/* $OpenBSD: if_gre.c,v 1.46 2009/11/21 14:08:14 claudio Exp $ */ /* $NetBSD: if_gre.c,v 1.9 1999/10/25 19:18:11 drochner Exp $ */ /* * Copyright (c) 1998 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Heiko W.Rupp * * IPv6-over-GRE contributed by Gert Doering * * 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. */ /* * Encapsulate L3 protocols into IP, per RFC 1701 and 1702. * See gre(4) for more details. * Also supported: IP in IP encapsulation (proto 55) per RFC 2004. */ #include "gre.h" #if NGRE > 0 #include "bpfilter.h" #include "pf.h" #include #include #include #include #include #include #include #include #include #include #include #ifdef INET #include #include #include #include #include #include #else #error "if_gre used without inet" #endif #ifdef NETATALK #include #include #include #endif #if NBPFILTER > 0 #include #endif #if NPF > 0 #include #endif #include #ifndef GRE_RECURSION_LIMIT #define GRE_RECURSION_LIMIT 3 /* How many levels of recursion allowed */ #endif /* GRE_RECURSION_LIMIT */ /* * It is not easy to calculate the right value for a GRE MTU. * We leave this task to the admin and use the same default that * other vendors use. */ #define GREMTU 1476 int gre_clone_create(struct if_clone *, int); int gre_clone_destroy(struct ifnet *); struct gre_softc_head gre_softc_list; struct if_clone gre_cloner = IF_CLONE_INITIALIZER("gre", gre_clone_create, gre_clone_destroy); /* * We can control the acceptance of GRE and MobileIP packets by * altering the sysctl net.inet.gre.allow and net.inet.mobileip.allow values * respectively. Zero means drop them, all else is acceptance. We can also * control acceptance of WCCPv1-style GRE packets through the * net.inet.gre.wccp value, but be aware it depends upon normal GRE being * allowed as well. * */ int gre_allow = 0; int gre_wccp = 0; int ip_mobile_allow = 0; static void gre_compute_route(struct gre_softc *sc); void greattach(int n) { LIST_INIT(&gre_softc_list); if_clone_attach(&gre_cloner); } int gre_clone_create(struct if_clone *ifc, int unit) { struct gre_softc *sc; int s; sc = malloc(sizeof(*sc), M_DEVBUF, M_NOWAIT|M_ZERO); if (!sc) return (ENOMEM); snprintf(sc->sc_if.if_xname, sizeof sc->sc_if.if_xname, "%s%d", ifc->ifc_name, unit); sc->sc_if.if_softc = sc; sc->sc_if.if_type = IFT_TUNNEL; sc->sc_if.if_addrlen = 0; sc->sc_if.if_hdrlen = 24; /* IP + GRE */ sc->sc_if.if_mtu = GREMTU; sc->sc_if.if_flags = IFF_POINTOPOINT|IFF_MULTICAST; sc->sc_if.if_output = gre_output; sc->sc_if.if_ioctl = gre_ioctl; sc->sc_if.if_collisions = 0; sc->sc_if.if_ierrors = 0; sc->sc_if.if_oerrors = 0; sc->sc_if.if_ipackets = 0; sc->sc_if.if_opackets = 0; sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY; sc->g_proto = IPPROTO_GRE; sc->sc_if.if_flags |= IFF_LINK0; if_attach(&sc->sc_if); if_alloc_sadl(&sc->sc_if); #if NBPFILTER > 0 bpfattach(&sc->sc_if.if_bpf, &sc->sc_if, DLT_NULL, sizeof(u_int32_t)); #endif s = splnet(); LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list); splx(s); return (0); } int gre_clone_destroy(struct ifnet *ifp) { struct gre_softc *sc = ifp->if_softc; int s; s = splnet(); LIST_REMOVE(sc, sc_list); splx(s); if_detach(ifp); free(sc, M_DEVBUF); return (0); } /* * The output routine. Takes a packet and encapsulates it in the protocol * given by sc->g_proto. See also RFC 1701 and RFC 2004. */ int gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, struct rtentry *rt) { int error = 0; struct gre_softc *sc = (struct gre_softc *) (ifp->if_softc); struct greip *gh = NULL; struct