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1 | =head1 NAME |
2 | |
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3 | Catalyst::Manual::Tutorial::Authorization - Catalyst Tutorial - Part 6: Authorization |
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4 | |
5 | |
6 | =head1 OVERVIEW |
7 | |
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8 | This is B<Part 6 of 10> for the Catalyst tutorial. |
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9 | |
10 | L<Tutorial Overview|Catalyst::Manual::Tutorial> |
11 | |
12 | =over 4 |
13 | |
14 | =item 1 |
15 | |
16 | L<Introduction|Catalyst::Manual::Tutorial::Intro> |
17 | |
18 | =item 2 |
19 | |
20 | L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics> |
21 | |
22 | =item 3 |
23 | |
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24 | L<More Catalyst Basics|Catalyst::Manual::Tutorial::MoreCatalystBasics> |
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25 | |
26 | =item 4 |
27 | |
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28 | L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD> |
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29 | |
30 | =item 5 |
31 | |
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32 | L<Authentication|Catalyst::Manual::Tutorial::Authentication> |
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33 | |
34 | =item 6 |
35 | |
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36 | B<Authorization> |
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37 | |
38 | =item 7 |
39 | |
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40 | L<Debugging|Catalyst::Manual::Tutorial::Debugging> |
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41 | |
42 | =item 8 |
43 | |
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44 | L<Testing|Catalyst::Manual::Tutorial::Testing> |
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45 | |
46 | =item 9 |
47 | |
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48 | L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD> |
49 | |
50 | =item 10 |
51 | |
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52 | L<Appendices|Catalyst::Manual::Tutorial::Appendices> |
53 | |
54 | =back |
55 | |
56 | |
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57 | =head1 DESCRIPTION |
58 | |
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. |
64 | |
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> |
68 | |
69 | =head1 BASIC AUTHORIZATION |
70 | |
71 | In this section you learn how to manually configure authorization. |
72 | |
73 | =head2 Update Plugins to Include Support for Authorization |
74 | |
75 | Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list: |
76 | |
77 | use Catalyst qw/ |
78 | -Debug |
79 | ConfigLoader |
80 | Static::Simple |
81 | |
82 | StackTrace |
83 | |
84 | Authentication |
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85 | Authorization::Roles |
86 | |
87 | Session |
88 | Session::Store::FastMmap |
89 | Session::State::Cookie |
90 | /; |
91 | |
92 | |
93 | =head2 Add Config Information for Authorization |
94 | |
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95 | Edit C<myapp.yml> and update it to match the following (the |
96 | C<role_relation> and C<role_field> definitions are new): |
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97 | |
98 | --- |
99 | name: MyApp |
100 | authentication: |
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101 | default_realm: dbic |
102 | realms: |
103 | dbic: |
104 | credential: |
105 | # Note this first definition would be the same as setting |
106 | # __PACKAGE__->config->{authentication}->{realms}->{dbic} |
107 | # ->{credential} = 'Password' in lib/MyApp.pm |
108 | # (IOW, each hash key becomes a "name:" in the YAML file). |
109 | # |
110 | # Specify that we are going to do password-based auth |
111 | class: Password |
112 | # This is the name of the field in the users table with the |
113 | # password stored in it |
114 | password_field: password |
115 | # We are using an unencrypted password now |
116 | password_type: clear |
117 | store: |
118 | # Use DBIC to retrieve username, password & role information |
119 | class: DBIx::Class |
120 | # This is the model object created by Catalyst::Model::DBIC |
