/* $NetBSD: if_tap.c,v 1.113.2.1 2019/11/01 09:34:27 martin Exp $ */
/*
* Copyright (c) 2003, 2004, 2008, 2009 The NetBSD Foundation.
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* tap(4) is a virtual Ethernet interface. It appears as a real Ethernet
* device to the system, but can also be accessed by userland through a
* character device interface, which allows reading and injecting frames.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_tap.c,v 1.113.2.1 2019/11/01 09:34:27 martin Exp $");
#if defined(_KERNEL_OPT)
#include "opt_modular.h"
#endif
#include <sys/param.h>
#include <sys/atomic.h>
#include <sys/conf.h>
#include <sys/cprng.h>
#include <sys/device.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/intr.h>
#include <sys/kauth.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/poll.h>
#include <sys/proc.h>
#include <sys/select.h>
#include <sys/sockio.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_ether.h>
#include <net/if_media.h>
#include <net/if_tap.h>
#include <net/bpf.h>
#include "ioconf.h"
/*
* sysctl node management
*
* It's not really possible to use a SYSCTL_SETUP block with
* current module implementation, so it is easier to just define
* our own function.
*
* The handler function is a "helper" in Andrew Brown's sysctl
* framework terminology. It is used as a gateway for sysctl
* requests over the nodes.
*
* tap_log allows the module to log creations of nodes and
* destroy them all at once using sysctl_teardown.
*/
static int tap_node;
static int tap_sysctl_handler(SYSCTLFN_PROTO);
static void sysctl_tap_setup(struct sysctllog **);
/*
* Since we're an Ethernet device, we need the 2 following
* components: a struct ethercom and a struct ifmedia
* since we don't attach a PHY to ourselves.
* We could emulate one, but there's no real point.
*/
struct tap_softc {
device_t sc_dev;
struct ifmedia sc_im;
struct ethercom sc_ec;
int sc_flags;
#define TAP_INUSE 0x00000001 /* tap device can only be opened once */
#define TAP_ASYNCIO 0x00000002 /* user is using async I/O (SIGIO) on the device */
#define TAP_NBIO 0x00000004 /* user wants calls to avoid blocking */
#define TAP_GOING 0x00000008 /* interface is being destroyed */
struct selinfo sc_rsel;
pid_t sc_pgid; /* For async. IO */
kmutex_t sc_lock;
kcondvar_t sc_cv;
void *sc_sih;
struct timespec sc_atime;
struct timespec sc_mtime;
struct timespec sc_btime;
};
/* autoconf(9) glue */
static int tap_match(device_t, cfdata_t, void *);
static void tap_attach(device_t, device_t, void *);
static int tap_detach(device_t, int);
CFATTACH_DECL_NEW(tap, sizeof(struct tap_softc),
tap_match, tap_attach, tap_detach, NULL);
extern struct cfdriver tap_cd;
/* Real device access routines */
static int tap_dev_close(struct tap_softc *);
static int tap_dev_read(int, struct uio *, int);
static int tap_dev_write(int, struct uio *, int);
static int tap_dev_ioctl(int, u_long, void *, struct lwp *);
static int tap_dev_poll(int, int, struct lwp *);
static int tap_dev_kqfilter(int, struct knote *);
/* Fileops access routines */
static int tap_fops_close(file_t *);
static int tap_fops_read(file_t *, off_t *, struct uio *,
kauth_cred_t, int);
static int tap_fops_write(file_t *, off_t *, struct uio *,
kauth_cred_t, int);
static int tap_fops_ioctl(file_t *, u_long, void *);
static int tap_fops_poll(file_t *, int);
static int tap_fops_stat(file_t *, struct stat *);
static int tap_fops_kqfilter(file_t *, struct knote *);
static const struct fileops tap_fileops = {
.fo_name = "tap",
.fo_read = tap_fops_read,
.fo_write = tap_fops_write,
.fo_ioctl = tap_fops_ioctl,
.fo_fcntl = fnullop_fcntl,
.fo_poll = tap_fops_poll,
.fo_stat = tap_fops_stat,
.fo_close = tap_fops_close,
.fo_kqfilter = tap_fops_kqfilter,
.fo_restart = fnullop_restart,
};
/* Helper for cloning open() */
static int tap_dev_cloner(struct lwp *);
/* Character device routines */
static int tap_cdev_open(dev_t, int, int, struct lwp *);
static int tap_cdev_close(dev_t, int, int, struct lwp *);
static int tap_cdev_read(dev_t, struct uio *, int);
static int tap_cdev_write(dev_t, struct uio *, int);
static int tap_cdev_ioctl(dev_t, u_long, void *, int, struct lwp *);
static int tap_cdev_poll(dev_t, int, struct lwp *);
static int tap_cdev_kqfilter(dev_t, struct knote *);
const struct cdevsw tap_cdevsw = {
.d_open = tap_cdev_open,
.d_close = tap_cdev_close,
.d_read = tap_cdev_read,
.d_write = tap_cdev_write,
.d_ioctl = tap_cdev_ioctl,
.d_stop = nostop,
.d_tty = notty,
.d_poll = tap_cdev_poll,
.d_mmap = nommap,
.d_kqfilter = tap_cdev_kqfilter,
.d_discard = nodiscard,
.d_flag = D_OTHER | D_MPSAFE
};
#define TAP_CLONER 0xfffff /* Maximal minor value */
/* kqueue-related routines */
static void tap_kqdetach(struct knote *);
static int tap_kqread(struct knote *, long);
/*
* Those are needed by the if_media interface.
