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src/sys/netinet/ip_ipip.c

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/* $OpenBSD: ip_ipip.c,v 1.101 2024/02/11 01:27:45 bluhm 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 "bpfilter.h"
#include "gif.h"
#include "pf.h"
#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/if_types.h>
#include <net/if_var.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/bpf.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#include <netinet6/ip6_var.h>
#include <netinet/ip_ecn.h>
#include <netinet/ip_ipip.h>
#ifdef MROUTING
#include <netinet/ip_mroute.h>
#endif
#if NPF > 0
#include <net/pfvar.h>
#endif
#ifdef ENCDEBUG
#define DPRINTF(fmt, args...) \
do { \
if (encdebug) \
printf("%s: " fmt "\n", __func__, ## args); \
} while (0)
#else
#define DPRINTF(fmt, args...) \
do { } while (0)
#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 cpumem *ipipcounters;
void
ipip_init(void)
{
ipipcounters = counters_alloc(ipips_ncounters);
}
/*
* Really only a wrapper for ipip_input_if(), for use with pr_input.
*/
int
ipip_input(struct mbuf **mp, int *offp, int nxt, int af)
{
struct ifnet *ifp;
/* If we do not accept IP-in-IP explicitly, drop. */
if (!ipip_allow && ((*mp)->m_flags & (M_AUTH|M_CONF)) == 0) {
DPRINTF("dropped due to policy");
ipipstat_inc(ipips_pdrops);
m_freemp(mp);
return IPPROTO_DONE;
}
ifp = if_get((*mp)->m_pkthdr.ph_ifidx);
if (ifp == NULL) {
m_freemp(mp);
return IPPROTO_DONE;
}
nxt = ipip_input_if(mp, offp, nxt, af, ifp);
if_put(ifp);
return nxt;
}
/*
* 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 ph_ifidx element
* will contain the index of the encX interface associated with the
* tunnel.
*/
int
ipip_input_if(struct mbuf **mp, int *offp, int proto, int oaf,
struct ifnet *ifp)
{
struct mbuf *m = *mp;
struct sockaddr_in *sin;
struct ip *ip;
#ifdef INET6
struct sockaddr_in6 *sin6;
struct ip6_hdr *ip6;
#endif
int mode, hlen;
u_int8_t itos, otos;
sa_family_t iaf;
ipipstat_inc(ipips_ipackets);
switch (oaf) {
case AF_INET:
hlen = sizeof(struct ip);
break;
#ifdef INET6
case AF_INET6:
hlen = sizeof(struct ip6_hdr);
break;
#endif
default:
unhandled_af(oaf);
}
/* Bring the IP header in the first mbuf, if not there already */
if (m->m_len < hlen) {
if ((m = *mp = m_pullup(m, hlen)) == NULL) {
DPRINTF("m_pullup() failed");
ipipstat_inc(ipips_hdrops);
goto bad;
}
}
/* Keep outer ecn field. */
switch (oaf) {
case AF_INET:
ip = mtod(m, struct ip *);
otos = ip->ip_tos;
break;
#ifdef INET6
case AF_INET6:
ip6 = mtod(m, struct ip6_hdr *);
otos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
break;
#endif
}
/* Remove outer IP header */
KASSERT(*offp > 0);
m_adj(m, *offp);
*offp = 0;
ip = NULL;
#ifdef INET6
ip6 = NULL;
#endif
switch (proto) {
case IPPROTO_IPV4:
hlen = sizeof(struct ip);
break;
#ifdef INET6
case IPPROTO_IPV6:
hlen = sizeof(struct ip6_hdr);
break;
#endif
default:
ipipstat_inc(ipips_family);
goto bad;
}
/* Sanity check */
if (m->m_pkthdr.len < hlen) {
ipipstat_inc(ipips_hdrops);
goto bad;
}
/*
* Bring the inner header into the first mbuf, if not there already.
