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("$FreeBSD$");
   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/eventhandler.h>
   70 #include <sys/kernel.h>
   71 #include <sys/lock.h>
   72 #include <sys/malloc.h>
   73 #include <sys/mutex.h>
   74 #include <sys/mbuf.h>
   75 #include <sys/errno.h>
   76 #include <sys/socket.h>
   77 
   78 #include <net/if.h>
   79 #include <net/if_var.h>
   80 
   81 #include <netinet/in.h>
   82 #include <netinet/ip_var.h>
   83 #include <netinet/ip_encap.h>
   84 
   85 #ifdef INET6
   86 #include <netinet6/ip6_var.h>
   87 #endif
   88 
   89 static MALLOC_DEFINE(M_NETADDR, "encap_export_host",
   90     "Export host address structure");
   91 
   92 struct encaptab {
   93         CK_LIST_ENTRY(encaptab) chain;
   94         int             proto;
   95         int             min_length;
   96         int             exact_match;
   97         void            *arg;
   98 
   99         encap_lookup_t  lookup;
  100         encap_check_t   check;
  101         encap_input_t   input;
  102 };
  103 
  104 struct srcaddrtab {
  105         CK_LIST_ENTRY(srcaddrtab) chain;
  106 
  107         encap_srcaddr_t srcaddr;
  108         void            *arg;
  109 };
  110 
  111 CK_LIST_HEAD(encaptab_head, encaptab);
  112 CK_LIST_HEAD(srcaddrtab_head, srcaddrtab);
  113 #ifdef INET
  114 static struct encaptab_head ipv4_encaptab = CK_LIST_HEAD_INITIALIZER();
  115 static struct srcaddrtab_head ipv4_srcaddrtab = CK_LIST_HEAD_INITIALIZER();
  116 #endif
  117 #ifdef INET6
  118 static struct encaptab_head ipv6_encaptab = CK_LIST_HEAD_INITIALIZER();
  119 static struct srcaddrtab_head ipv6_srcaddrtab = CK_LIST_HEAD_INITIALIZER();
  120 #endif
  121 
  122 static struct mtx encapmtx, srcaddrmtx;
  123 MTX_SYSINIT(encapmtx, &encapmtx, "encapmtx", MTX_DEF);
  124 MTX_SYSINIT(srcaddrmtx, &srcaddrmtx, "srcaddrmtx", MTX_DEF);
  125 #define ENCAP_WLOCK()           mtx_lock(&encapmtx)
  126 #define ENCAP_WUNLOCK()         mtx_unlock(&encapmtx)
  127 #define ENCAP_RLOCK_TRACKER     struct epoch_tracker encap_et
  128 #define ENCAP_RLOCK()           NET_EPOCH_ENTER(encap_et)
  129 #define ENCAP_RUNLOCK()         NET_EPOCH_EXIT(encap_et)
  130 #define ENCAP_WAIT()            NET_EPOCH_WAIT()
  131 
  132 #define SRCADDR_WLOCK()         mtx_lock(&srcaddrmtx)
  133 #define SRCADDR_WUNLOCK()       mtx_unlock(&srcaddrmtx)
  134 #define SRCADDR_RLOCK_TRACKER   struct epoch_tracker srcaddr_et
  135 #define SRCADDR_RLOCK()         \
  136     epoch_enter_preempt(net_epoch_preempt, &srcaddr_et)
  137 #define SRCADDR_RUNLOCK()       \
  138     epoch_exit_preempt(net_epoch_preempt, &srcaddr_et)
  139 #define SRCADDR_WAIT()          epoch_wait_preempt(net_epoch_preempt)
  140 
  141 /*
  142  * ifaddr_event_ext handler.
  143  *
  144  * Tunnelling interfaces may request the kernel to notify when
  145  * some interface addresses appears or disappears. Usually tunnelling
  146  * interface must use an address configured on the local machine as
  147  * ingress address to be able receive datagramms and do not send
  148  * spoofed packets.
