/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2012 Gleb Smirnoff <glebius@FreeBSD.org>
 * Copyright (c) 1980, 1986, 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/param.h>
#include <sys/eventhandler.h>
#include <sys/malloc.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/socket.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/if_clone.h>
#include <net/radix.h>
#include <net/route.h>
#include <net/vnet.h>

#include <netlink/netlink.h>
#include <netlink/netlink_ctl.h>
#include <netlink/netlink_route.h>
#include <netlink/route/route_var.h>

/* Current IF_MAXUNIT expands maximum to 5 characters. */
#define IFCLOSIZ        (IFNAMSIZ - 5)

/*
 * Structure describing a `cloning' interface.
 *
 * List of locks
 * (c)          const until freeing
 * (d)          driver specific data, may need external protection.
 * (e)          locked by if_cloners_mtx
 * (i)          locked by ifc_mtx mtx
 */
struct if_clone {
        char ifc_name[IFCLOSIZ];        /* (c) Name of device, e.g. `gif' */
        struct unrhdr *ifc_unrhdr;      /* (c) alloc_unr(9) header */
        int ifc_maxunit;                /* (c) maximum unit number */
        int ifc_flags;
        long ifc_refcnt;                /* (i) Reference count. */
        LIST_HEAD(, ifnet) ifc_iflist;  /* (i) List of cloned interfaces */
        struct mtx ifc_mtx;             /* Mutex to protect members. */

        ifc_match_f *ifc_match;         /* (c) Matcher function */
        ifc_create_f *ifc_create;       /* (c) Creates new interface */
        ifc_destroy_f *ifc_destroy;     /* (c) Destroys cloned interface */

        ifc_create_nl_f *create_nl;     /* (c) Netlink creation handler */
        ifc_modify_nl_f *modify_nl;     /* (c) Netlink modification handler */
        ifc_dump_nl_f   *dump_nl;       /* (c) Netlink dump handler */

#ifdef CLONE_COMPAT_13
        /* (c) Driver specific cloning functions.  Called with no locks held. */
        union {
                struct {        /* advanced cloner */
                        ifc_create_t    *_ifc_create;
                        ifc_destroy_t   *_ifc_destroy;
                } A;
                struct {        /* simple cloner */
                        ifcs_create_t   *_ifcs_create;
                        ifcs_destroy_t  *_ifcs_destroy;
                        int             _ifcs_minifs;   /* minimum ifs */

                } S;
        } U;
#define ifca_create     U.A._ifc_create
#define ifca_destroy    U.A._ifc_destroy
#define ifcs_create     U.S._ifcs_create
#define ifcs_destroy    U.S._ifcs_destroy
#define ifcs_minifs     U.S._ifcs_minifs
#endif

        LIST_ENTRY(if_clone) ifc_list;  /* (e) On list of cloners */
};



static void     if_clone_free(struct if_clone *ifc);
static int      if_clone_createif_nl(struct if_clone *ifc, const char *name,
                    struct ifc_data_nl *ifd);

static int ifc_simple_match(struct if_clone *ifc, const char *name);
static int ifc_handle_unit(struct if_clone *ifc, char *name, size_t len, int *punit);
static struct if_clone *ifc_find_cloner(const char *name);
static struct if_clone *ifc_find_cloner_match(const char *name);

#ifdef CLONE_COMPAT_13
static int ifc_simple_create_wrapper(struct if_clone *ifc, char *name, size_t maxlen,
    struct ifc_data *ifc_data, struct ifnet **ifpp);
static int ifc_advanced_create_wrapper(struct if_clone *ifc, char *name, size_t maxlen,
    struct ifc_data *ifc_data, struct ifnet **ifpp);
#endif

static struct mtx if_cloners_mtx;
MTX_SYSINIT(if_cloners_lock, &if_cloners_mtx, "if_cloners lock", MTX_DEF);
VNET_DEFINE_STATIC(int, if_cloners_count);
VNET_DEFINE(LIST_HEAD(, if_clone), if_cloners) = LIST_HEAD_INITIALIZER();

#define V_if_cloners_count      VNET(if_cloners_count)
#define V_if_cloners            VNET(if_cloners)

#define IF_CLONERS_LOCK_ASSERT()        mtx_assert(&if_cloners_mtx, MA_OWNED)
#define IF_CLONERS_LOCK()               mtx_lock(&if_cloners_mtx)
#define IF_CLONERS_UNLOCK()             mtx_unlock(&if_cloners_mtx)

