k3s/pkg/server/router.go

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package server
import (
"context"
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"crypto"
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"crypto/x509"
"fmt"
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"net"
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"net/http"
"os"
"path"
"path/filepath"
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"strconv"
"strings"
"sync"
"time"
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"github.com/gorilla/mux"
"github.com/k3s-io/k3s/pkg/bootstrap"
"github.com/k3s-io/k3s/pkg/cli/cmds"
"github.com/k3s-io/k3s/pkg/daemons/config"
"github.com/k3s-io/k3s/pkg/generated/clientset/versioned/scheme"
"github.com/k3s-io/k3s/pkg/nodepassword"
"github.com/k3s-io/k3s/pkg/util"
"github.com/k3s-io/k3s/pkg/version"
"github.com/pkg/errors"
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certutil "github.com/rancher/dynamiclistener/cert"
coreclient "github.com/rancher/wrangler/pkg/generated/controllers/core/v1"
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"github.com/sirupsen/logrus"
corev1 "k8s.io/api/core/v1"
apierrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime/schema"
"k8s.io/apimachinery/pkg/types"
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"k8s.io/apimachinery/pkg/util/json"
"k8s.io/apimachinery/pkg/util/wait"
"k8s.io/apiserver/pkg/authentication/user"
"k8s.io/apiserver/pkg/endpoints/handlers/responsewriters"
"k8s.io/apiserver/pkg/endpoints/request"
bootstrapapi "k8s.io/cluster-bootstrap/token/api"
"k8s.io/kubernetes/pkg/auth/nodeidentifier"
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)
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const (
staticURL = "/static/"
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)
var (
identifier = nodeidentifier.NewDefaultNodeIdentifier()
)
func router(ctx context.Context, config *Config, cfg *cmds.Server) http.Handler {
serverConfig := &config.ControlConfig
nodeAuth := passwordBootstrap(ctx, config)
prefix := "/v1-" + version.Program
authed := mux.NewRouter().SkipClean(true)
authed.Use(authMiddleware(serverConfig, version.Program+":agent", user.NodesGroup, bootstrapapi.BootstrapDefaultGroup))
authed.Path(prefix + "/serving-kubelet.crt").Handler(servingKubeletCert(serverConfig, serverConfig.Runtime.ServingKubeletKey, nodeAuth))
authed.Path(prefix + "/client-kubelet.crt").Handler(clientKubeletCert(serverConfig, serverConfig.Runtime.ClientKubeletKey, nodeAuth))
authed.Path(prefix + "/client-kube-proxy.crt").Handler(fileHandler(serverConfig.Runtime.ClientKubeProxyCert, serverConfig.Runtime.ClientKubeProxyKey))
authed.Path(prefix + "/client-" + version.Program + "-controller.crt").Handler(fileHandler(serverConfig.Runtime.ClientK3sControllerCert, serverConfig.Runtime.ClientK3sControllerKey))
authed.Path(prefix + "/client-ca.crt").Handler(fileHandler(serverConfig.Runtime.ClientCA))
authed.Path(prefix + "/server-ca.crt").Handler(fileHandler(serverConfig.Runtime.ServerCA))
authed.Path(prefix + "/apiservers").Handler(apiserversHandler(serverConfig))
authed.Path(prefix + "/config").Handler(configHandler(serverConfig, cfg))
authed.Path(prefix + "/readyz").Handler(readyzHandler(serverConfig))
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if cfg.DisableAPIServer {
authed.NotFoundHandler = apiserverDisabled()
} else {
authed.NotFoundHandler = apiserver(serverConfig.Runtime)
}
nodeAuthed := mux.NewRouter().SkipClean(true)
nodeAuthed.NotFoundHandler = authed
nodeAuthed.Use(authMiddleware(serverConfig, user.NodesGroup))
nodeAuthed.Path(prefix + "/connect").Handler(serverConfig.Runtime.Tunnel)
serverAuthed := mux.NewRouter().SkipClean(true)
serverAuthed.NotFoundHandler = nodeAuthed
serverAuthed.Use(authMiddleware(serverConfig, version.Program+":server"))
serverAuthed.Path(prefix + "/encrypt/status").Handler(encryptionStatusHandler(serverConfig))
serverAuthed.Path(prefix + "/encrypt/config").Handler(encryptionConfigHandler(ctx, serverConfig))
serverAuthed.Path(prefix + "/cert/cacerts").Handler(caCertReplaceHandler(serverConfig))
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serverAuthed.Path("/db/info").Handler(nodeAuthed)
serverAuthed.Path(prefix + "/server-bootstrap").Handler(bootstrapHandler(serverConfig.Runtime))
systemAuthed := mux.NewRouter().SkipClean(true)
systemAuthed.NotFoundHandler = serverAuthed
systemAuthed.MethodNotAllowedHandler = serverAuthed
