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  * $FreeBSD$
  30  */
  31
  32 #include "opt_ipsec.h"
  33
  34 #include <sys/param.h>
  35 #include <sys/systm.h>
  36 #include <sys/kernel.h>
  37 #include <sys/mac.h>
  38 #include <sys/malloc.h>
  39 #include <sys/mbuf.h>
  40 #include <sys/protosw.h>
  41 #include <sys/socket.h>
  42 #include <sys/socketvar.h>
  43 #include <sys/sysctl.h>
  44
  45 #include <net/if.h>
  46 #include <net/route.h>
  47
  48 #include <netinet/in.h>
  49 #include <netinet/in_systm.h>
  50 #include <netinet/in_var.h>
  51 #include <netinet/ip.h>
  52 #include <netinet/in_pcb.h>
  53 #include <netinet/ip_var.h>
  54 #include <netinet/ip_options.h>
  55
  56 #include <machine/in_cksum.h>
  57
  58 #ifdef IPSEC
  59 #include <netipsec/ipsec.h>
  60 #include <netipsec/ipsec6.h>
  61 #include <netipsec/xform.h>
  62 #include <netipsec/key.h>
  63 #ifdef IPSEC_DEBUG
  64 #include <netipsec/key_debug.h>
  65 #else
  66 #define KEYDEBUG(lev,arg)
  67 #endif
  68 #endif /*IPSEC*/
  69
  70 #include <netinet6/ip6_ipsec.h>
  71
  72 extern  struct protosw inet6sw[];
  73
  74 /*
  75  * Check if we have to jump over firewall processing for this packet.
  76  * Called from ip_input().
  77  * 1 = jump over firewall, 0 = packet goes through firewall.
  78  */
  79 int
  80 ip6_ipsec_filtertunnel(struct mbuf *m)
  81 {
  82 #if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL)
  83         /*
  84          * Bypass packet filtering for packets from a tunnel.
  85          */
  86         if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  87                 return 1;
  88 #endif
  89         return 0;
  90 }
  91
  92 /*
  93  * Check if this packet has an active SA and needs to be dropped instead
  94  * of forwarded.
  95  * Called from ip_input().
  96  * 1 = drop packet, 0 = forward packet.
  97  */
  98 int
  99 ip6_ipsec_fwd(struct mbuf *m)
 100 {
 101 #ifdef IPSEC
 102         struct m_tag *mtag;
 103         struct tdb_ident *tdbi;
 104         struct secpolicy *sp;
 105         int s, error;
 106         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 107         s = splnet();
 108         if (mtag != NULL) {
 109                 tdbi = (struct tdb_ident *)(mtag + 1);
 110                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 111         } else {
 112                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 113                                            IP_FORWARDING, &error);
 114         }
 115         if (sp == NULL) {       /* NB: can happen if error */
 116                 splx(s);
 117                 /*XXX error stat???*/
 118                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 119                 return 1;
 120         }
 121
 122         /*
 123          * Check security policy against packet attributes.
 124          */
 125         error = ipsec_in_reject(sp, m);
 126         KEY_FREESP(&sp);
 127         splx(s);
 128         if (error) {
 129                 ipstat.ips_cantforward++;
 130                 return 1;
 131         }
 132 #endif /* IPSEC */
 133         return 0;
 134 }
 135
 136 /*
 137  * Check if protocol type doesn't have a further header and do IPSEC
 138  * decryption or reject right now.  Protocols with further headers get
 139  * their IPSEC treatment within the protocol specific processing.
 140  * Called from ip_input().
 141  * 1 = drop packet, 0 = continue processing packet.
 142  */
 143 int
 144 ip6_ipsec_input(struct mbuf *m, int nxt)
 145 {
 146 #ifdef IPSEC
 147         struct m_tag *mtag;
 148         struct tdb_ident *tdbi;
 149         struct secpolicy *sp;
 150         int s, error;
 151         /*
 152          * enforce IPsec policy checking if we are seeing last header.
 153          * note that we do not visit this with protocols with pcb layer
 154          * code - like udp/tcp/raw ip.
 155          */
 156         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
 157             ipsec6_in_reject(m, NULL)) {
 158
 159                 /*
 160                  * Check if the packet has already had IPsec processing
 161                  * done.  If so, then just pass it along.  This tag gets
 162                  * set during AH, ESP, etc. input handling, before the
 163                  * packet is returned to the ip input queue for delivery.
 164                  */
 165                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 166                 s = splnet();
 167                 if (mtag != NULL) {
 168                         tdbi = (struct tdb_ident *)(mtag + 1);
 169                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 170                 } else {
 171                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 172                                                    IP_FORWARDING, &error);
 173                 }
 174                 if (sp != NULL) {
 175                         /*
 176                          * Check security policy against packet attributes.
 177                          */
 178                         error = ipsec_in_reject(sp, m);
 179                         KEY_FREESP(&sp);
 180                 } else {
 181                         /* XXX error stat??? */
 182                         error = EINVAL;
 183                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 184                         return 1;
 185                 }
 186                 splx(s);
 187                 if (error)
 188                         return 1;
 189         }
 190 #endif /* IPSEC */
 191         return 0;
 192 }
 193
 194 /*
 195  * Called from ip6_output().
