91 #if 0
  92 /* PptpControlMessageType names */
  93 const char *pptp_msg_name[] = {
  94         "UNKNOWN_MESSAGE",
  95         "START_SESSION_REQUEST",
  96         "START_SESSION_REPLY",
  97         "STOP_SESSION_REQUEST",
  98         "STOP_SESSION_REPLY",
  99         "ECHO_REQUEST",
 100         "ECHO_REPLY",
 101         "OUT_CALL_REQUEST",
 102         "OUT_CALL_REPLY",
 103         "IN_CALL_REQUEST",
 104         "IN_CALL_REPLY",
 105         "IN_CALL_CONNECT",
 106         "CALL_CLEAR_REQUEST",
 107         "CALL_DISCONNECT_NOTIFY",
 108         "WAN_ERROR_NOTIFY",
 109         "SET_LINK_INFO"
 110 };
 111 EXPORT_SYMBOL(pptp_msg_name);
 112 #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, __FUNCTION__, ## args)
 113 #else
 114 #define DEBUGP(format, args...)
 115 #endif
 116
 117 #define SECS *HZ
 118 #define MINS * 60 SECS
 119 #define HOURS * 60 MINS
 120
 121 #define PPTP_GRE_TIMEOUT                (10 MINS)
 122 #define PPTP_GRE_STREAM_TIMEOUT         (5 HOURS)
 123
 124 static void pptp_expectfn(struct ip_conntrack *ct,
 125                          struct ip_conntrack_expect *exp)
 126 {
 127         DEBUGP("increasing timeouts\n");
 128
 129         /* increase timeout of GRE data channel conntrack entry */
 130         ct->proto.gre.timeout = PPTP_GRE_TIMEOUT;
 131         ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT;
 132
 133         /* Can you see how rusty this code is, compared with the pre-2.6.11
 134          * one? That's what happened to my shiny newnat of 2002 ;( -HW */
 135
 136         if (!ip_nat_pptp_hook_expectfn) {
 137                 struct ip_conntrack_tuple inv_t;
 138                 struct ip_conntrack_expect *exp_other;
 139
 140                 /* obviously this tuple inversion only works until you do NAT */
 141                 invert_tuplepr(&inv_t, &exp->tuple);
 142                 DEBUGP("trying to unexpect other dir: ");
 143                 DUMP_TUPLE(&inv_t);
 144
 145                 exp_other = ip_conntrack_expect_find(&inv_t);
 146                 if (exp_other) {
 147                         /* delete other expectation.  */
 148                         DEBUGP("found\n");
 149                         ip_conntrack_unexpect_related(exp_other);
 150                         ip_conntrack_expect_put(exp_other);
 151                 } else {
 152                         DEBUGP("not found\n");
 153                 }
 154         } else {
 155                 /* we need more than simple inversion */
 156                 ip_nat_pptp_hook_expectfn(ct, exp);
 157         }
 158 }
 159
 160 static int destroy_sibling_or_exp(const struct ip_conntrack_tuple *t)
 161 {
 162         struct ip_conntrack_tuple_hash *h;
 163         struct ip_conntrack_expect *exp;
 164
 165         DEBUGP("trying to timeout ct or exp for tuple ");
 166         DUMP_TUPLE(t);
 167
 168         h = ip_conntrack_find_get(t, NULL);
 169         if (h)  {
 170                 struct ip_conntrack *sibling = tuplehash_to_ctrack(h);
 171                 DEBUGP("setting timeout of conntrack %p to 0\n", sibling);
 172                 sibling->proto.gre.timeout = 0;
 173                 sibling->proto.gre.stream_timeout = 0;
 174                 if (del_timer(&sibling->timeout))
 175                         sibling->timeout.function((unsigned long)sibling);
 176                 ip_conntrack_put(sibling);
 177                 return 1;
 178         } else {
 179                 exp = ip_conntrack_expect_find(t);
 180                 if (exp) {
 181                         DEBUGP("unexpect_related of expect %p\n", exp);
 182                         ip_conntrack_unexpect_related(exp);
 183                         ip_conntrack_expect_put(exp);
 184                         return 1;
 185                 }
 186         }
 187
 188         return 0;
 189 }
 190
 191
 192 /* timeout GRE data connections */
 193 static void pptp_destroy_siblings(struct ip_conntrack *ct)
