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 5. 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|Catalyst::Manual::Tutorial::Intro>.
70 =head1 BASIC AUTHORIZATION
72 In this section you learn how to manually configure authorization.
75 =head2 Update Plugins to Include Support for Authorization
77 Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list:
79 __PACKAGE__->setup(qw/
90 Session::Store::FastMmap
91 Session::State::Cookie
95 =head2 Add Config Information for Authorization
97 Edit C<myapp.conf> and update it to match the following (the
98 C<role_relation> and C<role_field> definitions are new):
100 # rename this file to MyApp.yml and put a : in front of "name" if
101 # you want to use yaml like in old versions of Catalyst
108 # Note this first definition would be the same as setting
109 # __PACKAGE__->config->{authentication}->{realms}->{dbic}
110 # ->{credential} = 'Password' in lib/MyApp.pm
112 # Specify that we are going to do password-based auth
114 # This is the name of the field in the users table with the
115 # password stored in it
116 password_field password
117 # Switch to more secure hashed passwords
119 # Use the SHA-1 hashing algorithm
120 password_hash_type SHA-1
123 # Use DBIC to retrieve username, password & role information
125 # This is the model object created by Catalyst::Model::DBIC
126 # from your schema (you created 'MyApp::Schema::User' but as
127 # the Catalyst startup debug messages show, it was loaded as
128 # 'MyApp::Model::DB::Users').
129 # NOTE: Omit 'MyApp::Model' here just as you would when using
130 # '$c->model("DB::Users)'
132 # This is the name of a many_to_many relation in the users
133 # object that points to the roles for that user
135 # This is the name of field in the roles table that contains
136 # the role information
144 =head2 Add Role-Specific Logic to the "Book List" Template
146 Open C<root/src/books/list.tt2> in your editor and add the following
147 lines to the bottom of the file:
149 <p>Hello [% c.user.username %], you have the following roles:</p>
152 [% # Dump list of roles -%]
153 [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %]
157 [% # Add some simple role-specific logic to template %]
158 [% # Use $c->check_user_roles() to check authz -%]
159 [% IF c.check_user_roles('user') %]
160 [% # Give normal users a link for 'logout' %]
161 <a href="[% c.uri_for('/logout') %]">Logout</a>
164 [% # Can also use $c->user->check_roles() to check authz -%]
165 [% IF c.check_user_roles('admin') %]
166 [% # Give admin users a link for 'create' %]
167 <a href="[% c.uri_for('form_create') %]">Create</a>
171 This code displays a different combination of links depending on the
172 roles assigned to the user.
175 =head2 Limit C<Books::add> to C<admin> Users
177 C<IF> statements in TT templates simply control the output that is sent
178 to the user's browser; it provides no real enforcement (if users know or
179 guess the appropriate URLs, they are still perfectly free to hit any
180 action within your application). We need to enhance the controller
181 logic to wrap restricted actions with role-validation logic.
183 For example, we might want to restrict the "formless create" action to
184 admin-level users by editing C<lib/MyApp/Controller/Books.pm> and
185 updating C<url_create> to match the following code:
189 Create a book with the supplied title and rating,
190 with manual authorization
194 sub url_create : Local {
195 # In addition to self & context, get the title, rating & author_id args
196 # from the URL. Note that Catalyst automatically puts extra information
197 # after the "/<controller_name>/<action_name/" into @_
198 my ($self, $c, $title, $rating, $author_id) = @_;
200 # Check the user's roles
201 if ($c->check_user_roles('admin')) {
202 # Call create() on the book model object. Pass the table
203 # columns/field values we want to set as hash values
204 my $book = $c->model('DB::Books')->create({
209 # Add a record to the join table for this book, mapping to
211 $book->add_to_book_authors({author_id => $author_id});
212 # Note: Above is a shortcut for this:
213 # $book->create_related('book_authors', {author_id => $author_id});
215 # Assign the Book object to the stash for display in the view
216 $c->stash->{book} = $book;
218 # This is a hack to disable XSUB processing in Data::Dumper
219 # (it's used in the view). This is a work-around for a bug in
220 # the interaction of some versions or Perl, Data::Dumper & DBIC.
221 # You won't need this if you aren't using Data::Dumper (or if
222 # you are running DBIC 0.06001 or greater), but adding it doesn't
223 # hurt anything either.
224 $Data::Dumper::Useperl = 1;
226 # Set the TT template to use
227 $c->stash->{template} = 'books/create_done.tt2';
229 # Provide very simple feedback to the user
230 $c->response->body('Unauthorized!');
235 To add authorization, we simply wrap the main code of this method in an
236 C<if> statement that calls C<check_user_roles>. If the user does not
237 have the appropriate permissions, they receive an "Unauthorized!"
238 message. Note that we intentionally chose to display the message this
239 way to demonstrate that TT templates will not be used if the response
240 body has already been set. In reality you would probably want to use a
241 technique that maintains the visual continuity of your template layout
242 (for example, using the "status" or "error" message feature added in
245 B<TIP>: If you want to keep your existing C<url_create> method, you can
246 create a new copy and comment out the original by making it look like a
247 Pod comment. For example, put something like C<=begin> before C<sub add
248 : Local {> and C<=end> after the closing C<}>.
