2 <!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
3 <?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
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23 <modulesynopsis metafile="mod_authn_dbd.xml.meta">
25 <name>mod_authn_dbd</name>
26 <description>User authentication using an SQL database</description>
27 <status>Extension</status>
28 <sourcefile>mod_authn_dbd.c</sourcefile>
29 <identifier>authn_dbd_module</identifier>
32 <p>This module provides authentication front-ends such as
33 <module>mod_auth_digest</module> and <module>mod_auth_basic</module>
34 to authenticate users by looking up users in SQL tables.
35 Similar functionality is provided by, for example,
36 <module>mod_authn_file</module>.</p>
37 <p>This module relies on <module>mod_dbd</module> to specify
38 the backend database driver and connection parameters, and
39 manage the database connections.</p>
41 <p>When using <module>mod_auth_basic</module> or
42 <module>mod_auth_digest</module>, this module is invoked via the
43 <directive module="mod_auth_basic">AuthBasicProvider</directive> or
44 <directive module="mod_auth_digest">AuthDigestProvider</directive>
45 with the <code>dbd</code> value.</p>
48 <seealso><directive module="mod_authn_core">AuthName</directive></seealso>
49 <seealso><directive module="mod_authn_core">AuthType</directive></seealso>
51 <directive module="mod_auth_basic">AuthBasicProvider</directive>
54 <directive module="mod_auth_digest">AuthDigestProvider</directive>
56 <seealso><directive module="mod_dbd">DBDriver</directive></seealso>
57 <seealso><directive module="mod_dbd">DBDParams</directive></seealso>
58 <seealso><a href="../misc/password_encryptions.html">Password Formats</a></seealso>
60 <section id="socache">
61 <title>Performance and Cacheing</title>
62 <p>Some users of DBD authentication in HTTPD 2.2/2.4 have reported that it
63 imposes a problematic load on the database. This is most likely where
64 an HTML page contains hundreds of objects (e.g. images, scripts, etc)
65 each of which requires authentication. Users affected (or concerned)
66 by this kind of problem should use <module>mod_authn_socache</module>
67 to cache credentials and take most of the load off the database.</p>
70 <section id="example">
71 <title>Configuration Example</title>
72 <p>This simple example shows use of this module in the context of
73 the Authentication and DBD frameworks.</p>
74 <highlight language="config">
75 # mod_dbd configuration
76 # UPDATED to include authentication cacheing
78 DBDParams "dbname=apacheauth user=apache password=xxxxxx"
85 <Directory /usr/www/myhost/private>
86 # mod_authn_core and mod_auth_basic configuration
91 # To cache credentials, put socache ahead of dbd here
92 AuthBasicProvider socache dbd
94 # Also required for caching: tell the cache to cache dbd lookups!
95 AuthnCacheProvideFor dbd
96 AuthnCacheContext my-server
98 # mod_authz_core configuration
101 # mod_authn_dbd SQL query to authenticate a user
102 AuthDBDUserPWQuery "SELECT password FROM authn WHERE user = %s"
107 <section id="exposed">
108 <title>Exposing Login Information</title>
110 If httpd was built against <glossary>APR</glossary> version 1.3.0
111 or higher, then whenever a query is made to the database server, all
112 column values in the first row returned by the query are placed in the
113 environment, using environment variables with the prefix "AUTHENTICATE_".
115 <p>If a database query for example returned the username, full name
116 and telephone number of a user, a CGI program will have access to
117 this information without the need to make a second independent database
118 query to gather this additional information.</p>
119 <p>This has the potential to dramatically simplify the coding and
120 configuration required in some web applications.
124 <section id="security">
125 <title>Preventing SQL injections</title>
126 <p>Whether you need to care about SQL security depends on what DBD driver
127 and backend you use. With most drivers you don't have to do anything :
128 the statement is prepared by the database at startup, and user input is
129 used only as data. But you may need to untaint your input. At the time
130 of writing, the only driver that requires you to take care is FreeTDS.</p>
131 <p>Please read <module>mod_dbd</module> documentation for more information
132 about security on this scope.</p>
136 <name>AuthDBDUserPWQuery</name>
137 <description>SQL query to look up a password for a user</description>
138 <syntax>AuthDBDUserPWQuery <var>query</var></syntax>
139 <contextlist><context>directory</context>
143 <p>The <directive>AuthDBDUserPWQuery</directive> specifies an
144 SQL query to look up a password for a specified user. The user's ID
145 will be passed as a single string parameter when the SQL query is
146 executed. It may be referenced within the query statement using
147 a <code>%s</code> format specifier.</p>
148 <highlight language="config">
149 AuthDBDUserPWQuery "SELECT password FROM authn WHERE user = %s"
151 <p>The first column value of the first row returned by the query
152 statement should be a string containing the encrypted password.
153 Subsequent rows will be ignored. If no rows are returned, the user
154 will not be authenticated through <module>mod_authn_dbd</module>.</p>
155 <p>If httpd was built against <glossary>APR</glossary> version 1.3.0
156 or higher, any additional column values in the first row returned by
157 the query statement will be stored as environment variables with
158 names of the form <code>AUTHENTICATE_<var>COLUMN</var></code>.
160 <p>The encrypted password format depends on which authentication
161 frontend (e.g. <module>mod_auth_basic</module> or
162 <module>mod_auth_digest</module>) is being used. See <a
163 href="../misc/password_encryptions.html">Password Formats</a> for
164 more information.</p>
169 <name>AuthDBDUserRealmQuery</name>
170 <description>SQL query to look up a password hash for a user and realm.
172 <syntax>AuthDBDUserRealmQuery <var>query</var></syntax>
173 <contextlist><context>directory</context>
177 <p>The <directive>AuthDBDUserRealmQuery</directive> specifies an
178 SQL query to look up a password for a specified user and realm in a
179 digest authentication process.
180 The user's ID and the realm, in that order, will be passed as string
181 parameters when the SQL query is executed. They may be referenced
182 within the query statement using <code>%s</code> format specifiers.</p>
183 <highlight language="config">
184 AuthDBDUserRealmQuery "SELECT password FROM authn WHERE user = %s AND realm = %s"
186 <p>The first column value of the first row returned by the query
187 statement should be a string containing the encrypted password.
188 Subsequent rows will be ignored. If no rows are returned, the user
189 will not be authenticated through <module>mod_authn_dbd</module>.</p>
190 <p>If httpd was built against <glossary>APR</glossary> version 1.3.0
191 or higher, any additional column values in the first row returned by
192 the query statement will be stored as environment variables with
193 names of the form <code>AUTHENTICATE_<var>COLUMN</var></code>.
195 <p>The encrypted password format depends on which authentication
196 frontend (e.g. <module>mod_auth_basic</module> or
197 <module>mod_auth_digest</module>) is being used. See <a
198 href="../misc/password_encryptions.html">Password Formats</a> for
199 more information.</p>