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 1.3 2003/07/29 12:51:30 hmp 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 __P((struct encaptab *)); 98 static int mask_match __P((const struct encaptab *, const struct sockaddr *, 99 const struct sockaddr *)); 100 static void encap_fillarg __P((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, int off, int proto) 134 { 135 struct ip *ip; 136 struct sockaddr_in s, d; 137 const struct ipprotosw *psw; 138 struct encaptab *ep, *match; 139 int prio, matchprio; 140 141 ip = mtod(m, struct ip *); 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 for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, 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 = (const struct ipprotosw *)match->psw; 199 if (psw && psw->pr_input) { 200 encap_fillarg(m, match); 201 (*psw->pr_input)(m, off, proto); 202 } else 203 m_freem(m); 204 return; 205 } 206 207 /* for backward compatibility */ 208 if (proto == IPPROTO_IPV4 && ipip_input) { 209 ipip_input(m, off, proto); 210 return; 211 } 212 213 /* last resort: inject to raw socket */ 214 rip_input(m, off, proto); 215 } 216 #endif 217 218 #ifdef INET6 219 int 220 encap6_input(mp, offp, proto) 221 struct mbuf **mp; 222 int *offp; 223 int proto; 224 { 225 struct mbuf *m = *mp; 226 struct ip6_hdr *ip6; 227 struct sockaddr_in6 s, d; 228 const struct ip6protosw *psw; 229 struct encaptab *ep, *match; 230 int prio, matchprio; 231 232 ip6 = mtod(m, struct ip6_hdr *); 233 234 bzero(&s, sizeof(s)); 235 s.sin6_family = AF_INET6; 236 s.sin6_len = sizeof(struct sockaddr_in6); 237 s.sin6_addr = ip6->ip6_src; 238 bzero(&d, sizeof(d)); 239 d.sin6_family = AF_INET6; 240 d.sin6_len = sizeof(struct sockaddr_in6); 241 d.sin6_addr = ip6->ip6_dst; 242 243 match = NULL; 244 matchprio = 0; 245 for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) { 246 if (ep->af != AF_INET6) 247 continue; 248 if (ep->proto >= 0 && ep->proto != proto) 249 continue; 250 if (ep->func) 251 prio = (*ep->func)(m, *offp, proto, ep->arg); 252 else { 253 /* 254 * it's inbound traffic, we need to match in reverse 255 * order 256 */ 257 prio = mask_match(ep, (struct sockaddr *)&d, 258 (struct sockaddr *)&s); 259 } 260 261 /* see encap4_input() for issues here */ 262 if (prio <= 0) 263 continue; 264 if (prio > matchprio) { 265 matchprio = prio; 266 match = ep; 267 } 268 } 269 270 if (match) { 271 /* found a match */ 272 psw = (const struct ip6protosw *)match->psw; 273 if (psw && psw->pr_input) { 274 encap_fillarg(m, match); 275 return (*psw->pr_input)(mp, offp, proto); 276 } else { 277 m_freem(m); 278 return IPPROTO_DONE; 279 } 280 } 281 282 /* last resort: inject to raw socket */ 283 return rip6_input(mp, offp, proto); 284 } 285 #endif 286 287 static void 288 encap_add(ep) 289 struct encaptab *ep; 290 { 291 292 LIST_INSERT_HEAD(&encaptab, ep, chain); 293 } 294 295 /* 296 * sp (src ptr) is always my side, and dp (dst ptr) is always remote side. 297 * length of mask (sm and dm) is assumed to be same as sp/dp. 298 * Return value will be necessary as input (cookie) for encap_detach(). 299 */ 300 const struct encaptab * 301 encap_attach(af, proto, sp, sm, dp, dm, psw, arg) 302 int af; 303 int proto; 304 const struct sockaddr *sp, *sm; 305 const struct sockaddr *dp, *dm; 306 const struct protosw *psw; 307 void *arg; 308 { 309 struct encaptab *ep; 310 int error; 311 int s; 312 313 s = splnet(); 314 /* sanity check on args */ 315 if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst)) { 316 error = EINVAL; 317 goto fail; 318 } 319 if (sp->sa_len != dp->sa_len) { 320 error = EINVAL; 321 goto fail; 322 } 323 if (af != sp->sa_family || af != dp->sa_family) { 324 error = EINVAL; 325 goto fail; 326 } 327 328 /* check if anyone have already attached with exactly same config */ 329 for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) { 330 if (ep->af != af) 331 continue; 332 if (ep->proto != proto) 333 continue; 334 if (ep->src.ss_len != sp->sa_len || 335 bcmp(&ep->src, sp, sp->sa_len) != 0 || 336 bcmp(&ep->srcmask, sm, sp->sa_len) != 0) 337 continue; 338 if (ep->dst.ss_len != dp->sa_len || 339 bcmp(&ep->dst, dp, dp->sa_len) != 0 || 340 bcmp(&ep->dstmask, dm, dp->sa_len) != 0) 341 continue; 342 343 error = EEXIST; 344 goto fail; 345 } 346 347 ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT); /*XXX*/ 348 if (ep == NULL) { 349 error = ENOBUFS; 350 goto fail; 351 } 352 bzero(ep, sizeof(*ep)); 353 354 ep->af = af; 355 ep->proto = proto; 356 bcopy(sp, &ep->src, sp->sa_len); 357 bcopy(sm, &ep->srcmask, sp->sa_len); 358 bcopy(dp, &ep->dst, dp->sa_len); 359 bcopy(dm, &ep->dstmask, dp->sa_len); 360 ep->psw = psw; 361 ep->arg = arg; 362 363 encap_add(ep); 364 365 error = 0; 366 splx(s); 367 return ep; 368 369 fail: 370 splx(s); 371 return NULL; 372 } 373 374 const struct encaptab * 375 encap_attach_func(af, proto, func, psw, arg) 376 int af; 377 int proto; 378 int (*func) __P((const struct mbuf *, int, int, void *)); 379 const struct protosw *psw; 380 void *arg; 381 { 382 struct encaptab *ep; 383 int error; 384 int s; 385 386 s = splnet(); 387 /* sanity check on args */ 388 if (!func) { 389 error = EINVAL; 390 goto fail; 391 } 392 393 ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT); /*XXX*/ 394 if (ep == NULL) { 395 error = ENOBUFS; 396 goto fail; 397 } 398 bzero(ep, sizeof(*ep)); 399 400 ep->af = af; 401 ep->proto = proto; 402 ep->func = func; 403 ep->psw = psw; 404 ep->arg = arg; 405 406 encap_add(ep); 407 408 error = 0; 409 splx(s); 410 return ep; 411 412 fail: 413 splx(s); 414 return NULL; 415 } 416 417 int 418 encap_detach(cookie) 419 const struct encaptab *cookie; 420 { 421 const struct encaptab *ep = cookie; 422 struct encaptab *p; 423 424 for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) { 425 if (p == ep) { 426 LIST_REMOVE(p, chain); 427 free(p, M_NETADDR); /*XXX*/ 428 return 0; 429 } 430 } 431 432 return EINVAL; 433 } 434 435 static int 436 mask_match(ep, sp, dp) 437 const struct encaptab *ep; 438 const struct sockaddr *sp; 439 const struct sockaddr *dp; 440 { 441 struct sockaddr_storage s; 442 struct sockaddr_storage d; 443 int i; 444 const u_int8_t *p, *q; 445 u_int8_t *r; 446 int matchlen; 447 448 if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d)) 449 return 0; 450 if (sp->sa_family != ep->af || dp->sa_family != ep->af) 451 return 0; 452 if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len) 453 return 0; 454 455 matchlen = 0; 456 457 p = (const u_int8_t *)sp; 458 q = (const u_int8_t *)&ep->srcmask; 459 r = (u_int8_t *)&s; 460 for (i = 0 ; i < sp->sa_len; i++) { 461 r[i] = p[i] & q[i]; 462 /* XXX estimate */ 463 matchlen += (q[i] ? 8 : 0); 464 } 465 466 p = (const u_int8_t *)dp; 467 q = (const u_int8_t *)&ep->dstmask; 468 r = (u_int8_t *)&d; 469 for (i = 0 ; i < dp->sa_len; i++) { 470 r[i] = p[i] & q[i]; 471 /* XXX rough estimate */ 472 matchlen += (q[i] ? 8 : 0); 473 } 474 475 /* need to overwrite len/family portion as we don't compare them */ 476 s.ss_len = sp->sa_len; 477 s.ss_family = sp->sa_family; 478 d.ss_len = dp->sa_len; 479 d.ss_family = dp->sa_family; 480 481 if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 && 482 bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) { 483 return matchlen; 484 } else 485 return 0; 486 } 487 488 static void 489 encap_fillarg(m, ep) 490 struct mbuf *m; 491 const struct encaptab *ep; 492 { 493 struct m_tag *tag; 494 495 tag = m_tag_get(PACKET_TAG_ENCAP, sizeof (void*), M_DONTWAIT); 496 if (tag) { 497 *(void**)(tag+1) = ep->arg; 498 m_tag_prepend(m, tag); 499 } 500 } 501 502 void * 503 encap_getarg(m) 504 struct mbuf *m; 505 { 506 void *p = NULL; 507 struct m_tag *tag; 508 509 tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL); 510 if (tag) { 511 p = *(void**)(tag+1); 512 m_tag_delete(m, tag); 513 } 514 return p; 515 } 516