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
  35 #include <sys/param.h>
  36 #include <sys/systm.h>
  37 #include <sys/kernel.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 #include <netinet/ip_ipsec.h>
  56
  57 #include <machine/in_cksum.h>
  58
  59 #ifdef IPSEC
  60 #include <netipsec/ipsec.h>
  61 #include <netipsec/xform.h>
  62 #include <netipsec/key.h>
  63 #endif /*IPSEC*/
  64
  65 extern  struct protosw inetsw[];
  66
  67 /*
  68  * Check if we have to jump over firewall processing for this packet.
  69  * Called from ip_input().
  70  * 1 = jump over firewall, 0 = packet goes through firewall.
  71  */
  72 int
  73 ip_ipsec_filtertunnel(struct mbuf *m)
  74 {
  75 #if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL)
  76         /*
  77          * Bypass packet filtering for packets from a tunnel.
  78          */
  79         if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  80                 return 1;
  81 #endif
  82         return 0;
  83 }
  84
  85 /*
  86  * Check if this packet has an active SA and needs to be dropped instead
  87  * of forwarded.
  88  * Called from ip_input().
  89  * 1 = drop packet, 0 = forward packet.
  90  */
  91 int
  92 ip_ipsec_fwd(struct mbuf *m)
  93 {
  94 #ifdef IPSEC
  95         struct m_tag *mtag;
  96         struct tdb_ident *tdbi;
  97         struct secpolicy *sp;
  98         int s, error;
  99
 100         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 101         s = splnet();
 102         if (mtag != NULL) {
 103                 tdbi = (struct tdb_ident *)(mtag + 1);
 104                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 105         } else {
 106                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 107                                            IP_FORWARDING, &error);
 108         }
 109         if (sp == NULL) {       /* NB: can happen if error */
 110                 splx(s);
 111                 /*XXX error stat???*/
 112                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 113                 return 1;
 114         }
 115
 116         /*
 117          * Check security policy against packet attributes.
 118          */
 119         error = ipsec_in_reject(sp, m);
 120         KEY_FREESP(&sp);
 121         splx(s);
 122         if (error) {
 123                 ipstat.ips_cantforward++;
 124                 return 1;
 125         }
 126 #endif /* IPSEC */
 127         return 0;
 128 }
 129
 130 /*
 131  * Check if protocol type doesn't have a further header and do IPSEC
 132  * decryption or reject right now.  Protocols with further headers get
 133  * their IPSEC treatment within the protocol specific processing.
 134  * Called from ip_input().
 135  * 1 = drop packet, 0 = continue processing packet.
 136  */
 137 int
 138 ip_ipsec_input(struct mbuf *m)
 139 {
 140         struct ip *ip = mtod(m, struct ip *);
 141 #ifdef IPSEC
 142         struct m_tag *mtag;
 143         struct tdb_ident *tdbi;
 144         struct secpolicy *sp;
 145         int s, error;
 146         /*
 147          * enforce IPsec policy checking if we are seeing last header.
 148          * note that we do not visit this with protocols with pcb layer
 149          * code - like udp/tcp/raw ip.
 150          */
 151         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 152                 /*
 153                  * Check if the packet has already had IPsec processing
 154                  * done.  If so, then just pass it along.  This tag gets
 155                  * set during AH, ESP, etc. input handling, before the
 156                  * packet is returned to the ip input queue for delivery.
 157                  */
 158                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 159                 s = splnet();
 160                 if (mtag != NULL) {
 161                         tdbi = (struct tdb_ident *)(mtag + 1);
 162                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 163                 } else {
 164                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 165                                                    IP_FORWARDING, &error);
 166                 }
 167                 if (sp != NULL) {
 168                         /*
 169                          * Check security policy against packet attributes.
 170                          */
 171                         error = ipsec_in_reject(sp, m);
 172                         KEY_FREESP(&sp);
 173                 } else {
 174                         /* XXX error stat??? */
 175                         error = EINVAL;
 176                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 177                         return 1;
 178                 }
 179                 splx(s);
 180                 if (error)
 181                         return 1;
 182         }
 183 #endif /* IPSEC */
 184         return 0;
 185 }
 186
 187 /*
 188  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 189  * Called from ip_forward().
 190  * Returns MTU suggestion for ICMP needfrag reply.
 191  */
 192 int
 193 ip_ipsec_mtu(struct mbuf *m)
 194 {
 195         int mtu = 0;
 196         /*
 197          * If the packet is routed over IPsec tunnel, tell the
 198          * originator the tunnel MTU.
 199          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 200          * XXX quickhack!!!
 201          */
 202         struct secpolicy *sp = NULL;
 203         int ipsecerror;
 204         int ipsechdr;
 205         struct route *ro;
 206         sp = ipsec_getpolicybyaddr(m,
 207                                    IPSEC_DIR_OUTBOUND,
 208                                    IP_FORWARDING,
 209                                    &ipsecerror);
 210         if (sp != NULL) {
 211                 /* count IPsec header size */
 212                 ipsechdr = ipsec4_hdrsiz(m,
 213                                          IPSEC_DIR_OUTBOUND,
 214                                          NULL);
 215
 216                 /*
 217                  * find the correct route for outer IPv4
 218                  * header, compute tunnel MTU.
 219                  */
 220                 if (sp->req != NULL &&
 221                     sp->req->sav != NULL &&
 222                     sp->req->sav->sah != NULL) {
 223                         ro = &sp->req->sav->sah->sa_route;
 224                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 225                                 mtu =
 226                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 227                                     ro->ro_rt->rt_rmx.rmx_mtu :
 228                                     ro->ro_rt->rt_ifp->if_mtu;
 229                                 mtu -= ipsechdr;
 230                         }
 231                 }
 232                 KEY_FREESP(&sp);
 233         }
 234         return mtu;
 235 }
 236
 237 /*
 238  *
 239  * Called from ip_output().