 196  * 1 = drop packet, 0 = continue processing packet,
 197  * -1 = packet was reinjected and stop processing packet
 198  */
 199
 200 int
 201 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 202     struct ifnet **ifp, struct secpolicy **sp)
 203 {
 204 #ifdef IPSEC
 205         struct tdb_ident *tdbi;
 206         struct m_tag *mtag;
 207         /* XXX int s; */
 208         if (sp == NULL)
 209                 return 1;
 210         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 211         if (mtag != NULL) {
 212                 tdbi = (struct tdb_ident *)(mtag + 1);
 213                 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 214                 if (*sp == NULL)
 215                         *error = -EINVAL;       /* force silent drop */
 216                 m_tag_delete(*m, mtag);
 217         } else {
 218                 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 219                                         error, inp);
 220         }
 221
 222         /*
 223          * There are four return cases:
 224          *    sp != NULL                    apply IPsec policy
 225          *    sp == NULL, error == 0        no IPsec handling needed
 226          *    sp == NULL, error == -EINVAL  discard packet w/o error
 227          *    sp == NULL, error != 0        discard packet, report error
 228          */
 229         if (*sp != NULL) {
 230                 /* Loop detection, check if ipsec processing already done */
 231                 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
 232                 for (mtag = m_tag_first(*m); mtag != NULL;
 233                      mtag = m_tag_next(*m, mtag)) {
 234                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 235                                 continue;
 236                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 237                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 238                                 continue;
 239                         /*
 240                          * Check if policy has an SA associated with it.
 241                          * This can happen when an SP has yet to acquire
 242                          * an SA; e.g. on first reference.  If it occurs,
 243                          * then we let ipsec4_process_packet do its thing.
 244                          */
 245                         if ((*sp)->req->sav == NULL)
 246                                 break;
 247                         tdbi = (struct tdb_ident *)(mtag + 1);
 248                         if (tdbi->spi == (*sp)->req->sav->spi &&
 249                             tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
 250                             bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
 251                                  sizeof (union sockaddr_union)) == 0) {
 252                                 /*
 253                                  * No IPsec processing is needed, free
 254                                  * reference to SP.
 255                                  *
 256                                  * NB: null pointer to avoid free at
 257                                  *     done: below.
 258                                  */
 259                                 KEY_FREESP(sp), sp = NULL;
 260                                 /* XXX splx(s); */
 261                                 goto done;
 262                         }
 263                 }
 264
 265                 /*
 266                  * Do delayed checksums now because we send before
 267                  * this is done in the normal processing path.
 268                  */
 269                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 270                         in_delayed_cksum(*m);
 271                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 272                 }
 273
 274                 /*
 275                  * Preserve KAME behaviour: ENOENT can be returned
 276                  * when an SA acquire is in progress.  Don't propagate
 277                  * this to user-level; it confuses applications.
 278                  *
 279                  * XXX this will go away when the SADB is redone.
 280                  */
 281                 if (*error == ENOENT)
 282                         *error = 0;
 283                 goto do_ipsec;
 284         } else {        /* sp == NULL */
 285                 if (*error != 0) {
 286                         /*
 287                          * Hack: -EINVAL is used to signal that a packet
 288                          * should be silently discarded.  This is typically
 289                          * because we asked key management for an SA and
 290                          * it was delayed (e.g. kicked up to IKE).
 291                          */
 292                         if (*error == -EINVAL)
 293                                 *error = 0;
 294                         goto bad;
 295                 } else {
 296                         /* No IPsec processing for this packet. */
 297                 }
 298         }
 299 done:
 300         if (sp != NULL)
 301                 if (*sp != NULL)
 302                         KEY_FREESP(sp);
 303         return 0;
 304 do_ipsec:
 305         return -1;
 306 bad:
 307         if (sp != NULL)
 308                 if (*sp != NULL)
 309                         KEY_FREESP(sp);
 310         return 1;
 311 #endif /* IPSEC */
 312         return 0;
 313 }
 314
 315 /*
 316  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 317  * Called from ip_forward().
 318  * Returns MTU suggestion for ICMP needfrag reply.
 319  */
 320 int
 321 ip6_ipsec_mtu(struct mbuf *m)
 322 {
 323         int mtu = 0;
 324         /*
 325          * If the packet is routed over IPsec tunnel, tell the
 326          * originator the tunnel MTU.
 327          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 328          * XXX quickhack!!!
 329          */
 330         struct secpolicy *sp = NULL;
 331         int ipsecerror;
 332         int ipsechdr;
 333         struct route *ro;
 334 #ifdef IPSEC
 335         sp = ipsec_getpolicybyaddr(m,
 336                                    IPSEC_DIR_OUTBOUND,
 337                                    IP_FORWARDING,
 338                                    &ipsecerror);
 339 #endif /* IPSEC */
 340         if (sp != NULL) {
 341                 /* count IPsec header size */
 342                 ipsechdr = ipsec4_hdrsiz(m,
 343                                          IPSEC_DIR_OUTBOUND,
 344                                          NULL);
 345
 346                 /*
 347                  * find the correct route for outer IPv4
 348                  * header, compute tunnel MTU.
 349                  */
 350                 if (sp->req != NULL &&
 351                     sp->req->sav != NULL &&
 352                     sp->req->sav->sah != NULL) {
 353                         ro = &sp->req->sav->sah->sa_route;
 354                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 355                                 mtu =
 356                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 357                                     ro->ro_rt->rt_rmx.rmx_mtu :
 358                                     ro->ro_rt->rt_ifp->if_mtu;
 359                                 mtu -= ipsechdr;
 360                         }
 361                 }
 362 #ifdef IPSEC
 363                 KEY_FREESP(&sp);
 364 #endif /* IPSEC */
 365         }
 366         return mtu;
 367 }
 368