/* $NetBSD: if_gif.c,v 1.42 2002/11/11 18:35:27 itojun Exp $ */ /* $KAME: if_gif.c,v 1.76 2001/08/20 02:01:02 kjc Exp $ */ /* * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. * 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. * 3. Neither the name of the project 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 PROJECT 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 PROJECT 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. */ #include __KERNEL_RCSID(0, "$NetBSD: if_gif.c,v 1.42 2002/11/11 18:35:27 itojun Exp $"); #include "opt_inet.h" #include "opt_iso.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET #include #include #endif /* INET */ #ifdef INET6 #ifndef INET #include #endif #include #include #include #include #include #endif /* INET6 */ #ifdef ISO #include #include #endif #include #include #include "bpfilter.h" #include void gifattach __P((int)); #ifndef __HAVE_GENERIC_SOFT_INTERRUPTS void gifnetisr __P((void)); #endif void gifintr __P((void *)); #ifdef ISO static struct mbuf *gif_eon_encap __P((struct mbuf *)); static struct mbuf *gif_eon_decap __P((struct ifnet *, struct mbuf *)); #endif /* * gif global variable definitions */ LIST_HEAD(, gif_softc) gif_softc_list; int gif_clone_create __P((struct if_clone *, int)); void gif_clone_destroy __P((struct ifnet *)); struct if_clone gif_cloner = IF_CLONE_INITIALIZER("gif", gif_clone_create, gif_clone_destroy); #ifndef MAX_GIF_NEST /* * This macro controls the upper limitation on nesting of gif tunnels. * Since, setting a large value to this macro with a careless configuration * may introduce system crash, we don't allow any nestings by default. * If you need to configure nested gif tunnels, you can define this macro * in your kernel configuration file. However, if you do so, please be * careful to configure the tunnels so that it won't make a loop. */ #define MAX_GIF_NEST 1 #endif static int max_gif_nesting = MAX_GIF_NEST; /* ARGSUSED */ void gifattach(count) int count; { LIST_INIT(&gif_softc_list); if_clone_attach(&gif_cloner); } int gif_clone_create(ifc, unit) struct if_clone *ifc; int unit; { struct gif_softc *sc; sc = malloc(sizeof(struct gif_softc), M_DEVBUF, M_WAIT); memset(sc, 0, sizeof(struct gif_softc)); sprintf(sc->gif_if.if_xname, "%s%d", ifc->ifc_name, unit); gifattach0(sc); LIST_INSERT_HEAD(&gif_softc_list, sc, gif_list); return (0); } void gifattach0(sc) struct gif_softc *sc; { sc->encap_cookie4 = sc->encap_cookie6 = NULL; sc->gif_if.if_addrlen = 0; sc->gif_if.if_mtu = GIF_MTU; sc->gif_if.if_flags = IFF_POINTOPOINT | IFF_MULTICAST; sc->gif_if.if_ioctl = gif_ioctl; sc->gif_if.if_output = gif_output; sc->gif_if.if_type = IFT_GIF; sc->gif_if.if_dlt = DLT_NULL; IFQ_SET_READY(&sc->gif_if.if_snd); if_attach(&sc->gif_if); if_alloc_sadl(&sc->gif_if); #if NBPFILTER > 0 bpfattach(&sc->gif_if, DLT_NULL, sizeof(u_int)); #endif } void gif_clone_destroy(ifp) struct ifnet *ifp; { struct gif_softc *sc = (void *) ifp; gif_delete_tunnel(&sc->gif_if); LIST_REMOVE(sc, gif_list); #ifdef INET6 