xref: /freebsd/sys/netinet/in_gif.c (revision 0a36787e4c1fa0cf77dcf83be0867178476e372b) 
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 __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/sysctl.h>
50 #include <sys/malloc.h>
51 #include <sys/proc.h>
52 
53 #include <net/ethernet.h>
54 #include <net/if.h>
55 #include <net/if_var.h>
56 #include <net/route.h>
57 #include <net/vnet.h>
58 
59 #include <netinet/in.h>
60 #include <netinet/in_systm.h>
61 #include <netinet/ip.h>
62 #include <netinet/ip_var.h>
63 #include <netinet/in_var.h>
64 #include <netinet/ip_encap.h>
65 #include <netinet/ip_ecn.h>
66 #include <netinet/in_fib.h>
67 
68 #ifdef INET6
69 #include <netinet/ip6.h>
70 #endif
71 
72 #include <net/if_gif.h>
73 
74 #define GIF_TTL		30
75 VNET_DEFINE_STATIC(int, ip_gif_ttl) = GIF_TTL;
76 #define	V_ip_gif_ttl		VNET(ip_gif_ttl)
77 SYSCTL_INT(_net_inet_ip, IPCTL_GIF_TTL, gifttl, CTLFLAG_VNET | CTLFLAG_RW,
78     &VNET_NAME(ip_gif_ttl), 0, "Default TTL value for encapsulated packets");
79 
80 /*
81  * We keep interfaces in a hash table using src+dst as key.
82  * Interfaces with GIF_IGNORE_SOURCE flag are linked into plain list.
83  */
84 VNET_DEFINE_STATIC(struct gif_list *, ipv4_hashtbl) = NULL;
85 VNET_DEFINE_STATIC(struct gif_list *, ipv4_srchashtbl) = NULL;
86 VNET_DEFINE_STATIC(struct gif_list, ipv4_list) = CK_LIST_HEAD_INITIALIZER();
87 #define	V_ipv4_hashtbl		VNET(ipv4_hashtbl)
88 #define	V_ipv4_srchashtbl	VNET(ipv4_srchashtbl)
89 #define	V_ipv4_list		VNET(ipv4_list)
90 
91 #define	GIF_HASH(src, dst)	(V_ipv4_hashtbl[\
92     in_gif_hashval((src), (dst)) & (GIF_HASH_SIZE - 1)])
93 #define	GIF_SRCHASH(src)	(V_ipv4_srchashtbl[\
94     fnv_32_buf(&(src), sizeof(src), FNV1_32_INIT) & (GIF_HASH_SIZE - 1)])
95 #define	GIF_HASH_SC(sc)		GIF_HASH((sc)->gif_iphdr->ip_src.s_addr,\
96     (sc)->gif_iphdr->ip_dst.s_addr)
97 static uint32_t
98 in_gif_hashval(in_addr_t src, in_addr_t dst)
99 {
100 	uint32_t ret;
101 
102 	ret = fnv_32_buf(&src, sizeof(src), FNV1_32_INIT);
103 	return (fnv_32_buf(&dst, sizeof(dst), ret));
104 }
105 
106 static int
107 in_gif_checkdup(const struct gif_softc *sc, in_addr_t src, in_addr_t dst)
108 {
109 	struct gif_softc *tmp;
110 
111 	if (sc->gif_family == AF_INET &&
112 	    sc->gif_iphdr->ip_src.s_addr == src &&
113 	    sc->gif_iphdr->ip_dst.s_addr == dst)
114 		return (EEXIST);
115 
116 	CK_LIST_FOREACH(tmp, &GIF_HASH(src, dst), chain) {
117 		if (tmp == sc)
118 			continue;
119 		if (tmp->gif_iphdr->ip_src.s_addr == src &&
120 		    tmp->gif_iphdr->ip_dst.s_addr == dst)
121 			return (EADDRNOTAVAIL);
122 	}
123 	return (0);
124 }
125 
126 /*
127  * Check that ingress address belongs to local host.
128  */
129 static void
130 in_gif_set_running(struct gif_softc *sc)
131 {
132 
133 	if (in_localip(sc->gif_iphdr->ip_src))
134 		GIF2IFP(sc)->if_drv_flags |= IFF_DRV_RUNNING;
135 	else
136 		GIF2IFP(sc)->if_drv_flags &= ~IFF_DRV_RUNNING;
137 }
138 
139 /*
140  * ifaddr_event handler.
141  * Clear IFF_DRV_RUNNING flag when ingress address disappears to prevent
142  * source address spoofing.
