xref: /freebsd/lib/libc/net/rcmdsh.c (revision 8823d24b48f0d4b683a41c4ca00db2fd7044c725)
1*8823d24bSXin LI /*	$OpenBSD: rcmdsh.c,v 1.7 2002/03/12 00:05:44 millert Exp $	*/
2d4567212SWarner Losh 
3d4567212SWarner Losh /*
49368e99fSJacques Vidrine  * Copyright (c) 2001, MagniComp
59368e99fSJacques Vidrine  * All rights reserved.
69368e99fSJacques Vidrine  *
79368e99fSJacques Vidrine  * Redistribution and use in source and binary forms, with or without
89368e99fSJacques Vidrine  * modification, are permitted provided that the following conditions
99368e99fSJacques Vidrine  * are met:
109368e99fSJacques Vidrine  * 1. Redistributions of source code must retain the above copyright
119368e99fSJacques Vidrine  *    notice, this list of conditions and the following disclaimer.
129368e99fSJacques Vidrine  * 2. Redistributions in binary form must reproduce the above copyright
139368e99fSJacques Vidrine  *    notice, this list of conditions and the following disclaimer in
149368e99fSJacques Vidrine  *    the documentation and/or other materials provided with the distribution.
159368e99fSJacques Vidrine  * 3. Neither the name of the MagniComp nor the names of its contributors may
169368e99fSJacques Vidrine  *    be used to endorse or promote products derived from this software
179368e99fSJacques Vidrine  *    without specific prior written permission.
189368e99fSJacques Vidrine  *
199368e99fSJacques Vidrine  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
209368e99fSJacques Vidrine  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
219368e99fSJacques Vidrine  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
229368e99fSJacques Vidrine  * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
239368e99fSJacques Vidrine  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
249368e99fSJacques Vidrine  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
259368e99fSJacques Vidrine  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
269368e99fSJacques Vidrine  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
279368e99fSJacques Vidrine  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
289368e99fSJacques Vidrine  * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
299368e99fSJacques Vidrine  */
309368e99fSJacques Vidrine 
319368e99fSJacques Vidrine /*
32d4567212SWarner Losh  * This is an rcmd() replacement originally by
33d4567212SWarner Losh  * Chris Siebenmann <cks@utcc.utoronto.ca>.
34d4567212SWarner Losh  */
35d4567212SWarner Losh 
36e117e7a5SRuslan Ermilov #include <sys/cdefs.h>
37e117e7a5SRuslan Ermilov __FBSDID("$FreeBSD$");
38d4567212SWarner Losh 
39d4567212SWarner Losh #include <sys/types.h>
40d4567212SWarner Losh #include <sys/socket.h>
41d4567212SWarner Losh #include <sys/wait.h>
422bbd7cf8SJacques Vidrine #include <arpa/inet.h>
43e117e7a5SRuslan Ermilov 
44d4567212SWarner Losh #include <errno.h>
45d4567212SWarner Losh #include <netdb.h>
46e117e7a5SRuslan Ermilov #include <paths.h>
47e117e7a5SRuslan Ermilov #include <pwd.h>
48d4567212SWarner Losh #include <stdio.h>
49d4567212SWarner Losh #include <string.h>
50d4567212SWarner Losh #include <unistd.h>
51d4567212SWarner Losh 
52d4567212SWarner Losh /*
53d4567212SWarner Losh  * This is a replacement rcmd() function that uses the rsh(1)
54d4567212SWarner Losh  * program in place of a direct rcmd(3) function call so as to
55d4567212SWarner Losh  * avoid having to be root.  Note that rport is ignored.
56d4567212SWarner Losh  */
57d4567212SWarner Losh int
58*8823d24bSXin LI rcmdsh(char **ahost, int rport, const char *locuser, const char *remuser,
59*8823d24bSXin LI     const char *cmd, const char *rshprog)
60d4567212SWarner Losh {
617b0e82a9SHajimu UMEMOTO 	struct addrinfo hints, *res;
62*8823d24bSXin LI 	int sp[2], error;
63*8823d24bSXin LI 	pid_t cpid;
64d4567212SWarner Losh 	char *p;
65d4567212SWarner Losh 	struct passwd *pw;
667b0e82a9SHajimu UMEMOTO 	char num[8];
677b0e82a9SHajimu UMEMOTO 	static char hbuf[NI_MAXHOST];
68d4567212SWarner Losh 
69d4567212SWarner Losh 	/* What rsh/shell to use. */
70d4567212SWarner Losh 	if (rshprog == NULL)
71d4567212SWarner Losh 		rshprog = _PATH_RSH;
72d4567212SWarner Losh 
73d4567212SWarner Losh 	/* locuser must exist on this host. */
74d4567212SWarner Losh 	if ((pw = getpwnam(locuser)) == NULL) {
75d4567212SWarner Losh 		(void)fprintf(stderr, "rcmdsh: unknown user: %s\n", locuser);
76d4567212SWarner Losh 		return (-1);
77d4567212SWarner Losh 	}