*/
if (m->m_len < hlen) {
if ((m = *mp = m_pullup(m, hlen)) == NULL) {
DPRINTF("m_pullup() failed");
ipipstat_inc(ipips_hdrops);
goto bad;
}
}
/*
* 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 (proto) {
case IPPROTO_IPV4:
iaf = AF_INET;
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
if (m->m_pkthdr.len < hlen) {
ipipstat_inc(ipips_hdrops);
goto bad;
}
itos = ip->ip_tos;
mode = m->m_flags & (M_AUTH|M_CONF) ?
ECN_ALLOWED_IPSEC : ECN_ALLOWED;
if (!ip_ecn_egress(mode, &otos, &itos)) {
DPRINTF("ip_ecn_egress() failed");
ipipstat_inc(ipips_pdrops);
goto bad;
}
/* re-calculate the checksum if ip_tos was changed */
if (itos != ip->ip_tos)
ip_tos_patch(ip, itos);
break;
#ifdef INET6
case IPPROTO_IPV6:
iaf = AF_INET6;
ip6 = mtod(m, struct ip6_hdr *);
itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
if (!ip_ecn_egress(ECN_ALLOWED, &otos, &itos)) {
DPRINTF("ip_ecn_egress() failed");
ipipstat_inc(ipips_pdrops);
goto bad;
}
ip6->ip6_flow &= ~htonl(0xff << 20);
ip6->ip6_flow |= htonl((u_int32_t) itos << 20);
break;
#endif
}
/* Check for local address spoofing. */
if (!(ifp->if_flags & IFF_LOOPBACK) && ipip_allow != 2) {
struct sockaddr_storage ss;
struct rtentry *rt;
memset(&ss, 0, sizeof(ss));
if (ip) {
sin = (struct sockaddr_in *)&ss;
sin->sin_family = AF_INET;
sin->sin_len = sizeof(*sin);
sin->sin_addr = ip->ip_src;
#ifdef INET6
} else if (ip6) {
sin6 = (struct sockaddr_in6 *)&ss;
sin6->sin6_family = AF_INET6;
sin6->sin6_len = sizeof(*sin6);
sin6->sin6_addr = ip6->ip6_src;
#endif /* INET6 */
}
rt = rtalloc(sstosa(&ss), 0, m->m_pkthdr.ph_rtableid);
if ((rt != NULL) && (rt->rt_flags & RTF_LOCAL)) {
ipipstat_inc(ipips_spoof);
rtfree(rt);
goto bad;
}
rtfree(rt);
}
/* Statistics */
ipipstat_add(ipips_ibytes, m->m_pkthdr.len - hlen);
#if NBPFILTER > 0 && NGIF > 0
if (ifp->if_type == IFT_GIF && ifp->if_bpf != NULL)
bpf_mtap_af(ifp->if_bpf, iaf, m, BPF_DIRECTION_IN);
#endif
#if NPF > 0
pf_pkt_addr_changed(m);
#endif
/*
* 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 (proto) {
case IPPROTO_IPV4:
return ip_input_if(mp, offp, proto, oaf, ifp);
#ifdef INET6
case IPPROTO_IPV6:
return ip6_input_if(mp, offp, proto, oaf, ifp);
#endif
}
bad:
m_freemp(mp);
return IPPROTO_DONE;
}
int
ipip_output(struct mbuf **mp, struct tdb *tdb)
{
struct mbuf *m = *mp;
u_int8_t tp, otos, itos;
u_int64_t obytes;
struct ip *ipo;
#ifdef INET6
struct ip6_hdr *ip6, *ip6o;
#endif /* INET6 */
#ifdef ENCDEBUG
char buf[INET6_ADDRSTRLEN];
#endif
int error;
/* 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) {
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("unspecified tunnel endpoint address "
"in SA %s/%08x",
ipsp_address(&tdb->tdb_dst, buf, sizeof(buf)),
ntohl(tdb->tdb_spi));
ipipstat_inc(ipips_unspec);
error = EINVAL;
goto drop;
}
M_PREPEND(*mp, sizeof(struct ip), M_DONTWAIT);
if (*mp == NULL) {
DPRINTF("M_PREPEND failed");
ipipstat_inc(ipips_hdrops);
error = ENOBUFS;
goto drop;
}
m = *mp;
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);
