/*      $OpenBSD: ip_ah.c,v 1.63 2001/06/26 06:18:58 angelos 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 "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/socket.h>
#include <sys/syslog.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sysctl.h>

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

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_ecn.h>
#include <netinet/ip6.h>

#include <netipsec/ipsec.h>
#include <netipsec/ah.h>
#include <netipsec/ah_var.h>
#include <netipsec/xform.h>

#ifdef INET6
#include <netinet6/ip6_var.h>
#include <netipsec/ipsec6.h>
#include <netinet6/ip6_ecn.h>
#endif

#include <netipsec/key.h>
#include <netipsec/key_debug.h>

#include <opencrypto/cryptodev.h>

/*
 * Return header size in bytes.  The old protocol did not support
 * the replay counter; the new protocol always includes the counter.
 */
#define HDRSIZE(sav) \
        (((sav)->flags & SADB_X_EXT_OLD) ? \
                sizeof (struct ah) : sizeof (struct ah) + sizeof (u_int32_t))
/* 
 * Return authenticator size in bytes, based on a field in the
 * algorithm descriptor.
 */
#define AUTHSIZE(sav)   ((sav->flags & SADB_X_EXT_OLD) ? 16 :   \
                         xform_ah_authsize((sav)->tdb_authalgxform))

VNET_DEFINE(int, ah_enable) = 1;        /* control flow of packets with AH */
VNET_DEFINE(int, ah_cleartos) = 1;      /* clear ip_tos when doing AH calc */
VNET_PCPUSTAT_DEFINE(struct ahstat, ahstat);
VNET_PCPUSTAT_SYSINIT(ahstat);

#ifdef VIMAGE
VNET_PCPUSTAT_SYSUNINIT(ahstat);
#endif /* VIMAGE */

#ifdef INET
SYSCTL_DECL(_net_inet_ah);
SYSCTL_INT(_net_inet_ah, OID_AUTO, ah_enable,
        CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ah_enable), 0, "");
SYSCTL_INT(_net_inet_ah, OID_AUTO, ah_cleartos,
        CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ah_cleartos), 0, "");
SYSCTL_VNET_PCPUSTAT(_net_inet_ah, IPSECCTL_STATS, stats, struct ahstat,
    ahstat, "AH statistics (struct ahstat, netipsec/ah_var.h)");
#endif

static MALLOC_DEFINE(M_AH, "ah", "IPsec AH");

static unsigned char ipseczeroes[256];  /* larger than an ip6 extension hdr */

static int ah_input_cb(struct cryptop*);
static int ah_output_cb(struct cryptop*);

int
xform_ah_authsize(const struct auth_hash *esph)
{
        int alen;

        if (esph == NULL)
                return 0;

        switch (esph->type) {
        case CRYPTO_SHA2_256_HMAC:
        case CRYPTO_SHA2_384_HMAC:
        case CRYPTO_SHA2_512_HMAC:
                alen = esph->hashsize / 2;      /* RFC4868 2.3 */
                break;

        case CRYPTO_POLY1305:
        case CRYPTO_AES_NIST_GMAC:
                alen = esph->hashsize;
                break;

        default:
                alen = AH_HMAC_HASHLEN;
                break;
        }

        return alen;
}

size_t
ah_hdrsiz(struct secasvar *sav)
{
        size_t size;

        if (sav != NULL) {
                int authsize, rplen, align;

                IPSEC_ASSERT(sav->tdb_authalgxform != NULL, ("null xform"));
                /*XXX not right for null algorithm--does it matter??*/

                /* RFC4302: use the correct alignment. */
                align = sizeof(uint32_t);
#ifdef INET6
                if (sav->sah->saidx.dst.sa.sa_family == AF_INET6) {
                        align = sizeof(uint64_t);
                }
#endif
                rplen = HDRSIZE(sav);
                authsize = AUTHSIZE(sav);
                size = roundup(rplen + authsize, align);
        } else {
                /* default guess */
                size = sizeof (struct ah) + sizeof (u_int32_t) + 16;
        }
        return size;
}

