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 #if defined(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 s, error;
 132         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 133         s = splnet();
 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                 splx(s);
 143                 /*XXX error stat???*/
 144                 DPRINTF(("%s: no SP for forwarding\n", __func__));      /*XXX*/
 145                 return 1;
 146         }
 147
 148         /*
 149          * Check security policy against packet attributes.
 150          */
 151         error = ipsec_in_reject(sp, m);
 152         KEY_FREESP(&sp);
 153         splx(s);
 154         if (error) {
 155                 V_ip6stat.ip6s_cantforward++;
 156                 return 1;
 157         }
 158 #endif /* IPSEC */
 159         return 0;
 160 }
 161
 162 /*
 163  * Check if protocol type doesn't have a further header and do IPSEC
 164  * decryption or reject right now.  Protocols with further headers get
 165  * their IPSEC treatment within the protocol specific processing.
 166  * Called from ip6_input().
 167  * 1 = drop packet, 0 = continue processing packet.
 168  */
 169 int
 170 ip6_ipsec_input(struct mbuf *m, int nxt)
 171 {
 172 #ifdef IPSEC
 173         struct m_tag *mtag;
 174         struct tdb_ident *tdbi;
 175         struct secpolicy *sp;
 176         int s, error;
 177         /*
 178          * enforce IPsec policy checking if we are seeing last header.
 179          * note that we do not visit this with protocols with pcb layer
 180          * code - like udp/tcp/raw ip.
 181          */
 182         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
 183             ipsec6_in_reject(m, NULL)) {
 184
 185                 /*
 186                  * Check if the packet has already had IPsec processing
 187                  * done.  If so, then just pass it along.  This tag gets
 188                  * set during AH, ESP, etc. input handling, before the
 189                  * packet is returned to the ip input queue for delivery.
 190                  */
 191                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 192                 s = splnet();
 193                 if (mtag != NULL) {
 194                         tdbi = (struct tdb_ident *)(mtag + 1);
 195                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 196                 } else {
 197                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 198                                                    IP_FORWARDING, &error);
 199                 }
 200                 if (sp != NULL) {
 201                         /*
 202                          * Check security policy against packet attributes.
 203                          */
 204                         error = ipsec_in_reject(sp, m);
 205                         KEY_FREESP(&sp);
 206                 } else {
 207                         /* XXX error stat??? */
 208                         error = EINVAL;
 209                         DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
 210                         return 1;
 211                 }
 212                 splx(s);
 213                 if (error)
 214                         return 1;
 215         }
 216 #endif /* IPSEC */
 217         return 0;
 218 }
 219
 220 /*
 221  * Called from ip6_output().
 222  * 1 = drop packet, 0 = continue processing packet,
 223  * -1 = packet was reinjected and stop processing packet
 224  */
 225
 226 int
 227 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 228     struct ifnet **ifp, struct secpolicy **sp)
 229 {
 230 #ifdef IPSEC
 231         struct tdb_ident *tdbi;
 232         struct m_tag *mtag;
 233         /* XXX int s; */
 234         if (sp == NULL)
 235                 return 1;
 236         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 237         if (mtag != NULL) {
 238                 tdbi = (struct tdb_ident *)(mtag + 1);
 239                 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 240                 if (*sp == NULL)
 241                         *error = -EINVAL;       /* force silent drop */
 242                 m_tag_delete(*m, mtag);
 243         } else {
 244                 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 245                                         error, inp);
 246         }
 247
 248         /*
 249          * There are four return cases:
 250          *    sp != NULL                    apply IPsec policy
 251          *    sp == NULL, error == 0        no IPsec handling needed
 252          *    sp == NULL, error == -EINVAL  discard packet w/o error
 253          *    sp == NULL, error != 0        discard packet, report error
 254          */
 255         if (*sp != NULL) {
 256                 /* Loop detection, check if ipsec processing already done */
 257                 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
 258                 for (mtag = m_tag_first(*m); mtag != NULL;
 259                      mtag = m_tag_next(*m, mtag)) {
 260                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 261                                 continue;
 262                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 263                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 264                                 continue;
 265                         /*
 266                          * Check if policy has no SA associated with it.
