xnu-4903.270.47.tar.gz

[apple/xnu.git] / bsd / nfs / nfs_syscalls.c

/*
 * Copyright (c) 2000-2016 Apple Inc.  All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Rick Macklem at The University of Guelph.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 *
 *      @(#)nfs_syscalls.c      8.5 (Berkeley) 3/30/95
 * FreeBSD-Id: nfs_syscalls.c,v 1.32 1997/11/07 08:53:25 phk Exp $
 */
/*
 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/file_internal.h>
#include <sys/filedesc.h>
#include <sys/stat.h>
#include <sys/vnode_internal.h>
#include <sys/mount_internal.h>
#include <sys/proc_internal.h> /* for fdflags */
#include <sys/kauth.h>
#include <sys/sysctl.h>
#include <sys/ubc.h>
#include <sys/uio.h>
#include <sys/malloc.h>
#include <sys/kpi_mbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/fcntl.h>
#include <sys/lockf.h>
#include <sys/syslog.h>
#include <sys/user.h>
#include <sys/sysproto.h>
#include <sys/kpi_socket.h>
#include <sys/fsevents.h>
#include <libkern/OSAtomic.h>
#include <kern/thread_call.h>
#include <kern/task.h>

#include <security/audit/audit.h>

#include <netinet/in.h>
#include <netinet/tcp.h>
#include <nfs/xdr_subs.h>
#include <nfs/rpcv2.h>
#include <nfs/nfsproto.h>
#include <nfs/nfs.h>
#include <nfs/nfsm_subs.h>
#include <nfs/nfsrvcache.h>
#include <nfs/nfs_gss.h>
#include <nfs/nfsmount.h>
#include <nfs/nfsnode.h>
#include <nfs/nfs_lock.h>
#if CONFIG_MACF
#include <security/mac_framework.h>
#endif

kern_return_t   thread_terminate(thread_t); /* XXX */

#if NFSSERVER

extern const nfsrv_proc_t nfsrv_procs[NFS_NPROCS];

extern int nfsrv_wg_delay;
extern int nfsrv_wg_delay_v3;

static int nfsrv_require_resv_port = 0;
static time_t  nfsrv_idlesock_timer_on = 0;
static int nfsrv_sock_tcp_cnt = 0;
#define NFSD_MIN_IDLE_TIMEOUT 30
static int nfsrv_sock_idle_timeout = 3600; /* One hour */

int     nfssvc_export(user_addr_t argp);
int     nfssvc_nfsd(void);
int     nfssvc_addsock(socket_t, mbuf_t);
void    nfsrv_zapsock(struct nfsrv_sock *);
void    nfsrv_slpderef(struct nfsrv_sock *);
void    nfsrv_slpfree(struct nfsrv_sock *);

#endif /* NFSSERVER */

/*
 * sysctl stuff
 */
SYSCTL_DECL(_vfs_generic);
SYSCTL_NODE(_vfs_generic, OID_AUTO, nfs, CTLFLAG_RW | CTLFLAG_LOCKED, 0, "nfs hinge");

#if NFSCLIENT
SYSCTL_NODE(_vfs_generic_nfs, OID_AUTO, client, CTLFLAG_RW | CTLFLAG_LOCKED, 0, "nfs client hinge");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, initialdowndelay, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_tprintf_initial_delay, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, nextdowndelay, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_tprintf_delay, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, iosize, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_iosize, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, access_cache_timeout, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_access_cache_timeout, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, allow_async, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_allow_async, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, statfs_rate_limit, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_statfs_rate_limit, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, nfsiod_thread_max, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsiod_thread_max, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, nfsiod_thread_count, CTLFLAG_RD | CTLFLAG_LOCKED, &nfsiod_thread_count, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, lockd_mounts, CTLFLAG_RD | CTLFLAG_LOCKED, &nfs_lockd_mounts, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, max_async_writes, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_max_async_writes, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, access_delete, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_access_delete, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, access_dotzfs, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_access_dotzfs, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, access_for_getattr, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_access_for_getattr, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, idmap_ctrl, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_idmap_ctrl, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, callback_port, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_callback_port, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, is_mobile, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_is_mobile, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, squishy_flags, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_squishy_flags, 0, "");
SYSCTL_UINT(_vfs_generic_nfs_client, OID_AUTO, debug_ctl, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_debug_ctl, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, readlink_nocache, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_readlink_nocache, 0, "");
SYSCTL_INT(_vfs_generic_nfs_client, OID_AUTO, root_steals_gss_context, CTLFLAG_RW | CTLFLAG_LOCKED, &nfs_root_steals_ctx, 0, "");
SYSCTL_STRING(_vfs_generic_nfs_client, OID_AUTO, default_nfs4domain, CTLFLAG_RW | CTLFLAG_LOCKED, nfs4_default_domain, sizeof(nfs4_default_domain), "");
#endif /* NFSCLIENT */

#if NFSSERVER
SYSCTL_NODE(_vfs_generic_nfs, OID_AUTO, server, CTLFLAG_RW | CTLFLAG_LOCKED, 0, "nfs server hinge");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, wg_delay, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_wg_delay, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, wg_delay_v3, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_wg_delay_v3, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, require_resv_port, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_require_resv_port, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, async, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_async, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, export_hash_size, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_export_hash_size, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, reqcache_size, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_reqcache_size, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, request_queue_length, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_sock_max_rec_queue_length, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, user_stats, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_user_stat_enabled, 0, "");
SYSCTL_UINT(_vfs_generic_nfs_server, OID_AUTO, gss_context_ttl, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_gss_context_ttl, 0, "");
#if CONFIG_FSE
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, fsevents, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_fsevents_enabled, 0, "");
#endif
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, nfsd_thread_max, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsd_thread_max, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, nfsd_thread_count, CTLFLAG_RD | CTLFLAG_LOCKED, &nfsd_thread_count, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, nfsd_sock_idle_timeout, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_sock_idle_timeout, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, nfsd_tcp_connections, CTLFLAG_RD | CTLFLAG_LOCKED, &nfsrv_sock_tcp_cnt, 0, "");
#ifdef NFS_UC_Q_DEBUG
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, use_upcall_svc, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_uc_use_proxy, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, upcall_queue_limit, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_uc_queue_limit, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, upcall_queue_max_seen, CTLFLAG_RW | CTLFLAG_LOCKED, &nfsrv_uc_queue_max_seen, 0, "");
SYSCTL_INT(_vfs_generic_nfs_server, OID_AUTO, upcall_queue_count, CTLFLAG_RD | CTLFLAG_LOCKED, __DECONST(int *, &nfsrv_uc_queue_count), 0, "");
#endif
#endif /* NFSSERVER */


#if NFSCLIENT

static int
mapname2id(struct nfs_testmapid *map)
{
        int error;

        error = nfs4_id2guid(map->ntm_name, &map->ntm_guid, map->ntm_grpflag);
        if (error) {
                return error;
        }

        if (map->ntm_grpflag) {
                error = kauth_cred_guid2gid(&map->ntm_guid, (gid_t *)&map->ntm_id);
        } else {
                error = kauth_cred_guid2uid(&map->ntm_guid, (uid_t *)&map->ntm_id);
        }

        return error;
}

static int
mapid2name(struct nfs_testmapid *map)
{
        int error;
        size_t len = sizeof(map->ntm_name);

        if (map->ntm_grpflag) {
                error = kauth_cred_gid2guid((gid_t)map->ntm_id, &map->ntm_guid);
        } else {
                error = kauth_cred_uid2guid((uid_t)map->ntm_id, &map->ntm_guid);
        }

        if (error) {
                return error;
        }

        error = nfs4_guid2id(&map->ntm_guid, map->ntm_name, &len, map->ntm_grpflag);

        return error;
}

static int
nfsclnt_testidmap(proc_t p, user_addr_t argp)
{
        struct nfs_testmapid mapid;
        int error, coerror;
        size_t len = sizeof(mapid.ntm_name);

