Files
coder/codersdk/mcp.go
T
Atif Ali 261269aff0 fix: support path-aware OAuth discovery for remote MCP (#30168)
## Problem

VS Code discovers Coder's MCP endpoint as a path-qualified OAuth
resource, but Coder advertises the deployment root. Accepting MCP-bound
tokens also requires keeping REST-backed tool calls within the
originating MCP resource rather than granting those tokens direct REST
access.

## Fix

- Publish path-aware protected resource metadata and authentication
challenges; keep authorization-server metadata at the root.
- Validate the MCP audience and delegate tool requests through a private
in-process transport that retains identity, scopes, expiry, revocation,
and streaming cancellation.
- Reject unsupported MCP path aliases and validate SDK path components
before URL resolution.
- Add discovery, audience, authorization, endpoint-isolation, and
transport lifecycle regression tests and update integration docs.

## Validation

VS Code completed OAuth and returned the authenticated user through a
real MCP tool. Official MCP SDK 1.30.1 completed discovery,
registration, PKCE, tool execution, and refresh. These live checks
preceded the final path hardening; the hardened paths are covered by
automated regressions.

Affected Go package tests, targeted race tests, backend/SDK lint, and
targeted documentation checks passed during self-review. The exact PR
commit was also checked separately from the uncommitted consent-scope
fix.

> [!NOTE]
> Tokens are MCP-audience-bound, but grants still include `coder:all`;
least-privilege scopes remain a separate requirement
([PLAT-639](https://linear.app/codercom/issue/PLAT-639)).

Preview:
https://coder.com/docs/@fix/mcp-internal-delegation/ai-coder/mcp-server

<details>
<summary>Implementation decisions and review context</summary>

1. Treat `/api/experimental/mcp/http` and its single-trailing-slash form
as supported MCP resource paths; reject other aliases and descendants
before route authentication.
2. Preserve deployment-root discovery and authorization-server metadata
for existing REST integrations.
3. Bind private delegation to the authenticated API-key ID. Revalidate
the original credential and enforce normal RBAC/scopes on every internal
REST request; do not derive delegation from HTTP headers.
4. Keep internal HTTP, streaming, and WebSocket traffic in-process with
no network fallback. Close the transport on outer-request cancellation
and normal completion.
5. Validate workspace owner/name path segments before SDK URL
construction, including tool-level tests that malformed arguments cannot
select a different REST endpoint.
6. Keep compatibility and delegated tool execution together:
discovery-only changes would allow authentication while leaving real MCP
tool calls broken.

</details>

> 🤖 This PR was created with the help of Coder Agents, and needs a human
review. 🧑💻
2026-10-09 00:58:39 +05:00

