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  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. Neither the name of the project nor the names of its contributors
   16  *    may be used to endorse or promote products derived from this software
   17  *    without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  */
   31 /*
   32  * My grandfather said that there's a devil inside tunnelling technology...
   33  *
   34  * We have surprisingly many protocols that want packets with IP protocol
   35  * #4 or #41.  Here's a list of protocols that want protocol #41:
   36  *      RFC1933 configured tunnel
   37  *      RFC1933 automatic tunnel
   38  *      RFC2401 IPsec tunnel
   39  *      RFC2473 IPv6 generic packet tunnelling
   40  *      RFC2529 6over4 tunnel
   41  *      mobile-ip6 (uses RFC2473)
   42  *      RFC3056 6to4 tunnel
   43  *      isatap tunnel
   44  * Here's a list of protocol that want protocol #4:
   45  *      RFC1853 IPv4-in-IPv4 tunnelling
   46  *      RFC2003 IPv4 encapsulation within IPv4
   47  *      RFC2344 reverse tunnelling for mobile-ip4
   48  *      RFC2401 IPsec tunnel
   49  * Well, what can I say.  They impose different en/decapsulation mechanism
   50  * from each other, so they need separate protocol handler.  The only one
   51  * we can easily determine by protocol # is IPsec, which always has
   52  * AH/ESP/IPComp header right after outer IP header.
   53  *
   54  * So, clearly good old protosw does not work for protocol #4 and #41.
   55  * The code will let you match protocol via src/dst address pair.
   56  */
   57 /* XXX is M_NETADDR correct? */
   58 
   59 #include <sys/cdefs.h>
   60 __FBSDID("$FreeBSD: releng/8.2/sys/netinet/ip_encap.c 203184 2010-01-30 12:11:21Z antoine $");
   61 
   62 #include "opt_mrouting.h"
   63 #include "opt_inet.h"
   64 #include "opt_inet6.h"
   65 
   66 #include <sys/param.h>
   67 #include <sys/systm.h>
   68 #include <sys/socket.h>
   69 #include <sys/sockio.h>
   70 #include <sys/mbuf.h>
   71 #include <sys/errno.h>
   72 #include <sys/protosw.h>
   73 #include <sys/queue.h>
   74 
   75 #include <net/if.h>
   76 #include <net/route.h>
   77 
   78 #include <netinet/in.h>
   79 #include <netinet/in_systm.h>
   80 #include <netinet/ip.h>
   81 #include <netinet/ip_var.h>
   82 #include <netinet/ip_encap.h>
   83 
   84 #ifdef INET6
   85 #include <netinet/ip6.h>
   86 #include <netinet6/ip6_var.h>
   87 #include <netinet6/ip6protosw.h>
   88 #endif
   89 
   90 #include <machine/stdarg.h>
   91 
   92 #include <sys/kernel.h>
   93 #include <sys/malloc.h>
   94 static MALLOC_DEFINE(M_NETADDR, "encap_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 /*
  102  * All global variables in ip_encap.c are locked using encapmtx.
  103  */
  104 static struct mtx encapmtx;
  105 MTX_SYSINIT(encapmtx, &encapmtx, "encapmtx", MTX_DEF);
  106 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(encaptab);
  107 
  108 /*
  109  * We currently keey encap_init() for source code compatibility reasons --
  110  * it's referenced by KAME pieces in netinet6.
