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/errno.h>
  38 #include <sys/kernel.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 #include <sys/vimage.h>
  46
  47 #include <net/if.h>
  48 #include <net/route.h>
  49
  50 #include <netinet/in.h>
  51 #include <netinet/in_systm.h>
  52 #include <netinet/in_var.h>
  53 #include <netinet/ip.h>
  54 #include <netinet/in_pcb.h>
  55 #include <netinet/ip_var.h>
  56 #include <netinet/ip_options.h>
  57 #include <netinet/ip_ipsec.h>
  58 #include <netinet/vinet.h>
  59
  60 #include <machine/in_cksum.h>
  61
  62 #ifdef IPSEC
  63 #include <netipsec/ipsec.h>
  64 #include <netipsec/xform.h>
  65 #include <netipsec/key.h>
  66 #endif /*IPSEC*/
  67
  68 extern  struct protosw inetsw[];
  69
  70 /*
  71  * Check if we have to jump over firewall processing for this packet.
  72  * Called from ip_input().
  73  * 1 = jump over firewall, 0 = packet goes through firewall.
  74  */
  75 int
  76 ip_ipsec_filtertunnel(struct mbuf *m)
  77 {
  78 #if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL)
  79         /*
  80          * Bypass packet filtering for packets from a tunnel.
  81          */
  82         if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  83                 return 1;
  84 #endif
  85         return 0;
  86 }
  87
  88 /*
  89  * Check if this packet has an active SA and needs to be dropped instead
  90  * of forwarded.
  91  * Called from ip_input().
  92  * 1 = drop packet, 0 = forward packet.
  93  */
  94 int
  95 ip_ipsec_fwd(struct mbuf *m)
  96 {
  97 #ifdef IPSEC
  98         INIT_VNET_INET(curvnet);
  99         INIT_VNET_IPSEC(curvnet);
 100         struct m_tag *mtag;
 101         struct tdb_ident *tdbi;
 102         struct secpolicy *sp;
 103         int s, error;
 104
 105         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 106         s = splnet();
 107         if (mtag != NULL) {
 108                 tdbi = (struct tdb_ident *)(mtag + 1);
 109                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 110         } else {
 111                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 112                                            IP_FORWARDING, &error);
 113         }
 114         if (sp == NULL) {       /* NB: can happen if error */
 115                 splx(s);
 116                 /*XXX error stat???*/
 117                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 118                 return 1;
 119         }
 120
 121         /*
 122          * Check security policy against packet attributes.
 123          */
 124         error = ipsec_in_reject(sp, m);
 125         KEY_FREESP(&sp);
 126         splx(s);
 127         if (error) {
 128                 V_ipstat.ips_cantforward++;
 129                 return 1;
 130         }
 131 #endif /* IPSEC */
 132         return 0;
 133 }
 134
 135 /*
 136  * Check if protocol type doesn't have a further header and do IPSEC
 137  * decryption or reject right now.  Protocols with further headers get
 138  * their IPSEC treatment within the protocol specific processing.
 139  * Called from ip_input().
 140  * 1 = drop packet, 0 = continue processing packet.
 141  */
 142 int
 143 ip_ipsec_input(struct mbuf *m)
 144 {
 145         struct ip *ip = mtod(m, struct ip *);
 146 #ifdef IPSEC
 147         INIT_VNET_IPSEC(curvnet);
 148         struct m_tag *mtag;
 149         struct tdb_ident *tdbi;
 150         struct secpolicy *sp;
 151         int s, error;
 152         /*
 153          * enforce IPsec policy checking if we are seeing last header.
 154          * note that we do not visit this with protocols with pcb layer
 155          * code - like udp/tcp/raw ip.
 156          */
 157         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 158                 /*
 159                  * Check if the packet has already had IPsec processing
 160                  * done.  If so, then just pass it along.  This tag gets
 161                  * set during AH, ESP, etc. input handling, before the
 162                  * packet is returned to the ip input queue for delivery.
