3 Catalyst::Manual::Tutorial::Authorization - Catalyst Tutorial - Part 6: Authorization
8 This is B<Part 6 of 10> for the Catalyst tutorial.
10 L<Tutorial Overview|Catalyst::Manual::Tutorial>
16 L<Introduction|Catalyst::Manual::Tutorial::Intro>
20 L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics>
24 L<More Catalyst Basics|Catalyst::Manual::Tutorial::MoreCatalystBasics>
28 L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>
32 L<Authentication|Catalyst::Manual::Tutorial::Authentication>
40 L<Debugging|Catalyst::Manual::Tutorial::Debugging>
44 L<Testing|Catalyst::Manual::Tutorial::Testing>
48 L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD>
52 L<Appendices|Catalyst::Manual::Tutorial::Appendices>
59 This part of the tutorial adds role-based authorization to the existing
60 authentication implemented in Part 4. It provides simple examples of
61 how to use roles in both TT templates and controller actions. The first
62 half looks at manually configured authorization. The second half looks
63 at how the ACL authorization plugin can simplify your code.
65 You can checkout the source code for this example from the catalyst
66 subversion repository as per the instructions in
67 L<Catalyst::Manual::Tutorial::Intro>
69 =head1 BASIC AUTHORIZATION
71 In this section you learn how to manually configure authorization.
73 =head2 Update Plugins to Include Support for Authorization
75 Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list:
88 Session::Store::FastMmap
89 Session::State::Cookie
93 =head2 Add Config Information for Authorization
95 Edit C<myapp.conf> and update it to match the following (the
96 C<role_relation> and C<role_field> definitions are new):
104 # Note this first definition would be the same as setting
105 # __PACKAGE__->config->{authentication}->{realms}->{dbic}
106 # ->{credential} = 'Password' in lib/MyApp.pm
108 # Specify that we are going to do password-based auth
110 # This is the name of the field in the users table with the
111 # password stored in it
112 password_field password
113 # Switch to more secure hashed passwords
115 # Use the SHA-1 hashing algorithm
116 password_hash_type SHA-1
119 # Use DBIC to retrieve username, password & role information
121 # This is the model object created by Catalyst::Model::DBIC
122 # from your schema (you created 'MyApp::Schema::User' but as
123 # the Catalyst startup debug messages show, it was loaded as
124 # 'MyApp::Model::DB::Users').
125 # NOTE: Omit 'MyApp::Model' here just as you would when using
126 # '$c->model("DB::Users)'
128 # This is the name of the field in your 'users' table that
129 # contains the user's name
131 # This is the name of a many_to_many relation in the users
132 # object that points to the roles for that user
134 # This is the name of field in the roles table that contains
135 # the role information
143 =head2 Add Role-Specific Logic to the "Book List" Template
145 Open C<root/src/books/list.tt2> in your editor and add the following
146 lines to the bottom of the file:
148 <p>Hello [% Catalyst.user.username %], you have the following roles:</p>
151 [% # Dump list of roles -%]
152 [% FOR role = Catalyst.user.roles %]<li>[% role %]</li>[% END %]
156 [% # Add some simple role-specific logic to template %]
157 [% # Use $c->check_user_roles() to check authz -%]
158 [% IF Catalyst.check_user_roles('user') %]
159 [% # Give normal users a link for 'logout' %]
160 <a href="[% Catalyst.uri_for('/logout') %]">Logout</a>
163 [% # Can also use $c->user->check_roles() to check authz -%]
164 [% IF Catalyst.check_user_roles('admin') %]
165 [% # Give admin users a link for 'create' %]
166 <a href="[% Catalyst.uri_for('form_create') %]">Create</a>
170 This code displays a different combination of links depending on the
171 roles assigned to the user.
173 =head2 Limit C<Books::add> to C<admin> Users
175 C<IF> statements in TT templates simply control the output that is sent
176 to the user's browser; it provides no real enforcement (if users know or
177 guess the appropriate URLs, they are still perfectly free to hit any
178 action within your application). We need to enhance the controller
179 logic to wrap restricted actions with role-validation logic.
181 For example, we might want to restrict the "formless create" action to
182 admin-level users by editing C<lib/MyApp/Controller/Books.pm> and
183 updating C<url_create> to match the following code:
187 Create a book with the supplied title and rating,
188 with manual authorization
192 sub url_create : Local {
193 # In addition to self & context, get the title, rating & author_id args
194 # from the URL. Note that Catalyst automatically puts extra information
195 # after the "/<controller_name>/<action_name/" into @_
196 my ($self, $c, $title, $rating, $author_id) = @_;
198 # Check the user's roles
199 if ($c->check_user_roles('admin')) {
200 # Call create() on the book model object. Pass the table
201 # columns/field values we want to set as hash values
202 my $book = $c->model('DB::Books')->create({
207 # Add a record to the join table for this book, mapping to
209 $book->add_to_book_authors({author_id => $author_id});
210 # Note: Above is a shortcut for this:
211 # $book->create_related('book_authors', {author_id => $author_id});
213 # Assign the Book object to the stash for display in the view
214 $c->stash->{book} = $book;
216 # This is a hack to disable XSUB processing in Data::Dumper
217 # (it's used in the view). This is a work-around for a bug in
218 # the interaction of some versions or Perl, Data::Dumper & DBIC.
219 # You won't need this if you aren't using Data::Dumper (or if
220 # you are running DBIC 0.06001 or greater), but adding it doesn't
221 # hurt anything either.
222 $Data::Dumper::Useperl = 1;
224 # Set the TT template to use
225 $c->stash->{template} = 'books/create_done.tt2';
227 # Provide very simple feedback to the user
228 $c->response->body('Unauthorized!');
233 To add authorization, we simply wrap the main code of this method in an
234 C<if> statement that calls C<check_user_roles>. If the user does not
235 have the appropriate permissions, they receive an "Unauthorized!"
