text: /*	$FreeBSD$	*/
  /*	$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.
   */
  
  /*
   * IPsec input processing.
   */
  
  #include "opt_inet.h"
  #include "opt_inet6.h"
  #include "opt_ipsec.h"
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/malloc.h>
  #include <sys/mbuf.h>
  #include <sys/domain.h>
  #include <sys/protosw.h>
  #include <sys/socket.h>
  #include <sys/errno.h>
  #include <sys/hhook.h>
  #include <sys/syslog.h>
  
  #include <net/if.h>
  #include <net/if_var.h>
  #include <net/if_enc.h>
  #include <net/netisr.h>
  #include <net/vnet.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>
  #ifdef INET6
  #include <netinet6/ip6_var.h>
  #endif
  #include <netinet/in_pcb.h>
  #ifdef INET6
  #include <netinet/icmp6.h>
  #endif
  
  #include <netipsec/ipsec.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>
  
  #include <machine/in_cksum.h>
  #include <machine/stdarg.h>
  
  
  #define	IPSEC_ISTAT(proto, name)	do {	\
  	if ((proto) == IPPROTO_ESP)		\
  		ESPSTAT_INC(esps_##name);	\
  	else if ((proto) == IPPROTO_AH)		\
  		AHSTAT_INC(ahs_##name);		\
  	else					\
  		IPCOMPSTAT_INC(ipcomps_##name);	\
  } while (0)
  
  #ifdef INET
  static void ipsec4_common_ctlinput(int, struct sockaddr *, void *, int);
  #endif
  
  /*
   * 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).
   */
  int
  ipsec_common_input(struct mbuf *m, int skip, int protoff, int af, int sproto)
  {
  	char buf[INET6_ADDRSTRLEN];
  	union sockaddr_union dst_address;
  	struct secasvar *sav;
  	u_int32_t spi;
  	int error;
  #ifdef INET
  #ifdef IPSEC_NAT_T
  	struct m_tag *tag;
  #endif
  #endif
  
  	IPSEC_ISTAT(sproto, input);
  
  	IPSEC_ASSERT(m != NULL, ("null packet"));
  
  	IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
  		sproto == IPPROTO_IPCOMP,
  		("unexpected security protocol %u", sproto));
  
  	if ((sproto == IPPROTO_ESP && !V_esp_enable) ||
  	    (sproto == IPPROTO_AH && !V_ah_enable) ||
  	    (sproto == IPPROTO_IPCOMP && !V_ipcomp_enable)) {
  		m_freem(m);
  		IPSEC_ISTAT(sproto, pdrops);
  		return EOPNOTSUPP;
  	}
  
  	if (m->m_pkthdr.len - skip < 2 * sizeof (u_int32_t)) {
  		m_freem(m);
  		IPSEC_ISTAT(sproto, hdrops);
  		DPRINTF(("%s: packet too small\n", __func__));
  		return EINVAL;
  	}
  
  	/* Retrieve the SPI from the relevant IPsec header */
  	if (sproto == IPPROTO_ESP)
  		m_copydata(m, skip, sizeof(u_int32_t), (caddr_t) &spi);
  	else if (sproto == IPPROTO_AH)
  		m_copydata(m, skip + sizeof(u_int32_t), sizeof(u_int32_t),
  		    (caddr_t) &spi);
  	else if (sproto == IPPROTO_IPCOMP) {
  		u_int16_t cpi;
  		m_copydata(m, skip + sizeof(u_int16_t), sizeof(u_int16_t),
  		    (caddr_t) &cpi);
  		spi = ntohl(htons(cpi));
  	}
  
