ipsec_input.c revision 1.76
1 /* $NetBSD: ipsec_input.c,v 1.76 2022/05/19 19:18:03 christos 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 1.76 2022/05/19 19:18:03 christos 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 drived 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]; 218 union sockaddr_union 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(&dst_address, 0, sizeof(dst_address)); 259 dst_address.sa.sa_family = af; 260 switch (af) { 261 #ifdef INET 262 case AF_INET: 263 dst_address.sin.sin_len = sizeof(struct sockaddr_in); 264 m_copydata(m, offsetof(struct ip, ip_dst), 265 sizeof(struct in_addr), 266 &dst_address.sin.sin_addr); 267 break; 268 #endif 269 #ifdef INET6 270 case AF_INET6: 271 dst_address.sin6.sin6_len = sizeof(struct sockaddr_in6); 272 m_copydata(m, offsetof(struct ip6_hdr, ip6_dst), 273 sizeof(struct in6_addr), 274 &dst_address.sin6.sin6_addr); 275 if (sa6_recoverscope(&dst_address.sin6)) { 276 m_freem(m); 277 return EINVAL; 278 } 279 break; 280 #endif 281 default: 282 IPSECLOG(LOG_DEBUG, "unsupported protocol family %u\n", af); 283 m_freem(m); 284 IPSEC_ISTAT(sproto, ESP_STAT_NOPF, AH_STAT_NOPF, 285 IPCOMP_STAT_NOPF); 286 return EPFNOSUPPORT; 287 } 288 289 s = splsoftnet(); 290 291 /* NB: only pass dst since key_lookup_sa follows RFC2401 */ 292 sav = KEY_LOOKUP_SA(&dst_address, sproto, spi, sport, dport); 293 if (sav == NULL) { 294 IPSECLOG(LOG_DEBUG, 295 "no key association found for SA %s/%08lx/%u/%u\n", 296 ipsec_address(&dst_address, buf, sizeof(buf)), 297 (u_long) ntohl(spi), sproto, ntohs(dport)); 298 IPSEC_ISTAT(sproto, ESP_STAT_NOTDB, AH_STAT_NOTDB, 299 IPCOMP_STAT_NOTDB); 300 splx(s); 301 m_freem(m); 302 return ENOENT; 303 } 304 305 KASSERT(sav->tdb_xform != NULL); 306 307 /* 308 * Call appropriate transform and return -- callback takes care of 309 * everything else. 310 */ 311 error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff); 312 KEY_SA_UNREF(&sav); 313 splx(s); 314 return error; 315 } 316 317 #ifdef INET 318 /* 319 * Common input handler for IPv4 AH, ESP, and IPCOMP. 320 */ 321 void 322 ipsec4_common_input(struct mbuf *m, int off, int proto) 323 { 324 (void)ipsec_common_input(m, off, offsetof(struct ip, ip_p), 325 AF_INET, proto); 326 } 327 328 /* 329 * IPsec input callback for INET protocols. 330 * This routine is called as the transform callback. 331 * Takes care of filtering and other sanity checks on 332 * the processed packet. 333 */ 334 int 335 ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav, 336 int skip, int protoff) 337 { 338 int prot, af __diagused, sproto; 339 struct ip *ip; 340 struct secasindex *saidx; 341 int error; 342 343 if (__predict_false(m == NULL)) { 344 panic("%s: NULL mbuf", __func__); 345 } 346 if (__predict_false(skip < sizeof(struct ip))) { 347 panic("%s: short skip", __func__); 348 } 349 350 KASSERT(sav != NULL); 351 saidx = &sav->sah->saidx; 352 af = saidx->dst.sa.sa_family; 353 KASSERTMSG(af == AF_INET, "unexpected af %u", af); 354 sproto = saidx->proto; 355 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || 356 sproto == IPPROTO_IPCOMP, 357 "unexpected security protocol %u", sproto); 358 359 /* 360 * Update the IPv4 header. The length of the packet may have changed, 361 * so fix it, and recompute the checksum. 362 */ 363 if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) { 364 char buf[IPSEC_ADDRSTRLEN]; 365 cantpull: 366 IPSECLOG(LOG_DEBUG, 367 "processing failed for SA %s/%08lx\n", 368 ipsec_address(&sav->sah->saidx.dst, buf, 369 sizeof(buf)), (u_long) ntohl(sav->spi)); 370 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 371 IPCOMP_STAT_HDROPS); 372 error = ENOBUFS; 373 goto bad; 374 } 375 ip = mtod(m, struct ip *); 376 ip->ip_len = htons(m->m_pkthdr.len); 377 ip->ip_sum = 0; 378 ip->ip_sum = in_cksum(m, ip->ip_hl << 2); 379 380 /* 381 * Update TCP/UDP checksum 382 * XXX: should only do it in NAT-T case 383 * XXX: should do it incrementally, see FreeBSD code. 384 */ 385 m = ipsec4_fixup_checksum(m); 386 if (m == NULL) 387 goto cantpull; 388 ip = mtod(m, struct ip *); 389 390 prot = ip->ip_p; 391 392 M_VERIFY_PACKET(m); 393 394 key_sa_recordxfer(sav, m); 395 396 if ((inetsw[ip_protox[prot]].pr_flags & PR_LASTHDR) != 0 && 397 ipsec_in_reject(m, NULL)) { 398 error = EINVAL; 399 goto bad; 400 } 401 402 /* 403 * There is no struct ifnet for tunnel mode IP-IP tunnel connecttion, 404 * so we cannot write filtering rule to the inner packet. 