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/mac.h>
  38 #include <sys/malloc.h>
  39 #include <sys/mbuf.h>
  40 #include <sys/protosw.h>
  41 #include <sys/socket.h>
  42 #include <sys/socketvar.h>
  43 #include <sys/sysctl.h>
  44
  45 #include <net/if.h>
  46 #include <net/route.h>
  47
  48 #include <netinet/in.h>
  49 #include <netinet/in_systm.h>
  50 #include <netinet/in_var.h>
  51 #include <netinet/ip.h>
  52 #include <netinet/in_pcb.h>
  53 #include <netinet/ip_var.h>
  54 #include <netinet/ip_options.h>
  55 #include <netinet/ip_ipsec.h>
  56
  57 #include <machine/in_cksum.h>
  58
  59 #ifdef IPSEC
  60 #include <netinet6/ipsec.h>
  61 #include <netkey/key.h>
  62 #ifdef IPSEC_DEBUG
  63 #include <netkey/key_debug.h>
  64 #else
  65 #define KEYDEBUG(lev,arg)
  66 #endif
  67 #endif /*IPSEC*/
  68
  69 #ifdef FAST_IPSEC
  70 #include <netipsec/ipsec.h>
  71 #include <netipsec/xform.h>
  72 #include <netipsec/key.h>
  73 #endif /*FAST_IPSEC*/
  74
  75 extern  struct protosw inetsw[];
  76
  77 /*
  78  * Check if we have to jump over firewall processing for this packet.
  79  * Called from ip_input().
  80  * 1 = jump over firewall, 0 = packet goes through firewall.
  81  */
  82 int
  83 ip_ipsec_filtergif(struct mbuf *m)
  84 {
  85 #if defined(IPSEC) && !defined(IPSEC_FILTERGIF)
  86         /*
  87          * Bypass packet filtering for packets from a tunnel (gif).
  88          */
  89         if (ipsec_getnhist(m))
  90                 return 1;
  91 #endif
  92 #if defined(FAST_IPSEC) && !defined(IPSEC_FILTERGIF)
  93         /*
  94          * Bypass packet filtering for packets from a tunnel (gif).
  95          */
  96         if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  97                 return 1;
  98 #endif
  99         return 0;
 100 }
 101
 102 /*
 103  * Check if this packet has an active SA and needs to be dropped instead
 104  * of forwarded.
 105  * Called from ip_input().
 106  * 1 = drop packet, 0 = forward packet.
 107  */
 108 int
 109 ip_ipsec_fwd(struct mbuf *m)
 110 {
 111 #ifdef FAST_IPSEC
 112         struct m_tag *mtag;
 113         struct tdb_ident *tdbi;
 114         struct secpolicy *sp;
 115         int s, error;
 116 #endif /* FAST_IPSEC */
 117 #ifdef IPSEC
 118         /*
 119          * Enforce inbound IPsec SPD.
 120          */
 121         if (ipsec4_in_reject(m, NULL)) {
 122                 ipsecstat.in_polvio++;
 123                 return 1;
 124         }
 125 #endif /* IPSEC */
 126 #ifdef FAST_IPSEC
 127         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 128         s = splnet();
 129         if (mtag != NULL) {
 130                 tdbi = (struct tdb_ident *)(mtag + 1);
 131                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 132         } else {
 133                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 134                                            IP_FORWARDING, &error);
 135         }
 136         if (sp == NULL) {       /* NB: can happen if error */
 137                 splx(s);
 138                 /*XXX error stat???*/
 139                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 140                 return 1;
 141         }
 142
 143         /*
 144          * Check security policy against packet attributes.
 145          */
 146         error = ipsec_in_reject(sp, m);
 147         KEY_FREESP(&sp);
 148         splx(s);
 149         if (error) {
 150                 ipstat.ips_cantforward++;
 151                 return 1;
 152         }
 153 #endif /* FAST_IPSEC */
 154         return 0;
 155 }
 156
 157 /*
 158  * Check if protocol type doesn't have a further header and do IPSEC
 159  * decryption or reject right now.  Protocols with further headers get
 160  * their IPSEC treatment within the protocol specific processing.
 161  * Called from ip_input().
 162  * 1 = drop packet, 0 = continue processing packet.
 163  */
 164 int
 165 ip_ipsec_input(struct mbuf *m)
 166 {
 167         struct ip *ip = mtod(m, struct ip *);
 168 #ifdef FAST_IPSEC
 169         struct m_tag *mtag;
 170         struct tdb_ident *tdbi;
 171         struct secpolicy *sp;
 172         int s, error;
 173 #endif /* FAST_IPSEC */
 174 #ifdef IPSEC
 175         /*
 176          * enforce IPsec policy checking if we are seeing last header.
