if_loop.c revision 331722 
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: stable/11/sys/net/if_loop.c 331722 2018-03-29 02:50:57Z eadler $
31 */
32
33/*
34 * Loopback interface driver for protocol testing and timing.
35 */
36
37#include "opt_inet.h"
38#include "opt_inet6.h"
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/kernel.h>
43#include <sys/mbuf.h>
44#include <sys/module.h>
45#include <machine/bus.h>
46#include <sys/rman.h>
47#include <sys/socket.h>
48#include <sys/sockio.h>
49#include <sys/sysctl.h>
50
51#include <net/if.h>
52#include <net/if_var.h>
53#include <net/if_clone.h>
54#include <net/if_types.h>
55#include <net/netisr.h>
56#include <net/route.h>
57#include <net/bpf.h>
58#include <net/vnet.h>
59
60#ifdef	INET
61#include <netinet/in.h>
62#include <netinet/in_var.h>
63#endif
64
65#ifdef INET6
66#ifndef INET
67#include <netinet/in.h>
68#endif
69#include <netinet6/in6_var.h>
70#include <netinet/ip6.h>
71#endif
72
73#include <security/mac/mac_framework.h>
74
75#ifdef TINY_LOMTU
76#define	LOMTU	(1024+512)
77#elif defined(LARGE_LOMTU)
78#define LOMTU	131072
79#else
80#define LOMTU	16384
81#endif
82
83#define	LO_CSUM_FEATURES	(CSUM_IP | CSUM_TCP | CSUM_UDP | CSUM_SCTP)
84#define	LO_CSUM_FEATURES6	(CSUM_TCP_IPV6 | CSUM_UDP_IPV6 | CSUM_SCTP_IPV6)
85#define	LO_CSUM_SET		(CSUM_DATA_VALID | CSUM_DATA_VALID_IPV6 | \
86				    CSUM_PSEUDO_HDR | \
87				    CSUM_IP_CHECKED | CSUM_IP_VALID | \
88				    CSUM_SCTP_VALID)
89
90int		loioctl(struct ifnet *, u_long, caddr_t);
91int		looutput(struct ifnet *ifp, struct mbuf *m,
92		    const struct sockaddr *dst, struct route *ro);
93static int	lo_clone_create(struct if_clone *, int, caddr_t);
94static void	lo_clone_destroy(struct ifnet *);
95
96VNET_DEFINE(struct ifnet *, loif);	/* Used externally */
97
98#ifdef VIMAGE
99static VNET_DEFINE(struct if_clone *, lo_cloner);
100#define	V_lo_cloner		VNET(lo_cloner)
101#endif
102
103static struct if_clone *lo_cloner;
104static const char loname[] = "lo";
105
106static void
107lo_clone_destroy(struct ifnet *ifp)
108{
109
110#ifndef VIMAGE
111	/* XXX: destroying lo0 will lead to panics. */
112	KASSERT(V_loif != ifp, ("%s: destroying lo0", __func__));
113#endif
114
115	bpfdetach(ifp);
116	if_detach(ifp);
117	if_free(ifp);
118}
119
120static int
121lo_clone_create(struct if_clone *ifc, int unit, caddr_t params)
122{
123	struct ifnet *ifp;
124
125	ifp = if_alloc(IFT_LOOP);
126	if (ifp == NULL)
127		return (ENOSPC);
128
129	if_initname(ifp, loname, unit);
130	ifp->if_mtu = LOMTU;
131	ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
132	ifp->if_ioctl = loioctl;
133	ifp->if_output = looutput;
134	ifp->if_snd.ifq_maxlen = ifqmaxlen;
135	ifp->if_capabilities = ifp->if_capenable =
136	    IFCAP_HWCSUM | IFCAP_HWCSUM_IPV6;
137	ifp->if_hwassist = LO_CSUM_FEATURES | LO_CSUM_FEATURES6;
138	if_attach(ifp);
139	bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
140	if (V_loif == NULL)
141		V_loif = ifp;
142
143	return (0);
144}
145
146static void
147vnet_loif_init(const void *unused __unused)
148{
149
150#ifdef VIMAGE
151	lo_cloner = if_clone_simple(loname, lo_clone_create, lo_clone_destroy,
152	    1);
153	V_lo_cloner = lo_cloner;
154#else
155	lo_cloner = if_clone_simple(loname, lo_clone_create, lo_clone_destroy,
156	    1);
157#endif
158}
159VNET_SYSINIT(vnet_loif_init, SI_SUB_PSEUDO, SI_ORDER_ANY,
160    vnet_loif_init, NULL);
161
162#ifdef VIMAGE
163static void
164vnet_loif_uninit(const void *unused __unused)
165{
166
167	if_clone_detach(V_lo_cloner);
168	V_loif = NULL;
169}
170VNET_SYSUNINIT(vnet_loif_uninit, SI_SUB_INIT_IF, SI_ORDER_SECOND,
171    vnet_loif_uninit, NULL);
172#endif
173
174static int
