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<title>[42011] trunk: Filesystem API: Add more specificity to the rules for valid files in `validate_file()`.</title>
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<dt style="float: left; width: 6em; font-weight: bold">Revision</dt> <dd><a style="font-weight: bold" href="https://core.trac.wordpress.org/changeset/42011">42011</a><script type="application/ld+json">{"@context":"http://schema.org","@type":"EmailMessage","description":"Review this Commit","action":{"@type":"ViewAction","url":"https://core.trac.wordpress.org/changeset/42011","name":"Review Commit"}}</script></dd>
<dt style="float: left; width: 6em; font-weight: bold">Author</dt> <dd>johnbillion</dd>
<dt style="float: left; width: 6em; font-weight: bold">Date</dt> <dd>2017-10-24 23:14:33 +0000 (Tue, 24 Oct 2017)</dd>
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<pre style='padding-left: 1em; margin: 2em 0; border-left: 2px solid #ccc; line-height: 1.25; font-size: 105%; font-family: sans-serif'>Filesystem API: Add more specificity to the rules for valid files in `validate_file()`.
This now treats files containing `./` as valid, and also treats files containing a trailing `../` as valid due to widespread use of this pattern in theme and plugin zip files.
Adds tests.
Props Ipstenu, borgesbruno, DavidAnderson, philipjohn, birgire
Fixes <a href="https://core.trac.wordpress.org/ticket/42016">#42016</a>, <a href="https://core.trac.wordpress.org/ticket/36170">#36170</a></pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunksrcwpadminincludesfilephp">trunk/src/wp-admin/includes/file.php</a></li>
<li><a href="#trunksrcwpincludesfunctionsphp">trunk/src/wp-includes/functions.php</a></li>
<li><a href="#trunktestsphpunittestsfunctionsphp">trunk/tests/phpunit/tests/functions.php</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunksrcwpadminincludesfilephp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/src/wp-admin/includes/file.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/src/wp-admin/includes/file.php 2017-10-24 23:10:37 UTC (rev 42010)
+++ trunk/src/wp-admin/includes/file.php 2017-10-24 23:14:33 UTC (rev 42011)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -663,7 +663,7 @@
</span><span class="cx" style="display: block; padding: 0 10px"> * @param array $allowed_files Optional. Array of allowed files to edit, $file must match an entry exactly.
</span><span class="cx" style="display: block; padding: 0 10px"> * @return string|null
</span><span class="cx" style="display: block; padding: 0 10px"> */
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-function validate_file_to_edit( $file, $allowed_files = '' ) {
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+function validate_file_to_edit( $file, $allowed_files = array() ) {
</ins><span class="cx" style="display: block; padding: 0 10px"> $code = validate_file( $file, $allowed_files );
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> if (!$code )
</span></span></pre></div>
<a id="trunksrcwpincludesfunctionsphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/src/wp-includes/functions.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/src/wp-includes/functions.php 2017-10-24 23:10:37 UTC (rev 42010)
+++ trunk/src/wp-includes/functions.php 2017-10-24 23:14:33 UTC (rev 42011)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -4252,16 +4252,27 @@
</span><span class="cx" style="display: block; padding: 0 10px"> * @param array $allowed_files Optional. List of allowed files.
</span><span class="cx" style="display: block; padding: 0 10px"> * @return int 0 means nothing is wrong, greater than 0 means something was wrong.
