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freebsd-nq/sys/net/if_tun.c
Christian S.J. Peron 16d878cc99 Fix the following bpf(4) race condition which can result in a panic: 
(1) bpf peer attaches to interface netif0
	(2) Packet is received by netif0
	(3) ifp->if_bpf pointer is checked and handed off to bpf
	(4) bpf peer detaches from netif0 resulting in ifp->if_bpf being
	    initialized to NULL.
	(5) ifp->if_bpf is dereferenced by bpf machinery
	(6) Kaboom

This race condition likely explains the various different kernel panics
reported around sending SIGINT to tcpdump or dhclient processes. But really
this race can result in kernel panics anywhere you have frequent bpf attach
and detach operations with high packet per second load.

Summary of changes:

- Remove the bpf interface's "driverp" member
- When we attach bpf interfaces, we now set the ifp->if_bpf member to the
  bpf interface structure. Once this is done, ifp->if_bpf should never be
  NULL. [1]
- Introduce bpf_peers_present function, an inline operation which will do
  a lockless read bpf peer list associated with the interface. It should
  be noted that the bpf code will pickup the bpf_interface lock before adding
  or removing bpf peers. This should serialize the access to the bpf descriptor
  list, removing the race.
- Expose the bpf_if structure in bpf.h so that the bpf_peers_present function
  can use it. This also removes the struct bpf_if; hack that was there.
- Adjust all consumers of the raw if_bpf structure to use bpf_peers_present

Now what happens is:

	(1) Packet is received by netif0
	(2) Check to see if bpf descriptor list is empty
	(3) Pickup the bpf interface lock
	(4) Hand packet off to process

From the attach/detach side:

	(1) Pickup the bpf interface lock
	(2) Add/remove from bpf descriptor list

Now that we are storing the bpf interface structure with the ifnet, there is
is no need to walk the bpf interface list to locate the correct bpf interface.
We now simply look up the interface, and initialize the pointer. This has a
nice side effect of changing a bpf interface attach operation from O(N) (where
N is the number of bpf interfaces), to O(1).

[1] From now on, we can no longer check ifp->if_bpf to tell us whether or
    not we have any bpf peers that might be interested in receiving packets.

