# OAuth2 Provider Code Reorganization
This PR reorganizes the OAuth2 provider code to improve separation of concerns and maintainability. The changes include:
1. Migrating OAuth2 provider app validation tests from `coderd/oauth2_test.go` to `oauth2provider/provider_test.go`
2. Moving OAuth2 client registration validation tests to `oauth2provider/validation_test.go`
3. Adding new comprehensive test files for metadata and validation edge cases
4. Renaming `OAuth2ProviderAppSecret` to `AppSecret` for better naming consistency
5. Simplifying the main integration test in `oauth2_test.go` to focus on core functionality
The PR maintains all existing test coverage while organizing the code more logically, making it easier to understand and maintain the OAuth2 provider implementation. This reorganization will help with future enhancements to the OAuth2 provider functionality.
# Refactor OAuth2 Provider Code into Dedicated Package
This PR refactors the OAuth2 provider functionality by moving it from the main `coderd` package into a dedicated `oauth2provider` package. The change improves code organization and maintainability without changing functionality.
Key changes:
- Created a new `oauth2provider` package to house all OAuth2 provider-related code
- Moved existing OAuth2 provider functionality from `coderd/identityprovider` to the new package
- Refactored handler functions to follow a consistent pattern of returning `http.HandlerFunc` instead of being handlers directly
- Split large files into smaller, more focused files organized by functionality:
- `app_secrets.go` - Manages OAuth2 application secrets
- `apps.go` - Handles OAuth2 application CRUD operations
- `authorize.go` - Implements the authorization flow
- `metadata.go` - Provides OAuth2 metadata endpoints
- `registration.go` - Handles dynamic client registration
- `revoke.go` - Implements token revocation
- `secrets.go` - Manages secret generation and validation
- `tokens.go` - Handles token issuance and validation
This refactoring improves code organization and makes the OAuth2 provider functionality more maintainable while preserving all existing behavior.
# Remove unique constraint on OAuth2 provider app names
This PR removes the unique constraint on the `name` field in the `oauth2_provider_apps` table to comply with RFC 7591, which only requires unique client IDs, not unique client names.
Changes include:
- Removing the unique constraint from the database schema
- Adding migration files for both up and down migrations
- Removing the name uniqueness check in the in-memory database implementation
- Updating the unique constraint constants
Change-Id: Iae7a1a06546fbc8de541a52e291f8a4510d57e8a
Signed-off-by: Thomas Kosiewski <tk@coder.com>
# Implement OAuth2 Dynamic Client Registration (RFC 7591/7592)
This PR implements OAuth2 Dynamic Client Registration according to RFC 7591 and Client Configuration Management according to RFC 7592. These standards allow OAuth2 clients to register themselves programmatically with Coder as an authorization server.
Key changes include:
1. Added database schema extensions to support RFC 7591/7592 fields in the `oauth2_provider_apps` table
2. Implemented `/oauth2/register` endpoint for dynamic client registration (RFC 7591)
3. Added client configuration management endpoints (RFC 7592):
- GET/PUT/DELETE `/oauth2/clients/{client_id}`
- Registration access token validation middleware
4. Added comprehensive validation for OAuth2 client metadata:
- URI validation with support for custom schemes for native apps
- Grant type and response type validation
- Token endpoint authentication method validation
5. Enhanced developer documentation with:
- RFC compliance guidelines
- Testing best practices to avoid race conditions
- Systematic debugging approaches for OAuth2 implementations
The implementation follows security best practices from the RFCs, including proper token handling, secure defaults, and appropriate error responses. This enables third-party applications to integrate with Coder's OAuth2 provider capabilities programmatically.
This pull request implements RFC 8707, Resource Indicators for OAuth 2.0 (https://datatracker.ietf.org/doc/html/rfc8707), to enhance the security of our OAuth 2.0 provider.
This change enables proper audience validation and binds access tokens to their intended resource, which is crucial
for preventing token misuse in multi-tenant environments or deployments with multiple resource servers.
## Key Changes:
* Resource Parameter Support: Adds support for the resource parameter in both the authorization (`/oauth2/authorize`) and token (`/oauth2/token`) endpoints, allowing clients to specify the intended resource server.
* Audience Validation: Implements server-side validation to ensure that the resource parameter provided during the token exchange matches the one from the authorization request.
* API Middleware Enforcement: Introduces a new validation step in the API authentication middleware (`coderd/httpmw/apikey.go`) to verify that the audience of the access token matches the resource server being accessed.
* Database Schema Updates:
* Adds a `resource_uri` column to the `oauth2_provider_app_codes` table to store the resource requested during authorization.
* Adds an `audience` column to the `oauth2_provider_app_tokens` table to bind the issued token to a specific audience.
* Enhanced PKCE: Includes a minor enhancement to the PKCE implementation to protect against timing attacks.