121 | # from your schema (you created 'MyAppDB::User' but as the |
122 | # Catalyst startup debug messages show, it was loaded as |
123 | # 'MyApp::Model::MyAppDB::Users'). |
124 | # NOTE: Omit 'MyApp::Model' here just as you would when using |
125 | # '$c->model("MyAppDB::Users)' |
126 | user_class: MyAppDB::Users |
127 | # This is the name of the field in your 'users' table that |
128 | # contains the user's name |
129 | id_field: username |
130 | # This is the name of a many_to_many relation in the users |
131 | # object that points to the roles for that user |
132 | role_relation: roles |
133 | # This is the name of field in the roles table that contains |
134 | # the role information |
135 | role_field: role |
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136 | |
137 | |
138 | =head2 Add Role-Specific Logic to the "Book List" Template |
139 | |
140 | Open C<root/src/books/list.tt2> in your editor and add the following |
141 | lines to the bottom of the file: |
142 | |
143 | <p>Hello [% Catalyst.user.username %], you have the following roles:</p> |
144 | |
145 | <ul> |
146 | [% # Dump list of roles -%] |
147 | [% FOR role = Catalyst.user.roles %]<li>[% role %]</li>[% END %] |
148 | </ul> |
149 | |
150 | <p> |
151 | [% # Add some simple role-specific logic to template %] |
152 | [% # Use $c->check_user_roles() to check authz -%] |
153 | [% IF Catalyst.check_user_roles('user') %] |
154 | [% # Give normal users a link for 'logout' %] |
155 | <a href="[% Catalyst.uri_for('/logout') %]">Logout</a> |
156 | [% END %] |
157 | |
158 | [% # Can also use $c->user->check_roles() to check authz -%] |
159 | [% IF Catalyst.check_user_roles('admin') %] |
160 | [% # Give admin users a link for 'create' %] |
161 | <a href="[% Catalyst.uri_for('form_create') %]">Create</a> |
162 | [% END %] |
163 | </p> |
164 | |
165 | This code displays a different combination of links depending on the |
166 | roles assigned to the user. |
167 | |
168 | =head2 Limit C<Books::add> to C<admin> Users |
169 | |
170 | C<IF> statements in TT templates simply control the output that is sent |
171 | to the user's browser; it provides no real enforcement (if users know or |
172 | guess the appropriate URLs, they are still perfectly free to hit any |
173 | action within your application). We need to enhance the controller |
174 | logic to wrap restricted actions with role-validation logic. |
175 | |
176 | For example, we might want to restrict the "formless create" action to |
177 | admin-level users by editing C<lib/MyApp/Controller/Books.pm> and |
178 | updating C<url_create> to match the following code: |
179 | |
180 | =head2 url_create |
181 | |
182 | Create a book with the supplied title and rating, |
183 | with manual authorization |
184 | |
185 | =cut |
186 | |
187 | sub url_create : Local { |
188 | # In addition to self & context, get the title, rating & author_id args |
189 | # from the URL. Note that Catalyst automatically puts extra information |
190 | # after the "/<controller_name>/<action_name/" into @_ |
191 | my ($self, $c, $title, $rating, $author_id) = @_; |
192 | |
193 | # Check the user's roles |
194 | if ($c->check_user_roles('admin')) { |
195 | # Call create() on the book model object. Pass the table |
196 | # columns/field values we want to set as hash values |
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197 | my $book = $c->model('MyAppDB::Books')->create({ |
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198 | title => $title, |
199 | rating => $rating |
200 | }); |
201 | |
202 | # Add a record to the join table for this book, mapping to |
203 | # appropriate author |
204 | $book->add_to_book_authors({author_id => $author_id}); |
205 | # Note: Above is a shortcut for this: |
206 | # $book->create_related('book_authors', {author_id => $author_id}); |
207 | |
208 | # Assign the Book object to the stash for display in the view |
209 | $c->stash->{book} = $book; |
210 | |
211 | # This is a hack to disable XSUB processing in Data::Dumper |
212 | # (it's used in the view). This is a work-around for a bug in |
213 | # the interaction of some versions or Perl, Data::Dumper & DBIC. |
214 | # You won't need this if you aren't using Data::Dumper (or if |
