NetBSD/sys/netipsec/ipsec_input.c

609 lines
16 KiB
C

/* $NetBSD: ipsec_input.c,v 1.78 2022/08/23 09:25:10 knakahara Exp $ */
/* $FreeBSD: ipsec_input.c,v 1.2.4.2 2003/03/28 20:32:53 sam Exp $ */
/* $OpenBSD: ipsec_input.c,v 1.63 2003/02/20 18:35:43 deraadt 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).
*
* 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.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ipsec_input.c,v 1.78 2022/08/23 09:25:10 knakahara Exp $");
/*
* IPsec input processing.
*/
#if defined(_KERNEL_OPT)
#include "opt_inet.h"
#endif
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <net/if.h>
#include <net/route.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/in_proto.h>
#include <netinet/udp.h>
#include <netinet/tcp.h>
#include <netinet/ip6.h>
#ifdef INET6
#include <netinet6/in6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/ip6_private.h>
#include <netinet6/scope6_var.h>
#endif
#include <netinet/in_pcb.h>
#include <netipsec/ipsec.h>
#include <netipsec/ipsec_private.h>
#ifdef INET6
#include <netipsec/ipsec6.h>
#endif
#include <netipsec/ah_var.h>
#include <netipsec/esp.h>
#include <netipsec/esp_var.h>
#include <netipsec/ipcomp_var.h>
#include <netipsec/key.h>
#include <netipsec/keydb.h>
#include <netipsec/xform.h>
#include <netinet6/ip6protosw.h>
#define IPSEC_ISTAT(p, x, y, z) \
do { \
switch (p) { \
case IPPROTO_ESP: \
ESP_STATINC(x); \
break; \
case IPPROTO_AH: \
AH_STATINC(y); \
break; \
default: \
IPCOMP_STATINC(z); \
break; \
} \
} while (/*CONSTCOND*/0)
/*
* fixup TCP/UDP checksum
*
* XXX: if we have NAT-OA payload from IKE server,
* we must do the differential update of checksum.
*
* XXX: NAT-OAi/NAT-OAr derived from IKE initiator/responder.
* how to know the IKE side from kernel?
*/
static struct mbuf *
ipsec4_fixup_checksum(struct mbuf *m)
{
struct ip *ip;
struct tcphdr *th;
struct udphdr *uh;
int poff, off;
int plen;
if (m->m_len < sizeof(*ip)) {
m = m_pullup(m, sizeof(*ip));
if (m == NULL)
return NULL;
}
ip = mtod(m, struct ip *);
poff = ip->ip_hl << 2;
plen = ntohs(ip->ip_len) - poff;
switch (ip->ip_p) {
case IPPROTO_TCP:
M_REGION_GET(th, struct tcphdr *, m, poff, sizeof(*th));
if (th == NULL)
return NULL;
off = th->th_off << 2;
if (off < sizeof(*th) || off > plen) {
m_freem(m);
return NULL;
}
th->th_sum = 0;
th->th_sum = in4_cksum(m, IPPROTO_TCP, poff, plen);
break;
case IPPROTO_UDP:
M_REGION_GET(uh, struct udphdr *, m, poff, sizeof(*uh));
if (uh == NULL)
return NULL;
off = sizeof(*uh);
if (off > plen) {
m_freem(m);
return NULL;
}
uh->uh_sum = 0;
uh->uh_sum = in4_cksum(m, IPPROTO_UDP, poff, plen);
break;
default:
/* no checksum */
return m;
}
return m;
}
static void
nat_t_ports_get(struct mbuf *m, uint16_t *dport, uint16_t *sport)
{
struct m_tag *tag;
if ((tag = m_tag_find(m, PACKET_TAG_IPSEC_NAT_T_PORTS))) {
*sport = ((uint16_t *)(tag + 1))[0];
*dport = ((uint16_t *)(tag + 1))[1];
} else
*sport = *dport = 0;
}
static uint32_t
spi_get(struct mbuf *m, int sproto, int skip)
{
uint32_t spi;
uint16_t cpi;
switch (sproto) {
case IPPROTO_ESP:
m_copydata(m, skip, sizeof(spi), &spi);
return spi;
case IPPROTO_AH:
m_copydata(m, skip + sizeof(spi), sizeof(spi), &spi);
return spi;
case IPPROTO_IPCOMP:
m_copydata(m, skip + sizeof(cpi), sizeof(cpi), &cpi);
return htonl(ntohs(cpi));
default:
panic("%s called with bad protocol number: %d\n", __func__,
sproto);
}
}
/*
* ipsec_common_input gets called when an IPsec-protected packet
* is received by IPv4 or IPv6. Its job is to find the right SA
* and call the appropriate transform. The transform callback
* takes care of further processing (like ingress filtering).