In collaboration with:	sam@
MFC after:	1 month
2006-06-02 19:59:33 +00:00

866 lines
19 KiB
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/* $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.
*
* $FreeBSD$
*/
#include "opt_atalk.h"
#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_ipx.h"
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/mac.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/socket.h>
#include <sys/fcntl.h>
#include <sys/filio.h>
#include <sys/sockio.h>
#include <sys/ttycom.h>
#include <sys/poll.h>
#include <sys/selinfo.h>
#include <sys/signalvar.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/conf.h>
#include <sys/uio.h>
#include <sys/malloc.h>
#include <sys/random.h>
#include <net/if.h>
#include <net/if_types.h>
#include <net/netisr.h>
#include <net/route.h>
#ifdef INET
#include <netinet/in.h>
#endif
#include <net/bpf.h>
#include <net/if_tun.h>
#include <sys/queue.h>
/*
* tun_list is protected by global tunmtx. Other mutable fields are
* protected by tun->tun_mtx, or by their owning subsystem. tun_dev is
* static for the duration of a tunnel interface.
*/
struct tun_softc {
TAILQ_ENTRY(tun_softc) tun_list;
struct cdev *tun_dev;
u_short tun_flags; /* misc flags */
#define TUN_OPEN 0x0001
#define TUN_INITED 0x0002
#define TUN_RCOLL 0x0004
#define TUN_IASET 0x0008
#define TUN_DSTADDR 0x0010
#define TUN_LMODE 0x0020
#define TUN_RWAIT 0x0040
#define TUN_ASYNC 0x0080
#define TUN_IFHEAD 0x0100
#define TUN_READY (TUN_OPEN | TUN_INITED)
/*
* XXXRW: tun_pid is used to exclusively lock /dev/tun. Is this
* actually needed? Can we just return EBUSY if already open?
* Problem is that this involved inherent races when a tun device
* is handed off from one process to another, as opposed to just
* being slightly stale informationally.
*/
pid_t tun_pid; /* owning pid */
struct ifnet *tun_ifp; /* the interface */
struct sigio *tun_sigio; /* information for async I/O */
struct selinfo tun_rsel; /* read select */
struct mtx tun_mtx; /* protect mutable softc fields */
};
#define TUN2IFP(sc) ((sc)->tun_ifp)
#define TUNDEBUG if (tundebug) if_printf
#define TUNNAME "tun"
/*
* All mutable global variables in if_tun are locked using tunmtx, with
* the exception of tundebug, which is used unlocked, and tunclones,
* which is static after setup.
*/
static struct mtx tunmtx;
static MALLOC_DEFINE(M_TUN, TUNNAME, "Tunnel Interface");
static int tundebug = 0;
static struct clonedevs *tunclones;
static TAILQ_HEAD(,tun_softc) tunhead = TAILQ_HEAD_INITIALIZER(tunhead);
SYSCTL_INT(_debug, OID_AUTO, if_tun_debug, CTLFLAG_RW, &tundebug, 0, "");
static void tunclone(void *arg, struct ucred *cred, char *name,
int namelen, struct cdev **dev);
static void tuncreate(struct cdev *dev);
static int tunifioctl(struct ifnet *, u_long, caddr_t);
static int tuninit(struct ifnet *);
static int tunmodevent(module_t, int, void *);
static int tunoutput(struct ifnet *, struct mbuf *, struct sockaddr *,
struct rtentry *rt);
static void tunstart(struct ifnet *);
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;
static struct cdevsw tun_cdevsw = {
.d_version = D_VERSION,
.d_flags = D_PSEUDO | D_NEEDGIANT,
.d_open = tunopen,
.d_close = tunclose,
.d_read = tunread,
.d_write = tunwrite,
.d_ioctl = tunioctl,
.d_poll = tunpoll,
.d_name = TUNNAME,
};
static void
tunclone(void *arg, struct ucred *cred, char *name, int namelen,
struct cdev **dev)
{
int u, i;
if (*dev != NULL)
return;
if (strcmp(name, TUNNAME) == 0) {
