3 Catalyst::Manual::Tutorial::Authorization - Catalyst Tutorial Part 5: Authorization
9 This is B<Part 5 of 9> for the Catalyst tutorial.
11 L<Totorial Overview|Catalyst::Manual::Tutorial>
17 L<Introduction|Catalyst::Manual::Tutorial::Intro>
21 L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics>
25 L<Basic CRUD|Catalyst::Manual::Tutorial03_BasicCRUD>
29 L<Authentication|Catalyst::Manual::Tutorial::Authentication>
37 L<Debugging|Catalyst::Manual::Tutorial::Debugging>
41 L<Testing|Catalyst::Manual::Tutorial::Testing>
45 L<AdvancedCRUD|Catalyst::Manual::Tutorial::AdvancedCRUD>
49 L<Appendicies|Catalyst::Manual::Tutorial::Appendicies>
57 This part of the tutorial adds role-based authorization to the existing authentication implemented in Part 4. It provides simple examples of how to use roles in both TT templates and controller actions. The first half looks at manually configured authorization. The second half looks at how the ACL authorization plugin can simplify your code.
59 B<TIP>: Note that all of the code for this part of the tutorial can be pulled from the Catalyst Subversion repository in one step with the following command:
61 svn checkout http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/Tutorial@###
62 IMPORTANT: Does not work yet. Will be completed for final version.
66 =head1 BASIC AUTHORIZATION
68 In this section you learn how to manually configure authorization.
71 =head2 Update Plugins to Include Support Authorization
73 Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list:
85 Authentication::Store::DBIC
86 Authentication::Credential::Password
90 Session::Store::FastMmap
91 Session::State::Cookie
95 =head2 Add Config Information for Authorization
97 Edit C<myapp.yml> and update it to match (everything from the "authorization:" line down is new):
103 # Note this first definition would be the same as setting
104 # __PACKAGE__->config->{authentication}->{dbic}->{user_class} = 'MyAppDB::User'
105 # in lib/MyApp.pm (IOW, each hash key becomes a "name:" in the YAML file).
107 # This is the model object created by Catalyst::Model::DBIC from your
108 # schema (you created 'MyAppDB::User' but as the Catalyst startup
109 # debug messages show, it was loaded as 'MyApp::Model::MyAppDB::User').
110 # NOTE: Omit 'MyAppDB::Model' to avoid a component lookup issue in Catalyst 5.66
111 user_class: MyAppDB::User
112 # This is the name of the field in your 'users' table that contains the user's name
114 # This is the name of the field in your 'users' table that contains the password
115 password_field: password
116 # Other options can go here for hashed passwords
117 # Enabled hashed passwords
118 password_type: hashed
119 # Use the SHA-1 hashing algorithm
120 password_hash_type: SHA-1
123 # This is the model object created by Catalyst::Model::DBIC from your
124 # schema (you created 'MyAppDB::Role' but as the Catalyst startup
125 # debug messages show, it was loaded as 'MyApp::Model::MyAppDB::Role').
126 # NOTE: Omit 'MyAppDB::Model' to avoid a component lookup issue in Catalyst 5.66
127 role_class: MyAppDB::Role
128 # The name of the field in the 'roles' table that contains the role name
130 # The name of the accessor used to map a user to a role
131 # See the has_many() in MyAppDB/User.pm
132 role_rel: map_user_role
133 # The name of the field in the user_role table that references the user
134 user_role_user_field: user_id
137 =head2 Add Role-Specific Logic to the "Book List" Template
139 Open C<root/src/books/list.tt2> in your editor and add the following lines to the bottom of the file:
141 <p>Hello [% Catalyst.user.username %], you have the following roles:</p>
144 [% # Dump list of roles -%]
145 [% FOR role = Catalyst.user.roles %]<li>[% role %]</li>[% END %]
149 [% # Add some simple role-specific logic to template %]
150 [% # Use $c->check_user_roles() to check authz -%]
151 [% IF Catalyst.check_user_roles('user') %]
152 [% # Give normal users a link for 'logout' %]
153 <a href="[% Catalyst.uri_for('/logout') %]">Logout</a>
156 [% # Can also use $c->user->check_roles() to check authz -%]
157 [% IF Catalyst.check_user_roles('admin') %]
158 [% # Give admin users a link for 'create' %]
159 <a href="[% Catalyst.uri_for('form_create') %]">Create</a>
163 This code displays a different combination of links depending on the roles assigned to the user..
166 =head2 Limit C<Books::add> to C<admin> Users
168 C<IF> statements in TT templates simply control the output that is sent to the user's browser; it provides no real enforcement (if users know or guess the appropriate URLs, they are still perfectly free to hit any action within your application). We need to enhance the controller logic to wrap restricted actions with role validation logic.
170 For example, we might want to restrict the "formless create" action to admin-level users by editing C<lib/MyApp/Controller/Books.pm> and updating C<url_create> to match the following code:
174 Create a book with the supplied title, and rating
175 with manual authorization
179 sub url_create : Local {
180 # In addition to self & context, get the title, rating & author_id args
181 # from the URL. Note that Catalyst automatically puts extra information
182 # after the "/<controller_name>/<action_name/" into @_
183 my ($self, $c, $title, $rating, $author_id) = @_;
185 # Check the user's roles
186 if ($c->check_user_roles('admin')) {
187 # Call create() on the book model object. Pass the table
188 # columns/field values we want to set as hash values
189 my $book = $c->model('MyAppDB::Book')->create({
194 # Add a record to the join table for this book, mapping to
196 $book->add_to_book_authors({author_id => $author_id});
197 # Note: Above is a shortcut for this:
198 # $book->create_related('book_authors', {author_id => $author_id});
200 # Assign the Book object to the stash for display in the view
201 $c->stash->{book} = $book;
203 # This is a hack to disable XSUB processing in Data::Dumper
204 # (it's used in the view). This is a work-around for a bug in
205 # the interaction of some versions or Perl, Data::Dumper & DBIC.
