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_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#if defined(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 s, error;
132	mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
133	s = splnet();
134	if (mtag != NULL) {
135		tdbi = (struct tdb_ident *)(mtag + 1);
136		sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
137	} else {
138		sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
139					   IP_FORWARDING, &error);
140	}
141	if (sp == NULL) {	/* NB: can happen if error */
142		splx(s);
143		/*XXX error stat???*/
144		DPRINTF(("%s: no SP for forwarding\n", __func__));	/*XXX*/
145		return 1;
146	}
147
148	/*
149	 * Check security policy against packet attributes.
150	 */
151	error = ipsec_in_reject(sp, m);
152	KEY_FREESP(&sp);
153	splx(s);
154	if (error) {
155		IP6STAT_INC(ip6s_cantforward);
156		return 1;
157	}
158#endif /* IPSEC */
159	return 0;
160}
161
162/*
163 * Check if protocol type doesn't have a further header and do IPSEC
164 * decryption or reject right now.  Protocols with further headers get
165 * their IPSEC treatment within the protocol specific processing.
166 * Called from ip6_input().
167 * 1 = drop packet, 0 = continue processing packet.
168 */
169int
170ip6_ipsec_input(struct mbuf *m, int nxt)
171{
172#ifdef IPSEC
173	struct m_tag *mtag;
174	struct tdb_ident *tdbi;
175	struct secpolicy *sp;
176	int s, error;
177	/*
178	 * enforce IPsec policy checking if we are seeing last header.
179	 * note that we do not visit this with protocols with pcb layer
180	 * code - like udp/tcp/raw ip.
181	 */
182	if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
183	    ipsec6_in_reject(m, NULL)) {
184
185		/*
186		 * Check if the packet has already had IPsec processing
187		 * done.  If so, then just pass it along.  This tag gets
188		 * set during AH, ESP, etc. input handling, before the
189		 * packet is returned to the ip input queue for delivery.
190		 */
191		mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
192		s = splnet();
193		if (mtag != NULL) {
194			tdbi = (struct tdb_ident *)(mtag + 1);
195			sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
196		} else {
197			sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
198						   IP_FORWARDING, &error);
199		}
200		if (sp != NULL) {
201			/*
202			 * Check security policy against packet attributes.
203			 */
204			error = ipsec_in_reject(sp, m);
205			KEY_FREESP(&sp);
206		} else {
207			/* XXX error stat??? */
208			error = EINVAL;
209			DPRINTF(("%s: no SP, packet discarded\n", __func__));/*XXX*/
210			return 1;
211		}
212		splx(s);
213		if (error)
214			return 1;
215	}
216#endif /* IPSEC */
217	return 0;
218}
219
220/*
221 * Called from ip6_output().
222 * 1 = drop packet, 0 = continue processing packet,
223 * -1 = packet was reinjected and stop processing packet
224 */
225
226int
227ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
228    struct ifnet **ifp, struct secpolicy **sp)
229{
230#ifdef IPSEC
231	struct tdb_ident *tdbi;
232	struct m_tag *mtag;
233	/* XXX int s; */
234	if (sp == NULL)
235		return 1;
236	mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
237	if (mtag != NULL) {
238		tdbi = (struct tdb_ident *)(mtag + 1);
239		*sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
240		if (*sp == NULL)
241			*error = -EINVAL;	/* force silent drop */
242		m_tag_delete(*m, mtag);
243	} else {
244		*sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
245					error, inp);
246	}
247
248	/*
249	 * There are four return cases:
250	 *    sp != NULL		    apply IPsec policy
251	 *    sp == NULL, error == 0	    no IPsec handling needed
252	 *    sp == NULL, error == -EINVAL  discard packet w/o error
253	 *    sp == NULL, error != 0	    discard packet, report error
254	 */
255	if (*sp != NULL) {
256		/* Loop detection, check if ipsec processing already done */
257		KASSERT((*sp)->req != NULL, ("ip_output: no ipsec request"));
258		for (mtag = m_tag_first(*m); mtag != NULL;
259		     mtag = m_tag_next(*m, mtag)) {
260			if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
261				continue;
262			if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
263			    mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
264				continue;
265			/*
266			 * Check if policy has no SA associated with it.
