/* $OpenBSD: ip_ipip.c,v 1.39 2007/02/10 15:34:22 claudio Exp $ */
/*
* The authors of this code are John Ioannidis (ji@tla.org),
* Angelos D. Keromytis (kermit@csd.uch.gr) and
* Niels Provos (provos@physnet.uni-hamburg.de).
*
* The original version of this code was written by John Ioannidis
* for BSD/OS in Athens, Greece, in November 1995.
*
* Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
* by Angelos D. Keromytis.
*
* Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
* and Niels Provos.
*
* Additional features in 1999 by Angelos D. Keromytis.
*
* Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
* Angelos D. Keromytis and Niels Provos.
* Copyright (c) 2001, Angelos D. Keromytis.
*
* Permission to use, copy, and modify this software with or without fee
* is hereby granted, provided that this entire notice is included in
* all copies of any software which is or includes a copy or
* modification of this software.
* You may use this code under the GNU public license if you so wish. Please
* contribute changes back to the authors under this freer than GPL license
* so that we may further the use of strong encryption without limitations to
* all.
*
* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
* REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
* MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
* PURPOSE.
*/
/*
* IP-inside-IP processing
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/bpf.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_ecn.h>
#ifdef MROUTING
#include <netinet/ip_mroute.h>
#endif
#include <netinet/ip_ipsp.h>
#include <netinet/ip_ipip.h>
#include "bpfilter.h"
#ifdef ENCDEBUG
#define DPRINTF(x) if (encdebug) printf x
#else
#define DPRINTF(x)
#endif
/*
* We can control the acceptance of IP4 packets by altering the sysctl
* net.inet.ipip.allow value. Zero means drop them, all else is acceptance.
*/
int ipip_allow = 0;
struct ipipstat ipipstat;
#ifdef INET6
/*
* Really only a wrapper for ipip_input(), for use with IPv6.
*/
int
ip4_input6(struct mbuf **m, int *offp, int proto)
{
/* If we do not accept IP-in-IP explicitly, drop. */
if (!ipip_allow && ((*m)->m_flags & (M_AUTH|M_CONF)) == 0) {
DPRINTF(("ip4_input6(): dropped due to policy\n"));
ipipstat.ipips_pdrops++;
m_freem(*m);
return IPPROTO_DONE;
}
ipip_input(*m, *offp, NULL);
return IPPROTO_DONE;
}
#endif /* INET6 */
#ifdef INET
/*
* Really only a wrapper for ipip_input(), for use with IPv4.
*/
void
ip4_input(struct mbuf *m, ...)
{
va_list ap;
int iphlen;
/* If we do not accept IP-in-IP explicitly, drop. */
if (!ipip_allow && (m->m_flags & (M_AUTH|M_CONF)) == 0) {
DPRINTF(("ip4_input(): dropped due to policy\n"));
ipipstat.ipips_pdrops++;
m_freem(m);
return;
}
va_start(ap, m);
iphlen = va_arg(ap, int);
va_end(ap);
ipip_input(m, iphlen, NULL);
}
#endif /* INET */
/*
* ipip_input gets called when we receive an IP{46} encapsulated packet,
* either because we got it at a real interface, or because AH or ESP
* were being used in tunnel mode (in which case the rcvif element will
* contain the address of the encX interface associated with the tunnel.