336 lines
14 KiB
Go

package codersdk
import (
"context"
"fmt"
"net/http"
"time"
"github.com/google/uuid"
)
// MCPEndpoint is the remote MCP HTTP endpoint path.
const MCPEndpoint = "/api/experimental/mcp/http"
// MCPServerOAuth2ConnectURL returns the URL the user should visit to
// start the OAuth2 flow for an MCP server. The frontend opens this
// in a new window/popup.
func (c *Client) MCPServerOAuth2ConnectURL(organizationID, id uuid.UUID) string {
return fmt.Sprintf("%s/api/v2/organizations/%s/mcp-servers/%s/oauth2/connect", c.URL.String(), organizationID, id)
}
// MCPServerOAuth2DisconnectResponse reports whether the removed token
// was also revoked at the OAuth provider.
type MCPServerOAuth2DisconnectResponse struct {
TokenRevoked bool `json:"token_revoked"`
TokenRevocationError string `json:"token_revocation_error,omitempty"`
}
// MCPServerOAuth2Disconnect removes the user's OAuth2 token for an
// MCP server. Use MCPServerOAuth2DisconnectWithResponse for the
// provider revocation outcome.
func (c *Client) MCPServerOAuth2Disconnect(ctx context.Context, id uuid.UUID) error {
_, err := c.MCPServerOAuth2DisconnectWithResponse(ctx, id)
return err
}
// MCPServerOAuth2DisconnectWithResponse removes the user's OAuth2
// token for an MCP server and reports the provider revocation outcome.
func (c *Client) MCPServerOAuth2DisconnectWithResponse(ctx context.Context, id uuid.UUID) (MCPServerOAuth2DisconnectResponse, error) {
res, err := c.Request(ctx, http.MethodDelete, fmt.Sprintf("/api/v2/mcp/servers/%s/oauth2/disconnect", id), nil)
if err != nil {
return MCPServerOAuth2DisconnectResponse{}, err
}
defer res.Body.Close()
// Servers from before provider revocation respond 204 without a body.
if res.StatusCode == http.StatusNoContent {
return MCPServerOAuth2DisconnectResponse{}, nil
}
if res.StatusCode != http.StatusOK {
return MCPServerOAuth2DisconnectResponse{}, ReadBodyAsError(res)
}
var resp MCPServerOAuth2DisconnectResponse
return resp, ReadBodyAsJSON(res, &resp)
}
// MCPServerConfig represents an admin-configured MCP server.
type MCPServerConfig struct {
ID uuid.UUID `json:"id" format:"uuid"`
OrganizationID uuid.UUID `json:"organization_id" format:"uuid"`
DisplayName string `json:"display_name"`
Slug string `json:"slug"`
Description string `json:"description"`
IconURL string `json:"icon_url"`
Transport string `json:"transport"` // "streamable_http" or "sse"
URL string `json:"url"`
AuthType string `json:"auth_type"` // "none", "oauth2", "api_key", "custom_headers", "user_oidc"
// OAuth2 fields (only populated for admins).
OAuth2ClientID string `json:"oauth2_client_id,omitempty"`
HasOAuth2Secret bool `json:"has_oauth2_secret"`
OAuth2AuthURL string `json:"oauth2_auth_url,omitempty"`
OAuth2TokenURL string `json:"oauth2_token_url,omitempty"`
OAuth2RevocationURL string `json:"oauth2_revocation_url,omitempty"`
OAuth2Scopes string `json:"oauth2_scopes,omitempty"`
// API key fields (only populated for admins).
APIKeyHeader string `json:"api_key_header,omitempty"`
HasAPIKey bool `json:"has_api_key"`
HasCustomHeaders bool `json:"has_custom_headers"`
// Tool governance.
ToolAllowList []string `json:"tool_allow_list"`
ToolDenyList []string `json:"tool_deny_list"`
// Availability policy set by admin.
Availability string `json:"availability"` // "force_on", "default_on", "default_off"
Enabled bool `json:"enabled"`
ModelIntent bool `json:"model_intent"`
AllowInPlanMode bool `json:"allow_in_plan_mode"`
// ForwardCoderHeaders forwards the same Coder identity headers we
// send to LLM providers (X-Coder-Owner-Id, X-Coder-Chat-Id, and the
// optional X-Coder-Subchat-Id and X-Coder-Workspace-Id) to this
// MCP server on every request. Off by default to avoid leaking
// chat identity to third-party servers.
ForwardCoderHeaders bool `json:"forward_coder_headers"`
HasSigningSecret bool `json:"has_signing_secret"`
CreatedAt time.Time `json:"created_at" format:"date-time"`
UpdatedAt time.Time `json:"updated_at" format:"date-time"`
// Per-user state (populated for non-admin requests).
AuthConnected bool `json:"auth_connected"`
}
// MCPServerConfigRole is a role a user or group holds in an MCP server
// config's access control list.
type MCPServerConfigRole string
const (
MCPServerConfigRoleRead MCPServerConfigRole = "read"
// MCPServerConfigRoleDeleted removes the principal's ACL entry when
// used in an update request.
MCPServerConfigRoleDeleted MCPServerConfigRole = ""
)
