8437 dlmgmt_setzoneid() doesn't enforce uniqueness

[unleashed.git] / usr / src / cmd / dlmgmtd / dlmgmt_door.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2017 Joyent, Inc.
 */

/*
 * Main door handler functions used by dlmgmtd to process the different door
 * call requests. Door call requests can come from the user-land applications,
 * or from the kernel.
 *
 * Note on zones handling:
 *
 * There are two zoneid's associated with a link.  One is the zoneid of the
 * zone in which the link was created (ll_zoneid in the dlmgmt_link_t), and
 * the other is the zoneid of the zone where the link is currently assigned
 * (the "zone" link property).  The two can be different if a datalink is
 * created in the global zone and subsequently assigned to a non-global zone
 * via zonecfg or via explicitly setting the "zone" link property.
 *
 * Door clients can see links that were created in their zone, and links that
 * are currently assigned to their zone.  Door clients in a zone can only
 * modify links that were created in their zone.
 *
 * The datalink ID space is global, while each zone has its own datalink name
 * space.  This allows each zone to have complete freedom over the names that
 * they assign to links created within the zone.
 */

#include <assert.h>
#include <alloca.h>
#include <errno.h>
#include <priv_utils.h>
#include <stdlib.h>
#include <strings.h>
#include <syslog.h>
#include <sys/sysevent/eventdefs.h>
#include <zone.h>
#include <libsysevent.h>
#include <libdlmgmt.h>
#include <librcm.h>
#include "dlmgmt_impl.h"

typedef void dlmgmt_door_handler_t(void *, void *, size_t *, zoneid_t,
    ucred_t *);

typedef struct dlmgmt_door_info_s {
        uint_t                  di_cmd;
        size_t                  di_reqsz;
        size_t                  di_acksz;
        dlmgmt_door_handler_t   *di_handler;
} dlmgmt_door_info_t;

/*
 * Check if the caller has the required privileges to operate on a link of the
 * given class.
 */
static int
dlmgmt_checkprivs(datalink_class_t class, ucred_t *cred)
{
        const priv_set_t *eset;

        eset = ucred_getprivset(cred, PRIV_EFFECTIVE);
        if (eset != NULL && ((class == DATALINK_CLASS_IPTUN &&
            priv_ismember(eset, PRIV_SYS_IPTUN_CONFIG)) ||
            priv_ismember(eset, PRIV_SYS_DL_CONFIG) ||
            priv_ismember(eset, PRIV_SYS_NET_CONFIG)))
                return (0);
        return (EACCES);
}

static dlmgmt_link_t *
dlmgmt_getlink_by_dev(char *devname, zoneid_t zoneid)
{
        dlmgmt_link_t *linkp = avl_first(&dlmgmt_id_avl);

        for (; linkp != NULL; linkp = AVL_NEXT(&dlmgmt_id_avl, linkp)) {
                if (link_is_visible(linkp, zoneid) &&
                    (linkp->ll_class == DATALINK_CLASS_PHYS) &&
                    linkattr_equal(&(linkp->ll_head), FDEVNAME, devname,
                    strlen(devname) + 1)) {
                        return (linkp);
                }
        }
        return (NULL);
}

/*
 * Post the EC_DATALINK sysevent for the given linkid. This sysevent will
 * be consumed by the datalink sysevent module.
 */
static void
dlmgmt_post_sysevent(const char *subclass, datalink_id_t linkid,
    boolean_t reconfigured)
{
        nvlist_t        *nvl = NULL;
        sysevent_id_t   eid;
        int             err;

        if (((err = nvlist_alloc(&nvl, NV_UNIQUE_NAME_TYPE, 0)) != 0) ||
            ((err = nvlist_add_uint64(nvl, RCM_NV_LINKID, linkid)) != 0) ||
            ((err = nvlist_add_boolean_value(nvl, RCM_NV_RECONFIGURED,
            reconfigured)) != 0)) {
                goto done;
        }

        if (sysevent_post_event(EC_DATALINK, (char *)subclass, SUNW_VENDOR,
            (char *)progname, nvl, &eid) == -1) {
                err = errno;
        }

done:
        if (err != 0) {
                dlmgmt_log(LOG_WARNING, "dlmgmt_post_sysevent(%d) failed: %s",
                    linkid, strerror(err));
        }
        nvlist_free(nvl);
}

/* ARGSUSED */
static void
dlmgmt_upcall_create(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_upcall_arg_create_t *create = argp;
        dlmgmt_create_retval_t  *retvalp = retp;
        datalink_class_t        class;
        uint32_t                media;
        dlmgmt_link_t           *linkp;
        char                    link[MAXLINKNAMELEN];
        uint32_t                flags;
        int                     err = 0;
        boolean_t               created = B_FALSE;
        boolean_t               reconfigured = B_FALSE;

        /*
         * Determine whether this link is persistent. Note that this request
         * is coming from kernel so this link must be active.
         */
        flags = DLMGMT_ACTIVE | (create->ld_persist ? DLMGMT_PERSIST : 0);

        class = create->ld_class;
        media = create->ld_media;

        /*
         * Hold the writer lock to update the link table.
         */
        dlmgmt_table_lock(B_TRUE);

        if ((err = dlmgmt_checkprivs(class, cred)) != 0)
                goto done;

        /*
         * Check to see whether this is the reattachment of an existing
         * physical link. If so, return its linkid.
         */
        if ((class == DATALINK_CLASS_PHYS) && (linkp =
            dlmgmt_getlink_by_dev(create->ld_devname, zoneid)) != NULL) {
                if (linkattr_equal(&(linkp->ll_head), FPHYMAJ,
                    &create->ld_phymaj, sizeof (uint64_t)) &&
                    linkattr_equal(&(linkp->ll_head), FPHYINST,
                    &create->ld_phyinst, sizeof (uint64_t)) &&
                    (linkp->ll_flags & flags) == flags) {
                        /*
                         * If nothing has been changed, directly return.
                         */
                        goto noupdate;
                }

                err = linkattr_set(&(linkp->ll_head), FPHYMAJ,
                    &create->ld_phymaj, sizeof (uint64_t), DLADM_TYPE_UINT64);
                if (err != 0)
                        goto done;

                err = linkattr_set(&(linkp->ll_head), FPHYINST,
                    &create->ld_phyinst, sizeof (uint64_t), DLADM_TYPE_UINT64);
                if (err != 0)
                        goto done;