 267                          * This can happen when an SP has yet to acquire
 268                          * an SA; e.g. on first reference.  If it occurs,
 269                          * then we let ipsec4_process_packet do its thing.
 270                          */
 271                         if ((*sp)->req->sav == NULL)
 272                                 break;
 273                         tdbi = (struct tdb_ident *)(mtag + 1);
 274                         if (tdbi->spi == (*sp)->req->sav->spi &&
 275                             tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
 276                             bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
 277                                  sizeof (union sockaddr_union)) == 0) {
 278                                 /*
 279                                  * No IPsec processing is needed, free
 280                                  * reference to SP.
 281                                  *
 282                                  * NB: null pointer to avoid free at
 283                                  *     done: below.
 284                                  */
 285                                 KEY_FREESP(sp), *sp = NULL;
 286                                 /* XXX splx(s); */
 287                                 goto done;
 288                         }
 289                 }
 290
 291                 /*
 292                  * Do delayed checksums now because we send before
 293                  * this is done in the normal processing path.
 294                  * For IPv6 we do delayed checksums in ip6_output.c.
 295                  */
 296 #ifdef INET
 297                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 298                         ipseclog((LOG_DEBUG,
 299                             "%s: we do not support IPv4 over IPv6", __func__));
 300                         in_delayed_cksum(*m);
 301                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 302                 }
 303 #endif
 304
 305                 /*
 306                  * Preserve KAME behaviour: ENOENT can be returned
 307                  * when an SA acquire is in progress.  Don't propagate
 308                  * this to user-level; it confuses applications.
 309                  *
 310                  * XXX this will go away when the SADB is redone.
 311                  */
 312                 if (*error == ENOENT)
 313                         *error = 0;
 314                 goto do_ipsec;
 315         } else {        /* sp == NULL */
 316                 if (*error != 0) {
 317                         /*
 318                          * Hack: -EINVAL is used to signal that a packet
 319                          * should be silently discarded.  This is typically
 320                          * because we asked key management for an SA and
 321                          * it was delayed (e.g. kicked up to IKE).
 322                          */
 323                         if (*error == -EINVAL)
 324                                 *error = 0;
 325                         goto bad;
 326                 } else {
 327                         /* No IPsec processing for this packet. */
 328                 }
 329         }
 330 done:
 331         return 0;
 332 do_ipsec:
 333         return -1;
 334 bad:
 335         return 1;
 336 #endif /* IPSEC */
 337         return 0;
 338 }
 339
 340 #if 0
 341 /*
 342  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 343  * Called from ip_forward().
 344  * Returns MTU suggestion for ICMP needfrag reply.
 345  */
 346 int
 347 ip6_ipsec_mtu(struct mbuf *m)
 348 {
 349         int mtu = 0;
 350         /*
 351          * If the packet is routed over IPsec tunnel, tell the
 352          * originator the tunnel MTU.
 353          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 354          * XXX quickhack!!!
 355          */
 356 #ifdef IPSEC
 357         struct secpolicy *sp = NULL;
 358         int ipsecerror;
 359         int ipsechdr;
 360         struct route *ro;
 361         sp = ipsec_getpolicybyaddr(m,
 362                                    IPSEC_DIR_OUTBOUND,
 363                                    IP_FORWARDING,
 364                                    &ipsecerror);
 365         if (sp != NULL) {
 366                 /* count IPsec header size */
 367                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
 368
 369                 /*
 370                  * find the correct route for outer IPv4
 371                  * header, compute tunnel MTU.
 372                  */
 373                 if (sp->req != NULL &&
 374                     sp->req->sav != NULL &&
 375                     sp->req->sav->sah != NULL) {
 376                         ro = &sp->req->sav->sah->route_cache.sa_route;
 377                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 378                                 mtu =
 379                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 380                                     ro->ro_rt->rt_rmx.rmx_mtu :
 381                                     ro->ro_rt->rt_ifp->if_mtu;
 382                                 mtu -= ipsechdr;
 383                         }
 384                 }
 385                 KEY_FREESP(&sp);
 386         }
 387 #endif /* IPSEC */
 388         /* XXX else case missing. */
 389         return mtu;
 390 }
 391 #endif