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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: # lcpasswd
    4: #
    5: # Scott Harrison
    6: # SH: October 27, 2000
    7: # SH: October 28, 2000
    8: 
    9: use strict;
   10: 
   11: # This script is a setuid script that should
   12: # be run by user 'www'.  This script allows
   13: # for synchronous entry of passwords into
   14: # both the /etc/passwd and the /etc/smbpasswd
   15: # files.
   16: 
   17: # This script works under the same process control mechanism
   18: # as lcuseradd and lcpasswd, to make sure that only one of these
   19: # processes is running at any one time on the system.
   20: 
   21: # Standard input usage
   22: # First line is USERNAME
   23: # Second line is CURRENT PASSWORD
   24: # Third line is NEW PASSWORD
   25: 
   26: # Valid passwords must consist of the
   27: # ascii characters within the inclusive
   28: # range of 0x20 (32) to 0x7E (126).
   29: # These characters are:
   30: # SPACE and
   31: # !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO
   32: # PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
   33: 
   34: # Valid user names must consist of ascii
   35: # characters that are alphabetical characters
   36: # (A-Z,a-z), numeric (0-9), or the underscore
   37: # mark (_). (Essentially, the perl regex \w).
   38: 
   39: # Command-line arguments
   40: # Yes, but be very careful here (don't pass shell commands)
   41: # and this is only supported to allow perl-system calls.
   42: 
   43: # Usage within code
   44: # Note: NEVER run as system("/home/httpd/perl/lcpasswd NAME OLDPWD NEWPWD")
   45: #
   46: # $exitcode=system("/home/httpd/perl/lcpasswd","NAME","OLDPWD","NEWPWD")/256;
   47: # print "uh-oh" if $exitcode;
   48: 
   49: # These are the exit codes.
   50: # ( (0,"ok"),
   51: #   (1,"User ID mismatch.  This program must be run as user 'www'"),
   52: #   (2,"Error. This program does not accept command-line arguments."),
   53: #   (3,"Error. Three lines need to be entered into standard input."),
   54: #   (4,"Error. Too many other simultaneous password change requests being made."),
   55: #   (5,"Error. User $username does not exist."),
   56: #   (6,"Error. Invalid entry of current password."),
   57: #   (7,"Error.  Root was not successfully enabled."),
   58: #   (8,"Error.  Cannot open /etc/passwd.") )
   59: 
   60: # Security
   61: $ENV{'PATH'}='/bin:/usr/bin'; # Nullify path information except for what smbpasswd needs
   62: $ENV{'BASH_ENV'}=''; # Nullify shell environment information.
   63: 
   64: # Do not print error messages if there are command-line arguments
   65: my $noprint=0;
   66: if (@ARGV) {
   67:     $noprint=1;
   68: }
   69: 
   70: # Read in /etc/passwd, and make sure this process is running from user=www
   71: open (IN, '</etc/passwd');
   72: my @lines=<IN>;
   73: close IN;
   74: my $wwwid;
   75: for my $l (@lines) {
   76:     chop $l;
   77:     my @F=split(/\:/,$l);
   78:     if ($F[0] eq 'www') {$wwwid=$F[2];}
   79: }
   80: if ($wwwid!=$<) {
   81:     print("User ID mismatch.  This program must be run as user 'www'\n") unless $noprint;
   82:     exit 1;
   83: }
   84: &disable_root_capability;
   85: 
   86: # Handle case of another lcpasswd process
   87: unless (&try_to_lock('/tmp/lock_lcpasswd')) {
   88:     print "Error. Too many other simultaneous password change requests being made.\n" unless $noprint;
   89:     exit 4;
   90: }
   91: 
   92: # Gather input.  Should only be 3 values.
