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these setuid scripts work now

    1: #!/usr/bin/perl
    2: 
    3: # Scott Harrison
    4: # SH: November 2, 2000
    5: 
    6: use strict;
    7: 
    8: # This script is a setuid script (chmod 6755; chown root:root).
    9: # It disables nfs/portmap services for a specific user at
   10: # a specific ip address.
   11: 
   12: # Exit codes.  0=ok.  Higher than 0 means something went wrong.
   13: 
   14: # Usage within code
   15: #
   16: # $exitcode=system("/home/httpd/perl/lcnfsoff","NAME","IPADDRESS")/256;
   17: # print "uh-oh" if $exitcode;
   18: 
   19: # Security
   20: $ENV{'PATH'}=""; # Nullify path information.
   21: $ENV{'BASH_ENV'}=""; # Nullify shell environment information.
   22: 
   23: # Do not print error messages if there are command-line arguments
   24: my $noprint=0;
   25: if (@ARGV) {
   26:     $noprint=1;
   27: }
   28: 
   29: # Read in /etc/passwd, and make sure this process is running from user=www
   30: open (IN, "</etc/passwd");
   31: my @lines=<IN>;
   32: close IN;
   33: my $wwwid;
   34: for my $l (@lines) {
   35:     chop $l;
   36:     my @F=split(/\:/,$l);
   37:     if ($F[0] eq 'www') {$wwwid=$F[2];}
   38: }
   39: if ($wwwid!=$<) {
   40:     print("User ID mismatch.  This program must be run as user 'www'\n") unless $noprint;
   41:     exit 1;
   42: }
   43: &disable_root_capability;
   44: 
   45: # Handle case of another lcnfs process
   46: unless (&try_to_lock("/tmp/lock_lcnfs")) {
   47:     print "Error. Too many other simultaneous nfs change requests being made.\n" unless $noprint;
   48:     exit 4;
   49: }
   50: # Gather input.  Should be 2 values (user name, numeric ip address).
   51: my @input;
   52: if (@ARGV==3) {
   53:     @input=@ARGV;
   54: }
   55: elsif (@ARGV) {
   56:     print("Error. This program needs 2 command-line arguments (username, numeric ip address).\n") unless $noprint;
   57:     unlink('/tmp/lock_lcnfs');
   58:     exit 2;
   59: }
   60: else {
   61:     @input=<>;
   62:     if (@input!=2) {
   63: 	print("Error. Two lines should be entered into standard input.\n") unless $noprint;
   64: 	unlink('/tmp/lock_lcnfs');
   65: 	exit 3;
   66:     }
   67:     map {chop} @input;
   68: }
   69: 
   70: my ($username,$ipaddress)=@input;
   71: $username=~/^(\w+)$/;
   72: my $safeusername=$1;
   73: if ($username ne $safeusername) {
   74:     print "Error. The user name specified has invalid characters.\n";
   75:     unlink('/tmp/lock_lcnfs');
   76:     exit 9;
   77: }
   78: 
   79: $ipaddress=~/^([\w|\.]*)$/;
   80: my $safeipaddress=$1;
   81: if ($ipaddress ne $safeipaddress) {
   82:     print "Error. The IP address must be numeric and of the form ##.##.##.##.\n";
   83:     unlink('/tmp/lock_lcnfs');
   84:     exit 8;
   85: }
   86: 
   87: &enable_root_capability;
   88: # Remove entry from /etc/exports
   89: my $exports=`/bin/cat /etc/exports`;
   90: $exports=~s/\/home\/${safeusername}\s*${safeipaddress}.*?\n//g;
   91: # Resynchronize /etc/exports file
   92: open (OUT,">/etc/exports");
   93: print OUT $exports;
   94: close OUT;
   95: system('/usr/sbin/exportfs','-r');
   96: 
   97: # Remove entry from /etc/hosts.allow
   98: my $hostsallow=`/bin/cat /etc/hosts.allow`;
   99: $hostsallow=~s/\# $safeusername\nportmap: $safeipaddress\n//g;
  100: open (OUT,">/etc/hosts.allow");
  101: print OUT $hostsallow;
  102: close OUT;
  103: 
  104: &disable_root_capability;
  105: unlink('/tmp/lock_lcnfs');
  106: exit 0;
  107: 
  108: # ----------------------------------------------------------- have setuid script run as root
  109: sub enable_root_capability {
  110:     if ($wwwid==$>) {
  111: 	($<,$>)=($>,$<);
  112: 	($(,$))=($),$();
  113:     }
  114:     else {
  115: 	# root capability is already enabled
  116:     }
  117:     return $>;
  118: }
  119: 
  120: # ----------------------------------------------------------- have setuid script run as www
  121: sub disable_root_capability {
  122:     if ($wwwid==$<) {
  123: 	($<,$>)=($>,$<);
  124: 	($(,$))=($),$();
  125:     }
  126:     else {
  127: 	# root capability is already disabled
  128:     }
  129: }
  130: 
  131: # ----------------------------------- make sure that another lcnfs process isn't running
  132: sub try_to_lock {
  133:     my ($lockfile)=@_;
  134:     my $currentpid;
  135:     my $lastpid;
  136:     # Do not manipulate lock file as root
  137:     if ($>==0) {
  138: 	return 0;
  139:     }
  140:     # Try to generate lock file.
  141:     # Wait 3 seconds.  If same process id is in
  142:     # lock file, then assume lock file is stale, and
  143:     # go ahead.  If process id's fluctuate, try
  144:     # for a maximum of 10 times.
  145:     for (0..10) {
  146: 	if (-e $lockfile) {
  147: 	    open(LOCK,"<$lockfile");
  148: 	    $currentpid=<LOCK>;
  149: 	    close LOCK;
  150: 	    if ($currentpid==$lastpid) {
  151: 		last;
  152: 	    }
  153: 	    sleep 3;
  154: 	    $lastpid=$currentpid;
  155: 	}
  156: 	else {
  157: 	    last;
  158: 	}
  159: 	if ($_==10) {
  160: 	    return 0;
  161: 	}
  162:     }
  163:     open(LOCK,">$lockfile");
  164:     print LOCK $$;
  165:     close LOCK;
  166:     return 1;
  167: }
  168: 
  169: