if_loop.c

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Author : dlg
Date : 2020-07-22 02:16:01
Hash : 23293512
Message : deprecate interface input handler lists, just use one input function. the interface input handler lists were originally set up to help us during the intial mpsafe network stack work. at the time not all the virtual ethernet interfaces (vlan, svlan, bridge, trunk, etc) were mpsafe, so we wanted a way to avoid them by default, and only take the kernel lock hit when they were specifically enabled on the interface. since then, they have been fixed up to be mpsafe. i could leave the list in place, but it has some semantic problems. because virtual interfaces filter packets based on the order they were attached to the parent interface, you can get packets taken away in surprising ways, especially when you reboot and netstart does something different to what you did by hand. by hardcoding the order that things like vlan and bridge get to look at packets, we can document the behaviour and get consistency. it also means we can get rid of a use of SRPs which were difficult to replace with SMRs. the interface input handler list is an SRPL, which we would like to deprecate. it turns out that you can sleep during stack processing, which you're not supposed to do with SRPs or SMRs, but SRPs are a lot more forgiving and it worked. lastly, it turns out that this code is faster than the input list handling, so lots of winning all around. special thanks to hrvoje popovski and aaron bieber for testing. this has been in snaps as part of a larger diff for over a week.

sys/net/if_loop.c

/*	$OpenBSD: if_loop.c,v 1.91 2020/07/22 02:16:01 dlg Exp $	*/
/*	$NetBSD: if_loop.c,v 1.15 1996/05/07 02:40:33 thorpej Exp $	*/

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 1982, 1986, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)if_loop.c	8.1 (Berkeley) 6/10/93
 */

/*
 *	@(#)COPYRIGHT	1.1 (NRL) 17 January 1995
 *
 * NRL grants permission for redistribution and use in source and binary
 * forms, with or without modification, of the software and documentation
 * created at NRL provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgements:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 *	This product includes software developed at the Information
 *	Technology Division, US Naval Research Laboratory.
 * 4. Neither the name of the NRL nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS
 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL NRL OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * The views and conclusions contained in the software and documentation
 * are those of the authors and should not be interpreted as representing
 * official policies, either expressed or implied, of the US Naval
 * Research Laboratory (NRL).
 */

/*
 * Loopback interface driver for protocol testing and timing.
 */

#include "bpfilter.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/ioctl.h>
#include <sys/time.h>


#include <net/if.h>
#include <net/if_var.h>
#include <net/if_types.h>
#include <net/netisr.h>
#include <net/rtable.h>
#include <net/route.h>

#include <netinet/in.h>

#ifdef INET6
#include <netinet/ip6.h>
#endif

#ifdef MPLS
#include <netmpls/mpls.h>
#endif

#if NBPFILTER > 0
#include <net/bpf.h>
#endif

#define	LOMTU	32768

int	loioctl(struct ifnet *, u_long, caddr_t);
void	loopattach(int);
void	lortrequest(struct ifnet *, int, struct rtentry *);
void	loinput(struct ifnet *, struct mbuf *);
int	looutput(struct ifnet *,
	    struct mbuf *, struct sockaddr *, struct rtentry *);

int	loop_clone_create(struct if_clone *, int);
int	loop_clone_destroy(struct ifnet *);

struct if_clone loop_cloner =
    IF_CLONE_INITIALIZER("lo", loop_clone_create, loop_clone_destroy);

void
loopattach(int n)
{
	if (loop_clone_create(&loop_cloner, 0))
		panic("unable to create lo0");

	if_clone_attach(&loop_cloner);
}

int
loop_clone_create(struct if_clone *ifc, int unit)
{
	struct ifnet *ifp;

	ifp = malloc(sizeof(*ifp), M_DEVBUF, M_WAITOK|M_ZERO);
	snprintf(ifp->if_xname, sizeof ifp->if_xname, "lo%d", unit);
	ifp->if_softc = NULL;
	ifp->if_mtu = LOMTU;
	ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
	ifp->if_xflags = IFXF_CLONED;
	ifp->if_rtrequest = lortrequest;
	ifp->if_ioctl = loioctl;
	ifp->if_input = loinput;
	ifp->if_output = looutput;
	ifp->if_type = IFT_LOOP;
	ifp->if_hdrlen = sizeof(u_int32_t);
	if (unit == 0) {
		if_attachhead(ifp);
		if_addgroup(ifp, ifc->ifc_name);
		rtable_l2set(0, 0, ifp->if_index);
	} else
		if_attach(ifp);
	if_alloc_sadl(ifp);
#if NBPFILTER > 0
	bpfattach(&ifp->if_bpf, ifp, DLT_LOOP, sizeof(u_int32_t));
#endif
	return (0);
}

int
loop_clone_destroy(struct ifnet *ifp)
{
	struct ifnet	*p;
	unsigned int	 rdomain = 0;

	if (ifp->if_index == rtable_loindex(ifp->if_rdomain)) {
		/* rdomain 0 always needs a loopback */
		if (ifp->if_rdomain == 0)
			return (EPERM);

		/* if there is any other interface in this rdomain, deny */
		NET_LOCK();
		TAILQ_FOREACH(p, &ifnet, if_list) {
			if (p->if_rdomain != ifp->if_rdomain)
				continue;
			if (p->if_index == ifp->if_index)
				continue;
			NET_UNLOCK();
			return (EBUSY);
		}
		NET_UNLOCK();

		rdomain = ifp->if_rdomain;
	}

	if_detach(ifp);

	free(ifp, M_DEVBUF, sizeof(*ifp));

	if (rdomain)
		rtable_l2set(rdomain, 0, 0);
	return (0);
}

void
loinput(struct ifnet *ifp, struct mbuf *m)
{
	int error;

	if ((m->m_flags & M_PKTHDR) == 0)
		panic("%s: no header mbuf", __func__);

	error = if_input_local(ifp, m, m->m_pkthdr.ph_family);
	if (error)
		ifp->if_ierrors++;
}

int
looutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
    struct rtentry *rt)
{
	if ((m->m_flags & M_PKTHDR) == 0)
		panic("%s: no header mbuf", __func__);

	if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
		m_freem(m);
		return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
			rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
	}

	/*
	 * Do not call if_input_local() directly.  Queue the packet to avoid
	 * stack overflow and make TCP handshake over loopback work.
	 */
	return (if_output_local(ifp, m, dst->sa_family));
}

void
lortrequest(struct ifnet *ifp, int cmd, struct rtentry *rt)
{
	if (rt && rt->rt_mtu == 0)
		rt->rt_mtu = LOMTU;
}

/*
 * Process an ioctl request.
 */
int
loioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
{
	struct ifreq *ifr;
	int error = 0;

	switch (cmd) {
	case SIOCSIFFLAGS:
		break;

	case SIOCSIFADDR:
		ifp->if_flags |= IFF_RUNNING;
		if_up(ifp);		/* send up RTM_IFINFO */
		/*
		 * Everything else is done at a higher level.
		 */
		break;

	case SIOCADDMULTI:
	case SIOCDELMULTI:
		break;

	case SIOCSIFMTU:
		ifr = (struct ifreq *)data;
		ifp->if_mtu = ifr->ifr_mtu;
		break;

	default:
		error = ENOTTY;
	}
	return (error);
}

IABSD.fr/src/sys/net/if_loop.c

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IABSD.fr/src /sys/net/if_loop.c