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/route.h>
  49 #include <net/vnet.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 #ifdef SCTP
  60 #include <netinet/sctp_crc32.h>
  61 #endif
  62
  63 #include <machine/in_cksum.h>
  64
  65 #ifdef IPSEC
  66 #include <netipsec/ipsec.h>
  67 #include <netipsec/xform.h>
  68 #include <netipsec/key.h>
  69 #endif /*IPSEC*/
  70
  71 extern  struct protosw inetsw[];
  72
  73 #ifdef IPSEC
  74 #ifdef IPSEC_FILTERTUNNEL
  75 static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 1;
  76 #else
  77 static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 0;
  78 #endif
  79 #define V_ip4_ipsec_filtertunnel VNET(ip4_ipsec_filtertunnel)
  80
  81 SYSCTL_DECL(_net_inet_ipsec);
  82 SYSCTL_VNET_INT(_net_inet_ipsec, OID_AUTO, filtertunnel,
  83         CTLFLAG_RW, &VNET_NAME(ip4_ipsec_filtertunnel), 0,
  84         "If set filter packets from an IPsec tunnel.");
  85 #endif /* IPSEC */
  86
  87 /*
  88  * Check if we have to jump over firewall processing for this packet.
  89  * Called from ip_input().
  90  * 1 = jump over firewall, 0 = packet goes through firewall.
  91  */
  92 int
  93 ip_ipsec_filtertunnel(struct mbuf *m)
  94 {
  95 #ifdef IPSEC
  96
  97         /*
  98          * Bypass packet filtering for packets previously handled by IPsec.
  99          */
 100         if (!V_ip4_ipsec_filtertunnel &&
 101             m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
 102                 return 1;
 103 #endif
 104         return 0;
 105 }
 106
 107 /*
 108  * Check if this packet has an active SA and needs to be dropped instead
 109  * of forwarded.
 110  * Called from ip_input().
 111  * 1 = drop packet, 0 = forward packet.
 112  */
 113 int
 114 ip_ipsec_fwd(struct mbuf *m)
 115 {
 116 #ifdef IPSEC
 117         struct m_tag *mtag;
 118         struct tdb_ident *tdbi;
 119         struct secpolicy *sp;
 120         int error;
 121
 122         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 123         if (mtag != NULL) {
 124                 tdbi = (struct tdb_ident *)(mtag + 1);
 125                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 126         } else {
 127                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 128                                            IP_FORWARDING, &error);
 129         }
 130         if (sp == NULL) {       /* NB: can happen if error */
 131                 /*XXX error stat???*/
 132                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 133                 return 1;
 134         }
 135
 136         /*
 137          * Check security policy against packet attributes.
 138          */
 139         error = ipsec_in_reject(sp, m);
 140         KEY_FREESP(&sp);
 141         if (error) {
 142                 IPSTAT_INC(ips_cantforward);
 143                 return 1;
 144         }
 145 #endif /* IPSEC */
 146         return 0;
 147 }
 148
 149 /*
 150  * Check if protocol type doesn't have a further header and do IPSEC
 151  * decryption or reject right now.  Protocols with further headers get
 152  * their IPSEC treatment within the protocol specific processing.
 153  * Called from ip_input().
 154  * 1 = drop packet, 0 = continue processing packet.
 155  */
 156 int
 157 ip_ipsec_input(struct mbuf *m)
 158 {
 159 #ifdef IPSEC
 160         struct ip *ip = mtod(m, struct ip *);
 161         struct m_tag *mtag;
 162         struct tdb_ident *tdbi;
 163         struct secpolicy *sp;
 164         int error;
 165         /*
 166          * enforce IPsec policy checking if we are seeing last header.
 167          * note that we do not visit this with protocols with pcb layer
 168          * code - like udp/tcp/raw ip.
 169          */
 170         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 171                 /*
 172                  * Check if the packet has already had IPsec processing
 173                  * done.  If so, then just pass it along.  This tag gets
 174                  * set during AH, ESP, etc. input handling, before the
 175                  * packet is returned to the ip input queue for delivery.
 176                  */
 177                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 178                 if (mtag != NULL) {
 179                         tdbi = (struct tdb_ident *)(mtag + 1);
 180                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 181                 } else {
 182                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 183                                                    IP_FORWARDING, &error);
 184                 }
 185                 if (sp != NULL) {
 186                         /*
 187                          * Check security policy against packet attributes.
