/*- * SPDX-License-Identifier: BSD-2-Clause * * Copyright (c) 2008 The FreeBSD Foundation * Copyright (c) 2009-2021 Bjoern A. Zeeb * * This software was developed by CK Software GmbH under sponsorship * from the FreeBSD Foundation. * * 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 AUTHOR 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 AUTHOR 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. */ /* * A pair of virtual back-to-back connected ethernet like interfaces * (``two interfaces with a virtual cross-over cable''). * * This is mostly intended to be used to provide connectivity between * different virtual network stack instances. */ #include #include "opt_rss.h" #include "opt_inet.h" #include "opt_inet6.h" #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 #ifdef RSS #include #ifdef INET #include #endif #ifdef INET6 #include #endif #endif #include static const char epairname[] = "epair"; #define RXRSIZE 4096 /* Probably overkill by 4-8x. */ static MALLOC_DEFINE(M_EPAIR, epairname, "Pair of virtual cross-over connected Ethernet-like interfaces"); VNET_DEFINE_STATIC(struct if_clone *, epair_cloner); #define V_epair_cloner VNET(epair_cloner) static unsigned int next_index = 0; #define EPAIR_LOCK_INIT() mtx_init(&epair_n_index_mtx, "epairidx", \ NULL, MTX_DEF) #define EPAIR_LOCK_DESTROY() mtx_destroy(&epair_n_index_mtx) #define EPAIR_LOCK() mtx_lock(&epair_n_index_mtx) #define EPAIR_UNLOCK() mtx_unlock(&epair_n_index_mtx) struct epair_softc; struct epair_queue { struct mtx mtx; struct mbufq q; int id; enum { EPAIR_QUEUE_IDLE, EPAIR_QUEUE_WAKING, EPAIR_QUEUE_RUNNING, } state; struct task tx_task; struct epair_softc *sc; }; static struct mtx epair_n_index_mtx; struct epair_softc { struct ifnet *ifp; /* This ifp. */ struct ifnet *oifp; /* other ifp of pair. */ int num_queues; struct epair_queue *queues; struct ifmedia media; /* Media config (fake). */ STAILQ_ENTRY(epair_softc) entry; }; struct epair_tasks_t { int tasks; struct taskqueue *tq[MAXCPU]; }; static struct epair_tasks_t epair_tasks; static void epair_clear_mbuf(struct mbuf *m) { M_ASSERTPKTHDR(m); /* Remove any CSUM_SND_TAG as ether_input will barf. */ if (m->m_pkthdr.csum_flags & CSUM_SND_TAG) { m_snd_tag_rele(m->m_pkthdr.snd_tag); m->m_pkthdr.snd_tag = NULL; m->m_pkthdr.csum_flags &= ~CSUM_SND_TAG; } /* Clear vlan information. */ m->m_flags &= ~M_VLANTAG; m->m_pkthdr.ether_vtag = 0; m_tag_delete_nonpersistent(m); } static void epair_tx_start_deferred(void *arg, int pending) { struct epair_queue *q = (struct epair_queue *)arg; if_t ifp; struct mbuf *m, *n; bool resched; ifp = q->sc->ifp; if_ref(ifp); CURVNET_SET(ifp->if_vnet); mtx_lock(&q->mtx); m = mbufq_flush(&q->q); q->state = EPAIR_QUEUE_RUNNING; mtx_unlock(&q->mtx); while (m != NULL) { n = STAILQ_NEXT(m, m_stailqpkt); m->m_nextpkt = NULL; if_input(ifp, m); m = n; } /* * Avoid flushing the queue more than once per task. We can otherwise * end up starving ourselves in a multi-epair routing configuration. */ mtx_lock(&q->mtx); if (!mbufq_empty(&q->q)) { resched = true; q->state = EPAIR_QUEUE_WAKING; } else { resched = false; q->state = EPAIR_QUEUE_IDLE; } mtx_unlock(&q->mtx); if (resched) taskqueue_enqueue(epair_tasks.tq[q->id], &q->tx_task); CURVNET_RESTORE(); if_rele(ifp); } static struct epair_queue * epair_select_queue(struct epair_softc *sc, struct mbuf *m) { uint32_t bucket; #ifdef RSS struct ether_header *eh; int ret; ret = rss_m2bucket(m, &bucket); if (ret) { /* Actually hash the packet. */ eh = mtod(m, struct ether_header *); switch (ntohs(eh->ether_type)) { #ifdef INET case ETHERTYPE_IP: rss_soft_m2cpuid_v4(m, 0, &bucket); break; #endif #ifdef INET6 case ETHERTYPE_IPV6: rss_soft_m2cpuid_v6(m, 0, &bucket); break; #endif default: bucket = 0; break; } } bucket %= sc->num_queues; #else bucket = 0; #endif return (&sc->queues[bucket]); } static void epair_prepare_mbuf(struct mbuf *m, struct ifnet *src_ifp) { M_ASSERTPKTHDR(m); epair_clear_mbuf(m); if_setrcvif(m, src_ifp); M_SETFIB(m, src_ifp->if_fib); MPASS(m->m_nextpkt == NULL); MPASS((m->m_pkthdr.csum_flags & CSUM_SND_TAG) == 0); } static void epair_menq(struct mbuf *m, struct epair_softc *osc) { struct epair_queue *q; struct ifnet *ifp, *oifp; int error, len; bool mcast; /* * I know this looks weird. We pass the "other sc" as we need that one * and can get both ifps from it as well. */ oifp = osc->ifp; ifp = osc->oifp; epair_prepare_mbuf(m, oifp); /* Save values as once the mbuf is queued, it's not ours anymore. */ len = m->m_pkthdr.len; mcast = (m->m_flags & (M_BCAST | M_MCAST)) != 0; q = epair_select_queue(osc, m); mtx_lock(&q->mtx); if (q->state == EPAIR_QUEUE_IDLE) { q->state = EPAIR_QUEUE_WAKING; taskqueue_enqueue(epair_tasks.tq[q->id], &q->tx_task); } error = mbufq_enqueue(&q->q, m); mtx_unlock(&q->mtx); if (error != 0) { m_freem(m); if_inc_counter(ifp, IFCOUNTER_OQDROPS, 1); } else { if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1); if_inc_counter(ifp, IFCOUNTER_OBYTES, len); if (mcast) if_inc_counter(ifp, IFCOUNTER_OMCASTS, 1); if_inc_counter(oifp, IFCOUNTER_IPACKETS, 1); } } static void epair_start(struct ifnet *ifp) { struct mbuf *m; struct epair_softc *sc; struct ifnet *oifp; /* * We get packets here from ether_output via if_handoff() * and need to put them into the input queue of the oifp * and will put the packet into the receive-queue (rxq) of the * other interface (oifp) of our pair. */ sc = ifp->if_softc; oifp = sc->oifp; sc = oifp->if_softc; for (;;) { IFQ_DEQUEUE(&ifp->if_snd, m); if (m == NULL) break; M_ASSERTPKTHDR(m); BPF_MTAP(ifp, m); /* In case either interface is not usable drop the packet. */ if ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0 || (ifp->if_flags & IFF_UP) == 0 || (oifp->if_drv_flags & IFF_DRV_RUNNING) == 0 || (oifp->if_flags & IFF_UP) == 0) { m_freem(m); continue; } epair_menq(m, sc); } } static int epair_transmit(struct ifnet *ifp, struct mbuf *m) { struct epair_softc *sc; struct ifnet *oifp; #ifdef ALTQ int len; bool mcast; #endif if (m == NULL) return (0); M_ASSERTPKTHDR(m); /* * We could just transmit this, but it makes testing easier if we're a * little bit more like real hardware. * Allow just that little bit extra for ethernet (and vlan) headers. */ if (m->m_pkthdr.len > (ifp->if_mtu + sizeof(struct