encap_detach(sc->encap_cookie6); #endif #ifdef INET encap_detach(sc->encap_cookie4); #endif #if NBPFILTER > 0 bpfdetach(ifp); #endif if_detach(ifp); free(sc, M_DEVBUF); } #ifdef GIF_ENCAPCHECK int gif_encapcheck(m, off, proto, arg) const struct mbuf *m; int off; int proto; void *arg; { struct ip ip; struct gif_softc *sc; sc = (struct gif_softc *)arg; if (sc == NULL) return 0; if ((sc->gif_if.if_flags & IFF_UP) == 0) return 0; /* no physical address */ if (!sc->gif_psrc || !sc->gif_pdst) return 0; switch (proto) { #ifdef INET case IPPROTO_IPV4: break; #endif #ifdef INET6 case IPPROTO_IPV6: break; #endif #ifdef ISO case IPPROTO_EON: break; #endif default: return 0; } /* Bail on short packets */ KASSERT(m->m_flags & M_PKTHDR); if (m->m_pkthdr.len < sizeof(ip)) return 0; /* LINTED const cast */ m_copydata((struct mbuf *)m, 0, sizeof(ip), (caddr_t)&ip); switch (ip.ip_v) { #ifdef INET case 4: if (sc->gif_psrc->sa_family != AF_INET || sc->gif_pdst->sa_family != AF_INET) return 0; return gif_encapcheck4(m, off, proto, arg); #endif #ifdef INET6 case 6: if (m->m_pkthdr.len < sizeof(struct ip6_hdr)) return 0; if (sc->gif_psrc->sa_family != AF_INET6 || sc->gif_pdst->sa_family != AF_INET6) return 0; return gif_encapcheck6(m, off, proto, arg); #endif default: return 0; } } #endif int gif_output(ifp, m, dst, rt) struct ifnet *ifp; struct mbuf *m; struct sockaddr *dst; struct rtentry *rt; /* added in net2 */ { struct gif_softc *sc = (struct gif_softc*)ifp; int error = 0; static int called = 0; /* XXX: MUTEX */ ALTQ_DECL(struct altq_pktattr pktattr;) int s; IFQ_CLASSIFY(&ifp->if_snd, m, dst->sa_family, &pktattr); /* * gif may cause infinite recursion calls when misconfigured. * We'll prevent this by introducing upper limit. * XXX: this mechanism may introduce another problem about * mutual exclusion of the variable CALLED, especially if we * use kernel thread. */ if (++called > max_gif_nesting) { log(LOG_NOTICE, "gif_output: recursively called too many times(%d)\n", called); m_freem(m); error = EIO; /* is there better errno? */ goto end; } m->m_flags &= ~(M_BCAST|M_MCAST); if (!(ifp->if_flags & IFF_UP) || sc->gif_psrc == NULL || sc->gif_pdst == NULL) { m_freem(m); error = ENETDOWN; goto end; } /* inner AF-specific encapsulation */ switch (dst->sa_family) { #ifdef ISO case AF_ISO: m = gif_eon_encap(m); if (!m) { error = ENOBUFS; goto end; } break; #endif default: break; } /* XXX should we check if our outer source is legal? */ /* use DLT_NULL encapsulation here to pass inner af type */ M_PREPEND(m, sizeof(int), M_DONTWAIT); if (!m) { error = ENOBUFS; goto end; } *mtod(m, int *) = dst->sa_family; s = splnet(); IFQ_ENQUEUE(&ifp->if_snd, m, &pktattr, error); if (error) { splx(s); goto end; } splx(s); #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS softintr_schedule(sc->gif_si); #else /* XXX bad spl level? */ gifnetisr(); #endif error = 0; end: called = 0; /* reset recursion counter */ if (error) ifp->if_oerrors++; return error; } #ifndef __HAVE_GENERIC_SOFT_INTERRUPTS void gifnetisr() { struct