## Changes
- **Commit 1**: Remove 17 unnecessary `//nolint` directives:
- `//nolint:varnamelen` — linter not active
- `//nolint:unused` on exported `SlimUnsupported`
- `//nolint:govet` in `coderd/httpmw/csrf` — no longer fires
- `//nolint:revive` on functions refactored since the nolint was added
- `//nolint:paralleltest` citing Go 1.22 loop variable capture
(obsolete)
- Bare `//nolint` narrowed to specific `//nolint:gocritic` with
justification
- **Commit 2**: Fix root causes behind 5 dangerous nolint suppressions:
- Add `MinVersion: tls.VersionTLS12` to TLS client config (removes
`gosec` G402)
- Delete trivial unexported wrappers `apiKey()`/`normalizeProvider()` in
chatprovider (removes `revive` confusing-naming)
- Add doc comments to `StartWithAssert` and `Router` (removes `revive`
exported)
- Rename unused parameters to `_` in integration test helpers
> 🤖 This PR was created using Coder Agents and reviewed by me.
## Summary
Harden the OAuth2 provider with multiple security fixes addressing
`coder/security#121` (CSRF session takeover) and converge on OAuth 2.1
compliance.
### Security Fixes
| Fix | Description | Commits |
|-----|-------------|---------|
| **CSRF on `/oauth2/authorize`** | Enforce CSRF protection on the
authorize endpoint POST (consent form submission) | `ba7d646`, `b94a64e`
|
| **Clickjacking: `frame-ancestors` CSP** | Prevent consent page from
being iframed (`Content-Security-Policy: frame-ancestors 'none'` +
`X-Frame-Options: DENY`) | `597aeb2` |
| **Exact redirect URI matching** | Changed from prefix matching to full
string exact matching per OAuth 2.1 §4.1.2.1 | `73d64b1`, `93897f1` |
| **Store & verify `redirect_uri`** | Store redirect_uri with auth code
in DB, verify at token exchange matches exactly (RFC 6749 §4.1.3) |
`50569b9`, `d7ca315` |
| **Mandatory PKCE** | Require `code_challenge` at authorization (for
`response_type=code`) + unconditional `code_verifier` verification at
token exchange | `d7ca315`, `1cda1a9` |
| **Reject implicit grant** | `response_type=token` now returns
`unsupported_response_type` error page (OAuth 2.1 removes implicit flow)
| `d7ca315`, `91b8863` |
### Changes by File
**`coderd/httpmw/csrf.go`** — Extended the CSRF `ExemptFunc` to enforce
CSRF on `/oauth2/authorize` in addition to `/api` routes. The consent
form POST is now CSRF-protected to prevent cross-site authorization code
theft.
**`site/site.go`** — Added `Content-Security-Policy: frame-ancestors
'none'` and `X-Frame-Options: DENY` headers to `RenderOAuthAllowPage`
(consent page only — does not affect the SPA/global CSP used by AI
tasks).
**`coderd/httpapi/queryparams.go`** — Changed `RedirectURL` from prefix
matching (`strings.HasPrefix(v.Path, base.Path)`) to full URI exact
matching (`v.String() != base.String()`), comparing scheme, host, path,
and query.
**`coderd/oauth2provider/authorize.go`** — Added PKCE enforcement:
`code_challenge` is required when `response_type=code` (via a
conditional check, not `RequiredNotEmpty`, so `response_type=token` can
reach the explicit rejection path). `ShowAuthorizePage` (GET) validates
`response_type` before rendering and returns a 400 error page for
unsupported types. `ProcessAuthorize` (POST) stores the `redirect_uri`
with the auth code when explicitly provided.
**`coderd/oauth2provider/tokens.go`** — PKCE verification is now
unconditional (not gated on `code_challenge` being present in DB). If
the stored code has a `redirect_uri`, the token endpoint verifies it
matches exactly — mismatch returns `errBadCode` → `invalid_grant`.
Missing `code_verifier` returns `invalid_grant`.
**`codersdk/oauth2.go`** — `OAuth2ProviderResponseTypeToken` constant
and `Valid()` acceptance are **kept** so the authorize handler can parse
`response_type=token` and return the proper `unsupported_response_type`
error rather than failing at parameter validation.