        /* Let root make this call. */
        error = proc_suser(p);
        if (error) {
                return error;
        }

        error = copyin(argp, &mapid, sizeof(mapid));
        if (error) {
                return error;
        }
        switch (mapid.ntm_lookup) {
        case NTM_NAME2ID:
                error = mapname2id(&mapid);
                break;
        case NTM_ID2NAME:
                error = mapid2name(&mapid);
                break;
        case NTM_NAME2GUID:
                error = nfs4_id2guid(mapid.ntm_name, &mapid.ntm_guid, mapid.ntm_grpflag);
                break;
        case NTM_GUID2NAME:
                error = nfs4_guid2id(&mapid.ntm_guid, mapid.ntm_name, &len, mapid.ntm_grpflag);
                break;
        default:
                return EINVAL;
        }

        coerror = copyout(&mapid, argp, sizeof(mapid));

        return error ? error : coerror;
}

int
nfsclnt(proc_t p, struct nfsclnt_args *uap, __unused int *retval)
{
        struct lockd_ans la;
        int error;

        switch (uap->flag) {
        case NFSCLNT_LOCKDANS:
                error = copyin(uap->argp, &la, sizeof(la));
                if (!error) {
                        error = nfslockdans(p, &la);
                }
                break;
        case NFSCLNT_LOCKDNOTIFY:
                error = nfslockdnotify(p, uap->argp);
                break;
        case NFSCLNT_TESTIDMAP:
                error = nfsclnt_testidmap(p, uap->argp);
                break;
        default:
                error = EINVAL;
        }
        return error;
}


/*
 * Asynchronous I/O threads for client NFS.
 * They do read-ahead and write-behind operations on the block I/O cache.
 *
 * The pool of up to nfsiod_thread_max threads is launched on demand and exit
 * when unused for a while.  There are as many nfsiod structs as there are
 * nfsiod threads; however there's no strict tie between a thread and a struct.
 * Each thread puts an nfsiod on the free list and sleeps on it.  When it wakes
 * up, it removes the next struct nfsiod from the queue and services it.  Then
 * it will put the struct at the head of free list and sleep on it.
 * Async requests will pull the next struct nfsiod from the head of the free list,
 * put it on the work queue, and wake whatever thread is waiting on that struct.
 */

/*
 * nfsiod thread exit routine
 *
 * Must be called with nfsiod_mutex held so that the
 * decision to terminate is atomic with the termination.
 */
void
nfsiod_terminate(struct nfsiod *niod)
{
        nfsiod_thread_count--;
        lck_mtx_unlock(nfsiod_mutex);
        if (niod) {
                FREE(niod, M_TEMP);
        } else {
                printf("nfsiod: terminating without niod\n");
        }
        thread_terminate(current_thread());
        /*NOTREACHED*/
}

/* nfsiod thread startup routine */
void
nfsiod_thread(void)
{
        struct nfsiod *niod;
        int error;

        MALLOC(niod, struct nfsiod *, sizeof(struct nfsiod), M_TEMP, M_WAITOK);
        if (!niod) {
                lck_mtx_lock(nfsiod_mutex);
                nfsiod_thread_count--;
                wakeup(current_thread());
                lck_mtx_unlock(nfsiod_mutex);
                thread_terminate(current_thread());
                /*NOTREACHED*/
        }
        bzero(niod, sizeof(*niod));
        lck_mtx_lock(nfsiod_mutex);
        TAILQ_INSERT_HEAD(&nfsiodfree, niod, niod_link);
        wakeup(current_thread());
        error = msleep0(niod, nfsiod_mutex, PWAIT | PDROP, "nfsiod", NFS_ASYNCTHREADMAXIDLE * hz, nfsiod_continue);
        /* shouldn't return... so we have an error */
        /* remove an old nfsiod struct and terminate */
        lck_mtx_lock(nfsiod_mutex);
        if ((niod = TAILQ_LAST(&nfsiodfree, nfsiodlist))) {
                TAILQ_REMOVE(&nfsiodfree, niod, niod_link);
        }
        nfsiod_terminate(niod);
        /*NOTREACHED*/
}

/*
 * Start up another nfsiod thread.
 * (unless we're already maxed out and there are nfsiods running)
 */
int
nfsiod_start(void)
{
        thread_t thd = THREAD_NULL;

        lck_mtx_lock(nfsiod_mutex);
        if ((nfsiod_thread_count >= NFSIOD_MAX) && (nfsiod_thread_count > 0)) {
                lck_mtx_unlock(nfsiod_mutex);
                return EBUSY;
        }
        nfsiod_thread_count++;
        if (kernel_thread_start((thread_continue_t)nfsiod_thread, NULL, &thd) != KERN_SUCCESS) {
                lck_mtx_unlock(nfsiod_mutex);
                return EBUSY;
        }
        /* wait for the thread to complete startup */
        msleep(thd, nfsiod_mutex, PWAIT | PDROP, "nfsiodw", NULL);
        thread_deallocate(thd);
        return 0;
}

/*
 * Continuation for Asynchronous I/O threads for NFS client.
 *
 * Grab an nfsiod struct to work on, do some work, then drop it
 */
int
nfsiod_continue(int error)
{
        struct nfsiod *niod;
        struct nfsmount *nmp;
        struct nfsreq *req, *treq;
        struct nfs_reqqhead iodq;
        int morework;

        lck_mtx_lock(nfsiod_mutex);
        niod = TAILQ_FIRST(&nfsiodwork);
        if (!niod) {
                /* there's no work queued up */
                /* remove an old nfsiod struct and terminate */
                if ((niod = TAILQ_LAST(&nfsiodfree, nfsiodlist))) {
                        TAILQ_REMOVE(&nfsiodfree, niod, niod_link);
                }
                nfsiod_terminate(niod);
                /*NOTREACHED*/
        }
        TAILQ_REMOVE(&nfsiodwork, niod, niod_link);

worktodo:
        while ((nmp = niod->niod_nmp)) {
                if (nmp == NULL) {
                        niod->niod_nmp = NULL;
                        break;
                }

                /*
                 * Service this mount's async I/O queue.
                 *
                 * In order to ensure some level of fairness between mounts,
                 * we grab all the work up front before processing it so any
                 * new work that arrives will be serviced on a subsequent
                 * iteration - and we have a chance to see if other work needs
                 * to be done (e.g. the delayed write queue needs to be pushed
                 * or other mounts are waiting for an nfsiod).
                 */
                /* grab the current contents of the queue */
                TAILQ_INIT(&iodq);
                TAILQ_CONCAT(&iodq, &nmp->nm_iodq, r_achain);
                /* Mark each iod request as being managed by an iod */
                TAILQ_FOREACH(req, &iodq, r_achain) {
                        lck_mtx_lock(&req->r_mtx);
                        assert(!(req->r_flags & R_IOD));
                        req->r_flags |= R_IOD;
                        lck_mtx_unlock(&req->r_mtx);
                }
                lck_mtx_unlock(nfsiod_mutex);

                /* process the queue */
                TAILQ_FOREACH_SAFE(req, &iodq, r_achain, treq) {
                        TAILQ_REMOVE(&iodq, req, r_achain);
                        req->r_achain.tqe_next = NFSREQNOLIST;
                        req->r_callback.rcb_func(req);
                }

                /* now check if there's more/other work to be done */
                lck_mtx_lock(nfsiod_mutex);
                morework = !TAILQ_EMPTY(&nmp->nm_iodq);
                if (!morework || !TAILQ_EMPTY(&nfsiodmounts)) {
                        /*
                         * we're going to stop working on this mount but if the
                         * mount still needs more work so queue it up
                         */
                        if (morework && nmp->nm_iodlink.tqe_next == NFSNOLIST) {
                                TAILQ_INSERT_TAIL(&nfsiodmounts, nmp, nm_iodlink);
                        }
                        nmp->nm_niod = NULL;
                        niod->niod_nmp = NULL;
                }
        }

        /* loop if there's still a mount to work on */
        if (!niod->niod_nmp && !TAILQ_EMPTY(&nfsiodmounts)) {
                niod->niod_nmp = TAILQ_FIRST(&nfsiodmounts);
                TAILQ_REMOVE(&nfsiodmounts, niod->niod_nmp, nm_iodlink);
                niod->niod_nmp->nm_iodlink.tqe_next = NFSNOLIST;
        }
        if (niod->niod_nmp) {
                goto worktodo;
        }

