if_tun.c

/* $FreeBSD: src/sys/net/if_tun.c,v 1.51.2.3 2000/05/03 22:48:37 archie Exp $ */
/*	$NetBSD: if_tun.c,v 1.14 1994/06/29 06:36:25 cgd Exp $	*/

/*
 * Copyright (c) 1988, Julian Onions <jpo@cs.nott.ac.uk>
 * Nottingham University 1987.
 *
 * This source may be freely distributed, however I would be interested
 * in any changes that are made.
 *
 * This driver takes packets off the IP i/f and hands them up to a
 * user process to have its wicked way with. This driver has it's
 * roots in a similar driver written by Phil Cockcroft (formerly) at
 * UCL. This driver is based much more on read/write/poll mode of
 * operation though.
 */

#include "tun.h"
#if NTUN > 0

#include "opt_devfs.h"
#include "opt_inet.h"
#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/filio.h>
#include <sys/sockio.h>
#include <sys/ttycom.h>
#include <sys/poll.h>
#include <sys/signalvar.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#ifdef DEVFS
#include <sys/devfsext.h>
#endif /*DEVFS*/
#include <sys/conf.h>
#include <sys/uio.h>
#include <sys/vnode.h>

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

#ifdef INET
#include <netinet/in.h>
#include <netinet/in_var.h>
#endif

#include <netinet/in_var.h>
#ifdef INET6
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_ifattach.h>
#endif /* INET6 */

#ifdef NS
#include <netns/ns.h>
#include <netns/ns_if.h>
#endif

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

#include <net/if_tunvar.h>
#include <net/if_tun.h>

static void tunattach __P((void *));
PSEUDO_SET(tunattach, if_tun);

#define TUNDEBUG	if (tundebug) printf
static int tundebug = 0;
SYSCTL_INT(_debug, OID_AUTO, if_tun_debug, CTLFLAG_RW, &tundebug, 0, "");

static struct tun_softc tunctl[NTUN];

static int tunoutput __P((struct ifnet *, struct mbuf *, struct sockaddr *,
	    struct rtentry *rt));
static int tunifioctl __P((struct ifnet *, u_long, caddr_t));
static int tuninit __P((int, int, u_char));
#ifdef ALTQ
static void tunstart __P((struct ifnet *));
#endif

static	d_open_t	tunopen;
static	d_close_t	tunclose;
static	d_read_t	tunread;
static	d_write_t	tunwrite;
static	d_ioctl_t	tunioctl;
static	d_poll_t	tunpoll;

#define CDEV_MAJOR 52
static struct cdevsw tun_cdevsw = {
	tunopen,	tunclose,	tunread,	tunwrite,
	tunioctl,	nullstop,	noreset,	nodevtotty,
	tunpoll,	nommap,		nostrategy,	"tun",	NULL,	-1
};


static	int	tun_devsw_installed;
#ifdef	DEVFS
static	void	*tun_devfs_token[NTUN];
#endif

#define minor_val(n) ((((n) & ~0xff) << 8) | ((n) & 0xff))
#define dev_val(n) (((n) >> 8) | ((n) & 0xff))

static void
tunattach(dummy)
	void *dummy;
{
	register int i;
	struct ifnet *ifp;
	dev_t dev;

	if ( tun_devsw_installed )
		return;
	dev = makedev(CDEV_MAJOR, 0);
	cdevsw_add(&dev, &tun_cdevsw, NULL);
	tun_devsw_installed = 1;
	for ( i = 0; i < NTUN; i++ ) {
#ifdef DEVFS
		tun_devfs_token[i] = devfs_add_devswf(&tun_cdevsw, minor_val(i),
						      DV_CHR, UID_UUCP,
						      GID_DIALER, 0600,
						      "tun%d", i);
#endif
		tunctl[i].tun_flags = TUN_INITED;

