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 #include <netinet6/ip6_var.h>
  73
  74 extern  struct protosw inet6sw[];
  75
  76 /*
  77  * Check if we have to jump over firewall processing for this packet.
  78  * Called from ip_input().
  79  * 1 = jump over firewall, 0 = packet goes through firewall.
  80  */
  81 int
  82 ip6_ipsec_filtertunnel(struct mbuf *m)
  83 {
  84 #if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL)
  85         /*
  86          * Bypass packet filtering for packets from a tunnel.
  87          */
  88         if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  89                 return 1;
  90 #endif
  91         return 0;
  92 }
  93
  94 /*
  95  * Check if this packet has an active SA and needs to be dropped instead
  96  * of forwarded.
  97  * Called from ip_input().
  98  * 1 = drop packet, 0 = forward packet.
  99  */
 100 int
 101 ip6_ipsec_fwd(struct mbuf *m)
 102 {
 103 #ifdef IPSEC
 104         struct m_tag *mtag;
 105         struct tdb_ident *tdbi;
 106         struct secpolicy *sp;
 107         int s, error;
 108         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 109         s = splnet();
 110         if (mtag != NULL) {
 111                 tdbi = (struct tdb_ident *)(mtag + 1);
 112                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 113         } else {
 114                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 115                                            IP_FORWARDING, &error);
 116         }
 117         if (sp == NULL) {       /* NB: can happen if error */
 118                 splx(s);
 119                 /*XXX error stat???*/
 120                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 121                 return 1;
 122         }
 123
 124         /*
 125          * Check security policy against packet attributes.
 126          */
 127         error = ipsec_in_reject(sp, m);
 128         KEY_FREESP(&sp);
 129         splx(s);
 130         if (error) {
 131                 ip6stat.ip6s_cantforward++;
 132                 return 1;
 133         }
 134 #endif /* IPSEC */
 135         return 0;
 136 }
 137
 138 /*
 139  * Check if protocol type doesn't have a further header and do IPSEC
 140  * decryption or reject right now.  Protocols with further headers get
 141  * their IPSEC treatment within the protocol specific processing.
 142  * Called from ip_input().
 143  * 1 = drop packet, 0 = continue processing packet.
 144  */
 145 int
 146 ip6_ipsec_input(struct mbuf *m, int nxt)
 147 {
 148 #ifdef IPSEC
 149         struct m_tag *mtag;
 150         struct tdb_ident *tdbi;
 151         struct secpolicy *sp;
 152         int s, error;
 153         /*
 154          * enforce IPsec policy checking if we are seeing last header.
 155          * note that we do not visit this with protocols with pcb layer
 156          * code - like udp/tcp/raw ip.
 157          */
 158         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
 159             ipsec6_in_reject(m, NULL)) {
 160
 161                 /*
 162                  * Check if the packet has already had IPsec processing
 163                  * done.  If so, then just pass it along.  This tag gets
 164                  * set during AH, ESP, etc. input handling, before the
 165                  * packet is returned to the ip input queue for delivery.
 166                  */
 167                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 168                 s = splnet();
 169                 if (mtag != NULL) {
 170                         tdbi = (struct tdb_ident *)(mtag + 1);
 171                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 172                 } else {
 173                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 174                                                    IP_FORWARDING, &error);
 175                 }
 176                 if (sp != NULL) {
 177                         /*
 178                          * Check security policy against packet attributes.
 179                          */
 180                         error = ipsec_in_reject(sp, m);
 181                         KEY_FREESP(&sp);
 182                 } else {
 183                         /* XXX error stat??? */
 184                         error = EINVAL;
 185                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 186                         return 1;
 187                 }
 188                 splx(s);
 189                 if (error)
 190                         return 1;
 191         }
 192 #endif /* IPSEC */
 193         return 0;
 194 }
 195
 196 /*
 197  * Called from ip6_output().
 198  * 1 = drop packet, 0 = continue processing packet,
 199  * -1 = packet was reinjected and stop processing packet
 200  */
 201
 202 int
 203 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 204     struct ifnet **ifp, struct secpolicy **sp)
 205 {
 206 #ifdef IPSEC
 207         struct tdb_ident *tdbi;
 208         struct m_tag *mtag;
 209         /* XXX int s; */
 210         if (sp == NULL)
 211                 return 1;
 212         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 213         if (mtag != NULL) {
 214                 tdbi = (struct tdb_ident *)(mtag + 1);
 215                 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 216                 if (*sp == NULL)
 217                         *error = -EINVAL;       /* force silent drop */
 218                 m_tag_delete(*m, mtag);
 219         } else {
 220                 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 221                                         error, inp);
 222         }
 223
 224         /*
 225          * There are four return cases:
 226          *    sp != NULL                    apply IPsec policy
 227          *    sp == NULL, error == 0        no IPsec handling needed
 228          *    sp == NULL, error == -EINVAL  discard packet w/o error
 229          *    sp == NULL, error != 0        discard packet, report error
 230          */
 231         if (*sp != NULL) {
 232                 /* Loop detection, check if ipsec processing already done */
 233                 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
 234                 for (mtag = m_tag_first(*m); mtag != NULL;
 235                      mtag = m_tag_next(*m, mtag)) {
 236                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 237                                 continue;
 238                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 239                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 240                                 continue;
 241                         /*
 242                          * Check if policy has an SA associated with it.
