1 /* $KAME: ip_encap.c,v 1.41 2001/03/15 08:35:08 itojun Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-3-Clause 5 * 6 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 7 * Copyright (c) 2018 Andrey V. Elsukov <ae@FreeBSD.org> 8 * All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the project nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 /* 35 * My grandfather said that there's a devil inside tunnelling technology... 36 * 37 * We have surprisingly many protocols that want packets with IP protocol 38 * #4 or #41. Here's a list of protocols that want protocol #41: 39 * RFC1933 configured tunnel 40 * RFC1933 automatic tunnel 41 * RFC2401 IPsec tunnel 42 * RFC2473 IPv6 generic packet tunnelling 43 * RFC2529 6over4 tunnel 44 * mobile-ip6 (uses RFC2473) 45 * RFC3056 6to4 tunnel 46 * isatap tunnel 47 * Here's a list of protocol that want protocol #4: 48 * RFC1853 IPv4-in-IPv4 tunnelling 49 * RFC2003 IPv4 encapsulation within IPv4 50 * RFC2344 reverse tunnelling for mobile-ip4 51 * RFC2401 IPsec tunnel 52 * Well, what can I say. They impose different en/decapsulation mechanism 53 * from each other, so they need separate protocol handler. The only one 54 * we can easily determine by protocol # is IPsec, which always has 55 * AH/ESP/IPComp header right after outer IP header. 56 * 57 * So, clearly good old protosw does not work for protocol #4 and #41. 58 * The code will let you match protocol via src/dst address pair. 59 */ 60 61 #include <sys/cdefs.h> 62 __FBSDID("$FreeBSD$"); 63 64 #include "opt_inet.h" 65 #include "opt_inet6.h" 66 67 #include <sys/param.h> 68 #include <sys/systm.h> 69 #include <sys/eventhandler.h> 70 #include <sys/kernel.h> 71 #include <sys/lock.h> 72 #include <sys/malloc.h> 73 #include <sys/mutex.h> 74 #include <sys/mbuf.h> 75 #include <sys/errno.h> 76 #include <sys/socket.h> 77 78 #include <net/if.h> 79 #include <net/if_var.h> 80 81 #include <netinet/in.h> 82 #include <netinet/ip_var.h> 83 #include <netinet/ip_encap.h> 84 85 #ifdef INET6 86 #include <netinet6/ip6_var.h> 87 #endif 88 89 static MALLOC_DEFINE(M_NETADDR, "encap_export_host", 90 "Export host address structure"); 91 92 struct encaptab { 93 CK_LIST_ENTRY(encaptab) chain; 94 int proto; 95 int min_length; 96 int exact_match; 97 void *arg; 98 99 encap_lookup_t lookup; 100 encap_check_t check; 101 encap_input_t input; 102 }; 103 104 struct srcaddrtab { 105 CK_LIST_ENTRY(srcaddrtab) chain; 106 107 encap_srcaddr_t srcaddr; 108 void *arg; 109 }; 110 111 CK_LIST_HEAD(encaptab_head, encaptab); 112 CK_LIST_HEAD(srcaddrtab_head, srcaddrtab); 113 #ifdef INET 114 static struct encaptab_head ipv4_encaptab = CK_LIST_HEAD_INITIALIZER(); 115 static struct srcaddrtab_head ipv4_srcaddrtab = CK_LIST_HEAD_INITIALIZER(); 116 #endif 117 #ifdef INET6 118 static struct encaptab_head ipv6_encaptab = CK_LIST_HEAD_INITIALIZER(); 119 static struct srcaddrtab_head ipv6_srcaddrtab = CK_LIST_HEAD_INITIALIZER(); 120 #endif 121 122 static struct mtx encapmtx, srcaddrmtx; 123 MTX_SYSINIT(encapmtx, &encapmtx, "encapmtx", MTX_DEF); 124 MTX_SYSINIT(srcaddrmtx, &srcaddrmtx, "srcaddrmtx", MTX_DEF); 125 #define ENCAP_WLOCK() mtx_lock(&encapmtx) 126 #define ENCAP_WUNLOCK() mtx_unlock(&encapmtx) 127 #define ENCAP_RLOCK_TRACKER struct epoch_tracker encap_et 128 #define ENCAP_RLOCK() \ 129 epoch_enter_preempt(net_epoch_preempt, &encap_et) 130 #define ENCAP_RUNLOCK() \ 131 epoch_exit_preempt(net_epoch_preempt, &encap_et) 132 #define ENCAP_WAIT() epoch_wait_preempt(net_epoch_preempt) 133 134 #define SRCADDR_WLOCK() mtx_lock(&srcaddrmtx) 135 #define SRCADDR_WUNLOCK() mtx_unlock(&srcaddrmtx) 136 #define SRCADDR_RLOCK_TRACKER struct epoch_tracker srcaddr_et 137 #define SRCADDR_RLOCK() \ 138 epoch_enter_preempt(net_epoch_preempt, &srcaddr_et) 139 #define SRCADDR_RUNLOCK() \ 140 epoch_exit_preempt(net_epoch_preempt, &srcaddr_et) 141 #define SRCADDR_WAIT() epoch_wait_preempt(net_epoch_preempt) 142 143 /* 144 * ifaddr_event_ext handler. 