		ifp = &tunctl[i].tun_if;
		ifp->if_unit = i;
		ifp->if_name = "tun";
		ifp->if_mtu = TUNMTU;
		ifp->if_ioctl = tunifioctl;
		ifp->if_output = tunoutput;
#ifdef ALTQ
		ifp->if_start = tunstart;
#endif
		ifp->if_flags = IFF_POINTOPOINT | IFF_MULTICAST;
		ifp->if_type = IFT_PPP; /* necessary init value for IPv6 lladdr auto conf */
		IFQ_SET_MAXLEN(&ifp->if_snd, ifqmaxlen);
		IFQ_SET_READY(&ifp->if_snd);
		if_attach(ifp);
#if NBPFILTER > 0
		bpfattach(ifp, DLT_NULL, sizeof(u_int));
#endif
	}
}

/*
 * tunnel open - must be superuser & the device must be
 * configured in
 */
static	int
tunopen(dev, flag, mode, p)
	dev_t	dev;
	int	flag, mode;
	struct proc *p;
{
	struct ifnet	*ifp;
	struct tun_softc *tp;
	register int	unit, error;

	error = suser(p->p_ucred, &p->p_acflag);
	if (error)
		return (error);

	if ((unit = dev_val(minor(dev))) >= NTUN)
		return (ENXIO);
	tp = &tunctl[unit];
	if (tp->tun_flags & TUN_OPEN)
		return EBUSY;
	ifp = &tp->tun_if;
	tp->tun_flags |= TUN_OPEN;
	TUNDEBUG("%s%d: open\n", ifp->if_name, ifp->if_unit);
	return (0);
}

/*
 * tunclose - close the device - mark i/f down & delete
 * routing info
 */
static	int
tunclose(dev, foo, bar, p)
	dev_t dev;
	int foo;
	int bar;
	struct proc *p;
{
	register int	unit = dev_val(minor(dev)), s;
	struct tun_softc *tp = &tunctl[unit];
	struct ifnet	*ifp = &tp->tun_if;

	tp->tun_flags &= ~TUN_OPEN;

	/*
	 * junk all pending output
	 */
	s = splimp();
	IFQ_PURGE(&ifp->if_snd);
	splx(s);

	if (ifp->if_flags & IFF_UP) {
		s = splimp();
		if_down(ifp);
		if (ifp->if_flags & IFF_RUNNING) {
		    /* find internet addresses and delete routes */
		    register struct ifaddr *ifa;
		    for (ifa = ifp->if_addrhead.tqh_first; ifa;
			 ifa = ifa->ifa_link.tqe_next) {
			switch (ifa->ifa_addr->sa_family) {
#ifdef INET
			case AF_INET:
#endif
#ifdef INET6
			case AF_INET6:
#endif
			    rtinit(ifa, (int)RTM_DELETE,
				   tp->tun_flags & TUN_DSTADDR ? RTF_HOST : 0);
			    break;
			}
		    }
		}
		splx(s);
	}
	ifp->if_flags &= ~IFF_RUNNING;
	funsetown(tp->tun_sigio);
	selwakeup(&tp->tun_rsel);

	TUNDEBUG ("%s%d: closed\n", ifp->if_name, ifp->if_unit);
	return (0);
}

static int
tuninit(unit, cmd, af)
	int	unit;
	int	cmd;
	u_char	af;
{
	struct tun_softc *tp = &tunctl[unit];
	struct ifnet	*ifp = &tp->tun_if;
	register struct ifaddr *ifa;

	TUNDEBUG("%s%d: tuninit\n", ifp->if_name, ifp->if_unit);

	ifp->if_flags |= IFF_UP | IFF_RUNNING;
	getmicrotime(&ifp->if_lastchange);

	for (ifa = ifp->if_addrhead.tqh_first; ifa; 
	     ifa = ifa->ifa_link.tqe_next) {
#ifdef INET
		if (ifa->ifa_addr->sa_family == AF_INET) {
		    struct sockaddr_in *si;

		    si = (struct sockaddr_in *)ifa->ifa_addr;
		    if (si && si->sin_addr.s_addr)
			    tp->tun_flags |= TUN_IASET;

		    si = (struct sockaddr_in *)ifa->ifa_dstaddr;
		    if (si && si->sin_addr.s_addr)
			    tp->tun_flags |= TUN_DSTADDR;
		}
#endif
	}
	return 0;
}

