sys/netinet6/ip6_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
  30 #include <sys/cdefs.h>
  31 __FBSDID("$FreeBSD$");
  32
  33 #include "opt_inet.h"
  34 #include "opt_inet6.h"
  35 #include "opt_ipsec.h"
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/kernel.h>
  40 #include <sys/mac.h>
  41 #include <sys/malloc.h>
  42 #include <sys/mbuf.h>
  43 #include <sys/protosw.h>
  44 #include <sys/socket.h>
  45 #include <sys/socketvar.h>
  46 #include <sys/sysctl.h>
  47 #include <sys/syslog.h>
  48
  49 #include <net/if.h>
  50 #include <net/if_var.h>
  51 #include <net/route.h>
  52 #include <net/vnet.h>
  53
  54 #include <netinet/in.h>
  55 #include <netinet/in_systm.h>
  56 #include <netinet/in_var.h>
  57 #include <netinet/ip.h>
  58 #include <netinet/ip6.h>
  59 #include <netinet/in_pcb.h>
  60 #include <netinet/ip_var.h>
  61 #include <netinet/ip_options.h>
  62
  63 #include <machine/in_cksum.h>
  64
  65 #ifdef IPSEC
  66 #include <netipsec/ipsec.h>
  67 #include <netipsec/ipsec6.h>
  68 #include <netipsec/xform.h>
  69 #include <netipsec/key.h>
  70 #ifdef IPSEC_DEBUG
  71 #include <netipsec/key_debug.h>
  72 #else
  73 #define KEYDEBUG(lev,arg)
  74 #endif
  75 #endif /*IPSEC*/
  76
  77 #include <netinet6/ip6_ipsec.h>
  78 #include <netinet6/ip6_var.h>
  79
  80 extern  struct protosw inet6sw[];
  81
  82
  83 #ifdef INET6
  84 #ifdef IPSEC
  85 #ifdef IPSEC_FILTERTUNNEL
  86 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 1;
  87 #else
  88 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 0;
  89 #endif
  90 #define V_ip6_ipsec6_filtertunnel       VNET(ip6_ipsec6_filtertunnel)
  91
  92 SYSCTL_DECL(_net_inet6_ipsec6);
  93 SYSCTL_INT(_net_inet6_ipsec6, OID_AUTO, filtertunnel,
  94         CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_ipsec6_filtertunnel),  0,
  95         "If set filter packets from an IPsec tunnel.");
  96 #endif /* IPSEC */
  97 #endif /* INET6 */
  98
  99 /*
 100  * Check if we have to jump over firewall processing for this packet.
 101  * Called from ip6_input().
 102  * 1 = jump over firewall, 0 = packet goes through firewall.
 103  */
 104 int
 105 ip6_ipsec_filtertunnel(struct mbuf *m)
 106 {
 107 #ifdef IPSEC
 108
 109         /*
 110          * Bypass packet filtering for packets previously handled by IPsec.
 111          */
 112         if (!V_ip6_ipsec6_filtertunnel &&
 113             m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
 114                 return 1;
 115 #endif
 116         return 0;
 117 }
 118
 119 /*
 120  * Check if this packet has an active SA and needs to be dropped instead
 121  * of forwarded.
 122  * Called from ip6_input().
 123  * 1 = drop packet, 0 = forward packet.
 124  */
 125 int
 126 ip6_ipsec_fwd(struct mbuf *m)
 127 {
 128 #ifdef IPSEC
 129         struct m_tag *mtag;
 130         struct tdb_ident *tdbi;
 131         struct secpolicy *sp;
 132         int error;
 133         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 134         if (mtag != NULL) {
 135                 tdbi = (struct tdb_ident *)(mtag + 1);
 136                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 137         } else {
 138                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 139                                            IP_FORWARDING, &error);
 140         }
 141         if (sp == NULL) {       /* NB: can happen if error */
 142                 /*XXX error stat???*/
 143                 DPRINTF(("%s: no SP for forwarding\n", __func__));      /*XXX*/
 144                 return 1;
 145         }
 146
 147         /*
 148          * Check security policy against packet attributes.
