harden(oidc): pre-login UA/IP binding (MED-16) — RFC 9700 §4.7.1

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
This commit is contained in:
shankar0123
2026-05-10 23:18:23 +00:00
parent ecef8295bb
commit cb73547af5
18 changed files with 441 additions and 103 deletions
+20 -20
View File
@@ -196,7 +196,7 @@ func TestPreLoginAdapter_CreatePreLogin_GetActiveFailure(t *testing.T) {
keys := newStubSigningKeyLookup(nil)
keys.getActErr = errors.New("postgres unavailable")
a := NewPreLoginAdapter(repo, keys, "t-default", "")
_, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v")
_, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v", "", "")
if err == nil || !strings.Contains(err.Error(), "get active signing key") {
t.Errorf("err = %v, want wrapped 'get active signing key'", err)
}
@@ -210,7 +210,7 @@ func TestPreLoginAdapter_CreatePreLogin_DecryptFailure(t *testing.T) {
key.KeyMaterialEncrypted = []byte{0x03, 0x00, 0x01, 0x02} // bogus v3 blob
keys := newStubSigningKeyLookup(key)
a := NewPreLoginAdapter(repo, keys, "t-default", "passphrase-set")
_, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v")
_, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v", "", "")
if err == nil || !strings.Contains(err.Error(), "decrypt active key") {
t.Errorf("err = %v, want wrapped 'decrypt active key'", err)
}
@@ -223,7 +223,7 @@ func TestPreLoginAdapter_CreatePreLogin_RNGFailure(t *testing.T) {
a.SetRandReaderForTest(func(_ []byte) (int, error) {
return 0, errors.New("RNG drained")
})
_, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v")
_, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v", "", "")
if err == nil || !strings.Contains(err.Error(), "generate id") {
t.Errorf("err = %v, want wrapped 'generate id'", err)
}
@@ -234,7 +234,7 @@ func TestPreLoginAdapter_CreatePreLogin_PersistFailure(t *testing.T) {
repo.createErr = errors.New("FK violation")
keys := newStubSigningKeyLookup(activeKeyForTest(t, "sk-1"))
a := NewPreLoginAdapter(repo, keys, "t-default", "")
_, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v")
_, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v", "", "")
if err == nil || !strings.Contains(err.Error(), "persist row") {
t.Errorf("err = %v, want wrapped 'persist row'", err)
}
@@ -247,7 +247,7 @@ func TestPreLoginAdapter_CreatePreLogin_HappyPath(t *testing.T) {
repo := newStubPreLoginRepo()
keys := newStubSigningKeyLookup(activeKeyForTest(t, "sk-1"))
a := NewPreLoginAdapter(repo, keys, "t-default", "")
cookie, sid, err := a.CreatePreLogin(context.Background(), "op-x", "the-state", "the-nonce", "verifier-xxx")
cookie, sid, err := a.CreatePreLogin(context.Background(), "op-x", "the-state", "the-nonce", "verifier-xxx", "", "")
if err != nil {
t.Fatalf("CreatePreLogin: %v", err)
}
@@ -279,7 +279,7 @@ func TestPreLoginAdapter_CreatePreLogin_HappyPath(t *testing.T) {
func TestPreLoginAdapter_LookupAndConsume_MalformedCookie(t *testing.T) {
a := NewPreLoginAdapter(newStubPreLoginRepo(),
newStubSigningKeyLookup(activeKeyForTest(t, "sk-1")), "t-default", "")
_, _, _, _, err := a.LookupAndConsume(context.Background(), "definitely-not-a-cookie")
_, _, _, _, _, _, err := a.LookupAndConsume(context.Background(), "definitely-not-a-cookie")
