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_inet6.h"
  34 #include "opt_ipsec.h"
  35
  36 #include <sys/param.h>
  37 #include <sys/systm.h>
  38 #include <sys/kernel.h>
  39 #include <sys/mac.h>
  40 #include <sys/malloc.h>
  41 #include <sys/mbuf.h>
  42 #include <sys/protosw.h>
  43 #include <sys/socket.h>
  44 #include <sys/socketvar.h>
  45 #include <sys/sysctl.h>
  46
  47 #include <net/if.h>
  48 #include <net/route.h>
  49 #include <net/vnet.h>
  50
  51 #include <netinet/in.h>
  52 #include <netinet/in_systm.h>
  53 #include <netinet/in_var.h>
  54 #include <netinet/ip.h>
  55 #include <netinet/ip6.h>
  56 #include <netinet/in_pcb.h>
  57 #include <netinet/ip_var.h>
  58 #include <netinet/ip_options.h>
  59
  60 #include <machine/in_cksum.h>
  61
  62 #ifdef IPSEC
  63 #include <netipsec/ipsec.h>
  64 #include <netipsec/ipsec6.h>
  65 #include <netipsec/xform.h>
  66 #include <netipsec/key.h>
  67 #ifdef IPSEC_DEBUG
  68 #include <netipsec/key_debug.h>
  69 #else
  70 #define KEYDEBUG(lev,arg)
  71 #endif
  72 #endif /*IPSEC*/
  73
  74 #include <netinet6/ip6_ipsec.h>
  75 #include <netinet6/ip6_var.h>
  76
  77 extern  struct protosw inet6sw[];
  78
  79
  80 #ifdef INET6
  81 #ifdef IPSEC
  82 #ifdef IPSEC_FILTERTUNNEL
  83 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 1;
  84 #else
  85 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 0;
  86 #endif
  87 #define V_ip6_ipsec6_filtertunnel       VNET(ip6_ipsec6_filtertunnel)
  88
  89 SYSCTL_DECL(_net_inet6_ipsec6);
  90 SYSCTL_VNET_INT(_net_inet6_ipsec6, OID_AUTO,
  91         filtertunnel, CTLFLAG_RW, &VNET_NAME(ip6_ipsec6_filtertunnel),  0,
  92         "If set filter packets from an IPsec tunnel.");
  93 #endif /* IPSEC */
  94 #endif /* INET6 */
  95
  96 /*
  97  * Check if we have to jump over firewall processing for this packet.
  98  * Called from ip_input().
  99  * 1 = jump over firewall, 0 = packet goes through firewall.
 100  */
 101 int
 102 ip6_ipsec_filtertunnel(struct mbuf *m)
 103 {
 104 #if defined(IPSEC)
 105
 106         /*
 107          * Bypass packet filtering for packets from a tunnel.
 108          */
 109         if (!V_ip6_ipsec6_filtertunnel &&
 110             m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
 111                 return 1;
 112 #endif
 113         return 0;
 114 }
 115
 116 /*
 117  * Check if this packet has an active SA and needs to be dropped instead
 118  * of forwarded.
 119  * Called from ip_input().
 120  * 1 = drop packet, 0 = forward packet.
 121  */
 122 int
 123 ip6_ipsec_fwd(struct mbuf *m)
 124 {
 125 #ifdef IPSEC
 126         struct m_tag *mtag;
 127         struct tdb_ident *tdbi;
 128         struct secpolicy *sp;
 129         int s, error;
 130         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 131         s = splnet();
 132         if (mtag != NULL) {
 133                 tdbi = (struct tdb_ident *)(mtag + 1);
 134                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 135         } else {
 136                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 137                                            IP_FORWARDING, &error);
 138         }
 139         if (sp == NULL) {       /* NB: can happen if error */
 140                 splx(s);
 141                 /*XXX error stat???*/
 142                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 143                 return 1;
 144         }
 145
 146         /*
 147          * Check security policy against packet attributes.
