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_ipsec.h"
  34
  35 #include <sys/param.h>
  36 #include <sys/systm.h>
  37 #include <sys/kernel.h>
  38 #include <sys/mac.h>
  39 #include <sys/malloc.h>
  40 #include <sys/mbuf.h>
  41 #include <sys/protosw.h>
  42 #include <sys/socket.h>
  43 #include <sys/socketvar.h>
  44 #include <sys/sysctl.h>
  45
  46 #include <net/if.h>
  47 #include <net/route.h>
  48
  49 #include <netinet/in.h>
  50 #include <netinet/in_systm.h>
  51 #include <netinet/in_var.h>
  52 #include <netinet/ip.h>
  53 #include <netinet/in_pcb.h>
  54 #include <netinet/ip_var.h>
  55 #include <netinet/ip_options.h>
  56
  57 #include <machine/in_cksum.h>
  58
  59 #ifdef IPSEC
  60 #include <netipsec/ipsec.h>
  61 #include <netipsec/ipsec6.h>
  62 #include <netipsec/xform.h>
  63 #include <netipsec/key.h>
  64 #ifdef IPSEC_DEBUG
  65 #include <netipsec/key_debug.h>
  66 #else
  67 #define KEYDEBUG(lev,arg)
  68 #endif
  69 #endif /*IPSEC*/
  70
  71 #include <netinet6/ip6_ipsec.h>
  72
  73 extern  struct protosw inet6sw[];
  74
  75 /*
  76  * Check if we have to jump over firewall processing for this packet.
  77  * Called from ip_input().
  78  * 1 = jump over firewall, 0 = packet goes through firewall.
  79  */
  80 int
  81 ip6_ipsec_filtertunnel(struct mbuf *m)
  82 {
  83 #if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL)
  84         /*
  85          * Bypass packet filtering for packets from a tunnel.
  86          */
  87         if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  88                 return 1;
  89 #endif
  90         return 0;
  91 }
  92
  93 /*
  94  * Check if this packet has an active SA and needs to be dropped instead
  95  * of forwarded.
  96  * Called from ip_input().
  97  * 1 = drop packet, 0 = forward packet.
  98  */
  99 int
 100 ip6_ipsec_fwd(struct mbuf *m)
 101 {
 102 #ifdef IPSEC
 103         struct m_tag *mtag;
 104         struct tdb_ident *tdbi;
 105         struct secpolicy *sp;
 106         int s, error;
 107         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 108         s = splnet();
 109         if (mtag != NULL) {
 110                 tdbi = (struct tdb_ident *)(mtag + 1);
 111                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 112         } else {
 113                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 114                                            IP_FORWARDING, &error);
 115         }
 116         if (sp == NULL) {       /* NB: can happen if error */
 117                 splx(s);
 118                 /*XXX error stat???*/
 119                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 120                 return 1;
 121         }
 122
 123         /*
 124          * Check security policy against packet attributes.
 125          */
 126         error = ipsec_in_reject(sp, m);
 127         KEY_FREESP(&sp);
 128         splx(s);
 129         if (error) {
 130                 ipstat.ips_cantforward++;
 131                 return 1;
 132         }
 133 #endif /* IPSEC */
 134         return 0;
 135 }
 136
 137 /*
 138  * Check if protocol type doesn't have a further header and do IPSEC
 139  * decryption or reject right now.  Protocols with further headers get
 140  * their IPSEC treatment within the protocol specific processing.
 141  * Called from ip_input().
 142  * 1 = drop packet, 0 = continue processing packet.
 143  */
 144 int
 145 ip6_ipsec_input(struct mbuf *m, int nxt)
 146 {
 147 #ifdef IPSEC
 148         struct m_tag *mtag;
 149         struct tdb_ident *tdbi;
 150         struct secpolicy *sp;
 151         int s, error;
 152         /*
 153          * enforce IPsec policy checking if we are seeing last header.
 154          * note that we do not visit this with protocols with pcb layer
 155          * code - like udp/tcp/raw ip.
 156          */
 157         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
 158             ipsec6_in_reject(m, NULL)) {
 159
 160                 /*
 161                  * Check if the packet has already had IPsec processing
 162                  * done.  If so, then just pass it along.  This tag gets
 163                  * set during AH, ESP, etc. input handling, before the
 164                  * packet is returned to the ip input queue for delivery.
 165                  */
 166                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 167                 s = splnet();
 168                 if (mtag != NULL) {
 169                         tdbi = (struct tdb_ident *)(mtag + 1);
 170                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 171                 } else {
 172                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 173                                                    IP_FORWARDING, &error);
 174                 }
 175                 if (sp != NULL) {
 176                         /*
 177                          * Check security policy against packet attributes.
 178                          */
 179                         error = ipsec_in_reject(sp, m);
 180                         KEY_FREESP(&sp);
 181                 } else {
 182                         /* XXX error stat??? */
 183                         error = EINVAL;
 184                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 185                         return 1;
 186                 }
 187                 splx(s);
 188                 if (error)
 189                         return 1;
 190         }
 191 #endif /* IPSEC */
 192         return 0;
 193 }
 194
 195 /*
 196  * Called from ip6_output().
