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[apache] / docs / manual / mod / mod_authz_core.xml

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<modulesynopsis metafile="mod_authz_core.xml.meta">

<name>mod_authz_core</name>
<description>Core Authorization</description>
<status>Base</status>
<sourcefile>mod_authz_core.c</sourcefile>
<identifier>authz_core_module</identifier>
<compatibility>Available in Apache HTTPD 2.3 and later</compatibility>

<summary>
    <p>This module provides core authorization capabilities so that
    authenticated users can be allowed or denied access to portions
    of the web site. <module>mod_authz_core</module> provides the
    functionality to register various authorization providers. It is
    usually used in conjunction with an authentication
    provider module such as <module>mod_authn_file</module> and an
    authorization module such as <module>mod_authz_user</module>. It
    also allows for advanced logic to be applied to the
    authorization processing.</p>
</summary>

<section id="logic"><title>Authorization Containers</title>

    <p>The authorization container directives
    <directive module="mod_authz_core" type="section">RequireAll</directive>,
    <directive module="mod_authz_core" type="section">RequireAny</directive>
    and
    <directive module="mod_authz_core" type="section">RequireNone</directive>
    may be combined with each other and with the
    <directive module="mod_authz_core">Require</directive>
    directive to express complex authorization logic.</p>

    <p>The example below expresses the following authorization logic.
    In order to access the resource, the user must either be the
    <code>superadmin</code> user, or belong to both the
    <code>admins</code> group and the <code>Administrators</code> LDAP
    group and either belong to the <code>sales</code> group or
    have the LDAP <code>dept</code> attribute <code>sales</code>.
    Furthermore, in order to access the resource, the user must
    not belong to either the <code>temps</code> group or the
    LDAP group <code>Temporary Employees</code>.</p>

    <highlight language="config">
&lt;Directory /www/mydocs&gt;
    &lt;RequireAll&gt;
        &lt;RequireAny&gt;
            Require user superadmin
            &lt;RequireAll&gt;
                Require group admins
                Require ldap-group cn=Administrators,o=Airius
                &lt;RequireAny&gt;
                    Require group sales
                    Require ldap-attribute dept="sales"
                &lt;/RequireAny&gt;
            &lt;/RequireAll&gt;
        &lt;/RequireAny&gt;
        &lt;RequireNone&gt;
            Require group temps
            Require ldap-group cn=Temporary Employees,o=Airius
        &lt;/RequireNone&gt;
    &lt;/RequireAll&gt;
&lt;/Directory&gt;
    </highlight>
</section>

<section id="requiredirectives"><title>The Require Directives</title>

  <p><module>mod_authz_core</module> provides some generic authorization
  providers which can be used with the
  <directive module="mod_authz_core">Require</directive> directive.</p>

  <section id="reqenv"><title>Require env</title>

    <p>The <code>env</code> provider allows access to the server
    to be controlled based on the existence of an <a
    href="../env.html">environment variable</a>. When <code>Require
    env <var>env-variable</var></code> is specified, then the request is
    allowed access if the environment variable <var>env-variable</var>
    exists. The server provides the ability to set environment
    variables in a flexible way based on characteristics of the client
    request using the directives provided by
    <module>mod_setenvif</module>. Therefore, this directive can be
    used to allow access based on such factors as the clients
    <code>User-Agent</code> (browser type), <code>Referer</code>, or
    other HTTP request header fields.</p>

    <highlight language="config">
SetEnvIf User-Agent ^KnockKnock/2\.0 let_me_in
&lt;Directory /docroot&gt;
    Require env let_me_in
&lt;/Directory&gt;
    </highlight>

    <p>In this case, browsers with a user-agent string beginning
    with <code>KnockKnock/2.0</code> will be allowed access, and all
    others will be denied.</p>

  </section>

  <section id="reqall"><title>Require all</title>

    <p>The <code>all</code> provider mimics the functionality the
    was previously provided by the 'Allow from all' and 'Deny from all'
    directives.  This provider can take one of two arguments which are
    'granted' or 'denied'.  The following examples will grant or deny
    access to all requests.</p>

