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/8.4/sys/netinet6/ip6_ipsec.c 239777 2012-08-28 12:56:28Z bz $");
   32 
   33 #include "opt_inet6.h"
   34 #include "opt_ipsec.h"
   35 
   36 #include <sys/param.h>
   37 #include <sys/systm.h>
   38 #include <sys/kernel.h>
   39 #include <sys/mac.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/ip6.h>
   56 #include <netinet/in_pcb.h>
   57 #include <netinet/ip_var.h>
   58 #include <netinet/ip_options.h>
   59 
   60 #include <machine/in_cksum.h>
   61 
   62 #ifdef IPSEC
   63 #include <netipsec/ipsec.h>
   64 #include <netipsec/ipsec6.h>
   65 #include <netipsec/xform.h>
   66 #include <netipsec/key.h>
   67 #ifdef IPSEC_DEBUG
   68 #include <netipsec/key_debug.h>
   69 #else
   70 #define KEYDEBUG(lev,arg)
   71 #endif
   72 #endif /*IPSEC*/
   73 
   74 #include <netinet6/ip6_ipsec.h>
   75 #include <netinet6/ip6_var.h>
   76 
   77 extern  struct protosw inet6sw[];
   78 
   79 
   80 #ifdef INET6 
   81 #ifdef IPSEC
   82 #ifdef IPSEC_FILTERTUNNEL
   83 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 1;
   84 #else
   85 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 0;
   86 #endif
   87 #define V_ip6_ipsec6_filtertunnel       VNET(ip6_ipsec6_filtertunnel)
   88 
   89 SYSCTL_DECL(_net_inet6_ipsec6);
   90 SYSCTL_VNET_INT(_net_inet6_ipsec6, OID_AUTO,
   91         filtertunnel, CTLFLAG_RW, &VNET_NAME(ip6_ipsec6_filtertunnel),  0,
   92         "If set filter packets from an IPsec tunnel.");
   93 #endif /* IPSEC */
   94 #endif /* INET6 */
   95 
   96 /*
   97  * Check if we have to jump over firewall processing for this packet.
   98  * Called from ip6_input().
   99  * 1 = jump over firewall, 0 = packet goes through firewall.
  100  */
  101 int
  102 ip6_ipsec_filtertunnel(struct mbuf *m)
  103 {
  104 #if defined(IPSEC)
  105 
  106         /*
  107          * Bypass packet filtering for packets previously handled by IPsec.
  108          */
  109         if (!V_ip6_ipsec6_filtertunnel &&
  110             m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  111                 return 1;
  112 #endif
  113         return 0;
  114 }
  115 
  116 /*
  117  * Check if this packet has an active SA and needs to be dropped instead
  118  * of forwarded.
  119  * Called from ip6_input().
  120  * 1 = drop packet, 0 = forward packet.
  121  */
  122 int
  123 ip6_ipsec_fwd(struct mbuf *m)
  124 {
  125 #ifdef IPSEC
  126         struct m_tag *mtag;
  127         struct tdb_ident *tdbi;
  128         struct secpolicy *sp;
  129         int s, error;
  130         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
  131         s = splnet();
  132         if (mtag != NULL) {
  133                 tdbi = (struct tdb_ident *)(mtag + 1);
  134                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
  135         } else {
  136                 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
  137                                            IP_FORWARDING, &error);
  138         }
  139         if (sp == NULL) {       /* NB: can happen if error */
  140                 splx(s);
  141                 /*XXX error stat???*/
  142                 DPRINTF(("%s: no SP for forwarding\n", __func__));      /*XXX*/
  143                 return 1;
  144         }
  145 
  146         /*
  147          * Check security policy against packet attributes.
  148          */
  149         error = ipsec_in_reject(sp, m);
  150         KEY_FREESP(&sp);
  151         splx(s);
  152         if (error) {
  153                 V_ip6stat.ip6s_cantforward++;
  154                 return 1;
  155         }
  156 #endif /* IPSEC */
  157         return 0;
  158 }
  159 
  160 /*
  161  * Check if protocol type doesn't have a further header and do IPSEC
  162  * decryption or reject right now.  Protocols with further headers get
  163  * their IPSEC treatment within the protocol specific processing.
  164  * Called from ip6_input().
  165  * 1 = drop packet, 0 = continue processing packet.
  166  */
  167 int
  168 ip6_ipsec_input(struct mbuf *m, int nxt)
  169 {
  170 #ifdef IPSEC
  171         struct m_tag *mtag;
  172         struct tdb_ident *tdbi;
  173         struct secpolicy *sp;
  174         int s, error;
  175         /*
  176          * enforce IPsec policy checking if we are seeing last header.
  177          * note that we do not visit this with protocols with pcb layer
  178          * code - like udp/tcp/raw ip.
  179          */
  180         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
  181             ipsec6_in_reject(m, NULL)) {
  182 
  183                 /*
  184                  * Check if the packet has already had IPsec processing
  185                  * done.  If so, then just pass it along.  This tag gets
  186                  * set during AH, ESP, etc. input handling, before the
  187                  * packet is returned to the ip input queue for delivery.
  188                  */
  189                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
  190                 s = splnet();
  191                 if (mtag != NULL) {
  192                         tdbi = (struct tdb_ident *)(mtag + 1);
  193                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
  194                 } else {
  195                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
  196                                                    IP_FORWARDING, &error);
  197                 }
  198                 if (sp != NULL) {
  199                         /*
  200                          * Check security policy against packet attributes.
  201                          */
  202                         error = ipsec_in_reject(sp, m);
  203                         KEY_FREESP(&sp);
  204                 } else {
  205                         /* XXX error stat??? */
  206                         error = EINVAL;
  207                         DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
  208                         return 1;
  209                 }
  210                 splx(s);
  211                 if (error)
  212                         return 1;
  213         }
  214 #endif /* IPSEC */
  215         return 0;
  216 }
  217 
  218 /*
  219  * Called from ip6_output().
