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/10.2/sys/netinet6/ip6_ipsec.c 283901 2015-06-02 03:14:42Z 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/vnet.h>
   51 
   52 #include <netinet/in.h>
   53 #include <netinet/in_systm.h>
   54 #include <netinet/in_var.h>
   55 #include <netinet/ip.h>
   56 #include <netinet/ip6.h>
   57 #include <netinet/in_pcb.h>
   58 #include <netinet/ip_var.h>
   59 #include <netinet/ip_options.h>
   60 
   61 #include <machine/in_cksum.h>
   62 
   63 #ifdef IPSEC
   64 #include <netipsec/ipsec.h>
   65 #include <netipsec/ipsec6.h>
   66 #include <netipsec/xform.h>
   67 #include <netipsec/key.h>
   68 #ifdef IPSEC_DEBUG
   69 #include <netipsec/key_debug.h>
   70 #else
   71 #define KEYDEBUG(lev,arg)
   72 #endif
   73 #endif /*IPSEC*/
   74 
   75 #include <netinet6/ip6_ipsec.h>
   76 #include <netinet6/ip6_var.h>
   77 
   78 extern  struct protosw inet6sw[];
   79 
   80 
   81 #ifdef INET6 
   82 #ifdef IPSEC
   83 #ifdef IPSEC_FILTERTUNNEL
   84 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 1;
   85 #else
   86 static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 0;
   87 #endif
   88 #define V_ip6_ipsec6_filtertunnel       VNET(ip6_ipsec6_filtertunnel)
   89 
   90 SYSCTL_DECL(_net_inet6_ipsec6);
   91 SYSCTL_VNET_INT(_net_inet6_ipsec6, OID_AUTO,
   92         filtertunnel, CTLFLAG_RW, &VNET_NAME(ip6_ipsec6_filtertunnel),  0,
   93         "If set filter packets from an IPsec tunnel.");
   94 #endif /* IPSEC */
   95 #endif /* INET6 */
   96 
   97 /*
   98  * Check if we have to jump over firewall processing for this packet.
   99  * Called from ip6_input().
  100  * 1 = jump over firewall, 0 = packet goes through firewall.
  101  */
  102 int
  103 ip6_ipsec_filtertunnel(struct mbuf *m)
  104 {
  105 #ifdef IPSEC
  106 
  107         /*
  108          * Bypass packet filtering for packets previously handled by IPsec.
  109          */
  110         if (!V_ip6_ipsec6_filtertunnel &&
  111             m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
  112                 return 1;
  113 #endif
  114         return 0;
  115 }
  116 
  117 /*
  118  * Check if this packet has an active SA and needs to be dropped instead
  119  * of forwarded.
  120  * Called from ip6_input().
  121  * 1 = drop packet, 0 = forward packet.
  122  */
  123 int
  124 ip6_ipsec_fwd(struct mbuf *m)
  125 {
  126 #ifdef IPSEC
  127         struct m_tag *mtag;
  128         struct tdb_ident *tdbi;
  129         struct secpolicy *sp;
  130         int error;
  131         mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
  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                 /*XXX error stat???*/
  141                 DPRINTF(("%s: no SP for forwarding\n", __func__));      /*XXX*/
  142                 return 1;
  143         }
  144 
  145         /*
  146          * Check security policy against packet attributes.
  147          */
  148         error = ipsec_in_reject(sp, m);
  149         KEY_FREESP(&sp);
  150         if (error) {
  151                 IP6STAT_INC(ip6s_cantforward);
  152                 return 1;
  153         }
  154 #endif /* IPSEC */
  155         return 0;
  156 }
  157 
  158 /*
  159  * Check if protocol type doesn't have a further header and do IPSEC
  160  * decryption or reject right now.  Protocols with further headers get
  161  * their IPSEC treatment within the protocol specific processing.
  162  * Called from ip6_input().
  163  * 1 = drop packet, 0 = continue processing packet.
