1/*- 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30#include <sys/cdefs.h>
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78#endif 79#define V_ip4_ipsec_filtertunnel VNET(ip4_ipsec_filtertunnel) 80 81SYSCTL_DECL(_net_inet_ipsec); 82SYSCTL_VNET_INT(_net_inet_ipsec, OID_AUTO, filtertunnel, 83 CTLFLAG_RW, &VNET_NAME(ip4_ipsec_filtertunnel), 0, 84 "If set filter packets from an IPsec tunnel."); 85#endif /* IPSEC */ 86 87/* 88 * Check if we have to jump over firewall processing for this packet. 89 * Called from ip_input(). 90 * 1 = jump over firewall, 0 = packet goes through firewall. 91 */ 92int 93ip_ipsec_filtertunnel(struct mbuf *m) 94{ 95#if defined(IPSEC) 96 97 /* 98 * Bypass packet filtering for packets from a tunnel. 99 */ 100 if (!V_ip4_ipsec_filtertunnel && 101 m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL) 102 return 1; 103#endif 104 return 0; 105} 106 107/* 108 * Check if this packet has an active SA and needs to be dropped instead 109 * of forwarded. 110 * Called from ip_input(). 111 * 1 = drop packet, 0 = forward packet. 112 */ 113int 114ip_ipsec_fwd(struct mbuf *m) 115{ 116#ifdef IPSEC 117 struct m_tag *mtag; 118 struct tdb_ident *tdbi; 119 struct secpolicy *sp; 120 int s, error; 121 122 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); 123 s = splnet(); 124 if (mtag != NULL) { 125 tdbi = (struct tdb_ident *)(mtag + 1); 126 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND); 127 } else { 128 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND, 129 IP_FORWARDING, &error); 130 } 131 if (sp == NULL) { /* NB: can happen if error */ 132 splx(s); 133 /*XXX error stat???*/ 134 DPRINTF(("ip_input: no SP for forwarding\n")); /*XXX*/ 135 return 1; 136 } 137 138 /* 139 * Check security policy against packet attributes. 140 */ 141 error = ipsec_in_reject(sp, m); 142 KEY_FREESP(&sp); 143 splx(s); 144 if (error) { 145 IPSTAT_INC(ips_cantforward); 146 return 1; 147 } 148#endif /* IPSEC */ 149 return 0; 150} 151 152/* 153 * Check if protocol type doesn't have a further header and do IPSEC 154 * decryption or reject right now. Protocols with further headers get 155 * their IPSEC treatment within the protocol specific processing. 156 * Called from ip_input(). 157 * 1 = drop packet, 0 = continue processing packet. 158 */ 159int 160ip_ipsec_input(struct mbuf *m) 161{ 162#ifdef IPSEC 163 struct ip *ip = mtod(m, struct ip *); 164 struct m_tag *mtag; 165 struct tdb_ident *tdbi; 166 struct secpolicy *sp; 167 int s, error; 168 /* 169 * enforce IPsec policy checking if we are seeing last header. 170 * note that we do not visit this with protocols with pcb layer 171 * code - like udp/tcp/raw ip. 172 */ 173 if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) { 174 /* 175 * Check if the packet has already had IPsec processing 176 * done. If so, then just pass it along. This tag gets 177 * set during AH, ESP, etc. input handling, before the 178 * packet is returned to the ip input queue for delivery. 179 */ 180 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); 181 s = splnet(); 182 if (mtag != NULL) { 183 tdbi = (struct tdb_ident *)(mtag + 1); 184 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND); 185 } else { 186 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND, 187 IP_FORWARDING, &error); 188 } 189 if (sp != NULL) { 190 /* 191 * Check security policy against packet attributes. 192 */ 193 error = ipsec_in_reject(sp, m); 194 KEY_FREESP(&sp); 195 } else { 196 /* XXX error stat??? */ 197 error = EINVAL; 198 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/ 199 return 1; 200 } 201 splx(s); 202 if (error) 203 return 1; 204 } 205#endif /* IPSEC */ 206 return 0; 207} 208 209/* 210 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated. 211 * Called from ip_forward(). 212 * Returns MTU suggestion for ICMP needfrag reply. 213 */ 214int 215ip_ipsec_mtu(struct mbuf *m, int mtu) 216{ 217 /* 218 * If the packet is routed over IPsec tunnel, tell the 219 * originator the tunnel MTU. 220 * tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz 221 * XXX quickhack!!! 222 */ 223 struct secpolicy *sp = NULL; 224 int ipsecerror; 225 int ipsechdr; 226 struct route *ro; 227 sp = ipsec_getpolicybyaddr(m, 228 IPSEC_DIR_OUTBOUND, 229 IP_FORWARDING, 230 &ipsecerror); 231 if (sp != NULL) { 232 /* count IPsec header size */ 233 ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL); 234 235 /* 236 * find the correct route for outer IPv4 237 * header, compute tunnel MTU. 238 */ 239 if (sp->req != NULL && 240 sp->req->sav != NULL && 241 sp->req->sav->sah != NULL) { 242 ro = &sp->req->sav->sah->route_cache.sa_route; 243 if (ro->ro_rt && ro->ro_rt->rt_ifp) { 244 mtu = 245 ro->ro_rt->rt_rmx.rmx_mtu ? 