xref: /freebsd/sys/netinet6/in6_gif.c (revision 2e3f49888ec8851bafb22011533217487764fdb0) 
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
5  * Copyright (c) 2018 Andrey V. Elsukov <ae@FreeBSD.org>
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the project nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  *	$KAME: in6_gif.c,v 1.49 2001/05/14 14:02:17 itojun Exp $
33  */
34 
35 #include <sys/cdefs.h>
36 #include "opt_inet.h"
37 #include "opt_inet6.h"
38 
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/jail.h>
42 #include <sys/socket.h>
43 #include <sys/sockio.h>
44 #include <sys/mbuf.h>
45 #include <sys/errno.h>
46 #include <sys/kernel.h>
47 #include <sys/syslog.h>
48 #include <sys/sysctl.h>
49 #include <sys/malloc.h>
50 #include <sys/proc.h>
51 
52 #include <net/ethernet.h>
53 #include <net/if.h>
54 #include <net/if_var.h>
55 #include <net/if_private.h>
56 #include <net/route.h>
57 #include <net/vnet.h>
58 
59 #include <netinet/in.h>
60 #include <netinet/in_systm.h>
61 #ifdef INET
62 #include <netinet/ip.h>
63 #include <netinet/ip_ecn.h>
64 #endif
65 #include <netinet/ip_encap.h>
66 #include <netinet/ip6.h>
67 #include <netinet6/ip6_var.h>
68 #include <netinet6/in6_var.h>
69 #include <netinet6/scope6_var.h>
70 #include <netinet6/ip6_ecn.h>
71 #include <netinet6/in6_fib.h>
72 
73 #include <net/if_gif.h>
74 
75 #define GIF_HLIM	30
76 VNET_DEFINE_STATIC(int, ip6_gif_hlim) = GIF_HLIM;
77 #define	V_ip6_gif_hlim			VNET(ip6_gif_hlim)
78 
79 SYSCTL_DECL(_net_inet6_ip6);
80 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_GIF_HLIM, gifhlim,
81     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_gif_hlim), 0,
82     "Default hop limit for encapsulated packets");
83 
84 /*
85  * We keep interfaces in a hash table using src+dst as key.
86  * Interfaces with GIF_IGNORE_SOURCE flag are linked into plain list.
87  */
88 VNET_DEFINE_STATIC(struct gif_list *, ipv6_hashtbl) = NULL;
89 VNET_DEFINE_STATIC(struct gif_list *, ipv6_srchashtbl) = NULL;
90 VNET_DEFINE_STATIC(struct gif_list, ipv6_list) = CK_LIST_HEAD_INITIALIZER();
91 #define	V_ipv6_hashtbl		VNET(ipv6_hashtbl)
92 #define	V_ipv6_srchashtbl	VNET(ipv6_srchashtbl)
93 #define	V_ipv6_list		VNET(ipv6_list)
94 
95 #define	GIF_HASH(src, dst)	(V_ipv6_hashtbl[\
96     in6_gif_hashval((src), (dst)) & (GIF_HASH_SIZE - 1)])
97 #define	GIF_SRCHASH(src)	(V_ipv6_srchashtbl[\
98     fnv_32_buf((src), sizeof(*src), FNV1_32_INIT) & (GIF_HASH_SIZE - 1)])
99 #define	GIF_HASH_SC(sc)		GIF_HASH(&(sc)->gif_ip6hdr->ip6_src,\
100     &(sc)->gif_ip6hdr->ip6_dst)
101 static uint32_t
102 in6_gif_hashval(const struct in6_addr *src, const struct in6_addr *dst)
103 {
104 	uint32_t ret;
105 
106 	ret = fnv_32_buf(src, sizeof(*src), FNV1_32_INIT);
107 	return (fnv_32_buf(dst, sizeof(*dst), ret));
108 }
109 
110 static int
111 in6_gif_checkdup(const struct gif_softc *sc, const struct in6_addr *src,
112     const struct in6_addr *dst)
113 {
114 	struct gif_softc *tmp;
115 
116 	if (sc->gif_family == AF_INET6 &&
117 	    IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_src, src) &&
118 	    IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_dst, dst))
119 		return (EEXIST);
120 
121 	CK_LIST_FOREACH(tmp, &GIF_HASH(src, dst), chain) {
122 		if (tmp == sc)
123 			continue;
124 		if (IN6_ARE_ADDR_EQUAL(&tmp->gif_ip6hdr->ip6_src, src) &&
125 		    IN6_ARE_ADDR_EQUAL(&tmp->gif_ip6hdr->ip6_dst, dst))
126 			return (EADDRNOTAVAIL);
127 	}
128 	return (0);
129 }
130 
131 /*
132  * Check that ingress address belongs to local host.
