freebsd-dev/sys/netipsec/xform_ipip.c
Bjoern A. Zeeb 19ad9831df Add sysctls to if_enc(4) to control whether the firewalls or
bpf will see inner and outer headers or just inner or outer
headers for incoming and outgoing IPsec packets.

This is useful in bpf to not have over long lines for debugging
or selcting packets based on the inner headers.
It also properly defines the behavior of what the firewalls see.

Last but not least it gives you if_enc(4) for IPv6 as well.

[ As some auxiliary state was not available in the later
  input path we save it in the tdbi. That way tcpdump can give a
  consistent view of either of (authentic,confidential) for both
  before and after states. ]

Discussed with:	thompsa (2007-04-25, basic idea of unifying paths)
Reviewed by:	thompsa, gnn
2007-11-28 22:33:53 +00:00

704 lines
16 KiB
C

/* $FreeBSD$ */
/* $OpenBSD: ip_ipip.c,v 1.25 2002/06/10 18:04:55 itojun 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 "opt_inet.h"
#include "opt_inet6.h"
#include "opt_enc.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/kernel.h>
#include <sys/protosw.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/pfil.h>
#include <net/route.h>
#include <net/netisr.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_ecn.h>
#include <netinet/ip_var.h>
#include <netinet/ip_encap.h>
#include <netipsec/ipsec.h>
#include <netipsec/xform.h>
#include <netipsec/ipip_var.h>
#ifdef MROUTING
#include <netinet/ip_mroute.h>
#endif
#ifdef INET6
#include <netinet/ip6.h>
#include <netipsec/ipsec6.h>
#include <netinet6/ip6_ecn.h>
#include <netinet6/in6_var.h>
#include <netinet6/ip6protosw.h>
#endif
#include <netipsec/key.h>
#include <netipsec/key_debug.h>
#include <machine/stdarg.h>
/*
* 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;
SYSCTL_DECL(_net_inet_ipip);
SYSCTL_INT(_net_inet_ipip, OID_AUTO,
ipip_allow, CTLFLAG_RW, &ipip_allow, 0, "");
SYSCTL_STRUCT(_net_inet_ipip, IPSECCTL_STATS,
stats, CTLFLAG_RD, &ipipstat, ipipstat, "");
/* XXX IPCOMP */
#define M_IPSEC (M_AUTHIPHDR|M_AUTHIPDGM|M_DECRYPTED)
static void _ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp);
#ifdef INET6
/*
* Really only a wrapper for ipip_input(), for use with IPv6.
*/
int
ip4_input6(struct mbuf **m, int *offp, int proto)
{
#if 0
/* If we do not accept IP-in-IP explicitly, drop. */
if (!ipip_allow && ((*m)->m_flags & M_IPSEC) == 0) {
DPRINTF(("%s: dropped due to policy\n", __func__));
ipipstat.ipips_pdrops++;
m_freem(*m);
return IPPROTO_DONE;
}
#endif
_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, int off)
{
#if 0
/* If we do not accept IP-in-IP explicitly, drop. */
if (!ipip_allow && (m->m_flags & M_IPSEC) == 0) {
DPRINTF(("%s: dropped due to policy\n", __func__));
ipipstat.ipips_pdrops++;
m_freem(m);
return;
}
#endif
_ipip_input(m, off, 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.
*/
static void
_ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp)
{
register struct sockaddr_in *sin;
register struct ifnet *ifp;
register struct ifaddr *ifa;
struct ip *ipo;
#ifdef INET6
register 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;
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(("%s: m_pullup (1) failed\n", __func__));
ipipstat.ipips_hdrops++;
return;
}
}
ipo = mtod(m, struct ip *);
#ifdef MROUTING
if (ipo->ip_v == IPVERSION && ipo->ip_p == IPPROTO_IPV4) {
if (IN_MULTICAST(((struct ip *)((char *) ipo + iphlen))->ip_dst.s_addr)) {
ipip_mroute_input (m, iphlen);
return;
}
}
#endif /* MROUTING */
/* 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: unknown ip version %u (outer)", v>>4);