systemAuthed.Use(authMiddleware(serverConfig, user.SystemPrivilegedGroup))
systemAuthed.Methods(http.MethodConnect).Handler(serverConfig.Runtime.Tunnel)
staticDir := filepath.Join(serverConfig.DataDir, "static")
router := mux.NewRouter().SkipClean(true)
router.NotFoundHandler = systemAuthed
router.PathPrefix(staticURL).Handler(serveStatic(staticURL, staticDir))
router.Path("/cacerts").Handler(cacerts(serverConfig.Runtime.ServerCA))
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router.Path("/ping").Handler(ping())
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return router
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}
func apiserver(runtime *config.ControlRuntime) http.Handler {
return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
if runtime != nil && runtime.APIServer != nil {
runtime.APIServer.ServeHTTP(resp, req)
} else {
responsewriters.ErrorNegotiated(
apierrors.NewServiceUnavailable("apiserver not ready"),
scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
)
}
})
}
func apiserverDisabled() http.Handler {
return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
responsewriters.ErrorNegotiated(
apierrors.NewServiceUnavailable("apiserver disabled"),
scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
)
})
}
func bootstrapHandler(runtime *config.ControlRuntime) http.Handler {
if runtime.HTTPBootstrap {
return bootstrap.Handler(&runtime.ControlRuntimeBootstrap)
}
return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
logrus.Warnf("Received HTTP bootstrap request from %s, but embedded etcd is not enabled.", req.RemoteAddr)
responsewriters.ErrorNegotiated(
apierrors.NewBadRequest("etcd disabled"),
scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
)
})
}
func cacerts(serverCA string) http.Handler {
var ca []byte
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return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
if ca == nil {
var err error
ca, err = os.ReadFile(serverCA)
if err != nil {
sendError(err, resp, req)
return
}
}
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resp.Header().Set("content-type", "text/plain")
resp.Write(ca)
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})
}
func getNodeInfo(req *http.Request) (*nodeInfo, error) {
user, ok := request.UserFrom(req.Context())
if !ok {
return nil, errors.New("auth user not set")
}
nodeName := req.Header.Get(version.Program + "-Node-Name")
if nodeName == "" {
return nil, errors.New("node name not set")
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}
nodePassword := req.Header.Get(version.Program + "-Node-Password")
if nodePassword == "" {
return nil, errors.New("node password not set")
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}
return &nodeInfo{
Name: strings.ToLower(nodeName),
Password: nodePassword,
User: user,
}, nil
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}
func getCACertAndKeys(caCertFile, caKeyFile, signingKeyFile string) ([]*x509.Certificate, crypto.Signer, crypto.Signer, error) {
keyBytes, err := os.ReadFile(signingKeyFile)
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if err != nil {
return nil, nil, nil, err
}
key, err := certutil.ParsePrivateKeyPEM(keyBytes)
if err != nil {
return nil, nil, nil, err
}
caKeyBytes, err := os.ReadFile(caKeyFile)
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if err != nil {
return nil, nil, nil, err
}
caKey, err := certutil.ParsePrivateKeyPEM(caKeyBytes)
if err != nil {
return nil, nil, nil, err
}
caBytes, err := os.ReadFile(caCertFile)
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if err != nil {
return nil, nil, nil, err
}
caCert, err := certutil.ParseCertsPEM(caBytes)
if err != nil {
return nil, nil, nil, err
}
return caCert, caKey.(crypto.Signer), key.(crypto.Signer), nil
}
func servingKubeletCert(server *config.Control, keyFile string, auth nodePassBootstrapper) http.Handler {
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return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
if req.TLS == nil {
resp.WriteHeader(http.StatusNotFound)
return
}
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nodeName, errCode, err := auth(req)
if err != nil {
sendError(err, resp, req, errCode)
return
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}
caCerts, caKey, key, err := getCACertAndKeys(server.Runtime.ServerCA, server.Runtime.ServerCAKey, server.Runtime.ServingKubeletKey)
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if err != nil {
sendError(err, resp, req)
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return
