The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netinet6/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 
   30 #include <sys/cdefs.h>
   31 __FBSDID("$FreeBSD: releng/9.2/sys/netinet6/ip6_ipsec.c 250044 2013-04-29 10:52:45Z ae $");
   32 
   33 #include "opt_inet.h"
   34 #include "opt_inet6.h"
   35 #include "opt_ipsec.h"
   36 
   37 #include <sys/param.h>
   38 #include <sys/systm.h>
   39 #include <sys/kernel.h>
   40 #include <sys/mac.h>
   41 #include <sys/malloc.h>
   42 #include <sys/mbuf.h>
   43 #include <sys/protosw.h>
   44 #include <sys/socket.h>
   45 #include <sys/socketvar.h>
   46 #include <sys/sysctl.h>
   47 #include <sys/syslog.h>
   48 
   49 #include <net/if.h>
   50 #include <net/route.h>
   51 #include <net/vnet.h>
   52 
   53 #include <netinet/in.h>
   54 #include <netinet/in_systm.h>
   55 #include <netinet/in_var.h>
   56 #include <netinet/ip.h>
   57 #include <netinet/ip6.h>
   58 #include <netinet/in_pcb.h>
   59 #include <netinet/ip_var.h>
   60 #include <netinet/ip_options.h>
   61 
   62 #include <machine/in_cksum.h>
   63 
   64 #ifdef IPSEC
   65 #include <netipsec/ipsec.h>
   66 #include <netipsec/ipsec6.h>
   67 #include <netipsec/xform.h>
   68 #include <netipsec/key.h>
   69 #ifdef IPSEC_DEBUG
   70 #include <netipsec/key_debug.h>
   71 #else
   72 #define KEYDEBUG(lev,arg)
   73 #endif
   74 #endif /*IPSEC*/
   75 
   76 #include <netinet6/ip6_ipsec.h>
   77 #include <netinet6/ip6_var.h>
   78 
   79 extern  struct protosw inet6sw[];
   80 
   81 
   82 #ifdef INET6 
   83 #ifdef IPSEC
   84 #ifdef IPSEC_FILTERTUNNEL
   85 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 1;
   86 #else
   87 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 0;
   88 #endif
   89 #define V_ip6_ipsec6_filtertunnel       VNET(ip6_ipsec6_filtertunnel)
   90 
   91 SYSCTL_DECL(_net_inet6_ipsec6);
   92 SYSCTL_VNET_INT(_net_inet6_ipsec6, OID_AUTO,
   93         filtertunnel, CTLFLAG_RW, &VNET_NAME(ip6_ipsec6_filtertunnel),  0,
   94         "If set filter packets from an IPsec tunnel.");
   95 #endif /* IPSEC */
   96 #endif /* INET6 */
   97 
   98 /*
   99  * Check if we have to jump over firewall processing for this packet.
  100  * Called from ip6_input().
  101  * 1 = jump over firewall, 0 = packet goes through firewall.
  102  */
  103 int
  104 ip6_ipsec_filtertunnel(struct mbuf *m)
  105 {
  106 #if defined(IPSEC)
  107 
  108         /*
  109          * Bypass packet filtering for packets previously handled by IPsec.
  110          */
  111         if (!V_ip6_ipsec6_filtertunnel &&
  112             m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  113                 return 1;
  114 #endif
  115         return 0;
  116 }
  117 
  118 /*
  119  * Check if this packet has an active SA and needs to be dropped instead
  120  * of forwarded.
  121  * Called from ip6_input().
  122  * 1 = drop packet, 0 = forward packet.
  123  */
  124 int
  125 ip6_ipsec_fwd(struct mbuf *m)
  126 {
  127 #ifdef IPSEC
  128         struct m_tag *mtag;
  129         struct tdb_ident *tdbi;
  130         struct secpolicy *sp;
  131         int s, error;
  132         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
  133         s = splnet();
  134         if (mtag != NULL) {
  135                 tdbi = (struct tdb_ident *)(mtag + 1);
  136                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
  137         } else {
  138                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
  139                                            IP_FORWARDING, &error);
  140         }
  141         if (sp == NULL) {       /* NB: can happen if error */
  142                 splx(s);
  143                 /*XXX error stat???*/
  144                 DPRINTF(("%s: no SP for forwarding\n", __func__));      /*XXX*/
  145                 return 1;
  146         }
  147 
  148         /*
  149          * Check security policy against packet attributes.