133  */
134 static void
135 in6_gif_set_running(struct gif_softc *sc)
136 {
137 
138 	if (in6_localip(&sc->gif_ip6hdr->ip6_src))
139 		GIF2IFP(sc)->if_drv_flags |= IFF_DRV_RUNNING;
140 	else
141 		GIF2IFP(sc)->if_drv_flags &= ~IFF_DRV_RUNNING;
142 }
143 
144 /*
145  * ifaddr_event handler.
146  * Clear IFF_DRV_RUNNING flag when ingress address disappears to prevent
147  * source address spoofing.
148  */
149 static void
150 in6_gif_srcaddr(void *arg __unused, const struct sockaddr *sa, int event)
151 {
152 	const struct sockaddr_in6 *sin;
153 	struct gif_softc *sc;
154 
155 	/* Check that VNET is ready */
156 	if (V_ipv6_hashtbl == NULL)
157 		return;
158 
159 	NET_EPOCH_ASSERT();
160 	sin = (const struct sockaddr_in6 *)sa;
161 	CK_LIST_FOREACH(sc, &GIF_SRCHASH(&sin->sin6_addr), srchash) {
162 		if (IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_src,
163 		    &sin->sin6_addr) == 0)
164 			continue;
165 		in6_gif_set_running(sc);
166 	}
167 }
168 
169 static void
170 in6_gif_attach(struct gif_softc *sc)
171 {
172 
173 	if (sc->gif_options & GIF_IGNORE_SOURCE)
174 		CK_LIST_INSERT_HEAD(&V_ipv6_list, sc, chain);
175 	else
176 		CK_LIST_INSERT_HEAD(&GIF_HASH_SC(sc), sc, chain);
177 
178 	CK_LIST_INSERT_HEAD(&GIF_SRCHASH(&sc->gif_ip6hdr->ip6_src),
179 	    sc, srchash);
180 }
181 
182 int
183 in6_gif_setopts(struct gif_softc *sc, u_int options)
184 {
185 
186 	/* NOTE: we are protected with gif_ioctl_sx lock */
187 	MPASS(sc->gif_family == AF_INET6);
188 	MPASS(sc->gif_options != options);
189 
190 	if ((options & GIF_IGNORE_SOURCE) !=
191 	    (sc->gif_options & GIF_IGNORE_SOURCE)) {
192 		CK_LIST_REMOVE(sc, srchash);
193 		CK_LIST_REMOVE(sc, chain);
194 		sc->gif_options = options;
195 		in6_gif_attach(sc);
196 	}
197 	return (0);
198 }
199 
200 int
201 in6_gif_ioctl(struct gif_softc *sc, u_long cmd, caddr_t data)
202 {
203 	struct in6_ifreq *ifr = (struct in6_ifreq *)data;
204 	struct sockaddr_in6 *dst, *src;
205 	struct ip6_hdr *ip6;
206 	int error;
207 
208 	/* NOTE: we are protected with gif_ioctl_sx lock */
209 	error = EINVAL;
210 	switch (cmd) {
211 	case SIOCSIFPHYADDR_IN6:
212 		src = &((struct in6_aliasreq *)data)->ifra_addr;
213 		dst = &((struct in6_aliasreq *)data)->ifra_dstaddr;
214 
215 		/* sanity checks */
216 		if (src->sin6_family != dst->sin6_family ||
217 		    src->sin6_family != AF_INET6 ||
218 		    src->sin6_len != dst->sin6_len ||
219 		    src->sin6_len != sizeof(*src))
220 			break;
221 		if (IN6_IS_ADDR_UNSPECIFIED(&src->sin6_addr) ||
222 		    IN6_IS_ADDR_UNSPECIFIED(&dst->sin6_addr)) {
223 			error = EADDRNOTAVAIL;
224 			break;
225 		}
226 		/*
227 		 * Check validity of the scope zone ID of the
228 		 * addresses, and convert it into the kernel
229 		 * internal form if necessary.
