1 /* $OpenBSD: ip_ipip.c,v 1.89 2018/11/14 23:55:04 dlg 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 "bpfilter.h" 43 #include "gif.h" 44 #include "pf.h" 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/mbuf.h> 49 #include <sys/socket.h> 50 #include <sys/sysctl.h> 51 52 #include <net/if.h> 53 #include <net/if_types.h> 54 #include <net/if_var.h> 55 #include <net/route.h> 56 #include <net/netisr.h> 57 #include <net/bpf.h> 58 59 #include <netinet/in.h> 60 #include <netinet/ip.h> 61 #include <netinet/in_pcb.h> 62 #include <netinet/ip_var.h> 63 #include <netinet/ip_ecn.h> 64 #include <netinet/ip_ipip.h> 65 66 #ifdef MROUTING 67 #include <netinet/ip_mroute.h> 68 #endif 69 70 #if NPF > 0 71 #include <net/pfvar.h> 72 #endif 73 74 #ifdef ENCDEBUG 75 #define DPRINTF(x) if (encdebug) printf x 76 #else 77 #define DPRINTF(x) 78 #endif 79 80 /* 81 * We can control the acceptance of IP4 packets by altering the sysctl 82 * net.inet.ipip.allow value. Zero means drop them, all else is acceptance. 83 */ 84 int ipip_allow = 0; 85 86 struct cpumem *ipipcounters; 87 88 void 89 ipip_init(void) 90 { 91 ipipcounters = counters_alloc(ipips_ncounters); 92 } 93 94 /* 95 * Really only a wrapper for ipip_input_if(), for use with pr_input. 96 */ 97 int 98 ipip_input(struct mbuf **mp, int *offp, int nxt, int af) 99 { 100 struct ifnet *ifp; 101 102 /* If we do not accept IP-in-IP explicitly, drop. */ 103 if (!ipip_allow && ((*mp)->m_flags & (M_AUTH|M_CONF)) == 0) { 104 DPRINTF(("%s: dropped due to policy\n", __func__)); 105 ipipstat_inc(ipips_pdrops); 106 m_freemp(mp); 107 return IPPROTO_DONE; 108 } 109 110 ifp = if_get((*mp)->m_pkthdr.ph_ifidx); 111 if (ifp == NULL) { 112 m_freemp(mp); 113 return IPPROTO_DONE; 114 } 115 nxt = ipip_input_if(mp, offp, nxt, af, ifp); 116 if_put(ifp); 117 118 return nxt; 119 } 120 121 /* 122 * ipip_input gets called when we receive an IP{46} encapsulated packet, 123 * either because we got it at a real interface, or because AH or ESP 124 * were being used in tunnel mode (in which case the ph_ifidx element 125 * will contain the index of the encX interface associated with the 126 * tunnel. 127 */ 128 129 int 130 ipip_input_if(struct mbuf **mp, int *offp, int proto, int oaf, 131 struct ifnet *ifp) 132 { 133 struct mbuf *m = *mp; 134 struct sockaddr_in *sin; 135 struct ip *ip; 136 #ifdef INET6 137 struct sockaddr_in6 *sin6; 138 struct ip6_hdr *ip6; 139 #endif 140 int mode, hlen; 141 u_int8_t itos, otos; 142 sa_family_t iaf; 143 144 ipipstat_inc(ipips_ipackets); 145 146 switch (oaf) { 147 case AF_INET: 148 hlen = sizeof(struct ip); 149 break; 150 #ifdef INET6 151 case AF_INET6: 152 hlen = sizeof(struct ip6_hdr); 153 break; 154 #endif 155 default: 156 unhandled_af(oaf); 157 } 158 159 /* Bring the IP header in the first mbuf, if not there already */ 160 if (m->m_len < hlen) { 161 if ((m = *mp = m_pullup(m, hlen)) == NULL) { 162 DPRINTF(("%s: m_pullup() failed\n", __func__)); 163 ipipstat_inc(ipips_hdrops); 164 goto bad; 165 } 166 } 167 168 /* Keep outer ecn field. */ 169 switch (oaf) { 170 case AF_INET: 171 ip = mtod(m, struct ip *); 172 otos = ip->ip_tos; 173 break; 174 #ifdef INET6 175 case AF_INET6: 176 ip6 = mtod(m, struct ip6_hdr *); 177 otos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 178 break; 179 #endif 180 } 181 182 /* Remove outer IP header */ 183 KASSERT(*offp > 0); 184 m_adj(m, *offp); 185 *offp = 0; 186 ip = NULL; 187 #ifdef INET6 188 ip6 = NULL; 189 #endif 190 191 switch (proto) { 192 case IPPROTO_IPV4: 193 hlen = sizeof(struct ip); 194 break; 195 196 #ifdef INET6 197 case IPPROTO_IPV6: 198 hlen = sizeof(struct ip6_hdr); 199 break; 200 #endif 201 default: 202 ipipstat_inc(ipips_family); 203 goto bad; 204 } 205 206 /* Sanity check */ 207 if (m->m_pkthdr.len < hlen) { 208 ipipstat_inc(ipips_hdrops); 209 goto bad; 210 } 211 212 /* 213 * Bring the inner header into the first mbuf, if not there already. 214 */ 215 if (m->m_len < hlen) { 216 if ((m = *mp = m_pullup(m, hlen)) == NULL) { 217 DPRINTF(("%s: m_pullup() failed\n", __func__)); 218 ipipstat_inc(ipips_hdrops); 219 goto bad; 220 } 221 } 222 223 /* 224 * RFC 1853 specifies that the inner TTL should not be touched on 225 * decapsulation. There's no reason this comment should be here, but 226 * this is as good as any a position. 227 */ 228 229 /* Some sanity checks in the inner IP header */ 230 switch (proto) { 231 case IPPROTO_IPV4: 232 iaf = AF_INET; 233 ip = mtod(m, struct ip *); 234 hlen = ip->ip_hl << 2; 235 if (m->m_pkthdr.len < hlen) { 236 ipipstat_inc(ipips_hdrops); 237 goto bad; 238 } 239 itos = ip->ip_tos; 240 mode = m->m_flags & (M_AUTH|M_CONF) ? 241 ECN_ALLOWED_IPSEC : ECN_ALLOWED; 242 if (!ip_ecn_egress(mode, &otos, &itos)) { 243 DPRINTF(("%s: ip_ecn_egress() failed\n", __func__)); 244 ipipstat_inc(ipips_pdrops); 245 goto bad; 246 } 247 /* re-calculate the checksum if ip_tos was changed */ 248 if (itos != ip->ip_tos) 249 ip_tos_patch(ip, itos); 250 break; 251 #ifdef INET6 252 case IPPROTO_IPV6: 253 iaf = AF_INET6; 254 ip6 = mtod(m, struct ip6_hdr *); 255 itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 256 if (!ip_ecn_egress(ECN_ALLOWED, &otos, &itos)) { 257 DPRINTF(("%s: ip_ecn_egress() failed\n", __func__)); 258 ipipstat_inc(ipips_pdrops); 259 goto bad; 260 } 261 ip6->ip6_flow &= ~htonl(0xff << 20); 262 ip6->ip6_flow |= htonl((u_int32_t) itos << 20); 263 break; 264 #endif 265 } 266 267 /* Check for local address spoofing. */ 268 if (!