Merge pull request #629 from pbakaus/fix/618-live-source-symlink

Fix: stop live-server /source from following symlinks out of the workspace (#618)

skill/scripts/live-server.mjs

@@ -936,15 +936,23 @@ function createRequestHandler({ detectScript, liveScriptParts }) {
       const filePath = url.searchParams.get('path');
       if (!filePath || filePath.includes('..')) { res.writeHead(400); res.end('Bad path'); return; }
       const absPath = path.resolve(process.cwd(), filePath);
-      // Confine to the project root. A bare `startsWith(cwd)` string check lets a
-      // sibling dir whose name extends the root name (projeto -> projeto-backup)
-      // slip through; compare on the relative path instead (same pattern as
-      // sessionFileMetadataFromPollReply below). An empty rel means the request
-      // resolved to the root directory itself, which this file route never serves.
-      const rel = path.relative(process.cwd(), absPath);
+      let realRoot, realTarget;
+      try {
+        realRoot = fs.realpathSync(process.cwd());
+        realTarget = fs.realpathSync(absPath);
+      } catch {
+        res.writeHead(404); res.end('File not found'); return;
+      }
+      // Confine to the project root after symlink resolution. A bare
+      // `startsWith(cwd)` string check lets a sibling dir whose name extends the
+      // root name (projeto -> projeto-backup) slip through; compare on the
+      // relative path instead (same pattern as sessionFileMetadataFromPollReply
+      // below). An empty rel means the request resolved to the root directory
+      // itself, which this file route never serves.
+      const rel = path.relative(realRoot, realTarget);
       if (!rel || rel.startsWith('..') || path.isAbsolute(rel)) { res.writeHead(403); res.end('Forbidden'); return; }
       let content;
-      try { content = fs.readFileSync(absPath, 'utf-8'); }
+      try { content = fs.readFileSync(realTarget, 'utf-8'); }
       catch { res.writeHead(404); res.end('File not found'); return; }
       res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8' });
       res.end(content);

tests/live-server.test.mjs

@@ -5,8 +5,8 @@
 
 import { describe, it, before, after } from 'node:test';
 import assert from 'node:assert/strict';
-import { existsSync, mkdtempSync, readFileSync, writeFileSync, mkdirSync, rmSync, realpathSync } from 'node:fs';
-import { join } from 'node:path';
+import { existsSync, mkdtempSync, readFileSync, writeFileSync, mkdirSync, rmSync, realpathSync, symlinkSync } from 'node:fs';
+import { join, relative } from 'node:path';
 import { tmpdir } from 'node:os';
 import { execFileSync, execSync, spawn } from 'node:child_process';
 import {
@@ -3319,6 +3319,102 @@ colors: {}
     }
   });
 
+  it('/source rejects a symlink that points outside the project root', async () => {
+    const outsideDir = mkdtempSync(join(tmpdir(), 'impeccable-live-outside-'));
+    const outsideFile = join(outsideDir, 'secret.txt');
+    writeFileSync(outsideFile, 'OUTSIDE SECRET');
+    const linkPath = join(serverCwd, 'linked.txt');
+    symlinkSync(outsideFile, linkPath);
+    try {
+      const res = await fetch(`http://localhost:${server.port}/source?token=${server.token}&path=linked.txt`);
+      await res.text().catch(() => {});
+      assert.equal(res.status, 403);
+    } finally {
+      rmSync(linkPath, { force: true });
+      rmSync(outsideDir, { recursive: true, force: true });
+    }
+  });
+
+  it('/source serves a symlink whose target stays inside the project', async () => {
+    const nestedDir = join(serverCwd, 'alias');
+    mkdirSync(nestedDir, { recursive: true });
+    const realFile = join(nestedDir, 'page.html');
+    writeFileSync(realFile, '<h1>via alias</h1>\n');
+    const linkPath = join(serverCwd, 'alias-link.html');
+    symlinkSync(realFile, linkPath);
+    try {
+      const res = await fetch(`http://localhost:${server.port}/source?token=${server.token}&path=alias-link.html`);
+      assert.equal(res.status, 200);
+      const text = await res.text();
+      assert.ok(text.includes('via alias'));
+    } finally {
+      rmSync(linkPath, { force: true });
+      rmSync(nestedDir, { recursive: true, force: true });
+    }
+  });
+
+  it('/source returns 404 for a broken symlink', async () => {
+    const linkPath = join(serverCwd, 'broken-link.txt');
+    symlinkSync(join(serverCwd, 'missing-target.txt'), linkPath);
+    try {
+      const res = await fetch(`http://localhost:${server.port}/source?token=${server.token}&path=broken-link.txt`);
+      await res.text().catch(() => {});
+      assert.equal(res.status, 404);
+    } finally {
+      rmSync(linkPath, { force: true });
+    }
+  });
+
+  it('/source rejects a directory symlink whose nested file is outside the project', async () => {
+    const outsideDir = mkdtempSync(join(tmpdir(), 'impeccable-live-outside-dir-'));
+    writeFileSync(join(outsideDir, 'cred.txt'), 'OUTSIDE SECRET');
+    const linkPath = join(serverCwd, 'escape-dir');
+    symlinkSync(outsideDir, linkPath);
+    try {
+      const res = await fetch(`http://localhost:${server.port}/source?token=${server.token}&path=escape-dir/cred.txt`);
+      await res.text().catch(() => {});
+      assert.equal(res.status, 403);
+    } finally {
+      rmSync(linkPath, { force: true });
+      rmSync(outsideDir, { recursive: true, force: true });
+    }
+  });
+
+  it('/source rejects a chained symlink that resolves outside the project', async () => {
+    const outsideDir = mkdtempSync(join(tmpdir(), 'impeccable-live-outside-chain-'));
+    const outsideFile = join(outsideDir, 'secret.txt');
+    writeFileSync(outsideFile, 'OUTSIDE SECRET');
+    const midPath = join(serverCwd, 'mid-link.txt');
+    const linkPath = join(serverCwd, 'double-out.txt');
+    symlinkSync(outsideFile, midPath);
+    symlinkSync(midPath, linkPath);
+    try {
+      const res = await fetch(`http://localhost:${server.port}/source?token=${server.token}&path=double-out.txt`);
+      await res.text().catch(() => {});
+      assert.equal(res.status, 403);
+    } finally {
+      rmSync(linkPath, { force: true });
+      rmSync(midPath, { force: true });
+      rmSync(outsideDir, { recursive: true, force: true });
+    }
+  });
+
+  it('/source rejects a relative symlink that points outside the project', async () => {
+    const outsideDir = mkdtempSync(join(tmpdir(), 'impeccable-live-outside-rel-'));
+    const outsideFile = join(outsideDir, 'secret.txt');
+    writeFileSync(outsideFile, 'OUTSIDE SECRET');
+    const linkPath = join(serverCwd, 'rel-out.txt');
+    symlinkSync(relative(serverCwd, outsideFile), linkPath);
+    try {
+      const res = await fetch(`http://localhost:${server.port}/source?token=${server.token}&path=rel-out.txt`);
+      await res.text().catch(() => {});
+      assert.equal(res.status, 403);
+    } finally {
+      rmSync(linkPath, { force: true });
+      rmSync(outsideDir, { recursive: true, force: true });
+    }
+  });
+
   it('/modern-screenshot.js serves the vendored UMD build', async () => {
     const res = await fetch(`http://localhost:${server.port}/modern-screenshot.js`);
     assert.equal(res.status, 200);