                /*
                 * This is a device that is dynamic reconfigured.
                 */
                if ((linkp->ll_flags & DLMGMT_ACTIVE) == 0)
                        reconfigured = B_TRUE;

                if ((err = link_activate(linkp)) != 0)
                        goto done;
                linkp->ll_flags |= flags;
                linkp->ll_gen++;

                goto done;
        }

        if ((err = dlmgmt_create_common(create->ld_devname, class, media,
            zoneid, flags, &linkp)) == EEXIST) {
                /*
                 * The link name already exists. Return error if this is a
                 * non-physical link (in that case, the link name must be
                 * the same as the given name).
                 */
                if (class != DATALINK_CLASS_PHYS)
                        goto done;

                /*
                 * The physical link's name already exists, request
                 * a suggested link name: net<nextppa>
                 */
                err = dlmgmt_generate_name("net", link, MAXLINKNAMELEN, zoneid);
                if (err != 0)
                        goto done;

                err = dlmgmt_create_common(link, class, media, zoneid, flags,
                    &linkp);
        }

        if (err != 0)
                goto done;

        created = B_TRUE;

        /*
         * This is a new link.  Only need to persist link attributes for
         * physical links.
         */
        if (class == DATALINK_CLASS_PHYS &&
            (((err = linkattr_set(&linkp->ll_head, FDEVNAME, create->ld_devname,
            strlen(create->ld_devname) + 1, DLADM_TYPE_STR)) != 0) ||
            ((err = linkattr_set(&linkp->ll_head, FPHYMAJ, &create->ld_phymaj,
            sizeof (uint64_t), DLADM_TYPE_UINT64)) != 0) ||
            ((err = linkattr_set(&linkp->ll_head, FPHYINST, &create->ld_phyinst,
            sizeof (uint64_t), DLADM_TYPE_UINT64)) != 0))) {
                (void) dlmgmt_destroy_common(linkp, flags);
        }

done:
        if ((err == 0) && ((err = dlmgmt_write_db_entry(linkp->ll_link, linkp,
            linkp->ll_flags)) != 0) && created) {
                (void) dlmgmt_destroy_common(linkp, flags);
        }

noupdate:
        if (err == 0)
                retvalp->lr_linkid = linkp->ll_linkid;

        dlmgmt_table_unlock();

        if ((err == 0) && (class == DATALINK_CLASS_PHYS)) {
                /*
                 * Post the ESC_DATALINK_PHYS_ADD sysevent. This sysevent
                 * is consumed by the datalink sysevent module which in
                 * turn generates the RCM_RESOURCE_LINK_NEW RCM event.
                 */
                dlmgmt_post_sysevent(ESC_DATALINK_PHYS_ADD,
                    retvalp->lr_linkid, reconfigured);
        }

        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_upcall_update(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_upcall_arg_update_t      *update = argp;
        dlmgmt_update_retval_t          *retvalp = retp;
        uint32_t                        media = update->ld_media;
        dlmgmt_link_t                   *linkp;
        int                             err = 0;

        /*
         * Hold the writer lock to update the link table.
         */
        dlmgmt_table_lock(B_TRUE);

        /*
         * Check to see whether this is the reattachment of an existing
         * physical link. If so, return its linkid.
         */
        if ((linkp = dlmgmt_getlink_by_dev(update->ld_devname, zoneid)) ==
            NULL) {
                err = ENOENT;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(linkp->ll_class, cred)) != 0)
                goto done;

        retvalp->lr_linkid = linkp->ll_linkid;
        retvalp->lr_media = media;
        if (linkp->ll_media != media && linkp->ll_media != DL_OTHER) {
                /*
                 * Assume a DL_ETHER link ce0, a DL_WIFI link ath0
                 * 1. # dladm rename-link ce0 net0
                 * 2. DR out ce0. net0 is down.
                 * 3. use rename-link to have the ath0 device inherit
                 *    the configuration from net0
                 *    # dladm rename-link ath0 net0
                 * 4. DR in ath0.
                 * As ath0 and ce0 do not have the same media type, ath0
                 * cannot inherit the configuration of net0.
                 */
                err = EEXIST;

                /*
                 * Return the media type of the existing link to indicate the
                 * reason for the name conflict.
                 */
                retvalp->lr_media = linkp->ll_media;
                goto done;
        }

        if (update->ld_novanity &&
            (strcmp(update->ld_devname, linkp->ll_link) != 0)) {
                /*
                 * Return an error if this is a physical link that does not
                 * support vanity naming, but the link name is not the same
                 * as the given device name.
                 */
                err = EEXIST;
                goto done;
        }

        if (linkp->ll_media != media) {
                linkp->ll_media = media;
                linkp->ll_gen++;
                (void) dlmgmt_write_db_entry(linkp->ll_link, linkp,
                    linkp->ll_flags);
        }

done:
        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_upcall_destroy(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_upcall_arg_destroy_t     *destroy = argp;
        dlmgmt_destroy_retval_t         *retvalp = retp;
        datalink_id_t                   linkid = destroy->ld_linkid;
        dlmgmt_link_t                   *linkp = NULL;
        uint32_t                        flags, dflags = 0;
        int                             err = 0;

        flags = DLMGMT_ACTIVE | (destroy->ld_persist ? DLMGMT_PERSIST : 0);

