xref: /illumos-gate/usr/src/cmd/fs.d/nfs/mountd/mountd.c (revision 3db86aab)

/*
 * 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 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <sys/types.h>
#include <string.h>
#include <syslog.h>
#include <sys/param.h>
#include <rpc/rpc.h>
#include <sys/stat.h>
#include <netconfig.h>
#include <netdir.h>
#include <sys/file.h>
#include <sys/time.h>
#include <sys/errno.h>
#include <rpcsvc/mount.h>
#include <sys/pathconf.h>
#include <sys/systeminfo.h>
#include <sys/utsname.h>
#include <signal.h>
#include <locale.h>
#include <unistd.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <thread.h>
#include <assert.h>
#include <priv_utils.h>
#include <nfs/auth.h>
#include <nfs/nfssys.h>
#include <nfs/nfs.h>
#include <nfs/nfs_sec.h>
#include <rpcsvc/daemon_utils.h>
#include <deflt.h>
#include "../../fslib.h"
#include "../lib/sharetab.h"
#include "mountd.h"

struct sh_list *share_list;

rwlock_t sharetab_lock;		/* lock to protect the cached sharetab */
static mutex_t mnttab_lock;	/* prevent concurrent mnttab readers */

static struct share *find_lofsentry(char *, int *);
static void getclientsnames(SVCXPRT *, struct netbuf **,
					struct nd_hostservlist **);
static int getclientsflavors_old(struct share *, struct netbuf *,
	struct nd_hostservlist *, int *);
static int getclientsflavors_new(struct share *, struct netbuf *,
	struct nd_hostservlist *, int *);
static int check_client_old(struct share *, struct netbuf *,
    struct nd_hostservlist *, int);
static int check_client_new(struct share *, struct netbuf *,
	struct nd_hostservlist *, int);
static int  in_access_list(struct netbuf *, struct nd_hostservlist *, char *);
static void mnt(struct svc_req *, SVCXPRT *);
static void mnt_pathconf(struct svc_req *);
static void mount(struct svc_req *r);
static void sh_free(struct sh_list *);
static void umount(struct svc_req *);
static void umountall(struct svc_req *);
static int netmatch(struct netbuf *, char *);
static void sigexit(int);
static int newopts(char *);

static int verbose;
static int rejecting;
static int mount_vers_min = MOUNTVERS;
static int mount_vers_max = MOUNTVERS3;

thread_t	nfsauth_thread;

/* ARGSUSED */
static void *
nfsauth_svc(void *arg)
{
	int	doorfd = -1;
	uint_t	darg;
#ifdef DEBUG
	int	dfd;
#endif

	if ((doorfd = door_create(nfsauth_func, NULL,
	    DOOR_REFUSE_DESC | DOOR_NO_CANCEL)) == -1) {
		syslog(LOG_ERR, "Unable to create door: %m\n");
		exit(10);
	}

#ifdef DEBUG
	/*
	 * Create a file system path for the door
	 */
	if ((dfd = open(MOUNTD_DOOR, O_RDWR|O_CREAT|O_TRUNC,
	    S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)) == -1) {
		syslog(LOG_ERR, "Unable to open %s: %m\n", MOUNTD_DOOR);
		(void) close(doorfd);
		exit(11);
	}

	/*
	 * Clean up any stale namespace associations
	 */
	(void) fdetach(MOUNTD_DOOR);

	/*
	 * Register in namespace to pass to the kernel to door_ki_open
	 */
	if (fattach(doorfd, MOUNTD_DOOR) == -1) {
		syslog(LOG_ERR, "Unable to fattach door: %m\n");
		(void) close(dfd);
		(void) close(doorfd);
		exit(12);
	}
	(void) close(dfd);
#endif

	/*
	 * Must pass the doorfd down to the kernel.
	 */
	darg = doorfd;
	(void) _nfssys(MOUNTD_ARGS, &darg);

	/*
	 * Wait for incoming calls
	 */
	/*CONSTCOND*/
	for (;;)
		(void) pause();

	/*NOTREACHED*/
	syslog(LOG_ERR, gettext("Door server exited"));
	return (NULL);
}

int
main(int argc, char *argv[])
{
	int	pid;
	int	c;
	int	rpc_svc_mode = RPC_SVC_MT_AUTO;
	int	maxthreads;
	int	maxrecsz = RPC_MAXDATASIZE;
	bool_t	exclbind = TRUE;
	bool_t	can_do_mlp;
	long	thr_flags = (THR_NEW_LWP|THR_DAEMON);

	/*
	 * Mountd requires uid 0 for:
	 *	/etc/rmtab updates (we could chown it to daemon)
	 *	/etc/dfs/dfstab reading (it wants to lock out share which
	 *		doesn't do any locking before first truncate;
	 *		NFS share does; should use fcntl locking instead)
	 *	Needed privileges:
	 *		auditing
	 *		nfs syscall
	 *		file dac search (so it can stat all files)
	 *	Optional privileges:
	 *		MLP
	 */
	can_do_mlp = priv_ineffect(PRIV_NET_BINDMLP);
	if (__init_daemon_priv(PU_RESETGROUPS|PU_CLEARLIMITSET, -1, -1,
	    PRIV_SYS_NFS, PRIV_PROC_AUDIT, PRIV_FILE_DAC_SEARCH,
	    can_do_mlp ? PRIV_NET_BINDMLP : NULL, NULL) == -1) {
		(void) fprintf(stderr,
			"%s must be run as with sufficient privileges\n",
			argv[0]);
		exit(1);
	}

	maxthreads = 0;

	while ((c = getopt(argc, argv, "vrm:")) != EOF) {
		switch (c) {
		case 'v':
			verbose++;
			break;
		case 'r':
			rejecting = 1;
			break;
		case 'm':
			maxthreads = atoi(optarg);
			if (maxthreads < 1) {
				(void) fprintf(stderr,
	"%s: must specify positive maximum threads count, using default\n",
						argv[0]);
				maxthreads = 0;
			}
			break;
		}
	}

	/*
	 * Read in the NFS version values from config file.
	 */
	if ((defopen(NFSADMIN)) == 0) {
		char *defval;
		int defvers;

		if ((defval = defread("NFS_SERVER_VERSMIN=")) != NULL) {
			errno = 0;
			defvers = strtol(defval, (char **)NULL, 10);
			if (errno == 0) {
				mount_vers_min = defvers;
				/*
				 * special because NFSv2 is
				 * supported by mount v1 & v2
				 */
				if (defvers == NFS_VERSION)
					mount_vers_min = MOUNTVERS;
			}
		}
		if ((defval = defread("NFS_SERVER_VERSMAX=")) != NULL) {
			errno = 0;
			defvers = strtol(defval, (char **)NULL, 10);
			if (errno == 0) {
				mount_vers_max = defvers;
			}
		}

		/* close defaults file */
		defopen(NULL);
	}

	/*
	 * Sanity check versions,
	 * even though we may get versions > MOUNTVERS3, we still need
	 * to start nfsauth service, so continue on regardless of values.
	 */
	if (mount_vers_min > mount_vers_max) {
		syslog(LOG_NOTICE, "NFS_SERVER_VERSMIN > NFS_SERVER_VERSMAX");
		mount_vers_max = mount_vers_min;
	}
	(void) setlocale(LC_ALL, "");
	(void) rwlock_init(&sharetab_lock, USYNC_THREAD, NULL);
	(void) mutex_init(&mnttab_lock, USYNC_THREAD, NULL);
	netgroup_init();

#if !defined(TEXT_DOMAIN)
#define	TEXT_DOMAIN "SYS_TEST"
#endif
	(void) textdomain(TEXT_DOMAIN);