**`coderd/database/migrations/000421_*`** — Added `redirect_uri text`
column to `oauth2_provider_app_codes`.
### Design Decisions
**`state` parameter remains optional** — The plan initially required
`state` via `RequiredNotEmpty`, but this was reverted in `376a753` to
avoid breaking existing clients. The `state` is still hashed and stored
when provided (via `state_hash` column), securing clients that opt in.
**`response_type=token` kept in `Valid()`** — Removing it from `Valid()`
would cause the parameter parser to reject the request before the
authorize handler can return the proper `unsupported_response_type`
error. The constant is kept for correct error handling flow.
**CSP scoped to consent page only** — `frame-ancestors 'none'` is set
only on the OAuth consent page renderer, not globally. The SPA/global
CSP was previously changed to allow framing for AI tasks
([#18102](https://github.com/coder/coder/pull/18102)); this change does
not regress that.
### Out of Scope (follow-up PRs)
- Bearer tokens in query strings (needs internal caller audit)
- Scope enforcement on OAuth2 tokens
- Rate limiting on dynamic client registration
---
<details>
<summary>📋 Implementation Plan</summary>
# Plan: Harden OAuth2 Provider — Security Fixes + OAuth 2.1 Compliance
## Context & Why
Security issue `coder/security#121` reports a critical session takeover
via CSRF on the OAuth2 provider. This plan covers all remaining security
fixes from that issue **plus** convergence on OAuth 2.1 requirements.
The goal is a single PR that closes all actionable gaps.
## Current State (already committed on branch `csrf-sjx1`)
| Fix | Status | Commits |
|-----|--------|---------|
| Fix 1: CSRF on `/oauth2/authorize` | ✅ Done | `ba7d646`, `b94a64e` |
| CSRF token in consent form HTML | ✅ Done | `b94a64e` |
| `state_hash` column + storage | ✅ Done (hash stored, but state still
optional) | `9167d83`, `b94a64e` |
| Tests for CSRF + state hash | ✅ Done | `e4119b5` |
## Remaining Work
### ~~Fix 2 — Require `state` parameter~~ (DROPPED)
> **Decision:** Do not enforce `state` as required. The `state`
parameter is still hashed and stored when provided (via
`hashOAuth2State` / `state_hash` column from prior commits), but clients
are not forced to supply it. This avoids breaking existing integrations
that omit state.
**Rollback:** Remove `"state"` from the `RequiredNotEmpty` call in
`coderd/oauth2provider/authorize.go:42`:
```go
// BEFORE (current on branch)
p.RequiredNotEmpty("response_type", "client_id", "state", "code_challenge")
// AFTER
p.RequiredNotEmpty("response_type", "client_id", "code_challenge")
```
No test changes needed — tests already pass `state` voluntarily.
### Fix 4 — Exact redirect URI matching
Currently `coderd/httpapi/queryparams.go:233` uses prefix matching:
```go
// CURRENT — prefix match
if v.Host != base.Host || !strings.HasPrefix(v.Path, base.Path) {
```
OAuth 2.1 requires **exact string matching**. Change to:
```go
// AFTER — exact match (OAuth 2.1 §4.1.2.1)
if v.Host != base.Host || v.Path != base.Path {
```
**File: `coderd/httpapi/queryparams.go` — `RedirectURL` method**
Also update the error message from "must be a subset of" to "must
exactly match".
**Additionally**, store `redirect_uri` with the auth code and verify at
the token endpoint (RFC 6749 §4.1.3):
1. **New migration** (same migration file or a new `000421`): Add
`redirect_uri text` column to `oauth2_provider_app_codes`
2. **Update INSERT query** in `coderd/database/queries/oauth2.sql` to
include `redirect_uri`
3. **`coderd/oauth2provider/authorize.go`**: Store
`params.redirectURL.String()` when inserting the code
4. **`coderd/oauth2provider/tokens.go`**: After retrieving the code from
DB, verify that `redirect_uri` from the token request matches the stored
value exactly. Currently `tokens.go:103` calls `p.RedirectURL(vals,
callbackURL, "redirect_uri")` for prefix validation only — it must
compare against the stored redirect_uri from the code, not just the
app's callback URL.
