/*
Copyright 2024 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package auth

import (
	"context"
	_ "embed"
	"fmt"
	"strings"

	g "github.com/onsi/ginkgo/v2"
	o "github.com/onsi/gomega"

	admissionregistrationv1 "k8s.io/api/admissionregistration/v1"
	authenticationv1 "k8s.io/api/authentication/v1"
	v1 "k8s.io/api/core/v1"
	rbacv1 "k8s.io/api/rbac/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apiserver/pkg/authentication/serviceaccount"
	"k8s.io/client-go/kubernetes"
	cgoscheme "k8s.io/client-go/kubernetes/scheme"
	"k8s.io/client-go/rest"
	"k8s.io/kubernetes/test/e2e/framework"
	e2epod "k8s.io/kubernetes/test/e2e/framework/pod"
	imageutils "k8s.io/kubernetes/test/utils/image"
	admissionapi "k8s.io/pod-security-admission/api"
	"k8s.io/utils/ptr"
)

// Embed manifests that we leave as yaml to make it clear to users how to these permissions are created.
// These will match future docs.
var (
	//go:embed e2edata/per_node_validatingadmissionpolicy.yaml
	perNodeCheckValidatingAdmissionPolicy string

	//go:embed e2edata/per_node_validatingadmissionpolicybinding.yaml
	perNodeCheckValidatingAdmissionPolicyBinding string
)

var _ = SIGDescribe("ValidatingAdmissionPolicy", func() {
	defer g.GinkgoRecover()
	f := framework.NewDefaultFramework("node-authn")
	f.NamespacePodSecurityLevel = admissionapi.LevelRestricted

	g.It("can restrict access by-node", func(ctx context.Context) {
		admission := strings.ReplaceAll(perNodeCheckValidatingAdmissionPolicy, "e2e-ns", f.Namespace.Name)
		admissionToCreate := readValidatingAdmissionPolicyV1OrDie([]byte(admission))
		admissionBinding := strings.ReplaceAll(perNodeCheckValidatingAdmissionPolicyBinding, "e2e-ns", f.Namespace.Name)
		admissionBindingToCreate := readValidatingAdmissionPolicyBindingV1OrDie([]byte(admissionBinding))

		saTokenRoleBinding := &rbacv1.RoleBinding{
			ObjectMeta: metav1.ObjectMeta{
				Namespace: f.Namespace.Name,
				Name:      "sa-token",
			},
			Subjects: []rbacv1.Subject{
				{
					Kind:      "ServiceAccount",
					Name:      "default",
					Namespace: f.Namespace.Name,
				},
			},
			RoleRef: rbacv1.RoleRef{
				APIGroup: "rbac.authorization.k8s.io",
				Kind:     "ClusterRole",
				Name:     "edit",
			},
		}

		agnhost := imageutils.GetConfig(imageutils.Agnhost)
		sleeperPod := e2epod.MustMixinRestrictedPodSecurity(&v1.Pod{
			ObjectMeta: metav1.ObjectMeta{
				Namespace: f.Namespace.Name,
				Name:      "sa-token",
			},
			Spec: v1.PodSpec{
				Containers: []v1.Container{
					{
						Name:    "sleeper",
						Image:   agnhost.GetE2EImage(),
						Command: []string{"sleep"},
						Args:    []string{"1200"},
						SecurityContext: &v1.SecurityContext{
							AllowPrivilegeEscalation: ptr.To(false),
							Capabilities: &v1.Capabilities{
								Drop: []v1.Capability{"ALL"},
							},
						},
					},
				},
			},
			Status: v1.PodStatus{},
		})

		// cleanup the ValidatingAdmissionPolicy.

		var err error
		_, err = f.ClientSet.AdmissionregistrationV1().ValidatingAdmissionPolicies().Create(ctx, admissionToCreate, metav1.CreateOptions{})
		framework.ExpectNoError(err)
		g.DeferCleanup(f.ClientSet.AdmissionregistrationV1().ValidatingAdmissionPolicies().Delete, admissionToCreate.Name, metav1.DeleteOptions{})

		_, err = f.ClientSet.AdmissionregistrationV1().ValidatingAdmissionPolicyBindings().Create(ctx, admissionBindingToCreate, metav1.CreateOptions{})
		framework.ExpectNoError(err)
		g.DeferCleanup(f.ClientSet.AdmissionregistrationV1().ValidatingAdmissionPolicyBindings().Delete, admissionBindingToCreate.Name, metav1.DeleteOptions{})

		// create permissions that will allow unrestricted access to mutate configmaps in this namespace.
		// We limited these permissions in the step above.
		// This means the admission policy must fail closed or permissions will be too broad.
		_, err = f.ClientSet.RbacV1().RoleBindings(f.Namespace.Name).Create(ctx, saTokenRoleBinding, metav1.CreateOptions{})
		framework.ExpectNoError(err)

