"Link Mobile App" only appeared for OAuth sessions, its step-up could
only go through the identity provider (which failed without an OAuth
client and bounced password+TOTP users to the provider's login page),
and it handed the phone the desktop's own refresh token. Revoking that
token on sign-out, or a rotating provider, signed the phone out too; a
confidential client stopped the phone at its first token expiry; and an
identity provider on another host was refused by the app.
The step-up now mints the phone's own grant:
- Password and password+TOTP accounts confirm the current password (and
code) in the dialog. The server uses it once to get an OAuth grant
from Stalwart's structured login for the app's own client, retries
with the webmail's client when the server insists on a registered one,
and falls back to an app password ("Bulwark mobile (paired <date>)")
or, on servers that offer neither, the verified password. Failed
attempts are limited per account so the webmail's address cannot be
banned by guessing through it.
- SSO accounts keep the provider round trip, now with `offline_access`
where offered; its fresh tokens become the phone's grant instead of
being thrown away, and must belong to the account being paired.
- The account and server always come from the slot's verified session
context, never from the request.
Grants live 5 minutes server-side, codes 2 minutes, both single use; the
store is pinned on `globalThis`. Redeem answers `invalid_code`,
`expired_code` or `used_code`, and the desktop polls a separate status
id to replace the QR with "Signed in on your phone". A phone whose
client is confidential, or whose provider is on another host, renews
through `/api/auth/pair/token` with a sealed refresh token, so current
app builds work unchanged. Signing out discards a pending grant but no
longer affects a paired phone.
The dialog shows for every account (not in Lite), with a copyable
sign-in link, a TOTP field when needed, and the app's own "Scan a
sign-in code" wording.
The Stalwart bundle's README told admins to use
`releases/latest/download/bulwark-lite-stalwart.zip` as `resourceUrl`.
Stalwart re-downloads that URL on its own schedule and checks no hash or
signature, so whatever the newest release held would run as script on
the Stalwart origin next to the web admin.
The README now installs from the tagged release, explains updating by
moving `resourceUrl` to the next tag, and describes the floating URL as
an opt-in with that risk spelled out. Release runs upload a `.sha256`
next to each Lite zip.
The static export's header policy has to allow inline scripts (the
hydration scripts differ per page and one header cannot list them all),
so any injected inline script ran. The Stalwart bundle had no policy at
all: Stalwart sends no security headers for an Application, and nothing
stopped another site from framing it.
- Postbuild gives every page of the static target a `<meta>` CSP that
allows exactly the page's own inline scripts; enforced together with
the host's header, it takes away `'unsafe-inline'`. `verify` fails a
page whose inline scripts are not all pinned.
- The Stalwart entry document carries a `<meta>` CSP (no plugins, eval,
foreign scripts or moved `<base>`; its shells are rewritten at runtime,
so hashes are not possible there) and refuses to run inside a frame
of another origin.
- The nginx and Caddy examples send the same CSP as `_headers`.
Linus Rath