  	/*
  	 * 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.
  	 */
  	bzero(&dst_address, sizeof (dst_address));
  	dst_address.sa.sa_family = af;
  	switch (af) {
  #ifdef INET
  	case AF_INET:
  		dst_address.sin.sin_len = sizeof(struct sockaddr_in);
  		m_copydata(m, offsetof(struct ip, ip_dst),
  		    sizeof(struct in_addr),
  		    (caddr_t) &dst_address.sin.sin_addr);
  #ifdef IPSEC_NAT_T
  		/* Find the source port for NAT-T; see udp*_espdecap. */
  		tag = m_tag_find(m, PACKET_TAG_IPSEC_NAT_T_PORTS, NULL);
  		if (tag != NULL)
  			dst_address.sin.sin_port = ((u_int16_t *)(tag + 1))[1];
  #endif /* IPSEC_NAT_T */
  		break;
  #endif /* INET */
  #ifdef INET6
  	case AF_INET6:
  		dst_address.sin6.sin6_len = sizeof(struct sockaddr_in6);
  		m_copydata(m, offsetof(struct ip6_hdr, ip6_dst),
  		    sizeof(struct in6_addr),
  		    (caddr_t) &dst_address.sin6.sin6_addr);
  		/* We keep addresses in SADB without embedded scope id */
  		if (IN6_IS_SCOPE_LINKLOCAL(&dst_address.sin6.sin6_addr)) {
  			/* XXX: sa6_recoverscope() */
  			dst_address.sin6.sin6_scope_id =
  			    ntohs(dst_address.sin6.sin6_addr.s6_addr16[1]);
  			dst_address.sin6.sin6_addr.s6_addr16[1] = 0;
  		}
  		break;
  #endif /* INET6 */
  	default:
  		DPRINTF(("%s: unsupported protocol family %u\n", __func__, af));
  		m_freem(m);
  		IPSEC_ISTAT(sproto, nopf);
  		return EPFNOSUPPORT;
  	}
  
  	/* NB: only pass dst since key_allocsa follows RFC2401 */
  	sav = KEY_ALLOCSA(&dst_address, sproto, spi);
  	if (sav == NULL) {
  		DPRINTF(("%s: no key association found for SA %s/%08lx/%u\n",
  		    __func__, ipsec_address(&dst_address, buf, sizeof(buf)),
  		    (u_long) ntohl(spi), sproto));
  		IPSEC_ISTAT(sproto, notdb);
  		m_freem(m);
  		return ENOENT;
  	}
  
  	if (sav->tdb_xform == NULL) {
  		DPRINTF(("%s: attempted to use uninitialized SA %s/%08lx/%u\n",
  		    __func__, ipsec_address(&dst_address, buf, sizeof(buf)),
  		    (u_long) ntohl(spi), sproto));
  		IPSEC_ISTAT(sproto, noxform);
  		KEY_FREESAV(&sav);
  		m_freem(m);
  		return ENXIO;
  	}
  
  	/*
  	 * Call appropriate transform and return -- callback takes care of
  	 * everything else.
  	 */
  	error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff);
  	KEY_FREESAV(&sav);
  	return error;
  }
  
  #ifdef INET
  int
  ah4_input(struct mbuf **mp, int *offp, int proto)
  {
  	struct mbuf *m;
  	int off;
  
  	m = *mp;
  	off = *offp;
  	*mp = NULL;
  
  	ipsec_common_input(m, off, offsetof(struct ip, ip_p),
  				AF_INET, IPPROTO_AH);
  	return (IPPROTO_DONE);
  }
  void
  ah4_ctlinput(int cmd, struct sockaddr *sa, void *v)
  {
  	if (sa->sa_family == AF_INET &&
  	    sa->sa_len == sizeof(struct sockaddr_in))
  		ipsec4_common_ctlinput(cmd, sa, v, IPPROTO_AH);
  }
  
  int
  esp4_input(struct mbuf **mp, int *offp, int proto)
  {
  	struct mbuf *m;
  	int off;
  
  	m = *mp;
  	off = *offp;
  	mp = NULL;
  
  	ipsec_common_input(m, off, offsetof(struct ip, ip_p),
  				AF_INET, IPPROTO_ESP);
  	return (IPPROTO_DONE);
  }
  
  void
  esp4_ctlinput(int cmd, struct sockaddr *sa, void *v)
  {
  	if (sa->sa_family == AF_INET &&
  	    sa->sa_len == sizeof(struct sockaddr_in))
  		ipsec4_common_ctlinput(cmd, sa, v, IPPROTO_ESP);
  }
  
  int
  ipcomp4_input(struct mbuf **mp, int *offp, int proto)
  {
  	struct mbuf *m;
  	int off;
  
  	m = *mp;
  	off = *offp;
  	mp = NULL;
  
  	ipsec_common_input(m, off, offsetof(struct ip, ip_p),
  				AF_INET, IPPROTO_IPCOMP);
  	return (IPPROTO_DONE);
  }
  
