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
  59 #include "opt_inet.h"
  60 #include "opt_inet6.h"
  61
  62 #include <sys/param.h>
  63 #include <sys/systm.h>
  64 #include <sys/socket.h>
  65 #include <sys/sockio.h>
  66 #include <sys/mbuf.h>
  67 #include <sys/errno.h>
  68 #include <sys/protosw.h>
  69 #include <sys/queue.h>
  70
  71 #include <net/if.h>
  72 #include <net/route.h>
  73
  74 #include <netinet/in.h>
  75 #include <netinet/in_systm.h>
  76 #include <netinet/ip.h>
  77 #include <netinet/ip_var.h>
  78 #include <netinet/ip_encap.h>
  79
  80 #ifdef INET6
  81 #include <netinet/ip6.h>
  82 #include <netinet6/ip6_var.h>
  83 #include <netinet6/ip6protosw.h>
  84 #endif
  85
  86 #include <machine/stdarg.h>
  87
  88 #include <net/net_osdep.h>
  89
  90 #include <sys/kernel.h>
  91 #include <sys/malloc.h>
  92 #include <sys/thread2.h>
  93 MALLOC_DEFINE(M_IPENCAP, "IP Encapsulation", "IP Encapsulation");
  94
  95 static void encap_add (struct encaptab *);
  96 static int mask_match (const struct encaptab *, const struct sockaddr *,
  97                 const struct sockaddr *);
  98 static void encap_fillarg (struct mbuf *, const struct encaptab *);
  99
 100 #ifndef LIST_HEAD_INITIALIZER
 101 /* rely upon BSS initialization */
 102 LIST_HEAD(, encaptab) encaptab;
 103 #else
 104 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);
 105 #endif
 106
 107 int     (*ipip_input)(struct mbuf **, int *, int); /* hook for mrouting */
 108
 109 void
 110 encap_init(void)
 111 {
 112         static int initialized = 0;
 113
 114         if (initialized)
 115                 return;
 116         initialized++;
 117 #if 0
 118         /*
 119          * we cannot use LIST_INIT() here, since drivers may want to call
 120          * encap_attach(), on driver attach.  encap_init() will be called
 121          * on AF_INET{,6} initialization, which happens after driver
 122          * initialization - using LIST_INIT() here can nuke encap_attach()
 123          * from drivers.
 124          */
 125         LIST_INIT(&encaptab);
 126 #endif
 127 }
 128
 129 #ifdef INET
 130 int
 131 encap4_input(struct mbuf **mp, int *offp, int proto)
 132 {
 133         struct mbuf *m = *mp;
 134         int off = *offp;
 135         struct ip *ip;
 136         struct sockaddr_in s, d;
 137         const struct protosw *psw;
 138         struct encaptab *ep, *match;
 139         int prio, matchprio;
 140
 141         ip = mtod(m, struct ip *);
 142         *mp = NULL;
 143
 144         bzero(&s, sizeof s);
 145         s.sin_family = AF_INET;
 146         s.sin_len = sizeof(struct sockaddr_in);
 147         s.sin_addr = ip->ip_src;
 148         bzero(&d, sizeof d);
 149         d.sin_family = AF_INET;
 150         d.sin_len = sizeof(struct sockaddr_in);
 151         d.sin_addr = ip->ip_dst;
 152
 153         match = NULL;
 154         matchprio = 0;
 155         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 156                 if (ep->af != AF_INET)
 157                         continue;
 158                 if (ep->proto >= 0 && ep->proto != proto)
 159                         continue;
 160                 if (ep->func)
 161                         prio = (*ep->func)(m, off, proto, ep->arg);
 162                 else {
 163                         /*
 164                          * it's inbound traffic, we need to match in reverse
 165                          * order
 166                          */
 167                         prio = mask_match(ep,
 168                                           (struct sockaddr *)&d,
 169                                           (struct sockaddr *)&s);
 170                 }
 171
 172                 /*
 173                  * We prioritize the matches by using bit length of the
 174                  * matches.  mask_match() and user-supplied matching function
 175                  * should return the bit length of the matches (for example,
 176                  * if both src/dst are matched for IPv4, 64 should be returned).
 177                  * 0 or negative return value means "it did not match".
 178                  *
 179                  * The question is, since we have two "mask" portion, we
 180                  * cannot really define total order between entries.
 181                  * For example, which of these should be preferred?
 182                  * mask_match() returns 48 (32 + 16) for both of them.
 183                  *      src=3ffe::/16, dst=3ffe:501::/32
 184                  *      src=3ffe:501::/32, dst=3ffe::/16
 185                  *
 186                  * We need to loop through all the possible candidates
 187                  * to get the best match - the search takes O(n) for
 188                  * n attachments (i.e. interfaces).