 177          * note that we do not visit this with protocols with pcb layer
 178          * code - like udp/tcp/raw ip.
 179          */
 180         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
 181             ipsec4_in_reject(m, NULL)) {
 182                 ipsecstat.in_polvio++;
 183                 return 1;
 184         }
 185 #endif
 186 #ifdef FAST_IPSEC
 187         /*
 188          * enforce IPsec policy checking if we are seeing last header.
 189          * note that we do not visit this with protocols with pcb layer
 190          * code - like udp/tcp/raw ip.
 191          */
 192         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 193                 /*
 194                  * Check if the packet has already had IPsec processing
 195                  * done.  If so, then just pass it along.  This tag gets
 196                  * set during AH, ESP, etc. input handling, before the
 197                  * packet is returned to the ip input queue for delivery.
 198                  */
 199                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 200                 s = splnet();
 201                 if (mtag != NULL) {
 202                         tdbi = (struct tdb_ident *)(mtag + 1);
 203                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 204                 } else {
 205                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 206                                                    IP_FORWARDING, &error);
 207                 }
 208                 if (sp != NULL) {
 209                         /*
 210                          * Check security policy against packet attributes.
 211                          */
 212                         error = ipsec_in_reject(sp, m);
 213                         KEY_FREESP(&sp);
 214                 } else {
 215                         /* XXX error stat??? */
 216                         error = EINVAL;
 217                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 218                         return 1;
 219                 }
 220                 splx(s);
 221                 if (error)
 222                         return 1;
 223         }
 224 #endif /* FAST_IPSEC */
 225         return 0;
 226 }
 227
 228 /*
 229  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 230  * Called from ip_forward().
 231  * Returns MTU suggestion for ICMP needfrag reply.
 232  */
 233 int
 234 ip_ipsec_mtu(struct mbuf *m)
 235 {
 236         int mtu = 0;
 237         /*
 238          * If the packet is routed over IPsec tunnel, tell the
 239          * originator the tunnel MTU.
 240          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 241          * XXX quickhack!!!
 242          */
 243         struct secpolicy *sp = NULL;
 244         int ipsecerror;
 245         int ipsechdr;
 246         struct route *ro;
 247 #ifdef IPSEC
 248         sp = ipsec4_getpolicybyaddr(m,
 249                                     IPSEC_DIR_OUTBOUND,
 250                                     IP_FORWARDING,
 251                                     &ipsecerror);
 252 #else /* FAST_IPSEC */
 253         sp = ipsec_getpolicybyaddr(m,
 254                                    IPSEC_DIR_OUTBOUND,
 255                                    IP_FORWARDING,
 256                                    &ipsecerror);
 257 #endif
 258         if (sp != NULL) {
 259                 /* count IPsec header size */
 260                 ipsechdr = ipsec4_hdrsiz(m,
 261                                          IPSEC_DIR_OUTBOUND,
 262                                          NULL);
 263
 264                 /*
 265                  * find the correct route for outer IPv4
 266                  * header, compute tunnel MTU.
 267                  */
 268                 if (sp->req != NULL &&
 269                     sp->req->sav != NULL &&
 270                     sp->req->sav->sah != NULL) {
 271                         ro = &sp->req->sav->sah->sa_route;
 272                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 273                                 mtu =
 274                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 275                                     ro->ro_rt->rt_rmx.rmx_mtu :
 276                                     ro->ro_rt->rt_ifp->if_mtu;
 277                                 mtu -= ipsechdr;
 278                         }
 279                 }
 280 #ifdef IPSEC
 281                 key_freesp(sp);
 282 #else /* FAST_IPSEC */
 283                 KEY_FREESP(&sp);
 284 #endif
 285         }
 286         return mtu;
 287 }
 288
 289 /*
 290  *
 291  * Called from ip_output().
 292  * 1 = drop packet, 0 = continue processing packet,
 293  * -1 = packet was reinjected and stop processing packet (FAST_IPSEC only)
 294  */
 295 int
 296 ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 297              struct route **ro, struct route *iproute, struct sockaddr_in **dst,
 298              struct in_ifaddr **ia, struct ifnet **ifp)
 299 {
 300         struct secpolicy *sp = NULL;
 301         struct ip *ip = mtod(*m, struct ip *);
 302 #ifdef IPSEC
 303         struct ipsec_output_state state;
 304 #endif
 305 #ifdef FAST_IPSEC
 306         struct tdb_ident *tdbi;
 307         struct m_tag *mtag;
 308         int s;
 309 #endif /* FAST_IPSEC */
 310 #ifdef IPSEC
 311         /* get SP for this packet */
 312         if (inp == NULL)
 313                 sp = ipsec4_getpolicybyaddr(*m, IPSEC_DIR_OUTBOUND,
 314                     *flags, error);
 315         else
 316                 sp = ipsec4_getpolicybypcb(*m, IPSEC_DIR_OUTBOUND, inp, error);
 317
 318         if (sp == NULL) {
 319                 ipsecstat.out_inval++;
 320                 goto bad;
 321         }
 322
 323         /* check policy */
 324         switch (sp->policy) {
 325         case IPSEC_POLICY_DISCARD:
 326                 /*
 327                  * This packet is just discarded.