}
ips := []net.IP{net.ParseIP("127.0.0.1")}
if nodeIP := req.Header.Get(version.Program + "-Node-IP"); nodeIP != "" {
for _, v := range strings.Split(nodeIP, ",") {
ip := net.ParseIP(v)
if ip == nil {
sendError(fmt.Errorf("invalid node IP address %s", ip), resp, req)
return
}
ips = append(ips, ip)
}
}
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cert, err := certutil.NewSignedCert(certutil.Config{
CommonName: nodeName,
Usages: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
AltNames: certutil.AltNames{
DNSNames: []string{nodeName, "localhost"},
IPs: ips,
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},
}, key, caCerts[0], caKey)
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if err != nil {
sendError(err, resp, req)
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return
}
keyBytes, err := os.ReadFile(keyFile)
if err != nil {
http.Error(resp, err.Error(), http.StatusInternalServerError)
return
}
resp.Write(util.EncodeCertsPEM(cert, caCerts))
resp.Write(keyBytes)
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})
}
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func clientKubeletCert(server *config.Control, keyFile string, auth nodePassBootstrapper) http.Handler {
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return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
if req.TLS == nil {
resp.WriteHeader(http.StatusNotFound)
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return
}
nodeName, errCode, err := auth(req)
if err != nil {
sendError(err, resp, req, errCode)
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return
}
caCerts, caKey, key, err := getCACertAndKeys(server.Runtime.ClientCA, server.Runtime.ClientCAKey, server.Runtime.ClientKubeletKey)
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if err != nil {
sendError(err, resp, req)
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return
}
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cert, err := certutil.NewSignedCert(certutil.Config{
CommonName: "system:node:" + nodeName,
Organization: []string{user.NodesGroup},
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Usages: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
}, key, caCerts[0], caKey)
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if err != nil {
sendError(err, resp, req)
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return
}
keyBytes, err := os.ReadFile(keyFile)
if err != nil {
http.Error(resp, err.Error(), http.StatusInternalServerError)
return
}
resp.Write(util.EncodeCertsPEM(cert, caCerts))
resp.Write(keyBytes)
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})
}
func fileHandler(fileName ...string) http.Handler {
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return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
if req.TLS == nil {
resp.WriteHeader(http.StatusNotFound)
return
}
resp.Header().Set("Content-Type", "text/plain")
if len(fileName) == 1 {
http.ServeFile(resp, req, fileName[0])
return
}
for _, f := range fileName {
bytes, err := os.ReadFile(f)
if err != nil {
logrus.Errorf("Failed to read %s: %v", f, err)
resp.WriteHeader(http.StatusInternalServerError)
return
}
resp.Write(bytes)
}
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})
}
func apiserversHandler(server *config.Control) http.Handler {
var endpointsClient coreclient.EndpointsClient
return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
var endpoints []string
if endpointsClient == nil {
if server.Runtime.Core != nil {
endpointsClient = server.Runtime.Core.Core().V1().Endpoints()
}
}
if endpointsClient != nil {
if endpoint, _ := endpointsClient.Get("default", "kubernetes", metav1.GetOptions{}); endpoint != nil {
endpoints = util.GetAddresses(endpoint)
}
}
resp.Header().Set("content-type", "application/json")
if err := json.NewEncoder(resp).Encode(endpoints); err != nil {
logrus.Errorf("Failed to encode apiserver endpoints: %v", err)
resp.WriteHeader(http.StatusInternalServerError)
}
})
}
func configHandler(server *config.Control, cfg *cmds.Server) http.Handler {
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return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
if req.TLS == nil {
resp.WriteHeader(http.StatusNotFound)
return
}
// Startup hooks may read and modify cmds.Server in a goroutine, but as these are copied into
// config.Control before the startup hooks are called, any modifications need to be sync'd back
// into the struct before it is sent to agents.