#define IF_CLONE_LOCK_INIT(ifc)         \
    mtx_init(&(ifc)->ifc_mtx, "if_clone lock", NULL, MTX_DEF)
#define IF_CLONE_LOCK_DESTROY(ifc)      mtx_destroy(&(ifc)->ifc_mtx)
#define IF_CLONE_LOCK_ASSERT(ifc)       mtx_assert(&(ifc)->ifc_mtx, MA_OWNED)
#define IF_CLONE_LOCK(ifc)              mtx_lock(&(ifc)->ifc_mtx)
#define IF_CLONE_UNLOCK(ifc)            mtx_unlock(&(ifc)->ifc_mtx)

#define IF_CLONE_ADDREF(ifc)                                            \
        do {                                                            \
                IF_CLONE_LOCK(ifc);                                     \
                IF_CLONE_ADDREF_LOCKED(ifc);                            \
                IF_CLONE_UNLOCK(ifc);                                   \
        } while (0)
#define IF_CLONE_ADDREF_LOCKED(ifc)                                     \
        do {                                                            \
                IF_CLONE_LOCK_ASSERT(ifc);                              \
                KASSERT((ifc)->ifc_refcnt >= 0,                         \
                    ("negative refcnt %ld", (ifc)->ifc_refcnt));        \
                (ifc)->ifc_refcnt++;                                    \
        } while (0)
#define IF_CLONE_REMREF(ifc)                                            \
        do {                                                            \
                IF_CLONE_LOCK(ifc);                                     \
                IF_CLONE_REMREF_LOCKED(ifc);                            \
        } while (0)
#define IF_CLONE_REMREF_LOCKED(ifc)                                     \
        do {                                                            \
                IF_CLONE_LOCK_ASSERT(ifc);                              \
                KASSERT((ifc)->ifc_refcnt > 0,                          \
                    ("bogus refcnt %ld", (ifc)->ifc_refcnt));           \
                if (--(ifc)->ifc_refcnt == 0) {                         \
                        IF_CLONE_UNLOCK(ifc);                           \
                        if_clone_free(ifc);                             \
                } else {                                                \
                        /* silently free the lock */                    \
                        IF_CLONE_UNLOCK(ifc);                           \
                }                                                       \
        } while (0)

#define IFC_IFLIST_INSERT(_ifc, _ifp)                                   \
        LIST_INSERT_HEAD(&_ifc->ifc_iflist, _ifp, if_clones)
#define IFC_IFLIST_REMOVE(_ifc, _ifp)                                   \
        LIST_REMOVE(_ifp, if_clones)

static MALLOC_DEFINE(M_CLONE, "clone", "interface cloning framework");

/*
 * Lookup and create a clone network interface.
 */
int
ifc_create_ifp(const char *name, struct ifc_data *ifd, struct ifnet **ifpp)
{
        struct if_clone *ifc = ifc_find_cloner_match(name);

        if (ifc == NULL)
                return (EINVAL);

        struct ifc_data_nl ifd_new = {
                .flags = ifd->flags,
                .unit = ifd->unit,
                .params = ifd->params,
        };

        int error = if_clone_createif_nl(ifc, name, &ifd_new);

        if (ifpp != NULL)
                *ifpp = ifd_new.ifp;

        return (error);
}

bool
ifc_create_ifp_nl(const char *name, struct ifc_data_nl *ifd)
{
        struct if_clone *ifc = ifc_find_cloner_match(name);
        if (ifc == NULL) {
                ifd->error = EINVAL;
                return (false);
        }

        ifd->error = if_clone_createif_nl(ifc, name, ifd);

        return (true);
}

int
if_clone_create(char *name, size_t len, caddr_t params)
{
        struct ifc_data ifd = { .params = params };
        struct ifnet *ifp;

        int error = ifc_create_ifp(name, &ifd, &ifp);

        if (error == 0)
                strlcpy(name, if_name(ifp), len);

        return (error);
}

bool
ifc_modify_ifp_nl(struct ifnet *ifp, struct ifc_data_nl *ifd)
{
        struct if_clone *ifc = ifc_find_cloner(ifp->if_dname);
        if (ifc == NULL) {
                ifd->error = EINVAL;
                return (false);
        }

        ifd->error = (*ifc->modify_nl)(ifp, ifd);
        return (true);
}

bool
ifc_dump_ifp_nl(struct ifnet *ifp, struct nl_writer *nw)
{
        struct if_clone *ifc = ifc_find_cloner(ifp->if_dname);
        if (ifc == NULL)
                return (false);

