ip_ipsec.c revision 291355
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: stable/10/sys/netinet/ip_ipsec.c 291355 2015-11-26 02:24:45Z gnn $"); 32 33#include "opt_ipsec.h" 34#include "opt_sctp.h" 35 36#include <sys/param.h> 37#include <sys/systm.h> 38#include <sys/errno.h> 39#include <sys/kernel.h> 40#include <sys/malloc.h> 41#include <sys/mbuf.h> 42#include <sys/protosw.h> 43#include <sys/socket.h> 44#include <sys/socketvar.h> 45#include <sys/sysctl.h> 46 47#include <net/if.h> 48#include <net/vnet.h> 49 50#include <netinet/in.h> 51#include <netinet/in_systm.h> 52#include <netinet/in_var.h> 53#include <netinet/ip.h> 54#include <netinet/in_pcb.h> 55#include <netinet/ip_var.h> 56#include <netinet/ip_options.h> 57#include <netinet/ip_ipsec.h> 58#ifdef SCTP 59#include <netinet/sctp_crc32.h> 60#endif 61 62#include <machine/in_cksum.h> 63 64#ifdef IPSEC 65#include <netipsec/ipsec.h> 66#include <netipsec/xform.h> 67#include <netipsec/key.h> 68#endif /*IPSEC*/ 69 70extern struct protosw inetsw[]; 71 72#ifdef IPSEC 73#ifdef IPSEC_FILTERTUNNEL 74static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 1; 75#else 76static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 0; 77#endif 78#define V_ip4_ipsec_filtertunnel VNET(ip4_ipsec_filtertunnel) 79 80SYSCTL_DECL(_net_inet_ipsec); 81SYSCTL_VNET_INT(_net_inet_ipsec, OID_AUTO, filtertunnel, 82 CTLFLAG_RW, &VNET_NAME(ip4_ipsec_filtertunnel), 0, 83 "If set filter packets from an IPsec tunnel."); 84#endif /* IPSEC */ 85 86/* 87 * Check if we have to jump over firewall processing for this packet. 88 * Called from ip_input(). 89 * 1 = jump over firewall, 0 = packet goes through firewall. 90 */ 91int 92ip_ipsec_filtertunnel(struct mbuf *m) 93{ 94#ifdef IPSEC 95 96 /* 97 * Bypass packet filtering for packets previously handled by IPsec. 98 */ 99 if (!V_ip4_ipsec_filtertunnel && 100 m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL) 101 return 1; 102#endif 103 return 0; 104} 105 106/* 107 * Check if this packet has an active SA and needs to be dropped instead 108 * of forwarded. 109 * Called from ip_input(). 110 * 1 = drop packet, 0 = forward packet. 111 */ 112int 113ip_ipsec_fwd(struct mbuf *m) 114{ 115#ifdef IPSEC 116 struct m_tag *mtag; 117 struct tdb_ident *tdbi; 118 struct secpolicy *sp; 119 int error; 120 121 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); 122 if (mtag != NULL) { 123 tdbi = (struct tdb_ident *)(mtag + 1); 124 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND); 125 } else { 126 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND, 127 IP_FORWARDING, &error); 128 } 129 if (sp == NULL) { /* NB: can happen if error */ 130 /*XXX error stat???*/ 131 DPRINTF(("ip_input: no SP for forwarding\n")); /*XXX*/ 132 return 1; 133 } 134 135 /* 136 * Check security policy against packet attributes. 137 */ 138 error = ipsec_in_reject(sp, m); 139 KEY_FREESP(&sp); 140 if (error) { 141 IPSTAT_INC(ips_cantforward); 142 return 1; 143 } 144#endif /* IPSEC */ 145 return 0; 146} 147 148/* 149 * Check if protocol type doesn't have a further header and do IPSEC 150 * decryption or reject right now. Protocols with further headers get 151 * their IPSEC treatment within the protocol specific processing. 152 * Called from ip_input(). 153 * 1 = drop packet, 0 = continue processing packet. 154 */ 155int 156ip_ipsec_input(struct mbuf *m) 157{ 158#ifdef IPSEC 159 struct ip *ip = mtod(m, struct ip *); 160 struct m_tag *mtag; 161 struct tdb_ident *tdbi; 162 struct secpolicy *sp; 163 int error; 164 /* 165 * enforce IPsec policy checking if we are seeing last header. 166 * note that we do not visit this with protocols with pcb layer 167 * code - like udp/tcp/raw ip. 168 */ 169 if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) { 170 /* 171 * Check if the packet has already had IPsec processing 172 * done. If so, then just pass it along. This tag gets 173 * set during AH, ESP, etc. input handling, before the 174 * packet is returned to the ip input queue for delivery. 175 */ 176 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); 177 if (mtag != NULL) { 178 tdbi = (struct tdb_ident *)(mtag + 1); 179 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND); 180 } else { 181 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND, 182 IP_FORWARDING, &error); 183 } 184 if (sp != NULL) { 185 /* 186 * Check security policy against packet attributes. 187 */ 188 error = ipsec_in_reject(sp, m); 189 KEY_FREESP(&sp); 190 } else { 191 /* XXX error stat??? */ 192 error = EINVAL; 193 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/ 194 return 1; 195 } 196 if (error) 197 return 1; 198 } 199#endif /* IPSEC */ 200 return 0; 201} 202 203/* 204 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated. 205 * Called from ip_forward(). 