267			 * This can happen when an SP has yet to acquire
268			 * an SA; e.g. on first reference.  If it occurs,
269			 * then we let ipsec4_process_packet do its thing.
270			 */
271			if ((*sp)->req->sav == NULL)
272				break;
273			tdbi = (struct tdb_ident *)(mtag + 1);
274			if (tdbi->spi == (*sp)->req->sav->spi &&
275			    tdbi->proto == (*sp)->req->sav->sah->saidx.proto &&
276			    bcmp(&tdbi->dst, &(*sp)->req->sav->sah->saidx.dst,
277				 sizeof (union sockaddr_union)) == 0) {
278				/*
279				 * No IPsec processing is needed, free
280				 * reference to SP.
281				 *
282				 * NB: null pointer to avoid free at
283				 *     done: below.
284				 */
285				KEY_FREESP(sp), *sp = NULL;
286				/* XXX splx(s); */
287				goto done;
288			}
289		}
290
291		/*
292		 * Do delayed checksums now because we send before
293		 * this is done in the normal processing path.
294		 * For IPv6 we do delayed checksums in ip6_output.c.
295		 */
296#ifdef INET
297		if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
298			ipseclog((LOG_DEBUG,
299			    "%s: we do not support IPv4 over IPv6", __func__));
300			in_delayed_cksum(*m);
301			(*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
302		}
303#endif
304
305		/*
306		 * Preserve KAME behaviour: ENOENT can be returned
307		 * when an SA acquire is in progress.  Don't propagate
308		 * this to user-level; it confuses applications.
309		 *
310		 * XXX this will go away when the SADB is redone.
311		 */
312		if (*error == ENOENT)
313			*error = 0;
314		goto do_ipsec;
315	} else {	/* sp == NULL */
316		if (*error != 0) {
317			/*
318			 * Hack: -EINVAL is used to signal that a packet
319			 * should be silently discarded.  This is typically
320			 * because we asked key management for an SA and
321			 * it was delayed (e.g. kicked up to IKE).
322			 */
323			if (*error == -EINVAL)
324				*error = 0;
325			goto bad;
326		} else {
327			/* No IPsec processing for this packet. */
328		}
329	}
330done:
331	return 0;
332do_ipsec:
333	return -1;
334bad:
335	return 1;
336#endif /* IPSEC */
337	return 0;
338}
339
340#if 0
341/*
342 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
343 * Called from ip_forward().
344 * Returns MTU suggestion for ICMP needfrag reply.
345 */
346int
347ip6_ipsec_mtu(struct mbuf *m)
348{
349	int mtu = 0;
350	/*
351	 * If the packet is routed over IPsec tunnel, tell the
352	 * originator the tunnel MTU.
353	 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
354	 * XXX quickhack!!!
355	 */
356#ifdef IPSEC
357	struct secpolicy *sp = NULL;
358	int ipsecerror;
359	int ipsechdr;
360	struct route *ro;
361	sp = ipsec_getpolicybyaddr(m,
362				   IPSEC_DIR_OUTBOUND,
363				   IP_FORWARDING,
364				   &ipsecerror);
365	if (sp != NULL) {
366		/* count IPsec header size */
367		ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
368
369		/*
370		 * find the correct route for outer IPv4
371		 * header, compute tunnel MTU.
372		 */
373		if (sp->req != NULL &&
374		    sp->req->sav != NULL &&
375		    sp->req->sav->sah != NULL) {
376			ro = &sp->req->sav->sah->route_cache.sa_route;
377			if (ro->ro_rt && ro->ro_rt->rt_ifp) {
378				mtu =
379				    ro->ro_rt->rt_rmx.rmx_mtu ?
380				    ro->ro_rt->rt_rmx.rmx_mtu :
381				    ro->ro_rt->rt_ifp->if_mtu;
382				mtu -= ipsechdr;
383			}
384		}
385		KEY_FREESP(&sp);
386	}
387#endif /* IPSEC */
388	/* XXX else case missing. */
389	return mtu;
390}
391#endif
392