*/
void
ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp)
{
struct sockaddr_in *sin;
struct ifnet *ifp;
struct ifaddr *ifa;
struct ifqueue *ifq = NULL;
struct ip *ipo;
#ifdef INET6
struct sockaddr_in6 *sin6;
struct ip6_hdr *ip6 = NULL;
u_int8_t itos;
#endif
u_int8_t nxt;
int isr;
u_int8_t otos;
u_int8_t v;
int hlen, s;
ipipstat.ipips_ipackets++;
m_copydata(m, 0, 1, &v);
switch (v >> 4) {
#ifdef INET
case 4:
hlen = sizeof(struct ip);
break;
#endif /* INET */
#ifdef INET6
case 6:
hlen = sizeof(struct ip6_hdr);
break;
#endif
default:
ipipstat.ipips_family++;
m_freem(m);
return /* EAFNOSUPPORT */;
}
/* Bring the IP header in the first mbuf, if not there already */
if (m->m_len < hlen) {
if ((m = m_pullup(m, hlen)) == NULL) {
DPRINTF(("ipip_input(): m_pullup() failed\n"));
ipipstat.ipips_hdrops++;
return;
}
}
ipo = mtod(m, struct ip *);
/* Keep outer ecn field. */
switch (v >> 4) {
#ifdef INET
case 4:
otos = ipo->ip_tos;
break;
#endif /* INET */
#ifdef INET6
case 6:
otos = (ntohl(mtod(m, struct ip6_hdr *)->ip6_flow) >> 20) & 0xff;
break;
#endif
default:
panic("ipip_input: should never reach here");
}
/* Remove outer IP header */
m_adj(m, iphlen);
/* Sanity check */
if (m->m_pkthdr.len < sizeof(struct ip)) {
ipipstat.ipips_hdrops++;
m_freem(m);
return;
}
m_copydata(m, 0, 1, &v);
switch (v >> 4) {
#ifdef INET
case 4:
hlen = sizeof(struct ip);
break;
#endif /* INET */
#ifdef INET6
case 6:
hlen = sizeof(struct ip6_hdr);
break;
#endif
default:
ipipstat.ipips_family++;
m_freem(m);
return; /* EAFNOSUPPORT */
}
/*
* Bring the inner IP header in the first mbuf, if not there already.
*/
if (m->m_len < hlen) {
if ((m = m_pullup(m, hlen)) == NULL) {
DPRINTF(("ipip_input(): m_pullup() failed\n"));
ipipstat.ipips_hdrops++;
return;
}
}
/*
* RFC 1853 specifies that the inner TTL should not be touched on
* decapsulation. There's no reason this comment should be here, but
* this is as good as any a position.
*/
/* Some sanity checks in the inner IP header */
switch (v >> 4) {
#ifdef INET
case 4:
ipo = mtod(m, struct ip *);
nxt = ipo->ip_p;
if (!ip_ecn_egress(ECN_ALLOWED, &otos, &ipo->ip_tos)) {
m_freem(m);
return;
}
break;
#endif /* INET */
#ifdef INET6
case 6:
ip6 = (struct ip6_hdr *) ipo;
nxt = ip6->ip6_nxt;
itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
if (!ip_ecn_egress(ECN_ALLOWED, &otos, &itos)) {
m_freem(m);
return;
}
ip6->ip6_flow &= ~htonl(0xff << 20);
ip6->ip6_flow |= htonl((u_int32_t) itos << 20);
break;
#endif
default:
panic("ipip_input: should never reach here");
}
/* Check for local address spoofing. */
if ((m->m_pkthdr.rcvif == NULL ||
!(m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK)) &&
ipip_allow != 2) {
TAILQ_FOREACH(ifp, &ifnet, if_list) {
TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list) {
#ifdef INET
if (ipo) {
if (ifa->ifa_addr->sa_family !=
AF_INET)
continue;
sin = (struct sockaddr_in *) ifa->ifa_addr;
if (sin->sin_addr.s_addr ==
ipo->ip_src.s_addr) {
ipipstat.ipips_spoof++;
m_freem(m);
return;
}
}
#endif /* INET */
#ifdef INET6
if (ip6) {
if (ifa->ifa_addr->sa_family !=
AF_INET6)
continue;
sin6 = (struct sockaddr_in6 *) ifa->ifa_addr;
if (IN6_ARE_ADDR_EQUAL(&sin6->sin6_addr, &ip6->ip6_src)) {
ipipstat.ipips_spoof++;
m_freem(m);
return;
}
}
#endif /* INET6 */
}
}
}
/* Statistics */
ipipstat.ipips_ibytes += m->m_pkthdr.len - iphlen;
/*
* Interface pointer stays the same; if no IPsec processing has
* been done (or will be done), this will point to a normal
* interface. Otherwise, it'll point to an enc interface, which
* will allow a packet filter to distinguish between secure and
* untrusted packets.