	/* Don't drop core if the NFS module isn't loaded. */
	(void) signal(SIGSYS, SIG_IGN);

	(void) signal(SIGHUP, sigexit);
	(void) signal(SIGCLD, sigexit);

	switch (fork()) {
	case 0:		/* child */
		break;
	case -1:
		perror("mountd: can't fork");
		exit(1);
	default:	/* parent */
		for (;;)
			(void) pause();
		/* NOTREACHED */
	}

	(void) signal(SIGHUP, SIG_DFL);
	(void) signal(SIGCLD, SIG_DFL);

	/*
	 * If we coredump it'll be in /core
	 */
	if (chdir("/") < 0)
		syslog(LOG_ERR, "chdir /: %m");

	/*
	 * Close existing file descriptors, open "/dev/null" as
	 * standard input, output, and error, and detach from
	 * controlling terminal.
	 */
	closefrom(0);
	(void) open("/dev/null", O_RDONLY);
	(void) open("/dev/null", O_WRONLY);
	(void) dup(1);
	(void) setsid();

	openlog("mountd", LOG_PID, LOG_DAEMON);

	/*
	 * establish our lock on the lock file and write our pid to it.
	 * exit if some other process holds the lock, or if there's any
	 * error in writing/locking the file.
	 */
	pid = _enter_daemon_lock(MOUNTD);
	switch (pid) {
	case 0:
		break;
	case -1:
		syslog(LOG_ERR, "error locking for %s: %s", MOUNTD,
		    strerror(errno));
		exit(2);
	default:
		/* daemon was already running */
		exit(0);
	}

	audit_mountd_setup();	/* BSM */

	/*
	 * Tell RPC that we want automatic thread mode.
	 * A new thread will be spawned for each request.
	 */
	if (!rpc_control(RPC_SVC_MTMODE_SET, &rpc_svc_mode)) {
		syslog(LOG_ERR, "unable to set automatic MT mode");
		exit(1);
	}

	/*
	 * Enable non-blocking mode and maximum record size checks for
	 * connection oriented transports.
	 */
	if (!rpc_control(RPC_SVC_CONNMAXREC_SET, &maxrecsz)) {
		syslog(LOG_INFO, "unable to set RPC max record size");
	}

	/*
	 * Prevent our non-priv udp and tcp ports bound w/wildcard addr
	 * from being hijacked by a bind to a more specific addr.
	 */
	if (!rpc_control(__RPC_SVC_EXCLBIND_SET, &exclbind)) {
		syslog(LOG_INFO,  "warning: unable to set udp/tcp EXCLBIND");
	}

	/*
	 * If the -m argument was specified, then set the
	 * maximum number of threads to the value specified.
	 */
	if (maxthreads > 0 && !rpc_control(RPC_SVC_THRMAX_SET, &maxthreads)) {
		syslog(LOG_ERR, "unable to set maxthreads");
		exit(1);
	}

	/*
	 * Make sure to unregister any previous versions in case the
	 * user is reconfiguring the server in interesting ways.
	 */
	svc_unreg(MOUNTPROG, MOUNTVERS);
	svc_unreg(MOUNTPROG, MOUNTVERS_POSIX);
	svc_unreg(MOUNTPROG, MOUNTVERS3);

	/*
	 * Create the nfsauth thread with same signal disposition
	 * as the main thread. We need to create a separate thread
	 * since mountd() will be both an RPC server (for remote
	 * traffic) _and_ a doors server (for kernel upcalls).
	 */
	if (thr_create(NULL, 0, nfsauth_svc, 0, thr_flags, &nfsauth_thread)) {
		syslog(LOG_ERR, gettext("Failed to create NFSAUTH svc thread"));
		exit(2);
	}

	/*
	 * Create datagram and connection oriented services
	 */
	if (mount_vers_max >= MOUNTVERS) {
		if (svc_create(mnt, MOUNTPROG, MOUNTVERS, "datagram_v") == 0) {
			syslog(LOG_ERR,
				"couldn't register datagram_v MOUNTVERS");
			exit(1);
		}
		if (svc_create(mnt, MOUNTPROG, MOUNTVERS, "circuit_v") == 0) {
			syslog(LOG_ERR,
				"couldn't register circuit_v MOUNTVERS");
			exit(1);
		}
	}
	if (mount_vers_max >= MOUNTVERS_POSIX) {
		if (svc_create(mnt, MOUNTPROG, MOUNTVERS_POSIX,
							"datagram_v") == 0) {
			syslog(LOG_ERR,
				"couldn't register datagram_v MOUNTVERS_POSIX");
			exit(1);
		}
		if (svc_create(mnt, MOUNTPROG, MOUNTVERS_POSIX,
							"circuit_v") == 0) {
			syslog(LOG_ERR,
				"couldn't register circuit_v MOUNTVERS_POSIX");
			exit(1);
		}
	}

	if (mount_vers_max >= MOUNTVERS3) {
		if (svc_create(mnt, MOUNTPROG, MOUNTVERS3, "datagram_v") == 0) {
			syslog(LOG_ERR,
				"couldn't register datagram_v MOUNTVERS3");
			exit(1);
		}
		if (svc_create(mnt, MOUNTPROG, MOUNTVERS3, "circuit_v") == 0) {
			syslog(LOG_ERR,
				"couldn't register circuit_v MOUNTVERS3");
			exit(1);
		}
	}

	/*
	 * Start serving
	 */
	rmtab_load();
	(void) kill(getppid(), SIGHUP);

	/* Get rid of the most dangerous basic privileges. */
	__fini_daemon_priv(PRIV_PROC_EXEC, PRIV_PROC_INFO, PRIV_PROC_SESSION,
	    (char *)NULL);

	svc_run();
	syslog(LOG_ERR, "Error: svc_run shouldn't have returned");
	abort();
	/* NOTREACHED */
	return (0);
}

/*
 * Server procedure switch routine
 */
void
mnt(struct svc_req *rqstp, SVCXPRT *transp)
{
	switch (rqstp->rq_proc) {
	case NULLPROC:
		errno = 0;
		if (!svc_sendreply(transp, xdr_void, (char *)0))
			log_cant_reply(transp);
		return;

	case MOUNTPROC_MNT:
		mount(rqstp);
		return;

	case MOUNTPROC_DUMP:
		mntlist_send(transp);
		return;

	case MOUNTPROC_UMNT:
		umount(rqstp);
		return;

	case MOUNTPROC_UMNTALL:
		umountall(rqstp);
		return;

	case MOUNTPROC_EXPORT:
	case MOUNTPROC_EXPORTALL:
		export(rqstp);
		return;

	case MOUNTPROC_PATHCONF:
		if (rqstp->rq_vers == MOUNTVERS_POSIX)
			mnt_pathconf(rqstp);
		else
			svcerr_noproc(transp);
		return;

	default:
		svcerr_noproc(transp);
		return;
	}
}

/* Set up anonymous client */

struct nd_hostservlist *
anon_client(char *host)
{
	struct nd_hostservlist *anon_hsl;
	struct nd_hostserv *anon_hs;

	anon_hsl = malloc(sizeof (*anon_hsl));
	if (anon_hsl == NULL)
		return (NULL);

	anon_hs = malloc(sizeof (*anon_hs));
	if (anon_hs == NULL) {
		free(anon_hsl);
		return (NULL);
	}

	if (host == NULL)
		anon_hs->h_host = strdup("(anon)");
	else
		anon_hs->h_host = strdup(host);

	if (anon_hs->h_host == NULL) {
		free(anon_hs);
		free(anon_hsl);
		return (NULL);
	}
	anon_hs->h_serv = '\0';

	anon_hsl->h_cnt = 1;
	anon_hsl->h_hostservs = anon_hs;

	return (anon_hsl);
}

/*
 * Get the client's hostname from the transport handle
 * If the name is not available then return "(anon)".
 */
void
getclientsnames(SVCXPRT *transp, struct netbuf **nbuf,
    struct nd_hostservlist **serv)
{
	struct netconfig *nconf;
	char tmp[MAXIPADDRLEN];
	char *host = NULL;

	nconf = getnetconfigent(transp->xp_netid);
	if (nconf == NULL) {
		syslog(LOG_ERR, "%s: getnetconfigent failed",
			transp->xp_netid);
		*serv = anon_client(host);
		return;
	}