*/
static int
ipsec_common_input(struct mbuf *m, int skip, int protoff, int af, int sproto)
{
char buf[IPSEC_ADDRSTRLEN], buf2[IPSEC_ADDRSTRLEN];
union sockaddr_union src_address, dst_address;
struct secasvar *sav;
u_int32_t spi;
u_int16_t sport;
u_int16_t dport;
int s, error;
IPSEC_ISTAT(sproto, ESP_STAT_INPUT, AH_STAT_INPUT,
IPCOMP_STAT_INPUT);
KASSERT(m != NULL);
if ((sproto == IPPROTO_ESP && !esp_enable) ||
(sproto == IPPROTO_AH && !ah_enable) ||
(sproto == IPPROTO_IPCOMP && !ipcomp_enable)) {
m_freem(m);
IPSEC_ISTAT(sproto, ESP_STAT_PDROPS, AH_STAT_PDROPS,
IPCOMP_STAT_PDROPS);
return EOPNOTSUPP;
}
if (m->m_pkthdr.len - skip < 2 * sizeof(u_int32_t)) {
m_freem(m);
IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS,
IPCOMP_STAT_HDROPS);
IPSECLOG(LOG_DEBUG, "packet too small\n");
return EINVAL;
}
/* Retrieve the SPI from the relevant IPsec header */
spi = spi_get(m, sproto, skip);
/* find the source port for NAT-T */
nat_t_ports_get(m, &dport, &sport);
/*
* Find the SA and (indirectly) call the appropriate
* kernel crypto routine. The resulting mbuf chain is a valid
* IP packet ready to go through input processing.
*/
memset(&src_address, 0, sizeof (src_address));
memset(&dst_address, 0, sizeof(dst_address));
src_address.sa.sa_family = af;
dst_address.sa.sa_family = af;
switch (af) {
#ifdef INET
case AF_INET:
src_address.sin.sin_len = sizeof(struct sockaddr_in);
dst_address.sin.sin_len = sizeof(struct sockaddr_in);
m_copydata(m, offsetof(struct ip, ip_src),
sizeof(struct in_addr),
&src_address.sin.sin_addr);
m_copydata(m, offsetof(struct ip, ip_dst),
sizeof(struct in_addr),
&dst_address.sin.sin_addr);
break;
#endif
#ifdef INET6
case AF_INET6:
src_address.sin6.sin6_len = sizeof(struct sockaddr_in6);
dst_address.sin6.sin6_len = sizeof(struct sockaddr_in6);
m_copydata(m, offsetof(struct ip6_hdr, ip6_src),
sizeof(struct in6_addr),
&src_address.sin6.sin6_addr);
m_copydata(m, offsetof(struct ip6_hdr, ip6_dst),
sizeof(struct in6_addr),
&dst_address.sin6.sin6_addr);
if (sa6_recoverscope(&dst_address.sin6)) {
m_freem(m);
return EINVAL;
}
break;
#endif
default:
IPSECLOG(LOG_DEBUG, "unsupported protocol family %u\n", af);
m_freem(m);
IPSEC_ISTAT(sproto, ESP_STAT_NOPF, AH_STAT_NOPF,
IPCOMP_STAT_NOPF);
return EPFNOSUPPORT;
}
s = splsoftnet();
/* NB: only pass dst since key_lookup_sa follows RFC2401 */
sav = KEY_LOOKUP_SA(&dst_address, sproto, spi, sport, dport);
if (sav == NULL) {
static struct timeval lasttime = {0, 0};
static int curpps = 0;
if (!ipsec_debug && ppsratecheck(&lasttime, &curpps, 1)) {
if (sport || dport) {
log(LOG_INFO,
"no key association found for SA"
" %s[%u]-%s[%u]/SPI 0x%08lx\n",
ipsec_address(&src_address, buf, sizeof(buf)),
ntohs(sport),
ipsec_address(&dst_address, buf2, sizeof(buf2)),
ntohs(dport),
(u_long) ntohl(spi));
} else {
log(LOG_INFO,
"no key association found for"
" SA %s-%s/SPI 0x%08lx\n",
ipsec_address(&src_address, buf, sizeof(buf)),
ipsec_address(&src_address, buf2, sizeof(buf2)),
(u_long) ntohl(spi));
}
} else if (ipsec_debug) {
IPSECLOG(LOG_DEBUG,
"no key association found for SA "
"%s-%s/SPI 0x%08lx/PROTO %u/PORT %u-%u\n",
ipsec_address(&src_address, buf, sizeof(buf)),
ipsec_address(&dst_address, buf2, sizeof(buf2)),
(u_long) ntohl(spi), sproto, ntohs(dport), ntohs(sport));
}
IPSEC_ISTAT(sproto, ESP_STAT_NOTDB, AH_STAT_NOTDB,
IPCOMP_STAT_NOTDB);
splx(s);
m_freem(m);
return ENOENT;
}
KASSERT(sav->tdb_xform != NULL);
/*
* Call appropriate transform and return -- callback takes care of
* everything else.
