Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 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/config.h> |
| 50 | #include <linux/module.h> |
| 51 | #include <linux/netfilter.h> |
| 52 | #include <linux/ip.h> |
| 53 | #include <net/checksum.h> |
| 54 | #include <net/tcp.h> |
| 55 | |
| 56 | #include <linux/netfilter_ipv4/ip_conntrack.h> |
| 57 | #include <linux/netfilter_ipv4/ip_conntrack_core.h> |
| 58 | #include <linux/netfilter_ipv4/ip_conntrack_helper.h> |
| 59 | #include <linux/netfilter_ipv4/ip_conntrack_proto_gre.h> |
| 60 | #include <linux/netfilter_ipv4/ip_conntrack_pptp.h> |
| 61 | |
| 62 | #define IP_CT_PPTP_VERSION "3.1" |
| 63 | |
| 64 | MODULE_LICENSE("GPL"); |
| 65 | MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); |
| 66 | MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP"); |
| 67 | |
| 68 | static DEFINE_SPINLOCK(ip_pptp_lock); |
| 69 | |
| 70 | int |
| 71 | (*ip_nat_pptp_hook_outbound)(struct sk_buff **pskb, |
| 72 | struct ip_conntrack *ct, |
| 73 | enum ip_conntrack_info ctinfo, |
| 74 | struct PptpControlHeader *ctlh, |
| 75 | union pptp_ctrl_union *pptpReq); |
| 76 | |
| 77 | int |
| 78 | (*ip_nat_pptp_hook_inbound)(struct sk_buff **pskb, |
| 79 | struct ip_conntrack *ct, |
| 80 | enum ip_conntrack_info ctinfo, |
| 81 | struct PptpControlHeader *ctlh, |
| 82 | union pptp_ctrl_union *pptpReq); |
| 83 | |
| 84 | int |
| 85 | (*ip_nat_pptp_hook_exp_gre)(struct ip_conntrack_expect *expect_orig, |
| 86 | struct ip_conntrack_expect *expect_reply); |
| 87 | |
| 88 | void |
| 89 | (*ip_nat_pptp_hook_expectfn)(struct ip_conntrack *ct, |
| 90 | struct ip_conntrack_expect *exp); |
| 91 | |
| 92 | #if 0 |
| 93 | /* PptpControlMessageType names */ |
| 94 | const char *pptp_msg_name[] = { |
| 95 | "UNKNOWN_MESSAGE", |
| 96 | "START_SESSION_REQUEST", |
| 97 | "START_SESSION_REPLY", |
| 98 | "STOP_SESSION_REQUEST", |
| 99 | "STOP_SESSION_REPLY", |
| 100 | "ECHO_REQUEST", |
| 101 | "ECHO_REPLY", |
| 102 | "OUT_CALL_REQUEST", |
| 103 | "OUT_CALL_REPLY", |
| 104 | "IN_CALL_REQUEST", |
| 105 | "IN_CALL_REPLY", |
| 106 | "IN_CALL_CONNECT", |
| 107 | "CALL_CLEAR_REQUEST", |
| 108 | "CALL_DISCONNECT_NOTIFY", |
| 109 | "WAN_ERROR_NOTIFY", |
| 110 | "SET_LINK_INFO" |
| 111 | }; |
| 112 | EXPORT_SYMBOL(pptp_msg_name); |
| 113 | #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, __FUNCTION__, ## args) |
| 114 | #else |
| 115 | #define DEBUGP(format, args...) |
| 116 | #endif |
| 117 | |
| 118 | #define SECS *HZ |
| 119 | #define MINS * 60 SECS |
| 120 | #define HOURS * 60 MINS |
| 121 | |
| 122 | #define PPTP_GRE_TIMEOUT (10 MINS) |
| 123 | #define PPTP_GRE_STREAM_TIMEOUT (5 HOURS) |
| 124 | |
| 125 | static void pptp_expectfn(struct ip_conntrack *ct, |
| 126 | struct ip_conntrack_expect *exp) |
| 127 | { |
| 128 | DEBUGP("increasing timeouts\n"); |
| 129 | |
| 130 | /* increase timeout of GRE data channel conntrack entry */ |
| 131 | ct->proto.gre.timeout = PPTP_GRE_TIMEOUT; |
| 132 | ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT; |
| 133 | |
| 134 | /* Can you see how rusty this code is, compared with the pre-2.6.11 |
| 135 | * one? That's what happened to my shiny newnat of 2002 ;( -HW */ |
| 136 | |
| 137 | if (!ip_nat_pptp_hook_expectfn) { |
| 138 | struct ip_conntrack_tuple inv_t; |
| 139 | struct ip_conntrack_expect *exp_other; |
| 140 | |
| 141 | /* obviously this tuple inversion only works until you do NAT */ |
| 142 | invert_tuplepr(&inv_t, &exp->tuple); |
| 143 | DEBUGP("trying to unexpect other dir: "); |
