xref: /freebsd/sys/netinet6/in6_gif.c (revision 9e5787d2284e187abb5b654d924394a65772e004) 
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 __FBSDID("$FreeBSD$");
37 
38 #include "opt_inet.h"
39 #include "opt_inet6.h"
40 
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/jail.h>
44 #include <sys/socket.h>
45 #include <sys/sockio.h>
46 #include <sys/mbuf.h>
47 #include <sys/errno.h>
48 #include <sys/kernel.h>
49 #include <sys/syslog.h>
50 #include <sys/sysctl.h>
51 #include <sys/malloc.h>
52 #include <sys/proc.h>
53 
54 #include <net/ethernet.h>
55 #include <net/if.h>
56 #include <net/if_var.h>
57 #include <net/route.h>
58 #include <net/vnet.h>
59 
60 #include <netinet/in.h>
61 #include <netinet/in_systm.h>
62 #ifdef INET
63 #include <netinet/ip.h>
64 #include <netinet/ip_ecn.h>
65 #endif
66 #include <netinet/ip_encap.h>
67 #include <netinet/ip6.h>
68 #include <netinet6/ip6_var.h>
69 #include <netinet6/in6_var.h>
70 #include <netinet6/scope6_var.h>
71 #include <netinet6/ip6_ecn.h>
72 #include <netinet6/in6_fib.h>
73 
74 #include <net/if_gif.h>
75 
76 #define GIF_HLIM	30
77 VNET_DEFINE_STATIC(int, ip6_gif_hlim) = GIF_HLIM;
78 #define	V_ip6_gif_hlim			VNET(ip6_gif_hlim)
79 
80 SYSCTL_DECL(_net_inet6_ip6);
81 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_GIF_HLIM, gifhlim,
82     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_gif_hlim), 0,
83     "Default hop limit for encapsulated packets");
84 
85 /*
86  * We keep interfaces in a hash table using src+dst as key.
87  * Interfaces with GIF_IGNORE_SOURCE flag are linked into plain list.
88  */
89 VNET_DEFINE_STATIC(struct gif_list *, ipv6_hashtbl) = NULL;
90 VNET_DEFINE_STATIC(struct gif_list *, ipv6_srchashtbl) = NULL;
91 VNET_DEFINE_STATIC(struct gif_list, ipv6_list) = CK_LIST_HEAD_INITIALIZER();
92 #define	V_ipv6_hashtbl		VNET(ipv6_hashtbl)
93 #define	V_ipv6_srchashtbl	VNET(ipv6_srchashtbl)
94 #define	V_ipv6_list		VNET(ipv6_list)
95 
96 #define	GIF_HASH(src, dst)	(V_ipv6_hashtbl[\
97     in6_gif_hashval((src), (dst)) & (GIF_HASH_SIZE - 1)])
98 #define	GIF_SRCHASH(src)	(V_ipv6_srchashtbl[\
99     fnv_32_buf((src), sizeof(*src), FNV1_32_INIT) & (GIF_HASH_SIZE - 1)])
100 #define	GIF_HASH_SC(sc)		GIF_HASH(&(sc)->gif_ip6hdr->ip6_src,\
101     &(sc)->gif_ip6hdr->ip6_dst)
102 static uint32_t
103 in6_gif_hashval(const struct in6_addr *src, const struct in6_addr *dst)
104 {
105 	uint32_t ret;
106 
107 	ret = fnv_32_buf(src, sizeof(*src), FNV1_32_INIT);
108 	return (fnv_32_buf(dst, sizeof(*dst), ret));
109 }
110 
111 static int
112 in6_gif_checkdup(const struct gif_softc *sc, const struct in6_addr *src,
113     const struct in6_addr *dst)
114 {
115 	struct gif_softc *tmp;
116 
117 	if (sc->gif_family == AF_INET6 &&
118 	    IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_src, src) &&
119 	    IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_dst, dst))
120 		return (EEXIST);
121 
122 	CK_LIST_FOREACH(tmp, &GIF_HASH(src, dst), chain) {
123 		if (tmp == sc)
124 			continue;
125 		if (IN6_ARE_ADDR_EQUAL(&tmp->gif_ip6hdr->ip6_src, src) &&
126 		    IN6_ARE_ADDR_EQUAL(&tmp->gif_ip6hdr->ip6_dst, dst))
127 			return (EADDRNOTAVAIL);
128 	}
129 	return (0);
130 }
131 
132 /*
133  * Check that ingress address belongs to local host.
134  */
135 static void
136 in6_gif_set_running(struct gif_softc *sc)
137 {
138 
139 	if (in6_localip(&sc->gif_ip6hdr->ip6_src))
140 		GIF2IFP(sc)->if_drv_flags |= IFF_DRV_RUNNING;
141 	else
142 		GIF2IFP(sc)->if_drv_flags &= ~IFF_DRV_RUNNING;
143 }
144 
145 /*
146  * ifaddr_event handler.
