if_stf.c revision 71959
1/* $FreeBSD: head/sys/net/if_stf.c 71959 2001-02-03 11:46:35Z phk $ */ 2/* $KAME: if_stf.c,v 1.42 2000/08/15 07:24:23 itojun Exp $ */ 3 4/* 5 * Copyright (C) 2000 WIDE Project. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the project nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33/* 34 * 6to4 interface, based on draft-ietf-ngtrans-6to4-06.txt. 35 * 36 * 6to4 interface is NOT capable of link-layer (I mean, IPv4) multicasting. 37 * There is no address mapping defined from IPv6 multicast address to IPv4 38 * address. Therefore, we do not have IFF_MULTICAST on the interface. 39 * 40 * Due to the lack of address mapping for link-local addresses, we cannot 41 * throw packets toward link-local addresses (fe80::x). Also, we cannot throw 42 * packets to link-local multicast addresses (ff02::x). 43 * 44 * Here are interesting symptoms due to the lack of link-local address: 45 * 46 * Unicast routing exchange: 47 * - RIPng: Impossible. Uses link-local multicast packet toward ff02::9, 48 * and link-local addresses as nexthop. 49 * - OSPFv6: Impossible. OSPFv6 assumes that there's link-local address 50 * assigned to the link, and makes use of them. Also, HELLO packets use 51 * link-local multicast addresses (ff02::5 and ff02::6). 52 * - BGP4+: Maybe. You can only use global address as nexthop, and global 53 * address as TCP endpoint address. 54 * 55 * Multicast routing protocols: 56 * - PIM: Hello packet cannot be used to discover adjacent PIM routers. 57 * Adjacent PIM routers must be configured manually (is it really spec-wise 58 * correct thing to do?). 59 * 60 * ICMPv6: 61 * - Redirects cannot be used due to the lack of link-local address. 62 * 63 * Starting from 04 draft, the specification suggests how to construct 64 * link-local address for 6to4 interface. 65 * However, it seems to have no real use and does not help the above symptom 66 * much. Even if we assign link-locals to interface, we cannot really 67 * use link-local unicast/multicast on top of 6to4 cloud, and the above 68 * analysis does not change. 69 * 70 * 6to4 interface has security issues. Refer to 71 * http://playground.iijlab.net/i-d/draft-itojun-ipv6-transition-abuse-00.txt 72 * for details. The code tries to filter out some of malicious packets. 73 * Note that there is no way to be 100% secure. 74 */ 75 76#include "opt_inet.h" 77#include "opt_inet6.h" 78 79#include <sys/param.h> 80#include <sys/systm.h> 81#include <sys/socket.h> 82#include <sys/sockio.h> 83#include <sys/mbuf.h> 84#include <sys/errno.h> 85#include <sys/protosw.h> 86#include <sys/kernel.h> 87#include <machine/cpu.h> 88 89#include <sys/malloc.h> 90 91#include <net/if.h> 92#include <net/route.h> 93#include <net/netisr.h> 94#include <net/if_types.h> 95#include <net/if_stf.h> 96 97#include <netinet/in.h> 98#include <netinet/in_systm.h> 99#include <netinet/ip.h> 100#include <netinet/ip_var.h> 101#include <netinet/in_var.h> 102 103#include <netinet/ip6.h> 104#include <netinet6/ip6_var.h> 105#include <netinet6/in6_gif.h> 106#include <netinet6/in6_var.h> 107#include <netinet/ip_ecn.h> 108 109#include <netinet/ip_encap.h> 110 111#include <machine/stdarg.h> 112 113#include <net/net_osdep.h> 114 115#include "bpf.h" 116#define