*/
static int tap_mediachange(struct ifnet *);
static void tap_mediastatus(struct ifnet *, struct ifmediareq *);
/*
* Those are needed by the ifnet interface, and would typically be
* there for any network interface driver.
* Some other routines are optional: watchdog and drain.
*/
static void tap_start(struct ifnet *);
static void tap_stop(struct ifnet *, int);
static int tap_init(struct ifnet *);
static int tap_ioctl(struct ifnet *, u_long, void *);
/* Internal functions */
static int tap_lifaddr(struct ifnet *, u_long, struct ifaliasreq *);
static void tap_softintr(void *);
/*
* tap is a clonable interface, although it is highly unrealistic for
* an Ethernet device.
*
* Here are the bits needed for a clonable interface.
*/
static int tap_clone_create(struct if_clone *, int);
static int tap_clone_destroy(struct ifnet *);
struct if_clone tap_cloners = IF_CLONE_INITIALIZER("tap",
tap_clone_create,
tap_clone_destroy);
/* Helper functions shared by the two cloning code paths */
static struct tap_softc * tap_clone_creator(int);
int tap_clone_destroyer(device_t);
static struct sysctllog *tap_sysctl_clog;
#ifdef _MODULE
devmajor_t tap_bmajor = -1, tap_cmajor = -1;
#endif
static u_int tap_count;
void
tapattach(int n)
{
/*
* Nothing to do here, initialization is handled by the
* module initialization code in tapinit() below).
*/
}
static void
tapinit(void)
{
int error = config_cfattach_attach(tap_cd.cd_name, &tap_ca);
if (error) {
aprint_error("%s: unable to register cfattach\n",
tap_cd.cd_name);
(void)config_cfdriver_detach(&tap_cd);
return;
}
if_clone_attach(&tap_cloners);
sysctl_tap_setup(&tap_sysctl_clog);
#ifdef _MODULE
devsw_attach("tap", NULL, &tap_bmajor, &tap_cdevsw, &tap_cmajor);
#endif
}
static int
tapdetach(void)
{
int error = 0;
if_clone_detach(&tap_cloners);
#ifdef _MODULE
error = devsw_detach(NULL, &tap_cdevsw);
if (error != 0)
goto out2;
#endif
if (tap_count != 0) {
error = EBUSY;
goto out1;
}
error = config_cfattach_detach(tap_cd.cd_name, &tap_ca);
if (error != 0)
goto out1;
sysctl_teardown(&tap_sysctl_clog);
return 0;
out1:
#ifdef _MODULE
devsw_attach("tap", NULL, &tap_bmajor, &tap_cdevsw, &tap_cmajor);
out2:
#endif
if_clone_attach(&tap_cloners);
return error;
}
/* Pretty much useless for a pseudo-device */
static int
tap_match(device_t parent, cfdata_t cfdata, void *arg)
{
return 1;
}
void
tap_attach(device_t parent, device_t self, void *aux)
{
struct tap_softc *sc = device_private(self);
struct ifnet *ifp;
const struct sysctlnode *node;
int error;
uint8_t enaddr[ETHER_ADDR_LEN] =
{ 0xf2, 0x0b, 0xa4, 0xff, 0xff, 0xff };
char enaddrstr[3 * ETHER_ADDR_LEN];
sc->sc_dev = self;
sc->sc_sih = NULL;
getnanotime(&sc->sc_btime);
sc->sc_atime = sc->sc_mtime = sc->sc_btime;
sc->sc_flags = 0;
selinit(&sc->sc_rsel);
cv_init(&sc->sc_cv, "tapread");
mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_NET);
if (!pmf_device_register(self, NULL, NULL))
aprint_error_dev(self, "couldn't establish power handler\n");
/*
* In order to obtain unique initial Ethernet address on a host,
* do some randomisation. It's not meant for anything but avoiding
* hard-coding an address.
*/
cprng_fast(&enaddr[3], 3);
aprint_verbose_dev(self, "Ethernet address %s\n",
ether_snprintf(enaddrstr, sizeof(enaddrstr), enaddr));
/*
* Why 1000baseT? Why not? You can add more.
*
* Note that there are 3 steps: init, one or several additions to
* list of supported media, and in the end, the selection of one
* of them.
*/
sc->sc_ec.ec_ifmedia = &sc->sc_im;
ifmedia_init(&sc->sc_im, 0, tap_mediachange, tap_mediastatus);
ifmedia_add(&sc->sc_im, IFM_ETHER | IFM_1000_T, 0, NULL);
ifmedia_add(&sc->sc_im, IFM_ETHER | IFM_1000_T | IFM_FDX, 0, NULL);
ifmedia_add(&sc->sc_im, IFM_ETHER | IFM_100_TX, 0, NULL);
ifmedia_add(&sc->sc_im, IFM_ETHER | IFM_100_TX | IFM_FDX, 0, NULL);
ifmedia_add(&sc->sc_im, IFM_ETHER | IFM_10_T, 0, NULL);
ifmedia_add(&sc->sc_im, IFM_ETHER | IFM_10_T | IFM_FDX, 0, NULL);
ifmedia_add(&sc->sc_im, IFM_ETHER | IFM_AUTO, 0, NULL);
ifmedia_set(&sc->sc_im, IFM_ETHER | IFM_AUTO);
/*
* One should note that an interface must do multicast in order
* to support IPv6.
