- MeshPskProviderRefreshTests: GatedResolver.Entered was set by the priming
refresh and never reset, so Wait() returned before the held refresh reached
the store and the mid-refresh call-count snapshot raced its increment
(expected 1, was 2). Hold() now resets it.
- FailedCredentialLockoutTests all-bad burst: the 15 waiters could queue
before a slot holder ran the increment after BeginAsync (authenticated 0
vs 5). The wait now covers both conditions; the security assertions are
unchanged.
Both looped 20x locally, 0 failures.
Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk
#844: a success cleared the whole per-client count, so a client holding a valid
key could make four guesses at another key id, sign in with its own, and repeat
forever. Failures are now charged to the (client, credential identity) pair --
IOpcUaUserAuthenticator.DescribeCredential, key:<keyId> for API keys -- and to
the client as a whole. A success clears only its own identity's count; the
per-identity threshold locks that identity; a new per-client cap
(OpcUa:CredentialLockout:MaxFailedAttemptsPerClient, default 2 x
MaxFailedAttempts) that a success never resets bounds spraying across key ids
and locks every credential. Slots are bounded on both counts; a waiter whose
identity has room is not held behind one whose identity has none.
#845: (1) store timeouts, miss-budget refusals, store/authenticator exceptions,
an unset pepper and cancellation are reported Transient
(OpcUaUserAuthResult.Unavailable) and released uncounted, so a ConfigDb stall
can no longer lock every keyed client out; the client still sees the same
opaque denial. (2) a full 4096-entry table defers its next prune until the
earliest entry could age out instead of rescanning under the lock per failure.
(3) ApplicationUri deliberately NOT added to the key: on a None channel it is a
free string, so it would let an attacker reset the count per guess --
documented. (4) wire tests: distinct client certificates on a Sign endpoint are
locked out separately; the ApplicationConfigPath branch keeps the SDK lockout
off (falsified by removing the loaded-branch disable).
A legitimate consumer opening several keyed sessions at once from one key
(e.g. a ScadaBridge site node behind one NAT IP on a None endpoint) must
never see BadUserAccessDenied for parallelism. BeginAsync now hands out at
most MaxFailedAttempts - recordedFailures verification slots per key;
further activations queue FIFO and are woken as slots free. A waiter is
refused only when the key locks out (never reaching the authenticator) or,
uncounted, after OpcUa:CredentialLockout:SlotWaitSeconds (default 10,
BadTimeout). Cancelled waiters are dequeued; pruning accounts for waiters.
The security property is unchanged: no more than MaxFailedAttempts
unverified guesses in progress-or-failed per window.
- Reserve an in-flight slot per client before authenticating (TryBegin /
Complete / Abandon under one lock); refuse once recorded failures +
in-flight attempts reach MaxFailedAttempts, so a parallel burst cannot
pass the check before its first failure is recorded.
- An expired lockout resets the count (LockoutSeconds < FailureWindowSeconds
relocked on every single failure after the first lockout).
- Validate OpcUa:CredentialLockout at host start: disabled, or both
durations > 0.
- Log the first refusal of a lockout episode at Information, the rest at
Debug.
- Document that on None endpoints the key is effectively IP-only (NAT
neighbours share a UserName count) and a null peer shares one key.
OPC Foundation SDK 2.0.1's SessionManager lockout refused EVERY
activation (Anonymous included, before the token is read) from a client
with 5 failed identity validations in 60 s, for 5 minutes, keyed on cert
thumbprint else peer IP. Disable it (MaxFailedAuthenticationAttempts=0
on built and loaded configs) and enforce FailedCredentialLockout in the
identity-registry adapter instead: UserName activations only, keyed on
thumbprint+peer together, same 5/60s/300s defaults, configurable via
OpcUa:CredentialLockout.
Joseph Doherty