 149          */
 150         error = ipsec_in_reject(sp, m);
 151         KEY_FREESP(&sp);
 152         if (error) {
 153                 IP6STAT_INC(ip6s_cantforward);
 154                 return 1;
 155         }
 156 #endif /* IPSEC */
 157         return 0;
 158 }
 159
 160 /*
 161  * Check if protocol type doesn't have a further header and do IPSEC
 162  * decryption or reject right now.  Protocols with further headers get
 163  * their IPSEC treatment within the protocol specific processing.
 164  * Called from ip6_input().
 165  * 1 = drop packet, 0 = continue processing packet.
 166  */
 167 int
 168 ip6_ipsec_input(struct mbuf *m, int nxt)
 169 {
 170 #ifdef IPSEC
 171         struct m_tag *mtag;
 172         struct tdb_ident *tdbi;
 173         struct secpolicy *sp;
 174         int error;
 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 ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
 181             ipsec6_in_reject(m, NULL)) {
 182
 183                 /*
 184                  * Check if the packet has already had IPsec processing
 185                  * done.  If so, then just pass it along.  This tag gets
 186                  * set during AH, ESP, etc. input handling, before the
 187                  * packet is returned to the ip input queue for delivery.
 188                  */
 189                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 190                 if (mtag != NULL) {
 191                         tdbi = (struct tdb_ident *)(mtag + 1);
 192                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 193                 } else {
 194                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 195                                                    IP_FORWARDING, &error);
 196                 }
 197                 if (sp != NULL) {
 198                         /*
 199                          * Check security policy against packet attributes.
 200                          */
 201                         error = ipsec_in_reject(sp, m);
 202                         KEY_FREESP(&sp);
 203                 } else {
 204                         /* XXX error stat??? */
 205                         error = EINVAL;
 206                         DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
 207                         return 1;
 208                 }
 209                 if (error)
 210                         return 1;
 211         }
 212 #endif /* IPSEC */
 213         return 0;
 214 }
 215
 216 /*
 217  * Called from ip6_output().
 218  * 1 = drop packet, 0 = continue processing packet,
 219  * -1 = packet was reinjected and stop processing packet
 220  */
 221
 222 int
 223 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 224     struct ifnet **ifp)
 225 {
 226 #ifdef IPSEC
 227         struct secpolicy *sp = NULL;
 228         struct tdb_ident *tdbi;
 229         struct m_tag *mtag;
 230         /* XXX int s; */
 231         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 232         if (mtag != NULL) {
 233                 tdbi = (struct tdb_ident *)(mtag + 1);
 234                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 235                 if (sp == NULL)
 236                         *error = -EINVAL;       /* force silent drop */
 237                 m_tag_delete(*m, mtag);
 238         } else {
 239                 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 240                                         error, inp);
 241         }
 242
 243         /*
 244          * There are four return cases:
 245          *    sp != NULL                    apply IPsec policy
 246          *    sp == NULL, error == 0        no IPsec handling needed
 247          *    sp == NULL, error == -EINVAL  discard packet w/o error
 248          *    sp == NULL, error != 0        discard packet, report error
 249          */
 250         if (sp != NULL) {
 251                 /* Loop detection, check if ipsec processing already done */
 252                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
 253                 for (mtag = m_tag_first(*m); mtag != NULL;
 254                      mtag = m_tag_next(*m, mtag)) {
 255                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 256                                 continue;
 257                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 258                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 259                                 continue;
 260                         /*
 261                          * Check if policy has no SA associated with it.
 262                          * This can happen when an SP has yet to acquire
 263                          * an SA; e.g. on first reference.  If it occurs,
 264                          * then we let ipsec4_process_packet do its thing.
 265                          */
 266                         if (sp->req->sav == NULL)
 267                                 break;
 268                         tdbi = (struct tdb_ident *)(mtag + 1);
 269                         if (tdbi->spi == sp->req->sav->spi &&
 270                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
 271                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
 272                                  sizeof (union sockaddr_union)) == 0) {
 273                                 /*
 274                                  * No IPsec processing is needed, free
 275                                  * reference to SP.
 276                                  *
 277                                  * NB: null pointer to avoid free at
 278                                  *     done: below.
