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rexecd.c revision 1.11 
      1 /*	$NetBSD: rexecd.c,v 1.11 2002/06/05 23:05:34 itojun Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1983, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #ifndef lint
     38 __COPYRIGHT("@(#) Copyright (c) 1983, 1993\n\
     39 	The Regents of the University of California.  All rights reserved.\n");
     40 #if 0
     41 static char sccsid[] = "from: @(#)rexecd.c	8.1 (Berkeley) 6/4/93";
     42 #else
     43 __RCSID("$NetBSD: rexecd.c,v 1.11 2002/06/05 23:05:34 itojun Exp $");
     44 #endif
     45 #endif /* not lint */
     46 
     47 #include <sys/param.h>
     48 #include <sys/ioctl.h>
     49 #include <sys/poll.h>
     50 #include <sys/socket.h>
     51 #include <sys/syslog.h>
     52 #include <sys/time.h>
     53 
     54 #include <netinet/in.h>
     55 
     56 #include <err.h>
     57 #include <errno.h>
     58 #include <netdb.h>
     59 #include <paths.h>
     60 #include <pwd.h>
     61 #include <signal.h>
     62 #include <stdarg.h>
     63 #include <stdio.h>
     64 #include <stdlib.h>
     65 #include <string.h>
     66 #include <unistd.h>
     67 
     68 void error __P((const char *, ...))
     69      __attribute__((__format__(__printf__, 1, 2)));
     70 int main __P((int, char **));
     71 void doit __P((int, struct sockaddr *));
     72 void getstr __P((char *, int, char *));
     73 
     74 char	username[32 + 1] = "USER=";
     75 char	homedir[PATH_MAX + 1] = "HOME=";
     76 char	shell[PATH_MAX + 1] = "SHELL=";
     77 char	path[sizeof(_PATH_DEFPATH) + sizeof("PATH=")] = "PATH=";
     78 char	*envinit[] = { homedir, shell, path, username, 0 };
     79 char	**environ;
     80 int	log;
     81 
     82 /*
     83  * remote execute server:
     84  *	username\0
     85  *	password\0
     86  *	command\0
     87  *	data
     88  */
     89 int
     90 main(argc, argv)
     91 	int argc;
     92 	char **argv;
     93 {
     94 	struct sockaddr_storage from;
     95 	int fromlen, ch;
     96 
     97 	while ((ch = getopt(argc, argv, "l")) != -1)
     98 		switch (ch) {
     99 		case 'l':
    100 			log = 1;
    101 			openlog("rexecd", LOG_PID, LOG_DAEMON);
    102 			break;
    103 		default:
    104 			exit(1);
    105 		}
    106 
    107 	fromlen = sizeof (from);
    108 	if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0)
    109 		err(1, "getpeername");
    110 
    111 	doit(0, (struct sockaddr *)&from);
    112 	exit(0);
    113 }
    114 
    115 void
    116 doit(f, fromp)
    117 	int f;
    118 	struct sockaddr *fromp;
    119 {
    120 	struct pollfd fds[2];
    121 	char cmdbuf[NCARGS+1], *namep;
    122 	const char *cp;
    123 	char user[16], pass[16];
    124 	char buf[BUFSIZ], sig;
    125 	struct passwd *pwd;
    126 	int s = -1; /* XXX gcc */
    127 	int pv[2], pid, cc;
    128 	int one = 1;
    129 	in_port_t port;
    130 
    131 	(void)signal(SIGINT, SIG_DFL);
    132 	(void)signal(SIGQUIT, SIG_DFL);
    133 	(void)signal(SIGTERM, SIG_DFL);
    134 	dup2(f, 0);
    135 	dup2(f, 1);
    136 	dup2(f, 2);
    137 	(void)alarm(60);
    138 	port = 0;
    139 	for (;;) {
    140 		char c;
    141 		if (read(f, &c, 1) != 1) {
    142 			if (log)
    143 				syslog(LOG_ERR,
    144 				    "initial read failed");
    145 			exit(1);
    146 		}
    147 		if (c == 0)
    148 			break;
    149 		port = port * 10 + c - '0';
    150 	}
    151 	(void)alarm(0);
    152 	if (port != 0) {
    153 		s = socket(fromp->sa_family, SOCK_STREAM, 0);
    154 		if (s < 0) {
    155 			if (log)
    156 				syslog(LOG_ERR, "socket: %m");
    157 			exit(1);
    158 		}
    159 		(void)alarm(60);
    160 		switch (fromp->sa_family) {
    161 		case AF_INET:
    162 			((struct sockaddr_in *)fromp)->sin_port = htons(port);
    163 			break;
    164 		case AF_INET6:
    165 			((struct sockaddr_in6 *)fromp)->sin6_port = htons(port);
    166 			break;
    167 		default:
    168 			syslog(LOG_ERR, "unsupported address family");
    169 			exit(1);
    170 		}
    171 		if (connect(s, (struct sockaddr *)fromp, fromp->sa_len) < 0) {
    172 			if (log)
    173 				syslog(LOG_ERR, "connect: %m");
    174 			exit(1);
    175 		}
    176 		(void)alarm(0);
    177 	}
    178 	getstr(user, sizeof(user), "username");
    179 	getstr(pass, sizeof(pass), "password");
