# Add OAuth2 Protected Resource Metadata Endpoint
This PR implements the OAuth2 Protected Resource Metadata endpoint according to RFC 9728. The endpoint is available at `/.well-known/oauth-protected-resource` and provides information about Coder as an OAuth2 protected resource.
Key changes:
- Added a new endpoint at `/.well-known/oauth-protected-resource` that returns metadata about Coder as an OAuth2 protected resource
- Created a new `OAuth2ProtectedResourceMetadata` struct in the SDK
- Added tests to verify the endpoint functionality
- Updated API documentation to include the new endpoint
The implementation currently returns basic metadata including the resource identifier and authorization server URL. The `scopes_supported` field is empty until a scope system based on RBAC permissions is implemented. The `bearer_methods_supported` field is omitted as Coder uses custom authentication methods rather than standard RFC 6750 bearer tokens.
A TODO has been added to implement RFC 6750 bearer token support in the future.
## 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>
First PR in a series to address
https://github.com/coder/coder/issues/16230.
Introduces support for logging in via the [GitHub OAuth2 Device
Flow](https://docs.github.com/en/apps/oauth-apps/building-oauth-apps/authorizing-oauth-apps#device-flow).
It's previously been possible to configure external auth with the device
flow, but it's not been possible to use it for logging in. This PR
builds on the existing support we had to extend it to sign ins.
When a user clicks "sign in with GitHub" when device auth is configured,
they are redirected to the new `/login/device` page, which makes the
flow possible from the client's side. The recording below shows the full
flow.
https://github.com/user-attachments/assets/90c06f1f-e42f-43e9-a128-462270c80fdd
I've also manually tested that it works for converting from
password-based auth to oauth.
Device auth can be enabled by a deployment's admin by setting the
`CODER_OAUTH2_GITHUB_DEVICE_FLOW` env variable or a corresponding config
setting.
* fix: move oauth2 routes
From /login/oauth2/* to /oauth2/*.
/login/oauth2 causes /login to no longer get served by the frontend,
even if nothing is actually served on /login itself.
* Add forgotten comment on delete
These will show up when configuring the application along with the
client ID and everything else. Should make it easier to configure the
application, otherwise you will have to go look up the URLs in the
docs (which are not yet written).
Co-authored-by: Steven Masley <stevenmasley@gmail.com>
* Add database tables for OAuth2 applications
These are applications that will be able to use OAuth2 to get an API key
from Coder.
* Add endpoints for managing OAuth2 applications
These let you add, update, and remove OAuth2 applications.
* Add frontend for managing OAuth2 applications
