xref: /freebsd/sys/net/if_loop.c (revision 74bf4e164ba5851606a27d4feff27717452583e5)
1 /*
2  * Copyright (c) 1982, 1986, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	@(#)if_loop.c	8.2 (Berkeley) 1/9/95
30  * $FreeBSD$
31  */
32 
33 /*
34  * Loopback interface driver for protocol testing and timing.
35  */
36 
37 #include "opt_atalk.h"
38 #include "opt_inet.h"
39 #include "opt_inet6.h"
40 #include "opt_ipx.h"
41 
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/kernel.h>
45 #include <sys/malloc.h>
46 #include <sys/mbuf.h>
47 #include <sys/module.h>
48 #include <machine/bus.h>
49 #include <sys/rman.h>
50 #include <sys/socket.h>
51 #include <sys/sockio.h>
52 #include <sys/sysctl.h>
53 
54 #include <net/if.h>
55 #include <net/if_clone.h>
56 #include <net/if_types.h>
57 #include <net/netisr.h>
58 #include <net/route.h>
59 #include <net/bpf.h>
60 #include <net/bpfdesc.h>
61 
62 #ifdef	INET
63 #include <netinet/in.h>
64 #include <netinet/in_var.h>
65 #endif
66 
67 #ifdef IPX
68 #include <netipx/ipx.h>
69 #include <netipx/ipx_if.h>
70 #endif
71 
72 #ifdef INET6
73 #ifndef INET
74 #include <netinet/in.h>
75 #endif
76 #include <netinet6/in6_var.h>
77 #include <netinet/ip6.h>
78 #endif
79 
80 #ifdef NETATALK
81 #include <netatalk/at.h>
82 #include <netatalk/at_var.h>
83 #endif
84 
85 #ifdef TINY_LOMTU
86 #define	LOMTU	(1024+512)
87 #elif defined(LARGE_LOMTU)
88 #define LOMTU	131072
89 #else
90 #define LOMTU	16384
91 #endif
92 
93 #define LONAME	"lo"
94 
95 struct lo_softc {
96 	struct	ifnet sc_if;		/* network-visible interface */
97 	LIST_ENTRY(lo_softc) sc_next;
98 };
99 
100 int		loioctl(struct ifnet *, u_long, caddr_t);
101 static void	lortrequest(int, struct rtentry *, struct rt_addrinfo *);
102 int		looutput(struct ifnet *ifp, struct mbuf *m,
103 		    struct sockaddr *dst, struct rtentry *rt);
104 static int	lo_clone_create(struct if_clone *, int);
105 static void	lo_clone_destroy(struct ifnet *);
106 
107 struct ifnet *loif = NULL;			/* Used externally */
108 
109 static MALLOC_DEFINE(M_LO, LONAME, "Loopback Interface");
110 
111 static struct mtx lo_mtx;
112 static LIST_HEAD(lo_list, lo_softc) lo_list;
113 
114 IFC_SIMPLE_DECLARE(lo, 1);
115 
116 static void
117 lo_clone_destroy(ifp)
118 	struct ifnet *ifp;
119 {
120 	struct lo_softc *sc;
121 
122 	sc = ifp->if_softc;
123 
124 	/* XXX: destroying lo0 will lead to panics. */
125 	KASSERT(loif != ifp, ("%s: destroying lo0", __func__));
126 
127 	mtx_lock(&lo_mtx);
128 	LIST_REMOVE(sc, sc_next);
129 	mtx_unlock(&lo_mtx);
130 	bpfdetach(ifp);
131 	if_detach(ifp);
132 	free(sc, M_LO);
133 }
134 
135 static int
136 lo_clone_create(ifc, unit)
137 	struct if_clone *ifc;
138 	int unit;
139 {
140 	struct lo_softc *sc;
141 
142 	MALLOC(sc, struct lo_softc *, sizeof(*sc), M_LO, M_WAITOK | M_ZERO);
143 
144 	if_initname(&sc->sc_if, ifc->ifc_name, unit);
145 	sc->sc_if.if_mtu = LOMTU;
146 	sc->sc_if.if_flags = IFF_LOOPBACK | IFF_MULTICAST;
147 	sc->sc_if.if_ioctl = loioctl;
148 	sc->sc_if.if_output = looutput;
