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[freebsd/src.git] / sys / netinet / ip_divert.c

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1988, 1993
 *      The Regents of the University of California.  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 University 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 REGENTS 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 REGENTS 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.
 */

#include <sys/cdefs.h>
#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_sctp.h"

#include <sys/param.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/kernel.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <net/vnet.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/netisr.h>

#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_divert.h>
#ifdef INET6
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#endif
#if defined(SCTP) || defined(SCTP_SUPPORT)
#include <netinet/sctp_crc32.h>
#endif

#include <security/mac/mac_framework.h>
/*
 * Divert sockets
 */

/*
 * Allocate enough space to hold a full IP packet
 */
#define DIVSNDQ         (65536 + 100)
#define DIVRCVQ         (65536 + 100)

/*
 * Usually a system has very few divert ports.  Previous implementation
 * used a linked list.
 */
#define DIVHASHSIZE     (1 << 3)        /* 8 entries, one cache line. */
#define DIVHASH(port)   (port % DIVHASHSIZE)
#define DCBHASH(dcb)    ((dcb)->dcb_port % DIVHASHSIZE)

/*
 * Divert sockets work in conjunction with ipfw or other packet filters,
 * see the divert(4) manpage for features.
 * Packets are selected by the packet filter and tagged with an
 * MTAG_IPFW_RULE tag carrying the 'divert port' number (as set by
 * the packet filter) and information on the matching filter rule for
 * subsequent reinjection. The divert_port is used to put the packet
 * on the corresponding divert socket, while the rule number is passed
 * up (at least partially) as the sin_port in the struct sockaddr.
 *
 * Packets written to the divert socket carry in sin_addr a
 * destination address, and in sin_port the number of the filter rule
 * after which to continue processing.
 * If the destination address is INADDR_ANY, the packet is treated as
 * as outgoing and sent to ip_output(); otherwise it is treated as
 * incoming and sent to ip_input().
 * Further, sin_zero carries some information on the interface,
 * which can be used in the reinject -- see comments in the code.
 *
 * On reinjection, processing in ip_input() and ip_output()
 * will be exactly the same as for the original packet, except that
 * packet filter processing will start at the rule number after the one
 * written in the sin_port (ipfw does not allow a rule #0, so sin_port=0
 * will apply the entire ruleset to the packet).
 */
static SYSCTL_NODE(_net_inet, OID_AUTO, divert, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "divert(4)");

VNET_PCPUSTAT_DEFINE_STATIC(struct divstat, divstat);
VNET_PCPUSTAT_SYSINIT(divstat);
#ifdef VIMAGE
VNET_PCPUSTAT_SYSUNINIT(divstat);
#endif
SYSCTL_VNET_PCPUSTAT(_net_inet_divert, OID_AUTO, stats, struct divstat,
    divstat, "divert(4) socket statistics");
#define DIVSTAT_INC(name)       \
    VNET_PCPUSTAT_ADD(struct divstat, divstat, div_ ## name, 1)

static u_long   div_sendspace = DIVSNDQ;        /* XXX sysctl ? */
static u_long   div_recvspace = DIVRCVQ;        /* XXX sysctl ? */

static int div_output_inbound(int fmaily, struct socket *so, struct mbuf *m,
    struct sockaddr_in *sin);
static int div_output_outbound(int family, struct socket *so, struct mbuf *m);

struct divcb {
        union {
                SLIST_ENTRY(divcb)      dcb_next;
                intptr_t                dcb_bound;
#define DCB_UNBOUND     ((intptr_t)-1)
        };
        struct socket           *dcb_socket;
        uint16_t                 dcb_port;
        uint64_t                 dcb_gencnt;
        struct epoch_context     dcb_epochctx;
};

SLIST_HEAD(divhashhead, divcb);