ipo->ip_off = ntohs(ipo->ip_off);
ipo->ip_off &= ~(IP_DF | IP_MF | IP_OFFMASK);
ipo->ip_off = 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 {
ipipstat_inc(ipips_family);
error = EAFNOSUPPORT;
goto drop;
}
otos = 0;
ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
ipo->ip_tos = otos;
obytes = m->m_pkthdr.len - sizeof(struct ip);
if (tdb->tdb_xform->xf_type == XF_IP4)
tdb->tdb_cur_bytes += obytes;
break;
#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("unspecified tunnel endpoint address "
"in SA %s/%08x",
ipsp_address(&tdb->tdb_dst, buf, sizeof(buf)),
ntohl(tdb->tdb_spi));
ipipstat_inc(ipips_unspec);
error = EINVAL;
goto drop;
}
/* If the inner protocol is IPv6, clear link local scope */
if (tp == (IPV6_VERSION >> 4)) {
/* 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(*mp, sizeof(struct ip6_hdr), M_DONTWAIT);
if (*mp == NULL) {
DPRINTF("M_PREPEND failed");
ipipstat_inc(ipips_hdrops);
error = ENOBUFS;
goto drop;
}
m = *mp;
/* 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);
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
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 {
ipipstat_inc(ipips_family);
error = EAFNOSUPPORT;
goto drop;
}
otos = 0;
ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
ip6o->ip6_flow |= htonl((u_int32_t) otos << 20);
obytes = m->m_pkthdr.len - sizeof(struct ip6_hdr);
if (tdb->tdb_xform->xf_type == XF_IP4)
tdb->tdb_cur_bytes += obytes;
break;
#endif /* INET6 */
default:
DPRINTF("unsupported protocol family %d",
tdb->tdb_dst.sa.sa_family);
ipipstat_inc(ipips_family);
error = EPFNOSUPPORT;
goto drop;
}
ipipstat_pkt(ipips_opackets, ipips_obytes, obytes);
return 0;
drop:
m_freemp(mp);
return error;
}
#ifdef IPSEC
int
ipe4_attach(void)
{
return 0;
}
int
ipe4_init(struct tdb *tdbp, const struct xformsw *xsp, struct ipsecinit *ii)
{
tdbp->tdb_xform = xsp;
return 0;
}
int
ipe4_zeroize(struct tdb *tdbp)
{
return 0;
}
int
ipe4_input(struct mbuf **mp, struct tdb *tdb, int hlen, int proto)
{
/* This is a rather serious mistake, so no conditional printing. */
printf("%s: should never be called\n", __func__);
m_freemp(mp);
return EINVAL;
}
#endif /* IPSEC */
int
ipip_sysctl_ipipstat(void *oldp, size_t *oldlenp, void *newp)
{
struct ipipstat ipipstat;
CTASSERT(sizeof(ipipstat) == (ipips_ncounters * sizeof(uint64_t)));
memset(&ipipstat, 0, sizeof ipipstat);
counters_read(ipipcounters, (uint64_t *)&ipipstat, ipips_ncounters,
NULL);
return (sysctl_rdstruct(oldp, oldlenp, newp,
&ipipstat, sizeof(ipipstat)));
}
int
ipip_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
size_t newlen)
{
int error;
/* All sysctl names at this level are terminal. */
if (namelen != 1)
return (ENOTDIR);
switch (name[0]) {
case IPIPCTL_ALLOW:
NET_LOCK();
error = sysctl_int_bounded(oldp, oldlenp, newp, newlen,
&ipip_allow, 0, 2);
NET_UNLOCK();
return (error);
case IPIPCTL_STATS:
return (ipip_sysctl_ipipstat(oldp, oldlenp, newp));
default:
return (ENOPROTOOPT);
}
/* NOTREACHED */
}
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