/*      $FreeBSD: src/sys/netinet6/ip6_fw.c,v 1.2.2.10 2003/08/03 17:52:54 ume Exp $    */
/*      $KAME: ip6_fw.c,v 1.21 2001/01/24 01:25:32 itojun Exp $ */

/*
 * Copyright (C) 1998, 1999, 2000 and 2001 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 1993 Daniel Boulet
 * Copyright (c) 1994 Ugen J.S.Antsilevich
 * Copyright (c) 1996 Alex Nash
 *
 * Redistribution and use in source forms, with and without modification,
 * are permitted provided that this entire comment appears intact.
 *
 * Redistribution in binary form may occur without any restrictions.
 * Obviously, it would be nice if you gave credit where credit is due
 * but requiring it would be too onerous.
 *
 * This software is provided ``AS IS'' without any warranties of any kind.
 */

/*
 * Implement IPv6 packet firewall
 */

#if !defined(KLD_MODULE)
#include "opt_ip6fw.h"
#include "opt_inet.h"
#include "opt_inet6.h"
#endif

#ifdef IP6DIVERT
#error "NOT SUPPORTED IPV6 DIVERT"
#endif
#ifdef IP6FW_DIVERT_RESTART
#error "NOT SUPPORTED IPV6 DIVERT"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/queue.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/syslog.h>
#include <sys/thread2.h>
#include <sys/time.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>

#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_var.h>
#include <netinet/icmp6.h>

#include <netinet/in_pcb.h>

#include "ip6_fw.h"
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/udp.h>

#include <sys/sysctl.h>

#include <net/net_osdep.h>

MALLOC_DEFINE(M_IP6FW, "Ip6Fw/Ip6Acct", "Ip6Fw/Ip6Acct chain's");

static int fw6_debug = 1;
#ifdef IPV6FIREWALL_VERBOSE
static int fw6_verbose = 1;
#else
static int fw6_verbose = 0;
#endif
#ifdef IPV6FIREWALL_VERBOSE_LIMIT
static int fw6_verbose_limit = IPV6FIREWALL_VERBOSE_LIMIT;
#else
static int fw6_verbose_limit = 0;
#endif

LIST_HEAD (ip6_fw_head, ip6_fw_chain) ip6_fw_chain;

#ifdef SYSCTL_NODE
SYSCTL_DECL(_net_inet6_ip6);
SYSCTL_NODE(_net_inet6_ip6, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall");
SYSCTL_INT(_net_inet6_ip6_fw, OID_AUTO, enable, CTLFLAG_RW,
        &ip6_fw_enable, 0, "Enable ip6fw");
SYSCTL_INT(_net_inet6_ip6_fw, OID_AUTO, debug, CTLFLAG_RW, &fw6_debug, 0, "");
SYSCTL_INT(_net_inet6_ip6_fw, OID_AUTO, verbose, CTLFLAG_RW, &fw6_verbose, 0, "");
SYSCTL_INT(_net_inet6_ip6_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, &fw6_verbose_limit, 0, "");
#endif

#define dprintf(a)      do {                                            \
                                if (fw6_debug)                          \
                                        kprintf a;                      \
                        } while (0)
#define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0

static int      add_entry6 (struct ip6_fw_head *chainptr, struct ip6_fw *frwl);
static int      del_entry6 (struct ip6_fw_head *chainptr, u_short number);
static int      zero_entry6 (struct mbuf *m);
static struct ip6_fw *check_ip6fw_struct (struct ip6_fw *m);
static struct ip6_fw *check_ip6fw_mbuf (struct mbuf *fw);
static int      ip6opts_match (struct ip6_hdr **ip6, struct ip6_fw *f,
                                   struct mbuf **m,
                                   int *off, int *nxt, u_short *offset);
static int      port_match6 (u_short *portptr, int nports, u_short port,
                                int range_flag);
static int      tcp6flg_match (struct tcphdr *tcp6, struct ip6_fw *f);
static int      icmp6type_match (struct icmp6_hdr *  icmp, struct ip6_fw * f);
static void     ip6fw_report (struct ip6_fw *f, struct ip6_hdr *ip6,
                                struct ifnet *rif, struct ifnet *oif, int off, int nxt);

static int      ip6_fw_chk (struct ip6_hdr **pip6,
                        struct ifnet *oif, u_int16_t *cookie, struct mbuf **m);
static int      ip6_fw_ctl (int stage, struct mbuf **mm);

static char err_prefix[] = "ip6_fw_ctl:";

/*
 * Returns 1 if the port is matched by the vector, 0 otherwise
 */
static __inline int
port_match6(u_short *portptr, int nports, u_short port, int range_flag)
{
        if (!nports)
                return 1;
        if (range_flag) {
                if (portptr[0] <= port && port <= portptr[1]) {
                        return 1;
                }
                nports -= 2;
                portptr += 2;
        }
        while (nports-- > 0) {
                if (*portptr++ == port) {
                        return 1;
                }
        }
        return 0;
}

static int
tcp6flg_match(struct tcphdr *tcp6, struct ip6_fw *f)
{
        u_char          flg_set, flg_clr;

        /*
         * If an established connection is required, reject packets that
         * have only SYN of RST|ACK|SYN set.  Otherwise, fall through to
         * other flag requirements.
         */
        if ((f->fw_ipflg & IPV6_FW_IF_TCPEST) &&
            ((tcp6->th_flags & (IPV6_FW_TCPF_RST | IPV6_FW_TCPF_ACK |
            IPV6_FW_TCPF_SYN)) == IPV6_FW_TCPF_SYN))
                return 0;

        flg_set = tcp6->th_flags & f->fw_tcpf;
        flg_clr = tcp6->th_flags & f->fw_tcpnf;

        if (flg_set != f->fw_tcpf)
                return 0;
        if (flg_clr)
                return 0;

        return 1;
}

static int
icmp6type_match(struct icmp6_hdr *icmp6, struct ip6_fw *f)
{
        int type;

        if (!(f->fw_flg & IPV6_FW_F_ICMPBIT))
                return(1);

        type = icmp6->icmp6_type;