145 * 146 * Tunnelling interfaces may request the kernel to notify when 147 * some interface addresses appears or disappears. Usually tunnelling 148 * interface must use an address configured on the local machine as 149 * ingress address to be able receive datagramms and do not send 150 * spoofed packets. 151 */ 152 static void 153 srcaddr_change_event(void *arg __unused, struct ifnet *ifp, 154 struct ifaddr *ifa, int event) 155 { 156 SRCADDR_RLOCK_TRACKER; 157 struct srcaddrtab_head *head; 158 struct srcaddrtab *p; 159 160 /* Support for old ifaddr_event. */ 161 EVENTHANDLER_INVOKE(ifaddr_event, ifp); 162 163 switch (ifa->ifa_addr->sa_family) { 164 #ifdef INET 165 case AF_INET: 166 head = &ipv4_srcaddrtab; 167 break; 168 #endif 169 #ifdef INET6 170 case AF_INET6: 171 head = &ipv6_srcaddrtab; 172 break; 173 #endif 174 default: 175 /* ignore event */ 176 return; 177 } 178 179 SRCADDR_RLOCK(); 180 CK_LIST_FOREACH(p, head, chain) { 181 (*p->srcaddr)(p->arg, ifa->ifa_addr, event); 182 } 183 SRCADDR_RUNLOCK(); 184 } 185 EVENTHANDLER_DEFINE(ifaddr_event_ext, srcaddr_change_event, NULL, 0); 186 187 static struct srcaddrtab * 188 encap_register_srcaddr(struct srcaddrtab_head *head, encap_srcaddr_t func, 189 void *arg, int mflags) 190 { 191 struct srcaddrtab *p, *tmp; 192 193 if (func == NULL) 194 return (NULL); 195 p = malloc(sizeof(*p), M_NETADDR, mflags); 196 if (p == NULL) 197 return (NULL); 198 p->srcaddr = func; 199 p->arg = arg; 200 201 SRCADDR_WLOCK(); 202 CK_LIST_FOREACH(tmp, head, chain) { 203 if (func == tmp->srcaddr && arg == tmp->arg) 204 break; 205 } 206 if (tmp == NULL) 207 CK_LIST_INSERT_HEAD(head, p, chain); 208 SRCADDR_WUNLOCK(); 209 210 if (tmp != NULL) { 211 free(p, M_NETADDR); 212 p = tmp; 213 } 214 return (p); 215 } 216 217 static int 218 encap_unregister_srcaddr(struct srcaddrtab_head *head, 219 const struct srcaddrtab *cookie) 220 { 221 struct srcaddrtab *p; 222 223 SRCADDR_WLOCK(); 224 CK_LIST_FOREACH(p, head, chain) { 225 if (p == cookie) { 226 CK_LIST_REMOVE(p, chain); 227 SRCADDR_WUNLOCK(); 228 SRCADDR_WAIT(); 229 free(p, M_NETADDR); 230 return (0); 231 } 232 } 233 SRCADDR_WUNLOCK(); 234 return (EINVAL); 235 } 236 237 static struct encaptab * 238 encap_attach(struct encaptab_head *head, const struct encap_config *cfg, 239 void *arg, int mflags) 240 { 241 struct encaptab *ep, *tmp; 242 243 if (cfg == NULL || cfg->input == NULL || 244 (cfg->check == NULL && cfg->lookup == NULL) || 245 (cfg->lookup != NULL && cfg->exact_match != ENCAP_DRV_LOOKUP) || 246 (cfg->exact_match == ENCAP_DRV_LOOKUP && cfg->lookup == NULL)) 247 return (NULL); 248 249 ep = malloc(sizeof(*ep), M_NETADDR, mflags); 250 if (ep == NULL) 251 return (NULL); 252 253 ep->proto = cfg->proto; 254 ep->min_length = cfg->min_length; 255 ep->exact_match = cfg->exact_match; 256 ep->arg = arg; 257 ep->lookup = cfg->exact_match == ENCAP_DRV_LOOKUP ? cfg->lookup: NULL; 258 ep->check = cfg->exact_match != ENCAP_DRV_LOOKUP ? cfg->check: NULL; 259 ep->input = cfg->input; 260 261 ENCAP_WLOCK(); 262 CK_LIST_FOREACH(tmp, head, chain) { 263 if (tmp->exact_match <= ep->exact_match) 264 break; 265 } 266 