ether_vlan_header))) { m_freem(m); if_inc_counter(ifp, IFCOUNTER_OERRORS, 1); return (E2BIG); } /* * We are not going to use the interface en/dequeue mechanism * on the TX side. We are called from ether_output_frame() * and will put the packet into the receive-queue (rxq) of the * other interface (oifp) of our pair. */ if ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0) { m_freem(m); if_inc_counter(ifp, IFCOUNTER_OERRORS, 1); return (ENXIO); } if ((ifp->if_flags & IFF_UP) == 0) { m_freem(m); if_inc_counter(ifp, IFCOUNTER_OERRORS, 1); return (ENETDOWN); } BPF_MTAP(ifp, m); /* * In case the outgoing interface is not usable, * drop the packet. */ sc = ifp->if_softc; oifp = sc->oifp; if ((oifp->if_drv_flags & IFF_DRV_RUNNING) == 0 || (oifp->if_flags & IFF_UP) == 0) { if_inc_counter(ifp, IFCOUNTER_OERRORS, 1); m_freem(m); return (0); } #ifdef ALTQ len = m->m_pkthdr.len; mcast = (m->m_flags & (M_BCAST | M_MCAST)) != 0; int error = 0; /* Support ALTQ via the classic if_start() path. */ IF_LOCK(&ifp->if_snd); if (ALTQ_IS_ENABLED(&ifp->if_snd)) { ALTQ_ENQUEUE(&ifp->if_snd, m, NULL, error); if (error) if_inc_counter(ifp, IFCOUNTER_OQDROPS, 1); IF_UNLOCK(&ifp->if_snd); if (!error) { if_inc_counter(ifp, IFCOUNTER_OBYTES, len); if (mcast) if_inc_counter(ifp, IFCOUNTER_OMCASTS, 1); epair_start(ifp); } return (error); } IF_UNLOCK(&ifp->if_snd); #endif epair_menq(m, oifp->if_softc); return (0); } static void epair_qflush(struct ifnet *ifp __unused) { } static int epair_media_change(struct ifnet *ifp __unused) { /* Do nothing. */ return (0); } static void epair_media_status(struct ifnet *ifp __unused, struct ifmediareq *imr) { imr->ifm_status = IFM_AVALID | IFM_ACTIVE; imr->ifm_active = IFM_ETHER | IFM_10G_T | IFM_FDX; } static int epair_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) { struct epair_softc *sc; struct ifreq *ifr; int error; ifr = (struct ifreq *)data; switch (cmd) { case SIOCSIFFLAGS: case SIOCADDMULTI: case SIOCDELMULTI: error = 0; break; case SIOCSIFMEDIA: case SIOCGIFMEDIA: sc = ifp->if_softc; error = ifmedia_ioctl(ifp, ifr, &sc->media, cmd); break; case SIOCSIFMTU: /* We basically allow all kinds of MTUs. */ ifp->if_mtu = ifr->ifr_mtu; error = 0; break; default: /* Let the common ethernet handler process this. */ error = ether_ioctl(ifp, cmd, data); break; } return (error); } static void epair_init(void *dummy __unused) { } /* * Interface cloning functions. * We use our private ones so that we can create/destroy our secondary * device along with the primary one. */ static int epair_clone_match(struct if_clone *ifc, const char *name) { const char *cp; /* * Our base name is epair. * Our interfaces will be named epair[ab]. * So accept anything of the following list: * - epair * - epair * but not the epair[ab] versions. */ if (strncmp(epairname, name, sizeof(epairname)-1) != 0) return (0); for (cp = name + sizeof(epairname) - 1; *cp != '\0'; cp++) { if (*cp < '0' || *cp > '9') return (0); } return (1); } static void epair_clone_add(struct if_clone *ifc, struct epair_softc *scb) { struct ifnet *ifp; uint8_t eaddr[ETHER_ADDR_LEN]; /* 00:00:00:00:00:00 */ ifp = scb->ifp; /* Copy