        /* queue ourselves back up - if there aren't too many threads running */
        if (nfsiod_thread_count <= NFSIOD_MAX) {
                TAILQ_INSERT_HEAD(&nfsiodfree, niod, niod_link);
                error = msleep0(niod, nfsiod_mutex, PWAIT | PDROP, "nfsiod", NFS_ASYNCTHREADMAXIDLE * hz, nfsiod_continue);
                /* shouldn't return... so we have an error */
                /* remove an old nfsiod struct and terminate */
                lck_mtx_lock(nfsiod_mutex);
                if ((niod = TAILQ_LAST(&nfsiodfree, nfsiodlist))) {
                        TAILQ_REMOVE(&nfsiodfree, niod, niod_link);
                }
        }
        nfsiod_terminate(niod);
        /*NOTREACHED*/
        return 0;
}

#endif /* NFSCLIENT */


#if NFSSERVER

/*
 * NFS server system calls
 * getfh() lives here too, but maybe should move to kern/vfs_syscalls.c
 */

/*
 * Get file handle system call
 */
int
getfh(proc_t p, struct getfh_args *uap, __unused int *retval)
{
        vnode_t vp;
        struct nfs_filehandle nfh;
        int error, fhlen, fidlen;
        struct nameidata nd;
        char path[MAXPATHLEN], *ptr;
        size_t pathlen;
        struct nfs_exportfs *nxfs;
        struct nfs_export *nx;

        /*
         * Must be super user
         */
        error = proc_suser(p);
        if (error) {
                return error;
        }

        error = copyinstr(uap->fname, path, MAXPATHLEN, &pathlen);
        if (!error) {
                error = copyin(uap->fhp, &fhlen, sizeof(fhlen));
        }
        if (error) {
                return error;
        }
        /* limit fh size to length specified (or v3 size by default) */
        if ((fhlen != NFSV2_MAX_FH_SIZE) && (fhlen != NFSV3_MAX_FH_SIZE)) {
                fhlen = NFSV3_MAX_FH_SIZE;
        }
        fidlen = fhlen - sizeof(struct nfs_exphandle);

        if (!nfsrv_is_initialized()) {
                return EINVAL;
        }

        NDINIT(&nd, LOOKUP, OP_LOOKUP, FOLLOW | LOCKLEAF | AUDITVNPATH1,
            UIO_SYSSPACE, CAST_USER_ADDR_T(path), vfs_context_current());
        error = namei(&nd);
        if (error) {
                return error;
        }
        nameidone(&nd);

        vp = nd.ni_vp;

        // find exportfs that matches f_mntonname
        lck_rw_lock_shared(&nfsrv_export_rwlock);
        ptr = vnode_mount(vp)->mnt_vfsstat.f_mntonname;
        LIST_FOREACH(nxfs, &nfsrv_exports, nxfs_next) {
                if (!strncmp(nxfs->nxfs_path, ptr, MAXPATHLEN)) {
                        break;
                }
        }
        if (!nxfs || strncmp(nxfs->nxfs_path, path, strlen(nxfs->nxfs_path))) {
                error = EINVAL;
                goto out;
        }
        // find export that best matches remainder of path
        ptr = path + strlen(nxfs->nxfs_path);
        while (*ptr && (*ptr == '/')) {
                ptr++;
        }
        LIST_FOREACH(nx, &nxfs->nxfs_exports, nx_next) {
                int len = strlen(nx->nx_path);
                if (len == 0) { // we've hit the export entry for the root directory
                        break;
                }
                if (!strncmp(nx->nx_path, ptr, len)) {
                        break;
                }
        }
        if (!nx) {
                error = EINVAL;
                goto out;
        }

        bzero(&nfh, sizeof(nfh));
        nfh.nfh_xh.nxh_version = htonl(NFS_FH_VERSION);
        nfh.nfh_xh.nxh_fsid = htonl(nxfs->nxfs_id);
        nfh.nfh_xh.nxh_expid = htonl(nx->nx_id);
        nfh.nfh_xh.nxh_flags = 0;
        nfh.nfh_xh.nxh_reserved = 0;
        nfh.nfh_len = fidlen;
        error = VFS_VPTOFH(vp, (int*)&nfh.nfh_len, &nfh.nfh_fid[0], NULL);
        if (nfh.nfh_len > (uint32_t)fidlen) {
                error = EOVERFLOW;
        }
        nfh.nfh_xh.nxh_fidlen = nfh.nfh_len;
        nfh.nfh_len += sizeof(nfh.nfh_xh);
        nfh.nfh_fhp = (u_char*)&nfh.nfh_xh;

out:
        lck_rw_done(&nfsrv_export_rwlock);
        vnode_put(vp);
        if (error) {
                return error;
        }
        /*
         * At first blush, this may appear to leak a kernel stack
         * address, but the copyout() never reaches &nfh.nfh_fhp
         * (sizeof(fhandle_t) < sizeof(nfh)).
         */
        error = copyout((caddr_t)&nfh, uap->fhp, sizeof(fhandle_t));
        return error;
}

extern const struct fileops vnops;

/*
 * syscall for the rpc.lockd to use to translate a NFS file handle into
 * an open descriptor.
 *
 * warning: do not remove the suser() call or this becomes one giant
 * security hole.
 */
int
fhopen( proc_t p,
    struct fhopen_args *uap,
    int32_t *retval)
{
        vnode_t vp;
        struct nfs_filehandle nfh;
        struct nfs_export *nx;
        struct nfs_export_options *nxo;
        struct flock lf;
        struct fileproc *fp, *nfp;
        int fmode, error, type;
        int indx;
        vfs_context_t ctx = vfs_context_current();
        kauth_action_t action;

        /*
         * Must be super user
         */
        error = suser(vfs_context_ucred(ctx), 0);
        if (error) {
                return error;
        }

        if (!nfsrv_is_initialized()) {
                return EINVAL;
        }

        fmode = FFLAGS(uap->flags);
        /* why not allow a non-read/write open for our lockd? */
        if (((fmode & (FREAD | FWRITE)) == 0) || (fmode & O_CREAT)) {
                return EINVAL;
        }

        error = copyin(uap->u_fhp, &nfh.nfh_len, sizeof(nfh.nfh_len));
        if (error) {
                return error;
        }
        if ((nfh.nfh_len < (int)sizeof(struct nfs_exphandle)) ||
            (nfh.nfh_len > (int)NFSV3_MAX_FH_SIZE)) {
                return EINVAL;
        }
        error = copyin(uap->u_fhp, &nfh, sizeof(nfh.nfh_len) + nfh.nfh_len);
        if (error) {
                return error;
        }
        nfh.nfh_fhp = (u_char*)&nfh.nfh_xh;

        lck_rw_lock_shared(&nfsrv_export_rwlock);
        /* now give me my vnode, it gets returned to me with a reference */
        error = nfsrv_fhtovp(&nfh, NULL, &vp, &nx, &nxo);
        lck_rw_done(&nfsrv_export_rwlock);
        if (error) {
                if (error == NFSERR_TRYLATER) {
                        error = EAGAIN; // XXX EBUSY? Or just leave as TRYLATER?
                }
                return error;
        }

        /*
         * From now on we have to make sure not
         * to forget about the vnode.
         * Any error that causes an abort must vnode_put(vp).
         * Just set error = err and 'goto bad;'.
         */

        /*
         * from vn_open
         */
        if (vnode_vtype(vp) == VSOCK) {
                error = EOPNOTSUPP;
                goto bad;
        }

        /* disallow write operations on directories */
        if (vnode_isdir(vp) && (fmode & (FWRITE | O_TRUNC))) {
                error = EISDIR;
                goto bad;
        }

#if CONFIG_MACF
        if ((error = mac_vnode_check_open(ctx, vp, fmode))) {
                goto bad;
        }
#endif

        /* compute action to be authorized */
        action = 0;
        if (fmode & FREAD) {
                action |= KAUTH_VNODE_READ_DATA;
        }
        if (fmode & (FWRITE | O_TRUNC)) {
                action |= KAUTH_VNODE_WRITE_DATA;
        }
        if ((error = vnode_authorize(vp, NULL, action, ctx)) != 0) {
                goto bad;
        }

        if ((error = VNOP_OPEN(vp, fmode, ctx))) {
                goto bad;
        }
        if ((error = vnode_ref_ext(vp, fmode, 0))) {
                goto bad;
        }

