/*	$OpenBSD: ip_ah.c,v 1.79 2003/08/14 19:00:12 jason 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 and Niklas Hallqvist.
 *
 * Copyright (c) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
 * Angelos D. Keromytis and Niels Provos.
 * Copyright (c) 1999 Niklas Hallqvist.
 * 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/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socket.h>

#include <net/if.h>
#include <net/bpf.h>

#ifdef INET
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#endif /* INET */

#ifdef INET6
#ifndef INET
#include <netinet/in.h>
#endif /* INET */
#include <netinet/ip6.h>
#endif /* INET6 */

#include <netinet/ip_ipsp.h>
#include <netinet/ip_ah.h>
#include <net/pfkeyv2.h>
#include <net/if_enc.h>

#include <crypto/cryptodev.h>
#include <crypto/xform.h>

#include "bpfilter.h"

#ifdef ENCDEBUG
#define DPRINTF(x)	if (encdebug) printf x
#else
#define DPRINTF(x)
#endif

struct ahstat ahstat;

/*
 * ah_attach() is called from the transformation initialization code.
 */
int
ah_attach()
{
	return 0;
}

/*
 * ah_init() is called when an SPI is being set up.
 */
int
ah_init(struct tdb *tdbp, struct xformsw *xsp, struct ipsecinit *ii)
{
	struct auth_hash *thash = NULL;
	struct cryptoini cria;

	/* Authentication operation. */
	switch (ii->ii_authalg) {
	case SADB_AALG_MD5HMAC:
		thash = &auth_hash_hmac_md5_96;
		break;

	case SADB_AALG_SHA1HMAC:
		thash = &auth_hash_hmac_sha1_96;
		break;

	case SADB_X_AALG_RIPEMD160HMAC:
		thash = &auth_hash_hmac_ripemd_160_96;
		break;

	case SADB_X_AALG_SHA2_256:
		thash = &auth_hash_hmac_sha2_256_96;
		break;

	case SADB_X_AALG_SHA2_384:
		thash = &auth_hash_hmac_sha2_384_96;
		break;

	case SADB_X_AALG_SHA2_512:
		thash = &auth_hash_hmac_sha2_512_96;
		break;

	case SADB_X_AALG_MD5:
		thash = &auth_hash_key_md5;
		break;

	case SADB_X_AALG_SHA1:
		thash = &auth_hash_key_sha1;
		break;

	default:
		DPRINTF(("ah_init(): unsupported authentication algorithm %d specified\n", ii->ii_authalg));
		return EINVAL;
	}

	if (ii->ii_authkeylen != thash->keysize && thash->keysize != 0) {
		DPRINTF(("ah_init(): keylength %d doesn't match algorithm "
		    "%s keysize (%d)\n", ii->ii_authkeylen, thash->name,
		    thash->keysize));
		return EINVAL;
	}

	tdbp->tdb_xform = xsp;
	tdbp->tdb_authalgxform = thash;
	tdbp->tdb_bitmap = 0;
	tdbp->tdb_rpl = AH_HMAC_INITIAL_RPL;

	DPRINTF(("ah_init(): initialized TDB with hash algorithm %s\n",
	    thash->name));

	tdbp->tdb_amxkeylen = ii->ii_authkeylen;
	MALLOC(tdbp->tdb_amxkey, u_int8_t *, tdbp->tdb_amxkeylen, M_XDATA,
	    M_WAITOK);

	bcopy(ii->ii_authkey, tdbp->tdb_amxkey, tdbp->tdb_amxkeylen);

	/* Initialize crypto session. */
	bzero(&cria, sizeof(cria));
	cria.cri_alg = tdbp->tdb_authalgxform->type;
	cria.cri_klen = ii->ii_authkeylen * 8;
	cria.cri_key = ii->ii_authkey;

	return crypto_newsession(&tdbp->tdb_cryptoid, &cria, 0);
}

/*
 * Paranoia.
 */
int
ah_zeroize(struct tdb *tdbp)
{
	int err;

	if (tdbp->tdb_amxkey) {
		bzero(tdbp->tdb_amxkey, tdbp->tdb_amxkeylen);
		FREE(tdbp->tdb_amxkey, M_XDATA);
		tdbp->tdb_amxkey = NULL;
	}

	err = crypto_freesession(tdbp->tdb_cryptoid);
	tdbp->tdb_cryptoid = 0;
	return err;
}

/*
 * Massage IPv4/IPv6 headers for AH processing.
 */
int
ah_massage_headers(struct mbuf **m0, int proto, int skip, int alg, int out)
{
	struct mbuf *m = *m0;
	unsigned char *ptr;
	int off, count;

#ifdef INET
	struct ip *ip;
#endif /* INET */

#ifdef INET6
	struct ip6_ext *ip6e;
	struct ip6_hdr ip6;
	int alloc, len, ad;
#endif /* INET6 */

	switch (proto) {
#ifdef INET
	case AF_INET:
		/*
		 * This is the least painful way of dealing with IPv4 header
		 * and option processing -- just make sure they're in
		 * contiguous memory.
		 */
		*m0 = m = m_pullup(m, skip);
		if (m == NULL) {
			DPRINTF(("ah_massage_headers(): m_pullup() failed\n"));
			ahstat.ahs_hdrops++;
			return ENOBUFS;
		}

