Opus Cross-cutting audit found a classic OIDC account-takeover hole in
kei-auth-google::verify(). Same class as the public Booking.com / Slack /
GitLab pattern.
Root cause: verify() accepted info.email from userinfo response as user_id
WITHOUT checking info.email_verified. A Google Workspace admin can mint
accounts with arbitrary unverified email aliases. Attacker then OAuth-flows
into the relying party using a victim's email as their alias and gets a
session bound to that user_id. No email verification = no auth.
Fix in 3 layers (defense in depth):
1. email_verified GATE
- client.rs: UserInfo gains email_verified: bool with #[serde(default)] —
absent field defaults to false (fail-closed).
- error.rs: new Error::EmailNotVerified variant.
- provider.rs::verify(): rejects with EmailNotVerified before any session
is built when email_verified != true.
2. sub AS PRIMARY user_id
- provider.rs::verify(): user_id = info.sub (Google's stable account id),
NOT info.email. Email is now mutable metadata only. Email reassignment
in Google Workspace cannot redirect an existing user_id binding.
3. id_token.sub CROSS-CHECK
- id_token.rs (new, 104 LOC): JWT-claims-only extract_sub() — parses
base64-payload without signature verification (signature verification
against Google JWKS is a documented follow-up atomar).
- provider.rs::verify(): when TokenResponse.id_token is present, decode
claims and require id_token.sub == userinfo.sub. New
Error::IdSubMismatch + IdTokenMalformed variants.
- This adds defense against a forged userinfo response even though
signature is not yet verified.
Constructor Pattern compliance: provider.rs split into provider.rs (181 LOC)
+ verify_helpers.rs (114 LOC, with unpack_challenge / check_state /
enforce_email_verified / cross_check_id_token_sub helpers). All files <200
LOC, all functions <30 LOC.
Tests added: tests/google_security_regression.rs (164 LOC, 5 dedicated
CVE-2023-7028 regression tests). All 26 tests pass:
- verify_rejects_unverified_email
- verify_rejects_missing_email_verified_field
- verify_uses_sub_not_email_as_user_id
- verify_rejects_id_token_sub_mismatch
- verify_accepts_matching_id_token_sub
cargo check --workspace clean. cargo test -p kei-auth-google: 26/26 pass.
Follow-up: JWT signature verification against Google's JWKS endpoint with
kid-based key cache + RS256/ES256 — separate atomar (~150 LOC).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
152 lines
5.1 KiB
Rust
152 lines
5.1 KiB
Rust
// SPDX-License-Identifier: Apache-2.0
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// Copyright 2026 <author org>
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//!
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//! Wiremock smoke tests for `GoogleAuthProvider`. No live HTTP.
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//!
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//! CVE-2023-7028 class regressions live in
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//! `tests/google_security_regression.rs`.
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use kei_auth_google::{GoogleAuthClient, GoogleAuthProvider};
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use kei_runtime_core::traits::auth::{AuthChallenge, AuthProvider, AuthSession};
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use serde_json::{json, Value};
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use wiremock::matchers::{body_string_contains, header, method, path};
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use wiremock::{Mock, MockServer, ResponseTemplate};
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fn client_for(server: &MockServer) -> GoogleAuthClient {
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GoogleAuthClient::with_urls(
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format!("{}/token", server.uri()),
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format!("{}/userinfo", server.uri()),
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"client-id-xyz",
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"client-secret-xyz",
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"https://example.com/cb",
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)
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.unwrap()
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}
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fn challenge(state: &str, code_verifier: Option<&str>) -> AuthChallenge {
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AuthChallenge::OAuthCode {
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provider: "google".into(),
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code: "code".into(),
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state: state.into(),
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expected_state: state.into(),
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code_verifier: code_verifier.map(str::to_string),
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}
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}
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async fn mock_token(server: &MockServer, body: Value) {
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Mock::given(method("POST"))
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.and(path("/token"))
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.respond_with(ResponseTemplate::new(200).set_body_json(body))
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.expect(1)
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.mount(server)
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.await;
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}
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async fn mock_userinfo(server: &MockServer, body: Value) {
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Mock::given(method("GET"))
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.and(path("/userinfo"))
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.respond_with(ResponseTemplate::new(200).set_body_json(body))
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.expect(1)
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.mount(server)
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.await;
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}
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async fn run_verify(
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server: &MockServer,
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state: &str,
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code_verifier: Option<&str>,
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) -> kei_runtime_core::Result<AuthSession> {
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let provider = GoogleAuthProvider::new(client_for(server), None).unwrap();
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provider.verify(&challenge(state, code_verifier)).await
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}
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#[tokio::test]
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async fn verify_end_to_end_builds_auth_session() {
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let server = MockServer::start().await;