  /*
   * 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)
  {
  	char buf[INET6_ADDRSTRLEN];
  	struct ipsec_ctx_data ctx;
  	int prot, af, sproto, isr_prot;
  	struct ip *ip;
  	struct m_tag *mtag;
  	struct tdb_ident *tdbi;
  	struct secasindex *saidx;
  	int error;
  #ifdef INET6
  #ifdef notyet
  	char ip6buf[INET6_ADDRSTRLEN];
  #endif
  #endif
  
  	IPSEC_ASSERT(m != NULL, ("null mbuf"));
  	IPSEC_ASSERT(sav != NULL, ("null SA"));
  	IPSEC_ASSERT(sav->sah != NULL, ("null SAH"));
  	saidx = &sav->sah->saidx;
  	af = saidx->dst.sa.sa_family;
  	IPSEC_ASSERT(af == AF_INET, ("unexpected af %u", af));
  	sproto = saidx->proto;
  	IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
  		sproto == IPPROTO_IPCOMP,
  		("unexpected security protocol %u", sproto));
  
  	/* Sanity check */
  	if (m == NULL) {
  		DPRINTF(("%s: null mbuf", __func__));
  		IPSEC_ISTAT(sproto, badkcr);
  		KEY_FREESAV(&sav);
  		return EINVAL;
  	}
  
  	if (skip != 0) {
  		/*
  		 * Fix IPv4 header
  		 * XXXGL: do we need this entire block?
  		 */
  		if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) {
  			DPRINTF(("%s: processing failed for SA %s/%08lx\n",
  			    __func__, ipsec_address(&sav->sah->saidx.dst,
  			    buf, sizeof(buf)), (u_long) ntohl(sav->spi)));
  			IPSEC_ISTAT(sproto, 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);
  	} else {
  		ip = mtod(m, struct ip *);
  	}
  	prot = ip->ip_p;
  
  	IPSEC_INIT_CTX(&ctx, &m, sav, AF_INET, IPSEC_ENC_BEFORE);
  	if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0)
  		goto bad;
  	ip = mtod(m, struct ip *);
  
  	/* IP-in-IP encapsulation */
  	if (prot == IPPROTO_IPIP &&
  	    saidx->mode != IPSEC_MODE_TRANSPORT) {
  
  		if (m->m_pkthdr.len - skip < sizeof(struct ip)) {
  			IPSEC_ISTAT(sproto, hdrops);
  			error = EINVAL;
  			goto bad;
  		}
  		/* enc0: strip outer IPv4 header */
  		m_striphdr(m, 0, ip->ip_hl << 2);
  
  #ifdef notyet
  		/* XXX PROXY address isn't recorded in SAH */
  		/*
  		 * Check that the inner source address is the same as
  		 * the proxy address, if available.
  		 */
  		if ((saidx->proxy.sa.sa_family == AF_INET &&
  		    saidx->proxy.sin.sin_addr.s_addr !=
  		    INADDR_ANY &&
  		    ipn.ip_src.s_addr !=
  		    saidx->proxy.sin.sin_addr.s_addr) ||
  		    (saidx->proxy.sa.sa_family != AF_INET &&
  			saidx->proxy.sa.sa_family != 0)) {
  
  			DPRINTF(("%s: inner source address %s doesn't "
  			    "correspond to expected proxy source %s, "
  			    "SA %s/%08lx\n", __func__,
  			    inet_ntoa4(ipn.ip_src),
  			    ipsp_address(saidx->proxy),
  			    ipsp_address(saidx->dst),
  			    (u_long) ntohl(sav->spi)));
  
  			IPSEC_ISTAT(sproto, pdrops);
  			error = EACCES;
  			goto bad;
  		}
  #endif /* notyet */
  	}
  #ifdef INET6
  	/* IPv6-in-IP encapsulation. */
  	else if (prot == IPPROTO_IPV6 &&
  	    saidx->mode != IPSEC_MODE_TRANSPORT) {
  
  		if (m->m_pkthdr.len - skip < sizeof(struct ip6_hdr)) {
  			IPSEC_ISTAT(sproto, hdrops);
  			error = EINVAL;
  			goto bad;
  		}
  		/* enc0: strip IPv4 header, keep IPv6 header only */
  		m_striphdr(m, 0, ip->ip_hl << 2);
  #ifdef notyet 
  		/*
  		 * Check that the inner source address is the same as
  		 * the proxy address, if available.
  		 */
  		if ((saidx->proxy.sa.sa_family == AF_INET6 &&
  		    !IN6_IS_ADDR_UNSPECIFIED(&saidx->proxy.sin6.sin6_addr) &&
  		    !IN6_ARE_ADDR_EQUAL(&ip6n.ip6_src,
  			&saidx->proxy.sin6.sin6_addr)) ||
  		    (saidx->proxy.sa.sa_family != AF_INET6 &&
  			saidx->proxy.sa.sa_family != 0)) {
  