 240  * 1 = drop packet, 0 = continue processing packet,
 241  * -1 = packet was reinjected and stop processing packet
 242  */
 243 int
 244 ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 245     struct route **ro, struct route *iproute, struct sockaddr_in **dst,
 246     struct in_ifaddr **ia, struct ifnet **ifp)
 247 {
 248 #ifdef IPSEC
 249         struct secpolicy *sp = NULL;
 250         struct ip *ip = mtod(*m, struct ip *);
 251         struct tdb_ident *tdbi;
 252         struct m_tag *mtag;
 253         int s;
 254         /*
 255          * Check the security policy (SP) for the packet and, if
 256          * required, do IPsec-related processing.  There are two
 257          * cases here; the first time a packet is sent through
 258          * it will be untagged and handled by ipsec4_checkpolicy.
 259          * If the packet is resubmitted to ip_output (e.g. after
 260          * AH, ESP, etc. processing), there will be a tag to bypass
 261          * the lookup and related policy checking.
 262          */
 263         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 264         s = splnet();
 265         if (mtag != NULL) {
 266                 tdbi = (struct tdb_ident *)(mtag + 1);
 267                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 268                 if (sp == NULL)
 269                         *error = -EINVAL;       /* force silent drop */
 270                 m_tag_delete(*m, mtag);
 271         } else {
 272                 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 273                                         error, inp);
 274         }
 275         /*
 276          * There are four return cases:
 277          *    sp != NULL                    apply IPsec policy
 278          *    sp == NULL, error == 0        no IPsec handling needed
 279          *    sp == NULL, error == -EINVAL  discard packet w/o error
 280          *    sp == NULL, error != 0        discard packet, report error
 281          */
 282         if (sp != NULL) {
 283                 /* Loop detection, check if ipsec processing already done */
 284                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
 285                 for (mtag = m_tag_first(*m); mtag != NULL;
 286                      mtag = m_tag_next(*m, mtag)) {
 287                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 288                                 continue;
 289                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 290                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 291                                 continue;
 292                         /*
 293                          * Check if policy has an SA associated with it.
 294                          * This can happen when an SP has yet to acquire
 295                          * an SA; e.g. on first reference.  If it occurs,
 296                          * then we let ipsec4_process_packet do its thing.
 297                          */
 298                         if (sp->req->sav == NULL)
 299                                 break;
 300                         tdbi = (struct tdb_ident *)(mtag + 1);
 301                         if (tdbi->spi == sp->req->sav->spi &&
 302                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
 303                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
 304                                  sizeof (union sockaddr_union)) == 0) {
 305                                 /*
 306                                  * No IPsec processing is needed, free
 307                                  * reference to SP.
 308                                  *
 309                                  * NB: null pointer to avoid free at
 310                                  *     done: below.
 311                                  */
 312                                 KEY_FREESP(&sp), sp = NULL;
 313                                 splx(s);
 314                                 goto done;
 315                         }
 316                 }
 317
 318                 /*
 319                  * Do delayed checksums now because we send before
 320                  * this is done in the normal processing path.
 321                  */
 322                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 323                         in_delayed_cksum(*m);
 324                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 325                 }
 326
 327                 ip->ip_len = htons(ip->ip_len);
 328                 ip->ip_off = htons(ip->ip_off);
 329
 330                 /* NB: callee frees mbuf */
 331                 *error = ipsec4_process_packet(*m, sp->req, *flags, 0);
 332                 /*
 333                  * Preserve KAME behaviour: ENOENT can be returned
 334                  * when an SA acquire is in progress.  Don't propagate
 335                  * this to user-level; it confuses applications.
 336                  *
 337                  * XXX this will go away when the SADB is redone.
 338                  */
 339                 if (*error == ENOENT)
 340                         *error = 0;
 341                 splx(s);
 342                 goto reinjected;
 343         } else {        /* sp == NULL */
 344                 splx(s);
 345
 346                 if (*error != 0) {
 347                         /*
 348                          * Hack: -EINVAL is used to signal that a packet
 349                          * should be silently discarded.  This is typically
 350                          * because we asked key management for an SA and
 351                          * it was delayed (e.g. kicked up to IKE).
 352                          */
 353                         if (*error == -EINVAL)
 354                                 *error = 0;
 355                         goto bad;
 356                 } else {
 357                         /* No IPsec processing for this packet. */
 358                 }
 359 #ifdef notyet
 360                 /*
 361                  * If deferred crypto processing is needed, check that
 362                  * the interface supports it.
 363                  */
 364                 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED, NULL);
 365                 if (mtag != NULL && ((*ifp)->if_capenable & IFCAP_IPSEC) == 0) {
 366                         /* notify IPsec to do its own crypto */
 367                         ipsp_skipcrypto_unmark((struct tdb_ident *)(mtag + 1));
 368                         *error = EHOSTUNREACH;
 369                         goto bad;
 370                 }
 371 #endif
 372         }
 373 done:
 374         if (sp != NULL)
 375                 KEY_FREESP(&sp);
 376         return 0;
 377 reinjected:
 378         if (sp != NULL)
 379                 KEY_FREESP(&sp);
 380         return -1;
 381 bad:
 382         if (sp != NULL)
 383                 KEY_FREESP(&sp);
 384         return 1;
 385 #endif /* IPSEC */
 386         return 0;
 387 }