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/route.h>
  51 #include <net/vnet.h>
  52
  53 #include <netinet/in.h>
  54 #include <netinet/in_systm.h>
  55 #include <netinet/in_var.h>
  56 #include <netinet/ip.h>
  57 #include <netinet/ip6.h>
  58 #include <netinet/in_pcb.h>
  59 #include <netinet/ip_var.h>
  60 #include <netinet/ip_options.h>
  61
  62 #include <machine/in_cksum.h>
  63
  64 #ifdef IPSEC
  65 #include <netipsec/ipsec.h>
  66 #include <netipsec/ipsec6.h>
  67 #include <netipsec/xform.h>
  68 #include <netipsec/key.h>
  69 #ifdef IPSEC_DEBUG
  70 #include <netipsec/key_debug.h>
  71 #else
  72 #define KEYDEBUG(lev,arg)
  73 #endif
  74 #endif /*IPSEC*/
  75
  76 #include <netinet6/ip6_ipsec.h>
  77 #include <netinet6/ip6_var.h>
  78
  79 extern  struct protosw inet6sw[];
  80
  81
  82 #ifdef INET6
  83 #ifdef IPSEC
  84 #ifdef IPSEC_FILTERTUNNEL
  85 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 1;
  86 #else
  87 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 0;
  88 #endif
  89 #define V_ip6_ipsec6_filtertunnel       VNET(ip6_ipsec6_filtertunnel)
  90
  91 SYSCTL_DECL(_net_inet6_ipsec6);
  92 SYSCTL_VNET_INT(_net_inet6_ipsec6, OID_AUTO,
  93         filtertunnel, CTLFLAG_RW, &VNET_NAME(ip6_ipsec6_filtertunnel),  0,
  94         "If set filter packets from an IPsec tunnel.");
  95 #endif /* IPSEC */
  96 #endif /* INET6 */
  97
  98 /*
  99  * Check if we have to jump over firewall processing for this packet.
 100  * Called from ip6_input().
 101  * 1 = jump over firewall, 0 = packet goes through firewall.
 102  */
 103 int
 104 ip6_ipsec_filtertunnel(struct mbuf *m)
 105 {
 106 #ifdef IPSEC
 107
 108         /*
 109          * Bypass packet filtering for packets previously handled by IPsec.
 110          */
 111         if (!V_ip6_ipsec6_filtertunnel &&
 112             m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
 113                 return 1;
 114 #endif
 115         return 0;
 116 }
 117
 118 /*
 119  * Check if this packet has an active SA and needs to be dropped instead
 120  * of forwarded.
 121  * Called from ip6_input().
 122  * 1 = drop packet, 0 = forward packet.
 123  */
 124 int
 125 ip6_ipsec_fwd(struct mbuf *m)
 126 {
 127 #ifdef IPSEC
 128         struct m_tag *mtag;
 129         struct tdb_ident *tdbi;
 130         struct secpolicy *sp;
 131         int error;
 132         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 133         if (mtag != NULL) {
 134                 tdbi = (struct tdb_ident *)(mtag + 1);
 135                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 136         } else {
 137                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 138                                            IP_FORWARDING, &error);
 139         }
 140         if (sp == NULL) {       /* NB: can happen if error */
 141                 /*XXX error stat???*/
 142                 DPRINTF(("%s: no SP for forwarding\n", __func__));      /*XXX*/
 143                 return 1;
 144         }
 145
 146         /*
 147          * Check security policy against packet attributes.
 148          */
 149         error = ipsec_in_reject(sp, m);
 150         KEY_FREESP(&sp);
 151         if (error) {
 152                 IP6STAT_INC(ip6s_cantforward);
 153                 return 1;
 154         }
 155 #endif /* IPSEC */
 156         return 0;
 157 }
 158
 159 /*
 160  * Check if protocol type doesn't have a further header and do IPSEC
 161  * decryption or reject right now.  Protocols with further headers get
 162  * their IPSEC treatment within the protocol specific processing.
 163  * Called from ip6_input().
 164  * 1 = drop packet, 0 = continue processing packet.
 165  */
 166 int
 167 ip6_ipsec_input(struct mbuf *m, int nxt)
 168 {
 169 #ifdef IPSEC
 170         struct m_tag *mtag;
 171         struct tdb_ident *tdbi;
 172         struct secpolicy *sp;
 173         int error;
 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 ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
 180             ipsec6_in_reject(m, NULL)) {
 181
 182                 /*
 183                  * Check if the packet has already had IPsec processing
 184                  * done.  If so, then just pass it along.  This tag gets
 185                  * set during AH, ESP, etc. input handling, before the
 186                  * packet is returned to the ip input queue for delivery.