/*
 * NB: public for use by esp_init.
 */
int
ah_init0(struct secasvar *sav, struct xformsw *xsp,
    struct crypto_session_params *csp)
{
        const struct auth_hash *thash;
        int keylen;

        thash = auth_algorithm_lookup(sav->alg_auth);
        if (thash == NULL) {
                DPRINTF(("%s: unsupported authentication algorithm %u\n",
                        __func__, sav->alg_auth));
                return EINVAL;
        }

        /*
         * Verify the replay state block allocation is consistent with
         * the protocol type.  We check here so we can make assumptions
         * later during protocol processing.
         */
        /* NB: replay state is setup elsewhere (sigh) */
        if (((sav->flags&SADB_X_EXT_OLD) == 0) ^ (sav->replay != NULL)) {
                DPRINTF(("%s: replay state block inconsistency, "
                        "%s algorithm %s replay state\n", __func__,
                        (sav->flags & SADB_X_EXT_OLD) ? "old" : "new",
                        sav->replay == NULL ? "without" : "with"));
                return EINVAL;
        }
        if (sav->key_auth == NULL) {
                DPRINTF(("%s: no authentication key for %s algorithm\n",
                        __func__, thash->name));
                return EINVAL;
        }
        keylen = _KEYLEN(sav->key_auth);
        if (keylen > thash->keysize && thash->keysize != 0) {
                DPRINTF(("%s: invalid keylength %d, algorithm %s requires "
                        "keysize less than %d\n", __func__,
                         keylen, thash->name, thash->keysize));
                return EINVAL;
        }

        sav->tdb_xform = xsp;
        sav->tdb_authalgxform = thash;

        /* Initialize crypto session. */
        csp->csp_auth_alg = sav->tdb_authalgxform->type;
        if (csp->csp_auth_alg != CRYPTO_NULL_HMAC) {
                csp->csp_auth_klen = _KEYBITS(sav->key_auth) / 8;
                csp->csp_auth_key = sav->key_auth->key_data;
        };
        csp->csp_auth_mlen = AUTHSIZE(sav);

        return 0;
}

/*
 * ah_init() is called when an SPI is being set up.
 */
static int
ah_init(struct secasvar *sav, struct xformsw *xsp)
{
        struct crypto_session_params csp;
        int error;

        memset(&csp, 0, sizeof(csp));
        csp.csp_mode = CSP_MODE_DIGEST;

        if (sav->flags & SADB_X_SAFLAGS_ESN)
                csp.csp_flags |= CSP_F_ESN;

        error = ah_init0(sav, xsp, &csp);
        return error ? error :
                 crypto_newsession(&sav->tdb_cryptoid, &csp, V_crypto_support);
}

static void
ah_cleanup(struct secasvar *sav)
{

        crypto_freesession(sav->tdb_cryptoid);
        sav->tdb_cryptoid = NULL;
        sav->tdb_authalgxform = NULL;
}

/*
 * Massage IPv4/IPv6 headers for AH processing.
 */
static 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 ad, alloc, nxt, noff;
#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(("%s: m_pullup failed\n", __func__));
                        return ENOBUFS;
                }

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

                ptr = mtod(m, unsigned char *);

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

                                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(("%s: illegal IPv4 option "
                                                "length for option %d\n",
                                                __func__, ptr[off]));

                                        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(("%s: illegal IPv4 option "
                                                "length for option %d\n",
                                                __func__, ptr[off]));

                                        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(("%s: illegal IPv4 option "
                                                "length for option %d\n",
                                                __func__, ptr[off]));
                                        m_freem(m);
                                        return EINVAL;
                                }

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

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

                                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(("%s: unsupported IPv6 jumbogram\n", __func__));
                        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), (caddr_t) &ip6);

                /* Let's deal with the remaining headers (if any). */
                if (skip - sizeof(struct ip6_hdr) > 0) {
                        if (m->m_len <= skip) {
                                ptr = (unsigned char *) malloc(
                                    skip - sizeof(struct ip6_hdr),
                                    M_AH, M_NOWAIT);
                                if (ptr == NULL) {
                                        DPRINTF(("%s: failed to allocate memory"
                                                "for IPv6 headers\n",__func__));
                                        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;

