a13e275f66
it is both uneeded and breaks certain lock-step timing in the rexec protocol. Yes, an attacker can "relay" connections using this trick, but a properly configured firewall that would make this sort of subterfuge necessary in the first place (instead of direct packet spoofing) would also thwart useful attacks based on this.
313 lines
7.6 KiB
C
313 lines
7.6 KiB
C
/*
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* Copyright (c) 1983, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: rexecd.c,v 1.8 1996/09/22 21:54:45 wosch Exp $
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*/
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#ifndef lint
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static char copyright[] =
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"@(#) Copyright (c) 1983, 1993\n\
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The Regents of the University of California. All rights reserved.\n";
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#endif /* not lint */
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#ifndef lint
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static char sccsid[] = "@(#)rexecd.c 8.1 (Berkeley) 6/4/93";
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#endif /* not lint */
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#include <sys/param.h>
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#include <sys/ioctl.h>
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#include <sys/socket.h>
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#include <sys/time.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <errno.h>
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#include <netdb.h>
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#include <paths.h>
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#include <pwd.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <syslog.h>
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#include <netdb.h>
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/*VARARGS1*/
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int error();
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char username[20] = "USER=";
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char homedir[64] = "HOME=";
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char shell[64] = "SHELL=";
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char path[sizeof(_PATH_DEFPATH) + sizeof("PATH=")] = "PATH=";
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char *envinit[] =
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{homedir, shell, path, username, 0};
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char **environ;
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char *remote;
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struct sockaddr_in asin = { AF_INET };
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/*
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* remote execute server:
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* username\0
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* password\0
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* command\0
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* data
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*/
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/*ARGSUSED*/
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main(argc, argv)
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int argc;
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char **argv;
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{
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struct sockaddr_in from;
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int fromlen;
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struct hostent *hp;
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openlog(argv[0], LOG_PID, LOG_AUTH);
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fromlen = sizeof (from);
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if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
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(void)fprintf(stderr,
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"rexecd: getpeername: %s\n", strerror(errno));
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exit(1);
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}
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hp = gethostbyaddr((char *) &from.sin_addr, sizeof(from.sin_addr),
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from.sin_family);
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remote = inet_ntoa(from.sin_addr);
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remote = (hp != NULL) ? hp->h_name : inet_ntoa(from.sin_addr);
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doit(0, &from);
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}
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doit(f, fromp)
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int f;
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struct sockaddr_in *fromp;
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{
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FILE *fp;
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char cmdbuf[NCARGS+1], *cp, *namep;
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#ifdef SKEY
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char *skey_crypt();
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char user[16], pass[100];
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#else /* SKEY */
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char user[16], pass[16];
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#endif /* SKEY */
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struct passwd *pwd;
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int s;
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u_short port;
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int pv[2], pid, ready, readfrom, cc;
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char buf[BUFSIZ], sig;
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int one = 1;
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(void) signal(SIGINT, SIG_DFL);
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(void) signal(SIGQUIT, SIG_DFL);
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(void) signal(SIGTERM, SIG_DFL);
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#ifdef DEBUG
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{ int t = open(_PATH_TTY, 2);
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if (t >= 0) {
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ioctl(t, TIOCNOTTY, (char *)0);
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(void) close(t);
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}
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}
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#endif
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dup2(f, 0);
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dup2(f, 1);
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dup2(f, 2);
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(void) alarm(60);
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port = 0;
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for (;;) {
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char c;
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if (read(f, &c, 1) != 1)
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exit(1);
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if (c == 0)
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break;
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port = port * 10 + c - '0';
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}
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(void) alarm(0);
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if (port != 0) {
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s = socket(AF_INET, SOCK_STREAM, 0);
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if (s < 0)
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exit(1);
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if (bind(s, (struct sockaddr *)&asin, sizeof (asin)) < 0)
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exit(1);
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(void) alarm(60);
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fromp->sin_port = htons(port);
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if (connect(s, (struct sockaddr *)fromp, sizeof (*fromp)) < 0)
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exit(1);
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(void) alarm(0);
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}
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getstr(user, sizeof(user), "username");
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getstr(pass, sizeof(pass), "password");
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getstr(cmdbuf, sizeof(cmdbuf), "command");
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setpwent();
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pwd = getpwnam(user);
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if (pwd == NULL) {
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error("Login incorrect.\n");
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exit(1);
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}
