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         typeof(ip_nat_pptp_hook_expectfn) ip_nat_pptp_expectfn;
 128
 129         DEBUGP("increasing timeouts\n");
 130
 131         /* increase timeout of GRE data channel conntrack entry */
 132         ct->proto.gre.timeout = PPTP_GRE_TIMEOUT;
 133         ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT;
 134
 135         /* Can you see how rusty this code is, compared with the pre-2.6.11
 136          * one? That's what happened to my shiny newnat of 2002 ;( -HW */
 137
 138         rcu_read_lock();
 139         ip_nat_pptp_expectfn = rcu_dereference(ip_nat_pptp_hook_expectfn);
 140         if (!ip_nat_pptp_expectfn) {
 141                 struct ip_conntrack_tuple inv_t;
 142                 struct ip_conntrack_expect *exp_other;
 143
 144                 /* obviously this tuple inversion only works until you do NAT */
 145                 invert_tuplepr(&inv_t, &exp->tuple);
 146                 DEBUGP("trying to unexpect other dir: ");
 147                 DUMP_TUPLE(&inv_t);
 148
 149                 exp_other = ip_conntrack_expect_find_get(&inv_t);
 150                 if (exp_other) {
 151                         /* delete other expectation.  */
 152                         DEBUGP("found\n");
 153                         ip_conntrack_unexpect_related(exp_other);
 154                         ip_conntrack_expect_put(exp_other);
 155                 } else {
 156                         DEBUGP("not found\n");
 157                 }
 158         } else {
 159                 /* we need more than simple inversion */
 160                 ip_nat_pptp_expectfn(ct, exp);
 161         }
 162         rcu_read_unlock();
 163 }
 164
 165 static int destroy_sibling_or_exp(const struct ip_conntrack_tuple *t)
 166 {
 167         struct ip_conntrack_tuple_hash *h;
 168         struct ip_conntrack_expect *exp;
 169
 170         DEBUGP("trying to timeout ct or exp for tuple ");
 171         DUMP_TUPLE(t);
 172
 173         h = ip_conntrack_find_get(t, NULL);
 174         if (h)  {
 175                 struct ip_conntrack *sibling = tuplehash_to_ctrack(h);
 176                 DEBUGP("setting timeout of conntrack %p to 0\n", sibling);
 177                 sibling->proto.gre.timeout = 0;
 178                 sibling->proto.gre.stream_timeout = 0;
 179                 if (del_timer(&sibling->timeout))
 180                         sibling->timeout.function((unsigned long)sibling);
 181                 ip_conntrack_put(sibling);
 182                 return 1;
 183         } else {
 184                 exp = ip_conntrack_expect_find_get(t);
 185                 if (exp) {
 186                         DEBUGP("unexpect_related of expect %p\n", exp);
 187                         ip_conntrack_unexpect_related(exp);
 188                         ip_conntrack_expect_put(exp);
 189                         return 1;
 190                 }
 191         }
 192
 193         return 0;
 194 }
 195
 196
 197 /* timeout GRE data connections */
 198 static void pptp_destroy_siblings(struct ip_conntrack *ct)
 199 {
 200         struct ip_conntrack_tuple t;
 201
 202         ip_ct_gre_keymap_destroy(ct);
 203         /* Since ct->sibling_list has literally rusted away in 2.6.11,
 204          * we now need another way to find out about our sibling
 205          * contrack and expects... -HW */
 206
 207         /* try original (pns->pac) tuple */
 208         memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t));
 209         t.dst.protonum = IPPROTO_GRE;
 210         t.src.u.gre.key = ct->help.ct_pptp_info.pns_call_id;
 211         t.dst.u.gre.key = ct->help.ct_pptp_info.pac_call_id;
 212
 213         if (!destroy_sibling_or_exp(&t))
 214                 DEBUGP("failed to timeout original pns->pac ct/exp\n");
 215
 216         /* try reply (pac->pns) tuple */
 217         memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t));
 218         t.dst.protonum = IPPROTO_GRE;
 219         t.src.u.gre.key = ct->help.ct_pptp_info.pac_call_id;