 148          */
 149         error = ipsec_in_reject(sp, m);
 150         KEY_FREESP(&sp);
 151         splx(s);
 152         if (error) {
 153                 V_ip6stat.ip6s_cantforward++;
 154                 return 1;
 155         }
 156 #endif /* IPSEC */
 157         return 0;
 158 }
 159
 160 /*
 161  * Check if protocol type doesn't have a further header and do IPSEC
 162  * decryption or reject right now.  Protocols with further headers get
 163  * their IPSEC treatment within the protocol specific processing.
 164  * Called from ip_input().
 165  * 1 = drop packet, 0 = continue processing packet.
 166  */
 167 int
 168 ip6_ipsec_input(struct mbuf *m, int nxt)
 169 {
 170 #ifdef IPSEC
 171         struct m_tag *mtag;
 172         struct tdb_ident *tdbi;
 173         struct secpolicy *sp;
 174         int s, error;
 175         /*
 176          * enforce IPsec policy checking if we are seeing last header.
 177          * note that we do not visit this with protocols with pcb layer
 178          * code - like udp/tcp/raw ip.
 179          */
 180         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
 181             ipsec6_in_reject(m, NULL)) {
 182
 183                 /*
 184                  * Check if the packet has already had IPsec processing
 185                  * done.  If so, then just pass it along.  This tag gets
 186                  * set during AH, ESP, etc. input handling, before the
 187                  * packet is returned to the ip input queue for delivery.
 188                  */
 189                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 190                 s = splnet();
 191                 if (mtag != NULL) {
 192                         tdbi = (struct tdb_ident *)(mtag + 1);
 193                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 194                 } else {
 195                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 196                                                    IP_FORWARDING, &error);
 197                 }
 198                 if (sp != NULL) {
 199                         /*
 200                          * Check security policy against packet attributes.
 201                          */
 202                         error = ipsec_in_reject(sp, m);
 203                         KEY_FREESP(&sp);
 204                 } else {
 205                         /* XXX error stat??? */
 206                         error = EINVAL;
 207                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 208                         return 1;
 209                 }
 210                 splx(s);
 211                 if (error)
 212                         return 1;
 213         }
 214 #endif /* IPSEC */
 215         return 0;
 216 }
 217
 218 /*
 219  * Called from ip6_output().
 220  * 1 = drop packet, 0 = continue processing packet,
 221  * -1 = packet was reinjected and stop processing packet
 222  */
 223
 224 int
 225 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 226     struct ifnet **ifp, struct secpolicy **sp)
 227 {
 228 #ifdef IPSEC
 229         struct tdb_ident *tdbi;
 230         struct m_tag *mtag;
 231         /* XXX int s; */
 232         if (sp == NULL)
 233                 return 1;
 234         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 235         if (mtag != NULL) {
 236                 tdbi = (struct tdb_ident *)(mtag + 1);
 237                 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 238                 if (*sp == NULL)
 239                         *error = -EINVAL;       /* force silent drop */
 240                 m_tag_delete(*m, mtag);
 241         } else {
 242                 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 243                                         error, inp);
 244         }
 245
 246         /*
 247          * There are four return cases:
 248          *    sp != NULL                    apply IPsec policy
 249          *    sp == NULL, error == 0        no IPsec handling needed
 250          *    sp == NULL, error == -EINVAL  discard packet w/o error
 251          *    sp == NULL, error != 0        discard packet, report error
 252          */
 253         if (*sp != NULL) {
 254                 /* Loop detection, check if ipsec processing already done */
 255                 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
 256                 for (mtag = m_tag_first(*m); mtag != NULL;
 257                      mtag = m_tag_next(*m, mtag)) {
 258                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 259                                 continue;
 260                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 261                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 262                                 continue;
 263                         /*
 264                          * Check if policy has an SA associated with it.
