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 #include <sys/vimage.h>
  47
  48 #include <net/if.h>
  49 #include <net/route.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/in_pcb.h>
  56 #include <netinet/ip_var.h>
  57 #include <netinet/ip_options.h>
  58 #include <netinet/ip_ipsec.h>
  59 #include <netinet/vinet.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 VIMAGE_GLOBALS
  75 int ip4_ipsec_filtertunnel;
  76 #endif
  77
  78 /*
  79  * Check if we have to jump over firewall processing for this packet.
  80  * Called from ip_input().
  81  * 1 = jump over firewall, 0 = packet goes through firewall.
  82  */
  83 int
  84 ip_ipsec_filtertunnel(struct mbuf *m)
  85 {
  86 #if defined(IPSEC)
  87         INIT_VNET_IPSEC(curvnet);
  88
  89         /*
  90          * Bypass packet filtering for packets from a tunnel.
  91          */
  92         if (!V_ip4_ipsec_filtertunnel &&
  93             m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  94                 return 1;
  95 #endif
  96         return 0;
  97 }
  98
  99 /*
 100  * Check if this packet has an active SA and needs to be dropped instead
 101  * of forwarded.
 102  * Called from ip_input().
 103  * 1 = drop packet, 0 = forward packet.
 104  */
 105 int
 106 ip_ipsec_fwd(struct mbuf *m)
 107 {
 108 #ifdef IPSEC
 109         INIT_VNET_INET(curvnet);
 110         INIT_VNET_IPSEC(curvnet);
 111         struct m_tag *mtag;
 112         struct tdb_ident *tdbi;
 113         struct secpolicy *sp;
 114         int s, error;
 115
 116         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 117         s = splnet();
 118         if (mtag != NULL) {
 119                 tdbi = (struct tdb_ident *)(mtag + 1);
 120                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 121         } else {
 122                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 123                                            IP_FORWARDING, &error);
 124         }
 125         if (sp == NULL) {       /* NB: can happen if error */
 126                 splx(s);
 127                 /*XXX error stat???*/
 128                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 129                 return 1;
 130         }
 131
 132         /*
 133          * Check security policy against packet attributes.
 134          */
 135         error = ipsec_in_reject(sp, m);
 136         KEY_FREESP(&sp);
 137         splx(s);
 138         if (error) {
 139                 IPSTAT_INC(ips_cantforward);
 140                 return 1;
 141         }
 142 #endif /* IPSEC */
 143         return 0;
 144 }
 145
 146 /*
 147  * Check if protocol type doesn't have a further header and do IPSEC
 148  * decryption or reject right now.  Protocols with further headers get
 149  * their IPSEC treatment within the protocol specific processing.
 150  * Called from ip_input().
 151  * 1 = drop packet, 0 = continue processing packet.
 152  */
 153 int
 154 ip_ipsec_input(struct mbuf *m)
 155 {
 156         struct ip *ip = mtod(m, struct ip *);
 157 #ifdef IPSEC
 158         INIT_VNET_IPSEC(curvnet);
 159         struct m_tag *mtag;
 160         struct tdb_ident *tdbi;
 161         struct secpolicy *sp;
 162         int s, error;
 163         /*
 164          * enforce IPsec policy checking if we are seeing last header.
 165          * note that we do not visit this with protocols with pcb layer
 166          * code - like udp/tcp/raw ip.
 167          */
 168         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 169                 /*
 170                  * Check if the packet has already had IPsec processing
 171                  * done.  If so, then just pass it along.  This tag gets
 172                  * set during AH, ESP, etc. input handling, before the
 173                  * packet is returned to the ip input queue for delivery.
 174                  */
 175                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 176                 s = splnet();
 177                 if (mtag != NULL) {
 178                         tdbi = (struct tdb_ident *)(mtag + 1);
 179                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 180                 } else {
 181                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 182                                                    IP_FORWARDING, &error);
 183                 }
 184                 if (sp != NULL) {
 185                         /*
 186                          * Check security policy against packet attributes.
