NAME

Catalyst::Plugin::Authorization::ACL - ACL support for Catalyst applications.

SYNOPSIS

use Catalyst qw/
	Authentication
	Authorization::Roles
	Authorization::ACL
/;

__PACKAGE__->setup;

__PACKAGE__->deny_access_unless(
	"/foo/bar",
	[qw/nice_role/],
);

__PACKAGE__>allow_access_if(
	"/foo/bar/gorch",
	sub { return $boolean },
);

DESCRIPTION

This module provide Access Control Lists with arbitrary rules for Catalyst applications. It operates on the Catalyst private namespace, at least for the mean while.

The two hierarchies of actions and controllers in Catalyst are:

Private Namepsace

Every action has it's own private path. This path reflects the Perl namespaces the actions were born in, and the namespaces of their controllers.

External namespace

Some actions are also accessible from the outside, via another path.

This path is usually the same, if you used Local. Alternatively you can use Path, Regex, or Global to specify a different external path for your action.

The ACL module currently only knows to exploit the private namespace. In the future extensions may be made to support external namespaces as well.

METHODS

allow_access_if $path, $predicate

Check the predicate condition and allow access to the actions under $path if the predicate is true.

This is normally useful to allow acces only to a specific part of a tree whose parent has a deny_access_unless clause attached to it.

If the predicate condition is false access is not denied or allowed. Instead the next rule will be checked - in this sense the combinatory behavior of these rules is like logical OR.

deny_access_unless $path, $predicate

Check the predicate condition and disallow access if the predicacte is false.

This is normally useful to restrict access to any portion of the application unless a certain condition can be met.

If the predicate condition is true access is not allowed or denied. Instead the next rule will be checked - in this sense the combinatory behavior of these rules is like logical AND

acl_add_rule $path, $rule, [ $filter ]

Manually add a rule to all the actions under $path using the more flexible (but more verbose) method:

__PACKAGE__->acl_add_rule(
	"/foo",
	sub { ... }, # see FLEXIBLE RULES below
	sub {
		my $action = shift;
		# return a true value if you want to apply the rule to this action
		# called for all the actions under "/foo"
	}
};

In this case the rule must be a sub reference (or method name) to be invoked on $c.

The default filter will skip all actions starting with an underscore, namely _DISPATCH, _AUTO, etc (but not auto, begin, et al).

RULE EVALUATION

When a rule is attached to an action the "distance" from the path it was specified in is recorded. The closer the path is to the rule, the earlier it will be checked.

Any rule can either explicitly deny or explicitly allow access to a particular action. If a rule does not explicitly allow or permit access, the next rule is checked, until the list of rules is finished. If no rule has determined a policy, action to the controller will be permitted.

PATHS

To apply a rule to an action or group of actions you must supply a path.

This path is what you should see dumped at the begining of the Catalyst server's debug output.

For example, for the foo action defined at the root level of your applycation, specify /foo. Under the Moose controller (e.g. MyApp::C::Moose, the action bar will be /moose/bar).

The "distance" a path has from an action that is contained in it is the the difference in the number of slashes between the path of the action, and the path to which the rule was applied.

EASY RULES

There are several kinds of rules you can create without using the complex interface described in "FLEXIBLE RULES".

The easy rules are all predicate list oriented. allow_access_if will explicitly allow access if the predicate is true, and deny_access_unless will explicitly disallow if the predicate is false.

Role Lists

__PACAKGE__->deny_access_unless( "/foo/bar", [qw/admin moose_trainer/] );

When the role is evaluated the Catalyst::Plugin::Authorization::Roles will be used to check whether the currently logged in user has the specified roles.

If allow_access_if is used, the presence of all the roles will immediately permit access, and if deny_access_unless is used the lack of any of the roles will immediately deny access.

When specifying a role list without the Catalyst::Plugin::Authorization::Roles plugin loaded the ACL engine will throw an error.

Predicate Code Reference / Method Name

The code reference or method is invoked with the context and the action objects. The boolean return value will determine the behavior of the rule.

__PACKAGE__->allow_access_if( "/gorch", sub { ... } );
__PACKAGE__->deny_access_unless( "/moose", "method_name" );

When specifying a method name the rule engine ensures that it can be invoked uising "can" in UNIVERSAL.

FLEXIBLE RULES

These rules are the most annoying to write but provide the most flexibility.

All access control is performed using exceptions - $Catalyst::Plugin::Authorization::ACL::Engine::DENIED, and $Catalyst::Plugin::Authorization::ACL::Engine::ALLOWED (these can be imported from the engine module).

If no rule decided to explicitly allow or disallow access, access will be permitted.

Here is a rule that will always end the rule list by either explicitly allowing or denying access based on how much mojo the current user has:

__PACKAGE__->acl_add_rule(
	"/foo",
	sub {
		my ( $c, $action ) = @_;	
		
		if ( $c->user->mojo > 50 ) {
			die $ALLOWED;
		} else {
			die $DENIED;
		}
	}
);

SEE ALSO

Catalyst::Plugin::Authentication, Catalyst::Plugin::Authorization::Roles

AUTHOR

Yuval Kogman, nothingmuch@woobling.org

COPYRIGHT & LICNESE

Copyright (c) 2005 the aforementioned authors. All rights
reserved. This program is free software; you can redistribute
it and/or modify it under the same terms as Perl itself.