u = -1;
} else if (dev_stdclone(name, NULL, TUNNAME, &u) != 1)
return; /* Don't recognise the name */
if (u != -1 && u > IF_MAXUNIT)
return; /* Unit number too high */
/* find any existing device, or allocate new unit number */
i = clone_create(&tunclones, &tun_cdevsw, &u, dev, 0);
if (i) {
/* No preexisting struct cdev *, create one */
*dev = make_dev(&tun_cdevsw, unit2minor(u),
UID_UUCP, GID_DIALER, 0600, "tun%d", u);
if (*dev != NULL) {
dev_ref(*dev);
(*dev)->si_flags |= SI_CHEAPCLONE;
}
}
}
static void
tun_destroy(struct tun_softc *tp)
{
struct cdev *dev;
/* Unlocked read. */
KASSERT((tp->tun_flags & TUN_OPEN) == 0,
("tununits is out of sync - unit %d", TUN2IFP(tp)->if_dunit));
dev = tp->tun_dev;
bpfdetach(TUN2IFP(tp));
if_detach(TUN2IFP(tp));
if_free(TUN2IFP(tp));
destroy_dev(dev);
mtx_destroy(&tp->tun_mtx);
free(tp, M_TUN);
}
static int
tunmodevent(module_t mod, int type, void *data)
{
static eventhandler_tag tag;
struct tun_softc *tp;
switch (type) {
case MOD_LOAD:
mtx_init(&tunmtx, "tunmtx", NULL, MTX_DEF);
clone_setup(&tunclones);
tag = EVENTHANDLER_REGISTER(dev_clone, tunclone, 0, 1000);
if (tag == NULL)
return (ENOMEM);
break;
case MOD_UNLOAD:
EVENTHANDLER_DEREGISTER(dev_clone, tag);
mtx_lock(&tunmtx);
while ((tp = TAILQ_FIRST(&tunhead)) != NULL) {
TAILQ_REMOVE(&tunhead, tp, tun_list);
mtx_unlock(&tunmtx);
tun_destroy(tp);
mtx_lock(&tunmtx);
}
mtx_unlock(&tunmtx);
clone_cleanup(&tunclones);
mtx_destroy(&tunmtx);
break;
default:
return EOPNOTSUPP;
}
return 0;
}
static moduledata_t tun_mod = {
"if_tun",
tunmodevent,
0
};
DECLARE_MODULE(if_tun, tun_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
static void
tunstart(struct ifnet *ifp)
{
struct tun_softc *tp = ifp->if_softc;
struct mbuf *m;
if (ALTQ_IS_ENABLED(&ifp->if_snd)) {
IFQ_LOCK(&ifp->if_snd);
IFQ_POLL_NOLOCK(&ifp->if_snd, m);
if (m == NULL) {
IFQ_UNLOCK(&ifp->if_snd);
return;
}
IFQ_UNLOCK(&ifp->if_snd);
}
mtx_lock(&tp->tun_mtx);
if (tp->tun_flags & TUN_RWAIT) {
tp->tun_flags &= ~TUN_RWAIT;
wakeup(tp);
}
if (tp->tun_flags & TUN_ASYNC && tp->tun_sigio) {
mtx_unlock(&tp->tun_mtx);
pgsigio(&tp->tun_sigio, SIGIO, 0);
} else
mtx_unlock(&tp->tun_mtx);
selwakeuppri(&tp->tun_rsel, PZERO + 1);
}
/* XXX: should return an error code so it can fail. */
static void
tuncreate(struct cdev *dev)
{
struct tun_softc *sc;
struct ifnet *ifp;
dev->si_flags &= ~SI_CHEAPCLONE;
MALLOC(sc, struct tun_softc *, sizeof(*sc), M_TUN, M_WAITOK | M_ZERO);
mtx_init(&sc->tun_mtx, "tun_mtx", NULL, MTX_DEF);
sc->tun_flags = TUN_INITED;
sc->tun_dev = dev;
mtx_lock(&tunmtx);
TAILQ_INSERT_TAIL(&tunhead, sc, tun_list);
mtx_unlock(&tunmtx);
ifp = sc->tun_ifp = if_alloc(IFT_PPP);
if (ifp == NULL)
panic("%s%d: failed to if_alloc() interface.\n",
TUNNAME, dev2unit(dev));
if_initname(ifp, TUNNAME, dev2unit(dev));
ifp->if_mtu = TUNMTU;
ifp->if_ioctl = tunifioctl;
ifp->if_output = tunoutput;
ifp->if_start = tunstart;
ifp->if_flags = IFF_POINTOPOINT | IFF_MULTICAST;
ifp->if_softc = sc;
IFQ_SET_MAXLEN(&ifp->if_snd, ifqmaxlen);
ifp->if_snd.ifq_drv_maxlen = 0;
IFQ_SET_READY(&ifp->if_snd);
if_attach(ifp);
bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
dev->si_drv1 = sc;
}
static int
tunopen(struct cdev *dev, int flag, int mode, struct thread *td)
{
struct ifnet *ifp;
struct tun_softc *tp;
/*
* XXXRW: Non-atomic test and set of dev->si_drv1 requires
* synchronization.
*/
tp = dev->si_drv1;
if (!tp) {
tuncreate(dev);
tp = dev->si_drv1;
}
/*
