/*
* 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.
*/
/*
* 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 **);
struct tap_softc {
device_t sc_dev;
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);
/*
* 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 *);
/*
* 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 *);
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);
/* Those steps are mandatory for an Ethernet driver. */
if_initialize(ifp);
ifp->if_percpuq = if_percpuq_create(ifp);
ether_ifattach(ifp, enaddr);
/* Opening the device will bring the link state up. */
ifp->if_link_state = LINK_STATE_DOWN;
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;
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);
seldestroy(&sc->sc_rsel);
mutex_destroy(&sc->sc_lock);
cv_destroy(&sc->sc_cv);
pmf_device_deregister(self);
return 0;
}
/*
* 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;
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 ether_ioctl() has to be called under splnet().
*/
static int
tap_ioctl(struct ifnet *ifp, u_long cmd, void *data)
{
int s, 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;
/*
* _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
* responsibility 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;
/*
* 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;
}
/*
* 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.
*
* A 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;
if_link_state_change(&sc->sc_ec.ec_if, LINK_STATE_UP);
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;
/*
* 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;
tap_dev_close(sc);
return 0;
}
/*
* 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;
sc = device_lookup_private(&tap_cd, unit);
if (sc == NULL)
return ENXIO;
KERNEL_LOCK(1, NULL);
tap_dev_close(sc);
/*
* Destroy the device now that it is no longer useful, unless
* it's already being destroyed.
*/
if ((sc->sc_flags & TAP_GOING) != 0)
goto out;
tap_clone_destroyer(sc->sc_dev);
/*
* 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;
/*
* 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];