 194 {
 195         struct ip_conntrack_tuple t;
 196
 197         /* Since ct->sibling_list has literally rusted away in 2.6.11,
 198          * we now need another way to find out about our sibling
 199          * contrack and expects... -HW */
 200
 201         /* try original (pns->pac) tuple */
 202         memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t));
 203         t.dst.protonum = IPPROTO_GRE;
 204         t.src.u.gre.key = ct->help.ct_pptp_info.pns_call_id;
 205         t.dst.u.gre.key = ct->help.ct_pptp_info.pac_call_id;
 206
 207         if (!destroy_sibling_or_exp(&t))
 208                 DEBUGP("failed to timeout original pns->pac ct/exp\n");
 209
 210         /* try reply (pac->pns) tuple */
 211         memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t));
 212         t.dst.protonum = IPPROTO_GRE;
 213         t.src.u.gre.key = ct->help.ct_pptp_info.pac_call_id;
 214         t.dst.u.gre.key = ct->help.ct_pptp_info.pns_call_id;
 215
 216         if (!destroy_sibling_or_exp(&t))
 217                 DEBUGP("failed to timeout reply pac->pns ct/exp\n");
 218 }
 219
 220 /* expect GRE connections (PNS->PAC and PAC->PNS direction) */
 221 static inline int
 222 exp_gre(struct ip_conntrack *ct,
 223         __be16 callid,
 224         __be16 peer_callid)
 225 {
 226         struct ip_conntrack_expect *exp_orig, *exp_reply;
 227         int ret = 1;
 228
 229         exp_orig = ip_conntrack_expect_alloc(ct);
 230         if (exp_orig == NULL)
 231                 goto out;
 232
 233         exp_reply = ip_conntrack_expect_alloc(ct);
 234         if (exp_reply == NULL)
 235                 goto out_put_orig;
 236
 237         /* original direction, PNS->PAC */
 238         exp_orig->tuple.src.ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip;
 239         exp_orig->tuple.src.u.gre.key = peer_callid;
 240         exp_orig->tuple.dst.ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip;
 241         exp_orig->tuple.dst.u.gre.key = callid;
 242         exp_orig->tuple.dst.protonum = IPPROTO_GRE;
 243
 244         exp_orig->mask.src.ip = 0xffffffff;
 245         exp_orig->mask.src.u.all = 0;
 246         exp_orig->mask.dst.u.gre.key = htons(0xffff);
 247         exp_orig->mask.dst.ip = 0xffffffff;
 248         exp_orig->mask.dst.protonum = 0xff;
 249
 250         exp_orig->master = ct;
 251         exp_orig->expectfn = pptp_expectfn;
 252         exp_orig->flags = 0;
 253
 254         /* both expectations are identical apart from tuple */
 255         memcpy(exp_reply, exp_orig, sizeof(*exp_reply));
 256
 257         /* reply direction, PAC->PNS */
 258         exp_reply->tuple.src.ip = ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip;
 259         exp_reply->tuple.src.u.gre.key = callid;
 260         exp_reply->tuple.dst.ip = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip;
 261         exp_reply->tuple.dst.u.gre.key = peer_callid;
 262         exp_reply->tuple.dst.protonum = IPPROTO_GRE;
 263
 264         if (ip_nat_pptp_hook_exp_gre)
 265                 ip_nat_pptp_hook_exp_gre(exp_orig, exp_reply);
 266         if (ip_conntrack_expect_related(exp_orig) != 0)
 267                 goto out_put_both;
 268         if (ip_conntrack_expect_related(exp_reply) != 0)
 269                 goto out_unexpect_orig;
 270
 271         /* Add GRE keymap entries */
 272         if (ip_ct_gre_keymap_add(ct, &exp_orig->tuple, 0) != 0)
 273                 goto out_unexpect_both;
 274         if (ip_ct_gre_keymap_add(ct, &exp_reply->tuple, 1) != 0) {
 275                 ip_ct_gre_keymap_destroy(ct);
 276                 goto out_unexpect_both;
 277         }
 278         ret = 0;
 279
 280 out_put_both:
 281         ip_conntrack_expect_put(exp_reply);
 282 out_put_orig:
 283         ip_conntrack_expect_put(exp_orig);
 284 out:
 285         return ret;
 286
 287 out_unexpect_both:
 288         ip_conntrack_unexpect_related(exp_reply);
 289 out_unexpect_orig:
 290         ip_conntrack_unexpect_related(exp_orig);
 291         goto out_put_both;
 292 }
 293
 294 static inline int
 295 pptp_inbound_pkt(struct sk_buff **pskb,
 296                  struct tcphdr *tcph,
 297                  unsigned int nexthdr_off,
 298                  unsigned int datalen,
 299                  struct ip_conntrack *ct,
 300                  enum ip_conntrack_info ctinfo)
 301 {
 302         struct PptpControlHeader _ctlh, *ctlh;
 303         unsigned int reqlen;
 304         union pptp_ctrl_union _pptpReq, *pptpReq;
 305         struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
 306         u_int16_t msg;
 307         __be16 cid, pcid;
 308
 309         ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh);
 310         if (!ctlh) {
 311                 DEBUGP("error during skb_header_pointer\n");
 312                 return NF_ACCEPT;
 313         }
 314         nexthdr_off += sizeof(_ctlh);
 315         datalen -= sizeof(_ctlh);
 316
 317         reqlen = datalen;
 318         if (reqlen > sizeof(*pptpReq))
 319                 reqlen = sizeof(*pptpReq);
 320         pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq);
 321         if (!pptpReq) {
 322                 DEBUGP("error during skb_header_pointer\n");
 323                 return NF_ACCEPT;
 324         }
 325
 326         msg = ntohs(ctlh->messageType);
 327         DEBUGP("inbound control message %s\n", pptp_msg_name[msg]);
 328
 329         switch (msg) {
 330         case PPTP_START_SESSION_REPLY:
 331                 if (reqlen < sizeof(_pptpReq.srep)) {
 332                         DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
 333                         break;
 334                 }
 335
 336                 /* server confirms new control session */
 337                 if (info->sstate < PPTP_SESSION_REQUESTED) {
 338                         DEBUGP("%s without START_SESS_REQUEST\n",
 339                                 pptp_msg_name[msg]);
 340                         break;
 341                 }
 342                 if (pptpReq->srep.resultCode == PPTP_START_OK)
 343                         info->sstate = PPTP_SESSION_CONFIRMED;
 344                 else
 345                         info->sstate = PPTP_SESSION_ERROR;
 346                 break;
 347
 348         case PPTP_STOP_SESSION_REPLY:
 349                 if (reqlen < sizeof(_pptpReq.strep)) {
 350                         DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
 351                         break;
 352                 }
 353
 354                 /* server confirms end of control session */
 355                 if (info->sstate > PPTP_SESSION_STOPREQ) {
 356                         DEBUGP("%s without STOP_SESS_REQUEST\n",
 357                                 pptp_msg_name[msg]);
 358                         break;
 359                 }
 360                 if (pptpReq->strep.resultCode == PPTP_STOP_OK)
 361                         info->sstate = PPTP_SESSION_NONE;
 362                 else
 363                         info->sstate = PPTP_SESSION_ERROR;
 364                 break;
 365
 366         case PPTP_OUT_CALL_REPLY:
 367                 if (reqlen < sizeof(_pptpReq.ocack)) {
 368                         DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
 369                         break;
 370                 }
 371
 372                 /* server accepted call, we now expect GRE frames */
 373                 if (info->sstate != PPTP_SESSION_CONFIRMED) {
 374                         DEBUGP("%s but no session\n", pptp_msg_name[msg]);
 375                         break;
 376                 }
 377                 if (info->cstate != PPTP_CALL_OUT_REQ &&
 378                     info->cstate != PPTP_CALL_OUT_CONF) {
 379                         DEBUGP("%s without OUTCALL_REQ\n", pptp_msg_name[msg]);
