1 /* $OpenBSD: ip_ipip.c,v 1.42 2008/11/26 16:08:17 henning Exp $ */ 2 /* 3 * The authors of this code are John Ioannidis (ji@tla.org), 4 * Angelos D. Keromytis (kermit@csd.uch.gr) and 5 * Niels Provos (provos@physnet.uni-hamburg.de). 6 * 7 * The original version of this code was written by John Ioannidis 8 * for BSD/OS in Athens, Greece, in November 1995. 9 * 10 * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996, 11 * by Angelos D. Keromytis. 12 * 13 * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis 14 * and Niels Provos. 15 * 16 * Additional features in 1999 by Angelos D. Keromytis. 17 * 18 * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis, 19 * Angelos D. Keromytis and Niels Provos. 20 * Copyright (c) 2001, Angelos D. Keromytis. 21 * 22 * Permission to use, copy, and modify this software with or without fee 23 * is hereby granted, provided that this entire notice is included in 24 * all copies of any software which is or includes a copy or 25 * modification of this software. 26 * You may use this code under the GNU public license if you so wish. Please 27 * contribute changes back to the authors under this freer than GPL license 28 * so that we may further the use of strong encryption without limitations to 29 * all. 30 * 31 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR 32 * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY 33 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE 34 * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR 35 * PURPOSE. 36 */ 37 38 /* 39 * IP-inside-IP processing 40 */ 41 42 #include "pf.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/mbuf.h> 47 #include <sys/socket.h> 48 #include <sys/sysctl.h> 49 50 #include <net/if.h> 51 #include <net/route.h> 52 #include <net/netisr.h> 53 #include <net/bpf.h> 54 55 #include <netinet/in.h> 56 #include <netinet/in_systm.h> 57 #include <netinet/ip.h> 58 #include <netinet/in_pcb.h> 59 #include <netinet/in_var.h> 60 #include <netinet/ip_var.h> 61 #include <netinet/ip_ecn.h> 62 63 #ifdef MROUTING 64 #include <netinet/ip_mroute.h> 65 #endif 66 67 #include <netinet/ip_ipsp.h> 68 #include <netinet/ip_ipip.h> 69 70 #include "bpfilter.h" 71 72 #if NPF > 0 73 #include <net/pfvar.h> 74 #endif 75 76 #ifdef ENCDEBUG 77 #define DPRINTF(x) if (encdebug) printf x 78 #else 79 #define DPRINTF(x) 80 #endif 81 82 /* 83 * We can control the acceptance of IP4 packets by altering the sysctl 84 * net.inet.ipip.allow value. Zero means drop them, all else is acceptance. 85 */ 86 int ipip_allow = 0; 87 88 struct ipipstat ipipstat; 89 90 #ifdef INET6 91 /* 92 * Really only a wrapper for ipip_input(), for use with IPv6. 93 */ 94 int 95 ip4_input6(struct mbuf **m, int *offp, int proto) 96 { 97 /* If we do not accept IP-in-IP explicitly, drop. */ 98 if (!ipip_allow && ((*m)->m_flags & (M_AUTH|M_CONF)) == 0) { 99 DPRINTF(("ip4_input6(): dropped due to policy\n")); 100 ipipstat.ipips_pdrops++; 101 m_freem(*m); 102 return IPPROTO_DONE; 103 } 104 105 ipip_input(*m, *offp, NULL); 106 return IPPROTO_DONE; 107 } 108 #endif /* INET6 */ 109 110 #ifdef INET 111 /* 112 * Really only a wrapper for ipip_input(), for use with IPv4. 113 */ 114 void 115 ip4_input(struct mbuf *m, ...) 