		/* Fix the IP header */
		ip = mtod(m, struct ip *);
		ip->ip_tos = 0;
		ip->ip_ttl = 0;
		ip->ip_sum = 0;

		/*
		 * On input, fix ip_len which has been byte-swapped
		 * at ip_input().
		 */
		if (alg == CRYPTO_MD5_KPDK || alg == CRYPTO_SHA1_KPDK)
			ip->ip_off &= htons(IP_DF);
		else
			ip->ip_off = 0;

		ptr = mtod(m, unsigned char *) + sizeof(struct ip);

		/* IPv4 option processing */
		for (off = sizeof(struct ip); off < skip;) {
			if (ptr[off] == IPOPT_EOL || ptr[off] == IPOPT_NOP ||
			    off + 1 < skip)
				;
			else {
				DPRINTF(("ah_massage_headers(): illegal IPv4 "
				    "option length for option %d\n",
				    ptr[off]));

				ahstat.ahs_hdrops++;
				m_freem(m);
				return EINVAL;
			}

			switch (ptr[off]) {
			case IPOPT_EOL:
				off = skip;  /* End the loop. */
				break;

			case IPOPT_NOP:
				off++;
				break;

			case IPOPT_SECURITY:	/* 0x82 */
			case 0x85:	/* Extended security. */
			case 0x86:	/* Commercial security. */
			case 0x94:	/* Router alert */
			case 0x95:	/* RFC1770 */
				/* Sanity check for option length. */
				if (ptr[off + 1] < 2) {
					DPRINTF(("ah_massage_headers(): "
					    "illegal IPv4 option length for "
					    "option %d\n", ptr[off]));

					ahstat.ahs_hdrops++;
					m_freem(m);
					return EINVAL;
				}

				off += ptr[off + 1];
				break;

			case IPOPT_LSRR:
			case IPOPT_SSRR:
				/* Sanity check for option length. */
				if (ptr[off + 1] < 2) {
					DPRINTF(("ah_massage_headers(): "
					    "illegal IPv4 option length for "
					    "option %d\n", ptr[off]));

					ahstat.ahs_hdrops++;
					m_freem(m);
					return EINVAL;
				}

				/*
				 * On output, if we have either of the
				 * source routing options, we should
				 * swap the destination address of the
				 * IP header with the last address
				 * specified in the option, as that is
				 * what the destination's IP header
				 * will look like.
				 */
				if (out)
					bcopy(ptr + off + ptr[off + 1] -
					    sizeof(struct in_addr),
					    &(ip->ip_dst), sizeof(struct in_addr));

				/* Fall through */
			default:
				/* Sanity check for option length. */
				if (ptr[off + 1] < 2) {
					DPRINTF(("ah_massage_headers(): "
					    "illegal IPv4 option length for "
					    "option %d\n", ptr[off]));
					ahstat.ahs_hdrops++;
					m_freem(m);
					return EINVAL;
				}

				/* Zeroize all other options. */
				count = ptr[off + 1];
				bcopy(ipseczeroes, ptr, count);
				off += count;
				break;
			}

			/* Sanity check. */
			if (off > skip)	{
				DPRINTF(("ah_massage_headers(): malformed "
				    "IPv4 options header\n"));

				ahstat.ahs_hdrops++;
				m_freem(m);
				return EINVAL;
			}
		}

		break;
#endif /* INET */

#ifdef INET6
	case AF_INET6:  /* Ugly... */
		/* Copy and "cook" the IPv6 header. */
		m_copydata(m, 0, sizeof(ip6), (caddr_t) &ip6);

		/* We don't do IPv6 Jumbograms. */
		if (ip6.ip6_plen == 0) {
			DPRINTF(("ah_massage_headers(): unsupported IPv6 "
			    "jumbogram"));
			ahstat.ahs_hdrops++;
			m_freem(m);
			return EMSGSIZE;
		}

		ip6.ip6_flow = 0;
		ip6.ip6_hlim = 0;
		ip6.ip6_vfc &= ~IPV6_VERSION_MASK;
		ip6.ip6_vfc |= IPV6_VERSION;

		/* Scoped address handling. */
		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;

		/* Done with IPv6 header. */
		m_copyback(m, 0, sizeof(struct ip6_hdr), &ip6);

		/* Let's deal with the remaining headers (if any). */
		if (skip - sizeof(struct ip6_hdr) > 0) {
			if (m->m_len <= skip) {
				MALLOC(ptr, unsigned char *,
				    skip - sizeof(struct ip6_hdr),
				    M_XDATA, M_NOWAIT);
				if (ptr == NULL) {
					DPRINTF(("ah_massage_headers(): failed to allocate memory for IPv6 headers\n"));
					ahstat.ahs_hdrops++;
					m_freem(m);
					return ENOBUFS;
				}