        /*
         * end of vn_open code
         */

        // starting here... error paths should call vn_close/vnode_put
        if ((error = falloc(p, &nfp, &indx, ctx)) != 0) {
                vn_close(vp, fmode & FMASK, ctx);
                goto bad;
        }
        fp = nfp;

        fp->f_fglob->fg_flag = fmode & FMASK;
        fp->f_fglob->fg_ops = &vnops;
        fp->f_fglob->fg_data = (caddr_t)vp;

        // XXX do we really need to support this with fhopen()?
        if (fmode & (O_EXLOCK | O_SHLOCK)) {
                lf.l_whence = SEEK_SET;
                lf.l_start = 0;
                lf.l_len = 0;
                if (fmode & O_EXLOCK) {
                        lf.l_type = F_WRLCK;
                } else {
                        lf.l_type = F_RDLCK;
                }
                type = F_FLOCK;
                if ((fmode & FNONBLOCK) == 0) {
                        type |= F_WAIT;
                }
                if ((error = VNOP_ADVLOCK(vp, (caddr_t)fp->f_fglob, F_SETLK, &lf, type, ctx, NULL))) {
                        struct vfs_context context = *vfs_context_current();
                        /* Modify local copy (to not damage thread copy) */
                        context.vc_ucred = fp->f_fglob->fg_cred;

                        vn_close(vp, fp->f_fglob->fg_flag, &context);
                        fp_free(p, indx, fp);
                        return error;
                }
                fp->f_fglob->fg_flag |= FHASLOCK;
        }

        vnode_put(vp);

        proc_fdlock(p);
        procfdtbl_releasefd(p, indx, NULL);
        fp_drop(p, indx, fp, 1);
        proc_fdunlock(p);

        *retval = indx;
        return 0;

bad:
        vnode_put(vp);
        return error;
}

/*
 * NFS server pseudo system call
 */
int
nfssvc(proc_t p, struct nfssvc_args *uap, __unused int *retval)
{
        mbuf_t nam;
        struct user_nfsd_args user_nfsdarg;
        socket_t so;
        int error;

        AUDIT_ARG(cmd, uap->flag);

        /*
         * Must be super user for most operations (export ops checked later).
         */
        if ((uap->flag != NFSSVC_EXPORT) && ((error = proc_suser(p)))) {
                return error;
        }
#if CONFIG_MACF
        error = mac_system_check_nfsd(kauth_cred_get());
        if (error) {
                return error;
        }
#endif

        /* make sure NFS server data structures have been initialized */
        nfsrv_init();

        if (uap->flag & NFSSVC_ADDSOCK) {
                if (IS_64BIT_PROCESS(p)) {
                        error = copyin(uap->argp, (caddr_t)&user_nfsdarg, sizeof(user_nfsdarg));
                } else {
                        struct nfsd_args    tmp_args;
                        error = copyin(uap->argp, (caddr_t)&tmp_args, sizeof(tmp_args));
                        if (error == 0) {
                                user_nfsdarg.sock = tmp_args.sock;
                                user_nfsdarg.name = CAST_USER_ADDR_T(tmp_args.name);
                                user_nfsdarg.namelen = tmp_args.namelen;
                        }
                }
                if (error) {
                        return error;
                }
                /* get the socket */
                error = file_socket(user_nfsdarg.sock, &so);
                if (error) {
                        return error;
                }
                /* Get the client address for connected sockets. */
                if (user_nfsdarg.name == USER_ADDR_NULL || user_nfsdarg.namelen == 0) {
                        nam = NULL;
                } else {
                        error = sockargs(&nam, user_nfsdarg.name, user_nfsdarg.namelen, MBUF_TYPE_SONAME);
                        if (error) {
                                /* drop the iocount file_socket() grabbed on the file descriptor */
                                file_drop(user_nfsdarg.sock);
                                return error;
                        }
                }
                /*
                 * nfssvc_addsock() will grab a retain count on the socket
                 * to keep the socket from being closed when nfsd closes its
                 * file descriptor for it.
                 */
                error = nfssvc_addsock(so, nam);
                /* drop the iocount file_socket() grabbed on the file descriptor */
                file_drop(user_nfsdarg.sock);
        } else if (uap->flag & NFSSVC_NFSD) {
                error = nfssvc_nfsd();
        } else if (uap->flag & NFSSVC_EXPORT) {
                error = nfssvc_export(uap->argp);
        } else {
                error = EINVAL;
        }
        if (error == EINTR || error == ERESTART) {
                error = 0;
        }
        return error;
}

/*
 * Adds a socket to the list for servicing by nfsds.
 */
int
nfssvc_addsock(socket_t so, mbuf_t mynam)
{
        struct nfsrv_sock *slp;
        int error = 0, sodomain, sotype, soprotocol, on = 1;
        int first;
        struct timeval timeo;

        /* make sure mbuf constants are set up */
        if (!nfs_mbuf_mhlen) {
                nfs_mbuf_init();
        }

        sock_gettype(so, &sodomain, &sotype, &soprotocol);

        /* There should be only one UDP socket for each of IPv4 and IPv6 */
        if ((sodomain == AF_INET) && (soprotocol == IPPROTO_UDP) && nfsrv_udpsock) {
                mbuf_freem(mynam);
                return EEXIST;
        }
        if ((sodomain == AF_INET6) && (soprotocol == IPPROTO_UDP) && nfsrv_udp6sock) {
                mbuf_freem(mynam);
                return EEXIST;
        }

        /* Set protocol options and reserve some space (for UDP). */
        if (sotype == SOCK_STREAM) {
                error = nfsrv_check_exports_allow_address(mynam);
                if (error) {
                        return error;
                }
                sock_setsockopt(so, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on));
        }
        if ((sodomain == AF_INET) && (soprotocol == IPPROTO_TCP)) {
                sock_setsockopt(so, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
        }
        if (sotype == SOCK_DGRAM) { /* set socket buffer sizes for UDP */
                int reserve = NFS_UDPSOCKBUF;
                error |= sock_setsockopt(so, SOL_SOCKET, SO_SNDBUF, &reserve, sizeof(reserve));
                error |= sock_setsockopt(so, SOL_SOCKET, SO_RCVBUF, &reserve, sizeof(reserve));
                if (error) {
                        log(LOG_INFO, "nfssvc_addsock: UDP socket buffer setting error(s) %d\n", error);
                        error = 0;
                }
        }
        sock_nointerrupt(so, 0);

        /*
         * Set socket send/receive timeouts.
         * Receive timeout shouldn't matter, but setting the send timeout
         * will make sure that an unresponsive client can't hang the server.
         */
        timeo.tv_usec = 0;
        timeo.tv_sec = 1;
        error |= sock_setsockopt(so, SOL_SOCKET, SO_RCVTIMEO, &timeo, sizeof(timeo));
        timeo.tv_sec = 30;
        error |= sock_setsockopt(so, SOL_SOCKET, SO_SNDTIMEO, &timeo, sizeof(timeo));
        if (error) {
                log(LOG_INFO, "nfssvc_addsock: socket timeout setting error(s) %d\n", error);
                error = 0;
        }

        MALLOC(slp, struct nfsrv_sock *, sizeof(struct nfsrv_sock), M_NFSSVC, M_WAITOK);
        if (!slp) {
                mbuf_freem(mynam);
                return ENOMEM;
        }
        bzero((caddr_t)slp, sizeof(struct nfsrv_sock));
        lck_rw_init(&slp->ns_rwlock, nfsrv_slp_rwlock_group, LCK_ATTR_NULL);
        lck_mtx_init(&slp->ns_wgmutex, nfsrv_slp_mutex_group, LCK_ATTR_NULL);

        lck_mtx_lock(nfsd_mutex);

        if (soprotocol == IPPROTO_UDP) {
                if (sodomain == AF_INET) {
                        /* There should be only one UDP/IPv4 socket */
                        if (nfsrv_udpsock) {
                                lck_mtx_unlock(nfsd_mutex);
                                nfsrv_slpfree(slp);
                                mbuf_freem(mynam);
                                return EEXIST;
                        }
                        nfsrv_udpsock = slp;
                }
                if (sodomain == AF_INET6) {
                        /* There should be only one UDP/IPv6 socket */
                        if (nfsrv_udp6sock) {
                                lck_mtx_unlock(nfsd_mutex);
                                nfsrv_slpfree(slp);
                                mbuf_freem(mynam);
                                return EEXIST;
                        }
                        nfsrv_udp6sock = slp;
                }
        }