        (*ifc->dump_nl)(ifp, nw);
        return (true);
}

static int
ifc_create_ifp_nl_default(struct if_clone *ifc, char *name, size_t len,
    struct ifc_data_nl *ifd)
{
        struct ifc_data ifd_new = {
                .flags = ifd->flags,
                .unit = ifd->unit,
                .params = ifd->params,
        };

        return ((*ifc->ifc_create)(ifc, name, len, &ifd_new, &ifd->ifp));
}

static int
ifc_modify_ifp_nl_default(struct ifnet *ifp, struct ifc_data_nl *ifd)
{
        if (ifd->lattrs != NULL)
                return (nl_modify_ifp_generic(ifp, ifd->lattrs, ifd->bm, ifd->npt));
        return (0);
}

static void
ifc_dump_ifp_nl_default(struct ifnet *ifp, struct nl_writer *nw)
{
        int off = nlattr_add_nested(nw, IFLA_LINKINFO);

        if (off != 0) {
                nlattr_add_string(nw, IFLA_INFO_KIND, ifp->if_dname);
                nlattr_set_len(nw, off);
        }
}

void
ifc_link_ifp(struct if_clone *ifc, struct ifnet *ifp)
{

        if_addgroup(ifp, ifc->ifc_name);

        IF_CLONE_LOCK(ifc);
        IFC_IFLIST_INSERT(ifc, ifp);
        IF_CLONE_UNLOCK(ifc);
}

void
if_clone_addif(struct if_clone *ifc, struct ifnet *ifp)
{
        ifc_link_ifp(ifc, ifp);
}

bool
ifc_unlink_ifp(struct if_clone *ifc, struct ifnet *ifp)
{
        struct ifnet *ifcifp;

        IF_CLONE_LOCK(ifc);
        LIST_FOREACH(ifcifp, &ifc->ifc_iflist, if_clones) {
                if (ifcifp == ifp) {
                        IFC_IFLIST_REMOVE(ifc, ifp);
                        break;
                }
        }
        IF_CLONE_UNLOCK(ifc);

        if (ifcifp != NULL)
                if_delgroup(ifp, ifc->ifc_name);

        return (ifcifp != NULL);
}

static struct if_clone *
ifc_find_cloner_match(const char *name)
{
        struct if_clone *ifc;

        IF_CLONERS_LOCK();
        LIST_FOREACH(ifc, &V_if_cloners, ifc_list) {
                if (ifc->ifc_match(ifc, name))
                        break;
        }
        IF_CLONERS_UNLOCK();

        return (ifc);
}

static struct if_clone *
ifc_find_cloner(const char *name)
{
        struct if_clone *ifc;

        IF_CLONERS_LOCK();
        LIST_FOREACH(ifc, &V_if_cloners, ifc_list) {
                if (strcmp(ifc->ifc_name, name) == 0) {
                        break;
                }
        }
        IF_CLONERS_UNLOCK();

        return (ifc);
}

static struct if_clone *
ifc_find_cloner_in_vnet(const char *name, struct vnet *vnet)
{
        CURVNET_SET_QUIET(vnet);
        struct if_clone *ifc = ifc_find_cloner(name);
        CURVNET_RESTORE();

        return (ifc);
}

/*
 * Create a clone network interface.
 */
static int
if_clone_createif_nl(struct if_clone *ifc, const char *ifname, struct ifc_data_nl *ifd)
{
        char name[IFNAMSIZ];
        int error;

        strlcpy(name, ifname, sizeof(name));

        if (ifunit(name) != NULL)
                return (EEXIST);

        if (ifc->ifc_flags & IFC_F_AUTOUNIT) {
                if ((error = ifc_handle_unit(ifc, name, sizeof(name), &ifd->unit)) != 0)
                        return (error);
        }

        if (ifd->lattrs != NULL)
                error = (*ifc->create_nl)(ifc, name, sizeof(name), ifd);
        else
                error = ifc_create_ifp_nl_default(ifc, name, sizeof(name), ifd);
        if (error != 0) {
                if (ifc->ifc_flags & IFC_F_AUTOUNIT)
                        ifc_free_unit(ifc, ifd->unit);
                return (error);
        }