				/*
				 * Copy all the protocol headers after
				 * the IPv6 header.
				 */
				m_copydata(m, sizeof(struct ip6_hdr),
				    skip - sizeof(struct ip6_hdr), ptr);
				alloc = 1;
			} else {
				/* No need to allocate memory. */
				ptr = mtod(m, unsigned char *) +
				    sizeof(struct ip6_hdr);
				alloc = 0;
			}
		} else
			break;

		off = ip6.ip6_nxt & 0xff; /* Next header type. */

		for (len = 0; len < skip - sizeof(struct ip6_hdr);)
			switch (off) {
			case IPPROTO_HOPOPTS:
			case IPPROTO_DSTOPTS:
				ip6e = (struct ip6_ext *) (ptr + len);

				/*
				 * Process the mutable/immutable
				 * options -- borrows heavily from the
				 * KAME code.
				 */
				for (count = len + sizeof(struct ip6_ext);
				     count < len + ((ip6e->ip6e_len + 1) << 3);) {
					if (ptr[count] == IP6OPT_PAD1) {
						count++;
						continue; /* Skip padding. */
					}

					/* Sanity check. */
					if (count > len +
					    ((ip6e->ip6e_len + 1) << 3)) {
						ahstat.ahs_hdrops++;
						m_freem(m);

						/* Free, if we allocated. */
						if (alloc)
							FREE(ptr, M_XDATA);
						return EINVAL;
					}

					ad = ptr[count + 1];

					/* If mutable option, zeroize. */
					if (ptr[count] & IP6OPT_MUTABLE)
						bcopy(ipseczeroes, ptr + count,
						    ptr[count + 1]);

					count += ad;

					/* Sanity check. */
					if (count >
					    skip - sizeof(struct ip6_hdr)) {
						ahstat.ahs_hdrops++;
						m_freem(m);

						/* Free, if we allocated. */
						if (alloc)
							FREE(ptr, M_XDATA);
						return EINVAL;
					}
				}

				/* Advance. */
				len += ((ip6e->ip6e_len + 1) << 3);
				off = ip6e->ip6e_nxt;
				break;

			case IPPROTO_ROUTING:
				/*
				 * Always include routing headers in
				 * computation.
				 */
				ip6e = (struct ip6_ext *) (ptr + len);
				len += ((ip6e->ip6e_len + 1) << 3);
				off = ip6e->ip6e_nxt;
				break;

			default:
				DPRINTF(("ah_massage_headers(): unexpected "
				    "IPv6 header type %d\n", off));
				if (alloc)
					FREE(ptr, M_XDATA);
				ahstat.ahs_hdrops++;
				m_freem(m);
				return EINVAL;
			}

		/* Copyback and free, if we allocated. */
		if (alloc) {
			m_copyback(m, sizeof(struct ip6_hdr),
			    skip - sizeof(struct ip6_hdr), ptr);
			FREE(ptr, M_XDATA);
		}

		break;
#endif /* INET6 */
	}

	return 0;
}

/*
 * ah_input() gets called to verify that an input packet
 * passes authentication.
 */
int
ah_input(struct mbuf *m, struct tdb *tdb, int skip, int protoff)
{
	struct auth_hash *ahx = (struct auth_hash *) tdb->tdb_authalgxform;
	struct tdb_ident *tdbi;
	struct tdb_crypto *tc;
	struct m_tag *mtag;
	u_int32_t btsx;
	u_int8_t hl;
	int rplen;

	struct cryptodesc *crda = NULL;
	struct cryptop *crp;

	if (!(tdb->tdb_flags & TDBF_NOREPLAY))
		rplen = AH_FLENGTH + sizeof(u_int32_t);
	else
		rplen = AH_FLENGTH;

	/* Save the AH header, we use it throughout. */
	m_copydata(m, skip + offsetof(struct ah, ah_hl), sizeof(u_int8_t),
	    (caddr_t) &hl);

	/* Replay window checking, if applicable. */
	if ((tdb->tdb_wnd > 0) && (!(tdb->tdb_flags & TDBF_NOREPLAY))) {
		m_copydata(m, skip + offsetof(struct ah, ah_rpl),
		    sizeof(u_int32_t), (caddr_t) &btsx);
		btsx = ntohl(btsx);

		switch (checkreplaywindow32(btsx, 0, &(tdb->tdb_rpl),
		    tdb->tdb_wnd, &(tdb->tdb_bitmap), 0)) {
		case 0: /* All's well. */
			break;

		case 1:
			DPRINTF(("ah_input(): replay counter wrapped for "
			    "SA %s/%08x\n", ipsp_address(tdb->tdb_dst),
			    ntohl(tdb->tdb_spi)));

			ahstat.ahs_wrap++;
			m_freem(m);
			return ENOBUFS;

		case 2:
		case 3:
			DPRINTF(("ah_input(): duplicate packet received in "
			    "SA %s/%08x\n", ipsp_address(tdb->tdb_dst),
			    ntohl(tdb->tdb_spi)));

			m_freem(m);
			return ENOBUFS;

		default:
			DPRINTF(("ah_input(): bogus value from "
			    "checkreplaywindow32() in SA %s/%08x\n",
			    ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi)));

			ahstat.ahs_replay++;
			m_freem(m);
			return ENOBUFS;
		}
	}

	/* Verify AH header length. */
	if (hl * sizeof(u_int32_t) != ahx->authsize + rplen - AH_FLENGTH) {
		DPRINTF(("ah_input(): bad authenticator length %d for packet "
		    "in SA %s/%08x\n", hl * sizeof(u_int32_t),
		    ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi)));

		ahstat.ahs_badauthl++;
		m_freem(m);
		return EACCES;
	}

	/* Update the counters. */
	tdb->tdb_cur_bytes +=
	    (m->m_pkthdr.len - skip - hl * sizeof(u_int32_t));
	ahstat.ahs_ibytes += (m->m_pkthdr.len - skip - hl * sizeof(u_int32_t));

