Raphaël Bosi
56245a35af
The Google/Microsoft callback for a sign-in with no target workspace
redirected to `/sign-in-up?tokenPair={...}`, putting a 60-day refresh
token in a query string. Those persist in browser history, `Referer`
headers and access logs.
It now carries a single-use, 5-minute opaque token in the URL fragment,
which the frontend exchanges over POST. Browsers never send the fragment
on the wire, so the token stays out of access logs, proxies and
`Referer` headers entirely. Redemption claims the row with a `DELETE`
guarded on `revokedAt`/`deletedAt` being null, so concurrent requests
cannot each mint a refresh token and a revoked token cannot redeem.
Enterprise SSO (OIDC/SAML) already used a POST exchange and is
unchanged.
```mermaid
sequenceDiagram
participant Browser
participant Server
participant DB
Note over Browser,Server: before, the redirect carried access + 60-day refresh in ?tokenPair
Browser->>Server: GET /auth/google/redirect
Server->>DB: store sha256(token), expires in 5 min
Server-->>Browser: 302 /sign-in-up#ssoExchangeToken=opaque
Note over Browser: fragment never sent back to any server
Browser->>Server: POST getAuthTokensFromSSOExchangeToken
Server->>DB: guarded DELETE, single-use claim
Server-->>Browser: access + refresh token, in the response body
```
Since the token is single-use, the refresh token is minted at redemption
instead of at callback, so an abandoned redirect leaves an inert expired
hash rather than a live credential.
Redemption lives in its own `SignInUpSSOExchangeTokenEffect` +
`useRedeemSSOExchangeToken`, mirroring the existing
`VerifyLoginTokenEffect` + `useVerifyLogin` pair, so
`SignInUpGlobalScopeFormEffect` only loses the vulnerable branch. Like
`useVerifyLogin`, the hook clears any stale token pair before
exchanging. The effect reads `window.location.hash` live and strips it
synchronously, which doubles as the StrictMode double-invocation latch.
Remaining exposure is the browser itself (history until the synchronous
strip, client-side scripts), same as any fragment-based OAuth response.
`loginToken` on the workspace-targeted branch still travels as
`/verify?loginToken=` and is replayable for 15 minutes; moving it to the
fragment too is a separate change.
A fast instance command adds a unique partial index on `("type",
"value")` for live SSO exchange tokens, so redemption is an index lookup
instead of a full scan of the shared token table and at most one row can
ever match.