}
/* 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(("%s: m_pullup (2) failed\n", __func__));
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;
ip_ecn_egress(ip4_ipsec_ecn, &otos, &ipo->ip_tos);
break;
#endif /* INET */
#ifdef INET6
case 6:
ip6 = (struct ip6_hdr *) ipo;
nxt = ip6->ip6_nxt;
itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
ip_ecn_egress(ip6_ipsec_ecn, &otos, &itos);
ip6->ip6_flow &= ~htonl(0xff << 20);
ip6->ip6_flow |= htonl((u_int32_t) itos << 20);
break;
#endif
default:
panic("ipip_input: unknown ip version %u (inner)", v>>4);
}
/* Check for local address spoofing. */
if ((m->m_pkthdr.rcvif == NULL ||
!(m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK)) &&
ipip_allow != 2) {
IFNET_RLOCK();
TAILQ_FOREACH(ifp, &ifnet, if_link) {
TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
#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);
IFNET_RUNLOCK();
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);
IFNET_RUNLOCK();
return;
}
}
#endif /* INET6 */
}
}
IFNET_RUNLOCK();
}
/* Statistics */
ipipstat.ipips_ibytes += m->m_pkthdr.len - iphlen;
#ifdef DEV_ENC
switch (v >> 4) {
#ifdef INET
case 4:
ipsec_bpf(m, NULL, AF_INET, ENC_IN|ENC_AFTER);
break;
#endif
#ifdef INET6
case 6:
ipsec_bpf(m, NULL, AF_INET6, ENC_IN|ENC_AFTER);
break;
#endif
default:
panic("%s: bogus ip version %u", __func__, v>>4);
}
/* pass the mbuf to enc0 for packet filtering */
if (ipsec_filter(&m, PFIL_IN, ENC_IN|ENC_AFTER) != 0)
return;
#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 (v >> 4) {
#ifdef INET
case 4:
isr = NETISR_IP;
break;
#endif
#ifdef INET6
case 6:
isr = NETISR_IPV6;
break;
#endif
default:
panic("%s: bogus ip version %u", __func__, v>>4);
}
if (netisr_queue(isr, m)) { /* (0) on success. */
ipipstat.ipips_qfull++;
DPRINTF(("%s: packet dropped because of full queue\n",
__func__));
}
}
int
ipip_output(
struct mbuf *m,
struct ipsecrequest *isr,
struct mbuf **mp,
int skip,
int protoff
)
{
struct secasvar *sav;
u_int8_t tp, otos;
struct secasindex *saidx;
int error;
#ifdef INET
u_int8_t itos;
struct ip *ipo;
#endif /* INET */
#ifdef INET6
struct ip6_hdr *ip6, *ip6o;
#endif /* INET6 */
IPSEC_SPLASSERT_SOFTNET(__func__);
sav = isr->sav;
IPSEC_ASSERT(sav != NULL, ("null SA"));
IPSEC_ASSERT(sav->sah != NULL, ("null SAH"));
/* XXX Deal with empty TDB source/destination addresses. */
m_copydata(m, 0, 1, &tp);
tp = (tp >> 4) & 0xff; /* Get the IP version number. */
saidx = &sav->sah->saidx;
switch (saidx->dst.sa.sa_family) {
#ifdef INET
case AF_INET:
if (saidx->src.sa.sa_family != AF_INET ||
saidx->src.sin.sin_addr.s_addr == INADDR_ANY ||
saidx->dst.sin.sin_addr.s_addr == INADDR_ANY) {
DPRINTF(("%s: unspecified tunnel endpoint "
"address in SA %s/%08lx\n", __func__,
ipsec_address(&saidx->dst),
(u_long) ntohl(sav->spi)));
ipipstat.ipips_unspec++;
error = EINVAL;
goto bad;
}
M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
if (m == 0) {
DPRINTF(("%s: M_PREPEND failed\n", __func__));
ipipstat.ipips_hdrops++;
error = ENOBUFS;
goto bad;
}
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 = saidx->src.sin.sin_addr;
ipo->ip_dst = saidx->dst.sin.sin_addr;
ipo->ip_id = ip_newid();
/* 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 {
goto nofamily;
}
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(&saidx->dst.sin6.sin6_addr) ||
saidx->src.sa.sa_family != AF_INET6 ||
IN6_IS_ADDR_UNSPECIFIED(&saidx->src.sin6.sin6_addr)) {
DPRINTF(("%s: unspecified tunnel endpoint "
"address in SA %s/%08lx\n", __func__,