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

                for (off = 0; off < skip - sizeof(struct ip6_hdr);)
                        switch (nxt) {
                        case IPPROTO_HOPOPTS:
                        case IPPROTO_DSTOPTS:
                                ip6e = (struct ip6_ext *)(ptr + off);
                                noff = off + ((ip6e->ip6e_len + 1) << 3);

                                /* Sanity check. */
                                if (noff > skip - sizeof(struct ip6_hdr))
                                        goto error6;

                                /*
                                 * Zero out mutable options.
                                 */
                                for (count = off + sizeof(struct ip6_ext);
                                     count < noff;) {
                                        if (ptr[count] == IP6OPT_PAD1) {
                                                count++;
                                                continue; /* Skip padding. */
                                        }

                                        ad = ptr[count + 1] + 2;
                                        if (count + ad > noff)
                                                goto error6;

                                        if (ptr[count] & IP6OPT_MUTABLE)
                                                memset(ptr + count, 0, ad);
                                        count += ad;
                                }

                                if (count != noff)
                                        goto error6;

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

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

                        default:
                                DPRINTF(("%s: unexpected IPv6 header type %d",
                                        __func__, off));
error6:
                                if (alloc)
                                        free(ptr, M_AH);
                                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_AH);
                }

                break;
#endif /* INET6 */
        }

        return 0;
}

/*
 * ah_input() gets called to verify that an input packet
 * passes authentication.
 */
static int
ah_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
{
        IPSEC_DEBUG_DECLARE(char buf[128]);
        const struct auth_hash *ahx;
        struct cryptop *crp;
        struct xform_data *xd;
        struct newah *ah;
        crypto_session_t cryptoid;
        int hl, rplen, authsize, ahsize, error;
        uint32_t seqh;

        SECASVAR_RLOCK_TRACKER;

        IPSEC_ASSERT(sav != NULL, ("null SA"));
        IPSEC_ASSERT(sav->key_auth != NULL, ("null authentication key"));
        IPSEC_ASSERT(sav->tdb_authalgxform != NULL,
                ("null authentication xform"));

        /* Figure out header size. */
        rplen = HDRSIZE(sav);

        if (m->m_len < skip + rplen) {
                m = m_pullup(m, skip + rplen);
                if (m == NULL) {
                        DPRINTF(("ah_input: cannot pullup header\n"));
                        AHSTAT_INC(ahs_hdrops);         /*XXX*/
                        error = ENOBUFS;
                        goto bad;
                }
        }
        ah = (struct newah *)(mtod(m, caddr_t) + skip);

        /* Check replay window, if applicable. */
        SECASVAR_RLOCK(sav);
        if (sav->replay != NULL && sav->replay->wsize != 0 &&
            ipsec_chkreplay(ntohl(ah->ah_seq), &seqh, sav) == 0) {
                SECASVAR_RUNLOCK(sav);
                AHSTAT_INC(ahs_replay);
                DPRINTF(("%s: packet replay failure: %s\n", __func__,
                    ipsec_sa2str(sav, buf, sizeof(buf))));
                error = EACCES;
                goto bad;
        }
        cryptoid = sav->tdb_cryptoid;
        SECASVAR_RUNLOCK(sav);

        /* Verify AH header length. */
        hl = sizeof(struct ah) + (ah->ah_len * sizeof (u_int32_t));
        ahx = sav->tdb_authalgxform;
        authsize = AUTHSIZE(sav);
        ahsize = ah_hdrsiz(sav);
        if (hl != ahsize) {
                DPRINTF(("%s: bad authenticator length %u (expecting %lu)"
                    " for packet in SA %s/%08lx\n", __func__, hl,
                    (u_long)ahsize,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi)));
                AHSTAT_INC(ahs_badauthl);
                error = EACCES;
                goto bad;
        }
        if (skip + ahsize > m->m_pkthdr.len) {
                DPRINTF(("%s: bad mbuf length %u (expecting %lu)"
                    " for packet in SA %s/%08lx\n", __func__,
                    m->m_pkthdr.len, (u_long)(skip + ahsize),
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi)));
                AHSTAT_INC(ahs_badauthl);
                error = EACCES;
                goto bad;
        }
        AHSTAT_ADD(ahs_ibytes, m->m_pkthdr.len - skip - hl);

