sys/netinet/ip_ipsec.c

   1 /*-
   2  * Copyright (c) 1982, 1986, 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD$
  30  */
  31
  32 #include "opt_ipsec.h"
  33
  34 #include <sys/param.h>
  35 #include <sys/systm.h>
  36 #include <sys/kernel.h>
  37 #include <sys/malloc.h>
  38 #include <sys/mbuf.h>
  39 #include <sys/protosw.h>
  40 #include <sys/socket.h>
  41 #include <sys/socketvar.h>
  42 #include <sys/sysctl.h>
  43
  44 #include <net/if.h>
  45 #include <net/route.h>
  46
  47 #include <netinet/in.h>
  48 #include <netinet/in_systm.h>
  49 #include <netinet/in_var.h>
  50 #include <netinet/ip.h>
  51 #include <netinet/in_pcb.h>
  52 #include <netinet/ip_var.h>
  53 #include <netinet/ip_options.h>
  54 #include <netinet/ip_ipsec.h>
  55
  56 #include <machine/in_cksum.h>
  57
  58 #ifdef IPSEC
  59 #include <netinet6/ipsec.h>
  60 #include <netkey/key.h>
  61 #ifdef IPSEC_DEBUG
  62 #include <netkey/key_debug.h>
  63 #else
  64 #define KEYDEBUG(lev,arg)
  65 #endif
  66 #endif /*IPSEC*/
  67
  68 #ifdef FAST_IPSEC
  69 #include <netipsec/ipsec.h>
  70 #include <netipsec/xform.h>
  71 #include <netipsec/key.h>
  72 #endif /*FAST_IPSEC*/
  73
  74 extern  struct protosw inetsw[];
  75
  76 /*
  77  * Check if we have to jump over firewall processing for this packet.
  78  * Called from ip_input().
  79  * 1 = jump over firewall, 0 = packet goes through firewall.
  80  */
  81 int
  82 ip_ipsec_filtergif(struct mbuf *m)
  83 {
  84 #if defined(IPSEC) && !defined(IPSEC_FILTERGIF)
  85         /*
  86          * Bypass packet filtering for packets from a tunnel (gif).
  87          */
  88         if (ipsec_getnhist(m))
  89                 return 1;
  90 #endif
  91 #if defined(FAST_IPSEC) && !defined(IPSEC_FILTERGIF)
  92         /*
  93          * Bypass packet filtering for packets from a tunnel (gif).
  94          */
  95         if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  96                 return 1;
  97 #endif
  98         return 0;
  99 }
 100
 101 /*
 102  * Check if this packet has an active SA and needs to be dropped instead
 103  * of forwarded.
 104  * Called from ip_input().
 105  * 1 = drop packet, 0 = forward packet.
 106  */
 107 int
 108 ip_ipsec_fwd(struct mbuf *m)
 109 {
 110 #ifdef FAST_IPSEC
 111         struct m_tag *mtag;
 112         struct tdb_ident *tdbi;
 113         struct secpolicy *sp;
 114         int s, error;
 115 #endif /* FAST_IPSEC */
 116 #ifdef IPSEC
 117         /*
 118          * Enforce inbound IPsec SPD.
 119          */
 120         if (ipsec4_in_reject(m, NULL)) {
 121                 ipsecstat.in_polvio++;
 122                 return 1;
 123         }
 124 #endif /* IPSEC */
 125 #ifdef FAST_IPSEC
 126         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 127         s = splnet();
 128         if (mtag != NULL) {
 129                 tdbi = (struct tdb_ident *)(mtag + 1);
 130                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 131         } else {
 132                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 133                                            IP_FORWARDING, &error);
 134         }
 135         if (sp == NULL) {       /* NB: can happen if error */
 136                 splx(s);
 137                 /*XXX error stat???*/
 138                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 139                 return 1;
 140         }
 141
 142         /*
 143          * Check security policy against packet attributes.
 144          */
 145         error = ipsec_in_reject(sp, m);
 146         KEY_FREESP(&sp);
 147         splx(s);
 148         if (error) {
 149                 ipstat.ips_cantforward++;
 150                 return 1;
 151         }
 152 #endif /* FAST_IPSEC */
 153         return 0;
 154 }
 155
 156 /*
 157  * Check if protocol type doesn't have a further header and do IPSEC
 158  * decryption or reject right now.  Protocols with further headers get
 159  * their IPSEC treatment within the protocol specific processing.
 160  * Called from ip_input().
 161  * 1 = drop packet, 0 = continue processing packet.
 162  */
 163 int
 164 ip_ipsec_input(struct mbuf *m)
 165 {
 166         struct ip *ip = mtod(m, struct ip *);
 167 #ifdef FAST_IPSEC
 168         struct m_tag *mtag;
 169         struct tdb_ident *tdbi;
 170         struct secpolicy *sp;
 171         int s, error;
 172 #endif /* FAST_IPSEC */
 173 #ifdef IPSEC
 174         /*
 175          * enforce IPsec policy checking if we are seeing last header.