  150          */
  151         error = ipsec_in_reject(sp, m);
  152         KEY_FREESP(&sp);
  153         splx(s);
  154         if (error) {
  155                 IP6STAT_INC(ip6s_cantforward);
  156                 return 1;
  157         }
  158 #endif /* IPSEC */
  159         return 0;
  160 }
  161 
  162 /*
  163  * Check if protocol type doesn't have a further header and do IPSEC
  164  * decryption or reject right now.  Protocols with further headers get
  165  * their IPSEC treatment within the protocol specific processing.
  166  * Called from ip6_input().
  167  * 1 = drop packet, 0 = continue processing packet.
  168  */
  169 int
  170 ip6_ipsec_input(struct mbuf *m, int nxt)
  171 {
  172 #ifdef IPSEC
  173         struct m_tag *mtag;
  174         struct tdb_ident *tdbi;
  175         struct secpolicy *sp;
  176         int s, error;
  177         /*
  178          * enforce IPsec policy checking if we are seeing last header.
  179          * note that we do not visit this with protocols with pcb layer
  180          * code - like udp/tcp/raw ip.
  181          */
  182         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
  183             ipsec6_in_reject(m, NULL)) {
  184 
  185                 /*
  186                  * Check if the packet has already had IPsec processing
  187                  * done.  If so, then just pass it along.  This tag gets
  188                  * set during AH, ESP, etc. input handling, before the
  189                  * packet is returned to the ip input queue for delivery.
  190                  */
  191                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
  192                 s = splnet();
  193                 if (mtag != NULL) {
  194                         tdbi = (struct tdb_ident *)(mtag + 1);
  195                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
  196                 } else {
  197                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
  198                                                    IP_FORWARDING, &error);
  199                 }
  200                 if (sp != NULL) {
  201                         /*
  202                          * Check security policy against packet attributes.
  203                          */
  204                         error = ipsec_in_reject(sp, m);
  205                         KEY_FREESP(&sp);
  206                 } else {
  207                         /* XXX error stat??? */
  208                         error = EINVAL;
  209                         DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
  210                         return 1;
  211                 }
  212                 splx(s);
  213                 if (error)
  214                         return 1;
  215         }
  216 #endif /* IPSEC */
  217         return 0;
  218 }
  219 
  220 /*
  221  * Called from ip6_output().
  222  * 1 = drop packet, 0 = continue processing packet,
  223  * -1 = packet was reinjected and stop processing packet
  224  */
  225 
  226 int
  227 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
  228     struct ifnet **ifp, struct secpolicy **sp)
  229 {
  230 #ifdef IPSEC
  231         struct tdb_ident *tdbi;
  232         struct m_tag *mtag;
  233         /* XXX int s; */
  234         if (sp == NULL)
  235                 return 1;
  236         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
  237         if (mtag != NULL) {
  238                 tdbi = (struct tdb_ident *)(mtag + 1);
  239                 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
  240                 if (*sp == NULL)
  241                         *error = -EINVAL;       /* force silent drop */
  242                 m_tag_delete(*m, mtag);
  243         } else {
  244                 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
  245                                         error, inp);
  246         }
  247 
  248         /*
  249          * There are four return cases:
  250          *    sp != NULL                    apply IPsec policy
  251          *    sp == NULL, error == 0        no IPsec handling needed
  252          *    sp == NULL, error == -EINVAL  discard packet w/o error
  253          *    sp == NULL, error != 0        discard packet, report error
  254          */
  255         if (*sp != NULL) {
  256                 /* Loop detection, check if ipsec processing already done */
  257                 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
  258                 for (mtag = m_tag_first(*m); mtag != NULL;
  259                      mtag = m_tag_next(*m, mtag)) {
  260                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
  261                                 continue;
  262                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
  263                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
  264                                 continue;
  265                         /*
  266                          * Check if policy has no SA associated with it.
