/*
 * Copyright (C) 2012 by Darren Reed.
 *
 * See the IPFILTER.LICENCE file for details on licencing.
 *
 * Simple ISAKMP transparent proxy for in-kernel use.  For use with the NAT
 * code.
 *
 * $Id$
 *
 */
#define IPF_IPSEC_PROXY


/*
 * IPSec proxy
 */
typedef struct ipf_ipsec_softc_s {
        frentry_t       ipsec_fr;
        int             ipsec_proxy_init;
        int             ipsec_proxy_ttl;
        ipftq_t         *ipsec_nat_tqe;
        ipftq_t         *ipsec_state_tqe;
        char            ipsec_buffer[1500];
} ipf_ipsec_softc_t;


void *ipf_p_ipsec_soft_create(ipf_main_softc_t *);
void ipf_p_ipsec_soft_destroy(ipf_main_softc_t *, void *);
int ipf_p_ipsec_soft_init(ipf_main_softc_t *, void *);
void ipf_p_ipsec_soft_fini(ipf_main_softc_t *, void *);
int ipf_p_ipsec_init(void);
void ipf_p_ipsec_fini(void);
int ipf_p_ipsec_new(void *, fr_info_t *, ap_session_t *, nat_t *);
void ipf_p_ipsec_del(ipf_main_softc_t *, ap_session_t *);
int ipf_p_ipsec_inout(void *, fr_info_t *, ap_session_t *, nat_t *);
int ipf_p_ipsec_match(fr_info_t *, ap_session_t *, nat_t *);


/*
 * IPSec application proxy initialization.
 */
void *
ipf_p_ipsec_soft_create(ipf_main_softc_t *softc)
{
        ipf_ipsec_softc_t *softi;

        KMALLOC(softi, ipf_ipsec_softc_t *);
        if (softi == NULL)
                return (NULL);

        bzero((char *)softi, sizeof(*softi));
        softi->ipsec_fr.fr_ref = 1;
        softi->ipsec_fr.fr_flags = FR_OUTQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
        MUTEX_INIT(&softi->ipsec_fr.fr_lock, "IPsec proxy rule lock");
        softi->ipsec_proxy_init = 1;
        softi->ipsec_proxy_ttl = 60;

        return (softi);
}


int
ipf_p_ipsec_soft_init(ipf_main_softc_t *softc, void *arg)
{
        ipf_ipsec_softc_t *softi = arg;

        softi->ipsec_nat_tqe = ipf_state_add_tq(softc, softi->ipsec_proxy_ttl);
        if (softi->ipsec_nat_tqe == NULL)
                return (-1);
        softi->ipsec_state_tqe = ipf_nat_add_tq(softc, softi->ipsec_proxy_ttl);
        if (softi->ipsec_state_tqe == NULL) {
                if (ipf_deletetimeoutqueue(softi->ipsec_nat_tqe) == 0)
                        ipf_freetimeoutqueue(softc, softi->ipsec_nat_tqe);
                softi->ipsec_nat_tqe = NULL;
                return (-1);
        }

        softi->ipsec_nat_tqe->ifq_flags |= IFQF_PROXY;
        softi->ipsec_state_tqe->ifq_flags |= IFQF_PROXY;
        softi->ipsec_fr.fr_age[0] = softi->ipsec_proxy_ttl;
        softi->ipsec_fr.fr_age[1] = softi->ipsec_proxy_ttl;
        return (0);
}


void
ipf_p_ipsec_soft_fini(ipf_main_softc_t *softc, void *arg)
{
        ipf_ipsec_softc_t *softi = arg;

        if (arg == NULL)
                return;

        if (softi->ipsec_nat_tqe != NULL) {
                if (ipf_deletetimeoutqueue(softi->ipsec_nat_tqe) == 0)
                        ipf_freetimeoutqueue(softc, softi->ipsec_nat_tqe);
        }
        softi->ipsec_nat_tqe = NULL;
        if (softi->ipsec_state_tqe != NULL) {
                if (ipf_deletetimeoutqueue(softi->ipsec_state_tqe) == 0)
                        ipf_freetimeoutqueue(softc, softi->ipsec_state_tqe);
        }
        softi->ipsec_state_tqe = NULL;
}


void
ipf_p_ipsec_soft_destroy(ipf_main_softc_t *softc, void *arg)
{
        ipf_ipsec_softc_t *softi = arg;

        if (softi->ipsec_proxy_init == 1) {
                MUTEX_DESTROY(&softi->ipsec_fr.fr_lock);
                softi->ipsec_proxy_init = 0;
        }

