sys/netinet/ip_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 #include "opt_sctp.h"
  35
  36 #include <sys/param.h>
  37 #include <sys/systm.h>
  38 #include <sys/errno.h>
  39 #include <sys/kernel.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/if_var.h>
  49 #include <net/route.h>
  50 #include <net/vnet.h>
  51
  52 #include <netinet/in.h>
  53 #include <netinet/in_systm.h>
  54 #include <netinet/in_var.h>
  55 #include <netinet/ip.h>
  56 #include <netinet/in_pcb.h>
  57 #include <netinet/ip_var.h>
  58 #include <netinet/ip_options.h>
  59 #include <netinet/ip_ipsec.h>
  60 #ifdef SCTP
  61 #include <netinet/sctp_crc32.h>
  62 #endif
  63
  64 #include <machine/in_cksum.h>
  65
  66 #ifdef IPSEC
  67 #include <netipsec/ipsec.h>
  68 #include <netipsec/xform.h>
  69 #include <netipsec/key.h>
  70 #endif /*IPSEC*/
  71
  72 extern  struct protosw inetsw[];
  73
  74 #ifdef IPSEC
  75 #ifdef IPSEC_FILTERTUNNEL
  76 static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 1;
  77 #else
  78 static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 0;
  79 #endif
  80 #define V_ip4_ipsec_filtertunnel VNET(ip4_ipsec_filtertunnel)
  81
  82 SYSCTL_DECL(_net_inet_ipsec);
  83 SYSCTL_VNET_INT(_net_inet_ipsec, OID_AUTO, filtertunnel,
  84         CTLFLAG_RW, &VNET_NAME(ip4_ipsec_filtertunnel), 0,
  85         "If set filter packets from an IPsec tunnel.");
  86 #endif /* IPSEC */
  87
  88 /*
  89  * Check if we have to jump over firewall processing for this packet.
  90  * Called from ip_input().
  91  * 1 = jump over firewall, 0 = packet goes through firewall.
  92  */
  93 int
  94 ip_ipsec_filtertunnel(struct mbuf *m)
  95 {
  96 #ifdef IPSEC
  97
  98         /*
  99          * Bypass packet filtering for packets previously handled by IPsec.
 100          */
 101         if (!V_ip4_ipsec_filtertunnel &&
 102             m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
 103                 return 1;
 104 #endif
 105         return 0;
 106 }
 107
 108 /*
 109  * Check if this packet has an active SA and needs to be dropped instead
 110  * of forwarded.
 111  * Called from ip_input().
 112  * 1 = drop packet, 0 = forward packet.
 113  */
 114 int
 115 ip_ipsec_fwd(struct mbuf *m)
 116 {
 117 #ifdef IPSEC
 118         struct m_tag *mtag;
 119         struct tdb_ident *tdbi;
 120         struct secpolicy *sp;
 121         int error;
 122
 123         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 124         if (mtag != NULL) {
 125                 tdbi = (struct tdb_ident *)(mtag + 1);
 126                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 127         } else {
 128                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 129                                            IP_FORWARDING, &error);
 130         }
 131         if (sp == NULL) {       /* NB: can happen if error */
 132                 /*XXX error stat???*/
 133                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 134                 return 1;
 135         }
 136
 137         /*
 138          * Check security policy against packet attributes.
 139          */
 140         error = ipsec_in_reject(sp, m);
 141         KEY_FREESP(&sp);
 142         if (error) {
 143                 IPSTAT_INC(ips_cantforward);
 144                 return 1;
 145         }
 146 #endif /* IPSEC */
 147         return 0;
 148 }
 149
 150 /*
 151  * Check if protocol type doesn't have a further header and do IPSEC
 152  * decryption or reject right now.  Protocols with further headers get
 153  * their IPSEC treatment within the protocol specific processing.
 154  * Called from ip_input().
 155  * 1 = drop packet, 0 = continue processing packet.