  			DPRINTF(("%s: inner source address %s doesn't "
  			    "correspond to expected proxy source %s, "
  			    "SA %s/%08lx\n", __func__,
  			    ip6_sprintf(ip6buf, &ip6n.ip6_src),
  			    ipsec_address(&saidx->proxy),
  			    ipsec_address(&saidx->dst),
  			    (u_long) ntohl(sav->spi)));
  
  			IPSEC_ISTAT(sproto, pdrops);
  			error = EACCES;
  			goto bad;
  		}
  #endif /* notyet */
  	}
  #endif /* INET6 */
  	else if (prot != IPPROTO_IPV6 && saidx->mode == IPSEC_MODE_ANY) {
  		/*
  		 * When mode is wildcard, inner protocol is IPv6 and
  		 * we have no INET6 support - drop this packet a bit later.
  		 * In other cases we assume transport mode and outer
  		 * header was already stripped in xform_xxx_cb.
  		 */
  		prot = IPPROTO_IPIP;
  	}
  
  	/*
  	 * Record what we've done to the packet (under what SA it was
  	 * processed).
  	 */
  	if (sproto != IPPROTO_IPCOMP) {
  		mtag = m_tag_get(PACKET_TAG_IPSEC_IN_DONE,
  		    sizeof(struct tdb_ident), M_NOWAIT);
  		if (mtag == NULL) {
  			DPRINTF(("%s: failed to get tag\n", __func__));
  			IPSEC_ISTAT(sproto, hdrops);
  			error = ENOMEM;
  			goto bad;
  		}
  
  		tdbi = (struct tdb_ident *)(mtag + 1);
  		bcopy(&saidx->dst, &tdbi->dst, saidx->dst.sa.sa_len);
  		tdbi->proto = sproto;
  		tdbi->spi = sav->spi;
  		/* Cache those two for enc(4) in xform_ipip. */
  		tdbi->alg_auth = sav->alg_auth;
  		tdbi->alg_enc = sav->alg_enc;
  
  		m_tag_prepend(m, mtag);
  	}
  
  	key_sa_recordxfer(sav, m);		/* record data transfer */
  
  	/*
  	 * In transport mode requeue decrypted mbuf back to IPv4 protocol
  	 * handler. This is necessary to correctly expose rcvif.
  	 */
  	if (saidx->mode == IPSEC_MODE_TRANSPORT)
  		prot = IPPROTO_IPIP;
  	/*
  	 * Re-dispatch via software interrupt.
  	 */
  	switch (prot) {
  	case IPPROTO_IPIP:
  		isr_prot = NETISR_IP;
  		af = AF_INET;
  		break;
  #ifdef INET6
  	case IPPROTO_IPV6:
  		isr_prot = NETISR_IPV6;
  		af = AF_INET6;
  		break;
  #endif
  	default:
  		DPRINTF(("%s: cannot handle inner ip proto %d\n",
  			    __func__, prot));
  		IPSEC_ISTAT(sproto, nopf);
  		error = EPFNOSUPPORT;
  		goto bad;
  	}
  
  	IPSEC_INIT_CTX(&ctx, &m, sav, af, IPSEC_ENC_AFTER);
  	if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0)
  		goto bad;
  	error = netisr_queue_src(isr_prot, (uintptr_t)sav->spi, m);
  	if (error) {
  		IPSEC_ISTAT(sproto, qfull);
  		DPRINTF(("%s: queue full; proto %u packet dropped\n",
  			__func__, sproto));
  		return error;
  	}
  	return 0;
  bad:
  	m_freem(m);
  	return error;
  }
  
  void
  ipsec4_common_ctlinput(int cmd, struct sockaddr *sa, void *v, int proto)
  {
  	/* XXX nothing just yet */
  }
  #endif /* INET */
  