 328                  */
 329                 ipsecstat.out_polvio++;
 330                 goto bad;
 331
 332         case IPSEC_POLICY_BYPASS:
 333         case IPSEC_POLICY_NONE:
 334         case IPSEC_POLICY_TCP:
 335                 /* no need to do IPsec. */
 336                 goto done;
 337
 338         case IPSEC_POLICY_IPSEC:
 339                 if (sp->req == NULL) {
 340                         /* acquire a policy */
 341                         *error = key_spdacquire(sp);
 342                         goto bad;
 343                 }
 344                 break;
 345
 346         case IPSEC_POLICY_ENTRUST:
 347         default:
 348                 printf("%s: Invalid policy found. %d\n", __func__, sp->policy);
 349         }
 350
 351         bzero(&state, sizeof(state));
 352         state.m = *m;
 353         if (*flags & IP_ROUTETOIF) {
 354                 state.ro = iproute;
 355                 bzero(iproute, sizeof(iproute));
 356         } else
 357                 state.ro = *ro;
 358         state.dst = (struct sockaddr *)(*dst);
 359
 360         ip->ip_sum = 0;
 361
 362         /*
 363          * XXX
 364          * delayed checksums are not currently compatible with IPsec
 365          */
 366         if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 367                 in_delayed_cksum(*m);
 368                 (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 369         }
 370
 371         ip->ip_len = htons(ip->ip_len);
 372         ip->ip_off = htons(ip->ip_off);
 373
 374         *error = ipsec4_output(&state, sp, *flags);
 375
 376         *m = state.m;
 377         if (*flags & IP_ROUTETOIF) {
 378                 /*
 379                  * if we have tunnel mode SA, we may need to ignore
 380                  * IP_ROUTETOIF.
 381                  */
 382                 if (state.ro != iproute || state.ro->ro_rt != NULL) {
 383                         *flags &= ~IP_ROUTETOIF;
 384                         *ro = state.ro;
 385                 }
 386         } else
 387                 *ro = state.ro;
 388         *dst = (struct sockaddr_in *)state.dst;
 389         if (*error != 0) {
 390                 /* mbuf is already reclaimed in ipsec4_output. */
 391                 *m = NULL;
 392                 switch (*error) {
 393                 case EHOSTUNREACH:
 394                 case ENETUNREACH:
 395                 case EMSGSIZE:
 396                 case ENOBUFS:
 397                 case ENOMEM:
 398                         break;
 399                 default:
 400                         printf("ip4_output (ipsec): error code %d\n", *error);
 401                         /*fall through*/
 402                 case ENOENT:
 403                         /* don't show these error codes to the user */
 404                         *error = 0;
 405                         break;
 406                 }
 407                 goto bad;
 408         }
 409
 410         /* be sure to update variables that are affected by ipsec4_output() */
 411         if ((*ro)->ro_rt == NULL) {
 412                 if ((*flags & IP_ROUTETOIF) == 0) {
 413                         printf("ip_output: "
 414                                 "can't update route after IPsec processing\n");
 415                         *error = EHOSTUNREACH;  /*XXX*/
 416                         goto bad;
 417                 }
 418         } else {
 419                 if (state.encap) {
 420                         *ia = ifatoia((*ro)->ro_rt->rt_ifa);
 421                         *ifp = (*ro)->ro_rt->rt_ifp;
 422                 }
 423         }
 424         ip = mtod(*m, struct ip *);
 425
 426         /* make it flipped, again. */
 427         ip->ip_len = ntohs(ip->ip_len);
 428         ip->ip_off = ntohs(ip->ip_off);
 429
 430 done:
 431         if (sp != NULL) {
 432                 KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
 433                         printf("DP ip_output call free SP:%p\n", sp));
 434                 key_freesp(sp);
 435         }
 436         return 0;
 437 bad:
 438         if (sp != NULL) {
 439                 KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
 440                         printf("DP ip_output call free SP:%p\n", sp));
 441                 key_freesp(sp);
 442         }
 443         return 1;
 444 #endif /*IPSEC*/
 445 #ifdef FAST_IPSEC
 446         /*
 447          * Check the security policy (SP) for the packet and, if
 448          * required, do IPsec-related processing.  There are two
 449          * cases here; the first time a packet is sent through
 450          * it will be untagged and handled by ipsec4_checkpolicy.