        /* check for matching type in the bitmap */
        if (type < IPV6_FW_ICMPTYPES_DIM * sizeof(unsigned) * 8 &&
                (f->fw_icmp6types[type / (sizeof(unsigned) * 8)] &
                (1U << (type % (8 * sizeof(unsigned))))))
                return(1);

        return(0); /* no match */
}

static int
is_icmp6_query(struct ip6_hdr *ip6, int off)
{
        const struct icmp6_hdr *icmp6;
        int icmp6_type;

        icmp6 = (struct icmp6_hdr *)((caddr_t)ip6 + off);
        icmp6_type = icmp6->icmp6_type;

        if (icmp6_type == ICMP6_ECHO_REQUEST ||
            icmp6_type == ICMP6_MEMBERSHIP_QUERY ||
            icmp6_type == ICMP6_WRUREQUEST ||
            icmp6_type == ICMP6_FQDN_QUERY ||
            icmp6_type == ICMP6_NI_QUERY)
                return(1);

        return(0);
}

static int
ip6opts_match(struct ip6_hdr **pip6, struct ip6_fw *f, struct mbuf **m,
              int *off, int *nxt, u_short *offset)
{
        int len;
        struct ip6_hdr *ip6 = *pip6;
        struct ip6_ext *ip6e;
        u_char  opts, nopts, nopts_sve;

        opts = f->fw_ip6opt;
        nopts = nopts_sve = f->fw_ip6nopt;

        *nxt = ip6->ip6_nxt;
        *off = sizeof(struct ip6_hdr);
        len = ntohs(ip6->ip6_plen) + sizeof(struct ip6_hdr);
        while (*off < len) {
                ip6e = (struct ip6_ext *)((caddr_t) ip6 + *off);
                if ((*m)->m_len < *off + sizeof(*ip6e))
                        goto opts_check;        /* XXX */

                switch (*nxt) {
                case IPPROTO_FRAGMENT:
                        if ((*m)->m_len >= *off + sizeof(struct ip6_frag)) {
                                struct ip6_frag *ip6f;

                                ip6f = (struct ip6_frag *) ((caddr_t)ip6 + *off);
                                *offset = ip6f->ip6f_offlg & IP6F_OFF_MASK;
                        }
                        opts &= ~IPV6_FW_IP6OPT_FRAG;
                        nopts &= ~IPV6_FW_IP6OPT_FRAG;
                        *off += sizeof(struct ip6_frag);
                        break;
                case IPPROTO_AH:
                        opts &= ~IPV6_FW_IP6OPT_AH;
                        nopts &= ~IPV6_FW_IP6OPT_AH;
                        *off += (ip6e->ip6e_len + 2) << 2;
                        break;
                default:
                        switch (*nxt) {
                        case IPPROTO_HOPOPTS:
                                opts &= ~IPV6_FW_IP6OPT_HOPOPT;
                                nopts &= ~IPV6_FW_IP6OPT_HOPOPT;
                                break;
                        case IPPROTO_ROUTING:
                                opts &= ~IPV6_FW_IP6OPT_ROUTE;
                                nopts &= ~IPV6_FW_IP6OPT_ROUTE;
                                break;
                        case IPPROTO_ESP:
                                opts &= ~IPV6_FW_IP6OPT_ESP;
                                nopts &= ~IPV6_FW_IP6OPT_ESP;
                                goto opts_check;
                        case IPPROTO_NONE:
                                opts &= ~IPV6_FW_IP6OPT_NONXT;
                                nopts &= ~IPV6_FW_IP6OPT_NONXT;
                                goto opts_check;
                        case IPPROTO_DSTOPTS:
                                opts &= ~IPV6_FW_IP6OPT_OPTS;
                                nopts &= ~IPV6_FW_IP6OPT_OPTS;
                                break;
                        default:
                                goto opts_check;
                        }
                        *off += (ip6e->ip6e_len + 1) << 3;
                        break;
                }
                *nxt = ip6e->ip6e_nxt;

        }
 opts_check:
        if (f->fw_ip6opt == f->fw_ip6nopt)      /* XXX */
                return 1;

        if (opts == 0 && nopts == nopts_sve)
                return 1;
        else
                return 0;
}

static __inline int
iface_match(struct ifnet *ifp, union ip6_fw_if *ifu, int byname)
{
        /* Check by name or by IP address */
        if (byname) {
                /* Check name */
                if (ifu->fu_via_if.glob) {
                        if (kfnmatch(ifu->fu_via_if.name, ifp->if_xname, 0)
                            == FNM_NOMATCH)
                                return(0);
                } else {
                        if (strncmp(ifp->if_xname, ifu->fu_via_if.name,
                            IP6FW_IFNLEN) != 0)
                                return(0);
                }
                return(1);
        } else if (!IN6_IS_ADDR_UNSPECIFIED(&ifu->fu_via_ip6)) {        /* Zero == wildcard */
                struct ifaddr_container *ifac;

                TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                        struct ifaddr *ifa = ifac->ifa;