 187                  */
 188                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 189                 if (mtag != NULL) {
 190                         tdbi = (struct tdb_ident *)(mtag + 1);
 191                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 192                 } else {
 193                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 194                                                    IP_FORWARDING, &error);
 195                 }
 196                 if (sp != NULL) {
 197                         /*
 198                          * Check security policy against packet attributes.
 199                          */
 200                         error = ipsec_in_reject(sp, m);
 201                         KEY_FREESP(&sp);
 202                 } else {
 203                         /* XXX error stat??? */
 204                         error = EINVAL;
 205                         DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
 206                         return 1;
 207                 }
 208                 if (error)
 209                         return 1;
 210         }
 211 #endif /* IPSEC */
 212         return 0;
 213 }
 214
 215 /*
 216  * Called from ip6_output().
 217  * 1 = drop packet, 0 = continue processing packet,
 218  * -1 = packet was reinjected and stop processing packet
 219  */
 220
 221 int
 222 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 223     struct ifnet **ifp, struct secpolicy **sp)
 224 {
 225 #ifdef IPSEC
 226         struct tdb_ident *tdbi;
 227         struct m_tag *mtag;
 228         /* XXX int s; */
 229         if (sp == NULL)
 230                 return 1;
 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                  * For IPv6 we do delayed checksums in ip6_output.c.
 289                  */
 290 #ifdef INET
 291                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 292                         ipseclog((LOG_DEBUG,
 293                             "%s: we do not support IPv4 over IPv6", __func__));
 294                         in_delayed_cksum(*m);
 295                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 296                 }
 297 #endif
 298
 299                 /*
 300                  * Preserve KAME behaviour: ENOENT can be returned
 301                  * when an SA acquire is in progress.  Don't propagate
 302                  * this to user-level; it confuses applications.
 303                  *
 304                  * XXX this will go away when the SADB is redone.
 305                  */
 306                 if (*error == ENOENT)
 307                         *error = 0;
 308                 goto do_ipsec;
 309         } else {        /* sp == NULL */
 310                 if (*error != 0) {
 311                         /*
 312                          * Hack: -EINVAL is used to signal that a packet
 313                          * should be silently discarded.  This is typically
 314                          * because we asked key management for an SA and
 315                          * it was delayed (e.g. kicked up to IKE).
 316                          */
 317                         if (*error == -EINVAL)
 318                                 *error = 0;
 319                         goto bad;
 320                 } else {
 321                         /* No IPsec processing for this packet. */
 322                 }
 323         }
 324 done:
 325         return 0;
 326 do_ipsec:
 327         return -1;
 328 bad:
 329         return 1;
 330 #endif /* IPSEC */
 331         return 0;
 332 }
 333
 334 #if 0
 335 /*
 336  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 337  * Called from ip_forward().
 338  * Returns MTU suggestion for ICMP needfrag reply.
 339  */
 340 int
 341 ip6_ipsec_mtu(struct mbuf *m)
 342 {
 343         int mtu = 0;
 344         /*
 345          * If the packet is routed over IPsec tunnel, tell the
 346          * originator the tunnel MTU.
 347          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 348          * XXX quickhack!!!
 349          */
 350 #ifdef IPSEC
 351         struct secpolicy *sp = NULL;
 352         int ipsecerror;
 353         int ipsechdr;
 354         struct route *ro;
 355         sp = ipsec_getpolicybyaddr(m,
 356                                    IPSEC_DIR_OUTBOUND,
 357                                    IP_FORWARDING,
 358                                    &ipsecerror);
 359         if (sp != NULL) {
 360                 /* count IPsec header size */
 361                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
 362
 363                 /*
 364                  * find the correct route for outer IPv4
 365                  * header, compute tunnel MTU.
 366                  */
 367                 if (sp->req != NULL &&
 368                     sp->req->sav != NULL &&
 369                     sp->req->sav->sah != NULL) {
 370                         ro = &sp->req->sav->sah->route_cache.sa_route;
 371                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 372                                 mtu =
 373                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 374                                     ro->ro_rt->rt_rmx.rmx_mtu :
 375                                     ro->ro_rt->rt_ifp->if_mtu;
 376                                 mtu -= ipsechdr;
 377                         }
 378                 }
 379                 KEY_FREESP(&sp);
 380         }
 381 #endif /* IPSEC */
 382         /* XXX else case missing. */
 383         return mtu;
 384 }
 385 #endif