xform_ipip.c revision 134391 
1/*	$FreeBSD: head/sys/netipsec/xform_ipip.c 134391 2004-08-27 18:33:08Z andre $	*/
2/*	$OpenBSD: ip_ipip.c,v 1.25 2002/06/10 18:04:55 itojun Exp $ */
3/*
4 * The authors of this code are John Ioannidis (ji@tla.org),
5 * Angelos D. Keromytis (kermit@csd.uch.gr) and
6 * Niels Provos (provos@physnet.uni-hamburg.de).
7 *
8 * The original version of this code was written by John Ioannidis
9 * for BSD/OS in Athens, Greece, in November 1995.
10 *
11 * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
12 * by Angelos D. Keromytis.
13 *
14 * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
15 * and Niels Provos.
16 *
17 * Additional features in 1999 by Angelos D. Keromytis.
18 *
19 * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
20 * Angelos D. Keromytis and Niels Provos.
21 * Copyright (c) 2001, Angelos D. Keromytis.
22 *
23 * Permission to use, copy, and modify this software with or without fee
24 * is hereby granted, provided that this entire notice is included in
25 * all copies of any software which is or includes a copy or
26 * modification of this software.
27 * You may use this code under the GNU public license if you so wish. Please
28 * contribute changes back to the authors under this freer than GPL license
29 * so that we may further the use of strong encryption without limitations to
30 * all.
31 *
32 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
33 * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
34 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
35 * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
36 * PURPOSE.
37 */
38
39/*
40 * IP-inside-IP processing
41 */
42#include "opt_inet.h"
43#include "opt_inet6.h"
44
45#include <sys/param.h>
46#include <sys/systm.h>
47#include <sys/mbuf.h>
48#include <sys/socket.h>
49#include <sys/kernel.h>
50#include <sys/protosw.h>
51#include <sys/sysctl.h>
52
53#include <net/if.h>
54#include <net/route.h>
55#include <net/netisr.h>
56
57#include <netinet/in.h>
58#include <netinet/in_systm.h>
59#include <netinet/in_var.h>
60#include <netinet/ip.h>
61#include <netinet/ip_ecn.h>
62#include <netinet/ip_var.h>
63#include <netinet/ip_encap.h>
64#include <netinet/ipprotosw.h>
65
66#include <netipsec/ipsec.h>
67#include <netipsec/xform.h>
68
69#include <netipsec/ipip_var.h>
70
71#ifdef MROUTING
72#include <netinet/ip_mroute.h>
73#endif
74
75#ifdef INET6
76#include <netinet/ip6.h>
77#include <netipsec/ipsec6.h>
78#include <netinet6/ip6_ecn.h>
79#include <netinet6/in6_var.h>
80#include <netinet6/ip6protosw.h>
81#endif
82
83#include <netipsec/key.h>
84#include <netipsec/key_debug.h>
85
86#include <machine/stdarg.h>
87
88/*
89 * We can control the acceptance of IP4 packets by altering the sysctl
90 * net.inet.ipip.allow value.  Zero means drop them, all else is acceptance.
91 */
92int	ipip_allow = 0;
93struct	ipipstat ipipstat;
94
95SYSCTL_DECL(_net_inet_ipip);
96SYSCTL_INT(_net_inet_ipip, OID_AUTO,
97	ipip_allow,	CTLFLAG_RW,	&ipip_allow,	0, "");
98SYSCTL_STRUCT(_net_inet_ipip, IPSECCTL_STATS,
99	stats,		CTLFLAG_RD,	&ipipstat,	ipipstat, "");
100
101/* XXX IPCOMP */
102#define	M_IPSEC	(M_AUTHIPHDR|M_AUTHIPDGM|M_DECRYPTED)
103
104static void _ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp);
105
106#ifdef INET6
107/*
108 * Really only a wrapper for ipip_input(), for use with IPv6.