	/* Hard expiration. */
	if (tdb->tdb_flags & TDBF_BYTES &&
	    tdb->tdb_cur_bytes >= tdb->tdb_exp_bytes) {
		pfkeyv2_expire(tdb, SADB_EXT_LIFETIME_HARD);
		tdb_delete(tdb);
		m_freem(m);
		return ENXIO;
	}

	/* Notify on expiration. */
	if (tdb->tdb_flags & TDBF_SOFT_BYTES &&
	    tdb->tdb_cur_bytes >= tdb->tdb_soft_bytes) {
		pfkeyv2_expire(tdb, SADB_EXT_LIFETIME_SOFT);
		tdb->tdb_flags &= ~TDBF_SOFT_BYTES;  /* Turn off checking. */
	}

	/* Get crypto descriptors. */
	crp = crypto_getreq(1);
	if (crp == NULL) {
		m_freem(m);
		DPRINTF(("ah_input(): failed to acquire crypto "
		    "descriptors\n"));
		ahstat.ahs_crypto++;
		return ENOBUFS;
	}

	crda = crp->crp_desc;

	crda->crd_skip = 0;
	crda->crd_len = m->m_pkthdr.len;
	crda->crd_inject = skip + rplen;

	/* Authentication operation. */
	crda->crd_alg = ahx->type;
	crda->crd_key = tdb->tdb_amxkey;
	crda->crd_klen = tdb->tdb_amxkeylen * 8;

	/* Find out if we've already done crypto. */
	for (mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, NULL);
	     mtag != NULL;
	     mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, mtag)) {
		tdbi = (struct tdb_ident *) (mtag + 1);
		if (tdbi->proto == tdb->tdb_sproto &&
		    tdbi->spi == tdb->tdb_spi &&
		    !bcmp(&tdbi->dst, &tdb->tdb_dst,
			sizeof(union sockaddr_union)))
			break;
	}

	/* Allocate IPsec-specific opaque crypto info. */
	if (mtag == NULL)
		MALLOC(tc, struct tdb_crypto *,
		    sizeof(struct tdb_crypto) + skip +
		    rplen + ahx->authsize, M_XDATA, M_NOWAIT);
	else /* Hash verification has already been done successfully. */
		MALLOC(tc, struct tdb_crypto *, sizeof(struct tdb_crypto),
		    M_XDATA, M_NOWAIT);
	if (tc == NULL) {
		m_freem(m);
		crypto_freereq(crp);
		DPRINTF(("ah_input(): failed to allocate tdb_crypto\n"));
		ahstat.ahs_crypto++;
		return ENOBUFS;
	}

	bzero(tc, sizeof(struct tdb_crypto));

	/* Only save information if crypto processing is needed. */
	if (mtag == NULL) {
		/*
		 * Save the authenticator, the skipped portion of the packet,
		 * and the AH header.
		 */
		m_copydata(m, 0, skip + rplen + ahx->authsize,
		    (caddr_t) (tc + 1));

		/* Zeroize the authenticator on the packet. */
		m_copyback(m, skip + rplen, ahx->authsize, ipseczeroes);

		/* "Massage" the packet headers for crypto processing. */
		if ((btsx = ah_massage_headers(&m, tdb->tdb_dst.sa.sa_family,
		    skip, ahx->type, 0)) != 0) {
			/* mbuf will be free'd by callee. */
			FREE(tc, M_XDATA);
			crypto_freereq(crp);
			return btsx;
		}
	}

	/* Crypto operation descriptor. */
	crp->crp_ilen = m->m_pkthdr.len; /* Total input length. */
	crp->crp_flags = CRYPTO_F_IMBUF;
	crp->crp_buf = (caddr_t) m;
	crp->crp_callback = (int (*) (struct cryptop *)) ah_input_cb;
	crp->crp_sid = tdb->tdb_cryptoid;
	crp->crp_opaque = (caddr_t) tc;

	/* These are passed as-is to the callback. */
	tc->tc_skip = skip;
	tc->tc_protoff = protoff;
	tc->tc_spi = tdb->tdb_spi;
	tc->tc_proto = tdb->tdb_sproto;
	tc->tc_ptr = (caddr_t) mtag; /* Save the mtag we've identified. */
	bcopy(&tdb->tdb_dst, &tc->tc_dst, sizeof(union sockaddr_union));

	if (mtag == NULL)
		return crypto_dispatch(crp);
	else
		return ah_input_cb(crp);
}