* XXXRW: This use of tun_pid is subject to error due to the
* fact that a reference to the tunnel can live beyond the
* death of the process that created it. Can we replace this
* with a simple busy flag?
*/
mtx_lock(&tp->tun_mtx);
if (tp->tun_pid != 0 && tp->tun_pid != td->td_proc->p_pid) {
mtx_unlock(&tp->tun_mtx);
return (EBUSY);
}
tp->tun_pid = td->td_proc->p_pid;
tp->tun_flags |= TUN_OPEN;
mtx_unlock(&tp->tun_mtx);
ifp = TUN2IFP(tp);
TUNDEBUG(ifp, "open\n");
return (0);
}
/*
* tunclose - close the device - mark i/f down & delete
* routing info
*/
static int
tunclose(struct cdev *dev, int foo, int bar, struct thread *td)
{
struct tun_softc *tp;
struct ifnet *ifp;
int s;
tp = dev->si_drv1;
ifp = TUN2IFP(tp);
mtx_lock(&tp->tun_mtx);
tp->tun_flags &= ~TUN_OPEN;
tp->tun_pid = 0;
/*
* junk all pending output
*/
s = splimp();
IFQ_PURGE(&ifp->if_snd);
splx(s);
mtx_unlock(&tp->tun_mtx);
if (ifp->if_flags & IFF_UP) {
s = splimp();
if_down(ifp);
splx(s);
}
if (ifp->if_drv_flags & IFF_DRV_RUNNING) {
struct ifaddr *ifa;
s = splimp();
/* find internet addresses and delete routes */
TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
if (ifa->ifa_addr->sa_family == AF_INET)
/* Unlocked read. */
rtinit(ifa, (int)RTM_DELETE,
tp->tun_flags & TUN_DSTADDR ? RTF_HOST : 0);
ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
splx(s);
}
funsetown(&tp->tun_sigio);
selwakeuppri(&tp->tun_rsel, PZERO + 1);
TUNDEBUG (ifp, "closed\n");
return (0);
}
static int
tuninit(struct ifnet *ifp)
{
struct tun_softc *tp = ifp->if_softc;
struct ifaddr *ifa;
int error = 0;
TUNDEBUG(ifp, "tuninit\n");
ifp->if_flags |= IFF_UP;
ifp->if_drv_flags |= IFF_DRV_RUNNING;
getmicrotime(&ifp->if_lastchange);
for (ifa = TAILQ_FIRST(&ifp->if_addrhead); ifa;
ifa = TAILQ_NEXT(ifa, ifa_link)) {
if (ifa->ifa_addr == NULL)
error = EFAULT;
/* XXX: Should maybe return straight off? */
else {
#ifdef INET
if (ifa->ifa_addr->sa_family == AF_INET) {
struct sockaddr_in *si;
si = (struct sockaddr_in *)ifa->ifa_addr;
mtx_lock(&tp->tun_mtx);
if (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;
mtx_unlock(&tp->tun_mtx);
}
#endif
}
}
return (error);
}
/*
* Process an ioctl request.
*/
static int
tunifioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
{
struct ifreq *ifr = (struct ifreq *)data;
struct tun_softc *tp = ifp->if_softc;
struct ifstat *ifs;
int error = 0, s;
s = splimp();
switch(cmd) {
case SIOCGIFSTATUS:
ifs = (struct ifstat *)data;
mtx_lock(&tp->tun_mtx);
if (tp->tun_pid)
sprintf(ifs->ascii + strlen(ifs->ascii),
"\tOpened by PID %d\n", tp->tun_pid);
mtx_unlock(&tp->tun_mtx);
break;
case SIOCSIFADDR:
error = tuninit(ifp);
TUNDEBUG(ifp, "address set, error=%d\n", error);
break;
case SIOCSIFDSTADDR:
error = tuninit(ifp);
TUNDEBUG(ifp, "destination address set, error=%d\n", error);
break;
case SIOCSIFMTU:
ifp->if_mtu = ifr->ifr_mtu;
TUNDEBUG(ifp, "mtu set\n");
break;
case SIOCSIFFLAGS:
case SIOCADDMULTI:
case SIOCDELMULTI:
break;
default:
error = EINVAL;
}
splx(s);
return (error);
}
/*
* tunoutput - queue packets from higher level ready to put out.
*/
static int
tunoutput(
struct ifnet *ifp,
struct mbuf *m0,
struct sockaddr *dst,
struct rtentry *rt)
{
struct tun_softc *tp = ifp->if_softc;
u_short cached_tun_flags;
int error;
u_int32_t af;
TUNDEBUG (ifp, "tunoutput\n");
#ifdef MAC
error = mac_check_ifnet_transmit(ifp, m0);
if (error) {
m_freem(m0);
return (error);
}
#endif
/* Could be unlocked read? */
mtx_lock(&tp->tun_mtx);
cached_tun_flags = tp->tun_flags;
