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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 enables 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: # Usage within code
   14: #
   15: # $exitcode=system("/home/httpd/perl/lcuseradd","NAME","IPADDRESS")/256;
   16: # print "uh-oh" if $exitcode;
   17: 
   18: # Security
   19: $ENV{'PATH'}=""; # Nullify path information.
   20: $ENV{'BASH_ENV'}=""; # Nullify shell environment information.
   21: 
   22: # Do not print error messages if there are command-line arguments
   23: my $noprint=0;
   24: if (@ARGV) {
   25:     $noprint=1;
   26: }
   27: 
   28: # Read in /etc/passwd, and make sure this process is running from user=www
   29: open (IN, "</etc/passwd");
   30: my @lines=<IN>;
   31: close IN;
   32: my $wwwid;
   33: for my $l (@lines) {
   34:     chop $l;
   35:     my @F=split(/\:/,$l);
   36:     if ($F[0] eq 'www') {$wwwid=$F[2];}
   37: }
   38: if ($wwwid!=$<) {
   39:     print("User ID mismatch.  This program must be run as user 'www'\n") unless $noprint;
   40:     exit 1;
   41: }
   42: &disable_root_capability;
   43: 
   44: # Handle case of another lcnfs process
   45: unless (&try_to_lock("/tmp/lock_lcnfs")) {
   46:     print "Error. Too many other simultaneous nfs change requests being made.\n" unless $noprint;
   47:     exit 4;
   48: }
   49: # Gather input.  Should be 2 values (user name, numeric ip address).
   50: my @input;
   51: if (@ARGV==3) {
   52:     @input=@ARGV;
   53: }
   54: elsif (@ARGV) {
   55:     print("Error. This program needs 2 command-line arguments (username, numeric ip address).\n") unless $noprint;
   56:     unlink('/tmp/lock_lcnfs');
   57:     exit 2;
   58: }
   59: else {
   60:     @input=<>;
   61:     if (@input!=2) {
   62: 	print("Error. Two lines should be entered into standard input.\n") unless $noprint;
   63: 	unlink('/tmp/lock_lcnfs');
   64: 	exit 3;
   65:     }
   66:     map {chop} @input;
   67: }
   68: 
   69: my ($username,$ipaddress)=@input;
   70: $username=~/^(\w+)$/;
   71: my $safeusername=$1;
   72: if ($username ne $safeusername) {
   73:     print "Error. The user name specified has invalid characters.\n";
   74:     unlink('/tmp/lock_lcnfs');
   75:     exit 9;
   76: }
   77: 
   78: # Read in /etc/passwd, and make sure this process is running from user=www
   79: open (IN, "</etc/passwd");
   80: my @lines=<IN>;
   81: close IN;
   82: my $uid;
   83: my $gid;
   84: for my $l (@lines) {
   85:     chop $l;
   86:     my @F=split(/\:/,$l);
   87:     if ($F[0] eq $safeusername) {$uid=$F[2]; $gid=$F[3];}
   88: }
   89: 
   90: $ipaddress=~/^([\w|\.]*)$/;
   91: my $safeipaddress=$1;
   92: if ($ipaddress ne $safeipaddress) {
   93:     print "Error. The IP address must be numeric and of the form ##.##.##.##.\n";
   94:     unlink('/tmp/lock_lcnfs');
   95:     exit 8;
   96: }
   97: 
   98: &enable_root_capability;
   99: # Make sure nfs is running, if not, start it
  100: my $status=`/etc/rc.d/init.d/nfs status`;
  101: if ($status=~/is stopped/) {
  102:     system('/etc/rc.d/init.d/nfs start','start');
  103: }
  104: 
  105: # Add entry to /etc/exports
  106: my $exports=`/bin/cat /etc/exports`; $exports="\n$exports";
  107: my $entry="/home/$safeusername     $safeipaddress(rw,all_squash,anonuid=$uid,anongid=$gid)\n";
  108: if ($exports=~/\n\/home\/$safeusername\s+$safeipaddress\(rw,all_squash,anonuid=$uid,anongid=$gid\)/) {
  109:     print "Error. /etc/exports already has this entry enabled.\n";
  110:     unlink('/tmp/lock_lcnfs');
  111:     exit 7;
  112: }
  113: open (OUT,">>/etc/exports");
  114: print OUT $entry;
  115: close OUT;
  116: 
  117: # Resynchronize /etc/exports file
  118: system('/usr/sbin/exportfs','-r');
  119: 
  120: # Add entry /etc/hosts.allow
  121: my $hostsallow=`/bin/cat /etc/hosts.allow`;
  122: my $entry="# $safeusername\nportmap: $safeipaddress\n";
  123: if ($hostsallow=~/\n\# $safeusername\s*\nportmap: $safeipaddress\n/) {
  124:     print "Error. /etc/hosts already has this entry enabled.\n";
  125:     unlink('/tmp/lock_lcnfs');
  126:     exit 6;
  127: }
  128: open (OUT,">>/etc/hosts.allow");
  129: print OUT $entry;
  130: close OUT;
  131: 
  132: &disable_root_capability;
  133: unlink('/tmp/lock_lcnfs');
  134: exit 0;
  135: 
  136: # ----------------------------------------------------------- have setuid script run as root
  137: sub enable_root_capability {
  138:     if ($wwwid==$>) {
  139: 	($<,$>)=($>,$<);
  140: 	($(,$))=($),$();
  141:     }
  142:     else {
  143: 	# root capability is already enabled
  144:     }
  145:     return $>;
  146: }
  147: 
  148: # ----------------------------------------------------------- have setuid script run as www
  149: sub disable_root_capability {
  150:     if ($wwwid==$<) {
  151: 	($<,$>)=($>,$<);
  152: 	($(,$))=($),$();
  153:     }
  154:     else {
  155: 	# root capability is already disabled
  156:     }
  157: }
  158: 
  159: # ----------------------------------- make sure that another lcnfs process isn't running
  160: sub try_to_lock {
  161:     my ($lockfile)=@_;
  162:     my $currentpid;
  163:     my $lastpid;
  164:     # Do not manipulate lock file as root
  165:     if ($>==0) {
  166: 	return 0;
  167:     }
  168:     # Try to generate lock file.
  169:     # Wait 3 seconds.  If same process id is in
  170:     # lock file, then assume lock file is stale, and
  171:     # go ahead.  If process id's fluctuate, try
  172:     # for a maximum of 10 times.
  173:     for (0..10) {
  174: 	if (-e $lockfile) {
  175: 	    open(LOCK,"<$lockfile");
  176: 	    $currentpid=<LOCK>;
  177: 	    close LOCK;
  178: 	    if ($currentpid==$lastpid) {
  179: 		last;
  180: 	    }
  181: 	    sleep 3;
  182: 	    $lastpid=$currentpid;
  183: 	}
  184: 	else {
  185: 	    last;
  186: 	}
  187: 	if ($_==10) {
  188: 	    return 0;
  189: 	}
  190:     }
  191:     open(LOCK,">$lockfile");
  192:     print LOCK $$;
  193:     close LOCK;
  194:     return 1;
  195: }