(ifp->if_flags & IFF_LOOPBACK) && ipip_allow != 2) { 269 struct sockaddr_storage ss; 270 struct rtentry *rt; 271 272 memset(&ss, 0, sizeof(ss)); 273 274 if (ip) { 275 sin = (struct sockaddr_in *)&ss; 276 sin->sin_family = AF_INET; 277 sin->sin_len = sizeof(*sin); 278 sin->sin_addr = ip->ip_src; 279 #ifdef INET6 280 } else if (ip6) { 281 sin6 = (struct sockaddr_in6 *)&ss; 282 sin6->sin6_family = AF_INET6; 283 sin6->sin6_len = sizeof(*sin6); 284 sin6->sin6_addr = ip6->ip6_src; 285 #endif /* INET6 */ 286 } 287 rt = rtalloc(sstosa(&ss), 0, m->m_pkthdr.ph_rtableid); 288 if ((rt != NULL) && (rt->rt_flags & RTF_LOCAL)) { 289 ipipstat_inc(ipips_spoof); 290 rtfree(rt); 291 goto bad; 292 } 293 rtfree(rt); 294 } 295 296 /* Statistics */ 297 ipipstat_add(ipips_ibytes, m->m_pkthdr.len - hlen); 298 299 #if NBPFILTER > 0 && NGIF > 0 300 if (ifp->if_type == IFT_GIF && ifp->if_bpf != NULL) 301 bpf_mtap_af(ifp->if_bpf, iaf, m, BPF_DIRECTION_IN); 302 #endif 303 #if NPF > 0 304 pf_pkt_addr_changed(m); 305 #endif 306 307 /* 308 * Interface pointer stays the same; if no IPsec processing has 309 * been done (or will be done), this will point to a normal 310 * interface. Otherwise, it'll point to an enc interface, which 311 * will allow a packet filter to distinguish between secure and 312 * untrusted packets. 313 */ 314 315 switch (proto) { 316 case IPPROTO_IPV4: 317 return ip_input_if(mp, offp, proto, oaf, ifp); 318 #ifdef INET6 319 case IPPROTO_IPV6: 320 return ip6_input_if(mp, offp, proto, oaf, ifp); 321 #endif 322 } 323 bad: 324 m_freemp(mp); 325 return IPPROTO_DONE; 326 } 327 328 int 329 ipip_output(struct mbuf *m, struct tdb *tdb, struct mbuf **mp, int dummy, 330 int dummy2) 331 { 332 u_int8_t tp, otos, itos; 333 u_int64_t obytes; 334 struct ip *ipo; 335 #ifdef INET6 336 struct ip6_hdr *ip6, *ip6o; 337 #endif /* INET6 */ 338 #ifdef ENCDEBUG 339 char buf[INET6_ADDRSTRLEN]; 340 #endif 341 342 /* XXX Deal with empty TDB source/destination addresses. */ 343 344 m_copydata(m, 0, 1, &tp); 345 tp = (tp >> 4) & 0xff; /* Get the IP version number. */ 346 347 switch (tdb->tdb_dst.sa.sa_family) { 348 case AF_INET: 349 if (tdb->tdb_src.sa.sa_family != AF_INET || 350 tdb->tdb_src.sin.sin_addr.s_addr == INADDR_ANY || 351 tdb->tdb_dst.sin.sin_addr.s_addr == INADDR_ANY) { 352 353 DPRINTF(("%s: unspecified tunnel endpoind " 354 "address in SA %s/%08x\n", __func__, 355 ipsp_address(&tdb->tdb_dst, buf, sizeof(buf)), 356 ntohl(tdb->tdb_spi))); 357 358 ipipstat_inc(ipips_unspec); 359 m_freem(m); 360 *mp = NULL; 361 return EINVAL; 362 } 363 364 M_PREPEND(m, sizeof(struct ip), M_DONTWAIT); 365 if (m == NULL) { 366 DPRINTF(("%s: M_PREPEND failed\n", __func__)); 367 ipipstat_inc(ipips_hdrops); 368 *mp = NULL; 369 return ENOBUFS; 370 } 371 372 ipo = mtod(m, struct ip *); 373 374 ipo->ip_v = IPVERSION; 375 ipo->ip_hl = 5; 376 ipo->ip_len = htons(m->m_pkthdr.len); 377 ipo->ip_ttl = ip_defttl; 378 ipo->ip_sum = 0; 379 ipo->ip_src = tdb->tdb_src.sin.sin_addr; 380 ipo->ip_dst = tdb->tdb_dst.sin.sin_addr; 381 382 /* 383 * We do the htons() to prevent snoopers from determining our 384 * endianness. 