143  */
144 static void
145 in_gif_srcaddr(void *arg __unused, const struct sockaddr *sa,
146     int event __unused)
147 {
148 	const struct sockaddr_in *sin;
149 	struct gif_softc *sc;
150 
151 	/* Check that VNET is ready */
152 	if (V_ipv4_hashtbl == NULL)
153 		return;
154 
155 	NET_EPOCH_ASSERT();
156 	sin = (const struct sockaddr_in *)sa;
157 	CK_LIST_FOREACH(sc, &GIF_SRCHASH(sin->sin_addr.s_addr), srchash) {
158 		if (sc->gif_iphdr->ip_src.s_addr != sin->sin_addr.s_addr)
159 			continue;
160 		in_gif_set_running(sc);
161 	}
162 }
163 
164 static void
165 in_gif_attach(struct gif_softc *sc)
166 {
167 
168 	if (sc->gif_options & GIF_IGNORE_SOURCE)
169 		CK_LIST_INSERT_HEAD(&V_ipv4_list, sc, chain);
170 	else
171 		CK_LIST_INSERT_HEAD(&GIF_HASH_SC(sc), sc, chain);
172 
173 	CK_LIST_INSERT_HEAD(&GIF_SRCHASH(sc->gif_iphdr->ip_src.s_addr),
174 	    sc, srchash);
175 }
176 
177 int
178 in_gif_setopts(struct gif_softc *sc, u_int options)
179 {
180 
181 	/* NOTE: we are protected with gif_ioctl_sx lock */
182 	MPASS(sc->gif_family == AF_INET);
183 	MPASS(sc->gif_options != options);
184 
185 	if ((options & GIF_IGNORE_SOURCE) !=
186 	    (sc->gif_options & GIF_IGNORE_SOURCE)) {
187 		CK_LIST_REMOVE(sc, srchash);
188 		CK_LIST_REMOVE(sc, chain);
189 		sc->gif_options = options;
190 		in_gif_attach(sc);
191 	}
192 	return (0);
193 }
194 
195 int
196 in_gif_ioctl(struct gif_softc *sc, u_long cmd, caddr_t data)
197 {
198 	struct ifreq *ifr = (struct ifreq *)data;
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 		in_gif_set_running(sc);
249 		break;
250 	case SIOCGIFPSRCADDR:
251 	case SIOCGIFPDSTADDR:
252 		if (sc->gif_family != AF_INET) {
253 			error = EADDRNOTAVAIL;
254 			break;
255 		}
256 		src = (struct sockaddr_in *)&ifr->ifr_addr;
257 		memset(src, 0, sizeof(*src));
258 		src->sin_family = AF_INET;
259 		src->sin_len = sizeof(*src);
260 		src->sin_addr = (cmd == SIOCGIFPSRCADDR) ?
261 		    sc->gif_iphdr->ip_src: sc->gif_iphdr->ip_dst;
262 		error = prison_if(curthread->td_ucred, (struct sockaddr *)src);
263 		if (error != 0)
264 			memset(src, 0, sizeof(*src));
265 		break;
266 	}
267 	return (error);
268 }
269 
270 int
271 in_gif_output(struct ifnet *ifp, struct mbuf *m, int proto, uint8_t ecn)
272 {
273 	struct gif_softc *sc = ifp->if_softc;
274 	struct ip *ip;
275 	int len;
276 
277 	/* prepend new IP header */
278 	NET_EPOCH_ASSERT();
279 	len = sizeof(struct ip);
280 #ifndef __NO_STRICT_ALIGNMENT
281 	if (proto == IPPROTO_ETHERIP)
282 		len += ETHERIP_ALIGN;
283 #endif
284 	M_PREPEND(m, len, M_NOWAIT);
285 	if (m == NULL)
286 		return (ENOBUFS);
287 #ifndef __NO_STRICT_ALIGNMENT
288 	if (proto == IPPROTO_ETHERIP) {
289 		len = mtod(m, vm_offset_t) & 3;
290 		KASSERT(len == 0 || len == ETHERIP_ALIGN,
291 		    ("in_gif_output: unexpected misalignment"));
292 		m->m_data += len;
293 		m->m_len -= ETHERIP_ALIGN;
294 	}
295 #endif
296 	ip = mtod(m, struct ip *);
297 
298 	MPASS(sc->gif_family == AF_INET);
299 	bcopy(sc->gif_iphdr, ip, sizeof(struct ip));
300 	ip->ip_p = proto;
301 	/* version will be set in ip_output() */
302 	ip->ip_ttl = V_ip_gif_ttl;
303 	ip->ip_len = htons(m->m_pkthdr.len);
304 	ip->ip_tos = ecn;
305 
306 	return (ip_output(m, NULL, NULL, 0, NULL, NULL));
307 }
308 
309 static int
310 in_gif_input(struct mbuf *m, int off, int proto, void *arg)
311 {
312 	struct gif_softc *sc = arg;
313 	struct ifnet *gifp;
314 	struct ip *ip;
315 	uint8_t ecn;
316 
317 	NET_EPOCH_ASSERT();
318 	if (sc == NULL) {
319 		m_freem(m);
320 		KMOD_IPSTAT_INC(ips_nogif);
321 		return (IPPROTO_DONE);
322 	}
323 	gifp = GIF2IFP(sc);
324 	if ((gifp->if_flags & IFF_UP) != 0) {
325 		ip = mtod(m, struct ip *);
326 		ecn = ip->ip_tos;
327 		m_adj(m, off);
328 		gif_input(m, gifp, proto, ecn);
329 	} else {
330 		m_freem(m);
331 		KMOD_IPSTAT_INC(ips_nogif);
332 	}
333 	return (IPPROTO_DONE);
334 }
335 
336 static int
337 in_gif_lookup(const struct mbuf *m, int off, int proto, void **arg)
338 {
339 	const struct ip *ip;
340 	struct gif_softc *sc;
341 	int ret;
342 
343 	if (V_ipv4_hashtbl == NULL)
344 		return (0);
345 
346 	NET_EPOCH_ASSERT();
347 	ip = mtod(m, const struct ip *);
348 	/*
349 	 * NOTE: it is safe to iterate without any locking here, because softc
350 	 * can be reclaimed only when we are not within net_epoch_preempt
351 	 * section, but ip_encap lookup+input are executed in epoch section.