175loop_modevent(module_t mod, int type, void *data)
176{
177
178	switch (type) {
179	case MOD_LOAD:
180		break;
181
182	case MOD_UNLOAD:
183		printf("loop module unload - not possible for this module type\n");
184		return (EINVAL);
185
186	default:
187		return (EOPNOTSUPP);
188	}
189	return (0);
190}
191
192static moduledata_t loop_mod = {
193	"if_lo",
194	loop_modevent,
195	0
196};
197
198DECLARE_MODULE(if_lo, loop_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
199
200int
201looutput(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
202    struct route *ro)
203{
204	u_int32_t af;
205#ifdef MAC
206	int error;
207#endif
208
209	M_ASSERTPKTHDR(m); /* check if we have the packet header */
210
211#ifdef MAC
212	error = mac_ifnet_check_transmit(ifp, m);
213	if (error) {
214		m_freem(m);
215		return (error);
216	}
217#endif
218
219	if (ro != NULL && ro->ro_flags & (RT_REJECT|RT_BLACKHOLE)) {
220		m_freem(m);
221		return (ro->ro_flags & RT_BLACKHOLE ? 0 : EHOSTUNREACH);
222	}
223
224	if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
225	if_inc_counter(ifp, IFCOUNTER_OBYTES, m->m_pkthdr.len);
226
227	/* BPF writes need to be handled specially. */
228	if (dst->sa_family == AF_UNSPEC || dst->sa_family == pseudo_AF_HDRCMPLT)
229		bcopy(dst->sa_data, &af, sizeof(af));
230	else
231		af = dst->sa_family;
232
233#if 1	/* XXX */
234	switch (af) {
235	case AF_INET:
236		if (ifp->if_capenable & IFCAP_RXCSUM) {
237			m->m_pkthdr.csum_data = 0xffff;
238			m->m_pkthdr.csum_flags = LO_CSUM_SET;
239		}
240		m->m_pkthdr.csum_flags &= ~LO_CSUM_FEATURES;
241		break;
242	case AF_INET6:
243#if 0
244		/*
245		 * XXX-BZ for now always claim the checksum is good despite
246		 * any interface flags.   This is a workaround for 9.1-R and
247		 * a proper solution ought to be sought later.
248		 */
249		if (ifp->if_capenable & IFCAP_RXCSUM_IPV6) {
250			m->m_pkthdr.csum_data = 0xffff;
251			m->m_pkthdr.csum_flags = LO_CSUM_SET;
252		}
253#else
254		m->m_pkthdr.csum_data = 0xffff;
255		m->m_pkthdr.csum_flags = LO_CSUM_SET;
256#endif
257		m->m_pkthdr.csum_flags &= ~LO_CSUM_FEATURES6;
258		break;
259	default:
260		printf("looutput: af=%d unexpected\n", af);
261		m_freem(m);
262		return (EAFNOSUPPORT);
263	}
264#endif
265	return (if_simloop(ifp, m, af, 0));
266}
267
268/*
269 * if_simloop()
270 *
271 * This function is to support software emulation of hardware loopback,
272 * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
273 * hear their own broadcasts, we create a copy of the packet that we
274 * would normally receive via a hardware loopback.
275 *
276 * This function expects the packet to include the media header of length hlen.
277 */
278int
279if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen)
280{
281	int isr;
282
283	M_ASSERTPKTHDR(m);
284	m_tag_delete_nonpersistent(m);
285	m->m_pkthdr.rcvif = ifp;
286
287#ifdef MAC
288	mac_ifnet_create_mbuf(ifp, m);
289#endif
290
291	/*
292	 * Let BPF see incoming packet in the following manner:
293	 *  - Emulated packet loopback for a simplex interface
294	 *    (net/if_ethersubr.c)
295	 *	-> passes it to ifp's BPF
296	 *  - IPv4/v6 multicast packet loopback (netinet(6)/ip(6)_output.c)
297	 *	-> not passes it to any BPF
298	 *  - Normal packet loopback from myself to myself (net/if_loop.c)
299	 *	-> passes to lo0's BPF (even in case of IPv6, where ifp!=lo0)
300	 */
301	if (hlen > 0) {
302		if (bpf_peers_present(ifp->if_bpf)) {
303			bpf_mtap(ifp->if_bpf, m);
304		}
305	} else {
306		if (bpf_peers_present(V_loif->if_bpf)) {
307			if ((m->m_flags & M_MCAST) == 0 || V_loif == ifp) {
308				/* XXX beware sizeof(af) != 4 */
309				u_int32_t af1 = af;
310
311				/*
312				 * We need to prepend the address family.
