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fix: improve WAR extraction in Util.explodeWar #746

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fix: improve WAR extraction in Util.explodeWar #746

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36 changes: 20 additions & 16 deletions bootstrap/src/main/java/io/jenkins/jenkinsfile/runner/bootstrap/Util.java
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Original file line number Diff line number Diff line change
Expand Up @@ -5,12 +5,12 @@
import picocli.CommandLine;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardCopyOption;
import java.util.Enumeration;
import java.util.Properties;
import java.util.jar.JarEntry;
Expand Down Expand Up @@ -67,30 +67,34 @@ public static File explodeWar(File warFile) throws IOException {
// Get current working directory path
Path currentPath = FileSystems.getDefault().getPath("").toAbsolutePath();
//Create Temporary directory
Path path = Files.createTempDirectory(currentPath.toAbsolutePath(), "jenkinsfile-runner");
File destDir = path.toFile();
Path destPath = Files.createTempDirectory(currentPath.toAbsolutePath(), "jenkinsfile-runner");
File destDir = destPath.toFile();
// Canonicalize once so every entry can be checked against the real destination root,
// guarding against a maliciously crafted WAR escaping it via "../" or absolute paths
// (a.k.a. "Zip Slip", CWE-22).
Path destDirReal = destPath.toRealPath();

while (enu.hasMoreElements()) {
JarEntry je = enu.nextElement();
File file = new File(destDir, je.getName());
if (!file.exists()) {
file.getParentFile().mkdirs();
file = new File(destDir, je.getName());

Path resolved = destDirReal.resolve(je.getName()).normalize();
if (!resolved.startsWith(destDirReal)) {
throw new IOException(
"Entry " + je.getName() + " in " + warFile
+ " would be extracted outside of the target directory. Aborting.");
}

if (je.isDirectory()) {
Files.createDirectories(resolved);
continue;
}
InputStream is = jarfile.getInputStream(je);

try (FileOutputStream fo = new FileOutputStream(file)) {
while (is.available() > 0) {
fo.write(is.read());
}
fo.close();
is.close();

Files.createDirectories(resolved.getParent());
try (InputStream is = jarfile.getInputStream(je)) {
Files.copy(is, resolved, StandardCopyOption.REPLACE_EXISTING);
}
}
return destDir;
}
}
}
}