ipsec_input.c revision 1.69
1 /* $NetBSD: ipsec_input.c,v 1.69 2018/04/29 14:54:09 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 1.69 2018/04/29 14:54:09 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 IP6_EXTHDR_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 IP6_EXTHDR_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 /* 174 * ipsec_common_input gets called when an IPsec-protected packet 175 * is received by IPv4 or IPv6. Its job is to find the right SA 176 * and call the appropriate transform. The transform callback 177 * takes care of further processing (like ingress filtering). 178 */ 179 static int 180 ipsec_common_input(struct mbuf *m, int skip, int protoff, int af, int sproto) 181 { 182 char buf[IPSEC_ADDRSTRLEN]; 183 union sockaddr_union dst_address; 184 struct secasvar *sav; 185 u_int32_t spi; 186 u_int16_t sport; 187 u_int16_t dport; 188 int s, error; 189 190 IPSEC_ISTAT(sproto, ESP_STAT_INPUT, AH_STAT_INPUT, 191 IPCOMP_STAT_INPUT); 192 193 KASSERT(m != NULL); 194 195 if ((sproto == IPPROTO_ESP && !esp_enable) || 196 (sproto == IPPROTO_AH && !ah_enable) || 197 (sproto == IPPROTO_IPCOMP && !ipcomp_enable)) { 198 m_freem(m); 199 IPSEC_ISTAT(sproto, ESP_STAT_PDROPS, AH_STAT_PDROPS, 200 IPCOMP_STAT_PDROPS); 201 return EOPNOTSUPP; 202 } 203 204 if (m->m_pkthdr.len - skip < 2 * sizeof(u_int32_t)) { 205 m_freem(m); 206 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 207 IPCOMP_STAT_HDROPS); 208 IPSECLOG(LOG_DEBUG, "packet too small\n"); 209 return EINVAL; 210 } 211 212 /* Retrieve the SPI from the relevant IPsec header */ 213 if (sproto == IPPROTO_ESP) { 214 m_copydata(m, skip, sizeof(u_int32_t), &spi); 215 } else if (sproto == IPPROTO_AH) { 216 m_copydata(m, skip + sizeof(u_int32_t), sizeof(u_int32_t), &spi); 217 } else if (sproto == IPPROTO_IPCOMP) { 218 u_int16_t cpi; 219 m_copydata(m, skip + sizeof(u_int16_t), sizeof(u_int16_t), &cpi); 220 spi = ntohl(htons(cpi)); 221 } else { 222 panic("%s called with bad protocol number: %d\n", __func__, 223 sproto); 224 } 225 226 /* find the source port for NAT-T */ 227 nat_t_ports_get(m, &dport, &sport); 228 229 /* 230 * Find the SA and (indirectly) call the appropriate 231 * kernel crypto routine. The resulting mbuf chain is a valid 232 * IP packet ready to go through input processing. 233 */ 234 memset(&dst_address, 0, sizeof(dst_address)); 235 dst_address.sa.sa_family = af; 236 switch (af) { 237 #ifdef INET 238 case AF_INET: 239 dst_address.sin.sin_len = sizeof(struct sockaddr_in); 240 m_copydata(m, offsetof(struct ip, ip_dst), 241 sizeof(struct in_addr), 242 &dst_address.sin.sin_addr); 243 break; 244 #endif 245 #ifdef INET6 246 case AF_INET6: 247 dst_address.sin6.sin6_len = sizeof(struct sockaddr_in6); 248 m_copydata(m, offsetof(struct ip6_hdr, ip6_dst), 249 sizeof(struct in6_addr), 250 &dst_address.sin6.sin6_addr); 251 if (sa6_recoverscope(&dst_address.sin6)) { 252 m_freem(m); 253 return EINVAL; 254 } 255 break; 256 #endif 257 default: 258 IPSECLOG(LOG_DEBUG, "unsupported protocol family %u\n", af); 259 m_freem(m); 260 IPSEC_ISTAT(sproto, ESP_STAT_NOPF, AH_STAT_NOPF, 261 IPCOMP_STAT_NOPF); 262 return EPFNOSUPPORT; 263 } 264 265 s = splsoftnet(); 266 267 /* NB: only pass dst since key_lookup_sa follows RFC2401 */ 268 sav = KEY_LOOKUP_SA(&dst_address, sproto, spi, sport, dport); 269 if (sav == NULL) { 270 IPSECLOG(LOG_DEBUG, 271 "no key association found for SA %s/%08lx/%u/%u\n", 272 ipsec_address(&dst_address, buf, sizeof(buf)), 273 (u_long) ntohl(spi), sproto, ntohs(dport)); 274 IPSEC_ISTAT(sproto, ESP_STAT_NOTDB, AH_STAT_NOTDB, 275 IPCOMP_STAT_NOTDB); 276 splx(s); 277 m_freem(m); 278 return ENOENT; 279 } 280 281 KASSERT(sav->tdb_xform != NULL); 282 283 /* 284 * Call appropriate transform and return -- callback takes care of 285 * everything else. 286 */ 287 error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff); 288 KEY_SA_UNREF(&sav); 289 splx(s); 290 return error; 291 } 292 293 #ifdef INET 294 /* 295 * Common input handler for IPv4 AH, ESP, and IPCOMP. 