cil/docs/cil_constraint_statements.xml

<!-- Common Interface Language (CIL) Reference Guide -->
           <!-- constraint_statements.xml -->

   <sect1>
      <title>Constraint Statements</title>
      <sect2 id="constrain">
         <title>constrain</title>
         <para>Enable constraints to be placed on the specified permissions of the object class based on the source and target security context components.</para>
         <para><emphasis role="bold">Statement definition:</emphasis></para>
         <programlisting><![CDATA[(constrain classpermissionset_id ... expression | expr ...)]]></programlisting>
         <para><emphasis role="bold">Where:</emphasis></para>
         <informaltable frame="all">
            <tgroup cols="2">
            <colspec colwidth="2.25 *"/>
            <colspec colwidth="6 *"/>
               <tbody>
               <row>
                  <entry>
                     <para><literal>constrain</literal></para>
                  </entry>
                  <entry>
                     <para>The <literal>constrain</literal> keyword.</para>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>classpermissionset_id</literal></para>
                  </entry>
                  <entry>
                     <para>A single named or anonymous <literal><link linkend="classpermissionset">classpermissionset</link></literal> or a single set of <literal><link linkend="classmap">classmap</link></literal>/<literal><link linkend="classmapping">classmapping</link></literal> identifiers.</para>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>expression</literal></para>
                  </entry>
                  <entry>
                     <para>There must be one constraint <literal>expression</literal> or one or more <literal>expr</literal>'s. The expression consists of an operator and two operands as follows:</para>
                        <simpara><literal>    (op u1 u2)</literal></simpara>
                        <simpara><literal>    (role_op r1 r2)</literal></simpara>
                        <simpara><literal>    (op t1 t2)</literal></simpara>
                        <simpara><literal>    (op u1 user_id)</literal></simpara>
                        <simpara><literal>    (op u2 user_id)</literal></simpara>
                        <simpara><literal>    (op r1 role_id)</literal></simpara>
                        <simpara><literal>    (op r2 role_id)</literal></simpara>
                        <simpara><literal>    (op t1 type_id)</literal></simpara>
                        <simpara><literal>    (op t2 type_id)</literal></simpara>
                     <simpara>where:</simpara>
                        <simpara><literal>  u1, r1, t1 = Source context: <link linkend="user">user</link>, <link linkend="role">role</link> or <link linkend="type">type</link></literal></simpara>
                        <simpara><literal>  u2, r2, t2 = Target context: <link linkend="user">user</link>, <link linkend="role">role</link> or <link linkend="type">type</link></literal></simpara>
                     <simpara>and:</simpara>
                        <simpara><literal>  op      : eq neq</literal></simpara>
                        <simpara><literal>  role_op : eq neq dom domby incomp</literal></simpara>
                        <simpara><literal>  user_id : A single <link linkend="user">user</link> identifier.</literal></simpara>
                        <simpara><literal>  role_id : A single <link linkend="role">role</link> or <link linkend="roleattribute">roleattribute</link> identifier.</literal></simpara>
                        <simpara><literal>  type_id : A single <link linkend="type">type</link>, <link linkend="typealias">typealias</link> or <link linkend="typeattribute">typeattribute</link> identifier.</literal></simpara>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>expr</literal></para>
                  </entry>
                  <entry>
                     <para>Zero or more <literal>expr</literal>'s, the valid operators and syntax are:</para>
                     <simpara><literal>    (and expression expression)</literal></simpara>
                     <simpara><literal>    (or  expression expression)</literal></simpara>
                     <simpara><literal>    (not expression)</literal></simpara>
                  </entry>
               </row>
            </tbody></tgroup>
         </informaltable>

         <para><emphasis role="bold">Examples:</emphasis></para>
         <para>Two constrain statements are shown with their equivalent kernel policy language statements:</para>
         <programlisting><![CDATA[
;; constrain { file } { write }
;;    (( t1 == unconfined.process  ) and ( t2 == unconfined.object  ) or ( r1 eq r2 ));
(constrain (file (write))
    (or
        (and
            (eq t1 unconfined.process)
            (eq t2 unconfined.object)
        )
        (eq r1 r2)
    )
)

;; constrain { file } { read }
;;    (not( t1 == unconfined.process  ) and ( t2 == unconfined.object  ) or ( r1 eq r2 ));
(constrain (file (read))
    (not
        (or
            (and
                (eq t1 unconfined.process)
                (eq t2 unconfined.object)
            )
            (eq r1 r2)
        )
    )
)]]>
         </programlisting>
      </sect2>

