1 /* $NetBSD: in_l2tp.c,v 1.22 2023/09/01 11:23:39 andvar 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: in_l2tp.c,v 1.22 2023/09/01 11:23:39 andvar 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 #include <sys/socketvar.h> /* For softnet_lock */ 46 47 #include <net/if.h> 48 #include <net/route.h> 49 #include <net/if_ether.h> 50 51 #include <netinet/in.h> 52 #include <netinet/in_systm.h> 53 #include <netinet/ip.h> 54 #include <netinet/ip_var.h> 55 #include <netinet/ip_private.h> 56 #include <netinet/in_l2tp.h> 57 #include <netinet/in_var.h> 58 #include <netinet/ip_encap.h> 59 60 #ifdef ALTQ 61 #include <altq/altq.h> 62 #endif 63 64 /* TODO: IP_TCPMSS support */ 65 #undef IP_TCPMSS 66 #ifdef IP_TCPMSS 67 #include <netinet/ip_tcpmss.h> 68 #endif 69 70 #include <net/if_l2tp.h> 71 72 int ip_l2tp_ttl = L2TP_TTL; 73 74 static void in_l2tp_input(struct mbuf *, int, int, void *); 75 76 static const struct encapsw in_l2tp_encapsw = { 77 .encapsw4 = { 78 .pr_input = in_l2tp_input, 79 .pr_ctlinput = NULL, 80 } 81 }; 82 83 static int in_l2tp_match(struct mbuf *, int, int, void *); 84 85 int 86 in_l2tp_output(struct l2tp_variant *var, struct mbuf *m) 87 { 88 struct l2tp_softc *sc; 89 struct ifnet *ifp; 90 struct sockaddr_in *sin_src = satosin(var->lv_psrc); 91 struct sockaddr_in *sin_dst = satosin(var->lv_pdst); 92 struct ip iphdr; /* capsule IP header, host byte ordered */ 93 struct rtentry *rt; 94 struct route *ro_pc; 95 kmutex_t *lock_pc; 96 97 int error; 98 uint32_t sess_id; 99 100 KASSERT(var != NULL); 101 KASSERT(l2tp_heldref_variant(var)); 102 KASSERT(sin_src != NULL && sin_dst != NULL); 103 KASSERT(sin_src->sin_family == AF_INET 104 && sin_dst->sin_family == AF_INET); 105 106 sc = var->lv_softc; 107 ifp = &sc->l2tp_ec.ec_if; 108 error = l2tp_check_nesting(ifp, m); 109 if (error) { 110 m_freem(m); 111 goto looped; 112 } 113 114 /* bidirectional configured tunnel mode */ 115 if (sin_dst->sin_addr.s_addr == INADDR_ANY) { 116 m_freem(m); 117 if ((ifp->if_flags & IFF_DEBUG) != 0) 118 log(LOG_DEBUG, "%s: ENETUNREACH\n", __func__); 119 error = ENETUNREACH; 120 goto out; 121 } 122 123 #ifdef NOTYET 124 /* TODO: support ALTQ for inner frame */ 125 #ifdef ALTQ 126 ALTQ_SAVE_PAYLOAD(m, AF_ETHER); 127 #endif 128 #endif 129 130 memset(&iphdr, 0, sizeof(iphdr)); 131 iphdr.ip_src = sin_src->sin_addr; 132 iphdr.ip_dst = sin_dst->sin_addr; 133 iphdr.ip_p = IPPROTO_L2TP; 134 /* version will be set in ip_output() */ 135 iphdr.ip_ttl = ip_l2tp_ttl; 136 /* outer IP header length */ 137 iphdr.ip_len = sizeof(struct ip); 138 /* session-id length */ 139 iphdr.ip_len += sizeof(uint32_t); 140 if (var->lv_use_cookie == L2TP_COOKIE_ON) { 141 /* cookie length */ 142 iphdr.ip_len += var->lv_peer_cookie_len; 143 } 144 145 /* TODO: IP_TCPMSS support */ 146 #ifdef IP_TCPMSS 147 m = l2tp_tcpmss_clamp(ifp, m); 148 if (m == NULL) { 149 error = EINVAL; 150 goto out; 151 } 152 #endif 153 154 /* 155 * Payload length. 156 * 157 * NOTE: payload length may be changed in ip_tcpmss(). Typical case 158 * is missing of TCP mss option in original TCP header. 