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/ip6.h>
  54 #include <netinet/in_pcb.h>
  55 #include <netinet/ip_var.h>
  56 #include <netinet/ip_options.h>
  57
  58 #include <machine/in_cksum.h>
  59
  60 #ifdef IPSEC
  61 #include <netipsec/ipsec.h>
  62 #include <netipsec/ipsec6.h>
  63 #include <netipsec/xform.h>
  64 #include <netipsec/key.h>
  65 #ifdef IPSEC_DEBUG
  66 #include <netipsec/key_debug.h>
  67 #else
  68 #define KEYDEBUG(lev,arg)
  69 #endif
  70 #endif /*IPSEC*/
  71
  72 #include <netinet6/ip6_ipsec.h>
  73 #include <netinet6/ip6_var.h>
  74
  75 extern  struct protosw inet6sw[];
  76
  77 /*
  78  * Check if we have to jump over firewall processing for this packet.
  79  * Called from ip_input().
  80  * 1 = jump over firewall, 0 = packet goes through firewall.
  81  */
  82 int
  83 ip6_ipsec_filtertunnel(struct mbuf *m)
  84 {
  85 #if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL)
  86         /*
  87          * Bypass packet filtering for packets from a tunnel.
  88          */
  89         if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  90                 return 1;
  91 #endif
  92         return 0;
  93 }
  94
  95 /*
  96  * Check if this packet has an active SA and needs to be dropped instead
  97  * of forwarded.
  98  * Called from ip_input().
  99  * 1 = drop packet, 0 = forward packet.
 100  */
 101 int
 102 ip6_ipsec_fwd(struct mbuf *m)
 103 {
 104 #ifdef IPSEC
 105         struct m_tag *mtag;
 106         struct tdb_ident *tdbi;
 107         struct secpolicy *sp;
 108         int s, error;
 109         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 110         s = splnet();
 111         if (mtag != NULL) {
 112                 tdbi = (struct tdb_ident *)(mtag + 1);
 113                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 114         } else {
 115                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 116                                            IP_FORWARDING, &error);
 117         }
 118         if (sp == NULL) {       /* NB: can happen if error */
 119                 splx(s);
 120                 /*XXX error stat???*/
 121                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 122                 return 1;
 123         }
 124
 125         /*
 126          * Check security policy against packet attributes.
 127          */
 128         error = ipsec_in_reject(sp, m);
 129         KEY_FREESP(&sp);
 130         splx(s);
 131         if (error) {
 132                 ip6stat.ip6s_cantforward++;
 133                 return 1;
 134         }
 135 #endif /* IPSEC */
 136         return 0;
 137 }
 138
 139 /*
 140  * Check if protocol type doesn't have a further header and do IPSEC
 141  * decryption or reject right now.  Protocols with further headers get
 142  * their IPSEC treatment within the protocol specific processing.
 143  * Called from ip_input().
 144  * 1 = drop packet, 0 = continue processing packet.
 145  */
 146 int
 147 ip6_ipsec_input(struct mbuf *m, int nxt)
 148 {
 149 #ifdef IPSEC
 150         struct m_tag *mtag;
 151         struct tdb_ident *tdbi;
 152         struct secpolicy *sp;
 153         int s, error;
 154         /*
 155          * enforce IPsec policy checking if we are seeing last header.
 156          * note that we do not visit this with protocols with pcb layer
 157          * code - like udp/tcp/raw ip.
 158          */
 159         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
 160             ipsec6_in_reject(m, NULL)) {
 161
 162                 /*
 163                  * Check if the packet has already had IPsec processing
 164                  * done.  If so, then just pass it along.  This tag gets
 165                  * set during AH, ESP, etc. input handling, before the
 166                  * packet is returned to the ip input queue for delivery.
 167                  */
 168                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 169                 s = splnet();
 170                 if (mtag != NULL) {
 171                         tdbi = (struct tdb_ident *)(mtag + 1);
 172                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 173                 } else {
 174                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 175                                                    IP_FORWARDING, &error);
 176                 }
 177                 if (sp != NULL) {
 178                         /*
 179                          * Check security policy against packet attributes.
 180                          */
 181                         error = ipsec_in_reject(sp, m);
 182                         KEY_FREESP(&sp);
 183                 } else {
 184                         /* XXX error stat??? */
 185                         error = EINVAL;
 186                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 187                         return 1;
 188                 }
 189                 splx(s);
 190                 if (error)
 191                         return 1;
 192         }
 193 #endif /* IPSEC */
 194         return 0;
 195 }
 196
 197 /*
 198  * Called from ip6_output().
