ipsec_input.c revision 1.78
1 /* $NetBSD: ipsec_input.c,v 1.78 2022/08/23 09:25:10 knakahara Exp $ */ 2 /* $FreeBSD: ipsec_input.c,v 1.2.4.2 2003/03/28 20:32:53 sam Exp $ */ 3 /* $OpenBSD: ipsec_input.c,v 1.63 2003/02/20 18:35:43 deraadt Exp $ */ 4 5 /* 6 * The authors of this code are John Ioannidis (ji (at) tla.org), 7 * Angelos D. Keromytis (kermit (at) csd.uch.gr) and 8 * Niels Provos (provos (at) physnet.uni-hamburg.de). 9 * 10 * This code was written by John Ioannidis for BSD/OS in Athens, Greece, 11 * in November 1995. 12 * 13 * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996, 14 * by Angelos D. Keromytis. 15 * 16 * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis 17 * and Niels Provos. 18 * 19 * Additional features in 1999 by Angelos D. Keromytis. 20 * 21 * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis, 22 * Angelos D. Keromytis and Niels Provos. 23 * Copyright (c) 2001, Angelos D. Keromytis. 24 * 25 * Permission to use, copy, and modify this software with or without fee 26 * is hereby granted, provided that this entire notice is included in 27 * all copies of any software which is or includes a copy or 28 * modification of this software. 29 * You may use this code under the GNU public license if you so wish. Please 30 * contribute changes back to the authors under this freer than GPL license 31 * so that we may further the use of strong encryption without limitations to 32 * all. 33 * 34 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR 35 * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY 36 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE 37 * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR 38 * PURPOSE. 39 */ 40 41 #include <sys/cdefs.h> 42 __KERNEL_RCSID(0, "$NetBSD: ipsec_input.c,v 1.78 2022/08/23 09:25:10 knakahara Exp $"); 43 44 /* 45 * IPsec input processing. 46 */ 47 48 #if defined(_KERNEL_OPT) 49 #include "opt_inet.h" 50 #endif 51 52 #include <sys/param.h> 53 #include <sys/systm.h> 54 #include <sys/mbuf.h> 55 #include <sys/domain.h> 56 #include <sys/protosw.h> 57 #include <sys/socket.h> 58 #include <sys/errno.h> 59 #include <sys/syslog.h> 60 61 #include <net/if.h> 62 #include <net/route.h> 63 64 #include <netinet/in.h> 65 #include <netinet/in_systm.h> 66 #include <netinet/ip.h> 67 #include <netinet/ip_var.h> 68 #include <netinet/in_var.h> 69 #include <netinet/in_proto.h> 70 #include <netinet/udp.h> 71 #include <netinet/tcp.h> 72 73 #include <netinet/ip6.h> 74 #ifdef INET6 75 #include <netinet6/in6.h> 76 #include <netinet6/ip6_var.h> 77 #include <netinet6/ip6_private.h> 78 #include <netinet6/scope6_var.h> 79 #endif 80 #include <netinet/in_pcb.h> 81 82 #include <netipsec/ipsec.h> 83 #include <netipsec/ipsec_private.h> 84 #ifdef INET6 85 #include <netipsec/ipsec6.h> 86 #endif 87 #include <netipsec/ah_var.h> 88 #include <netipsec/esp.h> 89 #include <netipsec/esp_var.h> 90 #include <netipsec/ipcomp_var.h> 91 92 #include <netipsec/key.h> 93 #include <netipsec/keydb.h> 94 95 #include <netipsec/xform.h> 96 #include <netinet6/ip6protosw.h> 97 98 #define IPSEC_ISTAT(p, x, y, z) \ 99 do { \ 100 switch (p) { \ 101 case IPPROTO_ESP: \ 102 ESP_STATINC(x); \ 103 break; \ 104 case IPPROTO_AH: \ 105 AH_STATINC(y); \ 106 break; \ 107 default: \ 108 IPCOMP_STATINC(z); \ 109 break; \ 110 } \ 111 } while (/*CONSTCOND*/0) 112 113 /* 114 * fixup TCP/UDP checksum 115 * 116 * XXX: if we have NAT-OA payload from IKE server, 117 * we must do the differential update of checksum. 