109 */
110int
111ip4_input6(struct mbuf **m, int *offp, int proto)
112{
113#if 0
114	/* If we do not accept IP-in-IP explicitly, drop.  */
115	if (!ipip_allow && ((*m)->m_flags & M_IPSEC) == 0) {
116		DPRINTF(("%s: dropped due to policy\n", __func__));
117		ipipstat.ipips_pdrops++;
118		m_freem(*m);
119		return IPPROTO_DONE;
120	}
121#endif
122	_ipip_input(*m, *offp, NULL);
123	return IPPROTO_DONE;
124}
125#endif /* INET6 */
126
127#ifdef INET
128/*
129 * Really only a wrapper for ipip_input(), for use with IPv4.
130 */
131void
132ip4_input(struct mbuf *m, ...)
133{
134	va_list ap;
135	int iphlen;
136
137#if 0
138	/* If we do not accept IP-in-IP explicitly, drop.  */
139	if (!ipip_allow && (m->m_flags & M_IPSEC) == 0) {
140		DPRINTF(("%s: dropped due to policy\n", __func__));
141		ipipstat.ipips_pdrops++;
142		m_freem(m);
143		return;
144	}
145#endif
146	va_start(ap, m);
147	iphlen = va_arg(ap, int);
148	va_end(ap);
149
150	_ipip_input(m, iphlen, NULL);
151}
152#endif /* INET */
153
154/*
155 * ipip_input gets called when we receive an IP{46} encapsulated packet,
156 * either because we got it at a real interface, or because AH or ESP
157 * were being used in tunnel mode (in which case the rcvif element will
158 * contain the address of the encX interface associated with the tunnel.
159 */
160
161static void
162_ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp)
163{
164	register struct sockaddr_in *sin;
165	register struct ifnet *ifp;
166	register struct ifaddr *ifa;
167	struct ip *ipo;
168#ifdef INET6
169	register struct sockaddr_in6 *sin6;
170	struct ip6_hdr *ip6 = NULL;
171	u_int8_t itos;
172#endif
173	u_int8_t nxt;
174	int isr;
175	u_int8_t otos;
176	u_int8_t v;
177	int hlen;
178
179	ipipstat.ipips_ipackets++;
180
181	m_copydata(m, 0, 1, &v);
182
183	switch (v >> 4) {
184#ifdef INET
185        case 4:
186		hlen = sizeof(struct ip);
187		break;
188#endif /* INET */
189#ifdef INET6
190        case 6:
191		hlen = sizeof(struct ip6_hdr);
192		break;
193#endif
194        default:
195		ipipstat.ipips_family++;
196		m_freem(m);
197		return /* EAFNOSUPPORT */;
198	}
199
200	/* Bring the IP header in the first mbuf, if not there already */
201	if (m->m_len < hlen) {
202		if ((m = m_pullup(m, hlen)) == NULL) {
203			DPRINTF(("%s: m_pullup (1) failed\n", __func__));
204			ipipstat.ipips_hdrops++;
205			return;
206		}
207	}
208
209	ipo = mtod(m, struct ip *);
210
211#ifdef MROUTING
212	if (ipo->ip_v == IPVERSION && ipo->ip_p == IPPROTO_IPV4) {
213		if (IN_MULTICAST(((struct ip *)((char *) ipo + iphlen))->ip_dst.s_addr)) {
214			ipip_mroute_input (m, iphlen);
215			return;
216		}
217	}
218#endif /* MROUTING */
219
220	/* Keep outer ecn field. */
221	switch (v >> 4) {
222#ifdef INET
223	case 4:
224		otos = ipo->ip_tos;
225		break;
226#endif /* INET */
227#ifdef INET6
228	case 6:
229		otos = (ntohl(mtod(m, struct ip6_hdr *)->ip6_flow) >> 20) & 0xff;
230		break;
231#endif
232	default:
233		panic("ipip_input: unknown ip version %u (outer)", v>>4);
234	}
235
236	/* Remove outer IP header */
237	m_adj(m, iphlen);
238
239	/* Sanity check */
240	if (m->m_pkthdr.len < sizeof(struct ip))  {
241		ipipstat.ipips_hdrops++;
242		m_freem(m);
243		return;
244	}
245
246	m_copydata(m, 0, 1, &v);
247
248	switch (v >> 4) {
249#ifdef INET
250        case 4:
251		hlen = sizeof(struct ip);
252		break;
253#endif /* INET */
254
255#ifdef INET6
256        case 6:
257		hlen = sizeof(struct ip6_hdr);
258		break;
259#endif
260	default:
261		ipipstat.ipips_family++;
262		m_freem(m);
263		return; /* EAFNOSUPPORT */
264	}
265
266	/*
267	 * Bring the inner IP header in the first mbuf, if not there already.
