go back to running these as root from inetd. however once rpc.{rusersd,rstatd}

starts, do a chroot to /var/empty and change to user nobody.
hi mom, i'm in jail!

5 files changed, 158 insertions, 146 deletions

diff --git a/etc/inetd.conf b/etc/inetd.conf
index 0c29c4e99e2..2c8793c1cb7 100644
--- a/etc/inetd.conf
+++ b/etc/inetd.conf
@@ -1,4 +1,4 @@
-#	$OpenBSD: inetd.conf,v 1.47 2002/06/05 21:48:14 deraadt Exp $
+#	$OpenBSD: inetd.conf,v 1.48 2002/06/28 22:40:31 deraadt Exp $
 #
 # Internet server configuration database
 #
@@ -51,8 +51,8 @@ time		stream	tcp6	nowait	root	internal
 # Encrypted X connections
 #kx		stream	tcp	nowait	root	/usr/X11R6/bin/kxd	kxd
 # RPC based services
-rstatd/1-3	dgram	rpc/udp	wait	nobody	/usr/libexec/rpc.rstatd	rpc.rstatd
-rusersd/1-3	dgram	rpc/udp	wait	nobody	/usr/libexec/rpc.rusersd rpc.rusersd
+rstatd/1-3	dgram	rpc/udp	wait	root	/usr/libexec/rpc.rstatd	rpc.rstatd
+rusersd/1-3	dgram	rpc/udp	wait	root	/usr/libexec/rpc.rusersd rpc.rusersd
 #walld/1	dgram	rpc/udp	wait	root	/usr/libexec/rpc.rwalld	rpc.rwalld
 #sprayd/1	dgram	rpc/udp	wait	root	/usr/libexec/rpc.sprayd	rpc.sprayd
 #rquotad/1	dgram	rpc/udp	wait	root	/usr/libexec/rpc.rquotad rpc.rquotad
diff --git a/libexec/rpc.rstatd/rstat_proc.c b/libexec/rpc.rstatd/rstat_proc.c
index 0ae365812eb..ba422ec5229 100644
--- a/libexec/rpc.rstatd/rstat_proc.c
+++ b/libexec/rpc.rstatd/rstat_proc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rstat_proc.c,v 1.21 2002/02/16 21:27:31 millert Exp $	*/
+/*	$OpenBSD: rstat_proc.c,v 1.22 2002/06/28 22:40:33 deraadt Exp $	*/
 
 /*
  * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
@@ -31,7 +31,7 @@
 #ifndef lint
 /*static char sccsid[] = "from: @(#)rpc.rstatd.c 1.1 86/09/25 Copyr 1984 Sun Micro";*/
 /*static char sccsid[] = "from: @(#)rstat_proc.c	2.2 88/08/01 4.0 RPCSRC";*/
-static char rcsid[] = "$OpenBSD: rstat_proc.c,v 1.21 2002/02/16 21:27:31 millert Exp $";
+static char rcsid[] = "$OpenBSD: rstat_proc.c,v 1.22 2002/06/28 22:40:33 deraadt Exp $";
 #endif
 
 /*
@@ -100,7 +100,7 @@ static int stat_is_init = 0;
 #endif
 
 void
-stat_init()
+stat_init(void)
 {
 	stat_is_init = 1;
 	setup();
@@ -110,9 +110,7 @@ stat_init()
 }
 
 statstime *
-rstatproc_stats_3_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rstatproc_stats_3_svc(void *arg, struct svc_req *rqstp)
 {
 	if (!stat_is_init)
 		stat_init();
@@ -121,9 +119,7 @@ rstatproc_stats_3_svc(arg, rqstp)
 }
 
 statsswtch *
-rstatproc_stats_2_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rstatproc_stats_2_svc(void *arg, struct svc_req *rqstp)
 {
 	if (!stat_is_init)
 		stat_init();
@@ -132,9 +128,7 @@ rstatproc_stats_2_svc(arg, rqstp)
 }
 
 stats *
-rstatproc_stats_1_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rstatproc_stats_1_svc(void *arg, struct svc_req *rqstp)
 {
 	if (!stat_is_init)
 		stat_init();
@@ -143,9 +137,7 @@ rstatproc_stats_1_svc(arg, rqstp)
 }
 
 u_int *
-rstatproc_havedisk_3_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rstatproc_havedisk_3_svc(void *arg, struct svc_req *rqstp)
 {
 	static u_int have;
 
