1 /* $FreeBSD$ */ 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 * 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 #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 static MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure"); 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 void 108 encap_init() 109 { 110 static int initialized = 0; 111 112 if (initialized) 113 return; 114 initialized++; 115 #if 0 116 /* 117 * we cannot use LIST_INIT() here, since drivers may want to call 118 * encap_attach(), on driver attach. encap_init() will be called 119 * on AF_INET{,6} initialization, which happens after driver 120 * initialization - using LIST_INIT() here can nuke encap_attach() 121 * from drivers. 122 */ 123 LIST_INIT(&encaptab); 124 #endif 125 } 126 127 #ifdef INET 128 void 129 encap4_input(m, off) 130 struct mbuf *m; 131 int off; 132 { 133 struct ip *ip; 134 int proto; 135 struct sockaddr_in s, d; 136 const struct protosw *psw; 137 struct encaptab *ep, *match; 138 int prio, matchprio; 139 140 ip = mtod(m, struct ip *); 141 proto = ip->ip_p; 142 143 bzero(&s, sizeof(s)); 144 s.sin_family = AF_INET; 145 s.sin_len = sizeof(struct sockaddr_in); 146 s.sin_addr = ip->ip_src; 147 bzero(&d, sizeof(d)); 148 d.sin_family = AF_INET; 149 d.sin_len = sizeof(struct sockaddr_in); 150 d.sin_addr = ip->ip_dst; 151 152 match = NULL; 153 matchprio = 0; 154 LIST_FOREACH(ep, &encaptab, chain) { 155 if (ep->af != AF_INET) 156 continue; 157 if (ep->proto >= 0 && ep->proto != proto) 158 continue; 159 if (ep->func) 160 prio = (*ep->func)(m, off, proto, ep->arg); 161 else { 162 /* 163 * it's inbound traffic, we need to match in reverse 164 * order 165 */ 166 prio = mask_match(ep, (struct sockaddr *)&d, 167 (struct sockaddr *)&s); 168 } 169 170 /* 171 * We prioritize the matches by using bit length of the 172 * matches. mask_match() and user-supplied matching function 173 * should return the bit length of the matches (for example, 174 * if both src/dst are matched for IPv4, 64 should be returned). 175 * 0 or negative return value means "it did not match". 176 * 177 * The question is, since we have two "mask" portion, we 178 * cannot really define total order between entries. 179 * For example, which of these should be preferred? 180 * mask_match() returns 48 (32 + 16) for both of them. 181 * src=3ffe::/16, dst=3ffe:501::/32 182 * src=3ffe:501::/32, dst=3ffe::/16 183 * 184 * We need to loop through all the possible candidates 185 * to get the best match - the search takes O(n) for 186 * n attachments (i.e. interfaces). 187 */ 188 if (prio <= 0) 189 continue; 190 if (prio > matchprio) { 191 matchprio = prio; 192 match = ep; 193 } 194 } 195 196 if (match) { 197 /* found a match, "match" has the best one */ 198 psw = match->psw; 199 if (psw && psw->pr_input) { 200 encap_fillarg(m, match); 201 (*psw->pr_input)(m, off); 202 } else 203 m_freem(m); 204 return; 205 } 206 207 /* last resort: inject to raw socket */ 208 rip_input(m, off); 209 } 210 #endif 211 212 #ifdef INET6 213 int 214 encap6_input(mp, offp, proto) 215 struct mbuf **mp; 216 int *offp; 217 int proto; 218 { 219 struct mbuf *m = *mp; 220 struct ip6_hdr *ip6; 221 struct sockaddr_in6 s, d; 222 const struct ip6protosw *psw; 223 struct