236 message. Note that we intentionally chose to display the message this
237 way to demonstrate that TT templates will not be used if the response
238 body has already been set. In reality you would probably want to use a
239 technique that maintains the visual continuity of your template layout
240 (for example, using the "status" or "error" message feature added in
243 B<TIP>: If you want to keep your existing C<url_create> method, you can
244 create a new copy and comment out the original by making it look like a
245 Pod comment. For example, put something like C<=begin> before C<sub add
246 : Local {> and C<=end> after the closing C<}>.
248 =head2 Try Out Authentication And Authorization
250 Press C<Ctrl-C> to kill the previous server instance (if it's still
251 running) and restart it:
253 $ script/myapp_server.pl
255 Now trying going to L<http://localhost:3000/books/list> and you should
256 be taken to the login page (you might have to C<Shift+Reload> your
257 browser and/or click the "Logout" link on the book list page). Try
258 logging in with both C<test01> and C<test02> (both use a password
259 of C<mypass>) and notice how the roles information updates at the
260 bottom of the "Book List" page. Also try the C<Logout> link on the
263 Now the "url_create" URL will work if you are already logged in as user
264 C<test01>, but receive an authorization failure if you are logged in as
267 http://localhost:3000/books/url_create/test/1/6
269 while logged in as each user. Use one of the 'Logout' links (or go to
270 L<http://localhost:3000/logout> in you browser directly) when you are
274 =head1 ENABLE ACL-BASED AUTHORIZATION
276 This section takes a brief look at how the
277 L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL>
278 plugin can automate much of the work required to perform role-based
279 authorization in a Catalyst application.
281 =head2 Add the C<Catalyst::Plugin::Authorization::ACL> Plugin
283 Open C<lib/MyApp.pm> in your editor and add the following plugin to the
284 C<use Catalyst> statement:
288 Note that the remaining C<use Catalyst> plugins from earlier sections
289 are not shown here, but they should still be included.
291 =head2 Add ACL Rules to the Application Class
293 Open C<lib/MyApp.pm> in your editor and add the following B<BELOW> the
294 C<__PACKAGE__-E<gt>setup;> statement:
296 # Authorization::ACL Rules
297 __PACKAGE__->deny_access_unless(
298 "/books/form_create",
301 __PACKAGE__->deny_access_unless(
302 "/books/form_create_do",
305 __PACKAGE__->deny_access_unless(
310 Each of the three statements above comprises an ACL plugin "rule". The
311 first two rules only allow admin-level users to create new books using
312 the form (both the form itself and the data submission logic are
313 protected). The third statement allows both users and admins to delete
314 books. The C</books/url_create> action will continue to be protected by
315 the "manually configured" authorization created earlier in this part of
318 The ACL plugin permits you to apply allow/deny logic in a variety of
319 ways. The following provides a basic overview of the capabilities:
325 The ACL plugin only operates on the Catalyst "private namespace". You
326 are using the private namespace when you use C<Local> actions. C<Path>,
327 C<Regex>, and C<Global> allow you to specify actions where the path and
328 the namespace differ -- the ACL plugin will not work in these cases.
332 Each rule is expressed in a separate
333 C<__PACKAGE__-E<gt>deny_access_unless()> or
334 C<__PACKAGE__-E<gt>allow_access_if()> line (there are several other
335 methods that can be used for more complex policies, see the C<METHODS>
337 L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL>
338 documentation for more details).
342 Each rule can contain multiple roles but only a single path.
346 The rules are tried in order (with the "most specific" rules tested
347 first), and processing stops at the first "match" where an allow or deny
348 is specified. Rules "fall through" if there is not a "match" (where a
349 "match" means the user has the specified role). If a "match" is found,
350 then processing stops there and the appropriate allow/deny action is
355 If none of the rules match, then access is allowed.
359 The rules currently need to be specific in the application class
360 C<lib\MyApp.pm> B<after> the C<__PACKAGE__-E<gt>setup;> line.
364 =head2 Add a Method to Handle Access Violations
367 L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL>
368 throws an exception when authorization fails. This will take the user
369 to the Catalyst debug screen, or a "Please come back later" message if
370 you are not using the C<-Debug> flag. This step uses the
371 C<access_denied> method in order to provide more appropriate feedback to
374 Open C<lib/MyApp/Controller/Books.pm> in your editor and add the
379 Handle Catalyst::Plugin::Authorization::ACL access denied exceptions
383 sub access_denied : Private {
386 # Set the error message
387 $c->stash->{error_msg} = 'Unauthorized!';
393 Then run the Catalyst development server script:
395 $ script/myapp_server.pl
397 Log in as C<test02>. Once at the book list, click the "Create" link
398 to try the C<form_create> action. You should receive a red
399 "Unauthorized!" error message at the top of the list. (Note that in
400 the example code the "Create" link code in C<root/src/books/list.tt2>
401 is inside an C<IF> statement that only displays the list to
402 admin-level users.) If you log in as C<test01> you should be able to
403 view the C<form_create> form and add a new book.
405 When you are done, use one of the 'Logout' links (or go to the
406 L<http://localhost:3000/logout> URL directly) when you are done.
411 Kennedy Clark, C<hkclark@gmail.com>
413 Please report any errors, issues or suggestions to the author. The
414 most recent version of the Catalyst Tutorial can be found at
415 L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Manual/lib/Catalyst/Manual/Tutorial/>.
417 Copyright 2006, Kennedy Clark, under Creative Commons License
418 (L<http://creativecommons.org/licenses/by-nc-sa/2.5/>).