                        if (ifa->ifa_addr == NULL)
                                continue;
                        if (ifa->ifa_addr->sa_family != AF_INET6)
                                continue;
                        if (!IN6_ARE_ADDR_EQUAL(&ifu->fu_via_ip6,
                            &(((struct sockaddr_in6 *)
                            (ifa->ifa_addr))->sin6_addr)))
                                continue;
                        return(1);
                }
                return(0);
        }
        return(1);
}

static void
ip6fw_report(struct ip6_fw *f, struct ip6_hdr *ip6,
        struct ifnet *rif, struct ifnet *oif, int off, int nxt)
{
        static int counter;
        struct tcphdr *const tcp6 = (struct tcphdr *) ((caddr_t) ip6+ off);
        struct udphdr *const udp = (struct udphdr *) ((caddr_t) ip6+ off);
        struct icmp6_hdr *const icmp6 = (struct icmp6_hdr *) ((caddr_t) ip6+ off);
        int count;
        char *action;
        char action2[32], proto[102], name[18];
        int len;

        count = f ? f->fw_pcnt : ++counter;
        if (fw6_verbose_limit != 0 && count > fw6_verbose_limit)
                return;

        /* Print command name */
        ksnprintf(SNPARGS(name, 0), "ip6fw: %d", f ? f->fw_number : -1);

        action = action2;
        if (!f)
                action = "Refuse";
        else {
                switch (f->fw_flg & IPV6_FW_F_COMMAND) {
                case IPV6_FW_F_DENY:
                        action = "Deny";
                        break;
                case IPV6_FW_F_REJECT:
                        if (f->fw_reject_code == IPV6_FW_REJECT_RST)
                                action = "Reset";
                        else
                                action = "Unreach";
                        break;
                case IPV6_FW_F_ACCEPT:
                        action = "Accept";
                        break;
                case IPV6_FW_F_COUNT:
                        action = "Count";
                        break;
                case IPV6_FW_F_DIVERT:
                        ksnprintf(SNPARGS(action2, 0), "Divert %d",
                            f->fw_divert_port);
                        break;
                case IPV6_FW_F_TEE:
                        ksnprintf(SNPARGS(action2, 0), "Tee %d",
                            f->fw_divert_port);
                        break;
                case IPV6_FW_F_SKIPTO:
                        ksnprintf(SNPARGS(action2, 0), "SkipTo %d",
                            f->fw_skipto_rule);
                        break;
                default:
                        action = "UNKNOWN";
                        break;
                }
        }

        switch (nxt) {
        case IPPROTO_TCP:
                len = ksnprintf(SNPARGS(proto, 0), "TCP [%s]",
                    ip6_sprintf(&ip6->ip6_src));
                if (off > 0)
                        len += ksnprintf(SNPARGS(proto, len), ":%d ",
                            ntohs(tcp6->th_sport));
                else
                        len += ksnprintf(SNPARGS(proto, len), " ");
                len += ksnprintf(SNPARGS(proto, len), "[%s]",
                    ip6_sprintf(&ip6->ip6_dst));
                if (off > 0)
                        ksnprintf(SNPARGS(proto, len), ":%d",
                            ntohs(tcp6->th_dport));
                break;
        case IPPROTO_UDP:
                len = ksnprintf(SNPARGS(proto, 0), "UDP [%s]",
                    ip6_sprintf(&ip6->ip6_src));
                if (off > 0)
                        len += ksnprintf(SNPARGS(proto, len), ":%d ",
                            ntohs(udp->uh_sport));
                else
                    len += ksnprintf(SNPARGS(proto, len), " ");
                len += ksnprintf(SNPARGS(proto, len), "[%s]",
                    ip6_sprintf(&ip6->ip6_dst));
                if (off > 0)
                        ksnprintf(SNPARGS(proto, len), ":%d",
                            ntohs(udp->uh_dport));
                break;
        case IPPROTO_ICMPV6:
                if (off > 0)
                        len = ksnprintf(SNPARGS(proto, 0), "IPV6-ICMP:%u.%u ",
                            icmp6->icmp6_type, icmp6->icmp6_code);
                else
                        len = ksnprintf(SNPARGS(proto, 0), "IPV6-ICMP ");
                len += ksnprintf(SNPARGS(proto, len), "[%s]",
                    ip6_sprintf(&ip6->ip6_src));
                ksnprintf(SNPARGS(proto, len), " [%s]",
                    ip6_sprintf(&ip6->ip6_dst));
                break;
        default:
                len = ksnprintf(SNPARGS(proto, 0), "P:%d [%s]", nxt,
                    ip6_sprintf(&ip6->ip6_src));
                ksnprintf(SNPARGS(proto, len), " [%s]",
                    ip6_sprintf(&ip6->ip6_dst));
                break;
        }

        if (oif)
                log(LOG_SECURITY | LOG_INFO, "%s %s %s out via %s\n",
                    name, action, proto, if_name(oif));
        else if (rif)
                log(LOG_SECURITY | LOG_INFO, "%s %s %s in via %s\n",
                    name, action, proto, if_name(rif));
        else
                log(LOG_SECURITY | LOG_INFO, "%s %s %s",
                    name, action, proto);
        if (fw6_verbose_limit != 0 && count == fw6_verbose_limit)
            log(LOG_SECURITY | LOG_INFO, "ip6fw: limit reached on entry %d\n",
                f ? f->fw_number : -1);
}

/*
 * Parameters:
 *
 *      ip      Pointer to packet header (struct ip6_hdr *)
 *      hlen    Packet header length
 *      oif     Outgoing interface, or NULL if packet is incoming
 * #ifndef IP6FW_DIVERT_RESTART
 *      *cookie Ignore all divert/tee rules to this port (if non-zero)
 * #else
 *      *cookie Skip up to the first rule past this rule number;
 * #endif
 *      *m      The packet; we set to NULL when/if we nuke it.
 *
 * Return value:
 *
 *      0       The packet is to be accepted and routed normally OR
 *              the packet was denied/rejected and has been dropped;
 *              in the latter case, *m is equal to NULL upon return.
 *      port    Divert the packet to port.
 */

static int
ip6_fw_chk(struct ip6_hdr **pip6,
        struct ifnet *oif, u_int16_t *cookie, struct mbuf **m)
{
        struct ip6_fw_chain *chain;
        struct ip6_fw *rule = NULL;
        struct ip6_hdr *ip6 = *pip6;
        struct ifnet *const rif = (*m)->m_pkthdr.rcvif;
        u_short offset = 0;
        int off = sizeof(struct ip6_hdr), nxt = ip6->ip6_nxt;
        u_short src_port, dst_port;
#ifdef  IP6FW_DIVERT_RESTART
        u_int16_t skipto = *cookie;
#else
        u_int16_t ignport = ntohs(*cookie);
#endif