// MCPServerConfigACL is the resolved access control list of an MCP server
// config.
type MCPServerConfigACL struct {
Users []MCPServerConfigUser `json:"users"`
Groups []MCPServerConfigGroup `json:"groups"`
}
// MCPServerConfigUser is a user entry in an MCP server config ACL.
type MCPServerConfigUser struct {
MinimalUser
Role MCPServerConfigRole `json:"role" enums:"read"`
}
// MCPServerConfigGroup is a group entry in an MCP server config ACL.
type MCPServerConfigGroup struct {
Group
Role MCPServerConfigRole `json:"role" enums:"read"`
}
// UpdateMCPServerConfigACLRequest is a sparse update of an MCP server
// config ACL: only the listed principals change, and
// MCPServerConfigRoleDeleted removes an entry.
type UpdateMCPServerConfigACLRequest struct {
UserRoles map[string]MCPServerConfigRole `json:"user_roles,omitempty"`
GroupRoles map[string]MCPServerConfigRole `json:"group_roles,omitempty"`
}
// CreateMCPServerConfigRequest is the request to create a new MCP server config.
type CreateMCPServerConfigRequest struct {
DisplayName string `json:"display_name" validate:"required"`
Slug string `json:"slug" validate:"required"`
Description string `json:"description"`
IconURL string `json:"icon_url"`
Transport string `json:"transport" validate:"required,oneof=streamable_http sse"`
URL string `json:"url" validate:"required,url"`
AuthType string `json:"auth_type" validate:"required,oneof=none oauth2 api_key custom_headers user_oidc"`
OAuth2ClientID string `json:"oauth2_client_id,omitempty"`
OAuth2ClientSecret string `json:"oauth2_client_secret,omitempty"`
OAuth2AuthURL string `json:"oauth2_auth_url,omitempty" validate:"omitempty,url"`
OAuth2TokenURL string `json:"oauth2_token_url,omitempty" validate:"omitempty,url"`
// OAuth2RevocationURL is the provider's RFC 7009 revocation
// endpoint; auto-populated by OAuth2 discovery when omitted.
OAuth2RevocationURL string `json:"oauth2_revocation_url,omitempty" validate:"omitempty,url"`
OAuth2Scopes string `json:"oauth2_scopes,omitempty"`
APIKeyHeader string `json:"api_key_header,omitempty"`
APIKeyValue string `json:"api_key_value,omitempty"`
CustomHeaders map[string]string `json:"custom_headers,omitempty"`
ToolAllowList []string `json:"tool_allow_list,omitempty"`
ToolDenyList []string `json:"tool_deny_list,omitempty"`
Availability string `json:"availability" validate:"required,oneof=force_on default_on default_off"`
Enabled bool `json:"enabled"`
ModelIntent bool `json:"model_intent"`
AllowInPlanMode bool `json:"allow_in_plan_mode"`
// ForwardCoderHeaders, when true, forwards Coder identity
// headers on every outgoing MCP request. See MCPServerConfig.
ForwardCoderHeaders bool `json:"forward_coder_headers"`
// SigningSecret signs forwarded identity headers and request bodies.
// Configure the same secret on the MCP server. It is never returned.
SigningSecret string `json:"signing_secret,omitempty"`
}
// UpdateMCPServerConfigRequest is the request to update an MCP server config.
type UpdateMCPServerConfigRequest struct {
DisplayName *string `json:"display_name,omitempty"`
Slug *string `json:"slug,omitempty"`
Description *string `json:"description,omitempty"`
IconURL *string `json:"icon_url,omitempty"`
Transport *string `json:"transport,omitempty" validate:"omitempty,oneof=streamable_http sse"`
URL *string `json:"url,omitempty" validate:"omitempty,url"`
AuthType *string `json:"auth_type,omitempty" validate:"omitempty,oneof=none oauth2 api_key custom_headers user_oidc"`
OAuth2ClientID *string `json:"oauth2_client_id,omitempty"`
OAuth2ClientSecret *string `json:"oauth2_client_secret,omitempty"`
OAuth2AuthURL *string `json:"oauth2_auth_url,omitempty" validate:"omitempty,url"`
OAuth2TokenURL *string `json:"oauth2_token_url,omitempty" validate:"omitempty,url"`
// OAuth2RevocationURL is validated in the handler because a
// validate tag would reject the pointer to "" that clears it.
OAuth2RevocationURL *string `json:"oauth2_revocation_url,omitempty"`
OAuth2Scopes *string `json:"oauth2_scopes,omitempty"`
APIKeyHeader *string `json:"api_key_header,omitempty"`
APIKeyValue *string `json:"api_key_value,omitempty"`
CustomHeaders *map[string]string `json:"custom_headers,omitempty"`
ToolAllowList *[]string `json:"tool_allow_list,omitempty"`
ToolDenyList *[]string `json:"tool_deny_list,omitempty"`
Availability *string `json:"availability,omitempty" validate:"omitempty,oneof=force_on default_on default_off"`
Enabled *bool `json:"enabled,omitempty"`
