ip_encap.c

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    1 /*      $FreeBSD: src/sys/netinet/ip_encap.c,v 1.1.2.5 2003/01/23 21:06:45 sam Exp $    */
    2 /*      $KAME: ip_encap.c,v 1.41 2001/03/15 08:35:08 itojun Exp $       */
    3 
    4 /*
    5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    6  * All rights reserved.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. Neither the name of the project nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  */
   32 /*
   33  * My grandfather said that there's a devil inside tunnelling technology...
   34  *
   35  * We have surprisingly many protocols that want packets with IP protocol
   36  * #4 or #41.  Here's a list of protocols that want protocol #41:
   37  *      RFC1933 configured tunnel
   38  *      RFC1933 automatic tunnel
   39  *      RFC2401 IPsec tunnel
   40  *      RFC2473 IPv6 generic packet tunnelling
   41  *      RFC2529 6over4 tunnel
   42  *      mobile-ip6 (uses RFC2473)
   43  *      RFC3056 6to4 tunnel
   44  *      isatap tunnel
   45  * Here's a list of protocol that want protocol #4:
   46  *      RFC1853 IPv4-in-IPv4 tunnelling
   47  *      RFC2003 IPv4 encapsulation within IPv4
   48  *      RFC2344 reverse tunnelling for mobile-ip4
   49  *      RFC2401 IPsec tunnel
   50  * Well, what can I say.  They impose different en/decapsulation mechanism
   51  * from each other, so they need separate protocol handler.  The only one
   52  * we can easily determine by protocol # is IPsec, which always has
   53  * AH/ESP/IPComp header right after outer IP header.
   54  *
   55  * So, clearly good old protosw does not work for protocol #4 and #41.
   56  * The code will let you match protocol via src/dst address pair.
   57  */
   58 /* XXX is M_NETADDR correct? */
   59 
   60 #include "opt_inet.h"
   61 #include "opt_inet6.h"
   62 
   63 #include <sys/param.h>
   64 #include <sys/systm.h>
   65 #include <sys/socket.h>
   66 #include <sys/sockio.h>
   67 #include <sys/mbuf.h>
   68 #include <sys/errno.h>
   69 #include <sys/protosw.h>
   70 #include <sys/queue.h>
   71 
   72 #include <net/if.h>
   73 #include <net/route.h>
   74 
   75 #include <netinet/in.h>
   76 #include <netinet/in_systm.h>
   77 #include <netinet/ip.h>
   78 #include <netinet/ip_var.h>
   79 #include <netinet/ip_encap.h>
   80 
   81 #ifdef INET6
   82 #include <netinet/ip6.h>
   83 #include <netinet6/ip6_var.h>
   84 #include <netinet6/ip6protosw.h>
   85 #endif
   86 
   87 #include <machine/stdarg.h>
   88 
   89 #include <net/net_osdep.h>
   90 
   91 #include <sys/kernel.h>
   92 #include <sys/malloc.h>
   93 #include <sys/thread2.h>
   94 MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure");
   95 
   96 static void encap_add (struct encaptab *);
   97 static int mask_match (const struct encaptab *, const struct sockaddr *,
   98                 const struct sockaddr *);
   99 static void encap_fillarg (struct mbuf *, const struct encaptab *);
  100 
  101 #ifndef LIST_HEAD_INITIALIZER
  102 /* rely upon BSS initialization */
  103 LIST_HEAD(, encaptab) encaptab;
  104 #else
  105 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);
  106 #endif
  107 
  108 int     (*ipip_input)(struct mbuf **, int *, int); /* hook for mrouting */
  109 
  110 void
  111 encap_init(void)
  112 {
  113         static int initialized = 0;
  114 
  115         if (initialized)
  116                 return;
  117         initialized++;
  118 #if 0
  119         /*
  120          * we cannot use LIST_INIT() here, since drivers may want to call
  121          * encap_attach(), on driver attach.  encap_init() will be called
  122          * on AF_INET{,6} initialization, which happens after driver
  123          * initialization - using LIST_INIT() here can nuke encap_attach()
  124          * from drivers.