  164  */
  165 int
  166 ip6_ipsec_input(struct mbuf *m, int nxt)
  167 {
  168 #ifdef IPSEC
  169         struct m_tag *mtag;
  170         struct tdb_ident *tdbi;
  171         struct secpolicy *sp;
  172         int error;
  173         /*
  174          * enforce IPsec policy checking if we are seeing last header.
  175          * note that we do not visit this with protocols with pcb layer
  176          * code - like udp/tcp/raw ip.
  177          */
  178         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
  179             ipsec6_in_reject(m, NULL)) {
  180 
  181                 /*
  182                  * Check if the packet has already had IPsec processing
  183                  * done.  If so, then just pass it along.  This tag gets
  184                  * set during AH, ESP, etc. input handling, before the
  185                  * packet is returned to the ip input queue for delivery.
  186                  */
  187                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
  188                 if (mtag != NULL) {
  189                         tdbi = (struct tdb_ident *)(mtag + 1);
  190                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
  191                 } else {
  192                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
  193                                                    IP_FORWARDING, &error);
  194                 }
  195                 if (sp != NULL) {
  196                         /*
  197                          * Check security policy against packet attributes.
  198                          */
  199                         error = ipsec_in_reject(sp, m);
  200                         KEY_FREESP(&sp);
  201                 } else {
  202                         /* XXX error stat??? */
  203                         error = EINVAL;
  204                         DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
  205                         return 1;
  206                 }
  207                 if (error)
  208                         return 1;
  209         }
  210 #endif /* IPSEC */
  211         return 0;
  212 }
  213 
  214 /*
  215  * Called from ip6_output().
  216  * 1 = drop packet, 0 = continue processing packet,
  217  * -1 = packet was reinjected and stop processing packet
  218  */
  219 
  220 int
  221 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
  222     struct ifnet **ifp)
  223 {
  224 #ifdef IPSEC
  225         struct secpolicy *sp = NULL;
  226         struct tdb_ident *tdbi;
  227         struct m_tag *mtag;
  228         /* XXX int s; */
  229         mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
  230         if (mtag != NULL) {
  231                 tdbi = (struct tdb_ident *)(mtag + 1);
  232                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
  233                 if (sp == NULL)
  234                         *error = -EINVAL;       /* force silent drop */
  235                 m_tag_delete(*m, mtag);
  236         } else {
  237                 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
  238                                         error, inp);
  239         }
  240 
  241         /*
  242          * There are four return cases:
  243          *    sp != NULL                    apply IPsec policy
  244          *    sp == NULL, error == 0        no IPsec handling needed
  245          *    sp == NULL, error == -EINVAL  discard packet w/o error
  246          *    sp == NULL, error != 0        discard packet, report error
  247          */
  248         if (sp != NULL) {
  249                 /* Loop detection, check if ipsec processing already done */
  250                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
  251                 for (mtag = m_tag_first(*m); mtag != NULL;
  252                      mtag = m_tag_next(*m, mtag)) {
  253                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
  254                                 continue;
  255                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
  256                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
  257                                 continue;
  258                         /*
  259                          * Check if policy has no SA associated with it.
  260                          * This can happen when an SP has yet to acquire
  261                          * an SA; e.g. on first reference.  If it occurs,
  262                          * then we let ipsec4_process_packet do its thing.
  263                          */
  264                         if (sp->req->sav == NULL)
  265                                 break;
  266                         tdbi = (struct tdb_ident *)(mtag + 1);
  267                         if (tdbi->spi == sp->req->sav->spi &&
  268                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
  269                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
  270                                  sizeof (union sockaddr_union)) == 0) {
  271                                 /*
  272                                  * No IPsec processing is needed, free
  273                                  * reference to SP.
  274                                  */
  275                                 goto done;
  276                         }
  277                 }
  278 
  279                 /*
  280                  * Do delayed checksums now because we send before
  281                  * this is done in the normal processing path.