 187                          */
 188                         error = ipsec_in_reject(sp, m);
 189                         KEY_FREESP(&sp);
 190                 } else {
 191                         /* XXX error stat??? */
 192                         error = EINVAL;
 193                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 194                         return 1;
 195                 }
 196                 splx(s);
 197                 if (error)
 198                         return 1;
 199         }
 200 #endif /* IPSEC */
 201         return 0;
 202 }
 203
 204 /*
 205  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 206  * Called from ip_forward().
 207  * Returns MTU suggestion for ICMP needfrag reply.
 208  */
 209 int
 210 ip_ipsec_mtu(struct mbuf *m, int mtu)
 211 {
 212         /*
 213          * If the packet is routed over IPsec tunnel, tell the
 214          * originator the tunnel MTU.
 215          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 216          * XXX quickhack!!!
 217          */
 218         struct secpolicy *sp = NULL;
 219         int ipsecerror;
 220         int ipsechdr;
 221         struct route *ro;
 222         sp = ipsec_getpolicybyaddr(m,
 223                                    IPSEC_DIR_OUTBOUND,
 224                                    IP_FORWARDING,
 225                                    &ipsecerror);
 226         if (sp != NULL) {
 227                 /* count IPsec header size */
 228                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
 229
 230                 /*
 231                  * find the correct route for outer IPv4
 232                  * header, compute tunnel MTU.
 233                  */
 234                 if (sp->req != NULL &&
 235                     sp->req->sav != NULL &&
 236                     sp->req->sav->sah != NULL) {
 237                         ro = &sp->req->sav->sah->sa_route;
 238                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 239                                 mtu =
 240                                     ro->ro_rt->rt_rmx.rmx_mtu ?
 241                                     ro->ro_rt->rt_rmx.rmx_mtu :
 242                                     ro->ro_rt->rt_ifp->if_mtu;
 243                                 mtu -= ipsechdr;
 244                         }
 245                 }
 246                 KEY_FREESP(&sp);
 247         }
 248         return mtu;
 249 }
 250
 251 /*
 252  *
 253  * Called from ip_output().
 254  * 1 = drop packet, 0 = continue processing packet,
 255  * -1 = packet was reinjected and stop processing packet
 256  */
 257 int
 258 ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 259     struct ifnet **ifp)
 260 {
 261 #ifdef IPSEC
 262         struct secpolicy *sp = NULL;
 263         struct ip *ip = mtod(*m, struct ip *);
 264         struct tdb_ident *tdbi;
 265         struct m_tag *mtag;
 266         int s;
 267         /*
 268          * Check the security policy (SP) for the packet and, if
 269          * required, do IPsec-related processing.  There are two
 270          * cases here; the first time a packet is sent through
 271          * it will be untagged and handled by ipsec4_checkpolicy.
 272          * If the packet is resubmitted to ip_output (e.g. after
 273          * AH, ESP, etc. processing), there will be a tag to bypass
 274          * the lookup and related policy checking.
 275          */
 276         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 277         s = splnet();
 278         if (mtag != NULL) {
 279                 tdbi = (struct tdb_ident *)(mtag + 1);
 280                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 281                 if (sp == NULL)
 282                         *error = -EINVAL;       /* force silent drop */
 283                 m_tag_delete(*m, mtag);
 284         } else {
 285                 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 286                                         error, inp);
 287         }
 288         /*
 289          * There are four return cases:
 290          *    sp != NULL                    apply IPsec policy
 291          *    sp == NULL, error == 0        no IPsec handling needed
 292          *    sp == NULL, error == -EINVAL  discard packet w/o error
 293          *    sp == NULL, error != 0        discard packet, report error
 294          */
 295         if (sp != NULL) {
 296                 /* Loop detection, check if ipsec processing already done */
 297                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
 298                 for (mtag = m_tag_first(*m); mtag != NULL;
 299                      mtag = m_tag_next(*m, mtag)) {
 300                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 301                                 continue;
 302                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 303                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 304                                 continue;
 305                         /*
 306                          * Check if policy has an SA associated with it.
