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/11.1/sys/netinet/ip_encap.c 293470 2016-01-09 09:34:39Z melifaro $");
   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/lock.h>
   69 #include <sys/mutex.h>
   70 #include <sys/socket.h>
   71 #include <sys/sockio.h>
   72 #include <sys/mbuf.h>
   73 #include <sys/errno.h>
   74 #include <sys/protosw.h>
   75 #include <sys/queue.h>
   76 
   77 #include <net/if.h>
   78 #include <net/route.h>
   79 
   80 #include <netinet/in.h>
   81 #include <netinet/in_systm.h>
   82 #include <netinet/ip.h>
   83 #include <netinet/ip_var.h>
   84 #include <netinet/ip_encap.h>
   85 
   86 #ifdef INET6
   87 #include <netinet/ip6.h>
   88 #include <netinet6/ip6_var.h>
   89 #endif
   90 
   91 #include <machine/stdarg.h>
   92 
   93 #include <sys/kernel.h>
   94 #include <sys/malloc.h>
   95 static MALLOC_DEFINE(M_NETADDR, "encap_export_host", "Export host address structure");
   96 
   97 static void encap_add(struct encaptab *);
   98 static int mask_match(const struct encaptab *, const struct sockaddr *,
   99                 const struct sockaddr *);
  100 static void encap_fillarg(struct mbuf *, void *);
  101 
  102 /*
  103  * All global variables in ip_encap.c are locked using encapmtx.
  104  */
  105 static struct mtx encapmtx;
  106 MTX_SYSINIT(encapmtx, &encapmtx, "encapmtx", MTX_DEF);
  107 static LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(encaptab);
  108 
  109 /*
  110  * We currently keey encap_init() for source code compatibility reasons --
  111  * it's referenced by KAME pieces in netinet6.
  112  */
  113 void
  114 encap_init(void)
  115 {
  116 }
  117 
  118 #ifdef INET
  119 int
  120 encap4_input(struct mbuf **mp, int *offp, int proto)
  121 {
  122         struct ip *ip;
  123         struct mbuf *m;
  124         struct sockaddr_in s, d;
  125         const struct protosw *psw;
  126         struct encaptab *ep, *match;
  127         void *arg;
  128         int matchprio, off, prio;
  129 
  130         m = *mp;
  131         off = *offp;
  132         ip = mtod(m, struct ip *);
  133 
  134         bzero(&s, sizeof(s));
  135         s.sin_family = AF_INET;
  136         s.sin_len = sizeof(struct sockaddr_in);
  137         s.sin_addr = ip->ip_src;
  138         bzero(&d, sizeof(d));
  139         d.sin_family = AF_INET;
  140         d.sin_len = sizeof(struct sockaddr_in);
  141         d.sin_addr = ip->ip_dst;
  142 
  143         arg = NULL;
  144         psw = NULL;
  145         match = NULL;
  146         matchprio = 0;
  147         mtx_lock(&encapmtx);
  148         LIST_FOREACH(ep, &encaptab, chain) {
  149                 if (ep->af != AF_INET)
  150                         continue;
  151                 if (ep->proto >= 0 && ep->proto != proto)
  152                         continue;
  153                 if (ep->func)
  154                         prio = (*ep->func)(m, off, proto, ep->arg);
  155                 else {
  156                         /*
  157                          * it's inbound traffic, we need to match in reverse
  158                          * order
  159                          */
  160                         prio = mask_match(ep, (struct sockaddr *)&d,
  161                             (struct sockaddr *)&s);
  162                 }
  163 
  164                 /*
  165                  * We prioritize the matches by using bit length of the
  166                  * matches.  mask_match() and user-supplied matching function
  167                  * should return the bit length of the matches (for example,
  168                  * if both src/dst are matched for IPv4, 64 should be returned).
  169                  * 0 or negative return value means "it did not match".
  170                  *
  171                  * The question is, since we have two "mask" portion, we
  172                  * cannot really define total order between entries.
  173                  * For example, which of these should be preferred?
  174                  * mask_match() returns 48 (32 + 16) for both of them.
  175                  *      src=3ffe::/16, dst=3ffe:501::/32
  176                  *      src=3ffe:501::/32, dst=3ffe::/16
  177                  *
  178                  * We need to loop through all the possible candidates
  179                  * to get the best match - the search takes O(n) for
  180                  * n attachments (i.e. interfaces).
