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/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 #include <netinet6/ip6_var.h>
73
74 extern struct protosw inet6sw[];
75
76 /*
77 * Check if we have to jump over firewall processing for this packet.
78 * Called from ip6_input().
79 * 1 = jump over firewall, 0 = packet goes through firewall.
80 */
81 int
82 ip6_ipsec_filtertunnel(struct mbuf *m)
83 {
84 #if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL)
85 /*
86 * Bypass packet filtering for packets previously handled by IPsec.
87 */
88 if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
89 return 1;
90 #endif
91 return 0;
92 }
93
94 /*
95 * Check if this packet has an active SA and needs to be dropped instead
96 * of forwarded.
97 * Called from ip6_input().
98 * 1 = drop packet, 0 = forward packet.
99 */
100 int
101 ip6_ipsec_fwd(struct mbuf *m)
102 {
103 #ifdef IPSEC
104 struct m_tag *mtag;
105 struct tdb_ident *tdbi;
106 struct secpolicy *sp;
107 int s, error;
108 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
109 s = splnet();
110 if (mtag != NULL) {
111 tdbi = (struct tdb_ident *)(mtag + 1);
112 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
113 } else {
114 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
115 IP_FORWARDING, &error);
116 }
117 if (sp == NULL) { /* NB: can happen if error */
118 splx(s);
119 /*XXX error stat???*/
120 DPRINTF(("%s: no SP for forwarding\n", __func__)); /*XXX*/
121 return 1;
122 }
123
124 /*
125 * Check security policy against packet attributes.
126 */
127 error = ipsec_in_reject(sp, m);
128 KEY_FREESP(&sp);
129 splx(s);
130 if (error) {
131 ip6stat.ip6s_cantforward++;
132 return 1;
133 }
134 #endif /* IPSEC */
135 return 0;
136 }
137
138 /*
139 * Check if protocol type doesn't have a further header and do IPSEC
140 * decryption or reject right now. Protocols with further headers get
141 * their IPSEC treatment within the protocol specific processing.
142 * Called from ip6_input().
143 * 1 = drop packet, 0 = continue processing packet.
144 */
145 int
146 ip6_ipsec_input(struct mbuf *m, int nxt)
147 {
148 #ifdef IPSEC
149 struct m_tag *mtag;
150 struct tdb_ident *tdbi;
151 struct secpolicy *sp;
152 int s, error;
153 /*
154 * enforce IPsec policy checking if we are seeing last header.
155 * note that we do not visit this with protocols with pcb layer
156 * code - like udp/tcp/raw ip.
157 */
158 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
159 ipsec6_in_reject(m, NULL)) {
160
161 /*
162 * Check if the packet has already had IPsec processing
163 * done. If so, then just pass it along. This tag gets
164 * set during AH, ESP, etc. input handling, before the
165 * packet is returned to the ip input queue for delivery.
166 */
167 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
168 s = splnet();
169 if (mtag != NULL) {
170 tdbi = (struct tdb_ident *)(mtag + 1);
171 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
172 } else {
173 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
174 IP_FORWARDING, &error);
175 }
176 if (sp != NULL) {
177 /*
178 * Check security policy against packet attributes.
179 */
180 error = ipsec_in_reject(sp, m);
181 KEY_FREESP(&sp);
182 } else {
183 /* XXX error stat??? */
184 error = EINVAL;
185 DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
186 return 1;
187 }
188 splx(s);
189 if (error)
190 return 1;
191 }
192 #endif /* IPSEC */
193 return 0;
194 }
195
196 /*
197 * Called from ip6_output().
198 * 1 = drop packet, 0 = continue processing packet,
199 * -1 = packet was reinjected and stop processing packet
200 */
201
202 int
203 ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
204 struct ifnet **ifp, struct secpolicy **sp)
205 {
206 #ifdef IPSEC
207 struct tdb_ident *tdbi;
208 struct m_tag *mtag;
209 /* XXX int s; */
210 if (sp == NULL)
211 return 1;
212 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
213 if (mtag != NULL) {
214 tdbi = (struct tdb_ident *)(mtag + 1);
215 *sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
216 if (*sp == NULL)
217 *error = -EINVAL; /* force silent drop */
218 m_tag_delete(*m, mtag);
219 } else {
220 *sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
221 error, inp);
222 }
223
224 /*
225 * There are four return cases:
226 * sp != NULL apply IPsec policy
227 * sp == NULL, error == 0 no IPsec handling needed
228 * sp == NULL, error == -EINVAL discard packet w/o error
229 * sp == NULL, error != 0 discard packet, report error
230 */
231 if (*sp != NULL) {
232 /* Loop detection, check if ipsec processing already done */
233 KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
234 for (mtag = m_tag_first(*m); mtag != NULL;
235 mtag = m_tag_next(*m, mtag)) {
236 if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
237 continue;
238 if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
239 mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
240 continue;
241 /*
242 * Check if policy has no SA associated with it.