  149  */
  150 static void
  151 srcaddr_change_event(void *arg __unused, struct ifnet *ifp,
  152     struct ifaddr *ifa, int event)
  153 {
  154         SRCADDR_RLOCK_TRACKER;
  155         struct srcaddrtab_head *head;
  156         struct srcaddrtab *p;
  157 
  158         /* Support for old ifaddr_event. */
  159         EVENTHANDLER_INVOKE(ifaddr_event, ifp);
  160 
  161         switch (ifa->ifa_addr->sa_family) {
  162 #ifdef INET
  163         case AF_INET:
  164                 head = &ipv4_srcaddrtab;
  165                 break;
  166 #endif
  167 #ifdef INET6
  168         case AF_INET6:
  169                 head = &ipv6_srcaddrtab;
  170                 break;
  171 #endif
  172         default:
  173                 /* ignore event */
  174                 return;
  175         }
  176 
  177         SRCADDR_RLOCK();
  178         CK_LIST_FOREACH(p, head, chain) {
  179                 (*p->srcaddr)(p->arg, ifa->ifa_addr, event);
  180         }
  181         SRCADDR_RUNLOCK();
  182 }
  183 EVENTHANDLER_DEFINE(ifaddr_event_ext, srcaddr_change_event, NULL, 0);
  184 
  185 static struct srcaddrtab *
  186 encap_register_srcaddr(struct srcaddrtab_head *head, encap_srcaddr_t func,
  187     void *arg, int mflags)
  188 {
  189         struct srcaddrtab *p, *tmp;
  190 
  191         if (func == NULL)
  192                 return (NULL);
  193         p = malloc(sizeof(*p), M_NETADDR, mflags);
  194         if (p == NULL)
  195                 return (NULL);
  196         p->srcaddr = func;
  197         p->arg = arg;
  198 
  199         SRCADDR_WLOCK();
  200         CK_LIST_FOREACH(tmp, head, chain) {
  201                 if (func == tmp->srcaddr && arg == tmp->arg)
  202                         break;
  203         }
  204         if (tmp == NULL)
  205                 CK_LIST_INSERT_HEAD(head, p, chain);
  206         SRCADDR_WUNLOCK();
  207 
  208         if (tmp != NULL) {
  209                 free(p, M_NETADDR);
  210                 p = tmp;
  211         }
  212         return (p);
  213 }
  214 
  215 static int
  216 encap_unregister_srcaddr(struct srcaddrtab_head *head,
  217     const struct srcaddrtab *cookie)
  218 {
  219         struct srcaddrtab *p;
  220 
  221         SRCADDR_WLOCK();
  222         CK_LIST_FOREACH(p, head, chain) {
  223                 if (p == cookie) {
  224                         CK_LIST_REMOVE(p, chain);
  225                         SRCADDR_WUNLOCK();
  226                         SRCADDR_WAIT();
  227                         free(p, M_NETADDR);
  228                         return (0);
  229                 }
  230         }
  231         SRCADDR_WUNLOCK();
  232         return (EINVAL);
  233 }
  234 
  235 static struct encaptab *
  236 encap_attach(struct encaptab_head *head, const struct encap_config *cfg,
  237     void *arg, int mflags)
  238 {
  239         struct encaptab *ep, *tmp;
  240 
  241         if (cfg == NULL || cfg->input == NULL ||
  242             (cfg->check == NULL && cfg->lookup == NULL) ||
  243             (cfg->lookup != NULL && cfg->exact_match != ENCAP_DRV_LOOKUP) ||
  244             (cfg->exact_match == ENCAP_DRV_LOOKUP && cfg->lookup == NULL))
  245                 return (NULL);
  246 
  247         ep = malloc(sizeof(*ep), M_NETADDR, mflags);
  248         if (ep == NULL)
  249                 return (NULL);
  250 
  251         ep->proto = cfg->proto;
  252         ep->min_length = cfg->min_length;
  253         ep->exact_match = cfg->exact_match;
  254         ep->arg = arg;
  255         ep->lookup = cfg->exact_match == ENCAP_DRV_LOOKUP ? cfg->lookup: NULL;
  256         ep->check = cfg->exact_match != ENCAP_DRV_LOOKUP ? cfg->check: NULL;
  257         ep->input = cfg->input;
  258 
  259         ENCAP_WLOCK();
  260         CK_LIST_FOREACH(tmp, head, chain) {
  261                 if (tmp->exact_match <= ep->exact_match)
  262                         break;
  263         }
  264         if (tmp == NULL)
  265                 CK_LIST_INSERT_HEAD(head, ep, chain);
  266         else
  267                 CK_LIST_INSERT_BEFORE(tmp, ep, chain);
  268         ENCAP_WUNLOCK();
  269         return (ep);
  270 }
  271 
  272 static int
  273 encap_detach(struct encaptab_head *head, const struct encaptab *cookie)
  274 {
  275         struct encaptab *ep;
  276 
  277         ENCAP_WLOCK();
  278         CK_LIST_FOREACH(ep, head, chain) {
  279                 if (ep == cookie) {
  280                         CK_LIST_REMOVE(ep, chain);
  281                         ENCAP_WUNLOCK();
  282                         ENCAP_WAIT();
  283                         free(ep, M_NETADDR);
  284                         return (0);
  285                 }
  286         }
  287         ENCAP_WUNLOCK();
  288         return (EINVAL);
  289 }
  290 
  291 static int
  292 encap_input(struct encaptab_head *head, struct mbuf *m, int off, int proto)
  293 {
  294         ENCAP_RLOCK_TRACKER;
  295         struct encaptab *ep, *match;
  296         void *arg;
  297         int matchprio, ret;
  298 
  299         match = NULL;
  300         matchprio = 0;
  301 
  302         ENCAP_RLOCK();
  303         CK_LIST_FOREACH(ep, head, chain) {
  304                 if (ep->proto >= 0 && ep->proto != proto)
  305                         continue;
  306                 if (ep->min_length > m->m_pkthdr.len)
  307                         continue;
  308                 if (ep->exact_match == ENCAP_DRV_LOOKUP)
  309                         ret = (*ep->lookup)(m, off, proto, &arg);
  310                 else
  311                         ret = (*ep->check)(m, off, proto, ep->arg);
  312                 if (ret <= 0)
  313                         continue;
  314                 if (ret > matchprio) {
  315                         match = ep;
  316                         if (ep->exact_match != ENCAP_DRV_LOOKUP)
  317                                 arg = ep->arg;
  318                         /*
  319                          * No need to continue the search, we got the
  320                          * exact match.