  282                  */
  283 #ifdef INET
  284                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  285                         in_delayed_cksum(*m);
  286                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  287                 }
  288 #endif
  289                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
  290                         in6_delayed_cksum(*m, (*m)->m_pkthdr.len - sizeof(struct ip6_hdr),
  291                                                         sizeof(struct ip6_hdr));
  292                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
  293                 }
  294 #ifdef SCTP
  295                 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
  296                         sctp_delayed_cksum(*m, sizeof(struct ip6_hdr));
  297                         (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
  298                 }
  299 #endif
  300 
  301                 /* NB: callee frees mbuf */
  302                 *error = ipsec6_process_packet(*m, sp->req);
  303 
  304                 if (*error == EJUSTRETURN) {
  305                         /*
  306                          * We had a SP with a level of 'use' and no SA. We
  307                          * will just continue to process the packet without
  308                          * IPsec processing.
  309                          */
  310                         *error = 0;
  311                         goto done;
  312                 }
  313 
  314                 /*
  315                  * Preserve KAME behaviour: ENOENT can be returned
  316                  * when an SA acquire is in progress.  Don't propagate
  317                  * this to user-level; it confuses applications.
  318                  *
  319                  * XXX this will go away when the SADB is redone.
  320                  */
  321                 if (*error == ENOENT)
  322                         *error = 0;
  323                 goto reinjected;
  324         } else {        /* sp == NULL */
  325                 if (*error != 0) {
  326                         /*
  327                          * Hack: -EINVAL is used to signal that a packet
  328                          * should be silently discarded.  This is typically
  329                          * because we asked key management for an SA and
  330                          * it was delayed (e.g. kicked up to IKE).
  331                          */
  332                         if (*error == -EINVAL)
  333                                 *error = 0;
  334                         goto bad;
  335                 } else {
  336                         /* No IPsec processing for this packet. */
  337                 }
  338         }
  339 done:
  340         if (sp != NULL)
  341                 KEY_FREESP(&sp);
  342         return 0;
  343 reinjected:
  344         if (sp != NULL)
  345                 KEY_FREESP(&sp);
  346         return -1;
  347 bad:
  348         if (sp != NULL)
  349                 KEY_FREESP(&sp);
  350         return 1;
  351 #endif /* IPSEC */
  352         return 0;
  353 }
  354 
  355 #if 0
  356 /*
  357  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
  358  * Called from ip_forward().
  359  * Returns MTU suggestion for ICMP needfrag reply.
  360  */
  361 int
  362 ip6_ipsec_mtu(struct mbuf *m)
  363 {
  364         int mtu = 0;
  365         /*
  366          * If the packet is routed over IPsec tunnel, tell the
  367          * originator the tunnel MTU.
  368          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
  369          * XXX quickhack!!!
  370          */
  371 #ifdef IPSEC
  372         struct secpolicy *sp = NULL;
  373         int ipsecerror;
  374         int ipsechdr;
  375         struct route *ro;
  376         sp = ipsec_getpolicybyaddr(m,
  377                                    IPSEC_DIR_OUTBOUND,
  378                                    IP_FORWARDING,
  379                                    &ipsecerror);
  380         if (sp != NULL) {
  381                 /* count IPsec header size */
  382                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
  383 
  384                 /*
  385                  * find the correct route for outer IPv4
  386                  * header, compute tunnel MTU.
  387                  */
  388                 if (sp->req != NULL &&
  389                     sp->req->sav != NULL &&
  390                     sp->req->sav->sah != NULL) {
  391                         ro = &sp->req->sav->sah->route_cache.sa_route;
  392                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
  393                                 mtu = ro->ro_rt->rt_mtu ? ro->ro_rt->rt_mtu :
  394                                     ro->ro_rt->rt_ifp->if_mtu;
  395                                 mtu -= ipsechdr;
  396                         }
  397                 }
  398                 KEY_FREESP(&sp);
  399         }
  400 #endif /* IPSEC */
  401         /* XXX else case missing. */
  402         return mtu;
  403 }
  404 #endif

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