NAME¶
Safe::Hole - make a hole to the original main compartment in the Safe
compartment
SYNOPSIS¶
use Safe;
use Safe::Hole;
$cpt = new Safe;
$hole = new Safe::Hole {};
sub test { Test->test; }
$Testobj = new Test;
# $cpt->share('&test'); # alternate as next line
$hole->wrap(\&test, $cpt, '&test');
# ${$cpt->varglob('Testobj')} = $Testobj; # alternate as next line
$hole->wrap($Testobj, $cpt, '$Testobj');
$cpt->reval('test; $Testobj->test;');
print $@ if $@;
package Test;
sub new { bless {},shift(); }
sub test { my $self = shift; $self->test2; }
sub test2 { print "Test->test2 called\n"; }
DESCRIPTION¶
We can call outside defined subroutines from the Safe compartment
using share(), or can call methods through the object that is copied
into the Safe compartment using varglob(). But that subroutines or
methods are executed in the Safe compartment too, so they cannot call
another subroutines that are dinamically qualified with the package
name such as class methods nor can they compile code that uses opcodes
that are forbidden within the compartment.
Through Safe::Hole, we can execute outside defined subroutines in the
original main compartment from the Safe compartment.
Note that if a subroutine called through Safe::Hole::call does a
Carp::croak() it will report the error as having occured within
Safe::Hole. This can be avoided by including Safe::Hole::User in the
@ISA for the package containing the subroutine.
Methods¶
- new [NAMESPACE]
- Class method. Backward compatible constructor.
NAMESPACE is the alternate root namespace that makes the compartment in
which call() method execute the subroutine. Default of NAMESPACE
means the current 'main'. This emulates the behaviour of Safe-Hole-0.08
and earlier.
- new \%arguments
- Class method. Constructor.
The constructor is called with a hash reference providing the constructor
arguments. The argument ROOT specifies the alternate root namespace for
the object. If the ROOT argument is not specified then Safe::Hole object
will attempt restore as much as it can of the environment in which it was
constrtucted. This includes the opcode mask, %INC and @INC. If a root
namespace is specified then it would not make sense to restore the %INC
and @INC from main:: so this is not done. Also if a root namespace is
given the opcode mask is not restored either.
- call $coderef [,@args]
- Object method.
Call the subroutine refered by $coderef in the compartment that is
specified with constructor new. @args are passed as the arguments to the
called $coderef. Note that the arguments are not currently passed by
reference although this may change in a future version.
- wrap $ref [,$cpt ,$name]
- Object method.
If $ref is a code reference, this method returns the anonymous subroutine
reference that calls $ref using call() method of Safe::Hole (see
above).
If $ref is a class object, this method makes a wrapper class of that object
and returns a new object of the wrapper class. Through the wrapper class,
all original class methods called using call() method of
Safe::Hole.
If $cpt as Safe object and $name as subroutine or scalar name specified,
this method works like share() method of Safe. When $ref is a code
reference $name must like '&subroutine'. When $ref is a object $name
must like '$var'.
Name $name may not be same as referent of $ref. For example:
$hole->wrap(\&foo, $cpt, '&bar');
$hole->wrap(sub{...}, $cpt, '&foo');
$hole->wrap($objfoo, $cpt, '$objbar');
- root
- Object method. Return the namespace that is specified with constructor
new(). If no namespace was then root() returns 'main'.
Warning¶
You MUST NOT share the Safe::Hole object with the Safe compartment. If you do it
the Safe compartment is NOT safe.
This module provides a means to go from a state where an opcode is denied back
to a state where it is not. Reasonable care has been taken to ensure that
programs cannot simply manipulate the internals to the Safe::Hole object to
reduce the opmask in effect. However there may still be a way that the authors
have not considered. In particular it relies on the fact that a Perl program
cannot change stuff inside the magic on a Perl variable. If you install a
module that allows a Perl program to fiddle inside the magic then this
assuption breaks down. One would hope that any system that was running
un-trusted code would not have such a module installed.
AUTHORS¶
Sey Nakajima <nakajima@netstock.co.jp> (Initial version)
Brian McCauley <nobull@cpan.org> (Maintenance)
Todd Rinaldo <toddr@cpan.org> (Maintenance)
SEE ALSO¶
Safe(3).