/* $NetBSD: if_tap.c,v 1.136 2024/11/10 10:57:52 mlelstv 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 __KERNEL_RCSID(0, "$NetBSD: if_tap.c,v 1.136 2024/11/10 10:57:52 mlelstv Exp $"); #if defined(_KERNEL_OPT) #include "opt_modular.h" #include "opt_net_mpsafe.h" #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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 **); 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); 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 void 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 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); static void 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; #ifdef _MODULE devsw_attach("tap", NULL, &tap_bmajor, &tap_cdevsw, &tap_cmajor); #endif 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); } static int tapdetach(void) { int error = 0; if_clone_detach(&tap_cloners); if (tap_count != 0) { if_clone_attach(&tap_cloners); return EBUSY; } error = config_cfattach_detach(tap_cd.cd_name, &tap_ca); if (error == 0) { #ifdef _MODULE devsw_detach(NULL, &tap_cdevsw); #endif sysctl_teardown(&tap_sysctl_clog); } else 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)); /* * 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; #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. */ 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. 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); 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; if_statadd2(ifp, if_opackets, 1, if_obytes, m0->m_len); 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 ether_ioctl() has 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 * 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; 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)); } static int tap_clone_destroy(struct ifnet *ifp) { struct tap_softc *sc = ifp->if_softc; tap_clone_destroyer(sc->sc_dev); atomic_dec_uint(&tap_count); return 0; } static void tap_clone_destroyer(device_t dev) { cfdata_t cf = device_cfdata(dev); int error; error = config_detach(dev, DETACH_FORCE); KASSERTMSG(error == 0, "error=%d", error); kmem_free(cf, sizeof(*cf)); } /* * 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; if ((sc = tap_clone_creator(-1)) == NULL) { fd_abort(curproc, fp, fd); return ENXIO; } sc->sc_flags |= TAP_INUSE; if_link_state_change(&sc->sc_ec.ec_if, LINK_STATE_UP); 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; 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); out: KERNEL_UNLOCK_ONE(NULL); return 0; } static void 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; if_statadd2(ifp, if_opackets, 1, if_obytes, m->m_len); 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); if_link_state_change(ifp, LINK_STATE_DOWN); } 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; 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; } if_statadd2(ifp, if_opackets, 1, if_obytes, m->m_len); /* XXX only first in chain */ bpf_mtap(ifp, m, BPF_D_OUT); if ((error = pfil_run_hooks(ifp->if_pfil, &m, ifp, PFIL_OUT)) != 0) goto out; if (m == NULL) goto 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); 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; size_t len = 0; 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) { if_statinc(ifp, if_ierrors); return ENOBUFS; } MCLAIM(m, &sc->sc_ec.ec_rx_mowner); 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; } MCLAIM(*mp, &sc->sc_ec.ec_rx_mowner); } (*mp)->m_len = uimin(MHLEN, uio->uio_resid); len += (*mp)->m_len; error = uiomove(mtod(*mp, void *), (*mp)->m_len, uio); mp = &(*mp)->m_next; } if (error) { if_statinc(ifp, if_ierrors); m_freem(m); return error; } m_set_rcvif(m, ifp); if_statadd2(ifp, if_ipackets, 1, if_ibytes, len); bpf_mtap(ifp, m, BPF_D_IN); if ((error = pfil_run_hooks(ifp->if_pfil, &m, ifp, PFIL_IN)) != 0) return error; if (m == NULL) return 0; 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 = { .f_flags = FILTEROP_ISFD, .f_attach = NULL, .f_detach = tap_kqdetach, .f_event = tap_kqread, }; 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; switch(kn->kn_filter) { case EVFILT_READ: kn->kn_fop = &tap_read_filterops; kn->kn_hook = sc; KERNEL_LOCK(1, NULL); mutex_spin_enter(&sc->sc_lock); selrecord_knote(&sc->sc_rsel, kn); mutex_spin_exit(&sc->sc_lock); KERNEL_UNLOCK_ONE(NULL); break; case EVFILT_WRITE: kn->kn_fop = &seltrue_filtops; break; default: return EINVAL; } 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); selremove_knote(&sc->sc_rsel, kn); 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 * * 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)