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

	s = splimp();
	switch(cmd) {
	case SIOCSIFADDR:
	case SIOCSIFDSTADDR:
		tuninit(ifp->if_unit, cmd, ifr->ifr_addr.sa_family);
		break;
	case SIOCSIFMTU:
		ifp->if_mtu = ifr->ifr_mtu;
		TUNDEBUG("%s%d: mtu set\n",
			 ifp->if_name, ifp->if_unit);
		break;
	case SIOCADDMULTI:
	case SIOCDELMULTI:
		break;

	case SIOCSIFFLAGS:
		if ((ifp->if_flags & IFF_UP) != 0)
			ifp->if_flags |= IFF_RUNNING;
		else if ((ifp->if_flags & IFF_UP) == 0)
			ifp->if_flags &= ~IFF_RUNNING;
		break;

	default:
		error = EINVAL;
	}
	splx(s);
	return (error);
}

/*
 * tunoutput - queue packets from higher level ready to put out.
 */
/* Packet data format between tun and ppp is changed to enable checking of
 * Address Family of sending packet. When INET6 is defined, 4byte AF field
 * is appended to packet data as following.
 *
 *        0  1  2  3  4  5  6  7  8 .....
 *       ------------------------------
 *       |    af     |  packet data .....
 *       ------------------------------
 *       ^^^^^^^^^^^^^
 *       Newly added part. The size is sizeof(u_long).
 *
 * However, this is not adopted for tun -> ppp AF_INET packet for 
 * backword compatibility, because the ppp process may be an existing
 * ip only supporting one.  
 * Also in ppp->tun case, when af value is unknown, (af > 255) is checked and
 * if it is true, AF_INET is assumed. (the 4byte may be the head of
 * AF_INET packet. Despite the byte order, the value must always be
 * greater than 255, because of ip_len field or (ip_v and ip_hl)
 * field. (Idea from Mr. Noritoshi Demize)
 */
int
tunoutput(ifp, m0, dst, rt)
	struct ifnet   *ifp;
	struct mbuf    *m0;
	struct sockaddr *dst;
	struct rtentry *rt;
{
	struct tun_softc *tp = &tunctl[ifp->if_unit];
	int		s, error, len;
	ALTQ_DECL(struct altq_pktattr pktattr;)

	TUNDEBUG ("%s%d: tunoutput\n", ifp->if_name, ifp->if_unit);

	if ((tp->tun_flags & TUN_READY) != TUN_READY) {
		TUNDEBUG ("%s%d: not ready 0%o\n", ifp->if_name,
			  ifp->if_unit, tp->tun_flags);
		m_freem (m0);
		return EHOSTDOWN;
	}

	/*
	 * if the queueing discipline needs packet classification,
	 * do it before prepending link headers.
	 */
	IFQ_CLASSIFY(&ifp->if_snd, m0, dst->sa_family, &pktattr);

#if NBPFILTER > 0
	/* BPF write needs to be handled specially */
	if (dst->sa_family == AF_UNSPEC) {
		dst->sa_family = *(mtod(m0, int *));
		m0->m_len -= sizeof(int);
		m0->m_pkthdr.len -= sizeof(int);
		m0->m_data += sizeof(int);
	}

	if (ifp->if_bpf) {
		/*
		 * We need to prepend the address family as
		 * a four byte field.  Cons up a dummy header
		 * to pacify bpf.  This is safe because bpf
		 * will only read from the mbuf (i.e., it won't
		 * try to free it or keep a pointer to it).
		 */
		struct mbuf m;
		u_int af = dst->sa_family;

		m.m_next = m0;
		m.m_len = 4;
		m.m_data = (char *)&af;