gif_softc *sc; for (sc = LIST_FIRST(&gif_softc_list); sc != NULL; sc = LIST_NEXT(sc, gif_list)) { gifintr(sc); } } #endif void gifintr(arg) void *arg; { struct gif_softc *sc; struct ifnet *ifp; struct mbuf *m; int family; int len; int s; int error; sc = (struct gif_softc *)arg; ifp = &sc->gif_if; /* output processing */ while (1) { s = splnet(); IFQ_DEQUEUE(&sc->gif_if.if_snd, m); splx(s); if (m == NULL) break; /* grab and chop off inner af type */ if (sizeof(int) > m->m_len) { m = m_pullup(m, sizeof(int)); if (!m) { ifp->if_oerrors++; continue; } } family = *mtod(m, int *); #if NBPFILTER > 0 if (ifp->if_bpf) { #ifdef HAVE_OLD_BPF bpf_mtap(ifp, m); #else bpf_mtap(ifp->if_bpf, m); #endif } #endif m_adj(m, sizeof(int)); len = m->m_pkthdr.len; /* dispatch to output logic based on outer AF */ switch (sc->gif_psrc->sa_family) { #ifdef INET case AF_INET: error = in_gif_output(ifp, family, m); break; #endif #ifdef INET6 case AF_INET6: error = in6_gif_output(ifp, family, m); break; #endif default: m_freem(m); error = ENETDOWN; break; } if (error) ifp->if_oerrors++; else { ifp->if_opackets++; ifp->if_obytes += len; } } } void gif_input(m, af, ifp) struct mbuf *m; int af; struct ifnet *ifp; { int s, isr; struct ifqueue *ifq = NULL; if (ifp == NULL) { /* just in case */ m_freem(m); return; } m->m_pkthdr.rcvif = ifp; #if NBPFILTER > 0 if (ifp->if_bpf) { /* * We need to prepend the address family as * a four byte field. Cons up a dummy header * to pacify bpf. This is safe because bpf * will only read from the mbuf (i.e., it won't * try to free it or keep a pointer a to it). */ struct mbuf m0; u_int32_t af1 = af; m0.m_next = m; m0.m_len = 4; m0.m_data = (char *)&af1; #ifdef HAVE_OLD_BPF bpf_mtap(ifp, &m0); #else bpf_mtap(ifp->if_bpf, &m0); #endif } #endif /*NBPFILTER > 0*/ /* * Put the packet to the network layer input queue according to the * specified address family. * Note: older versions of gif_input directly called network layer * input functions, e.g. ip6_input, here. We changed the policy to * prevent too many recursive calls of such input functions, which * might cause kernel panic. But the change may introduce another * problem; if the input queue is full, packets are discarded. * The kernel stack overflow really happened, and we believed * queue-full rarely occurs, so we changed the policy. */ switch (af) { #ifdef INET case AF_INET: ifq = &ipintrq; isr = NETISR_IP; break; #endif #ifdef INET6 case AF_INET6: ifq = &ip6intrq; isr = NETISR_IPV6; break; #endif #ifdef ISO case AF_ISO: m = gif_eon_decap(ifp, m); if (!m) return; ifq = &clnlintrq; isr = NETISR_ISO; break; #endif default: m_freem(m); return; } s = splnet(); if (IF_QFULL(ifq)) { IF_DROP(ifq); /* update statistics */ m_freem(m); splx(s); return; } ifp->if_ipackets++; ifp->if_ibytes += m->m_pkthdr.len; IF_ENQUEUE(ifq, m); /* we need schednetisr since the address family may change */ schednetisr(isr); splx(s); } /* XXX how should we handle IPv6 scope on SIOC[GS]IFPHYADDR? */ int gif_ioctl(ifp, cmd, data) struct