</span><span class="cx" style="display: block; padding: 0 10px"> */
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-function validate_file( $file, $allowed_files = '' ) {
- if ( false !== strpos( $file, '..' ) )
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+function validate_file( $file, $allowed_files = array() ) {
+ // `../` on its own is not allowed:
+ if ( '../' === $file ) {
</ins><span class="cx" style="display: block; padding: 0 10px"> return 1;
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ }
</ins><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- if ( false !== strpos( $file, './' ) )
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ // More than one occurence of `../` is not allowed:
+ if ( preg_match_all( '#\.\./#', $file, $matches, PREG_SET_ORDER ) && ( count( $matches ) > 1 ) ) {
</ins><span class="cx" style="display: block; padding: 0 10px"> return 1;
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ }
</ins><span class="cx" style="display: block; padding: 0 10px">
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ // `../` which does not occur at the end of the path is not allowed:
+ if ( false !== strpos( $file, '../' ) && '../' !== mb_substr( $file, -3, 3 ) ) {
+ return 1;
+ }
+
+ // Files not in the allowed file list are not allowed:
</ins><span class="cx" style="display: block; padding: 0 10px"> if ( ! empty( $allowed_files ) && ! in_array( $file, $allowed_files ) )
</span><span class="cx" style="display: block; padding: 0 10px"> return 3;
</span><span class="cx" style="display: block; padding: 0 10px">
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ // Absolute Windows drive paths are not allowed:
</ins><span class="cx" style="display: block; padding: 0 10px"> if (':' == substr( $file, 1, 1 ) )
</span><span class="cx" style="display: block; padding: 0 10px"> return 2;
</span><span class="cx" style="display: block; padding: 0 10px">
</span></span></pre></div>
<a id="trunktestsphpunittestsfunctionsphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/tests/phpunit/tests/functions.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/tests/phpunit/tests/functions.php 2017-10-24 23:10:37 UTC (rev 42010)
+++ trunk/tests/phpunit/tests/functions.php 2017-10-24 23:14:33 UTC (rev 42011)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -1161,4 +1161,147 @@
</span><span class="cx" style="display: block; padding: 0 10px"> return $data;
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ /**
+ * Test file path validation
+ *
+ * @ticket 42016
+ * @dataProvider data_test_validate_file()
+ *
+ * @param string $file File path.
+ * @param array $allowed_files List of allowed files.
+ * @param int $expected Expected result.
+ */
+ public function test_validate_file( $file, $allowed_files, $expected ) {
+ $this->assertSame( $expected, validate_file( $file, $allowed_files ) );
+ }
+
+ /**
+ * Data provider for file validation.
+ *
+ * @return array {
+ * @type array $0... {
+ * @type string $0 File path.
+ * @type array $1 List of allowed files.
+ * @type int $2 Expected result.
+ * }
+ * }
+ */
+ public function data_test_validate_file() {
+ return array(
+
+ // Allowed files:
+ array(
+ null,
+ array(),
+ 0,
+ ),
+ array(
+ '',
+ array(),
+ 0,
+ ),
+ array(
+ ' ',
+ array(),
+ 0,
+ ),
+ array(
+ '.',
+ array(),
+ 0,
+ ),
+ array(
+ '..',
+ array(),
+ 0,
+ ),
+ array(
+ './',
+ array(),
+ 0,
+ ),
+ array(
+ 'foo.ext',
+ array( 'foo.ext' ),
+ 0,
+ ),
+ array(
+ 'dir/foo.ext',
+ array(),
+ 0,
+ ),
+ array(
+ 'foo..ext',
+ array(),
+ 0,
+ ),
+ array(
+ 'dir/dir/../',
+ array(),
+ 0,
+ ),
+
+ // Directory traversal:
+ array(
+ '../',
+ array(),
+ 1,
+ ),
+ array(
+ '../../',
+ array(),
+ 1,
+ ),
+ array(
+ '../file.ext',
+ array(),
+ 1,
+ ),
+ array(
+ '../dir/../',
+ array(),
+ 1,
+ ),
+ array(
+ '/dir/dir/../../',
+ array(),
+ 1,
+ ),
+ array(
+ '/dir/dir/../../',
+ array( '/dir/dir/../../' ),
+ 1,
+ ),
+
+ // Windows drives:
+ array(
+ 'c:',
+ array(),
+ 2,
+ ),
+ array(
+ 'C:/WINDOWS/system32',
+ array( 'C:/WINDOWS/system32' ),
+ 2,
+ ),
+
+ // Disallowed files:
+ array(
+ 'foo.ext',
+ array( 'bar.ext' ),
+ 3,
+ ),
+ array(
+ 'foo.ext',
+ array( '.ext' ),
+ 3,
+ ),
+ array(
+ 'path/foo.ext',
+ array( 'foo.ext' ),
+ 3,
+ ),
+
+ );
+ }
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span></span></pre>
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