    <highlight language="config">
    Require all granted
    </highlight>

    <highlight language="config">
    Require all denied
    </highlight>

  </section>

  <section id="reqmethod"><title>Require method</title>

    <p>The <code>method</code> provider allows to use the HTTP method in
    authorization decisions. The GET and HEAD methods are treated as
    equivalent. The TRACE method is not available to this provider,
    use <directive module="core">TraceEnable</directive> instead.</p>

    <p>The following example will only allow GET, HEAD, POST, and OPTIONS
    requests:</p>

    <highlight language="config">
        Require method GET POST OPTIONS
    </highlight>

    <p>The following example will allow GET, HEAD, POST, and OPTIONS
    requests without authentication, and require a valid user for all other
    methods:</p>

    <highlight language="config">
&lt;RequireAny&gt;
    &nbsp;Require method GET POST OPTIONS
    &nbsp;Require valid-user
&lt;/RequireAny&gt;
    </highlight>

  </section>

  <section id="reqexpr"><title>Require expr</title>

  <p>The <code>expr</code> provider allows to base authorization
  decisions on arbitrary expressions.</p>

    <highlight language="config">
        Require expr "%{TIME_HOUR} -ge 9 &amp;&amp; %{TIME_HOUR} -le 17"
    </highlight>

  <p>The syntax is described in the <a href="../expr.html">ap_expr</a>
  documentation.</p>

  <p>Normally, the expression is evaluated before authentication. However, if
  the expression returns false and references the variable
  <code>%{REMOTE_USER}</code>, authentication will be performed and
  the expression will be re-evaluated.</p>

  </section>


</section>



<section id="authzalias"><title>Creating Authorization Provider Aliases</title>

    <p>Extended authorization providers can be created within the configuration
    file and assigned an alias name.  The alias providers can then be referenced
    through the <directive module="mod_authz_core">Require</directive> directive
    in the same way as a base authorization provider.  Besides the ability to
    create and alias an extended provider, it also allows the same extended
    authorization provider to be reference by multiple locations.
    </p>

    <section id="example"><title>Example</title>
        <p>The example below creates two different ldap authorization provider
        aliases based on the ldap-group authorization provider.  This example
        allows a single authorization location to check group membership within
        multiple ldap hosts:
        </p>

        <highlight language="config">
&lt;AuthzProviderAlias ldap-group ldap-group-alias1 cn=my-group,o=ctx&gt;
    AuthLDAPBindDN cn=youruser,o=ctx
    AuthLDAPBindPassword yourpassword
    AuthLDAPURL ldap://ldap.host/o=ctx
&lt;/AuthzProviderAlias&gt;

&lt;AuthzProviderAlias ldap-group ldap-group-alias2 cn=my-other-group,o=dev&gt;
    AuthLDAPBindDN cn=yourotheruser,o=dev
    AuthLDAPBindPassword yourotherpassword
    AuthLDAPURL ldap://other.ldap.host/o=dev?cn
&lt;/AuthzProviderAlias&gt;

Alias /secure /webpages/secure
&lt;Directory /webpages/secure&gt;
    Require all granted

    AuthBasicProvider file

    AuthType Basic
    AuthName LDAP_Protected_Place

    #implied OR operation
    Require ldap-group-alias1
    Require ldap-group-alias2
&lt;/Directory&gt;
        </highlight>
    </section>

</section>




<directivesynopsis>
<name>Require</name>
<description>Tests whether an authenticated user is authorized by
an authorization provider.</description>
<syntax>Require [not] <var>entity-name</var>
    [<var>entity-name</var>] ...</syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>This directive tests whether an authenticated user is authorized
    according to a particular authorization provider and the specified
    restrictions. <module>mod_authz_core</module> provides the following
    generic authorization providers:</p>

    <dl>
      <dt><code>Require all granted</code></dt>
      <dd>Access is allowed unconditionally.</dd>

      <dt><code>Require all denied</code></dt>
      <dd>Access is denied unconditionally.</dd>

      <dt><code>Require env <var>env-var</var> [<var>env-var</var>]
      ...</code></dt>
      <dd>Access is allowed only if one of the given environment variables is
          set.</dd>

      <dt><code>Require method <var>http-method</var> [<var>http-method</var>]
      ...</code></dt>
      <dd>Access is allowed only for the given HTTP methods.</dd>

