1 /* $FreeBSD: src/sys/netinet/ip_encap.c,v 1.1.2.5 2003/01/23 21:06:45 sam Exp $ */ 2 /* $DragonFly: src/sys/netinet/ip_encap.c,v 1.8 2004/06/03 18:30:03 joerg Exp $ */ 3 /* $KAME: ip_encap.c,v 1.41 2001/03/15 08:35:08 itojun Exp $ */ 4 5 /* 6 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the project nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 /* 34 * My grandfather said that there's a devil inside tunnelling technology... 35 * 36 * We have surprisingly many protocols that want packets with IP protocol 37 * #4 or #41. Here's a list of protocols that want protocol #41: 38 * RFC1933 configured tunnel 39 * RFC1933 automatic tunnel 40 * RFC2401 IPsec tunnel 41 * RFC2473 IPv6 generic packet tunnelling 42 * RFC2529 6over4 tunnel 43 * mobile-ip6 (uses RFC2473) 44 * RFC3056 6to4 tunnel 45 * isatap tunnel 46 * Here's a list of protocol that want protocol #4: 47 * RFC1853 IPv4-in-IPv4 tunnelling 48 * RFC2003 IPv4 encapsulation within IPv4 49 * RFC2344 reverse tunnelling for mobile-ip4 50 * RFC2401 IPsec tunnel 51 * Well, what can I say. They impose different en/decapsulation mechanism 52 * from each other, so they need separate protocol handler. The only one 53 * we can easily determine by protocol # is IPsec, which always has 54 * AH/ESP/IPComp header right after outer IP header. 55 * 56 * So, clearly good old protosw does not work for protocol #4 and #41. 57 * The code will let you match protocol via src/dst address pair. 58 */ 59 /* XXX is M_NETADDR correct? */ 60 61 #include "opt_inet.h" 62 #include "opt_inet6.h" 63 64 #include <sys/param.h> 65 #include <sys/systm.h> 66 #include <sys/socket.h> 67 #include <sys/sockio.h> 68 #include <sys/mbuf.h> 69 #include <sys/errno.h> 70 #include <sys/protosw.h> 71 #include <sys/queue.h> 72 73 #include <net/if.h> 74 #include <net/route.h> 75 76 #include <netinet/in.h> 77 #include <netinet/in_systm.h> 78 #include <netinet/ip.h> 79 #include <netinet/ip_var.h> 80 #include <netinet/ip_encap.h> 81 #include <netinet/ipprotosw.h> 82 83 #ifdef INET6 84 #include <netinet/ip6.h> 85 #include <netinet6/ip6_var.h> 86 #include <netinet6/ip6protosw.h> 87 #endif 88 89 #include <machine/stdarg.h> 90 91 #include <net/net_osdep.h> 92 93 #include <sys/kernel.h> 94 #include <sys/malloc.h> 95 MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure"); 96 97 static void encap_add (struct encaptab *); 98 static int mask_match (const struct encaptab *, const struct sockaddr *, 99 const struct sockaddr *); 100 static void encap_fillarg (struct mbuf *, const struct encaptab *); 101 102 #ifndef LIST_HEAD_INITIALIZER 103 /* rely upon BSS initialization */ 104 LIST_HEAD(, encaptab) encaptab; 105 #else 106 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab); 107 #endif 108 109 void (*ipip_input)(struct mbuf *, int, int); /* hook for mrouting */ 110 111 void 112 encap_init() 113 { 114 static int initialized = 0; 115 116 if (initialized) 117 return; 118 initialized++; 119 #if 0 120 /* 121 * we cannot use LIST_INIT() here, since drivers may want to call 122 * encap_attach(), on driver attach. encap_init() will be called 123 * on AF_INET{,6} initialization, which happens after driver 124 * initialization - using LIST_INIT() here can nuke encap_attach() 125 * from drivers. 126 */ 127 LIST_INIT(&encaptab); 128 #endif 129 } 130 131 #ifdef INET 132 void 133 encap4_input(struct mbuf *m, ...) 134 { 135 int off, proto; 136 struct ip *ip; 137 struct sockaddr_in s, d; 138 const struct ipprotosw *psw; 139 struct encaptab *ep, *match; 140 int prio, matchprio; 141 __va_list ap; 142 143 __va_start(ap, m); 144 off = __va_arg(ap, int); 145 proto = __va_arg(ap, int); 146 __va_end(ap); 147 148 ip = mtod(m, struct ip *); 149 150 bzero(&s, sizeof(s)); 151 s.sin_family = AF_INET; 152 s.sin_len = sizeof(struct sockaddr_in); 153 s.sin_addr = ip->ip_src; 154 bzero(&d, sizeof(d)); 155 d.sin_family = AF_INET; 156 d.sin_len = sizeof(struct sockaddr_in); 157 d.sin_addr = ip->ip_dst; 158 159 match = NULL; 160 matchprio = 0; 161 for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) { 162 if (ep->af != AF_INET) 163 continue; 164 if (ep->proto >= 0 && ep->proto != proto) 165 continue; 166 if (ep->func) 167 prio = (*ep->func)(m, off, proto, ep->arg); 168 else { 169 /* 170 * it's inbound traffic, we need to match in reverse 171 * order 172 */ 173 prio = mask_match(ep, (struct sockaddr *)&d, 174 (struct sockaddr *)&s); 175 } 176 177 /* 178 * We prioritize the matches by using bit length of the 179 * matches. mask_match() and user-supplied matching function 180 * should return the bit length of the matches (for example, 181 * if both src/dst are matched for IPv4, 64 should be returned). 