sys/netinet/ip_encap.c

   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 *), M_NOWAIT);
 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 }