118 * 119 * XXX: NAT-OAi/NAT-OAr derived from IKE initiator/responder. 120 * how to know the IKE side from kernel? 121 */ 122 static struct mbuf * 123 ipsec4_fixup_checksum(struct mbuf *m) 124 { 125 struct ip *ip; 126 struct tcphdr *th; 127 struct udphdr *uh; 128 int poff, off; 129 int plen; 130 131 if (m->m_len < sizeof(*ip)) { 132 m = m_pullup(m, sizeof(*ip)); 133 if (m == NULL) 134 return NULL; 135 } 136 ip = mtod(m, struct ip *); 137 poff = ip->ip_hl << 2; 138 plen = ntohs(ip->ip_len) - poff; 139 140 switch (ip->ip_p) { 141 case IPPROTO_TCP: 142 M_REGION_GET(th, struct tcphdr *, m, poff, sizeof(*th)); 143 if (th == NULL) 144 return NULL; 145 off = th->th_off << 2; 146 if (off < sizeof(*th) || off > plen) { 147 m_freem(m); 148 return NULL; 149 } 150 th->th_sum = 0; 151 th->th_sum = in4_cksum(m, IPPROTO_TCP, poff, plen); 152 break; 153 case IPPROTO_UDP: 154 M_REGION_GET(uh, struct udphdr *, m, poff, sizeof(*uh)); 155 if (uh == NULL) 156 return NULL; 157 off = sizeof(*uh); 158 if (off > plen) { 159 m_freem(m); 160 return NULL; 161 } 162 uh->uh_sum = 0; 163 uh->uh_sum = in4_cksum(m, IPPROTO_UDP, poff, plen); 164 break; 165 default: 166 /* no checksum */ 167 return m; 168 } 169 170 return m; 171 } 172 173 static void 174 nat_t_ports_get(struct mbuf *m, uint16_t *dport, uint16_t *sport) 175 { 176 struct m_tag *tag; 177 178 if ((tag = m_tag_find(m, PACKET_TAG_IPSEC_NAT_T_PORTS))) { 179 *sport = ((uint16_t *)(tag + 1))[0]; 180 *dport = ((uint16_t *)(tag + 1))[1]; 181 } else 182 *sport = *dport = 0; 183 } 184 185 static uint32_t 186 spi_get(struct mbuf *m, int sproto, int skip) 187 { 188 uint32_t spi; 189 uint16_t cpi; 190 191 switch (sproto) { 192 case IPPROTO_ESP: 193 m_copydata(m, skip, sizeof(spi), &spi); 194 return spi; 195 case IPPROTO_AH: 196 m_copydata(m, skip + sizeof(spi), sizeof(spi), &spi); 197 return spi; 198 case IPPROTO_IPCOMP: 199 m_copydata(m, skip + sizeof(cpi), sizeof(cpi), &cpi); 200 return htonl(ntohs(cpi)); 201 default: 202 panic("%s called with bad protocol number: %d\n", __func__, 203 sproto); 204 } 205 } 206 207 208 /* 209 * ipsec_common_input gets called when an IPsec-protected packet 210 * is received by IPv4 or IPv6. Its job is to find the right SA 211 * and call the appropriate transform. The transform callback 212 * takes care of further processing (like ingress filtering). 213 */ 214 static int 215 ipsec_common_input(struct mbuf *m, int skip, int protoff, int af, int sproto) 216 { 217 char buf[IPSEC_ADDRSTRLEN], buf2[IPSEC_ADDRSTRLEN]; 218 union sockaddr_union src_address, dst_address; 219 struct secasvar *sav; 220 u_int32_t spi; 221 u_int16_t sport; 222 u_int16_t dport; 223 int s, error; 224 225 IPSEC_ISTAT(sproto, ESP_STAT_INPUT, AH_STAT_INPUT, 226 IPCOMP_STAT_INPUT); 227 228 KASSERT(m != NULL); 229 230 if ((sproto == IPPROTO_ESP && !esp_enable) || 231 (sproto == IPPROTO_AH && !ah_enable) || 232 (sproto == IPPROTO_IPCOMP && !ipcomp_enable)) { 233 m_freem(m); 234 IPSEC_ISTAT(sproto, ESP_STAT_PDROPS, AH_STAT_PDROPS, 235 IPCOMP_STAT_PDROPS); 236 return EOPNOTSUPP; 237 } 238 239 if (m->m_pkthdr.len - skip < 2 * sizeof(u_int32_t)) { 240 m_freem(m); 241 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 242 IPCOMP_STAT_HDROPS); 243 IPSECLOG(LOG_DEBUG, "packet too small\n"); 244 return EINVAL; 245 } 246 247 /* Retrieve the SPI from the relevant IPsec header */ 248 spi = spi_get(m, sproto, skip); 249 250 /* find the source port for NAT-T */ 251 nat_t_ports_get(m, &dport, &sport); 252 253 /* 254 * Find the SA and (indirectly) call the appropriate 255 * kernel crypto routine. The resulting mbuf chain is a valid 256 * IP packet ready to go through input processing. 