1 /* $FreeBSD$ */ 2 /* $KAME: ip_encap.c,v 1.36 2000/06/17 20:34:24 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 * 6to4 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 "opt_mrouting.h" 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 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 #ifdef MROUTING 80 #include <netinet/ip_mroute.h> 81 #endif /* MROUTING */ 82 #include <netinet/ipprotosw.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 <net/net_osdep.h> 93 94 #include <sys/kernel.h> 95 #include <sys/malloc.h> 96 MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure"); 97 98 static void encap_add __P((struct encaptab *)); 99 static int mask_match __P((const struct encaptab *, const struct sockaddr *, 100 const struct sockaddr *)); 101 static void encap_fillarg __P((struct mbuf *, const struct encaptab *)); 102 103 /* rely upon BSS initialization */ 104 LIST_HEAD(, encaptab) encaptab; 105 106 void 107 encap_init() 108 { 109 #if 0 110 /* 111 * we cannot use LIST_INIT() here, since drivers may want to call 112 * encap_attach(), on driver attach. encap_init() will be called 113 * on AF_INET{,6} initialization, which happens after driver 114 * initialization - using LIST_INIT() here can nuke encap_attach() 115 * from drivers. 116 */ 117 LIST_INIT(&encaptab); 118 #endif 119 } 120 121 void 122 #if __STDC__ 123 encap4_input(struct mbuf *m, ...) 124 #else 125 encap4_input(m, va_alist) 126 struct mbuf *m; 127 va_dcl 128 #endif 129 { 130 int off, proto; 131 struct ip *ip; 132 struct sockaddr_in s, d; 133 const struct ipprotosw *psw; 134 struct encaptab *ep, *match; 135 va_list ap; 136 int prio, matchprio; 137 138 va_start(ap, m); 139 off = va_arg(ap, int); 140 proto = va_arg(ap, int); 141 va_end(ap); 142 143 ip = mtod(m, struct ip *); 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, (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 = (const struct ipprotosw *)match->psw; 201 if (psw && psw->pr_input) { 202 encap_fillarg(m, match); 203 (*psw->pr_input)(m, off, proto); 204 } else 205 m_freem(m); 206 return; 207 } 208 209 /* for backward compatibility */ 210 # ifdef MROUTING 211 # define COMPATFUNC ipip_input 212 # endif /*MROUTING*/ 213 214 #ifdef COMPATFUNC 215 if (proto == IPPROTO_IPV4) { 216 COMPATFUNC(m, off, proto); 217 return; 218 } 219 #endif 220 221 /* last resort: inject to raw socket */ 222 rip_input(m, off, proto); 223 } 224 225 #ifdef INET6 226 int 227 encap6_input(mp, offp, proto) 228 struct mbuf **mp; 229 int *offp; 230 int proto; 231 { 232 struct mbuf *m = *mp; 233 struct ip6_hdr *ip6; 234 struct sockaddr_in6 s, d; 235 const struct ip6protosw *psw; 236 struct encaptab *ep, *match; 237 int prio, matchprio; 238 239 ip6 = mtod(m, struct ip6_hdr *); 240 241 bzero(&s, sizeof(s)); 242 s.sin6_family = AF_INET6; 243 s.sin6_len = sizeof(struct sockaddr_in6); 244 s.sin6_addr = ip6->ip6_src; 245 bzero(&d, sizeof(d)); 246 d.sin6_family = AF_INET6; 247 d.sin6_len = sizeof(struct sockaddr_in6); 248 d.sin6_addr = ip6->ip6_dst; 249 250 match = NULL; 251 matchprio = 0; 252 for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) { 253 if (ep->af != AF_INET6) 254 continue; 255 if (ep->proto >= 0 && ep->proto != proto) 256 continue; 257 if (ep->func) 258 prio = (*ep->func)(m, *offp, proto, ep->arg); 259 else { 260 /* 261 * it's inbound traffic, we need to match in reverse 262 * order 263 */ 264 prio = mask_match(ep, (struct sockaddr *)&d, 265 (struct sockaddr *)&s); 266 } 267 268 /* see encap4_input() for issues here */ 269 if (prio <= 0) 270 continue; 271 if (prio > matchprio) { 272 matchprio = prio; 273 match = ep; 274 } 275 } 276 277 if (match) { 278 /* found a match */ 279 psw = (const struct ip6protosw *)match->psw; 280 if (psw && psw->pr_input) { 281 encap_fillarg(m, match); 282 return (*psw->pr_input)(mp, offp, proto); 283 } else { 284 m_freem(m); 285 return IPPROTO_DONE; 286 } 287 } 288 289 /* last resort: inject to raw socket */ 290 return rip6_input(mp, offp, proto); 291 } 292 #endif 293 294 static void 295 encap_add(ep) 296 struct encaptab *ep; 297 { 298 299 LIST_INSERT_HEAD(&encaptab, ep, chain); 300 } 301 302 /* 303 * sp (src ptr) is always my side, and dp (dst ptr) is always remote side. 304 * length of mask (sm and dm) is assumed to be same as sp/dp. 305 * Return value will be necessary as input (cookie) for encap_detach(). 