 156  */
 157 int
 158 ip_ipsec_input(struct mbuf *m)
 159 {
 160 #ifdef IPSEC
 161         struct ip *ip = mtod(m, struct ip *);
 162         struct m_tag *mtag;
 163         struct tdb_ident *tdbi;
 164         struct secpolicy *sp;
 165         int error;
 166         /*
 167          * enforce IPsec policy checking if we are seeing last header.
 168          * note that we do not visit this with protocols with pcb layer
 169          * code - like udp/tcp/raw ip.
 170          */
 171         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 172                 /*
 173                  * Check if the packet has already had IPsec processing
 174                  * done.  If so, then just pass it along.  This tag gets
 175                  * set during AH, ESP, etc. input handling, before the
 176                  * packet is returned to the ip input queue for delivery.
 177                  */
 178                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 179                 if (mtag != NULL) {
 180                         tdbi = (struct tdb_ident *)(mtag + 1);
 181                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 182                 } else {
 183                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 184                                                    IP_FORWARDING, &error);
 185                 }
 186                 if (sp != NULL) {
 187                         /*
 188                          * Check security policy against packet attributes.
 189                          */
 190                         error = ipsec_in_reject(sp, m);
 191                         KEY_FREESP(&sp);
 192                 } else {
 193                         /* XXX error stat??? */
 194                         error = EINVAL;
 195                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 196                         return 1;
 197                 }
 198                 if (error)
 199                         return 1;
 200         }
 201 #endif /* IPSEC */
 202         return 0;
 203 }
 204
 205 /*
 206  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 207  * Called from ip_forward().
 208  * Returns MTU suggestion for ICMP needfrag reply.
 209  */
 210 int
 211 ip_ipsec_mtu(struct mbuf *m, int mtu)
 212 {
 213         /*
 214          * If the packet is routed over IPsec tunnel, tell the
 215          * originator the tunnel MTU.
 216          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 217          * XXX quickhack!!!
 218          */
 219         struct secpolicy *sp = NULL;
 220         int ipsecerror;
 221         int ipsechdr;
 222         struct route *ro;
 223         sp = ipsec_getpolicybyaddr(m,
 224                                    IPSEC_DIR_OUTBOUND,
 225                                    IP_FORWARDING,
 226                                    &ipsecerror);
 227         if (sp != NULL) {
 228                 /* count IPsec header size */
 229                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
 230
 231                 /*
 232                  * find the correct route for outer IPv4
 233                  * header, compute tunnel MTU.
 234                  */
 235                 if (sp->req != NULL &&
 236                     sp->req->sav != NULL &&
 237                     sp->req->sav->sah != NULL) {
 238                         ro = &sp->req->sav->sah->route_cache.sa_route;
 239                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 240                                 mtu = ro->ro_rt->rt_mtu ? ro->ro_rt->rt_mtu :
 241                                     ro->ro_rt->rt_ifp->if_mtu;
 242                                 mtu -= ipsechdr;
 243                         }
 244                 }
 245                 KEY_FREESP(&sp);
 246         }
 247         return mtu;
 248 }
 249
 250 /*
 251  *
 252  * Called from ip_output().
 253  * 1 = drop packet, 0 = continue processing packet,
 254  * -1 = packet was reinjected and stop processing packet
 255  */
 256 int
 257 ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error)
 258 {
 259 #ifdef IPSEC
 260         struct secpolicy *sp = NULL;
 261         struct tdb_ident *tdbi;
 262         struct m_tag *mtag;
 263         /*
 264          * Check the security policy (SP) for the packet and, if
 265          * required, do IPsec-related processing.  There are two
 266          * cases here; the first time a packet is sent through
 267          * it will be untagged and handled by ipsec4_checkpolicy.
 268          * If the packet is resubmitted to ip_output (e.g. after
 269          * AH, ESP, etc. processing), there will be a tag to bypass
 270          * the lookup and related policy checking.
