Lightweight Kubernetes
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package server
import (
"context"
"crypto/rand"
"encoding/base64"
"encoding/json"
"fmt"
"io"
"math/big"
"net/http"
"os"
"strings"
"time"
"github.com/k3s-io/k3s/pkg/cluster"
"github.com/k3s-io/k3s/pkg/daemons/config"
"github.com/k3s-io/k3s/pkg/secretsencrypt"
"github.com/rancher/wrangler/pkg/generated/controllers/core"
"github.com/sirupsen/logrus"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/labels"
apiserverconfigv1 "k8s.io/apiserver/pkg/apis/config/v1"
"k8s.io/utils/pointer"
)
const aescbcKeySize = 32
type EncryptionState struct {
Stage string `json:"stage"`
ActiveKey string `json:"activekey"`
Enable *bool `json:"enable,omitempty"`
HashMatch bool `json:"hashmatch,omitempty"`
HashError string `json:"hasherror,omitempty"`
InactiveKeys []string `json:"inactivekeys,omitempty"`
}
type EncryptionRequest struct {
Stage *string `json:"stage,omitempty"`
Enable *bool `json:"enable,omitempty"`
Force bool `json:"force"`
Skip bool `json:"skip"`
}
func getEncryptionRequest(req *http.Request) (EncryptionRequest, error) {
b, err := io.ReadAll(req.Body)
if err != nil {
return EncryptionRequest{}, err
}
result := EncryptionRequest{}
err = json.Unmarshal(b, &result)
return result, err
}
func encryptionStatusHandler(server *config.Control) http.Handler {
return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
if req.TLS == nil {
resp.WriteHeader(http.StatusNotFound)
return
}
status, err := encryptionStatus(server)
if err != nil {
genErrorMessage(resp, http.StatusInternalServerError, err, "secrets-encrypt")
return
}
b, err := json.Marshal(status)
if err != nil {
genErrorMessage(resp, http.StatusInternalServerError, err, "secrets-encrypt")
return
}
resp.Write(b)
})
}
func encryptionStatus(server *config.Control) (EncryptionState, error) {
state := EncryptionState{}
providers, err := secretsencrypt.GetEncryptionProviders(server.Runtime)
if os.IsNotExist(err) {
return state, nil
} else if err != nil {
return state, err
}
if providers[1].Identity != nil && providers[0].AESCBC != nil {
state.Enable = pointer.Bool(true)
} else if providers[0].Identity != nil && providers[1].AESCBC != nil || !server.EncryptSecrets {
state.Enable = pointer.Bool(false)
}
if err := verifyEncryptionHashAnnotation(server.Runtime, server.Runtime.Core.Core(), ""); err != nil {
state.HashMatch = false
state.HashError = err.Error()
} else {
state.HashMatch = true
}
stage, _, err := getEncryptionHashAnnotation(server.Runtime.Core.Core())
if err != nil {
return state, err
}
state.Stage = stage
active := true
for _, p := range providers {
if p.AESCBC != nil {
for _, aesKey := range p.AESCBC.Keys {
if active {
active = false
state.ActiveKey = aesKey.Name
} else {
state.InactiveKeys = append(state.InactiveKeys, aesKey.Name)
}
}
}
if p.Identity != nil {
active = false
}
}
return state, nil
}
func encryptionEnable(ctx context.Context, server *config.Control, enable bool) error {
providers, err := secretsencrypt.GetEncryptionProviders(server.Runtime)
if err != nil {
return err
}
if len(providers) > 2 {
return fmt.Errorf("more than 2 providers (%d) found in secrets encryption", len(providers))
}
curKeys, err := secretsencrypt.GetEncryptionKeys(server.Runtime)
if err != nil {
return err
}
if providers[1].Identity != nil && providers[0].AESCBC != nil && !enable {
logrus.Infoln("Disabling secrets encryption")