147  * Clear IFF_DRV_RUNNING flag when ingress address disappears to prevent
148  * source address spoofing.
149  */
150 static void
151 in6_gif_srcaddr(void *arg __unused, const struct sockaddr *sa, int event)
152 {
153 	const struct sockaddr_in6 *sin;
154 	struct gif_softc *sc;
155 
156 	/* Check that VNET is ready */
157 	if (V_ipv6_hashtbl == NULL)
158 		return;
159 
160 	NET_EPOCH_ASSERT();
161 	sin = (const struct sockaddr_in6 *)sa;
162 	CK_LIST_FOREACH(sc, &GIF_SRCHASH(&sin->sin6_addr), srchash) {
163 		if (IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_src,
164 		    &sin->sin6_addr) == 0)
165 			continue;
166 		in6_gif_set_running(sc);
167 	}
168 }
169 
170 static void
171 in6_gif_attach(struct gif_softc *sc)
172 {
173 
174 	if (sc->gif_options & GIF_IGNORE_SOURCE)
175 		CK_LIST_INSERT_HEAD(&V_ipv6_list, sc, chain);
176 	else
177 		CK_LIST_INSERT_HEAD(&GIF_HASH_SC(sc), sc, chain);
178 
179 	CK_LIST_INSERT_HEAD(&GIF_SRCHASH(&sc->gif_ip6hdr->ip6_src),
180 	    sc, srchash);
181 }
182 
183 int
184 in6_gif_setopts(struct gif_softc *sc, u_int options)
185 {
186 
187 	/* NOTE: we are protected with gif_ioctl_sx lock */
188 	MPASS(sc->gif_family == AF_INET6);
189 	MPASS(sc->gif_options != options);
190 
191 	if ((options & GIF_IGNORE_SOURCE) !=
192 	    (sc->gif_options & GIF_IGNORE_SOURCE)) {
193 		CK_LIST_REMOVE(sc, srchash);
194 		CK_LIST_REMOVE(sc, chain);
195 		sc->gif_options = options;
196 		in6_gif_attach(sc);
197 	}
198 	return (0);
199 }
200 
201 int
202 in6_gif_ioctl(struct gif_softc *sc, u_long cmd, caddr_t data)
203 {
204 	struct in6_ifreq *ifr = (struct in6_ifreq *)data;
205 	struct sockaddr_in6 *dst, *src;
206 	struct ip6_hdr *ip6;
207 	int error;
208 
209 	/* NOTE: we are protected with gif_ioctl_sx lock */
210 	error = EINVAL;
211 	switch (cmd) {
212 	case SIOCSIFPHYADDR_IN6:
213 		src = &((struct in6_aliasreq *)data)->ifra_addr;
214 		dst = &((struct in6_aliasreq *)data)->ifra_dstaddr;
215 
216 		/* sanity checks */
217 		if (src->sin6_family != dst->sin6_family ||
218 		    src->sin6_family != AF_INET6 ||
219 		    src->sin6_len != dst->sin6_len ||
220 		    src->sin6_len != sizeof(*src))
221 			break;
222 		if (IN6_IS_ADDR_UNSPECIFIED(&src->sin6_addr) ||
223 		    IN6_IS_ADDR_UNSPECIFIED(&dst->sin6_addr)) {
224 			error = EADDRNOTAVAIL;
225 			break;
226 		}
227 		/*
228 		 * Check validity of the scope zone ID of the
229 		 * addresses, and convert it into the kernel
230 		 * internal form if necessary.