		// run an actual pod to prove that the token is injected, not just creatable via the API
		actualPod, err := f.ClientSet.CoreV1().Pods(f.Namespace.Name).Create(ctx, sleeperPod, metav1.CreateOptions{})
		framework.ExpectNoError(err)
		err = e2epod.WaitForPodNameRunningInNamespace(ctx, f.ClientSet, actualPod.Name, actualPod.Namespace)
		framework.ExpectNoError(err)
		// need the pod that contains the node name
		actualPod, err = f.ClientSet.CoreV1().Pods(f.Namespace.Name).Get(ctx, actualPod.Name, metav1.GetOptions{})
		framework.ExpectNoError(err)

		// get the actual projected token from the pod.
		nodeScopedSAToken, stderr, err := e2epod.ExecWithOptionsContext(ctx, f, e2epod.ExecOptions{
			Command:            []string{"cat", "/var/run/secrets/kubernetes.io/serviceaccount/token"},
			Namespace:          actualPod.Namespace,
			PodName:            actualPod.Name,
			ContainerName:      actualPod.Spec.Containers[0].Name,
			CaptureStdout:      true,
			CaptureStderr:      true,
			PreserveWhitespace: true,
		})
		framework.ExpectNoError(err)
		o.Expect(stderr).To(o.BeEmpty(), "stderr from cat")

		// make a kubeconfig with the token and confirm the kube-apiserver has the expected claims
		nodeScopedClientConfig := rest.AnonymousClientConfig(f.ClientConfig())
		nodeScopedClientConfig.BearerToken = nodeScopedSAToken
		nodeScopedClient, err := kubernetes.NewForConfig(nodeScopedClientConfig)
		framework.ExpectNoError(err)
		saUser, err := nodeScopedClient.AuthenticationV1().SelfSubjectReviews().Create(ctx, &authenticationv1.SelfSubjectReview{}, metav1.CreateOptions{})
		framework.ExpectNoError(err)
		expectedUser := serviceaccount.MakeUsername(f.Namespace.Name, "default")
		o.Expect(saUser.Status.UserInfo.Username).To(o.Equal(expectedUser))
		expectedNode := authenticationv1.ExtraValue([]string{actualPod.Spec.NodeName})
		o.Expect(saUser.Status.UserInfo.Extra["authentication.kubernetes.io/node-name"]).To(o.Equal(expectedNode))

		allowedConfigMap := &v1.ConfigMap{
			ObjectMeta: metav1.ObjectMeta{
				Namespace: f.Namespace.Name,
				Name:      actualPod.Spec.NodeName,
			},
		}
		disallowedConfigMap := &v1.ConfigMap{
			ObjectMeta: metav1.ObjectMeta{
				Namespace: f.Namespace.Name,
				Name:      "unlikely-node",
			},
		}
		disallowedMessage := fmt.Sprintf("this user running on node '%s' may not modify ConfigMap '%s' because the name does not match the node name", actualPod.Spec.NodeName, disallowedConfigMap.Name)

		actualAllowedConfigMap, err := nodeScopedClient.CoreV1().ConfigMaps(f.Namespace.Name).Create(ctx, allowedConfigMap, metav1.CreateOptions{})
		framework.ExpectNoError(err)
		_, err = nodeScopedClient.CoreV1().ConfigMaps(f.Namespace.Name).Create(ctx, disallowedConfigMap, metav1.CreateOptions{})
		o.Expect(err).To(o.HaveOccurred())
		o.Expect(err.Error()).To(o.ContainSubstring(disallowedMessage))

		// now create so we can see the update cases
		actualDisallowedConfigMap, err := f.ClientSet.CoreV1().ConfigMaps(f.Namespace.Name).Create(ctx, disallowedConfigMap, metav1.CreateOptions{})
		framework.ExpectNoError(err)

		actualAllowedConfigMap, err = nodeScopedClient.CoreV1().ConfigMaps(f.Namespace.Name).Update(ctx, actualAllowedConfigMap, metav1.UpdateOptions{})
		framework.ExpectNoError(err)
		_, err = nodeScopedClient.CoreV1().ConfigMaps(f.Namespace.Name).Update(ctx, actualDisallowedConfigMap, metav1.UpdateOptions{})
		o.Expect(err).To(o.HaveOccurred())
		o.Expect(err.Error()).To(o.ContainSubstring(disallowedMessage))

		err = nodeScopedClient.CoreV1().ConfigMaps(f.Namespace.Name).Delete(ctx, actualAllowedConfigMap.Name, metav1.DeleteOptions{})
		framework.ExpectNoError(err)
		err = nodeScopedClient.CoreV1().ConfigMaps(f.Namespace.Name).Delete(ctx, actualDisallowedConfigMap.Name, metav1.DeleteOptions{})
		o.Expect(err).To(o.HaveOccurred())
		o.Expect(err.Error()).To(o.ContainSubstring(disallowedMessage))

