[4/15] Add PKCE and single-use state CSRF protection to the OAuth client flow - #157
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[4/15] Add PKCE and single-use state CSRF protection to the OAuth client flow#157UnknownJoe796 wants to merge 2 commits into
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I'll feel more comfortable with this when it tests against an external, official (if possible) OAuth server. |
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The OAuth client flow previously round-tripped a caller-supplied `state` through the provider without storing or validating it (TODO acknowledged in-code), and used no PKCE. - state/CSRF: the value sent to the provider is now an opaque 256-bit single-use nonce. At flow start a FlowRecord (caller state + PKCE verifier) is stored in the cache keyed by the nonce with a short TTL; the callback validates and consumes it via getAndRemove BEFORE any token exchange, so unknown/expired/replayed callbacks are rejected. The caller's app STATE is preserved server-side and still delivered to onAccess; it no longer leaks to the provider. - PKCE (RFC 7636): S256 code_challenge on the auth redirect and code_verifier on token exchange, gated by a per-provider supportsPkce flag (default true). Verified against the RFC Appendix B test vector. - Confirmed the redirect_uri (fixed callback URL) and final UI redirect (driven only by a server-signed Proof) are not attacker-controllable; documented rather than adding an unnecessary whitelist. Also fixes two latent bugs uncovered here: a NPE on code.state!! and an onError result that was computed then discarded (execution fell through). Requires a cache: OauthCallbackEndpoint/OauthProofEndpoints take a Runtime<Cache> and loginUrl is now suspend (source-breaking on the 5.x line). Docs note the shared-cache requirement for multi-instance deployments and the residual login-CSRF limitation of cookie-less state. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> (cherry picked from commit d0bc38c) (cherry picked from commit 72e2eed)
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More tests is good, but I want this tested against externally managed code. |
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Adds PKCE and single-use
stateCSRF protection to the OAuth client flow.Pkce.ktis new;OauthCallbackEndpointnow rejects reused or unknown statevalues.
OauthCallbackSecurityTestcovers the happy path and the replay andforgery cases.