116 { 117 va_list ap; 118 int iphlen; 119 120 /* If we do not accept IP-in-IP explicitly, drop. */ 121 if (!ipip_allow && (m->m_flags & (M_AUTH|M_CONF)) == 0) { 122 DPRINTF(("ip4_input(): dropped due to policy\n")); 123 ipipstat.ipips_pdrops++; 124 m_freem(m); 125 return; 126 } 127 128 va_start(ap, m); 129 iphlen = va_arg(ap, int); 130 va_end(ap); 131 132 ipip_input(m, iphlen, NULL); 133 } 134 #endif /* INET */ 135 136 /* 137 * ipip_input gets called when we receive an IP{46} encapsulated packet, 138 * either because we got it at a real interface, or because AH or ESP 139 * were being used in tunnel mode (in which case the rcvif element will 140 * contain the address of the encX interface associated with the tunnel. 141 */ 142 143 void 144 ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp) 145 { 146 struct sockaddr_in *sin; 147 struct ifnet *ifp; 148 struct ifaddr *ifa; 149 struct ifqueue *ifq = NULL; 150 struct ip *ipo; 151 #ifdef INET6 152 struct sockaddr_in6 *sin6; 153 struct ip6_hdr *ip6 = NULL; 154 u_int8_t itos; 155 #endif 156 u_int8_t nxt; 157 int isr; 158 u_int8_t otos; 159 u_int8_t v; 160 int hlen, s; 161 162 ipipstat.ipips_ipackets++; 163 164 m_copydata(m, 0, 1, &v); 165 166 switch (v >> 4) { 167 #ifdef INET 168 case 4: 169 hlen = sizeof(struct ip); 170 break; 171 #endif /* INET */ 172 #ifdef INET6 173 case 6: 174 hlen = sizeof(struct ip6_hdr); 175 break; 176 #endif 177 default: 178 ipipstat.ipips_family++; 179 m_freem(m); 180 return /* EAFNOSUPPORT */; 181 } 182 183 /* Bring the IP header in the first mbuf, if not there already */ 184 if (m->m_len < hlen) { 185 if ((m = m_pullup(m, hlen)) == NULL) { 186 DPRINTF(("ipip_input(): m_pullup() failed\n")); 187 ipipstat.ipips_hdrops++; 188 return; 189 } 190 } 191 192 ipo = mtod(m, struct ip *); 193 194 /* Keep outer ecn field. */ 195 switch (v >> 4) { 196 #ifdef INET 197 case 4: 198 otos = ipo->ip_tos; 199 break; 200 #endif /* INET */ 201 #ifdef INET6 202 case 6: 203 otos = (ntohl(mtod(m, struct ip6_hdr *)->ip6_flow) >> 20) & 0xff; 204 break; 205 #endif 206 default: 207 panic("ipip_input: should never reach here"); 208 } 209 210 /* Remove outer IP header */ 211 m_adj(m, iphlen); 212 213 /* Sanity check */ 214 if (m->m_pkthdr.len < sizeof(struct ip)) { 215 ipipstat.ipips_hdrops++; 216 m_freem(m); 217 return; 218 } 219 220 m_copydata(m, 0, 1, &v); 221 222 switch (v >> 4) { 223 #ifdef INET 224 case 4: 225 hlen = sizeof(struct ip); 226 break; 227 #endif /* INET */ 228 229 #ifdef INET6 230 case 6: 231 hlen = sizeof(struct ip6_hdr); 232 break; 233 #endif 234 default: 235 ipipstat.ipips_family++; 236 m_freem(m); 237 return; /* EAFNOSUPPORT */ 238 } 239 240 /* 241 * Bring the inner IP header in the first mbuf, if not there already. 242 */ 243 if (m->m_len < hlen) { 244 if ((m = m_pullup(m, hlen)) == NULL) { 245 DPRINTF(("ipip_input(): m_pullup() failed\n")); 246 ipipstat.ipips_hdrops++; 247 return; 248 } 249 } 250 251 /* 252 * RFC 1853 specifies that the inner TTL should not be touched on 253 * decapsulation. There's no reason this comment should be here, but 254 * this is as good as any a position. 