vuln-fix: Partial Path Traversal Vulnerability

This fixes a partial path traversal vulnerability.

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())`.

To demonstrate this vulnerability, 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: Medium
CVSSS: 6.1
Detection: CodeQL & OpenRewrite (https://public.moderne.io/recipes/org.openrewrite.java.security.PartialPathTraversalVulnerability)

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

Bug-tracker: JLLeitschuh/security-research#13

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

Author: JLLeitschuh

bigdata-core/bigdata/src/java/com/bigdata/resources/ResourceFileFilter.java

@@ -3,6 +3,7 @@
 import java.io.File;
 import java.io.FileFilter;
 import java.io.IOException;
+import java.nio.file.Paths;
 
 import org.apache.log4j.Logger;
 
@@ -82,7 +83,7 @@ final public boolean accept(File f) {
 
             }
 
-            if (!fc.startsWith(resourceManager.getDataDir().getPath())) {
+            if (!Paths.get(fc).normalize().startsWith(resourceManager.getDataDir().getPath())) {
 
                 throw new RuntimeException("File not in data directory: file="
                         + f + ", dataDir=" + resourceManager.dataDir);