VNET_DEFINE_STATIC(struct divhashhead, divhash[DIVHASHSIZE]) = {};
#define V_divhash       VNET(divhash)
VNET_DEFINE_STATIC(uint64_t, dcb_count) = 0;
#define V_dcb_count     VNET(dcb_count)
VNET_DEFINE_STATIC(uint64_t, dcb_gencnt) = 0;
#define V_dcb_gencnt    VNET(dcb_gencnt)

static struct mtx divert_mtx;
MTX_SYSINIT(divert, &divert_mtx, "divert(4) socket pcb lists", MTX_DEF);
#define DIVERT_LOCK()   mtx_lock(&divert_mtx)
#define DIVERT_UNLOCK() mtx_unlock(&divert_mtx)

/*
 * Divert a packet by passing it up to the divert socket at port 'port'.
 */
static void
divert_packet(struct mbuf *m, bool incoming)
{
        struct divcb *dcb;
        u_int16_t nport;
        struct sockaddr_in divsrc;
        struct m_tag *mtag;
        uint16_t cookie;

        NET_EPOCH_ASSERT();

        mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
        if (mtag != NULL) {
                cookie = ((struct ipfw_rule_ref *)(mtag+1))->rulenum;
                nport = htons((uint16_t)
                    (((struct ipfw_rule_ref *)(mtag+1))->info));
        } else if ((mtag = m_tag_locate(m, MTAG_PF_DIVERT, 0, NULL)) != NULL) {
                cookie = ((struct pf_divert_mtag *)(mtag+1))->idir;
                nport = htons(((struct pf_divert_mtag *)(mtag+1))->port);
        } else {
                m_freem(m);
                return;
        }
        /* Assure header */
        if (m->m_len < sizeof(struct ip) &&
            (m = m_pullup(m, sizeof(struct ip))) == NULL)
                return;
#ifdef INET
        /* Delayed checksums are currently not compatible with divert. */
        if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
                in_delayed_cksum(m);
                m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
        }
#if defined(SCTP) || defined(SCTP_SUPPORT)
        if (m->m_pkthdr.csum_flags & CSUM_SCTP) {
                struct ip *ip;

                ip = mtod(m, struct ip *);
                sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
                m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
        }
#endif
#endif
#ifdef INET6
        if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
                in6_delayed_cksum(m, m->m_pkthdr.len -
                    sizeof(struct ip6_hdr), sizeof(struct ip6_hdr));
                m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
        }
#if defined(SCTP) || defined(SCTP_SUPPORT)
        if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
                sctp_delayed_cksum(m, sizeof(struct ip6_hdr));
                m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
        }
#endif
#endif /* INET6 */
        bzero(&divsrc, sizeof(divsrc));
        divsrc.sin_len = sizeof(divsrc);
        divsrc.sin_family = AF_INET;
        /* record matching rule, in host format */
        divsrc.sin_port = cookie;
        /*
         * Record receive interface address, if any.
         * But only for incoming packets.
         */
        if (incoming) {
                struct ifaddr *ifa;
                struct ifnet *ifp;

                /* Sanity check */
                M_ASSERTPKTHDR(m);

                /* Find IP address for receive interface */
                ifp = m->m_pkthdr.rcvif;
                CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                        if (ifa->ifa_addr->sa_family != AF_INET)
                                continue;
                        divsrc.sin_addr =
                            ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
                        break;
                }
        }
        /*
         * Record the incoming interface name whenever we have one.
         */
        if (m->m_pkthdr.rcvif) {
                /*
                 * Hide the actual interface name in there in the
                 * sin_zero array. XXX This needs to be moved to a
                 * different sockaddr type for divert, e.g.
                 * sockaddr_div with multiple fields like
                 * sockaddr_dl. Presently we have only 7 bytes
                 * but that will do for now as most interfaces
                 * are 4 or less + 2 or less bytes for unit.
                 * There is probably a faster way of doing this,
                 * possibly taking it from the sockaddr_dl on the iface.
                 * This solves the problem of a P2P link and a LAN interface
                 * having the same address, which can result in the wrong
                 * interface being assigned to the packet when fed back
                 * into the divert socket. Theoretically if the daemon saves
                 * and re-uses the sockaddr_in as suggested in the man pages,
                 * this iface name will come along for the ride.
                 * (see div_output for the other half of this.)
                 */
                strlcpy(divsrc.sin_zero, m->m_pkthdr.rcvif->if_xname,
                    sizeof(divsrc.sin_zero));
        }

