dckcandClaude Opus 5.5
f0557d29d6
The switchboard now serves a Cap'n Web Handle on each of its sockets:
public (no loopback or private addresses) and local. A socket's labels
are fixed in config, so holding the socket's fd is holding that handle;
constrain(labels) returns a narrower one, as Flower's Constrain returns
a narrower fd. Labels only accumulate: a missing key matches anything,
and a key both sides set must agree (labels.js, shared by both).
The switchboard enforces the labels; toybox's Egress no longer checks
URLs itself. It opens a session to its one switchboard socket, constrains
the handle to the vat's grant, and forwards through it; a WebSocket
crosses the session as a pair of message streams. A vat narrows its own
grant with env.egress.constrain().
Grants are now labels as JSON. One stored before, a bare host[:port],
reads as {host, port}.
pnpm start and the systemd units give toybox the public handle; the
switchboard unit binds the local one in its own 0700 runtime directory.
The tests give their toybox the local handle to reach an echo server,
and check that a toybox holding only the public one never reaches it.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
53 lines
1.6 KiB
JavaScript
53 lines
1.6 KiB
JavaScript
/**
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* @file Egress labels, after [Flower](https://github.com/NuxiNL/flower)'s
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* switchboard: string key-value pairs that only accumulate. A missing key
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* matches anything; a key present on both sides must agree.
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*
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* Keys that constrain a URL: `scheme` (`http`, `https`), `host` (name or
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* address, no port), `port` (explicit or the scheme's default). The
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* switchboard sets `network` per socket; it constrains no URL.
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*/
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const DEFAULT_PORT = { http: "80", https: "443" };
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/**
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* Union of two label sets; throws on a key they give different values,
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* naming the key but not the values (they may end up in logs).
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*
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* @param {Record<string, string>} held
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* @param {Record<string, string>} more
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*/
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export const mergeLabels = (held, more) => {
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const merged = { ...held };
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for (const [k, v] of Object.entries(more)) {
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if (typeof v !== "string") throw new TypeError(`label ${k} is not a string`);
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if (k in merged && merged[k] !== v) throw new Error(`label ${k} is already set to a different value`);
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merged[k] = v;
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}
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return Object.freeze(merged);
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};
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/**
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* The labels a URL carries.
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*
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* @param {string} url
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*/
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export const urlLabels = (url) => {
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const u = new URL(url);
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const scheme = u.protocol.replace(/:$/, "");
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return { scheme, host: u.hostname, port: u.port || DEFAULT_PORT[scheme] || "" };
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};
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/**
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* Throws unless `url` is within `labels`.
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*
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* @param {Record<string, string>} labels
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* @param {string} url
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*/
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export const checkUrl = (labels, url) => {
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const actual = urlLabels(url);
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for (const [k, v] of Object.entries(actual)) {
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if (k in labels && labels[k] !== v) throw new Error(`egress to ${actual.host} not granted`);
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}
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};
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