sys/netinet/ip_encap.c

   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("$FreeBSD$");
  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 }