268	 */
269	if (m->m_len < hlen) {
270		if ((m = m_pullup(m, hlen)) == NULL) {
271			DPRINTF(("%s: m_pullup (2) failed\n", __func__));
272			ipipstat.ipips_hdrops++;
273			return;
274		}
275	}
276
277	/*
278	 * RFC 1853 specifies that the inner TTL should not be touched on
279	 * decapsulation. There's no reason this comment should be here, but
280	 * this is as good as any a position.
281	 */
282
283	/* Some sanity checks in the inner IP header */
284	switch (v >> 4) {
285#ifdef INET
286    	case 4:
287                ipo = mtod(m, struct ip *);
288                nxt = ipo->ip_p;
289		ip_ecn_egress(ip4_ipsec_ecn, &otos, &ipo->ip_tos);
290                break;
291#endif /* INET */
292#ifdef INET6
293    	case 6:
294                ip6 = (struct ip6_hdr *) ipo;
295                nxt = ip6->ip6_nxt;
296		itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
297		ip_ecn_egress(ip6_ipsec_ecn, &otos, &itos);
298		ip6->ip6_flow &= ~htonl(0xff << 20);
299		ip6->ip6_flow |= htonl((u_int32_t) itos << 20);
300                break;
301#endif
302	default:
303		panic("ipip_input: unknown ip version %u (inner)", v>>4);
304	}
305
306	/* Check for local address spoofing. */
307	if ((m->m_pkthdr.rcvif == NULL ||
308	    !(m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK)) &&
309	    ipip_allow != 2) {
310	    	IFNET_RLOCK();
311		TAILQ_FOREACH(ifp, &ifnet, if_link) {
312			TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
313#ifdef INET
314				if (ipo) {
315					if (ifa->ifa_addr->sa_family !=
316					    AF_INET)
317						continue;
318
319					sin = (struct sockaddr_in *) ifa->ifa_addr;
320
321					if (sin->sin_addr.s_addr ==
322					    ipo->ip_src.s_addr)	{
323						ipipstat.ipips_spoof++;
324						m_freem(m);
325						IFNET_RUNLOCK();
326						return;
327					}
328				}
329#endif /* INET */
330
331#ifdef INET6
332				if (ip6) {
333					if (ifa->ifa_addr->sa_family !=
334					    AF_INET6)
335						continue;
336
337					sin6 = (struct sockaddr_in6 *) ifa->ifa_addr;
338
339					if (IN6_ARE_ADDR_EQUAL(&sin6->sin6_addr, &ip6->ip6_src)) {
340						ipipstat.ipips_spoof++;
341						m_freem(m);
342						IFNET_RUNLOCK();
343						return;
344					}
345
346				}
347#endif /* INET6 */
348			}
349		}
350		IFNET_RUNLOCK();
351	}
352
353	/* Statistics */
354	ipipstat.ipips_ibytes += m->m_pkthdr.len - iphlen;
355
356	/*
357	 * Interface pointer stays the same; if no IPsec processing has
358	 * been done (or will be done), this will point to a normal
359	 * interface. Otherwise, it'll point to an enc interface, which
360	 * will allow a packet filter to distinguish between secure and
361	 * untrusted packets.
