Golang: Mark filepath.IsLocal as a tainted-path sanitizer guard

[smowton]

No description provided.

[Copilot]

Pull Request Overview

This pull request adds support for recognizing filepath.IsLocal() as a path traversal sanitizer in the Go security analysis. The change treats calls to this function as a security guard that can prevent path traversal attacks when the function returns true.

• Adds a new IsLocalCheck sanitizer guard class to recognize filepath.IsLocal() calls
• Updates test cases to include an example of the sanitized path usage pattern

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
go/ql/lib/semmle/go/security/TaintedPathCustomizations.qll	Implements the IsLocalCheck class to treat filepath.IsLocal() as a tainted-path sanitizer guard
go/ql/test/query-tests/Security/CWE-022/TaintedPath.go	Adds test case demonstrating proper usage of filepath.IsLocal() as a security check

[Copilot]

The filepath.IsLocal() check alone may not provide complete path traversal protection. Consider combining it with additional validation such as filepath.Clean() or checking against an allowlist of permitted directories, as IsLocal() only validates that the path doesn't escape the current directory but doesn't prevent access to sensitive files within it.

Suggested change

	if filepath.IsLocal(tainted_path) {
	data, _ = ioutil.ReadFile(tainted_path)
	cleanedPath := filepath.Clean(tainted_path)
	allowedDir := "/allowed/directory" // Replace with the actual allowed directory
	if filepath.IsLocal(cleanedPath) && strings.HasPrefix(cleanedPath, allowedDir) {
	data, _ = ioutil.ReadFile(cleanedPath)