in6_l2tp.c revision 1.12
1 /* $NetBSD: in6_l2tp.c,v 1.12 2017/12/18 03:21:44 knakahara Exp $ */ 2 3 /* 4 * Copyright (c) 2017 Internet Initiative Japan Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __KERNEL_RCSID(0, "$NetBSD: in6_l2tp.c,v 1.12 2017/12/18 03:21:44 knakahara Exp $"); 31 32 #ifdef _KERNEL_OPT 33 #include "opt_l2tp.h" 34 #endif 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/socket.h> 39 #include <sys/sockio.h> 40 #include <sys/mbuf.h> 41 #include <sys/errno.h> 42 #include <sys/ioctl.h> 43 #include <sys/syslog.h> 44 #include <sys/kernel.h> 45 46 #include <net/if.h> 47 #include <net/route.h> 48 #include <net/if_ether.h> 49 50 #include <netinet/in.h> 51 #include <netinet/in_systm.h> 52 #include <netinet/ip.h> 53 #include <netinet/ip_var.h> 54 #include <netinet/ip_private.h> 55 #include <netinet/in_l2tp.h> 56 #include <netinet/in_var.h> 57 #include <netinet/ip_encap.h> 58 59 #include <netinet/ip6.h> 60 #include <netinet6/ip6_var.h> 61 #include <netinet6/in6_l2tp.h> 62 63 #ifdef ALTQ 64 #include <altq/altq.h> 65 #endif 66 67 /* TODO: IP_TCPMSS support */ 68 #undef IP_TCPMSS 69 #ifdef IP_TCPMSS 70 #include <netinet/ip_tcpmss.h> 71 #endif 72 73 #include <net/if_l2tp.h> 74 75 #define L2TP_HLIM6 64 76 int ip6_l2tp_hlim = L2TP_HLIM6; 77 78 static int in6_l2tp_input(struct mbuf **, int *, int, void *); 79 80 static const struct encapsw in6_l2tp_encapsw = { 81 .encapsw6 = { 82 .pr_input = in6_l2tp_input, 83 .pr_ctlinput = NULL, 84 } 85 }; 86 87 static int in6_l2tp_match(struct mbuf *, int, int, void *); 88 89 int 90 in6_l2tp_output(struct l2tp_variant *var, struct mbuf *m) 91 { 92 struct rtentry *rt; 93 struct l2tp_ro *lro; 94 struct l2tp_softc *sc; 95 struct ifnet *ifp; 96 struct sockaddr_in6 *sin6_src = satosin6(var->lv_psrc); 97 struct sockaddr_in6 *sin6_dst = satosin6(var->lv_pdst); 98 struct ip6_hdr ip6hdr; /* capsule IP header, host byte ordered */ 99 int error; 100 uint32_t sess_id; 101 102 KASSERT(var != NULL); 103 KASSERT(l2tp_heldref_variant(var)); 104 KASSERT(sin6_src != NULL && sin6_dst != NULL); 105 KASSERT(sin6_src->sin6_family == AF_INET6 106 && sin6_dst->sin6_family == AF_INET6); 107 108 sc = var->lv_softc; 109 ifp = &sc->l2tp_ec.ec_if; 110 error = l2tp_check_nesting(ifp, m); 111 if (error) { 112 m_freem(m); 113 goto looped; 114 } 115 116 #ifdef NOTYET 117 /* TODO: support ALTQ for innner frame */ 118 #ifdef ALTQ 119 ALTQ_SAVE_PAYLOAD(m, AF_ETHER); 120 #endif 121 #endif 122 123 memset(&ip6hdr, 0, sizeof(ip6hdr)); 124 ip6hdr.ip6_src = sin6_src->sin6_addr; 125 /* bidirectional configured tunnel mode */ 126 if (!IN6_IS_ADDR_UNSPECIFIED(&sin6_dst->sin6_addr)) 127 ip6hdr.ip6_dst = sin6_dst->sin6_addr; 128 else { 129 m_freem(m); 130 if ((ifp->if_flags & IFF_DEBUG) != 0) 131 log(LOG_DEBUG, "%s: ENETUNREACH\n", __func__); 132 return ENETUNREACH; 133 } 134 /* unlike IPv4, IP version must be filled by caller of ip6_output() */ 135 ip6hdr.ip6_vfc = 0x60; 136 ip6hdr.ip6_nxt = IPPROTO_L2TP; 137 ip6hdr.ip6_hlim = ip6_l2tp_hlim; 138 /* outer IP payload length */ 139 ip6hdr.ip6_plen = 0; 140 /* session-id length */ 141 ip6hdr.ip6_plen += sizeof(uint32_t); 142 if (var->lv_use_cookie == L2TP_COOKIE_ON) { 143 /* cookie length */ 144 ip6hdr.ip6_plen += var->lv_peer_cookie_len; 145 } 146 147 /* TODO: IP_TCPMSS support */ 148 #ifdef IP_TCPMSS 149 m = l2tp_tcpmss_clamp(ifp, m); 150 if (m == NULL) 151 return EINVAL; 152 #endif 153 154 /* 155 * payload length 156 * NOTE: Payload length may be changed in ip_tcpmss(). 