        MPASS(ifd->ifp != NULL);
        if_clone_addif(ifc, ifd->ifp);

        if (ifd->lattrs != NULL)
                error = (*ifc->modify_nl)(ifd->ifp, ifd);

        return (error);
}

/*
 * Lookup and destroy a clone network interface.
 */
int
if_clone_destroy(const char *name)
{
        int err;
        struct if_clone *ifc;
        struct ifnet *ifp;

        ifp = ifunit_ref(name);
        if (ifp == NULL)
                return (ENXIO);

        ifc = ifc_find_cloner_in_vnet(ifp->if_dname, ifp->if_home_vnet);
        if (ifc == NULL) {
                if_rele(ifp);
                return (EINVAL);
        }

        err = if_clone_destroyif(ifc, ifp);
        if_rele(ifp);
        return err;
}

/*
 * Destroy a clone network interface.
 */
static int
if_clone_destroyif_flags(struct if_clone *ifc, struct ifnet *ifp, uint32_t flags)
{
        int err;

        /*
         * Given that the cloned ifnet might be attached to a different
         * vnet from where its cloner was registered, we have to
         * switch to the vnet context of the target vnet.
         */
        CURVNET_SET_QUIET(ifp->if_vnet);

        if (!ifc_unlink_ifp(ifc, ifp)) {
                CURVNET_RESTORE();
                return (ENXIO);         /* ifp is not on the list. */
        }

        int unit = ifp->if_dunit;
        err = (*ifc->ifc_destroy)(ifc, ifp, flags);

        if (err != 0)
                ifc_link_ifp(ifc, ifp);
        else if (ifc->ifc_flags & IFC_F_AUTOUNIT)
                ifc_free_unit(ifc, unit);
        CURVNET_RESTORE();
        return (err);
}

int
if_clone_destroyif(struct if_clone *ifc, struct ifnet *ifp)
{
        return (if_clone_destroyif_flags(ifc, ifp, 0));
}

static struct if_clone *
if_clone_alloc(const char *name, int maxunit)
{
        struct if_clone *ifc;

        KASSERT(name != NULL, ("%s: no name\n", __func__));
        MPASS(maxunit >= 0);

        ifc = malloc(sizeof(struct if_clone), M_CLONE, M_WAITOK | M_ZERO);
        strncpy(ifc->ifc_name, name, IFCLOSIZ-1);
        IF_CLONE_LOCK_INIT(ifc);
        IF_CLONE_ADDREF(ifc);
        ifc->ifc_maxunit = maxunit;
        ifc->ifc_unrhdr = new_unrhdr(0, ifc->ifc_maxunit, &ifc->ifc_mtx);
        LIST_INIT(&ifc->ifc_iflist);

        ifc->create_nl = ifc_create_ifp_nl_default;
        ifc->modify_nl = ifc_modify_ifp_nl_default;
        ifc->dump_nl = ifc_dump_ifp_nl_default;

        return (ifc);
}

static int
if_clone_attach(struct if_clone *ifc)
{
        struct if_clone *ifc1;

        IF_CLONERS_LOCK();
        LIST_FOREACH(ifc1, &V_if_cloners, ifc_list)
                if (strcmp(ifc->ifc_name, ifc1->ifc_name) == 0) {
                        IF_CLONERS_UNLOCK();
                        IF_CLONE_REMREF(ifc);
                        return (EEXIST);
                }
        LIST_INSERT_HEAD(&V_if_cloners, ifc, ifc_list);
        V_if_cloners_count++;
        IF_CLONERS_UNLOCK();

        return (0);
}

struct if_clone *
ifc_attach_cloner(const char *name, struct if_clone_addreq *req)
{
        int maxunit;
        struct if_clone *ifc;

        if (req->create_f == NULL || req->destroy_f == NULL)
                return (NULL);
        if (strnlen(name, IFCLOSIZ) >= (IFCLOSIZ - 1))
                return (NULL);

        maxunit = (req->flags & IFC_F_LIMITUNIT) ? req->maxunit : IF_MAXUNIT;
        ifc = if_clone_alloc(name, maxunit);
        ifc->ifc_match = req->match_f != NULL ? req->match_f : ifc_simple_match;
        ifc->ifc_create = req->create_f;
        ifc->ifc_destroy = req->destroy_f;
        ifc->ifc_flags = (req->flags & IFC_F_AUTOUNIT);

