ipsec_input.c revision 1.72
1 /* $NetBSD: ipsec_input.c,v 1.72 2018/10/27 05:42:23 maxv 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 1.72 2018/10/27 05:42:23 maxv 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, NULL))) { 179 *sport = ((uint16_t *)(tag + 1))[0]; 180 *dport = ((uint16_t *)(tag + 1))[1]; 181 } else 182 *sport = *dport = 0; 183 } 184 185 /* 186 * ipsec_common_input gets called when an IPsec-protected packet 187 * is received by IPv4 or IPv6. Its job is to find the right SA 188 * and call the appropriate transform. The transform callback 189 * takes care of further processing (like ingress filtering). 190 */ 191 static int 192 ipsec_common_input(struct mbuf *m, int skip, int protoff, int af, int sproto) 193 { 194 char buf[IPSEC_ADDRSTRLEN]; 195 union sockaddr_union dst_address; 196 struct secasvar *sav; 197 u_int32_t spi; 198 u_int16_t sport; 199 u_int16_t dport; 200 int s, error; 201 202 IPSEC_ISTAT(sproto, ESP_STAT_INPUT, AH_STAT_INPUT, 203 IPCOMP_STAT_INPUT); 204 205 KASSERT(m != NULL); 206 207 if ((sproto == IPPROTO_ESP && !esp_enable) || 208 (sproto == IPPROTO_AH && !ah_enable) || 209 (sproto == IPPROTO_IPCOMP && !ipcomp_enable)) { 210 m_freem(m); 211 IPSEC_ISTAT(sproto, ESP_STAT_PDROPS, AH_STAT_PDROPS, 212 IPCOMP_STAT_PDROPS); 213 return EOPNOTSUPP; 214 } 215 216 if (m->m_pkthdr.len - skip < 2 * sizeof(u_int32_t)) { 217 m_freem(m); 218 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 219 IPCOMP_STAT_HDROPS); 220 IPSECLOG(LOG_DEBUG, "packet too small\n"); 221 return EINVAL; 222 } 223 224 /* Retrieve the SPI from the relevant IPsec header */ 225 if (sproto == IPPROTO_ESP) { 226 m_copydata(m, skip, sizeof(u_int32_t), &spi); 227 } else if (sproto == IPPROTO_AH) { 228 m_copydata(m, skip + sizeof(u_int32_t), sizeof(u_int32_t), &spi); 229 } else if (sproto == IPPROTO_IPCOMP) { 230 u_int16_t cpi; 231 m_copydata(m, skip + sizeof(u_int16_t), sizeof(u_int16_t), &cpi); 232 spi = ntohl(htons(cpi)); 233 } else { 234 panic("%s called with bad protocol number: %d\n", __func__, 235 sproto); 236 } 237 238 /* find the source port for NAT-T */ 239 nat_t_ports_get(m, &dport, &sport); 240 241 /* 242 * Find the SA and (indirectly) call the appropriate 243 * kernel crypto routine. The resulting mbuf chain is a valid 244 * IP packet ready to go through input processing. 245 */ 246 memset(&dst_address, 0, sizeof(dst_address)); 247 dst_address.sa.sa_family = af; 248 switch (af) { 249 #ifdef INET 250 case AF_INET: 251 dst_address.sin.sin_len = sizeof(struct sockaddr_in); 252 m_copydata(m, offsetof(struct ip, ip_dst), 253 sizeof(struct in_addr), 254 &dst_address.sin.sin_addr); 255 break; 256 #endif 257 #ifdef INET6 258 case AF_INET6: 259 dst_address.sin6.sin6_len = sizeof(struct sockaddr_in6); 260 m_copydata(m, offsetof(struct ip6_hdr, ip6_dst), 261 sizeof(struct in6_addr), 262 &dst_address.sin6.sin6_addr); 263 if (sa6_recoverscope(&dst_address.sin6)) { 264 m_freem(m); 265 return EINVAL; 266 } 267 break; 268 #endif 269 default: 270 IPSECLOG(LOG_DEBUG, "unsupported protocol family %u\n", af); 271 m_freem(m); 272 IPSEC_ISTAT(sproto, ESP_STAT_NOPF, AH_STAT_NOPF, 273 IPCOMP_STAT_NOPF); 274 return EPFNOSUPPORT; 275 } 276 277 s = splsoftnet(); 278 279 /* NB: only pass dst since key_lookup_sa follows RFC2401 */ 280 sav = KEY_LOOKUP_SA(&dst_address, sproto, spi, sport, dport); 281 if (sav == NULL) { 282 IPSECLOG(LOG_DEBUG, 283 "no key association found for SA %s/%08lx/%u/%u\n", 284 ipsec_address(&dst_address, buf, sizeof(buf)), 285 (u_long) ntohl(spi), sproto, ntohs(dport)); 286 IPSEC_ISTAT(sproto, ESP_STAT_NOTDB, AH_STAT_NOTDB, 287 IPCOMP_STAT_NOTDB); 288 splx(s); 289 m_freem(m); 290 return ENOENT; 291 } 292 293 KASSERT(sav->tdb_xform != NULL); 294 295 /* 296 * Call appropriate transform and return -- callback takes care of 297 * everything else. 298 */ 299 error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff); 300 KEY_SA_UNREF(&sav); 301 splx(s); 302 return error; 303 } 304 305 #ifdef INET 306 /* 307 * Common input handler for IPv4 AH, ESP, and IPCOMP. 308 */ 309 void 310 ipsec4_common_input(struct mbuf *m, int off, int proto) 311 { 312 (void)ipsec_common_input(m, off, offsetof(struct ip, ip_p), 313 AF_INET, proto); 314 } 315 316 /* 317 * IPsec input callback for INET protocols. 318 * This routine is called as the transform callback. 319 * Takes care of filtering and other sanity checks on 320 * the processed packet. 321 */ 322 int 323 ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav, 324 int skip, int protoff) 325 { 326 int prot, af __diagused, sproto; 327 struct ip *ip; 328 struct secasindex *saidx; 329 int error; 330 331 if (__predict_false(m == NULL)) { 332 panic("%s: NULL mbuf", __func__); 333 } 334 if (__predict_false(skip < sizeof(struct ip))) { 335 panic("%s: short skip", __func__); 336 } 337 338 KASSERT(sav != NULL); 339 saidx = &sav->sah->saidx; 340 af = saidx->dst.sa.sa_family; 341 KASSERTMSG(af == AF_INET, "unexpected af %u", af); 342 sproto = saidx->proto; 343 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || 344 sproto == IPPROTO_IPCOMP, 345 "unexpected security protocol %u", sproto); 346 347 /* 348 * Update the IPv4 header. The length of the packet may have changed, 349 * so fix it, and recompute the checksum. 350 */ 351 if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) { 352 char buf[IPSEC_ADDRSTRLEN]; 353 cantpull: 354 IPSECLOG(LOG_DEBUG, 355 "processing failed for SA %s/%08lx\n", 356 ipsec_address(&sav->sah->saidx.dst, buf, 357 sizeof(buf)), (u_long) ntohl(sav->spi)); 358 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 359 IPCOMP_STAT_HDROPS); 360 error = ENOBUFS; 361 goto bad; 362 } 363 ip = mtod(m, struct ip *); 364 ip->ip_len = htons(m->m_pkthdr.len); 365 ip->ip_sum = 0; 366 ip->ip_sum = in_cksum(m, ip->ip_hl << 2); 367 368 /* 369 * Update TCP/UDP checksum 370 * XXX: should only do it in NAT-T case 371 * XXX: should do it incrementally, see FreeBSD code. 372 */ 373 m = ipsec4_fixup_checksum(m); 374 if (m == NULL) 375 goto cantpull; 376 ip = mtod(m, struct ip *); 377 378 prot = ip->ip_p; 379 380 M_VERIFY_PACKET(m); 381 382 key_sa_recordxfer(sav, m); 383 384 if ((inetsw[ip_protox[prot]].pr_flags & PR_LASTHDR) != 0 && 385 ipsec_in_reject(m, NULL)) { 386 error = EINVAL; 387 goto bad; 388 } 389 (*inetsw[ip_protox[prot]].pr_input)(m, skip, prot); 390 return 0; 391 392 bad: 393 m_freem(m); 394 return error; 395 } 396 #endif /* INET */ 397 398 #ifdef INET6 399 int 400 ipsec6_common_input(struct mbuf **mp, int *offp, int proto) 401 { 402 int l = 0; 403 int protoff, nxt; 404 struct ip6_ext ip6e; 405 406 if (*offp < sizeof(struct ip6_hdr)) { 407 IPSECLOG(LOG_DEBUG, "bad offset %u\n", *offp); 408 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 409 IPCOMP_STAT_HDROPS); 410 m_freem(*mp); 411 return IPPROTO_DONE; 412 } else if (*offp == sizeof(struct ip6_hdr)) { 413 protoff = offsetof(struct ip6_hdr, ip6_nxt); 414 } else { 415 /* Chase down the header chain... */ 416 protoff = sizeof(struct ip6_hdr); 417 nxt = (mtod(*mp, struct