ip6_ipsec.c revision 174510
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: head/sys/netinet6/ip6_ipsec.c 174510 2007-12-10 16:03:40Z obrien $"); 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/mac.h> 39#include <sys/malloc.h> 40#include <sys/mbuf.h> 41#include <sys/protosw.h> 42#include <sys/socket.h> 43#include <sys/socketvar.h> 44#include <sys/sysctl.h> 45 46#include <net/if.h> 47#include <net/route.h> 48 49#include <netinet/in.h> 50#include <netinet/in_systm.h> 51#include <netinet/in_var.h> 52#include <netinet/ip.h> 53#include <netinet/in_pcb.h> 54#include <netinet/ip_var.h> 55#include <netinet/ip_options.h> 56 57#include <machine/in_cksum.h> 58 59#ifdef IPSEC 60#include <netipsec/ipsec.h> 61#include <netipsec/ipsec6.h> 62#include <netipsec/xform.h> 63#include <netipsec/key.h> 64#ifdef IPSEC_DEBUG 65#include <netipsec/key_debug.h> 66#else 67#define KEYDEBUG(lev,arg) 68#endif 69#endif /*IPSEC*/ 70 71#include <netinet6/ip6_ipsec.h> 72 73extern struct protosw inet6sw[]; 74 75/* 76 * Check if we have to jump over firewall processing for this packet. 77 * Called from ip_input(). 78 * 1 = jump over firewall, 0 = packet goes through firewall. 79 */ 80int 81ip6_ipsec_filtertunnel(struct mbuf *m) 82{ 83#if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL) 84 /* 85 * Bypass packet filtering for packets from a tunnel. 86 */ 87 if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL) 88 return 1; 89#endif 90 return 0; 91} 92 93/* 94 * Check if this packet has an active SA and needs to be dropped instead 95 * of forwarded. 96 * Called from ip_input(). 97 * 1 = drop packet, 0 = forward packet. 98 */ 99int 100ip6_ipsec_fwd(struct mbuf *m) 101{ 102#ifdef IPSEC 103 struct m_tag *mtag; 104 struct tdb_ident *tdbi; 105 struct secpolicy *sp; 106 int s, error; 107 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); 108 s = splnet(); 109 if (mtag != NULL) { 110 tdbi = (struct tdb_ident *)(mtag + 1); 111 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND); 112 } else { 113 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND, 114 IP_FORWARDING, &error); 115 } 116 if (sp == NULL) { /* NB: can happen if error */ 117 splx(s); 118 /*XXX error stat???*/ 119 DPRINTF(("ip_input: no SP for forwarding\n")); /*XXX*/ 120 return 1; 121 } 122 123 /* 124 * Check security policy against packet attributes. 125 */ 126 error = ipsec_in_reject(sp, m); 127 KEY_FREESP(&sp); 128 splx(s); 129 if (error) { 130 ipstat.ips_cantforward++; 131 return 1; 132 } 133#endif /* IPSEC */ 134 return 0; 135} 136 137/* 138 * Check if protocol type doesn't have a further header and do IPSEC 139 * decryption or reject right now. Protocols with further headers get 140 * their IPSEC treatment within the protocol specific processing. 141 * Called from ip_input(). 142 * 1 = drop packet, 0 = continue processing packet. 143 */ 144int 145ip6_ipsec_input(struct mbuf *m, int nxt) 146{ 147#ifdef IPSEC 148 struct m_tag *mtag; 149 struct tdb_ident *tdbi; 150 struct secpolicy *sp; 151 int s, error; 152 /* 153 * enforce IPsec policy checking if we are seeing last header. 154 * note that we do not visit this with protocols with pcb layer 155 * code - like udp/tcp/raw ip. 156 */ 157 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 && 158 ipsec6_in_reject(m, NULL)) { 159 160 /* 161 * Check if the packet has already had IPsec processing 162 * done. If so, then just pass it along. This tag gets 163 * set during AH, ESP, etc. input handling, before the 164 * packet is returned to the ip input queue for delivery. 165 */ 166 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); 167 s = splnet(); 168 if (mtag != NULL) { 169 tdbi = (struct tdb_ident *)(mtag + 1); 170 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND); 171 } else { 172 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND, 173 IP_FORWARDING, &error); 174 } 175 if (sp != NULL) { 176 /* 177 * Check security policy against packet attributes. 178 */ 179 error = ipsec_in_reject(sp, m); 180 KEY_FREESP(&sp); 181 } else { 182 /* XXX error stat??? */ 183 error = EINVAL; 184 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/ 185 return 1; 186 } 187 splx(s); 188 if (error) 189 return 1; 190 } 191#endif /* IPSEC */ 192 return 0; 193} 194 195/* 196 * Called from ip6_output(). 