230 		 */
231 		if ((error = sa6_embedscope(src, 0)) != 0 ||
232 		    (error = sa6_embedscope(dst, 0)) != 0)
233 			break;
234 
235 		if (V_ipv6_hashtbl == NULL) {
236 			V_ipv6_hashtbl = gif_hashinit();
237 			V_ipv6_srchashtbl = gif_hashinit();
238 		}
239 		error = in6_gif_checkdup(sc, &src->sin6_addr,
240 		    &dst->sin6_addr);
241 		if (error == EADDRNOTAVAIL)
242 			break;
243 		if (error == EEXIST) {
244 			/* Addresses are the same. Just return. */
245 			error = 0;
246 			break;
247 		}
248 		ip6 = malloc(sizeof(*ip6), M_GIF, M_WAITOK | M_ZERO);
249 		ip6->ip6_src = src->sin6_addr;
250 		ip6->ip6_dst = dst->sin6_addr;
251 		ip6->ip6_vfc = IPV6_VERSION;
252 		if (sc->gif_family != 0) {
253 			/* Detach existing tunnel first */
254 			CK_LIST_REMOVE(sc, srchash);
255 			CK_LIST_REMOVE(sc, chain);
256 			GIF_WAIT();
257 			free(sc->gif_hdr, M_GIF);
258 			/* XXX: should we notify about link state change? */
259 		}
260 		sc->gif_family = AF_INET6;
261 		sc->gif_ip6hdr = ip6;
262 		in6_gif_attach(sc);
263 		in6_gif_set_running(sc);
264 		break;
265 	case SIOCGIFPSRCADDR_IN6:
266 	case SIOCGIFPDSTADDR_IN6:
267 		if (sc->gif_family != AF_INET6) {
268 			error = EADDRNOTAVAIL;
269 			break;
270 		}
271 		src = (struct sockaddr_in6 *)&ifr->ifr_addr;
272 		memset(src, 0, sizeof(*src));
273 		src->sin6_family = AF_INET6;
274 		src->sin6_len = sizeof(*src);
275 		src->sin6_addr = (cmd == SIOCGIFPSRCADDR_IN6) ?
276 		    sc->gif_ip6hdr->ip6_src: sc->gif_ip6hdr->ip6_dst;
277 		error = prison_if(curthread->td_ucred, (struct sockaddr *)src);
278 		if (error == 0)
279 			error = sa6_recoverscope(src);
280 		if (error != 0)
281 			memset(src, 0, sizeof(*src));
282 		break;
283 	}
284 	return (error);
285 }
286 
287 int
288 in6_gif_output(struct ifnet *ifp, struct mbuf *m, int proto, uint8_t ecn)
289 {
290 	struct gif_softc *sc = ifp->if_softc;
291 	struct ip6_hdr *ip6;
292 
293 	/* prepend new IP header */
294 	NET_EPOCH_ASSERT();
295 	M_PREPEND(m, sizeof(struct ip6_hdr), M_NOWAIT);
296 	if (m == NULL)
297 		return (ENOBUFS);
298 
299 	ip6 = mtod(m, struct ip6_hdr *);
300 	MPASS(sc->gif_family == AF_INET6);
301 	memcpy(ip6, sc->gif_ip6hdr, sizeof(struct ip6_hdr));
302 
303 	ip6->ip6_flow  |= htonl((uint32_t)ecn << 20);
304 	ip6->ip6_nxt	= proto;
305 	ip6->ip6_hlim	= V_ip6_gif_hlim;
306 	/*
307 	 * force fragmentation to minimum MTU, to avoid path MTU discovery.
308 	 * it is too painful to ask for resend of inner packet, to achieve
309 	 * path MTU discovery for encapsulated packets.
310 	 */
311 	return (ip6_output(m, 0, NULL, IPV6_MINMTU, 0, NULL, NULL));
312 }
313 
314 static int
315 in6_gif_input(struct mbuf *m, int off, int proto, void *arg)
316 {
317 	struct gif_softc *sc = arg;
318 	struct ifnet *gifp;
319 	struct ip6_hdr *ip6;
320 	uint8_t ecn;
321 
322 	NET_EPOCH_ASSERT();
323 	if (sc == NULL) {
324 		m_freem(m);
325 		IP6STAT_INC(ip6s_nogif);
326 		return (IPPROTO_DONE);
327 	}
328 	gifp = GIF2IFP(sc);
329 	if ((gifp->if_flags & IFF_UP) != 0) {
330 		ip6 = mtod(m, struct ip6_hdr *);
331 		ecn = IPV6_TRAFFIC_CLASS(ip6);
332 		m_adj(m, off);
333 		gif_input(m, gifp, proto, ecn);
334 	} else {
335 		m_freem(m);
336 		IP6STAT_INC(ip6s_nogif);
337 	}
338 	return (IPPROTO_DONE);
339 }
340 
341 static int
342 in6_gif_lookup(const struct mbuf *m, int off, int proto, void **arg)
343 {
344 	const struct ip6_hdr *ip6;
345 	struct gif_softc *sc;
346 	int ret;
347 
348 	if (V_ipv6_hashtbl == NULL)
349 		return (0);
350 
351 	NET_EPOCH_ASSERT();
352 	/*
353 	 * NOTE: it is safe to iterate without any locking here, because softc
354 	 * can be reclaimed only when we are not within net_epoch_preempt
355 	 * section, but ip_encap lookup+input are executed in epoch section.
