Remove rexecd(8), a server that implements a particularly insecure

method of executing commands remotely.  There are no rexec clients in
the FreeBSD tree, and the client function rexec(3) is present only in
libcompat.  It has been documented as "obsolete" since 4.3BSD, and its
use has been discouraged in the man page for over 10 years.

4 files changed, 0 insertions, 509 deletions

diff --git a/libexec/Makefile b/libexec/Makefile
index 0d320d7..30a8db1 100644
--- a/libexec/Makefile
+++ b/libexec/Makefile
@@ -16,7 +16,6 @@ SUBDIR=	atrun \
 	pt_chown \
 	rbootd \
 	revnetgroup \
-	${_rexecd} \
 	${_rlogind} \
 	rpc.rquotad \
 	rpc.rstatd \
@@ -47,7 +46,6 @@ _rtld-elf=	rtld-elf
 .endif
 
 .if !defined(NO_RCMDS)
-_rexecd=	rexecd
 _rlogind=	rlogind
 _rshd=		rshd
 .endif
diff --git a/libexec/rexecd/Makefile b/libexec/rexecd/Makefile
deleted file mode 100644
index 05b003e..0000000
--- a/libexec/rexecd/Makefile
+++ /dev/null
@@ -1,12 +0,0 @@
-#	@(#)Makefile	8.1 (Berkeley) 6/4/93
-# $FreeBSD$
-
-PROG=	rexecd
-MAN=	rexecd.8
-WARNS?=	6
-WFORMAT=0
-
-DPADD=  ${LIBPAM} ${LIBUTIL}
-LDADD=	${MINUSLPAM} -lutil
-
-.include <bsd.prog.mk>
diff --git a/libexec/rexecd/rexecd.8 b/libexec/rexecd/rexecd.8
deleted file mode 100644
index c2588cb..0000000
--- a/libexec/rexecd/rexecd.8
+++ /dev/null
@@ -1,169 +0,0 @@
-.\" Copyright (c) 1983, 1991, 1993
-.\"	The Regents of the University of California.  All rights reserved.
-.\"
-.\" Redistribution and use in source and binary forms, with or without
-.\" modification, are permitted provided that the following conditions
-.\" are met:
-.\" 1. Redistributions of source code must retain the above copyright
-.\"    notice, this list of conditions and the following disclaimer.
-.\" 2. Redistributions in binary form must reproduce the above copyright
-.\"    notice, this list of conditions and the following disclaimer in the
-.\"    documentation and/or other materials provided with the distribution.
-.\" 3. 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.
-.\"
-.\"     @(#)rexecd.8	8.2 (Berkeley) 12/11/93
-.\" $FreeBSD$
-.\"
-.Dd September 23, 1994
-.Dt REXECD 8
-.Os
-.Sh NAME
-.Nm rexecd
-.Nd remote execution server
-.Sh SYNOPSIS
-.Nm
-.Op Fl i
-.Sh DESCRIPTION
-The
-.Nm
-utility is the server for the
-.Xr rexec 3
-routine.
-The server provides remote execution facilities
-with authentication based on user names and
-passwords.
-.Pp
-The
-.Nm
-utility listens for service requests at the port indicated in
-the ``exec'' service specification; see
-.Xr services 5 .
-When a service request is received the following protocol
-is initiated:
-.Bl -enum
-.It
-The server reads characters from the socket up
-to a NUL
-.Pq Ql \e0
-byte.
-The resultant string is
-interpreted as an
-.Tn ASCII
-number, base 10.
-.It
-If the number received in step 1 is non-zero,
-it is interpreted as the port number of a secondary
-stream to be used for the
-.Em stderr .
-A second connection is then created to the specified
-port on the client's machine.
-.It
-A NUL terminated user name of at most 16 characters
-is retrieved on the initial socket.
-.It
-A NUL terminated, unencrypted password of at most
-16 characters is retrieved on the initial socket.
-.It
-A NUL terminated command to be passed to a
-shell is retrieved on the initial socket.
-The length of
-the command is limited by the upper bound on the size of
-the system's argument list.
-.It
-The
-.Nm
-utility then validates the user as is done at login time
-and, if the authentication was successful, changes
-to the user's home directory, and establishes the user
-and group protections of the user.
