ip6_ipsec.c

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    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  * $FreeBSD$
   30  */
   31 
   32 #include "opt_ipsec.h"
   33 
   34 #include <sys/param.h>
   35 #include <sys/systm.h>
   36 #include <sys/kernel.h>
   37 #include <sys/mac.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 
   56 #include <machine/in_cksum.h>
   57 
   58 #ifdef IPSEC
   59 #include <netipsec/ipsec.h>
   60 #include <netipsec/ipsec6.h>
   61 #include <netipsec/xform.h>
   62 #include <netipsec/key.h>
   63 #ifdef IPSEC_DEBUG
   64 #include <netipsec/key_debug.h>
   65 #else
   66 #define KEYDEBUG(lev,arg)
   67 #endif
   68 #endif /*IPSEC*/
   69 
   70 #include <netinet6/ip6_ipsec.h>
   71 
   72 extern  struct protosw inet6sw[];
   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 ip6_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 ip6_ipsec_fwd(struct mbuf *m)
  100 {
  101 #ifdef IPSEC
  102         struct m_tag *mtag;
  103         struct tdb_ident *tdbi;
  104         struct secpolicy *sp;
  105         int s, error;
  106         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
  107         s = splnet();
  108         if (mtag != NULL) {
  109                 tdbi = (struct tdb_ident *)(mtag + 1);
  110                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
  111         } else {
  112                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
  113                                            IP_FORWARDING, &error);
  114         }
  115         if (sp == NULL) {       /* NB: can happen if error */
  116                 splx(s);
  117                 /*XXX error stat???*/
  118                 DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
  119                 return 1;
  120         }
  121 
  122         /*
  123          * Check security policy against packet attributes.
  124          */
  125         error = ipsec_in_reject(sp, m);
  126         KEY_FREESP(&sp);
  127         splx(s);
  128         if (error) {
  129                 ipstat.ips_cantforward++;
  130                 return 1;
  131         }
  132 #endif /* IPSEC */
  133         return 0;
  134 }
  135 
  136 /*
  137  * Check if protocol type doesn't have a further header and do IPSEC
  138  * decryption or reject right now.  Protocols with further headers get
  139  * their IPSEC treatment within the protocol specific processing.
  140  * Called from ip_input().
  141  * 1 = drop packet, 0 = continue processing packet.
  142  */
  143 int
  144 ip6_ipsec_input(struct mbuf *m, int nxt)
  145 {
  146 #ifdef IPSEC
  147         struct m_tag *mtag;
  148         struct tdb_ident *tdbi;
  149         struct secpolicy *sp;
  150         int s, error;
  151         /*
  152          * enforce IPsec policy checking if we are seeing last header.
  153          * note that we do not visit this with protocols with pcb layer
  154          * code - like udp/tcp/raw ip.
  155          */
  156         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
  157             ipsec6_in_reject(m, NULL)) {
  158 
  159                 /*
  160                  * Check if the packet has already had IPsec processing
  161                  * done.  If so, then just pass it along.  This tag gets
  162                  * set during AH, ESP, etc. input handling, before the
  163                  * packet is returned to the ip input queue for delivery.
  164                  */
  165                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
  166                 s = splnet();
  167                 if (mtag != NULL) {
  168                         tdbi = (struct tdb_ident *)(mtag + 1);
  169                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
  170                 } else {
  171                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
  172                                                    IP_FORWARDING, &error);
  173                 }
  174                 if (sp != NULL) {
  175                         /*
  176                          * Check security policy against packet attributes.
  177                          */
  178                         error = ipsec_in_reject(sp, m);
  179                         KEY_FREESP(&sp);
  180                 } else {
  181                         /* XXX error stat??? */
  182                         error = EINVAL;
  183                         DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
  184                         return 1;
  185                 }
  186                 splx(s);
  187                 if (error)
  188                         return 1;
  189         }
  190 #endif /* IPSEC */
  191         return 0;
  192 }
  193 
  194 /*
  195  * Called from ip6_output().
  196  * 1 = drop packet, 0 = continue processing packet,
  197  * -1 = packet was reinjected and stop processing packet
  198  */
  199 
  200 int
  201 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
  202     struct ifnet **ifp, struct secpolicy **sp)
  203 {
  204 #ifdef IPSEC
  205         struct tdb_ident *tdbi;
  206         struct m_tag *mtag;
  207         /* XXX int s; */
  208         if (sp == NULL)
  209                 return 1;
  210         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
  211         if (mtag != NULL) {
  212                 tdbi = (struct tdb_ident *)(mtag + 1);
  213                 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
  214                 if (*sp == NULL)
  215                         *error = -EINVAL;       /* force silent drop */
  216                 m_tag_delete(*m, mtag);
  217         } else {
  218                 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
  219                                         error, inp);
  220         }
  221 
  222         /*
  223          * There are four return cases:
  224          *    sp != NULL                    apply IPsec policy
  225          *    sp == NULL, error == 0        no IPsec handling needed
  226          *    sp == NULL, error == -EINVAL  discard packet w/o error
  227          *    sp == NULL, error != 0        discard packet, report error
  228          */
  229         if (*sp != NULL) {
  230                 /* Loop detection, check if ipsec processing already done */
  231                 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
  232                 for (mtag = m_tag_first(*m); mtag != NULL;
  233                      mtag = m_tag_next(*m, mtag)) {
  234                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
  235                                 continue;
  236                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
  237                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
  238                                 continue;
  239                         /*
  240                          * Check if policy has an SA associated with it.