@@ -157,17 +149,13 @@ rstatproc_havedisk_3_svc(arg, rqstp)
 }
 
 u_int *
-rstatproc_havedisk_2_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rstatproc_havedisk_2_svc(void *arg, struct svc_req *rqstp)
 {
 	return (rstatproc_havedisk_3_svc(arg, rqstp));
 }
 
 u_int *
-rstatproc_havedisk_1_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rstatproc_havedisk_1_svc(void *arg, struct svc_req *rqstp)
 {
 	return (rstatproc_havedisk_3_svc(arg, rqstp));
 }
@@ -179,7 +167,7 @@ updatestatsig(int sig)
 }
 
 void
-updatestat()
+updatestat(void)
 {
 	int i, mib[2], save_errno = errno;
 	struct uvmexp uvmexp;
@@ -283,22 +271,20 @@ updatestat()
 }
 
 void
-setup()
+setup(void)
 {
 	dkinit(0);
 }
 
 void
-rstat_service(rqstp, transp)
-	struct svc_req *rqstp;
-	SVCXPRT *transp;
+rstat_service(struct svc_req *rqstp, SVCXPRT *transp)
 {
+	char *(*local)(void *, struct svc_req *);
+	xdrproc_t xdr_argument, xdr_result;
 	union {
 		int fill;
 	} argument;
 	char *result;
-	xdrproc_t xdr_argument, xdr_result;
-	char *(*local)(void *, struct svc_req *);
 
 	switch (rqstp->rq_proc) {
 	case NULLPROC:
diff --git a/libexec/rpc.rstatd/rstatd.c b/libexec/rpc.rstatd/rstatd.c
index 863f219d92d..194e535d9c2 100644
--- a/libexec/rpc.rstatd/rstatd.c
+++ b/libexec/rpc.rstatd/rstatd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rstatd.c,v 1.9 2002/03/24 04:39:38 deraadt Exp $	*/
+/*	$OpenBSD: rstatd.c,v 1.10 2002/06/28 22:40:33 deraadt Exp $	*/
 
 /*-
  * Copyright (c) 1993, John Brezak
@@ -34,7 +34,7 @@
  */
 
 #ifndef lint
-static char rcsid[] = "$OpenBSD: rstatd.c,v 1.9 2002/03/24 04:39:38 deraadt Exp $";
+static char rcsid[] = "$OpenBSD: rstatd.c,v 1.10 2002/06/28 22:40:33 deraadt Exp $";
 #endif /* not lint */
 
 #include <sys/types.h>
@@ -44,6 +44,7 @@ static char rcsid[] = "$OpenBSD: rstatd.c,v 1.9 2002/03/24 04:39:38 deraadt Exp
 #include <string.h>
 #include <unistd.h>
 #include <signal.h>
+#include <pwd.h>
 #include <syslog.h>
 #include <errno.h>
 #include <stdlib.h>
@@ -60,8 +61,17 @@ void my_svc_run(void);
 int from_inetd = 1;     /* started from inetd ? */
 int closedown = 20;	/* how long to wait before going dormant */
 
+volatile sig_atomic_t gotsig;
+
+void
+getsig(int signo)
+{
+	gotsig = 1;
+}
+
+
 void
-cleanup()
+cleanup(void)
 {
 	(void) pmap_unset(RSTATPROG, RSTATVERS_TIME);	/* XXX signal races */
 	(void) pmap_unset(RSTATPROG, RSTATVERS_SWTCH);
@@ -70,14 +80,28 @@ cleanup()
 }
 
 int
-main(argc, argv)
-	int argc;
-	char *argv[];
+main(int argc, char *argv[])
 {
 	int sock = 0, proto = 0, fromlen;
+	struct passwd *pw;
 	struct sockaddr_in from;
 	SVCXPRT *transp;
 