mtx_unlock(&tp->tun_mtx);
if ((cached_tun_flags & TUN_READY) != TUN_READY) {
TUNDEBUG (ifp, "not ready 0%o\n", tp->tun_flags);
m_freem (m0);
return (EHOSTDOWN);
}
if ((ifp->if_flags & IFF_UP) != IFF_UP) {
m_freem (m0);
return (EHOSTDOWN);
}
/* BPF writes need to be handled specially. */
if (dst->sa_family == AF_UNSPEC) {
bcopy(dst->sa_data, &af, sizeof(af));
dst->sa_family = af;
}
if (bpf_peers_present(ifp->if_bpf)) {
af = dst->sa_family;
bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m0);
}
/* prepend sockaddr? this may abort if the mbuf allocation fails */
if (cached_tun_flags & TUN_LMODE) {
/* allocate space for sockaddr */
M_PREPEND(m0, dst->sa_len, M_DONTWAIT);
/* if allocation failed drop packet */
if (m0 == NULL) {
ifp->if_iqdrops++;
ifp->if_oerrors++;
return (ENOBUFS);
} else {
bcopy(dst, m0->m_data, dst->sa_len);
}
}
if (cached_tun_flags & TUN_IFHEAD) {
/* Prepend the address family */
M_PREPEND(m0, 4, M_DONTWAIT);
/* if allocation failed drop packet */
if (m0 == NULL) {
ifp->if_iqdrops++;
ifp->if_oerrors++;
return (ENOBUFS);
} else
*(u_int32_t *)m0->m_data = htonl(dst->sa_family);
} else {
#ifdef INET
if (dst->sa_family != AF_INET)
#endif
{
m_freem(m0);
return (EAFNOSUPPORT);
}
}
IFQ_HANDOFF(ifp, m0, error);
if (error) {
ifp->if_collisions++;
return (ENOBUFS);
}
ifp->if_opackets++;
return (0);
}
/*
* the cdevsw interface is now pretty minimal.
*/
static int
tunioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag, struct thread *td)
{
int s;
int error;
struct tun_softc *tp = dev->si_drv1;
struct tuninfo *tunp;
switch (cmd) {
case TUNSIFINFO:
tunp = (struct tuninfo *)data;
if (tunp->mtu < IF_MINMTU)
return (EINVAL);
if (TUN2IFP(tp)->if_mtu != tunp->mtu
&& (error = suser(td)) != 0)
return (error);
TUN2IFP(tp)->if_mtu = tunp->mtu;
TUN2IFP(tp)->if_type = tunp->type;
TUN2IFP(tp)->if_baudrate = tunp->baudrate;
break;
case TUNGIFINFO:
tunp = (struct tuninfo *)data;
tunp->mtu = TUN2IFP(tp)->if_mtu;
tunp->type = TUN2IFP(tp)->if_type;
tunp->baudrate = TUN2IFP(tp)->if_baudrate;
break;
case TUNSDEBUG:
tundebug = *(int *)data;
break;
case TUNGDEBUG:
*(int *)data = tundebug;
break;
case TUNSLMODE:
mtx_lock(&tp->tun_mtx);
if (*(int *)data) {
tp->tun_flags |= TUN_LMODE;
tp->tun_flags &= ~TUN_IFHEAD;
} else
tp->tun_flags &= ~TUN_LMODE;
mtx_unlock(&tp->tun_mtx);
break;
case TUNSIFHEAD:
mtx_lock(&tp->tun_mtx);
if (*(int *)data) {
tp->tun_flags |= TUN_IFHEAD;
tp->tun_flags &= ~TUN_LMODE;
} else
tp->tun_flags &= ~TUN_IFHEAD;
mtx_unlock(&tp->tun_mtx);
break;
case TUNGIFHEAD:
/* Could be unlocked read? */
mtx_lock(&tp->tun_mtx);
*(int *)data = (tp->tun_flags & TUN_IFHEAD) ? 1 : 0;
mtx_unlock(&tp->tun_mtx);
break;
case TUNSIFMODE:
/* deny this if UP */
if (TUN2IFP(tp)->if_flags & IFF_UP)
return(EBUSY);
switch (*(int *)data & ~IFF_MULTICAST) {
case IFF_POINTOPOINT:
case IFF_BROADCAST:
TUN2IFP(tp)->if_flags &=
~(IFF_BROADCAST|IFF_POINTOPOINT|IFF_MULTICAST);
TUN2IFP(tp)->if_flags |= *(int *)data;
break;
default:
return(EINVAL);
}
break;
case TUNSIFPID:
mtx_lock(&tp->tun_mtx);
tp->tun_pid = curthread->td_proc->p_pid;
mtx_unlock(&tp->tun_mtx);
break;
case FIONBIO:
break;
case FIOASYNC:
mtx_lock(&tp->tun_mtx);
if (*(int *)data)
tp->tun_flags |= TUN_ASYNC;
else
tp->tun_flags &= ~TUN_ASYNC;
mtx_unlock(&tp->tun_mtx);
break;
case FIONREAD:
s = splimp();
if (!IFQ_IS_EMPTY(&TUN2IFP(tp)->if_snd)) {
struct mbuf *mb;
IFQ_LOCK(&TUN2IFP(tp)->if_snd);
IFQ_POLL_NOLOCK(&TUN2IFP(tp)->if_snd, mb);