        /* Put packet on socket queue, if any */
        SLIST_FOREACH(dcb, &V_divhash[DIVHASH(nport)], dcb_next)
                if (dcb->dcb_port == nport)
                        break;

        if (dcb != NULL) {
                struct socket *sa = dcb->dcb_socket;

                SOCKBUF_LOCK(&sa->so_rcv);
                if (sbappendaddr_locked(&sa->so_rcv,
                    (struct sockaddr *)&divsrc, m, NULL) == 0) {
                        soroverflow_locked(sa);
                        m_freem(m);
                } else {
                        sorwakeup_locked(sa);
                        DIVSTAT_INC(diverted);
                }
        } else {
                DIVSTAT_INC(noport);
                m_freem(m);
        }
}

/*
 * Deliver packet back into the IP processing machinery.
 *
 * If no address specified, or address is 0.0.0.0, send to ip_output();
 * otherwise, send to ip_input() and mark as having been received on
 * the interface with that address.
 */
static int
div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
    struct mbuf *control, struct thread *td)
{
        struct epoch_tracker et;
        struct sockaddr_in *sin = (struct sockaddr_in *)nam;
        const struct ip *ip;
        struct m_tag *mtag;
        struct ipfw_rule_ref *dt;
        struct pf_divert_mtag *pfdt;
        int error, family;

        if (control)
                m_freem(control);

        /* Packet must have a header (but that's about it) */
        if (m->m_len < sizeof (struct ip) &&
            (m = m_pullup(m, sizeof (struct ip))) == NULL) {
                m_freem(m);
                return (EINVAL);
        }

        if (sin != NULL) {
                if (sin->sin_family != AF_INET) {
                        m_freem(m);
                        return (EAFNOSUPPORT);
                }
                if (sin->sin_len != sizeof(*sin)) {
                        m_freem(m);
                        return (EINVAL);
                }
        }

        /*
         * An mbuf may hasn't come from userland, but we pretend
         * that it has.
         */
        m->m_pkthdr.rcvif = NULL;
        m->m_nextpkt = NULL;
        M_SETFIB(m, so->so_fibnum);

        mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
        if (mtag == NULL) {
                /* this should be normal */
                mtag = m_tag_alloc(MTAG_IPFW_RULE, 0,
                    sizeof(struct ipfw_rule_ref), M_NOWAIT | M_ZERO);
                if (mtag == NULL) {
                        m_freem(m);
                        return (ENOBUFS);
                }
                m_tag_prepend(m, mtag);
        }
        dt = (struct ipfw_rule_ref *)(mtag+1);

        /* Loopback avoidance and state recovery */
        if (sin) {
                int i;

                /* set the starting point. We provide a non-zero slot,
                 * but a non_matching chain_id to skip that info and use
                 * the rulenum/rule_id.
                 */
                dt->slot = 1; /* dummy, chain_id is invalid */
                dt->chain_id = 0;
                dt->rulenum = sin->sin_port+1; /* host format ? */
                dt->rule_id = 0;
                /* XXX: broken for IPv6 */
                /*
                 * Find receive interface with the given name, stuffed
                 * (if it exists) in the sin_zero[] field.
                 * The name is user supplied data so don't trust its size
                 * or that it is zero terminated.
                 */
                for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
                        ;
                if ( i > 0 && i < sizeof(sin->sin_zero))
                        m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
        }

