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/*      $OpenBSD: rcmdsh.c,v 1.5 1998/04/25 16:23:58 millert Exp $      */

/*

 * Copyright (c) 2001, MagniComp

 * 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. Neither the name of the MagniComp 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 COPYRIGHT HOLDERS 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.

 */

/*

 * This is an rcmd() replacement originally by

 * Chris Siebenmann <cks@utcc.utoronto.ca>.

 */

#include <sys/cdefs.h>

#include <sys/types.h>

#include <machine/endian.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <sys/wait.h>

#include <errno.h>

#include <netdb.h>

#include <paths.h>

#include <pwd.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>

#ifndef _PATH_RSH

#define _PATH_RSH       "/usr/bin/rsh"

#endif

/*

 * This is a replacement rcmd() function that uses the rsh(1)

 * program in place of a direct rcmd(3) function call so as to

 * avoid having to be root.  Note that rport is ignored.

 */

int

rcmdsh(ahost, rport, locuser, remuser, cmd, rshprog)

        char **ahost;

        int rport;

        const char *locuser, *remuser, *cmd, *rshprog;

{

        struct addrinfo hints, *res;

        int cpid, sp[2], error;

        char *p;

        struct passwd *pw;

        char num[8];

        static char hbuf[NI_MAXHOST];

        /* What rsh/shell to use. */

        if (rshprog == NULL)

                rshprog = _PATH_RSH;

        /* locuser must exist on this host. */

        if ((pw = getpwnam(locuser)) == NULL) {

                (void)fprintf(stderr, "rcmdsh: unknown user: %s\n", locuser);

                return (-1);

        }

        /* Validate remote hostname. */

        if (strcmp(*ahost, "localhost") != 0) {

                memset(&hints, 0, sizeof(hints));

                hints.ai_flags = AI_CANONNAME;

                hints.ai_family = PF_UNSPEC;

                hints.ai_socktype = SOCK_STREAM;

                (void)snprintf(num, sizeof(num), "%d", ntohs(rport));

                error = getaddrinfo(*ahost, num, &hints, &res);

                if (error) {

                        fprintf(stderr, "rcmdsh: getaddrinfo: %s\n",

                                gai_strerror(error));

                        return (-1);

                }

                if (res->ai_canonname) {

                        strncpy(hbuf, res->ai_canonname, sizeof(hbuf) - 1);

                        hbuf[sizeof(hbuf) - 1] = '\0';

                        *ahost = hbuf;

                }

                freeaddrinfo(res);

        }

        /* Get a socketpair we'll use for stdin and stdout. */

        if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, sp) == -1) {

                perror("rcmdsh: socketpair");

                return (-1);

        }

        cpid = fork();

        if (cpid == -1) {

                perror("rcmdsh: fork failed");

                return (-1);

        } else if (cpid == 0) {

                /*

                 * Child.  We use sp[1] to be stdin/stdout, and close sp[0].

                 */

                (void)close(sp[0]);

                if (dup2(sp[1], 0) == -1 || dup2(0, 1) == -1) {

                        perror("rcmdsh: dup2 failed");

                        _exit(255);

                }

                /* Fork again to lose parent. */

                cpid = fork();

                if (cpid == -1) {

                        perror("rcmdsh: fork to lose parent failed");

                        _exit(255);

                }

                if (cpid > 0)

                        _exit(0);

                /* In grandchild here.  Become local user for rshprog. */

                if (setuid(pw->pw_uid) == -1) {

                        (void)fprintf(stderr, "rcmdsh: setuid(%u): %s\n",

                            pw->pw_uid, strerror(errno));

                        _exit(255);

                }

                /*

                 * If remote host is "localhost" and local and remote users

                 * are the same, avoid running remote shell for efficiency.

                 */

                if (strcmp(*ahost, "localhost") == 0 &&

                    strcmp(locuser, remuser) == 0) {

                        if (pw->pw_shell[0] == '\0')

                                rshprog = _PATH_BSHELL;

                        else

                                rshprog = pw->pw_shell;

                        p = strrchr(rshprog, '/');

                        execlp(rshprog, p ? p + 1 : rshprog, "-c", cmd,

                            (char *)NULL);

                } else {

                        p = strrchr(rshprog, '/');

                        execlp(rshprog, p ? p + 1 : rshprog, *ahost, "-l",

                            remuser, cmd, (char *)NULL);

                }

                (void)fprintf(stderr, "rcmdsh: execlp %s failed: %s\n",

                    rshprog, strerror(errno));

                _exit(255);

        } else {

                /* Parent. close sp[1], return sp[0]. */

                (void)close(sp[1]);

                /* Reap child. */

                (void)wait(NULL);

                return (sp[0]);

        }

        /* NOTREACHED */

}