*/
ifp = &sc->sc_ec.ec_if;
strcpy(ifp->if_xname, device_xname(self));
ifp->if_softc = sc;
ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
ifp->if_extflags = IFEF_NO_LINK_STATE_CHANGE;
#ifdef NET_MPSAFE
ifp->if_extflags |= IFEF_MPSAFE;
#endif
ifp->if_ioctl = tap_ioctl;
ifp->if_start = tap_start;
ifp->if_stop = tap_stop;
ifp->if_init = tap_init;
IFQ_SET_READY(&ifp->if_snd);
sc->sc_ec.ec_capabilities = ETHERCAP_VLAN_MTU | ETHERCAP_JUMBO_MTU;
/* Those steps are mandatory for an Ethernet driver. */
error = if_initialize(ifp);
if (error != 0) {
aprint_error_dev(self, "if_initialize failed(%d)\n", error);
ifmedia_removeall(&sc->sc_im);
pmf_device_deregister(self);
mutex_destroy(&sc->sc_lock);
seldestroy(&sc->sc_rsel);
return; /* Error */
}
ifp->if_percpuq = if_percpuq_create(ifp);
ether_ifattach(ifp, enaddr);
if_register(ifp);
/*
* Add a sysctl node for that interface.
*
* The pointer transmitted is not a string, but instead a pointer to
* the softc structure, which we can use to build the string value on
* the fly in the helper function of the node. See the comments for
* tap_sysctl_handler for details.
*
* Usually sysctl_createv is called with CTL_CREATE as the before-last
* component. However, we can allocate a number ourselves, as we are
* the only consumer of the net.link.<iface> node. In this case, the
* unit number is conveniently used to number the node. CTL_CREATE
* would just work, too.
*/
if ((error = sysctl_createv(NULL, 0, NULL,
&node, CTLFLAG_READWRITE,
CTLTYPE_STRING, device_xname(self), NULL,
tap_sysctl_handler, 0, (void *)sc, 18,
CTL_NET, AF_LINK, tap_node, device_unit(sc->sc_dev),
CTL_EOL)) != 0)
aprint_error_dev(self,
"sysctl_createv returned %d, ignoring\n", error);
}
/*
* When detaching, we do the inverse of what is done in the attach
* routine, in reversed order.
*/
static int
tap_detach(device_t self, int flags)
{
struct tap_softc *sc = device_private(self);
struct ifnet *ifp = &sc->sc_ec.ec_if;
int error;
sc->sc_flags |= TAP_GOING;
tap_stop(ifp, 1);
if_down(ifp);
if (sc->sc_sih != NULL) {
softint_disestablish(sc->sc_sih);
sc->sc_sih = NULL;
}
/*
* Destroying a single leaf is a very straightforward operation using
* sysctl_destroyv. One should be sure to always end the path with
* CTL_EOL.
*/
if ((error = sysctl_destroyv(NULL, CTL_NET, AF_LINK, tap_node,
device_unit(sc->sc_dev), CTL_EOL)) != 0)
aprint_error_dev(self,
"sysctl_destroyv returned %d, ignoring\n", error);
ether_ifdetach(ifp);
if_detach(ifp);
ifmedia_removeall(&sc->sc_im);
seldestroy(&sc->sc_rsel);
mutex_destroy(&sc->sc_lock);
cv_destroy(&sc->sc_cv);
pmf_device_deregister(self);
return 0;
}
/*
* This function is called by the ifmedia layer to notify the driver
* that the user requested a media change. A real driver would
* reconfigure the hardware.
*/
static int
tap_mediachange(struct ifnet *ifp)
{
return 0;
}
/*
* Here the user asks for the currently used media.
*/
static void
tap_mediastatus(struct ifnet *ifp, struct ifmediareq *imr)
{
struct tap_softc *sc = (struct tap_softc *)ifp->if_softc;
imr->ifm_active = sc->sc_im.ifm_cur->ifm_media;
}
/*
* This is the function where we SEND packets.
*
* There is no 'receive' equivalent. A typical driver will get
* interrupts from the hardware, and from there will inject new packets
* into the network stack.
*
* Once handled, a packet must be freed. A real driver might not be able
* to fit all the pending packets into the hardware, and is allowed to
* return before having sent all the packets. It should then use the
* if_flags flag IFF_OACTIVE to notify the upper layer.
*
* There are also other flags one should check, such as IFF_PAUSE.
*
* It is our duty to make packets available to BPF listeners.
*
* You should be aware that this function is called by the Ethernet layer
* at splnet().
*
* When the device is opened, we have to pass the packet(s) to the
* userland. For that we stay in OACTIVE mode while the userland gets
* the packets, and we send a signal to the processes waiting to read.
*
* wakeup(sc) is the counterpart to the tsleep call in
* tap_dev_read, while selnotify() is used for kevent(2) and
* poll(2) (which includes select(2)) listeners.
