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: releng/10.3/sys/netinet6/ip6_ipsec.c 283901 2015-06-02 03:14:42Z 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/vnet.h>
51
52#include <netinet/in.h>
53#include <netinet/in_systm.h>
54#include <netinet/in_var.h>
55#include <netinet/ip.h>
56#include <netinet/ip6.h>
57#include <netinet/in_pcb.h>
58#include <netinet/ip_var.h>
59#include <netinet/ip_options.h>
60
61#include <machine/in_cksum.h>
62
63#ifdef IPSEC
64#include <netipsec/ipsec.h>
65#include <netipsec/ipsec6.h>
66#include <netipsec/xform.h>
67#include <netipsec/key.h>
68#ifdef IPSEC_DEBUG
69#include <netipsec/key_debug.h>
70#else
71#define	KEYDEBUG(lev,arg)
72#endif
73#endif /*IPSEC*/
74
75#include <netinet6/ip6_ipsec.h>
76#include <netinet6/ip6_var.h>
77
78extern	struct protosw inet6sw[];
79
80
81#ifdef INET6
82#ifdef IPSEC
83#ifdef IPSEC_FILTERTUNNEL
84static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 1;
85#else
86static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 0;
87#endif
88#define	V_ip6_ipsec6_filtertunnel	VNET(ip6_ipsec6_filtertunnel)
89
90SYSCTL_DECL(_net_inet6_ipsec6);
91SYSCTL_VNET_INT(_net_inet6_ipsec6, OID_AUTO,
92	filtertunnel, CTLFLAG_RW, &VNET_NAME(ip6_ipsec6_filtertunnel),  0,
93	"If set filter packets from an IPsec tunnel.");
94#endif /* IPSEC */
95#endif /* INET6 */
96
97/*
98 * Check if we have to jump over firewall processing for this packet.
99 * Called from ip6_input().
100 * 1 = jump over firewall, 0 = packet goes through firewall.
101 */
102int
103ip6_ipsec_filtertunnel(struct mbuf *m)
104{
105#ifdef IPSEC
106
107	/*
108	 * Bypass packet filtering for packets previously handled by IPsec.
109	 */
110	if (!V_ip6_ipsec6_filtertunnel &&
111	    m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
112		return 1;
113#endif
114	return 0;
115}
116
117/*
118 * Check if this packet has an active SA and needs to be dropped instead
119 * of forwarded.
120 * Called from ip6_input().
121 * 1 = drop packet, 0 = forward packet.
122 */
123int
124ip6_ipsec_fwd(struct mbuf *m)
125{
126#ifdef IPSEC
127	struct m_tag *mtag;
128	struct tdb_ident *tdbi;
129	struct secpolicy *sp;
130	int error;
131	mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
132	if (mtag != NULL) {
133		tdbi = (struct tdb_ident *)(mtag + 1);
134		sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
135	} else {
136		sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
137					   IP_FORWARDING, &error);
138	}
139	if (sp == NULL) {	/* NB: can happen if error */
140		/*XXX error stat???*/
141		DPRINTF(("%s: no SP for forwarding\n", __func__));	/*XXX*/
142		return 1;
143	}
144
145	/*
146	 * Check security policy against packet attributes.
147	 */
148	error = ipsec_in_reject(sp, m);
149	KEY_FREESP(&sp);
150	if (error) {
151		IP6STAT_INC(ip6s_cantforward);
152		return 1;
153	}
154#endif /* IPSEC */
155	return 0;
156}
157
158/*
159 * Check if protocol type doesn't have a further header and do IPSEC
160 * decryption or reject right now.  Protocols with further headers get
161 * their IPSEC treatment within the protocol specific processing.
162 * Called from ip6_input().
163 * 1 = drop packet, 0 = continue processing packet.
164 */
165int
166ip6_ipsec_input(struct mbuf *m, int nxt)
167{
168#ifdef IPSEC
169	struct m_tag *mtag;
170	struct tdb_ident *tdbi;
171	struct secpolicy *sp;
172	int error;
173	/*
174	 * enforce IPsec policy checking if we are seeing last header.
175	 * note that we do not visit this with protocols with pcb layer
176	 * code - like udp/tcp/raw ip.
177	 */
178	if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
179	    ipsec6_in_reject(m, NULL)) {
180
181		/*
182		 * Check if the packet has already had IPsec processing
183		 * done.  If so, then just pass it along.  This tag gets
184		 * set during AH, ESP, etc. input handling, before the
185		 * packet is returned to the ip input queue for delivery.
186		 */
187		mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
188		if (mtag != NULL) {
189			tdbi = (struct tdb_ident *)(mtag + 1);
190			sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
191		} else {
192			sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
193						   IP_FORWARDING, &error);
194		}
195		if (sp != NULL) {
196			/*
197			 * Check security policy against packet attributes.
198			 */
199			error = ipsec_in_reject(sp, m);
200			KEY_FREESP(&sp);
201		} else {
202			/* XXX error stat??? */
203			error = EINVAL;
204			DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
205			return 1;
206		}
207		if (error)
208			return 1;
209	}
210#endif /* IPSEC */
211	return 0;
212}
213
214/*
215 * Called from ip6_output().