/*
 * AH input callback, called directly by the crypto driver.
 */
int
ah_input_cb(void *op)
{
	int s, roff, rplen, error, skip, protoff;
	unsigned char calc[AH_ALEN_MAX];
	struct mbuf *m1, *m0, *m;
	struct cryptodesc *crd;
	struct auth_hash *ahx;
	struct tdb_crypto *tc;
	struct cryptop *crp;
	struct m_tag *mtag;
	struct tdb *tdb;
	u_int32_t btsx;
	u_int8_t prot;
	caddr_t ptr;

	crp = (struct cryptop *) op;
	crd = crp->crp_desc;

	tc = (struct tdb_crypto *) crp->crp_opaque;
	skip = tc->tc_skip;
	protoff = tc->tc_protoff;
	mtag = (struct m_tag *) tc->tc_ptr;

	m = (struct mbuf *) crp->crp_buf;
	if (m == NULL) {
		/* Shouldn't happen... */
		FREE(tc, M_XDATA);
		crypto_freereq(crp);
		ahstat.ahs_crypto++;
		DPRINTF(("ah_input_cb(): bogus returned buffer from "
		    "crypto\n"));
		return (EINVAL);
	}

	s = spltdb();

	tdb = gettdb(tc->tc_spi, &tc->tc_dst, tc->tc_proto);
	if (tdb == NULL) {
		FREE(tc, M_XDATA);
		ahstat.ahs_notdb++;
		DPRINTF(("ah_input_cb(): TDB is expired while in crypto"));
		error = EPERM;
		goto baddone;
	}

	ahx = (struct auth_hash *) tdb->tdb_authalgxform;

	/* Check for crypto errors. */
	if (crp->crp_etype) {
		if (crp->crp_etype == EAGAIN) {
			/* Reset the session ID */
			if (tdb->tdb_cryptoid != 0)
				tdb->tdb_cryptoid = crp->crp_sid;
			splx(s);
			return crypto_dispatch(crp);
		}
		FREE(tc, M_XDATA);
		ahstat.ahs_noxform++;
		DPRINTF(("ah_input_cb(): crypto error %d\n", crp->crp_etype));
		error = crp->crp_etype;
		goto baddone;
	} else {
		crypto_freereq(crp); /* No longer needed. */
		crp = NULL;
	}

	if (!(tdb->tdb_flags & TDBF_NOREPLAY))
		rplen = AH_FLENGTH + sizeof(u_int32_t);
	else
		rplen = AH_FLENGTH;

	/* Copy authenticator off the packet. */
	m_copydata(m, skip + rplen, ahx->authsize, calc);

	/*
	 * If we have an mtag, we don't need to verify the authenticator --
	 * it has been verified by an IPsec-aware NIC.
	 */
	if (mtag == NULL) {
		ptr = (caddr_t) (tc + 1);

		/* Verify authenticator. */
		if (bcmp(ptr + skip + rplen, calc, ahx->authsize)) {
			FREE(tc, M_XDATA);

			DPRINTF(("ah_input(): authentication failed for "
			    "packet in SA %s/%08x\n",
			    ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi)));

			ahstat.ahs_badauth++;
			error = EACCES;
			goto baddone;
		}

		/* Fix the Next Protocol field. */
		((u_int8_t *) ptr)[protoff] = ((u_int8_t *) ptr)[skip];

		/* Copyback the saved (uncooked) network headers. */
		m_copyback(m, 0, skip, ptr);
	} else {
		/* Fix the Next Protocol field. */
		m_copydata(m, skip, sizeof(u_int8_t), &prot);
		m_copyback(m, protoff, sizeof(u_int8_t), &prot);
	}

	FREE(tc, M_XDATA);

	/* Replay window checking, if applicable. */
	if ((tdb->tdb_wnd > 0) && (!(tdb->tdb_flags & TDBF_NOREPLAY))) {
		m_copydata(m, skip + offsetof(struct ah, ah_rpl),
		    sizeof(u_int32_t), (caddr_t) &btsx);
		btsx = ntohl(btsx);

		switch (checkreplaywindow32(btsx, 0, &(tdb->tdb_rpl),
		    tdb->tdb_wnd, &(tdb->tdb_bitmap), 1)) {
		case 0: /* All's well. */
			break;

		case 1:
			DPRINTF(("ah_input(): replay counter wrapped for "
			    "SA %s/%08x\n", ipsp_address(tdb->tdb_dst),
			    ntohl(tdb->tdb_spi)));

			ahstat.ahs_wrap++;
			error = ENOBUFS;
			goto baddone;

		case 2:
		case 3:
			DPRINTF(("ah_input_cb(): duplicate packet received in "
			    "SA %s/%08x\n", ipsp_address(tdb->tdb_dst),
			    ntohl(tdb->tdb_spi)));

			error = ENOBUFS;
			goto baddone;

		default:
			DPRINTF(("ah_input_cb(): bogus value from "
			    "checkreplaywindow32() in SA %s/%08x\n",
			    ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi)));

			ahstat.ahs_replay++;
			error = ENOBUFS;
			goto baddone;
		}
	}

	/* Record the beginning of the AH header. */
	m1 = m_getptr(m, skip, &roff);
	if (m1 == NULL) {
		ahstat.ahs_hdrops++;
		splx(s);
		m_freem(m);