 220         t.dst.u.gre.key = ct->help.ct_pptp_info.pns_call_id;
 221
 222         if (!destroy_sibling_or_exp(&t))
 223                 DEBUGP("failed to timeout reply pac->pns ct/exp\n");
 224 }
 225
 226 /* expect GRE connections (PNS->PAC and PAC->PNS direction) */
 227 static inline int
 228 exp_gre(struct ip_conntrack *ct,
 229         __be16 callid,
 230         __be16 peer_callid)
 231 {
 232         struct ip_conntrack_expect *exp_orig, *exp_reply;
 233         int ret = 1;
 234         typeof(ip_nat_pptp_hook_exp_gre) ip_nat_pptp_exp_gre;
 235
 236         exp_orig = ip_conntrack_expect_alloc(ct);
 237         if (exp_orig == NULL)
 238                 goto out;
 239
 240         exp_reply = ip_conntrack_expect_alloc(ct);
 241         if (exp_reply == NULL)
 242                 goto out_put_orig;
 243
 244         /* original direction, PNS->PAC */
 245         exp_orig->tuple.src.ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip;
 246         exp_orig->tuple.src.u.gre.key = peer_callid;
 247         exp_orig->tuple.dst.ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip;
 248         exp_orig->tuple.dst.u.gre.key = callid;
 249         exp_orig->tuple.dst.protonum = IPPROTO_GRE;
 250
 251         exp_orig->mask.src.ip = htonl(0xffffffff);
 252         exp_orig->mask.src.u.all = 0;
 253         exp_orig->mask.dst.u.gre.key = htons(0xffff);
 254         exp_orig->mask.dst.ip = htonl(0xffffffff);
 255         exp_orig->mask.dst.protonum = 0xff;
 256
 257         exp_orig->master = ct;
 258         exp_orig->expectfn = pptp_expectfn;
 259         exp_orig->flags = 0;
 260
 261         /* both expectations are identical apart from tuple */
 262         memcpy(exp_reply, exp_orig, sizeof(*exp_reply));
 263
 264         /* reply direction, PAC->PNS */
 265         exp_reply->tuple.src.ip = ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip;
 266         exp_reply->tuple.src.u.gre.key = callid;
 267         exp_reply->tuple.dst.ip = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip;
 268         exp_reply->tuple.dst.u.gre.key = peer_callid;
 269         exp_reply->tuple.dst.protonum = IPPROTO_GRE;
 270
 271         ip_nat_pptp_exp_gre = rcu_dereference(ip_nat_pptp_hook_exp_gre);
 272         if (ip_nat_pptp_exp_gre)
 273                 ip_nat_pptp_exp_gre(exp_orig, exp_reply);
 274         if (ip_conntrack_expect_related(exp_orig) != 0)
 275                 goto out_put_both;
 276         if (ip_conntrack_expect_related(exp_reply) != 0)
 277                 goto out_unexpect_orig;
 278
 279         /* Add GRE keymap entries */
 280         if (ip_ct_gre_keymap_add(ct, &exp_orig->tuple, 0) != 0)
 281                 goto out_unexpect_both;
 282         if (ip_ct_gre_keymap_add(ct, &exp_reply->tuple, 1) != 0) {
 283                 ip_ct_gre_keymap_destroy(ct);
 284                 goto out_unexpect_both;
 285         }
 286         ret = 0;
 287
 288 out_put_both:
 289         ip_conntrack_expect_put(exp_reply);
 290 out_put_orig:
 291         ip_conntrack_expect_put(exp_orig);
 292 out:
 293         return ret;
 294
 295 out_unexpect_both:
 296         ip_conntrack_unexpect_related(exp_reply);
 297 out_unexpect_orig:
 298         ip_conntrack_unexpect_related(exp_orig);
 299         goto out_put_both;
 300 }
 301
 302 static inline int
 303 pptp_inbound_pkt(struct sk_buff **pskb,
 304                  struct PptpControlHeader *ctlh,
 305                  union pptp_ctrl_union *pptpReq,
 306                  unsigned int reqlen,
 307                  struct ip_conntrack *ct,
 308                  enum ip_conntrack_info ctinfo)
 309 {
 310         struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
 311         u_int16_t msg;
 312         __be16 cid = 0, pcid = 0;
 313         typeof(ip_nat_pptp_hook_inbound) ip_nat_pptp_inbound;
 314
 315         msg = ntohs(ctlh->messageType);
 316         DEBUGP("inbound control message %s\n", pptp_msg_name[msg]);
 317
 318         switch (msg) {
 319         case PPTP_START_SESSION_REPLY:
 320                 /* server confirms new control session */
 321                 if (info->sstate < PPTP_SESSION_REQUESTED)
 322                         goto invalid;
 323                 if (pptpReq->srep.resultCode == PPTP_START_OK)
 324                         info->sstate = PPTP_SESSION_CONFIRMED;
 325                 else
 326                         info->sstate = PPTP_SESSION_ERROR;
 327                 break;
 328
 329         case PPTP_STOP_SESSION_REPLY:
 330                 /* server confirms end of control session */
 331                 if (info->sstate > PPTP_SESSION_STOPREQ)
 332                         goto invalid;
 333                 if (pptpReq->strep.resultCode == PPTP_STOP_OK)
 334                         info->sstate = PPTP_SESSION_NONE;
 335                 else
 336                         info->sstate = PPTP_SESSION_ERROR;
 337                 break;
 338
 339         case PPTP_OUT_CALL_REPLY:
 340                 /* server accepted call, we now expect GRE frames */
 341                 if (info->sstate != PPTP_SESSION_CONFIRMED)
 342                         goto invalid;
 343                 if (info->cstate != PPTP_CALL_OUT_REQ &&
 344                     info->cstate != PPTP_CALL_OUT_CONF)
 345                         goto invalid;
 346
 347                 cid = pptpReq->ocack.callID;
 348                 pcid = pptpReq->ocack.peersCallID;
 349                 if (info->pns_call_id != pcid)
 350                         goto invalid;
 351                 DEBUGP("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg],
 352                         ntohs(cid), ntohs(pcid));
 353
 354                 if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) {
 355                         info->cstate = PPTP_CALL_OUT_CONF;
 356                         info->pac_call_id = cid;
 357                         exp_gre(ct, cid, pcid);
 358                 } else
 359                         info->cstate = PPTP_CALL_NONE;
 360                 break;
 361
 362         case PPTP_IN_CALL_REQUEST:
 363                 /* server tells us about incoming call request */
 364                 if (info->sstate != PPTP_SESSION_CONFIRMED)
 365                         goto invalid;
 366
 367                 cid = pptpReq->icreq.callID;
 368                 DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
 369                 info->cstate = PPTP_CALL_IN_REQ;
 370                 info->pac_call_id = cid;
 371                 break;
 372
 373         case PPTP_IN_CALL_CONNECT:
 374                 /* server tells us about incoming call established */
 375                 if (info->sstate != PPTP_SESSION_CONFIRMED)
 376                         goto invalid;
 377                 if (info->cstate != PPTP_CALL_IN_REP &&
 378                     info->cstate != PPTP_CALL_IN_CONF)
 379                         goto invalid;
 380
 381                 pcid = pptpReq->iccon.peersCallID;
 382                 cid = info->pac_call_id;
 383
 384                 if (info->pns_call_id != pcid)
 385                         goto invalid;
 386
 387                 DEBUGP("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid));
 388                 info->cstate = PPTP_CALL_IN_CONF;
 389
 390                 /* we expect a GRE connection from PAC to PNS */
 391                 exp_gre(ct, cid, pcid);
 392                 break;
 393
 394         case PPTP_CALL_DISCONNECT_NOTIFY:
 395                 /* server confirms disconnect */
 396                 cid = pptpReq->disc.callID;
 397                 DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
 398                 info->cstate = PPTP_CALL_NONE;
 399
 400                 /* untrack this call id, unexpect GRE packets */
 401                 pptp_destroy_siblings(ct);
 402                 break;
 403
 404         case PPTP_WAN_ERROR_NOTIFY:
 405         case PPTP_ECHO_REQUEST:
 406         case PPTP_ECHO_REPLY:
 407                 /* I don't have to explain these ;) */
 408                 break;