246 ro->ro_rt->rt_rmx.rmx_mtu : 247 ro->ro_rt->rt_ifp->if_mtu; 248 mtu -= ipsechdr; 249 } 250 } 251 KEY_FREESP(&sp); 252 } 253 return mtu; 254} 255 256/* 257 * 258 * Called from ip_output(). 259 * 1 = drop packet, 0 = continue processing packet, 260 * -1 = packet was reinjected and stop processing packet 261 */ 262int 263ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error) 264{ 265#ifdef IPSEC 266 struct secpolicy *sp = NULL; 267 struct ip *ip = mtod(*m, struct ip *); 268 struct tdb_ident *tdbi; 269 struct m_tag *mtag; 270 int s; 271 /* 272 * Check the security policy (SP) for the packet and, if 273 * required, do IPsec-related processing. There are two 274 * cases here; the first time a packet is sent through 275 * it will be untagged and handled by ipsec4_checkpolicy. 276 * If the packet is resubmitted to ip_output (e.g. after 277 * AH, ESP, etc. processing), there will be a tag to bypass 278 * the lookup and related policy checking. 279 */ 280 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL); 281 s = splnet(); 282 if (mtag != NULL) { 283 tdbi = (struct tdb_ident *)(mtag + 1); 284 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND); 285 if (sp == NULL) 286 *error = -EINVAL; /* force silent drop */ 287 m_tag_delete(*m, mtag); 288 } else { 289 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags, 290 error, inp); 291 } 292 /* 293 * There are four return cases: 294 * sp != NULL apply IPsec policy 295 * sp == NULL, error == 0 no IPsec handling needed 296 * sp == NULL, error == -EINVAL discard packet w/o error 297 * sp == NULL, error != 0 discard packet, report error 298 */ 299 if (sp != NULL) { 300 /* Loop detection, check if ipsec processing already done */ 301 KASSERT(sp->req != NULL, ("ip_output: no ipsec request")); 302 for (mtag = m_tag_first(*m); mtag != NULL; 303 mtag = m_tag_next(*m, mtag)) { 304 if (mtag->m_tag_cookie != MTAG_ABI_COMPAT) 305 continue; 306 if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE && 307 mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED) 308 continue; 309 /* 310 * Check if policy has an SA associated with it. 311 * This can happen when an SP has yet to acquire 312 * an SA; e.g. on first reference. If it occurs, 313 * then we let ipsec4_process_packet do its thing. 314 */ 315 if (sp->req->sav == NULL) 316 break; 317 tdbi = (struct tdb_ident *)(mtag + 1); 318 if (tdbi->spi == sp->req->sav->spi && 319 tdbi->proto == sp->req->sav->sah->saidx.proto && 320 bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst, 321 sizeof (union sockaddr_union)) == 0) { 322 /* 323 * No IPsec processing is needed, free 324 * reference to SP. 325 * 326 * NB: null pointer to avoid free at 327 * done: below. 328 */ 329 KEY_FREESP(&sp), sp = NULL; 330 splx(s); 331 goto done; 332 } 333 } 334 335 /* 336 * Do delayed checksums now because we send before 337 * this is done in the normal processing path. 338 */ 339 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) { 340 in_delayed_cksum(*m); 341 (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA; 342 } 343#ifdef SCTP 344 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP) { 345 sctp_delayed_cksum(*m, (uint32_t)(ip->ip_hl << 2)); 346 (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP; 347 } 348#endif 349 ip->ip_len = htons(ip->ip_len); 350 ip->ip_off = htons(ip->ip_off); 351 352 /* NB: callee frees mbuf */ 353 *error = ipsec4_process_packet(*m, sp->req, *flags, 0); 354 if (*error == EJUSTRETURN) { 355 /* 356 * We had a SP with a level of 'use' and no SA. We 357 * will just continue to process the packet without 358 * IPsec processing and return without error. 359 */ 360 *error = 0; 361 ip->ip_len = ntohs(ip->ip_len); 362 ip->ip_off = ntohs(ip->ip_off); 363 goto done; 364 } 365 /* 366 * Preserve KAME behaviour: ENOENT can be returned 367 * when an SA acquire is in progress. Don't propagate 368 * this to user-level; it confuses applications. 369 * 370 * XXX this will go away when the SADB is redone. 371 */ 372 if (*error == ENOENT) 373 *error = 0; 374 splx(s); 375 goto reinjected; 376 } else { /* sp == NULL */ 377 splx(s); 378 379 if (*error != 0) { 380 /* 381 * Hack: -EINVAL is used to signal that a packet 382 * should be silently discarded. This is typically 383 * because we asked key management for an SA and 384 * it was delayed (e.g. kicked up to IKE). 385 */ 386 if (*error == -EINVAL) 387 *error = 0; 388 goto bad; 389 } else { 390 /* No IPsec processing for this packet. */ 391 } 392 } 393done: 394 if (sp != NULL) 395 KEY_FREESP(&sp); 396 return 0; 397reinjected: 398 if (sp != NULL) 399 KEY_FREESP(&sp); 400 return -1; 401bad: 402 if (sp != NULL) 403 KEY_FREESP(&sp); 404 return 1; 405#endif /* IPSEC */ 406 return 0; 407}
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