   93: my @input;
   94: if (@ARGV==3) {
   95:     @input=@ARGV;
   96: }
   97: elsif (@ARGV) {
   98:     print("Error. This program needs 3 command-line arguments (username, old password, new password).\n") unless $noprint;
   99:     unlink('/tmp/lock_lcpasswd');
  100:     exit 2;
  101: }
  102: else {
  103:     @input=<>;
  104:     if (@input!=3) {
  105: 	print("Error. Three lines need to be entered into standard input.\n") unless $noprint;
  106: 	unlink('/tmp/lock_lcpasswd');
  107: 	exit 3;
  108:     }
  109:     map {chop} @input;
  110: }
  111: 
  112: my ($username,$oldpwd,$newpwd)=@input;
  113: $username=~/^(\w+)$/;
  114: my $safeusername=$1;
  115: if ($username ne $safeusername) {
  116:     print "Error. The user name specified has invalid characters.\n";
  117:     unlink('/tmp/lock_lcpasswd');
  118:     exit 9;
  119: }
  120: my $pbad=0;
  121: map {if (($_<32)&&($_>126)){$pbad=1;}} (split(//,$oldpwd));
  122: map {if (($_<32)&&($_>126)){$pbad=1;}} (split(//,$newpwd));
  123: if ($pbad) {
  124:     print "Error. A password entry had an invalid character.\n";
  125:     unlink('/tmp/lock_lcpasswd');
  126:     exit 10;
  127: }
  128: 
  129: # Grab the line corresponding to username
  130: my ($userid,$useroldcryptpwd);
  131: my @F; my @U;
  132: for my $l (@lines) {
  133:     @F=split(/\:/,$l);
  134:     if ($F[0] eq $username) {($userid,$useroldcryptpwd)=($F[2],$F[1]); @U=@F;}
  135: }
  136: 
  137: # Verify existence of user
  138: if (!defined($userid)) {
  139:     print "Error. User $username does not exist.\n" unless $noprint;
  140:     unlink('/tmp/lock_lcpasswd');
  141:     exit 5;
  142: }
  143: 
  144: # Verify password entry
  145: if (crypt($oldpwd,$useroldcryptpwd) ne $useroldcryptpwd) {
  146:     print "Error. Invalid entry of current password.\n" unless $noprint;
  147:     unlink('/tmp/lock_lcpasswd');
  148:     exit 6;
  149: }
  150: 
  151: # Construct new password entry (random salt)
  152: my $newcryptpwd=crypt($newpwd,(join '', ('.', '/', 0..9, 'A'..'Z', 'a'..'z')[rand 64, rand 64]));
  153: $U[1]=$newcryptpwd;
  154: my $userline=join(':',@U);
  155: my $rootid=&enable_root_capability;
  156: if ($rootid!=0) {
  157:     print "Error.  Root was not successfully enabled.\n" unless $noprint;
  158:     unlink('/tmp/lock_lcpasswd');
  159:     exit 7;
  160: }
  161: open PASSWORDFILE, '>/etc/passwd' or (print("Error.  Cannot open /etc/passwd.\n") && unlink('/tmp/lock_lcpasswd') && exit(8));
  162: for my $l (@lines) {
  163:     @F=split(/\:/,$l);
  164:     if ($F[0] eq $username) {print PASSWORDFILE "$userline\n";}
  165:     else {print PASSWORDFILE "$l\n";}
  166: }
  167: close PASSWORDFILE;
  168: 
  169: ($>,$<)=(0,0); # fool smbpasswd here to think this is not a setuid environment
  170: unless (-e '/etc/smbpasswd') {
  171:     open (OUT,'>/etc/smbpasswd'); close OUT;
  172: }
  173: my $smbexist=0;
  174: open (IN, '</etc/smbpasswd');
  175: my @lines=<IN>;
  176: close IN;
  177: for my $l (@lines) {
  178:     chop $l;
  179:     my @F=split(/\:/,$l);
  180:     if ($F[0] eq $username) {$smbexist=1;}
  181: }
  182: unless ($smbexist) {
  183:     open(OUT,'>>/etc/smbpasswd');
  184:     print OUT join(':',($safeusername,$userid,'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX','','/home/'.$safeusername,'/bin/bash')) . "\n";
  185:     close OUT;
  186: }
  187: open(OUT,"|/usr/bin/smbpasswd -s $safeusername>/dev/null");
  188: print OUT $newpwd; print OUT "\n";
  189: print OUT $newpwd; print OUT "\n";
  190: close OUT;
  191: $<=$wwwid; # unfool the program
  192: &disable_root_capability;
  193: unlink('/tmp/lock_lcpasswd');
  194: exit 0;
  195: 
  196: # ----------------------------------------------------------- have setuid script run as root
  197: sub enable_root_capability {
  198:     if ($wwwid==$>) {
  199: 	($<,$>)=($>,$<);
  200: 	($(,$))=($),$();
  201:     }
  202:     else {
  203: 	# root capability is already enabled
  204:     }
  205:     return $>;
  206: }
  207: 
  208: # ----------------------------------------------------------- have setuid script run as www
  209: sub disable_root_capability {
  210:     if ($wwwid==$<) {
  211: 	($<,$>)=($>,$<);
  212: 	($(,$))=($),$();
  213:     }
  214:     else {
  215: 	# root capability is already disabled
  216:     }
  217: }
  218: 
  219: # ----------------------------------- make sure that another lcpasswd process isn't running
  220: sub try_to_lock {
  221:     my ($lockfile)=@_;
  222:     my $currentpid;
  223:     my $lastpid;
  224:     # Do not manipulate lock file as root
  225:     if ($>==0) {
  226: 	return 0;
  227:     }
  228:     # Try to generate lock file.
  229:     # Wait 3 seconds.  If same process id is in
  230:     # lock file, then assume lock file is stale, and
  231:     # go ahead.  If process id's fluctuate, try
  232:     # for a maximum of 10 times.
  233:     for (0..10) {
  234: 	if (-e $lockfile) {
  235: 	    open(LOCK,"<$lockfile");
  236: 	    $currentpid=<LOCK>;
  237: 	    close LOCK;
  238: 	    if ($currentpid==$lastpid) {
  239: 		last;
  240: 	    }
  241: 	    sleep 3;
  242: 	    $lastpid=$currentpid;
  243: 	}
  244: 	else {
  245: 	    last;
  246: 	}
  247: 	if ($_==10) {
  248: 	    return 0;
  249: 	}
  250:     }
  251:     open(LOCK,">$lockfile");
  252:     print LOCK $$;
  253:     close LOCK;
  254:     return 1;
  255: }