 197  * 1 = drop packet, 0 = continue processing packet,
 198  * -1 = packet was reinjected and stop processing packet
 199  */
 200
 201 int
 202 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 203     struct ifnet **ifp, struct secpolicy **sp)
 204 {
 205 #ifdef IPSEC
 206         struct tdb_ident *tdbi;
 207         struct m_tag *mtag;
 208         /* XXX int s; */
 209         if (sp == NULL)
 210                 return 1;
 211         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 212         if (mtag != NULL) {
 213                 tdbi = (struct tdb_ident *)(mtag + 1);
 214                 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 215                 if (*sp == NULL)
 216                         *error = -EINVAL;       /* force silent drop */
 217                 m_tag_delete(*m, mtag);
 218         } else {
 219                 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 220                                         error, inp);
 221         }
 222
 223         /*
 224          * There are four return cases:
 225          *    sp != NULL                    apply IPsec policy
 226          *    sp == NULL, error == 0        no IPsec handling needed
 227          *    sp == NULL, error == -EINVAL  discard packet w/o error
 228          *    sp == NULL, error != 0        discard packet, report error
 229          */
 230         if (*sp != NULL) {
 231                 /* Loop detection, check if ipsec processing already done */
 232                 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
 233                 for (mtag = m_tag_first(*m); mtag != NULL;
 234                      mtag = m_tag_next(*m, mtag)) {
 235                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 236                                 continue;
 237                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 238                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 239                                 continue;
 240                         /*
 241                          * Check if policy has an SA associated with it.
 242                          * This can happen when an SP has yet to acquire
 243                          * an SA; e.g. on first reference.  If it occurs,
 244                          * then we let ipsec4_process_packet do its thing.
 245                          */
 246                         if ((*sp)->req->sav == NULL)
 247                                 break;
 248                         tdbi = (struct tdb_ident *)(mtag + 1);
 249                         if (tdbi->spi == (*sp)->req->sav->spi &&
 250                             tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
 251                             bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
 252                                  sizeof (union sockaddr_union)) == 0) {
 253                                 /*
 254                                  * No IPsec processing is needed, free
 255                                  * reference to SP.
 256                                  *
 257                                  * NB: null pointer to avoid free at
 258                                  *     done: below.
 259                                  */
 260                                 KEY_FREESP(sp), sp = NULL;
 261                                 /* XXX splx(s); */
 262                                 goto done;
 263                         }
 264                 }
 265
 266                 /*
 267                  * Do delayed checksums now because we send before
 268                  * this is done in the normal processing path.
 269                  */
 270                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 271                         in_delayed_cksum(*m);
 272                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 273                 }
 274
 275                 /*
 276                  * Preserve KAME behaviour: ENOENT can be returned
 277                  * when an SA acquire is in progress.  Don't propagate
 278                  * this to user-level; it confuses applications.
 279                  *
 280                  * XXX this will go away when the SADB is redone.
 281                  */
 282                 if (*error == ENOENT)
 283                         *error = 0;
 284                 goto do_ipsec;
 285         } else {        /* sp == NULL */
 286                 if (*error != 0) {
 287                         /*
 288                          * Hack: -EINVAL is used to signal that a packet
 289                          * should be silently discarded.  This is typically
 290                          * because we asked key management for an SA and
 291                          * it was delayed (e.g. kicked up to IKE).
 292                          */
 293                         if (*error == -EINVAL)
 294                                 *error = 0;
 295                         goto bad;
 296                 } else {
 297                         /* No IPsec processing for this packet. */
 298                 }
 299         }
 300 done:
 301         if (sp != NULL)
 302                 if (*sp != NULL)
 303                         KEY_FREESP(sp);
 304         return 0;
 305 do_ipsec:
 306         return -1;
 307 bad:
 308         if (sp != NULL)
 309                 if (*sp != NULL)
 310                         KEY_FREESP(sp);
 311         return 1;
 312 #endif /* IPSEC */
 313         return 0;
 314 }
 315
 316 /*
 317  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 318  * Called from ip_forward().
 319  * Returns MTU suggestion for ICMP needfrag reply.
 320  */
 321 int
 322 ip6_ipsec_mtu(struct mbuf *m)
 323 {
 324         int mtu = 0;
 325         /*
 326          * If the packet is routed over IPsec tunnel, tell the
 327          * originator the tunnel MTU.
 328          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 329          * XXX quickhack!!!
 330          */
 331         struct secpolicy *sp = NULL;
 332         int ipsecerror;
 333         int ipsechdr;
 334         struct route *ro;
 335 #ifdef IPSEC
 336         sp = ipsec_getpolicybyaddr(m,
 337                                    IPSEC_DIR_OUTBOUND,
 338                                    IP_FORWARDING,
 339                                    &ipsecerror);
 340 #endif /* IPSEC */
 341         if (sp != NULL) {
 342                 /* count IPsec header size */
 343                 ipsechdr = ipsec4_hdrsiz(m,
 344                                          IPSEC_DIR_OUTBOUND,
 345                                          NULL);
 346
 347                 /*
 348                  * find the correct route for outer IPv4
 349                  * header, compute tunnel MTU.
 350                  */
 351                 if (sp->req != NULL &&
 352                     sp->req->sav != NULL &&
 353                     sp->req->sav->sah != NULL) {
 354                         ro = &sp->req->sav->sah->sa_route;
 355                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 356                                 mtu =
 357                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 358                                     ro->ro_rt->rt_rmx.rmx_mtu :
 359                                     ro->ro_rt->rt_ifp->if_mtu;
 360                                 mtu -= ipsechdr;
 361                         }
 362                 }
 363 #ifdef IPSEC
 364                 KEY_FREESP(&sp);
 365 #endif /* IPSEC */
 366         }
 367         return mtu;
 368 }
 369