  111  */
  112 void
  113 encap_init(void)
  114 {
  115 }
  116 
  117 #ifdef INET
  118 void
  119 encap4_input(struct mbuf *m, int off)
  120 {
  121         struct ip *ip;
  122         int proto;
  123         struct sockaddr_in s, d;
  124         const struct protosw *psw;
  125         struct encaptab *ep, *match;
  126         int prio, matchprio;
  127 
  128         ip = mtod(m, struct ip *);
  129         proto = ip->ip_p;
  130 
  131         bzero(&s, sizeof(s));
  132         s.sin_family = AF_INET;
  133         s.sin_len = sizeof(struct sockaddr_in);
  134         s.sin_addr = ip->ip_src;
  135         bzero(&d, sizeof(d));
  136         d.sin_family = AF_INET;
  137         d.sin_len = sizeof(struct sockaddr_in);
  138         d.sin_addr = ip->ip_dst;
  139 
  140         match = NULL;
  141         matchprio = 0;
  142         mtx_lock(&encapmtx);
  143         LIST_FOREACH(ep, &encaptab, chain) {
  144                 if (ep->af != AF_INET)
  145                         continue;
  146                 if (ep->proto >= 0 && ep->proto != proto)
  147                         continue;
  148                 if (ep->func)
  149                         prio = (*ep->func)(m, off, proto, ep->arg);
  150                 else {
  151                         /*
  152                          * it's inbound traffic, we need to match in reverse
  153                          * order
  154                          */
  155                         prio = mask_match(ep, (struct sockaddr *)&d,
  156                             (struct sockaddr *)&s);
  157                 }
  158 
  159                 /*
  160                  * We prioritize the matches by using bit length of the
  161                  * matches.  mask_match() and user-supplied matching function
  162                  * should return the bit length of the matches (for example,
  163                  * if both src/dst are matched for IPv4, 64 should be returned).
  164                  * 0 or negative return value means "it did not match".
  165                  *
  166                  * The question is, since we have two "mask" portion, we
  167                  * cannot really define total order between entries.
  168                  * For example, which of these should be preferred?
  169                  * mask_match() returns 48 (32 + 16) for both of them.
  170                  *      src=3ffe::/16, dst=3ffe:501::/32
  171                  *      src=3ffe:501::/32, dst=3ffe::/16
  172                  *
  173                  * We need to loop through all the possible candidates
  174                  * to get the best match - the search takes O(n) for
  175                  * n attachments (i.e. interfaces).
  176                  */
  177                 if (prio <= 0)
  178                         continue;
  179                 if (prio > matchprio) {
  180                         matchprio = prio;
  181                         match = ep;
  182                 }
  183         }
  184         mtx_unlock(&encapmtx);
  185 
  186         if (match) {
  187                 /* found a match, "match" has the best one */
  188                 psw = match->psw;
  189                 if (psw && psw->pr_input) {
  190                         encap_fillarg(m, match);
  191                         (*psw->pr_input)(m, off);
  192                 } else
  193                         m_freem(m);
  194                 return;
  195         }
  196 
  197         /* last resort: inject to raw socket */
  198         rip_input(m, off);
  199 }
  200 #endif
  201 
  202 #ifdef INET6
  203 int
  204 encap6_input(struct mbuf **mp, int *offp, int proto)
  205 {
  206         struct mbuf *m = *mp;
  207         struct ip6_hdr *ip6;
  208         struct sockaddr_in6 s, d;
  209         const struct ip6protosw *psw;
  210         struct encaptab *ep, *match;
  211         int prio, matchprio;
  212 
  213         ip6 = mtod(m, struct ip6_hdr *);
  214 
  215         bzero(&s, sizeof(s));
  216         s.sin6_family = AF_INET6;
  217         s.sin6_len = sizeof(struct sockaddr_in6);
  218         s.sin6_addr = ip6->ip6_src;
  219         bzero(&d, sizeof(d));
  220         d.sin6_family = AF_INET6;
  221         d.sin6_len = sizeof(struct sockaddr_in6);