  #ifdef INET6
  /* IPv6 AH wrapper. */
  int
  ipsec6_common_input(struct mbuf **mp, int *offp, int proto)
  {
  	int l = 0;
  	int protoff;
  	struct ip6_ext ip6e;
  
  	if (*offp < sizeof(struct ip6_hdr)) {
  		DPRINTF(("%s: bad offset %u\n", __func__, *offp));
  		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);
  
  		do {
  			protoff += l;
  			m_copydata(*mp, protoff, sizeof(ip6e),
  			    (caddr_t) &ip6e);
  
  			if (ip6e.ip6e_nxt == IPPROTO_AH)
  				l = (ip6e.ip6e_len + 2) << 2;
  			else
  				l = (ip6e.ip6e_len + 1) << 3;
  			IPSEC_ASSERT(l > 0, ("l went zero or negative"));
  		} while (protoff + l < *offp);
  
  		/* Malformed packet check */
  		if (protoff + l != *offp) {
  			DPRINTF(("%s: bad packet header chain, protoff %u, "
  				"l %u, off %u\n", __func__, protoff, l, *offp));
  			IPSEC_ISTAT(proto, 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)
  {
  	char buf[INET6_ADDRSTRLEN];
  	struct ipsec_ctx_data ctx;
  	int prot, af, sproto;
  	struct ip6_hdr *ip6;
  	struct m_tag *mtag;
  	struct tdb_ident *tdbi;
  	struct secasindex *saidx;
  	int nxt, isr_prot;
  	u_int8_t nxt8;
  	int error, nest;
  #ifdef notyet
  	char ip6buf[INET6_ADDRSTRLEN];
  #endif
  
  	IPSEC_ASSERT(m != NULL, ("null mbuf"));
  	IPSEC_ASSERT(sav != NULL, ("null SA"));
  	IPSEC_ASSERT(sav->sah != NULL, ("null SAH"));
  	saidx = &sav->sah->saidx;
  	af = saidx->dst.sa.sa_family;
  	IPSEC_ASSERT(af == AF_INET6, ("unexpected af %u", af));
  	sproto = saidx->proto;
  	IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
  		sproto == IPPROTO_IPCOMP,
  		("unexpected security protocol %u", sproto));
  
  	/* Sanity check */
  	if (m == NULL) {
  		DPRINTF(("%s: null mbuf", __func__));
  		IPSEC_ISTAT(sproto, badkcr);
  		error = EINVAL;
  		goto bad;
  	}
  
  	/* Fix IPv6 header */
  	if (m->m_len < sizeof(struct ip6_hdr) &&
  	    (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
  
  		DPRINTF(("%s: processing failed for SA %s/%08lx\n",
  		    __func__, ipsec_address(&sav->sah->saidx.dst, buf,
  		    sizeof(buf)), (u_long) ntohl(sav->spi)));
  
  		IPSEC_ISTAT(sproto, hdrops);
  		error = EACCES;
  		goto bad;
  	}
  
  	ip6 = mtod(m, struct ip6_hdr *);
  	ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr));
  
  	IPSEC_INIT_CTX(&ctx, &m, sav, af, IPSEC_ENC_BEFORE);
  	if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0)
  		goto bad;
  	/* Save protocol */
  	m_copydata(m, protoff, 1, &nxt8);
  	prot = nxt8;
  
  	/* IPv6-in-IP encapsulation */
  	if (prot == IPPROTO_IPV6 &&
  	    saidx->mode != IPSEC_MODE_TRANSPORT) {
  		if (m->m_pkthdr.len - skip < sizeof(struct ip6_hdr)) {
  			IPSEC_ISTAT(sproto, hdrops);
  			error = EINVAL;
  			goto bad;
  		}
  		/* ip6n will now contain the inner IPv6 header. */
  		m_striphdr(m, 0, skip);
  		skip = 0;
  #ifdef notyet
  		/*
  		 * Check that the inner source address is the same as
  		 * the proxy address, if available.
  		 */
  		if ((saidx->proxy.sa.sa_family == AF_INET6 &&
  		    !IN6_IS_ADDR_UNSPECIFIED(&saidx->proxy.sin6.sin6_addr) &&
  		    !IN6_ARE_ADDR_EQUAL(&ip6n.ip6_src,
  			&saidx->proxy.sin6.sin6_addr)) ||
  		    (saidx->proxy.sa.sa_family != AF_INET6 &&
  			saidx->proxy.sa.sa_family != 0)) {
  