 279                                  */
 280                                 KEY_FREESP(&sp), sp = NULL;
 281                                 goto done;
 282                         }
 283                 }
 284
 285                 /*
 286                  * Do delayed checksums now because we send before
 287                  * this is done in the normal processing path.
 288                  */
 289 #ifdef INET
 290                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 291                         in_delayed_cksum(*m);
 292                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 293                 }
 294 #endif
 295                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
 296                         in6_delayed_cksum(*m, (*m)->m_pkthdr.len - sizeof(struct ip6_hdr),
 297                                                         sizeof(struct ip6_hdr));
 298                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
 299                 }
 300 #ifdef SCTP
 301                 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
 302                         sctp_delayed_cksum(*m, sizeof(struct ip6_hdr));
 303                         (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
 304                 }
 305 #endif
 306
 307                 /* NB: callee frees mbuf */
 308                 *error = ipsec6_process_packet(*m, sp->req);
 309
 310                 if (*error == EJUSTRETURN) {
 311                         /*
 312                          * We had a SP with a level of 'use' and no SA. We
 313                          * will just continue to process the packet without
 314                          * IPsec processing.
 315                          */
 316                         *error = 0;
 317                         goto done;
 318                 }
 319
 320                 /*
 321                  * Preserve KAME behaviour: ENOENT can be returned
 322                  * when an SA acquire is in progress.  Don't propagate
 323                  * this to user-level; it confuses applications.
 324                  *
 325                  * XXX this will go away when the SADB is redone.
 326                  */
 327                 if (*error == ENOENT)
 328                         *error = 0;
 329                 goto reinjected;
 330         } else {        /* sp == NULL */
 331                 if (*error != 0) {
 332                         /*
 333                          * Hack: -EINVAL is used to signal that a packet
 334                          * should be silently discarded.  This is typically
 335                          * because we asked key management for an SA and
 336                          * it was delayed (e.g. kicked up to IKE).
 337                          */
 338                         if (*error == -EINVAL)
 339                                 *error = 0;
 340                         goto bad;
 341                 } else {
 342                         /* No IPsec processing for this packet. */
 343                 }
 344         }
 345 done:
 346         if (sp != NULL)
 347                 KEY_FREESP(&sp);
 348         return 0;
 349 reinjected:
 350         if (sp != NULL)
 351                 KEY_FREESP(&sp);
 352         return -1;
 353 bad:
 354         if (sp != NULL)
 355                 KEY_FREESP(&sp);
 356         return 1;
 357 #endif /* IPSEC */
 358         return 0;
 359 }
 360
 361 #if 0
 362 /*
 363  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 364  * Called from ip_forward().
 365  * Returns MTU suggestion for ICMP needfrag reply.
 366  */
 367 int
 368 ip6_ipsec_mtu(struct mbuf *m)
 369 {
 370         int mtu = 0;
 371         /*
 372          * If the packet is routed over IPsec tunnel, tell the
 373          * originator the tunnel MTU.
 374          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 375          * XXX quickhack!!!
 376          */
 377 #ifdef IPSEC
 378         struct secpolicy *sp = NULL;
 379         int ipsecerror;
 380         int ipsechdr;
 381         struct route *ro;
 382         sp = ipsec_getpolicybyaddr(m,
 383                                    IPSEC_DIR_OUTBOUND,
 384                                    IP_FORWARDING,
 385                                    &ipsecerror);
 386         if (sp != NULL) {
 387                 /* count IPsec header size */
 388                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
 389
 390                 /*
 391                  * find the correct route for outer IPv4
 392                  * header, compute tunnel MTU.
 393                  */
 394                 if (sp->req != NULL &&
 395                     sp->req->sav != NULL &&
 396                     sp->req->sav->sah != NULL) {
 397                         ro = &sp->req->sav->sah->route_cache.sa_route;
 398                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 399                                 mtu = ro->ro_rt->rt_mtu ? ro->ro_rt->rt_mtu :
 400                                     ro->ro_rt->rt_ifp->if_mtu;
 401                                 mtu -= ipsechdr;
 402                         }
 403                 }
 404                 KEY_FREESP(&sp);
 405         }
 406 #endif /* IPSEC */
 407         /* XXX else case missing. */
 408         return mtu;
 409 }
 410 #endif