epairNa etheraddr and change the last byte. */ memcpy(eaddr, scb->oifp->if_hw_addr, ETHER_ADDR_LEN); eaddr[5] = 0x0b; ether_ifattach(ifp, eaddr); if_clone_addif(ifc, ifp); } static struct epair_softc * epair_alloc_sc(struct if_clone *ifc) { struct epair_softc *sc; struct ifnet *ifp = if_alloc(IFT_ETHER); if (ifp == NULL) return (NULL); sc = malloc(sizeof(struct epair_softc), M_EPAIR, M_WAITOK | M_ZERO); sc->ifp = ifp; sc->num_queues = epair_tasks.tasks; sc->queues = mallocarray(sc->num_queues, sizeof(struct epair_queue), M_EPAIR, M_WAITOK); for (int i = 0; i < sc->num_queues; i++) { struct epair_queue *q = &sc->queues[i]; q->id = i; q->state = EPAIR_QUEUE_IDLE; mtx_init(&q->mtx, "epairq", NULL, MTX_DEF | MTX_NEW); mbufq_init(&q->q, RXRSIZE); q->sc = sc; NET_TASK_INIT(&q->tx_task, 0, epair_tx_start_deferred, q); } /* Initialise pseudo media types. */ ifmedia_init(&sc->media, 0, epair_media_change, epair_media_status); ifmedia_add(&sc->media, IFM_ETHER | IFM_10G_T, 0, NULL); ifmedia_set(&sc->media, IFM_ETHER | IFM_10G_T); return (sc); } static void epair_setup_ifp(struct epair_softc *sc, char *name, int unit) { struct ifnet *ifp = sc->ifp; ifp->if_softc = sc; strlcpy(ifp->if_xname, name, IFNAMSIZ); ifp->if_dname = epairname; ifp->if_dunit = unit; ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST; ifp->if_capabilities = IFCAP_VLAN_MTU; ifp->if_capenable = IFCAP_VLAN_MTU; ifp->if_transmit = epair_transmit; ifp->if_qflush = epair_qflush; ifp->if_start = epair_start; ifp->if_ioctl = epair_ioctl; ifp->if_init = epair_init; if_setsendqlen(ifp, ifqmaxlen); if_setsendqready(ifp); ifp->if_baudrate = IF_Gbps(10); /* arbitrary maximum */ } static void epair_generate_mac(struct epair_softc *sc, uint8_t *eaddr) { uint32_t key[3]; uint32_t hash; uint64_t hostid; EPAIR_LOCK(); #ifdef SMP /* Get an approximate distribution. */ hash = next_index % mp_ncpus; #else hash = 0; #endif EPAIR_UNLOCK(); /* * Calculate the etheraddr hashing the hostid and the * interface index. The result would be hopefully unique. * Note that the "a" component of an epair instance may get moved * to a different VNET after creation. In that case its index * will be freed and the index can get reused by new epair instance. * Make sure we do not create same etheraddr again. */ getcredhostid(curthread->td_ucred, (unsigned long *)&hostid); if (hostid == 0) arc4rand(&hostid, sizeof(hostid), 0); struct ifnet *ifp = sc->ifp; EPAIR_LOCK(); if (ifp->if_index > next_index) next_index = ifp->if_index; else next_index++; key[0] = (uint32_t)next_index; EPAIR_UNLOCK(); key[1] = (uint32_t)(hostid & 0xffffffff); key[2] = (uint32_t)((hostid >> 32) & 0xfffffffff); hash = jenkins_hash32(key, 3, 0); eaddr[0] = 0x02; memcpy(&eaddr[1], &hash, 4); eaddr[5] = 0x0a; } static void epair_free_sc(struct epair_softc *sc) { if (sc == NULL) return; if_free(sc->ifp); ifmedia_removeall(&sc->media); for (int i = 0; i < sc->num_queues; i++) { struct epair_queue *q = &sc->queues[i]; mtx_destroy(&q->mtx); } free(sc->queues, M_EPAIR); free(sc, M_EPAIR); } static void epair_set_state(struct ifnet *ifp, bool running) { if (running) { ifp->if_drv_flags |= IFF_DRV_RUNNING; if_link_state_change(ifp, LINK_STATE_UP); } else { if_link_state_change(ifp, LINK_STATE_DOWN); ifp->if_drv_flags &= ~IFF_DRV_RUNNING; } } static int epair_handle_unit(struct if_clone *ifc, char *name, size_t len, int *punit) { int error = 0, unit, wildcard; char *dp; /* Try to see if a special unit was requested. */ error = ifc_name2unit(name, &unit); if (error != 0) return (error); wildcard = (unit < 0); error = ifc_alloc_unit(ifc, &unit); if (error != 0) return (error); /* * If no unit had been given, we need to adjust the ifName. * Also make sure there is space for our extra [ab] suffix. */ for (dp = name; *dp != '\0'; dp++); if (wildcard) { int slen = snprintf(dp, len - (dp - name), "%d", unit); if (slen > len - (dp - name) - 1) { /* ifName too long. */ error = ENOSPC; goto done; } dp += slen; } if (len - (dp - name) - 1 < 1) { /* No space left for our [ab] suffix. */ error = ENOSPC; goto done; } *dp = 'b'; /* Must not change dp so we can replace 'a' by 'b' later. */ *(dp+1) = '\0'; /* Check if 'a' and 'b' interfaces already exist. */ if (ifunit(name) != NULL) { error = EEXIST; goto done; } *dp = 'a'; if (ifunit(name) != NULL) { error = EEXIST; goto done; } *punit = unit; done: if (error != 0) ifc_free_unit(ifc, unit); return (error); } static int epair_clone_create(struct if_clone *ifc, char *name, size_t len, struct ifc_data *ifd, struct ifnet **ifpp) { struct epair_softc *sca, *scb; struct ifnet *ifp; char *dp; int error, unit; uint8_t eaddr[ETHER_ADDR_LEN]; /* 00:00:00:00:00:00 */ error = epair_handle_unit(ifc, name, len, &unit); if (error != 0) return (error); /* Allocate memory for both [ab] interfaces */ sca = epair_alloc_sc(ifc); scb = epair_alloc_sc(ifc); if (sca == NULL || scb == NULL) { epair_free_sc(sca); epair_free_sc(scb); ifc_free_unit(ifc, unit); return (ENOSPC); } /* * Cross-reference the interfaces so we will be able to free both. */ sca->oifp = scb->ifp; scb->oifp = sca->ifp; /* Finish initialization of interface a. */ ifp = sca->ifp; epair_setup_ifp(sca, name, unit); epair_generate_mac(sca, eaddr); ether_ifattach(ifp, eaddr); /* Swap the name and finish initialization of interface b. */ dp = name + strlen(name) - 1; *dp = 'b'; epair_setup_ifp(scb, name, unit); ifp = scb->ifp; /* We need to play some tricks here for the second interface. */ strlcpy(name, epairname, len); /* Correctly set the name for the cloner list. */ strlcpy(name, scb->ifp->if_xname, len); epair_clone_add(ifc, scb); /* * Restore name to a as the ifp for this will go into the * cloner list for the initial call. */ strlcpy(name, sca->ifp->if_xname, len); /* Tell the world, that we are ready to rock. */ epair_set_state(sca->ifp, true); epair_set_state(scb->ifp, true); *ifpp = sca->ifp; return (0); } static void epair_drain_rings(struct epair_softc *sc) { for (int i = 0; i < sc->num_queues; i++) { struct epair_queue *q; struct mbuf *m, *n; q = &sc->queues[i]; mtx_lock(&q->mtx); m = mbufq_flush(&q->q); mtx_unlock(&q->mtx); for (; m != NULL; m = n) { n = m->m_nextpkt; m_freem(m); } } } static int epair_clone_destroy(struct if_clone *ifc, struct ifnet *ifp, uint32_t