        /*
         * Hold the writer lock to update the link table.
         */
        dlmgmt_table_lock(B_TRUE);

        if ((linkp = link_by_id(linkid, zoneid)) == NULL) {
                err = ENOENT;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(linkp->ll_class, cred)) != 0)
                goto done;

        if (((linkp->ll_flags & flags) & DLMGMT_ACTIVE) != 0) {
                if ((err = dlmgmt_delete_db_entry(linkp, DLMGMT_ACTIVE)) != 0)
                        goto done;
                dflags |= DLMGMT_ACTIVE;
        }

        if (((linkp->ll_flags & flags) & DLMGMT_PERSIST) != 0) {
                if ((err = dlmgmt_delete_db_entry(linkp, DLMGMT_PERSIST)) != 0)
                        goto done;
                dflags |= DLMGMT_PERSIST;
        }

        err = dlmgmt_destroy_common(linkp, flags);
done:
        if (err != 0 && dflags != 0)
                (void) dlmgmt_write_db_entry(linkp->ll_link, linkp, dflags);

        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_getname(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_getname_t   *getname = argp;
        dlmgmt_getname_retval_t *retvalp = retp;
        dlmgmt_link_t           *linkp;
        int                     err = 0;

        /*
         * Hold the reader lock to access the link
         */
        dlmgmt_table_lock(B_FALSE);
        if ((linkp = link_by_id(getname->ld_linkid, zoneid)) == NULL) {
                err = ENOENT;
        } else if (strlcpy(retvalp->lr_link, linkp->ll_link, MAXLINKNAMELEN) >=
            MAXLINKNAMELEN) {
                err = ENOSPC;
        } else {
                retvalp->lr_flags = linkp->ll_flags;
                retvalp->lr_class = linkp->ll_class;
                retvalp->lr_media = linkp->ll_media;
        }

        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_getlinkid(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_getlinkid_t *getlinkid = argp;
        dlmgmt_getlinkid_retval_t *retvalp = retp;
        dlmgmt_link_t           *linkp;
        int                     err = 0;

        /*
         * Hold the reader lock to access the link
         */
        dlmgmt_table_lock(B_FALSE);

        if ((linkp = link_by_name(getlinkid->ld_link, zoneid)) == NULL) {
                /*
                 * The link does not exist in this zone.
                 */
                err = ENOENT;
                goto done;
        }

        retvalp->lr_linkid = linkp->ll_linkid;
        retvalp->lr_flags = linkp->ll_flags;
        retvalp->lr_class = linkp->ll_class;
        retvalp->lr_media = linkp->ll_media;

done:
        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_getnext(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_getnext_t   *getnext = argp;
        dlmgmt_getnext_retval_t *retvalp = retp;
        dlmgmt_link_t           link, *linkp;
        avl_index_t             where;
        int                     err = 0;

        /*
         * Hold the reader lock to access the link
         */
        dlmgmt_table_lock(B_FALSE);

        link.ll_linkid = (getnext->ld_linkid + 1);
        if ((linkp = avl_find(&dlmgmt_id_avl, &link, &where)) == NULL)
                linkp = avl_nearest(&dlmgmt_id_avl, where, AVL_AFTER);

        for (; linkp != NULL; linkp = AVL_NEXT(&dlmgmt_id_avl, linkp)) {
                if (!link_is_visible(linkp, zoneid))
                        continue;
                if ((linkp->ll_class & getnext->ld_class) &&
                    (linkp->ll_flags & getnext->ld_flags) &&
                    DATALINK_MEDIA_ACCEPTED(getnext->ld_dmedia,
                    linkp->ll_media))
                        break;
        }

        if (linkp == NULL) {
                err = ENOENT;
        } else {
                retvalp->lr_linkid = linkp->ll_linkid;
                retvalp->lr_class = linkp->ll_class;
                retvalp->lr_media = linkp->ll_media;
                retvalp->lr_flags = linkp->ll_flags;
        }

        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_upcall_getattr(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_upcall_arg_getattr_t     *getattr = argp;
        dlmgmt_getattr_retval_t         *retvalp = retp;
        dlmgmt_link_t                   *linkp;

        /*
         * Hold the reader lock to access the link
         */
        dlmgmt_table_lock(B_FALSE);
        if ((linkp = link_by_id(getattr->ld_linkid, zoneid)) == NULL) {
                retvalp->lr_err = ENOENT;
        } else {
                retvalp->lr_err = dlmgmt_getattr_common(&linkp->ll_head,
                    getattr->ld_attr, retvalp);
        }
        dlmgmt_table_unlock();
}

/* ARGSUSED */
static void
dlmgmt_createid(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_createid_t  *createid = argp;
        dlmgmt_createid_retval_t *retvalp = retp;
        dlmgmt_link_t           *linkp;
        datalink_id_t           linkid = DATALINK_INVALID_LINKID;
        char                    link[MAXLINKNAMELEN];
        int                     err;

        /*
         * Hold the writer lock to update the dlconf table.
         */
        dlmgmt_table_lock(B_TRUE);

        if ((err = dlmgmt_checkprivs(createid->ld_class, cred)) != 0)
                goto done;

        if (createid->ld_prefix) {
                err = dlmgmt_generate_name(createid->ld_link, link,
                    MAXLINKNAMELEN, zoneid);
                if (err != 0)
                        goto done;

                err = dlmgmt_create_common(link, createid->ld_class,
                    createid->ld_media, zoneid, createid->ld_flags, &linkp);
        } else {
                err = dlmgmt_create_common(createid->ld_link,
                    createid->ld_class, createid->ld_media, zoneid,
                    createid->ld_flags, &linkp);
        }

        if (err == 0) {
                /*
                 * Keep the active mapping.
                 */
                linkid = linkp->ll_linkid;
                if (createid->ld_flags & DLMGMT_ACTIVE) {
                        (void) dlmgmt_write_db_entry(linkp->ll_link, linkp,
                            DLMGMT_ACTIVE);
                }
        }

done:
        dlmgmt_table_unlock();
        retvalp->lr_linkid = linkid;
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_destroyid(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_destroyid_t *destroyid = argp;
        dlmgmt_destroyid_retval_t *retvalp = retp;
        datalink_id_t           linkid = destroyid->ld_linkid;
        uint32_t                flags = destroyid->ld_flags;
        dlmgmt_link_t           *linkp = NULL;
        int                     err = 0;

