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punktfunk/web/nitro-entry/bun-https.mjs
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enricobuehler defdfbdb58
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fix(security): plugin UIs get their own origin
Closes H-3 of the 2026-08-05 review, the last of its six highs. A plugin's
interface was reverse-proxied onto the console's own origin and framed with
`allow-same-origin`, so plugin JS ran as first-party code on that origin: one
`fetch('/api/**', {credentials:'same-origin'})` and the BFF attached the
operator's ADMIN bearer. That reached everything `plugin_may_access` withholds
— arm pairing, read the host PIN, approve a device, read `/hooks`. The "open
in new tab" link was the same escalation with no iframe involved at all.

The fix is not a sandbox attribute, and it is worth writing down why, because
the obvious change is the one that does not work. Dropping `allow-same-origin`
gives the frame an OPAQUE origin; its subresource requests are then cross-site;
the `SameSite=Lax` session cookie stops being sent; every plugin asset 302s to
/login and the frame is blank. Nothing about the new-tab link is helped either.

So the origin moves instead. A second listener on its own port (default
PORT + 1) serves plugin UIs and nothing else:

  different ORIGIN — scheme+host+PORT — so the same-origin policy separates the
                     plugin from the console: it cannot read the console's DOM,
                     its cross-origin fetch of /api/** is unreadable (no CORS)
                     and cannot mutate (Sec-Fetch-Site sees same-site).
  same SITE        — cookie scope ignores the port and SameSite is computed on
                     the site, so the session cookie still reaches the plugin
                     listener and plugin pages keep working.

Enforcement is two refusals and both are load-bearing: the console origin
refuses /plugin-ui/**, and the plugin origin refuses everything ELSE — above
all /api/**, which would otherwise hand the admin bearer right back to plugin
JS that is now same-origin with that listener. Both are unconditional: if the
plugin port cannot be bound, plugin UIs are DISABLED and the console says so,
rather than falling back to the arrangement this exists to remove.

Two consequences that would otherwise bite in the field:

  The port has to be open. Done for the Windows netsh rule, the firewalld
  service and the ufw profile.

  A browser stores a self-signed-certificate exception per ORIGIN, including
  the port — and a certificate interstitial can never be shown inside an
  iframe, so the frame would just sit blank with nothing on screen explaining
  why. A `no-cors` probe distinguishes it (a TLS failure rejects; any HTTP
  answer, even 401, resolves) and the console renders a card linking the
  operator to open the port once in a real tab.

Also here: the health probe moved server-side to the console origin (it used
to rely on being same-origin with the plugin), the postMessage listener now
verifies `event.origin` — a real check rather than a tautology — and
plugin-kit's `postMessage(..., "*")` is documented as load-bearing, since
narrowing it to `location.origin` would now target the plugin's own origin and
silently drop every message.

Verified against a running console with a fake mgmt API and a fake plugin:
console /plugin-ui/** → 404; plugin-origin /api/v1/hooks, /, /login,
/_auth/logout → 404; plugin page loads 200 through its own origin;
unauthenticated plugin origin → 401 (not a redirect to a /login it does not
serve); a forged x-pf-listener header changes nothing on either listener; the
plugin's own Clear-Site-Data / Access-Control-Allow-Origin / Set-Cookie are
dropped by the proxy allowlist; the plugin origin's CSP names the console as
its only frame-ancestors source; and with the port squatted, ui-config reports
`unavailable`, the console still refuses /plugin-ui/**, and the console itself
keeps working.

Still wants on-glass confirmation in a real browser — the cookie and framing
behaviour is reasoned from spec, not observed.

cargo fmt --all --check clean; cargo check -p punktfunk-host --all-targets
green on Windows; web console builds and typechecks.
2026-08-05 17:50:04 +02:00

