Plugins: Make proxy endpoints not leak sensitive HTTP headers

Fixes CVE-2022-31130

(cherry picked from commit 40b319d3d6a9945c05709ce8d4679407f6ccadf0)

Author: marefr

pkg/api/plugin_resource.go

@@ -15,6 +15,7 @@ import (
 
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/plugins/backendplugin"
+	"github.com/grafana/grafana/pkg/services/contexthandler"
 	"github.com/grafana/grafana/pkg/services/datasources"
 	"github.com/grafana/grafana/pkg/util/proxyutil"
 	"github.com/grafana/grafana/pkg/web"
@@ -118,6 +119,14 @@ func (hs *HTTPServer) makePluginResourceRequest(w http.ResponseWriter, req *http
 			hs.log.Warn("failed to unpack JSONData in datasource instance settings", "err", err)
 		}
 	}
+
+	list := contexthandler.AuthHTTPHeaderListFromContext(req.Context())
+	if list != nil {
+		for _, name := range list.Items {
+			req.Header.Del(name)
+		}
+	}
+
 	proxyutil.ClearCookieHeader(req, keepCookieModel.KeepCookies)
 	proxyutil.PrepareProxyRequest(req)
 

pkg/api/plugins_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/grafana/grafana/pkg/infra/log/logtest"
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/plugins"
+	"github.com/grafana/grafana/pkg/services/contexthandler"
 	"github.com/grafana/grafana/pkg/services/quota/quotatest"
 	"github.com/grafana/grafana/pkg/setting"
 	"github.com/grafana/grafana/pkg/web/webtest"
@@ -271,6 +272,12 @@ func TestMakePluginResourceRequest(t *testing.T) {
 		pluginClient: pluginClient,
 	}
 	req := httptest.NewRequest(http.MethodGet, "/", nil)
+
+	const customHeader = "X-CUSTOM"
+	req.Header.Set(customHeader, "val")
+	ctx := contexthandler.WithAuthHTTPHeader(req.Context(), customHeader)
+	req = req.WithContext(ctx)
+
 	resp := httptest.NewRecorder()
 	pCtx := backend.PluginContext{}
 	err := hs.makePluginResourceRequest(resp, req, pCtx)
@@ -283,6 +290,7 @@ func TestMakePluginResourceRequest(t *testing.T) {
 	}
 
 	require.Equal(t, "sandbox", resp.Header().Get("Content-Security-Policy"))
+	require.Empty(t, req.Header.Get(customHeader))
 }
 
 func callGetPluginAsset(sc *scenarioContext) {

pkg/middleware/middleware_basic_auth_test.go

@@ -37,6 +37,9 @@ func TestMiddlewareBasicAuth(t *testing.T) {
 		assert.True(t, sc.context.IsSignedIn)
 		assert.Equal(t, orgID, sc.context.OrgId)
 		assert.Equal(t, models.ROLE_EDITOR, sc.context.OrgRole)
+		list := contexthandler.AuthHTTPHeaderListFromContext(sc.context.Req.Context())
+		require.NotNil(t, list)
+		require.EqualValues(t, []string{"Authorization"}, list.Items)
 	}, configure)
 
 	middlewareScenario(t, "Handle auth", func(t *testing.T, sc *scenarioContext) {
@@ -70,6 +73,9 @@ func TestMiddlewareBasicAuth(t *testing.T) {
 
 		assert.True(t, sc.context.IsSignedIn)
 		assert.Equal(t, id, sc.context.UserId)
+		list := contexthandler.AuthHTTPHeaderListFromContext(sc.context.Req.Context())
+		require.NotNil(t, list)
+		require.EqualValues(t, []string{"Authorization"}, list.Items)
 	}, configure)
 
 	middlewareScenario(t, "Should return error if user is not found", func(t *testing.T, sc *scenarioContext) {