encaptab *ep, *match; 224 int prio, matchprio; 225 226 ip6 = mtod(m, struct ip6_hdr *); 227 228 bzero(&s, sizeof(s)); 229 s.sin6_family = AF_INET6; 230 s.sin6_len = sizeof(struct sockaddr_in6); 231 s.sin6_addr = ip6->ip6_src; 232 bzero(&d, sizeof(d)); 233 d.sin6_family = AF_INET6; 234 d.sin6_len = sizeof(struct sockaddr_in6); 235 d.sin6_addr = ip6->ip6_dst; 236 237 match = NULL; 238 matchprio = 0; 239 LIST_FOREACH(ep, &encaptab, chain) { 240 if (ep->af != AF_INET6) 241 continue; 242 if (ep->proto >= 0 && ep->proto != proto) 243 continue; 244 if (ep->func) 245 prio = (*ep->func)(m, *offp, proto, ep->arg); 246 else { 247 /* 248 * it's inbound traffic, we need to match in reverse 249 * order 250 */ 251 prio = mask_match(ep, (struct sockaddr *)&d, 252 (struct sockaddr *)&s); 253 } 254 255 /* see encap4_input() for issues here */ 256 if (prio <= 0) 257 continue; 258 if (prio > matchprio) { 259 matchprio = prio; 260 match = ep; 261 } 262 } 263 264 if (match) { 265 /* found a match */ 266 psw = (const struct ip6protosw *)match->psw; 267 if (psw && psw->pr_input) { 268 encap_fillarg(m, match); 269 return (*psw->pr_input)(mp, offp, proto); 270 } else { 271 m_freem(m); 272 return IPPROTO_DONE; 273 } 274 } 275 276 /* last resort: inject to raw socket */ 277 return rip6_input(mp, offp, proto); 278 } 279 #endif 280 281 static void 282 encap_add(ep) 283 struct encaptab *ep; 284 { 285 286 LIST_INSERT_HEAD(&encaptab, ep, chain); 287 } 288 289 /* 290 * sp (src ptr) is always my side, and dp (dst ptr) is always remote side. 291 * length of mask (sm and dm) is assumed to be same as sp/dp. 292 * Return value will be necessary as input (cookie) for encap_detach(). 293 */ 294 const struct encaptab * 295 encap_attach(af, proto, sp, sm, dp, dm, psw, arg) 296 int af; 297 int proto; 298 const struct sockaddr *sp, *sm; 299 const struct sockaddr *dp, *dm; 300 const struct protosw *psw; 301 void *arg; 302 { 303 struct encaptab *ep; 304 int error; 305 int s; 306 307 s = splnet(); 308 /* sanity check on args */ 309 if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst)) { 310 error = EINVAL; 311 goto fail; 312 } 313 if (sp->sa_len != dp->sa_len) { 314 error = EINVAL; 315 goto fail; 316 } 317 if (af != sp->sa_family || af != dp->sa_family) { 318 error = EINVAL; 319 goto fail; 320 } 321 322 /* check if anyone have already attached with exactly same config */ 323 LIST_FOREACH(ep, &encaptab, chain) { 324 if (ep->af != af) 325 continue; 326 if (ep->proto != proto) 327 continue; 328 if (ep->src.ss_len != sp->sa_len || 329 bcmp(&ep->src, sp, sp->sa_len) != 0 || 330 bcmp(&ep->srcmask, sm, sp->sa_len) != 0) 331 continue; 332 if (ep->dst.ss_len != dp->sa_len || 333 bcmp(&ep->dst, dp, dp->sa_len) != 0 || 334 bcmp(&ep->dstmask, dm, dp->sa_len) != 0) 335 continue; 336 337 error = EEXIST; 338 goto fail; 339 } 340 341 ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT); /*XXX*/ 342 if (ep == NULL) { 343 error = ENOBUFS; 344 goto fail; 345 } 346 bzero(ep, sizeof(*ep)); 347 348 ep->af = af; 349 ep->proto = proto; 350 bcopy(sp, &ep->src, sp->sa_len); 351 bcopy(sm, &ep->srcmask, sp->sa_len); 352 bcopy(dp, &ep->dst, dp->sa_len); 353 bcopy(dm, &ep->dstmask, dp->sa_len); 354 ep->psw = psw; 355 ep->arg = arg; 356 357 encap_add(ep); 358 