        /*
         * Hold the writer lock to update the link table.
         */
        dlmgmt_table_lock(B_TRUE);
        if ((linkp = link_by_id(linkid, zoneid)) == NULL) {
                err = ENOENT;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(linkp->ll_class, cred)) != 0)
                goto done;

        /*
         * Delete the active mapping.
         */
        if (flags & DLMGMT_ACTIVE)
                err = dlmgmt_delete_db_entry(linkp, DLMGMT_ACTIVE);
        if (err == 0)
                err = dlmgmt_destroy_common(linkp, flags);
done:
        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/*
 * Remap a linkid to a given link name, i.e., rename an existing link1
 * (ld_linkid) to a non-existent link2 (ld_link): rename link1's name to
 * the given link name.
 */
/* ARGSUSED */
static void
dlmgmt_remapid(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_remapid_t   *remapid = argp;
        dlmgmt_remapid_retval_t *retvalp = retp;
        dlmgmt_link_t           *linkp;
        char                    oldname[MAXLINKNAMELEN];
        boolean_t               renamed = B_FALSE;
        int                     err = 0;

        if (!dladm_valid_linkname(remapid->ld_link)) {
                retvalp->lr_err = EINVAL;
                return;
        }

        /*
         * Hold the writer lock to update the link table.
         */
        dlmgmt_table_lock(B_TRUE);
        if ((linkp = link_by_id(remapid->ld_linkid, zoneid)) == NULL) {
                err = ENOENT;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(linkp->ll_class, cred)) != 0)
                goto done;

        if (link_by_name(remapid->ld_link, linkp->ll_zoneid) != NULL) {
                err = EEXIST;
                goto done;
        }

        (void) strlcpy(oldname, linkp->ll_link, MAXLINKNAMELEN);
        avl_remove(&dlmgmt_name_avl, linkp);
        (void) strlcpy(linkp->ll_link, remapid->ld_link, MAXLINKNAMELEN);
        avl_add(&dlmgmt_name_avl, linkp);
        renamed = B_TRUE;

        if (linkp->ll_flags & DLMGMT_ACTIVE) {
                err = dlmgmt_write_db_entry(oldname, linkp, DLMGMT_ACTIVE);
                if (err != 0)
                        goto done;
        }
        if (linkp->ll_flags & DLMGMT_PERSIST) {
                err = dlmgmt_write_db_entry(oldname, linkp, DLMGMT_PERSIST);
                if (err != 0) {
                        if (linkp->ll_flags & DLMGMT_ACTIVE) {
                                (void) dlmgmt_write_db_entry(remapid->ld_link,
                                    linkp, DLMGMT_ACTIVE);
                        }
                        goto done;
                }
        }

        dlmgmt_advance(linkp);
        linkp->ll_gen++;
done:
        if (err != 0 && renamed) {
                avl_remove(&dlmgmt_name_avl, linkp);
                (void) strlcpy(linkp->ll_link, oldname, MAXLINKNAMELEN);
                avl_add(&dlmgmt_name_avl, linkp);
        }
        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_upid(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_upid_t      *upid = argp;
        dlmgmt_upid_retval_t    *retvalp = retp;
        dlmgmt_link_t           *linkp;
        int                     err = 0;

        /*
         * Hold the writer lock to update the link table.
         */
        dlmgmt_table_lock(B_TRUE);
        if ((linkp = link_by_id(upid->ld_linkid, zoneid)) == NULL) {
                err = ENOENT;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(linkp->ll_class, cred)) != 0)
                goto done;

        if (linkp->ll_flags & DLMGMT_ACTIVE) {
                err = EINVAL;
                goto done;
        }

        if ((err = link_activate(linkp)) == 0) {
                (void) dlmgmt_write_db_entry(linkp->ll_link, linkp,
                    DLMGMT_ACTIVE);
        }
done:
        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_createconf(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_createconf_t *createconf = argp;
        dlmgmt_createconf_retval_t *retvalp = retp;
        dlmgmt_dlconf_t         *dlconfp;
        int                     err;

        /*
         * Hold the writer lock to update the dlconf table.
         */
        dlmgmt_dlconf_table_lock(B_TRUE);

        if ((err = dlmgmt_checkprivs(createconf->ld_class, cred)) != 0)
                goto done;

        err = dlconf_create(createconf->ld_link, createconf->ld_linkid,
            createconf->ld_class, createconf->ld_media, zoneid, &dlconfp);
        if (err == 0) {
                avl_add(&dlmgmt_dlconf_avl, dlconfp);
                dlmgmt_advance_dlconfid(dlconfp);
                retvalp->lr_confid = dlconfp->ld_id;
        }
done:
        dlmgmt_dlconf_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_setattr(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_setattr_t   *setattr = argp;
        dlmgmt_setattr_retval_t *retvalp = retp;
        dlmgmt_dlconf_t         dlconf, *dlconfp;
        int                     err = 0;

        /*
         * Hold the writer lock to update the dlconf table.
         */
        dlmgmt_dlconf_table_lock(B_TRUE);

        dlconf.ld_id = setattr->ld_confid;
        dlconfp = avl_find(&dlmgmt_dlconf_avl, &dlconf, NULL);
        if (dlconfp == NULL || zoneid != dlconfp->ld_zoneid) {
                err = ENOENT;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(dlconfp->ld_class, cred)) != 0)
                goto done;

        err = linkattr_set(&(dlconfp->ld_head), setattr->ld_attr,
            &setattr->ld_attrval, setattr->ld_attrsz, setattr->ld_type);

done:
        dlmgmt_dlconf_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_unsetconfattr(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_unsetattr_t *unsetattr = argp;
        dlmgmt_unsetattr_retval_t *retvalp = retp;
        dlmgmt_dlconf_t         dlconf, *dlconfp;
        int                     err = 0;