	*nbuf = svc_getrpccaller(transp);
	if (*nbuf == NULL) {
		freenetconfigent(nconf);
		*serv = anon_client(host);
		return;
	}

	/*
	 * Use the this API instead of the netdir_getbyaddr()
	 * to avoid service lookup.
	 */
	if (__netdir_getbyaddr_nosrv(nconf, serv, *nbuf)) {
		host = &tmp[0];
		if (strcmp(nconf->nc_protofmly, NC_INET) == 0) {
			struct sockaddr_in *sa;

			/* LINTED pointer alignment */
			sa = (struct sockaddr_in *)((*nbuf)->buf);
			(void) inet_ntoa_r(sa->sin_addr, tmp);
			*serv =	anon_client(host);
			freenetconfigent(nconf);
			return;
		} else if (strcmp(nconf->nc_protofmly, NC_INET6) == 0) {
			struct sockaddr_in6 *sa;

			/* LINTED pointer alignment */
			sa = (struct sockaddr_in6 *)((*nbuf)->buf);
			(void) inet_ntop(AF_INET6, sa->sin6_addr.s6_addr,
					tmp, INET6_ADDRSTRLEN);
			*serv =	anon_client(host);
			freenetconfigent(nconf);
			return;
		}
		freenetconfigent(nconf);
		*serv = anon_client(host);
		return;
	}
	freenetconfigent(nconf);
}

void
log_cant_reply(SVCXPRT *transp)
{
	int saverrno;
	struct nd_hostservlist *clnames = NULL;
	register char *host;
	struct netbuf *nb;

	saverrno = errno;	/* save error code */
	getclientsnames(transp, &nb, &clnames);
	if (clnames == NULL)
		return;
	host = clnames->h_hostservs->h_host;

	errno = saverrno;
	if (errno == 0)
		syslog(LOG_ERR, "couldn't send reply to %s", host);
	else
		syslog(LOG_ERR, "couldn't send reply to %s: %m", host);

	netdir_free(clnames, ND_HOSTSERVLIST);
}

/*
 * Answer pathconf questions for the mount point fs
 */
static void
mnt_pathconf(struct svc_req *rqstp)
{
	SVCXPRT *transp;
	struct pathcnf p;
	char *path, rpath[MAXPATHLEN];
	struct stat st;

	transp = rqstp->rq_xprt;
	path = NULL;
	(void) memset((caddr_t)&p, 0, sizeof (p));

	if (!svc_getargs(transp, xdr_dirpath, (caddr_t)&path)) {
		svcerr_decode(transp);
		return;
	}
	if (lstat(path, &st) < 0) {
		_PC_SET(_PC_ERROR, p.pc_mask);
		goto done;
	}
	/*
	 * Get a path without symbolic links.
	 */
	if (realpath(path, rpath) == NULL) {
		syslog(LOG_DEBUG,
			"mount request: realpath failed on %s: %m",
			path);
		_PC_SET(_PC_ERROR, p.pc_mask);
		goto done;
	}
	(void) memset((caddr_t)&p, 0, sizeof (p));
	/*
	 * can't ask about devices over NFS
	 */
	_PC_SET(_PC_MAX_CANON, p.pc_mask);
	_PC_SET(_PC_MAX_INPUT, p.pc_mask);
	_PC_SET(_PC_PIPE_BUF, p.pc_mask);
	_PC_SET(_PC_VDISABLE, p.pc_mask);

	errno = 0;
	p.pc_link_max = pathconf(rpath, _PC_LINK_MAX);
	if (errno)
		_PC_SET(_PC_LINK_MAX, p.pc_mask);
	p.pc_name_max = pathconf(rpath, _PC_NAME_MAX);
	if (errno)
		_PC_SET(_PC_NAME_MAX, p.pc_mask);
	p.pc_path_max = pathconf(rpath, _PC_PATH_MAX);
	if (errno)
		_PC_SET(_PC_PATH_MAX, p.pc_mask);
	if (pathconf(rpath, _PC_NO_TRUNC) == 1)
		_PC_SET(_PC_NO_TRUNC, p.pc_mask);
	if (pathconf(rpath, _PC_CHOWN_RESTRICTED) == 1)
		_PC_SET(_PC_CHOWN_RESTRICTED, p.pc_mask);

done:
	errno = 0;
	if (!svc_sendreply(transp, xdr_ppathcnf, (char *)&p))
		log_cant_reply(transp);
	if (path != NULL)
		svc_freeargs(transp, xdr_dirpath, (caddr_t)&path);
}

/*
 * If the rootmount (export) option is specified, the all mount requests for
 * subdirectories return EACCES.
 */
static int
checkrootmount(struct share *sh, char *rpath)
{
	char *val;

	if ((val = getshareopt(sh->sh_opts, SHOPT_NOSUB)) != NULL) {
		free(val);
		if (strcmp(sh->sh_path, rpath) != 0)
			return (0);
		else
			return (1);
	} else
		return (1);
}

#define	MAX_FLAVORS	128

/*
 * Return only EACCES if client does not have access
 *  to this directory.
 * "If the server exports only /a/b, an attempt to
 *  mount a/b/c will fail with ENOENT if the directory
 *  does not exist"... However, if the client
 *  does not have access to /a/b, an attacker can
 *  determine whether the directory exists.
 * This routine checks either existence of the file or
 * existence of the file name entry in the mount table.
 * If the file exists and there is no file name entry,
 * the error returned should be EACCES.
 * If the file does not exist, it must be determined
 * whether the client has access to a parent
 * directory.  If the client has access to a parent
 * directory, the error returned should be ENOENT,
 * otherwise EACCES.
 */
static int
mount_enoent_error(char *path, char *rpath, struct nd_hostservlist *clnames,
    struct netbuf *nb, int *flavor_list)
{
	char *checkpath, *dp;
	struct share *sh = NULL;
	int realpath_error = ENOENT, reply_error = EACCES, lofs_tried = 0;
	int flavor_count;

	checkpath = strdup(path);
	if (checkpath == NULL) {
		syslog(LOG_ERR, "mount_enoent: no memory");
		return (EACCES);
	}