      <dt><code>Require expr <var>expression</var> </code></dt>
      <dd>Access is allowed if <var>expression</var> evaluates to true.</dd>
    </dl>

    <p>Some of the allowed syntaxes provided by <module>mod_authz_user</module>,
       <module>mod_authz_host</module>,
       and <module>mod_authz_groupfile</module> are:</p>

    <dl>
      <dt><code>Require user <var>userid</var> [<var>userid</var>]
      ...</code></dt>
      <dd>Only the named users can access the resource.</dd>

      <dt><code>Require group <var>group-name</var> [<var>group-name</var>]
      ...</code></dt>
      <dd>Only users in the named groups can access the resource.</dd>

      <dt><code>Require valid-user</code></dt>
      <dd>All valid users can access the resource.</dd>

      <dt><code>Require ip 10 172.20 192.168.2</code></dt>
      <dd>Clients in the specified IP address ranges can access the
      resource.</dd>
    </dl>

    <p>Other authorization modules that implement require options
    include <module>mod_authnz_ldap</module>,
    <module>mod_authz_dbm</module>, <module>mod_authz_dbd</module>,
    <module>mod_authz_owner</module> and <module>mod_ssl</module>.</p>

    <p>In most cases, for a complete authentication and authorization
    configuration, <directive>Require</directive> must be accompanied by
    <directive module="mod_authn_core">AuthName</directive>, <directive
    module="mod_authn_core">AuthType</directive> and
    <directive module="mod_auth_basic">AuthBasicProvider</directive> or
    <directive module="mod_auth_digest">AuthDigestProvider</directive>
    directives, and directives such as
    <directive module="mod_authn_file">AuthUserFile</directive>
    and <directive module="mod_authz_groupfile">AuthGroupFile</directive> (to
    define users and groups) in order to work correctly. Example:</p>

    <highlight language="config">
AuthType Basic
AuthName "Restricted Resource"
AuthBasicProvider file
AuthUserFile /web/users
AuthGroupFile /web/groups
Require group admin
    </highlight>

    <p>Access controls which are applied in this way are effective for
    <strong>all</strong> methods. <strong>This is what is normally
    desired.</strong> If you wish to apply access controls only to
    specific methods, while leaving other methods unprotected, then
    place the <directive>Require</directive> statement into a
    <directive module="core" type="section">Limit</directive>
    section.</p>

    <p>The result of the <directive>Require</directive> directive
    may be negated through the use of the
    <code>not</code> option.  As with the other negated authorization
    directive <directive type="section">RequireNone</directive>,
    when the <directive>Require</directive> directive is negated it can
    only fail or return a neutral result, and therefore may never
    independently authorize a request.</p>

    <p>In the following example, all users in the <code>alpha</code>
    and <code>beta</code> groups are authorized, except for those who
    are also in the <code>reject</code> group.</p>

    <highlight language="config">
&lt;Directory /www/docs&gt;
    &lt;RequireAll&gt;
        Require group alpha beta
        Require not group reject
    &lt;/RequireAll&gt;
&lt;/Directory&gt;
    </highlight>

    <p>When multiple <directive>Require</directive> directives are
    used in a single
    <a href="../sections.html#merging">configuration section</a>
    and are not contained in another authorization directive like
    <directive module="mod_authz_core" type="section">RequireAll</directive>,
    they are implicitly contained within a
    <directive module="mod_authz_core" type="section">RequireAny</directive>
    directive.  Thus the first one to authorize a user authorizes the
    entire request, and subsequent <directive>Require</directive> directives
    are ignored.</p>

    <note type="warning"><title>Security Warning</title>
    <p>Exercise caution when setting authorization directives in
    <directive module="core">Location</directive> sections
    that overlap with content served out of the filesystem.
    By default, these <a href="../sections.html#merging"
    >configuration sections</a> overwrite authorization configuration
    in <directive module="core">Directory</directive>,
    and <directive module="core">Files</directive> sections.</p>
    <p>The <directive module="mod_authz_core">AuthMerging</directive> directive
    can be used to control how authorization configuration sections are
    merged.</p>
    </note>
</usage>