+	pw = getpwnam("nobody");
+	if (chroot("/var/empty") == -1) {
+		syslog(LOG_ERR, "cannot chdir to /var/empty.");
+		exit(1);
+	}
+	chdir("/");
+
+	if (pw) {
+		setgroups(1, &pw->pw_gid);
+		setegid(pw->pw_gid);
+		setgid(pw->pw_gid);
+		seteuid(pw->pw_uid);
+		setegid(pw->pw_uid);
+	}
+
 	if (argc == 2)
 		closedown = atoi(argv[1]);
 	if (closedown <= 0)
@@ -100,9 +124,9 @@ main(argc, argv)
 		(void)pmap_unset(RSTATPROG, RSTATVERS_SWTCH);
 		(void)pmap_unset(RSTATPROG, RSTATVERS_ORIG);
 
-		(void) signal(SIGINT, cleanup);
-		(void) signal(SIGTERM, cleanup);
-		(void) signal(SIGHUP, cleanup);
+		(void) signal(SIGINT, getsig);
+		(void) signal(SIGTERM, getsig);
+		(void) signal(SIGHUP, getsig);
 	}
 
 	openlog("rpc.rstatd", LOG_CONS|LOG_PID, LOG_DAEMON);
@@ -131,7 +155,7 @@ main(argc, argv)
 }
 
 void
-my_svc_run()
+my_svc_run(void)
 {
 	extern volatile sig_atomic_t wantupdatestat;
 	extern void updatestat(void);
@@ -142,6 +166,8 @@ my_svc_run()
 			updatestat();
 			wantupdatestat = 0;
 		}
+		if (gotsig)
+			cleanup();
 
 		if (__svc_fdset) {
 			int bytes = howmany(__svc_fdsetsize, NFDBITS) *
diff --git a/libexec/rpc.rusersd/rusers_proc.c b/libexec/rpc.rusersd/rusers_proc.c
index 0bfabdcb893..ecf0deeb7a4 100644
--- a/libexec/rpc.rusersd/rusers_proc.c
+++ b/libexec/rpc.rusersd/rusers_proc.c
@@ -1,9 +1,9 @@
-/*	$OpenBSD: rusers_proc.c,v 1.15 2002/06/09 04:06:42 deraadt Exp $	*/
+/*	$OpenBSD: rusers_proc.c,v 1.16 2002/06/28 22:40:33 deraadt Exp $	*/
 
 /*-
  *  Copyright (c) 1993 John Brezak
  *  All rights reserved.
- * 
+ *
  *  Redistribution and use in source and binary forms, with or without
  *  modification, are permitted provided that the following conditions
  *  are met:
@@ -14,7 +14,7 @@
  *     documentation and/or other materials provided with the distribution.
  *  3. The name of the author may not be used to endorse or promote products
  *     derived from this software without specific prior written permission.
- * 
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `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
@@ -29,7 +29,7 @@
  */
 
 #ifndef lint
-static char rcsid[] = "$OpenBSD: rusers_proc.c,v 1.15 2002/06/09 04:06:42 deraadt Exp $";
+static char rcsid[] = "$OpenBSD: rusers_proc.c,v 1.16 2002/06/28 22:40:33 deraadt Exp $";
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -40,16 +40,13 @@ static char rcsid[] = "$OpenBSD: rusers_proc.c,v 1.15 2002/06/09 04:06:42 deraad
 #include <utmp.h>
 #include <stdio.h>
 #include <syslog.h>
+#include <unistd.h>
 #include <string.h>
 #include <rpc/rpc.h>
 #include <rpcsvc/rusers.h>	/* New version */
 #include <rpcsvc/rnusers.h>	/* Old version */
 
-#define	IGNOREUSER	"sleeper"
-
-#ifndef _PATH_UTMP
-#define _PATH_UTMP "/etc/utmp"
-#endif
+extern int utmp_fd;
 
 #ifndef _PATH_DEV
 #define _PATH_DEV "/dev"
@@ -83,14 +80,13 @@ extern int from_inetd;
 FILE *ufp;
 
 static u_int
-getidle(tty, display)
-	char *tty, *display;
+getidle(char *tty, char *display)
 {
-	struct stat st;
 	char devname[PATH_MAX];
-	time_t now;
+	struct stat st;
 	u_long idle;
-	
+	time_t now;
+
 	/*
 	 * If this is an X terminal or console, then try the
 	 * XIdle extension
@@ -128,16 +124,21 @@ getidle(tty, display)
 
 	return (idle);
 }
-	
+
 int *
-rusers_num_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rusers_num_svc(void *arg, struct svc_req *rqstp)
 {
 	static int num_users = 0;
 	struct utmp usr;
+	int fd;
 