257 */ 258 memset(&src_address, 0, sizeof (src_address)); 259 memset(&dst_address, 0, sizeof(dst_address)); 260 src_address.sa.sa_family = af; 261 dst_address.sa.sa_family = af; 262 switch (af) { 263 #ifdef INET 264 case AF_INET: 265 src_address.sin.sin_len = sizeof(struct sockaddr_in); 266 dst_address.sin.sin_len = sizeof(struct sockaddr_in); 267 m_copydata(m, offsetof(struct ip, ip_src), 268 sizeof(struct in_addr), 269 &src_address.sin.sin_addr); 270 m_copydata(m, offsetof(struct ip, ip_dst), 271 sizeof(struct in_addr), 272 &dst_address.sin.sin_addr); 273 break; 274 #endif 275 #ifdef INET6 276 case AF_INET6: 277 src_address.sin6.sin6_len = sizeof(struct sockaddr_in6); 278 dst_address.sin6.sin6_len = sizeof(struct sockaddr_in6); 279 m_copydata(m, offsetof(struct ip6_hdr, ip6_src), 280 sizeof(struct in6_addr), 281 &src_address.sin6.sin6_addr); 282 m_copydata(m, offsetof(struct ip6_hdr, ip6_dst), 283 sizeof(struct in6_addr), 284 &dst_address.sin6.sin6_addr); 285 if (sa6_recoverscope(&dst_address.sin6)) { 286 m_freem(m); 287 return EINVAL; 288 } 289 break; 290 #endif 291 default: 292 IPSECLOG(LOG_DEBUG, "unsupported protocol family %u\n", af); 293 m_freem(m); 294 IPSEC_ISTAT(sproto, ESP_STAT_NOPF, AH_STAT_NOPF, 295 IPCOMP_STAT_NOPF); 296 return EPFNOSUPPORT; 297 } 298 299 s = splsoftnet(); 300 301 /* NB: only pass dst since key_lookup_sa follows RFC2401 */ 302 sav = KEY_LOOKUP_SA(&dst_address, sproto, spi, sport, dport); 303 if (sav == NULL) { 304 static struct timeval lasttime = {0, 0}; 305 static int curpps = 0; 306 307 if (!ipsec_debug && ppsratecheck(&lasttime, &curpps, 1)) { 308 if (sport || dport) { 309 log(LOG_INFO, 310 "no key association found for SA" 311 " %s[%u]-%s[%u]/SPI 0x%08lx\n", 312 ipsec_address(&src_address, buf, sizeof(buf)), 313 ntohs(sport), 314 ipsec_address(&dst_address, buf2, sizeof(buf2)), 315 ntohs(dport), 316 (u_long) ntohl(spi)); 317 } else { 318 log(LOG_INFO, 319 "no key association found for" 320 " SA %s-%s/SPI 0x%08lx\n", 321 ipsec_address(&src_address, buf, sizeof(buf)), 322 ipsec_address(&src_address, buf2, sizeof(buf2)), 323 (u_long) ntohl(spi)); 324 } 325 } else if (ipsec_debug) { 326 IPSECLOG(LOG_DEBUG, 327 "no key association found for SA " 328 "%s-%s/SPI 0x%08lx/PROTO %u/PORT %u-%u\n", 329 ipsec_address(&src_address, buf, sizeof(buf)), 330 ipsec_address(&dst_address, buf2, sizeof(buf2)), 331 (u_long) ntohl(spi), sproto, ntohs(dport), ntohs(sport)); 332 } 333 IPSEC_ISTAT(sproto, ESP_STAT_NOTDB, AH_STAT_NOTDB, 334 IPCOMP_STAT_NOTDB); 335 splx(s); 336 m_freem(m); 337 return ENOENT; 338 } 339 340 KASSERT(sav->tdb_xform != NULL); 341 342 /* 343 * Call appropriate transform and return -- callback takes care of 344 * everything else. 345 */ 346 error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff); 347 KEY_SA_UNREF(&sav); 348 splx(s); 349 return error; 350 } 351 352 #ifdef INET 353 /* 354 * Common input handler for IPv4 AH, ESP, and IPCOMP. 355 */ 356 void 357 ipsec4_common_input(struct mbuf *m, int off, int proto) 358 { 359 (void)ipsec_common_input(m, off, offsetof(struct ip, ip_p), 360 AF_INET, proto); 361 } 362 363 /* 364 * IPsec input callback for INET protocols. 