251 =head2 Try Out Authentication And Authorization
253 Press C<Ctrl-C> to kill the previous server instance (if it's still
254 running) and restart it:
256 $ script/myapp_server.pl
258 Now trying going to L<http://localhost:3000/books/list> and you should
259 be taken to the login page (you might have to C<Shift+Reload> or
260 C<Ctrl+Reload> your browser and/or click the "Logout" link on the book
261 list page). Try logging in with both C<test01> and C<test02> (both
262 use a password of C<mypass>) and notice how the roles information
263 updates at the bottom of the "Book List" page. Also try the C<Logout>
264 link on the book list page.
266 Now the "url_create" URL will work if you are already logged in as user
267 C<test01>, but receive an authorization failure if you are logged in as
270 http://localhost:3000/books/url_create/test/1/6
272 while logged in as each user. Use one of the 'Logout' links (or go to
273 L<http://localhost:3000/logout> in your browser directly) when you are
277 =head1 ENABLE ACL-BASED AUTHORIZATION
279 This section takes a brief look at how the
280 L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL>
281 plugin can automate much of the work required to perform role-based
282 authorization in a Catalyst application.
285 =head2 Add the C<Catalyst::Plugin::Authorization::ACL> Plugin
287 Open C<lib/MyApp.pm> in your editor and add the following plugin to the
288 C<__PACKAGE__-E<gt>setup> statement:
292 Note that the remaining C<use Catalyst> plugins from earlier sections
293 are not shown here, but they should still be included.
296 =head2 Add ACL Rules to the Application Class
298 Open C<lib/MyApp.pm> in your editor and add the following B<BELOW> the
299 C<__PACKAGE__-E<gt>setup> statement:
301 # Authorization::ACL Rules
302 __PACKAGE__->deny_access_unless(
303 "/books/form_create",
306 __PACKAGE__->deny_access_unless(
307 "/books/form_create_do",
310 __PACKAGE__->deny_access_unless(
315 Each of the three statements above comprises an ACL plugin "rule". The
316 first two rules only allow admin-level users to create new books using
317 the form (both the form itself and the data submission logic are
318 protected). The third statement allows both users and admins to delete
319 books. The C</books/url_create> action will continue to be protected by
320 the "manually configured" authorization created earlier in this part of
323 The ACL plugin permits you to apply allow/deny logic in a variety of
324 ways. The following provides a basic overview of the capabilities:
330 The ACL plugin only operates on the Catalyst "private namespace". You
331 are using the private namespace when you use C<Local> actions. C<Path>,
332 C<Regex>, and C<Global> allow you to specify actions where the path and
333 the namespace differ -- the ACL plugin will not work in these cases.
337 Each rule is expressed in a separate
338 C<__PACKAGE__-E<gt>deny_access_unless()> or
339 C<__PACKAGE__-E<gt>allow_access_if()> line (there are several other
340 methods that can be used for more complex policies, see the C<METHODS>
342 L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL>
343 documentation for more details).
347 Each rule can contain multiple roles but only a single path.
351 The rules are tried in order (with the "most specific" rules tested
352 first), and processing stops at the first "match" where an allow or deny
353 is specified. Rules "fall through" if there is not a "match" (where a
354 "match" means the user has the specified role). If a "match" is found,
355 then processing stops there and the appropriate allow/deny action is
360 If none of the rules match, then access is allowed.
364 The rules currently need to be specified in the application class
365 C<lib\MyApp.pm> B<after> the C<__PACKAGE__-E<gt>setup;> line.
370 =head2 Add a Method to Handle Access Violations
373 L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL>
374 throws an exception when authorization fails. This will take the user
375 to the Catalyst debug screen, or a "Please come back later" message if
376 you are not using the C<-Debug> flag. This step uses the
377 C<access_denied> method in order to provide more appropriate feedback to
380 Open C<lib/MyApp/Controller/Books.pm> in your editor and add the
385 Handle Catalyst::Plugin::Authorization::ACL access denied exceptions
389 sub access_denied : Private {
392 # Set the error message
393 $c->stash->{error_msg} = 'Unauthorized!';
399 Then run the Catalyst development server script:
401 $ script/myapp_server.pl
403 Log in as C<test02>. Once at the book list, click the "Create" link
404 to try the C<form_create> action. You should receive a red
405 "Unauthorized!" error message at the top of the list. (Note that in
406 the example code the "Create" link code in C<root/src/books/list.tt2>
407 is inside an C<IF> statement that only displays the list to
408 admin-level users.) If you log in as C<test01> you should be able to
409 view the C<form_create> form and add a new book.
411 When you are done, use one of the 'Logout' links (or go to the
412 L<http://localhost:3000/logout> URL directly) when you are done.
417 Kennedy Clark, C<hkclark@gmail.com>
419 Please report any errors, issues or suggestions to the author. The
420 most recent version of the Catalyst Tutorial can be found at
421 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>.
423 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
424 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).