        KFREE(softi);
}


/*
 * Setup for a new IPSEC proxy.
 */
int
ipf_p_ipsec_new(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat)
{
        ipf_ipsec_softc_t *softi = arg;
        ipf_main_softc_t *softc = fin->fin_main_soft;
#ifdef USE_MUTEXES
        ipf_nat_softc_t *softn = softc->ipf_nat_soft;
#endif
        int p, off, dlen, ttl;
        ipsec_pxy_t *ipsec;
        ipnat_t *ipn, *np;
        fr_info_t fi;
        char *ptr;
        int size;
        ip_t *ip;
        mb_t *m;

        if (fin->fin_v != 4)
                return (-1);

        off = fin->fin_plen - fin->fin_dlen + fin->fin_ipoff;
        bzero(softi->ipsec_buffer, sizeof(softi->ipsec_buffer));
        ip = fin->fin_ip;
        m = fin->fin_m;

        dlen = M_LEN(m) - off;
        if (dlen < 16)
                return (-1);
        COPYDATA(m, off, MIN(sizeof(softi->ipsec_buffer), dlen),
                 softi->ipsec_buffer);

        if (ipf_nat_outlookup(fin, 0, IPPROTO_ESP, nat->nat_nsrcip,
                          ip->ip_dst) != NULL)
                return (-1);

        np = nat->nat_ptr;
        size = np->in_size;
        KMALLOC(ipsec, ipsec_pxy_t *);
        if (ipsec == NULL)
                return (-1);

        KMALLOCS(ipn, ipnat_t *, size);
        if (ipn == NULL) {
                KFREE(ipsec);
                return (-1);
        }

        aps->aps_data = ipsec;
        aps->aps_psiz = sizeof(*ipsec);
        bzero((char *)ipsec, sizeof(*ipsec));
        bzero((char *)ipn, size);
        ipsec->ipsc_rule = ipn;

        /*
         * Create NAT rule against which the tunnel/transport mapping is
         * created.  This is required because the current NAT rule does not
         * describe ESP but UDP instead.
         */
        ipn->in_size = size;
        ttl = IPF_TTLVAL(softi->ipsec_nat_tqe->ifq_ttl);
        ipn->in_tqehead[0] = ipf_nat_add_tq(softc, ttl);
        ipn->in_tqehead[1] = ipf_nat_add_tq(softc, ttl);
        ipn->in_ifps[0] = fin->fin_ifp;
        ipn->in_apr = NULL;
        ipn->in_use = 1;
        ipn->in_hits = 1;
        ipn->in_snip = ntohl(nat->nat_nsrcaddr);
        ipn->in_ippip = 1;
        ipn->in_osrcip = nat->nat_osrcip;
        ipn->in_osrcmsk = 0xffffffff;
        ipn->in_nsrcip = nat->nat_nsrcip;
        ipn->in_nsrcmsk = 0xffffffff;
        ipn->in_odstip = nat->nat_odstip;
        ipn->in_odstmsk = 0xffffffff;
        ipn->in_ndstip = nat->nat_ndstip;
        ipn->in_ndstmsk = 0xffffffff;
        ipn->in_redir = NAT_MAP;
        ipn->in_pr[0] = IPPROTO_ESP;
        ipn->in_pr[1] = IPPROTO_ESP;
        ipn->in_flags = (np->in_flags | IPN_PROXYRULE);
        MUTEX_INIT(&ipn->in_lock, "IPSec proxy NAT rule");

        ipn->in_namelen = np->in_namelen;
        bcopy(np->in_names, ipn->in_ifnames, ipn->in_namelen);
        ipn->in_ifnames[0] = np->in_ifnames[0];
        ipn->in_ifnames[1] = np->in_ifnames[1];