        ip = mtod(m, struct ip *);
        switch (ip->ip_v) {
#ifdef INET
        case IPVERSION:
                family = AF_INET;
                break;
#endif
#ifdef INET6
        case IPV6_VERSION >> 4:
                family = AF_INET6;
                break;
#endif
        default:
                m_freem(m);
                return (EAFNOSUPPORT);
        }

        mtag = m_tag_locate(m, MTAG_PF_DIVERT, 0, NULL);
        if (mtag == NULL) {
                /* this should be normal */
                mtag = m_tag_alloc(MTAG_PF_DIVERT, 0,
                    sizeof(struct pf_divert_mtag), M_NOWAIT | M_ZERO);
                if (mtag == NULL) {
                        m_freem(m);
                        return (ENOBUFS);
                }
                m_tag_prepend(m, mtag);
        }
        pfdt = (struct pf_divert_mtag *)(mtag+1);
        if (sin)
                pfdt->idir = sin->sin_port;

        /* Reinject packet into the system as incoming or outgoing */
        NET_EPOCH_ENTER(et);
        if (!sin || sin->sin_addr.s_addr == 0) {
                dt->info |= IPFW_IS_DIVERT | IPFW_INFO_OUT;
                pfdt->ndir = PF_DIVERT_MTAG_DIR_OUT;
                error = div_output_outbound(family, so, m);
        } else {
                dt->info |= IPFW_IS_DIVERT | IPFW_INFO_IN;
                pfdt->ndir = PF_DIVERT_MTAG_DIR_IN;
                error = div_output_inbound(family, so, m, sin);
        }
        NET_EPOCH_EXIT(et);

        return (error);
}

/*
 * Sends mbuf @m to the wire via ip[6]_output().
 *
 * Returns 0 on success or an errno value on failure.  @m is always consumed.
 */
static int
div_output_outbound(int family, struct socket *so, struct mbuf *m)
{
        int error;

        switch (family) {
#ifdef INET
        case AF_INET:
            {
                struct ip *const ip = mtod(m, struct ip *);

                /* Don't allow packet length sizes that will crash. */
                if (((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
                        m_freem(m);
                        return (EINVAL);
                }
                break;
            }
#endif
#ifdef INET6
        case AF_INET6:
            {
                struct ip6_hdr *const ip6 = mtod(m, struct ip6_hdr *);

                /* Don't allow packet length sizes that will crash */
                if (((u_short)ntohs(ip6->ip6_plen) > m->m_pkthdr.len)) {
                        m_freem(m);
                        return (EINVAL);
                }
                break;
            }
#endif
        }

#ifdef MAC
        mac_socket_create_mbuf(so, m);
#endif

        error = 0;
        switch (family) {
#ifdef INET
        case AF_INET:
                error = ip_output(m, NULL, NULL,
                    ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0)
                    | IP_ALLOWBROADCAST | IP_RAWOUTPUT, NULL, NULL);
                break;
#endif
#ifdef INET6
        case AF_INET6:
                error = ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
                break;
#endif
        }
        if (error == 0)
                DIVSTAT_INC(outbound);

        return (error);
}

/*
 * Schedules mbuf @m for local processing via IPv4/IPv6 netisr queue.
 *
 * Returns 0 on success or an errno value on failure.  @m is always consumed.
 */
static int
div_output_inbound(int family, struct socket *so, struct mbuf *m,
    struct sockaddr_in *sin)
{
        struct ifaddr *ifa;

        if (m->m_pkthdr.rcvif == NULL) {
                /*
                 * No luck with the name, check by IP address.
                 * Clear the port and the ifname to make sure
                 * there are no distractions for ifa_ifwithaddr.
                 */