313				 */
314				bpf_mtap2(V_loif->if_bpf, &af1, sizeof(af1), m);
315			}
316		}
317	}
318
319	/* Strip away media header */
320	if (hlen > 0) {
321		m_adj(m, hlen);
322#ifndef __NO_STRICT_ALIGNMENT
323		/*
324		 * Some archs do not like unaligned data, so
325		 * we move data down in the first mbuf.
326		 */
327		if (mtod(m, vm_offset_t) & 3) {
328			KASSERT(hlen >= 3, ("if_simloop: hlen too small"));
329			bcopy(m->m_data,
330			    (char *)(mtod(m, vm_offset_t)
331				- (mtod(m, vm_offset_t) & 3)),
332			    m->m_len);
333			m->m_data -= (mtod(m,vm_offset_t) & 3);
334		}
335#endif
336	}
337
338	/* Deliver to upper layer protocol */
339	switch (af) {
340#ifdef INET
341	case AF_INET:
342		isr = NETISR_IP;
343		break;
344#endif
345#ifdef INET6
346	case AF_INET6:
347		m->m_flags |= M_LOOP;
348		isr = NETISR_IPV6;
349		break;
350#endif
351	default:
352		printf("if_simloop: can't handle af=%d\n", af);
353		m_freem(m);
354		return (EAFNOSUPPORT);
355	}
356	if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
357	if_inc_counter(ifp, IFCOUNTER_IBYTES, m->m_pkthdr.len);
358	netisr_queue(isr, m);	/* mbuf is free'd on failure. */
359	return (0);
360}
361
362/*
363 * Process an ioctl request.
364 */
365/* ARGSUSED */
366int
367loioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
368{
369	struct ifreq *ifr = (struct ifreq *)data;
370	int error = 0, mask;
371
372	switch (cmd) {
373	case SIOCSIFADDR:
374		ifp->if_flags |= IFF_UP;
375		ifp->if_drv_flags |= IFF_DRV_RUNNING;
376		/*
377		 * Everything else is done at a higher level.
378		 */
379		break;
380
381	case SIOCADDMULTI:
382	case SIOCDELMULTI:
383		if (ifr == NULL) {
384			error = EAFNOSUPPORT;		/* XXX */
385			break;
386		}
387		switch (ifr->ifr_addr.sa_family) {
388
389#ifdef INET
390		case AF_INET:
391			break;
392#endif
393#ifdef INET6
394		case AF_INET6:
395			break;
396#endif
397
398		default:
399			error = EAFNOSUPPORT;
400			break;
401		}
402		break;
403
404	case SIOCSIFMTU:
405		ifp->if_mtu = ifr->ifr_mtu;
406		break;
407
408	case SIOCSIFFLAGS:
409		break;
410
411	case SIOCSIFCAP:
412		mask = ifp->if_capenable ^ ifr->ifr_reqcap;
413		if ((mask & IFCAP_RXCSUM) != 0)
414			ifp->if_capenable ^= IFCAP_RXCSUM;
415		if ((mask & IFCAP_TXCSUM) != 0)
416			ifp->if_capenable ^= IFCAP_TXCSUM;
417		if ((mask & IFCAP_RXCSUM_IPV6) != 0) {
418#if 0
419			ifp->if_capenable ^= IFCAP_RXCSUM_IPV6;
420#else
421			error = EOPNOTSUPP;
422			break;
423#endif
424		}
425		if ((mask & IFCAP_TXCSUM_IPV6) != 0) {
426#if 0
427			ifp->if_capenable ^= IFCAP_TXCSUM_IPV6;
428#else
429			error = EOPNOTSUPP;
430			break;
431#endif
432		}
433		ifp->if_hwassist = 0;
434		if (ifp->if_capenable & IFCAP_TXCSUM)
435			ifp->if_hwassist = LO_CSUM_FEATURES;
436#if 0
437		if (ifp->if_capenable & IFCAP_TXCSUM_IPV6)
438			ifp->if_hwassist |= LO_CSUM_FEATURES6;
439#endif
440		break;
441
442	default:
443		error = EINVAL;
444	}
445	return (error);
446}
447