        /* Get crypto descriptors. */
        crp = crypto_getreq(cryptoid, M_NOWAIT);
        if (crp == NULL) {
                DPRINTF(("%s: failed to acquire crypto descriptor\n",
                    __func__));
                AHSTAT_INC(ahs_crypto);
                error = ENOBUFS;
                goto bad;
        }

        crp->crp_payload_start = 0;
        crp->crp_payload_length = m->m_pkthdr.len;
        crp->crp_digest_start = skip + rplen;

        /* Allocate IPsec-specific opaque crypto info. */
        xd = malloc(sizeof(*xd) + skip + rplen + authsize, M_AH,
            M_NOWAIT | M_ZERO);
        if (xd == NULL) {
                DPRINTF(("%s: failed to allocate xform_data\n", __func__));
                AHSTAT_INC(ahs_crypto);
                crypto_freereq(crp);
                error = ENOBUFS;
                goto bad;
        }

        /*
         * Save the authenticator, the skipped portion of the packet,
         * and the AH header.
         */
        m_copydata(m, 0, skip + rplen + authsize, (caddr_t)(xd + 1));

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

        /* Save ah_nxt, since ah pointer can become invalid after "massage" */
        hl = ah->ah_nxt;

        /* "Massage" the packet headers for crypto processing. */
        error = ah_massage_headers(&m, sav->sah->saidx.dst.sa.sa_family,
            skip, ahx->type, 0);
        if (error != 0) {
                /* NB: mbuf is free'd by ah_massage_headers */
                AHSTAT_INC(ahs_hdrops);
                free(xd, M_AH);
                crypto_freereq(crp);
                key_freesav(&sav);
                return (error);
        }

        /* Crypto operation descriptor. */
        crp->crp_op = CRYPTO_OP_COMPUTE_DIGEST;
        crp->crp_flags = CRYPTO_F_CBIFSYNC;
        crypto_use_mbuf(crp, m);
        crp->crp_callback = ah_input_cb;
        crp->crp_opaque = xd;

        if (sav->flags & SADB_X_SAFLAGS_ESN &&
            sav->replay != NULL && sav->replay->wsize != 0) {
                seqh = htonl(seqh);
                memcpy(crp->crp_esn, &seqh, sizeof(seqh));
        }

        /* These are passed as-is to the callback. */
        xd->sav = sav;
        xd->nxt = hl;
        xd->protoff = protoff;
        xd->skip = skip;
        xd->cryptoid = cryptoid;
        xd->vnet = curvnet;
        if (V_async_crypto)
                return (crypto_dispatch_async(crp, CRYPTO_ASYNC_ORDERED));
        else
                return (crypto_dispatch(crp));
bad:
        m_freem(m);
        key_freesav(&sav);
        return (error);
}

/*
 * AH input callback from the crypto driver.
 */
static int
ah_input_cb(struct cryptop *crp)
{
        IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]);
        unsigned char calc[AH_ALEN_MAX];
        struct rm_priotracker sahtree_tracker;
        struct mbuf *m;
        struct xform_data *xd;
        struct secasvar *sav;
        struct secasindex *saidx;
        caddr_t ptr;
        crypto_session_t cryptoid;
        int authsize, rplen, ahsize, error, skip, protoff;
        uint8_t nxt;