      <sect2 id="validatetrans">
         <title>validatetrans</title>
         <para>The <literal>validatetrans</literal> statement is only used for <literal>file</literal> related object classes where it is used to control the ability to change the objects security context based on old, new and the current process security context.</para>
         <para><emphasis role="bold">Statement definition:</emphasis></para>
         <programlisting><![CDATA[(validatetrans class_id expression | expr ...)]]>
         </programlisting>
         <para><emphasis role="bold">Where:</emphasis></para>
         <informaltable frame="all">
            <tgroup cols="2">
            <colspec colwidth="2 *"/>
            <colspec colwidth="6 *"/>
               <tbody>
               <row>
                  <entry>
                     <para><literal>validatetrans</literal></para>
                  </entry>
                  <entry>
                     <para>The <literal>validatetrans</literal> keyword.</para>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>class_id</literal></para>
                  </entry>
                  <entry>
                     <para>A single previously declared <literal><link linkend="class">class</link></literal> or <literal><link linkend="classmap">classmap</link></literal> identifier.</para>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>expression</literal></para>
                  </entry>
                  <entry>
                     <para>There must be one constraint <literal>expression</literal> or one or more <literal>expr</literal>'s. The expression consists of an operator and two operands as follows:</para>
                        <simpara><literal>    (op u1 u2)</literal></simpara>
                        <simpara><literal>    (role_op r1 r2)</literal></simpara>
                        <simpara><literal>    (op t1 t2)</literal></simpara>
                        <simpara><literal>    (op u1 user_id)</literal></simpara>
                        <simpara><literal>    (op u2 user_id)</literal></simpara>
                        <simpara><literal>    (op u3 user_id)</literal></simpara>
                        <simpara><literal>    (op r1 role_id)</literal></simpara>
                        <simpara><literal>    (op r2 role_id)</literal></simpara>
                        <simpara><literal>    (op r3 role_id)</literal></simpara>
                        <simpara><literal>    (op t1 type_id)</literal></simpara>
                        <simpara><literal>    (op t2 type_id)</literal></simpara>
                        <simpara><literal>    (op t3 type_id)</literal></simpara>
                     <simpara>where:</simpara>
                        <simpara><literal>  u1, r1, t1 = Old context: <link linkend="user">user</link>, <link linkend="role">role</link> or <link linkend="type">type</link></literal></simpara>
                        <simpara><literal>  u2, r2, t2 = New context: <link linkend="user">user</link>, <link linkend="role">role</link> or <link linkend="type">type</link></literal></simpara>
                        <simpara><literal>  u3, r3, t3 = Process context: <link linkend="user">user</link>, <link linkend="role">role</link> or <link linkend="type">type</link></literal></simpara>
                     <simpara>and:</simpara>
                        <simpara><literal>  op      : eq neq</literal></simpara>
                        <simpara><literal>  role_op : eq neq dom domby incomp</literal></simpara>
                        <simpara><literal>  user_id : A single <link linkend="user">user</link> identifier.</literal></simpara>
                        <simpara><literal>  role_id : A single <link linkend="role">role</link> or <link linkend="roleattribute">roleattribute</link> identifier.</literal></simpara>
                        <simpara><literal>  type_id : A single <link linkend="type">type</link>, <link linkend="typealias">typealias</link> or <link linkend="typeattribute">typeattribute</link> identifier.</literal></simpara>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>expr</literal></para>
                  </entry>
                  <entry>
                     <para>Zero or more <literal>expr</literal>'s, the valid operators and syntax are:</para>
                     <simpara><literal>    (and expression expression)</literal></simpara>
                     <simpara><literal>    (or  expression expression)</literal></simpara>
                     <simpara><literal>    (not expression)</literal></simpara>
                  </entry>
               </row>
            </tbody></tgroup>
         </informaltable>

         <para><emphasis role="bold">Example:</emphasis></para>
         <para>A validate transition statement with the equivalent kernel policy language statement:</para>
         <programlisting><![CDATA[
; validatetrans { file } ( t1 == unconfined.process  );

(validatetrans file (eq t1 unconfined.process))]]>
      </programlisting>
      </sect2>