ipsec_address(&saidx->dst),
(u_long) ntohl(sav->spi)));
ipipstat.ipips_unspec++;
error = ENOBUFS;
goto bad;
}
/* scoped address handling */
ip6 = mtod(m, struct ip6_hdr *);
if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
ip6->ip6_src.s6_addr16[1] = 0;
if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
ip6->ip6_dst.s6_addr16[1] = 0;
M_PREPEND(m, sizeof(struct ip6_hdr), M_DONTWAIT);
if (m == 0) {
DPRINTF(("%s: M_PREPEND failed\n", __func__));
ipipstat.ipips_hdrops++;
error = ENOBUFS;
goto bad;
}
/* 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);
ip6o->ip6_hlim = ip_defttl;
ip6o->ip6_dst = saidx->dst.sin6.sin6_addr;
ip6o->ip6_src = saidx->src.sin6.sin6_addr;
#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 {
goto nofamily;
}
otos = 0;
ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
ip6o->ip6_flow |= htonl((u_int32_t) otos << 20);
break;
#endif /* INET6 */
default:
nofamily:
DPRINTF(("%s: unsupported protocol family %u\n", __func__,
saidx->dst.sa.sa_family));
ipipstat.ipips_family++;
error = EAFNOSUPPORT; /* XXX diffs from openbsd */
goto bad;
}
ipipstat.ipips_opackets++;
*mp = m;
#ifdef INET
if (saidx->dst.sa.sa_family == AF_INET) {
#if 0
if (sav->tdb_xform->xf_type == XF_IP4)
tdb->tdb_cur_bytes +=
m->m_pkthdr.len - sizeof(struct ip);
#endif
ipipstat.ipips_obytes += m->m_pkthdr.len - sizeof(struct ip);
}
#endif /* INET */
#ifdef INET6
if (saidx->dst.sa.sa_family == AF_INET6) {
#if 0
if (sav->tdb_xform->xf_type == XF_IP4)
tdb->tdb_cur_bytes +=
m->m_pkthdr.len - sizeof(struct ip6_hdr);
#endif
ipipstat.ipips_obytes +=
m->m_pkthdr.len - sizeof(struct ip6_hdr);
}
#endif /* INET6 */
return 0;
bad:
if (m)
m_freem(m);
*mp = NULL;
return (error);
}
#ifdef IPSEC
static int
ipe4_init(struct secasvar *sav, struct xformsw *xsp)
{
sav->tdb_xform = xsp;
return 0;
}
static int
ipe4_zeroize(struct secasvar *sav)
{
sav->tdb_xform = NULL;
return 0;
}
static int
ipe4_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
{
/* This is a rather serious mistake, so no conditional printing. */
printf("%s: should never be called\n", __func__);
if (m)
m_freem(m);
return EOPNOTSUPP;
}
static struct xformsw ipe4_xformsw = {
XF_IP4, 0, "IPv4 Simple Encapsulation",
ipe4_init, ipe4_zeroize, ipe4_input, ipip_output,
};
extern struct domain inetdomain;
static struct protosw ipe4_protosw =
{ SOCK_RAW, &inetdomain, IPPROTO_IPV4, PR_ATOMIC|PR_ADDR|PR_LASTHDR,
ip4_input,
0, 0, rip_ctloutput,
0,
0, 0, 0, 0,
&rip_usrreqs
};
#ifdef INET6
static struct ip6protosw ipe6_protosw =
{ SOCK_RAW, &inetdomain, IPPROTO_IPV6, PR_ATOMIC|PR_ADDR|PR_LASTHDR,
ip4_input6,
0, 0, rip_ctloutput,
0,
0, 0, 0, 0,
&rip_usrreqs
};
#endif
/*
* Check the encapsulated packet to see if we want it
*/
static int
ipe4_encapcheck(const struct mbuf *m, int off, int proto, void *arg)
{
/*
* Only take packets coming from IPSEC tunnels; the rest
* must be handled by the gif tunnel code. Note that we
* also return a minimum priority when we want the packet
* so any explicit gif tunnels take precedence.
*/
return ((m->m_flags & M_IPSEC) != 0 ? 1 : 0);
}
static void
ipe4_attach(void)
{
xform_register(&ipe4_xformsw);
/* attach to encapsulation framework */
/* XXX save return cookie for detach on module remove */
(void) encap_attach_func(AF_INET, -1,
ipe4_encapcheck, &ipe4_protosw, NULL);
#ifdef INET6
(void) encap_attach_func(AF_INET6, -1,
ipe4_encapcheck, (struct protosw *)&ipe6_protosw, NULL);
#endif
}
SYSINIT(ipe4_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, ipe4_attach, NULL);
#endif /* IPSEC */