385 */ 386 ipo->ip_id = htons(ip_randomid()); 387 388 /* If the inner protocol is IP... */ 389 if (tp == IPVERSION) { 390 /* Save ECN notification */ 391 m_copydata(m, sizeof(struct ip) + 392 offsetof(struct ip, ip_tos), 393 sizeof(u_int8_t), (caddr_t) &itos); 394 395 ipo->ip_p = IPPROTO_IPIP; 396 397 /* 398 * We should be keeping tunnel soft-state and 399 * send back ICMPs if needed. 400 */ 401 m_copydata(m, sizeof(struct ip) + 402 offsetof(struct ip, ip_off), 403 sizeof(u_int16_t), (caddr_t) &ipo->ip_off); 404 ipo->ip_off = ntohs(ipo->ip_off); 405 ipo->ip_off &= ~(IP_DF | IP_MF | IP_OFFMASK); 406 ipo->ip_off = htons(ipo->ip_off); 407 } 408 #ifdef INET6 409 else if (tp == (IPV6_VERSION >> 4)) { 410 u_int32_t itos32; 411 412 /* Save ECN notification. */ 413 m_copydata(m, sizeof(struct ip) + 414 offsetof(struct ip6_hdr, ip6_flow), 415 sizeof(u_int32_t), (caddr_t) &itos32); 416 itos = ntohl(itos32) >> 20; 417 ipo->ip_p = IPPROTO_IPV6; 418 ipo->ip_off = 0; 419 } 420 #endif /* INET6 */ 421 else { 422 m_freem(m); 423 *mp = NULL; 424 ipipstat_inc(ipips_family); 425 return EAFNOSUPPORT; 426 } 427 428 otos = 0; 429 ip_ecn_ingress(ECN_ALLOWED, &otos, &itos); 430 ipo->ip_tos = otos; 431 break; 432 433 #ifdef INET6 434 case AF_INET6: 435 if (IN6_IS_ADDR_UNSPECIFIED(&tdb->tdb_dst.sin6.sin6_addr) || 436 tdb->tdb_src.sa.sa_family != AF_INET6 || 437 IN6_IS_ADDR_UNSPECIFIED(&tdb->tdb_src.sin6.sin6_addr)) { 438 439 DPRINTF(("%s: unspecified tunnel endpoind " 440 "address in SA %s/%08x\n", __func__, 441 ipsp_address(&tdb->tdb_dst, buf, sizeof(buf)), 442 ntohl(tdb->tdb_spi))); 443 444 ipipstat_inc(ipips_unspec); 445 m_freem(m); 446 *mp = NULL; 447 return ENOBUFS; 448 } 449 450 /* If the inner protocol is IPv6, clear link local scope */ 451 if (tp == (IPV6_VERSION >> 4)) { 452 /* scoped address handling */ 453 ip6 = mtod(m, struct ip6_hdr *); 454 if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) 455 ip6->ip6_src.s6_addr16[1] = 0; 456 if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) 457 ip6->ip6_dst.s6_addr16[1] = 0; 458 } 459 460 M_PREPEND(m, sizeof(struct ip6_hdr), M_DONTWAIT); 461 if (m == NULL) { 462 DPRINTF(("%s: M_PREPEND failed\n", __func__)); 463 ipipstat_inc(ipips_hdrops); 464 *mp = NULL; 465 return ENOBUFS; 466 } 467 468 /* Initialize IPv6 header */ 469 ip6o = mtod(m, struct ip6_hdr *); 470 ip6o->ip6_flow = 0; 471 ip6o->ip6_vfc &= ~IPV6_VERSION_MASK; 472 ip6o->ip6_vfc |= IPV6_VERSION; 473 ip6o->ip6_plen = htons(m->m_pkthdr.len - sizeof(*ip6o)); 474 ip6o->ip6_hlim = ip_defttl; 475 in6_embedscope(&ip6o->ip6_src, &tdb->tdb_src.sin6, NULL); 476 in6_embedscope(&ip6o->ip6_dst, &tdb->tdb_dst.sin6, NULL); 477 478 if (tp == IPVERSION) { 479 /* Save ECN notification */ 480 m_copydata(m, sizeof(struct ip6_hdr) + 481 offsetof(struct ip, ip_tos), sizeof(u_int8_t), 482 (caddr_t) &itos); 483 484 /* This is really IPVERSION. */ 485 ip6o->ip6_nxt = IPPROTO_IPIP; 