xref: /freebsd/sys/netinet/in_gif.c (revision 069ac184) 
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: in_gif.c,v 1.54 2001/05/14 14:02:16 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/sysctl.h>
48 #include <sys/malloc.h>
49 #include <sys/proc.h>
50 
51 #include <net/ethernet.h>
52 #include <net/if.h>
53 #include <net/if_var.h>
54 #include <net/if_private.h>
55 #include <net/route.h>
56 #include <net/vnet.h>
57 
58 #include <netinet/in.h>
59 #include <netinet/in_systm.h>
60 #include <netinet/ip.h>
61 #include <netinet/ip_var.h>
62 #include <netinet/in_var.h>
63 #include <netinet/ip_encap.h>
64 #include <netinet/ip_ecn.h>
65 #include <netinet/in_fib.h>
66 
67 #ifdef INET6
68 #include <netinet/ip6.h>
69 #endif
70 
71 #include <net/if_gif.h>
72 
73 #define GIF_TTL		30
74 VNET_DEFINE_STATIC(int, ip_gif_ttl) = GIF_TTL;
75 #define	V_ip_gif_ttl		VNET(ip_gif_ttl)
76 SYSCTL_INT(_net_inet_ip, IPCTL_GIF_TTL, gifttl, CTLFLAG_VNET | CTLFLAG_RW,
77     &VNET_NAME(ip_gif_ttl), 0, "Default TTL value for encapsulated packets");
78 
79 /*
80  * We keep interfaces in a hash table using src+dst as key.
81  * Interfaces with GIF_IGNORE_SOURCE flag are linked into plain list.
82  */
83 VNET_DEFINE_STATIC(struct gif_list *, ipv4_hashtbl) = NULL;
84 VNET_DEFINE_STATIC(struct gif_list *, ipv4_srchashtbl) = NULL;
85 VNET_DEFINE_STATIC(struct gif_list, ipv4_list) = CK_LIST_HEAD_INITIALIZER();
86 #define	V_ipv4_hashtbl		VNET(ipv4_hashtbl)
87 #define	V_ipv4_srchashtbl	VNET(ipv4_srchashtbl)
88 #define	V_ipv4_list		VNET(ipv4_list)
89 
90 #define	GIF_HASH(src, dst)	(V_ipv4_hashtbl[\
91     in_gif_hashval((src), (dst)) & (GIF_HASH_SIZE - 1)])
92 #define	GIF_SRCHASH(src)	(V_ipv4_srchashtbl[\
93     fnv_32_buf(&(src), sizeof(src), FNV1_32_INIT) & (GIF_HASH_SIZE - 1)])
94 #define	GIF_HASH_SC(sc)		GIF_HASH((sc)->gif_iphdr->ip_src.s_addr,\
95     (sc)->gif_iphdr->ip_dst.s_addr)
96 static uint32_t
97 in_gif_hashval(in_addr_t src, in_addr_t dst)
98 {
99 	uint32_t ret;
100 
101 	ret = fnv_32_buf(&src, sizeof(src), FNV1_32_INIT);
102 	return (fnv_32_buf(&dst, sizeof(dst), ret));
103 }
104 
105 static int
106 in_gif_checkdup(const struct gif_softc *sc, in_addr_t src, in_addr_t dst)
107 {
108 	struct gif_softc *tmp;
109 
110 	if (sc->gif_family == AF_INET &&
111 	    sc->gif_iphdr->ip_src.s_addr == src &&
112 	    sc->gif_iphdr->ip_dst.s_addr == dst)
113 		return (EEXIST);
114 
115 	CK_LIST_FOREACH(tmp, &GIF_HASH(src, dst), chain) {
116 		if (tmp == sc)
117 			continue;
118 		if (tmp->gif_iphdr->ip_src.s_addr == src &&
119 		    tmp->gif_iphdr->ip_dst.s_addr == dst)
120 			return (EADDRNOTAVAIL);
121 	}
122 	return (0);
123 }
124 
125 /*
126  * Check that ingress address belongs to local host.
