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/errno.h>
38 #include <sys/kernel.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 #include <netinet/ip_ipsec.h>
57
58 #include <machine/in_cksum.h>
59
60 #ifdef IPSEC
61 #include <netipsec/ipsec.h>
62 #include <netipsec/xform.h>
63 #include <netipsec/key.h>
64 #endif /*IPSEC*/
65
66 extern struct protosw inetsw[];
67
68 /*
69 * Check if we have to jump over firewall processing for this packet.
70 * Called from ip_input().
71 * 1 = jump over firewall, 0 = packet goes through firewall.
72 */
73 int
74 ip_ipsec_filtertunnel(struct mbuf *m)
75 {
76 #if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL)
77 /*
78 * Bypass packet filtering for packets from a tunnel.
79 */
80 if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
81 return 1;
82 #endif
83 return 0;
84 }
85
86 /*
87 * Check if this packet has an active SA and needs to be dropped instead
88 * of forwarded.
89 * Called from ip_input().
90 * 1 = drop packet, 0 = forward packet.
91 */
92 int
93 ip_ipsec_fwd(struct mbuf *m)
94 {
95 #ifdef IPSEC
96 struct m_tag *mtag;
97 struct tdb_ident *tdbi;
98 struct secpolicy *sp;
99 int s, error;
100
101 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
102 s = splnet();
103 if (mtag != NULL) {
104 tdbi = (struct tdb_ident *)(mtag + 1);
105 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
106 } else {
107 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
108 IP_FORWARDING, &error);
109 }
110 if (sp == NULL) { /* NB: can happen if error */
111 splx(s);
112 /*XXX error stat???*/
113 DPRINTF(("ip_input: no SP for forwarding\n")); /*XXX*/
114 return 1;
115 }
116
117 /*
118 * Check security policy against packet attributes.
119 */
120 error = ipsec_in_reject(sp, m);
121 KEY_FREESP(&sp);
122 splx(s);
123 if (error) {
124 ipstat.ips_cantforward++;
125 return 1;
126 }
127 #endif /* IPSEC */
128 return 0;
129 }
130
131 /*
132 * Check if protocol type doesn't have a further header and do IPSEC
133 * decryption or reject right now. Protocols with further headers get
134 * their IPSEC treatment within the protocol specific processing.
135 * Called from ip_input().
136 * 1 = drop packet, 0 = continue processing packet.
137 */
138 int
139 ip_ipsec_input(struct mbuf *m)
140 {
141 struct ip *ip = mtod(m, struct ip *);
142 #ifdef IPSEC
143 struct m_tag *mtag;
144 struct tdb_ident *tdbi;
145 struct secpolicy *sp;
146 int s, error;
147 /*
148 * enforce IPsec policy checking if we are seeing last header.
149 * note that we do not visit this with protocols with pcb layer
150 * code - like udp/tcp/raw ip.
151 */
152 if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
153 /*
154 * Check if the packet has already had IPsec processing
155 * done. If so, then just pass it along. This tag gets
156 * set during AH, ESP, etc. input handling, before the
157 * packet is returned to the ip input queue for delivery.
158 */
159 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
160 s = splnet();
161 if (mtag != NULL) {
162 tdbi = (struct tdb_ident *)(mtag + 1);
163 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
164 } else {
165 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
166 IP_FORWARDING, &error);
167 }
168 if (sp != NULL) {
169 /*
170 * Check security policy against packet attributes.
171 */
172 error = ipsec_in_reject(sp, m);
173 KEY_FREESP(&sp);
174 } else {
175 /* XXX error stat??? */
176 error = EINVAL;
177 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
178 return 1;
179 }
180 splx(s);
181 if (error)
182 return 1;
183 }
184 #endif /* IPSEC */
185 return 0;
186 }
187
188 /*
189 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
190 * Called from ip_forward().
191 * Returns MTU suggestion for ICMP needfrag reply.
192 */
193 int
194 ip_ipsec_mtu(struct mbuf *m, int mtu)
195 {
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 if (*error == EJUSTRETURN) {
333 /*
334 * We had a SP with a level of 'use' and no SA. We
335 * will just continue to process the packet without
336 * IPsec processing and return without error.
337 */
338 *error = 0;
339 ip->ip_len = ntohs(ip->ip_len);
340 ip->ip_off = ntohs(ip->ip_off);
341 goto done;
342 }
343 /*
344 * Preserve KAME behaviour: ENOENT can be returned
345 * when an SA acquire is in progress. Don't propagate
346 * this to user-level; it confuses applications.
347 *
348 * XXX this will go away when the SADB is redone.
349 */
350 if (*error == ENOENT)
351 *error = 0;
352 splx(s);
353 goto reinjected;
354 } else { /* sp == NULL */
355 splx(s);
356
357 if (*error != 0) {
358 /*
359 * Hack: -EINVAL is used to signal that a packet
360 * should be silently discarded. This is typically
361 * because we asked key management for an SA and
362 * it was delayed (e.g. kicked up to IKE).
363 */
364 if (*error == -EINVAL)
365 *error = 0;
366 goto bad;
367 } else {
368 /* No IPsec processing for this packet. */
369 }
370 #ifdef notyet
371 /*
372 * If deferred crypto processing is needed, check that
373 * the interface supports it.
374 */
375 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED, NULL);
376 if (mtag != NULL && ((*ifp)->if_capenable & IFCAP_IPSEC) == 0) {
377 /* notify IPsec to do its own crypto */
378 ipsp_skipcrypto_unmark((struct tdb_ident *)(mtag + 1));
379 *error = EHOSTUNREACH;
380 goto bad;
381 }
382 #endif
383 }
384 done:
385 if (sp != NULL)
386 KEY_FREESP(&sp);
387 return 0;
388 reinjected:
389 if (sp != NULL)
390 KEY_FREESP(&sp);
391 return -1;
392 bad:
393 if (sp != NULL)
394 KEY_FREESP(&sp);
395 return 1;
396 #endif /* IPSEC */
397 return 0;
398 }
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