if err := secretsencrypt.WriteEncryptionConfig(server.Runtime, curKeys, enable); err != nil {
return err
}
} else if !enable {
logrus.Infoln("Secrets encryption already disabled")
return nil
} else if providers[0].Identity != nil && providers[1].AESCBC != nil && enable {
logrus.Infoln("Enabling secrets encryption")
if err := secretsencrypt.WriteEncryptionConfig(server.Runtime, curKeys, enable); err != nil {
return err
}
} else if enable {
logrus.Infoln("Secrets encryption already enabled")
return nil
} else {
return fmt.Errorf("unable to enable/disable secrets encryption, unknown configuration")
}
return cluster.Save(ctx, server, true)
}
func encryptionConfigHandler(ctx context.Context, server *config.Control) http.Handler {
return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
if req.TLS == nil {
resp.WriteHeader(http.StatusNotFound)
return
}
if req.Method != http.MethodPut {
resp.WriteHeader(http.StatusBadRequest)
return
}
encryptReq, err := getEncryptionRequest(req)
if err != nil {
resp.WriteHeader(http.StatusBadRequest)
resp.Write([]byte(err.Error()))
return
}
if encryptReq.Stage != nil {
switch *encryptReq.Stage {
case secretsencrypt.EncryptionPrepare:
err = encryptionPrepare(ctx, server, encryptReq.Force)
case secretsencrypt.EncryptionRotate:
err = encryptionRotate(ctx, server, encryptReq.Force)
case secretsencrypt.EncryptionReencryptActive:
err = encryptionReencrypt(ctx, server, encryptReq.Force, encryptReq.Skip)
default:
err = fmt.Errorf("unknown stage %s requested", *encryptReq.Stage)
}
} else if encryptReq.Enable != nil {
err = encryptionEnable(ctx, server, *encryptReq.Enable)
}
if err != nil {
genErrorMessage(resp, http.StatusBadRequest, err, "secrets-encrypt")
return
}
// If a user kills the k3s server immediately after this call, we run into issues where the files
// have not yet been written. This sleep ensures that things have time to sync to disk before
// the request completes.
time.Sleep(1 * time.Second)
resp.WriteHeader(http.StatusOK)
})
}
func encryptionPrepare(ctx context.Context, server *config.Control, force bool) error {
states := secretsencrypt.EncryptionStart + "-" + secretsencrypt.EncryptionReencryptFinished
if err := verifyEncryptionHashAnnotation(server.Runtime, server.Runtime.Core.Core(), states); err != nil && !force {
return err
}
curKeys, err := secretsencrypt.GetEncryptionKeys(server.Runtime)
if err != nil {
return err
}
if err := AppendNewEncryptionKey(&curKeys); err != nil {
return err
}
logrus.Infoln("Adding secrets-encryption key: ", curKeys[len(curKeys)-1])
if err := secretsencrypt.WriteEncryptionConfig(server.Runtime, curKeys, true); err != nil {
return err
}
nodeName := os.Getenv("NODE_NAME")
node, err := server.Runtime.Core.Core().V1().Node().Get(nodeName, metav1.GetOptions{})
if err != nil {
return err
}
if err = secretsencrypt.WriteEncryptionHashAnnotation(server.Runtime, node, secretsencrypt.EncryptionPrepare); err != nil {
return err
}
return cluster.Save(ctx, server, true)
}
func encryptionRotate(ctx context.Context, server *config.Control, force bool) error {
if err := verifyEncryptionHashAnnotation(server.Runtime, server.Runtime.Core.Core(), secretsencrypt.EncryptionPrepare); err != nil && !force {
return err
}
curKeys, err := secretsencrypt.GetEncryptionKeys(server.Runtime)
if err != nil {
return err
}
// Right rotate elements
rotatedKeys := append(curKeys[len(curKeys)-1:], curKeys[:len(curKeys)-1]...)