195 lines
11 KiB
JavaScript

// Custom Nitro server entry for the punktfunk web console.
//
// It is the stock Nitro `bun` preset entry
// (node_modules/nitropack/dist/presets/bun/runtime/bun.mjs) plus **TLS**, so the console is served
// over **HTTPS (HTTP/1.1 over TLS)** using the HOST's own identity cert (the cert native clients
// already pin). One trust anchor across the data plane, the management API, and this console. Wired
// in via `entry:` in vite.config.ts on top of Nitro's `bun` preset (which bundles the handler in).
//
// NOTE on HTTP/2 + HTTP/3: NOT offered here, on purpose. `Bun.serve` has no HTTP/2 server, and
// HTTP/3 (which Bun *can* do) is useless to a browser against this cert: QUIC refuses any cert error,
// and the host identity cert is a CN-only, no-SAN, self-signed cert (correct for native fingerprint
// PINNING, rejected by browsers). So browsers stay on HTTP/1.1 regardless — advertising h3 would just
// dangle an `Alt-Svc` no browser can use. Real h2/h3 would need a browser-TRUSTED, SAN-matching cert
// (a local CA installed per device) fronted by a server that speaks them (e.g. Caddy) — deliberately
// out of scope for a LAN console; TLS (no cleartext login/session) is the win.
//
// TWO LISTENERS, on purpose — see `PLUGIN ORIGIN` below.
//
// Env (set by the launchers / the systemd unit — see web.env.example):
// PUNKTFUNK_UI_TLS_CERT / _KEY PEM file paths (the host's cert.pem / key.pem). BOTH set ⇒ HTTPS.
// Unset ⇒ plain HTTP (local dev only).
// PORT / HOST standard Nitro bind (3000 / 0.0.0.0).
// PUNKTFUNK_UI_PLUGIN_PORT the plugin-UI origin's port (default: console port + 1).
import "#nitro-internal-pollyfills";
import wsAdapter from "crossws/adapters/bun";
import { useNitroApp } from "nitropack/runtime";
import { startScheduleRunner } from "nitropack/runtime/internal";
const nitroApp = useNitroApp();
const ws = import.meta._websocket
? wsAdapter(nitroApp.h3App.websocket)
: undefined;
// The socket peer, handed to the app as a trusted header.
//
// Nitro's `localFetch` (below) hands the app a SYNTHETIC request whose socket has no
// `remoteAddress`, so h3's `getRequestIP()` returns undefined *inside* the app and every
// per-peer decision collapses onto one shared bucket. That silently defeated the login
// throttle: five wrong passwords from anywhere locked out everyone, including the operator
// (and, since the update-apply route shares that budget, locked out host updates too).
// `server.requestIP(req)` is the only place the real peer is knowable, so we stamp it here.
// Any inbound copy is deleted first, so a client cannot forge it.
// Read back by `peerAddress()` in server/util/auth.ts — keep the two names in sync.
const PEER_IP_HEADER = "x-pf-peer-ip";
// PLUGIN ORIGIN — which listener a request arrived on, stamped the same unforgeable way.
//
// A plugin's UI used to be reverse-proxied onto the CONSOLE's own origin and framed with
// `allow-same-origin`, which means plugin JS ran as first-party code on the console origin: it
// could `fetch('/api/**', {credentials:'same-origin'})` and the BFF would attach the operator's
// ADMIN mgmt bearer. That reached everything `plugin_may_access` withholds — arm pairing, read the
// host PIN, approve a device, read `/hooks` — i.e. any plugin was one line of JS away from full
// operator admin (2026-08-05 review H-3). The "open in new tab" link was the same escalation with
// no iframe involved at all, so no sandbox attribute could have fixed it.
//
// The fix is to make the browser's own same-origin policy the boundary, by serving plugin UIs from
// a DIFFERENT ORIGIN: a second listener on its own port.
//
// different ORIGIN — scheme+host+PORT — so SOP applies: plugin JS cannot read the console's DOM,
// and its cross-origin `fetch` of `/api/**` is unreadable (we emit no CORS) and
// unable to mutate (the Sec-Fetch-Site guard sees `same-site`, not
// `same-origin`).
// same SITE — because a cookie's scope ignores the port, and SameSite is computed on the
// site, not the origin. So the `SameSite=Lax` session cookie still flows to the
// plugin origin, and plugin pages keep loading their assets while logged in.
//
// That combination is why this works and why the obvious alternative does not: dropping
// `allow-same-origin` gives the frame an OPAQUE origin, which makes its subresource requests
// cross-site, which stops the Lax cookie, which 302s every plugin asset to /login — a blank frame.
//
// The console listener refuses `/plugin-ui/**` and the plugin listener refuses everything else
// (server/middleware/auth.ts). Both halves matter: without the first the old path still works;
// without the second, plugin JS could call `/api/**` on its OWN origin and get the admin bearer
// attached right back.
const LISTENER_HEADER = "x-pf-listener";
// TLS from the host's identity cert (file PATHS → Bun.file, not PEM-in-env). Absent ⇒ plain HTTP.
const certPath = process.env.PUNKTFUNK_UI_TLS_CERT;
const keyPath = process.env.PUNKTFUNK_UI_TLS_KEY;
const tls =
certPath && keyPath
? { cert: Bun.file(certPath), key: Bun.file(keyPath) }
: undefined;
// Half-configured TLS is not a warning, it is a refusal.
//
// Two silent failures hide here, and both end with the operator staring at a console that looks