*/
static void
tap_start(struct ifnet *ifp)
{
struct tap_softc *sc = (struct tap_softc *)ifp->if_softc;
struct mbuf *m0;
mutex_enter(&sc->sc_lock);
if ((sc->sc_flags & TAP_INUSE) == 0) {
/* Simply drop packets */
for (;;) {
IFQ_DEQUEUE(&ifp->if_snd, m0);
if (m0 == NULL)
goto done;
ifp->if_opackets++;
bpf_mtap(ifp, m0, BPF_D_OUT);
m_freem(m0);
}
} else if (!IFQ_IS_EMPTY(&ifp->if_snd)) {
ifp->if_flags |= IFF_OACTIVE;
cv_broadcast(&sc->sc_cv);
selnotify(&sc->sc_rsel, 0, 1);
if (sc->sc_flags & TAP_ASYNCIO) {
kpreempt_disable();
softint_schedule(sc->sc_sih);
kpreempt_enable();
}
}
done:
mutex_exit(&sc->sc_lock);
}
static void
tap_softintr(void *cookie)
{
struct tap_softc *sc;
struct ifnet *ifp;
int a, b;
sc = cookie;
if (sc->sc_flags & TAP_ASYNCIO) {
ifp = &sc->sc_ec.ec_if;
if (ifp->if_flags & IFF_RUNNING) {
a = POLL_IN;
b = POLLIN | POLLRDNORM;
} else {
a = POLL_HUP;
b = 0;
}
fownsignal(sc->sc_pgid, SIGIO, a, b, NULL);
}
}
/*
* A typical driver will only contain the following handlers for
* ioctl calls, except SIOCSIFPHYADDR.
* The latter is a hack I used to set the Ethernet address of the
* faked device.
*
* Note that both ifmedia_ioctl() and ether_ioctl() have to be
* called under splnet().
*/
static int
tap_ioctl(struct ifnet *ifp, u_long cmd, void *data)
{
int s, error;
s = splnet();
switch (cmd) {
case SIOCSIFPHYADDR:
error = tap_lifaddr(ifp, cmd, (struct ifaliasreq *)data);
break;
default:
error = ether_ioctl(ifp, cmd, data);
if (error == ENETRESET)
error = 0;
break;
}
splx(s);
return error;
}
/*
* Helper function to set Ethernet address. This has been replaced by
* the generic SIOCALIFADDR ioctl on a PF_LINK socket.
*/
static int
tap_lifaddr(struct ifnet *ifp, u_long cmd, struct ifaliasreq *ifra)
{
const struct sockaddr *sa = &ifra->ifra_addr;
if (sa->sa_family != AF_LINK)
return EINVAL;
if_set_sadl(ifp, sa->sa_data, ETHER_ADDR_LEN, false);
return 0;
}
/*
* _init() would typically be called when an interface goes up,
* meaning it should configure itself into the state in which it
* can send packets.
*/
static int
tap_init(struct ifnet *ifp)
{
ifp->if_flags |= IFF_RUNNING;
tap_start(ifp);
return 0;
}
/*
* _stop() is called when an interface goes down. It is our
* responsability to validate that state by clearing the
* IFF_RUNNING flag.
*
* We have to wake up all the sleeping processes to have the pending
* read requests cancelled.
*/
static void
tap_stop(struct ifnet *ifp, int disable)
{
struct tap_softc *sc = (struct tap_softc *)ifp->if_softc;
mutex_enter(&sc->sc_lock);
ifp->if_flags &= ~IFF_RUNNING;
cv_broadcast(&sc->sc_cv);
selnotify(&sc->sc_rsel, 0, 1);
if (sc->sc_flags & TAP_ASYNCIO) {
kpreempt_disable();
softint_schedule(sc->sc_sih);
kpreempt_enable();
}
mutex_exit(&sc->sc_lock);
}
/*
* The 'create' command of ifconfig can be used to create
* any numbered instance of a given device. Thus we have to
* make sure we have enough room in cd_devs to create the
* user-specified instance. config_attach_pseudo will do this
* for us.
*/
static int
tap_clone_create(struct if_clone *ifc, int unit)
{
if (tap_clone_creator(unit) == NULL) {
aprint_error("%s%d: unable to attach an instance\n",
tap_cd.cd_name, unit);
return ENXIO;
}
atomic_inc_uint(&tap_count);
return 0;
}
/*
* tap(4) can be cloned by two ways:
* using 'ifconfig tap0 create', which will use the network
* interface cloning API, and call tap_clone_create above.
* opening the cloning device node, whose minor number is TAP_CLONER.
* See below for an explanation on how this part work.
*/
static struct tap_softc *
tap_clone_creator(int unit)
{
cfdata_t cf;
cf = kmem_alloc(sizeof(*cf), KM_SLEEP);
cf->cf_name = tap_cd.cd_name;
cf->cf_atname = tap_ca.ca_name;
if (unit == -1) {
/* let autoconf find the first free one */
cf->cf_unit = 0;
cf->cf_fstate = FSTATE_STAR;
} else {
cf->cf_unit = unit;
cf->cf_fstate = FSTATE_NOTFOUND;
}
return device_private(config_attach_pseudo(cf));
}
/*
* The clean design of if_clone and autoconf(9) makes that part
* really straightforward. The second argument of config_detach
* means neither QUIET nor FORCED.