  222         d.sin6_addr = ip6->ip6_dst;
  223 
  224         match = NULL;
  225         matchprio = 0;
  226         mtx_lock(&encapmtx);
  227         LIST_FOREACH(ep, &encaptab, chain) {
  228                 if (ep->af != AF_INET6)
  229                         continue;
  230                 if (ep->proto >= 0 && ep->proto != proto)
  231                         continue;
  232                 if (ep->func)
  233                         prio = (*ep->func)(m, *offp, proto, ep->arg);
  234                 else {
  235                         /*
  236                          * it's inbound traffic, we need to match in reverse
  237                          * order
  238                          */
  239                         prio = mask_match(ep, (struct sockaddr *)&d,
  240                             (struct sockaddr *)&s);
  241                 }
  242 
  243                 /* see encap4_input() for issues here */
  244                 if (prio <= 0)
  245                         continue;
  246                 if (prio > matchprio) {
  247                         matchprio = prio;
  248                         match = ep;
  249                 }
  250         }
  251         mtx_unlock(&encapmtx);
  252 
  253         if (match) {
  254                 /* found a match */
  255                 psw = (const struct ip6protosw *)match->psw;
  256                 if (psw && psw->pr_input) {
  257                         encap_fillarg(m, match);
  258                         return (*psw->pr_input)(mp, offp, proto);
  259                 } else {
  260                         m_freem(m);
  261                         return IPPROTO_DONE;
  262                 }
  263         }
  264 
  265         /* last resort: inject to raw socket */
  266         return rip6_input(mp, offp, proto);
  267 }
  268 #endif
  269 
  270 /*lint -sem(encap_add, custodial(1)) */
  271 static void
  272 encap_add(struct encaptab *ep)
  273 {
  274 
  275         mtx_assert(&encapmtx, MA_OWNED);
  276         LIST_INSERT_HEAD(&encaptab, ep, chain);
  277 }
  278 
  279 /*
  280  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
  281  * length of mask (sm and dm) is assumed to be same as sp/dp.
  282  * Return value will be necessary as input (cookie) for encap_detach().
  283  */
  284 const struct encaptab *
  285 encap_attach(int af, int proto, const struct sockaddr *sp,
  286     const struct sockaddr *sm, const struct sockaddr *dp,
  287     const struct sockaddr *dm, const struct protosw *psw, void *arg)
  288 {
  289         struct encaptab *ep;
  290 
  291         /* sanity check on args */
  292         if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst))
  293                 return (NULL);
  294         if (sp->sa_len != dp->sa_len)
  295                 return (NULL);
  296         if (af != sp->sa_family || af != dp->sa_family)
  297                 return (NULL);
  298 
  299         /* check if anyone have already attached with exactly same config */
  300         mtx_lock(&encapmtx);
  301         LIST_FOREACH(ep, &encaptab, chain) {
  302                 if (ep->af != af)
  303                         continue;
  304                 if (ep->proto != proto)
  305                         continue;
  306                 if (ep->src.ss_len != sp->sa_len ||
  307                     bcmp(&ep->src, sp, sp->sa_len) != 0 ||
  308                     bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
  309                         continue;
  310                 if (ep->dst.ss_len != dp->sa_len ||
  311                     bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
  312                     bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
  313                         continue;
  314 
  315                 mtx_unlock(&encapmtx);
  316                 return (NULL);
  317         }
  318 
  319         ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT);  /*XXX*/
  320         if (ep == NULL) {
  321                 mtx_unlock(&encapmtx);
  322                 return (NULL);
  323         }
  324         bzero(ep, sizeof(*ep));
  325 
  326         ep->af = af;
  327         ep->proto = proto;
  328         bcopy(sp, &ep->src, sp->sa_len);
  329         bcopy(sm, &ep->srcmask, sp->sa_len);
  330         bcopy(dp, &ep->dst, dp->sa_len);
