Ask for the account password before minting an app password, and keep
sessions the proxy checks from writing the account's own registry objects,
so a session left open on someone else's machine cannot take a credential
away from it. The password is compared with what the session holds; Stalwart
is asked only when 2FA moved the session onto an app password.
Serve attachments and proxied images with no-store on a device that is not
the person's own. Give files from a winmail.dat only the types the server
would show inline. Strip direction controls from sender and attachment
names and from saved filenames.
On signing out, send what is inside its undo window, then close every
composer, so the next person to sign in does not find the last one's draft.
Group sessions by the account Stalwart names and its server, so "sign out
other sessions" also reaches a session opened as a bare or differently
cased username.
The server writes to one path and no other: SESSION_FILE, from sessions.ts.
Everything else it touches on disk it only reads. So a container with a
read-only root filesystem already works -- except that `VOLUME ["/data"]`
quietly undid it. Docker acts on that directive: a container started without
`-v` gets an anonymous volume mounted there anyway, writable even under
`--read-only`. It persisted nothing across a redeploy, since each new container
got a fresh empty volume, and it left an orphan behind every time one was
replaced. Deployments that want the sessions to survive already say so
themselves -- docker-compose.yml and deploy.example.sh both mount a named
volume -- so removing the line changes nothing for them.
IMMUTABLE=1 asserts that this is how the instance is running. It is checked
rather than believed: the server refuses to start if SESSION_FILE is still set,
or if the filesystem it is installed on turns out to be writable. Left
unchecked the misconfiguration is silent, because persisting sessions is
best-effort -- a read-only /data costs one warning at the first sign-in and
nothing more until the instance is replaced and everyone is signed out.
SessionBackend names what the rest of the server asks of a session store, and
`sessions` in app.ts is typed as it. Nothing changes today; SessionStore is
still the only implementation. It is there so the OAuth work is written against
the interface rather than the class, and so the interface can record which of
its methods a stateless backend could satisfy alone: create, resolve, reseal
and destroy each touch one session, while listForUser and destroyAllForUser
have to reach sessions other than the caller's. The second of those carries the
guarantee that changing a password invalidates the sessions still holding the
old one, which is why it needs a registry -- Stalwart's token registry, once
sign-in goes through OAuth.
Settings › Security grows three working sections instead of a note telling
people to use Stalwart's own portal.
Stalwart moved this API between releases, so ihasmail speaks both: 0.16+ has
the x:AccountPassword singleton and x:AppPassword registry objects over JMAP,
while 0.15.x has the /api/account/auth REST endpoint. Which one answers the
probe is the only reliable way to tell them apart, and the result is cached
per session. The built-in `user` role already grants sysAccountPassword* and
sysAppPassword*, so no administrator setup is needed.
Two problems are worth calling out, because both would bite a user hard:
Stalwart validates the credentials already on the account when 2FA is turned
on and never checks the new secret, so an authenticator that was mistyped or
out of step would lock someone out of their mailbox at the next sign-in. We
verify a code against the new secret ourselves first (RFC 6238, tested against
the spec's vectors) and only then ask the server to store anything.
Every proxied call re-authenticates with the credential sealed into the
session, and from the moment 2FA is on Stalwart wants a fresh TOTP code with
it — which we cannot produce between requests. Turning 2FA on would therefore
sign the user out of the browser they just turned it on in. App passwords
authenticate without a second factor, so the session is moved onto one minted
for this browser, and the session cookie is re-sealed with it. The order
matters: it is minted while the old credential still works, and revoked again
if enabling then fails.
Password changes re-seal this session too and drop the others, whose sealed
copies of the old password would fail on their next call.
The mock now enforces what a real server does — current password, password
policy, a TOTP code on every request once 2FA is on, app passwords exempt —
so the whole flow is exercised in tests rather than only by hand.
jcoffey-dev