// At this time we don't sync all the fields, just those known to be touched by startup hooks.
server.DisableKubeProxy = cfg.DisableKubeProxy
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resp.Header().Set("content-type", "application/json")
if err := json.NewEncoder(resp).Encode(server); err != nil {
logrus.Errorf("Failed to encode agent config: %v", err)
resp.WriteHeader(http.StatusInternalServerError)
}
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})
}
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func readyzHandler(server *config.Control) http.Handler {
return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
code := http.StatusOK
data := []byte("ok")
if server.Runtime.Core == nil {
code = http.StatusInternalServerError
data = []byte("runtime core not ready")
}
resp.WriteHeader(code)
resp.Header().Set("Content-Type", "text/plain")
resp.Header().Set("Content-length", strconv.Itoa(len(data)))
resp.Write(data)
})
}
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func ping() http.Handler {
return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
data := []byte("pong")
resp.Header().Set("Content-Type", "text/plain")
resp.Header().Set("Content-Length", strconv.Itoa(len(data)))
resp.Write(data)
})
}
func serveStatic(urlPrefix, staticDir string) http.Handler {
return http.StripPrefix(urlPrefix, http.FileServer(http.Dir(staticDir)))
}
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func sendError(err error, resp http.ResponseWriter, req *http.Request, status ...int) {
var code int
if len(status) == 1 {
code = status[0]
}
if code == 0 || code == http.StatusOK {
code = http.StatusInternalServerError
}
logrus.Errorf("Sending HTTP %d response to %s: %v", code, req.RemoteAddr, err)
responsewriters.ErrorNegotiated(
apierrors.NewGenericServerResponse(code, req.Method, schema.GroupResource{}, req.URL.Path, err.Error(), 0, true),
scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
)
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}
// nodePassBootstrapper returns a node name, or http error code and error
type nodePassBootstrapper func(req *http.Request) (string, int, error)
// nodeInfo contains information on the requesting node, derived from auth creds
// and request headers.
type nodeInfo struct {
Name string
Password string
User user.Info
}
func passwordBootstrap(ctx context.Context, config *Config) nodePassBootstrapper {
runtime := config.ControlConfig.Runtime
deferredNodes := map[string]bool{}
var secretClient coreclient.SecretClient
var nodeClient coreclient.NodeClient
var mu sync.Mutex
return nodePassBootstrapper(func(req *http.Request) (string, int, error) {
node, err := getNodeInfo(req)
if err != nil {
return "", http.StatusBadRequest, err
}
nodeName, isNodeAuth := identifier.NodeIdentity(node.User)
if isNodeAuth && nodeName != node.Name {
return "", http.StatusBadRequest, errors.New("header node name does not match auth node name")
}
if secretClient == nil || nodeClient == nil {
if runtime.Core != nil {
// initialize the client if we can
secretClient = runtime.Core.Core().V1().Secret()
nodeClient = runtime.Core.Core().V1().Node()
} else if node.Name == os.Getenv("NODE_NAME") {
// If we're verifying our own password, verify it locally and ensure a secret later.
return verifyLocalPassword(ctx, config, &mu, deferredNodes, node)
} else if config.ControlConfig.DisableAPIServer && !isNodeAuth {
// If we're running on an etcd-only node, and the request didn't use Node Identity auth,
// defer node password verification until an apiserver joins the cluster.
return verifyRemotePassword(ctx, config, &mu, deferredNodes, node)
} else {
// Otherwise, reject the request until the core is ready.
return "", http.StatusServiceUnavailable, errors.New("runtime core not ready")
}
}
// verify that the node exists, if using Node Identity auth
if err := verifyNode(ctx, nodeClient, node); err != nil {
return "", http.StatusUnauthorized, err
}
// verify that the node password secret matches, or create it if it does not
if err := nodepassword.Ensure(secretClient, node.Name, node.Password); err != nil {
// if the verification failed, reject the request
if errors.Is(err, nodepassword.ErrVerifyFailed) {
return "", http.StatusForbidden, err
}
// If verification failed due to an error creating the node password secret, allow
// the request, but retry verification until the outage is resolved. This behavior
// allows nodes to join the cluster during outages caused by validating webhooks
// blocking secret creation - if the outage requires new nodes to join in order to
// run the webhook pods, we must fail open here to resolve the outage.