306 */ 307 const struct encaptab * 308 encap_attach(af, proto, sp, sm, dp, dm, psw, arg) 309 int af; 310 int proto; 311 const struct sockaddr *sp, *sm; 312 const struct sockaddr *dp, *dm; 313 const struct protosw *psw; 314 void *arg; 315 { 316 struct encaptab *ep; 317 int error; 318 int s; 319 320 s = splnet(); 321 /* sanity check on args */ 322 if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst)) { 323 error = EINVAL; 324 goto fail; 325 } 326 if (sp->sa_len != dp->sa_len) { 327 error = EINVAL; 328 goto fail; 329 } 330 if (af != sp->sa_family || af != dp->sa_family) { 331 error = EINVAL; 332 goto fail; 333 } 334 335 /* check if anyone have already attached with exactly same config */ 336 for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) { 337 if (ep->af != af) 338 continue; 339 if (ep->proto != proto) 340 continue; 341 if (ep->src.ss_len != sp->sa_len || 342 bcmp(&ep->src, sp, sp->sa_len) != 0 || 343 bcmp(&ep->srcmask, sm, sp->sa_len) != 0) 344 continue; 345 if (ep->dst.ss_len != dp->sa_len || 346 bcmp(&ep->dst, dp, dp->sa_len) != 0 || 347 bcmp(&ep->dstmask, dm, dp->sa_len) != 0) 348 continue; 349 350 error = EEXIST; 351 goto fail; 352 } 353 354 ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT); /*XXX*/ 355 if (ep == NULL) { 356 error = ENOBUFS; 357 goto fail; 358 } 359 bzero(ep, sizeof(*ep)); 360 361 ep->af = af; 362 ep->proto = proto; 363 bcopy(sp, &ep->src, sp->sa_len); 364 bcopy(sm, &ep->srcmask, sp->sa_len); 365 bcopy(dp, &ep->dst, dp->sa_len); 366 bcopy(dm, &ep->dstmask, dp->sa_len); 367 ep->psw = psw; 368 ep->arg = arg; 369 370 encap_add(ep); 371 372 error = 0; 373 splx(s); 374 return ep; 375 376 fail: 377 splx(s); 378 return NULL; 379 } 380 381 const struct encaptab * 382 encap_attach_func(af, proto, func, psw, arg) 383 int af; 384 int proto; 385 int (*func) __P((const struct mbuf *, int, int, void *)); 386 const struct protosw *psw; 387 void *arg; 388 { 389 struct encaptab *ep; 390 int error; 391 int s; 392 393 s = splnet(); 394 /* sanity check on args */ 395 if (!func) { 396 error = EINVAL; 397 goto fail; 398 } 399 400 ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT); /*XXX*/ 401 if (ep == NULL) { 402 error = ENOBUFS; 403 goto fail; 404 } 405 bzero(ep, sizeof(*ep)); 406 407 ep->af = af; 408 ep->proto = proto; 409 ep->func = func; 410 ep->psw = psw; 411 ep->arg = arg; 412 413 encap_add(ep); 414 415 error = 0; 416 splx(s); 417 return ep; 418 419 fail: 420 splx(s); 421 return NULL; 422 } 423 424 int 425 encap_detach(cookie) 426 const struct encaptab *cookie; 427 { 428 const struct encaptab *ep = cookie; 429 struct encaptab *p; 430 431 for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) { 432 if (p == ep) { 433 LIST_REMOVE(p, chain); 434 free(p, M_NETADDR); /*XXX*/ 435 return 0; 436 } 437 } 438 439 return EINVAL; 440 } 441 442 static int 443 mask_match(ep, sp, dp) 444 const struct encaptab *ep; 445 const struct sockaddr *sp; 446 const struct sockaddr *dp; 447 { 448 struct sockaddr_storage s; 449 struct sockaddr_storage d; 450 int i; 451 const u_int8_t *p, *q; 452 u_int8_t *r; 453 int matchlen; 454 455 if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d)) 456 return 0; 457 if (sp->sa_family != ep->af || dp->sa_family != ep->af) 458 return 0; 459 if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len) 460 return 0; 461 462 matchlen = 0; 463 464 p = (const u_int8_t *)sp; 465 q = (const u_int8_t *)&ep->srcmask; 466 r = (u_int8_t *)&s; 467 for (i = 0 ; i < sp->sa_len; i++) { 468 r[i] = p[i] & q[i]; 469 /* XXX estimate */ 470 matchlen += (q[i] ? 8 : 0); 471 } 472 473 p = (const u_int8_t *)dp; 474 q = (const u_int8_t *)&ep->dstmask; 475 r = (u_int8_t *)&d; 476 for (i = 0 ; i < dp->sa_len; i++) { 477 r[i] = p[i] & q[i]; 478 /* XXX rough estimate */ 479 matchlen += (q[i] ? 8 : 0); 480 } 481 482 /* need to overwrite len/family portion as we don't compare them */ 483 s.ss_len = sp->sa_len; 484 s.ss_family = sp->sa_family; 485 d.ss_len = dp->sa_len; 486 d.ss_family = dp->sa_family; 487 488 if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 && 489 bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) { 490 return matchlen; 491 } else 492 return 0; 493 } 494 495 static void 496 encap_fillarg(m, ep) 497 struct mbuf *m; 498 const struct encaptab *ep; 499 { 500 #if 0 501 m->m_pkthdr.aux = ep->arg; 502 #else 503 struct mbuf *n; 504 505 n = m_aux_add(m, AF_INET, IPPROTO_IPV4); 506 if (n) { 507 *mtod(n, void **) = ep->arg; 508 n->m_len = sizeof(void *); 509 } 510 #endif 511 } 512 513 void * 514 encap_getarg(m) 515 struct mbuf *m; 516 { 517 void *p; 518 #if 0 519 p = m->m_pkthdr.aux; 520 m->m_pkthdr.aux = NULL; 521 return p; 522 #else 523 struct mbuf *n; 524 525 p = NULL; 526 n = m_aux_find(m, AF_INET, IPPROTO_IPV4); 527 if (n) { 528 if (n->m_len == sizeof(void *)) 529 p = *mtod(n, void **); 530 m_aux_delete(m, n); 531 } 532 return p; 533 #endif 534 } 535