  331         bcopy(dm, &ep->dstmask, dp->sa_len);
  332         ep->psw = psw;
  333         ep->arg = arg;
  334 
  335         encap_add(ep);
  336         mtx_unlock(&encapmtx);
  337         return (ep);
  338 }
  339 
  340 const struct encaptab *
  341 encap_attach_func(int af, int proto,
  342     int (*func)(const struct mbuf *, int, int, void *),
  343     const struct protosw *psw, void *arg)
  344 {
  345         struct encaptab *ep;
  346 
  347         /* sanity check on args */
  348         if (!func)
  349                 return (NULL);
  350 
  351         ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT);  /*XXX*/
  352         if (ep == NULL)
  353                 return (NULL);
  354         bzero(ep, sizeof(*ep));
  355 
  356         ep->af = af;
  357         ep->proto = proto;
  358         ep->func = func;
  359         ep->psw = psw;
  360         ep->arg = arg;
  361 
  362         mtx_lock(&encapmtx);
  363         encap_add(ep);
  364         mtx_unlock(&encapmtx);
  365         return (ep);
  366 }
  367 
  368 int
  369 encap_detach(const struct encaptab *cookie)
  370 {
  371         const struct encaptab *ep = cookie;
  372         struct encaptab *p;
  373 
  374         mtx_lock(&encapmtx);
  375         LIST_FOREACH(p, &encaptab, chain) {
  376                 if (p == ep) {
  377                         LIST_REMOVE(p, chain);
  378                         mtx_unlock(&encapmtx);
  379                         free(p, M_NETADDR);     /*XXX*/
  380                         return 0;
  381                 }
  382         }
  383         mtx_unlock(&encapmtx);
  384 
  385         return EINVAL;
  386 }
  387 
  388 static int
  389 mask_match(const struct encaptab *ep, const struct sockaddr *sp,
  390     const struct sockaddr *dp)
  391 {
  392         struct sockaddr_storage s;
  393         struct sockaddr_storage d;
  394         int i;
  395         const u_int8_t *p, *q;
  396         u_int8_t *r;
  397         int matchlen;
  398 
  399         if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d))
  400                 return 0;
  401         if (sp->sa_family != ep->af || dp->sa_family != ep->af)
  402                 return 0;
  403         if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
  404                 return 0;
  405 
  406         matchlen = 0;
  407 
  408         p = (const u_int8_t *)sp;
  409         q = (const u_int8_t *)&ep->srcmask;
  410         r = (u_int8_t *)&s;
  411         for (i = 0 ; i < sp->sa_len; i++) {
  412                 r[i] = p[i] & q[i];
  413                 /* XXX estimate */
  414                 matchlen += (q[i] ? 8 : 0);
  415         }
  416 
  417         p = (const u_int8_t *)dp;
  418         q = (const u_int8_t *)&ep->dstmask;
  419         r = (u_int8_t *)&d;
  420         for (i = 0 ; i < dp->sa_len; i++) {
  421                 r[i] = p[i] & q[i];
  422                 /* XXX rough estimate */
  423                 matchlen += (q[i] ? 8 : 0);
  424         }
  425 
  426         /* need to overwrite len/family portion as we don't compare them */
  427         s.ss_len = sp->sa_len;
  428         s.ss_family = sp->sa_family;
  429         d.ss_len = dp->sa_len;
  430         d.ss_family = dp->sa_family;
  431 
  432         if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
  433             bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
  434                 return matchlen;
  435         } else
  436                 return 0;
  437 }
  438 
  439 static void
  440 encap_fillarg(struct mbuf *m, const struct encaptab *ep)
  441 {
  442         struct m_tag *tag;
  443 
  444         tag = m_tag_get(PACKET_TAG_ENCAP, sizeof (void*), M_NOWAIT);
  445         if (tag) {
  446                 *(void**)(tag+1) = ep->arg;
  447                 m_tag_prepend(m, tag);
  448         }
  449 }
  450 
  451 void *
  452 encap_getarg(struct mbuf *m)
  453 {
  454         void *p = NULL;
  455         struct m_tag *tag;
  456 
  457         tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL);
  458         if (tag) {
  459                 p = *(void**)(tag+1);
  460                 m_tag_delete(m, tag);
  461         }
  462         return p;
  463 }

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