| 144 | DUMP_TUPLE(&inv_t); |
| 145 | |
| 146 | exp_other = ip_conntrack_expect_find(&inv_t); |
| 147 | if (exp_other) { |
| 148 | /* delete other expectation. */ |
| 149 | DEBUGP("found\n"); |
| 150 | ip_conntrack_unexpect_related(exp_other); |
| 151 | ip_conntrack_expect_put(exp_other); |
| 152 | } else { |
| 153 | DEBUGP("not found\n"); |
| 154 | } |
| 155 | } else { |
| 156 | /* we need more than simple inversion */ |
| 157 | ip_nat_pptp_hook_expectfn(ct, exp); |
| 158 | } |
| 159 | } |
| 160 | |
| 161 | static int destroy_sibling_or_exp(const struct ip_conntrack_tuple *t) |
| 162 | { |
| 163 | struct ip_conntrack_tuple_hash *h; |
| 164 | struct ip_conntrack_expect *exp; |
| 165 | |
| 166 | DEBUGP("trying to timeout ct or exp for tuple "); |
| 167 | DUMP_TUPLE(t); |
| 168 | |
| 169 | h = ip_conntrack_find_get(t, NULL); |
| 170 | if (h) { |
| 171 | struct ip_conntrack *sibling = tuplehash_to_ctrack(h); |
| 172 | DEBUGP("setting timeout of conntrack %p to 0\n", sibling); |
| 173 | sibling->proto.gre.timeout = 0; |
| 174 | sibling->proto.gre.stream_timeout = 0; |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 175 | if (del_timer(&sibling->timeout)) |
| 176 | sibling->timeout.function((unsigned long)sibling); |
| 177 | ip_conntrack_put(sibling); |
| 178 | return 1; |
| 179 | } else { |
| 180 | exp = ip_conntrack_expect_find(t); |
| 181 | if (exp) { |
| 182 | DEBUGP("unexpect_related of expect %p\n", exp); |
| 183 | ip_conntrack_unexpect_related(exp); |
| 184 | ip_conntrack_expect_put(exp); |
| 185 | return 1; |
| 186 | } |
| 187 | } |
| 188 | |
| 189 | return 0; |
| 190 | } |
| 191 | |
| 192 | |
| 193 | /* timeout GRE data connections */ |
| 194 | static void pptp_destroy_siblings(struct ip_conntrack *ct) |
| 195 | { |
| 196 | struct ip_conntrack_tuple t; |
| 197 | |
| 198 | /* Since ct->sibling_list has literally rusted away in 2.6.11, |
| 199 | * we now need another way to find out about our sibling |
| 200 | * contrack and expects... -HW */ |
| 201 | |
| 202 | /* try original (pns->pac) tuple */ |
| 203 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t)); |
| 204 | t.dst.protonum = IPPROTO_GRE; |
| 205 | t.src.u.gre.key = htons(ct->help.ct_pptp_info.pns_call_id); |
| 206 | t.dst.u.gre.key = htons(ct->help.ct_pptp_info.pac_call_id); |
| 207 | |
| 208 | if (!destroy_sibling_or_exp(&t)) |
| 209 | DEBUGP("failed to timeout original pns->pac ct/exp\n"); |
| 210 | |
| 211 | /* try reply (pac->pns) tuple */ |
| 212 | memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t)); |
| 213 | t.dst.protonum = IPPROTO_GRE; |
| 214 | t.src.u.gre.key = htons(ct->help.ct_pptp_info.pac_call_id); |
| 215 | t.dst.u.gre.key = htons(ct->help.ct_pptp_info.pns_call_id); |
| 216 | |
| 217 | if (!destroy_sibling_or_exp(&t)) |
| 218 | DEBUGP("failed to timeout reply pac->pns ct/exp\n"); |
| 219 | } |
| 220 | |
| 221 | /* expect GRE connections (PNS->PAC and PAC->PNS direction) */ |
| 222 | static inline int |
| 223 | exp_gre(struct ip_conntrack *master, |
| 224 | u_int32_t seq, |
Alexey Dobriyan | 6749720 | 2005-09-22 23:45:24 -0700 | [diff] [blame] | 225 | __be16 callid, |
| 226 | __be16 peer_callid) |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 227 | { |
| 228 | struct ip_conntrack_tuple inv_tuple; |
| 229 | struct ip_conntrack_tuple exp_tuples[] = { |
| 230 | /* tuple in original direction, PNS->PAC */ |
| 231 | { .src = { .ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip, |
| 232 | .u = { .gre = { .key = peer_callid } } |
