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>
* chore: refactor user subject logic to be in 1 place
* test: implement test to assert deleted custom roles are omitted
* add unit test for deleted role
* chore: create type for unique role names
Using `string` was confusing when something should be combined with
org context, and when not to. Naming this new name, "RoleIdentifier"
* chore: merge apikey/token session config values
There is a confusing difference between an apikey and a token. This
difference leaks into our configs. This change does not resolve the
difference. It only groups the config values to try and manage any
bloat that occurs from adding more similar config values