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mock_token(&server, json!({
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"access_token": "tok", "expires_in": 1800, "id_token": null
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})).await;
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Mock::given(method("GET"))
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.and(path("/userinfo"))
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.and(header("authorization", "Bearer tok"))
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.respond_with(ResponseTemplate::new(200).set_body_json(json!({
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"sub": "999", "email": "bob@example.com",
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"email_verified": true, "name": "Bob"
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})))
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.expect(1)
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.mount(&server)
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.await;
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let session = run_verify(&server, "csrf-state-xyz", None).await.unwrap();
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// Post CVE-2023-7028 fix: user_id is the OIDC `sub`, not the email.
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assert_eq!(session.user_id, "999");
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assert_eq!(session.dna.role(), "session");
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assert!(session.dna.caps().contains("UI"));
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assert_eq!(session.parent_dna.role(), "primitive");
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assert!(session.parent_dna.caps().contains("GO"));
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assert!(session.expires_unix_ms > 0);
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}
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#[tokio::test]
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async fn issue_challenge_rejects_non_oauth() {
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let client = GoogleAuthClient::with_urls(
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"http://t/x", "http://u/x", "cid", "secret", "http://r/cb",
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).unwrap();
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let provider = GoogleAuthProvider::new(client, None).unwrap();
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let c = AuthChallenge::MagicLink { email: "a@b.c".into() };
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assert!(provider.issue_challenge(&c).await.is_err());
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}
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#[tokio::test]
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async fn verify_rejects_wrong_provider() {
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let client = GoogleAuthClient::with_urls(
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"http://t/x", "http://u/x", "cid", "secret", "http://r/cb",
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).unwrap();
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let provider = GoogleAuthProvider::new(client, None).unwrap();
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let c = AuthChallenge::OAuthCode {
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provider: "github".into(),
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code: "x".into(),
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state: "y".into(),
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expected_state: "y".into(),
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code_verifier: None,
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};
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assert!(provider.verify(&c).await.is_err());
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}
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#[tokio::test]
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async fn verify_rejects_csrf_state_mismatch() {
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let server = MockServer::start().await;
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let provider = GoogleAuthProvider::new(client_for(&server), None).unwrap();
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let c = AuthChallenge::OAuthCode {
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provider: "google".into(),
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code: "code".into(),
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state: "got-this-state".into(),
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expected_state: "expected-state".into(),
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code_verifier: None,
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};
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let err = provider.verify(&c).await.unwrap_err();
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assert!(
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format!("{err}").contains("CSRF"),
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"expected CSRF error, got: {err}"
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);
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}
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#[tokio::test]
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async fn verify_sends_code_verifier_when_challenge_carries_some() {
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let server = MockServer::start().await;
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Mock::given(method("POST"))
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.and(path("/token"))
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.and(body_string_contains("code_verifier=my-pkce-verifier"))
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.respond_with(ResponseTemplate::new(200).set_body_json(json!({
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"access_token": "tok-pkce", "expires_in": 900, "id_token": null
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})))
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.expect(1)
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.mount(&server)
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.await;
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mock_userinfo(&server, json!({
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"sub": "pkce-sub", "email": "pkce@example.com",
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"email_verified": true, "name": "PKCE"
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})).await;
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let session = run_verify(&server, "st", Some("my-pkce-verifier")).await.unwrap();
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// Post-fix: user_id == OIDC `sub`, not email.
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assert_eq!(session.user_id, "pkce-sub");
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}
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