206 # You won't need this if you aren't using Data::Dumper (or if
207 # you are running DBIC 0.06001 or greater), but adding it doesn't
208 # hurt anything either.
209 $Data::Dumper::Useperl = 1;
211 # Set the TT template to use
212 $c->stash->{template} = 'books/create_done.tt2';
214 # Provide very simple feedback to the user
215 $c->response->body('Unauthorized!');
220 To add authorization, we simply write the main code of this method in an C<if> statement that calls C<check_user_roles>. If the user does not have the appropriate permissions, they receive an "Unauthorized!" message. Note that we intentionally chose to display the message this way to demonstrate that TT templates will not be used if the response body has already been set. In reality you would probably want to use a technique that maintains the visual continuity of your template layout (for example, using the "status" or "error" message feature added in Part 2).
222 B<TIP>: If you want to keep your existing C<url_create> method, you can create a new copy and comment out the original by making it look like a Pod comment. For example, put something like C<=begin> before C<sub add : Local {> and C<=end> after the closing C<}>.
225 =head2 Try Out Authentication And Authorization
227 Press C<Ctrl-C> to kill the previous server instance (if it's still running) and restart it:
229 $ script/myapp_server.pl
231 Now trying going to L<http://localhost:3000/books/list> and you should be taken to the login page (you might have to C<Shift+Reload> your browser). Try logging in with both C<test01> and C<test02> (both use a password of C<mypass>) and notice how the roles information updates at the bottom of the "Book List" page. Also try the C<Logout> link on the book list page.
233 Now the "url_create" URL will work if you are already logged in as user C<test01>, but receive an authorization failure if you are logged in as C<test02>. Try:
235 http://localhost:3000/books/url_create/test/1/6
237 while logged in as each user. Use one of the 'Logout' links (or go to L<http://localhost:3000/logout> in you browser directly) when you are done.
241 =head1 ENABLE ACL-BASED AUTHORIZATION
243 This section takes a brief look at how the L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> can automate much of the work required to perform role-based authorization in a Catalyst application.
246 =head2 Add the C<Catalyst::Plugin::Authorization::ACL> Plugin
248 Open C<lib/MyApp.pm> in your editor and add the following plugin to the C<use Catalyst> statement:
252 Note that the remaining C<use Catalyst> plugins from earlier sections are not shown here, but they should still be included.
255 =head2 Add ACL Rules to the Application Class
257 Open C<lib/MyApp.pm> in your editor and add the following B<BELOW> the C<__PACKAGE__-E<gt>setup;> statement:
259 # Authorization::ACL Rules
260 __PACKAGE__->deny_access_unless(
261 "/books/form_create",
264 __PACKAGE__->deny_access_unless(
265 "/books/form_create_do",
268 __PACKAGE__->deny_access_unless(
273 Each of the three statements above comprises an ACL plugin "rule". The first two rules only allow admin-level users to create new books using the form (both the form itself and the data submission logic are protected). The third statement allows both users and admin to delete books. The C</books/url_create> action will continue to be protected by the "manually configured" authorization created earlier in this part of the tutorial.
275 The ACL plugin permits you to apply allow/deny logic in a variety of ways. The following provides a basic overview of the capabilities:
281 The ACL plugin only operates on the Catalyst "private namespace". You are using the private namespace when you use C<Local> actions. C<Path>, C<Regex>, and C<Global> allow you to specify actions where the path and the namespace differ -- the ACL plugin will not work in these cases.
285 Each rule is expressed in a separate C<__PACKAGE__-E<gt>deny_access_unless()> or C<__PACKAGE__-E<gt>allow_access_if()> line (there are several other methods that can be used for more complex policies, see the C<METHODS> portion of the L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> documentation for more details).
289 Each rule can contain multiple roles but only a single path.
293 The rules are tried in order (with the "most specific" rules tested first), and processing stops at the first "match" where an allow or deny is specified. Rules "fall through" if there is not a "match" (where a "match" means the user has the specified role). If a "match" is found, then processing stops there and the appropriate allow/deny action is taken.
297 If none of the rules match, then access is allowed.
301 The rules currently need to be specific in the application class C<lib\MyApp.pm> B<after> the C<__PACKAGE__-E<gt>setup;> line.
306 =head2 Add a Method to Handle Access Violations
308 By default, L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> throws an exception when authorization fails. This will take the user to the Catalyst debug screen, or a "Please come back later" message if you are not using the C<-Debug> flag. This step uses the C<access_denied> method in order to provide more appropriate feedback to the user.
310 Open C<lib/MyApp/Controller/Books.pm> in your editor and add the following method:
314 Handle Catalyst::Plugin::Authorization::ACL access denied exceptions
318 sub access_denied : Private {
321 # Set the error message
322 $c->stash->{error_msg} = 'Unauthorized!';
329 Then run the Catalyst development server script:
331 $ script/myapp_server.pl
333 Log in as C<test02>. Once at the book list, click the "Create" link to try the C<form_create> action. You should receive a red "Unauthorized!" error message at the top of the list. (Note that in reality you would probably want to place the "Create" link code in C<root/src/books/list.tt2> inside an C<IF> statement that only displays the list to admin-level users.) If you log in as C<test01> you should be able to view the C<form_create> form and add a new book.
335 When you are done, use one of the 'Logout' links (or go to the L<http://localhost:3000/logout> URL directly) when you are done.
341 Kennedy Clark, C<hkclark@gmail.com>
343 Please report any errors, issues or suggestions to the author.
345 Copyright 2006, Kennedy Clark. All rights reserved.
347 This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.