ModelIntent *bool `json:"model_intent,omitempty"`
AllowInPlanMode *bool `json:"allow_in_plan_mode,omitempty"`
// ForwardCoderHeaders, when set, updates whether Coder identity
// headers are forwarded on every outgoing MCP request.
ForwardCoderHeaders *bool `json:"forward_coder_headers,omitempty"`
// SigningSecret replaces the shared signing key. Omit to preserve it;
// an empty string clears it. It is never returned.
SigningSecret *string `json:"signing_secret,omitempty"`
}
func (c *Client) MCPServerConfigs(ctx context.Context, organizationID uuid.UUID) ([]MCPServerConfig, error) {
res, err := c.Request(ctx, http.MethodGet, fmt.Sprintf("/api/v2/organizations/%s/mcp-servers", organizationID), nil)
if err != nil {
return nil, err
}
defer res.Body.Close()
if res.StatusCode != http.StatusOK {
return nil, ReadBodyAsError(res)
}
var configs []MCPServerConfig
return configs, ReadBodyAsJSON(res, &configs)
}
func (c *Client) MCPServerConfigByID(ctx context.Context, organizationID, id uuid.UUID) (MCPServerConfig, error) {
res, err := c.Request(ctx, http.MethodGet, fmt.Sprintf("/api/v2/organizations/%s/mcp-servers/%s", organizationID, id), nil)
if err != nil {
return MCPServerConfig{}, err
}
defer res.Body.Close()
if res.StatusCode != http.StatusOK {
return MCPServerConfig{}, ReadBodyAsError(res)
}
var config MCPServerConfig
return config, ReadBodyAsJSON(res, &config)
}
// MCPServerConfigACL returns the resolved ACL of an MCP server config.
func (c *Client) MCPServerConfigACL(ctx context.Context, organizationID, id uuid.UUID) (MCPServerConfigACL, error) {
res, err := c.Request(ctx, http.MethodGet, fmt.Sprintf("/api/v2/organizations/%s/mcp-servers/%s/acl", organizationID, id), nil)
if err != nil {
return MCPServerConfigACL{}, err
}
defer res.Body.Close()
if res.StatusCode != http.StatusOK {
return MCPServerConfigACL{}, ReadBodyAsError(res)
}
var acl MCPServerConfigACL
return acl, ReadBodyAsJSON(res, &acl)
}
// MCPServerConfigACLAvailable returns available users and groups that can be
// assigned to an MCP server config ACL.
func (c *Client) MCPServerConfigACLAvailable(ctx context.Context, organizationID, id uuid.UUID, req UsersRequest) (ACLAvailable, error) {
res, err := c.Request(ctx, http.MethodGet,
fmt.Sprintf("/api/v2/organizations/%s/mcp-servers/%s/acl/available", organizationID, id),
nil,
req.Pagination.asRequestOption(),
req.asRequestOption(),
)
if err != nil {
return ACLAvailable{}, err
}
defer res.Body.Close()
if res.StatusCode != http.StatusOK {
return ACLAvailable{}, ReadBodyAsError(res)
}
var available ACLAvailable
return available, ReadBodyAsJSON(res, &available)
}
// UpdateMCPServerConfigACL applies a sparse ACL update to an MCP server
// config.
func (c *Client) UpdateMCPServerConfigACL(ctx context.Context, organizationID, id uuid.UUID, req UpdateMCPServerConfigACLRequest) error {
res, err := c.Request(ctx, http.MethodPatch, fmt.Sprintf("/api/v2/organizations/%s/mcp-servers/%s/acl", organizationID, id), req)
if err != nil {
return err
}
defer res.Body.Close()
if res.StatusCode != http.StatusNoContent {
return ReadBodyAsError(res)
}
return nil
}
func (c *Client) CreateMCPServerConfig(ctx context.Context, organizationID uuid.UUID, req CreateMCPServerConfigRequest) (MCPServerConfig, error) {
res, err := c.Request(ctx, http.MethodPost, fmt.Sprintf("/api/v2/organizations/%s/mcp-servers", organizationID), req)
if err != nil {
return MCPServerConfig{}, err
}
defer res.Body.Close()
if res.StatusCode != http.StatusCreated {
return MCPServerConfig{}, ReadBodyAsError(res)
}
var config MCPServerConfig
return config, ReadBodyAsJSON(res, &config)
}
func (c *Client) UpdateMCPServerConfig(ctx context.Context, organizationID, id uuid.UUID, req UpdateMCPServerConfigRequest) (MCPServerConfig, error) {
res, err := c.Request(ctx, http.MethodPatch, fmt.Sprintf("/api/v2/organizations/%s/mcp-servers/%s", organizationID, id), req)
if err != nil {
return MCPServerConfig{}, err
}
defer res.Body.Close()
if res.StatusCode != http.StatusOK {
return MCPServerConfig{}, ReadBodyAsError(res)
}
var config MCPServerConfig
return config, ReadBodyAsJSON(res, &config)
}
func (c *Client) DeleteMCPServerConfig(ctx context.Context, organizationID, id uuid.UUID) error {
res, err := c.Request(ctx, http.MethodDelete, fmt.Sprintf("/api/v2/organizations/%s/mcp-servers/%s", organizationID, id), nil)
if err != nil {
return err
}
defer res.Body.Close()
if res.StatusCode != http.StatusNoContent {
return ReadBodyAsError(res)
}
return nil
}