        /*
         * Hold the writer lock to update the dlconf table.
         */
        dlmgmt_dlconf_table_lock(B_TRUE);

        dlconf.ld_id = unsetattr->ld_confid;
        dlconfp = avl_find(&dlmgmt_dlconf_avl, &dlconf, NULL);
        if (dlconfp == NULL || zoneid != dlconfp->ld_zoneid) {
                err = ENOENT;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(dlconfp->ld_class, cred)) != 0)
                goto done;

        linkattr_unset(&(dlconfp->ld_head), unsetattr->ld_attr);

done:
        dlmgmt_dlconf_table_unlock();
        retvalp->lr_err = err;
}

/*
 * Note that dlmgmt_openconf() returns a conf ID of a conf AVL tree entry,
 * which is managed by dlmgmtd.  The ID is used to find the conf entry when
 * dlmgmt_write_conf() is called.  The conf entry contains an ld_gen value
 * (which is the generation number - ll_gen) of the dlmgmt_link_t at the time
 * of dlmgmt_openconf(), and ll_gen changes every time the dlmgmt_link_t
 * changes its attributes.  Therefore, dlmgmt_write_conf() can compare ld_gen
 * in the conf entry against the latest dlmgmt_link_t ll_gen value to see if
 * anything has changed between the dlmgmt_openconf() and dlmgmt_writeconf()
 * calls.  If so, EAGAIN is returned.  This mechanism can ensures atomicity
 * across the pair of dladm_read_conf() and dladm_write_conf() calls.
 */
/* ARGSUSED */
static void
dlmgmt_writeconf(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_writeconf_t *writeconf = argp;
        dlmgmt_writeconf_retval_t *retvalp = retp;
        dlmgmt_dlconf_t         dlconf, *dlconfp;
        dlmgmt_link_t           *linkp;
        dlmgmt_linkattr_t       *attrp, *next;
        int                     err = 0;

        /*
         * Hold the lock to access the dlconf table.
         */
        dlmgmt_dlconf_table_lock(B_TRUE);

        dlconf.ld_id = writeconf->ld_confid;
        dlconfp = avl_find(&dlmgmt_dlconf_avl, &dlconf, NULL);
        if (dlconfp == NULL || zoneid != dlconfp->ld_zoneid) {
                err = ENOENT;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(dlconfp->ld_class, cred)) != 0)
                goto done;

        /*
         * Hold the writer lock to update the link table.
         */
        dlmgmt_table_lock(B_TRUE);
        linkp = link_by_id(dlconfp->ld_linkid, zoneid);
        if ((linkp == NULL) || (linkp->ll_class != dlconfp->ld_class) ||
            (linkp->ll_media != dlconfp->ld_media) ||
            (strcmp(linkp->ll_link, dlconfp->ld_link) != 0)) {
                /*
                 * The link does not exist.
                 */
                dlmgmt_table_unlock();
                err = ENOENT;
                goto done;
        }

        if (linkp->ll_gen != dlconfp->ld_gen) {
                /*
                 * Something has changed the link configuration; try again.
                 */
                dlmgmt_table_unlock();
                err = EAGAIN;
                goto done;
        }

        /*
         * Delete the old attribute list.
         */
        for (attrp = linkp->ll_head; attrp != NULL; attrp = next) {
                next = attrp->lp_next;
                free(attrp->lp_val);
                free(attrp);
        }
        linkp->ll_head = NULL;

        /*
         * Set the new attribute.
         */
        for (attrp = dlconfp->ld_head; attrp != NULL; attrp = attrp->lp_next) {
                if ((err = linkattr_set(&(linkp->ll_head), attrp->lp_name,
                    attrp->lp_val, attrp->lp_sz, attrp->lp_type)) != 0) {
                        dlmgmt_table_unlock();
                        goto done;
                }
        }

        linkp->ll_gen++;
        err = dlmgmt_write_db_entry(linkp->ll_link, linkp, DLMGMT_PERSIST);
        dlmgmt_table_unlock();
done:
        dlmgmt_dlconf_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_removeconf(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_removeconf_t        *removeconf = argp;
        dlmgmt_removeconf_retval_t      *retvalp = retp;
        dlmgmt_link_t                   *linkp;
        int                             err;

        dlmgmt_table_lock(B_TRUE);
        if ((linkp = link_by_id(removeconf->ld_linkid, zoneid)) == NULL) {
                err = ENOENT;
                goto done;
        }
        if (zoneid != GLOBAL_ZONEID && linkp->ll_onloan) {
                /*
                 * A non-global zone cannot remove the persistent
                 * configuration of a link that is on loan from the global
                 * zone.
                 */
                err = EACCES;
                goto done;
        }
        if ((err = dlmgmt_checkprivs(linkp->ll_class, cred)) != 0)
                goto done;

        err = dlmgmt_delete_db_entry(linkp, DLMGMT_PERSIST);
done:
        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_destroyconf(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_destroyconf_t       *destroyconf = argp;
        dlmgmt_destroyconf_retval_t     *retvalp = retp;
        dlmgmt_dlconf_t                 dlconf, *dlconfp;
        int                             err = 0;

        /*
         * Hold the writer lock to update the dlconf table.
         */
        dlmgmt_dlconf_table_lock(B_TRUE);

        dlconf.ld_id = destroyconf->ld_confid;
        dlconfp = avl_find(&dlmgmt_dlconf_avl, &dlconf, NULL);
        if (dlconfp == NULL || zoneid != dlconfp->ld_zoneid) {
                err = ENOENT;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(dlconfp->ld_class, cred)) != 0)
                goto done;

        avl_remove(&dlmgmt_dlconf_avl, dlconfp);
        dlconf_destroy(dlconfp);

done:
        dlmgmt_dlconf_table_unlock();
        retvalp->lr_err = err;
}

/*
 * dlmgmt_openconf() returns a handle of the current configuration, which
 * is then used to update the configuration by dlmgmt_writeconf(). Therefore,
 * it requires privileges.
 *
 * Further, please see the comments above dladm_write_conf() to see how
 * ld_gen is used to ensure atomicity across the {dlmgmt_openconf(),
 * dlmgmt_writeconf()} pair.
 */
/* ARGSUSED */
static void
dlmgmt_openconf(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_openconf_t  *openconf = argp;
        dlmgmt_openconf_retval_t *retvalp = retp;
        dlmgmt_link_t           *linkp;
        datalink_id_t           linkid = openconf->ld_linkid;
        dlmgmt_dlconf_t         *dlconfp;
        dlmgmt_linkattr_t       *attrp;
        int                     err = 0;