ip *inp = NULL; u_int8_t ip_tos = 0; u_int16_t etype = 0; struct mobile_h mob_h; struct m_tag *mtag; if ((ifp->if_flags & IFF_UP) == 0 || sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) { m_freem(m); error = ENETDOWN; goto end; } #ifdef DIAGNOSTIC if (ifp->if_rdomain != rtable_l2(m->m_pkthdr.rdomain)) { printf("%s: trying to send packet on wrong domain. " "if %d vs. mbuf %d, AF %d\n", ifp->if_xname, ifp->if_rdomain, rtable_l2(m->m_pkthdr.rdomain), dst->sa_family); } #endif /* Try to limit infinite recursion through misconfiguration. */ for (mtag = m_tag_find(m, PACKET_TAG_GRE, NULL); mtag; mtag = m_tag_find(m, PACKET_TAG_GRE, mtag)) { if (!bcmp((caddr_t)(mtag + 1), &ifp, sizeof(struct ifnet *))) { IF_DROP(&ifp->if_snd); m_freem(m); error = EIO; goto end; } } mtag = m_tag_get(PACKET_TAG_GRE, sizeof(struct ifnet *), M_NOWAIT); if (mtag == NULL) { IF_DROP(&ifp->if_snd); m_freem(m); error = ENOBUFS; goto end; } bcopy(&ifp, (caddr_t)(mtag + 1), sizeof(struct ifnet *)); m_tag_prepend(m, mtag); m->m_flags &= ~(M_BCAST|M_MCAST); #if NBPFILTER >0 if (ifp->if_bpf) bpf_mtap_af(ifp->if_bpf, dst->sa_family, m, BPF_DIRECTION_OUT); #endif if (sc->g_proto == IPPROTO_MOBILE) { if (ip_mobile_allow == 0) { IF_DROP(&ifp->if_snd); m_freem(m); error = EACCES; goto end; } if (dst->sa_family == AF_INET) { struct mbuf *m0; int msiz; /* * Make sure the complete IP header (with options) * is in the first mbuf. */ if (m->m_len < sizeof(struct ip)) { m = m_pullup(m, sizeof(struct ip)); if (m == NULL) { IF_DROP(&ifp->if_snd); error = ENOBUFS; goto end; } else inp = mtod(m, struct ip *); if (m->m_len < inp->ip_hl << 2) { m = m_pullup(m, inp->ip_hl << 2); if (m == NULL) { IF_DROP(&ifp->if_snd); error = ENOBUFS; goto end; } } } inp = mtod(m, struct ip *); bzero(&mob_h, MOB_H_SIZ_L); mob_h.proto = (inp->ip_p) << 8; mob_h.odst = inp->ip_dst.s_addr; inp->ip_dst.s_addr = sc->g_dst.s_addr; /* * If the packet comes from our host, we only change * the destination address in the IP header. * Otherwise we need to save and change the source. */ if (inp->ip_src.s_addr == sc->g_src.s_addr) { msiz = MOB_H_SIZ_S; } else { mob_h.proto |= MOB_H_SBIT; mob_h.osrc = inp->ip_src.s_addr; inp->ip_src.s_addr = sc->g_src.s_addr; msiz = MOB_H_SIZ_L; } HTONS(mob_h.proto); mob_h.hcrc = gre_in_cksum((u_int16_t *) &mob_h, msiz); /* Squeeze in the mobility header */ if ((m->m_data - msiz) < m->m_pktdat) { /* Need new mbuf */ MGETHDR(m0, M_DONTWAIT, MT_HEADER); if (m0 == NULL) { IF_DROP(&ifp->if_snd); m_freem(m); error = ENOBUFS; goto end; } M_MOVE_HDR(m0, m); m0->m_len = msiz + (inp->ip_hl << 2); m0->m_data += max_linkhdr; m0->m_pkthdr.len = m->m_pkthdr.len + msiz; m->m_data += inp->ip_hl << 2; m->m_len -= inp->ip_hl << 2; bcopy((caddr_t) inp, mtod(m0, caddr_t), sizeof(struct ip)); m0->m_next = m; m = m0; } else { /* we have some space left in the old one */ m->m_data -= msiz; m->m_len += msiz; m->m_pkthdr.len += msiz; bcopy(inp, mtod(m, caddr_t), inp->ip_hl << 2); } /* Copy Mobility header */ inp = mtod(m, struct ip *); bcopy(&mob_h, (caddr_t)(inp + 1), (unsigned) msiz); inp->ip_len = htons(ntohs(inp->ip_len) + msiz); } else { /* AF_INET */ IF_DROP(&ifp->if_snd); m_freem(m); error = EINVAL; goto end; } } else if (sc->g_proto == IPPROTO_GRE) { if (gre_allow == 0) { IF_DROP(&ifp->if_snd); m_freem(m); error = EACCES; goto end; } switch(dst->sa_family) { case AF_INET: if (m->m_len < sizeof(struct ip)) { m = m_pullup(m, sizeof(struct ip)); if (m == NULL) { IF_DROP(&ifp->if_snd); error = ENOBUFS; goto end; } } inp = mtod(m, struct ip *); ip_tos = inp->ip_tos; etype = ETHERTYPE_IP; break; #ifdef NETATALK case AF_APPLETALK: etype = ETHERTYPE_AT; break; #endif #ifdef INET6 case AF_INET6: etype = ETHERTYPE_IPV6; break; #endif default: IF_DROP(&ifp->if_snd); m_freem(m); error = EAFNOSUPPORT; goto end; } M_PREPEND(m, sizeof(struct greip), M_DONTWAIT); } else { IF_DROP(&ifp->if_snd); m_freem(m); error = EINVAL; goto end; } if (m == NULL) { IF_DROP(&ifp->if_snd); error = ENOBUFS; goto end; } gh = mtod(m, struct greip *); if (sc->g_proto == IPPROTO_GRE) { /* We don't support any GRE flags for now */ bzero((void *) &gh->gi_g, sizeof(struct gre_h)); gh->gi_ptype = htons(etype); } gh->gi_pr = sc->g_proto; if (sc->g_proto != IPPROTO_MOBILE) { gh->gi_src = sc->g_src; gh->gi_dst = sc->g_dst; ((struct ip *) gh)->ip_hl = (sizeof(struct ip)) >> 2; ((struct ip *) gh)->ip_ttl = ip_defttl; ((struct ip *) gh)->ip_tos = ip_tos; gh->gi_len = htons(m->m_pkthdr.len); } ifp->if_opackets++; ifp->if_obytes += m->m_pkthdr.len; m->m_pkthdr.rdomain = sc->g_rtableid; #if NPF > 0 pf_pkt_addr_changed(m); #endif /* Send it off */ error = ip_output(m, (void *)NULL, &sc->route, 0, (void *)NULL, (void *)NULL); end: if (error) ifp->if_oerrors++; return (error); } int gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) { struct ifreq *ifr = (struct ifreq *) data; struct if_laddrreq *lifr = (struct if_laddrreq *)data; struct gre_softc *sc = ifp->if_softc; int s; struct sockaddr_in si; struct sockaddr *sa = NULL; int error = 0; struct proc *prc = curproc; /* XXX */ s = splnet(); switch(cmd) { case SIOCSIFADDR: ifp->if_flags |= IFF_UP; break; case SIOCSIFDSTADDR: break; case SIOCSIFFLAGS: if ((ifr->ifr_flags & IFF_LINK0) != 0) sc->g_proto = IPPROTO_GRE; else sc->g_proto = IPPROTO_MOBILE; break; case SIOCSIFMTU: if (ifr->ifr_mtu < 576) { error = EINVAL; break; } ifp->if_mtu = ifr->ifr_mtu; break; case SIOCGIFMTU: ifr->ifr_mtu = sc->sc_if.if_mtu; break; case SIOCADDMULTI: case SIOCDELMULTI: if (ifr == 0) { error = EAFNOSUPPORT; break; } switch (ifr->ifr_addr.sa_family) { #ifdef INET case AF_INET: break; #endif #ifdef INET6 case AF_INET6: break; #endif default: error = EAFNOSUPPORT; break; } break; case GRESPROTO: /* Check for superuser */ if ((error = suser(prc, 0)) != 0) break; sc->g_proto = ifr->ifr_flags; switch (sc->g_proto) { case IPPROTO_GRE: ifp->if_flags |= IFF_LINK0; break; case IPPROTO_MOBILE: ifp->if_flags &= ~IFF_LINK0; break; default: error = EPROTONOSUPPORT; break; } break; case GREGPROTO: ifr->ifr_flags = sc->g_proto; break; case GRESADDRS: case GRESADDRD: /* Check for superuser */ if ((error = suser(prc, 0)) != 0) break; /* * set tunnel endpoints, compute a less specific route * to the remote end and mark if as up */ sa = &ifr->ifr_addr; if (cmd == GRESADDRS ) sc->g_src = (satosin(sa))->sin_addr; if (cmd == GRESADDRD ) sc->g_dst = (satosin(sa))->sin_addr; recompute: if ((sc->g_src.s_addr != INADDR_ANY) && (sc->g_dst.s_addr != INADDR_ANY)) { if (sc->route.ro_rt != 0) { /* free old route */ RTFREE(sc->route.ro_rt); sc->route.ro_rt = (struct rtentry *) 0; } gre_compute_route(sc); ifp->if_flags |= IFF_UP; } break; case GREGADDRS: bzero(&si, sizeof(si)); si.sin_family = AF_INET; si.sin_len = sizeof(struct sockaddr_in); si.sin_addr.s_addr = sc->g_src.s_addr; sa = sintosa(&si); ifr->ifr_addr = *sa; break; case GREGADDRD: bzero(&si, sizeof(si)); si.sin_family = AF_INET; si.sin_len = sizeof(struct sockaddr_in); si.sin_addr.s_addr = sc->g_dst.s_addr; sa = sintosa(&si); ifr->ifr_addr = *sa; break; case SIOCSLIFPHYADDR: if ((error = suser(prc, 0)) != 0) break; if (lifr->addr.ss_family != AF_INET || lifr->dstaddr.ss_family != AF_INET) { error = EAFNOSUPPORT; break; } if (lifr->addr.ss_len != sizeof(si) || lifr->dstaddr.ss_len != sizeof(si)) { error = EINVAL; break; } sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; sc->g_dst = (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; goto recompute; case SIOCDIFPHYADDR: if ((error = suser(prc, 0)) != 0) break; sc->g_src.s_addr = INADDR_ANY; sc->g_dst.s_addr = INADDR_ANY; break; case SIOCGLIFPHYADDR: if (sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) { error = EADDRNOTAVAIL; break; } bzero(&si, sizeof(si)); si.sin_family = AF_INET; si.sin_len = sizeof(struct sockaddr_in); si.sin_addr.s_addr = sc->g_src.s_addr; memcpy(&lifr->addr, &si, sizeof(si)); si.sin_addr.s_addr = sc->g_dst.s_addr; memcpy(&lifr->dstaddr, &si, sizeof(si)); break; case SIOCSLIFPHYRTABLEID: if ((error = suser(prc, 0)) != 0) break; if (ifr->ifr_rdomainid < 0 || ifr->ifr_rdomainid > RT_TABLEID_MAX || !rtable_exists(ifr->ifr_rdomainid)) { error = EINVAL; break; } sc->g_rtableid = ifr->ifr_rdomainid; goto recompute; case SIOCGLIFPHYRTABLEID: ifr->ifr_rdomainid = sc->g_rtableid; break; default: error = ENOTTY; } splx(s); return (error); } /* * computes a route to our destination that is not the one * which would be taken by ip_output(), as this one will loop back to * us. If the interface is p2p as a--->b, then a routing entry exists * If we now send a packet to b (e.g. ping b), this will come down here * gets src=a, dst=b tacked on and would from ip_output() sent back to * if_gre. * Goal here is to compute a route to b that is less specific than * a-->b. We know that this one exists as in normal operation we have * at least a default route which matches. */ static void gre_compute_route(struct gre_softc *sc) { struct route *ro; u_int32_t a, b, c; ro = &sc->route; bzero(ro, sizeof(struct route)); ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = sc->g_dst; ro->ro_dst.sa_family = AF_INET; ro->ro_dst.sa_len = sizeof(ro->ro_dst); /* * toggle last bit, so our interface is not found, but a less * specific route. I'd rather like to specify a shorter mask, * but this is not possible. Should work though. XXX * there is a simpler way ... */ if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { a = ntohl(sc->g_dst.s_addr); b = a & 0x01; c = a & 0xfffffffe; b = b ^ 0x01; a = b | c; ((struct sockaddr_in *) &ro->ro_dst)->sin_addr.s_addr = htonl(a); } ro->ro_rt = rtalloc1(&ro->ro_dst, 1, sc->g_rtableid); if (ro->ro_rt == NULL) return; /* * Check whether we just created a loop. An even more paranoid * check would be against all GRE interfaces, but that would * not allow people to link GRE tunnels. */ if (ro->ro_rt->rt_ifp == &sc->sc_if) { RTFREE(ro->ro_rt); ro->ro_rt = NULL; return; } /* * now change it back - else ip_output will just drop * the route and search one to this interface ... */ if ((sc->sc_if.if_flags & IFF_LINK1) == 0) ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = sc->g_dst; } /* * do a checksum of a buffer - much like in_cksum, which operates on * mbufs. */ u_int16_t gre_in_cksum(u_int16_t *p, u_int len) { u_int32_t sum = 0; int nwords = len >> 1; while (nwords-- != 0) sum += *p++; if (len & 1) { union { u_short w; u_char c[2]; } u; u.c[0] = *(u_char *) p; u.c[1] = 0; sum += u.w; } /* end-around-carry */ sum = (sum >> 16) + (sum & 0xffff); sum += (sum >> 16); return (~sum); } #endif