 380                         break;
 381                 }
 382                 if (pptpReq->ocack.resultCode != PPTP_OUTCALL_CONNECT) {
 383                         info->cstate = PPTP_CALL_NONE;
 384                         break;
 385                 }
 386
 387                 cid = pptpReq->ocack.callID;
 388                 pcid = pptpReq->ocack.peersCallID;
 389
 390                 info->pac_call_id = cid;
 391
 392                 if (info->pns_call_id != pcid) {
 393                         DEBUGP("%s for unknown callid %u\n",
 394                                 pptp_msg_name[msg], ntohs(pcid));
 395                         break;
 396                 }
 397
 398                 DEBUGP("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg],
 399                         ntohs(cid), ntohs(pcid));
 400
 401                 info->cstate = PPTP_CALL_OUT_CONF;
 402
 403                 exp_gre(ct, cid, pcid);
 404                 break;
 405
 406         case PPTP_IN_CALL_REQUEST:
 407                 if (reqlen < sizeof(_pptpReq.icack)) {
 408                         DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
 409                         break;
 410                 }
 411
 412                 /* server tells us about incoming call request */
 413                 if (info->sstate != PPTP_SESSION_CONFIRMED) {
 414                         DEBUGP("%s but no session\n", pptp_msg_name[msg]);
 415                         break;
 416                 }
 417                 pcid = pptpReq->icack.peersCallID;
 418                 DEBUGP("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid));
 419                 info->cstate = PPTP_CALL_IN_REQ;
 420                 info->pac_call_id = pcid;
 421                 break;
 422
 423         case PPTP_IN_CALL_CONNECT:
 424                 if (reqlen < sizeof(_pptpReq.iccon)) {
 425                         DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
 426                         break;
 427                 }
 428
 429                 /* server tells us about incoming call established */
 430                 if (info->sstate != PPTP_SESSION_CONFIRMED) {
 431                         DEBUGP("%s but no session\n", pptp_msg_name[msg]);
 432                         break;
 433                 }
 434                 if (info->cstate != PPTP_CALL_IN_REP
 435                     && info->cstate != PPTP_CALL_IN_CONF) {
 436                         DEBUGP("%s but never sent IN_CALL_REPLY\n",
 437                                 pptp_msg_name[msg]);
 438                         break;
 439                 }
 440
 441                 pcid = pptpReq->iccon.peersCallID;
 442                 cid = info->pac_call_id;
 443
 444                 if (info->pns_call_id != pcid) {
 445                         DEBUGP("%s for unknown CallID %u\n",
 446                                 pptp_msg_name[msg], ntohs(pcid));
 447                         break;
 448                 }
 449
 450                 DEBUGP("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid));
 451                 info->cstate = PPTP_CALL_IN_CONF;
 452
 453                 /* we expect a GRE connection from PAC to PNS */
 454                 exp_gre(ct, cid, pcid);
 455                 break;
 456
 457         case PPTP_CALL_DISCONNECT_NOTIFY:
 458                 if (reqlen < sizeof(_pptpReq.disc)) {
 459                         DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
 460                         break;
 461                 }
 462
 463                 /* server confirms disconnect */
 464                 cid = pptpReq->disc.callID;
 465                 DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
 466                 info->cstate = PPTP_CALL_NONE;
 467
 468                 /* untrack this call id, unexpect GRE packets */
 469                 pptp_destroy_siblings(ct);
 470                 break;
 471