 189                  */
 190                 if (prio <= 0)
 191                         continue;
 192                 if (prio > matchprio) {
 193                         matchprio = prio;
 194                         match = ep;
 195                 }
 196         }
 197
 198         if (match) {
 199                 /* found a match, "match" has the best one */
 200                 psw = match->psw;
 201                 if (psw && psw->pr_input) {
 202                         encap_fillarg(m, match);
 203                         *mp = m;
 204                         (*psw->pr_input)(mp, offp, proto);
 205                 } else {
 206                         m_freem(m);
 207                 }
 208                 return(IPPROTO_DONE);
 209         }
 210
 211         /* for backward compatibility */
 212         if (proto == IPPROTO_IPV4 && ipip_input) {
 213                 *mp = m;
 214                 ipip_input(mp, offp, proto);
 215                 return(IPPROTO_DONE);
 216         }
 217
 218         /* last resort: inject to raw socket */
 219         *mp = m;
 220         rip_input(mp, offp, proto);
 221         return(IPPROTO_DONE);
 222 }
 223 #endif
 224
 225 #ifdef INET6
 226 int
 227 encap6_input(struct mbuf **mp, int *offp, int proto)
 228 {
 229         struct mbuf *m = *mp;
 230         struct ip6_hdr *ip6;
 231         struct sockaddr_in6 s, d;
 232         const struct protosw *psw;
 233         struct encaptab *ep, *match;
 234         int prio, matchprio;
 235
 236         ip6 = mtod(m, struct ip6_hdr *);
 237
 238         bzero(&s, sizeof s);
 239         s.sin6_family = AF_INET6;
 240         s.sin6_len = sizeof(struct sockaddr_in6);
 241         s.sin6_addr = ip6->ip6_src;
 242         bzero(&d, sizeof d);
 243         d.sin6_family = AF_INET6;
 244         d.sin6_len = sizeof(struct sockaddr_in6);
 245         d.sin6_addr = ip6->ip6_dst;
 246
 247         match = NULL;
 248         matchprio = 0;
 249         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 250                 if (ep->af != AF_INET6)
 251                         continue;
 252                 if (ep->proto >= 0 && ep->proto != proto)
 253                         continue;
 254                 if (ep->func)
 255                         prio = (*ep->func)(m, *offp, proto, ep->arg);
 256                 else {
 257                         /*
 258                          * it's inbound traffic, we need to match in reverse
 259                          * order
 260                          */
 261                         prio = mask_match(ep, (struct sockaddr *)&d,
 262                             (struct sockaddr *)&s);
 263                 }
 264
 265                 /* see encap4_input() for issues here */
 266                 if (prio <= 0)
 267                         continue;
 268                 if (prio > matchprio) {
 269                         matchprio = prio;
 270                         match = ep;
 271                 }
 272         }
 273
 274         if (match) {
 275                 /* found a match */
 276                 psw = match->psw;
 277                 if (psw && psw->pr_input) {
 278                         encap_fillarg(m, match);
 279                         return (*psw->pr_input)(mp, offp, proto);
 280                 } else {
 281                         m_freem(m);
 282                         return IPPROTO_DONE;
 283                 }
 284         }
 285
 286         /* last resort: inject to raw socket */
 287         return rip6_input(mp, offp, proto);
 288 }
 289 #endif
 290
 291 static void
 292 encap_add(struct encaptab *ep)
 293 {
 294
 295         LIST_INSERT_HEAD(&encaptab, ep, chain);
 296 }
 297
 298 /*
 299  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
 300  * length of mask (sm and dm) is assumed to be same as sp/dp.
 301  * Return value will be necessary as input (cookie) for encap_detach().