405 */ 406 if (saidx->mode == IPSEC_MODE_TUNNEL) 407 m->m_pkthdr.pkthdr_flags |= PKTHDR_FLAG_IPSEC_SKIP_PFIL; 408 409 (*inetsw[ip_protox[prot]].pr_input)(m, skip, prot); 410 return 0; 411 412 bad: 413 m_freem(m); 414 return error; 415 } 416 #endif /* INET */ 417 418 #ifdef INET6 419 int 420 ipsec6_common_input(struct mbuf **mp, int *offp, int proto) 421 { 422 int l = 0; 423 int protoff, nxt; 424 struct ip6_ext ip6e; 425 426 if (*offp < sizeof(struct ip6_hdr)) { 427 IPSECLOG(LOG_DEBUG, "bad offset %u\n", *offp); 428 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 429 IPCOMP_STAT_HDROPS); 430 m_freem(*mp); 431 return IPPROTO_DONE; 432 } else if (*offp == sizeof(struct ip6_hdr)) { 433 protoff = offsetof(struct ip6_hdr, ip6_nxt); 434 } else { 435 /* Chase down the header chain... */ 436 protoff = sizeof(struct ip6_hdr); 437 nxt = (mtod(*mp, struct ip6_hdr *))->ip6_nxt; 438 439 do { 440 protoff += l; 441 m_copydata(*mp, protoff, sizeof(ip6e), &ip6e); 442 443 if (nxt == IPPROTO_AH) 444 l = (ip6e.ip6e_len + 2) << 2; 445 else if (nxt == IPPROTO_FRAGMENT) 446 l = sizeof(struct ip6_frag); 447 else 448 l = (ip6e.ip6e_len + 1) << 3; 449 KASSERT(l > 0); 450 451 nxt = ip6e.ip6e_nxt; 452 } while (protoff + l < *offp); 453 454 /* Malformed packet check */ 455 if (protoff + l != *offp) { 456 IPSECLOG(LOG_DEBUG, "bad packet header chain, " 457 "protoff %u, l %u, off %u\n", protoff, l, *offp); 458 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, 459 AH_STAT_HDROPS, 460 IPCOMP_STAT_HDROPS); 461 m_freem(*mp); 462 *mp = NULL; 463 return IPPROTO_DONE; 464 } 465 protoff += offsetof(struct ip6_ext, ip6e_nxt); 466 } 467 (void) ipsec_common_input(*mp, *offp, protoff, AF_INET6, proto); 468 return IPPROTO_DONE; 469 } 470 471 /* 472 * IPsec input callback, called by the transform callback. Takes care of 473 * filtering and other sanity checks on the processed packet. 474 */ 475 int 476 ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip, 477 int protoff) 478 { 479 int af __diagused, sproto; 480 struct ip6_hdr *ip6; 481 struct secasindex *saidx; 482 int nxt; 483 u_int8_t prot; 484 int error, nest; 485 486 if (__predict_false(m == NULL)) { 487 panic("%s: NULL mbuf", __func__); 488 } 489 490 KASSERT(sav != NULL); 491 saidx = &sav->sah->saidx; 492 af = saidx->dst.sa.sa_family; 493 KASSERTMSG(af == AF_INET6, "unexpected af %u", af); 494 sproto = saidx->proto; 495 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || 496 sproto == IPPROTO_IPCOMP, 497 "unexpected security protocol %u", sproto); 498 499 /* Fix IPv6 header */ 500 if (m->m_len < sizeof(struct ip6_hdr) && 501 (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 502 char buf[IPSEC_ADDRSTRLEN]; 503 IPSECLOG(LOG_DEBUG, "processing failed for SA %s/%08lx\n", 504 ipsec_address(&sav->sah->saidx.dst, 505 buf, sizeof(buf)), (u_long) ntohl(sav->spi)); 506 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 507 IPCOMP_STAT_HDROPS); 508 error = EACCES; 509 goto bad; 510 } 511 512 ip6 = mtod(m, struct ip6_hdr *); 513 ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr)); 514 515 m_copydata(m, protoff, sizeof(prot), &prot); 516 517 key_sa_recordxfer(sav, m); 518 519 /* 520 * See the end of ip6_input for this logic. 521 * IPPROTO_IPV[46] case will be processed just like other ones 522 */ 523 nest = 0; 524 nxt = prot; 525 while (nxt != IPPROTO_DONE) { 526 if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) { 527 IP6_STATINC(IP6_STAT_TOOMANYHDR); 528 error = EINVAL; 529 goto bad; 530 } 531 532 M_VERIFY_PACKET(m); 533 534 /* 535 * Protection against faulty packet - there should be 536 * more sanity checks in header chain processing. 537 */ 538 if (m->m_pkthdr.len < skip) { 539 IP6_STATINC(IP6_STAT_TOOSHORT); 540 in6_ifstat_inc(m_get_rcvif_NOMPSAFE(m), 541 ifs6_in_truncated); 542 error = EINVAL; 543 goto bad; 544 } 545 546 /* 547 * Enforce IPsec policy checking if we are seeing last header. 548 * Note that we do not visit this with protocols with pcb layer 549 * code - like udp/tcp/raw ip. 550 */ 551 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 && 552 ipsec_in_reject(m, NULL)) { 553 error = EINVAL; 554 goto bad; 555 } 556 557 /* 558 * There is no struct ifnet for tunnel mode IP-IP tunnel connecttion, 559 * so we cannot write filtering rule to the inner packet. 560 */ 561 if (saidx->mode == IPSEC_MODE_TUNNEL) 562 m->m_pkthdr.pkthdr_flags |= PKTHDR_FLAG_IPSEC_SKIP_PFIL; 563 564 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt); 565 } 566 return 0; 567 568 bad: 569 if (m) 570 m_freem(m); 571 return error; 572 } 573 #endif /* INET6 */ 574
Indexes created Thu Sep 25 16:09:42 GMT 2025