57 lines
2.9 KiB
TypeScript
57 lines
2.9 KiB
TypeScript
// Optional revocation denylist (todo §9): instant role/session revoke without putting Keto
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// back on the hot path. Off by default — enable with REVOCATION_DENYLIST=true.
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//
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// The hot path verifies a short-lived (~10m) session JWT in-process, so a revoked role or a
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// killed session only takes effect when the token is next minted (re-login / TTL refresh) —
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// up to one token TTL of lag. For security-critical revoke (offboarding, a compromised
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// account) that lag is too long. An admin action records the subject as revoked-now and the
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// hot path then rejects that subject's pre-revoke tokens at once, forcing a re-mint (which
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// re-reads roles from Keto, or clears a now-dead session).
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//
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// Cost & scope: an in-memory, auto-evicting Map — no database, like the JWKS cache, so it
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// stays inside the stateless model. A token carries `iat`, so a *fresh* re-login (iat after
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// the revoke) passes while every token minted before the revoke is rejected. Entries self-evict
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// after one token TTL, by which point any pre-revoke token has expired anyway. Single-process:
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// instant on the instance that handled the revoke; across replicas/restarts the guarantee
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// falls back to the token TTL (the gap is just no longer closed early). Back it with a shared
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// store for hard multi-instance instant-revoke.
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export interface Denylist {
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// Hot-path check: is a token for `sub`, issued at `iat` (unix sec), revoked? A token minted
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// after the latest revoke passes (a fresh re-login); a missing `iat` fails closed.
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isRevoked(sub: string, iat: number | undefined): boolean;
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// Record `sub` (a Kratos identity id) as revoked as of now: every token for it minted at or
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// before this instant is rejected until it would have expired anyway.
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revoke(sub: string): void;
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}
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export interface DenylistOptions {
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now?: () => number; // unix seconds; injectable for tests
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ttlSec?: number; // entry lifetime; keep ≥ tokenizer TTL + clock skew (default 900 ≥ 10m + 60s)
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}
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export function createDenylist(options: DenylistOptions = {}): Denylist {
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const ttl = options.ttlSec ?? 900;
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const clock = options.now ?? (() => Math.floor(Date.now() / 1000));
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const revokedAt = new Map<string, number>(); // sub → unix sec of its latest revoke
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return {
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isRevoked(sub, iat) {
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const at = revokedAt.get(sub);
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if (at === undefined) return false;
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if (clock() - at > ttl) {
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revokedAt.delete(sub); // expired entry — any token it could match is long gone
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return false;
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}
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return iat === undefined || iat <= at; // pre-revoke token (or unknown iat) ⇒ revoked
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},
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revoke(sub) {
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const now = clock();
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// Full-scan prune (cheap, and only on a revoke — never the hot path) keeps the map bounded
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// to recently-revoked subjects.
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for (const [s, at] of revokedAt) if (now - at > ttl) revokedAt.delete(s);
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revokedAt.set(sub, now); // latest revoke wins; advances the cutoff
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},
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};
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}
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