 409         default:
 410                 goto invalid;
 411         }
 412
 413         ip_nat_pptp_inbound = rcu_dereference(ip_nat_pptp_hook_inbound);
 414         if (ip_nat_pptp_inbound)
 415                 return ip_nat_pptp_inbound(pskb, ct, ctinfo, ctlh, pptpReq);
 416         return NF_ACCEPT;
 417
 418 invalid:
 419         DEBUGP("invalid %s: type=%d cid=%u pcid=%u "
 420                "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
 421                msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
 422                msg, ntohs(cid), ntohs(pcid),  info->cstate, info->sstate,
 423                ntohs(info->pns_call_id), ntohs(info->pac_call_id));
 424         return NF_ACCEPT;
 425 }
 426
 427 static inline int
 428 pptp_outbound_pkt(struct sk_buff **pskb,
 429                   struct PptpControlHeader *ctlh,
 430                   union pptp_ctrl_union *pptpReq,
 431                   unsigned int reqlen,
 432                   struct ip_conntrack *ct,
 433                   enum ip_conntrack_info ctinfo)
 434 {
 435         struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
 436         u_int16_t msg;
 437         __be16 cid = 0, pcid = 0;
 438         typeof(ip_nat_pptp_hook_outbound) ip_nat_pptp_outbound;
 439
 440         msg = ntohs(ctlh->messageType);
 441         DEBUGP("outbound control message %s\n", pptp_msg_name[msg]);
 442
 443         switch (msg) {
 444         case PPTP_START_SESSION_REQUEST:
 445                 /* client requests for new control session */
 446                 if (info->sstate != PPTP_SESSION_NONE)
 447                         goto invalid;
 448                 info->sstate = PPTP_SESSION_REQUESTED;
 449                 break;
 450         case PPTP_STOP_SESSION_REQUEST:
 451                 /* client requests end of control session */
 452                 info->sstate = PPTP_SESSION_STOPREQ;
 453                 break;
 454
 455         case PPTP_OUT_CALL_REQUEST:
 456                 /* client initiating connection to server */
 457                 if (info->sstate != PPTP_SESSION_CONFIRMED)
 458                         goto invalid;
 459                 info->cstate = PPTP_CALL_OUT_REQ;
 460                 /* track PNS call id */
 461                 cid = pptpReq->ocreq.callID;
 462                 DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
 463                 info->pns_call_id = cid;
 464                 break;
 465         case PPTP_IN_CALL_REPLY:
 466                 /* client answers incoming call */
 467                 if (info->cstate != PPTP_CALL_IN_REQ &&
 468                     info->cstate != PPTP_CALL_IN_REP)
 469                         goto invalid;
 470
 471                 cid = pptpReq->icack.callID;
 472                 pcid = pptpReq->icack.peersCallID;
 473                 if (info->pac_call_id != pcid)
 474                         goto invalid;
 475                 DEBUGP("%s, CID=%X PCID=%X\n", pptp_msg_name[msg],
 476                        ntohs(cid), ntohs(pcid));
 477
 478                 if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
 479                         /* part two of the three-way handshake */
 480                         info->cstate = PPTP_CALL_IN_REP;
 481                         info->pns_call_id = cid;
 482                 } else
 483                         info->cstate = PPTP_CALL_NONE;
 484                 break;
 485
 486         case PPTP_CALL_CLEAR_REQUEST:
 487                 /* client requests hangup of call */
 488                 if (info->sstate != PPTP_SESSION_CONFIRMED)
 489                         goto invalid;
 490                 /* FUTURE: iterate over all calls and check if
 491                  * call ID is valid.  We don't do this without newnat,
 492                  * because we only know about last call */
 493                 info->cstate = PPTP_CALL_CLEAR_REQ;
 494                 break;
 495         case PPTP_SET_LINK_INFO:
 496         case PPTP_ECHO_REQUEST:
 497         case PPTP_ECHO_REPLY:
 498                 /* I don't have to explain these ;) */
 499                 break;
 500         default:
 501                 goto invalid;
 502         }
 503
 504         ip_nat_pptp_outbound = rcu_dereference(ip_nat_pptp_hook_outbound);
 505         if (ip_nat_pptp_outbound)
 506                 return ip_nat_pptp_outbound(pskb, ct, ctinfo, ctlh, pptpReq);
 507         return NF_ACCEPT;
 508
 509 invalid:
 510         DEBUGP("invalid %s: type=%d cid=%u pcid=%u "
 511                "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
 512                msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],
 513                msg, ntohs(cid), ntohs(pcid),  info->cstate, info->sstate,
 514                ntohs(info->pns_call_id), ntohs(info->pac_call_id));
 515         return NF_ACCEPT;
 516 }
 517
 518 static const unsigned int pptp_msg_size[] = {
 519         [PPTP_START_SESSION_REQUEST]  = sizeof(struct PptpStartSessionRequest),
 520         [PPTP_START_SESSION_REPLY]    = sizeof(struct PptpStartSessionReply),
 521         [PPTP_STOP_SESSION_REQUEST]   = sizeof(struct PptpStopSessionRequest),
 522         [PPTP_STOP_SESSION_REPLY]     = sizeof(struct PptpStopSessionReply),
 523         [PPTP_OUT_CALL_REQUEST]       = sizeof(struct PptpOutCallRequest),
 524         [PPTP_OUT_CALL_REPLY]         = sizeof(struct PptpOutCallReply),
 525         [PPTP_IN_CALL_REQUEST]        = sizeof(struct PptpInCallRequest),
 526         [PPTP_IN_CALL_REPLY]          = sizeof(struct PptpInCallReply),
 527         [PPTP_IN_CALL_CONNECT]        = sizeof(struct PptpInCallConnected),
 528         [PPTP_CALL_CLEAR_REQUEST]     = sizeof(struct PptpClearCallRequest),
 529         [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
 530         [PPTP_WAN_ERROR_NOTIFY]       = sizeof(struct PptpWanErrorNotify),
 531         [PPTP_SET_LINK_INFO]          = sizeof(struct PptpSetLinkInfo),
 532 };
 533
 534 /* track caller id inside control connection, call expect_related */
 535 static int
 536 conntrack_pptp_help(struct sk_buff **pskb,
 537                     struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
 538
 539 {
 540         int dir = CTINFO2DIR(ctinfo);
 541         struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
 542         struct tcphdr _tcph, *tcph;
 543         struct pptp_pkt_hdr _pptph, *pptph;
 544         struct PptpControlHeader _ctlh, *ctlh;
 545         union pptp_ctrl_union _pptpReq, *pptpReq;
 546         unsigned int tcplen = (*pskb)->len - (*pskb)->nh.iph->ihl * 4;
 547         unsigned int datalen, reqlen, nexthdr_off;
 548         int oldsstate, oldcstate;
 549         int ret;
 550         u_int16_t msg;
 551
 552         /* don't do any tracking before tcp handshake complete */
 553         if (ctinfo != IP_CT_ESTABLISHED
 554             && ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) {
 555                 DEBUGP("ctinfo = %u, skipping\n", ctinfo);
 556                 return NF_ACCEPT;
 557         }
 558
 559         nexthdr_off = (*pskb)->nh.iph->ihl*4;
 560         tcph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_tcph), &_tcph);
 561         BUG_ON(!tcph);
 562         nexthdr_off += tcph->doff * 4;
 563         datalen = tcplen - tcph->doff * 4;
 564
 565         pptph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_pptph), &_pptph);
 566         if (!pptph) {
 567                 DEBUGP("no full PPTP header, can't track\n");
 568                 return NF_ACCEPT;
 569         }
 570         nexthdr_off += sizeof(_pptph);
 571         datalen -= sizeof(_pptph);
 572
 573         /* if it's not a control message we can't do anything with it */
 574         if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL ||
 575             ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) {
 576                 DEBUGP("not a control packet\n");
 577                 return NF_ACCEPT;
 578         }
 579
 580         ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh);
