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I'm updating the error code listings in the comments.

    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 needs 3 command-line arguments (username, old password, new password)."),
   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: #   (9,"Error. The user name specified has invalid characters."),
   60: #   (10,"Error. A password entry had an invalid character.") )
   61: 
   62: # Security
   63: $ENV{'PATH'}='/bin:/usr/bin'; # Nullify path information except for what smbpasswd needs
   64: $ENV{'BASH_ENV'}=''; # Nullify shell environment information.
   65: 
   66: # Do not print error messages if there are command-line arguments
   67: my $noprint=0;
   68: if (@ARGV) {
   69:     $noprint=1;
   70: }
   71: 
   72: # Read in /etc/passwd, and make sure this process is running from user=www
   73: open (IN, '</etc/passwd');
   74: my @lines=<IN>;
   75: close IN;
   76: my $wwwid;
   77: for my $l (@lines) {
   78:     chop $l;
   79:     my @F=split(/\:/,$l);
   80:     if ($F[0] eq 'www') {$wwwid=$F[2];}
   81: }
   82: if ($wwwid!=$<) {
   83:     print("User ID mismatch.  This program must be run as user 'www'\n") unless $noprint;
   84:     exit 1;
   85: }
   86: &disable_root_capability;
   87: 
   88: # Handle case of another lcpasswd process
   89: unless (&try_to_lock('/tmp/lock_lcpasswd')) {
   90:     print "Error. Too many other simultaneous password change requests being made.\n" unless $noprint;
   91:     exit 4;
   92: }
   93: 
   94: # Gather input.  Should only be 3 values.
   95: my @input;
   96: if (@ARGV==3) {
   97:     @input=@ARGV;
   98: }
   99: elsif (@ARGV) {
  100:     print("Error. This program needs 3 command-line arguments (username, old password, new password).\n") unless $noprint;
  101:     unlink('/tmp/lock_lcpasswd');
  102:     exit 2;
  103: }
  104: else {
  105:     @input=<>;
  106:     if (@input!=3) {
  107: 	print("Error. Three lines need to be entered into standard input.\n") unless $noprint;
  108: 	unlink('/tmp/lock_lcpasswd');
  109: 	exit 3;
  110:     }
  111:     map {chop} @input;
  112: }
  113: 
  114: my ($username,$oldpwd,$newpwd)=@input;
  115: $username=~/^(\w+)$/;
  116: my $safeusername=$1;
  117: if ($username ne $safeusername) {
  118:     print "Error. The user name specified has invalid characters.\n";
  119:     unlink('/tmp/lock_lcpasswd');
  120:     exit 9;
  121: }
  122: my $pbad=0;
  123: map {if (($_<32)&&($_>126)){$pbad=1;}} (split(//,$oldpwd));
  124: map {if (($_<32)&&($_>126)){$pbad=1;}} (split(//,$newpwd));
  125: if ($pbad) {
  126:     print "Error. A password entry had an invalid character.\n";
  127:     unlink('/tmp/lock_lcpasswd');
  128:     exit 10;
  129: }
  130: 
  131: # Grab the line corresponding to username
  132: my ($userid,$useroldcryptpwd);
  133: my @F; my @U;
  134: for my $l (@lines) {
  135:     @F=split(/\:/,$l);
  136:     if ($F[0] eq $username) {($userid,$useroldcryptpwd)=($F[2],$F[1]); @U=@F;}
  137: }
  138: 
  139: # Verify existence of user
  140: if (!defined($userid)) {
  141:     print "Error. User $username does not exist.\n" unless $noprint;
  142:     unlink('/tmp/lock_lcpasswd');
  143:     exit 5;
  144: }
  145: 
  146: # Verify password entry
  147: if (crypt($oldpwd,$useroldcryptpwd) ne $useroldcryptpwd) {
  148:     print "Error. Invalid entry of current password.\n" unless $noprint;
  149:     unlink('/tmp/lock_lcpasswd');
  150:     exit 6;
  151: }
