f9f0151717401d6fc7d3eb1dc0f9fe85cd960052
2 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 julien
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bfa35d3283 |
fix(portal-bff): drop strict amr check — flow blocked when Entra omits the claim (#108)
## Bug
After a real sign-in against the Entra tenant, the callback rejected the flow with:
```
{"context":"AuthCallback","event":"auth.flow_error","failure":{"kind":"amr-missing"}}
```
The user landed on the SPA with `?auth_error=amr-missing` instead of authenticated. Every dev sign-in is blocked.
## Root cause
PR #107's `amr-missing` guard misread ADR-0011's intent. `amr` is an **optional** claim in Entra ID tokens: it's populated for fresh interactive sign-ins where Conditional Access asked for an MFA method, and frequently absent for SSO / refresh flows or in tenants where no CA policy is configured on the app registration. Rejecting tokens on empty `amr` blocks every legitimate sign-in against such a tenant.
ADR-0011 actually specifies:
- **Conditional Access** (org-side) is the enforcement layer for "MFA happened".
- The **`@RequireMfa({ freshness: 600 })`** decorator (designed-in, no v1 consumer) is what guards sensitive routes.
- The BFF surfaces `amr` through the audit log and the future guard, not as a callback precondition.
## Fix
- **[`auth.errors.ts`](apps/portal-bff/src/auth/auth.errors.ts)**: drop the `amr-missing` variant from the `AuthCodeFlowError` discriminator. Three failure modes left: `state-mismatch`, `flow-expired`, `token-exchange-failed`. MSAL's ID-token validation (signature, issuer, audience, exp, nbf) is the real gate at this stage.
- **[`auth.service.ts`](apps/portal-bff/src/auth/auth.service.ts)**: `toAuthenticatedUser` keeps extracting `amr` and passing it through (as a possibly-empty string array) so the structured log line and the future `@RequireMfa` guard still see it. The strict `if (amr.length === 0) throw` is replaced by a comment explaining the new shape.
- **[`auth.service.spec.ts`](apps/portal-bff/src/auth/auth.service.spec.ts)**: the `'throws amr-missing'` test becomes `'returns the user even when the ID token has no amr claim'` — asserts the array passes through empty rather than blocking the flow.
## Verification
- `nx run-many -t lint test build --projects=portal-bff` — green. **52/52 specs**.
- Manual smoke: end-to-end sign-in against the live tenant now lands cleanly on the SPA; Pino's `auth.signed_in` log shows the resolved identity with `amr` (often `[]` until CA is configured on the org side).
---------
Co-authored-by: Julien Gautier <julien.gautier@apf.asso.fr>
Reviewed-on: #108
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julien
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c50794eceb |
feat(portal-bff): /auth/callback route — token exchange + amr check (#107)
## Summary
Fourth step of ADR-0009 wiring. Closes the OIDC round-trip on the BFF side (modulo session persistence — that's the next PR per ADR-0010). Entra now redirects the user back to `GET /api/auth/callback`; the BFF verifies the state, exchanges the code for tokens via MSAL's `acquireTokenByCode`, runs the ADR-0011 `amr` sanity-check, logs the resolved identity to Pino, clears the single-use pre-auth cookie, and 302s the user back to the SPA.
## What lands
- **[`auth.errors.ts`](apps/portal-bff/src/auth/auth.errors.ts)** — discriminated-union `AuthCodeFlowError` (`state-mismatch` / `flow-expired` / `amr-missing` / `token-exchange-failed`) + `AuthCodeFlowException` wrapper. The `kind` field doubles as the `?auth_error=<code>` query param on the SPA-bound redirect so the front-end can render an exact message without duplicating the string set.
- **[`AuthService.completeAuthCodeFlow(code, state, preAuth, now?)`](apps/portal-bff/src/auth/auth.service.ts)** — verifies state binding, refuses cookies older than the 5-minute flow TTL, calls MSAL Node's `acquireTokenByCode` with the stored verifier, validates `amr` is non-empty (the BFF sanity-check per ADR-0011 — Entra Conditional Access on the org side does the real enforcement), extracts `oid` / `tid` / `preferred_username` / `name` / `amr` into an `AuthenticatedUser` shape.
- **[`auth.cookie.ts`](apps/portal-bff/src/auth/auth.cookie.ts)** gains `clearPreAuthCookieOptions()` mirroring the set-options minus `maxAge` so the browser actually drops the cookie. (Cookies match by name + path + secure; getting any of those wrong leaves the old cookie in place.)
- **[`AuthController.callback()`](apps/portal-bff/src/auth/auth.controller.ts)** — `@Get('callback')`. Always clears the cookie first (single-use). Bails on Entra-side errors (`?error=`), missing query params, missing or malformed cookie — each branch logs a structured Pino warning and redirects with the right `auth_error` code. On `AuthCodeFlowException`, logs + redirects with the typed `kind`. On success, logs an `auth.signed_in` event with `oid`, `tid`, `username`, `amr` (PII-sensitive bits only; no tokens), then 302s to `entra.postLogoutRedirectUri`.
## Decisions worth flagging
- **`postLogoutRedirectUri` reused as the SPA root URL.** Semantically a tiny stretch (its OIDC role is the post-logout destination) but the value is the same. Avoids one more env var until / unless the two URLs need to diverge.
- **Cookie cleared FIRST**, before any branching. Single-use is a property we want guaranteed regardless of which path exits the handler — overlap with a parallel /login from the same browser session would otherwise leak a usable cookie.
- **`auth.signed_in` logged via Pino, not via the audit module.** ADR-0013 wants this in the audit table; pairing audit with the session that ships in the next PR keeps the audit row carrying a `session_id` (otherwise it'd reference a "phantom" auth event with no follow-up).
- **`amr` non-empty is the BFF's check; the Conditional Access policy is what enforces "MFA happened".** ADR-0011 explicitly factors it this way — empty `amr` would indicate a policy misconfiguration where MFA never fired.
## Verification
- `nx run-many -t lint test build --projects=portal-bff` — green.
- **52 / 52 specs** (was 39; +13 across the new completeFlow branches and callback branches).
- Service spec covers happy path + 6 failure modes (state mismatch, flow expired, amr missing, MSAL throws, MSAL returns null, oid claim missing).
- Controller spec covers happy redirect, Entra error, missing cookie, AuthCodeFlowException branch, missing query, malformed cookie.
## Manual smoke test (end-to-end)
1. `apps/portal-bff/.env` carries real `ENTRA_*` + `SESSION_SECRET`.
2. `nx serve portal-bff` and `nx serve portal-shell`.
3. Open `http://localhost:3000/api/auth/login` → redirects to Entra.
4. Authenticate. Entra redirects to `http://localhost:3000/api/auth/callback?code=…&state=…`.
5. BFF processes; redirects to `http://localhost:4200/`. Pino log shows `auth.signed_in` with the user's `oid`, `tid`, `username`, `amr`.
6. Tamper test: open the link again, hand-edit the `state=` in the callback URL → BFF redirects with `?auth_error=state-mismatch`.
## What this PR explicitly does NOT do
- **Persist a session.** The user is "authenticated" from the BFF's point of view (identity resolved + logged) but the next request lands anonymous. Closes in the Redis sessions PR per ADR-0010.
- **Audit log entry.** Pairs with sessions so the row carries a `session_id`.
- **Logout / `/me`.** Land after sessions.
---------
Co-authored-by: Julien Gautier <julien.gautier@apf.asso.fr>
Reviewed-on: #107
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