Fixes critical finding 1 from security review round 2, 2026-08-22:
identify checked the per-source-IP throttle BEFORE verifying the
presented key. This plugin runs behind a Kubernetes Service, and with
externalTrafficPolicy: Cluster (this operator's own deployment),
r.RemoteAddr is the node's own SNAT address shared by every external
caller reaching that node — not a per-tenant address. 20 failed requests
from anywhere on the internet sharing that node locked out all 10 live
users, including the admin dashboard's own poll.
- identify now verifies the key FIRST, unconditionally: a valid key
always succeeds before any throttle state is read. Every failure path
still records against the caller's IP, but throttling is now pure
observability (bounding log volume and tracker memory), never
enforcement — an attacker with no valid key already got 'false'
either way, so nothing is lost against brute force.
- Replaces the per-source-IP tracker's backing store: the general-
purpose memoryStore (limits.go) has no size cap and a full mutex-held
sweep that scales with tracked-IP count (~83ms at 1M IPs). authFailureTracker
is a bounded, two-generation, O(1)-rotation structure capped at
2x50,000 entries (important finding 1).
- logAuthEvent now emits a distinct, separately rate-limited
'auth throttle:' line the first time a source crosses the limit
(important finding 5), and both the routine and throttle-engaged
lines report how many events they suppressed since the last line
actually written, so several distinct attacker IPs in one window no
longer collapse into a single indistinguishable line (important
finding 6).
- The success path no longer touches the throttle tracker's mutex at
all (important finding 2).
Fixes finding 3 from the 2026-08-22 security audit: authStore.identify
had no counter, no backoff, and no lockout on failed attempts, and
logger.go wrote one unbuffered stderr line per attempt including the
caller's RemoteAddr. An unauthenticated attacker got unlimited digest
guesses at line rate and could drive synchronous stderr writes on the
shared Traefik ingress.
- Add per-source-IP failure throttling to identify, reusing the existing
in-process memoryStore (limits.go) as authStore's own dedicated
instance rather than a new dependency: authFailureLimit (20) failed
attempts per authFailureWindow (1 minute) throttles further attempts
from that IP outright, including a subsequently valid key, and resets
once the window elapses.
- clientIP reads r.RemoteAddr only, never a client-supplied header,
matching the same trust boundary the rest of this package already
assumes (routes_passthrough.go strips X-Forwarded-*/X-Auth-* before any
outbound request).
- Rate-limit logAuthEvent's failure line via authStore.shouldLogAuthFailure,
the identical technique limiter.logStoreError already applies to store
errors. Successful-auth logging stays unbounded (bounded by legitimate,
already-authenticated traffic elsewhere).
lukaszraczylo