        /* add the socket to the list */
        first = TAILQ_EMPTY(&nfsrv_socklist);
        TAILQ_INSERT_TAIL(&nfsrv_socklist, slp, ns_chain);
        if (soprotocol == IPPROTO_TCP) {
                nfsrv_sock_tcp_cnt++;
                if (nfsrv_sock_idle_timeout < 0) {
                        nfsrv_sock_idle_timeout = 0;
                }
                if (nfsrv_sock_idle_timeout && (nfsrv_sock_idle_timeout < NFSD_MIN_IDLE_TIMEOUT)) {
                        nfsrv_sock_idle_timeout = NFSD_MIN_IDLE_TIMEOUT;
                }
                /*
                 * Possibly start or stop the idle timer. We only start the idle timer when
                 * we have more than 2 * nfsd_thread_max connections. If the idle timer is
                 * on then we may need to turn it off based on the nvsrv_sock_idle_timeout or
                 * the number of connections.
                 */
                if ((nfsrv_sock_tcp_cnt > 2 * nfsd_thread_max) || nfsrv_idlesock_timer_on) {
                        if (nfsrv_sock_idle_timeout == 0 || nfsrv_sock_tcp_cnt <= 2 * nfsd_thread_max) {
                                if (nfsrv_idlesock_timer_on) {
                                        thread_call_cancel(nfsrv_idlesock_timer_call);
                                        nfsrv_idlesock_timer_on = 0;
                                }
                        } else {
                                struct nfsrv_sock *old_slp;
                                struct timeval now;
                                time_t time_to_wait = nfsrv_sock_idle_timeout;
                                /*
                                 * Get the oldest tcp socket and calculate the
                                 * earliest time for the next idle timer to fire
                                 * based on the possibly updated nfsrv_sock_idle_timeout
                                 */
                                TAILQ_FOREACH(old_slp, &nfsrv_socklist, ns_chain) {
                                        if (old_slp->ns_sotype == SOCK_STREAM) {
                                                microuptime(&now);
                                                time_to_wait -= now.tv_sec - old_slp->ns_timestamp;
                                                if (time_to_wait < 1) {
                                                        time_to_wait = 1;
                                                }
                                                break;
                                        }
                                }
                                /*
                                 * If we have a timer scheduled, but if its going to fire too late,
                                 * turn it off.
                                 */
                                if (nfsrv_idlesock_timer_on > now.tv_sec + time_to_wait) {
                                        thread_call_cancel(nfsrv_idlesock_timer_call);
                                        nfsrv_idlesock_timer_on = 0;
                                }
                                /* Schedule the idle thread if it isn't already */
                                if (!nfsrv_idlesock_timer_on) {
                                        nfs_interval_timer_start(nfsrv_idlesock_timer_call, time_to_wait * 1000);
                                        nfsrv_idlesock_timer_on = now.tv_sec + time_to_wait;
                                }
                        }
                }
        }

        sock_retain(so); /* grab a retain count on the socket */
        slp->ns_so = so;
        slp->ns_sotype = sotype;
        slp->ns_nam = mynam;

        /* set up the socket up-call */
        nfsrv_uc_addsock(slp, first);

        /* mark that the socket is not in the nfsrv_sockwg list */
        slp->ns_wgq.tqe_next = SLPNOLIST;

        slp->ns_flag = SLP_VALID | SLP_NEEDQ;

        nfsrv_wakenfsd(slp);
        lck_mtx_unlock(nfsd_mutex);

        return 0;
}

/*
 * nfssvc_nfsd()
 *
 * nfsd theory of operation:
 *
 * The first nfsd thread stays in user mode accepting new TCP connections
 * which are then added via the "addsock" call.  The rest of the nfsd threads
 * simply call into the kernel and remain there in a loop handling NFS
 * requests until killed by a signal.
 *
 * There's a list of nfsd threads (nfsd_head).
 * There's an nfsd queue that contains only those nfsds that are
 *   waiting for work to do (nfsd_queue).
 *
 * There's a list of all NFS sockets (nfsrv_socklist) and two queues for
 *   managing the work on the sockets:
 *   nfsrv_sockwait - sockets w/new data waiting to be worked on
 *   nfsrv_sockwork - sockets being worked on which may have more work to do
 *   nfsrv_sockwg -- sockets which have pending write gather data
 * When a socket receives data, if it is not currently queued, it
 *   will be placed at the end of the "wait" queue.
 * Whenever a socket needs servicing we make sure it is queued and
 *   wake up a waiting nfsd (if there is one).
 *
 * nfsds will service at most 8 requests from the same socket before
 *   defecting to work on another socket.
 * nfsds will defect immediately if there are any sockets in the "wait" queue
 * nfsds looking for a socket to work on check the "wait" queue first and
 *   then check the "work" queue.
 * When an nfsd starts working on a socket, it removes it from the head of
 *   the queue it's currently on and moves it to the end of the "work" queue.
 * When nfsds are checking the queues for work, any sockets found not to
 *   have any work are simply dropped from the queue.
 *
 */
int
nfssvc_nfsd(void)
{
        mbuf_t m, mrep;
        struct nfsrv_sock *slp;
        struct nfsd *nfsd;
        struct nfsrv_descript *nd = NULL;
        int error = 0, cacherep, writes_todo;
        int siz, procrastinate, opcnt = 0;
        u_quad_t cur_usec;
        struct timeval now;
        struct vfs_context context;
        struct timespec to;

#ifndef nolint
        cacherep = RC_DOIT;
        writes_todo = 0;
#endif

        MALLOC(nfsd, struct nfsd *, sizeof(struct nfsd), M_NFSD, M_WAITOK);
        if (!nfsd) {
                return ENOMEM;
        }
        bzero(nfsd, sizeof(struct nfsd));
        lck_mtx_lock(nfsd_mutex);
        if (nfsd_thread_count++ == 0) {
                nfsrv_initcache();              /* Init the server request cache */
        }
        TAILQ_INSERT_TAIL(&nfsd_head, nfsd, nfsd_chain);
        lck_mtx_unlock(nfsd_mutex);

        context.vc_thread = current_thread();

        /* Set time out so that nfsd threads can wake up a see if they are still needed. */
        to.tv_sec = 5;
        to.tv_nsec = 0;