        if (req->version == 2) {
                struct if_clone_addreq_v2 *req2 = (struct if_clone_addreq_v2 *)req;

                ifc->create_nl = req2->create_nl_f;
                ifc->modify_nl = req2->modify_nl_f;
                if (req2->dump_nl_f != NULL)
                        ifc->dump_nl = req2->dump_nl_f;
                else
                        ifc->dump_nl = ifc_dump_ifp_nl_default;
        }

        if (if_clone_attach(ifc) != 0)
                return (NULL);

        EVENTHANDLER_INVOKE(if_clone_event, ifc);

        return (ifc);
}

void
ifc_detach_cloner(struct if_clone *ifc)
{
        if_clone_detach(ifc);
}


#ifdef CLONE_COMPAT_13

static int
ifc_advanced_create_wrapper(struct if_clone *ifc, char *name, size_t maxlen,
    struct ifc_data *ifc_data, struct ifnet **ifpp)
{
        int error = ifc->ifca_create(ifc, name, maxlen, ifc_data->params);

        if (error == 0)
                *ifpp = ifunit(name);
        return (error);
}

static int
ifc_advanced_destroy_wrapper(struct if_clone *ifc, struct ifnet *ifp, uint32_t flags)
{
        if (ifc->ifca_destroy == NULL)
                return (ENOTSUP);
        return (ifc->ifca_destroy(ifc, ifp));
}

struct if_clone *
if_clone_advanced(const char *name, u_int maxunit, ifc_match_t match,
        ifc_create_t create, ifc_destroy_t destroy)
{
        struct if_clone *ifc;

        ifc = if_clone_alloc(name, maxunit ? maxunit : IF_MAXUNIT);
        ifc->ifc_match = match;
        ifc->ifc_create = ifc_advanced_create_wrapper;
        ifc->ifc_destroy = ifc_advanced_destroy_wrapper;
        ifc->ifca_destroy = destroy;
        ifc->ifca_create = create;

        if (if_clone_attach(ifc) != 0)
                return (NULL);

        EVENTHANDLER_INVOKE(if_clone_event, ifc);

        return (ifc);
}

static int
ifc_simple_create_wrapper(struct if_clone *ifc, char *name, size_t maxlen,
    struct ifc_data *ifc_data, struct ifnet **ifpp)
{
        int unit = 0;

        ifc_name2unit(name, &unit);
        int error = ifc->ifcs_create(ifc, unit, ifc_data->params);
        if (error == 0)
                *ifpp = ifunit(name);
        return (error);
}

static int
ifc_simple_destroy_wrapper(struct if_clone *ifc, struct ifnet *ifp, uint32_t flags)
{
        if (ifp->if_dunit < ifc->ifcs_minifs && (flags & IFC_F_FORCE) == 0)
                return (EINVAL);

        ifc->ifcs_destroy(ifp);
        return (0);
}

struct if_clone *
if_clone_simple(const char *name, ifcs_create_t create, ifcs_destroy_t destroy,
        u_int minifs)
{
        struct if_clone *ifc;
        u_int unit;

        ifc = if_clone_alloc(name, IF_MAXUNIT);
        ifc->ifc_match = ifc_simple_match;
        ifc->ifc_create = ifc_simple_create_wrapper;
        ifc->ifc_destroy = ifc_simple_destroy_wrapper;
        ifc->ifcs_create = create;
        ifc->ifcs_destroy = destroy;
        ifc->ifcs_minifs = minifs;
        ifc->ifc_flags = IFC_F_AUTOUNIT;

        if (if_clone_attach(ifc) != 0)
                return (NULL);

        for (unit = 0; unit < minifs; unit++) {
                char name[IFNAMSIZ];
                int error __unused;
                struct ifc_data_nl ifd = {};

                snprintf(name, IFNAMSIZ, "%s%d", ifc->ifc_name, unit);
                error = if_clone_createif_nl(ifc, name, &ifd);
                KASSERT(error == 0,
                    ("%s: failed to create required interface %s",
                    __func__, name));
        }