215 | # you are running DBIC 0.06001 or greater), but adding it doesn't |
216 | # hurt anything either. |
217 | $Data::Dumper::Useperl = 1; |
218 | |
219 | # Set the TT template to use |
220 | $c->stash->{template} = 'books/create_done.tt2'; |
221 | } else { |
222 | # Provide very simple feedback to the user |
223 | $c->response->body('Unauthorized!'); |
224 | } |
225 | } |
226 | |
227 | |
228 | To add authorization, we simply wrap the main code of this method in an |
229 | C<if> statement that calls C<check_user_roles>. If the user does not |
230 | have the appropriate permissions, they receive an "Unauthorized!" |
231 | message. Note that we intentionally chose to display the message this |
232 | way to demonstrate that TT templates will not be used if the response |
233 | body has already been set. In reality you would probably want to use a |
234 | technique that maintains the visual continuity of your template layout |
235 | (for example, using the "status" or "error" message feature added in |
236 | Part 2). |
237 | |
238 | B<TIP>: If you want to keep your existing C<url_create> method, you can |
239 | create a new copy and comment out the original by making it look like a |
240 | Pod comment. For example, put something like C<=begin> before C<sub add |
241 | : Local {> and C<=end> after the closing C<}>. |
242 | |
243 | =head2 Try Out Authentication And Authorization |
244 | |
245 | Press C<Ctrl-C> to kill the previous server instance (if it's still |
246 | running) and restart it: |
247 | |
248 | $ script/myapp_server.pl |
249 | |
250 | Now trying going to L<http://localhost:3000/books/list> and you should |
251 | be taken to the login page (you might have to C<Shift+Reload> your |
252 | browser and/or click the "Logout" link on the book list page). Try |
253 | logging in with both C<test01> and C<test02> (both use a password |
254 | of C<mypass>) and notice how the roles information updates at the |
255 | bottom of the "Book List" page. Also try the C<Logout> link on the |
256 | book list page. |
257 | |
258 | Now the "url_create" URL will work if you are already logged in as user |
259 | C<test01>, but receive an authorization failure if you are logged in as |
260 | C<test02>. Try: |
261 | |
262 | http://localhost:3000/books/url_create/test/1/6 |
263 | |
264 | while logged in as each user. Use one of the 'Logout' links (or go to |
265 | L<http://localhost:3000/logout> in you browser directly) when you are |
266 | done. |
267 | |
268 | |
269 | =head1 ENABLE ACL-BASED AUTHORIZATION |
270 | |
271 | This section takes a brief look at how the |
272 | L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> |
273 | plugin can automate much of the work required to perform role-based |
274 | authorization in a Catalyst application. |
275 | |
276 | =head2 Add the C<Catalyst::Plugin::Authorization::ACL> Plugin |
277 | |
278 | Open C<lib/MyApp.pm> in your editor and add the following plugin to the |
279 | C<use Catalyst> statement: |
280 | |
281 | Authorization::ACL |
282 | |
283 | Note that the remaining C<use Catalyst> plugins from earlier sections |
284 | are not shown here, but they should still be included. |
285 | |
286 | =head2 Add ACL Rules to the Application Class |
287 | |
288 | Open C<lib/MyApp.pm> in your editor and add the following B<BELOW> the |
289 | C<__PACKAGE__-E<gt>setup;> statement: |
290 | |
291 | # Authorization::ACL Rules |
292 | __PACKAGE__->deny_access_unless( |
293 | "/books/form_create", |
294 | [qw/admin/], |
295 | ); |
296 | __PACKAGE__->deny_access_unless( |
297 | "/books/form_create_do", |
298 | [qw/admin/], |
299 | ); |
300 | __PACKAGE__->deny_access_unless( |
301 | "/books/delete", |
302 | [qw/user admin/], |
303 | ); |
304 | |
305 | Each of the three statements above comprises an ACL plugin "rule". The |
306 | first two rules only allow admin-level users to create new books using |
307 | the form (both the form itself and the data submission logic are |
308 | protected). The third statement allows both users and admins to delete |
309 | books. The C</books/url_create> action will continue to be protected by |
310 | the "manually configured" authorization created earlier in this part of |