| 233 | }, |
| 234 | .dst = { .ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip, |
| 235 | .u = { .gre = { .key = callid } }, |
| 236 | .protonum = IPPROTO_GRE |
| 237 | }, |
| 238 | }, |
| 239 | /* tuple in reply direction, PAC->PNS */ |
| 240 | { .src = { .ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip, |
| 241 | .u = { .gre = { .key = callid } } |
| 242 | }, |
| 243 | .dst = { .ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip, |
| 244 | .u = { .gre = { .key = peer_callid } }, |
| 245 | .protonum = IPPROTO_GRE |
| 246 | }, |
| 247 | } |
| 248 | }; |
| 249 | struct ip_conntrack_expect *exp_orig, *exp_reply; |
| 250 | int ret = 1; |
| 251 | |
| 252 | exp_orig = ip_conntrack_expect_alloc(master); |
| 253 | if (exp_orig == NULL) |
| 254 | goto out; |
| 255 | |
| 256 | exp_reply = ip_conntrack_expect_alloc(master); |
| 257 | if (exp_reply == NULL) |
| 258 | goto out_put_orig; |
| 259 | |
| 260 | memcpy(&exp_orig->tuple, &exp_tuples[0], sizeof(exp_orig->tuple)); |
| 261 | |
| 262 | exp_orig->mask.src.ip = 0xffffffff; |
| 263 | exp_orig->mask.src.u.all = 0; |
| 264 | exp_orig->mask.dst.u.all = 0; |
Alexey Dobriyan | 6749720 | 2005-09-22 23:45:24 -0700 | [diff] [blame] | 265 | exp_orig->mask.dst.u.gre.key = htons(0xffff); |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 266 | exp_orig->mask.dst.ip = 0xffffffff; |
| 267 | exp_orig->mask.dst.protonum = 0xff; |
| 268 | |
| 269 | exp_orig->master = master; |
| 270 | exp_orig->expectfn = pptp_expectfn; |
| 271 | exp_orig->flags = 0; |
| 272 | |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 273 | /* both expectations are identical apart from tuple */ |
| 274 | memcpy(exp_reply, exp_orig, sizeof(*exp_reply)); |
| 275 | memcpy(&exp_reply->tuple, &exp_tuples[1], sizeof(exp_reply->tuple)); |
| 276 | |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 277 | if (ip_nat_pptp_hook_exp_gre) |
| 278 | ret = ip_nat_pptp_hook_exp_gre(exp_orig, exp_reply); |
| 279 | else { |
| 280 | |
| 281 | DEBUGP("calling expect_related PNS->PAC"); |
| 282 | DUMP_TUPLE(&exp_orig->tuple); |
| 283 | |
| 284 | if (ip_conntrack_expect_related(exp_orig) != 0) { |
| 285 | DEBUGP("cannot expect_related()\n"); |
| 286 | goto out_put_both; |
| 287 | } |
| 288 | |
| 289 | DEBUGP("calling expect_related PAC->PNS"); |
| 290 | DUMP_TUPLE(&exp_reply->tuple); |
| 291 | |
| 292 | if (ip_conntrack_expect_related(exp_reply) != 0) { |
| 293 | DEBUGP("cannot expect_related()\n"); |
| 294 | goto out_unexpect_orig; |
| 295 | } |
| 296 | |
| 297 | /* Add GRE keymap entries */ |
| 298 | if (ip_ct_gre_keymap_add(master, &exp_reply->tuple, 0) != 0) { |
| 299 | DEBUGP("cannot keymap_add() exp\n"); |
| 300 | goto out_unexpect_both; |
| 301 | } |
| 302 | |
| 303 | invert_tuplepr(&inv_tuple, &exp_reply->tuple); |
| 304 | if (ip_ct_gre_keymap_add(master, &inv_tuple, 1) != 0) { |
| 305 | ip_ct_gre_keymap_destroy(master); |
| 306 | DEBUGP("cannot keymap_add() exp_inv\n"); |
| 307 | goto out_unexpect_both; |
| 308 | } |
| 309 | ret = 0; |
| 310 | } |
| 311 | |
| 312 | out_put_both: |
| 313 | ip_conntrack_expect_put(exp_reply); |
| 314 | out_put_orig: |
| 315 | ip_conntrack_expect_put(exp_orig); |
| 316 | out: |
| 317 | return ret; |
| 318 | |
| 319 | out_unexpect_both: |
| 320 | ip_conntrack_unexpect_related(exp_reply); |
| 321 | out_unexpect_orig: |
| 322 | ip_conntrack_unexpect_related(exp_orig); |
| 323 | goto out_put_both; |
| 324 | } |
| 325 | |
| 326 | static inline int |
