Return to lcuseradd CVS log

Up to [LON-CAPA] / loncom

more error catching and commenting.  lcuseradd should be complete, but
I've yet to test the script or give a careful look-through. -Scott

    1: #!/usr/bin/perl
    2: #
    3: # lcuseradd
    4: #
    5: # Scott Harrison
    6: # October 27, 2000
    7: 
    8: use strict;
    9: 
   10: # This script is a setuid script that should
   11: # be run by user 'www'.  It creates a /home/USERNAME directory
   12: # as well as a /home/USERNAME/public_html directory.
   13: # It adds user entries to
   14: # /etc/passwd and /etc/groups.
   15: # Passwords are set with lcpasswd.
   16: # www becomes a member of this user group.
   17: 
   18: # Standard input usage
   19: # First line is USERNAME
   20: # Second line is PASSWORD
   21: # Third line is PASSWORD
   22: 
   23: # Valid passwords must consist of the
   24: # ascii characters within the inclusive
   25: # range of 0x20 (32) to 0x7E (126).
   26: # These characters are:
   27: # SPACE and
   28: # !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO
   29: # PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
   30: 
   31: # Valid user names must consist of ascii
   32: # characters that are alphabetical characters
   33: # (A-Z,a-z), numeric (0-9), or the underscore
   34: # mark (_). (Essentially, the perl regex \w).
   35: 
   36: # Command-line arguments [USERNAME] [PASSWORD] [PASSWORD]
   37: # Yes, but be very careful here (don't pass shell commands)
   38: # and this is only supported to allow perl-system calls.
   39: 
   40: # Usage within code
   41: #
   42: # $exitcode=system("/home/httpd/perl/lcuseradd","NAME","PASSWORD1","PASSWORD2")/256;
   43: # print "uh-oh" if $exitcode;
   44: 
   45: # These are the exit codes.
   46: 
   47: # Security
   48: $ENV{'PATH'}=""; # Nullify path information.
   49: $ENV{'BASH_ENV'}=""; # Nullify shell environment information.
   50: 
   51: # Do not print error messages if there are command-line arguments
   52: my $noprint=0;
   53: if (@ARGV) {
   54:     $noprint=1;
   55: }
   56: 
   57: # Read in /etc/passwd, and make sure this process is running from user=www
   58: open (IN, "</etc/passwd");
   59: my @lines=<IN>;
   60: close IN;
   61: my $wwwid;
   62: for my $l (@lines) {
   63:     chop $l;
   64:     my @F=split(/\:/,$l);
   65:     if ($F[0] eq 'www') {$wwwid=$F[2];}
   66: }
   67: if ($wwwid!=$<) {
   68:     print("User ID mismatch.  This program must be run as user 'www'\n") unless $noprint;
   69:     exit 1;
   70: }
   71: &disable_root_capability;
   72: 
   73: # Handle case of another lcpasswd process
   74: unless (&try_to_lock("/tmp/lock_lcpasswd")) {
   75:     print "Error. Too many other simultaneous password change requests being made.\n" unless $noprint;
   76:     exit 4;
   77: }
   78: 
   79: # Gather input.  Should be 3 values (user name, password 1, password 2).
   80: my @input;
   81: if (@ARGV==3) {
   82:     @input=@ARGV;
   83: }
   84: elsif (@ARGV) {
   85:     print("Error. This program needs 3 command-line arguments (username, password 1, password 2).\n") unless $noprint;
   86:     unlink('/tmp/lock_lcpasswd');
   87:     exit 2;
   88: }
   89: else {
   90:     @input=<>;
   91:     if (@input!=3) {
   92: 	print("Error. Three lines should be entered into standard input.\n") unless $noprint;
   93: 	unlink('/tmp/lock_lcpasswd');
   94: 	exit 3;
   95:     }
   96:     map {chop} @input;
   97: }
   98: 
   99: my ($username,$password1,$password2)=@input;
  100: $username=~/^(\w+)$/;
  101: my $safeusername=$1;
  102: if ($username ne $safeusername) {
  103:     print "Error. The user name specified has invalid characters.\n";
  104:     unlink('/tmp/lock_lcpasswd');
  105:     exit 9;
  106: }
  107: my $pbad=0;
  108: map {if (($_<32)&&($_>126)){$pbad=1;}} (split(//,$oldpwd));
  109: map {if (($_<32)&&($_>126)){$pbad=1;}} (split(//,$newpwd));
  110: if ($pbad) {
  111:     print "Error. A password entry had an invalid character.\n";
  112:     unlink('/tmp/lock_lcpasswd');
  113:     exit 10;
  114: }
  115: 
  116: # Only add user if we can create a brand new home directory (/home/username).