365 * This routine is called as the transform callback. 366 * Takes care of filtering and other sanity checks on 367 * the processed packet. 368 */ 369 int 370 ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav, 371 int skip, int protoff) 372 { 373 int prot, af __diagused, sproto; 374 struct ip *ip; 375 struct secasindex *saidx; 376 int error; 377 378 if (__predict_false(m == NULL)) { 379 panic("%s: NULL mbuf", __func__); 380 } 381 if (__predict_false(skip < sizeof(struct ip))) { 382 panic("%s: short skip", __func__); 383 } 384 385 KASSERT(sav != NULL); 386 saidx = &sav->sah->saidx; 387 af = saidx->dst.sa.sa_family; 388 KASSERTMSG(af == AF_INET, "unexpected af %u", af); 389 sproto = saidx->proto; 390 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || 391 sproto == IPPROTO_IPCOMP, 392 "unexpected security protocol %u", sproto); 393 394 /* 395 * Update the IPv4 header. The length of the packet may have changed, 396 * so fix it, and recompute the checksum. 397 */ 398 if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) { 399 char buf[IPSEC_ADDRSTRLEN]; 400 cantpull: 401 IPSECLOG(LOG_DEBUG, 402 "processing failed for SA %s/%08lx\n", 403 ipsec_address(&sav->sah->saidx.dst, buf, 404 sizeof(buf)), (u_long) ntohl(sav->spi)); 405 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 406 IPCOMP_STAT_HDROPS); 407 error = ENOBUFS; 408 goto bad; 409 } 410 ip = mtod(m, struct ip *); 411 ip->ip_len = htons(m->m_pkthdr.len); 412 ip->ip_sum = 0; 413 ip->ip_sum = in_cksum(m, ip->ip_hl << 2); 414 415 /* 416 * Update TCP/UDP checksum 417 * XXX: should only do it in NAT-T case 418 * XXX: should do it incrementally, see FreeBSD code. 419 */ 420 m = ipsec4_fixup_checksum(m); 421 if (m == NULL) 422 goto cantpull; 423 ip = mtod(m, struct ip *); 424 425 prot = ip->ip_p; 426 427 M_VERIFY_PACKET(m); 428 429 key_sa_recordxfer(sav, m); 430 431 if ((inetsw[ip_protox[prot]].pr_flags & PR_LASTHDR) != 0 && 432 ipsec_in_reject(m, NULL)) { 433 error = EINVAL; 434 goto bad; 435 } 436 437 /* 438 * There is no struct ifnet for tunnel mode IP-IP tunnel connecttion, 439 * so we cannot write filtering rule to the inner packet. 440 */ 441 if (saidx->mode == IPSEC_MODE_TUNNEL) 442 m->m_pkthdr.pkthdr_flags |= PKTHDR_FLAG_IPSEC_SKIP_PFIL; 443 444 (*inetsw[ip_protox[prot]].pr_input)(m, skip, prot); 445 return 0; 446 447 bad: 448 m_freem(m); 449 return error; 450 } 451 #endif /* INET */ 452 453 #ifdef INET6 454 int 455 ipsec6_common_input(struct mbuf **mp, int *offp, int proto) 456 { 457 int l = 0; 458 int protoff, nxt; 459 struct ip6_ext ip6e; 460 461 if (*offp < sizeof(struct ip6_hdr)) { 462 IPSECLOG(LOG_DEBUG, "bad offset %u\n", *offp); 463 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 464 IPCOMP_STAT_HDROPS); 465 m_freem(*mp); 466 return IPPROTO_DONE; 467 } else if (*offp == sizeof(struct ip6_hdr)) { 468 protoff = offsetof(struct ip6_hdr, ip6_nxt); 469 } else { 470 /* Chase down the header chain... */ 471 protoff = sizeof(struct ip6_hdr); 472 nxt = (mtod(*mp, struct ip6_hdr *))->ip6_nxt; 473 474 do { 475 protoff += l; 476 m_copydata(*mp, protoff, sizeof(ip6e), &ip6e); 477 478 if (nxt == IPPROTO_AH) 479 l = (ip6e.ip6e_len + 2) << 2; 480 else if (nxt == IPPROTO_FRAGMENT) 481 l = sizeof(struct ip6_frag); 482 else 483 l = (ip6e.ip6e_len + 1) << 3; 484 KASSERT(l > 0); 485 486 nxt = ip6e.ip6e_nxt; 487 } while (protoff + l < *offp); 488 489 /* Malformed packet check */ 490 if (protoff + l != *offp) { 491 IPSECLOG(LOG_DEBUG, "bad packet header chain, " 492 "protoff %u, l %u, off %u\n", protoff, l, *offp); 493 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, 494 AH_STAT_HDROPS, 495 IPCOMP_STAT_HDROPS); 496 m_freem(*mp); 497 *mp = NULL; 498 return IPPROTO_DONE; 499 } 500 protoff += offsetof(struct ip6_ext, ip6e_nxt); 501 } 502 (void) ipsec_common_input(*mp, *offp, protoff, AF_INET6, proto); 503 return IPPROTO_DONE; 504 } 505 506 /* 507 * IPsec input callback, called by the transform callback. Takes care of 508 * filtering and other sanity checks on the processed packet. 509 */ 510 int 511 ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip, 512 int protoff) 513 { 514 int af __diagused, sproto; 515 struct ip6_hdr *ip6; 516 struct secasindex *saidx; 517 int nxt; 518 u_int8_t prot; 519 int error, nest; 520 521 if (__predict_false(m == NULL)) { 522 panic("%s: NULL mbuf", __func__); 523 } 524 525 KASSERT(sav != NULL); 526 saidx = &sav->sah->saidx; 527 af = saidx->dst.sa.sa_family; 528 KASSERTMSG(af == AF_INET6, "unexpected af %u", af); 529 sproto = saidx->proto; 530 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || 531 sproto == IPPROTO_IPCOMP, 532 "unexpected security protocol %u", sproto); 533 534 /* Fix IPv6 header */ 535 if (m->m_len < sizeof(struct ip6_hdr) && 536 (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 537 char buf[IPSEC_ADDRSTRLEN]; 538 IPSECLOG(LOG_DEBUG, "processing failed for SA %s/%08lx\n", 539 ipsec_address(&sav->sah->saidx.dst, 540 buf, sizeof(buf)), (u_long) ntohl(sav->spi)); 541 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 542 IPCOMP_STAT_HDROPS); 543 error = EACCES; 544 goto bad; 545 } 546 547 ip6 = mtod(m, struct ip6_hdr *); 548 ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr)); 549 550 m_copydata(m, protoff, sizeof(prot), &prot); 551 552 key_sa_recordxfer(sav, m); 553 554 /* 555 * See the end of ip6_input for this logic. 556 * IPPROTO_IPV[46] case will be processed just like other ones 557 */ 558 nest = 0; 559 nxt = prot; 560 while (nxt != IPPROTO_DONE) { 561 if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) { 562 IP6_STATINC(IP6_STAT_TOOMANYHDR); 563 error = EINVAL; 564 goto bad; 565 } 566 567 M_VERIFY_PACKET(m); 568 569 /* 570 * Protection against faulty packet - there should be 571 * more sanity checks in header chain processing. 572 */ 573 if (m->m_pkthdr.len < skip) { 574 IP6_STATINC(IP6_STAT_TOOSHORT); 575 in6_ifstat_inc(m_get_rcvif_NOMPSAFE(m), 576 ifs6_in_truncated); 577 error = EINVAL; 578 goto bad; 579 } 580 581 /* 582 * Enforce IPsec policy checking if we are seeing last header. 583 * Note that we do not visit this with protocols with pcb layer 584 * code - like udp/tcp/raw ip. 585 */ 586 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 && 587 ipsec_in_reject(m, NULL)) { 588 error = EINVAL; 589 goto bad; 590 } 591 592 /* 593 * There is no struct ifnet for tunnel mode IP-IP tunnel connecttion, 594 * so we cannot write filtering rule to the inner packet. 595 */ 596 if (saidx->mode == IPSEC_MODE_TUNNEL) 597 m->m_pkthdr.pkthdr_flags |= PKTHDR_FLAG_IPSEC_SKIP_PFIL; 598 599 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt); 600 } 601 return 0; 602 603 bad: 604 if (m) 605 m_freem(m); 606 return error; 607 } 608 #endif /* INET6 */ 609
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