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/9/sys/netinet/ip_ipsec.c 222845 2011-06-08 03:02:11Z bz $");
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/route.h>
49 #include <net/vnet.h>
50
51 #include <netinet/in.h>
52 #include <netinet/in_systm.h>
53 #include <netinet/in_var.h>
54 #include <netinet/ip.h>
55 #include <netinet/in_pcb.h>
56 #include <netinet/ip_var.h>
57 #include <netinet/ip_options.h>
58 #include <netinet/ip_ipsec.h>
59 #ifdef SCTP
60 #include <netinet/sctp_crc32.h>
61 #endif
62
63 #include <machine/in_cksum.h>
64
65 #ifdef IPSEC
66 #include <netipsec/ipsec.h>
67 #include <netipsec/xform.h>
68 #include <netipsec/key.h>
69 #endif /*IPSEC*/
70
71 extern struct protosw inetsw[];
72
73 #ifdef IPSEC
74 #ifdef IPSEC_FILTERTUNNEL
75 static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 1;
76 #else
77 static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 0;
78 #endif
79 #define V_ip4_ipsec_filtertunnel VNET(ip4_ipsec_filtertunnel)
80
81 SYSCTL_DECL(_net_inet_ipsec);
82 SYSCTL_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 */
92 int
ip_ipsec_filtertunnel(struct mbuf * m)93 ip_ipsec_filtertunnel(struct mbuf *m)
94 {
95 #if defined(IPSEC)
96
97 /*
98 * Bypass packet filtering for packets previously handled by IPsec.
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 */
113 int
ip_ipsec_fwd(struct mbuf * m)114 ip_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 */
159 int
ip_ipsec_input(struct mbuf * m)160 ip_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 */
214 int
ip_ipsec_mtu(struct mbuf * m,int mtu)215 ip_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 */
262 int
ip_ipsec_output(struct mbuf ** m,struct inpcb * inp,int * flags,int * error)263 ip_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 }
393 done:
394 if (sp != NULL)
395 KEY_FREESP(&sp);
396 return 0;
397 reinjected:
398 if (sp != NULL)
399 KEY_FREESP(&sp);
400 return -1;
401 bad:
402 if (sp != NULL)
403 KEY_FREESP(&sp);
404 return 1;
405 #endif /* IPSEC */
406 return 0;
407 }
408