        *cookie = 0;
        /*
         * Go down the chain, looking for enlightment
         * #ifdef IP6FW_DIVERT_RESTART
         * If we've been asked to start at a given rule immediatly, do so.
         * #endif
         */
        chain = LIST_FIRST(&ip6_fw_chain);
#ifdef IP6FW_DIVERT_RESTART
        if (skipto) {
                if (skipto >= 65535)
                        goto dropit;
                while (chain && (chain->rule->fw_number <= skipto)) {
                        chain = LIST_NEXT(chain, chain);
                }
                if (! chain) goto dropit;
        }
#endif /* IP6FW_DIVERT_RESTART */
        for (; chain; chain = LIST_NEXT(chain, chain)) {
                struct ip6_fw *const f = chain->rule;

                if (oif) {
                        /* Check direction outbound */
                        if (!(f->fw_flg & IPV6_FW_F_OUT))
                                continue;
                } else {
                        /* Check direction inbound */
                        if (!(f->fw_flg & IPV6_FW_F_IN))
                                continue;
                }

#define IN6_ARE_ADDR_MASKEQUAL(x,y,z) (\
        (((x)->s6_addr32[0] & (y)->s6_addr32[0]) == (z)->s6_addr32[0]) && \
        (((x)->s6_addr32[1] & (y)->s6_addr32[1]) == (z)->s6_addr32[1]) && \
        (((x)->s6_addr32[2] & (y)->s6_addr32[2]) == (z)->s6_addr32[2]) && \
        (((x)->s6_addr32[3] & (y)->s6_addr32[3]) == (z)->s6_addr32[3]))

                /* If src-addr doesn't match, not this rule. */
                if (((f->fw_flg & IPV6_FW_F_INVSRC) != 0) ^
                        (!IN6_ARE_ADDR_MASKEQUAL(&ip6->ip6_src,&f->fw_smsk,&f->fw_src)))
                        continue;

                /* If dest-addr doesn't match, not this rule. */
                if (((f->fw_flg & IPV6_FW_F_INVDST) != 0) ^
                        (!IN6_ARE_ADDR_MASKEQUAL(&ip6->ip6_dst,&f->fw_dmsk,&f->fw_dst)))
                        continue;

#undef IN6_ARE_ADDR_MASKEQUAL
                /* Interface check */
                if ((f->fw_flg & IF6_FW_F_VIAHACK) == IF6_FW_F_VIAHACK) {
                        struct ifnet *const iface = oif ? oif : rif;

                        /* Backwards compatibility hack for "via" */
                        if (!iface || !iface_match(iface,
                            &f->fw_in_if, f->fw_flg & IPV6_FW_F_OIFNAME))
                                continue;
                } else {
                        /* Check receive interface */
                        if ((f->fw_flg & IPV6_FW_F_IIFACE)
                            && (!rif || !iface_match(rif,
                              &f->fw_in_if, f->fw_flg & IPV6_FW_F_IIFNAME)))
                                continue;
                        /* Check outgoing interface */
                        if ((f->fw_flg & IPV6_FW_F_OIFACE)
                            && (!oif || !iface_match(oif,
                              &f->fw_out_if, f->fw_flg & IPV6_FW_F_OIFNAME)))
                                continue;
                }

                /* Check IP options */
                if (!ip6opts_match(&ip6, f, m, &off, &nxt, &offset))
                        continue;

                /* Fragments */
                if ((f->fw_flg & IPV6_FW_F_FRAG) && !offset)
                        continue;

                /* Check protocol; if wildcard, match */
                if (f->fw_prot == IPPROTO_IPV6)
                        goto got_match;

                /* If different, don't match */
                if (nxt != f->fw_prot)
                        continue;

#define PULLUP_TO(len)  do {                                            \
                            if ((*m)->m_len < (len)                     \
                                && (*m = m_pullup(*m, (len))) == NULL) {\
                                    goto dropit;                        \
                            }                                           \
                            *pip6 = ip6 = mtod(*m, struct ip6_hdr *);   \
                        } while (0)

                /* Protocol specific checks */
                switch (nxt) {
                case IPPROTO_TCP:
                    {
                        struct tcphdr *tcp6;

                        if (offset == 1) {      /* cf. RFC 1858 */
                                PULLUP_TO(off + 4); /* XXX ? */
                                goto bogusfrag;
                        }
                        if (offset != 0) {
                                /*
                                 * TCP flags and ports aren't available in this
                                 * packet -- if this rule specified either one,
                                 * we consider the rule a non-match.
                                 */
                                if (f->fw_nports != 0 ||
                                    f->fw_tcpf != f->fw_tcpnf)
                                        continue;

                                break;
                        }
                        PULLUP_TO(off + 14);
                        tcp6 = (struct tcphdr *) ((caddr_t)ip6 + off);
                        if (((f->fw_tcpf != f->fw_tcpnf) ||
                           (f->fw_ipflg & IPV6_FW_IF_TCPEST))  &&
                           !tcp6flg_match(tcp6, f))
                                continue;
                        src_port = ntohs(tcp6->th_sport);
                        dst_port = ntohs(tcp6->th_dport);
                        goto check_ports;
                    }

                case IPPROTO_UDP:
                    {
                        struct udphdr *udp;