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endpwent();
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if (*pwd->pw_passwd != '\0') {
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#ifdef SKEY
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namep = skey_crypt(pass, pwd->pw_passwd, pwd,
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skeyaccess(user, NULL, remote));
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#else /* SKEY */
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namep = crypt(pass, pwd->pw_passwd);
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#endif /* SKEY */
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if (strcmp(namep, pwd->pw_passwd)) {
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syslog(LOG_ERR, "LOGIN FAILURE from %s, %s",
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remote, user);
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error("Login incorrect.\n");
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exit(1);
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}
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}
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if (pwd->pw_uid == 0 || *pwd->pw_passwd == '\0' ||
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(pwd->pw_expire && time(NULL) >= pwd->pw_expire)) {
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syslog(LOG_ERR, "%s LOGIN REFUSED from %s", user, remote);
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error("Login incorrect.\n");
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exit(1);
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}
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if ((fp = fopen(_PATH_FTPUSERS, "r")) != NULL) {
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while (fgets(buf, sizeof(buf), fp) != NULL) {
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if ((cp = index(buf, '\n')) != NULL)
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*cp = '\0';
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if (strcmp(buf, pwd->pw_name) == 0) {
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syslog(LOG_ERR, "%s LOGIN REFUSED from %s",
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user, remote);
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error("Login incorrect.\n");
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exit(1);
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}
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}
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}
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(void) fclose(fp);
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syslog(LOG_INFO, "login from %s as %s", remote, user);
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if (chdir(pwd->pw_dir) < 0) {
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error("No remote directory.\n");
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exit(1);
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}
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(void) write(2, "\0", 1);
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if (port) {
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(void) pipe(pv);
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pid = fork();
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if (pid == -1) {
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error("Try again.\n");
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exit(1);
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}
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if (pid) {
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(void) close(0); (void) close(1); (void) close(2);
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(void) close(f); (void) close(pv[1]);
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readfrom = (1<<s) | (1<<pv[0]);
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ioctl(pv[1], FIONBIO, (char *)&one);
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/* should set s nbio! */
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do {
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ready = readfrom;
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(void) select(16, (fd_set *)&ready,
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(fd_set *)NULL, (fd_set *)NULL,
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(struct timeval *)NULL);
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if (ready & (1<<s)) {
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if (read(s, &sig, 1) <= 0)
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readfrom &= ~(1<<s);
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else
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killpg(pid, sig);
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}
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if (ready & (1<<pv[0])) {
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cc = read(pv[0], buf, sizeof (buf));
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if (cc <= 0) {
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shutdown(s, 1+1);
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readfrom &= ~(1<<pv[0]);
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} else
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(void) write(s, buf, cc);
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}
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} while (readfrom);
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exit(0);
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}
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setpgrp(0, getpid());
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(void) close(s); (void)close(pv[0]);
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dup2(pv[1], 2);
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}
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if (*pwd->pw_shell == '\0')
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pwd->pw_shell = _PATH_BSHELL;
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if (f > 2)
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(void) close(f);
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if (setlogin(pwd->pw_name) < 0)
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syslog(LOG_ERR, "setlogin() failed: %m");
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(void) setgid((gid_t)pwd->pw_gid);
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initgroups(pwd->pw_name, pwd->pw_gid);
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(void) setuid((uid_t)pwd->pw_uid);
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(void)strcat(path, _PATH_DEFPATH);
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environ = envinit;
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strncat(homedir, pwd->pw_dir, sizeof(homedir)-6);
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strncat(shell, pwd->pw_shell, sizeof(shell)-7);
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strncat(username, pwd->pw_name, sizeof(username)-6);
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cp = strrchr(pwd->pw_shell, '/');
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if (cp)
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cp++;
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else
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cp = pwd->pw_shell;
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execl(pwd->pw_shell, cp, "-c", cmdbuf, 0);
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perror(pwd->pw_shell);
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exit(1);
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}
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/*VARARGS1*/
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error(fmt, a1, a2, a3)
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char *fmt;
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int a1, a2, a3;
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{
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char buf[BUFSIZ];
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buf[0] = 1;
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(void) sprintf(buf+1, fmt, a1, a2, a3);
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(void) write(2, buf, strlen(buf));
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}
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getstr(buf, cnt, err)
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char *buf;
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int cnt;
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char *err;
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{
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char c;
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do {
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if (read(0, &c, 1) != 1)
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exit(1);
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*buf++ = c;
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if (--cnt == 0) {
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error("%s too long\n", err);
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exit(1);
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}
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} while (c != 0);
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}
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