		// recreate the allowedConfigMap and then do a delete collection
		_, err = nodeScopedClient.CoreV1().ConfigMaps(f.Namespace.Name).Create(ctx, allowedConfigMap, metav1.CreateOptions{})
		framework.ExpectNoError(err)
		err = nodeScopedClient.CoreV1().ConfigMaps(f.Namespace.Name).DeleteCollection(ctx, metav1.DeleteOptions{}, metav1.ListOptions{})
		o.Expect(err).To(o.HaveOccurred())
		// Delete collection can happen in random/racy orders.  We'll match on everything except the name
		disallowedAnyNameMessage := fmt.Sprintf("this user running on node '%s' may not modify ConfigMap .* because the name does not match the node name", actualPod.Spec.NodeName)
		o.Expect(err.Error()).To(o.MatchRegexp(disallowedAnyNameMessage))

		// ensure that if the node claim is missing from the restricted service-account user, we reject the request
		tokenRequest := &authenticationv1.TokenRequest{
			Spec: authenticationv1.TokenRequestSpec{
				ExpirationSeconds: ptr.To[int64](600),
			},
		}
		tokenRequestResponse, err := f.ClientSet.CoreV1().ServiceAccounts(f.Namespace.Name).CreateToken(ctx, "default", tokenRequest, metav1.CreateOptions{})
		framework.ExpectNoError(err)
		serviceAccountConfigWithoutNodeClaim := rest.AnonymousClientConfig(f.ClientConfig())
		serviceAccountConfigWithoutNodeClaim.BearerToken = tokenRequestResponse.Status.Token
		serviceAccountClientWithoutNodeClaim, err := kubernetes.NewForConfig(serviceAccountConfigWithoutNodeClaim)
		framework.ExpectNoError(err)
		// now confirm this token lacks a node name claim.
		selfSubjectResults, err := serviceAccountClientWithoutNodeClaim.AuthenticationV1().SelfSubjectReviews().Create(ctx, &authenticationv1.SelfSubjectReview{}, metav1.CreateOptions{})
		framework.Logf("Token: %q expires at %v", serviceAccountConfigWithoutNodeClaim.BearerToken, tokenRequestResponse.Status.ExpirationTimestamp)
		framework.ExpectNoError(err)
		o.Expect(selfSubjectResults.Status.UserInfo.Extra["authentication.kubernetes.io/node-name"]).To(o.BeEmpty())

		noNodeAssociationMessage := "no node association found for user, this user must run in a pod on a node and ServiceAccountTokenPodNodeInfo must be enabled"
		_, err = serviceAccountClientWithoutNodeClaim.CoreV1().ConfigMaps(f.Namespace.Name).Create(ctx, actualDisallowedConfigMap, metav1.CreateOptions{})
		o.Expect(err).To(o.HaveOccurred())
		o.Expect(err.Error()).To(o.ContainSubstring(noNodeAssociationMessage))
		_, err = serviceAccountClientWithoutNodeClaim.CoreV1().ConfigMaps(f.Namespace.Name).Create(ctx, actualAllowedConfigMap, metav1.CreateOptions{})
		o.Expect(err).To(o.HaveOccurred())
		o.Expect(err.Error()).To(o.ContainSubstring(noNodeAssociationMessage))
		err = serviceAccountClientWithoutNodeClaim.CoreV1().ConfigMaps(f.Namespace.Name).Delete(ctx, actualDisallowedConfigMap.Name, metav1.DeleteOptions{})
		o.Expect(err).To(o.HaveOccurred())
		o.Expect(err.Error()).To(o.ContainSubstring(noNodeAssociationMessage))
	})
})

func readValidatingAdmissionPolicyV1OrDie(objBytes []byte) *admissionregistrationv1.ValidatingAdmissionPolicy {
	requiredObj, err := runtime.Decode(cgoscheme.Codecs.UniversalDecoder(admissionregistrationv1.SchemeGroupVersion), objBytes)
	if err != nil {
		panic(err)
	}
	return requiredObj.(*admissionregistrationv1.ValidatingAdmissionPolicy)
}

func readValidatingAdmissionPolicyBindingV1OrDie(objBytes []byte) *admissionregistrationv1.ValidatingAdmissionPolicyBinding {
	requiredObj, err := runtime.Decode(cgoscheme.Codecs.UniversalDecoder(admissionregistrationv1.SchemeGroupVersion), objBytes)
	if err != nil {
		panic(err)
	}
	return requiredObj.(*admissionregistrationv1.ValidatingAdmissionPolicyBinding)
}