		bpf_mtap(ifp, &m);
	}
#endif

	switch(dst->sa_family) {
#if defined(INET) || defined(INET6)
#ifdef INET6
	case AF_INET6:
		M_PREPEND(m0, sizeof(u_long) /* af field passed to upper */,
			  M_DONTWAIT);
		if (m0 == 0)
			return (ENOBUFS);
		*mtod(m0, u_long *) = (u_long)dst->sa_family;
		/* FALLTHROUGH */
#endif /* INET6 */
#ifdef INET
	case AF_INET:
#endif /* INET */
#endif /* INET || INET6 */
		len = m0->m_pkthdr.len;
		s = splimp();
		IFQ_ENQUEUE(&ifp->if_snd, m0, &pktattr, error);
		if (error) {
			splx(s);
			ifp->if_collisions++;
			return (error);
		}
		ifp->if_obytes += len;
		splx(s);
		ifp->if_opackets++;
		break;
	default:
		m_freem(m0);
		return EAFNOSUPPORT;
	}

	if (tp->tun_flags & TUN_RWAIT) {
		tp->tun_flags &= ~TUN_RWAIT;
		wakeup((caddr_t)tp);
	}
	if (tp->tun_flags & TUN_ASYNC && tp->tun_sigio)
		pgsigio(tp->tun_sigio, SIGIO, 0);
	selwakeup(&tp->tun_rsel);
	return 0;
}

/*
 * the cdevsw interface is now pretty minimal.
 */
static	int
tunioctl(dev, cmd, data, flag, p)
	dev_t		dev;
	u_long		cmd;
	caddr_t		data;
	int		flag;
	struct proc	*p;
{
	int		unit = dev_val(minor(dev)), s;
	struct tun_softc *tp = &tunctl[unit];
 	struct tuninfo *tunp;

	switch (cmd) {
 	case TUNSIFINFO:
 	        tunp = (struct tuninfo *)data;
		if (tunp->mtu < IF_MINMTU)
			return (EINVAL);
 		tp->tun_if.if_mtu = tunp->mtu;
 		tp->tun_if.if_type = tunp->type;
 		tp->tun_if.if_baudrate = tunp->baudrate;
 		break;
 	case TUNGIFINFO:
 		tunp = (struct tuninfo *)data;
 		tunp->mtu = tp->tun_if.if_mtu;
 		tunp->type = tp->tun_if.if_type;
 		tunp->baudrate = tp->tun_if.if_baudrate;
 		break;
	case TUNSDEBUG:
		tundebug = *(int *)data;
		break;
	case TUNGDEBUG:
		*(int *)data = tundebug;
		break;
	case FIONBIO:
		break;
	case FIOASYNC:
		if (*(int *)data)
			tp->tun_flags |= TUN_ASYNC;
		else
			tp->tun_flags &= ~TUN_ASYNC;
		break;
	case FIONREAD:
		s = splimp();
		if (!IFQ_IS_EMPTY(&tp->tun_if.if_snd)) {
			struct mbuf *mb;

			IFQ_POLL(&tp->tun_if.if_snd, mb);
			for( *(int *)data = 0; mb != 0; mb = mb->m_next) 
				*(int *)data += mb->m_len;
		} else
			*(int *)data = 0;
		splx(s);
		break;
	case FIOSETOWN:
		return (fsetown(*(int *)data, &tp->tun_sigio));

	case FIOGETOWN:
		*(int *)data = fgetown(tp->tun_sigio);
		return (0);

	/* This is deprecated, FIOSETOWN should be used instead. */
	case TIOCSPGRP:
		return (fsetown(-(*(int *)data), &tp->tun_sigio));

	/* This is deprecated, FIOGETOWN should be used instead. */
	case TIOCGPGRP:
		*(int *)data = -fgetown(tp->tun_sigio);
		return (0);

	default:
		return (ENOTTY);
	}
	return (0);
}

/*
 * The cdevsw read interface - reads a packet at a time, or at
 * least as much of a packet as can be read.
 */
static	int
tunread(dev, uio, flag)
	dev_t dev;
	struct uio *uio;
	int flag;
{
	int		unit = dev_val(minor(dev));
	struct tun_softc *tp = &tunctl[unit];
	struct ifnet	*ifp = &tp->tun_if;
	struct mbuf	*m, *m0;
	int		error=0, len, s;