*/
error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff);
KEY_SA_UNREF(&sav);
splx(s);
return error;
}
#ifdef INET
/*
* Common input handler for IPv4 AH, ESP, and IPCOMP.
*/
void
ipsec4_common_input(struct mbuf *m, int off, int proto)
{
(void)ipsec_common_input(m, off, offsetof(struct ip, ip_p),
AF_INET, proto);
}
/*
* IPsec input callback for INET protocols.
* This routine is called as the transform callback.
* Takes care of filtering and other sanity checks on
* the processed packet.
*/
int
ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav,
int skip, int protoff)
{
int prot, af __diagused, sproto;
struct ip *ip;
struct secasindex *saidx;
int error;
if (__predict_false(m == NULL)) {
panic("%s: NULL mbuf", __func__);
}
if (__predict_false(skip < sizeof(struct ip))) {
panic("%s: short skip", __func__);
}
KASSERT(sav != NULL);
saidx = &sav->sah->saidx;
af = saidx->dst.sa.sa_family;
KASSERTMSG(af == AF_INET, "unexpected af %u", af);
sproto = saidx->proto;
KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
sproto == IPPROTO_IPCOMP,
"unexpected security protocol %u", sproto);
/*
* Update the IPv4 header. The length of the packet may have changed,
* so fix it, and recompute the checksum.
*/
if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) {
char buf[IPSEC_ADDRSTRLEN];
cantpull:
IPSECLOG(LOG_DEBUG,
"processing failed for SA %s/%08lx\n",
ipsec_address(&sav->sah->saidx.dst, buf,
sizeof(buf)), (u_long) ntohl(sav->spi));
IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS,
IPCOMP_STAT_HDROPS);
error = ENOBUFS;
goto bad;
}
ip = mtod(m, struct ip *);
ip->ip_len = htons(m->m_pkthdr.len);
ip->ip_sum = 0;
ip->ip_sum = in_cksum(m, ip->ip_hl << 2);
/*
* Update TCP/UDP checksum
* XXX: should only do it in NAT-T case
* XXX: should do it incrementally, see FreeBSD code.
*/
m = ipsec4_fixup_checksum(m);
if (m == NULL)
goto cantpull;
ip = mtod(m, struct ip *);
prot = ip->ip_p;
M_VERIFY_PACKET(m);
key_sa_recordxfer(sav, m);
if ((inetsw[ip_protox[prot]].pr_flags & PR_LASTHDR) != 0 &&
ipsec_in_reject(m, NULL)) {
error = EINVAL;
goto bad;
}
/*
* There is no struct ifnet for tunnel mode IP-IP tunnel connecttion,
* so we cannot write filtering rule to the inner packet.