  125          */
  126         LIST_INIT(&encaptab);
  127 #endif
  128 }
  129 
  130 #ifdef INET
  131 int
  132 encap4_input(struct mbuf **mp, int *offp, int proto)
  133 {
  134         struct mbuf *m = *mp;
  135         int off = *offp;
  136         struct ip *ip;
  137         struct sockaddr_in s, d;
  138         const struct protosw *psw;
  139         struct encaptab *ep, *match;
  140         int prio, matchprio;
  141 
  142         ip = mtod(m, struct ip *);
  143         *mp = NULL;
  144 
  145         bzero(&s, sizeof s);
  146         s.sin_family = AF_INET;
  147         s.sin_len = sizeof(struct sockaddr_in);
  148         s.sin_addr = ip->ip_src;
  149         bzero(&d, sizeof d);
  150         d.sin_family = AF_INET;
  151         d.sin_len = sizeof(struct sockaddr_in);
  152         d.sin_addr = ip->ip_dst;
  153 
  154         match = NULL;
  155         matchprio = 0;
  156         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
  157                 if (ep->af != AF_INET)
  158                         continue;
  159                 if (ep->proto >= 0 && ep->proto != proto)
  160                         continue;
  161                 if (ep->func)
  162                         prio = (*ep->func)(m, off, proto, ep->arg);
  163                 else {
  164                         /*
  165                          * it's inbound traffic, we need to match in reverse
  166                          * order
  167                          */
  168                         prio = mask_match(ep,
  169                                           (struct sockaddr *)&d,
  170                                           (struct sockaddr *)&s);
  171                 }
  172 
  173                 /*
  174                  * We prioritize the matches by using bit length of the
  175                  * matches.  mask_match() and user-supplied matching function
  176                  * should return the bit length of the matches (for example,
  177                  * if both src/dst are matched for IPv4, 64 should be returned).
  178                  * 0 or negative return value means "it did not match".
  179                  *
  180                  * The question is, since we have two "mask" portion, we
  181                  * cannot really define total order between entries.
  182                  * For example, which of these should be preferred?
  183                  * mask_match() returns 48 (32 + 16) for both of them.
  184                  *      src=3ffe::/16, dst=3ffe:501::/32
  185                  *      src=3ffe:501::/32, dst=3ffe::/16
  186                  *
  187                  * We need to loop through all the possible candidates
  188                  * to get the best match - the search takes O(n) for
  189                  * n attachments (i.e. interfaces).
  190                  */
  191                 if (prio <= 0)
  192                         continue;
  193                 if (prio > matchprio) {
  194                         matchprio = prio;
  195                         match = ep;
  196                 }
  197         }
  198 
  199         if (match) {
  200                 /* found a match, "match" has the best one */
  201                 psw = match->psw;
  202                 if (psw && psw->pr_input) {
  203                         encap_fillarg(m, match);
  204                         *mp = m;
  205                         (*psw->pr_input)(mp, offp, proto);
  206                 } else {
  207                         m_freem(m);
  208                 }
  209                 return(IPPROTO_DONE);
  210         }
  211 
  212         /* for backward compatibility */
  213         if (proto == IPPROTO_IPV4 && ipip_input) {
  214                 *mp = m;
  215                 ipip_input(mp, offp, proto);
  216                 return(IPPROTO_DONE);
  217         }
  218 
  219         /* last resort: inject to raw socket */
  220         *mp = m;
  221         rip_input(mp, offp, proto);
  222         return(IPPROTO_DONE);
  223 }
  224 #endif
  225 
  226 #ifdef INET6
  227 int
  228 encap6_input(struct mbuf **mp, int *offp, int proto)
  229 {
  230         struct mbuf *m = *mp;
  231         struct ip6_hdr *ip6;
  232         struct sockaddr_in6 s, d;
  233         const struct protosw *psw;
  234         struct encaptab *ep, *match;
  235         int prio, matchprio;