| 327 | pptp_inbound_pkt(struct sk_buff **pskb, |
| 328 | struct tcphdr *tcph, |
| 329 | unsigned int nexthdr_off, |
| 330 | unsigned int datalen, |
| 331 | struct ip_conntrack *ct, |
| 332 | enum ip_conntrack_info ctinfo) |
| 333 | { |
| 334 | struct PptpControlHeader _ctlh, *ctlh; |
| 335 | unsigned int reqlen; |
| 336 | union pptp_ctrl_union _pptpReq, *pptpReq; |
| 337 | struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info; |
Alexey Dobriyan | 6749720 | 2005-09-22 23:45:24 -0700 | [diff] [blame] | 338 | u_int16_t msg; |
| 339 | __be16 *cid, *pcid; |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 340 | u_int32_t seq; |
| 341 | |
| 342 | ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh); |
| 343 | if (!ctlh) { |
| 344 | DEBUGP("error during skb_header_pointer\n"); |
| 345 | return NF_ACCEPT; |
| 346 | } |
| 347 | nexthdr_off += sizeof(_ctlh); |
| 348 | datalen -= sizeof(_ctlh); |
| 349 | |
| 350 | reqlen = datalen; |
| 351 | if (reqlen > sizeof(*pptpReq)) |
| 352 | reqlen = sizeof(*pptpReq); |
| 353 | pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq); |
| 354 | if (!pptpReq) { |
| 355 | DEBUGP("error during skb_header_pointer\n"); |
| 356 | return NF_ACCEPT; |
| 357 | } |
| 358 | |
| 359 | msg = ntohs(ctlh->messageType); |
| 360 | DEBUGP("inbound control message %s\n", pptp_msg_name[msg]); |
| 361 | |
| 362 | switch (msg) { |
| 363 | case PPTP_START_SESSION_REPLY: |
| 364 | if (reqlen < sizeof(_pptpReq.srep)) { |
| 365 | DEBUGP("%s: short packet\n", pptp_msg_name[msg]); |
| 366 | break; |
| 367 | } |
| 368 | |
| 369 | /* server confirms new control session */ |
| 370 | if (info->sstate < PPTP_SESSION_REQUESTED) { |
| 371 | DEBUGP("%s without START_SESS_REQUEST\n", |
| 372 | pptp_msg_name[msg]); |
| 373 | break; |
| 374 | } |
| 375 | if (pptpReq->srep.resultCode == PPTP_START_OK) |
| 376 | info->sstate = PPTP_SESSION_CONFIRMED; |
| 377 | else |
| 378 | info->sstate = PPTP_SESSION_ERROR; |
| 379 | break; |
| 380 | |
| 381 | case PPTP_STOP_SESSION_REPLY: |
| 382 | if (reqlen < sizeof(_pptpReq.strep)) { |
| 383 | DEBUGP("%s: short packet\n", pptp_msg_name[msg]); |
| 384 | break; |
| 385 | } |
| 386 | |
| 387 | /* server confirms end of control session */ |
| 388 | if (info->sstate > PPTP_SESSION_STOPREQ) { |
| 389 | DEBUGP("%s without STOP_SESS_REQUEST\n", |
| 390 | pptp_msg_name[msg]); |
| 391 | break; |
| 392 | } |
| 393 | if (pptpReq->strep.resultCode == PPTP_STOP_OK) |
| 394 | info->sstate = PPTP_SESSION_NONE; |
| 395 | else |
| 396 | info->sstate = PPTP_SESSION_ERROR; |
| 397 | break; |
| 398 | |
| 399 | case PPTP_OUT_CALL_REPLY: |
| 400 | if (reqlen < sizeof(_pptpReq.ocack)) { |
| 401 | DEBUGP("%s: short packet\n", pptp_msg_name[msg]); |
| 402 | break; |
| 403 | } |
| 404 | |
| 405 | /* server accepted call, we now expect GRE frames */ |
| 406 | if (info->sstate != PPTP_SESSION_CONFIRMED) { |
| 407 | DEBUGP("%s but no session\n", pptp_msg_name[msg]); |
| 408 | break; |
| 409 | } |
| 410 | if (info->cstate != PPTP_CALL_OUT_REQ && |
| 411 | info->cstate != PPTP_CALL_OUT_CONF) { |
| 412 | DEBUGP("%s without OUTCALL_REQ\n", pptp_msg_name[msg]); |
| 413 | break; |
| 414 | } |
| 415 | if (pptpReq->ocack.resultCode != PPTP_OUTCALL_CONNECT) { |
| 416 | info->cstate = PPTP_CALL_NONE; |
| 417 | break; |
| 418 | } |
| 419 | |
| 420 | cid = &pptpReq->ocack.callID; |
| 421 | pcid = &pptpReq->ocack.peersCallID; |
| 422 | |
| 423 | info->pac_call_id = ntohs(*cid); |
| 424 | |
| 425 | if (htons(info->pns_call_id) != *pcid) { |
