/* $FreeBSD$ */
/* $KAME: if_stf.c,v 1.42 2000/08/15 07:24:23 itojun Exp $ */
/*
* Copyright (C) 2000 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.
*/
/*
* 6to4 interface, based on draft-ietf-ngtrans-6to4-06.txt.
*
* 6to4 interface is NOT capable of link-layer (I mean, IPv4) multicasting.
* There is no address mapping defined from IPv6 multicast address to IPv4
* address. Therefore, we do not have IFF_MULTICAST on the interface.
*
* Due to the lack of address mapping for link-local addresses, we cannot
* throw packets toward link-local addresses (fe80::x). Also, we cannot throw
* packets to link-local multicast addresses (ff02::x).
*
* Here are interesting symptoms due to the lack of link-local address:
*
* Unicast routing exchange:
* - RIPng: Impossible. Uses link-local multicast packet toward ff02::9,
* and link-local addresses as nexthop.
* - OSPFv6: Impossible. OSPFv6 assumes that there's link-local address
* assigned to the link, and makes use of them. Also, HELLO packets use
* link-local multicast addresses (ff02::5 and ff02::6).
* - BGP4+: Maybe. You can only use global address as nexthop, and global
* address as TCP endpoint address.
*
* Multicast routing protocols:
* - PIM: Hello packet cannot be used to discover adjacent PIM routers.
* Adjacent PIM routers must be configured manually (is it really spec-wise
* correct thing to do?).
*
* ICMPv6:
* - Redirects cannot be used due to the lack of link-local address.
*
* Starting from 04 draft, the specification suggests how to construct
* link-local address for 6to4 interface.
* However, it seems to have no real use and does not help the above symptom
* much. Even if we assign link-locals to interface, we cannot really
* use link-local unicast/multicast on top of 6to4 cloud, and the above
* analysis does not change.
*
* 6to4 interface has security issues. Refer to
* http://playground.iijlab.net/i-d/draft-itojun-ipv6-transition-abuse-00.txt
* for details. The code tries to filter out some of malicious packets.
* Note that there is no way to be 100% secure.
*/
#include "opt_inet.h"
#include "opt_inet6.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/mbuf.h>
#include <sys/errno.h>
#include <sys/protosw.h>
#include <sys/kernel.h>
#include <machine/cpu.h>
#include <sys/malloc.h>
#include <net/if.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/if_types.h>
#include <net/if_stf.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/in_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_gif.h>
#include <netinet6/in6_var.h>
#include <netinet/ip_ecn.h>
#include <netinet/ip_encap.h>
#include <machine/stdarg.h>
#include <net/net_osdep.h>
#include "bpf.h"
#define NBPFILTER NBPF
#include "stf.h"
#include "gif.h" /*XXX*/
#if NBPFILTER > 0
#include <net/bpf.h>
#endif
#if NGIF > 0
#include <net/if_gif.h>
#endif
#if NSTF > 0
#if NSTF != 1
# error only single stf interface allowed
#endif
#define IN6_IS_ADDR_6TO4(x) (ntohs((x)->s6_addr16[0]) == 0x2002)
#define GET_V4(x) ((struct in_addr *)(&(x)->s6_addr16[1]))
struct stf_softc {
struct ifnet sc_if; /* common area */
union {
struct route __sc_ro4;
struct route_in6 __sc_ro6; /* just for safety */
} __sc_ro46;
#define sc_ro __sc_ro46.__sc_ro4
const struct encaptab *encap_cookie;
};
static struct stf_softc *stf;
static int nstf;
#if NGIF > 0
extern int ip_gif_ttl; /*XXX*/
#else
static int ip_gif_ttl = 40; /*XXX*/
#endif
extern struct protosw in_stf_protosw;
void stfattach __P((void *));
static int stf_encapcheck __P((const struct mbuf *, int, int, void *));
static struct in6_ifaddr *stf_getsrcifa6 __P((struct ifnet *));
static int stf_output __P((struct ifnet *, struct mbuf *, struct sockaddr *,
struct rtentry *));
static int stf_checkaddr4 __P((struct in_addr *, struct ifnet *));
static int stf_checkaddr6 __P((struct in6_addr *, struct ifnet *));
static void stf_rtrequest __P((int, struct rtentry *, struct sockaddr *));
static int stf_ioctl __P((struct ifnet *, u_long, caddr_t));
void
stfattach(dummy)
void *dummy;
{
struct stf_softc *sc;
int i;
const struct encaptab *p;
nstf = NSTF;
stf = malloc(nstf * sizeof(struct stf_softc), M_DEVBUF, M_WAITOK);
bzero(stf, nstf * sizeof(struct stf_softc));
sc = stf;
/* XXX just in case... */
for (i = 0; i < nstf; i++) {
sc = &stf[i];
bzero(sc, sizeof(*sc));
sc->sc_if.if_name = "stf";