  181                  */
  182                 if (prio <= 0)
  183                         continue;
  184                 if (prio > matchprio) {
  185                         matchprio = prio;
  186                         match = ep;
  187                 }
  188         }
  189         if (match != NULL) {
  190                 psw = match->psw;
  191                 arg = match->arg;
  192         }
  193         mtx_unlock(&encapmtx);
  194 
  195         if (match != NULL) {
  196                 /* found a match, "match" has the best one */
  197                 if (psw != NULL && psw->pr_input != NULL) {
  198                         encap_fillarg(m, arg);
  199                         (*psw->pr_input)(mp, offp, proto);
  200                 } else
  201                         m_freem(m);
  202                 return (IPPROTO_DONE);
  203         }
  204 
  205         /* last resort: inject to raw socket */
  206         return (rip_input(mp, offp, proto));
  207 }
  208 #endif
  209 
  210 #ifdef INET6
  211 int
  212 encap6_input(struct mbuf **mp, int *offp, int proto)
  213 {
  214         struct mbuf *m = *mp;
  215         struct ip6_hdr *ip6;
  216         struct sockaddr_in6 s, d;
  217         const struct protosw *psw;
  218         struct encaptab *ep, *match;
  219         void *arg;
  220         int prio, matchprio;
  221 
  222         ip6 = mtod(m, struct ip6_hdr *);
  223 
  224         bzero(&s, sizeof(s));
  225         s.sin6_family = AF_INET6;
  226         s.sin6_len = sizeof(struct sockaddr_in6);
  227         s.sin6_addr = ip6->ip6_src;
  228         bzero(&d, sizeof(d));
  229         d.sin6_family = AF_INET6;
  230         d.sin6_len = sizeof(struct sockaddr_in6);
  231         d.sin6_addr = ip6->ip6_dst;
  232 
  233         arg = NULL;
  234         psw = NULL;
  235         match = NULL;
  236         matchprio = 0;
  237         mtx_lock(&encapmtx);
  238         LIST_FOREACH(ep, &encaptab, chain) {
  239                 if (ep->af != AF_INET6)
  240                         continue;
  241                 if (ep->proto >= 0 && ep->proto != proto)
  242                         continue;
  243                 if (ep->func)
  244                         prio = (*ep->func)(m, *offp, proto, ep->arg);
  245                 else {
  246                         /*
  247                          * it's inbound traffic, we need to match in reverse
  248                          * order
  249                          */
  250                         prio = mask_match(ep, (struct sockaddr *)&d,
  251                             (struct sockaddr *)&s);
  252                 }
  253 
  254                 /* see encap4_input() for issues here */
  255                 if (prio <= 0)
  256                         continue;
  257                 if (prio > matchprio) {
  258                         matchprio = prio;
  259                         match = ep;
  260                 }
  261         }
  262         if (match != NULL) {
  263                 psw = match->psw;
  264                 arg = match->arg;
  265         }
  266         mtx_unlock(&encapmtx);
  267 
  268         if (match != NULL) {
  269                 /* found a match */
  270                 if (psw != NULL && psw->pr_input != NULL) {
  271                         encap_fillarg(m, arg);
  272                         return (*psw->pr_input)(mp, offp, proto);
  273                 } else {
  274                         m_freem(m);
  275                         return (IPPROTO_DONE);
  276                 }
  277         }
  278 
  279         /* last resort: inject to raw socket */
  280         return rip6_input(mp, offp, proto);
  281 }
  282 #endif
  283 
  284 /*lint -sem(encap_add, custodial(1)) */
  285 static void
  286 encap_add(struct encaptab *ep)
  287 {
  288 
  289         mtx_assert(&encapmtx, MA_OWNED);
  290         LIST_INSERT_HEAD(&encaptab, ep, chain);
  291 }
  292 
  293 /*
  294  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
  295  * length of mask (sm and dm) is assumed to be same as sp/dp.
  296  * Return value will be necessary as input (cookie) for encap_detach().