        /*
         * Loop getting rpc requests until SIGKILL.
         */
        for (;;) {
                if (nfsd_thread_max <= 0) {
                        /* NFS server shutting down, get out ASAP */
                        error = EINTR;
                        slp = nfsd->nfsd_slp;
                } else if (nfsd->nfsd_flag & NFSD_REQINPROG) {
                        /* already have some work to do */
                        error = 0;
                        slp = nfsd->nfsd_slp;
                } else {
                        /* need to find work to do */
                        error = 0;
                        lck_mtx_lock(nfsd_mutex);
                        while (!nfsd->nfsd_slp && TAILQ_EMPTY(&nfsrv_sockwait) && TAILQ_EMPTY(&nfsrv_sockwork)) {
                                if (nfsd_thread_count > nfsd_thread_max) {
                                        /*
                                         * If we have no socket and there are more
                                         * nfsd threads than configured, let's exit.
                                         */
                                        error = 0;
                                        goto done;
                                }
                                nfsd->nfsd_flag |= NFSD_WAITING;
                                TAILQ_INSERT_HEAD(&nfsd_queue, nfsd, nfsd_queue);
                                error = msleep(nfsd, nfsd_mutex, PSOCK | PCATCH, "nfsd", &to);
                                if (error) {
                                        if (nfsd->nfsd_flag & NFSD_WAITING) {
                                                TAILQ_REMOVE(&nfsd_queue, nfsd, nfsd_queue);
                                                nfsd->nfsd_flag &= ~NFSD_WAITING;
                                        }
                                        if (error == EWOULDBLOCK) {
                                                continue;
                                        }
                                        goto done;
                                }
                        }
                        slp = nfsd->nfsd_slp;
                        if (!slp && !TAILQ_EMPTY(&nfsrv_sockwait)) {
                                /* look for a socket to work on in the wait queue */
                                while ((slp = TAILQ_FIRST(&nfsrv_sockwait))) {
                                        lck_rw_lock_exclusive(&slp->ns_rwlock);
                                        /* remove from the head of the queue */
                                        TAILQ_REMOVE(&nfsrv_sockwait, slp, ns_svcq);
                                        slp->ns_flag &= ~SLP_WAITQ;
                                        if ((slp->ns_flag & SLP_VALID) && (slp->ns_flag & SLP_WORKTODO)) {
                                                break;
                                        }
                                        /* nothing to do, so skip this socket */
                                        lck_rw_done(&slp->ns_rwlock);
                                }
                        }
                        if (!slp && !TAILQ_EMPTY(&nfsrv_sockwork)) {
                                /* look for a socket to work on in the work queue */
                                while ((slp = TAILQ_FIRST(&nfsrv_sockwork))) {
                                        lck_rw_lock_exclusive(&slp->ns_rwlock);
                                        /* remove from the head of the queue */
                                        TAILQ_REMOVE(&nfsrv_sockwork, slp, ns_svcq);
                                        slp->ns_flag &= ~SLP_WORKQ;
                                        if ((slp->ns_flag & SLP_VALID) && (slp->ns_flag & SLP_WORKTODO)) {
                                                break;
                                        }
                                        /* nothing to do, so skip this socket */
                                        lck_rw_done(&slp->ns_rwlock);
                                }
                        }
                        if (!nfsd->nfsd_slp && slp) {
                                /* we found a socket to work on, grab a reference */
                                slp->ns_sref++;
                                microuptime(&now);
                                slp->ns_timestamp = now.tv_sec;
                                /* We keep the socket list in least recently used order for reaping idle sockets */
                                TAILQ_REMOVE(&nfsrv_socklist, slp, ns_chain);
                                TAILQ_INSERT_TAIL(&nfsrv_socklist, slp, ns_chain);
                                nfsd->nfsd_slp = slp;
                                opcnt = 0;
                                /* and put it at the back of the work queue */
                                TAILQ_INSERT_TAIL(&nfsrv_sockwork, slp, ns_svcq);
                                slp->ns_flag |= SLP_WORKQ;
                                lck_rw_done(&slp->ns_rwlock);
                        }
                        lck_mtx_unlock(nfsd_mutex);
                        if (!slp) {
                                continue;
                        }
                        lck_rw_lock_exclusive(&slp->ns_rwlock);
                        if (slp->ns_flag & SLP_VALID) {
                                if ((slp->ns_flag & (SLP_NEEDQ | SLP_DISCONN)) == SLP_NEEDQ) {
                                        slp->ns_flag &= ~SLP_NEEDQ;
                                        nfsrv_rcv_locked(slp->ns_so, slp, MBUF_WAITOK);
                                }
                                if (slp->ns_flag & SLP_DISCONN) {
                                        nfsrv_zapsock(slp);
                                }
                                error = nfsrv_dorec(slp, nfsd, &nd);
                                if (error == EINVAL) {  // RPCSEC_GSS drop
                                        if (slp->ns_sotype == SOCK_STREAM) {
                                                nfsrv_zapsock(slp); // drop connection
                                        }
                                }
                                writes_todo = 0;
                                if (error && (slp->ns_wgtime || (slp->ns_flag & SLP_DOWRITES))) {
                                        microuptime(&now);
                                        cur_usec = (u_quad_t)now.tv_sec * 1000000 +
                                            (u_quad_t)now.tv_usec;
                                        if (slp->ns_wgtime <= cur_usec) {
                                                error = 0;
                                                cacherep = RC_DOIT;
                                                writes_todo = 1;
                                        }
                                        slp->ns_flag &= ~SLP_DOWRITES;
                                }
                                nfsd->nfsd_flag |= NFSD_REQINPROG;
                        }
                        lck_rw_done(&slp->ns_rwlock);
                }
                if (error || (slp && !(slp->ns_flag & SLP_VALID))) {
                        if (nd) {
                                nfsm_chain_cleanup(&nd->nd_nmreq);
                                if (nd->nd_nam2) {
                                        mbuf_freem(nd->nd_nam2);
                                }
                                if (IS_VALID_CRED(nd->nd_cr)) {
                                        kauth_cred_unref(&nd->nd_cr);
                                }
                                if (nd->nd_gss_context) {
                                        nfs_gss_svc_ctx_deref(nd->nd_gss_context);
                                }
                                FREE_ZONE(nd, sizeof(*nd), M_NFSRVDESC);
                                nd = NULL;
                        }
                        nfsd->nfsd_slp = NULL;
                        nfsd->nfsd_flag &= ~NFSD_REQINPROG;
                        if (slp) {
                                nfsrv_slpderef(slp);
                        }
                        if (nfsd_thread_max <= 0) {
                                break;
                        }
                        continue;
                }
                if (nd) {
                        microuptime(&nd->nd_starttime);
                        if (nd->nd_nam2) {
                                nd->nd_nam = nd->nd_nam2;
                        } else {
                                nd->nd_nam = slp->ns_nam;
                        }

                        cacherep = nfsrv_getcache(nd, slp, &mrep);

                        if (nfsrv_require_resv_port) {
                                /* Check if source port is a reserved port */
                                in_port_t port = 0;
                                struct sockaddr *saddr = mbuf_data(nd->nd_nam);

                                if (saddr->sa_family == AF_INET) {
                                        port = ntohs(((struct sockaddr_in*)saddr)->sin_port);
                                } else if (saddr->sa_family == AF_INET6) {
                                        port = ntohs(((struct sockaddr_in6*)saddr)->sin6_port);
                                }
                                if ((port >= IPPORT_RESERVED) && (nd->nd_procnum != NFSPROC_NULL)) {
                                        nd->nd_procnum = NFSPROC_NOOP;
                                        nd->nd_repstat = (NFSERR_AUTHERR | AUTH_TOOWEAK);
                                        cacherep = RC_DOIT;
                                }
                        }
                }

                /*
                 * Loop to get all the write RPC replies that have been
                 * gathered together.
                 */
                do {
                        switch (cacherep) {
                        case RC_DOIT:
                                if (nd && (nd->nd_vers == NFS_VER3)) {
                                        procrastinate = nfsrv_wg_delay_v3;
                                } else {
                                        procrastinate = nfsrv_wg_delay;
                                }
                                lck_rw_lock_shared(&nfsrv_export_rwlock);
                                context.vc_ucred = NULL;
                                if (writes_todo || ((nd->nd_procnum == NFSPROC_WRITE) && (procrastinate > 0))) {
                                        error = nfsrv_writegather(&nd, slp, &context, &mrep);
                                } else {
                                        error = (*(nfsrv_procs[nd->nd_procnum]))(nd, slp, &context, &mrep);
                                }
                                lck_rw_done(&nfsrv_export_rwlock);
                                if (mrep == NULL) {
                                        /*
                                         * If this is a stream socket and we are not going
                                         * to send a reply we better close the connection
                                         * so the client doesn't hang.
                                         */
                                        if (error && slp->ns_sotype == SOCK_STREAM) {
                                                lck_rw_lock_exclusive(&slp->ns_rwlock);
                                                nfsrv_zapsock(slp);
                                                lck_rw_done(&slp->ns_rwlock);
                                                printf("NFS server: NULL reply from proc = %d error = %d\n",
                                                    nd->nd_procnum, error);
                                        }
                                        break;
                                }
                                if (error) {
                                        OSAddAtomic64(1, &nfsstats.srv_errs);
                                        nfsrv_updatecache(nd, FALSE, mrep);
                                        if (nd->nd_nam2) {
                                                mbuf_freem(nd->nd_nam2);
                                                nd->nd_nam2 = NULL;
                                        }
                                        break;
                                }
                                OSAddAtomic64(1, &nfsstats.srvrpccnt[nd->nd_procnum]);
                                nfsrv_updatecache(nd, TRUE, mrep);
                        /* FALLTHRU */