-	ufp = fopen(_PATH_UTMP, "r");
+	fd = dup(utmp_fd);
+	if (fd == -1) {
+		syslog(LOG_ERR, "%m");
+		return (0);
+	}
+	lseek(fd, SEEK_SET, 0);
+	ufp = fdopen(fd, "r");
 	if (!ufp) {
 		syslog(LOG_ERR, "%m");
 		return (0);
@@ -145,15 +146,8 @@ rusers_num_svc(arg, rqstp)
 
 	/* only entries with both name and line fields */
 	while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1)
-		if (*usr.ut_name && *usr.ut_line &&
-		    strncmp(usr.ut_name, IGNOREUSER,
-			    sizeof(usr.ut_name))
-#ifdef USER_PROCESS
-		    && usr.ut_type == USER_PROCESS
-#endif
-		    ) {
+		if (*usr.ut_name && *usr.ut_line)
 			num_users++;
-		}
 
 	fclose(ufp);
 	return (&num_users);
@@ -165,11 +159,18 @@ do_names_3(int all)
 	static utmp_array ut;
 	struct utmp usr;
 	int nusers = 0;
-	
+	int fd;
+
 	bzero((char *)&ut, sizeof(ut));
 	ut.utmp_array_val = &utmps[0];
-	
-	ufp = fopen(_PATH_UTMP, "r");
+
+	fd = dup(utmp_fd);
+	if (fd == -1) {
+		syslog(LOG_ERR, "%m");
+		return (0);
+	}
+	lseek(fd, SEEK_SET, 0);
+	ufp = fdopen(fd, "r");
 	if (!ufp) {
 		syslog(LOG_ERR, "%m");
 		return (NULL);
@@ -177,19 +178,11 @@ do_names_3(int all)
 
 	/* only entries with both name and line fields */
 	while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1 &&
-	       nusers < MAXUSERS)
-		if (*usr.ut_name && *usr.ut_line &&
-		    strncmp(usr.ut_name, IGNOREUSER,
-			    sizeof(usr.ut_name))
-#ifdef USER_PROCESS
-		    && usr.ut_type == USER_PROCESS
-#endif
-		    ) {
+	    nusers < MAXUSERS)
+		if (*usr.ut_name && *usr.ut_line) {
 			utmps[nusers].ut_type = RUSERS_USER_PROCESS;
-			utmps[nusers].ut_time =
-				usr.ut_time;
-			utmps[nusers].ut_idle =
-				getidle(usr.ut_line, usr.ut_host);
+			utmps[nusers].ut_time = usr.ut_time;
+			utmps[nusers].ut_idle = getidle(usr.ut_line, usr.ut_host);
 			utmps[nusers].ut_line = line[nusers];
 			memset(line[nusers], 0, sizeof(line[nusers]));
 			strlcpy(line[nusers], usr.ut_line, sizeof(line[nusers]));
@@ -208,17 +201,13 @@ do_names_3(int all)
 }
 
 utmp_array *
-rusersproc_names_3_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rusersproc_names_3_svc(void *arg, struct svc_req *rqstp)
 {
 	return (do_names_3(0));
 }
 
 utmp_array *
-rusersproc_allnames_3_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rusersproc_allnames_3_svc(void *arg, struct svc_req *rqstp)
 {
 	return (do_names_3(1));
 }
@@ -229,12 +218,19 @@ do_names_2(int all)
 	static struct utmpidlearr ut;
 	struct utmp usr;
 	int nusers = 0;
-	
+	int fd;
+
 	bzero((char *)&ut, sizeof(ut));
 	ut.uia_arr = utmp_idlep;
 	ut.uia_cnt = 0;
-	
-	ufp = fopen(_PATH_UTMP, "r");
+
+	fd = dup(utmp_fd);
+	if (fd == -1) {
+		syslog(LOG_ERR, "%m");
+		return (0);
+	}
+	lseek(fd, SEEK_SET, 0);
+	ufp = fdopen(fd, "r");
 	if (!ufp) {
 		syslog(LOG_ERR, "%m");
 		return (NULL);
@@ -242,19 +238,11 @@ do_names_2(int all)
 