                /* XXX: broken for IPv6 */
                bzero(sin->sin_zero, sizeof(sin->sin_zero));
                sin->sin_port = 0;
                ifa = ifa_ifwithaddr((struct sockaddr *) sin);
                if (ifa == NULL) {
                        m_freem(m);
                        return (EADDRNOTAVAIL);
                }
                m->m_pkthdr.rcvif = ifa->ifa_ifp;
        }
#ifdef MAC
        mac_socket_create_mbuf(so, m);
#endif
        /* Send packet to input processing via netisr */
        switch (family) {
#ifdef INET
        case AF_INET:
            {
                const struct ip *ip;

                ip = mtod(m, struct ip *);
                /*
                 * Restore M_BCAST flag when destination address is
                 * broadcast. It is expected by ip_tryforward().
                 */
                if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)))
                        m->m_flags |= M_MCAST;
                else if (in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
                        m->m_flags |= M_BCAST;
                netisr_queue_src(NETISR_IP, (uintptr_t)so, m);
                DIVSTAT_INC(inbound);
                break;
            }
#endif
#ifdef INET6
        case AF_INET6:
                netisr_queue_src(NETISR_IPV6, (uintptr_t)so, m);
                DIVSTAT_INC(inbound);
                break;
#endif
        default:
                m_freem(m);
                return (EINVAL);
        }

        return (0);
}

static int
div_attach(struct socket *so, int proto, struct thread *td)
{
        struct divcb *dcb;
        int error;

        if (td != NULL) {
                error = priv_check(td, PRIV_NETINET_DIVERT);
                if (error)
                        return (error);
        }
        error = soreserve(so, div_sendspace, div_recvspace);
        if (error)
                return error;
        dcb = malloc(sizeof(*dcb), M_PCB, M_WAITOK);
        dcb->dcb_bound = DCB_UNBOUND;
        dcb->dcb_socket = so;
        DIVERT_LOCK();
        V_dcb_count++;
        dcb->dcb_gencnt = ++V_dcb_gencnt;
        DIVERT_UNLOCK();
        so->so_pcb = dcb;

        return (0);
}

static void
div_free(epoch_context_t ctx)
{
        struct divcb *dcb = __containerof(ctx, struct divcb, dcb_epochctx);

        free(dcb, M_PCB);
}

static void
div_detach(struct socket *so)
{
        struct divcb *dcb = so->so_pcb;

        so->so_pcb = NULL;
        DIVERT_LOCK();
        if (dcb->dcb_bound != DCB_UNBOUND)
                SLIST_REMOVE(&V_divhash[DCBHASH(dcb)], dcb, divcb, dcb_next);
        V_dcb_count--;
        V_dcb_gencnt++;
        DIVERT_UNLOCK();
        NET_EPOCH_CALL(div_free, &dcb->dcb_epochctx);
}

static int
div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
{
        struct divcb *dcb;
        uint16_t port;

        if (nam->sa_family != AF_INET)
                return EAFNOSUPPORT;
        if (nam->sa_len != sizeof(struct sockaddr_in))
                return EINVAL;
        port = ((struct sockaddr_in *)nam)->sin_port;
        DIVERT_LOCK();
        SLIST_FOREACH(dcb, &V_divhash[DIVHASH(port)], dcb_next)
                if (dcb->dcb_port == port) {
                        DIVERT_UNLOCK();
                        return (EADDRINUSE);
                }
        dcb = so->so_pcb;
        if (dcb->dcb_bound != DCB_UNBOUND)
                SLIST_REMOVE(&V_divhash[DCBHASH(dcb)], dcb, divcb, dcb_next);
        dcb->dcb_port = port;
        SLIST_INSERT_HEAD(&V_divhash[DIVHASH(port)], dcb, dcb_next);
        DIVERT_UNLOCK();

        return (0);
}

static int
div_pcblist(SYSCTL_HANDLER_ARGS)
{
        struct xinpgen xig;
        struct divcb *dcb;
        int error;

        if (req->newptr != 0)
                return EPERM;

        if (req->oldptr == 0) {
                u_int n;

                n = V_dcb_count;
                n += imax(n / 8, 10);
                req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xinpcb);
                return 0;
        }

        if ((error = sysctl_wire_old_buffer(req, 0)) != 0)
                return (error);

        bzero(&xig, sizeof(xig));
        xig.xig_len = sizeof xig;
        xig.xig_count = V_dcb_count;
        xig.xig_gen = V_dcb_gencnt;
        xig.xig_sogen = so_gencnt;
        error = SYSCTL_OUT(req, &xig, sizeof xig);
        if (error)
                return error;

