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shankar0123
cb73547af5
Audit 2026-05-10 MED-16 closure.
WHAT.
Binds the OIDC pre-login row to the (clientIP, userAgent) tuple of
the /auth/oidc/login request, and enforces a constant-time compare
against the /auth/oidc/callback request at consume time. Defeats
replay of a stolen pre-login cookie by a different browser /
source — the secondary defense layer recommended by RFC 9700 §4.7.1
when the primary layer (HMAC integrity + Path=/ + SameSite=Lax on
the cookie) is bypassed via CSRF / XSS / TLS-termination leak.
WHY.
Pre-fix, the pre-login cookie's HMAC verified only that 'some'
caller of /auth/oidc/login was talking to /auth/oidc/callback; it
did not verify that the SAME browser / source was on both sides.
An attacker who exfiltrated the cookie value via any vector could
replay the bytes through their own user-agent and ride the victim's
authorization. RFC 9700 §4.7.1 calls out the gap explicitly and
recommends binding state to a user-agent fingerprint + source IP.
HOW.
Migration:
migrations/000044_prelogin_uaip.up.sql
ALTER TABLE oidc_pre_login_sessions
ADD COLUMN IF NOT EXISTS client_ip TEXT,
ADD COLUMN IF NOT EXISTS user_agent TEXT;
Both nullable for in-flight rolling-deploy compat — the consume-
side check only enforces when both row AND request carry non-empty
values for the leg in question.
Domain:
internal/repository/oidc.go (PreLoginSession) — adds ClientIP +
UserAgent fields.
Repository:
internal/repository/postgres/oidc_prelogin.go — Create persists
via sql.NullString (empty → NULL); LookupAndConsume reads back.
Re-uses package-local nullableString from discovery.go.
Service:
internal/auth/oidc/service.go
- PreLoginStore.CreatePreLogin signature takes (clientIP,
userAgent) as positions 5–6.
- PreLoginStore.LookupAndConsume returns (clientIP, userAgent)
as positions 5–6.
- HandleAuthRequest signature gains (clientIP, userAgent),
threaded to the store.
- HandleCallback adds Step 1.5 — UA / IP constant-time compare
between stored row and incoming request. Per-leg toggles via
preLoginRequireUA / preLoginRequireIP service fields. Empty
values on either side pass through (rolling-deploy + headless-
proxy compat).
- New sentinels ErrPreLoginUAMismatch, ErrPreLoginIPMismatch.
- SetPreLoginBindingRequirements(requireUA, requireIP) helper
for main.go config wiring.
Adapter:
internal/auth/oidc/prelogin.go — PreLoginAdapter passes the new
fields through to the repo row.
Handler:
internal/api/handler/auth_session_oidc.go
- OIDCAuthHandshaker.HandleAuthRequest signature updated.
- LoginInitiate captures clientIPFromRequest + r.UserAgent()
and passes to the service.
- classifyOIDCFailure adds errors.Is dispatch for the two new
sentinels → prelogin_ua_mismatch / prelogin_ip_mismatch
audit categories.
Config:
internal/config/config.go
+ AuthConfig.OIDCPreLoginRequireUA (default true)
env CERTCTL_OIDC_PRELOGIN_REQUIRE_UA
+ AuthConfig.OIDCPreLoginRequireIP (default true)
env CERTCTL_OIDC_PRELOGIN_REQUIRE_IP
cmd/server/main.go calls oidcService.SetPreLoginBindingRequirements
from cfg.Auth.OIDCPreLoginRequire{UA,IP}.
Tests (internal/auth/oidc/service_test.go):
- TestService_HandleCallback_MED16_UAMismatchRejected
- TestService_HandleCallback_MED16_IPMismatchRejected
- TestService_HandleCallback_MED16_BothMatch_Succeeds
- TestService_HandleCallback_MED16_LegacyRowEmptyValues (rolling-
deploy compat — empty stored values pass through)
- TestService_HandleCallback_MED16_RequireUAFalse_AllowsMismatch
(operator escape-hatch — UA mismatch silently allowed)
Mechanical fan-out:
- stubPreLogin / stubPreLoginRepo signatures updated.
- All existing call sites in service_test.go (~40), prelogin_test.go,
bench_test.go, logging_test.go, provider_enabled_test.go,
integration_keycloak_test.go, integration_okta_smoke_test.go,
auth_session_oidc_test.go updated to pass empty strings for the
new params — pre-existing tests do not exercise UA/IP binding
semantics.
VERIFY.
- go vet ./internal/auth/oidc/... ./internal/api/handler/...
./internal/config/... PASS
- go test -short -count=1 -run MED16 ./internal/auth/oidc/... PASS (5/5)
- go test -short -count=1 ./internal/auth/oidc/... PASS (4.6s)
- go test -short -count=1 ./internal/api/handler/... PASS (4.3s)
- go test -short -count=1 ./internal/config/... PASS
Refs: cowork/auth-bundles-audit-2026-05-10.md MED-16
cowork/auth-bundles-fixes-2026-05-10/HANDOFF.md item 6
RFC 9700 §4.7.1 — OAuth 2.0 Security Best Current Practice