| 426 | DEBUGP("%s for unknown callid %u\n", |
| 427 | pptp_msg_name[msg], ntohs(*pcid)); |
| 428 | break; |
| 429 | } |
| 430 | |
| 431 | DEBUGP("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg], |
| 432 | ntohs(*cid), ntohs(*pcid)); |
| 433 | |
| 434 | info->cstate = PPTP_CALL_OUT_CONF; |
| 435 | |
| 436 | seq = ntohl(tcph->seq) + sizeof(struct pptp_pkt_hdr) |
| 437 | + sizeof(struct PptpControlHeader) |
| 438 | + ((void *)pcid - (void *)pptpReq); |
| 439 | |
| 440 | if (exp_gre(ct, seq, *cid, *pcid) != 0) |
| 441 | printk("ip_conntrack_pptp: error during exp_gre\n"); |
| 442 | break; |
| 443 | |
| 444 | case PPTP_IN_CALL_REQUEST: |
| 445 | if (reqlen < sizeof(_pptpReq.icack)) { |
| 446 | DEBUGP("%s: short packet\n", pptp_msg_name[msg]); |
| 447 | break; |
| 448 | } |
| 449 | |
| 450 | /* server tells us about incoming call request */ |
| 451 | if (info->sstate != PPTP_SESSION_CONFIRMED) { |
| 452 | DEBUGP("%s but no session\n", pptp_msg_name[msg]); |
| 453 | break; |
| 454 | } |
| 455 | pcid = &pptpReq->icack.peersCallID; |
| 456 | DEBUGP("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(*pcid)); |
| 457 | info->cstate = PPTP_CALL_IN_REQ; |
| 458 | info->pac_call_id = ntohs(*pcid); |
| 459 | break; |
| 460 | |
| 461 | case PPTP_IN_CALL_CONNECT: |
| 462 | if (reqlen < sizeof(_pptpReq.iccon)) { |
| 463 | DEBUGP("%s: short packet\n", pptp_msg_name[msg]); |
| 464 | break; |
| 465 | } |
| 466 | |
| 467 | /* server tells us about incoming call established */ |
| 468 | if (info->sstate != PPTP_SESSION_CONFIRMED) { |
| 469 | DEBUGP("%s but no session\n", pptp_msg_name[msg]); |
| 470 | break; |
| 471 | } |
| 472 | if (info->sstate != PPTP_CALL_IN_REP |
| 473 | && info->sstate != PPTP_CALL_IN_CONF) { |
| 474 | DEBUGP("%s but never sent IN_CALL_REPLY\n", |
| 475 | pptp_msg_name[msg]); |
| 476 | break; |
| 477 | } |
| 478 | |
| 479 | pcid = &pptpReq->iccon.peersCallID; |
| 480 | cid = &info->pac_call_id; |
| 481 | |
| 482 | if (info->pns_call_id != ntohs(*pcid)) { |
| 483 | DEBUGP("%s for unknown CallID %u\n", |
Harald Welte | 0ae5d25 | 2005-09-22 23:44:58 -0700 | [diff] [blame] | 484 | pptp_msg_name[msg], ntohs(*pcid)); |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 485 | break; |
| 486 | } |
| 487 | |
| 488 | DEBUGP("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(*pcid)); |
| 489 | info->cstate = PPTP_CALL_IN_CONF; |
| 490 | |
| 491 | /* we expect a GRE connection from PAC to PNS */ |
| 492 | seq = ntohl(tcph->seq) + sizeof(struct pptp_pkt_hdr) |
| 493 | + sizeof(struct PptpControlHeader) |
| 494 | + ((void *)pcid - (void *)pptpReq); |
| 495 | |
| 496 | if (exp_gre(ct, seq, *cid, *pcid) != 0) |
| 497 | printk("ip_conntrack_pptp: error during exp_gre\n"); |
| 498 | |
| 499 | break; |
| 500 | |
| 501 | case PPTP_CALL_DISCONNECT_NOTIFY: |
| 502 | if (reqlen < sizeof(_pptpReq.disc)) { |
| 503 | DEBUGP("%s: short packet\n", pptp_msg_name[msg]); |
| 504 | break; |
| 505 | } |
| 506 | |
| 507 | /* server confirms disconnect */ |
| 508 | cid = &pptpReq->disc.callID; |
| 509 | DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(*cid)); |
| 510 | info->cstate = PPTP_CALL_NONE; |
| 511 | |
| 512 | /* untrack this call id, unexpect GRE packets */ |
| 513 | pptp_destroy_siblings(ct); |
| 514 | break; |
| 515 | |
| 516 | case PPTP_WAN_ERROR_NOTIFY: |
| 517 | break; |
| 518 | |
| 519 | case PPTP_ECHO_REQUEST: |
| 520 | case PPTP_ECHO_REPLY: |
| 521 | /* I don't have to explain these ;) */ |
| 522 | break; |
| 523 | default: |