  152: 
  153: # Construct new password entry (random salt)
  154: my $newcryptpwd=crypt($newpwd,(join '', ('.', '/', 0..9, 'A'..'Z', 'a'..'z')[rand 64, rand 64]));
  155: $U[1]=$newcryptpwd;
  156: my $userline=join(':',@U);
  157: my $rootid=&enable_root_capability;
  158: if ($rootid!=0) {
  159:     print "Error.  Root was not successfully enabled.\n" unless $noprint;
  160:     unlink('/tmp/lock_lcpasswd');
  161:     exit 7;
  162: }
  163: open PASSWORDFILE, '>/etc/passwd' or (print("Error.  Cannot open /etc/passwd.\n") && unlink('/tmp/lock_lcpasswd') && exit(8));
  164: for my $l (@lines) {
  165:     @F=split(/\:/,$l);
  166:     if ($F[0] eq $username) {print PASSWORDFILE "$userline\n";}
  167:     else {print PASSWORDFILE "$l\n";}
  168: }
  169: close PASSWORDFILE;
  170: 
  171: ($>,$<)=(0,0); # fool smbpasswd here to think this is not a setuid environment
  172: unless (-e '/etc/smbpasswd') {
  173:     open (OUT,'>/etc/smbpasswd'); close OUT;
  174: }
  175: my $smbexist=0;
  176: open (IN, '</etc/smbpasswd');
  177: my @lines=<IN>;
  178: close IN;
  179: for my $l (@lines) {
  180:     chop $l;
  181:     my @F=split(/\:/,$l);
  182:     if ($F[0] eq $username) {$smbexist=1;}
  183: }
  184: unless ($smbexist) {
  185:     open(OUT,'>>/etc/smbpasswd');
  186:     print OUT join(':',($safeusername,$userid,'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX','','/home/'.$safeusername,'/bin/bash')) . "\n";
  187:     close OUT;
  188: }
  189: open(OUT,"|/usr/bin/smbpasswd -s $safeusername>/dev/null");
  190: print OUT $newpwd; print OUT "\n";
  191: print OUT $newpwd; print OUT "\n";
  192: close OUT;
  193: $<=$wwwid; # unfool the program
  194: &disable_root_capability;
  195: unlink('/tmp/lock_lcpasswd');
  196: exit 0;
  197: 
  198: # ----------------------------------------------------------- have setuid script run as root
  199: sub enable_root_capability {
  200:     if ($wwwid==$>) {
  201: 	($<,$>)=($>,$<);
  202: 	($(,$))=($),$();
  203:     }
  204:     else {
  205: 	# root capability is already enabled
  206:     }
  207:     return $>;
  208: }
  209: 
  210: # ----------------------------------------------------------- have setuid script run as www
  211: sub disable_root_capability {
  212:     if ($wwwid==$<) {
  213: 	($<,$>)=($>,$<);
  214: 	($(,$))=($),$();
  215:     }
  216:     else {
  217: 	# root capability is already disabled
  218:     }
  219: }
  220: 
  221: # ----------------------------------- make sure that another lcpasswd process isn't running
  222: sub try_to_lock {
  223:     my ($lockfile)=@_;
  224:     my $currentpid;
  225:     my $lastpid;
  226:     # Do not manipulate lock file as root
  227:     if ($>==0) {
  228: 	return 0;
  229:     }
  230:     # Try to generate lock file.
  231:     # Wait 3 seconds.  If same process id is in
  232:     # lock file, then assume lock file is stale, and
  233:     # go ahead.  If process id's fluctuate, try
  234:     # for a maximum of 10 times.
  235:     for (0..10) {
  236: 	if (-e $lockfile) {
  237: 	    open(LOCK,"<$lockfile");
  238: 	    $currentpid=<LOCK>;
  239: 	    close LOCK;
  240: 	    if ($currentpid==$lastpid) {
  241: 		last;
  242: 	    }
  243: 	    sleep 3;
  244: 	    $lastpid=$currentpid;
  245: 	}
  246: 	else {
  247: 	    last;
  248: 	}
  249: 	if ($_==10) {
  250: 	    return 0;
  251: 	}
  252:     }
  253:     open(LOCK,">$lockfile");
  254:     print LOCK $$;
  255:     close LOCK;
  256:     return 1;
  257: }