*/
switch (v >> 4) {
#ifdef INET
case 4:
ifq = &ipintrq;
isr = NETISR_IP;
break;
#endif
#ifdef INET6
case 6:
ifq = &ip6intrq;
isr = NETISR_IPV6;
break;
#endif
default:
panic("ipip_input: should never reach here");
}
#if NBPFILTER > 0
if (gifp && gifp->if_bpf)
bpf_mtap_af(gifp->if_bpf, ifq == &ipintrq ? AF_INET : AF_INET6,
m, BPF_DIRECTION_IN);
#endif
s = splnet(); /* isn't it already? */
if (IF_QFULL(ifq)) {
IF_DROP(ifq);
m_freem(m);
ipipstat.ipips_qfull++;
splx(s);
DPRINTF(("ipip_input(): packet dropped because of full "
"queue\n"));
return;
}
IF_ENQUEUE(ifq, m);
schednetisr(isr);
splx(s);
return;
}
int
ipip_output(struct mbuf *m, struct tdb *tdb, struct mbuf **mp, int dummy,
int dummy2)
{
u_int8_t tp, otos;
#ifdef INET
u_int8_t itos;
struct ip *ipo;
#endif /* INET */
#ifdef INET6
struct ip6_hdr *ip6, *ip6o;
#endif /* INET6 */
/* XXX Deal with empty TDB source/destination addresses. */
m_copydata(m, 0, 1, &tp);
tp = (tp >> 4) & 0xff; /* Get the IP version number. */
switch (tdb->tdb_dst.sa.sa_family) {
#ifdef INET
case AF_INET:
if (tdb->tdb_src.sa.sa_family != AF_INET ||
tdb->tdb_src.sin.sin_addr.s_addr == INADDR_ANY ||
tdb->tdb_dst.sin.sin_addr.s_addr == INADDR_ANY) {
DPRINTF(("ipip_output(): unspecified tunnel endpoind "
"address in SA %s/%08x\n",
ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi)));
ipipstat.ipips_unspec++;
m_freem(m);
*mp = NULL;
return EINVAL;
}
M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
if (m == 0) {
DPRINTF(("ipip_output(): M_PREPEND failed\n"));
ipipstat.ipips_hdrops++;
*mp = NULL;
return ENOBUFS;
}
ipo = mtod(m, struct ip *);
ipo->ip_v = IPVERSION;
ipo->ip_hl = 5;
ipo->ip_len = htons(m->m_pkthdr.len);
ipo->ip_ttl = ip_defttl;
ipo->ip_sum = 0;
ipo->ip_src = tdb->tdb_src.sin.sin_addr;
ipo->ip_dst = tdb->tdb_dst.sin.sin_addr;
/*
* We do the htons() to prevent snoopers from determining our
* endianness.
*/
ipo->ip_id = htons(ip_randomid());
/* If the inner protocol is IP... */
if (tp == IPVERSION) {
/* Save ECN notification */
m_copydata(m, sizeof(struct ip) +
offsetof(struct ip, ip_tos),
sizeof(u_int8_t), (caddr_t) &itos);
ipo->ip_p = IPPROTO_IPIP;
/*
* We should be keeping tunnel soft-state and
* send back ICMPs if needed.
*/
m_copydata(m, sizeof(struct ip) +
offsetof(struct ip, ip_off),
sizeof(u_int16_t), (caddr_t) &ipo->ip_off);
NTOHS(ipo->ip_off);
ipo->ip_off &= ~(IP_DF | IP_MF | IP_OFFMASK);
HTONS(ipo->ip_off);
}
#ifdef INET6
else if (tp == (IPV6_VERSION >> 4)) {
u_int32_t itos32;
/* Save ECN notification. */
m_copydata(m, sizeof(struct ip) +
offsetof(struct ip6_hdr, ip6_flow),
sizeof(u_int32_t), (caddr_t) &itos32);
itos = ntohl(itos32) >> 20;
ipo->ip_p = IPPROTO_IPV6;
ipo->ip_off = 0;
}
#endif /* INET6 */
else {
m_freem(m);
*mp = NULL;
ipipstat.ipips_family++;
return EAFNOSUPPORT;
}
otos = 0;
ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
ipo->ip_tos = otos;
break;
#endif /* INET */
#ifdef INET6
case AF_INET6:
if (IN6_IS_ADDR_UNSPECIFIED(&tdb->tdb_dst.sin6.sin6_addr) ||
tdb->tdb_src.sa.sa_family != AF_INET6 ||
IN6_IS_ADDR_UNSPECIFIED(&tdb->tdb_src.sin6.sin6_addr)) {
DPRINTF(("ipip_output(): unspecified tunnel endpoind "