        /*
         * Hold the writer lock to update the dlconf table.
         */
        dlmgmt_dlconf_table_lock(B_TRUE);

        /*
         * Hold the reader lock to access the link
         */
        dlmgmt_table_lock(B_FALSE);
        linkp = link_by_id(linkid, zoneid);
        if ((linkp == NULL) || !(linkp->ll_flags & DLMGMT_PERSIST)) {
                /* The persistent link configuration does not exist. */
                err = ENOENT;
                goto done;
        }
        if (linkp->ll_onloan && zoneid != GLOBAL_ZONEID) {
                /*
                 * The caller is in a non-global zone and the persistent
                 * configuration belongs to the global zone.
                 */
                err = EACCES;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(linkp->ll_class, cred)) != 0)
                goto done;

        if ((err = dlconf_create(linkp->ll_link, linkp->ll_linkid,
            linkp->ll_class, linkp->ll_media, zoneid, &dlconfp)) != 0)
                goto done;

        for (attrp = linkp->ll_head; attrp != NULL; attrp = attrp->lp_next) {
                if ((err = linkattr_set(&(dlconfp->ld_head), attrp->lp_name,
                    attrp->lp_val, attrp->lp_sz, attrp->lp_type)) != 0) {
                        dlconf_destroy(dlconfp);
                        goto done;
                }
        }
        dlconfp->ld_gen = linkp->ll_gen;
        avl_add(&dlmgmt_dlconf_avl, dlconfp);
        dlmgmt_advance_dlconfid(dlconfp);

        retvalp->lr_confid = dlconfp->ld_id;
done:
        dlmgmt_table_unlock();
        dlmgmt_dlconf_table_unlock();
        retvalp->lr_err = err;
}

/*
 * dlmgmt_getconfsnapshot() returns a read-only snapshot of all the
 * configuration, and requires no privileges.
 *
 * If the given size cannot hold all the configuration, set the size
 * that is needed, and return ENOSPC.
 */
/* ARGSUSED */
static void
dlmgmt_getconfsnapshot(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_getconfsnapshot_t   *snapshot = argp;
        dlmgmt_getconfsnapshot_retval_t *retvalp = retp;
        dlmgmt_link_t                   *linkp;
        datalink_id_t                   linkid = snapshot->ld_linkid;
        dlmgmt_linkattr_t               *attrp;
        char                            *buf;
        size_t                          nvlsz;
        nvlist_t                        *nvl = NULL;
        int                             err = 0;

        assert(*sz >= sizeof (dlmgmt_getconfsnapshot_retval_t));

        /*
         * Hold the reader lock to access the link
         */
        dlmgmt_table_lock(B_FALSE);
        linkp = link_by_id(linkid, zoneid);
        if ((linkp == NULL) || !(linkp->ll_flags & DLMGMT_PERSIST)) {
                /* The persistent link configuration does not exist. */
                err = ENOENT;
                goto done;
        }
        if (linkp->ll_onloan && zoneid != GLOBAL_ZONEID) {
                /*
                 * The caller is in a non-global zone and the persistent
                 * configuration belongs to the global zone.
                 */
                err = EACCES;
                goto done;
        }

        err = nvlist_alloc(&nvl, NV_UNIQUE_NAME_TYPE, 0);
        if (err != 0)
                goto done;

        for (attrp = linkp->ll_head; attrp != NULL; attrp = attrp->lp_next) {
                if ((err = nvlist_add_byte_array(nvl, attrp->lp_name,
                    attrp->lp_val, attrp->lp_sz)) != 0) {
                        goto done;
                }
        }

        if ((err = nvlist_size(nvl, &nvlsz, NV_ENCODE_NATIVE)) != 0)
                goto done;

        if (nvlsz + sizeof (dlmgmt_getconfsnapshot_retval_t) > *sz) {
                *sz = nvlsz + sizeof (dlmgmt_getconfsnapshot_retval_t);
                err = ENOSPC;
                goto done;
        }

        /*
         * pack the the nvlist into the return value.
         */
        *sz = nvlsz + sizeof (dlmgmt_getconfsnapshot_retval_t);
        retvalp->lr_nvlsz = nvlsz;
        buf = (char *)retvalp + sizeof (dlmgmt_getconfsnapshot_retval_t);
        err = nvlist_pack(nvl, &buf, &nvlsz, NV_ENCODE_NATIVE, 0);

done:
        dlmgmt_table_unlock();
        nvlist_free(nvl);
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_getattr(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_getattr_t   *getattr = argp;
        dlmgmt_getattr_retval_t *retvalp = retp;
        dlmgmt_dlconf_t         dlconf, *dlconfp;
        int                     err;

        /*
         * Hold the read lock to access the dlconf table.
         */
        dlmgmt_dlconf_table_lock(B_FALSE);

        dlconf.ld_id = getattr->ld_confid;
        if ((dlconfp = avl_find(&dlmgmt_dlconf_avl, &dlconf, NULL)) == NULL ||
            zoneid != dlconfp->ld_zoneid) {
                retvalp->lr_err = ENOENT;
        } else {
                if ((err = dlmgmt_checkprivs(dlconfp->ld_class, cred)) != 0) {
                        retvalp->lr_err = err;
                } else {
                        retvalp->lr_err = dlmgmt_getattr_common(
                            &dlconfp->ld_head, getattr->ld_attr, retvalp);
                }
        }

        dlmgmt_dlconf_table_unlock();
}

/* ARGSUSED */
static void
dlmgmt_upcall_linkprop_init(void *argp, void *retp, size_t *sz,
    zoneid_t zoneid, ucred_t *cred)
{
        dlmgmt_door_linkprop_init_t     *lip = argp;
        dlmgmt_linkprop_init_retval_t   *retvalp = retp;
        dlmgmt_link_t                   *linkp;
        int                             err;

