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3 Commits

Author SHA1 Message Date
Chris Coutinho de99296779 feat: implement scope-based audience mapping and RFC 9728 support 
This commit removes hardcoded Keycloak audience mappers and implements
dynamic audience assignment based on OAuth client scopes and RFC 8707
resource indicators.

## MCP Server Changes

### Protected Resource Metadata (app.py)
- Change resource field from client_id to URL (RFC 9728 compliance)
- Use `{mcp_server_url}/mcp` as resource identifier
- Update DCR registration to include all Nextcloud API scopes
- Add resource_url parameter to client registration

### Client Registration (auth/client_registration.py)
- Add resource_url parameter to register_client()
- Pass resource_url to DCR endpoint
- Support RFC 9728 resource metadata

### Browser OAuth Routes (auth/browser_oauth_routes.py)
- Enhanced error logging for token exchange failures
- Log HTTP status code and response body for debugging
- Improved error messages for OAuth provisioning issues

### Token Verifier (auth/progressive_token_verifier.py)
- Add introspection_uri and client_secret parameters
- Initialize HTTP client for introspection requests
- Enable opaque token validation support

## Keycloak Configuration

### realm-export.json
- **Remove** hardcoded `audience-mcp-server` protocol mapper
- Audience now determined by client scopes:
  - External clients: RFC 8707 resource parameter → `aud: {resource_url}`
  - MCP Server: `token-exchange-nextcloud` scope → `aud: "nextcloud"`

### OIDC App (third_party/oidc)
- Updated submodule with RFC 9728 support
- Added resource_url database field
- Enhanced introspection authorization logic

## Architecture

Two separate audience flows:

1. **Gemini CLI → MCP Server**
   - Client requests: `resource=http://localhost:8002/mcp`
   - Token audience: `aud: "http://localhost:8002/mcp"`
   - MCP server validates via progressive_token_verifier

2. **MCP Server → Nextcloud APIs**
   - MCP server includes: `scope=token-exchange-nextcloud`
   - Token audience: `aud: "nextcloud"` (via scope mapper)
   - Nextcloud user_oidc validates via SelfEncodedValidator

## Benefits
- ✅ RFC 8707 compliant (resource indicators)
- ✅ RFC 9728 compliant (protected resource metadata)
- ✅ Dynamic audience based on OAuth context
- ✅ Fixes Gemini CLI authentication failures
- ✅ Maintains Nextcloud API access for background jobs
- ✅ Clear security boundaries between flows

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
 2025-11-04 05:28:58 +01:00
Chris Coutinho 01d1cf9190 feat: integrate token exchange into MCP server application 
Wire up RFC 8693 token exchange throughout the MCP server to support
stateless per-request token conversion for external IdP scenarios.

Changes:

Authentication Flow:
- Add exchange_token_for_audience() for pure RFC 8693 exchange
- Update context_helper to use stateless token exchange
- Remove fallback to standard OAuth on exchange failure
- Make storage initialization lazy (only for delegation, not MCP tools)

Application Configuration:
- Add ENABLE_TOKEN_EXCHANGE environment variable support
- Skip provisioning tools when token exchange enabled
- Pass mcp_client_id to token broker for proper validation
- Update docker-compose.yml with token exchange config

Token Exchange Service:
- Add TOKEN_EXCHANGE_GRANT constant
- Implement exchange_token_for_audience() method
- Support both "mcp-server" and client_id audiences
- Lazy storage initialization for delegation scenarios
- Enhanced error handling and logging

Progressive Token Verifier:
- Add mcp_client_id parameter for external IdP validation
- Accept both "mcp-server" and configured client_id
- Support external IdP token verification

Key Behavior Changes:
- When ENABLE_TOKEN_EXCHANGE=true: Each MCP tool call triggers
  stateless token exchange (client token → Nextcloud token)
- When ENABLE_TOKEN_EXCHANGE=false: Uses pass-through mode
  (validates Flow 1 token and passes to Nextcloud)
- No provisioning tools registered in exchange mode
- No refresh tokens needed for request-time operations

This completes the token exchange implementation. The MCP server now
supports both pass-through (default) and exchange (opt-in) modes for
federated authentication architectures.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
 2025-11-04 02:32:40 +01:00
Chris Coutinho d768909fd4 feat: Implement ADR-004 Progressive Consent foundation (partial) 
Implements Progressive Consent architecture with dual OAuth flows:
- Flow 1: Direct client authentication (aud: "mcp-server")
- Flow 2: Resource provisioning with refresh tokens

Components added:
- Client registry with validation (client_registry.py)
- Progressive token verifier (progressive_token_verifier.py)
- Token broker service integration
- Provisioning decorator for MCP tools
- OAuth provisioning tools (provision_nextcloud_access, etc.)

Configuration:
- Progressive Consent enabled by default (ENABLE_PROGRESSIVE_CONSENT=true)
- Client validation with pre-registered clients
- Audience separation framework

KNOWN ISSUE - Token Exchange Pattern Incorrect:
The current implementation does NOT properly implement token exchange.
MCP session tokens should be EXCHANGED for delegated Nextcloud tokens
during tool calls, not stored/reused. Critical corrections needed:

1. Session tokens: Flow 1 token → exchange → ephemeral Nextcloud token
   - Generated on-demand per tool call
   - Short-lived, not stored
   - Scopes limited to tool requirements

2. Background tokens: Flow 2 refresh token → background Nextcloud token
   - Only for offline/background jobs
   - Potentially different scopes than session tokens
   - Must NOT be used for MCP session tool calls

The token exchange mechanism needs to be implemented to properly
separate session-time delegation from background job authorization.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
 2025-11-03 20:33:55 +01:00