                        if (offset != 0) {
                                /*
                                 * Port specification is unavailable -- if this
                                 * rule specifies a port, we consider the rule
                                 * a non-match.
                                 */
                                if (f->fw_nports != 0)
                                        continue;

                                break;
                        }
                        PULLUP_TO(off + 4);
                        udp = (struct udphdr *) ((caddr_t)ip6 + off);
                        src_port = ntohs(udp->uh_sport);
                        dst_port = ntohs(udp->uh_dport);
check_ports:
                        if (!port_match6(&f->fw_pts[0],
                            IPV6_FW_GETNSRCP(f), src_port,
                            f->fw_flg & IPV6_FW_F_SRNG))
                                continue;
                        if (!port_match6(&f->fw_pts[IPV6_FW_GETNSRCP(f)],
                            IPV6_FW_GETNDSTP(f), dst_port,
                            f->fw_flg & IPV6_FW_F_DRNG))
                                continue;
                        break;
                    }

                case IPPROTO_ICMPV6:
                    {
                        struct icmp6_hdr *icmp;

                        if (offset != 0)        /* Type isn't valid */
                                break;
                        PULLUP_TO(off + 2);
                        icmp = (struct icmp6_hdr *) ((caddr_t)ip6 + off);
                        if (!icmp6type_match(icmp, f))
                                continue;
                        break;
                    }
#undef PULLUP_TO

bogusfrag:
                        if (fw6_verbose)
                                ip6fw_report(NULL, ip6, rif, oif, off, nxt);
                        goto dropit;
                }

got_match:
#ifndef IP6FW_DIVERT_RESTART
                /* Ignore divert/tee rule if socket port is "ignport" */
                switch (f->fw_flg & IPV6_FW_F_COMMAND) {
                case IPV6_FW_F_DIVERT:
                case IPV6_FW_F_TEE:
                        if (f->fw_divert_port == ignport)
                                continue;       /* ignore this rule */
                        break;
                }

#endif /* IP6FW_DIVERT_RESTART */
                /* Update statistics */
                f->fw_pcnt += 1;
                f->fw_bcnt += ntohs(ip6->ip6_plen);
                f->timestamp = time_second;

                /* Log to console if desired */
                if ((f->fw_flg & IPV6_FW_F_PRN) && fw6_verbose)
                        ip6fw_report(f, ip6, rif, oif, off, nxt);

                /* Take appropriate action */
                switch (f->fw_flg & IPV6_FW_F_COMMAND) {
                case IPV6_FW_F_ACCEPT:
                        return(0);
                case IPV6_FW_F_COUNT:
                        continue;
                case IPV6_FW_F_DIVERT:
#ifdef IP6FW_DIVERT_RESTART
                        *cookie = f->fw_number;
#else
                        *cookie = htons(f->fw_divert_port);
#endif /* IP6FW_DIVERT_RESTART */
                        return(f->fw_divert_port);
                case IPV6_FW_F_TEE:
                        /*
                         * XXX someday tee packet here, but beware that you
                         * can't use m_copym() or m_copypacket() because
                         * the divert input routine modifies the mbuf
                         * (and these routines only increment reference
                         * counts in the case of mbuf clusters), so need
                         * to write custom routine.
                         */
                        continue;
                case IPV6_FW_F_SKIPTO:
#ifdef DIAGNOSTIC
                        while (chain->chain.le_next
                            && chain->chain.le_next->rule->fw_number
                                < f->fw_skipto_rule)
#else
                        while (chain->chain.le_next->rule->fw_number
                            < f->fw_skipto_rule)
#endif
                                chain = chain->chain.le_next;
                        continue;
                }

                /* Deny/reject this packet using this rule */
                rule = f;
                break;
        }

#ifdef DIAGNOSTIC
        /* Rule 65535 should always be there and should always match */
        if (!chain)
                panic("ip6_fw: chain");
#endif

        /*
         * At this point, we're going to drop the packet.
         * Send a reject notice if all of the following are true:
         *
         * - The packet matched a reject rule
         * - The packet is not an ICMP packet, or is an ICMP query packet
         * - The packet is not a multicast or broadcast packet
         */
        if ((rule->fw_flg & IPV6_FW_F_COMMAND) == IPV6_FW_F_REJECT
            && (nxt != IPPROTO_ICMPV6 || is_icmp6_query(ip6, off))
            && !((*m)->m_flags & (M_BCAST|M_MCAST))
            && !IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                switch (rule->fw_reject_code) {
                case IPV6_FW_REJECT_RST:
#if 1   /* not tested */
                  {
                        struct tcphdr *const tcp =
                                (struct tcphdr *) ((caddr_t)ip6 + off);
                        struct {
                                struct ip6_hdr ip6;
                                struct tcphdr th;
                        } ti;
                        tcp_seq ack, seq;
                        int flags;

                        if (offset != 0 || (tcp->th_flags & TH_RST))
                                break;