  117: if (-e "/home/$safeusername") {
  118:     print "Error. User already exists.\n" unless $noprint;
  119:     unlink('/tmp/lock_lcpasswd');
  120:     exit 8;
  121: }
  122: 
  123: # Only add user if the two password arguments match.
  124: if ($password1 ne $password2) {
  125:     print "Error. Password mismatch.\n" unless $noprint;
  126:     unlink('/tmp/lock_lcpasswd');
  127:     exit 7;
  128: }
  129: 
  130: &enable_root_capability;
  131: 
  132: # Add user entry to /etc/passwd and /etc/groups in such
  133: # a way that www is a member of the user-specific group
  134: 
  135: if (system('/usr/sbin/useradd','-c','LON-CAPA user',$safeusername)) {
  136:     print "Error.  Something went wrong with the addition of user \"$safeusername\".\n" unless $noprint;
  137:     unlink('/tmp/lock_lcpasswd');
  138:     exit 5;
  139: }
  140: 
  141: # Make www a member of that user group.
  142: if (system('/usr/sbin/usermod','-G',$safeusername,'www')) {
  143:     print "Error. Could not make www a member of the group \"$safeusername\".\n" unless $noprint;
  144:     unlink('/tmp/lock_lcpasswd');
  145:     exit 6;
  146: }
  147: 
  148: # Set password with lcpasswd-style algorithm (which creates smbpasswd entry).
  149: # I cannot place a direct shell call to lcpasswd since I have to allow
  150: # for crazy characters in the password, and the setuid environment of perl
  151: # requires me to make everything safe.
  152: 
  153: my $pbad=0;
  154: map {if (($_<32)&&($_>126)){$pbad=1;}} (split(//,$oldpwd));
  155: map {if (($_<32)&&($_>126)){$pbad=1;}} (split(//,$newpwd));
  156: if ($pbad) {
  157:     print "Error. A password entry had an invalid character.\n";
  158:     unlink('/tmp/lock_lcpasswd');
  159:     exit 10;
  160: }
  161: 
  162: # Grab the line corresponding to username
  163: my ($userid,$useroldcryptpwd);
  164: my @F; my @U;
  165: for my $l (@lines) {
  166:     @F=split(/\:/,$l);
  167:     if ($F[0] eq $username) {($userid,$useroldcryptpwd)=($F[2],$F[1]); @U=@F;}
  168: }
  169: 
  170: # Verify existence of user
  171: if (!defined($userid)) {
  172:     print "Error. User $username does not exist.\n" unless $noprint;
  173:     unlink('/tmp/lock_lcpasswd');
  174:     exit 5;
  175: }
  176: 
  177: # Verify password entry
  178: if (crypt($oldpwd,$useroldcryptpwd) ne $useroldcryptpwd) {
  179:     print "Error. Invalid entry of current password.\n" unless $noprint;
  180:     unlink('/tmp/lock_lcpasswd');
  181:     exit 6;
  182: }
  183: 
  184: # Construct new password entry (random salt)
  185: my $newcryptpwd=crypt($newpwd,(join '', ('.', '/', 0..9, 'A'..'Z', 'a'..'z')[rand 64, rand 64]));
  186: $U[1]=$newcryptpwd;
  187: my $userline=join(':',@U);
  188: my $rootid=&enable_root_capability;
  189: if ($rootid!=0) {
  190:     print "Error.  Root was not successfully enabled.\n" unless $noprint;
  191:     unlink('/tmp/lock_lcpasswd');
  192:     exit 7;
  193: }
  194: open PASSWORDFILE, '>/etc/passwd' or (print("Error.  Cannot open /etc/passwd.\n") && unlink('/tmp/lock_lcpasswd') && exit(8));
  195: for my $l (@lines) {
  196:     @F=split(/\:/,$l);
  197:     if ($F[0] eq $username) {print PASSWORDFILE "$userline\n";}
  198:     else {print PASSWORDFILE "$l\n";}
  199: }
  200: close PASSWORDFILE;
  201: 
  202: ($>,$<)=(0,0); # fool smbpasswd here to think this is not a setuid environment