*/
if (saidx->mode == IPSEC_MODE_TUNNEL)
m->m_pkthdr.pkthdr_flags |= PKTHDR_FLAG_IPSEC_SKIP_PFIL;
(*inetsw[ip_protox[prot]].pr_input)(m, skip, prot);
return 0;
bad:
m_freem(m);
return error;
}
#endif /* INET */
#ifdef INET6
int
ipsec6_common_input(struct mbuf **mp, int *offp, int proto)
{
int l = 0;
int protoff, nxt;
struct ip6_ext ip6e;
if (*offp < sizeof(struct ip6_hdr)) {
IPSECLOG(LOG_DEBUG, "bad offset %u\n", *offp);
IPSEC_ISTAT(proto, ESP_STAT_HDROPS, AH_STAT_HDROPS,
IPCOMP_STAT_HDROPS);
m_freem(*mp);
return IPPROTO_DONE;
} else if (*offp == sizeof(struct ip6_hdr)) {
protoff = offsetof(struct ip6_hdr, ip6_nxt);
} else {
/* Chase down the header chain... */
protoff = sizeof(struct ip6_hdr);
nxt = (mtod(*mp, struct ip6_hdr *))->ip6_nxt;
do {
protoff += l;
m_copydata(*mp, protoff, sizeof(ip6e), &ip6e);
if (nxt == IPPROTO_AH)
l = (ip6e.ip6e_len + 2) << 2;
else if (nxt == IPPROTO_FRAGMENT)
l = sizeof(struct ip6_frag);
else
l = (ip6e.ip6e_len + 1) << 3;
KASSERT(l > 0);
nxt = ip6e.ip6e_nxt;
} while (protoff + l < *offp);
/* Malformed packet check */
if (protoff + l != *offp) {
IPSECLOG(LOG_DEBUG, "bad packet header chain, "
"protoff %u, l %u, off %u\n", protoff, l, *offp);
IPSEC_ISTAT(proto, ESP_STAT_HDROPS,
AH_STAT_HDROPS,
IPCOMP_STAT_HDROPS);
m_freem(*mp);
*mp = NULL;
return IPPROTO_DONE;
}
protoff += offsetof(struct ip6_ext, ip6e_nxt);
}
(void) ipsec_common_input(*mp, *offp, protoff, AF_INET6, proto);
return IPPROTO_DONE;
}
/*
* IPsec input callback, called by the transform callback. Takes care of
* filtering and other sanity checks on the processed packet.
*/
int
ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip,
int protoff)
{
int af __diagused, sproto;
struct ip6_hdr *ip6;
struct secasindex *saidx;
int nxt;
u_int8_t prot;
int error, nest;
if (__predict_false(m == NULL)) {
panic("%s: NULL mbuf", __func__);
}
KASSERT(sav != NULL);
saidx = &sav->sah->saidx;
af = saidx->dst.sa.sa_family;
KASSERTMSG(af == AF_INET6, "unexpected af %u", af);
sproto = saidx->proto;
KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
sproto == IPPROTO_IPCOMP,
"unexpected security protocol %u", sproto);
/* Fix IPv6 header */
if (m->m_len < sizeof(struct ip6_hdr) &&
(m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
char buf[IPSEC_ADDRSTRLEN];
IPSECLOG(LOG_DEBUG, "processing failed for SA %s/%08lx\n",
ipsec_address(&sav->sah->saidx.dst,
buf, sizeof(buf)), (u_long) ntohl(sav->spi));
IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS,
IPCOMP_STAT_HDROPS);
error = EACCES;
goto bad;
}
ip6 = mtod(m, struct ip6_hdr *);
ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr));
m_copydata(m, protoff, sizeof(prot), &prot);
key_sa_recordxfer(sav, m);
/*
* See the end of ip6_input for this logic.
* IPPROTO_IPV[46] case will be processed just like other ones
*/
nest = 0;
nxt = prot;
while (nxt != IPPROTO_DONE) {
if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) {
IP6_STATINC(IP6_STAT_TOOMANYHDR);
error = EINVAL;
goto bad;
}
M_VERIFY_PACKET(m);
/*
* Protection against faulty packet - there should be
* more sanity checks in header chain processing.
*/
if (m->m_pkthdr.len < skip) {
IP6_STATINC(IP6_STAT_TOOSHORT);
in6_ifstat_inc(m_get_rcvif_NOMPSAFE(m),
ifs6_in_truncated);
error = EINVAL;
goto bad;
}
/*
* Enforce IPsec policy checking if we are seeing last header.
* Note that we do not visit this with protocols with pcb layer
* code - like udp/tcp/raw ip.
*/
if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
ipsec_in_reject(m, NULL)) {
error = EINVAL;
goto bad;
}
/*
* There is no struct ifnet for tunnel mode IP-IP tunnel connecttion,
* so we cannot write filtering rule to the inner packet.
*/
if (saidx->mode == IPSEC_MODE_TUNNEL)
m->m_pkthdr.pkthdr_flags |= PKTHDR_FLAG_IPSEC_SKIP_PFIL;
nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt);
}
return 0;
bad:
if (m)
m_freem(m);
return error;
}
#endif /* INET6 */