                        ti.ip6 = *ip6;
                        ti.th = *tcp;
                        ti.th.th_seq = ntohl(ti.th.th_seq);
                        ti.th.th_ack = ntohl(ti.th.th_ack);
                        ti.ip6.ip6_nxt = IPPROTO_TCP;
                        if (ti.th.th_flags & TH_ACK) {
                                ack = 0;
                                seq = ti.th.th_ack;
                                flags = TH_RST;
                        } else {
                                ack = ti.th.th_seq;
                                if (((*m)->m_flags & M_PKTHDR) != 0) {
                                        ack += (*m)->m_pkthdr.len - off
                                                - (ti.th.th_off << 2);
                                } else if (ip6->ip6_plen) {
                                        ack += ntohs(ip6->ip6_plen) + sizeof(*ip6)
                                                - off - (ti.th.th_off << 2);
                                } else {
                                        m_freem(*m);
                                        *m = NULL;
                                        break;
                                }
                                seq = 0;
                                flags = TH_RST|TH_ACK;
                        }
                        bcopy(&ti, ip6, sizeof(ti));
                        tcp_respond(NULL, ip6, (struct tcphdr *)(ip6 + 1),
                                *m, ack, seq, flags);
                        *m = NULL;
                        break;
                  }
#endif
                default:        /* Send an ICMP unreachable using code */
                        if (oif)
                                (*m)->m_pkthdr.rcvif = oif;
                        icmp6_error(*m, ICMP6_DST_UNREACH,
                            rule->fw_reject_code, 0);
                        *m = NULL;
                        break;
                }
        }

dropit:
        /*
         * Finally, drop the packet.
         */
        if (*m) {
                m_freem(*m);
                *m = NULL;
        }
        return(0);
}

static int
add_entry6(struct ip6_fw_head *chainptr, struct ip6_fw *frwl)
{
        struct ip6_fw *ftmp = NULL;
        struct ip6_fw_chain *fwc = NULL, *fcp, *fcpl = NULL;
        u_short nbr = 0;

        fwc = kmalloc(sizeof *fwc, M_IP6FW, M_INTWAIT);
        ftmp = kmalloc(sizeof *ftmp, M_IP6FW, M_INTWAIT);

        bcopy(frwl, ftmp, sizeof(struct ip6_fw));
        ftmp->fw_in_if.fu_via_if.name[IP6FW_IFNLEN - 1] = '\0';
        ftmp->fw_pcnt = 0L;
        ftmp->fw_bcnt = 0L;
        fwc->rule = ftmp;

        crit_enter();

        if (!chainptr->lh_first) {
                LIST_INSERT_HEAD(chainptr, fwc, chain);
                crit_exit();
                return(0);
        } else if (ftmp->fw_number == (u_short)-1) {
                if (fwc)  kfree(fwc, M_IP6FW);
                if (ftmp) kfree(ftmp, M_IP6FW);
                crit_exit();
                dprintf(("%s bad rule number\n", err_prefix));
                return (EINVAL);
        }

        /* If entry number is 0, find highest numbered rule and add 100 */
        if (ftmp->fw_number == 0) {
                LIST_FOREACH(fcp, chainptr, chain) {
                        if (fcp->rule->fw_number != (u_short)-1)
                                nbr = fcp->rule->fw_number;
                        else
                                break;
                }
                if (nbr < (u_short)-1 - 100)
                        nbr += 100;
                ftmp->fw_number = nbr;
        }

        /* Got a valid number; now insert it, keeping the list ordered */
        LIST_FOREACH(fcp, chainptr, chain) {
                if (fcp->rule->fw_number > ftmp->fw_number) {
                        if (fcpl) {
                                LIST_INSERT_AFTER(fcpl, fwc, chain);
                        } else {
                                LIST_INSERT_HEAD(chainptr, fwc, chain);
                        }
                        break;
                } else {
                        fcpl = fcp;
                }
        }

        crit_exit();
        return (0);
}

static int
del_entry6(struct ip6_fw_head *chainptr, u_short number)
{
        struct ip6_fw_chain *fcp;

        crit_enter();

        fcp = chainptr->lh_first;
        if (number != (u_short)-1) {
                for (; fcp; fcp = fcp->chain.le_next) {
                        if (fcp->rule->fw_number == number) {
                                LIST_REMOVE(fcp, chain);
                                crit_exit();
                                kfree(fcp->rule, M_IP6FW);
                                kfree(fcp, M_IP6FW);
                                return 0;
                        }
                }
        }

        crit_exit();
        return (EINVAL);
}

static int
zero_entry6(struct mbuf *m)
{
        struct ip6_fw *frwl;
        struct ip6_fw_chain *fcp;

        if (m && m->m_len != 0) {
                if (m->m_len != sizeof(struct ip6_fw))
                        return(EINVAL);
                frwl = mtod(m, struct ip6_fw *);
        }
        else
                frwl = NULL;

        /*
         *      It's possible to insert multiple chain entries with the
         *      same number, so we don't stop after finding the first
         *      match if zeroing a specific entry.
         */
        crit_enter();
        for (fcp = ip6_fw_chain.lh_first; fcp; fcp = fcp->chain.le_next)
                if (!frwl || frwl->fw_number == fcp->rule->fw_number) {
                        fcp->rule->fw_bcnt = fcp->rule->fw_pcnt = 0;
                        fcp->rule->timestamp = 0;
                }
        crit_exit();

        if (fw6_verbose) {
                if (frwl)
                        log(LOG_SECURITY | LOG_NOTICE,
                            "ip6fw: Entry %d cleared.\n", frwl->fw_number);
                else
                        log(LOG_SECURITY | LOG_NOTICE,
                            "ip6fw: Accounting cleared.\n");
        }

        return(0);
}

static struct ip6_fw *
check_ip6fw_mbuf(struct mbuf *m)
{
        /* Check length */
        if (m->m_len != sizeof(struct ip6_fw)) {
                dprintf(("%s len=%d, want %d\n", err_prefix, m->m_len,
                        (int)sizeof(struct ip6_fw)));
                return (NULL);
        }
        return(check_ip6fw_struct(mtod(m, struct ip6_fw *)));
}