149 	sc->sc_if.if_type = IFT_LOOP;
150 	sc->sc_if.if_snd.ifq_maxlen = ifqmaxlen;
151 	sc->sc_if.if_softc = sc;
152 	if_attach(&sc->sc_if);
153 	bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
154 	mtx_lock(&lo_mtx);
155 	LIST_INSERT_HEAD(&lo_list, sc, sc_next);
156 	mtx_unlock(&lo_mtx);
157 	if (loif == NULL)
158 		loif = &sc->sc_if;
159 
160 	return (0);
161 }
162 
163 static int
164 loop_modevent(module_t mod, int type, void *data)
165 {
166 	switch (type) {
167 	case MOD_LOAD:
168 		mtx_init(&lo_mtx, "lo_mtx", NULL, MTX_DEF);
169 		LIST_INIT(&lo_list);
170 		if_clone_attach(&lo_cloner);
171 		break;
172 	case MOD_UNLOAD:
173 		printf("loop module unload - not possible for this module type\n");
174 		return EINVAL;
175 	default:
176 		return EOPNOTSUPP;
177 	}
178 	return 0;
179 }
180 
181 static moduledata_t loop_mod = {
182 	"loop",
183 	loop_modevent,
184 	0
185 };
186 
187 DECLARE_MODULE(loop, loop_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
188 
189 int
190 looutput(ifp, m, dst, rt)
191 	struct ifnet *ifp;
192 	register struct mbuf *m;
193 	struct sockaddr *dst;
194 	register struct rtentry *rt;
195 {
196 	M_ASSERTPKTHDR(m); /* check if we have the packet header */
197 
198 	if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
199 		m_freem(m);
200 		return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
201 		        rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
202 	}
203 
204 	ifp->if_opackets++;
205 	ifp->if_obytes += m->m_pkthdr.len;
206 #if 1	/* XXX */
207 	switch (dst->sa_family) {
208 	case AF_INET:
209 	case AF_INET6:
210 	case AF_IPX:
211 	case AF_APPLETALK:
212 		break;
213 	default:
214 		printf("looutput: af=%d unexpected\n", dst->sa_family);
215 		m_freem(m);
216 		return (EAFNOSUPPORT);
217 	}
218 #endif
219 	return(if_simloop(ifp, m, dst->sa_family, 0));
220 }
221 
222 /*
223  * if_simloop()
224  *
225  * This function is to support software emulation of hardware loopback,
226  * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
227  * hear their own broadcasts, we create a copy of the packet that we
228  * would normally receive via a hardware loopback.
229  *
230  * This function expects the packet to include the media header of length hlen.
231  */
232 
233 int
234 if_simloop(ifp, m, af, hlen)
235 	struct ifnet *ifp;
236 	struct mbuf *m;
237 	int af;
238 	int hlen;
239 {
240 	int isr;
241 
242 	M_ASSERTPKTHDR(m);
243 	m_tag_delete_nonpersistent(m);
244 	m->m_pkthdr.rcvif = ifp;
245 
246 	/* BPF write needs to be handled specially */
247 	if (af == AF_UNSPEC) {
248 		KASSERT(m->m_len >= sizeof(int), ("if_simloop: m_len"));
249 		af = *(mtod(m, int *));
250 		m->m_len -= sizeof(int);
251 		m->m_pkthdr.len -= sizeof(int);
252 		m->m_data += sizeof(int);
253 	}
254 
255 	/* Let BPF see incoming packet */
256 	if (ifp->if_bpf) {
257 		if (ifp->if_bpf->bif_dlt == DLT_NULL) {
258 			u_int32_t af1 = af;	/* XXX beware sizeof(af) != 4 */
259 			/*
260 			 * We need to prepend the address family.