 243                          * This can happen when an SP has yet to acquire
 244                          * an SA; e.g. on first reference.  If it occurs,
 245                          * then we let ipsec4_process_packet do its thing.
 246                          */
 247                         if ((*sp)->req->sav == NULL)
 248                                 break;
 249                         tdbi = (struct tdb_ident *)(mtag + 1);
 250                         if (tdbi->spi == (*sp)->req->sav->spi &&
 251                             tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
 252                             bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
 253                                  sizeof (union sockaddr_union)) == 0) {
 254                                 /*
 255                                  * No IPsec processing is needed, free
 256                                  * reference to SP.
 257                                  *
 258                                  * NB: null pointer to avoid free at
 259                                  *     done: below.
 260                                  */
 261                                 KEY_FREESP(sp), *sp = NULL;
 262                                 /* XXX splx(s); */
 263                                 goto done;
 264                         }
 265                 }
 266
 267                 /*
 268                  * Do delayed checksums now because we send before
 269                  * this is done in the normal processing path.
 270                  */
 271                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 272                         in_delayed_cksum(*m);
 273                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 274                 }
 275
 276                 /*
 277                  * Preserve KAME behaviour: ENOENT can be returned
 278                  * when an SA acquire is in progress.  Don't propagate
 279                  * this to user-level; it confuses applications.
 280                  *
 281                  * XXX this will go away when the SADB is redone.
 282                  */
 283                 if (*error == ENOENT)
 284                         *error = 0;
 285                 goto do_ipsec;
 286         } else {        /* sp == NULL */
 287                 if (*error != 0) {
 288                         /*
 289                          * Hack: -EINVAL is used to signal that a packet
 290                          * should be silently discarded.  This is typically
 291                          * because we asked key management for an SA and
 292                          * it was delayed (e.g. kicked up to IKE).
 293                          */
 294                         if (*error == -EINVAL)
 295                                 *error = 0;
 296                         goto bad;
 297                 } else {
 298                         /* No IPsec processing for this packet. */
 299                 }
 300         }
 301 done:
 302         return 0;
 303 do_ipsec:
 304         return -1;
 305 bad:
 306         return 1;
 307 #endif /* IPSEC */
 308         return 0;
 309 }
 310
 311 #if 0
 312 /*
 313  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 314  * Called from ip_forward().
 315  * Returns MTU suggestion for ICMP needfrag reply.
 316  */
 317 int
 318 ip6_ipsec_mtu(struct mbuf *m)
 319 {
 320         int mtu = 0;
 321         /*
 322          * If the packet is routed over IPsec tunnel, tell the
 323          * originator the tunnel MTU.
 324          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 325          * XXX quickhack!!!
 326          */
 327 #ifdef IPSEC
 328         struct secpolicy *sp = NULL;
 329         int ipsecerror;
 330         int ipsechdr;
 331         struct route *ro;
 332         sp = ipsec_getpolicybyaddr(m,
 333                                    IPSEC_DIR_OUTBOUND,
 334                                    IP_FORWARDING,
 335                                    &ipsecerror);
 336         if (sp != NULL) {
 337                 /* count IPsec header size */
 338                 ipsechdr = ipsec4_hdrsiz(m,
 339                                          IPSEC_DIR_OUTBOUND,
 340                                          NULL);
 341
 342                 /*
 343                  * find the correct route for outer IPv4
 344                  * header, compute tunnel MTU.
 345                  */
 346                 if (sp->req != NULL &&
 347                     sp->req->sav != NULL &&
 348                     sp->req->sav->sah != NULL) {
 349                         ro = &sp->req->sav->sah->sa_route;
 350                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 351                                 mtu =
 352                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 353                                     ro->ro_rt->rt_rmx.rmx_mtu :
 354                                     ro->ro_rt->rt_ifp->if_mtu;
 355                                 mtu -= ipsechdr;
 356                         }
 357                 }
 358                 KEY_FREESP(&sp);
 359         }
 360 #endif /* IPSEC */
 361         /* XXX else case missing. */
 362         return mtu;
 363 }
 364 #endif