-If any of these steps fail the connection is
-aborted with a diagnostic message returned.
-.It
-A NUL byte is returned on the initial socket
-and the command line is passed to the normal login
-shell of the user.
-The
-shell inherits the network connections established
-by
-.Nm .
-.El
-.Sh CAVEATS
-The
-.Nm
-utility will not allow root logins unless the
-.Fl i
-option is given on the command line (typically in
-.Pa /etc/inetd.conf ) .
-It will also disallow access for users listed in
-.Pa /etc/ftpusers ,
-or users with no passwords, which were all serious security holes.
-The entire concept of rexec/rexecd is a major security hole and an example
-of how not to do things.
-The
-.Nm
-utility is disabled by default in
-.Pa /etc/inetd.conf .
-.Sh DIAGNOSTICS
-Except for the last one listed below,
-all diagnostic messages are returned on the initial socket,
-after which any network connections are closed.
-An error is indicated by a leading byte with a value of
-1 (0 is returned in step 7 above upon successful completion
-of all the steps prior to the command execution).
-.Pp
-.Bl -tag -width Ds
-.It Sy username too long
-The name is
-longer than 16 characters.
-.It Sy password too long
-The password is longer than 16 characters.
-.It Sy command too long
-The command line passed exceeds the size of the argument
-list (as configured into the system).
-.It Sy Login incorrect.
-No password file entry for the user name existed.
-.It Sy Password incorrect.
-The wrong password was supplied.
-.It Sy \&No remote directory.
-The
-.Xr chdir 1
-command to the home directory failed.
-.It Sy Try again.
-A
-.Xr fork 2
-by the server failed.
-.It Sy <shellname>: ...
-The user's login shell could not be started.
-This message is returned
-on the connection associated with the
-.Em stderr ,
-and is not preceded by a flag byte.
-.El
-.Sh SEE ALSO
-.Xr rexec 3
-.Sh HISTORY
-The
-.Nm
-utility appeared in
-.Bx 4.2 .
-.Sh BUGS
-A facility to allow all data and password exchanges to be encrypted should be
-present.
diff --git a/libexec/rexecd/rexecd.c b/libexec/rexecd/rexecd.c
deleted file mode 100644
index 54423bd..0000000
--- a/libexec/rexecd/rexecd.c
+++ /dev/null
@@ -1,326 +0,0 @@
-/*
- * Copyright (c) 1983, 1993
- *	The Regents of the University of California.  All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. 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.
- */
-
-#ifndef lint
-static const char copyright[] =
-"@(#) Copyright (c) 1983, 1993\n\
-	The Regents of the University of California.  All rights reserved.\n";
-#endif /* not lint */
-
-#ifndef lint
-#if 0
-static char sccsid[] = "@(#)rexecd.c	8.1 (Berkeley) 6/4/93";
-#endif
-static const char rcsid[] =
-  "$FreeBSD$";
-#endif /* not lint */
-
-#include <sys/param.h>
-#include <sys/ioctl.h>
-#include <sys/socket.h>
-
-#include <netinet/in.h>
-
-#include <err.h>
-#include <errno.h>
-#include <libutil.h>
-#include <paths.h>
-#include <pwd.h>
-#include <signal.h>
-#include <stdarg.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <syslog.h>
-#include <unistd.h>
-
-#include <security/pam_appl.h>