  			DPRINTF(("%s: inner source address %s doesn't "
  			    "correspond to expected proxy source %s, "
  			    "SA %s/%08lx\n", __func__,
  			    ip6_sprintf(ip6buf, &ip6n.ip6_src),
  			    ipsec_address(&saidx->proxy),
  			    ipsec_address(&saidx->dst),
  			    (u_long) ntohl(sav->spi)));
  
  			IPSEC_ISTAT(sproto, pdrops);
  			error = EACCES;
  			goto bad;
  		}
  #endif /* notyet */
  	}
  #ifdef INET
  	/* IP-in-IP encapsulation */
  	else if (prot == IPPROTO_IPIP &&
  	    saidx->mode != IPSEC_MODE_TRANSPORT) {
  		if (m->m_pkthdr.len - skip < sizeof(struct ip)) {
  			IPSEC_ISTAT(sproto, hdrops);
  			error = EINVAL;
  			goto bad;
  		}
  		/* ipn will now contain the inner IPv4 header */
  	 	m_striphdr(m, 0, skip);
  		skip = 0;
  #ifdef notyet
  		/*
  		 * Check that the inner source address is the same as
  		 * the proxy address, if available.
  		 */
  		if ((saidx->proxy.sa.sa_family == AF_INET &&
  		    saidx->proxy.sin.sin_addr.s_addr != INADDR_ANY &&
  		    ipn.ip_src.s_addr != saidx->proxy.sin.sin_addr.s_addr) ||
  		    (saidx->proxy.sa.sa_family != AF_INET &&
  			saidx->proxy.sa.sa_family != 0)) {
  
  			DPRINTF(("%s: inner source address %s doesn't "
  			    "correspond to expected proxy source %s, "
  			    "SA %s/%08lx\n", __func__,
  			    inet_ntoa4(ipn.ip_src),
  			    ipsec_address(&saidx->proxy),
  			    ipsec_address(&saidx->dst),
  			    (u_long) ntohl(sav->spi)));
  
  			IPSEC_ISTAT(sproto, pdrops);
  			error = EACCES;
  			goto bad;
  		}
  #endif /* notyet */
  	}
  #endif /* INET */
  	else {
  		prot = IPPROTO_IPV6; /* for correct BPF processing */
  	}
  
  	/*
  	 * Record what we've done to the packet (under what SA it was
  	 * processed).
  	 */
  	if (sproto != IPPROTO_IPCOMP) {
  		mtag = m_tag_get(PACKET_TAG_IPSEC_IN_DONE,
  		    sizeof(struct tdb_ident), M_NOWAIT);
  		if (mtag == NULL) {
  			DPRINTF(("%s: failed to get tag\n", __func__));
  			IPSEC_ISTAT(sproto, hdrops);
  			error = ENOMEM;
  			goto bad;
  		}
  
  		tdbi = (struct tdb_ident *)(mtag + 1);
  		bcopy(&saidx->dst, &tdbi->dst, sizeof(union sockaddr_union));
  		tdbi->proto = sproto;
  		tdbi->spi = sav->spi;
  		/* Cache those two for enc(4) in xform_ipip. */
  		tdbi->alg_auth = sav->alg_auth;
  		tdbi->alg_enc = sav->alg_enc;
  
  		m_tag_prepend(m, mtag);
  	}
  
  	key_sa_recordxfer(sav, m);
  
  
  #ifdef INET
  	if (prot == IPPROTO_IPIP)
  		af = AF_INET;
  	else
  #endif
  		af = AF_INET6;
  	IPSEC_INIT_CTX(&ctx, &m, sav, af, IPSEC_ENC_AFTER);
  	if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0)
  		goto bad;
  	if (skip == 0) {
  		/*
  		 * We stripped outer IPv6 header.
  		 * Now we should requeue decrypted packet via netisr.
  		 */
  		switch (prot) {
  #ifdef INET
  		case IPPROTO_IPIP:
  			isr_prot = NETISR_IP;
  			break;
  #endif
  		case IPPROTO_IPV6:
  			isr_prot = NETISR_IPV6;
  			break;
  		default:
  			DPRINTF(("%s: cannot handle inner ip proto %d\n",
  			    __func__, prot));
  			IPSEC_ISTAT(sproto, nopf);
  			error = EPFNOSUPPORT;
  			goto bad;
  		}
  		error = netisr_queue_src(isr_prot, (uintptr_t)sav->spi, m);
  		if (error) {
  			IPSEC_ISTAT(sproto, qfull);
  			DPRINTF(("%s: queue full; proto %u packet dropped\n",
  			    __func__, sproto));
  		}
  		return (error);
  	}
  	/*
  	 * See the end of ip6_input for this logic.
  	 * IPPROTO_IPV[46] case will be processed just like other ones
  	 */
  	nest = 0;
  	nxt = nxt8;
  	while (nxt != IPPROTO_DONE) {
  		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
  			IP6STAT_INC(ip6s_toomanyhdr);
  			error = EINVAL;
  			goto bad;
  		}
  
  		/*
  		 * Protection against faulty packet - there should be
  		 * more sanity checks in header chain processing.
  		 */
  		if (m->m_pkthdr.len < skip) {
  			IP6STAT_INC(ip6s_tooshort);
  			in6_ifstat_inc(m->m_pkthdr.rcvif, 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 &&
  		    ipsec6_in_reject(m, NULL)) {
  			error = EINVAL;
  			goto bad;
  		}
  		nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt);
  	}
  	return 0;
  bad:
  	if (m)
  		m_freem(m);
  	return error;
  }
  
  void
  esp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
  {
  	struct ip6ctlparam *ip6cp = NULL;
  	struct mbuf *m = NULL;
  	struct ip6_hdr *ip6;
  	int off;
  
  	if (sa->sa_family != AF_INET6 ||
  	    sa->sa_len != sizeof(struct sockaddr_in6))
  		return;
  	if ((unsigned)cmd >= PRC_NCMDS)
  		return;
  
  	/* if the parameter is from icmp6, decode it. */
  	if (d != NULL) {
  		ip6cp = (struct ip6ctlparam *)d;
  		m = ip6cp->ip6c_m;
  		ip6 = ip6cp->ip6c_ip6;
  		off = ip6cp->ip6c_off;
  	} else {
  		m = NULL;
  		ip6 = NULL;
  		off = 0;	/* calm gcc */
  	}
  
  	if (ip6 != NULL) {
  
  		struct ip6ctlparam ip6cp1;
  
  		/*
  		 * Notify the error to all possible sockets via pfctlinput2.
  		 * Since the upper layer information (such as protocol type,
  		 * source and destination ports) is embedded in the encrypted
  		 * data and might have been cut, we can't directly call
  		 * an upper layer ctlinput function. However, the pcbnotify
  		 * function will consider source and destination addresses
  		 * as well as the flow info value, and may be able to find
  		 * some PCB that should be notified.
  		 * Although pfctlinput2 will call esp6_ctlinput(), there is
  		 * no possibility of an infinite loop of function calls,
  		 * because we don't pass the inner IPv6 header.
  		 */
  		bzero(&ip6cp1, sizeof(ip6cp1));
  		ip6cp1.ip6c_src = ip6cp->ip6c_src;
  		pfctlinput2(cmd, sa, (void *)&ip6cp1);
  
  		/*
  		 * Then go to special cases that need ESP header information.
  		 * XXX: We assume that when ip6 is non NULL,
  		 * M and OFF are valid.
  		 */
  
  		if (cmd == PRC_MSGSIZE) {
  			struct secasvar *sav;
  			u_int32_t spi;
  			int valid;
  
  			/* check header length before using m_copydata */
  			if (m->m_pkthdr.len < off + sizeof (struct esp))
  				return;
  			m_copydata(m, off + offsetof(struct esp, esp_spi),
  				sizeof(u_int32_t), (caddr_t) &spi);
  			/*
  			 * Check to see if we have a valid SA corresponding to
  			 * the address in the ICMP message payload.
  			 */
  			sav = KEY_ALLOCSA((union sockaddr_union *)sa,
  					IPPROTO_ESP, spi);
  			valid = (sav != NULL);
  			if (sav)
  				KEY_FREESAV(&sav);
  
  			/* XXX Further validation? */
  
  			/*
  			 * Depending on whether the SA is "valid" and
  			 * routing table size (mtudisc_{hi,lo}wat), we will:
  			 * - recalcurate the new MTU and create the
  			 *   corresponding routing entry, or
  			 * - ignore the MTU change notification.
  			 */
  			icmp6_mtudisc_update(ip6cp, valid);
  		}
  	} else {
  		/* we normally notify any pcb here */
  	}
  }
  #endif /* INET6 */
  