 	/* only entries with both name and line fields */
 	while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1 &&
-	       nusers < MAXUSERS)
-		if (*usr.ut_name && *usr.ut_line &&
-		    strncmp(usr.ut_name, IGNOREUSER,
-			    sizeof(usr.ut_name))
-#ifdef USER_PROCESS
-		    && usr.ut_type == USER_PROCESS
-#endif
-		    ) {
+	    nusers < MAXUSERS)
+		if (*usr.ut_name && *usr.ut_line) {
 			utmp_idlep[nusers] = &utmp_idle[nusers];
-			utmp_idle[nusers].ui_utmp.ut_time =
-				usr.ut_time;
-			utmp_idle[nusers].ui_idle =
-				getidle(usr.ut_line, usr.ut_host);
+			utmp_idle[nusers].ui_utmp.ut_time = usr.ut_time;
+			utmp_idle[nusers].ui_idle = getidle(usr.ut_line, usr.ut_host);
 			utmp_idle[nusers].ui_utmp.ut_line = line[nusers];
 			memset(line[nusers], 0, sizeof(line[nusers]));
 			strlcpy(line[nusers], usr.ut_line, sizeof(line[nusers]));
@@ -273,17 +261,13 @@ do_names_2(int all)
 }
 
 struct utmpidlearr *
-rusersproc_names_2_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rusersproc_names_2_svc(void *arg, struct svc_req *rqstp)
 {
 	return (do_names_2(0));
 }
 
 struct utmpidlearr *
-rusersproc_allnames_2_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rusersproc_allnames_2_svc(void *arg, struct svc_req *rqstp)
 {
 	return (do_names_2(1));
 }
@@ -294,12 +278,19 @@ do_names_1(int all)
 	static struct utmparr ut;
 	struct utmp usr;
 	int nusers = 0;
-	
+	int fd;
+
 	bzero((char *)&ut, sizeof(ut));
 	ut.uta_arr = ru_utmpp;
 	ut.uta_cnt = 0;
-	
-	ufp = fopen(_PATH_UTMP, "r");
+
+	fd = dup(utmp_fd);
+	if (fd == -1) {
+		syslog(LOG_ERR, "%m");
+		return (0);
+	}
+	lseek(fd, SEEK_SET, 0);
+	ufp = fdopen(fd, "r");
 	if (!ufp) {
 		syslog(LOG_ERR, "%m");
 		return (NULL);
@@ -307,14 +298,8 @@ do_names_1(int all)
 
 	/* only entries with both name and line fields */
 	while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1 &&
-	       nusers < MAXUSERS)
-		if (*usr.ut_name && *usr.ut_line &&
-		    strncmp(usr.ut_name, IGNOREUSER,
-			    sizeof(usr.ut_name))
-#ifdef USER_PROCESS
-		    && usr.ut_type == USER_PROCESS
-#endif
-		    ) {
+	    nusers < MAXUSERS)
+		if (*usr.ut_name && *usr.ut_line) {
 			ru_utmpp[nusers] = &ru_utmp[nusers];
 			ru_utmp[nusers].ut_time = usr.ut_time;
 			ru_utmp[nusers].ut_line = line[nusers];
@@ -332,32 +317,26 @@ do_names_1(int all)
 }
 
 struct utmparr *
-rusersproc_names_1_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rusersproc_names_1_svc(void *arg, struct svc_req *rqstp)
 {
 	return (do_names_1(0));
 }
 
 struct utmparr *
-rusersproc_allnames_1_svc(arg, rqstp)
-	void *arg;
-	struct svc_req *rqstp;
+rusersproc_allnames_1_svc(void *arg, struct svc_req *rqstp)
 {
 	return (do_names_1(1));
 }
 
 void
-rusers_service(rqstp, transp)
-	struct svc_req *rqstp;
-	SVCXPRT *transp;
+rusers_service(struct svc_req *rqstp, SVCXPRT *transp)
 {
+	char *(*local)(void *, struct svc_req *);
+	xdrproc_t xdr_argument, xdr_result;
 	union {
 		int fill;
 	} argument;
 	char *result;
-	xdrproc_t xdr_argument, xdr_result;
-	char *(*local)(void *, struct svc_req *);
 