                        case RC_REPLY:
                                if (nd->nd_gss_mb != NULL) { // It's RPCSEC_GSS
                                        /*
                                         * Need to checksum or encrypt the reply
                                         */
                                        error = nfs_gss_svc_protect_reply(nd, mrep);
                                        if (error) {
                                                mbuf_freem(mrep);
                                                break;
                                        }
                                }

                                /*
                                 * Get the total size of the reply
                                 */
                                m = mrep;
                                siz = 0;
                                while (m) {
                                        siz += mbuf_len(m);
                                        m = mbuf_next(m);
                                }
                                if (siz <= 0 || siz > NFS_MAXPACKET) {
                                        printf("mbuf siz=%d\n", siz);
                                        panic("Bad nfs svc reply");
                                }
                                m = mrep;
                                mbuf_pkthdr_setlen(m, siz);
                                error = mbuf_pkthdr_setrcvif(m, NULL);
                                if (error) {
                                        panic("nfsd setrcvif failed: %d", error);
                                }
                                /*
                                 * For stream protocols, prepend a Sun RPC
                                 * Record Mark.
                                 */
                                if (slp->ns_sotype == SOCK_STREAM) {
                                        error = mbuf_prepend(&m, NFSX_UNSIGNED, MBUF_WAITOK);
                                        if (!error) {
                                                *(u_int32_t*)mbuf_data(m) = htonl(0x80000000 | siz);
                                        }
                                }
                                if (!error) {
                                        if (slp->ns_flag & SLP_VALID) {
                                                error = nfsrv_send(slp, nd->nd_nam2, m);
                                        } else {
                                                error = EPIPE;
                                                mbuf_freem(m);
                                        }
                                } else {
                                        mbuf_freem(m);
                                }
                                mrep = NULL;
                                if (nd->nd_nam2) {
                                        mbuf_freem(nd->nd_nam2);
                                        nd->nd_nam2 = NULL;
                                }
                                if (error == EPIPE) {
                                        lck_rw_lock_exclusive(&slp->ns_rwlock);
                                        nfsrv_zapsock(slp);
                                        lck_rw_done(&slp->ns_rwlock);
                                }
                                if (error == EINTR || error == ERESTART) {
                                        nfsm_chain_cleanup(&nd->nd_nmreq);
                                        if (IS_VALID_CRED(nd->nd_cr)) {
                                                kauth_cred_unref(&nd->nd_cr);
                                        }
                                        if (nd->nd_gss_context) {
                                                nfs_gss_svc_ctx_deref(nd->nd_gss_context);
                                        }
                                        FREE_ZONE(nd, sizeof(*nd), M_NFSRVDESC);
                                        nfsrv_slpderef(slp);
                                        lck_mtx_lock(nfsd_mutex);
                                        goto done;
                                }
                                break;
                        case RC_DROPIT:
                                mbuf_freem(nd->nd_nam2);
                                nd->nd_nam2 = NULL;
                                break;
                        }
                        ;
                        opcnt++;
                        if (nd) {
                                nfsm_chain_cleanup(&nd->nd_nmreq);
                                if (nd->nd_nam2) {
                                        mbuf_freem(nd->nd_nam2);
                                }
                                if (IS_VALID_CRED(nd->nd_cr)) {
                                        kauth_cred_unref(&nd->nd_cr);
                                }
                                if (nd->nd_gss_context) {
                                        nfs_gss_svc_ctx_deref(nd->nd_gss_context);
                                }
                                FREE_ZONE(nd, sizeof(*nd), M_NFSRVDESC);
                                nd = NULL;
                        }

                        /*
                         * Check to see if there are outstanding writes that
                         * need to be serviced.
                         */
                        writes_todo = 0;
                        if (slp->ns_wgtime) {
                                microuptime(&now);
                                cur_usec = (u_quad_t)now.tv_sec * 1000000 +
                                    (u_quad_t)now.tv_usec;
                                if (slp->ns_wgtime <= cur_usec) {
                                        cacherep = RC_DOIT;
                                        writes_todo = 1;
                                }
                        }
                } while (writes_todo);

                nd = NULL;
                if (TAILQ_EMPTY(&nfsrv_sockwait) && (opcnt < 8)) {
                        lck_rw_lock_exclusive(&slp->ns_rwlock);
                        error = nfsrv_dorec(slp, nfsd, &nd);
                        if (error == EINVAL) {  // RPCSEC_GSS drop
                                if (slp->ns_sotype == SOCK_STREAM) {
                                        nfsrv_zapsock(slp); // drop connection
                                }
                        }
                        lck_rw_done(&slp->ns_rwlock);
                }
                if (!nd) {
                        /* drop our reference on the socket */
                        nfsd->nfsd_flag &= ~NFSD_REQINPROG;
                        nfsd->nfsd_slp = NULL;
                        nfsrv_slpderef(slp);
                }
        }
        lck_mtx_lock(nfsd_mutex);
done:
        TAILQ_REMOVE(&nfsd_head, nfsd, nfsd_chain);
        FREE(nfsd, M_NFSD);
        if (--nfsd_thread_count == 0) {
                nfsrv_cleanup();
        }
        lck_mtx_unlock(nfsd_mutex);
        return error;
}

int
nfssvc_export(user_addr_t argp)
{
        int error = 0, is_64bit;
        struct user_nfs_export_args unxa;
        vfs_context_t ctx = vfs_context_current();

        is_64bit = IS_64BIT_PROCESS(vfs_context_proc(ctx));

        /* copy in pointers to path and export args */
        if (is_64bit) {
                error = copyin(argp, (caddr_t)&unxa, sizeof(unxa));
        } else {
                struct nfs_export_args tnxa;
                error = copyin(argp, (caddr_t)&tnxa, sizeof(tnxa));
                if (error == 0) {
                        /* munge into LP64 version of nfs_export_args structure */
                        unxa.nxa_fsid = tnxa.nxa_fsid;
                        unxa.nxa_expid = tnxa.nxa_expid;
                        unxa.nxa_fspath = CAST_USER_ADDR_T(tnxa.nxa_fspath);
                        unxa.nxa_exppath = CAST_USER_ADDR_T(tnxa.nxa_exppath);
                        unxa.nxa_flags = tnxa.nxa_flags;
                        unxa.nxa_netcount = tnxa.nxa_netcount;
                        unxa.nxa_nets = CAST_USER_ADDR_T(tnxa.nxa_nets);
                }
        }
        if (error) {
                return error;
        }

        error = nfsrv_export(&unxa, ctx);

        return error;
}

/*
 * Shut down a socket associated with an nfsrv_sock structure.
 * Should be called with the send lock set, if required.
 * The trick here is to increment the sref at the start, so that the nfsds
 * will stop using it and clear ns_flag at the end so that it will not be
 * reassigned during cleanup.
 */
void
nfsrv_zapsock(struct nfsrv_sock *slp)
{
        socket_t so;

        if ((slp->ns_flag & SLP_VALID) == 0) {
                return;
        }
        slp->ns_flag &= ~SLP_ALLFLAGS;

        so = slp->ns_so;
        if (so == NULL) {
                return;
        }

        sock_setupcall(so, NULL, NULL);
        sock_shutdown(so, SHUT_RDWR);

        /*
         * Remove from the up-call queue
         */
        nfsrv_uc_dequeue(slp);
}