  203: unless (-e '/etc/smbpasswd') {
  204:     open (OUT,'>/etc/smbpasswd'); close OUT;
  205: }
  206: my $smbexist=0;
  207: open (IN, '</etc/smbpasswd');
  208: my @lines=<IN>;
  209: close IN;
  210: for my $l (@lines) {
  211:     chop $l;
  212:     my @F=split(/\:/,$l);
  213:     if ($F[0] eq $username) {$smbexist=1;}
  214: }
  215: unless ($smbexist) {
  216:     open(OUT,'>>/etc/smbpasswd');
  217:     print OUT join(':',($safeusername,$userid,'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX','','/home/'.$safeusername,'/bin/bash')) . "\n";
  218:     close OUT;
  219: }
  220: open(OUT,"|/usr/bin/smbpasswd -s $safeusername>/dev/null");
  221: print OUT $newpwd; print OUT "\n";
  222: print OUT $newpwd; print OUT "\n";
  223: close OUT;
  224: $<=$wwwid; # unfool the program
  225: 
  226: # Make final modifications to the user directory.
  227: # Add a public_html file with a stand-in index.html file.
  228: 
  229: mkdir "/home/$safeusername/public_html",0750;
  230: # chmod -R
  231: open OUT,">/home/$safeusername/public_html";
  232: print OUT<<END;
  233: <HTML>
  234: <HEAD>
  235: <TITLE>$safeusername</TITLE>
  236: </HEAD>
  237: <BODY>
  238: <H1>$safeusername</H1>
  239: <P>
  240: Learning Online Network
  241: </P>
  242: <P>
  243: This area provides for:
  244: </P>
  245: <UL>
  246: <LI>resource construction
  247: <LI>resource publication
  248: <LI>record-keeping
  249: </UL>
  250: </BODY>
  251: </HTML>
  252: END
  253: close OUT;
  254: 
  255: &disable_root_capability;
  256: unlink('/tmp/lock_lcpasswd');
  257: exit 0;
  258: 
  259: # ----------------------------------------------------------- have setuid script run as root
  260: sub enable_root_capability {
  261:     if ($wwwid==$>) {
  262: 	($<,$>)=($>,$<);
  263: 	($(,$))=($),$();
  264:     }
  265:     else {
  266: 	# root capability is already enabled
  267:     }
  268:     return $>;
  269: }
  270: 
  271: # ----------------------------------------------------------- have setuid script run as www
  272: sub disable_root_capability {
  273:     if ($wwwid==$<) {
  274: 	($<,$>)=($>,$<);
  275: 	($(,$))=($),$();
  276:     }
  277:     else {
  278: 	# root capability is already disabled
  279:     }
  280: }
  281: 
  282: # ----------------------------------- make sure that another lcpasswd process isn't running
  283: sub try_to_lock {
  284:     my ($lockfile)=@_;
  285:     my $currentpid;
  286:     my $lastpid;
  287:     # Do not manipulate lock file as root
  288:     if ($>==0) {
  289: 	return 0;
  290:     }
  291:     # Try to generate lock file.
  292:     # Wait 3 seconds.  If same process id is in
  293:     # lock file, then assume lock file is stale, and
  294:     # go ahead.  If process id's fluctuate, try
  295:     # for a maximum of 10 times.
  296:     for (0..10) {
  297: 	if (-e $lockfile) {
  298: 	    open(LOCK,"<$lockfile");
  299: 	    $currentpid=<LOCK>;
  300: 	    close LOCK;
  301: 	    if ($currentpid==$lastpid) {
  302: 		last;
  303: 	    }
  304: 	    sleep 3;
  305: 	    $lastpid=$currentpid;
  306: 	}
  307: 	else {
  308: 	    last;
  309: 	}
  310: 	if ($_==10) {
  311: 	    return 0;
  312: 	}
  313:     }
  314:     open(LOCK,">$lockfile");
  315:     print LOCK $$;
  316:     close LOCK;
  317:     return 1;
  318: }