359 error = 0; 360 splx(s); 361 return ep; 362 363 fail: 364 splx(s); 365 return NULL; 366 } 367 368 const struct encaptab * 369 encap_attach_func(af, proto, func, psw, arg) 370 int af; 371 int proto; 372 int (*func)(const struct mbuf *, int, int, void *); 373 const struct protosw *psw; 374 void *arg; 375 { 376 struct encaptab *ep; 377 int error; 378 int s; 379 380 s = splnet(); 381 /* sanity check on args */ 382 if (!func) { 383 error = EINVAL; 384 goto fail; 385 } 386 387 ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT); /*XXX*/ 388 if (ep == NULL) { 389 error = ENOBUFS; 390 goto fail; 391 } 392 bzero(ep, sizeof(*ep)); 393 394 ep->af = af; 395 ep->proto = proto; 396 ep->func = func; 397 ep->psw = psw; 398 ep->arg = arg; 399 400 encap_add(ep); 401 402 error = 0; 403 splx(s); 404 return ep; 405 406 fail: 407 splx(s); 408 return NULL; 409 } 410 411 int 412 encap_detach(cookie) 413 const struct encaptab *cookie; 414 { 415 const struct encaptab *ep = cookie; 416 struct encaptab *p; 417 418 LIST_FOREACH(p, &encaptab, chain) { 419 if (p == ep) { 420 LIST_REMOVE(p, chain); 421 free(p, M_NETADDR); /*XXX*/ 422 return 0; 423 } 424 } 425 426 return EINVAL; 427 } 428 429 static int 430 mask_match(ep, sp, dp) 431 const struct encaptab *ep; 432 const struct sockaddr *sp; 433 const struct sockaddr *dp; 434 { 435 struct sockaddr_storage s; 436 struct sockaddr_storage d; 437 int i; 438 const u_int8_t *p, *q; 439 u_int8_t *r; 440 int matchlen; 441 442 if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d)) 443 return 0; 444 if (sp->sa_family != ep->af || dp->sa_family != ep->af) 445 return 0; 446 if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len) 447 return 0; 448 449 matchlen = 0; 450 451 p = (const u_int8_t *)sp; 452 q = (const u_int8_t *)&ep->srcmask; 453 r = (u_int8_t *)&s; 454 for (i = 0 ; i < sp->sa_len; i++) { 455 r[i] = p[i] & q[i]; 456 /* XXX estimate */ 457 matchlen += (q[i] ? 8 : 0); 458 } 459 460 p = (const u_int8_t *)dp; 461 q = (const u_int8_t *)&ep->dstmask; 462 r = (u_int8_t *)&d; 463 for (i = 0 ; i < dp->sa_len; i++) { 464 r[i] = p[i] & q[i]; 465 /* XXX rough estimate */ 466 matchlen += (q[i] ? 8 : 0); 467 } 468 469 /* need to overwrite len/family portion as we don't compare them */ 470 s.ss_len = sp->sa_len; 471 s.ss_family = sp->sa_family; 472 d.ss_len = dp->sa_len; 473 d.ss_family = dp->sa_family; 474 475 if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 && 476 bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) { 477 return matchlen; 478 } else 479 return 0; 480 } 481 482 static void 483 encap_fillarg(m, ep) 484 struct mbuf *m; 485 const struct encaptab *ep; 486 { 487 #if 0 488 m->m_pkthdr.aux = ep->arg; 489 #else 490 struct mbuf *n; 491 492 n = m_aux_add(m, AF_INET, IPPROTO_IPV4); 493 if (n) { 494 *mtod(n, void **) = ep->arg; 495 n->m_len = sizeof(void *); 496 } 497 #endif 498 } 499 500 void * 501 encap_getarg(m) 502 struct mbuf *m; 503 { 504 void *p; 505 #if 0 506 p = m->m_pkthdr.aux; 507 m->m_pkthdr.aux = NULL; 508 return p; 509 #else 510 struct mbuf *n; 511 512 p = NULL; 513 n = m_aux_find(m, AF_INET, IPPROTO_IPV4); 514 if (n) { 515 if (n->m_len == sizeof(void *)) 516 p = *mtod(n, void **); 517 m_aux_delete(m, n); 518 } 519 return p; 520 #endif 521 } 522