356 	 */
357 	ip6 = mtod(m, const struct ip6_hdr *);
358 	ret = 0;
359 	CK_LIST_FOREACH(sc, &GIF_HASH(&ip6->ip6_dst, &ip6->ip6_src), chain) {
360 		/*
361 		 * This is an inbound packet, its ip6_dst is source address
362 		 * in softc.
363 		 */
364 		if (IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_src,
365 		    &ip6->ip6_dst) &&
366 		    IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_dst,
367 		    &ip6->ip6_src)) {
368 			ret = ENCAP_DRV_LOOKUP;
369 			goto done;
370 		}
371 	}
372 	/*
373 	 * No exact match.
374 	 * Check the list of interfaces with GIF_IGNORE_SOURCE flag.
375 	 */
376 	CK_LIST_FOREACH(sc, &V_ipv6_list, chain) {
377 		if (IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_src,
378 		    &ip6->ip6_dst)) {
379 			ret = 128 + 8; /* src + proto */
380 			goto done;
381 		}
382 	}
383 	return (0);
384 done:
385 	if ((GIF2IFP(sc)->if_flags & IFF_UP) == 0)
386 		return (0);
387 	/* ingress filters on outer source */
388 	if ((GIF2IFP(sc)->if_flags & IFF_LINK2) == 0) {
389 		if (fib6_check_urpf(sc->gif_fibnum, &ip6->ip6_src,
390 		    ntohs(in6_getscope(&ip6->ip6_src)), NHR_NONE,
391 		    m->m_pkthdr.rcvif) == 0)
392 			return (0);
393 	}
394 	*arg = sc;
395 	return (ret);
396 }
397 
398 static const struct srcaddrtab *ipv6_srcaddrtab;
399 static struct {
400 	const struct encap_config encap;
401 	const struct encaptab *cookie;
402 } ipv6_encap_cfg[] = {
403 #ifdef INET
404 	{
405 		.encap = {
406 			.proto = IPPROTO_IPV4,
407 			.min_length = sizeof(struct ip6_hdr) +
408 			    sizeof(struct ip),
409 			.exact_match = ENCAP_DRV_LOOKUP,
410 			.lookup = in6_gif_lookup,
411 			.input = in6_gif_input
412 		},
413 	},
414 #endif
415 	{
416 		.encap = {
417 			.proto = IPPROTO_IPV6,
418 			.min_length = 2 * sizeof(struct ip6_hdr),
419 			.exact_match = ENCAP_DRV_LOOKUP,
420 			.lookup = in6_gif_lookup,
421 			.input = in6_gif_input
422 		},
423 	},
424 	{
425 		.encap = {
426 			.proto = IPPROTO_ETHERIP,
427 			.min_length = sizeof(struct ip6_hdr) +
428 			    sizeof(struct etherip_header) +
429 			    sizeof(struct ether_header),
430 			.exact_match = ENCAP_DRV_LOOKUP,
431 			.lookup = in6_gif_lookup,
432 			.input = in6_gif_input
433 		},
434 	}
435 };
436 
437 void
438 in6_gif_init(void)
439 {
440 	int i;
441 
442 	if (!IS_DEFAULT_VNET(curvnet))
443 		return;
444 
445 	ipv6_srcaddrtab = ip6_encap_register_srcaddr(in6_gif_srcaddr,
446 	    NULL, M_WAITOK);
447 	for (i = 0; i < nitems(ipv6_encap_cfg); i++)
448 		ipv6_encap_cfg[i].cookie = ip6_encap_attach(
449 		    &ipv6_encap_cfg[i].encap, NULL, M_WAITOK);
450 }
451 
452 void
453 in6_gif_uninit(void)
454 {
455 	int i;
456 
457 	if (IS_DEFAULT_VNET(curvnet)) {
458 		for (i = 0; i < nitems(ipv6_encap_cfg); i++)
459 			ip6_encap_detach(ipv6_encap_cfg[i].cookie);
460 		ip6_encap_unregister_srcaddr(ipv6_srcaddrtab);
461 	}
462 	if (V_ipv6_hashtbl != NULL) {
463 		gif_hashdestroy(V_ipv6_hashtbl);
464 		V_ipv6_hashtbl = NULL;
465 		GIF_WAIT();
466 		gif_hashdestroy(V_ipv6_srchashtbl);
467 	}
468 }
469