486 } 487 else 488 if (tp == (IPV6_VERSION >> 4)) { 489 u_int32_t itos32; 490 491 /* Save ECN notification. */ 492 m_copydata(m, sizeof(struct ip6_hdr) + 493 offsetof(struct ip6_hdr, ip6_flow), 494 sizeof(u_int32_t), (caddr_t) &itos32); 495 itos = ntohl(itos32) >> 20; 496 497 ip6o->ip6_nxt = IPPROTO_IPV6; 498 } else { 499 m_freem(m); 500 *mp = NULL; 501 ipipstat_inc(ipips_family); 502 return EAFNOSUPPORT; 503 } 504 505 otos = 0; 506 ip_ecn_ingress(ECN_ALLOWED, &otos, &itos); 507 ip6o->ip6_flow |= htonl((u_int32_t) otos << 20); 508 break; 509 #endif /* INET6 */ 510 511 default: 512 DPRINTF(("%s: unsupported protocol family %d\n", __func__, 513 tdb->tdb_dst.sa.sa_family)); 514 m_freem(m); 515 *mp = NULL; 516 ipipstat_inc(ipips_family); 517 return EAFNOSUPPORT; 518 } 519 520 ipipstat_inc(ipips_opackets); 521 *mp = m; 522 523 if (tdb->tdb_dst.sa.sa_family == AF_INET) { 524 obytes = m->m_pkthdr.len - sizeof(struct ip); 525 if (tdb->tdb_xform->xf_type == XF_IP4) 526 tdb->tdb_cur_bytes += obytes; 527 528 ipipstat_add(ipips_obytes, obytes); 529 } 530 531 #ifdef INET6 532 if (tdb->tdb_dst.sa.sa_family == AF_INET6) { 533 obytes = m->m_pkthdr.len - sizeof(struct ip6_hdr); 534 if (tdb->tdb_xform->xf_type == XF_IP4) 535 tdb->tdb_cur_bytes += obytes; 536 537 ipipstat_add(ipips_obytes, obytes); 538 } 539 #endif /* INET6 */ 540 541 return 0; 542 } 543 544 #ifdef IPSEC 545 int 546 ipe4_attach(void) 547 { 548 return 0; 549 } 550 551 int 552 ipe4_init(struct tdb *tdbp, struct xformsw *xsp, struct ipsecinit *ii) 553 { 554 tdbp->tdb_xform = xsp; 555 return 0; 556 } 557 558 int 559 ipe4_zeroize(struct tdb *tdbp) 560 { 561 return 0; 562 } 563 564 int 565 ipe4_input(struct mbuf *m, struct tdb *tdb, int hlen, int proto) 566 { 567 /* This is a rather serious mistake, so no conditional printing. */ 568 printf("ipe4_input(): should never be called\n"); 569 m_freem(m); 570 return EINVAL; 571 } 572 #endif /* IPSEC */ 573 574 int 575 ipip_sysctl_ipipstat(void *oldp, size_t *oldlenp, void *newp) 576 { 577 struct ipipstat ipipstat; 578 579 CTASSERT(sizeof(ipipstat) == (ipips_ncounters * sizeof(uint64_t))); 580 memset(&ipipstat, 0, sizeof ipipstat); 581 counters_read(ipipcounters, (uint64_t *)&ipipstat, ipips_ncounters); 582 return (sysctl_rdstruct(oldp, oldlenp, newp, 583 &ipipstat, sizeof(ipipstat))); 584 } 585 586 int 587 ipip_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp, 588 size_t newlen) 589 { 590 int error; 591 592 /* All sysctl names at this level are terminal. */ 593 if (namelen != 1) 594 return (ENOTDIR); 595 596 switch (name[0]) { 597 case IPIPCTL_ALLOW: 598 NET_LOCK(); 599 error = sysctl_int(oldp, oldlenp, newp, newlen, &ipip_allow); 600 NET_UNLOCK(); 601 return (error); 602 case IPIPCTL_STATS: 603 return (ipip_sysctl_ipipstat(oldp, oldlenp, newp)); 604 default: 605 return (ENOPROTOOPT); 606 } 607 /* NOTREACHED */ 608 } 609