sys/netinet6/ip6_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_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/if_var.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_INT(_net_inet6_ipsec6, OID_AUTO, filtertunnel,
  93         CTLFLAG_VNET | 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 #ifdef 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_forward().
 122  * 1 = drop packet, 0 = forward packet.
 123  */
 124 int
 125 ip6_ipsec_fwd(struct mbuf *m)
 126 {
 127
 128 #ifdef IPSEC
 129         return (ipsec6_in_reject(m, NULL));
 130 #else
 131         return (0);
 132 #endif /* !IPSEC */
 133 }
 134
 135 /*
 136  * Check if protocol type doesn't have a further header and do IPSEC
 137  * decryption or reject right now.  Protocols with further headers get
 138  * their IPSEC treatment within the protocol specific processing.
 139  * Called from ip6_input().
 140  * 1 = drop packet, 0 = continue processing packet.
 141  */
 142 int
 143 ip6_ipsec_input(struct mbuf *m, int nxt)
 144 {
 145
 146 #ifdef IPSEC
 147         /*
 148          * enforce IPsec policy checking if we are seeing last header.
 149          * note that we do not visit this with protocols with pcb layer
 150          * code - like udp/tcp/raw ip.
 151          */
 152         if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0)
 153                 return (ipsec6_in_reject(m, NULL));
 154 #endif /* IPSEC */
 155         return (0);
 156 }
 157
 158 /*
 159  * Called from ip6_output().
 160  * 1 = drop packet, 0 = continue processing packet,
 161  * -1 = packet was reinjected and stop processing packet
 162  */
 163
 164 int
 165 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *error)
 166 {
 167 #ifdef IPSEC
 168         struct secpolicy *sp;
 169
 170         /*
 171          * Check the security policy (SP) for the packet and, if
 172          * required, do IPsec-related processing.  There are two
 173          * cases here; the first time a packet is sent through
 174          * it will be untagged and handled by ipsec4_checkpolicy.
 175          * If the packet is resubmitted to ip6_output (e.g. after
 176          * AH, ESP, etc. processing), there will be a tag to bypass
 177          * the lookup and related policy checking.
 178          */
 179         if (m_tag_find(*m, PACKET_TAG_IPSEC_OUT_DONE, NULL) != NULL) {
 180                 *error = 0;
 181                 return (0);
 182         }
 183         sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, error, inp);
 184         /*
 185          * There are four return cases:
 186          *    sp != NULL                    apply IPsec policy
 187          *    sp == NULL, error == 0        no IPsec handling needed
 188          *    sp == NULL, error == -EINVAL  discard packet w/o error
 189          *    sp == NULL, error != 0        discard packet, report error
 190          */
 191         if (sp != NULL) {
 192                 /*
 193                  * Do delayed checksums now because we send before
 194                  * this is done in the normal processing path.
 195                  */
 196 #ifdef INET
 197                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 198                         in_delayed_cksum(*m);
 199                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 200                 }
 201 #endif
 202                 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
 203                         in6_delayed_cksum(*m, (*m)->m_pkthdr.len - sizeof(struct ip6_hdr),
 204                                                         sizeof(struct ip6_hdr));
 205                         (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
 206                 }
 207 #ifdef SCTP
 208                 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
 209                         sctp_delayed_cksum(*m, sizeof(struct ip6_hdr));
 210                         (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
 211                 }
 212 #endif
 213
 214                 /* NB: callee frees mbuf */
 215                 *error = ipsec6_process_packet(*m, sp->req);
 216
 217                 if (*error == EJUSTRETURN) {
 218                         /*
 219                          * We had a SP with a level of 'use' and no SA. We
 220                          * will just continue to process the packet without
 221                          * IPsec processing.
 222                          */
 223                         *error = 0;
 224                         goto done;
 225                 }
 226
 227                 /*
 228                  * Preserve KAME behaviour: ENOENT can be returned
 229                  * when an SA acquire is in progress.  Don't propagate
 230                  * this to user-level; it confuses applications.
 231                  *
 232                  * XXX this will go away when the SADB is redone.
 233                  */
 234                 if (*error == ENOENT)
 235                         *error = 0;
 236                 goto reinjected;
 237         } else {        /* sp == NULL */
 238                 if (*error != 0) {
 239                         /*
 240                          * Hack: -EINVAL is used to signal that a packet
 241                          * should be silently discarded.  This is typically
 242                          * because we asked key management for an SA and
 243                          * it was delayed (e.g. kicked up to IKE).
 244                          */
 245                         if (*error == -EINVAL)
 246                                 *error = 0;
 247                         goto bad;
 248                 }
 249                 /* No IPsec processing for this packet. */
 250         }
 251 done:
 252         if (sp != NULL)
 253                 KEY_FREESP(&sp);
 254         return 0;
 255 reinjected:
 256         if (sp != NULL)
 257                 KEY_FREESP(&sp);
 258         return -1;
 259 bad:
 260         if (sp != NULL)
 261                 KEY_FREESP(&sp);
 262         return 1;
 263 #endif /* IPSEC */
 264         return 0;
 265 }
 266
 267 #if 0
 268 /*
 269  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
 270  * Called from ip_forward().
 271  * Returns MTU suggestion for ICMP needfrag reply.
 272  */
 273 int
 274 ip6_ipsec_mtu(struct mbuf *m)
 275 {
 276         int mtu = 0;
 277         /*
 278          * If the packet is routed over IPsec tunnel, tell the
 279          * originator the tunnel MTU.
 280          *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 281          * XXX quickhack!!!
 282          */
 283 #ifdef IPSEC
 284         struct secpolicy *sp = NULL;
 285         int ipsecerror;
 286         int ipsechdr;
 287         struct route *ro;
 288         sp = ipsec_getpolicybyaddr(m,
 289                                    IPSEC_DIR_OUTBOUND,
 290                                    IP_FORWARDING,
 291                                    &ipsecerror);
 292         if (sp != NULL) {
 293                 /* count IPsec header size */
 294                 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
 295
 296                 /*
 297                  * find the correct route for outer IPv4
 298                  * header, compute tunnel MTU.
 299                  */
 300                 if (sp->req != NULL &&
 301                     sp->req->sav != NULL &&
 302                     sp->req->sav->sah != NULL) {
 303                         ro = &sp->req->sav->sah->route_cache.sa_route;
 304                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
 305                                 mtu = ro->ro_rt->rt_mtu ? ro->ro_rt->rt_mtu :
 306                                     ro->ro_rt->rt_ifp->if_mtu;
 307                                 mtu -= ipsechdr;
 308                         }
 309                 }
 310                 KEY_FREESP(&sp);
 311         }
 312 #endif /* IPSEC */
 313         /* XXX else case missing. */
 314         return mtu;
 315 }
 316 #endif