return verifyRemotePassword(ctx, config, &mu, deferredNodes, node)
}
return node.Name, http.StatusOK, nil
})
}
func verifyLocalPassword(ctx context.Context, config *Config, mu *sync.Mutex, deferredNodes map[string]bool, node *nodeInfo) (string, int, error) {
// use same password file location that the agent creates
nodePasswordRoot := "/"
if config.ControlConfig.Rootless {
nodePasswordRoot = filepath.Join(path.Dir(config.ControlConfig.DataDir), "agent")
}
nodeConfigPath := filepath.Join(nodePasswordRoot, "etc", "rancher", "node")
nodePasswordFile := filepath.Join(nodeConfigPath, "password")
passBytes, err := os.ReadFile(nodePasswordFile)
if err != nil {
return "", http.StatusInternalServerError, errors.Wrap(err, "unable to read node password file")
}
passHash, err := nodepassword.Hasher.CreateHash(strings.TrimSpace(string(passBytes)))
if err != nil {
return "", http.StatusInternalServerError, errors.Wrap(err, "unable to hash node password file")
}
if err := nodepassword.Hasher.VerifyHash(passHash, node.Password); err != nil {
return "", http.StatusForbidden, errors.Wrap(err, "unable to verify local node password")
}
mu.Lock()
defer mu.Unlock()
if _, ok := deferredNodes[node.Name]; !ok {
deferredNodes[node.Name] = true
go ensureSecret(ctx, config, node)
logrus.Infof("Password verified locally for node %s", node.Name)
}
return node.Name, http.StatusOK, nil
}
func verifyRemotePassword(ctx context.Context, config *Config, mu *sync.Mutex, deferredNodes map[string]bool, node *nodeInfo) (string, int, error) {
mu.Lock()
defer mu.Unlock()
if _, ok := deferredNodes[node.Name]; !ok {
deferredNodes[node.Name] = true
go ensureSecret(ctx, config, node)
logrus.Infof("Password verification deferred for node %s", node.Name)
}
return node.Name, http.StatusOK, nil
}
func verifyNode(ctx context.Context, nodeClient coreclient.NodeClient, node *nodeInfo) error {
if nodeName, isNodeAuth := identifier.NodeIdentity(node.User); isNodeAuth {
if _, err := nodeClient.Get(nodeName, metav1.GetOptions{}); err != nil {
return errors.Wrap(err, "unable to verify node identity")
}
}
return nil
}
func ensureSecret(ctx context.Context, config *Config, node *nodeInfo) {
runtime := config.ControlConfig.Runtime
wait.PollImmediateUntilWithContext(ctx, time.Second*5, func(ctx context.Context) (bool, error) {
if runtime.Core != nil {
secretClient := runtime.Core.Core().V1().Secret()
// This is consistent with events attached to the node generated by the kubelet
// https://github.com/kubernetes/kubernetes/blob/612130dd2f4188db839ea5c2dea07a96b0ad8d1c/pkg/kubelet/kubelet.go#L479-L485
nodeRef := &corev1.ObjectReference{
Kind: "Node",
Name: node.Name,
UID: types.UID(node.Name),
Namespace: "",
}
if err := nodepassword.Ensure(secretClient, node.Name, node.Password); err != nil {
runtime.Event.Eventf(nodeRef, corev1.EventTypeWarning, "NodePasswordValidationFailed", "Deferred node password secret validation failed: %v", err)
// Return true to stop polling if the password verification failed; only retry on secret creation errors.
return errors.Is(err, nodepassword.ErrVerifyFailed), nil
}
runtime.Event.Event(nodeRef, corev1.EventTypeNormal, "NodePasswordValidationComplete", "Deferred node password secret validation complete")
return true, nil
}
return false, nil
})
}