🛡️ Sentinel: [HIGH] Fix path traversal in file download/read

.jules/sentinel.md

@@ -0,0 +1,4 @@
+## 2025-04-02 - Path Traversal in File Validation
+**Vulnerability:** Path traversal vulnerability in `StatusSocket.swift`'s `validate_config` socket command.
+**Learning:** `expandingTildeInPath` does not resolve `..` or sandbox the path, allowing a malicious user to access files outside the user's home directory.
+**Prevention:** Use `.standardizingPath` after `.expandingTildeInPath`, and enforce directory boundaries by verifying the final path `.hasPrefix()` against a canonical allowed path, such as the user's home directory.

Sources/Cacheout/Headless/StatusSocket.swift

@@ -474,14 +474,26 @@ public final class StatusSocket: @unchecked Sendable {
         }
 
         let expandedPath = (path as NSString).expandingTildeInPath
+        let standardizedPath = (expandedPath as NSString).standardizingPath
+
+        let allowedPrefix = URL(fileURLWithPath: FileManager.default.homeDirectoryForCurrentUser.path)
+            .appendingPathComponent(".cacheout").path + "/"
+
+        guard standardizedPath.hasPrefix(allowedPrefix) else {
+            sendSuccessResponse(fd: fd, data: [
+                "valid": false,
+                "errors": ["Path traversal detected or path outside allowed directory: \(standardizedPath)"],
+            ] as [String: Any])
+            return
+        }
 
         // lstat to reject symlinks to special files, FIFOs, devices, etc.
         var sb = Darwin.stat()
-        let statResult: Int32 = lstat(expandedPath, &sb)
+        let statResult: Int32 = lstat(standardizedPath, &sb)
         guard statResult == 0 else {
             sendSuccessResponse(fd: fd, data: [
                 "valid": false,
-                "errors": ["File not found: \(expandedPath)"],
+                "errors": ["File not found: \(standardizedPath)"],
             ] as [String: Any])
             return
         }
@@ -490,7 +502,7 @@ public final class StatusSocket: @unchecked Sendable {
         guard (sb.st_mode & S_IFMT) == S_IFREG else {
             sendSuccessResponse(fd: fd, data: [
                 "valid": false,
-                "errors": ["Not a regular file: \(expandedPath)"],
+                "errors": ["Not a regular file: \(standardizedPath)"],
             ] as [String: Any])
             return
         }