flags) { struct ifnet *oifp; struct epair_softc *sca, *scb; int unit, error; /* * In case we called into if_clone_destroyif() ourselves * again to remove the second interface, the softc will be * NULL. In that case so not do anything but return success. */ if (ifp->if_softc == NULL) return (0); unit = ifp->if_dunit; sca = ifp->if_softc; oifp = sca->oifp; scb = oifp->if_softc; /* Frist get the interfaces down and detached. */ epair_set_state(ifp, false); epair_set_state(oifp, false); ether_ifdetach(ifp); ether_ifdetach(oifp); /* Third free any queued packets and all the resources. */ CURVNET_SET_QUIET(oifp->if_vnet); epair_drain_rings(scb); oifp->if_softc = NULL; error = if_clone_destroyif(ifc, oifp); if (error) panic("%s: if_clone_destroyif() for our 2nd iface failed: %d", __func__, error); epair_free_sc(scb); CURVNET_RESTORE(); epair_drain_rings(sca); epair_free_sc(sca); /* Last free the cloner unit. */ ifc_free_unit(ifc, unit); return (0); } static void vnet_epair_init(const void *unused __unused) { struct if_clone_addreq req = { .match_f = epair_clone_match, .create_f = epair_clone_create, .destroy_f = epair_clone_destroy, }; V_epair_cloner = ifc_attach_cloner(epairname, &req); } VNET_SYSINIT(vnet_epair_init, SI_SUB_PSEUDO, SI_ORDER_ANY, vnet_epair_init, NULL); static void vnet_epair_uninit(const void *unused __unused) { ifc_detach_cloner(V_epair_cloner); } VNET_SYSUNINIT(vnet_epair_uninit, SI_SUB_INIT_IF, SI_ORDER_ANY, vnet_epair_uninit, NULL); static int epair_mod_init(void) { char name[32]; epair_tasks.tasks = 0; #ifdef RSS int cpu; CPU_FOREACH(cpu) { cpuset_t cpu_mask; /* Pin to this CPU so we get appropriate NUMA allocations. */ thread_lock(curthread); sched_bind(curthread, cpu); thread_unlock(curthread); snprintf(name, sizeof(name), "epair_task_%d", cpu); epair_tasks.tq[cpu] = taskqueue_create(name, M_WAITOK, taskqueue_thread_enqueue, &epair_tasks.tq[cpu]); CPU_SETOF(cpu, &cpu_mask); taskqueue_start_threads_cpuset(&epair_tasks.tq[cpu], 1, PI_NET, &cpu_mask, "%s", name); epair_tasks.tasks++; } thread_lock(curthread); sched_unbind(curthread); thread_unlock(curthread); #else snprintf(name, sizeof(name), "epair_task"); epair_tasks.tq[0] = taskqueue_create(name, M_WAITOK, taskqueue_thread_enqueue, &epair_tasks.tq[0]); taskqueue_start_threads(&epair_tasks.tq[0], 1, PI_NET, "%s", name); epair_tasks.tasks = 1; #endif return (0); } static void epair_mod_cleanup(void) { for (int i = 0; i < epair_tasks.tasks; i++) { taskqueue_drain_all(epair_tasks.tq[i]); taskqueue_free(epair_tasks.tq[i]); } } static int epair_modevent(module_t mod, int type, void *data) { int ret; switch (type) { case MOD_LOAD: EPAIR_LOCK_INIT(); ret = epair_mod_init(); if (ret != 0) return (ret); if (bootverbose) printf("%s: %s initialized.\n", __func__, epairname); break; case MOD_UNLOAD: epair_mod_cleanup(); EPAIR_LOCK_DESTROY(); if (bootverbose) printf("%s: %s unloaded.\n", __func__, epairname); break; default: return (EOPNOTSUPP); } return (0); } static moduledata_t epair_mod = { "if_epair", epair_modevent, 0 }; DECLARE_MODULE(if_epair, epair_mod, SI_SUB_PSEUDO, SI_ORDER_MIDDLE); MODULE_VERSION(if_epair, 3);