78d4567212SWarner Losh 
79d4567212SWarner Losh 	/* Validate remote hostname. */
80d4567212SWarner Losh 	if (strcmp(*ahost, "localhost") != 0) {
817b0e82a9SHajimu UMEMOTO 		memset(&hints, 0, sizeof(hints));
827b0e82a9SHajimu UMEMOTO 		hints.ai_flags = AI_CANONNAME;
837b0e82a9SHajimu UMEMOTO 		hints.ai_family = PF_UNSPEC;
847b0e82a9SHajimu UMEMOTO 		hints.ai_socktype = SOCK_STREAM;
852bbd7cf8SJacques Vidrine 		(void)snprintf(num, sizeof(num), "%u",
862bbd7cf8SJacques Vidrine 		    (unsigned int)ntohs(rport));
877b0e82a9SHajimu UMEMOTO 		error = getaddrinfo(*ahost, num, &hints, &res);
887b0e82a9SHajimu UMEMOTO 		if (error) {
897b0e82a9SHajimu UMEMOTO 			fprintf(stderr, "rcmdsh: getaddrinfo: %s\n",
907b0e82a9SHajimu UMEMOTO 				gai_strerror(error));
91d4567212SWarner Losh 			return (-1);
92d4567212SWarner Losh 		}
937b0e82a9SHajimu UMEMOTO 		if (res->ai_canonname) {
947b0e82a9SHajimu UMEMOTO 			strncpy(hbuf, res->ai_canonname, sizeof(hbuf) - 1);
957b0e82a9SHajimu UMEMOTO 			hbuf[sizeof(hbuf) - 1] = '\0';
967b0e82a9SHajimu UMEMOTO 			*ahost = hbuf;
977b0e82a9SHajimu UMEMOTO 		}
987b0e82a9SHajimu UMEMOTO 		freeaddrinfo(res);
99d4567212SWarner Losh 	}
100d4567212SWarner Losh 
101d4567212SWarner Losh 	/* Get a socketpair we'll use for stdin and stdout. */
102e117e7a5SRuslan Ermilov 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, sp) == -1) {
103d4567212SWarner Losh 		perror("rcmdsh: socketpair");
104d4567212SWarner Losh 		return (-1);
105d4567212SWarner Losh 	}
106d4567212SWarner Losh 
107d4567212SWarner Losh 	cpid = fork();
108e117e7a5SRuslan Ermilov 	if (cpid == -1) {
109d4567212SWarner Losh 		perror("rcmdsh: fork failed");
110d4567212SWarner Losh 		return (-1);
111d4567212SWarner Losh 	} else if (cpid == 0) {
112d4567212SWarner Losh 		/*
113d4567212SWarner Losh 		 * Child.  We use sp[1] to be stdin/stdout, and close sp[0].
114d4567212SWarner Losh 		 */
115d4567212SWarner Losh 		(void)close(sp[0]);
116e117e7a5SRuslan Ermilov 		if (dup2(sp[1], 0) == -1 || dup2(0, 1) == -1) {
117d4567212SWarner Losh 			perror("rcmdsh: dup2 failed");
118d4567212SWarner Losh 			_exit(255);
119d4567212SWarner Losh 		}
120d4567212SWarner Losh 		/* Fork again to lose parent. */
121d4567212SWarner Losh 		cpid = fork();
122e117e7a5SRuslan Ermilov 		if (cpid == -1) {
123d4567212SWarner Losh 			perror("rcmdsh: fork to lose parent failed");
124d4567212SWarner Losh 			_exit(255);
125d4567212SWarner Losh 		}
126d4567212SWarner Losh 		if (cpid > 0)
127d4567212SWarner Losh 			_exit(0);
128d4567212SWarner Losh 
129d4567212SWarner Losh 		/* In grandchild here.  Become local user for rshprog. */
130e117e7a5SRuslan Ermilov 		if (setuid(pw->pw_uid) == -1) {
131d4567212SWarner Losh 			(void)fprintf(stderr, "rcmdsh: setuid(%u): %s\n",
132d4567212SWarner Losh 			    pw->pw_uid, strerror(errno));
133d4567212SWarner Losh 			_exit(255);
134d4567212SWarner Losh 		}
135d4567212SWarner Losh 
136d4567212SWarner Losh 		/*
137e117e7a5SRuslan Ermilov 		 * If remote host is "localhost" and local and remote users
138d4567212SWarner Losh 		 * are the same, avoid running remote shell for efficiency.
139d4567212SWarner Losh 		 */
140e117e7a5SRuslan Ermilov 		if (strcmp(*ahost, "localhost") == 0 &&
141e117e7a5SRuslan Ermilov 		    strcmp(locuser, remuser) == 0) {
142d4567212SWarner Losh 			if (pw->pw_shell[0] == '\0')
143d4567212SWarner Losh 				rshprog = _PATH_BSHELL;
144d4567212SWarner Losh 			else
145d4567212SWarner Losh 				rshprog = pw->pw_shell;
146d4567212SWarner Losh 			p = strrchr(rshprog, '/');
147d4567212SWarner Losh 			execlp(rshprog, p ? p + 1 : rshprog, "-c", cmd,
148d4567212SWarner Losh 			    (char *)NULL);
149d4567212SWarner Losh 		} else {
150d4567212SWarner Losh 			p = strrchr(rshprog, '/');
151d4567212SWarner Losh 			execlp(rshprog, p ? p + 1 : rshprog, *ahost, "-l",
152d4567212SWarner Losh 			    remuser, cmd, (char *)NULL);
153d4567212SWarner Losh 		}
154d4567212SWarner Losh 		(void)fprintf(stderr, "rcmdsh: execlp %s failed: %s\n",
155d4567212SWarner Losh 		    rshprog, strerror(errno));
156d4567212SWarner Losh 		_exit(255);
157d4567212SWarner Losh 	} else {
158d4567212SWarner Losh 		/* Parent. close sp[1], return sp[0]. */
159d4567212SWarner Losh 		(void)close(sp[1]);
160d4567212SWarner Losh 		/* Reap child. */
161d4567212SWarner Losh 		(void)wait(NULL);
162d4567212SWarner Losh 		return (sp[0]);
163d4567212SWarner Losh 	}
164d4567212SWarner Losh 	/* NOTREACHED */
165d4567212SWarner Losh }
166