 188                          */
 189                         error = ipsec_in_reject(sp, m);
 190                         KEY_FREESP(&sp);
 191                 } else {
 192                         /* XXX error stat??? */
 193                         error = EINVAL;
 194                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 195                         return 1;
 196                 }
 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->route_cache.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 {
 260 #ifdef IPSEC
 261         struct secpolicy *sp = NULL;
 262         struct tdb_ident *tdbi;
 263         struct m_tag *mtag;
 264         /*
 265          * Check the security policy (SP) for the packet and, if
 266          * required, do IPsec-related processing.  There are two
 267          * cases here; the first time a packet is sent through
 268          * it will be untagged and handled by ipsec4_checkpolicy.
 269          * If the packet is resubmitted to ip_output (e.g. after
 270          * AH, ESP, etc. processing), there will be a tag to bypass
 271          * the lookup and related policy checking.
 272          */
 273         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
 274         if (mtag != NULL) {
 275                 tdbi = (struct tdb_ident *)(mtag + 1);
 276                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
 277                 if (sp == NULL)
 278                         *error = -EINVAL;       /* force silent drop */
 279                 m_tag_delete(*m, mtag);
 280         } else {
 281                 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
 282                                         error, inp);
 283         }
 284         /*
 285          * There are four return cases:
 286          *    sp != NULL                    apply IPsec policy
 287          *    sp == NULL, error == 0        no IPsec handling needed
 288          *    sp == NULL, error == -EINVAL  discard packet w/o error
 289          *    sp == NULL, error != 0        discard packet, report error
 290          */
 291         if (sp != NULL) {
 292                 /* Loop detection, check if ipsec processing already done */
 293                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
 294                 for (mtag = m_tag_first(*m); mtag != NULL;
 295                      mtag = m_tag_next(*m, mtag)) {
 296                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
 297                                 continue;
 298                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
 299                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
 300                                 continue;
 301                         /*
 302                          * Check if policy has an SA associated with it.
 303                          * This can happen when an SP has yet to acquire
 304                          * an SA; e.g. on first reference.  If it occurs,
 305                          * then we let ipsec4_process_packet do its thing.
 306                          */
 307                         if (sp->req->sav == NULL)
 308                                 break;
 309                         tdbi = (struct tdb_ident *)(mtag + 1);
 310                         if (tdbi->spi == sp->req->sav->spi &&
 311                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
 312                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
 313                                  sizeof (union sockaddr_union)) == 0) {
 314                                 /*
 315                                  * No IPsec processing is needed, free
 316                                  * reference to SP.
 317                                  *
 318                                  * NB: null pointer to avoid free at
 319                                  *     done: below.
 320                                  */
 321                                 KEY_FREESP(&sp), sp = NULL;
 322                                 goto done;
 323                         }
 324                 }
 325
 326                 /*
 327                  * Do delayed checksums now because we send before
 328                  * this is done in the normal processing path.
 329                  */
 330                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 331                         in_delayed_cksum(*m);
 332                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 333                 }
 334 #ifdef SCTP
 335                 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP) {
 336                         struct ip *ip = mtod(*m, struct ip *);
 337
 338                         sctp_delayed_cksum(*m, (uint32_t)(ip->ip_hl << 2));
 339                         (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP;
 340                 }
 341 #endif
 342
 343                 /* NB: callee frees mbuf */
 344                 *error = ipsec4_process_packet(*m, sp->req, *flags, 0);
 345                 if (*error == EJUSTRETURN) {
 346                         /*
 347                          * We had a SP with a level of 'use' and no SA. We
 348                          * will just continue to process the packet without
 349                          * IPsec processing and return without error.
 350                          */
 351                         *error = 0;
 352                         goto done;
 353                 }
 354                 /*
 355                  * Preserve KAME behaviour: ENOENT can be returned
 356                  * when an SA acquire is in progress.  Don't propagate
 357                  * this to user-level; it confuses applications.
 358                  *
 359                  * XXX this will go away when the SADB is redone.
 360                  */
 361                 if (*error == ENOENT)
 362                         *error = 0;
 363                 goto reinjected;
 364         } else {        /* sp == NULL */
 365
 366                 if (*error != 0) {
 367                         /*
 368                          * Hack: -EINVAL is used to signal that a packet
 369                          * should be silently discarded.  This is typically
 370                          * because we asked key management for an SA and
 371                          * it was delayed (e.g. kicked up to IKE).
 372                          */
 373                         if (*error == -EINVAL)
 374                                 *error = 0;
 375                         goto bad;
 376                 } else {
 377                         /* No IPsec processing for this packet. */
 378                 }
 379         }
 380 done:
 381         if (sp != NULL)
 382                 KEY_FREESP(&sp);
 383         return 0;
 384 reinjected:
 385         if (sp != NULL)
 386                 KEY_FREESP(&sp);
 387         return -1;
 388 bad:
 389         if (sp != NULL)
 390                 KEY_FREESP(&sp);
 391         return 1;
 392 #endif /* IPSEC */
 393         return 0;
 394 }