vuln-fix: Zip Slip Vulnerability

This fixes a Zip-Slip vulnerability.

This change does one of two things. This change either

1. Inserts a guard to protect against Zip Slip.
OR
2. Replaces `dir.getCanonicalPath().startsWith(parent.getCanonicalPath())`, which is vulnerable to partial path traversal attacks, with the more secure `dir.getCanonicalFile().toPath().startsWith(parent.getCanonicalFile().toPath())`.

For number 2, consider `"/usr/outnot".startsWith("/usr/out")`.
The check is bypassed although `/outnot` is not under the `/out` directory.
It's important to understand that the terminating slash may be removed when using various `String` representations of the `File` object.
For example, on Linux, `println(new File("/var"))` will print `/var`, but `println(new File("/var", "/")` will print `/var/`;
however, `println(new File("/var", "/").getCanonicalPath())` will print `/var`.

Weakness: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Severity: High
CVSSS: 7.4
Detection: CodeQL (https://codeql.github.com/codeql-query-help/java/java-zipslip/) & OpenRewrite (https://public.moderne.io/recipes/org.openrewrite.java.security.ZipSlip)

Reported-by: Jonathan Leitschuh <[email protected]>
Signed-off-by: Jonathan Leitschuh <[email protected]>

Bug-tracker: JLLeitschuh/security-research#16


Co-authored-by: Moderne <[email protected]>

Author: JLLeitschuh

src/test/java/com/conveyal/datatools/manager/jobs/DeploymentGisExportJobTest.java

@@ -33,6 +33,9 @@ private File[] getFoldersFromZippedShapefile(File zipFile) throws IOException {
         while (e.hasMoreElements()) {
             ZipEntry entry = e.nextElement();
             File destinationPath = new File(destDir, entry.getName());
+            if (!destinationPath.toPath().normalize().startsWith(destDir.toPath())) {
+                throw new RuntimeException("Bad zip entry");
+            }
             // Create parent directories
             destinationPath.getParentFile().mkdirs();
 
@@ -120,4 +123,4 @@ public void canExportRoutes() throws IOException, SQLException {
     @Test
     public void canExportRoutesFromPatternStops() {}
 
-}
+}

src/test/java/com/conveyal/datatools/manager/jobs/GisExportJobTest.java

@@ -265,6 +265,9 @@ public File[] getFilesFromZippedShapefile(File zipFile) throws IOException {
         ZipEntry zipEntry = zis.getNextEntry();
         while (zipEntry != null) {
             File newFile = new File(destDir, zipEntry.getName());
+            if (!newFile.toPath().normalize().startsWith(destDir.toPath())) {
+                throw new RuntimeException("Bad zip entry");
+            }
             FileOutputStream fos = new FileOutputStream(newFile);
             int len;
             while ((len = zis.read(buffer)) > 0) {