-#include <security/openpam.h>
-
-static pam_handle_t *pamh;
-static struct pam_conv pamc = {
-	openpam_nullconv,
-	NULL
-};
-static int pam_flags = PAM_SILENT|PAM_DISALLOW_NULL_AUTHTOK;
-static int pam_err;
-#define pam_ok(err) ((pam_err = (err)) == PAM_SUCCESS)
-
-char	**environ;
-char	remote[MAXHOSTNAMELEN];
-
-struct	sockaddr_storage sa;
-
-char	default_shell[] = _PATH_BSHELL;
-
-static void doit(struct sockaddr *);
-static void getstr(char *, size_t, const char *);
-static void error(const char *fmt, ...);
-
-int no_uid_0 = 1;
-
-/*
- * remote execute server:
- *	username\0
- *	password\0
- *	command\0
- *	data
- */
-/*ARGSUSED*/
-int
-main(int argc, char *argv[])
-{
-	struct sockaddr_storage from;
-	socklen_t fromlen;
-	int ch;
-
-	openlog("rexecd", LOG_PID, LOG_AUTH);
-
-	while ((ch = getopt(argc, argv, "i")) != -1)
-		switch (ch) {
-		case 'i':
-			no_uid_0 = 0;
-			break;
-		default:
-			syslog(LOG_ERR, "usage: rexecd [-i]");
-			exit(1);
-		}
-	argc -= optind;
-	argv += optind;
-
-	fromlen = sizeof (from);
-	if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0)
-		err(1, "getpeername");
-
-	realhostname_sa(remote, sizeof(remote) - 1,
-			(struct sockaddr *)&from, fromlen);
-
-	doit((struct sockaddr *)&from);
-	return(0);
-}
-
-static void
-doit(struct sockaddr *fromp)
-{
-	char *cmdbuf, *cp;
-	size_t maxcmdlen;
-	char user[16], pass[16];
-	struct passwd *pwd;
-	const void *item;
-	int fd, r, sd;
-	u_short port;
-	int pv[2], pid, cc, nfds;
-	fd_set rfds, fds;
-	char buf[BUFSIZ], sig;
-	int one = 1;
-
-	maxcmdlen = sysconf(_SC_ARG_MAX);
-	if (maxcmdlen <= 0 || (cmdbuf = malloc(maxcmdlen)) == NULL)
-		exit(1);
-
-	(void) signal(SIGINT, SIG_DFL);
-	(void) signal(SIGQUIT, SIG_DFL);
-	(void) signal(SIGTERM, SIG_DFL);
-	dup2(STDIN_FILENO, STDOUT_FILENO);
-	dup2(STDIN_FILENO, STDOUT_FILENO);
-	(void) alarm(60);
-	port = 0;
-	sd = -1;
-	for (;;) {
-		char c;
-		if (read(STDIN_FILENO, &c, 1) != 1)
-			exit(1);
-		if (c == 0)
-			break;
-		port = port * 10 + c - '0';
-	}
-	if (port != 0) {
-		sd = socket(fromp->sa_family, SOCK_STREAM, 0);
-		if (sd < 0)
-			exit(1);
-		bzero(&sa, sizeof(sa));
-		sa.ss_family = fromp->sa_family;
-		sa.ss_len = fromp->sa_len;
-		if (bind(sd, (struct sockaddr *)&sa, sa.ss_len) < 0)
-			exit(1);
-		switch (fromp->sa_family) {
-		case AF_INET:
-			((struct sockaddr_in *)(void *)fromp)->sin_port = htons(port);
-			break;
-		case AF_INET6:
-			((struct sockaddr_in6 *)(void *)fromp)->sin6_port = htons(port);
-			break;
-		default:
-			exit(1);
-		}
-		if (connect(sd, fromp, fromp->sa_len) < 0)
-			exit(1);
-	}
-	getstr(user, sizeof(user), "username");
-	getstr(pass, sizeof(pass), "password");
-	getstr(cmdbuf, maxcmdlen, "command");
-	(void) alarm(0);
-
-	if (!pam_ok(pam_start("rexecd", user, &pamc, &pamh)) ||
-	    !pam_ok(pam_set_item(pamh, PAM_RHOST, remote)) ||
-	    !pam_ok(pam_set_item(pamh, PAM_AUTHTOK, pass)) ||
-	    !pam_ok(pam_authenticate(pamh, pam_flags)) ||
-	    !pam_ok(pam_acct_mgmt(pamh, pam_flags)) ||
-	    !pam_ok(pam_get_item(pamh, PAM_USER, &item)) || item == NULL ||