159 */ 160 iphdr.ip_len += m->m_pkthdr.len; 161 HTONS(iphdr.ip_len); 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 error = ENOBUFS; 172 goto out; 173 } 174 if (var->lv_peer_cookie_len == 4) { 175 cookie_32 = htonl((uint32_t)var->lv_peer_cookie); 176 memcpy(mtod(m, void *), &cookie_32, sizeof(uint32_t)); 177 } else { 178 cookie_64 = htobe64(var->lv_peer_cookie); 179 memcpy(mtod(m, void *), &cookie_64, 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 error = ENOBUFS; 190 goto out; 191 } 192 memcpy(mtod(m, uint32_t *), &sess_id, sizeof(uint32_t)); 193 194 /* prepend new IP header */ 195 M_PREPEND(m, sizeof(struct ip), M_DONTWAIT); 196 if (m == NULL) { 197 error = ENOBUFS; 198 goto out; 199 } 200 if (M_GET_ALIGNED_HDR(&m, struct ip, false) != 0) { 201 error = ENOBUFS; 202 goto out; 203 } 204 memcpy(mtod(m, struct ip *), &iphdr, sizeof(struct ip)); 205 206 if_tunnel_get_ro(sc->l2tp_ro_percpu, &ro_pc, &lock_pc); 207 if ((rt = rtcache_lookup(ro_pc, var->lv_pdst)) == NULL) { 208 if_tunnel_put_ro(sc->l2tp_ro_percpu, lock_pc); 209 m_freem(m); 210 error = ENETUNREACH; 211 goto out; 212 } 213 214 if (rt->rt_ifp == ifp) { 215 rtcache_unref(rt, ro_pc); 216 rtcache_free(ro_pc); 217 if_tunnel_put_ro(sc->l2tp_ro_percpu, lock_pc); 218 m_freem(m); 219 error = ENETUNREACH; /*XXX*/ 220 goto out; 221 } 222 rtcache_unref(rt, ro_pc); 223 224 /* 225 * To avoid inappropriate rewrite of checksum, 226 * clear csum flags. 227 */ 228 m->m_pkthdr.csum_flags = 0; 229 230 error = ip_output(m, NULL, ro_pc, 0, NULL, NULL); 231 if_tunnel_put_ro(sc->l2tp_ro_percpu, lock_pc); 232 return error; 233 234 looped: 235 if (error) 236 if_statinc(ifp, if_oerrors); 237 238 out: 239 return error; 240 } 241 242 static void 243 in_l2tp_input(struct mbuf *m, int off, int proto, void *eparg __unused) 244 { 245 struct ifnet *l2tpp = NULL; 246 struct l2tp_softc *sc; 247 uint32_t sess_id; 248 uint32_t cookie_32; 249 uint64_t cookie_64; 250 struct psref psref; 251 struct l2tp_variant *var; 252 253 KASSERT((m->m_flags & M_PKTHDR) != 0); 254 255 if (m->m_pkthdr.len < off + sizeof(uint32_t)) { 256 m_freem(m); 257 return; 258 } 259 260 /* get L2TP session ID */ 261 m_copydata(m, off, sizeof(uint32_t), (void *)&sess_id); 262 NTOHL(sess_id); 263 #ifdef L2TP_DEBUG 264 log(LOG_DEBUG, "%s: sess_id = %" PRIu32 "\n", __func__, sess_id); 265 #endif 266 if (sess_id == 0) { 267 /* 268 * L2TPv3 control packet received. 269 * userland daemon(l2tpd?) should process. 270 */ 271 SOFTNET_LOCK_IF_NET_MPSAFE(); 272 rip_input(m, off, proto); 273 SOFTNET_UNLOCK_IF_NET_MPSAFE(); 274 return; 275 } 276 277 var = l2tp_lookup_session_ref(sess_id, &psref); 278 if (var == NULL) { 279 m_freem(m); 280 ip_statinc(IP_STAT_NOL2TP); 281 return; 282 } 283 284 sc = var->lv_softc; 285 l2tpp = &(sc->l2tp_ec.ec_if); 286 287 if (l2tpp == NULL || (l2tpp->if_flags & IFF_UP) == 0) { 288 #ifdef L2TP_DEBUG 289 if (l2tpp == NULL) 290 log(LOG_DEBUG, "%s: l2tpp is NULL\n", __func__); 291 else 292 log(LOG_DEBUG, "%s: l2tpp is down\n", __func__); 293 #endif 294 m_freem(m); 295 ip_statinc(IP_STAT_NOL2TP); 296 goto out; 297 } 298 