From owner-freebsd-hackers  Mon May 26 02:30:29 1997
Return-Path: <owner-hackers>
Received: (from root@localhost)
          by hub.freebsd.org (8.8.5/8.8.5) id CAA08779
          for hackers-outgoing; Mon, 26 May 1997 02:30:29 -0700 (PDT)
Received: from four.wplus.net (four.wplus.net [194.8.160.90])
          by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id CAA08772
          for <hackers@FreeBSD.ORG>; Mon, 26 May 1997 02:30:24 -0700 (PDT)
Received: from himera.wplus.net (himera [194.8.160.126])
          by four.wplus.net (8.8.4/8.8.4) with ESMTP
	  id NAA28613; Mon, 26 May 1997 13:25:34 +0400 (MSD)
Received: (from ptitz@localhost)
          by himera.wplus.net (8.8.4/8.8.4)
	  id NAA24621; Mon, 26 May 1997 13:26:18 +0400 (MSD)
From: Dmitry Mishin <Dmitry.Mishin@wplus.net>
Message-Id: <199705260926.NAA24621@himera.wplus.net>
Subject: Re: Correct way to chroot for shell account users?
To: mrcpu@cdsnet.net (Jaye Mathisen)
Date: Mon, 26 May 1997 13:26:18 +0400 (MSD)
Cc: hackers@FreeBSD.ORG
In-Reply-To: <Pine.NEB.3.95.970525144745.28807A-100000@mail.cdsnet.net> from Jaye Mathisen at "May 25, 97 02:50:55 pm"
X-NCC-RegID: ru.webplus
Organization: WEBPlus Ltd.
X-Mailer: ELM [version 2.4ME+ PL22 (25)]
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: owner-hackers@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

> 
> 
> Anybody got any tips on how to write  a secure shell to exec on login to
> set a users environment to the "right thing".
> 
> (I don't mean a rsh type secure shell, but rather a good secure thing
> to have in /etc/master.passwd that execs the real shell in a chroot'd 
> environment.).
> 
> Any code appreciated as well.  Thanks.
> 
> 
> 
> 

All setup as in wu-ftpd + files in /chroot/./var/
Hope it can help you,
-- 
D.Mishin

*** /usr/src/usr.bin/login/login.c	Mon Aug 28 15:15:54 1995
--- login.c	Mon May 26 13:02:30 1997
***************
*** 130,135 ****
--- 130,137 ----
  #ifdef	SKEY
  	int permit_passwd = 0;
  #endif
+ 	char *pp;
+ 	int is_chrooted = 0;
  
  	(void)signal(SIGALRM, timedout);
  	(void)alarm(timeout);
***************
*** 401,408 ****
--- 403,457 ----
  
  	initgroups(username, pwd->pw_gid);
  
+ 	if (p = strstr(pwd->pw_dir, "/./"))
+ 	{
+ 		chmod(ttyn, 0622);
+ 		pp = strdup(pwd->pw_dir);
+ 		pp[p - pwd->pw_dir] = 0;
+ 		if (chroot(pp)) {
+ 		    syslog(LOG_INFO, "CHROOT error %s: %m", pwd->pw_name); 
+ 		    exit(1);
+ 		}
+ 		is_chrooted = 1;
+ 	
+ 	if (!(pwd = getpwnam(username)))
+ 	{
+ 		syslog(LOG_INFO, "CHROOT user %s isn't defined", username);
+ 		exit(1);
+ 	}
+ 
+ 	
+ 	/* Nothing else left to fail -- really log in. */
+ 	memset((void *)&utmp, 0, sizeof(utmp));
+ 	(void)time(&utmp.ut_time);
+ 	(void)strncpy(utmp.ut_name, username, sizeof(utmp.ut_name));
+ 	if (hostname)
+ 		(void)strncpy(utmp.ut_host, hostname, sizeof(utmp.ut_host));
+ 	(void)strncpy(utmp.ut_line, tty, sizeof(utmp.ut_line));
+ 	login(&utmp);
+ 
+ 	dolastlog(quietlog);
+ 
+ 	/*
+ 	 * Set device protections, depending on what terminal the
+ 	 * user is logged in. This feature is used on Suns to give
+ 	 * console users better privacy.
+ 	 */
+ 	login_fbtab(tty, pwd->pw_uid, pwd->pw_gid);
+ 
+ 	(void)chown(ttyn, pwd->pw_uid,
+ 	    (gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid);
+ 
+ 
+ 	(void)setgid(pwd->pw_gid);
+ 
+ 	initgroups(username, pwd->pw_gid);
+ 
+ 	}
+ 
  	if (*pwd->pw_shell == '\0')
  		pwd->pw_shell = _PATH_BSHELL;
+ 
  
  	/* Destroy environment unless user has requested its preservation. */
  	if (!pflag)