231 		 */
232 		if ((error = sa6_embedscope(src, 0)) != 0 ||
233 		    (error = sa6_embedscope(dst, 0)) != 0)
234 			break;
235 
236 		if (V_ipv6_hashtbl == NULL) {
237 			V_ipv6_hashtbl = gif_hashinit();
238 			V_ipv6_srchashtbl = gif_hashinit();
239 		}
240 		error = in6_gif_checkdup(sc, &src->sin6_addr,
241 		    &dst->sin6_addr);
242 		if (error == EADDRNOTAVAIL)
243 			break;
244 		if (error == EEXIST) {
245 			/* Addresses are the same. Just return. */
246 			error = 0;
247 			break;
248 		}
249 		ip6 = malloc(sizeof(*ip6), M_GIF, M_WAITOK | M_ZERO);
250 		ip6->ip6_src = src->sin6_addr;
251 		ip6->ip6_dst = dst->sin6_addr;
252 		ip6->ip6_vfc = IPV6_VERSION;
253 		if (sc->gif_family != 0) {
254 			/* Detach existing tunnel first */
255 			CK_LIST_REMOVE(sc, srchash);
256 			CK_LIST_REMOVE(sc, chain);
257 			GIF_WAIT();
258 			free(sc->gif_hdr, M_GIF);
259 			/* XXX: should we notify about link state change? */
260 		}
261 		sc->gif_family = AF_INET6;
262 		sc->gif_ip6hdr = ip6;
263 		in6_gif_attach(sc);
264 		in6_gif_set_running(sc);
265 		break;
266 	case SIOCGIFPSRCADDR_IN6:
267 	case SIOCGIFPDSTADDR_IN6:
268 		if (sc->gif_family != AF_INET6) {
269 			error = EADDRNOTAVAIL;
270 			break;
271 		}
272 		src = (struct sockaddr_in6 *)&ifr->ifr_addr;
273 		memset(src, 0, sizeof(*src));
274 		src->sin6_family = AF_INET6;
275 		src->sin6_len = sizeof(*src);
276 		src->sin6_addr = (cmd == SIOCGIFPSRCADDR_IN6) ?
277 		    sc->gif_ip6hdr->ip6_src: sc->gif_ip6hdr->ip6_dst;
278 		error = prison_if(curthread->td_ucred, (struct sockaddr *)src);
279 		if (error == 0)
280 			error = sa6_recoverscope(src);
281 		if (error != 0)
282 			memset(src, 0, sizeof(*src));
283 		break;
284 	}
285 	return (error);
286 }
287 
288 int
289 in6_gif_output(struct ifnet *ifp, struct mbuf *m, int proto, uint8_t ecn)
290 {
291 	struct gif_softc *sc = ifp->if_softc;
292 	struct ip6_hdr *ip6;
293 	int len;
294 
295 	/* prepend new IP header */
296 	NET_EPOCH_ASSERT();
297 	len = sizeof(struct ip6_hdr);
298 #ifndef __NO_STRICT_ALIGNMENT
299 	if (proto == IPPROTO_ETHERIP)
300 		len += ETHERIP_ALIGN;
301 #endif
302 	M_PREPEND(m, len, M_NOWAIT);
303 	if (m == NULL)
304 		return (ENOBUFS);
305 #ifndef __NO_STRICT_ALIGNMENT
306 	if (proto == IPPROTO_ETHERIP) {
307 		len = mtod(m, vm_offset_t) & 3;
308 		KASSERT(len == 0 || len == ETHERIP_ALIGN,
309 		    ("in6_gif_output: unexpected misalignment"));
310 		m->m_data += len;
311 		m->m_len -= ETHERIP_ALIGN;
312 	}
313 #endif
314 
315 	ip6 = mtod(m, struct ip6_hdr *);
316 	MPASS(sc->gif_family == AF_INET6);
317 	bcopy(sc->gif_ip6hdr, ip6, sizeof(struct ip6_hdr));
318 
319 	ip6->ip6_flow  |= htonl((uint32_t)ecn << 20);
320 	ip6->ip6_nxt	= proto;
321 	ip6->ip6_hlim	= V_ip6_gif_hlim;
322 	/*
323 	 * force fragmentation to minimum MTU, to avoid path MTU discovery.
324 	 * it is too painful to ask for resend of inner packet, to achieve
325 	 * path MTU discovery for encapsulated packets.
326 	 */
327 	return (ip6_output(m, 0, NULL, IPV6_MINMTU, 0, NULL, NULL));
328 }
329 
330 static int
331 in6_gif_input(struct mbuf *m, int off, int proto, void *arg)
332 {
333 	struct gif_softc *sc = arg;
334 	struct ifnet *gifp;
335 	struct ip6_hdr *ip6;
336 	uint8_t ecn;
337 
338 	NET_EPOCH_ASSERT();
339 	if (sc == NULL) {
340 		m_freem(m);
341 		IP6STAT_INC(ip6s_nogif);
342 		return (IPPROTO_DONE);
343 	}
344 	gifp = GIF2IFP(sc);
345 	if ((gifp->if_flags & IFF_UP) != 0) {
346 		ip6 = mtod(m, struct ip6_hdr *);
347 		ecn = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
348 		m_adj(m, off);
349 		gif_input(m, gifp, proto, ecn);
350 	} else {
351 		m_freem(m);
352 		IP6STAT_INC(ip6s_nogif);
353 	}
354 	return (IPPROTO_DONE);
355 }
356 
357 static int
358 in6_gif_lookup(const struct mbuf *m, int off, int proto, void **arg)
359 {
360 	const struct ip6_hdr *ip6;
361 	struct gif_softc *sc;
362 	int ret;
363 
364 	if (V_ipv6_hashtbl == NULL)
365 		return (0);
366 
367 	NET_EPOCH_ASSERT();
368 	/*
369 	 * NOTE: it is safe to iterate without any locking here, because softc
370 	 * can be reclaimed only when we are not within net_epoch_preempt
371 	 * section, but ip_encap lookup+input are executed in epoch section.