 163                  */
 164                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 165                 s = splnet();
 166                 if (mtag != NULL) {
 167                         tdbi = (struct tdb_ident *)(mtag + 1);
 168                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 169                 } else {
 170                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 171                                                    IP_FORWARDING, &error);
 172                 }
 173                 if (sp != NULL) {
 174                         /*
 175                          * Check security policy against packet attributes.
 176                          */
 177                         error = ipsec_in_reject(sp, m);
 178                         KEY_FREESP(&sp);
 179                 } else {
 180                         /* XXX error stat??? */
 181                         error = EINVAL;
 182                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 183                         return 1;
 184                 }
 185                 splx(s);
 186                 if (error)
 187                         return 1;
 188         }
 189 #endif /* IPSEC */
 190         return 0;
 191 }
 192
 193 /*
 194  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 195  * Called from ip_forward().
 196  * Returns MTU suggestion for ICMP needfrag reply.
 197  */
 198 int
 199 ip_ipsec_mtu(struct mbuf *m, int mtu)
 200 {
 201         /*
 202          * If the packet is routed over IPsec tunnel, tell the
 203          * originator the tunnel MTU.
 204          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 205          * XXX quickhack!!!
 206          */
 207         struct secpolicy *sp = NULL;
 208         int ipsecerror;
 209         int ipsechdr;
 210         struct route *ro;
 211         sp = ipsec_getpolicybyaddr(m,
 212                                    IPSEC_DIR_OUTBOUND,
 213                                    IP_FORWARDING,
 214                                    &ipsecerror);
 215         if (sp != NULL) {
 216                 /* count IPsec header size */
 217                 ipsechdr = ipsec4_hdrsiz(m,
 218                                          IPSEC_DIR_OUTBOUND,
 219                                          NULL);
 220
 221                 /*
 222                  * find the correct route for outer IPv4
 223                  * header, compute tunnel MTU.
 224                  */
 225                 if (sp->req != NULL &&
 226                     sp->req->sav != NULL &&
 227                     sp->req->sav->sah != NULL) {
 228                         ro = &sp->req->sav->sah->sa_route;
 229                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 230                                 mtu =
 231                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 232                                     ro->ro_rt->rt_rmx.rmx_mtu :
 233                                     ro->ro_rt->rt_ifp->if_mtu;
 234                                 mtu -= ipsechdr;
 235                         }
 236                 }
 237                 KEY_FREESP(&sp);
 238         }
 239         return mtu;
 240 }
 241
 242 /*
 243  *
 244  * Called from ip_output().
 245  * 1 = drop packet, 0 = continue processing packet,
 246  * -1 = packet was reinjected and stop processing packet
 247  */
 248 int
 249 ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 250     struct route **ro, struct route *iproute, struct sockaddr_in **dst,
 251     struct in_ifaddr **ia, struct ifnet **ifp)
 252 {
 253 #ifdef IPSEC
 254         struct secpolicy *sp = NULL;
 255         struct ip *ip = mtod(*m, struct ip *);
 256         struct tdb_ident *tdbi;
 257         struct m_tag *mtag;
 258         int s;
 259         /*
 260          * Check the security policy (SP) for the packet and, if
 261          * required, do IPsec-related processing.  There are two
 262          * cases here; the first time a packet is sent through
 263          * it will be untagged and handled by ipsec4_checkpolicy.
 264          * If the packet is resubmitted to ip_output (e.g. after
 265          * AH, ESP, etc. processing), there will be a tag to bypass
 266          * the lookup and related policy checking.
 267          */
 268         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 269         s = splnet();
 270         if (mtag != NULL) {
 271                 tdbi = (struct tdb_ident *)(mtag + 1);
 272                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 273                 if (sp == NULL)
 274                         *error = -EINVAL;       /* force silent drop */
 275                 m_tag_delete(*m, mtag);
 276         } else {
 277                 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 278                                         error, inp);
 279         }
 280         /*
 281          * There are four return cases:
 282          *    sp != NULL                    apply IPsec policy
 283          *    sp == NULL, error == 0        no IPsec handling needed
 284          *    sp == NULL, error == -EINVAL  discard packet w/o error
 285          *    sp == NULL, error != 0        discard packet, report error
 286          */
 287         if (sp != NULL) {
 288                 /* Loop detection, check if ipsec processing already done */
 289                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
 290                 for (mtag = m_tag_first(*m); mtag != NULL;
 291                      mtag = m_tag_next(*m, mtag)) {
 292                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 293                                 continue;
 294                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 295                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 296                                 continue;
 297                         /*
 298                          * Check if policy has an SA associated with it.