| 524 | DEBUGP("invalid %s (TY=%d)\n", (msg <= PPTP_MSG_MAX) |
| 525 | ? pptp_msg_name[msg]:pptp_msg_name[0], msg); |
| 526 | break; |
| 527 | } |
| 528 | |
| 529 | |
| 530 | if (ip_nat_pptp_hook_inbound) |
| 531 | return ip_nat_pptp_hook_inbound(pskb, ct, ctinfo, ctlh, |
| 532 | pptpReq); |
| 533 | |
| 534 | return NF_ACCEPT; |
| 535 | |
| 536 | } |
| 537 | |
| 538 | static inline int |
| 539 | pptp_outbound_pkt(struct sk_buff **pskb, |
| 540 | struct tcphdr *tcph, |
| 541 | unsigned int nexthdr_off, |
| 542 | unsigned int datalen, |
| 543 | struct ip_conntrack *ct, |
| 544 | enum ip_conntrack_info ctinfo) |
| 545 | { |
| 546 | struct PptpControlHeader _ctlh, *ctlh; |
| 547 | unsigned int reqlen; |
| 548 | union pptp_ctrl_union _pptpReq, *pptpReq; |
| 549 | struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info; |
Alexey Dobriyan | 6749720 | 2005-09-22 23:45:24 -0700 | [diff] [blame] | 550 | u_int16_t msg; |
| 551 | __be16 *cid, *pcid; |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 552 | |
| 553 | ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh); |
| 554 | if (!ctlh) |
| 555 | return NF_ACCEPT; |
| 556 | nexthdr_off += sizeof(_ctlh); |
| 557 | datalen -= sizeof(_ctlh); |
| 558 | |
| 559 | reqlen = datalen; |
| 560 | if (reqlen > sizeof(*pptpReq)) |
| 561 | reqlen = sizeof(*pptpReq); |
| 562 | pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq); |
| 563 | if (!pptpReq) |
| 564 | return NF_ACCEPT; |
| 565 | |
| 566 | msg = ntohs(ctlh->messageType); |
| 567 | DEBUGP("outbound control message %s\n", pptp_msg_name[msg]); |
| 568 | |
| 569 | switch (msg) { |
| 570 | case PPTP_START_SESSION_REQUEST: |
| 571 | /* client requests for new control session */ |
| 572 | if (info->sstate != PPTP_SESSION_NONE) { |
| 573 | DEBUGP("%s but we already have one", |
| 574 | pptp_msg_name[msg]); |
| 575 | } |
| 576 | info->sstate = PPTP_SESSION_REQUESTED; |
| 577 | break; |
| 578 | case PPTP_STOP_SESSION_REQUEST: |
| 579 | /* client requests end of control session */ |
| 580 | info->sstate = PPTP_SESSION_STOPREQ; |
| 581 | break; |
| 582 | |
| 583 | case PPTP_OUT_CALL_REQUEST: |
| 584 | if (reqlen < sizeof(_pptpReq.ocreq)) { |
| 585 | DEBUGP("%s: short packet\n", pptp_msg_name[msg]); |
| 586 | /* FIXME: break; */ |
| 587 | } |
| 588 | |
| 589 | /* client initiating connection to server */ |
| 590 | if (info->sstate != PPTP_SESSION_CONFIRMED) { |
| 591 | DEBUGP("%s but no session\n", |
| 592 | pptp_msg_name[msg]); |
| 593 | break; |
| 594 | } |
| 595 | info->cstate = PPTP_CALL_OUT_REQ; |
| 596 | /* track PNS call id */ |
| 597 | cid = &pptpReq->ocreq.callID; |
| 598 | DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(*cid)); |
| 599 | info->pns_call_id = ntohs(*cid); |
| 600 | break; |
| 601 | case PPTP_IN_CALL_REPLY: |
| 602 | if (reqlen < sizeof(_pptpReq.icack)) { |
| 603 | DEBUGP("%s: short packet\n", pptp_msg_name[msg]); |
| 604 | break; |
| 605 | } |
| 606 | |
| 607 | /* client answers incoming call */ |
| 608 | if (info->cstate != PPTP_CALL_IN_REQ |
| 609 | && info->cstate != PPTP_CALL_IN_REP) { |
| 610 | DEBUGP("%s without incall_req\n", |
| 611 | pptp_msg_name[msg]); |
| 612 | break; |
| 613 | } |
| 614 | if (pptpReq->icack.resultCode != PPTP_INCALL_ACCEPT) { |
| 615 | info->cstate = PPTP_CALL_NONE; |
| 616 | break; |
| 617 | } |
| 618 | pcid = &pptpReq->icack.peersCallID; |
| 619 | if (info->pac_call_id != ntohs(*pcid)) { |
| 620 | DEBUGP("%s for unknown call %u\n", |
| 621 | pptp_msg_name[msg], ntohs(*pcid)); |
| 622 | break; |
