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 #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
70 extern struct protosw inetsw[];
71
72 #ifdef IPSEC
73 #ifdef IPSEC_FILTERTUNNEL
74 static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 1;
75 #else
76 static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 0;
77 #endif
78 #define V_ip4_ipsec_filtertunnel VNET(ip4_ipsec_filtertunnel)
79
80 SYSCTL_DECL(_net_inet_ipsec);
81 SYSCTL_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 */
91 int
ip_ipsec_filtertunnel(struct mbuf * m)92 ip_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 */
112 int
ip_ipsec_fwd(struct mbuf * m)113 ip_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 */
155 int
ip_ipsec_input(struct mbuf * m)156 ip_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 */
208 int
ip_ipsec_mtu(struct mbuf * m,int mtu)209 ip_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 */
226 int
ip_ipsec_output(struct mbuf ** m,struct inpcb * inp,int * flags,int * error)227 ip_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 * Check the security policy (SP) for the packet and, if
235 * required, do IPsec-related processing. There are two
236 * cases here; the first time a packet is sent through
237 * it will be untagged and handled by ipsec4_checkpolicy.
238 * If the packet is resubmitted to ip_output (e.g. after
239 * AH, ESP, etc. processing), there will be a tag to bypass
240 * the lookup and related policy checking.
241 */
242 mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
243 if (mtag != NULL) {
244 tdbi = (struct tdb_ident *)(mtag + 1);
245 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
246 if (sp == NULL)
247 *error = -EINVAL; /* force silent drop */
248 m_tag_delete(*m, mtag);
249 } else {
250 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
251 error, inp);
252 }
253 /*
254 * There are four return cases:
255 * sp != NULL apply IPsec policy
256 * sp == NULL, error == 0 no IPsec handling needed
257 * sp == NULL, error == -EINVAL discard packet w/o error
258 * sp == NULL, error != 0 discard packet, report error
259 */
260 if (sp != NULL) {
261 /* Loop detection, check if ipsec processing already done */
262 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
263 for (mtag = m_tag_first(*m); mtag != NULL;
264 mtag = m_tag_next(*m, mtag)) {
265 if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
266 continue;
267 if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
268 mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
269 continue;
270 /*
271 * Check if policy has an SA associated with it.
272 * This can happen when an SP has yet to acquire
273 * an SA; e.g. on first reference. If it occurs,
274 * then we let ipsec4_process_packet do its thing.
275 */
276 if (sp->req->sav == NULL)
277 break;
278 tdbi = (struct tdb_ident *)(mtag + 1);
279 if (tdbi->spi == sp->req->sav->spi &&
280 tdbi->proto == sp->req->sav->sah->saidx.proto &&
281 bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
282 sizeof (union sockaddr_union)) == 0) {
283 /*
284 * No IPsec processing is needed, free
285 * reference to SP.
286 *
287 * NB: null pointer to avoid free at
288 * done: below.
289 */
290 KEY_FREESP(&sp), sp = NULL;
291 goto done;
292 }
293 }
294
295 /*
296 * Do delayed checksums now because we send before
297 * this is done in the normal processing path.
298 */
299 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
300 in_delayed_cksum(*m);
301 (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
302 }
303 #ifdef SCTP
304 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP) {
305 struct ip *ip = mtod(*m, struct ip *);
306
307 sctp_delayed_cksum(*m, (uint32_t)(ip->ip_hl << 2));
308 (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP;
309 }
310 #endif
311
312 /* NB: callee frees mbuf */
313 *error = ipsec4_process_packet(*m, sp->req, *flags, 0);
314 if (*error == EJUSTRETURN) {
315 /*
316 * We had a SP with a level of 'use' and no SA. We
317 * will just continue to process the packet without
318 * IPsec processing and return without error.
319 */
320 *error = 0;
321 goto done;
322 }
323 /*
324 * Preserve KAME behaviour: ENOENT can be returned
325 * when an SA acquire is in progress. Don't propagate
326 * this to user-level; it confuses applications.
327 *
328 * XXX this will go away when the SADB is redone.
329 */
330 if (*error == ENOENT)
331 *error = 0;
332 goto reinjected;
333 } else { /* sp == NULL */
334
335 if (*error != 0) {
336 /*
337 * Hack: -EINVAL is used to signal that a packet
338 * should be silently discarded. This is typically
339 * because we asked key management for an SA and
340 * it was delayed (e.g. kicked up to IKE).
341 */
342 if (*error == -EINVAL)
343 *error = 0;
344 goto bad;
345 } else {
346 /* No IPsec processing for this packet. */
347 }
348 }
349 done:
350 if (sp != NULL)
351 KEY_FREESP(&sp);
352 return 0;
353 reinjected:
354 if (sp != NULL)
355 KEY_FREESP(&sp);
356 return -1;
357 bad:
358 if (sp != NULL)
359 KEY_FREESP(&sp);
360 return 1;
361 #endif /* IPSEC */
362 return 0;
363 }
364