  236 
  237         ip6 = mtod(m, struct ip6_hdr *);
  238 
  239         bzero(&s, sizeof s);
  240         s.sin6_family = AF_INET6;
  241         s.sin6_len = sizeof(struct sockaddr_in6);
  242         s.sin6_addr = ip6->ip6_src;
  243         bzero(&d, sizeof d);
  244         d.sin6_family = AF_INET6;
  245         d.sin6_len = sizeof(struct sockaddr_in6);
  246         d.sin6_addr = ip6->ip6_dst;
  247 
  248         match = NULL;
  249         matchprio = 0;
  250         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
  251                 if (ep->af != AF_INET6)
  252                         continue;
  253                 if (ep->proto >= 0 && ep->proto != proto)
  254                         continue;
  255                 if (ep->func)
  256                         prio = (*ep->func)(m, *offp, proto, ep->arg);
  257                 else {
  258                         /*
  259                          * it's inbound traffic, we need to match in reverse
  260                          * order
  261                          */
  262                         prio = mask_match(ep, (struct sockaddr *)&d,
  263                             (struct sockaddr *)&s);
  264                 }
  265 
  266                 /* see encap4_input() for issues here */
  267                 if (prio <= 0)
  268                         continue;
  269                 if (prio > matchprio) {
  270                         matchprio = prio;
  271                         match = ep;
  272                 }
  273         }
  274 
  275         if (match) {
  276                 /* found a match */
  277                 psw = match->psw;
  278                 if (psw && psw->pr_input) {
  279                         encap_fillarg(m, match);
  280                         return (*psw->pr_input)(mp, offp, proto);
  281                 } else {
  282                         m_freem(m);
  283                         return IPPROTO_DONE;
  284                 }
  285         }
  286 
  287         /* last resort: inject to raw socket */
  288         return rip6_input(mp, offp, proto);
  289 }
  290 #endif
  291 
  292 static void
  293 encap_add(struct encaptab *ep)
  294 {
  295 
  296         LIST_INSERT_HEAD(&encaptab, ep, chain);
  297 }
  298 
  299 /*
  300  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
  301  * length of mask (sm and dm) is assumed to be same as sp/dp.
  302  * Return value will be necessary as input (cookie) for encap_detach().
  303  */
  304 const struct encaptab *
  305 encap_attach(int af, int proto, const struct sockaddr *sp,
  306              const struct sockaddr *sm, const struct sockaddr *dp,
  307              const struct sockaddr *dm, const struct protosw *psw, void *arg)
  308 {
  309         struct encaptab *ep;
  310 
  311         crit_enter();
  312         /* sanity check on args */
  313         if (sp->sa_len > sizeof ep->src || dp->sa_len > sizeof ep->dst)
  314                 goto fail;
  315         if (sp->sa_len != dp->sa_len)
  316                 goto fail;
  317         if (af != sp->sa_family || af != dp->sa_family)
  318                 goto fail;
  319 
  320         /* check if anyone have already attached with exactly same config */
  321         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
  322                 if (ep->af != af)
  323                         continue;
  324                 if (ep->proto != proto)
  325                         continue;
  326                 if (ep->src.ss_len != sp->sa_len ||
  327                     bcmp(&ep->src, sp, sp->sa_len) != 0 ||
  328                     bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
  329                         continue;
  330                 if (ep->dst.ss_len != dp->sa_len ||
  331                     bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
  332                     bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
  333                         continue;
  334 
  335                 goto fail;
  336         }
  337 
  338         ep = kmalloc(sizeof *ep, M_NETADDR, M_INTWAIT | M_ZERO | M_NULLOK);
  339         if (ep == NULL)
  340                 goto fail;
  341 
  342         ep->af = af;
  343         ep->proto = proto;
  344         bcopy(sp, &ep->src, sp->sa_len);
  345         bcopy(sm, &ep->srcmask, sp->sa_len);
  346         bcopy(dp, &ep->dst, dp->sa_len);
