236 lines
9.4 KiB
Diff
236 lines
9.4 KiB
Diff
From 89a75b024e45f687b1152fbb89ea47f7cbad75ce Mon Sep 17 00:00:00 2001
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From: Michael Simacek <msimacek@redhat.com>
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Date: Tue, 26 Jun 2018 15:17:33 +0200
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Subject: [PATCH] Fix arbitrary file write vulnerability
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---
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WHATSNEW | 18 +++++++
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manual/Tasks/unzip.html | 12 ++++-
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.../org/apache/tools/ant/taskdefs/Expand.java | 37 ++++++++++++--
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src/tests/antunit/taskdefs/unzip-test.xml | 46 ++++++++++++++++++
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.../taskdefs/zip/direscape-absolute.zip | Bin 0 -> 332 bytes
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src/tests/antunit/taskdefs/zip/direscape.zip | Bin 0 -> 332 bytes
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6 files changed, 109 insertions(+), 4 deletions(-)
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create mode 100644 src/tests/antunit/taskdefs/zip/direscape-absolute.zip
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create mode 100644 src/tests/antunit/taskdefs/zip/direscape.zip
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diff --git a/WHATSNEW b/WHATSNEW
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index 1e9b3398b..1ff99fc98 100644
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--- a/WHATSNEW
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+++ b/WHATSNEW
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@@ -1,3 +1,21 @@
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+Backported changes
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+==================
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+
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+Changes that could break older environments:
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+-------------------------------------------
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+
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+ * <unzip>, <unjar> and <untar> will no longer extract entries whose
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+ names would make the created files be placed outside of the
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+ destination directory anymore by default. A new attribute
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+ allowFilesToEscapeDest can be used to override the behavior.
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+ Another special case is when stripAbsolutePathSpec is false (which
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+ no longer is the default) and the entry's name starts with a
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+ (back)slash and allowFilesToEscapeDest hasn't been specified
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+ explicitly, in this case the file may be created outside of the
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+ dest directory as well.
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+ In addition stripAbsolutePathSpec is now true by default.
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+ Based on a recommendation by the Snyk Security Research Team.
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+
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Changes from Ant 1.9.3 TO Ant 1.9.4
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===================================
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diff --git a/manual/Tasks/unzip.html b/manual/Tasks/unzip.html
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index 02df7acf9..a5fc40fd3 100644
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--- a/manual/Tasks/unzip.html
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+++ b/manual/Tasks/unzip.html
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@@ -125,7 +125,8 @@ archive.</p>
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Note that this changes the entry's name before applying
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include/exclude patterns and before using the nested mappers (if
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any). <em>since Ant 1.8.0</em></td>
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- <td valign="top" align="center">No, defaults to false</td>
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+ <td valign="top" align="center">No, defaults to true since 1.9.12
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+ (used to defaukt to false prior to that)</td>
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</tr>
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<tr>
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<td valign="top">scanForUnicodeExtraFields</td>
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@@ -137,6 +138,15 @@ archive.</p>
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zip task page</a></td>
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<td align="center" valign="top">No, defaults to true</td>
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</tr>
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+ <tr>
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+ <td valign="top">allowFilesToEscapeDest</td>
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+ <td valign="top">Whether to allow the extracted file or directory
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+ to be outside of the dest directory.
