Fix low-level security issues

Content-Security-Policy: add header with default-src 'self',
unsafe-inline for styles (needed for JS-generated inline style attrs),
and data: for embedded logo/signature images.

JSON body limit: reduce from 10mb to 2mb (logo cap is 512KB base64).

Session maxAge: now configurable via SESSION_MAX_AGE_HOURS env var
(default 168h / 7 days). Documented in .env.example.

Password strength: centralize validation in auth.js and raise the bar
to 10+ characters with at least one letter and one non-letter. Applied
consistently to all four password-setting paths (initial setup,
login change-password, admin create user, admin edit user).

.env.example

@@ -2,5 +2,6 @@
 # Generate SESSION_SECRET with: openssl rand -hex 32
 
 SESSION_SECRET=replace-with-a-random-64-character-hex-string
+SESSION_MAX_AGE_HOURS=168   # default: 168 (7 days)
 PORT=3000
 DB_PATH=/app/data/check-printing.db

src/app.js

@@ -25,12 +25,14 @@ if (!process.env.SESSION_SECRET && process.env.NODE_ENV === 'production') {
 const SESSION_SECRET = process.env.SESSION_SECRET ||
   (() => { console.warn('[warn] SESSION_SECRET not set — using random secret (sessions will reset on restart)'); return crypto.randomBytes(32).toString('hex'); })();
 
+const SESSION_MAX_AGE_MS = (parseInt(process.env.SESSION_MAX_AGE_HOURS, 10) || 168) * 60 * 60 * 1000;
+
 app.use(session({
   store: new SessionStore(db),
   secret: SESSION_SECRET,
   resave: false,
   saveUninitialized: false,
-  cookie: { httpOnly: true, sameSite: 'strict', maxAge: 7 * 24 * 60 * 60 * 1000 }, // 7 days
+  cookie: { httpOnly: true, sameSite: 'strict', maxAge: SESSION_MAX_AGE_MS },
 }));
 
 // Security headers
@@ -38,10 +40,14 @@ app.use((req, res, next) => {
   res.setHeader('X-Content-Type-Options', 'nosniff');
   res.setHeader('X-Frame-Options', 'DENY');
   res.setHeader('Referrer-Policy', 'same-origin');
+  // style-src unsafe-inline: required for inline style= attrs in JS-generated HTML
+  // img-src data: required for base64-embedded logos and signatures
+  res.setHeader('Content-Security-Policy',
+    "default-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; object-src 'none'");
   next();
 });
 
-app.use(express.json({ limit: '10mb' }));
+app.use(express.json({ limit: '2mb' }));
 app.use(express.static(path.join(__dirname, '../public')));
 
 // ── Auth routes (public — no requireAuth) ─────────────────────────────────────

src/routes/auth.js

@@ -5,6 +5,15 @@ const router  = express.Router();
 const bcrypt  = require('bcryptjs');
 const db      = require('../db/database');
 
+// ── Password validation ───────────────────────────────────────────────────────
+// Returns an error string if invalid, or null if acceptable.
+function validatePassword(password) {
+  if (!password || password.length < 10) return 'Password must be at least 10 characters.';
+  if (!/[a-zA-Z]/.test(password))        return 'Password must contain at least one letter.';
+  if (!/[^a-zA-Z]/.test(password))       return 'Password must contain at least one digit or symbol.';
+  return null;
+}
+
 // ── Login rate limiter ────────────────────────────────────────────────────────
 // Tracks failed login attempts per IP. After 10 failures within 15 minutes,
 // further attempts are blocked until the window resets.
@@ -57,7 +66,8 @@ router.post('/setup', async (req, res) => {
 
   const { username, password } = req.body;
   if (!username || !password) return res.status(400).json({ error: 'Username and password required.' });
-  if (password.length < 8) return res.status(400).json({ error: 'Password must be at least 8 characters.' });
+  const pwErr = validatePassword(password);
+  if (pwErr) return res.status(400).json({ error: pwErr });
 
   const hash = await bcrypt.hash(password, 12);
   const result = db.prepare(
@@ -121,7 +131,8 @@ router.post('/change-password', async (req, res) => {
 
   const { current_password, new_password } = req.body;
   if (!current_password || !new_password) return res.status(400).json({ error: 'Both fields required.' });
-  if (new_password.length < 8) return res.status(400).json({ error: 'New password must be at least 8 characters.' });
+  const pwErr = validatePassword(new_password);
+  if (pwErr) return res.status(400).json({ error: pwErr });
 
   const user = db.prepare('SELECT * FROM users WHERE id = ?').get(req.session.userId);
   const match = await bcrypt.compare(current_password, user.password_hash);
@@ -135,3 +146,4 @@ router.post('/change-password', async (req, res) => {
 });
 
 module.exports = router;
+module.exports.validatePassword = validatePassword;

src/routes/users.js

@@ -5,6 +5,7 @@ const router  = express.Router();
 const bcrypt  = require('bcryptjs');
 const db      = require('../db/database');
 const { requireAuth, requireAdmin } = require('../middleware/auth');
+const { validatePassword } = require('./auth');
 
 // All /api/users routes require admin
 router.use(requireAuth, requireAdmin);
@@ -30,7 +31,8 @@ router.post('/', async (req, res) => {
   const { username, password, role, accounts } = req.body;
   if (!username || !password) return res.status(400).json({ error: 'Username and password required.' });
   if (!['admin', 'editor', 'viewer'].includes(role)) return res.status(400).json({ error: 'Invalid role.' });
-  if (password.length < 8) return res.status(400).json({ error: 'Password must be at least 8 characters.' });
+  const pwErr = validatePassword(password);
+  if (pwErr) return res.status(400).json({ error: pwErr });
 
   const hash = await bcrypt.hash(password, 12);
 
@@ -80,7 +82,8 @@ router.put('/:id', async (req, res) => {
   }
 
   if (password) {
-    if (password.length < 8) return res.status(400).json({ error: 'Password must be at least 8 characters.' });
+    const pwErr = validatePassword(password);
+    if (pwErr) return res.status(400).json({ error: pwErr });
     const hash = await bcrypt.hash(password, 12);
     db.prepare("UPDATE users SET password_hash = ?, updated_at = datetime('now') WHERE id = ?")
       .run(hash, req.params.id);