261 			 */
262 			bpf_mtap2(ifp->if_bpf, &af1, sizeof(af1), m);
263 		} else
264 			bpf_mtap(ifp->if_bpf, m);
265 	}
266 
267 	/* Strip away media header */
268 	if (hlen > 0) {
269 		m_adj(m, hlen);
270 #if defined(__alpha__) || defined(__ia64__) || defined(__sparc64__)
271 		/* The alpha doesn't like unaligned data.
272 		 * We move data down in the first mbuf */
273 		if (mtod(m, vm_offset_t) & 3) {
274 			KASSERT(hlen >= 3, ("if_simloop: hlen too small"));
275 			bcopy(m->m_data,
276 			    (char *)(mtod(m, vm_offset_t)
277 				- (mtod(m, vm_offset_t) & 3)),
278 			    m->m_len);
279 			m->m_data -= (mtod(m,vm_offset_t) & 3);
280 		}
281 #endif
282 	}
283 
284 	/* Deliver to upper layer protocol */
285 	switch (af) {
286 #ifdef INET
287 	case AF_INET:
288 		isr = NETISR_IP;
289 		break;
290 #endif
291 #ifdef INET6
292 	case AF_INET6:
293 		m->m_flags |= M_LOOP;
294 		isr = NETISR_IPV6;
295 		break;
296 #endif
297 #ifdef IPX
298 	case AF_IPX:
299 		isr = NETISR_IPX;
300 		break;
301 #endif
302 #ifdef NETATALK
303 	case AF_APPLETALK:
304 		isr = NETISR_ATALK2;
305 		break;
306 #endif
307 	default:
308 		printf("if_simloop: can't handle af=%d\n", af);
309 		m_freem(m);
310 		return (EAFNOSUPPORT);
311 	}
312 	ifp->if_ipackets++;
313 	ifp->if_ibytes += m->m_pkthdr.len;
314 	netisr_queue(isr, m);	/* mbuf is free'd on failure. */
315 	return (0);
316 }
317 
318 /* ARGSUSED */
319 static void
320 lortrequest(cmd, rt, info)
321 	int cmd;
322 	struct rtentry *rt;
323 	struct rt_addrinfo *info;
324 {
325 	RT_LOCK_ASSERT(rt);
326 	if (rt)
327 		rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
328 }
329 
330 /*
331  * Process an ioctl request.
332  */
333 /* ARGSUSED */
334 int
335 loioctl(ifp, cmd, data)
336 	register struct ifnet *ifp;
337 	u_long cmd;
338 	caddr_t data;
339 {
340 	register struct ifaddr *ifa;
341 	register struct ifreq *ifr = (struct ifreq *)data;
342 	register int error = 0;
343 
344 	switch (cmd) {
345 
346 	case SIOCSIFADDR:
347 		ifp->if_flags |= IFF_UP | IFF_RUNNING;
348 		ifa = (struct ifaddr *)data;
349 		ifa->ifa_rtrequest = lortrequest;
350 		/*
351 		 * Everything else is done at a higher level.
352 		 */
353 		break;
354 
355 	case SIOCADDMULTI:
356 	case SIOCDELMULTI:
357 		if (ifr == 0) {
358 			error = EAFNOSUPPORT;		/* XXX */
359 			break;
360 		}
361 		switch (ifr->ifr_addr.sa_family) {
362 
363 #ifdef INET
364 		case AF_INET:
365 			break;
366 #endif
367 #ifdef INET6
368 		case AF_INET6:
369 			break;
370 #endif
371 
372 		default:
373 			error = EAFNOSUPPORT;
374 			break;
375 		}
376 		break;
377 
378 	case SIOCSIFMTU:
379 		ifp->if_mtu = ifr->ifr_mtu;
380 		break;
381 
382 	case SIOCSIFFLAGS:
383 		break;
384 
385 	default:
386 		error = EINVAL;
387 	}
388 	return (error);
389 }
390