296 */ 297 void 298 ipsec4_common_input(struct mbuf *m, ...) 299 { 300 va_list ap; 301 int off, nxt; 302 303 va_start(ap, m); 304 off = va_arg(ap, int); 305 nxt = va_arg(ap, int); 306 va_end(ap); 307 308 (void)ipsec_common_input(m, off, offsetof(struct ip, ip_p), 309 AF_INET, nxt); 310 } 311 312 /* 313 * IPsec input callback for INET protocols. 314 * This routine is called as the transform callback. 315 * Takes care of filtering and other sanity checks on 316 * the processed packet. 317 */ 318 int 319 ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav, 320 int skip, int protoff) 321 { 322 int prot, af __diagused, sproto; 323 struct ip *ip; 324 struct secasindex *saidx; 325 int error; 326 327 if (__predict_false(m == NULL)) { 328 panic("%s: NULL mbuf", __func__); 329 } 330 if (__predict_false(skip < sizeof(struct ip))) { 331 panic("%s: short skip", __func__); 332 } 333 334 KASSERT(sav != NULL); 335 saidx = &sav->sah->saidx; 336 af = saidx->dst.sa.sa_family; 337 KASSERTMSG(af == AF_INET, "unexpected af %u", af); 338 sproto = saidx->proto; 339 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || 340 sproto == IPPROTO_IPCOMP, 341 "unexpected security protocol %u", sproto); 342 343 /* 344 * Update the IPv4 header. The length of the packet may have changed, 345 * so fix it, and recompute the checksum. 346 */ 347 if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) { 348 char buf[IPSEC_ADDRSTRLEN]; 349 cantpull: 350 IPSECLOG(LOG_DEBUG, 351 "processing failed for SA %s/%08lx\n", 352 ipsec_address(&sav->sah->saidx.dst, buf, 353 sizeof(buf)), (u_long) ntohl(sav->spi)); 354 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 355 IPCOMP_STAT_HDROPS); 356 error = ENOBUFS; 357 goto bad; 358 } 359 ip = mtod(m, struct ip *); 360 ip->ip_len = htons(m->m_pkthdr.len); 361 ip->ip_sum = 0; 362 ip->ip_sum = in_cksum(m, ip->ip_hl << 2); 363 364 /* 365 * Update TCP/UDP checksum 366 * XXX: should only do it in NAT-T case 367 * XXX: should do it incrementally, see FreeBSD code. 368 */ 369 m = ipsec4_fixup_checksum(m); 370 if (m == NULL) 371 goto cantpull; 372 ip = mtod(m, struct ip *); 373 374 prot = ip->ip_p; 375 376 M_VERIFY_PACKET(m); 377 378 key_sa_recordxfer(sav, m); 379 380 if ((inetsw[ip_protox[prot]].pr_flags & PR_LASTHDR) != 0 && 381 ipsec_in_reject(m, NULL)) { 382 error = EINVAL; 383 goto bad; 384 } 385 (*inetsw[ip_protox[prot]].pr_input)(m, skip, prot); 386 return 0; 387 388 bad: 389 m_freem(m); 390 return error; 391 } 392 #endif /* INET */ 393 394 #ifdef INET6 395 int 396 ipsec6_common_input(struct mbuf **mp, int *offp, int proto) 397 { 398 int l = 0; 399 int protoff, nxt; 400 struct ip6_ext ip6e; 401 402 if (*offp < sizeof(struct ip6_hdr)) { 403 IPSECLOG(LOG_DEBUG, "bad offset %u\n", *offp); 404 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 405 IPCOMP_STAT_HDROPS); 406 m_freem(*mp); 407 return IPPROTO_DONE; 408 } else if (*offp == sizeof(struct ip6_hdr)) { 409 protoff = offsetof(struct ip6_hdr, ip6_nxt); 410 } else { 411 /* Chase down the header chain... */ 412 protoff = sizeof(struct