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_VNET_INT(_net_inet6_ipsec6, OID_AUTO,
  94         filtertunnel, 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, struct secpolicy **sp)
 225 {
 226 #ifdef IPSEC
 227         struct tdb_ident *tdbi;
 228         struct m_tag *mtag;
 229         /* XXX int s; */
 230         if (sp == NULL)
 231                 return 1;
 232         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 233         if (mtag != NULL) {
 234                 tdbi = (struct tdb_ident *)(mtag + 1);
 235                 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 236                 if (*sp == NULL)
 237                         *error = -EINVAL;       /* force silent drop */
 238                 m_tag_delete(*m, mtag);
 239         } else {
 240                 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 241                                         error, inp);
 242         }
 243
 244         /*
 245          * There are four return cases:
 246          *    sp != NULL                    apply IPsec policy
 247          *    sp == NULL, error == 0        no IPsec handling needed
 248          *    sp == NULL, error == -EINVAL  discard packet w/o error
 249          *    sp == NULL, error != 0        discard packet, report error
 250          */
 251         if (*sp != NULL) {
 252                 /* Loop detection, check if ipsec processing already done */
 253                 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
 254                 for (mtag = m_tag_first(*m); mtag != NULL;
 255                      mtag = m_tag_next(*m, mtag)) {
 256                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 257                                 continue;
 258                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 259                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 260                                 continue;
 261                         /*
 262                          * Check if policy has no SA associated with it.
 263                          * This can happen when an SP has yet to acquire
 264                          * an SA; e.g. on first reference.  If it occurs,
 265                          * then we let ipsec4_process_packet do its thing.
 266                          */
 267                         if ((*sp)->req->sav == NULL)
 268                                 break;
 269                         tdbi = (struct tdb_ident *)(mtag + 1);
 270                         if (tdbi->spi == (*sp)->req->sav->spi &&
 271                             tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
 272                             bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
 273                                  sizeof (union sockaddr_union)) == 0) {
 274                                 /*
 275                                  * No IPsec processing is needed, free
 276                                  * reference to SP.
 277                                  *
 278                                  * NB: null pointer to avoid free at
 279                                  *     done: below.
 280                                  */
 281                                 KEY_FREESP(sp), *sp = NULL;
 282                                 goto done;
 283                         }
 284                 }
 285
 286                 /*
 287                  * Do delayed checksums now because we send before
 288                  * this is done in the normal processing path.
 289                  * For IPv6 we do delayed checksums in ip6_output.c.
 290                  */
 291 #ifdef INET
 292                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 293                         ipseclog((LOG_DEBUG,
 294                             "%s: we do not support IPv4 over IPv6", __func__));
 295                         in_delayed_cksum(*m);
 296                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 297                 }
 298 #endif
 299
 300                 /*
 301                  * Preserve KAME behaviour: ENOENT can be returned
 302                  * when an SA acquire is in progress.  Don't propagate
 303                  * this to user-level; it confuses applications.
 304                  *
 305                  * XXX this will go away when the SADB is redone.
 306                  */
 307                 if (*error == ENOENT)
 308                         *error = 0;
 309                 goto do_ipsec;
 310         } else {        /* sp == NULL */
 311                 if (*error != 0) {
 312                         /*
 313                          * Hack: -EINVAL is used to signal that a packet
 314                          * should be silently discarded.  This is typically
 315                          * because we asked key management for an SA and
 316                          * it was delayed (e.g. kicked up to IKE).
 317                          */
 318                         if (*error == -EINVAL)
 319                                 *error = 0;
 320                         goto bad;
 321                 } else {
 322                         /* No IPsec processing for this packet. */
 323                 }
 324         }
 325 done:
 326         return 0;
 327 do_ipsec:
 328         return -1;
 329 bad:
 330         return 1;
 331 #endif /* IPSEC */
 332         return 0;
 333 }
 334
 335 #if 0
 336 /*
 337  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 338  * Called from ip_forward().
 339  * Returns MTU suggestion for ICMP needfrag reply.
 340  */
 341 int
 342 ip6_ipsec_mtu(struct mbuf *m)
 343 {
 344         int mtu = 0;
 345         /*
 346          * If the packet is routed over IPsec tunnel, tell the
 347          * originator the tunnel MTU.
 348          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 349          * XXX quickhack!!!
 350          */
 351 #ifdef IPSEC
 352         struct secpolicy *sp = NULL;
 353         int ipsecerror;
 354         int ipsechdr;
 355         struct route *ro;
 356         sp = ipsec_getpolicybyaddr(m,
 357                                    IPSEC_DIR_OUTBOUND,
 358                                    IP_FORWARDING,
 359                                    &ipsecerror);
 360         if (sp != NULL) {
 361                 /* count IPsec header size */
 362                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
 363
 364                 /*
 365                  * find the correct route for outer IPv4
 366                  * header, compute tunnel MTU.
 367                  */
 368                 if (sp->req != NULL &&
 369                     sp->req->sav != NULL &&
 370                     sp->req->sav->sah != NULL) {
 371                         ro = &sp->req->sav->sah->route_cache.sa_route;
 372                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 373                                 mtu = ro->ro_rt->rt_mtu ? ro->ro_rt->rt_mtu :
 374                                     ro->ro_rt->rt_ifp->if_mtu;
 375                                 mtu -= ipsechdr;
 376                         }
 377                 }
 378                 KEY_FREESP(&sp);
 379         }
 380 #endif /* IPSEC */
 381         /* XXX else case missing. */
 382         return mtu;
 383 }
 384 #endif