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+ <em>since Ant 1.9.12</em></td>
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+ <td valign="top" align="center">No, defaults to false unless
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+ stripAbsolutePathSpec is true and the entry's name starts with a leading
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+ path spec.</td>
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+ </tr>
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</table>
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<h3>Examples</h3>
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<pre>
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diff --git a/src/main/org/apache/tools/ant/taskdefs/Expand.java b/src/main/org/apache/tools/ant/taskdefs/Expand.java
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index 8722e2402..ac5287cb8 100644
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--- a/src/main/org/apache/tools/ant/taskdefs/Expand.java
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+++ b/src/main/org/apache/tools/ant/taskdefs/Expand.java
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@@ -67,8 +67,9 @@ public class Expand extends Task {
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private Union resources = new Union();
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private boolean resourcesSpecified = false;
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private boolean failOnEmptyArchive = false;
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- private boolean stripAbsolutePathSpec = false;
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+ private boolean stripAbsolutePathSpec = true;
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private boolean scanForUnicodeExtraFields = true;
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+ private Boolean allowFilesToEscapeDest = null;
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public static final String NATIVE_ENCODING = "native-encoding";
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@@ -240,14 +241,17 @@ public class Expand extends Task {
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boolean isDirectory, FileNameMapper mapper)
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throws IOException {
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- if (stripAbsolutePathSpec && entryName.length() > 0
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+ final boolean entryNameStartsWithPathSpec = entryName.length() > 0
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&& (entryName.charAt(0) == File.separatorChar
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|| entryName.charAt(0) == '/'
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- || entryName.charAt(0) == '\\')) {
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+ || entryName.charAt(0) == '\\');
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+ if (stripAbsolutePathSpec && entryNameStartsWithPathSpec) {
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log("stripped absolute path spec from " + entryName,
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Project.MSG_VERBOSE);
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entryName = entryName.substring(1);
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}
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+ boolean allowedOutsideOfDest = Boolean.TRUE == getAllowFilesToEscapeDest()
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+ || null == getAllowFilesToEscapeDest() && !stripAbsolutePathSpec && entryNameStartsWithPathSpec;
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if (patternsets != null && patternsets.size() > 0) {
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String name = entryName.replace('/', File.separatorChar)
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@@ -313,6 +317,12 @@ public class Expand extends Task {
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mappedNames = new String[] {entryName};
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}
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File f = fileUtils.resolveFile(dir, mappedNames[0]);
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+ if (!allowedOutsideOfDest && !fileUtils.isLeadingPath(dir, f)) {
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+ log("skipping " + entryName + " as its target " + f + " is outside of "
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+ + dir + ".", Project.MSG_VERBOSE);
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+ return;
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+ }
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+
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try {
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if (!overwrite && f.exists()
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&& f.lastModified() >= entryDate.getTime()) {
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@@ -508,4 +518,25 @@ public class Expand extends Task {
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return scanForUnicodeExtraFields;
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}
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+ /**
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+ * Whether to allow the extracted file or directory to be outside of the dest directory.
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+ *
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+ * @param b the flag
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+ * @since Ant 1.9.12
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+ */
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+ public void setAllowFilesToEscapeDest(boolean b) {
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+ allowFilesToEscapeDest = b;
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+ }
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+
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+ /**
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+ * Whether to allow the extracted file or directory to be outside of the dest directory.
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+ *
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+ * @return {@code null} if the flag hasn't been set explicitly,
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+ * otherwise the value set by the user.