        DIVERT_LOCK();
        for (int i = 0; i < DIVHASHSIZE; i++)
                SLIST_FOREACH(dcb, &V_divhash[i], dcb_next) {
                        if (dcb->dcb_gencnt <= xig.xig_gen) {
                                struct xinpcb xi;

                                bzero(&xi, sizeof(xi));
                                xi.xi_len = sizeof(struct xinpcb);
                                sotoxsocket(dcb->dcb_socket, &xi.xi_socket);
                                xi.inp_gencnt = dcb->dcb_gencnt;
                                xi.inp_vflag = INP_IPV4; /* XXX: netstat(1) */
                                xi.inp_inc.inc_ie.ie_lport = dcb->dcb_port;
                                error = SYSCTL_OUT(req, &xi, sizeof xi);
                                if (error)
                                        goto errout;
                        }
                }

        /*
         * Give the user an updated idea of our state.
         * If the generation differs from what we told
         * her before, she knows that something happened
         * while we were processing this request, and it
         * might be necessary to retry.
         */
        xig.xig_gen = V_dcb_gencnt;
        xig.xig_sogen = so_gencnt;
        xig.xig_count = V_dcb_count;
        error = SYSCTL_OUT(req, &xig, sizeof xig);

errout:
        DIVERT_UNLOCK();

        return (error);
}
SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist,
    CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, div_pcblist,
    "S,xinpcb", "List of active divert sockets");

static struct protosw div_protosw = {
        .pr_type =              SOCK_RAW,
        .pr_flags =             PR_ATOMIC|PR_ADDR,
        .pr_attach =            div_attach,
        .pr_bind =              div_bind,
        .pr_detach =            div_detach,
        .pr_send =              div_send,
};

static struct domain divertdomain = {
        .dom_family =   PF_DIVERT,
        .dom_name =     "divert",
        .dom_nprotosw = 1,
        .dom_protosw =  { &div_protosw },
};

static int
div_modevent(module_t mod, int type, void *unused)
{
        int err = 0;

        switch (type) {
        case MOD_LOAD:
                domain_add(&divertdomain);
                ip_divert_ptr = divert_packet;
                break;
        case MOD_QUIESCE:
                /*
                 * IPDIVERT may normally not be unloaded because of the
                 * potential race conditions.  Tell kldunload we can't be
                 * unloaded unless the unload is forced.
                 */
                err = EPERM;
                break;
        case MOD_UNLOAD:
                /*
                 * Forced unload.
                 *
                 * Module ipdivert can only be unloaded if no sockets are
                 * connected.  Maybe this can be changed later to forcefully
                 * disconnect any open sockets.
                 *
                 * XXXRW: Note that there is a slight race here, as a new
                 * socket open request could be spinning on the lock and then
                 * we destroy the lock.
                 *
                 * XXXGL: One more reason this code is incorrect is that it
                 * checks only the current vnet.
                 */
                DIVERT_LOCK();
                if (V_dcb_count != 0) {
                        DIVERT_UNLOCK();
                        err = EBUSY;
                        break;
                }
                DIVERT_UNLOCK();
                ip_divert_ptr = NULL;
                domain_remove(&divertdomain);
                break;
        default:
                err = EOPNOTSUPP;
                break;
        }
        return err;
}

static moduledata_t ipdivertmod = {
        "ipdivert",
        div_modevent,
        0
};

DECLARE_MODULE(ipdivert, ipdivertmod, SI_SUB_PROTO_FIREWALL, SI_ORDER_ANY);
MODULE_VERSION(ipdivert, 1);