 581         if (!ctlh)
 582                 return NF_ACCEPT;
 583         nexthdr_off += sizeof(_ctlh);
 584         datalen -= sizeof(_ctlh);
 585
 586         reqlen = datalen;
 587         msg = ntohs(ctlh->messageType);
 588         if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
 589                 return NF_ACCEPT;
 590         if (reqlen > sizeof(*pptpReq))
 591                 reqlen = sizeof(*pptpReq);
 592
 593         pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq);
 594         if (!pptpReq)
 595                 return NF_ACCEPT;
 596
 597         oldsstate = info->sstate;
 598         oldcstate = info->cstate;
 599
 600         spin_lock_bh(&ip_pptp_lock);
 601
 602         /* FIXME: We just blindly assume that the control connection is always
 603          * established from PNS->PAC.  However, RFC makes no guarantee */
 604         if (dir == IP_CT_DIR_ORIGINAL)
 605                 /* client -> server (PNS -> PAC) */
 606                 ret = pptp_outbound_pkt(pskb, ctlh, pptpReq, reqlen, ct,
 607                                         ctinfo);
 608         else
 609                 /* server -> client (PAC -> PNS) */
 610                 ret = pptp_inbound_pkt(pskb, ctlh, pptpReq, reqlen, ct,
 611                                        ctinfo);
 612         DEBUGP("sstate: %d->%d, cstate: %d->%d\n",
 613                 oldsstate, info->sstate, oldcstate, info->cstate);
 614         spin_unlock_bh(&ip_pptp_lock);
 615
 616         return ret;
 617 }
 618
 619 /* control protocol helper */
 620 static struct ip_conntrack_helper pptp = {
 621         .list = { NULL, NULL },
 622         .name = "pptp",
 623         .me = THIS_MODULE,
 624         .max_expected = 2,
 625         .timeout = 5 * 60,
 626         .tuple = { .src = { .ip = 0,
 627                             .u = { .tcp = { .port =
 628                                     __constant_htons(PPTP_CONTROL_PORT) } }
 629                           },
 630                    .dst = { .ip = 0,
 631                             .u = { .all = 0 },
 632                             .protonum = IPPROTO_TCP
 633                           }
 634                  },
 635         .mask = { .src = { .ip = 0,
 636                            .u = { .tcp = { .port = __constant_htons(0xffff) } }
 637                          },
 638                   .dst = { .ip = 0,
 639                            .u = { .all = 0 },
 640                            .protonum = 0xff
 641                          }
 642                 },
 643         .help = conntrack_pptp_help,
 644         .destroy = pptp_destroy_siblings,
 645 };
 646
 647 extern void ip_ct_proto_gre_fini(void);
 648 extern int __init ip_ct_proto_gre_init(void);
 649
 650 /* ip_conntrack_pptp initialization */
 651 static int __init ip_conntrack_helper_pptp_init(void)
 652 {
 653         int retcode;
 654
 655         retcode = ip_ct_proto_gre_init();
 656         if (retcode < 0)
 657                 return retcode;
 658
 659         DEBUGP(" registering helper\n");
 660         if ((retcode = ip_conntrack_helper_register(&pptp))) {
 661                 printk(KERN_ERR "Unable to register conntrack application "
 662                                 "helper for pptp: %d\n", retcode);
 663                 ip_ct_proto_gre_fini();
 664                 return retcode;
 665         }
 666
 667         printk("ip_conntrack_pptp version %s loaded\n", IP_CT_PPTP_VERSION);
 668         return 0;
 669 }
 670
 671 static void __exit ip_conntrack_helper_pptp_fini(void)
 672 {
 673         ip_conntrack_helper_unregister(&pptp);
 674         ip_ct_proto_gre_fini();
 675         printk("ip_conntrack_pptp version %s unloaded\n", IP_CT_PPTP_VERSION);
 676 }
 677
 678 module_init(ip_conntrack_helper_pptp_init);
 679 module_exit(ip_conntrack_helper_pptp_fini);
 680
 681 EXPORT_SYMBOL(ip_nat_pptp_hook_outbound);
 682 EXPORT_SYMBOL(ip_nat_pptp_hook_inbound);
 683 EXPORT_SYMBOL(ip_nat_pptp_hook_exp_gre);
 684 EXPORT_SYMBOL(ip_nat_pptp_hook_expectfn);