 299                          * This can happen when an SP has yet to acquire
 300                          * an SA; e.g. on first reference.  If it occurs,
 301                          * then we let ipsec4_process_packet do its thing.
 302                          */
 303                         if (sp->req->sav == NULL)
 304                                 break;
 305                         tdbi = (struct tdb_ident *)(mtag + 1);
 306                         if (tdbi->spi == sp->req->sav->spi &&
 307                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
 308                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
 309                                  sizeof (union sockaddr_union)) == 0) {
 310                                 /*
 311                                  * No IPsec processing is needed, free
 312                                  * reference to SP.
 313                                  *
 314                                  * NB: null pointer to avoid free at
 315                                  *     done: below.
 316                                  */
 317                                 KEY_FREESP(&sp), sp = NULL;
 318                                 splx(s);
 319                                 goto done;
 320                         }
 321                 }
 322
 323                 /*
 324                  * Do delayed checksums now because we send before
 325                  * this is done in the normal processing path.
 326                  */
 327                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 328                         in_delayed_cksum(*m);
 329                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 330                 }
 331
 332                 ip->ip_len = htons(ip->ip_len);
 333                 ip->ip_off = htons(ip->ip_off);
 334
 335                 /* NB: callee frees mbuf */
 336                 *error = ipsec4_process_packet(*m, sp->req, *flags, 0);
 337                 if (*error == EJUSTRETURN) {
 338                         /*
 339                          * We had a SP with a level of 'use' and no SA. We
 340                          * will just continue to process the packet without
 341                          * IPsec processing and return without error.
 342                          */
 343                         *error = 0;
 344                         ip->ip_len = ntohs(ip->ip_len);
 345                         ip->ip_off = ntohs(ip->ip_off);
 346                         goto done;
 347                 }
 348                 /*
 349                  * Preserve KAME behaviour: ENOENT can be returned
 350                  * when an SA acquire is in progress.  Don't propagate
 351                  * this to user-level; it confuses applications.
 352                  *
 353                  * XXX this will go away when the SADB is redone.
 354                  */
 355                 if (*error == ENOENT)
 356                         *error = 0;
 357                 splx(s);
 358                 goto reinjected;
 359         } else {        /* sp == NULL */
 360                 splx(s);
 361
 362                 if (*error != 0) {
 363                         /*
 364                          * Hack: -EINVAL is used to signal that a packet
 365                          * should be silently discarded.  This is typically
 366                          * because we asked key management for an SA and
 367                          * it was delayed (e.g. kicked up to IKE).
 368                          */
 369                         if (*error == -EINVAL)
 370                                 *error = 0;
 371                         goto bad;
 372                 } else {
 373                         /* No IPsec processing for this packet. */
 374                 }
 375 #ifdef notyet
 376                 /*
 377                  * If deferred crypto processing is needed, check that
 378                  * the interface supports it.
 379                  */
 380                 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED, NULL);
 381                 if (mtag != NULL && ((*ifp)->if_capenable & IFCAP_IPSEC) == 0) {
 382                         /* notify IPsec to do its own crypto */
 383                         ipsp_skipcrypto_unmark((struct tdb_ident *)(mtag + 1));
 384                         *error = EHOSTUNREACH;
 385                         goto bad;
 386                 }
 387 #endif
 388         }
 389 done:
 390         if (sp != NULL)
 391                 KEY_FREESP(&sp);
 392         return 0;
 393 reinjected:
 394         if (sp != NULL)
 395                 KEY_FREESP(&sp);
 396         return -1;
 397 bad:
 398         if (sp != NULL)
 399                 KEY_FREESP(&sp);
 400         return 1;
 401 #endif /* IPSEC */
 402         return 0;
 403 }