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With TRUSTED_PROXIES empty behind the reverse proxy production is required to run behind, every login POST keyed on the proxy's address and shared one 5/minute bucket. A stranger sending five POSTs a minute -- 0.08 requests per second, from anywhere -- kept that bucket permanently full, and the operator's own correct password was answered 429 indefinitely with no second administrative path. The login POST no longer has a pre-emptive limiter. The handler verifies credentials first and spends budget only on a FAILED attempt, so a correct password is never throttled whatever the counters hold. Three things follow, and are implemented together because the first is unsafe without the other two: - Failures are counted per (client bucket, submitted username), five per minute, after which further failures get 429 with a Retry-After. A successful login clears the counter, so mistyping and then succeeding does not leave the operator throttled. - Both key sets are capped at 1024 entries. The submitted username is attacker-controlled, so past the first cap failures fall back to a counter keyed on the client alone, and past both caps a failure is answered as throttled without being recorded. Tracked state stays under half a megabyte and does not grow with invented usernames. - Concurrent Argon2id verifications are capped at two, a 128 MB ceiling at 64 MB per hash, and the queue for those slots is capped at 16 waiters. Every password-hashing endpoint takes a slot, including the password-change endpoint, which holds one across both its hashes. A request that waits five seconds without a slot is answered 503, and one that arrives with the queue already full is shed with 503 immediately rather than joining it. Bounding the wait alone would not bound memory, and the queue depth is sized from what a parked waiter measurably retains rather than from the 1 MB body cap, which bounds only the raw body read. The body-cap, CSRF and form-parsing middleware all run before the guard, so a waiter holds its parsed form plus its request header block for the whole wait. Measured on the pinned go1.26.1 toolchain as the HeapAlloc delta across two GCs with 64 waiters parked in the handler: an ordinary two-field login form retains ~0 MB, a 1 MB urlencoded body at Go's 10,000-parameter parse cap retains 2.82 MB (3.09 MB with %41 escapes), and the ~0.9 MB of headers the 1 MB header cap allows takes it to 4.18 MB. The retained parse and the header block dominate, not the raw body. So 16 waiters: 16 x 4.18 MB is about 67 MB of committed queue memory, and two slots drain a full 16-deep queue in about 0.6 s, far inside the deadline. Peak commitment for the endpoint is about 203 MB — 128 MB of Argon2id plus the 18 requests holding a parsed form, 16 queued and the 2 being hashed, at about 75 MB. An unknown username is verified against a dummy hash instead of returning early, so a nonexistent account costs the same time as a real one and the response cannot be used to enumerate usernames. The password-change limiter is unchanged: RequireAuth runs ahead of it, so only a request already carrying a valid session reaches its bucket. Two consequences are documented rather than fixed, because they follow from the shape the issue asks for. Online guessing throughput rises from 5 a minute to roughly 27 a second, about 2.3 million a day: the credential check always precedes the counter, so the 429 is a label on the response rather than a gate in front of the hash, and what bounds brute force is the semaphore. And under a sustained flood the residual exposure is a loss of login availability, not merely of latency -- above about 27 requests a second most attempts are shed with 503, so a determined flood still denies login for as long as it runs. It costs roughly 400x more to run, nothing accumulates, and the first attempt after it stops succeeds. Restarting the service does not help: the counters a restart clears are not what is saturated. Also adds the missing test for the third bucketKey call site, where the peer is a trusted proxy but the forwarded chain names no client. Every existing test of that fallback uses an IPv4 proxy, where bucketKey is the identity function, so dropping the /64 masking there left the suite green. README and the TRUSTED_PROXIES startup warning updated: a shared bucket now costs precision, not the availability of the admin path.
74 lines
1.9 KiB
Go
74 lines
1.9 KiB
Go
package database
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import (
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"context"
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"log/slog"
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"os"
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"time"
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"go.uber.org/fx"
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)
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// NewTestRetentionReaper builds a RetentionReaper backed by the given
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// main database and per-webhook database manager, without the fx
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// lifecycle. Intended for tests.
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func NewTestRetentionReaper(
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db *Database,
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mgr *WebhookDBManager,
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) *RetentionReaper {
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return &RetentionReaper{
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db: db,
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dbManager: mgr,
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log: slog.New(slog.NewTextHandler(
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os.Stderr,
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&slog.HandlerOptions{Level: slog.LevelDebug},
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)),
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interval: time.Hour,
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}
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}
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// ExportSweep runs a single retention sweep synchronously for tests.
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func (r *RetentionReaper) ExportSweep(ctx context.Context) {
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r.sweep(ctx)
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}
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// ExportRegisterHooks registers the reaper's real fx lifecycle hooks
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// on a lifecycle supplied by a test, so a test can drive the exact
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// OnStart/OnStop functions the application runs and hand OnStart the
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// kind of context fx actually supplies.
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func (r *RetentionReaper) ExportRegisterHooks(lc fx.Lifecycle) {
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r.registerHooks(lc)
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}
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// ExportStart starts the reaper's background loop for tests.
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func (r *RetentionReaper) ExportStart() {
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r.start()
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}
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// ExportStop stops the reaper's background loop for tests.
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func (r *RetentionReaper) ExportStop(ctx context.Context) error {
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return r.stop(ctx)
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}
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// ExportWedgeLoop adds a goroutine to the reaper's WaitGroup that
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// never observes cancellation and returns only when release is
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// closed. It stands in for a sweep stuck on a locked database.
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func (r *RetentionReaper) ExportWedgeLoop(
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release <-chan struct{},
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) {
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r.wg.Go(func() {
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<-release
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})
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}
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// ExportSetInterval overrides the sweep interval for tests.
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func (r *RetentionReaper) ExportSetInterval(d time.Duration) {
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r.interval = d
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}
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// DummyPasswordHashForTest exposes the encoded hash that unknown
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// usernames are verified against.
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func DummyPasswordHashForTest() string {
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return dummyPasswordHash()
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}
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