ip6_ipsec.c revision 274132 
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/10/sys/netinet6/ip6_ipsec.c 274132 2014-11-05 09:23:29Z ae $");
32
33#include "opt_inet.h"
34#include "opt_inet6.h"
35#include "opt_ipsec.h"
36
37#include <sys/param.h>
38#include <sys/systm.h>
39#include <sys/kernel.h>
40#include <sys/mac.h>
41#include <sys/malloc.h>
42#include <sys/mbuf.h>
43#include <sys/protosw.h>
44#include <sys/socket.h>
45#include <sys/socketvar.h>
46#include <sys/sysctl.h>
47#include <sys/syslog.h>
48
49#include <net/if.h>
50#include <net/route.h>
51#include <net/vnet.h>
52
53#include <netinet/in.h>
54#include <netinet/in_systm.h>
55#include <netinet/in_var.h>
56#include <netinet/ip.h>
57#include <netinet/ip6.h>
58#include <netinet/in_pcb.h>
59#include <netinet/ip_var.h>
60#include <netinet/ip_options.h>
61
62#include <machine/in_cksum.h>
63
64#ifdef IPSEC
65#include <netipsec/ipsec.h>
66#include <netipsec/ipsec6.h>
67#include <netipsec/xform.h>
68#include <netipsec/key.h>
69#ifdef IPSEC_DEBUG
70#include <netipsec/key_debug.h>
71#else
72#define	KEYDEBUG(lev,arg)
73#endif
74#endif /*IPSEC*/
75
76#include <netinet6/ip6_ipsec.h>
77#include <netinet6/ip6_var.h>
78
79extern	struct protosw inet6sw[];
80
81
82#ifdef INET6
83#ifdef IPSEC
84#ifdef IPSEC_FILTERTUNNEL
85static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 1;
86#else
87static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 0;
88#endif
89#define	V_ip6_ipsec6_filtertunnel	VNET(ip6_ipsec6_filtertunnel)
90
91SYSCTL_DECL(_net_inet6_ipsec6);
92SYSCTL_VNET_INT(_net_inet6_ipsec6, OID_AUTO,
93	filtertunnel, CTLFLAG_RW, &VNET_NAME(ip6_ipsec6_filtertunnel),  0,
94	"If set filter packets from an IPsec tunnel.");
95#endif /* IPSEC */
96#endif /* INET6 */
97
98/*
99 * Check if we have to jump over firewall processing for this packet.
100 * Called from ip6_input().
101 * 1 = jump over firewall, 0 = packet goes through firewall.
102 */
103int
104ip6_ipsec_filtertunnel(struct mbuf *m)
105{
106#ifdef IPSEC
107
108	/*
109	 * Bypass packet filtering for packets previously handled by IPsec.
110	 */
111	if (!V_ip6_ipsec6_filtertunnel &&
112	    m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
113		return 1;
114#endif
115	return 0;
116}
117
118/*
119 * Check if this packet has an active SA and needs to be dropped instead
120 * of forwarded.
121 * Called from ip6_input().
122 * 1 = drop packet, 0 = forward packet.
123 */
124int
125ip6_ipsec_fwd(struct mbuf *m)
126{
127#ifdef IPSEC
128	struct m_tag *mtag;
129	struct tdb_ident *tdbi;
130	struct secpolicy *sp;
131	int error;
132	mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
133	if (mtag != NULL) {
134		tdbi = (struct tdb_ident *)(mtag + 1);
135		sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
136	} else {
137		sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
138					   IP_FORWARDING, &error);
139	}
140	if (sp == NULL) {	/* NB: can happen if error */
141		/*XXX error stat???*/
142		DPRINTF(("%s: no SP for forwarding\n", __func__));	/*XXX*/
143		return 1;
144	}
145
146	/*
147	 * Check security policy against packet attributes.