ip6_hdr *))->ip6_nxt; 418 419 do { 420 protoff += l; 421 m_copydata(*mp, protoff, sizeof(ip6e), &ip6e); 422 423 if (nxt == IPPROTO_AH) 424 l = (ip6e.ip6e_len + 2) << 2; 425 else if (nxt == IPPROTO_FRAGMENT) 426 l = sizeof(struct ip6_frag); 427 else 428 l = (ip6e.ip6e_len + 1) << 3; 429 KASSERT(l > 0); 430 431 nxt = ip6e.ip6e_nxt; 432 } while (protoff + l < *offp); 433 434 /* Malformed packet check */ 435 if (protoff + l != *offp) { 436 IPSECLOG(LOG_DEBUG, "bad packet header chain, " 437 "protoff %u, l %u, off %u\n", protoff, l, *offp); 438 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, 439 AH_STAT_HDROPS, 440 IPCOMP_STAT_HDROPS); 441 m_freem(*mp); 442 *mp = NULL; 443 return IPPROTO_DONE; 444 } 445 protoff += offsetof(struct ip6_ext, ip6e_nxt); 446 } 447 (void) ipsec_common_input(*mp, *offp, protoff, AF_INET6, proto); 448 return IPPROTO_DONE; 449 } 450 451 /* 452 * IPsec input callback, called by the transform callback. Takes care of 453 * filtering and other sanity checks on the processed packet. 454 */ 455 int 456 ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip, 457 int protoff) 458 { 459 int af __diagused, sproto; 460 struct ip6_hdr *ip6; 461 struct secasindex *saidx; 462 int nxt; 463 u_int8_t prot; 464 int error, nest; 465 466 if (__predict_false(m == NULL)) { 467 panic("%s: NULL mbuf", __func__); 468 } 469 470 KASSERT(sav != NULL); 471 saidx = &sav->sah->saidx; 472 af = saidx->dst.sa.sa_family; 473 KASSERTMSG(af == AF_INET6, "unexpected af %u", af); 474 sproto = saidx->proto; 475 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || 476 sproto == IPPROTO_IPCOMP, 477 "unexpected security protocol %u", sproto); 478 479 /* Fix IPv6 header */ 480 if (m->m_len < sizeof(struct ip6_hdr) && 481 (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 482 char buf[IPSEC_ADDRSTRLEN]; 483 IPSECLOG(LOG_DEBUG, "processing failed for SA %s/%08lx\n", 484 ipsec_address(&sav->sah->saidx.dst, 485 buf, sizeof(buf)), (u_long) ntohl(sav->spi)); 486 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 487 IPCOMP_STAT_HDROPS); 488 error = EACCES; 489 goto bad; 490 } 491 492 ip6 = mtod(m, struct ip6_hdr *); 493 ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr)); 494 495 m_copydata(m, protoff, sizeof(prot), &prot); 496 497 key_sa_recordxfer(sav, m); 498 499 /* 500 * See the end of ip6_input for this logic. 501 * IPPROTO_IPV[46] case will be processed just like other ones 502 */ 503 nest = 0; 504 nxt = prot; 505 while (nxt != IPPROTO_DONE) { 506 if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) { 507 IP6_STATINC(IP6_STAT_TOOMANYHDR); 508 error = EINVAL; 509 goto bad; 510 } 511 512 M_VERIFY_PACKET(m); 513 514 /* 515 * Protection against faulty packet - there should be 516 * more sanity checks in header chain processing. 517 */ 518 if (m->m_pkthdr.len < skip) { 519 IP6_STATINC(IP6_STAT_TOOSHORT); 520 in6_ifstat_inc(m_get_rcvif_NOMPSAFE(m), 521 ifs6_in_truncated); 522 error = EINVAL; 523 goto bad; 524 } 525 526 /* 527 * Enforce IPsec policy checking if we are seeing last header. 528 * Note that we do not visit this with protocols with pcb layer 529 * code - like udp/tcp/raw ip. 530 */ 531 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 && 532 ipsec_in_reject(m, NULL)) { 533 error = EINVAL; 534 goto bad; 535 } 536 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt); 537 } 538 return 0; 539 540 bad: 541 if (m) 542 m_freem(m); 543 return error; 544 } 545 #endif /* INET6 */ 546
Indexes created Thu Sep 25 15:09:46 GMT 2025