	/* CONSTCOND */
	while (1) {
		if (sh) {
			sharefree(sh);
			sh = NULL;
		}
		if ((sh = findentry(rpath)) == NULL &&
			(sh = find_lofsentry(rpath, &lofs_tried)) == NULL) {
			/*
			 * There is no file name entry.
			 * If the file (with symbolic links resolved) exists,
			 * the error returned should be EACCES.
			 */
			if (realpath_error == 0)
				break;
		} else if (checkrootmount(sh, rpath) == 0) {
			/*
			 * This is a "nosub" only export, in which case,
			 * mounting subdirectories isn't allowed.
			 * If the file (with symbolic links resolved) exists,
			 * the error returned should be EACCES.
			 */
			if (realpath_error == 0)
				break;
		} else {
			/*
			 * Check permissions in mount table.
			 */
			if (newopts(sh->sh_opts))
				flavor_count = getclientsflavors_new(sh, nb,
					clnames, flavor_list);
			else
				flavor_count = getclientsflavors_old(sh, nb,
					clnames, flavor_list);
			if (flavor_count != 0) {
				/*
				 * Found entry in table and
				 * client has correct permissions.
				 */
				reply_error = ENOENT;
				break;
			}
		}
		/*
		 * Check all parent directories.
		 */
		dp = strrchr(checkpath, '/');
		if (dp == NULL)
			break;
		*dp = '\0';
		if (strlen(checkpath) == 0)
			break;
		/*
		 * Get the real path (no symbolic links in it)
		 */
		if (realpath(checkpath, rpath) == NULL) {
			if (errno != ENOENT)
				break;
		} else {
			realpath_error = 0;
		}
	}

	if (sh)
		sharefree(sh);
	free(checkpath);
	return (reply_error);
}

/*
 * Check mount requests, add to mounted list if ok
 */
static void
mount(struct svc_req *rqstp)
{
	SVCXPRT *transp;
	int version, vers;
	struct fhstatus fhs;
	struct mountres3 mountres3;
	char fh[FHSIZE3];
	int len = FHSIZE3;
	char *path, rpath[MAXPATHLEN];
	struct share *sh = NULL;
	struct nd_hostservlist *clnames = NULL;
	char *host = NULL;
	int error = 0, lofs_tried = 0;
	int flavor_list[MAX_FLAVORS];
	int flavor_count;
	struct netbuf *nb;

	transp = rqstp->rq_xprt;
	version = rqstp->rq_vers;
	path = NULL;

	if (!svc_getargs(transp, xdr_dirpath, (caddr_t)&path)) {
		svcerr_decode(transp);
		return;
	}

	getclientsnames(transp, &nb, &clnames);
	if (clnames == NULL || nb == NULL) {
		/*
		 * We failed to get a name for the client, even 'anon',
		 * probably because we ran out of memory. In this situation
		 * it doesn't make sense to allow the mount to succeed.
		 */
		error = EACCES;
		goto reply;
	}
	host = clnames->h_hostservs[0].h_host;

	/*
	 * If the version being used is less than the minimum version,
	 * the filehandle translation should not be provided to the
	 * client.
	 */
	if (rejecting || version < mount_vers_min) {
		if (verbose)
			syslog(LOG_NOTICE, "Rejected mount: %s for %s",
				host, path);
		error = EACCES;
		goto reply;
	}

	/*
	 * Trusted Extension doesn't support older versions of nfs(v2, v3).
	 * To prevent circumventing TX label policy via using an older
	 * version of nfs client, reject the mount request and log an
	 * error.
	 */
	if (is_system_labeled()) {
		syslog(LOG_ERR,
		    "mount rejected: Solaris TX only supports nfs4 clients");
		error = EACCES;
		goto reply;
	}

	/*
	 * Get the real path (no symbolic links in it)
	 */
	if (realpath(path, rpath) == NULL) {
		error = errno;
		if (verbose)
			syslog(LOG_ERR,
				"mount request: realpath: %s: %m", path);
		if (error == ENOENT)
			error = mount_enoent_error(path, rpath, clnames, nb,
					flavor_list);
		goto reply;
	}

	if ((sh = findentry(rpath)) == NULL &&
		(sh = find_lofsentry(rpath, &lofs_tried)) == NULL) {
		error = EACCES;
		goto reply;
	}

	/*
	 * Check if this is a "nosub" only export, in which case, mounting
	 * subdirectories isn't allowed. Bug 1184573.
	 */
	if (checkrootmount(sh, rpath) == 0) {
		error = EACCES;
		goto reply;
	}

	if (newopts(sh->sh_opts))
		flavor_count = getclientsflavors_new(sh, nb, clnames,
					flavor_list);
	else
		flavor_count = getclientsflavors_old(sh, nb, clnames,
					flavor_list);

	if (flavor_count == 0) {
		error = EACCES;
		goto reply;
	}

	/*
	 * Now get the filehandle.
	 *
	 * NFS V2 clients get a 32 byte filehandle.
	 * NFS V3 clients get a 32 or 64 byte filehandle, depending on
	 * the embedded FIDs.
	 */
	vers = (version == MOUNTVERS3) ? NFS_V3 : NFS_VERSION;

	/* LINTED pointer alignment */
	while (nfs_getfh(rpath, vers, &len, fh) < 0) {
		if (errno == EINVAL &&
			(sh = find_lofsentry(rpath, &lofs_tried)) != NULL) {
			errno = 0;
			continue;
		}
		error = errno == EINVAL ? EACCES : errno;
		syslog(LOG_DEBUG, "mount request: getfh failed on %s: %m",
			path);
		break;
	}

	if (version == MOUNTVERS3) {
		mountres3.mountres3_u.mountinfo.fhandle.fhandle3_len = len;
		mountres3.mountres3_u.mountinfo.fhandle.fhandle3_val = fh;
	} else {
		bcopy(fh, &fhs.fhstatus_u.fhs_fhandle, NFS_FHSIZE);
	}

reply:
	switch (version) {
	case MOUNTVERS:
	case MOUNTVERS_POSIX:
		if (error == EINVAL)
			fhs.fhs_status = NFSERR_ACCES;
		else if (error == EREMOTE)
			fhs.fhs_status = NFSERR_REMOTE;
		else
			fhs.fhs_status = error;
		if (!svc_sendreply(transp, xdr_fhstatus, (char *)&fhs))
			log_cant_reply(transp);
		audit_mountd_mount(host, path, fhs.fhs_status); /* BSM */
		break;

	case MOUNTVERS3:
		if (!error) {
		mountres3.mountres3_u.mountinfo.auth_flavors.auth_flavors_val =
			flavor_list;
		mountres3.mountres3_u.mountinfo.auth_flavors.auth_flavors_len =
			flavor_count;

		} else if (error == ENAMETOOLONG)
			error = MNT3ERR_NAMETOOLONG;

		mountres3.fhs_status = error;
		if (!svc_sendreply(transp, xdr_mountres3, (char *)&mountres3))
			log_cant_reply(transp);
		audit_mountd_mount(host, path, mountres3.fhs_status); /* BSM */

		break;
	}

	if (verbose)
		syslog(LOG_NOTICE, "MOUNT: %s %s %s",
			(host == NULL) ? "unknown host" : host,
			error ? "denied" : "mounted", path);

	if (path != NULL)
		svc_freeargs(transp, xdr_dirpath, (caddr_t)&path);

	if (!error)
		mntlist_new(host, rpath); /* add entry to mount list */
done:
	if (sh)
		sharefree(sh);
	netdir_free(clnames, ND_HOSTSERVLIST);
}

struct share *
findentry(char *path)
{
	struct share *sh = NULL;
	struct sh_list *shp;
	register char *p1, *p2;
	struct stat st1;
	struct stat64 st2;

	check_sharetab();

	(void) rw_rdlock(&sharetab_lock);

	for (shp = share_list; shp; shp = shp->shl_next) {
		sh = shp->shl_sh;
		for (p1 = sh->sh_path, p2 = path; *p1 == *p2; p1++, p2++)
			if (*p1 == '\0')
				goto done;	/* exact match */