        bcopy((char *)fin, (char *)&fi, sizeof(fi));
        fi.fin_fi.fi_p = IPPROTO_ESP;
        fi.fin_fr = &softi->ipsec_fr;
        fi.fin_data[0] = 0;
        fi.fin_data[1] = 0;
        p = ip->ip_p;
        ip->ip_p = IPPROTO_ESP;
        fi.fin_flx &= ~(FI_TCPUDP|FI_STATE|FI_FRAG);
        fi.fin_flx |= FI_IGNORE;

        ptr = softi->ipsec_buffer;
        bcopy(ptr, (char *)ipsec->ipsc_icookie, sizeof(ipsec_cookie_t));
        ptr += sizeof(ipsec_cookie_t);
        bcopy(ptr, (char *)ipsec->ipsc_rcookie, sizeof(ipsec_cookie_t));
        /*
         * The responder cookie should only be non-zero if the initiator
         * cookie is non-zero.  Therefore, it is safe to assume(!) that the
         * cookies are both set after copying if the responder is non-zero.
         */
        if ((ipsec->ipsc_rcookie[0]|ipsec->ipsc_rcookie[1]) != 0)
                ipsec->ipsc_rckset = 1;

        MUTEX_ENTER(&softn->ipf_nat_new);
        ipsec->ipsc_nat = ipf_nat_add(&fi, ipn, &ipsec->ipsc_nat,
                                      NAT_SLAVE|SI_WILDP, NAT_OUTBOUND);
        MUTEX_EXIT(&softn->ipf_nat_new);
        if (ipsec->ipsc_nat != NULL) {
                (void) ipf_nat_proto(&fi, ipsec->ipsc_nat, 0);
                MUTEX_ENTER(&ipsec->ipsc_nat->nat_lock);
                ipf_nat_update(&fi, ipsec->ipsc_nat);
                MUTEX_EXIT(&ipsec->ipsc_nat->nat_lock);

                fi.fin_data[0] = 0;
                fi.fin_data[1] = 0;
                (void) ipf_state_add(softc, &fi, &ipsec->ipsc_state, SI_WILDP);
        }
        ip->ip_p = p & 0xff;
        return (0);
}


/*
 * For outgoing IKE packets.  refresh timeouts for NAT & state entries, if
 * we can.  If they have disappeared, recreate them.
 */
int
ipf_p_ipsec_inout(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat)
{
        ipf_ipsec_softc_t *softi = arg;
        ipf_main_softc_t *softc = fin->fin_main_soft;
        ipsec_pxy_t *ipsec;
        fr_info_t fi;
        ip_t *ip;
        int p;

        if ((fin->fin_out == 1) && (nat->nat_dir == NAT_INBOUND))
                return (0);

        if ((fin->fin_out == 0) && (nat->nat_dir == NAT_OUTBOUND))
                return (0);

        ipsec = aps->aps_data;

        if (ipsec != NULL) {
                ip = fin->fin_ip;
                p = ip->ip_p;

                if ((ipsec->ipsc_nat == NULL) || (ipsec->ipsc_state == NULL)) {
                        bcopy((char *)fin, (char *)&fi, sizeof(fi));
                        fi.fin_fi.fi_p = IPPROTO_ESP;
                        fi.fin_fr = &softi->ipsec_fr;
                        fi.fin_data[0] = 0;
                        fi.fin_data[1] = 0;
                        ip->ip_p = IPPROTO_ESP;
                        fi.fin_flx &= ~(FI_TCPUDP|FI_STATE|FI_FRAG);
                        fi.fin_flx |= FI_IGNORE;
                }

                /*
                 * Update NAT timeout/create NAT if missing.
                 */
                if (ipsec->ipsc_nat != NULL)
                        ipf_queueback(softc->ipf_ticks,
                                      &ipsec->ipsc_nat->nat_tqe);
                else {
#ifdef USE_MUTEXES
                        ipf_nat_softc_t *softn = softc->ipf_nat_soft;
#endif