if !errors.Is(err, ErrPreLoginNotFound) {
t.Errorf("err = %v, want ErrPreLoginNotFound", err)
}
@@ -292,14 +292,14 @@ func TestPreLoginAdapter_LookupAndConsume_UnknownSigningKey(t *testing.T) {
createKey := activeKeyForTest(t, "sk-1")
createKeys := newStubSigningKeyLookup(createKey)
createAdapter := NewPreLoginAdapter(repo, createKeys, "t-default", "")
cookie, _, err := createAdapter.CreatePreLogin(context.Background(), "op-x", "s", "n", "v")
cookie, _, err := createAdapter.CreatePreLogin(context.Background(), "op-x", "s", "n", "v", "", "")
if err != nil {
t.Fatalf("CreatePreLogin: %v", err)
}
emptyKeys := newStubSigningKeyLookup(nil) // sk-1 is not in this lookup
consumeAdapter := NewPreLoginAdapter(repo, emptyKeys, "t-default", "")
_, _, _, _, err = consumeAdapter.LookupAndConsume(context.Background(), cookie)
_, _, _, _, _, _, err = consumeAdapter.LookupAndConsume(context.Background(), cookie)
if !errors.Is(err, ErrPreLoginNotFound) {
t.Errorf("err = %v, want ErrPreLoginNotFound (unknown signing key)", err)
}
@@ -312,7 +312,7 @@ func TestPreLoginAdapter_LookupAndConsume_DecryptKeyFailure(t *testing.T) {
createKey := activeKeyForTest(t, "sk-1")
createKeys := newStubSigningKeyLookup(createKey)
createAdapter := NewPreLoginAdapter(repo, createKeys, "t-default", "")
cookie, _, err := createAdapter.CreatePreLogin(context.Background(), "op-x", "s", "n", "v")
cookie, _, err := createAdapter.CreatePreLogin(context.Background(), "op-x", "s", "n", "v", "", "")
if err != nil {
t.Fatalf("CreatePreLogin: %v", err)
}
@@ -322,7 +322,7 @@ func TestPreLoginAdapter_LookupAndConsume_DecryptKeyFailure(t *testing.T) {
corruptedKey.KeyMaterialEncrypted = []byte{0x03, 0x00, 0x01, 0x02} // bogus v3
corruptedKeys := newStubSigningKeyLookup(&corruptedKey)
consumeAdapter := NewPreLoginAdapter(repo, corruptedKeys, "t-default", "passphrase-set")
_, _, _, _, err = consumeAdapter.LookupAndConsume(context.Background(), cookie)
_, _, _, _, _, _, err = consumeAdapter.LookupAndConsume(context.Background(), cookie)
if !errors.Is(err, ErrPreLoginNotFound) {
t.Errorf("err = %v, want ErrPreLoginNotFound (decrypt failure → uniform sentinel)", err)
}
@@ -336,7 +336,7 @@ func TestPreLoginAdapter_LookupAndConsume_HMACMismatch(t *testing.T) {
createKey := activeKeyForTest(t, "sk-1")
createKeys := newStubSigningKeyLookup(createKey)
createAdapter := NewPreLoginAdapter(repo, createKeys, "t-default", "")
cookie, _, err := createAdapter.CreatePreLogin(context.Background(), "op-x", "s", "n", "v")
cookie, _, err := createAdapter.CreatePreLogin(context.Background(), "op-x", "s", "n", "v", "", "")
if err != nil {
t.Fatalf("CreatePreLogin: %v", err)
}
@@ -349,7 +349,7 @@ func TestPreLoginAdapter_LookupAndConsume_HMACMismatch(t *testing.T) {
swapped.KeyMaterialEncrypted = swappedMaterial
swappedKeys := newStubSigningKeyLookup(&swapped)
consumeAdapter := NewPreLoginAdapter(repo, swappedKeys, "t-default", "")
_, _, _, _, err = consumeAdapter.LookupAndConsume(context.Background(), cookie)
_, _, _, _, _, _, err = consumeAdapter.LookupAndConsume(context.Background(), cookie)
if !errors.Is(err, ErrPreLoginNotFound) {