  267                          * This can happen when an SP has yet to acquire
  268                          * an SA; e.g. on first reference.  If it occurs,
  269                          * then we let ipsec4_process_packet do its thing.
  270                          */
  271                         if ((*sp)->req->sav == NULL)
  272                                 break;
  273                         tdbi = (struct tdb_ident *)(mtag + 1);
  274                         if (tdbi->spi == (*sp)->req->sav->spi &&
  275                             tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
  276                             bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
  277                                  sizeof (union sockaddr_union)) == 0) {
  278                                 /*
  279                                  * No IPsec processing is needed, free
  280                                  * reference to SP.
  281                                  *
  282                                  * NB: null pointer to avoid free at
  283                                  *     done: below.
  284                                  */
  285                                 KEY_FREESP(sp), *sp = NULL;
  286                                 /* XXX splx(s); */
  287                                 goto done;
  288                         }
  289                 }
  290 
  291                 /*
  292                  * Do delayed checksums now because we send before
  293                  * this is done in the normal processing path.
  294                  * For IPv6 we do delayed checksums in ip6_output.c.
  295                  */
  296 #ifdef INET
  297                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  298                         ipseclog((LOG_DEBUG,
  299                             "%s: we do not support IPv4 over IPv6", __func__));
  300                         in_delayed_cksum(*m);
  301                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  302                 }
  303 #endif
  304 
  305                 /*
  306                  * Preserve KAME behaviour: ENOENT can be returned
  307                  * when an SA acquire is in progress.  Don't propagate
  308                  * this to user-level; it confuses applications.
  309                  *
  310                  * XXX this will go away when the SADB is redone.
  311                  */
  312                 if (*error == ENOENT)
  313                         *error = 0;
  314                 goto do_ipsec;
  315         } else {        /* sp == NULL */
  316                 if (*error != 0) {
  317                         /*
  318                          * Hack: -EINVAL is used to signal that a packet
  319                          * should be silently discarded.  This is typically
  320                          * because we asked key management for an SA and
  321                          * it was delayed (e.g. kicked up to IKE).
  322                          */
  323                         if (*error == -EINVAL)
  324                                 *error = 0;
  325                         goto bad;
  326                 } else {
  327                         /* No IPsec processing for this packet. */
  328                 }
  329         }
  330 done:
  331         return 0;
  332 do_ipsec:
  333         return -1;
  334 bad:
  335         return 1;
  336 #endif /* IPSEC */
  337         return 0;
  338 }
  339 
  340 #if 0
  341 /*
  342  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
  343  * Called from ip_forward().
  344  * Returns MTU suggestion for ICMP needfrag reply.
  345  */
  346 int
  347 ip6_ipsec_mtu(struct mbuf *m)
  348 {
  349         int mtu = 0;
  350         /*
  351          * If the packet is routed over IPsec tunnel, tell the
  352          * originator the tunnel MTU.
  353          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
  354          * XXX quickhack!!!
  355          */
  356 #ifdef IPSEC
  357         struct secpolicy *sp = NULL;
  358         int ipsecerror;
  359         int ipsechdr;
  360         struct route *ro;
  361         sp = ipsec_getpolicybyaddr(m,
  362                                    IPSEC_DIR_OUTBOUND,
  363                                    IP_FORWARDING,
  364                                    &ipsecerror);
  365         if (sp != NULL) {
  366                 /* count IPsec header size */
  367                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
  368 
  369                 /*
  370                  * find the correct route for outer IPv4
  371                  * header, compute tunnel MTU.
  372                  */
  373                 if (sp->req != NULL &&
  374                     sp->req->sav != NULL &&
  375                     sp->req->sav->sah != NULL) {
  376                         ro = &sp->req->sav->sah->route_cache.sa_route;
  377                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
  378                                 mtu =
  379                                     ro->ro_rt->rt_rmx.rmx_mtu ?
  380                                     ro->ro_rt->rt_rmx.rmx_mtu :
  381                                     ro->ro_rt->rt_ifp->if_mtu;
  382                                 mtu -= ipsechdr;
  383                         }
  384                 }
  385                 KEY_FREESP(&sp);
  386         }
  387 #endif /* IPSEC */
  388         /* XXX else case missing. */
  389         return mtu;
  390 }
  391 #endif

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