206 * Returns MTU suggestion for ICMP needfrag reply. 207 */ 208int 209ip_ipsec_mtu(struct mbuf *m, int mtu) 210{ 211 /* 212 * If the packet is routed over IPsec tunnel, tell the 213 * originator the tunnel MTU. 214 * tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz 215 * XXX quickhack!!! 216 */ 217 return (mtu - ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL)); 218} 219 220/* 221 * 222 * Called from ip_output(). 223 * 1 = drop packet, 0 = continue processing packet, 224 * -1 = packet was reinjected and stop processing packet 225 */ 226int 227ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error) 228{ 229#ifdef IPSEC 230 struct secpolicy *sp = NULL; 231 struct tdb_ident *tdbi; 232 struct m_tag *mtag; 233 234 if (!key_havesp(IPSEC_DIR_OUTBOUND)) 235 return 0; 236 237 /* 238 * Check the security policy (SP) for the packet and, if 239 * required, do IPsec-related processing. There are two 240 * cases here; the first time a packet is sent through 241 * it will be untagged and handled by ipsec4_checkpolicy. 242 * If the packet is resubmitted to ip_output (e.g. after 243 * AH, ESP, etc. processing), there will be a tag to bypass 244 * the lookup and related policy checking. 245 */ 246 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL); 247 if (mtag != NULL) { 248 tdbi = (struct tdb_ident *)(mtag + 1); 249 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND); 250 if (sp == NULL) 251 *error = -EINVAL; /* force silent drop */ 252 m_tag_delete(*m, mtag); 253 } else { 254 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags, 255 error, inp); 256 } 257 /* 258 * There are four return cases: 259 * sp != NULL apply IPsec policy 260 * sp == NULL, error == 0 no IPsec handling needed 261 * sp == NULL, error == -EINVAL discard packet w/o error 262 * sp == NULL, error != 0 discard packet, report error 263 */ 264 if (sp != NULL) { 265 /* Loop detection, check if ipsec processing already done */ 266 KASSERT(sp->req != NULL, ("ip_output: no ipsec request")); 267 for (mtag = m_tag_first(*m); mtag != NULL; 268 mtag = m_tag_next(*m, mtag)) { 269 if (mtag->m_tag_cookie != MTAG_ABI_COMPAT) 270 continue; 271 if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE && 272 mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED) 273 continue; 274 /* 275 * Check if policy has an SA associated with it. 276 * This can happen when an SP has yet to acquire 277 * an SA; e.g. on first reference. If it occurs, 278 * then we let ipsec4_process_packet do its thing. 279 */ 280 if (sp->req->sav == NULL) 281 break; 282 tdbi = (struct tdb_ident *)(mtag + 1); 283 if (tdbi->spi == sp->req->sav->spi && 284 tdbi->proto == sp->req->sav->sah->saidx.proto && 285 bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst, 286 sizeof (union sockaddr_union)) == 0) { 287 /* 288 * No IPsec processing is needed, free 289 * reference to SP. 290 * 291 * NB: null pointer to avoid free at 292 * done: below. 293 */ 294 KEY_FREESP(&sp), sp = NULL; 295 goto done; 296 } 297 } 298 299 /* 300 * Do delayed checksums now because we send before 301 * this is done in the normal processing path. 302 */ 303 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) { 304 in_delayed_cksum(*m); 305 (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA; 306 } 307#ifdef SCTP 308 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP) { 309 struct ip *ip = mtod(*m, struct ip *); 310 311 sctp_delayed_cksum(*m, (uint32_t)(ip->ip_hl << 2)); 312 (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP; 313 } 314#endif 315 316 /* NB: callee frees mbuf */ 317 *error = ipsec4_process_packet(*m, sp->req, *flags, 0); 318 if (*error == EJUSTRETURN) { 319 /* 320 * We had a SP with a level of 'use' and no SA. We 321 * will just continue to process the packet without 322 * IPsec processing and return without error. 323 */ 324 *error = 0; 325 goto done; 326 } 327 /* 328 * Preserve KAME behaviour: ENOENT can be returned 329 * when an SA acquire is in progress. Don't propagate 330 * this to user-level; it confuses applications. 331 * 332 * XXX this will go away when the SADB is redone. 333 */ 334 if (*error == ENOENT) 335 *error = 0; 336 goto reinjected; 337 } else { /* sp == NULL */ 338 339 if (*error != 0) { 340 /* 341 * Hack: -EINVAL is used to signal that a packet 342 * should be silently discarded. This is typically 343 * because we asked key management for an SA and 344 * it was delayed (e.g. kicked up to IKE). 345 */ 346 if (*error == -EINVAL) 347 *error = 0; 348 goto bad; 349 } else { 350 /* No IPsec processing for this packet. */ 351 } 352 } 353done: 354 if (sp != NULL) 355 KEY_FREESP(&sp); 356 return 0; 357reinjected: 358 if (sp != NULL) 359 KEY_FREESP(&sp); 360 return -1; 361bad: 362 if (sp != NULL) 363 KEY_FREESP(&sp); 364 return 1; 365#endif /* IPSEC */ 366 return 0; 367} 368