<seealso><a href="../howto/access.html">Access Control howto</a></seealso>
<seealso><a href="#logic">Authorization Containers</a></seealso>
<seealso><module>mod_authn_core</module></seealso>
<seealso><module>mod_authz_host</module></seealso>
</directivesynopsis>

<directivesynopsis type="section">
<name>RequireAll</name>
<description>Enclose a group of authorization directives of which none
must fail and at least one must succeed for the enclosing directive to
succeed.</description>
<syntax>&lt;RequireAll&gt; ... &lt;/RequireAll&gt;</syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p><directive type="section">RequireAll</directive> and
    <code>&lt;/RequireAll&gt;</code> are used to enclose a group of
    authorization directives of which none must fail and at least one
    must succeed in order for
    the <directive type="section">RequireAll</directive> directive to
    succeed.</p>

    <p>If none of the directives contained within the
    <directive type="section">RequireAll</directive> directive fails,
    and at least one succeeds, then the
    <directive type="section">RequireAll</directive> directive
    succeeds.  If none succeed and none fail, then it returns a
    neutral result.  In all other cases, it fails.</p>
</usage>

<seealso><a href="#logic">Authorization Containers</a></seealso>
<seealso><a href="../howto/auth.html">Authentication, Authorization,
    and Access Control</a></seealso>

</directivesynopsis>

<directivesynopsis type="section">
<name>RequireAny</name>
<description>Enclose a group of authorization directives of which one
must succeed for the enclosing directive to succeed.</description>
<syntax>&lt;RequireAny&gt; ... &lt;/RequireAny&gt;</syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p><directive type="section">RequireAny</directive> and
    <code>&lt;/RequireAny&gt;</code> are used to enclose a group of
    authorization directives of which one must succeed in order for
    the <directive type="section">RequireAny</directive> directive to
    succeed.</p>

    <p>If one or more of the directives contained within the
    <directive type="section">RequireAny</directive> directive succeed,
    then the <directive type="section">RequireAny</directive> directive
    succeeds.  If none succeed and none fail, then it returns a
    neutral result.  In all other cases, it fails.</p>

    <note>Because negated authorization directives are unable to
    return a successful result, they can not significantly influence
    the result of a <directive type="section">RequireAny</directive>
    directive.  (At most they could cause the directive to fail in
    the case where they failed and all other directives returned a
    neutral value.)  Therefore negated authorization directives
    are not permitted within a <directive type="section">RequireAny</directive>
    directive.</note>
</usage>

<seealso><a href="#logic">Authorization Containers</a></seealso>
<seealso><a href="../howto/auth.html">Authentication, Authorization,
    and Access Control</a></seealso>

</directivesynopsis>

<directivesynopsis type="section">
<name>RequireNone</name>
<description>Enclose a group of authorization directives of which none
must succeed for the enclosing directive to not fail.</description>
<syntax>&lt;RequireNone&gt; ... &lt;/RequireNone&gt;</syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p><directive type="section">RequireNone</directive> and
    <code>&lt;/RequireNone&gt;</code> are used to enclose a group of
    authorization directives of which none must succeed
    in order for the
    <directive type="section">RequireNone</directive> directive to
    not fail.</p>

    <p>If one or more of the directives contained within the
    <directive type="section">RequireNone</directive> directive succeed,
    then the <directive type="section">RequireNone</directive> directive
    fails.  In all other cases, it returns a neutral result.  Thus as with
    the other negated authorization directive <code>Require not</code>,
    it can never independently
    authorize a request because it can never return a successful result.
    It can be used, however, to restrict the set of users who are
    authorized to access a resource.</p>

    <note>Because negated authorization directives are unable to
    return a successful result, they can not significantly influence
    the result of a <directive type="section">RequireNone</directive>
    directive.  Therefore negated authorization directives
    are not permitted within a
    <directive type="section">RequireNone</directive> directive.</note>
</usage>

<seealso><a href="#logic">Authorization Containers</a></seealso>
<seealso><a href="../howto/auth.html">Authentication, Authorization,
    and Access Control</a></seealso>

