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/netinet/ip_ipsec.c 183550 2008-10-02 15:37:58Z zec $");
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#include <sys/vimage.h>
46
47#include <net/if.h>
48#include <net/route.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
59#include <machine/in_cksum.h>
60
61#ifdef IPSEC
62#include <netipsec/ipsec.h>
63#include <netipsec/xform.h>
64#include <netipsec/key.h>
65#endif /*IPSEC*/
66
67extern struct protosw inetsw[];
68
69/*
70 * Check if we have to jump over firewall processing for this packet.
71 * Called from ip_input().
72 * 1 = jump over firewall, 0 = packet goes through firewall.
73 */
74int
75ip_ipsec_filtertunnel(struct mbuf *m)
76{
77#if defined(IPSEC) && !defined(IPSEC_FILTERTUNNEL)
78 /*
79 * Bypass packet filtering for packets from a tunnel.
80 */
81 if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
82 return 1;
83#endif
84 return 0;
85}
86
87/*
88 * Check if this packet has an active SA and needs to be dropped instead
89 * of forwarded.
90 * Called from ip_input().
91 * 1 = drop packet, 0 = forward packet.
92 */
93int
94ip_ipsec_fwd(struct mbuf *m)
95{
96#ifdef IPSEC
97 INIT_VNET_INET(curvnet);
98 INIT_VNET_IPSEC(curvnet);
99 struct m_tag *mtag;
100 struct tdb_ident *tdbi;
101 struct secpolicy *sp;
102 int s, error;
103
104 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
105 s = splnet();
106 if (mtag != NULL) {
107 tdbi = (struct tdb_ident *)(mtag + 1);
108 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
109 } else {
110 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
111 IP_FORWARDING, &error);
112 }
113 if (sp == NULL) { /* NB: can happen if error */
114 splx(s);
115 /*XXX error stat???*/
116 DPRINTF(("ip_input: no SP for forwarding\n")); /*XXX*/
117 return 1;
118 }
119
120 /*
121 * Check security policy against packet attributes.
122 */
123 error = ipsec_in_reject(sp, m);
124 KEY_FREESP(&sp);
125 splx(s);
126 if (error) {
127 V_ipstat.ips_cantforward++;
128 return 1;
129 }
130#endif /* IPSEC */
131 return 0;
132}
133
134/*
135 * Check if protocol type doesn't have a further header and do IPSEC
136 * decryption or reject right now. Protocols with further headers get
137 * their IPSEC treatment within the protocol specific processing.
138 * Called from ip_input().
139 * 1 = drop packet, 0 = continue processing packet.
140 */
141int
142ip_ipsec_input(struct mbuf *m)
143{
144 struct ip *ip = mtod(m, struct ip *);
145#ifdef IPSEC
146 INIT_VNET_IPSEC(curvnet);
147 struct m_tag *mtag;
148 struct tdb_ident *tdbi;
149 struct secpolicy *sp;
150 int s, error;
151 /*
152 * enforce IPsec policy checking if we are seeing last header.
153 * note that we do not visit this with protocols with pcb layer
154 * code - like udp/tcp/raw ip.
155 */
156 if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
157 /*
158 * Check if the packet has already had IPsec processing
159 * done. If so, then just pass it along. This tag gets
160 * set during AH, ESP, etc. input handling, before the
161 * packet is returned to the ip input queue for delivery.
162 */
163 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
164 s = splnet();
165 if (mtag != NULL) {
166 tdbi = (struct tdb_ident *)(mtag + 1);
167 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
168 } else {
169 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
170 IP_FORWARDING, &error);
171 }
172 if (sp != NULL) {
173 /*
174 * Check security policy against packet attributes.
175 */
176 error = ipsec_in_reject(sp, m);
177 KEY_FREESP(&sp);
178 } else {
179 /* XXX error stat??? */
180 error = EINVAL;
181 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
182 return 1;
183 }
184 splx(s);
185 if (error)
186 return 1;
187 }
188#endif /* IPSEC */
189 return 0;
190}
191
192/*
193 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
194 * Called from ip_forward().
195 * Returns MTU suggestion for ICMP needfrag reply.
196 */
197int
198ip_ipsec_mtu(struct mbuf *m, int mtu)
199{
200 /*
201 * If the packet is routed over IPsec tunnel, tell the
202 * originator the tunnel MTU.
203 * tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
204 * XXX quickhack!!!
205 */
206 struct secpolicy *sp = NULL;
207 int ipsecerror;
208 int ipsechdr;
209 struct route *ro;
210 sp = ipsec_getpolicybyaddr(m,
211 IPSEC_DIR_OUTBOUND,
212 IP_FORWARDING,
213 &ipsecerror);
214 if (sp != NULL) {
215 /* count IPsec header size */
216 ipsechdr = ipsec4_hdrsiz(m,
217 IPSEC_DIR_OUTBOUND,
218 NULL);
219
220 /*
221 * find the correct route for outer IPv4
222 * header, compute tunnel MTU.
223 */
224 if (sp->req != NULL &&
225 sp->req->sav != NULL &&
226 sp->req->sav->sah != NULL) {
227 ro = &sp->req->sav->sah->sa_route;
228 if (ro->ro_rt && ro->ro_rt->rt_ifp) {
229 mtu =
230 ro->ro_rt->rt_rmx.rmx_mtu ?
