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a script to enable nfs mounting service for a given user and ip address (numeric)

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