mirror of
https://github.com/SELinuxProject/selinux
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12c7dfc553
Converting to github markdown allows for easier integration with the SELinux project wiki and viewing of documentation directly on github without creating PDFs or reading through DocBook XML. The conversion of DocBook to github markdown would not format tables or keyword links properly. By maintaining the documentation in github markdown in the repository, the content is well formatted with a table of contents when viewing in the github wiki or in the repository. The migration from DocBook to github markdown was done using Pandoc and manual fixups. Mappings of CIL keywords to headings that were lost in the DocBook conversion were added back. An introduction and design philosphy was also pulled from the SELinux project wiki to provide more cohesion to the current documentation. Running make will now convert the github markdown into PDF and HTML. Signed-off-by: Yuli Khodorkovskiy <ykhodorkovskiy@tresys.com>
223 lines
7.1 KiB
Markdown
223 lines
7.1 KiB
Markdown
Conditional Statements
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======================
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boolean
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-------
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Declares a run time boolean as true or false in the current namespace. The [`booleanif`](cil_conditional_statements.md#booleanif) statement contains the CIL code that will be in the binary policy file.
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**Statement definition:**
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(boolean boolean_id true|false)
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**Where:**
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<table>
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<colgroup>
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<col width="25%" />
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<col width="75%" />
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</colgroup>
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<tbody>
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<tr class="odd">
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<td align="left"><p><code>boolean</code></p></td>
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<td align="left"><p>The <code>boolean</code> keyword.</p></td>
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</tr>
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<tr class="even">
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<td align="left"><p><code>boolean_id</code></p></td>
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<td align="left"><p>The <code>boolean</code> identifier.</p></td>
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</tr>
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<tr class="odd">
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<td align="left"><p><code>true | false</code></p></td>
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<td align="left"><p>The initial state of the boolean. This can be changed at run time using <strong><code>setsebool</code></strong><code>(8)</code> and its status queried using <strong><code>getsebool</code></strong><code>(8)</code>.</p></td>
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</tr>
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</tbody>
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</table>
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**Example:**
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See the [`booleanif`](cil_conditional_statements.md#booleanif) statement for an example.
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booleanif
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---------
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Contains the run time conditional statements that are instantiated in the binary policy according to the computed boolean identifier(s) state.
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[`call`](cil_call_macro_statements.md#call) statements are allowed within a [`booleanif`](cil_conditional_statements.md#booleanif), however the contents of the resulting macro must be limited to those of the [`booleanif`](cil_conditional_statements.md#booleanif) statement (i.e. [`allow`](cil_access_vector_rules.md#allow), [`auditallow`](cil_access_vector_rules.md#auditallow), [`dontaudit`](cil_access_vector_rules.md#dontaudit), [`typemember`](cil_type_statements.md#typemember), [`typetransition`](cil_type_statements.md#typetransition), [`typechange`](cil_type_statements.md#typechange) and the compile time [`tunableif`](cil_conditional_statements.md#tunableif) statement)).
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**Statement definition:**
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(booleanif boolean_id | expr ...)
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(true
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cil_statements
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...)
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(false
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cil_statements
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...)
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)
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**Where:**
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<table>
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<colgroup>
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<col width="25%" />
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<col width="75%" />
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</colgroup>
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<tbody>
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<tr class="odd">
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<td align="left"><p><code>booleanif</code></p></td>
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<td align="left"><p>The <code>booleanif</code> keyword.</p></td>
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</tr>
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<tr class="even">
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<td align="left"><p><code>boolean_id</code></p></td>
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<td align="left"><p>Either a single <code>boolean</code> identifier or one or more <code>expr</code>'s.</p></td>
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</tr>
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<tr class="odd">
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<td align="left"><p><code>expr</code></p></td>
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<td align="left"><p>Zero or more <code>expr</code>'s, the valid operators and syntax are:</p>
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<p><code> (and (boolean_id boolean_id))</code></p>
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<p><code> (or (boolean_id boolean_id))</code></p>
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<p><code> (xor (boolean_id boolean_id))</code></p>
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<p><code> (eq (boolean_id boolean_id))</code></p>
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<p><code> (neq (boolean_id boolean_id))</code></p>
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<p><code> (not (boolean_id))</code></p></td>
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</tr>
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<tr class="even">
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<td align="left"><p><code>true</code></p></td>
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<td align="left"><p>An optional set of CIL statements that will be instantiated when the <code>boolean</code> is evaluated as <code>true</code>.</p></td>
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</tr>
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<tr class="odd">
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<td align="left"><p><code>false</code></p></td>
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<td align="left"><p>An optional set of CIL statements that will be instantiated when the <code>boolean</code> is evaluated as <code>false</code>.</p></td>
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</tr>
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</tbody>
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</table>
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**Examples:**
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The second example also shows the kernel policy language equivalent:
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(boolean disableAudio false)
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(booleanif disableAudio
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(false
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(allow process mediaserver.audio_device (chr_file_set (rw_file_perms)))
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)
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)
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(boolean disableAudioCapture false)
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;;; if(!disableAudio && !disableAudioCapture) {
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(booleanif (and (not disableAudio) (not disableAudioCapture))
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(true
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(allow process mediaserver.audio_capture_device (chr_file_set (rw_file_perms)))
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)
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)
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tunable
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-------
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Tunables are similar to booleans, however they are used to manage areas of CIL statements that may or may not be in the final CIL policy that will be compiled (whereas booleans are embedded in the binary policy and can be enabled or disabled during run-time).