NBPFILTER NBPF 117#include "stf.h" 118#include "gif.h" /*XXX*/ 119 120#if NBPFILTER > 0 121#include <net/bpf.h> 122#endif 123 124#if NGIF > 0 125#include <net/if_gif.h> 126#endif 127 128#if NSTF > 0 129#if NSTF != 1 130# error only single stf interface allowed 131#endif 132 133#define IN6_IS_ADDR_6TO4(x) (ntohs((x)->s6_addr16[0]) == 0x2002) 134#define GET_V4(x) ((struct in_addr *)(&(x)->s6_addr16[1])) 135 136struct stf_softc { 137 struct ifnet sc_if; /* common area */ 138 union { 139 struct route __sc_ro4; 140 struct route_in6 __sc_ro6; /* just for safety */ 141 } __sc_ro46; 142#define sc_ro __sc_ro46.__sc_ro4 143 const struct encaptab *encap_cookie; 144}; 145 146static struct stf_softc *stf; 147static int nstf; 148 149#if NGIF > 0 150extern int ip_gif_ttl; /*XXX*/ 151#else 152static int ip_gif_ttl = 40; /*XXX*/ 153#endif 154 155extern struct protosw in_stf_protosw; 156 157void stfattach __P((void *)); 158static int stf_encapcheck __P((const struct mbuf *, int, int, void *)); 159static struct in6_ifaddr *stf_getsrcifa6 __P((struct ifnet *)); 160static int stf_output __P((struct ifnet *, struct mbuf *, struct sockaddr *, 161 struct rtentry *)); 162static int stf_checkaddr4 __P((struct in_addr *, struct ifnet *)); 163static int stf_checkaddr6 __P((struct in6_addr *, struct ifnet *)); 164static void stf_rtrequest __P((int, struct rtentry *, struct sockaddr *)); 165static int stf_ioctl __P((struct ifnet *, u_long, caddr_t)); 166 167void 168stfattach(dummy) 169 void *dummy; 170{ 171 struct stf_softc *sc; 172 int i; 173 const struct encaptab *p; 174 175 nstf = NSTF; 176 stf = malloc(nstf * sizeof(struct stf_softc), M_DEVBUF, M_WAITOK); 177 bzero(stf, nstf * sizeof(struct stf_softc)); 178 sc = stf; 179 180 /* XXX just in case... */ 181 for (i = 0; i < nstf; i++) { 182 sc = &stf[i]; 183 bzero(sc, sizeof(*sc)); 184 sc->sc_if.if_name = "stf"; 185 sc->sc_if.if_unit = i; 186 187 p = encap_attach_func(AF_INET, IPPROTO_IPV6, stf_encapcheck, 188 &in_stf_protosw, sc); 189 if (p == NULL) { 190 printf("%s: attach failed\n", if_name(&sc->sc_if)); 191 continue; 192 } 193 sc->encap_cookie = p; 194 195 sc->sc_if.if_mtu = IPV6_MMTU; 196 sc->sc_if.if_flags = 0; 197 sc->sc_if.if_ioctl = stf_ioctl; 198 sc->sc_if.if_output = stf_output; 199 sc->sc_if.if_type = IFT_STF; 200 sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN; 201 if_attach(&sc->sc_if); 202#if NBPFILTER > 0 203#ifdef HAVE_OLD_BPF 204 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int)); 205#else 206 bpfattach(&sc->sc_if.if_bpf, &sc->sc_if, DLT_NULL, sizeof(u_int)); 207#endif 208#endif 209 } 210} 211 212PSEUDO_SET(stfattach, if_stf); 213 214static int 215stf_encapcheck(m, off, proto, arg) 216 const struct mbuf *m; 217 int off; 218 int proto; 219 void *arg; 220{ 221 struct ip ip; 222 struct in6_ifaddr *ia6; 223 struct stf_softc *sc; 224 struct in_addr a, b; 225 226 sc = (struct stf_softc *)arg; 227 if (sc == NULL) 228 return 0; 229 230 if ((sc->sc_if.if_flags & IFF_UP) == 0) 231 return 0; 232 233 if (proto != IPPROTO_IPV6) 234 return 0; 235 236 /* LINTED const cast */ 237 m_copydata((struct mbuf *)m, 0, sizeof(ip), (caddr_t)&ip); 238 239 if (ip.ip_v != 4) 240 return 0; 241 242 ia6 = stf_getsrcifa6(&sc->sc_if); 243 if (ia6 == NULL) 244 return 0; 245 246 /* 247 * check if IPv4 dst matches the IPv4 address derived from the 248 * local 6to4 address. 