362	 */
363
364	switch (v >> 4) {
365#ifdef INET
366	case 4:
367		isr = NETISR_IP;
368		break;
369#endif
370#ifdef INET6
371	case 6:
372		isr = NETISR_IPV6;
373		break;
374#endif
375	default:
376		panic("%s: bogus ip version %u", __func__, v>>4);
377	}
378
379	if (netisr_queue(isr, m)) {	/* (0) on success. */
380		ipipstat.ipips_qfull++;
381		DPRINTF(("%s: packet dropped because of full queue\n",
382			__func__));
383	}
384}
385
386int
387ipip_output(
388	struct mbuf *m,
389	struct ipsecrequest *isr,
390	struct mbuf **mp,
391	int skip,
392	int protoff
393)
394{
395	struct secasvar *sav;
396	u_int8_t tp, otos;
397	struct secasindex *saidx;
398	int error;
399#ifdef INET
400	u_int8_t itos;
401	struct ip *ipo;
402#endif /* INET */
403#ifdef INET6
404	struct ip6_hdr *ip6, *ip6o;
405#endif /* INET6 */
406
407	IPSEC_SPLASSERT_SOFTNET(__func__);
408
409	sav = isr->sav;
410	IPSEC_ASSERT(sav != NULL, ("null SA"));
411	IPSEC_ASSERT(sav->sah != NULL, ("null SAH"));
412
413	/* XXX Deal with empty TDB source/destination addresses. */
414
415	m_copydata(m, 0, 1, &tp);
416	tp = (tp >> 4) & 0xff;  /* Get the IP version number. */
417
418	saidx = &sav->sah->saidx;
419	switch (saidx->dst.sa.sa_family) {
420#ifdef INET
421	case AF_INET:
422		if (saidx->src.sa.sa_family != AF_INET ||
423		    saidx->src.sin.sin_addr.s_addr == INADDR_ANY ||
424		    saidx->dst.sin.sin_addr.s_addr == INADDR_ANY) {
425			DPRINTF(("%s: unspecified tunnel endpoint "
426			    "address in SA %s/%08lx\n", __func__,
427			    ipsec_address(&saidx->dst),
428			    (u_long) ntohl(sav->spi)));
429			ipipstat.ipips_unspec++;
430			error = EINVAL;
431			goto bad;
432		}
433
434		M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
435		if (m == 0) {
436			DPRINTF(("%s: M_PREPEND failed\n", __func__));
437			ipipstat.ipips_hdrops++;
438			error = ENOBUFS;
439			goto bad;
440		}
441
442		ipo = mtod(m, struct ip *);
443
444		ipo->ip_v = IPVERSION;
445		ipo->ip_hl = 5;
446		ipo->ip_len = htons(m->m_pkthdr.len);
447		ipo->ip_ttl = ip_defttl;
448		ipo->ip_sum = 0;
449		ipo->ip_src = saidx->src.sin.sin_addr;
450		ipo->ip_dst = saidx->dst.sin.sin_addr;
451
452		ipo->ip_id = ip_newid();
453
454		/* If the inner protocol is IP... */
455		if (tp == IPVERSION) {
456			/* Save ECN notification */
457			m_copydata(m, sizeof(struct ip) +
458			    offsetof(struct ip, ip_tos),
459			    sizeof(u_int8_t), (caddr_t) &itos);
460
461			ipo->ip_p = IPPROTO_IPIP;
462
463			/*
464			 * We should be keeping tunnel soft-state and
465			 * send back ICMPs if needed.