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Note that tunables can be treated as booleans by the CIL compiler command line parameter `-P` or `--preserve-tunables` flags.
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**Statement definition:**
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(tunable tunable_id true|false)
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**Where:**
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<table>
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<colgroup>
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<col width="25%" />
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<col width="75%" />
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</colgroup>
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<tbody>
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<tr class="odd">
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<td align="left"><p><code>tunable</code></p></td>
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<td align="left"><p>The <code>tunable</code> keyword.</p></td>
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</tr>
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<tr class="even">
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<td align="left"><p><code>tunable_id</code></p></td>
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<td align="left"><p>The <code>tunable</code> identifier.</p></td>
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</tr>
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<tr class="odd">
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<td align="left"><p><code>true | false</code></p></td>
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<td align="left"><p>The initial state of the <code>tunable</code>.</p></td>
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</tr>
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</tbody>
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</table>
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**Example:**
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See the [`tunableif`](cil_conditional_statements.md#tunableif) statement for an example.
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tunableif
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---------
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Compile time conditional statement that may or may not add CIL statements to be compiled.
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**Statement definition:**
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(tunableif tunable_id | expr ...)
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(true
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cil_statements
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...)
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(false
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cil_statements
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...)
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)
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**Where:**
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<table>
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<colgroup>
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<col width="25%" />
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<col width="75%" />
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</colgroup>
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<tbody>
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<tr class="odd">
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<td align="left"><p><code>tunableif</code></p></td>
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<td align="left"><p>The <code>tunableif</code> keyword.</p></td>
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</tr>
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<tr class="even">
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<td align="left"><p><code>tunable_id</code></p></td>
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<td align="left"><p>Either a single <code>tunable</code> identifier or one or more <code>expr</code>'s.</p></td>
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</tr>
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<tr class="odd">
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<td align="left"><p><code>expr</code></p></td>
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<td align="left"><p>Zero or more <code>expr</code>'s, the valid operators and syntax are:</p>
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<p><code> (and (tunable_id tunable_id))</code></p>
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<p><code> (or (tunable_id tunable_id))</code></p>
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<p><code> (xor (tunable_id tunable_id))</code></p>
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<p><code> (eq (tunable_id tunable_id))</code></p>
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<p><code> (neq (tunable_id tunable_id))</code></p>
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<p><code> (not (tunable_id))</code></p></td>
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</tr>
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<tr class="even">
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<td align="left"><p><code>true</code></p></td>
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<td align="left"><p>An optional set of CIL statements that will be instantiated when the <code>tunable</code> is evaluated as <code>true</code>.</p></td>
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</tr>
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<tr class="odd">
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<td align="left"><p><code>false</code></p></td>
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<td align="left"><p>An optional set of CIL statements that will be instantiated when the <code>tunable</code> is evaluated as <code>false</code>.</p></td>
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</tr>
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</tbody>
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</table>
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**Example:**
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This example will not add the range transition rule to the binary policy:
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(tunable range_trans_rule false)
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(block init
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(class process (process))
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(type process)
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(tunableif range_trans_rule
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(true
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(rangetransition process sshd.exec process low_high)
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)
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) ; End tunableif
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) ; End block
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