352 	 */
353 	ret = 0;
354 	CK_LIST_FOREACH(sc, &GIF_HASH(ip->ip_dst.s_addr,
355 	    ip->ip_src.s_addr), chain) {
356 		/*
357 		 * This is an inbound packet, its ip_dst is source address
358 		 * in softc.
359 		 */
360 		if (sc->gif_iphdr->ip_src.s_addr == ip->ip_dst.s_addr &&
361 		    sc->gif_iphdr->ip_dst.s_addr == ip->ip_src.s_addr) {
362 			ret = ENCAP_DRV_LOOKUP;
363 			goto done;
364 		}
365 	}
366 	/*
367 	 * No exact match.
368 	 * Check the list of interfaces with GIF_IGNORE_SOURCE flag.
369 	 */
370 	CK_LIST_FOREACH(sc, &V_ipv4_list, chain) {
371 		if (sc->gif_iphdr->ip_src.s_addr == ip->ip_dst.s_addr) {
372 			ret = 32 + 8; /* src + proto */
373 			goto done;
374 		}
375 	}
376 	return (0);
377 done:
378 	if ((GIF2IFP(sc)->if_flags & IFF_UP) == 0)
379 		return (0);
380 	/* ingress filters on outer source */
381 	if ((GIF2IFP(sc)->if_flags & IFF_LINK2) == 0) {
382 		if (fib4_check_urpf(sc->gif_fibnum, ip->ip_src, 0, NHR_NONE,
383 					m->m_pkthdr.rcvif) == 0)
384 			return (0);
385 	}
386 	*arg = sc;
387 	return (ret);
388 }
389 
390 static const struct srcaddrtab *ipv4_srcaddrtab;
391 static struct {
392 	const struct encap_config encap;
393 	const struct encaptab *cookie;
394 } ipv4_encap_cfg[] = {
395 	{
396 		.encap = {
397 			.proto = IPPROTO_IPV4,
398 			.min_length = 2 * sizeof(struct ip),
399 			.exact_match = ENCAP_DRV_LOOKUP,
400 			.lookup = in_gif_lookup,
401 			.input = in_gif_input
402 		},
403 	},
404 #ifdef INET6
405 	{
406 		.encap = {
407 			.proto = IPPROTO_IPV6,
408 			.min_length = sizeof(struct ip) +
409 			    sizeof(struct ip6_hdr),
410 			.exact_match = ENCAP_DRV_LOOKUP,
411 			.lookup = in_gif_lookup,
412 			.input = in_gif_input
413 		},
414 	},
415 #endif
416 	{
417 		.encap = {
418 			.proto = IPPROTO_ETHERIP,
419 			.min_length = sizeof(struct ip) +
420 			    sizeof(struct etherip_header) +
421 			    sizeof(struct ether_header),
422 			.exact_match = ENCAP_DRV_LOOKUP,
423 			.lookup = in_gif_lookup,
424 			.input = in_gif_input
425 		},
426 	}
427 };
428 
429 void
430 in_gif_init(void)
431 {
432 	int i;
433 
434 	if (!IS_DEFAULT_VNET(curvnet))
435 		return;
436 
437 	ipv4_srcaddrtab = ip_encap_register_srcaddr(in_gif_srcaddr,
438 	    NULL, M_WAITOK);
439 	for (i = 0; i < nitems(ipv4_encap_cfg); i++)
440 		ipv4_encap_cfg[i].cookie = ip_encap_attach(
441 		    &ipv4_encap_cfg[i].encap, NULL, M_WAITOK);
442 }
443 
444 void
445 in_gif_uninit(void)
446 {
447 	int i;
448 
449 	if (IS_DEFAULT_VNET(curvnet)) {
450 		for (i = 0; i < nitems(ipv4_encap_cfg); i++)
451 			ip_encap_detach(ipv4_encap_cfg[i].cookie);
452 		ip_encap_unregister_srcaddr(ipv4_srcaddrtab);
453 	}
454 	if (V_ipv4_hashtbl != NULL) {
455 		gif_hashdestroy(V_ipv4_hashtbl);
456 		V_ipv4_hashtbl = NULL;
457 		GIF_WAIT();
458 		gif_hashdestroy(V_ipv4_srchashtbl);
459 	}
460 }
461