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/vnet.h>
  51
  52 #include <netinet/in.h>
  53 #include <netinet/in_systm.h>
  54 #include <netinet/in_var.h>
  55 #include <netinet/ip.h>
  56 #include <netinet/ip6.h>
  57 #include <netinet/in_pcb.h>
  58 #include <netinet/ip_var.h>
  59 #include <netinet/ip_options.h>
  60
  61 #include <machine/in_cksum.h>
  62
  63 #ifdef IPSEC
  64 #include <netipsec/ipsec.h>
  65 #include <netipsec/ipsec6.h>
  66 #include <netipsec/xform.h>
  67 #include <netipsec/key.h>
  68 #ifdef IPSEC_DEBUG
  69 #include <netipsec/key_debug.h>
  70 #else
  71 #define KEYDEBUG(lev,arg)
  72 #endif
  73 #endif /*IPSEC*/
  74
  75 #include <netinet6/ip6_ipsec.h>
  76 #include <netinet6/ip6_var.h>
  77
  78 extern  struct protosw inet6sw[];
  79
  80
  81 #ifdef INET6
  82 #ifdef IPSEC
  83 #ifdef IPSEC_FILTERTUNNEL
  84 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 1;
  85 #else
  86 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 0;
  87 #endif
  88 #define V_ip6_ipsec6_filtertunnel       VNET(ip6_ipsec6_filtertunnel)
  89
  90 SYSCTL_DECL(_net_inet6_ipsec6);
  91 SYSCTL_VNET_INT(_net_inet6_ipsec6, OID_AUTO,
  92         filtertunnel, CTLFLAG_RW, &VNET_NAME(ip6_ipsec6_filtertunnel),  0,
  93         "If set filter packets from an IPsec tunnel.");
  94 #endif /* IPSEC */
  95 #endif /* INET6 */
  96
  97 /*
  98  * Check if we have to jump over firewall processing for this packet.
  99  * Called from ip6_input().
 100  * 1 = jump over firewall, 0 = packet goes through firewall.
 101  */
 102 int
 103 ip6_ipsec_filtertunnel(struct mbuf *m)
 104 {
 105 #ifdef IPSEC
 106
 107         /*
 108          * Bypass packet filtering for packets previously handled by IPsec.
 109          */
 110         if (!V_ip6_ipsec6_filtertunnel &&
 111             m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
 112                 return 1;
 113 #endif
 114         return 0;
 115 }
 116
 117 /*
 118  * Check if this packet has an active SA and needs to be dropped instead
 119  * of forwarded.
 120  * Called from ip6_input().
 121  * 1 = drop packet, 0 = forward packet.
 122  */
 123 int
 124 ip6_ipsec_fwd(struct mbuf *m)
 125 {
 126 #ifdef IPSEC
 127         struct m_tag *mtag;
 128         struct tdb_ident *tdbi;
 129         struct secpolicy *sp;
 130         int error;
 131         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 132         if (mtag != NULL) {
 133                 tdbi = (struct tdb_ident *)(mtag + 1);
 134                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 135         } else {
 136                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 137                                            IP_FORWARDING, &error);
 138         }
 139         if (sp == NULL) {       /* NB: can happen if error */
 140                 /*XXX error stat???*/
 141                 DPRINTF(("%s: no SP for forwarding\n", __func__));      /*XXX*/
 142                 return 1;
 143         }
 144
 145         /*
 146          * Check security policy against packet attributes.
 147          */
 148         error = ipsec_in_reject(sp, m);
 149         KEY_FREESP(&sp);
 150         if (error) {
 151                 IP6STAT_INC(ip6s_cantforward);
 152                 return 1;
 153         }
 154 #endif /* IPSEC */
 155         return 0;
 156 }
 157
 158 /*
 159  * Check if protocol type doesn't have a further header and do IPSEC
 160  * decryption or reject right now.  Protocols with further headers get
 161  * their IPSEC treatment within the protocol specific processing.
 162  * Called from ip6_input().