216 * 1 = drop packet, 0 = continue processing packet,
217 * -1 = packet was reinjected and stop processing packet
218 */
219
220int
221ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
222    struct ifnet **ifp)
223{
224#ifdef IPSEC
225	struct secpolicy *sp = NULL;
226	struct tdb_ident *tdbi;
227	struct m_tag *mtag;
228	/* XXX int s; */
229	mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
230	if (mtag != NULL) {
231		tdbi = (struct tdb_ident *)(mtag + 1);
232		sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
233		if (sp == NULL)
234			*error = -EINVAL;	/* force silent drop */
235		m_tag_delete(*m, mtag);
236	} else {
237		sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
238					error, inp);
239	}
240
241	/*
242	 * There are four return cases:
243	 *    sp != NULL		    apply IPsec policy
244	 *    sp == NULL, error == 0	    no IPsec handling needed
245	 *    sp == NULL, error == -EINVAL  discard packet w/o error
246	 *    sp == NULL, error != 0	    discard packet, report error
247	 */
248	if (sp != NULL) {
249		/* Loop detection, check if ipsec processing already done */
250		KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
251		for (mtag = m_tag_first(*m); mtag != NULL;
252		     mtag = m_tag_next(*m, mtag)) {
253			if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
254				continue;
255			if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
256			    mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
257				continue;
258			/*
259			 * Check if policy has no SA associated with it.
260			 * This can happen when an SP has yet to acquire
261			 * an SA; e.g. on first reference.  If it occurs,
262			 * then we let ipsec4_process_packet do its thing.
263			 */
264			if (sp->req->sav == NULL)
265				break;
266			tdbi = (struct tdb_ident *)(mtag + 1);
267			if (tdbi->spi == sp->req->sav->spi &&
268			    tdbi->proto == sp->req->sav->sah->saidx.proto &&
269			    bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
270				 sizeof (union sockaddr_union)) == 0) {
271				/*
272				 * No IPsec processing is needed, free
273				 * reference to SP.
274				 */
275				goto done;
276			}
277		}
278
279		/*
280		 * Do delayed checksums now because we send before
281		 * this is done in the normal processing path.
282		 */
283#ifdef INET
284		if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
285			in_delayed_cksum(*m);
286			(*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
287		}
288#endif
289		if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
290			in6_delayed_cksum(*m, (*m)->m_pkthdr.len - sizeof(struct ip6_hdr),
291							sizeof(struct ip6_hdr));
292			(*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
293		}
294#ifdef SCTP
295		if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
296			sctp_delayed_cksum(*m, sizeof(struct ip6_hdr));
297			(*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
298		}
299#endif
300
301		/* NB: callee frees mbuf */
302		*error = ipsec6_process_packet(*m, sp->req);
303
304		if (*error == EJUSTRETURN) {
305			/*
306			 * We had a SP with a level of 'use' and no SA. We
307			 * will just continue to process the packet without
308			 * IPsec processing.
309			 */
310			*error = 0;
311			goto done;
312		}
313
314		/*
315		 * Preserve KAME behaviour: ENOENT can be returned
316		 * when an SA acquire is in progress.  Don't propagate
317		 * this to user-level; it confuses applications.
318		 *
319		 * XXX this will go away when the SADB is redone.
320		 */
321		if (*error == ENOENT)
322			*error = 0;
323		goto reinjected;
324	} else {	/* sp == NULL */
325		if (*error != 0) {
326			/*
327			 * Hack: -EINVAL is used to signal that a packet
328			 * should be silently discarded.  This is typically
329			 * because we asked key management for an SA and
330			 * it was delayed (e.g. kicked up to IKE).
331			 */
332			if (*error == -EINVAL)
333				*error = 0;
334			goto bad;
335		} else {
336			/* No IPsec processing for this packet. */
337		}
338	}
339done:
340	if (sp != NULL)
341		KEY_FREESP(&sp);
342	return 0;
343reinjected:
344	if (sp != NULL)
345		KEY_FREESP(&sp);
346	return -1;
347bad:
348	if (sp != NULL)
349		KEY_FREESP(&sp);
350	return 1;
351#endif /* IPSEC */
352	return 0;
353}
354
355#if 0
356/*
357 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
358 * Called from ip_forward().
359 * Returns MTU suggestion for ICMP needfrag reply.
360 */
361int
362ip6_ipsec_mtu(struct mbuf *m)
363{
364	int mtu = 0;
365	/*
366	 * If the packet is routed over IPsec tunnel, tell the
367	 * originator the tunnel MTU.
368	 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
369	 * XXX quickhack!!!
370	 */
371#ifdef IPSEC
372	struct secpolicy *sp = NULL;
373	int ipsecerror;
374	int ipsechdr;
375	struct route *ro;
376	sp = ipsec_getpolicybyaddr(m,
377				   IPSEC_DIR_OUTBOUND,
378				   IP_FORWARDING,
379				   &ipsecerror);
380	if (sp != NULL) {
381		/* count IPsec header size */
382		ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
383
384		/*
385		 * find the correct route for outer IPv4
386		 * header, compute tunnel MTU.
387		 */
388		if (sp->req != NULL &&
389		    sp->req->sav != NULL &&
390		    sp->req->sav->sah != NULL) {
391			ro = &sp->req->sav->sah->route_cache.sa_route;
392			if (ro->ro_rt && ro->ro_rt->rt_ifp) {
393				mtu = ro->ro_rt->rt_mtu ? ro->ro_rt->rt_mtu :
394				    ro->ro_rt->rt_ifp->if_mtu;
395				mtu -= ipsechdr;
396			}
397		}
398		KEY_FREESP(&sp);
399	}
400#endif /* IPSEC */
401	/* XXX else case missing. */
402	return mtu;
403}
404#endif
405