chore: CORs option for yarn dev server (#7630)

Emyrk · web-flow · commit 5d711fc95add · 2023-05-22T20:02:39.000+02:00
* chore: Yarn dev servers require CORs headers for external proxies

Adds a flag to set CORs headers to `*` for yarn dev servers
diff --git a/coderd/apidoc/docs.go b/coderd/apidoc/docs.go
diff --git a/coderd/apidoc/swagger.json b/coderd/apidoc/swagger.json
diff --git a/coderd/coderd.go b/coderd/coderd.go
@@ -393,8 +393,10 @@ func New(options *Options) *API {
 
 	derpHandler := derphttp.Handler(api.DERPServer)
 	derpHandler, api.derpCloseFunc = tailnet.WithWebsocketSupport(api.DERPServer, derpHandler)
+	cors := httpmw.Cors(options.DeploymentValues.Dangerous.AllowAllCors.Value())
 
 	r.Use(
+		cors,
 		httpmw.Recover(api.Logger),
 		tracing.StatusWriterMiddleware,
 		tracing.Middleware(api.TracerProvider),
@@ -799,6 +801,10 @@ func New(options *Options) *API {
 	// Add CSP headers to all static assets and pages. CSP headers only affect
 	// browsers, so these don't make sense on api routes.
 	cspMW := httpmw.CSPHeaders(func() []string {
+		if api.DeploymentValues.Dangerous.AllowAllCors {
+			// In this mode, allow all external requests
+			return []string{"*"}
+		}
 		if f := api.WorkspaceProxyHostsFn.Load(); f != nil {
 			return (*f)()
 		}
@@ -813,7 +819,7 @@ func New(options *Options) *API {
 	// This is the only route we add before all the middleware.
 	// We want to time the latency of the request, so any middleware will
 	// interfere with that timing.
-	rootRouter.Get("/latency-check", LatencyCheck(api.AccessURL))
+	rootRouter.Get("/latency-check", cors(LatencyCheck(options.DeploymentValues.Dangerous.AllowAllCors.Value(), api.AccessURL)).ServeHTTP)
 	rootRouter.Mount("/", r)
 	api.RootHandler = rootRouter
 
diff --git a/coderd/httpmw/cors.go b/coderd/httpmw/cors.go
@@ -0,0 +1,27 @@
+package httpmw
+
+import (
+	"net/http"
+
+	"github.com/go-chi/cors"
+)
+
+//nolint:revive
+func Cors(allowAll bool, origins ...string) func(next http.Handler) http.Handler {
+	if len(origins) == 0 {
+		// The default behavior is '*', so putting the empty string defaults to
+		// the secure behavior of blocking CORs requests.
+		origins = []string{""}
+	}
+	if allowAll {
+		origins = []string{"*"}
+	}
+	return cors.Handler(cors.Options{
+		AllowedOrigins: origins,
+		// We only need GET for latency requests
+		AllowedMethods: []string{http.MethodOptions, http.MethodGet},
+		AllowedHeaders: []string{"Accept", "Content-Type", "X-LATENCY-CHECK", "X-CSRF-TOKEN"},
+		// Do not send any cookies
+		AllowCredentials: false,
+	})
+}
diff --git a/coderd/httpmw/csp.go b/coderd/httpmw/csp.go
@@ -103,6 +103,11 @@ func CSPHeaders(websocketHosts func() []string) func(next http.Handler) http.Han
 			extraConnect := websocketHosts()
 			if len(extraConnect) > 0 {
 				for _, extraHost := range extraConnect {
+					if extraHost == "*" {
+						// '*' means all
+						cspSrcs.Append(cspDirectiveConnectSrc, "*")
+						continue
+					}
 					cspSrcs.Append(cspDirectiveConnectSrc, fmt.Sprintf("wss://%[1]s ws://%[1]s", extraHost))
 					// We also require this to make http/https requests to the workspace proxy for latency checking.
 					cspSrcs.Append(cspDirectiveConnectSrc, fmt.Sprintf("https://%[1]s http://%[1]s", extraHost))
diff --git a/coderd/latencycheck.go b/coderd/latencycheck.go
@@ -6,14 +6,22 @@ import (
 	"strings"
 )
 