// fine. One path set and the other missing drops to plain HTTP — the login password then crosses
// the LAN in the clear on a server the operator believes is TLS. And PUNKTFUNK_UI_SECURE without
// TLS marks the session cookie Secure, which a browser refuses to store over http://, so login
// "succeeds" and every request after it is unauthenticated, forever.
//
// Neither state can serve a working console, so exiting is strictly better than serving a broken
// one: a supervisor logs the reason and the operator sees a stopped service instead of a subtly
// wrong one.
const secureFlag = /^(1|true)$/i.test(process.env.PUNKTFUNK_UI_SECURE ?? "");
if (Boolean(certPath) !== Boolean(keyPath)) {
console.error(
`punktfunk web console: only ${certPath ? "PUNKTFUNK_UI_TLS_CERT" : "PUNKTFUNK_UI_TLS_KEY"} is set — ` +
"TLS needs BOTH. Refusing to start rather than serve the login password in the clear.",
);
process.exit(1);
}
if (!tls && secureFlag) {
console.error(
"punktfunk web console: PUNKTFUNK_UI_SECURE is set but TLS is not configured. The session " +
"cookie would be marked Secure and dropped by the browser over http://, so login could " +
"never stick. Refusing to start — set PUNKTFUNK_UI_TLS_CERT/_KEY, or unset PUNKTFUNK_UI_SECURE.",
);
process.exit(1);
}
/** The shared `Bun.serve` options both listeners use — only the port and the stamped lane differ. */
const listenerOptions = (lane) => ({
host: process.env.NITRO_HOST || process.env.HOST,
// Bun defaults this to 10 s, which is SHORTER than the host's 15 s SSE keep-alive comment — so a
// proxied `/api/v1/events` stream (or any other quiet long-lived response) gets cut by us and
// reconnects on a loop. 120 s is comfortably above any keep-alive we forward; still overridable.
idleTimeout: Number.parseInt(process.env.NITRO_BUN_IDLE_TIMEOUT, 10) || 120,
// Cap the request body an UNAUTHENTICATED peer can make us hold in memory.
//
// `fetch` below buffers the whole body with `await req.arrayBuffer()` before Nitro — and
// therefore before the auth gate — has seen the request, so Bun's 128 MB default was the only
// bound on what a LAN peer could push into console RSS by POSTing to /login (2026-08-05 review
// L-10). Nothing the console legitimately accepts is remotely this large: the biggest real body
// is a hooks/library JSON edit, kilobytes. 4 MiB leaves several orders of headroom and still
// makes the memory cost of an unauthenticated request negligible.
maxRequestBodySize:
Number.parseInt(process.env.NITRO_BUN_MAX_BODY_BYTES, 10) || 4 * 1024 * 1024,
// `tls: undefined` ⇒ plain HTTP (dev); otherwise HTTPS over HTTP/1.1.
tls,
websocket: import.meta._websocket ? ws.websocket : undefined,
async fetch(req, server) {
if (import.meta._websocket && req.headers.get("upgrade") === "websocket") {
return ws.handleUpgrade(req, server);
}
const url = new URL(req.url);
let body;
if (req.body) {
body = await req.arrayBuffer();
}
// Strip any client-supplied value BEFORE stamping the real one (see PEER_IP_HEADER).
const headers = new Headers(req.headers);
headers.delete(PEER_IP_HEADER);
headers.delete(LISTENER_HEADER);
const peer = server.requestIP(req)?.address;
if (peer) headers.set(PEER_IP_HEADER, peer);
headers.set(LISTENER_HEADER, lane);
return nitroApp.localFetch(url.pathname + url.search, {
host: url.hostname,
protocol: url.protocol,
headers,
method: req.method,
redirect: req.redirect,
body,
});
},
});
const consolePort = Number(process.env.NITRO_PORT || process.env.PORT || 3000);
const server = Bun.serve({ ...listenerOptions("console"), port: consolePort });
console.log(`punktfunk web console listening on ${server.url} (tls=${!!tls})`);
// The plugin-UI origin. Its own port, everything else identical.
//
// A bind failure does NOT fall back to serving plugin UIs on the console origin — that is the hole
// this exists to close, and a security boundary that disappears when a port is busy is not one. It
// degrades to "plugin UIs unavailable": the console reads the state below and renders an
// explanation instead of a frame, and everything else about the console keeps working.
const pluginPort = Number(process.env.PUNKTFUNK_UI_PLUGIN_PORT || consolePort + 1);
let pluginServer;
try {
pluginServer = Bun.serve({ ...listenerOptions("plugin"), port: pluginPort });
// Read back by the app (server/util/pluginOrigin.ts) — same process, so process.env is the
// simplest channel, and it is only ever SET here, never trusted from the environment we started
// with (a stale inherited value would otherwise advertise a port nothing is listening on).
process.env.PUNKTFUNK_UI_PLUGIN_PORT_ACTIVE = String(pluginPort);
process.env.PUNKTFUNK_UI_CONSOLE_PORT_ACTIVE = String(consolePort);
console.log(
`punktfunk plugin-UI origin listening on ${pluginServer.url} (tls=${!!tls})`,
);
} catch (e) {
delete process.env.PUNKTFUNK_UI_PLUGIN_PORT_ACTIVE;
console.error(
`punktfunk web console: could not bind the plugin-UI origin on port ${pluginPort} ` +
`(${e?.message ?? e}). Plugin UIs are DISABLED until this is resolved — they are ` +
"deliberately not served on the console's own origin, because a plugin sharing that " +
"origin can act as the logged-in operator. Set PUNKTFUNK_UI_PLUGIN_PORT to a free port.",
);
}
if (import.meta._tasks) {
startScheduleRunner();
}