148	 */
149	error = ipsec_in_reject(sp, m);
150	KEY_FREESP(&sp);
151	if (error) {
152		IP6STAT_INC(ip6s_cantforward);
153		return 1;
154	}
155#endif /* IPSEC */
156	return 0;
157}
158
159/*
160 * Check if protocol type doesn't have a further header and do IPSEC
161 * decryption or reject right now.  Protocols with further headers get
162 * their IPSEC treatment within the protocol specific processing.
163 * Called from ip6_input().
164 * 1 = drop packet, 0 = continue processing packet.
165 */
166int
167ip6_ipsec_input(struct mbuf *m, int nxt)
168{
169#ifdef IPSEC
170	struct m_tag *mtag;
171	struct tdb_ident *tdbi;
172	struct secpolicy *sp;
173	int error;
174	/*
175	 * enforce IPsec policy checking if we are seeing last header.
176	 * note that we do not visit this with protocols with pcb layer
177	 * code - like udp/tcp/raw ip.
178	 */
179	if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
180	    ipsec6_in_reject(m, NULL)) {
181
182		/*
183		 * Check if the packet has already had IPsec processing
184		 * done.  If so, then just pass it along.  This tag gets
185		 * set during AH, ESP, etc. input handling, before the
186		 * packet is returned to the ip input queue for delivery.
187		 */
188		mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
189		if (mtag != NULL) {
190			tdbi = (struct tdb_ident *)(mtag + 1);
191			sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
192		} else {
193			sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
194						   IP_FORWARDING, &error);
195		}
196		if (sp != NULL) {
197			/*
198			 * Check security policy against packet attributes.
199			 */
200			error = ipsec_in_reject(sp, m);
201			KEY_FREESP(&sp);
202		} else {
203			/* XXX error stat??? */
204			error = EINVAL;
205			DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
206			return 1;
207		}
208		if (error)
209			return 1;
210	}
211#endif /* IPSEC */
212	return 0;
213}
214
215/*
216 * Called from ip6_output().
217 * 1 = drop packet, 0 = continue processing packet,
218 * -1 = packet was reinjected and stop processing packet
219 */
220
221int
222ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
223    struct ifnet **ifp)
224{
225#ifdef IPSEC
226	struct secpolicy *sp = NULL;
227	struct tdb_ident *tdbi;
228	struct m_tag *mtag;
229	/* XXX int s; */
230	mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
231	if (mtag != NULL) {
232		tdbi = (struct tdb_ident *)(mtag + 1);
233		sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
234		if (sp == NULL)
235			*error = -EINVAL;	/* force silent drop */
236		m_tag_delete(*m, mtag);
237	} else {
238		sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
239					error, inp);
240	}
241
242	/*
243	 * There are four return cases:
244	 *    sp != NULL		    apply IPsec policy
245	 *    sp == NULL, error == 0	    no IPsec handling needed
246	 *    sp == NULL, error == -EINVAL  discard packet w/o error
247	 *    sp == NULL, error != 0	    discard packet, report error
248	 */
249	if (sp != NULL) {
250		/* Loop detection, check if ipsec processing already done */
251		KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
252		for (mtag = m_tag_first(*m); mtag != NULL;
253		     mtag = m_tag_next(*m, mtag)) {
254			if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
255				continue;
256			if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
257			    mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
258				continue;
259			/*
260			 * Check if policy has no SA associated with it.
261			 * This can happen when an SP has yet to acquire
262			 * an SA; e.g. on first reference.  If it occurs,
263			 * then we let ipsec4_process_packet do its thing.
264			 */
265			if (sp->req->sav == NULL)
266				break;
267			tdbi = (struct tdb_ident *)(mtag + 1);
268			if (tdbi->spi == sp->req->sav->spi &&
269			    tdbi->proto == sp->req->sav->sah->saidx.proto &&
270			    bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
271				 sizeof (union sockaddr_union)) == 0) {
272				/*
273				 * No IPsec processing is needed, free
274				 * reference to SP.