231 ro->ro_rt->rt_rmx.rmx_mtu :
232 ro->ro_rt->rt_ifp->if_mtu;
233 mtu -= ipsechdr;
234 }
235 }
236 KEY_FREESP(&sp);
237 }
238 return mtu;
239}
240
241/*
242 *
243 * Called from ip_output().
244 * 1 = drop packet, 0 = continue processing packet,
245 * -1 = packet was reinjected and stop processing packet
246 */
247int
248ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
249 struct route **ro, struct route *iproute, struct sockaddr_in **dst,
250 struct in_ifaddr **ia, struct ifnet **ifp)
251{
252#ifdef IPSEC
253 struct secpolicy *sp = NULL;
254 struct ip *ip = mtod(*m, struct ip *);
255 struct tdb_ident *tdbi;
256 struct m_tag *mtag;
257 int s;
258 /*
259 * Check the security policy (SP) for the packet and, if
260 * required, do IPsec-related processing. There are two
261 * cases here; the first time a packet is sent through
262 * it will be untagged and handled by ipsec4_checkpolicy.
263 * If the packet is resubmitted to ip_output (e.g. after
264 * AH, ESP, etc. processing), there will be a tag to bypass
265 * the lookup and related policy checking.
266 */
267 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
268 s = splnet();
269 if (mtag != NULL) {
270 tdbi = (struct tdb_ident *)(mtag + 1);
271 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
272 if (sp == NULL)
273 *error = -EINVAL; /* force silent drop */
274 m_tag_delete(*m, mtag);
275 } else {
276 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
277 error, inp);
278 }
279 /*
280 * There are four return cases:
281 * sp != NULL apply IPsec policy
282 * sp == NULL, error == 0 no IPsec handling needed
283 * sp == NULL, error == -EINVAL discard packet w/o error
284 * sp == NULL, error != 0 discard packet, report error
285 */
286 if (sp != NULL) {
287 /* Loop detection, check if ipsec processing already done */
288 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
289 for (mtag = m_tag_first(*m); mtag != NULL;
290 mtag = m_tag_next(*m, mtag)) {
291 if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
292 continue;
293 if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
294 mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
295 continue;
296 /*
297 * Check if policy has an SA associated with it.
298 * This can happen when an SP has yet to acquire
299 * an SA; e.g. on first reference. If it occurs,
300 * then we let ipsec4_process_packet do its thing.
301 */
302 if (sp->req->sav == NULL)
303 break;
304 tdbi = (struct tdb_ident *)(mtag + 1);
305 if (tdbi->spi == sp->req->sav->spi &&
306 tdbi->proto == sp->req->sav->sah->saidx.proto &&
307 bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
308 sizeof (union sockaddr_union)) == 0) {
309 /*
310 * No IPsec processing is needed, free
311 * reference to SP.
312 *
313 * NB: null pointer to avoid free at
314 * done: below.
315 */
316 KEY_FREESP(&sp), sp = NULL;
317 splx(s);
318 goto done;
319 }
320 }
321
322 /*
323 * Do delayed checksums now because we send before
324 * this is done in the normal processing path.
325 */
326 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
327 in_delayed_cksum(*m);
328 (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
329 }
330
331 ip->ip_len = htons(ip->ip_len);
332 ip->ip_off = htons(ip->ip_off);
333
334 /* NB: callee frees mbuf */
335 *error = ipsec4_process_packet(*m, sp->req, *flags, 0);
336 if (*error == EJUSTRETURN) {
337 /*
338 * We had a SP with a level of 'use' and no SA. We
339 * will just continue to process the packet without
340 * IPsec processing and return without error.
341 */
342 *error = 0;
343 ip->ip_len = ntohs(ip->ip_len);
344 ip->ip_off = ntohs(ip->ip_off);
345 goto done;
346 }
347 /*
348 * Preserve KAME behaviour: ENOENT can be returned
349 * when an SA acquire is in progress. Don't propagate
350 * this to user-level; it confuses applications.
351 *
352 * XXX this will go away when the SADB is redone.
353 */
354 if (*error == ENOENT)
355 *error = 0;
356 splx(s);
357 goto reinjected;
358 } else { /* sp == NULL */
359 splx(s);
360
361 if (*error != 0) {
362 /*
363 * Hack: -EINVAL is used to signal that a packet
364 * should be silently discarded. This is typically
365 * because we asked key management for an SA and
366 * it was delayed (e.g. kicked up to IKE).
367 */
368 if (*error == -EINVAL)
369 *error = 0;
370 goto bad;
371 } else {
372 /* No IPsec processing for this packet. */
373 }
374#ifdef notyet
375 /*
376 * If deferred crypto processing is needed, check that
377 * the interface supports it.
378 */
379 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED, NULL);
380 if (mtag != NULL && ((*ifp)->if_capenable & IFCAP_IPSEC) == 0) {
381 /* notify IPsec to do its own crypto */
382 ipsp_skipcrypto_unmark((struct tdb_ident *)(mtag + 1));
383 *error = EHOSTUNREACH;
384 goto bad;
385 }
386#endif
387 }
388done:
389 if (sp != NULL)
390 KEY_FREESP(&sp);
391 return 0;
392reinjected:
393 if (sp != NULL)
394 KEY_FREESP(&sp);
395 return -1;
396bad:
397 if (sp != NULL)
398 KEY_FREESP(&sp);
399 return 1;
400#endif /* IPSEC */
401 return 0;
402}