255 */ 256 257 /* Some sanity checks in the inner IP header */ 258 switch (v >> 4) { 259 #ifdef INET 260 case 4: 261 ipo = mtod(m, struct ip *); 262 nxt = ipo->ip_p; 263 if (!ip_ecn_egress(ECN_ALLOWED, &otos, &ipo->ip_tos)) { 264 m_freem(m); 265 return; 266 } 267 break; 268 #endif /* INET */ 269 #ifdef INET6 270 case 6: 271 ip6 = (struct ip6_hdr *) ipo; 272 nxt = ip6->ip6_nxt; 273 itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 274 if (!ip_ecn_egress(ECN_ALLOWED, &otos, &itos)) { 275 m_freem(m); 276 return; 277 } 278 ip6->ip6_flow &= ~htonl(0xff << 20); 279 ip6->ip6_flow |= htonl((u_int32_t) itos << 20); 280 break; 281 #endif 282 default: 283 panic("ipip_input: should never reach here"); 284 } 285 286 /* Check for local address spoofing. */ 287 if ((m->m_pkthdr.rcvif == NULL || 288 !(m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK)) && 289 ipip_allow != 2) { 290 TAILQ_FOREACH(ifp, &ifnet, if_list) { 291 TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list) { 292 #ifdef INET 293 if (ipo) { 294 if (ifa->ifa_addr->sa_family != 295 AF_INET) 296 continue; 297 298 sin = (struct sockaddr_in *) ifa->ifa_addr; 299 300 if (sin->sin_addr.s_addr == 301 ipo->ip_src.s_addr) { 302 ipipstat.ipips_spoof++; 303 m_freem(m); 304 return; 305 } 306 } 307 #endif /* INET */ 308 309 #ifdef INET6 310 if (ip6) { 311 if (ifa->ifa_addr->sa_family != 312 AF_INET6) 313 continue; 314 315 sin6 = (struct sockaddr_in6 *) ifa->ifa_addr; 316 317 if (IN6_ARE_ADDR_EQUAL(&sin6->sin6_addr, &ip6->ip6_src)) { 318 ipipstat.ipips_spoof++; 319 m_freem(m); 320 return; 321 } 322 323 } 324 #endif /* INET6 */ 325 } 326 } 327 } 328 329 /* Statistics */ 330 ipipstat.ipips_ibytes += m->m_pkthdr.len - iphlen; 331 332 /* 333 * Interface pointer stays the same; if no IPsec processing has 334 * been done (or will be done), this will point to a normal 335 * interface. Otherwise, it'll point to an enc interface, which 336 * will allow a packet filter to distinguish between secure and 337 * untrusted packets. 338 */ 339 340 switch (v >> 4) { 341 #ifdef INET 342 case 4: 343 ifq = &ipintrq; 344 isr = NETISR_IP; 345 break; 346 #endif 347 #ifdef INET6 348 case 6: 349 ifq = &ip6intrq; 350 isr = NETISR_IPV6; 351 break; 352 #endif 353 default: 354 panic("ipip_input: should never reach here"); 355 } 356 357 #if NBPFILTER > 0 358 if (gifp && gifp->if_bpf) 359 bpf_mtap_af(gifp->if_bpf, ifq == &ipintrq ? AF_INET : AF_INET6, 360 m, BPF_DIRECTION_IN); 361 #endif 362 #if NPF > 0 363 pf_pkt_addr_changed(m); 364 #endif 365 366 s = splnet(); /* isn't it already? */ 367 if (IF_QFULL(ifq)) { 368 IF_DROP(ifq); 369 m_freem(m); 370 ipipstat.ipips_qfull++; 371 372 splx(s); 373 374 DPRINTF(("ipip_input(): packet dropped because of full " 375 "queue\n")); 376 return; 377 } 378 379 IF_ENQUEUE(ifq, m); 380 schednetisr(isr); 381 splx(s); 382 return; 383 } 384 385 int 386 ipip_output(struct mbuf *m, struct tdb *tdb, struct mbuf **mp, int dummy, 387 int dummy2) 388 { 389 u_int8_t tp, otos; 390 391 #ifdef INET 392 u_int8_t itos; 393 struct ip *ipo; 394 #endif /* INET */ 395 396 #ifdef INET6 397 struct ip6_hdr *ip6, *ip6o; 398 #endif /* INET6 */ 399 400 /* XXX Deal with empty TDB source/destination addresses. */ 401 402 m_copydata(m, 0, 1, &tp); 403 tp = (tp >> 4) & 0xff; /* Get the IP version number. */ 404 405 switch (tdb->tdb_dst.sa.sa_family) { 406 #ifdef INET 407 case AF_INET: 408 if (tdb->tdb_src.sa.sa_family != AF_INET || 409 tdb->tdb_src.sin.sin_addr.s_addr == INADDR_ANY || 410 tdb->tdb_dst.sin.sin_addr.s_addr == INADDR_ANY) { 411 412 DPRINTF(("ipip_output(): unspecified tunnel endpoind " 413 "address in SA %s/%08x\n", 414 ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi))); 415 416 ipipstat.ipips_unspec++; 417 m_freem(m); 418 *mp = NULL; 419 return EINVAL; 420 } 421 422 M_PREPEND(m, sizeof(struct ip), M_DONTWAIT); 423 if (m == 0) { 424 DPRINTF(("ipip_output(): M_PREPEND failed\n")); 425 ipipstat.ipips_hdrops++; 426 *mp = NULL; 427 return ENOBUFS; 428 } 429 430 ipo = mtod(m, struct ip *); 431 432 ipo->ip_v = IPVERSION; 433 ipo->ip_hl = 5; 434 ipo->ip_len = htons(m->m_pkthdr.len); 435 ipo->ip_ttl = ip_defttl; 436 ipo->ip_sum = 0; 437 ipo->ip_src = tdb->tdb_src.sin.sin_addr; 438 ipo->ip_dst = tdb->tdb_dst.sin.sin_addr; 439 440 /* 441 * We do the htons() to prevent snoopers from determining our 442 * endianness. 443 */ 444 ipo->ip_id = htons(ip_randomid()); 445 446 /* If the inner protocol is IP... */ 447 if (tp == IPVERSION) { 448 /* Save ECN notification */ 449 m_copydata(m, sizeof(struct ip) + 450 offsetof(struct ip, ip_tos), 451 sizeof(u_int8_t), (caddr_t) &itos); 452 453 ipo->ip_p = IPPROTO_IPIP; 454 455 /* 456 * We should be keeping tunnel soft-state and 457 * send back ICMPs if needed. 458 */ 459 m_copydata(m, sizeof(struct ip) + 460 offsetof(struct ip, ip_off), 461 sizeof(u_int16_t), (caddr_t) &ipo->ip_off); 462 NTOHS(ipo->ip_off); 463 ipo->ip_off &= ~(IP_DF | IP_MF | IP_OFFMASK); 464 HTONS(ipo->ip_off); 465 } 466 #ifdef INET6 467 else if (tp == (IPV6_VERSION >> 4)) { 468 u_int32_t itos32; 469 470 /* Save ECN notification. */ 471 m_copydata(m, sizeof(struct ip) + 472 offsetof(struct ip6_hdr, ip6_flow), 473 sizeof(u_int32_t), (caddr_t) &itos32); 474 itos = ntohl(itos32) >> 20; 475 ipo->ip_p = IPPROTO_IPV6; 476 ipo->ip_off = 0; 477 } 478 #endif /* INET6 */ 479 else { 480 m_freem(m); 481 *mp = NULL; 482 ipipstat.ipips_family++; 483 return EAFNOSUPPORT; 484 } 485 486 otos = 0; 487 ip_ecn_ingress(ECN_ALLOWED, &otos, &itos); 488 ipo->ip_tos = otos; 489 break; 490 #endif /* INET */ 491 492 #ifdef INET6 493 case AF_INET6: 494 if (IN6_IS_ADDR_UNSPECIFIED(&tdb->tdb_dst.sin6.sin6_addr) || 495 tdb->tdb_src.sa.sa_family != AF_INET6 || 496 IN6_IS_ADDR_UNSPECIFIED(&tdb->tdb_src.sin6.sin6_addr)) { 497 498 DPRINTF(("ipip_output(): unspecified tunnel endpoind " 499 "address in SA %s/%08x\n", 500 ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi))); 501 502 ipipstat.ipips_unspec++; 503 m_freem(m); 504 *mp = NULL; 505 return ENOBUFS; 506 } 507 508 /* If the inner protocol is IPv6, clear link local scope */ 509 if (tp == (IPV6_VERSION >> 4)) { 510 /* scoped address handling */ 511 ip6 = mtod(m, struct ip6_hdr *); 512 if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) 513 ip6->ip6_src.s6_addr16[1] = 0; 514 if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) 515 ip6->ip6_dst.s6_addr16[1] = 0; 516 } 517 518 M_PREPEND(m, sizeof(struct ip6_hdr), M_DONTWAIT); 519 if (m == 0) { 520 DPRINTF(("ipip_output(): M_PREPEND failed\n")); 521 ipipstat.ipips_hdrops++; 522 *mp = NULL; 523 return ENOBUFS; 524 } 525 526 /* Initialize IPv6 header */ 527 ip6o = mtod(m, struct ip6_hdr *); 528 ip6o->ip6_flow = 0; 529 ip6o->ip6_vfc &= ~IPV6_VERSION_MASK; 530 ip6o->ip6_vfc |= IPV6_VERSION; 531 ip6o->ip6_plen = htons(m->m_pkthdr.len - sizeof(*ip6o)); 532 ip6o->ip6_hlim = ip_defttl; 533 in6_embedscope(&ip6o->ip6_src, &tdb->tdb_src.sin6, NULL, NULL); 534 in6_embedscope(&ip6o->ip6_dst, &tdb->tdb_dst.sin6, NULL, NULL); 535 536 #ifdef INET 537 if (tp == IPVERSION) { 538 /* Save ECN notification */ 539 m_copydata(m, sizeof(struct ip6_hdr) + 540 offsetof(struct ip, ip_tos), sizeof(u_int8_t), 541 (caddr_t) &itos); 542 543 /* This is really IPVERSION. */ 544 ip6o->ip6_nxt = IPPROTO_IPIP; 545 } 546 else 547 #endif /* INET */ 548 if (tp == (IPV6_VERSION >> 4)) { 549 u_int32_t itos32; 550 551 /* Save ECN notification. */ 552 m_copydata(m, sizeof(struct ip6_hdr) + 553 offsetof(struct ip6_hdr, ip6_flow), 554 sizeof(u_int32_t), (caddr_t) &itos32); 555 itos = ntohl(itos32) >> 20; 556 557 ip6o->ip6_nxt = IPPROTO_IPV6; 558 } else { 559 m_freem(m); 560 *mp = NULL; 561 ipipstat.ipips_family++; 562 return EAFNOSUPPORT; 563 } 564 565 otos = 0; 566 ip_ecn_ingress(ECN_ALLOWED, &otos, &itos); 567 ip6o->ip6_flow |= htonl((u_int32_t) otos << 20); 568 break; 569 #endif /* INET6 */ 570 571 default: 572 DPRINTF(("ipip_output(): unsupported protocol family %d\n", 573 tdb->tdb_dst.sa.sa_family)); 574 m_freem(m); 575 *mp = NULL; 576 ipipstat.ipips_family++; 577 return EAFNOSUPPORT; 578 } 579 580 ipipstat.ipips_opackets++; 581 *mp = m; 582 583 #ifdef INET 584 if (tdb->tdb_dst.sa.sa_family == AF_INET) { 585 if (tdb->tdb_xform->xf_type == XF_IP4) 586 tdb->tdb_cur_bytes += 587 m->m_pkthdr.len - sizeof(struct ip); 588 589 ipipstat.ipips_obytes += m->m_pkthdr.len - sizeof(struct ip); 590 } 591 #endif /* INET */ 592 593 #ifdef INET6 594 if (tdb->tdb_dst.sa.sa_family == AF_INET6) { 595 if (tdb->tdb_xform->xf_type == XF_IP4) 596 tdb->tdb_cur_bytes += 597 m->m_pkthdr.len - sizeof(struct ip6_hdr); 598 599 ipipstat.ipips_obytes += 600 m->m_pkthdr.len - sizeof(struct ip6_hdr); 601 } 602 #endif /* INET6 */ 603 604 return 0; 605 } 606 607 #ifdef IPSEC 608 int 609 ipe4_attach() 610 { 611 return 0; 612 } 613 614 int 615 ipe4_init(struct tdb *tdbp, struct xformsw *xsp, struct ipsecinit *ii) 616 { 617 tdbp->tdb_xform = xsp; 618 return 0; 619 } 620 621 int 622 ipe4_zeroize(struct tdb *tdbp) 623 { 624 return 0; 625 } 626 627 void 628 ipe4_input(struct mbuf *m, ...) 629 { 630 /* This is a rather serious mistake, so no conditional printing. */ 631 printf("ipe4_input(): should never be called\n"); 632 if (m) 633 m_freem(m); 634 } 635 #endif /* IPSEC */ 636 637 int 638 ipip_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp, 639 size_t newlen) 640 { 641 /* All sysctl names at this level are terminal. */ 642 if (namelen != 1) 643 return (ENOTDIR); 644 645 switch (name[0]) { 646 case IPIPCTL_ALLOW: 647 return (sysctl_int(oldp, oldlenp, newp, newlen, &ipip_allow)); 648 case IPIPCTL_STATS: 649 if (newp != NULL) 650 return (EPERM); 651 return (sysctl_struct(oldp, oldlenp, newp, newlen, 652 &ipipstat, sizeof(ipipstat))); 653 default: 654 return (ENOPROTOOPT); 655 } 656 /* NOTREACHED */ 657 } 658