      <sect2 id="mlsconstrain">
         <title>mlsconstrain</title>
         <para>Enable MLS constraints to be placed on the specified permissions of the object class based on the source and target security context components.</para>
         <para><emphasis role="bold">Statement definition:</emphasis></para>
         <programlisting><![CDATA[(mlsconstrain classpermissionset_id ... expression | expr ...)]]></programlisting>
         <para><emphasis role="bold">Where:</emphasis></para>
         <informaltable frame="all">
            <tgroup cols="2">
            <colspec colwidth="2.25 *"/>
            <colspec colwidth="6 *"/>
               <tbody>
               <row>
                  <entry>
                     <para><literal>mlsconstrain</literal></para>
                  </entry>
                  <entry>
                     <para>The <literal>mlsconstrain</literal> keyword.</para>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>classpermissionset_id</literal></para>
                  </entry>
                  <entry>
                     <para>A single named or anonymous <literal><link linkend="classpermissionset">classpermissionset</link></literal> or a single set of <literal><link linkend="classmap">classmap</link></literal>/<literal><link linkend="classmapping">classmapping</link></literal> identifiers.</para>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>expression</literal></para>
                  </entry>
                  <entry>
                     <para>There must be one constraint <literal>expression</literal> or one or more <literal>expr</literal>'s. The expression consists of an operator and two operands as follows:</para>
                        <simpara><literal>    (op u1 u2)</literal></simpara>
                        <simpara><literal>    (mls_role_op r1 r2)</literal></simpara>
                        <simpara><literal>    (op t1 t2)</literal></simpara>
                        <simpara><literal>    (mls_role_op l1 l2)</literal></simpara>
                        <simpara><literal>    (mls_role_op l1 h2)</literal></simpara>
                        <simpara><literal>    (mls_role_op h1 l2)</literal></simpara>
                        <simpara><literal>    (mls_role_op h1 h2)</literal></simpara>
                        <simpara><literal>    (mls_role_op l1 h1)</literal></simpara>
                        <simpara><literal>    (mls_role_op l2 h2)</literal></simpara>
                        <simpara><literal>    (op u1 user_id)</literal></simpara>
                        <simpara><literal>    (op u2 user_id)</literal></simpara>
                        <simpara><literal>    (op r1 role_id)</literal></simpara>
                        <simpara><literal>    (op r2 role_id)</literal></simpara>
                        <simpara><literal>    (op t1 type_id)</literal></simpara>
                        <simpara><literal>    (op t2 type_id)</literal></simpara>
                     <simpara>where:</simpara>
                        <simpara><literal>  u1, r1, t1, l1, h1 = Source context: <link linkend="user">user</link>, <link linkend="role">role</link>, <link linkend="type">type</link>, <link linkend="level">low level</link> or <link linkend="level">high level</link></literal></simpara>
                        <simpara><literal>  u2, r2, t2, l2, h2 = Target context: <link linkend="user">user</link>, <link linkend="role">role</link>, <link linkend="type">type</link>, <link linkend="level">low level</link> or <link linkend="level">high level</link></literal></simpara>
                     <simpara>and:</simpara>
                        <simpara><literal>  op          : eq neq</literal></simpara>
                        <simpara><literal>  mls_role_op : eq neq dom domby incomp</literal></simpara>
                        <simpara><literal>  user_id     : A single <link linkend="user">user</link> identifier.</literal></simpara>
                        <simpara><literal>  role_id     : A single <link linkend="role">role</link> or <link linkend="roleattribute">roleattribute</link> identifier.</literal></simpara>
                        <simpara><literal>  type_id     : A single <link linkend="type">type</link>, <link linkend="typealias">typealias</link> or <link linkend="typeattribute">typeattribute</link> identifier.</literal></simpara>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>expr</literal></para>
                  </entry>
                  <entry>
                     <para>Zero or more <literal>expr</literal>'s, the valid operators and syntax are:</para>
                     <simpara><literal>    (and expression expression)</literal></simpara>
                     <simpara><literal>    (or  expression expression)</literal></simpara>
                     <simpara><literal>    (not expression)</literal></simpara>
                  </entry>
               </row>
            </tbody></tgroup>
         </informaltable>

         <para><emphasis role="bold">Example:</emphasis></para>
         <para>An MLS constrain statement with the equivalent kernel policy language statement:</para>
         <programlisting><![CDATA[
;; mlsconstrain { file } { open }
;;     (( l1 eq l2 ) and ( u1 == u2 ) or ( r1 != r2 ));

(mlsconstrain (file (open))
    (or
        (and
            (eq l1 l2)
            (eq u1 u2)
        )
        (neq r1 r2)
    )
)]]>
         </programlisting>
      </sect2>

