NetBSD/sys/net/if_gre.c

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/* $NetBSD: if_gre.c,v 1.26 2002/02/24 17:22:20 martin 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 <hwr@pilhuhn.de>
*
* 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.
*/
/*
* Encapsulate L3 protocols into IP
* See RFC 1701 and 1702 for more details.
* If_gre is compatible with Cisco GRE tunnels, so you can
* have a NetBSD box as the other end of a tunnel interface of a Cisco
* router. See gre(4) for more details.
* Also supported: IP in IP encaps (proto 55) as of RFC 2004
*/
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#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_gre.c,v 1.26 2002/02/24 17:22:20 martin Exp $");
#include "opt_inet.h"
#include "opt_ns.h"
#include "bpfilter.h"
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/queue.h>
#if __NetBSD__
#include <sys/systm.h>
#endif
#include <machine/cpu.h>
#include <net/ethertypes.h>
#include <net/if.h>
#include <net/if_types.h>
#include <net/netisr.h>
#include <net/route.h>
#ifdef INET
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#else
#error "Huh? if_gre without inet?"
#endif
#ifdef NS
#include <netns/ns.h>
#include <netns/ns_if.h>
#endif
#ifdef NETATALK
#include <netatalk/at.h>
#include <netatalk/at_var.h>
#include <netatalk/at_extern.h>
#endif
#if NBPFILTER > 0
#include <sys/time.h>
#include <net/bpf.h>
#endif
#include <net/if_gre.h>
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/*
* XXX this is below the standard MTU of
* 1500 Bytes, allowing for headers,
* but we should possibly do path mtu discovery
* before changing if state to up to find the
* correct value
*/
#define GREMTU 1450
#define LINK_MASK (IFF_LINK0|IFF_LINK1|IFF_LINK2)
struct gre_softc_head gre_softc_list;
int ip_gre_ttl = GRE_TTL;
int gre_clone_create __P((struct if_clone *, int));
void gre_clone_destroy __P((struct ifnet *));
struct if_clone gre_cloner =
IF_CLONE_INITIALIZER("gre", gre_clone_create, gre_clone_destroy);
int gre_compute_route(struct gre_softc *sc);
void greattach __P((int));
/* ARGSUSED */
void
greattach(count)
int count;
{
LIST_INIT(&gre_softc_list);
if_clone_attach(&gre_cloner);
}
int
gre_clone_create(ifc, unit)
struct if_clone *ifc;
int unit;
{
struct gre_softc *sc;
sc = malloc(sizeof(struct gre_softc), M_DEVBUF, M_WAITOK);
memset(sc, 0, sizeof(struct gre_softc));
sprintf(sc->sc_if.if_xname, "%s%d", ifc->ifc_name, unit);
sc->sc_if.if_softc = sc;
sc->sc_if.if_type = IFT_OTHER;
sc->sc_if.if_addrlen = 4;
sc->sc_if.if_hdrlen = 24; /* IP + GRE */
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sc->sc_if.if_dlt = DLT_NULL;
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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->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY;
sc->g_proto = IPPROTO_GRE;
if_attach(&sc->sc_if);
if_alloc_sadl(&sc->sc_if);
#if NBPFILTER > 0
bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t));
#endif
LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list);
return (0);
}
void
gre_clone_destroy(ifp)
struct ifnet *ifp;
{
struct gre_softc *sc = ifp->if_softc;
LIST_REMOVE(sc, sc_list);
#if NBPFILTER > 0
bpfdetach(ifp);
#endif
if_detach(ifp);
free(sc, M_DEVBUF);
}
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/*
* 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 = ifp->if_softc;
struct greip *gh;
struct ip *inp;
u_char osrc;
u_short etype = 0;
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struct mobile_h mob_h;
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if ((ifp->if_flags & IFF_UP) == 0)
return ENETDOWN;
gh = NULL;
inp = NULL;
osrc = 0;
#if NBPFILTER >0
if (ifp->if_bpf) {
/* see comment of other if_foo.c files */
struct mbuf m0;
u_int32_t af = dst->sa_family;
m0.m_next = m;
m0.m_len = 4;
m0.m_data = (char *)&af;
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bpf_mtap(ifp->if_bpf, &m0);
}
#endif
m->m_flags &= ~(M_BCAST|M_MCAST);
if (sc->g_proto == IPPROTO_MOBILE) {
if (dst->sa_family == AF_INET) {
struct mbuf *m0;
int msiz;
inp = mtod(m, struct ip *);
memset(&mob_h, 0, 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.