pkg/middleware/middleware_jwt_auth_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/services/contexthandler"
@@ -55,6 +56,9 @@ func TestMiddlewareJWTAuth(t *testing.T) {
 		assert.Equal(t, orgID, sc.context.OrgId)
 		assert.Equal(t, id, sc.context.UserId)
 		assert.Equal(t, myUsername, sc.context.Login)
+		list := contexthandler.AuthHTTPHeaderListFromContext(sc.context.Req.Context())
+		require.NotNil(t, list)
+		require.EqualValues(t, []string{sc.cfg.JWTAuthHeaderName}, list.Items)
 	}, configure, configureUsernameClaim)
 
 	middlewareScenario(t, "Valid token with valid email claim", func(t *testing.T, sc *scenarioContext) {

pkg/middleware/middleware_test.go

@@ -396,6 +396,11 @@ func TestMiddlewareContext(t *testing.T) {
 			assert.True(t, sc.context.IsSignedIn)
 			assert.Equal(t, userID, sc.context.UserId)
 			assert.Equal(t, orgID, sc.context.OrgId)
+			list := contexthandler.AuthHTTPHeaderListFromContext(sc.context.Req.Context())
+			require.NotNil(t, list)
+			require.Contains(t, list.Items, sc.cfg.AuthProxyHeaderName)
+			require.Contains(t, list.Items, "X-WEBAUTH-GROUPS")
+			require.Contains(t, list.Items, "X-WEBAUTH-ROLE")
 		}, func(cfg *setting.Cfg) {
 			configure(cfg)
 			cfg.LDAPEnabled = false

pkg/services/contexthandler/auth_jwt.go

@@ -99,6 +99,9 @@ func (h *ContextHandler) initContextWithJWT(ctx *models.ReqContext, orgId int64)
 		return true
 	}
 
+	newCtx := WithAuthHTTPHeader(ctx.Req.Context(), h.Cfg.JWTAuthHeaderName)
+	*ctx.Req = *ctx.Req.WithContext(newCtx)
+
 	ctx.SignedInUser = query.Result
 	ctx.IsSignedIn = true
 

pkg/services/contexthandler/contexthandler.go

@@ -244,6 +244,9 @@ func (h *ContextHandler) initContextWithAPIKey(reqContext *models.ReqContext) bo
 	_, span := h.tracer.Start(reqContext.Req.Context(), "initContextWithAPIKey")
 	defer span.End()
 
+	ctx := WithAuthHTTPHeader(reqContext.Req.Context(), "Authorization")
+	*reqContext.Req = *reqContext.Req.WithContext(ctx)
+
 	var (
 		apikey *models.ApiKey
 		errKey error
@@ -326,7 +329,7 @@ func (h *ContextHandler) initContextWithBasicAuth(reqContext *models.ReqContext,
 		return false
 	}
 
-	ctx, span := h.tracer.Start(reqContext.Req.Context(), "initContextWithBasicAuth")
+	_, span := h.tracer.Start(reqContext.Req.Context(), "initContextWithBasicAuth")
 	defer span.End()
 
 	username, password, err := util.DecodeBasicAuthHeader(header)
@@ -335,12 +338,15 @@ func (h *ContextHandler) initContextWithBasicAuth(reqContext *models.ReqContext,
 		return true
 	}
 
+	ctx := WithAuthHTTPHeader(reqContext.Req.Context(), "Authorization")
+	*reqContext.Req = *reqContext.Req.WithContext(ctx)
+
 	authQuery := models.LoginUserQuery{
 		Username: username,
 		Password: password,
 		Cfg:      h.Cfg,
 	}
-	if err := h.authenticator.AuthenticateUser(reqContext.Req.Context(), &authQuery); err != nil {
+	if err := h.authenticator.AuthenticateUser(ctx, &authQuery); err != nil {
 		reqContext.Logger.Debug(
 			"Failed to authorize the user",
 			"username", username,
@@ -571,6 +577,15 @@ func (h *ContextHandler) initContextWithAuthProxy(reqContext *models.ReqContext,
 
 	logger.Debug("Successfully got user info", "userID", user.UserId, "username", user.Login)
 