-func LatencyCheck(allowedOrigins ...*url.URL) http.HandlerFunc {
+// LatencyCheck is an endpoint for the web ui to measure latency with.
+// allowAll allows any Origin to get timing information. The allowAll should
+// only be set in dev modes.
+//
+//nolint:revive
+func LatencyCheck(allowAll bool, allowedOrigins ...*url.URL) http.HandlerFunc {
 	allowed := make([]string, 0, len(allowedOrigins))
 	for _, origin := range allowedOrigins {
 		// Allow the origin without a path
 		tmp := *origin
 		tmp.Path = ""
 		allowed = append(allowed, strings.TrimSuffix(origin.String(), "/"))
 	}
+	if allowAll {
+		allowed = append(allowed, "*")
+	}
 	origins := strings.Join(allowed, ",")
 	return func(rw http.ResponseWriter, r *http.Request) {
 		// Allowing timing information to be shared. This allows the browser
diff --git a/codersdk/deployment.go b/codersdk/deployment.go
@@ -330,6 +330,7 @@ type LoggingConfig struct {
 type DangerousConfig struct {
 	AllowPathAppSharing         clibase.Bool `json:"allow_path_app_sharing" typescript:",notnull"`
 	AllowPathAppSiteOwnerAccess clibase.Bool `json:"allow_path_app_site_owner_access" typescript:",notnull"`
+	AllowAllCors                clibase.Bool `json:"allow_all_cors" typescript:",notnull"`
 }
 
