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parking_solution/wiki/entities/local-jwt-auth.md
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julian ef0ecadff9 fix(auth): block privilege escalation via role/user management
The dynamic-RBAC management routes are themselves grantable (role:* and
user:*), so a non-admin holding them could self-escalate: edit their own
role to add a permission they lack, mint a privileged role, assign someone
the admin role, or reset/delete a more-privileged account. Found by the
commit security review (2× HIGH).

Fix — enforce the RBAC invariant "you cannot grant beyond yourself":
- roles.ts: role:create/update reject any permission not held by the caller
  (escalates()). An admin holds the full set, so it stays unrestricted.
- users.ts: user:create/update reject assigning a role whose permissions
  exceed the caller's; update/password-reset/delete reject acting on a user
  whose current role exceeds the caller's (exceedsCaller()).

The existing no-lockout + builtin-admin protections are unchanged.

Verified: 10-assertion inject test — manager (role:* + user:* but no
tariff:update, not admin) gets 403 on self-grant, minting a privileged role,
assigning/resetting/deleting an admin; admin stays unrestricted; the manager
can still create peers + in-scope roles (not over-blocked). Full build green.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
2026-06-19 01:27:02 +02:00

4.5 KiB

type, tags, sources, updated
type tags sources updated
entity
parking
stack
auth
offline-first
parking-system-architecture
2026-06-15

Local JWT Auth

Authentication and authorization, kept fully local — a direct consequence of offline-first (an air-gapped park cannot reach an external identity provider; see logto-zitadel-oidc for the rejected alternative). (See parking-system-architecture §2.)

  • @fastify/jwt signs tokens with a local secret (symmetric HMAC). The server refuses to start without a strong JWT_SECRET (≥32 chars, no placeholder) — there is deliberately no insecure default.
  • Session lifetime: valid until explicit logout — no time expiry (decision 2026-06-15, built). Booth reality breaks any fixed clock: relief arrives late, fails to show, or one operator is forced to work two shifts in a row — a token that expired mid-duty would strand an active operator. So the login persists until logout; a shift is a separate, explicit boundary, not tied to token lifetime. (Superseded the earlier "8h expiry, bound to a shift" assumption.) The JWT carries no exp; the cookie has a long fixed maxAge (30 days) so a browser restart doesn't log out an active operator, and logout clears it.
  • A users table in sqlite holds bcrypt password hashes plus a role_id FK. The first admin is seeded via pnpm --filter @parking/server seed-admin (no bootstrap endpoint); every other user is created in-app (admin → Users screen).
  • Authorization = dynamic RBAC (built 2026-06-18, replacing the old hardcoded admin/operator/cashier/readonly enum — those are now ordinary seed roles). Roles are data: roles + role_permissions tables, composed by an admin from a code-defined permission grid (@parking/shared PERMISSIONS = resource:action, e.g. tariff:update, payment:create, event:void). A preHandler requirePermission(...) per route checks a PERMISSION, not a role name. The JWT carries roleId (not the permission list); the guard resolves the role's permission set per-request from an in-memory cache (bumpPermsCache() on any role write), so editing a role applies immediately — no re-login, no token bloat. No Casbin/engine needed at this scale.
  • Protected built-in admin role (id='admin', builtin=1): non-editable, non-deletable, and always resolves to the FULL permission set in code. The app refuses to delete or downgrade the last user holding admin — administration can never be locked out of the appliance.
  • event:void is a permission, NOT a ledger delete: the append-only signed chain is untouched; the permission only gates who may APPEND a void event (there is no void API route yet — forward seam).
  • No privilege escalation through the RBAC system itself. role:create/role:update and user:create/user:update are themselves grantable, so a non-admin could otherwise self-escalate. Guards (routes/roles.ts, routes/users.ts): a caller may only put permissions on a role that they already hold, and may only assign/modify users whose role is a SUBSET of the caller's own (so no minting a privileged role, handing out the admin role, or resetting/deleting a more- privileged account). An admin holds the full set, so it is unrestricted — the intended behaviour.

The SPA never sees the JWT. Login (POST /api/auth/login) verifies bcrypt and sets two cookies:

  • parking_token — the JWT, HttpOnly + SameSite=Strict (+ Secure when NODE_ENV=production). JS can't read it; @fastify/jwt reads it from the cookie, not the Authorization header.
  • parking_csrf — a random token, readable by JS. The JWT also carries a matching csrf claim. On every mutation the SPA echoes the cookie in the X-CSRF-Token header; the guard requires header == cookie == the signed claim (double-submit CSRF). Safe reads are exempt.

Routes: login, logout (clears cookies), me (bootstraps SPA session on load). The dev react-vite-spa proxy and the prod nginx reverse proxy keep the SPA and API same-origin, so the cookies work without CORS. (This replaced an earlier dev-only SETUP_AUTH_BYPASS shim, now removed.)

Open decision: moving from the symmetric secret to an asymmetric key (RS256/EdDSA) so verifying hosts hold only a public key — open-questions #7. Relevant before any multi-host/multi-lane deployment.

Part of the technology-stack. License: MIT.