		/*
		 * Now compare the pathnames for three cases:
		 *
		 * Parent: /export/foo		(no trailing slash on parent)
		 * Child:  /export/foo/bar
		 *
		 * Parent: /export/foo/		(trailing slash on parent)
		 * Child:  /export/foo/bar
		 *
		 * Parent: /export/foo/		(no trailing slash on child)
		 * Child:  /export/foo
		 *
		 * Then compare the dev_t of the parent and child to
		 * make sure that they're both in the same filesystem.
		 */
		if ((*p1 == '\0' && *p2 == '/') ||
		    (*p1 == '\0' && *(p1-1) == '/') ||
		    (*p2 == '\0' && *p1 == '/' && *(p1+1) == '\0')) {
			if (stat(sh->sh_path, &st1) < 0) {
				if (verbose)
					syslog(LOG_NOTICE, "%s: %m", p1);
				shp = NULL;
				goto done;
			}
			/*
			 * Use stat64 on "path" since it might be larger
			 * than 2 Gb and 32 bit stat would fail EOVERFLOW
			 */
			if (stat64(path, &st2) < 0) {
				if (verbose)
					syslog(LOG_NOTICE, "%s: %m", p2);
				shp = NULL;
				goto done;
			}
			if (st1.st_dev == st2.st_dev)
				goto done;
		}
	}
done:
	sh = shp ? sharedup(sh) : NULL;

	(void) rw_unlock(&sharetab_lock);

	return (sh);
}


static int
is_substring(char **mntp, char **path)
{
	char *p1 = *mntp, *p2 = *path;

	if (*p1 == '\0' && *p2 == '\0') /* exact match */
		return (1);
	else if (*p1 == '\0' && *p2 == '/')
		return (1);
	else if (*p1 == '\0' && *(p1-1) == '/') {
		*path = --p2; /* we need the slash in p2 */
		return (1);
	} else if (*p2 == '\0') {
		while (*p1 == '/')
			p1++;
		if (*p1 == '\0') /* exact match */
			return (1);
	}
	return (0);
}

/*
 * find_lofsentry() searches for the real path which this requested LOFS path
 * (rpath) shadows. If found, it will return the sharetab entry of
 * the real path that corresponds to the LOFS path.
 * We first search mnttab to see if the requested path is an automounted
 * path. If it is an automounted path, it will trigger the mount by stat()ing
 * the requested path. Note that it is important to check that this path is
 * actually an automounted path, otherwise we would stat() a path which may
 * turn out to be NFS and block indefinitely on a dead server. The automounter
 * times-out if the server is dead, so there's no risk of hanging this
 * thread waiting for stat().
 * After the mount has been triggered (if necessary), we look for a
 * mountpoint of type LOFS (by searching /etc/mnttab again) which
 * is a substring of the rpath. If found, we construct a new path by
 * concatenating the mnt_special and the remaining of rpath, call findentry()
 * to make sure the 'real path' is shared.
 */
static struct share *
find_lofsentry(char *rpath, int *done_flag)
{
	struct stat r_stbuf;
	mntlist_t *ml, *mntl, *mntpnt = NULL;
	struct share *retcode = NULL;
	char tmp_path[MAXPATHLEN];
	int mntpnt_len = 0, tmp;
	char *p1, *p2;

	if ((*done_flag)++)
		return (retcode);

	/*
	 * While fsgetmntlist() uses lockf() to
	 * lock the mnttab before reading it in,
	 * the lock ignores threads in the same process.
	 * Read in the mnttab with the protection of a mutex.
	 */
	(void) mutex_lock(&mnttab_lock);
	mntl = fsgetmntlist();
	(void) mutex_unlock(&mnttab_lock);

	/*
	 * Obtain the mountpoint for the requested path.
	 */
	for (ml = mntl; ml; ml = ml->mntl_next) {
		for (p1 = ml->mntl_mnt->mnt_mountp, p2 = rpath;
			*p1 == *p2 && *p1; p1++, p2++);
		if (is_substring(&p1, &p2) &&
		    (tmp = strlen(ml->mntl_mnt->mnt_mountp)) >= mntpnt_len) {
			mntpnt = ml;
			mntpnt_len = tmp;
		}
	}

	/*
	 * If the path needs to be autoFS mounted, trigger the mount by
	 * stat()ing it. This is determined by checking whether the
	 * mountpoint we just found is of type autofs.
	 */
	if (mntpnt != NULL &&
	    strcmp(mntpnt->mntl_mnt->mnt_fstype, "autofs") == 0) {
		/*
		 * The requested path is a substring of an autoFS filesystem.
		 * Trigger the mount.
		 */
		if (stat(rpath, &r_stbuf) < 0) {
			if (verbose)
				syslog(LOG_NOTICE, "%s: %m", rpath);
			goto done;
		}
		if ((r_stbuf.st_mode & S_IFMT) == S_IFDIR) {
			/*
			 * The requested path is a directory, stat(2) it
			 * again with a trailing '.' to force the autoFS
			 * module to trigger the mount of indirect
			 * automount entries, such as /net/jurassic/.
			 */
			if (strlen(rpath) + 2 > MAXPATHLEN) {
				if (verbose) {
					syslog(LOG_NOTICE,
						"%s/.: exceeds MAXPATHLEN %d",
						rpath, MAXPATHLEN);
				}
				goto done;
			}
			(void) strcpy(tmp_path, rpath);
			(void) strcat(tmp_path, "/.");

			if (stat(tmp_path, &r_stbuf) < 0) {
				if (verbose)
					syslog(LOG_NOTICE, "%s: %m", tmp_path);
				goto done;
			}
		}
		/*
		 * The mount has been triggered, re-read mnttab to pick up
		 * the changes made by autoFS.
		 */
		fsfreemntlist(mntl);
		(void) mutex_lock(&mnttab_lock);
		mntl = fsgetmntlist();
		(void) mutex_unlock(&mnttab_lock);
	}

	/*
	 * The autoFS mountpoint has been triggered if necessary,
	 * now search mnttab again to determine if the requested path
	 * is an LOFS mount of a shared path.
	 */
	mntpnt_len = 0;
	for (ml = mntl; ml; ml = ml->mntl_next) {
		if (strcmp(ml->mntl_mnt->mnt_fstype, "lofs"))
			continue;

		for (p1 = ml->mntl_mnt->mnt_mountp, p2 = rpath;
				*p1 == *p2 && *p1; p1++, p2++);

		if (is_substring(&p1, &p2) &&
		    ((tmp = strlen(ml->mntl_mnt->mnt_mountp)) >= mntpnt_len)) {
			mntpnt_len = tmp;

			if ((strlen(ml->mntl_mnt->mnt_special) + strlen(p2)) >
			    MAXPATHLEN) {
				if (verbose) {
					syslog(LOG_NOTICE, "%s%s: exceeds %d",
						ml->mntl_mnt->mnt_special, p2,
						MAXPATHLEN);
				}
				if (retcode)
					sharefree(retcode);
				retcode = NULL;
				goto done;
			}

			(void) strcpy(tmp_path, ml->mntl_mnt->mnt_special);
			(void) strcat(tmp_path, p2);
			if (retcode)
				sharefree(retcode);
			retcode = findentry(tmp_path);
		}
	}

	if (retcode) {
		assert(strlen(tmp_path) > 0);
		(void) strcpy(rpath, tmp_path);
	}

done:
	fsfreemntlist(mntl);
	return (retcode);
}

/*
 * Determine whether an access list grants rights to a particular host.
 * We match on aliases of the hostname as well as on the canonical name.
 * Names in the access list may be either hosts or netgroups;  they're
 * not distinguished syntactically.  We check for hosts first because
 * it's cheaper (just M*N strcmp()s), then try netgroups.
 */
int
in_access_list(struct netbuf *nb, struct nd_hostservlist *clnames,
    char *access_list)	/* N.B. we clobber this "input" parameter */
{
	int nentries;
	char *gr;
	char *lasts;
	char *host;
	int off;
	int i;
	int netgroup_match;
	int response;

