Merge pull request #23627 from vespa-engine/mortent/path-validation

Path validation

2 files changed, 71 insertions, 0 deletions

diff --git a/vespajlib/src/main/java/ai/vespa/validation/PathValidator.java b/vespajlib/src/main/java/ai/vespa/validation/PathValidator.java
new file mode 100644
index 00000000000..0ae81e2315d
--- /dev/null
+++ b/vespajlib/src/main/java/ai/vespa/validation/PathValidator.java
@@ -0,0 +1,36 @@
+package ai.vespa.validation;
+
+import java.nio.file.Path;
+
+/**
+ * Path validations
+ *
+ * @author mortent
+ */
+public class PathValidator {
+
+    /**
+     * Validate that file is a child of basedir
+     * @param root Root directory to use for validation
+     * @param path Path to validate
+     * @throws IllegalArgumentException if path is not a child of root
+     */
+    public static void validateChildOf(Path root, Path path) {
+        if (!path.normalize().startsWith(root)) {
+            throw new IllegalArgumentException("Invalid path %s".formatted(path));
+        }
+    }
+
+    /**
+     * Resolves a path under a root path
+     * @param root root poth
+     * @param path child to resolve
+     * @return The resolved path
+     * @throws IllegalArgumentException If the provided child path does not resolve as child of root
+     */
+    public static Path resolveChildOf(Path root, String path) {
+        Path resolved = root.resolve(path);
+        validateChildOf(root, resolved);
+        return resolved;
+    }
+}
diff --git a/vespajlib/src/test/java/ai/vespa/validation/PathValidatorTest.java b/vespajlib/src/test/java/ai/vespa/validation/PathValidatorTest.java
new file mode 100644
index 00000000000..a2c1bd6bd0c
--- /dev/null
+++ b/vespajlib/src/test/java/ai/vespa/validation/PathValidatorTest.java
@@ -0,0 +1,35 @@
+package ai.vespa.validation;
+
+import org.junit.Test;
+
+import java.nio.file.Path;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class PathValidatorTest {
+
+    @Test
+    public void testPathValidation() {
+        Path root = Path.of("/foo/");
+
+        assertOk(Path.of("/foo/bar"), root);
+        assertOk(Path.of("/foo/foo2/bar"), root);
+        assertOk(Path.of("/foo/foo2/../bar"), root);
+        assertOk(Path.of("/foo/../foo/bar"), root);
+        assertOk(Path.of("/bar/../foo/../foo/bar"), root);
+
+        assertInvalid(Path.of("/foo/../bar"), root);
+        assertInvalid(Path.of("/foo/bar/../../bar"), root);
+    }
+
+    private void assertOk(Path path, Path root) {
+        PathValidator.validateChildOf(root, path);
+    }
+
+    private void assertInvalid(Path path, Path root) {
+        IllegalArgumentException illegalArgumentException = assertThrows(IllegalArgumentException.class,
+                                                                         () -> PathValidator.validateChildOf(root, path));
+        assertEquals("Invalid path %s".formatted(path), illegalArgumentException.getMessage());
+    }
+}