 163  * 1 = drop packet, 0 = continue processing packet.
 164  */
 165 int
 166 ip6_ipsec_input(struct mbuf *m, int nxt)
 167 {
 168 #ifdef IPSEC
 169         struct m_tag *mtag;
 170         struct tdb_ident *tdbi;
 171         struct secpolicy *sp;
 172         int error;
 173         /*
 174          * enforce IPsec policy checking if we are seeing last header.
 175          * note that we do not visit this with protocols with pcb layer
 176          * code - like udp/tcp/raw ip.
 177          */
 178         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
 179             ipsec6_in_reject(m, NULL)) {
 180
 181                 /*
 182                  * Check if the packet has already had IPsec processing
 183                  * done.  If so, then just pass it along.  This tag gets
 184                  * set during AH, ESP, etc. input handling, before the
 185                  * packet is returned to the ip input queue for delivery.
 186                  */
 187                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 188                 if (mtag != NULL) {
 189                         tdbi = (struct tdb_ident *)(mtag + 1);
 190                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 191                 } else {
 192                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 193                                                    IP_FORWARDING, &error);
 194                 }
 195                 if (sp != NULL) {
 196                         /*
 197                          * Check security policy against packet attributes.
 198                          */
 199                         error = ipsec_in_reject(sp, m);
 200                         KEY_FREESP(&sp);
 201                 } else {
 202                         /* XXX error stat??? */
 203                         error = EINVAL;
 204                         DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
 205                         return 1;
 206                 }
 207                 if (error)
 208                         return 1;
 209         }
 210 #endif /* IPSEC */
 211         return 0;
 212 }
 213
 214 /*
 215  * Called from ip6_output().
 216  * 1 = drop packet, 0 = continue processing packet,
 217  * -1 = packet was reinjected and stop processing packet
 218  */
 219
 220 int
 221 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 222     struct ifnet **ifp)
 223 {
 224 #ifdef IPSEC
 225         struct secpolicy *sp = NULL;
 226         struct tdb_ident *tdbi;
 227         struct m_tag *mtag;
 228         /* XXX int s; */
 229         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 230         if (mtag != NULL) {
 231                 tdbi = (struct tdb_ident *)(mtag + 1);
 232                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 233                 if (sp == NULL)
 234                         *error = -EINVAL;       /* force silent drop */
 235                 m_tag_delete(*m, mtag);
 236         } else {
 237                 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 238                                         error, inp);
 239         }
 240
 241         /*
 242          * There are four return cases:
 243          *    sp != NULL                    apply IPsec policy
 244          *    sp == NULL, error == 0        no IPsec handling needed
 245          *    sp == NULL, error == -EINVAL  discard packet w/o error
 246          *    sp == NULL, error != 0        discard packet, report error
 247          */
 248         if (sp != NULL) {
 249                 /* Loop detection, check if ipsec processing already done */
 250                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
 251                 for (mtag = m_tag_first(*m); mtag != NULL;
 252                      mtag = m_tag_next(*m, mtag)) {
 253                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 254                                 continue;
 255                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 256                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 257                                 continue;
 258                         /*
 259                          * Check if policy has no SA associated with it.
 260                          * This can happen when an SP has yet to acquire
 261                          * an SA; e.g. on first reference.  If it occurs,
 262                          * then we let ipsec4_process_packet do its thing.
 263                          */
 264                         if (sp->req->sav == NULL)
 265                                 break;
 266                         tdbi = (struct tdb_ident *)(mtag + 1);
 267                         if (tdbi->spi == sp->req->sav->spi &&
 268                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
 269                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
 270                                  sizeof (union sockaddr_union)) == 0) {
 271                                 /*
 272                                  * No IPsec processing is needed, free
 273                                  * reference to SP.
 274                                  */
 275                                 goto done;
 276                         }
 277                 }
 278
 279                 /*
 280                  * Do delayed checksums now because we send before
 281                  * this is done in the normal processing path.