 472         case PPTP_WAN_ERROR_NOTIFY:
 473                 break;
 474
 475         case PPTP_ECHO_REQUEST:
 476         case PPTP_ECHO_REPLY:
 477                 /* I don't have to explain these ;) */
 478                 break;
 479         default:
 480                 DEBUGP("invalid %s (TY=%d)\n", (msg <= PPTP_MSG_MAX)
 481                         ? pptp_msg_name[msg]:pptp_msg_name[0], msg);
 482                 break;
 483         }
 484
 485
 486         if (ip_nat_pptp_hook_inbound)
 487                 return ip_nat_pptp_hook_inbound(pskb, ct, ctinfo, ctlh,
 488                                                 pptpReq);
 489
 490         return NF_ACCEPT;
 491
 492 }
 493
 494 static inline int
 495 pptp_outbound_pkt(struct sk_buff **pskb,
 496                   struct tcphdr *tcph,
 497                   unsigned int nexthdr_off,
 498                   unsigned int datalen,
 499                   struct ip_conntrack *ct,
 500                   enum ip_conntrack_info ctinfo)
 501 {
 502         struct PptpControlHeader _ctlh, *ctlh;
 503         unsigned int reqlen;
 504         union pptp_ctrl_union _pptpReq, *pptpReq;
 505         struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
 506         u_int16_t msg;
 507         __be16 cid, pcid;
 508
 509         ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh);
 510         if (!ctlh)
 511                 return NF_ACCEPT;
 512         nexthdr_off += sizeof(_ctlh);
 513         datalen -= sizeof(_ctlh);
 514
 515         reqlen = datalen;
 516         if (reqlen > sizeof(*pptpReq))
 517                 reqlen = sizeof(*pptpReq);
 518         pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq);
 519         if (!pptpReq)
 520                 return NF_ACCEPT;
 521
 522         msg = ntohs(ctlh->messageType);
 523         DEBUGP("outbound control message %s\n", pptp_msg_name[msg]);
 524
 525         switch (msg) {
 526         case PPTP_START_SESSION_REQUEST:
 527                 /* client requests for new control session */
 528                 if (info->sstate != PPTP_SESSION_NONE) {
 529                         DEBUGP("%s but we already have one",
 530                                 pptp_msg_name[msg]);
 531                 }
 532                 info->sstate = PPTP_SESSION_REQUESTED;
 533                 break;
 534         case PPTP_STOP_SESSION_REQUEST:
 535                 /* client requests end of control session */
 536                 info->sstate = PPTP_SESSION_STOPREQ;
 537                 break;
 538
 539         case PPTP_OUT_CALL_REQUEST:
 540                 if (reqlen < sizeof(_pptpReq.ocreq)) {
 541                         DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
 542                         break;
 543                 }
 544
 545                 /* client initiating connection to server */
 546                 if (info->sstate != PPTP_SESSION_CONFIRMED) {
 547                         DEBUGP("%s but no session\n",
 548                                 pptp_msg_name[msg]);
 549                         break;
 550                 }
 551                 info->cstate = PPTP_CALL_OUT_REQ;
 552                 /* track PNS call id */
 553                 cid = pptpReq->ocreq.callID;
 554                 DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
 555                 info->pns_call_id = cid;
 556                 break;
 557         case PPTP_IN_CALL_REPLY:
 558                 if (reqlen < sizeof(_pptpReq.icack)) {
 559                         DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
 560                         break;
 561                 }
 562
 563                 /* client answers incoming call */
 564                 if (info->cstate != PPTP_CALL_IN_REQ
 565                     && info->cstate != PPTP_CALL_IN_REP) {
 566                         DEBUGP("%s without incall_req\n",
 567                                 pptp_msg_name[msg]);