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+ * @since Ant 1.9.12
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+ */
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+ public Boolean getAllowFilesToEscapeDest() {
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+ return allowFilesToEscapeDest;
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+ }
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+
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}
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diff --git a/src/tests/antunit/taskdefs/unzip-test.xml b/src/tests/antunit/taskdefs/unzip-test.xml
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index b2c2105dd..bdf5f61e1 100644
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--- a/src/tests/antunit/taskdefs/unzip-test.xml
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+++ b/src/tests/antunit/taskdefs/unzip-test.xml
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@@ -24,6 +24,10 @@
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<mkdir dir="${output}" />
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</target>
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+ <target name="tearDown" depends="antunit-base.tearDown">
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+ <delete dir="/tmp/testdir"/>
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+ </target>
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+
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<target name="testFailureOnBrokenCentralDirectoryStructure">
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<au:expectfailure
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expectedmessage="central directory is empty, can't expand corrupt archive.">
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@@ -67,4 +71,46 @@
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<!-- failed on Windows and other OSes with implicit file locking -->
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<au:assertFileDoesntExist file="${input}/test.zip"/>
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</target>
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+
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+ <target name="testEntriesDontEscapeDestByDefault">
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+ <mkdir dir="${input}/"/>
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+ <mkdir dir="${output}/"/>
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+ <unzip src="zip/direscape.zip" dest="${output}"/>
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+ <au:assertFileDoesntExist file="${input}/a"/>
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+ </target>
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+
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+ <target name="testEntriesCanEscapeDestIfRequested">
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+ <mkdir dir="${input}/"/>
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+ <mkdir dir="${output}/"/>
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+ <unzip src="zip/direscape.zip" dest="${output}" allowFilesToEscapeDest="true"/>
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+ <au:assertFileExists file="${input}/a"/>
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+ </target>
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+
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+ <target name="-can-write-to-tmp?">
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+ <mkdir dir="${input}"/>
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+ <echo file="${input}/A.java"><![CDATA[
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+public class A {
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+ public static void main(String[] args) {
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+ new java.io.File("/tmp/testdir/").mkdirs();
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+ }
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+}
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+]]></echo>
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+ <mkdir dir="${output}"/>
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+ <javac srcdir="${input}" destdir="${output}"/>
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+ <java classname="A" classpath="${output}"/>
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+ <available property="can-write-to-tmp!" file="/tmp/testdir/"/>
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+ </target>
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+
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+ <target name="testEntriesCanEscapeDestViaAbsolutePathIfPermitted"
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+ depends="-can-write-to-tmp?" if="can-write-to-tmp!">
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+ <unzip src="zip/direscape-absolute.zip" dest="${output}"
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+ stripAbsolutePathSpec="false"/>
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+ <au:assertFileExists file="/tmp/testdir/a"/>
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+ </target>
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+
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+ <target name="testEntriesDontEscapeDestViaAbsolutePathByDefault"
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+ depends="-can-write-to-tmp?" if="can-write-to-tmp!">
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+ <unzip src="zip/direscape-absolute.zip" dest="${output}"/>
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+ <au:assertFileDoesntExist file="/tmp/testdir/a"/>
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+ </target>
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</project>
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diff --git a/src/tests/antunit/taskdefs/zip/direscape-absolute.zip b/src/tests/antunit/taskdefs/zip/direscape-absolute.zip
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new file mode 100644
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index 000000000..0bae4aaf1
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--- /dev/null
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+++ b/src/tests/antunit/taskdefs/zip/direscape-absolute.zip
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@@ -0,0 +1,5 @@
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+PK
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+ <00><><EFBFBD>L
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/tmp/testdir/UT 7l<37>Zn<>Zux <04> <04> PK
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+ <00><><EFBFBD>L /tmp/testdir/aUT 7l<37>ZJl<4A>Zux <04> <04> PK
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+ <00><><EFBFBD>L
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<00>A /tmp/testdir/UT 7l<37>Zux <04> <04> PK
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+ <00><><EFBFBD>L <00><>G /tmp/testdir/aUT 7l<37>Zux <04> <04> PK <00> <00>
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\ No newline at end of file
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diff --git a/src/tests/antunit/taskdefs/zip/direscape.zip b/src/tests/antunit/taskdefs/zip/direscape.zip
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new file mode 100644
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index 000000000..63cefd2d8
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--- /dev/null
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+++ b/src/tests/antunit/taskdefs/zip/direscape.zip
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@@ -0,0 +1,5 @@
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+PK
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+ <00><><EFBFBD>L
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../testinput/UT 7l<37>Zn<>Zux <04> <04> PK
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+ <00><><EFBFBD>L ../testinput/aUT 7l<37>ZJl<4A>Zux <04> <04> PK
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+ <00><><EFBFBD>L
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<00>A ../testinput/UT 7l<37>Zux <04> <04> PK
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+ <00><><EFBFBD>L <00><>G ../testinput/aUT 7l<37>Zux <04> <04> PK <00> <00>
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\ No newline at end of file
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--
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2.17.1
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