 199  * 1 = drop packet, 0 = continue processing packet,
 200  * -1 = packet was reinjected and stop processing packet
 201  */
 202
 203 int
 204 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 205     struct ifnet **ifp, struct secpolicy **sp)
 206 {
 207 #ifdef IPSEC
 208         struct tdb_ident *tdbi;
 209         struct m_tag *mtag;
 210         /* XXX int s; */
 211         if (sp == NULL)
 212                 return 1;
 213         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 214         if (mtag != NULL) {
 215                 tdbi = (struct tdb_ident *)(mtag + 1);
 216                 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 217                 if (*sp == NULL)
 218                         *error = -EINVAL;       /* force silent drop */
 219                 m_tag_delete(*m, mtag);
 220         } else {
 221                 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 222                                         error, inp);
 223         }
 224
 225         /*
 226          * There are four return cases:
 227          *    sp != NULL                    apply IPsec policy
 228          *    sp == NULL, error == 0        no IPsec handling needed
 229          *    sp == NULL, error == -EINVAL  discard packet w/o error
 230          *    sp == NULL, error != 0        discard packet, report error
 231          */
 232         if (*sp != NULL) {
 233                 /* Loop detection, check if ipsec processing already done */
 234                 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
 235                 for (mtag = m_tag_first(*m); mtag != NULL;
 236                      mtag = m_tag_next(*m, mtag)) {
 237                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 238                                 continue;
 239                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 240                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 241                                 continue;
 242                         /*
 243                          * Check if policy has an SA associated with it.
 244                          * This can happen when an SP has yet to acquire
 245                          * an SA; e.g. on first reference.  If it occurs,
 246                          * then we let ipsec4_process_packet do its thing.
 247                          */
 248                         if ((*sp)->req->sav == NULL)
 249                                 break;
 250                         tdbi = (struct tdb_ident *)(mtag + 1);
 251                         if (tdbi->spi == (*sp)->req->sav->spi &&
 252                             tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
 253                             bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
 254                                  sizeof (union sockaddr_union)) == 0) {
 255                                 /*
 256                                  * No IPsec processing is needed, free
 257                                  * reference to SP.
 258                                  *
 259                                  * NB: null pointer to avoid free at
 260                                  *     done: below.
 261                                  */
 262                                 KEY_FREESP(sp), *sp = NULL;
 263                                 /* XXX splx(s); */
 264                                 goto done;
 265                         }
 266                 }
 267
 268                 /*
 269                  * Do delayed checksums now because we send before
 270                  * this is done in the normal processing path.
 271                  */
 272                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 273                         in_delayed_cksum(*m);
 274                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 275                 }
 276
 277                 /*
 278                  * Preserve KAME behaviour: ENOENT can be returned
 279                  * when an SA acquire is in progress.  Don't propagate
 280                  * this to user-level; it confuses applications.
 281                  *
 282                  * XXX this will go away when the SADB is redone.
 283                  */
 284                 if (*error == ENOENT)
 285                         *error = 0;
 286                 goto do_ipsec;
 287         } else {        /* sp == NULL */
 288                 if (*error != 0) {
 289                         /*
 290                          * Hack: -EINVAL is used to signal that a packet
 291                          * should be silently discarded.  This is typically
 292                          * because we asked key management for an SA and
 293                          * it was delayed (e.g. kicked up to IKE).
 294                          */
 295                         if (*error == -EINVAL)
 296                                 *error = 0;
 297                         goto bad;
 298                 } else {
 299                         /* No IPsec processing for this packet. */
 300                 }
 301         }
 302 done:
 303         return 0;
 304 do_ipsec:
 305         return -1;
 306 bad:
 307         return 1;
 308 #endif /* IPSEC */
 309         return 0;
 310 }
 311
 312 #if 0
 313 /*
 314  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 315  * Called from ip_forward().
 316  * Returns MTU suggestion for ICMP needfrag reply.
 317  */
 318 int
 319 ip6_ipsec_mtu(struct mbuf *m)
 320 {
 321         int mtu = 0;
 322         /*
 323          * If the packet is routed over IPsec tunnel, tell the
 324          * originator the tunnel MTU.
 325          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 326          * XXX quickhack!!!
 327          */
 328 #ifdef IPSEC
 329         struct secpolicy *sp = NULL;
 330         int ipsecerror;
 331         int ipsechdr;
 332         struct route *ro;
 333         sp = ipsec_getpolicybyaddr(m,
 334                                    IPSEC_DIR_OUTBOUND,
 335                                    IP_FORWARDING,
 336                                    &ipsecerror);
 337         if (sp != NULL) {
 338                 /* count IPsec header size */
 339                 ipsechdr = ipsec4_hdrsiz(m,
 340                                          IPSEC_DIR_OUTBOUND,
 341                                          NULL);
 342
 343                 /*
 344                  * find the correct route for outer IPv4
 345                  * header, compute tunnel MTU.
 346                  */
 347                 if (sp->req != NULL &&
 348                     sp->req->sav != NULL &&
 349                     sp->req->sav->sah != NULL) {
 350                         ro = &sp->req->sav->sah->sa_route;
 351                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 352                                 mtu =
 353                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 354                                     ro->ro_rt->rt_rmx.rmx_mtu :
 355                                     ro->ro_rt->rt_ifp->if_mtu;
 356                                 mtu -= ipsechdr;
 357                         }
 358                 }
 359                 KEY_FREESP(&sp);
 360         }
 361 #endif /* IPSEC */
 362         /* XXX else case missing. */
 363         return mtu;
 364 }
 365 #endif