                        MUTEX_ENTER(&softn->ipf_nat_new);
                        ipsec->ipsc_nat = ipf_nat_add(&fi, ipsec->ipsc_rule,
                                                      &ipsec->ipsc_nat,
                                                      NAT_SLAVE|SI_WILDP,
                                                      nat->nat_dir);
                        MUTEX_EXIT(&softn->ipf_nat_new);
                        if (ipsec->ipsc_nat != NULL) {
                                (void) ipf_nat_proto(&fi, ipsec->ipsc_nat, 0);
                                MUTEX_ENTER(&ipsec->ipsc_nat->nat_lock);
                                ipf_nat_update(&fi, ipsec->ipsc_nat);
                                MUTEX_EXIT(&ipsec->ipsc_nat->nat_lock);
                        }
                }

                /*
                 * Update state timeout/create state if missing.
                 */
                READ_ENTER(&softc->ipf_state);
                if (ipsec->ipsc_state != NULL) {
                        ipf_queueback(softc->ipf_ticks,
                                      &ipsec->ipsc_state->is_sti);
                        ipsec->ipsc_state->is_die = nat->nat_age;
                        RWLOCK_EXIT(&softc->ipf_state);
                } else {
                        RWLOCK_EXIT(&softc->ipf_state);
                        fi.fin_data[0] = 0;
                        fi.fin_data[1] = 0;
                        (void) ipf_state_add(softc, &fi, &ipsec->ipsc_state,
                                             SI_WILDP);
                }
                ip->ip_p = p;
        }
        return (0);
}


/*
 * This extends the NAT matching to be based on the cookies associated with
 * a session and found at the front of IKE packets.  The cookies are always
 * in the same order (not reversed depending on packet flow direction as with
 * UDP/TCP port numbers).
 */
int
ipf_p_ipsec_match(fr_info_t *fin, ap_session_t *aps, nat_t *nat __unused)
{
        ipsec_pxy_t *ipsec;
        u_32_t cookies[4];
        mb_t *m;
        int off;

        if ((fin->fin_dlen < sizeof(cookies)) || (fin->fin_flx & FI_FRAG))
                return (-1);

        off = fin->fin_plen - fin->fin_dlen + fin->fin_ipoff;
        ipsec = aps->aps_data;
        m = fin->fin_m;
        COPYDATA(m, off, sizeof(cookies), (char *)cookies);

        if ((cookies[0] != ipsec->ipsc_icookie[0]) ||
            (cookies[1] != ipsec->ipsc_icookie[1]))
                return (-1);

        if (ipsec->ipsc_rckset == 0) {
                if ((cookies[2]|cookies[3]) == 0) {
                        return (0);
                }
                ipsec->ipsc_rckset = 1;
                ipsec->ipsc_rcookie[0] = cookies[2];
                ipsec->ipsc_rcookie[1] = cookies[3];
                return (0);
        }

        if ((cookies[2] != ipsec->ipsc_rcookie[0]) ||
            (cookies[3] != ipsec->ipsc_rcookie[1]))
                return (-1);
        return (0);
}


/*
 * clean up after ourselves.
 */
void
ipf_p_ipsec_del(ipf_main_softc_t *softc, ap_session_t *aps)
{
        ipsec_pxy_t *ipsec;

        ipsec = aps->aps_data;

        if (ipsec != NULL) {
                /*
                 * Don't bother changing any of the NAT structure details,
                 * *_del() is on a callback from aps_free(), from nat_delete()
                 */

                READ_ENTER(&softc->ipf_state);
                if (ipsec->ipsc_state != NULL) {
                        ipsec->ipsc_state->is_die = softc->ipf_ticks + 1;
                        ipsec->ipsc_state->is_me = NULL;
                        ipf_queuefront(&ipsec->ipsc_state->is_sti);
                }
                RWLOCK_EXIT(&softc->ipf_state);

                ipsec->ipsc_state = NULL;
                ipsec->ipsc_nat = NULL;
                ipsec->ipsc_rule->in_flags |= IPN_DELETE;
                ipf_nat_rule_deref(softc, &ipsec->ipsc_rule);
        }
}