k3s/pkg/server/auth.go

package server

import (
	"net/http"

	"github.com/gorilla/mux"
	"github.com/k3s-io/k3s/pkg/daemons/config"
	"github.com/k3s-io/k3s/pkg/generated/clientset/versioned/scheme"
	"github.com/sirupsen/logrus"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apiserver/pkg/endpoints/handlers/responsewriters"
	"k8s.io/apiserver/pkg/endpoints/request"
)

func hasRole(mustRoles []string, roles []string) bool {
	for _, check := range roles {
		for _, role := range mustRoles {
			if role == check {
				return true
			}
		}
	}
	return false
}

func doAuth(roles []string, serverConfig *config.Control, next http.Handler, rw http.ResponseWriter, req *http.Request) {
	switch {
	case serverConfig == nil:
		logrus.Errorf("Authenticate not initialized: serverConfig is nil")
		unauthorized(rw, req)
		return
	case serverConfig.Runtime.Authenticator == nil:
		logrus.Errorf("Authenticate not initialized: serverConfig.Runtime.Authenticator is nil")
		unauthorized(rw, req)
		return
	}

	resp, ok, err := serverConfig.Runtime.Authenticator.AuthenticateRequest(req)
	if err != nil {
		logrus.Errorf("Failed to authenticate request from %s: %v", req.RemoteAddr, err)
		unauthorized(rw, req)
		return
	}

	if !ok || !hasRole(roles, resp.User.GetGroups()) {
		forbidden(rw, req)
		return
	}

	ctx := request.WithUser(req.Context(), resp.User)
	req = req.WithContext(ctx)
	next.ServeHTTP(rw, req)
}

func authMiddleware(serverConfig *config.Control, roles ...string) mux.MiddlewareFunc {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
			doAuth(roles, serverConfig, next, rw, req)
		})
	}
}

func unauthorized(resp http.ResponseWriter, req *http.Request) {
	responsewriters.ErrorNegotiated(
		&apierrors.StatusError{ErrStatus: metav1.Status{
			Status:  metav1.StatusFailure,
			Code:    http.StatusUnauthorized,
			Reason:  metav1.StatusReasonUnauthorized,
			Message: "not authorized",
		}},
		scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
	)
}

func forbidden(resp http.ResponseWriter, req *http.Request) {
	responsewriters.ErrorNegotiated(
		&apierrors.StatusError{ErrStatus: metav1.Status{
			Status:  metav1.StatusFailure,
			Code:    http.StatusForbidden,
			Reason:  metav1.StatusReasonForbidden,
			Message: "forbidden",
		}},
		scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
	)
}