  241                          * This can happen when an SP has yet to acquire
  242                          * an SA; e.g. on first reference.  If it occurs,
  243                          * then we let ipsec4_process_packet do its thing.
  244                          */
  245                         if ((*sp)->req->sav == NULL)
  246                                 break;
  247                         tdbi = (struct tdb_ident *)(mtag + 1);
  248                         if (tdbi->spi == (*sp)->req->sav->spi &&
  249                             tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
  250                             bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
  251                                  sizeof (union sockaddr_union)) == 0) {
  252                                 /*
  253                                  * No IPsec processing is needed, free
  254                                  * reference to SP.
  255                                  *
  256                                  * NB: null pointer to avoid free at
  257                                  *     done: below.
  258                                  */
  259                                 KEY_FREESP(sp), sp = NULL;
  260                                 /* XXX splx(s); */
  261                                 goto done;
  262                         }
  263                 }
  264 
  265                 /*
  266                  * Do delayed checksums now because we send before
  267                  * this is done in the normal processing path.
  268                  */
  269                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  270                         in_delayed_cksum(*m);
  271                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  272                 }
  273 
  274                 /*
  275                  * Preserve KAME behaviour: ENOENT can be returned
  276                  * when an SA acquire is in progress.  Don't propagate
  277                  * this to user-level; it confuses applications.
  278                  *
  279                  * XXX this will go away when the SADB is redone.
  280                  */
  281                 if (*error == ENOENT)
  282                         *error = 0;
  283                 goto do_ipsec;
  284         } else {        /* sp == NULL */
  285                 if (*error != 0) {
  286                         /*
  287                          * Hack: -EINVAL is used to signal that a packet
  288                          * should be silently discarded.  This is typically
  289                          * because we asked key management for an SA and
  290                          * it was delayed (e.g. kicked up to IKE).
  291                          */
  292                         if (*error == -EINVAL)
  293                                 *error = 0;
  294                         goto bad;
  295                 } else {
  296                         /* No IPsec processing for this packet. */
  297                 }
  298         }
  299 done:
  300         if (sp != NULL)
  301                 if (*sp != NULL)
  302                         KEY_FREESP(sp);
  303         return 0;
  304 do_ipsec:
  305         return -1;
  306 bad:
  307         if (sp != NULL)
  308                 if (*sp != NULL)
  309                         KEY_FREESP(sp);
  310         return 1;
  311 #endif /* IPSEC */
  312         return 0;
  313 }
  314 
  315 /*
  316  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
  317  * Called from ip_forward().
  318  * Returns MTU suggestion for ICMP needfrag reply.
  319  */
  320 int
  321 ip6_ipsec_mtu(struct mbuf *m)
  322 {
  323         int mtu = 0;
  324         /*
  325          * If the packet is routed over IPsec tunnel, tell the
  326          * originator the tunnel MTU.
  327          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
  328          * XXX quickhack!!!
  329          */
  330         struct secpolicy *sp = NULL;
  331         int ipsecerror;
  332         int ipsechdr;
  333         struct route *ro;
  334 #ifdef IPSEC
  335         sp = ipsec_getpolicybyaddr(m,
  336                                    IPSEC_DIR_OUTBOUND,
  337                                    IP_FORWARDING,
  338                                    &ipsecerror);
  339 #endif /* IPSEC */
  340         if (sp != NULL) {
  341                 /* count IPsec header size */
  342                 ipsechdr = ipsec4_hdrsiz(m,
  343                                          IPSEC_DIR_OUTBOUND,
  344                                          NULL);
  345 
  346                 /*
  347                  * find the correct route for outer IPv4
  348                  * header, compute tunnel MTU.
  349                  */
  350                 if (sp->req != NULL &&
  351                     sp->req->sav != NULL &&
  352                     sp->req->sav->sah != NULL) {
  353                         ro = &sp->req->sav->sah->sa_route;
  354                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
  355                                 mtu =
  356                                     ro->ro_rt->rt_rmx.rmx_mtu ?
  357                                     ro->ro_rt->rt_rmx.rmx_mtu :
  358                                     ro->ro_rt->rt_ifp->if_mtu;
  359                                 mtu -= ipsechdr;
  360                         }
  361                 }
  362 #ifdef IPSEC
  363                 KEY_FREESP(&sp);
  364 #endif /* IPSEC */
  365         }
  366         return mtu;
  367 }
  368
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FreeBSD/Linux Kernel Cross Reference sys/netinet6/ip6_ipsec.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet6/ip6_ipsec.c
