rexecd/rexecd.c

/*
 * Copyright (c) 1983 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1983 The Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)rexecd.c    5.7 (Berkeley) 1/4/89";
#endif /* not lint */

#include <sys/ioctl.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>

#include <netinet/in.h>

#include <stdio.h>
#include <errno.h>
#include <pwd.h>
#include <signal.h>
#include <netdb.h>

extern  errno;
struct  passwd *getpwnam();
char    *crypt(), *rindex(), *strncat();
/*VARARGS1*/
int     error();

/*
 * remote execute server:
 *      username\0
 *      password\0
 *      command\0
 *      data
 */
/*ARGSUSED*/
main(argc, argv)
        int argc;
        char **argv;
{
        struct sockaddr_in from;
        int fromlen;

        fromlen = sizeof (from);
        if (getpeername(0, &from, &fromlen) < 0) {
                fprintf(stderr, "%s: ", argv[0]);
                perror("getpeername");
                exit(1);
        }
        doit(0, &from);
}

char    username[20] = "USER=";
char    homedir[64] = "HOME=";
char    shell[64] = "SHELL=";
char    *envinit[] =
            {homedir, shell, "PATH=:/usr/ucb:/bin:/usr/bin", username, 0};
char    **environ;

struct  sockaddr_in asin = { AF_INET };

doit(f, fromp)
        int f;
        struct sockaddr_in *fromp;
{
        char cmdbuf[NCARGS+1], *cp, *namep;
        char user[16], pass[16];
        struct passwd *pwd;
        int s;
        u_short port;
        int pv[2], pid, ready, readfrom, cc;
        char buf[BUFSIZ], sig;
        int one = 1;

        (void) signal(SIGINT, SIG_DFL);
        (void) signal(SIGQUIT, SIG_DFL);
        (void) signal(SIGTERM, SIG_DFL);
#ifdef DEBUG
        { int t = open("/dev/tty", 2);
          if (t >= 0) {
                ioctl(t, TIOCNOTTY, (char *)0);
                (void) close(t);
          }
        }
#endif
        dup2(f, 0);
        dup2(f, 1);
        dup2(f, 2);
        (void) alarm(60);
        port = 0;
        for (;;) {
                char c;
                if (read(f, &c, 1) != 1)
                        exit(1);
                if (c == 0)
                        break;
                port = port * 10 + c - '0';
        }
        (void) alarm(0);
        if (port != 0) {
                s = socket(AF_INET, SOCK_STREAM, 0);
                if (s < 0)
                        exit(1);
                if (bind(s, &asin, sizeof (asin)) < 0)
                        exit(1);
                (void) alarm(60);
                fromp->sin_port = htons(port);
                if (connect(s, fromp, sizeof (*fromp)) < 0)
                        exit(1);
                (void) alarm(0);
        }
        getstr(user, sizeof(user), "username");
        getstr(pass, sizeof(pass), "password");
        getstr(cmdbuf, sizeof(cmdbuf), "command");
        setpwent();
        pwd = getpwnam(user);
        if (pwd == NULL) {
                error("Login incorrect.\n");
                exit(1);
        }
        endpwent();
        if (*pwd->pw_passwd != '\0') {
                namep = crypt(pass, pwd->pw_passwd);
                if (strcmp(namep, pwd->pw_passwd)) {
                        error("Password incorrect.\n");
                        exit(1);
                }
        }
        if (chdir(pwd->pw_dir) < 0) {
                error("No remote directory.\n");
                exit(1);
        }
        (void) write(2, "\0", 1);
        if (port) {
                (void) pipe(pv);
                pid = fork();
                if (pid == -1)  {
                        error("Try again.\n");
                        exit(1);
                }
                if (pid) {
                        (void) close(0); (void) close(1); (void) close(2);
                        (void) close(f); (void) close(pv[1]);
                        readfrom = (1<<s) | (1<<pv[0]);
                        ioctl(pv[1], FIONBIO, (char *)&one);
                        /* should set s nbio! */
                        do {
                                ready = readfrom;
                                (void) select(16, &ready, (fd_set *)0,
                                    (fd_set *)0, (struct timeval *)0);
                                if (ready & (1<<s)) {
                                        if (read(s, &sig, 1) <= 0)
                                                readfrom &= ~(1<<s);
                                        else
                                                killpg(pid, sig);
                                }
                                if (ready & (1<<pv[0])) {
                                        cc = read(pv[0], buf, sizeof (buf));
                                        if (cc <= 0) {
                                                shutdown(s, 1+1);
                                                readfrom &= ~(1<<pv[0]);
                                        } else
                                                (void) write(s, buf, cc);
                                }
                        } while (readfrom);
                        exit(0);
                }
                setpgrp(0, getpid());
                (void) close(s); (void)close(pv[0]);
                dup2(pv[1], 2);
        }
        if (*pwd->pw_shell == '\0')
                pwd->pw_shell = "/bin/sh";
        if (f > 2)
                (void) close(f);
        (void) setgid((gid_t)pwd->pw_gid);
        initgroups(pwd->pw_name, pwd->pw_gid);
        (void) setuid((uid_t)pwd->pw_uid);
        environ = envinit;
        strncat(homedir, pwd->pw_dir, sizeof(homedir)-6);
        strncat(shell, pwd->pw_shell, sizeof(shell)-7);
        strncat(username, pwd->pw_name, sizeof(username)-6);
        cp = rindex(pwd->pw_shell, '/');
        if (cp)
                cp++;
        else
                cp = pwd->pw_shell;
        execl(pwd->pw_shell, cp, "-c", cmdbuf, 0);
        perror(pwd->pw_shell);
        exit(1);
}

/*VARARGS1*/
error(fmt, a1, a2, a3)
        char *fmt;
        int a1, a2, a3;
{
        char buf[BUFSIZ];

        buf[0] = 1;
        (void) sprintf(buf+1, fmt, a1, a2, a3);
        (void) write(2, buf, strlen(buf));
}

getstr(buf, cnt, err)
        char *buf;
        int cnt;
        char *err;
{
        char c;

        do {
                if (read(0, &c, 1) != 1)
                        exit(1);
                *buf++ = c;
                if (--cnt == 0) {
                        error("%s too long\n", err);
                        exit(1);
                }
        } while (c != 0);
}