127  */
128 static void
129 in_gif_set_running(struct gif_softc *sc)
130 {
131 
132 	if (in_localip(sc->gif_iphdr->ip_src))
133 		GIF2IFP(sc)->if_drv_flags |= IFF_DRV_RUNNING;
134 	else
135 		GIF2IFP(sc)->if_drv_flags &= ~IFF_DRV_RUNNING;
136 }
137 
138 /*
139  * ifaddr_event handler.
140  * Clear IFF_DRV_RUNNING flag when ingress address disappears to prevent
141  * source address spoofing.
142  */
143 static void
144 in_gif_srcaddr(void *arg __unused, const struct sockaddr *sa,
145     int event __unused)
146 {
147 	const struct sockaddr_in *sin;
148 	struct gif_softc *sc;
149 
150 	/* Check that VNET is ready */
151 	if (V_ipv4_hashtbl == NULL)
152 		return;
153 
154 	NET_EPOCH_ASSERT();
155 	sin = (const struct sockaddr_in *)sa;
156 	CK_LIST_FOREACH(sc, &GIF_SRCHASH(sin->sin_addr.s_addr), srchash) {
157 		if (sc->gif_iphdr->ip_src.s_addr != sin->sin_addr.s_addr)
158 			continue;
159 		in_gif_set_running(sc);
160 	}
161 }
162 
163 static void
164 in_gif_attach(struct gif_softc *sc)
165 {
166 
167 	if (sc->gif_options & GIF_IGNORE_SOURCE)
168 		CK_LIST_INSERT_HEAD(&V_ipv4_list, sc, chain);
169 	else
170 		CK_LIST_INSERT_HEAD(&GIF_HASH_SC(sc), sc, chain);
171 
172 	CK_LIST_INSERT_HEAD(&GIF_SRCHASH(sc->gif_iphdr->ip_src.s_addr),
173 	    sc, srchash);
174 }
175 
176 int
177 in_gif_setopts(struct gif_softc *sc, u_int options)
178 {
179 
180 	/* NOTE: we are protected with gif_ioctl_sx lock */
181 	MPASS(sc->gif_family == AF_INET);
182 	MPASS(sc->gif_options != options);
183 
184 	if ((options & GIF_IGNORE_SOURCE) !=
185 	    (sc->gif_options & GIF_IGNORE_SOURCE)) {
186 		CK_LIST_REMOVE(sc, srchash);
187 		CK_LIST_REMOVE(sc, chain);
188 		sc->gif_options = options;
189 		in_gif_attach(sc);
190 	}
191 	return (0);
192 }
193 
194 int
195 in_gif_ioctl(struct gif_softc *sc, u_long cmd, caddr_t data)
196 {
197 	struct ifreq *ifr = (struct ifreq *)data;
198 	struct epoch_tracker et;
199 	struct sockaddr_in *dst, *src;
200 	struct ip *ip;
201 	int error;
202 
203 	/* NOTE: we are protected with gif_ioctl_sx lock */
204 	error = EINVAL;
205 	switch (cmd) {
206 	case SIOCSIFPHYADDR:
207 		src = &((struct in_aliasreq *)data)->ifra_addr;
208 		dst = &((struct in_aliasreq *)data)->ifra_dstaddr;
209 
210 		/* sanity checks */
211 		if (src->sin_family != dst->sin_family ||
212 		    src->sin_family != AF_INET ||
213 		    src->sin_len != dst->sin_len ||
214 		    src->sin_len != sizeof(*src))
215 			break;
216 		if (src->sin_addr.s_addr == INADDR_ANY ||
217 		    dst->sin_addr.s_addr == INADDR_ANY) {
218 			error = EADDRNOTAVAIL;
219 			break;
220 		}
221 		if (V_ipv4_hashtbl == NULL) {
222 			V_ipv4_hashtbl = gif_hashinit();
223 			V_ipv4_srchashtbl = gif_hashinit();
224 		}
225 		error = in_gif_checkdup(sc, src->sin_addr.s_addr,
226 		    dst->sin_addr.s_addr);
227 		if (error == EADDRNOTAVAIL)
228 			break;
229 		if (error == EEXIST) {
230 			/* Addresses are the same. Just return. */
231 			error = 0;
232 			break;
233 		}
234 		ip = malloc(sizeof(*ip), M_GIF, M_WAITOK | M_ZERO);
235 		ip->ip_src.s_addr = src->sin_addr.s_addr;
236 		ip->ip_dst.s_addr = dst->sin_addr.s_addr;
237 		if (sc->gif_family != 0) {
238 			/* Detach existing tunnel first */
239 			CK_LIST_REMOVE(sc, srchash);
240 			CK_LIST_REMOVE(sc, chain);
241 			GIF_WAIT();
242 			free(sc->gif_hdr, M_GIF);
243 			/* XXX: should we notify about link state change? */
244 		}
245 		sc->gif_family = AF_INET;
246 		sc->gif_iphdr = ip;
247 		in_gif_attach(sc);
248 		NET_EPOCH_ENTER(et);
249 		in_gif_set_running(sc);
250 		NET_EPOCH_EXIT(et);
251 		break;
252 	case SIOCGIFPSRCADDR:
253 	case SIOCGIFPDSTADDR:
254 		if (sc->gif_family != AF_INET) {
255 			error = EADDRNOTAVAIL;
256 			break;
257 		}
258 		src = (struct sockaddr_in *)&ifr->ifr_addr;
259 		memset(src, 0, sizeof(*src));
260 		src->sin_family = AF_INET;
261 		src->sin_len = sizeof(*src);
262 		src->sin_addr = (cmd == SIOCGIFPSRCADDR) ?