243 * This can happen when an SP has yet to acquire
244 * an SA; e.g. on first reference. If it occurs,
245 * then we let ipsec4_process_packet do its thing.
246 */
247 if ((*sp)->req->sav == NULL)
248 break;
249 tdbi = (struct tdb_ident *)(mtag + 1);
250 if (tdbi->spi == (*sp)->req->sav->spi &&
251 tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
252 bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
253 sizeof (union sockaddr_union)) == 0) {
254 /*
255 * No IPsec processing is needed, free
256 * reference to SP.
257 *
258 * NB: null pointer to avoid free at
259 * done: below.
260 */
261 KEY_FREESP(sp), *sp = NULL;
262 /* XXX splx(s); */
263 goto done;
264 }
265 }
266
267 /*
268 * Do delayed checksums now because we send before
269 * this is done in the normal processing path.
270 */
271 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
272 in_delayed_cksum(*m);
273 (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
274 }
275
276 /*
277 * Preserve KAME behaviour: ENOENT can be returned
278 * when an SA acquire is in progress. Don't propagate
279 * this to user-level; it confuses applications.
280 *
281 * XXX this will go away when the SADB is redone.
282 */
283 if (*error == ENOENT)
284 *error = 0;
285 goto do_ipsec;
286 } else { /* sp == NULL */
287 if (*error != 0) {
288 /*
289 * Hack: -EINVAL is used to signal that a packet
290 * should be silently discarded. This is typically
291 * because we asked key management for an SA and
292 * it was delayed (e.g. kicked up to IKE).
293 */
294 if (*error == -EINVAL)
295 *error = 0;
296 goto bad;
297 } else {
298 /* No IPsec processing for this packet. */
299 }
300 }
301 done:
302 return 0;
303 do_ipsec:
304 return -1;
305 bad:
306 return 1;
307 #endif /* IPSEC */
308 return 0;
309 }
310
311 #if 0
312 /*
313 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
314 * Called from ip_forward().
315 * Returns MTU suggestion for ICMP needfrag reply.
316 */
317 int
318 ip6_ipsec_mtu(struct mbuf *m)
319 {
320 int mtu = 0;
321 /*
322 * If the packet is routed over IPsec tunnel, tell the
323 * originator the tunnel MTU.
324 * tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
325 * XXX quickhack!!!
326 */
327 #ifdef IPSEC
328 struct secpolicy *sp = NULL;
329 int ipsecerror;
330 int ipsechdr;
331 struct route *ro;
332 sp = ipsec_getpolicybyaddr(m,
333 IPSEC_DIR_OUTBOUND,
334 IP_FORWARDING,
335 &ipsecerror);
336 if (sp != NULL) {
337 /* count IPsec header size */
338 ipsechdr = ipsec4_hdrsiz(m,
339 IPSEC_DIR_OUTBOUND,
340 NULL);
341
342 /*
343 * find the correct route for outer IPv4
344 * header, compute tunnel MTU.
345 */
346 if (sp->req != NULL &&
347 sp->req->sav != NULL &&
348 sp->req->sav->sah != NULL) {
349 ro = &sp->req->sav->sah->route_cache.sa_route;
350 if (ro->ro_rt && ro->ro_rt->rt_ifp) {
351 mtu =
352 ro->ro_rt->rt_rmx.rmx_mtu ?
353 ro->ro_rt->rt_rmx.rmx_mtu :
354 ro->ro_rt->rt_ifp->if_mtu;
355 mtu -= ipsechdr;
356 }
357 }
358 KEY_FREESP(&sp);
359 }
360 #endif /* IPSEC */
361 /* XXX else case missing. */
362 return mtu;
363 }
364 #endif
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