 176          * note that we do not visit this with protocols with pcb layer
 177          * code - like udp/tcp/raw ip.
 178          */
 179         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
 180             ipsec4_in_reject(m, NULL)) {
 181                 ipsecstat.in_polvio++;
 182                 return 1;
 183         }
 184 #endif
 185 #ifdef FAST_IPSEC
 186         /*
 187          * enforce IPsec policy checking if we are seeing last header.
 188          * note that we do not visit this with protocols with pcb layer
 189          * code - like udp/tcp/raw ip.
 190          */
 191         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 192                 /*
 193                  * Check if the packet has already had IPsec processing
 194                  * done.  If so, then just pass it along.  This tag gets
 195                  * set during AH, ESP, etc. input handling, before the
 196                  * packet is returned to the ip input queue for delivery.
 197                  */
 198                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 199                 s = splnet();
 200                 if (mtag != NULL) {
 201                         tdbi = (struct tdb_ident *)(mtag + 1);
 202                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 203                 } else {
 204                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 205                                                    IP_FORWARDING, &error);
 206                 }
 207                 if (sp != NULL) {
 208                         /*
 209                          * Check security policy against packet attributes.
 210                          */
 211                         error = ipsec_in_reject(sp, m);
 212                         KEY_FREESP(&sp);
 213                 } else {
 214                         /* XXX error stat??? */
 215                         error = EINVAL;
 216                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 217                         return 1;
 218                 }
 219                 splx(s);
 220                 if (error)
 221                         return 1;
 222         }
 223 #endif /* FAST_IPSEC */
 224         return 0;
 225 }
 226
 227 /*
 228  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 229  * Called from ip_forward().
 230  * Returns MTU suggestion for ICMP needfrag reply.
 231  */
 232 int
 233 ip_ipsec_mtu(struct mbuf *m)
 234 {
 235         int mtu = 0;
 236         /*
 237          * If the packet is routed over IPsec tunnel, tell the
 238          * originator the tunnel MTU.
 239          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 240          * XXX quickhack!!!
 241          */
 242         struct secpolicy *sp = NULL;
 243         int ipsecerror;
 244         int ipsechdr;
 245         struct route *ro;
 246 #ifdef IPSEC
 247         sp = ipsec4_getpolicybyaddr(m,
 248                                     IPSEC_DIR_OUTBOUND,
 249                                     IP_FORWARDING,
 250                                     &ipsecerror);
 251 #else /* FAST_IPSEC */
 252         sp = ipsec_getpolicybyaddr(m,
 253                                    IPSEC_DIR_OUTBOUND,
 254                                    IP_FORWARDING,
 255                                    &ipsecerror);
 256 #endif
 257         if (sp != NULL) {
 258                 /* count IPsec header size */
 259                 ipsechdr = ipsec4_hdrsiz(m,
 260                                          IPSEC_DIR_OUTBOUND,
 261                                          NULL);
 262
 263                 /*
 264                  * find the correct route for outer IPv4
 265                  * header, compute tunnel MTU.
 266                  */
 267                 if (sp->req != NULL &&
 268                     sp->req->sav != NULL &&
 269                     sp->req->sav->sah != NULL) {
 270                         ro = &sp->req->sav->sah->sa_route;
 271                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 272                                 mtu =
 273                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 274                                     ro->ro_rt->rt_rmx.rmx_mtu :
 275                                     ro->ro_rt->rt_ifp->if_mtu;
 276                                 mtu -= ipsechdr;
 277                         }
 278                 }
 279 #ifdef IPSEC
 280                 key_freesp(sp);
 281 #else /* FAST_IPSEC */
 282                 KEY_FREESP(&sp);
 283 #endif
 284         }
 285         return mtu;
 286 }
 287
 288 /*
 289  *
 290  * Called from ip_output().
 291  * 1 = drop packet, 0 = continue processing packet,
 292  * -1 = packet was reinjected and stop processing packet (FAST_IPSEC only)
 293  */
 294 int
 295 ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 296              struct route **ro, struct route *iproute, struct sockaddr_in **dst,
 297              struct in_ifaddr **ia, struct ifnet **ifp)
 298 {
 299         struct secpolicy *sp = NULL;
 300         struct ip *ip = mtod(*m, struct ip *);
 301 #ifdef IPSEC
 302         struct ipsec_output_state state;
 303 #endif
 304 #ifdef FAST_IPSEC
 305         struct tdb_ident *tdbi;
 306         struct m_tag *mtag;
 307         int s;
 308 #endif /* FAST_IPSEC */
 309 #ifdef IPSEC
 310         /* get SP for this packet */
 311         if (inp == NULL)
 312                 sp = ipsec4_getpolicybyaddr(*m, IPSEC_DIR_OUTBOUND,
 313                     *flags, error);
 314         else
 315                 sp = ipsec4_getpolicybypcb(*m, IPSEC_DIR_OUTBOUND, inp, error);
 316
 317         if (sp == NULL) {
 318                 ipsecstat.out_inval++;
 319                 goto bad;
 320         }
 321
 322         /* check policy */
 323         switch (sp->policy) {
 324         case IPSEC_POLICY_DISCARD:
 325                 /*
 326                  * This packet is just discarded.