        SECASVAR_RLOCK_TRACKER;

        m = crp->crp_buf.cb_mbuf;
        xd = crp->crp_opaque;
        CURVNET_SET(xd->vnet);
        sav = xd->sav;
        skip = xd->skip;
        nxt = xd->nxt;
        protoff = xd->protoff;
        cryptoid = xd->cryptoid;
        ipsec_sahtree_rlock(&sahtree_tracker);
        if (sav->state >= SADB_SASTATE_DEAD) {
                /* saidx is freed */
                DPRINTF(("%s: dead SA %p spi %#x\n", __func__, sav, sav->spi));
                AHSTAT_INC(ahs_notdb);
                error = ESRCH;
                goto bad;
        }
        saidx = &sav->sah->saidx;
        IPSEC_ASSERT(saidx->dst.sa.sa_family == AF_INET ||
                saidx->dst.sa.sa_family == AF_INET6,
                ("unexpected protocol family %u", saidx->dst.sa.sa_family));

        /* Check for crypto errors. */
        if (crp->crp_etype) {
                if (crp->crp_etype == EAGAIN) {
                        /* Reset the session ID */
                        if (ipsec_updateid(sav, &crp->crp_session, &cryptoid) != 0)
                                crypto_freesession(cryptoid);
                        xd->cryptoid = crp->crp_session;
                        CURVNET_RESTORE();
                        return (crypto_dispatch(crp));
                }
                AHSTAT_INC(ahs_noxform);
                DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype));
                error = crp->crp_etype;
                goto bad;
        } else {
                AHSTAT_INC2(ahs_hist, sav->alg_auth);
                crypto_freereq(crp);            /* No longer needed. */
                crp = NULL;
        }

        /* Shouldn't happen... */
        if (m == NULL) {
                AHSTAT_INC(ahs_crypto);
                DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
                error = EINVAL;
                goto bad;
        }

        /* Figure out header size. */
        rplen = HDRSIZE(sav);
        authsize = AUTHSIZE(sav);
        ahsize = ah_hdrsiz(sav);

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

        /* Verify authenticator. */
        ptr = (caddr_t) (xd + 1);
        if (timingsafe_bcmp(ptr + skip + rplen, calc, authsize)) {
                DPRINTF(("%s: authentication hash mismatch for packet "
                    "in SA %s/%08lx\n", __func__,
                    ipsec_address(&saidx->dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi)));
                AHSTAT_INC(ahs_badauth);
                error = EACCES;
                goto bad;
        }
        /* Fix the Next Protocol field. */
        ((uint8_t *) ptr)[protoff] = nxt;

        /* Copyback the saved (uncooked) network headers. */
        m_copyback(m, 0, skip, ptr);
        free(xd, M_AH), xd = NULL;                      /* No longer needed */

        /*
         * Header is now authenticated.
         */
        m->m_flags |= M_AUTHIPHDR|M_AUTHIPDGM;

        /*
         * Update replay sequence number, if appropriate.
         */
        if (sav->replay) {
                u_int32_t seq;

                m_copydata(m, skip + offsetof(struct newah, ah_seq),
                           sizeof (seq), (caddr_t) &seq);
                SECASVAR_RLOCK(sav);
                if (ipsec_updatereplay(ntohl(seq), sav)) {
                        SECASVAR_RUNLOCK(sav);
                        AHSTAT_INC(ahs_replay);
                        error = EACCES;
                        goto bad;
                }
                SECASVAR_RUNLOCK(sav);
        }

        /*
         * Remove the AH header and authenticator from the mbuf.
         */
        error = m_striphdr(m, skip, ahsize);
        if (error) {
                DPRINTF(("%s: mangled mbuf chain for SA %s/%08lx\n", __func__,
                    ipsec_address(&saidx->dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi)));
                AHSTAT_INC(ahs_hdrops);
                goto bad;
        }

        switch (saidx->dst.sa.sa_family) {
#ifdef INET6
        case AF_INET6:
                error = ipsec6_common_input_cb(m, sav, skip, protoff,
                    &sahtree_tracker);
                break;
#endif
#ifdef INET
        case AF_INET:
                error = ipsec4_common_input_cb(m, sav, skip, protoff,
                    &sahtree_tracker);
                break;
#endif
        default:
                panic("%s: Unexpected address family: %d saidx=%p", __func__,
                    saidx->dst.sa.sa_family, saidx);
        }
        CURVNET_RESTORE();
        return error;
bad:
        ipsec_sahtree_runlock(&sahtree_tracker);
        CURVNET_RESTORE();
        if (sav)
                key_freesav(&sav);
        if (m != NULL)
                m_freem(m);
        if (xd != NULL)
                free(xd, M_AH);
        if (crp != NULL)
                crypto_freereq(crp);
        return error;
}