372 	 */
373 	ip6 = mtod(m, const struct ip6_hdr *);
374 	ret = 0;
375 	CK_LIST_FOREACH(sc, &GIF_HASH(&ip6->ip6_dst, &ip6->ip6_src), chain) {
376 		/*
377 		 * This is an inbound packet, its ip6_dst is source address
378 		 * in softc.
379 		 */
380 		if (IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_src,
381 		    &ip6->ip6_dst) &&
382 		    IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_dst,
383 		    &ip6->ip6_src)) {
384 			ret = ENCAP_DRV_LOOKUP;
385 			goto done;
386 		}
387 	}
388 	/*
389 	 * No exact match.
390 	 * Check the list of interfaces with GIF_IGNORE_SOURCE flag.
391 	 */
392 	CK_LIST_FOREACH(sc, &V_ipv6_list, chain) {
393 		if (IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_src,
394 		    &ip6->ip6_dst)) {
395 			ret = 128 + 8; /* src + proto */
396 			goto done;
397 		}
398 	}
399 	return (0);
400 done:
401 	if ((GIF2IFP(sc)->if_flags & IFF_UP) == 0)
402 		return (0);
403 	/* ingress filters on outer source */
404 	if ((GIF2IFP(sc)->if_flags & IFF_LINK2) == 0) {
405 		if (fib6_check_urpf(sc->gif_fibnum, &ip6->ip6_src,
406 		    ntohs(in6_getscope(&ip6->ip6_src)), NHR_NONE,
407 		    m->m_pkthdr.rcvif) == 0)
408 			return (0);
409 	}
410 	*arg = sc;
411 	return (ret);
412 }
413 
414 static const struct srcaddrtab *ipv6_srcaddrtab;
415 static struct {
416 	const struct encap_config encap;
417 	const struct encaptab *cookie;
418 } ipv6_encap_cfg[] = {
419 #ifdef INET
420 	{
421 		.encap = {
422 			.proto = IPPROTO_IPV4,
423 			.min_length = sizeof(struct ip6_hdr) +
424 			    sizeof(struct ip),
425 			.exact_match = ENCAP_DRV_LOOKUP,
426 			.lookup = in6_gif_lookup,
427 			.input = in6_gif_input
428 		},
429 	},
430 #endif
431 	{
432 		.encap = {
433 			.proto = IPPROTO_IPV6,
434 			.min_length = 2 * sizeof(struct ip6_hdr),
435 			.exact_match = ENCAP_DRV_LOOKUP,
436 			.lookup = in6_gif_lookup,
437 			.input = in6_gif_input
438 		},
439 	},
440 	{
441 		.encap = {
442 			.proto = IPPROTO_ETHERIP,
443 			.min_length = sizeof(struct ip6_hdr) +
444 			    sizeof(struct etherip_header) +
445 			    sizeof(struct ether_header),
446 			.exact_match = ENCAP_DRV_LOOKUP,
447 			.lookup = in6_gif_lookup,
448 			.input = in6_gif_input
449 		},
450 	}
451 };
452 
453 void
454 in6_gif_init(void)
455 {
456 	int i;
457 
458 	if (!IS_DEFAULT_VNET(curvnet))
459 		return;
460 
461 	ipv6_srcaddrtab = ip6_encap_register_srcaddr(in6_gif_srcaddr,
462 	    NULL, M_WAITOK);
463 	for (i = 0; i < nitems(ipv6_encap_cfg); i++)
464 		ipv6_encap_cfg[i].cookie = ip6_encap_attach(
465 		    &ipv6_encap_cfg[i].encap, NULL, M_WAITOK);
466 }
467 
468 void
469 in6_gif_uninit(void)
470 {
471 	int i;
472 
473 	if (IS_DEFAULT_VNET(curvnet)) {
474 		for (i = 0; i < nitems(ipv6_encap_cfg); i++)
475 			ip6_encap_detach(ipv6_encap_cfg[i].cookie);
476 		ip6_encap_unregister_srcaddr(ipv6_srcaddrtab);
477 	}
478 	if (V_ipv6_hashtbl != NULL) {
479 		gif_hashdestroy(V_ipv6_hashtbl);
480 		V_ipv6_hashtbl = NULL;
481 		GIF_WAIT();
482 		gif_hashdestroy(V_ipv6_srchashtbl);
483 	}
484 }
485