157 * Typical case is missing of TCP mss option in original 158 * TCP header. 159 */ 160 ip6hdr.ip6_plen += m->m_pkthdr.len; 161 HTONS(ip6hdr.ip6_plen); 162 163 if (var->lv_use_cookie == L2TP_COOKIE_ON) { 164 /* prepend session cookie */ 165 uint32_t cookie_32; 166 uint64_t cookie_64; 167 M_PREPEND(m, var->lv_peer_cookie_len, M_DONTWAIT); 168 if (m && m->m_len < var->lv_peer_cookie_len) 169 m = m_pullup(m, var->lv_peer_cookie_len); 170 if (m == NULL) 171 return ENOBUFS; 172 if (var->lv_peer_cookie_len == 4) { 173 cookie_32 = htonl((uint32_t)var->lv_peer_cookie); 174 memcpy(mtod(m, void *), &cookie_32, 175 sizeof(uint32_t)); 176 } else { 177 cookie_64 = htobe64(var->lv_peer_cookie); 178 memcpy(mtod(m, void *), &cookie_64, 179 sizeof(uint64_t)); 180 } 181 } 182 183 /* prepend session-ID */ 184 sess_id = htonl(var->lv_peer_sess_id); 185 M_PREPEND(m, sizeof(uint32_t), M_DONTWAIT); 186 if (m && m->m_len < sizeof(uint32_t)) 187 m = m_pullup(m, sizeof(uint32_t)); 188 if (m == NULL) 189 return ENOBUFS; 190 memcpy(mtod(m, uint32_t *), &sess_id, sizeof(uint32_t)); 191 192 /* prepend new IP header */ 193 M_PREPEND(m, sizeof(struct ip6_hdr), M_DONTWAIT); 194 if (IP_HDR_ALIGNED_P(mtod(m, void *)) == 0) { 195 if (m) 196 m = m_copyup(m, sizeof(struct ip), 0); 197 } else { 198 if (m && m->m_len < sizeof(struct ip6_hdr)) 199 m = m_pullup(m, sizeof(struct ip6_hdr)); 200 } 201 if (m == NULL) 202 return ENOBUFS; 203 memcpy(mtod(m, struct ip6_hdr *), &ip6hdr, sizeof(struct ip6_hdr)); 204 205 lro = percpu_getref(sc->l2tp_ro_percpu); 206 mutex_enter(&lro->lr_lock); 207 if ((rt = rtcache_lookup(&lro->lr_ro, var->lv_pdst)) == NULL) { 208 mutex_exit(&lro->lr_lock); 209 percpu_putref(sc->l2tp_ro_percpu); 210 m_freem(m); 211 return ENETUNREACH; 212 } 213 214 /* If the route constitutes infinite encapsulation, punt. */ 215 if (rt->rt_ifp == ifp) { 216 rtcache_unref(rt, &lro->lr_ro); 217 rtcache_free(&lro->lr_ro); 218 mutex_exit(&lro->lr_lock); 219 percpu_putref(sc->l2tp_ro_percpu); 220 m_freem(m); 221 return ENETUNREACH; /* XXX */ 222 } 223 rtcache_unref(rt, &lro->lr_ro); 224 225 /* 226 * To avoid inappropriate rewrite of checksum, 227 * clear csum flags. 228 */ 229 m->m_pkthdr.csum_flags = 0; 230 231 error = ip6_output(m, 0, &lro->lr_ro, 0, NULL, NULL, NULL); 232 mutex_exit(&lro->lr_lock); 233 percpu_putref(sc->l2tp_ro_percpu); 234 return(error); 235 236 looped: 237 if (error) 238 ifp->if_oerrors++; 239 240 return error; 241 } 242 243 static int 244 in6_l2tp_input(struct mbuf **mp, int *offp, int proto, void *eparg __unused) 245 { 246 struct mbuf *m = *mp; 247 int off = *offp; 248 249 struct ifnet *l2tpp = NULL; 250 struct l2tp_softc *sc; 251 struct l2tp_variant *var; 252 uint32_t sess_id; 253 uint32_t cookie_32; 254 uint64_t cookie_64; 255 struct psref psref; 256 257 if (m->m_len < off + sizeof(uint32_t)) { 258 m = m_pullup(m, off + sizeof(uint32_t)); 259 if (!m) { 260 /* if payload length < 4 octets */ 261 return IPPROTO_DONE; 262 } 263 *mp = m; 264 } 265 266 /* get L2TP session ID */ 267 m_copydata(m, off, sizeof(uint32_t), (void *)&sess_id); 268 NTOHL(sess_id); 269 #ifdef L2TP_DEBUG 270 log(LOG_DEBUG, "%s: sess_id = %" PRIu32 "\n", __func__, sess_id); 271 #endif 272 if (sess_id == 0) { 273 /* 274 * L2TPv3 control packet received. 