		DPRINTF(("ah_input(): bad mbuf chain for packet in SA "
		    "%s/%08x\n", ipsp_address(tdb->tdb_dst),
		    ntohl(tdb->tdb_spi)));

		return EINVAL;
	}

	/* Remove the AH header from the mbuf. */
	if (roff == 0) {
		/*
		 * The AH header was conveniently at the beginning of
		 * the mbuf.
		 */
		m_adj(m1, rplen + ahx->authsize);
		if (!(m1->m_flags & M_PKTHDR))
			m->m_pkthdr.len -= rplen + ahx->authsize;
	} else
		if (roff + rplen + ahx->authsize >= m1->m_len) {
			/*
			 * Part or all of the AH header is at the end
			 * of this mbuf, so first let's remove the
			 * remainder of the AH header from the
			 * beginning of the remainder of the mbuf
			 * chain, if any.
			 */
			if (roff + rplen + ahx->authsize > m1->m_len) {
				/* Adjust the next mbuf by the remainder. */
				m_adj(m1->m_next, roff + rplen +
				    ahx->authsize - m1->m_len);

				/*
				 * The second mbuf is guaranteed not
				 * to have a pkthdr...
				 */
				m->m_pkthdr.len -=
				    (roff + rplen + ahx->authsize - m1->m_len);
			}

			/* Now, let's unlink the mbuf chain for a second... */
			m0 = m1->m_next;
			m1->m_next = NULL;

			/*
			 * ...and trim the end of the first part of
			 * the chain...sick
			 */
			m_adj(m1, -(m1->m_len - roff));
			if (!(m1->m_flags & M_PKTHDR))
				m->m_pkthdr.len -= (m1->m_len - roff);

			/* Finally, let's relink. */
			m1->m_next = m0;
		} else {
			/*
			 * The AH header lies in the "middle" of the
			 * mbuf...do an overlapping copy of the
			 * remainder of the mbuf over the ESP header.
			 */
			bcopy(mtod(m1, u_char *) + roff + rplen +
			    ahx->authsize, mtod(m1, u_char *) + roff,
			    m1->m_len - (roff + rplen + ahx->authsize));
			m1->m_len -= rplen + ahx->authsize;
			m->m_pkthdr.len -= rplen + ahx->authsize;
		}

	error = ipsec_common_input_cb(m, tdb, skip, protoff, mtag);
	splx(s);
	return (error);

 baddone:
	splx(s);

	if (m != NULL)
		m_freem(m);

	if (crp != NULL)
		crypto_freereq(crp);

	return (error);
}

/*
 * AH output routine, called by ipsp_process_packet().
 */
int
ah_output(struct mbuf *m, struct tdb *tdb, struct mbuf **mp, int skip,
    int protoff)
{
	struct auth_hash *ahx = (struct auth_hash *) tdb->tdb_authalgxform;
	struct cryptodesc *crda;
	struct tdb_crypto *tc;
	struct mbuf *mo, *mi;
	struct cryptop *crp;
	u_int16_t iplen;
	int len, rplen;
	u_int8_t prot;
	struct ah *ah;

#if NBPFILTER > 0
	{
		struct ifnet *ifn;
		struct enchdr hdr;
		struct mbuf m1;

		bzero (&hdr, sizeof(hdr));

		hdr.af = tdb->tdb_dst.sa.sa_family;
		hdr.spi = tdb->tdb_spi;
		hdr.flags |= M_AUTH | M_AUTH_AH;

		m1.m_flags = 0;
		m1.m_next = m;
		m1.m_len = ENC_HDRLEN;
		m1.m_data = (char *) &hdr;

		ifn = &(encif[0].sc_if);

		if (ifn->if_bpf)
			bpf_mtap(ifn->if_bpf, &m1);
	}
#endif

	ahstat.ahs_output++;

	/*
	 * Check for replay counter wrap-around in automatic (not
	 * manual) keying.
	 */
	if ((tdb->tdb_rpl == 0) && (tdb->tdb_wnd > 0) &&
	    (!(tdb->tdb_flags & TDBF_NOREPLAY))) {
		DPRINTF(("ah_output(): SA %s/%08x should have expired\n",
		    ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi)));
		m_freem(m);
		ahstat.ahs_wrap++;
		return EINVAL;
	}

	if (!(tdb->tdb_flags & TDBF_NOREPLAY))
		rplen = AH_FLENGTH + sizeof(u_int32_t);
	else
		rplen = AH_FLENGTH;

	switch (tdb->tdb_dst.sa.sa_family) {
#ifdef INET
	case AF_INET:
		/* Check for IP maximum packet size violations. */
		if (rplen + ahx->authsize + m->m_pkthdr.len > IP_MAXPACKET) {
			DPRINTF(("ah_output(): packet in SA %s/%08x got too "
			    "big\n",
			    ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi)));
			m_freem(m);
			ahstat.ahs_toobig++;
			return EMSGSIZE;
		}
		break;
#endif /* INET */