for( *(int *)data = 0; mb != 0; mb = mb->m_next)
*(int *)data += mb->m_len;
IFQ_UNLOCK(&TUN2IFP(tp)->if_snd);
} 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(struct cdev *dev, struct uio *uio, int flag)
{
struct tun_softc *tp = dev->si_drv1;
struct ifnet *ifp = TUN2IFP(tp);
struct mbuf *m;
int error=0, len, s;
TUNDEBUG (ifp, "read\n");
mtx_lock(&tp->tun_mtx);
if ((tp->tun_flags & TUN_READY) != TUN_READY) {
mtx_unlock(&tp->tun_mtx);
TUNDEBUG (ifp, "not ready 0%o\n", tp->tun_flags);
return (EHOSTDOWN);
}
tp->tun_flags &= ~TUN_RWAIT;
mtx_unlock(&tp->tun_mtx);
s = splimp();
do {
IFQ_DEQUEUE(&ifp->if_snd, m);
if (m == NULL) {
if (flag & O_NONBLOCK) {
splx(s);
return (EWOULDBLOCK);
}
mtx_lock(&tp->tun_mtx);
tp->tun_flags |= TUN_RWAIT;
mtx_unlock(&tp->tun_mtx);
if((error = tsleep(tp, PCATCH | (PZERO + 1),
"tunread", 0)) != 0) {
splx(s);
return (error);
}
}
} while (m == NULL);
splx(s);
while (m && uio->uio_resid > 0 && error == 0) {
len = min(uio->uio_resid, m->m_len);
if (len != 0)
error = uiomove(mtod(m, void *), len, uio);
m = m_free(m);
}
if (m) {
TUNDEBUG(ifp, "Dropping mbuf\n");
m_freem(m);
}
return (error);
}
/*
* the cdevsw write interface - an atomic write is a packet - or else!
*/
static int
tunwrite(struct cdev *dev, struct uio *uio, int flag)
{
struct tun_softc *tp = dev->si_drv1;
struct ifnet *ifp = TUN2IFP(tp);
struct mbuf *m;
int error = 0;
uint32_t family;
int isr;
TUNDEBUG(ifp, "tunwrite\n");
if ((ifp->if_flags & IFF_UP) != IFF_UP)
/* ignore silently */
return (0);
if (uio->uio_resid == 0)
return (0);
if (uio->uio_resid < 0 || uio->uio_resid > TUNMRU) {
TUNDEBUG(ifp, "len=%d!\n", uio->uio_resid);
return (EIO);
}
if ((m = m_uiotombuf(uio, M_DONTWAIT, 0, 0)) == NULL) {
ifp->if_ierrors++;
return (error);
}
m->m_pkthdr.rcvif = ifp;
#ifdef MAC
mac_create_mbuf_from_ifnet(ifp, m);
#endif
/* Could be unlocked read? */
mtx_lock(&tp->tun_mtx);
if (tp->tun_flags & TUN_IFHEAD) {
mtx_unlock(&tp->tun_mtx);
if (m->m_len < sizeof(family) &&
(m = m_pullup(m, sizeof(family))) == NULL)
return (ENOBUFS);
family = ntohl(*mtod(m, u_int32_t *));
m_adj(m, sizeof(family));
} else {
mtx_unlock(&tp->tun_mtx);
family = AF_INET;
}
BPF_MTAP2(ifp, &family, sizeof(family), m);
switch (family) {
#ifdef INET
case AF_INET:
isr = NETISR_IP;
break;
#endif
#ifdef INET6
case AF_INET6:
isr = NETISR_IPV6;
break;
#endif
#ifdef IPX
case AF_IPX:
isr = NETISR_IPX;
break;
#endif
#ifdef NETATALK
case AF_APPLETALK:
isr = NETISR_ATALK2;
break;
#endif
default:
m_freem(m);
return (EAFNOSUPPORT);
}
/* First chunk of an mbuf contains good junk */
if (harvest.point_to_point)
random_harvest(m, 16, 3, 0, RANDOM_NET);
ifp->if_ibytes += m->m_pkthdr.len;
ifp->if_ipackets++;
netisr_dispatch(isr, m);
return (0);
}
/*
* 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(struct cdev *dev, int events, struct thread *td)
{
int s;
struct tun_softc *tp = dev->si_drv1;
struct ifnet *ifp = TUN2IFP(tp);
int revents = 0;
struct mbuf *m;
s = splimp();
TUNDEBUG(ifp, "tunpoll\n");
if (events & (POLLIN | POLLRDNORM)) {
IFQ_LOCK(&ifp->if_snd);
IFQ_POLL_NOLOCK(&ifp->if_snd, m);
if (m != NULL) {
TUNDEBUG(ifp, "tunpoll q=%d\n", ifp->if_snd.ifq_len);
revents |= events & (POLLIN | POLLRDNORM);
} else {
TUNDEBUG(ifp, "tunpoll waiting\n");
selrecord(td, &tp->tun_rsel);
}
IFQ_UNLOCK(&ifp->if_snd);
}
if (events & (POLLOUT | POLLWRNORM))
revents |= events & (POLLOUT | POLLWRNORM);
splx(s);
return (revents);
}
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