 451          * If the packet is resubmitted to ip_output (e.g. after
 452          * AH, ESP, etc. processing), there will be a tag to bypass
 453          * the lookup and related policy checking.
 454          */
 455         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 456         s = splnet();
 457         if (mtag != NULL) {
 458                 tdbi = (struct tdb_ident *)(mtag + 1);
 459                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 460                 if (sp == NULL)
 461                         *error = -EINVAL;       /* force silent drop */
 462                 m_tag_delete(*m, mtag);
 463         } else {
 464                 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 465                                         error, inp);
 466         }
 467         /*
 468          * There are four return cases:
 469          *    sp != NULL                    apply IPsec policy
 470          *    sp == NULL, error == 0        no IPsec handling needed
 471          *    sp == NULL, error == -EINVAL  discard packet w/o error
 472          *    sp == NULL, error != 0        discard packet, report error
 473          */
 474         if (sp != NULL) {
 475                 /* Loop detection, check if ipsec processing already done */
 476                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
 477                 for (mtag = m_tag_first(*m); mtag != NULL;
 478                      mtag = m_tag_next(*m, mtag)) {
 479                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 480                                 continue;
 481                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 482                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 483                                 continue;
 484                         /*
 485                          * Check if policy has an SA associated with it.
 486                          * This can happen when an SP has yet to acquire
 487                          * an SA; e.g. on first reference.  If it occurs,
 488                          * then we let ipsec4_process_packet do its thing.
 489                          */
 490                         if (sp->req->sav == NULL)
 491                                 break;
 492                         tdbi = (struct tdb_ident *)(mtag + 1);
 493                         if (tdbi->spi == sp->req->sav->spi &&
 494                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
 495                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
 496                                  sizeof (union sockaddr_union)) == 0) {
 497                                 /*
 498                                  * No IPsec processing is needed, free
 499                                  * reference to SP.
 500                                  *
 501                                  * NB: null pointer to avoid free at
 502                                  *     done: below.
 503                                  */
 504                                 KEY_FREESP(&sp), sp = NULL;
 505                                 splx(s);
 506                                 goto done;
 507                         }
 508                 }
 509
 510                 /*
 511                  * Do delayed checksums now because we send before
 512                  * this is done in the normal processing path.
 513                  */
 514                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 515                         in_delayed_cksum(*m);
 516                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 517                 }
 518
 519                 ip->ip_len = htons(ip->ip_len);
 520                 ip->ip_off = htons(ip->ip_off);
 521
 522                 /* NB: callee frees mbuf */
 523                 *error = ipsec4_process_packet(*m, sp->req, *flags, 0);
 524                 /*
 525                  * Preserve KAME behaviour: ENOENT can be returned
 526                  * when an SA acquire is in progress.  Don't propagate
 527                  * this to user-level; it confuses applications.
 528                  *
 529                  * XXX this will go away when the SADB is redone.
 530                  */
 531                 if (*error == ENOENT)
 532                         *error = 0;
 533                 splx(s);
 534                 goto reinjected;
 535         } else {        /* sp == NULL */
 536                 splx(s);
 537
 538                 if (*error != 0) {
 539                         /*
 540                          * Hack: -EINVAL is used to signal that a packet
 541                          * should be silently discarded.  This is typically
 542                          * because we asked key management for an SA and
 543                          * it was delayed (e.g. kicked up to IKE).
 544                          */
 545                         if (*error == -EINVAL)
 546                                 *error = 0;
 547                         goto bad;
 548                 } else {
 549                         /* No IPsec processing for this packet. */
 550                 }
 551 #ifdef notyet
 552                 /*
 553                  * If deferred crypto processing is needed, check that
 554                  * the interface supports it.
 555                  */
 556                 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED, NULL);
 557                 if (mtag != NULL && ((*ifp)->if_capenable & IFCAP_IPSEC) == 0) {
 558                         /* notify IPsec to do its own crypto */
 559                         ipsp_skipcrypto_unmark((struct tdb_ident *)(mtag + 1));
 560                         *error = EHOSTUNREACH;
 561                         goto bad;
 562                 }
 563 #endif
 564         }
 565 done:
 566         if (sp != NULL)
 567                 KEY_FREESP(&sp);
 568         return 0;
 569 reinjected:
 570         if (sp != NULL)
 571                 KEY_FREESP(&sp);
 572         return -1;
 573 bad:
 574         if (sp != NULL)
 575                 KEY_FREESP(&sp);
 576         return 1;
 577 #endif /* FAST_IPSEC */
 578         return 0;
 579 }
 580