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