-	    strlen(item) >= sizeof(user) || strcpy(user, item) == NULL ||
-	    (pwd = getpwnam(user)) == NULL ||
-	    (pwd->pw_uid == 0 && no_uid_0)) {
-		syslog(LOG_ERR, "%s LOGIN REFUSED from %s", user, remote);
-		error("Login incorrect.\n");
-		exit(1);
-	}
-
-	syslog(LOG_INFO, "login from %s as %s", remote, user);
-
-	(void) write(STDERR_FILENO, "\0", 1);
-	if (port != 0) {
-		(void) pipe(pv);
-
-		pid = fork();
-		if (pid == -1)  {
-			error("Try again.\n");
-			exit(1);
-		}
-		if (pid) {
-			/* parent */
-			(void) pam_end(pamh, pam_err);
-			(void) close(STDIN_FILENO);
-			(void) close(STDOUT_FILENO);
-			(void) close(STDERR_FILENO);
-			(void) close(pv[1]);
-			ioctl(pv[0], FIONBIO, (char *)&one);
-			/* should set sd nbio! */
-			FD_ZERO(&fds);
-			FD_SET(sd, &fds);
-			nfds = sd + 1;
-			FD_SET(pv[0], &fds);
-			if (pv[0] >= nfds)
-				nfds = pv[0] + 1;
-			do {
-				rfds = fds;
-				for (;;) {
-					r = select(nfds, &rfds, NULL, NULL, NULL);
-					if (r > 0)
-						break;
-					if (r < 0 && errno != EINTR)
-						exit(0);
-				}
-				if (FD_ISSET(sd, &rfds)) {
-					if (read(sd, &sig, 1) <= 0)
-						FD_CLR(sd, &fds);
-					else
-						killpg(pid, sig);
-				}
-				if (FD_ISSET(pv[0], &fds)) {
-					cc = read(pv[0], buf, sizeof (buf));
-					if (cc <= 0) {
-						shutdown(sd, SHUT_RDWR);
-						FD_CLR(pv[0], &fds);
-					} else {
-						(void) write(sd, buf, cc);
-					}
-				}
-			} while (FD_ISSET(sd, &fds) || FD_ISSET(pv[0], &fds));
-			exit(0);
-		}
-		/* child */
-		(void) close(sd);
-		(void) close(pv[0]);
-		dup2(pv[1], 2);
-	}
-	for (fd = getdtablesize(); fd > 2; fd--)
-		(void) close(fd);
-	if (*pwd->pw_shell == '\0')
-		pwd->pw_shell = default_shell;
-	if (setsid() == -1)
-		syslog(LOG_ERR, "setsid() failed: %m");
-	if (setlogin(pwd->pw_name) < 0)
-		syslog(LOG_ERR, "setlogin() failed: %m");
-	(void) setgid((gid_t)pwd->pw_gid);
-	initgroups(pwd->pw_name, pwd->pw_gid);
-	if (!pam_ok(pam_setcred(pamh, PAM_ESTABLISH_CRED)))
-		syslog(LOG_ERR, "pam_setcred() failed: %s",
-		    pam_strerror(pamh, pam_err));
-	(void) pam_setenv(pamh, "HOME", pwd->pw_dir, 1);
-	(void) pam_setenv(pamh, "SHELL", pwd->pw_shell, 1);
-	(void) pam_setenv(pamh, "USER", pwd->pw_name, 1);
-	(void) pam_setenv(pamh, "PATH", _PATH_DEFPATH, 1);
-	environ = pam_getenvlist(pamh);
-	(void) pam_end(pamh, pam_err);
-	(void) setuid((uid_t)pwd->pw_uid);
-	cp = strrchr(pwd->pw_shell, '/');
-	if (cp)
-		cp++;
-	else
-		cp = pwd->pw_shell;
-	if (chdir(pwd->pw_dir) < 0) {
-		error("No remote directory.\n");
-		exit(1);
-	}
-	execl(pwd->pw_shell, cp, "-c", cmdbuf, (char *)0);
-	err(1, "%s", pwd->pw_shell);
-}
-
-static void
-error(const char *fmt, ...)
-{
-	char buf[BUFSIZ];
-	va_list ap;
-
-	va_start(ap, fmt);
-	buf[0] = 1;
-	(void)vsnprintf(buf + 1, sizeof(buf) - 1, fmt, ap);
-	(void)write(STDERR_FILENO, buf, strlen(buf));
-	va_end(ap);
-}
-
-static void
-getstr(char *buf, size_t cnt, const char *field)
-{
-	char c;
-
-	do {
-		if (read(STDIN_FILENO, &c, 1) != 1)
-			exit(1);
-		*buf++ = c;
-		if (--cnt == 0) {
-			error("%s too long\n", field);
-			exit(1);
-		}
-	} while (c != 0);
-}