466			 */
467			m_copydata(m, sizeof(struct ip) +
468			    offsetof(struct ip, ip_off),
469			    sizeof(u_int16_t), (caddr_t) &ipo->ip_off);
470			ipo->ip_off = ntohs(ipo->ip_off);
471			ipo->ip_off &= ~(IP_DF | IP_MF | IP_OFFMASK);
472			ipo->ip_off = htons(ipo->ip_off);
473		}
474#ifdef INET6
475		else if (tp == (IPV6_VERSION >> 4)) {
476			u_int32_t itos32;
477
478			/* Save ECN notification. */
479			m_copydata(m, sizeof(struct ip) +
480			    offsetof(struct ip6_hdr, ip6_flow),
481			    sizeof(u_int32_t), (caddr_t) &itos32);
482			itos = ntohl(itos32) >> 20;
483			ipo->ip_p = IPPROTO_IPV6;
484			ipo->ip_off = 0;
485		}
486#endif /* INET6 */
487		else {
488			goto nofamily;
489		}
490
491		otos = 0;
492		ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
493		ipo->ip_tos = otos;
494		break;
495#endif /* INET */
496
497#ifdef INET6
498	case AF_INET6:
499		if (IN6_IS_ADDR_UNSPECIFIED(&saidx->dst.sin6.sin6_addr) ||
500		    saidx->src.sa.sa_family != AF_INET6 ||
501		    IN6_IS_ADDR_UNSPECIFIED(&saidx->src.sin6.sin6_addr)) {
502			DPRINTF(("%s: unspecified tunnel endpoint "
503			    "address in SA %s/%08lx\n", __func__,
504			    ipsec_address(&saidx->dst),
505			    (u_long) ntohl(sav->spi)));
506			ipipstat.ipips_unspec++;
507			error = ENOBUFS;
508			goto bad;
509		}
510
511		/* scoped address handling */
512		ip6 = mtod(m, struct ip6_hdr *);
513		if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
514			ip6->ip6_src.s6_addr16[1] = 0;
515		if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
516			ip6->ip6_dst.s6_addr16[1] = 0;
517
518		M_PREPEND(m, sizeof(struct ip6_hdr), M_DONTWAIT);
519		if (m == 0) {
520			DPRINTF(("%s: M_PREPEND failed\n", __func__));
521			ipipstat.ipips_hdrops++;
522			error = ENOBUFS;
523			goto bad;
524		}
525
526		/* Initialize IPv6 header */
527		ip6o = mtod(m, struct ip6_hdr *);
528		ip6o->ip6_flow = 0;
529		ip6o->ip6_vfc &= ~IPV6_VERSION_MASK;
530		ip6o->ip6_vfc |= IPV6_VERSION;
531		ip6o->ip6_plen = htons(m->m_pkthdr.len);
532		ip6o->ip6_hlim = ip_defttl;
533		ip6o->ip6_dst = saidx->dst.sin6.sin6_addr;
534		ip6o->ip6_src = saidx->src.sin6.sin6_addr;
535
536#ifdef INET
537		if (tp == IPVERSION) {
538			/* Save ECN notification */
539			m_copydata(m, sizeof(struct ip6_hdr) +
540			    offsetof(struct ip, ip_tos), sizeof(u_int8_t),
541			    (caddr_t) &itos);
542
543			/* This is really IPVERSION. */
544			ip6o->ip6_nxt = IPPROTO_IPIP;
545		} else
546#endif /* INET */
547			if (tp == (IPV6_VERSION >> 4)) {
548				u_int32_t itos32;
549
550				/* Save ECN notification. */
551				m_copydata(m, sizeof(struct ip6_hdr) +
552				    offsetof(struct ip6_hdr, ip6_flow),
553				    sizeof(u_int32_t), (caddr_t) &itos32);
554				itos = ntohl(itos32) >> 20;
555
556				ip6o->ip6_nxt = IPPROTO_IPV6;
557			} else {
558				goto nofamily;
559			}
560
561		otos = 0;
562		ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
563		ip6o->ip6_flow |= htonl((u_int32_t) otos << 20);
564		break;
565#endif /* INET6 */
566
567	default:
568nofamily:
569		DPRINTF(("%s: unsupported protocol family %u\n", __func__,
570		    saidx->dst.sa.sa_family));