 282                  */
 283 #ifdef INET
 284                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 285                         in_delayed_cksum(*m);
 286                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 287                 }
 288 #endif
 289                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
 290                         in6_delayed_cksum(*m, (*m)->m_pkthdr.len - sizeof(struct ip6_hdr),
 291                                                         sizeof(struct ip6_hdr));
 292                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
 293                 }
 294 #ifdef SCTP
 295                 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
 296                         sctp_delayed_cksum(*m, sizeof(struct ip6_hdr));
 297                         (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
 298                 }
 299 #endif
 300
 301                 /* NB: callee frees mbuf */
 302                 *error = ipsec6_process_packet(*m, sp->req);
 303
 304                 if (*error == EJUSTRETURN) {
 305                         /*
 306                          * We had a SP with a level of 'use' and no SA. We
 307                          * will just continue to process the packet without
 308                          * IPsec processing.
 309                          */
 310                         *error = 0;
 311                         goto done;
 312                 }
 313
 314                 /*
 315                  * Preserve KAME behaviour: ENOENT can be returned
 316                  * when an SA acquire is in progress.  Don't propagate
 317                  * this to user-level; it confuses applications.
 318                  *
 319                  * XXX this will go away when the SADB is redone.
 320                  */
 321                 if (*error == ENOENT)
 322                         *error = 0;
 323                 goto reinjected;
 324         } else {        /* sp == NULL */
 325                 if (*error != 0) {
 326                         /*
 327                          * Hack: -EINVAL is used to signal that a packet
 328                          * should be silently discarded.  This is typically
 329                          * because we asked key management for an SA and
 330                          * it was delayed (e.g. kicked up to IKE).
 331                          */
 332                         if (*error == -EINVAL)
 333                                 *error = 0;
 334                         goto bad;
 335                 } else {
 336                         /* No IPsec processing for this packet. */
 337                 }
 338         }
 339 done:
 340         if (sp != NULL)
 341                 KEY_FREESP(&sp);
 342         return 0;
 343 reinjected:
 344         if (sp != NULL)
 345                 KEY_FREESP(&sp);
 346         return -1;
 347 bad:
 348         if (sp != NULL)
 349                 KEY_FREESP(&sp);
 350         return 1;
 351 #endif /* IPSEC */
 352         return 0;
 353 }
 354
 355 #if 0
 356 /*
 357  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 358  * Called from ip_forward().
 359  * Returns MTU suggestion for ICMP needfrag reply.
 360  */
 361 int
 362 ip6_ipsec_mtu(struct mbuf *m)
 363 {
 364         int mtu = 0;
 365         /*
 366          * If the packet is routed over IPsec tunnel, tell the
 367          * originator the tunnel MTU.
 368          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 369          * XXX quickhack!!!
 370          */
 371 #ifdef IPSEC
 372         struct secpolicy *sp = NULL;
 373         int ipsecerror;
 374         int ipsechdr;
 375         struct route *ro;
 376         sp = ipsec_getpolicybyaddr(m,
 377                                    IPSEC_DIR_OUTBOUND,
 378                                    IP_FORWARDING,
 379                                    &ipsecerror);
 380         if (sp != NULL) {
 381                 /* count IPsec header size */
 382                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
 383
 384                 /*
 385                  * find the correct route for outer IPv4
 386                  * header, compute tunnel MTU.
 387                  */
 388                 if (sp->req != NULL &&
 389                     sp->req->sav != NULL &&
 390                     sp->req->sav->sah != NULL) {
 391                         ro = &sp->req->sav->sah->route_cache.sa_route;
 392                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 393                                 mtu = ro->ro_rt->rt_mtu ? ro->ro_rt->rt_mtu :
 394                                     ro->ro_rt->rt_ifp->if_mtu;
 395                                 mtu -= ipsechdr;
 396                         }
 397                 }
 398                 KEY_FREESP(&sp);
 399         }
 400 #endif /* IPSEC */
 401         /* XXX else case missing. */
 402         return mtu;
 403 }
 404 #endif