<details>
<summary>Why both exact match AND store+verify?</summary>
Exact matching at the authorize endpoint prevents open redirectors
(attacker can't use a sub-path).
Storing and verifying at the token endpoint prevents code injection — an
attacker who steals a code can't exchange it with a different
redirect_uri than was originally authorized. This is required by RFC
6749 §4.1.3 and OAuth 2.1.
</details>
### Fix 7 — `frame-ancestors` CSP on consent page
The consent page can be iframed by a workspace app (same-site), which is
the attack vector. Add a `Content-Security-Policy` header to prevent
framing.
**File: `site/site.go` — `RenderOAuthAllowPage` function (~line 731)**
Before writing the response, add:
```go
func RenderOAuthAllowPage(rw http.ResponseWriter, r *http.Request, data RenderOAuthAllowData) {
rw.Header().Set("Content-Type", "text/html; charset=utf-8")
// Prevent the consent page from being framed to mitigate
// clickjacking attacks (coder/security#121).
rw.Header().Set("Content-Security-Policy", "frame-ancestors 'none'")
rw.Header().Set("X-Frame-Options", "DENY")
...
```
Both headers for defense-in-depth (CSP for modern browsers,
X-Frame-Options for legacy).
### OAuth 2.1 — Mandatory PKCE
Currently PKCE is checked only when `code_challenge` was provided during
authorization (`tokens.go:258`):
```go
// CURRENT — conditional check
if dbCode.CodeChallenge.Valid && dbCode.CodeChallenge.String != "" {
// verify PKCE
}
```
OAuth 2.1 requires PKCE for ALL authorization code flows. Change to:
**File: `coderd/oauth2provider/authorize.go`** — Add `"code_challenge"`
to required params:
```go
p.RequiredNotEmpty("response_type", "client_id", "code_challenge")
```
**File: `coderd/oauth2provider/tokens.go:257-265`** — Make PKCE
verification unconditional:
```go
// AFTER — PKCE always required (OAuth 2.1)
if req.CodeVerifier == "" {
return codersdk.OAuth2TokenResponse{}, errInvalidPKCE
}
if !dbCode.CodeChallenge.Valid || dbCode.CodeChallenge.String == "" {
// Code was issued without a challenge — should not happen
// with the authorize endpoint enforcement, but defend in
// depth.
return codersdk.OAuth2TokenResponse{}, errInvalidPKCE
}
if !VerifyPKCE(dbCode.CodeChallenge.String, req.CodeVerifier) {
return codersdk.OAuth2TokenResponse{}, errInvalidPKCE
}
```
**File: `codersdk/oauth2.go`** — Remove
`OAuth2ProviderResponseTypeToken` from the enum or reject it explicitly
in the authorize handler. Currently it's defined at line 216 but the
handler ignores `response_type` and always issues a code. We should
either:
- (a) Remove the `"token"` variant from the enum and reject it with
`unsupported_response_type`, OR
- (b) Add an explicit check in `ProcessAuthorize` that rejects
`response_type=token`
Option (b) is simpler and more backwards-compatible:
```go
// In ProcessAuthorize, after extracting params:
if params.responseType != codersdk.OAuth2ProviderResponseTypeCode {
httpapi.WriteOAuth2Error(ctx, rw, http.StatusBadRequest,
codersdk.OAuth2ErrorCodeUnsupportedResponseType,
"Only response_type=code is supported")
return
}
```
### OAuth 2.1 — Bearer tokens in query strings
`coderd/httpmw/apikey.go:743` accepts `access_token` from URL query
parameters. OAuth 2.1 prohibits this. However, this may be used
internally (e.g., workspace apps, DERP). Need to audit callers before
removing.
**Approach:** This is a larger change with potential breakage. Mark as a
**separate follow-up issue** rather than including in this PR. Document
the finding.
### OAuth 2.1 — Removed flows
✅ **Already compliant.** `tokens.go` only supports `authorization_code`
and `refresh_token` grant types. The implicit grant
(`response_type=token`) will be explicitly rejected per the PKCE section
above.
### OAuth 2.1 — Refresh token rotation
✅ **Already compliant.** `tokens.go:442` deletes the old API key when a
refresh token is used.
