Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_ipsec.c
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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> 31 __FBSDID("$FreeBSD$"); 32 33 #include "opt_ipsec.h" 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/kernel.h> 38 #include <sys/malloc.h> 39 #include <sys/mbuf.h> 40 #include <sys/protosw.h> 41 #include <sys/socket.h> 42 #include <sys/socketvar.h> 43 #include <sys/sysctl.h> 44 45 #include <net/if.h> 46 #include <net/route.h> 47 48 #include <netinet/in.h> 49 #include <netinet/in_systm.h> 50 #include <netinet/in_var.h> 51 #include <netinet/ip.h> 52 #include <netinet/in_pcb.h> 53 #include <netinet/ip_var.h> 54 #include <netinet/ip_options.h> 55 #include <netinet/ip_ipsec.h> 56 57 #include <machine/in_cksum.h> 58 59 #ifdef IPSEC 60 #include <netipsec/ipsec.h> 61 #include <netipsec/xform.h> 62 #include <netipsec/key.h> 63 #endif /*IPSEC*/ 64 65 extern struct protosw inetsw[]; 66 67 /* 68 * Check if we have to jump over firewall processing for this packet. 69 * Called from ip_input(). 70 * 1 = jump over firewall, 0 = packet goes through firewall. 71 */ 72 int 73 ip_ipsec_filtertunnel(struct mbuf *m) 74 { 75 #if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL) 76 /* 77 * Bypass packet filtering for packets from a tunnel. 78 */ 79 if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL) 80 return 1; 81 #endif 82 return 0; 83 } 84 85 /* 86 * Check if this packet has an active SA and needs to be dropped instead 87 * of forwarded. 88 * Called from ip_input(). 89 * 1 = drop packet, 0 = forward packet. 90 */ 91 int 92 ip_ipsec_fwd(struct mbuf *m) 93 { 94 #ifdef IPSEC 95 struct m_tag *mtag; 96 struct tdb_ident *tdbi; 97 struct secpolicy *sp; 98 int s, error; 99 100 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); 101 s = splnet(); 102 if (mtag != NULL) { 103 tdbi = (struct tdb_ident *)(mtag + 1); 104 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND); 105 } else { 106 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND, 107 IP_FORWARDING, &error); 108 } 109 if (sp == NULL) { /* NB: can happen if error */ 110 splx(s); 111 /*XXX error stat???*/ 112 DPRINTF(("ip_input: no SP for forwarding\n")); /*XXX*/ 113 return 1; 114 } 115 116 /* 117 * Check security policy against packet attributes. 118 */ 119 error = ipsec_in_reject(sp, m); 120 KEY_FREESP(&sp); 121 splx(s); 122 if (error) { 123 ipstat.ips_cantforward++; 124 return 1; 125 } 126 #endif /* IPSEC */ 127 return 0; 128 } 129 130 /* 131 * Check if protocol type doesn't have a further header and do IPSEC 132 * decryption or reject right now. Protocols with further headers get 133 * their IPSEC treatment within the protocol specific processing. 134 * Called from ip_input(). 135 * 1 = drop packet, 0 = continue processing packet. 136 */ 137 int 138 ip_ipsec_input(struct mbuf *m) 139 { 140 struct ip *ip = mtod(m, struct ip *); 141 #ifdef IPSEC 142 struct m_tag *mtag; 143 struct tdb_ident *tdbi; 144 struct secpolicy *sp; 145 int s, error; 146 /* 147 * enforce IPsec policy checking if we are seeing last header. 148 * note that we do not visit this with protocols with pcb layer 149 * code - like udp/tcp/raw ip. 150 */ 151 if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) { 152 /* 153 * Check if the packet has already had IPsec processing 154 * done. If so, then just pass it along. This tag gets 155 * set during AH, ESP, etc. input handling, before the 156 * packet is returned to the ip input queue for delivery. 157 */ 158 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); 159 s = splnet(); 160 if (mtag != NULL) { 161 tdbi = (struct tdb_ident *)(mtag + 1); 162 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND); 163 } else { 164 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND, 165 IP_FORWARDING, &error); 166 } 167 if (sp != NULL) { 168 /* 169 * Check security policy against packet attributes. 170 */ 171 error = ipsec_in_reject(sp, m); 172 KEY_FREESP(&sp); 173 } else { 174 /* XXX error stat??? */ 175 error = EINVAL; 176 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/ 177 return 1; 178 } 179 splx(s); 180 if (error) 181 return 1; 182 } 183 #endif /* IPSEC */ 184 return 0; 185 } 186 187 /* 188 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated. 189 * Called from ip_forward(). 190 * Returns MTU suggestion for ICMP needfrag reply. 191 */ 192 int 193 ip_ipsec_mtu(struct mbuf *m) 194 { 195 int mtu = 0; 196 /* 197 * If the packet is routed over IPsec tunnel, tell the 198 * originator the tunnel MTU. 199 * tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz 200 * XXX quickhack!!! 201 */ 202 struct secpolicy *sp = NULL; 203 int ipsecerror; 204 int ipsechdr; 205 struct route *ro; 206 sp = ipsec_getpolicybyaddr(m, 207 IPSEC_DIR_OUTBOUND, 208 IP_FORWARDING, 209 &ipsecerror); 210 if (sp != NULL) { 211 /* count IPsec header size */ 212 ipsechdr = ipsec4_hdrsiz(m, 213 IPSEC_DIR_OUTBOUND, 214 NULL); 215 216 /* 217 * find the correct route for outer IPv4 218 * header, compute tunnel MTU. 219 */ 220 if (sp->req != NULL && 221 sp->req->sav != NULL && 222 sp->req->sav->sah != NULL) { 223 ro = &sp->req->sav->sah->sa_route; 224 if (ro->ro_rt && ro->ro_rt->rt_ifp) { 225 mtu = 226 ro->ro_rt->rt_rmx.rmx_mtu ? 