*/
static int
tap_clone_destroy(struct ifnet *ifp)
{
struct tap_softc *sc = ifp->if_softc;
int error = tap_clone_destroyer(sc->sc_dev);
if (error == 0)
atomic_dec_uint(&tap_count);
return error;
}
int
tap_clone_destroyer(device_t dev)
{
cfdata_t cf = device_cfdata(dev);
int error;
if ((error = config_detach(dev, 0)) != 0)
aprint_error_dev(dev, "unable to detach instance\n");
kmem_free(cf, sizeof(*cf));
return error;
}
/*
* tap(4) is a bit of an hybrid device. It can be used in two different
* ways:
* 1. ifconfig tapN create, then use /dev/tapN to read/write off it.
* 2. open /dev/tap, get a new interface created and read/write off it.
* That interface is destroyed when the process that had it created exits.
*
* The first way is managed by the cdevsw structure, and you access interfaces
* through a (major, minor) mapping: tap4 is obtained by the minor number
* 4. The entry points for the cdevsw interface are prefixed by tap_cdev_.
*
* The second way is the so-called "cloning" device. It's a special minor
* number (chosen as the maximal number, to allow as much tap devices as
* possible). The user first opens the cloner (e.g., /dev/tap), and that
* call ends in tap_cdev_open. The actual place where it is handled is
* tap_dev_cloner.
*
* An tap device cannot be opened more than once at a time, so the cdevsw
* part of open() does nothing but noting that the interface is being used and
* hence ready to actually handle packets.
*/
static int
tap_cdev_open(dev_t dev, int flags, int fmt, struct lwp *l)
{
struct tap_softc *sc;
if (minor(dev) == TAP_CLONER)
return tap_dev_cloner(l);
sc = device_lookup_private(&tap_cd, minor(dev));
if (sc == NULL)
return ENXIO;
/* The device can only be opened once */
if (sc->sc_flags & TAP_INUSE)
return EBUSY;
sc->sc_flags |= TAP_INUSE;
return 0;
}
/*
* There are several kinds of cloning devices, and the most simple is the one
* tap(4) uses. What it does is change the file descriptor with a new one,
* with its own fileops structure (which maps to the various read, write,
* ioctl functions). It starts allocating a new file descriptor with falloc,
* then actually creates the new tap devices.
*
* Once those two steps are successful, we can re-wire the existing file
* descriptor to its new self. This is done with fdclone(): it fills the fp
* structure as needed (notably f_devunit gets filled with the fifth parameter
* passed, the unit of the tap device which will allows us identifying the
* device later), and returns EMOVEFD.
*
* That magic value is interpreted by sys_open() which then replaces the
* current file descriptor by the new one (through a magic member of struct
* lwp, l_dupfd).
*
* The tap device is flagged as being busy since it otherwise could be
* externally accessed through the corresponding device node with the cdevsw
* interface.
*/
static int
tap_dev_cloner(struct lwp *l)
{
struct tap_softc *sc;
file_t *fp;
int error, fd;
if ((error = fd_allocfile(&fp, &fd)) != 0)
return error;
if ((sc = tap_clone_creator(-1)) == NULL) {
fd_abort(curproc, fp, fd);
return ENXIO;
}
sc->sc_flags |= TAP_INUSE;
return fd_clone(fp, fd, FREAD | FWRITE, &tap_fileops,
(void *)(intptr_t)device_unit(sc->sc_dev));
}
/*
* While all other operations (read, write, ioctl, poll and kqfilter) are
* really the same whether we are in cdevsw or fileops mode, the close()
* function is slightly different in the two cases.
*
* As for the other, the core of it is shared in tap_dev_close. What
* it does is sufficient for the cdevsw interface, but the cloning interface
* needs another thing: the interface is destroyed when the processes that
* created it closes it.
*/
static int
tap_cdev_close(dev_t dev, int flags, int fmt, struct lwp *l)
{
struct tap_softc *sc = device_lookup_private(&tap_cd, minor(dev));
if (sc == NULL)
return ENXIO;
return tap_dev_close(sc);
}
/*
* It might happen that the administrator used ifconfig to externally destroy
* the interface. In that case, tap_fops_close will be called while
* tap_detach is already happening. If we called it again from here, we
* would dead lock. TAP_GOING ensures that this situation doesn't happen.