static struct ip6_fw *
check_ip6fw_struct(struct ip6_fw *frwl)
{
        /* Check for invalid flag bits */
        if ((frwl->fw_flg & ~IPV6_FW_F_MASK) != 0) {
                dprintf(("%s undefined flag bits set (flags=%x)\n",
                    err_prefix, frwl->fw_flg));
                return (NULL);
        }
        /* Must apply to incoming or outgoing (or both) */
        if (!(frwl->fw_flg & (IPV6_FW_F_IN | IPV6_FW_F_OUT))) {
                dprintf(("%s neither in nor out\n", err_prefix));
                return (NULL);
        }
        /* Empty interface name is no good */
        if (((frwl->fw_flg & IPV6_FW_F_IIFNAME)
              && !*frwl->fw_in_if.fu_via_if.name)
            || ((frwl->fw_flg & IPV6_FW_F_OIFNAME)
              && !*frwl->fw_out_if.fu_via_if.name)) {
                dprintf(("%s empty interface name\n", err_prefix));
                return (NULL);
        }
        /* Sanity check interface matching */
        if ((frwl->fw_flg & IF6_FW_F_VIAHACK) == IF6_FW_F_VIAHACK) {
                ;               /* allow "via" backwards compatibility */
        } else if ((frwl->fw_flg & IPV6_FW_F_IN)
            && (frwl->fw_flg & IPV6_FW_F_OIFACE)) {
                dprintf(("%s outgoing interface check on incoming\n",
                    err_prefix));
                return (NULL);
        }
        /* Sanity check port ranges */
        if ((frwl->fw_flg & IPV6_FW_F_SRNG) && IPV6_FW_GETNSRCP(frwl) < 2) {
                dprintf(("%s src range set but n_src_p=%d\n",
                    err_prefix, IPV6_FW_GETNSRCP(frwl)));
                return (NULL);
        }
        if ((frwl->fw_flg & IPV6_FW_F_DRNG) && IPV6_FW_GETNDSTP(frwl) < 2) {
                dprintf(("%s dst range set but n_dst_p=%d\n",
                    err_prefix, IPV6_FW_GETNDSTP(frwl)));
                return (NULL);
        }
        if (IPV6_FW_GETNSRCP(frwl) + IPV6_FW_GETNDSTP(frwl) > IPV6_FW_MAX_PORTS) {
                dprintf(("%s too many ports (%d+%d)\n",
                    err_prefix, IPV6_FW_GETNSRCP(frwl), IPV6_FW_GETNDSTP(frwl)));
                return (NULL);
        }
        /*
         *      Protocols other than TCP/UDP don't use port range
         */
        if ((frwl->fw_prot != IPPROTO_TCP) &&
            (frwl->fw_prot != IPPROTO_UDP) &&
            (IPV6_FW_GETNSRCP(frwl) || IPV6_FW_GETNDSTP(frwl))) {
                dprintf(("%s port(s) specified for non TCP/UDP rule\n",
                    err_prefix));
                return(NULL);
        }

        /*
         *      Rather than modify the entry to make such entries work,
         *      we reject this rule and require user level utilities
         *      to enforce whatever policy they deem appropriate.
         */
        if ((frwl->fw_src.s6_addr32[0] & (~frwl->fw_smsk.s6_addr32[0])) ||
                (frwl->fw_src.s6_addr32[1] & (~frwl->fw_smsk.s6_addr32[1])) ||
                (frwl->fw_src.s6_addr32[2] & (~frwl->fw_smsk.s6_addr32[2])) ||
                (frwl->fw_src.s6_addr32[3] & (~frwl->fw_smsk.s6_addr32[3])) ||
                (frwl->fw_dst.s6_addr32[0] & (~frwl->fw_dmsk.s6_addr32[0])) ||
                (frwl->fw_dst.s6_addr32[1] & (~frwl->fw_dmsk.s6_addr32[1])) ||
                (frwl->fw_dst.s6_addr32[2] & (~frwl->fw_dmsk.s6_addr32[2])) ||
                (frwl->fw_dst.s6_addr32[3] & (~frwl->fw_dmsk.s6_addr32[3]))) {
                dprintf(("%s rule never matches\n", err_prefix));
                return(NULL);
        }

        if ((frwl->fw_flg & IPV6_FW_F_FRAG) &&
                (frwl->fw_prot == IPPROTO_UDP || frwl->fw_prot == IPPROTO_TCP)) {
                if (frwl->fw_nports) {
                        dprintf(("%s cannot mix 'frag' and ports\n", err_prefix));
                        return(NULL);
                }
                if (frwl->fw_prot == IPPROTO_TCP &&
                        frwl->fw_tcpf != frwl->fw_tcpnf) {
                        dprintf(("%s cannot mix 'frag' with TCP flags\n", err_prefix));
                        return(NULL);
                }
        }

        /* Check command specific stuff */
        switch (frwl->fw_flg & IPV6_FW_F_COMMAND)
        {
        case IPV6_FW_F_REJECT:
                if (frwl->fw_reject_code >= 0x100
                    && !(frwl->fw_prot == IPPROTO_TCP
                      && frwl->fw_reject_code == IPV6_FW_REJECT_RST)) {
                        dprintf(("%s unknown reject code\n", err_prefix));
                        return(NULL);
                }
                break;
        case IPV6_FW_F_DIVERT:          /* Diverting to port zero is invalid */
        case IPV6_FW_F_TEE:
                if (frwl->fw_divert_port == 0) {
                        dprintf(("%s can't divert to port 0\n", err_prefix));
                        return (NULL);
                }
                break;
        case IPV6_FW_F_DENY:
        case IPV6_FW_F_ACCEPT:
        case IPV6_FW_F_COUNT:
        case IPV6_FW_F_SKIPTO:
                break;
        default:
                dprintf(("%s invalid command\n", err_prefix));
                return(NULL);
        }

        return frwl;
}

static int
ip6_fw_ctl(int stage, struct mbuf **mm)
{
        int error;
        struct mbuf *m;