        dlmgmt_table_lock(B_FALSE);
        if ((linkp = link_by_id(lip->ld_linkid, zoneid)) == NULL)
                err = ENOENT;
        else
                err = dlmgmt_checkprivs(linkp->ll_class, cred);
        dlmgmt_table_unlock();

        if (err == 0) {
                dladm_status_t  s;
                char            buf[DLADM_STRSIZE];

                s = dladm_init_linkprop(dld_handle, lip->ld_linkid, B_TRUE);
                if (s != DLADM_STATUS_OK) {
                        dlmgmt_log(LOG_WARNING,
                            "linkprop initialization failed on link %d: %s",
                            lip->ld_linkid, dladm_status2str(s, buf));
                        err = EINVAL;
                }
        }
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_setzoneid(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        dlmgmt_door_setzoneid_t *setzoneid = argp;
        dlmgmt_setzoneid_retval_t *retvalp = retp;
        dlmgmt_link_t           *linkp;
        datalink_id_t           linkid = setzoneid->ld_linkid;
        zoneid_t                oldzoneid, newzoneid;
        int                     err = 0;

        dlmgmt_table_lock(B_TRUE);

        /* We currently only allow changing zoneid's from the global zone. */
        if (zoneid != GLOBAL_ZONEID) {
                err = EACCES;
                goto done;
        }

        if ((linkp = link_by_id(linkid, zoneid)) == NULL) {
                err = ENOENT;
                goto done;
        }

        if ((err = dlmgmt_checkprivs(linkp->ll_class, cred)) != 0)
                goto done;

        /* We can only assign an active link to a zone. */
        if (!(linkp->ll_flags & DLMGMT_ACTIVE)) {
                err = EINVAL;
                goto done;
        }

        oldzoneid = linkp->ll_zoneid;
        newzoneid = setzoneid->ld_zoneid;

        if (oldzoneid == newzoneid)
                goto done;

        /*
         * Before we remove the link from its current zone, make sure that
         * there isn't a link with the same name in the destination zone.
         */
        if (link_by_name(linkp->ll_link, newzoneid) != NULL) {
                err = EEXIST;
                goto done;
        }

        if (oldzoneid != GLOBAL_ZONEID) {
                if (zone_remove_datalink(oldzoneid, linkid) != 0) {
                        err = errno;
                        dlmgmt_log(LOG_WARNING, "unable to remove link %d from "
                            "zone %d: %s", linkid, oldzoneid, strerror(err));
                        goto done;
                }
                avl_remove(&dlmgmt_loan_avl, linkp);
                linkp->ll_onloan = B_FALSE;
        }
        if (newzoneid != GLOBAL_ZONEID) {
                if (zone_add_datalink(newzoneid, linkid) != 0) {
                        err = errno;
                        dlmgmt_log(LOG_WARNING, "unable to add link %d to zone "
                            "%d: %s", linkid, newzoneid, strerror(err));
                        (void) zone_add_datalink(oldzoneid, linkid);
                        goto done;
                }
                avl_add(&dlmgmt_loan_avl, linkp);
                linkp->ll_onloan = B_TRUE;
        }

        avl_remove(&dlmgmt_name_avl, linkp);
        linkp->ll_zoneid = newzoneid;
        avl_add(&dlmgmt_name_avl, linkp);

done:
        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_zoneboot(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        int                     err;
        dlmgmt_door_zoneboot_t  *zoneboot = argp;
        dlmgmt_zoneboot_retval_t *retvalp = retp;

        dlmgmt_table_lock(B_TRUE);

        if ((err = dlmgmt_checkprivs(0, cred)) != 0)
                goto done;

        if (zoneid != GLOBAL_ZONEID) {
                err = EACCES;
                goto done;
        }
        if (zoneboot->ld_zoneid == GLOBAL_ZONEID) {
                err = EINVAL;
                goto done;
        }

        if ((err = dlmgmt_elevate_privileges()) == 0) {
                err = dlmgmt_zone_init(zoneboot->ld_zoneid);
                (void) dlmgmt_drop_privileges();
        }
done:
        dlmgmt_table_unlock();
        retvalp->lr_err = err;
}

/* ARGSUSED */
static void
dlmgmt_zonehalt(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
    ucred_t *cred)
{
        int                     err = 0;
        dlmgmt_door_zonehalt_t  *zonehalt = argp;
        dlmgmt_zonehalt_retval_t *retvalp = retp;

        if ((err = dlmgmt_checkprivs(0, cred)) == 0) {
                if (zoneid != GLOBAL_ZONEID) {
                        err = EACCES;
                } else if (zonehalt->ld_zoneid == GLOBAL_ZONEID) {
                        err = EINVAL;
                } else {
                        dlmgmt_table_lock(B_TRUE);
                        dlmgmt_db_fini(zonehalt->ld_zoneid);
                        dlmgmt_table_unlock();
                }
        }
        retvalp->lr_err = err;
}