ip6_hdr); 413 nxt = (mtod(*mp, struct ip6_hdr *))->ip6_nxt; 414 415 do { 416 protoff += l; 417 m_copydata(*mp, protoff, sizeof(ip6e), &ip6e); 418 419 if (nxt == IPPROTO_AH) 420 l = (ip6e.ip6e_len + 2) << 2; 421 else if (nxt == IPPROTO_FRAGMENT) 422 l = sizeof(struct ip6_frag); 423 else 424 l = (ip6e.ip6e_len + 1) << 3; 425 KASSERT(l > 0); 426 427 nxt = ip6e.ip6e_nxt; 428 } while (protoff + l < *offp); 429 430 /* Malformed packet check */ 431 if (protoff + l != *offp) { 432 IPSECLOG(LOG_DEBUG, "bad packet header chain, " 433 "protoff %u, l %u, off %u\n", protoff, l, *offp); 434 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, 435 AH_STAT_HDROPS, 436 IPCOMP_STAT_HDROPS); 437 m_freem(*mp); 438 *mp = NULL; 439 return IPPROTO_DONE; 440 } 441 protoff += offsetof(struct ip6_ext, ip6e_nxt); 442 } 443 (void) ipsec_common_input(*mp, *offp, protoff, AF_INET6, proto); 444 return IPPROTO_DONE; 445 } 446 447 /* 448 * IPsec input callback, called by the transform callback. Takes care of 449 * filtering and other sanity checks on the processed packet. 450 */ 451 int 452 ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip, 453 int protoff) 454 { 455 int af __diagused, sproto; 456 struct ip6_hdr *ip6; 457 struct secasindex *saidx; 458 int nxt; 459 u_int8_t prot; 460 int error, nest; 461 462 if (__predict_false(m == NULL)) { 463 panic("%s: NULL mbuf", __func__); 464 } 465 466 KASSERT(sav != NULL); 467 saidx = &sav->sah->saidx; 468 af = saidx->dst.sa.sa_family; 469 KASSERTMSG(af == AF_INET6, "unexpected af %u", af); 470 sproto = saidx->proto; 471 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || 472 sproto == IPPROTO_IPCOMP, 473 "unexpected security protocol %u", sproto); 474 475 /* Fix IPv6 header */ 476 if (m->m_len < sizeof(struct ip6_hdr) && 477 (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 478 char buf[IPSEC_ADDRSTRLEN]; 479 IPSECLOG(LOG_DEBUG, "processing failed for SA %s/%08lx\n", 480 ipsec_address(&sav->sah->saidx.dst, 481 buf, sizeof(buf)), (u_long) ntohl(sav->spi)); 482 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 483 IPCOMP_STAT_HDROPS); 484 error = EACCES; 485 goto bad; 486 } 487 488 ip6 = mtod(m, struct ip6_hdr *); 489 ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr)); 490 491 m_copydata(m, protoff, sizeof(prot), &prot); 492 493 key_sa_recordxfer(sav, m); 494 495 /* 496 * See the end of ip6_input for this logic. 497 * IPPROTO_IPV[46] case will be processed just like other ones 498 */ 499 nest = 0; 500 nxt = prot; 501 while (nxt != IPPROTO_DONE) { 502 if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) { 503 IP6_STATINC(IP6_STAT_TOOMANYHDR); 504 error = EINVAL; 505 goto bad; 506 } 507 508 M_VERIFY_PACKET(m); 509 510 /* 511 * Protection against faulty packet - there should be 512 * more sanity checks in header chain processing. 513 */ 514 if (m->m_pkthdr.len < skip) { 515 IP6_STATINC(IP6_STAT_TOOSHORT); 516 in6_ifstat_inc(m_get_rcvif_NOMPSAFE(m), 517 ifs6_in_truncated); 518 error = EINVAL; 519 goto bad; 520 } 521 522 /* 523 * Enforce IPsec policy checking if we are seeing last header. 524 * Note that we do not visit this with protocols with pcb layer 525 * code - like udp/tcp/raw ip. 526 */ 527 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 && 528 ipsec_in_reject(m, NULL)) { 529 error = EINVAL; 530 goto bad; 531 } 532 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt); 533 } 534 return 0; 535 536 bad: 537 if (m) 538 m_freem(m); 539 return error; 540 } 541 #endif /* INET6 */ 542
Indexes created Thu Sep 25 06:09:39 GMT 2025