        EVENTHANDLER_INVOKE(if_clone_event, ifc);

        return (ifc);
}
#endif

/*
 * Unregister a network interface cloner.
 */
void
if_clone_detach(struct if_clone *ifc)
{

        IF_CLONERS_LOCK();
        LIST_REMOVE(ifc, ifc_list);
        V_if_cloners_count--;
        IF_CLONERS_UNLOCK();

        /* destroy all interfaces for this cloner */
        while (!LIST_EMPTY(&ifc->ifc_iflist))
                if_clone_destroyif_flags(ifc, LIST_FIRST(&ifc->ifc_iflist), IFC_F_FORCE);

        IF_CLONE_REMREF(ifc);
}

static void
if_clone_free(struct if_clone *ifc)
{

        KASSERT(LIST_EMPTY(&ifc->ifc_iflist),
            ("%s: ifc_iflist not empty", __func__));

        IF_CLONE_LOCK_DESTROY(ifc);
        delete_unrhdr(ifc->ifc_unrhdr);
        free(ifc, M_CLONE);
}

/*
 * Provide list of interface cloners to userspace.
 */
int
if_clone_list(struct if_clonereq *ifcr)
{
        char *buf, *dst, *outbuf = NULL;
        struct if_clone *ifc;
        int buf_count, count, err = 0;

        if (ifcr->ifcr_count < 0)
                return (EINVAL);

        IF_CLONERS_LOCK();
        /*
         * Set our internal output buffer size.  We could end up not
         * reporting a cloner that is added between the unlock and lock
         * below, but that's not a major problem.  Not caping our
         * allocation to the number of cloners actually in the system
         * could be because that would let arbitrary users cause us to
         * allocate arbitrary amounts of kernel memory.
         */
        buf_count = (V_if_cloners_count < ifcr->ifcr_count) ?
            V_if_cloners_count : ifcr->ifcr_count;
        IF_CLONERS_UNLOCK();

        outbuf = malloc(IFNAMSIZ*buf_count, M_CLONE, M_WAITOK | M_ZERO);

        IF_CLONERS_LOCK();

        ifcr->ifcr_total = V_if_cloners_count;
        if ((dst = ifcr->ifcr_buffer) == NULL) {
                /* Just asking how many there are. */
                goto done;
        }
        count = (V_if_cloners_count < buf_count) ?
            V_if_cloners_count : buf_count;

        for (ifc = LIST_FIRST(&V_if_cloners), buf = outbuf;
            ifc != NULL && count != 0;
            ifc = LIST_NEXT(ifc, ifc_list), count--, buf += IFNAMSIZ) {
                strlcpy(buf, ifc->ifc_name, IFNAMSIZ);
        }

done:
        IF_CLONERS_UNLOCK();
        if (err == 0 && dst != NULL)
                err = copyout(outbuf, dst, buf_count*IFNAMSIZ);
        if (outbuf != NULL)
                free(outbuf, M_CLONE);
        return (err);
}

#ifdef VIMAGE
/*
 * if_clone_restoregroup() is used in context of if_vmove().
 *
 * Since if_detach_internal() has removed the interface from ALL groups, we
 * need to "restore" interface membership in the cloner's group.  Note that
 * interface belongs to cloner in its home vnet, so we first find the original
 * cloner, and then we confirm that cloner with the same name exists in the
 * current vnet.
 */
void
if_clone_restoregroup(struct ifnet *ifp)
{
        struct if_clone *ifc;
        struct ifnet *ifcifp;
        char ifc_name[IFCLOSIZ] = { [0] = '\0' };

        CURVNET_SET_QUIET(ifp->if_home_vnet);
        IF_CLONERS_LOCK();
        LIST_FOREACH(ifc, &V_if_cloners, ifc_list) {
                IF_CLONE_LOCK(ifc);
                LIST_FOREACH(ifcifp, &ifc->ifc_iflist, if_clones) {
                        if (ifp == ifcifp) {
                                strncpy(ifc_name, ifc->ifc_name, IFCLOSIZ-1);
                                break;
                        }
                }
                IF_CLONE_UNLOCK(ifc);
                if (ifc_name[0] != '\0')
                        break;
        }
        CURVNET_RESTORE();
        LIST_FOREACH(ifc, &V_if_cloners, ifc_list)
                if (strcmp(ifc->ifc_name, ifc_name) == 0)
                        break;
        IF_CLONERS_UNLOCK();