static dlmgmt_door_info_t i_dlmgmt_door_info_tbl[] = {
        { DLMGMT_CMD_DLS_CREATE, sizeof (dlmgmt_upcall_arg_create_t),
            sizeof (dlmgmt_create_retval_t), dlmgmt_upcall_create },
        { DLMGMT_CMD_DLS_GETATTR, sizeof (dlmgmt_upcall_arg_getattr_t),
            sizeof (dlmgmt_getattr_retval_t), dlmgmt_upcall_getattr },
        { DLMGMT_CMD_DLS_DESTROY, sizeof (dlmgmt_upcall_arg_destroy_t),
            sizeof (dlmgmt_destroy_retval_t), dlmgmt_upcall_destroy },
        { DLMGMT_CMD_GETNAME, sizeof (dlmgmt_door_getname_t),
            sizeof (dlmgmt_getname_retval_t), dlmgmt_getname },
        { DLMGMT_CMD_GETLINKID, sizeof (dlmgmt_door_getlinkid_t),
            sizeof (dlmgmt_getlinkid_retval_t), dlmgmt_getlinkid },
        { DLMGMT_CMD_GETNEXT, sizeof (dlmgmt_door_getnext_t),
            sizeof (dlmgmt_getnext_retval_t), dlmgmt_getnext },
        { DLMGMT_CMD_DLS_UPDATE, sizeof (dlmgmt_upcall_arg_update_t),
            sizeof (dlmgmt_update_retval_t), dlmgmt_upcall_update },
        { DLMGMT_CMD_CREATE_LINKID, sizeof (dlmgmt_door_createid_t),
            sizeof (dlmgmt_createid_retval_t), dlmgmt_createid },
        { DLMGMT_CMD_DESTROY_LINKID, sizeof (dlmgmt_door_destroyid_t),
            sizeof (dlmgmt_destroyid_retval_t), dlmgmt_destroyid },
        { DLMGMT_CMD_REMAP_LINKID, sizeof (dlmgmt_door_remapid_t),
            sizeof (dlmgmt_remapid_retval_t), dlmgmt_remapid },
        { DLMGMT_CMD_CREATECONF, sizeof (dlmgmt_door_createconf_t),
            sizeof (dlmgmt_createconf_retval_t), dlmgmt_createconf },
        { DLMGMT_CMD_OPENCONF, sizeof (dlmgmt_door_openconf_t),
            sizeof (dlmgmt_openconf_retval_t), dlmgmt_openconf },
        { DLMGMT_CMD_WRITECONF, sizeof (dlmgmt_door_writeconf_t),
            sizeof (dlmgmt_writeconf_retval_t), dlmgmt_writeconf },
        { DLMGMT_CMD_UP_LINKID, sizeof (dlmgmt_door_upid_t),
            sizeof (dlmgmt_upid_retval_t), dlmgmt_upid },
        { DLMGMT_CMD_SETATTR, sizeof (dlmgmt_door_setattr_t),
            sizeof (dlmgmt_setattr_retval_t), dlmgmt_setattr },
        { DLMGMT_CMD_UNSETATTR, sizeof (dlmgmt_door_unsetattr_t),
            sizeof (dlmgmt_unsetattr_retval_t), dlmgmt_unsetconfattr },
        { DLMGMT_CMD_REMOVECONF, sizeof (dlmgmt_door_removeconf_t),
            sizeof (dlmgmt_removeconf_retval_t), dlmgmt_removeconf },
        { DLMGMT_CMD_DESTROYCONF, sizeof (dlmgmt_door_destroyconf_t),
            sizeof (dlmgmt_destroyconf_retval_t), dlmgmt_destroyconf },
        { DLMGMT_CMD_GETATTR, sizeof (dlmgmt_door_getattr_t),
            sizeof (dlmgmt_getattr_retval_t), dlmgmt_getattr },
        { DLMGMT_CMD_GETCONFSNAPSHOT, sizeof (dlmgmt_door_getconfsnapshot_t),
            sizeof (dlmgmt_getconfsnapshot_retval_t), dlmgmt_getconfsnapshot },
        { DLMGMT_CMD_LINKPROP_INIT, sizeof (dlmgmt_door_linkprop_init_t),
            sizeof (dlmgmt_linkprop_init_retval_t),
            dlmgmt_upcall_linkprop_init },
        { DLMGMT_CMD_SETZONEID, sizeof (dlmgmt_door_setzoneid_t),
            sizeof (dlmgmt_setzoneid_retval_t), dlmgmt_setzoneid },
        { DLMGMT_CMD_ZONEBOOT, sizeof (dlmgmt_door_zoneboot_t),
            sizeof (dlmgmt_zoneboot_retval_t), dlmgmt_zoneboot },
        { DLMGMT_CMD_ZONEHALT, sizeof (dlmgmt_door_zonehalt_t),
            sizeof (dlmgmt_zonehalt_retval_t), dlmgmt_zonehalt },
        { 0, 0, 0, NULL }
};

static dlmgmt_door_info_t *
dlmgmt_getcmdinfo(int cmd)
{
        dlmgmt_door_info_t      *infop = i_dlmgmt_door_info_tbl;

        while (infop->di_handler != NULL) {
                if (infop->di_cmd == cmd)
                        break;
                infop++;
        }
        return (infop);
}

/* ARGSUSED */
void
dlmgmt_handler(void *cookie, char *argp, size_t argsz, door_desc_t *dp,
    uint_t n_desc)
{
        dlmgmt_door_arg_t       *door_arg = (dlmgmt_door_arg_t *)(void *)argp;
        dlmgmt_door_info_t      *infop = NULL;
        dlmgmt_retval_t         retval;
        ucred_t                 *cred = NULL;
        zoneid_t                zoneid;
        void                    *retvalp = NULL;
        size_t                  sz, acksz;
        int                     err = 0;

        infop = dlmgmt_getcmdinfo(door_arg->ld_cmd);
        if (infop == NULL || argsz != infop->di_reqsz) {
                err = EINVAL;
                goto done;
        }

        if (door_ucred(&cred) != 0 || (zoneid = ucred_getzoneid(cred)) == -1) {
                err = errno;
                goto done;
        }

        /*
         * Note that malloc() cannot be used here because door_return
         * never returns, and memory allocated by malloc() would get leaked.
         * Use alloca() instead.
         */
        acksz = infop->di_acksz;

again:
        retvalp = alloca(acksz);
        sz = acksz;
        infop->di_handler(argp, retvalp, &acksz, zoneid, cred);
        if (acksz > sz) {
                /*
                 * If the specified buffer size is not big enough to hold the
                 * return value, reallocate the buffer and try to get the
                 * result one more time.
                 */
                assert(((dlmgmt_retval_t *)retvalp)->lr_err == ENOSPC);
                goto again;
        }

done:
        if (cred != NULL)
                ucred_free(cred);
        if (err == 0) {
                (void) door_return(retvalp, acksz, NULL, 0);
        } else {
                retval.lr_err = err;
                (void) door_return((char *)&retval, sizeof (retval), NULL, 0);
        }
}