* Else we also need to save and change the source
*/
if (in_hosteq(inp->ip_src, sc->g_src)) {
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_short *)&mob_h, msiz);
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);
return (ENOBUFS);
}
m0->m_next = m;
m->m_data += sizeof(struct ip);
m->m_len -= sizeof(struct ip);
m0->m_pkthdr.len = m->m_pkthdr.len + msiz;
m0->m_len = msiz + sizeof(struct ip);
m0->m_data += max_linkhdr;
memcpy(mtod(m0, caddr_t), (caddr_t)inp,
sizeof(struct ip));
m = m0;
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} else { /* we have some space left in the old one */
m->m_data -= msiz;
m->m_len += msiz;
m->m_pkthdr.len += msiz;
memmove(mtod(m, caddr_t), inp,
sizeof(struct ip));
}
inp=mtod(m, struct ip *);
memcpy((caddr_t)(inp + 1), &mob_h, (unsigned)msiz);
NTOHS(inp->ip_len);
inp->ip_len += msiz;
} else { /* AF_INET */
IF_DROP(&ifp->if_snd);
m_freem(m);
return (EINVAL);
}
} else if (sc->g_proto == IPPROTO_GRE) {
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switch (dst->sa_family) {
case AF_INET:
inp = mtod(m, struct ip *);
etype = ETHERTYPE_IP;
break;
#ifdef NETATALK
case AF_APPLETALK:
etype = ETHERTYPE_ATALK;
break;
#endif
#ifdef NS
case AF_NS:
etype = ETHERTYPE_NS;
break;
#endif
default:
IF_DROP(&ifp->if_snd);
m_freem(m);
return (EAFNOSUPPORT);
}
M_PREPEND(m, sizeof(struct greip), M_DONTWAIT);
} else {
error = EINVAL;
IF_DROP(&ifp->if_snd);
m_freem(m);
return (error);
}
if (m == NULL) {
IF_DROP(&ifp->if_snd);
return (ENOBUFS);
}
gh = mtod(m, struct greip *);
if (sc->g_proto == IPPROTO_GRE) {
/* we don't have any GRE flags for now */
memset((void *)&gh->gi_g, 0, 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;
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((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2;
((struct ip*)gh)->ip_ttl = ip_gre_ttl;
((struct ip*)gh)->ip_tos = inp->ip_tos;
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gh->gi_len = m->m_pkthdr.len;
}
ifp->if_opackets++;
ifp->if_obytes += m->m_pkthdr.len;
/* send it off */
error = ip_output(m, NULL, &sc->route, 0, NULL);
if (error)
ifp->if_oerrors++;
return (error);
}
int
gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
{
struct proc *p = curproc; /* XXX */
struct ifaddr *ifa = (struct ifaddr *)data;
struct ifreq *ifr = (struct ifreq *)data;
struct in_ifaddr *ia = (struct in_ifaddr *)data;
struct gre_softc *sc = ifp->if_softc;
int s;
struct sockaddr_in si;
struct sockaddr *sa = NULL;
int error;
error = 0;
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s = splnet();
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switch (cmd) {
case SIOCSIFADDR:
case SIOCSIFDSTADDR:
if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
break;
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/*
* set tunnel endpoints in case that we "only"
* have ip over ip encapsulation. This allows to
* set tunnel endpoints with ifconfig.