  321                          */
  322                         if (ret >= ep->exact_match)
  323                                 break;
  324                         matchprio = ret;
  325                 }
  326         }
  327 
  328         if (match != NULL) {
  329                 /* found a match, "match" has the best one */
  330                 ret = (*match->input)(m, off, proto, arg);
  331                 ENCAP_RUNLOCK();
  332                 MPASS(ret == IPPROTO_DONE);
  333                 return (IPPROTO_DONE);
  334         }
  335         ENCAP_RUNLOCK();
  336         return (0);
  337 }
  338 
  339 #ifdef INET
  340 const struct srcaddrtab *
  341 ip_encap_register_srcaddr(encap_srcaddr_t func, void *arg, int mflags)
  342 {
  343 
  344         return (encap_register_srcaddr(&ipv4_srcaddrtab, func, arg, mflags));
  345 }
  346 
  347 int
  348 ip_encap_unregister_srcaddr(const struct srcaddrtab *cookie)
  349 {
  350 
  351         return (encap_unregister_srcaddr(&ipv4_srcaddrtab, cookie));
  352 }
  353 
  354 const struct encaptab *
  355 ip_encap_attach(const struct encap_config *cfg, void *arg, int mflags)
  356 {
  357 
  358         return (encap_attach(&ipv4_encaptab, cfg, arg, mflags));
  359 }
  360 
  361 int
  362 ip_encap_detach(const struct encaptab *cookie)
  363 {
  364 
  365         return (encap_detach(&ipv4_encaptab, cookie));
  366 }
  367 
  368 int
  369 encap4_input(struct mbuf **mp, int *offp, int proto)
  370 {
  371 
  372         if (encap_input(&ipv4_encaptab, *mp, *offp, proto) != IPPROTO_DONE)
  373                 return (rip_input(mp, offp, proto));
  374         return (IPPROTO_DONE);
  375 }
  376 #endif /* INET */
  377 
  378 #ifdef INET6
  379 const struct srcaddrtab *
  380 ip6_encap_register_srcaddr(encap_srcaddr_t func, void *arg, int mflags)
  381 {
  382 
  383         return (encap_register_srcaddr(&ipv6_srcaddrtab, func, arg, mflags));
  384 }
  385 
  386 int
  387 ip6_encap_unregister_srcaddr(const struct srcaddrtab *cookie)
  388 {
  389 
  390         return (encap_unregister_srcaddr(&ipv6_srcaddrtab, cookie));
  391 }
  392 
  393 const struct encaptab *
  394 ip6_encap_attach(const struct encap_config *cfg, void *arg, int mflags)
  395 {
  396 
  397         return (encap_attach(&ipv6_encaptab, cfg, arg, mflags));
  398 }
  399 
  400 int
  401 ip6_encap_detach(const struct encaptab *cookie)
  402 {
  403 
  404         return (encap_detach(&ipv6_encaptab, cookie));
  405 }
  406 
  407 int
  408 encap6_input(struct mbuf **mp, int *offp, int proto)
  409 {
  410 
  411         if (encap_input(&ipv6_encaptab, *mp, *offp, proto) != IPPROTO_DONE)
  412                 return (rip6_input(mp, offp, proto));
  413         return (IPPROTO_DONE);
  414 }
  415 #endif /* INET6 */
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FreeBSD/Linux Kernel Cross Reference sys/netinet/ip_encap.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_encap.c