275 * userland daemon(l2tpd?) should process. 276 */ 277 return rip6_input(mp, offp, proto); 278 } 279 280 var = l2tp_lookup_session_ref(sess_id, &psref); 281 if (var == NULL) { 282 m_freem(m); 283 IP_STATINC(IP_STAT_NOL2TP); 284 return IPPROTO_DONE; 285 } else { 286 sc = var->lv_softc; 287 l2tpp = &(sc->l2tp_ec.ec_if); 288 289 if (l2tpp == NULL || (l2tpp->if_flags & IFF_UP) == 0) { 290 #ifdef L2TP_DEBUG 291 if (l2tpp == NULL) 292 log(LOG_DEBUG, "%s: l2tpp is NULL\n", __func__); 293 else 294 log(LOG_DEBUG, "%s: l2tpp is down\n", __func__); 295 #endif 296 m_freem(m); 297 IP_STATINC(IP_STAT_NOL2TP); 298 goto out; 299 } 300 /* other CPU do l2tp_delete_tunnel */ 301 if (var->lv_psrc == NULL || var->lv_pdst == NULL) { 302 m_freem(m); 303 ip_statinc(IP_STAT_NOL2TP); 304 goto out; 305 } 306 } 307 308 if (var->lv_state != L2TP_STATE_UP) { 309 m_freem(m); 310 goto out; 311 } 312 m_adj(m, off + sizeof(uint32_t)); 313 314 if (var->lv_use_cookie == L2TP_COOKIE_ON) { 315 if (var->lv_my_cookie_len == 4) { 316 m_copydata(m, 0, sizeof(uint32_t), (void *)&cookie_32); 317 NTOHL(cookie_32); 318 if (cookie_32 != var->lv_my_cookie) { 319 m_freem(m); 320 goto out; 321 } 322 m_adj(m, sizeof(uint32_t)); 323 } else { 324 m_copydata(m, 0, sizeof(uint64_t), (void *)&cookie_64); 325 BE64TOH(cookie_64); 326 if (cookie_64 != var->lv_my_cookie) { 327 m_freem(m); 328 goto out; 329 } 330 m_adj(m, sizeof(uint64_t)); 331 } 332 } 333 334 /* TODO: IP_TCPMSS support */ 335 #ifdef IP_TCPMSS 336 m = l2tp_tcpmss_clamp(l2tpp, m); 337 if (m == NULL) 338 goto out; 339 #endif 340 l2tp_input(m, l2tpp); 341 342 out: 343 l2tp_putref_variant(var, &psref); 344 return IPPROTO_DONE; 345 } 346 347 /* 348 * This function is used by encap6_lookup() to decide priority of the encaptab. 349 * This priority is compared to the match length between mbuf's source/destination 350 * IPv6 address pair and encaptab's one. 351 * l2tp(4) does not use address pairs to search matched encaptab, so this 352 * function must return the length bigger than or equals to IPv6 address pair to 353 * avoid wrong encaptab. 354 */ 355 static int 356 in6_l2tp_match(struct mbuf *m, int off, int proto, void *arg) 357 { 358 struct l2tp_variant *var = arg; 359 uint32_t sess_id; 360 361 KASSERT(proto == IPPROTO_L2TP); 362 363 /* 364 * If the packet contains no session ID it cannot match 365 */ 366 if (m_length(m) < off + sizeof(uint32_t)) 367 return 0; 368 369 /* get L2TP session ID */ 370 m_copydata(m, off, sizeof(uint32_t), (void *)&sess_id); 371 NTOHL(sess_id); 372 if (sess_id == 0) { 373 /* 374 * L2TPv3 control packet received. 375 * userland daemon(l2tpd?) should process. 376 */ 377 return 128 * 2; 378 } else if (sess_id == var->lv_my_sess_id) 379 return 128 * 2; 380 else 381 return 0; 382 } 383 384 int 385 in6_l2tp_attach(struct l2tp_variant *var) 386 { 387 388 var->lv_encap_cookie = encap_attach_func(AF_INET6, IPPROTO_L2TP, 389 in6_l2tp_match, &in6_l2tp_encapsw, var); 390 if (var->lv_encap_cookie == NULL) 391 return EEXIST; 392 393 return 0; 394 } 395 396 int 397 in6_l2tp_detach(struct l2tp_variant *var) 398 { 399 int error; 400 401 error = encap_detach(var->lv_encap_cookie); 402 if (error == 0) 403 var->lv_encap_cookie = NULL; 404 405 return error; 406 } 407
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