263 		    sc->gif_iphdr->ip_src: sc->gif_iphdr->ip_dst;
264 		error = prison_if(curthread->td_ucred, (struct sockaddr *)src);
265 		if (error != 0)
266 			memset(src, 0, sizeof(*src));
267 		break;
268 	}
269 	return (error);
270 }
271 
272 int
273 in_gif_output(struct ifnet *ifp, struct mbuf *m, int proto, uint8_t ecn)
274 {
275 	struct gif_softc *sc = ifp->if_softc;
276 	struct ip *ip;
277 
278 	/* prepend new IP header */
279 	NET_EPOCH_ASSERT();
280 	M_PREPEND(m, sizeof(struct ip), M_NOWAIT);
281 	if (m == NULL)
282 		return (ENOBUFS);
283 	ip = mtod(m, struct ip *);
284 
285 	MPASS(sc->gif_family == AF_INET);
286 	memcpy(ip, sc->gif_iphdr, sizeof(struct ip));
287 	ip->ip_p = proto;
288 	/* version will be set in ip_output() */
289 	ip->ip_ttl = V_ip_gif_ttl;
290 	ip->ip_len = htons(m->m_pkthdr.len);
291 	ip->ip_tos = ecn;
292 
293 	return (ip_output(m, NULL, NULL, 0, NULL, NULL));
294 }
295 
296 static int
297 in_gif_input(struct mbuf *m, int off, int proto, void *arg)
298 {
299 	struct gif_softc *sc = arg;
300 	struct ifnet *gifp;
301 	struct ip *ip;
302 	uint8_t ecn;
303 
304 	NET_EPOCH_ASSERT();
305 	if (sc == NULL) {
306 		m_freem(m);
307 		KMOD_IPSTAT_INC(ips_nogif);
308 		return (IPPROTO_DONE);
309 	}
310 	gifp = GIF2IFP(sc);
311 	if ((gifp->if_flags & IFF_UP) != 0) {
312 		ip = mtod(m, struct ip *);
313 		ecn = ip->ip_tos;
314 		m_adj(m, off);
315 		gif_input(m, gifp, proto, ecn);
316 	} else {
317 		m_freem(m);
318 		KMOD_IPSTAT_INC(ips_nogif);
319 	}
320 	return (IPPROTO_DONE);
321 }
322 
323 static int
324 in_gif_lookup(const struct mbuf *m, int off, int proto, void **arg)
325 {
326 	const struct ip *ip;
327 	struct gif_softc *sc;
328 	int ret;
329 
330 	if (V_ipv4_hashtbl == NULL)
331 		return (0);
332 
333 	NET_EPOCH_ASSERT();
334 	ip = mtod(m, const struct ip *);
335 	/*
336 	 * NOTE: it is safe to iterate without any locking here, because softc
337 	 * can be reclaimed only when we are not within net_epoch_preempt
338 	 * section, but ip_encap lookup+input are executed in epoch section.
