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 1.15 2006/09/05 00:55:48 dillon 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 82 #ifdef INET6 83 #include <netinet/ip6.h> 84 #include <netinet6/ip6_var.h> 85 #include <netinet6/ip6protosw.h> 86 #endif 87 88 #include <machine/stdarg.h> 89 90 #include <net/net_osdep.h> 91 92 #include <sys/kernel.h> 93 #include <sys/malloc.h> 94 #include <sys/thread2.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(void) 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 protosw *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 = 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(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 ip6protosw *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 = (const struct ip6protosw *)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 int error; 310 311 crit_enter(); 312 /* sanity check on args */ 313 if (sp->sa_len > sizeof ep->src || dp->sa_len > sizeof ep->dst) { 314 error = EINVAL; 315 goto fail; 316 } 317 if (sp->sa_len != dp->sa_len) { 318 error = EINVAL; 319 goto fail; 320 } 321 if (af != sp->sa_family || af != dp->sa_family) { 322 error = EINVAL; 323 goto fail; 324 } 325 326 /* check if anyone have already attached with exactly same config */ 327 for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) { 328 if (ep->af != af) 329 continue; 330 if (ep->proto != proto) 331 continue; 332 if (ep->src.ss_len != sp->sa_len || 333 bcmp(&ep->src, sp, sp->sa_len) != 0 || 334 bcmp(&ep->srcmask, sm, sp->sa_len) != 0) 335 continue; 336 if (ep->dst.ss_len != dp->sa_len || 337 bcmp(&ep->dst, dp, dp->sa_len) != 0 || 338 bcmp(&ep->dstmask, dm, dp->sa_len) != 0) 339 continue; 340 341 error = EEXIST; 342 goto fail; 343 } 344 345 ep = kmalloc(sizeof *ep, M_NETADDR, M_INTWAIT | M_ZERO | M_NULLOK); 346 if (ep == NULL) { 347 error = ENOBUFS; 348 goto fail; 349 } 350 351 ep->af = af; 352 ep->proto = proto; 353 bcopy(sp, &ep->src, sp->sa_len); 354 bcopy(sm, &ep->srcmask, sp->sa_len); 355 bcopy(dp, &ep->dst, dp->sa_len); 356 bcopy(dm, &ep->dstmask, dp->sa_len); 357 ep->psw = psw; 358 ep->arg = arg; 359 360 encap_add(ep); 361 362 error = 0; 363 crit_exit(); 364 return ep; 365 366 fail: 367 crit_exit(); 368 return NULL; 369 } 370 371 const struct encaptab * 372 encap_attach_func(int af, int proto, 373 int (*func)(const struct mbuf *, int, int, void *), 374 const struct protosw *psw, void *arg) 375 { 376 struct encaptab *ep; 377 int error; 378 379 crit_enter(); 380 /* sanity check on args */ 381 if (!func) { 382 error = EINVAL; 383 goto fail; 384 } 385 386 ep = kmalloc(sizeof *ep, M_NETADDR, M_INTWAIT | M_ZERO | M_NULLOK); 387 if (ep == NULL) { 388 error = ENOBUFS; 389 goto fail; 390 } 391 392 ep->af = af; 393 ep->proto = proto; 394 ep->func = func; 395 ep->psw = psw; 396 ep->arg = arg; 397 398 encap_add(ep); 399 400 error = 0; 401 crit_exit(); 402 return ep; 403 404 fail: 405 crit_exit(); 406 return NULL; 407 } 408 409 int 410 encap_detach(const struct encaptab *cookie) 411 { 412 const struct encaptab *ep = cookie; 413 struct encaptab *p; 414 415 for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) { 416 if (p == ep) { 417 LIST_REMOVE(p, chain); 418 kfree(p, M_NETADDR); /*XXX*/ 419 return 0; 420 } 421 } 422 423 return EINVAL; 424 } 425 426 static int 427 mask_match(const struct encaptab *ep, const struct sockaddr *sp, 428 const struct sockaddr *dp) 429 { 430 struct sockaddr_storage s; 431 struct sockaddr_storage d; 432 int i; 433 const u_int8_t *p, *q; 434 u_int8_t *r; 435 int matchlen; 436 437 if (sp->sa_len > sizeof s || dp->sa_len > sizeof d) 438 return 0; 439 if (sp->sa_family != ep->af || dp->sa_family != ep->af) 440 return 0; 441 if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len) 442 return 0; 443 444 matchlen = 0; 445 446 p = (const u_int8_t *)sp; 447 q = (const u_int8_t *)&ep->srcmask; 448 r = (u_int8_t *)&s; 449 for (i = 0 ; i < sp->sa_len; i++) { 450 r[i] = p[i] & q[i]; 451 /* XXX estimate */ 452 matchlen += (q[i] ? 8 : 0); 453 } 454 455 p = (const u_int8_t *)dp; 456 q = (const u_int8_t *)&ep->dstmask; 457 r = (u_int8_t *)&d; 458 for (i = 0 ; i < dp->sa_len; i++) { 459 r[i] = p[i] & q[i]; 460 /* XXX rough estimate */ 461 matchlen += (q[i] ? 8 : 0); 462 } 463 464 /* need to overwrite len/family portion as we don't compare them */ 465 s.ss_len = sp->sa_len; 466 s.ss_family = sp->sa_family; 467 d.ss_len = dp->sa_len; 468 d.ss_family = dp->sa_family; 469 470 if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 && 471 bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) { 472 return matchlen; 473 } else 474 return 0; 475 } 476 477 static void 478 encap_fillarg(struct mbuf *m, const struct encaptab *ep) 479 { 480 struct m_tag *tag; 481 482 tag = m_tag_get(PACKET_TAG_ENCAP, sizeof(void *), MB_DONTWAIT); 483 if (tag != NULL) { 484 *(void **)m_tag_data(tag) = ep->arg; 485 m_tag_prepend(m, tag); 486 } 487 } 488 489 void * 490 encap_getarg(struct mbuf *m) 491 { 492 void *p = NULL; 493 struct m_tag *tag; 494 495 tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL); 496 if (tag != NULL) { 497 p = *(void **)m_tag_data(tag); 498 m_tag_delete(m, tag); 499 } 500 return p; 501 } 502