        if (stage == IPV6_FW_GET) {
                struct ip6_fw_chain *fcp = ip6_fw_chain.lh_first;
                *mm = m = m_get(M_WAITOK, MT_DATA); /* XXX */
                if (sizeof *(fcp->rule) > MLEN)
                        MCLGET(m, M_WAITOK);
                for (; fcp; fcp = fcp->chain.le_next) {
                        bcopy(fcp->rule, m->m_data, sizeof *(fcp->rule));
                        m->m_len = sizeof *(fcp->rule);
                        m->m_next = m_get(M_WAITOK, MT_DATA); /* XXX */
                        m = m->m_next;
                        if (sizeof *(fcp->rule) > MLEN)
                                MCLGET(m, M_WAITOK);
                        m->m_len = 0;
                }
                return (0);
        }
        m = *mm;
        /* only allow get calls if secure mode > 2 */
        if (securelevel > 2) {
                if (m) {
                        m_freem(m);
                        *mm = NULL;
                }
                return(EPERM);
        }
        if (stage == IPV6_FW_FLUSH) {
                while (ip6_fw_chain.lh_first != NULL &&
                    ip6_fw_chain.lh_first->rule->fw_number != (u_short)-1) {
                        struct ip6_fw_chain *fcp = ip6_fw_chain.lh_first;
                        crit_enter();
                        LIST_REMOVE(ip6_fw_chain.lh_first, chain);
                        crit_exit();
                        kfree(fcp->rule, M_IP6FW);
                        kfree(fcp, M_IP6FW);
                }
                if (m) {
                        m_freem(m);
                        *mm = NULL;
                }
                return (0);
        }
        if (stage == IPV6_FW_ZERO) {
                error = zero_entry6(m);
                if (m) {
                        m_freem(m);
                        *mm = NULL;
                }
                return (error);
        }
        if (m == NULL) {
                kprintf("%s NULL mbuf ptr\n", err_prefix);
                return (EINVAL);
        }

        if (stage == IPV6_FW_ADD) {
                struct ip6_fw *frwl = check_ip6fw_mbuf(m);

                if (!frwl)
                        error = EINVAL;
                else
                        error = add_entry6(&ip6_fw_chain, frwl);
                if (m) {
                        m_freem(m);
                        *mm = NULL;
                }
                return error;
        }
        if (stage == IPV6_FW_DEL) {
                if (m->m_len != sizeof(struct ip6_fw)) {
                        dprintf(("%s len=%d, want %d\n", err_prefix, m->m_len,
                                (int)sizeof(struct ip6_fw)));
                        error = EINVAL;
                } else if (mtod(m, struct ip6_fw *)->fw_number == (u_short)-1) {
                        dprintf(("%s can't delete rule 65535\n", err_prefix));
                        error = EINVAL;
                } else
                        error = del_entry6(&ip6_fw_chain,
                            mtod(m, struct ip6_fw *)->fw_number);
                if (m) {
                        m_freem(m);
                        *mm = NULL;
                }
                return error;
        }

        dprintf(("%s unknown request %d\n", err_prefix, stage));
        if (m) {
                m_freem(m);
                *mm = NULL;
        }
        return (EINVAL);
}

void
ip6_fw_init(void)
{
        struct ip6_fw default_rule;

        ip6_fw_chk_ptr = ip6_fw_chk;
        ip6_fw_ctl_ptr = ip6_fw_ctl;
        LIST_INIT(&ip6_fw_chain);

        bzero(&default_rule, sizeof default_rule);
        default_rule.fw_prot = IPPROTO_IPV6;
        default_rule.fw_number = (u_short)-1;
#ifdef IPV6FIREWALL_DEFAULT_TO_ACCEPT
        default_rule.fw_flg |= IPV6_FW_F_ACCEPT;
#else
        default_rule.fw_flg |= IPV6_FW_F_DENY;
#endif
        default_rule.fw_flg |= IPV6_FW_F_IN | IPV6_FW_F_OUT;
        if (check_ip6fw_struct(&default_rule) == NULL ||
                add_entry6(&ip6_fw_chain, &default_rule))
                panic(__func__);

        kprintf("IPv6 packet filtering initialized, ");
#ifdef IPV6FIREWALL_DEFAULT_TO_ACCEPT
        kprintf("default to accept, ");
#endif
#ifndef IPV6FIREWALL_VERBOSE
        kprintf("logging disabled\n");
#else
        if (fw6_verbose_limit == 0)
                kprintf("unlimited logging\n");
        else
                kprintf("logging limited to %d packets/entry\n",
                    fw6_verbose_limit);
#endif
}

static ip6_fw_chk_t *old_chk_ptr;
static ip6_fw_ctl_t *old_ctl_ptr;

static int
ip6fw_modevent(module_t mod, int type, void *unused)
{
        switch (type) {
        case MOD_LOAD:
                crit_enter();

                old_chk_ptr = ip6_fw_chk_ptr;
                old_ctl_ptr = ip6_fw_ctl_ptr;

                ip6_fw_init();
                crit_exit();
                return 0;
        case MOD_UNLOAD:
                crit_enter();
                ip6_fw_chk_ptr =  old_chk_ptr;
                ip6_fw_ctl_ptr =  old_ctl_ptr;
                while (LIST_FIRST(&ip6_fw_chain) != NULL) {
                        struct ip6_fw_chain *fcp = LIST_FIRST(&ip6_fw_chain);
                        LIST_REMOVE(LIST_FIRST(&ip6_fw_chain), chain);
                        kfree(fcp->rule, M_IP6FW);
                        kfree(fcp, M_IP6FW);
                }

                crit_exit();
                kprintf("IPv6 firewall unloaded\n");
                return 0;
        default:
                break;
        }
        return 0;
}

static moduledata_t ip6fwmod = {
        "ip6fw",
        ip6fw_modevent,
        0
};
DECLARE_MODULE(ip6fw, ip6fwmod, SI_SUB_PSEUDO, SI_ORDER_ANY);