571		ipipstat.ipips_family++;
572		error = EAFNOSUPPORT;		/* XXX diffs from openbsd */
573		goto bad;
574	}
575
576	ipipstat.ipips_opackets++;
577	*mp = m;
578
579#ifdef INET
580	if (saidx->dst.sa.sa_family == AF_INET) {
581#if 0
582		if (sav->tdb_xform->xf_type == XF_IP4)
583			tdb->tdb_cur_bytes +=
584			    m->m_pkthdr.len - sizeof(struct ip);
585#endif
586		ipipstat.ipips_obytes += m->m_pkthdr.len - sizeof(struct ip);
587	}
588#endif /* INET */
589
590#ifdef INET6
591	if (saidx->dst.sa.sa_family == AF_INET6) {
592#if 0
593		if (sav->tdb_xform->xf_type == XF_IP4)
594			tdb->tdb_cur_bytes +=
595			    m->m_pkthdr.len - sizeof(struct ip6_hdr);
596#endif
597		ipipstat.ipips_obytes +=
598		    m->m_pkthdr.len - sizeof(struct ip6_hdr);
599	}
600#endif /* INET6 */
601
602	return 0;
603bad:
604	if (m)
605		m_freem(m);
606	*mp = NULL;
607	return (error);
608}
609
610#ifdef FAST_IPSEC
611static int
612ipe4_init(struct secasvar *sav, struct xformsw *xsp)
613{
614	sav->tdb_xform = xsp;
615	return 0;
616}
617
618static int
619ipe4_zeroize(struct secasvar *sav)
620{
621	sav->tdb_xform = NULL;
622	return 0;
623}
624
625static int
626ipe4_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
627{
628	/* This is a rather serious mistake, so no conditional printing. */
629	printf("%s: should never be called\n", __func__);
630	if (m)
631		m_freem(m);
632	return EOPNOTSUPP;
633}
634
635static struct xformsw ipe4_xformsw = {
636	XF_IP4,		0,		"IPv4 Simple Encapsulation",
637	ipe4_init,	ipe4_zeroize,	ipe4_input,	ipip_output,
638};
639
640extern struct domain inetdomain;
641static struct ipprotosw ipe4_protosw[] = {
642{ SOCK_RAW,	&inetdomain,	IPPROTO_IPV4,	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
643  (pr_in_input_t*) ip4_input,
644		0, 		0,		rip_ctloutput,
645  0,
646  0,		0,		0,		0,
647  &rip_usrreqs
648},
649#ifdef INET6
650{ SOCK_RAW,	&inetdomain,	IPPROTO_IPV6,	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
651  (pr_in_input_t*) ip4_input,
652		0,	 	0,		rip_ctloutput,
653  0,
654  0,		0,		0,		0,
655  &rip_usrreqs
656}
657#endif
658};
659
660/*
661 * Check the encapsulated packet to see if we want it
662 */
663static int
664ipe4_encapcheck(const struct mbuf *m, int off, int proto, void *arg)
665{
666	/*
667	 * Only take packets coming from IPSEC tunnels; the rest
668	 * must be handled by the gif tunnel code.  Note that we
669	 * also return a minimum priority when we want the packet
670	 * so any explicit gif tunnels take precedence.
671	 */
672	return ((m->m_flags & M_IPSEC) != 0 ? 1 : 0);
673}
674
675static void
676ipe4_attach(void)
677{
678	xform_register(&ipe4_xformsw);
679	/* attach to encapsulation framework */
680	/* XXX save return cookie for detach on module remove */
681	(void) encap_attach_func(AF_INET, -1,
682		ipe4_encapcheck, (struct protosw*) &ipe4_protosw[0], NULL);
683#ifdef INET6
684	(void) encap_attach_func(AF_INET6, -1,
685		ipe4_encapcheck, (struct protosw*) &ipe4_protosw[1], NULL);
686#endif
687}
688SYSINIT(ipe4_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, ipe4_attach, NULL);
689#endif	/* FAST_IPSEC */
690