/* $NetBSD: if_tap.c,v 1.19 2006/07/23 22:06:12 ad Exp $ */ /* * Copyright (c) 2003, 2004 The NetBSD Foundation. * All rights reserved. * * This code is derived from software contributed to the NetBSD Foundation * by Quentin Garnier. * * 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation 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 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 __KERNEL_RCSID(0, "$NetBSD: if_tap.c,v 1.19 2006/07/23 22:06:12 ad Exp $"); #if defined(_KERNEL_OPT) #include "bpfilter.h" #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if NBPFILTER > 0 #include #endif /* * sysctl node management * * It's not really possible to use a SYSCTL_SETUP block with * current LKM 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); SYSCTL_SETUP_PROTO(sysctl_tap_setup); /* * Since we're an Ethernet device, we need the 3 following * components: a leading struct device, a struct ethercom, * and also 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 { struct device 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 */ struct lock sc_rdlock; struct simplelock sc_kqlock; }; /* autoconf(9) glue */ void tapattach(int); static int tap_match(struct device *, struct cfdata *, void *); static void tap_attach(struct device *, struct device *, void *); static int tap_detach(struct device*, int); /* Ethernet address helper functions */ static int tap_ether_aton(u_char *, char *); CFATTACH_DECL(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, caddr_t, 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(struct file *, struct lwp *); static int tap_fops_read(struct file *, off_t *, struct uio *, kauth_cred_t, int); static int tap_fops_write(struct file *, off_t *, struct uio *, kauth_cred_t, int); static int tap_fops_ioctl(struct file *, u_long, void *, struct lwp *); static int tap_fops_poll(struct file *, int, struct lwp *); static int tap_fops_kqfilter(struct file *, struct knote *); static const struct fileops tap_fileops = { tap_fops_read, tap_fops_write, tap_fops_ioctl, fnullop_fcntl, tap_fops_poll, fbadop_stat, tap_fops_close, tap_fops_kqfilter, }; /* 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, caddr_t, 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 = { tap_cdev_open, tap_cdev_close, tap_cdev_read, tap_cdev_write, tap_cdev_ioctl, nostop, notty, tap_cdev_poll, nommap, tap_cdev_kqfilter, }; #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, caddr_t); /* This is an internal function to keep tap_ioctl readable */ static int tap_lifaddr(struct ifnet *, u_long, struct ifaliasreq *); /* * 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 functionis shared by the two cloning code paths */ static struct tap_softc * tap_clone_creator(int); int tap_clone_destroyer(struct device *); void tapattach(int n) { int error; 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); } /* Pretty much useless for a pseudo-device */ static int tap_match(struct device *self, struct cfdata *cfdata, void *arg) { return (1); } void tap_attach(struct device *parent, struct device *self, void *aux) { struct tap_softc *sc = (struct tap_softc *)self; struct ifnet *ifp; const struct sysctlnode *node; u_int8_t enaddr[ETHER_ADDR_LEN] = { 0xf2, 0x0b, 0xa4, 0xff, 0xff, 0xff }; char enaddrstr[3 * ETHER_ADDR_LEN]; struct timeval tv; uint32_t ui; int error; aprint_normal("%s: faking Ethernet device\n", self->dv_xname); /* * In order to obtain unique initial Ethernet address on a host, * do some randomisation using the current uptime. It's not meant * for anything but avoiding hard-coding an address. */ getmicrouptime(&tv); ui = (tv.tv_sec ^ tv.tv_usec) & 0xffffff; memcpy(enaddr+3, (u_int8_t *)&ui, 3); aprint_normal("%s: Ethernet address %s\n", sc->sc_dev.dv_xname, 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. */ 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, sc->sc_dev.dv_xname); ifp->if_softc = sc; ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST; 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, the