    180 	getstr(cmdbuf, sizeof(cmdbuf), "command");
    181 	setpwent();
    182 	pwd = getpwnam(user);
    183 	if (pwd == NULL) {
    184 		error("Login incorrect.\n");
    185 		if (log)
    186 			syslog(LOG_ERR, "no such user %s", user);
    187 		exit(1);
    188 	}
    189 	endpwent();
    190 	if (*pwd->pw_passwd != '\0') {
    191 		namep = crypt(pass, pwd->pw_passwd);
    192 		if (strcmp(namep, pwd->pw_passwd)) {
    193 			error("Password incorrect.\n");	/* XXX: wrong! */
    194 			if (log)
    195 				syslog(LOG_ERR, "incorrect password for %s",
    196 				    user);
    197 			exit(1);
    198 		}
    199 	} else
    200 		(void)crypt("dummy password", "PA");	/* must always crypt */
    201 	if (chdir(pwd->pw_dir) < 0) {
    202 		error("No remote directory.\n");
    203 		if (log)
    204 			syslog(LOG_ERR, "%s does not exist for %s", pwd->pw_dir,
    205 			    user);
    206 		exit(1);
    207 	}
    208 	(void)write(2, "\0", 1);
    209 	if (port) {
    210 		if (pipe(pv) < 0 || (pid = fork()) == -1) {
    211 			error("Try again.\n");
    212 			if (log)
    213 				syslog(LOG_ERR,"pipe or fork failed for %s: %m",
    214 				    user);
    215 			exit(1);
    216 		}
    217 		if (pid) {
    218 			(void)close(0);
    219 			(void)close(1);
    220 			(void)close(2);
    221 			(void)close(f);
    222 			(void)close(pv[1]);
    223 			fds[0].fd = s;
    224 			fds[1].fd = pv[0];
    225 			fds[0].events = fds[1].events = POLLIN;
    226 			if (ioctl(pv[1], FIONBIO, (char *)&one) < 0)
    227 				_exit(1);
    228 			/* should set s nbio! */
    229 			do {
    230 				if (poll(fds, 2, 0) < 0) {
    231 					close(s);
    232 					close(pv[0]);
    233 					_exit(1);
    234 				}
    235 				if (fds[0].revents & POLLIN) {
    236 					if (read(s, &sig, 1) <= 0)
    237 						fds[0].events = 0;
    238 					else
    239 						killpg(pid, sig);
    240 				}
    241 				if (fds[1].revents & POLLIN) {
    242 					cc = read(pv[0], buf, sizeof (buf));
    243 					if (cc <= 0) {
    244 						shutdown(s, 1+1);
    245 						fds[1].events = 0;
    246 					} else
    247 						(void)write(s, buf, cc);
    248 				}
    249 			} while ((fds[0].events | fds[1].events) & POLLIN);
    250 			_exit(0);
    251 		}
    252 		(void)setpgrp(0, getpid());
    253 		(void)close(s);
    254 		(void)close(pv[0]);
    255 		if (dup2(pv[1], 2) < 0) {
    256 			error("Try again.\n");
    257 			if (log)
    258 				syslog(LOG_ERR, "dup2 failed for %s", user);
    259 			exit(1);
    260 		}
    261 	}
    262 	if (*pwd->pw_shell == '\0')
    263 		pwd->pw_shell = _PATH_BSHELL;
    264 	if (f > 2)
    265 		(void)close(f);
    266 	if (setlogin(pwd->pw_name) < 0 ||
    267 	    initgroups(pwd->pw_name, pwd->pw_gid) < 0 ||
    268 	    setgid((gid_t)pwd->pw_gid) < 0 ||
    269 	    setuid((uid_t)pwd->pw_uid) < 0) {
    270 		error("Try again.\n");
    271 		if (log)
    272 			syslog(LOG_ERR, "could not set permissions for %s: %m",
    273 			    user);
    274 		exit(1);
    275 	}
    276 	(void)strcat(path, _PATH_DEFPATH);
    277 	environ = envinit;
    278 	strncat(homedir, pwd->pw_dir, sizeof(homedir) - 6);
    279 	strncat(shell, pwd->pw_shell, sizeof(shell) - 7);
    280 	strncat(username, pwd->pw_name, sizeof(username) - 6);
    281 	cp = strrchr(pwd->pw_shell, '/');
    282 	if (cp)
    283 		cp++;
    284 	else
    285 		cp = pwd->pw_shell;
    286 	if (log)
    287 		syslog(LOG_INFO, "running command for %s: %s", user, cmdbuf);
    288 	execl(pwd->pw_shell, cp, "-c", cmdbuf, 0);
    289 	perror(pwd->pw_shell);
    290 	if (log)
    291 		syslog(LOG_ERR, "execl failed for %s: %m", user);
    292 	exit(1);
    293 }
    294 
    295 void
    296 error(const char *fmt, ...)
    297 {
    298 	char buf[BUFSIZ];
    299 	va_list ap;
    300 
    301 	va_start(ap, fmt);
    302 	buf[0] = 1;
    303 	(void)vsnprintf(buf+1, sizeof(buf) - 1, fmt, ap);
    304 	(void)write(2, buf, strlen(buf));
    305 	va_end(ap);
    306 }
    307 
    308 void
    309 getstr(buf, cnt, err)
    310 	char *buf;
    311 	int cnt;
    312 	char *err;
    313 {
    314 	char c;
    315 
    316 	do {
    317 		if (read(0, &c, 1) != 1)
    318 			exit(1);
    319 		*buf++ = c;
    320 		if (--cnt == 0) {
    321 			error("%s too long\n", err);
    322 			exit(1);
    323 		}
    324 	} while (c != 0);
    325 }
    326