+	ctx := WithAuthHTTPHeader(reqContext.Req.Context(), h.Cfg.AuthProxyHeaderName)
+	for _, header := range h.Cfg.AuthProxyHeaders {
+		if header != "" {
+			ctx = WithAuthHTTPHeader(ctx, header)
+		}
+	}
+
+	*reqContext.Req = *reqContext.Req.WithContext(ctx)
+
 	// Add user info to context
 	reqContext.SignedInUser = user
 	reqContext.IsSignedIn = true
@@ -590,3 +605,38 @@ func (h *ContextHandler) initContextWithAuthProxy(reqContext *models.ReqContext,
 
 	return true
 }
+
+type authHTTPHeaderListContextKey struct{}
+
+var authHTTPHeaderListKey = authHTTPHeaderListContextKey{}
+
+// AuthHTTPHeaderList used to record HTTP headers that being when verifying authentication
+// of an incoming HTTP request.
+type AuthHTTPHeaderList struct {
+	Items []string
+}
+
+// WithAuthHTTPHeader returns a copy of parent in which the named HTTP header will be included
+// and later retrievable by AuthHTTPHeaderListFromContext.
+func WithAuthHTTPHeader(parent context.Context, name string) context.Context {
+	list := AuthHTTPHeaderListFromContext(parent)
+
+	if list == nil {
+		list = &AuthHTTPHeaderList{
+			Items: []string{},
+		}
+	}
+
+	list.Items = append(list.Items, name)
+
+	return context.WithValue(parent, authHTTPHeaderListKey, list)
+}
+
+// AuthHTTPHeaderListFromContext returns the AuthHTTPHeaderList in a context.Context, if any,
+// and will include any HTTP headers used when verifying authentication of an incoming HTTP request.
+func AuthHTTPHeaderListFromContext(c context.Context) *AuthHTTPHeaderList {
+	if list, ok := c.Value(authHTTPHeaderListKey).(*AuthHTTPHeaderList); ok {
+		return list
+	}
+	return nil
+}

pkg/util/proxyutil/reverse_proxy.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	glog "github.com/grafana/grafana/pkg/infra/log"
+	"github.com/grafana/grafana/pkg/services/contexthandler"
 )
 
 // StatusClientClosedRequest A non-standard status code introduced by nginx
@@ -66,6 +67,13 @@ func NewReverseProxy(logger glog.Logger, director func(*http.Request), opts ...R
 // wrapDirector wraps a director and adds additional functionality.
 func wrapDirector(d func(*http.Request)) func(req *http.Request) {
 	return func(req *http.Request) {
+		list := contexthandler.AuthHTTPHeaderListFromContext(req.Context())
+		if list != nil {
+			for _, name := range list.Items {
+				req.Header.Del(name)
+			}
+		}
+
 		d(req)
 		PrepareProxyRequest(req)
 

pkg/util/proxyutil/reverse_proxy_test.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/grafana/grafana/pkg/infra/log"
+	"github.com/grafana/grafana/pkg/services/contexthandler"
 	"github.com/stretchr/testify/require"
 )
 
@@ -30,6 +31,11 @@ func TestReverseProxy(t *testing.T) {
 		req.Header.Set("Referer", "https://test.com/api")
 		req.RemoteAddr = "10.0.0.1"
 
+		const customHeader = "X-CUSTOM"
+		req.Header.Set(customHeader, "val")
+		ctx := contexthandler.WithAuthHTTPHeader(req.Context(), customHeader)
+		req = req.WithContext(ctx)
+
 		rp := NewReverseProxy(log.New("test"), func(req *http.Request) {
 			req.Header.Set("X-KEY", "value")
 		})
@@ -49,6 +55,7 @@ func TestReverseProxy(t *testing.T) {
 		require.Empty(t, resp.Cookies())
 		require.Equal(t, "sandbox", resp.Header.Get("Content-Security-Policy"))
 		require.NoError(t, resp.Body.Close())
+		require.Empty(t, actualReq.Header.Get(customHeader))
 	})
 
 	t.Run("When proxying a request using WithModifyResponse should call it before default ModifyResponse func", func(t *testing.T) {