 327                  */
 328                 ipsecstat.out_polvio++;
 329                 goto bad;
 330
 331         case IPSEC_POLICY_BYPASS:
 332         case IPSEC_POLICY_NONE:
 333         case IPSEC_POLICY_TCP:
 334                 /* no need to do IPsec. */
 335                 goto done;
 336
 337         case IPSEC_POLICY_IPSEC:
 338                 if (sp->req == NULL) {
 339                         /* acquire a policy */
 340                         *error = key_spdacquire(sp);
 341                         goto bad;
 342                 }
 343                 break;
 344
 345         case IPSEC_POLICY_ENTRUST:
 346         default:
 347                 printf("%s: Invalid policy found. %d\n", __func__, sp->policy);
 348         }
 349
 350         bzero(&state, sizeof(state));
 351         state.m = *m;
 352         if (*flags & IP_ROUTETOIF) {
 353                 state.ro = iproute;
 354                 bzero(iproute, sizeof(iproute));
 355         } else
 356                 state.ro = *ro;
 357         state.dst = (struct sockaddr *)(*dst);
 358
 359         ip->ip_sum = 0;
 360
 361         /*
 362          * XXX
 363          * delayed checksums are not currently compatible with IPsec
 364          */
 365         if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 366                 in_delayed_cksum(*m);
 367                 (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 368         }
 369
 370         ip->ip_len = htons(ip->ip_len);
 371         ip->ip_off = htons(ip->ip_off);
 372
 373         *error = ipsec4_output(&state, sp, *flags);
 374
 375         *m = state.m;
 376         if (*flags & IP_ROUTETOIF) {
 377                 /*
 378                  * if we have tunnel mode SA, we may need to ignore
 379                  * IP_ROUTETOIF.
 380                  */
 381                 if (state.ro != iproute || state.ro->ro_rt != NULL) {
 382                         *flags &= ~IP_ROUTETOIF;
 383                         *ro = state.ro;
 384                 }
 385         } else
 386                 *ro = state.ro;
 387         *dst = (struct sockaddr_in *)state.dst;
 388         if (*error != 0) {
 389                 /* mbuf is already reclaimed in ipsec4_output. */
 390                 *m = NULL;
 391                 switch (*error) {
 392                 case EHOSTUNREACH:
 393                 case ENETUNREACH:
 394                 case EMSGSIZE:
 395                 case ENOBUFS:
 396                 case ENOMEM:
 397                         break;
 398                 default:
 399                         printf("ip4_output (ipsec): error code %d\n", *error);
 400                         /*fall through*/
 401                 case ENOENT:
 402                         /* don't show these error codes to the user */
 403                         *error = 0;
 404                         break;
 405                 }
 406                 goto bad;
 407         }
 408
 409         /* be sure to update variables that are affected by ipsec4_output() */
 410         if ((*ro)->ro_rt == NULL) {
 411                 if ((*flags & IP_ROUTETOIF) == 0) {
 412                         printf("ip_output: "
 413                                 "can't update route after IPsec processing\n");
 414                         *error = EHOSTUNREACH;  /*XXX*/
 415                         goto bad;
 416                 }
 417         } else {
 418                 if (state.encap) {
 419                         *ia = ifatoia((*ro)->ro_rt->rt_ifa);
 420                         *ifp = (*ro)->ro_rt->rt_ifp;
 421                 }
 422         }
 423         ip = mtod(*m, struct ip *);
 424
 425         /* make it flipped, again. */
 426         ip->ip_len = ntohs(ip->ip_len);
 427         ip->ip_off = ntohs(ip->ip_off);
 428
 429 done:
 430         if (sp != NULL) {
 431                 KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
 432                         printf("DP ip_output call free SP:%p\n", sp));
 433                 key_freesp(sp);
 434         }
 435         return 0;
 436 bad:
 437         if (sp != NULL) {
 438                 KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
 439                         printf("DP ip_output call free SP:%p\n", sp));
 440                 key_freesp(sp);
 441         }
 442         return 1;
 443 #endif /*IPSEC*/
 444 #ifdef FAST_IPSEC
 445         /*
 446          * Check the security policy (SP) for the packet and, if
 447          * required, do IPsec-related processing.  There are two
 448          * cases here; the first time a packet is sent through
 449          * it will be untagged and handled by ipsec4_checkpolicy.