## Migration Plan
All DB changes can go in a single new migration (or extend 000420 if the
branch is rebased before merge). Columns to add:
- `redirect_uri text` on `oauth2_provider_app_codes`
The `state_hash` column is already added by migration 000420.
## Implementation Order
1. **Fix 7** — CSP headers on consent page (isolated, no deps)
2. ~~**Fix 2** — Require `state` parameter~~ (DROPPED — state stays
optional)
3. **Fix 4** — Exact redirect URI matching + store/verify redirect_uri
4. **PKCE mandatory** — Require `code_challenge` + reject
`response_type=token`
5. **Rollback** — Remove `"state"` from `RequiredNotEmpty` in
`authorize.go`
6. **Tests** — Update/add tests for all changes
7. **`make gen`** after DB changes
## Out of Scope (separate PRs)
- Bearer tokens in query strings (needs internal caller audit)
- Scope enforcement on OAuth2 tokens
- Rate limiting / quota on dynamic client registration
</details>
---
_Generated with [`mux`](https://github.com/coder/mux) • Model:
`anthropic:claude-opus-4-6` • Thinking: `xhigh`_
# Add RFC 6750 Bearer Token Authentication Support
This PR implements RFC 6750 Bearer Token authentication as an additional authentication method for Coder's API. This allows clients to authenticate using standard OAuth 2.0 Bearer tokens in two ways:
1. Using the `Authorization: Bearer <token>` header
2. Using the `access_token` query parameter
Key changes:
- Added support for extracting tokens from both Bearer headers and access_token query parameters
- Implemented proper WWW-Authenticate headers for 401/403 responses with appropriate error descriptions
- Added comprehensive test coverage for the new authentication methods
- Updated the OAuth2 protected resource metadata endpoint to advertise Bearer token support
- Enhanced the OAuth2 testing script to verify Bearer token functionality
These authentication methods are added as fallback options, maintaining backward compatibility with Coder's existing authentication mechanisms. The existing authentication methods (cookies, session token header, etc.) still take precedence.
This implementation follows the OAuth 2.0 Bearer Token specification (RFC 6750) and improves interoperability with standard OAuth 2.0 clients.
* chore: fix csrf error message on empty session header
A more detailed error message was added to catch mismatched
session tokens. This error was mistakenly applying to all CSRF
failures.
* chore: swagger docs omit brower based credentials, rely on swagger auth
Swagger has an "Authorize" button which should be the only
authentication being used in the api requests
* feat: enable csrf token header
* Exempt external auth requets
* ensure dev server bypasses CSRF
* external auth is just get requests
* Add some more routes
* Extra assurance nothing breaks
* chore: add /v2 to import module path
go mod requires semantic versioning with versions greater than 1.x
This was a mechanical update by running:
```
go install github.com/marwan-at-work/mod/cmd/mod@latest
mod upgrade
```
Migrate generated files to import /v2
* Fix gen
* chore: rename `AgentConn` to `WorkspaceAgentConn`
The codersdk was becoming bloated with consts for the workspace
agent that made no sense to a reader. `Tailnet*` is an example
of these consts.
* chore: remove `Get` prefix from *Client functions
* chore: remove `BypassRatelimits` option in `codersdk.Client`
It feels wrong to have this as a direct option because it's so infrequently
needed by API callers. It's better to directly modify headers in the two
places that we actually use it.
* Merge `appearance.go` and `buildinfo.go` into `deployment.go`
* Merge `experiments.go` and `features.go` into `deployment.go`
* Fix `make gen` referencing old type names
* Merge `error.go` into `client.go`
`codersdk.Response` lived in `error.go`, which is wrong.
* chore: refactor workspace agent functions into agentsdk
It was odd conflating the codersdk that clients should use
with functions that only the agent should use. This separates
them into two SDKs that are closely coupled, but separate.
* Merge `insights.go` into `deployment.go`
* Merge `organizationmember.go` into `organizations.go`
* Merge `quota.go` into `workspaces.go`
* Rename `sse.go` to `serversentevents.go`
* Rename `codersdk.WorkspaceAppHostResponse` to `codersdk.AppHostResponse`
* Format `.vscode/settings.json`
* Fix outdated naming in `api.ts`
* Fix app host response
* Fix unsupported type
* Fix imported type
Cian Johnston