182 * 0 or negative return value means "it did not match". 183 * 184 * The question is, since we have two "mask" portion, we 185 * cannot really define total order between entries. 186 * For example, which of these should be preferred? 187 * mask_match() returns 48 (32 + 16) for both of them. 188 * src=3ffe::/16, dst=3ffe:501::/32 189 * src=3ffe:501::/32, dst=3ffe::/16 190 * 191 * We need to loop through all the possible candidates 192 * to get the best match - the search takes O(n) for 193 * n attachments (i.e. interfaces). 194 */ 195 if (prio <= 0) 196 continue; 197 if (prio > matchprio) { 198 matchprio = prio; 199 match = ep; 200 } 201 } 202 203 if (match) { 204 /* found a match, "match" has the best one */ 205 psw = (const struct ipprotosw *)match->psw; 206 if (psw && psw->pr_input) { 207 encap_fillarg(m, match); 208 (*psw->pr_input)(m, off, proto); 209 } else 210 m_freem(m); 211 return; 212 } 213 214 /* for backward compatibility */ 215 if (proto == IPPROTO_IPV4 && ipip_input) { 216 ipip_input(m, off, proto); 217 return; 218 } 219 220 /* last resort: inject to raw socket */ 221 rip_input(m, off, proto); 222 } 223 #endif 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_INTWAIT | M_ZERO | M_NULLOK); 355 if (ep == NULL) { 356 error = ENOBUFS; 357 goto fail; 358 } 359 360 ep->af = af; 361 ep->proto = proto; 362 bcopy(sp, &ep->src, sp->sa_len); 363 bcopy(sm, &ep->srcmask, sp->sa_len); 364 bcopy(dp, &ep->dst, dp->sa_len); 365 bcopy(dm, &ep->dstmask, dp->sa_len); 366 ep->psw = psw; 367 ep->arg = arg; 368 369 encap_add(ep); 370 371 error = 0; 372 splx(s); 373 return ep; 374 375 fail: 376 splx(s); 377 return NULL; 378 } 379 380 const struct encaptab * 381 encap_attach_func(af, proto, func, psw, arg) 382 int af; 383 int proto; 384 int (*func) (const struct mbuf *, int, int, void *); 385 const struct protosw *psw; 386 void *arg; 387 { 388 struct encaptab *ep; 389 int error; 390 int s; 391 392 s = splnet(); 393 /* sanity check on args */ 394 if (!func) { 395 error = EINVAL; 396 goto fail; 397 } 398 399 ep = malloc(sizeof(*ep), M_NETADDR, M_INTWAIT | M_ZERO | M_NULLOK); 400 if (ep == NULL) { 401 error = ENOBUFS; 402 goto fail; 403 } 404 405 ep->af = af; 406 ep->proto = proto; 407 ep->func = func; 408 ep->psw = psw; 409 ep->arg = arg; 410 411 encap_add(ep); 412 413 error = 0; 414 splx(s); 415 return ep; 416 417 fail: 418 splx(s); 419 return NULL; 420 } 421 422 int 423 encap_detach(cookie) 424 const struct encaptab *cookie; 425 { 426 const struct encaptab *ep = cookie; 427 struct encaptab *p; 428 429 for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) { 430 if (p == ep) { 431 LIST_REMOVE(p, chain); 432 free(p, M_NETADDR); /*XXX*/ 433 return 0; 434 } 435 } 436 437 return EINVAL; 438 } 439 440 static int 441 mask_match(ep, sp, dp) 442 const struct encaptab *ep; 443 const struct sockaddr *sp; 444 const struct sockaddr *dp; 445 { 446 struct sockaddr_storage s; 447 struct sockaddr_storage d; 448 int i; 449 const u_int8_t *p, *q; 450 u_int8_t *r; 451 int matchlen; 452 453 if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d)) 454 return 0; 455 if (sp->sa_family != ep->af || dp->sa_family != ep->af) 456 return 0; 457 if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len) 458 return 0; 459 460 matchlen = 0; 461 462 p = (const u_int8_t *)sp; 463 q = (const u_int8_t *)&ep->srcmask; 464 r = (u_int8_t *)&s; 465 for (i = 0 ; i < sp->sa_len; i++) { 466 r[i] = p[i] & q[i]; 467 /* XXX estimate */ 468 matchlen += (q[i] ? 8 : 0); 469 } 470 471 p = (const u_int8_t *)dp; 472 q = (const u_int8_t *)&ep->dstmask; 473 r = (u_int8_t *)&d; 474 for (i = 0 ; i < dp->sa_len; i++) { 475 r[i] = p[i] & q[i]; 476 /* XXX rough estimate */ 477 matchlen += (q[i] ? 8 : 0); 478 } 479 480 /* need to overwrite len/family portion as we don't compare them */ 481 s.ss_len = sp->sa_len; 482 s.ss_family = sp->sa_family; 483 d.ss_len = dp->sa_len; 484 d.ss_family = dp->sa_family; 485 486 if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 && 487 bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) { 488 return matchlen; 489 } else 490 return 0; 491 } 492 493 static void 494 encap_fillarg(m, ep) 495 struct mbuf *m; 496 const struct encaptab *ep; 497 { 498 struct m_tag *tag; 499 500 tag = m_tag_get(PACKET_TAG_ENCAP, sizeof (void*), MB_DONTWAIT); 501 if (tag) { 502 *(void**)(tag+1) = ep->arg; 503 m_tag_prepend(m, tag); 504 } 505 } 506 507 void * 508 encap_getarg(m) 509 struct mbuf *m; 510 { 511 void *p = NULL; 512 struct m_tag *tag; 513 514 tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL); 515 if (tag) { 516 p = *(void**)(tag+1); 517 m_tag_delete(m, tag); 518 } 519 return p; 520 } 521