*/
static int
tap_fops_close(file_t *fp)
{
struct tap_softc *sc;
int unit = fp->f_devunit;
int error;
sc = device_lookup_private(&tap_cd, unit);
if (sc == NULL)
return ENXIO;
/* tap_dev_close currently always succeeds, but it might not
* always be the case. */
KERNEL_LOCK(1, NULL);
if ((error = tap_dev_close(sc)) != 0) {
KERNEL_UNLOCK_ONE(NULL);
return error;
}
/* Destroy the device now that it is no longer useful,
* unless it's already being destroyed. */
if ((sc->sc_flags & TAP_GOING) != 0) {
KERNEL_UNLOCK_ONE(NULL);
return 0;
}
error = tap_clone_destroyer(sc->sc_dev);
KERNEL_UNLOCK_ONE(NULL);
return error;
}
static int
tap_dev_close(struct tap_softc *sc)
{
struct ifnet *ifp;
int s;
s = splnet();
/* Let tap_start handle packets again */
ifp = &sc->sc_ec.ec_if;
ifp->if_flags &= ~IFF_OACTIVE;
/* Purge output queue */
if (!(IFQ_IS_EMPTY(&ifp->if_snd))) {
struct mbuf *m;
for (;;) {
IFQ_DEQUEUE(&ifp->if_snd, m);
if (m == NULL)
break;
ifp->if_opackets++;
bpf_mtap(ifp, m, BPF_D_OUT);
m_freem(m);
}
}
splx(s);
if (sc->sc_sih != NULL) {
softint_disestablish(sc->sc_sih);
sc->sc_sih = NULL;
}
sc->sc_flags &= ~(TAP_INUSE | TAP_ASYNCIO);
return 0;
}
static int
tap_cdev_read(dev_t dev, struct uio *uio, int flags)
{
return tap_dev_read(minor(dev), uio, flags);
}
static int
tap_fops_read(file_t *fp, off_t *offp, struct uio *uio,
kauth_cred_t cred, int flags)
{
int error;
KERNEL_LOCK(1, NULL);
error = tap_dev_read(fp->f_devunit, uio, flags);
KERNEL_UNLOCK_ONE(NULL);
return error;
}
static int
tap_dev_read(int unit, struct uio *uio, int flags)
{
struct tap_softc *sc = device_lookup_private(&tap_cd, unit);
struct ifnet *ifp;
struct mbuf *m, *n;
int error = 0;
if (sc == NULL)
return ENXIO;
getnanotime(&sc->sc_atime);
ifp = &sc->sc_ec.ec_if;
if ((ifp->if_flags & IFF_UP) == 0)
return EHOSTDOWN;
/* In the TAP_NBIO case, we have to make sure we won't be sleeping */
if ((sc->sc_flags & TAP_NBIO) != 0) {
if (!mutex_tryenter(&sc->sc_lock))
return EWOULDBLOCK;
} else
mutex_enter(&sc->sc_lock);
if (IFQ_IS_EMPTY(&ifp->if_snd)) {
ifp->if_flags &= ~IFF_OACTIVE;
if (sc->sc_flags & TAP_NBIO)
error = EWOULDBLOCK;
else
error = cv_wait_sig(&sc->sc_cv, &sc->sc_lock);
if (error != 0) {
mutex_exit(&sc->sc_lock);
return error;
}
/* The device might have been downed */
if ((ifp->if_flags & IFF_UP) == 0) {
mutex_exit(&sc->sc_lock);
return EHOSTDOWN;
}
}
IFQ_DEQUEUE(&ifp->if_snd, m);
mutex_exit(&sc->sc_lock);
ifp->if_flags &= ~IFF_OACTIVE;
if (m == NULL) {
error = 0;
goto out;
}
ifp->if_opackets++;
bpf_mtap(ifp, m, BPF_D_OUT);
/*
* One read is one packet.
*/
do {
error = uiomove(mtod(m, void *),
uimin(m->m_len, uio->uio_resid), uio);
m = n = m_free(m);
} while (m != NULL && uio->uio_resid > 0 && error == 0);
if (m != NULL)
m_freem(m);
out:
return error;
}
static int
tap_fops_stat(file_t *fp, struct stat *st)
{
int error = 0;
struct tap_softc *sc;
int unit = fp->f_devunit;
(void)memset(st, 0, sizeof(*st));
KERNEL_LOCK(1, NULL);
sc = device_lookup_private(&tap_cd, unit);
if (sc == NULL) {
error = ENXIO;
goto out;
}
st->st_dev = makedev(cdevsw_lookup_major(&tap_cdevsw), unit);
st->st_atimespec = sc->sc_atime;
st->st_mtimespec = sc->sc_mtime;
st->st_ctimespec = st->st_birthtimespec = sc->sc_btime;
st->st_uid = kauth_cred_geteuid(fp->f_cred);
st->st_gid = kauth_cred_getegid(fp->f_cred);
out:
KERNEL_UNLOCK_ONE(NULL);
return error;
}
static int
tap_cdev_write(dev_t dev, struct uio *uio, int flags)
{
return tap_dev_write(minor(dev), uio, flags);
}
static int
tap_fops_write(file_t *fp, off_t *offp, struct uio *uio,
kauth_cred_t cred, int flags)
{
int error;
KERNEL_LOCK(1, NULL);
error = tap_dev_write(fp->f_devunit, uio, flags);
KERNEL_UNLOCK_ONE(NULL);
return error;
}
static int
tap_dev_write(int unit, struct uio *uio, int flags)
{
struct tap_softc *sc =
device_lookup_private(&tap_cd, unit);
struct ifnet *ifp;
struct mbuf *m, **mp;
int error = 0;
if (sc == NULL)
return ENXIO;
getnanotime(&sc->sc_mtime);
ifp = &sc->sc_ec.ec_if;
/* One write, one packet, that's the rule */
MGETHDR(m, M_DONTWAIT, MT_DATA);
if (m == NULL) {
ifp->if_ierrors++;
return ENOBUFS;
}
m->m_pkthdr.len = uio->uio_resid;
mp = &m;
while (error == 0 && uio->uio_resid > 0) {
if (*mp != m) {
MGET(*mp, M_DONTWAIT, MT_DATA);
if (*mp == NULL) {
error = ENOBUFS;