249 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:... 250 */ 251 if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst, 252 sizeof(ip.ip_dst)) != 0) 253 return 0; 254 255 /* 256 * check if IPv4 src matches the IPv4 address derived from the 257 * local 6to4 address masked by prefixmask. 258 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24 259 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24 260 */ 261 bzero(&a, sizeof(a)); 262 a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr; 263 a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr; 264 b = ip.ip_src; 265 b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr; 266 if (a.s_addr != b.s_addr) 267 return 0; 268 269 /* stf interface makes single side match only */ 270 return 32; 271} 272 273static struct in6_ifaddr * 274stf_getsrcifa6(ifp) 275 struct ifnet *ifp; 276{ 277 struct ifaddr *ia; 278 struct in_ifaddr *ia4; 279 struct sockaddr_in6 *sin6; 280 struct in_addr in; 281 282 for (ia = TAILQ_FIRST(&ifp->if_addrlist); 283 ia; 284 ia = TAILQ_NEXT(ia, ifa_list)) 285 { 286 if (ia->ifa_addr == NULL) 287 continue; 288 if (ia->ifa_addr->sa_family != AF_INET6) 289 continue; 290 sin6 = (struct sockaddr_in6 *)ia->ifa_addr; 291 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) 292 continue; 293 294 bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in)); 295 for (ia4 = TAILQ_FIRST(&in_ifaddrhead); 296 ia4; 297 ia4 = TAILQ_NEXT(ia4, ia_link)) 298 { 299 if (ia4->ia_addr.sin_addr.s_addr == in.s_addr) 300 break; 301 } 302 if (ia4 == NULL) 303 continue; 304 305 return (struct in6_ifaddr *)ia; 306 } 307 308 return NULL; 309} 310 311static int 312stf_output(ifp, m, dst, rt) 313 struct ifnet *ifp; 314 struct mbuf *m; 315 struct sockaddr *dst; 316 struct rtentry *rt; 317{ 318 struct stf_softc *sc; 319 struct sockaddr_in6 *dst6; 320 struct sockaddr_in *dst4; 321 u_int8_t tos; 322 struct ip *ip; 323 struct ip6_hdr *ip6; 324 struct in6_ifaddr *ia6; 325 326 sc = (struct stf_softc*)ifp; 327 dst6 = (struct sockaddr_in6 *)dst; 328 329 /* just in case */ 330 if ((ifp->if_flags & IFF_UP) == 0) { 331 m_freem(m); 332 return ENETDOWN; 333 } 334 335 /* 336 * If we don't have an ip4 address that match my inner ip6 address, 337 * we shouldn't generate output. Without this check, we'll end up 338 * using wrong IPv4 source. 339 */ 340 ia6 = stf_getsrcifa6(ifp); 341 if (ia6 == NULL) { 342 m_freem(m); 343 return ENETDOWN; 344 } 345 346 if (m->m_len < sizeof(*ip6)) { 347 m = m_pullup(m, sizeof(*ip6)); 348 if (!m) 349 return ENOBUFS; 350 } 351 ip6 = mtod(m, struct ip6_hdr *); 352 tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 353 354 M_PREPEND(m, sizeof(struct ip), M_DONTWAIT); 355 if (m && m->m_len < sizeof(struct ip)) 356 m = m_pullup(m, sizeof(struct ip)); 357 if (m == NULL) 358 return ENOBUFS; 359 ip = mtod(m, struct ip *); 360 361 bzero(ip, sizeof(*ip)); 362 363 bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr), 364 &ip->ip_src, sizeof(ip->ip_src)); 365 bcopy(GET_V4(&dst6->sin6_addr), &ip->ip_dst, sizeof(ip->ip_dst)); 366 ip->ip_p = IPPROTO_IPV6; 367 ip->ip_ttl = ip_gif_ttl; /*XXX*/ 368 ip->ip_len = m->m_pkthdr.len; /*host order*/ 369 if (ifp->if_flags & IFF_LINK1) 370 ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos); 371 372 dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst; 373 if (dst4->sin_family != AF_INET || 374 bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) { 375 /* cache route doesn't match */ 376 dst4->sin_family = AF_INET; 377 dst4->sin_len = sizeof(struct sockaddr_in); 378 bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr)); 379 if (sc->sc_ro.ro_rt) { 380 RTFREE(sc->sc_ro.ro_rt); 381 sc->sc_ro.ro_rt = NULL; 382 } 383 } 384 385 if (sc->sc_ro.ro_rt == NULL) { 386 rtalloc(&sc->sc_ro); 387 if (sc->sc_ro.ro_rt == NULL) { 388 m_freem(m); 389 return ENETUNREACH; 390 } 391 } 392 393 return ip_output(m, NULL, &sc->sc_ro, 0, NULL); 394} 395 396static int 397stf_checkaddr4(in, ifp) 398 struct in_addr *in; 399 struct ifnet *ifp; /* incoming interface */ 400{ 401 struct in_ifaddr *ia4; 402 403 /* 404 * reject packets with the following address: 405 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8 406 */ 407 if (IN_MULTICAST(ntohl(in->s_addr))) 408 return -1; 409 switch ((ntohl(in->s_addr) & 0xff000000) >> 24) { 410 case 0: case 127: case 255: 411 return -1; 412 } 413 414 /* 415 * reject packets with broadcast 416 */ 417 for (ia4 = TAILQ_FIRST(&in_ifaddrhead); 418 ia4; 419 ia4 = TAILQ_NEXT(ia4, ia_link)) 420 { 421 if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0) 422 continue; 423 if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr) 424 return -1; 425 } 426 427 /* 428 * perform ingress filter 429 */ 430 if (ifp) { 431 struct sockaddr_in sin; 432 struct rtentry *rt; 433 434 bzero(&sin, sizeof(sin)); 435 sin.sin_family = AF_INET; 436 sin.sin_len = sizeof(struct sockaddr_in); 437 sin.sin_addr = *in; 438 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); 439 if (!rt) 440 return -1; 441 if (rt->rt_ifp != ifp) { 442 rtfree(rt); 443 return -1; 444 } 445 rtfree(rt); 446 } 447 448 return 0; 449} 450 451static int 452stf_checkaddr6(in6, ifp) 453 struct in6_addr *in6; 454 struct ifnet *ifp; /* incoming interface */ 455{ 456 /* 457 * check 6to4 addresses 458 */ 459 if (IN6_IS_ADDR_6TO4(in6)) 460 return stf_checkaddr4(GET_V4(in6), ifp); 461 462 /* 463 * reject anything that look suspicious. the test is implemented 464 * in ip6_input too, but we check here as well to 465 * (1) reject bad packets earlier, and 466 * (2) to be safe against future ip6_input change. 467 */ 468 if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6)) 469 return -1; 470 471 return 0; 472} 473 474void 475#if __STDC__ 476in_stf_input(struct mbuf *m, ...) 477#else 478in_stf_input(m, va_alist) 479 register struct mbuf *m; 480#endif 481{ 482 int off, proto; 483 struct stf_softc *sc; 484 struct ip *ip; 485 struct ip6_hdr *ip6; 486 u_int8_t otos, itos; 487 int len, isr; 488 struct ifqueue *ifq = NULL; 489 struct ifnet *ifp; 490 va_list ap; 491 492 va_start(ap, m); 493 off = va_arg(ap, int); 494 proto = va_arg(ap, int); 495 va_end(ap); 496 497 if (proto != IPPROTO_IPV6) { 498 m_freem(m); 499 return; 500 } 501 502 ip = mtod(m, struct ip *); 503 504 sc = (struct stf_softc *)encap_getarg(m); 505 506 if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) { 507 