ipsec_input.c revision 1.71
1 /* $NetBSD: ipsec_input.c,v 1.71 2018/09/14 05:09:51 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 1.71 2018/09/14 05:09:51 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 /* 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, int off, int proto) 299 { 300 (void)ipsec_common_input(m, off, offsetof(struct ip, ip_p), 301 AF_INET, proto); 302 } 303 304 /* 305 * IPsec input callback for INET protocols. 306 * This routine is called as the transform callback. 307 * Takes care of filtering and other sanity checks on 308 * the processed packet. 309 */ 310 int 311 ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav, 312 int skip, int protoff) 313 { 314 int prot, af __diagused, sproto; 315 struct ip *ip; 316 struct secasindex *saidx; 317 int error; 318 319 if (__predict_false(m == NULL)) { 320 panic("%s: NULL mbuf", __func__); 321 } 322 if (__predict_false(skip < sizeof(struct ip))) { 323 panic("%s: short skip", __func__); 324 } 325 326 KASSERT(sav != NULL); 327 saidx = &sav->sah->saidx; 328 af = saidx->dst.sa.sa_family; 329 KASSERTMSG(af == AF_INET, "unexpected af %u", af); 330 sproto = saidx->proto; 331 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || 332 sproto == IPPROTO_IPCOMP, 333 "unexpected security protocol %u", sproto); 334 335 /* 336 * Update the IPv4 header. The length of the packet may have changed, 337 * so fix it, and recompute the checksum. 338 */ 339 if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) { 340 char buf[IPSEC_ADDRSTRLEN]; 341 cantpull: 342 IPSECLOG(LOG_DEBUG, 343 "processing failed for SA %s/%08lx\n", 344 ipsec_address(&sav->sah->saidx.dst, buf, 345 sizeof(buf)), (u_long) ntohl(sav->spi)); 346 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 347 IPCOMP_STAT_HDROPS); 348 error = ENOBUFS; 349 goto bad; 350 } 351 ip = mtod(m, struct ip *); 352 ip->ip_len = htons(m->m_pkthdr.len); 353 ip->ip_sum = 0; 354 ip->ip_sum = in_cksum(m, ip->ip_hl << 2); 355 356 /* 357 * Update TCP/UDP checksum 358 * XXX: should only do it in NAT-T case 359 * XXX: should do it incrementally, see FreeBSD code. 360 */ 361 m = ipsec4_fixup_checksum(m); 362 if (m == NULL) 363 goto cantpull; 364 ip = mtod(m, struct ip *); 365 366 prot = ip->ip_p; 367 368 M_VERIFY_PACKET(m); 369 370 key_sa_recordxfer(sav, m); 371 372 if ((inetsw[ip_protox[prot]].pr_flags & PR_LASTHDR) != 0 && 373 ipsec_in_reject(m, NULL)) { 374 error = EINVAL; 375 goto bad; 376 } 377 (*inetsw[ip_protox[prot]].pr_input)(m, skip, prot); 378 return 0; 379 380 bad: 381 m_freem(m); 382 return error; 383 } 384 #endif /* INET */ 385 386 #ifdef INET6 387 int 388 ipsec6_common_input(struct mbuf **mp, int *offp, int proto) 389 { 390 int l = 0; 391 int protoff, nxt; 392 struct ip6_ext ip6e; 393 394 if (*offp < sizeof(struct ip6_hdr)) { 395 IPSECLOG(LOG_DEBUG, "bad offset %u\n", *offp); 396 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 397 IPCOMP_STAT_HDROPS); 398 m_freem(*mp); 399 return IPPROTO_DONE; 400 } else if (*offp == sizeof(struct ip6_hdr)) { 401 protoff = offsetof(struct ip6_hdr, ip6_nxt); 402 } else { 403 /* Chase down the header chain... */ 404 protoff = sizeof(struct ip6_hdr); 405 nxt = (mtod(*mp, struct ip6_hdr *))->ip6_nxt; 406 407 do { 408 protoff += l; 409 m_copydata(*mp, protoff, sizeof(ip6e), &ip6e); 410 411 if (nxt == IPPROTO_AH) 412 l = (ip6e.ip6e_len + 2) << 2; 413 else if (nxt == IPPROTO_FRAGMENT) 414 l = sizeof(struct ip6_frag); 415 else 416 l = (ip6e.ip6e_len + 1) << 3; 417 KASSERT(l > 0); 418 419 nxt = ip6e.ip6e_nxt; 420 } while (protoff + l < *offp); 421 422 /* Malformed packet check */ 423 if (protoff + l != *offp) { 424 IPSECLOG(LOG_DEBUG, "bad packet header chain, " 425 "protoff %u, l %u, off %u\n", protoff, l, *offp); 426 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, 427 AH_STAT_HDROPS, 428 IPCOMP_STAT_HDROPS); 429 m_freem(*mp); 430 *mp = NULL; 431 return IPPROTO_DONE; 432 } 433 protoff += offsetof(struct ip6_ext, ip6e_nxt); 434 } 435 (void) ipsec_common_input(*mp, *offp, protoff, AF_INET6, proto); 436 return IPPROTO_DONE; 437 } 438 439 /* 440 * IPsec input callback, called by the transform callback. Takes care of 441 * filtering and other sanity checks on the processed packet. 442 */ 443 int 444 ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip, 445 int protoff) 446 { 447 int af __diagused, sproto; 448 struct ip6_hdr *ip6; 449 struct secasindex *saidx; 450 int nxt; 451 u_int8_t prot; 452 int error, nest; 453 454 if (__predict_false(m == NULL)) { 455 panic("%s: NULL mbuf", __func__); 456 } 457 458 KASSERT(sav != NULL); 459 saidx = &sav->sah->saidx; 460 af = saidx->dst.sa.sa_family; 461 KASSERTMSG(af == AF_INET6, "unexpected af %u", af); 462 sproto = saidx->proto; 463 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || 464 sproto == IPPROTO_IPCOMP, 465 "unexpected security protocol %u", sproto); 466 467 /* Fix IPv6 header */ 468 if (m->m_len < sizeof(struct ip6_hdr) && 469 (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 470 char buf[IPSEC_ADDRSTRLEN]; 471 IPSECLOG(LOG_DEBUG, "processing failed for SA %s/%08lx\n", 472 ipsec_address(&sav->sah->saidx.dst, 473 buf, sizeof(buf)), (u_long) ntohl(sav->spi)); 474 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, 475 IPCOMP_STAT_HDROPS); 476 error = EACCES; 477 goto bad; 478 } 479 480 ip6 = mtod(m, struct ip6_hdr *); 481 ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr)); 482 483 m_copydata(m, protoff, sizeof(prot), &prot); 484 485 key_sa_recordxfer(sav, m); 486 487 /* 488 * See the end of ip6_input for this logic. 489 * IPPROTO_IPV[46] case will be processed just like other ones 490 */ 491 nest = 0; 492 nxt = prot; 493 while (nxt != IPPROTO_DONE) { 494 if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) { 495 IP6_STATINC(IP6_STAT_TOOMANYHDR); 496 error = EINVAL; 497 goto bad; 498 } 499 500 M_VERIFY_PACKET(m); 501 502 /* 503 * Protection against faulty packet - there should be 504 * more sanity checks in header chain processing. 505 */ 506 if (m->m_pkthdr.len < skip) { 507 IP6_STATINC(IP6_STAT_TOOSHORT); 508 in6_ifstat_inc(m_get_rcvif_NOMPSAFE(m), 509 ifs6_in_truncated); 510 error = EINVAL; 511 goto bad; 512 } 513 514 /* 515 * Enforce IPsec policy checking if we are seeing last header. 516 * Note that we do not visit this with protocols with pcb layer 517 * code - like udp/tcp/raw ip. 518 */ 519 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 && 520 ipsec_in_reject(m, NULL)) { 521 error = EINVAL; 522 goto bad; 523 } 524 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt); 525 } 526 return 0; 527 528 bad: 529 if (m) 530 m_freem(m); 531 return error; 532 } 533 #endif /* INET6 */ 534
Indexes created Sat Sep 27 21:09:56 GMT 2025