ifnet *ifp; u_long cmd; caddr_t data; { struct proc *p = curproc; /* XXX */ struct gif_softc *sc = (struct gif_softc*)ifp; struct ifreq *ifr = (struct ifreq*)data; int error = 0, size; struct sockaddr *dst, *src; #ifdef SIOCSIFMTU u_long mtu; #endif switch (cmd) { case SIOCSIFADDR: ifp->if_flags |= IFF_UP; break; case SIOCSIFDSTADDR: break; case SIOCADDMULTI: case SIOCDELMULTI: if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) break; switch (ifr->ifr_addr.sa_family) { #ifdef INET case AF_INET: /* IP supports Multicast */ break; #endif /* INET */ #ifdef INET6 case AF_INET6: /* IP6 supports Multicast */ break; #endif /* INET6 */ default: /* Other protocols doesn't support Multicast */ error = EAFNOSUPPORT; break; } break; #ifdef SIOCSIFMTU /* xxx */ case SIOCGIFMTU: break; case SIOCSIFMTU: if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) break; mtu = ifr->ifr_mtu; if (mtu < GIF_MTU_MIN || mtu > GIF_MTU_MAX) return (EINVAL); ifp->if_mtu = mtu; break; #endif /* SIOCSIFMTU */ #ifdef INET case SIOCSIFPHYADDR: #endif #ifdef INET6 case SIOCSIFPHYADDR_IN6: #endif /* INET6 */ case SIOCSLIFPHYADDR: if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) break; switch (cmd) { #ifdef INET case SIOCSIFPHYADDR: src = (struct sockaddr *) &(((struct in_aliasreq *)data)->ifra_addr); dst = (struct sockaddr *) &(((struct in_aliasreq *)data)->ifra_dstaddr); break; #endif #ifdef INET6 case SIOCSIFPHYADDR_IN6: src = (struct sockaddr *) &(((struct in6_aliasreq *)data)->ifra_addr); dst = (struct sockaddr *) &(((struct in6_aliasreq *)data)->ifra_dstaddr); break; #endif case SIOCSLIFPHYADDR: src = (struct sockaddr *) &(((struct if_laddrreq *)data)->addr); dst = (struct sockaddr *) &(((struct if_laddrreq *)data)->dstaddr); break; default: return EINVAL; } /* sa_family must be equal */ if (src->sa_family != dst->sa_family) return EINVAL; /* validate sa_len */ switch (src->sa_family) { #ifdef INET case AF_INET: if (src->sa_len != sizeof(struct sockaddr_in)) return EINVAL; break; #endif #ifdef INET6 case AF_INET6: if (src->sa_len != sizeof(struct sockaddr_in6)) return EINVAL; break; #endif default: return EAFNOSUPPORT; } switch (dst->sa_family) { #ifdef INET case AF_INET: if (dst->sa_len != sizeof(struct sockaddr_in)) return EINVAL; break; #endif #ifdef INET6 case AF_INET6: if (dst->sa_len != sizeof(struct sockaddr_in6)) return EINVAL; break; #endif default: return EAFNOSUPPORT; } /* check sa_family looks sane for the cmd */ switch (cmd) { case SIOCSIFPHYADDR: if (src->sa_family == AF_INET) break; return EAFNOSUPPORT; #ifdef INET6 case SIOCSIFPHYADDR_IN6: if (src->sa_family == AF_INET6) break; return EAFNOSUPPORT; #endif /* INET6 */ case SIOCSLIFPHYADDR: /* checks done in the above */ break; } error = gif_set_tunnel(&sc->gif_if, src, dst); break; #ifdef SIOCDIFPHYADDR case SIOCDIFPHYADDR: if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) break; gif_delete_tunnel(&sc->gif_if); break; #endif case SIOCGIFPSRCADDR: #ifdef INET6 case SIOCGIFPSRCADDR_IN6: #endif /* INET6 */ if (sc->gif_psrc == NULL) { error = EADDRNOTAVAIL; goto bad; } src = sc->gif_psrc; switch (cmd) { #ifdef INET case SIOCGIFPSRCADDR: dst = &ifr->ifr_addr; size = sizeof(ifr->ifr_addr); break; #endif /* INET */ #ifdef INET6 case SIOCGIFPSRCADDR_IN6: dst = (struct sockaddr *) &(((struct in6_ifreq *)data)->ifr_addr); size = sizeof(((struct in6_ifreq *)data)->ifr_addr); break; #endif /* INET6 */ default: error = EADDRNOTAVAIL; goto bad; } if (src->sa_len > size) return EINVAL; bcopy((caddr_t)src, (caddr_t)dst, src->sa_len); break; case SIOCGIFPDSTADDR: #ifdef INET6 case SIOCGIFPDSTADDR_IN6: #endif /* INET6 */ if (sc->gif_pdst == NULL) { error = EADDRNOTAVAIL; goto bad; } src = sc->gif_pdst; switch (cmd) { #ifdef INET case SIOCGIFPDSTADDR: dst = &ifr->ifr_addr; size = sizeof(ifr->ifr_addr); break; #endif /* INET */ #ifdef INET6 case SIOCGIFPDSTADDR_IN6: dst = (struct sockaddr *) &(((struct in6_ifreq *)data)->ifr_addr); size = sizeof(((struct in6_ifreq *)data)->ifr_addr); break; #endif /* INET6 */ default: error = EADDRNOTAVAIL; goto bad; } if (src->sa_len > size) return EINVAL; bcopy((caddr_t)src, (caddr_t)dst, src->sa_len); break; case SIOCGLIFPHYADDR: if (sc->gif_psrc == NULL || sc->gif_pdst == NULL) { error = EADDRNOTAVAIL; goto bad; } /* copy src */ src = sc->gif_psrc; dst = (struct sockaddr *) &(((struct if_laddrreq *)data)->addr); size = sizeof(((struct if_laddrreq *)data)->addr); if (src->sa_len > size) return EINVAL; bcopy((caddr_t)src, (caddr_t)dst, src->sa_len); /* copy dst */ src = sc->gif_pdst; dst = (struct sockaddr *) &(((struct if_laddrreq *)data)->dstaddr); size = sizeof(((struct if_laddrreq *)data)->dstaddr); if (src->sa_len > size) return EINVAL; bcopy((caddr_t)src, (caddr_t)dst, src->sa_len); break; case SIOCSIFFLAGS: /* if_ioctl() takes care of it */ break; default: error = EINVAL; break; } bad: return error; } int gif_set_tunnel(ifp, src, dst) struct ifnet *ifp; struct sockaddr *src; struct sockaddr *dst; { struct gif_softc *sc = (struct gif_softc *)ifp; struct gif_softc *sc2; struct sockaddr *osrc, *odst, *sa; int s; int error; s = splsoftnet(); for (sc2 = LIST_FIRST(&gif_softc_list); sc2 != NULL; sc2 = LIST_NEXT(sc2, gif_list)) { if (sc2 == sc) continue; if (!sc2->gif_pdst || !sc2->gif_psrc) continue; if (sc2->gif_pdst->sa_family != dst->sa_family || sc2->gif_pdst->sa_len != dst->sa_len || sc2->gif_psrc->sa_family != src->sa_family || sc2->gif_psrc->sa_len != src->sa_len) continue; /* can't configure same pair of address onto two gifs */ if (bcmp(sc2->gif_pdst, dst, dst->sa_len) == 0 && bcmp(sc2->gif_psrc, src, src->sa_len) == 0) { error = EADDRNOTAVAIL; goto bad; } /* XXX both end must be valid? (I mean, not 0.0.0.0) */ } /* XXX we can detach from both, but be polite just in case */ if (sc->gif_psrc) switch (sc->gif_psrc->sa_family) { #ifdef INET case AF_INET: (void)in_gif_detach(sc); break; #endif #ifdef INET6 case AF_INET6: (void)in6_gif_detach(sc); break; #endif } #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS sc->gif_si = softintr_establish(IPL_SOFTNET, gifintr, sc); if (sc->gif_si == NULL) { error = ENOMEM; goto bad; } #endif osrc = sc->gif_psrc; sa = (struct sockaddr *)malloc(src->sa_len, M_IFADDR, M_WAITOK); bcopy((caddr_t)src, (caddr_t)sa, src->sa_len); sc->gif_psrc = sa; odst = sc->gif_pdst; sa = (struct sockaddr *)malloc(dst->sa_len, M_IFADDR, M_WAITOK); bcopy((caddr_t)dst, (caddr_t)sa, dst->sa_len); sc->gif_pdst = sa; switch (sc->gif_psrc->sa_family) { #ifdef INET case AF_INET: error = in_gif_attach(sc); break; #endif #ifdef INET6 case AF_INET6: error = in6_gif_attach(sc); break; #endif } if (error) { /* rollback */ free((caddr_t)sc->gif_psrc, M_IFADDR); free((caddr_t)sc->gif_pdst, M_IFADDR); sc->gif_psrc = osrc; sc->gif_pdst = odst; goto bad; } if (osrc) free((caddr_t)osrc, M_IFADDR); if (odst) free((caddr_t)odst, M_IFADDR); if (sc->gif_psrc && sc->gif_pdst) ifp->if_flags |= IFF_RUNNING; else ifp->if_flags &= ~IFF_RUNNING; splx(s); return 0; bad: #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS if (sc->gif_si) { softintr_disestablish(sc->gif_si); sc->gif_si = NULL; } #endif if (sc->gif_psrc && sc->gif_pdst) ifp->if_flags |= IFF_RUNNING; else ifp->if_flags &= ~IFF_RUNNING; splx(s); return error; } void gif_delete_tunnel(ifp) struct ifnet *ifp; { struct gif_softc *sc = (struct gif_softc *)ifp; int s; s = splsoftnet(); #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS if (sc->gif_si) { softintr_disestablish(sc->gif_si); sc->gif_si = NULL; } #endif if (sc->gif_psrc) { free((caddr_t)sc->gif_psrc, M_IFADDR); sc->gif_psrc = NULL; } if (sc->gif_pdst) { free((caddr_t)sc->gif_pdst, M_IFADDR); sc->gif_pdst = NULL; } /* it is safe to detach from both */ #ifdef INET (void)in_gif_detach(sc); #endif #ifdef INET6 (void)in6_gif_detach(sc); #endif if (sc->gif_psrc && sc->gif_pdst) ifp->if_flags |= IFF_RUNNING; else ifp->if_flags &= ~IFF_RUNNING; splx(s); } #ifdef ISO struct eonhdr { u_int8_t version; u_int8_t class; u_int16_t cksum; }; /* * prepend EON header to ISO PDU */ static struct mbuf * gif_eon_encap(struct mbuf *m) { struct eonhdr *ehdr; M_PREPEND(m, sizeof(*ehdr), M_DONTWAIT); if (m && m->m_len < sizeof(*ehdr)) m = m_pullup(m, sizeof(*ehdr)); if (m == NULL) return NULL; ehdr = mtod(m, struct eonhdr *); ehdr->version = 1; ehdr->class = 0; /* always unicast */ #if 0 /* calculate the checksum of the eonhdr */ { struct mbuf mhead; memset(&mhead, 0, sizeof(mhead)); ehdr->cksum = 0; mhead.m_data = (caddr_t)ehdr; mhead.m_len = sizeof(*ehdr); mhead.m_next = 0; iso_gen_csum(&mhead, offsetof(struct eonhdr, cksum), mhead.m_len); } #else /* since the data is always constant we'll just plug the value in */ ehdr->cksum = htons(0xfc02); #endif return m; } /* * remove EON header and check checksum */ static struct mbuf * gif_eon_decap(struct ifnet *ifp, struct mbuf *m) { struct eonhdr *ehdr; if (m->m_len < sizeof(*ehdr) && (m = m_pullup(m, sizeof(*ehdr))) == NULL) { ifp->if_ierrors++; return NULL; } if (iso_check_csum(m, sizeof(struct eonhdr))) { m_freem(m); return NULL; } m_adj(m, sizeof(*ehdr)); return m; } #endif /*ISO*/