/*
 * AH output routine, called by ipsec[46]_perform_request().
 */
static int
ah_output(struct mbuf *m, struct secpolicy *sp, struct secasvar *sav,
    u_int idx, int skip, int protoff)
{
        IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]);
        const struct auth_hash *ahx;
        struct xform_data *xd;
        struct mbuf *mi;
        struct cryptop *crp;
        struct newah *ah;
        crypto_session_t cryptoid;
        uint16_t iplen;
        int error, rplen, authsize, ahsize, maxpacketsize, roff;
        uint8_t prot;
        uint32_t seqh;

        SECASVAR_RLOCK_TRACKER;

        IPSEC_ASSERT(sav != NULL, ("null SA"));
        ahx = sav->tdb_authalgxform;
        IPSEC_ASSERT(ahx != NULL, ("null authentication xform"));

        AHSTAT_INC(ahs_output);

        /* Figure out header size. */
        rplen = HDRSIZE(sav);
        authsize = AUTHSIZE(sav);
        ahsize = ah_hdrsiz(sav);

        /* Check for maximum packet size violations. */
        switch (sav->sah->saidx.dst.sa.sa_family) {
#ifdef INET
        case AF_INET:
                maxpacketsize = IP_MAXPACKET;
                break;
#endif /* INET */
#ifdef INET6
        case AF_INET6:
                maxpacketsize = IPV6_MAXPACKET;
                break;
#endif /* INET6 */
        default:
                DPRINTF(("%s: unknown/unsupported protocol family %u, "
                    "SA %s/%08lx\n", __func__,
                    sav->sah->saidx.dst.sa.sa_family,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi)));
                AHSTAT_INC(ahs_nopf);
                error = EPFNOSUPPORT;
                goto bad;
        }
        if (ahsize + m->m_pkthdr.len > maxpacketsize) {
                DPRINTF(("%s: packet in SA %s/%08lx got too big "
                    "(len %u, max len %u)\n", __func__,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi),
                    ahsize + m->m_pkthdr.len, maxpacketsize));
                AHSTAT_INC(ahs_toobig);
                error = EMSGSIZE;
                goto bad;
        }

        /* Update the counters. */
        AHSTAT_ADD(ahs_obytes, m->m_pkthdr.len - skip);

        m = m_unshare(m, M_NOWAIT);
        if (m == NULL) {
                DPRINTF(("%s: cannot clone mbuf chain, SA %s/%08lx\n", __func__,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi)));
                AHSTAT_INC(ahs_hdrops);
                error = ENOBUFS;
                goto bad;
        }

        /* Inject AH header. */
        mi = m_makespace(m, skip, ahsize, &roff);
        if (mi == NULL) {
                DPRINTF(("%s: failed to inject %u byte AH header for SA "
                    "%s/%08lx\n", __func__, ahsize,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi)));
                AHSTAT_INC(ahs_hdrops);         /*XXX differs from openbsd */
                error = ENOBUFS;
                goto bad;
        }

        /*
         * The AH header is guaranteed by m_makespace() to be in
         * contiguous memory, at roff bytes offset into the returned mbuf.
         */
        ah = (struct newah *)(mtod(mi, caddr_t) + roff);

        /* Initialize the AH header. */
        m_copydata(m, protoff, sizeof(u_int8_t), (caddr_t) &ah->ah_nxt);
        ah->ah_len = (ahsize - sizeof(struct ah)) / sizeof(u_int32_t);
        ah->ah_reserve = 0;
        ah->ah_spi = sav->spi;

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

        /* Zeroize padding */
        m_copyback(m, skip + rplen + authsize, ahsize - (rplen + authsize),
            ipseczeroes);