	/*
	 * If no access list - then it's unrestricted
	 */
	if (access_list == NULL || *access_list == '\0')
		return (1);

	nentries = 0;

	for (gr = strtok_r(access_list, ":", &lasts);
		gr != NULL; gr = strtok_r(NULL, ":", &lasts)) {

		/*
		 * If the list name has a '-' prepended
		 * then a match of the following name
		 * implies failure instead of success.
		 */
		if (*gr == '-') {
			response = 0;
			gr++;
		} else
			response = 1;

		/*
		 * The following loops through all the
		 * client's aliases.  Usually it's just one name.
		 */
		for (i = 0; i < clnames->h_cnt; i++) {
			host = clnames->h_hostservs[i].h_host;

			/*
			 * If the list name begins with a dot then
			 * do a domain name suffix comparison.
			 * A single dot matches any name with no
			 * suffix.
			 */
			if (*gr == '.') {
				if (*(gr + 1) == '\0') {  /* single dot */
					if (strchr(host, '.') == NULL)
						return (response);
				} else {
					off = strlen(host) - strlen(gr);
					if (off > 0 &&
					    strcasecmp(host + off, gr) == 0) {
						return (response);
					}
				}
			} else

			/*
			 * If the list name begins with an at
			 * sign then do a network comparison.
			 */
			if (*gr == '@') {
				if (netmatch(nb, gr + 1))
					return (response);
			} else

			/*
			 * Just do a hostname match
			 */
			if (strcasecmp(gr, host) == 0) {
				return (response);	/* Matched a hostname */
			}
		}

		nentries++;
	}

	netgroup_match = netgroup_check(clnames, access_list, nentries);

	return (netgroup_match);
}


int
netmatch(struct netbuf *nb, char *name)
{
	uint_t claddr;
	struct netent n, *np;
	char *mp, *p;
	uint_t addr, mask;
	int i, bits;
	char buff[256];

	/*
	 * Check if it's an IPv4 addr
	 */
	if (nb->len != sizeof (struct sockaddr_in))
		return (0);

	(void) memcpy(&claddr,
		/* LINTED pointer alignment */
		&((struct sockaddr_in *)nb->buf)->sin_addr.s_addr,
		sizeof (struct in_addr));
	claddr = ntohl(claddr);

	mp = strchr(name, '/');
	if (mp)
		*mp++ = '\0';

	if (isdigit(*name)) {
		/*
		 * Convert a dotted IP address
		 * to an IP address. The conversion
		 * is not the same as that in inet_addr().
		 */
		p = name;
		addr = 0;
		for (i = 0; i < 4; i++) {
			addr |= atoi(p) << ((3-i) * 8);
			p = strchr(p, '.');
			if (p == NULL)
				break;
			p++;
		}
	} else {
		/*
		 * Turn the netname into
		 * an IP address.
		 */
		np = getnetbyname_r(name, &n, buff, sizeof (buff));
		if (np == NULL) {
			syslog(LOG_DEBUG, "getnetbyname_r: %s: %m", name);
			return (0);
		}
		addr = np->n_net;
	}

	/*
	 * If the mask is specified explicitly then
	 * use that value, e.g.
	 *
	 *    @109.104.56/28
	 *
	 * otherwise assume a mask from the zero octets
	 * in the least significant bits of the address, e.g.
	 *
	 *   @109.104  or  @109.104.0.0
	 */
	if (mp) {
		bits = atoi(mp);
		mask = bits ? ~0 << ((sizeof (struct in_addr) * NBBY) - bits)
			: 0;
		addr &= mask;
	} else {
		if ((addr & 0x00ffffff) == 0)
			mask = 0xff000000;
		else if ((addr & 0x0000ffff) == 0)
			mask = 0xffff0000;
		else if ((addr & 0x000000ff) == 0)
			mask = 0xffffff00;
	}

	return ((claddr & mask) == addr);
}


static char *optlist[] = {
#define	OPT_RO		0
	SHOPT_RO,
#define	OPT_RW		1
	SHOPT_RW,
#define	OPT_ROOT	2
	SHOPT_ROOT,
#define	OPT_SECURE	3
	SHOPT_SECURE,
#define	OPT_ANON	4
	SHOPT_ANON,
#define	OPT_WINDOW	5
	SHOPT_WINDOW,
#define	OPT_NOSUID	6
	SHOPT_NOSUID,
#define	OPT_ACLOK	7
	SHOPT_ACLOK,
#define	OPT_SEC		8
	SHOPT_SEC,
	NULL
};

static int
map_flavor(char *str)
{
	seconfig_t sec;

	if (nfs_getseconfig_byname(str, &sec))
		return (-1);

	return (sec.sc_nfsnum);
}

/*
 * If the option string contains a "sec="
 * option, then use new option syntax.
 */
static int
newopts(char *opts)
{
	char *head, *p, *val;

	if (!opts || *opts == '\0')
		return (0);

	head = strdup(opts);
	if (head == NULL) {
		syslog(LOG_ERR, "opts: no memory");
		return (0);
	}

	p = head;
	while (*p) {
		if (getsubopt(&p, optlist, &val) == OPT_SEC) {
			free(head);
			return (1);
		}
	}

	free(head);
	return (0);
}

/*
 * Given an export and the clients hostname(s)
 * determine the security flavors that this
 * client is permitted to use.
 *
 * This routine is called only for "old" syntax, i.e.
 * only one security flavor is allowed.  So we need
 * to determine two things: the particular flavor,
 * and whether the client is allowed to use this
 * flavor, i.e. is in the access list.
 *
 * Note that if there is no access list, then the
 * default is that access is granted.
 */
static int
getclientsflavors_old(struct share *sh, struct netbuf *nb,
    struct nd_hostservlist *clnames, int *flavors)
{
	char *opts, *p, *val;
	int ok = 0;
	int defaultaccess = 1;

	opts = strdup(sh->sh_opts);
	if (opts == NULL) {
		syslog(LOG_ERR, "getclientsflavors: no memory");
		return (0);
	}

	flavors[0] = AUTH_SYS;
	p = opts;

	while (*p) {

		switch (getsubopt(&p, optlist, &val)) {
		case OPT_SECURE:
			flavors[0] = AUTH_DES;
			break;

		case OPT_RO:
		case OPT_RW:
			defaultaccess = 0;
			if (in_access_list(nb, clnames, val))
				ok++;
			break;
		}
	}

	free(opts);

	return (defaultaccess || ok);
}

/*
 * Given an export and the clients hostname(s)
 * determine the security flavors that this
 * client is permitted to use.
 *
 * This is somewhat more complicated than the "old"
 * routine because the options may contain multiple
 * security flavors (sec=) each with its own access
 * lists.  So a client could be granted access based
 * on a number of security flavors.  Note that the
 * type of access might not always be the same, the
 * client may get readonly access with one flavor
 * and readwrite with another, however the client
 * is not told this detail, it gets only the list
 * of flavors, and only if the client is using
 * version 3 of the mount protocol.
 */
static int
getclientsflavors_new(struct share *sh, struct netbuf *nb,
    struct nd_hostservlist *clnames, int *flavors)
{
	char *opts, *p, *val;
	char *lasts;
	char *f;
	int access_ok, count, c;

	opts = strdup(sh->sh_opts);
	if (opts == NULL) {
		syslog(LOG_ERR, "getclientsflavors: no memory");
		return (0);
	}

	p = opts;
	count = c = 0;
	/* default access is rw */
	access_ok = 1;

	while (*p) {
		switch (getsubopt(&p, optlist, &val)) {
		case OPT_SEC:
			/*
			 * Before a new sec=xxx option, check if we need
			 * to move the c index back to the previous count.
			 */
			if (!access_ok) {
				c = count;
			}

