Setuid到Perl脚本

Question

我使用的是一个Perl脚本，它从sendmail的mqueue文件夹中删除数据。

当我通过setuid连接到该Perl脚本并试图从用户运行它时，它抛出以下消息：

Insecure dependency in chdir while running setuid at /file/find

如何解决这个问题，并以root权限成功运行脚本？

!/usr/bin/perl

use strict;

my $qtool = "/usr/local/bin/qtool.pl";
my $mqueue_directory = "/var/spool/mqueue";
my $messages_removed = 0;

use File::Find;
# Recursively find all files and directories in $mqueue_directory
find(\&wanted, $mqueue_directory);

sub wanted {
   # Is this a qf* file?
   if ( /^qf(\w{14})/ ) {
      my $qf_file = $_;
      my $queue_id = $1;
      my $deferred = 0;
      my $from_postmaster = 0;
      my $delivery_failure = 0;
      my $double_bounce = 0;
      open (QF_FILE, $_);
      while(<QF_FILE>) {
         $deferred = 1 if ( /^MDeferred/ );
         $from_postmaster = 1 if ( /^S<>$/ );
         $delivery_failure = 1 if \
            ( /^H\?\?Subject: DELIVERY FAILURE: (User|Recipient)/ );
         if ( $deferred && $from_postmaster && $delivery_failure ) {
            $double_bounce = 1;
            last;
         }
      }
      close (QF_FILE);
      if ($double_bounce) {
         print "Removing $queue_id...\n";
         system "$qtool", "-d", $qf_file;
         $messages_removed++;
      }
   }
}

print "\n$messages_removed total \"double bounce\" message(s) removed from ";
print "mail queue.\n";

Answer 1

“不安全的依赖”是一个Taint的东西：http://perldoc.perl.org/perlsec.html。

因为您已经运行了脚本setuid，所以正在强制执行污点。您需要将untaint指定为文件：：Find:的%Option键。

http://metacpan.org/pod/File::Find

my %options = (
    wanted => \&wanted,
    untaint => 1
);

find(\%options, $mqueue_directory);

您还应该查看File::Find的POD中的untaint_pattern。

Answer 2

您应该构建一个程序包装器。在几乎所有的unix系统上，脚本永远不能通过SetUID位获得根用户权限。你可以在这里找到一些有用的例子http://www.tuxation.com/setuid-on-shell-scripts.html