sc->sc_if.if_unit = i;
p = encap_attach_func(AF_INET, IPPROTO_IPV6, stf_encapcheck,
&in_stf_protosw, sc);
if (p == NULL) {
printf("%s: attach failed\n", if_name(&sc->sc_if));
continue;
}
sc->encap_cookie = p;
sc->sc_if.if_mtu = IPV6_MMTU;
sc->sc_if.if_flags = 0;
sc->sc_if.if_ioctl = stf_ioctl;
sc->sc_if.if_output = stf_output;
sc->sc_if.if_type = IFT_STF;
sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN;
if_attach(&sc->sc_if);
#if NBPFILTER > 0
#ifdef HAVE_OLD_BPF
bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
#else
bpfattach(&sc->sc_if.if_bpf, &sc->sc_if, DLT_NULL, sizeof(u_int));
#endif
#endif
}
}
PSEUDO_SET(stfattach, if_stf);
static int
stf_encapcheck(m, off, proto, arg)
const struct mbuf *m;
int off;
int proto;
void *arg;
{
struct ip ip;
struct in6_ifaddr *ia6;
struct stf_softc *sc;
struct in_addr a, b;
sc = (struct stf_softc *)arg;
if (sc == NULL)
return 0;
if ((sc->sc_if.if_flags & IFF_UP) == 0)
return 0;
if (proto != IPPROTO_IPV6)
return 0;
/* LINTED const cast */
m_copydata((struct mbuf *)m, 0, sizeof(ip), (caddr_t)&ip);
if (ip.ip_v != 4)
return 0;
ia6 = stf_getsrcifa6(&sc->sc_if);
if (ia6 == NULL)
return 0;
/*
* check if IPv4 dst matches the IPv4 address derived from the
* local 6to4 address.
* success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
*/
if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
sizeof(ip.ip_dst)) != 0)
return 0;
/*
* check if IPv4 src matches the IPv4 address derived from the
* local 6to4 address masked by prefixmask.
* success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
* fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
*/
bzero(&a, sizeof(a));
a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
b = ip.ip_src;
b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
if (a.s_addr != b.s_addr)
return 0;
/* stf interface makes single side match only */
return 32;
}
static struct in6_ifaddr *
stf_getsrcifa6(ifp)
struct ifnet *ifp;
{
struct ifaddr *ia;
struct in_ifaddr *ia4;
struct sockaddr_in6 *sin6;
struct in_addr in;
for (ia = TAILQ_FIRST(&ifp->if_addrlist);
ia;
ia = TAILQ_NEXT(ia, ifa_list))
{
if (ia->ifa_addr == NULL)
continue;
if (ia->ifa_addr->sa_family != AF_INET6)
continue;
sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
continue;
bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
ia4;
ia4 = TAILQ_NEXT(ia4, ia_link))
{
if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
break;
}
if (ia4 == NULL)
continue;
return (struct in6_ifaddr *)ia;
}
return NULL;
}
static int
stf_output(ifp, m, dst, rt)
struct ifnet *ifp;
struct mbuf *m;
struct sockaddr *dst;
struct rtentry *rt;
{
struct stf_softc *sc;
struct sockaddr_in6 *dst6;
struct sockaddr_in *dst4;
u_int8_t tos;
struct ip *ip;
struct ip6_hdr *ip6;
struct in6_ifaddr *ia6;
sc = (struct stf_softc*)ifp;
dst6 = (struct sockaddr_in6 *)dst;
/* just in case */
if ((ifp->if_flags & IFF_UP) == 0) {
m_freem(m);
return ENETDOWN;
}
/*
* If we don't have an ip4 address that match my inner ip6 address,
* we shouldn't generate output. Without this check, we'll end up
* using wrong IPv4 source.
*/
ia6 = stf_getsrcifa6(ifp);
if (ia6 == NULL) {
m_freem(m);
return ENETDOWN;
}
if (m->m_len < sizeof(*ip6)) {
m = m_pullup(m, sizeof(*ip6));
if (!m)
return ENOBUFS;
}
ip6 = mtod(m, struct ip6_hdr *);
tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
if (m && m->m_len < sizeof(struct ip))
m = m_pullup(m, sizeof(struct ip));
if (m == NULL)
return ENOBUFS;
ip = mtod(m, struct ip *);
bzero(ip, sizeof(*ip));
bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
&ip->ip_src, sizeof(ip->ip_src));
bcopy(GET_V4(&dst6->sin6_addr), &ip->ip_dst, sizeof(ip->ip_dst));
ip->ip_p = IPPROTO_IPV6;
ip->ip_ttl = ip_gif_ttl; /*XXX*/
ip->ip_len = m->m_pkthdr.len; /*host order*/
if (ifp->if_flags & IFF_LINK1)
ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
if (dst4->sin_family != AF_INET ||
bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
/* cache route doesn't match */
dst4->sin_family = AF_INET;
dst4->sin_len = sizeof(struct sockaddr_in);
bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
if (sc->sc_ro.ro_rt) {
RTFREE(sc->sc_ro.ro_rt);
sc->sc_ro.ro_rt = NULL;
}
}
if (sc->sc_ro.ro_rt == NULL) {
rtalloc(&sc->sc_ro);
if (sc->sc_ro.ro_rt == NULL) {
m_freem(m);
return ENETUNREACH;
}
}
return ip_output(m, NULL, &sc->sc_ro, 0, NULL);
