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Apache HTTP Server Version 2.4
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Apache Module mod_authz_dbd
| Description: | Group Authorization and Login using SQL |
|---|---|
| Status: | Extension |
| Module Identifier: | authz_dbd_module |
| Source File: | mod_authz_dbd.c |
| Compatibility: | Available in Apache 2.4 and later |
Summary
This module provides authorization capabilities so that authenticated users can be allowed or denied access to portions of the web site by group membership. Similar functionality is provided by mod_authz_groupfile and mod_authz_dbm, with the exception that this module queries a SQL database to determine whether a user is a member of a group.
This module can also provide database-backed user login/logout capabilities. These are likely to be of most value when used in conjunction with mod_authn_dbd.
This module relies on mod_dbd to specify the backend database driver and connection parameters, and manage the database connections.
Topics
Directives
Bugfix checklist
See also
The Require Directives
Apache's Require directives are used during the authorization phase to ensure that a user is allowed to access a resource. mod_authz_dbd extends the authorization types with dbd-group, dbd-login and dbd-logout.
Since v2.4.8, expressions are supported within the DBD require directives.
Require dbd-group
Specify group membership that is required for the user to gain access.
Require dbd-group team AuthzDBDQuery "SELECT group FROM authz WHERE user = %s"
Require dbd-login
Specify a query to be run indicating the user has logged in.
Require dbd-login AuthzDBDQuery "UPDATE authn SET login = 'true' WHERE user = %s"
Require dbd-logout
Specify a query to be run indicating the user has logged out.
Require dbd-logout AuthzDBDQuery "UPDATE authn SET login = 'false' WHERE user = %s"
Database Login
In addition to the standard authorization function of checking group membership, this module can also provide server-side user session management via database-backed login/logout capabilities. Specifically, it can update a user's session status in the database whenever the user visits designated URLs (subject of course to users supplying the necessary credentials).
This works by defining two special Require types: Require dbd-login and Require dbd-logout. For usage details, see the configuration example below.
Client Login integration
Some administrators may wish to implement client-side session management that works in concert with the server-side login/logout capabilities offered by this module, for example, by setting or unsetting an HTTP cookie or other such token when a user logs in or out.
To support such integration, mod_authz_dbd exports an optional hook that will be run whenever a user's status is updated in the database. Other session management modules can then use the hook to implement functions that start and end client-side sessions.
Configuration example
# mod_dbd configuration
DBDriver pgsql
DBDParams "dbname=apacheauth user=apache pass=xxxxxx"
DBDMin 4
DBDKeep 8
DBDMax 20
DBDExptime 300
<Directory "/usr/www/my.site/team-private/">
# mod_authn_core and mod_auth_basic configuration
# for mod_authn_dbd
AuthType Basic
AuthName Team
AuthBasicProvider dbd
# mod_authn_dbd SQL query to authenticate a logged-in user
AuthDBDUserPWQuery \
"SELECT password FROM authn WHERE user = %s AND login = 'true'"
# mod_authz_core configuration for mod_authz_dbd
Require dbd-group team
# mod_authz_dbd configuration
AuthzDBDQuery "SELECT group FROM authz WHERE user = %s"
# when a user fails to be authenticated or authorized,
# invite them to login; this page should provide a link
# to /team-private/login.html
ErrorDocument 401 "/login-info.html"
<Files "login.html">
# don't require user to already be logged in!
AuthDBDUserPWQuery "SELECT password FROM authn WHERE user = %s"
# dbd-login action executes a statement to log user in
Require dbd-login
AuthzDBDQuery "UPDATE authn SET login = 'true' WHERE user = %s"
# return user to referring page (if any) after
# successful login
AuthzDBDLoginToReferer On
</Files>
<Files "logout.html">
# dbd-logout action executes a statement to log user out
Require dbd-logout
AuthzDBDQuery "UPDATE authn SET login = 'false' WHERE user = %s"
</Files>
</Directory>
AuthzDBDLoginToReferer Directive
| Description: | Determines whether to redirect the Client to the Referring page on successful login or logout if a Referer request header is present |
|---|---|
| Syntax: | AuthzDBDLoginToReferer On|Off |
| Default: | AuthzDBDLoginToReferer Off |
| Context: | directory |
| Status: | Extension |
| Module: | mod_authz_dbd |
In conjunction with Require dbd-login or Require dbd-logout, this provides the option to redirect the client back to the Referring page (the URL in the Referer HTTP request header, if present). When there is no Referer header, AuthzDBDLoginToReferer On will be ignored.
AuthzDBDQuery Directive
| Description: | Specify the SQL Query for the required operation |
|---|---|
| Syntax: | AuthzDBDQuery query |
| Context: | directory |
| Status: | Extension |
| Module: | mod_authz_dbd |
The AuthzDBDQuery specifies an SQL query to run. The purpose of the query depends on the Require directive in effect.
- When used with a Require dbd-group directive,
it specifies a query to look up groups for the current user. This is
the standard functionality of other authorization modules such as
mod_authz_groupfile and mod_authz_dbm.
The first column value of each row returned by the query statement
should be a string containing a group name. Zero, one, or more rows
may be returned.
Require dbd-group AuthzDBDQuery "SELECT group FROM groups WHERE user = %s"
- When used with a Require dbd-login or
Require dbd-logout directive, it will never deny access,
but will instead execute a SQL statement designed to log the user
in or out. The user must already be authenticated with
mod_authn_dbd.
Require dbd-login AuthzDBDQuery "UPDATE authn SET login = 'true' WHERE user = %s"
In all cases, the user's ID will be passed as a single string parameter when the SQL query is executed. It may be referenced within the query statement using a %s format specifier.
AuthzDBDRedirectQuery Directive
| Description: | Specify a query to look up a login page for the user |
|---|---|
| Syntax: | AuthzDBDRedirectQuery query |
| Context: | directory |
| Status: | Extension |
| Module: | mod_authz_dbd |
Specifies an optional SQL query to use after successful login (or logout) to redirect the user to a URL, which may be specific to the user. The user's ID will be passed as a single string parameter when the SQL query is executed. It may be referenced within the query statement using a %s format specifier.
AuthzDBDRedirectQuery "SELECT userpage FROM userpages WHERE user = %s"
The first column value of the first row returned by the query statement should be a string containing a URL to which to redirect the client. Subsequent rows will be ignored. If no rows are returned, the client will not be redirected.
Note that AuthzDBDLoginToReferer takes precedence if both are set.