#ifdef INET6
	case AF_INET6:
		/* Check for IPv6 maximum packet size violations. */
		if (rplen + ahx->authsize + m->m_pkthdr.len > IPV6_MAXPACKET) {
			DPRINTF(("ah_output(): packet in SA %s/%08x "
			    "got too big\n", ipsp_address(tdb->tdb_dst),
			    ntohl(tdb->tdb_spi)));
			m_freem(m);
			ahstat.ahs_toobig++;
			return EMSGSIZE;
		}
		break;
#endif /* INET6 */

	default:
		DPRINTF(("ah_output(): unknown/unsupported protocol "
		    "family %d, SA %s/%08x\n", tdb->tdb_dst.sa.sa_family,
		    ipsp_address(tdb->tdb_dst), ntohl(tdb->tdb_spi)));
		m_freem(m);
		ahstat.ahs_nopf++;
		return EPFNOSUPPORT;
	}

	/* Update the counters. */
	tdb->tdb_cur_bytes += m->m_pkthdr.len - skip;
	ahstat.ahs_obytes += m->m_pkthdr.len - skip;

	/* Hard expiration. */
	if (tdb->tdb_flags & TDBF_BYTES &&
	    tdb->tdb_cur_bytes >= tdb->tdb_exp_bytes) {
		pfkeyv2_expire(tdb, SADB_EXT_LIFETIME_HARD);
		tdb_delete(tdb);
		m_freem(m);
		return EINVAL;
	}

	/* Notify on expiration. */
	if (tdb->tdb_flags & TDBF_SOFT_BYTES &&
	    tdb->tdb_cur_bytes >= tdb->tdb_soft_bytes) {
		pfkeyv2_expire(tdb, SADB_EXT_LIFETIME_SOFT);
		tdb->tdb_flags &= ~TDBF_SOFT_BYTES; /* Turn off checking */
	}

	/*
	 * Loop through mbuf chain; if we find an M_EXT mbuf with
	 * more than one reference, replace the rest of the chain.
	 */
	mo = NULL;
	mi = m;
	while (mi != NULL &&
	    (!(mi->m_flags & M_EXT) || !MCLISREFERENCED(mi))) {
		mo = mi;
		mi = mi->m_next;
	}

	if (mi != NULL) {
		/* Replace the rest of the mbuf chain. */
		struct mbuf *n = m_copym2(mi, 0, M_COPYALL, M_DONTWAIT);

		if (n == NULL) {
			ahstat.ahs_hdrops++;
			m_freem(m);
			return ENOBUFS;
		}

		if (mo != NULL)
			mo->m_next = n;
		else
			m = n;

		m_freem(mi);
	}

	/* Inject AH header. */
	mi = m_inject(m, skip, rplen + ahx->authsize, M_DONTWAIT);
	if (mi == NULL) {
		DPRINTF(("ah_output(): failed to inject AH header for SA "
		    "%s/%08x\n", ipsp_address(tdb->tdb_dst),
		    ntohl(tdb->tdb_spi)));

		m_freem(m);
		ahstat.ahs_hdrops++;
		return ENOBUFS;
	}

	/*
	 * The AH header is guaranteed by m_inject() to be in
	 * contiguous memory, at the beginning of the returned mbuf.
	 */
	ah = mtod(mi, struct ah *);

	/* Initialize the AH header. */
	m_copydata(m, protoff, sizeof(u_int8_t), (caddr_t) &ah->ah_nh);
	ah->ah_hl = (rplen + ahx->authsize - AH_FLENGTH) / sizeof(u_int32_t);
	ah->ah_rv = 0;
	ah->ah_spi = tdb->tdb_spi;

	/* Zeroize authenticator. */
	m_copyback(m, skip + rplen, ahx->authsize, ipseczeroes);

	if (!(tdb->tdb_flags & TDBF_NOREPLAY))
		ah->ah_rpl = htonl(tdb->tdb_rpl++);

	/* Get crypto descriptors. */
	crp = crypto_getreq(1);
	if (crp == NULL) {
		m_freem(m);
		DPRINTF(("ah_output(): failed to acquire crypto "
		    "descriptors\n"));
		ahstat.ahs_crypto++;
		return ENOBUFS;
	}

	crda = crp->crp_desc;

	crda->crd_skip = 0;
	crda->crd_inject = skip + rplen;
	crda->crd_len = m->m_pkthdr.len;

	/* Authentication operation. */
	crda->crd_alg = ahx->type;
	crda->crd_key = tdb->tdb_amxkey;
	crda->crd_klen = tdb->tdb_amxkeylen * 8;

	/* Allocate IPsec-specific opaque crypto info. */
	if ((tdb->tdb_flags & TDBF_SKIPCRYPTO) == 0)
		MALLOC(tc, struct tdb_crypto *,
		    sizeof(struct tdb_crypto) + skip, M_XDATA, M_NOWAIT);
	else
		MALLOC(tc, struct tdb_crypto *,
		    sizeof(struct tdb_crypto), M_XDATA, M_NOWAIT);
	if (tc == NULL) {
		m_freem(m);
		crypto_freereq(crp);
		DPRINTF(("ah_output(): failed to allocate tdb_crypto\n"));
		ahstat.ahs_crypto++;
		return ENOBUFS;
	}

	bzero(tc, sizeof(struct tdb_crypto));

	/* Save the skipped portion of the packet. */
	if ((tdb->tdb_flags & TDBF_SKIPCRYPTO) == 0) {
		m_copydata(m, 0, skip, (caddr_t) (tc + 1));