}
static int
stf_checkaddr4(in, ifp)
struct in_addr *in;
struct ifnet *ifp; /* incoming interface */
{
struct in_ifaddr *ia4;
/*
* reject packets with the following address:
* 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
*/
if (IN_MULTICAST(ntohl(in->s_addr)))
return -1;
switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
case 0: case 127: case 255:
return -1;
}
/*
* reject packets with broadcast
*/
for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
ia4;
ia4 = TAILQ_NEXT(ia4, ia_link))
{
if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
continue;
if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
return -1;
}
/*
* perform ingress filter
*/
if (ifp) {
struct sockaddr_in sin;
struct rtentry *rt;
bzero(&sin, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_len = sizeof(struct sockaddr_in);
sin.sin_addr = *in;
rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
if (!rt)
return -1;
if (rt->rt_ifp != ifp) {
rtfree(rt);
return -1;
}
rtfree(rt);
}
return 0;
}
static int
stf_checkaddr6(in6, ifp)
struct in6_addr *in6;
struct ifnet *ifp; /* incoming interface */
{
/*
* check 6to4 addresses
*/
if (IN6_IS_ADDR_6TO4(in6))
return stf_checkaddr4(GET_V4(in6), ifp);
/*
* reject anything that look suspicious. the test is implemented
* in ip6_input too, but we check here as well to
* (1) reject bad packets earlier, and
* (2) to be safe against future ip6_input change.
*/
if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
return -1;
return 0;
}
void
#if __STDC__
in_stf_input(struct mbuf *m, ...)
#else
in_stf_input(m, va_alist)
register struct mbuf *m;
#endif
{
int off, proto;
struct stf_softc *sc;
struct ip *ip;
struct ip6_hdr *ip6;
u_int8_t otos, itos;
int len, isr;
struct ifqueue *ifq = NULL;
struct ifnet *ifp;
va_list ap;
va_start(ap, m);
off = va_arg(ap, int);
proto = va_arg(ap, int);
va_end(ap);
if (proto != IPPROTO_IPV6) {
m_freem(m);
return;
}
ip = mtod(m, struct ip *);
sc = (struct stf_softc *)encap_getarg(m);
if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
m_freem(m);
return;
}
ifp = &sc->sc_if;
/*
* perform sanity check against outer src/dst.
* for source, perform ingress filter as well.
*/
if (stf_checkaddr4(&ip->ip_dst, NULL) < 0 ||
stf_checkaddr4(&ip->ip_src, m->m_pkthdr.rcvif) < 0) {
m_freem(m);
return;
}
otos = ip->ip_tos;
m_adj(m, off);
if (m->m_len < sizeof(*ip6)) {
m = m_pullup(m, sizeof(*ip6));
if (!m)
return;
}
ip6 = mtod(m, struct ip6_hdr *);
/*
* perform sanity check against inner src/dst.
* for source, perform ingress filter as well.
*/
if (stf_checkaddr6(&ip6->ip6_dst, NULL) < 0 ||
stf_checkaddr6(&ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
m_freem(m);
return;
}
itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
if ((ifp->if_flags & IFF_LINK1) != 0)
ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
ip6->ip6_flow &= ~htonl(0xff << 20);
ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
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_int af = AF_INET6;
m0.m_next = m;
m0.m_len = 4;
m0.m_data = (char *)⁡
#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.
* See net/if_gif.c for possible issues with packet processing
* reorder due to extra queueing.
*/
ifq = &ip6intrq;
isr = NETISR_IPV6;
len = m->m_pkthdr.len;
if (! IF_HANDOFF(ifq, m, NULL))
return;
schednetisr(isr);
ifp->if_ipackets++;
ifp->if_ibytes += len;
}
/* ARGSUSED */
static void
stf_rtrequest(cmd, rt, sa)
int cmd;
struct rtentry *rt;
#if defined(__bsdi__) && _BSDI_VERSION >= 199802
struct rt_addrinfo *sa;
#else
struct sockaddr *sa;
#endif
{
if (rt)
rt->rt_rmx.rmx_mtu = IPV6_MMTU;
}
static int
stf_ioctl(ifp, cmd, data)
struct ifnet *ifp;
u_long cmd;
caddr_t data;
{
struct ifaddr *ifa;
struct ifreq *ifr;
struct sockaddr_in6 *sin6;
int error;
error = 0;
switch (cmd) {
case SIOCSIFADDR:
ifa = (struct ifaddr *)data;
if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
error = EAFNOSUPPORT;
break;
}
sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
ifa->ifa_rtrequest = stf_rtrequest;
ifp->if_flags |= IFF_UP;
} else
error = EINVAL;
break;
case SIOCADDMULTI:
case SIOCDELMULTI:
ifr = (struct ifreq *)data;
if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
;
else
error = EAFNOSUPPORT;
break;
default:
error = EINVAL;
break;
}
return error;
}
#endif /* NSTF > 0 */