 302  */
 303 const struct encaptab *
 304 encap_attach(int af, int proto, const struct sockaddr *sp,
 305              const struct sockaddr *sm, const struct sockaddr *dp,
 306              const struct sockaddr *dm, const struct protosw *psw, void *arg)
 307 {
 308         struct encaptab *ep;
 309
 310         crit_enter();
 311         /* sanity check on args */
 312         if (sp->sa_len > sizeof ep->src || dp->sa_len > sizeof ep->dst)
 313                 goto fail;
 314         if (sp->sa_len != dp->sa_len)
 315                 goto fail;
 316         if (af != sp->sa_family || af != dp->sa_family)
 317                 goto fail;
 318
 319         /* check if anyone have already attached with exactly same config */
 320         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 321                 if (ep->af != af)
 322                         continue;
 323                 if (ep->proto != proto)
 324                         continue;
 325                 if (ep->src.ss_len != sp->sa_len ||
 326                     bcmp(&ep->src, sp, sp->sa_len) != 0 ||
 327                     bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
 328                         continue;
 329                 if (ep->dst.ss_len != dp->sa_len ||
 330                     bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
 331                     bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
 332                         continue;
 333
 334                 goto fail;
 335         }
 336
 337         ep = kmalloc(sizeof *ep, M_IPENCAP, M_INTWAIT | M_ZERO | M_NULLOK);
 338         if (ep == NULL)
 339                 goto fail;
 340
 341         ep->af = af;
 342         ep->proto = proto;
 343         bcopy(sp, &ep->src, sp->sa_len);
 344         bcopy(sm, &ep->srcmask, sp->sa_len);
 345         bcopy(dp, &ep->dst, dp->sa_len);
 346         bcopy(dm, &ep->dstmask, dp->sa_len);
 347         ep->psw = psw;
 348         ep->arg = arg;
 349
 350         encap_add(ep);
 351
 352         crit_exit();
 353         return ep;
 354
 355 fail:
 356         crit_exit();
 357         return NULL;
 358 }
 359
 360 const struct encaptab *
 361 encap_attach_func(int af, int proto,
 362                   int (*func)(const struct mbuf *, int, int, void *),
 363                   const struct protosw *psw, void *arg)
 364 {
 365         struct encaptab *ep;
 366
 367         crit_enter();
 368         /* sanity check on args */
 369         if (!func)
 370                 goto fail;
 371
 372         ep = kmalloc(sizeof *ep, M_IPENCAP, M_INTWAIT | M_ZERO | M_NULLOK);
 373         if (ep == NULL)
 374                 goto fail;
 375
 376         ep->af = af;
 377         ep->proto = proto;
 378         ep->func = func;
 379         ep->psw = psw;
 380         ep->arg = arg;
 381
 382         encap_add(ep);
 383
 384         crit_exit();
 385         return ep;
 386
 387 fail:
 388         crit_exit();
 389         return NULL;
 390 }
 391
 392 int
 393 encap_detach(const struct encaptab *cookie)
 394 {
 395         const struct encaptab *ep = cookie;
 396         struct encaptab *p;
 397
 398         for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) {
 399                 if (p == ep) {
 400                         LIST_REMOVE(p, chain);
 401                         kfree(p, M_IPENCAP);    /*XXX*/
 402                         return 0;
 403                 }
 404         }
 405
 406         return EINVAL;
 407 }
 408
 409 static int
 410 mask_match(const struct encaptab *ep, const struct sockaddr *sp,
 411            const struct sockaddr *dp)
 412 {
 413         struct sockaddr_storage s;
 414         struct sockaddr_storage d;
 415         int i;
 416         const u_int8_t *p, *q;
 417         u_int8_t *r;
 418         int matchlen;
 419
 420         if (sp->sa_len > sizeof s || dp->sa_len > sizeof d)
 421                 return 0;
 422         if (sp->sa_family != ep->af || dp->sa_family != ep->af)
 423                 return 0;
 424         if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
 425                 return 0;
 426
 427         matchlen = 0;
 428
 429         p = (const u_int8_t *)sp;
 430         q = (const u_int8_t *)&ep->srcmask;
 431         r = (u_int8_t *)&s;
 432         for (i = 0 ; i < sp->sa_len; i++) {
 433                 r[i] = p[i] & q[i];
 434                 /* XXX estimate */
 435                 matchlen += (q[i] ? 8 : 0);
 436         }
 437
 438         p = (const u_int8_t *)dp;
 439         q = (const u_int8_t *)&ep->dstmask;
 440         r = (u_int8_t *)&d;
 441         for (i = 0 ; i < dp->sa_len; i++) {
 442                 r[i] = p[i] & q[i];
 443                 /* XXX rough estimate */
 444                 matchlen += (q[i] ? 8 : 0);
 445         }
 446
 447         /* need to overwrite len/family portion as we don't compare them */
 448         s.ss_len = sp->sa_len;
 449         s.ss_family = sp->sa_family;
 450         d.ss_len = dp->sa_len;
 451         d.ss_family = dp->sa_family;
 452
 453         if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
 454             bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
 455                 return matchlen;
 456         } else
 457                 return 0;
 458 }
 459
 460 static void
 461 encap_fillarg(struct mbuf *m, const struct encaptab *ep)
 462 {
 463         struct m_tag *tag;
 464
 465         tag = m_tag_get(PACKET_TAG_ENCAP, sizeof(void *), M_NOWAIT);
 466         if (tag != NULL) {
 467                 *(void **)m_tag_data(tag) = ep->arg;
 468                 m_tag_prepend(m, tag);
 469         }
 470 }
 471
 472 void *
 473 encap_getarg(struct mbuf *m)
 474 {
 475         void *p = NULL;
 476         struct m_tag *tag;
 477
 478         tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL);
 479         if (tag != NULL) {
 480                 p = *(void **)m_tag_data(tag);
 481                 m_tag_delete(m, tag);
 482         }
 483         return p;
 484 }