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/netinet/ip_encap.c

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    1 /*      $KAME: ip_encap.c,v 1.41 2001/03/15 08:35:08 itojun Exp $       */
    2 
    3 /*-
    4  * SPDX-License-Identifier: BSD-3-Clause
    5  *
    6  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    7  * Copyright (c) 2018 Andrey V. Elsukov <ae@FreeBSD.org>
    8  * All rights reserved.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. Neither the name of the project nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  */
   34 /*
   35  * My grandfather said that there's a devil inside tunnelling technology...
   36  *
   37  * We have surprisingly many protocols that want packets with IP protocol
   38  * #4 or #41.  Here's a list of protocols that want protocol #41:
   39  *      RFC1933 configured tunnel
   40  *      RFC1933 automatic tunnel
   41  *      RFC2401 IPsec tunnel
   42  *      RFC2473 IPv6 generic packet tunnelling
   43  *      RFC2529 6over4 tunnel
   44  *      mobile-ip6 (uses RFC2473)
   45  *      RFC3056 6to4 tunnel
   46  *      isatap tunnel
   47  * Here's a list of protocol that want protocol #4:
   48  *      RFC1853 IPv4-in-IPv4 tunnelling
   49  *      RFC2003 IPv4 encapsulation within IPv4
   50  *      RFC2344 reverse tunnelling for mobile-ip4
   51  *      RFC2401 IPsec tunnel
   52  * Well, what can I say.  They impose different en/decapsulation mechanism
   53  * from each other, so they need separate protocol handler.  The only one
   54  * we can easily determine by protocol # is IPsec, which always has
   55  * AH/ESP/IPComp header right after outer IP header.
   56  *
   57  * So, clearly good old protosw does not work for protocol #4 and #41.
   58  * The code will let you match protocol via src/dst address pair.
   59  */
   60 
   61 #include <sys/cdefs.h>
   62 __FBSDID("$FreeBSD: releng/12.0/sys/netinet/ip_encap.c 335924 2018-07-04 02:47:16Z mmacy $");
   63 
   64 #include "opt_inet.h"
   65 #include "opt_inet6.h"
   66 
   67 #include <sys/param.h>
   68 #include <sys/systm.h>
   69 #include <sys/kernel.h>
   70 #include <sys/lock.h>
   71 #include <sys/malloc.h>
   72 #include <sys/mutex.h>
   73 #include <sys/mbuf.h>
   74 #include <sys/errno.h>
   75 #include <sys/socket.h>
   76 
   77 #include <net/if.h>
   78 #include <net/if_var.h>
   79 
   80 #include <netinet/in.h>
   81 #include <netinet/ip_var.h>
   82 #include <netinet/ip_encap.h>
   83 
   84 #ifdef INET6
   85 #include <netinet6/ip6_var.h>
   86 #endif
   87 
   88 static MALLOC_DEFINE(M_NETADDR, "encap_export_host",
   89     "Export host address structure");
   90 
   91 struct encaptab {
   92         CK_LIST_ENTRY(encaptab) chain;
   93         int             proto;
   94         int             min_length;
   95         int             exact_match;
   96         void            *arg;
   97 
   98         encap_lookup_t  lookup;
   99         encap_check_t   check;
  100         encap_input_t   input;
  101 };
  102 
  103 CK_LIST_HEAD(encaptab_head, encaptab);
  104 #ifdef INET
  105 static struct encaptab_head ipv4_encaptab = CK_LIST_HEAD_INITIALIZER();
  106 #endif
  107 #ifdef INET6
  108 static struct encaptab_head ipv6_encaptab = CK_LIST_HEAD_INITIALIZER();
  109 #endif
  110 
  111 static struct mtx encapmtx;
  112 MTX_SYSINIT(encapmtx, &encapmtx, "encapmtx", MTX_DEF);
  113 #define ENCAP_WLOCK()           mtx_lock(&encapmtx)
  114 #define ENCAP_WUNLOCK()         mtx_unlock(&encapmtx)
  115 #define ENCAP_RLOCK()           struct epoch_tracker encap_et; epoch_enter_preempt(net_epoch_preempt, &encap_et)
  116 #define ENCAP_RUNLOCK()         epoch_exit_preempt(net_epoch_preempt, &encap_et)
  117 #define ENCAP_WAIT()            epoch_wait_preempt(net_epoch_preempt)
  118 
  119 static struct encaptab *
  120 encap_attach(struct encaptab_head *head, const struct encap_config *cfg,
  121     void *arg, int mflags)
  122 {
  123         struct encaptab *ep, *tmp;
  124 
  125         if (cfg == NULL || cfg->input == NULL ||
  126             (cfg->check == NULL && cfg->lookup == NULL) ||
  127             (cfg->lookup != NULL && cfg->exact_match != ENCAP_DRV_LOOKUP) ||
  128             (cfg->exact_match == ENCAP_DRV_LOOKUP && cfg->lookup == NULL))
  129                 return (NULL);
  130 
  131         ep = malloc(sizeof(*ep), M_NETADDR, mflags);
  132         if (ep == NULL)
  133                 return (NULL);
  134 
  135         ep->proto = cfg->proto;
  136         ep->min_length = cfg->min_length;
  137         ep->exact_match = cfg->exact_match;