/*
 * cleanup and release a server socket structure.
 */
void
nfsrv_slpfree(struct nfsrv_sock *slp)
{
        struct nfsrv_descript *nwp, *nnwp;

        if (slp->ns_so) {
                sock_release(slp->ns_so);
                slp->ns_so = NULL;
        }
        if (slp->ns_nam) {
                mbuf_free(slp->ns_nam);
        }
        if (slp->ns_raw) {
                mbuf_freem(slp->ns_raw);
        }
        if (slp->ns_rec) {
                mbuf_freem(slp->ns_rec);
        }
        if (slp->ns_frag) {
                mbuf_freem(slp->ns_frag);
        }
        slp->ns_nam = slp->ns_raw = slp->ns_rec = slp->ns_frag = NULL;
        slp->ns_reccnt = 0;

        for (nwp = slp->ns_tq.lh_first; nwp; nwp = nnwp) {
                nnwp = nwp->nd_tq.le_next;
                LIST_REMOVE(nwp, nd_tq);
                nfsm_chain_cleanup(&nwp->nd_nmreq);
                if (nwp->nd_mrep) {
                        mbuf_freem(nwp->nd_mrep);
                }
                if (nwp->nd_nam2) {
                        mbuf_freem(nwp->nd_nam2);
                }
                if (IS_VALID_CRED(nwp->nd_cr)) {
                        kauth_cred_unref(&nwp->nd_cr);
                }
                if (nwp->nd_gss_context) {
                        nfs_gss_svc_ctx_deref(nwp->nd_gss_context);
                }
                FREE_ZONE(nwp, sizeof(*nwp), M_NFSRVDESC);
        }
        LIST_INIT(&slp->ns_tq);

        lck_rw_destroy(&slp->ns_rwlock, nfsrv_slp_rwlock_group);
        lck_mtx_destroy(&slp->ns_wgmutex, nfsrv_slp_mutex_group);
        FREE(slp, M_NFSSVC);
}

/*
 * Derefence a server socket structure. If it has no more references and
 * is no longer valid, you can throw it away.
 */
static void
nfsrv_slpderef_locked(struct nfsrv_sock *slp)
{
        lck_rw_lock_exclusive(&slp->ns_rwlock);
        slp->ns_sref--;

        if (slp->ns_sref || (slp->ns_flag & SLP_VALID)) {
                if ((slp->ns_flag & SLP_QUEUED) && !(slp->ns_flag & SLP_WORKTODO)) {
                        /* remove socket from queue since there's no work */
                        if (slp->ns_flag & SLP_WAITQ) {
                                TAILQ_REMOVE(&nfsrv_sockwait, slp, ns_svcq);
                        } else {
                                TAILQ_REMOVE(&nfsrv_sockwork, slp, ns_svcq);
                        }
                        slp->ns_flag &= ~SLP_QUEUED;
                }
                lck_rw_done(&slp->ns_rwlock);
                return;
        }

        /* This socket is no longer valid, so we'll get rid of it */

        if (slp->ns_flag & SLP_QUEUED) {
                if (slp->ns_flag & SLP_WAITQ) {
                        TAILQ_REMOVE(&nfsrv_sockwait, slp, ns_svcq);
                } else {
                        TAILQ_REMOVE(&nfsrv_sockwork, slp, ns_svcq);
                }
                slp->ns_flag &= ~SLP_QUEUED;
        }
        lck_rw_done(&slp->ns_rwlock);

        TAILQ_REMOVE(&nfsrv_socklist, slp, ns_chain);
        if (slp->ns_sotype == SOCK_STREAM) {
                nfsrv_sock_tcp_cnt--;
        }

        /* now remove from the write gather socket list */
        if (slp->ns_wgq.tqe_next != SLPNOLIST) {
                TAILQ_REMOVE(&nfsrv_sockwg, slp, ns_wgq);
                slp->ns_wgq.tqe_next = SLPNOLIST;
        }
        nfsrv_slpfree(slp);
}

void
nfsrv_slpderef(struct nfsrv_sock *slp)
{
        lck_mtx_lock(nfsd_mutex);
        nfsrv_slpderef_locked(slp);
        lck_mtx_unlock(nfsd_mutex);
}

/*
 * Check periodically for idle sockest if needed and
 * zap them.
 */
void
nfsrv_idlesock_timer(__unused void *param0, __unused void *param1)
{
        struct nfsrv_sock *slp, *tslp;
        struct timeval now;
        time_t time_to_wait = nfsrv_sock_idle_timeout;

        microuptime(&now);
        lck_mtx_lock(nfsd_mutex);

        /* Turn off the timer if we're suppose to and get out */
        if (nfsrv_sock_idle_timeout < NFSD_MIN_IDLE_TIMEOUT) {
                nfsrv_sock_idle_timeout = 0;
        }
        if ((nfsrv_sock_tcp_cnt <= 2 * nfsd_thread_max) || (nfsrv_sock_idle_timeout == 0)) {
                nfsrv_idlesock_timer_on = 0;
                lck_mtx_unlock(nfsd_mutex);
                return;
        }

        TAILQ_FOREACH_SAFE(slp, &nfsrv_socklist, ns_chain, tslp) {
                lck_rw_lock_exclusive(&slp->ns_rwlock);
                /* Skip udp and referenced sockets */
                if (slp->ns_sotype == SOCK_DGRAM || slp->ns_sref) {
                        lck_rw_done(&slp->ns_rwlock);
                        continue;
                }
                /*
                 * If this is the first non-referenced socket that hasn't idle out,
                 * use its time stamp to calculate the earlist time in the future
                 * to start the next invocation of the timer. Since the nfsrv_socklist
                 * is sorted oldest access to newest. Once we find the first one,
                 * we're done and break out of the loop.
                 */
                if (((slp->ns_timestamp + nfsrv_sock_idle_timeout) > now.tv_sec) ||
                    nfsrv_sock_tcp_cnt <= 2 * nfsd_thread_max) {
                        time_to_wait -= now.tv_sec - slp->ns_timestamp;
                        if (time_to_wait < 1) {
                                time_to_wait = 1;
                        }
                        lck_rw_done(&slp->ns_rwlock);
                        break;
                }
                /*
                 * Bump the ref count. nfsrv_slpderef below will destroy
                 * the socket, since nfsrv_zapsock has closed it.
                 */
                slp->ns_sref++;
                nfsrv_zapsock(slp);
                lck_rw_done(&slp->ns_rwlock);
                nfsrv_slpderef_locked(slp);
        }

        /* Start ourself back up */
        nfs_interval_timer_start(nfsrv_idlesock_timer_call, time_to_wait * 1000);
        /* Remember when the next timer will fire for nfssvc_addsock. */
        nfsrv_idlesock_timer_on = now.tv_sec + time_to_wait;
        lck_mtx_unlock(nfsd_mutex);
}

/*
 * Clean up the data structures for the server.
 */
void
nfsrv_cleanup(void)
{
        struct nfsrv_sock *slp, *nslp;
        struct timeval now;
#if CONFIG_FSE
        struct nfsrv_fmod *fp, *nfp;
        int i;
#endif

        microuptime(&now);
        for (slp = TAILQ_FIRST(&nfsrv_socklist); slp != 0; slp = nslp) {
                nslp = TAILQ_NEXT(slp, ns_chain);
                lck_rw_lock_exclusive(&slp->ns_rwlock);
                slp->ns_sref++;
                if (slp->ns_flag & SLP_VALID) {
                        nfsrv_zapsock(slp);
                }
                lck_rw_done(&slp->ns_rwlock);
                nfsrv_slpderef_locked(slp);
        }
#
#if CONFIG_FSE
        /*
         * Flush pending file write fsevents
         */
        lck_mtx_lock(nfsrv_fmod_mutex);
        for (i = 0; i < NFSRVFMODHASHSZ; i++) {
                for (fp = LIST_FIRST(&nfsrv_fmod_hashtbl[i]); fp; fp = nfp) {
                        /*
                         * Fire off the content modified fsevent for each
                         * entry, remove it from the list, and free it.
                         */
                        if (nfsrv_fsevents_enabled) {
                                fp->fm_context.vc_thread = current_thread();
                                add_fsevent(FSE_CONTENT_MODIFIED, &fp->fm_context,
                                    FSE_ARG_VNODE, fp->fm_vp,
                                    FSE_ARG_DONE);
                        }
                        vnode_put(fp->fm_vp);
                        kauth_cred_unref(&fp->fm_context.vc_ucred);
                        nfp = LIST_NEXT(fp, fm_link);
                        LIST_REMOVE(fp, fm_link);
                        FREE(fp, M_TEMP);
                }
        }
        nfsrv_fmod_pending = 0;
        lck_mtx_unlock(nfsrv_fmod_mutex);
#endif

        nfsrv_uc_cleanup();     /* Stop nfs socket up-call threads */

        nfs_gss_svc_cleanup();  /* Remove any RPCSEC_GSS contexts */

        nfsrv_cleancache();     /* And clear out server cache */

        nfsrv_udpsock = NULL;
        nfsrv_udp6sock = NULL;
}

#endif /* NFS_NOSERVER */