  347         bcopy(dm, &ep->dstmask, dp->sa_len);
  348         ep->psw = psw;
  349         ep->arg = arg;
  350 
  351         encap_add(ep);
  352 
  353         crit_exit();
  354         return ep;
  355 
  356 fail:
  357         crit_exit();
  358         return NULL;
  359 }
  360 
  361 const struct encaptab *
  362 encap_attach_func(int af, int proto,
  363                   int (*func)(const struct mbuf *, int, int, void *),
  364                   const struct protosw *psw, void *arg)
  365 {
  366         struct encaptab *ep;
  367 
  368         crit_enter();
  369         /* sanity check on args */
  370         if (!func)
  371                 goto fail;
  372 
  373         ep = kmalloc(sizeof *ep, M_NETADDR, M_INTWAIT | M_ZERO | M_NULLOK);
  374         if (ep == NULL)
  375                 goto fail;
  376 
  377         ep->af = af;
  378         ep->proto = proto;
  379         ep->func = func;
  380         ep->psw = psw;
  381         ep->arg = arg;
  382 
  383         encap_add(ep);
  384 
  385         crit_exit();
  386         return ep;
  387 
  388 fail:
  389         crit_exit();
  390         return NULL;
  391 }
  392 
  393 int
  394 encap_detach(const struct encaptab *cookie)
  395 {
  396         const struct encaptab *ep = cookie;
  397         struct encaptab *p;
  398 
  399         for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) {
  400                 if (p == ep) {
  401                         LIST_REMOVE(p, chain);
  402                         kfree(p, M_NETADDR);    /*XXX*/
  403                         return 0;
  404                 }
  405         }
  406 
  407         return EINVAL;
  408 }
  409 
  410 static int
  411 mask_match(const struct encaptab *ep, const struct sockaddr *sp,
  412            const struct sockaddr *dp)
  413 {
  414         struct sockaddr_storage s;
  415         struct sockaddr_storage d;
  416         int i;
  417         const u_int8_t *p, *q;
  418         u_int8_t *r;
  419         int matchlen;
  420 
  421         if (sp->sa_len > sizeof s || dp->sa_len > sizeof d)
  422                 return 0;
  423         if (sp->sa_family != ep->af || dp->sa_family != ep->af)
  424                 return 0;
  425         if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
  426                 return 0;
  427 
  428         matchlen = 0;
  429 
  430         p = (const u_int8_t *)sp;
  431         q = (const u_int8_t *)&ep->srcmask;
  432         r = (u_int8_t *)&s;
  433         for (i = 0 ; i < sp->sa_len; i++) {
  434                 r[i] = p[i] & q[i];
  435                 /* XXX estimate */
  436                 matchlen += (q[i] ? 8 : 0);
  437         }
  438 
  439         p = (const u_int8_t *)dp;
  440         q = (const u_int8_t *)&ep->dstmask;
  441         r = (u_int8_t *)&d;
  442         for (i = 0 ; i < dp->sa_len; i++) {
  443                 r[i] = p[i] & q[i];
  444                 /* XXX rough estimate */
  445                 matchlen += (q[i] ? 8 : 0);
  446         }
  447 
  448         /* need to overwrite len/family portion as we don't compare them */
  449         s.ss_len = sp->sa_len;
  450         s.ss_family = sp->sa_family;
  451         d.ss_len = dp->sa_len;
  452         d.ss_family = dp->sa_family;
  453 
  454         if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
  455             bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
  456                 return matchlen;
  457         } else
  458                 return 0;
  459 }
  460 
  461 static void
  462 encap_fillarg(struct mbuf *m, const struct encaptab *ep)
  463 {
  464         struct m_tag *tag;
  465 
  466         tag = m_tag_get(PACKET_TAG_ENCAP, sizeof(void *), MB_DONTWAIT);
  467         if (tag != NULL) {
  468                 *(void **)m_tag_data(tag) = ep->arg;
  469                 m_tag_prepend(m, tag);
  470         }
  471 }
  472 
  473 void *
  474 encap_getarg(struct mbuf *m)
  475 {
  476         void *p = NULL;
  477         struct m_tag *tag;
  478 
  479         tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL);
  480         if (tag != NULL) {
  481                 p = *(void **)m_tag_data(tag);
  482                 m_tag_delete(m, tag);
  483         }
  484         return p;
  485 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet/ip_encap.c

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