fisrt call * being common to all network interface drivers. */ if_attach(ifp); ether_ifattach(ifp, enaddr); sc->sc_flags = 0; /* * 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. */ if ((error = sysctl_createv(NULL, 0, NULL, &node, CTLFLAG_READWRITE, CTLTYPE_STRING, sc->sc_dev.dv_xname, NULL, tap_sysctl_handler, 0, sc, 18, CTL_NET, AF_LINK, tap_node, device_unit(&sc->sc_dev), CTL_EOL)) != 0) aprint_error("%s: sysctl_createv returned %d, ignoring\n", sc->sc_dev.dv_xname, error); /* * Initialize the two locks for the device. * * We need a lock here because even though the tap device can be * opened only once, the file descriptor might be passed to another * process, say a fork(2)ed child. * * The Giant saves us from most of the hassle, but since the read * operation can sleep, we don't want two processes to wake up at * the same moment and both try and dequeue a single packet. * * The queue for event listeners (used by kqueue(9), see below) has * to be protected, too, but we don't need the same level of * complexity for that lock, so a simple spinning lock is fine. */ lockinit(&sc->sc_rdlock, PSOCK|PCATCH, "tapl", 0, LK_SLEEPFAIL); simple_lock_init(&sc->sc_kqlock); } /* * When detaching, we do the inverse of what is done in the attach * routine, in reversed order. */ static int tap_detach(struct device* self, int flags) { struct tap_softc *sc = (struct tap_softc *)self; struct ifnet *ifp = &sc->sc_ec.ec_if; int error, s; /* * Some processes might be sleeping on "tap", so we have to make * them release their hold on the device. * * The LK_DRAIN operation will wait for every locked process to * release their hold. */ sc->sc_flags |= TAP_GOING; s = splnet(); tap_stop(ifp, 1); if_down(ifp); splx(s); lockmgr(&sc->sc_rdlock, LK_DRAIN, 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("%s: sysctl_destroyv returned %d, ignoring\n", sc->sc_dev.dv_xname, error); ether_ifdetach(ifp); if_detach(ifp); ifmedia_delete_instance(&sc->sc_im, IFM_INST_ANY); 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; if ((sc->sc_flags & TAP_INUSE) == 0) { /* Simply drop packets */ for(;;) { IFQ_DEQUEUE(&ifp->if_snd, m0); if (m0 == NULL) return; ifp->if_opackets++; #if NBPFILTER > 0 if (ifp->if_bpf) bpf_mtap(ifp->if_bpf, m0); #endif m_freem(m0); } } else if (!IFQ_IS_EMPTY(&ifp->if_snd)) { ifp->if_flags |= IFF_OACTIVE; wakeup(sc); selnotify(&sc->sc_rsel, 1); if (sc->sc_flags & TAP_ASYNCIO) fownsignal(sc->sc_pgid, SIGIO, POLL_IN, POLLIN|POLLRDNORM, 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, caddr_t data) { struct tap_softc *sc = (struct tap_softc *)ifp->if_softc; struct ifreq *ifr = (struct ifreq *)data; int s, error; s = splnet(); switch (cmd) { case SIOCSIFMEDIA: case SIOCGIFMEDIA: error = ifmedia_ioctl(ifp, ifr, &sc->sc_im, cmd); break; 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 shouldn't be done there, * and should actually be available to all Ethernet drivers, real or not. */ static int tap_lifaddr(struct ifnet *ifp, u_long cmd, struct ifaliasreq *ifra) { struct sockaddr *sa = (struct sockaddr *)&ifra->ifra_addr; if (sa->sa_family != AF_LINK) return (EINVAL); memcpy(LLADDR(ifp->if_sadl), sa->sa_data, ETHER_ADDR_LEN); 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; ifp->if_flags &= ~IFF_RUNNING; wakeup(sc); selnotify(&sc->sc_rsel, 1); if (sc->sc_flags & TAP_ASYNCIO) fownsignal(sc->sc_pgid, SIGIO, POLL_HUP, 0, NULL); } /* * 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); } 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. * * config_attach_pseudo can be called with unit = DVUNIT_ANY to have * autoconf(9) choose a unit number for us. This is what happens when * the cloner is openend, while the ifcloner interface creates a device * with a specific unit number. */ static struct tap_softc * tap_clone_creator(int unit) { struct cfdata *cf; cf = malloc(sizeof(*cf), M_DEVBUF, M_WAITOK); cf->cf_name = tap_cd.cd_name; cf->cf_atname = tap_ca.ca_name; cf->cf_unit = unit; cf->cf_fstate = FSTATE_STAR; return (struct tap_softc *)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) { return tap_clone_destroyer((struct device *)ifp->if_softc); } int tap_clone_destroyer(struct device *dev) { struct cfdata *cf = device_cfdata(dev); int error; if ((error = config_detach(dev, 0)) != 0) aprint_error("%s: unable to detach instance\n", dev->dv_xname); free(cf, M_DEVBUF); 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 = (struct tap_softc *)device_lookup(&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_data 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; struct file *fp; int error, fd; if ((error = falloc(l, &fp, &fd)) != 0) return (error); if ((sc = tap_clone_creator(DVUNIT_ANY)) == NULL) { FILE_UNUSE(fp, l); ffree(fp); return (ENXIO); } sc->sc_flags |= TAP_INUSE; return fdclone(l, 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 = (struct tap_softc *)device_lookup(&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(struct file *fp, struct lwp *l) { int unit = (intptr_t)fp->f_data; struct tap_softc *sc; int error; sc = (struct tap_softc *)device_lookup(&tap_cd, unit); if (sc == NULL) return (ENXIO); /* tap_dev_close currently always succeeds, but it might not * always be the case. */ if ((error = tap_dev_close(sc)) != 0) 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) return (0); return tap_clone_destroyer((struct device *)sc); } 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++; #if NBPFILTER > 0 if (ifp->if_bpf) bpf_mtap(ifp->if_bpf, m); #endif } } splx(s); 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(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred, int flags) { return tap_dev_read((intptr_t)fp->f_data, uio, flags); } static int tap_dev_read(int unit, struct uio *uio, int flags) { struct tap_softc *sc = (struct tap_softc *)device_lookup(&tap_cd, unit); struct ifnet *ifp; struct mbuf *m, *n; int error = 0, s; if (sc == NULL) return (ENXIO); 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) && lockstatus(&sc->sc_rdlock) == LK_EXCLUSIVE) return (EWOULDBLOCK); error = lockmgr(&sc->sc_rdlock, LK_EXCLUSIVE, NULL); if (error != 0) return (error); s = splnet(); if (IFQ_IS_EMPTY(&ifp->if_snd)) { ifp->if_flags &= ~IFF_OACTIVE; splx(s); /* * We must release the lock before sleeping, and re-acquire it * after. */ (void)lockmgr(&sc->sc_rdlock, LK_RELEASE, NULL); if (sc->sc_flags & TAP_NBIO) error = EWOULDBLOCK; else error = tsleep(sc, PSOCK|PCATCH, "tap", 0); if (error != 0) return (error); /* The device might have been downed */ if ((ifp->if_flags & IFF_UP) == 0) return (EHOSTDOWN); if ((sc->sc_flags & TAP_NBIO) && lockstatus(&sc->sc_rdlock) == LK_EXCLUSIVE) return (EWOULDBLOCK); error = lockmgr(&sc->sc_rdlock, LK_EXCLUSIVE, NULL); if (error != 0) return (error); s = splnet(); } IFQ_DEQUEUE(&ifp->if_snd, m); ifp->if_flags &= ~IFF_OACTIVE; splx(s); if (m == NULL) { error = 0; goto out; } ifp->if_opackets++; #if NBPFILTER > 0 if (ifp->if_bpf) bpf_mtap(ifp->if_bpf, m); #endif /* * One read is one packet. */ do { error = uiomove(mtod(m, caddr_t), min(m->m_len, uio->uio_resid), uio); MFREE(m, n); m = n; } while (m != NULL && uio->uio_resid > 0 && error == 0); if (m != NULL) m_freem(m); out: (void)lockmgr(&sc->sc_rdlock, LK_RELEASE, 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(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred, int flags) { return tap_dev_write((intptr_t)fp->f_data, uio, flags); } static int tap_dev_write(int unit, struct uio *uio, int flags) { struct tap_softc *sc = (struct tap_softc *)device_lookup(&tap_cd, unit); struct ifnet *ifp; struct mbuf *m, **mp; int error = 0; int s; if (sc == NULL) return (ENXIO); 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 = min(MHLEN, uio->uio_resid); error = uiomove(mtod(*mp, caddr_t), (*mp)->m_len, uio); mp = &(*mp)->m_next; } if (error) { ifp->if_ierrors++; m_freem(m); return (error); } ifp->if_ipackets++; m->m_pkthdr.rcvif = ifp; #if NBPFILTER > 0 if (ifp->if_bpf) bpf_mtap(ifp->if_bpf, m); #endif