 307                          * This can happen when an SP has yet to acquire
 308                          * an SA; e.g. on first reference.  If it occurs,
 309                          * then we let ipsec4_process_packet do its thing.
 310                          */
 311                         if (sp->req->sav == NULL)
 312                                 break;
 313                         tdbi = (struct tdb_ident *)(mtag + 1);
 314                         if (tdbi->spi == sp->req->sav->spi &&
 315                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
 316                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
 317                                  sizeof (union sockaddr_union)) == 0) {
 318                                 /*
 319                                  * No IPsec processing is needed, free
 320                                  * reference to SP.
 321                                  *
 322                                  * NB: null pointer to avoid free at
 323                                  *     done: below.
 324                                  */
 325                                 KEY_FREESP(&sp), sp = NULL;
 326                                 splx(s);
 327                                 goto done;
 328                         }
 329                 }
 330
 331                 /*
 332                  * Do delayed checksums now because we send before
 333                  * this is done in the normal processing path.
 334                  */
 335                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 336                         in_delayed_cksum(*m);
 337                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 338                 }
 339 #ifdef SCTP
 340                 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP) {
 341                         sctp_delayed_cksum(*m);
 342                         (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP;
 343                 }
 344 #endif
 345                 ip->ip_len = htons(ip->ip_len);
 346                 ip->ip_off = htons(ip->ip_off);
 347
 348                 /* NB: callee frees mbuf */
 349                 *error = ipsec4_process_packet(*m, sp->req, *flags, 0);
 350                 if (*error == EJUSTRETURN) {
 351                         /*
 352                          * We had a SP with a level of 'use' and no SA. We
 353                          * will just continue to process the packet without
 354                          * IPsec processing and return without error.
 355                          */
 356                         *error = 0;
 357                         ip->ip_len = ntohs(ip->ip_len);
 358                         ip->ip_off = ntohs(ip->ip_off);
 359                         goto done;
 360                 }
 361                 /*
 362                  * Preserve KAME behaviour: ENOENT can be returned
 363                  * when an SA acquire is in progress.  Don't propagate
 364                  * this to user-level; it confuses applications.
 365                  *
 366                  * XXX this will go away when the SADB is redone.
 367                  */
 368                 if (*error == ENOENT)
 369                         *error = 0;
 370                 splx(s);
 371                 goto reinjected;
 372         } else {        /* sp == NULL */
 373                 splx(s);
 374
 375                 if (*error != 0) {
 376                         /*
 377                          * Hack: -EINVAL is used to signal that a packet
 378                          * should be silently discarded.  This is typically
 379                          * because we asked key management for an SA and
 380                          * it was delayed (e.g. kicked up to IKE).
 381                          */
 382                         if (*error == -EINVAL)
 383                                 *error = 0;
 384                         goto bad;
 385                 } else {
 386                         /* No IPsec processing for this packet. */
 387                 }
 388 #ifdef notyet
 389                 /*
 390                  * If deferred crypto processing is needed, check that
 391                  * the interface supports it.
 392                  */
 393                 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED, NULL);
 394                 if (mtag != NULL && ifp != NULL &&
 395                     ((*ifp)->if_capenable & IFCAP_IPSEC) == 0) {
 396                         /* notify IPsec to do its own crypto */
 397                         ipsp_skipcrypto_unmark((struct tdb_ident *)(mtag + 1));
 398                         *error = EHOSTUNREACH;
 399                         goto bad;
 400                 }
 401 #endif
 402         }
 403 done:
 404         if (sp != NULL)
 405                 KEY_FREESP(&sp);
 406         return 0;
 407 reinjected:
 408         if (sp != NULL)
 409                 KEY_FREESP(&sp);
 410         return -1;
 411 bad:
 412         if (sp != NULL)
 413                 KEY_FREESP(&sp);
 414         return 1;
 415 #endif /* IPSEC */
 416         return 0;
 417 }