 const (
@@ -1167,6 +1168,16 @@ when required by your organization's security policy.`,
 			Annotations: clibase.Annotations{}.Mark(annotationExternalProxies, "true"),
 		},
 		// ☢️ Dangerous settings
+		{
+			Name:        "DANGEROUS: Allow all CORs requests",
+			Description: "For security reasons, CORs requests are blocked. If external requests are required, setting this to true will set all cors headers as '*'. This should never be used in production.",
+			Flag:        "dangerous-allow-cors-requests",
+			Env:         "CODER_DANGEROUS_ALLOW_CORS_REQUESTS",
+			Hidden:      true, // Hidden, should only be used by yarn dev server
+			Value:       &c.Dangerous.AllowAllCors,
+			Group:       &deploymentGroupDangerous,
+			Annotations: clibase.Annotations{}.Mark(annotationExternalProxies, "true"),
+		},
 		{
 			Name:        "DANGEROUS: Allow Path App Sharing",
 			Description: "Allow workspace apps that are not served from subdomains to be shared. Path-based app sharing is DISABLED by default for security purposes. Path-based apps can make requests to the Coder API and pose a security risk when the workspace serves malicious JavaScript. Path-based apps can be disabled entirely with --disable-path-apps for further security.",
diff --git a/docs/api/general.md b/docs/api/general.md
@@ -161,6 +161,7 @@ curl -X GET http://coder-server:8080/api/v2/deployment/config \
       "sshconfigOptions": ["string"]
     },
     "dangerous": {
+      "allow_all_cors": true,
       "allow_path_app_sharing": true,
       "allow_path_app_site_owner_access": true
     },
diff --git a/docs/api/schemas.md b/docs/api/schemas.md
@@ -1800,6 +1800,7 @@ CreateParameterRequest is a structure used to create a new parameter value for a
 
 ```json
 {
+  "allow_all_cors": true,
   "allow_path_app_sharing": true,
   "allow_path_app_site_owner_access": true
 }
@@ -1809,6 +1810,7 @@ CreateParameterRequest is a structure used to create a new parameter value for a
 
 | Name                               | Type    | Required | Restrictions | Description |
 | ---------------------------------- | ------- | -------- | ------------ | ----------- |
+| `allow_all_cors`                   | boolean | false    |              |             |
 | `allow_path_app_sharing`           | boolean | false    |              |             |
 | `allow_path_app_site_owner_access` | boolean | false    |              |             |
 
@@ -1857,6 +1859,7 @@ CreateParameterRequest is a structure used to create a new parameter value for a
       "sshconfigOptions": ["string"]
     },
     "dangerous": {
+      "allow_all_cors": true,
       "allow_path_app_sharing": true,
       "allow_path_app_site_owner_access": true
     },
@@ -2201,6 +2204,7 @@ CreateParameterRequest is a structure used to create a new parameter value for a
     "sshconfigOptions": ["string"]
   },
   "dangerous": {
+    "allow_all_cors": true,
     "allow_path_app_sharing": true,
     "allow_path_app_site_owner_access": true
   },
diff --git a/enterprise/cli/proxyserver.go b/enterprise/cli/proxyserver.go
@@ -245,6 +245,7 @@ func (*RootCmd) proxyServer() *clibase.Cmd {
 				SecureAuthCookie:   cfg.SecureAuthCookie.Value(),
 				DisablePathApps:    cfg.DisablePathApps.Value(),
 				ProxySessionToken:  proxySessionToken.Value(),
+				AllowAllCors:       cfg.Dangerous.AllowAllCors.Value(),
 			})
 			if err != nil {
 				return xerrors.Errorf("create workspace proxy: %w", err)
diff --git a/enterprise/wsproxy/wsproxy.go b/enterprise/wsproxy/wsproxy.go
@@ -11,7 +11,6 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
-	"github.com/go-chi/cors"
 	"github.com/google/uuid"
 	"github.com/prometheus/client_golang/prometheus"
 	"go.opentelemetry.io/otel/trace"
@@ -61,6 +60,10 @@ type Options struct {
 	DisablePathApps  bool
 
 	ProxySessionToken string
+	// AllowAllCors will set all CORs headers to '*'.
+	// By default, CORs is set to accept external requests
+	// from the dashboardURL. This should only be used in development.
+	AllowAllCors bool
 }
 
 func (o *Options) Validate() error {
@@ -189,18 +192,7 @@ func New(ctx context.Context, opts *Options) (*Server, error) {
 
 	// The primary coderd dashboard needs to make some GET requests to
 	// the workspace proxies to check latency.
-	corsMW := cors.Handler(cors.Options{
-		AllowedOrigins: []string{
-			// Allow the dashboard to make requests to the proxy for latency
-			// checks.
-			opts.DashboardURL.String(),
-		},
-		// Only allow GET requests for latency checks.
-		AllowedMethods: []string{http.MethodOptions, http.MethodGet},
-		AllowedHeaders: []string{"Accept", "Content-Type", "X-LATENCY-CHECK", "X-CSRF-TOKEN"},
-		// Do not send any cookies
-		AllowCredentials: false,
-	})
+	corsMW := httpmw.Cors(opts.AllowAllCors, opts.DashboardURL.String())
 
 	// Routes
 	apiRateLimiter := httpmw.RateLimit(opts.APIRateLimit, time.Minute)
@@ -266,7 +258,7 @@ func New(ctx context.Context, opts *Options) (*Server, error) {
 	// See coderd/coderd.go for why we need this.
 	rootRouter := chi.NewRouter()
 	// Make sure to add the cors middleware to the latency check route.
-	rootRouter.Get("/latency-check", corsMW(coderd.LatencyCheck(s.DashboardURL, s.AppServer.AccessURL)).ServeHTTP)
+	rootRouter.Get("/latency-check", corsMW(coderd.LatencyCheck(opts.AllowAllCors, s.DashboardURL, s.AppServer.AccessURL)).ServeHTTP)
 	rootRouter.Mount("/", r)
 	s.Handler = rootRouter
 
diff --git a/scripts/develop.sh b/scripts/develop.sh
@@ -131,7 +131,7 @@ fatal() {
 	trap 'fatal "Script encountered an error"' ERR
 
 	cdroot
-	start_cmd API "" "${CODER_DEV_SHIM}" server --http-address 0.0.0.0:3000 --swagger-enable --access-url "http://127.0.0.1:3000" --experiments "*" "$@"
+	start_cmd API "" "${CODER_DEV_SHIM}" server --http-address 0.0.0.0:3000 --swagger-enable --access-url "http://127.0.0.1:3000" --dangerous-allow-cors-requests=true --experiments "*" "$@"
 
 	echo '== Waiting for Coder to become ready'
 	# Start the timeout in the background so interrupting this script
@@ -185,7 +185,7 @@ fatal() {
 			# Create the proxy
 			proxy_session_token=$("${CODER_DEV_SHIM}" wsproxy create --name=local-proxy --display-name="Local Proxy" --icon="/emojis/1f4bb.png" --only-token)
 			# Start the proxy
-			start_cmd PROXY "" "${CODER_DEV_SHIM}" wsproxy server --http-address=localhost:3010 --proxy-session-token="${proxy_session_token}" --primary-access-url=http://localhost:3000
+			start_cmd PROXY "" "${CODER_DEV_SHIM}" wsproxy server --dangerous-allow-cors-requests=true --http-address=localhost:3010 --proxy-session-token="${proxy_session_token}" --primary-access-url=http://localhost:3000
 		) || echo "Failed to create workspace proxy. No workspace proxy created."
 	fi
 
diff --git a/site/src/api/typesGenerated.ts b/site/src/api/typesGenerated.ts
@@ -313,6 +313,7 @@ export interface DERPServerConfig {
 export interface DangerousConfig {
   readonly allow_path_app_sharing: boolean
   readonly allow_path_app_site_owner_access: boolean
+  readonly allow_all_cors: boolean
 }
 
 // From codersdk/deployment.go