	TUNDEBUG ("%s%d: read\n", ifp->if_name, ifp->if_unit);
	if ((tp->tun_flags & TUN_READY) != TUN_READY) {
		TUNDEBUG ("%s%d: not ready 0%o\n", ifp->if_name,
			  ifp->if_unit, tp->tun_flags);
		return EHOSTDOWN;
	}

	tp->tun_flags &= ~TUN_RWAIT;

	s = splimp();
	do {
		IFQ_DEQUEUE(&ifp->if_snd, m0);
		if (m0 == 0) {
			if (flag & IO_NDELAY) {
				splx(s);
				return EWOULDBLOCK;
			}
			tp->tun_flags |= TUN_RWAIT;
			if( error = tsleep((caddr_t)tp, PCATCH | (PZERO + 1),
					"tunread", 0)) {
				splx(s);
				return error;
			}
		}
	} while (m0 == 0);
	splx(s);

	while (m0 && uio->uio_resid > 0 && error == 0) {
		len = min(uio->uio_resid, m0->m_len);
		if (len != 0)
			error = uiomove(mtod(m0, caddr_t), len, uio);
		MFREE(m0, m);
		m0 = m;
	}

	if (m0) {
		TUNDEBUG("Dropping mbuf\n");
		m_freem(m0);
	}
	return error;
}

/*
 * the cdevsw write interface - an atomic write is a packet - or else!
 */
/* See top of tunoutput() about interface change between ppp process and 
 * tun. */
static	int
tunwrite(dev, uio, flag)
	dev_t dev;
	struct uio *uio;
	int flag;
{
	int		unit = dev_val(minor(dev));
	struct ifnet	*ifp = &tunctl[unit].tun_if;
	struct mbuf	*top, **mp, *m;
	int		error=0, s, tlen, mlen;
	u_long af;
	u_int netisr_af;
	struct ifqueue *afintrq = NULL;

	TUNDEBUG("%s%d: tunwrite\n", ifp->if_name, ifp->if_unit);

	if (uio->uio_resid == 0)
		return 0;

	if (uio->uio_resid < 0 || uio->uio_resid > TUNMRU) {
		TUNDEBUG("%s%d: len=%d!\n", ifp->if_name, ifp->if_unit,
		    uio->uio_resid);
		return EIO;
	}
	tlen = uio->uio_resid;

	/* get a header mbuf */
	MGETHDR(m, M_DONTWAIT, MT_DATA);
	if (m == NULL)
		return ENOBUFS;
	if (tlen > MHLEN) {
	  MCLGET(m, M_DONTWAIT);
	  if ((m->m_flags & M_EXT) == 0) {
	    m_free(m);
	    return ENOBUFS;
	  }
	  mlen = m->m_ext.ext_size;
	} else
	  mlen = MHLEN;

	top = 0;
	mp = &top;
	while (error == 0 && uio->uio_resid > 0) {
		m->m_len = min(mlen, uio->uio_resid);
		error = uiomove(mtod (m, caddr_t), m->m_len, uio);
		*mp = m;
		mp = &m->m_next;
		if (uio->uio_resid > 0) {
			MGET (m, M_DONTWAIT, MT_DATA);
			if (m == 0) {
				error = ENOBUFS;
				break;
			}
			mlen = MLEN;
		}
	}
	/* Change for checking Address Family of sending packet. */
	af = *mtod(top, u_long *);
	switch (af) {
#ifdef INET
	case AF_INET:
		netisr_af = NETISR_IP;
		afintrq = &ipintrq;
		break;
#endif /* INET */
#ifdef INET6
	case AF_INET6:
		netisr_af = NETISR_IPV6;
		afintrq = &ip6intrq;
		break;
#endif /* INET6 */
	default:
		if (af > 255) { /* see description at the top of tunoutput */
			af = AF_INET;
			netisr_af = NETISR_IP;
			afintrq = &ipintrq;
			goto af_decided;
		}
		error = EAFNOSUPPORT;
		break;
	}
	m_adj(top, sizeof(u_long)); /* remove af field passed from upper */
	tlen -= sizeof(u_long);
      af_decided:
	if (error) {
		if (top)
			m_freem (top);
		return error;
	}
	top->m_pkthdr.len = tlen;
	top->m_pkthdr.rcvif = ifp;

