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 provides Access Control List style path protection, with
arbitrary rules for Catalyst applications. It operates only on the
Catalyst private namespace, at least at the moment.
The two hierarchies of actions and controllers in Catalyst are:
Private Namespace
Every action has its 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 directly accessible from the outside, via a
URL.
The private and external paths will be the same, if you are using
Local actions. 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.
Various types of rules are supported, see the list under "RULES".
When a path is visited, rules are tested one after the other, with the
most exact rule fitting the path first, and continuing up the path.
Testing continues until a rule explcitly allows or denies access.
METHODS
allow_access_if
Arguments: $path, $rule
Check the rule condition and allow access to the actions under $path if
the rule returns 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 rule test returns false access is not denied or allowed. Instead
the next rule in the chain will be checked - in this sense the
combinatory behavior of these rules is like logical OR.
allow_access_if_any
Arguments: $path, \@roles
Same as above for any role in the list.
deny_access_unless
Arguments: $path, $rule
Check the rule condition and disallow access if the rule returns false.
This is normally useful to restrict access to any portion of the
application unless a certain condition can be met.
If the rule test returns true access is not allowed or denied. Instead
the next rule in the chain will be checked - in this sense the
combinatory behavior of these rules is like logical AND.
deny_access_unless_any
Arguments: $path, \@roles
Same as above for any role in the list.
allow_access
deny_access
Arguments: $path
Unconditionally allow or deny access to a path.
acl_add_rule
Arguments: $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).
acl_access_denied
Arguments: $c, $class, $action, $err
acl_access_allowed
Arguments: $c, $class, $action
The default event handlers for access denied or allowed conditions. See
below on handling access violations.
acl_allow_root_internals
Adds rules that permit access to the root controller (YourApp.pm)
"auto", "begin" and "end" unconditionally.
EXTENDED METHODS
execute
The hook for rule evaluation
setup_actions
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, access to the path 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
application, 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.
RULES
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_any( "/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_any" is used, the presence of any of the roles
in the list will immediately permit access, and if
"deny_access_unless_any" is used, the lack of all of the roles will
immediately deny access.
Similarly, 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 using "can" in UNIVERSAL.
Constant
You can use "undef", 0 and '' to use as a constant false predicate,
or 1 to use as a constant true predicate.
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 decides to explicitly allow or deny access, access will be
permitted.
Here is a rule that will always break out of rule processing 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;
}
}
);
HANDLING DENIAL
There are two plugin methods that can be called when a rule makes a
decision about an action:
acl_access_allowed
A no-op
acl_access_denied
Looks for a private action named "access_denied" from the denied
action's controller and outwards (much like "auto"), and if none is
found throws an access denied exception.
forcibly_allow_access
Within an "access_denied" action this will immediately cause the
blocked action to be executed anyway.
This means that you have several alternatives:
Provide an "access_denied" action
package MyApp::Controller::Foo;
sub access_denied : Private {
my ( $self, $c, $action ) = @_;
...
$c->forcibly_allow_access
if $you->mean_it eq "really";
}
If you call "forcibly_allow_access" then the blocked action will be
immediately unblocked. Otherwise the execution of the action will cease,
and return to it's caller or end.
Cleanup in "end"
sub end : Private {
my ( $self, $c ) = @_;
if ( $c->error and $c->error->[-1] eq "access denied" ) {
$c->error(0); # clear the error
# access denied
} else {
# normal end
}
}
Override the plugin event handler methods
package MyApp;
sub acl_access_allowed {
my ( $c, $class, $action ) = @_;
...
}
sub acl_access_denied {
my ( $c, $class, $action, $err ) = @_;
...
}
$class is the controller class the $action object was going to be
executed in, and $err is the exception cought during rule evaluation, if
any (access is denied if a rule raises an exception).
SEE ALSO
Catalyst::Plugin::Authentication,
Catalyst::Plugin::Authorization::Roles,
<http://catalyst.perl.org/calendar/2005/24>
AUTHOR
Yuval Kogman <nothingmuch@woobling.org>
CONTRIBUTORS
castaway: Jess Robinson
caelum: Rafael Kitover <rkitover@cpan.org>
COPYRIGHT & LICENSE
Copyright (c) 2008,2009 the aforementioned authors.
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.