		/*
		 * Fix IP header length on the header used for
		 * authentication. We don't need to fix the original
		 * header length as it will be fixed by our caller.
		 */
		switch (tdb->tdb_dst.sa.sa_family) {
#ifdef INET
		case AF_INET:
			bcopy(((caddr_t)(tc + 1)) +
			    offsetof(struct ip, ip_len),
			    (caddr_t) &iplen, sizeof(u_int16_t));
			iplen = htons(ntohs(iplen) + rplen + ahx->authsize);
			m_copyback(m, offsetof(struct ip, ip_len),
			    sizeof(u_int16_t), &iplen);
			break;
#endif /* INET */

#ifdef INET6
		case AF_INET6:
			bcopy(((caddr_t)(tc + 1)) +
			    offsetof(struct ip6_hdr, ip6_plen),
			    (caddr_t) &iplen, sizeof(u_int16_t));
			iplen = htons(ntohs(iplen) + rplen + ahx->authsize);
			m_copyback(m, offsetof(struct ip6_hdr, ip6_plen),
			    sizeof(u_int16_t), &iplen);
			break;
#endif /* INET6 */
		}

		/* Fix the Next Header field in saved header. */
		((u_int8_t *) (tc + 1))[protoff] = IPPROTO_AH;

		/* Update the Next Protocol field in the IP header. */
		prot = IPPROTO_AH;
		m_copyback(m, protoff, sizeof(u_int8_t), &prot);

		/* "Massage" the packet headers for crypto processing. */
		if ((len = ah_massage_headers(&m, tdb->tdb_dst.sa.sa_family,
		    skip, ahx->type, 1)) != 0) {
			/* mbuf will be free'd by callee. */
			FREE(tc, M_XDATA);
			crypto_freereq(crp);
			return len;
		}
	} else {
		/* Update the Next Protocol field in the IP header. */
		prot = IPPROTO_AH;
		m_copyback(m, protoff, sizeof(u_int8_t), &prot);
	}

	/* Crypto operation descriptor. */
	crp->crp_ilen = m->m_pkthdr.len; /* Total input length. */
	crp->crp_flags = CRYPTO_F_IMBUF;
	crp->crp_buf = (caddr_t) m;
	crp->crp_callback = (int (*) (struct cryptop *)) ah_output_cb;
	crp->crp_sid = tdb->tdb_cryptoid;
	crp->crp_opaque = (caddr_t) tc;

	/* These are passed as-is to the callback. */
	tc->tc_skip = skip;
	tc->tc_protoff = protoff;
	tc->tc_spi = tdb->tdb_spi;
	tc->tc_proto = tdb->tdb_sproto;
	bcopy(&tdb->tdb_dst, &tc->tc_dst, sizeof(union sockaddr_union));

	if ((tdb->tdb_flags & TDBF_SKIPCRYPTO) == 0)
		return crypto_dispatch(crp);
	else
		return ah_output_cb(crp);
}

/*
 * AH output callback, called directly from the crypto handler.
 */
int
ah_output_cb(void *op)
{
	int skip, protoff, error;
	struct tdb_crypto *tc;
	struct cryptop *crp;
	struct tdb *tdb;
	struct mbuf *m;
	caddr_t ptr;
	int err, s;

	crp = (struct cryptop *) op;
	tc = (struct tdb_crypto *) crp->crp_opaque;
	skip = tc->tc_skip;
	protoff = tc->tc_protoff;
	ptr = (caddr_t) (tc + 1);

	m = (struct mbuf *) crp->crp_buf;
	if (m == NULL) {
		/* Shouldn't happen... */
		FREE(tc, M_XDATA);
		crypto_freereq(crp);
		ahstat.ahs_crypto++;
		DPRINTF(("ah_output_cb(): bogus returned buffer from "
		    "crypto\n"));
		return (EINVAL);
	}

	s = spltdb();

	tdb = gettdb(tc->tc_spi, &tc->tc_dst, tc->tc_proto);
	if (tdb == NULL) {
		FREE(tc, M_XDATA);
		ahstat.ahs_notdb++;
		DPRINTF(("ah_output_cb(): TDB is expired while in crypto\n"));
		error = EPERM;
		goto baddone;
	}

	/* Check for crypto errors. */
	if (crp->crp_etype) {
		if (crp->crp_etype == EAGAIN) {
			/* Reset the session ID */
			if (tdb->tdb_cryptoid != 0)
				tdb->tdb_cryptoid = crp->crp_sid;
			splx(s);
			return crypto_dispatch(crp);
		}
		FREE(tc, M_XDATA);
		ahstat.ahs_noxform++;
		DPRINTF(("ah_output_cb(): crypto error %d\n", crp->crp_etype));
		error = crp->crp_etype;
		goto baddone;
	}

	/*
	 * Copy original headers (with the new protocol number) back
	 * in place.
	 */
	if ((tdb->tdb_flags & TDBF_SKIPCRYPTO) == 0)
		m_copyback(m, 0, skip, ptr);

	FREE(tc, M_XDATA);

	/* No longer needed. */
	crypto_freereq(crp);

	err =  ipsp_process_done(m, tdb);
	splx(s);
	return err;

 baddone:
	splx(s);

	if (m != NULL)
		m_freem(m);

	crypto_freereq(crp);

	return error;
}