m_freem(m); 508 return; 509 } 510 511 ifp = &sc->sc_if; 512 513 /* 514 * perform sanity check against outer src/dst. 515 * for source, perform ingress filter as well. 516 */ 517 if (stf_checkaddr4(&ip->ip_dst, NULL) < 0 || 518 stf_checkaddr4(&ip->ip_src, m->m_pkthdr.rcvif) < 0) { 519 m_freem(m); 520 return; 521 } 522 523 otos = ip->ip_tos; 524 m_adj(m, off); 525 526 if (m->m_len < sizeof(*ip6)) { 527 m = m_pullup(m, sizeof(*ip6)); 528 if (!m) 529 return; 530 } 531 ip6 = mtod(m, struct ip6_hdr *); 532 533 /* 534 * perform sanity check against inner src/dst. 535 * for source, perform ingress filter as well. 536 */ 537 if (stf_checkaddr6(&ip6->ip6_dst, NULL) < 0 || 538 stf_checkaddr6(&ip6->ip6_src, m->m_pkthdr.rcvif) < 0) { 539 m_freem(m); 540 return; 541 } 542 543 itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 544 if ((ifp->if_flags & IFF_LINK1) != 0) 545 ip_ecn_egress(ECN_ALLOWED, &otos, &itos); 546 ip6->ip6_flow &= ~htonl(0xff << 20); 547 ip6->ip6_flow |= htonl((u_int32_t)itos << 20); 548 549 m->m_pkthdr.rcvif = ifp; 550 551#if NBPFILTER > 0 552 if (ifp->if_bpf) { 553 /* 554 * We need to prepend the address family as 555 * a four byte field. Cons up a dummy header 556 * to pacify bpf. This is safe because bpf 557 * will only read from the mbuf (i.e., it won't 558 * try to free it or keep a pointer a to it). 559 */ 560 struct mbuf m0; 561 u_int af = AF_INET6; 562 563 m0.m_next = m; 564 m0.m_len = 4; 565 m0.m_data = (char *)⁡ 566 567#ifdef HAVE_OLD_BPF 568 bpf_mtap(ifp, &m0); 569#else 570 bpf_mtap(ifp->if_bpf, &m0); 571#endif 572 } 573#endif /*NBPFILTER > 0*/ 574 575 /* 576 * Put the packet to the network layer input queue according to the 577 * specified address family. 578 * See net/if_gif.c for possible issues with packet processing 579 * reorder due to extra queueing. 580 */ 581 ifq = &ip6intrq; 582 isr = NETISR_IPV6; 583 584 len = m->m_pkthdr.len; 585 if (! IF_HANDOFF(ifq, m, NULL)) 586 return; 587 schednetisr(isr); 588 ifp->if_ipackets++; 589 ifp->if_ibytes += len; 590} 591 592/* ARGSUSED */ 593static void 594stf_rtrequest(cmd, rt, sa) 595 int cmd; 596 struct rtentry *rt; 597#if defined(__bsdi__) && _BSDI_VERSION >= 199802 598 struct rt_addrinfo *sa; 599#else 600 struct sockaddr *sa; 601#endif 602{ 603 604 if (rt) 605 rt->rt_rmx.rmx_mtu = IPV6_MMTU; 606} 607 608static int 609stf_ioctl(ifp, cmd, data) 610 struct ifnet *ifp; 611 u_long cmd; 612 caddr_t data; 613{ 614 struct ifaddr *ifa; 615 struct ifreq *ifr; 616 struct sockaddr_in6 *sin6; 617 int error; 618 619 error = 0; 620 switch (cmd) { 621 case SIOCSIFADDR: 622 ifa = (struct ifaddr *)data; 623 if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) { 624 error = EAFNOSUPPORT; 625 break; 626 } 627 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr; 628 if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) { 629 ifa->ifa_rtrequest = stf_rtrequest; 630 ifp->if_flags |= IFF_UP; 631 } else 632 error = EINVAL; 633 break; 634 635 case SIOCADDMULTI: 636 case SIOCDELMULTI: 637 ifr = (struct ifreq *)data; 638 if (ifr && ifr->ifr_addr.sa_family == AF_INET6) 639 ; 640 else 641 error = EAFNOSUPPORT; 642 break; 643 644 default: 645 error = EINVAL; 646 break; 647 } 648 649 return error; 650} 651 652#endif /* NSTF > 0 */ 653