s =splnet(); (*ifp->if_input)(ifp, m); splx(s); return (0); } static int tap_cdev_ioctl(dev_t dev, u_long cmd, caddr_t data, int flags, struct lwp *l) { return tap_dev_ioctl(minor(dev), cmd, data, l); } static int tap_fops_ioctl(struct file *fp, u_long cmd, void *data, struct lwp *l) { return tap_dev_ioctl((intptr_t)fp->f_data, cmd, (caddr_t)data, l); } static int tap_dev_ioctl(int unit, u_long cmd, caddr_t data, struct lwp *l) { struct tap_softc *sc = (struct tap_softc *)device_lookup(&tap_cd, unit); int error = 0; 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); } break; case TIOCSPGRP: case FIOSETOWN: error = fsetown(l->l_proc, &sc->sc_pgid, cmd, data); break; case TIOCGPGRP: case FIOGETOWN: error = fgetown(l->l_proc, sc->sc_pgid, cmd, data); break; case FIOASYNC: if (*(int *)data) sc->sc_flags |= TAP_ASYNCIO; else sc->sc_flags &= ~TAP_ASYNCIO; break; case FIONBIO: if (*(int *)data) sc->sc_flags |= TAP_NBIO; else sc->sc_flags &= ~TAP_NBIO; break; case TAPGIFNAME: { struct ifreq *ifr = (struct ifreq *)data; struct ifnet *ifp = &sc->sc_ec.ec_if; strlcpy(ifr->ifr_name, ifp->if_xname, IFNAMSIZ); } break; default: error = ENOTTY; break; } return (0); } 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(struct file *fp, int events, struct lwp *l) { return tap_dev_poll((intptr_t)fp->f_data, events, l); } static int tap_dev_poll(int unit, int events, struct lwp *l) { struct tap_softc *sc = (struct tap_softc *)device_lookup(&tap_cd, unit); int revents = 0; if (sc == NULL) return (ENXIO); 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); splx(s); if (m != NULL) revents |= events & (POLLIN|POLLRDNORM); else { simple_lock(&sc->sc_kqlock); selrecord(l, &sc->sc_rsel); simple_unlock(&sc->sc_kqlock); } } 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(struct file *fp, struct knote *kn) { return tap_dev_kqfilter((intptr_t)fp->f_data, kn); } static int tap_dev_kqfilter(int unit, struct knote *kn) { struct tap_softc *sc = (struct tap_softc *)device_lookup(&tap_cd, unit); if (sc == NULL) return (ENXIO); 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: return (1); } kn->kn_hook = sc; simple_lock(&sc->sc_kqlock); SLIST_INSERT_HEAD(&sc->sc_rsel.sel_klist, kn, kn_selnext); simple_unlock(&sc->sc_kqlock); return (0); } static void tap_kqdetach(struct knote *kn) { struct tap_softc *sc = (struct tap_softc *)kn->kn_hook; simple_lock(&sc->sc_kqlock); SLIST_REMOVE(&sc->sc_rsel.sel_klist, kn, knote, kn_selnext); simple_unlock(&sc->sc_kqlock); } 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; 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); return (kn->kn_data != 0 ? 1 : 0); } /* * sysctl management routines * You can set the address of an interface through: * net.link.tap.tap * * 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 (currently) possible to use link sets in a LKM, 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. */ SYSCTL_SETUP(sysctl_tap_setup, "sysctl net.link.tap subtree setup") { const struct sysctlnode *node; int error = 0; if ((error = sysctl_createv(clog, 0, NULL, NULL, CTLFLAG_PERMANENT, CTLTYPE_NODE, "net", NULL, NULL, 0, NULL, 0, CTL_NET, CTL_EOL)) != 0) return; 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]; node = *rnode; sc = node.sysctl_data; ifp = &sc->sc_ec.ec_if; (void)ether_snprintf(addr, sizeof(addr), LLADDR(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 (tap_ether_aton(LLADDR(ifp->if_sadl), addr) != 0) return (EINVAL); return (error); } /* * ether_aton implementation, not using a static buffer. */ static int tap_ether_aton(u_char *dest, char *str) { int i; char *cp = str; u_char val[6]; #define set_value \ if (*cp > '9' && *cp < 'a') \ *cp -= 'A' - 10; \ else if (*cp > '9') \ *cp -= 'a' - 10; \ else \ *cp -= '0' for (i = 0; i < 6; i++, cp++) { if (!isxdigit(*cp)) return (1); set_value; val[i] = *cp++; if (isxdigit(*cp)) { set_value; val[i] *= 16; val[i] += *cp++; } if (*cp == ':' || i == 5) continue; else return (1); } memcpy(dest, val, 6); return (0); }