Harden OIDC token endpoints from security review

Fixes from review of the device flow / introspection / DCR work:

Introspection over-disclosure (RFC 7662):
- Restrict introspection to authorized callers — the client a token was issued
  to, or a resource server registered (resource_identifiers) to serve the token's
  bound RFC 8707 audience. Unauthorized callers get {active:false}, disclosing
  nothing, instead of any confidential client reading any token.
- Scope-gate disclosed claims: username only with the email scope, groups only
  with the groups scope (mirrors userinfo). ADR 0005.

Tokens minted for revoked users:
- Re-check application.user_allowed?(user) at mint time in the device, refresh,
  and authorization-code grants (covers app-active, user-active, group
  membership). A user deactivated or removed from the allowed group between
  approval and the token request is refused with access_denied. The refresh
  check runs before rotation so a denied refresh has no side effects.

Device authorization hardening:
- Require confidential clients to authenticate, and require PKCE (code_challenge)
  up front for clients that require it, so an intercepted device_code plus a
  known public client_id cannot redeem tokens.
- Merge (not overwrite) the shared consent record on device approval.

Tests: new oidc_introspection_test and oidc_mint_authorization_test; existing
PKCE/claims tests updated to grant app access (they created ungrouped apps and
relied on the token endpoint not checking authorization). Full suite green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01F7cwhwDJp3MJJDoNPVE6zq

This commit is contained in:

Dan Milne

2026-07-19 13:19:41 +10:00

co-authored by

Claude Opus 4.8

parent 2defa26a87

commit 017dfdff0e

14 changed files with 533 additions and 67 deletions

									
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				@@ -11,3 +11,4 @@ Each file is one decision. Newest decisions get the next number.

				| [0002](0002-device-authorization-grant.md) | CLI/agent auth uses the OAuth 2.0 Device Authorization Grant (RFC 8628) |

				| [0003](0003-dynamic-client-registration.md) | Dynamic Client Registration (RFC 7591), runtime-gated + default-deny |

				| [0004](0004-resource-indicators.md) | Resource Indicators (RFC 8707) bind token audience; pass-through validation |

				| [0005](0005-introspection-authorization.md) | Introspection restricted to authorized callers + claim scope-gating |