  297  */
  298 const struct encaptab *
  299 encap_attach(int af, int proto, const struct sockaddr *sp,
  300     const struct sockaddr *sm, const struct sockaddr *dp,
  301     const struct sockaddr *dm, const struct protosw *psw, void *arg)
  302 {
  303         struct encaptab *ep;
  304 
  305         /* sanity check on args */
  306         if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst))
  307                 return (NULL);
  308         if (sp->sa_len != dp->sa_len)
  309                 return (NULL);
  310         if (af != sp->sa_family || af != dp->sa_family)
  311                 return (NULL);
  312 
  313         /* check if anyone have already attached with exactly same config */
  314         mtx_lock(&encapmtx);
  315         LIST_FOREACH(ep, &encaptab, chain) {
  316                 if (ep->af != af)
  317                         continue;
  318                 if (ep->proto != proto)
  319                         continue;
  320                 if (ep->src.ss_len != sp->sa_len ||
  321                     bcmp(&ep->src, sp, sp->sa_len) != 0 ||
  322                     bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
  323                         continue;
  324                 if (ep->dst.ss_len != dp->sa_len ||
  325                     bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
  326                     bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
  327                         continue;
  328 
  329                 mtx_unlock(&encapmtx);
  330                 return (NULL);
  331         }
  332 
  333         ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT);  /*XXX*/
  334         if (ep == NULL) {
  335                 mtx_unlock(&encapmtx);
  336                 return (NULL);
  337         }
  338         bzero(ep, sizeof(*ep));
  339 
  340         ep->af = af;
  341         ep->proto = proto;
  342         bcopy(sp, &ep->src, sp->sa_len);
  343         bcopy(sm, &ep->srcmask, sp->sa_len);
  344         bcopy(dp, &ep->dst, dp->sa_len);
  345         bcopy(dm, &ep->dstmask, dp->sa_len);
  346         ep->psw = psw;
  347         ep->arg = arg;
  348 
  349         encap_add(ep);
  350         mtx_unlock(&encapmtx);
  351         return (ep);
  352 }
  353 
  354 const struct encaptab *
  355 encap_attach_func(int af, int proto,
  356     int (*func)(const struct mbuf *, int, int, void *),
  357     const struct protosw *psw, void *arg)
  358 {
  359         struct encaptab *ep;
  360 
  361         /* sanity check on args */
  362         if (!func)
  363                 return (NULL);
  364 
  365         ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT);  /*XXX*/
  366         if (ep == NULL)
  367                 return (NULL);
  368         bzero(ep, sizeof(*ep));
  369 
  370         ep->af = af;
  371         ep->proto = proto;
  372         ep->func = func;
  373         ep->psw = psw;
  374         ep->arg = arg;
  375 
  376         mtx_lock(&encapmtx);
  377         encap_add(ep);
  378         mtx_unlock(&encapmtx);
  379         return (ep);
  380 }
  381 
  382 int
  383 encap_detach(const struct encaptab *cookie)
  384 {
  385         const struct encaptab *ep = cookie;
  386         struct encaptab *p;
  387 
  388         mtx_lock(&encapmtx);
  389         LIST_FOREACH(p, &encaptab, chain) {
  390                 if (p == ep) {
  391                         LIST_REMOVE(p, chain);
  392                         mtx_unlock(&encapmtx);
  393                         free(p, M_NETADDR);     /*XXX*/
  394                         return 0;
  395                 }
  396         }
  397         mtx_unlock(&encapmtx);
  398 
  399         return EINVAL;
  400 }
  401 
  402 static int
  403 mask_match(const struct encaptab *ep, const struct sockaddr *sp,
  404     const struct sockaddr *dp)
  405 {
  406         struct sockaddr_storage s;
  407         struct sockaddr_storage d;
  408         int i;
  409         const u_int8_t *p, *q;
  410         u_int8_t *r;
  411         int matchlen;
  412 
  413         if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d))
  414                 return 0;
  415         if (sp->sa_family != ep->af || dp->sa_family != ep->af)
  416                 return 0;
  417         if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
  418                 return 0;
  419 
  420         matchlen = 0;
  421 
  422         p = (const u_int8_t *)sp;
  423         q = (const u_int8_t *)&ep->srcmask;
  424         r = (u_int8_t *)&s;
  425         for (i = 0 ; i < sp->sa_len; i++) {
  426                 r[i] = p[i] & q[i];
  427                 /* XXX estimate */
  428                 matchlen += (q[i] ? 8 : 0);
  429         }
  430 
  431         p = (const u_int8_t *)dp;
  432         q = (const u_int8_t *)&ep->dstmask;
  433         r = (u_int8_t *)&d;
  434         for (i = 0 ; i < dp->sa_len; i++) {
  435                 r[i] = p[i] & q[i];
  436                 /* XXX rough estimate */
  437                 matchlen += (q[i] ? 8 : 0);
  438         }
  439 
  440         /* need to overwrite len/family portion as we don't compare them */
  441         s.ss_len = sp->sa_len;
  442         s.ss_family = sp->sa_family;
  443         d.ss_len = dp->sa_len;
  444         d.ss_family = dp->sa_family;
  445 
  446         if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
  447             bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
  448                 return matchlen;
  449         } else
  450                 return 0;
  451 }
  452 
  453 static void
  454 encap_fillarg(struct mbuf *m, void *arg)
  455 {
  456         struct m_tag *tag;
  457 
  458         if (arg != NULL) {
  459                 tag = m_tag_get(PACKET_TAG_ENCAP, sizeof(void *), M_NOWAIT);
  460                 if (tag != NULL) {
  461                         *(void**)(tag+1) = arg;
  462                         m_tag_prepend(m, tag);
  463                 }
  464         }
  465 }
  466 
  467 void *
  468 encap_getarg(struct mbuf *m)
  469 {
  470         void *p = NULL;
  471         struct m_tag *tag;
  472 
  473         tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL);
  474         if (tag) {
  475                 p = *(void**)(tag+1);
  476                 m_tag_delete(m, tag);
  477         }
  478         return p;
  479 }

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