        if (ifc != NULL)
                if_addgroup(ifp, ifc_name);
}
#endif

/*
 * A utility function to extract unit numbers from interface names of
 * the form name###.
 *
 * Returns 0 on success and an error on failure.
 */
int
ifc_name2unit(const char *name, int *unit)
{
        const char      *cp;
        int             cutoff = INT_MAX / 10;
        int             cutlim = INT_MAX % 10;

        for (cp = name; *cp != '\0' && (*cp < '0' || *cp > '9'); cp++)
                ;
        if (*cp == '\0') {
                *unit = -1;
        } else if (cp[0] == '0' && cp[1] != '\0') {
                /* Disallow leading zeroes. */
                return (EINVAL);
        } else {
                for (*unit = 0; *cp != '\0'; cp++) {
                        if (*cp < '0' || *cp > '9') {
                                /* Bogus unit number. */
                                return (EINVAL);
                        }
                        if (*unit > cutoff ||
                            (*unit == cutoff && *cp - '0' > cutlim))
                                return (EINVAL);
                        *unit = (*unit * 10) + (*cp - '0');
                }
        }

        return (0);
}

static int
ifc_alloc_unit_specific(struct if_clone *ifc, int *unit)
{
        char name[IFNAMSIZ];

        if (*unit > ifc->ifc_maxunit)
                return (ENOSPC);

        if (alloc_unr_specific(ifc->ifc_unrhdr, *unit) == -1)
                return (EEXIST);

        snprintf(name, IFNAMSIZ, "%s%d", ifc->ifc_name, *unit);
        if (ifunit(name) != NULL) {
                free_unr(ifc->ifc_unrhdr, *unit);
                return (EEXIST);
        }

        IF_CLONE_ADDREF(ifc);

        return (0);
}

static int
ifc_alloc_unit_next(struct if_clone *ifc, int *unit)
{
        int error;

        *unit = alloc_unr(ifc->ifc_unrhdr);
        if (*unit == -1)
                return (ENOSPC);

        free_unr(ifc->ifc_unrhdr, *unit);
        for (;;) {
                error = ifc_alloc_unit_specific(ifc, unit);
                if (error != EEXIST)
                        break;

                (*unit)++;
        }

        return (error);
}

int
ifc_alloc_unit(struct if_clone *ifc, int *unit)
{
        if (*unit < 0)
                return (ifc_alloc_unit_next(ifc, unit));
        else
                return (ifc_alloc_unit_specific(ifc, unit));
}

void
ifc_free_unit(struct if_clone *ifc, int unit)
{

        free_unr(ifc->ifc_unrhdr, unit);
        IF_CLONE_REMREF(ifc);
}

static int
ifc_simple_match(struct if_clone *ifc, const char *name)
{
        const char *cp;
        int i;

        /* Match the name */
        for (cp = name, i = 0; i < strlen(ifc->ifc_name); i++, cp++) {
                if (ifc->ifc_name[i] != *cp)
                        return (0);
        }

        /* Make sure there's a unit number or nothing after the name */
        for (; *cp != '\0'; cp++) {
                if (*cp < '0' || *cp > '9')
                        return (0);
        }

        return (1);
}

static int
ifc_handle_unit(struct if_clone *ifc, char *name, size_t len, int *punit)
{
        char *dp;
        int wildcard;
        int unit;
        int err;

        err = ifc_name2unit(name, &unit);
        if (err != 0)
                return (err);

        wildcard = (unit < 0);

        err = ifc_alloc_unit(ifc, &unit);
        if (err != 0)
                return (err);

        /* In the wildcard case, we need to update the name. */
        if (wildcard) {
                for (dp = name; *dp != '\0'; dp++);
                if (snprintf(dp, len - (dp-name), "%d", unit) >
                    len - (dp-name) - 1) {
                        /*
                         * This can only be a programmer error and
                         * there's no straightforward way to recover if
                         * it happens.
                         */
                        panic("if_clone_create(): interface name too long");
                }
        }
        *punit = unit;

        return (0);
}

int
ifc_copyin(const struct ifc_data *ifd, void *target, size_t len)
{
        if (ifd->params == NULL)
                return (EINVAL);

        if (ifd->flags & IFC_F_SYSSPACE) {
                memcpy(target, ifd->params, len);
                return (0);
        } else
                return (copyin(ifd->params, target, len));
}