299 /* other CPU did l2tp_delete_tunnel */ 300 if (var->lv_psrc == NULL || var->lv_pdst == NULL) { 301 m_freem(m); 302 ip_statinc(IP_STAT_NOL2TP); 303 goto out; 304 } 305 306 if (var->lv_state != L2TP_STATE_UP) { 307 m_freem(m); 308 goto out; 309 } 310 311 m_adj(m, off + sizeof(uint32_t)); 312 313 if (var->lv_use_cookie == L2TP_COOKIE_ON) { 314 if (m->m_pkthdr.len < var->lv_my_cookie_len) { 315 m_freem(m); 316 goto out; 317 } 318 if (var->lv_my_cookie_len == 4) { 319 m_copydata(m, 0, sizeof(uint32_t), (void *)&cookie_32); 320 NTOHL(cookie_32); 321 if (cookie_32 != var->lv_my_cookie) { 322 m_freem(m); 323 goto out; 324 } 325 m_adj(m, sizeof(uint32_t)); 326 } else { 327 m_copydata(m, 0, sizeof(uint64_t), (void *)&cookie_64); 328 BE64TOH(cookie_64); 329 if (cookie_64 != var->lv_my_cookie) { 330 m_freem(m); 331 goto out; 332 } 333 m_adj(m, sizeof(uint64_t)); 334 } 335 } 336 337 /* TODO: IP_TCPMSS support */ 338 #ifdef IP_TCPMSS 339 m = l2tp_tcpmss_clamp(l2tpp, m); 340 if (m == NULL) 341 goto out; 342 #endif 343 l2tp_input(m, l2tpp); 344 345 out: 346 l2tp_putref_variant(var, &psref); 347 return; 348 } 349 350 /* 351 * This function is used by encap4_lookup() to decide priority of the encaptab. 352 * This priority is compared to the match length between mbuf's source/destination 353 * IPv4 address pair and encaptab's one. 354 * l2tp(4) does not use address pairs to search matched encaptab, so this 355 * function must return the length bigger than or equals to IPv4 address pair to 356 * avoid wrong encaptab. 357 */ 358 static int 359 in_l2tp_match(struct mbuf *m, int off, int proto, void *arg) 360 { 361 struct l2tp_softc *sc = arg; 362 struct l2tp_variant *var; 363 struct psref psref; 364 uint32_t sess_id; 365 int rv = 0; 366 367 KASSERT(proto == IPPROTO_L2TP); 368 369 var = l2tp_getref_variant(sc, &psref); 370 if (__predict_false(var == NULL)) 371 return rv; 372 373 /* 374 * If the packet contains no session ID it cannot match 375 */ 376 if (m_length(m) < off + sizeof(uint32_t)) { 377 rv = 0; 378 goto out; 379 } 380 381 /* get L2TP session ID */ 382 m_copydata(m, off, sizeof(uint32_t), (void *)&sess_id); 383 NTOHL(sess_id); 384 if (sess_id == 0) { 385 /* 386 * L2TPv3 control packet received. 387 * userland daemon(l2tpd?) should process. 388 */ 389 rv = 32 * 2; 390 } else if (sess_id == var->lv_my_sess_id) 391 rv = 32 * 2; 392 else 393 rv = 0; 394 395 out: 396 l2tp_putref_variant(var, &psref); 397 return rv; 398 } 399 400 int 401 in_l2tp_attach(struct l2tp_variant *var) 402 { 403 struct l2tp_softc *sc = var->lv_softc; 404 405 if (sc == NULL) 406 return EINVAL; 407 408 var->lv_encap_cookie = encap_attach_addr(AF_INET, IPPROTO_L2TP, 409 var->lv_psrc, var->lv_pdst, in_l2tp_match, &in_l2tp_encapsw, sc); 410 if (var->lv_encap_cookie == NULL) 411 return EEXIST; 412 413 return 0; 414 } 415 416 int 417 in_l2tp_detach(struct l2tp_variant *var) 418 { 419 int error; 420 421 error = encap_detach(var->lv_encap_cookie); 422 if (error == 0) 423 var->lv_encap_cookie = NULL; 424 425 return error; 426 } 427
Indexes created Tue Sep 23 23:09:58 GMT 2025