*/
if (ifa->ifa_addr->sa_family == AF_INET) {
sa = ifa->ifa_addr;
sc->g_src = (satosin(sa))->sin_addr;
sc->g_dst = ia->ia_dstaddr.sin_addr;
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);
if (gre_compute_route(sc) == 0)
ifp->if_flags |= IFF_UP;
}
}
break;
case SIOCSIFFLAGS:
if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
break;
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if ((sc->g_dst.s_addr == INADDR_ANY) ||
(sc->g_src.s_addr == INADDR_ANY))
ifp->if_flags &= ~IFF_UP;
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switch (ifr->ifr_flags & LINK_MASK) {
case IFF_LINK0:
sc->g_proto = IPPROTO_GRE;
ifp->if_flags |= IFF_LINK0;
ifp->if_flags &= ~(IFF_LINK1|IFF_LINK2);
break;
case IFF_LINK2:
sc->g_proto = IPPROTO_MOBILE;
ifp->if_flags |= IFF_LINK2;
ifp->if_flags &= ~(IFF_LINK0|IFF_LINK1);
break;
}
break;
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case SIOCSIFMTU:
if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
break;
if (ifr->ifr_mtu > GREMTU || 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 ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
break;
if (ifr == 0) {
error = EAFNOSUPPORT;
break;
}
switch (ifr->ifr_addr.sa_family) {
#ifdef INET
case AF_INET:
break;
#endif
default:
error = EAFNOSUPPORT;
break;
}
break;
case GRESPROTO:
if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
break;
sc->g_proto = ifr->ifr_flags;
switch (sc->g_proto) {
case IPPROTO_GRE :
ifp->if_flags |= IFF_LINK0;
ifp->if_flags &= ~(IFF_LINK1|IFF_LINK2);
break;
case IPPROTO_MOBILE :
ifp->if_flags |= IFF_LINK2;
ifp->if_flags &= ~(IFF_LINK1|IFF_LINK2);
break;
default:
ifp->if_flags &= ~(IFF_LINK0|IFF_LINK1|IFF_LINK2);
}
break;
case GREGPROTO:
ifr->ifr_flags = sc->g_proto;
break;
case GRESADDRS:
case GRESADDRD:
if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
break;
/*
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* 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;
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);
if (gre_compute_route(sc) == 0)
ifp->if_flags |= IFF_UP;
}
break;
case GREGADDRS:
si.sin_addr.s_addr = sc->g_src.s_addr;
sa = sintosa(&si);
ifr->ifr_addr = *sa;
break;
case GREGADDRD:
si.sin_addr.s_addr = sc->g_dst.s_addr;
sa = sintosa(&si);
ifr->ifr_addr = *sa;
break;
default:
error = EINVAL;
}
splx(s);
return (error);
}
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/*
* 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
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* gets src=a, dst=b tacked on and would from ip_ouput() 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.
*/
int
gre_compute_route(struct gre_softc *sc)
{
struct route *ro;
u_int32_t a, b, c;
ro = &sc->route;
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memset(ro, 0, 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
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* 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 ...
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*/
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
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= htonl(a);
}
#ifdef DIAGNOSTIC
printf("%s: searching a route to %s", sc->sc_if.if_xname,
inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr));
#endif
rtalloc(ro);
/*
* check if this returned a route at all and this route is no
* recursion to ourself
*/
if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) {
#ifdef DIAGNOSTIC
if (ro->ro_rt == NULL)
printf(" - no route found!\n");
else
printf(" - route loops back to ourself!\n");
#endif
return EADDRNOTAVAIL;
}
/*
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* 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;
#ifdef DIAGNOSTIC
printf(", choosing %s with gateway %s", ro->ro_rt->rt_ifp->if_xname,
inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr));
printf("\n");
#endif
return 0;
}
/*
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* do a checksum of a buffer - much like in_cksum, which operates on
* mbufs.
*/
u_short
gre_in_cksum(u_short *p, u_int len)
{
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u_int sum = 0;
int nwords = len >> 1;
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while (nwords-- != 0)
sum += *p++;
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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);
}