break;
}
}
(*mp)->m_len = uimin(MHLEN, uio->uio_resid);
error = uiomove(mtod(*mp, void *), (*mp)->m_len, uio);
mp = &(*mp)->m_next;
}
if (error) {
ifp->if_ierrors++;
m_freem(m);
return error;
}
m_set_rcvif(m, ifp);
if_percpuq_enqueue(ifp->if_percpuq, m);
return 0;
}
static int
tap_cdev_ioctl(dev_t dev, u_long cmd, void *data, int flags, struct lwp *l)
{
return tap_dev_ioctl(minor(dev), cmd, data, l);
}
static int
tap_fops_ioctl(file_t *fp, u_long cmd, void *data)
{
return tap_dev_ioctl(fp->f_devunit, cmd, data, curlwp);
}
static int
tap_dev_ioctl(int unit, u_long cmd, void *data, struct lwp *l)
{
struct tap_softc *sc = device_lookup_private(&tap_cd, unit);
if (sc == NULL)
return ENXIO;
switch (cmd) {
case FIONREAD:
{
struct ifnet *ifp = &sc->sc_ec.ec_if;
struct mbuf *m;
int s;
s = splnet();
IFQ_POLL(&ifp->if_snd, m);
if (m == NULL)
*(int *)data = 0;
else
*(int *)data = m->m_pkthdr.len;
splx(s);
return 0;
}
case TIOCSPGRP:
case FIOSETOWN:
return fsetown(&sc->sc_pgid, cmd, data);
case TIOCGPGRP:
case FIOGETOWN:
return fgetown(sc->sc_pgid, cmd, data);
case FIOASYNC:
if (*(int *)data) {
if (sc->sc_sih == NULL) {
sc->sc_sih = softint_establish(SOFTINT_CLOCK,
tap_softintr, sc);
if (sc->sc_sih == NULL)
return EBUSY; /* XXX */
}
sc->sc_flags |= TAP_ASYNCIO;
} else {
sc->sc_flags &= ~TAP_ASYNCIO;
if (sc->sc_sih != NULL) {
softint_disestablish(sc->sc_sih);
sc->sc_sih = NULL;
}
}
return 0;
case FIONBIO:
if (*(int *)data)
sc->sc_flags |= TAP_NBIO;
else
sc->sc_flags &= ~TAP_NBIO;
return 0;
case TAPGIFNAME:
{
struct ifreq *ifr = (struct ifreq *)data;
struct ifnet *ifp = &sc->sc_ec.ec_if;
strlcpy(ifr->ifr_name, ifp->if_xname, IFNAMSIZ);
return 0;
}
default:
return ENOTTY;
}
}
static int
tap_cdev_poll(dev_t dev, int events, struct lwp *l)
{
return tap_dev_poll(minor(dev), events, l);
}
static int
tap_fops_poll(file_t *fp, int events)
{
return tap_dev_poll(fp->f_devunit, events, curlwp);
}
static int
tap_dev_poll(int unit, int events, struct lwp *l)
{
struct tap_softc *sc = device_lookup_private(&tap_cd, unit);
int revents = 0;
if (sc == NULL)
return POLLERR;
if (events & (POLLIN | POLLRDNORM)) {
struct ifnet *ifp = &sc->sc_ec.ec_if;
struct mbuf *m;
int s;
s = splnet();
IFQ_POLL(&ifp->if_snd, m);
if (m != NULL)
revents |= events & (POLLIN | POLLRDNORM);
else {
mutex_spin_enter(&sc->sc_lock);
selrecord(l, &sc->sc_rsel);
mutex_spin_exit(&sc->sc_lock);
}
splx(s);
}
revents |= events & (POLLOUT | POLLWRNORM);
return revents;
}
static struct filterops tap_read_filterops = { 1, NULL, tap_kqdetach,
tap_kqread };
static struct filterops tap_seltrue_filterops = { 1, NULL, tap_kqdetach,
filt_seltrue };
static int
tap_cdev_kqfilter(dev_t dev, struct knote *kn)
{
return tap_dev_kqfilter(minor(dev), kn);
}
static int
tap_fops_kqfilter(file_t *fp, struct knote *kn)
{
return tap_dev_kqfilter(fp->f_devunit, kn);
}
static int
tap_dev_kqfilter(int unit, struct knote *kn)
{
struct tap_softc *sc = device_lookup_private(&tap_cd, unit);
if (sc == NULL)
return ENXIO;
KERNEL_LOCK(1, NULL);
switch(kn->kn_filter) {
case EVFILT_READ:
kn->kn_fop = &tap_read_filterops;
break;
case EVFILT_WRITE:
kn->kn_fop = &tap_seltrue_filterops;
break;
default:
KERNEL_UNLOCK_ONE(NULL);
return EINVAL;
}
kn->kn_hook = sc;
mutex_spin_enter(&sc->sc_lock);
SLIST_INSERT_HEAD(&sc->sc_rsel.sel_klist, kn, kn_selnext);
mutex_spin_exit(&sc->sc_lock);
KERNEL_UNLOCK_ONE(NULL);
return 0;
}
static void
tap_kqdetach(struct knote *kn)
{
struct tap_softc *sc = (struct tap_softc *)kn->kn_hook;
KERNEL_LOCK(1, NULL);
mutex_spin_enter(&sc->sc_lock);
SLIST_REMOVE(&sc->sc_rsel.sel_klist, kn, knote, kn_selnext);
mutex_spin_exit(&sc->sc_lock);
KERNEL_UNLOCK_ONE(NULL);
}
static int
tap_kqread(struct knote *kn, long hint)
{
struct tap_softc *sc = (struct tap_softc *)kn->kn_hook;
struct ifnet *ifp = &sc->sc_ec.ec_if;
struct mbuf *m;
int s, rv;
KERNEL_LOCK(1, NULL);
s = splnet();
IFQ_POLL(&ifp->if_snd, m);
if (m == NULL)
kn->kn_data = 0;
else
kn->kn_data = m->m_pkthdr.len;
splx(s);
rv = (kn->kn_data != 0 ? 1 : 0);
KERNEL_UNLOCK_ONE(NULL);
return rv;
}
/*
* sysctl management routines
* You can set the address of an interface through:
* net.link.tap.tap<number>
*
* Note the consistent use of tap_log in order to use
* sysctl_teardown at unload time.
