1/*	$NetBSD: ip_gre.c,v 1.29 2003/09/05 23:02:43 itojun Exp $ */
2
3/*-
4 * Copyright (c) 1998 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Heiko W.Rupp <hwr@pilhuhn.de>
9 *
10 * IPv6-over-GRE contributed by Gert Doering <gert@greenie.muc.de>
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 *    notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
23 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31 * POSSIBILITY OF SUCH DAMAGE.
32 */
33
34/*
35 * deencapsulate tunneled packets and send them on
36 * output half is in net/if_gre.[ch]
37 * This currently handles IPPROTO_GRE, IPPROTO_MOBILE
38 */
39
40#include <sys/cdefs.h>
41__FBSDID("$FreeBSD$");
42
43#include "opt_inet.h"
44#include "opt_atalk.h"
45#include "opt_inet6.h"
46
47#include <sys/param.h>
48#include <sys/systm.h>
49#include <sys/mbuf.h>
50#include <sys/socket.h>
51#include <sys/socketvar.h>
52#include <sys/protosw.h>
53#include <sys/errno.h>
54#include <sys/time.h>
55#include <sys/kernel.h>
56#include <sys/syslog.h>
57#include <net/bpf.h>
58#include <net/ethernet.h>
59#include <net/if.h>
60#include <net/netisr.h>
61#include <net/route.h>
62#include <net/raw_cb.h>
63
64#ifdef INET
65#include <netinet/in.h>
66#include <netinet/in_var.h>
67#include <netinet/in_systm.h>
68#include <netinet/ip.h>
69#include <netinet/ip_var.h>
70#include <netinet/ip_gre.h>
71#include <machine/in_cksum.h>
72#else
73#error ip_gre input without IP?
74#endif
75
76#ifdef NETATALK
77#include <netatalk/at.h>
78#include <netatalk/at_var.h>
79#include <netatalk/at_extern.h>
80#endif
81
82/* Needs IP headers. */
83#include <net/if_gre.h>
84
85#include <machine/stdarg.h>
86
87#if 1
88void gre_inet_ntoa(struct in_addr in);	/* XXX */
89#endif
90
91static struct gre_softc *gre_lookup(struct mbuf *, u_int8_t);
92
93static struct mbuf *gre_input2(struct mbuf *, int, u_char);
94
95/*
96 * De-encapsulate a packet and feed it back through ip input (this
97 * routine is called whenever IP gets a packet with proto type
98 * IPPROTO_GRE and a local destination address).
99 * This really is simple
100 */
101void
102gre_input(struct mbuf *m, int off)
103{
104	int proto;
105
106	proto = (mtod(m, struct ip *))->ip_p;
107
108	m = gre_input2(m, off, proto);
109
110	/*
111	 * If no matching tunnel that is up is found. We inject
112	 * the mbuf to raw ip socket to see if anyone picks it up.
113	 */
114	if (m != NULL)
115		rip_input(m, off);
116}
117
118/*
119 * Decapsulate. Does the real work and is called from gre_input()
120 * (above). Returns an mbuf back if packet is not yet processed,
121 * and NULL if it needs no further processing. proto is the protocol
122 * number of the "calling" foo_input() routine.
123 */
124static struct mbuf *
125gre_input2(struct mbuf *m ,int hlen, u_char proto)
126{
127	struct greip *gip;
128	int isr;
129	struct gre_softc *sc;
130	u_int16_t flags;
131	u_int32_t af;
132
133	if ((sc = gre_lookup(m, proto)) == NULL) {
134		/* No matching tunnel or tunnel is down. */
135		return (m);
136	}
137
138	if (m->m_len < sizeof(*gip)) {
139		m = m_pullup(m, sizeof(*gip));
140		if (m == NULL)
141			return (NULL);
142	}
143	gip = mtod(m, struct greip *);
144
145	GRE2IFP(sc)->if_ipackets++;
146	GRE2IFP(sc)->if_ibytes += m->m_pkthdr.len;
147
148	switch (proto) {
149	case IPPROTO_GRE:
150		hlen += sizeof(struct gre_h);
151
152		/* process GRE flags as packet can be of variable len */
153		flags = ntohs(gip->gi_flags);
154
155		/* Checksum & Offset are present */
156		if ((flags & GRE_CP) | (flags & GRE_RP))
157			hlen += 4;
158		/* We don't support routing fields (variable length) */
159		if (flags & GRE_RP)
160			return (m);
161		if (flags & GRE_KP)
162			hlen += 4;
163		if (flags & GRE_SP)
164			hlen += 4;
165
166		switch (ntohs(gip->gi_ptype)) { /* ethertypes */
167		case WCCP_PROTOCOL_TYPE:
168			if (sc->wccp_ver == WCCP_V2)
169				hlen += 4;
170			/* FALLTHROUGH */
171		case ETHERTYPE_IP:	/* shouldn't need a schednetisr(), */
172			isr = NETISR_IP;/* as we are in ip_input */
173			af = AF_INET;
174			break;
175#ifdef INET6
176		case ETHERTYPE_IPV6:
177			isr = NETISR_IPV6;
178			af = AF_INET6;
179			break;
180#endif
181#ifdef NETATALK
182		case ETHERTYPE_ATALK:
183			isr = NETISR_ATALK1;
184			af = AF_APPLETALK;
185			break;
186#endif
187		default:
188			/* Others not yet supported. */
189			return (m);
190		}
191		break;
192	default:
193		/* Others not yet supported. */
194		return (m);
195	}
196
197	if (hlen > m->m_pkthdr.len) {
198		m_freem(m);
199		return (NULL);
200	}
201	/* Unlike NetBSD, in FreeBSD m_adj() adjusts m->m_pkthdr.len as well */
202	m_adj(m, hlen);
203
204	if (bpf_peers_present(GRE2IFP(sc)->if_bpf)) {
205		bpf_mtap2(GRE2IFP(sc)->if_bpf, &af, sizeof(af), m);
206	}
207
208	if ((GRE2IFP(sc)->if_flags & IFF_MONITOR) != 0) {
209		m_freem(m);
210		return(NULL);
211	}
212
213	m->m_pkthdr.rcvif = GRE2IFP(sc);
214
215	netisr_queue(isr, m);
216
217	/* Packet is done, no further processing needed. */
218	return (NULL);
219}
220
221/*
222 * input routine for IPPRPOTO_MOBILE
223 * This is a little bit diffrent from the other modes, as the
224 * encapsulating header was not prepended, but instead inserted
225 * between IP header and payload
226 */
227
228void
229gre_mobile_input(struct mbuf *m, int hlen)
230{
231	struct ip *ip;
232	struct mobip_h *mip;
233	struct gre_softc *sc;
234	int msiz;
235
236	if ((sc = gre_lookup(m, IPPROTO_MOBILE)) == NULL) {
237		/* No matching tunnel or tunnel is down. */
238		m_freem(m);
239		return;
240	}
241
242	if (m->m_len < sizeof(*mip)) {
243		m = m_pullup(m, sizeof(*mip));
244		if (m == NULL)
245			return;
246	}
247	ip = mtod(m, struct ip *);
248	mip = mtod(m, struct mobip_h *);
249
250	GRE2IFP(sc)->if_ipackets++;
251	GRE2IFP(sc)->if_ibytes += m->m_pkthdr.len;
252
253	if (ntohs(mip->mh.proto) & MOB_H_SBIT) {
254		msiz = MOB_H_SIZ_L;
255		mip->mi.ip_src.s_addr = mip->mh.osrc;
256	} else
257		msiz = MOB_H_SIZ_S;
258
259	if (m->m_len < (ip->ip_hl << 2) + msiz) {
260		m = m_pullup(m, (ip->ip_hl << 2) + msiz);
261		if (m == NULL)
262			return;
263		ip = mtod(m, struct ip *);
264		mip = mtod(m, struct mobip_h *);
265	}
266
267	mip->mi.ip_dst.s_addr = mip->mh.odst;
268	mip->mi.ip_p = (ntohs(mip->mh.proto) >> 8);
269
270	if (gre_in_cksum((u_int16_t *)&mip->mh, msiz) != 0) {
271		m_freem(m);
272		return;
273	}
274
275	bcopy((caddr_t)(ip) + (ip->ip_hl << 2) + msiz, (caddr_t)(ip) +
276	    (ip->ip_hl << 2), m->m_len - msiz - (ip->ip_hl << 2));
277	m->m_len -= msiz;
278	m->m_pkthdr.len -= msiz;
279
280	/*
281	 * On FreeBSD, rip_input() supplies us with ip->ip_len
282	 * already converted into host byteorder and also decreases
283	 * it by the lengh of IP header, however, ip_input() expects
284	 * that this field is in the original format (network byteorder
285	 * and full size of IP packet), so that adjust accordingly.
286	 */
287	ip->ip_len = htons(ip->ip_len + sizeof(struct ip) - msiz);
288
289	ip->ip_sum = 0;
290	ip->ip_sum = in_cksum(m, (ip->ip_hl << 2));
291
292	if (bpf_peers_present(GRE2IFP(sc)->if_bpf)) {
293		u_int32_t af = AF_INET;
294		bpf_mtap2(GRE2IFP(sc)->if_bpf, &af, sizeof(af), m);
295	}
296
297	if ((GRE2IFP(sc)->if_flags & IFF_MONITOR) != 0) {
298		m_freem(m);
299		return;
300	}
301
302	m->m_pkthdr.rcvif = GRE2IFP(sc);
303
304	netisr_queue(NETISR_IP, m);
305}
306
307/*
308 * Find the gre interface associated with our src/dst/proto set.
309 *
310 * XXXRW: Need some sort of drain/refcount mechanism so that the softc
311 * reference remains valid after it's returned from gre_lookup().  Right
312 * now, I'm thinking it should be reference-counted with a gre_dropref()
313 * when the caller is done with the softc.  This is complicated by how
314 * to handle destroying the gre softc; probably using a gre_drain() in
315 * in_gre.c during destroy.
316 */
317static struct gre_softc *
318gre_lookup(struct mbuf *m, u_int8_t proto)
319{
320	struct ip *ip = mtod(m, struct ip *);
321	struct gre_softc *sc;
322
323	mtx_lock(&gre_mtx);
324	for (sc = LIST_FIRST(&gre_softc_list); sc != NULL;
325	     sc = LIST_NEXT(sc, sc_list)) {
326		if ((sc->g_dst.s_addr == ip->ip_src.s_addr) &&
327		    (sc->g_src.s_addr == ip->ip_dst.s_addr) &&
328		    (sc->g_proto == proto) &&
329		    ((GRE2IFP(sc)->if_flags & IFF_UP) != 0)) {
330			mtx_unlock(&gre_mtx);
331			return (sc);
332		}
333	}
334	mtx_unlock(&gre_mtx);
335
336	return (NULL);
337}
338