if (tmp == NULL) 267 CK_LIST_INSERT_HEAD(head, ep, chain); 268 else 269 CK_LIST_INSERT_BEFORE(tmp, ep, chain); 270 ENCAP_WUNLOCK(); 271 return (ep); 272 } 273 274 static int 275 encap_detach(struct encaptab_head *head, const struct encaptab *cookie) 276 { 277 struct encaptab *ep; 278 279 ENCAP_WLOCK(); 280 CK_LIST_FOREACH(ep, head, chain) { 281 if (ep == cookie) { 282 CK_LIST_REMOVE(ep, chain); 283 ENCAP_WUNLOCK(); 284 ENCAP_WAIT(); 285 free(ep, M_NETADDR); 286 return (0); 287 } 288 } 289 ENCAP_WUNLOCK(); 290 return (EINVAL); 291 } 292 293 static int 294 encap_input(struct encaptab_head *head, struct mbuf *m, int off, int proto) 295 { 296 ENCAP_RLOCK_TRACKER; 297 struct encaptab *ep, *match; 298 void *arg; 299 int matchprio, ret; 300 301 match = NULL; 302 matchprio = 0; 303 304 ENCAP_RLOCK(); 305 CK_LIST_FOREACH(ep, head, chain) { 306 if (ep->proto >= 0 && ep->proto != proto) 307 continue; 308 if (ep->min_length > m->m_pkthdr.len) 309 continue; 310 if (ep->exact_match == ENCAP_DRV_LOOKUP) 311 ret = (*ep->lookup)(m, off, proto, &arg); 312 else 313 ret = (*ep->check)(m, off, proto, ep->arg); 314 if (ret <= 0) 315 continue; 316 if (ret > matchprio) { 317 match = ep; 318 if (ep->exact_match != ENCAP_DRV_LOOKUP) 319 arg = ep->arg; 320 /* 321 * No need to continue the search, we got the 322 * exact match. 323 */ 324 if (ret >= ep->exact_match) 325 break; 326 matchprio = ret; 327 } 328 } 329 330 if (match != NULL) { 331 /* found a match, "match" has the best one */ 332 ret = (*match->input)(m, off, proto, arg); 333 ENCAP_RUNLOCK(); 334 MPASS(ret == IPPROTO_DONE); 335 return (IPPROTO_DONE); 336 } 337 ENCAP_RUNLOCK(); 338 return (0); 339 } 340 341 #ifdef INET 342 const struct srcaddrtab * 343 ip_encap_register_srcaddr(encap_srcaddr_t func, void *arg, int mflags) 344 { 345 346 return (encap_register_srcaddr(&ipv4_srcaddrtab, func, arg, mflags)); 347 } 348 349 int 350 ip_encap_unregister_srcaddr(const struct srcaddrtab *cookie) 351 { 352 353 return (encap_unregister_srcaddr(&ipv4_srcaddrtab, cookie)); 354 } 355 356 const struct encaptab * 357 ip_encap_attach(const struct encap_config *cfg, void *arg, int mflags) 358 { 359 360 return (encap_attach(&ipv4_encaptab, cfg, arg, mflags)); 361 } 362 363 int 364 ip_encap_detach(const struct encaptab *cookie) 365 { 366 367 return (encap_detach(&ipv4_encaptab, cookie)); 368 } 369 370 int 371 encap4_input(struct mbuf **mp, int *offp, int proto) 372 { 373 374 if (encap_input(&ipv4_encaptab, *mp, *offp, proto) != IPPROTO_DONE) 375 return (rip_input(mp, offp, proto)); 376 return (IPPROTO_DONE); 377 } 378 #endif /* INET */ 379 380 #ifdef INET6 381 const struct srcaddrtab * 382 ip6_encap_register_srcaddr(encap_srcaddr_t func, void *arg, int mflags) 383 { 384 385 return (encap_register_srcaddr(&ipv6_srcaddrtab, func, arg, mflags)); 386 } 387 388 int 389 ip6_encap_unregister_srcaddr(const struct srcaddrtab *cookie) 390 { 391 392 return (encap_unregister_srcaddr(&ipv6_srcaddrtab, cookie)); 393 } 394 395 const struct encaptab * 396 ip6_encap_attach(const struct encap_config *cfg, void *arg, int mflags) 397 { 398 399 return (encap_attach(&ipv6_encaptab, cfg, arg, mflags)); 400 } 401 402 int 403 ip6_encap_detach(const struct encaptab *cookie) 404 { 405 406 return (encap_detach(&ipv6_encaptab, cookie)); 407 } 408 409 int 410 encap6_input(struct mbuf **mp, int *offp, int proto) 411 { 412 413 if (encap_input(&ipv6_encaptab, *mp, *offp, proto) != IPPROTO_DONE) 414 return (rip6_input(mp, offp, proto)); 415 return (IPPROTO_DONE); 416 } 417 #endif /* INET6 */ 418