339 	 */
340 	ret = 0;
341 	CK_LIST_FOREACH(sc, &GIF_HASH(ip->ip_dst.s_addr,
342 	    ip->ip_src.s_addr), chain) {
343 		/*
344 		 * This is an inbound packet, its ip_dst is source address
345 		 * in softc.
346 		 */
347 		if (sc->gif_iphdr->ip_src.s_addr == ip->ip_dst.s_addr &&
348 		    sc->gif_iphdr->ip_dst.s_addr == ip->ip_src.s_addr) {
349 			ret = ENCAP_DRV_LOOKUP;
350 			goto done;
351 		}
352 	}
353 	/*
354 	 * No exact match.
355 	 * Check the list of interfaces with GIF_IGNORE_SOURCE flag.
356 	 */
357 	CK_LIST_FOREACH(sc, &V_ipv4_list, chain) {
358 		if (sc->gif_iphdr->ip_src.s_addr == ip->ip_dst.s_addr) {
359 			ret = 32 + 8; /* src + proto */
360 			goto done;
361 		}
362 	}
363 	return (0);
364 done:
365 	if ((GIF2IFP(sc)->if_flags & IFF_UP) == 0)
366 		return (0);
367 	/* ingress filters on outer source */
368 	if ((GIF2IFP(sc)->if_flags & IFF_LINK2) == 0) {
369 		if (fib4_check_urpf(sc->gif_fibnum, ip->ip_src, 0, NHR_NONE,
370 					m->m_pkthdr.rcvif) == 0)
371 			return (0);
372 	}
373 	*arg = sc;
374 	return (ret);
375 }
376 
377 static const struct srcaddrtab *ipv4_srcaddrtab;
378 static struct {
379 	const struct encap_config encap;
380 	const struct encaptab *cookie;
381 } ipv4_encap_cfg[] = {
382 	{
383 		.encap = {
384 			.proto = IPPROTO_IPV4,
385 			.min_length = 2 * sizeof(struct ip),
386 			.exact_match = ENCAP_DRV_LOOKUP,
387 			.lookup = in_gif_lookup,
388 			.input = in_gif_input
389 		},
390 	},
391 #ifdef INET6
392 	{
393 		.encap = {
394 			.proto = IPPROTO_IPV6,
395 			.min_length = sizeof(struct ip) +
396 			    sizeof(struct ip6_hdr),
397 			.exact_match = ENCAP_DRV_LOOKUP,
398 			.lookup = in_gif_lookup,
399 			.input = in_gif_input
400 		},
401 	},
402 #endif
403 	{
404 		.encap = {
405 			.proto = IPPROTO_ETHERIP,
406 			.min_length = sizeof(struct ip) +
407 			    sizeof(struct etherip_header) +
408 			    sizeof(struct ether_header),
409 			.exact_match = ENCAP_DRV_LOOKUP,
410 			.lookup = in_gif_lookup,
411 			.input = in_gif_input
412 		},
413 	}
414 };
415 
416 void
417 in_gif_init(void)
418 {
419 	int i;
420 
421 	if (!IS_DEFAULT_VNET(curvnet))
422 		return;
423 
424 	ipv4_srcaddrtab = ip_encap_register_srcaddr(in_gif_srcaddr,
425 	    NULL, M_WAITOK);
426 	for (i = 0; i < nitems(ipv4_encap_cfg); i++)
427 		ipv4_encap_cfg[i].cookie = ip_encap_attach(
428 		    &ipv4_encap_cfg[i].encap, NULL, M_WAITOK);
429 }
430 
431 void
432 in_gif_uninit(void)
433 {
434 	int i;
435 
436 	if (IS_DEFAULT_VNET(curvnet)) {
437 		for (i = 0; i < nitems(ipv4_encap_cfg); i++)
438 			ip_encap_detach(ipv4_encap_cfg[i].cookie);
439 		ip_encap_unregister_srcaddr(ipv4_srcaddrtab);
440 	}
441 	if (V_ipv4_hashtbl != NULL) {
442 		gif_hashdestroy(V_ipv4_hashtbl);
443 		V_ipv4_hashtbl = NULL;
444 		GIF_WAIT();
445 		gif_hashdestroy(V_ipv4_srchashtbl);
446 	}
447 }
448