  220  * 1 = drop packet, 0 = continue processing packet,
  221  * -1 = packet was reinjected and stop processing packet
  222  */
  223 
  224 int
  225 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
  226     struct ifnet **ifp, struct secpolicy **sp)
  227 {
  228 #ifdef IPSEC
  229         struct tdb_ident *tdbi;
  230         struct m_tag *mtag;
  231         /* XXX int s; */
  232         if (sp == NULL)
  233                 return 1;
  234         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
  235         if (mtag != NULL) {
  236                 tdbi = (struct tdb_ident *)(mtag + 1);
  237                 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
  238                 if (*sp == NULL)
  239                         *error = -EINVAL;       /* force silent drop */
  240                 m_tag_delete(*m, mtag);
  241         } else {
  242                 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
  243                                         error, inp);
  244         }
  245 
  246         /*
  247          * There are four return cases:
  248          *    sp != NULL                    apply IPsec policy
  249          *    sp == NULL, error == 0        no IPsec handling needed
  250          *    sp == NULL, error == -EINVAL  discard packet w/o error
  251          *    sp == NULL, error != 0        discard packet, report error
  252          */
  253         if (*sp != NULL) {
  254                 /* Loop detection, check if ipsec processing already done */
  255                 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
  256                 for (mtag = m_tag_first(*m); mtag != NULL;
  257                      mtag = m_tag_next(*m, mtag)) {
  258                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
  259                                 continue;
  260                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
  261                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
  262                                 continue;
  263                         /*
  264                          * Check if policy has no SA associated with it.
  265                          * This can happen when an SP has yet to acquire
  266                          * an SA; e.g. on first reference.  If it occurs,
  267                          * then we let ipsec4_process_packet do its thing.
  268                          */
  269                         if ((*sp)->req->sav == NULL)
  270                                 break;
  271                         tdbi = (struct tdb_ident *)(mtag + 1);
  272                         if (tdbi->spi == (*sp)->req->sav->spi &&
  273                             tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
  274                             bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
  275                                  sizeof (union sockaddr_union)) == 0) {
  276                                 /*
  277                                  * No IPsec processing is needed, free
  278                                  * reference to SP.
  279                                  *
  280                                  * NB: null pointer to avoid free at
  281                                  *     done: below.
  282                                  */
  283                                 KEY_FREESP(sp), *sp = NULL;
  284                                 /* XXX splx(s); */
  285                                 goto done;
  286                         }
  287                 }
  288 
  289                 /*
  290                  * Do delayed checksums now because we send before
  291                  * this is done in the normal processing path.
  292                  */
  293                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  294                         in_delayed_cksum(*m);
  295                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  296                 }
  297 
  298                 /*
  299                  * Preserve KAME behaviour: ENOENT can be returned
  300                  * when an SA acquire is in progress.  Don't propagate
  301                  * this to user-level; it confuses applications.
  302                  *
  303                  * XXX this will go away when the SADB is redone.
  304                  */
  305                 if (*error == ENOENT)
  306                         *error = 0;
  307                 goto do_ipsec;
  308         } else {        /* sp == NULL */
  309                 if (*error != 0) {
  310                         /*
  311                          * Hack: -EINVAL is used to signal that a packet
  312                          * should be silently discarded.  This is typically
  313                          * because we asked key management for an SA and
  314                          * it was delayed (e.g. kicked up to IKE).
  315                          */
  316                         if (*error == -EINVAL)
  317                                 *error = 0;
  318                         goto bad;
  319                 } else {
  320                         /* No IPsec processing for this packet. */
  321                 }
  322         }
  323 done:
  324         return 0;
  325 do_ipsec:
  326         return -1;
  327 bad:
  328         return 1;
  329 #endif /* IPSEC */
  330         return 0;
  331 }
  332 
  333 #if 0
  334 /*
  335  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
  336  * Called from ip_forward().
  337  * Returns MTU suggestion for ICMP needfrag reply.
  338  */
  339 int
  340 ip6_ipsec_mtu(struct mbuf *m)
  341 {
  342         int mtu = 0;
  343         /*
  344          * If the packet is routed over IPsec tunnel, tell the
  345          * originator the tunnel MTU.
  346          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
  347          * XXX quickhack!!!
  348          */
  349 #ifdef IPSEC
  350         struct secpolicy *sp = NULL;
  351         int ipsecerror;
  352         int ipsechdr;
  353         struct route *ro;
  354         sp = ipsec_getpolicybyaddr(m,
  355                                    IPSEC_DIR_OUTBOUND,
  356                                    IP_FORWARDING,
  357                                    &ipsecerror);
  358         if (sp != NULL) {
  359                 /* count IPsec header size */
  360                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
  361 
  362                 /*
  363                  * find the correct route for outer IPv4
  364                  * header, compute tunnel MTU.
  365                  */
  366                 if (sp->req != NULL &&
  367                     sp->req->sav != NULL &&
  368                     sp->req->sav->sah != NULL) {
  369                         ro = &sp->req->sav->sah->route_cache.sa_route;
  370                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
  371                                 mtu =
  372                                     ro->ro_rt->rt_rmx.rmx_mtu ?
  373                                     ro->ro_rt->rt_rmx.rmx_mtu :
  374                                     ro->ro_rt->rt_ifp->if_mtu;
  375                                 mtu -= ipsechdr;
  376                         }
  377                 }
  378                 KEY_FREESP(&sp);
  379         }
  380 #endif /* IPSEC */
  381         /* XXX else case missing. */
  382         return mtu;
  383 }
  384 #endif

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