311 | the tutorial. |
312 | |
313 | The ACL plugin permits you to apply allow/deny logic in a variety of |
314 | ways. The following provides a basic overview of the capabilities: |
315 | |
316 | =over 4 |
317 | |
318 | =item * |
319 | |
320 | The ACL plugin only operates on the Catalyst "private namespace". You |
321 | are using the private namespace when you use C<Local> actions. C<Path>, |
322 | C<Regex>, and C<Global> allow you to specify actions where the path and |
323 | the namespace differ -- the ACL plugin will not work in these cases. |
324 | |
325 | =item * |
326 | |
327 | Each rule is expressed in a separate |
328 | C<__PACKAGE__-E<gt>deny_access_unless()> or |
329 | C<__PACKAGE__-E<gt>allow_access_if()> line (there are several other |
330 | methods that can be used for more complex policies, see the C<METHODS> |
331 | portion of the |
332 | L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> |
333 | documentation for more details). |
334 | |
335 | =item * |
336 | |
337 | Each rule can contain multiple roles but only a single path. |
338 | |
339 | =item * |
340 | |
341 | The rules are tried in order (with the "most specific" rules tested |
342 | first), and processing stops at the first "match" where an allow or deny |
343 | is specified. Rules "fall through" if there is not a "match" (where a |
344 | "match" means the user has the specified role). If a "match" is found, |
345 | then processing stops there and the appropriate allow/deny action is |
346 | taken. |
347 | |
348 | =item * |
349 | |
350 | If none of the rules match, then access is allowed. |
351 | |
352 | =item * |
353 | |
354 | The rules currently need to be specific in the application class |
355 | C<lib\MyApp.pm> B<after> the C<__PACKAGE__-E<gt>setup;> line. |
356 | |
357 | =back |
358 | |
359 | =head2 Add a Method to Handle Access Violations |
360 | |
361 | By default, |
362 | L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> |
363 | throws an exception when authorization fails. This will take the user |
364 | to the Catalyst debug screen, or a "Please come back later" message if |
365 | you are not using the C<-Debug> flag. This step uses the |
366 | C<access_denied> method in order to provide more appropriate feedback to |
367 | the user. |
368 | |
369 | Open C<lib/MyApp/Controller/Books.pm> in your editor and add the |
370 | following method: |
371 | |
372 | =head2 access_denied |
373 | |
374 | Handle Catalyst::Plugin::Authorization::ACL access denied exceptions |
375 | |
376 | =cut |
377 | |
378 | sub access_denied : Private { |
379 | my ($self, $c) = @_; |
380 | |
381 | # Set the error message |
382 | $c->stash->{error_msg} = 'Unauthorized!'; |
383 | |
384 | # Display the list |
385 | $c->forward('list'); |
386 | } |
387 | |
388 | Then run the Catalyst development server script: |
389 | |
390 | $ script/myapp_server.pl |
391 | |
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392 | Log in as C<test02>. Once at the book list, click the "Create" link |
393 | to try the C<form_create> action. You should receive a red |
394 | "Unauthorized!" error message at the top of the list. (Note that in |
395 | the example code the "Create" link code in C<root/src/books/list.tt2> |
396 | is inside an C<IF> statement that only displays the list to |
397 | admin-level users.) If you log in as C<test01> you should be able to |
398 | view the C<form_create> form and add a new book. |
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399 | |
400 | When you are done, use one of the 'Logout' links (or go to the |
401 | L<http://localhost:3000/logout> URL directly) when you are done. |
402 | |
403 | |
404 | =head1 AUTHOR |
405 | |
406 | Kennedy Clark, C<hkclark@gmail.com> |
407 | |
408 | Please report any errors, issues or suggestions to the author. The |
409 | most recent version of the Catalyst Tutorial can be found at |
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410 | L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Manual/lib/Catalyst/Manual/Tutorial/>. |
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411 | |
412 | Copyright 2006, Kennedy Clark, under Creative Commons License |
413 | (L<http://creativecommons.org/licenses/by-nc-sa/2.5/>). |
414 | |