227 ro->ro_rt->rt_rmx.rmx_mtu : 228 ro->ro_rt->rt_ifp->if_mtu; 229 mtu -= ipsechdr; 230 } 231 } 232 KEY_FREESP(&sp); 233 } 234 return mtu; 235 } 236 237 /* 238 * 239 * Called from ip_output(). 240 * 1 = drop packet, 0 = continue processing packet, 241 * -1 = packet was reinjected and stop processing packet 242 */ 243 int 244 ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error, 245 struct route **ro, struct route *iproute, struct sockaddr_in **dst, 246 struct in_ifaddr **ia, struct ifnet **ifp) 247 { 248 #ifdef IPSEC 249 struct secpolicy *sp = NULL; 250 struct ip *ip = mtod(*m, struct ip *); 251 struct tdb_ident *tdbi; 252 struct m_tag *mtag; 253 int s; 254 /* 255 * Check the security policy (SP) for the packet and, if 256 * required, do IPsec-related processing. There are two 257 * cases here; the first time a packet is sent through 258 * it will be untagged and handled by ipsec4_checkpolicy. 259 * If the packet is resubmitted to ip_output (e.g. after 260 * AH, ESP, etc. processing), there will be a tag to bypass 261 * the lookup and related policy checking. 262 */ 263 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL); 264 s = splnet(); 265 if (mtag != NULL) { 266 tdbi = (struct tdb_ident *)(mtag + 1); 267 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND); 268 if (sp == NULL) 269 *error = -EINVAL; /* force silent drop */ 270 m_tag_delete(*m, mtag); 271 } else { 272 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags, 273 error, inp); 274 } 275 /* 276 * There are four return cases: 277 * sp != NULL apply IPsec policy 278 * sp == NULL, error == 0 no IPsec handling needed 279 * sp == NULL, error == -EINVAL discard packet w/o error 280 * sp == NULL, error != 0 discard packet, report error 281 */ 282 if (sp != NULL) { 283 /* Loop detection, check if ipsec processing already done */ 284 KASSERT(sp->req != NULL, ("ip_output: no ipsec request")); 285 for (mtag = m_tag_first(*m); mtag != NULL; 286 mtag = m_tag_next(*m, mtag)) { 287 if (mtag->m_tag_cookie != MTAG_ABI_COMPAT) 288 continue; 289 if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE && 290 mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED) 291 continue; 292 /* 293 * Check if policy has an SA associated with it. 294 * This can happen when an SP has yet to acquire 295 * an SA; e.g. on first reference. If it occurs, 296 * then we let ipsec4_process_packet do its thing. 297 */ 298 if (sp->req->sav == NULL) 299 break; 300 tdbi = (struct tdb_ident *)(mtag + 1); 301 if (tdbi->spi == sp->req->sav->spi && 302 tdbi->proto == sp->req->sav->sah->saidx.proto && 303 bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst, 304 sizeof (union sockaddr_union)) == 0) { 305 /* 306 * No IPsec processing is needed, free 307 * reference to SP. 308 * 309 * NB: null pointer to avoid free at 310 * done: below. 311 */ 312 KEY_FREESP(&sp), sp = NULL; 313 splx(s); 314 goto done; 315 } 316 } 317 318 /* 319 * Do delayed checksums now because we send before 320 * this is done in the normal processing path. 321 */ 322 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) { 323 in_delayed_cksum(*m); 324 (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA; 325 } 326 327 ip->ip_len = htons(ip->ip_len); 328 ip->ip_off = htons(ip->ip_off); 329 330 /* NB: callee frees mbuf */ 331 *error = ipsec4_process_packet(*m, sp->req, *flags, 0); 332 /* 333 * Preserve KAME behaviour: ENOENT can be returned 334 * when an SA acquire is in progress. Don't propagate 335 * this to user-level; it confuses applications. 336 * 337 * XXX this will go away when the SADB is redone. 338 */ 339 if (*error == ENOENT) 340 *error = 0; 341 splx(s); 342 goto reinjected; 343 } else { /* sp == NULL */ 344 splx(s); 345 346 if (*error != 0) { 347 /* 348 * Hack: -EINVAL is used to signal that a packet 349 * should be silently discarded. This is typically 350 * because we asked key management for an SA and 351 * it was delayed (e.g. kicked up to IKE). 352 */ 353 if (*error == -EINVAL) 354 *error = 0; 355 goto bad; 356 } else { 357 /* No IPsec processing for this packet. */ 358 } 359 #ifdef notyet 360 /* 361 * If deferred crypto processing is needed, check that 362 * the interface supports it. 363 */ 364 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED, NULL); 365 if (mtag != NULL && ((*ifp)->if_capenable & IFCAP_IPSEC) == 0) { 366 /* notify IPsec to do its own crypto */ 367 ipsp_skipcrypto_unmark((struct tdb_ident *)(mtag + 1)); 368 *error = EHOSTUNREACH; 369 goto bad; 370 } 371 #endif 372 } 373 done: 374 if (sp != NULL) 375 KEY_FREESP(&sp); 376 return 0; 377 reinjected: 378 if (sp != NULL) 379 KEY_FREESP(&sp); 380 return -1; 381 bad: 382 if (sp != NULL) 383 KEY_FREESP(&sp); 384 return 1; 385 #endif /* IPSEC */ 386 return 0; 387 }
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