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it was working.. now the system exportfs command is still giving
some bad calls

    1: #!/usr/bin/perl
    2: 
    3: # Scott Harrison
    4: # SH: November 2, 2000
    5: 
    6: use strict;
    7: 
    8: # Usage within code
    9: #
   10: # $exitcode=system("/home/httpd/perl/lcuseradd","NAME","IPADDRESS")/256;
   11: # print "uh-oh" if $exitcode;
   12: 
   13: # Security
   14: $ENV{'PATH'}=""; # Nullify path information.
   15: $ENV{'BASH_ENV'}=""; # Nullify shell environment information.
   16: 
   17: # Do not print error messages if there are command-line arguments
   18: my $noprint=0;
   19: if (@ARGV) {
   20:     $noprint=1;
   21: }
   22: 
   23: # Read in /etc/passwd, and make sure this process is running from user=www
   24: open (IN, "</etc/passwd");
   25: my @lines=<IN>;
   26: close IN;
   27: my $wwwid;
   28: for my $l (@lines) {
   29:     chop $l;
   30:     my @F=split(/\:/,$l);
   31:     if ($F[0] eq 'www') {$wwwid=$F[2];}
   32: }
   33: if ($wwwid!=$<) {
   34:     print("User ID mismatch.  This program must be run as user 'www'\n") unless $noprint;
   35:     exit 1;
   36: }
   37: &disable_root_capability;
   38: 
   39: # Handle case of another lcnfs process
   40: unless (&try_to_lock("/tmp/lock_lcnfs")) {
   41:     print "Error. Too many other simultaneous nfs change requests being made.\n" unless $noprint;
   42:     exit 4;
   43: }
   44: # Gather input.  Should be 2 values (user name, numeric ip address).
   45: my @input;
   46: if (@ARGV==3) {
   47:     @input=@ARGV;
   48: }
   49: elsif (@ARGV) {
   50:     print("Error. This program needs 2 command-line arguments (username, numeric ip address).\n") unless $noprint;
   51:     unlink('/tmp/lock_lcnfs');
   52:     exit 2;
   53: }
   54: else {
   55:     @input=<>;
   56:     if (@input!=2) {
   57: 	print("Error. Two lines should be entered into standard input.\n") unless $noprint;
   58: 	unlink('/tmp/lock_lcnfs');
   59: 	exit 3;
   60:     }
   61:     map {chop} @input;
   62: }
   63: 
   64: my ($username,$ipaddress)=@input;
   65: $username=~/^(\w+)$/;
   66: my $safeusername=$1;
   67: if ($username ne $safeusername) {
   68:     print "Error. The user name specified has invalid characters.\n";
   69:     unlink('/tmp/lock_lcnfs');
   70:     exit 9;
   71: }
   72: 
   73: # Read in /etc/passwd, and make sure this process is running from user=www
   74: open (IN, "</etc/passwd");
   75: my @lines=<IN>;
   76: close IN;
   77: my $uid;
   78: my $gid;
   79: for my $l (@lines) {
   80:     chop $l;
   81:     my @F=split(/\:/,$l);
   82:     if ($F[0] eq $safeusername) {$uid=$F[2]; $gid=$F[3];}
   83: }
   84: 
   85: $ipaddress=~/^([\w|\.]*)$/;
   86: my $safeipaddress=$1;
   87: if ($ipaddress ne $safeipaddress) {
   88:     print "Error. The IP address must be numeric and of the form ##.##.##.##.\n";
   89:     unlink('/tmp/lock_lcnfs');
   90:     exit 8;
   91: }
   92: 
   93: &enable_root_capability;
   94: # Make sure nfs is running, if not, start it
   95: my $status=`/etc/rc.d/init.d/nfs status`;
   96: if ($status=~/is stopped/) {
   97:     system('/etc/rc.d/init.d/nfs start','start');
   98: }
   99: 
  100: # Add entry to /etc/exports
  101: my $exports=`/bin/cat /etc/exports`; $exports="\n$exports";
  102: my $entry="/home/$safeusername     $safeipaddress(rw,all_squash,anonuid=$uid,anongid=$gid)\n";
  103: if ($exports=~/\n\/home\/$safeusername\s+$safeipaddress\(rw,all_squash,anonuid=$uid,anongid=$gid\)/) {
  104:     print "Error. /etc/exports already has this entry enabled.\n";
  105:     unlink('/tmp/lock_lcnfs');
  106:     exit 7;
  107: }
  108: open (OUT,">>/etc/exports");
  109: print OUT $entry;
  110: close OUT;
  111: 
  112: # Resynchronize /etc/exports file
  113: system('/usr/sbin/exportfs','-r');
  114: 
  115: # Add entry /etc/hosts.allow
  116: my $hostsallow=`/bin/cat /etc/hosts.allow`;
  117: my $entry="# $safeusername\nportmap: $safeipaddress\n";
  118: if ($hostsallow=~/\n\# $safeusername\s*\nportmap: $safeipaddress\n/) {
  119:     print "Error. /etc/hosts already has this entry enabled.\n";
  120:     unlink('/tmp/lock_lcnfs');
  121:     exit 6;
  122: }
  123: open (OUT,">>/etc/hosts.allow");
  124: print OUT $entry;
  125: close OUT;
  126: 
  127: &disable_root_capability;
  128: unlink('/tmp/lock_lcnfs');
  129: exit 0;
  130: 
  131: # ----------------------------------------------------------- have setuid script run as root
  132: sub enable_root_capability {
  133:     if ($wwwid==$>) {
  134: 	($<,$>)=($>,$<);
  135: 	($(,$))=($),$();
  136:     }
  137:     else {
  138: 	# root capability is already enabled
  139:     }
  140:     return $>;
  141: }
  142: 
  143: # ----------------------------------------------------------- have setuid script run as www
  144: sub disable_root_capability {
  145:     if ($wwwid==$<) {
  146: 	($<,$>)=($>,$<);
  147: 	($(,$))=($),$();
  148:     }
  149:     else {
  150: 	# root capability is already disabled
  151:     }
  152: }
  153: 
  154: # ----------------------------------- make sure that another lcnfs process isn't running
  155: sub try_to_lock {
  156:     my ($lockfile)=@_;
  157:     my $currentpid;
  158:     my $lastpid;
  159:     # Do not manipulate lock file as root
  160:     if ($>==0) {
  161: 	return 0;
  162:     }
  163:     # Try to generate lock file.
  164:     # Wait 3 seconds.  If same process id is in
  165:     # lock file, then assume lock file is stale, and
  166:     # go ahead.  If process id's fluctuate, try
  167:     # for a maximum of 10 times.
  168:     for (0..10) {
  169: 	if (-e $lockfile) {
  170: 	    open(LOCK,"<$lockfile");
  171: 	    $currentpid=<LOCK>;
  172: 	    close LOCK;
  173: 	    if ($currentpid==$lastpid) {
  174: 		last;
  175: 	    }
  176: 	    sleep 3;
  177: 	    $lastpid=$currentpid;
  178: 	}
  179: 	else {
  180: 	    last;
  181: 	}
  182: 	if ($_==10) {
  183: 	    return 0;
  184: 	}
  185:     }
  186:     open(LOCK,">$lockfile");
  187:     print LOCK $$;
  188:     close LOCK;
  189:     return 1;
  190: }