 568                         break;
 569                 }
 570                 if (pptpReq->icack.resultCode != PPTP_INCALL_ACCEPT) {
 571                         info->cstate = PPTP_CALL_NONE;
 572                         break;
 573                 }
 574                 pcid = pptpReq->icack.peersCallID;
 575                 if (info->pac_call_id != pcid) {
 576                         DEBUGP("%s for unknown call %u\n",
 577                                 pptp_msg_name[msg], ntohs(pcid));
 578                         break;
 579                 }
 580                 DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(pcid));
 581                 /* part two of the three-way handshake */
 582                 info->cstate = PPTP_CALL_IN_REP;
 583                 info->pns_call_id = pcid;
 584                 break;
 585
 586         case PPTP_CALL_CLEAR_REQUEST:
 587                 /* client requests hangup of call */
 588                 if (info->sstate != PPTP_SESSION_CONFIRMED) {
 589                         DEBUGP("CLEAR_CALL but no session\n");
 590                         break;
 591                 }
 592                 /* FUTURE: iterate over all calls and check if
 593                  * call ID is valid.  We don't do this without newnat,
 594                  * because we only know about last call */
 595                 info->cstate = PPTP_CALL_CLEAR_REQ;
 596                 break;
 597         case PPTP_SET_LINK_INFO:
 598                 break;
 599         case PPTP_ECHO_REQUEST:
 600         case PPTP_ECHO_REPLY:
 601                 /* I don't have to explain these ;) */
 602                 break;
 603         default:
 604                 DEBUGP("invalid %s (TY=%d)\n", (msg <= PPTP_MSG_MAX)?
 605                         pptp_msg_name[msg]:pptp_msg_name[0], msg);
 606                 /* unknown: no need to create GRE masq table entry */
 607                 break;
 608         }
 609
 610         if (ip_nat_pptp_hook_outbound)
 611                 return ip_nat_pptp_hook_outbound(pskb, ct, ctinfo, ctlh,
 612                                                  pptpReq);
 613
 614         return NF_ACCEPT;
 615 }
 616
 617
 618 /* track caller id inside control connection, call expect_related */
 619 static int
 620 conntrack_pptp_help(struct sk_buff **pskb,
 621                     struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
 622
 623 {
 624         struct pptp_pkt_hdr _pptph, *pptph;
 625         struct tcphdr _tcph, *tcph;
 626         u_int32_t tcplen = (*pskb)->len - (*pskb)->nh.iph->ihl * 4;
 627         u_int32_t datalen;
 628         int dir = CTINFO2DIR(ctinfo);
 629         struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
 630         unsigned int nexthdr_off;
 631
 632         int oldsstate, oldcstate;
 633         int ret;
 634
 635         /* don't do any tracking before tcp handshake complete */
 636         if (ctinfo != IP_CT_ESTABLISHED
 637             && ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) {
 638                 DEBUGP("ctinfo = %u, skipping\n", ctinfo);
 639                 return NF_ACCEPT;
 640         }
 641
 642         nexthdr_off = (*pskb)->nh.iph->ihl*4;
 643         tcph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_tcph), &_tcph);
 644         BUG_ON(!tcph);
 645         nexthdr_off += tcph->doff * 4;
 646         datalen = tcplen - tcph->doff * 4;
 647
 648         if (tcph->fin || tcph->rst) {
 649                 DEBUGP("RST/FIN received, timeouting GRE\n");
 650                 /* can't do this after real newnat */
 651                 info->cstate = PPTP_CALL_NONE;
 652
 653                 /* untrack this call id, unexpect GRE packets */
 654                 pptp_destroy_siblings(ct);
 655         }
 656
 657         pptph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_pptph), &_pptph);
 658         if (!pptph) {
 659                 DEBUGP("no full PPTP header, can't track\n");
 660                 return NF_ACCEPT;
 661         }
 662         nexthdr_off += sizeof(_pptph);
 663         datalen -= sizeof(_pptph);
 664
 665         /* if it's not a control message we can't do anything with it */
 666         if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL ||
 667             ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) {
 668                 DEBUGP("not a control packet\n");
 669                 return NF_ACCEPT;
 670         }
 671
 672         oldsstate = info->sstate;
 673         oldcstate = info->cstate;
 674
 675         spin_lock_bh(&ip_pptp_lock);
 676
 677         /* FIXME: We just blindly assume that the control connection is always
 678          * established from PNS->PAC.  However, RFC makes no guarantee */
 679         if (dir == IP_CT_DIR_ORIGINAL)
 680                 /* client -> server (PNS -> PAC) */
 681                 ret = pptp_outbound_pkt(pskb, tcph, nexthdr_off, datalen, ct,
 682                                         ctinfo);
 683         else
 684                 /* server -> client (PAC -> PNS) */
 685                 ret = pptp_inbound_pkt(pskb, tcph, nexthdr_off, datalen, ct,
 686                                        ctinfo);
 687         DEBUGP("sstate: %d->%d, cstate: %d->%d\n",
 688                 oldsstate, info->sstate, oldcstate, info->cstate);
 689         spin_unlock_bh(&ip_pptp_lock);
 690
 691         return ret;
 692 }
 693
 694 /* control protocol helper */
 695 static struct ip_conntrack_helper pptp = {
 696         .list = { NULL, NULL },
 697         .name = "pptp",
 698         .me = THIS_MODULE,
 699         .max_expected = 2,
 700         .timeout = 5 * 60,
 701         .tuple = { .src = { .ip = 0,
 702                             .u = { .tcp = { .port =
 703                                     __constant_htons(PPTP_CONTROL_PORT) } }
 704                           },
 705                    .dst = { .ip = 0,
 706                             .u = { .all = 0 },
 707                             .protonum = IPPROTO_TCP
 708                           }
 709                  },
 710         .mask = { .src = { .ip = 0,
 711                            .u = { .tcp = { .port = __constant_htons(0xffff) } }
 712                          },
 713                   .dst = { .ip = 0,
 714                            .u = { .all = 0 },
 715                            .protonum = 0xff
 716                          }
 717                 },
 718         .help = conntrack_pptp_help
 719 };
 720
 721 extern void ip_ct_proto_gre_fini(void);
 722 extern int __init ip_ct_proto_gre_init(void);
 723
 724 /* ip_conntrack_pptp initialization */
 725 static int __init ip_conntrack_helper_pptp_init(void)
 726 {
 727         int retcode;
 728
 729         retcode = ip_ct_proto_gre_init();
 730         if (retcode < 0)
 731                 return retcode;
 732
 733         DEBUGP(" registering helper\n");
 734         if ((retcode = ip_conntrack_helper_register(&pptp))) {
 735                 printk(KERN_ERR "Unable to register conntrack application "
 736                                 "helper for pptp: %d\n", retcode);
 737                 ip_ct_proto_gre_fini();
 738                 return retcode;
 739         }
 740
 741         printk("ip_conntrack_pptp version %s loaded\n", IP_CT_PPTP_VERSION);
 742         return 0;
 743 }
 744
 745 static void __exit ip_conntrack_helper_pptp_fini(void)
 746 {
 747         ip_conntrack_helper_unregister(&pptp);
 748         ip_ct_proto_gre_fini();
 749         printk("ip_conntrack_pptp version %s unloaded\n", IP_CT_PPTP_VERSION);
 750 }
 751
 752 module_init(ip_conntrack_helper_pptp_init);
 753 module_exit(ip_conntrack_helper_pptp_fini);
 754
 755 EXPORT_SYMBOL(ip_nat_pptp_hook_outbound);
 756 EXPORT_SYMBOL(ip_nat_pptp_hook_inbound);
 757 EXPORT_SYMBOL(ip_nat_pptp_hook_exp_gre);
 758 EXPORT_SYMBOL(ip_nat_pptp_hook_expectfn);