 	switch (rqstp->rq_proc) {
 	case NULLPROC:
diff --git a/libexec/rpc.rusersd/rusersd.c b/libexec/rpc.rusersd/rusersd.c
index 559d83f0d09..00c60594683 100644
--- a/libexec/rpc.rusersd/rusersd.c
+++ b/libexec/rpc.rusersd/rusersd.c
@@ -1,9 +1,9 @@
-/*	$OpenBSD: rusersd.c,v 1.6 2002/06/09 04:06:42 deraadt Exp $	*/
+/*	$OpenBSD: rusersd.c,v 1.7 2002/06/28 22:40:33 deraadt Exp $	*/
 
 /*-
  *  Copyright (c) 1993 John Brezak
  *  All rights reserved.
- * 
+ *
  *  Redistribution and use in source and binary forms, with or without
  *  modification, are permitted provided that the following conditions
  *  are met:
@@ -14,7 +14,7 @@
  *     documentation and/or other materials provided with the distribution.
  *  3. The name of the author may not be used to endorse or promote products
  *     derived from this software without specific prior written permission.
- * 
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `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
@@ -29,27 +29,31 @@
  */
 
 #ifndef lint
-static char rcsid[] = "$OpenBSD: rusersd.c,v 1.6 2002/06/09 04:06:42 deraadt Exp $";
+static char rcsid[] = "$OpenBSD: rusersd.c,v 1.7 2002/06/28 22:40:33 deraadt Exp $";
 #endif /* not lint */
 
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <sys/file.h>
 #include <stdio.h>
 #include <signal.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <pwd.h>
 #include <syslog.h>
 #include <rpc/rpc.h>
 #include <rpcsvc/rusers.h>	/* New version */
 #include <rpcsvc/rnusers.h>	/* Old version */
 #include <rpc/pmap_clnt.h>
+#include <utmp.h>
 
 extern void rusers_service(struct svc_req *, SVCXPRT *);
 
 int from_inetd = 1;
+int utmp_fd;
 
 void
-cleanup()
+cleanup(int signo)
 {
 	(void) pmap_unset(RUSERSPROG, RUSERSVERS_3);	/* XXX signal races */
 	(void) pmap_unset(RUSERSPROG, RUSERSVERS_IDLE);
@@ -58,15 +62,32 @@ cleanup()
 }
 
 int
-main(argc, argv)
-	int argc;
-	char *argv[];
+main(int argc, char *argv[])
 {
-	SVCXPRT *transp;
-	int sock = 0;
-	int proto = 0;
+	int sock = 0, proto = 0, fromlen;
 	struct sockaddr_in from;
-	int fromlen;
+	struct passwd *pw;
+	SVCXPRT *transp;
+
+	if (utmp_fd = open(_PATH_UTMP, O_RDONLY) == -1) {
+		syslog(LOG_ERR, "cannot open %s", _PATH_UTMP);
+		exit(1);
+	}
+
+	pw = getpwnam("nobody");
+	if (chroot("/var/empty") == -1) {
+		syslog(LOG_ERR, "cannot chdir to /var/empty.");
+		exit(1);
+	}
+	chdir("/");
+
+	if (pw) {
+		setgroups(1, &pw->pw_gid);
+		setegid(pw->pw_gid);
+		setgid(pw->pw_gid);
+		seteuid(pw->pw_uid);
+		setegid(pw->pw_uid);
+	}
 
 	/*
 	 * See if inetd started us
@@ -77,7 +98,7 @@ main(argc, argv)
 		sock = RPC_ANYSOCK;
 		proto = IPPROTO_UDP;
 	}
-	
+
 	if (!from_inetd) {
 		daemon(0, 0);
 
@@ -91,7 +112,7 @@ main(argc, argv)
 	}
 
 	openlog("rpc.rusersd", LOG_CONS|LOG_PID, LOG_DAEMON);
-	
+
 	transp = svcudp_create(sock);
 	if (transp == NULL) {
 		syslog(LOG_ERR, "cannot create udp service.");