*
* In the kernel you will find a lot of SYSCTL_SETUP blocks. Those
* blocks register a function in a special section of the kernel
* (called a link set) which is used at init_sysctl() time to cycle
* through all those functions to create the kernel's sysctl tree.
*
* It is not possible to use link sets in a module, so the
* easiest is to simply call our own setup routine at load time.
*
* In the SYSCTL_SETUP blocks you find in the kernel, nodes have the
* CTLFLAG_PERMANENT flag, meaning they cannot be removed. Once the
* whole kernel sysctl tree is built, it is not possible to add any
* permanent node.
*
* It should be noted that we're not saving the sysctlnode pointer
* we are returned when creating the "tap" node. That structure
* cannot be trusted once out of the calling function, as it might
* get reused. So we just save the MIB number, and always give the
* full path starting from the root for later calls to sysctl_createv
* and sysctl_destroyv.
*/
static void
sysctl_tap_setup(struct sysctllog **clog)
{
const struct sysctlnode *node;
int error = 0;
if ((error = sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "link", NULL,
NULL, 0, NULL, 0,
CTL_NET, AF_LINK, CTL_EOL)) != 0)
return;
/*
* The first four parameters of sysctl_createv are for management.
*
* The four that follows, here starting with a '0' for the flags,
* describe the node.
*
* The next series of four set its value, through various possible
* means.
*
* Last but not least, the path to the node is described. That path
* is relative to the given root (third argument). Here we're
* starting from the root.
*/
if ((error = sysctl_createv(clog, 0, NULL, &node,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "tap", NULL,
NULL, 0, NULL, 0,
CTL_NET, AF_LINK, CTL_CREATE, CTL_EOL)) != 0)
return;
tap_node = node->sysctl_num;
}
/*
* The helper functions make Andrew Brown's interface really
* shine. It makes possible to create value on the fly whether
* the sysctl value is read or written.
*
* As shown as an example in the man page, the first step is to
* create a copy of the node to have sysctl_lookup work on it.
*
* Here, we have more work to do than just a copy, since we have
* to create the string. The first step is to collect the actual
* value of the node, which is a convenient pointer to the softc
* of the interface. From there we create the string and use it
* as the value, but only for the *copy* of the node.
*
* Then we let sysctl_lookup do the magic, which consists in
* setting oldp and newp as required by the operation. When the
* value is read, that means that the string will be copied to
* the user, and when it is written, the new value will be copied
* over in the addr array.
*
* If newp is NULL, the user was reading the value, so we don't
* have anything else to do. If a new value was written, we
* have to check it.
*
* If it is incorrect, we can return an error and leave 'node' as
* it is: since it is a copy of the actual node, the change will
* be forgotten.
*
* Upon a correct input, we commit the change to the ifnet
* structure of our interface.
*/
static int
tap_sysctl_handler(SYSCTLFN_ARGS)
{
struct sysctlnode node;
struct tap_softc *sc;
struct ifnet *ifp;
int error;
size_t len;
char addr[3 * ETHER_ADDR_LEN];
uint8_t enaddr[ETHER_ADDR_LEN];
node = *rnode;
sc = node.sysctl_data;
ifp = &sc->sc_ec.ec_if;
(void)ether_snprintf(addr, sizeof(addr), CLLADDR(ifp->if_sadl));
node.sysctl_data = addr;
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (error || newp == NULL)
return error;
len = strlen(addr);
if (len < 11 || len > 17)
return EINVAL;
/* Commit change */
if (ether_aton_r(enaddr, sizeof(enaddr), addr) != 0)
return EINVAL;
if_set_sadl(ifp, enaddr, ETHER_ADDR_LEN, false);
return error;
}
/*
* Module infrastructure
*/
#include "if_module.h"
IF_MODULE(MODULE_CLASS_DRIVER, tap, NULL)