        /* Insert packet replay counter, as requested.  */
        SECASVAR_RLOCK(sav);
        if (sav->replay) {
                SECREPLAY_LOCK(sav->replay);
                if ((sav->replay->count == ~0 ||
                    (!(sav->flags & SADB_X_SAFLAGS_ESN) &&
                    ((uint32_t)sav->replay->count) == ~0)) &&
                    (sav->flags & SADB_X_EXT_CYCSEQ) == 0) {
                        SECREPLAY_UNLOCK(sav->replay);
                        SECASVAR_RUNLOCK(sav);
                        DPRINTF(("%s: replay counter wrapped for SA %s/%08lx\n",
                            __func__, ipsec_address(&sav->sah->saidx.dst, buf,
                            sizeof(buf)), (u_long) ntohl(sav->spi)));
                        AHSTAT_INC(ahs_wrap);
                        error = EACCES;
                        goto bad;
                }
#ifdef REGRESSION
                /* Emulate replay attack when ipsec_replay is TRUE. */
                if (!V_ipsec_replay)
#endif
                        sav->replay->count++;
                ah->ah_seq = htonl((uint32_t)sav->replay->count);
                SECREPLAY_UNLOCK(sav->replay);
        }
        cryptoid = sav->tdb_cryptoid;
        SECASVAR_RUNLOCK(sav);

        /* Get crypto descriptors. */
        crp = crypto_getreq(cryptoid, M_NOWAIT);
        if (crp == NULL) {
                DPRINTF(("%s: failed to acquire crypto descriptors\n",
                        __func__));
                AHSTAT_INC(ahs_crypto);
                error = ENOBUFS;
                goto bad;
        }

        crp->crp_payload_start = 0;
        crp->crp_payload_length = m->m_pkthdr.len;
        crp->crp_digest_start = skip + rplen;

        /* Allocate IPsec-specific opaque crypto info. */
        xd =  malloc(sizeof(struct xform_data) + skip, M_AH,
            M_NOWAIT | M_ZERO);
        if (xd == NULL) {
                crypto_freereq(crp);
                DPRINTF(("%s: failed to allocate xform_data\n", __func__));
                AHSTAT_INC(ahs_crypto);
                error = ENOBUFS;
                goto bad;
        }

        /* Save the skipped portion of the packet. */
        m_copydata(m, 0, skip, (caddr_t) (xd + 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 (sav->sah->saidx.dst.sa.sa_family) {
#ifdef INET
        case AF_INET:
                bcopy(((caddr_t)(xd + 1)) +
                    offsetof(struct ip, ip_len),
                    (caddr_t) &iplen, sizeof(u_int16_t));
                iplen = htons(ntohs(iplen) + ahsize);
                m_copyback(m, offsetof(struct ip, ip_len),
                    sizeof(u_int16_t), (caddr_t) &iplen);
                break;
#endif /* INET */

#ifdef INET6
        case AF_INET6:
                bcopy(((caddr_t)(xd + 1)) +
                    offsetof(struct ip6_hdr, ip6_plen),
                    (caddr_t) &iplen, sizeof(uint16_t));
                iplen = htons(ntohs(iplen) + ahsize);
                m_copyback(m, offsetof(struct ip6_hdr, ip6_plen),
                    sizeof(uint16_t), (caddr_t) &iplen);
                break;
#endif /* INET6 */
        }

        /* Fix the Next Header field in saved header. */
        ((uint8_t *) (xd + 1))[protoff] = IPPROTO_AH;

        /* Update the Next Protocol field in the IP header. */
        prot = IPPROTO_AH;
        m_copyback(m, protoff, sizeof(uint8_t), (caddr_t) &prot);

        /* "Massage" the packet headers for crypto processing. */
        error = ah_massage_headers(&m, sav->sah->saidx.dst.sa.sa_family,
                        skip, ahx->type, 1);
        if (error != 0) {
                m = NULL;       /* mbuf was free'd by ah_massage_headers. */
                free(xd, M_AH);
                crypto_freereq(crp);
                goto bad;
        }