      <sect2 id="mlsvalidatetrans">
         <title>mlsvalidatetrans</title>
         <para>The <literal>mlsvalidatetrans</literal> statement is only used for <literal>file</literal> related object classes where it is used to control the ability to change the objects security context based on old, new and the current process security context.</para>
         <para><emphasis role="bold">Statement definition:</emphasis></para>
         <programlisting><![CDATA[(mlsvalidatetrans class_id expression | expr ...)]]>
         </programlisting>
         <para><emphasis role="bold">Where:</emphasis></para>
         <informaltable frame="all">
            <tgroup cols="2">
            <colspec colwidth="2 *"/>
            <colspec colwidth="6 *"/>
               <tbody>
               <row>
                  <entry>
                     <para><literal>mlsvalidatetrans</literal></para>
                  </entry>
                  <entry>
                     <para>The <literal>mlsvalidatetrans</literal> keyword.</para>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>class_id</literal></para>
                  </entry>
                  <entry>
                     <para>A single previously declared <literal><link linkend="class">class</link></literal> or <literal><link linkend="classmap">classmap</link></literal> identifier.</para>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>expression</literal></para>
                  </entry>
                  <entry>
                     <para>There must be one constraint <literal>expression</literal> or one or more <literal>expr</literal>'s. The expression consists of an operator and two operands as follows:</para>
                        <simpara><literal>    (op u1 u2)</literal></simpara>
                        <simpara><literal>    (mls_role_op r1 r2)</literal></simpara>
                        <simpara><literal>    (op t1 t2)</literal></simpara>
                        <simpara><literal>    (mls_role_op l1 l2)</literal></simpara>
                        <simpara><literal>    (mls_role_op l1 h2)</literal></simpara>
                        <simpara><literal>    (mls_role_op h1 l2)</literal></simpara>
                        <simpara><literal>    (mls_role_op h1 h2)</literal></simpara>
                        <simpara><literal>    (mls_role_op l1 h1)</literal></simpara>
                        <simpara><literal>    (mls_role_op l2 h2)</literal></simpara>
                        <simpara><literal>    (op u1 user_id)</literal></simpara>
                        <simpara><literal>    (op u2 user_id)</literal></simpara>
                        <simpara><literal>    (op u3 user_id)</literal></simpara>
                        <simpara><literal>    (op r1 role_id)</literal></simpara>
                        <simpara><literal>    (op r2 role_id)</literal></simpara>
                        <simpara><literal>    (op r3 role_id)</literal></simpara>
                        <simpara><literal>    (op t1 type_id)</literal></simpara>
                        <simpara><literal>    (op t2 type_id)</literal></simpara>
                        <simpara><literal>    (op t3 type_id)</literal></simpara>
                     <simpara>where:</simpara>
                        <simpara><literal>  u1, r1, t1, l1, h1 = Source context: <link linkend="user">user</link>, <link linkend="role">role</link>, <link linkend="type">type</link>, <link linkend="level">low level</link> or <link linkend="level">high level</link></literal></simpara>
                        <simpara><literal>  u2, r2, t2, l2, h2 = Target context: <link linkend="user">user</link>, <link linkend="role">role</link>, <link linkend="type">type</link>, <link linkend="level">low level</link> or <link linkend="level">high level</link></literal></simpara>
                        <simpara><literal>  u3, r3, t3         = Process context: <link linkend="user">user</link>, <link linkend="role">role</link> or <link linkend="type">type</link></literal></simpara>
                     <simpara>and:</simpara>
                        <simpara><literal>  op          : eq neq</literal></simpara>
                        <simpara><literal>  mls_role_op : eq neq dom domby incomp</literal></simpara>
                        <simpara><literal>  user_id     : A single <link linkend="user">user</link> identifier.</literal></simpara>
                        <simpara><literal>  role_id     : A single <link linkend="role">role</link> or <link linkend="roleattribute">roleattribute</link> identifier.</literal></simpara>
                        <simpara><literal>  type_id     : A single <link linkend="type">type</link>, <link linkend="typealias">typealias</link> or <link linkend="typeattribute">typeattribute</link> identifier.</literal></simpara>
                  </entry>
               </row>
               <row>
                  <entry>
                     <para><literal>expr</literal></para>
                  </entry>
                  <entry>
                     <para>Zero or more <literal>expr</literal>'s, the valid operators and syntax are:</para>
                     <simpara><literal>    (and expression expression)</literal></simpara>
                     <simpara><literal>    (or  expression expression)</literal></simpara>
                     <simpara><literal>    (not expression)</literal></simpara>
                  </entry>
               </row>
            </tbody></tgroup>
         </informaltable>

         <para><emphasis role="bold">Example:</emphasis></para>
         <para>An MLS validate transition statement with the equivalent kernel policy language statement:</para>
         <programlisting><![CDATA[
;; mlsvalidatetrans { file } ( l1 domby h2 );

(mlsvalidatetrans file (domby l1 h2))]]>
      </programlisting>
      </sect2>

   </sect1>