t.Errorf("err = %v, want ErrPreLoginNotFound (HMAC mismatch)", err)
}
@@ -368,7 +368,7 @@ func TestPreLoginAdapter_LookupAndConsume_RepoNotFound(t *testing.T) {
plID := "pl-orphan-id"
cookie := session.SignCookieValue(plID, keys.active.ID, hmacKey)
_, _, _, _, err := a.LookupAndConsume(context.Background(), cookie)
_, _, _, _, _, _, err := a.LookupAndConsume(context.Background(), cookie)
if !errors.Is(err, ErrPreLoginNotFound) {
t.Errorf("err = %v, want ErrPreLoginNotFound (repo miss)", err)
}
@@ -378,12 +378,12 @@ func TestPreLoginAdapter_LookupAndConsume_RepoExpired(t *testing.T) {
repo := newStubPreLoginRepo()
keys := newStubSigningKeyLookup(activeKeyForTest(t, "sk-1"))
a := NewPreLoginAdapter(repo, keys, "t-default", "")
cookie, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v")
cookie, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v", "", "")
if err != nil {
t.Fatalf("CreatePreLogin: %v", err)
}
repo.expireOnNext = true
_, _, _, _, err = a.LookupAndConsume(context.Background(), cookie)
_, _, _, _, _, _, err = a.LookupAndConsume(context.Background(), cookie)
if !errors.Is(err, ErrPreLoginNotFound) {
t.Errorf("err = %v, want ErrPreLoginNotFound (expired → uniform sentinel)", err)
}
@@ -393,13 +393,13 @@ func TestPreLoginAdapter_LookupAndConsume_RepoOtherError(t *testing.T) {
repo := newStubPreLoginRepo()
keys := newStubSigningKeyLookup(activeKeyForTest(t, "sk-1"))
a := NewPreLoginAdapter(repo, keys, "t-default", "")
cookie, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v")
cookie, _, err := a.CreatePreLogin(context.Background(), "op-x", "s", "n", "v", "", "")
if err != nil {
t.Fatalf("CreatePreLogin: %v", err)
}
// Inject a non-NotFound, non-Expired error to exercise the wrap branch.
repo.wrappedErr = errors.New("postgres dropped connection")
_, _, _, _, err = a.LookupAndConsume(context.Background(), cookie)
_, _, _, _, _, _, err = a.LookupAndConsume(context.Background(), cookie)
if errors.Is(err, ErrPreLoginNotFound) {
t.Error("err must NOT be ErrPreLoginNotFound for non-sentinel repo failure")
}
@@ -412,11 +412,11 @@ func TestPreLoginAdapter_LookupAndConsume_HappyPath(t *testing.T) {
repo := newStubPreLoginRepo()
keys := newStubSigningKeyLookup(activeKeyForTest(t, "sk-1"))
a := NewPreLoginAdapter(repo, keys, "t-default", "")
cookie, _, err := a.CreatePreLogin(context.Background(), "op-okta", "the-state-42", "the-nonce-42", "the-verifier-42")
cookie, _, err := a.CreatePreLogin(context.Background(), "op-okta", "the-state-42", "the-nonce-42", "the-verifier-42", "", "")
if err != nil {
t.Fatalf("CreatePreLogin: %v", err)
}
pid, st, nn, vf, err := a.LookupAndConsume(context.Background(), cookie)
pid, st, nn, vf, _, _, err := a.LookupAndConsume(context.Background(), cookie)
if err != nil {
t.Fatalf("LookupAndConsume: %v", err)
}
@@ -425,7 +425,7 @@ func TestPreLoginAdapter_LookupAndConsume_HappyPath(t *testing.T) {
}
// Single-use: second consume returns ErrPreLoginNotFound.
_, _, _, _, err = a.LookupAndConsume(context.Background(), cookie)
_, _, _, _, _, _, err = a.LookupAndConsume(context.Background(), cookie)
if !errors.Is(err, ErrPreLoginNotFound) {
t.Errorf("second consume err = %v, want ErrPreLoginNotFound (single-use violated)", err)
}