  138         ep->arg = arg;
  139         ep->lookup = cfg->exact_match == ENCAP_DRV_LOOKUP ? cfg->lookup: NULL;
  140         ep->check = cfg->exact_match != ENCAP_DRV_LOOKUP ? cfg->check: NULL;
  141         ep->input = cfg->input;
  142 
  143         ENCAP_WLOCK();
  144         CK_LIST_FOREACH(tmp, head, chain) {
  145                 if (tmp->exact_match <= ep->exact_match)
  146                         break;
  147         }
  148         if (tmp == NULL)
  149                 CK_LIST_INSERT_HEAD(head, ep, chain);
  150         else
  151                 CK_LIST_INSERT_BEFORE(tmp, ep, chain);
  152         ENCAP_WUNLOCK();
  153         return (ep);
  154 }
  155 
  156 static int
  157 encap_detach(struct encaptab_head *head, const struct encaptab *cookie)
  158 {
  159         struct encaptab *ep;
  160 
  161         ENCAP_WLOCK();
  162         CK_LIST_FOREACH(ep, head, chain) {
  163                 if (ep == cookie) {
  164                         CK_LIST_REMOVE(ep, chain);
  165                         ENCAP_WUNLOCK();
  166                         ENCAP_WAIT();
  167                         free(ep, M_NETADDR);
  168                         return (0);
  169                 }
  170         }
  171         ENCAP_WUNLOCK();
  172         return (EINVAL);
  173 }
  174 
  175 static int
  176 encap_input(struct encaptab_head *head, struct mbuf *m, int off, int proto)
  177 {
  178         struct encaptab *ep, *match;
  179         void *arg;
  180         int matchprio, ret;
  181 
  182         match = NULL;
  183         matchprio = 0;
  184 
  185         ENCAP_RLOCK();
  186         CK_LIST_FOREACH(ep, head, chain) {
  187                 if (ep->proto >= 0 && ep->proto != proto)
  188                         continue;
  189                 if (ep->min_length > m->m_pkthdr.len)
  190                         continue;
  191                 if (ep->exact_match == ENCAP_DRV_LOOKUP)
  192                         ret = (*ep->lookup)(m, off, proto, &arg);
  193                 else
  194                         ret = (*ep->check)(m, off, proto, ep->arg);
  195                 if (ret <= 0)
  196                         continue;
  197                 if (ret > matchprio) {
  198                         match = ep;
  199                         if (ep->exact_match != ENCAP_DRV_LOOKUP)
  200                                 arg = ep->arg;
  201                         /*
  202                          * No need to continue the search, we got the
  203                          * exact match.
  204                          */
  205                         if (ret >= ep->exact_match)
  206                                 break;
  207                         matchprio = ret;
  208                 }
  209         }
  210 
  211         if (match != NULL) {
  212                 /* found a match, "match" has the best one */
  213                 ret = (*match->input)(m, off, proto, arg);
  214                 ENCAP_RUNLOCK();
  215                 MPASS(ret == IPPROTO_DONE);
  216                 return (IPPROTO_DONE);
  217         }
  218         ENCAP_RUNLOCK();
  219         return (0);
  220 }
  221 
  222 #ifdef INET
  223 const struct encaptab *
  224 ip_encap_attach(const struct encap_config *cfg, void *arg, int mflags)
  225 {
  226 
  227         return (encap_attach(&ipv4_encaptab, cfg, arg, mflags));
  228 }
  229 
  230 int
  231 ip_encap_detach(const struct encaptab *cookie)
  232 {
  233 
  234         return (encap_detach(&ipv4_encaptab, cookie));
  235 }
  236 
  237 int
  238 encap4_input(struct mbuf **mp, int *offp, int proto)
  239 {
  240 
  241         if (encap_input(&ipv4_encaptab, *mp, *offp, proto) != IPPROTO_DONE)
  242                 return (rip_input(mp, offp, proto));
  243         return (IPPROTO_DONE);
  244 }
  245 #endif /* INET */
  246 
  247 #ifdef INET6
  248 const struct encaptab *
  249 ip6_encap_attach(const struct encap_config *cfg, void *arg, int mflags)
  250 {
  251 
  252         return (encap_attach(&ipv6_encaptab, cfg, arg, mflags));
  253 }
  254 
  255 int
  256 ip6_encap_detach(const struct encaptab *cookie)
  257 {
  258 
  259         return (encap_detach(&ipv6_encaptab, cookie));
  260 }
  261 
  262 int
  263 encap6_input(struct mbuf **mp, int *offp, int proto)
  264 {
  265 
  266         if (encap_input(&ipv6_encaptab, *mp, *offp, proto) != IPPROTO_DONE)
  267                 return (rip6_input(mp, offp, proto));
  268         return (IPPROTO_DONE);
  269 }
  270 #endif /* INET6 */

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