</directivesynopsis>

<directivesynopsis>
<name>AuthMerging</name>
<description>Controls the manner in which each configuration section's
authorization logic is combined with that of preceding configuration
sections.</description>
<syntax>AuthMerging Off | And | Or</syntax>
<default>AuthMerging Off</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>When authorization is enabled, it is normally inherited by each
    subsequent <a href="../sections.html#merging">configuration section</a>,
    unless a different set of authorization directives are specified.
    This is the default action, which corresponds to an explicit setting
    of <code>AuthMerging Off</code>.</p>

    <p>However, there may be circumstances in which is it desirable
    for a configuration section's authorization to be combined with
    that of its predecessor while configuration sections are being
    merged.  Two options are available for this case, <code>And</code>
    and <code>Or</code>.</p>

    <p>When a configuration section contains <code>AuthMerging And</code>
    or <code>AuthMerging Or</code>,
    its authorization logic is combined with that of the nearest
    predecessor (according to the overall order of configuration sections)
    which also contains authorization logic as if the two sections
    were jointly contained within a
    <directive module="mod_authz_core" type="section">RequireAll</directive> or
    <directive module="mod_authz_core" type="section">RequireAny</directive>
    directive, respectively.</p>

    <note>The setting of <directive>AuthMerging</directive> is not
    inherited outside of the configuration section in which it appears.
    In the following example, only users belonging to group <code>alpha</code>
    may access <code>/www/docs</code>.  Users belonging to either
    groups <code>alpha</code> or <code>beta</code> may access
    <code>/www/docs/ab</code>.  However, the default <code>Off</code>
    setting of <directive>AuthMerging</directive> applies to the
    <directive type="section" module="core">Directory</directive>
    configuration section for <code>/www/docs/ab/gamma</code>, so
    that section's authorization directives override those of the
    preceding sections.  Thus only users belong to the group
    <code>gamma</code> may access <code>/www/docs/ab/gamma</code>.</note>

    <highlight language="config">
&lt;Directory /www/docs&gt;
    AuthType Basic
    AuthName Documents
    AuthBasicProvider file
    AuthUserFile /usr/local/apache/passwd/passwords
    Require group alpha
&lt;/Directory&gt;

&lt;Directory /www/docs/ab&gt;
    AuthMerging Or
    Require group beta
&lt;/Directory&gt;

&lt;Directory /www/docs/ab/gamma&gt;
    Require group gamma
&lt;/Directory&gt;
    </highlight>
</usage>

</directivesynopsis>

<directivesynopsis type="section">
<name>AuthzProviderAlias</name>
<description>Enclose a group of directives that represent an
extension of a base authorization provider and referenced by the specified
alias</description>
<syntax>&lt;AuthzProviderAlias <var>baseProvider Alias Require-Parameters</var>&gt;
... &lt;/AuthzProviderAlias&gt;
</syntax>
<contextlist><context>server config</context>
</contextlist>

<usage>
    <p><directive type="section">AuthzProviderAlias</directive> and
    <code>&lt;/AuthzProviderAlias&gt;</code> are used to enclose a group of
    authorization directives that can be referenced by the alias name using the
    directive <directive module="mod_authz_core">Require</directive>.</p>

</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthzSendForbiddenOnFailure</name>
<description>Send '403 FORBIDDEN' instead of '401 UNAUTHORIZED' if
authentication succeeds but authorization fails
</description>
<syntax>AuthzSendForbiddenOnFailure On|Off</syntax>
<default>AuthzSendForbiddenOnFailure Off</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<compatibility>Available in Apache HTTPD 2.3.11 and later</compatibility>

<usage>
    <p>If authentication succeeds but authorization fails, Apache HTTPD will
    respond with an HTTP response code of '401 UNAUTHORIZED' by default. This
    usually causes browsers to display the password dialogue to the user
    again, which is not wanted in all situations.
    <directive>AuthzSendForbiddenOnFailure</directive> allows to change the
    response code to '403 FORBIDDEN'.</p>

    <note type="warning"><title>Security Warning</title>
    <p>Modifying the response in case of missing authorization weakens the
    security of the password, because it reveals to a possible attacker, that
    his guessed password was right.</p>
    </note>
</usage>
</directivesynopsis>


</modulesynopsis>