#if NBPFILTER > 0
	if (ifp->if_bpf) {
		/*
		 * We need to prepend the address family as
		 * a four byte field.  Cons up a dummy header
		 * to pacify bpf.  This is safe because bpf
		 * will only read from the mbuf (i.e., it won't
		 * try to free it or keep a pointer to it).
		 */
		struct mbuf m;

		m.m_next = top;
		m.m_len = 4;
		m.m_data = (char *)&af;

		bpf_mtap(ifp, &m);
	}
#endif

	/* just for safety */
	if (!afintrq)
		return EAFNOSUPPORT;

	s = splimp();
	if (IF_QFULL (afintrq)) {
		IF_DROP(afintrq);
		splx(s);
		ifp->if_collisions++;
		m_freem(top);
		return ENOBUFS;
	}
	IF_ENQUEUE(afintrq, top);
	splx(s);
	ifp->if_ibytes += tlen;
	ifp->if_ipackets++;
	schednetisr(netisr_af);
	return error;
}

/*
 * tunpoll - the poll interface, this is only useful on reads
 * really. The write detect always returns true, write never blocks
 * anyway, it either accepts the packet or drops it.
 */
static	int
tunpoll(dev, events, p)
	dev_t dev;
	int events;
	struct proc *p;
{
	int		unit = dev_val(minor(dev)), s;
	struct tun_softc *tp = &tunctl[unit];
	struct ifnet	*ifp = &tp->tun_if;
	int		revents = 0;

	s = splimp();
	TUNDEBUG("%s%d: tunpoll\n", ifp->if_name, ifp->if_unit);

	if (events & (POLLIN | POLLRDNORM))
		if (!IFQ_IS_EMPTY(&ifp->if_snd)) {
			TUNDEBUG("%s%d: tunpoll q=%d\n", ifp->if_name,
			    ifp->if_unit, ifp->if_snd.ifq_len);
			revents |= events & (POLLIN | POLLRDNORM);
		} else {
			TUNDEBUG("%s%d: tunpoll waiting\n", ifp->if_name,
			    ifp->if_unit);
			selrecord(p, &tp->tun_rsel);
		}

	if (events & (POLLOUT | POLLWRNORM))
		revents |= events & (POLLOUT | POLLWRNORM);

	splx(s);
	return (revents);
}

#ifdef ALTQ
/*
 * Start packet transmission on the interface.
 * when the interface queue is rate-limited by ALTQ or TBR,
 * if_start is needed to drain packets from the queue in order
 * to notify readers when outgoing packets become ready.
 */
static void
tunstart(ifp)
	struct ifnet *ifp;
{
	struct tun_softc *tp = ifp->if_softc;
	struct mbuf *m;

	if (!ALTQ_IS_ENABLED(&ifp->if_snd) && !TBR_IS_ENABLED(&ifp->if_snd))
		return;

	IFQ_POLL(&ifp->if_snd, m);
	if (m != NULL) {
		if (tp->tun_flags & TUN_RWAIT) {
			tp->tun_flags &= ~TUN_RWAIT;
			wakeup((caddr_t)tp);
		}
		if (tp->tun_flags & TUN_ASYNC && tp->tun_sigio)
			pgsigio(tp->tun_sigio, SIGIO, 0);
		selwakeup(&tp->tun_rsel);
	}
}
#endif

#endif  /* NTUN */