if err = secretsencrypt.WriteEncryptionConfig(server.Runtime, rotatedKeys, true); err != nil {
return err
}
logrus.Infoln("Encryption keys right rotated")
nodeName := os.Getenv("NODE_NAME")
node, err := server.Runtime.Core.Core().V1().Node().Get(nodeName, metav1.GetOptions{})
if err != nil {
return err
}
if err := secretsencrypt.WriteEncryptionHashAnnotation(server.Runtime, node, secretsencrypt.EncryptionRotate); err != nil {
return err
}
return cluster.Save(ctx, server, true)
}
func encryptionReencrypt(ctx context.Context, server *config.Control, force bool, skip bool) error {
if err := verifyEncryptionHashAnnotation(server.Runtime, server.Runtime.Core.Core(), secretsencrypt.EncryptionRotate); err != nil && !force {
return err
}
server.EncryptForce = force
server.EncryptSkip = skip
nodeName := os.Getenv("NODE_NAME")
node, err := server.Runtime.Core.Core().V1().Node().Get(nodeName, metav1.GetOptions{})
if err != nil {
return err
}
reencryptHash, err := secretsencrypt.GenReencryptHash(server.Runtime, secretsencrypt.EncryptionReencryptRequest)
if err != nil {
return err
}
ann := secretsencrypt.EncryptionReencryptRequest + "-" + reencryptHash
node.Annotations[secretsencrypt.EncryptionHashAnnotation] = ann
if _, err = server.Runtime.Core.Core().V1().Node().Update(node); err != nil {
return err
}
logrus.Debugf("encryption hash annotation set successfully on node: %s\n", node.ObjectMeta.Name)
return nil
}
func AppendNewEncryptionKey(keys *[]apiserverconfigv1.Key) error {
aescbcKey := make([]byte, aescbcKeySize)
_, err := rand.Read(aescbcKey)
if err != nil {
return err
}
encodedKey := base64.StdEncoding.EncodeToString(aescbcKey)
newKey := []apiserverconfigv1.Key{
{
Name: "aescbckey-" + time.Now().Format(time.RFC3339),
Secret: encodedKey,
},
}
*keys = append(*keys, newKey...)
return nil
}
func getEncryptionHashAnnotation(core core.Interface) (string, string, error) {
nodeName := os.Getenv("NODE_NAME")
node, err := core.V1().Node().Get(nodeName, metav1.GetOptions{})
if err != nil {
return "", "", err
}
if _, ok := node.Labels[ControlPlaneRoleLabelKey]; !ok {
return "", "", fmt.Errorf("cannot manage secrets encryption on non control-plane node %s", nodeName)
}
if ann, ok := node.Annotations[secretsencrypt.EncryptionHashAnnotation]; ok {
split := strings.Split(ann, "-")
if len(split) != 2 {
return "", "", fmt.Errorf("invalid annotation %s found on node %s", ann, nodeName)
}
return split[0], split[1], nil
}
return "", "", fmt.Errorf("missing annotation on node %s", nodeName)
}
// verifyEncryptionHashAnnotation checks that all nodes are on the same stage,
// and that a request for new stage is valid
func verifyEncryptionHashAnnotation(runtime *config.ControlRuntime, core core.Interface, prevStage string) error {
var firstHash string
var firstNodeName string
first := true
labelSelector := labels.Set{ControlPlaneRoleLabelKey: "true"}.String()
nodes, err := core.V1().Node().List(metav1.ListOptions{LabelSelector: labelSelector})
if err != nil {
return err
}
for _, node := range nodes.Items {
hash, ok := node.Annotations[secretsencrypt.EncryptionHashAnnotation]
if ok && first {
firstHash = hash
first = false
firstNodeName = node.ObjectMeta.Name
} else if ok && hash != firstHash {
return fmt.Errorf("hash does not match between %s and %s", firstNodeName, node.ObjectMeta.Name)
}
}
if prevStage == "" {
return nil
}
oldStage, oldHash, err := getEncryptionHashAnnotation(core)
if err != nil {
return err
}
encryptionConfigHash, err := secretsencrypt.GenEncryptionConfigHash(runtime)
if err != nil {
return err
}
if !strings.Contains(prevStage, oldStage) {
return fmt.Errorf("incorrect stage: %s found on node %s", oldStage, nodes.Items[0].ObjectMeta.Name)
} else if oldHash != encryptionConfigHash {
return fmt.Errorf("invalid hash: %s found on node %s", oldHash, nodes.Items[0].ObjectMeta.Name)
}
return nil
}
// genErrorMessage sends and logs a random error ID so that logs can be correlated
// between the REST API (which does not provide any detailed error output, to avoid
// information disclosure) and the server logs.
func genErrorMessage(resp http.ResponseWriter, statusCode int, passedErr error, component string) {
errID, err := rand.Int(rand.Reader, big.NewInt(99999))
if err != nil {
resp.WriteHeader(http.StatusInternalServerError)
resp.Write([]byte(err.Error()))
return
}
logrus.Warnf("%s error ID %05d: %s", component, errID, passedErr.Error())
resp.WriteHeader(statusCode)
resp.Write([]byte(fmt.Sprintf("%s error ID %05d", component, errID)))
}