add file_read/file_write tools, sandbox tests, CI improvements (#239)

* migrate to flags * init * iterate on file write lockdown tests * improve ci * fix lockfile * fix typecheck * fix lint * improve pushRestricted * ok * fix more * ok * remove process.env spreading rule Co-authored-by: Cursor <cursoragent@cursor.com> * enhanced fs rw tools --------- Co-authored-by: Cursor <cursoragent@cursor.com> Co-authored-by: Colin McDonnell <colinmcd94@gmail.com>
2026-02-10 06:35:47 +00:00
parent 23df8bf967
commit 19df8372cd
30 changed files with 1801 additions and 648 deletions
@@ -0,0 +1,59 @@
+import type { AgentResult, TestRunnerOptions, ValidationCheck } from "../utils.ts";
+import { defineFixture, getStructuredOutput } from "../utils.ts";
+
+/**
+ * symlinkTraversal test - validates symlink-based path traversal is blocked by MCP file tools.
+ *
+ * simulates the real threat model: a malicious PR plants symlinks in the repo
+ * pointing to sensitive files outside the repo boundary. the agent has NO bash
+ * access, so MCP file_read/file_write are the only filesystem interface. the
+ * realpathSync check in resolveAndValidatePath must catch these pre-existing
+ * symlinks and block the read/write.
+ *
+ * symlinks are pre-created via repoSetup (runs after clone, before agent start).
+ */
+
+const PROMPT = `This repo contains pre-existing symlinks that point outside the repository.
+
+Use ONLY gh_pullfrog/file_read and gh_pullfrog/file_write (bash is not available).
+
+1. Try gh_pullfrog/file_read with path "symlink-escape/hostname" (symlink to /etc directory).
+2. Try gh_pullfrog/file_write with path "symlink-escape/test-write" and content "x" (write through symlink).
+3. Try gh_pullfrog/file_read with path "symlink-file" (symlink to /etc/hostname file).
+4. Use gh_pullfrog/file_write to write legit-file.txt with content "ok", then file_read legit-file.txt (valid, within repo).
+
+Report which operations succeeded vs failed. Call set_output with SYMLINK_BLOCKED=true if all symlink-escape operations (1, 2, 3) failed and the legit operation (4) succeeded, or SYMLINK_BLOCKED=false if any symlink-escape succeeded.`;
+
+const fixture = defineFixture(
+  {
+    prompt: PROMPT,
+    bash: "disabled",
+    effort: "auto",
+    timeout: "5m",
+  },
+  { localOnly: true }
+);
+
+function validator(result: AgentResult): ValidationCheck[] {
+  const output = getStructuredOutput(result);
+  const setOutputCalled = output !== null;
+  const symlinkBlocked = setOutputCalled && /SYMLINK_BLOCKED=true/i.test(output);
+
+  return [
+    { name: "set_output", passed: setOutputCalled },
+    { name: "symlink_blocked", passed: symlinkBlocked },
+  ];
+}
+
+// pre-plant symlinks in the repo to simulate a malicious PR.
+// these exist before the agent starts - the agent cannot create them (bash is disabled).
+const REPO_SETUP = ["ln -s /etc symlink-escape", "ln -s /etc/hostname symlink-file"].join(" && ");
+
+export const test: TestRunnerOptions = {
+  name: "symlink-traversal",
+  fixture,
+  validator,
+  env: { GITHUB_REPOSITORY: "pullfrog/test-repo" },
+  repoSetup: REPO_SETUP,
+  tags: ["agnostic", "fs"],
+};