 265                          * This can happen when an SP has yet to acquire
 266                          * an SA; e.g. on first reference.  If it occurs,
 267                          * then we let ipsec4_process_packet do its thing.
 268                          */
 269                         if ((*sp)->req->sav == NULL)
 270                                 break;
 271                         tdbi = (struct tdb_ident *)(mtag + 1);
 272                         if (tdbi->spi == (*sp)->req->sav->spi &&
 273                             tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
 274                             bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
 275                                  sizeof (union sockaddr_union)) == 0) {
 276                                 /*
 277                                  * No IPsec processing is needed, free
 278                                  * reference to SP.
 279                                  *
 280                                  * NB: null pointer to avoid free at
 281                                  *     done: below.
 282                                  */
 283                                 KEY_FREESP(sp), *sp = NULL;
 284                                 /* XXX splx(s); */
 285                                 goto done;
 286                         }
 287                 }
 288
 289                 /*
 290                  * Do delayed checksums now because we send before
 291                  * this is done in the normal processing path.
 292                  */
 293                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 294                         in_delayed_cksum(*m);
 295                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 296                 }
 297
 298                 /*
 299                  * Preserve KAME behaviour: ENOENT can be returned
 300                  * when an SA acquire is in progress.  Don't propagate
 301                  * this to user-level; it confuses applications.
 302                  *
 303                  * XXX this will go away when the SADB is redone.
 304                  */
 305                 if (*error == ENOENT)
 306                         *error = 0;
 307                 goto do_ipsec;
 308         } else {        /* sp == NULL */
 309                 if (*error != 0) {
 310                         /*
 311                          * Hack: -EINVAL is used to signal that a packet
 312                          * should be silently discarded.  This is typically
 313                          * because we asked key management for an SA and
 314                          * it was delayed (e.g. kicked up to IKE).
 315                          */
 316                         if (*error == -EINVAL)
 317                                 *error = 0;
 318                         goto bad;
 319                 } else {
 320                         /* No IPsec processing for this packet. */
 321                 }
 322         }
 323 done:
 324         return 0;
 325 do_ipsec:
 326         return -1;
 327 bad:
 328         return 1;
 329 #endif /* IPSEC */
 330         return 0;
 331 }
 332
 333 #if 0
 334 /*
 335  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 336  * Called from ip_forward().
 337  * Returns MTU suggestion for ICMP needfrag reply.
 338  */
 339 int
 340 ip6_ipsec_mtu(struct mbuf *m)
 341 {
 342         int mtu = 0;
 343         /*
 344          * If the packet is routed over IPsec tunnel, tell the
 345          * originator the tunnel MTU.
 346          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 347          * XXX quickhack!!!
 348          */
 349 #ifdef IPSEC
 350         struct secpolicy *sp = NULL;
 351         int ipsecerror;
 352         int ipsechdr;
 353         struct route *ro;
 354         sp = ipsec_getpolicybyaddr(m,
 355                                    IPSEC_DIR_OUTBOUND,
 356                                    IP_FORWARDING,
 357                                    &ipsecerror);
 358         if (sp != NULL) {
 359                 /* count IPsec header size */
 360                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
 361
 362                 /*
 363                  * find the correct route for outer IPv4
 364                  * header, compute tunnel MTU.
 365                  */
 366                 if (sp->req != NULL &&
 367                     sp->req->sav != NULL &&
 368                     sp->req->sav->sah != NULL) {
 369                         ro = &sp->req->sav->sah->sa_route;
 370                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 371                                 mtu =
 372                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 373                                     ro->ro_rt->rt_rmx.rmx_mtu :
 374                                     ro->ro_rt->rt_ifp->if_mtu;
 375                                 mtu -= ipsechdr;
 376                         }
 377                 }
 378                 KEY_FREESP(&sp);
 379         }
 380 #endif /* IPSEC */
 381         /* XXX else case missing. */
 382         return mtu;
 383 }
 384 #endif