| 623 | } |
| 624 | DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(*pcid)); |
| 625 | /* part two of the three-way handshake */ |
| 626 | info->cstate = PPTP_CALL_IN_REP; |
| 627 | info->pns_call_id = ntohs(pptpReq->icack.callID); |
| 628 | break; |
| 629 | |
| 630 | case PPTP_CALL_CLEAR_REQUEST: |
| 631 | /* client requests hangup of call */ |
| 632 | if (info->sstate != PPTP_SESSION_CONFIRMED) { |
| 633 | DEBUGP("CLEAR_CALL but no session\n"); |
| 634 | break; |
| 635 | } |
| 636 | /* FUTURE: iterate over all calls and check if |
| 637 | * call ID is valid. We don't do this without newnat, |
| 638 | * because we only know about last call */ |
| 639 | info->cstate = PPTP_CALL_CLEAR_REQ; |
| 640 | break; |
| 641 | case PPTP_SET_LINK_INFO: |
| 642 | break; |
| 643 | case PPTP_ECHO_REQUEST: |
| 644 | case PPTP_ECHO_REPLY: |
| 645 | /* I don't have to explain these ;) */ |
| 646 | break; |
| 647 | default: |
| 648 | DEBUGP("invalid %s (TY=%d)\n", (msg <= PPTP_MSG_MAX)? |
| 649 | pptp_msg_name[msg]:pptp_msg_name[0], msg); |
| 650 | /* unknown: no need to create GRE masq table entry */ |
| 651 | break; |
| 652 | } |
| 653 | |
| 654 | if (ip_nat_pptp_hook_outbound) |
| 655 | return ip_nat_pptp_hook_outbound(pskb, ct, ctinfo, ctlh, |
| 656 | pptpReq); |
| 657 | |
| 658 | return NF_ACCEPT; |
| 659 | } |
| 660 | |
| 661 | |
| 662 | /* track caller id inside control connection, call expect_related */ |
| 663 | static int |
| 664 | conntrack_pptp_help(struct sk_buff **pskb, |
| 665 | struct ip_conntrack *ct, enum ip_conntrack_info ctinfo) |
| 666 | |
| 667 | { |
| 668 | struct pptp_pkt_hdr _pptph, *pptph; |
| 669 | struct tcphdr _tcph, *tcph; |
| 670 | u_int32_t tcplen = (*pskb)->len - (*pskb)->nh.iph->ihl * 4; |
| 671 | u_int32_t datalen; |
| 672 | int dir = CTINFO2DIR(ctinfo); |
| 673 | struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info; |
| 674 | unsigned int nexthdr_off; |
| 675 | |
| 676 | int oldsstate, oldcstate; |
| 677 | int ret; |
| 678 | |
| 679 | /* don't do any tracking before tcp handshake complete */ |
| 680 | if (ctinfo != IP_CT_ESTABLISHED |
| 681 | && ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) { |
| 682 | DEBUGP("ctinfo = %u, skipping\n", ctinfo); |
| 683 | return NF_ACCEPT; |
| 684 | } |
| 685 | |
| 686 | nexthdr_off = (*pskb)->nh.iph->ihl*4; |
| 687 | tcph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_tcph), &_tcph); |
| 688 | BUG_ON(!tcph); |
| 689 | nexthdr_off += tcph->doff * 4; |
| 690 | datalen = tcplen - tcph->doff * 4; |
| 691 | |
| 692 | if (tcph->fin || tcph->rst) { |
| 693 | DEBUGP("RST/FIN received, timeouting GRE\n"); |
| 694 | /* can't do this after real newnat */ |
| 695 | info->cstate = PPTP_CALL_NONE; |
| 696 | |
| 697 | /* untrack this call id, unexpect GRE packets */ |
| 698 | pptp_destroy_siblings(ct); |
| 699 | } |
| 700 | |
| 701 | pptph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_pptph), &_pptph); |
| 702 | if (!pptph) { |
| 703 | DEBUGP("no full PPTP header, can't track\n"); |
| 704 | return NF_ACCEPT; |
| 705 | } |
| 706 | nexthdr_off += sizeof(_pptph); |
| 707 | datalen -= sizeof(_pptph); |
| 708 | |
| 709 | /* if it's not a control message we can't do anything with it */ |
| 710 | if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL || |
| 711 | ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) { |
| 712 | DEBUGP("not a control packet\n"); |
| 713 | return NF_ACCEPT; |
| 714 | } |
| 715 | |
| 716 | oldsstate = info->sstate; |
| 717 | oldcstate = info->cstate; |
