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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>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <arpa/inet.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), "%u",
(unsigned int)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 */
}
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