 450          * If the packet is resubmitted to ip_output (e.g. after
 451          * AH, ESP, etc. processing), there will be a tag to bypass
 452          * the lookup and related policy checking.
 453          */
 454         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 455         s = splnet();
 456         if (mtag != NULL) {
 457                 tdbi = (struct tdb_ident *)(mtag + 1);
 458                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 459                 if (sp == NULL)
 460                         *error = -EINVAL;       /* force silent drop */
 461                 m_tag_delete(*m, mtag);
 462         } else {
 463                 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 464                                         error, inp);
 465         }
 466         /*
 467          * There are four return cases:
 468          *    sp != NULL                    apply IPsec policy
 469          *    sp == NULL, error == 0        no IPsec handling needed
 470          *    sp == NULL, error == -EINVAL  discard packet w/o error
 471          *    sp == NULL, error != 0        discard packet, report error
 472          */
 473         if (sp != NULL) {
 474                 /* Loop detection, check if ipsec processing already done */
 475                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
 476                 for (mtag = m_tag_first(*m); mtag != NULL;
 477                      mtag = m_tag_next(*m, mtag)) {
 478                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 479                                 continue;
 480                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 481                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 482                                 continue;
 483                         /*
 484                          * Check if policy has an SA associated with it.
 485                          * This can happen when an SP has yet to acquire
 486                          * an SA; e.g. on first reference.  If it occurs,
 487                          * then we let ipsec4_process_packet do its thing.
 488                          */
 489                         if (sp->req->sav == NULL)
 490                                 break;
 491                         tdbi = (struct tdb_ident *)(mtag + 1);
 492                         if (tdbi->spi == sp->req->sav->spi &&
 493                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
 494                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
 495                                  sizeof (union sockaddr_union)) == 0) {
 496                                 /*
 497                                  * No IPsec processing is needed, free
 498                                  * reference to SP.
 499                                  *
 500                                  * NB: null pointer to avoid free at
 501                                  *     done: below.
 502                                  */
 503                                 KEY_FREESP(&sp), sp = NULL;
 504                                 splx(s);
 505                                 goto done;
 506                         }
 507                 }
 508
 509                 /*
 510                  * Do delayed checksums now because we send before
 511                  * this is done in the normal processing path.
 512                  */
 513                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 514                         in_delayed_cksum(*m);
 515                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 516                 }
 517
 518                 ip->ip_len = htons(ip->ip_len);
 519                 ip->ip_off = htons(ip->ip_off);
 520
 521                 /* NB: callee frees mbuf */
 522                 *error = ipsec4_process_packet(*m, sp->req, *flags, 0);
 523                 /*
 524                  * Preserve KAME behaviour: ENOENT can be returned
 525                  * when an SA acquire is in progress.  Don't propagate
 526                  * this to user-level; it confuses applications.
 527                  *
 528                  * XXX this will go away when the SADB is redone.
 529                  */
 530                 if (*error == ENOENT)
 531                         *error = 0;
 532                 splx(s);
 533                 goto reinjected;
 534         } else {        /* sp == NULL */
 535                 splx(s);
 536
 537                 if (*error != 0) {
 538                         /*
 539                          * Hack: -EINVAL is used to signal that a packet
 540                          * should be silently discarded.  This is typically
 541                          * because we asked key management for an SA and
 542                          * it was delayed (e.g. kicked up to IKE).
 543                          */
 544                         if (*error == -EINVAL)
 545                                 *error = 0;
 546                         goto bad;
 547                 } else {
 548                         /* No IPsec processing for this packet. */
 549                 }
 550 #ifdef notyet
 551                 /*
 552                  * If deferred crypto processing is needed, check that
 553                  * the interface supports it.
 554                  */
 555                 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED, NULL);
 556                 if (mtag != NULL && ((*ifp)->if_capenable & IFCAP_IPSEC) == 0) {
 557                         /* notify IPsec to do its own crypto */
 558                         ipsp_skipcrypto_unmark((struct tdb_ident *)(mtag + 1));
 559                         *error = EHOSTUNREACH;
 560                         goto bad;
 561                 }
 562 #endif
 563         }
 564 done:
 565         if (sp != NULL)
 566                 KEY_FREESP(&sp);
 567         return 0;
 568 reinjected:
 569         if (sp != NULL)
 570                 KEY_FREESP(&sp);
 571         return -1;
 572 bad:
 573         if (sp != NULL)
 574                 KEY_FREESP(&sp);
 575         return 1;
 576 #endif /* FAST_IPSEC */
 577         return 0;
 578 }
 579