| 718 | |
| 719 | spin_lock_bh(&ip_pptp_lock); |
| 720 | |
| 721 | /* FIXME: We just blindly assume that the control connection is always |
| 722 | * established from PNS->PAC. However, RFC makes no guarantee */ |
| 723 | if (dir == IP_CT_DIR_ORIGINAL) |
| 724 | /* client -> server (PNS -> PAC) */ |
| 725 | ret = pptp_outbound_pkt(pskb, tcph, nexthdr_off, datalen, ct, |
| 726 | ctinfo); |
| 727 | else |
| 728 | /* server -> client (PAC -> PNS) */ |
| 729 | ret = pptp_inbound_pkt(pskb, tcph, nexthdr_off, datalen, ct, |
| 730 | ctinfo); |
| 731 | DEBUGP("sstate: %d->%d, cstate: %d->%d\n", |
| 732 | oldsstate, info->sstate, oldcstate, info->cstate); |
| 733 | spin_unlock_bh(&ip_pptp_lock); |
| 734 | |
| 735 | return ret; |
| 736 | } |
| 737 | |
| 738 | /* control protocol helper */ |
| 739 | static struct ip_conntrack_helper pptp = { |
| 740 | .list = { NULL, NULL }, |
| 741 | .name = "pptp", |
| 742 | .me = THIS_MODULE, |
| 743 | .max_expected = 2, |
| 744 | .timeout = 5 * 60, |
| 745 | .tuple = { .src = { .ip = 0, |
| 746 | .u = { .tcp = { .port = |
| 747 | __constant_htons(PPTP_CONTROL_PORT) } } |
| 748 | }, |
| 749 | .dst = { .ip = 0, |
| 750 | .u = { .all = 0 }, |
| 751 | .protonum = IPPROTO_TCP |
| 752 | } |
| 753 | }, |
| 754 | .mask = { .src = { .ip = 0, |
Alexey Dobriyan | 6749720 | 2005-09-22 23:45:24 -0700 | [diff] [blame] | 755 | .u = { .tcp = { .port = __constant_htons(0xffff) } } |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 756 | }, |
| 757 | .dst = { .ip = 0, |
| 758 | .u = { .all = 0 }, |
| 759 | .protonum = 0xff |
| 760 | } |
| 761 | }, |
| 762 | .help = conntrack_pptp_help |
| 763 | }; |
| 764 | |
David S. Miller | a776809 | 2006-01-11 15:39:14 -0800 | [diff] [blame] | 765 | extern void ip_ct_proto_gre_fini(void); |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 766 | extern int __init ip_ct_proto_gre_init(void); |
| 767 | |
| 768 | /* ip_conntrack_pptp initialization */ |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 769 | static int __init ip_conntrack_helper_pptp_init(void) |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 770 | { |
| 771 | int retcode; |
| 772 | |
| 773 | retcode = ip_ct_proto_gre_init(); |
| 774 | if (retcode < 0) |
| 775 | return retcode; |
| 776 | |
| 777 | DEBUGP(" registering helper\n"); |
| 778 | if ((retcode = ip_conntrack_helper_register(&pptp))) { |
| 779 | printk(KERN_ERR "Unable to register conntrack application " |
| 780 | "helper for pptp: %d\n", retcode); |
| 781 | ip_ct_proto_gre_fini(); |
| 782 | return retcode; |
| 783 | } |
| 784 | |
| 785 | printk("ip_conntrack_pptp version %s loaded\n", IP_CT_PPTP_VERSION); |
| 786 | return 0; |
| 787 | } |
| 788 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 789 | static void __exit ip_conntrack_helper_pptp_fini(void) |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 790 | { |
| 791 | ip_conntrack_helper_unregister(&pptp); |
| 792 | ip_ct_proto_gre_fini(); |
| 793 | printk("ip_conntrack_pptp version %s unloaded\n", IP_CT_PPTP_VERSION); |
| 794 | } |
| 795 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 796 | module_init(ip_conntrack_helper_pptp_init); |
| 797 | module_exit(ip_conntrack_helper_pptp_fini); |
Harald Welte | 926b50f | 2005-09-19 15:33:08 -0700 | [diff] [blame] | 798 | |
| 799 | EXPORT_SYMBOL(ip_nat_pptp_hook_outbound); |
| 800 | EXPORT_SYMBOL(ip_nat_pptp_hook_inbound); |
| 801 | EXPORT_SYMBOL(ip_nat_pptp_hook_exp_gre); |
| 802 | EXPORT_SYMBOL(ip_nat_pptp_hook_expectfn); |