			/* get all the sec=f1[:f2] flavors */
			while ((f = strtok_r(val, ":", &lasts))
					!= NULL) {
				flavors[c++] = map_flavor(f);
				val = NULL;
			}
			/* for a new sec=xxx option, default is rw access */
			access_ok = 1;
			break;

		case OPT_RO:
		case OPT_RW:
			if (in_access_list(nb, clnames, val)) {
				count = c;
				access_ok = 1;
			} else {
				access_ok = 0;
			}
			break;
		}
	}

	if (!access_ok) {
		c = count;
	}
	free(opts);

	return (c);
}

/*
 * This is a tricky piece of code that parses the
 * share options looking for a match on the auth
 * flavor that the client is using. If it finds
 * a match, then the client is given ro, rw, or
 * no access depending whether it is in the access
 * list.  There is a special case for "secure"
 * flavor.  Other flavors are values of the new "sec=" option.
 */
int
check_client(struct share *sh, struct netbuf *nb,
    struct nd_hostservlist *clnames, int flavor)
{
	if (newopts(sh->sh_opts))
		return (check_client_new(sh, nb, clnames, flavor));
	else
		return (check_client_old(sh, nb, clnames, flavor));
}

static int
check_client_old(struct share *sh, struct netbuf *nb,
    struct nd_hostservlist *clnames, int flavor)
{
	char *opts, *p, *val;
	int match;	/* Set when a flavor is matched */
	int perm = 0;	/* Set when "ro", "rw" or "root" is matched */
	int list = 0;	/* Set when "ro", "rw" is found */
	int ro_val = 0;	/* Set if ro option is 'ro=' */
	int rw_val = 0;	/* Set if rw option is 'rw=' */

	opts = strdup(sh->sh_opts);
	if (opts == NULL) {
		syslog(LOG_ERR, "check_client: no memory");
		return (0);
	}

	p = opts;
	match = AUTH_UNIX;

	while (*p) {
		switch (getsubopt(&p, optlist, &val)) {

		case OPT_SECURE:
			match = AUTH_DES;
			break;

		case OPT_RO:
			list++;
			if (val) ro_val++;
			if (in_access_list(nb, clnames, val))
				perm |= NFSAUTH_RO;
			break;

		case OPT_RW:
			list++;
			if (val) rw_val++;
			if (in_access_list(nb, clnames, val))
				perm |= NFSAUTH_RW;
			break;

		case OPT_ROOT:
			/*
			 * Check if the client is in
			 * the root list. Only valid
			 * for AUTH_SYS.
			 */
			if (flavor != AUTH_SYS)
				break;

			if (val == NULL || *val == '\0')
				break;

			if (in_access_list(nb, clnames, val))
				perm |= NFSAUTH_ROOT;
			break;
		}
	}

	free(opts);

	if (flavor != match)
		return (NFSAUTH_DENIED);

	if (list) {
		/*
		 * If the client doesn't match an "ro" or "rw"
		 * list then set no access.
		 */
		if ((perm & (NFSAUTH_RO | NFSAUTH_RW)) == 0)
			perm |= NFSAUTH_DENIED;
	} else {
		/*
		 * The client matched a flavor entry that
		 * has no explicit "rw" or "ro" determination.
		 * Default it to "rw".
		 */
		perm |= NFSAUTH_RW;
	}


	/*
	 * The client may show up in both ro= and rw=
	 * lists.  If so, then turn off the RO access
	 * bit leaving RW access.
	 */
	if (perm & NFSAUTH_RO && perm & NFSAUTH_RW) {
		/*
		 * Logically cover all permutations of rw=,ro=.
		 * In the case where, rw,ro=<host> we would like
		 * to remove RW access for the host.  In all other cases
		 * RW wins the precedence battle.
		 */
		if (!rw_val && ro_val) {
			perm &= ~(NFSAUTH_RW);
		} else {
			perm &= ~(NFSAUTH_RO);
		}
	}

	return (perm);
}

/*
 * Check if the client has access by using a flavor different from
 * the given "flavor". If "flavor" is not in the flavor list,
 * return TRUE to indicate that this "flavor" is a wrong sec.
 */
static bool_t
is_wrongsec(struct share *sh, struct netbuf *nb,
		struct nd_hostservlist *clnames, int flavor)
{
	int flavor_list[MAX_FLAVORS];
	int flavor_count, i;

	/* get the flavor list that the client has access with */
	flavor_count = getclientsflavors_new(sh, nb, clnames, flavor_list);

	if (flavor_count == 0)
		return (FALSE);

	/*
	 * Check if the given "flavor" is in the flavor_list.
	 */
	for (i = 0; i < flavor_count; i++) {
		if (flavor == flavor_list[i])
			return (FALSE);
	}

	/*
	 * If "flavor" is not in the flavor_list, return TRUE to indicate
	 * that the client should have access by using a security flavor
	 * different from this "flavor".
	 */
	return (TRUE);
}

/*
 * Given an export and the client's hostname, we
 * check the security options to see whether the
 * client is allowed to use the given security flavor.
 *
 * The strategy is to proceed through the options looking
 * for a flavor match, then pay attention to the ro, rw,
 * and root options.
 *
 * Note that an entry may list several flavors in a
 * single entry, e.g.
 *
 *   sec=krb5,rw=clnt1:clnt2,ro,sec=sys,ro
 *
 */

static int
check_client_new(struct share *sh, struct netbuf *nb,
    struct nd_hostservlist *clnames, int flavor)
{
	char *opts, *p, *val;
	char *lasts;
	char *f;
	int match = 0;	/* Set when a flavor is matched */
	int perm = 0;	/* Set when "ro", "rw" or "root" is matched */
	int list = 0;	/* Set when "ro", "rw" is found */
	int ro_val = 0;	/* Set if ro option is 'ro=' */
	int rw_val = 0;	/* Set if rw option is 'rw=' */

	opts = strdup(sh->sh_opts);
	if (opts == NULL) {
		syslog(LOG_ERR, "check_client: no memory");
		return (0);
	}

	p = opts;

	while (*p) {
		switch (getsubopt(&p, optlist, &val)) {

		case OPT_SEC:
			if (match)
				goto done;

			while ((f = strtok_r(val, ":", &lasts))
					!= NULL) {
				if (flavor == map_flavor(f)) {
					match = 1;
					break;
				}
				val = NULL;
			}
			break;

		case OPT_RO:
			if (!match)
				break;

			list++;
			if (val) ro_val++;
			if (in_access_list(nb, clnames, val))
				perm |= NFSAUTH_RO;
			break;

		case OPT_RW:
			if (!match)
				break;

			list++;
			if (val) rw_val++;
			if (in_access_list(nb, clnames, val))
				perm |= NFSAUTH_RW;
			break;

		case OPT_ROOT:
			/*
			 * Check if the client is in
			 * the root list. Only valid
			 * for AUTH_SYS.
			 */
			if (flavor != AUTH_SYS)
				break;

			if (!match)
				break;

			if (val == NULL || *val == '\0')
				break;

			if (in_access_list(nb, clnames, val))
				perm |= NFSAUTH_ROOT;
			break;
		}
	}

done:
	/*
	 * If no match then set the perm accordingly
	 */
	if (!match)
		return (NFSAUTH_DENIED);

	if (list) {
		/*
		 * If the client doesn't match an "ro" or "rw" list then
		 * check if it may have access by using a different flavor.
		 * If so, return NFSAUTH_WRONGSEC.
		 * If not, return NFSAUTH_DENIED.
		 */
		if ((perm & (NFSAUTH_RO | NFSAUTH_RW)) == 0) {
			if (is_wrongsec(sh, nb, clnames, flavor))
				perm |= NFSAUTH_WRONGSEC;
			else
				perm |= NFSAUTH_DENIED;
		}
	} else {
		/*
		 * The client matched a flavor entry that
		 * has no explicit "rw" or "ro" determination.
		 * Make sure it defaults to "rw".
		 */
		perm |= NFSAUTH_RW;
	}