* Comprehensive Testing: Adds extensive new tests to `coderd/oauth2_test.go` to cover various RFC 8707 scenarios, including valid flows, mismatched resources, and refresh token validation.
## How it Works:
1. An OAuth2 client specifies the target resource (e.g., https://coder.example.com) using the resource parameter in the authorization request.
2. The authorization server stores this resource URI with the authorization code.
3. During the token exchange, the server validates that the client provides the same resource parameter.
4. The server issues an access token with an audience claim set to the validated resource URI.
5. When the client uses the access token to call an API endpoint, the middleware verifies that the token's audience matches the URL of the Coder deployment, rejecting any tokens intended for a different resource.
This ensures that a token issued for one Coder deployment cannot be used to access another, significantly strengthening our authentication security.
---
Change-Id: I3924cb2139e837e3ac0b0bd40a5aeb59637ebc1b
Signed-off-by: Thomas Kosiewski <tk@coder.com>
## Summary
This PR implements critical MCP OAuth2 compliance features for Coder's authorization server, adding PKCE support, resource parameter handling, and OAuth2 server metadata discovery. This brings Coder's OAuth2 implementation significantly closer to production readiness for MCP (Model Context Protocol)
integrations.
## What's Added
### OAuth2 Authorization Server Metadata (RFC 8414)
- Add `/.well-known/oauth-authorization-server` endpoint for automatic client discovery
- Returns standardized metadata including supported grant types, response types, and PKCE methods
- Essential for MCP client compatibility and OAuth2 standards compliance
### PKCE Support (RFC 7636)
- Implement Proof Key for Code Exchange with S256 challenge method
- Add `code_challenge` and `code_challenge_method` parameters to authorization flow
- Add `code_verifier` validation in token exchange
- Provides enhanced security for public clients (mobile apps, CLIs)
### Resource Parameter Support (RFC 8707)
- Add `resource` parameter to authorization and token endpoints
- Store resource URI and bind tokens to specific audiences
- Critical for MCP's resource-bound token model
### Enhanced OAuth2 Error Handling
- Add OAuth2-compliant error responses with proper error codes
- Use standard error format: `{"error": "code", "error_description": "details"}`
- Improve error consistency across OAuth2 endpoints
### Authorization UI Improvements
- Fix authorization flow to use POST-based consent instead of GET redirects
- Remove dependency on referer headers for security decisions
- Improve CSRF protection with proper state parameter validation
## Why This Matters
**For MCP Integration:** MCP requires OAuth2 authorization servers to support PKCE, resource parameters, and metadata discovery. Without these features, MCP clients cannot securely authenticate with Coder.
**For Security:** PKCE prevents authorization code interception attacks, especially critical for public clients. Resource binding ensures tokens are only valid for intended services.
**For Standards Compliance:** These are widely adopted OAuth2 extensions that improve interoperability with modern OAuth2 clients.
## Database Changes
- **Migration 000343:** Adds `code_challenge`, `code_challenge_method`, `resource_uri` to `oauth2_provider_app_codes`
- **Migration 000343:** Adds `audience` field to `oauth2_provider_app_tokens` for resource binding
- **Audit Updates:** New OAuth2 fields properly tracked in audit system
- **Backward Compatibility:** All changes maintain compatibility with existing OAuth2 flows
## Test Coverage
- Comprehensive PKCE test suite in `coderd/identityprovider/pkce_test.go`
- OAuth2 metadata endpoint tests in `coderd/oauth2_metadata_test.go`
- Integration tests covering PKCE + resource parameter combinations
- Negative tests for invalid PKCE verifiers and malformed requests
## Testing Instructions
```bash
# Run the comprehensive OAuth2 test suite
./scripts/oauth2/test-mcp-oauth2.sh
Manual Testing with Interactive Server
# Start Coder in development mode
./scripts/develop.sh
# In another terminal, set up test app and run interactive flow
eval $(./scripts/oauth2/setup-test-app.sh)
./scripts/oauth2/test-manual-flow.sh
# Opens browser with OAuth2 flow, handles callback automatically
# Clean up when done
./scripts/oauth2/cleanup-test-app.sh
Individual Component Testing
# Test metadata endpoint
curl -s http://localhost:3000/.well-known/oauth-authorization-server | jq .
# Test PKCE generation
./scripts/oauth2/generate-pkce.sh
# Run specific test suites
go test -v ./coderd/identityprovider -run TestVerifyPKCE
go test -v ./coderd -run TestOAuth2AuthorizationServerMetadata
```
### Breaking Changes
None. All changes maintain backward compatibility with existing OAuth2 flows.
---
Change-Id: Ifbd0d9a543d545f9f56ecaa77ff2238542ff954a
Signed-off-by: Thomas Kosiewski <tk@coder.com>