275				 *
276				 * NB: null pointer to avoid free at
277				 *     done: below.
278				 */
279				KEY_FREESP(&sp), sp = NULL;
280				goto done;
281			}
282		}
283
284		/*
285		 * Do delayed checksums now because we send before
286		 * this is done in the normal processing path.
287		 */
288#ifdef INET
289		if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
290			in_delayed_cksum(*m);
291			(*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
292		}
293#endif
294		if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
295			in6_delayed_cksum(*m, (*m)->m_pkthdr.len - sizeof(struct ip6_hdr),
296							sizeof(struct ip6_hdr));
297			(*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
298		}
299#ifdef SCTP
300		if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
301			sctp_delayed_cksum(*m, sizeof(struct ip6_hdr));
302			(*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
303		}
304#endif
305
306		/* NB: callee frees mbuf */
307		*error = ipsec6_process_packet(*m, sp->req);
308
309		if (*error == EJUSTRETURN) {
310			/*
311			 * We had a SP with a level of 'use' and no SA. We
312			 * will just continue to process the packet without
313			 * IPsec processing.
314			 */
315			*error = 0;
316			goto done;
317		}
318
319		/*
320		 * Preserve KAME behaviour: ENOENT can be returned
321		 * when an SA acquire is in progress.  Don't propagate
322		 * this to user-level; it confuses applications.
323		 *
324		 * XXX this will go away when the SADB is redone.
325		 */
326		if (*error == ENOENT)
327			*error = 0;
328		goto reinjected;
329	} else {	/* sp == NULL */
330		if (*error != 0) {
331			/*
332			 * Hack: -EINVAL is used to signal that a packet
333			 * should be silently discarded.  This is typically
334			 * because we asked key management for an SA and
335			 * it was delayed (e.g. kicked up to IKE).
336			 */
337			if (*error == -EINVAL)
338				*error = 0;
339			goto bad;
340		} else {
341			/* No IPsec processing for this packet. */
342		}
343	}
344done:
345	if (sp != NULL)
346		KEY_FREESP(&sp);
347	return 0;
348reinjected:
349	if (sp != NULL)
350		KEY_FREESP(&sp);
351	return -1;
352bad:
353	if (sp != NULL)
354		KEY_FREESP(&sp);
355	return 1;
356#endif /* IPSEC */
357	return 0;
358}
359
360#if 0
361/*
362 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
363 * Called from ip_forward().
364 * Returns MTU suggestion for ICMP needfrag reply.
365 */
366int
367ip6_ipsec_mtu(struct mbuf *m)
368{
369	int mtu = 0;
370	/*
371	 * If the packet is routed over IPsec tunnel, tell the
372	 * originator the tunnel MTU.
373	 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
374	 * XXX quickhack!!!
375	 */
376#ifdef IPSEC
377	struct secpolicy *sp = NULL;
378	int ipsecerror;
379	int ipsechdr;
380	struct route *ro;
381	sp = ipsec_getpolicybyaddr(m,
382				   IPSEC_DIR_OUTBOUND,
383				   IP_FORWARDING,
384				   &ipsecerror);
385	if (sp != NULL) {
386		/* count IPsec header size */
387		ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
388
389		/*
390		 * find the correct route for outer IPv4
391		 * header, compute tunnel MTU.
392		 */
393		if (sp->req != NULL &&
394		    sp->req->sav != NULL &&
395		    sp->req->sav->sah != NULL) {
396			ro = &sp->req->sav->sah->route_cache.sa_route;
397			if (ro->ro_rt && ro->ro_rt->rt_ifp) {
398				mtu = ro->ro_rt->rt_mtu ? ro->ro_rt->rt_mtu :
399				    ro->ro_rt->rt_ifp->if_mtu;
400				mtu -= ipsechdr;
401			}
402		}
403		KEY_FREESP(&sp);
404	}
405#endif /* IPSEC */
406	/* XXX else case missing. */
407	return mtu;
408}
409#endif
410