"address in SA %s/%08x\n",
ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi)));
ipipstat.ipips_unspec++;
m_freem(m);
*mp = NULL;
return ENOBUFS;
}
/* scoped address handling */
ip6 = mtod(m, struct ip6_hdr *);
if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src))
ip6->ip6_src.s6_addr16[1] = 0;
if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst))
ip6->ip6_dst.s6_addr16[1] = 0;
M_PREPEND(m, sizeof(struct ip6_hdr), M_DONTWAIT);
if (m == 0) {
DPRINTF(("ipip_output(): M_PREPEND failed\n"));
ipipstat.ipips_hdrops++;
*mp = NULL;
return ENOBUFS;
}
/* Initialize IPv6 header */
ip6o = mtod(m, struct ip6_hdr *);
ip6o->ip6_flow = 0;
ip6o->ip6_vfc &= ~IPV6_VERSION_MASK;
ip6o->ip6_vfc |= IPV6_VERSION;
ip6o->ip6_plen = htons(m->m_pkthdr.len - sizeof(*ip6o));
ip6o->ip6_hlim = ip_defttl;
in6_embedscope(&ip6o->ip6_src, &tdb->tdb_src.sin6, NULL, NULL);
in6_embedscope(&ip6o->ip6_dst, &tdb->tdb_dst.sin6, NULL, NULL);
#ifdef INET
if (tp == IPVERSION) {
/* Save ECN notification */
m_copydata(m, sizeof(struct ip6_hdr) +
offsetof(struct ip, ip_tos), sizeof(u_int8_t),
(caddr_t) &itos);
/* This is really IPVERSION. */
ip6o->ip6_nxt = IPPROTO_IPIP;
}
else
#endif /* INET */
if (tp == (IPV6_VERSION >> 4)) {
u_int32_t itos32;
/* Save ECN notification. */
m_copydata(m, sizeof(struct ip6_hdr) +
offsetof(struct ip6_hdr, ip6_flow),
sizeof(u_int32_t), (caddr_t) &itos32);
itos = ntohl(itos32) >> 20;
ip6o->ip6_nxt = IPPROTO_IPV6;
} else {
m_freem(m);
*mp = NULL;
ipipstat.ipips_family++;
return EAFNOSUPPORT;
}
otos = 0;
ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
ip6o->ip6_flow |= htonl((u_int32_t) otos << 20);
break;
#endif /* INET6 */
default:
DPRINTF(("ipip_output(): unsupported protocol family %d\n",
tdb->tdb_dst.sa.sa_family));
m_freem(m);
*mp = NULL;
ipipstat.ipips_family++;
return EAFNOSUPPORT;
}
ipipstat.ipips_opackets++;
*mp = m;
#ifdef INET
if (tdb->tdb_dst.sa.sa_family == AF_INET) {
if (tdb->tdb_xform->xf_type == XF_IP4)
tdb->tdb_cur_bytes +=
m->m_pkthdr.len - sizeof(struct ip);
ipipstat.ipips_obytes += m->m_pkthdr.len - sizeof(struct ip);
}
#endif /* INET */
#ifdef INET6
if (tdb->tdb_dst.sa.sa_family == AF_INET6) {
if (tdb->tdb_xform->xf_type == XF_IP4)
tdb->tdb_cur_bytes +=
m->m_pkthdr.len - sizeof(struct ip6_hdr);
ipipstat.ipips_obytes +=
m->m_pkthdr.len - sizeof(struct ip6_hdr);
}
#endif /* INET6 */
return 0;
}
#ifdef IPSEC
int
ipe4_attach()
{
return 0;
}
int
ipe4_init(struct tdb *tdbp, struct xformsw *xsp, struct ipsecinit *ii)
{
tdbp->tdb_xform = xsp;
return 0;
}
int
ipe4_zeroize(struct tdb *tdbp)
{
return 0;
}
void
ipe4_input(struct mbuf *m, ...)
{
/* This is a rather serious mistake, so no conditional printing. */
printf("ipe4_input(): should never be called\n");
if (m)
m_freem(m);
}
#endif /* IPSEC */
int
ipip_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
size_t newlen)
{
/* All sysctl names at this level are terminal. */
if (namelen != 1)
return (ENOTDIR);
switch (name[0]) {
case IPIPCTL_ALLOW:
return (sysctl_int(oldp, oldlenp, newp, newlen, &ipip_allow));
default:
return (ENOPROTOOPT);
}
/* NOTREACHED */
}