        /* Crypto operation descriptor. */
        crp->crp_op = CRYPTO_OP_COMPUTE_DIGEST;
        crp->crp_flags = CRYPTO_F_CBIFSYNC;
        crypto_use_mbuf(crp, m);
        crp->crp_callback = ah_output_cb;
        crp->crp_opaque = xd;

        if (sav->flags & SADB_X_SAFLAGS_ESN && sav->replay != NULL) {
                SECREPLAY_LOCK(sav->replay);
                seqh = htonl((uint32_t)(sav->replay->count >> IPSEC_SEQH_SHIFT));
                memcpy(crp->crp_esn, &seqh, sizeof(seqh));
                SECREPLAY_UNLOCK(sav->replay);
        }

        /* These are passed as-is to the callback. */
        xd->sp = sp;
        xd->sav = sav;
        xd->skip = skip;
        xd->idx = idx;
        xd->cryptoid = cryptoid;
        xd->vnet = curvnet;

        if (V_async_crypto)
                return (crypto_dispatch_async(crp, CRYPTO_ASYNC_ORDERED));
        else
                return (crypto_dispatch(crp));
bad:
        if (m)
                m_freem(m);
        key_freesav(&sav);
        key_freesp(&sp);
        return (error);
}

/*
 * AH output callback from the crypto driver.
 */
static int
ah_output_cb(struct cryptop *crp)
{
        struct xform_data *xd;
        struct secpolicy *sp;
        struct secasvar *sav;
        struct mbuf *m;
        crypto_session_t cryptoid;
        caddr_t ptr;
        u_int idx;
        int skip, error;

        m = crp->crp_buf.cb_mbuf;
        xd = (struct xform_data *) crp->crp_opaque;
        CURVNET_SET(xd->vnet);
        sp = xd->sp;
        sav = xd->sav;
        skip = xd->skip;
        idx = xd->idx;
        cryptoid = xd->cryptoid;
        ptr = (caddr_t) (xd + 1);

        /* Check for crypto errors. */
        if (crp->crp_etype) {
                if (crp->crp_etype == EAGAIN) {
                        /* Reset the session ID */
                        if (ipsec_updateid(sav, &crp->crp_session, &cryptoid) != 0)
                                crypto_freesession(cryptoid);
                        xd->cryptoid = crp->crp_session;
                        CURVNET_RESTORE();
                        return (crypto_dispatch(crp));
                }
                AHSTAT_INC(ahs_noxform);
                DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype));
                error = crp->crp_etype;
                m_freem(m);
                goto bad;
        }

        /* Shouldn't happen... */
        if (m == NULL) {
                AHSTAT_INC(ahs_crypto);
                DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
                error = EINVAL;
                goto bad;
        }
        /*
         * Copy original headers (with the new protocol number) back
         * in place.
         */
        m_copyback(m, 0, skip, ptr);

        free(xd, M_AH);
        crypto_freereq(crp);
        AHSTAT_INC2(ahs_hist, sav->alg_auth);
#ifdef REGRESSION
        /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */
        if (V_ipsec_integrity) {
                int alen;

                /*
                 * Corrupt HMAC if we want to test integrity verification of
                 * the other side.
                 */
                alen = AUTHSIZE(sav);
                m_copyback(m, m->m_pkthdr.len - alen, alen, ipseczeroes);
        }
#endif

        /* NB: m is reclaimed by ipsec_process_done. */
        error = ipsec_process_done(m, sp, sav, idx);
        CURVNET_RESTORE();
        return (error);
bad:
        CURVNET_RESTORE();
        free(xd, M_AH);
        crypto_freereq(crp);
        key_freesav(&sav);
        key_freesp(&sp);
        return (error);
}

static struct xformsw ah_xformsw = {
        .xf_type =      XF_AH,
        .xf_name =      "IPsec AH",
        .xf_init =      ah_init,
        .xf_cleanup =   ah_cleanup,
        .xf_input =     ah_input,
        .xf_output =    ah_output,
};

SYSINIT(ah_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE,
    xform_attach, &ah_xformsw);
SYSUNINIT(ah_xform_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE,
    xform_detach, &ah_xformsw);