197 * 1 = drop packet, 0 = continue processing packet, 198 * -1 = packet was reinjected and stop processing packet 199 */ 200 201int 202ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error, 203 struct ifnet **ifp, struct secpolicy **sp) 204{ 205#ifdef IPSEC 206 struct tdb_ident *tdbi; 207 struct m_tag *mtag; 208 /* XXX int s; */ 209 if (sp == NULL) 210 return 1; 211 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL); 212 if (mtag != NULL) { 213 tdbi = (struct tdb_ident *)(mtag + 1); 214 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND); 215 if (*sp == NULL) 216 *error = -EINVAL; /* force silent drop */ 217 m_tag_delete(*m, mtag); 218 } else { 219 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags, 220 error, inp); 221 } 222 223 /* 224 * There are four return cases: 225 * sp != NULL apply IPsec policy 226 * sp == NULL, error == 0 no IPsec handling needed 227 * sp == NULL, error == -EINVAL discard packet w/o error 228 * sp == NULL, error != 0 discard packet, report error 229 */ 230 if (*sp != NULL) { 231 /* Loop detection, check if ipsec processing already done */ 232 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request")); 233 for (mtag = m_tag_first(*m); mtag != NULL; 234 mtag = m_tag_next(*m, mtag)) { 235 if (mtag->m_tag_cookie != MTAG_ABI_COMPAT) 236 continue; 237 if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE && 238 mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED) 239 continue; 240 /* 241 * Check if policy has an SA associated with it. 242 * This can happen when an SP has yet to acquire 243 * an SA; e.g. on first reference. If it occurs, 244 * then we let ipsec4_process_packet do its thing. 245 */ 246 if ((*sp)->req->sav == NULL) 247 break; 248 tdbi = (struct tdb_ident *)(mtag + 1); 249 if (tdbi->spi == (*sp)->req->sav->spi && 250 tdbi->proto == (*sp)->req->sav->sah->saidx.proto && 251 bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst, 252 sizeof (union sockaddr_union)) == 0) { 253 /* 254 * No IPsec processing is needed, free 255 * reference to SP. 256 * 257 * NB: null pointer to avoid free at 258 * done: below. 259 */ 260 KEY_FREESP(sp), sp = NULL; 261 /* XXX splx(s); */ 262 goto done; 263 } 264 } 265 266 /* 267 * Do delayed checksums now because we send before 268 * this is done in the normal processing path. 269 */ 270 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) { 271 in_delayed_cksum(*m); 272 (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA; 273 } 274 275 /* 276 * Preserve KAME behaviour: ENOENT can be returned 277 * when an SA acquire is in progress. Don't propagate 278 * this to user-level; it confuses applications. 279 * 280 * XXX this will go away when the SADB is redone. 281 */ 282 if (*error == ENOENT) 283 *error = 0; 284 goto do_ipsec; 285 } else { /* sp == NULL */ 286 if (*error != 0) { 287 /* 288 * Hack: -EINVAL is used to signal that a packet 289 * should be silently discarded. This is typically 290 * because we asked key management for an SA and 291 * it was delayed (e.g. kicked up to IKE). 292 */ 293 if (*error == -EINVAL) 294 *error = 0; 295 goto bad; 296 } else { 297 /* No IPsec processing for this packet. */ 298 } 299 } 300done: 301 if (sp != NULL) 302 if (*sp != NULL) 303 KEY_FREESP(sp); 304 return 0; 305do_ipsec: 306 return -1; 307bad: 308 if (sp != NULL) 309 if (*sp != NULL) 310 KEY_FREESP(sp); 311 return 1; 312#endif /* IPSEC */ 313 return 0; 314} 315 316/* 317 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated. 318 * Called from ip_forward(). 319 * Returns MTU suggestion for ICMP needfrag reply. 320 */ 321int 322ip6_ipsec_mtu(struct mbuf *m) 323{ 324 int mtu = 0; 325 /* 326 * If the packet is routed over IPsec tunnel, tell the 327 * originator the tunnel MTU. 328 * tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz 329 * XXX quickhack!!! 330 */ 331 struct secpolicy *sp = NULL; 332 int ipsecerror; 333 int ipsechdr; 334 struct route *ro; 335#ifdef IPSEC 336 sp = ipsec_getpolicybyaddr(m, 337 IPSEC_DIR_OUTBOUND, 338 IP_FORWARDING, 339 &ipsecerror); 340#endif /* IPSEC */ 341 if (sp != NULL) { 342 /* count IPsec header size */ 343 ipsechdr = ipsec4_hdrsiz(m, 344 IPSEC_DIR_OUTBOUND, 345 NULL); 346 347 /* 348 * find the correct route for outer IPv4 349 * header, compute tunnel MTU. 350 */ 351 if (sp->req != NULL && 352 sp->req->sav != NULL && 353 sp->req->sav->sah != NULL) { 354 ro = &sp->req->sav->sah->sa_route; 355 if (ro->ro_rt && ro->ro_rt->rt_ifp) { 356 mtu = 357 ro->ro_rt->rt_rmx.rmx_mtu ? 358 ro->ro_rt->rt_rmx.rmx_mtu : 359 ro->ro_rt->rt_ifp->if_mtu; 360 mtu -= ipsechdr; 361 } 362 } 363#ifdef IPSEC 364 KEY_FREESP(&sp); 365#endif /* IPSEC */ 366 } 367 return mtu; 368} 369 370