 271          */
 272         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 273         if (mtag != NULL) {
 274                 tdbi = (struct tdb_ident *)(mtag + 1);
 275                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 276                 if (sp == NULL)
 277                         *error = -EINVAL;       /* force silent drop */
 278                 m_tag_delete(*m, mtag);
 279         } else {
 280                 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 281                                         error, inp);
 282         }
 283         /*
 284          * There are four return cases:
 285          *    sp != NULL                    apply IPsec policy
 286          *    sp == NULL, error == 0        no IPsec handling needed
 287          *    sp == NULL, error == -EINVAL  discard packet w/o error
 288          *    sp == NULL, error != 0        discard packet, report error
 289          */
 290         if (sp != NULL) {
 291                 /* Loop detection, check if ipsec processing already done */
 292                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
 293                 for (mtag = m_tag_first(*m); mtag != NULL;
 294                      mtag = m_tag_next(*m, mtag)) {
 295                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 296                                 continue;
 297                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 298                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 299                                 continue;
 300                         /*
 301                          * Check if policy has an SA associated with it.
 302                          * This can happen when an SP has yet to acquire
 303                          * an SA; e.g. on first reference.  If it occurs,
 304                          * then we let ipsec4_process_packet do its thing.
 305                          */
 306                         if (sp->req->sav == NULL)
 307                                 break;
 308                         tdbi = (struct tdb_ident *)(mtag + 1);
 309                         if (tdbi->spi == sp->req->sav->spi &&
 310                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
 311                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
 312                                  sizeof (union sockaddr_union)) == 0) {
 313                                 /*
 314                                  * No IPsec processing is needed, free
 315                                  * reference to SP.
 316                                  *
 317                                  * NB: null pointer to avoid free at
 318                                  *     done: below.
 319                                  */
 320                                 KEY_FREESP(&sp), sp = NULL;
 321                                 goto done;
 322                         }
 323                 }
 324
 325                 /*
 326                  * Do delayed checksums now because we send before
 327                  * this is done in the normal processing path.
 328                  */
 329                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 330                         in_delayed_cksum(*m);
 331                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 332                 }
 333 #ifdef SCTP
 334                 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP) {
 335                         struct ip *ip = mtod(*m, struct ip *);
 336
 337                         sctp_delayed_cksum(*m, (uint32_t)(ip->ip_hl << 2));
 338                         (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP;
 339                 }
 340 #endif
 341
 342                 /* NB: callee frees mbuf */
 343                 *error = ipsec4_process_packet(*m, sp->req, *flags, 0);
 344                 if (*error == EJUSTRETURN) {
 345                         /*
 346                          * We had a SP with a level of 'use' and no SA. We
 347                          * will just continue to process the packet without
 348                          * IPsec processing and return without error.
 349                          */
 350                         *error = 0;
 351                         goto done;
 352                 }
 353                 /*
 354                  * Preserve KAME behaviour: ENOENT can be returned
 355                  * when an SA acquire is in progress.  Don't propagate
 356                  * this to user-level; it confuses applications.
 357                  *
 358                  * XXX this will go away when the SADB is redone.
 359                  */
 360                 if (*error == ENOENT)
 361                         *error = 0;
 362                 goto reinjected;
 363         } else {        /* sp == NULL */
 364
 365                 if (*error != 0) {
 366                         /*
 367                          * Hack: -EINVAL is used to signal that a packet
 368                          * should be silently discarded.  This is typically
 369                          * because we asked key management for an SA and
 370                          * it was delayed (e.g. kicked up to IKE).
 371                          */
 372                         if (*error == -EINVAL)
 373                                 *error = 0;
 374                         goto bad;
 375                 } else {
 376                         /* No IPsec processing for this packet. */
 377                 }
 378         }
 379 done:
 380         if (sp != NULL)
 381                 KEY_FREESP(&sp);
 382         return 0;
 383 reinjected:
 384         if (sp != NULL)
 385                 KEY_FREESP(&sp);
 386         return -1;
 387 bad:
 388         if (sp != NULL)
 389                 KEY_FREESP(&sp);
 390         return 1;
 391 #endif /* IPSEC */
 392         return 0;
 393 }