	/*
	 * The client may show up in both ro= and rw=
	 * lists.  If so, then turn off the RO access
	 * bit leaving RW access.
	 */
	if (perm & NFSAUTH_RO && perm & NFSAUTH_RW) {
		/*
		 * Logically cover all permutations of rw=,ro=.
		 * In the case where, rw,ro=<host> we would like
		 * to remove RW access for the host.  In all other cases
		 * RW wins the precedence battle.
		 */
		if (!rw_val && ro_val) {
			perm &= ~(NFSAUTH_RW);
		} else {
			perm &= ~(NFSAUTH_RO);
		}
	}

	free(opts);

	return (perm);
}

void
check_sharetab()
{
	FILE *f;
	struct stat st;
	static timestruc_t last_sharetab_time;
	timestruc_t prev_sharetab_time;
	struct share *sh;
	struct sh_list *shp, *shp_prev;
	int res, c = 0;

	/*
	 *  read in /etc/dfs/sharetab if it has changed
	 */

	if (stat(SHARETAB, &st) != 0) {
		syslog(LOG_ERR, "Cannot stat %s: %m", SHARETAB);
		return;
	}

	if (st.st_mtim.tv_sec == last_sharetab_time.tv_sec &&
	    st.st_mtim.tv_nsec == last_sharetab_time.tv_nsec) {
		/*
		 * No change.
		 */
		return;
	}

	/*
	 * Remember the mod time, then after getting the
	 * write lock check again.  If another thread
	 * already did the update, then there's no
	 * work to do.
	 */
	prev_sharetab_time = last_sharetab_time;

	(void) rw_wrlock(&sharetab_lock);

	if (prev_sharetab_time.tv_sec != last_sharetab_time.tv_sec ||
	    prev_sharetab_time.tv_nsec != last_sharetab_time.tv_nsec) {
		(void) rw_unlock(&sharetab_lock);
		return;
	}

	f = fopen(SHARETAB, "r+");
	if (f == NULL) {
		syslog(LOG_ERR, "Cannot open %s: %m", SHARETAB);
		(void) rw_unlock(&sharetab_lock);
		return;
	}

	/*
	 * Lock the file so that unshare can't
	 * truncate it while we're reading
	 */
	if (lockf(fileno(f), F_LOCK, 0L) < 0) {
		syslog(LOG_ERR, "Cannot lock %s: %m", SHARETAB);
		(void) rw_unlock(&sharetab_lock);
		(void) fclose(f);
		return;
	}

	/*
	 * Once we are sure /etc/dfs/sharetab has been
	 * modified, flush netgroup cache entries.
	 */
	netgrp_cache_flush();

	sh_free(share_list);			/* free old list */
	share_list = NULL;

	while ((res = getshare(f, &sh)) > 0) {
		c++;
		if (strcmp(sh->sh_fstype, "nfs") != 0)
			continue;

		shp = malloc(sizeof (*shp));
		if (shp == NULL)
			goto alloc_failed;
		if (share_list == NULL)
			share_list = shp;
		else
			/* LINTED not used before set */
			shp_prev->shl_next = shp;
		shp_prev = shp;
		shp->shl_next = NULL;
		shp->shl_sh = sharedup(sh);
		if (shp->shl_sh == NULL)
			goto alloc_failed;
	}
	if (res < 0)
		syslog(LOG_ERR, "%s: invalid at line %d\n",
			SHARETAB, c + 1);

	if (stat(SHARETAB, &st) != 0) {
		syslog(LOG_ERR, "Cannot stat %s: %m", SHARETAB);
		(void) rw_unlock(&sharetab_lock);
		return;
	}
	last_sharetab_time = st.st_mtim;
	(void) fclose(f);
	(void) rw_unlock(&sharetab_lock);
	return;

alloc_failed:
	syslog(LOG_ERR, "check_sharetab: no memory");
	sh_free(share_list);
	share_list = NULL;
	(void) fclose(f);
	(void) rw_unlock(&sharetab_lock);
}

static void
sh_free(struct sh_list *shp)
{
	register struct sh_list *next;

	while (shp) {
		sharefree(shp->shl_sh);
		next = shp->shl_next;
		free(shp);
		shp = next;
	}
}


/*
 * Remove an entry from mounted list
 */
static void
umount(struct svc_req *rqstp)
{
	char *host, *path, *remove_path;
	char rpath[MAXPATHLEN];
	struct nd_hostservlist *clnames = NULL;
	SVCXPRT *transp;
	struct netbuf *nb;

	transp = rqstp->rq_xprt;
	path = NULL;
	if (!svc_getargs(transp, xdr_dirpath, (caddr_t)&path)) {
		svcerr_decode(transp);
		return;
	}
	errno = 0;
	if (!svc_sendreply(transp, xdr_void, (char *)NULL))
		log_cant_reply(transp);

	getclientsnames(transp, &nb, &clnames);
	if (clnames == NULL) {
		/*
		 * Without the hostname we can't do audit or delete
		 * this host from the mount entries.
		 */
		svc_freeargs(transp, xdr_dirpath, (caddr_t)&path);
		return;
	}
	host = clnames->h_hostservs[0].h_host;

	if (verbose)
		syslog(LOG_NOTICE, "UNMOUNT: %s unmounted %s", host, path);

	audit_mountd_umount(host, path);

	remove_path = rpath;	/* assume we will use the cannonical path */
	if (realpath(path, rpath) == NULL) {
		if (verbose)
			syslog(LOG_WARNING, "UNMOUNT: realpath: %s: %m ", path);
		remove_path = path;	/* use path provided instead */
	}

	mntlist_delete(host, remove_path);	/* remove from mount list */

	svc_freeargs(transp, xdr_dirpath, (caddr_t)&path);
	netdir_free(clnames, ND_HOSTSERVLIST);
}

/*
 * Remove all entries for one machine from mounted list
 */
static void
umountall(struct svc_req *rqstp)
{
	struct nd_hostservlist *clnames = NULL;
	SVCXPRT *transp;
	char *host;
	struct netbuf *nb;

	transp = rqstp->rq_xprt;
	if (!svc_getargs(transp, xdr_void, NULL)) {
		svcerr_decode(transp);
		return;
	}
	/*
	 * We assume that this call is asynchronous and made via rpcbind
	 * callit routine.  Therefore return control immediately. The error
	 * causes rpcbind to remain silent, as opposed to every machine
	 * on the net blasting the requester with a response.
	 */
	svcerr_systemerr(transp);
	getclientsnames(transp, &nb, &clnames);
	if (clnames == NULL) {
		/* Can't do anything without the name of the client */
		return;
	}

	host = clnames->h_hostservs[0].h_host;

	/*
	 * Remove all hosts entries from mount list
	 */
	mntlist_delete_all(host);

	if (verbose)
		syslog(LOG_NOTICE, "UNMOUNTALL: from %s", host);

	netdir_free(clnames, ND_HOSTSERVLIST);
}

void *
exmalloc(size_t size)
{
	void *ret;

	if ((ret = malloc(size)) == NULL) {
		syslog(LOG_ERR, "Out of memory");
		exit(1);
	}
	return (ret);
}

static void
sigexit(int signum)
{

	if (signum == SIGHUP)
		_exit(0);
	_exit(1);
}